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  • Other Sources  (2,105)
  • 2020-2023  (2,105)
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  • 1
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    The forcings of the Mediterranean Sea and the physical properties of its water masses (2023)
    Elsevier
    Details
    Publication Date: 2022-12-22
    Description: This chapter aims at introducing the reader to general concepts about the main forcings of the Mediterranean Sea, in terms of exchanges through the Strait of Gibraltar, and air-sea exchanges of heat, freshwater, and momentum. These forcings are also responsible for the peculiar characteristics of Mediterranean water masses. Therefore, the chapter continues with giving a general explanation on water mass analysis, and then it describes the properties and vertical and horizontal distributions of the main Mediterranean water masses. To conclude, the reader is introduced to the use of other (biogeochemical, and chemical) tracers of water masses, with a focus on the Mediterranean Sea.
    Type: Book chapter , PeerReviewed
    Format: text
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  • 2
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    Seasonal Differences in the Attenuation of Polar Trace Organics in the Hyporheic Zone of an Urban Stream (2022)
    Details
    Publication Date: 2022-04-04
    Description: Attenuation of trace organic compounds (TrOCs) in a river occurs to a large extent in its hyporheic zone. A major part of the attenuation of polar TrOCs is of microbial origin. As microbial activity depends on temperature and redox conditions, seasonal differences in TrOC attenuation are likely. We investigated TrOC attenuation at a river influenced by treated wastewater during two sampling campaigns, one in summer and one in winter. In addition to redox conditions and temperature, we also determined residence times of porewater in sediment using three methods: (a) non‐parametric deconvolution of electrical conductivity time series, (b) the model VFLUX 2.0 based on temperature time series (only summer), and (c) applying Darcy's law to differences in hydraulic heads (only summer). Contrary to our expectations, we found higher attenuation for 12 out of 18 TrOCs in winter, while three TrOCs were better attenuated in summer. Sediment conditions varied between seasons as more of the top sandy layer with a higher hydraulic permeability accumulated on the river bed in summer. As a result, residence times in the sediment were shorter in summer. In winter, longer residence times, lower temperatures, and a steeper oxygen gradient in sediment coincided with higher TrOC attenuation. Further research is needed to understand our unexpected findings and underlying mechanisms.
    Description: Key Points: The attenuation of 12 out of 18 trace organic compounds (TrOCs) in the hyporheic zone was higher in winter while three TrOCs were attenuated better in summer. Residence times in sediment were longer and more diverse in winter. The extent of the oxic sediment was similar between seasons but the gradient from the oxic to anoxic zone was steeper in winter.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: EC | H2020 | H2020 Priority Excellent Science | H2020 Marie Skłodowska‐Curie Actions (MSCA) http://dx.doi.org/10.13039/100010665
    Description: University of Western Australia ‐ University Postgraduate Award
    Description: Australian Government Research Training Program Scholarship
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.18728/igb-fred-578.0
    Keywords: ddc:628.162
    Language: English
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  • 3
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    Iron Exports From Catchments Are Constrained by Redox Status and Topography (2022)
    Details
    Publication Date: 2022-04-04
    Description: Fe(III) hydroxides stabilize organic carbon (OC) and P in soils. Observations of rising stream Fe concentrations are controversially posited to result from a flushing of iron‐rich deeper soil layers or a decrease of competing electron acceptors inhibiting Fe reduction (NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ and SO42− $\mathrm{S}{{\mathrm{O}}_{4}}^{2-}$). Here, we argue that catchment topography constrains the release of Fe, OC, and P to streams. We therefore incubated organic topsoil and mineral subsoil and modified the availability of NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$. We found that Fe leaching was highest in topsoil. Fe, OC, and P released at quantities proportional to their ratios in the source soil. Supply of NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ reduced Fe leaching to 18% and increased pore water OC:Fe and P:Fe ratios. Subsoil, however, was an insignificant Fe source (〈0.5%). Here, the leached quantities of Fe, OC and P were highly disproportionate to the soil source with an excess of released OC and P. We tested if experimental findings scale up using data from 88 German catchments representing gradients in NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ concentration and topography. Average stream Fe concentrations increased with decreasing NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ and were high in catchments with shallow topography where high groundwater levels support reductive processes and topsoils are hydrologically connected to streams; but Fe concentrations were low in catchments with steep topography where flow occurs primarily through subsoils. OC:Fe and P:Fe ratios in the streams similarly varied by NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ and topography. This corroborates the findings from the laboratory experiment and suggests that catchment topography and competing electron acceptors constrain the formation of Fe‐reducing conditions and control the release of Fe, OC, and P to streams.
    Description: Plain Language Summary: Iron is the second most abundant metal in the crust; its cycle is tightly connected to those of carbon, oxygen, and sulfur. The oxidized form (FeIII) is almost insoluble, but Fe can be mobilized by complexation or microbial Fe reduction. Both processes depend on availability of organic C. We found that Fe concentrations in streams were constrained by the topography of catchments and NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ abundance. Shallower catchments are characterized by higher groundwater tables connecting the organic topsoils efficiently to streams. NO3− $\mathrm{N}{{\mathrm{O}}_{3}}^{-}$ suppresses Fe reduction as a competing electron acceptor to Fe. We conclude that trends in soil wetness or atmospheric N deposition can change the stability of Fe and thus the release of PO43− $\mathrm{P}{{\mathrm{O}}_{4}}^{3-}$ and harmful metals to surface waters.
    Description: Key Points: Organic topsoils leach substantial amounts of Fe when incubated in the absence of NO3, a competing electron acceptor that inhibits Fe reduction. Shallow catchments with fluvially coupled topsoils and low NO3 availability release 200 fold more Fe than steep ones with high NO3 abundance. Catchment topography and NO3 availability explain 62%–64% of the variability of Fe concentration and OC:Fe and P:Fe ratios across 88 streams.
    Description: EFRE‐Europe
    Description: https://doi.org/10.4211/hs.43601618877945c5a46b715aa98db729
    Keywords: ddc:551.9
    Language: English
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  • 4
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    Feasibility of pXRF to evaluate chosen heavy metals in soil highly influenced by municipal waste disposal—A monitoring study of a former sewage farm (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2022-04-04
    Description: Sewage disposal onto agricultural land may result in the high accumulation of organic wastes, which questions the applicability of typical elemental analysis used for the soil components. To monitor the contamination status of agricultural soils at a former sedimentation basin, after the long‐term cessation of wastewater irrigation, 110 locations (15–20 cm depth) and 4 boreholes (up to 100 cm depth) were sampled to determine pH, loss on ignition, and concentration of Ni, Cu, Pb, Zn, and Cr. Additionally, the applicability of portable X‐ray fluorescence (pXRF) for the soil samples highly influenced by the organic wastes was evaluated. The study revealed the presence of a relatively homogenous sewage waste layer (depth of 20 cm), characterized by slightly acidic to neutral pH (6.3–7.5), high organic matter (OM) accumulation (up to 49%), and elevated concentration (mg kg −1) ranges between: Pb (5–321), Cu (31–2828), Ni (10–193), Cr (14–966), and Zn (76–6639). The pXRF analysis revealed metal concentration increase in mineral samples (up to 50%). The regression models and correction factors demonstrated high correlation and significance of pXRF measurement with response to increasing OM content, with the lowest r 2 = 0.86 obtained for Ni. Correlation of pXRF and AES measurement illustrated element‐dependent response for soils high in organics. Zn, Cu, and Cr pXRF analysis led to a slight underestimation in lower values, but overall good correlations (0.87; 0.89; and 0.88 respectively). Pb and Ni pXRF measurement revealed higher deviation from the reference in both lower and higher concentrations (0.74 and 0.70, respectively).
    Description: German Federation of Industrial Research Associations http://dx.doi.org/10.13039/501100002723
    Description: Federal Ministry for Economic Affairs and Energy http://dx.doi.org/10.13039/501100006360
    Keywords: ddc:577.14
    Language: English
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  • 5
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    The Goldilocks Zone in Cooling Demand: What Can We Do Better? (2022)
    Details
    Publication Date: 2022-04-07
    Description: The higher frequency and intensity of sustained heat events have increased the demand for cooling energy across the globe. Current estimates of summer‐time energy demand are primarily based on Cooling Degree Days (CDD), representing the number of degrees a day's average temperature exceeds a predetermined comfort zone temperature. Through a comprehensive analysis of the historical energy demand data across the USA, we show that the commonly used CDD estimates fall significantly short (±25%) of capturing regional thermal comfort levels. Moreover, given the increasingly compelling evidence that air temperature alone is not sufficient for characterizing human thermal comfort, we extend the widely used CDD calculation to heat index, which accounts for both air temperature and humidity. Our results indicate significant mis‐estimation of regional thermal comfort when humidity is ignored. Our findings have significant implications for the security, sustainability, and resilience of the grid under climate change.
    Description: Plain Language Summary: Hotter summer days and more frequent and intense heatwaves are causing a sharp rise in demand for air conditioning across the globe. Accurate estimation of demand for space cooling is an integral component of resilient planning, operation, and management of the grid. One widely used metric for characterizing this demand is the Cooling Degree Days (CDD), which is calculated by measuring the difference between the mean daily temperature and a pre‐defined base temperature that represents a “comfort zone.” In this study, we analyze historical data on climate and energy demand and find that the most frequently used base temperature of 65°F in CDD calculations leads to mis‐characterizing comfort zones across different geographic areas in the United States. This can cause significant under‐ or over‐estimations of cooling energy demand. Moreover, we extend the temperature‐based CDD calculations to also account for the role of humidity and demonstrate the cost of ignoring humidity in CDD calculations under present and future climate conditions.
    Description: Key Points: Analysis of electricity demand shows that the widely used Cooling Degree Days (CDD) estimates fall short of capturing regional thermal comfort zones. Estimates of air conditioning penetration and affordability based on traditional calculation of CDD can lead to significant misestimation. Extending CDD calculations to include humidity improves the characterization of climate‐demand nexus under present and future climate.
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Keywords: ddc:333.79
    Language: English
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  • 6
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    Vertically Divergent Responses of SOC Decomposition to Soil Moisture in a Changing Climate (2022)
    Details
    Publication Date: 2022-04-07
    Description: The role of soil moisture for organic matter decomposition rates remains poorly understood and underrepresented in Earth System Models (ESMs). We apply the Dual Arrhenius Michaelis‐Menten (DAMM) model to a selection of ESM soil temperature and moisture outputs to investigate their effects on decomposition rates, at different soil depths, for a historical period and a future climate period. Our key finding is that the inclusion of soil moisture controls has diverging effects on both the speed and direction of projected decomposition rates (up to ±20%), compared to a temperature‐only approach. In the top soil, the majority of these changes is driven by substrate availability. In deeper soil layers, oxygen availability plays a relatively stronger role. Owing to these different moisture controls along the soil depth, our study highlights the need for depth‐resolved inclusion of soil moisture effects on decomposition rates within ESMs. This is particularly important for C‐rich soils in regions which may be subject to strong future warming and vertically opposing moisture changes, such as the peat soils at northern high latitudes.
    Description: Plain Language Summary: Soils contain a lot of carbon (C). Earth System Models (ESMs) predict that the amount of C released from soils into the atmosphere as CO2 will increase in response to increased warming and microbial activity. Soil moisture also controls microbial C decomposition, but most ESMs do not yet describe this process very well. In this study we apply a simple equation to different ESMs, to see how both temperature and soil moisture change microbial decomposition under future climate. First, we show that the speed of C released into the atmosphere changes when we include soil moisture changes, compared to what is expected due to warming alone. Second, we found that the future speed at which carbon that can be decomposed in the topsoil mainly depends on how much carbon microbes have access to, but that in the deeper soil this process becomes much more affected by the absence/presence of oxygen. Including these soil moisture interactions in ESMs for different soil depths is important to predict whether soils will store more or less C in the future. Our findings are particularly relevant for high latitude soils which store large amounts of C, will warm fast, and experience frequent (re)wetting and drying.
    Description: Key Points: Considering soil moisture effects can change modeled decomposition rates by up to ±20% compared to considering only temperature effects. The majority of these changes are driven by substrate availability, in particular in the top soil. In the subsoil, oxygen availability becomes an increasingly important factor.
    Description: Norwegian Research Council
    Description: https://doi.org/10.5281/zenodo.5654554
    Keywords: ddc:631.4
    Language: English
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  • 7
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    Uncertainty in Aerosol Optical Depth From Modern Aerosol‐Climate Models, Reanalyses, and Satellite Products (2022)
    Details
    Publication Date: 2022-04-01
    Description: Despite the implication of aerosols for the radiation budget, there are persistent differences in data for the aerosol optical depth (τ) for 1998–2019. This study presents a comprehensive evaluation of the large‐scale spatio‐temporal patterns of mid‐visible τ from modern data sets. In total, we assessed 94 different global data sets from eight satellite retrievals, four aerosol‐climate model ensembles, one operational ensemble product, two reanalyses, one climatology and one merged satellite product. We include the new satellite data SLSTR and aerosol‐climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and the Aerosol Comparisons between Observations and Models Phase 3 (AeroCom‐III). Our intercomparison highlights model differences and observational uncertainty. Spatial mean τ for 60°N – 60°S ranges from 0.124 to 0.164 for individual satellites, with a mean of 0.14. Averaged τ from aerosol‐climate model ensembles fall within this satellite range, but individual models do not. Our assessment suggests no systematic improvement compared to CMIP5 and AeroCom‐I. Although some regional biases have been reduced, τ from both CMIP6 and AeroCom‐III are for instance substantially larger along extra‐tropical storm tracks compared to the satellite products. The considerable uncertainty in observed τ implies that a model evaluation based on a single satellite product might draw biased conclusions. This underlines the need for continued efforts to improve both model and satellite estimates of τ, for example, through measurement campaigns in areas of particularly uncertain satellite estimates identified in this study, to facilitate a better understanding of aerosol effects in the Earth system.
    Description: Plain Language Summary: Aerosols are known to affect atmospheric processes. For instance, particles emitted during dust storms, biomass burning and anthropogenic activities affect air quality and influence the climate through effects on solar radiation and clouds. Although many studies address such aerosol effects, there is a persistent difference in current estimates of the amount of aerosols in the atmosphere across observations and complex climate models. This study documents the data differences for aerosol amounts, including new estimates from climate‐model simulations and satellite products. We quantify considerable differences across aerosol amount estimates as well as regional and seasonal variations of extended and new data. Further, this study addresses the question to what extent complex climate models have improved over the past decades in light of observational uncertainty.
    Description: Key Points: Present‐day patterns in aerosol optical depth differ substantially between 94 modern global data sets. The range in spatial means from individual satellites is −11% to +17% of the multi‐satellite mean. Spatial means from climate model intercomparison projects fall within the satellite range but strong regional differences are identified.
    Description: Hans‐Ertel‐Center for Weather Research
    Description: Collaborative Research Centre 1211
    Description: Max‐Planck‐Institute for Meteorology
    Keywords: ddc:551.5
    Language: English
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  • 8
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    Assessing Volcanic Controls on Miocene Climate Change (2022)
    Details
    Publication Date: 2022-03-25
    Description: The Miocene period saw substantially warmer Earth surface temperatures than today, particularly during a period of global warming called the Mid Miocene Climatic Optimum (MMCO; ∼17–15 Ma). However, the long‐term drivers of Miocene climate remain poorly understood. By using a new continuous climate‐biogeochemical model (SCION), we can investigate the interaction between volcanism, climate and biogeochemical cycles through the Miocene. We identify high tectonic CO2 degassing rates and further emissions associated with the emplacement of the Columbia River Basalt Group as the primary driver of the background warmth and the MMCO respectively. We also find that enhanced weathering of the basaltic terrane and input of explosive volcanic ash to the oceans are not sufficient to drive the immediate cooling following the MMCO and suggest that another mechanism, perhaps the change in ocean chemistry due to massive evaporite deposition, was responsible.
    Description: Plain Language Summary: The Miocene period was much warmer than today, with the Mid Miocene Climatic Optimum (MMCO, roughly 17–15 million years ago) especially warm. Due to the high surface temperatures, comparisons to projected climatic conditions as a result of anthropogenic climate change have been drawn. However, the drivers of climate during the Miocene are not well understood. By using a new type of climate model, we investigate the impact volcanic eruptions had on the period, and link the extreme warmth of the MMCO with greenhouse gas release from the eruption of the Columbia River Basalts Group (CRBG). We find weathering of the CRBG does not explain the cooling at the end of the MMCO, and so discuss other potential explanations such as evaporite deposition.
    Description: Key Points: A new climate‐biogeochemical model allows investigation of drivers of climate change in the Miocene. Columbia River Basalt Group (CRBG) degassing is sufficient to have caused the Mid Miocene Climatic Optimum (MMCO). Weathering of CRBG insufficient to drive cooling after the MMCO. This may be linked to evaporite deposition and changes to marine chemistry.
    Description: UK Natural Environment Research Council
    Description: French Research Agency (ANR)
    Keywords: ddc:551
    Language: English
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  • 9
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    An Image Segmentation Approach for the Detection of Small-scale Magnetic Anomalies (2022)
    Details
    Publication Date: 2022-03-25
    Description: Due to the still enormous burden of unexploded ordnance (UXO) in the subsurface worldwide, the safe recovery of a wide variety of buried weapons and ammunition requires efficient and reliable detection methods. Using a deep learning approach applied to magnetic field data distributed areal along the surface, we aim to achieve a more accurate localization of UXO and small magnetically effective objects in general by detecting the specific signature of their magnetic anomaly. To investigate the applicability of this approach, we developed a deep convolutional neural network that performs image segmentation in different potential measurement scenarios. In this process, the sought small-scale target signals should be distinguished from different background fields containing, e.g., several types of noise. For this purpose, extensive synthetic data sets were generated first using numerical simulations of the magnetic dipole fields of multiple objects. The resulting multi-dipole scenarios and corresponding masks are then passed to the network, which is trained on a test and validation set to produce a representative model for the trained simulation examples. At the end of the training process, this model is supposed to be able to predict yet unknown examples from an evaluation set. Subsequently, the prediction quality of the resulting model needs to be analyzed to fine-tune the parameters of the assumed network architecture or even the architecture itself. The poster we present deals with the generation and preprocessing of appropriate training data, the applied network architecture, and preliminary results of the first evaluation stages.
    Description: poster
    Language: English
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  • 10
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    Faulting and Magmatic Accretion Across the Overlapping Spreading Center Between Vance Segment and Axial South Rift, Juan de Fuca Ridge (2022)
    Details
    Publication Date: 2022-03-24
    Description: Plate divergence along mid‐ocean ridges is accommodated through faulting and magmatic accretion, and, at overlapping spreading centers (OSC), is distributed across two curvilinear overlapping ridge axes. One‐meter resolution bathymetry acquired by autonomous underwater vehicles, combined with distribution and ages of lava flows, is used to: (a) analyze the spatial and temporal distribution of flows, faults, and fissures in the OSC between the distal south rift zone of Axial Seamount and the Vance Segment, (b) locate spreading axes, (c) calculate extension, and (d) determine the proportion of extension accommodated at the surface by faults and fissures versus volcanic extrusion over a period of ∼1300–1450 years. Our study reveals that in the recent history of the ridges, extension over a distance of 14 km across the Axial/Vance OSC was asymmetric in proportion and style: faults and fissures across 1–2 km of the Vance axial valley accommodated ∼3/4 of the spreading, whereas dike‐fed eruptions contributed ∼1/4 of the extension and occurred across 4 km of the south rift of Axial Seamount.
    Description: Plain Language Summary: Along mid‐ocean ridges, oceanic plates separate through the formation and growth of faults and the emplacement of dikes supplying lava flows. Where segments overlap in a zone of separation, these processes are distributed along two spreading axes separated by 2–30 km kilometers. We combine 1‐m resolution bathymetry collected by autonomous underwater vehicles and the age of large lava flows to (a) analyze the distribution of faults and lava flows where Axial Seamount overlaps with the Vance Segment, (b) define the current plate boundary, (c) calculate the speed of plate separation, and (d) determine the proportion and locations of fault extension versus flow emplacement. Our study shows that during the last ∼1300–1450 years, fault formation and growth along the Vance Segment are the main contributor to plate separation. In contrast, the emplacement of dikes and lava flows along Axial Seamount account only for ∼1/4 of the plate separation.
    Description: Key Points: Autonomous underwater vehicle mapping of an overlapping spreading center reveals the proportion of faulting and eruptions that occurred during the last ∼1300–1450 years. Faulting at the Vance Segment accommodates ∼3/4 of the spreading and magmatic accretion along Axial Seamount south rift accounts for ∼1/4. The spreading axis is 〈250 m wide along the Vance Segment but ∼4 km wide along the south rift of Axial Seamount.
    Description: David and Lucile Packard Foundation (PF) http://dx.doi.org/10.13039/100000008
    Keywords: ddc:551.8 ; ddc:551.13
    Language: English
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  • 11
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    Rock Glacier Characteristics Under Semiarid Climate Conditions in the Western Nyainqêntanglha Range, Tibetan Plateau (2022)
    Details
    Publication Date: 2022-03-24
    Description: Rock glaciers are receiving increased attention as a potential source of water and indicator of climate change in periglacial landscapes. They consist of an ice‐debris mixture, which creeps downslope. Although rock glaciers are a wide‐spread feature on the Tibetan Plateau, characteristics such as its ice fraction are unknown as a superficial debris layer inhibits remote assessments. We investigate one rock glacier in the semiarid western Nyainqêntanglha range (WNR) with a multi‐method approach, which combines geophysical, geological and geomorphological field investigations with remote sensing techniques. Long‐term kinematics of the rock glacier are detected by 4‐year InSAR time series analysis. The ice content and the active layer are examined by electrical resistivity tomography, ground penetrating radar, and environmental seismology. Short‐term activity (11‐days) is captured by a seismic network. Clast analysis shows a sorting of the rock glacier's debris. The rock glacier has three zones, which are defined by the following characteristics: (a) Two predominant lithology types are preserved separately in the superficial debris patterns, (b) heterogeneous kinematics and seismic activity, and (c) distinct ice fractions. Conceptually, the studied rock glacier is discussed as an endmember of the glacier—debris‐covered glacier—rock glacier continuum. This, in turn, can be linked to its location on the semiarid lee‐side of the mountain range against the Indian summer monsoon. Geologically preconditioned and glacially overprinted, the studied rock glacier is suggested to be a recurring example for similar rock glaciers in the WNR. This study highlights how geology, topography and climate influence rock glacier characteristics and development.
    Description: Plain Language Summary: Climate change has begun to impact all regions of our planet. In cold regions, such as high‐mountain areas, rising temperatures lead to massive melting of glaciers. Besides this evident loss of ice, permafrost, a long‐term ice resource hidden in the subsurface, has started to thaw. Rock glaciers as visible permafrost‐related landforms consist of an ice‐debris mixture, which makes them creep downslope. Due to this movement and their recognizable shape, rock glaciers are permafrost indicators in high‐mountain areas. We investigate one rock glacier in the western Nyaingêntanglha Range (Tibetan Plateau) using field and remote sensing methods to understand its development and to know the current state of its ice core. Our main outcome is, that the heterogeneous creeping behavior, the properties of the debris cover as well as the internal distribution of ice are the results of a continuous development from a glacier into today's rock glacier. In particular, the high ice content in particular sections points to such a glacial precondition. The debris layer covering the internal ice attenuates the effect of climate warming. This makes the rock glacier and similar rock glaciers found in the northern part of the mountain range important future water resources for the semiarid region.
    Description: Key Points: Geophysical and remote sensing methods in concert reveal the morphostructure, ice fraction, and kinematics of the studied rock glacier. Rock glacier characteristics are controlled by geology, topography and climate on the Tibetan Plateau. The studied rock glacier is conceptually interpreted as the endmember of a glacier—debris‐covered glacier—rock glacier continuum.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.31 ; ddc:555
    Language: English
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  • 12
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    Effects of CO2 and Ocean Mixing on Miocene and Pliocene Temperature Gradients (2022)
    Details
    Publication Date: 2022-03-28
    Description: Cenozoic climate changes have been linked to tectonic activity and variations in atmospheric CO2 concentrations. Here, we present Miocene and Pliocene sensitivity experiments performed with the climate model COSMOS. The experiments contain changes with respect to paleogeography, ocean gateway configuration, and atmospheric CO2 concentrations, as well as a range of vertical mixing coefficients in the ocean. For the mid‐Miocene, we show that the impact of ocean mixing on surface temperature is comparable to the effect of the possible range in reconstructed CO2 concentrations. In combination with stronger vertical mixing, relatively moderate CO2 concentrations of 450 ppmv enable global‐mean surface, deep‐water, and meridional temperature characteristics representative of mid‐Miocene Climatic Optimum (MMCO) reconstructions. The Miocene climate shows a reduced meridional temperature gradient and reduced seasonality. In the case of enhanced mixing, surface and deep ocean temperatures show significant warming of up to 5–10°C and an Arctic temperature anomaly of 〉12°C. In the Pliocene simulations, the impact of vertical mixing and CO2 is less important for the deep ocean, which we interpret as a different sensitivity dependence on the background state and mixed layer dynamics. We find a significant reduction in surface albedo and effective emissivity for either a high level of atmospheric CO2 or increased vertical mixing. Our mixing sensitivity experiments provide a warm deep ocean via ocean heat uptake. We propose that the mixing hypothesis can be tested by reconstructions of the thermocline and seasonal paleoclimate data indicating a lower seasonality relative to today.
    Description: Plain Language Summary: Cenozoic climate changes have been associated with tectonic changes and altered atmospheric CO2 concentrations. Here, we present Miocene and Pliocene computer simulations where we changed paleogeography, ocean gateways, and atmospheric CO2 concentrations as well as vertical mixing in the ocean. We show that the effect of ocean mixing on temperature is comparable to the respective effect of a possible range of CO2 concentrations. In combination with stronger vertical mixing, relatively moderate CO2 concentrations of 450 ppmv allow surface and deep‐water temperatures representative for reconstructions of the climate optimum of the mid‐Miocene. In the Pliocene simulations, the influence of vertical mixing and CO2 is less important than in the Miocene. We provide a possible mechanism of ocean heat absorption, albedo, and emissivity changes including a deeper oceanic mixing layer and a lower seasonality in the Miocene compared to today.
    Description: Key Points: Miocene experiment with standard mixing and atmospheric CO2 of 600 ppm captures large‐scale temperature characteristics of the mid‐Miocene. With enhanced ocean mixing the temperature characteristics and meridional temperature gradient can be reproduced with a CO2 level of 450 ppm. Miocene shows a strong warming at polar latitudes and reduced seasonality, vertical mixing, and CO2 are less important for the Pliocene.
