Application of Airborne, Laboratory, and Field Hyperspectral Methods to Mineral Exploration in the Canadian Arctic: Recognition and Characterization of Volcanogenic Massive Sulfide-Associated Hydrothermal Alteration in the Izok Lake Deposit Area, Nunavut, Canada

Abstract

We have investigated the application of ground, laboratory, and airborne optical remote sensing methods
\nfor the detection of hydrothermal alteration zones associated with the Izok Lake volcanogenic massive sulfide
\n(VMS) deposit in Nunavut, Canada. This bimodal-felsic Zn-Cu-Pb-Ag deposit is located above the tree line in
\na subarctic environment where lichens are the dominant cryptogamic species coating the rocks. The immediate
\nhost rhyolitic rocks have been hydrothermally altered and contain biotite, chlorite, and white micas as
\ndominant alteration minerals. These minerals have spectral Al-OH and Fe-OH absorption features in the shortwave
\ninfrared wavelength region that display wavelength shifts, which are documented to be due to chemical
\ncompositional changes. Our ground spectrometer measurements indicate that there is a systematic trend in
\nthe Fe-OH absorption feature wavelength position of biotite/chlorite with increasing distance from the VMS
\ndeposit: the average Fe-OH absorption feature wavelength position of the proximal areas (398–3,146 m from
\nmineralization) is observed at 2,254 nm, and that of the distal areas (5,782–6,812 m) at 2,251 nm. Moreover,
\nthe proximal areas have an average Al-OH absorption feature wavelength position at 2,203 nm, in contrast with
\nthe average wavelength position at 2,201 nm in the distal areas, implying a spectral shift of 2 nm. These findings
\nindicate that hydrothermal alteration zones can be detected by hyperspectral remote sensing, despite the presence
\nof abundant lichen cover. However, the airborne results discussed in this study required the screening out
\nof more than 99% of the pixels in the area.