A high-resolution, annual layer-counted and 230Th-dated multi-proxy record is constructed from a stalagmite in Hulu Cave, China. These proxies, including δ18O, annual layer thickness (ALT), gray level (GL) and Sr/Ca, cover a time span of ~3000yr from 21 to 24ka. The physical proxies (ALT and GL) and the geochemical index (Sr/Ca), all primarily reflecting karst hydrological processes, vary in concert and their coherence is supported by wavelet analyses. Variations in the δ18O data agree with fluctuations in the ALT and Sr/Ca records on multi-decadal to centennial scales, suggesting that the Hulu δ18O signal is strongly associated with varying local rainfall amounts on short timescales. A monsoon failure event at ~22.2ka correlates with a decrease in tropical rainfall, a reduction in global CH4 and an ice-rafted event in the North Atlantic. This correlation highlights roles of the Asian monsoon and tropical hydrological cycle in modulating global CH4, because the high-latitude emission was inhibited during the Last Glacial Maximum (LGM). Spectral analysis of the δ18O record displays peaks at periodicities of 139, 59, 53, 43, 30, 23 and 19-15yr. The absence of typical centennial solar cycles may be related to muted changes in ocean circulation during the LGM.
Bibliographical noteFunding Information:
We gratefully acknowledge Prof. Christoph Spötl, Prof. Matthew Lachniet and an anonymous reviewer for their thorough reviews, constructive suggestions and comments, and editorial corrections, which greatly improved the overall quality of the manuscript. This work was supported by grants of the National Natural Science Foundation of China (nos. 41130210 , 41372174 and 41172314 ).
© 2015 University of Washington.
- East Asian summer monsoon
- Hulu Cave
- Last Glacial Maximum
- Monsoon rainfall