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TitleMulti-camera hyperspectral and MLA-SEM analyses of gossans in the Franklin Large Igneous Province, Victoria Island, Northwest Territories, Canada
AuthorWilton, D H C; Williamson, M-CORCID logo; Lypaczewski, P; Bethell, E M; Brassard, E; Lemelin, M
SourceGeological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 45, 2022 p. 224
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20210708
PublisherThe Geological Association of Canada
MeetingGAC-MAC-IAH-CNC-CSPG Joint Meeting; Halifax; CA; May 15-18, 2022
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS67C; 67F; 67G; 77; 78A; 78B; 78C; 78D; 87; 88A; 88B; 88C; 88D
AreaVictoria Island
Lat/Long WENS-120.0000 -100.0000 74.0000 68.0000
Subjectsmineralogy; spectral analyses; gossans; soil samples; climate, arctic; arctic geology
ProgramGEM-GeoNorth: Geo-mapping for Energy and Minerals GEM Program Coordination
Released2022 05 01
AbstractGossans are extensively oxidized and altered products derived from Fe-rich protoliths at the Earth's surface. They are composed of quartz, Fe-oxides, Fe-hydroxides and, in some cases sulphates such as gypsum and/or jarosite. Most gossans are small (a few metres to less than 1 to 2 km in length), and they are routinely noted by a single point on geological maps. In the barren Arctic tundra, gossans are highly visible on the landscape because of the yellow-orange colouration of the oxide cap. Gossans are commonly, but not solely, formed from the alteration of sulphide minerals in mafic and ultramafic rocks. Consequently, the observation of these types of gossans is an important indicator of local economic mineralization (e.g. Voisey's Bay, Labrador). In the Canadian Arctic Islands, some gossanous terrains at surface are derived from sulphide mineral occurrences and others are derived from reactive processes in permafrost, for instance active gypsum diapirs. The geological quandary lies in how to distinguish one type from the other, and ultimately, in understanding the processes that lead to the formation of barren vs. fertile gossans. We analyzed gossanous soil sampled at two localities on Victoria Island, NT, using (1) MLA-SEM analysis, and (2) the College of the North Atlantic's multi-camera hyperspectral scanning unit (HSU). The MLA-SEM provided quantitative mineral data which readily identified the protolith of the particular gossan. The HSU also distinguished gypsum-bearing gossan material from the others, and in some of these other samples, an Al-OH absorption typical of white micas was detected. The hyperspectral results suggest that an HSU-mounted drone system could readily distinguish between gossans derived from sulphide mineral occurrences, and others derived from reactive processes in permafrost.
Summary(Plain Language Summary, not published)
Gossans are highly weathered, iron-rich soils overlying bedrock. The mineralogy of gossans results from the oxidation of sulphides by acidic and oxidizing fluids. These deposits form in a wide range of geologic settings but outcrops are generally a few meters to kilometers in size. We analysed samples from gossans located on Victoria Island, Northwest Territories, using 1) MLA-SEM analysis, and 2) the College of the North Atlantic's multi-camera hyperspectral scanning unit (HSU). This presentation is an overview of the most relevant findings, and of potential applications in the search for critical mineral deposits in northern Canada.

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