Sea surface paleoproductivity reconstruction based on foraminiferal accumulation rate in the western Savu Strait since the Last Glacial Maximum (∼23 ka BP)

Despite its importance, sea surface paleoproductivity of the western Savu Strait is not well studied. Results from previous study at the nearby Southwest Sumba and Sumba Strait might not be applicable due to the oceanographic difference. Foraminiferal proxies from gravity core ST10 were applied to generate sea surface paleoproductivity and thermocline depth reconstruction. Foraminiferal Accumulation Rate and Benthic Foraminiferal Accumulation Rate were used as paleoproductivity proxies while the thermocline dwellers' relative abundance was applied as the thermocline depth proxy. This study suggested paleoproductivity increase during the Last Glacial Maximum (LGM)-similar to 16 ka BP and Holocene (after similar to 11.65 ka BP) in the western Savu Strait. Thermocline depth was relatively shallower during the LGM-Last Deglaciation and became deeper afterwards. Paleoproductivity increase at LGM-similar to 16 ka BP was caused by the Australian-Indonesian winter monsoon (AIWM)-like condition, characterised by intense coastal upwelling while the Holocene paleoproductivity increase was related to the abrupt rainfall increase which enhanced terrestrial/riverine input. Thermocline depth variability in the western Savu Strait is in-phase with thermocline depth variability in the Java upwelling region, characterised by a shallower thermocline during the LGM-Last Deglaciation (before similar to 11.65 ka BP) and a deeper thermocline during the Holocene (after similar to 11.65 ka BP). This thermocline depth shifting indicates a strong Australian-Indonesian Monsoon (AIM) influence on the paleoceanography of the western Savu Strait since LGM.