Leaders and affiliations : Matthew Steele-MacInnis (University of Alberta); Brendan Dyck (Simon Fraser University); Zeinab Azadbakht (University of New Brunswick); Ed Sawyer (UQAC)
Description : The formation, segregation, migration and fate of crustal-derived melts have major impacts on a variety of geologic processes including the petrologic and tectonic evolution of the continents, chemical cycling in orogenic settings, and concentration of lithophile elements such as Sn and W to form ore deposits. These phenomena involve complex coupling of geochemical and physical processes over a wide range of scales – from the micron scale of melt generation at grain boundaries, to the continental scale of collisions and orogeny. To unravel these processes crucial to the evolution of Earth’s crust requires integration of many types of observational data (including field mapping, microtextural analysis, geochemistry and geophysics), experimental results, and numerical modeling. This session focuses on the origins, physical-chemical properties, and geological processes driven by crustal melting and the presence of crustal melts. The session aims to bring together geoscientists with diverse perspectives on crustal melts, including (but not limited to) geochemistry and petrology, tectonics, geophysics and geodynamics, and economic geology. Topics covered in this session include: 1) Melting – the recognition and consequences of wet versus dry melting, fertility of various rock types, and compositions of melts produced; 2) The fluid dynamics (or lack thereof) of anatectic melts – the segregation and movement of melt in and through the crust; 3) Making granitic magmas – from melting reactions, to restite-unmixing, contamination/entrainment of crystals, magma mixing and fractionation; 4) Crustal-derived magmas in ore-forming settings – magmatic and hydrothermal processes leading to concentration of metals, vapor saturation, compositions of fluids produced and circulated, and ore precipitation; 5) Tectonic and geodynamic processes and consequences of partial melting – the reworking of continental crust into its present gravitationally stable, compositionally layered state. The session welcomes contributions that address these topics using approaches including field-based and analytical studies, experiments and theoretical modeling.