Carbonatites, Nepheline Syenites, Kimberlites and Related Rocks;In British Columbia

Home , Igneous textures, Nepheline syenite, Syenite

Province of British Columbia MINERAL RESOURCES DIVISION Ministry of Energy, Mines and Geological Survey Branch Petroleum Resources Hon. Anne Edwards, Minister

CARBONATITES, NEPHELINE SYENITES, KIMBERLITES AND RELATED ROCKS;IN BRITISH COLUMBIA

This is a Contribution to the CanaddBritish Columbia Mineral Development Agreement1985-1990

By Jennifer Pel1

BULLETIN 88 Canadian~~ ~~~~~~~ Catalooulno ~ -~ in Publication Data Pell, Jennifer,1956- Carbonatites, nepheline syenites, kimberlites and relatedrocks in British Columbia (Bulletin, ISSN 0226-7497 ;88) Issued byGeologicalSurveyBranch. 'This is a Contribution to the CanadaIBritisb Columbia Mineral Development Agreement 1985-1990." Indudes bibliographical references: p. ISBN 0-77262170-5 1. Carbonatites -British Columbia. 2. Nepheline Field Research furthis project was caniec! uut syenite -British Columbia. 3. Kimberlite - British durizgtheperiod 1984 to 1990 Columbia. 4. Geology, Economic - British Columbia. 5. Geochemistry - British Columbia, 6.Petrology - British Columbia. I. British Columbia. Ministry of Energy, Mines and Petroleum Resources. 11. British Columbia. GeologicalSurveyBranch. 111. CanadalBritish Columbia Mineral Development Agreement. IV. Title. V. Series: VICTORIA Bulletin (British Columbia. Ministry of Energy, Minesand BRITISH COLUMBIA Petroleum Resources) ; 88. CANADA

TN27.B7P44 1994 553.6'09711TN27.B7P44C94-960219-1 1994 July 1994 Ministry of Energx Minesand Petroleum Resources

TABLE OF CONTENTS”

INTRODUCTION...... 1 Geochemistry...... 36 Distributiongeneral and characteristics of Geochronology ...... 36 carbonatites and nephelinesyenites ...... 2 Distribution and general characteristics of CARBONATITES AND SYENITE GNEISS COMPLliXES IN METAMORPHOSED PRECAMBRIAN EARLY kimberlites and alkaline ultrabasic diatreme TO CAMBRIAN STRATA. OMINECA BELT ...... 31 breccias ...... 3 Manson Creek area (93N/9) ...... 37 Geological work ...... 5 Carbonatites ...... 37 Acknowledgments...... 5 phases 38 Silicate phases ...... Fenites ...... 38 CARBONATITE AND SYENITE COMPLEXES IN Geochemistry ...... 39 PALEOZOIC STRATA, ROCKYAND CASSIAR Geochronology ...... 40 MOUNTAINS. FORELANDBELT ...... 7 Mount Bisson- Mnnroe Creekarea (93N/9; The Aley Carbonatite complex(94B/5) ...... 7 930/5. 12)...... 41 Rauhangite core zone...... 41 7 rocks Alkalic dike ...... Sovite zones...... 7 Pegmatites...... 42 ‘Am phibolitic’ margin ‘Amphibolitic’ ...... 7 Intrusive breccias ...... 42 Alteration halo ...... 8 Fenites ...... 42 Rare-earth-bearing dikes ...... 11 Quartz monzonitesand quartz syenites ...... 42 Geochemistry ...... 11 Geochemistry...... 42 Geochronology...... 11 Geochronology ...... 43 Wicheeda Lake complex(Prince and George Blue Riverarea (83D/3. 6. 7) ...... 43 claims, 93V5; 93J/8, 9) 11 ...... Carbonatites ...... 44 Carbonatites andassociated syenitic rocks ...... 13 Nepheline syenites ...... 44 Alkaline dikes ...... 13 Mafic Silicate Rocks ...... 44 Geochemistry ...... 13 Fenites ...... 47 Geochronology...... 14 Geochemistry ...... 47 BearpawRidge sodalite syenite (93V4)...... 14 Geochronology ...... 53 Sodalite syenite ...... 15 Trident Mountain (82M/16) ...... 53 Nonda formationvolcaniclastic rocks ...... 16 Geochemistry...... 54 Orthogneiss...... 16 Geochronology ...... 54 Postorogenic syenite ...... 17 Geochemistry ...... 17 CARBONATITES AND SYENITE GNEISSCOMPLEXES Geochronology...... 18 ASSOCIATED WITH CORE GNEISSES INTHE Oh! INECA Ice River complex (82N/1)...... 18 BELT ...... 55 Ultramafic series ...... 18 Mount Copeland nephelinesyenite gneisses Zoned syenite complex ...... 19 (82W2) ...... 55 Carbonatites...... 19 Nepheline syenite gneisses ...... 55 Lamprophyres ...... 20 Alkaline amphibolite...... 58 Geochemistry ...... 22 Grey syenruc.. gneiss ...... 58 Geochronology...... 23 Geochemistry ...... 59 Rock Canyon Creekfluorite and rare-earth Geochronology ...... 60 element showing(82J13E) ...... 24 Carbonatites and associated rocks. west flank, Minerahzatlon...... Frenchman Cap 25 dome (82W2, 7, 10) ...... 60 Geochemistry ...... 25 Perry River intrusive carbonatites (82Wr)...... 60 Geochronology...... 27 Fenites - Perry River area ...... 60 Kechika Riverarea (94L/ll, 12, 13) ...... 27 Ratchford Creek (Ren)intrusive carbona:ite Distribution and field relationships of (82W7) ...... 62 alkaline rocks ...... 28 Intrusive syenite - Perry River area Petrography: syenites ...... 30 (82W7, 10) ...... 62 Petrography: trachytes ...... 31 Mount Graceextrusive carbonatite Petrography: (82W7, 10)...... 63 feldspar-quartz-carbonate-sericiterocks .....31 Geochemistry ...... 66 Petrography: carbonatites...... 34 Geochronology ...... 68

_- Bulletin 88 iii Three Valley Gap (82L/16)...... 68 Carbonatites and syenite gneisses ...... 111 Carbonatites, fenites, syenites ...... 69 Kimberlites. lamprophyres andother ultrabasic Geochemistry...... 70 diatremes...... 111 Geochronology ...... 70 Tectonlc lmphcattons ...... 113

ULTRABASIC DIATREMESIN NORTHERN BRITISH REFERENCES ...... 119 COLUMBIA...... 71 The Kechika River diatreme andrelated rocks APPENDICES ...... 125 (94L/12, 13)...... 71 COLOUR PHOTOS ...... 135 Lithology ...... 71 Geochemistry...... 73 FIGURES Geochronology ...... 74 1. Index map, carbonatite and syenite gneiss Ospika Pipe(94B/5) ...... 74 complexes ...... 2 Lithology ...... 74 2Index . map, alkaline ultrabasic diatremeswanns ...... 4 Geochemistry...... 75 3. Geological map, Aleycarbonatite complex...... 6 Geochronology ...... 76 4 . Major elementternary plots of carbonatites and "amphibolite"margin, Aley complex 10 ULTRABASIC DIATREMES IN THE GOLDEN - ...... COLUMBIAICEFIELDSAREA ...... 77 5 . Chondrite-normalizedrare-earth element plots, Bush Riverarea (Larry claims)complex (83C13) ...... 77 Aley ...... 10 Lens Mountainand Mons Creekareas (Jack and Ternary 6 . plots for fenites.Aley complex...... 10 Mike claims) (82N/14. 15)...... 81 7 . Location map of the intrusive bodies on the Prince Valenciennes River pipes and George groups of claims. WicheedaLake ...... 11 (Mark claims) (82N115) ...... 83 8. Geological map of thePrince grid, Wicheeda Lakt: .. 12 The HPPipe(82N/10) ...... 84 9 . Chondrite-normalized rare-earth element plot. Geochemistry of diatremes andrelated dikes ...... 87 WicheedaLake alkaline complex ...... 13 Geochronology...... 87 10. Geologicalmap of Bearpaw Ridge ...... 14 11 Alkali-silica and agpaitic index plots, ULTRABASIC DIATREMES IN THE BULL RIVER - . ELK RIVER AREA. SOUTHERN BRITISH COLUMBIA17 Bearpaw Ridge ...... (82G.3) ...... 91 12. Majorelement ternary plots. BearpawRidge ...... 17 Shatch Mountainarea (Joff claims) (82Jlll) ...... 91 13. Geology ofthe Ice River complex...... 19 The Russell Peak diatremes(82J/6) ...... 92 14. Alkali-silica and agpaitic index plots. Ice River Blackfoot andQninn diatremes (82G114) ...... 94 ultramafic suite ...... 22 Mount Haynes- Swanson Peakarea (Swan 15. Ternary majorelement plots. Ice River ultramafic claims) (82G/14) ...... 95 suite...... 22 The Mary Creek - White Riverbreccia dike 16. Alkali-silica and agpaitic index plots, Ice River (823/3W) ...... 96 syenltlc... sulte ...... 23 The Summer The pipes96 (82G/ll) ...... 17. Ternary major elementplots, Ice River syenitic Geochemistry of diatremes anddikes ...... 99 suite ...... 23 Geochronology...... 101 18. Major element ternary plot. Ice River complex carbonatites ...... 23 KIMBERLITES IN BRITISH COLUMBIA...... 103 The Crosskimherlite (82J/2) ...... 103 I9. Geology of the Rock Canyon Creekfluorite/ Geochemistry ...... 105 rare-earth showing...... 25 Geochronology...... 105 20. Chondrite-normalizedrare-earth plot. Rock Canyon Creek fenites ...... 27 ECONOMIC CONSIDERATIONS AND EXPLORATION Generalized 21. geology,Kechika area ...... 28 POTENTIAL ...... 107 22 . Geology of the central part of the belt of alkaline Niobium and tantalum...... 107 rocks. Kechikaarea ...... 29 Rare-earth elements and yttrium...... 107 23. Alkali-silica and agpaitic index diagrams. Kechika Zirconium ...... 108 syenites ...... 32 Phosphates ...... 108 24. Major elementternary plots. Kechika igneous Nepheline.. and nephelinesyenite ...... 109 suite ...... 32 Vermrcuhte ...... 109 25 . Carbonatite ternary plot, Kechika suite ...... 34 Molybdenum ...... 109 26. Chondrite-normalizedrare-earth plots, Kechika Wollastonite ...... 109 suite ...... 34 Titanium...... 109 Diamond ...... 109 27 . Geological map ofthe Lonnie carbonatite complex.. 37 Gemstones ...... 110 28 . Carbonatite plot. Lonnie complex...... 39 29. Major elementternary plots, Manson Creekarea SUMMARY AND CONCLUSIONS ...... 11 1 carbonatite complexes ...... 40

iV Geological Suwey Branch Ministry of Enemy. Minesand Petmleum Resouxes

30. Ternary fenite plots. Manson Creek area carbonatite 64. General geology and diatreme locations in the complexes ...... 40 Golden .Columbia Icefields area ...... 77 31. Alkali-silica and agpaitic index plots, Lonnie 65. Diatreme breccias and dikes. Bush Riverarea ...... 77 complex silicate rocks ...... 41 66. Sketch showingdistribution of diatreme andrelated 32. Chondrite-normalizedrare-earth plots, Lonnie rocks on theJack claims. Lens Mountainarea ...... 81 and Vergil showings, Manson Creek area ...... 41 67. Diatreme breccias and dikes. Valenciennes River 33. Geology and carbonatitekyenitelocalities in area ...... 82 the Blue Riverarea ...... 42 68. GeologyHP ofthe pipe ...... 84 34. Geological mapof the Howard Creek carbonatite 69. Major elementdiscriminant diagrams, Golden occurrence...... 44 diatreme swarm...... 88 35 . Geological map andcross-section, Paradise Lake 70 . Major element ternary pIots, Golden diatremes...... 88 area ...... 45 71. Ni-Cr plot, Golden diatremes...... 88 36. Major elementternary plots, Blue River area 72. SrRb vs. TiOz, Golden diatremes andrelated alkaline rocks ...... 48 dikes ...... 89 37 Carbonatite 37. plot, RiverBlue area ...... 48 73. General geology and diatremelocations in tht: 38. Ternary fenite plots, BlueRiver area rocks...... 48 Bull River- White Riverarea ...... 90 39. Alkali-silica and agpaitic index plots. Blue 74. Geology ofthe Joff pipe, Shatch Mountainar.a ...... 91 River area syenites ...... 50 75. Geology of the Russell Peak diatreme...... 92 40 Chondrite-normalizedrare-earth plots, Blue River . 76. Geology of the Blackfoot diatreme...... 94 area showings ...... 50 77 Stratigraphy, Swanson Peakarea 95 41 . Geology of theTrident Mountain Area, Selkirk ...... Mountains ...... 51 78. Diatreme breccias, Summer andGalbraith 42. Alkali-silica and agpaitic index plots, Trident creeks area ...... 97 Mountain syenites ...... 52 79 . Major elementternary plots, southern diatremes...... 99 43. Major elementternary plots, Trident Mountain 80. Major element discriminant plots, southern syenites ...... 100 swarm 53 diatreme ...... 44. Geology of the FrenchmanCap area ...... 56 Ni81 . = Cr plot, southerndiatremes 100 ...... 45 . Geological map, Mount Copelandarea ...... 57 82. Sketch of the Crossing Creekkimberlite pipe 46. Alkali-silica and agpaitic index plots, Mount facing north ...... 102 Copeland syenites ...... 59 83. Major elementdiscriminant plots, Cross 47. Major elementternary plots, Mount Copeland kimberlite ...... 103 syenites ...... 59 84. Majorelement ternary plots,Cross kimberlite ...... 103 48 . Carbonatite plot, Mount Grace andPerry River 85. Ni = Cr plot, Cross kimberlite ...... 104 areas ...... 65 86. Structural position ofdiatremes ...... 112 49. Chondrite-normalizedrare-earth plots. carbonatites, 87 . (a) Carbonatites and related rocks in Western west flank, FrenchmanCap dome ...... 65 North America (b)Diamonds and diatremes i:1 50. Detailed section of the Mount Gracecarbonatite, Western North America...... 116 Blais Creek showing...... 66 51. Alkali-silica and agpaitic index plots. Perry River TABLES syenites ...... 66 1. Chemical analyses. Aley carbonatite complex ...... 9 52. Major elementternary plots, Perry River and 2 . Chemical analyses. Bearpaw Ridge...... 16 Mount Gracearea alkaline rocks...... 67 3. Chemical compositionsof Ice River 53. Fenite plots. Perry Riverarea ...... 67 complex rocks...... 21 54. Carbonatite plot. Three Valley Gap ...... 69 4 . Ice River complex- geochronology summary ...... 24 55. Major elementternary plots. Three Valley Gap ...... 69 5. Chemical analyses. Rock CanyonCreek ...... 26 56. Chondrite-normalizedrare-earth plot, Three 6 . Geochemistry of selected samples, Kechika area .....33 Valley Gap ...... 69 7 . Chemical analyses of alkaline rocks, Manson 57. Major elementdiscriminant plots. Kechika diatreme Creek area ...... 39 and related dikes and tuffs ...... 72 8 . Chemical analyses of alkaline rocks, Blue River 58. Major elementternary plots, Kechika diatremeand area ...... 49 related rocks ...... 72 9 . Chemical analyses of Trident Mountain syenites...... 53 59. Ni-Cr plot, Kechika diatreme, dikes and tuffs ...... 72 10. Chemical composition of selected rocks from the 60. Chondrite-normalizedrare-earth plot, Kechika Mount Copelandsyenite complex ...... 58 diatreme andrelated dikes and tuffs ...... 73 11. Chemical analyses of alkaline rocks, west fla.~k. 61. Major elementdiscriminant plots. Ospika pipe ...... 74 Frenchman Cap Dome...... 64 62. Major elementternary plots, Ospika pipe...... 75 12. Chemical analyses, Three Valley Gap,alkalir e 63. Ni-Cr plot, Ospika pipe...... 75 rocks ...... 68

