Northwest German Basin Research Articles

Lower Jurassic (Pliensbachian–Toarcian) marine paleoenvironment in Western Europe: sedimentology, geochemistry and organic petrology of the wells Mainzholzen and Wickensen, Hils Syncline, Lower Saxony Basin

AbstractOver the past few decades, Toarcian (Early Jurassic) black shale deposits of NW Europe have been extensively studied, and the possible global and regional mechanisms for their regional variation have been discussed. In this context, the black shales of the Northwest German Basin are still sparsely studied with regard to their palaeo-depositional history. This study aims to understand the connection between regional and global influences on the widespread Early Toarcian oceanic anoxic event by examining two wells covering the Upper Pliensbachian to Upper Toarcian sediments in the Northwestern German Basin. The core intervals were analysed using a multidisciplinary approach, including geochemistry, biostratigraphy and organic petrography. Marine palaeoenvironmental changes were reconstructed, and sediment sequences were stratigraphically classified to allow a supra-regional stratigraphic correlation. The results reveal complex interactions between sea level changes, climate warming, basin confinement, and Tethys–Arctic connectivity resulting in the Toarcian black shale deposition. Upper Pliensbachian sediments were deposited under terrigenous influence, shallow water depths, and predominantly oxic bottom water conditions. The deposition of black shale is characterized by algal organic material input and anoxic bottom water conditions. Strong correlations between water stratification, anoxia, and bioproductivity suggest that global warming and intensification of monsoonal rainfall, continental weathering, and increasing freshwater and nutrient inputs were the main factors controlling the formation of black shales. Prolonged deposition of OM-rich sediments in the NWGB may be related to intensified monsoonal precipitation in northern Europe and enhanced Tethys–Arctic connectivity at the serpentinum–bifrons transition. Graphical Abstract

Inversion of potential fields by interactive optimization of 3D subsurface models using a spring-based space warping and evolution strategy

The rapid development of dynamic data-integrative modeling of geologic processes and subsurface structures is an important factor for the sustainable utilization of natural resources. One of the current gaps in data-integrative modeling is the interactive construction of realistic 3D models of the earth’s underground. We have developed here a methodology of 3D interactive processing of potential fields — gravity and magnetics — as well as their potentials and derivatives, combining forward and inverse modeling. Forward computations are based on the approximation of geologic subsurface structures by polyhedra with triangulated surfaces. Inverse computations for the model geometry are performed by means of the covariance matrix adaptation evolution strategy (CMA-ES), which is proved to be efficient in the case of a strongly nonlinear problem and high-dimensional parameter space, as in potential field models. The main disadvantage is related to triangulation, as certain algorithmic constraints must be applied during the approximation of geologic body shapes. To avoid topology distortions, we use a concept of warping the space containing the model, rather than the model itself. However, the optimized lengths of grid sides are dependent on each other, which degrades the self-adaptation of the CMA-ES. The elegant solution is to introduce a system of virtual elastic springs connecting the grid nodes. We develop a numerical formulation of this system and provide a proof of the concept rather than an overview of the theoretical concepts of the inversion schemes. The new workflow is tested on the 3D SEG Advanced Modeling Program model and applied to a real case study of salt dome modeling in the Northwest German Basin. In the context of the inversion procedure described here, we determine how an interpreter can visually control and influence the quality of the inversion on a timeline.

Determination of Hydraulic Properties of a Large Self-Propped Hydraulic Fracture in the Geothermal Research Borehole Horstberg Z1 in the Northwest German Basin

