ALBERT

Description: Observations in polar regions show that sea ice deformations are often narrow linear features. These long bands of deformations are referred to as Linear Kinematic Features (LKFs). Viscous‐plastic sea ice models have the capability to simulate LKFs and more generally sea ice deformations. Moreover, viscous‐plastic models simulate a larger number and more refined LKFs as the spatial resolution is increased. Besides grid spacing, other aspects of a numerical implementation, such as the placement of velocities and the associated degrees of freedom, may impact the formation of simulated LKFs. To explore these effects this study compares numerical solutions of sea ice models with different velocity staggering in a benchmark problem. Discretizations based on A‐,B‐, and C‐grid systems on quadrilateral meshes have similar resolution properties as an approximation with an A‐grid staggering on triangular grids (with the same total number of vertices). CD‐grid approximations with a given grid spacing have properties, specifically the number and length of simulated LKFs, that are qualitatively similar to approximations on conventional Arakawa A‐grid, B‐grid, and C‐grid approaches with half the grid spacing or less, making the CD‐discretization more efficient with respect to grid resolution. One reason for this behavior is the fact that the CD‐grid approach has a higher number of degrees of freedom to discretize the velocity field. The higher effective resolution of the CD‐discretization makes it an attractive alternative to conventional discretizations.

Description: Plain Language Summary: Sea ice in the Arctic and Antarctic Oceans plays an important role in the exchange of heat and freshwater between the atmosphere and the ocean and hence in the climate in general. Satellite observations of polar regions show that the ice drift sometimes produces long features that are either cracks (leads) and zones of thicker sea ice (pressure ridges). This phenomenon is called deformation. It is mathematically described by the non‐uniform way in which the ice moves. For numerical models of sea ice motion it is difficult to represent this deformation accurately. Details of the numerics may affect the way these models simulate leads and ridges, their number and length. Specifically, we find by comparing different numerical models, that the way the model variables are ordered on a computational grid to solve the mathematical equations of sea ice motion has an effect of how many deformation features can be represented on a grid with a given spacing between grid points. A new discretization (ordering of model variables) turns out to resolve more details of the approximated field than traditional methods.

Description: Key Points: The placement of the sea ice velocity has a mayor influence on the number of simulated linear kinematic features (LKFs). The CD‐grid resolves twice as many LKFs compared to A, B, C‐grids. A, B, C‐grids on quadrilateral meshes resolve a similar number of LKFs as A‐grids on triangular meshes (with the same total number of nodes).

Description: Porosity is one of the key properties of fluvial sediments. It is defined as the ratio of pore volume to total volume. In river science, porosity is often assumed to be spatially constant, which might be a gross simplification of reality. Ignoring the spatial variations in porosity can cause errors in morphological, ecological, hydrological, hydrogeological and sedimentological applications. Although detailed information about spatial porosity variations can be obtained from porosity measurements at field sites, such information has never been collected where these variations might be important. In this study, field porosity measurements were carried out to quantify the magnitude of the spatial porosity variation for four different sedimentological environments of a braided river: a confluence, a tributary delta, a braid bar and a secondary channel. A nuclear density gauge was used for the measurement of porosity. The nuclear density gauge proved to be a time‐saving and labour‐saving technique that produces accurate porosity values with a root mean square error of 0.03. The four sedimentological environments showed significant differences in porosity, with mean porosity being lower for confluence and bar than for delta and secondary channel. Semi‐variogram analysis showed the absence of any spatial correlation in porosity for distances beyond 4 m. This shows that distance cannot be used as a parameter for porosity extrapolation in a fluvial system unless the extrapolation distance is less than 4 m. At least eight measurements of porosity are required to obtain a reliable estimate of mean porosity in a sedimentary environment, i.e. with uncertainty 〈0.03. Although grain size characteristics were found to have a significant impact on porosity, the relationships between these parameters and porosity were not very strong in this study. The unique porosity dataset, presented in this article, provides a valuable source of information for researchers and river managers.

Description: Deutsche Forschungsgemeinschaft

Description: Mixed sand‐ and gravel‐bed rivers record erosion, transport, and fining signals in their bedload size distributions. Thus, grain‐size data are imperative for studying these processes. However, collecting hundreds to thousands of pebble measurements in steep and dynamic high‐mountain river settings remains challenging. Using the recently published digital grain‐sizing algorithm PebbleCounts, we were able to survey seven large (≥ 1,000 m2) channel cross‐sections and measure thousands to tens‐of‐thousands of grains per survey along a 100‐km stretch of the trunk stream of the Toro Basin in Northwest Argentina. The study region traverses a steep topographic and environmental gradient on the eastern margin of the Central Andean Plateau. Careful counting and validation allows us to identify measurement errors and constrain percentile uncertainties using large sample sizes. In the coarse ≥2.5 cm fraction of bedload, only the uppermost size percentiles (≥95th) vary significantly downstream, whereas the 50th and 84th percentiles show less variability. We note a relation between increases in these upper percentiles and along‐channel junctions with large, steep tributaries. This signal is strongly influenced by lithology and geologic structures, and mixed with local hillslope input. In steep catchments like the Toro Basin, we suggest nonlinear relationships between geomorphic metrics and grain size, whereby the steepest parts of the landscape exert primary control on the upper grain‐size percentiles. Thus, average or median metrics that do not apply weights or thresholds to steeper topography may be less predictive of grain‐size distributions in such settings.

Description: Plain Language Summary: Rock fragments on hillsides are transported to rivers, eventually becoming pebbles, sand, and mud as they are carried downstream by flowing water. The initial size of the pebbles, the way the size changes downstream, and the overprinting of the sizes with new pebbles from other hills and tributaries all form a complex process that can be difficult to disentangle. Yet studying the size of the pebbles at a given stream location or in a sedimentary deposit can provide insights into the conditions of their transport in terms of local upstream patterns of erosion, tectonics, and climate. We show that just looking at the size of the large pebbles on a riverbed can be used to infer the sources of material, but, since there are fewer large pebbles, they require more measurements to quantify. This necessitates new methods for pebble measurement using modern image‐processing tools.

Description: Key Points: Complex grain‐size distributions in dynamic mountain rivers can be computed via thousands of measurements from PebbleCounts. Many measurements allow robust estimation of higher percentiles and we observe the most significant changes in the ≥95th percentile. Downstream grain‐size variation is nonlinearly related to variations in topographic steepness and lithology.

Description: Deutsches Zentrum für Luft‐ und Raumfahrt (DLR) http://dx.doi.org/10.13039/501100002946

Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347

Description: Brandenburger Staatsministerium für Wissenschaft, Forschung und Kultur (MWFK) http://dx.doi.org/10.13039/501100004581

Description: https://zenodo.org/record/5089789

Description: A reanalysis is a physically consistent set of optimally merged simulated model states and historical observational data, using data assimilation. High computational costs for modeled processes and assimilation algorithms has led to Earth system specific reanalysis products for the atmosphere, the ocean and the land separately. Recent developments include the advanced uncertainty quantification and the generation of biogeochemical reanalysis for land and ocean. Here, we review atmospheric and oceanic reanalyzes, and more in detail biogeochemical ocean and terrestrial reanalyzes. In particular, we identify land surface, hydrologic and carbon cycle reanalyzes which are nowadays produced in targeted projects for very specific purposes. Although a future joint reanalysis of land surface, hydrologic, and carbon processes represents an analysis of important ecosystem variables, biotic ecosystem variables are assimilated only to a very limited extent. Continuous data sets of ecosystem variables are needed to explore biotic‐abiotic interactions and the response of ecosystems to global change. Based on the review of existing achievements, we identify five major steps required to develop terrestrial ecosystem reanalysis to deliver continuous data streams on ecosystem dynamics.

Description: Plain Language Summary: A reanalysis is a unique set of continuous variables produced by optimally merging a numerical model and observed data. The data are merged with the model using available uncertainty estimates to generate the best possible estimate of the target variables. The framework for generating a reanalysis consists of the model, the data, and the model‐data‐fusion algorithm. The very specific requirements of reanalysis frameworks have led to the development of Earth‐compartment specific reanalysis for the atmosphere, the ocean and land. Here, we review atmospheric and oceanic reanalyzes, and in more detail biogeochemical ocean and terrestrial reanalyzes. In particular, we identify land surface, hydrologic, and carbon cycle reanalyzes which are nowadays produced in targeted projects for very specific purposes. Based on a review of existing achievements, we identify five major steps required to develop reanalysis for terrestrial ecosystem to shed more light on biotic and abiotic interactions. In the future, terrestrial ecosystem reanalysis will deliver continuous data streams on the state and the development of terrestrial ecosystems.

Description: Key Points: Reanalyzes provide decades‐long model‐data‐driven harmonized and continuous data sets for new scientific discoveries. Novel global scale reanalyzes quantify the biogeochemical ocean cycle, terrestrial carbon cycle, land surface, and hydrologic processes. New observation technology and modeling capabilities allow in the near future production of advanced terrestrial ecosystem reanalysis.

Description: European Union's Horizon 2020 research and innovation programme

Description: Deutsche Forschungsgemeinschaft

Description: U.S. Department of Energy

Description: Emory University's Halle Institute for Global Research and the Halle Foundation Collaborative Research

Description: NSF

Description: NASA

Description: Natural Environment Research Council

Description: European Union'’s Horizon 2020 research and innovation programme

Description: NSERC Discovery program, the Ocean Frontier Institute, and MEOPAR

Description: Research Foundation Flanders (FWO)

Description: Helmholtz Association

Description: NASA Terrestrial Ecosystems

Description: Efficient compositional models are required to simulate underground gas storage in porous formations where, for example, gas quality (such as purity) and loss of gas due to dissolution are of interest. We first extend the concept of vertical equilibrium (VE) to compositional flow, and derive a compositional VE model by vertical integration. Second, we present a hybrid model that couples the efficient compositional VE model to a compositional full‐dimensional model. Subdomains, where the compositional VE model is valid, are identified during simulation based on a VE criterion that compares the vertical profiles of relative permeability at equilibrium to the ones simulated by the full‐dimensional model. We demonstrate the applicability of the hybrid model by simulating hydrogen storage in a radially symmetric, heterogeneous porous aquifer. The hybrid model shows excellent adaptivity over space and time for different permeability values in the heterogeneous region, and compares well to the full‐dimensional model while being computationally efficient, resulting in a runtime of roughly one‐third of the full‐dimensional model. Based on the results, we assume that for larger simulation scales, the efficiency of this new model will increase even more.

Description: Key Points: A compositional vertical equilibrium model is coupled to its full‐dimensional counterpart. A criterion is developed to adaptively identify and assign regions where the vertical equilibrium model is applicable during simulation. A test case of hydrogen storage in a heterogeneous porous aquifer demonstrates efficiency and accuracy of the hybrid model.

Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Description: https://git.iws.uni-stuttgart.de/dumux-pub/Becker2021b.git

Description: Basal melting of marine‐terminating glaciers, through its impact on the forces that control the flow of the glaciers, is one of the major factors determining sea level rise in a world of global warming. Detailed quantitative understanding of dynamic and thermodynamic processes in melt‐water plumes underneath the ice‐ocean interface is essential for calculating the subglacial melt rate. The aim of this study is therefore to develop a numerical model of high spatial and process resolution to consistently reproduce the transports of heat and salt from the ambient water across the plume into the glacial ice. Based on boundary layer relations for momentum and tracers, stationary analytical solutions for the vertical structure of subglacial non‐rotational plumes are derived, including entrainment at the plume base. These solutions are used to develop and test convergent numerical formulations for the momentum and tracer fluxes across the ice‐ocean interface. After implementation of these formulations into a water‐column model coupled to a second‐moment turbulence closure model, simulations of a transient rotational subglacial plume are performed. The simulated entrainment rate of ambient water entering the plume at its base is compared to existing entrainment parameterizations based on bulk properties of the plume. A sensitivity study with variations of interfacial slope, interfacial roughness and ambient water temperature reveals substantial performance differences between these bulk formulations. An existing entrainment parameterization based on the Froude number and the Ekman number proves to have the highest predictive skill. Recalibration to subglacial plumes using a variable drag coefficient further improves its performance.

Description: Plain Language Summary: In a world of global warming, the melting of glaciers terminating as floating ice tongues into the oceans of Arctic and Antarctic regions allows those glaciers to flow faster and hence to make a considerable contribution to global mean sea‐level rise. Underneath the ice‐ocean interface, turbulent currents of the order of 10 m thickness (so‐called plumes) develop that transport the melt water from the grounding line where the glacier enters the ocean toward the calving front that marks the seaward end of the glacier. At its base, ambient relatively warm and salty ocean water is mixed into the plumes and is vertically transported toward the ice‐ocean interface, where the melting is increased due to the additional heat supply. Understanding these processes is essential for their incorporation into computer models for the prediction of such melt processes. In this study, an accurate simulation model for the water column is constructed that is able to consistently reproduce these processes. The algorithms developed here are proven to provide reliable results also for models with only a few grid points across the plume and can therefore be implemented into climate models with surface‐following coordinates to more accurately simulate future scenarios of sea level rise.

Description: Key Points: A vertically resolving model with second‐moment turbulence closure has been constructed for subglacial plumes. Convergent numerical formulations for the ocean‐to‐ice fluxes of momentum, freshwater and heat have been derived from an analytical model. Model results are consistent with bulk parameterizations for the entrainment of ambient water.

Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347

Description: https://doi.org/10.5281/zenodo.6203838

Description: Hydrogen is a promising alternative to carbon based energy carriers and may be stored in large quantities in subsurface storage deposits. This work assesses the impact of static (density and phase equilibria) and dynamic (viscosity and diffusion coefficients) properties on the pressure field during the injection and extraction of hydrogen in the porous subsurface. In a first step, we derive transport properties for water, hydrogen and their mixture using the Perturbed‐Chain Statistical Associating Fluid Theory equation of state in combination with an entropy scaling approach and compare model predictions to alternative models from the literature. Our model compares excellently to experimental transport coefficients and models from literature with a higher number of adjustable parameters, such as GERG2008, and shows a clear improvement over empirical correlations for transport coefficients of hydrogen. In a second step, we determine the effect of further model reduction by comparing our against a much simpler model applying empirical transport coefficients from the literature. For this purpose, hydrogen is periodically injected into and extracted out of a dome‐shaped porous aquifer under a caprock. Our results show that density and viscosity of hydrogen have the highest impact on the pressure field, and that a thermodynamic model like the new model presented here is essential for modeling the storage aquifer, while keeping the number of coefficients at a minimum. In diffusion‐dominated settings such as the diffusion of hydrogen through the caprock, our developed diffusion coefficients show a much improved dependence on temperature and pressure, leading to a more accurate approximation of the diffusive fluxes.

Description: Key Points: We model the phase behavior of pure hydrogen and the binary hydrogen‐water mixture using the Perturbed‐Chain Statistical Associating Fluid Theory equation of state. New entropy scaling relations for the transport properties of hydrogen and water and diffusion coefficients of their mixture are derived. The impact of the newly derived fluid properties is analyzed for a scenario of hydrogen storage in a porous aquifer.

Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Description: https://git.iws.uni-stuttgart.de/dumux-pub/sauerborn2020a

Description: Vlasov solvers that operate on a phase‐space grid are highly accurate but also numerically demanding. Coarse velocity space resolutions, which are largely unproblematic in particle‐in‐cell (PIC) simulations, can lead to numerical heating or oscillations in continuum Vlasov methods. To address this issue, we present a new dual Vlasov solver which is based on an established positivity preserving advection scheme for the update of the distribution function and an energy conserving partial differential equation solver for the kinetic update of mean velocity and temperature. The solvers work together via moment fitting during which the maximum entropy part of the distribution function is replaced by the solution from the partial differential equation solver. This numerical scheme makes continuum Vlasov methods competitive with PIC methods concerning computational cost and enables us to model large scale reconnection in Earth's magnetosphere with a fully kinetic continuum method. The simulation results agree well with measurements by the MMS spacecraft.

Description: Key Points: A moment fitting continuum Vlasov solver is presented that preserves positivity of the distribution function and conserves total energy. The method behaves well at low velocity space resolutions, making it competitive with PIC methods concerning computational cost. There is good agreement of the simulations with measurements of magnetic reconnection by the MMS spacecraft.

Description: Helmholtz Association (亥姆霍兹联合会致力) http://dx.doi.org/10.13039/501100009318

Description: https://vlasov.tp1.ruhr-uni-bochum.de/data/paper-JGR-2021

Description: In recent years, Spatial Markov Models have gained popularity in simulating solute transport in heterogeneous formations. They describe the transition times of particles between equidistant observation planes by statistical distributions, assuming correlation of the transit times of individual particles between subsequent steps. By this, the approach naturally captures preasymptotic solute dispersion. In this study, we analyze Spatial Markov Models assuming bivariate log‐normal distributions of the particle slowness (i.e., the inverse velocity) in subsequent transitions. The model is fully parameterized by the mean Eulerian velocity, the variance of the log‐slowness, and the correlation coefficient of log‐slowness in subsequent steps. We derive closed‐form expressions for distance‐dependent ensemble dispersion, which is defined in terms of the second‐central moments of the solute breakthrough curves. We relate the coefficients to the properties of the underlying log‐hydraulic conductivity field assuming second‐order stationarity. The results are consistent with linear stochastic theory in the limit of small log‐conductivity variances, while the approach naturally extends to high‐variance cases. We demonstrate the validity of the approach by comparison to three‐dimensional particle‐tracking simulations of advective transport in heterogeneous media with isotropic, exponential correlation structure for log‐conductivity variances up to five. This study contributes to relating solute dispersion to metrics of the porous‐medium structure in cases of strong heterogeneity.

Description: Key Points: We derive closed‐form expressions of ensemble dispersion in the spatial‐Markov framework of solute transport. The expressions are consistent with linear theory in the limit of small log‐conductivity variances, but extend to high‐variance cases. Comparison to particle‐tracking simulations of advective transport in 3‐D heterogeneous domains show excellent agreement.

Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Description: https://doi.org/10.5281/zenodo.6554308

Description: https://www.hsl.rl.ac.uk/catalogue/hsl_mi20.html

Description: This publication developed from the 5th International Colloquium on “Historical Earthquakes, Paleoseismology, Neotectonics and Seismic Hazard” which was held from 11 to 13 October 2017 at the Federal Institute for Geosciences and Natural Resources (BGR) in Hannover, Germany. In this colloquium, 75 experts from 17 countries presented and discussed recent results, ongoing studies and planned projects on the topics historical earthquakes, macroseismology, archeoseismology, paleoseismology, earthquake catalogues and databases, active faults, seismotectonics, neotectonics, and seismic hazard assessment.

Description: Deutsche Gesellschaft für Erdbebeningenieurwesen und Baudynamik

Description: 〈b〉Introduction: Historical Earthquakes, Paleoseismology, Neotectonics and Seismic Hazard: New Insights and Suggested Procedures〈/b〉 〈br〉 〈i〉Diethelm Kaiser〈/i〉 〈br〉 〈a href="https://doi.org/10.23689/fidgeo-3868"〉 DOI: https://doi.org/10.23689/fidgeo-3868〈/a〉〈br〉 〈br〉〈/br〉 〈b〉Best practice of macroseismic intensity assessment applied to the earthquake catalogue of southwestern Germany〈/b〉 〈br〉 〈i〉 Wolfgang Brüstle, Uwe Braumann, Silke Hock and Fee-Alexandra Rodler 〈/i〉〈br〉 〈a href="https://doi.org/10.23689/fidgeo-3864"〉 DOI:https://doi.org/10.23689/fidgeo-3864〈/a〉〈br〉 〈br〉〈/br〉 〈b〉The earthquake of September 3, 1770 near Alfhausen (Lower Saxony, Germany): a real, doubtful, or a fake event? 〈/b〉 〈br〉 〈i〉Günter Leydecker and Klaus Lehmann 〈/i〉 〈br〉〈a href="https://doi.org/10.23689/fidgeo-3865"〉 DOI: https://doi.org/10.23689/fidgeo-3865〈/a〉〈br〉 〈br〉〈/br〉 〈b〉How well does known seismicity between the Lower Rhine Graben and southern North Sea reflect future earthquake activity? 〈/b〉 〈br〉 〈i〉Thierry Camelbeeck, Kris Vanneste, Koen Verbeeck, David Garcia-Moreno, Koen Van Noten and Thomas Lecocq 〈/i〉 〈br〉〈a href="https://doi.org/10.23689/fidgeo-3866"〉 DOI: https://doi.org/10.23689/fidgeo-3866〈/a〉〈br〉 〈br〉〈/br〉 〈b〉The Paleoseismic Database of Germany and Adjacent Regions PalSeisDB v1.0〈/b〉〈br〉 〈i〉Jochen Hürtgen, Klaus Reicherter, Thomas Spies, Claudia Geisler and Jörg Schlittenhardt 〈/i〉 〈br〉〈a href="https://doi.org/10.23689/fidgeo-3867"〉 DOI: https://doi.org/10.23689/fidgeo-3867〈/a〉〈br〉

Description: research

Description: Atmospheric delay corrections for satellite altimetry measurements are essential for deriving highly accurate sea surface heights and reliable global mean sea level (GMSL) trend estimates. A commonly used method to correct for ionospheric path delays are the usage of GNSS‐based Global Ionospheric Maps (GIM). The different orbit heights of GNSS and altimeter satellites require an adaption of GIM corrections to account for free electrons in the Earth plasmasphere. This study shows that the widely used scaling approach based on the International Reference Ionosphere (IRI) is not able to accurately scale the GIM models. The impact of neglecting the plasmaspheric part of the atmosphere strongly correlates with the solar activity of about 11 years. This manifests itself as trend errors in global GMSL. For the Jason period (2002–2021) a trend error of 0.17 mm/year can be shown, which is even larger for smaller periods (e.g., 1.0 mm/year for Jason‐1 lifetime). The application of an additional constant scaling factor of 0.886 can reduce the trend differences to below 0.05 mm/year.

Description: Plain Language Summary: Global mean sea level (GMSL) rise is an important indicator for climate change. To precisely measure this quantity that is only in the order of about 3 mm/year, satellite altimeters are used. Their observations have to be corrected for influences in the Earth atmosphere. This study shows deficiencies in one commonly used correction data set. These corrections, based on observations from the Global Navigation Satellite Systems (GNSS) are not accounting for the higher part of the atmosphere, the plasmasphere. Neglecting this influence derives systematic errors with a 11 years cycle that impacts the estimation of GMSL by up to 1 mm/year, depending on the period under investigation. It is recommended to apply an additional scaling of the available corrections in order to reduce the trend error to below 0.05 mm/year.

