Overview of surficial geochemistry and indicator mineral surveys and case studies from the Geological Survey of Canada's GEM Program

M. Beth McClenaghan, Wendy A. Spirito, Stephen J. A. Day, Martin W. McCurdy, Rick J. McNeil and Stephen W. Adcock
Geochemistry: Exploration, Environment, Analysis, 22, geochem2021-070, 3 February 2022, https://doi.org/10.1144/geochem2021-070

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Figures

  • Fig. 1.
    Fig. 1.

    Locations of GEM-supported reconnaissance- and regional-scale geochemical surveys conducted as part of the GEM program across northern Canada indicated by coloured polygons: lake sediment (blue), stream sediment (yellow), till (green), combined stream sediment and till (purple). The large area covered by the joint GSC-Quebec-Newfoundland and Labrador organic lake sediment geochemical data compilation is outlined by a dashed line (area #1). Other surveys mentioned in the text are numbered from #2 to #12. GEM deposit-scale study locations are indicated by yellow dots.

  • Fig. 2.
    Fig. 2.

    Distribution of trace elements in the <0.177 mm fraction of lake sediments samples from Quebec and Labrador determined by aqua regia/ICP-MS: (a) Sb (ppm), (b) As (ppm), (c) Bi (ppm), and (d) Re (ppb). Modified from Amor et al. (2019).

  • Fig. 3.
    Fig. 3.

    Proportional dot map of weighted sum scores for the Mississippi Valley-type Zn-Pb deposit model used to evaluate new lake sediment geochemical data for west central Baffin Island, Nunavut. From Bonham-Carter et al. (2019).

  • Fig. 4.
    Fig. 4.

    Gold content in surficial sediments for southern Melville Peninsula: (a) proportional dots (open circles) showing gold grain abundance in the heavy mineral fraction of bulk till samples (normalized to 10 kg); (b) proportional dots (solid brown) showing Au (ppb) concentration in the <0.063 mm fraction of till determined by aqua regia/ICP-MS; and (c) grey contours showing Au (ppb) concentration in the <0.177 mm fraction of lake sediments determined by aqua regia/ICP-MS. Dashed blue lines indicate position of ice divide, blue arrows indicate ice-flow directions. GR/GN: Precambrian granite and gneiss; PAG: Prince Albert Group Archean supracrustal rocks; PEN: Penrhyn Group Paleoproterozoic supracrustal rocks- marble-rich units; CARB: Paleozoic carbonate rocks. Modified from Tremblay et al. (2016).

  • Fig. 5.
    Fig. 5.

    Interpolated map of Cu (ppm) concentrations in the <0.177 mm fraction of lake sediments in the southern Northwest Territories and Nunavut and in northern Saskatchewan; inset map shows Cu data for lake sediment samples in the Abitau Lake area (NTS 75B). Data from McCurdy et al. (2012, 2015, 2016a).

  • Fig. 6.
    Fig. 6.

    Proportional dot maps of abundance of (a) sphalerite and (b) galena grains in the 0.25–0.5 mm heavy mineral fraction (normalized to a 50 g heavy mineral fraction weight) of stream sediment samples in SW NWT. The large black rectangle is the Pine Point mining district. From Paulen et al. (2018).

  • Fig. 7.
    Fig. 7.

    Proportional dot map of Ni concentrations in the <0.177 mm fraction of lake sediments determined by aqua regia/ICP-MS in the Gods Lake area, Manitoba. Value at each sample site represents the rank with respect to all values within a radius of 40 km. The location of known mineral occurrences that contain Ni as a commodity are indicated with red stars. From McCurdy et al. (2017).

  • Fig. 8.
    Fig. 8.

    Colour photograph of blue-green sand-sized gahnite grains used as an indicator mineral to map dispersal from the high grade metamorphosed Izok Lake VMS deposit, Nunavut. Photograph by Michael J. Bainbridge Photography.

