Abstract

NARANJO SIERRA, Edwin  and  ALVARAN ECHEVERRI, Mauricio. Fluid inclusion study of shear zone hosted lode gold type deposits: El Bagre mining district, Antioquia-Colombia. Earth Sci. Res. J. [online]. 2020, vol.24, n.3, pp.245-257.  Epub Apr 24, 2021. ISSN 1794-6190.  https://doi.org/10.15446/esrj.v24n3.80653.

The El Bagre mining district is located in the northeastern zone of the Antioquia department of Colombia, in the lower Cauca-Nechi river basin. The shear zone hosted lode-gold type deposits are located in the northern part of the El Bagre mining district. The characteristics of ore-forming fluids were investigated using fluid inclusion petrography and microthermometry analysis. Two stages, were identified in this study, namely a quartz-pyrite pre-mineralization stage (1) and a reactivation-sulfide-telluride mineralization stage (2). Microthermometry analysis revealed the presence of two types of fluid inclusions. Primary aqueous-carbonic inclusions (type I) are trapped in massive quartz, are characterized by the presence of clathrate, with salinities between 1.5 and 8.3 wt% NaCl equiv. and homogenization temperatures (to liquid) between 238.1° and 297.1°C. Secondary aqueous saline inclusions (type II) are trapped in reactivated quartz (type IIA) and crosscutting calcite veins (type IIB). The salinity displays a positive correlation trend from low to relatively high salinity, with 3.82 wt% NaCl equiv. (type IIB) to 9.21 wt% NaCl equiv. (type IIA). Homogenization to a liquid phase occurred between 150.8° and 210.6°C for the type IIA inclusions and between 130.3° and 190.4°C for the type IIB inclusions. Based on these results, the shear zone hosted lode-gold type deposits from the El Bagre mining district, show characteristics of orogenic gold deposits.

Keywords : Fluid inclusions; El Bagre Mining District; Shear Zone; Lode Gold Deposits.

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