[MIS08-P12] Influence of Southern Ocean Intermediate water on the South Pacific’s thermocline during the last ~500 Ka
Keywords:Mg/Ca, Planktic Foraminifera, Intermediate waters, Stable isotopes
Here, we present ~500 ka multiproxy records of Mg/Ca ratios, clumped isotopes and stable oxygen isotope, measured on sea surface and thermocline-dwelling planktic foraminifera from the center of the SPG. The local salinity and Mg/Ca-temperature at the sea surface is relatively stable (~10 ºC) throughout the record. However, the dual proxy-based thermocline temperature records show two distinct climatic intervals. Prior to 300 ka, the conditions were cold and fresh, with average temperatures of ~4 ºC. Thereafter (<300 ka), the thermocline of the SPG became warmer and saltier, with average temperatures of ~8 ºC.
The SOIWs variability in the Pacific basin have been traditionally linked to the Southern Westerlies Winds. However, the evolution of the subsurface-temperature and -salinity substantially differs from the glacial-interglacial variability (position and/or intensity) of the Southern Westerlies Winds. We discuss several possible mechanisms that could lead to this enigmatic shift in our thermocline temperature and salinity records.