La Ronge ‘Horseshoe’ Project: Preliminary Bedrock Geology of the Bob-Miles Lakes Area at the Transition Between the Western Glennie Domain and Southern Rottenstone Domain (parts of NTS 73P/06)
Ralf O. Maxeiner
Maxeiner, R.O. (2011): La Ronge ‘Horseshoe’ project: preliminary bedrock geology of the Bob-Miles lakes area at the transition between the western Glennie Domain and southern Rottenstone Domain (parts of NTS 73P/06); in Summary of Investigations 2011, Volume 2, Saskatchewan Geological Survey, Sask. Ministry of Energy and Resources, Misc. Rep. 2011-4.2, Paper A-8, 14p.
This report is accompanied by the map separate(s) entitled: Maxeiner, R.O. (2011): Bedrock geology of the Bob Lake area, transition zone between Glennie and Rottenstone domains (NTS 73P/06); 1:20 000-scale prelim. geological map with Summary of Investigations 2011, Volume 2, Saskatchewan Geological Survey, Sask. Ministry of Energy and Resources, Misc. Rep, 2011-4.2.
Abstract Mapping at 1:20 000 scale was completed over a 70 km2 area centred on Bob Lake, at the transition zone between the western Glennie Domain and the southern Rottenstone Domain to the north. In the Glennie Domain, a succession of mafic volcanic and calc-silicate rocks, interpreted as variably deformed mafic volcanic flows and pillow basalts, was delineated in a series of fold (and thrust?)-repeated units that extend for tens of kilometres into the Nemeiben Lake area to the south and eastwards into the central Glennie Domain. The mafic volcanic rocks contain transposed gabbroic sheets. This mafic volcanoplutonic succession is structurally overlain by a partially migmatized, muscovite-biotite–bearing psammitic to psammopelitic succession east of Miles Lake. These sedimentary gneisses represent a component of the Rottenstone Domain. Although the contact between the two successions is generally highly strained, local gradational changes suggest that it might originally have been transitional in nature. The supracrustal rocks were intruded by abundant biotite tonalite-granodiorite plutons. Minor hornblende granodiorite gneisses, exposed southwest of Bob Lake, may represent an earlier episode of granitoid plutonism, as they appear to have a more complex structural history and are crosscut by biotite tonalite- granodiorite. A monzodioritic pluton, emplaced into the sedimentary succession east of Miles Lake, represents a distinct suite of intrusions that was also recognized in the Nemeiben Lake area in the previous year of mapping and was interpreted to have been emplaced prior to the regional D3 deformational event. Granitic pegmatite represents the youngest intrusive suite of the area.
Rare outcrop-scale, close to isoclinal folds deform transposed calc-silicate layering in the mafic volcanic rocks and bedding-parallel leucosome and S1 foliation in the sedimentary rocks. The Bob Lake structural dome is a result of fold interference, likely between north-trending, map-scale F3 folds and east-northeast–trending F4 folds. Biotite tonalite-granodiorite and the Miles Lake monzodiorite preserve weakly developed, generally steeply west-dipping S3 foliations. Presence of abundant muscovite, local sillimanite, and in situ granitic partial melt suggest that the metamorphic grade in the Bob-Miles lakes area was at the transition from middle to upper amphibolite facies conditions. Mineral occurrences between Bob and Nemeiben lakes are mostly hosted by mafic volcanic rocks, with lesser intermediate to mafic pluton-hosted and minor sediment-hosted mineralization. The sulphides range from disseminated to massive in texture and are dominated by pyrrhotite, with minor amounts of chalcopyrite and pyrite. The area has the potential to host volcanogenic massive sulphide deposits and gabbro-hosted Cu-Ni deposits. Mafic volcanic and calc-silicate rocks at Bob Lake and Miles Lake are likely part of the same successions of variably strained mafic volcanic-gabbroic rocks that host the Elizabeth Lake deposit on Nemeiben Lake, the Anglo Rouyn deposit at Waden Bay of Lac La Ronge, and the Pitching Lake deposit west of Trade Lake. Keywords: Glennie Domain, Rottenstone Domain, Paleoproterozoic, mafic volcanic rocks, volcanogenic massive sulphide, magmatic Ni-Cu.
Saskatchewan Geological Survey 1 Summary of Investigations 2011, Volume 2 1. Introduction In 2010, a new bedrock mapping project was initiated in the area of the La Ronge ‘Horseshoe’ (Pearson, 1974; Macdonald, 1987; Maxeiner and MacLachlan, 2010), an enigmatic zone of lower to upper amphibolite facies plutonic rocks, orthogneisses and supracrustal rocks that have been folded around a northeast-trending F4 structure (Lewry et al., 1990), to produce a southwest-facing horseshoe shape (Figure 1). Due to a lack of modern mapping and poor geological understanding of this structurally complex area, there have been a number of iterations of the lithotectonic framework for this southwestern-most part of the Reindeer Zone (Ashton, 1999). Although the domainal framework for the Precambrian Shield of Saskatchewan should be viewed only as a two-dimensional, mainly geographic subdivision of its complex three-dimensional infrastructure, it commonly tends to focus and guide mineral exploration. Unfortunately, the two-dimensional domainal classification can therefore sometimes hamper proper geological interpretation and misguide mineral exploration, as it can splice metallogenic domains. For example, the La Ronge Domain is commonly viewed as a gold belt, whereas the western Kisseynew Domain tends to be viewed more as a base-metal target. Yet many of the gold occurrences of the area between Hebden and Greywacke lakes, which is dominated by sedimentary successions that were formerly included as part of the La Ronge Domain, were more recently included in the Kisseynew Domain (Ashton, 1999). The area of the La Ronge ‘Horseshoe’ is underlain by many of the lithotectonic domains of the Reindeer Zone (Figure 1), with the Glennie Domain underlying much of the southern and eastern part, with the Rottenstone, La Ronge, and Kisseynew domains all converging in the north. The Bob-Miles lakes area contains elements of the western Glennie Domain and southern Rottenstone Domain. A companion paper (Maxeiner and Kamber, this volume) describes the results of another mapping project carried out as part of the La Ronge ‘Horseshoe’ project, which was centred on Hebden Lake in the transition zone between the Glennie, La Ronge, and Kisseynew domains.
