Leibniz Institute For Angewandte Geophysik

Hannover, Germany

Leibniz Institute For Angewandte Geophysik

Hannover, Germany

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Karle M.,Niedersachsisches Institute For Historische Kustenforschung | Karle M.,Senckenberg Institute | Frechen M.,Leibniz Institute For Angewandte Geophysik | Wehrmann A.,Senckenberg Institute
Zeitschrift der Deutschen Gesellschaft fur Geowissenschaften | Year: 2017

The climatic changes in the Late Quaternary have led to a series of environmental changes in the coastal area of the southern North Sea. The Pleistocene landscape around the Jade Bay was gradually inundated and covered with Holocene coastal deposits during sea-level rise after the Last Glacial Maximum (LGM). In this context, a data base of 827 core logs and 8 piston cores was interpreted with regard to lithological indicators of environmental changes south of the modern Jade Bay. By the sedimentological and stratigraphical analysis of ancient extended salt marsh belts, silting-up zones and tidal flat / tidal channel complexes, the position, internal structure and extension of the land-sea interface was reconstructed in detail giving insight into principle processes and interactions taking place in this highly sensitive zone during sea-level changes. The Holocene coastal sediment sequence in the Jade area consists of four distinct lithological units representing semiterrestrial, brackish-lagoonal and shallow marine sub-environments. With regard to small scale sea-level fluctuations in the latest phase of the Holocene transgression, distinct periods of stagnation or even regression occurred. In contrast to the typical internal composition of the Holocene deposits of the backbarrier coast with a multiple alternation of landward and seaward facies shifts, indicating repeated shoreline displacements, the Holocene sequence of the Jade Bay is characterised by only one landward-seaward facies shift. However, the sedimentary record is displayed in complex sequences of clastic deposits of tidal flat and brackish environments and intercalated beds of autochthonous fen and raised bog peat. From 11thcentury, onward increasing human activity has significantly influenced the development of the coastal landscape by dike construction, dewatering and land reclamation along the entire coastline. Consequently, the former swamptype characteristic of the extended lower supratidal zone has significantly changed into a narrow belt of salt marshes restricted by an artificially fixed coastline and the decoupling of marine-terrestrial processes. In the light of recent regional sea-level curve discussions, the presence of sea-level index points is critically discussed, due to the widespread existence of thick peat beds. © 2017 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany.

Schmitt D.R.,University of Alberta | Wilson T.J.,Ohio State University | Jarrard R.D.,University of Utah | Paulsen T.S.,University of Wisconsin - Oshkosh | And 3 more authors.
46th US Rock Mechanics / Geomechanics Symposium 2012 | Year: 2012

A set of hydraulic fracturing stress measurements were carried at depths of up to 1400 m below the rig floor at the bottom of the ANDRILL South McMurdo Sound borehole. The measurements were accomplished in open hole through indurated and low permeability glacial diamicts and shales. A 2000-m long wireline hosted straddle packer system was used that allowed for relatively rapid deployment; and seventeen successful measurements were made. Good breakdown pressures were observed in most of the tests; and this allowed constraints to be placed on the magnitude of the greatest horizontal compression. Correspondingly, the vertical stress was calculated by integrating the densities obtained from physical property logging of the nearly continuous core. In all cases, this vertical stress magnitude was intermediate between the horizontal stress values, and consequently indicating a strike-slip stress environment exists at this location. Copyright 2012 ARMA, American Rock Mechanics Association.

