Stable isotope geochemistry of the Ulldemolins Pb-Zn-Cu deposit (SW Catalonian Coastal Ranges, Spain)

Authors

  • P. ALFONSO Departament d’Enginyeria Minera i Recursos Naturals, Universitat Politècnica de Catalunya (UPC). Av. de les Bases de Manresa 61-73, 08242 Manresa, Barcelona, Spain.
  • C. CANET Departamento de Recursos Naturales, Instituto de Geofísica, Universidad Nacional Autónoma de México. Ciudad Universitaria, Del. Coyoacán, México DF, 04510, Mexico
  • Joan-Carles Melgarejo i Draper Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB). C/ Martí i Franquès, s/n, Spain
  • J.M. MATA I PERELLÓ Departament d’Enginyeria Minera i Recursos Naturals, Universitat Politècnica de Catalunya (UPC). Av. de les Bases de Manresa 61-73, 08242 Manresa, Barcelona, Spain.
  • A.E. FALLIK Isotope Geosciences Unit, Scottish Universities Environmental Research Centre. East Kilbride, Glasgow, G75 0QF, Scotland (UK)

Keywords:

Ore deposits, Skarn, Calcsilicates, Stable isotopes, Fluid inclusions

Abstract

The Pb-Zn-Cu deposit of Ulldemolins occurs within the Carboniferous sedimentary series of the southernmost Catalonian Coastal Ranges. It consists of sulphide-bearing calc-silicate assemblages, with epidote, Ca-amphiboles and Ca-garnet, which develop selectively along a dolomicrite bed near the contact with a granite porphyry. Two mineralisation styles can be differentiated: a) banded and b) irregular. Fluid inclusions and stable isotope compositions of sulphur in sulphides (sphalerite, galena and chalcopyrite) and carbon and oxygen in carbonates (calcite and dolomite) were studied in order to constrain the genesis and the source of mineralizing fluids. Fluid inclusions in sphalerite and calcite are aqueous, liquid+vapour and have a salinity between 1.2 and 7.2 wt% NaCl eq. and homogenization temperatures in the range of 273º to 368ºC. The δ4S(V-CDT) values in the banded mineralisation are mostly between –1.5 and +2.1‰, and those from the irregular mineralisation are between –1.1 and +20.5‰. These δ4S values of the banded mineralisation are in agreement with a magmatic origin of sulphur. In addition, the δ8O(SMOW) values of hydrothermal calcite, from +6.9 to +12.5‰, are consistent with a magmatic origin of the fluids that formed the banded ore deposit. Later, a new input of fluids interacted with the previously formed mineral assemblages and modified part of the deposit, leading locally to an irregular skarn mineralisation.

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Published

2012-07-20

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