Bathurst Inlet Research Articles

New distribution records of kelp in the Kitikmeot Region, Northwest Passage, Canada, fill a pan-Arctic gap

Kelps play important roles in ecosystems as they provide structural habitat and protection, and supply food. Given these beneficial roles and observed increases in seaweed biomass and distribution ranges across the Arctic, mapping kelp occurrence around Arctic coasts is both timely and necessary for future conservation. Here, we fill spatial gaps in the knowledge of kelp distribution in the southern Northwest Passage, Canadian Arctic Archipelago; specifically, we report the occurrence of Laminaria solidungula, Saccharina latissima and Alaria esculenta from Victoria and Dease straits and Bathurst Inlet in the Kitikmeot Region at depths mostly from 10 to 30 m (max. 40 m; upper extent vessel-limited). Kelp specimens were found at bottom water temperatures from sub-zero to 1 °C (surface-T to ~ 6 °C) and bottom water salinities of ~ 28 (surface-S < 20) in August–September. Kelp sites were characterized by both strong tidal currents (max. estimates from a tidal model 20–70 cm s−1 in center of passages) and hard substrates, interspersed with finer sediments. Co-occurring identifiable epibenthos was dominated by suspension-feeders preferring currents (sea cucumbers, soft corals, Hiatella clams), potential kelp consumers (sea urchins Strongylocentrotus sp., Margarites snails, limpets) and predatory invertebrates (sea stars, lyre crabs). At the same and some deeper nearby sites, loose kelp fragments were also found at the seabed, suggesting that kelps contribute to the regional detrital food web by supplying carbon to less productive sites. Kelps in the region may expand their ranges and/or growing season with reduced ice cover and warming, although constraints through local turbidity sources, extreme temperatures, low salinity and low nutrient concentrations are also recognized.

Origin and composition of three heterolithic boulder- and cobble-bearing deposits overlying the Murray and Stimson formations, Gale Crater, Mars

Heterolithic, boulder-containing, pebble-strewn surfaces occur along the lower slopes of Aeolis Mons (“Mt. Sharp”) in Gale crater, Mars. They were observed in HiRISE images acquired from orbit prior to the landing of the Curiosity rover. The rover was used to investigate three of these units named Blackfoot, Brandberg, and Bimbe between sols 1099 and 1410. These unconsolidated units overlie the lower Murray formation that forms the base of Mt. Sharp, and consist of pebbles, cobbles and boulders. Blackfoot also overlies portions of the Stimson formation, which consists of eolian sandstone that is understood to significantly postdate the dominantly lacustrine deposition of the Murray formation. Blackfoot is elliptical in shape (62 × 26 m), while Brandberg is nearly circular (50 × 55 m), and Bimbe is irregular in shape, covering about ten times the area of the other two. The largest boulders are 1.5–2.5 m in size and are interpreted to be sandstones. As seen from orbit, some boulders are light-toned and others are dark-toned. Rover-based observations show that both have the same gray appearance from the ground and their apparently different albedos in orbital observations result from relatively flat sky-facing surfaces.Chemical observations show that two clasts of fine sandstone at Bimbe have similar compositions and morphologies to nine ChemCam targets observed early in the mission, near Yellowknife Bay, including the Bathurst Inlet outcrop, and to at least one target (Pyramid Hills, Sol 692) and possibly a cap rock unit just north of Hidden Valley, locations that are several kilometers apart in distance and tens of meters in elevation. These findings may suggest the earlier existence of draping strata, like the Stimson formation, that would have overlain the current surface from Bimbe to Yellowknife Bay. Compositionally these extinct strata could be related to the Siccar Point group to which the Stimson formation belongs.Dark, massive sandstone blocks at Bimbe are chemically distinct from blocks of similar morphology at Bradbury Rise, except for a single float block, Oscar (Sol 516). Conglomerates observed along a low, sinuous ridge at Bimbe consist of matrix and clasts with compositions similar to the Stimson formation, suggesting that stream beds likely existed nearly contemporaneously with the dunes that eventually formed the Stimson formation, or that they had the same source material. In either case, they represent a later pulse of fluvial activity relative to the lakes associated with the Murray formation.These three units may be local remnants of infilled impact craters (especially circular-shaped Brandberg), decayed buttes, patches of unconsolidated fluvial deposits, or residual mass-movement debris. Their incorporation of Stimson and Murray rocks, the lack of lithification, and appearance of being erosional remnants suggest that they record erosion and deposition events that post-date the exposure of the Stimson formation.

