Variscan structures and their control on latest to post-Variscan basin architecture: insights from the westernmost Bohemian Massif and southeastern Germany

Abstract

Abstract. The Bohemian Massif exposes structures and metamorphic rocks remnant from the Variscan orogeny in central Europe and is bordered by the Franconian Fault System (FFS) to the west. Across the FFS, Variscan units and structures are buried by Permo-Mesozoic sedimentary rocks. We integrate existing DEKORP 2D seismic reflection, well, and surface geological data with the newly acquired FRANKEN 2D seismic survey to investigate the possible westward continuation of Variscan tectonostratigraphic units and structures and their influence on latest to post-Variscan basin development. Subsurface Permo-Mesozoic stratigraphy is obtained from available wells and tied to seismic reflection profiles using a synthetic seismogram calculated from density and velocity logs. Below the sedimentary cover, three main basement units are identified using seismic facies descriptions that are compared with seismic reflection characteristics of exposed Variscan units east of the FFS. Our results show upper Paleozoic low-grade metasedimentary rocks and possible Variscan nappes bounded and transported by Variscan shear zones ca. 65 km west of the FFS. Basement seismic facies in the footwall of the Variscan shear zones are interpreted as Cadomian basement and overlaying Paleozoic sequences. We show that the location of normal fault-bounded latest to post-Variscan late Carboniferous–Permian basins are controlled by the geometry of underlying Variscan shear zones. Some of these late Carboniferous–Permian normal faults reactivated as steep reverse faults during the regional Upper Cretaceous inversion. Our results also highlight that reverse reactivation of normal faults gradually decreases west of the FFS.

Reconstruction of cyclic Mesozoic–Cenozoic stress development in SE Germany using fault-slip and stylolite inversion

“…Triassic deposits in the study area are fairly tabular with local lateral thickness changes and limited faulting, indicating continuous regional tectonic quiescence (Fig. 1d; Fazlikhani et al 2022).…”

“…1c) and consists of Mesozoic and Cenozoic sedimentary rocks (Freudenberger & Schwerd, 1996). The rocks of the Variscides (Kossmat, 1927) exposed in the Bohemian Massif are buried in the west beneath the Kraichgau Basin fill and the sediments of the Franconian Platform (Paul & Schröder, 2012;Sittig, 2012;Kämmlein et al 2020;Fazlikhani et al 2022). The structural framework at the eastern basin margin is dominated by a NW-SE-striking fault network, the most prominent elements of which are the Franconian and the Eisfeld-Kulmbach fault zones.…”

Petrophysical characterization, BIB-SEM imaging, and permeability models of tight carbonates from the Upper Jurassic (Malm ß), SE Germany

“…After a phase of tectonic quiescence, N-S to NW-SE oriented far-field compressive stresses within the Central European lithosphere related to the Alpine Orogeny (e.g., Scheck-Wenderoth et al 2008;Ziegler 1987;Ziegler et al 1995) and/or the onset of Africa-Iberia-Europe convergence (Kley and Voigt 2008) caused the Late-Cretaceous inversion and the formation of N-S to NNW-SSE trending strike-slip faults accompanied by stylolites with orientations vertical to bedding, bedding parallel, and sub-parallel to the strike of normal faults (Koehler et al 2022) as well as the reversed reactivation of NW-SE striking normal faults (Zulauf 1993). Ultimately, Late-Cretaceous inversion not only led to a cessation of Cretaceous sedimentation but also to the erosion of several hundreds of meters of Mesozoic sediments and widespread reverse reactivation of normal faults (Bachmann et al 1987;von Eynatten et al 2021;Fazlikhani et al 2022;Scheck-Wenderoth et al 2008;Voigt et al 2008Voigt et al , 2021. A second major uplift phase between latest Late Cretaceous and Palaeocene was caused by the combined effects of the Alpine continental collision (Peterek et al 1997;Reicherter et al 2008;Schröder 1987;Wagner et al 1997;Ziegler 1987) and mantle-induced domal uplift in the area of the Upper Rhine Graben Rift (URG) to the west of the study area (von Eynatten et al 2021) (Fig.…”

Comparative petrophysical characterization, BIB-SEM imaging and permeability models of tight carbonates: Case study Upper Jurassic (Malm ß), N Bavaria

“…Scheck-Wenderoth et al, 2008, Ziegler, 1987Ziegler et al, 1995) or the onset of Africa-Iberia-Europe convergence (Kley and Voigt, 2008) caused the Late Cretaceous inversion. Ultimately, the Late Cretaceous inversion not only led to the cessation of Cretaceous sedimentation but also to the erosion of several hundreds of meters of Mesozoic sediments and the reverse reactivation of faults (Bachmann et al, 1987;von Eynatten et al, 2021;Fazlikhani et al, 2022;Scheck-Wenderoth et al, 2008;Voigt et al, , 2021. A second major uplift phase followed between the latest Late Cretaceous and Palaeocene caused by the Alpine continental collision (Peterek et al, 1997;Reicherter et al, 2008;Schröder, 1987;Wagner et al, 1997;Ziegler, 1987) and by mantle-induced domal uplift below the Upper Rhine Graben Rift to the west of the study area (von Eynatten et al, 2021).…”