Late Glacial deglaciation of the Zackenberg area, NE Greenland

• Published in: Geomorphology (Amsterdam, Netherlands) Vol. 401; p. 108125
• Main Authors: Garcia-Oteyza, J., Oliva, M., Palacios, D., Fernández-Fernández, J.M., Schimmelpfennig, I., Andrés, N., Antoniades, D., Christiansen, H.H., Humlum, O., Léanni, L., Jomelli, V., Ruiz-Fernández, J., Rinterknecht, V., Lane, T.P., Adamson, K., Aumaître, Georges, Bourlès, Didier, Keddadouche, Karim
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.03.2022; Elsevier
• Subjects: Cosmic-ray exposure; Deglaciation; Earth Sciences; Geomorphology; NE Greenland; Paraglacial dynamics; Sciences of the Universe; Zackenberg; Geomorphology; Cosmic-ray exposure; Zackenberg; Deglaciation; NE Greenland; Paraglacial dynamics
• ISSN: 0169-555X; 1872-695X
• DOI: 10.1016/j.geomorph.2022.108125

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. The objective of this work is to study the deglaciation of the Zackenberg Valley (74°N, 20°E), NE Greenland, and the origin of the derived landforms. Based on extensive fieldwork and high-detail geomorphological mapping we identified the different types of landforms, from which those of glacial and paraglacial origin were used to understand the processes driving regional environmental evolution. We applied cosmic-ray exposure (CRE) dating to 32 samples taken from erosive and depositional glacial landforms distributed across the valley. Geomorphological evidence shows that >800-m-thick Late Quaternary glacier filled the valleys and fjords and covered mountain summits. In subsequent phases, as ice thickness decreased, the glacier was limited to the interior of the valley, leaving several lateral moraines. The deglaciation of the Zackenberg Valley that started by ~13.7–12.5 ka also accelerated slope paraglacial processes. Many blocks from lateral moraines were remobilized and fell, reaching the valley floor where they covered the thinning glacier tongue; transforming it into a debris-covered glacier that subsequently melted gradually. By ca. 10.5 ka, the last remnants of glacial ice disappeared from the Zackenberg Valley floor, a chronology of deglaciation that is similar to that observed in other sites across NE Greenland. The results of this work must be considered in similar studies, reinforcing the need to support CRE ages of the different geomorphological phases with paleoclimatic data from other sedimentary records. •We reconstruct the deglaciation of the Greenland Ice Sheet in the Zackenberg Valley.•Local summits were ice-free at ca. 80-50 ka, prior to the Last Glacial Maximum.•The long-term GrIS recession was interrupted by short periods of stillstand or glacial advance during T-1 between 13.7 and 11.2 ka.•Since the Early Holocene (ca. 10.5 ka), no glaciers have existed in the Zackenberg Valley.