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Generalized geological map of the Mackenzie Mountains draped on a digital elevation model. Geology is simplified from Wheeler et al. (1996) with modifications following Martel et al. (2011) and D. Irwin and A. Okulitch (unpublished data). The approximate transition between the Lower Paleozoic Mackenzie Platform (MP) and Selwyn Basin (SB) is shown by a solid white line, modified after Gordey and Anderson (1993) and Martel et al. (2011). This transition shifted in position over time during the Paleozoic, so this is simply a generalized reference. Mineral occurrences are derived from the NORMIN.db (available at www.ntgomap.nwtgeoscience.ca). ARR-Arctic Red River; GR-Gayna River; KR-Keele River; LR-Liard River; MRMackenzie River; MtR-Mountain River; NNR-North Nahanni River; NWT-Northwest Territories; RR-Redstone River; RTR-Ravensthroat River; SNR-South Nahanni River; YT-Yukon Territory.
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The Mackenzie and eastern Selwyn Mountains, Northwest Territories, Canada, are the northeast expression of the Cordilleran orogen and have a geologic history that spans the last one billion years. The region has undergone a diverse tectonic evolution, which is reflected in an equally diverse collection of mineral deposits and prospects. More than 3...
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... sub-Windermere and Cambri- an extension (Cecile et al. 1997;Hadlari et al. 2012). This led to sedimenta- tion on a number of segmented plat- forms, arches, and basins, resulting in numerous formations with complex lateral thickness variations and facies relationships. For simplicity, this is referred to collectively as the Macken- zie Platform ( Fig. 2; Morrow 1991;Gordey and Anderson 1993;Cecile et al. 1997;Martel et al. 2011). The oldest Cambrian strata in the Mackenzie Plat- form consist of shallow-marine to flu- vial quartz sandstone (Backbone Ranges Formation). This is overlain by shallow-water Cambrian to Devonian dolostone and limestone assigned to various formations (e.g., ...
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... are defined after Jefferson (1983) and Jefferson and Parrish (1989). Geographical abbreviations are in Figure 2. ...
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... of the carbonate-hosted Zn-Pb occurrences in the MSM area, and therefore it is not currently possible to evaluate this concept. Carbonate-hosted Zn-Pb (± Cu, Ag, Ba, Sb, Ga) Over 230 Zn-Pb (± Cu, Ag, Ba, Sb, Ga) prospects and deposits are present throughout the MSM area in the Paleo- zoic Mackenzie Platform that formed east of the Selwyn Basin ( Fig. 12 Nelson et al. 2002;Goodfellow 2007;Leach et al. 2005;Paradis et al. 2007;Lund 2008). As Paradis (2007) and Wallace (2009) point out, however, many other aspects of these mineralized zones are consis- tent with the MVT classification ( Leach et al. 2005;Paradis et al. ...
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... key carbonate-hosted, base-metal deposits in the MSM area are Gayna River, Bear-Twit, Prairie Creek, and potentially Wrigley-Lou (Figs. 5D-E and 12; Heal 1976). Gayna River is in the northern Mackenzie Mountains (Fig. 12), and is character- ized by breccia-cemented, gallium-rich sphalerite (Fig. 5D) with lesser pyrite and hematite, hosted in the Neopro- terozoic Little Dal Group (Hewton 1982;Dewing et al. 2006;Wallace 2009). An historical resource estimate of 50 million tonnes with over 5% combined Zn-Pb is reported by Hewton (1982 ; Table 1), although ...
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... hematite, hosted in the Neopro- terozoic Little Dal Group (Hewton 1982;Dewing et al. 2006;Wallace 2009). An historical resource estimate of 50 million tonnes with over 5% combined Zn-Pb is reported by Hewton (1982 ; Table 1), although the over- all tonnage is probably exaggerated (Wallace 2009). The Bear-Twit prospect, southeast of Gayna River (Fig. 12), contains Zn-Pb-Cu-Ag (sphalerite, galena, tetrahedrite) in veins that cross-cut Paleozoic strata ( Dewing et al. 2006). Bear-Twit has an historical resource estimate of 7 million tonnes @ 5.4% Zn, 2.6% Pb, and 17.1 g/t Ag, although the overall tonnage may be over-estimated ( Dewing et al. 2006). Prairie Creek, in the southern Macken- ...
