[M-IS14] Paleoclimatology and paleoceanography

[MIS14-08] Covariation of terrestrial temperature and precipitation during the last 80 kyr revealed from oxygen and carbonate clumped isotopes of a stalagmite from Mie Prefecture.

*Hirokazu Kato¹, Taiki Mori², Ryoko Senda³, Akihiro Kano⁴ (1.Faculty of Education and Human Sciences, Teikyo University of Science, 2.Chuo Kaihatsu Corporation, 3.Graduate School of Social and Cultural Studies, Kyushu University, 4.Graduate School of Science, The University of Tokyo)

Keywords:Stalagmite, Paleo climate, Carbonate clumped isotopes, East Asian Monsoon

The oxygen isotopic composition of stalagmite calcite (δ¹⁸O_C) is controlled by two main factors; the temperature of calcite formation and the oxygen isotopic composition of cave drip water (δ¹⁸O_W) derived from meteoric water. Stalagmite δ¹⁸O_C is therefore an important source of information for terrestrial paleoclimates. It is however impossible to determine their relative importance by measuring only stalagmite δ¹⁸O_C. Carbonate dual clumped isotopes (Δ₄₇ and Δ₄₈) thermometry (Guo and Zhou, 2019; Guo, 2020) is a way to reconstruct the terrestrial temperature change independently. The principle of the method is based on temperature dependency of abundance anomaly of ¹³C-¹⁸O bond (Δ₄₇) relative to the stochastic abundance. It is however Δ₄₇ values of stalagmites were affected by disequilibrium effects induced by CO₂ degassing from the parent water. The stalagmite Δ₄₇ values can be corrected to the equilibrium values using Δ₄₈ values together.
We analyzed Δ₄₇ and Δ₄₈ values from over 60 layers of KA03 stalagmite from Kiriana Cave, Mie Prefecture, covering two separate time intervals (5.2–13.2 and 22.6–83.4 ka: Mori et al., 2018) to reconstruct terrestrial temperature and meteoric δ¹⁸O_W records. The temperature history revealed from the dual clumped isotopes of KA03 exhibit cyclic cooling corresponding to Heinrich stadials (H2–7) in the latest Pleistocene, cooling to the last glacial maximum and warming in the Holocene.
We also reconstructed past meteoric δ¹⁸O_W by subtracting the temperature effect from stalagmite δ¹⁸O_C. Over centennial timescales, meteoric δ¹⁸O_W was more negative during colder periods and less negative in warmer periods. The correlation between temperature and meteoric δ¹⁸O_W was already reported from other regions of Japan (Kato et al., 2021; 2023) and indicate the coevolution of terrestrial paleotemperature and paleoprecipitation; increased precipitation brought by EASM has likely increased the average meteoric δ¹⁸O_W in warmer periods, whereas increased precipitation brought by EAWM has decreased the averaged meteoric δ¹⁸O_W in colder periods.

References
Guo, W. & Zhou, C. 2019. GCA 267, 196–226.
Guo, W. 2020. GCA 268, 230–257.
Kato et al., 2021. QSR 253, 106746.
Kato et al., 2023. Chem. Geol. 622, 121390.
Mori et al., 2018. QSR 192, 57–58.