4:15 PM - 4:30 PM
[MIS10-32] Dating of stalagmites from Kyusendo cave, Kumamoto, using U–Th and radiocarbon dating methods
Keywords:stalagmite, U-Th dating, radiocarbon dating
In this study, stalagmites KST4, 5 and 6 from Kyusendo cave in Kumamoto, Japan were used because U concentrations of the stalagmites were suitable for U–Th dating. Three stalagmites were dated using U–Th methods for the first time in Japan as follows; 41 ka–9 ka of KST4, 25 ka–1.3 ka of KST5, 45 ka–25 ka of KST6. 14C age of stalagmites and drip water were also measured. From drip water, modern DCF was determined. 14C age were corrected with modern DCF and the corrected age of the modern stalagmite showed good agreement with U–Th age.
Availability of U–Th dating methods in Japan would contribute to the activation of Japanese stalagmite research. In the future, by measuring stable isotopes of stalagmites, the paleoclimate system in the area of East Asian summer monsoon could be revealed. In addition, we are going to analyze trace elements and DCF fluctuation and examine the availability as environmental proxy.
Genty, D., Massault, M., Baker, A., Vokal, B., & Proctor, C. J. (1999, September). Reconstitution of bomb 14C time history recorded in four modern stalagmites by AMS measurements: Importance for carbon transfer dynamics. In 8th International Conference on AMS (pp. 6-10).
Genty, D., Baker, A., Massault, M., Proctor, C., Gilmour, M., Pons-Branchu, E., & Hamelin, B. (2001). Dead carbon in stalagmites: carbonate bedrock paleodissolution vs. ageing of soil organic matter. Implications for 13 C variations in speleothems. Geochimica et Cosmochimica Acta, 65(20), 3443-3457.