Last glacial climate oscillations and sudden environmental changes investigated in stalagmites from southwest Sulawesi, western Pacific

Authors: EZGİ ÜNAL İMER, İBRAHİM TONGUÇ UYSAL, EMMA ST PIERRE, JIAN XIN ZHAO, JAMES SHULMEISTER

Abstract: We investigated two stalagmites from the Saripa Cave and Bumi Cave in southern Sulawesi, Indonesia, using high-precision U-series dating and high-resolution trace element and C-O-Sr isotope analysis. The growth record (from 10.4 ± 0.1 ka to 77.4 ± 0.9 ka) of the Saripa Cave stalagmite (SR04-ST3) is fragmented with two major (at the top: 10.4-11.6 ka and middle: 43.8-44.7 ka sections of the stalagmite) and some short (middle and bottom sections) growth phases, interrupted by long-lasting growth hiatuses. Both the timing of the growth phases and the δ¹⁸O values for different growth phases are correlated with those of cold/dry (~22 ka and 43.8-44.7 ka) and wet/warm periods (e.g., Greenland Interstadials 12, 14, and 21) in the northern hemisphere speleothem records, displaying both anti-phase and in-phase relationships with the northern hemisphere records. This observation is unique in the Western Pacific tropical region, mostly likely because the Saripa Cave is located within the region of the latitudinally migrating Intertropical Convergence Zone (ITCZ), whereby the rainfall seasons may have changed through time depending on the mean latitude of the ITCZ. The Saripa Cave stalagmite contains textural laminae, which are here interpreted as a record of rapid environmental changes, possibly caused by volcanic eruptions at around 22.55 ka and 44.73 ka BP. The Bumi Cave record (stalagmite BC-09-3-C), on the other hand, presents very little variation in stable isotope and trace element compositions between 26.8 ka and 18.5 ka and does not seem to be influenced by any possible volcanic activity. More detailed future studies investigating millimeter- to submillimeter-scale geochemical time-series constrained by accurate ages in speleothems can be useful in unfolding the effects of eruptions and provide parallel records of climate and sudden environmental changes.

Keywords: Stalagmite, U-series dating, isotope geochemistry, trace elements, past climate

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