摘要:纳岭沟铀矿床位于鄂尔多斯盆地东北部伊陕单斜构造区，其成矿主岩为中侏罗统直罗组下段下亚段。通过野外地质调查、岩芯编录，结合岩矿鉴定、X-衍射、电子探针及扫描电镜等方法，详细研究了该区目的层砂岩碎屑组分、结构及矿物蚀变特征，并初步探讨了其物源及源区构造背景、砂岩绿色成因、成岩作用等特征。结果表明纳岭沟地区含铀砂岩类型以长石岩屑砂岩为主，其成分及结构成熟度均较低，成岩作用较弱，表现为弱压实作用、胶结作用、溶蚀作用以及部分重结晶作用。大量在粒表呈薄膜状及粒间充填的绿泥石等粘土矿物是砂岩呈绿色调的主因。物源可能来自于盆地北缘阴山造山带的太古宙—元古宙变质岩系以及显生宙岩浆岩。其蚀变矿物组合及期次为草莓状黄铁矿—自生高岭石—绿泥石薄膜+粒间绿泥石—铀石+细分散/脉状黄铁矿—亮晶方解石—方解石脉，其成岩环境经历了弱酸性—酸性还原—弱酸弱碱/氧化还原过渡阶段—碱性还原阶段，而砂岩型铀矿的形成与氧化还原—酸碱性过渡成岩环境变化密切相关。
关键词: 鄂尔多斯盆地/
砂岩型铀矿/
纳岭沟地区/
岩石学特征/
成岩蚀变作用
Abstract:Nalinggou uranium deposit is located in the Yishan monoclinal structure area of the northeastern Ordos Basin. The upper part of the lower member of Zhiluo Formation of Middle Jurassic is the metallogenic rock. Through the field geological survey, core logging, and combining the methods of the rock-mineral determination, X-diffraction, electron probe, and scanning electron microscope, the characteristics of detrital grain composition, structure, mineral alteration were explained in detail. In the end, some questions about the provenance, tectonic background of source region, formation of green sandstone and the diagenesis were also discussed simply. The results showed that the types of uraniferous sandstone were mainly composed of feldspathic litharenite. Both compositional maturity and textural maturity were poor, the diagenesis was weak, and it exhibited the weak compaction, cementation, dissolution and partial recrystallization. A large number of the thin film shaped chlorites on the particles surface and the intergranular filled chlorites were the major cause why the sandstones displayed green tone. Besides, its provenance was likely to come from the Yinshan Mountains in northern margin of the basin, where developed the Archaean-Proterozoic metamorphic series and Phanerozoic magmatite. The study of alteration mineral assemblage showed that the sequence of mineral formation was the strawberry pyrite, authigenic kaolinite, clay film and intergranular chlorite, coffinite+colloidal pyrite, crystal calcite, calcite vein. And its diagenetic environment experienced respectively the weak reduction phase, acid reduction phase, weak acid/weak alkaline/redox transition phase, and alkaline reduction phase in the end. While uranium enrichment was closely related to the redox and acid-alkali transitional diagenetic environment.
Key words:Ordos Basin/
Sandstone-hosted uranium deposit/
Nalinggou area/
Petrology characteristics/
Diagenetic alteration
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