Orbital‐ to millennial‐scale variation of the speleothem δ 18 O record during Marine Isotope Stages 5 to 3 on the southeast Chinese Loess Plateau and its climatic and environmental implications

• Published in: Journal of Quaternary Science
• Main Authors: CAI, YANJUN, CHENG, HAI, CHENG, XING, SHI, ZHENGGUO, LU, YANBIN, MA, LE, PÉREZ‐MEJÍAS, CARLOS, ZHANG, HAIWEI, WEI, YINGYING, XUE, GANG, LI, HANYING, HE, MEI, WANG, TING, EDWARDS, R. LAWRENCE, AN, ZHISHENG
• Other Authors: National Natural Science Foundation of China, Chinese Academy of Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Pacific; North Atlantic; Sea ice
• Online Access: http://dx.doi.org/10.1002/jqs.3489; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3489; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jqs.3489

ABSTRACT The Chinese Loess Plateau (CLP) is located in northern China, a region climatically dominated by the East Asian monsoon. Speleothem records from this region are crucial to fully understand the variability of the East Asian summer monsoon (EASM) and reconcile the disparity seen between loess records and speleothem δ 18 O records for the EASM. Here, we present an absolutely dated stalagmite isotope record spanning most of Marine Isotope Stage (MIS) 5 to MIS 3 from Xiaotian Cave, southeast CLP. The Xiaotian speleothem δ 18 O record is dominated by precessional variations and punctuated by notable millennial‐scale oscillations; in particular, the δ 18 O values in MIS 5e, 5c and 5a were in the same range, consistent with other speleothem δ 18 O records from the EASM region within quoted errors, verifying the difference between speleothem δ 18 O and loess records (e.g. magnetic susceptibility) and the proposition that those two archives may record different aspects of the EASM changes. The similar values in MIS 5e, 5c and 5a observed from the speleothem δ 18 O records in EASM regions, incompatible with the relatively higher North Hemisphere Summer Insolation (NHSI) during MIS 5e, were probably caused by an equivalent or even increased contribution of 18 O‐enriched moisture from the South China Sea and North Pacific, implying that an El Niño‐like state existed during MIS 5e. The Xiaotian δ 18 O values increased abruptly at ~121.7 thousand years (kyr) before the present ( bp , present refers to ad 1950), consistent with the trend seen in previously reported Chinese speleothem δ 18 O records, indicating an abrupt regime shift in atmospheric circulations or hydroclimate conditions in the Asian monsoon systems. It cannot be definitely ruled out that an increase in sea ice extent in the northern North Atlantic, responding to a decrease of NHSI, reached a threshold to have led to abrupt changes in the Asian summer monsoon (ASM) through rapid shifts in the position of circulation of the westerlies and/or in the ...