Southern Mackenzie Mountains Research Articles

Dall's sheep horn growth and harvest management in the Mackenzie Mountains, Northwest Territories, Canada

AbstractAcross most of their native North American range, the horns of mountain sheep (Ovis spp.) males are getting smaller, a pattern attributed to selective hunting pressure. We measured the horns of 755 Dall's sheep males (Ovis dalli dalli) in the southern Mackenzie Mountains, Northwest Territories, between 2002 and 2017. For each male, we measured the circumference and length of each annulus for the right horn and calculated horn volume for each year. We examined changes in horn size in 4 different outfitter areas, using age at harvest as a covariate. Hunting pressure across years in the study area was consistently low, and this population did not experience the decline in horn size observed in several other mountain sheep populations in Canada. Over the 16‐year period, the average horn volume of harvested males was stable and even increased in 1 outfitter area. Local management of Dall's sheep delivered independently by the guide outfitters in the Mackenzie Mountains appears to contribute to maintaining a population of males that has not been adversely affected by strong selective hunting pressure. The resilience of this management strategy may be challenged by environmental changes associated with rapid warming in northern mountain environments.

Cadmium and Mercury Exposure among Dene/Métis Communities of the Northwest Territories, Canada

In northern Indigenous communities, eating traditional foods (which include locally harvested wild game, fish, game birds, and plants) is associated with improved nutritional status. However, traditional foods can occasionally increase human exposures to contaminants. To mitigate potential risks from elevated contaminant levels in fish and wildlife, public health officials regularly respond to the results from environmental monitoring programs by designing notices that advise individuals to limit their consumption of particular traditional foods. For example, elevated mercury (Hg) levels in Walleye, Northern Pike, and Lake Trout in some subarctic lakes led to the release of a series of consumption notices by the Government of the Northwest Territories Department of Health and Social Services. Also, high levels of cadmium (Cd) in the organs of moose from the Southern Mackenzie Mountains, Canada resulted in consumption notices recommending people to limit their consumption of kidney and liver of moose harvested from this region.Since 2016, a community-based human biomonitoring project has been run in nine Dene/Métis communities of the Dehcho and Sahtú regions of the Northwest Territories Mackenzie Valley (n=538). This project included dietary assessments (e.g., 24-hour Recall, Food Frequency Questionnaire) as well as hair, urine and blood sampling to characterize contaminant exposures among participants. Although Hg and Cd levels in traditional foods from the Northwest Territories are occasionally elevated, the results from this biomonitoring research show exposures to these metals to be generally similar to those observed in other populations in Canada. These results are supporting ongoing efforts at the community and territorial level to design follow up plans in response to environmental monitoring data.

Investigation of Cadmium Exposure in Regards to Smoking Status and Moose and Caribou Organs Consumption in Northern Canada

Country food consumption among northern populations is associated with improved nutrition but occasionally can also increase contaminant exposure. Elevated cadmium levels in organs of moose harvested in the southern Mackenzie Mountains resulted in a food consumption notice by the Health and Social Services Department of the Northwest Territories, to recommend that people limit their consumption of liver and kidneys. Liver and kidneys of both moose and caribou are regularly consumed as country foods consumed in the Northwest Territories. The aim of this work is to report the levels and assess the determinants of cadmium exposures among communities of the Northwest Territories.The contaminants biomonitoring project includes dietary assessments (e.g. Food Frequency Questionnaire) and the collect of urine and blood samples. Participants were free to take part in any of the components of their choice (food questionnaires, hair/urine/blood sample). Cadmium was quantified using an inductively coupled plasma mass spectrometer (ICP-MS). The association between cadmium level, co-factors (age, sex) and potential sources (consumption of moose and caribou kidney and liver, smoking) were investigated.The 331 participants from the first 13 months of sample/data collection provided 144 blood and 127 urine samples. Participants who reported eating organs (liver, kidney) of moose and/or caribou did not have significantly higher cadmium levels. Instead, smoking status was significant determinant of cadmium levels in both blood (p<0.001) and urine (p=0.006). Results show cadmium levels similar to those observed in other populations in Canada.These results are supporting ongoing efforts to identify health priorities and plans in response to environmental monitoring data.