The pressure records of an interference test on a huge hydraulic fracture in a layered sedimentary rock formation of the Northwest German Basin were analysed in order to determine fracture transmissivity and fracture storage coefficient. The fracture had been created by injecting some 20,000 m3 of freshwater at 3800 m depth in borehole Horstberg Z1 of the geothermal research project GeneSys. Its main purpose is to study the hydraulic properties and mechanical behaviour of artificial fractures kept open by the so called self-propping effect which results from the misfit of the opposite fracture surfaces being sheared during fracture propagation. A diagnosis of the pressure records of the interference test showed that the flow geometry is parallel (vertical linear fracture flow) rather than radial or bilinear. This is explained by assuming a highly conductive flow channel within the fracture resulting from a turn of tensile to mixed-mode fracture propagation. Based on this observation an analytical 1D-model was developed that describes transient fluid-flow in a vertical fracture that is imbedded in impermeable rock and is vertically confined by permeable rock layers. This model was verified by a corresponding 1D-numerical model and was then used to fit the observed pressure records of the constant rate interference test. The fitting procedure yielded a transmissivity of the self-propped fracture in claystone that is more than ten times lower than the transmissivity of self-propped fractures in granite as observed in HDR/EGS systems (Hot-Dry-Rock/Enhanced Geothermal Systems). At the same time it is more than ten times higher than the transmissivity of propped fractures in shale gas reservoirs. The injectivity index of the studied fracture resulting from transmissivity and the high length to height ratio of the fracture enables to circulate water or brine through the fracture at flow rates up to about 0.005 m3/s. For the given temperature of about 150°C this would satisfy the heat demand of small to medium size building complexes. Higher flow rates and heat production could be achieved with multiple fractures of this kind. The results obtained in borehole Horstberg Z1 are promising but more in-situ experiments in various rock formations and different stress regimes are necessary to generalize the results.

The Distribution of Petroleum Resources and Characteristics of Main Petroliferous Basins along the Silk Road Economic Belt and the 21st‐Century Maritime Silk Road

AbstractThe Silk Road Economic Belt and the 21st‐Century Maritime Silk Road Initiative, abbreviated as the Belt and Road Initiative, is a primary development strategy of China's future international cooperation. Especially, the energy resource cooperation, including oil and gas resources cooperation, is an important part of this initiative. The Belt and Road has undergone complicated geological evolution, and contains abundant mineral resources such as oil, gas, coal, uranium, iron, copper, gold and manganese ore resources. Among these, Africa holds 7.8% of the world's total proven oil reserves. The oil and gas resources in Africa are relatively concentrated, with an overall low exploration degree and small consumption demand. Nigeria and Libya contain the most abundant oil resources in Africa, accounting for 2.2% and 2.9% of the world's total reserves, respectively. Nigeria and Algeria hold the richest natural gas resources in Africa, occupying 2.8% and 2.4% of the world's total reserves, respectively. Africa's oil and gas resources are mainly concentrated in Egypt, Sultan and Western Sahara regions in the northern Africa, and the Gulf of Guinea, Niger River and Congo River area in the western Africa. The Russia–Central Asia area holds rich petroleum resources in Russia, Kazakhstan, Turkmenistan and Uzbekistan. The potential oil and gas areas include the West Siberia Basin, East Siberia Basin and sea continental shelf in Russia, the northern and central Caspian Basin in Kazakhstan, the right bank of the Amu‐Darya Basin, the East Karakum uplift and the South Caspian Basin in Turkmenistan, and the Amu–Daria Basin, Fergana Basin, Afghan–Tajik Basin and North Ustyurt Basin in Uzbekistan. The Middle East oil and gas resources are mainly distributed in the Zagros foreland basin and Arabian continental margin basin, and the main oil‐producing countries include Saudi Arabia, Iran and Iraq. The Asia Pacific region is a new oil and gas consumption center, with rapid growth of oil and gas demand. In 2012, this region consumed about 33.6% of the world's total oil consumption and 18.9% of the world's total natural gas consumption, which has been ranked the world's largest oil and gas consumption center. The oil and gas resources are concentrated in China, Indosinian, Malaysia, Australia and India. The abundant European proven crude oil reserves are in Norway, Britain and Denmark and also rich natural gas resources in Norway, Holland and Britain. Norway and Britain contain about 77.5% of European proven oil reserves, which accounts for only 0.9% of the world's proven reserves. The Europe includes main petroliferous basins of the Voring Basin, Anglo–Dutch Basin, Northwest German Basin, Northeast German–Polish Basin and Carpathian Basin. According to the analysis of source rocks, reservoir rocks, cap rocks and traps for the main petroliferous basins, the potential oil and gas prospecting targets in the Belt and Road are mainly the Zagros Basin and Arabic Platform in the Middle East, the East Barents Sea Basin and the East Siberia Basin in Russia–Central Asia, the Niger Delta Basin, East African rift system and the Australia Northwest Shelf. With the development of oil and gas theory and exploration technology, unconventional petroleum resources will play an increasingly important role in oil and gas industry.

