Deciphering the structural controls and 3D geometry of high-grade ore shoots at Namoya Mine, Maniema Region, DRC.
Following an unexpected hiatus in orebody continuity at several pits at Namoya Mine, located in the Maniema Region of the DRC, Tect was requested by the Exploration Department of Banro Corporation to establish the structural controls on auriferous mineralization and to integrate these, along with mine-focused drilling and historical data, into a fully-constrained, structurally-accurate 3D implicit model of mineralized volumes. This re-modelling was required for an interim resource update, mine planning and exploration drillhole planning.
The scope of work involved structural and lithological pit mapping, diamond drill core review, structural interpretation of aeromagnetic data and structural analysis of mine- and deposit-scale features, in order to identify zones that were prone to preferential fluid throughput and concentrated auriferous mineralization. The interpretation considered deformation events, kinematics, fabric development, structural architecture, alteration and quartz vein orientation and infill. A robust paragenetic sequence was established by Brett Davis of Orefind.
3D implicit modelling of the orebodies in Leapfrog incorporated 1) Tect mapping, structural interpretation, structural analysis and the paragenetic sequence; 2) historical regional- and deposit-scale mapping data, including lithologies and structural readings; 3) historical drillhole data, including diamond, exploratory reverse circulation (RC) and grade control RC data, in addition to rip-line geochemical sampling; 4) attributed information and data extracted from publicly-available and in-house historical reports, presentations, memos and academic papers.
Tect’s analysis reveals that orebodies reflect fluid movement and concentration in dilational jogs, wherein clockwise rotation of mineralized zones along contacts and shears was accompanied by repeated fracturing and veining. These occurred in the context of dextral-transpressive kinematics. The modelled steeply-plunging ore shoots consist of interconnected, parallel to sub-parallel arrays of mineralized lenses, the spatial continuity of which is essentially a function of the degree of clockwise rotation. During mapping, Tect provided training in the use of mobile mapping devices to Banro Geologists.