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Title: Decoupled dust deposition and ocean productivity in the Antarctic Zone of the Southern Ocean over the past 1.5 million years

Authors:
Michael E. Weber1, Ian Bailey2, Sidney R. Hemming3, Yasmina M. Martos4,5, Brendan T. Reilly6, Thomas A. Ronge7, Stefanie Brachfeld8, Trevor Williams9, Maureen Raymo3, Simon T. Belt10, Lukas Smik10, Hendrik Vogel11, Victoria Peck12, Linda Armbrecht13, Alix Cage14, Fabricio G. Cardillo15, Zhiheng Du16, Gerson Fauth17, Christopher J. Fogwill14,18, Marga Garcia19,20, Marlo Garnsworthy21, Anna Glüder22, Michelle Guitard23, Marcus Gutjahr24, Iván Hernández-Almeida25, Frida S. Hoem26, Ji-Hwan Hwang27, Mutsumiq Iizuka28, Yuji Kato29, Bridget Kenlee30, Suzanne OConnell31, Lara F. Pérez12, Osamu Seki32, Lee Stevens33, Lisa Tauxe6, Shubham Tripathi34, Jonathan Warnock35, Xufeng Zheng36

Institutions:
1University of Bonn, Institute for Geosciences, Germany; 2Camborne School of Mines and Environmental Sustainability Institute, University of Exeter, Penryn Campus, Treliever Road, Cornwall TR10 9FE, UK; 3Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA; 4NASA Goddard Space Flight Center, Planetary Magnetospheres Laboratory, Greenbelt, MD 20771, USA; 5University of Maryland, Department of Astronomy, College Park, MD 20742, College Park, USA; 6Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA; 7Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27568 Bremerhaven, Germany; 8Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, USA; 9International Ocean Discovery Program, Texas AM University, College Station, TX 77845, USA; 10School of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth, PL4 8AA, UK; 11Oeschger Centre for Climate Change Research, University of Bern, Switzerland; 12British Antarctic Survey, Cambridge CB3 0ET, UK; 13Australian Centre for Ancient DNA, Department of Ecology & Evolutionary Biology, University of Adelaide, South Australia 5005, Australia; 14School of Geography, Geology and the Environment, University of Keele, Staffordshire, UK; 15Departmento Oceanografia, Servicio de Hidrografia Naval, Ministerio de Defensa, Argentina; 16State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Lanzhou 730000, China; 17Geology Program, University of Vale do Rio dos Sinos, San Leopoldo RS 93022-750, Brazil; 18School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia; 19Andalusian Institute of Earth Science (CSIC-UGR). Armilla (Granada) 18100 Spain; 20Spanish Institute of Oceanography, Cádiz 11006, Spain; 21Wordy Bird Studio, Wake Field, Rhode Island, USA; 22College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA; 23College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA; 24GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany; 25Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland; 26Department of Earth Science, MarineMarine Palynology and Paleoceanography, Utrecht University, 3584 CB Utrecht, Netherlands; 27Earth Environmental Sciences, Korea Basic Science Institute, Chungbuk Cheongju, Republic of Korea; 28Knowledge Engineering, Tokyo City University, Tokyo setagaya-ku 158-0087, Japan; 29Center for Advanced Marine Core Research, Kochi University, Nankoku, Kochi 783-8502, Japan; 30Department of Earth Sciences, University of California Riverside, Riverside, CA 92521, USA; 31Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459, USA; 32Institute of Low Temperature Science, Hokkaido University, Sapporo Hokkaido 060-0819, Japan; 33American Museum of Natural History, 200 Central Park West, New York NY 10024, USA; 34Marine Stable Isotope Lab, National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco Da Gama 403804, India; 35Department of Geoscience, Indiana University of Pennsylvania, Indiana, PA 15705, USA; 36South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China

Event: GeoKarlsruhe 2021

Date: 2021

DOI: 10.48380/dggv-qb53-0598

Summary:
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 the first 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 ≥10-fold increase in dust deposition during glacials and a ≤5-fold increase in ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more widespread across the Mid-Pleistocene Transition (MPT) and, at ~0.9 Ma, dominant ice-age cycles changed from 40,000 to 100,000-years, suggesting more severe glaciations thereafter. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels.



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