New U-Pb Geochronological Results from the Seal River Region, Northeastern Manitoba (Parts of NTS 54L, M, 64I, P) by N

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GS-2 Far North Geomapping Initiative: new U-Pb geochronological results from the Seal River region, northeastern Manitoba (parts of NTS 54L, M, 64I, P) by N. Rayner1

Rayner, N. 2010: Far North Geomapping Initiative: new U-Pb geochronological results from the Seal River region, northeastern Manitoba (parts of NTS 54L, M, 64I, P); in Report of Activities 2010, Manitoba Innovation, Energy and Mines, Manitoba Geological Survey, p. 23–35.

Summary map of the Seal River region (see The Manitoba Geological Survey’s Far North Geo- Anderson et al., GS-1, this vol- mapping Initiative includes collaboration with the Geo- ume; Anderson et al., 2010). chronology Laboratory of the Geological Survey of Canada under the Geo-mapping for Energy and Minerals Regional geology (GEM) program. As part of this collaboration, this report In northeastern Manitoba, the southeastern margin presents new U-Pb zircon ages from 16 plutonic, volcanic of the Hearne craton is divided into several geologi- and sedimentary rocks from the Seal River region in far cal domains distinguished by the proportions of cover northeast Manitoba. The U-Pb geochronological results and possible basement rocks, and to a lesser extent, by presented here and interpreted in the accompanying report their structural trends and metamorphic grade. The area (Anderson et al., GS-1, this volume) record a protracted investigated in 2008 and 2009 includes portions of the and complex geological history. Mesoarchean (2901 Nejanilini and Seal River domains, and is bounded to ±5 Ma; 2860 ±4 Ma) basement rocks along with remnants the south by the Wathaman-Chipewyan plutonic com- of older, Paleoarchean (3.5 Ga) material have been identi- plex (Figure GS-2-1). The Nejanilini Domain is domi- fied in a discrete crustal block (the Seal River Complex) nated by granulite-grade metaplutonic rocks, with minor in the central portion of the map area. Emplacement of a enclaves of metasedimentary rocks, and is interpreted to voluminous felsic plutonic suite occurred in the Neoar- include vestiges of the Meso- to Neoarchean basement of chean between 2570 Ma and 2550 Ma and coincides in the Hearne craton. The Seal River Domain, in contrast, time with the crystallization age of a rhyolite flow (2570 is characterized by the presence of widespread metasedi- ±3 Ma) overlying the Seal River Complex. Of particular mentary rocks of generally lower metamorphic grade (the importance for regional tectonic correlations is a new Great Island Group of Schledewitz, 1986), which is newly chronology of four sedimentary sequences. Uranium- subdivided into four chronologically distinct sequences lead zircon ages indicate a Neoarchean depositional age (Anderson et al., GS-1, this volume). (<2.70 Ga; >2.57 Ga) for the fluvial-alluvial sequence 1, which includes mineralized quartz pebble conglomerate. Within the Seal River Domain, Mesoarchean and Provenance profiles also provide maximum depositional Neoarchean basement rocks at the Hearne craton margin ages for overlying marginal marine to marine siliciclas- are composed of multicomponent orthogneiss and hetero- tic rocks of sequence 2 (<2.5 Ga), sequence 3 (<1.98 Ga) geneous biotite (±hornblende) granite–granodiorite that and sequence 4 (<1.88 Ga), and thus provide important are discordantly cut by dikes of biotite granodiorite, horn- new constraints for regional stratigraphic correlations and blende diorite, feldspar porphyry and diabase, collectively paleotectonic reconstructions. referred to as the Seal River intrusive complex by Ander- son et al. (2009a, b), but is now referred to as the Seal River Complex (Anderson et al., GS-1, this volume). Separating Introduction these dominantly plutonic rocks from younger siliciclas- New mapping of Manitoba’s far north was initiated in tic sequences are mafic to felsic volcanic, volcaniclastic 2008 with a scoping study and continued with a focused and epiclastic rocks of the Sosnowski Lake assemblage, effort in 2009 and 2010 to answer fundamental questions which were described in detail by Anderson et al. (2009a) pertaining to the Precambrian geology and mineral poten- based on mapping in the Great Island area. This assem- tial of northern Manitoba. Manitoba’s far north provides blage is in turn unconformably overlain by structurally key exposures of metasedimentary cover successions, complex, though relatively intact, synclinal basins filled including rare exposures of metavolcanic rocks, and con- with continental and marine siliciclastic rocks previously tains several important mineral occurrences. This report referred to as the Great Island Group (Schledewitz, 1986; presents new U-Pb geochronological results from 16 sam- Anderson et al., 2009a), but is now subdivided into four ples collected during the 2008 and 2009 field seasons that chronologically distinct sequences (1–4) based on new provide absolute age constraints for the revised geological mapping in the eastern Seal River Domain (Anderson

1 Geological Survey of Canada, Natural Resources Canada, 601 Booth Street, Ottawa, Ontario, K1A 0E8

Report of Activities 2010 23 630,000 680,000 730,000

Paleozoic Nejanilini Domain Seal River Domain Intrusive and supracrustal rocks Sequence 4 (<1.88 Ga) Na6 Biotite granite, leucogranite, granitic pegmatite Sp8–Sp13 Greywacke-mudstone turbidites, iron formation, Na5 Potassium feldspar porphyritic granite; 'fresh' quartz arenite, marble Na4 Potassium feldspar porphyritic granite; recrystallized Intrusive rocks 1 Na3 Mafic granulite Sp6–Sp7 Biotite-muscovite granite (±garnet, fluorite), pegmatite Na2 Paragneiss Sequence 3 (<1.98 Ga) Na1 Unseparated biotite±hornblende granite, granodiorite Sp2–Sp5 Quartz arenite, mudstone, marble Fault Sp1 Iron formation (silicate facies) Geological contact Sequence 2 (<2.5 Ga) Dikes inferred from magnetics 0 0 0 0 0 0 , Sap5 Basalt Mp1 Gabbro (ca. 1.27 Ga Mackenzie swarm) , 0 0 5 5 6 Sap4 Gabbro 6 , Sap4 Gabbro , 6 Sap3 Psammitic and semipelitic paragneiss 6 Np1 Diabase? (ca. 2.45 Ga Kaminak swarm?) Sap2 Mudstone, arenite Mapping limit Sap1 Quartz arenite, conglomerate, mudstone Intrusive rocks (ca. 2.57–2.55 Ga) Sa19–Sa23 Syenogranite, quartz syenite, granite, granodiorite, quartz diorite, alaskite, pegmatite Sequence 1 (<2.7 Ga, >2.57 Ga) DRP Sa17–Sa18 Polymictic conglomerate, arenite, mudstone Intrusive rocks 2 Sa16 Serpentinite, peridotite, gabbro VLP Hudson Sa15 Biotite±hornblende granite, granodiorite, tonalite Bay Sosnowski Lake assemblage (ca. 2.7–2.6 Ga) Sa8–Sa14 Basalt, andesite, dacite, rhyolite; synvolcanic intrusions; derived volcaniclastic rocks 0 Seal River Complex 0 0 0 0 0 , Quartz- and feldspar-phyric rhyolite , 0 Sa6 0 0 0 6 6 , Sa1–Sa5, Sa7 Orthogneiss; granite, granodiorite; hornblende diorite, , 6 feldspar porphyry and diabase dikes 6

