scholarly journals The Crustal Stress Field of Germany - A Refined Prediction

2021 ◽  
Author(s):  
Steffen Ahlers ◽  
Luisa Röckel ◽  
Tobias Hergert ◽  
Karsten Reiter ◽  
Oliver Heidbach ◽  
...  
Keyword(s):  
Stress Field ◽  
Sedimentary Basins ◽  
Horizontal Stress ◽  
Rock Properties ◽  
Upper Rhine Graben ◽  
Calibration Data ◽  
Directional Drilling ◽  
In Situ Data ◽  
The North ◽  
The Absolute

Abstract Information about the absolute stress state in the upper crust plays a crucial role in the planning and execution of e.g., directional drilling, stimulation and exploitation of geothermal and hydrocarbon reservoirs. Since many of these applications are related to sediments, we present a refined geomechanical-numerical model for Germany with focus on sedimentary basins, able to predict the complete 3D stress tensor. The lateral resolution of the model is 2.5 km, the vertical resolution about 250 m. Our model contains 22 units with focus on the sedimentary layers parameterized with individual rock properties. The model results show an overall good fit with magnitude data of the minimum (Shmin) and maximum horizontal stress (SHmax) that are used for the model calibration. The mean of the absolute stress differences between these calibration data and the model results is 4.6 MPa for Shmin and 6.4 MPa for SHmax. In addition, our predicted stress field shows good agreement to several supplementary in situ data from the North German Basin, the Upper Rhine Graben and the Molasse Basin.

Fractures in the northern plains, stream patterns, and the midcontinent stress field

1987 ◽  
Vol 24 (6) ◽  
pp. 1086-1097 ◽  
Author(s):  
Mel R. Stauffer ◽  
Don J. Gendzwill
Keyword(s):  
Stress Field ◽  
Horizontal Stress ◽  
The Body ◽  
North American Plate ◽  
Plate Motion ◽  
Viscous Drag ◽  
Near Surface ◽  
The North ◽  
Elastic Rebound ◽  
Western North Dakota

Fractures in Late Cretaceous to Late Pleistocene sediments in Saskatchewan, eastern Montana, and western North Dakota form two vertical, orthogonal sets trending northeast–southwest and northwest–southeast. The pattern is consistent, regardless of rock type or age (except for concretionary sandstone). Both sets appear to be extensional in origin and are similar in character to joints in Alberta. Modem stream valleys also trend in the same two dominant directions and may be controlled by the underlying fractures.Elevation variations on the sub-Mannville (Early Cretaceous) unconformity form a rectilinear pattern also parallel to the fracture sets, suggesting that fracturing was initiated at least as early as Late Jurassic. It may have begun earlier, but there are insufficient data at present to extend the time of initiation.We interpret the fractures as the result of vertical uplift together with plate motion: the westward drift of North America. The northeast–southwest-directed maximum principal horizontal stress of the midcontinent stress field is generated by viscous drag effects between the North American plate and the mantle. Vertical uplift, erosion, or both together produce a horizontal tensile state in near-surface materials, and with the addition of a directed horizontal stress through plate motion, vertical tension cracks are generated parallel to that horizontal stress (northeast–southwest). Nearly instantaneous elastic rebound results in the production of second-order joints (northwest–southeast) perpendicular to the first. In this manner, the body of rock is being subjected with time to complex alternation of northeast–southwest and northwest–southeast horizontal stresses, resulting in the continuous and contemporaneous production of two perpendicular extensional joint sets.

Geodynamic implications of the Cenozoic stress field on Seymour Island, West Antarctica

2008 ◽  
Vol 20 (2) ◽  
pp. 173-184 ◽  
Author(s):  
A. Maestro ◽  
J. López-Martínez ◽  
F. Bohoyo ◽  
M. Montes ◽  
F. Nozal ◽  
...  
Keyword(s):  
Stress Field ◽  
Antarctic Peninsula ◽  
Horizontal Stress ◽  
Weddell Sea ◽  
Scotia Sea ◽  
Compressional Stress ◽  
The North ◽  
Stress States ◽  
Bransfield Basin ◽  
Minimum Horizontal Stress

AbstractPalaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ3) orientations are scattered about two main NE–SW and NW–SE modes suggesting that two stress sources have been responsible for the dominant minimum horizontal stress directions in the north-western Weddell Sea. Extensional structures within a broad-scale compressional stress field can be linked to both the decrease in relative stress magnitudes from active margins to intraplate regions and the rifting processes that occurred in the northern Weddell Sea. Stress states with NW–SE trending σ3are compatible with back-arc extension along the eastern Antarctic Peninsula. We interpret this as due to the opening of the Larsen Basin during upper Cretaceous to Eocene and to the spreading, from Pliocene to present, of the Bransfield Basin (western Antarctic Peninsula), both due to former Phoenix Plate subduction under the Antarctic Plate. NE–SW σ3orientations could be expressions of continental fragmentation of the northern Antarctic Peninsula controlling eastwards drifting of the South Orkney microcontinent and other submerged continental blocks of the southern Scotia Sea.

Thermal signature of the lithosphere below sedimentary basins in extensional, compressive and transform settings

2020 ◽  
Author(s):  
Magdalena Scheck-Wenderoth ◽  
Judith Bott ◽  
Mauro Cacace ◽  
Denis Anikiev ◽  
Maria Laura Gomez Dacal ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Internal Heat ◽  
Sedimentary Basins ◽  
Rift System ◽  
Upper Rhine Graben ◽  
East African Rift System ◽  
Forming Mechanism ◽  
Passive Margins ◽  
The North ◽  
Thermal Signature

<p>The configuration of the lithosphere below sedimentary basins varies in response to the basin-forming mechanism, the lifetime of the causative stress fields and the lithological heterogeneity inherited from pre-basin tectonic events. Accordingly, the deep thermal configuration is a function of the tectonic setting, the time since the thermal disturbance occurred and the internal heat sources within the lithosphere. We compare deep thermal configurations in different settings based on data-constrained 3D lithosphere-scale thermal models that consider both geological and geophysical observations and physical processes of heat transfer. The results presented come from a varied range of tectonic settings including: (1) the extensional settings of the Upper Rhine Graben and the East African Rift System, where we show that rifts can be hot for different reasons; (2) the North and South Atlantic passive margins, demonstrating that magma-rich passive margins can be comparatively hot or cold depending on the thermo-tectonic age; (3) the Alps, where we find that foreland basins are influenced by the conductive properties and heat-producing units of the adjacent orogen; and (4)the Sea of Marmara, along the westernmost sector of the North Anatolian Fault Zone, that suggest strike-slip basins may be thermally segmented.</p>

THE STRESS FIELD OF THE NORTH WEST SHELF AND WELLBORE STABILITY

1993 ◽  
Vol 33 (1) ◽  
pp. 373 ◽  
Author(s):  
R.R. Millis ◽  
A.F. Williams
Keyword(s):  
Stress Field ◽  
Horizontal Stress ◽  
Strike Slip ◽  
Wellbore Stability ◽  
Upper And Lower Bounds ◽  
Theoretical Modelling ◽  
Elliptical Cross ◽  
North West ◽  
The North ◽  
Timor Sea

Boreholes drilled in the search for hydrocarbons in the Barrow-Dampier Sub-Basin (North West Shelf, Australia) commonly exhibit an elliptical cross-section believed to be due to stress-induced wellbore failure known as borehole breakout. The azimuths of the long axes of 138 discrete breakouts identified in nine different wells in the Barrow-Dampier show a consistent 010°−030°N trend implying that maximum horizontal compressive stress is oriented 100°−12G°N.The orientation of horizontal stress determined in this study (and that from the Timor Sea area which is rotated some 50°−60° with respect to the Barrow-Dampier) is consistent with that derived from theoretical modelling of the stress within the Indo-Australian plate based on the plate tectonic forces acting on its boundaries. The rotation of the horizontal stress orientations along the North West Shelf, between the Barrow-Dampier and the Timor Sea, is a reflection of the present-day complex plate convergence system at the north-eastern boundary of the Indo-Australian Plate.Vertical stress magnitudes, Sv, in the Barrow-Dampier were determined from density and sonic log data. Minimum and maximum horizontal stress magnitudes, Shmin and Shmax, were determined from mini-hydraulic fracture (or modified leak-off) test results. These data suggest that the fault condition of the Wanaea/Cossack area is on the boundary between normal faulting (extension) and strike-slip, i.e. Sv ≈ Shmax > Shmin. However, in other parts of the Barrow-Dampier the evidence suggests a strike-slip fault condition, i.e. Shmax > Sv > Shmin.Given the orientation of the stress field and the fault condition, inferences can be drawn regarding the stability of horizontal wells. Furthermore, experience from vertical wells can be utilized to determine the upper and lower bounds to the mud-weight envelope as functions of deviation and wellbore orientation. Since a horizontal well will see Sv and a horizontal stress, stress anisotropy around a wellbore in the Wanaea/Cossack area (and hence wellbore instability) will be minimized by drilling in the Shmin direction i.e. 010°–030°N.