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... Zn-Pb-Cu-Ag (sphalerite, galena, tetrahedrite) in veins that cross-cut Paleozoic strata ( Dewing et al. 2006). Bear-Twit has an historical resource estimate of 7 million tonnes @ 5.4% Zn, 2.6% Pb, and 17.1 g/t Ag, although the overall tonnage may be over-estimated ( Dewing et al. 2006). Prairie Creek, in the southern Macken- zie Mountains (Fig. 12), contains stratabound, sphalerite-galena-bearing ore (Fig. 5E) hosted in the Ordovician Whittaker Formation as well as late, Ag-rich, Pb-Zn veins that crosscut early Paleozoic carbonate rocks and shale (Paradis 2007). Canadian Zinc Corporation is in the process of devel- oping a mine plan for the Prairie Creek Zn-Pb-Ag deposit, and ...
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... data from includes only galena data from prospects in the Mackenzie Mountains. Figure 12. Geographic distribution of Paleozoic strata and Mackenzie Platform-hosted Zn-Pb (+ base-metal) occurrences. ...
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... distribution of Paleozoic strata and Mackenzie Platform-hosted Zn-Pb (+ base-metal) occurrences. Note that some prospects near the platform-basin boundary may be related to the SEDEX occurrences in Figure 8. MP - Mackenzie Platform; SB -Selwyn Basin; all other geographical abbreviations are as in Figure 2. ...
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... on Figure 11 (Heal 1976), but fall within the Cordilleran carbonate-lead trend. Notably, the signature from the Pine Point MVT deposit is significantly less radiogenic than that of lead from the carbonate-hosted Zn-Pb prospects in the MSM area, likely indicating distinct and separate mineralizing events, fluid pathways, and/or fluid sources ( Fig. 11; Hannigan ...
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... and Pb isotopic data suggest that a minimum of two generations, but more likely three or four, of carbonate-hosted Zn-Pb (+ other base-metal) deposits are present in the MSM area. These include: (1) stratabound ore at Prairie Creek that is similar to, and possibly related to, the Cambrian-Mississippian SEDEX type in the Selwyn Basin to the west (Figs. 10 and 12); (2) vein and breccia-hosted Zn-Pb deposits, such as those at Gayna River and Bear-Twit, which may or may not be related to SEDEX mineralization (Figs. 10 and 12); (3) possible MVT deposits, and; (4) ca. 250 to 60 Ma, vein-hosted, Ag- Zn-Pb deposits, such as those at Prairie Creek (Figs. 10 and ...
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... SEDEX type in the Selwyn Basin to the west (Figs. 10 and 12); (2) vein and breccia-hosted Zn-Pb deposits, such as those at Gayna River and Bear-Twit, which may or may not be related to SEDEX mineralization (Figs. 10 and 12); (3) possible MVT deposits, and; (4) ca. 250 to 60 Ma, vein-hosted, Ag- Zn-Pb deposits, such as those at Prairie Creek (Figs. 10 and ...
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... to reflect their magmat- ic sources. Magmatic segregation and differentiation processes may have also played a role in the formation of tung- sten skarns ( Rasmussen et al. 2011). Intrusions in the MSM area belong to the Tay River suite and the southeast Tombstone-Tungsten belt (TTB) that comprises the Tungsten, Mayo, and Tombstone suites ( Fig. 13; Lang 2000; Selby et al. 2003;Hart et al. 2004a, b;Rasmussen et al. 2007Rasmussen et al. , 2010. The predominant forms of intrusion- related deposits associated with these plutonic rocks are divided into two broad categories ( Figs. 13 and 14; Hart et al. 2004a, b). The first group con- sists of skarn-related deposits that are proximal to, and ...
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... suite and the southeast Tombstone-Tungsten belt (TTB) that comprises the Tungsten, Mayo, and Tombstone suites ( Fig. 13; Lang 2000; Selby et al. 2003;Hart et al. 2004a, b;Rasmussen et al. 2007Rasmussen et al. , 2010. The predominant forms of intrusion- related deposits associated with these plutonic rocks are divided into two broad categories ( Figs. 13 and 14; Hart et al. 2004a, b). The first group con- sists of skarn-related deposits that are proximal to, and typically genetically related with, mainly the Tungsten suite and highly evolved phases of the Tay River suite. These skarns are mostly tungsten-rich (± minor Cu and/or Zn, Mo, Bi, and/or Au; Dick and Hodgson 1982;Bowman et al. 1985;Selby et al. 2003;Hart ...