GLP Long Lake

Caribou Lake CRP

ain i Dom nilin main Neja r Do Rive Seal Warner Lake 0 Spruce Sosnowski 0 0 GLGB 0 0 0 , Naelin Lake Lake , 0 HLGB 0 5 Lake 5 5 5 , , 6 6

Meades Seal River Mullin Lake Lake Howard SBB Lake GIB Eppler Lake Seal River Great Island NLB

Nowell Lake Omand Lake NLP Nichol Lovat Lake Lake Teepee 0 0 0 Falls 0 0 0 , , 0 0 0 0 5 5 , , 6 6

North Knife River

0 20 40 kilometres

630,000 680,000 730,000

Figure GS-2-1: Simplified geology of the Seal River region in northern Manitoba (from Anderson et al., 2010). Abbrevia- tions: CRP, Caribou River pluton; DRP, Dickins River pluton; GIB, Great Island basin; GLGB, Garlinski Lake greenstone belt; GLP, Gross Lake pluton; HLGB, Howard Lake greenstone belt; NLB, Nowell Lake basin; NLP, Nichol Lake pluton; SBB, Seal Bend basin; VLP, Vinsky Lake pluton.

24 Manitoba Geological Survey et al., GS-1, this volume). These rocks are thought to be generate probability density diagrams. All ages quoted in partly correlative with the ca. 2.5–1.9 Ga Hurwitz Group the text are given at 2σ. in Nunavut (Aspler et al., 2001; Davis et al., 2005) and the comparatively well-dated ca. 2.1–1.9 Ga Wollaston Supergroup in Saskatchewan (Yeo and Delaney, 2007; Results Tran et al., 2008). As described by Anderson et al. (GS-1, this volume), intrusive rocks ranging in composition from Seal River Complex granite to peridotite are a significant component of the The Seal River Complex is well exposed in shore- Seal River Domain and provide important constraints on line outcrops on the Seal River downstream from Great the relative chronology of the principal map units. Island and displays evidence of multiphase diking that is not observed elsewhere in the map area. The distinctive aeromagnetic signature of the complex is suggestive of a Analytical methods discrete crustal block that has been enveloped by younger granitoid intrusions. As described by Anderson et al. (GS- Heavy minerals were separated from most rock sam- 1, this volume), the Seal River Complex is thought to rep- ples by standard crushing, grinding and heavy liquid tech- resent a remnant of older crust within the southern margin niques, followed by the sorting of heavy minerals using of the Hearne craton. a Frantz isodynamic separator. Electric-pulse disaggregation (EPD; Rudashevsky et al., 1995) was employed to comminute two of the samples. Zircons analyzed by iso- Sample 96-09-1177: granodiorite gneiss tope dilution–thermal ionization mass spectrometry (ID- This sample was collected from a 5 m thick sheet of TIMS) were treated with the chemical abrasion method homogeneous granodiorite in an outcrop of multicom- (Mattinson, 2005) before being submitted for U-Pb chem- ponent orthogneiss at the type locality of the Seal River istry. Dissolution of zircon in concentrated HF, extraction Complex downstream from Great Island. Based on cross- of U and Pb, and mass spectrometry followed the meth- cutting relationships, this orthogneiss is interpreted as ods described by Parrish et al. (1987). Data reduction and the oldest map unit in the complex. Abundant, elongate numerical propagation of analytical uncertainties follow to stubby prisms were recovered from the sample, which Roddick (1987). Analytical blanks for Pb were 1 pg. was disaggregated using the electric-pulse disaggregation Results are presented in Table GS-2-1. (EPD) method. Twenty-one zircons were analyzed by SHRIMP and the weighted mean 207Pb/206Pb age of 19 of Prior to sensitive high-resolution ion microprobe these analyses is 2901 ±5 Ma, which is interpreted as the (SHRIMP) analysis, the internal features of the zircons crystallization age of the granodiorite (Figure GS-2-2a). (zoning, structures, alteration, etc.) were characterized The youngest (2803 Ma) and oldest (2930 Ma) results with backscattered electrons (BSE) using a Zeiss Evo® were excluded from the calculation of the mean and scanning electron microscope. Detailed SHRIMP ana- are interpreted to reflect minor Pb loss and inheritance, lytical procedures and U-Pb calibration details are given respectively. in Stern (1997) and Stern and Amelin (2003). The ion microprobe results were collected on seven separate epoxy mounts with varying instrumental conditions. Sample 96-08-43-1: biotite granodiorite Specific analytical details for each sample are given in The older orthogneiss component of the Seal River the footnotes of the data table found in Data Reposi- Complex is crosscut by irregular dikes and thick sheets tory Item DRI20100042. An O– primary beam was used of texturally heterogeneous, light pink biotite±hornblende in all analytical sessions with an intensity ranging from granite and granodiorite, which are in turn crosscut by 3 to 12 nA. The count rates of ten isotopes of Zr+, U+, dikes of light grey biotite granodiorite. A sample of a dis- Th+ and Pb+ were sequentially measured over five scans cordant dike of biotite granodiorite was collected from with a single electron multiplier. The 1σ external errors an outcrop along the north shore of the Seal River, at of 206Pb/238U ratios reported in the data table incorporate the type locality east of Great Island. A relatively homo- an error between 1.0 and 1.6% in calibrating the standard geneous population of euhedral, prismatic zircons were zircon (Stern and Amelin, 2003). No fractionation cor- recovered from this sample. Based on their relatively rection was applied to the Pb-isotope data; the common simple appearance, TIMS analyses were carried out on Pb correction used the Pb composition of the surface five single-grain fractions treated using the chemical blank (Stern, 1997). Isoplot v. 3.00 (Ludwig, 2003) was abrasion method (Mattinson, 2005). Three of the five used to generate concordia plots and calculate weighted fractions yield concordant or near-concordant results of means. AgeDisplay (Sircombe, 2004) was used to 2861 Ma, 2858 Ma and 3458 Ma (Figure GS-2-2b). The

