Reconstructing the late-Quaternary glacial history of northeastern Patagonia (43°S, 71°W): new insights from geomorphology, geochronology and numerical glacier modelling

• Main Author: Leger, Tancrède P. M.
• Other Authors: Hein, Andrew, Bingham, Robert, Nienow, Peter, Natural Environment Research Council (NERC), Scottish Alliance for Geoscience Environment and Society, UK Quaternary Research Association, British Society for Geomorphology, University of Edinburgh School of GeoSciences
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: The University of Edinburgh 2022
• Subjects: Patagonia; Quaternary period; Quaternary climate change; Patagonian glaciers; surface exposure dating; Antarctic; The Antarctic; Huemul; Antarc*; Ice Sheet
• Online Access: https://hdl.handle.net/1842/39546; https://doi.org/10.7488/era/2796

Former investigations conducting geomorphological mapping of Patagonia, a region formerly covered by an extensive ice sheet, have revealed a uniquely rich record of Quaternary glacial sediment-landform assemblages. Patagonia is located in the ocean-dominated southern mid-latitudes and in the pathway of major southern hemisphere circulation systems including the precipitation-bearing southern westerly winds, and the Antarctic circumpolar current. For these reasons, Quaternary glacier reconstructions from Patagonia can help identify the main drivers of climate and glacial events in the Southern Hemisphere. However, in northeastern Patagonia (39-46°S), geochronological data addressing the precise timing of Quaternary glacial events during Pleistocene glacial cycles are lacking. Indeed, in this region, little is known about the magnitude and timing of the Patagonian Ice Sheet’s response to climate events such as, for instance, the local Last Glacial Maximum (lLGM) and the last glacial termination. This Ph.D investigation attempted to fill in this knowledge gap, by producing a robust geochronological reconstruction that would describe the extent, stratigraphic relationship, characteristics and precise timing of most Quaternary glacial events preserved in a key valley system formerly host to major outlet glaciers of the northern Patagonian Ice Sheet. Firstly, this thesis presents the first detailed glacial geomorphological map of the Río Corcovado, Río Huemul and Lago Palena/General Vintter valleys (43°S; 71°W). This mapping effort enabled the identification of 25 distinct categories of sediment-landform assemblages related to the glaciogenic, glaciofluvial and glaciolacustrine activity of the former Patagonian Ice Sheet. This work revealed the preservation of at least eight distinct moraine-outwash complexes at the study site, each indicative of a former outlet-glacier advance/still-stand. Secondly, this thesis provides a new terrestrial cosmogenic nuclide exposure age (n = 38) chronology that establishes the precise ...