Late Quaternary ostracod and planktonic foraminiferal dissolution signals from the eastern Tasman Sea — palaeoenvironmental implications

A recently developed ostracod corrosion index is compared (and contrasted) with planktonic foraminiferal fragmentation in latest Quaternary carbonate sediments from the Challenger Plateau, eastern Tasman Sea. Although assemblage data for ostracodal corrosion and planktonic foraminiferal fragmentation are similar (accepting a foraminiferal peak which anticipates the ostracod signal by about 8 kyr in isotopic stage 3, and a second peak which lags that for Ostracoda in isotopic stage 1 by an equivalent amount), plots of carapace corrosion of some ostracod genera show no such relationship. The planktonic foraminiferal fragmentation in core GR 54 during the last three isotopic stages duplicates the δ18O signal, suggesting regional surface-water temperature changes had a significant influence on that signal. In contrast, the corrosion index for representatives of the ostracod genus Krithe accurately tracks the δ13C for those 3 isotopic stages. We conclude that the intensity of degradation of those ostracod valves is an accurate reflection of productivity fluctuations in surface-water through time.