关键词: 海侵, 生物标志物, 甲藻甾烷, C₃₁甾烷, 松辽盆地

Abstract: The relative high abundance of dinosterances has been found in the member No.1 of Qingshankou Formation and the members No.1 and No.2 of Nenjiang Formation based on the geochemical studies of source rocks in Songliao Basin.The widely distributed dinosterance in source rocks indicates that there were two periods of marine transgression in geological history.The relative content of dinosterane in source rocks in the member No.1 of Qingshankou Formation is higher than that in the members No.1 and No.2 of Nenjiang Formation.In addition,C₃₁steranes have been identified only in the source rocks of member No.1 of Qingshankou Formation.This is not only attributed to differente algae in these formations,but also related to the differences between ancient sedimentary environment and the salinity in source rocks.The molecular fossil assemblage shows the relatively high salinity in source rocks of the member No.1 of Qingshankou Formation.It may indicate wide marine transgression in the period of the member No.1 of Qingshankou Formation sedimentation.The content of dinosterane has been tentatively used to determine the direction of marine transgression.

Key words: marine transgression, biomarker, dinosterane, C₃₁sterane