Diez A.,Alfred Wegener Institute for Polar and Marine Research | Diez A.,Karlsruhe Institute of Technology | Eisen O.,Alfred Wegener Institute for Polar and Marine Research | Eisen O.,University of Heidelberg | And 3 more authors.
Annals of Glaciology | Year: 2013

Two seismic surveys were carried out on the high-altitude glacier saddle, Colle Gnifetti, Monte Rosa, Italy/Switzerland. Explosive and vibroseismic sources were tested to explore the best way to generate seismic waves to deduce shallow and intermediate properties (<100 m) of firn and ice. The explosive source (SISSY) excites strong surface and diving waves, degrading data quality for processing; no englacial reflections besides the noisy bed reflector are visible. However, the strong diving waves are analyzed to derive the density distribution of the firn pack, yielding results similar to a nearby ice core. The vibrator source (ElViS), used in both P-and SH-wave modes, produces detectable laterally coherent reflections within the firn and ice column.We compare these with ice-core and radar data. The SH-wave data are particularly useful in providing detailed, high-resolution information on firn and ice stratigraphy. Our analyses demonstrate the potential of seismic methods to determine physical properties of firn and ice, particularly density and potentially also crystal-orientation fabric.

Diez A.,Alfred Wegener Institute for Polar and Marine Research | Diez A.,Karlsruhe Institute of Technology | Eisen O.,Alfred Wegener Institute for Polar and Marine Research | Eisen O.,University of Heidelberg | And 7 more authors.
Annals of Glaciology | Year: 2014

In 2010 a reflection seismic survey was carried out on the Alpine glacier Colle Gnifetti. The processed and depth-converted data could be compared to a nearby ice core, drilled almost to the bed. Comparisons showed that the depth of the P-wave bed reflection was too shallow, while the depth of the SH-wave bed reflection fitted the ice-core length well. We are now able to explain the major part of these differences using the existing crystal orientations of the ice at Colle Gnifetti. We calculate anisotropic velocities for P- and SH-waves that are usually picked for stacking and compare them with zero-offset velocities needed for the depth conversion. Here we take the firn pack at Colle Gnifetti into account for P- and S-wave analysis. To incorporate the S-wave analysis we first derive a new equation for the relationship between density and S-wave velocity from diving waves. We show that anisotropic fabrics observed at Colle Gnifetti introduce a difference of only 1% between stacking and depthconversion velocities for the SH-wave, but 7% for the P-wave. We suggest that this difference in stacking and depth-conversion velocity for the P-wave can be used to derive information about the existing anisotropy by combining our seismic data with, for example, radar data.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2008.5.2.4 | Award Amount: 10.56M | Year: 2009

The objectives of MUSTANG are to develop and disseminate a comprehensive set of methodologies and tools for the assessment and characterization of deep saline aquifers for CO2 storage, providing measures of performance and risk that are necessary for a cost-benefit analysis, ensuring public confidence and acceptance and promoting its deployment. Novel CO2 storage specific field investigation technologies and methodologies will be developed, allowing an improved determination of the relevant physical properties of the site and enabling short response times in the detection and monitoring of CO2 plumes during both the injection and storage phases. We also aim at an improved understanding of the processes of CO2 spreading by means of theoretical investigations, laboratory experiments, natural analogue studies and field scale injection tests, including those relevant to the 1) seal integrity; 2) the negative impact of possibly conductive faults; 3) formation heterogeneities; 4) CO2 trapping mechanisms; and 5) effective treatment for the wide span of spatial and temporal scales of the coupled thermo-hydro-mechanical-chemical processes. Based on the improved process models, conceptual and numerical models will be developed for analyzing CO2 injection and storage and implemented at six test sites representing different geological settings and geographical locations in Europe, also addressing the impact of the CO2 injection on seal integrity. The guidelines to be developed will be integrated into a decision support system, which will include a risk assessment component and liabilities consideration. The DSS will be tested and validated at the various project test sites. Special attention has been devoted to promote measures capable of enhancing public outreach and acceptance and dissemination of the methodologies and technologies to the wide public.

