鄂尔多斯盆地中生代构造事件及其沉积响应特点

以鄂尔多斯盆地中新生代构造演化的区域动力学环境分析为基础,重点通过锆石和磷灰石裂变径迹年龄数据的统计分析,提供了鄂尔多斯盆地中新生代构造事件的年代学约束,并结合地层不整合关系和沉积建造特征讨论了中生代构造事件的沉积响应特点.讨论结果表明:印支期构造事件主要发生在230~190Ma,在盆地西南缘发育晚三叠世粗碎屑类磨拉石建造.燕山期构造事件主要发生在燕山中晚期的150~85Ma,包含145Ma±、120Ma±和95Ma±三个峰值年龄组,锆石和磷灰石裂变径迹年龄叠合分布的峰值年龄(140~150Ma±,平均145Ma±),指示了鄂尔多斯盆地中新生代构造演化过程中最为关键的一次构造变革事件,并在盆地西南缘发育上侏罗统芬芳河组和下白垩统志丹群等多套粗碎屑类磨拉石建造.

Mesozoic tectonic events in Ordos Basin and their sedimentary responses

Based on the analysis of the regional dynamic environment of the tectonic evolution of Ordos Basin from Mesozoic to Cenozoic, the age data of the tectonic events of the basin happening in the stage are provided by means of the analyses of the statistic data of the fission track ages of zircon and apatite. And the sedimentary responses of the tectonic events are discussed through the analyses of the relationships among the unconformities and the characteristics of the sedimentary formations in the basin. It is shown that, the Indosinian tectonic events mainly occur in the stage of 230- 190 Ma, and a set of coarse molasses clastic deposit correspondingly develops on the southwestern border of the basin during the Late Triassic; the Yanshanian tectonic events mainly occur in the stage of 150-85 Ma, including three statistic peak ages of 145 Mai , 120 Maand 95 Ma. Especially, the peak age of 140-150 Ma(average age 145 Ma indicates a key tectonic event of the basin in Mesozoic-Cenozoic, and several sets of coarse molasses clastic deposits correspondingly develop on the southwestern border of the basin in Fenfanghe Formation of the Upper Jurassic and Zhidan Group of the Lower Cretaceous.