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Home , Phonolite

o eol gic g a a l

b s u Drillcore observations from the south Wekusko Lake area, eastern Flin Flon belt, o

t r

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m north-central Manitoba 1928 K.D. Reid and S. Gagné

EPV-9-94 EPV-14-94 EPV-8-94 Rock type Volcanic facies SL91-3 SL91-4 138-15 138-17 138-18 B-73 CP-11-008 CP-11-014 WEK-94-3A EPV-12A W-13 218-10 138-26 138-27 138-24

Missing core Amydaloidal Drillcore observations Phanerozoic cover Pillowed flows Introduction Regolith 430 000 440 000 450 000

Mafic 200 m JT MV Crystal tuff

B 200 m During a two-week period in the summer of 2016 a total of 18 WT Intermediate 200 m S P Monolithic lapilli tuff WT P Wekusko lt Heterolithic lapilli tuff drillholes were examined and sampled in an effort to further a P s Gabbro/diorite a Lake Puella b B Heterolithic tuff breccia r e B Bay e k u Chlorite schist Snow iv r understand the highly prospective sub-Phanerozoic extension of a n Alteration Lake R L ( tw Intrusive breccia s g ( o Chlorite±carbonate s in Goose o assemblage a d Schist-Wekusko the Flin Flon belt directly south of Wekusko Lake. This work r p Bay g G m ( ( r assemblage Mudstone Sericite±chlorite±silica P ra o T Hayward Creek u J p Sandstone, wacke t M l assemblage Mineralization provides critical new data to constrain exploration models for u PU a f Disseminated sulphide

P k ( Rock textures

t Broad e l

re J Wekusko Lake u Bay a -phyric

VMS deposits in this geologically complex and challenging area. C f Semisolid sulphide

6 060 000 y 6 060 000 and y rr Broad S WT e a B Alward Lake SW Wekusko B Bay (

k B pluton pluton c pluton Tramping J u d

Lake EPV-8-94 w o

r M ( P EPV-9-94 The objectives of this season's fieldwork were to 1) document the C F P EPV-14-94 EPV-12A-94 !.!.!.

volcanic facies and alteration associated with the Copper-Man P *#( !. a b !. 138-15 Copper-Man South Wekusko deposit and rocks south of Wekusko Lake; 2) obtain additional assemblage

138-17 !. CP-11-006 WT a b a b whole-rock geochemical data for an area not covered by previous !.!. 138-18 P a k Cree SL91-4 !. !. SL91-3 F PU regional compilations; and 3) identify the extent, depositional B rd a 6 050 000 P w !. 6 050 000 ay B-73 facies and metamorphic grade of sedimentary rocks, interpreted H W as Burntwood group turbidites and Missi group sandstone and !. CP-11-008 J P

conglomerate, that extend south from Wekusko Lake, in order to !.WEK-94-3A c d Farwell !. Clearwater W-13 b c Lake understand the complex tectonostratigraphy of the area. B Domain 138-27 400 000 425 000 450 000 475 000 500 000 !. c d c d M P B 6 125 000 6 125 000 P East 218-10!. 6 040 000 6 040 000 Kisseynew Wimapedi Kisseynew r domain Lake ve Ri F Domain to !. 138-26 ish Kofman Mit *# 138-24!. P e f

