南岭花岗岩区锂铍铌钽成矿规律与找矿方向

Metallogenetic regularity and prospecting direction of granite related Li-Be-Nb-Ta deposits in the Nanling region,South China

南岭是全球最重要的稀有和有色金属资源基地之一,以大面积出露的花岗质岩浆岩与大规模的稀有金属矿化而举世瞩目。华南多旋回构造岩浆活动,造就了广泛发育的各类花岗岩,并普遍经历了高分异作用,使得钨、锡、锂、铍、铌、钽等稀有金属不同程度富集成矿。前人对南岭钨和锡的时空分布规律、成矿作用和成矿动力学背景进行了大量研究。本文结合近年矿产调查新进展,重点总结了南岭花岗岩区锂铍铌钽矿化类型、时空分布规律及其成矿条件,系统梳理了锂铍铌钽矿化相关花岗岩的成矿专属性。花岗质岩浆体系中源区组成、部分熔融程度、结晶分异程度、岩浆-热液流体的交代作用控制着锂、铍、铌、钽的分配和富集,铌和钽可在花岗质岩浆熔体演化晚期阶段形成独立矿物,铍一般在岩浆-热液的过渡阶段富集,锂在伟晶岩阶段形成锂辉石,也可富集于流体中交代形成锂云母。南岭地区铌钽矿化主要产出在花岗岩晚期阶段和云英岩中,铍常与钨锡相伴生产出于石英脉型和接触交代型矿床中,南岭锂资源以锂云母形式主要产出于富锂花岗岩体的云英岩化带。本文进一步讨论了多期岩浆作用与铌钽成矿关系、岩浆热液体系中铍与钨锡的成矿机理及南岭花岗岩区锂(锂云母)的成矿潜力,这对下一步南岭地区锂铍铌钽找矿行动部署具有重要的意义。

The Nanling region is one of the world s most essential rare and non-ferrous mineral resource bases,characterized by abundant highly fractionated granitic rocks exposed accompanied with significant rare metal mineralization,including W,Sn,Li,Be,Nb,Ta,which were due to the multiple tectono-magmatic events.The spatial-temporal distribution,mineralization and metallogenic dynamics of W and Sn in the Nanling region have been studied by previous studies.Based on the latest exploration progress in the Nanling region,this paper reviews the mineralization type,temporal and spatial distribution of Li-Be-Nb-Ta deposits and their relationship with highly fractionated granites,and summarize the metallogenic specialization of granites related to Li-Be-Nb-Ta mineralization.The distribution and enrichment of Li,Be,Nb,Ta is controlled by composition of source,partial melting crystallization differentiation and the alternation of magma-hydrothermal fluid in granitic magma system.Nb and Ta generally aggregate in the late stage of magmatic evolution.Be tends to be enriched in the magma-hydrothermal transition stage.Li forms spodumene at the pegmatite stage,and can also be enriched in the hydrothermal fluid metasomatism to form lepidolite.In the Nanling region,Nb-Ta mineralization is mainly hosted in greisens and top of granites.Be and W-Sn mineralization are hosted in quartz-vein type deposits and contact metasomatic type deposits.Li resources are mainly hosted in greisenization zone of Li-rich granites.This paper further discusses the relationship between multi-stage magmatic activities and Nb-Ta mineralization,the mineralization mechanism of Be and W-Sn in magmatic-hydrothermal system,and the potential of Li mineralization in Nanling region,which is of great significance for the Li-Be-Nb-Ta prospecting in this region.