There are a number of historic base-metal and gold showings and deposits within the ‘Horseshoe’ area, most of which can be classified into one of three categories: pelitic-mafic (Besshi-type) volcanic-associated massive sulphide (VMS) deposits, mafic-ultramafic intrusion-hosted Ni–Cu–platinum group element deposits, and structurally controlled mesothermal lode gold deposits (Rogers, 2011). An overview of the Elizabeth Lake VMS deposit and the Dunlop Cu-Ni deposit and their exploration history was given last year (Maxeiner and MacLachlan, 2010). Most of the exploration in the area around Bob Lake and towards Nemeiben Lake to the southwest dates back to the late 1960s, during which time a number of mineral occurrences were discovered by a variety of companies with follow-up work lasting until the mid-1980s. In the following 20 years, the area has only seen very sporadic exploration, but experienced a resurgence in 2008, when MacDonald Mines Exploration Ltd. (MacDonald Mines) acquired several dispositions centred on Bob Lake and flew a VTEM survey, followed up by mapping, a soil sampling program, and a diamond-drill program in the winter of 2009. Some of the MacDonald Mines diamond- drill holes were examined and assessed for rock protolith and style of mineralization during the course of the field work.
The 2011 field investigations were centered in two different areas, Bob Lake (Figure 2) and Hebden Lake (Maxeiner and Kamber, this volume), each of which were mapped by a three-person crew during two one-month periods. Both lakes can be accessed via float-equipped aircraft from La Ronge or Missinipe. An inflatable boat and canoe were used to navigate the lakes and reach lakeshore outcrops, while foot traverses were conducted to access outcrops located away from the lakeshores. A handheld Global Positioning System (GPS) unit was used to record locations during field work and accuracy of stations was generally ±5 to 10 m.
The topography of the Bob Lake area is fairly rugged with elevations varying from about 405 m at lake level to about 500 m on the granodiorite ridges surrounding the lake. The vegetation is dense, consisting of old growth forest with abundant spruce and poplar stands, with pine trees growing on granitoid ridges and areas of sandy soils. Juniper bushes and roses are common on the calc-silicate rocks surrounding the lake, particularly on ridge tops and south-facing hill sides. Most outcrops are covered by a thick layer of moss, reindeer lichen, and a variety of crustose lichen, the latter hampering identification of rock textures and mineralogy. A thin veneer of glacial till is common throughout the area, but percentage of bedrock exposure is about average for the Precambrian Shield of the province.
2. Previous Work and Exploration History The Bob-Nemeiben lakes area was mapped between 1966 and 1967 by Forsythe (1971) at a scale of 1:31,680 for the Saskatchewan Department of Mineral Resources. The only recorded exploration work in the immediate Bob Lake areas dates to the period between 1984 and 1987, and culminated in a 12-hole, 1530 m diamond-drill program completed in the fall of 1987 by Colray Resources Inc. All the drilling was focussed south of the lake, where the company was targeting shear zone–hosted gold mineralization. Most of the intersected sulphide mineralization consisted of <10% disseminated and fracture-bound pyrite, with minor amounts of chalcopyrite and pyrrhotite hosted in plutonic and minor sedimentary gneisses. No significant gold contents were encountered.
Saskatchewan Geological Survey 2 Summary of Investigations 2011, Volume 2 LEGEND RAE Km Manville Group HEARNE Prefix: Glennie Domain (G), Kisseynew Domain (K), La Ronge Domain (L), Rottenstone Domain (R) ATHABASCA PALEOPROTEROZOIC Plutonic Rocks and Probable ng Biotite-hornblende gneiss BASIN Plutonic Derivation Volcanic Rocks WB Wathaman Batholith iv Intermediate - felsic volcanic rock gt Tonalite Mafic - intermediate (felsic) vb Felsic orthogneiss - volcanic rock gn WB strongly foliated Amphibolite, mafic volcanic- LRD m HEARNE tonalite-granodiorite calc-silicate rock RD gd Granite-granodiorite- ARCHEAN (Sask Craton) tonalite, derived gneiss REINDEER AI Granite, quartz monzonite ZONE KD qd Diorite, tonalite Mylonitic orthogneiss GD bd Gabbro, diorite, Az Detail FFD ultramafic rock Trace of F4 fold axis Sedimentary Rocks SASK CRATON rn Arkose, conglomerate $ Selected Mineral Deposits (McLennan Group) WB Rng 102 Highway Number Rgt Psamite - pelite (conglomerate), 05 10 20 30km sn Settlement derived migmatite Rvb Lqd Rsn Rgd Rgt Rm WB
Rgd Liv Lgd Rng Rgd Rng 102 Lvb Rgt McIntosh Rsn WB Lake
Lgd Rgt Lgd WB Rm 55°45'’ Lm Krn Kbd WB Rng Lbd Ksn Ksn River Km Lgd Black Bear Liv Kgd Ggd Island Lake Missinipe Rgn Lbd Gm Churchill Az WB Krn Otter Km Lake Rng Ggd Gsn Rsn Lqd Kgd Lvb Figure 2 Lgd Hebden Lake Area WB Gsn Gm Bob Gm Lvb Krn 55°30' Gm Lake MacKay Hebden Miles Lake Lake Stanley Lake Ggd Rsn Mission Rng Ggd Ggn Lvb Gm Az Lgd Gsn Gm Ggd Gsn Elizabeth Lake Az Deposit$ 102 Gm 915 AI 0746 Lake Gu$ 0749 Gm Dunlop $ Ggd Deposit Anglo Rouyn Ggn Deposit Gsn Gqd Gm NemeibenGsn
Km Az
55°15' AI 2010 mappingGsn Lac La Ronge
105°30' 105°00' 104°30' Figure 1 – Simplified regional geological map showing outlines of the Bob and Hebden lakes map areas, as well as Nemeiben Lake (2010 mapping). Inset map: domainal framework of the Precambrian Shield of northern Saskatchewan. Abbreviations: FFD, Flin Flon Domain; GD, Glennie Domain; KD, Kisseynew Domain; LRD, La Ronge Domain; RD, Rottenstone Domain; and WB, Wathaman Batholith.