    Description: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) http://dx.doi.org/10.13039/501100003207
    Description: Helmholtz Association (亥姆霍兹联合会致力) http://dx.doi.org/10.13039/501100009318
    Description: Helmholtz Climate Initiative RE‐KLIM
    Keywords: ddc:550.78
    Language: English
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  • 13
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    Zur nachhaltigen Nutzung von Hochmooren als Tiefumbruchkultur (2022)
    Details
    Publication Date: 2022-04-19
    Description: Die Nutzung landwirtschaftliche Nutzung der Hochmoore führt zu hohen Freisetzungsraten an Treibhausgasen. Gegenüber der Deutschen Hochmoorkultur (Grünland auf Hochmoor) lassen sich die Freisetzungsraten durch Tiefumbruch verringern. Ein Torfverlust von 1 cm entspricht bei den hier durchgeführten Berechnungen einer Freisetzung von ca. 25 t CO2/ha/a. Die geringsten Freisetzungsraten von 2,5 t CO2/ha/a werden bei als Grünland genutzten Sandmischkulturen, besandeten Hochmooren (ohne Einp ügen von Torfen) und bei Baggerkuhlungen erwartet. Die hohen Torfverluste in den ersten Jahren bei der Anlage einer Sandmischkultur lieÿen sich vermeiden, wenn anfangs nur geringere Torfanteile in die Krume gelangen (6-8%), wie bei der Tiefp ugsanddeckkultur, die bisher für Niedermoore getestet wurde. Durch Messungen der aktuellen Freisetzung von Treibhausgasen auf Tiefumbruch ächen sind diese Berechnungen zu überprüfen. Liegen Torfe im Unterboden ganzjährig im Wasser, dann sind Torfverluste auszuschlieÿen. Eine langfristige landwirtschaftliche Nutzung ist mit der Anlage von Tiefumbruchkulturen möglich. Ein vollständiger Erhalt der Torfe ist nur durch eine Wiedervernässung zu erzielen, entweder Nutzungsaufgabe und Herrichtung als Naturschutz äche oder Paludikultur, beide sicherlich nur auf geringeren Flächenanteilen.
    Description: report
    Language: German
    Type: doc-type:conferenceObject
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  • 14
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    Blaubeuren, Cloppenburg, and Machtenstein—Three recently recognized H‐group chondrite finds in Germany with distinct terrestrial ages and weathering effects (2022)
    Details
    Publication Date: 2022-03-29
    Description: In the last 7 years, three meteorites (Blaubeuren, Cloppenburg, and Machtenstein) found in Germany were identified as chondrites. Two of these rocks had been recovered from the impact sites decades ago but were not considered to be meteorites. The aim of this study is to fully characterize these three meteorites. Based on the compositional data on the silicates, namely olivine and low‐Ca pyroxene, these meteorites fit nicely within the H‐group ordinary chondrites. The brecciated texture of Blaubeuren and Cloppenburg (both H4‐5) is perfectly visible, whereas that of Machtenstein, officially classified as an H5 chondrite, is less obvious but was detected and described in this study. Considering chondrites in general, brecciated rocks are very common rather than an exception. The bulk rock degree of shock is S2 for Blaubeuren and Machtenstein and S3 for Cloppenburg. All samples show significant features of weathering. They have lost their original fusion crust and more than half (W3) or about half (W2‐3) of their original metal abundances. The oxygen isotope compositions of the three chondrites are consistent with those of other H chondrites; however, the Cloppenburg values are heavily disturbed and influenced by terrestrial weathering. This is supported by the occurrence of the very rare hydrated iron phosphate mineral vivianite (Fe2+Fe2+2[PO4]2·8H2O), which indicates that the chondrite was weathered in a very wet environment. The terrestrial ages of Blaubeuren (~9.2 ka), Cloppenburg (~5.4 ka), and Machtenstein (~1.8 ka) show that these chondrites are very similar in their degree of alteration and terrestrial age compared to meteorite finds from relatively wet terrestrial environments. They still contain abundant metal, although, as noted, the oxygen isotope data indicate substantial weathering of Cloppenburg. The bulk compositions of the three meteorites are typical for H chondrites, although terrestrial alteration has slightly modified the concentrations, leading in general to a loss of Fe, Co, and Ni due to preferential alteration of metals and sulfides. As exceptions, Co and Ni concentrations in Machtenstein, which has the shortest terrestrial age, are typical for H chondrites. The chemical data show no enrichments in Ba and Sr, as is often observed in different meteorite groups of desert finds.
    Description: European Regional Development Fund http://dx.doi.org/10.13039/501100008530
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:549.112
    Language: English
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  • 15
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    Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand: A Core‐Log‐Seismic Integration Study (2022)
    Details
    Publication Date: 2022-03-29
    Description: Although submarine landslides have been studied for decades, a persistent challenge is the integration of diverse geoscientific datasets to characterize failure processes. We present a core‐log‐seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post‐failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly‐reflective and chaotic seismic unit. This chaotic unit is characterized by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within the landslide deposits is a widespread “Intra‐debris Reflector”, previously interpreted as the landslide's basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10–15 m above the Intra‐debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre‐conditioning the slope to failure. Additional pre‐conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core‐log‐seismic integration approaches for investigating basal shear zone development in submarine landslides.
    Description: Plain Language Summary: Submarine landslides move enormous amounts of sediment across the seafloor and have the potential to generate damaging tsunamis. To understand how submarine landslides develop, we need to be able to image and sample beneath the seafloor in regions where landslides have occurred. To image beneath the seafloor we generate sound waves in the ocean and record reflections from those waves, enabling us to produce “seismic images” of sediment layers and structures beneath the seafloor. We then use scientific drilling to sample the sediment layers and measure physical properties. In this study, we combine seismic images and drilling results to investigate a submarine landslide east of New Zealand's North Island. Drilling next to the landslide revealed a ∼25 m‐thick layer of sediment (from ∼75–95 m below the seafloor) that has strong variations in sediment strength and density. We infer that intervals of relatively low strength within this layer developed into the main sliding surface of the landslide. Additionally, results from within the landslide suggest that the process of landslide emplacement has induced a zone of weak sediments closer to the seafloor. Our study demonstrates how combining seismic images and drilling data helps to understand submarine landslide processes.
    Description: Key Points: We integrate scientific drilling data with seismic reflection data to investigate the submarine Tuaheni Landslide Complex. Basal shear zone of the landslide likely exploited a relatively low shear strength interval within an older (buried) mass transport deposit. Landslide emplacement seems to have induced an additional weak zone that is shallower than the interpreted base of the landslide deposit.
    Description: Marsden Fund (Royal Society of New Zealand Marsden Fund) http://dx.doi.org/10.13039/501100009193
    Description: European Consortium for Ocean Research Drilling
    Description: International Ocean Drilling Program, Science Support Program
    Description: New Zealand Ministry for Business Innovation and Employment
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://doi.pangaea.de/10.1594/PANGAEA.928073
    Keywords: ddc:622.15 ; ddc:551
    Language: English
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  • 16
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    Seismische Methoden in der Lagerstättenforschung (2022)
    In:  SUB Göttingen | 4 Z NAT 2176:16
    Details
    Publication Date: 2022-02-28
    Description: Der Beitrag gibt eine Einführung zur Entwicklungsgeschichte der Explorationsseismik.
    Description: report
    Description: DFG, SUB Göttingen
    Keywords: 622.1592 ; Geophysikalische Verfahren {Lagerstättenkunde} ; Geophysikalische Verfahren {Kohlenwasserstofflagerstätten} ; Explorationsseismik ; FID-GEO-DE-7
    Language: German
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  • 17
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    Die Bedeutung der Stoff-Konstanten natürlicher Gesteine für Bauwesen, Geologie und Bergbau (2022)
    In:  SUB Göttingen | 8 MIN I,1230:24
    Details
    Publication Date: 2022-02-28
    Description: Unter Heranziehen eigener Forschungsergebnisse und zahlreicher Einzelarbeiten aus den Gebieten Bauwesen, Geologie und Bergbau, wird auseinandergesetzt, wie sich aus der einfachen Werkstoffprüfung an Naturstein eine Arbeitsrichtung unter Zusammenfassung physikalischer, mechanischer, mineralogischer und geologischer Arbeitsmethoden entwickelt hat, die man als „Gesteinstechnik“ bezeichnen könnte. Wie für eine Baukonstruktion die Statik nicht ohne Kenntnis der Materialkonstanten ausgearbeitet werden kann, so sind andererseits unter Zuhilfenahme der Statik und der markscheiderischen Meßverfahren die Probleme des Gebirgsdruckes nur zu lösen, wenn — unter Beachtung der Stoffkonstanten der das Gebirge aufbauenden Schichten — die Gesetze der technischen Mechanik richtig angewendet werden. Der Modellversuch kann uns erst dann vorwärts bringen, wenn wir durch Kenntnis der Stoffkonstanten des Gebirges das Modell so aufbauen können, daß die einzelnen Teile im Maßstab wohl kleiner, aber im Verhältnis der Festigkeits- und Verformungseigenschaften wirklichkeitstreu sind. Bei sinnvoller Zusammenarbeit der naturwissenschaftlichen und technischen Richtungen, deren Gebiete hier angeschnitten wurden, können die wissenschaftlichen Erkenntnisse aus der Gesteinstechnik, angewandt auf praktische Fragen des Bauwesens, der Geologie und des Bergbaues, manches Problem der Lösung näherbringen.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 552.06 ; Technische Gesteinskunde ; Ingenieurgeologische Bewertung von Gesteinen und Sedimenten als Baugrund und Baustoff ; Geomechanik ; FID-GEO-DE-7
    Language: German
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  • 18
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    Festschrift Max Bauer zum siebzigsten Geburtstage gewidmet (2022)
    Schweizerbart'sche Verlagsbuchhandlung, Stuttgart
    In:  SUB Göttingen | 8 MIN I, 1220:Beilage-Bd 39
    Details
    Publication Date: 2022-02-28
    Description: Die Festschrift zum siebzigsten Geburtstage des Mineralogen Max Bauer (1844-1917), langjähriger, unermüdlicher und unparteiischer Redakteur des Neuen Jahrbuchs und des Centralblatts für Mineralogie, Geologie und Paläontologie, enthält 22 Beiträge zur Mineralogie und Petrologie von seinen Mitarbeitern, Freunden und Schülern.
    Description: commemorativepublication
    Description: DFG, SUB Göttingen
    Keywords: 549 ; Festschriften {Mineralogie} ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 568
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  • 19
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    Neue geologische Beobachtungen bei Stadtilm (2022)
    In:  SUB Göttingen | 8 Z NAT 2662:8
    Details
    Publication Date: 2022-02-28
    Description: Feinstratigraphische, tektonische und allgemein-geologische Beobachtungen werden mitgeteilt. Im Röt lassen sich noch nicht alle charakteristischen Horizonte von Ostthüringen nachweisen. Im unteren Muschelkalk wurde eine Anzahl der von Jena bekannten Horizonte neu ermittelt, u. a. die Bänke d2, d3, fi, f4, die Schichten mit Myo. incurvata, die untere und obere Querplattungszone. Für andere, wie den konglomeratischen Wellenkalk, die Oolithbank ß und f3 werden neue Fundstellen angegeben. Die Oolithbank a läßt sich nicht klar festlegen. Die Terebratelzone ist in der Gesamtmächtigkeit nicht konstant, die Schaumkalkbänke wechseln in Stärke und teilweise auch Ausbildung. Der untere Muschelkalk von Stadtilm entspricht der Ostthüringer Ausbildung weitgehend, doch machen sich Abweichungen in der Mächtigkeit einzelner Stufen geltend. Im mittleren Muschelkalk fallen örtlich Zellenkalke und -dolomite auf. In mm ist auch der Gips in den oberflächennahen Gebieten meist ausgelaugt, was sich morphologisch auswirkt. Ein Profil des Überganges nach mo1 wird beschrieben. In mo2 mangelt es an besseren Aufschlüssen. Der untere Keuper nimmt größere Gebiete als bisher bekannt ein und zeigt typische Gesteinsausbildungen, u. a. den Guthmannshäuser Kalk. Diluviale Ablagerungen der Ilm sind stellenweise ziemlich mächtig - Alluvialer Kalktuff ist verbreitet bei Kl.-Hettstedt. Einige tektonische Bilder aus der Eichenberg— Saalfelder Störungszone werden beschrieben. Die südliche Remdaer Störungszone reicht bis zum Ilmtal, die nördliche findet möglicherweise ihre Fortsetzung weit nach NW hin. Auch rheinisch verlaufende Störungen sind wahrscheinlich. Ursache für „Abgänge“ an Muschelkalkhängen ist die Gleitbewegung auf den liegenden wasserstauenden Schichten. Strudeltaschen sind im Muschelkalk recht häufig. Als Füllung solcher Taschen und anderer Spalten spielen u. a. Kalkspatausscheidungen eine Rolle, die lokal auch oberflächlich in auffallenden Resten erhalten sind.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 554.3 ; Thüringen {Geologie} ; Stadtilm ; Geologie ; FID-GEO-DE-7
    Language: German
    Type: map
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  • 20
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    Ergebnisse geologischer Forschungen in Minas Geraes (Brasilien) (2022)
    Schweizerbart, Stuttgart
    In:  SUB Göttingen | 8 MIN I, 1220:SondBd 2
    Details
    Publication Date: 2022-02-28
    Description: Minas Geraes gehört seit alten Zeiten zu den Gegenden der Erde, die wegen ihres Mineralreichtums allgemein berühmt waren. Weitaus die größte Zahl der Veröffentlichungen über dieses Land beschäftigt sich mit den Bodenschätzen, mit einzelnen Lagerstätten, mit besonders interessanten Mineralien, während nur sehr wenige Autoren sich mit dem geologischen Bau einzelner Landesteile befaßt haben. Die vorliegende Arbeit präsentiert die geologischen Ergebnisse von Forschungsreisen durch die Region in den 1920-ziger Jahren mit dem Ziel, eine Übersicht über die großen Zusammenhänge zu gewinnen und einen Rahmen zu schaffen, in den sich ältere und künftige Spezialuntersuchungen einfügen lassen.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 558 ; Brasilien und Uruguay {Geologie} ; Minas Geraes ; Geologie ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 403, XXVII
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  • 21
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    Festband Reinhard Brauns (2022)
    Schweizerbart, Stuttgart
    In:  SUB Göttingen | 8 MIN I, 1220:Beilage-Bd 64
    Details
    Publication Date: 2022-02-28
    Description: Der Festband zum siebzigsten Geburtstag des Mineralogen Reinhard Brauns (1861-1937) enthält 44 Beiträge zur Kristallographie, Mineralogie, Petrographie, Geochemie und Lagerstättenkunde von seinen Freunden und Schülern sowie dem Verlag.
    Description: commemorativepublication
    Description: DFG, SUB Göttingen
    Keywords: 549 ; 548 ; 552 ; 553 ; Festschriften {Mineralogie} ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 850
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  • 22
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    Versteinerungen des Oberen Muschelkalks bei Ohrdruf als aufschlußreiche Dokumente für die Geschichte des deutschen Muschelkalkmeeres (2022)
    In:  SUB Göttingen | 8 MIN II, 2650:5
    Details
    Publication Date: 2022-02-28
    Description: Der Beitrag umfasst ein Referat über einige Versteinerungen des Oberen Muschelkalks bei Ohrdruf und soll ein Hinweis darauf sein, daß bestimmte Fossilien und gewisse Gesteinsformen in mo besonders aufschlußreiche Dokumente für die Geschichte des deutschen Muschelkalkmeeres sein können.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 560 ; Thüringen {Paläontologie} ; Trias {Stratigraphische Paläontologie} ; Oberer Muschelkalk ; Fossil ; FID-GEO-DE-7
    Language: German
    Type: map
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  • 23
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    Ist eine Ausbeutung der fast vergessenen sächsischen Vorkommen von Topas und Achat heute wirtschaftlich möglich? (2022)
    In:  SUB Göttingen | 8 MIN I,1230:22
    Details
    Publication Date: 2022-02-28
    Description: Der Beitrag gibt einen Überblick über eine wirtschaftliche Verwertbarkeit von sächsischen Schmucksteinvormkommen.
    Description: report
    Description: DFG, SUB Göttingen
    Keywords: 553.8 ; Regionale Vorkommen von Edelsteinen ; Sachsen ; Topas ; Achat ; Lagerstätte ; FID-GEO-DE-7
    Language: German
    Type: map
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  • 24
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    Scheinbare Großkolonien von Graptolithen (2022)
    In:  SUB Göttingen | 8 Z NAT 2662:8
    Details
    Publication Date: 2022-02-28
    Description: Der Beitrag liefert eine Betrachtung von 3 verschiedenen Graptolithenfunden.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 563 ; Stomochorda {Paläozoologie} ; Graptolithen ; FID-GEO-DE-7
    Language: German
    Type: map
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  • 25
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    Untersuchungen zur Bruchtektonik in der Zentralägäis (2022)
    Reimer, Berlin
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-02-16
    Description: Die vorliegende Arbeit soll einen Beitrag zur Erfassung und Analyse der postalpinen Bruchtektonik des zentralägäischen Raumes liefern. Das Arbeitsgebiet umfaßt Teile aller drei Stockwerke der alpidischen Helleniden, insbesondere der West- und Zentralhellenischen Decken. Das Bruchmuster mußte in zwei grundsätzlich verschiedenen Bereichen erfaßt werden - auf dem Festland und im Meer. Die seit einigen Jahren zur Verfügung stehenden Satellitenbilder ermöglichten eine flachendeckende Interpretation der Landgebiete des Untersuchungsareals. In wichtigen Teilgebieten wurden sie Luftbild-Auswertungen gegenübergestellt sowie durch Geländekontrollen überprüft. Dieser dreistufige Vergleich wurde für den Westteil des Untersuchungsgebietes, in der südöstlichen Argolis und der Lakonischen Halbinsel, im Zentrum auf der Insel Naxos und im Osten auf den Inseln Samos und Ikaria durchgefuhrt. Unter Berücksichtigung der Eigenheiten der verschiedenen Auswertungsmethoden konnten in der Satellitenbild-Auswertung eine große Anzahl der Lineationen bewertet und Bruchzonen von regionaler Bedeutung herausgefiltert werden. Für die vom Meer bedeckten Gebiete mußte das Bruchmuster aus der Morphologie des Meeresbodens, die sich in Isobathenkarten wiederspiegelt, gewonnen werden. Von großmaßstäbigen Seekarten ausgehend, konnten insbesondere der Schelfbereich und über diesen hinaus große Teile des Meeresbodens im Bereich der zentralägäischen Inselbrücke relativ detailliert dargestellt werden, über eine daraus entwickelte Hangneigungskarte wurden die sich auf dem Meeresboden abzeichnenden Bruchspuren erfaßt. Die Interpretationsergebnisse der verschiedenen Auswertungsmethoden werden für alle Teilgebiete der Region getrennt vorgestellt und verknüpft betrachtet. Danach zeigt das Bruchmuster im Einzelnen ein recht differenziertes Bild, doch lassen sich übergreifende Trends erkennen: Im Westen dominieren zwischen dem Ost-Peloponnes und dem Westrand des Kykladen-Plateaus Bruchzonen in der NNU/SSE-Richtung. östlich davon herrschen dagegen bis zur kleinasiatischen Küste Bruchzonen vor, die ENE/WSW bis NE/SW verlaufen. Im nordöstlichen Peloponnes und auf der Landbrücke von Korinth sowie im Bereich der Menderes-Gräben und auf Samos sind überwiegend E/W streichende Bruchzonen vertreten. Im Gegensatz zu bisher veröffentlichten neotektonischen Ergebnissen enthält das Bruchmuster auch innerhalb des südägäischen Bogens Blattverschiebungen… Ein relativ ausgeglichenes Spannungsfeld im Bereich des ägäischen Bogens legt neben Subduktion und back-arc basin eine weitere Beeinflussung der Kruste dieses Raumes nahe, die in der Westdrift der Arabischen Platte denkbar wäre.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 554.95 ; Strukturelle Erscheinungen {Strukturgeologie} ; Randmeere Atlantischer Ozean {Geologie} ; Ägäis ; Bruchtektonik ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 144
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  • 26
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    Karte der Zentral- und Südägäis - Bruchtektonik (2022)
    Berlin, Reimer
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-02-16
    Description: Die Bearbeitung der tektonischen Übersichtskarte der Zentral- und Südägäis beginnt mit der Klärung des Kartenzwecks, des Benutzerkreises und des Benutzungsvorganges. Aus der Feststellung, daß sich die Karte besonders an Geologen wendet, die der Darstellung sowohl Einzelinformationen entnehmen, als auch einen zusammenfassenden überblick über den tektonischen Bau der Region erhalten wollen, ergibt sich die Forderung nach einer detaillierten und trotzdem übersichtlich gestalteten Darstellung der tektonischen Baueinheiten und der Bruchstrukturen in Verbindung mit dem Relief. Es wird ein Gegenstandskatalog aufgestellt, der in der Karte möglichst zur Darstellung kommen soll. Die Inhaltselemente werden bezüglich ihrer Strukturformen im Grundriß, ihrer Sach- und Lagebeziehungen untereinander und zu den topographischen Elementen hin untersucht. Die Ergebnisse dieser Untersuchung lassen eine systematische Umsetzung der Inhaltselemente in die graphische Zeichensprache zu, wobei Objekt- und Zeichengesetzmäßigkeiten beachtet werden. So wird der optische Eindruck der Karte von den Land- und Meeresfarben gesteuert. Die gegensätzliche Wirkung der warmen und kalten Farben läßt eine Grobgliederung des Kartenbildes zu. Während dieser Gegensatz von Land und Meer und die Bruchstrukturen in Abhängigkeit von morphologischer Gestalt und Untergrund in der obersten Wahrnehmungsebene stehen, rücken die Einzelinformationen über absolute und relative Höhen- oder Tiefenlagen und über die differenzierte Gliederung der tektonischen Einheiten in den Hintergrund. Diese in Wahrnehmungsebenen gestufte Darstellung erleichtert dem Kartenbenutzer das Lesen der Karte. Wesentliches ist hervorgehoben, Unwesentliches zurückgedrängt. Die Herstellung der Karte wird durch den chronologischen Arbeitsablauf dargestellt.
    Description: report
    Description: DFG, SUB Göttingen
    Keywords: 526 ; Karten zur Tektonik ; Kartenentwurf {Kartographie} ; Ägäis-Gebiet ; Bruchtektonik ; Kartenentwurf ; Kartenherstellung ; FID-GEO-DE-7
    Language: German
    Type: map
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  • 27
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    Korngrößenverteilung und Schwermineralführung in den Flußsanden der Ziller (Tirol/Österreich) (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-14
    Description: Die Mineralgesellschaft eines Sandes wird in ihrem qualitativen Bestand vom Ausgangsmaterial im Liefergebiet bestimmt, die quantitative Zusammensetzung hängt dagegen weitgehend vom Transportmechanismus und der Länge des Transportweges ab. Die besondere Lage des untersuchten Gebietes in den kristallinen Schiefern der Tauernschieferhülle ermöglicht es, die Bindung der dort entstandenen Schwermineralgesellschaften an das Ausgangsgestein zu untersuchen. So wurden die rezenten Abtragungsprodukte im Einzugsgebiet der Ziller quantitativ und qualitativ auf den Mineralbestand hin untersucht. Alle Untersuchungen wurden mit Hilfe von mechanischen, optischen sowie röntgenographischen Methoden durchgeführt. Dabei wurde die konventionelle Methode der Schwermineraltrennung dahingehend verbessert, daß die Proben zentrifugiert und der Bodensatz eingefroren wurde...
