How greisenization could trigger the formation of large vein-and-greisen Sn-W deposits: A numerical investigation applied to the Panasqueira deposit

The formation of large tin-tungsten (Sn-W) deposits around granitic intrusions requires the circulation volumes fluids within permeable structures. Half world’s tungsten production originates from highly mineralized veins above and altered part granite (the greisen), whose results intense fluid-rock interactions. During greisenization processes, mineral reactions involve a decrease in rock volume thus an increase porosity permeability. To understand complex interactions leading to Sn-W ore deposits, we conducted numerical modeling accounting for magmatic fluid realistic permeability changes due alteration overpressure hosting rocks. water/rock ratio is computed constrain rate therefore evolution laws. Four model are presented: with without exsolved magma, dynamic reaction-enhanced greisen reproduced, thickness reaches 200 m more sophisticated model. interplay between creates zones that could localize structures such as swarm observed at Panasqueira. Dynamic promotes high velocity exchanges result by enhancing mass transfer intrusions.