Saskatchewan Geological Survey 3 Summary of Investigations 2011, Volume 2
55°28'0"N
3 4 498000 m E
85 Ï Mdi Trace of FTrace axial surface Strike and dip of selected main foliation (S1/S2) Trace of FTrace axial surface
Zone of high strain Zone of abundant tonalitic material intruding 85 85 Psp
Ï
Ï 80 Ï
Mv
Ps
Ï Lake Miles Miles Gdm Symbol Legend 48 496000 m E
85 Ï
P Ï Mv
65 Gdq 85
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105°05' W
Psp 85 Ï 78
85
Lake Ï Sharpe Ï 84
494000 m E Ï 85 Gdq
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Ps Psammite (-psammopelite) Mv Mafic volcanic rock Ï Psp Migmatitic psammopelite (-psammite) Pcs Calcic psammopelite-psammite Mvc Layered mafic calc-silicate rock Supracrustal Rocks P 60 80 Ï Ï 75 Psp
83 Gdh Ï 80 T
Ï Ps
75
Ï Ï
35 Ï 492000 m E Ï 30 58 Tgl
32 Ï T 75
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Simplified geological map for the Bob Lake area. Ï Ï Ps –
Tgl
Mvc Mvc 70 Ï 62 Mvc
Ï Ï Ga
Pcs
Px
33
Ï
Ï Tgl
Lake Bob Bob Figure 2 41
Mv 44
Di Sheared diorite/microdiorite
Px Pyroxenite Ga Gabbro
Tgl Leucocratic felsic gneiss Gdh Hornblende granodiorite/leucogranodiorite Ï Gdm Granodiorite/leucogranodiorite gneiss T
Lake Ï McGuigan McGuigan T
85 490000 m E Ps Ï Ï Ï 48
Ga
80
80
75 km Ï Ï 80 Ï 3 P 85 105°10' W 75
Di
Pcs Ï
Ï T
Mvc 65
Mvc
Lake Ball Ball 68
80
21 Ï Ï Ï 85 Mv Ï Ga Ï 70 Gdh
85
488000 m E Ï 77 75 Di Ga
Ï Di 80 Ï 80 Ga T Biotite tonalite-granodiorite (-leucogranodiorite) T P Granite pegmatite, leucogranite P Mdi Monzodiorite (diorite, quartz diorite) Gdq Quartz-phyric granodiorite (-leucogranodiorite) 0
Intrusive Rocks Pre-dating Main Deformation Event
Syn- to Post-tectonic Intrusive Rocks
Lake Fold Fold
Legend
6148000 m N m 6148000 N m 6146000
N m 6144000
Saskatchewan Geological Survey 4 Summary of Investigations 2011, Volume 2 Subsequently, Macdonald Mines conducted exploration work in the immediate Bob Lake area and in a larger area extending towards Nemeiben Lake to the southwest. This work was filed for assessment credit with the Saskatchewan Ministry of Energy and Resources (SMER) in 2009; its details therefore are presently confidential. Based on a 2009 news release by the company, a series of high-strength electromagnetic conductors had been identified through a VTEM geophysical survey that was completed in 2008. After identifying 23 conductive anomalies, a surface exploration program was undertaken that involved geological mapping, prospecting, and grab sampling of selected areas, as well as an organic soil sampling program that uncovered multi-element geochemical anomalies in association with the geophysical anomalies. Sulphide mineralization enriched in Cu, Ni, Zn, and Ag was identified in the subcrop associated with the conductive anomalies. A 2000-m drill program to test eight of the targets was planned for the winter of 2009. The larger Bob-Nemeiben lakes area experienced episodic exploration work between 1968 and 1987 on the Sucker Lake showing (Saskatchewan Mineral Deposit Index (SMDI) #0747a), Muskwa Claims (SMDI #0748), National Nickel Drill Hole No. 3 (SMDI #0737), and the Nemeiben Lake (Bague Bay) Cu Occurrence (SMDI #0741), resulting mainly in the discovery of disseminated pyrrhotite-pyrite in hornblende-bearing sedimentary and or volcano-sedimentary gneisses. The Sucker Lake showing represents a Mo-Cu showing within a pegmatite intruding migmatitic pyrite-pyrrhotite–bearing sedimentary gneisses (SMER Assessment File 73P06-0070). The Nemeiben Lake (Bague Bay) Cu Occurrence consists of minor disseminated chalcopyrite and associated pyrrhotite-pyrite within a narrow gabbro body that (?)intrudes sedimentary gneisses. In 1996, two holes drilled by Peter Knudsen on claim S-105212 intersected disseminated to semi-massive pyrrhotite-pyrite mineralization in quartzofeldspathic sedimentary rocks (drill holes SK-2 and -3 of SMDI #2705). These holes were part of a nine-hole diamond-drilling program that was outlined by ground VLF-EM and magnetic surveys conducted the previous year (SMER Assessment File 73P06-0150).
3. Regional Geology The previous geological map for Bob Lake (Forsythe, 1971) shows the lake to be in the core of a structural dome that is defined by intercalated layered calc-silicate rocks (unit 4a of Forsythe) and layered felsic schists and gneisses (unit 7 of Forsythe). This structural dome is contained within extensive ‘felsic granitic rocks’ (Forsythe, 1971).
On a regional scale, the Bob Lake area has most recently been included as part of the western Glennie Domain and southern Rottenstone Domain (Ashton, 1999; Saskatchewan Geological Survey, 2003). Based on structural trends and bedrock compilations, mafic rocks making up the core of the Bob Lake structure and extending through Miles and Bob lakes, merge with similar units that can be traced to Elizabeth Lake and the Anglo Rouyn deposits (Forsythe, 1971, 1976). The mafic rocks are engulfed by extensive tonalitic-granodioritic plutons. The eastern part of the Bob Lake area is underlain by sedimentary gneisses that show continuity into the Hickson Lake area to the north (Crew Lake assemblage of MacLachlan, 2005). They can also be traced southeastward, where greywackes are exposed in an antiform that crosses Highway 102 (Thomas, 1986). These sedimentary rocks of the former ‘Crew Lake belt’ are considered to represent a lower metamorphic–grade component of the Rottenstone Domain (Saskatchewan Geological Survey, 2003).
No absolute age constraints exist for the rocks at Bob Lake and Nemeiben Lake, other than the regional ones discussed in the previous report (Maxeiner and MacLachlan, 2010). Based on those few regional time markers, the mafic volcanoplutonic succession is speculated to be older than 1.87 Ga, while the intruding tonalite-granodiorite bodies are assumed to be circa 1.85 Ga, a common age for subduction-related granitoids in the Reindeer Zone, although some may represent considerably younger anatectic melts.
4. Description of Main Units 1 a) Supracrustal Rocks Supracrustal rocks in the Bob-Miles lakes area comprise two main types, mafic volcanic rocks and clastic sedimentary rocks, and are assumed to represent the oldest geological component of the area. Based on work at Nemeiben Lake (Maxeiner and MacLachlan, 2010), the relative age of the mafic volcanic rocks with respect to the clastic sedimentary rocks is speculative, as the contact between the two is represented by high-strain zones. In this
1 Description of plutonic and metasedimentary rocks follows the IUGS classification of igneous rocks (Streckeisen, 1976) and an ‘in-house’ classification of metamorphosed clastic sedimentary rocks (Maxeiner et al., 1999), respectively. A ‘metamorphic colour index’, based on the percentage of mafic minerals in a metamorphosed rock, was used in the field to distinguish between mafic (>35), intermediate (35 to 15), and felsic (<15) variants of volcanic and plutonic rocks. As all of the rocks in the Bob Lake area have been metamorphosed under middle to upper amphibolite facies conditions, the prefix “meta-“ is dropped in the discussion of rock types.
