The Bingham deposit is centred on a small 40 Ma stock of older, generally equigranular, monzonite that is cut by quartz monzonite porphyry, latite, and quartz latite porphyry dykes. The surrounding country rocks are quartzite and minor but important limestone. A body of fractured rock formed over the top of the monzonite as it cooled leaving a weakly fractured core below a dome of strong fracturing. Early fluids entered this fractured mass at about the time of the intrusion of the first porphyry resulting in an undetermined amount of alteration and mineralisation. This fracturing is a major control on the location of the ore shell and the concentric zoning pattern of alteration and mineralisation. Five porphyry intrusives have been described and each is followed by a cycle of veining, alteration and mineralisation. The porphyries all trend north-easterly across the northern half of the deposit, forming the porphyry trend. At least three overlapping centres of fracturing, alteration and mineralisation seem to be present within the stock, one centred in the fracture dome and two or more in the porphyry trend.

More than fifty significant porphyry copper deposits are distributed over a 2000 km interval within the U.S. and Mexico, following a trend subparallel to the southwestern margin of North America. These include giant supergene enriched deposits such as those at Morenci in Arizona (4.7 Gt @ 0.52% Cu) and Cananea (7.1 Gt @ 0.42% Cu) in Sonora, Mexico.

The porphyry copper deposits of southwestern North America were developed in a continental margin cratonic setting, above a subduction zone that was active largely from the Early Mesozoic to the Late-Tertiary. While significant ore deposits of Jurassic to Mid-Tertiary age are known, the majority were emplaced between 72 and 55 Ma, during the peak of magmatic activity along the Laramide Arc. Laramide magmatism and crustal shortening ceased by around 50 Ma, in the mid Eocene, to be followed by a 15 m.y. period of magmatic quiescence, erosion and localised continental sedimentation, the Eocene Epeirogeny. This was succeeded from around 35 Ma by the Mid-Tertiary Orogeny, which persisted through the Oligocene to the Early Miocene and resulted in renewed, widespread volcanism, and by crustal extension. Extension was characterised by the development of listric, detachment and strike-slip faults, associated listric tilting of up to 60° or more, and the uplift and exposure of metamorphic core complexes. During the Mid- to Late-Miocene, between 18 and 10 Ma, the nature of tectonism in the region changed through a period of transition, from an extensional to a block faulted 'basin and range' regime which persists locally to the present. The typical basins are grabens or half grabens, with structural relief between the base of sediment filled basins and the crests of the adjacent ranges of from 2 to 4 km, and sometimes more than 6 km.

Antamina is the largest known copper-zinc skarn (>3000 Mt @ 1.1% Cu and 1.3% Zinc) in the world. It is located in the Northern Andes in Peru, 270 km north of Lima. The deposit formed at approximately 10 Ma by the emplacement of quartz monzonite intrusions into Mid to Late Cretaceous limestones of the Celendin and Jumasha Formations. Mineralisation is hosted as a series of zoned green and brown garnet endoskarns and exoskarns in the form of chalcopyrite, bornite and sphalerite. Elements present within the deposit of significant quantities to affect concentrate value are Cu, Zn, Mo, Ag, Bi and Pb. Antamina produces four concentrates, namely, copper (chalcopyrite and bornite), zinc (sphalerite), molybdenum and lead-silver-bismuth.

The Collahuasi district is located in northeastern Chile, approximately 200 km southeast of the port of Iquique. It defines an area of 1200 km2 in the Western Cordillera of the Andes Mountains, between altitudes of 4000 and 5000 m above sea level. The district hosts a cluster of mineralised centres that currently comprise three porphyry copper, associated high level epithermal vein, and palaeogravel-hosted exotic copper deposits. The Quebrada Blanca, Ujina and Rosario porphyry copper deposits are currently in production, as are the Huinquintipa exotic copper accumulations. The Collahuasi porphyry deposits are spatially associated with the West Fissure/Domeyko Fault System and appear to have been emplaced during a period of dextral transpression between 35-34 Ma.

The copper and molybdenum mineralisation of the Chuquicamata deposit has been known since the 19' century. The deposit is located within the Codelco Norte District in the Andes Ranges of northern Chile, 200 km northeast of the city of Antofagasta. Small miners initially worked the exposed oxidised outcrops and high grade oxide veins that were the surface expression of the deposit, although industrial scale mining did not commence until 1915 with open pit exploitation of the main disseminated oxides. Mining has continued to the present day, currently removing approximately 170 000 tonnes of ore and 400 000 tonnes of waste per day.

The Escondida porphyry copper deposit and its satellites are the source of ore for the world's current largest copper mine, with an installed capacity of 1.2 Mt of fine copper per annum. The published ore reserve + mineral resource at Escondida and the satellite Escondida Norte deposits at the end of 2004 totalled 2.88 Gt @ 1.13% Cu, or 10.11 Gt @ 0.70% Cu when lower grade leach and oxide ores are included. Escondida was discovered in 1981 as the culmination of an exploration program initiated in 1978. This program, the Atacama Project, was specifically targeted at locating supergene enriched porphyry copper ore within the 500 km interval between Chuquicamata and El Salvador, in the established porphyry copper belt of northern Chile.

