THE CHARACTERISTICS OF BIOMARKER ASSEMBLAGE AND ITS SIGNIFICANCE IN THE IMMATURE SOURCE ROCKS FROM EASTERN DEPRESSION, LIAOHE BASIN, CHINA

The characteristics of biomarker assemblage in the Early Tertiary imma ture source rocks from the third member (Es-3) and the first member (E s-1) of the Shahejie Formation, Eastern Depression, Liaohe Basin, Chin a, are summarized. There is a strong odd-carbon number n-alkane predom inance in the C-23-C-31 range with a maximum at nC(27) or nC(29). The occurrence of abundant resin-type biterpenoids and angiosperm-derived triterpenoids indicate the importance of higher plant input to sedimen ts, while the presence of 4-methylsteranes in the Es-1 and some Es-3 s amples reflect the significant contributions from aquatic organism, i. e. dinoflagellates. In contrast, terrigenous higher plant is the major origin of organic matter in Er-3 source rocks, and in Es, source rock s, the origin of organic matter is characterized by the mixture input of aquatic organisms and higher plants. In both typical terrestrial be ds, relatively high concentration of dinosteranes, which may be derive d from some specific freshwater dinoflagellates, were detected.