Movement of hydrological fronts and widespread erosional events in the southwestern Tasman sea during the Late Quaternary*

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The planktonic foraminiferal palaeotemperatures and oxygen isotopes, radiocarbon dates and calcareous nanno‐plankton biostratigraphy of six deep‐sea cores in the southwestern Tasman Sea are presented, along with the nannoplankton biostratigraphy of the tops of 23 other cores in the region. A complex history of deposition and erosion is indicated, with development of hiatuses at 10 ka, and widespread absence of sediments younger than 73 ka. The history of movement of the major hydrological fronts over the areas west to southwest of Tasmania has been deduced from palaeotemperature records of the undisturbed core segments. During the Last Glacial Maximum, the Subtropical Convergence was positioned north of 42°S, 145°E. During the subsequent deglaciation and Holocene the front rapidly moved southward, with its southern limits established south of 47°S. Presently the northern limit of the Polar Front south of Tasmania is positioned south of ∼50cS, and palaeotemperatures and the absence of silica‐rich sediments in all cores north of there, suggests that the front has been south of there during the past 500 000 years.