2 MGS Data Repository Item DRI2010004, containing the data or other information sources used to compile this report, is available online to down- load free of charge at http://www2.gov.mb.ca/itm-cat/web/freedownloads.html, or on request from [email protected] or Mineral Resources Library, Manitoba Innovation, Energy and Mines, 360–1395 Ellice Avenue, Winnipeg, Manitoba R3G 3P2, Canada

Report of Activities 2010 25 % 0.4 6.8 0.2 2.1 0.2 1.6 2.0 4.0 2.1 5.1 -0.3 Disc 1.4 1.4 1.5 1.3 1.2 1.3 1.3 1.3 1.4 1.5 1.5 ±2 σ ±2 Pb Pb 207 206 2860.8 2860.5 2857.8 3267.4 3458.2 2526.5 2519.3 2513.9 2424.8 2507.5 2370.7 8 2.2 2.2 2.3 2.3 2.2 2.0 2.1 2.0 2.0 2.1 2.1 ±2 σ U Pb 235 Ages (Ma) 207 2857.4 2793.1 2855.8 3246.5 3456.1 2529.7 2504.3 2495.4 2386.9 2487.5 2322.6 4.1 4.0 4.3 4.8 4.7 3.7 3.6 3.6 3.5 3.8 3.5 ±2 σ U Pb 238 206 2852.6 2700.8 2852.9 3212.8 3452.7 2533.6 2485.8 2472.7 2342.8 2463.1 2268.3 ±1 σ 0.00011 0.00009 0.00009 0.00010 0.00012 0.00007 0.00007 0.00006 0.00006 0.00007 0.00007 absolute Pb Pb 207 206 0.15711 0.20430 0.20425 0.20392 0.26345 0.29767 0.16688 0.16616 0.16562 0.16499 0.15219 7 Corr. Coeff. 0.93559 0.93480 0.92828 0.94741 0.94756 0.94756 0.94529 0.94729 0.94440 0.93424 0.93199 6 ±1 σ 0.00050 0.00047 0.00052 0.00061 0.00062 0.00042 0.00041 0.00041 0.00039 0.00043 0.00038 absolute U Pb Isotopic Ratios 238 206 0.55661 0.52038 0.55668 0.64605 0.70847 0.48144 0.47051 0.46753 0.43826 0.46533 0.42173 ±1 σ 0.01191 0.01170 0.01768 0.01677 0.01856 0.02720 0.03210 0.01217 0.01054 0.01219 0.01018 absolute U Pb 235 207 9.49369 8.84968 11.07744 15.67880 14.65485 15.65165 23.46733 29.07763 10.77927 10.67641 10.58601 U spike utilized in this study is 0.22% (2σ). 235 , fIn = few inclusions, rIn rare Eu euhedral, Pr prismatic, St stubby prism, Rnd round 150N Pb Pb U- 0.11 0.03 0.17 0.05 0.07 0.16 0.12 0.15 0.12 0.14 0.13 208 206 233 Pb- 5 205 3 3 4 1 2 2 3 1 1 1 1 Pb (pg) 4 Pb Pb 3924 3243 2599 5642 8264 9473 6525 204 206 27152 25026 21992 10849 3 Table GS-2-1: Isotope dilution–thermal ionization mass spectrometry (ID-TIMS) U-Pb results. Table 76 98 59 90 88 68 81 109 120 252 122 Pb (ppm) U 113 120 198 148 165 303 221 171 182 131 175 (ppm) 3 2 2 1 5 6 6 4 3 4 2 Wt. (ug) 2 Clr, Co, Rnd Clr, Description Clr, Br, St, rIn Br, Clr, Clr, Or, Pr, Eu Pr, Or, Clr, Eu Pr, Or, Clr, Eu Pr, Or, Clr, Eu Pr, Or, Clr, Clr, Or, Pr, Eu Pr, Or, Clr, Clr, Co, Pr, fIn Co, Pr, Clr, fIn Co, Pr, Clr, fIn Co, Pr, Clr, Clr, Co, St, rIn Clr, 1 Z = zircon fraction. All fractions were composed of a single grain, chemically abraded for 4 hours following the method Mattinson (2005). Z = zircon fraction. Zircon descriptions: Co = colourless, Br brown, Or orange, Clr clear Radiogenic Pb Measured ratio, corrected for spike and fractionation common Pb in analysis corrected for fractionation and spike Total Corrected for blank Pb and U common Pb, errors quoted are 1σ absolute; procedural values this study: 0.1 pg 1 Pb; Correlation coefficient Corrected for blank and common Pb, errors quoted are 2σ in Ma Fract. Z1C Z1D Z1E Z1F 96-08-26 (Z9850) charnockite gneiss, UTM: zone 14, 635721E 6562214N Z1 Z1B Z1C Z2 Z3 Z4 Notes: 1 2 3 4 5 6 Pb blank isotopic composition is based on the analysis of procedural blanks; corrections for common were made using Stacey-Kramers compositions. 7 8 The error on the calibration of Geological Survey Canada 96-08-43-1 (Z9851) biotite granodiorite, UTM: zone 14, 687408E 6521 Z1A

26 Manitoba Geological Survey 207Pb/206Pb age for one of the discordant analyses is identi- a) 0.63 cal within error to those of the two younger concordant 96-09-1177 (z10023) results. The weighted mean 207Pb/206Pb age of these three Granodiorite gneiss 0.61 analyses is 2860 ±4 Ma (Figure GS-2-2b, inset) and is interpreted to represent the crystallization age of the grano- 0.59 2980 diorite, while the Mesoarchean result is interpreted to rep-

U 2940 resent an inherited component. The fifth fraction yields

238 207 206 0.57 2900 a discordant Pb/ Pb age of 3267 Ma, which falls Pb/

206 2860 approximately along a chord between the magmatic and

0.55 2820 inherited components. Although a core-rim relationship 2780 Crystallization age was not clearly observed, this result might indicate the 0.53 2901 ±5 Ma presence of two components within the single analyzed n = 19 grain. MSWD = 1.08 0.51 13.5 14.5 15.5 16.5 17.5 18.5 207 235 Sample 96-08-40: quartz-phyric rhyolite b) Pb/ U A distinctive rhyolite flow at Thibeault Lake con- 96-08-43-1 (z9851) 0.70 3400 Z1F tains blue-quartz phenocrysts and very fine scale com- Biotite granodiorite positional layers, interpreted to represent flow banding. 3300 0.66 As described by Anderson et al. (GS-1, this volume), this Inherited component 3200 3464 ±15 Ma Z1E rhyolite is interpreted to represent the extrusive equiva- (upper intercept) U 2870 lent to high-level feldspar±quartz porphyry dikes that 238 0.62 3100 2850

