塔里木盆地寒武—奥陶系碳酸盐岩台地样式及其沉积响应特征

The Structural Types and Depositional Characteristics of Carbonate Platform in the Cambrian-Ordovician of Tarim Basin

从寒武纪到奥陶纪,塔里木盆地经历了早、中寒武世缓坡型碳酸盐岩台地,晚寒武世—早中奥陶世弱镶边斜坡型碳酸盐岩台地,晚奥陶世早期孤立型碳酸盐岩台地和晚奥陶世中晚期淹没型碳酸盐岩台地四种不同台地结构型式的演变。不同类型的碳酸盐岩台地在其剖面结构、台地边缘特征、沉积相构成等方面有着显著差异,它控制了不同区域沉积相类型和特征,并决定了烃源岩、储集岩和区域盖层的发育条件和展布规律。通过地震、钻井层序地层分析,总结出了不同类型的碳酸盐岩台地结构的层序—沉积相模式。在碳酸盐岩台地演变过程中,塔里木盆地发育二期坡折带:寒武纪—早中奥陶世形成第一期坡折带,沿着库南1井—满参1井—塔东2井一线分布,呈向西凸伸的弧形带;晚奥陶世发育第二期坡折带,由库南1井—满参1井—塔中1井—塘参1井延伸,呈向东凸伸的弧形带。坡折带的迁移变化,反映着台地样式的转变。

Tarim basin underwent the ramp carbonate platform of early-middle Cambrian, rimmed shelf carbonate platform of late Cambrian-early middle Ordovician, isolated carbonate platform in the early period of late Ordovician, and drowned carbonate platform in the middle-late period of late Ordovician. The different carbonate platform has distinct diversities in the section structure, platform edge feature and facies constitution, and controls the types and features of facies in the different regions and the upgrowth condition and the distribution rule of source rock, reservoir and caps. Through the sequence stratigraphy study of the seismic and loggings, 4 types of carbonate platform structure have been established and 5 sequence-facies models been summarized. During carbonate platform evolvement, two periods of platform slope are developed： The first platform slope is formed in Cambrian-early middle Ordovician, controlled by Well Kunan 1, WellMancan 1, WellTadong 2 route, represents arc belt toward the west. The second platform slope is formed in the late Ordovician, constrained by Well Kunan 1, WellMancan 1, WellTazhong 1 and WellTangcan 1, represents arc belt toward the east. The shifting and variation of the slope reveals the change of carbonate platform types.