滇西腾冲地块构造-盆地演化与砂岩型铀矿成矿条件

发布时间：2018-06-25 13:12

本文选题：腾冲地块 + 砂岩型铀矿　；参考：《地质通报》2017年04期

【摘要】：以"煤铀兼探"新思路带动的中国西南地区新一轮砂岩型铀矿勘查,首选滇西腾冲地块新近纪盆地群为突破口。从容矿主岩沉积建造、铀源地质体配置、成矿作用驱动3个方面,总结了腾冲地块构造-盆地演化对铀成矿的影响。在大陆汇聚构造体制下,地块内发育一系列受断裂制约的狭长状断陷盆地和冲积扇、扇三角洲、辫状河、湖泊的复合沉积体系,扇中辫状河道、三角洲前缘席状砂、水下分流河道等是赋铀砂体发育的有利沉积微相。中特提斯洋俯冲碰撞形成的燕山期中酸性花岗岩和经历多期构造变质的高黎贡山群花岗片麻岩、混合花岗岩为区内铀成矿提供了充足的物质来源。而赋矿层同沉积期的新近纪构造运动,以及第四纪以来的地壳差异升降,驱动了产铀盆地内部的潜水氧化和后期叠加的层间氧化成矿过程。基于上述认识,提出当前区内的铀矿勘查应加强沉积微相和岩相古地理研究,建立赋矿有利相带的空间分布模式;同时加强不同蚀源区地质体的铀源能力分析和成矿作用类型的甄别,更准确地锁定潜在铀矿体的定位规律。
[Abstract]:A new round of sandstone-type uranium exploration in southwest China driven by the new idea of "coal and uranium exploration" is the first choice for the Neogene basin group of the Tengchong block in western Yunnan as the breakthrough point. This paper summarizes the influence of tectonic-basin evolution of Tengchong block on uranium mineralization in three aspects: sedimentary formation of main rock of Congrong ore, disposition of uranium source material body and drive of mineralization. Under the continental convergence system, a series of fault-restricted narrow faulted basins and alluvial fans, fan deltas, braided rivers, lakes, braided river channels, delta front matting sand are developed in the block. The underwater distributary channel is a favorable sedimentary microfacies for the development of uranium bearing sandbodies. The intermediate Yanshanian acid granite formed by the subduction collision in the Middle Tethys Ocean and the granitic gneiss of the Gaoligongshan Group which experienced multiple tectonic metamorphism provide sufficient material source for uranium mineralization in the area. The tectonic movement of Neogene in the same sedimentary period and the crustal differential rise and fall since the Quaternary have driven the submersible oxidation in the uranium-producing basin and the superimposed interlayer oxidation process in the later stage. Based on the above understanding, it is suggested that the present uranium exploration in this area should strengthen the study of sedimentary microfacies and lithofacies paleogeography, and establish the spatial distribution model of ore-bearing favorable facies zone. At the same time, the analysis of uranium source capacity and the discrimination of metallogenic types of geological bodies in different etch source areas are strengthened, so as to localize the potential uranium ore bodies more accurately.
【作者单位】：中国地质调查局成都地质调查中心;
【基金】：中国地质调查局项目《西南地区铀矿调查选区及含煤岩系放射性地质环境调查》(编号:DD20160201)
【分类号】：P619.14

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