蒙古国塔木察格盆地南贝尔凹陷铜钵庙组–南屯组的主要沉积特征Main Sedimentary Characters of the Tongbomiao-Nantun Formations in the South Buir Sag, Tamtsag Basin in Mongolia
吴根耀, 高庚, 朱德丰, 王金奎, 刘绍军, 孙效东, 刘赫, 李春柏, 李强, 张革
扇三角洲, 近岸水下扇, 湖泊, 砂体展布, 下白垩统, 南贝尔凹陷, 塔木察格盆地Fan Delta, Inshore Underwater Fan, Lacustrine, Sand Body’s Distribution, Lower Cretaceous, The South Buir Sag, The Tamtsag Basin
《Advances in Geosciences》, Vol.5 No.6, 2015-12-15
The Tongbomiao-Nantun Formations, in age of Early Cretaceous, are deposits of fault-depressing stage of the South Buir Sag, Tamtsag Basin in Mongolia. To synthesize the core sample observations, laboratory works, logging data and seismic facies signs, the paper illustrates the distinguished marks of each sedimentary facies, summarizes the main characteristics of each facies, sub-facies and micro-facies, explores the spatial distribution of the sand bodies and sedimentary facies belts, then analyses the controlling factors of environments and tectonic settings, as well as oil-gas exploration significances. The Tongbomiao Formation is a sedimentary record of the initial rifting-depressing phase, which is mainly composed of fan deltaic facies, and subordinate lake-shore-shallow lacustrine facies. In addition, there develop the pluvial/fluvial fan facies in the No. 1 member and inshore underwater fan facies in the No. 2 member of the formation in the West Sub-Sag. The No. 1 Member of Nantun Formation records a phase of sustained rifting-depressing, which is characterized with inshore underwater fan facies and deep/median deep lacustrine facies. Furthermore, there exist sediments with fan deltaic facies and lakeshore-shallow lacustrine facies. The depositing period of the No. 2 Member of Nantun Formation might be, actually, a transitional phase from the fault-depressing stage to the shear-subsidence stage (sedimentary period of the Damoguaihe-Yimin Formations). During this time, the lakeshore-shallow lacustrine facies are widely occurred, and the distribution scope of fan deltaic facies is extensively reduced. Moreover, delta appears in the southern part of the sag, and becomes main sedimentary facies in depositional period of the Damoguaihe Formation.