“…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.…”
The Franconian Platform of SE Germany and the underlying Permian and Triassic rocks that developed from latest Permian to Triassic time were affected by multiple compressional and extensional events that created a complex fracture, fault and stylolite network. We reconstructed the spatio-temporal variations of post-Triassic palaeostress fields in the Franconian Platform and Triassic strata using fault-slip and tectonic stylolite inversion. Our highly resolved stress inversion enables us to demonstrate a cyclic stress evolution from the stress regime of normal faulting to thrusting, strike-slip and back to normal faulting. Five main stress fields correlating with two stress cycles are determined for Late Jurassic to Cenozoic time. The first cycle consists of: (SF1) an initially NE–SW-directed horizontal extension during Late Jurassic to Early Cretaceous time; (SF2) NNE–SSW-directed horizontal compression with an early set of tectonic stylolites prior to the development of reverse and thrust faults; and (SF3) a strike-slip-dominated setting with (N)NE–(S)SW horizontal compression representing a first relaxation. The second cycle comprises (SF4) NW–SE-directed horizontal extension during Oligocene–Miocene time; and (SF5) a second strike-slip-dominated regime with WNW–ESE to NW–SE horizontal compression during the Alpine shortening, creating the youngest set of tectonic stylolites. In addition, we consider the transitional stages between thrusting and a strike-slip regime as a snapshot in the process of intraplate tectonics.
“…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.…”
The Franconian Platform of SE Germany and the underlying Permian and Triassic rocks that developed from latest Permian to Triassic time were affected by multiple compressional and extensional events that created a complex fracture, fault and stylolite network. We reconstructed the spatio-temporal variations of post-Triassic palaeostress fields in the Franconian Platform and Triassic strata using fault-slip and tectonic stylolite inversion. Our highly resolved stress inversion enables us to demonstrate a cyclic stress evolution from the stress regime of normal faulting to thrusting, strike-slip and back to normal faulting. Five main stress fields correlating with two stress cycles are determined for Late Jurassic to Cenozoic time. The first cycle consists of: (SF1) an initially NE–SW-directed horizontal extension during Late Jurassic to Early Cretaceous time; (SF2) NNE–SSW-directed horizontal compression with an early set of tectonic stylolites prior to the development of reverse and thrust faults; and (SF3) a strike-slip-dominated setting with (N)NE–(S)SW horizontal compression representing a first relaxation. The second cycle comprises (SF4) NW–SE-directed horizontal extension during Oligocene–Miocene time; and (SF5) a second strike-slip-dominated regime with WNW–ESE to NW–SE horizontal compression during the Alpine shortening, creating the youngest set of tectonic stylolites. In addition, we consider the transitional stages between thrusting and a strike-slip regime as a snapshot in the process of intraplate tectonics.
“…Similar fault zones south of the Franconian Line are the southernmost expression of Late Cretaceous inversion on the transect in Fig. 4 ( Kämmlein et al, 2020). The Odenwald and Spessart in the west are uplifts of the Variscan basement not associated with major Cretaceous thrust faults (Fig.…”
Section: Study Area In Central Germany and Sample Coveragementioning
Abstract. Large parts of central Europe experienced exhumation
in Late Cretaceous to Paleogene time. Previous studies mainly focused on
thrusted basement uplifts to unravel the magnitude, processes and timing of
exhumation. This study provides, for the first time, a comprehensive
thermochronological dataset from mostly Permo-Triassic strata exposed
adjacent to and between the basement uplifts in central Germany, comprising
an area of at least some 250–300 km across. Results of apatite fission-track
and (U–Th) / He analyses on > 100 new samples reveal that (i) kilometre-scale exhumation affected the entire region, (ii) thrusting of basement
blocks like the Harz Mountains and the Thuringian Forest focused in the Late
Cretaceous (about 90–70 Ma), while superimposed domal uplift of central
Germany is slightly younger (about 75–55 Ma), and (iii) large parts of the
domal uplift experienced removal of 3 to 4 km of Mesozoic strata. Using
spatial extent, magnitude and timing as constraints suggests that thrusting
and crustal thickening alone can account for no more than half of the domal
uplift. Most likely, dynamic topography caused by upwelling asthenosphere
significantly contributed to the observed pattern of exhumation in
central Germany.
“…Subsidence and crustal extension related to the culmination of the Varsican Orogeny formed half-graben and graben structures allowing for deposition to occur from the Late Palaeozoic onwards (Freudenberger & Schwerd, 1996; Bauer, 2000; Schäfer et al 2000; Kroner et al 2007). The Franconian Basin deposition spans from Permian (Rotliegend) to Cretaceous and is formed of sandstones, siltstones, mudstones and limestones (Schröder, 1987; Schäfer et al 2000, Freudenberger et al 2013; Kämmlein et al 2017). The outcrops of interest lie within the Malm (Upper Jurassic) limestone unit deposited as an extensive carbonate-dominated platform (Franconian Platform) along the passive Tethyian margin (Meyer & Schmidt-Kaler, 1990; Ziegler 1990; Schintgen & Moeck, 2021).…”
Section: Geological Setting Of the Franconian Basinmentioning
confidence: 99%
“… Fig. 1. Tectonic overview of central Germany and the Franconian Basin showing the main fault lines and basins within the region (modified from Peterek et al 1996; Kämmlein et al 2017). …”
Section: Geological Setting Of the Franconian Basinmentioning
Faulted and fractured systems form a critical component of fluid flow, especially within low-permeable reservoirs. Therefore, developing suitable methodologies for acquiring structural data and simulating flow through fractured media is vital to improve efficiency and reduce uncertainties in modelling the subsurface. Outcrop analogues provide excellent areas for the analysis and characterization of fractures within the reservoir rocks where subsurface data are limited. Variation in fracture arrangement, distribution and connectivity can be obtained from 2D fractured cliff sections and pavements. These sections can then be used for efficient discretization and homogenization techniques to obtain reliable predictions on permeability distributions in the geothermal reservoirs. Fracture network anisotropy in the Malm reservoir unit is assessed using detailed structural analysis and numerical homogenization of outcrop analogues from an open pit quarry within the Franconian Basin, Germany. Several events are recorded in the fracture networks from the Late Jurassic the Alpine Orogeny and are observed to be influenced by the Kulmbach Fault nearby with a reverse throw of 800 m. The fractured outcrops are digitized for fluid flow simulations and homogenization to determine the permeability tensors of the networks. The tensors show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and therefore faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.
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