Andean arc and backarc magmatic and tectonic processes and the formation of giant Cu, Au and Ag porphyry deposits

A long-outstanding question has been the relation between Andean arc and backarc magmatic and tectonic processes and the formation of giant Andean Cu, Au, Ag, Zn and Sn deposits. Integrating geochemical, geophysical and structural studies provides insights into some possible links in the Neogene Andes of Chile, Argentina and Bolivia. The relation of Andean tectonic processes and ore deposits are explored in two examples. The first involves the role of shallowing subduction zones related to aseismic ridge collision, crustal thickening and forearc subduction erosion in setting the stage for generating the giant Miocene-Pliocene Cu-Au porphyries in the largely igneous crust of the Chilean flatslab and surrounding region of Chile and Argentina. The second involves the role of a steepening subduction zone, a peak in extreme crustal thickening related to compressional deformation and lower crustal flow, and the incorporation of crust and lithosphere removed by delamination into the mantle wedge in generating the giant Ag-Sn-Zn deposits in the more sediment-rich crust and older Precambrian basement of the Andean backarc in the Bolivian Altiplano