Lithium Isotope Geochemistry in the Barton Peninsula, King George Island, Antarctica

• Published in: Frontiers in Earth Science
• Main Authors: Ryu, Jong-Sik, Lim, Hyoun, Soo, Choi, Hye-Bin, Kim, Ji-Hoon, Kim, Ok-Sun, Vigier, Nathalie
• Other Authors: Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Li isotopes; chemical weathering; meltwater; mineral neoformation; Antarctica; [SDU]Sciences of the Universe [physics]; Antarc*; King George Island
• Online Access: https://hal.science/hal-03864326; https://hal.science/hal-03864326/document; https://hal.science/hal-03864326/file/Ryu2022Frontiers.pdf; https://doi.org/10.3389/feart.2022.913687

International audience Lithium (Li) has two stable isotopes, 6 Li and 7 Li, whose large relative mass difference is responsible for significant isotopic fractionation during physico-chemical processes, allowing Li isotopes to be a good tracer of continental chemical weathering. Although physical erosion is dominant in the Polar regions due to glaciers, increasing global surface temperature may enhance chemical weathering, with possible consequences on carbon biogeochemical cycle and nutriment flux to the ocean. Here, we examined elemental and Li isotope geochemistry of meltwaters, suspended sediments, soils, and bedrocks in the Barton Peninsula, King George Island, Antarctica. Li concentrations range from 8.7 nM to 23.3 μM in waters, from 0.01 to 1.43 ppm in suspended sediments, from 9.56 to 36.9 ppm in soils, and from 0.42 to 28.3 ppm in bedrocks. δ 7 Li values are also variable, ranging from +16.4 to +41.1‰ in waters, from −0.4 to +13.4‰ in suspended sediments, from −2.5 to +6.9‰ in soils, and from −1.8 to +11.7‰ in bedrocks. Elemental and Li isotope geochemistry reveals that secondary phase formation during chemical weathering mainly control dissolved δ 7 Li values, rather than a mixing with sea salt inputs from atmosphere or ice melting. Likewise, δ 7 Li values of suspended sediments and soils lower than those of bedrocks indicate modern chemical weathering with mineral neoformation. This study suggests that increasing global surface temperature enhances modern chemical weathering in Antarctica, continuing to lower δ 7 Li values in meltwater with intense water-rock interactions.