A Copernicus downstream-service for the nationwide monitoring of surface displacements in Germany

Advanced interferometric SAR processing techniques (Persistent Scatterer Interferometry, Small Baseline Subset) are able to detect and monitor various surface displacements caused by e.g. gravitative mass movement, subrosion, groundwater extraction, fluid injection, natural gas extraction. These processes can e.g. cause damage to buildings and infrastructure, affect ecosystems and agriculture or affect the economic use of the geological underground by influencing the hydrogeological setting. Despite the maturity and operational readiness of the PSI technology it is rarely used in operational workflows of the German user community (e.g. from responsible authorities).In order to support the operational use of this technique a “Ground Motion Service Germany” has been designed by the Federal Institute for Geosciences and Natural Resources (BGR) in collaboration with the user community, land surveying agencies, SME and research institutions. A major outcome of this collaboration is the user request regarding a PSI-WAP (Persistent Scatterer Interferometry Wide-Area-Product) dataset of the entire nation (approx. 360,000km2) based on Sentinel-1 data. For this reason the PSI mapping coverage is increased by mosaicking PSI data products from adjacent SAR data stacks. Several case studies has been performed to demonstrate the design of the service. Within this paper one case study regarding the PSI-WAP technique and the calibration/validation scheme is presented.The pilot study is focusing on the built up of an officially approved PSI-WAP dataset. The study area covers an area of >30,000km2 and is located in the Northwest German Basin. This is the first time a PSI-WAP analysis is performed in this area. Several natural processes (e.g. compaction of marine sediments, peat growth/shrinkage) and anthropogenic activities (e.g. natural gas extraction, rock salt mining) are causing surface displacements in the study area. The PSI-WAP analysis is based on six adjacent ERS-1/-2 data stacks covering the timespan from 1992 until 2001. Each data stack consists of 49 to 73 acquisitions. A comparison of the PSI results with thematic data (e.g. cumulated volume of extracted natural gas and location of natural gas fields) indicates that a part of the detected land subsidence is caused by natural gas extraction.To summarize, this paper shows i) the design of the “Ground Motion Service Germany” and ii) a pilot study to exemplarily demonstrate a PSI-WAP, the calibration/validation scheme and value-added-products.

A 3D model of the Wathlingen salt dome in the Northwest German Basin from joint modeling of gravity, gravity gradient, and curvature

In the past few decades, numerous attempts have been made on modeling of salt tectonics and deciphering the geometry of salt domes, which is a key challenge in petroleum exploration. We have derived a 3D density model of the Wathlingen salt dome, situated in the southern part of the Northwest German Basin from joint modeling of reprocessed torsion balance measurements. Gravity, gravity gradients [Formula: see text], curvature derived from horizontal gravity gradients [Formula: see text], and horizontal directive tendency are jointly modeled to decipher the geometric structure of the salt dome. The model was constrained by geologic and borehole information. We found that the Wathlingen salt dome is a mushroom-structured salt body, which is 14-km long, 4–8-km wide extending up to [Formula: see text] depth. The top mushroom structure of the salt is horizontally spread up to [Formula: see text]. It would not have been possible to derive the complex 3D structure from modeling of gravity data alone.

Empirical relations of rock properties of outcrop and core samples from the Northwest German Basin for geothermal drilling

<p><strong>Abstract.</strong> Information about geomechanical and physical rock properties, particularly uniaxial compressive strength (UCS), are needed for geomechanical model development and updating with logging-while-drilling methods to minimise costs and risks of the drilling process. The following parameters with importance at different stages of geothermal exploitation and drilling are presented for typical sedimentary and volcanic rocks of the Northwest German Basin (NWGB): physical (<i>P</i> wave velocities, porosity, and bulk and grain density) and geomechanical parameters (UCS, static Young's modulus, destruction work and indirect tensile strength both perpendicular and parallel to bedding) for 35 rock samples from quarries and 14 core samples of sandstones and carbonate rocks. <br><br> With regression analyses (linear- and non-linear) empirical relations are developed to predict UCS values from all other parameters. Analyses focus on sedimentary rocks and were repeated separately for clastic rock samples or carbonate rock samples as well as for outcrop samples or core samples. Empirical relations have high statistical significance for Young's modulus, tensile strength and destruction work; for physical properties, there is a wider scatter of data and prediction of UCS is less precise. For most relations, properties of core samples plot within the scatter of outcrop samples and lie within the 90% prediction bands of developed regression functions. The results indicate the applicability of empirical relations that are based on outcrop data on questions related to drilling operations when the database contains a sufficient number of samples with varying rock properties. The presented equations may help to predict UCS values for sedimentary rocks at depth, and thus develop suitable geomechanical models for the adaptation of the drilling strategy on rock mechanical conditions in the NWGB.</p>

