Carbon isotope characteristics of Ordovician in Yubei area, Tarim Basin: A case study of well Pishanbei2

According to the analyses of 71 carbon isotope samples from Ordovician in the well Pishanbei2 in the Yubei area, GICE event was discovered for the first time under well in the Tarim Basin. The carbon isotope features of Ordovician were classified into three periods as followed. In the first period, it gradually increased in the lower and middle Yingshan Formation. In the second period, it varied nearby zero value from the upper Yingshan Formation to the lower and middle Lianglitag Formation. In the third period, the GICE event took place in the upper Lianglitag Formation. The carbon isotope values slowly raise from negative to positive in Ordovician, and broke into positive in the upper Lianglitag Formation in the study area.