靖边-安塞地区延长组长1段沉积相特征

目的探讨鄂尔多斯盆地靖边—安塞地区三叠系延长组长1段的沉积相特征及展布。方法根据野外考察资料,利用地层对比及测井相分析方法,划分了靖边—安塞地区长1段沉积相类型。结果靖边—安塞地区晚三叠世末期为湖泊—三角洲沉积环境,沉积中心在子长地区;沉积相自下至上依次为三角洲平原、三角洲前缘和前三角洲—深湖;沉积序列自下至上以粒度由粗到细的正旋回为主。结论长1期湖盆的演化受鄂尔多斯盆地中部东西向构造带控制,该湖盆中的湖相暗色泥岩有可能成为子长等地区另一套重要的烃源岩。

Depositional feature of the Chang 1 of Yanchang Formation in Jingbian-Ansai Area, Ordos Basin, China

Aim To discuss the characteristic and distribution of sedimentary facies of the Member 1 of Yanchang Formation,Upper Triassic in Jingbian-Ansai Area in Ordos Basin.Methods The main methods used in the study include the fieldwork of geological survey,stratigraphic classification,and electrofacise analyses.Facies maps have been drawn according as the rate of sand.Results Research results indicated that the sediment environment in Hengshan,Zichang,Ansai and Jingbian Area in Ordos basin was lacustrine-delta in the end of Late Triassic.The depression center was located in Zichang Area.The lacustrine-delta sequence in the Chang 1 of Yanchang Formation is featured with a fining upward: the delta-plain in the bottom,delta-front located in the lower part and the pre-delta in the middle and the deep lacustrine facies in the upper part.Conclusion The transmeridional structure belt of the middle of the Ordos Base controlled the evolution of the lake.The shale of the deep lake may be the other important source rock in Zichang Area.