Phanerozoic gold metallogeny in the colombian andes: a tectono-magmatic approach
- Autores: Hildebrando Leal Mejía
- Directores de la Tesis: Joan Carles Melgarejo i Draper (dir. tes.), Umberto Cordani (codir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2011
- Idioma: español
- Tribunal Calificador de la Tesis: Joaquin Antonio Proenza Fernández (presid.), Antoni Camprubi Cano (secret.), Victor A. Valencia (voc.)
- Materias:
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- Resumen
The Colombian Andes are comprised of a complex association of autochothonous, para-autochthonous and allochthonous components amalgamated along the northwestern margin of the Guiana Shield since the Meso-Proterozoic. Major faults and reactivated suture systems provided important controls on the emplacement of subduction-related calc-alkaline magmas throughout the Phanerozoic.A close spatial-temporal relationship between gold occurrences, calc-alkaline magmatism and Colombian tectonic evolution has been proposed in early regional metallogenic synthesis, but the lack of precise age data for constraining magmatic crystallization, and interpreting hydrothermal alteration and mineralization, rendered conclusions necessarily speculative.
In the present study, based upon historic data along with application of different analytical techniques such as petrography, mineralogical analyses, whole-rock geochemistry, isotope geochemistry and different geochronological methods, a regional synthesis of the Phanerozoic gold metallogeny in the Colombian Andes is presented.
At least seven gold metallogenic events are identified in the Phanerozoic: 1) Pre-Jurassic, 2) Jurassic, 3) Cretaceous, 4) Paleocene ¿ early Eocene 5) middle Eocene, 6) early Miocene, and 7) late Miocene to Pleistocene.
The Pre-Jurassic metallogenic event comprises vein-type mineralization at El Carmen Stock in the El Bagre Mining District as the only known gold occurrence.
The Jurassic metallogenic event includes different types and styles of gold mineralization at the Serranía de San Lucas region and the southern Ibague Batholith. They are related to the second of three east-to-west migrating magmatic arcs well-identified during Jurassic at ca. 210-200Ma, ca. 194-182Ma, and ca. 167-154Ma.
The Cretaceous metallogenic event comprises different intrusion related gold deposits associated to late Cretaceous intrusives including the Antioquia Batholith, the Buga Batholith and the Jejenes Stock.
The Paleocene - early Eocene metallogenic event includes the Paleocene adakite-like magmatic pulse of the `Nur River Trend¿ within the Antioquia Batholith magmatic suite and associated gold deposits (e.g. Cerro Gramalote). Mineralization of the Sonsón-Argelia, Maltería and Libano-Santa Isabel districts, spatially-related to the Sonsón Batholith, the Manizales Stock and the El Hatillo Stock, respectively, are also include within this event The middle Eocene metallogenic event comprises porphyry Cu(Au) mineralization associated to the Mandé-Acandí arc formed in an intra-oceanic environment and accreted later to the continent by the Miocene.
The early Miocene metallogenic event comprises vein-type mineralization spatially-related to the Piedrancha Batholith and associated stocks in the Nariño Department.
Finally, the late Miocene to Pleistocene (Neogene) metallogenic event comprises porphyry-type Au(Cu,Mo) and epithermal Au(Ag,As,Sb,Pb,Zn) occurrences associated to distinct arc segments migrating in time and space shifting in both, a south-to-north and west-to-east directions. In constitutes the most important metallogenic event as the majority of present-known gold resources in Colombia are associated with porphyry-related deposits of late Miocene age, including world-class deposits such as Angostura intermediate- to high-sulfidation epithermal mineralization in the Santander Massif, La Colosa Au porphyry in the Central Cordillera, and intermediate-sulfidation Zn-Pb-Ag-Au vein systems at Marmato in the Middle Cauca Trend, and Buriticá in the Western Cordillera New petrographic, mineralogical, geochemical and isotope data presented here, combined with regional tectonic studies demonstrate a close temporal-spatial relationship between Colombian gold metallogeny and the formation of subduction-related calc-alkaline arcs throughout the Phanerozoic.
