Holocene and Pleistocene glacial palaeoceanography off southeastern Australia, based on foraminifers and nannofossils in Vema cored hole V18–222∗

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Abstract
Sea‐surface temperature trends in planktonic foraminifers, isotopic and population abundance trends in benthic foraminifers, and abundance trends in calcareous nannofossils of V18–222 (38°34'S, 140°37'E, southeast Australia: 1904 m water depth) reveal an interglacial interval (oxygen isotope stage 1) distinctly different from underlying glacial intervals (isotope stages 10 and 12). During the glacial times mean sea‐surface temperatures (FI‐2 planktonic foraminiferal transfer function) ranged between 12°C and 9°C, indicating the close proximity of the Subtropical Convergence Zone. The cooler waters were unfavourable for the existence of the nannofossil Florisphaera profunda, while cooler water flora like Coccolithus pelagicus and Gephyrocapsa caribbeanica flourished. Absence of tropical and subtropical nannoflora suggest that the Leeuwin Current did not flow across the area at this time. High surface productivity, associated with strong upwelling during this time is indicated by Bulimina aculeata‐dominated benthic foraminiferal populations, and by Uvigerina spp. depleted in δ13C. At depth it is likely that the core site was immersed in Circumpolar Deep Water. In contrast, during interglacial stage 1 and the end of stage 2 deglaciation, mean sea‐surface temperatures at the site ranged between 14°C and 18°C, similar to modern temperatures. High summer sea‐surface palaeotemperatures indicate that the Subtropical Convergence was positioned well south of the site during the last ∼14 000 years. The persistent presence of a warm‐water nannoflora indicates that the Leeuwin Current flowed over the area throughout warm extremes in climate through the last ∼14 000 years. Anomalously low winter sea‐surface palaeotemperatures during the same time, however, coupled with the persistent presence of Florisphaera profunda in low abundance, indicate a persistence of mild upwelling activity in the area, similar to that which exists today, since ca 14 ka. Stable deep‐water conditions during the interglacial are indicated by benthic foraminiferal population trends with a fauna dominated by Bulimina striata and uniform, but relatively high, δ13C signals in Uvigerina spp., with the site immersed in a mixture of Antarctic Intermediate Water and Antarctic Circumpolar Water.