Correlation of Environmental and Climatic Change Between Qaidam Basin Gamma Ray Logging Curve and Guliya Ice Core δ~(18) O Record Since the Last Interglacial Cycle
YUAN Lin wang, CHEN Ye, ZHOU Chun lin, LIU Ze chun (Geo-Science School of Nanjing Normal University, Nanjing Jiangsu 210097, China) [HT]
The Qaidam basin is a very large, arid, intermountain, sedimentary basin in western China. It is located to the north of the Tibetan Plateau. Core Dacan-1 was extracted from the east of the Qaidam Basin, due to great thickness, high continuity and fine material composition, the resolution of the core is high, which provides the necessary and sufficient basis for studying the Quaternary paleoclimatic changes in the basin. A natural gamma ray(GR) logging curve of Borehole Dacan-1 was used to inverse paleoclimate change in the basin. The process of environmental change during the last interglacial cycle has been revealed. The variation of GR logging curve can reflects environmental and climatic change, and it can be matched well with those recorded in Guliya ice core and Greenland ice core. The consistency confirms that the ancient global climate change is comparable, and the climate system has its own evolution process. During the transition of warm stage to cool stage, GR logging curve shows the same characteristics with Greenland ice corerecords,ut is opposite to the Guliya ice coreδ 18 Orecord. This difference shows that different proxy indicators in different regions may have its own characteristics, and it may own different sensibility and reflect regional factors. GR logging curve also reveals regional environmental change in the Qaidam Basin, which well reflected uplift of the Tibetan Plateau, and can be confirmed by the Guliya ice core δ 18 O record and other correlative studies. Tectonic and climatic events can be identified by the variability of GR logging curve. This suggests that GR logging curve is a sensitive proxy indicator of environmental and climatic changes. It also indicates that the Qaidam Basin, one of the inland paleo-lake is a well information carrier of climatic and environmental change, and it may faithfully record the process and stages of the uplift of Tibetan Plateau. GR logging curve reflects the combined actionof tectogenesisand climatic change. When properly defining the reflection of tectogenesis, more comparable climatic change information can be obtained. Based on the environmental and climatic information deduced from the GR logging curve in the Qaidam Basin, lacustrine deposits of longer time interval and shorter time scale can be extrapolated.