Rare metal deposits in South China: Types, characteristics, distribution and tectonic setting

华南地区是我国重要的战略矿产资源基地，以发育大规模多时代、多旋回花岗岩和独特的中生代铜钼钨锡铌钽铍铀等大规模稀有金属和有色金属成矿作用而闻名于世。华南地区稀有金属（W-Sn-Nb-Ta-Li-Be）成矿作用主要与高度分异演化的花岗岩密切相关。稀有金属矿床的分布受区域性断裂控制，主要集中于南岭地区和钦-杭大断裂两侧。成矿类型主要有花岗岩型、伟晶岩型、云英岩型、石英脉型、火山岩型、接触交代岩型（包括矽卡岩型和条纹岩型）。花岗岩型稀有金属矿床主要沿钦-杭大断裂两侧分布；伟晶岩型矿床主要分布在钦-杭大断裂花岗岩型矿床的外侧，以及邵武-河源断裂和政和-大埔断裂之间；接触交代型（含条纹岩型）稀有金属主要呈东西向分布于南岭地区，石英脉型和云英岩型稀有金属矿床主要与该地区的石英脉型钨矿有成因联系；火山岩型稀有金属矿床主要分布于政和-大埔断裂以东的东南沿海火山岩地区。华南稀有金属成矿可以分为7个阶段，分别是志留纪（424~420Ma）、早三叠世（248~244Ma）、晚三叠世（220~214Ma）、晚侏罗世（160~150Ma）、晚侏罗世-早白垩世（150~140Ma）、早白垩世（135~125Ma）和早白垩世-晚白垩世（105~90Ma）等。在每个时间段内，成矿时间相对集中。大规模稀有金属成矿主要集中于早白垩世。在不同成矿尺度，稀有金属矿化具有明显金属分带特征，且与有色金属矿化具有明显的成因关系；不同金属组合的稀有金属矿床具有不同的岩浆热液演化历史。地壳物质的部分熔融、持续能量供给，以及有利于岩浆高度分异演化的大型伸展构造是形成稀有金属矿床的重要条件。本文认为早白垩世（135~125Ma）是华南地区稀有金属大规模成矿的时期，该时期不仅成矿强度大，而且成矿类型多样，代表了华南中生代岩石圈大规模减薄或者全面裂解的峰期。;South China is an important strategic mineral resource base in China. It is famous for the occurrences of multi-stages granite and related large scale Mesozoic Cu-Mo-W-Sn-Nb-Ta-Be-REE mineralization. The mineralization of rare metals (W-Sn-Nb-Ta-Be) in the area is closely related to highly differentiated granites, and is obviously controlled by regional faults. The distribution of rare metal deposits in South China is mainly concentrated in Nanling area and the close to and the both sides of the Qin-Hang fault. The main metallogenic types are composed of granite-type, pegmatite-type, quartz-vein-type, volcanic-hosted-type and replacement-type (including the skarn-type and ribbon rock-type). Granite-type deposits are mainly distributed along both sides of Qin-Hang fault; Pegmatite-deposits are mainly distributed outside of Qin-Hang fault as well as between Shaowu-Heyuan fault and Zhenghe-Dapu fault; The replacement-type deposits are mainly distributed in the Nanling area in the east-west direction, while the quartz-vein-type deposits are genetically related to the quartz-vein type tungsten deposits in Nanling; The volcanic-hosted-type deposits are mainly distributed in the southeastern coastal volcanic area to the east of Zhenghe-Dapu fault. The metallogenic epoch of the rare metal deposits in South China can be divided into seven periods: Silurian (424~420Ma), Early Triassic (248~244Ma), Late Triassic (220~214Ma), Later Jurassic (160~150Ma), Late Jurassic-Early Cretaceous (150~140Ma), Early Cretaceous (135~125Ma) and Early Cretaceous-Late Cretaceous (105~90Ma). They are quite difference in the metallogenic intensity and the metallogenic scale. However, the large-scale mineralization is mainly concentrated in the Early Cretaceous. On the ore field scale, rare metal mineralization has obvious metal zoning, and has experienced obvious genetic relationship with non-ferrous metal mineralization; Rare metal deposits with different metal assemblages have different longer magmatic-hydrothermal evolution history. Partial melting of crustal materials, continuous energy supply and large-scale extension favorable for magma differentiation and evolution, they are the key factors for the formation of large-scale rare metal deposits. The paper concluded that the Early Cretaceous (135~125Ma) is a key period for large-scale rare metals mineralization in South China, which not only has the highest intensity of mineralization, but also has various types of mineralization, representing the peak period of large-scale thinning or disintegration of the continental lithosphere in Mesozoic in South China.