Citations
... The Mackenzie Mountains comprise the western part of the Mackenzie Platform and the eastern part of the Selwyn Mountains; they are part of Ancestral North America, located on the western part of Laurentia (Nelson et al. 2013). There, they form the most northeastern extension of the Cordillera Ootes et al. 2013;Fig. 1). ...
... 1). Stratigraphically, rocks from the Neo-Proterozoic to the Cretaceous are preserved in the Anvil District (Faro, Grum, Swim, Dy, Vangorda) MacPass District (Tom, Jason) Gataga District (Cirque, Driftpile) Howards Pass (a) FIGURE 1. Simplified geologic maps of (a) the Selwyn Basin with Mackenzie carbonate platform and Mackenzie Mountains, and major mineral deposits (Goodfellow and Lydon 2007;Slack et al. 2016); and (b) the Mackenzie Mountains (Ootes et al. 2013 and references therein) with the Van Property (yellow star) of which a detailed geologic map is provided in Figure 2. ...
... Mackenzie Mountains. The Neo-Proterozoic strata include the older Mackenzie Mountains Supergroup (<1.05 and >0.78 Ga; Turner 2010; Gordey and Roots 2011;Long and Turner 2012) and the younger Windermere Supergroup (≈755 to 550 Ma; Narbonne and Aitken 1995; Gordey and Roots 2011;Ootes et al. 2013). The former consists of carbonate and clastic strata of 4 to 6 km thickness formed in deltaic, fluvial, and shelf settings of a large epicratonic basin (Rainbird et al. 1996;Long et al. 2008;Turner and Long 2008). ...
Shales and mudstones are fine-grained rocks formed in sedimentary basins throughout Earth’s history. These lithologies are increasingly important targets for mineral deposit exploration since they can have economic resources of critical minerals, including vanadium (V), an essential component of redox-flux batteries in solar cells. However, many Paleozoic, shale-hosted V deposits are metamorphosed and deformed. This commonly obscures primary features, including V-bearing host phases and the original composition of organic material.
In this study, we present geochemical and mineralogical data from the Paleozoic Van Property deposit, Northwest Territories, Canada, to show that V can be released from organic matter during metamorphism and incorporated in clay phases such as illite. The siliceous argillites at the Van Property host up to 0.69% V2O5 and were metamorphosed to (sub-)greenschist facies. Their mineralogy is dominated by quartz with minor graphite, illite, muscovite, pyrite, sphalerite, rutile, and carbonates. Although some illite (i.e., high-V illite) can have up to 13 wt% V2O3 and rutile can have up to 4.4 wt% V2O3, mass-balance calculations are insufficient to explain V enrichment at the Van Property utilizing only illite and rutile. The third V host is inferred to be carbonaceous matter in which V accumulated syn-deposition on the seafloor. Subsequent metamorphism led to the demetallation of V-bearing geoporphyrins and the release of vanadyl ions (VO²⁺), some of which were then incorporated into high-V illite and rutile. This process of V enrichment highlights the role of organic matter in scavenging V from superficial reservoirs and the importance of metamorphism on subsequent V release and its incorporation into inorganic phases. The geochemistry of siliceous, V-rich argillites at the Van Property is also compared to other V-enriched shale and mudstone deposits, highlighting the diversity of shale-hosted V deposits and emphasizing the need for further research to close the knowledge gaps related to variations in composition, mineralogy, and V enrichment processes.
... Though sporadic tarn lakes, meltwater lakes and smaller river systems litter individual study regions, the percentage of water accumulation areas is low. The dynamic sedimentary strata of the Mackenzie Mountains house a multitude of mineral deposits (Ootes et al. 2013). The susceptibility of sedimentary rock to weathering allows for ample debris supply for the development of rock glaciers, as does the accumulation of post-glacial till (Matsuoka and Ikeda 2001). ...
Rock glaciers have been the subject of extensive research in recent years due to their potential to serve as indicators of past and present climate conditions and their potential impacts on water resources. Location and descriptive rock glacier data within the Mackenzie Mountains were used to build a rock glacier inventory that will serve as a valuable resource for future research and monitoring efforts. Additionally, this study maps the likelihood of rock glacier presence using extracted variables in a generalized additive model (GAM). The model incorporates attribute data, including potential incoming solar radiation (PISR), topographic position index (TPI), slope, elevation, and lithology as controls for rock glacier development. Topographic data were compiled for three study regions of the Mackenzie Mountains from a 30 m digital elevation model (DEM). The analysis of the GAM showed that the most significant explanatory variables were PISR, elevation, slope, and TPI. The GAM model had an accuracy of 0.87 with a sensitivity of 0.92. This study provides important insights into the controls, distribution, and dynamics of rock glaciers in the Mackenzie Mountains, as well as both the limitations and the potential of statistical models in predicting their occurrence.
