RESEARCH

Provenance approaches in polydeformed metasedimentary successions: Determining nearest neighboring cratons during the deposition of the Paleoproterozoic Murmac Bay Group

C. Shiels, C.A. Partin, and B.M. Eglington DEPARTMENT OF GEOLOGICAL SCIENCES, UNIVERSITY OF SASKATCHEWAN, 114 SCIENCE PLACE, SASKATOON, SASKATCHEWAN S7N 5E2, CANADA

ABSTRACT

The proximity and positions of cratons constituting the western Canadian Shield prior to and during the Rhyacian Period (2.30–2.05 Ga) are poorly known. In the absence of paleomagnetic data, stratigraphic correlation and detrital zircon isotopic data from sedimentary suc- cessions can be used to constrain relative craton positions during their time of deposition. The Murmac Bay Group, a multiply deformed meta­sedimentary succession located on the Rae craton margin in Canada, provides an opportunity to test hypotheses regarding its nearest cratonic neighbors during deposition. The polydeformed nature of the Murmac Bay Group, however, presents challenges in determining detailed stratigraphic relationships in the upper succession, which lacks distinct marker beds. Provenance analysis from detrital zircon geochronology provides one strategy for overcoming these challenges. Previous U-Pb geochronology indicates the lower succession was deposited <2.32 Ga, and the upper succession was deposited between <2.17 Ga and >1.94 Ga. We provide new U-Pb detrital zircon ages for the upper succession, including a new maximum depositional age at <2.00 Ga. We integrate our new data with published detrital zircon ages and compare them with published and public-domain igneous crystallization ages stored within a large geochronological database to identify potential provenance locations. While there is no known local source for the ca. 2.17 Ga age population, potential 2.17 Ga sources are found on the neighboring Slave craton and Buffalo Head–Chinchaga domain. Geographically, sources for the remaining dominant age populations (e.g., 2.33 Ga) exist either locally, or between the potential sources for ca. 2.17 Ga zircon grains and our study area. Our results support the interpretation that the Rae and Slave cratons were already amalgamated during upper Murmac Bay Group deposition (<2.00 to >1.94 Ga). This provides an important constraint on the timing of Rae-Slave amalgamation.

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INTRODUCTION in the early stages of the Trans-Hudson orogeny setting in the hinterland of a convergent plate (ca. 1.92–1.80 Ga; Corrigan et al., 2009). margin (Chacko et al., 2000; De et al., 2000), The southwestern Rae craton of the Cana- The southwestern Rae craton is bounded to requiring that the Slave and Rae cratons would dian Shield (Fig. 1) is separated from the Hearne the west by the ca. 2.00–1.90 Ga Taltson mag- have already been assembled by 2.00 Ga. craton to the east by a geophysical boundary matic zone, which has been interpreted as the Hence, there exists considerable debate as known as the Snowbird tectonic zone (Hoffman, southern extension of the approximately coeval to the timing of amalgamation of the Rae and 1988); together, the Rae and Hearne cratons Thelon orogeny (Hoffman, 1988), and more its neighboring cratons. Given the uncertainty constitute the western Churchill Province. The recently as a separate entity (Card et al., 2014, regarding the interpretation of the late Archean Snowbird tectonic zone has been variously inter- 2010) resulting from either the amalgamation of to early Paleoproterozoic tectonic evolution of preted as a late Archean (2.6 Ga) intracratonic the Slave and Rae cratons, or accretion of the the Rae, Hearne, and Slave cratons, including shear zone (Hanmer et al., 1995a, 1995b) or an Buffalo Head terrane to an already sutured Slave their configuration and nearest cratonic neigh- Archean suture (Regan et al., 2014) prior to the and Rae structure (Card et al., 2014). Card et al. bors during this time, these regions require fur- ca. 2.10 Ga breakup of a long-standing super- (2014) reinforce the idea that the Taltson mag- ther study to fully understand the origin of the continent, Kenorland (Aspler and Chiarenzelli, matic zone is a 1.99–1.96 Ga subduction-related Snowbird tectonic zone and Taltson-Thelon 1998). Alternatively, it has been hypothesized magmatic arc emplaced into older rocks of the orogenies (e.g., Pehrsson et al., 2013). to represent a Paleoproterozoic (1.92–1.90 Ga) Taltson basement complex (e.g., McDonough et The relative paleogeographic positions of suture (Berman et al., 2007), possibly formed al., 2000) and that this arc (and related basement cratons and cratonic blocks during the earliest substrate) extends into Saskatchewan south of Paleoproterozoic Era (prior to the Trans-Hudson Camille A. Partin http://​orcid​.org​/0000​-0002​ the Athabasca Basin. An alternative interpreta- orogen) are difficult to constrain, owing, at least -1544-7994 tion suggests emplacement in an intracontinental in part, to a paucity of reliable paleomagnetic

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Figure 1. Currently exposed generalized geology of southern Rae and surrounding cratons in the Canadian Shield after Ashton et al. (2013). BBF—Black Bay fault, GRSZ—Grease River shear zone; black rectangle highlights study area. Canadian provinces are labeled in gray as follows: NWT—Northwest Territories, NU—Nunavut, AB—Alberta, SK—Saskatchewan, MB—Manitoba.

data. However, provenance studies of Protero- database also contains more than 35,000 indi- combining geochronology with other available zoic sedimentary basins provide an opportunity vidual detrital zircon analyses. We present new tools, such as radiogenic and tracer isotopic anal- to constrain the position of surrounding cratons, if U-Pb detrital zircon data from the Murmac Bay ysis, geochemical data, and stratigraphy, have unique sediment sources can be identified. Post- Group on the Rae craton and integrate this data been effectively applied in determining sedimen- depositional deformation and metamorphism of set with available published U-Pb detrital zircon tary provenance, correlating sedimentary basins, these sedimentary basins can obscure primary ages and compare the dominant age populations and inferring tectonic setting (e.g., Tran et al., sedimentary structures, presenting an additional with crystallization ages recorded in DateView to 2008; Rainbird et al., 2010; Bethune et al., 2010, challenge, though provenance studies integrating discover potential sediment sources. Provenance 2013; Ashton et al., 2013; Partin et al., 2014; geochronology and isotopic analysis of detrital analysis using detrital zircon geochronology Wodicka et al., 2014). In particular, Rainbird et zircon, stratigraphy, geochemistry, and structural can provide important insight into surrounding al. (2010) present a compilation of stratigraphy and metamorphic data have been successful in source terranes, and thus can be used to constrain and detrital zircon U-Pb geochronology, compar- identifying sediment provenance (e.g., Gehrels the tectonic setting of sedimentary basins. This ing Paleoproterozoic sedimentary successions on et al., 1990; Thomas et al., 2004; Weislogel et al., technique presents an opportunity, in particular, the Rae craton with the broadly coeval Hurwitz 2006; Horton et al., 2008; Collo et al., 2009). This to study polydeformed or higher-metamorphic- Group on the Hearne craton. The detrital zir- approach requires robust data sets containing iso- grade sedimentary successions, since zircon is con age spectra from these sedimentary succes- topic data from detrital zircon—common in silici- highly refractory and resistant to isotopic reset- sions reveal an important change in provenance clastic sedimentary rocks—as well as a robust ting (Corfu et al., 2003; Finch and Hanchar, 2003; in the upper stratigraphy, suggesting that the ca. database of U-Pb crustal ages from a diverse suite Hoskin and Schaltegger, 2003). 1.92–1.90 Ga units are correlative across the Rae- of cratons with which to compare detrital zircon Recent detrital zircon U-Pb geochronologi- Hearne boundary, marking the oldest definitive age spectra. We approach this provenance study cal data sets from Paleoproterozoic sedimen- trans-Churchill overlap succession (Rainbird et by utilizing the DateView database, which con- tary successions on the Rae and Hearne cratons al., 2010). Previous tectonic models interpreted sists of a global compilation of over 27,000 U-Pb have highlighted important similarities and the relative positions of the Rae and Hearne zircon crystallization and metamorphic ages. The differences in their provenance. Approaches cratons prior to the Trans-Hudson orogeny (ca.

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1.90 Ga) differently (Hoffman, 1988; Hanmer et Slave, or other nearby cratons could have pro- broadly consists of a lower and upper succession al., 1995a, 1995b; Berman et al., 2007; Corrigan vided sediment to the Murmac Bay paleobasin, unconformably deposited on Mesoarchean gra- et al., 2009; Regan et al., 2014), highlighting thereby providing a constraint as to their relative nitic basement. Previous mapping efforts (e.g., the need for robust and extensive data sets of cratonic configuration in the early Paleoprotero- Hartlaub et al., 2004; Ashton et al., 2007, 2013) geochronological and isotopic data to facilitate zoic Era, prior to the formation of Laurentia have provided a tectonostratigraphic framework, rigorous provenance and paleotectonic analysis. (Hoffman, 1988). summarized next. Our study focuses on the Paleoproterozoic Murmac Bay Group, situated in the Beaverlodge GEOLOGICAL SETTING Lower Murmac Bay Group domain of the southwestern Rae craton in north- ern Saskatchewan, Canada (Fig. 2). The Murmac The Murmac Bay Group is a key compo- In the vicinity of Uranium City, the lower Bay Group is ideally located for provenance and nent of the Beaverlodge domain, one of several Murmac Bay Group was deposited unconform- paleotectonic analysis because it is adjacent to lithotectonic domains within the exposed por- ably on the Mesoarchean granitic basement, rep- the Taltson orogeny at the Rae-Slave boundary tion of the southern Rae craton in the Athabasca resented by ca. 3.06–2.99 Ga granites (Persons, as well as to the Snowbird tectonic zone at the region of Saskatchewan, Canada. The Beaver- 1988; Hartlaub et al., 2004). The North Shore boundary between the Rae and Hearne cratons. lodge domain is bounded by the Black Bay fault plutons, a ca. 2.33–2.29 Ga felsic plutonic suite, We expand on traditional approaches to deter- to the west, the Grease River shear zone to the intrude the granitic basement and also underlie mining provenance by making use of a large east (Fig. 1), and the Oldman-Bulyea shear zone the lower Murmac Bay Group along the Crack- database of geochronological data to include to the north. The best exposure of the Murmac ingstone Peninsula (Fig. 2). These plutons have candidates from more distal sources, including Bay Group is its type locality in the vicinity been interpreted to be a product of syn- to post- neighboring cratons. We determined the prov- of Uranium City, Saskatchewan (Fig. 2), where collisional extension following the ca. 2.50–2.30 enance of the Murmac Bay Group by compar- the metamorphic grade is lowest (greenschist Ga Arrowsmith orogeny (Hartlaub et al., 2007; ing the U-Pb age of crustal rocks from the Rae to lower amphibolite facies). Thus, the Mur- Ashton et al., 2009, 2013). In the Elliot Bay and neighboring cratons stored in the DateView mac Bay Group around Uranium City is the region (Fig. 2), the granitic basement is locally database (Eglington et al., 2013). Using these primary focus of this study. The <2.33 to >1.94 overlain by the basal polymictic conglomer- data, we test the hypothesis that the Hearne, Ga Murmac Bay Group (Ashton et al., 2013) ate of the Murmac Bay Group, which, where

Figure 2. Sample locations in the Murmac Bay Group and simplified geology of the Uranium City, Saskatchewan area, after Ashton et al. (2013). Lithologic domains are labeled in gray. Diamonds are ages from previously published data (Hartlaub et al., 2006; Ashton et al., 2013), stars denote new samples collected for this study, and circles indicate metamorphic ages as indicated by monazite growth (Bethune et al., 2013).

