Ore lead and sulphur isotope pattern from the low-temperature veins of the Catalonian Coastal Ranges (NE Spain)

Abstract

The lead isotopic composition of galenas from low-temperature veins of the Catalonian Coastal Ranges (NE Spain) displays a small but distinct range of values: 18.318 ≤206Pb/204Pb ≤ 18.678; 15.678 ≤207Pb/204Pb ≤ 15.767 and 38.534 ≤ 208Pb/204Pb ≤ 39.189. The data define a linear trend in the 208Pb/204Pb versus 206Pb/204Pb diagram that can be interpreted in terms of mixing of lead from different reservoirs. The lead appears to be derived from a solution that preferentially leached granites of Late-Hercynian age. Sulphur isotopic compositions of the galenas range from −8.5 to + 7.3‰ but variations in a single deposit are small (1–2‰), pointing to different sources of sulphur. In a δ34S versus 206Pb/204Pb plot no clear correlation trends appear. Lead isotope data from deposits of similar characteristics situated within the Hercynian orogenic belt as the Linares-La Carolina district (S Spain) and the Inglesiente-Sulcis area (Sardinia) show slight differences indicating a source area of similar lead isotopic composition. In the CCR and Linares-La Carolina districts, the main source of lead is related to the Hercynian granites of each area, although small contributions from metasediments cannot be ruled out. The contribution of lead from metasedimentary rocks is particularly seen in the Sardinian (Hercynian vein-type) ores.