江西硬岩型锂矿类型划分及其找矿启示
Classification of hard rock lithium deposits in Jiangxi Province and its implication for prospecting
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摘要: 近年来,江西硬岩型锂矿取得重大找矿突破,赣东北地区横峰松树岗探明超大型铌钽矿,伴生氧化锂资源量达超大型,赣西地区新探明巨量花岗岩型锂矿资源,赣南地区新发现云英岩型锂矿。为进一步总结区域成矿规律,查明硬岩型锂矿成矿潜力,实现区域锂矿成矿理论创新,从而指导找矿勘查与综合利用,需要科学合理划分江西省硬岩型锂矿的矿床类型,建立区域找矿标志。文章在野外地质矿产调查的基础上,综合前人研究成果,将江西硬岩型锂矿划分为蚀变花岗岩型、伟晶岩型、细晶岩(霏细斑岩)型和云英岩型4种矿床类型,并根据成矿地质体特征、蚀变作用类型、赋矿围岩、主要含锂矿物类型及成矿时代等要素细分为9种矿化类型。同时,江西硬岩型锂矿均属于与花岗岩有关的内生矿床,对与锂矿成矿相关的花岗岩基本特征进行了总结。研究表明:蚀变花岗岩型锂矿是江西重要的锂矿资源类型,与成矿相关的淡色花岗岩体是重要的找矿目标地质体;云英岩型锂矿化的发现,为“就钨找锂”理论提供了重要依据,指示在江西乃至华南已知钨多金属矿床外围及深部具有巨大的锂矿找矿潜力。此外,应积极探索利用“以脉找体”的找矿思路,今后要重点加强含W、Sn成矿岩体内外接触带中脉状云英岩及其下部蚀变花岗岩中找锂矿工作,助推锂矿找矿实现新突破。Abstract: In recent years, the exploration of hard rock lithium deposits has made great breakthrough in Jiangxi Province, including the discovery of a super large niobium-tantalum deposit associated with ultra-large scale of lithium oxide resources in Songshugang of Hengfeng County, northeastern Jiangxi, a huge amount of granitic lithium resources in western Jiangxi, and greisen lithium deposits in southern Jiangxi. It's necessary for us to scientifically divide the types of hard rock lithium deposits in Jiangxi and establish local prospecting indicators, by further summarizing regional metallogenic regularity and identifying metallogenic potential, we can innovate the metallogenic theory of regional hard rock lithium and improve ore-prospecting and comprehensive utilization. Based on the field investigation and previous research results, this paper divides the hard rock lithium deposits in Jiangxi into four types:altered granite type, pegmatite type, aplite (felsophyre) type and greisen type, and nine mineralization types in accordance with the characteristics of ore-forming geological bodies, alteration types, ore-bearing surrounding rocks, main lithium-bearing mineral types and metallogenic age. Meanwhile, the hard rock lithium in Jiangxi are all endogenous deposits related to granite. This paper also summarizes the basic characteristics of the granite-associated lithium mineralization. The research shows that the altered granite lithium deposit is an important lithium type in Jiangxi, and the light granite body related to mineralization is an important targeted prospecting geological body. The discovery of greisen lithium mineralization provides an important basis for "looking for lithium in tungsten", indicating great potential for lithium prospecting in the periphery and deep of known tungsten polymetallic deposits in Jiangxi and even South China. In addition, we should actively explore the idea of "looking for orebody after vein". In the future, we should strengthen lithium deposits prospecting in vein-like greisen and its lower altered granite in the inner and outer contact zone of W-Sn metallogenic rock mass, so as to accelerate the breakthrough of lithium ore prospecting.