Marine zooplankton of Coronation Gulf and Bathurst Inlet, Nunavut, Canada

Here we report a survey of marine zooplankton in Coronation Gulf and Bathurst inlet located in the Kitikmeot Region of Nunavut, Canada. Zooplankton were collected at nineteen stations with a 236 μm mesh net in September 2007. The zooplankton samples were examined for species composition, abundance and spatial heterogeneity. Taxa were characteristic of the Arctic zooplankton fauna but not distributed homogeneously. Overall, from west to east, the abundance of cyclopoid and harpacticoid copepods decreased as calanoid copepods increased. Multivariate cluster analysis revealed 5 sub-groups based on species composition and abundance which are located in West, Central, and Eastern Coronation Gulf, and mid- and southern Bathurst Inlet. The West group had three stations and a high number of the cyclopoid copepods Oithona similis and Triconia borealis. The Central group contained six stations, which were distinguished as having a mixture of Oithona and juvenile Pseudocalanus as well as high percentage of Calanus juveniles. One station of the Central group was found in northeastern Dolphin and Union Strait likely tracing the outflow of water from Coronation Gulf. The Eastern group had a high number of Pseudocalanus and Acartia juveniles. Acartia hudsonica, Eurytemora, and Tortanus discaudatus were found in Bathurst Inlet in association with conditions created by riverine freshwater input. Also, a high number of bivalve veligers were observed in the southern reaches of Bathurst Inlet. This report describes a heterogeneous distribution of typical Arctic zooplankton taxa in the region and serves as a baseline from which to measure change.

Assessing the Potential to Operationalize Shoreline Sensitivity Mapping: Classifying Multiple Wide Fine Quadrature Polarized RADARSAT-2 and Landsat 5 Scenes with a Single Random Forest Model

The Random Forest algorithm was used to classify 86 Wide Fine Quadrature Polarized RADARSAT-2 scenes, five Landsat 5 scenes, and a Digital Elevation Model covering an area approximately 81,000 km2 in size, and representing the entirety of Dease Strait, Coronation Gulf and Bathurst Inlet, Nunavut. The focus of this research was to assess the potential to operationalize shoreline sensitivity mapping to inform oil spill response and contingency planning. The impact of varying the training sample size and reducing model data load were evaluated. Results showed that acceptable accuracies could be achieved with relatively few training samples, but that higher accuracies and greater probabilities of correct class assignment were observed with larger sample sizes. Additionally, the number of inputs to the model could be greatly reduced without impacting overall performance. Optimized models reached independent accuracies of 91% for seven land cover types, and classification probabilities between 0.77 and 0.98 (values for latter represent per-class averages generated from independent validation sites). Mixed results were observed when assessing the potential for remote predictive mapping by simulating transferability of the model to scenes without training data.

The Canadian Arctic Expedition 1913–18 and Early Advances in Arctic Vertebrate Zoology

A century ago, an international team of scientists sailed under the Canadian flag to the western Canadian Arctic, via the Bering Strait, to achieve the goals of the Canadian Arctic Expedition of 1913–18. This major expedition was a milestone in the history of Canada. The scientists explored a vast, unknown sea and land area that extended from the Alaskan northern coast to Bathurst Inlet in Canada, and from Meighen Island to approximately 160 – 200 km inland from the continental coasts. This area had never been explored by an expedition before, and many parts of it had never been visited (except, presumably, by Inuit and their ancestors). The expedition resulted in a remarkable harvest of terrestrial and marine plants and animals, and associated data. The scientists furthered geographic and scientific knowledge of the Arctic and published 74 reports in various scientific fields, yet none of these addressed vertebrate zoology. The present report attempts to make up for this deficiency. Overall, the CAE collected and preserved 2084 vertebrate specimens and inventoried 139 species, which together fairly depicted the Arctic vertebrate community. Almost all specimens are preserved at the Canadian Museum of Nature. They significantly supplemented the rather meagre vertebrate collections of the Museum of those times and have since prompted the continuing development of these collections.

Survival and nesting success of the Pacific Eider (Somateria mollissima v-nigrum) near Bathurst Inlet, Nunavut

We used resighting data from 242 individually marked females to estimate apparent survival of Pacific Eiders ( Somateria mollissima v-nigrum Bonaparte, 1855) at a nesting colony in central arctic Canada from 2001 to 2007. In addition, we used data from nest searches conducted on islands at a freshwater lake and an adjacent marine environment to estimate annual breeding success. Annual survival rate estimates ranged from 0.84 ± 0.04 (mean ± SE) to 0.86 ± 0.05. Mayfield estimates of nest success ranged from 48.8% to 68.1% at the freshwater colony, and from 13.9% to 43.5% at the marine nesting colonies. The overwhelming cause of nest failure at both nesting areas was predation by grizzly bear ( Ursus arctos horribilis Ord, 1815), arctic fox ( Vulpes lagopus (L., 1758)), and wolverine ( Gulo gulo (L., 1758)). The majority of nests were initiated prior to ocean ice breakup in mid-July, thus mammalian predators had access to the islands well into incubation. Our results suggest that during the period from 2001 to 2007, the population of Pacific Eiders was likely not in decline. Therefore, the marked decline observed for eiders migrating past Point Barrow, Alaska, from 1976 to 1996 was more likely attributable to a stochastic event, such as unfavourable ice conditions, than to a chronic factor.

Tundra Game Drives: an Arctic-Alpine Comparison

Stone fences and blinds built by prehistoric hunters to gather and ambush elk and bighorn sheep above timberline in the Colorado Front Range are similar in concept and function to structures built by the Copper Inuit and their predecessors for hunting caribou near Bathurst Inlet, in the Central Canadian Arctic. Four principal differences exist: (1) Circular blinds and continuous rock walls are more numerous in the Front Range than in the Arctic, where arcuate breastworks and lines of widely spaced cairns predominate. Differences in prey-species behavior are the most probable explanation. (2) Stone house foundations, meat-drying facilities, meat caches, kayak-storage racks, and fox and wolf traps occur near drive sites along caribou migration routes in the Bathurst Inlet region. The structures imply long-term habitation made possible by a plentiful meat supply. Comparable structures are absent above timberline in the Front Range because people retreated to warmer environments in winter, and because steep terrain and deep snow discouraged return visits to high-altitude caches. (3) The technique was adopted much earlier in Colorado than in the Central Canadian Arctic. The oldest Front Range drive systems were constructed while the Laurentide Ice Sheet still covered the Bathurst Inlet landscape. (4) Pedestrian game-drive hunting was abandoned in the Front Range soon after arrival of the horse (ca. a.d. 1700), but remained an integral part of Copper Inuit subsistence until the mid twentieth century. The rich ethnographic and oral history record of communal hunting in the Arctic is invaluable for interpreting the Colorado structures.

Multi-criteria evaluation and least cost path analysis for an arctic all-weather road

Increasing interest in the development of the base metal, gold, and diamond resources in the Slave Geological Province in Nunavut has led to the proposal that a deep-water port be constructed in Bathurst Inlet and connected to these mining regions by an all-weather road. In response to previous concerns regarding the subjectivity of existing techniques for route determination, this paper outlines a methodology for determining a least-cost-path for the route of an all-weather road that incorporates multi-criteria analysis. This methodology allows for the objective comparison of alternate scenarios for weighting the factors that determine the location of a road's route. The methodology is applied, using three alternate scenarios for road construction that are compared so as to determine the effectiveness and sensitivity of this approach. The strengths and limitations of this methodology are discussed.

An arctic terrestrial food-chain bioaccumulation model for persistent organic pollutants.

A model representing the bioaccumulation of persistent organic pollutants (POPs) in arctic terrestrial mammalian food-chains is developed, parametrized, tested, and analyzed. The model predicts concentrations of POPs in lichen, caribou (Rangifer tarandus), and wolf (Canis lupus) food-chains of Canada's central and western arctic region from measured concentrations in air and snowpack meltwater. The model accounts for temporal and seasonal variation in diet composition, life-stage, body weight, and fat content over the life-span of the animal. Model predicted concentrations of 25 organic chemicals forecasted for caribou and wolves from Cambridge Bay (69 degrees 07' N 105 degrees 03' W), Inuvik (68 degrees 18' N 133 degrees 29' W) and Bathurst Inlet (64 degrees 15' N 113 degrees 07' W) are shown to be in good agreement with the observed data. The model illustrates a strong relationship between biomagnification factors and chemical K(OA) and illustrates the effect of age, sex, and temperature on POPs bioaccumulation. Model results show that POPs with K(OA)s < 10(5) do not biomagnify in arctic terrestrial food-chains, while substances that exhibit log K(OA)s > 5 and also exhibit a log K(OW) > 2, show significant bioaccumulation in arctic terrestrial food-chains. The model shows that persistent low K(OW) (K(OW)s < 10(5)) but high K(OA) substances such as beta-HCH, 1,2,4,5 tetrachlorobenzene, and beta-endosulfan biomagnify in terrestrial mammals.