Geochemical and mineralogical controls on metal(loid) mobility in the oxide zone of the Prairie Creek Deposit, NWT

Prairie Creek is an unmined high grade Zn-Pb-Ag deposit in the southern Mackenzie Mountains of the Northwest Territories, located in a 320 km 2 enclave surrounded by the Nahanni National Park reserve. The upper portion of the quartz-carbonate-sulphide vein mineralization has undergone extensive oxidation, forming high grade zones, rich in smithsonite (ZnCO 3 ) and cerussite (PbCO 3 ). This weathered zone represents a significant resource and a potential component of mine waste material. This study is focused on characterizing the geochemical and mineralogical controls on metal(loid) mobility under mine waste conditions, with particular attention to the metal carbonates as a potential source of trace elements to the environment. Analyses were conducted using a combination of microanalytical techniques (electron microprobe, scanning electron microscopy with automated mineralogy, laser-ablation inductively-coupled mass spectrometry, and synchrotron-based element mapping, micro-X-ray diffraction and micro-X-ray absorbance). The elements of interest included Zn, Pb, Ag, As, Cd, Cu, Hg, Sb and Se. Results include the identification of minor phases previously unknown at Prairie Creek, including cinnabar (HgS), acanthite (Ag 2 S), metal arsenates, and Pb-Sb-oxide. Anglesite (PbSO 4 ) may also be present in greater proportions than recognized by previous work, composing up to 39 weight percent of some samples. Smithsonite is the major host for Zn but this mineral also contains elevated concentrations of Pb, Cd and Cu, while cerussite hosts Zn, Cu and Cd, with concentrations ranging from 6 ppm to upwards of 5.3 weight percent in the two minerals. Variable concentrations of As, Sb, Hg, Ag, and Se are also present in smithsonite and cerussite (listed in approximately decreasing order with concentrations ranging from <0.02 to 17 000 ppm). A significant proportion of the trace metal(loid)s may be hosted by other secondary minerals associated with mineralization. Processing will remove significant mineral hosts for these elements from the final tailings, although some may remain depending on whether the smithsonite fraction is left as tailings. Significant Hg and Ag could remain in tailings from cinnabar and acanthite that is trapped within smithsonite grains, which were found to act as a host for up to 53% of the Hg and 79% of the Ag contained in some samples. In a mine waste setting, near-neutral pH will encourage retention of trace metal(loid)s in solids. Regardless, oxidation, dissolution and mobilization is expected to continue in the long term, which may be slowed by saturated conditions, or accelerated by localized flow paths and acidification of isolated, sulphide-rich pore spaces. Supplementary material: Additional description of sampling and analytical methdologies are available at https://doi.org/10.6084/m9.figshare.c.3589562

Geochemical and mineralogical controls on metal(loid) dispersion in streams and stream sediments in the Prairie Creek district, NWT

The Prairie Creek district contains several types of carbonate-hosted Zn–Pb–Ag mineralization, including stratabound replacement sulphides, quartz-carbonate-sulphide veins, and classic Mississippi Valley-type. It is located in in the southern Mackenzie Mountains of northwestern Canada and within the boundaries of Nahanni National Park Reserve. The Prairie Creek district does not produce a strong geochemical signal in comparison to other mineralized areas of similar deposit types. Stream waters and sediments draining the district were sampled to determine the concentrations of Pb, Zn, Ag, As, Cd, Cu, Hg, Sb, and Se, and investigate the minerals hosting these elements, to investigate the geochemical controls on the mobility of these elements and any trends in dispersion. Results indicate that Zn and Pb are the most useful pathfinder elements, with anomalous concentrations in water downstream from Mississippi-Valley type mineralization and in sediments downstream from quartz-carbonate-sulphide vein mineralization. Zinc is more mobile than Pb, but elevated concentrations of neither element persist downstream of the metal source. Microanalytical examination of silt sediments indicate that Zn and Pb are associated with goethite and hematite, confirming active chemical weathering in this subarctic alpine environment.

