【摘要】 为了查明鄂尔多斯西南缘奥陶系碳酸盐重力沉积的主要类型,探讨其成因机制以及古地理背景,对大量野外剖面和钻井岩心进行了系统观察。研究表明,奥陶系碳酸盐重力沉积丰富多样,主要发育岩崩、滑动、滑塌、碎屑流和浊流沉积。根据碎屑来源可将碳酸盐碎屑流划分为内源、外源、陆源及混源等类型,反映不同的成因机制和构造背景。研究后认为,鄂尔多斯地块早中奥陶世为广阔的克拉通陆表海浅水碳酸盐台地沉积,仅在西南缘有少量碳酸盐重力流发育。中奥陶世末克里摩里沉积期,鄂尔多斯西南缘演变为克拉通边缘拗陷-裂陷型陆缘海沉积格局,南缘大量发育碳酸盐滑塌-碎屑流-浊流沉积,西缘大量发育碳酸盐垮塌-碎屑流沉积。更多还原

【Abstract】 Based on the systematic observations of abundant outcrops and drilling cores in the southwest margin of Ordos,the main types of Ordovician carbonate gravity deposition are identified,and its genetic mechanism and palaeogeographic background are discussed. The result indicates that carbonate gravity deposition is well developed in Ordovician of the southwestern margin of Ordos,which mainly include rockfall,slide,slump,debris flow and turbidity flow. According to the source of clasts,the carbonate debris flow can be divided into endogenous,exogenous,terrestrial and mixed source types,reflecting the different genetic mechanisms and tectonic backgrounds. In Early-Middle Ordovician,the Ordos Basin was a vast shallow-water carbonate platform deposit in the craton epicontinental sea,only a small amount of carbonate gravity flow developed in the southwestern margin. Since the end of Middle Ordovician Kelimoli Period,the southwest margin of the Ordos began to evolve into depression-rift type pericontinental Sea of craton margin. In south margin,there developed amount of carbonate slump-debris flow-turbidity deposits and in west margin,carbonate collapse-debris flow deposits were more developed.更多还原