歧口凹陷沙一下亚段湖相白云岩岩石学特征及成因分析

 歧口凹陷沙一下亚段白云岩发育在整体湖扩背景下，通过对研究区白云岩镜下鉴定，扫描电镜分析，发现研究区主要发育泥晶白云岩、微晶白云岩、砂质白云岩、灰质白云岩、泥质白云岩5种。结合阴极发光特征、氧同位素、稀土元素实验，揭示了研究区白云岩化作用的2种成因环境：准同生期的回流渗透白云岩化作用、成岩期的埋藏白云岩化作用。通常准同生期的回流渗透白云岩经过深部热液流体的改造，进而发生埋藏白云岩化作用，多见于裂缝发育区。研究区不同地区发育的不同成因的白云岩，对这些白云岩形成类型和形成环境的研究，以及对下一步预测白云岩储层具有重要地质意义。

Research on Petrologic Character and Genetic Mode of Lacustrine Dolomit

The dolomite of the Sha 1 lower submember in Qikou Sag developed under the background of lake expansion. Through microscopic identification and scanning electron microscopy analysis on the dolomite samples in the studied area, it is shown that there are 5 types of dolomites developed in the area, i.e., microcrystalline dolomite, micritic dolomite, argillaceous dolomite, sandy dolomite and calcite dolomite or dolomite limestone. The cathodoluminescence, oxygen isotope and rare earth element analysis reveals two environment causes of the dolomitization: the return of penecontemporaneous penetration of dolomitization and burial diagenetic dolomitization.,Burial dolomitization on the back penecontemporaneous dolomite infiltration usually occurs at the fracture well-developed zone, through the transformation of the deep hydrothermal fluid. Different origins of dolomite developed in different regions in the studied area. These types of dolomite formation and the study on formation of environment greatly promote the dolomite reservoir prediction.