The pattern and style of deglaciation at the Late Wisconsinan Laurentide and Cordilleran ice sheet limits in northeastern British Columbia

This paper reports on the landform assemblages at the northern confluence of the Late Wisconsinan Laurentide and Cordilleran ice sheets with montane and piedmont glaciers in the northern Rockies and southern Mackenzie Mountains. Recent observations in northeastern British Columbia refine our knowledge of the pattern and style of ice sheet retreat, glacial lake formation, and meltwater drainage. At the onset of deglaciation, confluent Laurentide and Cordilleran terminal ice margins lay between 59°N, 124°30′W and 60°N, 125°15′W. From this terminal limit, ice sheets retreated into north-central British Columbia and Yukon Territory, with remnant Cordilleran ice and montane glaciers confined to mountain valleys and the Liard Plateau. Distinctive end moraines are not associated with the retreat of Cordilleran ice in these areas. Laurentide ice retreated northeastward from uplands and the plateaus; then separated into lobes occupying the Fort Nelson and Petitot river valleys. Ice-retreat landforms include recessional end moraines (sometimes overridden and drumlinized), hill–hole pairs, crevasse-fill deposits, De Geer-like ribbed till ridges, hummocky moraines, kames, meltwater features, and glacial lake deposits that fall within the elevation range of glacial Lake Liard and glacial Lake Fort Nelson (ca. 840–380 m). Meltwater and sediment transport into glacial lakes Fort Nelson, Liard, Nahanni, and Mackenzie was sustained by remnant ice in the Liard River and Fort Nelson River drainage basins until the end of glaciation. Optical dating of sand from stabilized parabolic dunes on the Liard Plateau indicates that proglacial conditions, lake formation, and drainage began before 13.0 ± 0.5 ka (calendar years). The Petitot, Fort Nelson, and Liard rivers all occupy spillways incised into glacial deposits and bedrock by meltwater overflow from glacial lakes Peace and Hay.

Systematics of the Koneprusiine Trilobites, with new Taxa from the Silurian and Devonian of Laurentia

Abstract Systematics of the trilobite subfamily Koneprusiinae Vaněk and Pek, 1987 are revised on the basis of new material and a comprehensive parsimony analysis. New taxa include the genus Nevadaprusia (type species N. cortezensis n. sp.) from the Pragian of Nevada and the species Laethoprusia graffhami n. sp. from the Lochkovian of Oklahoma, L. cozarti n. sp. from the Lochkovian of Tennessee, and Laethoprusia n. sp. A from the Sheinwoodian of Arctic Canada and the southern Mackenzie Mountains. Nevadaprusia insolita (Haas) is revised on the basis of new material. Laethoprusia and Nevadaprusia are interpreted as sister taxa, and Koneprusia and Isoprusia are successive sister groups to the Laethoprusia/Nevadaprusia clade.

LATE ORDOVICIAN AND SILURIAN LICHID TRILOBITES FROM NORTHWESTERN CANADA: EIGHT NEW SPECIES FROM SUBFAMILIES LICHINAE, PLATYLICHINAE, AND TROCHURINAE

Eight new species of lichid trilobites representing five genera in three subfamilies, from the Avalanche Lake area of the southern Mackenzie Mountains, Northwest Territories, Canada, are described. The subfamily Lichinae is represented by Dicranopeltis n. sp. and the subfamily Platylichinae by the early Llandovery Platylichas infimus n. sp. The subfamily Trochurinae is represented by six species belonging to four genera. These are Acanthopyge (Lobopyge) sp. (Wenlock), the earliest known species of the genus Acanthopyge and subgenus Acanthopyge (Lobopyge), A. (L.) pristina n. sp. from the Glyptograptus persculptus Zone in the latest Ordovician, Dicranogmus lepidus n. sp., D. wilsoni n. sp. (both Wenlock), Dicranogmus n. sp. (Llandovery), and Radiolichas guttatus n. sp. (Wenlock).