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: Schwerminerale {Mineralogie} ; Granulometrie {Sedimentologie} ; Fluviatile Sedimentation {Geologie} ; Nördliche Ostalpen {Geologie} ; Schwerminaralanalyse ; Ziller ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 58
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  • 28
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    Die tertiäre Teleosteer-Fauna Neuseelands, rekonstruiert anhand von Otolithen (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-14
    Description: Diese Monographie behandelt die tertiäre neuseeländische Otolithen-Fauna vom Unter-Eozän bis ins Pliozän. 160 Arten werden beschrieben. Damit umfaßt die jetzt bekannte Otolithen-Fauna Neuseelands insgesamt 164 Arten. Anhand des Typus-Materials werden die in vorangegangenen Arbeiten aufgestellten Arten revidiert (FROST 1924, 1928, 1933 und STINTON 1957). 27 ihrer 31 validen Arten konnten wiedergefunden werden. 80 Arten werden als Neue beschrieben, 40 in offener Nomenklatur und 13 als konspezifisch mit rezenten Arten dieser Region. 9 neue Gattungen werden aufgestellt. Zum Vergleich werden mehr als 200 Otolithen rezenter Arten aus australisch-neuseeländischen Gewässern und der Tiefsee abgebildet. In vielen Fällen wird die Systematik der behandelten rezenten und fossilen Fische erörtert. Die hier beschriebene fossile Fauna kann bei weitem noch nicht als vollständig angesehen werden. Im Anschluß an den systematischen Teil der Monographie wird eine biologische Rekonstruktion der Fauna versucht. Erste biostratigraphische Auswertungen, basierend auf der Otolithen-Fauna dieser Region, werden erörtert; desgleichen palökologische und paläobiogeographische (Faunenwanderungen von und nach Neuseeland; Verlandung der Indischen Meeresstraße; Öffnung der Antarktisch-Australischen Meeresstraße) Schlußfolgerungen.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 567 ; Neuseeland {Paläontologie} ; Osteichthyes {Paläozoologie} ; Tertiär {Stratigraphische Paläontologie} ; Tertiär ; Knochenfische ; Otolith ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 211
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  • 29
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    Geologische und petrographische Untersuchungen am Ostrand des Akapol-Batholithen im Zentral-Alborz/Iran mit besonderer Berücksichtigung der radioaktiven Minerale (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-14
    Description: Der Akapol-Batholith des zentralen Alborz-Gebirges zeichnet sich an der östlichen Seite mit seinen gangförmigen Differentiationsprodukten durch eine Reihe von radioaktiven Anomalien (bis 9ooo cps) im Mejel-Tal aus. Dieses Gebiet wurde geologisch kartiert sowie petrographisch, radiometrisch und geochemisch untersucht. Das Massiv ist von seinem Gesteinsrahmen im Mejel-Tal durch eine konkordante kontaktmetamorphe Marmorzone scharf abgegrenzt. Darauffolgende, konkordante, paläozoische, quarzitische Sandstein-/Marmor-Wechselfolgen, die von einer schwachen Regionalmetamorphose überprägt sind, werden infolge der flachgründigen Unterlagerung des Akapol-Batholithen im Guret-Tal von einer Kontaktmetamorphose erfaßt und sind dort in Kalksilikatfels und Andalusit-Hornfelsschiefer umgewandelt. Über den obengenannten sandigen, kalkigen bis tonigen Gesteinen lagern konkordant jungpaläozoische, organogene Kalkgesteine. Petrologisch wird der Akapol-Batholith im Mejel-Tal in folgende drei Intrusionsphasen aufgeteilt: — die Intrusion des Batholith-Körpers, bestehend aus Monzodiorit und Monzonit, — die Intrusion der Randzone, bestehend aus Syenit und Alkalifeldspatsyenit, — die Intrusion der Gänge. Hier sind folgende Abfolgen vertreten: Ägirinalkaligranit, Granitaplit, Alkalifeldspataplit, Alkalifeldspatquarzsyenit, Monzonitporphyr und Lamprophyr. Geologisch, petrographisch und petrochemisch wurden die magmatischen Zusammenhänge zwischen den drei Intrusionsphasen untersucht. Dabei stellte sich heraus, daß alle drei Intrusionen als Differentiationsfolge alkalischer Magmen aufzufassen sind, die vom Körper zum Rand des Batholithen und weiter in den Gängen sich durch Kristallisations-Differentiation von basisch-intermediären Gliedern zu sauren Differentiaten entwickeln. Die SEE-Vertei1ung in den magmatischen Gesteinen und in ihren gesteinsbildenden Mineralien unterstützt die Aussage über die obengenannte magmatische Spezialisierung. Die Verteilung von Uran und Thorium spiegelt sich ebenfalls in dieser Differentiationsabfolge wider. Der Th-Gehalt nimmt vom Körper des Batholithen (9 ppm) zu der Randzone hin (42 ppm) zu. Bei zunehmender Differentiation in den Ganggesteinen erreichen Uran und Thorium ihre höchste Konzentration. Als Hauptträger der Radioaktivität im Mejel-Tal treten die Ägirinalkaligranite mit durchschnittlich 211 ppm U und 2452 ppm Th in Erscheinung. Neben den submikroskopischen Akzessorien mit ihrem hohen Anteil an U und Th in den gesteinsbildenden Mineralien wurden als Träger des Urans Uranpyrochlor mit einem Gehalt von durchschnittlich 15,67 UO2 Gew.-% und des Thoriums Thorit mit einem Gehalt von 44,31 ThO2 Gew.-% in den Ägirinalkaligranitgängen identifiziert. Aufgrund der Flußsediment-Untersuchungen wurde festgestellt, daß die akzessorischen Mineralien wie Zirkon, Monazit, Apatit etc. keine nennenswerten Gehalte an U und Th aufweisen. Die Untersuchungen in den magmatischen Gesteinen, ihren Verwitterungsprodukten und in Oberflächengewässern deuten auf eine schwache bzw. beginnende Verwitterung der radioaktiven Minerale im Mejel-Tal hin. Volumenmäßig spielen die in Gängen auftretenden, sauren Differentiate keine größere Rolle. Deshalb muß das Vorkommen von Lagerstätten des Urans oder des Thoriums als sehr unwahrscheinlich angesehen werden.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 555 ; Iran {Geologie} ; Plutonismus {Geologie} ; Granitische Gesteine {Petrologie} ; Radioaktive Minerale ; Batholith ; Uranmineralien ; Thoriummineralien ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 71
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  • 30
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    Spurenanalyse als Hilfsmittel bei der geochemischen Untersuchung der Genese bolivianischer Sn-Lagerstätten (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-15
    Description: Die Diskussion der Möglichkeiten und Grenzen der Funkenquellenmassenspektrometrie und Neutronenaktivierungsspektrometrie bei der Analyse von Kassiterit-(Sn02)-Proben hat gezeigt, daß mit Hilfe dieser beiden Methoden routinemäßig 23 Elemente quantitativ bestimmt werden können. Aus dem Verhalten der Elemente W, Ta, Hf, Nb, Zr, Ga, Fe und Sc in Proben der einzelnen Lagerstätten ist zu erkennen, daß diese Elemente zu einer Deutung der Genese der Vorkommen herangezogen werden können. Ta, Hf, Nb und Zr zeigen die höchsten Gehalte in Kassiteriten pegmatitischen Ursprungs. Zinnsteine aus den hydrothermalen subvulkanischen Lagerstätten im Süden Boliviens sind dagegen im allgemeinen arm an diesen Elementen. W, Ga, Fe und Sc zeigen ein antagonistisches Verhalten. Kassiterite aus Pegmatiten, Sn-Graniten und deren Seifen zeigen Hf/Zr-Verhältnisse, die im Mittel etwa um den Faktor 10 größer sind als die aus anderen Vorkommen. Im Zuge der Remobilisation scheinen diese Zinnsteine Hf und Zr zu verlieren, wobei die Abnahme von Hf schneller erfolgt als die von Zr. Damit verbunden ist eine Abnahme des Hf/Zr-Verhältnisses. Daneben können diese beiden Elemente durch Wechselwirkungen zwischen hydrothermalen Lösungen und dem Nebengestein in den Lösungen angereichert werden, wobei keine Veränderung im Hf/Zr-Verhältnis zu beobachten ist. Der Einbau von W in das Kassiteritgitter scheint begrenzt zu werden. Aus dem Verhalten von Zinnsteinen aus verschiedenen Sn-Provinzen in W/Sn-W/Ta-Variationsdiagrammen lassen sich vom Lagerstättentyp abhängige Sättigungsgrenzen für den W-Gehalt in Kassiterit ablesen. Daraus kann geschlossen werden, daß der Einbau von W nicht allein durch kristallchemische Parameter kontrolliert wird. Es wird vermutet, daß die W-Grenzgehalte hauptsächlich durch die unterschiedliche Löslichkeit von Wolframit in der jeweiligen erzbringenden fluiden Phase gekennzeichnet sind. Aus dem Verhalten aller untersuchten bolivianischen Lagerstätten kann geschlossen werden, daß die physikalisch-chemischen Prozesse, die unabhängig vom geologischen Alter zur Erzbildung geführt haben, entscheidende Bedeutung für die Spureneiementverteilung haben. Aufgrund der geochemischen Beobachtungen lassen sich diese Lagerstätten in zwei Gruppen unterteilen, die sich grundlegend in der Art der erzbringenden fluiden Phase unterscheiden.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 551.9 ; Zinnerze {Lagerstättenkunde} ; Bolivien und Paraguay {Rohstoffgeologie} ; Untersuchungsverfahren und Ergebnisse {Mineralogie: Erzminerale} ; Spektroskopische Verfahren {Geochemie} ; Bolivien ; Zinnlagerstätte ; Zinnstein ; Spurenanalyse ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 79
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    Konzeption des geplanten Berliner Sonderforschungsbereiches "Geowissenschaftliche Probleme arider Gebiete" (2022)
    Berlin, Reimer
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-19
    Description: Die geowissenschaftliche Problematik der Trockengebiete beruht vor allem auf dem Konflikt, der sich aus der lebensfeindlichen Klimasituation und dem geowissenschaftlichen Gesamtpotential dieser Gebiete ergibt: Große, weitgehend ungenutzte Flächen, ein normalerweise nur randlich bekanntes Rohstoffpotential und begrenzte Grundwasservorräte kennzeichnen eine spezifische Problematik, deren wissenschaftliche Erforschung von großer praktischer Bedeutung für die ständig anwachsende Erdbevölkerung bei gleichzeitiger Verknappung von Rohstoffen und Nahrungsmitteln sein wird. Aridität ist Folge spezifischer klimatischer Situationen. Das Klima war während der Erdgeschichte einem ständigen Wandel unterworfen. Es kennzeichnet lediglich eine augenblickliche Situation und deren geowissenschaftliche Prozesse. Erst vor dem Hintergrund der geologischen Gesamtentwicklung des jeweiligen Gebietes wird der eingangs skizzierte Konflikt jedoch deutlich, der beispielsweise in konkurrierenden Nutzungsansprüchen von Landwirtschaft und Bergbau in bezug auf begrenzte Wasserresourcen bestehen kann. Die geowissenschaftliche Erforschung heute arider Gebiete muß die jüngere Klimageschichte erfassen, die wesentlich ist für die augenblickliche Grundwassersituation sowie für überprägende Vorgänge der Landschaftsentwicklung und der Bodenbildung. Daneben muß sie ein klares Bild von der geologischen Gesamtentwicklung des jeweiligen Gebietes erbringen, um so Vorstellungen zum Potential an Rohstoffen, Grundwasser und Böden zu ermöglichen. Das Nebeneinander großer ungenutzter Flächen, nur teilweise bekannter Rohstoffvorräte und endlicher Grundwasservorkommen ist in den ariden Gebieten der Erde vor allem realisiert im Bereich der großen kratonalen Becken des nördlichen Afrika und Arabiens sowie des südlichen Afrika und Australiens. Unsere als exemplarisch zu verstehenden Untersuchungen sollten ihre Muster demzufolge in diesen Gebieten suchen, wobei sich zunächst Nordafrika aus naheliegenden Gründen anbietet. Da intramontane Becken der ariden Gebiete Innerasiens und Amerikas eine teilweise ähnliche Problematik erwarten lassen, sollten im Rahmen gezielter vergleichender Fragestellungen auch vergleichende Untersuchungen möglich sein. Ebenso sollten Vergleiche möglich sein, die die Deutung fossiler Umlagerungsprozesse im kontinentalen Bereich am rezenten Beispiel erlauben und zwar unabhängig vom derzeitigen Klima. In bezug auf die zunächst angestrebte Bearbeitung von Becken Nordafrikas schließlich empfiehlt es sich, eine tektonische Bearbeitung des Nordrandes der Saharatafel einzubeziehen, weil ein Teil des Rohstoffpotentials der saharischen Becken abhängig ist von Bewegungsvorgängen am Tafelrand. Die Untersuchungen sollen dazu dienen, aus geowissenschaftlicher Sicht die Nutzungsmöglichkeiten und die Nutzungsgrenzen heute arider Gebiete an geeigneten Beispielen aufzuzeichnen. Darüber hinaus werden die für dieses Ziel zu erarbeitenden Forschungsergebnisse wesentliche Beiträge zur Klärung diverser geowissenschaftlicher Fragen in den Untersuchungsgebieten erbringen.
    Description: report
    Description: DFG, SUB Göttingen
    Keywords: 550 ; Wissenschaftsorganisation und -pflege {Geologische Wissenschaften} ; FID-GEO-DE-7
    Language: German
    Type: map
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    Petrographische und geochemische Untersuchungen an drei Graniten im Nationalpark Bayerischer Wald (2022)
    Berlin, Reimer
    In:  Herausgeberexemplar | Herausgeberexemplar
    Details
    Publication Date: 2022-01-19
    Description: Im Mittelpunkt der Betrachtungen steht ein im Östlichen Teil des Nationalparks Bayerischer Wald auftretender Granitkomplex, der sich aus drei Granittypen zusammensetzt, die im Verlauf der varistischen Orogenese intrudierten: Älterer Finsterauer Kristallgranit, Jüngerer Finsterauer Kristallgranit, Fein- bis mittel körniger Zweiglimmergranit. Anhand von petrographisch und geochemisch ermittelten Analysendaten wird der folgende Fragenkomplex dargestellt und belegt: 1. Eine Charakterisierung der drei Granitvarietäten hinsichtlich ihres Minera!bestandes und ihrer chemischen Zusammensetzung zur Ermittlung von Kriterien für die Diagnose der Granitgenese. 2. Die genetischen Beziehungen zueinander, insbesondere die der beiden Kristallgranite. 3. Der Verwandtschaftsgrad (Gleichsetzung) des Intrusionszyklus des Jüngeren Finsterauer Kristallgranits mit dem des Eisgarner Granits der österreichischen Gliederung. Neben den qualitativen mikroskopischen Untersuchungen werden von 54 Proben mittels Point-Counter die Modalbestände belegt. Aus 42 Proben (die sich z, T. mit den mikroskopisch untersuchten Proben überlappen) wird röntgenfluoreszenzanalytisch der chemische Bestand folgender Elementkonzentrationen ermittelt: Si, Al, Ti, Fe, Mn, Mg, Ca, Na, K, P, Zn, Rb, Sr, Zr, Ba. Mit Hilfe der kartographisch dargestellten Verteilungspläne der Elementkonzentrationen Si, Fe, K, Ca, Zr und Ba (sowie der Korrelations-Diagramme) wird versucht, genetisch abgrenzbare Konzentrationsbereiche zu charakterisieren, die genetische Hinweise auf einzelne Intrusionsphasen darlegen können. Dies trifft insbesondere auf den Jüngeren Finsterauer Kristallgranit zu.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 552.1 ; Granitische Gesteine {Petrologie} ; Bayern {Geologie} ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 70
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  • 33
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    Eine Hexactinelliden-Faunula aus dem "Chalk" (Maastricht?, Paläozän) Südwest-Ägyptens (2022)
    Reimer, Berlin
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-19
    Description: Aus dem oberpaläozänen "Chalk" Südwest-Ägyptens wird eine Schwammfaunula untersucht. Es wurden 7 Gattungen und 9 Arten nachgewiesen. Die Diagnosen der lychniskiden V e n t r i c u l i t i d a e - Gattungen Schizorhabdus ZITTEL und Rhizopoterion ZITTEL wurden ergänzt bzw. revidiert. Alle weiteren H e x a c ­ t i n o s a werden erstmalig beschrieben. Die ägyptischen H e x a c t i n o s a lehnen sich eng an oberkretazische Gattungen an, zeigen aber zum Teil durch ihre spezialisierte Bauweise eine Organisationshöhe, die sie als eigenständige tertiäre Gattungen ausweisen. Dies gilt insbesondere für die Gattungen Eutactostomium gen. nov. und Diphyllospira gen. nov.. Die Gattung Leptophragma ZITTEL wird erstmalig mit L, pentataxis sp. nov. für das Tertiär nachgewiesen. Die Gattung Plecteurete gen. nov. ist mit zwei Arten vertreten. Sie füllen die im Ter­tiär bestehenden Kenntnislücken, da die E u r e t i n a e s.s. REID mit der Gattung Eurete SEMPER s.l. (siehe REID 1963) bereits aus der Oberkreide und rezent bekannt war. Als einzige der bearbeiteten H e x a c t i n o s a - Gattungen war Aphrocallistes GRAY mit Sicherheit aus dem Tertiär (Miozän) bekannt. A. polycolpos ist der erste Nachweis der Gat­tung Aphrocallistes GRAY im Alt-Tertiär. A. tetraplax steht auf Grund seiner spezialisier­ten Bauweise isoliert unter den A p h r o c a l 1 i s t i d a e .
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 563.4 ; Porifera {Paläozoologie} ; Paläogen {Stratigraphische Paläontologie} ; Ägypten {Paläontologie} ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 38
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  • 34
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    Der Einfluß unterschiedlicher Umweltfaktoren auf Größenwachstum und Schalenbau bei Ostracoden (2022)
    Berlin, Reimer
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-19
    Description: Bei Züchtungsversuchen mit Ostracoden der Brackwasserart» C y p v i n o t u s s a l i n u s , wurde der Einfluß verschiedener Umweltfaktoren auf die Population untersucht. Es zeigte sich, daß eine nicht ausreichende Belichtung einer Verminderung des Längenwachstums um 1/3 und ein Absinken der Populationsdichte um über die Hälfte zur Folge hat. In diesem Fall ist auch der Sauerstoffgehalt des Wassers ein limitierender Faktor, der bei normalen Lichtverhältnissen in ausreichender Menge vorhanden ist. Der Salzgehalt des Wassers führt ebenfalls zu starken Größen und Abundanzschwankungen. Das Minimum für beide Werte lag bei 5%0 , deutlich niedriger als bei den Populationen bei 0%0 und 20%0 . Da auf Grund der verschiedenen Umweltfaktoren Größenunterschiede innerhalb einer Art von 200-300% zu erwarten sind, ist eine Arteneinteilung nach der Größe nicht zu rechtfertigen. Mit steigender Salinität nimmt die Skulptierung der ursprünglich glatten Schale zu. Die Sattelbildung der Schalen wird mit der Muskelkontraktion erklärt. Am stärksten ist die Verformung, wenn die Schalenstabilität verringert wird wie beim verstärkten Einbau von Strontium in die Schale. Die Schalenzusammensetzung ändert sich bei natürlichen Umweltbedingungen fast nicht. Schwankende Magnesiumgehalte sind temperaturabhängig. Mit steigender Strontiumkonzentration im Wasser kommt es zum verstärkten Einbau des Elements in die Schale, so daß sich die ursprüngliche Calcitstruktur in Strontianit und Aragonit umwandelt. Der Einbau von Fremdionen in die Schale wird mit einem kinetisch-thermodynamischen Modell erklärt, was in guter Übereinstimmung mit den experimentellen Ergebnissen steht. Mit diesem Modell kann auch die starke Temperaturabhangigkeit des Magnesiumeinbaus gedeutet werden. Daneben wurde noch der Einfluß der verschiedenen Umweltfaktoren auf das Verhalten der Ostracoden untersucht. Für die Trennung der Ostracoden vom Sand wird ein neues Ausleseverfahren beschrieben.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 565.3 ; Arthropoda {Paläozoologie} ; Paläoökologie ; Ostracoda ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 47
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  • 35
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    Zur Geologie des Großen Walsertales bei Buchboden (2022)
    Berlin, Reimer
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-19
    Description: Aufgrund einer Neukartierung im Maßstab 1 : 10.000 im oberostalpinen Bereich des Großen Walsertales östlich Buchboden und Spezi al Untersuchungen konnte eine Schichfolge, die vom Hauptdolomit bis zur Kreideschiefer-Serie hinaufreicht, ermittelt werden. Hierbei wurden die Kössener-Schichten in Untere- und Obere Kössener-Schichten ausgeschieden. Zusätzlich seien 1 - 2m Radiolarite nahe der Basis der Kreideschiefer-Serie als vermutliches Äquivalent der sogenannten jüngeren Radiolarite (TRAUTH 1948) erwähnt. Zur tektonischen Gliederung lassen sich folgende Aussagen machen: I. Die Buchbodener-Muldenzone, die als relativ breites Jura-Kreide- Gebiet zwischen dem Hauptdolomit des Zitterklapfen-und dem der Walsertal-Schuppe vermittelt, ist keinesfalls eine einfach gebaute Mulde, sondern ein z.T. hochgradig eingeengter, bereichsweise extrem verschuppter Faltenwurf jüngerer Gesteine innerhalb der Allgäu-Schichten*. Mit der zunehmenden Einengung nach Osten hin steigern sich in der Buchbodener-Mulde intensive Verfaltung und Verschuppung, wobei die Mächtigkeit der einzelnen Schichten sprunghaft abnehmen. Die sehr stark tektonische Durchbewegung bedingte einen ständigen Wechsel der geologischen Verhältnisse, die in einigen Abschnitten sogar auf Strecken bis zu 30m voneinander völlig abweichen; eine Korrelation der Schichten ist in der Buchbodener-Mulde sehr schwer, stellenweise auch unmöglich. II. Die im Arbeitsgebiet von der Zitterklapfen-Schuppe abgespaltene Walsertal-Schuppe ist erst östlich Buchboden deutlich abgeschert und tritt über eine kurze Strecke auf, wobei der Normal-Schenkel mit Hauptdolomit einwandfrei auf die Allgäu-Schichten der Oberlut-Mulde überschoben ist. III. Zwischen dem Hauptdolomit der Wandfluh-Schuppe und den Oberen Kössener-Schichten der Walsertal-Schuppe ist im südwestlichen Abschnitt des Gebietes ein Vorkommen der Arosa-Zone eingeschuppt.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 554.3 ; Nördliche Ostalpen {Geologie} ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 16
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    Qualitative und quantitative petrographische Untersuchungen der Kohlen aus den flözführenden Schichten der Antioquia-Formation/Kolumbien (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-13
    Description: Es wurde eine geologische Obersicht der Amaga-Mulde aufgestellt, wobei die kohlenführende Antioquia-Formation besonders behandelt wurde. Die Ergebnisse wurden in einer geologischen und einer tektonischen Karte sowie in Profilen im Maßstab 1 : 50 000 dargestellt. Aus der Amaga-Mulde wurden acht Flözprofiläulen kohlenpetrographisch analysiert. Die makropetrographischen Analysen nach Lithotypen ergaben, daß die Flöze arm an Verwachsungen von Kohle mit Nebengesteinen sind, daß der Lithotyp Fusain fehlt und daß die Kohlen vorwiegend feinstreifig aufgebaut sind. Die qualitativen mikroskopischen Untersuchungen zeigten, daß die Macerale und die Mineralführung wie auch die Vergesellschaftung der Macerale untereinander ähnlich sind. Durch die Kombinationsanalysen wurde die Zusammensetzung der Lithotypen nach Maceralen, Maceralgruppen, Mikrolithotypen und die Zusammensetzung der Mikrolithotypen nach Maceralen ermittelt. Die Maceralgruppenuntersuchungen ergaben, daß die Flöze überwiegend aus Vitriniten aufgebaut und ungewöhnlich arm an Inertiniten sind. Durch die Untersuchungen der einzelnen Lithotypen konnte nachgewiesen werden, daß zwischen den makroskopisch unterschiedenen Lithotypen Durain und Clarain kein eindeutiger Unterschied besteht. Beide Lithotypen sind mehr oder weniger nur aus Vergesellschaftungen von Vitriniten und Exiniten aufgebaut. Insgesamt sind die Schwankungen in der petrographischen Zusammensetzung der Lithotypen aller Flöze so klein, daß, ausgehend von dem makroskopischen Flözschnitt, Rückschlüsse auf die Zusammensetzung der Kohle möglich sind. Es wurden Schlitzproben der Amaga-Mulde untersucht und die Ergebnisse mit den Untersuchungsbefunden der Schlitzproben der Titiribi-Bolombolo-Senke verglichen. Bis auf wenige Ausnahmen sind die Flöze der Titiribi-Bolombolo-Senke höher inkohlt als die der Amaga-Mulde; bei einigen Flözen wird der Inkohlungsgrad von Magerkohlen und Anthraziten erreicht. Diese Kohlen liegen in unmittelbarer Nachbarschaft von vulkanischen Extrusionen. Der hohe Inkohlungsgrad ist auf eine Kontaktmetamorphose zurückzuführen.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 553.24 ; Kolumbien {Geologie} ; Südamerika {Fossile Energieträger} ; Prospektion {Kohlelagerstätten} ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 110
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  • 37
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    Verteilung und Genese von Fluorit im Hauptdolomit Norddeutschlands (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-13
    Description: Die vorliegende Arbeit basiert auf dem Kenntnisstand über die Deutung der Genese von Fluoriten mit Hilfe charakteristischer Gehalte an Seltenerdelementen (SEE). Bisher sind Fluorite aus dem „sedimentären" Bildungsbereich relativ selten untersucht worden. Da Fluoritmineralisationen in Zechsteinkarbonaten bekannt sind, wurden Proben (Bohrungen und Tagesaufschlüsse) aus dem Hauptdolomit Norddeutschlands zur Untersuchung herangezogen. In elf von 14 Bohrungen sowie in drei übertägigen Aufschlüssen wurde Flußspat nachgewiesen. Die Proben wurden analysenfein gemahlen, der Karbonatanteil (93-98 %) mit Salpetersäure herausgelöst und der Probenrückstand röntgenographisch bestimmt. Dieser bestand in der Regel aus Quarz, Fluorit, Anhydrit, Coelestin und Tonmineralen. Für die Analyse des Fluorits auf SEE war es notwendig, eine Abtrennung der Sulfate vorzunehmen, was durch selektives Herauslösen mit Ethylendiamintetraessigsäure (EDTA) gelang. Die Bestimmung der Seltenerdelemente wurde neutronenaktivierungsanalytisch am Hahn-Meitner-Institut für Kernforschung, Berlin, durchgeführt. Der Einfluß von Tonmineralen, die ebenfalls SEE enthalten, auf das Analysenergebnis konnte durch ein Extrapolationsverfahren eliminiert werden. Bedingt durch diese Methode ergab sich aus mehreren Einzelproben einer Bohrung jeweils nur ein Wert für jedes Element der Reihe Lanthan - Lutetium. Auf Einzelinformationen konnte verzichtet werden, da die ermittelten Daten in Form von sogenannten Mischwerten ebenfalls zur genetischen Deutung geeignet sind. Unter Berücksichtigung der Ergebnisse der Dünnschliffuntersuchung kann für die Bohrungen Verden Z1, Hoya Z1, Horstedt Z1 und Hohes Moor Z1 aufgrund der SEE-Gehalte eine marin-sedimentäre Primärgenese des Fluorits abgeleitet werden. Unterschiedlich starke Mobilisationen des Fluorits haben dabei zu Veränderungen der Ausbildungsformen geführt. Die Fluoritgenese in ehemals küstennah abgelagerten Zechsteinsedimenten wird bei Eschwege durch Verdrängung von Karbonaten gedeutet. Aufgrund der Beobachtungen, daß feindisperser Fluorit nur in dolomitischen Gesteinen auftritt und daß Fluorit in Anhydritschichten sowie in Karbonaten mit erhöhten Anhydritgehalten fehlt, wird ein geochemisch - genetisches Modell einer marin-sedimentären Fluoritbildung abgeleitet. Das Modell erklärt die Bildung von Fluorit aus dem Meerwasser basierend auf Vorgängen während der Dolomitisation von kalkigen Sedimenten. Es ermöglicht sowohl die Erklärung der Herkunft der Komponenten Fluor und Calcium als auch die Erklärung der Fluoritbildung selbst. Die petrologische Auswertung des Dünnschliffmaterials unterstreicht die syndolomitische Primärgenese in dolomitischem Trägergestein sowie Mobilisationsvorgänge in dolomitische oder calcitische Horizonte.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 549 ; Halogenide {Mineralogie} ; Ober-Perm ; Flussspat ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 85
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    Die Bedeutung einheimischer Braunkohlevorräte für die Energiebedarfsdeckung ausgewählter Entwicklungsländer (Indien und Thailand) (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-13
    Description: Mit dem Ende des billigen Rohöls setzten weltweit Überlegungen ein, auf welche Weise die Volkswirtschaften derjenigen Staaten, die Mineralöl importieren müssen, mit Energieträgern zu vertretbaren Preisen versorgt werden können. In der vorliegenden Arbeit wird dargestellt, in welchem Maße Entwicklungsländer, die über nennenswerte Vorräte an Braunkohlen verfügen, von einer verstärkten Hinzuziehung dieses Rohstoffs zur Energiebedarfsdeckung profitieren können. Als exemplarische Beispiele dieses Typs von Staaten wurden Indien und Thailand ausgewählt. Indien besitzt Braunkohlenreserven in Hohe von 3,652 Mrd t, als zur Zeit ökonomisch gewinnbar gelten 1,571 Mrd t. Mehr als 90% aller Vorräte befinden sich im südlichen Unionsstaat Tamil Nadu, andere Regionen des Subkontinents, in denen Braunkohle in nennenswertem Umfang festgestellt wurde, sind Gujarat und Rajasthan. Bei einer Steigerung der jährlichen Förderrate von 3,7 Mio t im Jahre 1977 auf 11 Mio t würde die Vorratsdauer bis zur Entkohlung der gewinnbaren Vorräte 142 Jahre betragen. Werden davon 80% als Rohstoffinput in Wärmekraftwerke gegeben, können in diesem Zeitraum jährlich Kraftwerkskapazitäten von 1320 MW betrieben werden. Die thailändischen Braunkohlevorräte betragen über 600 Mio t, davon sind z.Z. 130 Mio t ökonomisch ausbringbar. über 80% der Reserven sind auf N-Thailand konzentriert (Provinzen Lampang und Lampoon), der Rest liegt in der Provinz Krabi (S-Thailand). Würde die momentane Förderungsmenge von ca. 1 Mio t Braunkohle pro Jahr beibehalten, wird der als ökonomisch gewinnbar angesehene Vorrat mehr als 100 Jahre zur Verfügung stehen. Der beträchtliche Ausbau der mit Braunkohle betriebenen Kraftwerkskapazitäten bis 1984 wird diesen Zeitraum auf ca. 30 Jahre verkürzen. Eine Vergrößerung der als wirtschaftlich gewinnbar geltenden Vorräte sowohl in Indien als auch in Thailand erscheint aus verschiedenen Gründen wahrscheinlich...
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 622.1824 ; 553.22 ; Südasien {Fossile Energieträger} ; Kohlenlagerstätten ; Braunkohle ; Braunkohle ; Energieversorgung ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 104
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  • 39
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    Festschrift Max Richter - zum 80. Geburtstag (2022)
    Reimer, Berlin
    In:  Heraugeberexemplar
    Details
    Publication Date: 2022-01-12
    Description: Mit dieser Festschrift soll das wissenschaftliche und akademische Wirken von MAX RICHTER geehrt werden. Anläßlich seines 65. Geburtstages widmeten ihm seine Schüler bereits eine Festschrift, doch setzte der Jubilar seine Lehre und Forschung bis zum heutigen 80. Geburtstag in körperlicher und geistiger Frische fort. Entsprechend der vorrangigen Forschungstätigkeit von MAX RICHTER erhielt die Festschrift als Rahmenthema "Geologie junger Orogene". Über 50 Jahre geologisches Arbeiten in den Alpen, aber auch im gesamten Mittelmeerraum und in Nordamerika erbrachten eine Fülle von Publikationen des Jubilars mit richtungsweisenden Erkenntnissen.
