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  • Articles  (1,426)
  • English  (1,425)
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  • 2020-2022  (1,426)
  • 101
    Publication Date: 2020-12-14
    Description: Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While early warning systems are frequently used to predict the magnitude, location and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services or financial loss. Complementing early warning systems with impact forecasts has a two‐fold advantage: it would provide decision makers with richer information to take informed decisions about emergency measures, and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multi‐hazard early warning systems. This review discusses the state‐of‐the‐art in impact forecasting for a wide range of natural hazards. We outline the added value of impact‐based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe.
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  • 102
    Publication Date: 2020-12-14
    Description: This study investigates the usage of HyMAP airborne hyperspectral and Sentinel-2, ASTER and Landsat-8 OLI spaceborne multispectral data for detailed mapping of mineral resources in the Arctic. The EnMAP Geological Mapper (EnGeoMAP) and Iterative Spectral Mixture Analysis (ISMA) approaches are tested for mapping of mafic-ultramafic rocks in areas covered by abundant lichen. Using the Structural Similarity Index Measure (SSIM), the output classification results from airborne data are quantitatively compared to the available geological map and to the HyMAP reference data in case of using spaceborne dataset. Results demonstrate the capability of both airborne and spaceborne data to provide large-scale reconnaissance mapping of geologic materials over vast arctic regions where field access is limited. The distributions of three ultramafic units (dunite, peridotite, pyroxenite) and one mafic unit (gabbro) are mapped based on analyzing specific visible and near-infrared and short-wave-infrared spectral features. The extent of peridotite and dunite units mapped using both approaches is consistent with geological map, whereas pyroxenite abundance maps show different patterns in their distribution as compared to the geological map. The results suggest that EnGeoMAP method has a better performance than ISMA method for mapping the dunite unit, whilst ISMA performs better for mapping peridotite and pyroxenite rocks.
    Language: English
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  • 103
    Publication Date: 2020-12-14
    Description: In risk assessment, the exposure component describes the elements exposed to the natural hazards and susceptible to damage or loss, while the vulnerability component defines the likelihood to incur damage or loss conditional on a given level of hazard intensity. In this article, we propose a novel adaptive approach to exposure modeling which exploits Dirichlet-Multinomial Bayesian updating to implement the incremental assimilation of sparse in situ survey data into probabilistic models described by compositions (proportions). This methodology is complemented by the introduction of a custom spatial aggregation support based on variable-resolution Central Voronoidal Tessellations. The proposed methodology allows for a more consistent integration of empirical observations, typically from engineering surveys, into large-scale models that can also efficiently exploit expert-elicited knowledge. The resulting models are described in a probabilistic framework, and as such allow for a more thorough analysis of the underlying uncertainty. The proposed approach is applied and discussed in five countries in Central Asia.
    Language: English
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  • 104
    Publication Date: 2020-12-14
    Description: Knowledge of the in‐situ stress state of the Earth´s crust plays a key role in understanding geological processes including plate tectonics, earthquakes, slope failure and igneous emplacement. In this paper, we determine the in‐situ stress orientation from the PTA2 borehole on the Island of Hawai´i, drilled into a lava flow dominated sequence between Mauna Kea and Mauna Loa. High‐resolution acoustic images were collected from the open hole interval 886 m to 1567 m. Based on identification of 371 borehole breakouts for a total length of 310 m, the mean orientation of the minimum horizontal principal stress is N106° and remains constant across different volcanic rock fabrics. Changes in borehole breakout shape are linked to the different strength of volcanic facies and intra‐facies. The orientation of the present‐day stress field at Mauna Kea deviates from the plate forces and regional tectonic stress field. We interpret the compressive stress regime at the PTA2 site as resulting from the competing gravitational fields of the large topographic highs of Mauna Kea and Mauna Loa. Our study reveals that the mass accumulation associated with shield volcano growth imparts significant local variations to the sub‐surface stress state on volcanic islands consisting of overlapping shield volcanoes. The results have significant implications for stress accumulation leading to brittle failure and flank collapse, along with potentially influencing magma accumulation and ascent pathways during volcanic island evolution. This study provides the first insights into the orientation of the present‐day stress field between the major island forming shield volcanoes of Hawai’i.
    Language: English
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  • 105
    Publication Date: 2020-12-14
    Description: Wind turbines produce mechanical energy that can propagate to the ground and disturb sensitive measurements such as seismic recordings. The aim of the large-scale experiment Seismic Monitoring And Research of wind Turbine Induced Emissions (SMARTIE1) at a single wind turbine in Pfinztal (SW Germany) is to understand how wind turbines emit seismic signals under different operating conditions and how these seismic signals propagate through the local subsurface. The main objectives of SMARTIE1 are the investigation of wind turbine induced seismic signals, the characteristics of their propagation behaviour, as well as the radiation pattern of a single wind turbine as defined using particle motions. Moreover, we quantify the emission of the wind turbine induced seismic signals with respect to the wind speed. The combination of the wind turbine’s emission into the subsurface and the attenuation behaviour of the seismic signals (ground motion velocity) can be used to estimate protection radii around seismic stations to ensure the recording of seismic signals without noticeable influences of the wind turbines. In this study, we detect several discrete wind turbine induced frequency peaks ranging from 1 to 10 Hz. We identify a radiation pattern of the wind turbine, which could give further insights into the interaction between the movement of the wind turbine’s nacelle and the generation of the wind turbine induced seismic signals. Using profile measurements with a maximum distance of almost 3 km each, we fit a power-law decay for power spectral density proportional to 1/r b. The attenuation factor, b, ranges from 0.7 to 1.3 for lower frequencies between 1 and 4 Hz, and increases to b = 2.3 for the higher frequency peak around 5.25 Hz. Finally, we present an example of estimation of a protection radius around the seismic station of the Collm Observatorium that is part of the German Regional Seismic Network. The example protection radius around Collm Observatorium regarding this single wind turbine is reached at a minimum distance of 3.7 km.
    Language: English
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  • 106
    Publication Date: 2020-12-14
    Description: In the framework of the Deep Electromagnetic Soundings for Mineral Exploration project, we conducted ground‐based long‐offset transient‐electromagnetic measurements in a former mining area in eastern Thuringia, Germany. The large‐scale survey resulted in an extensive dataset acquired with multiple high‐power transmitters and a high number of electric and magnetic field receivers. The recorded data exhibit a high data quality over several decades of time and orders of magnitude. Although the obtained subsurface models indicate a strong multi‐dimensional subsurface with variations in resistivity over three orders of magnitude, the electrical field step‐on transients are well fitted using a conventional one‐dimensional inversion. Due to superimposed induced polarization effects, the transient step‐off data are not interpretable with conventional electromagnetic inversion. For further interpretation in one and two dimensions, a new approach to evaluate the long‐offset transient‐electromagnetic data in frequency domain is realized. We present a detailed workflow for data processing in both domains and give an overview of technical obstructions that can occur in one domain or the other. The derived one‐dimensional inversion models of frequency‐domain data show strong multi‐dimensional effects and are well comparable with the conventional time domain inversion results. To adequately interpret the data, a 2.5D frequency‐domain inversion using the open source algorithm MARE2DEM (Modeling with Adaptively Refined Elements for 2‐D EM) is carried out. The inversion leads to a consistent subsurface model with shallow and deep conductive structures, which are confirmed by geology and additional geophysical surveys.
    Language: English
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  • 107
    Publication Date: 2020-12-14
    Description: Geothermal reservoir production and associated induced seismicity may experience pronounced attention in the near future, given the ambitious plans for reducing greenhouse gas emissions toward a carbon-neutral economy and society. At some geothermal sites, the occurrence of hazard- and risk-prone induced earthquakes caused by or associated with reservoir stimulation has resulted in project shutdown (e.g., Pohang, South Korea, and Basel Deep Heat Mining, Switzerland). At other geothermal sites, the maximum event magnitudes were successfully maintained below a threshold defined by local authorities (e.g., Helsinki St1 Deep Heat project in Helsinki, Finland). In this study, we review some of our results from seismological and geomechanical reservoir characterization at The Geysers geothermal reservoir in California, USA, the largest producing geothermal field worldwide. We relate our findings to other geothermal sites to better understand the variability of reservoir behavior. In particular, we obtain a constant and relatively low seismic injection efficiency at The Geysers, which is interpreted to be related to the large energy dissipation through thermal processes and additional dissipation through aseismic slip, the latter now being considered to play a fundamental role in earthquake nucleation. We discuss some characteristics of the seismicity from The Geysers that suggest stable reservoir seismic injection efficiency and possibly low potential to rupture into large induced earthquakes, reducing the associated seismic hazard.
    Language: English
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  • 108
    Publication Date: 2020-12-14
    Description: Different Earth orientation parameter (EOP) time series are publicly available that typically arise from the combination of individual space geodetic technique solutions. The applied processing strategies and choices lead to systematically differing signal and noise characteristics particularly at the shortest periods between 2 and 8 days. We investigate the consequences of typical choices by introducing new experimental EOP solutions obtained from combinations at either normal equation level processed by Deutsches Geodätisches Forschungsinstitut at the Technical University of Munich (DGFI‐TUM) and Federal Agency for Cartography and Geodesy (BKG), or observation level processed by European Space Agency (ESA). All those experiments contribute to an effort initiated by ESA to develop an independent capacity for routine EOP processing and prediction in Europe. Results are benchmarked against geophysical model‐based effective angular momentum functions processed by Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences (ESMGFZ). We find, that a multitechnique combination at normal equation level that explicitly aligns a priori station coordinates to the ITRF2014 frequently outperforms the current International Earth Rotation and Reference Systems Service (IERS) standard solution 14C04. A multi‐Global Navigation Satellite System (GNSS)‐only solution already provides very competitive accuracies for the equatorial components. Quite similar results are also obtained from a short combination at observation level experiment using multi‐GNSS solutions and SLR from Sentinel‐3A and Sentinel‐3B to realize space links. For ΔUT1, however, very long baseline interferometry (VLBI) information is known to be critically important so that experiments combining only GNSS and possibly SLR at observation level perform worse than combinations of all techniques at normal equation level. The low noise floor and smooth spectra obtained from the multi‐GNSS solution nevertheless illustrates the potential of this most rigorous combination approach so that further efforts to include in particular VLBI are strongly recommended.
    Language: English
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  • 109
    Publication Date: 2020-12-14
    Description: Carbonates are the major hosts of carbon on Earth’s surface and their fate during subduction needs to be known to understand the deep carbon cycle. Magnesite (MgCO3) is thought to be an important phase participating in deep Earth processes, but its phase stability is still a matter of debate for the conditions prevalent in the lowest part of the mantle and at the core mantle boundary. Here, we have studied the phase relations and stabilities of MgCO3 at these P,T conditions, using Raman spectroscopy at high pressures (∼148GPa) and after heating to high temperatures (∼3600 K) in laser-heated diamond anvil cell experiments. The experimental Raman experiments were supplemented by x-ray powder diffraction data, obtained at a pressure of 110 GPa. Density-functional-theory-based model calculations were used to compute Raman spectra for several MgCO3 high-pressure polymorphs, thus allowing an unambiguous assignment of Raman modes. By combining the experimental observations with the density-functional-theory results, we constrain the phase stability field of MgCO3 with respect to the high-pressure polymorph, MgCO3-II. We further confirm that Fe-free MgCO3-II is a tetracarbonate with monoclinic symmetry (space group C2/m), which is stable over the entire P, T range of the Earth’s lowermost mantle geotherm.
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  • 110
    Publication Date: 2020-12-14
    Description: The magnetic equator in the Brazilian region has moved over 1100 km northwards since 1957, passing the geomagnetic observatory Tatuoca (TTB), in northern Brazil, around 2013. We recovered and processed TTB hourly mean values of the geomagnetic field horizontal (H) component from 1957 until 2019, allowing the investigation of long‐term changes in the daily variation due to the influence of secular variation, solar activity, season and lunar phase. The H day‐to‐day variability and the occurrence of the counter electrojet at TTB were also investigated. Until the 1990s, ionospheric solar quiet currents dominated the quiet‐time daily variation at TTB. After 2000, the magnitude of the daily variation became appreciably greater due to the equatorial electrojet (EEJ) contribution. The H seasonal and day‐to‐day variability increased as the magnetic equator approached, but their amplitudes normalized to the average daily variation remained at similar levels. Meanwhile, the amplitude of the lunar variation, normalized in the same way, increased from 5% to 12%. Within the EEJ region, the occurrence rate of the morning counter electrojet (MCEJ) increased with proximity to the magnetic equator, while the afternoon counter electrojet (ACEJ) did not. EEJ currents derived from CHAMP and Swarm satellite data revealed that the MCEJ rate varies with magnetic latitude within the EEJ region while the ACEJ rate is largely constant. Simulations with the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model based on different geomagnetic main field configurations suggest that long‐term changes in the geomagnetic daily variation at TTB can be attributed to the main field secular variation.
    Language: English
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  • 111
    Publication Date: 2020-12-14
    Description: Synthetic portlandite single crystals were used to measure thermal diffusivity and elastic constants. The full tensor of elastic constants cijkl is derived by Brillouin spectroscopy at ambient conditions. The resultant aggregate bulk and shear moduli are KS, VRH=32.2(3) GPa and GVRH=21.2(2) GPa, respectively. The thermal diffusivity D was measured from −100∘C to 700∘C parallel [001] and perpendicular [100] to the crystallographic c-axis using laser flash method. The dehydration of the crystals influences the thermal diffusivity determination depending on sample size, orientation and heating rate. Thermal diffusivity and the derived thermal conductivity show a pronounced anisotropy with a maximum perpendicular to the c-axis, i.e. in the plane of the [CaO6] octahedral layers. In the same direction the highest sound velocities (vP and vmean) and longest mean free path length of phonons are determined. The thermal diffusivity as well as the derived thermal conductivity show a distinct temperature dependence.
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  • 112
    Publication Date: 2020-12-14
    Description: The tectonic activity and potential for linkage of adjacent active faults are crucial for seismic assessment. As the two largest faults that bound the Weihe Graben (central China), the Qinling Northern Piedmont Fault (QNF, ~200 km) and the Huashan Piedmont Fault (HPF, ~150 km) are mainly responsible for seismic risk in this densely-populated area, where the 1556 M 8.5 Huaxian earthquake occurred with 830,000 fatalities. However, their tectonic activity and the degree of interaction remain poorly constrained, hampering an adequate seismic risk assessment of the Weihe Graben. Here, we integrate 23 new 10Be-derived catchment-averaged denudation rates of ~0.06–0.32 mm/yr with topographic metrics to evaluate the seismic risk. The results demonstrate that the landscape of the Qinling and Huashan Mountains is in transient state in response to the tectonic perturbations of the QNF and the HPF, with tectonic knickpoints formed along main streams and tributaries, and widespread unstable drainage divides. These two faults have comparable tectonic activity, and are potentially capable of generating earthquakes with the maximum magnitude of Mw ~7.7–7.9. Moreover, they have likely started linking, posing a greater seismic risk than previously estimated.
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  • 113
    Publication Date: 2020-12-14
    Description: Methane emissions from natural wetlands tend to increase with temperature and therefore may lead to a positive feedback under future climate change. However, their temperature response includes confounding factors and appears to differ on different time scales. Observed methane emissions depend strongly on temperature on a seasonal basis, but if the annual mean emissions are compared between sites, there is only a small temperature effect. We hypothesize that microbial dynamics are a major driver of the seasonal cycle and that they can explain this apparent discrepancy. We introduce a relatively simple model of methanogenic growth and dormancy into a wetland methane scheme that is used in an Earth system model. We show that this addition is sufficient to reproduce the observed seasonal dynamics of methane emissions in fully saturated wetland sites, at the same time as reproducing the annual mean emissions. We find that a more complex scheme used in recent Earth system models does not add predictive power. The sites used span a range of climatic conditions, with the majority in high latitudes. The difference in apparent temperature sensitivity seasonally versus spatially cannot be recreated by the non‐microbial schemes tested. We therefore conclude that microbial dynamics are a strong candidate to be driving the seasonal cycle of wetland methane emissions. We quantify longer‐term temperature sensitivity using this scheme and show that it gives approximately a 12% increase in emissions per degree of warming globally. This is in addition to any hydrological changes, which could also impact future methane emissions.
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  • 114
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    In:  Earth and Space Science
    Publication Date: 2020-12-14
    Description: Multispacecraft missions such as Cluster, Themis, Swarm, and MMS contribute to the exploration of geospace with their capability to produce gradient and curl estimates from sets of spatially distributed in situ measurements. This paper combines all existing estimators of the reciprocal vector family for spatial derivatives and their errors. The resulting framework proves to be robust and adaptive in the sense that it works reliably for arrays with arbitrary numbers of spacecraft and possibly degenerate geometries. The analysis procedure is illustrated using synthetic data as well as magnetic measurements from the Cluster and Swarm missions. An implementation of the core algorithm in Python is shown to be compact and computationally efficient so that it can be easily integrated in the various free and open source packages for the Space Physics and Heliophysics community.
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  • 115
    Publication Date: 2020-12-14
    Description: Space weather driven atmospheric density variations affect low Earth orbit (LEO) satellites during all phases of their operational lifetime. Rocket launches, re-entry events and space debris are also similarly affected. A better understanding of space weather processes and their impact on atmospheric density is thus critical for satellite operations as well as for safety issues. The Horizon 2020 project Space Weather Atmosphere Model and Indices (SWAMI) project, which started in January 2018, aims to enhance this understanding by: - Developing improved neutral atmosphere and thermosphere models, and combining these models to produce a new whole atmosphere model. - Developing new geomagnetic activity indices with higher time cadence to enable better representation of thermospheric variability in the models, and improving the forecast of these indices. The project stands out by providing an integrated approach to the satellite neutral environment, in which the main space weather drivers are addressed together with model improvement. The outcomes of SWAMI will provide a pathway to improved space weather services as the project will not only address the science issues, but also the transition of models into operational services. The project aims to develop a unique new whole atmosphere model, by extending and blending the Unified Model (UM), which is the Met Office weather and climate model, and the Drag Temperature Model (DTM), which is a semi-empirical model which covers the 120–1500 km altitude range. A user-focused operational tool for satellite applications shall be developed based on this. In addition, improved geomagnetic indices shall be developed and shall be used in the UM and DTM for enhanced nowcast and forecast capability. In this paper, we report on progress with SWAMI to date. The UM has been extended from its original upper boundary of 85 km to run stably and accurately with a 135 km lid. Developments to the UM radiation scheme to enable accurate performance in the mesosphere and lower thermosphere are described. These include addition of non-local thermodynamic equilibrium effects and extension to include the far ultraviolet and extreme ultraviolet. DTM has been re-developed using a more accurate neutral density observation database than has been used in the past. In addition, we describe an algorithm to develop a new version of DTM driven by geomagnetic indices with a 60 minute cadence (denoted Hp60) rather than 3-hourly Kp indices (and corresponding ap indices). The development of the Hp60 index, and the Hp30 and Hp90 indices, which are similar to Hp60 but with 30 minute and 90 minute cadences, respectively, is described, as is the development and testing of neural network and other machine learning methods applied to the forecast of geomagnetic indices.
