松辽盆地白垩系砂岩成岩作用

DIAGENESIS OF CRETACEOUS SANDSTONE IN SONGLIAO BASIN

通过研究砂岩的自生矿物、也隙变化特征及石英和长石的次生生长,认为 SiO_2的主要来源是由于长石溶解和粘土矿物的转化。斜长石的钠长石化可在较低温度、压力的浅层发生,而钾长石的钠长石化则是在较深层段进行。文章还讨论了自生方解石、浊沸石和粘土矿物的分布、成因及压实、胶结和溶解作用对砂岩孔隙的影响。次生孔隙主要是长石、岩屑溶解的结果。斜长石溶解开始开成岩早期,钾长石溶解一般发生在成岩晚期。

Autogeneous minerals, change of sandstone porosity and secondary overgrowth of quartz and feldspar was mainly discussed in the paper. It was suggested that the dissolution of feldspar and tramsformation of clay minerals (kaolinite to illite) are important source for silica. Albitization of plagioclase could occur under the conditions of low t and low p and of K-feldspar in a more deeper part. Origin and distribution of calcite, laumontite and clay ,min-erals were also discussed. Compaction, cementation and dissolution are all important factors which can affect the change of sandstone porosity. Secondary pores result mainly from the dissolution of feldspar and rocd fragments, and the dissolution of plagioclase occur in early diagenesis and of K -feldspars in late diagenesis.