Osino continues to identify, and aims to further consolidate, areas of key regional structural and stratigraphic targets in this part of the Damara Belt.
Osino regional exploration is focused on a number of specific regional fault, fold and lithological targets with similarities to Otjikoto, and which occur along similar trends while also fitting the general targeting criteria of the orogenic gold model followed by the Company.
History of B2 Gold’s Otjikoto Gold Mine
The Otjikoto gold deposit was discovered in 1996 by Avdale Namibia, when they drilled a prominent magnetic anomaly during a regional base metal exploration programme in an area of flat, featureless calcrete covered scrub. After the discovery, areas of similar stratigraphy to the east and south of Otjikoto were explored using geophysical methods, specifically airborne magnetic and electromagnetic surveys, of which the most prominent anomalies were tested with wildcat diamond holes and in some cases with RAB drilling. None of the geophysical targets drilled were positive and Avdale relinquished the Otjikoto East area in 2010.
The Otjikoto deposit has now been demonstrated to host a historical resource in excess of 3 million ounces and growing with mineralisation found to be largely hosted by schists belonging to the Okonguarri Formation. Gold mineralisation is found just below the contact with the marbles of the Karibib Formation.
These stratigraphic contacts have therefore focused Osino’s exploration to date; however, the uppermost Kuiseb Formation – which forms so much of the host rock stratigraphy at Twin Hills – underlies parts of the license areas and makes valid additional targets to the planned exploration during 2021.
This basket of projects comprises ten licenses covering approximately 420km2 to the southwest of Otjikoto (Etekero), and three licenses adjacent and to the east of B2 Gold’s Otjikoto mine with a total area of 972 km2. These eastern licenses (Otjikoto East) are contiguous and cover the eastern strike extension of the Otjikoto gold deposit.
Osino started regional work at Otjikoto East in October of 2017, with initial reprocessing of the regional magnetic data to assist with lithological mapping under the calcrete cover, and remote sensing regolith mapping to best constrain the geomorphological setting of the geochemical results. High priority areas were selected on the basis of stratigraphy and structural complexity and a campaign of calcrete and termite mound sampling was initiated.
Calcrete sampling has been highly successful in western Australia and has led to the discovery of gold deposits under cover. Anthill sampling has been successful in exploring for gold in Zimbabwe as well as West Africa. These methods of sampling have been applied by the Company and both calcrete sampling as well as anthill sampling have been successful leading to the discovery of a number of gold anomalies. Further geological interpretation has been combined with magnetic mapping to identify large-scale, potentially gold fertile structures as well as the enabling a delineation of the prospective stratigraphy.
As the Otjikoto East region has very limited outcrop and the interpreted geology is essential to prioritize and direct activities on the ground, magnetic mapping has become crucial in identifying the large-scale, potentially gold fertile structures as well as the prospective stratigraphy.
Given the positive results received from this area to date it will be prioritised for further work in 2021 with the following anomalies scheduled for follow up mapping, geochemical sampling and drilling later this year.
Otjikoto East Follow-up Targets
These results have outlined a number of targets for this year’s exploration programme.
Fairview: This was located as multiple gold anomalies in anthill samples adjacent to an interpreted dome structure. Subsequent pitting and rock chip sampling of limited quartz veins produced two positive assays of 1.16 and 0.90 ppm gold, along with anomalous silver and copper. This is regarded to be a priority target for follow up and indeed is the first new gold mineralization discovered in this region since the Otjikoto deposit. During 2021 it is planned to complete RC and DD drilling of the identified mineralized quartz veins as well as the identified geochemical and magnetic anomalies.
Platform: A linear gold anomaly adjacent to the crustal scale lineament dividing the basin sediments to the south (Northern Zone) and the platform margin carbonates to the north (Northern Marginal Zone). The Devon target is considered part of this and further sampling and mapping over and adjacent to the major structure as well as percussion drilling of these anomalies is planned.
Omahona Fold: This is a large-scale, low-grade gold anomaly in calcrete along the folded contact between schists and marbles. Follow-up surface/bedrock sampling is planned.
Omagonde: A low-level gold and silver anomaly was located within calcrete in the northwest corner of the project. Omagonde is planned for follow-up surface and bedrock sampling in 2021.
Gaidaus: This is an east–west striking gold anomaly in calcrete, along an interpreted thrust fault between schists and marbles. The historical Okurusu copper – gold occurrence (a small gossan in marble) is adjacent and follow-up surface/bedrock sampling is planned.
Etekero is an anthill anomaly that was discovered by Teck Resources but was never followed up. Osino acquired the license in 2018 and followed up Teck’s sampling results in order to better define the anomaly. A short bedrock, percussion drill program was completed in Q2 2019 on the Etekero anthill gold anomaly, completing a total of 1,340m of shallow drilling in 93 holes. Three lines about 400m apart were drilled with holes at 25m spacing along the lines.
The assay results from the bedrock sampling indicate a zone of anomalous gold striking northeast parallel to the Omaruru lineament. This anomaly will be followed-up with diamond drilling and further anthill sampling to extend the anomaly to the north and south.
Other Otjiwarongo Regional Targets
The Otjiwarongo Regional Exploration Project is made up of six licenses with a surface area in excess of 3,000km2 situated in central Namibia. The licenses lie roughly between the Company’s Karibib and Otjikoto East Projects. In addition to these licenses, Osino has also applied for another two EPLs which, if granted, would add approximately 1,580km2 to the Company’s ground holding in this large project area.
During 2020 only limited work has been possible, however, sampling and mapping over priority areas was initiated. A total of 6799 samples were collected including 4297 soil, 1456 termite hill and 1046 calcrete samples. These samples are being processed and analysed and once results received will inform plans for the 2021 programme.
Work already scheduled for 2021 includes diamond drilling and further anthill sampling at the Etekero Anthill Anomaly, and the continuation of sampling over priority areas based on structure and lithology.
Work Planned for 2021
The work program for 2021 will include:
- Continuation of sampling program over priority areas based on structure and lithology – approximately 15,000 samples in total
- Follow-up sampling and/or bedrock drilling of gold anomalies
- Follow-up of initial shallow percussion bedrock drilling of the Etekero Target.
Osino continues to identify, and aims to further consolidate, areas of key regional structural and stratigraphic targets in this part of the Damara Belt. The licenses are focused on specific regional fault, fold and lithological targets with similarities to other gold deposits and occurrences found in Namibia, while also fitting the general targeting criteria of the orogenic gold model followed by the Company.