Research advances on rare metal pegmatite deposits

Abstract

The pegmatite deposit is one of the most important types of rare metal deposits in the world, and it is also one of the most popular interests in the international deposit research.Significant advances have been made in the latest decades, including the classification, source of ore-forming fluids and materials, pegmatite diagenesis mode and enrichment mechanism of rare metals.Ore-related pegmatites have closely temporal-spatial relationship with parental magmatism in general.However, some pegmatites do not show this relative genetic relationship.Studies indicate that the ore-forming melts/fluids of rare-metal pegmatite deposits have properties such as low viscosity, rich water, high dispersibility, and rich alkali, leading to extreme enrichment of elements such as P, F, and B in pegmatite, which migrates and enriches together with rare metals in various complexes or compounds.Li-Cs-Ta type (LCT) pegmatites are closely related to S-type granites.The ore-forming materials are mainly originated from marine sediments like black shale, whereas Nb-Y-F type (NYF) pegmatites are generally associated with A-type granites, which are all derived from the same magmatism.Granitic magma fractional crystallisation and partial melting of crustal or mantle-derived rocks are the two significant formation modes of pegmatites.Meanwhile, three enrichment mechanisms, including fluid immiscibility, highly crystalline differentiation of the flux-rich granite slurry and hydrothermal metasomatism, are widely used to interpret the formation of rare metal pegmatite deposits.

Keywords

• pegmatite
• rare metal deposit
• diagenesis mode
• enrichment mechanism