Reduction in the Strength of Agulhas Current During Quaternary: Planktic Foraminiferal Records for 1.2 Million Years from IODP Hole U-1474A

Abstract

The Agulhas Current (AC) had been quite variable during the Quaternary Period, which not only impacted the Agulhas Leakage (AL) but also caused changes in the AMOC. To study the changes in the strength of AC, planktic foraminiferal census count and stable oxygen isotope data from the IODP Hole U-1474A were generated for the last 1.2 million years (My). We recorded significant variations in the abundance of climate-sensitive species, which were grouped according to their ecological preference as warm tropical-subtropical Agulhas Fauna (AF), temperate-subpolar Southern Ocean Fauna (SOF), stable oxygen isotope records and the Subtropical Front (STF) Index. The correlation of these records suggests that the strength of AC reduced during seven intervals during the last 1.2 My, in response to cooling climate, which led to the northward shift of STF. The studied interval was divided into three periods of MPT, MPT-MBE and post-MBE events. The AC was strongest after the Mid-Brunhes Event (0.43 Ma) as compared to the Mid-Pleistocene Transition (MPT) and post-MPT to MBE intervals.