The impact of the linkage between grade distribution and petrofabric on the understanding of structurally controlled mineral deposits: Ouro Fino Gold Mine, Brazil

Abstract Ore deposit structural analysis, using a combination of structural geology and geostatistics, has direct application in the mining industry. Its main goal is to integrate structural measurements and assay data to create a method in which structurally controlled deposits are modeled numerically. This provides guidance to grade control and pit optimization during mining, improves prediction of orebody geometry and orientation, and provides more effective exploration strategies for surrounding areas. The method leads to a better understanding of how mineralized fluids percolated and were focused at the Ouro Fino Mine, a shear zone-hosted gold deposit in Minas Gerais State, Brazil. In this mine, gold is distributed along permeability pathways within rock fabrics that were produced or modified during the Brasiliano orogeny, when the Espinhaco–Aracuai sequence was inverted towards the Sao Francisco craton during a basement-involved fold-and-thrust regime. The resulting permeable zones are conformable with the C surface, within which two other clusters of fabric elements control the large-scale features of the mineralization: (1) a cluster of fabric elements (mineral, stretching and intersection lineations) that plunges SE; and (2) a sub-horizontal cluster along folds and intersection lineations and the strike of the shear zone.