The Different Responses Of The Asbestos Oxygen And Carbon Isotope Records To The Holocene Climate

The Asian monsoon is an important part of the global monsoon system, affecting on the production and living of half of the world's population. It is also the link between the world's largest land and sea, which has. an important impact on global climate evolution. Stalagmites are considered to be one of the best materials for the study of monsoon evolution and play an important role in the multi-scale evolution study of the monsoon. In the thesis, a stalagmite was collected from high altitude Xi'niu cave, Shennongjia, Hubei province. A time series of East Asian Summer Monsoon precipitation evolution and mean annual temperature evolution from 13.1 to 2ka BP with average resolution of 9.63a is reconstructed based on the 14 high-precision U/Th dates and 1146 ?18O and ?13C data.On orbital timescale,the evolution of the East Asian Summer Monsoon precipitation is consistent with the 35°N summer solar radiation curve and the titanium concentration curve in the Carriaco Basin. This pattern is similar to that of migration of the Inter-Tropical Convergence Zone (ITCZ) positions due to the change of summer insolation of the northern hemisphere. On millennial-centennial timescale,the evolution of the East Asian Summer Monsoon precipitation is consistent with other cave stalagmites records in Asian Monsoon area, YD events and centennial to millennial scale oscillations throughout the Holocene are consistent with the millennial scale ice-rafted debris (IRD) events in the North Atlantic Ocean. Different dynamical processes such as meltwater flux into the North Atlantic,low solar activity,explosive volcanic eruptions, etc., likely played a major role. However, it may also be only the internal shock of the climate system.The Indian Summer Monsoon and the East Asian Summer Monsoon are broadly in phase during the Holocene based on the comparative study of Xi'niu cave stalagmite and other cave stalagmites, lacustrine sediments and loess. And Holocene optimum is broadly synchronous across the monsoon region, which occurred between 10 and 5ka BP.The results show that the 813C of high altitude Xi'niu cave stalagmite may represent the evolution of the vegetation affected by the mean annual temperature based on the comparative study of Xi'niu cave stalagmite and other cave stalagmites,pollen, peat, lacustrine sediments and marine deposit, which is obviously different on the evolution of the summer monsoon rainfall. The ?13C data are characterized by centennial to millennial scale oscillations throughout the Holocene that broadly correspond to the millennial scale ice-rafted debris (IRD) events in the North Atlantic Ocean, indicating that the mean annual temperature change was closely related to the North Atlantic Ocean ice-rafted debris (IRD) events at millennial-centennial timescale,which may be more sensitive to ocean circulation.The differences in ?18O and ?13C records of cave stalagmites in the Asian monsoon region may be related to different climatic significance that they represent respectively during the Holocene. The Asian Summer Monsoon precipitation represented by ?18O data is more sensitive to the summer solar insolation in the northern hemisphere, the mean annual temperature represented by ?13C data is more sensitive to greenhouse gas, ice volume, ocean circulation, so the mid-late Holocene two decoupling also proved that they were affected by different driving factors.