Stalagmite Oxygen Isotope Studies Guizhou Bamboo Stroll Pyeongdong Since Deglaciation

As a fast and sensitive physical system, the Asian monsoon (AM) is an active component of atmospheric circulation and plays a significant role in the global hydro logic and energy cycles. Stalagmites from the AM region are ideal terrestrial archives in that they can reflect changes in the AM strength, so they are uniquely positioned in paleo-environmental studies. In this thesis, two stalagmites were collected from Zhuliuping cave,where is influenced by southeast and also southwest Asia summer monsoons. A time series of Asian summer monsoon variability from14.0to4.6ka BP is reconstructed based on10high-precision U/Th dates and984oxygen isotope data.During the14.0～4.6ka, the long-term trend of the Zhuliuping cave818O record correlates the summer insolation at33°N latitude. The fact that the good replication of δ18O signal between Zhuliuping Cave and others in the AM area during the contemporaneous growth periods indicates that the δ18O signal in these caves are controlled by a common climate factor and the δ18O can reveal the AM climate changes on centennial-decadal scales.The δ18O curves show clearly the millennial-centennial climate events similar to the North Atlantic region, in which include YD event, Aller(?)d and8.2ka event in the Holocene, which indicates there is a striking relation of forcing and response between the AM and polar region climate. Moreover, the high-resolution climate event sequences of the stalagmite reflect the process and transition features of these events. Aller(?)d present a trend of cold and dry to warm and wet as a whole. Climate changes of the early periods in YD event is more shaper than that the late YD event and the YD event comprise more than ten cold/warm oscillations with an amplitude of over2%o.All these decadal-centennial climate information has a corresponding relation to Greenland ice core record.By comparing high-resolution δ18O records of stalagmite from Zhuliuping with that from Qunf cave(Oman), the Dongge cave(Guizhou), and the Shanbao cave(Hubei), we find that the long-term trends of these stalagmite records agree well with each other, suggesting changes of Indian and East Asian summer monsoon are not out phase at millennial-centennial scale. Our records provide direct evidences that there is a more precise correlation between AM and Greenland climate on centennial scales during the early Holocene, which indicates that early Holocene Asian Monsoon intensity was controlled by glacial boundary forcing. However, the broad decline in Asian monsoon intensity during the Middle-Holocene was directly controlled by the orbital-induced lowering of summer insolation affecting gradual southward migration of Inter-tropical Convergence Zone.Spectral analysis on the stalagmite δ18O records display many strong periodicities, such as833,500,420,250,185,93,70,24,22and21years, which have the distinctive features as sunspot activity. These periodicities reveal that the solar activity is a dominating factor in the evolution of the Asian climatic change in centennial-decadal time scales.