Geologic Synthesis, Northern Wopmay Orogen/Coppermine Homocline

Geologic Synthesis, Northern Wopmay Orogen/Coppermine Homocline

L E G E N D 120°00' 112°00' QUATERNARY TURMOIL KLIPPE: Rocks of Turmoil klippe structurally overlie rocks of Coronation Supergroup and Slave craton. They are interpreted to be part of Hottah terrane 119°00' 113°00' 68°00' 68°00' Unconsolidated sediments. 118°00' 114°00' Q Leucogranite: predominantly biotite leucogranite, crosscuts basal contact of Turmoil 117°00' 116°00' 115°00' Wlg klippe. FCg PALEOZOIC FCg Undifferentiated sedimentary rocks: thinly-bedded to laminated shale, mudstone, P 0 PR FCg siltstone, columnar stromatolitic dolomite, minor dolarenite and sandstone; rare Wmyl Mylonitic rocks of uncertain age; dominantly granitic protoliths. 0 PR FCg P 6 FCg Rae River 200 PR gypsum. FCg P PR FCg PR 00 4 NEOPROTEROZOIC HEPBURN INTRUSIVE SUITE (1.900-1.882 Ga; Bowring, 1984) FCg FCg FCg FCg PR PR FCg Coronation sills: gabbro, minor ultramafic cumulate and granophyre WHo Okrark sills: feldspar porphyritic sills of hypabyssal rhyolite, variably foliated and/or PR FCg FCg I O N G U L F (723 Ma; Heaman et al., 1992). lineated. FCg C O R O N A T PR Rich Kugluktuk FCg ardso FCg PR n Ri FCg FCg Syenite: massive pyroxene-amphibole-alkali feldspar syenite, hornblende-biotite N ver FCg Gunbarrel gabbro: medium- to coarse-grained gabbro, forms a gently-inclined O FCg dgg WHs monzonite and quartz monzodiorite (1886 ± 6 Ma; Bowring, 1984). R FCg FCg northeast striking sheet (779.6 ± 1.4 Ma; Harlan et al., 2003). T N H U W N E A PR PR FCg ST V T U FCg FCg Calder gabbro: medium- to coarse-grained gabbro, forms gently-inclined northeast Quartz diorite, diorite, gabbro, norite: massive to weakly-foliated; agmatitic in places 0 T DG FCg 0 E FCg 4 R FCg dc WHd (1882 ± 15 Ma; Bowring, 1984). R CCb striking sheets (779.5 ± 1.8 Ma; Harlan et al., 2003). I TO R FCg PR I ES PR WEo WEr ROCKS OF THE COPPERMINE HOMOCLINE ‘Younger’ granite: massive biotite leuco-monzogranite. FCg WHb FCg FCg NEOPROTEROZOIC AND/OR MESOPROTEROZOIC P PR PR CCb A RAE GROUP Basal sandstone, siltstone, shale and local regolith overlain by reddish to grey cherty Biotite tonalite and granodiorite: typically with alkali feldspar megacrystic border PR dolostone; siltstone, mudstone, silty sandstone; upper cream to orange stromatolitic WHt zones; weakly foliated. FCg dolomite. CHs FCg DG DG WEo CHs MESOPROTEROZOIC WEo FCg ‘Older’ granite: foliated to mylonitic biotite granite, strongly porphyritic in places; may 36 FCg 30' CCb 0 30' COPPERMINE RIVER GROUP WHf CCb DK DS contain abundant metasedimentary enclaves. WEr HUSKY CREEK FORMATION DS CCb WEr CHb DF DS CHs Red sandstone and siltstone. DK DD CHs Garnet granite: mainly biotite granite with accessory garnet, (1887 ± 4 Ma; Bowring, D WHgg 1984); locally contains large tabular alkali feldspar phenocrysts and metasedimentary HL i P CHb FCg HL sm CHs enclaves. al DG WEo FCg DD WGgr L FCg DF WGgr a WEo DD k DG WEo es P WEr Red sandstone and siltstone intercalated with basalt flows. CHs WEr CHb FCg WHg Sheared biotite-hornblende granite: commonly with amphibolite inclusions. WEr FCg WGgr WR WGMs WGMs CHb DK HK HL DL WEo COPPER CREEK FORMATION: Basalt flows and associated breccia, minor sandstone. AKAITCHO GROUP AND BENT GNEISS HE DS