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Kavango Resources - Strong evidence of metal sulphides in the KSZ

RNS Number : 9762C
Kavango Resources PLC
23 October 2020
 

PRESS RELEASE

 

23 October 2020

KAVANGO RESOURCES PLC

("Kavango" or "the Company")

 

Strong evidence of metal sulphide accumulations in the KSZ

 

Kavango Resources plc (LSE:KAV), the exploration company targeting the discovery of world-class mineral deposits in Botswana, is pleased to report further strong evidence that the Kalahari Suture Zone (the "KSZ") may host one or more "Norilsk-style" Copper-Nickel-Platinum Group Metal ("Cu-Ni-PGM") deposits.

Dr David Holwell, of D&D Geoconsultants, has completed a significant update to the Mineral Systems Review (first published on 29 April 2020) (the "Review"). Dr Holwell is Associate Professor of Geology at the University of Leicester and is a leading authority on the development of Cu-Ni-PGM sulphide deposits associated with magmatic plumbing systems.

Dr Holwell conducted a mineralogical study and laboratory analysis of rock samples (the "Rock Samples") taken from the Company's November 2019 drill campaign on the Hukuntsi section of the KSZ and the Canadian sponsored Kalahari Drilling Programme (1983). The Review makes several key conclusions.

Specifically, the occurrence of "primary magmatic sulphides" in the thick "gabbroic sills" (>50m thick) of the KSZ (announced on 8 September 2020), combined with strong evidence of "sulphur saturation" and the presence of "cumulate rocks", suggests that "metal sulphides" may have accumulated in trap zones in sufficient quantities to form mineable mineral deposits.

This is an extremely important step forward in advancing Kavango's understanding of the KSZ.

There is now compelling evidence that the KSZ experienced similar geological conditions as those that led to the formation of giant Cu-Ni-PGM massive sulphide deposits at Norilsk (Siberia), Voisey's Bay (Canada), Raglan (Canada), Jinchuan (China) and the Thomson Nickel Belt (Canada).

 

A full description and glossary of terms is provided below.

The Company has also produced a short video, which shows how magmatic sulphides might have accumulated in trap zones in the KSZ to form massive sulphide deposits:

https://twitter.com/KavangoRes/status/1316004057895645186?s=20 

 

Highlights

v In the Review Dr Holwell has concluded:

-    There is now strong evidence that sulphur rich country rock was incorporated into the mafic magma as it intruded into Karoo sediments below the surface (as at Norilsk)

-    This almost certainly led to the development of "sulphur saturation" making the segregation of metal sulphides into a heavy immiscible sulphide liquid more likely

-    This does not seem to have occurred in the thinner sills (<20m thick) where cooling and crystallisation took place quickly.

-    In the thicker sills (>50m thick), slow cooling of the magma encouraged the formation of "cumulate textures" (large silicate crystals in a fine-grained matrix)

-    The Rock Samples from the thicker sills show clear evidence of the development of primary magmatic sulphides in gabbroic cumulate rocks

-    As the sills cooled, the heavy metal sulphides would have sunk through the cumulate rocks to accumulate in trap zones to form massive sulphides.

-    The primary metal sulphides include pyrrhotite (FeS), pyrite (FeS2) and chalcopyrite (CuFeS2).

-    Iron and copper sulphides appear to be in equal proportions.

-    The presence of magmatic sulphides in the upper levels of the thicker sills strongly indicates that the accumulation of massive sulphides may have occurred in trap zones or at greater depths.

v Dr Holwell will now oversee the use of an electron-microprobe to test for the depletion of Nickel in the Rock Samples

v In parallel, Kavango will apply the conclusions of Dr Holwell's updated Review to the Company's 3D Geological Model of the KSZ (the "Model), announced on 8 September 2020

-    The goal will be to identify high-priority targets ("trap zones") for further field exploration and drilling

 

Michael Foster, Chief Executive Officer of Kavango Resources, commented:

"Dr Holwell's latest Review provides further strong evidence that Kavango is on target for a major base metal discovery.

We are getting extremely close to validating our entire exploration hypothesis for the Kalahari Suture Zone.