    Language: English
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  • 116
    Publication Date: 2020-12-14
    Description: The W. Alps high pressure ophiolitic terranes (Monviso and Rocciavre areas) are a natural laboratory to study processes such as nappe-stacking and crustal exhumation in the deep regions of subduction margins. We sampled each of the main shear zones, representing thrust contacts later reactivated as detachments, for petrological and Rb-Sr multi-mineral geochronological analyses. Three generations of white mica are commonly found in mylonitized metasediments with crystal cores formed during the high pressure event, a broad rim formed during decompression in the epidote blueschist facies and texturally late muscovite flakes locally lining the main foliation. Semi-brittle discrete shear zones commonly crosscut previous structures witnessing deformation at temperatures lower than 300°C during exhumation. In spite of this apparent structural heterogeneity, homogeneous deformation ages mostly ranging between 38 and 35 Ma were obtained for all the shear zones bounding these major ophiolitic bodies. Pseudosection modeling confirms that the bulk of the shearing occurred in the epidote blueschist facies around 400–450°C and 1.0–1.5 GPa. These findings suggest that the shear zones between high pressure ophiolitic nappes were being actively mylonitized during exhumation in the lower epidote blueschist facies (25–40 km depth) between 38 and 35 Ma while some of the units forming the internal crystalline massifs (e.g. the Dora Maira Ultra High-Pressure unit) were still buried at more than 100 km depth (3–4 GPa and 36-34 Ma, according to most recent peak burial estimates). The growth of a crustal-scale duplex in the W. Alps is seen here as a consequence of basal accretion events that followed the exhumation of eclogitized coherent crustal slices in a serpentinized subduction channel. We conclude that in the study area (i) the buoyancy-driven exhumation of subducted continental crust has not been the only and decisive trigger for the exhumation of eclogitized oceanic lithosphere and (ii) continental subduction imprint on crustal wedge dynamics may have not been as instrumental as previously thought.
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  • 117
    Publication Date: 2020-12-14
    Description: As an integral part of the Eastern Cordillera, the fault-bounded Malcante mountain range (up to 5100 m) in the NW Argentine Andes (ca. 25°S) is located in the transition between the arid Puna Plateau to the west and the humid broken foreland to the east. At this latitude, the topographic gradient of the eastern Andean margin forms an efficient orographic barrier that causes pronounced east–west rainfall and surface-process gradients. In this setting, the Malcante Range is an important, yet poorly studied structural high formed during the Cenozoic topographic growth of the Central Andes. In this study, we combine (a) detailed field observations, (b) a two-dimensional structural reconstruction, (c) apatite fission track and (U–Th-Sm)/He thermochronology of bedrock samples from a vertical transect across the western flank of the Malcante Range, and (d) inverse thermal modelling using QTQt software with the aim of deciphering the exhumation history of this mountain range. Field data indicate the presence of an angular unconformity between Cenozoic foreland deposits and older sedimentary strata, suggesting an initial episode of deformation during the middle-late Eocene, while our thermal model constrains the onset of exhumation at ~10 Ma. We suggest that exhumation was related to the unroofing of the easily erodible sedimentary cover, which prevented significant initial surface uplift. This may have changed as more resilient bedrock was exposed at ~5 Ma according to the thermal model, promoting rapid rock uplift. In combination with published data, our thermochronology allows us to speculate on the existence of a zone of deformation concentrated in the area of the present-day Pasha (24.5°S), Malcante (25°S), and Agua de Castilla (25.4°S) mountain ranges by ca. 10 Ma.
    Description: Thermochronology, Apatite fission track, Apatite (U–Th)/He, Mountain building, Eastern cordillera, NW Argentina
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  • 118
    Publication Date: 2020-12-14
    Description: The relationships between volcanic activity and tectonics at the southernmost termination of the Main Ethiopian Rift (MER), East Africa, still represent a debated problem in the MER evolution. New constraints on the timing, evolution and characteristics of the poorly documented volcanic activity of the Dilo and Mega volcanic fields (VF), near the Kenya-Ethiopia border are here presented and discussed. The new data delineate the occurrence of two distinct groups of volcanic rocks: 1) Pliocene subalkaline basalts, observed only in the Dilo VF, forming a lava basement faulted during a significant rifting phase; 2) Quaternary alkaline basalts, occurring in the two volcanic fields as pyroclastic products and lava flows issued from monogenetic edifices and covering the rift-related faults. 40Ar/39Ar dating constrains the emplacement time of the large basal lava plateau to ~3.7 Ma, whereas the youngest volcanic activity characterising the two areas dates back to 134 ka (Dilo VF) to as recent as the Holocene (Mega VF). Volcanic activity developed along tectonic lineaments independent from those of the rift. No direct relations are observed between the Pliocene, roughly N-S-trending major boundary faults of the Ririba rift and the NE-SW-oriented structural trend characteristic of the Quaternary volcanic activity. We speculate that this change in structural trend may be the expression of (1) inherited crustal structures affecting the distribution of the recent volcanic vents, and (2) a local stress field controlled by differences in crustal thickness, following a major episode of reorganization of extensional structures in the region due to rift propagation and abandonment.
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  • 119
    facet.materialart.
    Unknown
    In:  GFF
    Publication Date: 2020-12-14
    Description: One of Sweden’s most successful geologists, Professor Ove Stephansson, passed away on February, 19 2020. During his professional life he published more than 200 articles, conference papers and books.
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  • 120
    Publication Date: 2020-12-14
    Description: Knowledge of the internal state of rock is key to anticipate its rheological response and susceptibility to external factors. Time‐dependent failure in rock is controlled by internal state changes, like damage accumulation or strength degradation. But assessing internal states and changes thereof, non‐destructively and independent of external forcing is not straight forward. Residual strains, measured with neutron diffraction techniques are used as a proxy for the internal state in material sciences. We investigated its potential for progressive rock failure by measuring residual strain states of an untested and three mechanically and chemo‐mechanically pretested Carrara marble samples. We collected neutron diffraction data for three crystal lattice planes {10̅14}, {0006}, and {11̅20}. Measurements showed an initial overall contractional spatially homogeneous residual unit cell volume strain state of about ‐400μstrain, though magnitudes were strongly partitioned among measured crystal lattice planes. However, they are equal within the spatial orientations of the intact sample. For the pretested samples, the induction and relaxation of strains varied spatially with the pretesting stress field and environmental conditions. The vertical extent of superposition of the initial residual strain state was greatest in wet samples, the magnitude of induced extensional strain highest in the dry sample. This indicates chemo‐mechanically enhanced subcritical crack growth with concomitant residual strain relaxation as well as the mitigation of extensional strain built up by the presence of water during pretesting. Our experiments show, that residual strain has a significant potential to provide insights into past and actual internal states to anticipate progressive rock failure.
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  • 121
    Publication Date: 2020-12-14
    Description: We present a new set of global and local sea‐level projections at example tide gauge locations under the RCP2.6, RCP4.5 and RCP8.5 emissions scenarios. Compared to the CMIP5‐based sea‐level projections presented in IPCC AR5, we introduce a number of methodological innovations, including: (i) more comprehensive treatment of uncertainties; (ii) direct traceability between global and local projections; (iii) exploratory extended projections to 2300 based on emulation of individual CMIP5 models. Combining the projections with observed tide gauge records, we explore the contribution to total variance that arises from sea‐level variability, different emissions scenarios and model uncertainty. For the period out to 2300 we further breakdown the model uncertainty by sea‐level component and consider the dependence on geographic location, time horizon and emissions scenario. Our analysis highlights the importance of variability for sea‐level change in the coming decades and the potential value of annual‐to‐decadal predictions of local sea‐level change. Projections to 2300 show a substantial degree of committed sea‐level rise under all emissions scenarios considered and highlights the reduced future risk associated with RCP2.6 and RCP4.5 compared to RCP8.5. Tide gauge locations can show large (〉 50%) departures from the global average, in some cases even reversing the sign of the change. While uncertainty in projections of the future Antarctic ice dynamic response tends to dominate post‐2100, we see a substantial differences in the breakdown of model variance as a function of location, timescale and emissions scenario.
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  • 122
    Publication Date: 2020-12-14
    Description: Shrub encroachment has far‐reaching ecological and economic consequences in many ecosystems worldwide. Yet, compositional changes associated with shrub encroachment are often overlooked despite having important effects on ecosystem functioning. We document the compositional change and potential drivers for a northern Namibian Combretum woodland transitioning into a Terminalia shrubland. We use a multiproxy record (pollen, sedimentary ancient DNA, biomarkers, compound‐specific carbon (δ13C) and deuterium (δD) isotopes, bulk carbon isotopes (δ13Corg), grain size, geochemical properties) from Lake Otjikoto at high taxonomical and temporal resolution. We provide evidence that state changes in semiarid environments may occur on a scale of one century and that transitions between stable states can span around 80 years and are characterized by a unique vegetation composition. We demonstrate that the current grass/woody ratio is exceptional for the last 170 years, as supported by n‐alkane distributions and the δ13C and δ13Corg records. Comparing vegetation records to environmental proxy data and census data, we infer a complex network of global and local drivers of vegetation change. While our δD record suggests physiological adaptations of woody species to higher atmospheric pCO2 concentration and drought, our vegetation records reflect the impact of broad‐scale logging for the mining industry, and the macrocharcoal record suggests a decrease in fire activity associated with the intensification of farming. Impact of selective grazing is reflected by changes in abundance and taxonomical composition of grasses and by an increase of nonpalatable and trampling‐resistant taxa. In addition, grain‐size and spore records suggest changes in the erodibility of soils because of reduced grass cover. Synthesis. We conclude that transitions to an encroached savanna state are supported by gradual environmental changes induced by management strategies, which affected the resilience of savanna ecosystems. In addition, feedback mechanisms that reflect the interplay between management legacies and climate change maintain the encroached state.
    Language: English
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  • 123
    Publication Date: 2020-12-14
    Description: This paper presents the results of multiproxy research (pollen, charcoal, plant macrofossil and testate amoebae) on the biogenic deposits core from Gorodetsky Moch, an ombrotrophic peatland in western Russia (Western Dvina Lakeland). We reconstructed the impact of disturbance on peatland development in the last 300 years by using chronology of the records based on 14C and 210Pb data set. The multiproxy reconstruction was compared with changes in the land cover using historical maps and Corona images, which provides a unique spatial analysis of past ecological and land-use changes. We aimed to determine the effect of local disturbances (drainage) and land-use changes (landscape openness) on the development of the peatland during the last 300 years. Our study suggests that human activity had a crucial impact on the development of the peatland in the last centuries. The analysis of testate amoebae and plant macrofossils revealed a clear disturbed layer in the second half of the 20th century CE. Most probably, the drainage of the peatland triggered changes in the community of testate amoebae and plants, thereby causing a functional shift in Sphagnum peatland ecosystem. The hydrological stress and vegetation composition shift led to the collapse of mixotrophic testate amoebae. However, the peatland showed strong resilience and recovered toward the end of the 20th century CE and the beginning of the 21st century CE, despite the lower water table. Our study shows an example of the peatland ecosystem that experienced a considerable stress but finally sustained the former function.
    Language: English
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  • 124
    Publication Date: 2020-12-14
    Description: Primary productivity of forest ecosystems depends on the availability of plant‐essential mineral nutrients. Because nutrient demand of trees often exceeds nutrient supply from rock, tree nutrition is sustained by efficient re‐utilization of organic‐bound nutrients. These nutrients are continuously returned from trees to the forest floor in litterfall. However, over millennia nutrient limitation may develop in landscapes from which nutrients are permanently lost by drainage and erosion. Such a deficit is prevented if advection of unweathered bedrock towards the surface as driven by erosion continuously supplies fresh nutrients. Yet, the mechanisms and the depth range over which this deep nutrient resource is accessed are poorly known. We show that in two montane temperate forest ecosystems in the Black Forest and Bavarian Forest the geogenic source of nutrients was found within a depth zone of several meters. This deep zone contains a large pool of biologically available nutrients. We applied isotope ratios as proxies for nutrient uptake depth, and we tracked the regolith depth at which the isotope ratios of 87Sr/86Sr and 10Be(meteoric)/9Be match the respective values in plant tissue. We mapped the depth distribution of the biologically available calcium‐bound form of the most plant‐essential mineral nutrient phosphorus and found that the depth of phosphorus availability is as deep or even deeper as the range defined by the isotope ratios. We conclude that nutrient supply from a regolith depth of several meters is critical for forest ecosystem function in landscapes of moderate hillslopes and rainfall that are affected by permanent nutrient loss.
    Language: English
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  • 125
    Publication Date: 2020-12-14
    Description: A reliable evaluation of four Scintrex CG-6 gravimeters was done with respect to the stability of the calibration, measurement uncertainty, repeatability, and daily drift behaviour. An uncertainty on the 10 nm/s2 level for adjusted g-results is striven for. Measurements were performed on the Vertical Gravimeter Calibration Line Hannover (VGCH, 192 μm/s2 range, 20-storey building, 10 μm/s2 interval, 2 · 10−4 expanded uncertainty of the scale). The achieved standard deviations of the adjusted calibration factors are in the order of 2 to 6 · 10−5, and the maximum variations between two calibration results for a single instrument varied between 2 to 7 · 10−4. Therefore, the stability of the scale factor (calibration) of a CG-6 instrument has to be controlled by the user before and after the microgravimetric survey. The transportation drift over some hours or a working day shows partly short-term variations with an impact of up to 100 nm/s2 which can only be identified and controlled by sufficient repeated observations on same points. The manufacturer Scintrex Ltd. solved the problematic nature of an instrumental air pressure effect but a test especially for older CG gravimeters is still recommended. Overall, the CG-6 gravimeters meet fully the expectations.
    Description: Eine wirklichkeitsgetreue Evaluierung von vier Scintrex-CG6-Gravimetern wurde vorgenommen, um Aus­sagen zur Stabilität ihrer Kalibrierung, Messunsicherheit, Wiederholbarkeit und des Driftverhaltens treffen zu können. Dabei wird für ausgeglichene Schwerewerte eine Unsicherheit in der Größenordnung von 10 nm/­s 2 angestrebt. Die Messungen wurden in der Vertikalen Gravimeter-Kalibrierlinie Hannover durchgeführt. Die 20 Punkte decken insgesamt einen Schwerebereich von 192 μm/s 2 ab und haben einen Nachbarschaftsabstand von jeweils 10 μm/s 2 . Die Maßstabsgenauigkeit wird relativ mit 2 · 10 −4 angenommen. Bei den CG-6-Untersuchungen wurden für die Kalibrierfaktoren Standardabweichungen von 2 bis 6 · 10 −5 erhalten. Allerdings unterscheiden sich die einzelnen zeitlich auseinanderliegenden Kalibrierergebnisse mit maximalen Diskrepanzen zwischen 2 bis 7 · 10 −4 . Deshalb sollte die zeitliche Stabilität der Maßstabsfaktoren (Kalibrierung) der CG-6-Gravimeter durch die Nutzer jeweils vor und nach den mikrogravimetrischen Vermessungen kontrolliert werden. Die Transportdriften über einige Stunden oder einem Arbeitstag zeigen z. T. kurzperiodische Variationen mit Diskrepanzen von bis zu 100 nm/s 2. Bei Vermessungen mit nur einem Instrument können solche Driftverläufe nur durch wiederholtes Messen auf den einzelnen Punkten erkannt werden. Der Hersteller Scintrex Ltd. hat die Problematik eines instrumentellen Luftdruckeffekts bei seinen Instrumenten gelöst. Allerdings wird eine Überprüfung besonders bei älteren CG-Gravimetern seitens der Autoren empfohlen. Im Ganzen gesehen erfüllen die neuen CG-6-Gravimeter die Erwartungen.
    Language: English
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  • 126
    Publication Date: 2020-12-14
    Description: The exchange of hydrate-bond CH4 with CO2 is one possible method for the production of CH4 from hydrate-bearing sediment which was investigated on different scales in the SUGAR project. Tubular polydimethylsiloxane (PDMS) membranes were utilized to monitor the spatial and temporal gas distribution in a large-scale experimental simulation on CO2–CH4 gas hydrate exchange. The suitability of PDMS membranes for the measurement of gaseous and dissolved CO2 and CH4 concentrations in pure and mixed gas systems was evaluated in lab-scale experiments. The results reveal a strong interacting mutual influence of CO2 and CH4 in CO2–CH4 mixed feed composition and in the presence of water. The competitive absorption between CO2 and H2O as well as membrane plasticization, which increases CH4 permeability and reduces CO2 permeability, makes a direct correlation of mixed systems to pure systems and a quantification of the gas concentration in the feed reservoir impossible. The successful run of five tubular PDMS membranes, employed in a large test reservoir during an experimental simulation of CO2-driven CH4 hydrate decomposition, demonstrates the high stability of the material in harsh conditions. Also, a time-resolved observation of the progressing CO2 front is possible and makes membrane incorporation a valuable addition to conventional ex situ gas measurements in reservoir tests of various dimensions. The monitoring technique can significantly contribute to a comprehensive process understanding with respect to the spatial distribution of hydrate formation, dissociation and reformation in the presence of CO2 and CH4.
    Language: English
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  • 127
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    In:  Journal of Quantitative Spectroscopy and Radiative Transfer
    Publication Date: 2020-12-14
    Description: Artificial skyglow is a form of light pollution with wide ranging implications on the environment. The extent, intensity and color of skyglow depends on the artificial light sources and weather conditions. Skyglow can be best determined with ground based instruments. We mapped the skyglow of Berlin, Germany, for clear sky and overcast sky conditions inside and outside of the city limits. We conducted observations using a transect from the city center of Berlin towards a rural place more than 58 km south of Berlin using all-sky photometry with a calibrated commercial digital camera and a fisheye lens. From the multispectral imaging data, we processed luminance and correlated color temperature maps. We extracted the night sky brightness and correlated color temperature at zenith, as well as horizontal and scalar illuminance simultaneously. We calculated cloud amplification factors at each site and investigated the changes of brightness and color with distance, particularly showing differences inside and outside of the city limits. We found high values for illuminance above full moon light levels and amplification factors as high as 25 in the city center and a gradient towards the city limit and outside of the city limit. We further observed that clouds decrease the correlated color temperature in almost all cases. We discuss advantages and weaknesses of our method, compare the results with modeled night sky brightness data and provide recommendations for future work.
    Language: English
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  • 128
    Publication Date: 2020-12-14
    Description: We present a comprehensive overview of the geochemical characteristics and evolution of the carbonatites from the southern Brazilian Platform (Paraná Basin). The carbonatites from different complexes display large compositional variability in terms of abundances of incompatible and rare earth elements. This is in agreement with an origin from heterogeneous lithospheric sources, as confirmed by isotopic data (see Speziale et al., this issue). The characteristic major and trace element abundances of these carbonatites present compelling evidence for invoking liquid unmixing as the main mechanism of their formation and evolution albeit few exceptions. We propose an evolutionary trend for the Brazilian carbonatites, which can be summarized as following: exsolution of the primary Ca- or Mg-carbonatitic liquids systematically takes place at the phonolite-peralkaline phonolite stage of magma differentiation; this is followed by progressive Fe-enrichment and by final emplacement of fluorocarbonatites associated with hydrothermal fluids.
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  • 129
    Publication Date: 2020-12-14
    Description: We analysed gabbroic and dioritic rocks from the Atud igneous complex in the Eastern Desert of Egypt to understand better the formation of juvenile continental crust of the Arabian–Nubian Shield. Our results show that the rocks are the same age (U–Pb zircon ages of 694.5 ± 2.1 Ma for two diorites and 695.3 ± 3.4 Ma for one gabbronorite). These are partial melts of the mantle and related fractionates (εNd690 = +4.2 to +7.3, 87Sr/86Sri = 0.70246–0.70268, zircon δ18O ∼ +5‰). Trace element patterns indicate that Atud magmas formed above a subduction zone as part of a large and long-lived (c. 60 myr) convergent margin. Atud complex igneous rocks belong to a larger metagabbro–epidiorite–diorite complex that formed as a deep crustal mush into which new pulses of mafic magma were periodically emplaced, incorporated and evolved. The petrological evolution can be explained by fractional crystallization of mafic magma plus variable plagioclase accumulation in a mid- to lower crustal MASH zone. The Atud igneous complex shows that mantle partial melting and fractional crystallization and plagioclase accumulation were important for Cryogenian crust formation in this part of the Arabian–Nubian Shield.
