The Degree of Undercooling and Critical Metal Mineralization Potential of Granitic Pegmatites

摘要: The geological processes that generate granitic pegmatites also concentrate critical metals (eg, Li, Be, Ta) that are considered strategic as a result of their use in modern, military, and green technology, and supply restrictions related to social, political, technological, and economic issues. However, the petrologic processes that allow for the concentration of these metals to economic abundances in granitic pegmatites remain poorly understood. Undercooling, or crystallization below the liquidus, can experimentally cause saturation in critical metals at much lower concentrations than in more typical (ie non-undercooled) haplogranite systems at 700 C-750 C, a process that theoretically can explain the formation of pegmatites enriched in critical metals. However, undercooling is difficult to demonstrate in natural systems and has primarily been identified by textural observations such as unidirectional growth textures and …