Formation of systems of parallel greisen lodes in the granites of SW England

摘要

Swarms of parallel lodes containing an assemblage of quartz-feldspar-wolframite-cassiterite-muscovite together with variable amounts of loellingite, copper-tin sulphides and molybdenite, with or without topaz, fluorite, apatite and/or accessory tourmaline and with well-defined selvedges of alteration are recognised to be one of the characteristic expression of the pneumatolytic stage of mineralization in peraluminous, S-type granites. Observations of well-exposed systems in SW England are used to place constraints on the conditions under which the fractures formed and the minerals were deposited.