The Hiukitak School of Tuktu: Collecting Inuit Ecological Knowledge of Caribou and Calving Areas Through an Elder-Youth Camp

... this paper is the first formal report of the elder-youth camp recently held at the Hiukitak River near Bathurst Inlet in the Kitikmeot region. I begin by providing a background on the methods used in developing the project, focusing on how the research and research team developed, and why the camp became a key component of the methods. Next, I show how a camp can be a reliable, effective and fun way to record and communicate Inuit ecological knowledge (IEK). Throughout this section, I explore gender-related differences in expertise about caribou. ...

The Tuktu and Nogak Project: Inuit Knowledge about Caribou and Calving Areas in the Bathurst Inlet Region

... Traditional ecological knowledge is central to Inuit culture in general, and to the sustainable management of lands, resources, and wildlife in particular. Since lifestyles in the Bathurst Inlet region are changing at the same time that elders are passing on and taking their wisdom with them, efforts to document this knowledge are critical. Mineral exploration and the potential for mine development, along with other land use issues, further compound this imperative. For these reasons, a two-year study entitled The Tuktu (caribou) and Nogak (calves) Project (the project) was initiated in February 1997, with the primary goal of documenting and communicating Inuit knowledge about caribou and calving areas in the Bathurst Inlet region. ...

Late Quaternary sea level history in the Paulatuk to Bathurst Inlet area, Northwest Territories

The Paulatuk – Bathurst Inlet region experienced rapid deglaciation in response to marine incursion across isostatically depressed terrain during high relative sea level stands. Marine limits, frequently defined by ice-contact deltas, range from 10 m asl in the west to 228 m asl in the east and were formed from approximately 12.5 to 9 ka BP, respectively. Seven relative sea level curves demonstrate that the mainland coast has shown initial rapid emergence, then progressively less emergence, and finally submergence from Paulatuk to Bernard Harbour during the late Holocene. Regions to the east (Richardson Bay to Bathurst Inlet) continue to experience emergence. Sea level curves have shown persistently higher rebound from west to east. The pattern and magnitude of observed postglacial sea level changes are in accord with theoretical predictions. In areas outside the glacial limit, as well as close to but within the glacial limit, relative sea level initially falls during the early and middle Holocene, and then begins to rise due to the migration of the forebulge in late Holocene times. Submergence becomes progressively younger from west to east. Closer to the centre of ice loading, emergence has progressed since deglaciation.

Extralimital occurrences of Beluga, Delphinapterus leucas, and Walrus, Odobenus rosmarus, in Bathurst Inlet, Northwest Territories

Extralimital occurrences of Beluga, Delphinapterus leucas, and Walrus, Odobenus rosmarus, in Bathurst Inlet, Northwest Territories

Macrolichens of the Coppermine, Hood, and Thomsen Rivers, Northwest Territories, Canada

One hundred and sixty-three taxa of foliose and fruticose lichens are reported from three regions of the Canadian Arctic. The northernmost collecting region, and that with the most severe climate, is the Thomsen River valley on Banks Island. Also included are the Hood River valley, entirely north of the arctic treeline, and the Coppermine River valley, which flows northward through the forest-tundra border. Newly reported for Banks Island are Cladonia alaskana, Peltigera rufescens, Solorina bispora, S. saccata, and Vulpicida pinastri. Of these Jive, C. alaskana and V. pinastri have not previously been reported on any of the arctic islands. The macrolichen flora of these areas consists primarily of wide-ranging arctic-alpine and arctic-boreal species. This study was undertaken in order to increase the understanding of the distributions of the foliose and fruticose lichens in the areas surrounding the Coppermine, Hood, and Thomsen Rivers in the Northwest Territories of Canada. No complete col- lections have been made along the lengths of these rivers although some have been done at the mouth of the Coppermine (Thomson 1970), in the Bathurst Inlet area (Thomson & Scotter 1983), and along the upper Coppermine to the Kendall River junction (Robinson et al. 1989). The study area is located in the central Canadian arctic (Fig. 1) and includes areas from the northern edge of the boreal forest to the southern edge of the high arctic. METHODS Field work was done during the summers of 1990 and 1991, with collections being made at 25 localities. Eight localities were along the Coppermine River, three along the Thomsen River, and 14 along the Hood River (Fig. 1). Collecting was done concurrently with teaching a field course for the University of Colorado. Travel was down- stream by inflatable kayak. Collections from each river were loosely stored in waterproof packs and carried for the duration of each month-long trip. A total of 2,147 specimens were collected. Localities were chosen to in- clude areas with internal homogeneity of vegetation type, with an attempt to collect in as many habitats as were encountered.