Clay mineral diagenesis in sedimentary basins — a key to the prediction of rock properties. Examples from the North Sea Basin

Clay Minerals ◽  
1998 ◽  
Vol 33 (1) ◽  
pp. 15-34 ◽  
Author(s):  
K. Bjørlykke
Keyword(s):  
Clay Mineral ◽  
North Sea ◽  
Meteoric Water ◽  
Sedimentary Basins ◽  
Rock Properties ◽  
The North ◽  
Through Flow ◽  
The North Sea ◽  
Low Solubility

AbstractDissolution of feldspar and mica and precipitation of kaolinite require a through flow of meteoric water to remove cations such as Na+ and K+ and silica. Compaction driven pore-water flow is in most cases too slow to be significant in terms of transport of solids. The very low solubility of A1 suggests that precipitation of new authigenic clay minerals requires unstable Al-bearing precursor minerals. Chlorite may form diagenetically from smectite and from kaolinite when a source of Fe and Mg is present. In the North Sea Basin, the main phase of illite precipitation reducing the quality of Jurassic reservoirs occurs at depths close to 4 km (130-140°C) but the amount of illite depends on the presence of both kaolinite and K-feldspar. Clay mineral reactions in shales and sandstones are very important factors determining mechanical and chemical compaction and are thus critical for realistic basin modelling.

scholarly journals A comprehensive model of seismic velocities for the Bay of Mecklenburg (Baltic Sea) at the North German Basin margin: implications for basin development

2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Michael Schnabel ◽  
Vera Noack ◽  
Niklas Ahlrichs ◽  
Christian Hübscher
Keyword(s):  
Model Building ◽  
Sedimentary Basins ◽  
Lower Triassic ◽  
Upper Jurassic ◽  
Rock Properties ◽  
Seismic Velocities ◽  
North German Basin ◽  
Seismic Profiles ◽  
The North ◽  
German Basin

AbstractThe geometry of sedimentary basins is normally described by the interpretation of seismic reflectors. In addition to that, rock properties of the sedimentary successions between these reflectors give further insight into the subsurface geology. Here, we present a model for the Bay of Mecklenburg, situated at the northeastern margin of the North German Basin. The model consists of eight layers; it covers seismic velocities of sediments from the Neogene down to the base of the Permian Zechstein. We use eight seismic profiles for model building and apply seismic migration velocity analysis in combination with pre-stack depth migration. The results are interval velocities down to a depth of 5000 m. A further aim of the study is to investigate the sensitivity of these indirectly deduced velocities in comparison to direct measurements within drill holes. The velocities from this study are in good agreement with earlier results from vertical seismic profiling at a nearby well. Cenozoic and Mesozoic strata within the Bay of Mecklenburg show clear depth-dependent velocity trends. A comparison of these trends with predicted compaction trends shows that burial anomalies within Lower Triassic units are significantly higher than in Upper Cretaceous units. This finding could be explained by a greater amount of erosion during Upper Jurassic/Lower Cretaceous times than during Cenozoic times. The Zechstein layer shows a decreasing interval velocity with increasing thickness. Our study demonstrates that seismic velocities deduced from surface-based measurements are of high value in areas with sparse drilling coverage.

