湖相碳酸盐岩白云石化流体来源、作用机制及物质过程

Source of dolomitization fluid,mechanism and material process of lacustrine carbonate rocks

湖相白云岩具有重要的油气地质意义,广泛发育于我国东部新生代地层中。本文通过大量资料统计和分析前人对国内湖相白云岩的研究成果,系统阐述了国内主要湖盆的湖相白云岩的成因、形成流体来源及相关物质的响应。根据白云石化流体的碳氧同位素、锶钡比、有序度、pH值、Eu异常、Ce异常等各类指标,将白云石化流体分为原始湖泊、外来淡水、热水热液和海源流体等类型。不同类型流体来源改造下生成白云岩所伴生的矿物组合不同;不同白云石化流体通过微生物作用、准同生作用、热液作用和埋藏作用等方式对原始碳酸盐岩进行白云石化作用,不同白云石化作用机制直接制约了其物质响应过程。提出了未来利用定量分析技术深入开展白云石化流体来源分析、准确判断成岩流体类型或成岩作用机制是进一步研究的方向。

Lacustrine dolomite is geologically important to petroleum.It is widely developed in eastern China in the Cenozoic strata.Based on statistics and analysis of a large number of research results of domestic lacustrine dolomite is expounded genesis of the main lacustrine dolomite formations in China and source of dolomitization fluid and related material response.According to carbon and oxygen isotopes,Sr/Ba ratio,order degree,pH value,anomaly of Eu and Ce the dolomitization fluid is sourced from the original lake,foreign freshwater,hydrothermal and marine fluid respectively.Dolomites are varied with different mineral assemblages means that they are formed by reworking of different soured fluids.Under microbial interaction,quasi syngenetic action,hydrothermal action and burial the original carbonate rocks are dolomitized and the mechanism of dolomitization estricts directly the process of material response.Finally,the future quantitative analysis technology should be used to further analyze the source of dolomitization fluid,and to determine the type of diagenetic fluid or the mechanism of diagenesis accurately.