Abstract

NARANJO-SIERRA, Edwin  and  ALVARAN-ECHEVERRI, Mauricio. Geological, isotopic and structural characteristics of Los Mangos lode gold type deposit, Antioquia-Colombia. bol.geol. [online]. 2018, vol.40, n.1, pp.93-108. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v40n1-2018006.

Los Mangos is a shear-zone hosted lode gold type deposit with brittle-ductile deformation, which produced wallrock mylonitization, sigmoidal structures, boudinage and reactivation of vein-wallrock contact. At least two mineralization events were identified: Qz + Py ± Au for the first stage and Qz + Py + Cpy + Gn + Au-Ag tellurides (silvanite and hessite) + Pb tellurides (altaite) + Au tellurides (calaverite) + Hg tellurides (coloradoite) for the second stage. Hydrothermal alteration and paragenetic association suggest that H2S or HS- were the predominant sulfur species in ore fluids and, in consequence Au(HS)- 2 was likely the gold-transporting complex. Recrystallized quartz textures suggest low temperature (<350°) and brittle-ductile conditions. The δ18O values of hydrothermal muscovite are +11,5 to +12,9%o, the δD values are -58,5 to -63,4%o and the δ34S values of pyrite are +3,0 and +1,0%o. The δ18Owater values are +10,6%o to +12,0%o and the δDwater values are -43,4%o and -38,5%o. These isotopic values are compatible with a magmatic and/or metamorphic origin for the ore fluids. These geological characteristics including structural controls, nature host-rock, hydrothermal alterations, mineralization style and isotopic composition of δ18O, δD and δ34S suggest that Los Mangos lode type deposit is compatible with the Orogenic Gold Deposits of Granitoid-Hosted Lode-gold Deposits subtype.

Keywords : Los Mangos mine; orogenic gold; lode; shear zone; tellurides; stable isotopes.

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