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present, grades into a mature gray quartzite that (Hartlaub et al., 2004). The lack of preserved Murmac Bay Group, pointing to an early Paleo- represents the basal unit for most of the Mur- sedimentary structures makes it difficult to proterozoic maximum depositional age, rather mac Bay Group (Fig. 3; Hartlaub et al., 2004; determine the cause of this interlayering, which than Archean (Hartlaub et al., 2006, 2007). Ashton et al., 2013). The quartzite is intercalated could be a result of deformation. It has been Further mapping and analytical work reeval- with metamorphosed psammite, oligomictic suggested that an intraformational unconformity uated previously reported intrusive relationships conglomerate, and dolostone, which is, in turn, exists, which separates the upper and lower units between plutons and the Murmac Bay Group; interlayered with silicate and oxide facies iron of the Murmac Bay Group (Ashton et al., 2013; for instance, the migmatitic pelite intruded by formation toward the top of the unit (Hartlaub et Bethune et al., 2013). the Dead Man granite has been reinterpreted al., 2004). Mafic volcanic rocks sit stratigraphi- to be part of a structurally deeper basement cally above the basal quartzite (Hartlaub et al., Metamorphism and Deformation complex distinct from the Murmac Bay Group, 2004; Ashton et al., 2013), representing the top based on ca. 2.34 Ga metamorphic monazite of the lower Murmac Bay Group (Fig. 3). The The Murmac Bay Group has experienced at (Ashton et al., 2013; Bethune et al., 2013). Sev- lower Murmac Bay Group, and possibly the low- least two episodes of metamorphism, as indi- eral samples included in previous studies from ermost upper Murmac Bay Group, are intruded cated by monazite growth in deformation fabrics the Murmac Bay Group and the Donaldson Lake by ultramafic rocks and coarse-grained gabbro at ca. 1.93 Ga (Fig. 2) and at ca. 1.91 Ga (Bet- pluton (Hartlaub et al., 2004) were subsequently dikes and sills, the age of which has not been hune et al., 2013). The earliest metamorphism reanalyzed using laser ablation–inductively determined, but which have been interpreted as is attributed to the terminal collision of the Rae coupled plasma–mass spectrometry (LA-ICP- feeder dikes to Murmac Bay Group volcanism and Slave cratons, or alternatively, the collision MS) techniques to obtain a more robust data (Hartlaub et al., 2004). between the already amalgamated Slave and Rae set along with newly collected samples from cratons with the Buffalo Head terrane during the the lower Murmac Bay Group and one from Upper Murmac Bay Group ca. 1.99–1.93 Ga Thelon and Taltson orogenic the upper Murmac Bay Group, and an intru- events (Hoffman, 1988; Card et al., 2010, 2014). sive quartz-feldspar porphyry dike (Hartlaub et The upper Murmac Bay Group is composed The younger ca. 1.91 Ga metamorphism is attrib- al., 2006; Ashton et al., 2013). The Donaldson of laterally extensive quartzofeldspathic pelitic uted to the development of the Snowbird tectonic Lake granite intrudes the entire Murmac Bay to psammopelitic rocks that are locally migma- zone during the Snowbird orogeny (Berman et Group, and analysis of zircon from this unit titic at higher metamorphic grades. At the base al., 2007; Bethune et al., 2013). originally yielded a poorly constrained crystal- of the upper Murmac Bay Group, the pelitic Metamorphic grade in the Murmac Bay lization age of 2634 ± 55 Ma (TIMS) from four to psammopelitic rocks are locally interlayered Group is lowest (greenschist facies) just east of of five moderately discordant (5%–7%) analyses with lower Murmac Bay Group volcanic rocks the Black Bay fault, which marks the boundary (Hartlaub et al., 2004). Based on composition, between the Beaverlodge domain and the Zemlak style of emplacement, and reanalysis, Ashton domain to the west (Fig. 2), increasing eastward et al. (2013) reinterpreted this unit as a crustal in grade to upper amphibolite and local granulite melt derived from regional metamorphism con- facies in the central Beaverlodge domain (Hart- taining abundant inherited grains, with a U-Pb laub et al., 2007; Ashton et al., 2009; Bethune crystallization age of 1930 ± 19 Ma (LA-ICP- et al., 2013). The Black Bay fault is a long-lived MS) based on two of three concordant analyses discontinuity interpreted to have experienced out of 12 total in this age range. Considering the normal displacement, causing the eastern block constraints provided by metamorphic monazite to be downthrown (Ashton et al., 2009) prior to (above) and the new age of the crosscutting Don- ca. 1.90 Ga (Bethune et al., 2013). Rocks of the aldson Lake granite, the deposition of the upper upthrown west block are of higher metamorphic Murmac Bay Group must have ceased by ca. grade, some intensely ductilely deformed (Hart- 1.93 Ga, thereby providing a minimum age con- laub et al., 2004). Immediately west of the Black straint for the Murmac Bay Group. Conglomer- Bay fault, exposed upper-amphibolite-facies ates and arkoses of the ca. 1.82 Ga Martin Group paragneisses have been interpreted as belonging unconformably overlie the Murmac Bay Group to the Murmac Bay Group based on lithological over much of the Beaverlodge domain (Hartlaub association (Ashton et al., 2013). et al., 2004; Morelli et al., 2009). A Paleoproterozoic maximum depositional Age and Tectonic Setting of the Murmac age for the lower Murmac Bay Group was cor- Bay Group: Previous Work roborated by a youngest detrital zircon (YDZ) of 2323 ± 2.3 Ma in the basal conglomerate The Murmac Bay Group was originally inter- unit (Ashton et al., 2013). The quartzite unit preted to be Archean (ca. 2.70 Ga) based on detrital zircon ages range from 3.95 to 3.40 Ga thermal ionization mass spectrometry (TIMS) (Hartlaub et al., 2006), and detrital zircon grains Figure 3. Simplified tectonostratigraphy of the U-Pb geochronology of detrital zircon from two from a metamorphosed psammite from within Murmac Bay Group modified from Ashton et al. samples of lower Murmac Bay Group rocks and the quartzite unit range in age from 3.8 to 2.3 Ga, (2013) showing relative stratigraphic positions two granites (ca. 2.60 Ga Donaldson Lake and with the weighted mean of the four YDZ ages of samples. Stratigraphic order in the upper Dead Man) interpreted to intrude the lower Mur- at 2329 ± 8.6 Ma (Fig. 4; Ashton et al., 2013). Murmac Bay Group (U1 through U4) is inferred, because primary sedimentary structures have mac Bay Group (Hartlaub et al., 2004). Further A psammopelitic gneiss associated with been largely erased by multiple episodes of study in this region resulted in the discovery of minor quartzite from the southeastern Beaver- deformation in the upper succession. ca. 2.30 Ga volcaniclastic rocks in the lower lodge domain, near Fond-du-Lac, Saskatchewan,

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Figure 4. U-Pb age data for the Murmac Bay Group compiled and plotted using FitPDF. Probability curves are shown in light gray, and histograms are outlined in black, where bin width is 15 m.y. Probability is normalized to 100%. YDZ—youngest detrital zircon. Techniques: SHRIMP—sensitive high-resolution ion microprobe; LA-ICP-MS—laser-ablation–inductively coupled plasma–mass spectrometry; ID-TIMS—isotope dilution–thermal ionization mass spectrometry.

yielded a YDZ age of 2030 ± 16 Ma (Ashton et detrital zircon populations in the lower Mur- are no paleocurrent data to guide our provenance al., 2007; Knox, 2011), which is thought to rep- mac Bay Group, the abundance of 3.95–3.40 Ga study. resent the upper part of the Murmac Bay Group detrital zircon in the basal quartzite suggests a The basin tectonic setting of the Murmac Bay (Knox et al., 2008). Its stratigraphic position distal source, since no source rocks of this age Group during the early and late stages of forma- relative to the upper Murmac Bay Group in the are known proximally (Ashton et al., 2013). Iso- tion is still poorly defined, but it could represent Uranium City area is difficult to determine, due lated dolostone layers near the top of the lower a rift (lower Murmac Bay Group) to passive- to access limitations between these localities. Murmac Bay Group suggest a shallow-marine margin succession (upper Murmac Bay Group), The YDZ reported from the upper Murmac Bay depositional environment during this time (Hart- an intracratonic basin for the entire Murmac Bay Group pelite sample in the vicinity of Mackin- laub et al., 2004; Ashton et al., 2013). Recent Group, a foreland basin setting (upper Murmac tosh Bay was 2171 ± 31 Ma (Fig. 4), which has discovery of 13C-enriched carbon isotope val- Bay Group; Hartlaub et al., 2004; Bethune et al., been considered to be the maximum depositional ues suggests that deposition of the dolostone 2013; Ashton et al., 2013), or a combination of age constraint for the upper succession (Ashton occurred sometime during the ca. 2.20–2.06 Ga these. Interbedding of the basal conglomerates et al., 2013; Bethune et al., 2013). The paucity of Lomagundi event (McDonald and Partin, 2016), and quartzites may be due to episodic faulting Archean grains in the upper Murmac Bay Group which agrees with the detrital zircon U-Pb age consistent with an extensional tectonic setting sample suggests a shift in sediment source for constraints described already. (Ashton et al., 2013), possibly in a rift or an the upper pelitic to psammopelitic succession, Primary sedimentary structures are preserved intracratonic basin setting for the lower Murmac as previously suggested by Ashton et al. (2013). only locally in the quartzite unit of the lower Bay Group (Hartlaub et al., 2004; Bethune et al., Deposition of the lower Murmac Bay Group Murmac Bay Group, consisting of planar and 2013). The rift basin interpretation is also sup- is inferred to have occurred shortly after the trough cross-bedding, ripple marks, and scour ported by the presence of basal conglomerates emplacement of the North Shore plutons, based channels, all of which are moderately deformed and mafic volcanic rocks in the lower Murmac on similar ages of these plutons and the YDZ (Hartlaub et al., 2004), while the upper Murmac Bay Group, which suggest extension (Hartlaub in the lower Murmac Bay Group, following ca. Bay Group lacks sedimentary structures alto- et al., 2004). Evidence for the foreland interpre- 2.30 Ga metamorphism of the basement rocks gether, making the determination of stratigraphic tation includes metamorphism coincident with during the Arrowsmith orogeny (Bethune et al., relationships, thickness estimates, paleocurrent the Taltson orogen (Bethune et al., 2013). Thus, 2013). While local sources (e.g., North Shore measurements, and depositional paleoenviron- the upper Murmac Bay Group could have been plutons) exist for the dominant ca. 2.33 Ga ment difficult (Hartlaub et al., 2004). Thus, there deposited in a passive-margin, intracratonic, or

