Middle Jurassic is the main layer system of hydrocarbon source rocks which develops widely in the Delingha depression. Field geological survey and organic geochemical analysis indicate that Middle Jurassic source rocks mainly include oil shale, mudstone, carbonaceous mudstone and coal.The oil shale is a good hydrocarbon-generating rock. Whose mass fraction of organic carbon averages 7.95％ and the type of organic matter is I and Ⅱ. Mudstone has different organic matter abundances,but over 80％ samples whose mass fraction of organic carbon is more than 1％ and over 65％ samples whose mass fraction of organic carbon is more than 1.5 ％. The type of organic matter of mudstone is Ⅱ and Ⅲ 1, and the mudstone is evaluated as poor to moderate source rocks. Carbonaceous mudstone whose mass fraction of organic carbon averages 10. 89 ％ and the type of organic matter is Ⅲ 1 and Ⅲ 2,so it belongs to poor hydrocarbon source rocks. The coal is the worst, and it belongs to a nonhydrocarbon source rock or poor hydrocarbon source rock. Most of the organic matter in the outcrop source rocks belongs to unbaked to low maturity, and a little of the organic matter belongs to maturity. It can be deduced that most of the organic matter in a peak period of oil generation and expulsion has a high maturity in the depression. The composition and the distribution of hydrocarbon compounds indicate that Middle Jurassic belongs to a fresh water deposit environment, and there develops semi-deep lake facies and deep lake facies which are good depositional settings to deploy source rocks in the Delingha depression.%柴达木盆地德令哈拗陷中侏罗统广泛发育,是该区主要的烃源岩层系.野外地质调查及有机地球化学分析表明,中侏罗统烃源岩主要以油页岩、泥岩、碳质泥岩和煤为主.油页岩有机碳的质量分数平均为7.95%,有机质类型属Ⅰ-Ⅱ型,为好生油岩;泥岩的有机质丰度交化大,但80%以上的样品有机碳的质量分数大于1%,65%样品的有机碳的质量分数达1.5%以上,有机质类型为Ⅱ-Ⅲ1型,综合评价为差-中等烃源岩;碳质泥岩有机碳的质量分数平均为10.89%,有机质类型为Ⅲ1-Ⅲ2型,综合评价为差烃源岩;煤岩最差,属非-差烃源岩.露头剖面烃源岩有机质大多处在未熟-低熟阶段,少量处于成熟阶段,推断拗陷内烃源岩有机质成熟度相对较高,正处于生、排烃高蜂期.烃类化合物组成及分布表明,中侏罗统属淡水沉积环境,拗陷内发育较深湖-深湖相优质烃源岩.
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