Project Description and Location
The Mutanga Uranium Project consists of three main deposits; Mutanga, Dibwe and Dibwe East, which make up the bulk of the Mineral Resources described herein. There are also three minor deposits called Mutanga East, Mutanga Extension and Mutanga West. In addition several other mineral prospects have been identified.
The Mutanga Project area is situated in the Southern Province of Zambia about 200 km south of Lusaka immediately north of Lake Kariba, approximately 31 kilometres northwest of Siavonga.
GoviEx acquired 100% of the Mutanga Project (“the Project”) in 2016 from Denison Mines Corp. (“Denison”). Denison had acquired 100% of the Project in 2007 through the acquisition of OmegaCorp Limited (“Omega”).
The Mutanga Project is currently comprised of two mining licenses (13880-HQ-LML and 13881-HQ-LML) encompassing 457.3 square kilometres. The mining licenses have a term of 25 years to April 2035.
Regionally, the Karoo Supergroup is a thick succession of late Carboniferous to late Triassic terrestrial strata deposited across much of what is now southern Africa. The Karoo Supergroup comprises at least six regional depositional sequences, which reflect broadly synchronous episodes of basin subsidence and climate change, but vary considerably in detail from one sub-basin to another. Karoo strata typically overlie Precambrian crystalline basement rocks.
Three formations in the Lower Karoo Supergroup in the mid-Zambezi Valley of southern Zambia and four in the Upper Karoo Supergroup have been identified. The Late Carboniferous – Permian Lower Karoo Supergroup consists of the basal Siankondobo Sandstone Formation, overlain by the Gwembe Coal Formation, in turn overlain by the Madumabisa Mudstone Formation. The Triassic - Early Jurassic Upper Karoo Supergroup is sub-divided into the Escarpment Grit, overlain by the Interbedded Sandstone and Mudstone, the Red Sandstone and the Batoka Basalt Formation.
The Escarpment Grit sandstones are interpreted to be fluvial deposits, but they record a major change in fluvial style. Maps produced in the 1970s show southwesterly directed paleocurrents in the “Braided Facies” throughout most of the Mutanga region. The relatively small variance in paleocurrent direction, prevalence of trough cross-bedded sandstones, pebbly sandstones and conglomerates and lack of laterally extensive beds all support interpretation of the “Braided Facies” sandstones as braided stream deposits.
In the overlying “Meandering Facies” member, thick, upward-fining sandstone beds with cross-bedding and ripple lamination; locally capped by mudstones which can be traced laterally for hundreds of meters, are likely point-bar and flood plain deposits.
The uranium mineralisation identified to date appears to be restricted to the Escarpment Grit Formation (“EGF”). Dibwe East is predominantly composed of EGF. The surface geology is characterised by a few scattered sandstone outcrops. Two major units can be distinguished, the “Braided facies” member (EGFb-f) of the lower EGF and the “Meandering facies” member (EGBm-f) of the upper EGF in core, the two units appear to be transitional from one another. The “Braided Facies” is distinguished in outcrop as gritstones, very-coarse-grained to coarse grained sandstones and pebbly sandstones. Ripple lamination is common and mudstone beds are laterally continuous.
Mineralization appears to be later than at least some of the normal faults which cut the Escarpment Grit Formation. This is evident from the good correlation of the radiometric logging data between adjacent holes within the Mutanga mineral deposit separated by interpreted faulting.
The source of the uranium is believed to be the surrounding Proterozoic gneisses and plutonic basement rocks. Having been weathered from these rocks, the uranium was dissolved, transported in solution and precipitated under reducing conditions in siltstones and sandstones. Post lithification fluctuations in the groundwater table caused dissolution, mobilization and redeposition of uranium in reducing, often clay-rich zones and along fractures.
In 2006 a detailed aeromagnetic and radiometric survey (Symons and Sigfrid, Report on the Interpretation of Aeromagnetic and Radiometric data 2006) was completed over the areas of interest which were revealed during an earlier pre-digital airborne survey. The 2006 survey has confirmed the position and tenor of the existing targets and identified additional, targets.
Prior to Omega/Denison involvement, AGIP and the Zambian geological survey undertook drilling across the Mutanga project area.
The drill program consisted of 14,794 metres of drilling (50 diamond holes for 6833 metres, 119 percussive (wagon drill) holes for 6998 metres and 83 percussive (shallow wagon drill) holes for 963 metres.
In 2006, 11 diamond drill holes were drilled by OmegaCorp to twin previous drilling at the Mutanga mineral deposit. Results confirmed the broad tenor of the historical U3O8 intercepts. Work was also carried out at Bungua, Mutanga and at Dibwe.
During 2007 to 2008 Denison completed work on the Mutanga mineral deposits, focussing on the Mutanga area and the Dibwe area in particular. The work included an appraisal of all available data (maps, plans, sections, limited geological interpretations and radiometrics and AGIP resource estimations). From this information Denison produced several databases covering Mutanga and other prospects.
After a two year delay due to suspension of exploration activities, a two phase drilling campaign resumed in April, 2011. Phase 1 drilling on Dibwe East and Mutanga West targets commenced in April and ended in July 2011 with 72 holes being drilled for a total of 7,564 m. The results for Phase 1 confirmed the continuity of uranium mineralization identified in 2008 drilling program at Dibwe East with a northeast-southwest strike length greater than 2.5 km. Results from the Mutanga West target still require further evaluation and are not considered material to the current Mutanga West resource.
Based on the encouraging results obtained with the Phase 1 drilling over the Dibwe East Zones 1 and 2 targets, a Phase 2 drilling program of 74 holes totalling 7,732 m was completed between August-October 2011. This drilling program discovered primary mineralization at depth and it also increased the strike length to 4.0 km.
Exploration for uranium typically involves identification and testing of sandstones within reduced sedimentary sequences. The primary method of collecting information is through extensive drilling (both RC and diamond drill coring) and the use of downhole geophysical probes. The downhole geophysical probes measure the electrical properties of the rock from which lithologic information can be derived and natural gamma radiation, from which an indirect estimate of uranium content can be made. The downhole geophysical probes measure conductivity, resistivity, self-potential, SPR, deviation and natural gamma. Geophysical probe data was collected from drilling over the property.
Metallurgical Test Work
Metallurgical test work (2012) has been completed by Mintek, South Africa on Dibwe East Deposit drill core samples. Denison supplied Mintek with 18 drill core samples, which were sourced from three different zones over Dibwe East. The test work included head sample characterization and preliminary bottle roll leach tests.
The average grade of samples was 586ppm U3O8. This is higher than the grades of the Mutanga (237 ppm U3O8) and Dibwe (247 ppm U3O8) mineral deposits.
Bottle roll leach tests (-25mm samples) yielded averaged uranium extractions of 85% which are comparable to results achieved for Mutanga (85%) and higher than for Dibwe (75%).
Leaching of fine milled material on six of the drill core samples achieved similar uranium extractions as for the - 25 mm samples. Therefore it appears that the uranium-bearing minerals of the Dibwe East samples are reasonably accessible to leaching at a crush size of -25 mm.
The average acid consumption of 10 kg/t for the Dibwe East samples is comparable to that of Dibwe (12 kg/t); both being higher than for Mutanga (2.3 kg/t).