文献类型：期刊文献

中文题名：宣威—威宁地区铌矿床的元素赋存状态及富集机制

英文题名：Nb occurrence and enrichment mechanism of niobium deposit at the Xuanwei Formation in Xuanwei-Weining area

作者：杜胜江 温汉捷 罗重光 凌坤跃

第一作者：杜胜江

机构：[1]贵州理工学院矿业工程学院,贵州贵阳550003;[2]贵州省地质调查院,贵州贵阳550081;[3]长安大学地球科学与资源学院,陕西西安710054;[4]中国科学院大学地球与行星科学学院,北京100049;[5]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550081

第一机构：贵州理工学院矿业工程学院

年份：2023

卷号：97

期号：4

起止页码：1192-1210

中文期刊名：地质学报

外文期刊名：Acta Geologica Sinica

收录：CSTPCD;;EI(收录号：20232314186881);北大核心:【北大核心2020】；CSCD:【CSCD2023_2024】；

基金：国家自然科学基金项目(编号92162214,41903038,41962005,42072094);国家重点研发计划项目(编号2017YFC0602500)联合资助的成果。

语种：中文

中文关键词：铌;稀有金属;赋存状态;锐钛矿;榍石

外文关键词：niobium;rare metals;occurrence;anatase;titanite

摘要：铌是一种重要的关键金属,因其特殊的超导性、高熔点、耐腐蚀、耐磨等性质被广泛应用于超导材料、航空航天等新兴领域,是现代高科技产业不可或缺的原料。全球铌资源虽然丰富,但分布极度不均,仅巴西的铌资源就占据了约95%。中国铌资源匮乏,消费量却超过了全球总消费量的四分之一,绝大多数铌依赖于进口,“被卡脖子”风险高。近年研究表明,宣威—威宁地区二叠系宣威组底部的古风化壳普遍富含铌、镓、稀土等多种关键金属,其中Nb2O5含量一般为220μg/g、轻稀土氧化物含量为850~5500μg/g、镓含量一般约50μg/g,均达到了风化壳型矿床的工业品位,且铌、稀土、镓的远景资源量分别超过11万t、40万t、2万t,显示出巨大的资源潜力。尽管前人对该类铌矿床的空间展布、元素分布规律等已进行了较深入研究,但铌的赋存状态及富集机制尚存在较大争议,阻碍对成矿机理的深入认识,制约了对成矿规律及找矿方向的把握。基于此,本文围绕铌赋存状态和成矿机制这一主线,以宣威—威宁地区宣威组铌矿床和底部的玄武岩为研究对象,运用粉晶X-射线衍射(XRD)、电子探针(EPMA)等手段对铌矿化黏土岩和底部玄武岩中的铌赋存状态及微区矿物学开展了系统研究,结果显示铌矿床中主要的载铌矿物为锐钛矿。玄武岩中普遍含有一种特殊的富铌钛矿物——榍石,且研究区发现玄武岩中存在富铌榍石风化蚀变为锐钛矿的重要地质现象。因此,表明铌矿床中的富Nb锐钛矿很可能是由玄武岩中的富Nb榍石风化而来,成矿物质主要来自底部玄武岩中榍石,榍石的风化作用可能是铌富集的主要控制因素。
As one of crucial mineral resources,niobium(Nb)is used in superconducting materials and aerospace because of its special superconductivity,high melting point,corrosion resistance,wear resistance.Nb is an absolutely essential ingredient for high-tech industry development.The global niobium mineral resources are rich but not uniformly distributed as highest values(95%)are in Brazil.Although China is poor in niobium resources,the niobium consumption is more than a quarter of total world consumption.The vast majority of the niobium resources depend on import and there is a high risk of“bottlenecks”in China.Recent studies have shown that ore beds of the lower Xuanwei Formation(Late Permian)are highly enriched in Nb_2O_5(220μg/g),LREE(oxides of La-Lu+Y)(850~5500μg/g),and Ga(50μg/g),and have reached industrial grade in the Xuanwei-Weining area.The prospective reserves of niobium(Nb),gallium(Ga)and rare earth elements(REE)respectively exceed 110000 tons,400000 tons,20000 tons.They indicate a potential to discover more resources.Despite spatial distribution and geochemical element distribution of this type of deposit having been intensively studied,the occurrence state,migration and enrichment mechanism of Nb are still unclear limiting a clear understanding of the metallogenic mechanism.Working with Nb deposit of the Xuanwei Formation and basalt located at the bottom,this study aims to reveal the occurrence state and metallogenic mechanism by X-ray powder diffraction(XRD)and Electro-Probe Microanalyzer(EPMA).The results indicate that the main Nb-carrying mineral is anatase.The basalt generally contains a special Nb-rich mineral named titanite in the Xuanwei-Weining area.It was demonstrated that anatase is generally formed by weathering alteration of titanium minerals such as titanite.Meanwhile,some titanite weathered away to become anatase.In this way,Nb may dissolve from titanite during weathering of the titanite-rich basalt and enter into anatase.Titanite,as a major contributor,may control the migration and enrichment mechanism of niobium during the weathering process.