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TitleMineralogy and spectral signature of reactive gossans, Victoria Island, NT, Canada
AuthorPercival, J B; Williamson, M -C
SourceApplied Clay Science vol. 119, 2015 p. 431-440, https://doi.org/10.1016/j.clay.2015.05.026
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20150091
PublisherElsevier
Documentserial
Lang.English
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories; Nunavut
NTS87H/04; 87H/06
AreaVictoria Island; Minto Inlier; Gossan Hill
Lat/Long WENS-116.0000 -115.6667 71.2750 71.2000
Lat/Long WENS-114.5833 -114.5833 71.4000 71.3333
Subjectsmineralogy; surficial geology/geomorphology; gossans; analytical methods; x-ray diffraction; spectrometric analyses; glacial deposits; permafrost; freezing ground; ground ice; mine waste products; x-ray diffraction; mass wasting; erosion; Quaternary
Illustrationslocation maps; photographs; tables; spectra
ProgramTools for environmental impacts and adaptation for metal mining, Environmental Geoscience
AbstractGossans resulting from the oxidation of sulphide-rich bedrock occur sporadically across Canada, and these features are routinely indicated on geological maps published by the Geological Survey of Canada (GSC). In the Canadian Arctic Islands, some gossans display reactive zones in permafrost characterized by specific textures and mineralogical facies. In poorly-vegetated areas of the High Arctic, gossans can easily be detected on highresolution satellite imagery. However, the mechanisms leading to their formation are poorly known. For this study, two reactive gossans located in the early Neoproterozoic Minto Inlier of Victoria Island, Northwest Territories, were investigated to determine if the deposits constitute (1) analogues of mine waste in permafrost and (2) vectors to economic resources. Mineralogy was determined in situ using a portable spectroradiometer, with follow-up laboratory measurements. Site 1, Gossan Hill, is a 75-m topographic high capped by a poorly consolidated, rust-coloured layer overlying pyrite-rich sands, and resembles a classic gossan. Site 2, Gossan Sill, underlies a mineralized gabbroic sill consisting of sulphide-rich veins and pods but appears to be inverted morphologically. Visible-Near Infrared-Short Wave Infrared spectral analyses of surficial materials at Gossan Hill indicate gypsum, goethite and jarosite, and X-ray diffraction (XRD) confirms their presence as well as quartz, illite and feldspar. At Sill Gossan, spectral analyses show gypsum and jarosite; XRD indicates variable amounts of goethite, hematite, pyrite, chlorite, calcite and feldspar. The positive relief and presence of concentric alteration zones at Gossan Hill suggest that cryogenic processes, typical of Arctic regions, are active. Water becomes expelled during the freezing cycle forcing material outwards and along with oxidation of the sulphides, forms variably coloured zones in gossanous material. The inverted stratigraphy at Sill Gossan is more problematic. Constant weathering and mass wasting from the overlying sill and pyrite-rich breccia provide fresh pyrite to the gossan on a regular (seasonal) basis.
Summary(Plain Language Summary, not published)
This paper presents the results of a mineralogical study of two gossans discovered on Victoria Island, NT. Gossans that react with permafrost constitute analogues of mine wastes that could be generated from a mine in this sensitive environment. In addition, gossans are studied as potential vectors for mineral deposits. The paper presents the results of detailed mineralogical analyses of surficial deposits collected from these gossans that were obtained using infrared spectroscopy measurements combined with X-ray diffraction analysis.
GEOSCAN ID296603