黔北道真地区上奥陶统五峰组—下志留统龙马溪组沉积微相研究

A sedimentary microfacies study on Wufeng formation-lower Silurian Longmaxi formation of upper Ordovician in Daozhen area,northern Guizhou Province

上奥陶统五峰组—下志留统龙马溪组是我国南方地区页岩气勘探开发的主要目标层系之一,但对其沉积微相的研究较为薄弱。文章以黔北道真地区为例,通过多条野外剖面和钻孔资料对比研究,结果显示上奥陶统五峰组—下志留统龙马溪组整体属于陆棚相,分属深水陆棚、半深水陆棚两个亚相。其中五峰组及龙马溪组下部属于粉砂质碳泥棚微相,龙马溪组中部属含粉砂质碳泥棚微相,龙马溪组上部属含钙质粉砂质碳泥棚微相。该认识对于黔北地区页岩气有利区的优选具有指示意义。

The upper Ordovician Wufeng formation to the lower Silurian Longmaxi formation is one of the main target strata for shale gas exploration and development in southern China,however,the research on its sedimenta⁃ry microfacies is relatively weak.In this study,the comparative study by several field sections and borehole data shows that the upper Ordovician Wufeng formation and lower Silurian Longmaxi formation belong to the continen⁃tal shelf facies as a whole,which can be subdivided into deep water shelf and shallow water shelf subfacies.The Wufeng formation and the lower part of Longmaxi formation belong to silty carbon mud shack microfacies;the middle part of Longmaxi formation belongs to silty carbon mud shack microfacies,and the upper part of Longmaxi formation belongs to calcareous silty carbon mud shack microfacies.This study is of indicative significance for the optimization of favorable shale gas areas in the northern Guizhou area.