SHI Zhichao1,2 YANG Xunlin1,2 LIU Xiuming3 Li guojun1,2 SUN Xili1,2 WANG Baoyan1,2 FANG Moqin1,2 CUI Guyue1,2
(1. School of Geographical Sciences, Southwest China University, Chongqing 400715;
2. Karst Environment Laboratory, Southwest University, Chongqing 400715, China；
3. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China)
Abstract: High-resolution carbon isotope (δ13C) profiles of stalagmites from Shizi Cave in Chongqing Area, China were established with 15 230Th ages and 315 carbon isotope data, providing a continuous history of the surface vegetation condition for the period of 9.4–0 thousand years before present (ka BP, relative to AD1950). The δ13C record includes two distinct stages along with the evolution of EASM: (1) Lush vegetation period (9.4~3 ka BP)；during this period, the monsoon climate had been warm and humid, and the vegetation had been luxuriant, with C3 of surface vegetation cover. In the mid Holocene, δ13C did not show a tendency to follow the trend of δ18O, indicating that although the monsoon weakened, but the absolute humidity of ground surface environment had not changed but had been still suitable for C3 growth of vegetation. The climate had changed from warm and humid to cold and humid. (2) Environmental frequently changing period (3~0 ka BP); during the late Holocene, the monsoon recorded by the δ18O had been weak further, coupled with the impact of human activities, making the surface environment complex. Especially since 3ka BP, the correlation between the δ13C record and the content of organic carbon in the section of the Chongqing dam site has been obvious. A "natural profile" and "human site profile" correspond well. The results show that the vegetation types and their coverage have a profound influence on the changes of carbon isotope.
Keywords: Stalagmite; carbon isotope; surface vegetation; monsoon; karst valley
EARTH AND ENVIRONMENT Vol.46, No.2, Tot No.322, 2018, Page 138-145
