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Namdini Gold Deposit, Northern Ghana – 5.1Moz Reserve

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Namdini Gold Deposit, Northern Ghana – 5.1Moz Reserve Namdini Gold Deposit, Northern Ghana – 5.1Moz Reserve Kevin Tomlinson (MAIG, Presenter), Paul Abbott (MGeol Soc SA), Ernest Opoku- Boamah (AIG), Richard Bray (RPGeo, AIG), Ekow Taylor (CP, AUSIMM) Contact: Cardinal Resources Limited, Suite 1, 28 Ord Street West Perth, WA 6000 Kevin Tomlinson: [email protected] Abstract Namdini represents the first major discovery in Ghana since 2009. The Namdini Mineral Resource represents the largest gold discovery in the Birimian of West Africa this century. Approximately 5.1 million ounces of gold Ore Reserves from a 7.4 million ounces Mineral Resource within a massive single deposit with a strike length of approximately 1.2km and a width of 350m. The deposit is still open at depth and along strike to the north and south and has been drilled to a vertical depth of 475m. The Namdini deposit is located within a large‐scale renewable mining licence granted by the Ghanaian government for an initial 15 years. The bulk of gold production in Ghana is in the southwest from some major gold mines but whilst the northern part is still relatively underexplored, it already has several producing mines there and across the border into nearby Burkina Faso. The producing mine on the Ghana side of the border is, Shaanxi Gold Underground Mine, and the Historical Nangodi Mine which produced 18,620 ounces of gold from 23,600 tonnes, at an average of approximately 23.9 g/t Au during the 1930’s from underground workings exceeding 150m (Ghana Department of Mines records 1938) and across the border into Burkina Faso, the Youga Gold Mine currently owned by Avesoro Jersey (formerly MNG Gold). As of May 2019, Youga’s proven and probable mineral reserves were estimated at 14.74Mt containing 814,900oz of gold grading at 1.72g/t and has recovered a total of over 0.6 million ounces of gold since operations commenced in 2008 and produced 68,407 ounces of gold in 2015 by its precious owners Endeavour Mining The sequence of exploration techniques that discovered Namdini did not follow the usual pattern of modern mineral exploration as work was initiated on a small‐scale mining lease where panning had discovered nuggets. It was thought that no exposure of gold mineralisation would occur in Northern Ghana due to thick younger sedimentary Voltaian rock uncomformably overlaying the Birimian, however, Namdini was discovered where the younger cover ended with a breakaway in the terrain. Once discovered, other contiguous small‐scale licenses were obtained and consolidated into a single license and an RC drilling campaign to test the area was undertaken. To date, some 700 drill holes for approximately 110 kilometres of Resource drilling and 340 drill holes of sterilization totalling 33 kilometres have been completed on the Namdini mining lease. 116,332 Resource samples and 37,007 Sterilisation RC samples have been submitted to SGS‐Tarkwa and Intertek‐Tarkwa for analysis. Regionally, the Namdini Project occurs in Paleo‐Proterozoic Bole‐Nangodi Greenstone Belt of southwest ‐north east trending granite–greenstone belt which host significant gold mineralisation in Ghana and Burkina Faso. Namdini deposit is located in the Northeastern part of Ghana close to the border with Burkina Faso on a major regional shear zone which divides the rock units of the area into Paleoproterozoic Birimian volcanic assemblages to the west and volcaniclastics and metasediments to the east. The volcanic assemblages are comprised of strongly magnetic ultramafics and mafics, mafic basalts and intermediate to felsic dacitic to rhyolitic units. Much of northern Ghana is covered by post‐ 1 Birimian Voltaian Basin sediments and within the Birimian rocks is Namdini at the northern limit of the Voltaian Basin sediments exposure. Locally, Namdini sits on a splay off the major regional Bole‐Bolgatanga shear and is comprised of Birimian volcaniclastics and metasediments with younger Voltaian horizontally bedded sandstones overlying the Birimian assemblages in the far south of the license. The volcaniclastics dip approximately 60⁰W and strike at approximately 010⁰. The units are generally greenish grey in colour and medium‐grained to fine‐grained where unaltered. The mineralised rocks are intensely sheared and have a typical creamy to greenish colouration (silica‐carbonate‐ chlorite‐ sericite alteration) due to intense hydrothermal alteration containing sulphides (pyrite and minor arsenopyrite). The volcaniclastics have been intruded by light‐coloured, coarse‐grained, sulphide‐bearing monzonites/tonalites and are considered to be the heat engine that mobilised these gold‐bearing hydrothermal fluids which have altered and mineralised the volcaniclastics. Gold mineralisation