Pb/ 2830 Z1D cut adjacent rocks of the Seal River Complex. Abundant Z1A 206 3000 2810 2790 zircons characterized by extensive fractures, inclusions 0.58 0.54 2900 and alteration were recovered. Due to the poor quality of Z1D 0.53 Crystallization age Z1A Z1C the zircons, the ion microprobe was employed to target 0.54 2860 ±4 Ma 0.52 MSWD = 5.0 the highest-quality portions of grains. All thirty analyzed Z1C 0.51 zircons yielded consistent results and a weighted mean 14.4 14.8 15.2 15.6 16.0 0.50 207Pb/206Pb age of 2570 ±3 Ma (mean square of weighted 14 18 22 26 30 207Pb/235U deviates [MSWD] = 1.0), which is interpreted as the crys- c) tallization age of the rhyolite (Figure GS-2-2c). 96-08-40 (z9849) 0.51 Quartz-phyric rhyolite 2600 Sosnowski Lake assemblage The Sosnowski Lake assemblage was defined by 0.49 2560 Anderson et al. (2009a) to consist mostly of subaqueous 2520 U mafic to intermediate lava flows and related intrusions, 238 0.47 2480 with minor intermediate to felsic volcanic rocks and thick Pb/ successions of unseparated volcaniclastic and epiclastic 206 rocks. Two samples of sandstone and one of quartz por- Crystallization age 0.45 phyry were analyzed to constrain the age of volcanism 2570 ±3 Ma n = 30 and sedimentation. MSWD = 1.0 0.43 10.2 10.6 11.0 11.4 11.8 12.2 Sample 97-09-280: volcanic sandstone 207 235 Pb/ U A sample from a felsic volcanic sandstone interlayer Figure GS-2-2: Uranium-lead zircon geochronological within pillowed and massive basalt flows at the type results from the Seal River Complex (ellipses on con- locality of the Sosnowski Lake assemblage southwest cordia diagrams are plotted at the 2σ uncertainty level; of Sosnowski Lake was collected to constrain the age MSWD = mean square of weighted deviates; Geological of the source felsic volcanic rocks. Abundant prismatic Survey of Canada lab numbers are given in parentheses zircons that vary from well faceted to slightly resorbed for each sample): a) concordia diagram showing sensitive high-resolution ion microprobe (SHRIMP) results from were recovered (Figure GS-2-3a, inset). Sixty-five detri- sample 96-09-1177; b) concordia diagram showing iso- tal zircons were analyzed by ion microprobe and yielded tope dilution–thermal ionization mass spectrometry (ID- a relatively simple provenance profile with a dominant TIMS) results from sample 96-08-43-1; inset illustrates mode at 2.7 Ga and three subordinate modes at 2.82, 3.2 a magnified view of the three fractions used to calculate and 3.4–3.45 Ga (Figure GS-2-3a). The youngest detrital the weighted mean age; c) concordia diagram showing grain with reproducible analyses yields an age of 2705 SHRIMP results from sample 96-08-40. ±5 Ma (n = 2), which is consistent with the dominant

Report of Activities 2010 27 0.030 16 a) 97-09-280 (z10019) 15 14 0.025 Volcanic sandstone 13 n = 63/65 12 90–110% conc. 11

0.020 Frequency 10 9 0.015 Youngest detrital zircon 8 7 Probability 2705 ±5 Ma 6 0.010 n = 2 replicates 5 MSWD = 1.0 4 0.005 3 2 1

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

Age (Ma) b) 0.014 11 96-08-38 (z9844) 10 0.012 Pebbly sandstone 9 n = 59/64, 90–110% conc. 0.010 8 Frequency 7 0.008 Youngest detrital zircon 6 2613 ±8 Ma 5 0.006 n = 3 replicates Probability MSWD = 0.6 4 0.004 3 2 0.002 1

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

Age (Ma) c) 0.66 97-09-222 (z10021) 0.62 Quartz-feldspar porphyry

0.58 Tentative crystallization age 2900 2679 ±6 Ma 2800 0.54 n = 5 U MSWD = 1.0 2700 238 0.50 2600 Pb/ 2500 206 0.46 2400

0.42

0.38

0.34 8 10 12 14 16

207Pb/235U

Figure GS-2-3: Uranium-lead geochronological results from the Sosnowski Lake assemblage (dark grey curves and histograms represent data that is within 10% of concordia; MSWD = mean square of weighted deviates; probability density diagrams do not include replicate analyses; ellipses on concordia diagrams are plotted at the 2σ uncertainty level): a) probability density diagram showing sensitive high-resolution ion microprobe (SHRIMP) results for sample 97-09-280; b) probability density diagram showing SHRIMP results for sample 96-08-38; c) concordia diagram showing SHRIMP results from sample 97-09-222; grey ellipse is excluded from the calculation of the weighted mean. Scale bar on inset photographs is 300 µm.