Bulletin 88 V 13. Geochemistry of selected diatreme breccias and 24. Intrusive carbonatite band surrounded by dark related dikes and tuffs, Kechika area ...... 71 amphibolite fenite and some grey syenitic fenite, 14. Chemical analyses, Ospika pipe...... 74 Perry River area ...... 60 15. Field characteristics of HP pipe breccia phases ...... 84 25. Swirled carbonatite in amphibole fenite, Peny 16. Chemical analyses, Golden area diatremes...... 86 River area ...... 61 17. Chemical analyses, Bull River- Elk River 26. Interlayered amphibolitic fenite and syenitic fenite, diatremes anddiatremes related rocks ...... 98 Peny River area ...... 61 18. Chemical analyses, CrossingCreek kimberlite...... 104 27. Ratchford Creekcarbonatite interlayered with 19. Timingof alkaline intrusion and orogenesis...... 114 amphibolitic fenite and containing fenitized fragments of country rock ...... 62 PLATES 28. Part of the thickened section of the Mount Grace 1. Xenoliths of quartzite and syenite in the breccia extrusive carbonatite ...... 63 phase of the "amphibolitic" margin, Aley complex..... 8 29. Interbedded sedimentary marble withcarbonatite 2. Quartzite xenoliths weathering ontof the agglomerate and tuff layers; Mount Grace "amphibolite"margin, Aley complex8 ...... carbonatite near Blais Creek ...... 63 30. Large feldspar clots in biotite-rich carbonatite, 3. REE-enriched dikes in carbonate hostrocks, Aley complex...... 8 Three Valley Gap area ...... 68 31. Dolostone clast with reaction rim, Ospikapipe 73 4. Boulder containingsyenite dike crosscutting ...... bonded volcaniclastic rocks,Bearpaw Ridge15 ...... 32. Rusty weathering,clast-supported megabreccia, Bush River area 78 5. White-weathering syenite with disseminated ...... sodalite,Ridge Bearpaw ...... 15 33. Dark greenweathering breccia, Bush Riverarea ... ..78 6. Folded andfoliated dioritic orthogneiss exposed, 34. Limestone-cored annoured xenolith in diatreme B earpaw Ridge Bearpaw ...... 15 breccia,River Bush area ...... 79 35. Alteredmica macrocrystin diatreme breccia, 7. Contact betweensyenites of the Ice River complex Bush River Bush area ...... 79 and steeply dipping carbonaterocks, Bntress Peak .... 18 36. Boulder from dike,a Bush Riverarea with breccia 8. Jacupirangite cut by fine-grained nepheline syenite core and finer grained, macrocryst-rich rim 79 dikelets, north of Mount Mollison,Ice River ...... complex...... 20 37. Laminated margin of a fine-grained dike, Bush River area ...... 79 9. White-weathering, coarse-grainedcarbonatite dike, Mount Sharparea, Ice River complex ...... 20 38. Photomicrograph ofan altered pyroxene crystal in a matrix containing abundant altered mica 10. Intrafonnational conglomerate with fluorite matrix, from a dike, Bush River area ...... 80 Rock Canyon Creek 27 ...... 39. Fragments of sedimentary rocksin a buff- 11. Potassium feldspar porphyroclasts in a fine-grained weathering, quartz xenocryst-rich breccia, carbonate-sericite-feldspar-quartzCreekmatrix from a Mons ...... 80 sheared leucosyenite, Kechika area 30 ...... 40. Photomicrograph ofquartz xenocryst-rich breccia, 12. Typicaltrachyte, Kechika area ...... ,30 similar to that shown in previous plate ...... 80 13. An apatite-rich zone in the quartz-feldspar-sericite- 41. Serpentinized olivine macrocrysts in a fine- carbonate-(apatite) rocks, Kechika area ...... 31 grained, massive diatremephase, Valenciennes 14. Blue pleochroic amphibole andfiner grained River area ...... 82 aegirine in ultrafenite, Lonnie area ...... 38 42. Boudinaged dikesubparallel to bedding in 15. Fz folds in banded nephelinesyenite, Paradise buff-coloured carbonates, Valenciennes River area ...83 Lake ...... 43 43. Altered phenocrysts in a dike, Valenciennes 16. Phlogopite in carbonatite, from Verity ...... 46 River area ...... 83 17. Welllayered carbonatite, Howard Creek ...... 46 44. Sharp contact between breccia phases, HP pipe...... 85 18. Migmatitic lencosomein layered syenites, 45. Large gabbroicxenolith in a strongly foliated Paradise Lake...... pipe47 breccia, HP ...... 85 19. Migmatitic segregations of coarse perthite 46. Optically zoned andradite garnets, HP pipe...... 85 crystals in layered nepheline syenite gneiss, 47. Biotite macrocryst coring accretionary lapilli, Paradise Lake 47 Lake Paradise ...... pipe HP ...... 85 20. Coarse-grained ilmenite segregation in 48. Graded bedding in extrusive epiclastic layer, leucosyenite,Mountain Trident pipe ...... 51 Joff ...... 91 21. Typicalbanded nephelinesyenites, Trident 49. Epiclastic crater-infill breccia, Joff pipe, Mountain ...... 51 immediately overlain by well-bedded, pink and 22. Leucosyenite dikes cutting mafic, biotite-amphibole buff-weathering strata of the basal Devonian unit .....92 gneiss, Trident Mountain ...... 52 50. Well-bedded crater-infill material, Russell Peak 23. Xenolith of mafic gneiss in biotite-rich syenite, diatreme ...... 93 Trident Mountain...... 52 51. Porphyritic volcanic rock, Russell Peak diatreme..... 93

- vi Geological Survey Bnznch Minisfry of Energy, Mines and Petroleum

52. Vesiculated glass lapilli in diatreme breccia, APPENDICES Quinn Creek...... 94 1. Rare-earth element analysesfrom some carbonatite 53. Pillowed flow, Swansou Peak...... 96 suites ...... x27 54. Chrome spine1 macrocryst, Summer diatreme 2. (A) U-Pb zircon data, British Columbia breccia ...... 97 carhnatites and nephelinesyenites ...... 128 55. Pyroxenite inclusion forming the core of an (B) Uranium-lead analytical data, accretionary lapillus, central breccia phase, Cross B.C. diatrernes ...... 129 kimberlite ...... 102 (C) Summary of RblSr analytical data, 56. Altered olivine macrocrysts andphenocrysts, B.C. diatremes ...... :I30 phlogopite phenocrysts and opaque oxidesin a (D)Summary of K-Ar analytical data, magmatic matrix, Cross kimberlite ...... 102 B.C. diatremes ...... ~131

Bulletin 88 vii ~.

British Columbia -

viii Geological Survey Bn Ministry of Energy, Mines and Petroleum Resources "

INTRODUCTION

A previously poorly documented alkaline igneous may contain diamond, but only as a rare constihtent. 'he province is present in the Canadian Cordillera. It comprises term kimberlite was introduced intothe geological literature carbonatites, nepheline and sodalite syenites, some ijolite- in 1887 to describe the hostrocks of diamonds at Kimberley, series rocks, one kimberlite locality and numerous ul- South Africa. Since that time many rocks carrying oli- tramafic and lamprophyric diatremebreccias, all of which intruded the Cordilleran miogeoclinal succession prior to vine+phlogopite+carbonat&clinopyroxene+feldspathoid+ the deformation and metamorphism associated with the spinel have erroneously been referred to as kinberlites, Jura-Cretaceous Columbianorogeny. rocks which should be placed in the 1amprophSre group Carbonatites are ultrabasic igneous rockscomposed of (Clement etal., 1984). Inaccurate orincorrectclasrification more than 50% carbonate minerals. They may contain sig- only complicatesthe understandingof petrogenetic:and eco- nificant amounts of olivine, magnetite, pyroxene, sodic am- nomic implications. phibole, biotite, vermiculite, apatite, columbite, zircon, Kimberlite has traditionally heeu considered the only rare-earth minerals andpyrochlore. Carbonatites occur most important primary source of diamond. Recent studies commonly as intrusive bodies, generally associated with (Scott-Smith and Skinner, 1984a, 1984b; Jacques et al., other alkalineigneous rocks(Pecora, 1956; Heinrich, 1966) 1986; Scott-Smith et al., 1986) have shown that diamonds such as nepheline syenites, ijolites, urtites, melteigites may also be present in economic concentrations in lamproi- (nepheline+maficsilicateskfeldspathoidsinvariouspropor- tions) and jacupirangites (alkaline pyroxenites). Metaso- tes. Lamproites are ultrapotassic rocks that are chemically matic rocks (fenites), which are generally enriched in andmineralogically distinct fromkimberlites. characterized sodium andferric iron and depleted in silica, are also com- by thepresence of phenocrystic and/or groundmass leucite, monly associated with carbonatites, often marginal to the titanium-rich phlogopite, clinopyroxene, amphihole (!.ita- intrusive complexes. Extrusive carbonatites are less com- nium and potassium-rich richterite), olivine and !;anidinert mon, buthavebeen describedin westemUganda (von Knor- glass (Scott-Smith and Skinner, 1984b).Diamonds; have oc- ring and du Bois, 1961). northern Tanzania (Dawson, 1962, casionally been reported from carbonatites and pt:ridotites, 1964, Hay, 1983). Kenya(Le Bas andDixon, 1965; Le Bas, 1977; Deans and Roberts, 1984) and Germany (Keller, but, to date, the only known economic primarysources re- 1981). main kimberlites and lamproites. Diatreme breccia pipes in Many cabonatite bodies are valuable sourcesof a num- British Columbia havebeen targetsfor diamond exploration ber of commodities. Niobium hasbeen producedat Oka and since the mid-1970s (Grieve, 1981; Dummett et tzl., 1985) St. Honor&, Quebec andat Araxa, Brazil; the Mountain Pass even though mostare nottrue kimberlites; microdiamonds carbonatite in California is the largest producer of rare-earth have been discovered in heavy mineralseparates from two elements in the westem world; and copper and byproduct of these pipes (Dummett et al., 1985). Diamondr are also apatite, magnetite, vermiculite and zirconium oxide are pro- known to occur in kimberlites from the Colorado-Wyoming duced at Palabora, South Africa (Heinrich, 1966; Currie, State-Line district (McCallum and Marbarak,1976), from 1976a). Nepheline syenite is an important rawmaterial used the Mountain diatreme in Yukon (Godwin andPrice, 1987) in the glass and ceramics industries. Small amounts have and from placer deposits in Alaska (Forbes et also been usedin paints and as fillers in plastics. The Blue d,1987) Mountain regionof Ontario is the largest western world pro- where stones over 1 carat in size have been recovered. ducer of nepheline syenite (Cume, 1976a). Since the 1950s The parental magmas of alkaline igneous rocks are a number of carbonatite complexes in British Columbia meltswhichformdeepinthemant1e.Thesemeltsc~ostcom- have been prospected for various commodities at different monly intrude cratonic or 'shield' areas with a longhistory times; their vermiculite, niobium, zirconium and rare-earth of tectonic stability (Heinrich, 1966; Dawson, 1980) and potential has been explored. None haveany history ofpro- their emplacementis often indirectly associated with normal duction. faults, grabens or failed rifts. In British Columbia, the car- Kimberlites arevolatile-rich, potassic, ultrabasic igne- bonatites and related rocks wereintruded into the sedinlen- ous rocks which occur as small volcanic pipes, dikes and sills. They have adistinctly inequigranular texture resulting tary prism deposited along the rifted continental margin, from the presenceof macrocrysts (olivinefphlogopite, pi- making this a somewhat anomalousalkaline province in a croilmenite, chrome spinel, magnesian garnet, clinopy- structural setting which differsfrommostothers worldwide. roxene and orthopyroxene)set in a fine-grained matrix. The Consequently, thissuite has importantimplications because matrix contains phenocrystic and/or groundmass it documents the characteristics of carhonatites and related olivinefphlogopite, carbonate, serpentine, clinopyroxene rocks emplaced in a continental margin environ~nent, and andmany otherminerals (Clementetal.,1984). Kimberlites details the subsequent effects of orogenesis.

" Bullefin 88 I DISTRIBUTION AND GENERAL Rocky Mountain Trench; the eastern edge of the Omineca CHARACTERISTICS OF Belt; and in the vicinity of Frenchman Cap dome, a core gneiss complex, also within the Omineca Belt. The eaiitern CARBONATITES AND NEPHELINE or Foreland Belt (Figure 1) hosts carbonatites and dated SYENITES rocks within Paleozoic strata, predominantly in the Main and Western ranges the Rocky Mountains. Thisbelt con- In British Columbia, carbonatites, nepheline and so- of tains the Aley carbonatite complex (Mader, 1986, 1!)87), dalite syenite gneisses and related alkaline rocks are found Wicheeda Lake showing (Prince and George claims, Bet- in a broad zone whichis parallel to, and on either side of the Rocky Mountain Trench. Carbonatitesand relatedrocks are manis, 1987; Maderand Greenwood, 1988),BearpawRidge sodalite syenite, the Ice River syenite and carbonatite corn- also reported from anumber of areas in the western United the Rock Canyon Creek fluo- States, for example, the McClure Mountain,Iron Hill, Gem plex (Cnrrie,1975,1976a) and rite and rare-earth showing, a carbonatite-related deposit Park and Wet Mountain areas of Colorado (Lmen, 1942; Olson and Wallace, 1956; Parker and Sharp, 1970; Nash, (Hora andKwong, 1986). The Aley, Ice River andBearpaw 1972; Hildebrand and Conklin, 1974; Armbrustmacher, Ridge intrusions are subcircular to elliptical in plan, gcner- ally have extensive metasomatic alteration or contact meta- 1979, 1984; Armbrustmacher et al., 1979), the Lemitar morphic halos and are hosted by Middle Cambrir.n to Mountains, central New Mexico (McLemore, 1987) andthe Mountain Pass area, California-Nevada State-Line (Olson Middle Devonian miogeoclinalrocks. Alkalic rocks i:1the etal., 1954; Jaffe, 1955; Warhol, 1980; Woyski, 1980). Wicheeda Lake area define a linear zone, and consist of small plugs, dikes and sills. The Rock Canyon Creekshow- Three discrete areas hosting carbonatites can be defined ing is an elongate zone of fluorite and rare-earth metaso- within British Columbia: the Foreland Belt, east of the matic alteration in Devonian carbonate rocks, possibly

Figure 1. Index map, carbonatite and nepheline syenite gneiss complexes.

