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The middle to late Permian Hunter Bowen Event is credited with the development of orogenic curvature in the southern New England Orogen, yet contention surrounds the structural dynamics responsible for the development of this curvature. Debate is largely centred on the roles of orogen parallel strike-slip and orogen normal extension and contraction to explain the development of curvature. To evaluate the dynamic history of the Hunter Bowen Event, we present new kinematic reconstructions of the Tamworth Belt. The Tamworth Belt formed as a Carboniferous forearc basin and was subsequently inverted during the Hunter Bowen Event. Kinematic reconstructions of the Tamworth Belt are based on new maps and cross-sections built from a synthesis of best-available mapping, chronostratigraphic data and new interpretations of depth-converted seismic data. The following conclusions are made from our study: (i) the Hunter Bowen Event was dominantly driven by margin normal contraction (east–west shortening; present-day coordinates), and; (ii) variations in structural style along the strike of the Tamworth Belt can be explained by orthogonal vs. oblique inversion, which reflects the angular relationship between the principal shortening vector and continental-arc margin. Given these conclusions, we suggest that curvature around the controversial Manning Bend was influenced by the presence of primary curvature in the continental margin, and that the Hastings Block was translated along a sinistral strike-slip fault system that formed along this oblique (with respect to the regional east–west extension and convergence direction) part of the margin. Given the available temporal data, the translation of the Hastings Block took place in the Early Permian (Asselian) and therefore preceded the Hunter Bowen Event. Accordingly, we suggest that the Hunter Bowen Event was dominantly associated with enhancing curvature that was either primary in origin, or associated with fault block translation during the Early Permian. This model differs to previously proposed reconstructions where curvature largely formed by orogen parallel strike-slip transportation during the Hunter Bowen Event. 相似文献
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The Permo-Carboniferous Saar-Nahe Basin in south-west Germany and north-east France formed at the boundary between the Rhenohercynian and Saxothuringian zones within the Variscan orogen, where non-marine sediments were deposited in a narrow, structurally controlled basin. The basin has an asymmetrical geometry perpendicular to the South Hunsruck Fault. However, there is a lack of growth of the sediment pile into the fault, and isopach maps show the depocentre always located adjacent to the South Hunsrück Fault, but migrating towards the north-east with time. This pattern is typical of a strike-slip basin, indicating that the South Hunsruck Fault was a dextral strike-slip fault during sedimentation. Tectonic subsidence curves indicate that, during the Middle Devonian to Early Carboniferous, the basin subsided due to thermal relaxation of the lithosphere. A change to very rapid subsidence at the start of the Westphalian continued until late in the Autunian. This was due to mechanical subsidence associated with strike-slip movement on the South Hunsruck Fault. Towards the end of subsidence in the Saar-Nahe Basin, the Grenzlager volcanics introduced a thermal pulse into the crust, leading to thermal cooling and relaxation of the lithosphere. 相似文献
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R. Vuthaluru R. A. Vincent D. A. Holdsworth I. M. Reid 《Journal of Atmospheric and Solar》2002,64(18)
Partial reflection differential absorption and differential phase observations have been used to systematically study collision frequencies (ν) in D-region of the lower ionosphere. The observations made with the large MF radar located at Buckland Park (35°S, 138°E) near Adelaide in the period September 1996–December 2000 show ν values larger than predicted by previously used models. The new estimates are compared with values calculated using new collision frequency momentum cross-sections for N2(σ) measured in the laboratory. The two types of measurements are found to be in good agreement, with a moderate seasonal variation of ν at a constant height. No change due to solar cycle variations is found. 相似文献
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Pierre Anquez Jeanne Pellerin Modeste Irakarama Paul Cupillard Bruno Lévy Guillaume Caumon 《Comptes Rendus Geoscience》2019,351(1):48-58
Incorporating prior geological knowledge in geophysical process models often meets practical meshing challenges and raises the question of how much detail is to be included in the geometric model. We introduce a strategy to automatically repair and simplify geological maps, geological cross-sections and the associated meshes while preserving elementary consistency rules. To identify features breaking validity and/or the thin features potentially problematic when generating a mesh, we associate an exclusion zone with each model feature (horizon, fault). When these zones overlap, both the connectivity and the geometry of the geological layers are automatically modified. The output model enforces specific practical quality criteria on the model topology and geometry that facilitates the generation of a mesh with lower bounds on minimum angles and minimum local entity sizes. Our strategy is demonstrated on an invalid geological cross-section from a real-case study in the Lorraine coal basin. We further explore the impacts of the model modifications on wave propagation simulation. We show that the differences on the seismograms due to model simplifications are relatively small if the magnitude of simplifications is adapted to the physical problem parameters. 相似文献
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