Opposite Dust Grain Size Patterns in the Pacific and Atlantic Sectors of the Southern Ocean During the Last 260,000 Years

• Main Authors: van der Does, Michèlle, Wengler, Marc, Lamy, Frank, Martinez-Garcia, Alfredo, Kuhn, Gerhard, Stuut, Jan-Berend, Tiedemann, Ralf, Winckler, Gisela
• Format: Conference Object
• Language: unknown
• Published: AGU 2020
• Subjects: Antarctic; Southern Ocean; Pacific; Antarc*
• Online Access: https://epic.awi.de/id/eprint/53465/; https://hdl.handle.net/10013/epic.7fcc453e-db0b-42c3-be7b-6fbe7b017bdb

Southern Ocean westerly wind intensity and position are thought to play a crucial role in controlling glacial/interglacial CO2 changes through their impact on Antarctic upwelling intensity and the delivery of iron-rich dust that stimulates biological production during glacial periods. Sediment-core grain size records can provide key insights into changes in wind strength and source-area characteristics over glacial-interglacial timescales. However, so far, little is known about G/IG grain size changes in Southern Ocean sediments. For this study, we analyzed the grain-size distributions of two subantarctic deep sea sediments cores from the Pacific (PS75/056-1) and Atlantic (ODP Site 1090) sectors of the Southern Ocean. Dust mean grain size shows opposing trends in the two Southern Ocean sectors. Coarser glacial grain sizes are observed in the Pacific sector, while finer glacial grain-sizes are observed in the Atlantic. Our results suggest that changes in the latitudinal position of the SWW had distinct impacts on grain size distribution in the Atlantic and Pacific sectors, also likely associated with shifts in the dust source areas. These findings indicate that more extensive studies of grain-size distribution in the Southern Ocean can provide important insights on the timing and latitudinal extent of the westerly winds changes during ice ages.