伊宁凹陷金鑫煤矿侏罗系露头剖面层序地层分析

Sequence Stratigraphy of the Uutcrops of Jurassic Coal-Bearing Units in Jingxing Coal Mine of Yinin Sag,Xinjiang

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。

Based on the theories of the sequence stratigraphy and the sedimentary facies,this study investigates the characteristics of the sedimentary facies,the sequence boundary and the sequence stratigraphy of the Jurassic outcrop stratigraphic 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 Jurassic 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.