is hosted in intensely altered and strongly deformed volcaniclastics, monzonite/tonalite, diorite and to a much lesser extent, metasedimentary rocks. Structural studies have shown that gold mineralisation occurred late in the initial deformation phase (D1) prior to a second phase of further intense deformation (D2). Fine‐grained gold is strongly associated with sulphides (predominantly pyrite and minor arsenopyrite) which on average is approximately 1% of the rock mass with overall gold recoveries of over 83% (Life of Mine) and 85% (Starter Pit) for the first three years. Structurally, two schools of thought have been proposed; the first states that, foliations produced during D1 and D2 are well developed in the volcaniclastics and metasedimentary rocks and showed a consistent asymmetry with S1 striking acutely clockwise of strike of S2. The S1‐S2 asymmetry indicates the deposit is located in a sinistral D2 shear zone. Alternatively, the deposit may be located on the limb of a fold that is of a scale larger than the deposit. The intense S1‐S2 foliation? Is a product of transposition of S1 and the zones of high strain represent D2 shear zones that have evolved from precursor zones of enhanced S2 fabric development. Foliations are less well developed in the monzonite/tonalite, with most structures represented by quartz ± carbonate vein arrays and silica‐sericite fractures/veinlets. Faults are uncommon in general and in the monzonite/tonalite, faults tend to manifest as zones of enhanced quartz veining or local fracturing. Parasitic folds are common in the core but were not observed in the field. Regional Geology The Namdini gold project is located in northeast Ghana, immediately to the north of the extensive post‐Birimian, Voltaian sediment cover, which dominates eastern Ghana, as shown in Figure 1. The Birimian in Ghana is defined by a series of SW‐NE trending granite‐greenstone gold belts, which are much better exposed in southern and western Ghana, with the gold belts defined from south to north as the Kibi‐Winneba, Ashanti, Sefwi‐Bibiani, Bui, Bole‐Bolgatanga and Lawra (which trends N‐S). Namdini lies to the south of the regionally extensive Bole‐Bolgatanga belt separated from the greenstones by a regionally continuous, intermediate to mafic granitoid complex. There is a possibility that the sequence of rocks at Namdini form part of the north‐western continuation of the Bui Belt. Alternatively, the Birimian rocks at Namdini can be considered to be the southern extension of the Youga greenstone belt in Burkina Faso which are referred to as the Nangodi Greenstone Belt within north‐eastern Ghana. The Birimian gold belts of Ghana have been extensively studied because of their 2 significant gold endowment (Allibone et al 2002a, 2002b, Allibone et al 2004, Fougerouse et al 2013, 2017, Goldfarb et al 2017). In summary, the main lithological groupings in the belts are sequences of sedimentary basins dominated by greywackes and phyllites, overlain by volcanic and sediment sequences of Birimian age, characterised by interbedded mafic to intermediate volcanic flows, felsic to intermediate tuffs and fine‐grained sediments. The various belts are interpreted to be fault bounded, both during their development and post‐deposition. An association of granitic intrusions occurs and have been divided into two types, Belt‐Type and Basin‐Type. Belt‐Type granites are metaluminous, are often tonalitic and are most commonly confined to the Birimian greenstone belts (Allibone et al, 2004). The Basin‐ Type granites are peraluminous with higher potassium and rubidium compared to the Belt‐Type granites and are generally granodiorites. Late stage diorites intrude the existing sequence of lithologies. Much of Northern Ghana is covered by post‐Birimian Voltaian Basin sediments and at Namdini this forms the southern limit of exposure of Birimian rocks. The horizontal Voltaian basin sediments are in clear angular unconformity with the steeply dipping Birimian granite‐greenstone sequence at Namdini. Figure 1: Regional geology of northern Ghana and the location of Namdini Deposit Model The Namdini gold deposit has many characteristics typical of mesothermal Birimian gold deposits in West Africa (Goldfarb et al, 2017). Figure 6 shows the major gold discoveries in West Africa along with 3 the location of Namdini. Gold mineralisation is strongly structurally controlled, with evidence for a protracted, multi‐phase deformation history. Based upon structural observations (Davis and Cowan, 2016), the timing of the gold mineralisation is late in the first phase of deformation after all host lithologies were in place and possibly extended into the second intense phase of deformation. The deposit appears to be located in an oblique, sinistral structure in a regionally extensive deformation zone (Davis, 2016). All host lithologies
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