Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5–11.7 ka): diatom-inferred δ18O values and hydro-isotopic modeling

• Published in: Quaternary Science Reviews
• Main Authors: Quesada, Benjamin, Sylvestre, Florence, Vimeux, Françoise, Black, Jessica, Paillès, Christine, Sonzogni, Corinne, Alexandre, Anne, Blard, Pierre-Henri, Tonetto, Alain, Mazur, Jean-Charles, Bruneton, Hélène
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), Institut de Recherche pour le Développement (IRD), Hydrosciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Aix-Marseille Université - Faculté des Sciences (AMU SCI), Aix Marseille Université (AMU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDE]Environmental Sciences; Ice cap
• Online Access: https://hal.science/hal-01909526; https://hal.science/hal-01909526/document; https://hal.science/hal-01909526/file/Quesada%20et%20al.,%202015.pdf; https://doi.org/10.1016/j.quascirev.2015.04.022

International audience During the last deglaciation, the Bolivian Altiplano (15e23 S, 66e70 W) was occupied by paleolake Tauca covering, at least, ~51,000 km 2 at its maximum highstand between 16.5 and 15 ka. Twenty-five hundred years later, after a massive regression, a new transgressive phase, produced paleolake Coi-pasa, smaller than Tauca and restricted to the southern part of the basin. These paleolakes were overlooked at the west by the Sajama ice cap. The latter provides a continuous record of the oxygen isotopic composition of paleo-precipitation for the last 25 ka. Contemporaneously to the end of paleolake Tauca, around 14.3 ka, the Sajama ice cap recorded a significant increase in ice oxygen isotopic composition (d 18 O ice). This paper examines to what extent the disappearance of Lake Tauca contributed to precipitation on the Sajama summit and this specific isotopic variation. The water d 18 O values of paleolakes Tauca and Coipasa (d 18 O lake) were quantitatively reconstructed from 18.5 to 11.7 ka based on diatom isotopic composition (d 18 O diatoms) and ostracod isotopic composition (d 18 O carbonates) retrieved in lacus-trine sediments. At a centennial time scale, a strong trend appears: abrupt decreases of d 18 O lake during lake fillings are immediately followed by abrupt increases of d 18 O lake during lake level stable phases. The highest variation occurred at ~15.8 ka with a d 18 O lake decrease of about ~10‰, concomitant with the Lake Tauca highstand, followed ~400 years later by a 7‰ increase in d 18 O lake. A simple hydro-isotopic modeling approach reproduces consistently this rapid "decreaseeincrease" feature. Moreover, it suggests that this unexpected re-increase in d 18 O lake after filling phases can be partly explained by an equilibration of isotopic fluxes during the lake steady-state. Based on isotopic calculations during lake evaporation and a simple water stable isotopes balance between potential moisture sources at Sajama (advection versus lake evaporation), we show that total ...