关键词: 白云岩成因类型, 白云岩传统研究方法, Mg同位素, 团簇同位素, 晶体结构, 激光原位U-Pb定年

Abstract: Dolomite reservoirs have huge oil and gas exploration potential, but there are always disputes on the genesis of dolomite, which greatly affects the effective prediction of high-quality dolomite reservoirs. To further push the study of dolomite genesis, the paper systematically reviews the genetic types and traditional research methods of dolomite, as well as the research progress of non-traditional methods involving Mg isotope, clumped isotope, crystal structure and laser in-situ U-Pb dating in the past two decades, and also summarizes the existing problems. At present, there are more than 20 genetic models of dolomite, and the genetic types of dolomite can be essentially divided into primary dolomite and secondary dolomite. Through continuous exploration, the genetic theories of dolomite have been expanded, and also face challenges; among them, the emerging microbial induction theory has provided a more favorable evidence for the genesis of dolomite, and the genetic theory of some secondary metasomatic dolomite has also been expanded and challenged. The traditional analytical methods of basic petrology, cathodoluminescence, major and trace elements, rare earth elements, fluid inclusions, carbon and oxygen isotopes, and strontium isotopes have made great contributions to the exploration of dolomite genesis, laying a foundation for exploring the genesis of dolomite. The rapid development of non-traditional research methods for dolomite genesis provides more useful information for the formation and evolution of dolomite. Mg isotopes can effectively trace the source of Mg-rich fluid and reconstruct the evolution process of dolomite. Clumped isotope thermometry is of great significance for analyzing the diagenetic environment and diagenetic fluid in terms of dolomite diagenetic temperature and recovery of oxygen isotope value of dolomitized fluid. The crystal structure of dolomite has preserved the unique evidence of environment, crystallization, crystal growth and fluid in its formation process, which can be used as an effective means to study the formation environment and formation mechanism of dolomite. The absolute age determined by laser in-situ U-Pb dating is of great value for understanding the diagenesis and evolution of dolomite. However, the formation of dolomite is a multi-stage comprehensive process involving different geological conditions and different periods, and both traditional and non-traditional dolomite research methods have certain advantages and disadvantages. In many cases, it is difficult to explain the genesis of dolomite only using a single genetic model or research method. Therefore, we shall not simply apply or even abuse the genetic model in the study of dolomite genesis, and shall analyze the specific situation, combine the traditional and non-traditional dolomite analysis methods, and comprehensively consider the geological background, fluid properties, sources, dynamic and thermodynamic mechanisms, so as to give a more accurate and reasonable explanation on dolomite genesis. Through a systematic review and analysis of researches on dolomite genesis, it is expected to provide some reference and new enlightenments for the study of dolomite genesis.

Key words: genetic type of dolomite, traditional research method of dolomite, Mg isotope, clumped isotope, crystal structure, laser in-situ U-Pb dating