Discovery and dating of Pre-LGM deposits in a high catchment of the Dolomites (Italy): New insights on climate-related geomorphological processes during the Late Pleistocene

The results from the analysis of a relatively deep stratigraphic sequence from a formerly glaciated plateau in the Upper Badia valley (Dolomites, Italy) are discussed, and the first insight on Late Pleistocene sedimentary records and geomorphological evolution of the area are provided. The investigated sequence comprises: i) cohesive sediments interpreted as colluvial-eluvial in origin or as stagnant water deposits; ii) sandy diamicton and dolostone monolithic sediments interpreted as gravity-induced deposits, possibly owing to debris flows or wash out/ reworking of rock avalanche deposits from the surrounding dolomite ridges; iii) silty diamicton interpreted as lodgement till, possibly attributed to the Last Glacial Maximum (LGM). Radiocarbon dating results and interpretation of stratigraphic data, supported by geomorphological field surveys, remote sensing data analyses and palaeoclimatic and palaeo-environmental data from literature, enabled us to conclude that the investigated plateau (Pralongià, ca. 2000 m a.s.l.) was likely ice-free for most of Marine Isotope Stage 3. In particular, between 38 ka BP
and the inset of full-glacial conditions (LGM ~ 27 ka BP) clastic gravity-induced sediments were deposited within the study site. Supraglacial transport is supposed to have played a role in the emplacement of gravity-induced deposits fromthe surrounding dolomite cliffs to the plateau. This study resulted in the first Pre-LGM record of sedimentation and palaeo-environmental conditions inside the Eastern Dolomites in the 46 to 38 ka BP period.