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foreland basin setting according to previous To decrease bias, grains were picked to Imaging guided selection of the target areas for hypotheses. Here, we test the foreland basin include a representative sample with respect to analyses, dominantly within the centers of the hypothesis for the upper Murmac Bay Group grain size, color, and morphology. Zircon grains grains, unless otherwise noted in Table DR1. using provenance data. If the sediment sources were mounted at the Canadian Centre for Isoto- Grains were targeted to avoid fractures and can be confidently attributed to either the Slave pic Microanalysis, University of Alberta, in a 25 inclusions, where possible. In order to obtain craton or Buffalo Head–Chinchaga domain, this mm epoxy mount along with zircon standards the igneous crystallization age of zircon grains, provides evidence in favor of deposition of the (Temora2 and MudTank) for U-Pb calibration, target spots were chosen in the interior of grains upper Murmac Bay Group in the foreland of and polished using diamond grits to expose the where igneous growth zoning could be identi- the Taltson orogen, and collision of the respec- midsections of the crystals. In order to charac- fied in BSE and CL images. Most grains in this tive craton. terize internal zircon structures (e.g., zoning) study exhibited this characteristic growth zoning and alteration, imaging was carried out using in their centers, and care was taken to avoid any METHODS a Zeiss EVO MA15 scanning electron micro- areas of grains where this growth-zoning pattern scope equipped with a high-sensitivity, broad- appeared mottled, recrystallized, or otherwise The upper Murmac Bay Group is dominantly band cathodoluminescence (CL) detector and altered. Full U-Pb analysis results are included composed of finer-grained lithologies (pelites to a backscattered electron (BSE) detector. These in Table DR1. psammopelites) compared to the lower succes- images revealed that most zircon grains in this The crystallization age data used for compar- sion, making mineral separation and subsequent study exhibited zoning in the centers of the ison in this study were compiled from relevant analysis of small zircon grains from these lithol- grains characteristic of igneous growth, as well literature into the DateView (Eglington, 2004) ogies challenging. In order to further constrain as numerous fractures and common inclusions. and StratDB databases (Eglington et al., 2013). the depositional age and to investigate the prov- The majority of grains also had unzoned over- DateView contains more than 100,000 published enance of the upper Murmac Bay Group, detrital growth rims that appeared dark under CL imag- and public-domain isotope geochemical records, zircon grains were handpicked from the three ing, while several grains also showed signs of which are tied to lithostratigraphy, metamor- samples collected for this study, a pelite from the recrystallization, some zoned and some unzoned phism, tectonism, ore deposits, large igne- type section of the upper Murmac Bay Group (see Fig. DR1 in the Data Repository item1 for ous provinces, and full references in StratDB near Uranium City, and two psammopelitic sam- zircon images). (Eglington et al., 2013). We added records for ples from upper-amphibolite-grade rocks just U and Pb isotope ratios were determined published zircon U-Pb geochronology on the west of the Black Bay fault (sample locations at the Geological Survey of Canada in Ottawa Murmac Bay Group (Table 1), as well as igne-

are shown in Figure 2 and Table 1) interpreted using an O2-primary beam on the sensitive high- ous and metasedimentary rocks on the southern to belong to the upper Murmac Bay Group. New resolution ion microprobe (SHRIMP) follow- Rae and proximal cratons from zircon, including samples from the upper Murmac Bay Group in ing the procedures of Stern (1997) (Table DR1). U-Pb geochronological data obtained by TIMS,

this study are: 14KA-095 (U1), 14KA-098 (U2), LA-ICP-MS, and SHRIMP methods (Hartlaub and 14CAP0911-5 (U3). For simplicity, our new 1 GSA Data Repository Item 2016268, Figure DR1 et al., 2004, 2006; Tran et al., 2008; Rainbird et results and results from previously published (backscattered electron and cathodoluminescence al., 2010; Ashton et al., 2013; Mumford, 2013), detrital zircon data are referred to according to images of select detrital zircon grains), Figure DR2 to provide a comprehensive data set from which relative stratigraphic order (Figs. 3 and 4), with (plot of grain age vs. depositional age annotated with to explore potential provenance locations. samples from the lower Murmac Bay Group (L , Th/U ratios), Figure DR3 (rock sample photos), and Probability density function curves and his- 1 Table DR1 (detrital zircon U-Pb geochronological re- L2, L3) below those from the upper Murmac Bay sults), is available at www.geosociety.org/pubs​ /ft2016​ ​ tograms were calculated using FitPDF software

Group (U1, U2, U3, U4). .htm, or on request from [email protected]. (Eglington, 2013), screening data for ±10%

TABLE 1. DETRITAL ZIRCON GEOCHRONOLOGY DATA FOR THE MURMAC BAY GROUP Sample locations Field sample Age range Primary age Secondary age YDZ§ Sample ID Rock type Technique# Reference ID Latitude Longitude (Ga) peak (Ga) peaks (Ga) (Ga) (°N) (°W) U4 4707-0210 Pelite 59.4841 108.2695 3.14–1.90 2.17 2.60, 2.13 2.17 SHRIMP Ashton et al. (2013) U3 14CAP0911-5Metapelite 59.5634 108.5276 3.05–1.99 2.17 2.33, 2.10 1.99 SHRIMP This paper U2 14KA-098 Psammopelitic 59.5132 108.7520 2.41–1.85 2.33 2.09 2.00 SHRIMP This paper gneiss U1 14KA-095 Psammopelitic 59.5044 108.7695 2.54–1.91 2.33 2.12, 2.08, 1.94 2.01 SHRIMP This paper gneiss L3 RH98-46 Psammopelitic 59.4668 108.2929 3.80–2.33 3.60 3.05, 2.72, 2.33 2.33 LA-ICP-MS Ashton et al. (2013) gneiss L2 4700-6106 Quartzite 59.5561 108.4400 3.95–3.41 3.75 3.86, 3.71 3.41 LA-ICP-MS Hartlaub et al. (2006) L1 4701-0765 Conglomerate 59.3876 108.7233 2.33 2.33 N.A.† 2.32 TIMS Ashton et al. (2013) Note: In our study, we assessed the youngest detrital zircon (YDZ) to reflect the zircon grains with the youngest age that did not show textural evidence of alteration. Younger ages were obtained in our analysis, but they do not provide a robust indication of maximum depositional age. The YDZ from literature data is cited from the source. Full U-Pb data for samples collected for this study are provided in Table DR1 (Data Repository). *Sample locations provided in WGS84. †N.A.—not applicable. §YDZ—youngest detrital zircon. #Techniques: SHRIMP—sensitive high-resolution ion microprobe; LA-ICP-MS—laser-ablation–inductively coupled plasma–mass spectrometry; TIMS—thermal ionization mass spectrometry.

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discordance; maximum probabilities were nor- RESULTS gray-brown, quartzofeldspathic, psammopelitic malized to 100% for ease in comparison of data gneiss with anastomosing penetrative foliation. sets (Fig. 4). Primary and secondary age modes Sample Descriptions It contains 30–40% quartz (up to 1 cm), ~25% were identified qualitatively from peaks in the feldspar (up to 1.5 cm), 15–20% biotite, ~10%

probability density function, and a list of poten- Sample 14KA-095 (U1) muscovite, ~10% chlorite after biotite, and tial source candidates with isotopic ages match- The two samples collected just west of the minor titanite, zircon, and sulfides. Sixty-seven

ing these peaks was compiled using StratDB. Black Bay fault for this study (14KA-095, U1 analyses were performed on a total of 65 grains

These potential candidates were also filtered to and 14KA-098, U2) are upper-amphibolite- from this sample. Detrital zircon grains in this include only those records with ±10% discor- facies paragneisses attributed to the upper Mur- sample are euhedral to subhedral, and cloudy dance, and which were interpreted to be either mac Bay Group based on their lithological asso- to translucent brown, with an average length of igneous crystallization or inherited ages in their ciation (quartzite-mafic volcanic-psammopelitic 190 mm and an average length-to-width ratio of publication. In total, 2556 records matched these gneiss; Ashton et al., 2013). Since these samples 1.9. Grain morphology ranges from rounded to criteria within Canada, the ages of which were were obtained from the upthrown west block of equant to elongate, and most nonrounded grains spatially referenced using ArcMap to determine the Black Bay fault, they are likely from a lower are doubly terminated. Analyses were targeted their geographic relationships to the source stratigraphic level than the sample collected east to avoid fractures and inclusions present in

locations (Figs. 5–7). Provenance candidates of the fault (14CAP0911-5, U3), though pre- most grains. The centers of these grains typi- matching the most dominant detrital zircon age cise stratigraphic relationships are difficult to cally (88%) showed oscillatory growth zoning, populations were then further investigated to determine in the upper succession due a lack though in about half of the grains, this zoning determine their suitability as sources for upper of preserved sedimentary structures. Sample was altered or convoluted. One zircon grain

Murmac Bay Group sediments. 14KA-095 (U1) is an upper-amphibolite-facies, analyzed had a featureless interior in images.

Figure 5. Potential provenance locations for Murmac Bay Group detrital zircon age peaks within Canada derived from the DateView database. Candidate source locations on proximal cratons are shown in color, and distal cratons are in gray scale. Canadian provinces are labeled in gray as follows: NWT—Northwest Territories, NU—Nunavut, AB—Alberta, SK—Saskatchewan, MB—Manitoba, BC—British Columbia, YT—Yukon, ON—Ontario, QC—Quebec, NB—New Brunswick, PE—Prince Edward Island, NS—Nova Scotia, NL—Newfoundland.

