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据构造活动及沉积层序充填特征分析 ,昌图凹陷地层层序可以划分为裂陷 (SSⅠ )、断陷 (SSⅡ )和坳陷 (SSⅢ )3个超层序 ,其中SSⅡ由SⅡ1、SⅡ2 两个层序构成。层序SⅡ1、SⅡ2 又可细分为低位体系域、湖盆扩张体系域、湖盆收缩体系域 ,发育有冲积扇、扇三角洲、前扇三角洲—半深湖、浅湖—沼泽相沉积体系。由于凹陷的幕式伸展造盆作用影响 ,凹陷断陷充填期曾两度湖泛 ,相应地在湖盆扩张体系域发育期充填了两套暗色泥岩密集段 ,从而形成了凹陷上下叠置的阜新组 (煤系烃源岩 )及沙海—九佛堂组 (湖相烃源岩 )两个含油气系统。
According to the tectonic activities and the filling characteristics of sedimentary sequence, the stratigraphic sequence of the Changtu Sag can be divided into three super-sequences of SSⅠ, SSⅡ and SSⅢ, among which SSⅡ consists of SⅡ1 and SⅡ2 A sequence of composition. The sequences SⅡ1 and SⅡ2 are subdivided into the lower system tract, the lake basin expansion system tract and the lake basin shrinkage system tract. There are alluvial fan, fan delta, fore-fan delta-semi-deep lake and shallow lake-swamp facies sedimentary system. Due to the effect of the curtain-forming extensional basin-forming, the depression faulted during the filling period of the depression faulted with two degrees of lacustrine flood. Correspondingly, two sets of dark mudstone intensive periods were filled during the development of the extensional system tract of the lake basin, thus forming Fuxin (Coal measure source rocks) and Shahai-Jiufotang Formation (lacustrine source rocks) two petroleum systems.