2 Geological Survey Bxanck ~~ ______~ ~~~ ~~ ~ related to a buriedcarbonatite. Carbonatites in this belt ex- syenite gneiss (Fyles, 1970;Cnme, 1976b) occursalong the hibit varied mineralogy andare enriched in niobium, fluo- southern margin of the gneiss dome. The extrusive Mount rine and rare-earth elements relative to other British Grace carbonatite tuff, intrusive carbonatites with thick Columbia occurrences. During the Colnmbian orogeny the fenitited margins and syenite gneisses occur along the intrusions were subjected to sub-greenschist to greenschist northern and westernflanks of the dome. Bothof .he inm- facies metamorphism. The obviouseffects of deformation sive andextrusive carbonatites are moderately enrichedin are minor, the intrusions appear to have behaved as rigid rare-earth elements, but no significant niobium mineraliza- bodies during orogenesis and were simply rotated, tilted tion has beenreported. and/or transported eastwards in thrust slices. Locally, small Several tens of kilometres to the south of tht: French- faults cut the alkalic rocks. man Cap Dome, near ThreeValley Gap, anothercarbonatite The Kechika River complexis located a few kilometres is hosted bymigmatitic gneisses of uncertain affinity. It ex- west of the Rocky Mountain Trench, in the Cassiar Moun- hibits many similarities in fieldrelationships and geochemi- tains (Fox, 1987; Pell et al., 1989). It is morphologically cal signatures to the intrusions of the Blue River and similar to the Wicheeda Lake showing,consisting of dikes Manson Creek areas along the eastern margin of the and plugs and probable pyroclastic layers distributed in a Omineca Belt. linear belt. Although notin the Rocky Mountains,it exhibits many similarities to alkalic rocks in the Foreland Belt and DISTRIBUTION AND GENERAL for the purposes of this discussion, will be consideredwith CHARACTERISTICS OF KIMBERLITES them. AND ALKALINE ULTRABASIC Carbonatites and syenites are found along the eastern DIATREME BRECCIAS margin of the Omineca Belt, extending westward from the Rocky Mountain Trench for 50 kilometres or more. All the Alkaline ultrabasic diatremes anddikes have been dis- intrusions within this belt are hosted by late Precambrian covered in the Western and Mainranges of the Rocky Moun- (Upper Proterozoic) to Early Cambrian metasedimentary tains and in the Cassiar Mountains of British Columbia rocks. They generally form foliated, sill-like bodies that (Figure 2). With the exception of the Cross diatrenle, all are have been multiply deformed and metamorphosed to am- hosted byCambrian to Silurian miogeoclinalrocks (Roberts pbibolite facies during the middle Mesozoic orogeny; some et al., 1980; Grieve, 1981; Pell, 1986~.1987b). The Cross small plugs anddiscordant dikes are also present. The car- diatreme, which is located in a moreeasterly structural po- bonatites have thin sodic pyroxene and amphibole-richfeni- sition, is hosted by carbonate rocksof the Pennsylvanianto tic margins. The belt comprises carbonatites associated with Permian Rocky Mountain Group (Hovdebo,195:‘; Grieve, monzonites and somesyenites in the Manson Creek area at 1985). A11 thediatremesintNdedthemiogeoclina1sequence the Lonnie and Vergil showings (Rowe, 1958; Currie, of platformal carbonate andclastic rocks prior to the Colum- 1976a). syenites and monzonites in the Mount Bisson - biau orogeny. The effects of deformation and metamor- Munroe Creekarea (Halleran, 1988; Halleran andRussell, phism are manifest in a weak to strongly dweloped 1990), carbonatites with nepheline andsodalite syenites and foliation, some flattening and the development 01: chlorite. some nrtites in the Blue River area, including the Verity, The diatremes weretransported eastwards in thnlst sheets Paradise and Howard Creeklocalities (Rowe, 1958; Cnme, during orogenesisand, therefore, have presumablybeen cut 1976a; Pell, 1987) and nepheline and sodalite syenites at off from their roots.Diatreme breccias are also fomd inthe Trident Mountain and Kinbasket Lake (Cnrrie, 1976a; MackenzieMountains, Yukon (Mountaindiatremc:, Godwin Perkins, 1983). No carbonatites in this zone are known to and Price 1987; Coates Lake diatreme, C. Jeffeison, per- contain potentially economic concentrations of niobium or sonalcommunication, 1987); kimberlites andrelatedalkalic rare-earth elements; however, pegmatites dramatically en- ultramafic diatremes have been found in north-central Mon- riched in light rare-earth element havebeen reported from tana (Hearn, 1968; Hearn and McGee, 1983); kimberlites the Mount Bissonarea (Halleran and Russell, 1990). also occur in the Colorado-Wyoming State-Lin: District The most westerlyarea contains intrusive and extrusive (e.g. Sloanpipe,HauseletaL, 1979,1981;McCal:umeraZ., carhonatites and syenite gneiss bodies in a mixed paragneiss 1975; McCallum and Marbarak,1976). succession along themargins of the Frenchman Capgneiss Ultrabasic diatremes are present in five geographic: re- domenorth ofRevelstoke(Wheeler, 1965;McNlillan, 1970; gions of British Columbia. Within each area the ,diatremes McMillan and Moore, 1974; Hoy and Kwong, 1986; Hoy are, for the most part, petrologically similar. The first suite and Pell, 1986) in the core of the Omineca Bele (Figure l). is found in the Cranbrook - Bull Riverarea (Figure 2) where The Frenchman Capgneiss dome is one of several late do- examples ofcrater facies and extrusive rocks have been rec- mal structures located near the eastern margin of the ognized. The upper parts of the diatremes are chwacterized Shuswap Complex (Wheeler, 1965; Read and Brown, by bedded epiclastic and/or pyroclastic material overlying 1981). The core of the dome comprisesmixed gneisses of a chaotic fragmental breccia containing abundant vesicu- probable Aphebian age that are nnconformably overlain by lated glass lapilli. In one pipe, small mafic flowsand dikes ‘mantling gneiss’, an autochthonous cover sequencewhich are exposed nearthe top of the crater zone. These rocksare hosts the carbonatites and syenites. The intrusive and extru- porphyritic and consist of abundant clinopyroxeneand less sive alkaline rocks in this area are conformable bodiesthat abundant olivine phenocrysts, clinopyroxene, oxide andpo- were deformed and metamorphosed to upper amphibolite tassium feldspar microphenocrysts in a fine-grained facies during the Columbianorogeny. The Mount Copeland groundmass. Deeper levels within the craters are charac-

Bulletin 88 3 terized by juvenile lapilli-rich breccias with rare macro- (1986). These diatremes and dikes are associated with crysts of chrome spinel, altered pyroxenes andaltered oli- quartzxenocryst rich breccias,containingsedimentaryarylock vines sporadically distributed throughout. Micas are not fragments and little recognizable igneous material. Mi- present in these rocks. Sedimentaryrock fragments, granitic crodiamonds have reportedly been recovered from hc:avy clasts and a variety ofpyroxenite andperiodotite xenoliths mineral separates taken from two pipes of this type (Dum- have been recovered from these pipes. Tentatively, these mett etal., 1985). rocks areinterpreted to have an alkaline lamprophyre affin- In a third area, near Williston Lake and the Os:?ika ity. River, northern Rocky Mountains, a single pipe has ken The secondsuite, found north of Golden (Figure 2). is discovered near the Aley carbonatite complex. It exhibits characterized by macrocryst-rich breccias and dikes. The many similarities to the pipes inthe Golden area; it is a ~nnl- macrocryst population consists of titaniferous augite or tiphase diatreme characterized by macrocrystic green salite, phlogopite, green chrome diopside, spinel and rare chrome pyroxene,augite, pholgopite and spinel. Basei on olivine, with either clinopyroxeneor phlogopite most abnn- mineralogy it can be classified as an aillikite, a type of ul- dant (Ijewliw, 1987;Pell 1987a). Sedimentary fragmentsare trabasic lamprophyre. predominant in the breccias; gabbroic and granitic xeno- A diatreme breccia and related dikes are also known in liths, as well as cognate material, spherical structnres and the Kechika area of the Cassiar Mountainsin northern :Brit- nucleated autoliths are also present locally. These pipes are ish Columbia. Thesebreccias are richin juvenilelapilli, con- multiphase intrusions, with massive and multiple breccia tain abundant sedimentary rock fragments, rare chrome phases cut by related dikes. Petrologically, the diatremes spinels and are devoid of xenocrystic micas (Pell ei' al., appear to bear someaffinity to alkaline and ultrabasic mica 1989), similar to breccias in the Cranbrook - Bull Piver lamprophyres (alnoites and aillikites) as defined by Rock area.

Figure 2. Index map, alkaline ultrabasic diafxemeswarms (from Pelf, 1987). For details on the Ospika Pipe see Figure 3 or Miider ( 1987).

4 Geofogical SunqE'ranch Ministry of Energy, Mines andPetroleum lEc3

The last geographically andpetrologically distinct rock All the carbonatite-syenite localities (with the exception of typeis represented by one example,the Cross diatreme, lo- theWicheedaLakeandMountBissonshowings,di:rcove:red cated at Crossing Creek, north of the town of Elkford. To late in the project) and alarge number ofthe diatreme brec- date, this breccia pipe is the only true kimberlite recognized cias were mapped and sampled. The purposeof tllis study in the southern Canadian Cordillera (Grieve, 1981, 1982; is to document alkaline rock occurrences in British Colm- Hall e#al., 1986; Ijewliw, 1986,1987). It is a multiple intru- bia; to describe their petrography, geochemistry, economic sion with massive andbreccia phases containing xenoliths geology andfield relationships; and to determine the timing of garnet and spinel lherzolite, serpentinized peridotite, and tectonic controls of emplacement, providing basis a for gimmerite and sedimentary material as well as pelletal future, detailed studies. Most new work concenmted on lapilli and xenocrystsof olivine, pyrope garnet, spinel and previously undocumented occurrences; previous1:r studied phlogopite. Massive phases have a magmatic matrixof ser- suites were examinedfor comparison purposes. pentine, carbonate, microphenocrystic olivine and spinels. No diamonds havebeen reported from this pipe. The ratio of ultramafic to sedimentary xenoliths is greater in the Cross ACKNOWLEDGMENTS diatreme than in anyof the other breccia pipes andit is characteristic of the diatreme facies of kimberlites (Hawthorne, The Canadaritish Columbia Mineral Development 1978; Clement andReid, 1986). Agreement 1985-1990 has provided the financial support which made this project possible; the Natural Sciences and GEOLOGICALWORK Engineering Research Council of Canada supplied addi- Prior to this study, documentation of carbonatites, tional funding. R.L. Armstrong, The University of British syenite gneisses and alkaline ultramafic diatreme breccias Columbia, provided the rubidium-strontium dating; was limited to studies of a few complexes andbrief descrip- J. Harakal andK. Scott, The UniversityofBritish Columbia, tions of some of the others. In the Foreland Belt, the Ice the potassium-argondating; and R.Parrish, Geological Sur- River complex had beenthe subject of a number ofstudies, vey of Canada, the uranium-lead zircon dating. Neutron ac- dating back to the turn of the century (Dawson, 1885; Bar- tivation analyses were provided by Bondar-#:lege & low, 1902; Allan, 1914; Jones, 1955; Rapson, 1963; 1964). Company Ltd. The most comprehensive studyof the complex was com- I would like to thank Z.D. Hora for proposin]: the pro- pleted by Currie (1975). Other carbonatite complexes, ject in 1984 and for his continued help and ;pidance syenites, kimherlites and diatremesin the Rocky Mountains throughout; thanks also go to T. HBy, D.J. Schulze, D.C. had only receivedbrief mention in the literature. Carbona- Hall, J.A.Mott, C. Graf,B.H. Scott-Smith, C.E.Fipke,K.R. tites hosted by metamorphosedstrata along the eastern mar- Pride, U.K. Mader, H.H. Helmstaedt, D.A. Grieve, G.P.E. gin of the Omineca Belt had also received only brief White, M.Fox, R.R Culbert, A. Betmanis, B. French, !LA. mention in overview publications (Rowe, 1958; Currie, Almond, D.L. Pighin and J.K. Russell for helpfill disr:us- 1976a). Carbonatites and syenite gneisses associated with sions both in and out of the field; thanks are also extended core complexes in the Omineca Belt were discovered and to W.J. McMillan, J.M. Newel1 and B. Grant for review of studied in the course of regional mapping (Fyles, 1970; this and related manuscripts. A special thanks goesto Olga McMillan, 1970, 1973; McMillanand Moore, 1974). Sub- Ijewliw for two seasonsof capable field assistance and. for sequent studies (Currie, 1976b;HBy and Kwong, 1986; Hay, agreeing to help unravel someof the story hiddell in these 1988) providedetail on these suites. rocks, through herMaster’s thesis research. Gwen3a Loren- Work by the author was begun in 1984 and included zetti also provided capable and cheerful assistance during field mapping during the summers of1984,1985 and 1986. one field season.

Bulletin 88 5 British Columbia -

LEGEND Ro od River Group FenitizedGroupalkali-syenittRiver Rood (dolostone) amphibolite 1 >Devoniar RoodRiver Group Carbonatite (sandstone,shole) a R oad River Group Rare-earthGroup River Road (shale) carbonatitedikes SkokiFm. (dolostone,volcanics) KechikoFm. (limestone,marl, siltstone)

Figure 3. Geological mapof the Aley carbonatite complex (fromMader), 1987.

6 Geological Survey Bnznch Ministry of Energy, Mines and Petroleum .esouxes "

CARBONATITE AND SYENITE COMPLEXES IN PALEOZOIC STRATA, ROCKY AND CASSIAR MOUNTAIINS,

FORELAND BEXI'"

THE ALEY CARBONATITE COMPLEX [(Ca,Ce,Na)(Nb,Ta,Ti)2(0,OH,F)61forms fibrous to fine- grained aggregatesreplacing pyrochlore; primary fersnute (94BI9 is rare. Columbite [(Fe,Mn)(Nb,Ta)z06] is present as a re- The Aleycarbonatite complex was discoveredin 1980 placement of fersmite. and staked by Cominco Ltd. in 1982 (Pride, 1983) for its Mineral banding or layering is common, particularly niobium potential. It is located approximately 140 kilome- near the margins of the complex, and is charactmized by tres north-northwest of Mackenzie, on the east side of Wil- aligned flattened grains and aggregatesof apatite. In miner- liston Lake between the Peace Reach and the Ospika Riveralized zones, magnetite, pyrochlore, fersmite and biotite at latitude 56"27' north, longitude 123'45' west. The area is also exhibit some alignment and compositional zoning. generally above treeline (1450 - 2200 melevation) and has Field studies indicate that the mineral layering i:r steeply excellent exposure. It is fairly remote; access is by helicop- dipping and strikes approximatelyparallel to the margins of ter from Mackenzie. the complex. It has been interpreted as vertical flow band- The Aley Creek area is underlain by Cambrian to Silu- ing, a primary igneous texture (Mader, 1986) as is observed rian carbonate andclastic rocks of the Kechika, Skoki and in many other carbonatite complexes (e.g., Oka). Road River groups (Thompson, 1978; Pride, 1983). This miogeoclinal succession, deposited near the outer edge of SOVITE ZONES the continental shelf, was intruded by the Aley carbonatite Sovite zones (dikes and 'sweats') occur locally near the complex prior to the main Late Jurassic to Early Cretaceous margin of the rauhaugite core zone andin the sunaunding orogenic event. The youngestunit affected by the intrusion amphibolite zone. The sovites exhibit a more variable minis the mid-Ordovician(?) Skokivolcanic sequence. Much of eralogy than the rauhaugites. Calcite with or without dalo- the followingdescription of the carbonatite complex is sum- mite dominates (40.95%) and there are accessory to major marized fromthe work of Mader (1986,1987). amounts of apatite (2-lo%), biotite (0-5%),magnetite (0 to The complexis oval in outline with a diameter of 3 to 40%), richterite, a sodic amphibole (0-5%), pyrochlore (O- 3.5 kilometres, occupying anarea of approximately 7 square 2%). fersmite and pyrite (Pride et al., 1986). Zirconand rare kilometres. It is cylindrical, with a near-vertical axis and baddeleyite associated with zirkelite have also been re- consists of a rauhaugite (dolomitic carbonatite) core zone ported; mineral bandingis well developed. surrounded by an older, outer ring of amphibolite. Some sovite (calcitic carbonatite) and rare-earth carbonate 'AMPHIBOLITIC'MARGIN 'sweats' occur in the rauhaugite core. A contact aureole of An 'amphibolitic' margin, approximately 1 kilometre recrystallized carbonate rocks surrounds the amphibolite in width, encircles and complexly interfngers with the margin. Rare-earth-enriched carbonatite dikes intrude the rauhaugite core. The marginal zone includes massive and contact aureole (Figure 3). Ultrabasic lamprophyre dikes breccia phases. No distinct pattern to the spatial dis ribution and a diatreme breccia pipe (Ospika pipe) intrude altered of the two phases is evident. Carbonatite dikes cut both and fresh carbonates outside the complex. These will be dis- members, indicating the 'amphibolite' margin pred %ted em- cussed later in this report. placement of the carbonatite core zone. The massive phaseis a medium to coarse-grained, dark RAUHAUGITE CORE ZONE green rock consisting primarily of sodic amphibole (mag- The coreof the Aley complex is approximately 2kilo- nesio-arfvedsonite), quartz, albite and aegirine. It is more metres in diameter. It comprises morethan 50% of the ex- extensively developed than the breccia phase and resembles posed complex and consists of dolomite (80.99%) and fenites associated with some of the other carhonatite com- apatite (1-10%) witb minor amounts of phlogopite, pyrite, plexes in British Columbia. Mader (1986,1987)h2.s recog- magnetite, monazite, strontianite and zircon. It is generally nized microsyenitetextures in the massive amphibolite. and a massive and homogeneous unit, weathering a buff to suggests that it is a primary igneous phase with a metaso- brownish colour. Pyrochlore [(Na,Ca,Ce)2 (Nb,Ta,Ti)z Os matic (fenitic) overprint, as opposed to fenitized country (OH,F)] may be present in this zone. Fersmite rock. This appearsto be the most reasonableinterpretation

Bulletin 88 7 -~~

British Columbia -

for the origin of this rock; however, the true nature of the primary igneous phaseis so obscured that classificatim is difficult. The breccia phase contains subrounded clasts of dominantly orthoquartzite, with some siltstone, albitite and microsyenite fragments in a matrix that is similar to the massive phase andlocally grades into it. The clast-to-natrix ratio is highly variable and clast-supported breccias ate developed locally; on average, clasts comprise l to 30%of the rock volume. Their subrounded nature gives this unit the appearanceof a conglomerate(Plates 1 and 2). The quartzite and siltstone xenoliths range from afew milliietres lo approximately 30 centimetres in diameter. Reaction rims consisting predominantly of fine-grained aegirine commonly envelop the xenoliths. The quartzite xenoliths are probably derived from Lower Cambrianquartzite formations which the complex must have sampled during itsascent. Niicro-

syenite and albitite clasts may represent deeper level 'mtru- sives or fenites associated with the original magma chanber. The extreme roundnessof clasts is similar to many of the diatremebreccias and may be a result of gas-streamingabra- sion.