Description: Key Points: Global Ionospheric Map corrections in altimetry Sensor Geophysical Data Records are not fully scaled to account for plasmaspheric electron content. Neglecting the plasmaspheric effect leads to trends of up to 1 mm/year in Global mean sea level estimates. The additional application of a scale factor improves the consistency in trend with respect to dual‐frequency satellite altimetry data.

Description: https://podaac.jpl.nasa.gov/

Description: https://www.aviso.altimetry.fr/

Description: https://openadb.dgfi.tum.de/en/products/vertical-total-electron-content/

Description: The subduction of serpentinized slabs is the dominant process to transport “water” into Earth's mantle, and plays a pivotal role for subduction dynamics. Antigorite, the most abundant serpentine mineral in subduction settings, may imprint a seismic signature on serpentinized slabs, making them seismically distinguishable from the dry, non‐serpentinized ones. However, the complete single‐crystal elasticity of antigorite has not been experimentally constrained at high pressures, hindering the use of seismological approaches to detect serpentinization in subducting slabs. Here, we report the full elastic stiffness tensor of antigorite by single‐crystal Brillouin spectroscopy and X‐ray diffraction up to 7.71(5) GPa. We use our results to model seismic properties of antigorite‐bearing rocks and show that their seismological detectability depends on the geometrical relation between seismic wave paths and foliation of serpentinized rocks. In particular, we demonstrate that seismic shear anisotropy shows low sensitivity to serpentinization for a range of relevant geometries.

Description: Plain Language Summary: The subduction of serpentinized slabs plays a key role in the deep recycling of water into the Earth's interior. Antigorite is the main serpentine mineral in subducting slabs, and the most important carrier of water. Antigorite‐bearing rocks are predicted to have a distinct seismic signature, potentially allowing them to be detected with seismological approaches. However, our current knowledge on seismic properties of antigorite‐bearing rocks is limited, mostly hampered by a lack of experimental constraints on single‐crystal elasticity of antigorite at relevant pressures. In this study, state‐of‐the‐art techniques were employed to produce the first experimental description of the complete high‐pressure elasticity of antigorite single crystals. Our experimental data set was implemented in the modeling of seismic properties of antigorite‐bearing rocks at pressures relevant for subduction. Our results were used to discuss the relation between seismic wave path and shear wave anisotropy in serpentinized slabs, and challenge the use of shear wave splitting as a proxy for serpentinization in slabs.

Description: Key Points: Single‐crystal elasticity of antigorite at high pressures is determined by Brillouin spectroscopy and X‐ray diffraction experiments. Seismic signature of serpentinized slabs is constrained in a relevant composition‐pressure space. Serpentinization in slabs may be undetectable through shear wave anisotropy.

Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Description: EC Horizon 2020 Framework Programme http://dx.doi.org/10.13039/100010661

Description: https://doi.org/10.6084/m9.figshare.20348748

Description: https://doi.org/10.6084/m9.figshare.20348781

Description: Over the last years, installations of wind turbines (WTs) increased worldwide. Owing to negative effects on humans, WTs are often installed in areas with low population density. Because of low anthropogenic noise, these areas are also well suited for sites of seismological stations. As a consequence, WTs are often installed in the same areas as seismological stations. By comparing the noise in recorded data before and after installation of WTs, seismologists noticed a substantial worsening of station quality leading to conflicts between the operators of WTs and earthquake services. In this study, we compare different techniques to reduce or eliminate the disturbing signal from WTs at seismological stations. For this purpose, we selected a seismological station that shows a significant correlation between the power spectral density and the hourly windspeed measurements. Usually, spectral filtering is used to suppress noise in seismic data processing. However, this approach is not effective when noise and signal have overlapping frequency bands which is the case for WT noise. As a first method, we applied the continuous wavelet transform (CWT) on our data to obtain a time-scale representation. From this representation, we estimated a noise threshold function (Langston & Mousavi, 2019) either from noise before the theoretical P-arrival (pre-noise) or using a noise signal from the past with similar ground velocity conditions at the surrounding WTs. Therefore, we installed low cost seismometers at the surrounding WTs to find similar signals at each WT. From these similar signals, we obtain a noise model at the seismological station, which is used to estimate the threshold function. As a second method, we used a denoising autoencoder (DAE) that learns mapping functions to distinguish between noise and signal (Zhu et al., 2019). In our tests, the threshold function performs well when the event is visible in the raw or spectral filtered data, but it fails when WT noise dominates and the event is hidden. In these cases, the DAE removes the WT noise from the data. However, the DAE must be trained with typical noise samples and high signal-to-noise ratio events to distinguish between signal and interfering noise. Using the threshold function and pre-noise can be applied immediately on real-time data and has a low computational cost. Using a noise model from our prerecorded database at the seismological station does not improve the result and it is more time consuming to find similar ground velocity conditions at the surrounding WTs.

Description: poster

Description: As part of the German continental seismic reflection program (Deutsches Kontinentales Reflexionsseismisches Programm, DEKORP), three large seismic traverses (with the sub-profiles: DEKORP'84-2S and '86-2N; DEKORP'88-9N; DEKORP'90-3A and '90-3B) were measured in the state of Hesse in Germany. The main research topic of DEKORP were deep seismic studies to investigate the lithospheric structure beneath Germany. Thus, for acquisition, strong sources were used to image in these depths, resulting in an excellent S/N ratio, but the main focus was not on the uppermost kilometres. From today's perspective, however, this depth range is of great interest for a wide range of possible technical applications (including medium-deep and deep geothermal projects). The DEKORP profiles cover approx. 450 km in the state of Hesse and mostly cross areas where only insufficient geological data exist (i.e. only few deep boreholes). In order to close or reduce these knowledge gaps, these DEKORP lines were reprocessed in 2019/20. The focus of the reprocessing was on improving the resolution / mapping of geological structures down to a depth of 6 km (approx. 3 s TWT) to describe the prolongation of faults and geological structures in more detail than in previous studies. Nevertheless, deeper structures were also reinterpreted and compared to previous interpretations. The results were directly incorporated into the new geological 3D model of the state of Hesse, developed by the Technical University of Darmstadt (Hessen3D 2.0, BMWi-FKZ: 0325944). In order to achieve these goals and in view of the fact that today's processing methods have improved considerably compared to the 1990‘s, a state-of-the-art reprocessing was applied for all DEKORP profiles traversing the state of Hesse. In comparison to the original processing, additional processing steps like CRS instead of CDP stacking, turning-ray tomography and prestack depth migration were carried out. We present exemplary results of the reprocessing as well as initial geological reinterpretations for the profile DEKORP'88-9N.

Description: poster

Description: The work presented here is part of ongoing studies in the AlpArray initiative and the priority program "MB-4D" regarding the modelling of the lithosphere in the Ligurian Sea (northwestern Mediterranean Sea). It will be based on constraining data from LOBSTER and LISA campaigns of past GEOMAR projects and a study in our research group at CAU Kiel. Our motivation is the combination and interdisciplinary interpretation of independent information from geology, tectonics, geophysics, and petrology. The existing gravity fields, especially the new compilation of the AlpArray Gravity Research Group (AAGRG) is considered as database (high resolution Free Air- and Bouguer anomalies) and the isostatic residual field, besides data of the ICGEM Potsdam (disturbance) and the ESA GOCE gradients for gravity and data for the magnetic field anomaly. The gravity and magnetic fields are analyzed using Euler deconvolution with regularization (R. Pašteka, Comenius University Bratislava) and application of curvature analysis we use both, the fields themselves and their gradients. Besides the calculation of the so-called "3rd derivative" of the gravity potential, we also investigate a possible use of the invariants of the gravity field based on gradient data and compare and correlate the results with structural and tectonic maps in the area of the Ligurian Sea and the adjacent French and Italian mainland. The findings from these comparisons will later be used to initiate the compilation of 3D density and susceptibility models for the studied region.

Description: poster

Description: FloodRisk is an interdisciplinary project focusing on the effects of mine water level rise in bandoned coal mine regions in Germany. Such effects are heterogeneous ground uplift, stress changes due to the change in pore pressure and the reactivation of potential faults. One of the most directly measurable effects is certainly the induced micro seismicity. It is known from previous studies that the flooding of old mines can lead to a renewed increase level in induced micro seismicity in these regions. In this study the relationship between mine water rise, fluid-induced stress changes and induced seismicity in the Haus Aden dewatering area in the eastern Ruhr area (Germany) will be investigated in more detail. For this purpose, we operate a network of currently 21 short period seismic stations in the region of the former "Bergwerk Ost" colliery, which had the highest seismicity rate in the Ruhr area during active underground coal mining. This network is still to be expanded to cover the entire water drainage area, about 30 Raspberry Shake sensors are waiting for the possibility of installation. Nevertheless, the existing network registered almost 1000 induced micro seismic events in a magnitude range from -0.7 up to 2.6 MLv. Many of these events are spatially clustered and some show quite high waveform similarity. This allows relative localisation and can increase the accuracy of the location. The depth location of the earthquakes, within the limits of localisation accuracy, agrees very well with the distribution of seismicity at the time of active mining. The spatial distribution so far seems to be limited by a large inactive transverse fault in the west. It needs to be clarified what influence this fault has on the propagation of mine water in the underground. The measured temporal trend of the mine water level, after pumps were shut down in mid-2019, shows a strong correlation with the temporal evolution of the observed micro seismicity. In the first months after the pumps are switched off, the water levels at the observation points rise only slowly and isolated microseismic events occur again. In November 2019, the rise in water levels doubled and at the same time, the strongest induced event in the measurement period was recorded with a magnitude of 2.6 MLv . In the following months, the seismicity rate ranged from 8 to 34 events above 0.5 MLv per month, some of which were felt.

Description: Bundesministerium für Bildung und Forschung

Description: poster

Description: We introduce an approach for 3D joint interpretation of potential fields and its derivatives under the condition of constraining data and information. The interactive 3D gravity and magnetic application IGMAS (Interactive Gravity and Magnetic Application System) has been around for more than 30 years, initially developed on a mainframe and then transferred to the first DOS PCs, before it was adapted to Linux in the ’90s and finally implemented as a cross-platform Java application with GUI. Since 2019 IGMAS+ is maintained and developed in the Helmholtz Centre Potsdam – GFZ German Research Centre by the staff of Section 4.5 – Basin Modelling and ID2 – eScience Centre. The core of IGMAS+ applies an analytical solution of the volume integral for the gravity and magnetic effect of a homogeneous body. It is based on the reduction of the three-folded integral to an integral over the bounding polyhedrons that are formed by triangles. Later the algorithm has been extended to cover all elements of the gravity tensor as well and the optimized storage enables fast leastsquares inversion of densities and changes to the model geometry and this flexibility makes geometry changes easy. Because of the triangular model structure of model interfaces, IGMAS can handle complex structures (multi- Z surfaces) like the overhangs of salt domes and variable densities due to voxelization. To account for the curvature of the Earth, we use spherical geometries. Therefore IGMAS+ is capable to handle models from big-scale to regional and small-scale models (meters) used in Applied Geophysics.

