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通过对柴北缘地区的野外地质调查及室内实验分析,根据地质剖面中发育的岩石组合类型、沉积构造等特征,对研究区早奥陶世台地-斜坡-盆地相沉积体系进行了详细研究。认为研究区早古生代持续的海平面上升、柴北缘洋陆俯冲及陆弧碰撞是控制该时期盆山格局及沉积充填演化的重要因素。柴北缘早奥陶世台地边缘颗粒滩相发育在多泉山组中下部,岩性以生物碎屑灰岩、鲕粒灰岩以及泥晶灰岩为特征。而研究区斜坡相深水物质主要是由重力流搬运的碳酸盐岩再沉积物组成,共识别出包括细粒沉降微晶泥、滑塌角砾岩、颗粒流、瘤状灰岩、碎屑流以及浊积岩等不同类型的斜坡异地沉积物。研究区盆地相处于碳酸盐岩沉积体系-岛弧碎屑岩沉积体系两大沉积体系的转换位置。受到柴北缘洋陆俯冲及陆弧碰撞等影响,隆升的陆壳基底及大陆岛弧物质向盆地提供大量碎屑物质,因此在靠近岛弧边缘地区发育了砂质碎屑流、浊流等重力流沉积体系下的弧后盆地沉积产物。
Based on the field geological investigation and laboratory analysis of the northern Qaidam Basin, the Early Ordovician platform-ramp-basin facies sedimentary system in the study area has been studied in detail according to the types of rock assemblages and sedimentary structures developed in the geological section. It is considered that the sea level rise of the Early Paleozoic in the study area and the oceanic-subduction and continental arc collision of the northern Qaidam basin are important factors controlling the pattern of basin-mountain and the evolution of sedimentary filling during this period. The marginal granulitic facies of the Early Ordovician platform in northern Qaidam is developed in the middle and lower parts of the Duocushan Formation. The lithology is characterized by bioclastic limestone, oolite limestone and micrite limestone. However, the slope facies and deepwater materials in the study area are mainly composed of carbonate sediments transported by gravity flow. There are a total number of sedimentary micriters, slip-breccias, particle streams, Flow and turbidite and other different types of slope off-site sediments. The study area is located in the carbonate sedimentary system-island arc clastic sedimentary system, the two sedimentary system conversion position. Due to the influence of the submarine oceanic subduction and continental arc collision on the northern margin of the Qaidam basin, the uplifted continental basements and continental island arcs provide a large amount of debris to the basin, so sandy debris flow and turbidity flow are developed near the margins of the island arc Gravity flow sedimentary system in the backarc basin sedimentary product.