Geochronology of Mexican mineral deposits. III: The Taxco epithermal deposits, Guerrero

Abstract

New 40Ar/39Ar (34.96 ± 0.19 Ma) and U-Pb ages (35.44 ± 0.24 and 34.95 ± 0.37 Ma) obtained in this study for the Calavera group of dikes, which predate intermediate sulfidation epithermal mineralization in the Taxco mining district, constrain the formation of such deposits to less than 34.96 Ma (latest Eocene). These deposits might arguably have formed at ~ 33 Ma, thus coinciding in age with the La Azul fluorite deposits, within the same district. Although this age is significantly younger than previously existing estimations, the deposits at Taxco consistently cluster into a Late Eocene to Oligocene metallogenic event. Such event was closely associated with the volcanism in the northern part of the Sierra Madre del Sur, specifically to the most prominent flare-up of subduction-derived volcanism before it ceased in the region and refashioned into the Trans-Mexican Volcanic Belt.