鄂尔多斯地区晚古生代的海侵

Transgression of Late Paleozoic Era in Ordos Area

陆表海具有多旋回幕式海侵和慢速海退的特点．依据新的地层划分方案和含蜓地层的研究成果，通过对鄂尔多斯地区晚古生代地层中海相层的追索对比，指出晚石炭世早期西部的祁连海和东面的华北海互不连通，晚石炭世晚期沿北侧汇合；早二叠世形成统一陆表海；中二叠世至晚二叠世早期沉积盆地为一近海内陆坳陷，间或受到海泛作用影响；晚石炭世可能与北侧兴蒙海槽局部连通；海侵作用受控于区域构造活动和海平面升降．

Using the new program of stratigraphic division, the study results of fusulinid bearing strata, and the correlation of marine facies beds of late Paleozoic strata in Ordos area, the authors have drawn the following conclusions: there was no connective passage between the western Qilian Sea and eastern North China Sea during the early late Carboniferous; in late late Carboniferous the western sea connected with the eastern at the northern part; a united inland sea was formed in the early permian owing to sea water flowing over the central paleouplift; from middle permian to early late Permian, the sedimentary basin was a paralic one that had some connection with open sea and sometimes was influenced by ingression. It is proposed that Ordos area may have partial connection with northern Xingan Mongolia Trough. The transgression was controlled by area tectonism and was closely interrelated to fluctuation of sea level.