28 Manitoba Geological Survey detrital population; this is interpreted to represent the overlies felsic volcaniclastic rocks of the Sosnowski Lake most likely age of felsic volcanism in the Sosnowski Lake assemblage to the east. To the south and north, this basin assemblage north of the Seal River. is truncated by unconformities at the base of sequence 2 and sequence 3, respectively. Possible correlative rocks are also exposed in an anticlinal culmination in the area Sample 96-08-38: pebbly sandstone south of Spruce Lake, where they are crosscut by a variety The Sosnowski Lake assemblage southeast of Omand of intrusive rocks that are not observed in the overlying Lake includes distinctive units of polymictic conglomer- rocks of sequences 2 or 3, likewise indicating an uncon- ate and sandstone that are interstratified with intermedi- formable contact relationship. ate volcaniclastic rocks of apparently local derivation, but contain abundant well-rounded cobbles and boulders of apparently ‘exotic’ quartzite. A sample of pebbly sand- Sample 97-09-89: quartz pebble conglomerate stone from one of the conglomerate units was collected East of Omand Lake, the lower unit of sequence 1 for analysis. Abundant detrital zircons, many strongly contains interlayers of supermature quartz pebble con- rounded and frosted by mechanical abrasion during glomerate that locally contain anomalous concentrations transport, were recovered (Figure GS-2-3b, inset) and of Au, U and LREE, presumably associated with accumu- 64 were analyzed by SHRIMP. The provenance profile lated heavy minerals. A sample of fuchsitic quartz pebble is dominated by two populations at 2.7 Ga and 2.97 Ga conglomerate from this location was collected to constrain (Figure GS-2-3b); the younger peak is thought to be rep- the depositional age. The recovered zircons range from resentative of the locally sourced felsic volcanic detri- colourless through pale yellow/brown to pink and are large tus, whereas the older peak may be representative of the and morphologically diverse, with variably rounded, pris- dominant source of detritus in the sandstone precursor to matic to equant habits (Figure GS-2-4, lower, inset). The the exotic quartzite. A single, ancient, 3.58 Ga zircon was detrital sources identified in this sample are unique, domi- identified as well as two younger 2.6 Ga zircons. Three nated by 3.4 and 3.5 Ga zircons with a significant propor- replicates on a single grain (#61) were used to constrain tion of grains older than 3.6 Ga (Figure GS-2-4, lower). the age of the youngest detrital zircon, and thus the maxi- The oldest detrital zircon recognized is 3801 Ma. Four zir- mum age of deposition, to 2613 ±8 Ma. cons yielded ages of ca. 3.0 Ga and two others yielded ages of ca. 3.2 Ga. A single zircon dated at ca. 2.7 Ga constrains the maximum age of deposition of the conglomerate. Sample 97-09-222: quartz-feldspar porphyry A sample of a small plug of hypabyssal quartz- feldspar porphyry east of Omand Lake was collected to Intrusive rocks constrain the age of felsic volcanism in the southern por- The Seal River Domain includes a wide variety of tion of the Sosnowski Lake assemblage. This porphyry granitoid intrusive rocks that are known or inferred to is interpreted to be broadly coeval with adjacent felsic intrude supracrustal rocks of the Sosnowski Lake assem- volcanic rocks, and appears to be unconformably over- blage and sequence 1, but are not observed to cut the lain to the west by coarse fluvial-alluvial conglomerate unconformably overlying rocks of sequences 2–4. A rep- of sequence 1. Eleven poor-quality zircons were recov- resentative selection of these granitoid intrusions were ered from this sample. Only six zircons were of suitable sampled for analysis. quality for ion microprobe analysis, and despite a wide range in U concentrations (114–1085 ppm), all six grains Sample 97-09-134: syenogranite gave similar ages (Figure GS-2-3c). The weighted mean 207Pb/206Pb age of five of these analyses (excluding a sin- This sample was collected from an outcrop on the gle, young, high-U analysis) is 2679 ±6 Ma, which could Seal River upstream from Great Island, in the central por- be interpreted to represent the crystallization age of the tion of a large syenogranite and quartz syenite pluton that hypabyssal intrusion or the age of xenocrystic zircons. intrudes the Sosnowski Lake assemblage to the east and Regardless of interpretation, the 2.68 Ga date is thought sequence 1 to the north (Figure GS-2-1). A population of to closely approximate the age of felsic volcanism in this simple, prismatic, oscillatory zoned zircons was recov- portion of the Sosnowski Lake assemblage. ered and 17 grains were analyzed by ion microprobe. The weighted mean 207Pb/206Pb age of all the analyses is 2570 ±5 Ma (Figure GS-2-5a), which is interpreted as the crys- Sequence 1 tallization age. Given the crosscutting relationships, this Sedimentary rocks of sequence 1 consist of a lower age is also interpreted to represent the minimum age of the unit of interstratified arenite and polymictic conglomerate Sosnowski Lake assemblage and sequence 1, the latter of and an upper unit of quartz arenite, with only minor inter- which is thus constrained between 2.7 Ga and 2.57 Ga. The beds of conglomerate and mudstone. These rocks define a crystallization age of the syenogranite is identical, within narrow, north-trending, half-graben south of Great Island error, to the quartz-phyric rhyolite (sample 96-08-40; that is fault-bounded to the west and unconformably Figure GS-2-2c) that overlies the Seal River Complex.

Report of Activities 2010 29 0.025 46 44 97-09-228 (z10020) 42 40 Psammitic gneiss 38 0.020 n = 58/60, 36 34 90–110% conc. 32

30 Frequency 0.015 28 26 24 22 20 Probability 0.010 18 16 Youngest detrital zircon 14 2558 ±23 Ma 12 0.005 n = 3 replicates 10 8 MSWD = 0.6 6 4 2 0.000 0 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800

0.012 10

Sequence 2 Sequence 96-08-16 (z9845) 9 0.010 Quartz arenite n = 65/69, 8 90–110% conc. 7 0.008 Frequency 6

0.006 5 Youngest detrital zircon Probability 4 2504 ±25 Ma 0.004 n = 3 replicates 3 MSWD = 3.1 2 0.002 1

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

0.014 11

97-09-89 (z10018) 10 0.012 Quartz pebble conglomerate 9 n = 62/65, 0.010 90–110% conc. 8

7 Frequency 0.008 6

5 0.006 Probability

4 Sequence 1 Sequence 0.004 Youngest detrital zircon 3 2695 ±8 Ma 2 0.002 n = 3 replicates MSWD = 1.8 1

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

Age (Ma) Figure GS-2-4: Uranium-lead geochronological results from sedimentary sequences 1 and 2 (dark grey curves and histograms represent data that is within 10% of concordia; MSWD = mean square of weighted deviates; probability density diagrams do not include replicate analyses): (lower) probability density diagram showing sensitive high-resolution ion microprobe (SHRIMP) results for sample 97-09-89, from sequence 1 east of Omand Lake; (middle) probability density diagram showing SHRIMP results for sample 96-08-16, from sequence 2 at Teepee Falls on the North Knife River; (upper) probability density diagram showing SHRIMP results for sample 97-09-228, from sequence 2 west of Spruce Lake. Scale bar on inset photographs is 300 µm.

30 Manitoba Geological Survey Sample 96-08-28: quartz porphyry a) 0.53 This sample was collected from a large outcrop of 97-09-134 (z10226) quartz porphyry within a succession of interlayered aren- Syenogranite ite and polymictic conglomerate of sequence 1 south of 0.51 2660 2620 Spruce Lake. Abundant, simple, prismatic and well-faceted zircons were recovered and analyzed by ion micro- 2580 U 0.49 probe. Twenty-three low-U zircons yield a weighted mean 238 2540 207Pb/206Pb age of 2562 ±5 Ma (Figure GS-2-5b), which Pb/ 2500