Saskatchewan Geological Survey 5 Summary of Investigations 2011, Volume 2 report we describe the volcanic rocks first, as they appear to be structurally at the lowest level although A they are not necessarily the oldest rocks. Mafic volcanic rocks (unit Mv) are exposed in an 800 m wide 2 unit between McGuigan Lake and the north shore of Ball Lake, where they continue southwestward towards the central part of Nemeiben Lake (Figure 2). A second and likely fold-repeated unit is exposed west of Miles Lake (Figure 1), from where it continues south- and then eastward towards Highway 102. On the regional map (Figure 1), both these units converge northward. Generally, these non-magnetic rocks are homogeneous, although decimetre- to metre- scale layering was observed in some outcrops (Figure 3A). Layering is defined by variations in mafic content and/or grain size; intermediate volcanic rocks and calc- silicate layers represent a minor constituent. The rocks are generally fine grained consisting of roughly equal proportions of hornblende and plagioclase, with local concentrations of diopside, titanite, epidote, and rare B garnet. The rocks are locally strongly foliated and sheared. Gradational contacts with ferruginous psammite and siliceous rusty rocks were observed in a number of places. Many exposures of mafic volcanic rocks contain metre-scale transposed and strongly foliated to sheared gabbro layers, as well as centimetre- to decimetre-scale tonalitic to granodioritic dykes (Figure 3A), which are locally isoclinally folded. Mafic volcanic rocks are interpreted to have been derived from volcanic flows that contain minor tuffaceous horizons and subvolcanic intrusions.
A variant of the mafic volcanic rocks are layered mafic calc-silicate rocks (unit Mvc), which form the core of the Bob Lake structural dome (Figure 2). Flaggy layering in these rocks is tectonic in nature, as it is produced by transposition of originally irregular zones of calc-silicate alteration and possible pillow selvedges. C The resulting rock is characterized by pale green diopside-rich layers alternating with greenish black amphibolite layers to generate a very distinct outcrop appearance (Figure 3B). The calc-silicate rocks are strongly foliated to locally mylonitic and intruded by somewhat less-deformed metre-scale gabbroic (Figure 3C) and abundant outcrop-scale granodiorite sheets (unit T), as well as later straight-walled granite pegmatite. They likely represent highly strained versions of originally pillowed mafic volcanic flows. On a map scale, the unit is interleaved with leucogranodiorite and granodiorite (Figure 2), which are also locally strongly foliated to mylonitic, particularly where observed in contact with the calc- silicate rocks. Figure 3 – A) Layered mafic to intermediate volcanic rock Sedimentary rocks have been differentiated into three with granodiorite dykelets; note bedding surface (dashed units, of which a unit of calcic psammopelite- arrow) and isoclinally folded granodiorite dykelet (solid psammite (unit Pcs) is closely associated with the arrow); station RM11-12-ST19 northwest of Ball Lake; mafic calc-silicate rocks in the core of the Bob Lake UTM 489653 m E, 6148251 m N; B) tectonically layered structural dome (Figure 2). The unit is characterized by mafic calc-silicate rocks, likely derived from mafic volcanic flows by transposition of originally irregular zones of calc- silicate alteration (solid arrows) and possible pillow selvedges; station RM11-15-ST24 west of Bob Lake; UTM 2 ‘Width’ refers to the surface expression of the unit and does not 490019 m E, 6145783 m N; and C) decimetre-scale represent its true thickness. transposed gabbroic layer (solid line) within mafic calc- silicate rocks; same station as B). All UTMs are in NAD 83, zone 13 unless otherwise stated.
Saskatchewan Geological Survey 6 Summary of Investigations 2011, Volume 2 flaggy rocks (Figure 4A) of strong compositional variability. In addition to hornblende-bearing A quartzofeldspathic rocks, there are some intermediate and mafic (?)tuffaceous layers, as well as biotite-rich pelitic layers. Partial melt is present, although it appears to be injected rather than in situ (Figure 4B). Minor and variable amounts of carbonate, diopside, garnet, graphite, and titanite are also present. The unit is structurally sandwiched between the layered mafic calc-silicate rocks and overlying, highly strained and silicified tonalite. A unit of clastic sedimentary rocks structurally overlies the mafic calc-silicate rocks on the southeast side of Bob Lake, as well as in narrow discontinuous layers within the surrounding tonalite intrusions (Figure 2). Psammite (-psammopelite) (unit Ps) is a unit of generally poorly exposed fine-grained quartzofeldspathic rocks, which locally exhibit rusty weathering as a result of ferruginous psammite layers containing minor concentrations of disseminated B pyrrhotite. Where decametre-scale units of these rocks are entrained by tonalite (unit T) they ‘contaminate’ the younger plutonic rocks and consequently also create rusty weathering outcrops. The psammitic rocks are layered on a centimetre- to decimetre-scale and are well foliated to locally gneissic. Where the rocks are more psammopelitic in composition, they may contain in situ granodioritic leucosome. Biotite is ubiquitous, with local concentrations of muscovite. Drill core of the unit on the west side of Bob Lake also contained locally sillimanite-bearing psammopelitic intervals.
The most extensive of the sedimentary units is migmatitic psammopelite (-psammite) (unit Psp), occurring in a >1 km wide belt east of Miles Lake (Figure 2) from where it continues south toward Highway 102 and north towards the Churchill River (Figure 1). The psammopelite occurs structurally above C the Miles Lake mafic volcanic unit and is considered a component of the Crew Lake assemblage, most recently described as the easternmost lowest-grade component of the central Rottenstone Domain (MacLachlan, 2005). In outcrop, the psammopelite weathers grey to brownish grey and is fine to medium grained. The well-foliated to gneissic rocks are typically compositionally layered on a centimetre to decimetre scale, with psammopelitic layers predominating over minor psammitic layers. In situ granitic leucosome is variably developed, commonly accounting for 10 to 20% of most outcrops (Figure 4C). These quartzofeldspathic rocks contain ubiquitous K- feldspar and muscovite, resulting in relatively high potassium concentrations. Other minerals include abundant biotite, as well as scarce graphite and Figure 4 – A) Flaggy weathering, bedded calcic sillimanite. psammopelite from station RM11-15-ST13 north of Bob Lake; UTM 490712 m E, 6146136 m N; B) injected b) Intrusive Rocks leucosome into layered psammopelite; station RM11-15- ST14 north of Bob Lake; UTM 490786 m E, 6146196 m N; Similar to the Nemeiben Lake area (Maxeiner and and C) in situ melting in migmatitic muscovite-bearing MacLachlan, 2010), the Bob-Miles lakes area is psammopelite of the Crew Lake assemblage-type dominated by extensive tonalitic-granodioritic plutons. sedimentary succession; station RM11-19-ST18 northwest of The contacts between most of the granitoid units are Miles Lake; UTM 494332 m E, 6149136 m N. gradational, suggesting contemporaneous emplacement.
