银额盆地及周缘石炭系和二叠系沉积之后构造改造初探

通过银额盆地周缘野外地质调查,结合岩石薄片显微构造、磷灰石裂变径迹研究,以及盆地内部综合物化探与地震剖面、钻井等资料,对银额盆地及周缘晚古生代与中新生代地层构造变形及改造进行了分析,并对石炭系与二叠系后期构造改造期次及动力学机制进行了初步探讨。就石炭系和二叠系构造变形而言,露头区构造变形强于盆地内部,北山地区变形程度强于洪格尔山地区。石炭系与二叠系主要遭受了华力西末期、早中燕山期、燕山晚期、喜马拉雅期构造改造作用。第一期变形强烈,以差异隆升为主;第二期区域上变形最强烈,主要表现为区域抬升及大规模的逆冲推覆构造;第三、四期主要为轻微的差异升降作用,分别受控于太平洋板块向华北地块俯冲和印度板块向欧亚大陆俯冲的远程效应。石炭系与二叠系多套烃源岩于早白垩世末期达到最大埋深,进入主要生烃期,早白垩世以来受后期构造改造较弱,形成的大面积河湖相沉积可作为有效的储层与盖层,为银额盆地油气成藏提供了良好的生储盖条件。

A preliminary study of the structure and reformation of the Permian and Carboniferous strata in Yingen-Ejin basin and its periphery

In this study, structure deformation features of the Carboniferous, Permian and Meso-Cenozoic strata were analyzed in Yingen-Ejin basin and its periphery, and geological survey was conducted mainly based on geophysical prospecting and drilling in the interior of the basin. The deformation of the Carboniferous and Permian outcrops is stronger than that in the interior of the basin, and stronger in Beishan than in Honggeershan. The tectonic deformation stages and dynamic mechanism after Permian were preliminarily discussed. Four tectonic stages, i.e., Late Variscan, Early Yanshanian, Late Yanshanian and Himalayan tectonic movement, were distinguished. The deformation was strong in the first period. The second phase deformation is the strongest in the region in that large-scale nappe structure and regional uplift were formed during this period; the overall tectonic pattern was formed in the Late Jurassic. The third and fourth stages were mainly characterized by differential uplifting and subsidence, with the dynamic mechanism being separately controlled by the remote effects of the subductions of the Pacific plate under the North China block and the subduction of the India plate under the Eurasia. The source rock of Carboniferous-Permian was buried most deeply with the formation of oil until the end of Early Cretaceous. Furthermore, the structural activities were insignificant after the Early Cretaceous, which was favorable for the formation of hydrocarbon reservoir.