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 i v n e a MGS y 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 Tuff 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 Felsic 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 Quartz-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: Volcanic rock 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 feldspar-crystal tuff, SL91-3, 60.4 m; b) mafic a) quartz-phyric dacite 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 pyroxene–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 tonalite to granodiorite, granite ( 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 basalt, 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 andesite (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. rhyolite 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.