... Other deep-water basin and platform-hosted mineralization types in the Cordillera include 'hyper-enriched black shales' and 'sediment-hosted Cu' ('red-bed', or Kupferschiefertype'). Hyper-enriched black shales deposited off-shelf of the Laurentian margin (Kechika trough) in the Middle Devonian (Gadd et al., 2020(Gadd et al., , 2022b, can contain concentrations of Zn, Ni, Cu, Mo, Se, U, V, Cr, Co, Ag, Au, Re, PGE and REE, and Gadd et al. (2022b) described an example below younger SEDEX mineralization at the Akie deposit. Redbed copper deposits in marginal marine evaporites and related rocks of the Coates Lake Group (Neoproterozoic, Mackenzie Mountains, NT) display both syngenetic and epigenetic styles (e.g., Ootes et al., 2013;Brown et al., 2014) and there may be potential for this type of mineralization in Neoproterozoic units in northern British Columbia. Sedimentary or volcanic-hosted Cu mineralization also occurs in the Takla and Hazelton groups (Late Triassic to Early Jurassic) in eastern Stikine terrane (e.g., Sustut copper Consistent with the global distribution of such base metal deposits (Hoggard et al., 2020;Huston et al., 2023), SEDEX and MVT deposits in British Columbia formed in extensional tectonic settings, particularly related to the development of cratonic margins (e.g., Emsbo, 2009;Fig. ...
... The famous Sullivan deposit (Figs. 10, 12) formed in the deeper parts of the Belt-Purcell basin in an intracratonic sag generated by stretching of the Laurentian continental nucleus about 1.45 billion years ago (e.g., Lydon et al., 2000;Lydon, 2007). Early Paleozoic SEDEX and MVT deposits formed contemporaneously on the western flank of Ancestral North America during the breakup of the supercontinent Rodinia, suggesting a broad genetic relationship with regional platform to off-shelf fluid flow ( Fig. 2; e.g., Nelson et al., 2002Nelson et al., , 2013aOotes et al., 2013). ...
... Lead isotope studies suggest crustal sources of mineralization in MVT and SEDEX deposits (Godwin and Sinclair, 1982;Nelson et al., 2002;Leach et al., 2005;Ootes et al., 2013). Siliciclastic debris derived from continental basement and carbonate deposits are potential sources (Fig. 2b; Goodfellow and Lydon, 2007;Paradis et al., 2007;Emsbo et al., 2016;Leach et al., 2010). ...
... Other deep-water basin and platform-hosted mineralization types in the Cordillera include 'hyper-enriched black shales' and 'sediment-hosted Cu' ('red-bed', or Kupferschiefertype'). Hyper-enriched black shales deposited off-shelf of the Laurentian margin (Kechika trough) in the Middle Devonian (Gadd et al., 2020(Gadd et al., , 2022b, can contain concentrations of Zn, Ni, Cu, Mo, Se, U, V, Cr, Co, Ag, Au, Re, PGE and REE, and Gadd et al. (2022b) described an example below younger SEDEX mineralization at the Akie deposit. Redbed copper deposits in marginal marine evaporites and related rocks of the Coates Lake Group (Neoproterozoic, Mackenzie Mountains, NT) display both syngenetic and epigenetic styles (e.g., Ootes et al., 2013;Brown et al., 2014) and there may be potential for this type of mineralization in Neoproterozoic units in northern British Columbia. Sedimentary or volcanic-hosted Cu mineralization also occurs in the Takla and Hazelton groups (Late Triassic to Early Jurassic) in eastern Stikine terrane (e.g., Sustut copper Consistent with the global distribution of such base metal deposits (Hoggard et al., 2020;Huston et al., 2023), SEDEX and MVT deposits in British Columbia formed in extensional tectonic settings, particularly related to the development of cratonic margins (e.g., Emsbo, 2009;Fig. ...
