Abstract
This study re-evaluates the characteristics of Cu-Pb-Ag and Fe-Mn ore mineralization of the Kombat Mine and Gross Otavi Mine based on field geology, fluid inclusions, petrology, mineralogy, and geochemistry. This is to determine the genetic relationship between Fe-Mn and Cu-Pb-Ag mineralization. The study has established that the Cu-Pb-Ag ore at the Kombat Mine can be classified as a variant of MVT-type deposit, whereas the Fe-Mn ore can be classified as a stratiform-syn-sedimentary deposit. The formation of the MVT-type deposit is associated with a hydrothermal fluid system with a mean temperature of 183°C and mean salinity of 12.85 wt. % NaCl equivalent. The syn-sedimentary Fe-Mn ore, which is largely associated with calc-silicate lithologies, consists mainly of magnetite and hematite with minor pyrite, hausmannite and jacobsite, and was deposited by diagenetic and mixed diagenetic-hydrogenetic processes under changing oxic and anoxic conditions within the sedimentary basin. Acceptable geochemical exploration indicators of the existing mineralization include anomalous values above 0.5% Cu, 0.2% S; 0.05% Pb; 0.04% As; 0.01% Zn; V, W, Mo, and Ag are 0.002%. Mineralogical indicators include chalcopyrite, bornite, covellite and galena with minor chalcocite, sphalerite, and tennantite for the Cu-Pb MVT-type ores at Kombat Mine.
Highlights
The Kombat Mine is one of the most significant copper mines in Namibia
The X-Ray Diffraction (XRD) results presented in Table 1, shows that out of the fifty-nine (59) minerals identified in the Kombat samples, chalcopyrite, bornite, covellite and galena, with minor chalcocite, and sphalerite are the most common ones in the Cu-Pb (Ag-Zn-V) ore whiles, the Fe-Mn ore is dominated by hausmannite and hematite, with minor pyrite, jacobsite, manganite, magnetite, pyrolusite, rhodonite, and pyrobelonite
The carbonate hosted Kombat-style mineralization is structurally controlled and consists of discrete vertical ore zones constrained to faults, shear fractures and karst resembling the typical characteristics of a Mississippi Valley-type (MVT) deposit
Summary
The Kombat Mine is one of the most significant copper mines in Namibia. It originally commenced mining in 1962 and operated until 2008, producing 12.5 million tonnes of ore grading 2.6% Cu over this period [1] [2]. Six defined ore blocks have been delineated to date that are collectively termed Kombat Mine and are located on the northern limb of the canoe-shaped, doubly plunging Otavi Valley Synclinorium, in the contact zone between phyllite of the Kombat Formation and underlying dolomites of the upper Tsumeb Subgroup (Figure 1). This extends for over 4 km [3]. The unusual mineral association of the Kombat-style mineralization warrants a re-evaluation of the genetic relationship between iron-manganese and copper-lead silver ores The mine is unique in the Otavi Mountainland (OML) in that the base metal hosting massive and semi-massive sulfides, fracture veins and galena-rich alteration breccias are spatially associated with replacement iron-manganese oxide/silicate mineralization that hosts several unique minerals first described at Kombat Mine [4].
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