白云石形成过程中的热力学与动力学基础及白云岩形成环境划分

CaMg(CO3)2在现代海水中是过饱和的,但是前人的研究发现在实验室标准状态下(25℃,1atm)无法从海水中直接沉淀出白云石,所以,白云石的形成不是一个单纯的热力学问题,而是一个动力学问题。依据白云石形成的热力学和动力学特征,将白云岩的形成环境划分为表生成岩环境与埋藏成岩环境。表生成岩环境按白云岩发育位置又分为:潮坪-澙湖蒸发环境、环礁潜流面与深?粱肪场B癫爻裳腋萘魈褰胩逑?的方式又分为:与裂缝相关的埋藏成岩、与缝合线相关的埋藏成岩、与岩溶相关的埋藏成岩和与渗透回流相关的浅埋藏成岩。分别对所划分的各成岩环境进行了详细的岩石学与地球化学特征分析与讨论。

Thermodynamic and Kinetic Principle in Dolomitizition Process and the Division of Dolomistone Diagenetic Environment

Based on dissolve-precipitate thermodynamic principle, CaMg(CO3)2 is supersaturated in present-day sea- water. Previous studies have shown that dolomite can not be directly precipitated from seawater under standard ex- perimental conditions (25℃,1atm) so that it is suggested that dolomite formation should not only be related to thermo- dynamic factor but also kinetic factor. The authors studied thermodynamic and kinetic principles in dolostone genesis and discussed the possible factors overcoming the kinetic barrier during the dolomitizition process.Because of the complicated genesis of dolostone, we can not apply the sedimentary facies to study dolostone. The "Sedimentary dia- genesis facies" were firstly inducted, which means the geological settings of sedimentary of diagenesis for dolostone. Integrating the international dolomitic models,we divided the sedimentary diagenesis facies into surface sedimentary facies and burial diagenesis facies, which are divided in detail and the possible lithologic and geochemical characteris- tics of dolostone for each facies were discussed.