内蒙古银根盆地下白垩统沉积相

在对盆地周缘大量野外地质剖面详细测量的基础上结合室内分析，研究了银根盆地下白垩统巴音戈壁组的沉积相类型及其分布、演化。银根盆地下白垩统为典型的内陆湖盆沉积，形成了厚度达2000m以上的砂砾岩、泥岩夹碳酸盐岩、中基性火山岩，局部见油页岩和蒸发岩沉积，发育冲积扇、河流（以辫状河为主）、扇三角洲、三角洲、湖泊等沉积相类型。沉积体系的分布及演化主要受区域构造的影响，大致可以划分为三个沉积阶段，反映了断陷湖盆由发生、发展直至萎缩的一个完整旋回。早白垩世早期为湖盆初始断陷阶段，中期为强裂断陷阶段，晚期为湖盆萎缩阶段，每一沉积阶段在湖盆的不同部位发育了特定的沉积相类型及组合。

SEDIMENTARY FACIES OF THE LOWER CRETACEOUS OF YINGEN BASIN IN INNER MONGOLIA

The types of sedimentary facies of the Lower Cretaceous and their distribution and evolution in Yingen Basin are analyzed according to detailed survey and analysis on a lot of field geological sections around the basin. The sediments of the Lower Cretaceous in Yingen Basin are the typical interior lacustrine basin deposits, and there developed the sandstone, conglomerate, mudstone, carbonate rocks over 2 000 meters, with neutral to basic volcanic rocks and a little oil shale and evaporites. The types of sedimentary facies include the alluvial fan, stream (mainly braided stream, fan-delta, delta and lacustrine facies). The regional structural movements mainly controlled the sedimentary systems and their distribution and evolution. The sedimentary facies evolution can be approximately divided into three stages which reflects a full sedimentary cycle of a fault basin from formation and development to shrinkage. The early phase of the Early Cretaceous was an initial fault depression stage of the basin, and the middle phase of the Early Cretaceous was an intense fault depression stage and the late phase of the Early Cretaceous was a fault depression shrinkage stage. Each stage developed the specific sedimentary facies and facies assemblage in different positions of the basin.