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Figure 6. Potential provenance locations for Murmac Bay Group detrital zircon age peaks of Paleoproterozoic age derived from the DateView database. Inset box shows approximate location of map in Figure 7. Canadian provinces are labeled in gray as follows: NWT—Northwest Territories, NU—Nunavut, AB—Alberta, SK—Saskatchewan, MB—Manitoba, BC—British Columbia, YT—Yukon, ON—Ontario, QC—Que- bec, NB—New Brunswick, PE—Prince Edward Island, NS—Nova Scotia, NL—Newfoundland.

Dark CL overgrowths were present in all zir- discordance, Th/U = 0.52) and thus is inter- feldspar, ~20% biotite, and ~10% muscovite, con grains in this sample, averaging 35 mm in preted as the YDZ in this sample. This grain is with minor cordierite, garnet, sillimanite, apatite, thickness (Fig. DR1). Two analysis spots were prismatic in shape with a metamorphic over- and zircon. In total, 64 analyses were performed targeted in metamorphic domains where they growth around the rim too narrow for analysis; on 60 detrital zircon grains taken from sample

were large enough to accommodate the spot thus, the analysis was targeted in the interior of 14KA-098 (U2). Grains in this sample are mainly size: one on an overgrowth rim that was dark the grain in an igneous domain exhibiting both transparent to cloudy to translucent brown, with in CL images (s3177–067.2), and one on an sector and igneous growth zoning. Only two an average length of 170 mm, and an average interpreted recrystallized zone that embayed a grains in this sample yielded ages ≥2.50 Ga (Fig. length-to-width ratio of 1.6; grain morphology

zone exhibiting igneous growth zoning (s3177– 4). The analyses collected from metamorphic is also similar to that seen in sample U1. Most 071.1). The Th/U ratio ranges from 0.004 to overgrowth of two grains yielded 207Pb/206Pb grains (79%) showed oscillatory growth zoning 1.05, and all grains in this sample with Th/U ≤ ages of 1917 ± 15 Ma (s3177–067.2) and 1931 at their centers; two-thirds of the grains showed 0.47 exhibit evidence of alteration of original ± 11 Ma (s3177–071.1) and Th/U values of 0.06 evidence of alteration fronts extending into their igneous growth zoning (e.g., mottling) in CL and 0.01, respectively, corresponding to the tim- centers. All zircon grains in this sample also 207 206 images. The Pb/ Pb ages in sample U1 range ing of known metamorphic events in this region showed overgrowth rims that appeared dark from 2.54 to 1.91 Ga. The largest population (Bethune et al., 2013). under CL, with an average thickness of 32 mm (n = 17) of zircon ages is centered on 2.31 Ga, (Fig. DR1). One grain in this sample had a meta-

with minor populations at 2.12 Ga (n = 13), 2.08 Sample 14KA-098 (U2) morphic zone that was thick enough to accom- Ga (n = 10), and 1.93 Ga (n = 9; Fig. 4). The This sample, from the west of the Black Bay modate the U-Pb spot, which was thus targeted youngest grain that does not exhibit evidence fault (Fig. 2), is similar in appearance and char- for analysis, in a featureless, recrystallized outer

of alteration of igneous zoning in images in this acter to sample 14KA-095 (U1), but it is coarser rim (S3178–068.1). The Th/U ratio in this sam- sample is 2005 ± 18 Ma (S3177–001.1, 4.8% grained. It consists of ~40% quartz, ~20% ple ranged from 0.17 to 0.89, and all grains with

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Figure 7. Close-up view of study area showing potential prove- nance locations proximal to study area. Candidate sources for the dominant ca. 2.17 Ga detrital zir- con age population are annotated with their interpreted crystalliza- tion ages. Reference data for these ages appears in Table 2. Potential source for ca. 2.14 Ga age popu- lation is annotated in the Taltson basement complex (McNicoll et al., 2000). BH-C—Buffalo Head– Chinchaga domain. Canadian provinces are labeled in gray as fol- lows: NWT—Northwest Territories, NU—Nunavut, AB—Alberta, MB— Manitoba, SK—Saskatchewan.

Th/U ≤0.40 showed evidence of alteration of the is very fine-grained with planar foliation, ~50% (with a smaller error) is 2014 ± 11 Ma. The igneous growth zoning in CL images. The range micas (biotite and chlorite), 20%–25% quartz, probability density plot shows that most of the of 207Pb/206Pb ages in this sample is from 2.41 and ~5% rutile and feldspar, with minor chlorite, analyzed grains have Paleoproterozoic crystal- to 1.85 Ga, with the dominant population (n = quartz, and carbonate occurring as either veins lization ages, whereas only five grains exhibit 25) of detrital zircon ages centered around 2.31 or along cleavage planes. This sample did not Archean crystallization ages (Fig. 4). Ga. Secondary populations can be seen at 2.26 yield abundant detrital zircon grains; in total, 40 Ga (n = 7), 2.17 Ga (n = 6), and 2.07 Ga (n = 9), grains were selected for U-Pb analysis. The zir- Detrital Zircon Age Probability Density and there are no Archean zircon grains in this con grains in this sample are cloudy to medium Plots and Histograms sample (Fig. 4). The YDZ that does not show translucent brown, with an average length of 85 any evidence of alteration of igneous zoning or mm, and average length-to-width aspect ratio of Zircon U-Pb age data are displayed in prob- recrystallization in this sample is dated at 2056 1.5. The zircon grains in this sample are mostly ability density plots and histograms keyed to ± 14 Ma (S3178–121.1), a prismatic grain that equant to rounded, and several of these grains stratigraphic position, where known, in Figure 4. shows evidence of alteration around the rim, but are broken fragments. Analysis spots were cho- Ashton et al. (2013) reported the age of the YDZ was targeted for analysis in an interior domain sen to avoid fractures within the grains, most grain in the lower succession as 2329 ± 8.6 Ma,

that showed characteristic igneous growth zon- (90%) of which exhibited oscillatory growth from the psammopelitic gneiss (L3) sample near ing in BSE and CL images. The analysis per- zoning, though a few grains were clear and fea- the stratigraphic top of the lower Murmac Bay formed on the recrystallized rim yielded an age tureless. The majority (75%) of grains in this Group; this, together with zircon analyses from

of 1999 ± 9 Ma (S3178–068.1), with Th/U of sample also had thin (≤15 mm) overgrowth rims, the basal conglomerate (L1) defining a single 0.20 (Fig. 4). Because the age of this metamor- which were dark in CL images (Fig. DR1). The peak ca. 2.30 Ga, establishes a maximum depo- phic rim is older than the interpreted crystalliza- Th/U ratio ranged from 0.07 to 1.01, with the sitional age for the lower Murmac Bay Group ca.

tion age of the Donaldson Lake pluton, which lowest values (≤0.36) occurring on grains that 2.30 Ga, while the quartzite (L2) contains only intrudes the Murmac Bay Group (ca. 1.93 Ga; exhibited evidence of alteration in CL images. Archean (>3412 ± 11 Ma) grains (Hartlaub et 207 206 Ashton et al., 2013), this metamorphism may The Pb/ Pb ages for this sample range from al., 2006). The psammopelitic gneiss (L3) also have occurred prior to transportation and depo- 3.05 to 1.99 Ga. Most analyses plot between contains zircon grains with both late Archean sition of this grain, making this the youngest 2.33 and 2.00 Ga, with the highest population and early Paleoproterozoic ages, implying that

detrital age from sample U2. (n = 7) plotting at 2.17 Ga and secondary popu- the sediments comprising L3 had a more diverse lations at 2.33 Ga (n = 5) and 2.10 Ga (n = 4; provenance than that of the quartzite (Ashton et

Sample 14CAP0911–5 (U3) Fig. 4). The YDZ in sample U3 is 1989 ± 29 Ma al., 2013). Both L2 and L3 have dominant zircon A greenschist-facies pelitic schist was col- (S3179–046.1, -2% discordance, Th/U = 0.48), populations with ages between 3.90 and 3.60

lected from the upper Murmac Bay Group in the for a small broken grain with apparent igneous Ga. Overall, the lower Murmac Bay Group (L1,

vicinity of Uranium City (Fig. 2). This sample growth zoning (Fig. 4). The next youngest grain L2, L3) contains a greater abundance of Archean

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grains than samples from the upper Murmac was wide enough to accommodate the beam size Identifying Potential Sources Bay Group. and was targeted for analysis to investigate the In contrast, the upper Murmac Bay Group timing of this overgrowth, yielding an age of Provenance candidates were determined by samples exhibit a paucity of Archean zircon 1917 ± 15 Ma (Th/U = 0.06). Another analysis matching dominant age peaks in the Murmac grains, reinforcing the idea of a shift in sedi- targeted in an area that appeared to be recrys- Bay Group detrital zircon spectra to published ment source between deposition of the lower tallized, where zircon of a different texture was igneous crystallization ages stored within the and upper Murmac Bay Group. The samples “embayed” into the regular growth-zoned tex- DateView database (Eglington, 2004; Eglington

(U3 and U4) collected east of the Black Bay fault ture, was used to further investigate the timing et al., 2013). The least common crystallization (Fig. 2) contain minor amounts of Neoarchean of metamorphism, which yielded an age of 1931 ages from the database that matched detrital zir-

grains, the latter (U4; Ashton et al., 2013) with ± 11 Ma (Th/U = 0.01). These correspond to con age peaks in our data were identified and a secondary peak near 2.60 Ga. In both of these the previously reported ages of metamorphic investigated further as potentially unique sedi- samples, the dominant population is ca. 2.17 Ga. monazite growth in the Murmac Bay Group ment sources. This approach does present limi-