... The famous Sullivan deposit (Figs. 10, 12) formed in the deeper parts of the Belt-Purcell basin in an intracratonic sag generated by stretching of the Laurentian continental nucleus about 1.45 billion years ago (e.g., Lydon et al., 2000;Lydon, 2007). Early Paleozoic SEDEX and MVT deposits formed contemporaneously on the western flank of Ancestral North America during the breakup of the supercontinent Rodinia, suggesting a broad genetic relationship with regional platform to off-shelf fluid flow ( Fig. 2; e.g., Nelson et al., 2002Nelson et al., , 2013aOotes et al., 2013). ...
... Lead isotope studies suggest crustal sources of mineralization in MVT and SEDEX deposits (Godwin and Sinclair, 1982;Nelson et al., 2002;Leach et al., 2005;Ootes et al., 2013). Siliciclastic debris derived from continental basement and carbonate deposits are potential sources (Fig. 2b; Goodfellow and Lydon, 2007;Paradis et al., 2007;Emsbo et al., 2016;Leach et al., 2010). ...
Mining is essential to produce the commodities needed to combat climate change. Low-carbon technologies need critical minerals to produce electric vehicles, mobile phones, solar panels, wind turbines, electrical transmission lines, batteries, and medical devices, and to manufacture products for national defense. Because of global demands, many of these critical minerals are predicted to see shortages, and British Columbia is faced with a generational opportunity for mining that will not only contribute to a low-carbon future but generate significant economic and societal benefits. Already mining critical minerals, British Columbia is Canada’s largest producer of Cu, only producer of Mo, mines Mg, ans recovers Zn, Ag, and Pb. Adopting a mineral systems approach, the British Columbia Geological Survey is engaging in field, laboratory, and mineral potential modelling studies to evaluate the critical mineral endowment of the province, clarify by- and co-production possibilities of critical minerals not being recovered from current base and precious metal mines, and serve the provincial Critical Minerals Strategy. Six mineral systems are of particular importance: porphyry; volcanogenic massive sulphide; deep-water basin and platformal base-metal; magmatic mafic to ultramafic; carbonatite, and iron skarn. Providing foundational geoscience data and developing novel exploration techniques will encourage discoveries and enhance exploration for underexplored mineral systems. By increasing awareness of critical mineral opportunities for the exploration and mining industries, and by enhancing the critical mineral knowledge base, the province seeks to encourage investment that could lead to new discoveries, expand existing resources, and make British Columbia a significant supplier of the raw materials necessary to address the climate crisis.
... The Cantung deposit is a W-Cu skarn hosted within Cambrian carbonate strata of the Selwyn Basin (Ootes et al., 2013), with mineralization occurring in two main ore bodies: the Open Pit orebody, and the underground E-zone orebody (Delaney and Bakker, 2014). Tungsten is present as scheelite in both orebodies, with abundant calcite (CaCO 3 ), dolomite (CaMg(CO 3 ) 2 ), pyrrhotite (Fe 1-x S), mica, and calc-silicate minerals. ...
Few studies have addressed the mobility of tungsten in mine waste, which could act as a point source for metal
leaching of this potentially toxic metal. This study examines the behavior of tungsten in acidic floodplain tailings
and circumneutral impoundment tailings at the Cantung Mine in the Northwest Territories, Canada. In the Cantung
deposit, tungsten is present as scheelite (CaWO4), copper is hosted in chalcopyrite (CuFeS2), and gangue
mineralogy consists of abundant pyrrhotite (Fe1-xS), silicate minerals, and carbonate minerals. Samples of surface
waters, tailings porewaters, and solid tailings samples were collected from Cantung Mine. For surface waters,
both filtered (0.45 μm) and unfiltered aliquots were collected to compare dissolved and particulate element concentrations.
