Major deglaciation during the Late Glacial in coastal regions of Greenland

The Greenland Ice Sheet (GrIS) is a key component of the global climate system. However, our current understanding of the spatio-temporal oscillations and landscape transformation of the GrIS margins since the last glacial cycle is still incomplete. This work aims to study the deglaciation in the Zackenberg Valley, Greenland, and the origin of the derived glacial landforms. In order to reconstruct the spatial extent and geometry of past glacial phases we carried out extensive fieldwork and high-detailed geomorphological mapping, together with cosmic-ray exposure (CRE) dating to samples from erosive and depositional glacial landforms. Erratic boulders dispersed across the summits suggest that Late Quaternary glaciers filled the valleys and fjords during periods of maximum ice expansion. As glacier thickness decreased, the Zackenberg glacier was confined in the interior of the main valley, leaving several lateral moraine ridges along the slopes. The deglaciation started by ~13.7-12.5 ka and accelerated paraglacial slope processes (e.g. solifluction). By ca. 10.5 ka, the last remnants of glacial ice disappeared from the lower sections of the valley. This deglaciation chronology broadly agrees with what is observed in other sites across Greenland.