The two gneissic samples (U1 and U2) collected (Bethune et al., 2013). Considering that most tations in that only published isotope data were for this study from the west side of the Black zircon grains in this study, from many differ- considered, and so any undated, undiscovered, Bay fault (Fig. 2) have dominant populations ent ages, exhibit overgrowth rims, we interpret eroded, or buried potential source rocks could centered around 2.30 Ga and secondary peaks that these rims formed during postdepositional not be assessed in our study. The Precambrian around 2.10 Ga. These samples both contain a metamorphic events. geologic record itself is inherently incomplete. similar range of zircon ages (2540–1850 Ma). Additionally, much of the Canadian Shield has Age of the Upper Murmac Bay Group only been mapped and dated at a reconnaissance DISCUSSION level; however, as more data become available U-Pb ages younger than ca. 2.00 Ga were over time, this method will benefit from an Assessing Metamorphic versus Igneous obtained either from overgrowth rims, or from increasingly robust data set. Origin of Zircon Grains zircon grains that exhibited evidence of altera- Approximately 2800 spatially referenced tion of the original oscillatory growth band- potential source rocks were identified for zir- Care was taken to interpret the YDZ in each ing in CL and/or BSE images, such as con- con grains in these samples within the Cana- sample by choosing grains that did not show voluted zones propagating through fractures dian Shield (Fig. 5), as identified from igneous significant alteration textures or that might indi- (Corfu et al., 2003; Hoskin and Schaltegger, crystallization ages recorded in the DateView cate metamorphic zircon growth by Th/U ratios. 2003), recrystallization, or metamorphism database; Rae and neighboring cratons are high- The Th/U ratio reflects the crystallization envi- (Fig. DR1), which might have occurred prior lighted in green (Fig. 5). Potential sources for ronment of the zircon, with Th/U >0.2 indicat- to transport and deposition, or may represent dominant populations of 3.90–3.60 Ga in the

ing crystallization from a melt and Th/U <0.07 mixed ages. The interpreted YDZ grains in our lower Murmac Bay Group samples L2 and L3

associated with metamorphic zircon (Hoskin samples were dated at 2005 ± 18 Ma (U1), 1999 were found solely on the neighboring Slave

and Schaltegger, 2003; Rubatto, 2002). Th/U ± 9 Ma (U2), and 1989 ± 29 Ma (U3), giving a craton, though there are a number of potential ratios similar to or greater than magmatic values weighted mean of 1999 ± 13 Ma. The dominant source locations for the 2.70–2.30 Ga popula-

have been recorded, however, in metamorphic population in zircon aged younger than this is tions from samples L1 and L3 proximal to the zircon (Möller et al., 2003; Timms et al., 2006). centered around 1.93 Ga, which corresponds study area on the Rae craton, as well as on Möller et al. (2003) suggested that low Th/U to the aforementioned ca. 1.93 Ga crosscut- neighboring cratons. may be an indicator of metamorphic zircon ting Donaldson Lake pluton and ca. 1.93 to ca. To narrow the search for sources for the growth only in a system where other phases 1.91 Ga metamorphic monazite ages (Bethune upper Murmac Bay Group, only Paleoprotero- such as monazite and allanite compete for Th. et al., 2013). Although a single ca. 1.97 Ga zoic (2.50–1.90 Ga) potential source locations The Th/U ratio may also be affected during grain is not within error of known metamorphic are plotted in Figure 6, and it can be seen that metamorphism by a grain boundary fluid phase events or our YDZ age, a second spot in the there are a great number of candidates for the with a high Th/U value, or an enrichment in Th same domain of this grain yielded a younger dominant populations ca. 2.30 Ga in samples

relative to U in response to deformation due age of ca. 1.91 Ga, suggesting the U-Pb age U1, U2, and U3. A close-up view of the study to differential element mobility (Timms et al., of this grain could represent a mixed age. We area highlights the lack of ca. 2.17 Ga source 2006). Thus, Th/U may not always be in itself a interpret zircon grains from our samples with candidates for the dominant populations from

robust indicator of metamorphic zircon growth ages 2.00 Ga as having been metamorphosed samples U3 and U4 locally on the Rae craton and must be combined with observations from or otherwise altered after deposition. The three (Fig. 7). Potential sources for this ca. 2.17 Ga imaging as well. Only four zircon analyses in grains≲ aged between 1.93 Ga and 1.98 Ga all are age mode can be found, however, on the neigh- our study yielded Th/U ratios less than 0.07, two within error of either known metamorphism at boring Slave and Buffalo Head cratons, the ages of which were obtained from rims in sample ca. 1.93 Ga or our interpreted maximum dep- of which are identified in Figure 7.

U1 (Fig. DR2). ositional age. These, as well as other grains Visual analysis was an important factor in that exhibit alteration textures, might also have Provenance of the Lower Murmac Bay distinguishing whether the targeted analysis been affected by Pb loss, either before or after Group spots came from metamorphic or igneous sec- deposition, resulting in erroneously young ages. tors of the zircon grains. Zircon grains picked Therefore, we interpret the YDZ age in our The maturity of the quartzite in the lower for this study exhibited a pitted surface texture samples to be 1999 ± 13 Ma (weighted mean), Murmac Bay Group indicates a long period characteristic of detrital zircon. Most zircon representing a new maximum depositional age of weathering, erosion, and transportation that grains in the three samples had overgrowth rims constraint for the upper Murmac Bay Group in could support an interpretation of far-traveled that were very dark in CL images; one such rim its type locality. sediment sources. The only 3.90–3.60 Ga

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provenance locations identified from this study proximal potential source locations (e.g., North with previous work asserting this possibility are located in the Acasta Gneiss complex on Shore plutons; Hartlaub et al., 2007), as well as (Ashton et al., 2013; Bethune et al., 2013). Our the Slave craton (Fig. 5), though rocks of this more distal locations from the neighboring Talt- contribution widens this gap by another ~160 age are globally quite rare. Ages for the Acasta son orogen, Buffalo Head–Chinchaga domain, m.y., which would allow for up to an ~320 m.y. Gneiss complex include tonalitic gneisses dated and Slave craton (Fig. 6). Thus, the ca. 2.33 unconformity between the lower and upper Mur- at 3611 ± 11 Ma (Bowring and Williams, 1999) Ga age mode is also not a unique age mode for mac Bay Group. and 3661 ± 47 Ma (Iizuka et al., 2007), corre- determining provenance via the methods of this sponding to dominant age modes from samples study. The maturity of the quartzite in the lower Provenance of the Upper Murmac Bay

L2 and L3 (Fig. 4). Also, a granitic and a quartz Murmac Bay Group is consistent with a distal Group dioritic gneiss from the Acasta region were inter- source for these sediments; hence, the proximal preted to have crystallized at 3941 ± 43 Ma and ca. 2.30 Ga plutonic rocks (Hartlaub et al., 2007) The paucity of Archean grains in the upper 3931 ± 34 Ma, both with overgrowths suggesting might not be the most likely source. However, ca. Murmac Bay Group samples, along with the anatexis or a recrystallization event at 3689 ± 2.50–2.30 Ga rocks of the Arrowsmith orogeny abundance of grains aged <2.33 Ga, is consistent 61 Ma and 3677 ± 49 Ma, respectively (Iizuka along the western and northern margins of the with a shift in sediment source between depo- et al., 2007). Yamashita et al. (2000) examined Rae craton (Berman et al., 2005, 2013) could sition of the upper and lower successions. The a series of clastic sedimentary rocks proximal permissibly be a source of detritus of this age hiatus between deposition of the upper and lower to the Acasta Gneiss complex with depositional recorded in the psammopelitic to pelitic rocks Murmac Bay Group could permissibly have been

ages ranging from ca. 3.13 Ga to ca. 2.58 Ga, of the upper Murmac Bay Group (U1, U2, and up to ~320 m.y. Only one sample (U4) from

and reported depleted mantle model ages (TDM) U3). Th/U ratios less than 0.1 were also found in the upper Murmac Bay Group has a dominant ages between 3.70 and 2.90 Ga, including three a few grains aged 2.33–2.35 Ga (Fig. DR2) in Archean population ca. 2.60 Ga. Detrital zircon zircon grains with U-Pb ages older than 3.40 the upper Murmac Bay Group samples, which grains from the nearby Thluicho Lake Group Ga The authors suggested that the disagreement can be attributed to Arrowsmith orogenesis. The also exhibit dominant populations of this age,

between U-Pb and TDM ages may be due to Pb- neighboring Thluicho Lake Group also contains which were attributed to proximal widespread loss shifting the apparent U-Pb age younger than abundant detrital zircon of Arrowsmith age felsic plutonism in the Rae craton ca. 2.64–2.58 the actual crystallization, as the rocks described (2.47–2.25 Ga; Bethune et al., 2010). Ga (Skulski and Villeneuve, 1999; Bethune et were interpreted to have undergone extensive While there is a dominant age population at al., 2010). crustal reworking and recycling. Although lim- ca. 2.33 Ga in both the upper and lower Mur- The 2.15–2.19 Ga dominant age modes pres-

ited Eoarchean crustal preservation might be a mac Bay Group, the upper Murmac Bay Group ent in samples U3 and U4 correspond to only contributing factor to the paucity of other iden- shows several dominant age populations that a few potential sources identified on the Slave tified sources for zircon grains of this age, the are younger than this. If ca. 2.33 Ga represents craton and Buffalo Head–Chinchaga domain Acasta Gneiss complex is still permissible as the maximum depositional age of the lower unit (Table 2); therefore, it is an ideal detrital zircon a sediment source for the lower Murmac Bay and ca. 2.17 Ga represents that of the upper unit age population with which to investigate prov- Group, though other as-yet unidentified sources (Ashton et al., 2013), then a hiatus of at least enance. Figure 7 highlights the potential sources might exist. 160 m.y. between deposition of the upper and for these zircon populations (centered around ca. Many potential source locations were iden- lower Murmac Bay Group is possible. There- 2.17 Ga), the most proximal being in the Blatch-

