Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years
Michael E Weber, Ian Bailey, Sidney R. Hemming, Yasmina M. Martos, Brendan T. Reilly, Thomas A. Ronge, Stefanie Brachfeld, Trevor Williams, Maureen E. Raymo, Simon T. Belt, Lukas Smik, Hendrik Vogel, Victoria L. Peck, Linda Armbrecht, Alix G. Cage, F.G. Cardillo, Zhiheng Du, Gérson Fauth, Christopher J. Fogwill, Marga García, Marlo Garnsworthy, Anna Glüder, Michelle Guitard, Marcus Gutjahr, Iván Hernández‐Almeida, Frida S. Hoem, Ji‐Hwan Hwang, Mutsumi Iizuka, Yuji Katō, Bridget Kenlee, Suzanne O’Connell, Lara F. Pérez, Osamu Seki, Lee A. Stevens, Lisa Tauxe, Shubham Tripathi, Jonathan Warnock, Xufeng Zheng
Abstract
Abstract The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO 2 levels.