Description: poster

Description: A new crustal model of the Volga-Uralian subcraton was built. The compilation of the model was subdivided in two steps: (1) inverse gravity modeling followed by (2) thorough forward gravity modeling. For inverse gravity modeling GOCE gravity gradients were used. The effect of the Earth sphericity was taken into account by using tesseroids. Density contrasts between crust and mantle were varied laterally according to the tectonic units present in the region. The model is constrained by the available seismic data including receiver function studies, and deep reflection and refraction profiles. The Moho discontinuity obtained during the gravity inversion was consequently modified, and complemented by the sedimentary cover, upper crust, lower crust, and lithospheric mantle layers in the process of forward gravity modeling. Obtained model showed crustal thickness variation from 34 to more than 55 km in some areas. The thinnest crust with the thickness below 40 km appeared on the Pericaspian basin with the thickest sedimentary column. A relatively thin crust was found along the central Russia rift system, while the thickest crust is located underneath Ural Mountains as well as in the center of the Volga-Uralian subcraton. In both areas the crustal thickness exceeds 50 km. At the same time, the gravity misfit of ca. 95 mGal between the measured Bouguer gravity anomaly and forward calculated gravity field was revealed in the central area of the Volga-Uralian subcraton. This misfit was interpreted and modeled as high-density lower crust which can possibly represent an underplated material. In the end, the new crustal model of Volga-Uralian subcraton respects the gravity and seismic constraints, and reflects the main geological features of the region. This model will be used for further geothermal analysis of the area.

Description: poster

Description: poster

Description: This presentation summarizes input data, procedures and results of probabilistic seismic hazard assessment (PSHA) in Bangladesh in the framework of the project ‘Geo information for Urban Planning and Adaptation to Climate Change’. It is a cooperation of the Geological Survey of Bangladesh (GSB) and the Federal Institute for Geosciences and Natural Resources (BGR) of Germany. The main aim of the project is to provide city planners with “Ground Suitability Maps”, which display different geo-factors. Seismic hazard is one of the geo-factors that contributes to these maps. For the derivation of “Ground Suitability Maps”, the influence of the local underground conditions will be taken into account additionally. A major part of Bangladesh is located in earthquake prone regions due to active tectonics. The Indian plate moves north-eastward towards the Eurasian plate at a velocity of about 6 cm/year. This motion leads to thrusting to the north (Himalaya) and to subduction to the east together with strike-slip mechanism. The thrusting and subduction processes have caused large historical earthquakes even inside Bangladesh (e.g. 1885 Bengal Earthquake M7 and 1918 Srimangal Earthquake M7.6). Therefore, it is crucial to assess seismic hazard in urban planning in Bangladesh. The input databases were compiled from the literature, reviewed and evaluated in this study. These are earthquake catalogs, the distribution of active faults and ground motion prediction equations. The most consistent and reliable databases were selected to be used in PSHA. The data of the earthquake catalog were declustered to eliminate the duplicated events, aftershocks and foreshocks. The spatial distribution of areal seismic sources was characterized using the distributions of earthquakes in the catalog and active faults. The completeness analysis of the earthquake catalog was performed and the Gutenberg-Richter magnitude recurrence distribution was derived for each seismic source. The results of PSHA are presented in the form of peak ground acceleration (PGA) maps with 10% exceedance probability in 50 years. As usual in regional PSHA, the results were compiled assuming bedrock as underground condition (so-called engineering bedrock with shear velocity of Vs30≥760 m/s). The northern and eastern parts of Bangladesh show the highest seismic hazard with PGA around 0.4 g with 10% exceedance probability in 50 years. This observation was expected because of the active tectonics in these parts.

Description: poster

Description: As part of the EPOS-Norway infrastructure project, NORSAR received funding from the Research Council of Norway for a new regional seismic array on Bjørnøya (Bear Island) in the European Arctic. After along planning phase, a six-element broadband array was installed by NORSAR staff in August 2019 and has been providing data to NORSAR in near real-time since then. Due to several logistical and administrative constraints the 6-element array has an aperture of only 300 m. All sites are equipped with Kinemetrics MBB-2 sensors and Earth Data EDR-209 digitizers that are installed in near-surface vaults. Data are automatically copied to the Norwegian node of the European Integrated Data Archive (EIDA) and are openly available. Due to environmental restrictions less than the planned 9 array sites could be installed on Bjørnøya and the non-used instruments are now available to extend the broadband station Hornsund (HSPB), Southern Spitsbergen, to another small aperture broadband array, also with 6 sites. The array installation had to be postponed because of the ongoing pandemic and is now planned for the Arctic summer 2021.

Description: poster

Description: Seismotectonic regions are a basic input in seismic hazard assessment. Several seismotectonic zonations for Germany have been proposed in the past. We have developed a new regionalization based on the definition in the German Nuclear Safety Standard: “A seismotectonic unit is a region for which uniformity is assumed regarding seismic activity, geological structure and development and, in particular, regarding neotectonic conditions”. Our new concept aims for transparent implementation of geological criteria, which we initially analyze separately from seismicity. We strive for a better documentation and justification of the geological elements used to delimit seismotectonic regions, based on an analysis of the geological evolution in six time slices from the Permian (300 Ma) to the Present. The time slices are separated by marked changes in the tectonic regime and associated with the development of new fault systems or reactivation of existing ones. The present-day fault network comprises faults from all time slices. For each time slice, a subset of active faults has been extracted based on geological evidence for fault activity at that time. Uncertainties of these age assignments are documented. The fault subsets delimit regions of different strain intensity. The superposition of strain intensity distributions across all time slices identifies regions affected by polyphase deformation and regions nearly undeformed over geological time, potentially indicating areas of increased or reduced present-day seismic hazard. Our new zonation consists of fewer regions than earlier ones. The geological zonation correlates well with recent seismicity in areas of Cenozoic rifting and reasonably well with less frequent earthquakes in a belt affected by Mesozoic extension and contraction. However, a few stronger earthquake cluster in regions of low geological strain. The most prominent earthquake clusters (Swabian Jura, Vogtland / NW Bohemia) also defy a simple correlation with known geological structures.

Description: poster

Description: poster

Description: As a result of the joint project ‘Subsurface Potentials for Storage and Economic Use in the North German Basin’ (German acronym: TUNB) the Geological Surveys of Northern Germany and the Federal Institute for Geosciences and Natural Resources (BGR) finalized a coherent geological 3D-model of the deep subsurface of the North German Basin in early 2021. The model consists of 13 major base surfaces from Oligocene to Zechstein, fault surfaces and hull surfaces of salt diapirs. In the northwestern part it is based on the datasets of the Tectonic Atlas of NW-Germany (GTA) along with well and seismic data from the hydrocarbon industry. Additionally to modelling the onshore part of Schleswig-Holstein and Hamburg and insuring cross-border consistency to the neighboring federal states, the Geological Survey of Schleswig-Holstein (LLUR) reconstructed a 3D-large-scale velocity model based on previous work from Jaritz et al. (1991). Their velocity approach was developed within the GTA-project and is based on sonic-log and check-shot-velocities. It assumes a linear velocity increase, which is calculated from specific global gradients for different major lithostratigraphic layers and laterally varying starting-velocities. To validate the constructed 3D-velocity-model, its velocities were compared to velocities measured at boreholes by oil and gas companies. In general, a good agreement was found between modeled and measured data (deviation 〈 5%), in which the average velocities seemed to resemble the check-shot data more accurately than the interval velocities the sonic-log-measurements. In distinct locations, the velocity model was used to convert the newly constructed TUNB-horizons from the depth- to the time-domain in order to compare them to seismic sections. Whereas overall a good agreement between horizons and seismic reflectors was found, differences were identified especially in structural complex areas. Whether these can be attributed to earlier interpretations from the GTA, the modelling of the horizons or insufficiencies in the velocity-model has yet to be determined. A follow-up project to the TUNB-project is anticipated to start in early summer 2021. The goal of the project is to derive a consistent velocity model over large parts of the North German Basin. Main challenges will be integrating available borehole and seismic data into existing velocity-modelling approaches with a special focus on establishing cross border consistency to eastern federal states.

Description: poster

Description: About 25% of the Earth’s mid-ocean ridges spread at ultraslow rates of less than 20 mm/yr. However, most of these ultraslow spreading ridges are located in geographically remote areas, which hamper investigation. Consequently, how the crust forms and ages at such spreading centres, which traditional models predict to be magma-starved and cold, remains poorly understood. One of the most accessible ultra-slow spreading centres is the Mid Cayman Spreading Centre (MCSC), in the Caribbean Sea, with spreading rates of ~15-17 mm/yr. CAYSEIS project was proposed to survey the Cayman Trough area in order to obtain new data that constraints the nature of the crust, tectonic structures, lithologies outcropping and hydrothermal processes taking place in this area. Understanding the sub-seabed geophysical structure of the MCSC is key to understanding not only the lithologies and structures exposed at the seabed, but more fundamentally, how they are related at depth and what role hydrothermal fluid flow plays in the geodynamics of ultraslow spreading. CAYSEIS was a joint and multidisciplinary programme of German, British and US American top tier scientists designed for the obtaining of a new high-quality dataset, including 3D Wide-Angle Seismic (WAS), magnetic, gravimetric and seismological data. During the CAYMAN project, we took leverage of the CAYSEIS dataset to invert a 3D tomographic model of the Cayman Trough lithosphere using the Tomo3D code (Meléndez et al., 2015; 2019). This is one of the first times that the Tomo3D code is used for 3D inversion of real datasets. Thus, we are checking our results comparing them with tomographic inversions of 2D lines and testing the different parameters to obtain the more accurate and higher resolution model as possible. The results of this experiment will show not only the lithospheric structure along and across the MSCS, including the exhumed Ocean Core Complexes in the surrounding areas, but the 3D lithospheric configuration of the region which is important to understand the crustal formation processes and the evolution of ultra-slow spreading settings.

Description: Poster

Description: poster

Description: The ongoing activity of Mount Etna and the proximity to the nearby population requires constant monitoring. Infrasound recordings play an important role in volcanic observation because explosive activity near or above ground as well as shallow tremor processes are easier to identify with airborne sound waves than with seismic waves that are significantly scattered and refracted in the volcano edifice. However, infrasound signals are often blurred by noise, in case of Mount Etna, mostly wind induced noise. manual distinction of noisy data from real volcanogenic signals brings along a considerable effort and requires expert knowledge. At Mount Etna five summit craters are currently known with fluctuating levels of activity. This leads to a wide variety of infrasound signal patterns interfered by changing noise levels. In order to distinguish waveforms of noise from signals of volcanic origin we apply unsupervised pattern recognition techniques. We show that by extracting features from the amplitude spectrum different infrasound regimes can be distinguished with Self-Organizing maps (SOMs). This technique provides an option to color-code the results for an intuitive interpretation and allows even for a more detailed recognition of transitional activity regimes. We create a reference data set from multiple months of infrasound waveforms to include as many activity regimes as possible to train the SOM. This enables a fast classification of new data.