Fracture systems in normal fault zones crosscutting sedimentary rocks, Northwest German Basin

Field studies of fracture systems associated with 58 normal fault zones crosscutting sedimentary rocks were performed in the Northwest German Basin. Fracture orientations, densities, apertures and lengths, as well as fault zone structural indices, were analysed separately for fault damage zones and host rocks. The results show a pronounced difference between carbonate and clastic rocks: mainly in carbonate rocks we found presence of clear damage zones, characterized by higher fracture densities than in the host rocks. While the maximum aperture is similar for both units, the percentage of fractures with large apertures is much higher in the damage zones than in the host rocks.Based on laboratory measurements of Young's moduli and field measurements of fracture densities, we calculate effective stiffnesses Ee, that is the Young's moduli of the in situ rock masses, within the normal fault zones. Compared with carbonate rocks, Ee computed for clastic-rock damage zones decreases significantly less due to lower fracture densities. We conclude that normal fault zones in carbonate rocks have more profound effects on enhancing permeability in fluid reservoirs than those in clastic rocks. The results are of great importance for modelling the hydromechanical behaviour of normal fault zones in subsurface fluid reservoirs.

Intrusion versus inversion—a 3D density model of the southern rim of the Northwest German Basin

An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong, positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model” against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes. We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density, intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed investigations.

Petroleum generation and migration in the ‘Tight Gas’ area of the German Rotliegend natural gas play: a basin modelling study

The Northwest German Basin is an important hydrocarbon province with considerable reserves of natural gas accumulated at its centre. To unravel the thermal and maturation history of the Carboniferous source rocks, particularly gas generation and migration, a combined petrological–geochemical and numerical basin modelling study was performed. Generally two main phases of maturation can be assigned to the Triassic–Late Jurassic and latest Cretaceous–Present intervals. Maturity data reflect the latter event and are consistent with a variable heat flow of 60–63 mW m −2 during Cretaceous–Tertiary burial which accounts for considerable late gas generation. Vitrinite reflectance data and maturity modelling show the Top pre-Permian strata in the northern part of the basin to be in the gas window at present, with a rather uniform maturity of VR r = 1.5% to 2.0% (at 4600–5100 m). However, the important top coal marker is at different depth levels and reveals a more complex coalification pattern, suggesting a strong structural control on maturation of source rocks. This effect is influenced locally by the high thermal conductivity of large salt bodies in the overburden. A significant delay in gas generation from source rocks at elevated horst blocks can be observed. The generation and migration of pre-Westphalian gas started during Late Carboniferous times, when much of the gas was lost from the basin due to ineffective seals. With ongoing burial, gas migration from Westphalian source rocks started in Early Triassic times within Permian graben areas, but was actually delayed until the Late Cretaceous at highly elevated horst blocks. The gas from early migration phases was replaced almost entirely by successively younger Westphalian gas.

Subsurface seismic record of salt glaciers in an extensional intracontinental setting (Late Triassic of northwestern Germany)