r P d e e v i R !. CP-11-014

6 100 000 6 100 000 J e f e P B Osborne Hargrave Loonhead s Squall Bur s Lake a Lake Lake *# r Lake *# G *#Lon SLA Lalor Anderson Lake File P Cook Lake Stall Lake P P Lake 6 030 000 6 030 000 *# Photo Pen ## *#Dickstone *# *#lake *# *#Rod Chisel North *# *#*# Sylvia J FIA *#*#Ghost/Lost *#Linda *# P B Chisel open pit Lake Ram Sedimentary and plutonic rocks from south Wekusko P Raindrop Wekusko 6 075 000 *# MV 6 075 000 P Morgan Lake Lake area: a) sharp contact between pebbly sandstone Pot lake r e Lake *# v Watts 430 000 440 000 450 000 Rail *# i M # *# R River * with quartz and lithic grains (left arrow) and s s ra SWA Scale 1:250 000 G SUCCESSOR-BASIN DEPOSITS SUCCESSOR-ARC PLUTONS 0 5 Volcanic rocks of the Copper-Man deposit: a) heterolithic tuff Volcanic rocks from the south Wekusko Lake area: types from the south Wekusko Lake area: garnet/staurolite–bearing mudstone beds (right arrow), SLA km HCA M Missi group P Intrusive rocks breccia showing quartz-phyric dacitic fragments and mafic a) mafic -crystal tuff, SL91-3, 60.4 m; b) mafic a) quartz-phyric with mafic lapilli, CP-11-008, 192 EPV-12A, 112.5 m; b) pebbly sandstone bed with well- Reed MV Missi group volcanic rocks PU Ultramafic rocks Phanerozoic boundary edge Fourmile fragments of various compositions in a fine-grained, green lapilli tuff that is pervasively chlorite altered and contains m; b) heterolithic tuff breccia with chloritized matrix, CP- Island *# *# B Burntwood group JUVENILE ARC Domain boundary developed basal scour into underlying mudstone (left Lake Copper Man –phyric tuff matrix, EVP-9-94, 349 m; b) silicified, 'pinhead' garnets in the matrix (arrows show flattened 11-008, 262.5 m; c) bedded feldspathic wacke (arrows S Schist-Wekusko assemblage J Juvenile-arc rocks Fault arrow) and mudstone rip-up clasts (right arrow), W-13, Reed ## *# Farwell W Rocks of uncertain age JT Synvolcanic to granodiorite, ( Thrust fault shard-like, felsic lapilli fragments (arrow) in a green-grey tuff lapilli), SL91-3, 98.8 m; c) clast-supported breccia with show two fining sequences), CP-11-008, 290.7 m; d) 6 050 000 Spruce 6 050 000 167.6 m; c) andalusite porphyroblasts in dark grey point Lake WT Tectonite, phyllonite, mylonite OCEAN FLOOR !. Diamond-drill hole matrix, EVP-9-94, 247 m; c) stringer sphalerite and jigsaw fit (arrow shows clast outline), SL91-4, 113.7 m; d) intermediate feldspar-pyroxene–crystal tuff with block- r Rive mudstone, W-13, 86.9 m; d) chiastolite (andalusite) Hargrave H argrave F Ocean-floor rocks Deposit chalcopyrite (arrow) in chloritized footwall , EVP-9-94, mafic feldspar-crystal tuff, 138-17, 46.6 m; e) feldspar- size clasts (arrows show clasts), CP-11-014, 155.5 m; e) McClarty Lake *# crosses in dark grey mudstone, 138-27, 59.1 m; e) McClarty *# *#Kofman Lake 412 m; d) chloritized basalt with quartz amygdules (arrows), crystal tuff with a few flattened mafic lapilli (arrows), 138- silicified basalt with 1 cm quartz amygdules, CP-11-014, Geology of the south Wekusko Lake area (modified from NATMAP quartz diorite intercalated with wacke, 138-27, 147.2 m; EVP-9-94, 379 m; e) coherent dacite and heterolithic tuff 18, 63.4 m; f) weakly laminated mafic tuff, B-73, 70.1 m. 493 m. f) xenoliths of (left arrow) and sulphide (right Harmin Shield Margin Project Working Group, 1998) underlain by hillshade and *# *# Sylvia East *#Fenton breccia, EVP-8-94, 24 m. arrow) in quartz diorite/gabbro, 138-24, 158.5 m. Kisseynew slope analyses of the residual total field magnetic survey. Comorant domain 6 025 000 batholith 6 025 000 Clearwater domain

