Journal Article

A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

Bout-Roumazeilles, V., Kuhn, G., van de Flierdt, T., Sullivan, N. B., Hemming, S. R., Hillenbrand, C.-D., Dodd, J. P., Boshuis, C., Shevenell, A. E., Meyers, S. R., Licht, K. J., Marschalek, J. W., Harwood, D., Gasson, E., Pérez, L. F., van Peer, T. E., Carter, A., Beny, F., Kulhanek, D. K., Prebble, J. G., Browne, I., Perotti, M., McKay, R. M., Levy, R., Griffith, E. M., Zurli, L., Colleoni, F., Talarico, F., De Santis, L., Sangiorgi, F., Vermeesch, P., Siegert, M. J., Keisling, B.

2021

Overview

Early to Middle Miocene sea-level oscillations of approximately 40–60 m estimated from far-field records 1 – 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. Variations in Miocene sea level can be explained by a large marine-based West Antarctic Ice Sheet.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 704/106/125 / 704/106/413 / 704/2151/209 / Antarctic ice sheet / Antarctic Regions / Climate Models / Continental shelves / Cysts / Drilling / Environmental aspects / Environmental Sciences / Erosion rates / Geology / History, Ancient / Humanities and Social Sciences / Ice / Ice Cover / Ice sheet models / Ice sheets / Life Sciences / Lithology / Microorganisms / Miocene / multidisciplinary / Natural history / Neogene / Oscillations / Physics / Science / Science (multidisciplinary) / Sciences of the Universe / Sea level / Sea level oscillations / Sea Level Rise - history / Seawater - analysis / Sediments / Sheet modelling / Soil erosion