TERRIGENOUS CLAY COMPOSITION IN THE SOUTH ATLANTIC AT IODP SITE U1558 AND ITS IMPLICATIONS FOR OCEAN CIRCULATION AND CRYOSPHERE DEVELOPMENT

The Eocene-Oligocene transition marks the inception of permanent continental scale ice sheets in Antarctica. By combining a polar record in the Weddell Sea region and a mid-latitude record of the south Atlantic, this work aims to characterize the terrigenous materials in the South Atlantic in the context of Antarctic cryosphere development and its implications on ocean circulation. The recently drilled IODP South Atlantic Transect recovered the EOT at Site U1558 and presents the opportunity to track the introduction of Antarctic Bottom Waters to the site. The E-O transition sediments at this site are characterized by increased clay content, darkening of sediment color, higher magnetic susceptibility, and lower CaCO₃ content. Previous work on the terrigenous sortable silt suggests increases in sortable silt precent and mean sortable silt point to the introduction of this water mass to the site. An increase in chlorite at the site would signal a water mass originating from the polar regions, as the highest chlorite concentrations in marine sediments in the South Atlantic are located under the Antarctic Circumpolar Current (ACC). A record of terrigenous clay composition will work to confirm this hypothesis by determining the origin of the water bathing site U1558 at the Eocene-Oligocene transition.