伊宁凹陷金鑫煤矿侏罗系露头剖面层序地层分析

摘要

Based on the theories of the sequence stratigraphy and the sedimentary facies,this study investigates the char-acteristics of the sedimentary facies,the sequence boundary and the sequence stratigraphy of the Jurassic outcrop strati-graphic section from the Jingxing coal mine in the northern margin of the Yining sag,Xinjiang.The results show that the alluvial fan,braided river,meandering river, delta and shore-shallow lake sedimentary systems are developed in the Juras-sic outcrops;The sequence boundaries are characteristic by erosion unconformity and intense downcutting of the river channel; Based on the sequence boundaries,3 third-order sequences in Badaowan formation,2 third-order sequences in Sangonghe formation,and 2 third-order sequences in Xishanyao formation are distinguished,respectively;The low-stand system tracts are mainly composed of alluvial fan and braided river sedimentary facies,the lake-expansion system tracts are mainly composed of shore-shallow lake facies,and the high-stand system tracts mainly of delta and meandering river sedimentary facies.The peat bog are mainly developed in the lake-expansion and high-stand system tracts.%　　以伊宁凹陷北缘霍城县金鑫煤矿侏罗系露头地层剖面为研究对象，采用层序地层学和沉积相分析方法，对其层序界面特征、层序的构成特征和沉积相类型进行研究。结果表明，侏罗系露头剖面发育冲积扇、辫状河、曲流河、三角洲和滨浅湖等沉积相类型；层序界面以侵蚀不整合面和河道强烈侵蚀下切面为识别标志。依据确定的层序界面，在八道湾组中划分3个层序、三工河组和西山窑组中分别划分2个层序。低位体系域主要发育冲积扇和辫状河沉积体系，湖扩体系域主要发育滨浅湖沉积，高位体系域主要发育三角洲和曲流河沉积体系。泥炭沼泽主要发育于湖扩体系域和高位体系域。