ALTERATION HALO Sedimentary rocksadjacent to the Aley complex have been altered for a distance of approximately500 metn:s be- Plate 1. Rounded xenolithsof quartzite and syenite in the breccia yond the 'amphibolite' margin. This alteration halo is char- phase of the "amphibolitic" margin, Aley complex. acterized by a colour change fromgreyish to a distinct buff hue. The altered rocks may superficially resemble mzlterial

Plate 2. Roundedquartzite xenoliths weathering out of the Plate 3. Chocolatebrown-weathering, REE-enriched dikes in "amphibolite" margin, Aley complex. carbonate hostrocks, Aley complex, (colourphoto, page,'35).

8 Geological Survey Branch TABLE 1 CHEMICAL ANALYSES, ALEY CARBONATITE COMPLEX

0.50 0.28 0.52 1.08 0.69 5.80 2.42 7.22 2.17 3.84 3.53 1.67 1.02 0.65 7.30 0.56 2.31 0.80 0.4066.36 75.15 53.W 60.17 44.W 20.41 7.93 4.01 4.01 0.01 0.72 0.18 020 0.20 0.14 0.02 0.10 0.08 0.02 0.03 0.01 0.04 0.02 0.01 0.00 0.01 0.68 0.41 1.310.35 0.150.15 0.41 0.26 0.14 0.16 0.12 0.49 0.34 0.15 0.30 0.02 0.03 0.51 0.24 0.18 0.21 0.67 0.49 0.08 0.04 6.391.338.304.280.12 0.081.738.69 16.50 - 2.504.91 5.48 265 2.29 4.34 13.68 3.59 1.80 - - 5.82 3.94 5.33 11.105.61 - 12.9110.98 4.362.5419.92 2.95 108 0.76 1.92 . . - .. - 8.4110.49 - 3.88 . - .. 0.26 0.87 0.77 0.25 0.22 0.900.22 0.22 ND ND ND 0.23 0.40 3.304.11 1.58 1.37 1.66 0.450.350.140.272.68 1.370.49 044 0.17 17.3416.68 14.79 18.02 16.5016.60 14.90 12.77 7.715.85 2.92 2.M) 1.80 7.9111.29 13.48 14.77 13.74 13.072.550.8716.W 3.61 5.223.729.18 1.66 32.8934.82 34.2933.71 31.20 28.20 31.W 32.74 15.6941.47 41.34 45.50 46.W 28.1424.59 n.73 30.44 29.39 3.9828.183.502.284.05 14.8035.88 25.32 4.59 0.63 0.080.63 NDND 0.06 0.050.08 0.W 0.48 0.46 0.18 0.08 0.12 0.791.13 0.10 ND ND ND 8.727.713.857.79 2.833.83 0.04 8.86 0.02 0.010.02 0.02 0.01 4.10 026 0.13 0.02 0.050.13 0.03 0.11 0.13 0.060.04 0.02 ND ND ND 1.153.680.24 020 0.030.523.10 0.37

43.5242.00 40.16 41.96 36.46 39.96 37.08 27.86 38.7236.0630.20 35.36 39.69 142.55 33-11 - 40.3841.0841.42 1 0.841-16 - . 15.45 2639 20.02 5.16 1.74xp~8:69. ~3.15 6.07 1.81 5.29 11.42 0.14 0.09 0.34- 0.60 0.90 0.52 0.70 0.20 0.68 0.60 9.133.230.45 00.11- 97.32101.33 99.78 97.35 99.03 93.97 95.34 93.9092.94 92.01 98.86 99.92 %98 96.411W.54 98.77 92.50 I - <2 c2 5 IO .. c2 .. 7 14 c2 - CZO c20 E20 c20 .. < 20 .. 36 <20 c 20 - 10 4 10 I1 .. 12 .. - 15 C5 359 4377 44493391831457 1426 2023 5281 4630 686 3506 141 670 - 3663 642 2023 85 33 45 5939 451% 33 85 24 38 314 248 308 323 I84 540 461 1665 - 450 66 46535 146 497 499 70 290 M)4 559 308 563 887 390 40 79 290 490 168 17961384 5699 683 6759 13525 3290 4610 5M0 891 n 280 10 803119 5697 41 1418 140 122 69 249 138 97 93 122 129 18 21 48 227 138 310 142205 388 355 322 598 558 314 248 308 307 70468725 63 2789 60 235 . 813 loul 379 750 224 909 11151215390816 856 708 82 1318 590 l2lW 125W 4ooo 170 110143 . 1260 2070 905 210 59 310 297 - . - ND ND ND 2940 326056 1080 46 - 941 .. ." .. 11.6 10.0 3.5 - .. - 21 - 33 28 41 36 .. 46 26 2.6 1.7 - .. 32 5.6 31 18 ND 17 166 1 <2 c2 171 <20 c20 59 230 c2 <2 <2 - " Q 53 579 130 ND 21 184 375 5 23 712 65 106 464 253 151 105 61 <7 <7

Figure 5. Chondrite-normalized rare-earth element plots- Aley.

Figure 4. Major element ternary plots of carbonatites and Figure 6. Ternary plots for fenites, Aley;Figure 6a after Hay, 88; "amphibolitic" margin.Aley; Plot 4b after Wooley, 1982. Figure 6b after Le Bas, 1981.

10 Geological Survey Bra1 Ministry of Energy, Mines and Petroleum Resortrues from the rauhaugite corezone. Apatite,pyrite and magnetite 339f12 Ma and 349k12 Ma. The data suggest an age of are locally developed in the alteration zone. Silicification emplacement inlatest Devonianto early Mississippiantime. and development of green amphibole occursimmediately adjacent to the contact (10-40 cm). White mica and potas- WICHEEDA LAKE COMPLEX (PRINCE sium feldspar are the only commonmetamorphic minerals observed in impure marles, mark and siltstones and the de- AND GEORGE CLAIMS, 931/5; 93J/lt, 9) gree of alteration decreases outward from the complex. A series of carbonatite plugs, sills and dikes, mociated Trace element abnudances(Nb, REE, Th, F) can be corre- with alkaline silicate rocks, are located on the Prince and lated with the degree of alteration, also decreasing outward. George claims near Wicheeda Lake, approximately 80 kilometres northeast of Prince George (latitude 54”3:1’N, RARE-EARTH-BEARING DIKES longitude 122%4W; Figure1). Access to the area is by heli- Dikes or ‘sweats’ enriched in rare-earthelements (REE) copter. Elevations range from 820to 1490 metre:;, and the occur throughoutthe complex but are most common in the area is largely forested. Outcrops are limited to ridge tops outer alteration halo. The dikes weather adistinct, dark red- and some rock bluffs. The claims were stakedin 1986 by dish brown (Plate 3). are generally intruded parallel to bed- TeckExplorations Limitedwhen anomalousniobium valnes ding and average 0.5 to 1.5 metres in thickness. Their were detected in samples previously collected from a minor primary componentis ankerite. Accessory mineralsinclude base metal showing. purple fluorite, quartz, pyrite, barite, bastnaesite The alkaline rocks intrude northwest-striking, steeply [(Ce,La)C03F] and other rare-earth carbonate minerals to subvertically dipping dolostones, limestones 2nd argil- (K.R. Pride and U.K. Mader, personal communications, laceous rocks of uncertain age. The Wicheeda Lake area 1986). Rare-earth carbonate mineralsare fine grained, com- straddles the boundary of two map sheets, mapped by dif- monly intergrown and comprise 3 to 6% of the rock. ferent workers (Armstrong et al., 1969; Taylor and Stott, 1979) and lithologic formations do not correlate across the GEOCHEMISTRY map-sheet boundaries. Onone mapsheet (Armstrcng et al., 1969), strata which host the alkaline rocks are as:;igned to Carbonatites, both rauhaugites and sovites, are very the UpperCambrian Kechika Group, which is in thrust con- low insilica, aluminum and alkalis, and high in phosphorus, tact, to the southwest of the property, withLower Cambrian up to 11.42% P2O5 (Table1). Calcite carbonatites predomi- clastic rocks of the Misinchinka Group. Taylor 2nd Stott nantly plot within the sovite field on a CaO-MgO- (1979) correlate strata hosting the carbonatites with the Fe203+FeO+MnO carbonatite diagram, dolomitic carbonatites within the magnesio-carbonatitefield and rare- earth-enriched dikes span the magnesio- to ferrocarbonatite boundary (Figure 4h). All are enriched in the incompatible elements thorium, niobium, zirconium light and rare earths. Extensive zones within the rauhaugite corecontaining between two-thirds and three-quarters of a percent niobium have been defined, and local concentrations of over 2% Nb2os are present (K.R. Pride, personat communication, 1987). Barium, strontiumand total rare-earth elements may reach major element concentrations of 7.74, 0.5 and approximately 2%, respectively (Table 1 and Appendix 1) in the rare-earth- bearing dikes. Cerium is the dominantrare- earth element present; lanthanum and neodymium are also abundant. Fluorine, manganese, barium and, to a lesser extent, iron are also enriched in the dikes relative to rauhaugites and sovites, while niobium andtantalum are depleted. The ‘amphibolitic’ margin has variable major element concentrations (Table 1 and Figures 4and 5) and trace element patterns similar to typical carbonatites, but with much lower concentrations. It is compositionally different from ‘typical’ pyroxene-amphibolefenites in that it contains significantly more sodium and potassium (Figure 6), which carbonatite plug may be a result of its original alkaline igneous or syenitic alkaline dikes > GEORGE GRID composition. ggg soil anomaly (NE), some LAKE GRIC exposedcorbonatiie and

~~ I syenite ~~ ~~ GEOCHRONOLOGY I Figure 7. Location map of the intrusive bodiesof the Prince and Two potassium-argon dates have been obtained from George groups of claims, Wicheeda Lake from MBder and mica separates from the Aley complex (Miider, 1986), Greenwood, 1988. __ Bulletin 88 I1 .

British Columbia

Corbonatite,syenite roult ...... - - re lated rocks Contactr/:. : rocksand related

Limestone,argillaceous limestone, ~PP~OX.infered a \ InterbeddedargilliteBedding ...... / 75-85' \* pz85-90' Calcareousargillite minor ...... arglllaceouslimestone, locally Bedding, where different phyllitic from foliotion ...... 1 0 30 Nodularargillite, massive Minerallayering in locallycalcareous intrusive rocks ...... -- -Metres l 0 =Layered calcitecarbonatit< (K-feldspar,aegirine. sphene, biotite) 0 t ILeuco- to merotvDe Ieucii

Figure 8. Geological mapof the southwesternpart of the Prince grid (enlargement) from Mader and Greenwood, 1988.

12 Geological Survey Bronch ~~~~ ~~

Ministry of Energy, Mines and Pefmleum Resources

Lower Ordovician Chushina and MiddleOrdovician Skoki A third carbonatite body is poorly exposed west of the formations, overthrust by Precambrian Misinchinka Group southern end of WicheedaLake (Lakegrid; Betmanis, 1987; metasedimentary rocks. The following descriptions of the Mader and Greenwood,1988). It consists of sovite with ac- complex are summarized from the work of Mader and cessory apatite, feldspar, aegirine and, locally, coarse (0.1 Greenwood (1988). to 0.8 millimetre) enhedral pyrochlorecrystals. Sane sam- The carbonatite sills, plugs anddikes are distributed in ples collected from this area contained slightly in excess of a northwest-sttiking linear zone in excess of 8 kilometres 1% total rare earths (Betmanis, 1988). long (Figure 7). All the intrusions show mineralogy typical of igneous alkaline rocks, but eachstock has distinctive pet- ALKALINE DIKES rographic features. As a whole, thesuite is characterized by Three varieties of alkaline dikes are present peripheral the ubiquitous presence of ilmenite and sodic pyroxene. to the ankeritic carbonatite plug south-southeast of Carbonatites range from almostpure sovites to pyroxene- Wicheeda Lake. They are quite thin (50-150 cm) and biotite-rich varieties to rare-earth-rich ferrocarbonatites. slightly discordant to bedding and schistosity. The first type Silicate rocks include syenites and leucitites rich in albite is a potassium feldspar porphyry with a fine-grai:ned and potassium feldspar. Most of the rocks are medium groundmasscontaining albite, biotite and accessoly calcite, grained andoften display mineral Iayering. In all cases, ther- ilmenite and zircon. The second type comprises abundant mal and metasomatic effects on country rocks are appar- blue sodalite phenocrysts in a fine-grained groundmas:$ of ently minimal. albite and sodalite with accessory calcite, ilmenite, sphalerite and zircon. Rare xenoliths of microsyenite are also present. A third type of dike, which cuts the scdalite- CARBONATITES AND ASSOCIATED SYENITIC rich dikes, consists of an intermediate feldspar augite por- ROCKS phyry with an aphanitic groundmass. A sill complex has been traced for carbonatite-syenite GEOCHEMISTRY nearly 3 kilometres alongstrike on thesoutheastern part of the property (Prince grid; Betmanis, 1987; Mader and Whole-rock geochemical data are not available for Greenwood, 1988).Approximately halfway alongitslength samples fromthe Wicheeda Lakearea. Limited data indicate the sill is cut by a northerly striking fault (Figure 8) and that the intrusive rocks are enriched in elements typical. of lithologies to the northwest of the fault differ from those to alkaline rocks and carbonatite comdexes (ex.._ NI. ..Ba, Sr. the southeast. Southeast of the fault, where the sill is the ~~~ ~~ ~~ thickest, white, layered sovite intrudes coarse-grained leu- CHONDRITE-NORMALIZED REE PLOT WICHEEDALAKE ALKALINE COMPLEX cosyenite, augite-leucite-syenite and layered, fine-grained augite-syenite. All rock types arerich in sphene. Northwest ‘OS3 of the fault, medium to coarse-grained sovites which contain feldspars, aegirine, biotite, pyrite, apatite and pyrochlore are #+ Rare-earth elemmi present. These rocksexhibit a pronouncedmineral layering enriched dike and are intercalated with syenites rich in albite and potas- 104 sium feldspar and also contain aegirine and biotite. Contacts between carbonate andsilicate rocks are locally either distinct or gradational. Locally, analyses of nearly 1% Nb205 were returned from samples taken treuches from in this area (Betmanis, 1987). An oval carbonatite plug, approximately 250metres in diameter, is exposed south-southeast of Wicbeeda Lake (Figure 7) on the northwestern part of the property (George grid; Betmanis, 1987; Mader and Greenwood,1988). The intrusion is predominantly anankeritic carbonatite, locally containing ankerite phenocrysts up to 5 centimetres long and pyrite cubes which reach 2 centimetres across. Potas- sium feldspar, ilmenite, monazite andrare-earth carbonate minerals are present as minor constituents. Along the southwestern margin ofthe plug, albite-rich rocks are intermixed with ilmenite-rich carbonatite. Some rare-earth mineralization is hosted by this carhonatite. Samples fromone trench, 42 metres long, averaged 2.60% total rare-earth elements, including a shorter sample interval of over 4% total rare 1 1,~11~~111,,1~,11,111111,1 earths (Betmanis, 1988). Soils in the vicinity also contain Lo Ce Pr Nd Sm Eu Tb Dy Ha Tm Ib Lu high rare-earth concentrations, with one sample containing Rare-earthElements over 4%total rare earths (Betmanis, 1987). The majority of Figure9.ChondritenormalizedREEplot-WicheedaLakealkaliae these values are concentrated in the light rare earths. complex. REE). Rare-earth element analyses (Betmanis, 1987;sum- 54”03’00”N, longitude 12lo35’30”E). The ridge reaches a marized in Appendix 1) indicate that these rocks are en- maximum elevation of 1700 metresin this area and is largely riched in light rare earths; chondrite-normalized plots forested. Best exposureis found in subalpine meadowson (Figure 9) display patterns typical of other alkaline intru- north-facing slopes. The lowerslopes are easily reachzd by sions in British Columbia. logging roads from McGregor and Prince George;to accms the ridge crest is on foot or by helicopter. GEOCHRONOLOGY The syenite intrudes Silurian Nonda Formation vol- No radiometricdate has been obtainedon the Wicheeda caniclastic rocks (Figure lo), which are predominantly al- Lake rocks. Due to lack of outcrop, unambiguous field re- kaline mafic tuffs, locally containing limestone clasts. lationships are not exposed. The intrusive rocks display Regionally, the hostrocks have attained lower greenxhist well-developed fabrics in thin section and outcropthat are facies metamorphism; however,biotite is present in thf: vol- concordant with the regional schistosity. They are, there- canics immediately adjacent to the sodalite syenite. The fore, interpreted as having been intruded prior to the Colum- syenite is massive, medium grained and whiteweathering. bian orogeny and, together with their host strata. were Three apparently separate bodies crop out; oval stock, subsequently deformed during orogenesis (Mader and an Greenwood, 1988). 500 metres by loo0 metres in area,is flanked by two smaller sill-like bodies (Figure IO). The stock contains rand,mly BEARPAW RIDGE SODALITE SYENITE oriented feldspar laths (1-5 centimetres long) with inemti- tial mafic silicate, feldspathoid and opaque minerals. The (9W) sills have feldspar phenocrysts upto 4 centimetres lorg, in Abody of sodalite syenite and twoflanking syenite sills a groundmassof felted feldspar laths. The main intnwions crop ont on Bearpaw Ridge in the Rocky Mountains ap- are roughly parallel to bedding in the hostrocks; how:ver, proximately 60 kilometres east of Prince George (latitude crosscutting dikelets (Plate 4) were observed.Intrusion ap-

14 Geological Survey Branch Ministry of Energy, Mines nnd Petroleum ResouKes

parently occurred prior to orogenesis. The syenites contain a low-grade metamorphic mineral assemblage(albite-epidote) and are exposedin the core of a synform. A folded andfoliated orthogneiss of unknown age crops out on the western lower slopes of Bearpaw Ridge(Figure 10). It is not shown on previous mapsof the area (lhylor and Stott, 1979) andits extent is unknown. Where exposed, the contacthetween the volcaniclastics and thegneiss isparallel to the bedding in the volcaniclastics, hut may be either depositional or faulted. A second body of syenite, also previously unmapped, crops out on the southwestern end of the ridge, intruding both the dioritic gneiss and the volcaniclastics (Figure 10). It is a massive, coarse-grained rock witha huff to pink fresh surface containing randomly oriented feldspar hths up to 1.5 centimetres long. Clinopyroxene, amphibole and opaques, predominantlymagnetite, comprise up !o 10%of the rock. This syenite appears to he postorogenic andunre- lated to the sodalite syenite on the ridge crest. It is, however, petrographically similar to Cretaceous syenites described elsewhere in the Cordillera.

SODALITE SYENITE The white-weathering sodalite and related feldspathoid-poor syenites generally comprise 80 to 90% feldspars. Due to metamorphism, much of the feldspar is now Plate 4. Bouldercontaining syenite dike (white) crosscutting altered to albitic plagioclase and original potasic l'eld- banded volcaniclastic rocks. Banding parallel to pen, Bearpaw spar/plagioclase ratios are difficult to establish. Other meta- Ridge. morphic minerals include epidote (npto 10%). :nnscovite

Plate 5. Whiteweathering syenite with disseminatedsodalite, Plate 6. Folded and foliated dioritic orthogneiss, present on the Bearpaw Ridge. lower slopes of Bearpaw Ridge.

Bullefin 88 I5 British Columbia -

(generally only a fewpercent) and traces of chlorite. In one minor basaltic flows. Flow-rocks contain clinopyrcxene sample, alteration patches, consisting of fine-grained mus- phenocrysts and altered phenocrysts (now chlorite) in a covite and epidote, comprise 30% of the rock. clay aha- groundmass of opaque oxides, plagioclase and cliropy- tion was also noted locally. roxene microphenocrysts and chlorite. Some vesicles are Feldspathoid-bearing syenites occur near the centre of present. the large syenite stock. They may contain up to 10% feldspathoid minerals, generally sodalite and cancrinite or can- ORTHOGNEISS crinite alone (Plate 5). No nepheline was noted. Aegirine (strongly pleochroic from marsh to blue-green)and biotite Folded and foliated dioritic orthogneiss (Plate 6)crops are also locally present in minor amounts. Trace minerals, out on the lower slopes of the western end of Bearpaw identified by scanning electron microscopy, include mag- Ridge. It varies from a banded gneiss containing approxi- netite (titanium free), allanite, zircon, monazite, apatite, py- mately 70% calcic plagioclase (bytownite) with5% olivine, rochlore,thorite (ThSi04) and cheralite 15%augite,5tolO%magnetite-ilmeniteandatraceol'apa- [(Ca,Ce,Tht(P,Si)041.tite. maficto a -eneiss with 10%calcic Dlaeioclase..- 3046 olivine, 35% augite, 15 to 20%magnetite-ilmenite and 2 to 3% apatite. In both the feldspar-rich and feldspar-poor phases, NONDAFORMATION VOLCANICLASTIC .. ROCKS brown amphiboleis present rimming pyroxenes andlocally The Nonda Formation rocks in this vicinity largely as an intercnmnlate phase comprising 5 to 7% of the more comprise clinopyroxene crystal tuffs, calcareous tuffs and mafic gneiss. In some localities, the gneiss is remar1:ably TABLE 2 CHEMICAL ANALYSES, BEARPAWRIDGE

~. ~ Nonda Formation Other rocks /mBSi02 123 42.40 47.70 58.30 45.50 68.80 Ti02 0.12 0.11 0.09 0.13 0.47 0.10 2.06 0.59 0.80 2.01 0.27 A1203 22.80 19.40 21.65 22.10 21.80 21.10 15.20 15.80 17.90 15.60 15.70 Fe203T 2.50 2.68 3.95 2.50 4.38 2.00 14.50 6.88 7.12 11.20 1.50

MOO 0.10 0.10 0.16 0.09 0.11 0.10 0.29 0.08 0.11 0.18 0.01 ME0 0.13 0.12 0.33 0.13 0.33 0.15 9.80 4.58 0.33 5.25 0.16 CaO 0.81 0.85 5.74 0.78 3.13 4.92 11.50 17.50 0.36 12.90 0.97 Na20 11.10 6.59 6.02 11.30 6.64 4.91 1.56 0.65 7.68 3.75 4.54 K20 6.39 4.60 5.52 6.47 6.87 5.77 1.84 4.33 6.42 1.46 6.28

2.32 2.55 1.69 2.37 1.23 2.26 1.45 1.96 1.12 2.34 0.892.34 1.12 1.96 1.45 ~ 2.26 1.23 2.37 1.69 2.55 2.32 1 4.09 <0.08 <0.09<0.09<0.09 <0.09 0.23

i PPm INi < 34 <37 7 -2c 2824 219 1 Cr 62 67 50 - 30 44 51 Co 41.4 1.9 -51.617 56 Sr 50 1751 205 - 1023 55 290 3421 288 Ba 50722 170 - 1079 486 545 445 zr I 613 1831756 - 717 134429 103 133 110232 - 147 - 167 11 44 45 Y - 58 - 35 21 2520 14 10 24 LaNb 1 9: 155108 - 122 78 i 11 34 61 26 Ce 135 222156 ~ 174 111:71 38 Nd 28 32 - 22' Yb 2.7 2.9 - 1.9' sc 0.33.8 0.2 - 2.7 0.323 33 21 1.4 8.5 10 17 - 8 7.5 <2 Ta ~ 36.3 38.3 56 Th ~ 29.4- 39 l;

16 Geological Survey B~nch Ministv of Energy, Mines and Petmleurn Resources "

Y Bear aw Ridgesyenile @ ON on8 a Formotion volcclnics 0 Portorogenic syenite

0 Beorpow Ridge syenite t Nonda Formalion YOIC~II~EE 0 Porlorgogenlc syeniie \ \

30.00 40.00 50.00 60.00 70.01 Si02

I / Agpaiticsyenite fomily

nephelin ** '/syenite

Alkali bosall fomily __ 0 Postorogenic syenite CO 0.00 ,,, , , , , , , , , , , , , , , , , , ,, , , , ~, , , , , , w, 020 __ 30.00 50.00 40.00 601ao 70.0 Si07 Figure 12. Major element ternary plots, Bearpaw Ridge

Figure 11. (A) Alkali vs. silica diagram Bearpaw Ridge; beckite). Accessory minerals, identified by scann:ng elec- (B) Agpaitic index plot- Bearpaw Ridge syenites. tron microscopy, include ilmenite, pyrite, barite, monazite, sphalerite and arsenopyrite. well preserved; inothers it isstrongly altered, consisting of chlorite, epidote, plagioclase, sericite and prehnite. GEOCHEMISTRY The on the crest of POSTOROGENIC SYENITE preorogenic feldspathoidal syenites Bearpaw Ridge are variable in major element conteilt (Table A secondtype of syenite outcrops on the southwest end 21, and alkali-silica and agpaitic index plots (Figure 11) in- of Bearpaw Ridge. It is massive, coarse grained andpink dicate they span the range from saturated syenites, through weathering with randomly oriented feldspar laths up to 1.5 miaskitic syenites to agpaitic syenites, with anavert ge com- centimetres long. It comprises 30 to 35% potassic feldspar, positional range in the miaskitic syenite field. Composi- 20 to 25% plagioclase and 10 to 20% microperthite with up tional differences with the postorogenicsyenite whichcrops to 10% clinopyroxene (aegirine-augite to aegirine), 5% out on the lower slopes of Bearpaw Ridge are s1.ght; the hornblende, 5 to 7% magnetite (withtitanium)plus ilmenite feldspathoidal syenites are higherin Al2O3, CaO, 2,Nb, Ta and minor biotite and apatite. The clinopyroxenes are and Th and, on average, lower in SiOz, Fez03, 'IiOz and strongly pleochroic, from yellowish to blue-green and often PzOs than the postorogenic syenite (Table 2; Figures 11 and rimmed by strongly pleochroic blue sodic amphibole (rie- 12). Other major elements show nosystematic variation. On

Bulletin 88 17 alkali-silica andagpaiticindexplots (Figure 11) thepostoro- metres, most of which lies within Kootenay and Yoho Na- genic syenite falls within the agpaitic syenite field, however tional Parks (Figure 13). Access is difficult due to iiteep it wouldbe erroneousto classify this rocktype as suchbased mountainous topography, lack of roads andregulations im- on asingle analysis. posed by Parks Canada. The Nonda Formation volcanic and volcaniclastic The Ice River complexwas the first alkaline intnlsion rocks havealkaliisilica ratios which allow them to be clas- to be recognizedin British Columbia. It was discovered and sified as alkali basalts (Figure 11). Chemical trends suggest described around the tnm of the century (Dawson, 1885; that they may he genetically related to the syenites on the Barlow, 1902; Bonney, 1902). Work by Allan (1911,1914) ridge crest (Figure 12). established it as one of the world's major alkaline complexes. During the 1950s and 1960sthere was renewed in- GEOCHRONOLOGY terest and anumber ofadditional studies undertaken (Jones, Taylor and Stott (1979) suggested that the sodalite 1955; Gussow and Hunt, 1959; Campbell, 1961; Rapson, syenite is a subvolcanicintrusion, related to the formation 1963, 1964, Deanset al., 1966). The most recent conipre- of the Nonda volcaniclastics. If so, it would be approxi- hensive study is by Cunie (1975); much of the following mately Silurian in age. The chemistry of these rocks sug- description is summarized from Currie's Memoir anti the gests that this may be a viable interpretation; however, this reader is referred there for additional details. An excdlent alone is not snfticient to establish this relationship and there- bachelor's thesis (Peterson, 1983) deals withtheminernlogy fore the age ofthe intrusion. No radiometric dates are avail- and petrology ofthe complex andis also drawn upon ewten- able and, until the intrusion has been dated, its age is sively. In view ofthe many previous studies of the Ice Itiver uncertain. complex, only briefa description will be given here. 'hodistinct suites are present within the complex: an ICE RIVER COMPLEX (82N/1) early, rhythmically layered, feldspar-free intrusion of ,jam- The Ice River complexis an alkaline ultramafic intrn- pirangite, ijolite and urtite, cored by a carhonatite phi: and sion located 23 kilometres south of Field, at latitude crosscut by carbonatite dikes rich in mafic silicates an43 ox- 51"10'N, longitude 116°25W. It is an arcuate mass, some ides; and a later zoned and crosscutting syenitic sene;$,as- 18 kilometres long, with atotal exposure of 29 squarekilo- sociated withazeoliteandfeldspar-hearingcarhonatite.The alkaline rocks intruded Cambrian and Ordovician slales and carbonatesof the Chancellor, Ottertail and McKay formations (Plate 7; Figure 13). Contact metamorphism cC the enclosing sedimentary rocks resulted in the formation of hornfels and skarns. Some limited soda metasomatism also occurred. The complex and its hostrocks were deformed and subjected to low-grade regional metamorphism during the Columbian orogeny.

ULTRAMAFIC SERIES The older part of the complex comprises a semiconcor- dant, rhythmically layeredintrusion of feldspar-free lithologies ranging from jacupirangite through melaniteijolite to melanite urtite, and characterized by a repetitive seqcence of graded layers, 10 to 200 metres thick, with nephelinein- creasing in abundance towardthe top of each layer. Ja:upi- rangite is the most mafic lithology in this series. It conlains, in decreasing abundance, titanaugite, titaniferous ma,;netite, perovskite and phlogopite. Accessory mineralsinclude apatite, calcite, pyrrhotite, cancrinite and natrolite; the:.atter two mineralsare present as alteration products of nepheline. In many cases, the jacnpirangite has been fractured and intruded by later, more felsic phases (Plate 8). Ijolites are the most common componentof the layered series. They vary froma slightly more maficvariety (rnela- ijolite) to true ijolite. The mela-ijolites contain clinopyroxene, either titanaugite or hedenbergite, nepheline, phlogopite, magnetite andperovskite or sphene, in order of decreasing abundance. Accessory mineralsinclude calcite, Plate 7. Contact between syenites(light grey massive) of' the Ice apatite, cancrinite and natrolite. Some varieties contai~~sig- River complex and steeply dipping Paleozoic carbonate rocks, nificant amounts of blackmelanite garnet and biotite. True Butress Peak. The contacthere is clearly intrusive. ijolites differ in that the pyroxenemephelineratio is 1::I and

18 Geological Survey B,.anch Figure 13. Geology of the Ice River complex (from Cume,1976a). opaques are uncommon.Locally, kaersutite amphibole re- The syenites are all dominated by the presence of alkali places pyroxene. feldspar, generally with subordinate amountsof pwthite and Urtites contain greater amounts of nepheline than py- albitic plagioclase. Mafic minerals vary from minor roxene (generally aegirine) and wollastonite may be pre- amounts to comprising approximately 50% of the rock. sent. They are generally coarse grained, with a fabric Melanocratic varieties are characterized by the presence of developed due to the parallel orientation of elongate py- titanaugite to hedenbergitic pyroxeneeaersutitekbiotite. roxene or wollastonite. Kaersutite, melanite, albite, Leucocratic syenites generally contain minor amounts of nepheline alteration products, sphene, calcite and apatite aegirine; hedenbergitic pyroxene, kaersutite, hastingsite or may also be present. biotite may also be present. In all varieties, nepheline may comprise upto 30%of the rock. Sodalite is preser~tin quan- tities from trace amounts to 20%, and is generally more ZONED SYENITE COMPLEX abundant inthe leucocratic syenites. It occurs bot1 dissemi- The youngerportion of the Ice River complex hasin- nated throughoutthe syenite and concentratedin veins cut- truded the older mafic portion and consists of feldspar-rich ling the syenites. Accessory minerals include s:?hene (no syenitic rocks. The syenites are unlayered, however, there perovskite), apatite, cancrinite and minoropaquen. Zeolite- is a strong alignment and segregation of minerals. They rich syenites are present locally; fluorite and pyrochlore form an elliptical pipe-like mass, zoned from a greenish so- have also been reported (Peterson, 1983). dalite syenite core through pale grey nepheline syenite to darker coloured mafic-rich rocks at the margin. The com- CARBONATITES plex is surrounded by a thin rim of saturated fine-grained Carbonatites crop out in a number of localities in the leucosyenite in contact with the country rocks. This phase Ice River complex anddisplay considerable lithologic .vari- is commonly full of inclusions. ation. Complex relationships with other alkaline rocks pre- Plate9. White-weathering,coarse-grainedcarbonatitedike,Alount Plate 8. Jacupirangite (dark grey massive)of the IceRiver complex Sharp area, Ice River complex. Coarse-grained dark minerals are and steely dipping carbonate rocks, Butress Peak.The contact here books of biotite. Sugary appearance of white matrix produced by is clearlyintrusive. coarse apatitegrains mixed in with the calcite. clude the unambiguous establishment of an emplacement generally coarse grained and composedof calcite, aeglrine, sequence. Currie(1975) suggests there may be some remo- apatite, pyrite and trace pyrochlore. bilization of carbonatite during deformation andmetamor- White-weathering carbonatite dikes (Plate 9) inlrude phism whichresults in complex crosscutting relationships; the ultramafics exposed on Sharp Mountain (Figure 13). alternatively there may be morethan one period of carbona- They consist predominantly of calcite and fluorapatite with tite emplacement. aegirine (occasionally containing hedenbergitic cores), Carbonatite occursin the layered ultramafic sequence, phlogopite, pyrite and ilmenite/magnetite. Some samples westoftheIceRiver(Figure13)aslayeredlenticularmasses contain feldspar-rich xenoliths (microcline plus a1hite:l and and as smaller dikes. Three types are recognized: ablack- garnet (melanite?), analcime, natrolite, cancrinite and weathering, iron-rich variety which is associated with a sphene. buff-weatheringcalcite-rich type, and ared-weathering va- The carbonatite associated with the syenites is radit:ally riety, which crosscuts the buff carbonatite. The black car- different fromthat occurring within the ultramafic series in bonatites commonly occur as dikes containing elemental that the only silicate minerals present are feldspars (albite carbon and tetranatrolite concentrated near the margins, and in some localities microcline), zeolites (natrolite, mal- with calcite, siderite and grass-green berthierine cime and rarely, edingtonite) and rare phlogopite. In some [(Fe2t,Fe3',Mg)z-3(Si,Al)zO~(0H)~,a serpentine mineral] localities the carbonate is pure calcite, in others ankcrite, as major components. Other mineralsin the black carbona- barytocalcite and strontianite have been identified in addi- tite are: iron-rich biotite, aegirine, edingtonite (a barium tion to calcite. Minor and trace minerals include ilmenite, zeolite), perovskite, ilmenite, minor sphalerite and traces of pyrite, rutile, barite and apatite. pyrite. The red-weathering carbonatite is similar to the black, but it contains fewer non-carbonate minerals (less LAMPROPHYRES than 10%);both siderite and zeolites are absent, serpentine Many dark-weathering lamprophyric dikes o;cur is distinctly yellow-brown rather than grass-green, and py- within the Ice River complex and contiguous countryrocks. rochlore and xenotime are present. The buff carbonatite is They contain phenocrysts of strongly pleochroic orange-

20 Geological Survey Branch ~ ~~~~ ""

Ministry of Energy, Mines and Petrnleum Resources

TABLE 3 CHEMICAL COMPOSITIONS OF ICE RIVER COMPLEX ROCKS

M ch-ijolie Melanie ljolote JacutpimgjeMelanie Mch-ijolie 'j0'- Uni* carbonatill

si02 34.2 37.9 33.6 41.6 42 40 35.9 39 40.2 43.7 43.9 40.3 43.5 44.2 1.2 7.7 1.6 9.92 12.38 9.65 20.24 12.93 16.24 Ti02 5.62 5.64 7.14 2.21 3.22 2.42 4.4 2.04 3.48 1.2 2.44 3.58 0.19 0.14 0.02 0.09 0.05 0.07 0.38 0.07 0.73 0.77 2.21 5.6 8,7 9.9 11.6 12.4 12.5 19.1 20.2 19.8 25.8 19.3 21.3 26.2 26.1 0.3 2.6 0.4 2.84 1.62 2.76 4.65 6.14 4.$1 8.9 2.1 6.4 2.9 4.1 2.8 4.8 3.3 2.5 1.6 2.4 2.4 1.1 1.3 0.1 2 0.2 1.62 5.9 0.53 5.37 8.7 5.89 8.2 7.4 7.4 6.9 4.3 8.2 5.7 3.7 5.4 4.9 5.4 3.7 5.7 8.2 4.38.5 6.9 7.46.2 7.4 8.2 21 0.73.2 0.8 8.9 - - 0.18 0.2 0.2 0.18 0.17 0.28 0.2 0.15 0.2 0.12 0.5 0.51 1.75 0.31 0.4 0.13 0.140.13 0.4 0.31 1.75 0.51 0.5 0.12 0.120.2 0.15 0.2 0.28 0.17 0.060.18 0.2 0.2 0.18 0.07 1.15 1.1 0.98 10.6 8.4 9.8 11.6 11.6 10.4 4.1 4.7 5.6 0.27 5.1 2.7 0.4 0.7 12.7 0.7 0.4 2.7 5.10.27 5.6 4.7 4.110.4 11.6 11.6 9.8 8.410.6 0.5 0.440.2 1.254.27 8.85 0.4 2.01 21.8 27.2 21.4 11.7 12.3 12.3 11.7 9.5 10.1 5.410.1 9.5 11.712.312.311.7 21.4 27.2 21.8 6.6 I145.5551.86 30.644.6239.7347.1227.58 19.136.4 :27.8 9.7 3.3 3.5 4 8.7 7.7 7.4 9.9 7.4 7.6 10.4 10.6 0.1310.6 10.4 Na2O 7.6 1.08 7.40.8 9.9 0.7 7.4 7.7 8.7 4 3.5 3.3 1.120.31.44 1.79 0.2 nd 1.912.25 Kzo 0.120.3 4.6 2.6 0.4 3.31.45 0.12.74 0.32 0.36 0.03 0.05 1.9 0.11 4.6 4.9 3.9 5.43.6 4.5 3.5 3.7 H200.8 0.7 0.8 15 0.9 0.72.1 0.7 0.6 0.9 1.2 0.7 0.9 0.9 1.3 0.5 0.5 .A nil 0.02 0.M1.9 0.1 0.3 0.2 0.5 0.20.8 0.1 43.4436.943.629.3723.430.7 35.03 23.760.3 :!5.27 21.87 2.54 l.W 1.94 1.240.511.120.560.620.33 0.09 0.110.050.670.36 0.01 0.05 0.1 2.068.237.81 0 0.20.92 99.799.0 100.6 98.01W.9 IW.7 99.5 IW.O 109 IW.499.9 99.4 lW.2 99.51 99.9100.8 99.6 98.64 95.62 99.13 94.9 1 1 -1 !nU9%.l5 I __- 110 nd 190 40 61 49 nd nd 11 nd 13 3 10 4.0 65 l2S 6626 21 nd nd nd 2810 3443 8 303 3W303 140 3600 2wO 25W 1376313628 12768 3954 11610 7907 3W 16 3W 1300 320 m 1IW 890 360 213%22139221511528 190 470 210 220 2M)/ nd 340 nd 35248 587 415 60 62 370 150 230 170 250 444 224 1x7 71 71 40 22 68 1701 :: 81 10a0 620 145 43143 159 125 81 450 86 50 98 60 650 7W 2M) 439930 535 €41 418 nd 650 nd nd nd nd 1oW 880 4W 15627M878 8521530 nd IlW 830 nd nd nd 820 1wO nd ". 4 5.1 4 4.7 4 c4 c4 c40 <40 <4 <4 <4 ... 52 26 39 nd nd ." Od; - 41. 36 39 2626 .. ." ; 1 "" QQQ14 6 13 I.. ." ." ".. 79 <6 81 ____703511 Lampmphyrs Melanacmtic syeoite lrucOcraG0 syenie sodalite syenite (1) (2) (3) si02 46.762.1 51.9 44.444.741.6 45.3 58.653.954.652 54.4 54.t Ti02 1.141.930.28 0.19 0.41 0.63 4.3 0 2.77 1.010.7 0.110.81 1.68 0.12 0.2 0.C 'A1203 20.1 23.321.821.624.1 18.322.4 23.119.120.418.4 23.8 20.716.416.315.6 13.4 22.1 21.9 20.8 Fern3 2.1 2.6 1.21 2.1 1.2 0.81.3 0.6 2 3.1 0.4 7.1 4.6 7.1 4.3 5.1 4.1 0.1 5.8 1.4 4.8 3 7.8 0.8 2.15.5 7.1 5.9 0.30.9 0.4 (MnOFd) 0.120.150.180.190.130.420.320.050.160.070.110.160.220.2 0.C 11.6 6.1 4.2 4.$ 0.2 2.8 1 5.1 1.4 0.6 1 0.5 0.1 0.5 1 0.6 1.4 5.1 1 2.8 0.2 4.$ 4.2 MgO 6.1 11.6 0.4 0.1 0.8 0.1 cao16.7 14.4 16.3 13.8 0.73.4 1.6 1.9 7.8 12.1 6.5 11.8 3.6 6.1 0.30.2 0.5 4.1 1.2 0.7 '4 2.8 5.1 5.8 5.1 2.8 7.8 5.9 5.79 4.7 7.1 7.6 9.9 7.99 7.8 6.8 5.7 8.3 11.510.710.1 Kzo 2.12.3 2.3 2.3 5 0.4 6.3 5.4 3.2 6.9 8.6 7.8 4.1 2.16.3 4.4 3.6 7.56.3 5.3 1.6 1.4 1.6 1.2 1.91.6 0.9 1.3 0.9 Oh 0.7 OS 0.9 5.4 0.9 0.9 1 0.7 0.8 0.8 0.7 0.9 1.3 1.2 1.4 1.2 1.3 0.9 0 0.2 0 0.1 0.03 0.90 0.2 0 0.2 0.05 0.1 0.1 0.7 0.2 0.8 0.74 0.96 0.91 0.47 0.05 0.28 0.02 0.03 0.470.030.020.28 0.05 0.47 0.91 0.96 0.74 0.W 0.220.310.190.77 0.09 0 0.08 0.02 0.01 0.1 99.81W.2 1W.6 99.7 99.7 IW.5 1W.8 1W.S 10.0 1W.3100.1 IW.5 100.5 99.4 100.0 98.2 98.4 99.399.8 101.1

__ "I Ni 150 220 40 24 40 36 nd nd 40 nd 21 nd nd nd - 5wJ MD 16 16 40 17 40 nd nd nd nd 40 40 nd - 45 nd nd 40 nd 31 nd nd nd nd nd nd nd nd - %o 920 2%W 170012W 990 25W ZoW118%1800770 2600 380 ZM) - 490 280 2wO 1wO 17W1wO37W 26(M 34w 14M 350 2SW 130280 . 350 I80 120 410330 160 690 190,450 270 390 300 310 280 370 - 1mO 110 nd 203 510180270 310 14w 240, 140580 140 140 2W - 980 22 33 nd 4235 51 47 94 28 40 61 nd nd nd - 300 59 40 73 55 170 150 93 9499 110 1500 nd nd 210 - 180 Ce nd 22 nd nd nd nd nd 17W ndnd nd nd nd 290 - nd Nd nd od nd nd nd nd nd 740 nd nd nd nd nd 160 - yb <40 <40 <4 c4 <4 c4<4 <4 c45.7 4 4 - - - SC 34 27 dl20 od 17 nd 14 nd nd nd nd- - - Ta .. ..".._._._. lll ...... i ~

Bullerin 88 21 brown phlogopite, zoned crystals of angitekitanangite, grams (Figure 14). They form a cogenetic suite and eAibit zoned kaersutite and olivine in a groundmass of pyroxene, systematic major element variation with Si02, Na2Cl and pale orange phlogopite, calcite, alkali feldspar and opaque &O increasing and CaO, TiOz, Fez03 and FeO decreasing oxides. Sphene and apatite have also been reported. Field with decreasing colour index(that is, from jacupirangite to relationships indicate that the dikes were emplacedlate in urtite, Table3; Figure 15). Rocks of the ultramafic sui:e are history of the complex. generally lower in Si02 and higher in CaO and Ti02 than those of the syenitic series (Table 3). GEOCHEMISTRY Syenites of the Ice River complex range fromnephelin- Rocks of the layeredultramafic complex belongto the itic (melanocratic varieties) to agpaitic (leucocratic and nephelinite family and plot predominantly within the feldspathoidal varieties) in composition (Figure 16). They nephelinite fields on alkali-silica and agpaitic index dia- exhibit systematic major elementvariation with decreasing CaO, MgO and total iron, and increasing alkalis with decreasing colour index (from melanocraticto leucocratic and feldspathoidal varieties, Figure 17).

/ \ A ljolite and @ melaniteijuiite 0 Wile 0 Melo-ijolife * Josupirongiie Mela-ijolite Corbomtite,/ A ljolite and family Agpoiiic syenite family "51 melanite ijolitt b Urtite Miaskitic /\

Alkoli basalt rocks family I***/ 0.00"" 0.00"" 30.00 40.00 50.00 60.00 ?;I%

Figure14. Alkali-silica and agpaiticindex plots, Ice River ultramafic suite. Figure 15. Ternarymajor elementplots, IceRiverultramafk suite.

22 Geological Survey €:ranch Sodalitesyenite LBUCOCratiC ryeniter A Meianocraticryenil Melonocratic syenite 0 Contactsyenite an, ZeoliteContactbreccia ryeniter syenite & breccia b Leucocratic syenila 1\

Sodalife syenife Nepheline syenite LeucOCrOtiC syenites Melonosrafic syenif 30.00 40.0060.00 50.00 - Contact ryenite & Si02 breccia

TtMelanocratic :yenit DContact syenbte an /D breccia 0 \ 0 Leucocratic syenile 4 0 Sodalitesyenite *Zeolite svenite

a \ r + CI 0 z Figure 17. Ternary major element plots, Ice River syenitic suite.

.-"- .-

Subalkaline rocks Alkali basalt family

0.00 30.00 40.00 60.00 50.00 si09

Figure 16. Alkali-silica and agpaitic indexpbts, Ice River syenite suite.

Carbonatites &e predominantly sovites and ferrocarbonatites (Figure 18) and, togetherwith someof the melanocratic syenites, have relatively high concentrations of * Corbonolites near Mom1 Mollison and EultressPeak \ 'incompatible' trace elements (Nb, Y, REE), barium and * Corbonolites associated strontium (Table 3). with theultramafic complex, Sharp Mt. Xundifferentiated Other, GEOCHRONOLOGY I \ The ageof emplacement of the Ice River complex has long been a topic ofdebate. Allan (1914) suggested that em- Figure 18. Majorelement ternary plot, Ice River 'Zoom[ placement was post-Cretaceous, Gussow and Hunt (1959) carbonatites.I

Bulletin 88 23 TABLE 4

ICE RIVER COMPLEX SUMMARY ~ ~~ ~ ~~ ~~ -~GiOCHRONOLOGY ~~ - ~ I Published Date Recalculated* Method Reference Comments Reference Method Recalculated* Date - 392t10 374t10 Rapson,rockwholeK-Ar,1963 Pyroxenite; age possibly slightlytm old, excess argon possible in pyroxene (2s~f3o) Rb-Sr,mica separate Rapson, 1963 Biotite pegmatite: Sr tm low for satisfactorydata but K-Ar should be reliable 336*5 3216 K-Ar,mica separate Rapson, 1763 Minene sill; Sr too low for satisfactory data but (244*45) Rb-Sr, mica separate K-Ar should be reliable 327*5 312G separatemica K-AI, 34Ot23 348~27 IC-Ar, mica sepmte Lowdon,1960Syenite d%e, no chlorite 330+23 334t26 separateK-Ar,mica Lowdon, Fyroxenite; 1960 chlorite no 355+18 362t18 K-Ar,mica separate Baadsgaard, 1961 Jacupirangite 3&18 367t18 micaseparateK-AI, Baadsgaard, 1961 Minette 304+15 31045 separateBaadsgaard,micaK-AI, Pegmatite 1761 (233+11)(231+10) K-AI, mica Separate Cumie, 1975; Wanless, 1973 Me@-ijolite: noalteration (discordant, low) (22Df8) (227t10) K-Ar,mica separate Cume, 1775: Wanless, 1973 Nepheline syenite; noalteration (discordant, low) (408k15)(415*15) K-Ar, mica separateWanless, 1966 Altered lamptnphyre (421+11) K-Ar,hornblende Stevens, Hornblende1982 from syenite: excess argon separate 368-370U-Pb, Ma zircon spheneParrish,1987 207PbDMPb ageson zircon as follows:359.9i2.2: 363.1*2.2: 364.9t2.2; sphene368.8t7.D: 357.3*8.4;361.2t9.0;356.6~16.1. 'Dola me reealnrloted using currenflyoccepled decay con~lenls,R.L Amlrong, persoml communicolion, 198% examined contact relationships and concluded that the com- 1979, mapping, soil and rock geochemistty and trenching plex wasa sample of Precambrian basement and thecontact were doneto assess the fluorspar-lead-zinc potential of the with the sediments wasan unconformity.Radiometric dates property (Bending,1978; Alonis, 1979). More recent work obtained in the early 1960s (Lowdon,1960; Baadsgaard et (Graf, 1981,1985) attemptedto establish the economic po- al., 1961; Rapson, 1963) suggested a mid-Paleozoic age, tential of the property interms of other commodities.Duing circa Devono-Mississippian (Table 4). Cunie (197.51, uncertain of the validity of the early radiometric work, had this latter work it was discovered that the property also :on- additional material analysed and obtained Early Triassic tained anomalous concentrations of rare-earth elements ages (see Table 4). In evaluating his, and earlier work, Cume WE). suggested apreferred age of emplacement of circa 245 Ma. The Rock Canyon Creek area is underlain by a Cam- Recent work on uranium-leadzircon systematics (Panish et bro-Ordovician to Middle Devonian carbonate-dominated al., 1987; also see Table 4) indicates that the mid-Paleozoic sequence (Leech, 1979; Mottetal., 1986). Theregionahtra- dates most closely represent the true age of emplacement. tigraphy has been previously describedby Mott et al. and only relevant points will be reiterated here. The southu,est- ROCK CANYON CREEK FLUORITE AND em boundary of the property is marked by the eastemmost RARE-EARTH ELEMENT SHOWING in a series of west-dipping thrust faults which place Cam- (825/3E) brian and Ordovician strata over younger rocks (Figure 19). The Rock Canyon Creek showing (Candy and Deep The remainderof tbe area is underlain by an overturned to Purple claims) occurs nearthe headwaters of Rock Canyon upright homoclinal sequence, yonnging to the east. This Creek (Figure 19) in theeastern White Riverdrainage, ap- succession comprisescoral-rich limestones of the Ordovi- proximately 40 kilometres east of Canal Flats (latitude cianBeaverfootFormationinthenorthwest,unconformably 50'12'N. longitude 115"OSW). It is accessible by conven- overlain by buff-weathering dolomites andsolution brec4:ias tional vehicles along the White River and Canyon Creek of the basal Devonian unit which are, in turn, conformably forestryroads, whichjoinHighway3Atwokilometressouth overlain by fossiliferous and nodulargrey limestones of the of Canal Flats.The main mineralized zonelies between the Fairholm Group. The fluorspar and REE mineralization is 1525 and 2000-metre elevations in a valley that has been stratabound, hosted mainly by the basal Devonian unit. burnt-overand subsequentlylogged. Access is excellent, but exposure poor due to thick drift cover. Acarbonatite-related origin has been suggestedfor the The prospect was discoveredin 1977 duringa regional showing (Graf, 1985; Hora andKwong, 1986; Pell, 19117), exploration program camed out by Riocanex (then Rio which consists of metasomatically altered (fenitized) :De- Tinto Canadian ExplorationLtd.), in search of Mississippi vonian carbonate rocks, possibly associated with a deep- Valley-type lead-zinc mineralization. Between 197'7 and seated carhnatite intrusion.

24 Geological Survey Branch Ministry of Energy, Mines and Petroleum Resources

[(Ba,Ca,Ce)A13(P04)z(OH)3 HzO], calcite, limorite, illite and barite are common accessory minerals (IIora and Kwong, 1986). Parisite [CaCez(C03)3Fz] has also been identified from fy of the Rock luorite veins by scanning electron microscopy and may be associated aith bastnaesite. Neutronactivation analyses of up to 2.3% lare-earth elements and 2.7% barium have beenreported (Gl,af, 1985; also Appendix 1). Niobium,strontium and yttriumare also present in measurable amounts(Table 5). Contacts between mineralized and unmineralized dolomitic rocks aregrada- tional; the amount of fluorite veining decreases and col-the our of the rocks changesgradually from dark brownto grey or buff, the characteristic colonr of unaltered dolomites in the area. This type of mineralization defines a northwest- trending zone mappablefor over akilometre, subparal1c:l to strike (Figure 19). The second typeof mineralization consists ol'massive, fine-grained purple and white fluorite, which csmmonly comprises greater than 40% of the rock, together with accessory prosopite [CaAlz(F,OH)3], gorceixite, pyrite and minor barite, calcite, rutile and kaolinite (Hora adKwong, 1986). Chemical analyses indicate that this type of mineralization can contain up to 71% CaFz. The rare-earth element and pyrite contents of these rocks arerelatively low. Massive fluorite mineralization has notbeen found in place, hut abundantfloat occurs at the southeast end of the zone of Type 1 mineralization, near the nortb-flowing Ixanch of Rock Canyon Creek(Figure 19). Fine-grained purple fluorite disseminated in white calcite whichis locally interbeddedwithbuff-weatheringdolo- LEGEND mite and forms the matrix of solution breccias constitutes UPPERDEVONIAN the third type of mineralization. Fluorspar is prese nt in con- mFairholm Group-greylimestone centrations from trace amounts to a few percent. Minor sare- nodularlimestone, dolomite and earth element enrichmentis also reported (Graf,11385). 'This argillaceouslimestone type of mineralization is found randomly distributed MIDDLEAND/OR UPPER DEVONIAN throughout the basal Devonian unit. mBasal DevonianUnit-dolomite, fourth type of fluorspar mineralization occurs in mudstone and solutionbreccia The rocks tentatively assigned to the Devonian FairhalmGroup UPPERORDOVICIAN AND LOWER SILURIAN MBeoverfoot Formation-limestone, and is found in one locality,at the2135-metre elwationon dolomite and abundantcorals the ridge east of the headwaters of Rock Canyon Creek (Fig- LOWERAND MIDDLE ORDOVICIAN ure 19). Massive purple fluorite which constitutes greater Losk/Skoki Formation-dolomite,limestone than 20% of the rock, forms the matrix of an irttrafonna- andsandstone tional conglomerate(Plate 10) and locally replaces the irag- mGlenogle Formation-shale ments. Minor barite, pyrite and magnetite may also be present. CAMBRIANAND ORDOVICIAN MMcKoy Group-limestoneand shale GEOCHEMISTRY Figure 19. Geology of the Rock Canyon Creek fluorite rare-earth The interpretation that the Rock Canyon Creek show- showing. Modified from Pel1 and Hora (1987) and Mott (1986). ing is carbonatite related appears to be consistenl with pre- MINERALIZATION liminary geochemical data (Table 5; Appendix 1). In addition to high fluorine, REE and barium, the rock:! are Four main types of fluorite mineralization are identifi- enriched in Fez03, MnO, MgO, strontium, yttrium, phos- able in the field. The first and most widespreadconsists of phorus and niobium (Table 5) relative to the unaltered De- disseminations and fineveinlets of dark purplefluorite in a vonian carbonates. Chondrite-normalized rare-earth dark brown to dark orange-brown weathering dolomitic ma- element abundancepatterns are typical of carboniltites (Fig- trix. Fluorite content generally varies from 2to greater than ure 20) and fall within the field defined by off ler Blitish 10% of the rock. Bastnaesite (CeC03F) often occurs along Columbia carbonatites, however, the Rock Can:,on Creek the margins of fluorite veins, as does coarsely crystalline showing is more enrichedin rare earths than most other ex- dolomite. Disseminated pyrite, gorceixite amples, comparable only withthe REE 'sweats' and dikes

Bulletin 88 25 TABLE 5 CHEMICALANALYSES, ROCKCANYON CREEK

Weakly altered carbonates, adjacent to Type1 .. Type 1 mineralization Type 2 mineralization mineralization 2 3 4 3 1 2 5 6 7 16 "___.~ 1513 14 0.39 3.16 0.85 2.89 0.94 2.82 1.04 6.397.84 9.34 22.79 0.02 0.02 0.01 0.03 0.03 0.030.06 0.020.41 0.04 0.10 A1203li 2.32 1.07 0.20 1.10 0.37 0.431.24 17.1615.3117.05 2.25 Fe203 2.80 2.80 2.95 3.26 5.28 3.6415.49 7.41 1.10 0.392.04 1.061 1.810.53 0.64 1.29 0.78 1.01 1.09 1.49 1.62 0.961 0.01 0.16 <.010.16 0.01 0.090.961 1.62 1.49 1.111.09 1.01 0.78 0.110.021<.011 <.01 <.01 10.30 14.40 12.86 12.61 13.40 11.80 14.26 14.00 8.96 10.53 2.40 4.23 0.17 0.22 11.790.22 0.17 4.23 2.40 10.53 8.96 14.0014.26 11.80 13.40 12.61 12.86 14.40 10.30 34.7029.4037.4537.57 32.89 26.36 29.00 30.811 32.1019.05 46.60 40.491 42.0839.59 4ZI 2;:fi;I 0.08 0.05 nd nd 0.220.23 0.16 nd <0.03 0.550.080.24 0.18 0.01 0.06 0.23 0.25 nd nd 0.01 0.02 0.060.931 0.58 3.27 2.47 0.05 0.13 29.9735.4933.3035.3635.6134.2839.7832.8025.6840.8034.0412.8812.02 1.49 0.59 0.36 0.31 0.34 1.52 0.92 <.09 0.26 0.12 0.14, 0.17 1.670.17 0.14, 0.12 0.26 <.09 0.92 1.52 0.34 0.31 0.36 0.59 1.49 0.14, 2iil 83.2988.34 88.76 93.14 90.12~ 87.23 ~92.85 93.02 82.4979.24 77.89 95.29 98.01 94.99 99.87

9 8 9 4 3-3 6 2411 2 7 3 Q 22 28 12 28 22 40 39 - 1726 27 QO 34 10 12 6 7 7 7 9 7 7 7 10 6 10 6 118 2 4 1129 >loo00 7759136934289817351260133460816761024 3723 13581483 300 982024226 11538 4078 1306 14953 95010942 790 465352 54 138401221513582 136 49 4137 49 42 28 52 21 3475 45 23 41 54 158 149 303149 158 54 181 40 162 20 5 53 63 48 278 157 147 174 165 317 146 224146 317 165 174 147 157 278 15 90 <5 157 17 163 15 21 24 45 56542833487645 2318 531924 6072 3803 2683 5 18 530 125 111 44 859643656285395778588986 6302 5009 48 42 95 19 142 948 178 45 4 : -I - - -I i :I <3-I 81 69 92 81 107 81 92 69 81 47 - 43 7038 32 47 <2 7<2<2<3 -<2<2aaa 5 1120 188 305 201 412 407 263 428263 407 412 201 305 188 1120 36 47 52 43 460 134 45 2.00% 4.80%6.52% 4.50% 6.40% 2.96% 3.13% 1.75% 2.90%1.43% 0.90% 0.51% 33.28%32.00% 34.56% - 6.08% Sample descriptions: 1- massivefluorite in altered carbonate: 10 - grey to bug laminated carbonate with minorfluorite; A' 2 - brown, alteredcarbonate with streakroffluorite; 11 - light grey laminafed carbonate with grey altemtion patches; 3 - brown, altered carbonatewith abundantfluorite; 12 - grey to bufj laminated carbonate with traces offluorite; 4 - brown, alteredcarbonate withfluorite; 13 - massive purple and whitefluorite with some calcite; 5 -fluorite veins in altered carbonate; 14 - purplefluorite; 6 -fluorite in altered carbonate; 15 -massive white andpurplefluorite; 7 - chocolate-weathering alteredcarbonate rockwithfluorite; 16 - intrafomtiod limestone conglomerate withfluoritematrix; 8 - brown, altered carbonate; Samples1,2,5,6,7,9,11nnd13tol6majorelementsbylCP;trace 0 L_n"" I.~. ~.~..I v . " . , a. -,.".- Y*,, ~UIYVI'U'T WL,,' wu,uunz,ruunrr;. elements byXKForlNA.4; Samples3,4,8,10,12 majorandtrace elements byXRF CHONDRITE-NORMALIZEDREE PLOl ROCKCANYON CREEK FENITES

La Ce Pr Nd Sm Eu Tb Dy Ho Ttn Yb L Rare-earfh Elements Figure 20. Chondrite normalized REE plot - Rock CanyonCreek fenites.

Plate 10. Intraformationalconglomerate with matrix entirely KECHIKA RIVER AREA(94L/ll, 12,13) consisting of dark purple fluorite from the Devonian Fairholm A suite of alkaline igneous rocks consisting of Group along the ridge crest eastof the Rock Canyon Creek (rype 4 fluorspar mineralization). trachytes, trachytic breccias, crystal and lapi:!.li tuffs, syenites, melanocratic augite syenites, an alkaline 'diatreme associated with the Aley complex (Mader, 1987). and pos- and related dikes and numerousstrongly sheared andaltered sibly some lithologies in the Kecbika River area. rocks, crops outin the Kechika Rangesof the Cassim Moun- tains (RAR and REE claims). These rocks have been explored for their yttrium and rare-earth element potlmtial. GEOCHRONOLOGY The alkaline rocks are intermittently expored in a Timing of metasomatism is poorly defined. Minerali- northwest-trending zone in excess of 20 kilometres !ong, the zation apparently occurred prior to the Jura-Cretaceousde- centre of which is approximately 58O42' north and 127O30' formation, as no fluorite is observed west of the west (Figure 21). Elevations in the area range from 1180 to west-boundary fault, and postdated at least part of the depo- 2315 metres, and there is excellent exposure abovetreeline. sition ofthe basal Devonian unit. This broadly defines a time Access is by helicopter from Dease Lake, approximately 160 kilometres to the west or from Watson Lake, Yukon, span of 280 Ma during which mineralization musthave oc- which is approximately 150 kilometresnorth of the prop- curred. Some mineralization (Vpes 3 and 4, fluorite asso- erty. ciated with solution breccias and intraformational The area is underlain by unmetamorphosed to weakly conglomerate matrix) may have resulted from elementalre- metamorphosed Cambrian to middle Paleozoic strata mobilization, and therefore postdate the Type 1 and 2fluo- (Gabrielse, 1962). To the northeast of the area (Figure 20, rite and rare-earth deposits. It has been suggested that thick-bedded quartzites of probable Early Cambriar ageare mineralization may have been synchronous withdeposition folded in a broad open antiformwith a northwest-trending axis. Along the southwestern limb of the antiform, the of the basal Devonian unit (Graf, 1985). A slightly younger quartzites areincontact with athick, southwest-dippingsec- age is favoured as most other carbonatites in the province tion of phyllites, thin-bedded marblesand massive, bloclcy are Devono-Mississippianto early Mississippian (circa 350 weathering dolostonesof probable Middleand Uppt:r Carn- Ma) in age. brian and Ordovician age (Gabrielse, 1962). Chlorite,