Tungsten concentrations range from 5.8 to 30.0 μg/L in water samples with pH values between 7.1 and 8.1,
whereas samples below pH 7.1 have concentrations below the detection limit of 0.1 μg/L. Tungsten and iron concentrations
are both on average 1.7 times higher in unfiltered aliquots compared to filtered aliquots, suggesting
that tungsten is transported as dissolved species but is also adsorbed to suspended Fe-oxyhydroxide minerals at
neutral pH. Tailings were analyzed by scanning electron microscopy (SEM) paired with automated mineralogy
software (MLA), synchrotron-based μX-ray diffraction and fluorescence (μXRD-XRF), and partial leach digestions
with inductively coupled plasma mass spectrometry (cold and hot hydroxylamine hydrochloride, aqua regia, Limetaborate
fusion, and 4-acid digestion with HNO3-HClO4-HF-HCl). Samples from the impounded tailings and
the highly oxidized Flat River Tailings distributed on the floodplain (FRT) have similar scheelite content
(0.15 wt% and 0.21 wt%, respectively), and scheelite shows no evidence of alteration. Synchrotron-based μXRD
of Fe-oxyhydroxide minerals in the FRT identified goethite (FeOOH) and lepidocrocite (γ-FeOOH) as products of
pyrrhotite oxidation. Rare rims on pyrrhotite from the tailings impoundment have μXRD spectra consistent with
hematite (Fe2O3) and maghemite (γ-Fe2O3). The μXRF maps of the hematite-maghemite rims have prominent
tungsten peaks, which represent included scheelite grains and possibly structurally incorporated tungsten. The
hydroxylamine leaches yield higher tungsten concentrations in tailings samples from the circumneutral impoundments
than samples from the acidic FRT, suggesting the tailings impoundments have more tungsten that is
associated with poorly crystalline and amorphous Fe-oxyhydroxide phases than the FRT. Over time, labile-hosted
tungsten in the FRT may have been washed down the Flat River during Fe-oxyhydroxide recrystallization and
high energy flooding events. These results indicate that scheelite has limited solubility in neutral or acid mine
waters, and the mobility of the small amount of tungsten released is governed by the present of iron oxyhydroxide
minerals, the transport of colloidal material in surface water, and the stability of the depositional environment.
... The watershed is centered at approximately 512,170 m E, 6,897,916 m N (UTM); a large portion of which is located within the boundaries of the Nahanni and the Naats'ihch'oh National Park Reserves (Fig. 1). The Little Nahanni River watershed is found within the Mackenzie and eastern Selwyn Mountain ranges, at the northern limit of the Canadian Rocky Mountains (Ootes et al. 2013). The Little Nahanni River drains an area of approximately 1670 km 2 and is a branch of the headwater system for the South Nahanni River, a major tributary entering the Liard River which flows into the Mackenzie River system, into the Arctic Ocean. ...
Northern aquatic ecosystems face increasing pressures from climate change and natural resource development. The Arctic grayling (Thymallus arcticus) is a widely distributed, northern freshwater fish which can be vulnerable to such pressures. There remains a paucity of information on life stage requirements through most of the species’ range to reliably map and manage habitat to protect populations into the future. We sought to characterize fluvial Arctic grayling distribution among mountain streams and determine habitat characteristics and habitat use across life stages. Sampling was conducted at 183 sites across the Little Nahanni River watershed to collect information on fish distribution and reach-scale habitat parameters. Arctic graylings were collected for biological analyses of age, size, weight, and reproductive development. Based on age and size classes, there were four distinct post-emergence life stages: YOY, juvenile, sub-adult, and adult. YOY Arctic graylings were found exclusively in low elevation (< 1000 m) streams, flat-water habitat dominated by silty-sand substrate with average water temperatures > 10 °C. Similarly, juvenile Arctic graylings occupied low elevation, warm water stream habitat, but associated strongly with run habitats. Sub-adult Arctic graylings, the most widely distributed life stage, were found associated with riffle, pool, and cascade-boulder habitats. Adults occupied high-elevation (> 1200 m) habitats that were cold (mean stream temperature = 7 °C) and had higher proportions of pool and boulder habitats. The dynamic nature of Arctic grayling habitat use in mountain streams highlights the need to consider habitat complexes at the watershed scale when defining species life stage requirements, managing habitats, monitoring populations, and assessing potential impacts.
... The Selwyn basin is a complex, regionally deformed lower Paleozoic deep-water basin along the northwestern margin of ancestral North America (Gordey and Anderson 1993). Spanning from Alaska to British Columbia, the Selwyn basin contains pastproducing sedimentary exhalative/clastic-dominant (SEDEX/CD) base-metal deposits at several stratigraphic levels and carbonate-hosted Zn and Au deposits in surrounding shallow-water carbonate strata (Dewing et al. 2006;Ootes et al. 2013;Thiessen et al. 2016). The stratigraphically lowest SEDEX/CD deposits in the Selwyn basin, belonging to the past-producing Anvil district, were hosted by variably deformed and metamorphosed deep-water Cambrian strata (Pigage 2004;Goodfellow 2007). ...
