Validation of glacial-interglacial rainfall variations in southwest Sulawesi using Mg/Ca and δ18O in speleothems

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Alena K Kimbrough, Michael Gagan, Gavin Dunbar, Wahyoe Hantoro, Chuan-Chou Shen, Hsun-Ming Hu, Hai Cheng, Larry Edwards, Hamdi Rifai, Bambang W Suwargadi


Speleothem δ18O is widely used as a proxy for rainfall amount in the tropics on glacial-interglacial to interannual scales. However, uncertainties in the interpretation of this renowned proxy pose a vexing problem in tropical paleoclimatology. Here, we present paired measurements of Mg/Ca and δ18O for multiple stalagmites from southwest Sulawesi, Indonesia, that that confirm changes in rainfall amount across ice age terminations. Collectively, the stalagmites span two glacial-interglacial transitions from 380 to 330 ky BP and 230 to 170 ky BP. Mg/Ca in our slow-growing stalagmites is affected by karst infiltration rates and prior calcite precipitation, making it a good proxy for changes in local rainfall. When paired, Mg/Ca and δ18O corroborate prominent shifts from drier glacials to wetter interglacials in the core of the Australasian monsoon domain. Deviations between the two proxies may reveal concurrent changes in rainfall amount and moisture-transport pathways indicative of regional monsoon circulation.



Atmospheric Sciences, Climate, Earth Sciences, Geochemistry, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Speleology


Tropical speleothems, Mg/Ca, δ18O, prior calcite precipitation, Indonesia, glacial-interglacial paleoclimates, Mg/Ca, δ18O, prior calcite precipitation, Indonesia, Glacial-Interglacial, paleoclimate


Published: 2022-06-17 11:32

Last Updated: 2022-06-17 15:32


CC BY Attribution 4.0 International

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Conflict of interest statement:
The authors declare no competing interests.

Data Availability (Reason not available):
Please email Alena Kimbrough for the data spreadsheets mentioned in the manuscript and Supplementary Information.

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