【摘要】 塔西南地区奥陶系碳酸盐岩中硅质发育，其产状和相态类型多样，但研究程度较低。本文以塔西南玉北地区钻井及塔北野外露头奥陶系中硅质为研究对象，通过岩石学及地球化学分析，对奥陶系碳酸盐岩中硅质赋存类型、富硅流体类型及来源、活动期次开展研究。研究结果表明，玉北地区奥陶系碳酸盐岩中硅质按产状差异可分为沉积型、充填型和交代型3种类型，沉积型硅质以低有序度的A型蛋白石和CT型蛋白石为主，充填型和交代型硅质以有序度相对较高的CT型蛋白石和石英为主。不同产状和相态类型硅质的地化性质表明其具有同源性。晚二叠世地温升高促使不同相态硅质的溶解度差异增大，并减弱了硅质转化的动力学屏障，从而促使沉积型硅质中低有序度相态硅质活化溶解，形成富硅流体，并以较高有序度的硅质充填或交代产出；断裂和溶蚀孔洞在空间上的配置关系控制了不同产状和相态硅质的空间分布。富硅流体活动改变了储集空间的空间配置，玉北地区富硅流体源于地层自身沉积型硅质的活化，原始均匀分布的A型蛋白石活化—运移—聚集到准同生溶蚀孔洞及裂缝中，一方面导致先期的储集空间被部分或完全充填，另一方面从原始沉积层中活化出的沉积型硅质所置换出的空间呈分散分布，基本无连通性。更多还原

【Abstract】 The Ordovician carbonate rocks in the southwestern region of the Tarim Basin are characterized by the development of siliceous rocks, with diverse occurrences and facies types, but the research level is relatively low. This article takes the drilling in the Yubei area of southwestern Tarim and the outcrop of siliceous rocks in the Ordovician in the field of northern Tarim as the research object. Through petrological and geochemical analysis, the occurrence types of siliceous rocks in the Ordovician carbonate rocks, the types and sources of silica-rich fluids, and the activity periods are studied. The research results indicate that the siliceous rocks in the Ordovician carbonates of the Yubei area can be divided into three types based on their occurrence: sedimentary, filling, and metasomatic. Sedimentary siliceous rocks are mainly composed of a low-order A-type opal and CT-type opal, while filling and metasomatic siliceous rocks are mainly composed of relatively a high-order CT-type opal and quartz. The geochemical properties of siliceous rocks with different occurrences and phase types indicate their homology. The increase in temperature during the Late Permian Period led to an increase in the solubility differences between different phases of siliceous rocks and weakened the dynamic barrier of siliceous transformation, thereby promoting the activation and dissolution of low-order phase siliceous rocks in sedimentary siliceous rocks to form silica-rich fluids, which then filled spaces or replaced minerals as higher-order siliceous rocks. The spatial distribution of siliceous rocks with different occurrences and phases was controlled by the spatial configuration relationship of fractures and dissolution pores. The activity of silicon-rich fluids has changed the spatial configuration of reservoir space. In the Yubei area, silica-rich fluids originate from the activation of sedimentary siliceous rocks in the formation itself. The original uniformly distributed A-type opal was activated, migrated, and aggregated into quasi-syngenetic dissolution pores and fractures. On the one hand, this leads to partial or complete filling of the early reservoir space. On the other hand, the space displaced by sedimentary siliceous rocks activated from the original sedimentary layers is also dispersed, with poor connectivity.更多还原