Calcite saturation, foraminiferal test mass, and Mg/Ca-based temperatures dissolution corrected using XDX-A 150 ka record from the western Indian Ocean

A record of deep-sea calcite saturation (Delta[CO32-]), derived from X-ray computed tomography-based foraminifer dissolution index, XDX, was constructed for the past 150 ka for a core from the deep (4157 m) tropical western Indian Ocean. G. sacculifer and N. dutertrei recorded a similar dissolution history, consistent with the process of calcite compensation. Peaks in calcite saturation (similar to 15 mmol/kg higher than the present-day value) occurred during deglaciations and early in MIS 3. Dissolution maxima coincided with transitions to colder stages. The mass record of G. sacculifer better indicated preservation than did that of N. dutertrei or G. ruber. Dissolution-corrected Mg/Ca-derived SST records, like other SST records from marginal Indian Ocean sites, showed coolest temperatures of the last 150 ka in early MIS 3, when mixed layer temperatures were similar to 4 degrees C lower than present SST. Temperatures recorded by N. dutertrei showed the thermocline to be similar to 4 degrees C colder in MIS 3 compared to the Holocene (8 ka B.P.).