内蒙古西部银额盆地及邻区晚古生代海平面变化与沉积响应

晚古生代银额盆地发育一套石炭纪—二叠纪火山岩-碎屑岩-碳酸盐岩,沉积建造稳定,岩相清晰,地层层序和沉积体系域发育清楚。通过对区内沉积盆地地层特征和侧向变化分析,初步划分出了4个Ⅱ级层序,8个Ⅲ级层序,识别出若干个沉积体系域和层序界面,沉积层序具有伸展型层序特征,Ⅲ级层序Ⅰ、Ⅳ、Ⅵ、Ⅶ、Ⅷ形成过程中盆地海平面上升速度快,对形成厚度大的暗色泥岩层有利。盆地沉积演化与构造活动密切相关,构造活动控制了海平面的变化。通过区域地层格架分析和层序地层学研究,可以进一步研究区域构造活动历史,从而更好地预测暗色泥岩和有利储层形成的有利环境。

Late Paleozoic sea level change and sedimentary response in Yin- gen-Ejin Banner basin and its adjacent areas, western Inner Mongolia.

Late Paleozoic Yingen-Ejin Banner basin characterized by stable sedimentary formation, clear lithofacies, distinct stratigraph- ic sequence and depositional system tract has developed a set of Carboniferous-Permian volcanic rocks, clastic rocks and carbonates. Based on an analysis of formation characteristics and lateral variation in this sedimentary basin, the authors divided preliminarily the basin into 4 II-grade sequences and 8 ]]I-grade sequences, and identified several depositional system tracts and sequence interface. The rising velocity of the basin sea was quick during the formation of Ⅰ, Ⅳ, Ⅵ, Ⅶ ,Ⅷ in Ⅲ -grade sequence, which was conducive to forming a large thickness of dark mudstone. Sedimentary sequence had a stretching feature. The evolution of sedimentary basins was closely related to tectonic activities, and tectonic activities controlled the sea level change. The history of regional tectonic activities could be further studied through regional stratigraphy and sequence stratigraphy analysis, so that the favorable environment for dark mndstone formation could be predicted.