MOVEMENT OF HYDROLOGICAL FRONTS AND WIDESPREAD EROSIONAL EVENTS IN THE SOUTHWESTERN TASMAN SEA DURING THE LATE QUATERNARY

The planktonic foraminiferal palaeotemperatures and oxygen isotopes, r adiocarbon dates and calcareous nannoplankton biostratigraphy of six d eep-sea cores in the southwestern Tasman Sea are presented, along with the nannoplankton biostratigraphy of the tops of 23 other cores in th e region. A complex history of deposition and erosion is indicated, wi th development of hiatuses at 10 ka, and widespread absence of sedimen ts younger than 73 ka. The history of movement of the major hydrologic al fronts over the areas west to southwest of Tasmania has been deduce d from palaeotemperature records of the undisturbed core segments. Dur ing the Last Glacial Maximum, the Subtropical Convergence was position ed north of 42 degrees S, 145 degrees E. During the subsequent deglaci ation and Holocene the front rapidly moved southward, with its souther n limits established south of 47 degrees S. Presently the northern lim it of the Polar Front south of Tasmania is positioned south of similar to 50 degrees S, and palaeotemperatures and the absence of silica-ric h sediments in all cores north of there, suggests that the front has b een south of there during the past 500 000 years.