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纳岭沟铀矿床位于鄂尔多斯盆地东北部的伊陕单斜构造区,该区含矿主岩为中侏罗统直罗组下段下亚段。本文通过电子探针、能谱及背散射分析等方法,详细研究了该区目的层砂岩的铀矿物类型及其赋存形式,并对其矿物组合特征及期次等进行了探讨。结果表明纳岭沟地区铀矿物主要为铀石,还有少量的含钛含铀矿物、沥青铀矿、铀钍石等。铀矿物与黄铁矿、蚀变钛铁矿、锐钛矿/白钛石、粘土矿物等密切共生,呈毛刺状或微细柱状产于矿物边缘,或呈粒状产于黑云母解理缝中,另外也见产于碎屑颗粒中。结合电子探针及背散射分析,对蚀变黑云母解理缝中黄铁矿及铀石成因、以及蚀变钛铁矿与铀特殊关系进行了初步探讨。另外该区存在高Y和低Y元素两种铀石类型,沥青铀矿可能为原铀矿物蚀变残留,结合矿物蚀变期次,初步认为该区含铀砂岩至少遭受两期不同成矿流体作用,多源流体耦合成矿可能是砂岩型铀成矿的重要机制之一。
The Nalangougou uranium deposit is located in the Yi-Shan monoclinic tectonic zone in the northeastern Ordos Basin. The ore-bearing host rock in this area is the lower sub-member of the Lower Jurassic Zhiluo Formation. In this paper, by means of electron probe, energy spectrum and backscattering analysis, the types of uranium minerals and their occurrences in sandstones are studied in detail. The characteristics of mineral assemblages and the times and so on are also discussed. The results show that the main mineralized uranium minerals in the Nalinogou area are small amounts of titanium-bearing uranium minerals, asphaltic uranium deposits, uranium, thorium and so on. Uranium minerals and pyrite, alteration ilmenite, anatase / white titanium stone, clay minerals closely intergrowth, was burr-shaped or fine columnar produced in the edge of the mineral, or was produced in granular mica cleavage seams, See also produced in the debris particles. Combined with the electronic probe and backscattering analysis, the genetic relationship between pyrite and uranium in the cleavage seams of altered biotite and the special relationship between alteration of ilmenite and uranium was discussed. In addition, there are two types of uranium rocks with high Y and low Y elements in the area. Asphaltic uranium deposits may be remnant of original uranium minerals. Combined with alteration of mineralization, it is preliminarily believed that the uranium-bearing sandstone has suffered at least two stages of ore-forming fluids The role of multi-source fluid coupling mineralization may be one of the important mechanisms of sandstone-type uranium mineralization.