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  • 130
    Publication Date: 2020-12-14
    Description: This study of Lithium (Li) isotopes in surface waters and sediments in the catchment of Lake Bangong and the Upper Indus on the western Tibetan Plateau aims to identify processes that control Li isotope variations during weathering under a cold and hyper-arid climate. Additionally, Li isotope ratios in the Yarlung Tsangpo – Brahmaputra River were investigated. The lake and river sediments of Lake Bangong catchment display remarkable low δ7Li values between −4.7‰ and −0.6‰ relative to L-SVEC. Li isotopes in river bed sediments correlate with weathering intensity tracers such as the chemical index of alteration (CIA), K/(Na + K), or Na/Ti, and δ7Li values decrease continuously within the sediment cascade. These observations cannot be explained by mixing of different lithologies but reflects increasing intensity of weathering. The hyper-arid climate on the western plateau results in considerably long sediment residence times, which allows for overcoming the limitation of water availability on chemical weathering reactions. Samples from the Lake Bangong basins display low δ7Li values between +8.1‰ and +11.1‰. The major inflows have dissolved δ7Li values of +6.1‰ and +8.9‰. High Li/Na ratios in the stream waters indicate some contribution of hydrothermal Li. However, low δ7Li values in surface waters result from impeded silicate weathering processes in the thin soils. The samples from Indus headwaters and Yarlung Tsangpo provide evidence for low δ7Li all over the western and southern Tibetan Plateau. Using data of the Bangong Co, the Indus headwaters, and Yarlung Tsangpo, as well as published data from the northeastern plateau, we explore what controls Li isotope variation across the Tibetan plateau. Mass balance calculations suggest that similar proportions of dissolved Li and particulate Li are exported by river water and sediments on the western plateau. In contrast, high δ7Li values around +17‰ of the dissolved load in rivers on the northeastern Tibetan Plateau reflect a particulate Li export flux that is about five times higher than the export flux of dissolved Li. There is no first-order control by silicate weathering rates. The δ7Li differences largely follow the precipitation gradient across the Tibetan Plateau, which results in high net-incorporation of Li into clays on the northeastern but limits soil formation on the western Tibetan Plateau and, therefore limited, processing of lithium in the weathering zone.
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  • 131
    Publication Date: 2020-12-14
    Description: The Huxingshan tungsten deposit (~0.21 Mt at 0.3 wt% WO3) is located in the Jiangnan Massif tungsten ore belt, South China. Here, the W mineralization is restricted to quartz and muscovite-quartz veins intruding variable country rocks of the Lower Cambrian strata. Rb-Sr isochron ages derived from fluid inclusions trapped in muscovite-quartz veins (ca. 134 ± 2 Ma) agree with the zircon U–Pb crystallization age of the associated Huxingshan granite (137.8 ± 0.5 Ma) and may thus suggest a close petrogenetic relationship between both rock types. Zircon εHf (t) values of the Huxingshan granite (−16.2 to +6.6) overlap with those of the specially related metasedimentary Banxi and Lengjiaxi Groups, consistent with melting of Neoproterozoic Yangtze lower crustal materials with mantle melts input to the source. We suggest that the highly differentiated signatures of tungsten and beryllium granite might be inherited from the origin chemistry of source rocks and further modified by highly fractional crystallization rather than by fluid-rock interaction processes. During this process, tungsten and beryllium was enriched in the residual melts/fluids, which finally separated from the solidifying melt body and were introduced into the county rock to precipitate scheelite and beryl along skarn and greisen horizons by large-scale fluid movements. The outlined processes are likely to be coupled to large-scale melting of continental crust and associated granitic magmatism under a regime of subduction of the paleo-Pacific Plate beneath South China and subsequent tearing of the slab. The newly discovered Huxingshan deposit underlines the huge prospecting potential for the northwestern Jiangnan Massif.
    Language: English
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  • 132
    Publication Date: 2020-12-14
    Description: We present new geochemical and isotopic data for rock samples from two island arc volcanoes, Erromango and Vulcan Seamount, and from a 500 m thick stratigraphic profile of lava flows exposed on the SW flank of Vate Trough back‐arc rift of the New Hebrides Island Arc (NHIA). The basalts from the SW rift flank of Vate Trough have ages of ~0.5 Ma but are geochemically similar to those erupting along the active back‐arc rift. The weak subduction component in the back‐arc basalts implies formation by decompression melting during early rifting and rifting initiation by tectonic processes rather than by lithosphere weakening by arc magma. Melting beneath Vate Trough is probably caused by chemically heterogeneous and hot mantle that flows in from the North Fiji Basin in the east. The melting zone beneath Vate Trough back‐arc is separate from that of the arc front, but a weak slab component suggests fluid transport from the slab. Immobile incompatible element ratios in South NHIA lavas overlap with those of the Vate Trough depleted back‐arc basalts, suggesting that enriched mantle components are depleted by back‐arc melting during mantle flow. The slab component varies from hydrous melts of subducted sediments in the Central NHIA to fluids from altered basalts in the South NHIA. The volcanism of Erromango shows constant compositions for 5 million years, that is, there is no sign for variable depletion of the mantle or for a change of slab components due to collision of the D'Entrecasteaux Ridge as in lava successions further north.
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  • 133
    Publication Date: 2020-12-14
    Description: Diffuse glow has been observed around brightly lit cities in nighttime satellite imagery since at least the first publication of large scale maps in the late 1990s. In the literature, this has often been assumed to be an error related to the sensor, and referred to as “blooming”, presumably in relation to the effect that can occur when using a CCD to photograph a bright light source. Here we show that the effect seen on the DMSP/OLS, SNPP/VIIRS-DNB and ISS is not only instrumental, but in fact represents a real detection of light scattered by the atmosphere. Data from the Universidad Complutense Madrid sky brightness survey are compared to nighttime imagery from multiple sensors with differing spatial resolutions, and found to be strongly correlated. These results suggest that it should be possible for a future space-based imaging radiometer to monitor changes in the diffuse artificial skyglow of cities.
    Language: English
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  • 134
    Publication Date: 2021-01-09
    Description: Despite the amount of research focused on the Alpine orogen, significant unknowns remain regarding the thermal field and long term lithospheric strength in the region. Previous published interpretations of these features primarily concern a limited number of 2D cross sections, and those that represent the region in 3D typically do not conform to measured data such as wellbore or seismic measurements. However, in the light of recently published higher resolution region specific 3D geophysical models, that conform to secondary data measurements, the generation of a more up to date revision of the thermal field and long term lithospheric yield strength is made possible, in order to shed light on open questions of the state of the orogen. The study area of this work focuses on a region of 660 km x 620 km covering the vast majority of the Alps and their forelands, with the Central and Eastern Alps and the northern foreland being the best covered regions.
    Language: English
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  • 135
    Publication Date: 2021-01-09
    Description: This data set is the part 8 of a series reporting chemical data for accessory minerals from felsic igneous rocks. Compositional data were acquired by electron-probe microanalysis (EPMA) between about 1995 and 2005 on surface rocks and borehole samples. This data set assembles the results of EPMA of fluorapatite from felsic rocks representing three groups of granites in the Erzgebirge−Vogtland metallogenic province of Germany emplaced in the late Carboniferous: F-poor biotite granites, F-poor two-mica granites, and P-F-rich Li-mica granite. In these rocks, fluorapatite is typically omnipresent. It has to be noted that apatite has not yet been in the focus of mineralogical studies of the granites in this province and a comprehensive survey of its compositional signature and variability in space and time is still pending. However, the data listed in this data set provide a valuable glimpse into the similarities and differences in apatite chemistry between geochemically distinct felsic rocks, and into the evolution in composition from early to late crystallizing apatite populations. The data underpin that apatite is a sensitive monitor of the compositional properties of the media (melts and fluids) from which it was deposited or with which it interacted. Apatite from the studied rocks is basically fluorapatite with little or no Cl and OH detected respectively inferred. Elemental variations are observed at various scales, i.e., between granite groups, subsequently crystallized sub-intrusion within composite massifs, grains present in a single thin section, or between the center and the rim of a particular grain. These variations in particular refer to the following elements: Mn, Fe, Na, and the rare-earth elements (REE). For example, measured Mn concentrations range from 0.15 to 8.8 wt% MnO. The data set contains the complete pile of electron-microprobe analyses for fluorapatite (APAT-ERZ-2020). The data are presented as Excel (xlsx) and tab-delimited text (txt) formats. The content of the tables and further information on the granites and regional geology are provided in the data description file.
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  • 136
    Publication Date: 2021-01-09
    Description: The data publication contains a dataset for fast assessment of earthquakes and early warning based on seismic waveforms. The dataset encompasses Italy and surrounding refions. Due to the large scale of the dataset, it is intended for use in machine learning. A similar dataset for Japan, with the same specifications as the one provided in this data publications, can be obtained using the scripts at https://github.com/yetinam/TEAM
    Language: English
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  • 137
    Publication Date: 2021-01-09
    Description: In January 2020, a swarm of earthquakes started under Thorbjorn volcano, Reykjanes, SW Iceland, associated to the uplift of up to 0.5 cm per day. Concern in Iceland is growing and the Iceland Meteorological Office suggested that possibly magma was intruded in the crust at shallow depth (3 to 9 km). The GFZ is starting a seismological Hazard and Risk Team (HART) in cooperation with IMO, ISOR and the University of Iceland. This dataset comprise a selection of waveforms recorded along a fibre length of 21 km. The interrogator is located in Grindavik and is connected to a standard telecom cable. Waveform data are available from the GEOFON data centre, under network code 5J.
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  • 138
    Publication Date: 2021-01-09
    Description: The DFG Priority Program 1803 "EarthShape - Earth Surface Shaping by Biota” (www.earthshape.net, short description of the project below) installed a meteorological station network consisting of four stations between ~}26 °S to {~38 °S in the Coastal Cordillera of Chile, South America. The stations are intended to provide baseline meteorological data along the climate and ecological gradient investigated in the EarthShape program. The stations are located in the EarthShape study areas, encompassing desert, semi-desert, mediterranean, and temperate climate zones. Each station is configured to include sensors that record precipitation at ground level, radiation at 2.8 m height, wind at 3 m height, 25 cm depth soil temperature, soil water content and bulk electrical conductivity, 2 m air temperature and relative humidity, and barometric pressure at 30-minute intervals. The data recording started in March/April 2016. The EarthShape project runs until December 2021. Data collection will continue until that date, and potentially longer depending on available funds. This publication provides two sets of data: raw data and processed data. The raw data contains 2 file types per meteorological station: (1) all measured parameters of the whole dataset measured in 30 minutes intervals as downloaded from the station. Furthermore, we provide (2) one table per station of high-resolution precipitation events, measured in 5 min. intervals that were triggered during rain events at each station. The processed data consists of a continuous timeseries of observations since the activation of each station. The processing consists of the exclusion of erroneous data, caused by maintenance of the weather-stations and sporadic malfunction of sensors detected during data screening. The excluded data is communicated in a logfile (excel table), comments from data screening, solar eclipse and others are summarized in history files (ASCII ). the full description of the data and methods is provided in the data description file (Data description file).
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  • 139
    Publication Date: 2020-12-23
    Description: The GRACE and GRACE-FO satellites observe the redistribution of mass in terrestrial water storage, ice sheets, oceans, atmosphere, and solid Earth. Because GRACE data is typically accumulated into monthly-mean gravity fields, an a priori background model, namely the Atmosphere and Ocean Dealiasing Level 1B (AOD1B) product, is applied to remove non-tidal variability that would otherwise alias into the monthly solutions. The main disadvantage of AOD1B RL06 compared to its previous release is that it does not simulate the dynamics beneath the Antarctic ice shelves, which can have a strong influence on global ocean circulation. The primary motivation for this work is the development of the new release of AOD1B, but the performed model experiments can also provide useful insight into the influence processes in the Southern Ocean have on global ocean dynamics. To be able to test various model experiments, as well as to compare GRACE gravity field solutions, validation against in situ measured ocean bottom pressure (OBP) is used. The validation is somewhat better suited for submonthly variability of the ocean models than for long-term signals measured by GRACE because the in situ time series are affected by the errors in trend and drift removal on longer temporal scales. The difference between the pointwise in situ and the area-averaging GRACE measuring technique also influences the comparison. It is shown that post-processing choices can severely impact the results of the validation of GRACE fields, so if different solutions are compared, their post-processing needs to be identical. Validation against in situ OBP is used to compare the EGSIEM combined GRACE solution with its five contributing datasets. It is shown that the combined solution is very close to the leading CSR RL05 and ITSG-Grace2016 solutions, outperforming the others. To investigate whether GRACE is able to detect submonthly signals, the ITSG-Grace2016 daily Kalman solution, from which the submonthly atmospheric and oceanic variability has been removed with AOD1B RL05, is validated against in situ OBP. The results show that GRACE successfully captures some submonthly variability that is not predicted by the incorporated dealiasing model. As a first step towards AOD1B RL07, the dynamics beneath the Antarctic ice shelves are implemented into the model used as the oceanic part of AOD1B, the Max Planck Institute Ocean Model (MPIOM). The bathymetry is modified to include the areas under the ice shelves and two new model experiments are performed: in one those regions are treated as open ocean, while in the other the atmospheric forcing is modified to simulate the ice shelves. The changes caused by such modifications are not limited only to the Southern Ocean, but also affect the Northern Atlantic, confirming the role the Weddell Sea has on the meridional overturning circulation. While surface changes exceed the typical variability only in a few regions, the differences at the bottom of the ocean are larger. The changes caused by ice shelf forcing are of the same order of magnitude in the vicinity of the ice shelves, but much smaller globally. A comparison with the GLORYS2v4 ocean reanalysis shows that the new model experiments are closer to the reanalysis, especially in the regions where the original MPIOM experiment performs the worst. The analysis of OBP variability points out some possible issues that need to be fixed before publishing the new AOD1B release. Validation against in situ OBP, however, shows that the modifications are without a doubt in the right direction: the new model experiment has increased relative explained variances in the 1 - 3 days band by approximately 5 % throughout Pacific, and by more than 10 % in the Antarctic Circumpolar Current region.
    Description: Die GRACE- und GRACE-FO-Satelliten beobachten die Umverteilung von Masse in terrestrischen Wasserspeichern, Eisdecken, Ozeanen, Atmosphäre und fester Erde. Da GRACE-Daten in der Regel in monatlichen gemittelten Schwerefeldern gesammelt werden, wird ein a priori Hintergrundmodell Atmosphere and Ocean Dealiasing Level 1B (AOD1B) angewendet, um nicht-gezeitenbedingte Schwankungen zu beseitigen, die andernfalls zu einem Alias-Effekt in den monatlichen Lösungen führen würden. Der Hauptnachteil von AOD1B RL06 im Vergleich zu seiner Vorgängerversion besteht darin, dass die Dynamik unter den Antarktis-Eisschelfs, die einen starken Einfluss auf die globale Ozeanzirkulation haben kann, nicht simuliert wird. Die Hauptmotivation für diese Arbeit ist die Entwicklung des neuen Releases von AOD1B, die durchgeführten Modellexperimente können jedoch auch nützliche Einblicke in den Einfluss von Prozessen im Südpolarmeer auf die globale Ozeandynamik liefern. Um verschiedene Modellexperimente testen und GRACE-Schwerefeldlösungen vergleichen zu können, wird eine Validierung gegen den in situ gemessenen Meeresbodendruck (OBP) durchgeführt. Die Validierung ist für die submonatliche Variabilität der Ozeanmodelle etwas besser geeignet als für die von GRACE gemessenen Langzeitsignale, da die In-situ-Zeitreihen auf längeren Zeitskalen von Trend- und Driftentfernungenfehlern beeinflusst werden. Der Unterschied zwischen der punktweisen in situ- und der flächenmittelnden GRACE-Messtechnik beeinflusst auch den Vergleich. Es wird gezeigt, dass die Auswahl der Postprozessierung die Validierungsergebnisse von GRACE-Feldern erheblich beeinflussen kann. Wenn also verschiedene Lösungen verglichen werden, muss die Postprozessierung identisch sein. Die Validierung gegen In-situ-OBP wird verwendet, um die in EGSIEM Projekt kombinierte GRACE-Lösung mit ihren fünf beitragenden Datensätzen zu vergleichen. Es wird gezeigt, dass die kombinierte Lösung den führenden CSR RL05- und ITSG-Grace2016-Lösungen sehr nahe kommt und die anderen übertrifft. Um zu untersuchen, ob GRACE in der Lage ist, submonatliche Signale zu erkennen, wird die tägliche ITSG-Grace2016-Kalman-Lösung, aus der die submonatliche atmosphärische und ozeanische Variabilität mit AOD1B RL05 entfernt wurde, gegen in situ OBP validiert. Die Ergebnisse zeigen, dass GRACE gewisse submonatliche Variabilitäten erfolgreich erfasst, die vom integrierten Dealiasing-Modell nicht vorhergesagt werden. Als erster Schritt in Richtung AOD1B RL07 wird die Dynamik unter den Antarktis-Eisschelfs in das Max Planck Institute Ocean Model (MPIOM) implementiert, das als ozeanischer Teil von AOD1B verwendet wird. Die Bathymetrie wird modifiziert, um die Bereiche unter den Eisschelfen einzubeziehen, und es werden zwei neue Modellexperimente durchgeführt: In einem Experiment werden diese als offener Ozean behandelt, während im anderen der atmosphärische Antrieb modifiziert wird, um die Eisschelfe zu simulieren. Die durch solche Modifikationen verursachten Veränderungen beschränken sich nicht nur auf das Südpolarmeer, sondern betreffen auch den Nordatlantik, was die Rolle des Weddellmeeres für die meridionale Umwälzzirkulation bestätigt. Während die Oberflächenveränderungen die typische Variabilität nur in wenigen Regionen überschreiten, sind die Unterschiede am Meeresboden größer. Die Veränderungen, die durch den Eisschelfantrieb verursacht werden, sind in der Nähe der Eisschelfs in der gleichen Größenordnung, global jedoch viel geringer. Ein Vergleich mit der Ozean-Reanalyse GLORYS2v4 zeigt, dass die neuen Modellexperimente näher an der Reanalyse liegen, insbesondere in den Regionen, in denen das ursprüngliche MPIOM-Experiment am schlechtesten abschneidet. Die Analyse der OBP-Variabilität zeigt einige mögliche Probleme auf, die vor der Veröffentlichung der neuen Version des AOD1B-Produkts behoben werden müssen. Die Validierung mit In-situ-OBP zeigt jedoch, dass die Modifikationen zweifellos in die richtige Richtung weisen: Das neue Modellexperiment hat die relativen erklärten Varianzen im Bereich von 1 - 3 Tagen im gesamten pazifischen Raum um ungefähr 5 % erhöht und um mehr als 10 % in der Region der Antarktische Zirkumpolarströmung.
