海绿石成因类型及其对沉积环境的指相分析

The Genetic Types of Glauconite and the Relationship Analysis of Facies and Sedimentary Environment

海绿石不仅可以作为地层对比的标志矿物,而且可以作为指相矿物反映沉积环境,它包含了丰富的地质信息。通过对海绿石形成条件及成因类型划分进行再认识,对其不同划分类型与沉积环境关系进行分析,认为对海绿石成因类型划分理论主要有两种:溶液胶体沉积理论和海绿石化作用理论。在这两种理论基础上提出的淀胶沉积及粘土矿物交代理论等,均反映了海绿石化学成因类型的本质,为以颗粒状、团粒状、碎屑胶结物、孔隙充填等多种产出形态的海绿石从成因上提供依据。基于成因分析,根据海绿石搬运与否、产出形态以及成熟度类型的综合分析,利用显微镜观测,扫描电镜、电子探针、X衍射分析、红外光谱分析、拉曼光谱等方法对海绿石类型进行辅助确定,认为原地自生海绿石能作为指相矿物,反映沉积环境,原地次生、异地自生及异地次生海绿石均无法作为沉积环境的直接指相证据,但仍可以反映沉积古水流及沉积环境能量信息,为综合确定沉积环境提供依据。

Glauconite can not only be regarded as index mineral of stratigraphic correlation, but also be used as diagnostic minerals of sedimentary environment, which contains abundant geological information. Through the recognition of the formation conditions and genetic types of glauconite, the relationship between the different sediments and the sedimentary environment is summarized, two main views of genetic types division of glauconite can be concluded: solution colloid deposition theory and glauconitization effect theory. Starch adhesive deposition theory and clay mineral metasomatic theory are based on these two theories, both of them can reflect the essence of glauconite chemical genetic type, which can provide evidence for the glauconite with various output forms of granular, crumb, clastic cement and pore filling. Based on the analysis of the causes, carrying, output forms, maturity type, using microscope, scanning electron microscope, electron probe, X diffraction analysis, infrared spectroscopy, Raman spectroscopy and other methods, the type of glauconite can be auxiliarily determined. The option is thought to be right that autochthonous glauconite can be used as facies mineral to reflect sedimentary environment. These kinds of glauconite cannot be directly used as the sedimentary environment evidence such as autochthonous secondary, allochthonous, allopatry, which can still reflect the information of paleocurrent and sedimentary information to provide the comprehensive basis of sedimentary environment.