An overview of the association between lamprophyric intrusions and rare-metal mineralization

Granite-related rare metal districts in orogenic settings are occasionally associated with lamprophyre dikes. We recorded 63 occurrences of lamprophyres in bimodal dike suites of about 200 granite bodies related to rare metal deposits. Most lamprophyres occur in Paleozoic and Mesozoic metallogenic provinces in the northern hemisphere. Lamprophyres which are associated with rare metal deposits are calc-alkaline (kersantites, minettes, spessartites) or more rarely alkaline lamprophyres (camptonites, monchiquites) which occur in the roof zone of complex granitic bodies as pre-granitic, intra-granitic, intra-ore or post-ore dikes. Most lamprophyres are spatially associated with dominant felsic dikes and/or with mafic dikes represented by diorites or diabases. Diorites and lamprophyres occasionally exhibit transitional compositions from one to another. Lamprophyres share common geochemical characteristics of highly evolved granitoids such as enrichment in K and F, increased abundances of Li, Rb, and Cs and enrichment in some HFSE (e.g. Zr, U, Th, Mo, Sn, W). Lamprophyres in rare metal districts testify to accessibility of the upper crust to mantle products at the time of rare metal mineralization and possible influence of mantle melts or mantle-derived fluids in the differentiation of granitic melts in the lower crust.