Sedimentary Environments and Generation Potentials of the Possible Source Rocks in Jurassic System in the Eastern Qaidam Basin,China

In order to the investigation on the Sedimentary Environments and Generation Potentials of the Possible Source Rocks in the Jurassic System in the Eastern Qaidam Basin,the rock samples selected from the outcrop in the Jurassic System were analyzed including the organic carbon content,the parameters of pyrolysis,biomarker characters of saturated hydrocarbon and stable carbon isotope quality of individual n-alkanes by means of Rock-Eval,GC-MS,GC-MS-MAT and so on.The results showed that: the content of organic carbon ranged from 0.07% to 56.8%,most of the source rocks were type Ш of kerogen,a few of the source rocks were type Ⅱ of kerogen and few were type Ⅰ of kerogen.Gray-black oil shale and black charcoal shale were high quality source rocks in Jurassic system comparatively.The value of the parameters of C_(29)ααα20S/(20R+20S)and C_(29)αββ/(αββ+ααα)was 0.06～0.34 and 0.25～0.35,and the organic matter was being in the stage of low maturity.The organic matter was mostly deposited in an environment of lake beach,shallow lake and marsh with oxidation,showing the characters of coal-measure rocks.A few of rock samples revealed a reducing environmentof semi-deep lake or deep lake with high salty and water column stratification.