Paucicanthus vanelstigen. et sp. nov., an Early Devonian (Lochkovian) acanthodian that lacks paired fin-spines

The acanthodian Paucicanthus vanelsti gen. et sp. nov. is described from six body fossils from Lower Devonian (Lochkovian) rocks of the southern Mackenzie Mountains, Northwest Territories, Canada. This new species is unique among acanthodians in that it lacks both pectoral and pelvic fin-spines. In the absence of fin-spines, the leading edges of the pectoral and pelvic fins are reinforced by enlarged scales. The anatomy of the acanthodiform Traquairichthys pygmaeus is similar to P. vanelsti in that both lack pelvic fin-spines, although T. pygmaeus also lacks pelvic fins. Similarly, the acanthodian Yealepis douglasi lacks both paired and median fin-spines, and its anatomy resembles that of P. vanelsti based only on the loss of paired fin-spines. The lack of paired and (or) median fin-spines in these three taxa contrasts with the widely held view that acanthodian fins all were preceded by spines. The anatomy of P. vanelsti also is similar to that of the acanthodian Brochoadmones milesi in that both have a completely unossified endoskeleton, slightly elevated pectoral fins, and deep, compressed bodies. The median fin-spines of P. vanelsti have an anterior leading edge rib followed by a field of fine striations. This striated ornamentation coupled with few leading edge ribs also is seen on fin-spines of Cassidiceps vermiculatus and primitive acanthodiform acanthodians (e.g., Mesacanthus and Lodeacanthus species). I tentatively suggest that this fin-spine ornament indicates relationship between P. vanelsti, acanthodiform acanthodians, and C. vermiculatus. However, a cladistic analysis is required to test whether or not the characteristics such as fin-spine loss, unossified endoskeleton, elevated pectoral fins, deep compressed bodies, and (or) median fin-spine ornamentation are synapomorphies within the Acanthodii or evolved convergently within the class.

New species of Silurian acanthodians from the Mackenzie Mountains, Canada

Two new acanthodian taxa are described. The ischnacanthid Xylacanthus kenstewarti is based on large, dentigerous jaws, and Granulacanthus joenelsoni is based on isolated spines. The isolated remains of these species are similar in that they both possess pustulose denticles or tubercles, either on the mesial ridge (X. kenstewarti) or on the fin spines (G. joenelsoni). Jaws of X. kenstewarti are similar in size to those of Xylacanthus minutus, Ischnacanthus kingi, and I. wickhami and smaller than those of X. grandis. The jaws of X. kenstewarti are most similar to those of X. minutus, but are distinguished from this and other ischnacanthid species by a tapering patch of pustulose denticles that is widest midway along the jaw, mesial denticles that are simple blisterlike structures, the monocuspid, striated primary teeth that are subcircular in cross section, and a posterodorsal process that is enlarged. The spines of G. joenelsoni have distinctive tubercular ornamentation. Tubercles, or nodular ornaments on fin spines, are characteristic of primitive acanthodians, but the slender shape of the spines, the low number of spine ribs, and the fine striations posterior to the main ribs of each spine suggest that G. joenelsoni is a relatively advanced acanthodian. Xylacanthus kenstewarti and G. joenelsoni are from the Silurian (Wenlock or Ludlow) of the southern Mackenzie Mountains. Xylacanthus kenstewarti represents the earliest representative of the genus, the earliest unequivocal remains of a gnathostome from the Mackenzie Mountains, and extends the known geographical range of the genus from the Mackenzie Mountains east to Spitsbergen.

Abstract :3-D Geometry of Compressional and Oblique Structures and Reactivated Normal Faults, southern Mackenzie Mountains, Canada

Abstract :3-D Geometry of Compressional and Oblique Structures and Reactivated Normal Faults, southern Mackenzie Mountains, Canada

Abstract: 3-D Geometry and Structural History of the Southern MacKenzie Mountains, Northwest Territories, Yukon and British Columbia, Canada

Abstract: 3-D Geometry and Structural History of the Southern MacKenzie Mountains, Northwest Territories, Yukon and British Columbia, Canada

