Late Pleistocene glacial history of the Ivrea Morainic Amphitheatre, western Italian Alps

Geochronological constraints from glacial sedimentary deposits and landforms worldwide indicate that ice maxima occurred asynchronously throughout the Late Pleistocene1, often before the global Last Glacial Maximum2 (LGM; Marine Isotope Stage, MIS 2). Within the European Alps, the work of Gribenski et al. (2021)3 recently shed light on such pre-LGM (MIS 4 and late MIS 3) ‘local’ ice maxima in the western Alps, pre-dating the ice culmination in the central northern and southern Alps4, 5. This asynchrony is interpreted to result from changes in the atmospheric circulation pattern over the North Atlantic3. However, more data are needed to further corroborate this hypothesis and increase our understanding of the paleoglacial and paleoclimate dynamics of the western Alps. The Ivrea Morainic Amphitheatre (IMA; western Italian Alps) is a promising site to investigate the potential asynchrony of Late Pleistocene glaciations. This extensive end-moraine complex was built by the cyclic Quaternary expansions of the Dora Baltea glacier in the southern Alpine foreland. However, the available geochronological data6, 7 are too limited to quantitatively attribute each sub-system of moraines to different glacial advances. The present work aims to provide new chronological constraints to the innermost glaciogenic succession of the IMA. To this aim, luminescence dating is applied on proglacial glaciolacustrine and glaciofluvial deposits associated to different stages of ice advance. The obtained chronology (ca. 30 samples) provides new insights into the Late Pleistocene glacial history of one of the largest morainic amphitheatre in the European Alps, contributing to the ongoing discussion on asynchronous paleoglacial dynamics during this period.