We will soon confirm our highest priority targets for the next phase of field exploration and will aim to begin the ground-based EM surveys before the end of the year. This will lead to drill target selection and a drilling programme in 2021.

My thanks and congratulations to all of Kavango's geologists, geophysicists and field staff who have done such a fantastic job over the last few months analysing and interpreting significant volumes of exploration data."

 

The Updated Review

In his "Mineral Systems Review of the Kalahari Suture Zone Project" (April 2020), Dr Howell outlined a number of important attributes of magmatic Cu-Ni-PGM deposits that, if present, would represent strong support for the development of magmatic sulphide deposits.

There is now strong evidence that sulphur rich country rock was incorporated into the mafic magma as it intruded into Karoo sediments below the surface (as at Norilsk).

This almost certainly led to the development of "sulphur saturation" making the segregation of metal sulphides into a heavy immiscible sulphide liquid more likely.

This does not seem to have occurred in the thinner sills (<20m thick) where cooling and crystallisation took place quickly. in the thicker sills (>50m thick), slow cooling of the magma encouraged the formation of "cumulate textures" (large silicate crystals in a fine-grained matrix).

The samples from the thicker sills of the KSZ show clear evidence of magmatic sulphides in gabbroic cumulate rocks.

These sulphides include:

-    Primary pyrite (FeS2)

-    Primary Pyrrhotite (FeS)

-    Primary Chalcopyrite (CuFeS2)

Iron and copper sulphides appear to be in equal proportions, while Nickel sulphide (e.g. pentlandite) was not seen, possibly due to its very fine grain size.

The presence of these primary sulphides confirms that a metal sulphide liquid was able to segregate and that copper was one of those metals.

The presence of disseminated magmatic sulphide in the upper levels of the thicker sills strongly indicates that the accumulation of massive sulphides may have occurred in trap zones or at greater depths.

Now that Kavango has received Dr Holwell's updated Review we can confirm the presence of the following geological characteristics in the KSZ:

-    Presence of Cumulate Rocks

-    Sulphur rich xenoliths and interaction of country rocks with the magma

-    Slow cooling textures

-    Sulphide liquid segregation

 

Electron-microprobe of Rock Samples

As previously announced, Kavango has agreed with Dr Holwell to support a research project in conjunction with a MSc student from the University of Leicester entitled "A Comparison of the Mineralogy and Geochemistry of the Mafic Intrusives of the Kalahari Suture Zone (Botswana) and Norilsk/Talnakh (Siberia)".

Work has already started on this project, which will employ advanced analytical techniques available at the University of Leicester. This will include use of an electron-microprobe on drill core samples from the KSZ provided by Kavango.  The purpose of this test will be to confirm Ni-depletion in olivine and pyroxenes. (If these silicate minerals show depletion of Ni, it suggests that the sulphur has "scavenged" the Ni from the melt preventing its incorporation into the silicate lattices).

It is anticipated that this work will provide final confirmation that the KSZ shares all the geological characteristics of other major world-class magmatic sulphide Cu-Ni-PGM deposits.

The Company will provide a further update to the Mineral Systems Review in due course.

 

Drill Target Identification

Using the 3D Geological Model constructed by the Company's in-house geophysics team in collaboration with Mira Geoscience, together with the updated conclusions of the Review, Kavango will now work to confirm its initial high-priority targets for further field exploration.

Specifically, the Company aims to use ground based, high power, low frequency, long loop, EM surveys to identify the thickest parts of the sills, where concentrations of magmatic sulphides may have accumulated to form conductive bodies. 

The identification of such metallic conductors will pave the way towards drill target selection and a major drilling programme in 2021.

 

Further information in respect of the Company and its business interests is provided on the Company's website at www.kavangoresources.com and on Twitter at #KAV.

 

For further information please contact:

 

Kavango Resources plc                                                                                     

Michael Foster

[email protected]

 

SI Capital Limited (Broker)                                                                          

+44 1483 413500

Nick Emerson

 

 

Note to Editors:

THE KALAHARI SUTURE ZONE

Kavango's 100% subsidiary in Botswana, Kavango Minerals (Pty) Ltd, is the holder of 12 prospecting licences covering 8,324.7km2 of ground, including 10 licences over a significant portion of the 450km long KSZ magnetic anomaly in the southwest of the country along which Kavango is exploring for Copper-Nickel-PGM rich sulphide ore bodies. This large area, which is entirely covered by Cretaceous and post-Cretaceous Kalahari Sediments, has not previously been explored using modern techniques.