    Description: commemorativepublication
    Description: DFG, SUB Göttingen
    Keywords: 551 ; Orogene als festländische Erdkrustentypen {Tektonik} ; Festschriften {Geologische Wissenschaften} ; Junges Faltengebirge ; Geologie ; FID-GEO-DE-7
    Language: German
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  • 40
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    Geochemische und sedimentpetrographische Untersuchungen zur Gliederung paläozoischer und mesozoischer Sedimente aus der zentralen Sahara (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-12
    Description: Sedimentpetrograpbische und geochemische Untersuchungen an klastischen Sedimenten von zwei paläozoischen und fünf mesozoischen Profilen aus der libyschen Sahara führten zu folgenden Ergebnissen und Schlußfolgerungen: 1. Die Schwermineralzuammensetzung ergibt 80 - 100 % für die stabilen Schwerminerale Zirkon, Turmalin und Rutil sowie geringe Gehalte an Granat, Staurolith u.a.. 2. Die Tonmineralzusammensetzung zeigt eine Kaolinitvormacht mit hohen Illitgehalten in den kambrischen Tonen, die zu den jüngeren Sedimenten hin abnehmen. 3. Die Leichtmineraluntersuchungen erbrachten einen Quarzsandstein mit 95 - 100 % Quarz. 4. Die sedimentpetrographischen Untersuchungen weisen die Ablagerungen als wiederaufgearbeitete Sedimente aus, die im Paläozoikum unter abwechselnd marinen und kontinentalen und im Mesozoikum unter rein kontinentalen Bedingungen abgelagert wurden; ein erhöhter Anteil an Granat und Staurolith im Schwermineral Spektrum an der Wende Devon/Karbon zeigt einen Wechsel im Liefergebiet an, bedingt durch tektonische Bewegungen. Die Ablagerung erfolgte in einem Gebiet mit geringen Reliefunterschieden, in dem überwiegend tropisch­humides Klima herrschte. 5. Cluster- und Faktoren-Analyse der geochemischen Daten ergaben fünf Gruppen sich geochemisch ähnlich verhaltender Elemente: Ca, Sr: An Carbonate gebundene Elemente. Ti, Zr: An Schwerminerale gebundene Elemente. Fe, Mn: Als hydratisierte Oxide ausgefällte Elemente. V, Cr, Ni : Adsorptiv an Eisenhydroxide gebundene Elemente, in geringerem Maße an Tone gebunden. Cu, Zn, Pb: Adsorptiv an Tonminerale gebundene Elemente, in geringerem Maße an Mangan- und Eisenhydroxide. 6. Die Formationen der paläozoischen Profile zeigen eine charakteristische Verteilung der fünf verschiedenen Elementgruppen und können daher an Hand ihrer Elementgehalte geochemisch unterschieden werden. Die mesozoischen Profile können in fünf verschiedene Folgen untergliedert und miteinander parallelisiert werden; jede Folge zeichnet sich durch eine charakteristische Konzentrationsverteilung der fünf verschiedenen Elementgruppen aus. Die Untersuchung zeigt, daß die Schwerminerale Aussagen über die Herkunft der Sedimente liefern und die Spurenelemente als Gliederungskriterium geeignet sind.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 556 ; Sahara im Allgemeinen {Geologie} ; Paläozoikum ; Mesozoikum ; Mesozoikum ; Paläozoikum ; Sediment ; FID-GEO-DE-7
    Language: German
    Type: map
    Format: 96
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  • 41
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    Moore und Torfe in der Bodenkunde: neuere Aspekte (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-08
    Description: Im Hinblick auf die Moore und ihre bodenkundliche Kartierung sind in der letzten (3.) Auflage der Bodenkundlichen Kartieranleitung noch nicht alle bodensystematischen und Ansprache-Probleme zufriedenstellend gelöst. Einer erneuten Diskussion bedürfen (1.) die Berücksichtigung pedogener Profildifferenzierungen in unentwässerten und vor allem in entwässerten (bis degradierten) Mooren sowie (2.) die Frage der Aufgliederung von Mooren bzw. Torfen nach ihrer Azidität (und/oder Trophie), dieses nicht zuletzt hinsichtlich der Praktikabilität ihrer Ansprache bei Kartierungen. An Hand eigener Erfahrungen und neuerer Literatur wird zu diesen Problemkreisen Stellung genommen, und es wird die Richtung angedeutet, in der die Lösungen gesucht werden müssen. Die im Beitrag erörterten Tatsachen und Gesichtspunkte – z.T. schon vor längerer Zeit zusammengestellt – haben Ausgangspunkte für Diskussionen geliefert, die im Hinblick auf eine Neufassung der Moorkapitel der Bodenkundlichen Kartieranleitung sowie der zugrunde liegenden Bodensystematik seit 1988 stattgefunden haben und deren Ergebnisse demnächst veröffentlicht werden sollen.
    Description: In the third edition of the German Soil Survey Manual (Bodenkundliche Kartieranleitung, 1982) some problems concerning peatlands and peatland mapping have not been resolved sufficiently. This applies to peat type identi-fication and to several aspects of general peatland and peat classification. There are two main problems which need new discussions: (1) the variety in profiles, caused by extremely differing pedogenous processes, of virgin and especially of drained mires, (2) the classification of mires or peats in respect to their acidity or trophic conditions considering above all the possibilities to identify the types under field conditions in soil mappings. These problems are reviewed on the basis of recent literature and in the light of the author’s own experience, and directions of possible solutions are suggested. The quoted facts, most of which were presented some time ago, yielded the starting point for discussions in the DGMT (German Peat Science Society) on a revised text of the mire and peat sections of the Soil Survey Manual and their basic soil classification, the results of which will be published in the near future.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; e-docs::Geologische Wissenschaften ; Moor ; Ökologie ; Torf ; peat ; peatland ; bog ; vegetation ; FID-GEO-DE-7
    Language: German
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  • 42
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    Zur Gliederung und Ansprache mitteleuropäischer Torfe (Vorschläge für die 4. Auflage der Bodenkundlichen Kartieranleitung) (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-08
    Description: Für den Abschnitt "Torfe" der Bodenkundlichen Kartieranleitung, deren 4. Auflage zur Zeit vorbereitet wird, wurde ein neuer Textvorschlag erarbeitet, der hiermit vorgelegt wird. Behandelt werden darin 1) die unterschiedlichen Klassifikationsmöglichkeiten der Torfe auf "botanischer" Grundlage (in den Torfen vertretene Pflanzenreste) sowie im Hinblick auf (primäre) bodenkundlich-chemische Eigenschaften (Basen- und pH-Verhältnisse), 2) die wichtigsten im Gelände ansprechbaren Pflanzenreste und ihre Merkmale, 3) die Zuordnung von verbreiteten botanisch charakterisierten Torfarten (oder "Torfarteneinheiten") zu den bodenkundlichen "Torfartengruppen" Hoch-, Übergangs- und Niedermoortorf an Hand einer Tabelle. Das entscheidende Kriterium für die Zuordnung zum Hochmoortorf ist das ausschließliche Vorkommen der Reste von Hochmoorpflanzen (diese werden im einzelnen aufgeführt). Übergangsmoortorfe sind durch die Reste von Pflanzenarten ausgezeichnet, die an basen- und nährstoffärmere Standorte außerhalb von Hochmooren gebunden sind (neben ihnen können aber auch Hochmoorpflanzen-Reste vertreten sein). Niedermoortorfe sind charakterisiert durch Reste basen- und nährstoffanspruchsvoller Arten (neben denen auch Reste anspruchsloserer Arten vertreten sein können).
    Description: Proposals are given for a new text of the section "Peat" of the German Soil Mapping Instruction, the 4th edition of which is now under preparation. The topics dealt with are as follows: 1. The different possibilities of classification of peat: on "botanical" basis (their contents of plant remains) and with respect to (primary) chemico-pedological characteristics (base and pH conditions). 2. The characteristics of the most common plant remains identifiable in the field. 3. The assignment of widespread botanical peat types to the three pedological peat groups: raised-bog peat, transitional-mire peat, and fen peat (shown by a table). The criterion decisive on the assignment of a given peat to raised-bog peat is the exclusive occurrence of remains of raised-bog plants (these are quoted in detail). Transitional-mire peats are distinguished by remains of plant species, which are restricted to sites poor in bases and nutrients (beyond the raised bogs, however), besides of them also raised-bog plant remains may be present. Fen peats are characterized by remains of base and nutrient demanding species (besides of them also remains of plants of poorer sites, but not of raised bogs may be present).
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; e-docs::Geologische Wissenschaften::Stratigraphie ; Moor ; Torf ; vegetation ; peat ; peatland ; bog ; FID-GEO-DE-7
    Language: German
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  • 43
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    Einige allgemeine Ergebnisse von Torf-Großrestuntersuchungen (2022)
    In:  SUB Göttingen | ZA 34278
    Details
    Publication Date: 2022-01-08
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; Moor ; Ökologie ; Torf ; vegetation ; peat ; peatland ; bog ; FID-GEO-DE-7
    Language: German
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  • 44
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    Moore und Moor-Naturschutzgebiete in Deutschland ‒ eine Bestandsaufnahme (2022)
    In:  SUB Göttingen | ZA 34278
    Details
    Publication Date: 2022-01-08
    Description: Im vorliegenden Artikel wird über deutsche Naturschutzgebiete berichtet, die wenigstens teilweise Moorflächen enthalten; "Moor" wird hier im geologisch-bodenkundlichen Sinn als Gebiet mit einer Torfdecke von mindestens 30 cm verstanden. Die Zahlen solcher Moor-Naturschutzgebiete der einzelnen Bundesländer sind in Tabelle 2 zusammengestellt. Dabei wurden Naturschutzgebiete, die Hochmoorflächen ‒ gleich, welcher Größe ‒ enthalten, und Gebiete mit ausschließlich Niedermoorvorkommen (vielfach neben Mineralbodenflächen) getrennt erfaßt. Außer Zahlen für die Gegenwart (1992 bis 1996‚ je nach dem Jahr der in den einzelnen Ländern zugrundeliegenden Erhebungen) wurden die entsprechenden Daten auch für 1970 und 1945 wiedergegeben, und es wurde versucht, einige allgemeine Züge hinsichtlich der regionalen Verteilung sowie der Zeitpunkte der Ausweisungen herauszuarbeiten. Ergänzend werden einige neue Zahlen über die Gesamt-Moorflächen der einzelnen Bundesländer genannt (Kapitel 2) sowie einige Tatsachen über die Anfänge und die weitere Entwicklung des Moor-Naturschutzes in Deutschland seit der Jahrhundertwende wiedergegeben (Kapitel 3.2). Ein Anhang (Kapitel 5) enthält Details über die Moor-Naturschutzgebiete, teilweise auch über die Gesamt-Moorflächen der einzelnen Bundesländer.
    Description: The paper deals with German nature-reserves containing peatland areas in at least some proportion. Peatland is meant here in the sense of areas with a peat cover of more than 30 cm thickness. The numbers and total areas of these "peatland nature-reserves” of the different German Federal States are listed in table 2. Here a distinction is made between nature-reserves containing larger or smaller proportions of ombrotrophic mires (bogs) and others which only comprise minerotrophic mires (fens), both of them in many cases amongst the mire areas with mineral soils too. The numbers and areas are given not only for present days (i.e. the years between 1992 and 1996, varying in the single States) but also for 1970 and 1945. It is tried to work out some general features with regard to the regional distribution of the peatland nature-reserves as well as to the times of their establishment. In addition, some new data on the total peatland areas of the single German Federal States are quoted (chapter 2) and some facts are compiled on the beginnings and development of mire conservation activities in Germany since the turn of our century (chapter 3.2). In an appendix (chapter 5) details on peatland nature-reserves, in part also on peatland areas of the different German Federal States are given.
    Description: report
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; e-docs::Geologische Wissenschaften::Regionale Geologie::Mitteleuropa nach Politischen Ländern {Geologie} ; Moor ; Torf ; Naturschutz ; peat ; peatland ; bog ; fen ; FID-GEO-DE-7
    Language: German
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  • 45
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    Probleme der Kartierung und Systematik der Moorböden ‒ Eine Diskussion in Lingen und was bislang daraus geworden ist (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-08
    Description: Es wird über eine 1993 durchgeführte Diskussionsveranstaltung zum Thema einer bundeseinheitlichen Ansprache und Kartierung von Mooren berichtet. Ein wichtiges Ziel der Diskussionen (sowie einiger im Anschluß an die Veranstaltung verfaßter schriftlicher Exposes) war die Suche nach Möglichkeiten einer Einpassung wesentlicher Teile des Moorkartierungs-Standards TGL 24300/04 der früheren DDR in die zur Zeit vorbereitete 4. Auflage der Bodenkundlichen Kartieranleitung der Geologischen Landesämter. Eine inhaltliche Übernahme war für eine Reihe von Punkten recht gut möglich: andere jedoch erwiesen sich als weitgehend inkompatibel mit den derzeitigen Konzepten für die Neuauflage der Kartieranleitung, die nunmehr sehr bald herausgebracht werden soll. Hierbei handelt es sich insbesondere um die bodensystematische Einstufung der durch entwässerungs- und nutzungsbedingte Einflüsse pedologisch besonders stark veränderten Niedermoorböden sowie um die Gliederung und Terminologie subfossiler mineralischer bis ± organischer limnischer Sedimente. Über die hiermit zusammenhängenden Probleme und einige in Frage kommende Lösungsmöglichkeiten wird ausführlich berichtet. Es ist zu hoffen, daß durch Fortsetzung der Diskussion bald eine einhellige Auffassung der deutschen Moor- und Torfspezialisten erarbeitet werden kann.
    Description: Report is given on a discussion meeting held in 1993 on German standards for peatland mapping and matters connected with them. One of the significant aims of the discussion (and of papers put forward later on, too) was to look for possibilities to fit several essential parts of the peatland standard TGL 24300/04 of the former German Democratic Republic into the next (4th) edition of the German Soil Mapping Instruction being in preparation now. This proved to be fairly well possible for some of the topics of the TGL-standard; others, however, tourned out to be largely incompatible with the present concepts of the new edition of the Soil Mapping Instruction, the completion of which is planned to be finished in near future. The main points in question so far were the pedological classification of peat soils heavily degraded by drainage and agricultural utilization, and the classification and terminology of mineral to i organic subfossil lacustrine sediments. Problems related to that and possibilities of solution are reported. The author is hoping that the German peat experts, in continuating the discussion of these problems, achieve unanimous solutions in near future.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; e-docs::Geologische Wissenschaften::Angewandte Geowissenschaften::Geologische Kartographie::Geologisches Kartieren ; Moor ; Torf ; peat ; peatland ; bog ; FID-GEO-DE-7
    Language: German
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  • 46
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    Über pflanzliche Makrofossilien mitteleuropäischer Torfe (2022)
    In:  SUB Göttingen | ZA 34278
    Details
    Publication Date: 2022-01-08
    Description: Von den in Torfen vorkommenden pflanzlichen Makrofossilien werden im vorliegenden ersten Teil der Arbeit die Gewebereste krautiger Pflanzen nach ihren makroskopischen und mikroskopischen Merkmalen an Hand von zahlreichen Fotos beschrieben; die Einzelbeschreibungen werden durch Gegenüberstellungen der diagnostisch wichtigsten Merkmale ‒ in Form von Bestimmungsschlüsseln ‒ ergänzt. Der später folgende zweite Teil der Arbeit wird weitere Pflanzenreste (insbesondere Früchte und Samen sowie Moose) behandeln, Angaben über die Untersuchungsmethoden machen und das Literaturverzeichnis nachtragen.
    Description: Title: On plant macrofossils of central European peats. I. Tissue remains of herbaceous plants and their characteristics. In this paper descriptions of the macroscopic and microscopic characters of herbaceous plant remains are given together with numerous photos. The individual descriptions are supplemented by presentations of the most important distinctive characters in identification keys. A following paper will describe some further remains (mosses, fruits and seeds etc.) and methods of investigation, it will contain, too, the whole bibliography.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; Moor ; Ökologie ; Torf ; peat ; peatland ; vegetation ; bog ; FID-GEO-DE-7
    Language: German
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  • 47
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    Über pflanzliche Makrofossilien mitteleuropäischer Torfe (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-07
    Description: Von den in Torfen vorkommenden pflanzlichen Makrofossilien werden im vorliegenden ersten Teil der Arbeit die Gewebereste krautiger Pflanzen nach ihren makroskopischen und mikroskopischen Merkmalen an Hand von zahlreichen Fotos beschrieben; die Einzelbeschreibungen werden durch Gegenüberstellungen der diagnostisch wichtigsten Merkmale ‒ in Form von Bestimmungsschlüsseln ‒ ergänzt. Der später folgende zweite Teil der Arbeit wird weitere Pflanzenreste (insbesondere Früchte und Samen sowie Moose) behandeln, Angaben über die Untersuchungsmethoden machen und das Literaturverzeichnis nachtragen.
    Description: Title: On plant macrofossils of central European peats. I. Tissue remains of herbaceous plants and their characteristics. In this paper descriptions of the macroscopic and microscopic characters of herbaceous plant remains are given together with numerous photos. The individual descriptions are supplemented by presentations of the most important distinctive characters in identification keys. A following paper will describe some further remains (mosses, fruits and seeds etc.) and methods of investigation, it will contain, too, the whole bibliography.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; Moor ; Umweltwissenschaften ; Ökologie ; Torf ; peat ; peatland ; bog ; fen ; FID-GEO-DE-7
    Language: German
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  • 48
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    Bericht über die gemeinsame Fachtagung der Sektionen I und V, DGMT, und der Sächsischen Akademie für Natur und Umwelt vom 30. September bis zum 4. Oktober 1998 in Niederlauterstein/ Erzgebirge über „Moore in ihrer Beziehung zu Gehölzbeständen“ (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-11
    Description: Eine Veranstaltung der Sektionen I (Geowissenschaften) und V (Naturschutz und Raumordnung) fand – drei Jahre nach der Tagung in Greifswald – wiederum im östlichen Teil Deutschlands statt, dieses Mal im mittleren Erzgebirge, und zwar in Niederlauterstein, einem kleinen, nordöstlich der Stadt Marienberg gelegenen Ort. Sie wurde gemeinsam mit der Sächsischen Akademie für Natur und Umwelt durchgeführt; die Sächsische Landesstiftung Natur und Umwelt, zu der die Akademie gehört, hatte dankenswerterweise beträchtliche Mittel dafür zur Verfügung gestellt. Sachsen gehört mit knapp 100 km2 Moor-boden)-fläche zu den recht moorarmen Bundesländern; im Erzgebirge gibt es jedoch, vor allem in den Kammlagen, sehr zahlreiche Moore. Im deutschen Teil des Gebirges nehmen bereits die als Naturschutzgebiete ausgewiesenen Hochmoore gegen 10 km2 ein, die Hochmoor-Gesamtfläche dürfte hier jedoch noch um einiges größer sein; die Moorfläche im tschechischen Teil des Erzgebirges beläuft sich auf etwa 40 km2.
    Description: excursionguide
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; Moor ; Torf ; peat ; peatland ; bog ; fen ; FID-GEO-DE-7
    Language: German
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    Bericht über die gemeinsame Arbeitstagung von Sektion I (Geowissenschaften) und Sektion V (Naturschutz und Raumordnung) der DGMT vom 30. August bis zum 2. September 1995 in Mecklenburg-Vorpommem (Greifswald) (2022)
    In:  Herausgeberexemplar
    Details
    Publication Date: 2022-01-11
    Description: Mecklenburg-Vorpommern, mit ca.350000 ha Mooren (= 17 % der Landesfläche) nach Brandenburg (14 % Moore) moorreichstes unter den neuen Bundesländern, fordert mit der Vielfalt seiner Niedermoore immer wieder zum Vergleich mit anderen mitteleuropäischen Moorlandschaften heraus. Bei dieser Vielfalt geht es nicht nur um die ursprünglichen, durch die verschiedensten landschaftsökologischen Gegebenheiten bedingten Moortypen, sondern auch um die schwerwiegenden Veränderungen, die in den Mooren während der letzten Jahrzehnte infolge tiefgreifender "Meliorationen" und landwirtschaftlicher Intensivnutzung vor sich gegangen sind und die zu einer Vielzahl von negativen Ökologischen (und auch Ökonomischen) Auswirkungen geführt haben.
    Description: excursionguide
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; Moor ; Torf ; peat ; peatland ; bog ; fen ; FID-GEO-DE-7
    Language: German
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    Göttinger Konzept zur Entwicklung einer Methode zur Anwendung des Signifikanzkriteriums Schadenspotenzial bei der Überprüfung der Bewertung des Hochwasserrisikos gemäß EG-HWRM-RL (2022)
    FID GEO, Göttingen
    Details
    Publication Date: 2022-11-08
    Description: Die europäische Hochwasserrisikomanagementrichtlinie (EG-HWRM-RL) verpflichtet die Mitgliedsstaaten zu Beginn jedes Berichtszyklus, die Bewertung des Hochwasserrisikos einschließlich der Bestimmung der Risikogebiete zu überprüfen und gegebenenfalls zu aktualisieren. Der Ausschuss "Hochwasserschutz und Hydrologie" der Bund/Länder-Arbeitsgemeinschaft Wasser empfiehlt im Rahmen dessen, zur Harmonisierung der Ländervorgehen das Signifikanzkriterium "Schadenspotenzial" anzuwenden. Dies soll ab dem dritten Zyklus, beginnend im Jahr 2022, erfolgen. Dieses Dokument enthält ein Konzept zur Entwicklung einer bundeseinheitlichen Methode zur Anwendung des Signifikanzkriteriums "Schadenspotenzial" einschließlich der Schadenspotenzialermittlung bei der Überprüfung der Bewertung des Hochwasserrisikos gemäß EG-HWRM-RL. Dieses sogenannte "Göttinger Konzept" wurde durch den Einsatz verschiedener qualitativer Methoden erstellt. Es listet strukturiert, zusammenfassend und transparent Prüf- und Arbeitsschritte mit Arbeitsanweisungen und Bearbeitungshinweisen auf, die sich in erster Linie an die zuständigen Behörden richten. Dabei bezieht es Hinweise und Anforderungen einschlägiger Dokumente ein und verfolgt einen ganzheitlichen Ansatz. Über die Einbindung einer Schadenspotenzialermittlung wird eine ökonomische Bewertung in das bestehende nationale Vorgehen zur Bewertung potenziell nachteiliger Folgen auf das Schutzgut "wirtschaftliche Tätigkeiten und erhebliche Sachwerte" integriert. Monetäre Werthöhen und ihre räumliche Verteilung, die Exposition und die Schadanfälligkeit sowie Vulnerabilität werden dabei einbezogen. Das Ergebnis der Schadenspotenzialermittlung sind monetäre Schäden, die als Teilinformationen zur Abschätzung von Hochwasserrisiken und der Ausweisung von Risikogebieten genutzt werden. Der Artikel, in dem das Konzept beschreiben wird, ist in der Zeitschrift „Hydrologie und Wasserbewirtschaftung“ veröffentlicht.
    Description: Abstract: 〈p〉 〈p〉 The European Floods Directive obliges the member states at the beginning of each reporting cycle to review and, if necessary, update the preliminary flood risk assessment including the identification of areas of potential significant flood risk. Within this framework, the Committee "Flood Protection and Hydrology" of the German Working Group on water issues recommends the significance criterion ”damage potential“ in order to harmonize the approaches of the federal states. This is to be done from the third cycle onwards, starting in 2022. This document contains a concept for the development of a nationwide uniform method for the application of the significance criterion ”damage potential“ including the damage potential assessment in the review of the preliminary flood risk assessment according to the Floods Directive. This so called ”Göttingen concept“ was developed by using different qualitative methods. It lists test and work steps with work instructions and processing notes in a structured, summarizing and transparent way. Thereby, the concept is primarily addressed to the responsible authorities. It incorporates references and requirements of relevant documents and follows a holistic approach. By incorporating a damage potential assessment, an economic assessment is integrated into the existing national procedure for assessing potential adverse impacts on “economic activities and significant material assets”. Monetary values and their spatial distribution, exposure and damage susceptibility and vulnerability are included. The result of the damage potential assessment is monetary damages, which are used as partial information for the assessment of flood risks and the identification of areas of potential significant flood risk. The article describing the concept is published in the journal "Hydrologie und Wasserbewirtschaftung".
    Description: https://doi.org/10.5675/HyWa_2023.1_1
    Description: research
    Keywords: ddc:551.48 ; Hochwasserrichtlinie ; Hochwasserrisiko ; Risikobewertung ; Signifikanzkriterium ; Schadenspotenzial ; Hochwasserschäden ; EG-Hochwasserrisikomanagementrichtlinie ; HWRM-RL ; Risikobewertung
    Language: German
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    Continental Break‐Up Under a Convergent Setting: Insights From P Wave Radial Anisotropy Tomography of the Woodlark Rift in Papua New Guinea (2022)
    Details
    Publication Date: 2022-12-05
    Description: To explore the dynamic mechanism of continental rifting within a convergent setting, we determine the first P wave radial anisotropic tomography beneath the Woodlark rift in southeastern Papua New Guinea, which develops within the obliquely colliding zone between the Australian and southwest Pacific plates. The rift zone is depicted as localized low‐velocity anomalies with positive radial anisotropy, which rules out a dominant role of active mantle upwelling in promoting the rift development and favors passive rifting with decompression melting as main processes. Downwelling slab relics in the upper mantle bounding the rift zone are revealed based on observed high‐velocity anomalies and negative radial anisotropy, which may contribute to the ultra‐high pressure rock exhumations and rift initiation. Our observations thus indicate that the Woodlark rift follows a passive model and is mainly driven by slab pull from the northward subduction of the Solomon plate.
    Description: Plain Language Summary: The Woodlark rift in Papua New Guinea develops within the shear zone between the Australian and southwest Pacific plates and is one of the youngest and most rapidly extending continental rifts in the world. In this work, we analyze teleseismic P wave arrivals to study both 3‐D velocity and radial anisotropy structures of the upper mantle, offering new evidence to understand rift initiation under a generally convergent setting. Slab remnants in the upper mantle bordering the rift zone are detected and sinking into the deeper mantle. Downwelling of these slab segments may induce small scale return flows in the mantle and contribute to exhumation of the ultra‐high pressure rocks and rift development. Significant low‐velocity anomalies are revealed beneath the rift zone and have consistently positive radial anisotropy, which indicates a dominant strain in the horizontal plane and supports a passive rifting model, where mantle material is brought to shallower depths simply as a result of the extension of the lithosphere and melt is produced due to the lowered melting point at reduced pressure (decompression melting). Tensional stresses transferred from slab pull of the northward Solomon subduction are probably driving the rifting.
    Description: Key Points: P wave radial anisotropic structure beneath the young and highly extended Woodlark rift is constrained from teleseismic tomography. Downwelling of slab relics bordering the rift zone may contribute to ultra‐high pressure rock exhumation and rift development. Slab‐pull drives rift initiation and induces decompression melting in the upper mantle under the rift zone by horizontal stress transfer.
