Cosmogenic dating reveals the timing of glaciers collapse in the high Dolomites valleys (Northern Italy)

Abstract

During the Last Glacial Maximum (LGM) the Italian Alps were extensively ice-covered with icefields feeding a network of interconnected valley glaciers and piedmont glaciers spilling into the foreland. The subsequent Lateglacial ice retreat occurred with different modes and timing across the region. This paper arises from the need for further investigation to better understand the glaciers' dynamics of the period and focuses on the glacial history of the Alta Badia valley (Eastern Dolomites, Italian Alps) as a key area for reconstructing the LGM glaciers' collapse and Lateglacial readvances within the region. We present a reconstruction of LGM and Lateglacial glaciers' evolution supported by cosmogenic ³⁶Cl surface exposure data - obtained for the first time in the area - and geomorphological evidence. Our findings suggest that LGM ice retreat began before 17 ka BP. Within a general trend of ice decay, we identified the Gschnitz readvance from reconstructed glacier surfaces and Equilibrium Line Altitude (ELA) estimates, supported by moraine dating (15.8–15.4 ka BP) in the southeastern sector of the valley. Similarly, a Lateglacial readvance corresponding to the traditional Daun Readvance was recognized in the southwestern sector, based on exposure ages (14.4 and 13.3 ka BP) and calculated ELA. Evidence indicates that after the Daun phase, the valley was nearly deglaciated, retaining only small glacial remnants at higher elevations. This study enhances our understanding of LGM ice retreat and Lateglacial chronology, providing insights into the Alpine glacial history and establishing a foundation for estimating paleoclimatic conditions of the region.