    Language: English
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  • 140
    Publication Date: 2020-12-23
    Description: Environmental scientists aim at understanding not only single components but systems, one example is the flood system; scientists investigate the conditions, drivers and effects of flood events and the relations between them. Investigating environmental systems with a data-driven research approach requires linking a variety of data, analytical methods, and derived results. Several obstacles exist in the recent scientific work environment that hinder scientists to easily create these links. They are distributed and heterogeneous data sets, separated analytical tools, discontinuous analytical workflows, as well as isolated views to data and data products. We address these obstacles with the exception of distributed and heterogeneous data since this is part of other ongoing initiatives. Our goal is to develop a framework supporting the data-driven investigation of environmental systems. First we integrate separated analytical tools and methods by the means of a component-based software framework. Furthermore we allow for seamless and continuous analytical workflows by applying the concept of digital workflows, which also demands the aforementioned integration of separated tools and methods. Finally we provide integrated views of data and data products by interactive visual interfaces with multiple linked views. The combination of these three concepts from computer science allows us to create a digital research environment that enable scientists to create the initially mentioned links in a flexible way. We developed a generic concept for our approach, implemented a corresponding framework and finally applied both to realize a “Flood Event Explorer” prototype supporting the comprehensive investigation of a flood system. In order to implement a digital workflow our approach intends to precisely define the workflow’s requirements. We mostly do this by conducting informal interviews with the domain scientists. The defined requirements also include the needed analytical tools and methods, as well as the utilized data and data products. For technically integrating the needed tools and methods our created software framework provides a modularization approach based on a messaging system. This allows us to create custom modules or wrap existing implementations and tools. The messaging system (e.g. pulsar) then connects these individual modules. This enables us to combine multiple methods and tools into a seamless digital workflow. The described approach of course demands the proper definition of interfaces to modules and data sources. Finally our software framework provides multiple generic visual front-end components (e.g. tables, maps and charts) to create interactive linked views supporting the visual analysis of the workflow’s data.
    Language: English
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  • 141
    Publication Date: 2021-01-21
    Description: New apatite fission track (AFT) and (U–Th)/He (AHe) data from two sections recording Cretaceous-Cenozoic clastic successions (La Flecha - La Troya Sur creeks) in the northern sector of the Central Precordillera of Argentina are presented. The results show that the Ciénaga del Río Huaco, Puesto la Flecha and Vallecito Fms. would have crossed the 60 °C isotherm during burial, while the middle sector of the Vinchina Fm. would not have reached temperatures higher than 55 °C. Multimethod inverse thermal modeling suggests that the AFT ages of all the studied levels would not have been completely reset and allow inferring that the partial retention zone for the AHe system (AHe-PRZ) would have been reached during the Miocene in levels between the Vallecito and Vinchina Fms. Our 1D-modeling results for the Ciénaga del Río Huaco, Puesto la Flecha and Vallecito Fms. show that the maximum temperature would have been reached at ~15 Ma, with a sedimentary thickness of ~2750 m and a heat flow of 65 mW/m2. From these data, a geothermal gradient of ~27 °C/km at this time could be inferred. In turn, the Vinchina and Zapallar Fms. would have reached their maximum temperature at ~2 Ma, under a cooler thermal regime (20 mW/m2) and with an estimated geothermal gradient of 〈15 °C/km. Thus, a complex time-temperature trajectory is proposed. Maximum and cooling temperatures reached by each unit do not correspond in all cases to the maximum burial and exhumation times. Comparison of the thermal modelling from this work with those carried out by other authors for sections immediately to the north allows us to infer that the thermal regime within the Vinchina basin has important lateral variations. Finally, AFT and AHe analyzes carried out in this work constitute a baseline database of the thermal regime, which is necessary for future multiproxies studies that are being done to evaluate the preservation of primary thermal signals, and thus check their reliability for pealeoclimatic and paleoenvironmental interpretations.
    Language: English
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  • 142
    Publication Date: 2021-01-22
    Description: Soil Carbon (C) is central to the functioning of ecosystems and climate change mitigation. It represents the largest terrestrial pool and much of it, is stored in forest soils. Soil Organic Carbon (SOC) in a forest varies not only laterally, but also vertically (i.e., with depth). However, the SOC content of forest soil horizons has not been investigated over large scales, despite its importance for framing our understanding of soil function. Visible–Near Infrared (vis–NIR) reflectance spectroscopy enables rapid and cost-effective examination of forest SOC distribution, both laterally and vertically. This study aims to evaluate the potential of vis–NIR spectroscopy for classifying and predicting the SOC concentration of organic and mineral horizons in forests of the Czech Republic. We investigated 1080 forest sites across the country, each with five soil horizons, representing the Litter (L), Fragmented (F), and Humus (H) organic horizons, as well as the A1 (depth of 2–10 cm) and A2 (depth of 10–40 cm) mineral horizons. We, then, used Support Vector Machines (SVMs) to classify the soil horizons based on their spectra and also to model the SOC concentration of (i) the profile (organic and mineral horizons together), (ii) only the organic horizons, (iii) only the mineral horizons, and (iv) each individual horizon separately. The models were validated using 10-repeated 10-fold cross-validation. Results show that the SVM with radial basis kernel could accurately classify the soil horizons (Correct Classification Rate (CCR) of 70% and Kappa coefficient of 0.63). The SOC model developed for the soil profile performed well (R2 = 0.76 and RMSE = 1.63%). The model of the combined organic horizons was considerably more accurate than that of the combined mineral horizons (R2 = 0.78 and R2 = 0.53, respectively). Estimates of SOC in the individual soil horizons had R2 values greater than 0.63 but those of the F and A1 models were better with R2 〉 0.70. The study indicates that vis–NIR spectroscopy can effectively characterize the SOC concentration of the highly variable forest soil horizons in the Czech Republic.
    Language: English
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  • 143
    Publication Date: 2021-01-20
    Description: Soil plays an important role in the context of vine growth and wine production; particularly soil structure which gov-erns plant water uptake. Therefore, soil physical and hydrological properties were studied at Neuras vineyard, located near the Namib Desert. Water is scarce in this environment and wine production is limited to few vineyards in Namibia, overall. Managed plots and unmanaged nearby sites were investigated using field and laboratory methods. Viticultural techniques were noted and management related aspects were gathered in an interview. Datasets from two sampling trips in 2014 and 2016 were generated. In 2014, older vineyard soils displayed different properties than unmanaged soils or a younger vineyard, showing lower bulk densities and higher total porosities, with increased organic carbon and ni-trogen contents. In 2016, the unmanaged reference plot differed from managed plots mainly in terms of lower electrical conductivity and higher cation exchange capacity. In managed soils contents of Smectites and Vermiculites were higher, while those of Chlorites and Illites were lower. Soil water retention properties were also altered, in line with structural changes indicated by bulk density and total porosity. These differences were more pronounced in vineyards of differ-ent ages than in those with even ages and indicate overall very different soil and soil structural conditions for the older versus the younger vineyards affecting vine growth.
    Language: English
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  • 144
    Publication Date: 2021-01-27
    Description: The active seismic method is a standard tool for studying the Earth's lithosphere. On scales from centimeters to kilometers, academic research is generally interested in highly complex geological targets such as volcanic edifices, crustal faults or salt environments. In order to properly image these structures, large and expensive multichannel acquisitions with a high offset-to-target depth ratio are required. In practice, however, these are often hardly affordable for academic institutions, with the result that reflections often only poorly illuminate laterally variable structures, which in turn compromises imaging and interpretation. As in common practice, most of the processing and interpretational steps are tailored to the reflected wavefield, faint diffracted contributions are typically considered as an unwanted by-product. In recent works, however, it has been shown that diffractions possess unique properties which bear the potential to overcome the aforementioned limitations. Wave diffraction occurs at geodynamically important features like faults, pinch-outs, erosional surfaces or other small-scale scattering objects and encodes sub-wavelength information on the scattering geometry. Since diffracted waves do not obey Snell's Law, they provide superior illumination compared to reflected waves. Moreover, due to their passive-source like radiation, they encode their full multichannel response in prominent data subsets like the zero-offset section. In order to explore what can be learned from the faint diffracted wavefield, we use academic seismic data from the Santorini-Amorgos Tectonic Zone (SATZ) in the Southern Aegean Sea. This is an area well known for its local complexity, indicated by the occurrence of extended fault systems and volcanic edifices as well as a complex acoustic basement. As the available seismic data in this region were acquired using a relatively short streamer, the SATZ represents a classical example for the need of innovative methods for seismic processing and interpretation. By means of a robust and computationally efficient scheme for the extraction of diffractions that models and adaptively subtracts the reflected wavefield from the data, we reveal a rich diffracted wavefield from zero-offset data. On the one hand, we use the diffraction-only sections for analysing the small-scale structural complexity and demonstrate that the geological interpretation can benefit from these observations. On the other hand, we use the diffractions to estimate insightful wavefront attributes in the zero-offset domain. Based on these attributes, we perform wavefront tomography to obtain depth-velocity models. Compared to depth-velocity models derived from the reflected contributions, the diffraction-based velocity model fits the data significantly better. After refining this velocity model, we perform prestack depth migration and obtain highly valuable depth converted seismic sections. Concluding our results, we strongly encourage the incorporation of diffractions in standard processing and interpretational schemes.
    Language: English
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  • 145
    Publication Date: 2021-01-27
    Description: Mesospheric winds from three longitudinal sectors at 65°N and 54°N latitude are combined to diagnose the zonal wave numbers (m) of spectral wave signatures during the Southern Hemisphere sudden stratospheric warming (SSW) 2019. Diagnosed are quasi‐10‐ and 6‐day planetary waves (Q10DW and Q6DW, m = 1), solar semidiurnal tides with m = 1, 2, 3 (SW1, SW2, and SW3), lunar semidiurnal tide, and the upper and lower sidebands (USB and LSB, m = 1 and 3) of Q10DW‐SW2 nonlinear interactions. We further present 7‐year composite analyses to distinguish SSW effects from climatological features. Before (after) the SSW onset, LSB (USB) enhances, accompanied by the enhancing (fading) Q10DW, and a weakening of climatological SW2 maximum. These behaviors are explained in terms of Manley‐Rowe relation, that is, the energy goes first from SW2 to Q10DW and LSB, and then from SW2 and Q10DW to USB. Our results illustrate that the interactions can explain most wind variabilities associated with the SSW.
    Language: English
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  • 146
    Publication Date: 2021-01-26
    Description: We present a 1D shear‐velocity model for Los Humeros geothermal field (Mexico) obtained from three‐component beamforming of ambient seismic noise, imaging for the first time the bottom of the sedimentary basement ∼5km below the volcanic caldera, as well as the brittle‐ductile transition at ∼10km depth. Rayleigh‐wave dispersion curves are extracted from ambient seismic noise measurements and inverted using a Markov chain Monte Carlo scheme. The resulting probability density function provides the shear‐velocity distribution down to 15 km depth, hence, much deeper than other techniques applied in the area. In the upper 4 km, our model conforms to a profile from local seismicity analysis and matches geological structure inferred from well logs, which validates the methodology. Complementing information from well logs and outcrops at the near surface, discontinuities in the seismic profile can be linked to geological transitions allowing us to infer structural information of the deeper subsurface. By constraining the extent of rocks with brittle behavior and permeability conditions at greater depths, our results are of paramount importance for the future exploitation of the reservoir and provide a basis for the geological and thermodynamic modeling of active superhot geothermal systems, in general.
    Language: English
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  • 147
    Publication Date: 2021-01-29
    Description: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The Membach station is located near the river Vesdre. It consists of a 130 m long gallery excavated in the side of the valley that rises to the Hautes Fagnes plateau. At the end of the gallery, there are two rooms, located at ~45 m below the ground surface. Room 1 is dedicated to absolute gravity and seismic measurements; room 2 houses the superconducting gravimeter. The structure of the gallery and the rooms is in reinforced concrete. It was built in the early 1970s to monitor the seismic activity in the vicinity of the Gileppe and Eupen water reservoirs. Works were performed contemporeanously with the raising of the Gileppe dam. The gallery has been excavated in low-porosity argillaceous sandstone with quartzitic beds. As a function of rainfall and seasonal effects, gravity variations up to 40 nms-2 have been observed, and are mostly due to groundwater changes in the vadose zone above the underground laboratory (Van Camp et al., 2006). Strong rainfall induces rapid gravity decreases (Meurers et al 2007; Delobbe et al., 2019). At the surface, a beech forest. Absolute gravity measurements have been performed on average every month since 1996, using the FG5#202 gravimeter and the station is also the reference point for the Belgian gravity network. The SG GWR#C021 has been operating continuously since 1995 August so that, since 2017 September 18, it holds both records for the longest continuous time spent measuring gravity variations in the same place and for the longest superconducting levitation of an artefact (Van Camp et al., 2017). For high precision works like Earth tides analysis on long time series, data should not be used before 1998 June 12, when the original "TIDE" card in the SG electronics was replaced by the "GGP" one. Filters are different, and so are the transfer functions. Moreover, in this early period, the SG suffered from numerous technical issues, causing several changes in the amplitude and phase calibrations and making it difficult to ensure that the data are as reliable as after 1998 June.
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  • 148
    Publication Date: 2021-01-28
    Description: SEVA is a scalable exploration tool that supports users to conduct change detection based on optical Sentinel-2 satellite observations. It supports the following essential steps of change detection: a) exploration and selection of optical satellite images to recognize proper data for the current application scenario, b) automated extraction of changes from the optical satellite images, c) analysis of errors and d) assessment and interpretation of the extracted changes.
    Language: English
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  • 149
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    Unknown
    GFZ Data Services
    Publication Date: 2021-01-28
    Description: This package provides a set of tools to read, manipulate and convert seismic waveforms generated by DAS systems. In particular, the ones saved in TDMs format: - dasconv: This utility lets you convert and manipulate seismic waveforms in TDMs format and export them into MiniSEED. - tdmsws (experimental) - a stand-alone implementation of the FDSN Dataselect web service, which is able to serve miniSEED data extracted from a folder with TDMS files.
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  • 150
    Publication Date: 2021-01-28
    Description: The 563.7 ± 6.1 Ma old, early-syntectonic Mon Repos complex is a predominantly metaluminous, magnesian, calc-alkalic granodioritic to granitic intrusion. Major and trace element variations imply that the rocks evolved through fractional crystallization processes involving amphibole, biotite, Fe-Ti oxides, zircon, and apatite. Rocks less evolved than granodiorite show evidence of hornblende accumulation. Initial Sr (87Sr/86Sr: 0.7090–0.7111) and Nd (εNd: −5.3 to −12.3) isotopic compositions of the granodiorites and granites are highly heterogeneous and vary with SiO2 contents indicating that assimilation of older crustal components occurred. Initial 206Pb/204Pb (16.65–17.65) and 207Pb/204Pb ratios (15.52–15.60) are similar to other mafic-intermediate complexes from the Damara belt. One monzodiorite and two quartz monzonites are K2O-, LILE-, and HFSE enriched and have similar SiO2 contents as the granodiorites. These samples are similar to post-collisional mafic magmas from elsewhere in the world. Their ε Nd values (−3.8 to −4.3), 87Sr/86Sr ratios (0.7051–0.7073) and trace-element characteristics imply that their unexposed parental melts are derived from a lithospheric mantle source that was contaminated and metasomatized by crustal material during ancient subduction processes. The data are explained by assuming a “flat” subduction model where melting predominantly involves ancient continental mantle lithosphere and crust with limited, if any, melting of the underlying asthenospheric mantle. During flat subduction, a sliver consisting of buoyant oceanic lithosphere was amalgamated with the base of the ancient continental lithosphere of the overriding plate. The oceanic mantle lithosphere and the oceanic crust dehydrated (but did not melt) and these fluids lowered the solidus of the overlying continental mantle lithosphere and crust. This scenario can explain the occurrence of rare K2O- and LILE-enriched monzodiorites and quartz monzonites with crustal-like isotopic compositions observed in this study as well as some more alkaline rocks in the belt. Because the metasomatized continental lithospheric mantle has lower solidus temperatures than peridotitic mantle, it is very likely that such metasomatized rocks may melt early during flat subduction. Thus, K2O-enriched monzodiorites to monzogranites are not restricted to late stages of the evolution of an orogen but may already form at the onset of an orogeny.
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  • 151
    Publication Date: 2021-01-28
    Description: Along more than 1000 km, the boundary between the Pampean and Famatinian belts separates the Cambrian magmatism to the east (540-515 Ma) from the easternmost granitic rocks ascribed to the Famatinian orogeny to the west (early Ordovician). The geochronological and geochemical study presented in this work has revealed the first Cambrian magmatism in the Sierras de Aconquija and Cumbres Calchaquíes at the northeastern edge of the Famatinian belt. Pabellón (522 ± 2.8 Ma) and Ñuñorco Grande (478.3 ± 2.3 Ma) intrusive units form part of the small plutons exposed together in the Tafí del Valle area, which have been related according to their geochemical characteristics. The good correlation observed between ages and characteristic geochemical signatures have motivated the comparison with other intrusive complexes along the Pampean and eastern Famatinian belts, resulting in regional diagnostic geochemical features and a petrogenetic and evolutive proposal for the Cambrian and early Ordovician magmatism in the eastern Sierras Pampeanas. Easternmost early Ordovician granitic rocks constitute a calcic, weak to moderately peraluminous series. They are Sr-rich tonalitic to monzogranitic magmas (SiO2 〉62 %wt.) with steep REE patterns, positive and negative Eu anomalies, high Sr/Y and moderate Ce/Yb ratios. Accordingly, the water-fluxed melting of a mafic source under high to moderate pressures may be involved in the origin of silica- and Ca-rich parental magma. The shallower evolution of these melts consists of Pl-dominated fractionation trends that finally constituted Pl-rich crystal mushes (tonalites) and more felsic residual liquids. Regarding Cambrian granodiorites and monzogranites, any petrogenetic scheme must consider the magnesian, high-K calc-alkalic characteristics for a short-range silica variation, low to moderate peraluminosity and high zircon saturation temperatures (〉850 °C). Source conditions are determined by the presence of Pl and Hbl in the solid assemblage based on the REE patterns. These geochemical characteristics point to the extensive HT-LP melting of a dominantly crustal source, probably assisted by the injection of hot H2O-rich mafic melts.
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  • 152
    Publication Date: 2021-01-29
    Description: The high-pressure phase transition of strontianite (SrCO3) was investigated at ambient temperature by means of powder and single-crystal X-ray diffraction. The samples were compressed in a diamond anvil cell to a maximum pressure of 49 GPa. Structure refinements confirm the existence of SrCO3 in the low pressure aragonite-type phase Pmcn (62) up to about 26 GPa. Above this pressure, SrCO3 transforms into a high-pressure phase with post-aragonite crystal structure Pmmn (59). Fitting the volume extracted from the compression data to the third-order Birch–Murnaghan equation of state for the low-pressure phase of SrCO3 yields K0=62.7(6) GPa and K′0=3.2(1), and for the high-pressure phase this yields K0=103(10) GPa and K′0=2.3(6). The unit cell parameters change non-uniformly, with the c axis being 4 times more compressible than the a and b axes. Our results unequivocally show the existence of a Pmmn structure in SrCO3 above 26 GPa and provide important structural parameters for this phase.
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  • 153
    Publication Date: 2021-02-02
    Description: Sedimentary exhalative (SEDEX) deposits are a subset of sediment-hosted massive sulfide deposits and provide our dominant resource of Zn. In the SEDEX model, base metals (Zn, Pb, Fe) are hydrothermally vented into sulfidic (euxinic) seawater and deposited coevally with the organic-rich mudstone host rock, resulting in laterally extensive layered mineralization. In the Selwyn Basin (Canada) at Macmillan Pass, two deposits (Tom, Jason) are well preserved in a succession of Upper Devonian mudstones and are considered type-characteristic examples of the SEDEX deposit model. As with a number of SEDEX deposits, at Macmillan Pass barite is abundant in the succession hosting hydrothermal mineralization. Early work presented a hydrothermal model for barite formation, in which barite coprecipitated with base metal sulfides in a redox-stratified water column. Recently, however, studies have both proposed an alternative diagenetic model for barite formation and provided more precise constraints on the chemistry of the hydrothermal fluid that entered the vent complexes. Here, we present a new model for Macmillan Pass in which sulfide mineralization occurred entirely within the subsurface. The introduction of hot (300°C) hydrothermal fluids into the shallow subsurface (〈1-km depth) resulted in the thermal degradation of organic matter and generated CO2; this promoted barite dissolution, which both provided a source of sulfate for thermochemical sulfate reduction and increased the porosity and permeability within the system. Importantly, there was clear potential for the development of positive feedbacks and self-organization between diagenetic and hydrothermal processes, resulting in highly efficient ore-forming systems. In contrast to the SEDEX model, alteration footprints will be controlled by the mass transfer involved in (barite) replacement reactions rather than hydrothermal venting, and exploration criteria at a district scale should strongly favor highly productive continental margins.
