The Nyanzaga Gold Project (NGP) consists of one Special Mining Lease (SML), nine granted prospecting licences, and one prospecting licence application. Through its subsidiary, Nyanzaga Mining Company Limited (NMCL), Perseus holds an 80% interest in Sotta Mining Corporation (SMCL). The SML was granted on 13 December 2021 to SMCL for an initial period of 15 years. The Treasury Registrar holds the 20% free carried interest of the Government of Tanzania in accordance with the Mining Act.
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Summary:
The Nyanzaga Gold Project (NGP) is situated on the north-eastern flank of the Sukumaland Greenstone Belt. Rock sequences comprise Nyanzian-aged sequences of mafic volcanics in the far south-west and banded-iron-formation, tuffs, mudstone, sandstone and epiclastics of general volcanogenic origin and massive sulphide lenses and volcanics of rhyodacitic to andesitic composition. The sequences are tightly folded and strike generally west-northwest.
In the central part of the NGP, the Nyanzaga and Kilimani groups are defined. The Nyanzaga Group is divided into a sequence of three broad mappable units from drill core and outcrop mapping and are in stratigraphical order as follows:
1. Nyanzaga Upper Volcaniclastic Formation.
2. Nyanzaga Central Formation.
3. Nyanzaga Lower Volcaniclastic Formation.
Nyanzaga
• The Nyanzaga deposit occurs within a sequence of folded Nyanzian sedimentary and volcanic rocks. The current interpretation of the Nyanzaga deposit has recognised a sequence of mudstone, sandstone and chert that are interpreted to form a northerly plunging antiform.
• The mineralisation is hosted by a cyclical sequence of chemical and clastic sediments (chert/sandstone/siltstone) bound by footwall and hanging wall volcanoclastic units.
Kilimani
• At Kilimani, most of the recognised mineralisation occurs in the oxidised profile. Where intersected in fresh material, the mineralisation is associated with strongly carbonate stock work and disseminated replacement. Mineralisation at Kilimani is reported as stratigraphically controlled in thin chert, mudstone and sandstones.
• At Kilimani, the distribution of the gold mineralisation is related to dilation associated with: 1) competency contrast near the sedimentary cycle boundaries resulting in stratabound mineralisation; and 2) sub-vertical faulting, fracturing and brecciation related to the folding and subsequent shearing along the NE limb of the fold.
These three units are folded into the north-northwest plunging Nyanzaga Anticline. These sequences are in turn overlain by the Kilimani Group which appears to be tectonically dislocated from the underlying Nyanzaga Group by faulting and potential earlier thrusts.
A series of different faulting sets has been recognised across the Nyanzaga project area. These include observed outcrop positions with suggested sinistral movement; others with inferred dextral movement; a series of steep faults sub-parallel to bedding; and a number of low angle thrust faults. Additionally, east-west trending normal faults with minor displacement have been identified.
The interaction of these various fault orientations results in the definition of numerous fault block domains. The geological model has focussed on those faults where evidence is observed across multiple sections, and therefore likely to have influence on the geological model at a resource scale. Small scale and discontinuous features are expected to be present but unlikely to materially influence the position of mineralisation within the project.
The two mineralisation systems show similar alteration and mineralisation styles, though the Kilimani deposit is interpreted to have been emplaced at shallower levels than at Nyanzaga. Typical alteration features include pervasive carbonate alteration, varying from distal ferroan-calcite to proximal ankerite-sericite dominated and quartz-pyrite alteration. The current interpretation indicates that there is a distinct lithological control and most of the gold appears to be hosted by iron rich sediments in the form of an extensive stock-work of carbonate, quartz veins, and quartz-carbonate breccias. Preferential grade enhancement occurs in selected altered units such as the thick cherts, silica-dolomite altered medium grained sandstones, brecciated silicacarbonate altered mudstones, or in the late quartz veins as free gold.
As a result of the complex interactions between lithology and faults, definition of discrete mineralisation envelopes is difficult, and attempts to do so are likely to overstate mineralisation continuity, particularly for zones of higher grades.
To mitigate this risk, and to better reflect the anticipated large scale open pit mining method, the mineralisation interpretation instead aimed to define the limits of the mineralisation within the deposit, with the distribution of high-grade mineralisation within this shape reflected in the estimation parameters. A mineralised envelope was defined using an economic compositing routine within Leapfrog using a grade threshold of 0.3 g/t Au and a minimum downhole length of five metres. This length was selected as it was broadly aligned with the expected bench height for the project, while also generating consistent shapes with limited individual internal waste zones which were unlikely to be realistically excluded from the overall domain.
Dimensions
Nyanzaga
• The Mineral Resource extends along a broadly north-south strike interpreted as centred on an anticlinal fold hinge with a moderately dipping western limb and steeply dipping (subvertical) eastern limb. Mineralisation extends approximately 650 m along strike, with mineralisation extending preferentially along the eastern limb up to approximately 750 m down dip. Typical widths vary from 10’s of metres to in excess of 200 m in the centre of the project area.
Kilimani
• The Mineral Resource is interpreted to be variably mineralised along a 900 m strike length. Mineralisation is modelled as stratigraphically controlled along preferential lithologies within the gently folded strata. Typical widths vary from several metres up to 10 metres across several individual strata.