TY - JOUR
T1 - Last glacial temperature reconstructions using coupled isotopic analyses of fossil snails and stalagmites from archaeological caves in Okinawa, Japan
AU - Asami, Ryuji
AU - Hondo, Rikuto
AU - Uemura, Ryu
AU - Fujita, Masaki
AU - Yamasaki, Shinji
AU - Shen, Chuan Chou
AU - Wu, Chung Che
AU - Jiang, Xiuyang
AU - Takayanagi, Hideko
AU - Shinjo, Ryuichi
AU - Kano, Akihiro
AU - Iryu, Yasufumi
N1 - Funding Information:
We are grateful to Dr. J. Zinke (Editor) and two reviewers (Dr. O. Kwiecien and an anonymous reviewer) for useful suggestions on our manuscript. We thank Nanto Co. Ltd. for permission to collect samples from the caves, and S. Oooka for assistance with fieldwork. We also thank M. Chinen, H. Miyata, Y. Akamine, K. Ohmine, and Y. Uechi of the University of the Ryukyus, and J.-P. Chen of the National Taiwan University, for assistance with the experiments. This research was supported by the Japan Society for the Promotion of Science (JSPS), KAKENHI (Grants 26550012, 26707028, and 18K18522 to R.A. and 15H01729 and 20H00628 to R.U.), Marie Curie Fellowships by European Commission (Grant 891710 to C.-C. W.), and Frontier Research in Duo (FRiD) of Tohoku University to Y.I. U–Th dating at HISPEC was supported by grants from the Science Vanguard Research Program of the Ministry of Science and Technology (MOST; Grant 109-2123-M-002-001), Higher Education Sprout Project of the Ministry of Education (Grant 109L901001), and National Taiwan University (Grant 110L8907).
Publisher Copyright:
© 2021, The Author(s).
PY - 2021/12
Y1 - 2021/12
N2 - We applied a new geoarchaeological method with two carbonate archives, which are fossil snails from Sakitari Cave and stalagmites from Gyokusen Cave, on Okinawa Island, Japan, to reconstruct surface air temperature changes over the northwestern Pacific since the last glacial period. Oxygen isotope ratios (δ18O) of modern and fossil freshwater snail shells were determined to infer seasonal temperature variations. The observational and analytical data confirm that δ18O values of fluid inclusion waters in the stalagmite can be regarded as those of spring waters at the sites where snails lived. Our results indicate that the annual mean, summer, and winter air temperatures were lower by 6–7 °C at ca. 23 thousand years ago (ka) and 4–5 °C at ca. 16–13 ka than those of the present day. Our reconstruction implies that surface air cooling was possibly two times greater than that of seawater around the Ryukyu Islands during the Last Glacial Maximum, which potentially enhanced the development of the East Asian summer monsoon during the last deglaciation. Considering the potential uncertainties in the temperature estimations, the climatic interpretations of this study are not necessarily definitive due to the limited number of samples. Nevertheless, our new geoarchaeological approach using coupled δ18O determinations of fossil snails and stalagmite fluid inclusion waters will be useful for reconstructing snapshots of seasonally resolved time series of air temperatures during the Quaternary.
AB - We applied a new geoarchaeological method with two carbonate archives, which are fossil snails from Sakitari Cave and stalagmites from Gyokusen Cave, on Okinawa Island, Japan, to reconstruct surface air temperature changes over the northwestern Pacific since the last glacial period. Oxygen isotope ratios (δ18O) of modern and fossil freshwater snail shells were determined to infer seasonal temperature variations. The observational and analytical data confirm that δ18O values of fluid inclusion waters in the stalagmite can be regarded as those of spring waters at the sites where snails lived. Our results indicate that the annual mean, summer, and winter air temperatures were lower by 6–7 °C at ca. 23 thousand years ago (ka) and 4–5 °C at ca. 16–13 ka than those of the present day. Our reconstruction implies that surface air cooling was possibly two times greater than that of seawater around the Ryukyu Islands during the Last Glacial Maximum, which potentially enhanced the development of the East Asian summer monsoon during the last deglaciation. Considering the potential uncertainties in the temperature estimations, the climatic interpretations of this study are not necessarily definitive due to the limited number of samples. Nevertheless, our new geoarchaeological approach using coupled δ18O determinations of fossil snails and stalagmite fluid inclusion waters will be useful for reconstructing snapshots of seasonally resolved time series of air temperatures during the Quaternary.
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U2 - 10.1038/s41598-021-01484-z
DO - 10.1038/s41598-021-01484-z
M3 - Article
C2 - 34754040
AN - SCOPUS:85118664614
VL - 11
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 21922
ER -