SEA SURFACE TEMPERATURE AND PRODUCTIVITY RECORDS FROM A LATITUDINAL TRANSECT OF NORTH ATLANTIC SITES DURING THE PLIO-PLEISTOCENE TRANSITION

During the Plio-Pleistocene transition (4 Ma to the present) a pronounced global cooling occurred, which was marked by the rapid glaciation of the northern hemisphere. In this study, we generated alkenone-derived sea surface temperature (SST) and productivity records for the interval from 2 to 3 million years ago at DSDP Site 607 (41ºN, 32ºW); located in the North Atlantic Ocean, the region most significantly impacted by the Plio-Pleistocene transition. Our Site 607 data completes a transect of sites from the equator to 69º N in the Atlantic Ocean, including ODP 662, DSDP 607, ODP 982, and ODP 907. Our data show an overall cooling trend with the mid to high latitude regions (>40ºN) cooling faster then the low latitude regions (<40º N) at rates ranging from 0.6ºC/Myr to 2.2ºC/Myr. On orbital time scales, our mid to low latitude SST records like most climate time series that span the Plio-Pleistocene transition, show an increase in variance at ~2.7 Ma in association with the intensification of northern hemisphere glaciation. In contrast, our high latitude SST records show large amplitude variations (4 to 8ºC) even before ~2.7 Ma. Our data indicate widespread cooling, but also highlight notably different regional temperature responses to this global climatic transition. The pattern of C37 Total (productivity) variations is different between high (>57ºN) and mid to low (<45ºN) latitude regions in the Atlantic Ocean. Our data indicates that high latitude regions experienced time transgressive productivity crashes, occurring at 3.5 Ma at Site 907 and at 2.5 Ma at Site 982. In contrast, an increase in productivity occurred in the mid to low latitudes at ~2.7 Ma. This broad change in Atlantic productivity pattern suggests that a significant redistribution of nutrients was associated with the Plio-Plesitocene transition.