Nature and timing of Franklin igneous events, Canada: Implications for a Late Proterozoic mantle plume and the break-up of Laurentia

U Pb baddeleyite/zircon ages have been determined for gabbro sills and diabase dykes emplaced during Franklin igneous events in northern Canada. Results for seven widely separated sills from Victoria Island, Coronation Gulf and Bathurst Inlet, and for a single diabase dyke from southeastern Baffin Island, indicate that most of the Franklin igneous activity was synchronous and occurred at 723 + 4/−2 Ma. A U Pb baddeleyite/ zircon age of 718 ± 2 Ma for one of the Victoria Island sills suggests that the magmatism continued for at least 5 m.y. after the initial outburst. The short-duration and large volume of the intrusive tholeiitic magmatism and its association with the Natkusiak flood basalts suggest a link with a mantle plume-generated hotspot. The onset of magmatism may have coincided with the arrival of the plume at the base of the lithosphere. Stratigraphic relationships on Victoria Island indicate that differential uplift occurred just prior to the initial outbreak of igneous activity, which is interpreted as a response to doming above the upwelling plume. The exposed record provides no indication of significant pre-volcanic extension and rifting, although some NE-SW extension occurred after the initial eruptive phase. The 779 Ma mafic magmatism in the Mackenzie Mountains, the 723 Ma Franklin events and the 615 Ma Long Range dykes in Labrador are three precisely dated mafic events in North America that may be contemporaneous with various phases of Late Proterozoic break-up of Laurentia. These ages establish key chronological constraints for global correlation of Late Proterozoic epicontinental basins and for Precambrian plate reconstructions.

A middle Proterozoic palaeokarst unconformity and associated sedimentary rocks, Elu Basin, northwest Canada

ABSTRACTA major palaeokarst erosion surface is developed within the middle Proterozoic Elu Basin, northwestern Canada. This palaeokarst is named the sub‐Kanuyak unconformity and truncates the Parry Bay Formation, a sequence of shallow‐marine dolostones that were deposited within a north‐facing carbonate platform under a semi‐arid climate.The sub‐Kanuyak unconformity exhibits up to 90 m of local relief, and also formed under semi‐arid conditions when Parry Bay dolostones were subaerially exposed during a relative sea‐level drop of about 180 m. Caves and various karren developed within the meteoric vadose and phreatic zones. Their geometry, size and orientation were largely controlled by northwest‐ and northeast‐trending antecedent joints, bedding, and lithology. Near‐surface caves later collapsed forming valleys, and intervening towers or walls, and plains. Minor terra rossa formed on top of highs. Karstification was most pronounced in southern parts of Bathurst Inlet but decreased northward, probably reflecting varying lengths of exposure time along a north‐dipping slope.The Kanuyak Formation is up to 65 m thick, and partially covers the underlying palaeokarst. It consists of six lithofacies: (i) breccia formed during collapse of caves, as reworked collapse breccia and regolith; (ii) conglomerate representing gravel‐dominated braided‐fluvial deposits; (iii) sandstone deposited as braided‐fluvial and storm‐dominated lacustrine deposits; (iv) interbedded sandstone, siltstone and mudstone of sheet flood origin; (v) dolostones formed from dolocretes and quiet‐water lacustrine deposits; and (vi) red‐beds representing intertidal‐marine mudflat deposits. Rivers flowed toward the northwest and northeast within karst valleys and caves; lakes were also situated within valleys; marine mudflat sediments completely cover the palaeokarst to the north.A regional correlation of the sub‐Kanuyak unconformity with the intra‐Greenhorn Lakes disconformity within the Coppermine homocline suggests that similar styles of karstification occurred over an extensive region. The Elu Basin palaeokarst, however, was developed more landward, and was exposed for a longer period of time than the Coppermine homocline palaeokarst.

