松辽盆地红岗油田白垩系青山口组发育含片钠铝石砂岩.通过偏光显微镜、扫描电镜、阴极发光仪、X射线衍射等多种技术手段,对含片钠铝石砂岩的碎屑成分、胶结物类型及自生矿物共生序列等特征进行了研究.该区含片钠铝石砂岩为岩屑长石砂岩及长石岩屑砂岩,胶结物有次生加大长石、次生加大石英、自生石英微晶、黏土矿物、片钠铝石、方解石、铁方解石及铁白云石.方解石的形成分为两期,第1期方解石为原始生物碎屑颗粒溶蚀溶解的产物,第2期方解石可能与CO2充注后钙长石及早期碳酸盐矿物的溶蚀溶解有关.含片钠铝石砂岩的自生矿物共生序列为:次生加大长石、早期次生加大石英-自生石英微晶-早期高岭石、第1期方解石、片钠铝石-晚期次生加大石英-晚期高岭石、第2期方解石、铁方解石、铁自云石.其中CO2注入后的矿物共生组合为:片钠铝石-晚期次生加大石英-晚期高岭石、第2期方解石、铁方解石、铁白云石.%Dawsonite (NaAICO3 (OH) 2), as the trace mineral of CO2, is abundant in the Cretaceous Qingshankou Formation of Honggang Oilfield, southern Songliao Basin. Petrologic characteristics including clastic components, cement types and diagenetic mineral association successions of dawsonitebeating sandstones were investigated by polarizing microscope, SEM, X-ray diffraction and CL. This kind of sandstone is mainly debris-feldspar sandstone and feldspathic lithic sandstone, with the cements of feldspar overgrowth ( F2 ), quartz overgrowth ( Q2 ), authigenetic quartz ( Q1 ), clay minerals, dawsonite, calcite, ferron calcite and ankerite. With the help of CL, two stages of calcite were distinguished in the research area, and the early calcite was the product of dissolution of original bioclastic, while the late one was related to dissolution of anorthite and early calcite as the CO2 injecting. The diagenetic association succession for dawsonite-bearing sandstones in the research area are as follows: Feldspar overgrowth, early quartz overgrowth-early kaolinite-authigenetic quartz, Ⅰ calcite, dawsonite-late quartz overgrowth-late kaolinite, Ⅱ calcite, ferron calcite, ankerite and bitumen. Among them, dawsonite,late quartz overgrowth-late kaolinite, Ⅱ calcite, ferron calcite and ankerite are the co-existing combination which were formed after CO2 injection.
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