内蒙古林西地区上二叠统林西组三段沉积环境分析

Sedimentary environment analysis of the third member of Upper Permian Linxi formation in Linxi area,Inner Monglia

针对林西组兴-蒙地区晚二叠世地层沉积环境一直具有争议的问题,选取林西组第三段(简称林三段)为主要研究对象,对林三段标准剖面进行野外实地测量,收集古生物化石、岩石样品和沉积构造等资料,结合岩层产出序列特征进行综合分析。结果表明:林三段沉积期林西地区存在广阔的海域;林三段砂体为三角洲沉积体,识别出三角洲前缘、三角洲平原和前三角洲3种亚相,河漫沼泽、分流河道、泥石流、水下分流河道、分流河道间、河口沙坝、前缘席状砂和前三角洲泥8种沉积微相。

Linxi formation is the important strata of late Permian in Xing-Meng area, its sedimentary environment has been con- troversial. In this study, the third member of Linxi formation （Lin Third Member for short） was selected as the research object, and the field measurements for the main section of Lin Third Member were carried out, information for ancient biological fossils, rock samples and sedimentary structures etc, was collected and then comprehensive analysis was done combined with the sequence characteristics of strata. The results show that the deposition period of Lin Third Member has broad seas in Linxi area. Lin Third Member is delta sedimentation it is divided into three kinds of sedimentary subfacies including delta plain, delta front, former delta, and eight kinds of sedimentary microfacies including flooding swamp, distributary channel, debris flow, under water distributary channel, interdistributary channel, channel mouth bar, front sheet sand and predelta mud.