巴音戈壁盆地塔木素铀矿床碳酸盐胶结物特征、成因及与铀成矿的关系OA

Tamusu deposit is a very large sandstone uranium deposit in produced in Bayingobi Basin with large scale of oxidation zone and obvious hydrothermal alteration,etc.and the wide distribution of a large number of carbonate cement such as dolomite and iron dolomite in the target layer with the characteristics of multi-phase,multi-causes.Therefore,the analysis of the carbonate cement type,genesis and evolution process is of great indicative significance in revealing the action mode and types of the fluid and its role in uranium mineralization.In this paper,the petrographic and geochemical characterization of carbonate cement of sandstone in Tamusu uranium deposit was studied to identify the evolutionary sequence,invert the process of fluid action,and discus the main controlling conditions and deposit genesis by quantitatively analyzing the major elements.The results show that the carbonate cement of Tamusu uranium deposit mainly consists of four types,namely,calcite,dolomite,ankerite and siderite,which distribute in obvious zonation.the oxidized zone is dominated by microcrystalline dolomite and siderite,the grey mineralized zone is dominated by ankerite and coarse-grained authomorphic dolomite,the purplish-red U-P mineralized zone is dominated by microcrystalline dolomite,and the reduced zone is dominated by dolomite and calcite.Among them,mud crystal calcite and siderite were of sedimentary origin,microcrystalline dolomite was formed by hot-water deposition,the formation of ankerite was related to hydrothermal events and multi-phase secondary oxidizing fluid interactions,and uranium minerals were mainly deposited in the ankerite growth rings and dissolution holes,and coexist with close pyrite.