Ore-controlling structures and geostatistical determination of ore-shoots in shear zone hosted lode gold type deposits, El Bagre-Antioquia, Colombia

Abstract

Shear zone hosted lode gold type deposits at the El Bagre in the northeastern zone of Antioquia department of Colombia, are the only evidence of Permian gold mineralization to date in Colombia Andes. Orebodies at the El Bagre are structurally controlled and are considered as the product of ore-forming fluids derived from at least two episodes of fluid flow between the shear zones, thus different fluid flow could lead to orebodies and ore shoots plunge in different directions. The La Ye orebodies tend to strike to the NNW-NS and plunge to the SW, Mangos orebodies tend to strike (as a whole) to the NS-NNE and plunge to the NE and Cordero orebodies tend to strike (as a whole) to the NNW-NS and plunge to the NE. The ellipses determined by variogram modelling for these orebodies, reveal the anisotropy of gold mineralization and therefore the orientation of ore-shoots. The long axes of the anisotropy ellipses trend SSE. These high grades distributions are related to sinistral shearing and NNW-SSE faulting during D3 deformation event. This study exemplifies a simple and effective tool for exploration strategies regarding of orebodies, ore-shoots and ore-controlling structures relationships