New Chronological Constraints from Hypogean Deposits for Late Pliocene to Recent Morphotectonic History of the Alpi Apuane (NW Tuscany, Italy)

Abstract: A sedimentary sequence of fluvial deposits preserved in the Corchia Cave (Alpi Apuane)
provides new chronological constraints for the evolution of the cave system and the timing and rate
of uplift of this sector of the Alpi Apuane since the late Pliocene. Supported by magnetostratigraphic
analysis performed on fine-grained fluvial deposits, and by radiometric dating of speleothems, we
suggest that the deposition of fluvial sediments occurred between ~1.6–1.2 Ma. This implies that the
host volume of rock was already located close to the local base level, adding key information about
the recent tectonic evolution of the Alpi Apuane. A few before ~1 Ma, an erosive phase occurred
due to the base-level lowering, followed by continuous speleothem deposition since at least 0.97 Ma.
From that time, Monte Corchia uplifted at a maximum rate of ~0.5 mm/year, which is consistent
with isostatic uplift mainly driven by erosional unloading. The petrographical study of the fluvial
deposits highlights the presence of material derived from the erosion of rocks that today are absent
in the cave’s catchment area, suggesting a different surface morphology during the Early Pleistocene.
This study highlights the potential of cave sediments as archives for reconstructing the uplift history
of mountain ranges.