Description: poster

Description: DFG FOR 2825

Description: poster

Description: poster

Description: Due to a complex interplay between the Earth and overlying ice sheets, a large variety of subglacial landforms developed. One example is the in the North German Basin widely spread phenomenon of tunnel valleys. An observed correlation to underlying salt structures is often explained mechanically. We focus on an alternative hypothesis based on thermodynamic processes: As salt better conducts heat than the surrounding rocks, the geothermal heat flux is augmented above salt structures. This leads to melting processes at the interface between the Earth and the ice sheet. The subglacial rivers finally erode the tunnel valleys. To test this hypothesis, we model related hydrothermal processes by means of a finite-difference open-source code (SHEMAT-Suit). The model accounts for heat conduction, groundwater flows, processes in the glaciothermal system such as the motion and spatiotemporal temperature evolution within the ice, and finally the coupling of both at the subglacial interface to account for the feedback mechanisms. Glaciothermal system and coupling processes are incorporated based on an idealized 1D model for the ice cover. We present a scaling analysis to discuss dominant processes. Our results show that a purely conductive subsurface (complete absence of groundwater flow) leads to a very moderate increase of the geothermal heat flux above salt structures. This implies a slight increase of the melting rates, which by itself is not enough to trigger tunnel valley erosion. Additional hydrothermal flows e.g. through fault zones may increase the subglacial melting rates. In this contribution, we will present results from a case study in the Southern North Sea. A 2D seismic section includes two tunnel valleys above salt structures. To model the state prior to erosion and sedimentation during and after the Quaternary glaciations, the Quaternary strata is replaced by strata with the same physical properties and thicknesses than the Paleocene to Miocene strata. Simulation runs with SHEMAT-Suite calculated the subsurface temperature distribution and the geothermal heat flux distribution at the subglacial interface. This allows assessing the subglacial melting rates along with the temperature profile within the ice cover for a number of glaciation scenarios. Current results show that thermodynamic processes reinforce the formation of tunnel valleys together with e.g. mechanical weakening by faulting.

Description: poster

Description: A combination of noninvasive geophysical magnetic gradiometery and electrical resistivity tomography (ERT) was employed to locate the remains of an old church form the 9th century in Neuss-Norf, Germany. The gradiometery survey was carried out along 27 parallel profiles oriented approximately E–W with a profile spacing of 1 m and a sampling spatial interval of 0.5 m along each profile in order to detect the distributions of the possible buried walls of the church and other related archaeological remains. The vertical gradient of the magnetic field, with a fixed distance of 1.04 m between the sensors, was measured. The lower sensor was fixed at a height of 0.32 m from the ground surface. The magnetic data were transferred to the frequency domain using Fast Fourier transform then reduced to the magnetic pole. The analytic signal and power spectrum techniques were applied to the obtained magnetic data. Moreover, ERT measurements were performed based on the results of the magnetic survey along 12 profiles utilizing the Wenner and Dipole-Dipole arrays with 0.5 m electrode spacing. The ERT data from both arrays were merged into one dataset to form a non-conventional mixed array. The ERT data were inverted into 2D resistivity models using robust (blocky) inversion technique, and then a 3D resistivity prospective was created. The combined interpretation of the magnetic and ERT showed that the archaeological structures are close to the ground surface with a maximum depth of up to 2 m. We successfully detected anomalous zones that could be associated with the walls of at least one ancient church-building in addition to several possible archaeological structures in the survey area. A considerable agreement between the results of both methods was observed. Highly magnetic sources that could be associated with metallic objects within tomb-like structures were detected. An archaeological map of the possible location of the old church and the assumed surrounding tombs and features was constructed. Finally, some promising places were suggested in order to start an archaeological excavation in the site based on the findings of our research.

Description: poster

Description: Geological maps are complex to produce through intensive and expensive field studies. Comparisons of geophysical data with geological conditions are difficult and often only qualitatively possible. The following work therefore examines an automated procedure to better reconcile this information. For this purpose, the terracing method, and a cluster analysis of potential field (gravity and magnetic field) and petrophysical data from the Karasjok and Ligurian Sea regions are used to interpret this geophysical measurements in a geological way. Two different tectonic regions were selected: (1) The Karasjok region is located in Northern Norway, where the Karasjok Greenstone Belt (KGB) dominates geological settings, consisting of abundant ultramafic intrusions, komatiites, gabbroic intrusions, amphibolites and migmatites. (2) The Ligurian-Provençal basin, part of the Western Mediterranean Sea, which is located between the French-Italian coastline and the island of Corsica. Geologically the area is characterised by the spreading zone in the Western Mediterranean. The high-resolution Airborne Gravity Gradient Survey and aeromagnetic datasets of the Karasjok region cover an area of 20 km x 30 km with a data resolution of 50 m. The dataset of the Ligurian basin cover a much larger area with the resolution of 5 km. Data constraints come from former LOBSTER and LISA campaigns and a study in the research group at CAU Kiel, new compilation of the AlpArray Gravity Research Group (AAGRG), besides data of the ICGEM Potsdam (disturbance) and the GOCE mission. By aid of the terracing algorithm, the boundaries of the anomalies are to be sharpened and regions with constant field amplitude were generated. For this purpose, a shape index-based algorithm was applied, which uses the shape index calculated at each field point to grade the function. Through an iterative process and the variation of parameters, the terracing result is refined. The resulting data sets are then further processed using a cluster analysis method. Here, the k-mean algorithm for domain classification is used to divide the geophysical measurement data into groups (cluster) of similar properties. The number of clusters k is specified and the data points are assigned to the respective clusters through an iterative process. Using the data of the datasets mentioned above the results of this applications are successfully compared with the corresponding geological maps of the two areas.

Description: Deutsche Forschungsgemeinschaft (DFG), SPP "MB-4D"

Description: https://doi.org/10.5880/fidgeo.2020.045 (Zahorec et al., 2021) via GFZ Data Services

Description: poster

Description: The German continental seismic reflection program DEKORP (DEutsches KOntinentales Reflexionsseismisches Programm) was carried out in the years between 1984 and 1999. The aim of DEKORP was to investigate the deep crustal structure of Germany with high-resolution near-vertical incidence (mostly vibro)seismic acquisition, supplemented by wide-angle seismic and other target-oriented piggy-back experiments, all complemented by optimized methods of data processing and interpretation. The DEKORP project was an equivalent to many other deep-seismic programs world-wide such as COCORP, BIRPS, LITHOPROBE, ECORS, CROP, BELCORP, IBERSEIS and others. The resulting DEKORP database consists of approximately 40 crustal-scale 2D-seismic reflection lines covering a total of ca. 4 700 km and one 3D-seismic survey covering ca. 400 km², recorded in close connection with the German Continental Deep Drilling Program (KTB). Nowadays, re-recording of these seismic traverses in the same extent and quality would often not be possible anymore due to increased acquisition costs and tightened permission requirements. Therefore these datasets provide unique and deep insights into the subsurface below Germany covering the earth’s crust from the surface to the upper mantle. Currently, many of the original raw data are still stored on old storage media and in formats, which can only be read by special devices, programs and experts. To prevent the final loss of this valuable geoscientific treasure an initiative at GFZ transcripts all relevant DEKORP data to modern formats and media. Over the last few years the demand for DEKORP data continuously increased. Several academic institutions and commercial companies reprocess and/or reinterpret these data, which lead to significant improvements in the quality of the results. Fields of applications are geothermal development, hazard analysis, hydrocarbon/shale gas exploration, underground gas storage, tunnel construction, disposal of nuclear waste and more. To simplify the data access for the scientific as well as for the commercial geo-community, a well-structured provision and utilisation concept is being developed. The concept includes so-called data publications with DOIs, a defined license model and automised retrieval for each of the surveys providing raw data, processed data, meta data, related links and more. The plan aims to have all relevant DEKORP datasets compiled and prepared for access via web interface till 2022.

Description: poster

Description: Aeromagnetic surveys help us to learn about geology. To achieve good coverage, surveys need to be merged. However, conventional methods introduce long-wavelength bias and cannot handle the individual survey quality. We develop a new approach to process large aeromagnetic surveys with an equivalent layer approach and combine them with satellite data. To facilitate the usage of large data sets, we divide the study area into blocks and treat each block individually. We adjust the block size according to the resolution of the equivalent source model. Within each block we solve for equivalent sources using an iterative linear inversion with Tikhonov regularization. We apply a multi-resolution strategy by iteratively decreasing the dipole spacing, dipole depth and block size. In each step, the resolution is applied to the residual of the previous steps. This ensures both a good representation of the large and small-scale structures as well as reasonable computational costs. Advantages of the blockwise inversion are the handling with large data sets due to splitting up the study area and neglecting influences of sources above a certain distance. This reduces computational costs and still fits the data well in comparison with an unblocked inversion. Some structures cannot be resolved well with just one dipole layer, so the multi-resolution strategy enables to have a better fit by separating regional and local sources. For the final compilation, we replace the long wavelengths part of the aeromagnetic data with satellite data to spherical harmonic degree 110. We demonstrate our new approach with a newly compiled large data base for Greenland.

Description: poster

Description: Recent years have shown an increased interest in Polar research and in particular in understanding tectonics and seismic hazard in the Arctic. To understand the seismic activity in the European Arctic, the seismic bulletins should be as complete as possible. We present a new seismic event bulletin for the European Arctic (70° – 90° N, -15° – 75° E), for the 24-year long period 1990 – 2013. The poster will show in detail the merging of the different sources taken in account for the compilation, the homogenization of the data and the relocation of the seismic events. With respect to the ISC bulletin for this region, the new bulletin contains 5,932 new seismic events and 54,630 new seismic onset readings from stations mostly located at regional distances. The gains are distributed over the entire study region, with the most significant contributions across the Svalbard Archipelago, along the Knipovich and northern Mohns Ridges, as well as northern Fennoscandia.

Description: Norwegian Research Council Grant 233973/H30

Description: Russian Foundation for Basic Research Grant 14-05-93080

Description: Russian Foundation for Basic Research Grant 18-05-70018

Description: https://doi.org/10.31905/TYLLQY8T

Description: poster

Description: During the last few years, the use of Ground-Penetrating-Radar (GPR) multi-channel antenna arrays in the Archaeological Prospection increased dramatically. The main advantage of this type of survey is a much faster data acquisition combined with a dense profile spacing. However, most of the common multi-channel arrays consist of antennae with a spacing of not smaller than 8 cm. The aim of our test survey was to evaluate how an even denser spacing of 4 cm that is provided by the IDS Stream-C GPR device at a centre frequency of 600 MHz can improve the detection of small archaeological features. As a test site, we chose the Great Bath in Kempten-Cambodunum. This first capital of the Roman province Rhaetia never has been overbuilt in the following centuries and even today it is used as a grassland declared as an Archaeological Park. Already in 1911, the Great Bath was excavated and beside the walls of different building phases, also small features like a multitude of hypocaust pillars were unearthed. Hence, this building structure depicts an ideal test site and a 40x40m grid covering the main part of the construction was chosen for the application of the antenna array. As a comparison, the same grid was contemporaneously surveyed with a single antenna IDS Duo device (600 and 200 MHz) and a 50 cm profile spacing. Regarding the walls of the Roman bath, the two surveys show comparable results: both datasets represent the stone constructions of 50 – 90 cm width quite well. Furthermore, the depth slices of both devices provide a differentiation of the single building phases. Nevertheless, the resolution for the multi-channel antenna array is of course much higher due to the denser profile spacing. Huger differences occur for the hypocaust pillars of 25 cm lateral length. These features can be mapped in detail with the 4 cm profile spacing of the IDS Stream-C system. Whereas the IDS Duo can only resolve some of the hypocausts, a multitude of them gets visible between 70 and 110 cm depth in the Stream-C data. As a conclusion, it can be stated that standard archaeological remains like stone walls, for sure, can be surveyed with single antenna GPR devices in a common profile spacing of 50 cm. However, in case of the existence of faint archaeological features the application of ultra-dense antenna arrays like the IDS Stream-C is advisable to get a comprehensive overview of a site without the necessity to excavate them.

