Geomorphic Records along the General Carrera (Chile)–Buenos Aires (Argentina) Glacial Lake (46°-48°S), Climate Inferences, and Glacial Rebound for the Past 7–9ka

• Published in: The Journal of Geology
• Main Authors: Bourgois, Jacques, Cisternas, Maria Eugenia, Braucher, Regis, Bourles, Didier, Frutos, José
• Other Authors: Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Instituto de Geologia Economica Aplicada, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), San Juan de Luz 4060
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Argentina; Carrera; Glacial Lake; Patagonia; Ice Sheet
• Online Access: https://hal.science/hal-01271536; https://hal.science/hal-01271536/document; https://hal.science/hal-01271536/file/80509%282%29.pdf; https://doi.org/10.1086/684252

International audience We present geomorphic, stratigraphic, and chronological data acquired along the General Carrera-Buenos Aires (GCBA) glacial lake located along a majormorphological incision across the Andes. Complementing relevant available data, relative chronology of morpho-climatic records together with 18 10Be Cosmic Ray Exposure (CRE) ages allow constraining the timing of the Patagonian ice-sheet fluctuations since the LGM. It improves the knowledge of the Patagonia climate evolution in the 46-48°S area, and allows documenting the uplift rates (glacial rebound) for the past ~7-9 ka. The first major ice lobe retreat occurred after 17.3 ± 0.6 ka and has likely continued during the ACR from ~12.9 to 14.5 ka. Between ~12.9 ka and ~10.9 ± 1.3 ka, the General Carrera Lake evolved as an endorheic basin. Terraces T4 to T1 (top to bottom) have recorded abrupt lake regressions likely controlled by rainfalldeficit. They have accumulated in the time interval ~17.3-12.3 ka (maximum limits). Two glacial re-advances at ~10.9 ± 1.3 and ~7.9 ± 1.1 ka marked a major climate change that led the lake to be ice-dammed again. A major transgression occurred subsequently that have flooded the previously accumulated terraces. Since then, a pervasive regression has steered the GCBA Lake to the situation at Present. The highest shoreline of the transgression is used as a passive marker in order to quantify the magnitude and character of the regional deformation. At 72°30' W, the GCBA Lakearea uplifted (glacial rebound) at a rate between 15 to 33.5 mm.yr--1 during the past ~7.9 ± 1.1 ka. We infer that the high uplift rate mainly originates from the North Patagonian icefield ice loss.