    Description: National Natural Science Foundation of China (NSFC) http://dx.doi.org/10.13039/501100001809
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Description: MEXT | Japan Society for the Promotion of Science (JSPS) http://dx.doi.org/10.13039/501100001691
    Description: Alexander von Humboldt‐Stiftung (Humboldt‐Stiftung) http://dx.doi.org/10.13039/100005156
    Description: https://doi.org/10.7914/SN/XD_1999
    Description: https://doi.org/10.7914/SN/ZN_2010
    Keywords: ddc:551 ; Woodlark rift ; radial anisotropy ; decompression melting ; slab‐pull ; slab downwelling ; ultra‐high pressure rock
    Language: English
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    Direct Evidence of a Slow‐Slip Transient Modulating the Spatiotemporal and Frequency‐Magnitude Earthquake Distribution: Insights From the Armutlu Peninsula, Northwestern Turkey (2022)
    Bocchini, G. M. ; Martínez‐Garzón, P. ; Verdecchia, A. ; [et al.]
    Details
    Publication Date: 2022-12-05
    Description: Earthquakes and slow‐slip events interact, however, detailed studies investigating their interplay are still limited. We generate the highest resolution microseismicity catalog to date for the northern Armutlu Peninsula in a ∼1‐year period to perform a detailed seismicity distribution analysis and correlate the results with a local, geodetically observed slow‐slip transient within the same period. Seismicity shows a transition of cluster‐type behavior from swarm‐like to burst‐like, accompanied by an increasing relative proportion of clustered (non‐Poissonian) relative to background (Poissonian) seismicity and gradually decreasing b‐value as the geodetically observed slow‐slip transient ends. The observed slow‐slip transient decay correlates with gradually increasing effective‐stress‐drop values. The observed correlation between the b‐value and geodetic transient highlights the influence of aseismic deformation on seismic deformation and the impact of slow‐slip transients on local seismic hazard.
    Description: Plain Language Summary: Seismic and aseismic slip on faults can change the stress state in the crust and affect the recurrence time of earthquakes. Observations of how earthquakes and aseismic fault slip influence each other are limited because of the dearth of synchronous high‐resolution seismological and geodetic data. Here we use high‐resolution earthquake data in the northern Armutlu Peninsula along the Marmara seismic gap of the North Anatolian Fault (Turkey) to correlate the earthquake distribution with a local slow‐slip transient that occurred in the same period. We find that the slow‐slip transient modulates the spatiotemporal and frequency‐magnitude evolution of earthquakes, which highlights the influence of slow fault creep on fast fault slip. Our study demonstrates the importance of considering slow‐slip transients for seismic hazard assessment.
    Description: Key Points: Seismicity analysis suggests that both external and internal forcing drive deformation in the Armutlu Peninsula. Temporal correlation between a slow‐slip transient and seismic b‐value highlights interactions between aseismic and seismic deformation. Slow‐slip transients modulate the frequency‐magnitude and spatiotemporal earthquake distribution.
    Description: VW momentum grant
    Description: Helmotz Association Young Investigator Group http://dx.doi.org/10.13039/501100009318
    Description: Helmholtz‐Zentrum Potsdam—Deutsches GeoForschungs Zentrum GFZ, GIPP http://dx.doi.org/10.13039/501100010956
    Keywords: ddc:551.22 ; microseismicity ; enhanced catalog ; near‐fault monitoring ; seismic‐aseismic deformation ; slow‐slip transient
    Language: English
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    On the trail of iron uptake in ancestral Cyanobacteria on early Earth (2022)
    Enzingmüller‐Bleyl, Tristan C. ; Boden, Joanne S. ; Herrmann, Achim J. ; [et al.]
    Details
    Publication Date: 2022-12-05
    Description: Cyanobacteria oxygenated Earth's atmosphere ~2.4 billion years ago, during the Great Oxygenation Event (GOE), through oxygenic photosynthesis. Their high iron requirement was presumably met by high levels of Fe(II) in the anoxic Archean environment. We found that many deeply branching Cyanobacteria, including two Gloeobacter and four Pseudanabaena spp., cannot synthesize the Fe(II) specific transporter, FeoB. Phylogenetic and relaxed molecular clock analyses find evidence that FeoB and the Fe(III) transporters, cFTR1 and FutB, were present in Proterozoic, but not earlier Archaean lineages of Cyanobacteria. Furthermore Pseudanabaena sp. PCC7367, an early diverging marine, benthic strain grown under simulated Archean conditions, constitutively expressed cftr1, even after the addition of Fe(II). Our genetic profiling suggests that, prior to the GOE, ancestral Cyanobacteria may have utilized alternative metal iron transporters such as ZIP, NRAMP, or FicI, and possibly also scavenged exogenous siderophore bound Fe(III), as they only acquired the necessary Fe(II) and Fe(III) transporters during the Proterozoic. Given that Cyanobacteria arose 3.3–3.6 billion years ago, it is possible that limitations in iron uptake may have contributed to the delay in their expansion during the Archean, and hence the oxygenation of the early Earth.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Royal Society of Biology http://dx.doi.org/10.13039/100012361
    Description: University of Bristol http://dx.doi.org/10.13039/501100000883
    Description: https://osf.io/7x598/?view_only=715cd38c378446ba8c3f6c924f9be9f5
    Keywords: ddc:561.91 ; Archean ; Bayesian ; Cyanobacteria ; iron uptake ; molecular clock ; Pseudanabaena sp. PCC7367
    Language: English
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    The Synergy of Data From Profiling Floats, Machine Learning and Numerical Modeling: Case of the Black Sea Euphotic Zone (2022)
    Details
    Publication Date: 2022-12-05
    Description: Data from profiling floats in the Black Sea revealed complex temporal and spatial relationships between physical variables and oxygen, chlorophyll and the backscattering coefficient at 700 nm, as well as some limits in understanding the details of biogeochemistry dynamics. To account for different interdependences between physical and biogeochemical properties, a feedforward backpropagation neural network (NN) was used. This NN learns from data recorded by profiling floats and predicts biogeochemical states using physical measurements only. The performance was very high, particularly for oxygen, but it decreased when the NN was applied to older data because the interrelationships between the physical and biogeochemical properties have changed recently. The biogeochemical states reconstructed by the NN using physical data produced by a coupled physical–biogeochemical operational model were better than the biogeochemical outputs of the same coupled model. Therefore, the use of data from profiling floats, physical properties from numerical models and NNs appears to be a powerful approach for reconstructing the 4D dynamics of the euphotic zone. Basin‐wide patterns and temporal variabilities in oxygen, backscattering coefficient and chlorophyll were also analyzed. Of particular interest is the reconstruction of short‐lived biogeochemical features, particularly in coastal anticyclone areas, which are difficult to observe with available floats at the basin scale.
    Description: Plain Language Summary: This study addresses the biogeochemical dynamics of the euphotic layer in the Black Sea. Observations are provided from profiling floats, and the observed biogeochemical parameters include oxygen, the backscattering coefficient at 700 nm and chlorophyll‐a. Data analysis showed complex temporal and spatial relationships between physical and biogeochemical variables and some limits in understanding the details of biogeochemical dynamics. A feedforward backpropagation neural network was developed, which can be considered an input–output mapping in which the neurons combine the input data in such a way that the output can be considered a nonlinear combination of input data. When applied to older data, the reconstruction performance decreases, suggesting a change in the dependency of biogeochemical characteristics on physical drivers caused by known climate change. A comparison with simulations from a coupled operational biogeochemical model shows that the neural network outperforms the numerical model. The newly proposed method, combining data from profiling floats, physical properties from numerical models and a backpropagation neural network, allows us to reconstruct the 4D dynamics of the euphotic layer over the period 2013–2020.
    Description: Key Points: Machine learning helps identify fundamental biogeochemical mechanisms in the Black Sea. A feedforward backpropagation neural network performs better than a coupled physical‐biogeochemical model. Data from profiling floats, physical data from numerical models and machine learning enabled the analysis of 4D biogeochemical dynamics.
    Description: MASRI
    Description: National Roadmap for Scientific Infrastructure
    Description: European Horizon 2020 project DOORS
    Description: https://resources.marine.copernicus.eu/product-detail/BLKSEA_MULTIYEAR_PHY_007_004/INFORMATION
    Description: https://resources.marine.copernicus.eu/product-detail/BLKSEA_REANALYSIS_BIO_007_005/INFORMATION
    Description: http://www.coriolis.eu.org/Data-Products/Data-selection
    Description: https://zenodo.org/record/6860705
    Keywords: ddc:551 ; biogeochemistry ; neural networks ; profiling floats ; euphotic zone
    Language: English
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    Atmospheric circulation patterns that trigger heavy rainfall in West Africa (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2022-12-05
    Description: Classification of atmospheric circulation patterns (CP) is a common tool for downscaling rainfall, but it is rarely used for West Africa. In this study, a two‐step classification procedure is proposed for this region, which is applied from 1989 to 2010 for the Sudan‐Sahel zone (Central Burkina Faso) with a focus on heavy rainfall. The approach is based on a classification of large‐scale atmospheric CPs (e.g., Saharan Heat Low) of the West African Monsoon using a fuzzy rule‐based method to describe the seasonal rainfall variability. The wettest CPs are further classified using meso‐scale monsoon patterns to better describe the daily rainfall variability during the monsoon period. A comprehensive predictor screening for the seasonal classification indicates that the best performing predictor variables (e.g., surface pressure, meridional moisture fluxes) are closely related to the main processes of the West African Monsoon. In the second classification step, the stream function at 700 hPa for identifying troughs and ridges of tropical waves shows the highest performance, providing an added value to the overall performance of the classification. Thus, the new approach can better distinguish between dry and wet CPs during the rainy season. Moreover, CPs are identified that are of high relevance for daily heavy rainfall in the study area. The two wettest CPs caused roughly half of the extremes on about 6.5% of days. Both wettest patterns are characterized by an intensified Saharan Heat Low and a cyclonic rotation near the study area, indicating a tropical wave trough. Since the classification can be used to condition other statistical approaches used in climate sciences and other disciplines, the presented classification approach opens many different applications for the West African Monsoon region.
    Description: A two‐step classification of daily atmospheric circulation patterns is used to describe seasonal and daily rainfall variability in West Africa. The approach clearly distinguishes between dry and wet patterns if sea level pressure and stream function at 700 hPa are used. The two wettest patterns trigger about half of heavy rainfall events in Central Burkina Faso. They are characterized by an intensified Saharan Heat Low and a cyclonic rotation indicating a tropical wave trough near the study area.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:551.5 ; circulation pattern ; classification ; downscaling ; heavy rainfall ; West Africa
    Language: English
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    Bergordnung Markgraf Christoph I. von Baden für den Königswart (2022)
    Details
    Publication Date: 2022-11-13
    Description: Diese als Bergfreiheit bezeichnete Bergordnung für die am Königswart in der Grafschaft Eberstein gelegenen Bergwerke wurde am 27. Februar 1488 von Markgraf Christoph I. von Baden erlassen. In der Einleitung berief man sich auf die Bergordnungen für die Bergwerke an der Etsch, in Schwatz sowie Sterzing und gewährte den Bergleuten dieselben Rechte.
    Description: source
    Keywords: ddc:622 ; Markgraf Christoph I. von Baden ; Grafschaft Eberstein ; Grafschaft Sponheim ; Berg/Burg Königswart ; Baden ; Schwaz ; Sterzing ; Etsch (Fluss) ; Silberbergbau ; Markgrafschaft Baden ; Bergordnung
    Language: German
    Type: doc-type:book
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    Limited Earthquake Interaction During a Geothermal Hydraulic Stimulation in Helsinki, Finland (2022)
    Kwiatek, Grzegorz ; Martínez‐Garzón, Patricia ; Davidsen, Jörn ; [et al.]
    Details
    Publication Date: 2022-11-26
    Description: We investigate induced seismicity associated with a hydraulic stimulation campaign performed in 2020 in the 5.8 km deep geothermal OTN‐2 well near Helsinki, Finland as part of the St1 Deep Heat project. A total of 2,875 m3 of fresh water was injected during 16 days at well‐head pressures 〈70 MPa and with flow rates between 400 and 1,000 L/min. The seismicity was monitored using a high‐resolution seismic network composed of 10 borehole geophones surrounding the project site and a borehole array of 10 geophones located in adjacent OTN‐3 well. A total of 6,121 induced earthquakes with local magnitudes MLHel〉−1.9 ${M}_{\mathrm{L}}^{\mathrm{H}\mathrm{e}\mathrm{l}} 〉 -1.9$ were recorded during and after the stimulation campaign. The analyzed statistical parameters include magnitude‐frequency b‐value, interevent time and interevent time ratio, as well as magnitude correlations. We find that the b‐value remained stationary for the entire injection period suggesting limited stress build‐up or limited fracture network coalescence in the reservoir. The seismicity during the stimulation neither shows signatures of magnitude correlations, nor temporal clustering or anticlustering beyond those arising from varying injection rates. The interevent time statistics are characterized by a Poissonian time‐varying distribution. The calculated parameters indicate no earthquake interaction. Focal mechanisms suggest that the injection activated a spatially distributed network of similarly oriented fractures. The seismicity displays stable behavior with no signatures pointing toward a runaway event. The cumulative seismic moment is proportional to the cumulative hydraulic energy and the maximum magnitude is controlled by injection rate. The performed study provides a base for implementation of time‐dependent probabilistic seismic hazard assessment for the project site.
    Description: Plain Language Summary: We investigate anthropogenic seismicity associated with fluid injection into the 5.8 km deep geothermal OTN‐2 well near Helsinki, Finland, as a part of St1 Deep Heat Project. A total of 2,875 m3 of fresh water was injected during 16 days at well‐head pressures 〈70 MPa and with flow rates between 400 and 1,000 L/min. The seismicity was monitored using a seismic network composed of 20 borehole geophones located in Helsinki area and in the OTN‐3 well located close by the injection site. A total of 6,121 earthquakes indicating fractures of 1–30 m size were recorded during and after stimulation campaign. Using a handful of statistical properties derived from earthquake catalog we found no indication for earthquakes being triggered by other earthquakes. Instead, the earthquake activity rates, as well as the maximum earthquake size stayed proportional to the fluid injection rate. The spatio‐temporal behavior of seismicity and its properties suggest earthquakes occurred not on a single fault, but in a distributed network of similarly oriented fractures, limiting the possibility for occurrence of violent earthquakes. The performed study provides evidence that the induced seismicity due to injection performed within St1 Deep Heat project is stable and allow to constrain seismic hazard.
    Description: Key Points: Induced seismicity associated with stimulation campaign in a 5.8 km deep geothermal OTN‐2 well passively responds to injection operations. Seismicity is a non‐stationary Poisson process with seismicity rate and maximum magnitude modulated by the hydraulic energy input rate. Seismicity clusters in space and time in response to fluid injection but no interaction between earthquakes is observed.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: https://doi.org/10.5880/GFZ.4.2.2022.001
    Keywords: ddc:551.22 ; induced seismicity ; hydraulic stimulation ; earthquake clustering ; earthquake interactions ; Poissonian distribution ; magnitude correlations ; interevent times
    Language: English
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    Bergrecht von Freiberg A (2022)
    Details
    Publication Date: 2022-11-21
    Description: Dieser als Freiberger Bergrecht A oder Älteres Freiberger Bergrecht bezeichneter Gesetzestext, ist wahrscheinlich um das Jahr 1307 und damit kurz nach der Niederschrift des Freiberger Stadtrechtes entstanden. Das Freiberger Bergrecht A war allerdings kein neu entstandenes Gesetz, sondern eine Sammlung älterer Bergrechtstexte.
    Description: source
    Keywords: ddc:622 ; ddc:343.077 ; Markgraf von Meißen ; Freiberg ; Silberbergbau ; Bergrecht
    Language: German
    Type: doc-type:book , updatedVersion
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    Testing the use of the silica deposition fluorescent probe PDMPO to estimate in situ growth rates of diatoms (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-12-07
    Description: The fluorophore [2‐(4‐pyridyl)‐5{[4‐dimethylaminoethyl‐aminocarbamoyl‐methoxy]phenyl}oxazole], in short PDMPO, is incorporated in newly polymerized silica in diatom frustules and thereby provides a tool to estimate Si uptake, study diatom cell cycles but also determine mortality‐independent abundance‐based species specific‐growth rates in cultures and natural assemblages. In this study, the theoretical framework and applicability of the PDMPO staining technique to estimate diatom species specific‐growth rates were investigated. Three common polar diatom species, Pseudo‐nitzschia subcurvata, Chaetoceros simplex, and Thalassiosira sp., chosen in order to cover a broad range of species specific frustule and life‐cycle characteristics, were incubated over 24 h in control (no PDMPO) and with 0.125 and 0.6 μM PDMPO addition, respectively. Results indicate that specific‐growth rates of the species tested were not affected in both treatments with PDMPO addition. The specific‐growth rate estimates based on the PDMPO staining patterns (μPDMPO) were comparable and more robust than growth rates estimated from the changes in cell concentrations (μcc). This technique also allowed to investigate and highlight the importance of the illumination cycle (light and dark phases) on cell division in diatoms.
    Keywords: ddc:579.8 ; diatom frustules ; Si uptake ; growth rate estimation
    Language: English
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    Multi‐Ion Oscillitons—Origin of Coherent Magnetospheric EMIC Waves (2022)
    Details
    Publication Date: 2022-12-07
    Description: The recent spacecraft observations by MMS and Van Allen Probes associated with electromagnetic ion cyclotron (EMIC) waves in the Earth magnetosphere emphasize the important role of multi‐ion plasma composition for generation and characteristics of these emissions. We show that main properties of the coherent EMIC waves can be explained with the concept of “multi‐ion oscillitons” (Sauer et al., 2001, https://doi.org/10.1029/2001GL013047). In a plasma with two types of ions of different masses (e.g., protons and oxygen ions), oscillitons arise from the exchange of momentum and energy between the two ion components, with the electromagnetic field acting as a mediator. At frequencies near cross‐over frequencies of different wave modes in the multi‐ion plasma the nonlinear resonance which strongly amplifies the seed unstable mode can be excited. A small phase difference in oscillations of different ion species leads to a nonlinear wave beating and generation of wave packets. The “resonance” frequency is characterized by a local maximum of the phase velocity and the coincidence of phase and group velocity. It is suggested that the oscillitons are triggered by the instability due to the proton temperature anisotropy and may survive outside the source region for long distances. The generation of coherent waves by oscillitons is of a general nature and may contribute to understand the manifold of phenomena in other space plasma environments in which the dynamics of minor ion admixtures cannot be neglected. The concept of oscillitons can also be applied to the momentum exchange between particle groups of the same mass, but different temperature.
    Description: Plain Language Summary: The mode splitting of electromagnetic waves at oblique propagation in plasmas with multiple ion species leads to the creation of gap regions in omega‐k space. In these “forbidden regions” spatially growing waves exist whose nonlinear state represents a new type of solitons. These so‐called oscillitons, first described by Sauer et al. (2001, https://doi.org/10.1029/2001GL013047), arise from momentum and energy exchange between two or more ion components, with the electromagnetic field acting as a mediator. We suggest that multi‐ion oscillitons are the origin of the ion cyclotron electromagnetic waves (EMIC) in the magnetosphere, which have been known for a long time. Valuable insights have recently been gained through improved diagnostics on the satellites MMS and Van Allen Probes.
    Description: Key Points: Mode coupling of obliquely propagating waves in the range of the ion cyclotron frequencies is a characteristic feature in multi‐ion plasmas. Spatially growing waves may exist in the “forbidden (omega.k) areas” which arise as result of mode coupling. Magnetospheric electromagnetic ion cyclotron waves can be explained by multi‐ion oscillitons (Hall‐MHD solitons superimposed by spatially oscillating structures).
    Keywords: ddc:538.7 ; origin of EMIC waves ; multi‐ion oscillitons ; nonlinear waves ; Hall‐MHD equations
    Language: English
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    Chemical Geodynamics Insights From a Machine Learning Approach (2022)
    Details
    Publication Date: 2022-12-07
    Description: The radiogenic isotope heterogeneity of oceanic basalts is often assessed using 2D isotope ratio diagrams. But because the underlying data are at least six dimensional (87Sr/86Sr, 143Nd/144Nd, 176Hf/177Hf, and 208,207,206Pb/204Pb), it is important to examine isotopic affinities in multi‐dimensional data space. Here, we apply t‐distributed stochastic neighbor embedding (t‐SNE), a multi‐variate statistical data analysis technique, to a recent compilation of radiogenic isotope data of mid ocean ridge (MORB) and ocean island basalts (OIB). The t‐SNE results show that the apparent overlap of MORB‐OIB data trends in 2‐3D isotope ratios diagrams does not exist in multi‐dimensional isotope data space, revealing that there is no discrete “component” that is common to most MORB‐OIB mantle sources on a global scale. Rather, MORB‐OIB sample stochastically distributed small‐scale isotopic heterogeneities. Yet, oceanic basalts with the same isotopic affinity, as identified by t‐SNE, delineate several globally distributed regional domains. In the regional geodynamic context, the isotopic affinity of MORB and OIB is caused by capturing of actively upwelling mantle by adjacent ridges, and thus melting of mantle with similar origin in on, near, and off‐ridge settings. Moreover, within a given isotopic domain, subsidiary upwellings rising from a common deep mantle root often feed OIB volcanism over large surface areas. Overall, the t‐SNE results define a fundamentally new basis for relating isotopic variations in oceanic basalts to mantle geodynamics, and may launch a 21st century era of “chemical geodynamics.”
    Description: Plain Language Summary: The isotopic heterogeneity of basalts erupted at mid ocean ridges (MORB) and ocean islands (OIB) reflects the chemical evolution of Earth's mantle. The visual inspection of various 2D isotope ratio diagrams has fueled a four decade‐long discussion whether basalt heterogeneity reflects melting of only a small number of mantle components, and in particular, whether the apparent overlap of local data trends in global 2D isotope ratio diagrams indicates that melting of a common mantle component contributes to most MORB‐OIB. Here, we use multi‐variate statistical data analysis to show that the apparent overlap of MORB‐OIB data trends in 2D isotope ratio diagrams does not exist in multi‐dimensional isotope data space. Our finding invalidates any inference made for mantle compositional evolution based on the previously proposed existence of a common mantle component, its potential nature or distribution within the mantle. Rather, global MORB‐OIB sample small‐scale isotopic heterogeneities that are distributed stochastically in the Earth's mantle. Yet, MORB‐OIB with the same isotopic affinity, as identified by our multi‐variate data analysis, delineate several globally distributed regional domains. Within the regional geodynamic context, this discovery forms a fundamentally new basis for relating isotopic variations in MORB‐OIB to mantle geodynamics.
    Description: Key Points: Multi‐variate statistical data analysis (t‐distributed stochastic neighbor embedding) identifies global Sr‐Nd‐Hf‐Pb isotopic affinities of oceanic basalts. There is no “common mantle component;” rather, global mid ocean ridge‐ocean island basalts sample stochastically distributed small‐scale isotopic heterogeneities. Globally distributed regional domains of isotopically alike oceanic lavas define a new basis for relating isotopic variations to geodynamics.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung http://dx.doi.org/10.13039/501100001711
    Description: DAAD, German Academic Exchange Service
    Description: https://doi.org/10.25625/0SVW6S
    Description: https://doi.org/10.25625/BQENGN
    Keywords: ddc:551.9 ; mantle heterogeneity ; MORB ; OIB ; geodynamics ; t‐SNE ; radiogenic isotopes ; machine learning
    Language: English
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    Tropical Instability Waves and Wind‐Forced Cross‐Equatorial Flow in the Central Atlantic Ocean (2022)
    Details
    Publication Date: 2022-12-07
    Description: Based on velocity data from a long‐term moored observatory located at 0°N, 23°W we present evidence of a vertical asymmetry during the intraseasonal maxima of northward and southward upper‐ocean flow in the equatorial Atlantic Ocean. Periods of northward flow are characterized by a meridional velocity maximum close to the surface, while southward phases show a subsurface velocity maximum at about 40 m. We show that the observed asymmetry is caused by the local winds. Southerly wind stress at the equator drives northward flow near the surface and southward flow below that is superimposed on the Tropical Instability Wave (TIW) velocity field. This wind‐driven overturning cell, known as the Equatorial Roll, shows a distinct seasonal cycle linked to the seasonality of the meridional component of the south‐easterly trade winds. The superposition of vertical shear of the Equatorial Roll and TIWs causes asymmetric mixing during northward and southward TIW phases.
    Description: Plain Language Summary; Tropical Instability Waves (TIWs) are clear in satellite measurements of sea surface temperature as horizontal undulations with wavelength of the order of 1,000 km in equatorial regions of both Atlantic and Pacific Oceans. TIWs are characterized by their distinctive upper‐ocean meridional velocity structure. TIWs amplify vertical shear and thus contribute to the generation of turbulence which in turn leads to the mixing of heat and freshwater downward into the deeper ocean. In this study we show that the prevailing southerly winds in the central equatorial Atlantic drive near‐surface northward and subsurface southward flows, which are superposed on the meridional TIW velocity field. The strength of this wind driven cell is linked to the seasonal cycle of the northward component of the trade winds, peaking in boreal fall when TIWs reach their maximum amplitude. The overturning cell affects the vertical structure of the meridional velocity field and thus has impact on the generation of current shear and turbulence. We show that the overturning reduces/enhances shear during northward/southward TIW flow, an asymmetry that is consistent with independent measurements showing asymmetric mixing.
    Description: Key Points: Composites of Tropical Instability Waves at 0°N, 23°W show a surface (subsurface) velocity maximum during northward (southward) phases. Meridional wind stress forces a seasonally‐varying, shallow cross‐equatorial overturning cell‐the Equatorial Roll. The superposition of Tropical Instability Waves and Equatorial Roll causes asymmetric mixing during north‐ and southward phases.
    Description: EU H2020
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: US NSF
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Oceanic and Atmospheric Administration http://dx.doi.org/10.13039/100000192
    Description: National Academy of Sciences http://dx.doi.org/10.13039/100000209
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.pangaea.de/10.1594/PANGAEA.941042
    Description: https://www.pmel.noaa.gov/tao/drupal/disdel/
    Keywords: ddc:551.5 ; tropical instability waves ; equatorial Atlantic ; equatorial roll ; moored velocity data ; ocean mixing ; ocean observations
    Language: English
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    Reversals in Temperature‐Precipitation Correlations in the Northern Hemisphere Extratropics During the Holocene (2022)
    Herzschuh, Ulrike ; Böhmer, Thomas ; Li, Chenzhi ; [et al.]
    Details
    Publication Date: 2022-12-07
    Description: Future precipitation levels remain uncertain because climate models have struggled to reproduce observed variations in temperature‐precipitation correlations. Our analyses of Holocene proxy‐based temperature‐precipitation correlations and hydrological sensitivities from 2,237 Northern Hemisphere extratropical pollen records reveal a significant latitudinal dependence and temporal variations among the early, middle, and late Holocene. These proxy‐based variations are largely consistent with patterns obtained from transient climate simulations (TraCE21k). While high latitudes and subtropical monsoon areas show mainly stable positive correlations throughout the Holocene, the mid‐latitude pattern is temporally and spatially more variable. In particular, we identified a reversal from positive to negative temperature‐precipitation correlations in the eastern North American and European mid‐latitudes from the early to mid‐Holocene that mainly related to slowed down westerlies and a switch to moisture‐limited convection under a warm climate. Our palaeoevidence of past temperature‐precipitation correlation shifts identifies those regions where simulating past and future precipitation levels might be particularly challenging.
