Alteration Products of Beryl as Indicators for the Evolution of Rare Metal Pegmatites
Fields of Study: Igneous Petrology, Mineralogy, Critical Metals
Support Offered: Analytical Costs
Pegmatites often host economic concentrations of incompatible ‘critical metals’ like Li, Be, Rb, Nb, Ta, Sn and the REEs. However, the susceptibilities of pegmatites to hydrothermal overprinting make them complex and challenging to decipher in terms of their magmatic and hydrothermal evolution and how these influence ore deposit and exploration models. This project will conduct detailed analysis (i.e., via SEM/EDS, EPMA, LA-ICP-MS and Raman spectroscopy) of beryl phenocrysts sampled from pegmatites of the Mt. Isa inlier. These beryls are unusual in that they are: 1) heavily altered by magmatic and meteoric fluids; 2) replaced by a wide array of secondary Be-bearing and Be-barren minerals; 3) highly variable in composition, despite existing within the same outcrop, and; 4) hosts of circular granitic ‘cores’ of quartz, feldspar, tourmaline and mica. Their detailed textural and geochemical analysis is thus expected to provide new information as to how the pegmatites at Mt. Isa were emplaced and altered, which can in turn be used to help elucidate the complex histories of rare metal-bearing pegmatites globally in such a way that significantly furthers critical metal exploration.
Experimental Alteration Products of Beryl as Indicators for the Evolution of Rare Metal Pegmatites
Fields of Study: Igneous Petrology, Mineralogy, Critical Metals
Support Offered: Analytical Costs
Pegmatites often host economic concentrations of incompatible ‘critical metals’ like Li, Be, Rb, Nb, Ta, Sn and the REEs. However, the susceptibilities of pegmatites to hydrothermal overprinting make them complex and challenging to decipher in terms of their magmatic and hydrothermal evolution and how these influence ore deposit and exploration models. This project will involve the experimental hydrothermal alteration of gem-quality beryl – a common phase in pegmatitic ores – under laboratory conditions, prior to the detailed characterisation of experimental products (both solids and fluids) by XRD, SEM/EDS, EPMA and (LA)-ICP-MS. Reaction conditions will be selected by the student based on a thorough review of the relevant natural conditions in pegmatites, and the unique mineralogical products of each reaction will be related back to natural examples to draw conclusions as to the likely physiochemical nature of geological fluids which generate the various beryl alteration assemblages that are observed in nature. This in turn will help to improve interpretations of natural beryl alteration assemblages, by allowing them to be related to specific fluid types that will then inform the nature of pegmatite emplacement and evolution.