The early evolution of the Misty Creek embayment (MCE), a prominent, northwest-trending sub-basin of the economically important Selwyn basin, is poorly understood. The abrupt contact between Cambrian Stage 4 (traditional lower Cambrian) carbonate ramp strata of the Sekwi Formation and overlying Miaolingian (traditional middle Cambrian) deep-water, calciturbiditic strata of the Hess River Formation has been regarded as diachronous. This important transition, which marks the onset of long-lived, deep-water conditions in the MCE, remains unexplained. This study uses biostratigraphic data from a previously undescribed location in the MCE, existing biostratigraphic and lithostratigraphic data from the 1970s, and regional thickness patterns to characterise the sharp yet diachronous transition from lithofacies typical of the Sekwi Formation to those typical of the Hess River Formation. The dramatic change in depositional environments was diachronous yet non-gradational, precluding a eustatic cause. The change was geologically abrupt, probably through two extension-related subsidence events, with different geographic extents, which heralded the MCE’s long life as a deep-water basin. The onset of deep-water conditions in the MCE occurred semi-contemporaneously with other extension-related events that are recorded in the northern Canadian Cordillera, demonstrating that Cambrian Series 2 – Miaolingian was a time of widespread extension and subsidence along the western margin of Laurentia.
... Formation of the basin stems from widespread protracted extensional tectonics of the Rodinian supercontinent that led to the re-emergence of the Laurentian craton between 825 and 740 Ma (Martel et al., 2011) with resulting development of the epicontinental margin and Selwyn Basin during the Ediacaran-Cambrian periods (Gordey, 1993). The oldest strata in the basin consist of the syn-rift Neoproterozoic-Terreneuvian Windermere Supergroup overlain by basinal post-rift Paleozoic sedimentary rocks with a combined total thickness of around 7,500 m (Ootes et al., 2013). Abrupt episodic extensions and volcanism during the Early Cambrian, Middle Ordovician, and Devonian are characterized by mafic volcanics within the platform carbonate and the basinal strata (Goodfellow and Lydon, 2007). ...
... A sudden change in depositional regime during the Late Devonian led to the deposition of siliciclastic sediments that spread from the margin of Laurentia toward the interior of the craton (Martel et al., 2011). Together with an overlying turbidite unit, the siliciclastic sediments are collectively known as the Earn Group ( Figure 1B; Gordey, 2013;Ootes et al., 2013). ...
... The red area in B depicts the current study location. (B) Devonian stratigraphic sequence of the Selwyn Basin from south to north (modified from Martel et al., 2011;Ootes et al., 2013;Morrow, 2018 In the Northwest Territories' part of the Selwyn Basin, 22-72 m thick barite sequences occur within stratigraphic sections at Bunk-2, Bunk-2, Cowan, NAFCAC-1, NAFCAC-2, Anita, Axe, Harp, and Wise locations (Figures 2, 3;Fernandes et al., 2017). These baritebearing sections occur as topographic highs, in a broad 200 km long NW-SE trend, are all confined to the upper parts of the Canol Formation, below the unconformity with the fine-grained siliciclastics of the Imperial Formation and are considered to be Frasnian in age (Martel et al., 2011;Fernandes et al., 2017). ...
The sulfur isotope composition of pyrite in marine sedimentary rocks is often difficult to interpret due to a lack of precise isotopic constraints for coeval sulfate. This study examines pyrite and barite in the Late Devonian Canol Formation (Selwyn Basin, Canada), which provides an archive of δ³⁴S and δ¹⁸O values during diagenesis. Scanning electron microscopy (SEM) has been combined with microscale secondary ion mass spectrometry (SIMS) analysis (n = 1,032) of pyrite (δ³⁴S) and barite (δ³⁴S and δ¹⁸O) on samples collected from nine stratigraphic sections of the Canol Formation. Two paragenetic stages of pyrite and barite formation have been distinguished, both replaced by barium carbonate and feldspar. The δ³⁴Sbarite and δ¹⁸Obarite values from all sections overlap, between +37.1‰ and +67.9‰ (median = +45.7‰) and +8.8‰ and +23.9‰ (median = +20.0‰), respectively. Barite morphologies and isotopic values are consistent with precipitation from diagenetically modified porewater sulfate (sulfate resupply << sulfate depletion) during early diagenesis. The two pyrite generations (Py-1 and Py-2) preserve distinct textures and end-member isotopic records. There is a large offset from coeval Late Devonian seawater sulfate in the δ³⁴Spyrite values of framboidal pyrite (-29.4‰ to -9.3‰), consistent with dissimilatory microbial sulfate reduction (MSR) during early diagenesis. The Py-2 is in textural equilibrium with barite generation 2 (Brt-2) and records a broad range of more positive δ³⁴SPy-2 values (+9.4‰ to + 44.5‰). The distinctive highly positive δ³⁴Spyrite values developed from sulfate limited conditions around the sulfate methane transition zone (SMTZ). We propose that a combination of factors, including low sulfate concentrations, MSR, and sulfate reduction coupled to anaerobic oxidation of methane (SR-AOM), led to the formation of highly positive δ³⁴Spyrite and δ³⁴Sbarite values in the Canol Formation. The presence of highly positive δ³⁴Spyrite values in other Late Devonian sedimentary units indicate that diagenetic pyrite formation at the SMTZ may be a more general feature of other Lower Paleozoic basins.
