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

Ilaria Isola,Eleonora Regattieri,Giancarlo Molli,Leonardo Piccini,John Hellstrom,Flavio Milazzo,Jon Woodhead,Russell Drysdale,Diego Pieruccioni,Adriano Roncioni,Giovanni Zanchetta,Francesco Mazzarini,Elena Zanella

doi:10.3390/geosciences11020065

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.

Highlights

IntroductionA number of studies investigated the complex tectonic evolution of the region (e.g., [1,2,3] and reference therein), including the exhumation history and its relationship with the orogenesis of this sector of the Apennine chain, mainly through thermochronology methods (e.g., [4,5,6,7,8])
We describe here fluvial deposits preserved within the Galleria delle Stalattiti (GdS), which belongs to one of the major horizontal passage systems of the Corchia Cave complex
Cave,Cave, we proUsingrobust robustdating dating from independent hypogean deposits in Corchia the Corchia we vide new information about the tectonic uplift of the Apuane since the lower

Summary

Introduction

A number of studies investigated the complex tectonic evolution of the region (e.g., [1,2,3] and reference therein), including the exhumation history and its relationship with the orogenesis of this sector of the Apennine chain, mainly through thermochronology methods (e.g., [4,5,6,7,8]). Thermochronology is the quantitative study of the thermal history of rocks using temperaturesensitive radiometric dating [9]. Other chronological constraints on paleotectonic evolution of mountain ranges can be provided by alluvial deposits preserved in river terraces located at different altitudes, but their formation is often strongly affected by climate variations, and so they are not directly related to tectonically induced base-level changes and their chronology is, difficult to be defined in detail. Caves can provide additional quantitative constraints on the vertical displacement of a subterranean hydrologic system relative to its base level [11,12,13,14]

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Discussion

Conclusion