Weller A.,Clausthal University of Technology | Zhang Z.,Southwest Petroleum University | Slater L.,Rutgers University | Kruschwitz S.,BAM Federal Institute of Materials Research and Testing | Halisch M.,Leibniz Institute For Angewandte Geophysik
Geophysics | Year: 2016

Permeability estimation from induced polarization (IP) measurements is based on a fundamental premise that the characteristic relaxation time τ is related to the effective hydraulic radius reff controlling fluid flow. The approach requires a reliable estimate of the diffusion coefficient of the ions in the electrical double layer. Others have assumed a value for the diffusion coefficient, or postulated different values for clay versus clay-free rocks. We have examined the link between a widely used single estimate of τ and reff for an extensive database of sandstone samples, in which mercury porosimetry data confirm that reff is reliably determined from a modification of the Hagen-Poiseuille equation assuming that the electrical tortuosity is equal to the hydraulic tortuosity. Our database does not support the existence of one or two distinct representative diffusion coefficients but instead demonstrates strong evidence for six orders of magnitude of variation in an apparent diffusion coefficient that is well-correlated with reff and the specific surface area per unit pore volume Spor. Two scenarios can explain our findings: (1) the length scale defined by τ is not equal to reff and is likely much longer due to the control of pore-surface roughness or (2) the range of diffusion coefficients is large and likely determined by the relative proportions of the different minerals (e.g., silica and clays) making up the rock. In either case, the estimation of reff (and hence permeability) is inherently uncertain from a single characteristic IP relaxation time as considered in this study. © 2016 Society of Exploration Geophysicists.

Dahm T.,University of Hamburg | Kuhn D.,NORSAR | Ohrnberger M.,University of Potsdam | Kroger J.,Geologisches Landesamt Hamburg | And 4 more authors.
Geophysical Journal International | Year: 2010

Shallowly situated evaporites in built-up areas are of relevance for urban and cultural development and hydrological regulation. The hazard of sinkholes, subrosion depressions and gypsum karst is often difficult to evaluate and may quickly change with anthropogenic influence. The geophysical exploration of evaporites in metropolitan areas is often not feasible with active industrial techniques.We collect and combine different passive geophysical data as microgravity, ambient vibrations, deformation and hydrological information to study the roof morphology of shallow evaporites beneath Hamburg, Northern Germany. The application of a novel gravity inversion technique leads to a 3-D depth model of the salt diapir under study. We compare the gravity-based depth model to pseudo-depths from H/V measurements and depth estimates from small-scale seismological array data. While the general range and trend of the diapir roof is consistent, a few anomalous regions are identified where H/V pseudo-depths indicate shallower structures not observed in gravity or array data. These are interpreted by shallow residual caprock floaters and zones of increased porosity.The shallow salt structure clearly correlates with a relative subsidence in the order of 2 mm yr -1. The combined interpretation of roof morphology, yearly subsidence rates, chemical analyses of groundwater and of hydraulic head in aquifers indicates that the salt diapir beneath Hamburg is subject to significant ongoing dissolution that may possibly affect subrosion depressions, sinkhole distribution and land usage.The combined analysis of passive geophysical data may be exemplary for the study of shallow evaporites beneath other urban areas. © 2010 The Authors Journal compilation © 2010 RAS.

Hoecht G.,DMT Petrologic GmbH | Rost F.,DMT Petrologic GmbH | Luschen E.,Leibniz Institute For Angewandte Geophysik
76th European Association of Geoscientists and Engineers Conference and Exhibition 2014: Experience the Energy - Incorporating SPE EUROPEC 2014 | Year: 2014

In common-reflection-surface (CRS) imaging the data space is parameterized by operators that are expected to overlap in a continuous manner along events in the image space. These circumstances are employed in the operator-oriented scheme which integrates neighboring operators and, thereby, introduces multiple operators in the stacking process. Azimuth-dependant stacking velocities allow to account for a general type of model and are included in the hyperbolic CRS formula. We demonstrate the application of the operator-oriented CRS stacking method and the impact of azimuth-dependant stacking velocities in the context of a 3D WAZ land data set acquired over a crystalline basement.