    Language: English
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  • 154
    Publication Date: 2021-02-02
    Description: The application of Raman spectroscopy for the identification and characterization of minerals and related materials has increased appreciably during recent years. Raman spectroscopy has proven to be a most valuable and versatile analytical tool. Successful applications cover virtually all the mineralogical sub-disciplines, and have become more numerous in geochemistry. We present a general summary of present applications, illustrated by selected examples. In addition, we briefly point out several aspects of spectral acquisition, data reduction, and interpretation of Raman results that are important for the application of Raman spectroscopy as a reliable analytical tool.
    Language: English
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  • 155
    Publication Date: 2021-02-03
    Description: The mineral exploration industry is again in a boom to provide new resources of critical raw materials as well as base and precious metals. This is evident from the globally increased expenditure reported for 2018 (International Mining 2018). Global demand towards green technologies requires sustainable flow of primary raw materials into the so‐called whole value chain. Without exploring in new areas (greenfields), the chance of finding giant deposits or providing fresh resources to the market and sustaining the value‐chain loop would be minimal. However, it is convenient in the short term to explore in brownfield areas and near mines to make use of existing infrastructures and to avoid new environmental footprints. In such circumstances, the mineral exploration industry is further challenged to not only provide high‐quality and high‐resolution deep‐targeting solutions but also to do it in a cost‐ and environmentally effective way. This is particularly significant in the European Union (EU) and in regions with thick cover, requiring new and much more sensitive exploration technologies for direct deposit targeting and geological characterization. In addressing these, there are several research and innovation initiatives worldwide trying to tackle some of these challenges like, to list a few, Smart Exploration in the EU and Metal Earth in Canada. There are also a number of cooperative research centre (CRC) projects in Australia as well as in Africa where favourable geology exists but exploration is challenged to find new “tier 1” deposits at depth (+500 m). This Special Issue of Geophysical Prospecting contains 18 articles and is coordinated by a number of experts involved in the Smart Exploration project (Malehmir et al. 2019). Eight of the included articles are from the project itself, and highlight the progress being made in this topic with a particular focus on legacy data and the value and potential such data have for deep‐targeting and high‐resolution imaging. The Special Issue, through showcases, reports the remarkable progress being made in overcoming the perceived high exploration cost for mineral exploration particularly for deeper targets. In the following, we provide a brief introduction to the papers included in this Special Issue. The included articles are divided into three main categories: legacy and exploration data, innovative solutions and state‐of‐the‐art equipment. Interested readers are also encouraged to check the three earlier special volumes on similar topics by Eaton, Milkereit and Salisbury (2003 and the references therein), Malehmir et al. (2012 and the references therein) and Buske, Bellefleur and Malehmir (2015 and the references therein).
    Language: English
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  • 156
    Publication Date: 2021-02-01
    Description: Artificial light at night (ALAN) can have negative impacts on the health of humans and ecosystems.1, 2, 3, 4 Marine organisms, including coral reefs in particular, rely on the natural light cycles of sunlight and moonlight to regulate various physiological, biological, and behavioral processes.5, 6, 7, 8 Here, we demonstrate that light pollution caused delayed gametogenesis and unsynchronized gamete release in two coral species, Acropora millepora and Acropora digitifera, from the Indo-Pacific Ocean. Given the urbanization along major coasts, light pollution could thus further threaten coral communities’ populations, which are already under severe degradation. A worldwide-modeled light pollution impact assessment is provided, which can help incorporate an important variable in coral reef conservation planning.
    Language: English
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  • 157
    Publication Date: 2021-02-04
    Description: The isotopic compositions of Li and B have great potential for the tracing of fluid sources and for the characterization of ore-forming processes. The fractionation of Li and B isotopes during the magmatic-hydrothermal transition in evolved granites, however, is not well understood as these rocks commonly show multiple late hydrothermal overprints. Tourmaline is sensitive to changes in melt and fluid compositions during its growth and resistant to alteration by later fluids, which makes it a good recorder of Li and B isotopic signatures and fractionation at late evolutionary stages of magmatic systems. To characterize the evolution of a Sn-ore forming granitic intrusion, we analyzed magmatic, hydrothermal, and detrital-sedimentary tourmaline from the Yuanbaoshan granite, associated cassiterite-tourmaline-quartz veins, and disseminated tourmaline-bearing cassiterite-sulfide ore in the sedimentary wall rocks. The Li and B isotopic compositions of tourmaline from these rocks do not covary, largely due to mineral-controlled decoupling during magmatic and hydrothermal processes. Because of the dominant role of tourmaline on the B budget of the rock, magmatic and hydrothermal tourmalines show little variation in δ11B (−12.5 to −8.2‰), a signature reflecting the metasedimentary protoliths of the melt. In contrast, several rock-forming minerals contribute to the budget of Li, which shows significant variation in δ7Li (−0.3 to +6.9‰). The isotopic fractionation of Li in tourmaline from rocks of the Yuanbaoshan area is controlled by three major processes: (i) fractional crystallization results in magmatic tourmaline having progressively higher δ7Li values and higher Li contents, (ii) the magmatic-hydrothermal transition leads to higher δ7Li values at lower Li contents in hydrothermal tourmaline, and (iii) extensive fluid-rock interaction adds isotopically light Li to hydrothermal tourmaline in the wall rocks. Extensive fluid-rock interaction also leached HREE, Mg, isotopically light B, and probably Sn from the granites and/or wall rocks. Tourmaline seems to robustly record progressive changes in Li isotopes in evolving magmatic-hydrothermal systems and hydrothermal mineral deposits.
    Language: English
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  • 158
    facet.materialart.
    Unknown
    In:  Eos, Transactions American Geophysical Union
    Publication Date: 2021-02-02
    Description: As part of an effort to develop a geothermal energy source beneath its campus, Cornell University is planning to probe the “boring” old continental crust upon which many people live.
    Language: English
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  • 159
    facet.materialart.
    Unknown
    In:  Glückauf-Mining-Reporter : international journal for mining, tunnelling, equipment and technology
    Publication Date: 2021-02-02
    Description: To limit global warming to 2 °C above pre-industrial levels, our society is confronted with the urgent need to make the transition to a globally sustainable energy system (1). Geothermal energy is available regardless of season or time and, unlike many other renewable energies, is therefore suitable for base-load sytems. Geothermal energy is regarded as renewable as heat flows back into the reservoir due to temperature conditions and transport processes. It uses the energy source from the earth’s interior, which is inexhaustible by human standards. Geothermal energy can play an important role in the decarbonization of the energy system in Germany. In Central Europe, the greatest geothermal potential lies in the crystalline basement with important hotspots in areas under tectonic tension. These include the Upper Rhine Graben as a rift zone with hydrothermal fluid flows and exceptional temperature anomalies in the deep underground (2). The technology “Enhanced Geothermal Systems” (EGS) was developed to exploit the geothermal potential in the crystalline (3). EGS use the deep fractured subsoil as a natural heat exchanger. With at least two boreholes, a thermal water cycle is created that brings geothermal energy to the surface and makes it usable (4). However, since relatively high flow rates (〉 10 l/s) are required for economic operation, the natural permeability of the rock in the crystalline – in contrast to hydrothermal systems – must be increased by hydraulic or chemical stimulation measures (reservoir engineering) to increase the flow rates. A major challenge for EGS is to control and minimize the induced seismicity generated in this process, both in the reservoir engineering and operation phase and with a view to increasing public acceptance. A profound understanding of the multi-physical processes in the reservoir, such as the complex interactions of the fluid with the reservoir at high flow rates, is indispensable for this. New scientifically based strategies and technologies are urgently needed to exploit the geothermal potential economically and at the same time in an environmentally compatible way.
    Language: English , German
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  • 160
    Publication Date: 2021-02-04
    Description: We are providing the geophysical data used to develop a gravity validated 3D lithospheric configuration of the Caribbean and north South American plates. The sources of these data are described in Section 4 of this README. Republication of subsets of these data are with permission of the authors or allowed by the licences of the input data. This data repository contains the lithospheric layers of the gravity validated 3D structural and density model of the Caribbean and north South American plates. In this model, the integration of different publicly available geophysical datasets was made, after an interpolation to a homogeneous spatial resolution of 25 km was performed. The data repository also contains the average density of the crystalline crust obtained after forward modelling the gravity anomalies. Additionally, the rotation files of the GPlates reconstructions of the Caribbean Large Igneous Plateau (CLIP) back to 90 Ma are included. This kinematic analysis was based on different reconstructions previously published by other authors. Further information and citations are given on the README file associated to this data repository.
    Language: English
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  • 161
    Publication Date: 2021-02-04
    Description: We report new in-situ U-Pb zircon ages which were obtained from a variety of lithologies within the Dete-Kamativi Inlier of western Zimbabwe using both LA-ICP-MS and SIMS. These include igneous or metamorphic zircon grains from granitoids and granitic gneisses as well as detrital zircon grains from a number of paragneisses. The oldest ages are from two highly deformed migmatitic granitoid orthogneisses, which yielded Neoarchaean concordia ages of 2723 Ma and 2694 Ma, which are interpreted to be crystallisation ages. These are the first Archaean ages from the Dete-Kamativi Inlier, indicating that the Archaean Zimbabwe Craton extends much farther west than previously recognised. Our new maximum ages of deposition of 2.31, 2.0 and 2.07 Ga for the Malaputese, Inyantue and Tshontanda Formations, respectively, match closely with previously determined maximum ages of 2.29, 2.07 and 2.16 Ga for the Deweras, Lomagundi and Piriwiri Groups, thus supporting the lithostratigraphic correlation of the Dete-Kamativi Inlier with the Magondi Supergroup. Foliated and unfoliated K-feldspar megacrystic granites and granodiorites have yielded concordia ages ranging from 2.08 to 2.01 Ga. They contain abundant Archaean inherited zircon grains ranging in age from 3.34 to 2.66 Ga, implying the involvement of Archaean crust in their petrogenesis. These results suggest the formation of a calc-alkaline continental magmatic arc on the western edge of the Archaean Zimbabwe Craton, some 80 Ma prior to the onset of the Palaeoproterozoic Magondi Orogeny.
    Language: English
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  • 162
    Publication Date: 2021-02-04
    Description: This dataset provides rheometric data of three viscous materials used for centrifuge experiments at the Tectonic Modelling Laboratory of CNR-IGG at the Earth Sciences Department of the University of Florence (Italy). The first material, PP45, is a mixture of a silicone (Polydimethylsiloxane or PDMS SGM36) and plasticine (Giotto Pongo). The PDMS is produced by Dow Corning and its characteristics are described by e.g. Rudolf et al. 2016a,b). Giotto Pongo is produced by FILA (Italy). Both components are mixed following a weight ratio of 100:45, and the final mixture has a density of 1520 kg m3. The second material, SCA705 is a mixture of Dow Corning 3179 putty, mixed with fine corundum sand and oleic acid with a weight ratio of 100:70:05 and a resulting density of 1660 kg m3. The final material, SCA7020 consists of the same components as SCA705, but with a slightly higher oleic acid content reflected in the weight ratio of 100:70:20. The mixture’s density is 1620 kg m3. The material samples have been analyzed in the Helmholtz Laboratory for Tectonic Modelling (HelTec) at GFZ German Research Centre for Geosciences in Potsdam using an Anton Paar Physica MCR 301 rheometer in a plate-plate configuration at room temperature (20˚C). Rotational (controlled shear rate) tests with shear rates varying from 10-4 to 1 s-1 were performed. Additional temperature tests were run with shear rates between 10-2 to 10-1 s-1 for a temperature range between 15 and 30˚C. According to our rheometric analysis, the materials all exhibit shear thinning behavior, with high power law exponents (n-number) for strain rates below 10-2s-1, while power law exponents are lower above that threshold.For PP45, the respective n-numbers are 4.8 and 2.6, for SCA705 6.7 and 1.5, and for SCA7020 9.1 and 2.0. The temperature tests show decreasing viscosities with increasing temperatures with rates of -3.8, -1.4 and -1.9% per ˚K for PP45, SCA705 and SCA7020, respectively. An application of the materials tested can be found in Zwaan et al. (2020).
    Language: English
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  • 163
    Publication Date: 2021-02-04
    Description: Magmatic volatiles can be considered as the surface fingerprint of active volcanic systems, both during periods of quiescent and eruptive volcanic activity. The spatial variability of gas emissions at Earth’s surface is a proxy for structural discontinuities in the subsurface of volcanic systems. We conducted extensive and regular spaced soil gas surveys within the Los Humeros geothermal field to improve the understanding of the structural control on fluid flow. Surveys at different scales were performed with the aim to identify areas of increased gas emissions on reservoir scale, their relation to unknown/knows volcano-tectonic structures on fault scale favoring fluid flow, and determine the origin of gas emissions. Herein, we show results from a carbon dioxide efflux scouting survey, which was performed across the main geothermal production zone together with soil temperature measurements. We identified five areas with increased carbon dioxide emissions, where further sampling was performed with denser sampling grids to understand the fault zone architecture and local variations in gas emissions. We show that a systematic sampling approach on reservoir scale is necessary for the identification and assessment of major permeable fault segments. The combined processing of CO2 efflux and carbon/helium isotopes facilitated the detection of permeable structural segments with a connection to the deep, high-temperature geothermal reservoir, also in areas with low to intermediate carbon dioxide emissions. The results of this study complement existing geophysical datasets and define further promising areas for future exploration activities in the north- and southwestern sector of the production field. The data are presented as one zip folder with 4 data tables (tab delimited text format) according to the measurement variable. The columns are defined in each data file.
    Language: English
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  • 164
    Publication Date: 2021-02-04
    Description: RomUkrSeis is a controlled source wide-angle reflection and refraction (WARR) profile acquired in August 2014. It is 675 km long, running roughly SW-NE from the Apuseni Mountains in Romania and the Transylvanian Basin, crossing the arc of the Eastern Carpathian orogen and terminating in the East European Craton (EEC) in SW Ukraine. Well-constrained 2-D ray-tracing P- and partly S-wave velocity models have been constructed along the profile from 348 single-component seismic recorders and eleven shot points. The Eastern Carpathian arc formed in the Cenozoic and have obscured the pre-existing Teisseyre-Tornquist Zone (TTZ), which is a transition zone between the Precambrian EEC and continental terranes accreted to it from the southwest in the Palaeozoic. The TTZ is characterised by low-velocity through its entire crust (6.0–6.3 km/s) and a considerable width (~140 km). It is interpreted as EEC crust stretched during rifting and continental margin formation in the Neoproterozoic and early Palaeozoic. The crust of the TTZ has a “trough in trough” structure wherein an upper body of ~40 km width comprising Outer Carpathian (Vp 4.9 km/s) and Late Palaeozoic-Mesozoic (Vp 5.4 km/s) units to 15 km depth lies above a wider, deeper one of inferred Neoproterozoic-early Palaeozoic strata. The crust of the Transylvanian Basin and Apuseni Mountains is relatively thin (~32 km). A high-velocity body at 4–12 km depth in this area is interpreted as a rootless fragment of an ophiolite complex exposed at the surface in this area. The lower crust beneath the Transylvanian Basin displays higher velocities than adjacent segments. Moho topography is strongly differentiated along the profile, varying from 32 to 50 km. The Moho shape, especially in the area between the Inner and Outer Carpathians, suggests a NE dip and, hence, thrusting of the Tisza-Dacia lowermost crustal and upper mantle units under the TTZ domain which, in turn, could be thrust under the cratonic (EEC) block.
    Language: English
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  • 165
    Publication Date: 2021-02-04
    Description: The Regional Research Network „Water in Central Asia“ (CAWa) funded by the German Federal Foreign Office consists of 19 remotely operated multi-parameter stations (ROMPS) in Central Asia. These stations were installed by the German Research Centre for Geosciences (GFZ) in Potsdam, Germany in close cooperation with the Central-Asian Institute for Applied Geosciences (CAIAG) in Bishkek, Kyrgyzstan, the national hydrometeorological services in Uzbekistan and Tajikistan, the Ulugh Beg Astronomical Institute in Tashkent, Uzbekistan, and the Kabul Polytechnic University, Afghanistan. The primary objective of these stations is to support the establishment of a reliable data basis of meteorological and hydrological data especially in remote areas with extreme climate conditions in Central Asia for applications in climate and water monitoring. Up to now, ten years of data are provided for an area of scarce station distribution and with limited open access data which can be used for a wide range of scientific or engineering applications. This dataset provides different types of raw hydrometeorological data such as air temperature, relative humidity, air pressure, wind speed and direction, precipitation, solar radiation, soil moisture and soil temperature as well as snow parameters and river discharge information for selected sites. The data has not undergone any quality control mechanism and should, therefore, be seen as raw data. A visual inspection of the data set has been made and some errors and quality degradation are listed in Zech et al. (2020) but does not claim to be complete. A quality control is strongly recommended by the authors before using the data. Each station data has its own storage directory at the data dissemination server named with the abbreviation (4-letter code) of the station. The data is sampled with a 5-minute interval and stored in hourly files separated by the type of data. These files are then archived as monthly files named with the station abbreviation, type of data, year and month. After one year, these monthly files are further archived to a yearly file. A detailed description for the stations is provided by the Station Exposure Descriptions. Further information about the dataset can be found in Zech et al. (2020). All data is compiled as ASCII data in two different formats which are explained in the documents GITW-SSP-FMT-GFZ-003.pdf (for the stations ALAI, ALA6, and SARY) and CAWA-SSP-FMT-GFZ-006.pdf (for all other stations). Monthly, the data will be dynamically extended as long as data can be acquired from the stations. Additionally, the near real-time data can be displayed and downloaded without any registration from the Sensor Data Storage System (SDSS) hosted at the Central-Asian Institute for Applied Geosciences (CAIAG) in Bishkek, Kyrgyzstan.
    Language: English
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  • 166
    Publication Date: 2021-02-04
    Description: This data publication includes detrital remanent magnetisation data of glacial sediments from the Arkhangelsky Ridge in the SE Black Sea. In order to test the acquisition of a detrital remanent magnetization (DRM) in glacial Black Sea sediments material from ca. 800 ml of diluted mud with a density of 1.3 gcm-3 was successively redeposited into seven plastic boxes under controlled magnetic field conditions. A two-component coil system was used to adjust the magnetic field in horizontal (H, equal to magnetic NS) and vertical (V) direction. Total field strength for each experiment with seven samples was varied between 1.72 and 114.21 µT (1st column of data sheet), mostly opposite to the ambient field in the laboratory. Compaction (partial drying) of the diluted mud was accomplished by evaporation of a fraction of the pore water. Sample boxes were sited on a wooden platform. Vibration of the platform, excited by an old computer fan with an imbalance hanging below the platform, was intended both to promote alignment of magnetic particles parallel to the field set by the coils and to force settling of the sediments during partial drying. The majority of the samples were treated this way, entry ‘vibr.’ in column ‘action’ of data sheet. A smaller portion of the samples were created on ‘still’ platform, that is, without vibration. Samples were treated the following way: Measurements of low-field magnetic susceptibility (k-bulk) were performed with an AGICO MFK-1S susceptibility meter. Measurements of the detritral remanent magnetization (DRM) and of the anhysteretic remanent magnetization (ARM) were performed with a 2G 755 SRM long-core cryogenic magnetometer. The ARM was imparted with a 2G660 single-axis alternating field (AF) demagnetizer using 100 mT alternating field and 50 µT static field. After ARM measurements, samples produced on vibrating platform also were imparted a ‘strong’ ARM (sARM) using 100 mT alternating field and 150 µT static field. DRM and (s)ARM both were stepwise demagnetized with the in-line 3-axes AF demagnetizer of the cryogenic magnetometer, applying steps of 0, 5, 10, 15, 20, 30, 40, 50, 65, 80, 100 mT AF peak amplitude. Iso-thermal remanent magnetizations (IRM) were imparted with a 2G 660 pulse magnetizer using 1500 mT for producing a saturation magnetization and -200 mT for remagnetization of the low-coercive fraction. Measurements were performed with a Molyneux spinner magnetometer. The data are provided as ASCII table and are described in Nowaczyk et al. (2020) and the associated data description file.
