Surface and Subsurface Changes in the Indonesian Throughflow Region From the LGM to Present Inferred From G. ruber and P. obliquiloculata Mg/Ca and del 18O

The major climate phenomena in the Indo-Pacific Warm Pool, the El Niño-Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the monsoons, are all accompanied by significant changes in thermocline structure and temperature. Variations in ENSO, the IOD and the monsoons can influence the volume of the Indonesian Throughflow (ITF), the surface and thermocline water transported from the Pacific to the Indian Ocean through Indonesian gateways. These variations influence the heat and salinity budgets of both ocean basins. On short time scales, the temperature and depth of the thermocline in the Makassar Strait (Indonesia) correlate with the volume of ITF transported through the strait. In order to reconstruct past thermocline structure, we have measured the δ18O and Mg/Ca of surface mixed layer (G. ruber) and thermocline dwelling (P. obliquiloculata) foraminifera in several cores from the Makassar Strait and south of Java, near the exit of the ITF to the Indian Ocean. The records of G. ruber and P. obliquiloculata indicate changes in thermocline structure during both the deglaciation and Holocene. These changes occur simultaneously in several cores and indicate changes in regional climate that may have impacted the Throughflow transport.