Saskatchewan Geological Survey 7 Summary of Investigations 2011, Volume 2 Diorite and gabbro intrude the mafic volcanic rocks but are themselves intruded by the granitoids, and an oval- A shaped intrusion of monzodioritic composition intrudes the sedimentary rocks east of Miles Lake. Gabbroic rocks are a common component of the mafic volcanic unit, where they occur as metre-scale sills. Where these sills become more extensive, gabbro (unit Ga) forms discrete map-scale units. The gabbroic rocks are moderately to strongly foliated, commonly containing transposed tonalitic to granodioritic sheets. Most of the gabbros have relatively simple mineralogy consisting of equal proportions of medium-grained hornblende and plagioclase. Locally, they are characterized by diopside and minor titanite, as well as by thin, irregular carbonate veins. Fine- to medium-grained sheared diorite/microdiorite (unit Di) forms a number of 10- to 100-m scale map units southwest of Ball Lake, where they are closely B associated with the gabbroic rocks and also intrude the mafic volcanic rocks. Commonly these rocks are fine grained and equigranular and could therefore also be interpreted as being of volcanic origin. They are cut by granodiorite dykes (Figure 5A). Because of their overall homogeneous appearance, the observed gradational change into more typical medium-grained dioritic rocks, and their close association with gabbros, they are believed to represent fine-grained intrusive rocks.
Two (?)refolded units of hornblende granodiorite/ leucogranodiorite (unit Gdh) are exposed south of Ball Lake and another is located 1.5 km east of Bob Lake (Figure 2). These light grey to pinkish brownish grey, medium-grained rocks are distinguished from other granitoid intrusions of the area by containing up to 10% hornblende, as well as transposed layers of older diorite and inclusions of amphibolite. The rocks C are typically well foliated to gneissic and commonly are cut by less deformed, porphyritic granodiorite dykes and sheets of tonalite/granodiorite. Because of their gneissic character and presence of crosscutting biotite tonalite-granodiorite, these hornblende granodiorite units south of Ball Lake may be part of an older granitoid suite. An approximately 400 m wide and several kilometre long unit of granodiorite/leucogranodiorite gneiss (unit Gdm) extends from the southern half of Miles Lake southward (Figure 2). These light to pinkish grey, medium-grained rocks are strongly foliated to locally mylonitized. Mylonitic zones within this unit are finer grained and silicified. For the most part, the rocks are leucocratic and commonly magnetite bearing, although Figure 5 – A) Transposed granodiorite dykes cutting the magnetite has locally been hematized. In the central strongly foliated microdiorite; station RM11-14-ST18 near part of the unit, the leucogranodiorite gives way to a southwest Ball Lake; UTM 487723 m E, 6145744 m N; hornblende-magnetite–rich granodiorite. B) angular xenoliths of amphibolite derived from gabbro within coarse-grained, weakly foliated quartz-phyric One of the most widespread units of the Bob-Miles granodiorite; station RM11-09-ST17 at southwest Ball Lake; lakes area is biotite tonalite-granodiorite UTM 488328 m E, 6145831 m N; and C) close-up view of a quartz-phyric granodiorite with large clots of biotite (-leucogranodiorite), with one unit centred on Bob (arrows); station RM11-17-ST24 north of Sharpe Lake; Lake and structurally overlying the mafic calc-silicate UTM 493612 m E, 6144960 m N. rock (unit Mvc) and another unit occurring west of
Saskatchewan Geological Survey 8 Summary of Investigations 2011, Volume 2 McGuigan Lake (Figure 2). Biotite tonalite-granodiorite is white, light grey to light pinkish grey, medium to coarse grained, and massive to moderately foliated. It is generally homogeneous, locally containing screens and xenoliths of units Mv and Mvc. Biotite is generally the sole mafic mineral and accounts for up to 10% of the rock, although rarely exceeds 5%. As a subunit of the biotite tonalite-granodiorite, leucocratic felsic gneiss (unit Tgl) essentially represents a strongly foliated to mylonitic equivalent. It tends to occur where the tonalite-granodiorite pluton is in contact with sulphide-bearing varieties of the psammite (-psammopelite). The tonalite-granodiorite is younger than the supracrustal rocks and partially assimilated the ferruginous sedimentary rocks during emplacement. A unit of quartz-phyric granodiorite (-leucogranodiorite) (unit Gdq) has gradational contacts with the biotite tonalite-granodiorite, which it surrounds and structurally overlies (Figure 2). These rocks also contain xenoliths of mafic volcanic rocks and gabbro (Figure 5B). The light pink to pinkish grey rocks are medium to coarse grained with local gradational changes into granitic pegmatite. They are distinguished from the biotite tonalite-granodiorite by irregular centimetre-scale aggregates of quartz and biotite (Figure 5C). The homogeneous rocks are generally massive to moderately foliated, commonly carrying one of the younger (?S3) north-striking foliations. A north-trending, 1 x 5 km long, ovoid intrusion of monzodiorite (diorite, quartz-diorite) (unit Mdi) is located east of Miles Lake, where it intrudes migmatitic psammopelitic sedimentary rocks. It is very similar in composition and appearance to monzodioritic rocks mapped south of Nemeiben Lake (Maxeiner and MacLachlan, 2010), which were interpreted to have been emplaced after F1/F2 folding of the Crew Lake assemblage sedimentary rocks, but prior to D3 deformation. The Miles Lake monzodiorite is medium to coarse grained, equigranular and generally massive to weakly foliated carrying only a north-striking S3 fabric. The pluton commonly contains abundant xenoliths of migmatitic psammopelite (unit Psp) and is itself cut by granitic pegmatite (unit P). In addition to plagioclase, hornblende (10 to 20%), and K-feldspar (5 to 15%), the rock contains minor amounts of biotite and quartz. Spectrometric analysis suggests concentration of about 1.5 to 2.0% K.
Granite pegmatite, leucogranite (Unit P) represents the latest igneous activity, cutting all other granitoid rocks. It is generally massive to weakly foliated, containing large books of biotite and local garnet.