... Of the known Ag-bearing ore deposits in the region, only the Zn-Pb-Ag SEDEX 282 deposits of the Anvil District to the west in the Yukon, still in the Selwyn Basin, are 283 similar in age to the Rockslide Formation (Pigage, 1991;Ootes et al. 2013). The Ag 284 content in these deposits ranges from 36 to 84 g/t (Goodfellow 2007). ...
The Selwyn basin and Mackenzie platform of northwestern Canada house an array of mineral deposits and prospects that are rich in silver, including Neoproterozoic red-bed or Kupferschiefer-type Cu and lower Paleozoic sedimentary exhalative (SEDEX) and Zn–Pb deposits. Within this overall metallogenic setting, the middle Cambrian (Drumian) Rockslide Formation was deposited under a largely oxic water column on the platform-to-basin slope along the eastern side of the Selwyn basin. The formation includes an interval termed the Ravens Throat River Lagerstätte, which is a localized Burgess Shale-type calcareous mudstone about 2 m thick that preserves soft-bodied fossils. The mudstone contains comparatively large amounts of organic carbon preserved as thin carbonaceous laminae and discontinuous seams, representing benthic microbial mats, the remains of cyanobacteria and algae that were living in the water column, fecal pellets, large coprolites, and degraded animal tissues. The upper part of the Rockslide Formation, including the fossiliferous interval, contains elevated concentrations of Ag, up to 0.47 ppm. Some of the Ag in the mudstone occurs as aggregates of elemental particles ∼10 µm in size, preferentially on the carbonaceous material comprising the coprolites. This localized enrichment suggests bioaccumulation of Ag nanoparticles or Ag⁺ from the water column by microorganisms on the coprolites or degrading organic matter in them. The source of the Ag may have been from penecontemporaneous SEDEX metallogeny or from broadly related subsurface fluids in the Selwyn Basin that enriched the overlying seawater.
... Gayna River is a remote, undeveloped zinc camp (Northwest Territories, Canada; non-43-101-compliant resource of >50 Mt at >5% Zn + Pb; Hewton, 1982;Dewing et al., 2006;Ootes et al., 2013) hosted by carbonate strata of the mid-Neoproterozoic Little Dal Group (Mackenzie Mountains Supergroup; Fig. 1). Grid-based exploration drilling ( Fig. 4A) in the 1970s intersected abundant breccia-and vein-hosted sphalerite in dolostone of what is now known as the lower Gayna Formation (Turner and Long, 2012). ...
The predominant spatial control on sulfide orebodies at two significant base metal deposits, Kipushi (Democratic Republic of Congo) and Gayna River (Canada), is the architecture of Neoproterozoic carbonate lithofacies. At the Gayna River Zn camp, surface and subsurface mineralization is limited to the peripheries of giant pinnacle reefs of an unusual type hitherto considered unique. At the past-producing Kipushi Cu-Zn deposit, orebodies are associated with a lithologic break, until now interpreted as a fault but here reinterpreted as the steep depositional margin of a carbonate buildup similar to those at Gayna River. The zone of compositional and rheological contrast that generated where reef-flanking and overlying fine-grained terrigenous strata contact the Kipushi carbonate buildup appears to have focused later metalliferous fluid migration. This reinterpretation of two iconic deposits highlights the importance of considering sedimentary-stratigraphic controls on carbonate-hosted base metal deposits in mineral exploration programs.
