US-United Kingdom Cooperative Research: The Role of Boron in the Magma-Vapor Evolution of Granitic Systems in Cornwalland Devon, England

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This award will support collaborative research between Dr. David London, University of Oklahoma and Drs. D. A. Manning and C.M. Henderson, Department of Geology, University of Manchester, England. The joint study will focus on 1) the magmatic to hydrothermal transition in the Cornish granite systems, 2) the roles of boron and fluorine in melt-vapor evolution and metal transport and deposition, and (3) general modeling of the relations between shallowly emplaced granite/greisen sytems (e.g., Cornwall) and deeper granite/pegmatite equivalents. The granites and associated pegmatites, aplites, and Sn-Cu mineralized greisens of Cornwall and Devonshire, southwest England, are recognized as a global type of differentiated silicic magmatism and associated hydrothermal mineralization. The late-stage evolution of these granites, in particular the temporal and compositional aspects of melt-vapor equilibria, represent a critically important stage of magmatism from both scientific and economic perspectives. Among the volatile or fluxing components in the Cornish granite systems, the role of boron may be the most important and least understood. The proposed work will document the abundance and geologic associations of boron (as tourmaline) in this environment, and the tourmaline will be studied for fluid inclusions that may uniquely reveal the compositions and physical states of fluids generated in the granites and associated veins and host rocks. The results of this study will then be integrated with experimental and theoretical models developed by the principal investigator to elucidate further the geochemical cycle of boron.