Keep up to date with all the latest news and announcements by subscribing to our free email alerts service.
Akelikongo is Sipa's flagship discovery in Uganda. During 2015 and 2016, geochemistry, drilling and geophysics defined a sizeable body of nickel-copper sulphide mineralisation which has strong similarities to other globally significant, intrusive-related magmatic nickel copper sulphide systems such as Nova-Bollinger (14Mt @ 2.3% Ni and 0.9% Cu), Voisey's Bay (141Mt @ 1.6% Ni and 0.8% Cu) and Raglan (30Mt @ 3.4% Ni and 0.9% Cu).
The key elements of these systems are a plunging magma channel or conduit with a high magma fluid flux which then interacts with the country rock during emplacement to form a mixing zone, which triggers sulphur saturation and the formation of nickel-copper sulphide mineralisation.
At Akelikongo, the conduit essentially sub-crops with an intense nickel and copper anomaly in residual soil. The infill soil samples have now confirmed the circular pipe like geometry of the shallowly plunging intrusive complex. This anomaly has a surface footprint of about 300m by 300m which has been traced by drilling for up to 1km and remains open in all directions (Figure 1).
Figure 1: Akelikongo Schematic Long Section.
Drilling shows it then continues down plunge for at least 500m and is interpreted to extend more than a kilometre where holes to the north (AKD003 and 12) have detected alteration due to a probable nickel system in form of anomalous nickel copper and platinum group element (PGE) geochemistry in the felsic paragneisses.
The discovery at Akelikongo West of a second mineralised intrusive body with a different geological and geochemical character, demonstrates the Akelikongo field contains multiple mineralised intrusive systems indicative of a mineral field with a complex history enhancing its economic potential.
Data integration indicates the magmatic disseminated sulphides at Akelikongo show a linear nickel tenor trend up to 12% with massive sulphides averaging 4-6%. These nickel tenors are encouraging and an early stage indicator that any larger accumulations of sulphide mineralisation are likely to be economic.
Results of the recent drilling during 2016 have shown that the previously sparsely drilled western footwall to the system has a prospective basal position and has formed an embayment where sulphides have accumulated within a much larger up to 110m wide disseminated zone.
Drilling in late 2016 resulted in the widest disseminated and thickest semi-massive sulphide zones intersected to date with results such as:Matrix to semi-massive zones:
Continuous disseminated and semi-massive intercepts:
Since Rio commenced funding the Joint Venture, a total of five holes for 1,993.5m have been drilled at Akelikongo. The results indicate further nickel and copper sulphide mineralisation at Akelikongo Main and also at the emerging “Eastern zone” towards the base of the intrusive complex (see Figure 2). The emerging eastern zone is located around 200m to the east of the main outcropping mineralisation drilled by Sipa during 2015-2017.
Figure 2: Plan of current drilling at Akelokongo, (purple dotted outline marks outline of intrusion) showing results from AKD018-22 and new eastern mineralised zone (schematic), shown in yellow.
At the emerging eastern zone, disseminated and minor massive sulphides have now been intersected in holes including drilled holes AKD020, AKD021 and AKD022.
The zone is interpreted to have been previously intersected in holes AKD014 and AKD016, drilled previously by Sipa in 2015. AKD019 has intersected near-surface mineralisation which extends from the previously drilled main zone further to the east.
AKD020 intersected a 16.4m wide mineralised zone with blebby and disseminated sulphides ranging from 10% to 30% rock volume with assay results of 1.3m at 1.52% Ni 0.2% Cu and 0.1% Co within a broader intercept of 16.4m @ 0.44% Ni, 0.12% Cu and 0.03% Co from 274.3m to 290.7m.
This hole successfully tested a modelled DHEM plate detected off-hole from diamond hole AKD015 and forms part of the eastern mineralised zone.
AKD021 intersected disseminated, vein and semi-massive sulphide mineralisation also located towards the base of the Akelikongo ultramafic intrusion about 100m along strike from AKD020. The mineralised zone assayed 0.41% Ni and 0.12% Cu over 10.20m from 298.70m (calculated using 0.25% Ni cut-off).
An internal zone of semi-massive sulphide within this interval assayed 1.2% Ni and 0.15% Cu over 0.40m. This zone also successfully tested a previously identified off hole DHEM plate target.
The success of AKD020 and AKD021 in intersecting strong sulphide mineralisation at the modelled DHEM positions confirms the effectiveness of DHEM as a key targeting tool for further drilling as the mineral system continues down-plunge.
AKD022 stepped out a further 200m down-plunge and intersected two zones of disseminated, vein and semi-massive sulphide mineralisation located towards the base of the intrusion.
The upper zone assayed 0.29% Ni and 0.07% Cu over 11.7m from 290.80m. The lower zone assayed 0.30% Ni and 0.08% Cu over 18.40m from 304.60m.
AKD019 intersected near-surface mineralisation containing moderately disseminated magmatic sulphides associated with harzburgite, peridotite and norite from 29m to 49m, with an intersection including an oxidized zone from 29-39m of 10m @ 0.49% Ni and 0.16% Cu and 10m of sulphide mineralisation from 39m @ 0.43% Ni and 0.13% Cu.
This zone is interpreted to be an eastern extension of the upper outcropping “main” mineralisation previously drilled by Sipa.
AKD018 drilled down the margin of the Akelikongo Ultramafic complex and intersected a small zone of massive sulphide which has been intruded into the gneiss at 397m.
Assay results >0.25% Ni are summarised below. Results where aggregated have generally less than 1m internal dilution and are reported using a length weighted average technique.
Down-hole EM is being undertaken on these holes before further targeting commences.
Commenting on the results, Sipa Resources’ Managing Director, Lynda Burnett, said: "The diamond drilling assays have provided encouragement for ongoing exploration at Kitgum_Pader, confirming extensions of the main zone of outcropping nickel-copper mineralization at Akelikongo while also further delineating the new 'Eastern Zone' of mineralization reported in our last announcement."
"Given that this zone remains open down-plunge beyond the current drilling, it provides a clear vector for follow-up exploration. Regional geochemical characterisation work has also confirmed that we are in a fertile environment for magmatic nickel-copper sulphide discoveries, highlighting the prospectivity of the regional intrusions."
"Putting all the information together, we believe the Joint Venture has made a very strong and encouraging start to the exploration program at Kitgum Pader. Everything we have seen confirms that this is a highly prospective, district-scale opportunity for nickel sulphide discovery."