transitions from normal to flat and then back to normal subduction produces a series of effects that can lead to the generation of porphyry deposits. Initially, there will be decreased alkalic magmatism, horizontal shortening, hydration of the lithosphere above the flat-slab, and low heat flow. Upon a return to normal subduction, the hot asthenosphere will once again interact with the hydrated mantle, causing wet melting, crustal melting will ensue as mantle melts pass through, and lithospheric thinning and weakening due to the increased heat flow. The subducting slab can be lifted by aseismic ridges, seamount chains, or oceanic plateaus – which can provide a favourable environment for the development of a porphyry deposit. This interaction between subduction zones and the aforementioned oceanic features can explain the development of multiple metallogenic belts in a given region; as each time the subduction zone interacts with one of these features it can lead to ore genesis. Finally, in oceanic island arcs, ridge subduction can lead to slab flattening or arc reversal; whereas, in continental arcs it can lead to periods of flat flab subduction. Arc reversal has been shown to slightly pre-date the formation of porphyry deposits in the south-west Pacific, after a collisional event. Arc reversal occurs due to collision between an island arc and either another island arc, a continent, or an oceanic plateau. The collision may result in the termination of subduction and thereby induce mantle melting. Porphyry deposits do not generally have any requisite structural controls for their formation; although major faults and lineaments are associated with some. The presence of intra-arc fault systems are beneficial, as they can localize porphyry development. Furthermore, some authors have indicated that the occurrence of intersections between continent-scale traverse fault zones and arc-parallel structures are associated with porphyry formation. This is actually the case of Chile's Los Bronces and El Teniente porphyry copper deposits each of which lies at the intersection of two fault systems. It has been proposed that "misoriented" deep-seated faults that were inactive during magmatism are important zones where porphyry copper-forming magmas stagnate allowing them to achieve their typical igneous differentiation. At a given time differentiated magmas would burst violently out of these fault-traps and head to shallower places in the crust where porphyry copper deposits would be formed. Characteristics Characteristics of porphyry copper deposits include: The orebodies are associated with multiple intrusions and dikes of diorite to quartz monzonite