Cormorant Limestone Rock Types Rock/REEs-Chondrites Rock/Primitive Mantle Lake *# 1000 Moose *# Geochemistry 1 alk. mafic, intermediate, felsic Economic potential Superior rhyolite + phonolite 100 dacite 100 Talbot boundary North Moose Key characteristics trach. 6 000 *# zone 6 000 Lake 10 Talbot .1 tephri- Copper-Man trachy- phonolite Lake Zr/Ti andes. Volcanogenic Cu-Zn-Ag-Au Magmatic Ni-Cu±Co±PGE - Variety of felsic, intermediate and 10 1 Mawdesley deposit andes. + bas.andes. Lake mafic volcanic rocks. - Bimodal (felsic and mafic) volcanic rocks of arc affinity. The Reed Lake–Wekusko Lake area includes Ni- .01 foidite Balloch/Threehouse basalt alk. .1 basalt bas. 400 000 425 000 450 000 475 000 500 000 Ghost/Photo rhyolite - Similar ‘evolved’ geochemical signature as the prolific VMS Cu±Co±PGE sulphide deposits (e.g., Rice Island) and - LREE enriched - similar to rocks of 1 1:750 000 .01 .01 .1 1 10 100 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Nb La Ce Nd Zr Sm Eu Gd Ti Dy Y Er Yb Lu V Sc hosting Chisel sequence of the Snow Lake assemblage. occurrences of Ni-PGE±Co mineralization, indicating 0 10 20 30 40 50 1000 km the mature ‘evolved’ arc of the Snow alk. rhyolite Lake assemblage (see Balloch/ 1 mafic, intermediate, felsic - Widespread hydrothermal alteration (i.e., epidote, chlorite). significant regional potential for these types of deposit, LATE INTRUSIVE SUCCESSOR-ARC PLUTONS OCEAN FLOOR rhyolite + phonolite 100 Threehouse basalt and Ghost/Photo dacite 100 - Known VMS mineralization and potential to contain prolific which have historically received little exploration attention in Late intrusive rocks Intrusive rocks Ocean-floor rocks Domain boundary trach. rhyolite). .1 tephri- 10 SUCCESSOR-BASIN DEPOSITS Ultramafic rocks Synvolcanic mafic to ultramafic Fault CP-11-008 trachy- phonolite VMS deposits like the Snow Lake assemblage. the region south of Wekusko Lake. As such, sulphide- complexes Zr/Ti andes. Missi group Other Phanerozoic boundary edge JUVENILE ARC + SL91-4 andes. + 10 1 - Distinct Nb, Zr, and Ti depletion bas.andes. graphite–rich intermediate tuff and dacite intruded by Missi group volcanic rocks Juvenile-arc rocks Paleoproterozoic and Archean #* Producing mine .01 foidite Compositionally layered gabbro sills characteristic of VMS hosting volcanic alk. .1 Burntwood group Areas of no outcrop Former producer basalt bas. Ghost/Photo rhyolite All data indicate that the area south of Wekusko Lake is gabbro in drillcore 138-24 represent a sub-Phanerozoic and intrusions #* Schist-Wekusko assemblage Synvolcanic tonalite to granodiorite, #* Deposit arc rocks. 1 granite .01 highly prospective for VMS exploration. The volcanic rocks example of a magmatic system that could produce Ni- .01 .1 1 10 100 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Nb La Ce Nd Zr Sm Eu Gd Ti Dy Y Er Yb Lu V Sc Rocks of uncertain age EVOLVED ARC 1000 alk. rhyolite intersected in drillhole 138-15 are reported to contain 1.02% Cu±Co sulphide deposits. Historically, the core was partially Intrusive and supracrustal gneiss Evolved-arc rocks Boundary of drillcore observations - Basalt from WEK-94-3A and 138-26 1 mafic, intermediate, felsic Tectonite, phyllonite, mylonite rhyolite + phonolite 100 are very similar to the Snow Creek and dacite 100 Zn between 58.8 and 60.1 m (Assessment File 92428). A split and sampled for Cu-Zn but not assayed for Ni, Co or Tramping Lake arc-rift/ocean-floor trach. .1 tephri- 10 more recent drillhole (CP-11-006) intersected a platinum-group elements (Assessment File 92428). trachy- phonolite Generalized geology of the exposed and sub-Phanerozoic eastern Flin Flon belt, showing , showing flat chondrite CP-11-014 Zr/Ti andes. normalized REE and imcompatible andes. + 10 1 disseminated sulphide