[U-03] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

[U03-04] Multidecadal reconstruction of mid-Holocene climate of Western Pacific based on the stalagmite fluid inclusion isotopes

★Invited Papers

*Syed Azharuddin¹、Kanako Omine²、Kosuke Masaka²、Ryuji Asami³、Mahjoor Ahmad Lone⁴、Yu-Chen Chou⁴、Chuan-Chou Shen⁴、Ryu Uemura¹ (1.Graduate School of Environmental Studies, Nagoya University, Japan、2.Faculty of Science, University of the Ryukyus, Japan、3.Graduate School of Science, Tohoku University, Japan、4.High-precision mass spectrometry and environment change laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taiwan ROC)

キーワード：Stalagmite, Stable Isotopes, Fluid Inclusions, Holocene

The oxygen isotopes in speleothem carbonate (δ¹⁸O_ca) have been widely used to study the past changes in monsoonal precipitation, whereas the role of calcite formation temperature remains elusive. With recent analytical advancements, the δ¹⁸O_ca coupled with oxygen and hydrogen isotopes in speleothem fluid inclusions (δ¹⁸O_fi and δD_fi) offer great potential for reconstructing past air temperatures. Here we present a record of δ¹⁸O_fi and δD_fi analyzed in HSN1 stalagmite from Hoshino Cave at Minami-Daito Island situated in Okinawa prefecture around the Northwestern Pacific. A robust age model was established with precise U-Th ages between 6.0 to 7.4 thousand years before the present (where the present is 1950 AD). The high-growth rate of HSN1 stalagmite (180 μm/yr) enabled us to study the past changes in precipitation and temperature with a high temporal resolution. The reconstructed air temperature shows strong multidecadal variability during the mid-Holocene. We compared our results with regional and global paleo-proxy records to identify the different forcings and teleconnections. Multiproxy data show a 65-year cycle related to the variability in the Atlantic Multidecadal Oscillation (AMO) and the multidecadal AMO-Western Pacific teleconnection.