First lead isotopic data for cinnabar in the Almadén district (Spain): implications for the genesis of the mercury deposits

Abstract

The Almadén district constitutes the largest and probably the most intriguing mercury concentration in the world. This paper reports the first lead isotope compositions of cinnabar from the district. Whole samples and stepwise leaching cinnabar aliquots display relatively homogeneous isotopic compositions (206Pb/204Pb = 18.112 - 18.460; 207Pb/204Pb = 15.635 - 15.705; 208Pb/204Pb = 38.531 - 38.826). Taken together with Jébrak et al. (2002) pyrite lead isotope results, the new cinnabar isotopic data defines a steep array trend on the 207Pb/204Pb - 206Pb/204Pb diagram, suggesting a mixed contribution from both ancient upper continental crust and (enriched mantle derived) magmatic sources for the ores of the Almadén Hg deposits