Abstract：
The Upper Cretaceous oil shale in the northern Songliao Basin might belong to middle and relatively bad one.There were two types of organic matters in the oil shale(Ⅰ and subordinate Ⅱ1 types ).The oil shale was in the lower-maturity stage, and the maturity of the oil shale in Qingshankou Formation was higher than that of Nengjiang Formation.The biomarker combinations, including n-alkanes, isoprenoid, terpanes and steranes, were similar in the both formations.The n-alkanes showed a dominance of high carbon molecular components with the highest peaks of nC23 or nC27.OEP values of the n-alkanes showed obvious odd carbon dominance.Pr/Ph ratios were 0.13-1.37, which indicated the oil shale possessing phytane dominance.There was a higher abundance of gammacerane in the oil shale.The biomarker's parameters reflected that the depositional environment should be reduction condition,with high salinity.The terpanes distribution patterns of oil shale samples were pentacyclic terpanes> tricyclic terpanes.The terpanes consisted mainly of C20-tricyclic terpanes, C21-tricyclic terpanes and C23-tricyclic terpanes.According to abundance of C23>C21,, the steranes consisted mainly of C27- steranes, C28-steranes and C29-steranes, and the abundance of C29>C27>C28.All these biomarker's characteristics indicated that the organic matters of the Upper Crataceous oil shale in the northern Songliao Basin should be of sigae origin,with proper contribution from terrestrial plant.
. A preliminary study on geochemical characteristics and depositional environments of oil shale in the northern Songliao Basin[J]. Chinese Journal of Geology, 2009, 44(2): 457-467.
2009, Vol. 44 
