长石砂岩次生溶孔的形成机理

在酸性水介质条件下,长石类矿物都能发生程度不同的溶蚀反应并形成次生孔隙。根据原始矿物和次生矿物的组成和物理化学性质可以定量计算次生孔隙度。钾长石被溶蚀时形成的次生孔隙度最高,达11.91%,钙长石形成的次生孔隙度最低,为0.72%,钠长石和中长石形成的次生孔隙度介于两者之间。长石溶蚀过程中所需的CO₂,一部分来自大气降水或水与大气接触过程中所溶解的空气中的CO₂,另一部分则来源于有机质在生烃过程中的分解产物。

Formation mechanism of secondary dissolved pores in arcose

In acidic aqueous media, feldspar minerals can be dissolved to some extents, leading to the formation of secondary pores. Secondary porosity can be quantitatively estimated based on the composition and physicochemical properties of the original and secondary minerals. Secondary porosity formed by dissolution of K-feldspar can be as high as 11.91%, while that of calcium feldspar is the lowest, being only 0.27%, and that of sodium feldspar and andesine range between the former two. Some of the CO (2) needed for dissolving feldspar might have been sourced from meteoric water and/or dissolved from the air when water got in touch with atmospheric air, while the others might have been the products of decomposition of organic matter during generation of hydrocarbons.