Otjikoto East Regional Exploration
Otjikoto East Exploration
The exploration area is within a zone of convergence of major tectonic boundaries, likely to produce increased hydrothermal fluid flow during and immediately after the Damara orogeny. This setting is ideal for orogenic style gold mineralisation. Detailed structural interpretation from aeromagnetics and ground mapping will be used to prioritise nodes of maximum fluid flow.
Stratigraphic Column for Damara Lithologies in Otjikoto East Area
The Otjikoto deposit is situated just below the contact between the Karibib marbles within schists (after shale, greywacke and limestone) belonging to the Okonguarri Formation (Arandis Formation equivalent). The licences also cover turbidites belonging to the Kuiseb Formation within a regional syncline.
The Project is situated within the Northern Zone of the Damara Supergroup in central Namibia to the south of Tsumeb. The Damara Supergroup is Neo-Proterozoic in age and is comprised of continental margin carbonates and silts which grade into turbidite sequences representing continental shelf and basin deposits. The Damara underwent a major orogenic event at 550 – 500Ma when the sea was closed along a series of major ENE structures. Hydrothermal fluid movement produced widespread gold mineralisation within the carbonates and schists. There are two major producing gold mines within the Damara and several well-known smaller deposits which have been mined or evaluated in the past including Ondundu, Onguati, Sandamap and Epako.
The Otjikoto Gold Deposit was discovered in 1999 by Anglovaal’s local subsidiary Avdale, when they drilled a prominent magnetic anomaly during a regional base metals exploration programme. After the discovery, the area of similar stratigraphy to the east and south of Otjikoto was explored for gold by Avdale. The region is largely covered by calcrete and in certain areas by calcrete and wind-blown sand. Exploration was therefore driven by geophysical methods – primarily aeromagnetics and electromagnetics. The most prominent magnetic and electromagnetic anomalies were tested with wildcat diamond holes and in some cases with RAB drilling. None of the geophysical targets were positive and Avdale relinquished the Otjikoto East area in 2010.
Work Completed by Osino to Date
Osino started regional work on the Otjikoto East licence (EPL5897) in October of 2017. Initial work involved regolith mapping and reprocessing of the regional magnetic data to assist with lithology mapping under calcrete cover. The highest priority area was selected for calcrete sampling and termite mound sampling where required. Calcrete sampling has been highly successful in Western Australia and has lead to the discovery of several gold deposits under cover. This technique has not been tested in Namibia until now. In November 2017, a field team started collecting calcrete and termite hill samples on EPL5897. These samples are being sent for ultra-low detection limit assay at Genalysis in Perth – the leading experts on calcrete analyses. Traditional geological mapping is being carried out where possible.
Work Planned for 2018
Osino believes that the area under licence has not been adequately explored and plans to carry out regional sampling programmes with a combination of calcrete, termite mound and traditional soil sampling. Samples will be analysed by ultra-low detection assay and anomalies followed up with detailed sampling, ground geophysics and drilling. Exploration will initially focus on the 58 km strike length of the historically prospective transition between Okonguarri siliciclastics and the overlying Karibib carbonates. In addition, there are two regional scale structures which pass through the licence area which may have provided pathways for hydrothermal fluid flow.
The calcrete and termite mound sampling initiated at the end of 2017 will continue during 2018 with the addition of a second field team in order to accelerate the sampling rate. Coherent gold anomalies will be tested under the calcrete using an auger or RAB drill during H2 of 2018.