FCg CCb HL Undivided rocks of Turmoil klippe: includes gneissic rocks of both igneous and HE WR DD DL 4 WEr 0 WR sedimentary origin (Bent gneiss) and an unconformably overlying sequence (Akaitcho 0 Wm 0 Wa 40 DD MUSKOX INTRUSION (1270 Ma; LeCheminant and Heaman, 1989) Group) of sandstone-siltstone, commonly pyritic, overlain by basaltic and rhyolitic HK 4 CCb Q 8 Kikerk lavas (1.903–1.889 Ga; Bowring, 1984), minor carbonate; includes gabbroic sills; HL DS 0 DG WEr WEo Wm Lake complexly deformed and metamorphosed. Wag: granite. HL WMd WEo WR Cm Gabbro, peridotite, granophyre, websterite. HE CCb Cg DD HOTTAH TERRANE WGg WGMs 0 DF WR 44 Rocks of Hottah terrane occur in the western half of Wopmay orogen HE DG WEr WGg Wm and are interpreted on the basis of lithology, age, and geological relations Coppermine River 240 to be exotic with respect to rocks of Slave craton and Coronation Supergroup DG DS DK FCg Cg Mafic sills of gabbro, diabase, minor granophyre. DK DS WEr WEo DG WEo BELL ISLAND BAY GROUP HK WMd HL DS WR FCg DISMAL LAKES GROUP Basal sandstone and conglomerate overlain by basaltic, andesitic, dacitic, and WGMs Wag GREENHORN LAKES FORMATION: Thin- to medium-bedded dolostone with DS DD WM WB rhyolitic tuff, lava and breccia (1898 ± 7 Ma; Reichenbach, 1991); intercalated CCb DK v stromatolites, cryptalgal laminites, intraclastic breccia, oolite, dolomitic shale, sandstone and mudstone. WGg WEo megabreccia and karstic breccia; local cyclic, medium-bedded dolostone with flat WGg DL DS WEo cryptalgal laminites alternating with thickly-bedded stromatolitic biostromes. Q WMs WEr UNDIFFERENTIATED PLUTONIC ROCKS OF HOTTAH TERRANE WGMs DL DS DF SULKY FORMATION: Planar-bedded to stromatolitic dololutite with interbedded Greenhorn Cm DL Biotite-hornblende granodiorite and monzogranite; minor diorite, quartz diorite, WMs black shale, massive stromatolitic dolomite, cherty carbonate with pisolites, silicified WHp DD Sulky Lake Lakes DK gabbro; 1914 ± 5 Ma and 1902 ± 7 Ma (Bowring, 1984). Q DK DD DD evaporites and tepee structures. 6 WGg 67°00' HE 00 67°00' WGMld DL WEr WEr HOLLY LAKE METAMORPHIC SUITE Wa WEo WEr Q KENDALL RIVER FORMATION: Cherty dolostone, minor chert, silicified evaporites, DK DD WR DK minor black shale, stromatolitic bioherms at top. Cordierite-muscovite schist; sillimanite-mica schist; meta-andesite, basaltic lava and WHm breccia, amphibolite; minor intrusive rocks (2.3-1.94 Ga; Bowring, 1984). HE DD 240 HE HB HK A WMs WEr DL WGg WGg DEASE LAKE FORMATION: Cherty dolostone with lenses of mudstone containing halite HK Cm CORONATION MARGIN DS HK DD casts and rare pisolites; dolomitic sandstone, oolitic dolostone, stromatolitic biostromes, HE HE WGgr WEr WEo intraclastic breccia, mudstone, dololutite; highly contorted megabreccia near Greenhorn WEr HL 0 DL 2 and Sulky lakes. MOREL AND PENINSULAR SILLS DF 7 Kiglikavik WGm HL dW 60 WEo dW HE 0 WGg Lake Mafic to intermediate sills; deformed and metamorphosed; mainly forms a linear HE HL HL WEo A Wm swarm intruding the Rocknest Formation shelf edge; includes large sills to the east Dease Arm WGMs WGp FORT CONFIDENCE FORMATION: Sandy shale, minor sandstone. (Peninsular sills at Napatuklik Lake, 1871±1 Ma, Hamilton, unpublished data cited in WGg WR DF Buchan et al., 2010). HE HE HL WGMld WHgg WEo WR dW Q