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  • 167
    Publication Date: 2021-02-04
    Description: Pollen are widespread and abundant microspores that are resistant against decay. Their frequent appearance in climate archives gives the opportunity to study vegetation cover changes and past environmental characteristics. Morphology-based pollen analysis focus on the taxonomic identification of pollen grains extracted out of sediment cores or other archives. The prime advantage of this approach is a worldwide applicability enabling temperature and precipitation reconstructions through quantitative methods. Stable isotope analysis is another approach using pollen in climate studies. Due to the immediate physiological responses of plants to environmental change, isotope values of pollen potentially provide high-resolution palaeoclimate information. Because this method for studying environmental changes is still in the need of a general assessment of its spectrum of applicability and limitations, this thesis focusses mainly on preliminary investigations of species-specific pollen-isotope variability and applicability in environmental studies. A case study of climate and vegetation reconstruction on the north-eastern Qinghai-Tibetan Plateau using classical morphology-based palynology is included in this dissertation as a first research topic. Pollen assemblages extracted out of the Daotang Pond record reveal environmental changes over the last 1200 years.The Medieval Warm Period occurred on the Qinghai-Tibetan Plateau between CE 850 and 1400. This climate anomaly was accompanied by regular East Asian Summer Monsoon penetrations and moisture input from the eastern lowland. Dry spells with diminished precipitation during the Medieval Warm Period are detectable out of the deposited pollen assemblages, but they have not been as severe as reported from other regions on the Qinghai-Tibetan Plateau. This is most likely caused by a humid micro-climate in the vicinity of the Qinghai Lake drainage basin. Features of the Little Ice Age (CE 1450 to 1950) can also be traced by analysing the pollen assemblages of the samples. Although the Little Ice Age is characterized by a weakened East Asian Summer Monsoon, the pollen record does not display a particularly dry environment during this time period, probably due to generally lower temperatures and diminished evapotranspiration. However, long distance transport of pollen is known to falsify pollen assemblages and its impact on the reconstruction of past environmental conditions cannot be ruled out. Additionally, the Qinghai-Tibetan Plateau is a pastoral region and its vegetation composition has been affected by grazing herds, diminishing the climate information which can be drawn from a quantitative morphology-based pollen analysis. The second part of this dissertation focusses on comprehensive investigations about species-specific isotope variability of modern pollen to promote the application of isotope analysis of fossil pollen in palaeoclimate reconstructions. Modern pollen of nine abundant tree species were sampled during the consecutive vegetation periods of 2015 and 2016 in seven national and nature parks in central and northern Europe. The investigation of various non-climate impact factors on the pollen-isotopes helps to assess sampling strategies in future studies and supports the interpretation of fossil pollen-isotope values. The results suggest that each species has specific δ13C and δ18O patterns and ranges within their pollen-isotope values and their spectra reveal gradients between maritime and continental study sites. The altitudinal effect, an increase in the isotope values with elevation, can be traced within the δ13C but not within the δ18O values of Picea abies pollen. The δ13Cpollen and δ18Opollen values of broad-leaved species flowering before leaf proliferation (January to March) were significantly lower than the isotope values of broad-leaved trees flowering later in spring (April to May). Pollen-isotope values of early flowering species are believed to reflect environmental conditions of the previous autumn and winter, whereas the isotope values of spring-flowering species reflect conditions of the ongoing season after the reoccurrence of growth. These findings indicate, that seasonal weather reconstructions using pollen-isotope values of different species are feasible. Pollen-isotope values of all species varied within the sampling sites. They even varied significantly between different flower positions on a tree and also within single branches. The circumferential variability within trees was up to 3.5‰ for δ13Cpollen and 2.1‰ for δ18Opollen. Species-specific pollen-isotope variation between the two consecutive years was on average 1.0‰ for δ13C and 1.6‰ for δ18O and oxygen pollen-isotopes even changed significantly during the last stages of pollen maturation. Regarding palaeoclimate investigations, these results emphasize the need for a taxonomic separation of fossil pollen and the analysis of a sufficient amount of pollen material to avoid interpretation errors due to outliers caused by flowering positions or an unusual origin of the pollen. A chemical purification protocol of modern and fossil pollen samples needs to be established to advance reproducibility of the analytical results when fossil pollen-isotopes are used to reconstruct climate conditions. Therefore, the impact of four chemicals on the δ13C and δ18O values of modern pollen sampled from eight abundant tree species were assessed and evaluated. The results suggested species-specific alterations of the pollen-isotope values. Potassium hydroxide, hydrofluoric acid and sodium hypochlorite alter the carbon and oxygen isotope values of pollen to an assessable degree and therefore their usage to purify pollen samples can be rated as unproblematic in future palaeoclimate studies. The application of sulfuric acid on the other hand should generally be avoided, because the chemical alters the δ13Cpollen and δ18Opollen values with a highly variable offset. The outcome of the comprehensive research on pollen-isotope variability and influencing factors is a contribution towards a regular usage of stable isotope analysis of pollen in palaeoecological investigations. Open research questions on the topic of amplifying pollenisotope analysis in palaeoclimate research remain. An actual application of the method requires additional analytical tests, in particular an improved separation technique to extract fossil pollen using a minimal amount of chemicals. Also, the determination of important climatological impact factors defining the carbon and oxygen isotope values of pollen is necessary. The possibility to use multiple approaches of fossil pollen to reconstruct climate conditions of the past is valuable and worthy of further intensive investigations. Pollen sind weit verbreitete, zahlreich vorhandene und sehr resistente Mikrosporen. Ihr häufiges Auftreten in Klimaarchiven bietet die Möglichkeit, Veränderungen der Vegetationsdecke und vergangene Umweltmerkmale zu untersuchen. Morphologie-basierte Pollenanalysen konzentrieren sich auf die taxonomische Identifizierung von Pollenkörnern, die aus Sedimentbohrkernen oder anderen Archiven extrahiert wurden. Der Hauptvorteil dieses Ansatzes ist eine weltweite Anwendbarkeit, die verlässliche Temperatur- und Niederschlagsrekonstruktionen durch etablierte quantitative Methoden ermöglicht. Die Analyse stabiler Isotope ist ein weiterer Ansatz, bei dem Pollen in Klimastudien verwendet werden können. Aufgrund der unmittelbaren physiologischen Reaktionen von Pflanzen auf Umweltveränderungen können Isotopenwerte von Pollen hochauflösende Paläoklimainformationen liefern. Da diese neuere Methode zur Untersuchung von Umweltveränderungen noch einer generellen Einschätzung ihres Anwendungsspektrums und ihrer Grenzen bedarf, konzentriert sich diese Arbeit hauptsächlich auf Voruntersuchungen zur artspezifischen Pollenisotopenvariabilität und Anwendbarkeit in Umweltstudien. Eine Fallstudie zur Klima- und Vegetationsrekonstruktion auf dem Qinghai-Tibetischen Plateau unter Verwendung der klassischen Morphologie-basierten Palynologie ist als erstes Forschungsthema in dieser Dissertation enthalten. Die wechselnde Zusammensetzung der Pollentypen, die aus den Proben des Daotang Ponds extrahiert wurden, zeigen die Umweltveränderungen der letzten 1200 Jahre auf dem nord-östlichen Qinghai-Tibetischen Plateau. Die mittelalterliche Warmzeit fand in der Region zwischen 850 und 1400 n. Chr. statt. Diese Klimaanomalie ist am Daotang Pond gekennzeichnet von regelmäßigen Einbrüchen des ostasiatischen Sommermonsuns und Feuchtigkeitseinträgen aus dem östlichen Tiefland. Trockenperioden mit vermindertem Niederschlag während des mittelalterlichen Klimaoptimums sind aus den abgelagerten Pollenansammlungen nachweisbar, aber sie waren nicht so schwerwiegend wie in anderen Regionen auf dem Qinghai-Tibetischen Plateau, was vermutlich auf ein bestehendes feuchtes Mikroklima durch den nahegelegenen Qinghai See zurückzuführen ist. Die Kleine Eiszeit (1450 bis 1950 n. Chr.) kannauch durch die Morphologie-basierte Analyse der Pollenansammlungen in den Daotang Proben zurückverfolgt werden. Obwohl die Kleine Eiszeit durch einen abgeschwächten ostasiatischen Sommermonsun gekennzeichnet ist, zeigt der Pollenflug in diesem Zeitraum keine besonders trockene Umgebung. Vermutlich war in der Region aufgrund allgemein niedrigerer Temperaturen auch die Evapotranspiration deutlich vermindert. Es ist jedoch bekannt, dass der Langstreckentransport von Pollen die Pollenansammlungen verfälscht, und sein Einfluss auf die Rekonstruktion vergangener Umweltbedingungen kann nicht ausgeschlossen werden. Darüber hinaus ist das Qinghai-Tibetische Plateau eine Hirtenregion und die Vegetationszusammensetzung wurde stark durch weidende Herden beeinträchtigt, wodurch die Klimainformationen, die aus einer quantitativen Morphologie-basierten Pollenanalyse gewonnen werden können, vermindert sind. Der zweite Teil dieser Dissertation konzentriert sich auf umfassende Untersuchungen zur artspezifischen Isotopenvariabilität moderner Pollen, um die Anwendung der Isotopenanalyse fossiler Pollen bei Paläoklima-Rekonstruktionen zu fördern. In sieben National und Naturparks in Mittel- und Nordeuropa wurden während zwei aufeinanderfolgender Vegetationsperioden 2015 und 2016 moderne Pollen von neun weit verbreiteten Baumarten beprobt. Die Untersuchung verschiedener nicht-klimatischer Einflussfaktoren auf die Pollenisotope hilft bei der Beurteilung von Beprobungsstrategien in zukünftigen Studien und unterstützt die Interpretation der Isotopenwerte fossiler Pollen. Die Ergebnisse deuten darauf hin, dass jede Art spezifische 13C- und 18O-Muster und Spannweiten innerhalb ihrer Pollenisotopenwerte aufweist und ihre Spektren zeigen Gradienten zwischen maritimen und kontinentalen Untersuchungsgebieten. Der Höheneffekt, eine Zunahme der Isotopenwerte mit der Höhe über NN, kann innerhalb der δ13C-, aber nicht innerhalb der δ18O-Werte von Picea abies Pollen nachgewiesen werden. Die δ13Cpollen- und δ18Opollen-Werte von Laubbaumarten, die vor dem Blattaustrieb blühten (Januar bis März), waren signifikant niedriger als die Isotopenwerte von Laubbäumen, die später im Frühjahr blühen (April bis Mai). Man geht davon aus, dass die Pollenisotopenwerte früh blühender Arten die Umweltbedingungen des vorangegangenen Herbstes und Winters widerspiegeln, während die Isotopenwerte anderer Arten die Bedingungen der laufenden Saison nach dem Wiederauftreten des Wachstums aufzeigen. Diese Ergebnisse deuten darauf hin, dass saisonale Wetterrekonstruktionen mit den Pollenisotopenwerten verschiedener Arten durchführbar sind. Die Pollenisotopenwerte aller Arten variierten innerhalb der Sammelorte, und sie variierten auch signifikant zwischen verschiedenen Blütenpositionen an einem Baum und sogar innerhalb eines einzelnen Zweiges. Die zirkumferentielle Variabilität betrug bis zu 3.5‰ für δ13Cpollen und 2.1‰ für δ18Opollen. Die artenspezifische Pollenisotopenvariation zwischen den beiden aufeinanderfolgenden Jahren betrug durchschnittlich 1.0‰ für δ13C und 1.6‰ für δ18O und die Sauerstoffisotopenwerte änderten sich sogar signifikant während der letzten Stadien der Pollenreifung in der Blüte. Im Hinblick auf paläoklimatische Untersuchungen unterstreichen diese Ergebnisse die Notwendigkeit einer taxonomischen Trennung fossiler Pollen und der Analyse einer ausreichenden Menge an Pollenmaterial, um Interpretationsfehler als Folge von Ausreißern aufgrund der Blühposition oder einer ungewöhnlichen Herkunft der Pollen zu vermeiden. Ein standardisiertes chemisches Aufbereitungsprotokoll für moderne und fossile Pollenproben ist notwendig um die Reproduzierbarkeit der analytischen Ergebnisse zu verbessern, wenn fossile Pollenisotope zur Rekonstruktion der Klimabedingungen verwendet werden. Daher wurden die Auswirkungen von vier Chemikalien auf die δ13C- und δ18O-Werte moderner Pollenproben von acht häufig vorkommenden Baumarten untersucht und bewertet. Die Ergebnisse deuteten auf artspezifische und substanzspezifische Veränderungen der Pollenisotopenwerte hin. Kaliumhydroxid, Flusssäure und Natriumhypochlorit verändern die Kohlenstoff- und Sauerstoffisotopenwerte von Pollen in einem abschätzbaren Maße, sodass ihre Verwendung zur Aufbereitung von Pollenproben in zukünftigen Paläoklimastudien als unproblematisch eingestuft werden kann. Der Einsatz von Schwefelsäure hingegen sollte generell vermieden werden, da die Chemikalie die δ13Cpollen- und δ18Opollen-Werte mit einem sehr variablen Offset verändert. Das Ergebnis der umfangreichen Forschung zur Pollen-Isotopenvariabilität und zu deren Einflussfaktoren ist ein Beitrag zu der zukünftigen etablierten Anwendung der stabilen Isotopenanalyse von Pollen in paläoökologischen Untersuchungen. Offene Forschungsfragen zur Pollenisotopenanalyse in der Paläoklimaforschung bleiben bestehen. Eine tatsächliche Anwendung der Methode erfordert zusätzliche analytische Tests, insbesondere eine verbesserte Trenntechnik zur Extraktion fossiler Pollen mit einem minimalen Chemikalieneinsatz. Auch die Bestimmung wichtiger klimatologischer Einflussfaktoren, die die Kohlenstoff- und Sauerstoffisotopenwerte von Pollen definieren, ist notwendig. Die Möglichkeit, mehrere Methoden zur Analyse fossiler Pollen für eine Rekonstruktion von Klimabedingungen anwenden zu können, ist wertvoll. Daher verdient das Vorranbringen der Pollenisotopie-Methode weitere intensive Untersuchungen.
    Description: Pollen sind weit verbreitete, zahlreich vorhandene und sehr resistente Mikrosporen. Ihr häufiges Auftreten in Klimaarchiven bietet die Möglichkeit, Veränderungen der Vegetationsdecke und vergangene Umweltmerkmale zu untersuchen. Morphologie-basierte Pollenanalysen konzentrieren sich auf die taxonomische Identifizierung von Pollenkörnern, die aus Sedimentbohrkernen oder anderen Archiven extrahiert wurden. Der Hauptvorteil dieses Ansatzes ist eine weltweite Anwendbarkeit, die verlässliche Temperatur- und Niederschlagsrekonstruktionen durch etablierte quantitative Methoden ermöglicht. Die Analyse stabiler Isotope ist ein weiterer Ansatz, bei dem Pollen in Klimastudien verwendet werden können. Aufgrund der unmittelbaren physiologischen Reaktionen von Pflanzen auf Umweltveränderungen können Isotopenwerte von Pollen hochauflösende Paläoklimainformationen liefern. Da diese neuere Methode zur Untersuchung von Umweltveränderungen noch einer generellen Einschätzung ihres Anwendungsspektrums und ihrer Grenzen bedarf, konzentriert sich diese Arbeit hauptsächlich auf Voruntersuchungen zur artspezifischen Pollenisotopenvariabilität und Anwendbarkeit in Umweltstudien. Eine Fallstudie zur Klima- und Vegetationsrekonstruktion auf dem Qinghai-Tibetischen Plateau unter Verwendung der klassischen Morphologie-basierten Palynologie ist als erstes Forschungsthema in dieser Dissertation enthalten. Die wechselnde Zusammensetzung der Pollentypen, die aus den Proben des Daotang Ponds extrahiert wurden, zeigen die Umweltveränderungen der letzten 1200 Jahre auf dem nord-östlichen Qinghai-Tibetischen Plateau. Die mittelalterliche Warmzeit fand in der Region zwischen 850 und 1400 n. Chr. statt. Diese Klimaanomalie ist am Daotang Pond gekennzeichnet von regelmäßigen Einbrüchen des ostasiatischen Sommermonsuns und Feuchtigkeitseinträgen aus dem östlichen Tiefland. Trockenperioden mit vermindertem Niederschlag während des mittelalterlichen Klimaoptimums sind aus den abgelagerten Pollenansammlungen nachweisbar, aber sie waren nicht so schwerwiegend wie in anderen Regionen auf dem Qinghai-Tibetischen Plateau, was vermutlich auf ein bestehendes feuchtes Mikroklima durch den nahegelegenen Qinghai See zurückzuführen ist. Die Kleine Eiszeit (1450 bis 1950 n. Chr.) kannauch durch die Morphologie-basierte Analyse der Pollenansammlungen in den Daotang Proben zurückverfolgt werden. Obwohl die Kleine Eiszeit durch einen abgeschwächten ostasiatischen Sommermonsun gekennzeichnet ist, zeigt der Pollenflug in diesem Zeitraum keine besonders trockene Umgebung. Vermutlich war in der Region aufgrund allgemein niedrigerer Temperaturen auch die Evapotranspiration deutlich vermindert. Es ist jedoch bekannt, dass der Langstreckentransport von Pollen die Pollenansammlungen verfälscht, und sein Einfluss auf die Rekonstruktion vergangener Umweltbedingungen kann nicht ausgeschlossen werden. Darüber hinaus ist das Qinghai-Tibetische Plateau eine Hirtenregion und die Vegetationszusammensetzung wurde stark durch weidende Herden beeinträchtigt, wodurch die Klimainformationen, die aus einer quantitativen Morphologie-basierten Pollenanalyse gewonnen werden können, vermindert sind. Der zweite Teil dieser Dissertation konzentriert sich auf umfassende Untersuchungen zur artspezifischen Isotopenvariabilität moderner Pollen, um die Anwendung der Isotopenanalyse fossiler Pollen bei Paläoklima-Rekonstruktionen zu fördern. In sieben National und Naturparks in Mittel- und Nordeuropa wurden während zwei aufeinanderfolgender Vegetationsperioden 2015 und 2016 moderne Pollen von neun weit verbreiteten Baumarten beprobt. Die Untersuchung verschiedener nicht-klimatischer Einflussfaktoren auf die Pollenisotope hilft bei der Beurteilung von Beprobungsstrategien in zukünftigen Studien und unterstützt die Interpretation der Isotopenwerte fossiler Pollen. Die Ergebnisse deuten darauf hin, dass jede Art spezifische 13C- und 18O-Muster und Spannweiten innerhalb ihrer Pollenisotopenwerte aufweist und ihre Spektren zeigen Gradienten zwischen maritimen und kontinentalen Untersuchungsgebieten. Der Höheneffekt, eine Zunahme der Isotopenwerte mit der Höhe über NN, kann innerhalb der δ13C-, aber nicht innerhalb der δ18O-Werte von Picea abies Pollen nachgewiesen werden. Die δ13Cpollen- und δ18Opollen-Werte von Laubbaumarten, die vor dem Blattaustrieb blühten (Januar bis März), waren signifikant niedriger als die Isotopenwerte von Laubbäumen, die später im Frühjahr blühen (April bis Mai). Man geht davon aus, dass die Pollenisotopenwerte früh blühender Arten die Umweltbedingungen des vorangegangenen Herbstes und Winters widerspiegeln, während die Isotopenwerte anderer Arten die Bedingungen der laufenden Saison nach dem Wiederauftreten des Wachstums aufzeigen. Diese Ergebnisse deuten darauf hin, dass saisonale Wetterrekonstruktionen mit den Pollenisotopenwerten verschiedener Arten durchführbar sind. Die Pollenisotopenwerte aller Arten variierten innerhalb der Sammelorte, und sie variierten auch signifikant zwischen verschiedenen Blütenpositionen an einem Baum und sogar innerhalb eines einzelnen Zweiges. Die zirkumferentielle Variabilität betrug bis zu 3.5‰ für δ13Cpollen und 2.1‰ für δ18Opollen. Die artenspezifische Pollenisotopenvariation zwischen den beiden aufeinanderfolgenden Jahren betrug durchschnittlich 1.0‰ für δ13C und 1.6‰ für δ18O und die Sauerstoffisotopenwerte änderten sich sogar signifikant während der letzten Stadien der Pollenreifung in der Blüte. Im Hinblick auf paläoklimatische Untersuchungen unterstreichen diese Ergebnisse die Notwendigkeit einer taxonomischen Trennung fossiler Pollen und der Analyse einer ausreichenden Menge an Pollenmaterial, um Interpretationsfehler als Folge von Ausreißern aufgrund der Blühposition oder einer ungewöhnlichen Herkunft der Pollen zu vermeiden. Ein standardisiertes chemisches Aufbereitungsprotokoll für moderne und fossile Pollenproben ist notwendig um die Reproduzierbarkeit der analytischen Ergebnisse zu verbessern, wenn fossile Pollenisotope zur Rekonstruktion der Klimabedingungen verwendet werden. Daher wurden die Auswirkungen von vier Chemikalien auf die δ13C- und δ18O-Werte moderner Pollenproben von acht häufig vorkommenden Baumarten untersucht und bewertet. Die Ergebnisse deuteten auf artspezifische und substanzspezifische Veränderungen der Pollenisotopenwerte hin. Kaliumhydroxid, Flusssäure und Natriumhypochlorit verändern die Kohlenstoff- und Sauerstoffisotopenwerte von Pollen in einem abschätzbaren Maße, sodass ihre Verwendung zur Aufbereitung von Pollenproben in zukünftigen Paläoklimastudien als unproblematisch eingestuft werden kann. Der Einsatz von Schwefelsäure hingegen sollte generell vermieden werden, da die Chemikalie die δ13Cpollen- und δ18Opollen-Werte mit einem sehr variablen Offset verändert. Das Ergebnis der umfangreichen Forschung zur Pollen-Isotopenvariabilität und zu deren Einflussfaktoren ist ein Beitrag zu der zukünftigen etablierten Anwendung der stabilen Isotopenanalyse von Pollen in paläoökologischen Untersuchungen. Offene Forschungsfragen zur Pollenisotopenanalyse in der Paläoklimaforschung bleiben bestehen. Eine tatsächliche Anwendung der Methode erfordert zusätzliche analytische Tests, insbesondere eine verbesserte Trenntechnik zur Extraktion fossiler Pollen mit einem minimalen Chemikalieneinsatz. Auch die Bestimmung wichtiger klimatologischer Einflussfaktoren, die die Kohlenstoff- und Sauerstoffisotopenwerte von Pollen definieren, ist notwendig. Die Möglichkeit, mehrere Methoden zur Analyse fossiler Pollen für eine Rekonstruktion von Klimabedingungen anwenden zu können, ist wertvoll. Daher verdient das Vorranbringen der Pollenisotopie-Methode weitere intensive Untersuchungen.
