Sterol distribution in sediments from Chaiwobu Lake and Caohai Basin and its geochemical significance

In order to understand the distribution characteristics of biomarkers in source rocks, which may be related to organic input, Quaternary sediments from the Caohai Basin and the Chaiwobu Lake were analyzed for sterols. As a result, various sterols have been found in the sediments. The composition of sterols in the sediments revealed that cholesterols and cholestadienols are more abundant than their C29 counterparts in the Chaiwobu Lake sediments and that C29 sterols are more abundant in the peats from the Caohai Basin. It is also found that stanol/sterol ratios in clays are higher than in peats. Studies show that organic input to the Chaiwobu Lake is mainly plankton and zooplankton and to the Caohai Basin is mainly terrestrial high plant. The authors have proposed that the relative abundance of C27 or C29 sterane in source rocks may reflect input characteristics to some extent and the stanol/sterol ratios may reflect the redox conditions of the depositional environments.