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根据岩心和薄片观察,塔河南缘S69—S76井的亮晶鲕粒灰岩和藻粘结灰岩与其它地区的微晶灰岩、亮晶砾砂屑灰岩及微亮晶砂屑灰岩形成对比,因而早奥陶世的沉积格局分界线应西移到库南2井—满参1井一线。依据岩性、岩石结构、沉积构造、剖面结构、古生物组合等标志,识别出下奥陶统有开阔台地相、台内浅滩相和台地边缘丘滩相3种沉积相类型;中上奥陶统为较深水陆棚相和潮缘沉积相。从层序地层学的角度将下奥陶统划分为海侵体系域和高水位体系域两个二级层序;中上奥陶统划分为海侵体系域、高水位体系域和低水位体系域。同时研究了层序和体系域的发育特征,初步确定了下奥陶统层序地层的对比方案。
According to the observation of cores and thin slices, the bright crystalline oolitic limestone and algal-bound limestone in the S69-S76 well in the southern margin of the Tahe River are similar to the other areas of microcrystalline limestone, bright gravel sandy litterstone and microlite crystal sandstone In contrast, the boundary line of sedimentary pattern of the Early Ordovician should be moved westward to Kunan 2 Well - Manchu 1 well. Based on the lithology, rock structure, sedimentary structure, profile structure and palaeontological assemblage, the authors identify three types of sedimentary facies of the Lower Ordovician including open platform facies, intraplate foreshore facies and marginal margin of the platform. Middle- For the deeper continental shelf facies and tidal sedimentary facies. The Lower Ordovician is divided into two second-order sequences of transgressive system tract and highstand system tract from the perspective of sequence stratigraphy. The middle-upper Ordovician is divided into transgressive system tract, highstand system tract and lowstand system area. At the same time, the developmental characteristics of sequence and system tract have been studied, and the contrast scheme of the Lower Ordovician sequence stratigraphy has been preliminarily determined.