江西宁都白云母伟晶花岗岩型高纯石英用硅质原料矿床特征与资源潜力

Deposit characteristics and potential resources of silicon material for high-purity quartz of muscovite-pegmatite-granite type in Ningdu,Jiangxi Province

高纯石英以优异的物理化学性能成为战略性新兴产业的关键基础原料,中国是高纯石英消费大国,高端产品全部依赖进口。在高端高纯石英领域,中国面临着优质高纯石英用硅质原料匮乏和高端产品提纯技术短板,优质资源是提纯加工高端高纯石英的关键基础,中国迫切需要突破优质资源瓶颈。通过与美国Spruce Pine白岗岩高纯石英用硅质原料矿床对比研究,在武夷山隆起西部的江西宁都地区发现了白云母伟晶花岗岩型高纯石英用硅质原料,认为西武夷山地区是花岗岩型高纯石英用硅质原料找矿有利地区。本次在成矿地质背景和矿床地质特征基础上,开展矿石矿物特征、石英内部包裹体特征、气液包裹体成分、岩石地球化学、石英杂质元素、主要晶格杂质等研究,探讨矿床成因,评价资源潜力。宁都白云母伟晶花岗岩为亚碱性过铝质花岗岩,富含钾长石,K含量大于Na,具有较高的大离子亲石元素,较低的高场强元素和稀土元素含量,Eu既有正异常也有负异常。石英包裹体以气液为主,气液包裹体面积占比1.69%,含少量白云母等矿物包裹体,主要杂质元素Mg、Fe、Li与Spruce Pine白岗岩石英相近,杂质元素总量低,平均618.03×10^(-6)。石英主要晶格杂质Al、Li、Ti元素总量低,为89.82×10^(-6),石英纯度达到SiO_(2)99.99%以上,是优质高纯石英矿物原料,预测资源规模为大型。宁都白云母伟晶花岗岩赋存于会同岩体中深根部带,为加里东期“S”型花岗岩,由伴随会同岩体同期演化的富含长英质的浅色熔体演化成岩。研究成果对西武夷地区寻找同类型矿床具有典型矿床对比意义,调查评价方法对中国同类型高纯石英用硅质原料找矿具有指导意义。

High−purity quartz,exhibiting exceptional physical and chemical properties,has emerged as a critical raw material for strategic industries.China,being a major consumer of high−purity quartz,currently relies on imports for all its high−end products in this domain.The primary challenges faced by China in the realm of high−end high−purity quartz lie in the scarcity of resources with superior quality silica as raw materials and the dearth of advanced processing technologies.High−quality and high−purity silica are crucial prerequisites for processing high−end,high−purity quartz.Therefore,China urgently needs to break through the bottleneck of high−quality resources.By conducting a comparative analysis with alaskite−type high−purity quartz material from the Spruce Pine region in the USA,we have discovered siliceous materials suitable for producing high−purity quartz in the Ningdu County of Jiangxi Province,located west of the Wuyi Mountains.Consequently,it can be inferred that prospecting in this region offers favorable conditions for obtaining granitic siliceous materials required for manufacturing high−purity quartz.Based on the study of metallogenic geological background and deposit geology,mineral characteristics of ores,quartz inclusions,gas−liquid inclusions composition in quartz,rock geochemistry,impurity elements in quartz and major lattice impurity elements were investigated to discuss the ore genesis and evaluate their resource potential.The Ningdu muscovite granitic pegmatite is classified as subalkaline peraluminous granite with a high abundance of K−feldspar.The K content exceeds that of Na,exhibiting enrichment in large ion lithophile elements while displaying low concentrations of high field strength elements and rare earth elements.Additionally,Eu anomalies are observed both positively and negatively.Gas−liquid inclusions are the predominant type of inclusions found in quartz,constituting approximately 1.69%of the total area,with a small number of mineral inclusions such as muscovite present.The impurity elements Mg,Fe,and Li exhibit similarities to Spruce Pine quartz in alaskite,while the overall content of impurity elements is relatively low at an average value of 618.03×10^(-6).Within the quartz lattice structure,Al,Li,and Ti are identified as the main impurity elements with a very low total content(89.82×10^(-6)),whereas SiO_(2) accounts for over 99.99%of quartz composition.This high−purity silicon material possesses excellent quality and exhibits significant potential as indicated by its abundant predicted resource quantity.Ningdu muscovite granitic pegmatite is situated within the middle−deep root zone of Huitong pluton and represents an S−type granite within the Caledonian orogenic belt that evolved from light−colored granitic magma enriched with feldspar and quartz during the same period as pluton’s evolution process.These research findings hold great significance for comparative studies on similar ore deposits within western Wuyi region,and provide valuable guidance for prospecting activities targeting high−purity quartz silicon materials across China.