    Description: Plain Language Summary: Predicting future precipitation levels reliably is more challenging than predicting temperature change. Accordingly, we need to understand the relationship between temperature and precipitation and its changes in space and time. We used climate proxy‐data derived from 2,237 pollen records from lake sediments and peats from the Northern Hemisphere extratropics for the early, middle, and late Holocene (i.e., 12,000–8,000, 8,000–4,000, 4,000–0 years before present, respectively). Our results reveal a significant latitudinal dependence and temporal variation of the temperature‐precipitation relationship. These proxy‐based variations are largely consistent with patterns obtained from simulations using climate models. While high latitudes and subtropical monsoon areas show mainly stable positive correlations throughout the Holocene (i.e., warm conditions co‐occur with wet conditions), the mid‐latitude pattern is temporally and spatially more variable. In particular, we identified a reversal to negative temperature‐precipitation correlations in the eastern North American and European mid‐latitudes from the early to middle Holocene. We hypothesize that weak westerly circulation, warm climate, and climate‐soil feedbacks limited evaporation and as such reduced convection during the middle Holocene which led to a negative relationship between temperature and precipitation. Our analysis of past temperature‐precipitation correlation shifts identifies regions where past changes in the temperature‐precipitation relationships are variable and thus where predicting precipitation might be particularly challenging in a warming climate.
    Description: Key Points: We analyzed Holocene temperature‐precipitation correlations and hydrological sensitivities using climate proxy (pollen) and model data from Northern Hemisphere extratropics. We found reversals to negative temperature‐precipitation correlations from the cold early Holocene to the warm mid‐Holocene likely related to moisture‐limited convection. Correlations and hydrological sensitivities were mostly stable positive in polar and extratropical monsoon‐areas.
    Description: EC European Research Council http://dx.doi.org/10.13039/501100000781
    Description: PALMOD
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Description: https://doi.pangaea.de/10.1594/PANGAEA.930512
    Description: https://doi.org/10.5281/zenodo.5910989
    Description: https://zenodo.org/record/7038402%23.YxBL1uzP3V8
    Keywords: ddc:551 ; ddc:561 ; Holocene ; pollen ; Northern Hemisphere ; temperature-precipation correlations
    Language: English
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    Constraining Andean Propagation of Exhumation at the Limit of the Eastern Cordillera, NW Argentina, Using Low‐Temperature Thermochronology in a Structural Context (2022)
    Details
    Publication Date: 2022-12-07
    Description: Within the Central Andes of NW Argentina, the spatiotemporal distribution and style of deformation is strongly influenced by pre‐Cenozoic heterogeneities, mostly related to the Salta rift extension in the Cretaceous. At the enigmatic junction of the thin‐skinned Subandean belt and the thick‐skinned Santa Barbara System, the Tilcara Range and adjacent San Lucas block, located within the Eastern Cordillera, show thermochronological and field evidence of multiple exhumation events. Mesozoic (140‐115 Ma), pre‐Andean exhumation of basement highs is constrained by unconformities between basement and syn‐rift strata, as well as zircon (U‐Th‐Sm)/He cooling ages. Cenozoic Andean exhumation is quantified by apatite (U‐Th‐Sm)/He and fission track cooling ages, which were reset between the Late Cretaceous and Miocene. These data show that the westernmost Tilcara Range began exhuming in the late Oligocene‐early Miocene (26‐16 Ma), after which exhumation propagated to the border of the Eastern Cordillera in the middle Miocene (22‐10 Ma). The onset of rapid exhumation in the San Lucas block, which is located east of the Tilcara Range, occurred in the late Miocene (10‐8 Ma) in its western part, and in the late Miocene‐early Pliocene (6‐4 Ma) in its eastern part. Internal deformation of the San Lucas block, disturbing zircon (U‐Th‐Sm)/He and apatite fission track age patterns, predates propagation of rapid exhumation. The here presented low‐temperature thermochronology data set thus quantifies the multi‐phase exhumation history of the Eastern Cordillera of NW Argentina and constrains the timing of Andean propagation of exhumation within the Eastern Cordillera and the adjacent structural transition zone.
    Description: Key Points: Zircon (U‐Th‐Sm)/He data suggests that pre‐Andean exhumation of Salta rift basement highs occurred in the Early Cretaceous (140‐115 Ma). Apatite (U‐Th‐Sm)/He and fission track data indicate a late Oligocene‐early Miocene (26‐16 Ma) onset of exhumation in the Tilcara Range. Andean exhumation overall propagated in‐sequence eastward, but thermal models indicate the possibility of local out‐of‐sequence movement.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6358993
    Keywords: ddc:551.8 ; low‐temperature thermochronology ; thermal modeling ; structural geology ; Central Andes ; Eastern Cordillera ; Cenozoic
    Language: English
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    Stochastic Modeling Approach to Identify Uncertainties of Karst Conduit Networks in Carbonate Aquifers (2022)
    Details
    Publication Date: 2022-12-07
    Description: The characterization of the karst conduit network is an essential task to understand the complex flow system within karst aquifers. However, this task is challenging and often associated with uncertainty. Equivalent porous media approaches for modeling flow in karst aquifers fall short of capturing the hydraulic effect of individual karst features, while process‐oriented karst evolution models imply major computational efforts. In this study, we apply the Stochastic Karst Simulator (SKS) developed by Borghi et al. (2012) to generate karst conduit networks at a regional scale of a highly karstified carbonate aquifer located in the Eastern Mediterranean region and extensively used for water supply. The SKS generates conduit network geometries reasonably quick, using a mathematical proxy that mimics conduit evolution. The conduit simulation is based on a conceptual model of the genesis of the aquifer, consisting of different karstification phases. The stochastic approach of the algorithm enables us to generate an ensemble of conduit network realizations and to represent the uncertainties of these simulations in a Karst Probability Map. With only soft input information to constrain conduit evolution, multiple equivalent realizations yield similar resulting network geometries, indicating a robust approach. The presented methodology is numerically efficient, and its input can be easily adjusted. Subsequently, the resulting stochastic spatial distribution of conductivities can be employed for the parametrization of regional karst groundwater models.
    Description: Key Points: We statistically generate multiple sets of karst conduit network geometries using input data based on soft information. The resulting Karst Probability Map accounts for uncertainty in the spatial distribution of the karst conduit network. Our approach can assist in the integration of soft information into the parametrization of karst groundwater models.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.14279/depositonce-16021
    Keywords: ddc:551 ; karst conduit modeling ; stochastic modeling ; structural uncertainty ; karst probability mapping ; groundwater modeling
    Language: English
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    Wiechert’sche Erdbebenwarte Göttingen - Auswertung seismischer Daten als Thema einer Facharbeit (2022)
    Details
    Publication Date: 2022-12-08
    Description: Während der Corona-Pandemie schrieb der Schüler Pascal Schmitt mit Unterstützung des Vereins Wiechert'sche Erdbebenwarte Göttingen e.V.  im "Homeschooling" eine Facharbeit über die Auswertung seismischer Daten. Darin werden einige Daten eines Nah- und eines Fernbebens analysiert, die in Göttingen an der modernen Station GTTG (STS-2-Seismometer) und der historischen Station GTT (Wiechert-Seismographen) registriert wurden - nah und fern, neu und alt werden miteinander verglichen.
    Description: DFG, SUB Göttingen
    Description: research
    Keywords: ddc:551.22 ; ddc:550 ; GTT ; GTTG ; STS-2-Seismometer ; Wiechert-Seismographen ; Nahbeben ; Vergleiche
    Language: German
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    Luise Charlotte Lammert (1887–1946) – Schriftführerin bei der DGG-Gründung 1922 in Leipzig (2022)
    Details
    Publication Date: 2022-12-08
    Description: Aus Anlass des 100. Jahrestages der Gründung der Deutschen Geophysikalischen Gesellschaft im Jahre 1922 in Leipzig erschien 2019 im Verlag Edition am Gutenbergplatz Leipzig das Taschenbuch „Wiechert, Mintrop & Co. – Die 24 Gründungsväter der Deutschen Geophysikalischen Gesellschaft“ von Franz Jacobs und Michael Börngen (s. gleichlautenden Archivbeitrag in DGG-Mitteilungen, 1/2019: 36–37 sowie das anbei dargestellte Titelblatt des Buches). Die damalige Präsidentin und heutige Vize-Präsidentin der DGG, Heidrun Kopp, hat mit einem Geleitwort beigetragen. Das Buch kann über den Buchhandel unter ISBN 978-3-95922-107-8 bestellt werden. Der folgende Artikel erinnert an die Meteorologin Luise Lammert, Schriftführerin der Versammlung, auf der der Gründungsbeschluss gefasst wurde.
    Description: DFG, SUB Göttingen
    Description: research
    Keywords: ddc:550 ; Luise Charlotte Lammert
    Language: German
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    Emil Johannes Wiechert (1861-1928) – Initiator der DGG-Gründung und Erster Vorsitzender 1922 sowie Ehrenvorsitzender 1925 (2022)
    Details
    Publication Date: 2022-12-09
    Description: Aus Anlass des 100. Jahrestages der Gründung der Deutschen Geophysikalischen Gesellschaft im Jahre 1922 in Leipzig erschien im Verlag Edition am Gutenbergplatz Leipzig das Buch „Wiechert, Mintrop & Co. – Die 24 Gründungsväter der Deutschen Geophysikalischen Gesellschaft“ von Franz Jacobs und Michael Börngen (siehe gleichlautenden Archivbeitrag in DGG-Mitteilungen 1/2019: 36-37). Die damalige DGG-Präsidentin Heidrun Kopp hat darin das Geleitwort geschrieben. Das Buch kann über den Buchhandel unter ISBN 978-3-95922-107-8 bestellt werden. Der folgende Artikel ist eine leicht erweiterte Fassung eines Kapitels aus diesem Buch.
    Description: DFG, SUB Göttingen, GFZ Potsdam
    Description: research
    Keywords: ddc:550.9 ; DGG ; Erdbebenforschung
    Language: German
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    Bergordnung Kaiser Maximilian I. für Vorderösterreich (2022)
    Details
    Publication Date: 2022-12-09
    Description: Diese Bergordnung wurde am 22. Mai 1517 von Maximilian I., Römisch deutscher Kaiser und König sowie Erzherzog von Österreich, für Vorderösterreich erlassen. Genannt wurden der Elsaß, Sundgau, Breisgau und der Schwarzwald. Die Bergordnung basiert auf der Bergordnung von Niederösterreich vom 5. Januar 1517 sowie der Annaberger Bergordnung von 5. Februar 1509.
    Description: SUB Göttingen
    Description: source
    Keywords: ddc:557.1 ; ddc:943.6 ; ddc:622 ; Maximilian I. ; Friedrich III. von Sachsen ; Vorderösterreich ; Niederösterreich ; Schwarzwald ; Breisgau ; Elsaß ; Sundgau ; Freiburg im Breisgau ; Annaberg ; Ensisheim ; Schwaz ; Hall ; Linz ; Silberbergbau ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
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    Wissenschaftler des Münchner Geomagnetischen Observatoriums: Friedrich Bidlingmaier (1875–1914) (2022)
    Details
    Publication Date: 2022-12-09
    Description: Leben und Werk des deutschen Geophysikers und Meteorologen Friedrich Bidlingmaier. In den Jahren 1901-03 nahm er als Physiker an der deutschen Südpolexpedition unter E. von Drygalski teil, dessen Ergebnisse zur Erforschung des Erdmagnetismus beitrugen. Er erfand den Doppelkompass zur Messung der horizontalen geomagnetischen Intensität. Cape Bidlingmaier an der Nordküste von Heard Island im südlichen Indischen Ozean trägt seinen Namen.
    Description: research
    Keywords: ddc:550 ; Geomagnetismus ; Observatorium
    Language: German
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    Non‐Linear Dimensionality Reduction With a Variational Encoder Decoder to Understand Convective Processes in Climate Models (2022)
    Details
    Publication Date: 2022-12-06
    Description: Deep learning can accurately represent sub‐grid‐scale convective processes in climate models, learning from high resolution simulations. However, deep learning methods usually lack interpretability due to large internal dimensionality, resulting in reduced trustworthiness in these methods. Here, we use Variational Encoder Decoder structures (VED), a non‐linear dimensionality reduction technique, to learn and understand convective processes in an aquaplanet superparameterized climate model simulation, where deep convective processes are simulated explicitly. We show that similar to previous deep learning studies based on feed‐forward neural nets, the VED is capable of learning and accurately reproducing convective processes. In contrast to past work, we show this can be achieved by compressing the original information into only five latent nodes. As a result, the VED can be used to understand convective processes and delineate modes of convection through the exploration of its latent dimensions. A close investigation of the latent space enables the identification of different convective regimes: (a) stable conditions are clearly distinguished from deep convection with low outgoing longwave radiation and strong precipitation; (b) high optically thin cirrus‐like clouds are separated from low optically thick cumulus clouds; and (c) shallow convective processes are associated with large‐scale moisture content and surface diabatic heating. Our results demonstrate that VEDs can accurately represent convective processes in climate models, while enabling interpretability and better understanding of sub‐grid‐scale physical processes, paving the way to increasingly interpretable machine learning parameterizations with promising generative properties.
    Description: Plain Language Summary: Deep neural nets are hard to interpret due to their hundred thousand or million trainable parameters without further postprocessing. We demonstrate in this paper the usefulness of a network type that is designed to drastically reduce this high dimensional information in a lower‐dimensional space to enhance the interpretability of predictions compared to regular deep neural nets. Our approach is, on the one hand, able to reproduce small‐scale cloud related processes in the atmosphere learned from a physical model that simulates these processes skillfully. On the other hand, our network allows us to identify key features of different cloud types in the lower‐dimensional space. Additionally, the lower‐order manifold separates tropical samples from polar ones with a remarkable skill. Overall, our approach has the potential to boost our understanding of various complex processes in Earth System science.
    Description: Key Points: A Variational Encoder Decoder (VED) can predict sub‐grid‐scale thermodynamics from the coarse‐scale climate state. The VED's latent space can distinguish convective regimes, including shallow/deep/no convection. The VED's latent space reveals the main sources of convective predictability at different latitudes.
    Description: EC ERC HORIZON EUROPE European Research Council http://dx.doi.org/10.13039/100019180
    Description: Columbia sub‐award 1
    Description: Advanced Research Projects Agency - Energy http://dx.doi.org/10.13039/100006133
    Description: Deutsches Klimarechenzentrum http://dx.doi.org/10.13039/100018730
    Description: National Science Foundation Science and Technology Center Learning the Earth with Artificial intelligence and Physics
    Keywords: ddc:551.5 ; machine learning ; generative deep learning ; convection ; parameterization ; explainable artificial intelligence ; dimensionality reduction
    Language: English
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    A New Method for Determining Fluid Flux at High Pressures Applied to the Dehydration of Serpentinites (2022)
    Details
    Publication Date: 2022-12-06
    Description: A new method to determine fluid flux at high pressures and temperatures has been developed and used to study serpentinites at subduction zone conditions. Drill cores of a natural antigorite‐serpentinite with a strong foliation were used in multi‐anvil experiments in the range of 2–5 GPa and 450–800°C. Fluids released upon dehydration are fixed by the formation of brucite in an adjacent fluid sink. The amount and distribution of brucite serves as a proxy for fluid flow. In our specific setup the sample reacted with the surrounding fluid sink to form an additional layer of olivine, which has the potential to limit fluid flux within our experiments. For conditions prior to serpentine dehydration we used Al(OH)3 as fluid source. Fluid in this experiment did not migrate through the serpentinite, indicating that serpentine has a low diffusivity. The experiments also show that small deviatoric stresses have an influence on the fluid flux and can cause an anisotropic fluid flux. Comparison between the time scales of the determined fluid flux with fluid production rates indicates fluid pressure buildup during dehydration reactions. Adjacent less permeable layers can inhibit fluid flux and cause fluid pressure buildup even at conditions when an interconnected pore space formed.
    Description: Plain Language Summary: Subduction zones are regions where tectonic plates are recycled into the Earth's interior. Prior to subduction, the plates experienced extensive chemical interaction with the ocean water, forming hydrous minerals. Serpentine is an important hydrous mineral that can transport significant amounts of water into the Earth's interior. During subduction both pressure and temperature increase whereby hydrous minerals break down and release their water. The fluid migrates into the overlying mantle wedge, where it accounts for hydration as well as melting processes. The global flux balances would require this process to be very effective. However, it was so far not possible to measure the fluid flux at the subduction zone conditions in laboratories. In this study, we present a new method to determine the fluid flux prior and during dehydration. We found that prior to dehydration, the fluid flux in serpentinites is small. During dehydration the rocks ability to let fluids pass through increases. However, adjacent rocks with a low ability for fluid transport can further inhibit a fluid flux at these conditions. Generally, our experimental setup can be used for any system that immobilizes migrating fluids by hydration reactions.
    Description: Key Points: A new method to determine fluid flux at high pressure and temperature conditions is developed. Slow fluid migration in serpentinites promotes brittle fracturing in subduction zones. Fast fluid migration upon dehydration of serpentinites promotes large‐scale fluid flux, if not inhibited by adjacent less permeable layers.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: JSPS Japanese‐German Graduate Externship
    Description: Nederlandse Organisatie voor Wetenschappelijk Onderzoek http://dx.doi.org/10.13039/501100003246
    Description: https://doi.org/10.24416/UU01-PB440D
    Keywords: ddc:552.4 ; fluid flux ; multi‐anvil ; serpentine ; brucite ; dehydration ; excess pressure
    Language: English
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    Pore Space Topology Controls Ultrasonic Waveforms in Dry Volcanic Rocks (2022)
    Details
    Publication Date: 2022-12-06
    Description: Pore space controls the mechanical and transport properties of rocks. At the laboratory scale, seismic modeling is usually performed in relatively homogeneous settings, and the influence of the pore space on the recorded wavefields is determined by rock‐fluid interactions. Understanding this influence in dry rocks is instrumental for assessing the impact of pore topology on waves propagating in heterogeneous environments, such as volcanoes. Here, we simulated the propagation of shear waves as a function of pore space parameters in computational models built as proxies for volcanic rocks. The spectral‐element simulations provide results comparable with ultrasonic experiments, and the outcome shows that the size, shape, volume, and location of pores impact amplitudes and phases. These variations intensify in waveform coda after multiple scattering. Our results confirm that pore topology is one of the primary regulators of the propagation of elastic waves in dry rocks regardless of porosity.
    Description: Plain Language Summary: Pores control the non‐elastic behavior and, in general, the petrophysical and mechanical properties of rocks. Such properties are essential to assess potential resources such as aquifers and reservoirs or hazards posed by earthquakes, volcanoes, and constructions. The factors controlling the elasticity of rocks are texture, pore space and the fluids filling the pores. While volcanoes represent a key target for rock characterization, measuring and modeling these factors in volcanic rocks remains challenging due to their intrinsic heterogeneities. In this study, we analyzed how pore space parameters influence the overall elastic properties of rocks by changing one parameter at a time. We created synthetic samples and performed computational simulations that show the individual contribution of the amount, size, location, and shape on waveform phases and amplitudes. The findings demonstrate that we can constrain the pore space in heterogeneous rocks in simple but realistic scenarios. Our results are the first step to provide computationaly‐driven forward models of seismic signals in heterogeneous volcanic media, necessary to predict the responses of volcanic rocks to stress.
    Description: Key Points: Computational modeling quantifies the influence of pore space topology on S‐wave propagation in volcanic rocks. Amount, size and location of pores impact ultrasonic wave propagation in dry rocks independently of porosity. Path effects dominate the waveforms and depend on the location of the pores.
    Description: https://doi.org/10.17632/b5p54xtvv9.3
    Keywords: ddc:550.78 ; volcanic rocks ; pore space topology ; S-wave propagation ; computational modeling
    Language: English
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    Site dependence of the magnetocaloric effect in Mn5−xFexSi3 (2022)
    Ait Haddouch, Mohammed ; Abboushi, Nour ; Sharma, Neetika ; [et al.]
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2022-12-06
    Description: The nuclear and magnetic structures of Mn3Fe2Si3 are investigated in the temperature range from 20 to 300 K. The magnetic properties of Mn3Fe2Si3 were measured on a single crystal. The compound undergoes a paramagnetic to antiferromagnetic transition at TN2 ≃ 120 K and an antiferromagnetic to antiferromagnetic transition at TN1 ≃ 69 K. A similar sequence of magnetic phase transitions is found for the parent compound Mn5Si3 upon temperature variation, but the field‐driven transition observed in Mn5Si3 is not found in Mn3Fe2Si3, resulting in a strongly reduced magnetocaloric effect. Structurally, the hexagonal symmetry found for both compounds under ambient conditions is preserved in Mn3Fe2Si3 through both magnetic transitions, indicating that the crystal structure is only weakly affected by the magnetic phase transition, in contrast to Mn5Si3 where both transitions distort the nuclear structure. Both compounds feature a collinear high‐temperature magnetic phase AF2 and transfer into a non‐collinear phase AF1 at low temperature. While one of the distinct crystallographic sites remains disordered in the AF2 phase in the parent compound, the magnetic structure in the AF2 phase involves all magnetic atoms in Mn3Fe2Si3. These observations imply that the distinct sites occupied by the magnetic atoms play an important role in the magnetocaloric behaviour of the family.
    Description: The nuclear and magnetic structures of Mn3Fe2Si3 are determined and the magnetic properties are compared with those of the parent compound Mn5Si3. The results imply that the distinct magnetic sites play an important role in the magnetocaloric behaviour of the family. image
    Keywords: ddc:548 ; magnetocaloric effect ; magnetic structure ; neutron diffraction ; synchrotron diffraction ; site dependence
    Language: English
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    Denitrification‐Driven Transcription and Enzyme Production at the River‐Groundwater Interface: Insights From Reactive‐Transport Modeling (2022)
    Details
    Publication Date: 2022-12-06
    Description: Molecular‐biological data and omics tools have increasingly been used to characterize microorganisms responsible for the turnover of reactive compounds in the environment, such as reactive‐nitrogen species in groundwater. While transcripts of functional genes and enzymes are used as measures of microbial activity, it is not yet clear how they are quantitatively related to actual turnover rates under variable environmental conditions. As an example application, we consider the interface between rivers and groundwater which has been identified as a key driver for the turnover of reactive‐nitrogen compounds, that cause eutrophication of rivers and endanger drinking water production from groundwater. In the absence of measured data, we developed a reactive‐transport model for denitrification that simultaneously predicts the distributions of functional‐gene transcripts, enzymes, and reaction rates. Applying the model, we evaluate the response of transcripts and enzymes at the river‐groundwater interface to stable and dynamic hydrogeochemical regimes. While functional‐gene transcripts respond to short‐term (diurnal) fluctuations of substrate availability and oxygen concentrations, enzyme concentrations are stable over such time scales. The presence of functional‐gene transcripts and enzymes globally coincides with the zones of active denitrification. However, transcript and enzyme concentrations do not directly translate into denitrification rates in a quantitative way because of nonlinear effects and hysteresis caused by variable substrate availability and oxygen inhibition. Based on our simulations, we suggest that molecular‐biological data should be combined with aqueous geochemical data, which can typically be obtained at higher spatial and temporal resolution, to parameterize and calibrate reactive‐transport models.
    Description: Plain Language Summary: Molecular‐biological tools can detect how many enzymes, functional genes, and gene transcripts (i.e., precursors of enzyme production) associated with a microbial reaction exist in a sample from the environment. Although these measurements contain valuable information about the number of bacteria and how active they are, they do not directly say how quickly a contaminant like nitrate disappears. Nitrate, from agriculture and other sources, threatens groundwater quality and drinking water production. In the process of denitrification, bacteria can remove nitrate by converting it into harmless nitrogen gas using specialized enzymes. The interface between rivers and groundwater is known as a place where denitrification takes place. In this study, we use a computational model to simulate the coupled dynamics of denitrification, bacteria, transcripts, and enzymes when nitrate‐rich groundwater interacts with a nearby river. The simulations yield complex and nonunique relationships between the denitrification rates and the molecular‐biological variables. While functional‐gene transcripts respond to daily fluctuations of environmental conditions, enzyme concentrations and genes are stable over such time scales. High levels of functional‐gene transcripts therefore provide a good qualitative indicator of reactive zones. Quantitative predictions of nitrate turnover, however, will require high‐resolution measurements of the reacting compounds, genes, and transcripts.
    Description: Key Points: We simulate the distributions of functional‐gene transcripts and enzymes related to denitrification at the river‐groundwater interface. Functional‐gene transcripts respond quickly to diurnal fluctuations of substrate and oxygen concentrations. Substrate limitation and oxygen inhibition impede the direct prediction of denitrification rates from transcript or enzyme concentrations.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6584591
    Description: https://gitlab.com/astoeriko/nitrogene
    Description: https://doi.org/10.5281/zenodo.6584641
    Description: https://gitlab.com/astoeriko/adrpy
    Description: https://doi.org/10.5281/zenodo.5213947
    Description: https://github.com/aseyboldt/sunode
    Keywords: ddc:551 ; reactive‐transport modeling ; denitrification ; groundwater‐river interface ; functional genes ; transcripts ; molecular biology
    Language: English
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    Life cycle assessment of an industrial‐scale vanadium flow battery (2022)
    Details
    Publication Date: 2022-12-10
    Description: In the course of the energy transition, storage technologies are required for the fluctuating and intermittently occurring electrical energy. The vanadium flow battery (VFB) is an especially promising electrochemical battery type for megawatt applications due to its unique characteristics. This work is intended as a benchmark for the evaluation of environmental impacts of a VFB, providing transparency and traceability. It considers the requirements for an industrial VFB from the technical and electrochemical point of view. The system design is based on a net capacity of 8 MWh and a net power of 1 MW. This ex ante study is a cradle‐to‐grave life cycle assessment (LCA) for a VFB to identify, analyze, and evaluate the environmental impacts for a lifetime of 20 years. Moreover, potential environmental impacts of several subsequent life cycles of the emission‐intensive and long‐lasting vanadium electrolyte are evaluated. With a focus on the electrolyte, the extraction process of vanadium pentoxide is studied in detail for the first time. Consequently, recommendations for the design of the life cycle of VFBs and for comparative LCAs with other energy storage technologies can be derived. Based on this work, more detailed work can follow, which helps to estimate the recycling potentials and emissions more precisely. This article met the requirements for a gold‐gold JIE data openness badge described at https://jie.click/badges
    Description: German Federal Ministry for Economic Affairs and Climate Action
    Keywords: ddc:621.31 ; climate change ; energy storage ; industrial ecology ; life cycle assessment ; vanadium flow battery ; vanadium pentoxide
    Language: English
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    Melt Production and Ejection From Lunar Intermediate‐Sized Impact Craters: Where Is the Molten Material Deposited? (2022)
    Details
    Publication Date: 2022-12-10
    Description: Differently aged impact melt in lunar samples is key to unveiling the early bombardment history of the Moon. Due to the mixing of melt products ejected from distant craters, the interpretations of the origin of lunar samples are difficult. We use numerical modeling for a better quantitative understanding of the production of impact‐induced melt and in particular its distribution in ejecta blankets for lunar craters with sizes ranging from 1.5 to 50 km. We approximate the lunar stratigraphy with a porosity gradient, which represents the gradual transition from upper regolith via megaregolith to the solid crustal material. For this lunar setting, we quantify the melt production relative to crater volume and derive parameters describing its increasing trend with increasing transient crater size. We found that about 30%–40% of the produced melt is ejected from the crater. The melt concentration in the ejecta blanket increases almost linearly with distance from the crater center, while the thickness of the ejecta blanket decreases following a power law. Our study demonstrates that if in lunar samples the concentration of a melt with a certain age is interpreted to be of a nonlocal origin, these melts could be the impact products of a large crater (〉10 km) located hundreds of kilometers away.
