Regional-scale evolution of the Laramide arc and porphyry copper province, southwestern North America

Porphyry copper provinces are time-space clusters of porphyry copper deposits (PCDs) that form in magmatic arcs. The evolution of the Laramide arc of southwestern North America, which hosts the Laramide porphyry copper province - the second-largest in the world - provides insight into factors contributing to its transient and localized metallogenic fertility. Regional-scale patterns are evident based on new and compiled U-Pb geochronological and whole-rock geochemical data, collected as part of an ongoing study. The migration of the locus of PCD formation coupled with shut-off of the magmatic arc and other geological evidence suggest localization of PCD formation near the southern margin of a shallowly subducting portion of the Farallon plate. Trends in increasing maximum size of PCDs and increasing SiO2 content of magmas with time correlate with the duration of arc activity in a given locale. Collectively, these trends suggest a variety of processes, including (1) uncertain ones related to local tectonic configuration, and (2) variations in crustal assimilation and/ or metasomatism, which are correlated to the local duration of arc magmatism, contributed to the richness of the Laramide porphyry copper province.