    Language: English
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  • 168
    Publication Date: 2021-02-05
    Language: English
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  • 169
    Publication Date: 2021-02-04
    Description: The Highland Valley Copper porphyry Cu (±Mo) district is hosted in the Late Triassic Guichon Creek batholith in the Canadian Cordillera. Fracture-controlled sodic-calcic alteration is important because it forms a large footprint (34 km2) outside of the porphyry Cu centers. This alteration consists of epidote ± actinolite ± tourmaline veins with halos of K-feldspar–destructive albite (1–20 XAn) ± fine-grained white mica ± epidote. The distribution of sodic-calcic alteration is strongly influenced by near-orthogonal NE- and SE-trending fracture sets and by proximity to granodiorite stocks and porphyry dikes. Multiple stages of sodic-calcic alteration occurred in the district, which both pre- and postdate Cu mineralization at the porphyry centers. The mineral assemblages and chemical composition of alteration minerals suggest that the fluid that caused sodic-calcic alteration in the Guichon Creek batholith was Cl bearing, at near-neutral pH, and oxidized, and had high activities of Na, Ca, and Mg relative to propylitic and fresh-rock assemblages. The metasomatic exchange of K for Na, localized removal of Fe and Cu, and a paucity of secondary quartz suggest that the fluid was thermally prograding in response to magmatic heating. Calculated δ18Ofluid and δDfluid values of mineral pairs in isotopic equilibrium from the sodic-calcic veins and alteration range from 4 to 8‰ and −20 to −9‰, respectively, which contrasts with the whole-rock values for least altered magmatic host rocks (δ18O = 6.4–9.4‰ and δD = −99 to −75‰). The whole-rock values are suggested to reflect residual magma values after D loss by magma degassing, while the range of hydrothermal minerals requires a mixed-fluid origin with a contribution of magmatic water and an external water source. The O-H isotope results favor seawater as the source but could also reflect the ingress of Late Triassic meteoric water. The 87Sr/86Srinital values of strongly Na-Ca–altered rocks range from 0.703416 to 0.703508, which is only slightly higher than the values of fresh and potassic-altered rocks. Modeling of those data suggests the Sr is derived predominantly from a magmatic source, but the system may contain up to 3% seawater Sr. Supporting evidence for a seawater-derived fluid entrained in the porphyry Cu systems comes from boron isotope data. The calculated tourmaline δ11Bfluid values from the sodic-calcic domains reach 18.3‰, which is consistent with a seawater-derived fluid source. Lower tourmaline δ11Bfluid values from the other alteration facies (4–10‰) suggest mixing between magmatic and seawater-derived fluids in and around the porphyry centers. These results imply that seawater-derived fluids can infiltrate batholiths and porphyry systems at deep levels (4–5 km) in the crust. Sodic ± calcic alteration may be more common in rocks peripheral to porphyry Cu systems hosted in island-arc terranes and submarine rocks than currently recognized.
    Language: English
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  • 170
    Publication Date: 2021-02-04
    Description: In eastern Hesse and western Thuringia, Germany hosts significant potassium-bearing salt deposits industrially excavated in the Werra-Fulda mining district. The salt belongs to the upper Permian (Zechstein) and was deposited around 258 to 252.5 Ma ago. In the Werra-Fulda mining district, the halite rocks (Werra-Rocksalt, z1NA) contain two minable potash seams, potash Seam Thüringen (z1KTh) and potash Seam Hessen (z1KHe), with an average thickness between 2 m and 3 m (Figure 1). To investigate the chemical and isotopic composition of the gas phase of Seam Hessen, gaseous samples were collected from five, 2-meter deep, horizontal boreholes drilled in the potash horizon which is mined at a depth of 540 m. About 4 weeks in advance of the gas sampling, the packer-closed boreholes were evacuated to about 3kPa and the pressure gradient inside the holes was continuously monitored in the boreholes D1 to D5. Selected gas samples were analyzed for their noble gas isotopic composition and the δ13C values of CO2 and CH4. The noble gas isotopic compositions were determined using a VG 5400 noble gas mass spectrometer after purification in a preparation line. The carbon isotope compositions were analysed with a GC-IRMS, comprising a GC 6890N connected to a GC-C/TC III combustion device and coupled to a MAT 253 mass spectrometer. The standard deviation of the δ13C values (in ‰ vs. VPDB) is ± 0.5 ‰.
    Language: English
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  • 171
    Publication Date: 2021-02-04
    Description: The Proterozoic Carpentaria province in northern Australia comprises several of the wordl's largest Zn-Pb massive sulphide deposits. These deposits are mostly hosted in fine grained siliciclastic sedimentary rocks, which have been affected by variable degrees of tectonic overprint, especially to the south of the district. Three of these world class clastic-dominated (CD-type) Zn-Pb deposits (George Fisher, Hilton, and Mount Isa) are hosted in siltstones and mudstones of the Urquhart Shale Formation (ca. 1654 Ma; southern Carpentaria Province). The hydrothermal alteration footprint of these CD-type systems is not well constrained, which complicates exploration for and discovery of new CD-type Zn-Pb deposits. A major caveat to understanding such footprints is the availability of suitable correlative host rock lithologies, which represent the un-mineralized protolith (background composition). In this study, we report whole rock lithogeocheochemical and mineralogical data from drill-holes that intersected the main ore bodies at the George Fisher deposit and from correlative un-mineralized Urquhart Shale. These data were combined with petrographic observations in order to (1) establish the detrital, authigenic, and diagenetic background composition of the Paleoproterozoic Urquhart Shale Formation, and to (2) evaluate mineralogical and associated chemical mass changes that resulted from the hydrothermal event(s) at the George Fisher deposit. This data report includes bulk rock major, minor, and trace element composition, as well as S, TOC, total C, CO2, Cgra concentrations, and mineralogical composition of 41 samples from the un-mineralized Urquhart Shale Formation and 70 samples from the George Fisher deposit. The data were generated using X-ray fluorescence, inductively coupled plasma mass spectrometry, LECO, and X-ray diffraction analyses. Access to drill cores was granted by Mount Isa Mines (MIM) George Fisher operation and Mount Isa Mines Resource Development; the respective MIM drill core IDs and depths of individual samples are reported in the data table. For further details see: Rieger et al. (2020 - WHEN AVAILABLE)
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  • 172
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR - Data | GIPP Experiment and Data Archive
    Publication Date: 2021-02-09
    Description: The FOSA (FOgo Seismic Array) project has been carried out from October 2015 to December 2016 to investigate the seismicity of Fogo volcano after its eruption in 2014/2015. Fogo is the only volcano of the Cape Verde archipelago with reported historic eruptions. The eruptions occur frequently with an interval of about 20 years. However, the structure and extent of the related volcanic plumbing system are not well understood. The focus of the FOSA project was on the detection of ongoing magmatic activity and information about the plumbing system, using seismic array techniques. The array of the FOSA study was operated from October 2015 to December 2016, close to the village Achada Furna. From January 2016 we complemented the network with three additional broadband stations for an improved event detection and localization.
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  • 173
    Publication Date: 2021-02-08
    Description: Experimental and epidemiologic studies suggest that light at night (LAN) exposure disrupts circadian rhythm, and this disruption may increase breast cancer risk. We investigated the potential association between residential outdoor LAN and breast cancer risk. A population-based case–control study was conducted in Vancouver, British Columbia and Kingston, Ontario, Canada with incident breast cancer cases, and controls frequency matched by age in the same region. This analysis was restricted to 844 cases and 905 controls who provided lifetime residential histories. Using time-weighted average duration at each home 5–20 years prior to study entry, two measures of cumulative average outdoor LAN were calculated using two satellite data sources. Logistic regression was used to estimate the relationship between outdoor LAN and breast cancer risk, considering interactions for menopausal status and night shift work. We found no association between residential outdoor LAN and breast cancer for either measure of LAN [OR comparing highest vs. lowest tertile (DNB) = 0.95, 95% CI 0.70–1.27]. We also found no association when considering interactions for menopausal status and past/current night work status. These findings were robust to changes to years of residential data considered, residential mobility, and longer exposure windows. Our findings are consistent with studies reporting that outdoor LAN has a small effect or no effect on breast cancer risk.
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  • 174
    Publication Date: 2021-02-13
    Description: This dataset comprises numerical outputs from the thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) simulations described in the article "Modeling of planetary wave influences on the pre-reversal enhancement of the equatorial F region vertical plasma drift" (Yamazaki & Diéval, 2021).
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  • 175
    Publication Date: 2021-02-13
    Description: This dataset resulted from a parallel monitoring at two lakes, Lake Tiefer See (near Klocksin, TSK; 53° 35.5’ N, 12° 31.8’ E; 62 masl; N Germany) and Lake Czechowskie (Jezioro Czechowskie, JC; 53° 52.4’ N, 18° 14.3’ E; 108 masl; N Poland), and includes four different type of data for both locations: (i) sediment cores microfacies data, (ii) sediment fluxes and composition, (iii) selected water column data, and (iv) selected meteorological information obtained on site. This dual lake monitoring set-up was established in 2012 with the aim to investigate seasonal sedimentation and varve forming processes in detail. The datasets are provided in individual *.csv files, per type of data and per lake. The thin section data from surface sediment cores comprises the thicknesses of the most recent calcite varves’ sub-layers: spring diatom sub-layer, summer calcite sub-layer, and autumn/winter re-suspension sub-layer. The sediment flux data was obtained from sediment traps located in different water depths (epi- and hypolimnion), and the sediment composition is given by the fluxes of total organic carbon (TOC), calcium carbonate (as calculated from total inorganic carbon; TIC), and diatoms & inorganic matter. The water column data comprises water temperature from stationary loggers, and dissolved oxygen measured in ~ 1 meter depth-resolution. The meteorological data includes daily averages of air temperature and mean wind-speed, and summed daily rainfall. Further details about the sampling and analytical methods, data acquisition, and processing are given in Roeser et al. (2021; http://doi.org/10.1111/bor.12506).
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  • 176
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR - Data
    Publication Date: 2021-02-09
    Description: The KISS network was installed in the frame of the “Klyuchevskoy Investigation - Seismic Structure of an extraordinary volcanic system” project and recorded data between summer 2015 and summer 2016 in one of the world’s largest clusters of subduction volcanoes - the Klyuchevskoy volcanic group (KVG). It is located in eastern Russia at the northern end of the Kuril-Kamchatka subduction zone close to its intersection with the Aleutian arc and the north-western termination of Hawaii-Emperor seamount chain. Additional to the 4700m high Mount Klyuchevskoy the KVG contains 12 other volcanoes that have together erupted about 1 cubic meter rock per second averaged over the past 10,000 years. Among those Klyuchevskoy, Bezymianny and Tolbachik were the most active ones during the last decades with eruptions styles ranging from explosive to Hawaiian-type. The KISS experiment is designed to investigate the volcanic and seismic processes and its structural setting in the KVG. The network covers a circular region of about 80km diameter with some linear extensions. It includes data from 77 temporary seismic stations with broadband and short period sensors that were installed on concrete plates in about 60cm deep holes. Due to the local conditions the stations were battery powered and could not be serviced during the experiment. GPS reception of the digitizers was not continuous at all stations due to thick snow cover and vegetation. Waveform data are available from the GEOFON data centre, under network code X9, and are embargoed until end of 2019.
    Language: English
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  • 177
    Publication Date: 2021-02-17
    Description: Die Industrialisierung der Nordhemisphäre führte zur Verschmutzung und Erwärmung natürlicher Ökosysteme. Bei vielen abgelegenen sibirischen Seen lassen sich weitgehende Folgen für ihre Rollen als Süßwasserressourcen und ökologische Refugien feststellen.
    Description: Industrialisation in the Northern Hemisphere has led to the pollution and warming of natural ecosystems. Remote Siberian lakes are now under threat and face big environmental challenges that could have far-reaching consequences for freshwater resources and ecological refuges.
    Language: German , English
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  • 178
    Publication Date: 2021-02-05
    Description: Primary and secondary microseism originating in the world oceans and peaking at around 14 and 7 s, respectively, characterize the Earth's background noise in that frequency range. Microseism generated in marginal seas with partly shorter periods and higher spatial and temporal variability is less studied and requires stations in immediate proximity to the source to be observed. Such studies can help to elucidate the exact microseism generation areas and mechanisms in a constrained area. We analyze 15 years of broadband data recorded at the seismic station on Helgoland island in the marginal North Sea. In addition to remote primary (RPM) and secondary microseism (RSM) originating in the North Atlantic, we observe strong and dominant local secondary microseism (LSM) with on average higher frequencies above 0.2 Hz, in accordance with shorter wave periods of about 4–8 s in the shallow North Sea. During times with low RSM activity we observe local primary microseism (LPM) at frequencies in agreement with local ocean wave periods. The higher horizontal to vertical (H/V) ratio of LPM with respect to LSM indicates a major non‐Rayleigh wave contribution. LSM and LPM show a strong modulation with local semidiurnal ocean tides and microseism energy maxima preceding the water level maximum by 2.5 and 1.5 hr, respectively. This time shift might be influenced by stronger currents during rising than falling tides. Active sources of tide‐modulated microseism migrate along the North Sea coast in sync with the ocean tidal signal as evidenced by comparison of LSM maxima at stations distributed along the coast.
    Language: English
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  • 179
    Publication Date: 2021-03-08
    Language: English
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  • 180
    Publication Date: 2021-03-08
    Language: English
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  • 181
    Publication Date: 2021-03-16
    Description: Cerro Overo maar and La Albóndiga lava dome are two independent monogenetic volcanoes located in the Central Volcanic Zone of the Andes in northern Chile, close to the active Lascar and Chiliques volcanoes. Cerro Overo maar was formed 〈77 ka ago by explosive-effusive eruptions, including phreatomagmatic activity, while La Albóndiga lava dome (Pleistocene) is the result of magmatic explosive-effusive activity alone. Cerro Overo and La Albóndiga are characterized by deposits composed of pyroclastic rocks and dense coherent lava blocks. At Cerro Overo, these deposits are located around the crater rim, while at La Albóndiga, they form coherent in situ lava dome features. Cerro Overo also displays thin ash- and lapilli-dominated deposit layers presumed to be pyroclastic surge deposits, which include juvenile pyroclasts exhibiting cauliflower textures, numerous exotic accidental lithics, and ballistically transported lapilli, bombs, blocks, and bomb sags. These fragments include recycled, juvenile pyroclasts, as well as material from older volcanic and intrusive rocks from the stratigraphic units immediately below. These small-volume volcanoes represent two of the less silicic volcanoes (~54 wt.% SiO2) in the northern Chilean Pleistocene to Holocene volcanic provinces. They are characterized by a fine grain size (mainly fine lapilli), olivine phenocrysts with skeletal textures, ignimbritic, dioritic, and granitic xenoliths, and quartz xenocrysts, with high concentrations of incompatible trace elements and light rare earth elements. The general magmatic evolution of the Cerro Overo and La Albóndiga systems has been controlled by fast ascent (e.g., skeletal olivine phenocrysts) of mantle-derived magma associated with mixing, fractional crystallization, and a low degree of crustal assimilation during turbulent ascent processes. Such eruptions provide evidence that various factors play an essential role in the transition from explosive-effusive magmatic (Cerro Overo and La Albóndiga) to phreatomagmatic (Cerro Overo) volcanic eruption styles.
