Namibia - Mile 72 Uranium
Figure 1 - The Mile 72 project area (EPL3308).
The Mile 72 Uranium Project is an exploration project on the coast of Namibia, north of the city of Swakopmund (Figure 1). Some of the world’s highest uranium grades were recorded in outcrops and in shallow pits within the project licence area. This high grade surface enrichment, combined with detailed geophysical data and interpretations, have encouraged Metals to target a large primary uranium deposit of a similar style to the Rössing and Husab mines to the south.
Significant advances have been made in the geological understanding at Mile 72 as a result of various drilling programs Results from the September 2013 and June 2014 drilling programs confirmed the existence of alaskite-hosted uranium mineralisation at Mile 72.
The program identified zones of uranium-enriched schist-granite-alaskite rocks with significant strike extent in the upper 85m at Mile72.
A calcrete palaeochannel was identified on the licence in the June 2014 program (secondary Langer Heinrich style of mineralisation). This occurrence is considered promising for the accumulation of surface mineralisation sourced from hard rock sources already identified at the Project.
The drill results for both programs validated the presence of continuous zones of primary uranium mineralisation at Mile 72 in the South East of the licence area.
Drilling programs tested the extensions of previous uranium trends and identified mineralisation under sand cover. The presence of multiple, narrow uranium-enriched horizons within a sequence of schist-granite-pegmatite/alaskite was confirmed by further drilling. These uranium-mineralised zones represent an ongoing opportunity for the southeast of the project to host significant primary and/or secondary uranium mineralisation.
An overview of the drilling to date has facilitated the identification of a number of key geological relationships, the most important of which being the consistency and significant strike extent of the anomalous pegmatite/alaskite zones thus far identified.
At least three zones have been identified in the southeast of the licence from a combination of drilling and trenching. These zones extend for a strike length of between 400m and 1,800m and are open-ended. The drilling was able to confirm the predictable nature of the uranium-enriched zones along strike and at depths of up to 85m below surface. This predictability is of great use in exploration planning and, ultimately, resource estimation.
This strong continuity of the identified mineralised zones is highly encouraging. Although the zones intersected thus far appear narrow and the grades variable, there is scope for wider, duplicated zones to be identified, as well as for the existing zones to become wider in places. The identified zones provide a key starting point for future exploration programs.
The presence of multiple, strike consistent zones is considered highly plausible, as it would explain the significant amounts of uranium that have accumulated on the surface in gypcrete and calcretes at Mile 72. These gypcrete and calcrete deposits recorded some of the highest surface uranium grades of any project globally. Similar significant occurrences of carnotite in sheetwash and weathered bedrock are known in the region, such as at the Aussinanis deposit.
The deeper drilling programs have tested a number of targets in outcropping and covered locations and have tested radon cup anomalism under cover.
Thirty five of the holes have specifically targeted highly anomalous radon cup highs located in a radiometrically barren region in the centre and northwest of the licence. Localised anomalous radon cup anomalism was seen to be potentially representative of buried primary or secondary uranium mineralisation. The drilling found this not to be the case, with the central and northwest areas being underlain by pelitic schist with sporadic pegmatites (barren), which in turn are underlain by deeper granite bodies (also barren). The schist-granite-pegmatite/alaskite geological terrane of the southeast is a stark contrast to the schist-dominated northwest, and is separated by a major geological structure (See Figure 2).
Figure 2:– Several target areas have been defined in a broad zone in the south of the licence (white, cross-hatched). The targets are defined on numerous criteria, including geology, and magnetic and radiometric response. Shown on the licence area are surface geochemical results and high-resolution radiometrics.
The drilling to date, while sterilising a significant portion of the project area, allows future exploration to focus on the most prospective areas and possible trap zones in the southeast terrane. As well as primary Rossing-style uranium mineralisation, the drilling has confirmed the presence of calcrete-hosted uranium potential at Mile 72. The identification of mineralisation in alaskite rocks supports the model favoured by the company that mineralising conditions could exist in the project area.
Figure 3 - Location RC drilling at Mile 72. Drilling has intercepted alaskite-hosted uranium mineralisation in several drillholes in the southeast terrane, defining a series of uranium trends up to 2km long.
The presence of uranium mineralisation at Mile 72 is now known to be locally sourced from numerous strike-extensive alaskite/pegmatite zones in the southeastern part of the licence and allows exploration to focus more tightly on the identification of potentially economic mineralisation in that area. The Company is reviewing the results of all past exploration, focusing in on the southeast terrane. Future programs will be designed to test the area comprehensively to ensure any trap sites are located.