Decoupled dust deposition and ocean productivity in the Antarctic Zone of the Southern Ocean

Weber, Michael E.; Bailey, Ian; Hemming, Sidney; Martos, Yasmina M.; Reilly, Brendan; Ronge, Thomas A.; Brachfeld, Stefanie; Williams, Trevor; Raymo, Maureen; Belt, Simon T.; Smik, Lukas; Vogel, Hendrik; Peck, Victoria; Armbrecht, Linda; Cage, Alix; Bardillo, Fabricio G.; Du, Zhiheng; Fauth, Gerson; Fogwill, C.J.; García, Marga; Garnsworthy, Marlo; Glueder, Anna; Guitard, Michelle; Gutjahr, Marcus; Hernández-Almeida, Iván; Hoem, Frida; Hwang, Ji-Hwan; Iizuka, Mutsumi; Kato, Yuji; Kenlee, Bridget; Oconnell, Suzanne; Pérez, Lara F.; Seki, Osamu; Stevens, Lee; Tauxe, Lisa; Tripathi, Shubham; Warnock, Jonathan P; Zheng, Xufeng

Abstract

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.

• Conference Name: GeoKarlsruhe
• Conference Location: Karlsruhe, Germany
• Start Date: Sep 19, 2021
• End Date: Sep 24, 2021
• Acceptance Date: Sep 19, 2021
• Online Publication Date: Sep 19, 2021
• Publication Date: Sep 19, 2021
• Deposit Date: May 30, 2023