四川盆地东北部三叠系飞仙关组碳酸盐岩成岩作用和白云岩成因的研究现状和存在问题

四川盆地东北部三叠系飞仙关组是我国重要的天然气储集层，优质储层形成机制直接与碳酸盐岩成岩作用、尤其是白云岩化作用相关，但飞仙关组碳酸盐岩在锰含量、锶含量、阴极发光性等特征上反映其成岩过程与经典成岩理论相悖；碳酸盐岩的锶同位素组成和锰、锶含量的关系也表明与大气水有关的成岩过程和作为重要储集岩的结晶白云岩的形成机制无关，传统的白云岩化机制难以解释结晶白云岩的成因。具有海源色彩的高锶、低锰成岩流体在很大程度上控制了飞仙关组碳酸盐的成岩作用，其来源与成因值得进一步关注，控制其运移、封存和发生水—岩反应的时空机制有待回答。整个海相三叠纪时间段盆地尺度碳酸盐岩和蒸发岩的沉积地球化学研究、尤其是不同结构组分碳酸盐的锶同位素组成、锶和锰含量研究（包括碳酸盐岩中不同结构组分的阴极发光性研究），可为四川盆地东北部飞仙关组碳酸盐岩成岩作用（尤其是白云岩化作用和作为重要储集岩的结晶白云岩的成因研究），天青石矿床成因研究和四川盆地三叠系深层富钾、锶、硼、溴卤水的成因研究提供重要的线索。

The Diagenesis and Dolomitization of the Feixianguan Carbonates of Triassic in NE Sichuan Basin: An Overview

The Feixianguan carbonates of Triassic in NE Sichuan Basin are the most important gas reservoir of China. The forming mechanism of high quality reservoir with higher porosity and permeability is related to diagenesis, especially dolomitization. However , the diagenetic models of Feixianguan carbonates are not consistent with the fundamental principles of carbonate diagenesis in the concentrations of strontium and manganese, and the cathodoluminescence of them. The relationship of strontium isotope compositions and concentrations of strontium and manganese of the carbonates also shows that the diagenetic process of crystalline dolomite, which is the most important gas reservoir, has never been influenced by meteoric fluids. It is difficult to explain the origin of crystalline dolomite by traditional dolomitization mechanisms. The diagenesis of the Feixianguan carbonates should be governed by some kinds of marine fluids rich in strontium and poor in manganese. It is valuable to pay further attention to the source and origin of the trapped marine fluids during the diagenesis. The spatio-temporal factors controlling the migration, trapping and water-rock interaction of the fluid are still waiting to be answered. The geochemical study for carbonates and evaporites, especially the strontium isotope composition and concentrations of strontium and manga- nese, including cathodoluminescence of the carbonates with various fabrics for marine Triassic, in basin scale, will provide an important clue to the origin of the crystalline dolomite as the important gas reservoir.