Research Article| November 01, 2007 Subsurface seismic record of salt glaciers in an extensional intracontinental setting (Late Triassic of northwestern Germany) Markus Mohr; Markus Mohr 1Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, 52056 Aachen, Germany Search for other works by this author on: GSW Google Scholar John K. Warren; John K. Warren 2Shell Chair in Carbonate Studies, Sultan Qaboos University, Muscat, Oman Search for other works by this author on: GSW Google Scholar Peter A. Kukla; Peter A. Kukla 3Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, 52056 Aachen, Germany Search for other works by this author on: GSW Google Scholar Janos L. Urai; Janos L. Urai 3Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, 52056 Aachen, Germany Search for other works by this author on: GSW Google Scholar Anton Irmen Anton Irmen 4Gaz de France Produktion Exploration Deutschland GmbH, Lingen (Ems), Germany Search for other works by this author on: GSW Google Scholar Author and Article Information Markus Mohr 1Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, 52056 Aachen, Germany John K. Warren 2Shell Chair in Carbonate Studies, Sultan Qaboos University, Muscat, Oman Peter A. Kukla 3Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, 52056 Aachen, Germany Janos L. Urai 3Geological Institute, RWTH Aachen University, Wüllnerstrasse 2, 52056 Aachen, Germany Anton Irmen 4Gaz de France Produktion Exploration Deutschland GmbH, Lingen (Ems), Germany Publisher: Geological Society of America Received: 20 Sep 2006 Revision Received: 08 Jun 2007 Accepted: 14 Jun 2007 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 The Geological Society of America, Inc. Geology (2007) 35 (11): 963–966. https://doi.org/10.1130/G23378A.1 Article history Received: 20 Sep 2006 Revision Received: 08 Jun 2007 Accepted: 14 Jun 2007 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Markus Mohr, John K. Warren, Peter A. Kukla, Janos L. Urai, Anton Irmen; Subsurface seismic record of salt glaciers in an extensional intracontinental setting (Late Triassic of northwestern Germany). Geology 2007;; 35 (11): 963–966. doi: https://doi.org/10.1130/G23378A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract In the Northwest German Basin of Central Europe, Late Triassic interaction of normal faulting and salt diapirism during regional extension in subsalt basement locally initiated lateral flow of surface-piercing salt in namakiers (salt glaciers). Using seismic sections and variance attribute maps derived from high-resolution three-dimensional seismic data, we show that when a syndepositional fault cuts a near-emergent diapir crest, the caprock carapace was breached, opening a pathway for salt extrusion. The fault escarpment and the adjacent fault-induced depression allowed focused gravity-driven downward flow of salt across the land surface (a namakier) and its subsequent preservation and encasement in continental (arid redbed) sediments. Geodynamically there is an apparent distinction between the compressional setting of modern namakiers in the arid deserts of Iran and the fault-intersected extensional setting of stacked Keuper namakiers. Stacked namakiers preserved in thicknesses that are seismically resolvable are interpreted to indicate hyperarid conditions in Keuper time. The climate was typical of the highly continental Late Triassic Pangaean supercontinent as it rifted and sagged to form the incipient Atlantic Ocean. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Velocity-depth trends in Mesozoic and Cenozoic sediments from the Norwegian Shelf: Discussion

Storvoll et al. (2005) present log data from 60 wells on the Norwegian Shelf to investigate velocity-depth trends in sedimentary rocks. They present an interesting analysis of, e.g., the sonic-log velocities of overpressured Jurassic sediments and of source rock intervals. The authors do, however, reach the conclusion that “no general velocity-depth function can be used when performing more accurate analyses like depth conversion of seismic data, pore-pressure prediction, or basin modeling” (Storvoll et al., 2005, p. 359). This conclusion is surprising for two reasons: first, because it is not tested by the authors, and second, because the article presents very good evidence for the existence of normal velocity-depth trends for shale (i.e., functions that describe how sonic velocity increases with depth in relatively homogenous, sedimentary formations as porosity is reduced during normal compaction). The authors present log data from three areas along the Norwegian Shelf (but no examples of pressure versus depth): the northern North Sea, Haltenbanken, and the Barents Sea (about 60°N, 65°N, and 72°N, respectively). The main figures show velocity measurements versus depth for several wells in the three study areas (their figures 6, 8, 12). The authors compare the data with a linear velocity-depth trend: V p = 1477 + 0.57 × Z , which is similar to the normal velocity-depth trend for marine shale dominated by smectite-illite published by Japsen (2000): ![Formula][1] where V p is velocity in meters per second, and Z is depth in meters below seabed or ground level. This trend is almost identical to that developed by Scherbaum (1982) for Lower Jurassic shale in the Northwest German Basin and to that presented by Hansen (1996) based on data for Cretaceous–Cenozoic shales on the Norwegian Shelf (for depths less than about 2.5 km [1.6 mi]). It is interesting that the presented shale … [1]: /embed/graphic-1.gif

Recent Advances in Research on Terrestrial and Marine Sequences From the Mid-Cretaceous Oceanic Anoxic Events (OAEs)