tified for zircon in sample L3 with a dominant fore, it is permissible that the boundary between ford Lake intrusive suite on the Slave craton, age mode of 2.65–2.75 Ga, both proximally on the upper and lower Murmac Bay Group rep- which intrudes the ca. 2.68 Ga Burwash Forma- the Rae craton (Ashton et al., 2013), and on the resents a significant unconformity, consistent tion turbidites (Bleeker et al., 2004). Interpreted neighboring Hearne and Slave cratons (Fig. 5) as 2.70 Ga granite-greenstone belts. Rae cra- ton potential sources include plutonic rocks in TABLE 2. SUMMARY OF POTENTIAL PROVENANCE CANDIDATES FOR THE CA. 2.17 GA DOMINANT the Snowbird Lake region near the boundary DETRITAL ZIRCON AGE POPULATION FROM THE UPPER MURMAC BAY GROUP between the Rae and Hearne cratons (Martel et Sample ID Crystallization TechniqueDescription Reference age al., 2008). The Thluicho Lake Group, a metased- (Ma) imentary succession deposited <1.92–1.82 Ga in the neighboring Zemlak domain, also has a Slave craton minor population of detrital zircon grains that 79-132175 ± 5TIMSHearne Channel Granite– Bowring et al. (1984) Blatchford Lake intrusive suite fall within this age range and are interpreted 90TL-162176 ± 1.3TIMSGrace Lake Granite–Blatchford Sinclair et al. (1994) to have been locally derived (Bethune et al., Lake intrusive suite 2010). If the sediment transport was directed 600A 2164 ± 11 LA-ICPMS Nechalacho Layered Suite– Mumford (2013) from the Acasta Gneiss complex to the Murmac Blatchford Lake intrusive suite 1201A 2177 ± 1.6TIMSThor Lake Syenite–Blatchford Mumford (2013) Bay Group, there exist several potential sources Lake intrusive suite for this age mode between these locations in the VN-92-XX 2180 ± 1TIMSSqualus Lake alkaline intrusion Villeneuve and current craton configuration. Thus, ca. 2.70 Ga van Breemen (1994) is not a unique age population from which to Buffalo Head–Chinchaga domain distinguish sediment source. Chevron Irving Cadotte2165 ± 5TIMSCore from Buffalo Head terrane Villeneuve et al. (1993) Likewise, the 2.30–2.38 Ga dominant pop- Chevron et al Sheldon 2159 ± 11 TIMS Core from Chinchaga lowVilleneuve et al. (1993) ulations seen in samples from both the upper Pan Am A-1 Bald Mt 2175 ± 2TIMSCore from Chinchaga lowVilleneuve et al. (1993) and lower Murmac Bay Group are centered Note: TIMS—thermal ionization mass spectrometry; LA-ICP-MS—laser-ablation–inductively coupled plasma– around ca. 2.33 Ga and correspond to several mass spectrometry.

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crystallization ages for possible sources within or denudation of previous source rocks, exhu- and the Murmac Bay Group, confirming it as the Blatchford Lake intrusive suite include: the mation of new sources associated with tectonic a potential source for sediments in the lower Nechalacho layered suite at 2164 ± 11 Ma (LA- activity (Ashton et al., 2013), or evolution of Murmac Bay Group, though other as-yet undis- ICP-MS; Mumford, 2013), the Hearne Chan- drainage pathways. We consider the possibility covered potential sources might exist. nel granite at 2175 ± 5 Ma (TIMS; Bowring et of a potentially long-lived unconformity (Ash- The ca. 2.17 Ga dominant age population al., 1984), the Grace Lake granite at 2176 ± 1 ton et al., 2013; Bethune et al., 2013) to be plau- in the upper Murmac Bay Group samples has Ma (TIMS; Sinclair et al., 1994), and the Thor sible, based on the time gap indicated by our two possible provenance locations, the most Lake syenite at 2177 ± 2 Ma (TIMS; Mumford, new age constraints. Since sediment was most proximal being the Blatchford Lake intrusive 2013). A more distal potential source candidate likely sourced from the direction of the more suite located on the Slave craton, and also from on the Slave craton is the Squalus Lake alkaline proximal Blatchford Lake intrusive suite of the within the Buffalo Head–Chinchaga domain in intrusion to the north of the Blatchford Lake Slave craton, the ca. 2.30 Ga zircon grains were Alberta, the latter of which is currently bur- intrusive suite, with an interpreted crystalliza- most reasonably sourced either locally, or from ied under Phanerozoic cover. Geographically tion age at 2180 ± 1 Ma (TIMS; Villeneuve and the Taltson basement complex. The depositional between the Blatchford Lake intrusive suite and van Breemen, 1994). Three samples from core age constraints of the upper Murmac Bay Group the Murmac Bay Group, there are several poten- in the Buffalo Head–Chinchaga domain, which (<2.00 Ga to >1.93 Ga) suggest a connection tial source rocks that could provide the source is currently buried beneath Phanerozoic cover, with the Taltson orogen. The likelihood of sedi- for the ca. 2.33 Ga dominant age peaks seen were interpreted to have crystallized at 2159 ± ment sources from the Slave craton and/or Buf- in the upper Murmac Bay Group, along with 11 Ma, 2165 ± 5 Ma, and 2175 ± 2 Ma (TIMS; falo Head domain supports the hypothesis that several proximal sources; however, there are Villeneuve et al., 1993), respectively. the upper Murmac Bay Group was deposited in fewer candidates for zircon aged between 2.00 The upper Murmac Bay Group samples also the foreland of the Taltson orogen. and 2.14 Ga, dominantly ca. 2.13 Ga, which contain a large number of grains ranging in age are located geographically between the Blatch- from 2.00 to 2.14 Ga. The nearby 2.13–2.09 CONCLUSIONS ford Lake intrusive suite and the Murmac Bay Ga Rutledge River metasedimentary succession Group in the Taltson basement complex. We (Taltson) contains a population of 2.17–2.13 Ga New detrital zircon geochronological data thus conclude that the most likely provenance detrital zircon grains and records metamorphic from the upper Murmac Bay Group constrain source from currently known potential sources zircon and monazite growth at ca. 2.09–2.06 the maximum depositional age of this succes- contained within the database for the ca. 2.17 Ga (Bostock and van Breemen, 1994). A few sion at 1999 ± 13 Ma, which represents the Ga detrital zircon is the Blatchford Lake intru- grains from this study exhibit Th/U ratios that weighted mean of the three youngest detrital sive suite. Consequently, the ca. 2.33 Ga con- may be indicative of metamorphic origin (<0.2) zircon ages. By comparing our new data with tributions to the Murmac Bay Group are likely within the same age range as the Rutledge River previously published geochronological data for to have been sourced locally or by the Taltson metamorphic zircon (Fig. DR2). Gneisses in the the Murmac Bay Group (Fig. 4; Table 1), we basement complex. Evidence from proximity, subsurface from the Buffalo Head–Chinchaga were able to assess the differences in age popu- overlap in timing, and now provenance supports domain also record crystallization ages between lations between the upper and lower units of the the interpretation that the upper Murmac Bay ca. 2.09 Ga to 2.07 Ga and 2.19 Ga to 2.16 Ga Murmac Bay Group. While the lower unit con- Group was deposited in the foreland of the Talt- (Villeneuve et al., 1993). A syenogranite gneiss tains only early Paleoproterozoic and Archean son orogenic belt. from the Taltson basement complex has been detrital zircon grains (3.95–2.33 Ga), the upper The most probable identified sources of both dated at ca. 2.14 Ga, though the majority of unit is dominated by <2.33 Ga zircon grains and the 3.90–3.60 Ga and 2.17 Ga detrital zircon the metaplutonic gneisses in this complex have exhibits a distinct lack of zircon grains older grains are located on the Slave craton, indicat- ages ca. 2.40–2.30 Ga (McNicoll et al., 2000). than 2.33 Ga. Our findings reinforce the idea ing that the Slave and Rae cratons would have These potential sources from the Taltson base- of a long-lived hiatus in deposition between been proximal during the time of Murmac Bay ment complex lie geographically between the the upper and lower Murmac Bay Group based Group deposition in order for the Slave craton ca. 2.17 Ga provenance candidate locations and on this difference in dominant age populations to have contributed to Murmac Bay Group sedi- the Murmac Bay Group (Fig. 6). This suggests and disparity in inferred depositional ages, dur- ments. The youngest detrital zircon grains in the that sediment transport could have been directed ing which time there was a change in sediment lower Murmac Bay Group place timing of initial from either the Slave craton or Buffalo Head source to the Murmac Bay Group basin (Ashton deposition in the Murmac Bay basin after 2.33 domain during the time of deposition of the et al., 2013; Bethune et al., 2013). Additionally, Ga. Thus, the Rae and Slave cratons would have upper Murmac Bay Group. U-Pb results of zircon overgrowth rims of 1931 to have been proximal sometime after 2.33 Ga ± 11 Ma and 1917 ± 15 Ma in our study agree in order for the Slave craton to be a sediment Provenance Summary with metamorphic monazite ages (Bethune et source for the lower Murmac Bay Group sedi- al., 2013). ments, if sediments in the lower unit indeed The detrital zircon U-Pb age data from our The dominant age peaks in the lower Mur- originated from the Acasta Gneiss complex. The samples highlight the lack of Archean grains mac Bay Group point to the Acasta Gneiss com- two cratons would have remained in proximity in the upper Murmac Bay Group. As noted plex as a possible provenance location, as these during the deposition of the upper Murmac Bay in Ashton et al. (2013), detrital zircon grains are the only known exposed rocks within the Group. The upper Murmac Bay Group shows a in the upper Murmac Bay Group are primar- database with crystallization ages matching the distinct shift in sediment source, possibly due to

ily younger than 2.33 Ga, whereas detrital zir- 3.90–3.60 Ga peaks seen in samples L2 and L3. new tectonic activity resulting from amalgama- con grains in the lower unit are all ≥2.32 Ga, Provenance candidates matching younger peaks tion of the Slave and Rae cratons, or from accre- which demonstrates a shift in sediment source in lower Murmac Bay Group samples (2.70 Ga tion of the Buffalo Head–Chinchaga domain to between the upper and lower Murmac Bay and 2.33 Ga) are located both locally, and geo- the already sutured Rae and Slave cratons (Card Group. This shift could be the result of burial graphically between the Acasta Gneiss complex et al., 2014).

