The Kalahari Copper Belt, or “KCB”, has emerged as an important global copper and silver discovery hub in Botswana.
It’s already home to large discoveries being developed by companies like Sandfire Resources (ASX: SFR) and Cobre Resources (ASX: CBE). And with the entire region now staked, those with a significant footprint are at a considerable advantage when it comes to making the next round of economic deposits.
Despite this, Kavango Resources (LSE: KAV) believes a vast portion of the KCB’s mineral wealth remains overlooked. Thanks to its pioneering use of CSAMT surveys, however, the company believes it’s on the verge of changing this for good…
The KCB conundrum
To understand the progress being made by Kavango across its KCB licence package, the best place to start is with what might be termed as the area’s “exploration conundrum”.
In short, rock layers underlying the KCB do not simply run in perfectly horizontal lines like the layers of a cake. Instead, they “fold” in undulating waves as a result of tectonic activity.
The result is they cycle between domes peaking closer to the surface called “anticlines” and curved troughs called “synclines”. The visual below from Radford University helps to visualise this
KCB mineralisation is controlled by an area where two of these rock layers meet, known as the “D’Kar/Ngwako Pan contact zone”. The D’Kar is the younger and shallower of the two rock layers, and is up to 1,500m thick. It overlies the older and deeper Ngwako Pan rock, which reaches a thickness of up to 2,000m.
The D’Kar/Ngwako Pan contact zones form what are known as “redox boundaries”. When this redox boundary is cross cut by a geological process of some kind (usually on the limbs, or edges, of synclines and anticlines), it can result in the “brecciation”, or cracking, of rock. Superheated fluids can then pass through these cracks and deposit metal ions which can accumulate over time into economic mineral deposits due to a lack of “oxidation” (and, in turn, rusting).
Now, the working theory to date is that this mineralisation typically forms when brecciated D’Kar/Ngwako Pan contact sits under or around an anticline in the KCB. It makes sense–these areas are where the bulk of discoveries have so far been located in the region because they are relatively shallow and easy to drill.
However, Kavango now believes this could actually be a case of confirmation bias in action.
Instead, the company argues that economic mineralisation may also be present in brecciated D’Kar/Ngwako Pan contact zones located on synclines. However, regional exploration has not yet been able to develop to the stage where investigating this potential has been possible.
After all, Kavango knows the D’Kar rock is 1,500m thick in places. It also knows that the predominant technology for mapping the stratigraphy of the KCB–Airborne Electromagnetic (“AEM”) surveying–is usually only effective down to around 300m.
So, the reality is that it has been extremely difficult to map how deep D’kar/Ngwako Pan contact zone targets are in these deeper horizons. Drilling to find what they might yield, as a result, has essentially been akin to flying blind.
Given how expensive drilling is (not to mention how vast the KCB is), that’s a very easy way to quickly eradicate one’s exploration budget without any useful results. It’s simply been cheaper and easier to go for the “low-hanging fruit” closer to the surface on the anticlines.
Until now, perhaps.
Throughout 2022, Kavango has been working to overcome this historical exploration barrier using Controlled Source Audio Magnetotelluric (“CSAMT”) surveying.
CSAMT itself isn’t new; it’s an established electromagnetic sounding technique that measures where rock layers might be located in the earth’s crust. However, Kavango is the very first company to apply the technical innovation needed to use in the exploration of the KCB.
Indeed, after 10 months of refining & calibrating its collection, processing, and analysis of data, Kavango showed in October that it can now measure stratigraphic contacts in detail down to 4km in the KCB. Now, following an update last week, the company has taken a major step towards proving this could be vital in unlocking the KCB’s full potential.
A significant development
In its update, Kavango revealed that it had completed the interpretation of inversion results for the CSAMT Line 4A survey over it’s PL082/2018 licence in the KCB. This can be seen below, and highlights three points of interest in particular:
First, as Kavango previously highlighted, its neighbour Sandfire allowed the company to extend Line 4A onto its licence and specifically over its Kronos copper occurrence.
The occurrence is known, through drilling, to be hosted in a D’Kar/Ngwako Pan contact zone. So, the clear identification of both Kronos and its surrounding structure on the image’s right offers physical evidence that CSAMT can actually highlight the key control on KCB mineralisation.
Second, Kavango physically encountered the zone of brecciation highlighted on the left side of the image at exactly the depth anticipated (350m) when drilling its latest hole (KCBRD005).
There was no surface expression of this zone on offer. So, the development provides physical evidence that CSAMT on its own can accurately map areas of geological activity in the KCB known historically to lead to mineralisation, aiding drill targeting.
Third, the CSAMT clearly defines a distinct, dipping geological folded syncline across Kavango’s licence linked to an anticline on Sandfire’s where Kronos sits. Given that the two formations have been physically confirmed by drilling–both by Kavango and Sandfire–Kavango is betting it can locate them elsewhere in the KCB.
Kavango’s interpretation of this final point is that the D’Kar/Ngwako Pan contact known to be in place at Kronos may be traced onto the company’s own licence trending to the northwest. Specifically, it believes it could follow the syncline and dip back towards surface near the PL082’s northwest edge.
If this is the case, it would be highly significant.
For one thing, it would mean CSAMT can identify the location and depth of prospective D’Kar/Ngwako Pan contact without drilling. But for another, it would mean the technology can also identify zones where that contact is brecciated, and therefore stands a greater chance of being mineralised.
This would open up a big opportunity–both for Kavango on its own KCB licences, which have historically been underexplored due to deep sand cover, but also in the KCB more generally. After all, existing explorers are likely to be interested in any technology that could unlock previously untouched mineral potential on their own licences.
Kavango is currently working hard to confirm CSAMT’s ability to identify D’Kar/Ngwako Pan contact in this way.
The company has engaged a KCB-experienced local geological contractor to re-log and analyse PL082 drill cores and rock chip samples. Its goal is to confirm the presence of physical and geochemical exploration vectors that could indicate the proximity of a potential mineralising system to the recent drilling.
Pending results, it then plans to drill another hole following the Christmas break that can physically prove the inverted CSAMT data is effective in:
- Identifying the D’Kar/Ngwako Pan contact on the northwest limb of PL082’s syncline;
- Verify interpreted fault structures; and
- Determine if targets are altered and mineralised
We will, of course, have to wait and see what happens. But what is clear is that Kavango could be on the verge of a major exploration breakthrough in the KCB. Indeed, the recent appointment to the company’s board of Jeremy Brett, who has led the firm’s technical efforts in the region this year, speaks measures.
Things could be about to get very exciting for Kavango in the New Year.
Author: Alex Chalk
Disclaimer & Declaration of Interest
The information, investment views and recommendations in this article are provided for general information purposes only. Nothing in this article should be construed as a solicitation to buy or sell any financial product relating to any companies under discussion or to engage in or refrain from doing so or engaging in any other transaction. Any opinions or comments are made to the best of the knowledge and belief of the writer but no responsibility is accepted for actions based on such opinions or comments. The writer may or may not hold investments in the companies under discussion. The author has been paid for the production of this piece by the company or companies mentioned above.
