内蒙古巴音戈壁盆地塔木素地区砂岩型铀矿控制因素与成矿模式

Ore-Controlling Factors and Metallogenic Model of Tamusu Sandstone Type Uranium Deposit in Bayingobi Basin,Inner Mongolia

巴音戈壁盆地塔木素地区位于哈萨克斯坦、西北利亚、塔里木、中朝四大板块的拼合部位,砂岩型铀矿成矿构造背景、矿体形态和目的层岩石学特征独特。以野外岩心观察、钻孔对比分析、镜下微观研究和同位素分析测试等为手段,从构造、铀源、古气候、沉积砂体特征和氧化流体活动等方面分析了矿床的成矿控制条件,认为丰富的铀源、含矿层形成后的构造反转、辫状三角洲前缘互连通砂体、古气候转变和层间氧化带的发育等为砂岩型铀矿的成矿提供了有利的条件,后期热液活动促使铀矿化的富集。根据矿体形态与空间分布、矿石组成成分等特征探讨了矿床成因,并在此基础上初步总结了成矿模式,认为塔木素地区铀成矿以层间氧化作用为主,后期热液改造叠加使矿化进一步富集;同时推断在南部层间氧化带尖灭的地方,应该存在富大矿体。

Bayingobi Basin Tamusu sandstone type uranium deposit, located in the four major plate collision area, is unique in tectonic background, ore body shape and petrological characteristics of target layer. In this paper, we analyzed the metallogenic controlling conditions by aspects of the structure, uranium source, paleoclimate, sedimentary sand body characteristics and oxidation fluid activities. We took the means of observation core in field, comparative analysis of drilling, research under the microscope, isotope test and analysis and others. It was concluded that the rich uranium sources, tectonic inversion after the formation of target layer, good connectivity of braided deha sand, inversion of paleoclimate and interlayer oxidation zone were favorable conditions for the mineralization of sandstone type uranium. Thermal activi- ty occurred later made the uranium mineralization enrichment. According to the distribution, shape of ore body and the composition of ore, we discussed the formation of Tamusu deposit, and on this basis, sum- marized a preliminary metallogenic model. The uranium mineralization in Tamusu was mainly controlled by interlayer oxidation, and later hydrothermal fluid superposition made the uranium further enrichment. It is also thought that at the southern part of the oxidation zone disappeared, across the fault, there should ex- ist rich ore body.