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With our interpreted sediment transport into Bethune, K.M., Hunter, R.C., and Ashton, K.E., 2010, Age and Mineralogy and Geochemistry, v. 53, p. 1–25, doi:10.2113​ ​ provenance of the Paleoproterozoic Thluicho Lake Group /0530001. the Murmac Bay Group basin being directed based on detrital zircon U-Pb SHRIMP geochronology: Gehrels, G.E., McClelland, W.C., Samson, S.D., Patchett, P.J., from the present-day north and west, we see New insights into the protracted tectonic evolution of the and Jackson, J.L., 1990, Ancient continental margin as- no unambiguous contribution from the Hearne southwestern Rae Province, Canadian Shield: Precam- semblage in the northern Coast Mountains, southeast brian Research, v. 182, p. 83–100, doi:10​ .1016​ /j​ .precamres​ ​ Alaska and northwest Canada: Geology, v. 18, p. 208–211, craton in these Murmac Bay Group sediments, .2010​.07​.003. doi:10​ .1130​ /0091​ -7613​ (1990)018​ <0208:​ ACMAIT>2​ .3​ .CO;2.​ and thus are unable to determine its position Bethune, K.M., Berman, R.G., Rayner, N., and Ashton, K.E., Hanmer, S., Williams, M., and Kopf, C., 1995a, Modest move- relative to the Rae craton in this study. 2013, Structural, petrological and U-Pb SHRIMP geochro- ments, spectacular fabrics in an intracontinental deep- nological study of the western Beaverlodge domain: Im- crustal strike-slip fault: Striding-Athabasca mylonite zone, Determination of sedimentary provenance plications for crustal architecture, multi-stage orogenesis NW Canadian Shield: Journal of Structural Geology, v. 17, in polydeformed terranes faces numerous chal- and the extent of the Taltson orogen in the SW Rae craton, p. 493–507, doi:​10​.1016​/0191​-8141​(94)00070​-G. Canadian Shield: Precambrian Research, v. 232, p. 89–118, Hanmer, S., Williams, M., and Kopf, C., 1995b, Striding- lenges, particularly if primary sedimentary doi:​10​.1016​/j​.precamres​.2013​.01​.001. Athabasca mylonite zone: Implications for the Archean structures are altered or erased by deformation. Bleeker, W., Ketchum, J., Davis, B., Sircombe, K., Stern, R., and early Proterozoic tectonics of the western Canadian Tracer isotopic analysis (e.g., Hf) can serve as and Waldron, J., 2004, The Slave Craton from on top: Shield: Canadian Journal of Earth Sciences, v. 32, p. 178– The crustal view [abs.], in The Lithoprobe Celebratory 196, doi:​10​.1139​/e95​-015. a next step to further elucidate sediment prov- Conference: From Parameters to Processes—Revealing Hartlaub, R.P., Heaman, L.M., Ashton, K.E., and Chacko, T., 2004, enance and tectonic setting. The methods pre- the Evolution of a Continent: Toronto, Ontario, Canada, The Archean Murmac Bay Group: Evidence for a giant Lithoprobe, p. 1–5. Archean rift in the Rae Province, Canada: Precambrian sented in this paper are a first step in identifying Bostock, H.H., and van Breemen, O., 1994, Ages of detrital Research, v. 131, p. 345–372, doi:​10​.1016​/j​.precamres​ potential sediment sources and highlight a prac- and metamorphic zircons and monazites from a pre- .2004.01​ .001.​ tical application for integrating large geochro- Taltson magmatic zone basin at the western margin of Hartlaub, R.P., Heaman, L.M., Simonetti, A., and Böhm, C.O., Rae Province: Canadian Journal of Earth Sciences, v. 31, 2006, Relicts of Earth’s earliest crust: U-Pb, Lu-Hf, and nological databases into provenance analysis. p. 1353–1364, doi:​10​.1139​/e94​-118. morphological characteristics of >3.7 Ga detrital zircon Bowring, S.A., and Williams, I.S., 1999, Priscoan (4.00–4.03 of the western Canadian Shield, in Reimold, W.U., and ACKNOWLEDGMENTS Ga) orthogneisses from northwestern Canada: Contribu- Gibson, R.L., eds., Processes on the Early Earth: Geologi- tions to Mineralogy and Petrology, v. 134, p. 3–16, doi:10​ ​ cal Society of America Special Paper 405, p. 75–89, doi:​ Field and analytical work were funded by a Geo-mapping .1007​/s004100050465. 10​.1130​/2006​.2405​(05). for Energy and Minerals (GEM-2) grant to Partin; Shiels was Bowring, S.A., Van Schmus, W.R., and Hoffman, P.F., 1984, Hartlaub, R.P., Heaman, L.M., Chacko, T., and Ashton, K.E., supported by the Natural Sciences and Engineering Research U-Pb zircon ages from Athapuscow aulacogen, East Arm 2007, Circa 2.3-Ga magmatism of the Arrowsmith orog- Council of Canada Graduate Scholarships-Master’s Program. of Great Slave Lake, N.W.T., Canada: Canadian Journal of eny, Uranium City region, western Churchill craton, Can- K. Ashton (Saskatchewan Geological Survey) is thanked for Earth Sciences, v. 21, p. 1315–1324, doi:​10.1139​ /e84​ ​-136. ada: The Journal of Geology, v. 115, p. 181–195, doi:10​ ​ providing additional samples for this study. This is a contri- Card, C.D., Ashton, K.E., and Bethune, K.M., 2010, The case .1086​/510641. bution to International Geoscience Programme (IGCP) 648 for separate Taltson and Thelon orogenies: Evidence from Hoffman, P.F., 1988, United plates of America, the birth of a “Supercontinent Cycles and Global Geodynamics.” K. Bethune, the Shield in western Saskatchewan [abs.], in Proceed- craton: Early Proterozoic assembly and growth of Lauren- J. Jones, and one anonymous reviewer are thanked for their ings of GeoCanada 2010: Calgary, Alberta, Canada, Cana- tia: Annual Review of Earth and Planetary Sciences, v. 16, suggestions that improved the clarity of the manuscript. dian Society of Petroleum Geologists, p. 1–4. p. 543–603, doi:​10​.1146​/annurev​.ea​.16​.050188​.002551. Card, C.D., Bethune, K.M., Davis, W.J., Rayner, N., and Ash- Horton, B.K., Hassanzadeh, J., Stockli, D.F., Axen, G.J., Gillis, REFERENCES CITED ton, K.E., 2014, The case for a distinct Taltson orogeny: R.J., Guest, B., Amini, A., Fakhari, M.D., Zamanzadeh, Evidence from northwest Saskatchewan, Canada: Pre- S.M., and Grove, M., 2008, Detrital zircon provenance of Ashton, K.E., Knox, B., Bethune, K.M., and Rayner, N., 2007, cambrian Research, v. 255, no. 1, p. 245–265, doi:​10.1016​ ​ Neoproterozoic to Cenozoic deposits in Iran: Implications Geochronological Update and Basement Geology along /j​.precamres​.2014​.09​.022. for chronostratigraphy and collisional tectonics: Tectono- the Northern Margin of the Athabasca Basin East of Fond- Chacko, T., De, S.K., Creaser, R.A., and Muehlenbachs, K., 2000, physics, v. 451, p. 97–122, doi:​10​.1016​/j​.tecto​.2007​.11​.063. du-Lac (NTS 74O/06 and/07), Southeastern Beaverlodge– Tectonic setting of the Taltson magmatic zone at 1.9–2.0 Hoskin, P.W., and Schaltegger, U., 2003, The composition of Southwestern Tantato Domains, Rae Province: Saskatch- Ga: A granitoid-based perspective: Canadian Journal of zircon and igneous and metamorphic petrogenesis: Re- ewan Ministry of Energy and Resources Summary of Earth Sciences, v. 37, p. 1597–1609, doi:​10.1139​ /e00​ ​-029. views in Mineralogy and Geochemistry, v. 53, p. 27–62, Investigations Miscellaneous Report 2007–4.2, 22 p. Collo, G., Astini, R.A., Cawood, P.A., Buchan, C., and Pimen- doi:​10​.2113​/0530027. Ashton, K.E., Hartlaub, R.P., Heaman, L.M., Morelli, R.M., Card, tel, M., 2009, U-Pb detrital zircon ages and Sm-Nd iso- Iizuka, T., Komiya, T., Ueno, Y., Katayama, I., Uehara, Y., C.D., Bethune, K., and Hunter, R.C., 2009, Post-Taltson topic features in low-grade metasedimentary rocks of Maruyama, S., Hirata, T., Johnson, S.P., and Dunkley, D.J., sedimentary and intrusive history of the southern Rae the Famatina belt: Implications for late Neoproterozoic– 2007, Geology and zircon geochronology of the Acasta Province along the northern margin of the Athabasca early Palaeozoic evolution of the proto-Andean margin Gneiss complex, northwestern Canada: New constraints Basin, western Canadian Shield: Precambrian Research, of Gondwana: Journal of the Geological Society, Lon- on its tectonothermal history: Precambrian Research, v. 175, p. 16–34, doi:​10​.1016​/j​.precamres​.2009​.09​.004. don, v. 166, p. 303–319, doi:​10​.1144​/0016​-76492008​-051. v. 153, p. 179–208, doi:10​ .1016​ /j​ .precamres​ .2006​ .11​ .017.​ Ashton, K.E., Hartlaub, R.P., Bethune, K.M., Heaman, L.M., Corfu, F., Hanchar, J.M., Hoskin, P.W.O., and Kinny, P., 2003, Knox, B., 2011, A Geological Investigation of the South-Cen- Rayner, N., and Niebergall, G.R., 2013, New depositional Atlas of zircon textures: Reviews in Mineralogy and Geo- tral Beaverlodge Domain, Southern Rae Province: With age constraints for the Murmac Bay Group of the south- chemistry, v. 53, p. 469–500, doi:10​ .2113​ /0530469.​ Emphasis on the Nature and Timing of Deformation and ern Rae craton, Canada: Precambrian Research, v. 232, Corrigan, D., Pehrsson, S., Wodicka, N., and de Kemp, E., 2009, Associated Metamorphism [M.Sc. thesis]: Regina, Sas- p. 70–88, doi:​10​.1016​/j​.precamres​.2012​.05​.008. The Palaeoproterozoic Trans-Hudson orogen: A proto- katchewan, Canada, University of Regina, 192 p. Aspler, L.B., and Chiarenzelli, J.R., 1998, Two Neoarchean type of modern accretionary processes, in Murphy, J.B., Knox, B., Bethune, K.M., Ashton, K.E., Williams, M.L., and supercontinents? Evidence from the Paleoproterozoic: Keppie, J.D., and Hynes, A.J., eds., Ancient Orogens and Rayner, N., 2008, U-Pb SHRIMP and chemical monazite Sedimentary Geology, v. 120, p. 75–104, doi:10​ ​.1016​ Modern Analogues: Geological Society, London, Special geochronology of rocks in the central Beaverlodge do- /S0037​-0738​(98)00028​-1. Publication 327, p. 457–479, doi:​10​.1144​/SP327​.19. main, Saskatchewan: Constraints on ages of rock units Berman, R.G., Davis, W.J., and Pehrsson, S., 2007, Colli- De, S.K., Chacko, T., Creaser, R.A., and Muehlenbachs, K., and implications for the tectonic evolution of the SW Rae sional Snowbird tectonic zone resurrected: Growth of 2000, Geochemical and Nd-Pb-O isotope systematics province [abs.], in Abstracts: Mineralogical Association Laurentia during the 1.9 Ga accretionary phase of the of granites from the Taltson magmatic zone, NE Alberta: of Canada, v. 33, p. 86. Hudsonian orogeny: Geology, v. 35, p. 911–914, doi:​10​ Implications for early Proterozoic tectonics in western Martel, E., van Breemen, O., Berman, R.G., and Pehrsson, S., .1130​/G23771A​.1. Laurentia: Precambrian Research, v. 102, p. 221–249, doi:​ 2008, Geochronology and tectonometamorphic history Berman, R.G., Pehrsson, S., Davis, W.J., Ryan, J.J., Qui, H., 10​.1016​/S0301​-9268​(00)00068​-1. of the Snowbird Lake area, Northwest Territories, Canada: and Ashton, K.E., 2013, The Arrowsmith orogeny: Geo- Eglington, B.M., 2004, DateView: A Windows geochronology New insights into the architecture and significance of the chronological and thermobarometric constraints on its database: Computers & Geosciences, v. 30, p. 847–858, Snowbird tectonic zone: Precambrian Research, v. 161, extent and tectonic setting in the Rae craton, with im- doi:​10​.1016​/j​.cageo​.2004​.06​.002. p. 201–230, doi:​10​.1016​/j​.precamres​.2007​.07​.007. plications for pre-Nuna supercontinent reconstruction: Eglington, B., 2013, FitPDF: http://sil.usask.ca/Software.htm McDonald, B., and Partin, C.A., 2016, Is the Lomagundi event Precambrian Research, v. 232, p. 44–69, doi:​10​.1016​/j​ (accessed 26 February 2016). present on the Rae craton? A case study from the Mur- .precamres​.2012​.10​.015. Eglington, B.M., Pehrsson, S.J., Ansdell, K.M., Lescuyer, J.-L., mac Bay Group: Canadian Journal of Earth Sciences, Berman, R.G., Sanborn-Barrie, M., Stern, R.A., and Carson, Quirt, D., Milesi, J.-P., and Brown, P., 2013, A domain-based v. 53, p. 457–465, doi:​10​.1139​/cjes​-2015​-0186. C.J., 2005, Tectonometamorphism at ca. 2.35 and 1.85 Ga digital summary of the evolution of the Palaeoproterozoic McDonough, M.R., McNicoll, V.J., Schetselaar, E.M., and Grover, in the Rae domain, western Churchill Province, Nunavut, of North America and Greenland and associated uncon- T.W., 2000, Geochronological and kinematic constraints on Canada: Insights from structural, metamorphic and in formity-related uranium mineralization: Precambrian Re- crustal shortening and escape in a two-sided oblique-slip situ geochronological analysis of the southwestern Com- search, v. 232, p. 4–26, doi:10​ .1016​ /j​ .precamres​ .2013​ .01​ .021.​ collisional and magmatic orogen, Paleoproterozoic Taltson mittee Bay belt: Canadian Mineralogist, v. 43, p. 409–442, Finch, R.J., and Hanchar, J.M., 2003, Structure and chem- magmatic zone, northeastern Alberta: Canadian Journal doi:​10​.2113​/gscanmin​.43​.1​.409. istry of zircon and zircon-group minerals: Reviews in of Earth Sciences, v. 37, p. 1549–1573, doi:10​ .1139​ /e00​ -089.​

