内蒙古西部额济纳旗及邻区石炭系——二叠系沉积环境

Sedimentary environment of Carboniferous-Permian strata in Ejin Banner and its vicinities,western Inner Mongolia

为进一步研究额济纳旗及其邻区石炭系—二叠系沉积地质与盆地原型,根据研究区的岩性、岩相建造、古生物化石、沉积演化、沉积构造等基本数据,采用野外观察与室内研究相结合的方法,对额济纳旗及其邻区石炭系—二叠系的沉积环境进行了分析。额济纳旗及其邻区石炭系—二叠系受阿拉善古陆和北西方向海浸的控制,岩性特征受石炭纪—二叠纪构造单元的控制,岩性组合为碎屑岩+碳酸盐岩+火山岩。由南向北碎屑岩粒度变细,南部以滨岸环境的碎屑岩为主,北部以浅海陆棚环境和碳酸盐台地环境为主。额济纳旗及其邻区石炭系—二叠系沉积环境对优质烃源岩和储集层的发育具有控制作用。

This paper analyzed the sedimentary environment of Carboniferous-Permian strata in Ejin Banner and its vicinities for further researches on the sedimentary geology and basin prototype.Field observation was combined with in-house studies in the aspects of lithology,lithofacies construction,paleontologic fossil,sedimentary evolution and sedimentary structure.The results show that sedimentation of Carboniferous-Permian period in Ejin Banner and its vicinities is controlled by Alxa oldland and northwestern marine invasion,lithologic characteristics are controlled by structural units of Carboniferou-Permian strata,and lithologic association is clastic rock ＋ carbonate rock ＋ volcanic rock.The grain sizes of clastic rocks become gradually smaller from south to north： most clastic rocks of shoreland environment lie in the south,whereas most shallow continental shelf and carbonate plateau facies rocks are in the north.It is concluded that the sedimentary environment of Carboniferous-Permian strata in Ejin Banner and its vicinities controls high-quality source rocks and reservoirs.