The Bajo de la Alumbrera porphyry copper-gold deposit is located within the northern Sierras Pampeanas in the eastern Andes Mountains of northwestern Argentina. It formed in a tectonically favourable location within a major arc-oblique wrench fault system, the Tucuman Transfer Zone. Initial andesitic volcanism deposited on crystalline Lower Palaeozoic basement, and subsequently emplaced dacitic subvolcanic stocks are directly related to eastward subduction of the Nazca oceanic plate beneath the western continental margin of South America. Structural preparation and shallowing of the angle of subduction of the Nazca plate -related to the arc-normal Juan Fernandez Ridge on that plate - probably aided the ascent of calc-alkaline oceanic arc-related magma into the Tucuman Transfer Zone.

El Teniente, located in the Andes of central Chile, is the world's largest known Cu-Mo deposit with estimated resources of >75xl0 tonnes of fine Cu in ore with grades greater than 0.67%. Most of the high-grade hypogene Cu at El Teniente occurs in and surrounding multiple magmatic-hydrothermal breccia pipes. Mineralised breccia complexes, with Cu contents >1%, have vertical extents of >1.5 km, and their roots are as yet unknown. These breccias are hosted in a pervasively biotite-altered and mineralised mafic intrusive complex composed of gabbros, diabases, and porphyrinic basalts and basaltic andesites. The multiple breccias in El Teniente include Cu and sulphide-rich biotite, igneous, tourmaline and anhydrite breccias, and also magnetite and rock-flour breccias. Biotite breccias are surrounded by a dense stockwork of biotite-dominated veins which have produced pervasive biotite alteration and Cu mineralisation characterised by chalcopyrite » bornite + pyrite. Later veins, with various proportions of quartz, anhydrite, sericite, chlorite, tourmaline, feldspars and Cu and Mo sulphide minerals, formed in association with emplacement of younger breccias and felsic porphyry intrusions. These generated sericitic alteration in the upper levels of the deposit, and in some cases contributed more Cu, but in other cases eliminated or redistributed pre-existing mineralisation. Both the Teniente Dacite Porphyry and the central rock-flour Braden Pipe breccia, the dominant litho-structural unit in the deposit, are Cu-poor. Their emplacement at a late stage in the development of the deposit created a relatively barren core, surrounded by a thin (~^i50 m) zone of bornite > chalcopyrite, in the larger main area of chalcopyrite-rich, biotite-altered mafic rocks and mineralised breccias. The small Teniente Dacite Porphyry is not the "productive" pluton responsible for the enormous amount of Cu in the deposit. Instead, the deposition of the large amount of high grade Cu, and other key features of the deposit such as the barren core, are the result of the emplacement of multiple breccias generated by exsolution of magmatic fluids from a large, long-lived, open-system magma chamber cooling and crystallising at >4 km depth below the palaeosurface. It is for this reason that genetically El Teniente, like other giant Miocene and Pliocene Cu deposits in central Chile, is best considered a megabreccia deposit. The multistage emplacement of breccias, alteration and Cu mineralisation at El Teniente spanned a time period of >2 million years, between >7.1 and 4.4 Ma. This occurred at the end of a >10 million year episode of Miocene and Pliocene magmatic activity, just prior to the eastward migration of the Andean magmatic arc as a consequence of decreasing subduction angle due to the subduction of the Juan Fernandez Ridge below central Chile. Ridge subduction and decreasing subduction angle also caused crustal thickening, uplift and erosion, resulting in telescoping of the various breccias and felsic intrusions in the deposit. El Teniente is located at the intersection of major Andean structures, which focused magmatic activity and mineralisation at this one locality for an extended period of time.

Three of the world's largest Cu-Mo deposits, Los Pelambres, Rio Blanco-Los Bronces and El Teniente, formed in close temporal association with southward migration of the locus of subduction of the Juan Fernandez Ridge and the resultant decrease in subduction angle below central Chile during the Miocene and Pliocene. All three contain large Cu-mineralised magmatic-hydrothermal biotite itourmaline ±anhydrite breccia pipes generated by exsolution of saline, high-temperature fluids from crystallising magmas. Sr, Nd, Pb, S, Os, 0 and H isotopic data indicate that the metals these breccias contain, and aqueous fluids responsible for their emplacement, were derived from the same magmas that produced igneous rocks associated with each deposit. Isotopic data are consistent with derivation of these magmas from subduction-modified subarc mantle, and suggest that formation of these deposits did not involve either dehydration or melting of continental crust. Each deposit formed by multiple mineralising events occurring over a >2 m.y. period during which there is no evidence for coeval volcanic activity. Assuming an average Andean magma with 100 ppm Cu, the original lOOxlO6 tonnes of Cu in each deposit prior to erosion requires a parent body of magma with a batholith-size dimension of approximately >600 km3. We suggest that the multiple Cu-mineralised breccia pipes in each deposit were generated by exsolution of magmatic fluids from the roofs of large, long-lived, open-system magma chambers, crystallising at depths of >4 km below the palaeosurface as indicated by

The Chilean Andes comprise the most richly endowed copper province on Earth. A total resource (including production) of about 490 million tonnes of fine copper has been identified in more than 63 porphyry copper deposits and numerous prospects.

Andean porphyry deposits occur along five metallogenic belts that extend from central Chile to southern Peru and northwest Argentina. They formed between the Early-Late Cretaceous and Pliocene. Within these belts the deposits occur in clusters associated with multiphase plutonic complexes. This relationship is particularly prevalent in the Late Eocene-Oligocene belt, the most prolific of all. The time span between the oldest and youngest belt corresponds to the period in which contractional tectonism of the Andean cycle was established and developed from Late Cretaceous to Recent.