The Cretaceous period was a time of greenhouse climates characterized by sea-surface temperatures of at least 15°C warmer than today. During the climax of Cretaceous warming, anoxic conditions in the oceans expanded globally, resulting in accumulations of organic-rich sediments (socalled black shales). These events, called Oceanic Anoxic Events (OAEs), occurred at least eight times during the Cretaceous period (Fig. 1). Three important aspects make the study of OAEs so interesting: (a) the OAEs acted as a global thermostat because carbon to a large extent was sequestered in the sediments (black shales) instead of adding to the CO2 content of the atmosphere, (b) the expansion of anoxic conditions in the oceans caused mass extinctions of marine biota, and (c) most hydrocarbon source rocks from the Cretaceous formed under anoxic oceanic environments. The discovery of the Cretaceous OAEs (Schlanger and Jenkyns, 1976) was an important achievement of the Deep Sea Drilling Project (DSDP), and understanding Cretaceous OAEs is one of the major scientifi c objectives of the extreme climate initiative outlined in the Integrated Ocean Drilling Program (IODP) Initial Science Plan. To support this initiative a symposium entitled “Recent Advances in Research on Terrestrial and Marine Sequences from the midCretaceous Oceanic Anoxic Events (OAEs)” was held at Hokkaido University, Sapporo, Japan during 21–23 September 2005. The symposium was hosted by the 21 st Century Center of Excellence (COE) Program for the Neo-Science of Natural History, and was organized by Hisatake Okada (COE program leader) and Hiroshi Nishi. Thirteen talks were given, eight by invited speakers, and eight posters dealt with land and marine OAE sections shown in Figure 2. Discussion of land sections concentrated on two types of regions: (a) those with black shale, such as Umbria-Marche Basin, Western Interior, Northwest German Basin and Vocontian Basin; and (b) those devoid of black shale, such as the AngloParis Basin, Yezo Basin and Great Valley Basin. For regions of the fi rst type, the group discussed results of high-resolution studies on a millimeter to centimeter scale of microfossils and organic and inorganic geochemical analyses. It was demonstrated that the black shales in continental interiors and on the continental margins were deposited during marine transgressions, with individual laminae corresponding to the increased runoff from the land areas. For regions of the second type, attention was paid to the integrated analysis of macro- and microfossil and carbon isotope stratigraphies for identifi cation of the precise horizons of OAE levels. Although fully anoxic environments apparently did not develop in these basins, clear evidence of remarkable faunal turnover, involving various taxa, was shown at the OAE levels. Studies of the marine sections dealt with core data mainly from Blake Nose (ODP Leg 171B) and the Demerara Rise (ODP Leg 207). Both sections have yielded extremely well-preserved calcareous fossils suitable for isotopic geochemical analysis. Oxygen and carbon isotope data on planktic and benthic foraminifers revealed the development of two types of water-column structures during

Quantification of recent movement potentials in Schleswig-Holstein (Germany) by GIS-based calculation of correlation coefficients

In order to investigate connections between deep tectonic and halokinetic structures and the development of recent topography, GIS-based calculation of correlation coefficients was carried out between different stratigraphic horizons of the deep Northwest German Basin (NGB) according to the “Geotektonischer Atlas von NW-Deutschland” and surface topography of Schleswig-Holstein. The results show seven areas of high correlation that are traceable from the Base Zechstein up to the recent surface topography. Five areas with high correlation are connected to NNE–SSW trending salt structures within the Gluckstadt Trough, i.e. the area of the salt domes Oldensworth, Tellingstedt, Eisendorf and, to the north of Hamburg, the area of the salt domes Elmshorn and Sievershutten. Two areas, however, with NW–SE trending high correlation are located in the northwest (restricted to the Westschleswig Block) and the northeast (south of Fehmarn) outside the Gluckstadt Trough. These NW–SE trending correlation areas are not related to known salt structures and/or faults but match the general orientation of faults in the NGB.

