Lot A1

Au (Vein Type) & PGM, Ni_Cr_Co

Anomalous results for chromite, PGE-Ni-Cr-Co nickel and copper/IOCG type mineralization with anomalous Cu/Pb/Au.

Study Areas: Tsauni (Niger State) / Sado, Sado South, North Wuya, Kumbo (Zamfara State) / Bin Yauri South, Bin Yauri East, Bin Yauri North (Kebbi State) / Ilesha (Osun Sate)

The late tectonic stages of a regional dextral shortening established the principal structural architecture in the basement cover complex and the progressive strain localisation along a series of crustal scale shear zones. The emplacement of ultramafic intrusive complexes associated with Ni-Cr-Co-PGE mineralisation occurred along these major shear zones. A late high-level sinistral re-activation was associated with extensive gold mineralisation through Nigeria, hosted within the basement gneiss complex and in particular, within the entrained supracrustal sequences.

The NIMEP Exploration Projects Under the Lot A1 Work Program

Nigeria is within the Trans-Saharan Mobile Belt, a Pan-African orogenic belt which comprises reworked Archaean and possibly Paleoproterozoic crust and bounded to the west by the >2 Ga West African Craton and to the east and south east by the East Saharan Craton and the Congo Craton respectively.

The Nigerian Shield is a granite–gneiss dominated terrane characterised by two domains; the Western and Eastern Nigerian shields. These are discriminated by distinct litho-structural and metallogenic associations. The Western Domain comprises a volcano-sedimentary cover sequence collectively referred to as the Schist Belts. These represent relatively low grade supracrustal sequences (which include clastic and chemical sediments and volcanic units) entrained within the migmatitic gneissic basement sequence.

The Schist Belts are spatially associated with crustal-scale, late-tectonic, NNE – SSW trending shear zones which transect the country. These structures represent the last significant deformation to have occurred in the Pan-African event and deform the youngest (600–580 Ma) Older Granite suites.

Late tectonic strain localisation along these regional crustal scale shear zones is characterised by an apparent dextral displacement and were the primary structural controls for much of the gold vein mineralisation, the emplacement of Ni-Cr-Co-PGE intrusive complexes and late stage emplacement of mineralised pegmatites.

The NIMEP project is a Nigerian Government initiative to demonstrate the exploration feasibility for economic mineral deposits in Nigeria with the aim of providing a basis for international investment in the exploration and mining sector.

To this end the NIMEP project aims to discover and characterise mineral resources for a number of specified commodities, providing detailed geological constraints and associations that build towards a more comprehensive understanding the mineral systems in Nigeria.

Here is detailed the work program for the Lot A1 project which includes the target commodities of vein related Au and associated base metals and magmatic Ni-Cr-Co-PGE mineralisation. The initial project area encompasses an exploration extent in excess of 300,000km covering much of western Nigeria.

The initial program works programs were to identify more focused targets zones within this extensive area which involved the construction of a regional litho-structural geometry through the interpretation of airborne magnetic and radiometric datasets. This provided a basis to build an understanding of the tectonic development in the Pan-African of Nigeria and form the foundation for the development of tectonic framework for understanding the control and distribution of the target mineralisation systems. This work lead to the identification of target areas for on-ground exploration activities.

A total of 9 project areas were identified for follow up, on-ground exploration programs which included two Ni-Cr-Co-PGE targets and seven Au-base metal targets. Subsequent work has identified an additional Ni-Cr-Co-PGE targets associated with one of the gold projects.

The on-ground field programs include:

  • Geological mapping and the acquisition of ground magnetic data. Detailed Litho-structural interpretations have been completed over these project areas and formed the basis for the targeting and implementation of geochemical sampling programs.
  • Extensive soil sampling programs involving an initial first phase wide spaced sampling program was then infilled with more detailed sampling across defined anomalous zones. A series of prospect scale targets zones have been identified through all project areas. A select series of targets were chosen for follow up in trenching and drilling programs, the last phase of the project.

The late tectonic Pan-African structural geometry and the location of the Nine project areas for both the Au and Ni-Cr-Co-PGE projects.

Gold hosted vein work programs

The litho-structural gold targets which have been the focus of the Lot A1 project. All of the target mineralisation associations are related to a late tectonic sinistral reactivation.

The Tsauni project area occurs along the eastern margin of the Eastern Structural Domain. The targets include a series of discrete vein systems developed within a broad (~6km) discordant demagnetised zone. Regional first phase (500 x 50m sample grid) and infill (125x25m) soil results highlight a domaining of metals within this structural zone with anomalous Au, Pb and Zn defining a series of structural corridors in the west while a discrete zone along the contact with a mafic gneiss in the east is characterised by ultramafic intrusive dyke sets with anomalous Ni, Cr and Cu.

Ni-Cr-Co-PGE intrusive work programs

The emplacement of the two targeted intrusive ultramafic-mafic complexes were controlled with the Anka shear zone. These complexes were emplaced relatively late and prior to the main gold mineralisation event.

The Talata prospect is a small layered ultramafic complex with an outcrop extent of 2.6 km x 1 km. This ultramafic complex represents a small aphothyses above a larger concealed intrusive complex emplaced within a supracrustal sequence entrained along the Anka Shear Zone.A completed soil geochemistry program reveals strongly anomalous Ni and Cr with associated anomalous Cu, Co and Pd.

The Kumbo targets are a series of intrusive mafic to ultramafic plutons and dykes emplaced into a supracrustal sequence and within the pressure shadow zone of an earlier granite complex.Flattening strain associated with the dextral transpressional deformation along the Anka Shear Zone lead to the attenuation and boudinage of a relict meta-volcanosedimentary sequence between older rigid, granite intrusive bodies.

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