内蒙古苏尼特左旗地区二叠纪地层的划分与对比

SUBDIVISION AND CORRELATION OF PERMIAN STRATA IN SONID ZUOQI AREA,INNER MONGOLIA

本文讨论了内蒙古苏尼特左旗地区二叠纪地层单元的划分及其接触关系，认为本区二叠纪地层应包含大石寨组与哲斯组，缺失晚二叠世沉积；描述了代表本区地层序列演化的典型剖面，并对各单位在区域上的延伸及其对比关系进行了简述，认为本区二在纪地层的区域对比应以火山事件沉积为主线，以地层序列演化及生物化石为标志，而不应以岩性相及厚度为主要依据；根据区域地层序列演化分析，认为大石寨组与哲斯组之间的不整合是本区构造事件的代表性界面。

he authors discuss the subdivision and correlation of Permian strata in Sonid Zuoqi area,Inner Mongolia and demonstrate several contact relationship of the stratigraphic units.The results show that the stratigraphic units should embrace the Dashizhai Formation and Zhesi Formation which is dated to Early Permian.The typical section which includes all the stratigraphic units is described and the extent relationship of these stratigraphic units is also discussed.The authors consider that the correlation of Permian strata in this area should emphasis the deposits of volcanic event and the evolution of stratigraphic sequence and the fossils deposited in the strata.The correlation based on lithofacies and thickness will possibly blind the eyes of field workers.The data also indicates that the nonconformity between Zhesi Formation and Dashizhai Formation is probably the key boundary representing the transitional tectonic event.