206 is interpreted as the emplacement age of the quartz por- 0.47 2460 phyry. This age overlaps, within error, the crystallization Crystallization age age of the syenogranite intrusion to the south (sample 0.45 2570 ±5 Ma 97-09-134; Figure GS-2-5a) and thus confirms the ca. n = 17 2.57 Ga minimum age of deposition for sequence 1. A MSWD = 0.7 single high-U overgrowth on one of the zircons (962 ppm 0.43 10.0 10.4 10.8 11.2 11.6 12.0 12.4 12.8 U, Th/U = 0.02) is interpreted to represent a Paleoprotero- 207 235 zoic (ca. 1.80 Ga) metamorphic overprint that is rarely b) Pb/ U 0.56 recorded by zircons in the study area. 96-08-28 (z10224) 0.52 Quartz porphyry 2700 Sample 97-09-108: porphyritic granite 0.48 2500 Plutons composed of unseparated granite, granodio-

U rite and lesser quartz diorite intrude the Sosnowski Lake 0.44 238 2300 assemblage and, at least locally, define the margins of both

Pb/ the Garlinski Lake and Howard Lake greenstone belts

206 0.40 2100 (Figure GS-2-1). These plutons also appear to be exten-

0.36 Crystallization age sive beyond the margins of these belts, where they appear 1900 2562 ±5 Ma to include older gneissic components. A sample of homo- n = 23 0.32 MSWD = 1.2 geneous porphyritic granite northeast of Sosnowski Lake, 1700 close to the boundary zone with the Nejanilini Domain, 0.28 3 5 7 9 11 13 was collected for analysis and was disaggregated using 207 235 the EPD method. The zircons recovered from the granite c) Pb/ U 0.54 are simple, clear, colourless, well-faceted prisms with few 97-09-108 (z10022) fractures or inclusions. Nineteen zircons were analyzed

0.52 Porphyritic granite by ion microprobe and combined to a weighted mean 2660 207Pb/206Pb age of 2550 ±4 Ma (Figure GS-2-5c). This is 2620 0.50 the youngest intrusive rock documented within the Seal

U 2580 River Domain. 238 2540

Pb/ 0.48 2500 206 2460 Crystallization age Sequence 2 0.46 2420 2550 ±4 Ma Sequence 2 consists mostly of quartz arenite and n = 19 varicoloured mudstone, with subordinate gabbro sills and 0.44 MSWD = 1.1 amygdaloidal basalt flows that transition southward into andalusite-bearing paragneiss, schist and minor amphib- 0.42 olite that are intruded by synmetamorphic biotite–mus- 9.5 10.5 11.5 12.5 207 235 covite–garnet±fluorite granite and related pegmatite. Pb/ U To the north, sequence 2 unconformably overlies Neo- Figure GS-2-5: Uranium-lead geochronological results archean (≥2.55 Ga) orthogneiss, volcanoplutonic rocks from a selection of Archean granitoid intrusions from the and granitoid intrusions, as well as fluvial-alluvial silici- Seal River Domain (ellipses on concordia diagrams are clastic rocks of sequence 1. Sequence 2 is distinguished plotted at the 2σ uncertainty level; Geological Survey of from sequence 1 by the presence of coeval mafic flows Canada lab numbers are given in parentheses for each sample; MSWD = mean square of weighted deviates): and related intrusions, and the lack of coarse polymictic a) concordia diagram showing sensitive high-resolution conglomerate. Sequence 2 is also thought to include the ion microprobe (SHRIMP) results from sample 97-09- strongly transposed psammitic and semipelitic paragneiss 134, b) concordia diagram showing SHRIMP results from between Spruce Lake and Naelin Lake, which was provi- sample 96-08-28, c) concordia diagram showing SHRIMP sionally considered part of the ‘Omand Lake assemblage’ results from sample 97-09-108. by Anderson et al. (2009a).

Report of Activities 2010 31 Sample 96-08-16: quartz arenite et al. (2009a); the contact between these sequences is A sample of pebbly quartz arenite from a large out- interpreted to be an angular unconformity. crop near the base of sequence 2 at Teepee Falls on the North Knife River was collected for analysis. Large, Sample 96-08-15: quartz arenite prismatic zircons, ranging from colourless to pale yel- A sample of quartz arenite was collected from near the low/brown to pink, are predominantly well-rounded and base of sequence 3 downstream from Teepee Falls on the frosted from mechanical abrasion during transport (Fig- North Knife River, in close proximity to the basal contact ure GS-2-4, middle, inset). The detrital zircon provenance of flat-lying Ordovician sedimentary rocks of the Hudson profile is dominated by 2.7 Ga zircons with a subordinate Bay Basin. A heterogeneous population of well-faceted population of 2.8 Ga zircons and scattered results between to well-rounded zircons was recovered (Figure GS-2-6, 3.7 Ga and 2.9 Ga (Figure GS-2-4, middle). Though lower, inset). Many of the zircon grains are stained orange much less abundant, the distribution of results older than by iron oxide precipitate along fractures, perhaps as a 2.9 Ga in this sample is similar to that obtained from the result of Ordovician weathering. Sixty-four detrital zir- quartz pebble conglomerate of sequence 1. Four zircons cons were analyzed by ion microprobe and define a prom- yielded ages of ca. 2.56–2.50 Ga, which are representa- inent mode at 2.56 Ga, with a subordinate mode at 2.7 Ga tive of the granitoid intrusions described earlier. Three and rare results older than 2.8 Ga (Figure GS-2-6, lower). replicate analyses on the youngest detrital zircon yields The dominant 2.56 Ga mode is consistent with the ages of a mean 207Pb/206Pb age of 2504 ±25 Ma constraining the the granitoid intrusions described earlier. Two detrital zir- maximum age of deposition. cons confirm a Paleoproterozoic depositional age for this sequence, the youngest of which yields a mean 207Pb/206Pb Sample 97-09-228: psammitic paragneiss age of 2049 ±19 Ma. A sample of sequence 2 sillimanite-bearing psammitic paragneiss was collected 2 km west of the location Sample 96-08-29: quartz arenite where interbedded arenite and conglomerate of sequence 1 A sample of massive to faintly stratified, medium- to are discordantly cut by 2.56 Ga quartz porphyry (sample coarse-grained quartz arenite was collected from higher 96-08-28; Figure GS-2-5b). A homogeneous population up-section in sequence 3, on the north channel of the Seal of well-faceted, prismatic zircons was recovered and ana- River at Great Island. Zircons recovered from this sample lyzed by ion microprobe (Figure GS-2-4, upper, inset). All range from colourless to pale yellow and are typically but one of the 60 analyzed zircons defines a single statisti- rounded to subrounded (Figure GS-2-6, middle, inset). cal population centred at 2.56 Ga (Figure GS-2-4, upper). Most of the results fall within the range of 2.3–2.5 Ga, The youngest detrital zircon is dated at 2558 ±23 Ma, with sporadic older results up to 2.75 Ga (Figure GS-2- based on three replicate analyses of a single grain. A sin- 6, middle). The youngest detrital zircon with reproduc- gle detrital zircon records a slightly older age of 2.66 Ga. ible analyses is dated at 1984 ±14 Ma (weighted mean Given the proximity to the dated 2.56 Ga quartz porphyry, 207Pb/206Pb age of grain 100, four replicates), which is the unimodal population of 2.56 Ga detrital zircons in the considered the maximum depositional age of sequence 3. paragneiss sample is interpreted to indicate a very local source and thus a depositional contact relationship with sequence 1. Sample 96-08-32: greywacke turbidite A sample of coarse lithic greywacke was collected from near the base of sequence 4 in the Great Island basin Sequences 3 and 4 east of Meades Lake and is the stratigraphically highest Sedimentary rocks of sequences 3 and 4 define a analyzed sample in the Seal River Domain. Well-fac- series of prominent synclinal basins that, from west to eted, prismatic zircons characterized by numerous frac- east, include the Great Island, Seal Bend and Nowell Lake tures dominate the detrital zircon population; however, a basins, and are the defining characteristic of the southeast- subordinate population of well-rounded grains was also ern margin of the Hearne craton in Manitoba. Sequence 3 identified (Figure GS-2-6, upper, inset). The provenance includes a basal silicate facies iron formation, overlain by profile of the greywacke exhibits a more limited range of a thick succession of interlayered arenite, mudstone and ages compared to samples from the underlying sequences, minor lenses of dolomitic marble that likely records depo- with a prominent mode centred at 2.53 Ga and sporadic sition in a marine-deltaic setting. Sequence 4 includes younger ages (Figure GS-2-6, upper). Maximum age a lower section of dolomitic marble, calcsilicate rocks and of deposition of the greywacke is constrained by four oxide-facies iron formation, overlain by a thick succession replicate analyses on a single grain that yielded a of greywacke-mudstone turbidites, with minor iron for- weighted mean 207Pb/206Pb age of 1879 ±19 Ma. mation, thought to represent a basinal-marine depositional setting. Sequences 3 and 4 were referred to as the ‘lower’ and ‘upper’ Great Island Group, respectively, by Anderson

