Reis: U.S. Science Support Program Office associated with the International Ocean Discovery Program (USSSP-IODP)

This project proposes to use calcium and silicon stable isotopes and trace element analysis of pore waters and sediment to examine the South Pacific establishment of the Antarctic Circumpolar Current (ACC). As the warm, sub-tropical waters of the East Australian Current were replaced by the cold waters of the ACC, a transition from a silica-dominated system to a carbonate-dominated system is observed. This shift likely reflects changes in both productivity and sediment preservation. Variations in calcium and silicon isotopic ratios capture these changes, specifically providing a record of the dissolution history. Additionally, the timing of isotopic ratio shifts, particularly in relation to observed faunal changes, should clarify the drivers of Neogene hiatuses in the South Pacific.