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McNicoll, V.J., Thériault, R.J., and McDonough, M.R., 2000, supracrustal assemblages of the Rae domain, Nunavut, Paleoproterozoic metasedimentary rocks along the east- Taltson basement gneissic rocks: U-Pb and Nd isotopic Canada: Intracratonic basin development during super- ern margin of Hearne craton: Constraints from SHRIMP constraints on the basement to the Paleoproterozoic continent break-up and assembly: Precambrian Research, geochronology, Wollaston Group, Saskatchewan, Can- Taltson magmatic zone, northeastern Alberta: Canadian v. 181, p. 167–186, doi:​10​.1016​/j​.precamres​.2010​.06​.005. ada: Precambrian Research, v. 167, p. 171–185, doi:​10​ Journal of Earth Sciences, v. 37, p. 1575–1596, doi:10​ .1139​ ​ Regan, S.P., Williams, M.L., Leslie, S., Mahan, K.H., Jercinovic, .1016​/j​.precamres​.2008​.08​.003. /e00​-034. M.J., and Holland, M.E., 2014, The Cora Lake shear zone, Villeneuve, M.E., and van Breemen, O., 1994, A Compilation of Möller, A., O’Brien, P.J., Kennedy, A., and Kröner, A., 2003, Athabasca granulite terrane, an intraplate response to U-Pb Age Data from the Slave Province, Northwest Terri- Linking growth episodes of zircon and metamorphic far-field orogenic processes during the amalgamation tories: Geological Survey of Canada Open-File 2972, 53 p. textures to zircon chemistry: An example from the ul- of Laurentia: Canadian Journal of Earth Sciences, v. 51, Villeneuve, M.E., Ross, G.M., Thériault, R.J., Miles, W., Par- trahigh-temperature granulites of Rogaland (SW Nor- p. 877–901, doi:​10​.1139​/cjes​-2014​-0015. rish, R.R., and Broome, J., 1993, Tectonic Subdivision and way), in Vance, D., Müller, W., and Villa, I.M., eds., Geo- Rubatto, D., 2002, Zircon trace element geochemistry: Parti- U-Pb Geochronology of the Crystalline Basement of the chronology: Linking the Isotopic Record with Petrology tioning with garnet and the link between U-Pb ages and Alberta Basin, Western Canada: Geological Survey of and Textures: Geological Society, London, Special Pub- metamorphism: Chemical Geology, v. 184, p. 123–138, Canada Bulletin 447, 86 p. lication 220, p. 65–81, doi:10​ .1144​ /GSL​ .SP​ .2003​ .220​ .01​ .04.​ doi:​10​.1016​/S0009​-2541​(01)00355​-2. Weislogel, A.L., Graham, S.A., Chang, E.Z., Wooden, J.L., Geh- Morelli, R.M., Hartlaub, R.P., Ashton, K.E., and Ansdell, K.M., Sinclair, W.D., Hunt, P.A., and Birkett, T.C., 1994, U-Pb Zircon rels, G.E., and Yang, H., 2006, Detrital zircon provenance 2009, Evidence for enrichment of subcontinental litho- and Monazite Ages of the Grace Lake Granite, Blatchford of the Late Triassic Songpan-Ganzi complex: Sedimentary spheric mantle from Paleoproterozoic intracratonic mag- Lake Intrusive Suite, Slave Province, Northwest Territo- record of collision of the North and South China blocks: mas: Geochemistry and U-Pb geochronology of Mar- ries: Geological Survey of Canada, Radiogenic Age and Geology, v. 34, p. 97–100, doi:10​ .1130​ /G21929​ .1.​ tin Group igneous rocks, western Rae craton, Canada: Isotopic Studies Report 8, p. 15–20. Wodicka, N., St-Onge, M.R., Corrigan, D., Scott, D.J., and Wha- Precambrian Research, v. 175, p. 1–15, doi:​10​.1016​/j​ Skulski, T., and Villeneuve, M., 1999, Geochronological Com- len, J.B., 2014, Did a proto-ocean basin form along the .precamres​.2009​.04​.005. pilation of the Rae and Hearne Provinces: http://geoscan​ southeastern Rae cratonic margin? Evidence from U-Pb Mumford, T.R., 2013, Petrology of the Blatchford Lake Intru- .ess.nrcan​ .gc​ .ca​ /cgi​ -bin​ /starfinder​ /0​ ?path​ =geoscan​ .fl​ &id​ ​ geochronology, geochemistry (Sm-Nd and whole-rock), sive Suite, Northwest Territories, Canada [Ph.D. thesis]: =fastlink​&pass=&search=R%3D210204&format=FLFULL and stratigraphy of the Paleoproterozoic Piling Group, Ottawa, Canada, Carleton University, 239 p. (accessed March 2016). northern Canada: Geological Society of America Bulletin, Partin, C.A., Bekker, A., Sylvester, P.J., Wodicka, N., Stern, R.A., Stern, RA, 1997, The GSC Sensitive High Resolution Ion Micro- v. 126, p. 1625–1653. Chacko, T., and Heaman, L.M., 2014, Filling in the juvenile probe (SHRIMP): Analytical techniques of zircon U-Th-Pb Yamashita, K., Creaser, R.A., and Villeneuve, M.E., 2000, In- magmatic gap: Evidence for uninterrupted Paleoprotero- age determinations and performance evaluation, in Ra- tegrated Nd isotopic and U-Pb detrital zircon system- zoic plate tectonics: Earth and Planetary Science Letters, diogenic Age and Isotopic Studies: Report 10: Geologi- atics of clastic sedimentary rocks from the Slave Prov- v. 388, p. 123–133, doi:​10​.1016​/j​.epsl​.2013​.11​.041. cal Survey of Canada, Current Research I997-F, p. 1–31 ince, Canada: Evidence for extensive crustal reworking Pehrsson, S.J., Berman, R.G., and Davis, W.J., 2013, Paleo- Thomas, W.A., Astini, R.A., Mueller, P.A., Gehrels, G.E., and in the early- to mid-Archean: Earth and Planetary Sci- proterozoic orogenesis during Nuna aggregation: A case Wooden, J.L., 2004, Transfer of the Argentine Precordil- ence Letters, v. 174, p. 283–299, doi:​10.1016​ /S0012​ -821X​ ​ study of reworking of the Rae craton, Woodburn Lake, lera terrane from Laurentia: Constraints from detrital- (99)​00265​-4. Nunavut: Precambrian Research, v. 232, p. 167–188, doi:​ zircon geochronology: Geology, v. 32, p. 965–968, doi:​ 10​.1016​/j​.precamres​.2013​.02​.010. 10​.1130​/G20727​.1. Persons, S.S., 1988, U-Pb Geochronology of Precambrian Timms, N.E., Kinny, P.D., and Reddy, S.M., 2006, Enhanced Rocks in the Beaverlodge Area, Northwestern Saskatch- diffusion of uranium and thorium linked to crystal plas- MANUSCRIPT RECEIVED 7 MARCH 2016 ewan: Lawrence, Kansas, University of Kansas, Geol- ticity in zircon: Geochemical Transactions, v. 7, p. 10, doi:​ REVISED MANUSCRIPT RECEIVED 11 JULY 2016 ogy, 144 p. 10​.1186​/1467​-4866​-7​-10. MANUSCRIPT ACCEPTED 4 AUGUST 2016 Rainbird, R.H., Davis, W.J., Pehrsson, S.J., Wodicka, N., Tran, H.T., Ansdell, K.M., Bethune, K.M., Ashton, K., and Rayner, N., and Skulski, T., 2010, Early Paleoproterozoic Hamilton, M.A., 2008, Provenance and tectonic setting of Printed in the USA

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