Fluid inclusion studies on Mt. Capanne pegmatites, Isola d'Elba, Tuscany, Italy
Fluid inclusion studies on Mt. Capanne pegmatites, Isola d'Elba, Tuscany, Italy (in Proceedings of the Eleventh European symposium on Fluid inclusions research (ECROFI XI), Benedetto De Vivo (editor) and Pierfranco Lattanzi (editor))
European Journal of Mineralogy (October 1992) 4 (5): 1085-1096
The fluids trapped in inclusions in pegmatitic minerals and surrounding rocks from this area document the evolution of the system from a high-T (> 500 degrees C assuming a P of 1.5 kbar), water-rich fluid, containing small amounts of CO (sub 2) , CH (sub 4) , H (sub 2) S and N (sub 2) , through an intermediate (approx 400 degrees C) fluid, down to a low-T (approx 300 degrees C) fluid. Salinities remained constantly low (max. approx 7 eq.wt.% NaCl); Na, K and Cl appear as major components of the dissolved salts. The lowest salinity values are typical of the lowest T fluids, and may indicate the input of a largely meteoric component, as opposed to fluids of the earliest stage, for which a dominantly magmatic nature is suggested. Whether this early magmatic fluid coexisted with a silicate-rich melt remains an open question, although the presence of early crystal-rich inclusions may support such a coexistence.