Performing process-oriented investigations involving mass transfer using Rcrust: a new phase equilibrium modelling tool
Published:April 21, 2020
Matthew Jason Mayne, Gary Stevens, Jean-François Moyen, Tim Johnson, 2020. "Performing process-oriented investigations involving mass transfer using Rcrust: a new phase equilibrium modelling tool", Post-Archean Granitic Rocks: Petrogenetic Processes and Tectonic Environments, V. Janoušek, B. Bonin, W. J. Collins, F. Farina, P. Bowden
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Modern quantitative phase equilibria modelling allows the calculation of the stable phase assemblage of a rock system given its pressure, temperature and bulk composition. A new software tool (Rcrust) has been developed that allows the modelling of points in pressure–temperature–bulk composition space in which bulk compositional changes can be passed from point to point as the system evolves. This new methodology enables quantitative process-oriented investigation of the evolution of rocks. Procedures are outlined here for using this tool to model: (1) the control of the water content of a subsolidus system based on available pore space; (2) the triggering of melt loss events when a critical melt volume threshold is exceeded, while allowing a portion of melt retention; (3) the entrainment of crystals during segregation and ascent of granitic magmas from its source; (4) the modification of the composition of granite magmas owing to fractional crystallization; and (5) the progressive availability (through dissolution) of slow diffusing species and their control of the effective bulk composition of a system. These cases collectively illustrate thermodynamically constrained methods for modelling systems that involve mass transfer.
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Post-Archean Granitic Rocks: Petrogenetic Processes and Tectonic Environments
CONTAINS OPEN ACCESS
Granites (sensu lato) represent the dominant rock-type forming the upper–middle continental crust but their origin remains a matter of long-standing controversy. The granites may result from fractionation of mantle-derived basaltic magmas, or partial melting of different crustal protoliths at contrasting P–T conditions, either water-fluxed or fluid-absent. Consequently, many different mechanisms have been proposed to explain the compositional variability of granites ranging from whole igneous suites down to mineral scale. This book presents an overview of the state of the art, and envisages future avenues towards a better understanding of granite petrogenesis. The volume focuses on the following topics:
compositional variability of granitic rocks generated in contrasting geodynamic settings during the Proterozoic to Phanerozoic Periods;
main permissible mechanisms producing subduction-related granites;
crustal anatexis of different protoliths and the role of water in granite petrogenesis; and
new theoretical and analytical tools available for modelling whole-rock geochemistry in order to decipher the sources and evolution of granitic suites.