Petrogenesis of the Miocene Morro del Cobre Cu (Mo)-porphyry deposit in the Frontal Cordillera over the Pampean flat-slab segment, Argentina

摘要

The Morro del Cobre porphyry (Cu-Mo-Au) deposit, genetically linked to the upper Miocene magmatism (～9-10 Ma), is located at the eastern margin of the Andean Frontal Cordillera of San Juan, Argentina, over the Pampean flat-slab segment (28-33°S) of the Central Andes. The petrogenetic analysis of these rocks reveals an arc affinity and an adakite-like signature with the source magmas evolving under thickened crust conditions which resulted in a high pressure (amphibole ± garnet) residual mineralogy. These mineralizing magmas, that evolved towards shallower magma chambers (＜ 10 km) have hydrous and oxidant character, typical of fertile suites worldwide. The emplacement of Morro del Co-bre coincides with the passage of the aseismic Juan Fernandez Ridge as many other Miocene productive porphyry deposits in this segment of the Andes.