Early Devonian cephalaspids (Vertebrata: Osteostraci: Cornuata) from the southern MacKenzie Mountains, N.W.T., Canada

ABSTRACT A diverse and well-preserved vertebrate fauna occurs in Early Devonian rocks of the Delorme Formation in the southern Mackenzie Mountains, Northwest Territories, Canada. The osteostracans of this fauna include the new cornuate species Waengsjoeaspis nahanniensis and Diademaspis? mackenziensis. Specimens of the latter species had been described in 1976 by Dineley and Loeffler as “Cephalaspis sp. indet.” The cornuate originally described as “?Cephalaspis gabrielsei” Dineley and Loeffler, 1976 is here assigned to the new genus Superciliaspis and more fully described. Other taxa include a possible example of Parameteoraspis sp. and several other indeterminate cornuates. Only dermal bone has been preserved, but preservation of its external and internal surfaces is excellent. Conspecific osteostracan specimens demonstrate a wide variety of overall proportions, due to differing amounts and directions of compaction. Some preferential orientation of corpses on bedding planes has been seen and several exam...

The aulacopleurid trilobite Otarion, with new species from the Silurian of northwestern Canada

The genus Otarion Zenker, 1833, first appears in the Wenlock simultaneously with Cyphaspis Burmeister, 1843, as the oldest known species of each occur together in the southern Mackenzie Mountains of the Canadian Northwest Territories. The genera are unambiguous sister groups, a relationship supported most compellingly by a uniquely derived and distinctive pattern of juvenile cephalic spines, shared also with the Carboniferous genus Namuropyge Richter and Richter, 1939. This sister group relationship permits the development of a robust and stratigraphically correlated hypothesis of relationship among the adequately known species of Otarion, Otarion, Cyphaspis, and Namuropyge constitute the tribe Otarionini. The Mississippian genus Dixiphopyge Brezinski, 1988, may also belong to Otarionini. Namuropyge is a paedomorph, likely derived from a Degree Six or Seven meraspid of an older species of uncertain position in the Otarion–Cyphaspis clade.Three Wenlock species of Otarion occur in stratigraphic succession in a single section in the Mackenzie Mountains. Analysis of morphological change with time, and of sequential ontogenies, suggests that the Silurian history of the genus was dominated by incidents of peramorphosis.New species are Otarion huddyi, O. beukeboomi, and O. coppinsensis. Otarion brauni Perry and Chatterton, 1979, is revised.

The peculiar Ordovician trilobite Hypodicranotus from the Whittaker Formation, District of Mackenzie

The complete exoskeleton of the widely dispersed remopleuridid trilobite Hypodicranotus is reconstructed for the first time based on well-preserved silicified material of Hypodicranotus striatulus (Walcott 1875) from the lower Whittaker Formation (Upper Ordovician, Edenian) of the southern Mackenzie Mountains. The minute oval pygidium consists of a single segment and, as such, it is the most reduced trilobite pygidium known. The subfamily Hypodicranotinae Přibyl and Vaněk is a junior synonym of the Remopleuridinae Hawle and Corda.

Silurian (Wenlock) brachiopods from the southern Mackenzie Mountains, Northwest Territories

Twelve species of brachiopods of probable Wenlock age are described from a fauna of approximately 39 species from the upper part of the Whittaker Formation of the southern Mackenzie Mountains. The fauna is probably from the near-platform-edge benthic setting and is numerically dominated by smooth-shelled pentamerids.Species described are ?Dolerorthis sp. 1, Epitomyonia triseptata Lenz, Leangella sp., Rugolepyros latispondylus n.gen., n.sp. (a probable pentamerid), Reveroides sp., Harpidium (Lissocoelina) sp., Lissidium erugata n.gen., n.sp. (pentamerinid), Gracianella lissubmra Johnson, Boucot and Murphy, ?Reticulatrypa sp. 1, Whitfieldella cf. upsilon (Barrande), Atrypina (Atrypinopsis) cf. biconvexa Rong and Wang, and Glassia biloba n.sp. (lissatrypid).