32 Manitoba Geological Survey 0.020 15 14 0.018 13 0.016 12 96-08-32 (z9843) 11 0.014 Greywacke turbidite 10 Frequency 0.012 n = 57/61, 90–110% conc. 9 Youngest detrital zircon 8 0.010 1879 ±19 Ma 7 n = 4 replicates Probability 0.008 MSWD = 0.3 6

Sequence 4 Sequence 5 0.006 4 0.004 3 2 0.002 1

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

0.009 6

0.008 5 0.007 96-08-29 (z9847) Youngest detrital Quartz arenite 0.006 4 Frequency zircon n = 59/60, 90–110% conc. 1984 ±14 Ma 0.005 n = 4 replicates, 3 MSWD = 0.5 0.004 Probability 0.003 2

0.002 1 0.001

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

0.030 18 17 Sequence 3 Sequence 16 0.025 15 96-08-15 (z9846) 14 13 Quartz arenite 0.020 12 Frequency n = 63/64, 90–110% conc. 11 Youngest detrital zircon 10 0.015 2049 ±19 Ma 9 n = 3 replicates 8 Probability MSWD = 0.3 7 0.010 6 5 4 0.005 3 2 1

0.000 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 0

Figure GS-2-6: Uranium-lead geochronological results from sequences 3 and 4 (dark grey curves and histograms represent data that is within 10% of concordia; probability density diagrams do not include replicate analyses; MSWD = mean square of weighted deviates): (lower) probability density diagram showing sensitive high-resolution ion microprobe (SHRIMP) results for sample 96-08-15 from sequence 3 downstream from Teepee Falls on the North Knife River; (middle) probability density diagram showing SHRIMP results for sample 96-08-29 from sequence 3 on the north side of Great Island; (upper) probability density diagram showing SHRIMP results for sample 96-08-32 from sequence 4 east of Meades Lake. Scale bar on inset photographs is 300 µm.

Report of Activities 2010 33 Nejanilini Domain intercept is anchored at the interpreted crystallization age The Nejanilini Domain is dominated by metaplutonic of 2526 Ma. This may reflect the Paleoproterozoic meta- rocks with minor enclaves of mafic granulite and para- morphic overprint recorded by zircon in sample 96-08-28 gneiss. Only a single sample from this domain, collected (Figure GS-2-5b). As described by Anderson et al. (GS- in 2008, has been analyzed to date. This domain was a 1, this volume), the significance of this result is unclear major focus of the 2010 mapping campaign and three in the context of the available U-Pb ages and field rela- additional samples have been submitted for geochrono- tionships in the Nejanilini Domain. Further analyses are logical analysis to resolve the age and possible correlation planned to resolve this problem. of the principal map units. Economic considerations The mapping and U-Pb age results presented here Sample 96-08-26: charnockitic gneiss and by Anderson et al. (GS-1, this volume) represent a A sample of charnockitic gneiss composed of honey- significant advancement in the understanding of the com- brown to green feldspar, quartz, hornblende and magne- plex nature, protracted evolution and diverse mineral tite was collected from the south margin of the Nejanilini potential of the southeastern Hearne craton margin, one of Domain northeast of Spruce Lake. Clear colourless zir- the last remaining frontier areas in Manitoba. Of particu- cons were recovered from the sample and separated into lar economic importance are the Archean age constraints four distinct morphologies: elongate prisms; stubby on an extensive and underexplored greenstone belt with prisms; stubby rounded grains; and turbid, rounded zir- known Au mineralization (the Sosnowski Lake assem- cons. Single-grain fractions of each of these morpholo- blage), which is the only known example in Manitoba’s gies were analyzed by TIMS after treatment by chemical far north. The geochronological results presented here abrasion (Mattinson, 2005). Despite their simple appear- support a revised stratigraphy of the Great Island Group ance, most of the fractions yielded discordant results. The (Schledewitz, 1986), comprising four diverse sedimentary elongate zircon population (Z1) yielded the three most sequences. Sequence 1 includes a fault-controlled fluvial- concordant fractions (Figure GS-2-7). The best estimate alluvial basin of Archean age south of Great Island that of the crystallization age of the granite is interpreted to contains U-Au-LREE–mineralized quartz pebble con- be the 207Pb/206Pb age of the most concordant fraction, glomerate. The first absolute age constraints from Paleo- 2526.5 ±1.3 Ma. Other more discordant fractions yield proterozoic siliciclastic rocks of sequences 2–4 facilitate 207Pb/206Pb ages between 2519 and 2371 Ma. All six frac- comparisons with better-studied and explored successions tions are approximately collinear and yield a lower inter- in Nunavut (Hurwitz Group) and Saskatchewan (Woll- cept of 1737 ±200 Ma, (MSWD = 87) when the upper aston Group) and thus provide a substantially upgraded

