Abstract
Auriferous skarns are associated with post- and late-kinematic Hercynian granites that intruded into Cambro-Ordovician to Devonian sediments of the central Pyrenees. We determined the age of the Andorra granite and the associated skarn at 305 ± 3 Ma by U-Pb dating titanite from the endo-skarn. The sulfur isotopic composition from sulfides in the skarn (Cardellach et al. 1992) shows a significant variation with isotopically light sulfur (δ34S ≈ +3) in the barren skarns and heavy sulfur (δ34S ≈ +11) in the gold-bearing skarns. Outwards, it increasingly resembles sulfur from arsenopyrite disseminations in the Cambro-Ordovician sediments. The lead isotopic composition from sulfides of the skarns is very homogeneous (206Pb/204Pb = 18.410, 207Pb/204Pb = 15.699, 208Pb/204Pb = 38.574) in contrast to the one in gold-bearing arsenopyrite veins and in arsenopyrite disseminations in the sediments (e.g. 206Pb/204Pb varies from 18.54 to 30.36). Combined, sulfur and lead isotope data indicate that the lead in the skarn is dominantly derived from the granite, whereas the sulfur is derived at variable portions from both the granite and the sediments.
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Romer, R.L., Soler, A. U-Pb age and lead isotopic characterization of Au-bearing skarn related to the Andorra granite (central Pyrenees, Spain). Mineral. Deposita 30, 374–383 (1995). https://doi.org/10.1007/BF00202280
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DOI: https://doi.org/10.1007/BF00202280