The Last Glaciation In Southwest Guizhou Stalagmite Records High-resolution Asian Monsoon Changes

As a fast and sensitive physical system, Asian monsoon (AM) is well known for its prominently seasonal contrast in precipitation and surface wind, and also provides a link for ocean-atmosphere-ice interactions and northern/southern climates. It can transmit abrupt climate signals from low-and high-latitudes/southern-northern hemispheres via westerlies and trans-equator circulations. Cave deposits from the AM region are ideal terrestrial archives in that they can reflect changes in the AM strength and its associated isotopic composition, so they are uniquely positioned in paleo-environmental studies. In this thesis, three stalagmites were collected from WuLu cave, where is influenced by an interplay of southeast and southwest Asian monsoons. A time series of Asian summer monsoon variability from 39.2 to 15.3 ka BP is reconstructed on about 24 high-precision U/Th dates and 1,886 oxygen data.The fact that the fairly good replication ofδ18O signal between Wulu Cave and other stalagmites in the Asian monsoon area during the contemporaneous growth periods indicates that theδ18O signal in the two caves are controlled by the common climate factor and that theδ18O signal can reveal the Asina monsoon climate changes on centennial-millennial scales.Through the oxygen isotope characteristics of stalagmites, combined with the annual-layer counting method, caliabated the duration of H3 accurately. It is close to the record of Ca2+ of GISP2.The comparison between theδ18O record of WuLu Cave and the Ca2+ concentration record of GISP2 indicates that the intensity of the Asian summer monsoon and winter monsoon are anti-phase relationship in the study period. This indicates that atmospheric circulation changes are important in transmitting abrupt climate signals globally.The comparison between Wulu Cave and Greenland ice core record indicate that the frequency of centennial and millennial scale monsoon events match well with the temperature in North high latitude. Our monsoon characteristics more closely resemble, but are anticorrelated with, features in the Antarctic record and Brazil stalagmite record. This suggests some link to climate of the high southern latitudes. The mechanism is that the Asian monsoon intensity may be impacted by cross-equatorial flow through the temperature of southern ocean and the change of the vapor heat release. This indicates that the low-latitude monsoon and Antarctic temperature response to "see-saw" mode on centennial-millennial scales.