Paleostress reconstruction of faults recorded in the Niedźwiedzia Cave (Sudetes): insights into Alpine intraplate tectonic of NE Bohemian Massif

Abstract

Brittle structures identified within the largest karstic cave of the Sudetes (the Niedźwiedzia Cave) were studied to reconstruct the paleostress driving post-Variscan tectonic activity in the NE Bohemian Massif. Individual fault population datasets, including local strike and dip of fault planes, striations, and Riedel shear, enabled us to discuss the orientation of the principal stresses tensor. The (meso) fault-slip data analysis performed both with Dihedra and an inverse method revealed two possible main opposing compressional regimes: (1) NE–SW compression with the formation of strike-slip (transpressional) faults and (2) WNW–ESE horizontal compression related to fault-block tectonics. The (older) NE-SW compression was most probably associated with the Late Cretaceous–Paleogene pan-regional basin inversion throughout Central Europe, as a reaction to ongoing African-Iberian-European convergence. Second WNW–ESE compression was active as of the Middle Miocene, at the latest, and might represent the Neogene–Quaternary tectonic regime of the NE Bohemian Massif. Exposed fault plane surfaces in a dissolution-collapse marble cave system provided insights into the Meso-Cenozoic tectonic history of the Earth’s uppermost crust in Central Europe, and were also identified as important guiding structures controlling the origin of the Niedźwiedzia Cave and the evolution of subsequent karstic conduits during the Late Cenozoic.

Norway Spruce (Picea abies L.) Evidencing >0.35 Ka Long Climate Variability in the Sudetes, Central Europe

“…During the Late Cretaceous, recurrent marine transgressions resulted in the formation of a >3 km thick sedimentary cover, subsequently removed during the Late Cretaceous-Cenozoic tectonic exhumation [13]. Late Cretaceous-Cenozoic tectonic activity resulted in bedrock jointing and faulting under compressional WNW-ESE conditions [14]. During the Paleogene, after the tectonic movements ceased, a regional peneplaine evolved, characterised by a generally flat and hilly landscape.…”

Damaged Speleothems and Collapsed Karst Chambers Indicate Paleoseismicity of the NE Bohemian Massif (Niedźwiedzia Cave, Poland)

“…During the Neogene (Late Miocene-Pliocene? ), active fault-block movements in the eastern part of the Śnieżnik Massif associated most-likely with WNW-ESE compressional regime (Sobczyk & Szczygieł, 2021) resulted in fluvial erosional cutting through strongly folded marbles of the Stronie formation and water-table cave formation. For the Quaternary (Pleistocene?)…”

“…Importantly, recent GNSS measurements combined with geological, geomorphological and geophysical data show significant, mainly dextral movements along the SMF (Roštínský et al, 2020). Within a range of 30-40 km from Niedźwiedzia Cave, one of the most seismically active structures is the Hronov-Pořiči Fault Zone (Sobczyk & Szczygieł, 2021), the easternmost part of the important central European tectonic structure-the Elbe Fault system (Málek et al, 2008). The Elbe Fault system contains mostly dextral NW-SE and NNW-SSEstriking faults and is suspected to be responsible for the most intense historical earthquakes in the NE Bohemian Massif (Špaček et al, 2006).…”

Fate and preservation of the Late Pleistocene cave bears from Niedźwiedzia Cave in Poland, through taphonomy, pathology, and geochemistry

“…The cave was formed within the marbles dated from Middle Cambrian to Early Ordovician (520–470 Ma) 2 . Their karstification began after the Paleogene basin inversion climax (65–45 Ma) 3 before its final post-Mid-Miocene uplift 4 . The karstification process in Kleśnica Valley aligned with WSW–ENE trending sub-vertical faults and fractures, with N–S to NNW–SSE steeply dipping foliation playing a subordinate role 5 .…”