Stalagmite-inferred variability of the Asian summer monsoon during the penultimate glacial–interglacial period
- 1Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Geographical Sciences, Southwest University, Chongqing 400715, China
- 2State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS, Xi'an 710075, China
- 3High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan, ROC
- 4College of Geographical Science, Fujian Normal University, Fuzhou 350007, China
- 5Department of Earth Sciences, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
- 6Research Center for Environmental Changes, Academia Sinica, Taipei 11529, Taiwan, ROC
Abstract. The orbital-timescale dynamics of the Quaternary Asian summer monsoons (ASM) are frequently attributed to precession-dominated northern hemispheric summer insolation. However, this long-term continuous ASM variability is inferred primarily from oxygen isotope records of stalagmites, mainly from Sanbao cave in mainland China, and may not provide a comprehensive picture of ASM evolution. A new spliced stalagmite oxygen isotope record from Yangkou cave tracks summer monsoon precipitation variation from 124 to 206 thousand years ago in Chongqing, southwest China. Our Yangkou record supports that the evolution of ASM was dominated by the North Hemisphere solar insolation on orbital timescales. When superimposed on the Sanbao record, the precipitation time series referred from Yangkou cave stalagmites supports the strong ASM periods at marine isotope stages (MIS) 6.3, 6.5, and 7.1 and weak ASM intervals at MIS 6.2, 6.4, and 7.0. This consistency confirms that ASM events affected most of mainland China. Except for the solar insolation forcing, the large amplitude of minimum δ18O values in Yangkou record during glacial period, such as MIS 6.5, could stem from the enhanced prevailing Pacific trade wind and/or continental shelf exposure in the Indo–Pacific warm pool.