The porphyry copper-molybdenum deposits of central Chile

摘要

The Late Miocene-Pliocene porphyry copper-molybdenum deposits of Central Chile are a byproduct of subduction of the Juan Fernandez ridge beneath South America. In addition to triggering ore deposit formation, this tectonic event also caused flat slab subduction, crustal thickening, cessation of volcan-ism, tectonic inversion of the host volcano-sedimentary sequences, uplift, erosion and development of a fault architecture favourable for the emplacement of mantle-derived melts at shallow levels within the upper crust. These melts were the primary source of brines, gases, sulfur and metals in the porphyry deposits, and processes that operated at the magmatic-hydrothermal transition were crucial for the release of large volumes of metal-laden hydrothermal fluids into the ore-forming environment. Subsequent hydrothermal processes, including fluid mixing, were responsible for high grade hypogene ore deposition.