5. Structural Geology and Metamorphism a) Primary Features Primary features are not generally well preserved in the Bob-Miles lakes area because of upper amphibolite facies metamorphism and the high state of strain. In addition, recognition is further prevented by a general lack of good- quality bedrock exposures on supracrustal rocks. Within the mafic volcanic rocks, possible relict pillows have been observed in only a couple of exposures. Similarly, the sedimentary rocks exhibit primary features in the form of compositional layering in only a few outcrops. All these S0 features have been affected by subsequent deformation and are transposed parallel to the main regional S1 and S2 fabrics. No facing directions were discerned from the primary features. b) First- and Second-generation Structures Building on work from the Nemeiben Lake area (Maxeiner and MacLachlan, 2010), first-generation structures include layer-parallel S1 foliations defined by mica in the sedimentary rocks and by amphibole in the volcanic rocks. Outcrop-scale F2 folding of this S1 foliation was only observed in a handful of exposures and is mostly restricted to the supracrustal rocks. Most of these folds are close to isoclinal and deform transposed calc-silicate layering in the mafic volcanic rocks and bedding-parallel leucosome and S1 foliation in the sedimentary rocks. The majority of the axial planes of these F2 structures are west to northwest dipping, locally carrying a weak axial planar fabric. The hornblende granodiorite (unit Gdh) exposed south of Ball Lake may represent an older suite of granitoids, as its gneissic layering is folded by variably oriented tight folds (F2) and is cut by porphyritic granodiorite dykes (Figure 6) that only carry a weak foliation (likely S3). The gneissosity is therefore interpreted as an S1 fabric, which appears to be generally absent from the rest of the Bob Lake granodiorites (units T and Gdq). This suggests that two suites of granodiorite exist in the Bob Lake area. The vast majority of tonalite-granodiorite rocks belong to the younger suite (units T and Gdq) and generally only carry one tectonic fabric, which is defined by biotite and flattening of feldspar and quartz. This main tectonic fabric in the biotite tonalite-granodiorite is assumed to be an S2 fabric. In a number of areas, particularly on the west side of Ball Lake, two fabrics are developed in the granodiorite (unit Gdq). They are oriented at an acute angle to each other and likely represent S2 and S3, rather than S1 and S2 since the same granodiorite cuts the S1 fabric in dioritic rocks.
Saskatchewan Geological Survey 9 Summary of Investigations 2011, Volume 2 In outcrops where small transposed granodiorite dykes are cutting mafic volcanic rocks or older granitoid gneisses, the dykes carry a weak northwest-dipping second foliation that is at an angle to the foliation preserved in the country rock and that likely represents an S3 fabric.
c) Bob Lake Structural Dome Map-scale folds are more prevalent then outcrop-scale folds in the map area. The Bob Lake structural dome, defined by doubly folded units of mafic calc-silicate rocks and interlayered transposed tonalitic sheets (Figure 2), is likely the result of fold interference between north-northeast–trending F3 structures and a superimposed northeast-trending F4 antiform (Figure 2). A subvertical to steeply west-dipping foliation is well developed in some of the tonalite-granodiorite Figure 6 – Feldspar-porphyritic granodiorite dyke bodies north of Bob Lake, particularly in the coarse- (enhanced by yellow dashed lines) cutting gneissic hornblende granodiorite with S1 gneissosity (white dashed grained quartz-rich granodiorite (unit Gdq), and is line); RM11-04-ST09 south of Ball Lake; UTM 487852 m E, interpreted as having developed axial planar to the F3 6144461 m N. folds. A weak, steeply west- to west-northwest–dipping tectonic foliation was also measured in the monzodiorite east of Miles Lake and is also interpreted to have developed synchronous with D3 deformation. The inferred relative age of the foliation is based on observations made during the 2010 field season in the Nemeiben Lake area, where the monzodiorite contains folded xenoliths of psammitic to psammopelitic rocks. Monzodiorite emplacement post-dated development of the F2 outcrop-scale structures (Maxeiner and MacLachlan, 2010).
Slight variations in azimuth and dip direction of S3 in the Bob Lake area are in turn a result of refolding by northeast-trending regional F4 folds (Lewry et al., 1990). d) Shear Zones Apart from isolated areas of small-scale shear zones, two continuous zones of high strain have been identified. The Miles Lake shear zone extends along the length of Miles Lake, where it follows the contact between a mafic volcanic unit and Crew Lake assemblage sedimentary rocks to the east. The shear zone is moderately east dipping and has a variably well-developed, moderately to steeply plunging, north-plunging stretching lineation (?D2), but shear sense indicators are not developed.
A second high-strain zone exists in the centre of the Bob Lake dome. Mafic calc-silicate gneiss, representing highly strained equivalents of mafic volcanic rocks, is in structural contact with highly strained granodiorite and psammite, which structurally overlie the mafic rocks. No stretching lineation is preserved in these rocks, but the interpretation is that the granodiorite and psammite have been thrust over the mafic rocks and that two thrust slices repeat the same sequence. Some of the highly strained granitoids in the Bob Lake structural dome have previously been misinterpreted as sedimentary in origin (Forsythe, 1971). Mineral and stretching lineations measured northwest of Ball Lake, where mafic volcanic rocks are intruded but also structurally overlain by tonalite-granodiorite, are moderately northwest plunging. No distinct high-strain zone was identified in that area, but small shear zones were observed in a number of places. Since this package of rocks and the small shear zones are situated in the same lithostructural position as the Miles Lake high-strain zone, they likely pre-date formation of the north-trending Bob Lake F3 antiform, as they occur on the opposite limb of the fold and are apparently folded by it. e) Metamorphism An amphibolite-facies assemblage of hornblende-plagioclase-diopside is preserved in all the mafic volcanic rocks. Sedimentary rocks east of Miles Lake are characterized by the assemblage K-feldspar–quartz–biotite–muscovite, yet they also contain what appears to be locally derived granitic leucosome. Appearance of partial melt in psammopelitic to pelitic rocks is generally attributed to the reaction that produces sillimanite and K-feldspar (e.g., Yardley, 1989). At Miles Lake, no sillimanite has been observed, although sillimanite is present in drill core that intersected psammitic rocks on the southwest side of Bob Lake. Consequently, it is believed that metamorphic conditions in the Miles-Bob lakes area were at the transition from middle to upper amphibolite facies. Sillimanite in
Saskatchewan Geological Survey 10 Summary of Investigations 2011, Volume 2 drill core appears to be overprinted by retrograde muscovite. These observations are in agreement with A metamorphic conditions reported for the Nemeiben Lake area to the south (Maxeiner and MacLachlan, 2010).
