Use of airborne hyperspectral and gamma-ray spectroscopy data for mineral exploration at the Sarfartoq carbonatite complex, southern West Greenland

Abstract

The Sarfartoq carbonatite complex occurs in the transition zone between Archaean and Paleoproterozoic gneisses in southern West Greenland. The Sarfartoq carbonatite complex hosts ore deposits and occurrences of rare earth elements and niobium. In this study, airborne HyMap hyperspectral imagery and coincident airborne gamma-ray spectroscopy data were analysed for mineral exploration of Sarfartoq carbonatite complex. The study area included the carbonatite core zone and a hydrothermally altered shear zone prospective for rare earth elements mineralization in the southern margin of the carbonatite complex. The analysis of the hyperspectral imagery was focused on the mapping of the spatial distribution of carbonatite, fenite and limonite. Significant anomalies of uranium, thorium and potassium were outlined from the gamma-ray spectroscopy data. Decision trees were used to combine the results from the hyperspectral image analysis and airborne gamma-ray spectroscopy. Significant anomalies of thorium at the hydrothermally altered shear zone coinciding with the presence of carbonatite rocks are generally indicative of outcropping rare earth element mineralization. The study indicates the benefits of coincident airborne hyperspectral and gamma-ray spectroscopy surveys for the mineral exploration of carbonatite complexes.