The area covered by Kavango's KSZ licences displays a geological setting with distinct similarities to that hosting World Class magmatic sulphide deposits such as those at Norilsk (Siberia) and Voisey's Bay (Canada). 

The Norilsk mining centre is about 2,800km northeast of Moscow and accounts for 90% of Russia's nickel reserves, 55% of its copper and virtually all of its PGMs. Kavango's licenses in the KSZ display a geological setting with distinct geological similarities to the magmatic sulphide deposits at Norilsk. Magma plumbing systems are a key feature of these deposits.

KSZ DEFINITIONS

Cumulate rocks: A feature of some intrusive igneous rocks in which the crystallisation of some minerals occured before others. This produces a rock composed of large crystals (cumulus crystals) enclosed within a fine grained (inter-cumulus) phase. The unevenness in the rate of crystalisation can lead to layering of mineral phases during cooling. In mafic (gabbros) or ultra mafic magmas, the first minerals to crystallise are usually the heavier, iron rich minerals which tend to sink to the bottom of the magma chamber.

Gabbro/gabbroic: A coarse grained, medium to dark coloured rock, formed from the intrusion of mantle derived molten magma into the earth's crust. Gabbroic rocks (or "gabbros") are formed as the molten magma crystallizes and cools.

Gabbroic sills: Relatively thin, planar, horizontal bodies of solidified gabbroic magma that intruded into layers of sedimentary rock whilst still molten.

Karoo: The Karoo System covers 1.5 million km2 of the semi-desert region of Southern Africa. Rocks in this system formed 180-310 million years ago.

Magma plumbing system: Magma plumbing systems are composed of stacked horizontal sills connected to each other via vertical dykes.  A continuous flow of magma (containing "free" sulphur) through a magma plumbing system may have allowed the accumulation of metal sulphides in certain trap sites within the sills. This is because metal sulphides are heavy and tend to sink to the bottom of magma. Over time, accumulations of metal sulphide could have led to the formation of economic deposits of Copper-Nickel-PGMs. 

Massive sulphide: When a deposit consists almost entirely of sulphides it is termed "massive". When it consists of grains or crystals of sulphide in a matrix of silicate minerals, it is termed "disseminated".

Magmatic sulphide: Primary sulphide minerals found in igneous rocks and formed within a cooling and crystallising magma from sulphur and metal ions in the melt. Deposits of sulphide mineral concentrations in mafic and ultramafic rocks, derived from immiscible sulphide liquids. To view a video of how metal/magmatic sulphides form please visit -

https://twitter.com/KavangoRes/status/1316004057895645186?s=20 

Olivine: an olive-green, grey-green, or brown mineral occurring widely in basalt, peridotite, and other basic igneous rocks. It is a silicate containing varying proportions of nickel, copper, iron and other elements. Depleted Cu-Ni-PGM readings in olivines are an encouraging exploration vector, when search for major Cu-Ni-PGM deposits.

Primary sulphides: Are sulphide complexes (or crystals) that form as the magma cools and are composed of elements that are present at the time of initial crystallization. Secondary sulphides may form after the magma has solidified either by the introduction of new elements into the rock or by re-mobilising elements already present through changes in pressure, heat etc.

Pyrite: A shiny yellow metallic-looking mineral composed of iron sulphide (FeS2).

Sulphide mineralisation: If there is sufficient sulphur in the molten magma, it will tend to combine with metals (Cu, Zn, Ni, Co, Pb, PGEs etc.) to form metal sulphide complexes, which may coalesce to form massive sulphide deposits. If the melt is sulphide poor, the metals will be taken up into the silicate minerals that form as the magma cools and will not usually form economic deposits.

Xenolith: A xenolith is a piece of rock trapped in another type of rock.  Usually, a xenolith is a piece of country rock incorporated into molten magma whilst it is intruding the earth's crust. 

 

 

 

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