Too old for Modern Exploration? Old Torsion Balance Observations Revisited

Although gravity gradiometry was among the first geophysical methods used successfully in applied geophysics (Eotvos torsion balance), the technology fell from favour after the 1930s. Here we present a new analysis of torsion balance measurements that were made at this time to detect salt domes in the Northwest German Basin.The study was aimed at assessing methods for interpretation of torsion balance observations. The approach is to synthesize classical procedures with computer based numerical methods, taking horizontal gradients Wxz and Wyz as input parameters. First we give an overview of torsion balance operational details and then discuss the interpretation of torsion balance data.A total of 39 maps at 1:25,000 scale covering the Northwest German Basin have been digitised. These maps provide some 40,000 torsion balance measurements, but no field books or field forms are available. The gradients were digitised from old paper maps, then reprocessed and recalculated. 3D modelling of Wxz, Wyz and other components of the Eotvos tensor provides detailed insight into the geometry of salt domes and provides additional constraints for modelling the Bouguer gravity field.3D forward modelling is conducted using the IGMAS program package. This package allows the calculation of potential, gravity and its components, and the Eotvos tensor components. Results show that knowledge of the second derivatives of the potential could fundamentally change the role of gravity field measurements in underground investigations, not only for resource exploration, but also for investigations of large fault systems like the Dead Sea Transform.

Stress orientations found in north‐east Germany differ from the West European trend

Knowledge about the acting stresses is of crucial importance for understanding the tectonics of a region. Data about the stress field in north‐eastern Germany used to be very rare. In general, it was assumed that the orientation of the larger horizontal principal stress (SH) is similar to that found for western Germany and central West‐Europe, i.e. NW–SE. To check this, several borehole logs of the late 1980s were analysed for information on the principal horizontal stress orientations: they include Four‐Arm‐Dipmeter and borehole televiewer data from 15 boreholes. The depth range of our stress results reaches from 1500 to 6700 m. They were compared to a few other data, especially from hydraulic fracturing, and to recent findings on the stresses in the Northwest German basin. In contrast to expectation, SH derived from breakout orientations below the salt layers displayed N to NE orientation. The latter was found at 10 locations spread over the NE‐German basin from Berlin to the Baltic sea, from the Polish border to the former border between East and West Germany. Moreover, this stress rotation in the subsaline formations seems to be the continuation of a trend found in the NW German basin.

Abstract: 2-D Basin Modeling in the North West German Basin – Influence of Reservoir Model on Gas Distribution

Abstract: 2-D Basin Modeling in the North West German Basin – Influence of Reservoir Model on Gas Distribution

Integration of data constraints and potential field modelling — an example from southern lower saxony, Germany

Most of interpretational tasks in geophysics require an interdisciplinary knowledge and integration of information from comprehensive data bases. Towards this end a combination of different geophysical surveys employing seismics, gravity and magnetics, provides new insights into the structures and tectonic evolution of natural deposits together with geological and petrological studies. No doubt, any interdisciplinary approach is essential for numerical modelling of these structures and the processes acting on it. The interpretation of garvity and magnetics by 3D modelling requires data from other independent sources, due to the ambiguity of these methods.In close cooperation with geologists and computer scientists we are developing an object oriented model of the southern rim of the Northwest German Basin which consists of information from industry wells, stratigraphy and geophysical parameters (e.g. density and susceptibility). GOCAD is used for geometrical modelling purposes, IGMAS handels the interactive modifications of geophysical model parameters and geometry. Both modelling programs are supported by an object oriented data base system which will guarantee the consistency of data and models.Combined interpretations of the southern basin are presented and show, how the information from different geo-disciplines is visualized in order to ease the modelling process.

Stellungnahme zum Aufsatz von Neunzert, G. H. Gaupp, R. & Littke, R.: Absenkungs- und Temperaturgeschichte paläozoischer und mesozoischer Formationen im Nordwestdeutschen Becken (Z. dt. geol. Ges., 147: 183-208)

Stellungnahme zum Aufsatz von Neunzert, G. H. Gaupp, R. & Littke, R.: Absenkungs- und Temperaturgeschichte paläozoischer und mesozoischer Formationen im Nordwestdeutschen Becken (Z. dt. geol. Ges., 147: 183-208)

Absenkungs- und Temperaturgeschichte paläozoischer und mesozoischer Formationen im Nordwestdeutschen Becken: Stellungnahme zum Diskussionsbeitrag von W. Jaritz

Absenkungs- und Temperaturgeschichte paläozoischer und mesozoischer Formationen im Nordwestdeutschen Becken: Stellungnahme zum Diskussionsbeitrag von W. Jaritz