Recovery of Tundra Vegetation after Overgrazing by Caribou in Arctic Canada

During the summer of 1987, 500-1000 caribou became stranded on Rideout Island in Bathurst Inlet, Northwest Territories. The 40 sq/km island did not have sufficient forage to support the animals until freeze-up, and the caribou eventually died from malnutrition after severely overgrazing the vegetation. In late July 1988, we found that most of the vascular vegetation on Rideout Island had recovered considerably. Vascular species composition and cover in the two major plant communities were comparable to those in similar communities on the adjacent, moderately grazed mainland. The willows (Salix spp.) and graminoid species were vigorous, and no differences were found in biomass allocation patterns of Salix lanata plants between the island and the mainland. However, essentially all of the macrolichen biomass was eliminated on the island, and full recovery could take more than 20 years.Key words: caribou, caribou range ecology, overgrazing, Bathurst Inlet, arctic vegetation, Salix spp., Betula spp.

Was the coppermine homocline of northwestern Canada uplifted as part of a Middle Proterozoic forebulge

Application of the principles of elastic plate bending to subsurface geometric information and outcrop in northwestern Canada suggests that Proterozoic crust was loaded and deflected during orogenic activity between about 1.6 and 1.1 Ga. Exposed Hudsonian (ca. 1.8–2.0 Ga) basement separating younger but coeval stratigraphic sequences in the Coppermine Homocline on the west and Bathurst Inlet on the east can be explained as a forebulge associated with the loading.

Dolomitized Middle Proterozoic Calcretes, Bathurst Inlet, Northwest Territories, Canada

ABSTRACT Dolostones within the terrigenous clastic middle Proterozoic Kanuyak Formation are interpreted to be dolomitized calcretes (dolocretes) which formed on a landscape largely devoid of macroscopic organic life. The dolocretes up to 5 m thick form beds or masses which either parallel or cross-cut host sedimentary rocks, and are composed of five elements: 1) curvilinear and rectilinear networks of cracks which are filled with detrital terrigenous clastic and carbonate sediments, ooids, pisoids and cements (sediments and cements are laminated and bedded, generally parallel to the margins of cracks); 2) micritic, fibrous, columnar and plumose dolomitic cements that were precipitated as calcareous speleothems, ooids and pisoids, and masses; 3) ooids and pisoids that are concentrically-laminat d, homogenous or coated grains occurring in reversely-graded beds and as isolated particles throughout dolocretes (it appears that accretionary particles formed in situ based upon polygonal fitting, vadose and grapestone fabrics, and gradational contacts between ooids/pisoids and host sediments); 4) deformation structures that include folded and brecciated detrital sediments within cracks, brecciated pisoids and minor teepees; and 5) surface karren that locally truncate the dolocretes. While missing the features commonly associated with higher plants in post-Silurian calcretes (rhizoconcretions, root-mouldic porosity, etc.), the presence of an array of other common calcrete fabrics (e.g., cracks, cements, accretionary grains and deformation structures) suggests that physical and chemical processes were probably largely responsible for the carbonate precipitates within Kanuyak profiles. Microbiota most likely also contributed to calcretization; however, if not significantly altered by dolomitization, stable carbon and oxygen isotope values do not indicate any significant influence by organic matter.

A zoned low P-high T complex at the level of anatexis—structural and plutonic patterns in metasediments of the Archean Yellowknife Supergroup, near Bathurst Inlet, N.W.T., Canada

Within metagreywackes and schists of the Archean Yellowknife Supergroup the development of an “anatectic stratigraphy” during the late stages of regional deformation has resulted in the formation of a complex with a metamorphicplutonic-structural zoning similar to that occurring in Phanerozoic low P-high T terrains. From bottom to top the “stratigraphy” consists of: (1) small-folded migmatite, grading with decreasing partial melting to (2) sillimanite schist, strongly strained by the emplacement of two-mica granites; (3) andalusite-cordierite schist, the site of large folds related to the emplacement of the complex. Each zone is characterized by a different structural style resulting from the interplay between metamorphic grade and deformation. For instance in the sillimanite zone, the structure was influenced by the extraction of syntectonic melt and its emplacement into fractures at low effective pressure. This zone was also the ductile envelope into which sills and plutons of two-mica granites derived from the lower migmatites migrated. The time taken for evolution of the complex has been constrained by U-Pb zircon and monazite dating of a member of the early tonalite-diorite suite and members of the two-mica granite suite. This shows the evolution of the complex was rapid, ca. 10 Ma, but possibly polyphase. The formation of a distinctively styled complex accompanied by syn-tectonic anatexis and plutonism, may be typical of lower crustal levels of the Yellowknife Supergroup and other low P-high T terrains.