Although numerous papers have been written on the geologic and metallogenic features of the Andes, a satisfactory hypothesis in regard to distribution of mineralization has not been presented. Previous studies of sedimentary rocks, erosion, and structure have shown only that they had local influence. Geochemical studies of igneous rocks for 11 trace elements were plotted with respect to the distance of the rocks from the Peru-Chile trench. Analyses of the geochemical contents permitted the division of the Andean orogene into two main provinces. The western province is characterized by decreasing copper content and increasing nickel, cobalt, and nickel/cobalt ratio from west to east. The eastern province is defined by high contents of lithium, rubidium, lead, and zinc.

Three structural divisions were noted. On the west, the Precambrian shield was weakly deformed during the Hercynian orogeny. The Hercynian belt on the east has a highly folded series of sandstones and shales. Between these two zones, the Altiplano is a highly mobile joint between the two mechanically different domains.