    Description: Plain Language Summary: Lunar samples contain abundant impact‐induced melt that crystallized at different ages. The melt ages record the formation time of its source craters and are key for a better understanding of the lunar bombardment history. In samples, there is not only the melt derived from the sampling region but also some that originate far away by being entrained in the ejecta of distant craters. Recognizing the distant‐derived melt is essential for the more credible sample interpretation, which requires knowledge of the melt distribution in the ejecta. We use numerical modeling to quantify the production of impact‐induced melt and in particular its distribution in ejecta blankets for lunar craters. We found that the melt concentration in the ejecta blanket increases with distance from the crater center. If the concentration of distant‐derived melt of a certain age in lunar samples is rather high (〉30%), it could originate from large craters (〉10 km) located hundreds of kilometers away.
    Description: Key Points: The melt concentration in the ejecta blanket increases almost linearly with distance from the crater center. Near‐surface porosity causes an increase in melt production. Due to decreasing porosity with depth, it is more prominent at small craters. The melt concentration in distal ejecta of crater of 10's km is rather high (〉30%).
    Description: Deutsche Forschungsgemeinschaft DFG http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:523 ; lunar craters ; melt production ; numerical modeling
    Language: English
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    Combined seismic and borehole investigation of the deep granite weathering structure—Santa Gracia Reserve case in Chile (2022)
    Details
    Publication Date: 2022-12-10
    Description: Imaging the critical zone at depth, where intact bedrock transforms into regolith, is critical in understanding the interaction between geological and biological processes. We acquired a 500 m‐long near‐surface seismic profile to investigate the weathering structure in the Santa Gracia National Reserve, Chile, which is located in a granitic environment in an arid climate. Data processing comprised the combination of two seismic approaches: (1) body wave tomography and (2) multichannel analysis of surface wave (MASW) with Bayesian inversion. This allowed us to derive P‐wave and S‐wave velocity models down to 90 and 70 m depth, respectively. By calibrating the seismic results with those from an 87 m‐deep borehole that is crossed by the profile. We identified the boundaries of saprolite, weathered bedrock, and bedrock. These divisions are indicated in the seismic velocity variations and refer to weathering effects at depth. The thereby determined weathering front in the borehole location can be traced down to 30 m depth. The modelled lateral extent of the weathering front, however, cannot be described by an established weathering front model. The discrepancies suggest a more complex interaction between different aspects such as precipitation and topography in controlling the weathering front depth.
    Description: Combined seismic approaches of body wave tomography and MASW method revealed the upper 90 m of the critical zone down to the bedrock. The integration of the borehole data with the resulting P‐ and S‐wave velocity model, as well as the vertical velocity gradient model, provides a strong constraint in identifying the different lithologies. The resulting conceptual model shows the extent of the critical zone in Santa Gracia Reserve, Chile and its relation to topography.
    Description: German Science Foundation (DFG) priority research programme SPP‐1803 ‘EarthShape: Earth Surface Shaping by Biota’
    Keywords: ddc:622.15 ; borehole ; geophysics ; Bayesian inversion ; body wave tomography ; critical zone ; geomorphology ; geophysics ; Rayleigh wave ; regolith ; seismic survey ; surface wave tomography ; velocity gradient ; weathering front
    Language: English
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    On the Role of Rheological Memory for Convection‐Driven Plate Reorganizations (2022)
    Details
    Publication Date: 2022-12-10
    Description: Understanding the temporal variability of plate tectonics is key to unraveling how mantle convection transports heat, and one critical factor for the formation and evolution of plate boundaries is rheological “memory,” that is, the persistence of weak zones. Here, we analyze the impact of such damage memory in global, oceanic‐lithosphere‐only models of visco‐plastic mantle convection. Self‐consistently‐formed weak zones are found to be reactivated in distinct ways, and convection preferentially selects such damaged zones for new plate boundaries. Reactivation of damage zones increases the frequency of plate reorganizations, and hence reduces the dominant periods of surface heat loss. The inheritance of distributed lithospheric damage thus dominates global surface dynamics over any local boundary stabilizing effects of weakening. In nature, progressive generation of weak zones may thus counteract and perhaps overcome any effects of reduced convective vigor throughout planetary cooling, with implications for the frequency of orogeny and convective transport throughout Wilson cycles.
    Description: Plain Language Summary: Understanding how and why the motion of the lithosphere changes over time is important since this is telling us how planets with a plate tectonic style of heat transport evolve by thermo‐chemical mantle convection. One important factor for the evolution of plate boundaries is hysteresis, that is, memory of past deformation. Inherited weak zones, such as sutures, and progressive weakening are well documented in the geological record. Convection with damage shows dynamical behavior that is different from pure plastic failure without memory, or homogenous lithosphere that is being newly broken. We analyze the impact of damage with global, oceanic‐lithosphere‐only models of plate‐like mantle convection. Weak zones that are formed in an initially homogenous material are found to be reactivated subsequently in distinct ways. Within our tectonic system model, convection preferentially selects pre‐damaged zones for new, active plate boundaries. This reactivation increases the frequency of plate reorganizations compared to models without damage, and also changes the time‐dependence of cyclic surface heat loss. In nature, the progressive generation of weak zones over planetary history may counteract and perhaps overcome any effects of reduced convective vigor during cooling. This has implications for the frequency of mountain building and understanding Wilson cycles.
    Description: Key Points: Results from global, plate‐generating convection models with damage. Self‐consistently formed persistent weak zones lead to more frequent plate reorganizations. Accumulation of weak zones might counteract decrease in convective vigor for tectonic variability.
    Description: NSF EAR
    Description: Division of Earth Sciences http://dx.doi.org/10.13039/100000160
    Description: https://geodynamics.org/resources/citcoms
    Description: https://doi.org/10.5281/zenodo.6546322
    Keywords: ddc:551 ; plate tectonics ; visco-plastic convection models
    Language: English
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    Imaging the Absorbing Feeding and Eruptive Pathways of Deception Island, Antarctica (2022)
    Details
    Publication Date: 2022-12-10
    Description: Deception Island is one of the most active and best‐documented volcanoes in Antarctica. Since its last eruption in 1970, several geophysical surveys have targeted reconstructing its magmatic systems. However, geophysics fails to reconstruct the pathways magma and fluids follow from depth to erupt at the surface. Here, novel data selection strategies and multi‐frequency absorption inversions have been framed in a Geographical Information System, using all available geological (vents and faults distribution), geochemical and geophysical knowledge of the volcano. The result is the detection of these eruptive pathways. The model offers the first image of the magma and associated fluids pathways feed the 1967, 1969, and 1970 eruptions. Results suggest that future ascending paths might lead to active research bases and zones of planned helicopter rescue. The connection between seismic absorption, temperature, and fluid content makes it a promising attribute for detecting and monitoring eruptions at active calderas.
    Description: Plain Language Summary: Deception Island is the gateway for tourists to Antarctica and a laboratory to understand ice‐capped volcanoes and their eruptions. While the Island has been the target of many geophysical studies, no clear tomographic model shows how deep eruptive pathways of its last eruptions have reached the surface in the 1960s and 1970s. This is a recurrent topic in volcano geophysics: dikes and fluid migrations develop across structures considered too small to be detected by tomographic techniques. This paper demonstrates that seismic absorption has sufficient sensitivity to temperature and fluid content to detect these pathways. Once integrated within a Geographical Information System with all the information we have on the volcano, the models resolve the feeding systems of these eruptions, from a tectonically deformed deep magma chamber to shallow cold dyke intrusions and fluid migrations still feeding the volcano today. The correlation between seismic absorption, temperature, and fluid content offers a new tool for detecting and monitoring shallow volcanic hazards.
    Description: Key Points: High absorption detects deep eruptive pathways from the caldera center to its rim. Absorption imaging reconstructs shallow pathways of hazardous materials. Seismic absorption is sensitive to thermal anomalies at depth.
    Description: https://doi.org/10.5281/zenodo.6561124
    Description: https://zenodo.org/badge/latestdoi/493744216
    Keywords: ddc:551 ; seismic absorption ; seismic tomography ; Deception Island ; Volcanology ; remote sensing
    Language: English
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    Trade‐Offs for Climate‐Smart Forestry in Europe Under Uncertain Future Climate (2022)
    Gregor, Konstantin ; Knoke, Thomas ; Krause, Andreas ; [et al.]
    Details
    Publication Date: 2022-12-10
    Description: Forests mitigate climate change by storing carbon and reducing emissions via substitution effects of wood products. Additionally, they provide many other important ecosystem services (ESs), but are vulnerable to climate change; therefore, adaptation is necessary. Climate‐smart forestry combines mitigation with adaptation, whilst facilitating the provision of many ESs. This is particularly challenging due to large uncertainties about future climate. Here, we combined ecosystem modeling with robust multi‐criteria optimization to assess how the provision of various ESs (climate change mitigation, timber provision, local cooling, water availability, and biodiversity habitat) can be guaranteed under a broad range of climate futures across Europe. Our optimized portfolios contain 29% unmanaged forests, and implicate a successive conversion of 34% of coniferous to broad‐leaved forests (11% vice versa). Coppices practically vanish from Southern Europe, mainly due to their high water requirement. We find the high shares of unmanaged forests necessary to keep European forests a carbon sink while broad‐leaved and unmanaged forests contribute to local cooling through biogeophysical effects. Unmanaged forests also pose the largest benefit for biodiversity habitat. However, the increased shares of unmanaged and broad‐leaved forests lead to reductions in harvests. This raises the question of how to meet increasing wood demands without transferring ecological impacts elsewhere or enhancing the dependence on more carbon‐intensive industries. Furthermore, the mitigation potential of forests depends on assumptions about the decarbonization of other industries and is consequently crucially dependent on the emission scenario. Our findings highlight that trade‐offs must be assessed when developing concrete strategies for climate‐smart forestry.
    Description: Plain Language Summary: Forests help mitigate climate change by storing carbon and via avoided emissions when wood products replace more carbon‐intensive materials. At the same time, forests provide many other “ecosystem services (ESs)” to society. For example, they provide timber, habitat for various species, and they cool their surrounding regions. They are, however, also vulnerable to ongoing climate change. Forest management must consider all these aspects, which is particularly challenging considering the uncertainty about future climate. Here, we propose how this may be tackled by computing optimized forest management portfolios for Europe for a broad range of future climate pathways. Our results show that changes to forest composition are necessary. In particular, increased shares of unmanaged and broad‐leaved forests are beneficial for numerous ESs. However, these increased shares also lead to decreases in harvest rates, posing a conflict between wood supply and demand. We further show that the mitigation potential of forests strongly depends on how carbon‐intensive the replaced materials are. Consequently, should these materials become “greener” due to new technologies, the importance of wood products in terms of climate change mitigation decreases. Our study highlights that we cannot optimize every aspect, but that trade‐offs between ESs need to be made.
    Description: Key Points: Strategies for climate‐smart forestry under a range of climate scenarios always lead to trade‐offs between different ecosystem services (ESs). Higher shares of unmanaged and broad‐leaved forests are beneficial for numerous ESs, but lead to decreased timber provision. The mitigation potential of forests strongly relies on substitution effects which depend on the carbon‐intensity of the alternative products.
    Description: European Forest Institute (EFI) Networking Fund http://dx.doi.org/10.13039/501100013942
    Description: Bayerisches Staatsministerium für Wissenschaft und Kunst, Bayerisches Netzwerk für Klimaforschung (BayKliF) http://dx.doi.org/10.13039/501100004563
    Description: Swedish Research Council Formas
    Description: German Federal Office for Agriculture and Food (BLE)
    Description: https://doi.org/10.5281/zenodo.6667489
    Description: https://doi.org/10.5281/zenodo.6612953
    Keywords: ddc:634.9 ; forest management ; climate change mitigation ; substitution effects ; climate‐smart forestry ; ecosystem services ; robust optimization
    Language: English
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    Numerical Modeling of Structurally Controlled Ore Formation in Magmatic‐Hydrothermal Systems (2022)
    Details
    Publication Date: 2022-12-10
    Description: Faults and fractures can be permeable pathways for focused fluid flow in structurally controlled ore‐forming hydrothermal systems. However, quantifying their role in fluid flow on the scale of several kilometers with numerical models typically requires high‐resolution meshes. This study introduces a modified numerical representation of m‐scale fault zones using lower‐dimensional elements (here, one‐dimensional [1D] elements in a 2D domain) to resolve structurally controlled fluid flow with coarser mesh resolutions and apply the method to magmatic‐hydrothermal ore‐forming systems. We modeled horizontal and vertical structure‐controlled magmatic‐hydrothermal deposits to understand the role of permeability and structure connectivity on ore deposition. The simulation results of vertically extended porphyry copper systems show that ore deposition can occur along permeable vertical structures where ascending, overpressured magmatic fluids are cooled by downflowing ambient fluids. Structure permeability and fault location control the distribution of ore grades. In highly permeable structures, the mineralization can span up to 3 km vertically, resulting in heat‐pipe mechanisms that promote the ascent of a magmatic vapor phase to an overlying structurally controlled epithermal system. Simulations for the formation of subhorizontal vein‐type deposits suggest that the major control on fluid flow and metal deposition along horizontal structures is the absence of vertical structures above the injection location but their presence at greater distances. Using a dynamic permeability model mimicking crack‐seal mechanisms within the structures leads to a pulsating behavior of fracture‐controlled hydrothermal systems and prevents the inflow of ambient fluids under overpressured conditions.
    Description: Plain Language Summary: Faults and fractures can serve as permeable pathways for focused fluid flow in the subsurface and therefore be essential geological features for the formation of economic mineral deposits. However, quantifying their role in the hydrothermal systems on the scale of several kilometers with numerical models typically requires high‐resolution meshes. This study presents a modified numerical representation of m‐scale fault zones with variable orientations to understand the hydrology of magmatic‐hydrothermal ore‐forming systems. The vertically extended systems simulation results show that ore deposition can occur along permeable vertical structures where ascending magmatic fluids are cooled by downflowing ambient fluids. Structure permeability and fault location can directly control the distribution of ore grades. In contrast, mineralization in horizontal structures requires the absence of vertical structures above the injection location of metal‐bearing magmatic volatiles but their presence at greater distances. Our model also shows how dynamic opening and closing of the structures in response to magmatic degassing can lead to a pulsating behavior and prevent the downflow of ambient fluids.
    Description: Key Points: We describe structurally controlled fluid flow by representing faults and fractures as one‐dimensional line elements within a 2D modeling domain. Vertical structures are efficient pathways for focused fluid flow and formation of high‐grade mineralization. Ore formation in horizontal fractures requires a hydraulic connection to distal vertical fault zones.
    Description: German Federal Ministry of Education and Research
    Description: Deutsche Forschungsgemeinschaft, DFG http://dx.doi.org/10.13039/501100001659
    Description: Helmholtz Recruitment Initiative
    Keywords: ddc:551 ; magmatic‐hydrothermal systems ; ore deposits ; fluid flow ; numerical simulations ; faults and fractures
    Language: English
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    Die Hamelner Altstadtsanierung 1964 – 1992/2018 (2022)
    Details
    Publication Date: 2022-12-21
    Description: Hameln ist ein früher Modellfall bundesdeutscher Reformen in der Städtepolitik in den 1960er Jahren und beispielhaft für die Korrektur der Sanierungsziele hin zur Objektsanierung Mitte der 1970er Jahre. Räumliche Planung reorganisiert die Flächennutzung zur Sicherung und Förderung des Gemeinwohls. Worin das Gemeinwohl jeweils besteht, wie es verhandelt wird und wer es bestimmt, wird an der Festlegung der wechselnden Sanierungsziele und ihrer kommunalpolitischen Durchsetzung dargestellt. Die Entdeckung und Beseitigung innerstädtischer Wachstumshindernisse wird deutlich von über-kommunalen Entwicklungen bestimmt, von den Zielen nationaler Siedlungs- und Städtebauförderpolitik, von den ökonomischen Tendenzen der Cityentwicklung und damit zusammenhängend von den jeweils herrschenden Planungsparadigmen. Stadtplanerische Interventionen beheben die Widersprüche der Gemeinwohlpolitik nur vorübergehend, wie die Cityentwicklung in Hameln nach dem offiziellen Ende der Sanierung 1992 zeigt.
    Description: research
    Keywords: ddc:307.1216 ; ddc:307.3416 ; Stadtplanung ; Hameln ; Gemeinwohl ; Cityentwicklung ; Kommunalpolitik ; Stadtsanierung ; Städtebauförderung
    Language: German
    Type: doc-type:book
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    Bergordnung Herzog Friedrich IV. von Österreich für Gossensaß (2022)
    Details
    Publication Date: 2022-12-22
    Description: Diese Bergordnung wurde am 26. Juni 1427 für die Bergwerke in Gossensaß von Herzog Friedrich IV. von Österreich, Steiermark und Kärnten sowie Herr zu Krain und Pfirt, Graf zu Tirol und Kyburg, Landgraf zu Elsaß und Markgraf zu Burgau erlassen. In der Einleitung wurde darauf hingewiesen, dass diese Bergordnung zwei Jahre gelten sollte. Im Anschluss wurden die zehn eingesetzten Geschworenen namentlich aufgeführt. Erklärt wurden die Holzrechte, die Entlohnung der im Bergbau Beschäftigten und das Verbot Waffen zu tragen.
    Description: source
    Keywords: ddc:557.1 ; ddc:622 ; ddc:343.077 ; Friedrich IV. von Österreich ; Österreich ; Steiermark ; Kärnten ; Tirol ; Elsaß ; Gossensaß ; Sterzing ; Schladming ; Silberbergbau ; Bergordnung
    Language: German
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    Bergordnung Kurfürst Friedrich II. für Ehrenfriedersdorf 1450 (2022)
    Details
    Publication Date: 2022-12-22
    Description: Diese Bergordnung lies Kurfürst Friedrich II. von Sachsen von seinen Amtleuten, Richtern, Schöffen und den ältesten Bergleuten von Ehrenfriedersdorf, Geyer und Thum auf der Grundlage des alten praktizierten Rechtes erstellen. In ihr wurden die Verleihpraxis durch den Bergmeister, die Größe der Grubenfelder, das gültige Stollenrecht sowie die Fristen bei der Verleihung und dem Betrieb der Gruben beschrieben. Neben dem Bergbau auf Zinn wurden auch die Rechte der Zinnseifen genannt sowie die Handlungen und Kosten des Zinnverkaufs beschrieben.
    Description: source
    Keywords: ddc:343.077 ; ddc:622 ; ddc:557.1 ; Kurfürst Friedrich II. von Sachsen ; Hans Schocher Vogt von Scharfenstein ; Ehrenfriedersdorf ; Geyer ; Thum ; Zinnbergbau ; Sachsen ; Bergordnung
    Language: German
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    Probability Distributions of Radiocarbon in Open Linear Compartmental Systems at Steady‐State (2022)
    Details
    Publication Date: 2022-06-26
    Description: Radiocarbon (14C) is commonly used as a tracer of the carbon cycle to determine how fast carbon moves between different reservoirs such as plants, soils, rivers, or oceans. However such studies mostly emphasize the mean value (as Δ14C) of an unknown probability distribution. We introduce a novel algorithm to compute Δ14C distributions from knowledge of the age distribution of carbon in linear compartmental systems at steady‐state. Our results demonstrate that the shape of the distributions might differ according to the speed of cycling of ecosystem compartments and their connectivity within the system, and might contain multiple peaks and long tails. The distributions are also sensitive to the variations of Δ14C in the atmosphere over time, as influenced by the counteracting anthropogenic effects of fossil‐fuel emissions (14C‐free) and nuclear weapons testing (excess 14C). Lastly, we discuss insights that such distributions can offer for sampling and design of experiments aiming to capture the precise variance of Δ14C values present in the multi‐compartmental ecosystems.
    Description: Plain Language Summary: Radiocarbon (14C) is a radioactive isotope of carbon prominent in environmental sciences for tracing the dynamics of ecosystems, especially as recent changes in atmospheric radiocarbon allow tracking excess 14C created by nuclear weapons testing in the atmosphere on timescales shorter than what can be determined using radioactive decay. For climate change mitigation, a crucial uncertainty is the time carbon captured through photosynthesis spends in ecosystems before being released. For this purpose, radiocarbon can be valuable as a biological tracer; however, it is necessary to accurately link the real age of carbon and its radiocarbon age, as they usually differ. Forests and soils are open systems, connecting components with intrinsically different cycling timescales, so that the mean age comes from an age distribution that is usually unknown. Here, we developed an algorithm to compute the 14C contents for models consisting of multiple interconnected carbon pools. Our approach offers more accurate estimations of the mean 14C content of the system and computations of the distribution of 14C within the system at different points in time. Results obtained from this method can provide additional insights on the dynamics of the carbon cycle in multiple compartments, and can help to better interpret observations.
    Description: Key Points: Probability distributions of radiocarbon in ecosystem compartments can be derived from carbon age distributions. The shape of these distributions vary according to the speed of carbon cycling and the year of observation. Probability distributions of radiocarbon provide insights to study carbon dynamics and to interpret radiocarbon data.
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: Max‐Planck‐Gesellschaft (MPG) http://dx.doi.org/10.13039/501100004189
    Description: https://doi.org/10.5281/zenodo.6373329
    Keywords: ddc:551.9
    Language: English
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    A Combined Cosmogenic Nuclides Approach for Determining the Temperature‐Dependence of Erosion (2022)
    Details
    Publication Date: 2022-06-26
    Description: Physical weathering in cold, steep bedrock hillslopes occurs at rates that are thought to depend on temperature, but our ability to quantify the temperature‐dependence of erosion remains limited when integrating over geomorphic timescales. Here, we present results from a 1D numerical model of in‐situ cosmogenic 10Be, 14C, and 3He concentrations that evolve as a function of erosion rate, erosion style, and ground surface temperature. We used the model to explore the suitability of these nuclides for quantifying erosion rates in areas undergoing non‐steady state erosion, as well as the relationship between bedrock temperature, erosion rate, and erosional stochasticity. Our results suggest that even in stochastically eroding settings, 10Be‐derived erosion rates of amalgamated samples can be used to estimate long‐term erosion rates, but infrequent large events can lead to bias. The ratio of 14C to 10Be can be used to evaluate erosional stochasticity, and to determine the offset between an apparent 10Be‐derived erosion rate and the long‐term rate. Finally, the concentration of 3He relative to that of 10Be, and the paleothermometric interpretations derived from it, are unaffected by erosional stochasticity. These findings, discussed in the context of bedrock hillslopes in mountainous regions, indicate that the 10Be‐14C‐3He system in quartz offers a method to evaluate the temperature‐sensitivity of bedrock erosion rates in cold, high‐alpine environments.
    Description: Plain Language Summary: All mountains erode, but not all mountains erode in the same way and at the same rate. In cold mountainous landscapes, temperature is thought to be an important control on erosion. Previous research suggests that rocks fracture by frost most effectively at temperatures between −3°C and −8°C, and that the warming and thawing of permanently frozen ground (permafrost) destabilizes hillslopes and leads to more and larger rockfalls. However, our ability to test these hypotheses is limited, due to difficulties in measuring or estimating erosion rates and linking them with the temperatures that rocks experience. In this paper we present the results of a computer modeling study that tests the suitability of geochemical tools as measures of erosion rate, erosion style, and long‐term bedrock temperature. We find that these geochemical tracers, called cosmogenic nuclides, can be used to determine erosion rates, even in places that are prone to rare rockfalls, together with the long‐term bedrock temperature. They are therefore uniquely suitable for evaluating the link between temperatures and erosion rates in cold bedrock hillslopes over long timescales.
    Description: Key Points: Cosmogenic 10Be, 14C, and 3He is used to determine erosion rates, erosion styles, and bedrock temperatures in cold regions. 14C/10Be ratios of surface samples reflect the depth at which material was previously eroded, allowing for determination of erosion style. 14C/10Be ratios combined with 10Be‐derived erosion rates improve erosion rate estimates in stochastically eroding environments.
    Description: European Research Council Horizon 2020
    Description: https://doi.org/10.5880/GFZ.3.3.2022.001
    Keywords: ddc:551
    Language: English
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    An Adaptive Hybrid Vertical Equilibrium/Full‐Dimensional Model for Compositional Multiphase Flow (2022)
    Details
    Publication Date: 2022-06-26
    Description: Efficient compositional models are required to simulate underground gas storage in porous formations where, for example, gas quality (such as purity) and loss of gas due to dissolution are of interest. We first extend the concept of vertical equilibrium (VE) to compositional flow, and derive a compositional VE model by vertical integration. Second, we present a hybrid model that couples the efficient compositional VE model to a compositional full‐dimensional model. Subdomains, where the compositional VE model is valid, are identified during simulation based on a VE criterion that compares the vertical profiles of relative permeability at equilibrium to the ones simulated by the full‐dimensional model. We demonstrate the applicability of the hybrid model by simulating hydrogen storage in a radially symmetric, heterogeneous porous aquifer. The hybrid model shows excellent adaptivity over space and time for different permeability values in the heterogeneous region, and compares well to the full‐dimensional model while being computationally efficient, resulting in a runtime of roughly one‐third of the full‐dimensional model. Based on the results, we assume that for larger simulation scales, the efficiency of this new model will increase even more.
    Description: Key Points: A compositional vertical equilibrium model is coupled to its full‐dimensional counterpart. A criterion is developed to adaptively identify and assign regions where the vertical equilibrium model is applicable during simulation. A test case of hydrogen storage in a heterogeneous porous aquifer demonstrates efficiency and accuracy of the hybrid model.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://git.iws.uni-stuttgart.de/dumux-pub/Becker2021b.git
    Keywords: ddc:551.49 ; ddc:550
    Language: English
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    On Timescales and Reversibility of the Ocean's Response to Enhanced Greenland Ice Sheet Melting in Comprehensive Climate Models (2022)
    Details
    Publication Date: 2022-06-26
    Description: Warming of the North Atlantic region in climate history often was associated with massive melting of the Greenland Ice Sheet. To identify the meltwater's impacts and isolate these from internal variability and other global warming factors, we run single‐forcing simulations including small ensembles using three complex climate models differing only in their ocean components. In 200‐year‐long preindustrial climate simulations, we identify robust consequences of abruptly increasing Greenland runoff by 0.05 Sv: sea level rise of 44 ± 10 cm, subpolar North Atlantic surface cooling of 0.7°C, and a moderate AMOC decline of 1.1–2.0 Sv. The latter two emerge in under three decades—and reverse on the same timescale after the perturbation ends in year 100. The ocean translates the step‐change perturbation into a multidecadal‐to‐centennial signature in the deep overturning circulation. In all simulations, internal variability creates notable uncertainty in estimating trends, time of emergence, and duration of the response.
    Description: Plain Language Summary: Enhanced melting of Greenland's glaciers is considered to be a major player in past rapid climate transitions and anticipated to soon impact ocean circulation under current global warming. Global warming triggers complex processes and feedbacks, of which greater amounts of meltwater slowing the large‐scale ocean circulation is only one. To better understand the sensitivity of the real but also the model ocean to just this meltwater, we run idealized experiments with up‐to‐date climate models, which use the same atmosphere and land but different ocean components. We find that sea level rise, cooling of the North Atlantic region, and slowing of the ocean circulation are responses common to all models while regional magnitudes of these responses differ considerably. Once we stop adding freshwater, all three models show that surface temperature and ocean circulation recover as quickly (or slowly) as they changed at the beginning of the experiment. Sea level rise is a lasting impact though.
    Description: Key Points: Sudden increase in Greenland freshwater release is turned into century scale change by deep ocean dynamics. Upper ocean responses to moderately enhanced freshwater release from Greenland reverse on the same timescale once release ceases. Ocean model formulation affects regional expressions but basin‐scale responses are robust, so is the timing on decadal to centennial scales.