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  • 182
    Publication Date: 2021-02-28
    Description: The GRACE (Gravity Recovery and Climate Experiment) satellites, which comprises two spacecraft, GRACE-A and GRACE-B, were launched on 17 March 2002 into a near-circular, polar (inclination = 89◦ ) orbit with an initial altitude of about 490 km. The two satellites follow each other at a distance of about 200 km. The primary objective of the GRACE mission is to provide global high-resolution models of the Earth’s gravity field. The instruments supporting our study are the K-Band Ranging System (KBR), and the GPS Space Receiver (GPS). The K-Band Ranging System (KBR) system is the key science instrument of GRACE which measures the dual one-way range change between both satellites with a precision of about 1 μm per second. From the KBR1B data we can get the change of Total Electron Content (TEC). In addition the GPS Navigation Data (GNV1B) can provide us the position of the two satellites. From these data we can derive the average electron density between the two satellites. The data are stored as daily ASCII files using the file naming convention 'KBRNE_YYYY_MM_DD.dat'. Headers in each data file contain a short name for each column. A more detailed description is provided in the readme file.
    Language: English
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  • 183
    Publication Date: 2021-02-27
    Description: The software RST Evaluation is a series of scripts to semi-automatically evaluate shear experiments done at the Helmholtz Laboratory for Tectonic Modelling. In principle, it may be used for other measurements done in a similar setup, but it was build with our standardized workflow in mind. The shear experiments are done in a ring shear type shear cell rst.pc01 manufactured by D. Schulze (Details in ASTM standard D-6773). It uses an easy and reproducible workflow to determine yield properties, cohesion and dilational properties of a granular bulk material, such as sand or glass beads.
    Language: English
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  • 184
    Publication Date: 2021-02-28
    Description: This data is an high resolution Digital Elevation Model (DEM) generated for the Merapi summit by combining terrestrial laser scanning (TLS) and unmanned aerial vehicles (UAVs) photogrammetry data and TanDEM-X data acquired in the years between 2012 and 2017. The structures of the data are further analysed in Darmawan et al. 2017a (http://doi.org/10.1016/j.jvolgeores.2017.11.006), and a previous DEM was available in Darmawan et al. 2017b (https://doi.org/10.5880/GFZ.2.1.2017.003). The 3D point clouds of the different data were merged and interpolated to a raster format (Geotiff format).
    Language: English
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  • 185
    Publication Date: 2021-02-28
    Description: The Proterozoic Carpentaria province in northern Australia is host to several of the world’s largest clastic dominant (CD-type) massive sulphide deposits. These deposits are mostly hosted primarily in dolomitic silt- and mudstones. The hydrothermal alteration footprint of these CD-type systems is not well constrained, which poses challenges for the targeting of future discoveries. One important aspect to developing alteration models relates to defining the composition of the unaltered protolith to mineralization. In this dataset, we provide whole rock lithogeocheochemical data generated from samples obtained from drill-holes that intersected the mineralization in the Teena subbasin. A small number of samples are from 2 drill-holes from an adjoining subbasin (Myrtle) in the area. The samples were selected from stratigraphy of the Barney Creek Formation and are from the hangingwall to the mineralization in either subbasin. This data report includes bulk rock major, minor, and trace element composition. The data were generated using X-ray fluorescence, inductively coupled plasma mass spectrometry, and LECO analyses. Access to drill cores was granted by Teck Australia (Pty Ltd) and the drill core IDs and depths of individual samples are reported in the data table. For further details see: Magnall et al. (2021 - WHEN AVAILABLE)
    Language: English
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  • 186
    Publication Date: 2021-02-28
    Description: This dataset collects the results of a series of experiments carried out on air-filled cracks injected into pigskin gelatin blocks between September 2019 and May 2020 at GFZ German Research Centre for Geosciences in Potsdam (Germany). Such experiments were intended to simulate dike propagation in the upper crust, in settings where tectonic and surface unloading stress are dominant in determining the stress field within the medium. The gelatin blocks were laterally strained and rift-like excavations were moulded on their surfaces. These data include pictures of each experimental setup and video records of each injected crack, as well as tables collecting the measured arrival points of the cracks at the surface of the gelatin and relevant elastic and geometric parameters. The data publication is a Supplement to Mantiloni et al. (2020): "Stress inversion in a gelatin box: testing eruptive vent location forecasts with analog models" (Geophys. Res. Lett.), to which the reader is referred for further information.
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  • 187
    Publication Date: 2021-02-28
    Description: GFZ acts as a global analysis center of the International GNSS Service (IGS) and provides operationally ultra-rapid (last 24h), rapid (last day), and final (last week) solutions and contributes to the reprocessing activities of the IGS. The GFZ repro3 product solution series covers data from 1994 to 2020 and is published in daily and weekly files. The following satellite systems are contained: GPS (from 1994), GLONASS (from 2012), and Galileo (from 2014).
    Language: English
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  • 188
    Publication Date: 2021-03-17
    Description: The ability to constrain the petrogenesis of multiple serpentine generations recorded at the microscale is crucial for estimating the extent and conditions of modern versus fossil serpentinisation in ophiolites. To address matrix bias effects during oxygen isotope analysis by SIMS, we present the first investigation analysing antigorite in the compositional range Mg# = 77.5–99.5 mole %, using a CAMECA IMS‐1280 secondary ion mass spectrometer. Spot‐to‐spot homogeneity is ≤ 0.5‰ (2s) for the new antigorite reference materials. The relative bias between antigorite reference materials with different Mg/Fe ratios is described by a second‐order polynomial, and a maximum difference in bias of ~ 1.8‰ was measured for Mg# ~ 78 to 100. We observed a bias up to ~ 1.0‰ between lizardite and antigorite attributed to their different crystal structures. Orientation effects up to ~ 1‰ were observed in chrysotile. The new analytical protocol allowed the identification of oxygen isotope zoning up to ~ 7‰ in serpentine minerals from two serpentinites recovered from an area of active serpentinisation in the Samail ophiolite. Thus, in situ analysis is capable of resolving isotopic heterogeneity that may directly reflect changes in the physical and chemical conditions of multiple serpentinisation events in the Samail ophiolite.
    Language: English
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  • 189
    Publication Date: 2021-03-17
    Description: Quantifying surficial processes is of major importance to studies of continental evolution and landscape change. In this study we measure the concentration of the stable cosmogenic nuclide 21Ne and test whether it can be used to quantify erosion rates throughout the Phanerozoic (〉107 yr). This new tool will be of immense value in the research of tectonic and geodynamics of continental terrains. Cosmogenic 21Ne accumulates through multiple episodes of exposure. The passive margin of Gondwana offers a setting to test cosmogenic 21Ne as a tool for paleo-geomorphological research as well as determine the rates of surface processes since the establishment of the Pan African shield, ~540 Ma. Preliminary results are consistent with the hypothesis of increasing 21Ne concentrations with decreasing age and suggest that in the temporal scale of a sedimentary cycle, sediments spend most of their time buried and are in transport for only a very short time.
    Language: English
    Type: info:eu-repo/semantics/doctoralThesis
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  • 190
    Publication Date: 2021-03-16
    Description: Chlorophyll-a (Chl-a) and Total Suspended Solids (TSS) are both key indicators of the biophysical status of inland waters, and their continued monitoring is essential. Existing conventional methods (e.g., in situ monitoring) have shown that they are impractical due to their time and space limitations. The recently operated Sentinel-2A satellite offers the potential to have higher temporal, spatial, and spectral resolution images with no cost for monitoring water quality parameters of inland waters. The main aim of this study was to develop a semi-empirical model for predicting water quality parameters by combining Sentinel-2A data and machine learning methods using samples collected from several water reservoirs within the southern part of the Czech Republic, Central Europe. A combination of 10 spectral bands of the Sentinel-2A and 19 spectral indices, as independent variables, were used to train prediction models (i.e., Cubist) and then produce spatial distribution maps for both Chl-a and TSS. The results showed that the prediction accuracy based on Sentinel-2A was adequate for both Chl-a () and TSS (). The spatial distribution maps derived from Sentinel-2A performed well where Chl-a and TSS were relatively high. The temporal changes in both Chl-a and TSS could be seen in the distribution maps. The temporal changes are showing that The values of TSS dramatically changed in fishponds compared to sand lakes over time which might be due to indifferent management practices. Overall, it can be concluded that Sentinel-2A, when coupled with machine learning algorithms, could be employed as a reliable, inexpensive, and accurate instrument for monitoring the biophysical status of small inland waters like fishponds and sandpit lakes.
    Language: English
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  • 191
    Publication Date: 2021-03-25
    Description: In the EU-funded project Global Gravity-based Groundwater Product (G3P), we strive to combine data on terrestrial water storage from satellite gravimetry by the GRACE and GRACE-FO missions with existing products on water storage compartments from the Copernicus portfolio to establish a new cross-cutting product on groundwater storage variations with global coverage on a monthly basis. While the focus of G3P lies on incorporating observation-based Copernicus products, some model data has to be added to fill spatial and temporal gaps. This especially applies to water storage variations in surface water bodies, i.e., lakes and rivers, where little observation-based data is available. Altimetry-based data bases such as HYSOPE and the MGB model are available for large surface water bodies. However, to account for smaller water bodies and rivers, and to have a basis for assessing uncertainties of the entire approach, the integration of well-established models is desirable. A model we deem fit to these ends is Lisflood, which underpins the Global Flood Awareness System (GloFAS) of the Copernicus Emergency Management Service, and for which a recent global re-calibration is available. In this study, we evaluate Lisflood’s capability of modeling surface water storage variations in comparison to the above-mentioned observational data sources as well as the WaterGAP Global Hydrology Model (WGHM). As the target output of G3P is a 0.5° grid with monthly resolution,Lisflood’s output data will undergo an upscaling and temporal aggregation procedure which will also be subject of this study.
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  • 192
    Publication Date: 2021-03-25
    Description: In this study, the performance of ensemble precipitation forecasts of three numerical weather prediction (NWP) models within the TIGGE database as well as the integrated multi-satellite retrievals for global precipitation measurement (GPM), namely IMERG-RT V05B, for precipitation estimates were evaluated in recent severe floods in Iran over the March–April 2019 period. The evaluations were conducted in two modes: spatial distribution of precipitation and the dichotomous evaluation in four precipitation thresholds (25, 50, 75, and 100 mm per day). The results showed that the United Kingdom Met Office (UKMO) model, in terms of spatial coverage and satellite estimates as well as the precipitation amount, were closer to the observations. Although, generally, the models captured the spatial distribution of heavy precipitation events, the hot spots were not located in the correct area. The National Centers for Environmental Forecast (NCEP) model performed well at low precipitation thresholds, while at high thresholds, its performance decreased significantly. On the contrary, the accuracy of IMERG improved when the precipitation threshold increased. The UKMO had better forecasts than the other models at the 100 mm/day precipitation threshold, whereas the Medium-Range Weather Forecasts (ECMWF) had acceptable forecasts in all thresholds and was able to forecast precipitation events with a lower false alarm ratio and better detection when compared to other models. Although, the models and IMERG product underestimated or overestimated the amount of precipitation, but they were able to detect most extreme precipitation events. Overall, the results of this study show the IMERG precipitation estimates and NWP ensemble forecasts performed well in the three major flood events in spring 2019 in Iran. Given wide spread damages caused by the floods, the necessity of establishing an efficient flood warning system using the best precipitation products is advised.
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  • 193
    Publication Date: 2021-03-25
    Description: This study has been run in the context of the European Union research project G3P (Global Gravitybased Groundwater Product) on developing Groundwater storage (GW) as a new product for the EU Copernicus Services. GW variations can be derived on a global scale by subtracting from total water storage (TWS) variations based on the GRACE/GRACE-FO satellite missions variations in other water storage compartments such as soil moisture, snow, surface water bodies, and glaciers. Due to the nature of data acquisition by GRACE and GRACE-FO, the data need filtering in order to reduce North-South-oriented striping errors. However, this also leads to a spatially smoothed TWS signal. For a consistent subtraction of all individual storage compartments from GRACE-based TWS, the individual data sets for all other hydrological compartments need to be filtered in a similar way as GRACE-based TWS. In order to test different filter methods, we used compartmental water storage data of the global hydrological model WGHM. The decorrelation filter known as DDK filter that is routinely used for GRACE and GRACE-FO data introduced striping artifacts in the smoothed model data. Thus, we can conclude that the DDK filter is not suitable for filtering water storage data sets that do not exhibit GRACE-like correlated error patterns. Alternatively, an isotropic Gaussian filter might be used. The best filter width of the Gaussian filter is determined by minimizing the differences between the empirical spatial correlation functions of each water storage and the spatial correlation function of GRACE-based TWS. We also analyzed time variations of correlation lengths such as seasonal effects. Finally, the selected filter widths are applied to each compartmental storage data set to remove them from TWS and to obtain the GW variations.
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  • 194
    Publication Date: 2021-03-25
    Description: We estimate vertical rotation rates for 204 earthquakes that were induced by the 2018 stimulation of the Espoo/Helsinki geothermal reservoir from wavefield gradients across geophone arrays. The array-derived rotation rates from seismograms recorded at 6–9 km hypocentral distances vary between 10−9 and 10−7 rad s−1, indicating a comparable sensitivity to portable rotational instruments. Using co-located observations of translational and rotational motion, we estimate the local propagation direction and the apparent phase speed of SH waves, and compare these estimates with those obtained by S wave beamforming. Propagation directions generally align with the earthquake back azimuths, but both techniques show deviations indicative of heterogeneous seismic structure. The rotational method facilitates a station-by-station approach that resolves site specific variations that are controlled by the local geology. We measure apparent S wave speeds larger than 5 km s−1, consistent with steep incidence angles and high propagation velocities in the Fennoscandian Shield.
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  • 195
    Publication Date: 2021-03-25
    Description: Groundwater is one of the most important freshwater resources for mankind and for ecosystems. Assessing groundwater resources and developing sustainable water management plans based on this resource is a major field of activity for science, water authorities and consultancies worldwide. Due to its fundamental role in the Earth’s water and energy cycles, groundwater has been declared as an Essential Climate Variable (ECV) by GCOS, the Global Climate Observing System. However, within Copernicus - the European Earth Observation Programme – there is no service available yet to deliver data on this fundamental resource, nor is there any other data source worldwide that operationally provides information on changing groundwater resources in a consistent way, observation-based, and with global coverage. Filling this gap is the goal of the G3P (Global Gravity-based Groundwater Product) project, funded since the beginning of 2020 by the European Union. G3P aims at (1) capitalizing from the unique capability of GRACE and GRACE-FO satellite gravimetry as the only remote sensing technology to monitor subsurface mass variations and thus groundwater storage change for large areas with global coverage, and (2) incorporating and advancing a wealth of products on storage compartments of the water cycle that are already part of the Copernicus portfolio and will be used for separating out the groundwater storage variations from the gravity-based total terrestrial water storage, to finally (3) developing an operational global groundwater service prototype as a cross-cutting extension of the existing Copernicus portfolio. In this contribution, we present the concept of G3P and first results.
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  • 196
    Publication Date: 2021-03-27
    Description: This study reviews research data policies and author instructions of 31 journals from the Earth sciences and from biodiversity that are published by German learned societies or research institutions. The statements on data publishing of the journal´s data policies / author guidelines were matched to 14 pre-defined features of journal research data policies from Hrynaszkiewicz, I. et al. (2020) Developing a Research Data Policy Framework for All Journals and Publishers. Data Science Journal, 19: 5, pp. 1–15. https://doi.org/10.5334/dsj-2020-005.
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  • 197
    Publication Date: 2021-03-28
    Description: This data set was taken within the Perturbations of Earth Surface Processes by Large Earthquakes PRESSurE Project (https://www.gfz-potsdam.de/en/section/geomorphology/projects/pressure/) of the GFZ Potsdam. This project aims to better understand the role of earthquakes on earth surface processes. Strong earthquakes cause transient perturbations of the near Earth’s surface system. These include the widespread landsliding and subsequent mass movement and the loading of rivers with sediments. In addition, rock mass is shattered during the event, forming cracks that affect rock strength and hydrological conductivity. Often overlooked in the immediate aftermath of an earthquake, these perturbations can represent a major part of the overall disaster with an impact that can last for years before restoring to background conditions. Thus, the relaxation phase is part of the seismically induced change by an earthquake and needs to be monitored in order to understand the full impact of earthquakes on the Earth system. Early June 2015, shortly after the April 2015 Mw7.9 Gorkha earthquake, 6 automatic compact weather station were installed in the upper Bhotekoshi catchment covering an area ~50km2. The weather station network is centered around the Kahule Khola catchment, a small headwater catchment and is part of a wider data acquisition strategy including hydrological monitoring, seismometers, geophones and high resolution optical (RapidEye) as well as radar imagery (TanDEM TerraSAR-X). https://www.gfz-potsdam.de/sektion/geomorphologie/projekte/pressure/
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  • 198
    Publication Date: 2021-03-28
    Description: This data set was taken within the Perturbations of Earth Surface Processes by Large Earthquakes PRESSurE Project (https://www.gfz-potsdam.de/en/section/geomorphology/projects/pressure/) of the GFZ Potsdam. This project aims to better understand the role of earthquakes on earth surface processes. Strong earthquakes cause transient perturbations of the near Earth’s surface system. These include the widespread landsliding and subsequent mass movement and the loading of rivers with sediments. In addition, rock mass is shattered during the event, forming cracks that affect rock strength and hydrological conductivity. Often overlooked in the immediate aftermath of an earthquake, these perturbations can represent a major part of the overall disaster with an impact that can last for years before restoring to background conditions. Thus, the relaxation phase is part of the seismically induced change by an earthquake and needs to be monitored in order to understand the full impact of earthquakes on the Earth system. Early June 2015, shortly after the April 2015 Mw7.9 Gorkha earthquake, 6 automatic compact weather station were installed in the upper Bhotekoshi catchment covering an area ~50km2. The weather station network is centered around the Kahule Khola catchment, a small headwater catchment and is part of a wider data acquisition strategy including hydrological monitoring, seismometers, geophones and high resolution optical (RapidEye) as well as radar imagery (TanDEM TerraSAR-X). https://www.gfz-potsdam.de/sektion/geomorphologie/projekte/pressure/
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  • 199
    Publication Date: 2021-04-03
    Description: Minor release to include IGRF13 coefficients, expands the type of allowed inputs into the subsol routine, fixes several bugs in edge cases, expands testing support to include Python 3.6-3.9, updates the documentation, and updates the continuous integration testing environments.
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  • 200
    Publication Date: 2021-04-07
    Description: A common challenge for projects with multiple involved research institutes is a well-defined and productive collaboration. All parties measure and analyze different aspects, depend on each other, share common methods, and exchange the latest results, findings, and data. Today this exchange is often impeded by a lack of ready access to shared computing and storage resources. In our talk, we present a new and innovative remote procedure call (RPC) framework. We focus on a distributed setup, where project partners do not necessarily work at the same institute, and do not have access to each others resources. We present an application programming interface (API) developed in Python that enables scientists to collaboratively explore and analyze sets of distributed data. It offers the functionality to request remote data through a comfortable interface, and to share and invoke single computational methods or even entire analytical workflows and their results. The prototype enables researchers to make their methods accessible as a backend module running on their own infrastructure. Hence researchers from other institutes may apply the available methods through a lightweight python or Javascript API. In the end, the overhead for both, the backend developer and the remote user, is very low. The effort of implementing the necessary workflow and API usage equalizes the writing of code in a non-distributed setup. Besides that, data do not have to be downloaded locally, the analysis can be executed "close to the data" while using the institutional infrastructure where the eligible data set is stored. With our prototype, we demonstrate distributed data access and analysis workflows across institutional borders to enable effective scientific collaboration. This framework has been developed in a joint effort of the DataHub and Digitial Earth initiatives within the Research Centers of the Helmholtz Association of German Research Centres, HGF.
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