Características geológicas, isotópicas y estructurales del depósito vetiforme Los Mangos, Antioquia-Colombia

Resumen

La mina Los Mangos es un depósito vetiforme encajado en una zona de cizalla sinestral con deformación frágildúctil que generó milonitización de la roca encajonante, estructuras sigmoidales, boudinage y contactos veta-caja reactivados con presencia de salbanda (gouge). Se observaron al menos dos etapas de mineralización: la primera caracterizada por Qz + Py ± Au y la segunda etapa por Qz + Py + Cpy + Gn + telururos de Au-Ag (silvanita y hessita) + telururos de Pb (altaita) + telururos de Au (calaverita) + telururos de Hg (coloradoita). Las alteraciones hidrotermales y la asociación paragenética observada permite sugerir que especies como H2S o HS- fueron dominantes en los fluidos mineralizantes y en consecuencia, el complejo Au(HS)-fue probablemente el ligante y el medio de transporte del Au. La presencia de texturas de recristalización tipo Bulging permitieron inferir condiciones de temperatura bajas (<350°C) y condiciones de deformación frágil-dúctil. Los valores isotópicos de δ18O en moscovitas hidrotermales varían entre +11,5 y +12,9%o, los valores de δD varían entre -58,5 y -63,4%o y los valores de azufre δ34S en pirita varían entre +3,0 y +1,0%o. Los valores de δ18Oagua varían entre +10,6%o y 12,0%o y los valores de δDagua varían entre -43,4%o y -38,5%o. Estos valores isotópicos de δ18O, δD y δ34S muestran una afinidad magmática y/o metamórfica para el fluido mineralizante. Las características geológicas del depósito, incluyendo control estructural, mineralogía, roca encajante, alteración hidrotermal, estilo de mineralización y composición isotópica de δ18O, δD y δ34S, indican que el depósito en la mina Los Mangos es compatible con el modelo de depósitos de oro orogénico (Orogenic Gold Deposits) del subtipo: Depósitos de Filones Auríferos Hospedados en Granitoides (Granitoid-Hosted Lode-gold Deposits).

Palabras clave: Mina Los Mangos, oro orogénico, vetiforme, zona de cizalla, telururos, isótopos estables

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Biografía del autor

Edwin Naranjo-Sierra, Operadora Minera S.A.S.

Medellín, Colombia

Mauricio Alvarán-Echeverri, Universidad de Caldas

Departamento de Ciencias Geológicas, Manizales, Colombia.

Citas

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Publicado
2018-02-23