塔中地区鹰山组高精度层序划分与对比

High Precision Sequence Division and Correlation of Yingshan Formation in Tazhong Area

塔中地区奥陶系包括下奥陶统蓬莱坝组、中-下奥陶统鹰山组和上奥陶统良里塔格组的碳酸盐岩地层,和上奥陶统桑塔木组碎屑岩地层,这些地层单元分别均以不同类型的不整合为界。其中良里塔格组沉积时限约为477.4~468.1ma,沉积时长约9.3 m.y.,小于大多数学者对二级层序年限的界定。本论文主要依据鹰山组的顶底界为受构造运动所形成的区域不整合,将良里塔格组作为1个二级层序来研究,最终建立了鹰山组内部层序格架模式。

The Ordovician in Tazhong area includes the carbonate strata of Penglaiba formation of Lower Ordovician,Yingshan formation of middle-lower Ordovician and Lianglitage formation of Upper Ordovician,and the clastic strata of Santamu formation of Upper Ordovician,all of which are bounded by different types of unconformity.The depositional time of Lianglitage Formation is about 477.4-468.1 Ma,and the depositional time is about 9.3 m.y.,which is less than the definition of the second-order sequence by most scholars.In this paper,the Lianglitage formation was studied as a second-order sequence according to the regional unconformity formed by tectonic movement in the top and bottom boundary of Yingshan formation.Finally,the internal sequence framework model of Yingshan formation was established.