A Large West Antarctic Ice Sheet Explains Early Neogene Sea-Level Amplitude

• Published in: Nature
• Main Authors: Marschalek, J., Zurli, L., Talarico, F., van de Flierdt, T., Vermeesch, P., Carter, A., Beny, F., Bout-Roumazeilles, V., Sangiorgi, F., Hemming, S., Pérez, L., Colleoni, F., Prebble, J., van Peer, T., Perotti, M., Shevenell, A., Browne, I., Kulhanek, D., Levy, R., Harwood, D., Sullivan, N., Meyers, S., Griffith, E., Hillenbrand, C.-D., Gasson, E., Siegert, M., Keisling, B., Licht, K., Kuhn, G., Dodd, J., Boshuis, C., de Santis, L., Mckay, R.
• Other Authors: Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Nord )
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDE]Environmental Sciences; [SDU]Sciences of the Universe [physics]; [SDV]Life Sciences [q-bio]; [PHYS]Physics [physics]; Antarctic; East Antarctica; Ross Sea; West Antarctic Ice Sheet; West Antarctica; Antarc*; Antarctica; Ice Sheet
• Online Access: https://sde.hal.science/hal-03796588; https://sde.hal.science/hal-03796588/document; https://sde.hal.science/hal-03796588/file/Marschalek_Main_Final-1.pdf; https://doi.org/10.1038/s41586-021-04148-0

International audience Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from farfield records 1,2,3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth 2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene 4,5. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here, we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution.