1
Poulton, T.P., 2017. Report on an examination of photographs of Early Jurassic ammonites collected from the Takwahoni Formation in Cry Lake map area east of Dease Lake and near McBride River, NW British Columbia (NTS 104I) and submitted October 6, 2017, by Bram van Straaten, British Columbia Geological Survey. Geological Survey of Canada, Palentological Report, Fossil Report 11-2017-TPP, 6p. Read, P.B., 1983. Geology, Classy Creek (104J/2E) and Stikine Canyon (104J/1W), British Columbia. Geological Survey of Canada Open File 940, 1:50,000 scale. Read, P.B., 1984. Geology, Klastine River East (104G/16E), Ealue Lake West (104H/13W), Cake Hill West (104I/4W) and Stikine Canyon East (104J/1E), British Columbia. Geological Survey of Canada Open File 1080, 1:50,000 scale. Read, P.B., and Psutka, J.F., 1990. Geology of Ealue Lake East-half (104H/13E) and Cullivan Creek (104H/14) map areas, British Columbia. Geological Survey of Canada Open File 2241, 1:50,000 scale. Stevens, R.D., DeLabio, R.N., and Lachance, G.R., 1982a. Age determinations and geological studies, K-Ar isotopic ages, Report 15, Geological Survey of Canada Paper 81–2, 56p. Stevens, R.D., DeLabio, R.N., and Lachance, G.R., 1982b. Age determinations and geological studies. K-Ar isotopic ages, Report 16, Geological Survey of Canada Paper 82–2, 56p. van Straaten, B.I., Logan, J.M., and Diakow, L.J., 2012. Mesozoic magmatism and metallogeny of the Hotailuh Batholith, northwestern British Columbia. British Columbia Ministry of Energy, Mines and Natural Gas, British Columbia Geological Survey Open File 2012-06, 58p, 1:50,000 scale. van Straaten, B.I., Gibson, R. and Nelson, J., 2017, Preliminary bedrock geology of the Tanzilla and McBride area. British Columbia Ministry of Energy and Mines, British Columbia Geological Survey Open File 2017-9, 1:50,000 scale. van Straaten, B.I., and Bichlmaier, S., 2018. Late Early to Middle Jurassic Hazelton Group volcanism and its tectonic setting, McBride River area, northwest British Columbia. In: Geological Fieldwork 2017, British Columbia Ministry of Energy, Mines and Petroleum Resources, British Columbia Geological Survey Paper 2018-1, pp. 39-66. Wanless, R.K., Stevens, R.D., Lachance, G.R., and Delabio, R.N., 1972. Age determinations and geological studies. K-Ar isotopic ages, Report 10, Geological Survey of Canada Paper 71–2, pp. 96p. References Data sources: Aeromagnetic data: Aeroquest Airborne, 2012. Report on a helicopter-borne magnetic survey (Aeroquest Job #11-046) for Geoscience BC. Geoscience BC Report 2012-2, 11p. Minfile: MINFILE BC mineral inventory, BC Ministry of Energy and Mines, https://minfile.gov.bc.ca/. Accessed June 2016. Topographic data: BC Terrain Resource Information Mapping Digital Map Products, BC Ministry of Forests, Lands and Natural Resource Operations, Crown Registry and Geographic Base Branch, http://geobc.gov.bc.ca/base-mapping/atlas/trim/. Accessed June 2017. Mapping by Bram van Straaten (2011, 2015, 2017), Sebastian Bichlmaier (2017) and JoAnne Nelson (2015) Geology compiled by Bram van Straaten and Sebastian Bichlmaier Cartography by Sebastian Bichlmaier and Bram van Straaten Acknowledgements: We thank Marc Beaton and Rachel Gavin for their capable and enthusiastic assistance during the field season, and Tundra Helicopters for safe flying. We also thank Terry Poulton (Geological Survey of Canada, Calgary) for providing macrofossil age determinations and Richard Friedman (University of British Columbia, Vancouver) for providing preliminary U-Pb zircon geochronology results. Anderson, R.G., Loveridge, W.D., and Sullivan, R.W., 1982. U-Pb isotopic ages of zircon from the Jurassic plutonic suite, Hotailuh Batholith, north - central British Columbia. In:Current Research, Part C, Geological Survey of Canada paper 82-1C, pp. 133-137. Anderson, R.G., 1983. Geology of the Hotailuh batholith and surrounding volcanic and sedimentary rocks, north-central British Columbia. Unpublished Ph.D. thesis, Carleton University, Ottawa, Ontario, Canada, 669p. Anderson, R.G., and Bevier, M.L., 1992. New late Triassic and early Jurassic U-Pb zircon ages from the Hotailuh Batholith, Cry Lake map area, north - central British Columbia. In: Radiogenic age and isotopic studies: Report 6, Geological Survey of Canada Paper 92-02, pp. 145–152. Erdman, L.R., 1978. Petrology, geochronology and geochemistry of Jurassic volcanic and granitic rocks of the Cry Lake and Spatsizi map sheets, north-central British Columbia. Unpublished B.Sc. thesis, The University of British Columbia, Vancouver, B.C., Canada, 63p. Evenchick, C.A., and Thorkelson, D.J., 2005. Geology of the Spatsizi River map area, north-central British Columbia. Geological Survey of Canada Bulletin 577, 276p, 1:250,000 scale. Gabrielse, H., 1998. Geology of Cry Lake and Dease Lake map areas, North-Central British Columbia. Geological Survey of Canada Bulletin 504, 147p, 1:250,000 scale. Golding, M.L., Orchard, M.J., and Zagorevski, A., 2017. Conodonts from the Stikine Terrane in northern British Columbia and southern Yukon. Geological Survey of Canada, Open File 8278, 24 p. Logan, J.M., Moynihan, D.P., Diakow, L.J., and van Straaten, B.I., 2012. Dease Lake - Little Tuya River geology (NTS 104J/08, 07E). British Columbia Ministry of Energy, Mines and Natural Gas, British Columbia Geological Survey Open File 2012-04, 1:50,000 scale. Nelson, J.L., Colpron, M., and Israel, S., 2013. The Cordillera of British Columbia, Yukon and Alaska: Tectonics and metallogeny. In: Colpron, M., Bissig, T., Rusk, B. G., and Thompson, J. (Eds.), Tectonics, metallogeny and discovery: The North American Cordillera and similar accretionary settings, Society of Economic Geologists Special Publication 17, pp. 53–110. 1200 1600 1400 1200 1 4 0 0 1 80 0 1600 1800 1600 1400 1800 1800 1600 1400 1200 1400 1800 1400 1600 1200 1200 1200 1600 1400 18 00 1 6 0 0 1 8 0 0 1 600 14 00 1400 1 4 0 0 1 6 0 0 1 6 0 0 1 800 1000 1200 1200 1400 1600 1600 1400 1200 1400 1600 1800 1200 14 00 1 6 00 1600 1800 180 0 1400 1600 1400 1600 1 80 0 100 0 1200 1200 1 4 0 0 12 00 1 0 0 0 2000 1200 1400 1800 1000 1200 1600 1400 1000 800 800 2000 1800 1600 1400 1200 1600 1400 1800 2000 2 000 1800 1600 800 1200 1000 1400 1000 1 2 0 0 1400 1600 1800 2000 1 6 0 0 1 400 1 000 1 2 0 0 800 800 8 00 1 4 00 2000 1600 1800 1600 1800 1 6 0 0 1200 1 0 00 1 8 0 0 1 6 0 0 1 4 0 0 1400 1200 1000 : : : : : : : : : : : : : : : : 128°45' 58°10' 58°05' 128°50' 58°00' 128°55' 58°15' 129°05' 129°10' 129°00' 57°55' 129°20' 129°15' 128°55' 128°50' 129°10' 58°15' 129°05' 58°10' 58°10' 129°15' 57°55' 58°00' 58°05' 510,000 mE 500,000 mE 490,000 mE 6,460,000 mN 480,000 mE 6,450,000 mN 6,420,000 mN 6,430,000 mN 6,440,000 mN Mt. Sister Mary 40 17 38 11 67 64 7 33 31 64 88 10 12 65 11 7 26 28 35 53 13 45 68 64 75 15 19 26 34 55 21 47 25 49 42 8 20 26 15 6 28 14 26 26 52 39 45 26 72 7 40 31 33 24 11 74 42 61 44 24 40 62 17 29 46 7 8 30 28 15 24 42 22 24 75 24 63 65 54 60 37 50 46 70 Wade Lake S t i k i n e R i v e r M c B r i d e R i v e r Turnagain Lake I009 I010 I016 I027 H010 H028 I015 H029 H030 I093 I100 I101 H009 I021 H007 H027 lJTLv lJTLs PzJCC lJIs uTrSls mJBLs lJTgw lJTLsv uTrSls mJBLs mJBLv lmJHMMv mJBLv mJBLs lJTLv lJTLv uTrSls lJTLsv mJBLs mJBLv lJTLcg lJTLsv mJBLs mJHMUvf EMJf mJBLs lmJHMMv mJHMUvf EMJf lmJHMMv mJBLs lJTLcg lJTLsv lJTLcg JMRdr.fg lJTLs EMJf EMJf mJBLs JMRdr.fg mJBLs EMJf EMJm mJHMUvf DPSsv KSs EMJm EMJf JMRdr.fg lmJHMMv EMJm.po JMRdr JMRgd MPTvm TrSTvm MJTSqm MJTSgr LTrCHqm.le TrSTvm LTrCHqm MJTSgr MJTSqd.fg MJTSgr MJTSqm PzJCC lJTgw lJTLv mJBLs JMRgd mJHMUvm lJTs lmJHMMv EMJm.po EMJm.po lmJHMLvs MJTSgr MJTSqd lmJHMLvm MJTSgr LTrCHqm lmJHMLvm lmJSPs EMJm MJTSqd MJTSgr EMJm.po LTrCHgr MJTSgr LTrCHqm MJTSqm MJTSqm Kehlechoa fault King Salmon fault Pitman fault K e h le ch oa fa ul t D D D U U U U K U Ar Ar U U U K C C C C C F F F F F F F F F F F F F F F F F F F F F C F F F F F Toar-eApt lPli-eToar lSin lSin(?) lPli lPli ePli ePli lPli lPli ePli lSin-ePli lPli lSin lPli(?) In prep. In prep. In prep. In prep. lSin lPli-Toar lSin eToar(?) Sin In prep. In prep. Sin lNor-eRhae eBaj eBaj In prep. mToar In prep. 216.0±1.2 169.0±1.1 169.0±1.3 159±8 173.2±1.4 169.1±0.8 184±8 186±13 In prep. In prep. In prep. In prep. Indet. F lndet. F Toar?-Baj Toar eBaj F eBaj F Rb 191±9 K 150±4 K 185±28 K 142±53 128°45' Fossil data * Location accuracy: High - GPS measurements (this study); Moderate - digitization of fossil locations from 1:100,000 scale map (Gabrielse, 1998, Figure 14); Low - converted from latitude-longitude (Gabrielse, 1998, appendix 2) UTM NAD83 Zone 9N Sample GSC number Easting Northing Location accuracy* Unit Age Fossil descriptions Identified by Source n/a 95019 498997 6441623 moderate mJBLs early Bajocian Poorly preserved inner whorls of ammonite (Sonniniids? indeterminate forms) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95018 499468 6441405 moderate mJBLs early Bajocian Fragment of ammonite (indet., possibly inner whorl of a sonniniid) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95024, 95023, 95020 498788 6441830 moderate mJBLs early Bajocian Impressions and poorly preserved fragments of ammonite (sonniniids, sp. indet.), bivalves (Myophorella sp., Trigoniids, other indeterminate forms), indeterminate corals H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95016 502494 6439876 moderate mJBLs early Bajocian Ammonites (Fragments and distorted specimens of Chondroceras spp. indet., fragments and poor impressions of Stephanoceras s.l.), various brachiopods, pelecypods, gastropods H. Frebold Gabrielse (1998) n/a 95241 493048 6444024 low mJBLs or lJTL Toarcian to early Aptian Belemnites (indet.) J. A. Jeletzky Gabrielse (1998) n/a 95240 493583 6444607 moderate mJBLs or lJTL late Pliensbachian to early Toarcian Belemnites (Nannobelus?), indeterminate pelecypods, indeterminate brachiopods J. A. Jeletzky Gabrielse (1998) n/a 95025, 95026 481195 6439799 moderate lmJSPs Toarcian Ammonite (probably Hildaites sp. ind., other gen. et sp. indet.) H. Frebold, H.W. Tipper, G. Jakobs Gabrielse (1998) n/a 95093 481159 6441653 moderate lmJSPs middle Toarcian Ammonites (Peronoceras verticosum?, Zugodactylites? sp. ind., Harpoceras?, sp. ind., Phymatoceras? sp. ind.) H. Frebold and G. Jakobs Gabrielse (1998) n/a 95251 482474 6441083 moderate lmJSPs Toarcian? - Bajocian Belemnite (Belemnopsis sp. indet.) n/a Gabrielse (1998) n/a 95098 499935 6449077 moderate lJTgw late Pliensbachian Ammonite (Arieticeras cf. A domarense (Meneghini)) H. Frebold Gabrielse (1998) n/a 95021 501627 6448949 moderate lJTgw late Pliensbachian Fragments of ammonites (Amaltheus sp. Margaritatus Group, Protogrammoceras spp. indet.), bivalves (Weyla, trigoniids, others), corals H. Frebold and H.W. Tipper Gabrielse (1998) n/a 94994, 90991, 94986 501834 6447339 moderate lJTgw late Pliensbachian Ammonites (Protogrammoceras spp., Arieticeras cf. algovianum (Oppel), Amaltheus spp., Aveyroniceras spp., Leptaleoceras aff. accuratum (Fucini)), bivalves (trigonids, Weyla?) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95258, 95257, 95268 494106 6448453 moderate lJTgw late Pliensbachian Ammonites (Protogrammoceras?, or Fuciniceras? sp. indet., poor impressions of whorl fragments, Prodactylioceras aff. P. italicum (Meneghini), Prodactylioceras aff. P. meneghinii (Fucini) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 94995 494096 6448922 moderate lJTgw late Pliensbachian Ammonites (Arieticeras spp. indet. impressions of small specimens, Protogrammoceras spp., dactylioceratid impression of inner whorl, Amaltheus sp.) H. Frebold and H.W. Tipper Gabrielse (1998) 17SBI-25-149 V-003872 500357 6448252 high lJTgw early Pliensbachian Ammonites (Tropidoceras) T.P. Poulton Poulton (2017) n/a 90992, 95269 498494 6449118 moderate lJTgw early Pliensbachian Ammonites (Coeloceras? sp., Phylloceras spp., derolytoceratid?, Gemmellaroceras sp., polymorphitid spp., inner whorls of Tropidoceras cf. erythraeum?, Miltoceras? Sp.) H. Frebold and H.W. Tipper Gabrielse (1998) 17SBI-25-148 V-003871 500244 6447909 high lJTgw late Sinemurian to early Pliensbachian Ammonites (eoderoceratacean genera Eoderoceras, Eteoderoceras, Metaderoceras, and perhaps Crucilobiceras) T.P. Poulton Poulton (2017) n/a C-95096, 95091, 95101 499982 6445190 low lJTL early Toarcian(?) Faint impressions and poorly preserved fragments of ammonites (harpoceratid, Arnioceras?, other gen. et sp. indet.) H. Frebold and G. Jakobs Gabrielse (1998) n/a 95261 - 95266 497969 6447378 moderate lJTLs late Pliensbachian to Toarcian Ammonites (Dactylioceratidae, gen. et sp. indet, impressions of small fragments of Protogrammoceras? sp. indet., Harpoceras sp. ind., Hildaites sp. ind., other gen. et sp. indet.) H. Frebold, H.W. Tipper, G. Jakobs Gabrielse (1998) n/a 95269 499759 6447274 moderate lJTLs late Pliensbachian(?) Very poorly preserved small ammonites (Protogrammoceras sp. indet., impression of a distorted fragment of Arieticeras? sp. indet. showing keel with shallow sulci) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 94991 493457 6448295 moderate lJTL? early Pliensbachian Poorly preserved ammonite (Dubariceras sp. indet.) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95015 500005 6447324 moderate lJTLs late Sinemurian Ammonites (Paltechioceras cf. rothpletzi (Bose), coarsely ribbed Paltechioceras sp., Plesechioceras? sp. Phylloceras sp.), many genera and species of bivalves H.W. Tipper Gabrielse (1998) n/a 95094 501877 6446596 moderate lJTLs late Sinemurian Ammonites (Paltechioceras sp., Phylloceras sp.), numerous and varied bivalves H.W. Tipper Gabrielse (1998) n/a 94993, 90996 501319 6445156 moderate lJTLs late Sinemurian Ammonites (Paltechioceras cf. harbledownensis (Crickmay), faint impression of Crucilobiceras sp. indet. showing two rows of spines, Juraphyllites n. sp.?), wide variety of bivalves H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95099 495094 6445413 low lJTLs late Sinemurian Ammonites (Gleviceras sp., and aptychi) H.W. Tipper Gabrielse (1998) n/a 94990 493492 6445755 moderate lJTLs late Sinemurian? Poorly preserved ammonite fragments (Astroceras?) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95256 499937 6444329 moderate lJTLs Sinemurian Fragments of a small ammonite (probably Arnioceras) H. Frebold Gabrielse (1998) n/a 95092, 95095 499920 6443564 moderate lJTLs? Sinemurian Ammonites (Epophioceras aff. E. carinatum Spath, Gleviceras sp., Arnioceras sp., Asteroceras cf. A. varians Fucini) H. Frebold and H.W. Tipper Gabrielse (1998) n/a 95051, 95057 500570 6445754 moderate lJTLs Indet. n/a n/a Gabrielse (1998) n/a 95107 493137 6448199 low lJTL? Indet. Bivalves, indet. E.T. Tozer Gabrielse (1998) 17SBI-22-123 V-003861 501320 6447523 high Limestone block in lJTLsv In prep. In prep. M.L. Golding Golding, pers. comm. 17SBI-23-125 V-003862 499851 6447971 high Limestone clasts in lJTLsv In prep. In prep. M.L. Golding Golding, pers. comm. n/a C-117416 499412 6443716 moderate uTrSls late Norian - early Rhaetian Hexacorals (indet.), fragmentary pelecypods (indet.), ichthyoliths, conodonts (Mockina bidentata (Mosher 1968); Mockina englandi (Orchard 1991)) M. J. Orchard and M.L Golding Gabrielse (1998); Golding et al. (2017) 17BvS-23-208 V-003859 501349 6442602 high uTrSls In prep. In prep. M.L. Golding Golding, pers. comm. 17BvS-23-212 V-003860 500535 6443750 high uTrSls In prep. In prep. M.L. Golding Golding, pers. comm. 17SBI-28-192 V-003863 512188 6446347 high uTrSls In prep. In prep. M.L. Golding Golding, pers. comm. Sample Easting Northing Unit Age (Ma) Type Mineral Sample description Source AN-78-467 493616 6434342 JMRgd 166±8 U-Pb Zrn Hbl-Bt-bearing granodiorite Anderson et al. (1982)* AN-78-467 493616 6434342 JMRgd 184±8 U-Pb Zrn Hbl-Bt-bearing granodiorite (re-analysis of AN-78-467) Anderson and Bevier (1992)* AN-78-467 493616 6434342 JMRgd 186±13 K-Ar Hbl Hbl-Bt-bearing granodiorite Stevens et al. (1982a)* 17BvS-6-36 491425 6432627 JMRgd In prep. U-Pb Zrn Hbl-Bt granodiorite This study 11BVA31-232 478755 6434626 MJTSgr 169.1±0.8 U-Pb Zrn Hbl-bearing Bt monzogranite van Straaten et al. (2012) GAD 67-132-3 477914 6443782 MJTSqm 159±8 K-Ar Hbl Leucocratic Hbl-Bt-bearing Qtz monzonite or granodiorite Wanless et al.(1972), Anderson (1983)* 11BVA35-276 480640 6439273 MJTSqm 169.0±1.1 Ar-Ar Bt Hbl-bearing Bt Qtz monzonite to monzogranite van Straaten et al. (2012) 11BVA35-276 480640 6439273 MJTSqm 169.0±1.3 U-Pb Zrn Hbl-bearing Bt Qtz monzonite to monzogranite van Straaten et al. (2012) AN-79-719-1 480471 6435640 MJTSqd.fg 150±4 K-Ar WR Fine-grained quartz diorite Stevens et al. (1982b)* 11BVA42-332 479794 6436014 MJTSqd.fg 173.2±1.4 Ar-Ar Hbl Fine-grained Hbl-Bt Qtz diorite van Straaten et al. (2012) 17SBI-10-60 495568 6426021 mJBLcg In prep. U-Pb Zrn (D) Medium grained sandstone This study 17SBI-16-88 496183 6435581 mJHMUvf In prep. U-Pb Zrn Felsic tuff This study 17SBI-37-301 498815 6431164 mJHMUvf In prep. U-Pb Zrn Flow-banded Pl porphyry This study 117c, 118b, 119b, SphRhy 493980 6429991 lmJHMMv, EMJf(?) 191±9 Rb-Sr WR Flow-banded maroon Pl-phyric volcanic rock, grey Aug-Pl crystal tuff, grey Aug-Pl-phyric volcanic rock, spherulitic rhyolite Erdman (1978) 17BvS-19-159 481756 6441786 lmJHMLvf In prep. U-Pb Zrn Felsic lapillistone to lapilli tuff This study 17BvS-25-238 498661 6447266 lJTLcg In prep. U-Pb Zrn (D) Polymictic conglomerate with limestone and volcanic clasts This study 17BvS-25-242 500472 6447222 lJTLsv In prep. U-Pb Zrn (D) Feldspathic arenite to volcaniclastic sandstone This study AN-79-718-1 481553 6434837 LTrCHqm.le 142±53 K-Ar Hbl Leucocratic Hbl granodiorite Stevens et al. (1982b)* AN-79-718-1 481553 6434837 LTrCHqm.le 185±28 K-Ar Hbl Leucocratic Hbl granodiorite Stevens et al. (1982b)* 11BVA38-304 481362 6439991 LTCHgr 216.2±1.2 U-Pb Zrn Hbl-bearing granodiorite to monzogranite van Straaten et al. (2012) Geochronology data * Location digitized from 1:100,000 scale map (Gabrielse, 1998, Figure 14) B B’ B’’ A A’ A’’ C’’’ C’’ C’ C Kehlechoa fault Elevation (km) 2 1 0 A A’ A’’ Cake Hill pluton Fm. Spatsizi Takwahoni Fm. Stikinia Whitehorse trough Horn Mountain Formation Stikinia B B’ B’’ McBride River pluton Mtn Fm. Bowser Lk. Gp. Bowser Lk. Gp. Horn Horn Mountain Formation Elevation (km) 2 1 0 Schematic vertical cross-sections ? C’- C’’ 1 2 0 Kehlechoa fault King Salmon fault C’ C C’’ C’’’ Elevation (km) Pitman fault Formation pluton Bowser Lk. Gp. Sustut Group Whitehorse trough Stikinia Cache Creek Horn Mountain Horn Mountain Formation Bowser Lake Group Bowser Lake Group Takwahoni Formation lower unit Takwahoni Formation greywacke unit Sinwa Fm. McBride River B’- B’’ ? Altered or gossanous rocks Outcrop (darker shade) Contact: defined, approximate, inferred from aeromagnetic data, inferred Unconformity: defined, approximate, inferred Fault: defined, approximate, inferred from aeromagnetic data, inferred Thrust fault: defined, approximate, inferred from aeromagnetic data, inferred (tooth on hanging wall) Normal fault: defined, approximate, inferred from aeromagnetic data, inferred (dot on hanging wall) Bedding: tops unknown; tops known, right-way-up; tops known, overturned Foliation Geochronology sample site: U-Pb zircon, U-Pb detrital zircon, Ar-Ar, K-Ar, Rb-Sr Field station: 2011; 2015; 2017 Sample site: fossil, conodont Minfile (104) Symbols F U D Ar K C Rb Hornblende quartz monzodiorite Leucocratic hornblende quartz monzodiorite Early to Middle Jurassic, Horn Mountain intrusions Hornblende granodiorite to monzogranite Felsic intrusive Fine-grained hornblende-biotite quartz diorite Platy plagioclase porphyry Mafic intrusive Late Triassic, Cake Hill pluton Hornblende-biotite granodiorite Hornblende-clinopyroxene(?) diorite to quartz diorite Middle Jurassic, Three Sisters pluton Jurassic, McBride River pluton Biotite monzogranite Mafic-rich microdiorite Hornblende-rich quartz diorite Biotite quartz monzonite Feldspathic wacke, siltstone and phyllite Upper Triassic, Sinwa Formation Lower Jurassic, Inklin Formation Limestone Undivided Cache Creek Paleozoic to Jurassic Intrusive rocks uTrSls PzJCC MJTSgr MJTSqm MJTSqd EMJm.po EMJm LTrCHgr LTrCHqm lJIs JMRgd JMRdr EMJf JMRdr.fg LTrCHqm.le MJTSqd.fg Argillite and siltstone facies Volcaniclastic sandstone facies Mafic volcanic facies Conglomerate facies Siltstone with lesser feldspathic arenite Phyllitic greenstone and phyllite Whitehorse trough Lower Jurassic, Laberge Group Lower Jurassic, Takwahoni Formation Devonian-Permian, Stikine assemblage Feldspathic wacke, feldspathic arenite and lesser siltstone Lower unit Sandstone, conglomerate and shale Upper mafic volcanic rocks Upper felsic volcanic rocks Mafic volcanic rocks Lower to Middle Jurassic, upper Hazelton Group Middle Jurassic, Horn Mountain Formation Lower to Middle Jurassic, Horn Mountain Formation Triassic, Stuhini Group Middle maroon volcanic rocks Lower mafic volcanic rocks Lower volcaniclastic sandstone Argillite, siltstone and sandstone Mafic volcanic rocks Lower to Middle Jurassic, Spatsizi Formation Miocene-Pleistocene, Tuya Formation Middle Jurassic, Bowser Lake Group Overlap assemblages Stikinia Olivine basalt Undivided sedimentary rocks Stratified rocks Cretaceous, Sustut Group MPTvm KSs mJBLs mJBLv mJHMUvm mJHMUvf lmJHMMv lmJHMLvm lmJHMLvs lmJSPs TrSTvm lJTs lJTgw lJTLv lJTLs lJTLcg DPSsv lJTLsv Legend unconformity Tectonic contact Tectonic contact unconformity Upper Triassic, Sinwa Formation Limestone uTrSls unconformity (for detailed unit descriptions the reader is referred to van Straaten and Bichlmaier, 2018) 104J/02 104G/16 104G/15 104J/01 104J/08 104J/07 104J/09 104J/10 104H/14 104H/13 104I/03 104I/04 104I/06 104I/05 104I/12 104I/15 104I/08 104I/07 104I/02 104I/09 104I/01 104I/16 58.5 ° 58 ° 104I/10 - 128.5 ° 104I/11 Dease Lake 37 This study van Straaten et al. (2017) van Straaten et al. (2012) Evenchick and Thorkelson (2005) Gabrielse (1998) Read and Psutka (1990) Read (1984) Read (1983) Anderson (1983) Previous mapping in the region Logan et al. (2012) Grid north Magnetic north True north Magnetic declination 19° 11.40' E Convergence angle 0° 4.26' W Approximate mean declination 2018 for centre of map Annual change, decreasing 17.2' -129.5 ° -130.5 ° 0 2 4 km 1:50,000 scale Universal Transverse Mercator Projection, North American Datum 1983, Zone 9 North, 20 m contour intervals British Columbia Geological Survey Open File 2018-3 Preliminary bedrock geology of the McBride River area Parts of NTS Sheets 104H/14,15; 104I/02, 03, 06 Bram I. van Straaten and Sebastian J. Bichlmaier G Y E E O V L R O U G S I C A L C O L H U S M I T B I I R A B Atlin Prince Rupert Smithers Kamloops Prince George Vancouver Victoria Dease Lake Stewart Location map Terranes (after Nelson et al., 2013) Ancestral North America Intermontane terranes Coast plutonic complex Insular terranes Outboard terranes Stikinia (ST), Cache Creek (CC), Quesnellia (QN), Yukon-Tanana (YT) and others ST ST CC QN QN CC YT YT Recommended citation van Straaten, B.I. and Bichlmaier, S.J., 2018. Preliminary bedrock geology of the McBride River area. British Columbia Ministry of Energy, Mines and Petroleum Resources, British Columbia Geological Survey Open File 2018-3, 1:50,000 scale.
