THE VOLCANOGENIC MASSIVE SULFIDE DEPOSITS OF MEXICO

The vast majority of the volcanogenic massive sulfide deposits (VMS) of Mexico, more than 60 localities, are located in the Cretaceous Guerrero terrane of western Mexico. Two VMS localities occur in other tectonostratigraphic terranes. The Buenos Aires VMS is hosted by Paleozoic metamorphic rocks of the Sierra Madre terrane of eastern Mexico and Valle de Olivos is hosted in the Cretaceous Parral terrane of northern Mexico. The VMS deposits of Mexico have contributed with a small portion of its base and precious metals production. Recent VMS discoverings, like San Nicolas and Francisco I. Madero, Zacatecas, and Campo Morado, Guerrero, hosted by Guerrero terrane rocks, have renewed their economic interest. The largest deposits, up to 80 Mt are hosted in evolved oceanic island arcs associated to rhyolitic rocks and are Zn-Pb-Cu-Ag-Au Kuroko type. Cu-Zn-Au deposits are hosted in more primitive basaltic to andesitic volcanic and volcaniclastic rocks of the Guerrero terrane. The Valle de Olivos is considered a Zn-Pb-Cu-Ag-Au Kuroko type deposit. The Paleozoic Buenos Aires Cu-Zn-Ag deposit is a Besshi type deposit. All of the Mexican VMS deposits have suffered greenschist metamorphism and the have been recrystallized.