Impact’s Botswana Uranium Project comprises two Prospecting Licenses covering 1,390.6 sq km (PL123/2008 and PL016/2014) within the uranium province of central Botswana that includes the 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.

Figure 1

Impact’s licences are prospective for uranium deposits hosted by Proterozoic sedimentary rocks and basement rocks similar to the Athabasca and Olympic Dam styles of deposit.

The Red Hills Prospect

Widespread uranium anomalism and associated intense mineral alteration in both the granitic basement and in the unconformably overlying conglomerates and sandstones of the Proterozoic Palapye Group has been identified by Impact at the Red Hills Prospect on PL123/2008 (Figures 2 and 3).

Figure 2. Geology of the Moiyabana-Kodibeleng area.

Figure 3a. Haematite-chlorite altered conglomerates of the Palapye Group from the Kodibeleng area with uranium values of up to 100 ppm eU3O8.

Figure 3b. Uranium-bearing conglomerate from the Athabasca Basin with pervasive haematite alteration.

Very Large Zoned Mineralised System defined at Red Hills

Impact’s maiden drill programme at Red Hills identified an extensive alteration system at least 1.5 km long and 1 km wide comprising multi-metal and mineral assemblages typical of those associated with major Proterozoic uranium deposits.

The alteration comprises intense and extensive deep-red haematite, specular haematite and chlorite developed in basement granite and sedimentary

Significant intercepts from the drill programme were:

RHRC001:32 m at 0.11% Total Rare Earth Elements (TREE) from 85 m; and
56 m at 0.1% TREE and 16 ppm U3O8 from 166 m;
RHRC002:10 m AT 0.1% TREE from 20 m; 13 m at 25 ppm U3O8 from 115 m; and
15 m at 20 ppm U3O8 from 189 m;
RHRC003:72 m at 0.1% TREE and 11 ppm U3O8 from 25 metres;
RHRC008:97 m at 0.11% TREE and 11 ppm U3O8 from 105 metres;
RHRC009:17 m at 0.14% TREE and 13 ppm U3O8 from 55 m; and
31 m at 0.1% TREE from 86 m;
RHRC010:32 m at 0.13% TREE and 10 ppm U3O8 from 45 m;
RHRC011:48 m at 0.13% TREE from 36 m; and
31 m at 15 ppm U3O8 from 111 m;
RHRC014:57 m at 0.1% TREE from surface, including
24 m at 0.15% TREE and 20 ppm uranium from 6 m; and
12 m at 0.1% TREE from 214 metres.

These intercepts are in part coincident with similar thick intercepts of anomalous silver, lead, zinc and other metals.

The alteration zone contains a central elongated core of very intense specular haematite alteration that is up to 100 m thick, 400 m wide and at least 1.5 km long and is a largely constrained regional fault zone that extends for at least 10 km along strike within Impact’s licences (Figure 4).

The analytical data and mineral alteration studies have shown that the alteration zone comprises an Upper Zone and Lower Zone, both of which thicken towards the east (Figures 4 and 5):

The Upper Zone is developed mainly in Proterozoic sandstones of the Palapye Group, is up to 50 m thick and contains anomalous copper, silver, lead and zinc associated with strong sericite alteration.

The Lower Zone is developed mainly in Proterozoic conglomerates beneath the sandstones as well as in fault breccias in underlying basement granite and granite gneiss of the Mahalapye Complex. The Lower Zone is at least 100 m thick and contains anomalous REE’s (in particular lanthanum and cerium) together with uranium. It is characterised by intense potassium feldspar and specular haematite alteration. In addition quartz-carbonate-fluorite veins have been intersected.

Implications for Exploration

All of the work reported here has very important implications for the uranium potential of Impact’s licences in Botswana. The company’s initial concept for the presence of Proterozoic-age unconformity-related deposits has been re-inforced with multiple avenues of evidence: the mineral alteration assemblages, the nature of their host-rocks, the altered fault breccias and the regional fault control, and the thick drill intercepts with anomalous Rare Earth Elements and other metals (Figure 6).

Unconformity-related deposits of Proterozoic age occur in two global regions: the Athabasca Basin of Canada, and the Pine Creek Orogen of northern Australia. Together they contain six of the 17 largest uranium deposits in the world and have ore grades that are measured in the range of 0.1% to 22% (at McArthur River in Canada). The Mahalpye Complex identified by Impact in Botswana has a similar aerial extent to the Athabasca and Pine Creek regions.

Further work programmes, which will include further drilling at Red Hills, are being prepared.

Figure 4.

Figure 5.

Figure 6. Exploration model for Proterozoic unconformity-related uranium deposits.

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.

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.