WGp HL Q WMv CORONATION SUPERGROUP WGMld HB WR WEr Wm TAKIYUAK FORMATION: Brick-red lithic sandstone; minor siltstone and HL WHo WMs DL LEROUX FORMATION: White to grey quartz arenite, conglomeratic litharenite at base. conglomerate; large-scale planar cross-bedding (easterly-directed paleocurrents); HN Q WHt WT A Wa Cm WEo carbonate-clast megabreccia (solution-collapse breccia?) at the base. 0 WHf 0 WHo 4 A WEo HL HN HL WEr WESTERN CHANNEL DIABASE (1.591 Ga; Hamilton and Buchan, 2007) COWLES FORMATION AND KIKERK FORMATION HL WGp WGgr Q WR WGg WEo WEr COWLES FORMATION: Greenish-grey argillaceous limestone rhythmite; minor HB Diabase, gabbro. abiotic stromatolite (seafloor carbonate cement); minor distal feldsphathic-lithic wacke HN A dW WCk WGp Wa turbidites. HN WHt HB WGgr WGgr WEr KIKERK FORMATION: Grey argillite with nodular calcareous concretions; minor HB WHt WR distal feldspathic-lithic wacke turbidites. WGMs WHo WEo PALEOPROTEROZOIC dW WGMs WHf WR WEo WGMld HORNBY BAY GROUP RECLUSE GROUP 0 0 0 6 2 3 WHt WEo ASIAK, FONTANO AND TREE RIVER FORMATIONS WHt Cm NARAKAY VOLCANIC COMPLEX: Mafic lapilli tuff, breccia and ashstone; lithic-rich WGgr HN siliceous ash-flow tuff, rhyolitic flows and associated porphyritic intrusions ASIAK FORMATION: Proximal feldspathic-lithic wackes turbidites; minor grey argillite; WGp WEr WEr (1.663 Ga; Bowring and Ross, 1985). flute clasts indicate south-directed turbidity-current flow; thickens westward; HL Wa WHo WEo WR WGMs WGMs WGp HB Wa intertongues with Fontano, Kikerk and Cowles formations, its base climbing stratigraphically upward from west to east. dW HL WHo 0 WGg 0 30' FONTANO FORMATION: Steel-grey pyritic argillite with regularly-spaced 30' HB 4 KAERTOK FORMATION: Sandstone, mudstone, minor carbonate. WGgr WGd WEr WR HK carbonaceous laminations; tuff bed dated at 1882 ± 4 Ma (Bowring and Grotzinger, dW Hornby Bay C 1992). WGp o p 4 TREE RIVER FORMATION: Pale greenish-grey glauconitic sandstone and siltstone; p 0 WHg WGMs 0 Wa WHgg e WGp r minor granular ironstone: thickens eastward; conformably overlies Rocknest HB m Q dW WGg Wa i WEr WEr EAST RIVER FORMATION: Oolitic calcarenite, laminated and stromatolitic dolostone, Formation to the west, disconformably to the east. n A Wa e HE intraformational conglomerate, minor quartz arenite, evaporite and mudstone. HL WHf R WHb i Wa v EPWORTH GROUP dW WGp WGg e Wm WEo WHd r WEo dW WGMld WHgg ROCKNEST FORMATION: West-facing carbonate-dominated rimmed-shelf and WHo WHf WR Wa WHd Wa WEr slope assemblage; inner-shelf succession of 140–160 upward-shoaling cycles Wa WEr LADY NYE FORMATION: Buff, white and purple sandstone, conglomerate, minor comprised of lagoonal dolomitic argillite and peritidal stromatolitic dolostone with WHb WHb Wm HL mudstone. WGMld WGd Wa WMs WR abundant seafloor cement; shelf rim of non-cyclic supratidal dolostone of tepee and WGgr WGg WEr tepee-breccia facies; outer shore facies of dolostone grainstone and elongate, Wa laterally-linked, columnar stromatolites and stromatolite bioherms, locally with WGgr WHb WR WGgr BIGBEAR FORMATION AND RIVER FORMATION: Red to buff conglomerate, Neptunian dykes; starved scarp and slope facies of dolostone rhythmite, rhythmite WHb WR HB breccia and proximal megabreccia.

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