川东地区上二叠统大隆组页岩硅质成因及其与有机质富集的耦合关系OA

Objectives:In the late Permian period,influenced by the mantle plume event of Mount Emei,a set of organic-rich siliceous shale was deposited in the Kaijiang-Liangping trough on the northern margin of the Sichuan Basin.This set of siliceous shale lacked the input of continental materials and was formed in a typical clear water sedimentary environment.The siliceous genesis of this set and its coupling relationship with organic matter enrichment were studied,and on this basis,the development model of siliceous shale was established.In order to provide a reference for the exploration and development of Permian shale gas.This paper takes the Marine shale of the Dalong Formation of the Upper Permian in the eastern Sichuan region as the research object and conducts detailed core observation,micro-petrological analysis and whole-rock geochemical analysis. Results:① The lithology of the organic-rich mud shale section of the Dalong Formation is mainly siliceous shale,with a relatively high organic matter abundance,an average TOC of 7.26％.The mineral types are mainly quartz minerals,followed by carbonate minerals,and the content of clay minerals is relatively low.② Siliceous organisms mainly come from biological sources.The deep silicon-rich water bodies brought about by upwelling and the overall silicon-rich seawater caused by regional tectonic events provide conditions for the prosperity of siliceous organisms.③ The enrichment of organic matter is closely related to the enrichment of siliceous matter.The enrichment of both organic matter and siliceous matter in siliceous shale is simultaneously controlled by high primary productivity and the preservation conditions of anoxic-sulfidation reduction environment. Conclusions:It reveals that there is a coevolutionary mechanism between the siliceous genesis of shale and the enrichment of organic matter.