Early deglaciation and paleolake history of Río Cisnes Glacier, Patagonian Ice Sheet (44°S)

• Published in: Quaternary Research
• Main Authors: García, Juan-Luis, Maldonado, Antonio, de Porras, María Eugenia, Nuevo Delaunay, Amalia, Reyes, Omar, Ebensperger, Claudia A., Binnie, Steven A., Lüthgens, Christopher, Méndez, César
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2018
• Subjects: Antarc*; Antarctic; Antarctica; Ice Sheet; Sea ice; Southern Ocean; West Antarctica
• Online Access: http://dx.doi.org/10.1017/qua.2018.93; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589418000935

Abstract The timing, structure, and landscape change during the Patagonian Ice Sheet deglaciation remains unresolved. In this article, we provide a geomorphic, stratigraphic, and geochronological deglacial record of Río Cisnes Glacier at 44°S and also from the nearby Río Ñirehuao and Río El Toqui valleys (45°S) in Chilean Patagonia. Our 14 C, 10 Be, and optically stimulated luminescence data indicate that after the last glacial maximum, Río Cisnes Glacier experienced ~100 km deglaciation between >19.0 and 12.3 ka, accompanied by the formation of large glacial paleolakes. Deglaciation was interrupted by several ice readvances, and by 16.9±0.3 ka, Río Cisnes Glacier extended only ~40% of its full glacial extent. The deglaciation of Río Cisnes Glacier and other sensitive Patagonian glaciers occurred at least 1 ka earlier than the ca. 17.8 ka normally assumed for the local termination, coincident with West Antarctic isotope records. This early deglaciation can be linked to an orbital forcing–driven decline of Southern Ocean sea ice associated with a distinct atmospheric warming that is apparent for West Antarctica through Patagonia.