Description: poster

Description: The Floodrisk project takes a muti- and interdisciplinary look on the effects of the rise in mine water level in abandoned coal mine regions in Germany. Such effects are heterogeneous ground uplift, stress changes due to the pore pressure changes and the reactivation potential of faults. One of the most directly measurable effects is the induced seismicity. It is known from previous studies that the flooding of old mines can lead to a renewed increase in induced microseismicity in these regions. We focused on the observation of the eastern Ruhr area and investigate in detail the relationship between mine water rise and induced seismicity in the Haus Aden dewatering area. For this purpose, we operate a network of up to 30 short period seismic stations in the region of the former "Bergwerk Ost" colliery, which had the highest seismicity rate in the Ruhr area during active mining. Continuous monitoring of seismicity and mine water levels is available for this region from the active mining phase, through the post-mining phase to flooding. Since the beginning of the flooding, more than 20000 onsets were picked and over 1700 induced events were localised in a magnitude range from -0.7 up to 2.6 MLv. For some larger events, focal mechanisms could be determined. The spatial distribution of hypocentres is divided into two areas, with few events in the central study area and over 95% of earthquakes in its eastern part. Many of these events are spatially clustered and some show quite high waveform similarity. This allows relative localisation to increase the accuracy of the location. Comparing the old galleries,which today serve as the main underground waterways, with the localisations from the relative localisation, strong correlations can be seen. The measured temporal trend of the mine water level, after pumps were shut down in mid-2019, shows a strong correlation with the temporal evolution of the observed micro seismicity. In the first months after the pumps are switched off, the water levels at the observation points rise only slowly and isolated microseismic events occur again. In November 2019, the rise in water levels doubled and at the same time, the strongest induced event in the measurement period was recorded with a magnitude of 2.6 MLv. In the years 2020, 2021 66 and 58 events 〉= MLv 1 were observed, respectively. In contrast to this number only 2- 9 events 〉= MLv 1 per year were observed in the post-minig phase before flooding.

Description: Bundesministerium für Bildung und Forschung

Description: poster

Description: In the last few years, several Unmanned Aerial Vehicle (UAV) based magnetometer systems have been tested for archaeological prospection. Due to their higher sensitivity, scalar magnetometers have been preferred as test sensors. However, total field magnetometer are vulnerable to disturbances, especially those generated by the UAV itself. Therefore, most UAV scalar magnetometer systems use the method of increasing the distance between magnetic sensors and the UAV to reduce interference. But freely suspended sensors tend to swing on ropes under the UAV and can produce data that are strongly influenced by heading errors. For our test, we therefore chose the UAV-fixed, compact setup of the SENSYS MagDrone R4, which is equipped with five three-axis FGM3D/75 fluxgate sensors at 50 cm spacing and is covering a swath width of 2.5 m. The 200Hz sampling rate of the R4 allows easy filtering of interference generated by the UAV and external disturbances like power lines or infrastructure. Magnetograms with a spatial resolution of up to 0.20 m per pixel were produced from the data. At Ganacker, we chose the former infrastructure core of the World War II German Air Force airfield as a test site. A wide range of archaeological structures and features with high magnetic contrast were expected on this area. The test site is currently an open agricultural area with a quite flat terrain. Hence, the R4 could be operated at a fixed flight height of just one metre above the surface of the terrain that is controlled actively by a radar sensor. An area of around 110 hectares were prospected within only four days. The MagDrone R4 system thus offers an outstanding survey area progress that cannot even reached by common vehicle-moved multi-sensor arrays. Here, we present the first results of this test survey by comparing the magnetograms, historical and current geodata. Most of the expected archaeological features and several unknown ones were detected by the R4 system. Our results show that the R4 system is well suited for mapping large archaeological structures with high magnetisations. In the future, we want to compare the R4 data with data from a ground-based fluxgate magnetometer. We also want to test whether the system is suitable for detecting archaeological features that have lower magnetic susceptibility and remanence contrasts with the surrounding soil.

Description: poster

Description: NEXD is an open source software package for the simulation of seismic waves in complex geological media. This includes elastic, viscoelastic, porous and fractured media with complex geometries. For the computation of the wave fields, the nodal discontinuous Galerkin approach (NDG) is used. The NDG approach combines unstructured tetrahedral meshes with an element-wise, high-order spatial interpolation of the wave field based on Lagrange polynomials. NEXD offers capabilities for modeling wave propagation in one-, two- and three-dimensional settings of very different spatial scale with little logistical overhead. It allows the import of external triangular (2D) and tetrahedral (3D) meshes provided by independent meshing software and can be run in a parallel computing environment. The computation of adjoint wavefields and an interface for the computation of waveform sensitivity kernels are offered. The method is verified by means of symmetry tests and the method of exact solutions. The capabilities of NEXD are demonstrated through, for example, a 2D synthetic survey of a geological carbon storage site. The most recent developments have been the inclusion of porous media in 2D and the inversion capabilities to the latest release versions of the 2D and 3D codes as well as the release of the 1D code. NEXD is available on GitHub: https://github.com/seismology-RUB.

Description: poster

Description: The ocean worlds of our Solar System, like Saturn's moon Enceladus and Jupiter's moon Europa are covered with ice. Recently, these icy moons gained further scientific interest, as they are attributed some potential to sustain or host extraterrestrial life in a subglacial ocean. The investigation of these moons will also help to understand the evolution of the Solar System. The in-situ exploration of these moons requires novel technological solutions as well as intelligent data acquisition and interpretation tools. In 2020, the DLR Space Administration started the TRIPLE project (Technologies for Rapid Ice Penetration and subglacial Lake Exploration) which develops an integrated concept for a melting probe that launches an autonomous underwater vehicle (nanoAUV) into a scientifically interesting water reservoir and an AstroBioLab for in-situ analysis. These three components build up the TRIPLE system. As part of a second project stage, it is envisioned to build the TRIPLE system and test it in Antarctica in 2026. In this contribution, we are going to present the general concept of TRIPLE with a focus on the geophysically most relevant aspects. To navigate the melting probe through the ice, a forefield reconnaissance system (TRIPLE-FRS) based on combined radar and sonar techniques is designed. This will include radar antennas directly integrated into the melting head combined with a pulse amplifier and a piezoelectric acoustic transducer just behind the melting head. In addition, an in-situ permittivity sensor will be implemented to account for the ice structure dependent propagation speed of electromagnetic waves. With this system, obstacles as well as the ice-water interface at the bottom of the icy shell could be detected. To deliver key parameters such as transit time and overall energy requirement, a virtual test bed for strategic mission planning is currently under development. This consists of the Ice Data Hub that combines available data from Earth or any other planetary body – measured or taken from the literature – and allows display, interpretation and export of data, as well as trajectory models for the melting probe. We develop high-fidelity thermal contact models for the phase change as well as macroscopic trajectory models that consider the thermodynamic melting process and the convective loss of heat via the melt-water flow.

Description: Bundesministerium für Wirtschaft und Energie (FKZ: 50NA1908, 50RK2050, 50RK2051, 50RK2052, 50RK2053)

Description: poster

Description: Deutsche Forschungsgemeinschaft

Description: poster

Description: Modelling the propagation of seismic waves in porous media gets more and more popular in the seismological community since it is an important but challenging task in the field of computational seismology. The fluid content of, for example, reservoir rocks or soils, and the interaction between the fluid and the rock or between different immiscible fluids has to be taken into account to accurately describe seismic wave propagation through such porous media. Often, numerical models are based on the elastic wave equation and some might include artificially introduced attenuation. This simplifies the problem but only approximates the true physics involved. Hence, the results are also simplified and could lack accuracy or miss phenomena in some applications. The aim of the conducted work was the consistent derivation of a theory for seismic wave propagation in porous media saturated by two immiscible fluids and the accompanying numerical solution for the derived wave equation. The theory is based on Biot's theory of poroelasticity. Starting from the basic conservation equations (energy, momentum, etc.) and generally accepted laws, the theory was derived using a macroscopic approach which demands that the wavelength is significantly larger than the size of the heterogeneities in the medium due to the size of the grains and pores or due to effects on the mesoscopic scale. This condition is usually fulfilled for seismic waves since the typical wavelength of seismic waves is in the order of 10 m to 10 km. Fluid flow is described by a Darcy type flow law and interactions between the fluids by means of capillary pressure curve models. In addition, consistent boundary conditions on interfaces between poroelastic media and elastic or acoustic media are derived from this poroelastic theory itself. The nodal discontinuous Galerkin method is used for the numerical modelling. The poroelastic solver is integrated into the 1D and 2D codes of the larger software package NEXD that uses the nodal discontinuous Galerkin method to solve wave equations. The implementation has been verified using symmetry tests and the method of exact solutions. This work has potential for applications in various scientific fields like, for example, exploration and monitoring of hydrocarbon or geothermal reservoirs as well as CO2 storage sites.

Description: poster

Description: Knowledge sharing in academia has been considered indispensable and is becoming a priority in most European funding schemes. Although we are already quite familiar with the different possibilities to publish our results in open-access journals, open science means way more than that. Open science aims at opening up research processes and granting access to research outputs to researchers, professionals and amateur scientists. There are different ways to ensure the storage and reusability of our data, making it available to other scientists. Furthermore, most of the scientific disciplines migrate their analyses to open-source environments (e.g., R, Phyton). However, tons of code produced remain stored in our personal computers either because we do not know the appropriate tools to share them with our colleagues or because we believe that it is not well structured. In this short course, you would learn how to establish links between publications, data, software and methods. Hence, we will discuss with our experts: i) the options to share our data and code with other peers, ii) obtain some tips to better organize our scripts, and iii) uncover potential barriers to sharing research and discuss possible solutions.

Description: DFG, SUB Göttingen, GFZ Potsdam

Description: presentation

Description: The rise of Open Science practices is impacting the entire scientific publishing culture. The transition to Open Access for text publications goes hand in hand with the growing demand to make scientific data and software available to the general public. The FAIR data principles play a key role in this, designed to make research and the underlying data easily findable, accessible, interoperable, and reusable for humans and machines. Geosciences data are as diverse as their content. They range from large real-time data streams of international observing networks to small data sets produced by individual researchers at their laboratories. Consequently, there need to be different strategies for data management and publication in which research data repositories can be important partners for the researchers. The Specialised Information Service for Geoscience (FID GEO) is a DFG-funded project that is promoting a holistic approach of Open Science that includes scholarly literature, data, samples, and scientific software equally and pushes for their interlinkage. FID GEO has become an important player for connecting researchers, data repositories, information infrastructures, German geoscientific societies, and publishers. FID GEO actively provides data and text publishing services through its affiliated repositories GFZ Data Services and GEO-LEOe-docs, as well as on-demand digitization of printed geoscience literature and maps. In addition, FID GEO aims to inform the German-based geoscience community about all aspects of Open Science and FAIR data by bringing the discussions to the individual disciplines through various communication channels.