lens between 222 and 234 m that Identifying fertile magmatic systems, similar to Rice Island, major tectonostratigraphic assemblages/domains and volcanogenic massive-sulphide bas.andes. deposits. Box outlines the study area shown in Drillcore observations. Exposed element normalized profiles. .01 foidite Balloch/Threehouse basalt alk. .1 contains sphalerite mineralization, including a short interval will be a part of the focus for future work in the sub- tectonostratigraphic assemblages: FIA, Fourmile Island assemblage; HCA, Hayward basalt bas. Ghost/Photo rhyolite 1 (0.35 m) containing 3.93% Zn (Assessment File 63J1159). Phanerozoic Flin Flon belt. .01 Creek assemblage; M, Missi group; MV, Missi group volcanic rocks; SLA, Snow Lake - Although the Copper-Man and .01 .1 1 10 100 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Nb La Ce Nd Zr Sm Eu Gd Ti Dy Y Er Yb Lu V Sc assemblage; SWA, Schist-Wekusko assemblage. Thick red lines define sub-Phanerozoic Kofman VMS deposits are proximal to 1000 alk. rhyolite domains. each other, the Copper-Man has LREE 1 mafic, intermediate, felsic rhyolite + phonolite and incompatible element enriched dacite 100 100 trach. References: Bailes, A. H. and Galley, A. G. 2001: Geochemistry and tectonic setting of volcanic and intrusive rocks in the VMS-hosting Snow Lake area profiles whereas Kofman has flat REE WEK-94-3A .1 tephri- trachy- phonolite 10 assemblage, Flin Flon Belt, Manitoba: a preliminary release of the geochemical data set; Manitoba Industry, Trade and Mines, Geological Survey, Open File + 138-26 Zr/Ti andes. and incompatible element profiles (see 10 Report 2001-6, 1 CD-ROM.Gagne, S. 2015: Examination of exploration drillcore from the Reed Lake area, Flin Flon belt, west-central Manitoba (parts of andes. + NTS 63K9, 10): implications for the stratigraphy of the Fourmile Island assemblage and setting of VMS deposits; in Report of Activities 2015, Manitoba Simard et al. 2010), possibly bas.andes. 1 Resources, Manitoba Geological Survey, p. 38–51. McDonough, W.F. and Sun, S.S. 1995: The composition of the earth; in Chemical Evolution of .01 foidite Snow Creek/Tramping Lake basalt alk. the Mantle, W.F. McDonough, N.T. Arndt and S. Shirey (ed.), Chemical Geology, v. 120, p.225-234. NATMAP Shield Margin Project Working Group 1998: representing mature and primitive arc basalt bas. Acknowledgements Geology, NATMAP Shield Margin Project Area (Flin Flon Belt), Manitoba/Saskatchewan; Geological Survey of Canada, Map 1968A, scale 1:100 000. settings, respectively. 1 Pearce, J.A. 1996: A users guide to basalt discrimination diagrams, in Trace Element Geochemistry of Volcanic Rocks: Applications for Massive Sulphide .1 The authors thank Royal Nickel Corporation for providing permission to view and sample the core and Gogal Air Services Ltd. for providing assistance in moving core at Th Nb La Ce Nd Zr Sm Eu Gd Ti Dy Y Er Yb Lu V Sc Exploration, D.A. Wyman (ed.), Geological Association of Canada, Short Course Notes, v.12, p.79-113. Simard, R.L., McGregor, C.R., Rayner, N. and .01 .1 1 10 100 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Creaser, R.A. 2010: New geological mapping, geochemical, Sm-Nd isotopic and U-Pb data for the eastern sub-Phanerozoic Flin Flon Belt, west-central Nb/Y the core-storage facility in Snow Lake. The authors thank T. Donak for providing enthusiastic field assistance, as well as N. Brandson and E. Anderson for thorough Manitoba (parts of NTS 63J3-6, 11, 12, 14, 63K1-2, 7–10); in Report of Activities 2010, Manitoba Innovation, Energy and Mines, Manitoba Geological Survey, p. 69–87.Sun, S.S. and McDonough, W.F. 1989: Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes; logistical support. The Geological Society of London, Special Publications, v.42, p.313-345.