Mapping Ni-Cu (PGE) bearing ultramafic rocks with hyperspectral imagery, Nunavik, Canada

Hyperspectral imaging is a promising avenue to facilitate detailed continuous regional mapping in the Arctic, if issues such as low illumination and lichen cover on bedrock can be addressed. This study investigates the use of AISA optical airborne hyperspectral imagery to demonstrate the capability of producing detailed maps to highlight ultramafic rock units associated with Ni-Cu-(PGE) mineralization in the presence of lichen coatings. Spectral and mineralogical analysis of field samples was completed to determine spectral features associated with key index minerals that could be used to discriminate between rock types and lichen. From these spectral features a set of normalized band ratios were developed to map pixels comprising peridotite or pyroxenite rocks associated with mineralization. In addition, an algorithm was developed to effectively minimize calibration issues between flight lines, which impedes the simultaneous analysis of multiple lines.