Three distinct porphyry copper subbelts are defined in the Colombian Andes: (1) a western subbelt emplaced during the early to middle Eocene in an oceanic domain, underlain by ophiolitic basement, along the western side of the Western Cordillera; (2) a composite eastern subbelt generated during the Middle Jurassic to earliest Cretaceous in a continental domain, underlain by elements of the Guyana Shield, along the eastern side of the Central Cordillera and the western side of the Eastern Cordillera; and, between the two, (:3) a central subbelt formed in the early to late Miocene at the contact of the oceanic and continental domains along the Cauca-Patla depression and its flanks. K-Ar geochronometry undertaken as part of this study provided preferred minimum ages of: 54.7 q-1.:3 m.y. for Murind6, 48.1 q-1.0 m.y. for Acandl, and 42.7 q-0.9 m.y. for PantanosPegadorcito in the western subbelt; 166 q-4 m.y. for Mocoa, 166 q-4 m.y. for Dolores, 144 q-$ m.y. for California, and 151 q-2 m.y. for Infierno-Chili in the eastern subbelt; and 17.4 q-0.4 m.y. for Piedrasentada in the central subbelt.The porphyry copper prospects are associated with dacite to tonalire porphyry stocks, which in the western and eastern subbelts intruded batholiths emplaced perhaps 15 to $0 m.y. earlier but which in the central subbelt are isolated within metamorphic or sedimentary host rocks. The porphyry copper systems exhibit a variety of alteration patterns, with potassium silicate and sericitic alteration important in the highest grade prospects and propylitization predominant in low-grade occurrences. None of the prospects displays significant supergene enrichment. Although porphyry coppers in the continental domain tend to be more molybdenum rich than those in the oceanic domain, gold-rich prospects occur in both settings, as do major lode gold deposits.The Jurassic and Miocene subbelts are interpreted to have been emplaced during eastward subduction at Andean-type continental margins, whereas the western Eocene subbelt could have been generated in either a modified Andean-type setting or in an intraoceanic island arc prior to its accretion to the continental edge.

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