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

•Reaction-enhanced permeability during greisenization promotes the expulsion of magmatic fluids.•The efficient expulsion of magmatic fluids during greisenization stabilizes fluid overpressures responsible for the opening of vein swarm within the host rocks.•Interplays between permeability and greisenization promote and enhance the transport of a large amount of fluid.•Reaction-enhanced permeability is a key mechanism for formation of large vein and greisen Sn-W deposits.