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从区域沉积背景出发,利用岩心、地球化学等资料分析了研究区沙四段(Es4)烃源岩的岩性和沉积特征,认为烃源岩发育在湖盆水进阶段,湖盆面积广、水深大.并详细研究了烃源岩的地球化学特征,总结出该套烃源岩的成烃特征和判识标志:该套烃源岩DBT/P值>1,伽玛蜡烷指数>0.2,甲藻甾烷不发育,三芳甲藻甾烷发育程度较低,甾烷/藿烷比值为0.10~0.28,δ13C变化相对较小且偏负;烃源岩中的灰质成分发育,表现出碳酸盐岩生烃特征;同时由于水深较大,也有高硫的特点.“,”Based on cores,geochemical and other data,in addition to regional sedimentary background,we studied the lithology and sedimentary characteristics of source rocks of Es4 in the Bonan Depression.The source rock was formed in a wide deep basin and characterized by DBT/P value greater than 1,gammacerane index greater than 0.2,undeveloped dinosterane,lower developed triaromatic steranei,a sterane / hopane ratio of 0.10 ~ 0.28 and negative δ13C with relatively small variation.Carbonate content is rather high indicating a carbonate hydrocarbon.The high content of sulfur suggests a larger water depth.