Planktic foraminifera-based sea-surface temperature record in the Tasman Sea and history of the Subtropical Front around New Zealand, over the last one million years

Planktic foraminiferal assemblages in a composite section from two cores (MD06-2989/2986) off the west coast of New Zealand's South Island (42-43.5 degrees S) provide a 1 myr (MIS 31-1) sea-surface temperature (SST) record (similar to 3-4 kyr resolution) in the Tasman Sea. A significant overall faunal change occurred near the end of the midPleistocene Climate Transition (MPT) at similar to 600 ka (MIS 15). Mean annual SSTs were estimated using the Artificial Neural Network (ANN) method. Glacial-interglacial (G-I) cycles in the MPT had similar to 9 degrees C SST range, whereas in the post-MPT SST range was similar to 6-7 degrees C. The SST and faunal changes imply that the Subtropical Front (STF) migrated similar to 6 degrees in latitude to lie just north of the sites in MPT glacials (MIS 28-16), but only migrated 3-5 degrees north in postMPT glacials. These G-I latitudinal migrations of the STF west of New Zealand contrast with the situation east of New Zealand, where migrations of both the STF and Subantarctic Front were prevented by the Chatham Rise and Campbell Plateau. Subtropical Water is inferred to have only flowed around the south of New Zealand (as it does today) during MIS 11 and the Late Pleistocene-Holocene (MIS 5-1). (C) 2011 Elsevier By. All rights reserved.