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:551.6
    Language: English
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    Attribution of Observed Recent Decrease in Low Clouds Over the Northeastern Pacific to Cloud‐Controlling Factors (2022)
    Details
    Publication Date: 2022-06-26
    Description: Marine low clouds cool the Earth's climate, with their coverage (LCC) being controlled by their environment. Here, an observed significant decrease of LCC in the northeastern Pacific over the past two decades is linked quantitatively to changes in cloud‐controlling factors. In a comparison of different statistical and machine learning methods, a decrease in the inversion strength and near‐surface winds, and an increase in sea surface temperatures (SSTs) are unanimously shown to be the main causes of the LCC decrease. While the decreased inversion strength leads to more entrainment of dry free‐tropospheric air, the increasing SSTs are shown to lead to an increased vertical moisture gradient that enhances evaporation when entrainment takes place. While the LCC trend is likely driven by natural variability, the trend‐attribution framework developed here can be used with any method in future analyses. We find the choice of predictors is more important than the method.
    Description: Plain Language Summary: Marine low clouds efficiently cool the Earth's climate, and their prevalence is controlled by environmental factors. Here, a decrease of the cover of marine low clouds in the northeastern Pacific over the past 20 years is analyzed to attribute the trend to changes in environmental factors known to be important for low clouds. A decrease in the strength of the temperature inversion and an increase in sea surface temperatures (SSTs) are shown to be the main causes of the low‐cloud trend. The decreased inversion strength leads to more mixing in of dry air from above the clouds, leading to cloud evaporation. The increasing SSTs increase the atmospheric moisture levels near the surface more than above the cloud, enhancing evaporation when the mixing takes place. While the trend in low clouds is likely driven by natural variability rather than climate change, the analytical framework developed here can be deployed to attribute causes for trends with any statistical or machine learning method in the future. The analysis shows that the choice of environmental factors used for the analysis has a larger impact on the results than the method.
    Description: Key Points: Significant decrease of low cloud cover in northeastern Pacific in last two decades. Increased vertical moisture gradient, decreased inversion strength, and winds drive low cloud trend. Good agreement between statistical and machine‐learning methods, predictor choice more important.
    Description: Horizon 2020 research and innovation program
    Description: https://doi.org/10.24381/cds.f17050d7
    Description: https://doi.org/10.24381/cds.6860a573
    Description: https://dx.doi.org/10.5067/MODIS/MOD08_M3.061
    Description: http://dx.doi.org/10.5067/MODIS/MYD08_M3.061
    Description: https://doi.org/10.5067/TERRA-AQUA/CERES/EBAF-TOA_L3B004.1
    Description: https://doi.org/10.5281/zenodo.5747221
    Keywords: ddc:551.5
    Language: English
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    Evolution of Rift Systems and Their Fault Networks in Response to Surface Processes (2022)
    Details
    Publication Date: 2022-06-26
    Description: Continental rifting is responsible for the generation of major sedimentary basins, both during rift inception and during the formation of rifted continental margins. Geophysical and field studies revealed that rifts feature complex networks of normal faults but the factors controlling fault network properties and their evolution are still matter of debate. Here, we employ high‐resolution 2D geodynamic models (ASPECT) including two‐way coupling to a surface processes (SP) code (FastScape) to conduct 12 models of major rift types that are exposed to various degrees of erosion and sedimentation. We further present a novel quantitative fault analysis toolbox (Fatbox), which allows us to isolate fault growth patterns, the number of faults, and their length and displacement throughout rift history. Our analysis reveals that rift fault networks may evolve through five major phases: (a) distributed deformation and coalescence, (b) fault system growth, (c) fault system decline and basinward localization, (d) rift migration, and (e) breakup. These phases can be correlated to distinct rifted margin domains. Models of asymmetric rifting suggest rift migration is facilitated through both ductile and brittle deformation within a weak exhumation channel that rotates subhorizontally and remains active at low angles. In sedimentation‐starved settings, this channel satisfies the conditions for serpentinization. We find that SP are not only able to enhance strain localization and to increase fault longevity but that they also reduce the total length of the fault system, prolong rift phases and delay continental breakup.
    Description: Plain Language Summary: Continental rifting is responsible for breaking apart continents and forming new oceans. Rifts generally evolve according to three types: wide rift, symmetric rift, and asymmetric rifts, which also shape the final geometry of the continental rifted margin. Geophysical data shows that the evolution of rifts depends on a multitude of factors including the complex interactions between fault networks that accommodate extension and the processes of erosion and sediment deposition. Here we run 2D computer simulations to investigate fault network evolution during active rifting that include changes to the surface through erosion and sedimentation. By using a new python tool box, we extract the fault network from the simulation and determine individual fault properties like the number of faults, displacement, age, and length through time. We find that regardless of the rift type, rifts evolve according to five phases that can be assessed through the evolution of the fault network properties. Additionally, we find that greater erosion and sedimentation can prolong rift phases and delay the breakup of continents.
    Description: Key Points: We apply a new fault analysis toolbox to coupled numerical models of tectonics and surface processes. Fault network evolution of the major symmetric, asymmetric, narrow, and wide rift types can be described in five distinct phases. Surface processes reduce fault network complexity and delay breakup by enhancing strain localization and increasing fault longevity.
    Description: Helmholtz Young Investigators
    Description: National Science Foundation
    Description: Deutsche Forschungsgemeinschaft (DFG)
    Description: https://doi.org/10.5281/zenodo.5753144
    Keywords: ddc:551.8
    Language: English
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    Investigation of subsurface connectivity and subsurface stormflow in low mountain ranges—Findings from the two research catchments Obere Brachtpe and Bohlmicke (Germany) (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-06-26
    Description: The two small research catchments Obere Brachtpe (2.6 km2; 50.989986, 7.752013) and Bohlmicke (1 km2, 51.079319, 7.892988) are located in the Rhenish Massif, a low mountain range in Germany. Land use in both catchments is dominated by pasture land, spruce stands and mixed forests. Mean annual temperature is 9.1°C, and mean annual total precipitation is 1250 mm, with 15%–20% of the annual precipitation falling as snow. The geology is characterized by sandy silty clay shale from the Lower and Middle Devonian. Loamy Cambisols derived from periglacial slope deposits, complemented by Leptosols and Stagnosols, are the most prominent soils in the catchments. Long‐term hydrological datasets of precipitation, throughfall, discharge, groundwater levels and soil moisture (at different soil depths) in a high temporal and spatial resolution are available for further scientific analysis. Both catchments were monitored within the time period 1999 and 2009, in order to understand how the antecedent soil moisture, stratified soils (periglacial cover beds) and topography (slope form) impacted the subsurface connectivity, and the subsurface stormflow generation ‐ a dominant runoff generation process in humid mountainous catchments. Detailed physically based investigations on runoff processes were carried out, and the obtained results helped to better understand subsurface stormflow generation and subsurface connectivity dynamics. The process knowledge gained, which was presented at several conferences, as well as publications, was the basis for the discussion of open questions within the scientific network ‘Subsurface Stormflow ‐ A well‐recognized, but still challenging process in Catchment Hydrology’ (2016–2021), and the research unit ‘Fast and invisible: conquering subsurface stormflow through an interdisciplinary multisite approach’ (2022–2025), both financed by the German Research Foundation (DFG).
    Description: Long‐term hydrological datasets of precipitation, throughfall, discharge, groundwater levels and soil moisture (at different soil depths) in a high temporal and spatial resolution are available of the two small catchments Obere Brachtpe (2.6 km²) and Bohlmicke (1 km²) (Germany). Both catchments have been monitored in order to understand how the antecedent soil moisture, stratified soils (periglacial cover beds) and topography (slope form) impacted the subsurface connectivity and the subsurface stormflow generation in humid mountainous catchments.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.48
    Language: English
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    Bergordnung für Glashütte 1490 (2022)
    Details
    Publication Date: 2022-07-15
    Description: Bergordnung für die Bergwerke in Glashütte vom 22. Dezember 1490. Erstellt und in Glashütte verlesen wurde sie auf Anordnung von Herzog Georg von Sachsen. In 13 Paragraphen werden die Rechtsgrundlagen beim Betrieb der Bergwerke festgelegt. Als Ort der Verwaltung wird Dippoldiswalde bestimmt.
    Description: source
    Keywords: ddc:622 ; ddc:343.077
    Language: German
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    Multi‐Band Raman Analysis of Radiation Damage in Zircon for Thermochronology: Partial Annealing and Mixed Signals (2022)
    Details
    Publication Date: 2022-06-24
    Description: Four zircon Raman bands were previously calibrated to give consistent estimates of the accumulated self‐irradiation α‐dose in unannealed volcanic samples. Partial annealing of radiation damage produces inconsistent values because of differences in the relative annealing sensitivities. The damage estimates based on the external rotation band (DER) at ∼356 cm−1 and that based on the ν2(SiO4) band (D2) at ∼438 cm−1 are the most and least sensitive to damage annealing. The D2/DER‐ratio thus provides a numerical estimate of the extent of geologic annealing that a zircon sample has experienced. This ratio characterizes the thermal history of a zircon sample but also its state of radiation damage during the course of its geologic history, and thus the manner in which this state influences other thermochronologic methods. Meaningful interpretation of the zircon Raman age requires that the spectra are free of measurement artifacts. The major artifacts result from micrometer‐scale gradients of the damage densities within a zircon grain due to uranium and thorium zoning. The micrometer‐sized sampled volume may span different densities, producing overlapping spectra, causing apparent peak broadening, overestimated damage densities, and zircon Raman ages. The D3/D2‐ratio of the damage densities calculated from the ν3(SiO4) and ν2(SiO4) bands, most and least affected by overlap, is an efficient indicator of a meaningless signal. It reveals overlap in annealed and unannealed samples, because the used bands have similar responses to annealing. Multi‐band Raman maps can be converted to damage‐ratio maps for screening zircon mounts, and selecting spots for thermochronologic investigations.
    Description: Plain Language Summary: Radioactive processes cause damage to the lattice of zircon crystals. This damage can be measured with a Raman instrument. Such measurements are important for methods determining the ages and thermal histories of zircon grains in rocks. Thus, the Raman measurements must be reliable and meaningful. This work proposes tools for detecting effects that hinder the interpretation of zircon Raman data. These effects are mixed signals and loss of damage due to exposure to elevated temperatures in the geologic environment. Zircon Raman spectra have different bands that respond differently to mixed signals and temperature. The ratio of the damage estimates from the least and most temperature‐sensitive bands thus indicates partial annealing. Raman spectra of zoned zircons often straddle areas with different lattice damage. Their overlapping signals cause artificial band broadening, and a damage overestimation. The ratio of the damage estimated from the least and the most affected bands identifies mixed signals and allows to reject unsuitable samples. The damage ratios can also be plotted in maps for damage screening and for selecting optimal spots for measurements.
    Description: Key Points: Annealing and inhomogeneous damage are two main factors hindering radiation‐damage estimation for zircon Raman dating. Comparison of internal and external Raman bandwidths allows to detect partial annealing of radiation damage in zircon. Comparison of internal Raman bandwidths allows to detect artifactual broadening in zoned zircon.
    Description: Studienstiftung des Deutschen Volkes (Studienstiftung) http://dx.doi.org/10.13039/501100004350
    Description: http://dx.doi.org/10.25532/OPARA-155
    Keywords: ddc:549 ; ddc:551.9
    Language: English
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    The Subducting Slab as a Chromatographic Column: Regimes of Sub‐Solidus Mass Transport as a Function of Lithospheric Hydration State, With Special Reference to the Fate of Carbonate (2022)
    Details
    Publication Date: 2022-06-24
    Description: We investigate the chemical budget of subduction zones at sub‐solidus conditions using a thermodynamic‐numerical simulation in which all major rock components are treated as soluble and potentially mobile in aqueous fluids. This new strategy significantly improves the accuracy of predicted fluid‐rock equilibrium compositions in open petrological systems. We show that all slabs release volatiles and nonvolatiles to the mantle wedge, contributing to its refertilization. But some mobile constituents, such as alkali and alumina, may be trapped along layer boundaries or traverse without interaction depending on chemical contrasts between adjacent lithologies. The accumulation of igneous alumina and silica in the limestones of the central‐eastern Pacific slabs drives their decarbonation and is marked by metasomatic garnet growth. Those slabs are also predicted to lose much of their alkalis before sub‐arc depth. Even when they are produced in the altered mafic and ultramafic layers, fluids reach the slab/mantle wedge interface with distinct compositional signatures that are typical of the sedimentary cover. We distinguished supply and transport limited regimes of element subduction by testing the sensitivity of our mass balance to changes in slab hydration state (HS). Transport limited slabs sensitive to HS include notably a hotspot of carbon release to the mantle wedge (e.g., Costa Rica). Finally, we show that the quantitative budgets do depend on the geometry of fluid flows, and on assuming that slabs are mechanically continuous structures, which is questionable. Taken together, these insights will help better constrain the long‐term chemical evolution of the shallow planetary interior, and the thermomechanical behavior of the subduction interface.
    Description: Plain Language Summary: Subduction zones return chemical elements from the surface to the deep Earth. But quantifying this transfer has been challenging. Here, we present a model where all major elements are partly mobile in the fluid phase, enabling us to compile a chemical budget for subduction zones in which only fluids mediate mass transport. We identify transport and supply regimes of element subduction as a function of lithospheric hydration state, rock compositions, and slab temperature. We show that the transport of many rock‐forming elements such as SiO2, CaO, and Al2O3, within and out of the slab, modifies rock composition and contributes to the efficiency of slab decarbonation. Our model of subduction fluid and rock compositions has important implications to understand the role of slab‐derived metasomatic fluid in modifying the composition of the mantle wedge over time, the mechanical properties of deeply subducted rocks, and it will inform future investigations for the high‐pressure petrology of rocky planets in general.
    Description: Key Points. Inter dependence of element transfers in subduction zones. Thermodynamics of intra‐slab metasomatism of major elements. Transport‐ and supply limited regimes of carbonate subduction.
    Description: Alexander von Humboldt‐Stiftung (Humboldt‐Stiftung) http://dx.doi.org/10.13039/100005156
    Description: Branco Weiss Fellowship—Society in Science
    Description: Swiss National Science Foundation
    Description: https://osf.io/y84d2/
    Keywords: ddc:551
    Language: English
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    Sub‐micrometer focusing setup for high‐pressure crystallography at the Extreme Conditions beamline at PETRA III (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2022-06-24
    Description: Scientific tasks aimed at decoding and characterizing complex systems and processes at high pressures set new challenges for modern X‐ray diffraction instrumentation in terms of X‐ray flux, focal spot size and sample positioning. Presented here are new developments at the Extreme Conditions beamline (P02.2, PETRA III, DESY, Germany) that enable considerable improvements in data collection at very high pressures and small scattering volumes. In particular, the focusing of the X‐ray beam to the sub‐micrometer level is described, and control of the aberrations of the focusing compound refractive lenses is made possible with the implementation of a correcting phase plate. This device provides a significant enhancement of the signal‐to‐noise ratio by conditioning the beam shape profile at the focal spot. A new sample alignment system with a small sphere of confusion enables single‐crystal data collection from grains of micrometer to sub‐micrometer dimensions subjected to pressures as high as 200 GPa. The combination of the technical development of the optical path and the sample alignment system contributes to research and gives benefits on various levels, including rapid and accurate diffraction mapping of samples with sub‐micrometer resolution at multimegabar pressures.
    Description: Facing the challenges of X‐ray diffraction from tiny samples subjected to multimegabar pressures, instrumentation developments are presented that enable, among other studies, single‐crystal data collection from micrometer‐ to sub‐micrometer‐sized grains. The developments are based on a sub‐micrometer beam capability employing compound refractive lenses operating with a phase correcting plate and a precise motorization solution.
    Keywords: ddc:548
    Language: English
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    The Vertical Structure and Entrainment of Subglacial Melt Water Plumes (2022)
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    Publication Date: 2022-06-22
    Description: Basal melting of marine‐terminating glaciers, through its impact on the forces that control the flow of the glaciers, is one of the major factors determining sea level rise in a world of global warming. Detailed quantitative understanding of dynamic and thermodynamic processes in melt‐water plumes underneath the ice‐ocean interface is essential for calculating the subglacial melt rate. The aim of this study is therefore to develop a numerical model of high spatial and process resolution to consistently reproduce the transports of heat and salt from the ambient water across the plume into the glacial ice. Based on boundary layer relations for momentum and tracers, stationary analytical solutions for the vertical structure of subglacial non‐rotational plumes are derived, including entrainment at the plume base. These solutions are used to develop and test convergent numerical formulations for the momentum and tracer fluxes across the ice‐ocean interface. After implementation of these formulations into a water‐column model coupled to a second‐moment turbulence closure model, simulations of a transient rotational subglacial plume are performed. The simulated entrainment rate of ambient water entering the plume at its base is compared to existing entrainment parameterizations based on bulk properties of the plume. A sensitivity study with variations of interfacial slope, interfacial roughness and ambient water temperature reveals substantial performance differences between these bulk formulations. An existing entrainment parameterization based on the Froude number and the Ekman number proves to have the highest predictive skill. Recalibration to subglacial plumes using a variable drag coefficient further improves its performance.
    Description: Plain Language Summary: In a world of global warming, the melting of glaciers terminating as floating ice tongues into the oceans of Arctic and Antarctic regions allows those glaciers to flow faster and hence to make a considerable contribution to global mean sea‐level rise. Underneath the ice‐ocean interface, turbulent currents of the order of 10 m thickness (so‐called plumes) develop that transport the melt water from the grounding line where the glacier enters the ocean toward the calving front that marks the seaward end of the glacier. At its base, ambient relatively warm and salty ocean water is mixed into the plumes and is vertically transported toward the ice‐ocean interface, where the melting is increased due to the additional heat supply. Understanding these processes is essential for their incorporation into computer models for the prediction of such melt processes. In this study, an accurate simulation model for the water column is constructed that is able to consistently reproduce these processes. The algorithms developed here are proven to provide reliable results also for models with only a few grid points across the plume and can therefore be implemented into climate models with surface‐following coordinates to more accurately simulate future scenarios of sea level rise.
    Description: Key Points: A vertically resolving model with second‐moment turbulence closure has been constructed for subglacial plumes. Convergent numerical formulations for the ocean‐to‐ice fluxes of momentum, freshwater and heat have been derived from an analytical model. Model results are consistent with bulk parameterizations for the entrainment of ambient water.
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.5281/zenodo.6203838
    Keywords: ddc:550
    Language: English
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    Electrochemical Properties of Peat Particulate Organic Matter on a Global Scale: Relation to Peat Chemistry and Degree of Decomposition (2022)
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    Publication Date: 2022-06-22
    Description: Methane production in peatlands is controlled by the availability of electron acceptors for microbial respiration, including peat dissolved organic matter (DOM) and particulate organic matter (POM). Despite the much larger mass of POM in peat, knowledge on the ranges of its electron transfer capacities—electron accepting capacity (EAC), and electron donating capacity (EDC)—is scarce in comparison to DOM and humic and fulvic acids. Moreover, it is unclear how peat POM chemistry and decomposition relate to its EAC and EDC. To address these knowledge gaps, we compiled peat samples with varying carbon contents from mid to high latitude peatlands and analyzed their EACPOM and EDCPOM, element ratios, decomposition indicators, and relative amounts of molecular structures as derived from mid infrared spectra. Peat EACPOM and EDCPOM are smaller (per gram carbon) than EAC and EDC of DOM and terrestrial and aquatic humic and fulvic acids and are highly variable within and between sites. Both are small in highly decomposed peat, unless it has larger amounts of quinones and phenols. Element ratio‐based models failed to predict EACPOM and EDCPOM, while mid infrared spectra‐based models can predict peat EACPOM to a large extent, but not EDCPOM. We suggest a conceptual model that describes how vegetation chemistry and decomposition control polymeric phenol and quinone contents as drivers of peat EDCPOM and EACPOM. The conceptual model implies that we need mechanistic models or spatially resolved measurements to understand the variability in peat EDCPOM and EACPOM and thus its role in controlling methane formation.
    Description: Plain Language Summary: Peatlands accumulated large amounts of carbon via photosynthesis and slow decomposition of senesced plant material. Microorganisms within the peat form methane. For this reason, peatlands are important global sources of the greenhouse gas methane and therefore can contribute to climate change. In order to produce methane, the microorganisms have to transfer electrons between compounds in respiration processes. Only recently, it has been found that the peat itself can reversibly transfer electrons and that its capacities to reversibly accept electron accepting capacity (EAC) and reversibly donate electron donating capacity (EDC) electrons are large. We investigated which conditions favor large or small EAC and EDC of peat so that we can better explain methane formation. We argue that vegetation and decomposition control the amount of phenols and quinones—molecules in the peat that presumably are responsible for most of the peat's EAC and EDC. The EAC and EDC probably are largest for peat formed from vegetation rich in quinones and phenols, such as shrubs, and smaller for other vegetation types, for example, certain mosses. Intense decomposition may reduce both the EAC and EDC.
    Description: Key Points: Peat particulate organic matter electron accepting and donating capacities per grams of carbon are smaller than for humic and fulvic acids. Both capacities are small in highly decomposed peat, unless it has larger amounts of quinones and phenols. We explain these patterns with parent vegetation chemistry and conditions during decomposition.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: CAS | Youth Innovation Promotion Association (YIPA) http://dx.doi.org/10.13039/501100012492
    Description: https://github.com/henningte/redoxpeat
    Keywords: ddc:551.9
    Language: English
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    Impact of Spreading Rate and Age‐Offset on Oceanic Transform Fault Morphology (2022)
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    Publication Date: 2022-06-22
    Description: Oceanic transform faults (OTFs) are an inherent part of seafloor spreading and plate tectonics, whereas the process controlling their morphology remains enigmatic. Here, we systematically quantify variations in transform morphology and their dependence on spreading rate and age‐offset, based on a compilation of shipborne bathymetric data from 94 OTFs at ultraslow‐ to intermediate‐spreading ridges. In general, the length, width and depth of OTFs scale systematically better with age‐offset rather than spreading rate. This observation supports recent geodynamic models proposing that cross‐transform extension scaling with age‐offset, is a key process of transform dynamics. On the global scale, OTFs with larger age‐offsets tend to have longer, wider, and deeper valleys. However, at small age‐offsets (〈5 Myr), scatters in the depth and width of OTFs increase, indicating that small age‐offset OTFs with weak lithospheric strength are easily affected by secondary tectonic processes.
    Description: Plain Language Summary: In the past 5 decades, studies on oceanic transform faults (OTFs) have revealed significant complexity in their morphology, which calls for detailed quantitative analysis to study the processes controlling the morphology of OTFs. Using the most complete and advanced compilation of bathymetric data from ultraslow‐ to intermediate‐spreading ridges, we parameterized the morphological characteristics of OTFs and extracted length, width and depth for each transform fault from the compiled bathymetric data. Moreover, correlations between these morphological parameters and related tectonic factors (e.g., spreading rate, age‐offset) were investigated in this study. We find that correlations between morphological features and spreading rate are rather weak. Comparison of correlations suggests that age‐offset scales better with the morphological parameters, along with scatters mostly at small age‐offsets, indicating small‐age‐offset OTFs are unstable due to their weak lithospheric strength. Our observation evidences extensional tectonics at OTFs.
    Description: Key Points: We compiled multibeam bathymetric data of 94 oceanic transform faults (OTFs) to quantify their morphological characteristics. Morphology of OTFs is dominated by age‐offset rather than spreading rate. Transform valleys get systematically deeper and wider with increasing age‐offset, implying extensional tectonics at OTFs.
    Description: China Scholarship Council
    Description: http://doi.org/10.5281/zenodo.4774185
    Keywords: ddc:551
    Language: English
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    Rupture Heterogeneity and Directivity Effects in Back‐Projection Analysis (2022)
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    Publication Date: 2022-06-21
    Description: The back projection method is a tremendously powerful technique for investigating the time dependent earthquake source, but its physical interpretation is elusive. We investigate how earthquake rupture heterogeneity and directivity can affect back‐projection results (imaged location and beam power) using synthetic earthquake models. Rather than attempting to model the dynamics of any specific real earthquake, we use idealized kinematic rupture models, with constant or varying rupture velocity, peak slip rate, and fault‐local strike orientation along unilateral or bilateral rupturing faults, and perform back‐projection with the resultant synthetic seismograms. Our experiments show back‐projection can track only heterogeneous rupture processes; homogeneous rupture is not resolved in our synthetic experiments. The amplitude of beam power does not necessarily correlate with the amplitude of any specific rupture parameter (e.g., slip rate or rupture velocity) at the back‐projected location. Rather, it depends on the spatial heterogeneity around the back‐projected rupture front, and is affected by the rupture directivity. A shorter characteristic wavelength of the source heterogeneity or rupture directivity toward the array results in strong beam power in higher frequency. We derive an equation based on Doppler theory to relate the wavelength of heterogeneity with synthetic seismogram frequency. This theoretical relation can explain the frequency‐ and array‐dependent back‐projection results not only in our synthetic experiments but also to analyze the 2019 M7.6 bilaterally rupturing New Ireland earthquake. Our study provides a novel perspective to physically interpret back‐projection results and to retrieve information about earthquake rupture characteristics.
    Description: Plain Language Summary: With the deployment of continental scale seismic arrays, seismologists can quickly locate the high‐frequency seismic radiation sources and track the earthquake rupture propagation using a technique called back‐projection. It is a signal beamforming technique application in seismology, and similar applications can be found in fields such as radar, wireless communication, and radio astronomy. Recent studies have proposed multiple advancements in improving the back‐projection location. However, the physical interpretation of the amplitude of stacked high‐frequency source radiations, which is commonly referred to as beam power, is still challenging since the analysis is not based on a forward model. In this article, we conduct a set of synthetic experiments to investigate the physical significance of back‐projection beam power. We find that beam power is mainly controlled by the spatial heterogeneity wavelength near the rupture front, rupture directivity, and the seismogram frequency. It is in contrast with some previous studies that link the beam power to the maximum slip rate (acceleration) amplitude near the rupture front. Based on the results, we develop a novel theoretical framework that can quantitatively interpret the frequency‐ and array‐dependent back‐projection results not only in our synthetic experiments, but also the 2019 bilateral rupture M7.6 New Ireland earthquake.
    Description: Key Points: We use kinematic forward models to investigate the relation between back‐projection beam location, power and earthquake source properties. Frequency‐dependent back‐projection peak beam power depends on the spatial heterogeneity near the rupture front, and rupture directivity. We develop a novel framework to analyze frequency‐ and array‐dependent back‐projection results, including the 2019 M7.6 New Ireland Event.
    Description: European Union's Horizon 2020 (ChEESE)
    Description: European Research Council (ERC)
    Description: German Research Foundation (DGF)
    Description: KAUST‐CRG
    Description: Leon and Joann V.C. Knopoff
    Description: NSF EAR
    Description: https://doi.org/10.7914/SN/AK
    Description: https://doi.org/10.7914/SN/AT
    Description: https://doi.org/10.7914/SN/AV
    Description: https://doi.org/10.7914/SN/BW
    Description: https://doi.org/10.7914/SN/CC
    Description: https://doi.org/10.7914/SN/CI
    Description: https://doi.org/10.7914/SN/CN
    Description: https://doi.org/10.7914/SN/II
    Description: https://doi.org/10.7914/SN/IU
    Description: https://doi.org/10.7914/SN/TA
    Description: https://doi.org/10.7914/SN/UW
    Keywords: ddc:551.22
    Language: English
    Type: doc-type:article
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