Upper Llandovery and Wenlock graptolites from Prairie Creek, southern Mackenzie Mountains, Northwest Territories

A moderately rich fauna of graptolites, comprising species dominated by Monograptus (sensu stricto), Retiolites, Stomatograptus, and Cyrtograptus is documented from Prairie Creek, southern Mackenzie Mountains, Northwest Territories. Graptolites of the upper Llandovery Monograptus turriculatus, Monograptus spiralis, and Cyrtograptus sakmaricus zones and of the Wenlock "unnamed zone" and Cyrtograptus rigidus and Monograptus testis – Cyrtograptus lundgreni zones are recognized. The species composition of these zones is significantly different from corresponding zones elsewhere in the Canadian Cordillera.Twenty-six species are described and illustrated, and of these, two are new: Stomatograptus canadensis and Cyrtograptus preclarus; and two species, Monograptus aff. riccartonensis and Cyrtograptus aff. sakmaricus might also be new. Several species, particularly Monograptus praecedens, Monograptus veles, and Monograptus cf. mutuliferus strigosus have not been prevously reported in North America.

An Ibexian (Early Ordovician) trilobite faunule from the type section of the Rabbitkettle Formation (southern Mackenzie Mountains, Northwest Territories)

The Rabbitkettle Formation is a widespread lower Paleozoic unit in the northern Cordillera. A trilobite faunule collected from the middle part of the type section and described here documents an early Ibexian (Early Ordovician) age for this interval and provides the first biostratigraphic reference point for the type section. This faunule is dominated by the agnostoid Micragnostus, the leiostegiid Leiostegium, and the remopleuridid Kainella. These genera and rarer taxa have North American, South American, and Austral-Asian affinities. A new species, Kainella eleutherolfi, is established.

Manetoe Facies--Gas-Bearing Late Diagenetic Dolomite of Northwest Territories, Canada: ABSTRACT

The white coarsely crystalline space-filling and replacement, late-diagenetic Mississippi Valley-type dolomite of the Manetoe facies occurs across a broad area of at least 15,000 sq km in the southern Mackenzie Mountains of the Northwest Territories. Through most of this area it is stratiform and confined to a thin (< 100 m thick) stratigraphic interval under a shale unit within a lower Paleozoic carbonate sequence. Some large vertical developments of the Manetoe facies, such as at the Kotaneelee and Pointed Mountain gas fields, occur in the eastern part of this region where the overlying shale of the Headless Formation is thin. These large dolomite masses have a core of dolomite-cemented breccia and are surrounded by a halo of replacement dolomite. Solution-collapse b eccias and large solution cavities are common throughout. Quartz and bitumen are the final vug infillings. The pronounced curvature of Manetoe dolomite crystal faces is similar to that displayed by many Mississippi Valley-type dolomites. These dolomites are nearly stoichiometric with a mean of 51 mole % CaCO3, and they exhibit a high degree of cation order. The range of carbon isotope values (+ 1.33 to -2.99 ^dgr C13PDB) and a sodium concentration of ~100 to 350 ppm are typical for this type of dolomite. But the range of oxygen isotope values (-8.03 to -17.33 ^dgrO18PDB), the extremely high strontium content of ~200 to 1,000 ppm, and an iron content less than 120 ppm is atypical and must reflect precipitation from a medium of unusual composition, enriched in strontium but depleted in iron and in the O18 isotope. End_of_Article - Last_Page 610------------

A cluster analysis interpretation of Middle Ordovician biofacies, southern Mackenzie Mountains

Collections of fossil trilobites, ostracods, bryozoans, and conodonts from Chazyan and Blackriveran strata of the southern Mackenzie Mountains are analyzed in an attempt to define biofacies, in terms of areal extent and faunal composition. Q-mode and R-mode cluster analyses, using Jaccard's coefficient and the unweighted pair-group method of clustering, are employed to delineate five biofacies. The interpretation of sedimentological features and composition of faunal assemblages shows that one nearshore biofacies, three progressively deeper shelf biofacies, and one continental slope biofacies are represented. A plot of biofacies succession through time in each measured section provides added support for the biofacies interpretations.