Rola Avarského Kaganátu Pri Vzniku Slovenčiny

2018 ◽  
Vol 69 (2) ◽  
pp. 199-236
Author(s):  
Martin Braxatoris ◽  
Michal Ondrejčík
Keyword(s):  
Slavic Language ◽  
The West ◽  
The North ◽  
Danube Region ◽  
The Absolute ◽  
North Edge ◽  
The Relationship ◽  
Slovak Language

Abstract The paper proposes a basis of theory with the aim of clarifying the casual nature of the relationship between the West Slavic and non-West Slavic Proto-Slavic base of the Slovak language. The paper links the absolute chronology of the Proto-Slavic language changes to historical and archaeological information about Slavs and Avars. The theory connects the ancient West Slavic core of the Proto-Slavic base of the Slovak language with Sclaveni, and non-West Slavic core with Antes, which are connected to the later population in the middle Danube region. It presumes emergence and further expansion of the Slavic koiné, originally based on the non-West Slavic dialects, with subsequent influence on language of the western Slavic tribes settled in the north edge of the Avar Khaganate. The paper also contains a periodization of particular language changes related to the situation in the Khaganate of that time.

Hydrothermal activity in the Upper Permian Ravnefjeld Formation of central East Greenland – a study of sulphide morphotypes

1998 ◽  
pp. 81-87
Author(s):  
Jesper Kresten Nielsen ◽  
Mikael Pedersen
Keyword(s):  
Base Metal ◽  
Early Period ◽  
Sedimentary Basins ◽  
Hydrothermal Activity ◽  
Source Rocks ◽  
Upper Permian ◽  
Thermal Activity ◽  
East Greenland ◽  
The North ◽  
Alum Shale

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kresten Nielsen, J., & Pedersen, M. (1998). Hydrothermal activity in the Upper Permian Ravnefjeld Formation of central East Greenland – a study of sulphide morphotypes. Geology of Greenland Survey Bulletin, 180, 81-87. https://doi.org/10.34194/ggub.v180.5090 _______________ Bituminous shales of the Ravnefjeld Formation were deposited in the subsiding East Greenland basin during the Upper Permian. The shales are exposed from Jameson Land in the south (71°N; Fig. 1) to Clavering Ø in the north (74°20′N) and have attracted considerable attention due to their high potential as hydrocarbon source rocks (Piasecki & Stemmerik 1991; Scholle et al. 1991; Christiansen et al. 1992, 1993a, b). Furthermore, enrichment of lead, zinc and copper has been known in the Ravnefjeld Formation on Wegener Halvø since 1968 (Lehnert-Thiel 1968; Fig. 1). This mineralisation was assumed to be of primary or early diagenetic origin due to similarities with the central European Kupferschiefer (Harpøth et al. 1986). Later studies, however, suggested base metal mineralisation in the immediately underlying carbonate reefs to be Tertiary in age (Stemmerik 1991). Due to geographical coincidence between the two types of mineralisation, a common history is a likely assumption, but a timing paradox exists. A part of the TUPOLAR project on the ‘Resources of the sedimentary basins of North and East Greenland’ has been dedicated to re-investigation of the mineralisation in the Ravnefjeld Formation in order to determine the genesis of the mineralisation and whether or not primary or early diagenetic base metal enrichment has taken place on Wegener Halvø, possibly in relation to an early period of hydrothermal activity. One approach to this is to study the various sulphides in the Ravnefjeld Formation; this is carried out in close co-operation with a current Ph.D. project at the University of Copenhagen, Denmark. Diagenetically formed pyrite is a common constituent of marine shales and the study of pyrite morphotypes has previously been successful from thermalli immature parts of elucidating depositional environment and thermal effects in the Alum Shale Formation of Scandinavia (Nielsen 1996; Nielsen et al. 1998). The present paper describes the preliminary results of a similar study on pyrite from thermally immature parts of the Ravnefjeld Formation which, combined with the study of textures of base metal sulphides in the Wegener Halvø area (Fig. 1), may provide an important step in the evaluation of the presence or absence of early thermal activity on (or below) the Upper Permian sea floor.

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