The influence of enclosing rock type on barite deposits, eastern Pyrenees,Spain: fluid inclusion and isotope [Sr, S, O, C] data

The Rocabruna and Coll de Pal barite deposits, located in the eastern Pyren ees of Spain, fill karstic cavities within carbonate rocks of Cambrian and Devonian age, respectively, The deposits contain barite, chalcopyrite, tetr ahedrite, pyrite and minor sphalerite and galena with saddle dolomite and q uartz as gangue. Fluid inclusion data from Coll de Pal quartz and dolomite indicate that the mineralizing fluid was a polysaline CaCl2-rich brine, wit h temperatures between 125 and 150 degrees C, C and O isotopic compositions of carbonates in both deposits are consistent with a progressive increase in temperature during deposition. The delta(34)S values of barite, which ra nge from 14.2 to 15.9%, in Coll de Pal, and from 13.9 to 19.3%, in Rocabrun a, together with Sr-87/Sr-86 ratios ranging from 0.7118 to 0.7168 in Rocabr una, and from 0.7115 to 0.7136 in Coll de Pal? indicate two different fluid sources. We propose that these deposits formed as a result of mixing betwe en a Ba-rich, sulfate-poor hot fluid, and sulfate-rich solutions of surfici al origin. The different Sr isotope ratios in the deposits indicate that th e hot Ba-rich fluids involved in each deposit were equilibrated with differ ent rock types (carbonates and shales), in agreement with the geology of th e two areas.