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Wet-based mountain glaciers are efficient agents of erosion, which leads to the assumption that each glacial episode results in successive valley deepening. The tendency of subsequent glaciations to obscure evidence of previous events makes it difficult to study the work done by past glacial episodes. Epiphreatic and paleophreatic caves that developed at or under the water table and dried out in response to valley deepening can serve as recorders of the valley incision history. U-series data from speleothems in the cave networks at the base of the present-day valleys in the Tatra Mountains (Western Carpathians) consistently yield the oldest ages of ca. 325 ka. While speleothem ages are typically phreatic-vadose transition minimum ages, they nonetheless unequivocally demonstrate that neither glacial valley deepening nor fluvial incision occurred over the past 300 ka, unlike the successive valley deepening over the same period in the adjacent Alps. [ABSTRACT FROM AUTHOR]

The steep morphology, highest elevation within the Carpathians, and distinct fault borders of the Tatra Mts. support the assumption of recent tectonic activity. However, for decades, the Quaternary tectonic activity of the Tatra Mts. has been poorly evidenced, and a late Pleistocene fault rupture was discovered recently. Using the protected environment of the caves, we have utilized 230Th/U dating of damaged speleothems to extend the record of Quaternary deformation of the Tatra Mts. up to 0.5 Ma. The results from ten caves reveal five periods of increased activity at 465–332, 280–260, 204.8–188.8, 127–86.6, and 29.5–10.11 ka ago. Three mechanisms of fault reactivation were identified through paleostress analysis of cave passage offsets: (1) gravitational sliding; (2) NNE–SSW transpression, likely associated with the Alps–Carpathians–Pannonian (ALCAPA) NNE motion; and (3) tectonic-driven SE-trending compression that reactivated the strike–slip and the gently dipping oblique lower-order faults. The geochronological data indicate that these three stress regimes operated during the late Pleistocene; however, our fault-slip data do not allow us to identify the dominant process. Herein, we suggest that the fault slip was caused by the isostatic response of the Tatra block to the unloading of mountain glaciers, coupled with sediment evacuation overlapping with regional-scale tectonic processes. These processes are locally obliterated by debuttressing. We also show that the distances between the caves and possible seismic sources (i.e., the Sub-Tatric and Ružbachy faults) are sufficiently short to break speleothems in response to oscillation. Given that for most caves an earthquake of >M w 6.5 would be destructive, it seems co-seismic deformations in caves are highly likely considering the M w > 7 potential of the Sub-Tatric Fault. • Multiphase cave-conduit offsets in the Tatra Mts. were analyzed. • Dating damage-related speleothems revealed five periods of increased activity. • The two fault sets were likely reactivated due to the overlap of the isostatic rebound and Alpine–Carpathian–Pannonian push. • Some faults were reactivated due to slope response to the retreats of Pleistocene glaciers. [ABSTRACT FROM AUTHOR]