Kuhn P.,University of Tübingen | Techmer A.,Leibniz Institute For Angewandte Geophysik | Weidenfeller M.,Landesamt fur Geologie und Bergbau Rheinland Pfalz
Quaternary Science Reviews | Year: 2013

Lower to middle Weichselian loess, loess derivatives and buried soils of the loess-paleosol sequence Alsheim (Central Europe) were characterised by particle size distribution, geochemical and micromorphological data. High rates of sedimentation with alternating phases of relocation are the main cause for a much less differentiation into Middle and Upper Weichselian loess-paleosol units of the Alsheim loess-paleosol sequence compared to other loess-paleosol sequences (e.g. Nussloch near Heidelberg), whereas the Lower Weichselian has distinct phases of pedogenesis resulting in Ah, Bw and Btw horizons.To distinguish between different loess deposits locally and intraregional, the degree of fineness is an easily applicable and suitable tool, though inappropriate for interregional comparisons. The chemical index of alteration (CIA) is low (<50=no weathering) for loess deposits in the Alsheim loess-paleosol sequence, which is in contrast to the worldwide compiled loess samples with CIA values ranging from >53 to <70 (Gallet etal., 1998). The highest weathering was detectable for Btw horizons with CIA values >70.A direct quantitative estimation of mean annual palaeotemperature and mean annual palaeoprecipitation can be provided by calculations based on geochemistry of soil horizons and sediments. The present mean annual precipitation (MAP) in the Mainz Basin is 789mm. In contrast, palaeoprecipitation data suggest a 150mm higher amount for the Last Interglacial (Btw horizon), a much lower amount of around 300-400mm MAPP (periods of loess and sandy loess deposition) and a MAPP of <500mm for Weichselian Interstadials (humus zones and Bw horizons). The calculated mean annual palaeotemperature (MAPT) for Interstadials with 8.9°C for Bw horizons or with 9.6°C for humus zones (or to 2K lower, considering the relation of the present MAT of the Mainz Basin with the MAT of Germany) seems to be a good approximation of the MAPT for Lower and Middle Weichselian Interstadials. A MAPT of 8.7°C (or 6.7°C) for Stadials (loess and sandy loess samples) is higher than other temperature estimations for Weichselian Stadials in Europe.Micromorphology shows compacted granular structure and moderately to strongly developed pedality as characteristic properties for aquatic loess, whereas channel microstructure with no pedality is typical for loess deposits. Spongy microstructure suggests a classification of the Lower Weichselian Mosbach Humus Zones as Chernozems. The Eemian paleosol (Btw horizon in Als III) has only weak clay illuviation, characteristic for drier regions in Europe.Palaeoclimate and soil formation of the Last Glacial-Interglacial cycle calculated from geochemistry and micromorphological data are in good accordance with other proxy data in Central Europe. This suggests that paleoclimate reconstruction based on palaeopedological analyses could be successfully implemented in Europe. Such data may provide a useful alternative to other proxies for correlating European records. © 2013 Elsevier Ltd.

Stober I.,Regierungsprasidium Freiburg | Jodocy M.,Regierungsprasidium Freiburg | Schellschmidt R.,Leibniz Institute For Angewandte Geophysik | Schulz R.,Leibniz Institute For Angewandte Geophysik
Zeitschrift der Deutschen Gesellschaft fur Geowissenschaften | Year: 2013

The prediction of the subsurface temperature is most relevant for the development of geothermal resources for energy use. This study presents an estimate of the subsurface temperature distribution in Baden-Württemberg on the basis of temperature measurements. There are many temperature data sets of the Upper Rhine Graben and the Molasse Basin in southern Germany resulting from extensive hydrocarbon exploration. However, temperature predictions remain difficult if data are scarce or local up- or down-welling of water disturbs the temperature distribution. In this study we investigated and digitised further analogue records of hydrocarbon wells and groundwater captures. Based on this expanded database, we developed a geostatistical temperature model by applying 3D kriging algorithms. The new 3D temperature model has a resolution of 2000 m in lateral direction and 100 m in vertical direction. In the future this spatial grid of temperature estimates can be used for identifying the geothermal potential of geologic formations. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

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