|BOTSWANA URANIUM PROJECT (Impact 100%)|
Impact's Botswana Uranium Project comprises approximately 30,000 sq km of Prospecting Licenses containing significant strike extensions to the host rocks found at the nearby Letlhakane Uranium Project owned by A-Cap Resources Limited (Figure 1). A-Cap have reported an Inferred Resource of 261 million lbs of U3O8 at an average grade of 150 ppm (100 ppm cut-off) hosted within near-surface calcretes of the Kalahari Group and sedimentary rocks of the Karoo Group. A-Cap has recently commenced a feasibility study into open pit mining and heap leach treatment of the resource.
Impact's licences are prospective for four types of uranium deposit, hosted by:
- calcretes within palaeochannels;
- Karoo sedimentary rocks;
- Proterozoic rocks and sedimentary in basement faults; and
- deposits hosted by Proterozoic leucogranites.
Impact's interpretation of Government-supplied airborne radiometric data covering 75% of Impact's tenements in northeastern Botswana identified several prospective sites with elevated surface uranium responses. This data, together with field reconnaissance, mapping and drilling, led to a discovery at Lekobolo, Morolane, Mosolotsane and Molyabana (Figure 1). All of these are in siltstones and sandstones of the Karoo Supergroup.
Impact estimates that for the area drilled at Lekobolo (Figures 3 and 4) there is a Target Mineralisation (see Note 1) of between 14 Mt and 18 Mt of mineralisation at an average grade range of between 135 and 180 ppm for a contained 4 Mlb to 7 Mlb of U308.
This target is conceptual in nature and it should not be construed as a resource calculated in accordance with the JORC Code.
The Lekobolo deposit would be important as a satellite deposit for an existing mining operation and is currently inadequate for a stand-alone mine. Accordingly resource definition drilling will be placed on hold until circumstances warrant.
Lekobolo: Uranium deposit discovered adjacent to the Letlhakane Project
The Lekobolo Project is within Impact's Licences P116/2008 and P117/2008, 20km south of A-Cap Resources Letlhakane Project and their recent discoveries at Serule West and Serule East (Figure 2).
The Karoo-hosted primary uranium mineralisation at Letlhakane occurs close to the Archaean basement in a fault-bounded sedimentary basin fed by Karoo palaeochannels identified in the radiometric and magnetic data.
The Lekobolo target area comprises the interpreted south western extension of the Letlhakane Project. The area is underlain by Karoo sandstone and siltstone units together with overlying calcrete and gypsum deposits, largely concealed by unconsolidated sand and soil. This has also diminished or completely blanketed any radiometric response from the underlying rocks.
However an east-west trending area up to 12 km long and 3 km wide contains elevated uranium responses, up to 26 ppm U3O8, in the airborne radiometric data. (Figure 2).
During the 2009/2010 year Impact identified reverse circulation and hollow stem auger core drilling at the largest soil anomaly lead to the discovery of the Lekobolo uranium deposit.
Uranium mineralisation occurs as broad, largely horizontal, layers from surface down to about 45 m depth and covering an area of about 2,000 m by 700 m (Figures 3 and 4). Mineralisation occurs mainly as carnotite hosted by altered and weathered carbonaceous mudstone, sandstone and conglomerate within a Karoo palaeochannel. Higher grade zones occur in a few places (Figures 4 & 5).
Five core holes were drilled close to selected RC holes in order to obtain information about the geology and continuity of mineralisation. Two of these core holes, although reporting significant results, show a poor correlation with their adjacent RC holes and indicate further drilling will be required to establish continuity of the high grade zones for the purposes of resource definition.
A-Cap Resources Ltd has reported that metallurgical test work on the Letlhakane mineralisation using radiometric sorting and screening can pre-concentrate the plant feed, significantly reducing processing costs. The higher grade narrower zones evident in the drill results at Lekobolo, supported by the portable XRF analyses on core (Figure 5), suggest that similar pre-concentration may be possible for the Lekobolo mineralisation.
There is potential for further discoveries close to the Lekobolo deposit. Several untested soil and airborne radiometric anomalies within the Lekobolo Prospecting Licence to the north of the existing drilling are under review for drilling as part of a future campaign (Figure 2).
Ikongwe and Shoshong: 80km of calcrete drainage channels
Impact’s 100% owned Shoshong and Ikongwe Prospects are located 150 km north of Gaborone in eastern Botswana and 150 km south of the large Letlhakane uranium project (A-Cap Resources Limited) (Figure 1).
The Shoshong and Ikongwe Prospects are linear zones of low-lying topography with weak to modest response in the airborne radiometric data and extensive calcrete outcrops. The area is underlain by Proterozoic metasedimentary and granitic rocks that are covered in most places by younger Kalahari rocks, sand and calcrete.
The linear zones are interpreted as ancient drainage palaeo channels filled with calcreted Kalahari sediments that are prospective for very large calcrete-hosted uranium deposits such as those at Yeelirrie in Western Australia (BHP Billiton Limited) and Langer Heinrich in Namibia (Paladin Energy Limited).
There has been no previous drilling for uranium in the Shoshong and Ikongwe areas.
The soil surveys at Shoshong and Ikongwe comprised 1436 samples taken at 500 metre intervals along lines one kilometre apart, and covering an area of 465 sq kilometres (Figure 6). The samples were analysed for uranium by the MMI-M method at SGS Laboratories in Perth.
At Shoshong the soil results have defined a very large area up to 35 km long and 7 km wide that trends from north to south and south west across Impact’s Prospecting Licence. There are elevated uranium-in-soil values of between 4 and 15 times background (Figure 6).
