辫状河三角洲体系和湖底扇体系，构成了伊舒地堑下第三系最主要的粗粒碎屑沉积体系。它们以短轴方向搬运一沉积为主。盆地不对称双断导致沉降和沉积中心偏向于主断裂一侧，而辫状河三角洲体系则在缓坡一侧发育。辫状河三角洲体系作为地堑中的重要储集岩、它的发育与横向构造，如横向断层、断价、边坡以及基底凸起等构造单元有密切关系，因此，它们是油气勘探的重要靶区。 The braided delta system and the sublacustrine fan system constitute the most important coarse-grained clastic sedimentary system of the Tertiary in the Yishu Crag. They carry a deposition mainly in the direction of short axis. Asymmetric double faults in the basin resulted in the center of subsidence and sedimentation on the main fault, while the braided delta system developed on the gentle slope side. Braided river delta system, as an important reservoir rock in the graben, is closely related to the lateral tectonics such as lateral faults, fault price, slope and basement bump. Therefore, they are important for oil and gas exploration Target area.