6. Discussion of Economic Potential The exploration history of the Bob Lake area is briefly summarized in the introduction. During the course of field work, some of the drill holes completed by MacDonald Mines were examined. As this work remains confidential, only a few general comments in regards to styles of mineralization and interpretation of host rocks are given here, with permission of the company. The diamond-drill holes that were examined are scattered over a 10 km x 4 km, northeast-trending tract between north Nemeiben Lake and Bob Lake. B Based on field mapping and drill-core observations, the bulk of the mineralization between Bob and Nemeiben lakes is hosted by mafic volcanic rocks, with lesser intermediate to mafic plutonic-hosted and minor sediment-hosted mineralization. The sulphides range from disseminated to massive in texture and are dominated by pyrrhotite, with minor amounts of chalcopyrite and pyrite. A few more detailed observations, given under the headings of the presumed style of mineralization present, are presented below. a) Volcanogenic Massive Sulphide Potential Several of the diamond-drill holes intersected 10-m scale, disseminated to metre-scale semi-massive sulphide mineralization, which was dominated by pyrrhotite with minor amounts of chalcopyrite and hosted by fine-grained mafic volcanic rocks and mafic calc-silicate rocks. Some of the mafic volcanic rocks C are characterized by trachytic textures, as described from the Nemeiben Lake area (Maxeiner and MacLachlan, 2010), with millimetre-scale elongated plagioclase phenocrysts contained in a fine-grained hornblende-plagioclase matrix. The phenocrysts have been recrystallized to fine-grained multi-grain aggregates. Locally, the trachytic mafic volcanic rocks are accompanied by garnet porphyroblasts, which have been variably affected by decompression, causing the garnets to break down to a mixture of plagioclase, quartz, and biotite that is preserved in symplectic coronae (Figure 7A). The relatively high garnet content of the mafic volcanic rocks observed in some of the drill core and in the Nemeiben Lake area (Maxeiner and MacLachlan, 2010) is likely related to regional alteration related to syngenetic hydrothermal activity. Figure 7 – MacDonald Mines’ diamond-drill core from Garnets were not seen to be accompanied by holes in the larger Bob Lake area; locations remain cummingtonite or anthophyllite, nor were cordierite- confidential. A) Decompressed garnets (solid arrows) anthophyllite assemblages observed; such middle to defining a second foliation, which overprints S1 (dashed upper amphibolite facies metamorphic assemblages are arrow); B) folded millimetre- to centimetre-scale generally accepted as representing the more intensely (?)cumulate layering defined by sulphides and igneous mafic altered proximal zones of volcanogenic massive minerals in gabbro; and C) muscovite-bearing psammitic to sulphide deposits. They have been noted along strike of psammopelitic gneisses with minor disseminated pyrrhotite. the Cu-rich Elizabeth Lake deposit (Maxeiner and
Saskatchewan Geological Survey 11 Summary of Investigations 2011, Volume 2 MacLachlan, 2010) and in some of the historic drill holes that intersected the deposit (SMER Assessment File 73P06-SW-0149). Regional map patterns and the observed lithostructural relationships suggest that the mafic volcanic and calc-silicate rocks at Bob Lake and Miles Lake are part of the same successions of variably strained mafic volcanic-gabbroic rocks that host the Elizabeth Lake deposit on Nemeiben Lake and the Anglo Rouyn deposit at Waden Bay of Lac La Ronge (Roberts and Maxeiner, 1999) (Figure 1), and the Pitching Lake deposit west of Trade Lake (Maxeiner and Normand, 2009). b) Magmatic Cu-Ni Potential A few of the diamond-drill holes intersected tens of metres of dioritic to gabbroic rocks that contain disseminated, semi-massive, and massive pyrrhotite-dominated sulphide mineralization (Figure 7B). The gabbroic rocks hosting layered semi-massive sulphides show relict igneous pyroxene crystals with interstitial pyrrhotite in thin section, suggesting that the mineralization is magmatic in origin. Most of the pyroxene has been variably amphibolitized to hornblende and/or actinolite. Some of the highest sulphide concentrations in one of the diamond-drill holes are at the contact between gabbro and garnet-biotite-graphite–bearing psammopelitic rocks in the footwall. The sedimentary rocks contain minor quantities of disseminated pyrrhotite, likely primary in origin, but also contain replacement veins of massive chunky pyrrhotite, probably representing partially remobilized sulphide. Networks of calc-silicate veins are also widespread, as are relatively late veins containing carbonate, actinolite, and chloritoid. As observed in the field, the gabbros appear to intrude a mafic volcanic succession, but are themselves cut by abundant biotite tonalite to granodiorite. Magmatic hosted Cu-Ni deposits are known from the Nemeiben Lake area, where ultramafic rocks hosting the Dunlop Deposit (MacFarlane and Mossman, 1982) are believed to post-date both the voluminous granitoid plutons of the area (Maxeiner and MacLachlan, 2010) and the gabbroic rocks intruding the mafic volcanic rocks. This suggests that there are two generations of mafic-ultramafic intrusions in the Nemeiben-Bob lakes area. c) Sediment-hosted Sulphides The sedimentary succession exposed southeast of Bob Lake and on the peninsula on the north side of the lake, is in part characterized by minor ferruginous psammite layers containing disseminated iron sulphides. Locally, these ferruginous psammites, which are in part graphite-bearing, are contained as thin slivers within the younger tonalite- granodiorite bodies. Near the margin, which is generally highly strained, the granodiorite commonly exhibits rusty weathering due to assimilation of some of the sedimentary rocks.
One of the examined diamond-drill holes transects a sequence of these ferruginous psammitic to psammopelitic sedimentary rocks containing up to 10% disseminated pyrrhotite and pyrite (Figure 7C). The sedimentary succession is about 100 m in thickness and occurs as a giant raft in biotite tonalite-granodiorite on the southwest side of Bob Lake. The fine-grained quartzofeldspathic rocks are mostly psammopelitic in composition with garnet, biotite, muscovite, and minor graphite, as well as sillimanite in a more pelitic component. Examples of granitic partial melt exist locally and can be distinguished from metre-scale dykes of younger leucogranodiorite.
