A high-resolution stalagmite oxygen isotope record from Tianmen Cave, located in the south central Tibetan Plateau, characterizes detailed climatic variations between 8.7 and 4.3ka BP on centennial and decadal time scales, with a temporal resolution of 3 to 7 years. The Tianmen record is in good agreement with speleothem records from Asian monsoon regions (i.e., Dongge Cave, Dykoski et al., 2005; Wang et al., 2005; Qunf Cave, Fleitmann et al., 2003), upwelling records from the Arabian Sea (Gupta et al., 2003, 2005) and peat bog records from southeast Tibetan Plateau (Hong et al., 2003), indicating that the Indian summer monsoon (ISM) gradually weakened as Northern Hemisphere summer insolation declined during the early-mid Holocene and that ISM intensity, rather than temperature, dominates the precipitation δ 18O on centennial to decadal time scales in the southern TP. On centennial to decadal time scales, the detrended Tianmen record correlates well with the Greenland ice core record, further confirming the mechanistic connection between the ISM and high northern latitude temperature changes. Meanwhile, the Tianmen record bears significant solar activity cycles, suggesting that the solar output changes may affect the variability of the ISM and likely the position of the Intertropical Convergence Zone (ITCZ) as well. Moreover, due to joint effects of changes in monsoon precipitation, moisture source and temperature, the Tianmen δ 18O record shows much larger amplitude changes than speleothem δ 18O records from low-elevation Asian Monsoon regions, which is similar to the previously reported Marine Isotope Stage (MIS) 5 record (Cai et al., 2010), suggesting heightened sensitivity of precipitation isotope composition to climate changes over the high-elevation regions and further demonstrating that the stable isotope lapse rate may change under different climatic conditions.
Bibliographical noteFunding Information:
We thank two anonymous reviewers for helpful comments. This work was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences ( KZCX2-EW-QN109 ), the West Light Foundation of the Chinese Academy of Sciences , the MOST special fund for the State Key Laboratory of Loess and Quaternary Geology , the United States National Science Foundation (Grant EAR-0908792 ); and the Gary Comer Science and Education Foundation Grant CC8 .
- Indian summer monsoon
- Lapse rate
- Oxygen isotope
- Tibetan Plateau