The Project area is characterised by the presence of norites and gabbro-norites containing disseminated Ni-Cu sulphides. The mafic rocks bearing Ni-Cu mineralisation were found in the boulders and also in one small outcrop located approximately 500m from the bitumen road passing through the licenses (Fig. 2).
Figure 1. Nottrask Project license area and photograph of outcrop of Ni-Cu Sulphides identified in historic exploration in the southern ‘eye’.
The intrusion hosts Ni-Cu sulphide mineralisation which was initially explored in the early 1980’s and in 2000. Past exploration was predominantly focused on the small area around the outcrop of the massive sulphides in the southern ‘eye’, with the remainder of the license practically untested by modern geophysical methods or by drilling.
During its recently completed due diligence program, Boss identified a new occurrence of Ni/Cu sulphides in the northern ‘eye’, approximately 5km from the first outcrop where previous mapping and sampling done by Boss identified Ni grades up to 1.25% and Cu grades up to 1.8%. The due diligence program comprised acquisition of data from the Swedish Geological Survey (SGU), compilation of an exploration database, mapping and geochemical prospecting of the area with an emphasis on the northern ‘eye’ of the intrusive system.
The new sulphide outcrop indicates that the mineralised system at Nottrask is significantly larger than thought in the past, when exploration efforts were focused on a small area around the historic outcrop. Both sulphide outcrops were found in the norite and gabbro-norite unit close to its contact with overlaying ferro-gabbro unit.
Boss has targeted key areas for future exploration that include the entry points (feeder dikes) to the intrusion as illustrated on the airborne magnetics. Future programs of work include review of existing geophysical data and development of a quantitative model, undertaking a high resolution airborne magnetic survey, and completing high powered modern TEM to search for conductors along the interpreted contact.
Boss is also encouraged by the composition of olivine (rock forming mineral) in the Nottrask rocks which is in the range of 55-75 mol% Fo. Recent petrologic and geochemical studies of the ultramafic complexes have shown that economically viable sulphides with Ni tenor 2.75% are formed in the intrusions containing moderately magnesian olivine containing 60mol% Fo. Based on this, the composition of olivine at Nottrask, which often exceeds 60 mol% Fo (up to 75 mol% Fo), is favourable for generating economically viable sulphide mineralisation with Ni tenor greater than 3%.