稳定碳、氧同位素地球化学特征与成岩环境分析——以川东北地区上二叠统长兴组白云岩为例

The Geochemical Characteristics of Stable Carbon and Oxygen Isotope and Analysis of Diagenetic Environment——A Case Study of Upper Permian Changxing Formation Dolostone in Northeast of Sichuan

摘要: 四川盆地东北部上二叠统长兴组白云岩为重要的优质储层，近年来，长兴组白云岩成岩环境或成因问题成为研究者讨论的热点话题。在岩石学研究的基础上，运用稳定碳、氧同位素，对研究区长兴组白云岩进行综合研究表明，白云石化具有多期次的特点，按照成岩环境划分为蒸发环境下的准同生白云岩和埋藏条件下的早、中、晚期成岩白云岩。并划分为早、中、晚成岩阶段，结合碳、氧同位素分析结果进一步表明晚成岩阶段白云岩是构造热液白云石化的结果。

Abstract: The dolostones in Changxing Formation of the Upper Permian in the northeastern Sichuan Basin is an important high quality reservoir. In recent years, the diagenetic environment or cause of dolostones in Changxing Formation has become a hot topic for researchers to discuss. Based on the analysis of petrology and stable isotopes of carbon and oxygen, this paper comprehensively studies the formation mechanism of dolostone of Changxing Formation. The results of study show that dolomitization has muti-period characteristic. According to the analyses of diagenetic environment, the dolostones have been divided into penecontemporaneous dolostone related to evaporation environment and the early, middle and late diagenetic dolostone in the burial environment. The diagenetic stages have been further divided into early, middle and late diagenetic stage. Combined with analysis results of carbon and oxygen isotope, it indicates that the late diagenetic stage dolostone is the result of hydrothermal dolomitization.