  • Fig. 9.
    Fig. 9.

    Proportional dot map of gahnite abundance in surface till normalized to a 10 kg sample mass around the Izok Lake VMS deposit showing the proximal part of the 40 km long dispersal fan formed by older SW (blue polygon) and then modified by younger NW (yellow polygon) ice flow across the Izok Lake VMS deposit. Arrows indicate relative ice-flow chronology (1  =  oldest) and vigour (arrow size) of flow events. Modified from Paulen et al. (2013) and McClenaghan et al. (2015). Locations of gahnite-bearing rocks at surface indicated by green stars and location of massive sulfide indicated by solid red polygons (unpublished data, MMG Ltd.).

  • Fig. 10.
    Fig. 10.

    Proportional dot map of gahnite abundance in reconnaissance-scale till samples collected in 1994 as part of a previous survey normalized to a 10 kg sample mass showing a 40 km long dispersal fan (yellow polygon) formed by NW ice flow across the Izok Lake VMS deposit. Arrows indicate regional relative ice flow chronology (1  =  oldest) and vigour (arrow size) of flow events. Modified from McClenaghan et al. (2015).

  • Fig. 11.
    Fig. 11.

    Till composition and ice flow trends in the area of former producing pit O-28 in the east part of the Pine Point Pb–Zn mining district, NWT. Distribution of sphalerite grains in the 0.25–0.5 mm non-ferromagnetic heavy mineral fraction of till in the area: (a) west and SW of deposit; and, (b) immediately west of the open pit. Distribution of Zn (ppm) in the <0.063 mm fraction of till in the area: (c) west and SW of deposit; and (d) immediately west of the open pit. At sites where more than one till sample was collected at different depths, the data are plotted as vertically stacked symbols. Green polygons outline metal-rich till dispersed by the older SW ice flow. Yellow polygons outline metal-rich till dispersed to the NW from the mineralization (blue) and/or re-entrained from the older SW dispersal train. White dots indicate barren till samples. From McClenaghan et al. (2018).

  • Fig. 12.
    Fig. 12.

    Colour photographs of indicator mineral grains recovered from till in the Pine Point Mining District: (a) honey brown sphalerite; (b) dark brown Fe-rich sphalerite; (c) galena. Mineral photography by Michael J. Bainbridge Photography.

  • Fig. 13.
    Fig. 13.

    Colour photographs of selected indicator minerals from bedrock and from till samples overlying and down ice of the Strange Lake rare earth element deposit: (a) orange monazite; (b) orange-brown octahedral pyrochlore; (c) white bastnaesite grains; (d) reddish brown to black fibrous arfvedsonite; (e) black allanite; (f) black glassy chevkinite; (g) dark purple fluorite; (h) dark brown-black allanite intergrown with white gittinsite. Mineral photography by Michael J. Bainbridge Photography. Modified from McClenaghan et al. (2017c).

  • Fig. 14.
    Fig. 14.

    (a) Line plot of total Th in ppm (INAA) concentration in the <0.063 mm fraction of surface till, down ice of the Strange Lake rare earth element deposit in eastern Canada, with the best-fit data curve shown as a dashed line. Data are from Batterson and Taylor (2009). (b) Idealized glacial dispersal train, modified from Klassen (1997), that shows the linear relationship between the source, head and tail of a dispersal train formed by a palaeo-ice stream. From Paulen et al. (2017).

  • Fig. 15.
    Fig. 15.

    Dot map of Cu (ppm) concentrations in the <0.002 mm clay-sized fraction of surface till determined by aqua regia/ICP-MS around the Sue-Dianne Cu–Ag–U–Au IOCG deposit in the Great Bear magmatic zone, NWT. From Normandeau (2018).

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Geochemistry: Exploration, Environment, Analysis: 22 (1)
Geochemistry: Exploration, Environment, Analysis
Volume 22, Issue 1
February 2022
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