Early deglaciation and paleolake history of Rio Cisnes Glacier, Patagonian Ice Sheet (44°S)
Garcia, Juan-Luis
Pontificia Universidad Catolica de Chile
Maldonado, Antonio
Ctr Estudios Avanzados Zonas Aridas
de Porras, Maria Eugenia
Ctr Estudios Avanzados Zonas Aridas
Delaunay, Amalia Nuevo
Ctr Invest Ecosistemas Patagonia
Ebensperger, Claudia A.
Pontificia Universidad Catolica de Chile
Binnie, Steven A.
University of Cologne
Luethgens, Christopher
BOKU University
Mendez, Cesar
Ctr Invest Ecosistemas Patagonia
Journal
Quaternary Research (United States)
ISSN
0033-5894
1096-0287
Open Access
closed
Volume
91
Start page
194
End page
217
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 Rio Cisnes Glacier at 44 degrees S and also from the nearby Rio Nirehuao and Rio El Toqui valleys (45 degrees S) in Chilean Patagonia. Our C-14, Be-10, and optically stimulated luminescence data indicate that after the last glacial maximum, Rio 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, Rio Cisnes Glacier extended only 40% of its full glacial extent. The deglaciation of Rio 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.