Kavango’s main focus in the southwest of Botswana is the north-south trending 450km x 50km magnetic anomaly known as the Kalahari Suture Zone ("KSZ").
Analysis of previously drilled core suggests that the magnetic anomaly is due to mafic intrusions, many of which are considered to be feeder zones to the vast basalt lava flows which once covered much of southern Africa. These intrusions display distinct similarities to the feeder zones that host the giant Norilsk deposits in Siberia. The project area covers about two thirds of the KSZ as well as unexplained magnetic anomalies on its eastern flank.
Two helicopter-borne electromagnetic surveys covering a total of 4,070 line-kms over the northern part of the KSZ near the small town of Hukuntsi were completed in September 2018 (Phase 1) and February 2019 (Phase 2) by Geotech from Canada and SkyTEM from Denmark, respectively.
SkyTEM’s innovative new generation 312 HP (High Power) technology achieved exceptional depth of investigation (average 400m) beneath the Kalahari sand cover and Karoo sediments due to the high moment (HM) mode with high current and low base frequency of 12.5 Hz. This system has only been on the market since 2017 and therefore represents a major advance in AEM systems.
Aarhus Geophysics, Kavango’s independent geophysical consultant, has produced detailed 3D electromagnetic and magnetic models of the area flown by SkyTEM. This includes interpreted lithological units; magnetic susceptibility models and conductive targets. The model identifies conductors closely associated with gabbroic intrusives and faults. The modelling allows Kavango to view each line flown as a vertical section with depth penetration down to over 700m in some cases. It also provides for horizontal “slicing” at any depth. This enables Kavango’s geologists to move from line to line, at any depth, to view the conductive targets and their associated host lithologies.
Two example cross sections are shown below. The elevation above sea level is shown on the left axis at approx. 1,100m above sea level, and the bottom of the section is approx. 750m above sea level (and importantly beneath the Kalahari sand and Karoo sediment cover). The gabbro intrusive rocks are clearly visible penetrating into the Karoo sediments.
Geology of SW Botswana with location of Kavango’s prospecting licences on the N-S trending Kalahari Suture Zone & Ditau.
X-Section – Line 100502 in PL365/2018
X-Section – Line 104301 in PL163/2012
Numerous conductive zone anomalies have now been identified. These are currently being followed up on the ground and detailed geophysics and geochemistry are enabling priority targets to be identified ahead of drilling.
Plan view of Phase 2 AEM survey modelled by Aarhus Geophysics Ltd. The image is a horizontal slice at 240m depth below surface showing EM anomalies. Dots represent single line anomalies whereas linear shapes are over several lines. Each horizontal line is 500m apart.