New U-Pb and Re-Os geochronology of Laramide porphyry copper mineralization along the Cananea lineament, northeastern Sonora, Mexico: Contribution to the understanding of the Cananea copper district

The Cananea mining district constitutes the cluster of deposits that is richest in Cu in Mexico, which, together with the porphyry copper deposits from southern Arizona and western New Mexico, is part of one of the largest copper provinces on Earth. The main mineralized localities within the district are the Buenavista del Cobre, Mariquita, Milpillas, Lucy, Maria, El Alacrán, and El Pilar deposits. The Buenavista del Cobre is by far the economically most important site with more than 30 Mt of Cu, which places it among a select group of world-class giant porphyry copper deposits. This study presents new Re-Os molybdenite and U-Pb zircon ages, which help to better constrain the metallogenetic history of the district. According to the Re-Os data, the earliest mineralizing pulse occurred at the El Pilar (73.9 Ma), followed by the Milpillas (63.0 to 63.1 Ma), Lucy (61.6 to 61.8 Ma), Maria (60.4 Ma), El Alacrán (60.8 to 60.9 Ma), Buenavista del Cobre (59.2 to 59.3 Ma), and Mariquita (59.3 ± 0.3 Ma) deposits. Excluding El Pilar, the main mineralizing pulses occurred within a relatively short time window of ~ 4 Ma. U-Pb zircon ages of the ore-related plutons indicate the entire magmatic activity occurred between 77.7 and 57.8 Ma. The Re-Os and U-Pb data display a NW to SE migration of the plutonic and mineralizing events along the trace of the Cananea lineament, suggesting this migration might be coupled with such feature. Further Cenozoic Basin-and-Range block faulting led to burial or exhumation of the ore systems. Moreover, extension promoted the formation of important supergene enriched chalcocite blankets, and lateral migration of copper solutions, yielding conditions to develop exotic copper mineralization.