Within this large area there are five targets for further work defined by uranium responses greater than about 10 times background. These cover about 20 square kilometres of Impact’s Licence area (Figure 6). Two of these areas define in part a prominent NNE to SSW trending linear zone that is at least 12 km long and occurs within a calcrete drainage channel. The anomaly is open to the north.
At Ikongwe the soil results have defined two areas, each about 10 to 12 square kilometres in size, in the north and south of the Prospect area that contain elevated uranium-in-soil values of between 4 and 12 times background (Figure 6). These two areas contain very recent alluvium and this may have subdued the soil geochemistry responses.
In the northern area at Ikongwe there are two targets for immediate further work defined by uranium responses greater than about 6 to 10 times background. These anomalies are open to the north.
The uranium-in-soil results at Shoshong and Ikongwe are similar to those over Impact’s 40% owned Nowthanna uranium deposit in Western Australia. They are significant and support the high prospectivity for calcrete-hosted uranium mineralisation within Impact’s extensive ground holdings in Botswana.
Follow up field checking and selection of specific areas that warrant drilling is in progress.
Moiyabana Prospect: Proterozoic granitic basement and sedimentary rocks
At Impact’s Moiyabana Prospect, close to the Morolane and Mosolotsane discoveries (Figure 7), field checking of a 3 km by 1 km airborne uranium anomaly returned surface uranium anomalism of up to 470 ppm eU3O8* within granitic gneiss and migmatite. Such results from Proterozoic granitic rocks in Botswana have not been reported before and are known (and mined) at the World Class Rossing uranium mine (Rio Tinto Ltd) in adjacent Namibia.
In Botswana these rocks form a basement to the mineralised Karoo and Kalahari sedimentary rocks which have been the primary focus of Impact’s uranium search in Botswana.
During 2010 Impact drilled three holes within this anomaly and these returned broad intersects of mineralised granitic gneiss and migmatite including 4.2 m at 320 ppm eU3O8 from 35 m down-hole in fresh rock. The mineralisation is hosted by chlorite schist, indicative of a shear zone or fault, and is open at depth and along strike. A thicker intercept was16 m at 115 ppm eU3O8 from only 2 m depth (Figure 8).
In addition field checking of a 60 km by 30 km area between Moiyabana and Kodibeleng has identified many areas, all within Impact’s Licences, with widespread uranium anomalism and associated intense mineral alteration in both the granitic basement and in the unconformably overlying conglomerates and sandstones of the Palapye Group (Figure 9).
These rocks are Proterozoic in age and much older than the Karoo sedimentary rocks which host the large Letlhakane deposit 150 km north east of Moiyabana.
Significant Exploration Potential
The basement-hosted drill discovery at Moiyabana together with the widespread uranium anomalism and alteration in the Palapye Group sedimentary rocks have significant implications for uranium discoveries in Botswana by increasing the scope of the search to new types of deposits.
The newly discovered uranium mineralisation has geological characteristics similar to those at and around the unconformity-related and high grade uranium deposits in Proterozoic rocks in the Athabasca Basin (Canada) and the Pine Creek Orogen (Australia) (Figure 10).
In the Proterozoic Athabasca Basin the deposits occur within both the basement gneisses, commonly within chlorite-bearing faults and shear zones, and in the overlying sedimentary rocks, generally haematite-altered sandstones and conglomerates (Figures 9a and 9b).
These deposits are high grade and very attractive exploration targets. The uranium mines of the Athabasca region collectively produce about 20% of the World’s uranium. The uranium deposits mined historically, or currently being mined, range in size up to 450 Mlbs U3O8 at an average grade of up to 19% eU3O8, as at the large Cigar Lake Mine.
These types of uranium deposits have only been identified in Canada and Australia, so Impact's work has uncovered a whole new province with very significant exploration potential. Impact holds about 18,000 sq km of this region for the right to explore for uranium.
Impact is the first mover for exploration for this type of deposit in Botswana and has recently been granted a further 9,000 sq km of Prospecting Licences over this region.
An extensive programme of reconnaissance field checking and mapping together with the limited drilling at Moiyabana, has identified a much larger scenario for uranium exploration in Botswana.
This is an important development for Impact as Proterozoic unconformity-related deposits are high grade and attractive exploration targets. Six of the top 18 deposits in the world are in this category.
Impact has scoped exploration programmes requiring significant expenditures and is considering a number of ways to accelerate exploration of the Company’s large ground holdings.
The Company is continuing its systematic programme of target definition for further drilling at various locations.
Morolane and Mosolotsane
The Morolane and Mosolotsane Projects are located about 150 km south west of the Letlhakane Project close to the town of Kodibeleng (Figure 1). They were identified as modest radiometric anomalies in Government regional airborne data and field checking showed that most of the anomalism is associated with Karoo sedimentary rocks, as at the Lekobolo and Letlhakane deposits.
Soil geochemisty results at Morolane defined numerous uranium-in-soil anomalies up to 10 km long and 2 km wide. The largest of these anomalies covered an area of Karoo sedimentary rocks and was selected for drilling together with one other area. Drilling of these two areas has produced thick drill intercepts of modest grade uranium within carbonaceous mudstone and sandstone. Interpretation of the drill logs and field mapping indicate that both Prospects occur in the upper reaches of a Karoo palaeochannel. Accordingly further exploration work is warranted along these palaeochannels to the west and north west towards larger Karoo sedimentary sub-basins.
The Karoo discoveries at Lekobolo, Morolane and Mosoltsane attest to the very high prospectivity of Impact’s Botswana Uranium Project. They indicate that the geological processes that formed that formed the large deposit at the Letlhakane Project were active in many places elsewhere in the Karoo sedimentary sequences.