川东南小河坝组砂岩成岩作用及其演化

The Sandstone Diagenesis and It's Evolution of Xiaoheba Formation in Southeast of Sichuan Area

本文通过普通薄片鉴定、铸体薄片鉴定、扫描电镜、X射线衍射以及阴极发光等多种实验测试手段对川东南地区小河坝组砂岩成岩作用以及成岩演化进行详细研究。研究结果表明:研究区小河坝砂岩主要为泥质石英粉砂岩、泥质长石石英粉砂岩、钙质粉砂岩,具有高石英、低岩屑的特点。成岩作用主要包括压实作用、胶结作用、交代作用以及溶蚀作用,成岩作用处于晚成岩B期。原生残余粒间孔是小河坝砂岩的主要孔隙类型。压实作用是造成原生孔隙减少的主要因素之一,溶蚀作用改善了砂岩的孔隙度,而胶结作用,尤其是钙质胶结造成次生孔隙进一步减少。

Based on variety of experimental test methods such as ordinary thin section,cast thin section,scanning electron microscopy,X-diffraction and cathodoluminescence,the sandstone diagenesis,and it＇s evolution of xiaoheba formation in southeast of sichuan area were studied.The results show that： the types of sandstone of xiaoheba formation mainly are argillaceous quartz siltstone,clay and feldspar and quartz siltstone,calcareous siltstone,which characteristic by high quartz,and low debris.The sandstone diagenesis includes compaction,cementation,replacement,and dissolution,the diagenesis is at the stage of B of later diagenetic.The main types of pores are the original intergranular pores,secondary porosity,intergranular pore and micro-cracks.Compaction is one of the mainly factors which cause the reduction of primary porosity,and dissolution improved the sandstone porosity,cementation,and especially calcareous cementation caused the secondary porosity further reduction.