0.49 2550

0.48 96-08-26 (z9850) Z1 Charnockitic gneiss 2500

0.47 Z1B 2450 Z1C Z3 0.46 U

238 2400 0.45 Pb/

206 2350 0.44 Crystallization age Z2 2526.5 Ma ±1.3 Ma 207 206 2300 0.43 Pb/ Pb age of most concordant fraction (Z1)

0.42 Z4

0.41 8.4 8.8 9.2 9.6 10.0 10.4 10.8 11.2 11.6 207Pb/235U Figure GS-2-7: Concordia diagram of U-Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) results from sample 96-08-26 from the Nejanilini Domain (ellipses on the concordia diagram are plotted at the 2σ uncertainty level; Geological Survey of Canada lab number is given in parentheses).

34 Manitoba Geological Survey conceptual framework for mineral exploration in Manito- Parrish, R.R., Roddick, J.C., Loveridge, W.D. and Sullivan, ba’s far north. R.W. 1987: Uranium-lead analytical techniques at the geochronology laboratory, Geological Survey of Canada; in Radiogenic Age and Isotopic Studies: Report 1, Geological Acknowledgments Survey of Canada. v. 87-2, p. 3–7. Thanks are owed to R. Chung, R. Christie, T. Pestaj, Roddick, J.C. 1987: Generalized numerical error analysis with L. Cataldo, J. Peressini and C. Lafontaine of the Geochro- application to geochronology and thermodynamics; Geo- nology Laboratory at the Geological Survey of Canada chimica et Cosmochimica Acta, v. 51, p. 359–362. for their careful and excellent work in the generation of Rudashevsky, N.S., Burakov, B.E., Lupal, S.D., Thalhammer, the ages presented here. P. Hunt is thanked for assistance O.A.R. and Saini-Eidukat, B. 1995: Liberation of acces- in generating the scanning electron microscopy (SEM) sory minerals from various rock types by electric-pulse dis- images. The manuscript benefitted from thorough reviews integration—method and application; Transactions of the by S. Anderson, C. Böhm and N.Wodicka. Institute of Mining and Metallurgy, v. 104, p. 25–29. Natural Resources of Canada, Earth Science Sector Schledewitz, D.C.P. 1986: Geology of the Cochrane and Seal rivers area; Manitoba Energy and Mines, Geological Report contribution number 20100221. GR80-9, 139 p. Sircombe, K. 2004: AgeDisplay: an EXCEL workbook to eval- References uate and display univariate geochronological data using Anderson, S.D., Böhm, C.O. and Syme, E.C. 2010: Precam- binned frequency histograms and probability density distri- brian geology of the Seal River region, Manitoba (parts of butions; Computers & Geosciences, v. 30, p. 21–31. NTS 54L, M, 64I, P); Manitoba Innovation, Energy and Stern, R.A. 1997: The GSC sensitive high resolution ion micro- Mines, Manitoba Geological Survey, Preliminary Map probe (SHRIMP): analytical techniques of zircon U-Th-Pb PMAP2010-1, scale 1:175 000. age determinations and performance evaluation; in Radio- Anderson S.D., Böhm, C.O., Syme, E.C., Carlson A. and Mur- genic Age and Isotopic Studies, Report 10, Geological Sur- phy L.A. 2009a: Bedrock geology of the Great Island area, vey of Canada, Current Research 1997-F, p. 1–31. Manitoba (parts of NTS 54L13, 54M4, 64I15, 16, 64P1, Stern, R.A. and Amelin, Y. 2003: Assessment of errors in SIMS 2); Manitoba Innovation, Energy and Mines, Manitoba zircon U-Pb geochronology using a natural zircon stan- Geological Survey Preliminary Map PMAP2009-4, scale dard and NIST SRM 610 glass; Chemical Geology, v. 197, 1:75 000. p. 111–146. Anderson, S.D., Böhm, C.O., Syme, E.C., Carlson, A.R. and Tran, H.T., Ansdell, K.M., Bethune, K.M., Ashton, K. and Murphy, L.A. 2009b: Far North Geomapping Initiative: Hamilton, M.A. 2008: Provenance and tectonic setting of geological investigations in the Great Island area, Mani- Paleoproterozoic metasedimentary rocks along the eastern toba (parts of NTS 54L13, 54M4, 64I15, 16, 64P1, 2); in margin of Hearne craton: constraints from SHRIMP geo- Report of Activities 2009, Manitoba Innovation, Energy chronology, Wollaston Group, Saskatchewan, Canada; Pre- and Mines, Manitoba Geological Survey, p. 132–147. cambrian Research, v. 167, p. 171–185. Aspler, L.B., Wisotzek, I.E., Chiarenzelli, J.R., Losonczy, M.F., Yeo, G.M. and Delaney, G.D. 2007: The Wollaston Supergroup, Cousens, B.L., McNicoll, V.J. and Davis W.J. 2001: Paleo- stratigraphy and metallogeny of a Paleoproterozoic Wil- proterozoic intracratonic basin processes, from breakup of son cycle in the Trans-Hudson orogen, Saskatchewan; in Kenorland to assembly of Laurentia; Hurwitz Basin, Nuna- EXTECH IV: Geology and Uranium EXploration TECH- vut, Canada; Sedimentary Geology, v. 141–142, p. 287– nology of the Proterozoic Athabasca Basin, Saskatchewan 318. and Alberta; Geological Survey of Canada, p. 89–117, Davis, W.J., Rainbird, R.H., Aspler, L.B. and Chiarenzelli, J.R. Bulletin 588 and Saskatchewan Geological Society, Spe- 2005: Detrital zircon geochronology of the Paleoprotero- cial Publication 18 and Geological Association of Canada, zoic Hurwitz and Kiyuk groups; Geological Survey of Mineral Deposits Division, Special Publication 4, C.W. Canada, Current Research 2005-F1, 13 p. Jefferson and G.D. Delaney (ed.). Ludwig, K.R. 2003: User’s manual for Isoplot/Ex rev. 3.00: a geochronological toolkit for Microsoft Excel; Berkeley Geochronology Center, Special Publication 4, Berkeley, 70 p. Mattinson J.M. 2005: Zircon U–Pb chemical abrasion (“CA- TIMS”) method: combined annealing and multi-step partial dissolution analysis for improved precision and accuracy of zircon ages; Chemical Geology, v. 220, p. 47–66.

Report of Activities 2010 35