3D Modeling and Mineral Resources Estimation of the Kofi Birrimian Gold deposit, Zone C, Mali

N Camara and Jean-Jacques Royer. ( 2015 )
in: Proceeding of the 13th Biennial SGA meeting

Abstract

A mineralogical study, 3D modeling and mineral resources estimation was performed on a gold deposit prospect (Zone C) located on the Western part of Kofi (Mali). The petrographical study reveals two gold mineralization phases: (i) gold as inclusions in pyrite as native and/or electrum form; (ii) a second disseminated phase of native gold in the pyrite veins cracks. Four types of hydrothermal alterations were recognized microscopically: epidotization, chloritization, carbonation, and albitization. The statistical analysis identifies five lithological classes (mafic dyke, felsic dyke, diabase, faulted breccia and intermediary quartz diorite). The presence of some minerals identified in the petrographical study was confirmed by correlations (Cr, Fe, Ni, Al, Ti, Na, Ca) recognizes through a principal component analyses (PCA) performed on the geochemical data. The geostatistical study identifies isotropic and continuous spatial structures for most of the elements, including gold mineralization. Spherical isotropic variograms of tenth of meters ranges (Ag ≈ 40m, Au ≈ 60m) were adjusted for the geostatistical mineral reserve estimation. They were used to estimate the grade spatial variability in the prospect area. 3D maps show coincidences between hydrothermal alteration zones controlling the mineralization. The superposition of the Ag, B, Hg, As, and Na anomalies also show some spatial coincidences with the tourmalinization alteration zones (B), the albitization (Na) and the silver (and probably Au) mineralization. These results are in agreement with those obtained by the company.

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    BibTeX Reference

    @INPROCEEDINGS{Camara:2015,
        author = { Camara, N and Royer, Jean-Jacques },
        editor = { SGA },
         title = { 3D Modeling and Mineral Resources Estimation of the Kofi Birrimian Gold deposit, Zone C, Mali },
         month = { "aug" },
     booktitle = { Proceeding of the 13th Biennial SGA meeting },
        series = { Symposium B },
        volume = { 5 },
          year = { 2015 },
       address = { Nancy, France },
      abstract = { A mineralogical study, 3D modeling and mineral resources estimation was performed on a gold deposit prospect (Zone C) located on the Western part of Kofi (Mali). The petrographical study reveals two gold mineralization phases: (i) gold as inclusions in pyrite as native and/or electrum form; (ii) a second disseminated phase of native gold in the pyrite veins cracks. Four types of hydrothermal alterations were recognized microscopically: epidotization, chloritization, carbonation, and albitization. The statistical analysis identifies five lithological classes (mafic dyke, felsic dyke, diabase, faulted breccia and intermediary quartz diorite). The presence of some minerals identified in the petrographical study was confirmed by correlations (Cr, Fe, Ni, Al, Ti, Na, Ca) recognizes through a principal component analyses (PCA) performed on the geochemical data. The geostatistical study identifies isotropic and continuous spatial structures for most of the elements, including gold mineralization. Spherical isotropic variograms of tenth of meters ranges (Ag ≈ 40m, Au ≈ 60m) were adjusted for the geostatistical mineral reserve estimation. They were used to estimate the grade spatial variability in the prospect area. 3D maps show coincidences between hydrothermal alteration zones controlling the mineralization. The superposition of the Ag, B, Hg, As, and Na anomalies also show some spatial coincidences with the tourmalinization alteration zones (B), the albitization (Na) and the silver (and probably Au) mineralization. These results are in agreement with those obtained by the company. }
    }