Variations in sea surface hydrology in the southern Makassar Strait over the past 26 kyr

Abstract

We present centennial-scale records of sea surface temperature and oxygen isotopes in a sediment core from Mandar Bay, offshore Sulawesi in the southern Makassar Strait, which provide new insights into the variability of Indonesian climate over the past 26 kyr. The age model for the core is constrained by 17 AMS radiocarbon ages, with a surface ocean reservoir age correction based on paired wood and foraminiferal samples. Small Holocene reservoir ages of 105 180 years point to intense surface ocean atmosphere interchange linked to increased monsoonal precipitation, whereas Last Glacial Maximum and deglacial reservoir ages are significantly higher. Mg/Ca derived sea surface temperature reconstructions based on Globigerinoides ruber (s. s., white) exhibit an extended plateau during the Antarctic Cold Reversal, suggesting an atmospheric connection to high-latitude Southern Hemisphere climate and a seasonal bias on G. ruber. This is in agreement with southern hemisphere sites along the track of the Indonesian Throughflow and in contrast to Northern Hemisphere records from the South China Sea, Sulu Sea and Western Pacific (off Mindanao), which exhibit warming during the Bolling-Allerod. Ice-volume corrected delta O-18 seawater delta O-18(sw) increased during Heinrich Stadial 1 and the Younger Dryas, whereas the Bolling-Allerod is characterized by low delta O-18(sw). We attribute delta O-18(sw) variability in the southern Makassar Strait during the Last Glacial Maximum and glacial termination to changes in provenance and seasonality of precipitation rather than to variability in the amount of local precipitation and runoff. (C) 2016 Elsevier Ltd. All rights reserved.