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Since early 2013, ongoing soil sampling has been conducted on variably 1 to 2 km spaced lines and 100m spacing between the lines.
Since then, over 60000 samples have been collected with various phases of infill sampling down to 25m by 25m just prior to drilling. Unlike in Western Australia the soils represent residual insitu primary geology and multi-element geochemical signatures strongly represent their fresh host rocks beneath.
Figure 1: Regional nickel in soil image showing the location of the key nickel prospects found with this technique to date.
The Zn image Figure 2 shows both the Pamwa anomaly plus a large area of strong anomalism in the north east generally known as the Ayuu Alali anomalies.
Figure 2: Regional zinc in soil image showing the location of the key zinc prospects found to date.
The soil data is reviewed and QA/QC checked by Nigel Brand our geochemical consultant. The data is also plotted against known mineral and rock associations Figures 3, 4 and 5 to determine whether the anomalies detected have potential economic significance.
Figure 3: Plot of Ni vs Cr showing association of mineralised mafic/ultramafic rocks from Sipa’s Kitgum Pader project.
Figure 4: Shows the “normal plot” of global rocks where Ni plots against MgO. Akelikongo soils and rocks show enrichment to the normal plot and hence are “fertile”.
Figure 5: Plot of Zn vs Pb where red is the Pamwa mineral system with a strong Zn Pb association and the black is the rest of the data.
The effect of infilling anomalies prior to drilling can be key to discovery where dispersion in the soils is low to non-existent.
Figure 6: Nickel in soils from infill 200 by 50m sampling. Showing location of reconnaissance RAB.
Figure 7: Copper in soils from infill 200 by 50m sampling. Showing location of reconnaissance RAB.
Infill soils resulted in a strong co-incident Ni –Cu anomaly over the mineralisation which the wide spaced RAB drilling missed.
Figure 8: Nickel in soils from infill 200 by 50m sampling. Showing location of reconnaissance RAB.
Figure 9: Copper in soils from infill 200 by 50m sampling. Showing location of reconnaissance RAB.
Drilling over the infill 25 by 25m grid resulted in the Akelikongo West discovery. Figure 10 shows the location of these hole over the 25m by 25m nickel in soils. Figure 11 shows a section of the mineralisation showing the location of anomalous soils.
Figure 10: RAB drill line over nickel in soil anomaly.
Figure 11: Drill section across Akelikongo West showing location of surface expression of soils.
Other anomalies are currently being delineated using these techniques.
Shallow RAB drilling of a single line of holes across the Katanguru soil and rock chip anomaly shows two holes with highly anomalous Nickel geochemistry. Unfortunately due to access issues the line could not be extended far enough east to properly test the peak of the anomaly as shown by Figure 12. Figure 12 shows the infill soil pXRF nickel data with a peak zone of 200m by 100m some immediately north east of the drilled line.
Figure 12: 25m by 25m soils and location of reconnaissance RAB.