STABLE-ISOTOPE COMPOSITION OF F-PB-ZN MINERALIZATION IN THE VALLE DE TENA (SPANISH CENTRAL PYRENEES)

This study, dealing with the stable isotope (C, O, and S) geochemistry of F-Pb Zn deposits, is part of an integrated metallogenetic study of the Valle de Tena (Central Pyrenees). The objective of this work is t o place constraints on the origin of the mineralizing solutions and so urces of sulphur and metals. Two types of mineralization have been ide ntified: (1) stratabound ores linked to an emersion episode that occur red during the Namurian to Westfalian transition (Portalet mines), and (2) low-temperature hydrothermal veins related to post-Hercynian exte nsional tectonics (Yenefrito and Lanuza mines, and Tebarray occurrence s). Stable isotopic study indicates that the source of mineralizing co mponents was the local Upper Palaeozoic country rocks in the case of t he stratabound Portalet deposit (biogenic sulphides and connate waters , modified by some meteoric input through a karst surface). In the cas e of vein deposits, stable isotopes point toward either modified conna te water or marine water as the mineralizing fluid, with sulphur and m etals derived from a mixture, in different proportions, of regional ig neous and (meta)sedimentary country rocks.