These sedimentary rocks could have originated as sulphidic sandstones and their age relative to the mafic volcanic- gabbroic succession remains speculative. Based on the work at Nemeiben Lake (Maxeiner and MacLachlan, 2010) and some of the outcrop and drill-hole observations made this summer, a stratigraphic transition from mafic volcanic rocks, through calcic psammopelite with intermediate to mafic tuffs, into biotite-muscovite–bearing psammite is suggested. The immediate contact zone is, however, also invariably accompanied by high-strain zones. The timing of deposition of these sedimentary rocks relative to intrusion of the older gabbroic suite has important implications for mineral exploration. If they are older, they would have been an excellent source of crustal sulphur, an important ingredient in the formation of magmatic-hosted Cu-Ni mineralization (e.g., Keays and Lightfoot, 2009). A similar succession of sedimentary rocks in contact with a mafic volcanoplutonic succession was also mapped in the Hebden-Freestone lakes area (Maxeiner and Kamber, this volume) and may represent the fold- repeated equivalent of the Bob Lake area. There, the gabbroic rocks appear to intrude the sedimentary succession. Geochronological studies will shed further light on this relationship.
7. Preliminary Conclusions 1) Supracrustal rocks in the core of the Bob Lake structural dome are derived from highly strained mafic volcanic rocks that are structurally overlain by muscovite-bearing psammitic-psammopelitic rocks. It is unclear whether stratigraphic continuity existed between the two units prior to shearing.
Saskatchewan Geological Survey 12 Summary of Investigations 2011, Volume 2 2) Migmatitic psammopelite east of Miles Lake is part of the Crew Lake assemblage of the Rottenstone Domain and is macroscopically indistinguishable from the sedimentary rocks along the Nemeiben Lake road (Maxeiner and MacLachlan, 2010). Similarly, a monzodiorite intrusion in these sedimentary rocks east of Miles Lake is the same generation as a pluton south of the Nemeiben Lake road. 3) There are possibly two tonalite-granodiorite suites of disparate ages: older hornblende-bearing granodiorite gneisses exposed southwest of Bob Lake and younger biotite tonalite-granodiorite representing the bulk of the granitoid intrusions. 4) The Bob Lake region has the potential to host volcanogenic massive sulphide mineralization and gabbro-hosted Cu-Ni mineralization, particularly where gabbros are in contact with pyrrhotite-pyrite–bearing sedimentary successions. 5) The Pitching Lake, Anglo Rouyn, Elizabeth Lake, and some of the Bob Lake massive sulphide occurrences are all hosted by a contemporaneous mafic volcanoplutonic succession. This succession occurs near the boundary with a structurally overlying muscovite-bearing psammitic-psammopelitic sedimentary succession.
8. Acknowledgements Geological assistants Lynde Guillaume and Megan Lefaivre are thanked for their cheerful and capable field assistance. Bill Layman and Lynda Holland are thanked for their hospitality and home-cooked meals while we were staying on their property at Bob Lake. MacDonald Mines Ltd. is thanked for granting permission to look at the drill core from their 2009 drilling program. Pilots and support staff from Osprey Wings, as well as owner Gary Thompson, are thanked for providing excellent air support and being accommodating and flexible with ever- changing schedules. We appreciated the reliability of Leo and Sherry Jacobsen of Churchill River Trading Post, who provided us with quality food and supplies for the duration of the field work. Ryan Morelli and Ken Ashton are thanked for thoroughly reviewing an earlier version of the manuscript.
9. References Ashton, K.E. (1999): A proposed lithotectonic domainal re-classification of the southeastern Reindeer Zone in Saskatchewan; in Summary of Investigations 1999, Volume 1, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 99-4.1, p92-100.
Forsythe, L.H. (1971): The Geology of the Nemeiben Lake Area (East Half) and the Geology of Mineral Deposits in the Nemeiben Lake–Stanley Areas, Saskatchewan, Sask. Dep. Miner. Resour., Rep. 115, pt2, 178p.
______(1976): The Geology of the Nemeiben Lake Area (West Half) and the La Ronge Area (West Half), Saskatchewan, Sask. Dep. Miner. Resour., Rep. 152, 18p.
Keays, R.R. and Lightfoot, P.C. (2009): Crustal sulfur is required to form magmatic Ni-Cu sulphide deposits: evidence from chalcophile element signatures of Siberian and Deccan Trap basalts; Mineral. Dep., v45, p241- 257.
Lewry, J.F., Thomas, D.J., Macdonald, R., and Chiarenzelli, J. (1990): Structural relations in accreted terranes of the Trans-Hudson Orogen, Saskatchewan: telescoping in a collisional regime?; in Lewry, J.F. and Stauffer, M.R. (eds.), The Early Proterozoic Trans-Hudson Orogen of North America, Geol. Assoc. Can., Spec. Pap. 37, p75-94. Macdonald, R. (1987): Update on the Precambrian geology and domainal classification of northern Saskatchewan; in Summary of Investigations 1987, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 87-4, p87-104. MacFarlane, N.D. and Mossman, D.J. (1982): Geology of the Nemeiben Lake ultramafic complex, north-central Saskatchewan; CIM Bull., v75, no837, p83-91. MacLachlan, K. (2005): A tale of two transects: distribution of 2.38 to 2.55 Ga versus juvenile 1.89 to 1.86 Ga detritus in the Rottenstone Domain; in Summary of Investigations 2005, Volume 2, Saskatchewan Geological Survey, Sask. Industry Resources, Misc. Rep. 2005-4.2, Paper A-7, 19p. Maxeiner, R.O., Gilboy, C.F., and Yeo, G.M. (1999): Classification of metamorphosed clastic sedimentary rocks: a proposal; in Summary of Investigations 1999, Volume 1, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 99-4.1, p89-92.
Saskatchewan Geological Survey 13 Summary of Investigations 2011, Volume 2 Maxeiner, R.O. and MacLachlan, K. (2010): Preliminary bedrock geology of the eastern Nemeiben Lake area in the vicinity of the Elizabeth Lake Cu deposit and the Dunlop Cu-Ni deposit, western Glennie Domain (parts of NTS 73P/03, /06, and /07); in Summary of Investigations 2010, Volume 2, Saskatchewan Geological Survey, Saskatchewan Ministry of Energy and Resources, Misc. Rep. 2010-4.2, CD-ROM, Paper A-7, 17p, URL
Thomas, M.W. (1986): Bedrock geological mapping, MacKay Lake south (part of NTS 73P-7W); in Summary of Investigations 1986, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 86-4, p54-62.
Saskatchewan Geological Survey (2003): Geology, and Mineral and Petroleum Resources of Saskatchewan; Sask. Industry and Resources, Misc. Rep. 2003-7, 173p.
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Yardley, B.W.D. (1989): An Introduction to Metamorphic Petrology; Longman, Singapore, 248p.
Saskatchewan Geological Survey 14 Summary of Investigations 2011, Volume 2