Description: DFG, SUB Göttingen, GFZ Potsdam

Description: http://doi.org/10.5194/egusphere-egu22-13354

Description: presentation

Description: The rise of Open Science practices is impacting the entire scientific publishing culture. The transition to Open Access for text publications goes hand in hand with the growing demand to make scientific data and software available to the general public. The FAIR data principles play a key role in this, designed to make research and the underlying data easily findable, accessible, interoperable, and reusable for humans and machines. Geosciences data are as diverse as their content. They range from large real-time data streams of international observing networks to small data sets produced by individual researchers at their laboratories. Consequently, there need to be different strategies for data management and publication in which research data repositories can be important partners for the researchers. The Specialised Information Service for Geoscience (FID GEO) is a DFG-funded project that is promoting a holistic approach of Open Science that includes scholarly literature, data, samples, and scientific software equally and pushes for their interlinkage. FID GEO has become an important player for connecting researchers, data repositories, information infrastructures, German geoscientific societies, and publishers. FID GEO actively provides data and text publishing services through its affiliated repositories GFZ Data Services and GEO-LEOe-docs, as well as on-demand digitization of printed geoscience literature and maps. In addition, FID GEO aims to inform the German-based geoscience community about all aspects of Open Science and FAIR data by bringing the discussions to the individual disciplines through various communication channels.

Description: DFG, SUB Göttingen, GFZ Potsdam

Description: presentation

Description: FZ Data Services is a domain repository for geosciences data comprising the Earth, Space and Environmental Sciences. It assigns digital object identifier (DOI) to data and scientific software since 2004. Hosted at the GFZ German Research Centre for Geosciences (GFZ), the repository has a focus on the curation of long-tail data by domain scientists on one hand, but also provides DOI minting services for several global monitoring networks/observatories in geodesy and geophysics and collaborative projects. Furthermore, as Allocating Agent for the International Generic Sample Number (IGSN), the globally unique persistent identifier for physical samples, GFZ is providing IGSN minting services for physical samples. GFZ Data Services increases the interoperability of long-tail data through (1) the provision of comprehensive domain-specific data description via standardised and machine-readable metadata with controlled domain vocabularies. Metadata is (2) complemeted with comprehensive and standardised technical data descriptions or reports; and (3) by embedding the research data in wider context by providing cross-references through Persistent Identifiers (DOI, IGSN, ORCID, Fundref) to related research products (text, data, software) and people or institutions involved. In addition to the task as a research data publisher, GFZ Data Services is the central node for research data management at the GFZ with information on metadata, data formats, the data publication workflow, FAQ, links to different versions of our metadata editor and downloadable data description templates. Specific data publication guidance is complemented by more general information on data management, like a data management roadmap for PhD students.

Description: GFZ Potsdam

Description: presentation

Description: Open Access to scientific literature and research data has significant advantages for researchers as well as for society as a whole. Researchers might gain from increased citation rates and from higher visibility of their research outputs, while researchers as well as the public benefit from a better accessibility of scientific literature and data. Increasingly, funding organisations such as the European Commission in the context of Horizon 2020-funded projects or the 16 national and international members of “Plan S” demand that publications that result from projects funded by them are made openly accessible. The poster outlines the different ways of publishing text and data in Open Access. After a brief overview of reasons for publishing Open Access, it points out different routes for publishing texts in Open Access (in Open-Access-Journals or self-archiving) and major aspects for FAIR and open data publication.

Description: DFG, GFZ Potsdam

Description: poster

Description: The shift towards Open Science practices is increasingly demanded by science policy. The transition to Open Access for text publications goes hand in hand with a growing demand to make data, scientific software and samples, freely and FAIRly available to the general public. A persistent problem here is the clear and permanent accessibility and re-usability of scientific publications. This development affects both the scientific publication culture as well as the information infrastructures and poses major challenges to the German- based geosciences community. The specialized information service for geosciences (FID GEO) is a service funded by the German Research Foundation (DFG) and supports the cultural change towards Open Access publications. Hereby, FID GEO pursues a holistic approach to Open Science, including scientific literature, data, samples, and scientific software, and aims to promote their interconnection. FID GEO actively provides data and text publishing services through the affiliated repositories GFZ Data Services and GEO-LEOe-docs, as well as an on-demand digitization service of printed geoscientific literature and maps. The focus here is on the services and information systems that ensure permanently available and reliably citable publications of writings and data. Specifically, the service for text publications is provided in the FID GEOs own subject repository GEO-LEOe- docs. The affiliated research data repository GFZ Data Services is available for the publication of research data and scientific software from the earth and environmental sciences. In addition, FID GEO aims to comprehensively inform the German-based geoscientific community about Open Science and FAIR data by bringing the discussions to the individual disciplines through various communication channels. To strengthen the open information culture in the geosciences, FID GEO collaborates with strategic (inter)national initiatives such as NFDI4Earth, COPDESS and OneGeochemistry.

Description: DFG, SUB Göttingen, GFZ Potsdam

Description: poster

Description: i-EDDA-Research School (BGR Spandau); i-EDDA = Innovative Exploration Drilling and Data Acquisition, https://www.iedda.eu/ ; Datenmanagement Workshop: 05.11.2021

Description: DFG, GFZ Potsdam

Description: presentation

Description: The Berlin Declaration from 2003 was the starting point for Open Access to scholarly publications. Today, however, we speak about Open Science that reaches far beyond Open Access and represents collaborative, transparent and accessible research that includes all kinds of research results: scholarly literature, research data, software, samples, instruments, etc. In addition, efforts such as the FAIR Principles and the Enabling FAIR Data Commitment Statement, combined with increasing demands for machine accessibility to data, have raised user expectations towards the capabilities of research data repositories and datacentres. These repositories are often key partners supporting researchers in fulfilling the new requirements. This presentation will draw the line from major statements and requirements of Open Science, delineate the role of research data repositories as well as major research infrastructures, like the fNFDI4Earth or EPOS (European Plate Observing System) are additional players in making research data accessible in harmonised form.

Description: DFG, SUB Göttingen, GFZ Potsdam

Description: presentation

Description: How open is our research? A discussion on the state of Open Science in the field of mineralogy and petrology. Vortrag bei der Arbeitsgruppe Mineralogie+Petrologie der Uni Potsdam, 29.04.2022 A brief look at current trends toward an open science with a focused look at the state of the art in mineralogy and petrology. Followed by a discussion on how research in mineralogy and petrology can become more open.

Description: DFG, GFZ Potsdam

Description: presentation

Description: Dieser Band enthält 72 Beiträge zu Themengebieten der Physik der festen Erde, des magnetischen und elektrischen Felds der Erde, der Physik der Atmosphäre sowie der Angewandten Geophysik, veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in den Jahren 1928.

Description: 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0004.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0005.pdf"〉Gezeitenerscheinungen in der Atmosphäre〈/a〉〈br〉(Bartels, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0006.pdf"〉Erdmagnetische Säkularvariation und die Orientation alter Kultbauwerke〈/a〉〈br〉(Wehner, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0007.pdf"〉Über die Tiefenwirkung bei geoelektrischen Potentiallinienmethoden〈/a〉〈br〉(Hummel, J. N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0008.pdf"〉Überblick über den Gang der magnetischen Vermessung der Ostsee〈/a〉〈br〉(v. Gernet, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0009.pdf"〉Die Wirkung der Kontinente und Ozeane auf die Differenz 〈i〉B – A〈/i〉 der Hauptträgheitsmomente der Erde im Äquator〈/a〉〈br〉(Gutenberg, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0011.pdf"〉Bemerkungen zu H. v. Iherings Kritik der Theorien der Kontinentverschiebungen und der Polwanderungen〈/a〉〈br〉(Wegener, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0012.pdf"〉Berichtigung〈/a〉〈br〉(Jung, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0013.pdf"〉Illustration〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0014.pdf"〉Über die Polhöhenschwankungen infolge der Lorentz-Kontraktion der Erde〈/a〉〈br〉(Courvoisier, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0015.pdf"〉Zum Uhrvergleich auf drahtlosem Wege nach der Koinzidenzhörmethode〈/a〉〈br〉(Martin, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0016.pdf"〉Physikalische Grundlagen einer neuen geoelektrischen Aufschlußmethode〈/a〉〈br〉(Hummel, J. N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0017.pdf"〉Untersuchung der Potentialverteilung für einen speziellen Fall im Hinblick auf geoelektrische Potentiallinienverfahren〈/a〉〈br〉(Hummel, J. N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0018.pdf"〉Mächtigkeitsbestimmung von Deckschichten über Spalten durch Radioaktivitätsmessungen〈/a〉〈br〉(Koenigsberger, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0019.pdf"〉Zur Frage der regionalen, magnetischen Anomalien Deutschlands, insbesondere derjenigen Norddeutschlands〈/a〉〈br〉(Reich, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0021.pdf"〉Untersuchungen über die seismische Bodenunruhe kurzer Periode〈/a〉〈br〉(Schneider, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0022.pdf"〉Zur Theorie elektrischer Bodenforschung〈/a〉〈br〉(Heine, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0023.pdf"〉Emil Wiechert †〈/a〉〈br〉(Angenheister, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0024.pdf"〉Die topographische Reduktion bei Drehwagenbeobachtungen〈/a〉〈br〉(Numerov, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0025.pdf"〉Angewandte Seismik (Zusammenfassender Bericht über Arbeiten von 1921 bis 1928)〈/a〉〈br〉(v. Schmidt, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0027.pdf"〉Le problème des microséismes à groupes〈/a〉〈br〉(Gherzi, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0028.pdf"〉Zur Empfindlichkeitsbestimmung von magnetischen Variometern und zur Eichung der magnetischen Felder von Spulen〈/a〉〈br〉(Koenigsberger, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0029.pdf"〉Die Schrumpfungsgeschwindigkeit des Erdradius aus astronomischen Beobachtungen〈/a〉〈br〉(Meyermann, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0030.pdf"〉Über eine Verbindung zwischen den mondentägigen und den sonnentägigen Variationen der magnetischen Deklination〈/a〉〈br〉(Egedal, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0031.pdf"〉Die Zone der anormalen Hörbarkeit im kleinen〈/a〉〈br〉(Hiller, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0032.pdf"〉Mitteilungen〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0033.pdf"〉Ein graphisches Verfahren für Drehwagenmessungen zur Berechnung der Geländewirkung und der Wirkung beliebig gestalteter Massenkörper〈/a〉〈br〉(Haalck, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0035.pdf"〉Beiträge zur geoelektrischen Methode〈/a〉〈br〉(Hummel, J. N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0036.pdf"〉Zum Uhrvergleich auf drahtlosem Wege nach der Koinzidenzhörmethode〈/a〉〈br〉(Mahnkopf, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0037.pdf"〉Berichtigung〈/a〉〈br〉(Meyermann, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0038.pdf"〉Zur Frage nach der Ursache von lokalen gravimetrischen und erdmagnetischen Störungen und ihre wechselseitigen Beziehungen〈/a〉〈br〉(Haalck, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0040.pdf"〉Gemeinschaftliche Arbeit zwischen Seismologen und Baufachmann zur Verringerung von Erdbebenschäden〈/a〉〈br〉(Briske, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0042.pdf"〉Feldapparatur zur Registrierung von Zeitzeichen〈/a〉〈br〉(Köhler, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0043.pdf"〉Über die Schmidtsche Methode der Bestimmung der Parameter von Stabmagneten〈/a〉〈br〉(Bock, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0046.pdf"〉Referate der Vorträge auf der Tagung der Deutschen Geophysikalischen Gesellschaft in Hamburg vom 19. bis 21. September 1928〈/a〉〈br〉(Koenigsberger, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0048.pdf"〉Die Seismizität der Ozeane und Kontinente〈/a〉〈br〉(Tams, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0049.pdf"〉Bodenunruhe durch Brandung und durch Frost〈/a〉〈br〉(Gutenberg, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0050.pdf"〉Beitrag zur Schallausbreitung in der Atmospähre〈/a〉〈br〉(Kölzer, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0051.pdf"〉Das Magnetfeld einer elektrischen Strömung im anisotropen leitenden Halbraum〈/a〉〈br〉(Müller, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0052.pdf"〉Die geführten elastischen Zweimittel-Wellen〈/a〉〈br〉(Uller, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0053.pdf"〉Vom Jahre 1922 an im südlichen Norwegen aufgenommene Nordlichtphotogramme〈/a〉〈br〉(Störmer, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0055.pdf"〉Zur Frage nach der Ursache von lokalen gravimetrischen und erdmagnetischen Störungen und ihre wechselseitigen Beziehungen〈/a〉〈br〉(Haalck, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0057.pdf"〉Vorträge, gehalten auf der Tagung der Deutschen Geophysikalischen Gesellschaft vom 19. bis 21. September 1928〈/a〉〈br〉(Seilkopf, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0060.pdf"〉Statistische Mechanik der Atmosphäre〈/a〉〈br〉(Baur, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0061.pdf"〉Das Schwadorfer Beben vom 8. Oktober 1927〈/a〉〈br〉(Conrad, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0062.pdf"〉Das Periodogramm der internationalen erdmagnetischen Charakterzahlen〈/a〉〈br〉(Wenzel Pollak, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0064.pdf"〉Der Stand der erdmagnetischen Forschung〈/a〉〈br〉(Schmidt, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0065.pdf"〉Magnetische Anomalien im westlichen Mecklenburg〈/a〉〈br〉(Schuh, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0066.pdf"〉Bemerkungen zur numerischen und graphischen Behandlung der Krümmungsgröße〈/a〉〈br〉(Jung, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0067.pdf"〉Der Wasserhaushalt der Antarktis in der Eiszeit〈/a〉〈br〉(Meinardus, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0068.pdf"〉Übersicht über Neuerscheinungen〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0069.pdf"〉Vortrage, gehalten auf der Tagung der Deutschen Geophysikalischen Gesellschaft vom 19. bis 21. September 1928〈/a〉〈br〉(Tams, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0071.pdf"〉Über kartographische Darstellung der Seismizität〈/a〉〈br〉(Renquist, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0072.pdf"〉Ergebnisse von Pilotaufstiegen im Gebiete von Island〈/a〉〈br〉(Georgi, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0073.pdf"〉Referat über die Polarfront- und Äquatorialfronttheorien〈/a〉〈br〉(Stüve, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0074.pdf"〉Die Messung der Horizontal- und der Vertikalintensität mit dem Magnetron〈/a〉〈br〉(Rössiger, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0075.pdf"〉Untersuchungen über die lokalen Schwankungen des Erdpotentials〈/a〉〈br〉(Stoppel, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0076.pdf"〉Klima und Klimatafel von Hamburg〈/a〉〈br〉(Perlewitz, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0077.pdf"〉Neue Ergebnisse über die Struktur des Windes (Vorläufige Mitteilung)〈/a〉〈br〉(Schmidt, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0079.pdf"〉Lokale und regionale magnetische Anomalien in Schleswig-Holstein〈/a〉〈br〉(Reich, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0080.pdf"〉Die optische Station in Simferopol〈/a〉〈br〉(Tichanowsky, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0081.pdf"〉Das Strömungssystem der Luft über dem tropischen Atlantischen Ozean nach den Höhenwindmessungen der Meteor-Expedition〈/a〉〈br〉(Kuhlbrodt, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0082.pdf"〉Ergebnisse und Aufgaben der meteorologischen Strahlungsmessungen〈/a〉〈br〉(Süring, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0083.pdf"〉Ergebnisse von Drehwaagemessungen in Schlewig-Holstein〈/a〉〈br〉(Jung, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0085.pdf"〉Aufsätze〈/a〉〈br〉(Lotze, F., Brockamp, B., Haalck, H., Myrbach, O., Whipple, Cabannes, J., Dufay, J., Gherzi, E., Pochettino, A., Rostagni, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0096.pdf"〉Mitteilungen〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0097.pdf"〉Autorenverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0098.pdf"〉Sachverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0099.pdf"〉Literaturverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0100.pdf"〉Geophysikalische Berichte〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0004/LOG_0101.pdf"〉Register der Goephysikalische Berichte〈/a〉〈/li〉 〈/body〉 〈/html〉

