Hydrothermal controls on metal distribution in porphyry Cu (-Mo-Au) systems / Гидротермальный контроль распределения металлов в медно-(молибден-золото)-порфировых системах

Extensive research during the 20th century on porphyry Cu (-Mo-Au) deposits has revealed the following major geodynamic, petrological, mineralogical, and geochemical features that characterize these deposits: (1) these systems commonly occur in continental and oceanic magmatic arcs or in collisional orogenic belts; (2) they have spatial and genetic relationships to basaltic-to-felsic magmas emplaced in the upper 10 km of the crust; (3) lateral and vertical alteration-mineralization zoning consists of a Cu (± Mo ± Au) ore shell in the shallow portion of a potassic alteration zone, produced by magmatic fluids; this can be overprinted by phyllic alteration, also  largely magmatic in signature, that in turn may be overprinted by argillic alteration, with a dominantly meteoric signature; (4) associated deposits such as skarns, Cordilleran vein, and high and intermediate sulfidation epithermal deposits may occur above or adjacent to porphyry orebodies; (5) porphyry systems form from S- and metal-rich, single-phase aqueous fluid of moderate salinity (2–10 wt % NaCl equiv) exsolved from magmas; during its ascent toward the surface this fluid undergoes a variety of processes that can cause metal precipitation, including decompression, phase separation, cooling, interaction with host rocks, and mixing. <...>