Description: research

Description: DGG, DFG, SUB Göttingen

Description: In der vorliegenden Arbeit wird die Krustenstruktur im östlichen Andenvorland untersucht. Das Gebiet umfaßt den Nordwesten Argentiniens, zwischen dem 22° und 25° südlichen Breitengrad und dem 66° und 62° westlichen Längengrad. Aus morphologischer Sicht befindet sich das Untersuchungsgebiet im Übergang zwischen dem Subandin (Sierras Subandinas) und der südlichen Ostkordillere zum Chaco Vorland (Llanura Chaqueña). Im Untersuchungsgebiet zeichnet sich ein Wechsel in den tektonischen Strukturen ab, welcher als Interaktion zwischen der tertiären Andenorogenese und kretazischen Riftbildungen gedeutet wird. Dieser als Inversionstektonik bekannte tektonischer Stil hat nicht nur oberflächennahe Strukturen hervorgerufen, sondern auch tiefgreifende Massenveränderungen verursacht. Teile dieser Modifikationen sind in der Signatur des Schwerefeldes erhalten geblieben, und somit ist die Interpretation gravimetrischer Meßergebnisse zusammen mit den geologischen Randbedingungen eine Grundvorraussetzung zur Untersuchung dieser tektonischen Interaktion. Zum Verständnis dieser Strukturen war es notwendig, sowohl den Teil des Beckens zu untersuchen, welcher nicht von der andinen Orogenese betroffen ist, als auch jenen der direkt in die letztere miteinbezogen wurde. Aus gravimetrischer Sicht ist die Bougueranomalie des Gebietes stark vom Effekt der Andenwurzel geprägt. Jedoch deuten einige Abweichungen auf die Existenz lokalerer Störkörper hin, die Ziel der Modellierung waren. Ein solcher Störkörper wurde am südöstlichen Rand des kretazischen Rifts identifiziert. Die Modellierung wurde einerseits zweidimensional durchgeführt um einen Überblick über das Gebiet zu bekommen. Eine regionale 3D Modellierung führte dann zu einer präziseren Interpretation des Gebietes. Insbesondere wurde dabei der Effekt überschobener Riftschollen am Ostrand des Beckens untersucht. Diese Überschiebungen drücken sich im gravimetrischen Restfeld als deutliche positive Anomalie aus. Allerdings kann diese Anomalie nicht direkt mit einem Astenosphärenanstieg, welcher durch Riftbildung entstanden sein könnte, in Einklang gebracht werden - wie von einigen Autoren vermutet wurde. Eine weitere modellierte Struktur bildete die Vortiefe, welche durch die Auflast der andinen Überschiebung enstanden ist. Die dadurch hervorgerufenen negativen Anomalien bilden einen deutlichen Kontrast zu der beschriebenen positiven Anomalie im Vorland, der sich auch im Restfeld als starker Gradient äußert. Die 2D Modellierung erbrachte folgende Ergebnisse: im anorogenen Breich des Untersuchungsgebietes wurde die Existenz einer deutliche Asymmetrie des Beckens bestätigt, mit einer nach Südosten geneigten Riftabscherungsfläche. Die Orogenese hinterließ deutliche Spuren in der Reaktivierung der Abscherungen wobei entlang der südostvergenten Störungen tieferes Krustenmaterial emporgeschoben wurde. Mit einer größeren Dichte wird dieser Vorgang als Ursache der positiven Anomalie intepretiert. Westvergente Störungen scheinen nur oberflächennahe Bereiche miteinbezogen haben. Im regionalen 3D Modell wurde ein Ansteigen der Unterkruste unterhalb des Beckens angenommen. Die asymmetrische Anordnung dieses Anstiegs deutet eher auf einen kompressive tektonischen Effekt hin als auf eine residuale Krustenverdünnung. Zusammenfassend kann gesagt werden, daß sich in diesem Breich im Schwerefeld die Effekte des Andengradienten mit denen der überschobenen Basement-Tektonik und der Vorlandtief kombinieren und als solche fur einen starken lokalen Gradienten am Rande des Effekts der Andenwurzel verantwortlich sind.

Description: In the present study, the structure of the crust beneath the eastern Andean foreland is analyzed. The area comprises part of northwest Argentina, between 22° and 25° S and 66° and 62° W. In terms of morphotectonics, the area studied covers the transition between the Sierras Subandinas (Subandean Ranges) and the southern part of the Cordillera Oriental (Eastern Cordillera) to the Chaco plains (Llanura Chaqueña). In the area, a pervasive change controls the tectonic features, which is interpreted as a consequence of the interaction between the Andean orogeny and preexistent Cretaceous rifting. This inversion tectonics did not only result in a particular suite of near to surface structures but also modified deeply the mass distribution within the crust. This changes in mass distributions and hence density contrasts is evidenced by the gravity field. As such, a careful analysis of gravity data together with the geological boundary conditions are the basis for an analysis of this tectonic interaction. Understanding these structures implied to analyse not only the part of the rift involved in the Andean compressive orogenesis but also that part where original extensional features are still preserved. From a gravimetrical point of view, the Bouguer-anomaly of the area shows a strong overprint related with the Andean root. Some smaller changes in the field however indicate the existence of local sources, which where the target of the modelling. Such a change had been indentified at the southeastern edge of the Cretaceous rift. Modelling was performed towfold. As such, a 2D model was made in order to get an insight into the regional aspects of the area. A more detailed 3D model led to a more precise interpretation of the area. In particular, the effect of the inverted rift tectonics at the eastern edge of the basin was studied. These upthrusts correlate with a readily identifiable positive anomaly within the residual field. The anomaly neverthless cannot be directly related with an astenospheric uprise, preserved since the rifting stage, as suggested by some authors. In addition, the foredeep related with the tectonic load of the Andean overthurst, was modelled. The negative anomalies generated during this process, show a strong contrast in comparison with the positive anomaly described above, depicted also by a prominent gradient in the residual field. 2D modelling led to the following results. In the region, where Creataceous rifting structures were not overprinted by the Andean orogeny an obvious asymmetry of the basin was defined, being the master detachment dipping to the northeast. The orogeny left evidences of reactivation, where the structures of the southeastern edge were the pathways of the uplift if deeper crustal material with a higher density. This process may be responsible for a part of the positive anomaly mentioned. Structures located at the western and northwestern edge of the basin seem to have only involved nearer-to surface structures. The 3D model assumed a slight uprise of the lower crust beneath the basin. The asymmetry in goemetty seem to stand more for a tectonic effect than for a remanent thinned crust. As a summary, the gravity field in this area shows the combined effects of the regional Andean gradient with the more local effects of the basement tectonics (inverted rifting) and the overthrusted foredeep. Hence, at least these three factors seem to be responsible for the strong local gradient in a lateral position of the Andean root.

Description: thesis

Description: DFG, SUB Göttingen