Bulletin 88 27 sericite, sericite-graphite and calcareous phyllites are all (malignites), displaying good igneous textures, predomi- present within this succession. To the southwest, the phyl- nate in the south. These syenites contain some irregula: leu- lites are bounded by a gently southwest-dippingfault, which cocratic zones and are brecciated along their margins. juxtaposes greentuffs and cherty tuffs overlain by fossilif- Numerous small sills, dikes and metasomatic alteration erous grey limestones and pinkblack and quartzites with the zones are present peripheral to the main intrusive body. phyllites. The limestones, which contain beds rich in ru- A diatreme breccia pipe is exposed near the cenlre of gosan corals, favosites-type corals, bryozoans and brachi- the property (Figures 21 and 22; see Chapter 5). The pipe opod fragments are probably of middle Paleozoic age contains xenoliths of numerous sedimentary and igrmus (Silurian). The cherts, tuffs and limestonesin the fault panel rock types and rare chrome spinel xenocrysts, in a pale outline an overturned antiformand, to the southwest, are in green, carbonate-rich tuffisitic matrix.The diatreme, which fault contact with graphite-sericite and chlorite-sericite is close to the northeast bounding fault, is weakly to strongly phyllites similar to those to the northeast. The gently dip- deformed andlocally cut by carbonatite dikes and cwbon- ping, northeastern boundingfault apparently has had normal ate-sulphide veins. movement alongit, as younger strata are present inthe hang- A large area underlain by igneous rocks, including the ingwall package,however, geometry and thepresence of the main mineralizedzone, is present immediately northwmtof hangingwall anticline imply that at one time there probably diatreme (Figure 22). It consists a complex, southwest- was thrust motion along this fault. The southwesternfault is of dipping homoclinal sequence moderately to strongly de- a moderateto steeply southwest-dippingthrust which places of formed (sheared) igneous andpyroclastic rocks. older rocks over youngerrocks. The alkaline rocks arepresent in the tuff-chert-limestone thrust panel, between the The base of the sequence is composed of palegreen to two phyllitic units. pale orange weathering,variably calcareous rocks that locally contain rare chrome spinels. These rocks areinterlay- ered with a minor amount of grey aplite and buff to DISTRIBUTIONAND FIELDRELATIONSHIPS brown-weathering, fine to coarse breccias interlayered with OF ALXALINE ROCKS fine-grained, laminatedbeds. Well-developed gradedhyers Alkaline igneous rocks occurin four main areas of the are present locally.The coarsebreccias and the bases of the property (Figure 21). Dark green, intrusive mafic syenites graded beds consist of lithic fragments, 1 to 3 centimetres

Figure 21. Generalized geology Kechika area. - 28 Geological Survey Branch Ministry of Energy, Mines and Petroleum Resources

N I

Figure 22. Geology of the central part of the belt of alkaline rocks, Kechikaarea. across, in a welded tuff matrix containing abundantflattened weathering, extremely carbonate andsericite-rich varieties. pumice fragments and altered crystals. Fine-grained, car- This unit is generally weakly to moderately foliated, bonate-rich material is present at thetop of the graded beds. strongly lineated and, in thin section, displays a mylonitic This part of the section is interpreted as comprising aseries fabric. These rocksare tentatively interpreted as trxhytic or of fine-grained, locally calcareous tuffs, crystal and lapilli syenitic tuffs or flows with, possibly, a minor sedimentary welded tuffs with some interlayered sedimentary material component; the degree of deformation makesrecognition of and, locally, sills. the protolith very difficult. It is overlain by predominantly whiteto locally buff and Dark green mafic syenites that grade from medium- pinkish weathering rocks containing varying amounts of grained, igneous-textured rocksto foliated chlorite schists quartz, feldspar, apatite, carbonate and sericite. Yttrium near the margins, are present near the top of the :sequence. minerals occur withinthis white-weatheringhorizon, appar- The mafic syenites appear to have been intrusiv: into the ently related to phosphate-rich areas. Locally this rocktype white-weathering, quartz-feldspar-apatite-cmbonate- grades into grey-weathering (graphitic?) varieties or rusty sericite sequence and arenow present as a megaboudin.

Bulletin 88 29 British Columbia

These rocks are structurally overlain by an unusual lower unit. At the north end of the zone, this unit is in fault breccia unit. To the north, this breccia consists of predomi- contact with lower Paleozoicphyllites; to the south it inter- nantly subangularclastsin a very fine grained, buff to light fingers with black siltstones and is overlain by a pde to grey matrix rich in pumice fragments. To the south, it is medium green weathering, medium-grained igneous :flows rusty weathering and contains predominantly subrounded or sills ofuncertain affiliation. Rusty weatheringcarbolatite fragments in a carbonate-rich matrix. Inboth areas the brec- dikes and green to orange-weathering fragmentaldikes or cia is multilithic, containing a variety of sedimentary and sills occur in numerous locations throughout the sequmce. igneous rock fragments; notably absentwithin the fragment At the north end of the property athick section of alka- suite are mafic syenites. Fluorite and pyrite are common line igneous rocks is exposed. It consists mainly of a com- accessoryminerals in the breccias, both disseminatedwithin plex sequence of pale green to orange to buff-weatbering the matrix and replacing fragments. Locally, a unique, buff- agglomerate breccias and tuffs, buffand greyaplite layers, weathering feldspar-porphyrytic trachyte structurally un- white-weathering quartz-feldspar-carbonate-sericiterocks derlies the breccias and contributes clasts to the breccias. and some sedimentary interlayers. Only reconnaissance The trachytes are interpreted as flows or sills, and the brec- traverses have been completed in this area and a detailed cias as volcanic tuff-breccias with a matrix that varies later- stratigraphy has notbeen established. Although lithologies ally from lapilli tuff to fine-grained calcareous tuff. are superficially similar to those in the central part of the area, no zones of high-grade mineralization have yet been The breccia sequence is overlain by a second buff to discovered. white-weathering feldspathic unit. It is quite similar to the mineralized, white-weathering quartz-feldspar-carbonate- sericite-apatite unit, however, it generally does notcontain PETROGRAPHE SYENlTES as much sericite or carbonate and is more massivethan the Syenites and melanocratictitaniferous augite sy:nites (malignites) are exposed at the south end of the property. The melanocraticsyenites, which arepresent as large dikes

Plate 12. Typical trachyte, Kechika area, note feldsparphe~rocryst Plate 11. Potassiumfeldspar porphyroclasts in a fine-grained in a matrix predominantly consisting of felted feldspar lathswith carbonate-sericite-feldspar-quartz matrix from a sheared minordisseminated carbonate and opaque, (colour photo, leucosyenite, Kechika area. Long dimension is7 mm. page 135).

30 Geological Survey .8ranch Ministry of EneTy, Mines and Petroleum Resources ”

or elongate stocks, are fineto medium-grained, dark green PETROGRAPHE TRACHYTES to bluish grey rocks with small pyroxeneand feldspar phe- Buff,greyorpinkishweatheringtrachytedikesandsills nocrysts. They contain 40 to 60% microcline, 5 to 20% al- (or flows) are exposed in the central and northernparts of bite and 10 to 20% augite with titaniferous rims. Garnet the area. For the most part, they appearaplitic in hmd speci- (melanite), biotite, sodalite, cancrinite, allanite, magnet- men, however, some varieties contain 2 to 5-millinletre feld- itehlmenite, pyrite, fluorite and apatitehonazite areall pre- spar phenocrysts in an aplitic matrix. In thin section, the sent as accessory phases. Veins or segregations containing porphyritic feldspars are generally polycrystalline and ex- coarse calcite and dark purpleflnoritekbiotitekepidote are hibit both simple and‘checkerboard’ twinning; they appear locally present within the malignites. In the central and to beperthitic in composition. The phenocrystsare present northern parts of the property, melanocratic syenites are in a fine-grained groundmass of felted feldspar ~nicrolites strongly sheared andchlorite rich. with minor disseminated carbonate and opaques(Plate 12). Leucocratic syenites crop outin the southern partof the property, generally as irregular zones within the melano- PETROGRAPHE FELDSPAR-QUARTZ- cratic syenites. They are light grey, medium-grained, mas- CARBONATE-SERICITE ROCKS sive rocks containing35 to 40% microcline and10 to 20% Fine-grained, extremely fissile and micaceon!; phyIlites albite, with fluorite, sodalite, cancrinite, sphene, biotite, py- to massive, white to buff-weathering rocks are commonly rite and pyrochlore present in variable amounts. Crosscut- associated with other alkaline rocks in the central and north- ting calcite-pyrite-fluorite veinlets are common. The em areas of the property. They locally have myklnitic tex- syenites vary from massive and relatively unaltered to tures and contain varying amounts of quartz, carbonate sheared. Sheared syenites contain potassium feldspar por- (generally dolomite, although calcite and iron-rich magne- phyroclasts in a tine-grained recrystallized and altered ma- site have also been noted), muscovite, potassium feldspar, trix Containingabundant clay minerals, quartz, plagioclase, phosphates and pyrite. Massive varieties commonly have dolomite and muscovite(Plate 11). irregular dolomitic patches in a siliceous matrix.

Plate 13. An apatite-rich zonein the quartz-feldspar-sericite-carbonate-(apatite) rocks. The high relief, low birefringent material(medium to dark grey) is all apatite with rare earth enriched phosphate minerals.Low relief material (white to black) is quartz and felispar. The lath shaped grains are sericite. Planepolarized light and crossed nicols.

__ Bulletin 88 31 British Columbia

Locally phosphate minerals comprisein excess of 25% In some samples, potassiumfeldspar porphyroclar.ts are of the sample (Plate 13). In such rocks, a number of phos- preserved in a fine-grained quartz-carbonate-sericie: ma- phate minerals may be intergrown, with apatite the most trix, which suggests that the mylonite had a syenii:ic or trachytic protolith. In other cases, the rocks are very fine common species. Monazite (containing cerium, neodym- grained and completelyrecrystallized; no textural evidence ium, lanthanum, calcium, thorium), xenotime (yttrium of the protolith remains. Fieldevidence indicates that these phosphate, with minor dysprosium, gadolinium and cal- rocks are confomahle to bedding in the hosting limestones cium) and ytirium-thorium-calcium-dysprosium-gadolin-a and were possibly flows or tuff layers. The high degm of ium-bearing phosphate have been identified by scanning electron microscopy. Minor amounts of an iron-thorium- ytrium-calcium silicate mineral havealso been noted.

* mofic syenites * leucocraticsyeniies x shearedleucosyeniles \ 20.00 1 Nephelinite /,, Miaskitic syenite 3 iamilv

/ carbonatiter Ah9 1020 COC- D F (FeOtC0.98 TiOZ) Subolkaiine A rocks

30.00 40.00 50.00 60.00 70.0 Si02 - * mafic syenites * ieucocraticsyenites X sheared leucosyeniter

Carbondite Agpoificsyenite family

qveroge mofic syenite x

XY mafic syenites

j / Subalkaline rocks 0 quarlz-feidrpar-carbonate- Alkali-basalt rericiteapatite rock fomiiy corbonatites 0.00 ,,,,,,,,, ,,,III,,, IIIIIIIII ,,,I, rm 0 rounded cobble breccia 50,'OO 70.0 30!00 40100 60100 0 brown beddedoggiomerate Si07 -k dikes Figure 23. Alkali-silica and agpaiticindex diagrams, Kechika syenites. Figure 24. Major element ternary plots, Kechika igneoussu:te.

- - 32 Geological Survey Bnmch Ministry of Enemy, Mines and Petmleum Resources

TABLE 6 GEOCHEMISTRY OF SELECTED KECHIKA SAMPLES

syenite 43.39 51.05 67.28 29.86 58.35 39.38 46.85 72.17 72.47 65.84 55.0~ 0.76 0.46 0.45 0.02 0.04 1.80 0.08 0.68 0.15 0.49 0.08 19.42 19.86 14.96 7.92 7.44 10.83 7.52 14.67 11.05 17.52 9.63 4.67 2.39 2.22 5.40 4.01 4.69 5.28 1.53 3.96 1.68 1.95 0.26 0.23 0.16 0.200.14 0.170.23 0.43 0.05 0.25 0.170.13 0.01 0.01 0.01 0.M 0.04 3.92 7.23 3.27 1.74 8.011 3.26 1.413.268.0111.74 3.27 7.23 3.92 1.22 0.42 3.88 4.750.570.32 1.03 4.73 4.9~ 0.94 11.6513.17 5.97 5.16 9.55 6.17 9.07 14.12 8.40 12.79 10.90 1.10 0.96 0.87 7.96 3.48 2.98 6.78 6.14 3.24 3.09 0.90 0.15 0.21 0.37 0.20 0.17 0.24 0.95 0.24 4.48 4.34 6.96 6.33 4.92 8.28 9.06 6.60 5.32 8.82 5.52 5.05 8.48 10.90 72 2.78 6.02 3.23 1.84 2.96 2.66 8.13 20.88 11.95 14.20 15.93 2.35 2.14 1.72 12.63 0.36 0.33 0.29 0.26 0.25 0.14 0.16 0.04 0.03 2.42 0.02 0.34 0.07 0.01 0.M ~ -4 - ~ -3 -~ -~ -~ " 98.1497.59 101.27 98.57 96.09 98.19 100.17 96.74 99.96 100.53 92.72 99.88 1w.18 97.20 99.10 99.85 1W.56 99.81 76 180 56 18 168 -30 00 7 11 19 QO 40 150 350 1W 19 354 40 40 10 12 13 110

0.05 0.07 0.08 0.260.38 0.3 0.42 0.64 0.210.160.06 0.18 0.19 0.370.68 0.14 '0.29 1.20 0.43 2.15 6.202.47 10.11 10.00 11.36 11.283.90 7.24 7.19 0.64 3.09 8.293.74 6.92 3.05 1:72 20.71 22.02 24.6020.57 24.34 20.86 19.82 25.44 16.0115.25 10.422.03 6.86 18.23 17.9513.2548.64 50.30 0.14 0.16 0.26 0.26 1.20 0.11 0.130.180.25 0.15 0.23 0.13 0.29 0.26 2.69 0.11 0.13 0.14 3.46 3.19 1.66 3.85 3.110.76 7.490.289.07 6.43 6.40 0.29 10.35 5.96 2.85 0.631.06 0.20 1.82 6.38 7.15 18.66 32.53 30.97 30.83 38.71 20.83 18.58 14.93 3.56 9.31 21.53 7.73 25.86 19.30 13.70 18.20 8.30 0.23 0.02 0.03 0.08 0.12 0.16 0.01 0.09 0.47 0.19 0.25 0.14 96.1396.9496.86 92.82 98.02 100.91 98.491 95.67 98.06 86.54 83.w

_. .. 85 a8 39 95 <49 69 01 43 I60 160 220 63 130 210 27 43 45 430 4w 624 68s 505 275 510 467 660 570 140 71 I50 815 3500 185 I1W 1300 17W 310 1898 522 ISW 310 39w 713 2Mx) I500 130 270 5200 5W 590

" Bulletin 88 33 deformation within these rocks, compared with the other rock types, may be a result of original incompetence, in which case a tuffaceous protolith is favoured. Phosphate- rich rocks are distributed in discontinuouslenses up to :I few metres thick and several tens of metres parallel to oyerall layering.

PETROGRAPHE CARBONATITES Fine-grained igneous carbonate rocks, with a di:;tinc- tive orange-brown-weathering colourare also present :n the Kechika area. They occur as dikes which aregenerally less than a metre wide andcrosscut both other alkaline rocks and the carbonate hostrocks. Volumetrically the carbonatites are an insignificant part of the alkaline suite. The carbonatites are dolomite or ankerite rich (SO%), and contain quartz. Accessory phases include microdine, muscovite, barite, iron oxides, pyrite, fluorapatite, gorceixite, xenotime and an unidentified thorium-calcium- ytrium-iron phosphate mineral. The carbonatites are locally fragmental, containing subangular to rounded lithic :lasts Figure 25. CaO-MgO-FezO,t+MnO carbonatite plot, Kechika. of various rock types.

~ ~~ ~~ .~. . - ~~~~ ~ - CHONDRITE-NORMALIZEDREE PLOT CHONDRITE-NORMALIZEDREE PLOT KECHIKAMAFIC SYENITES KECHIKALEUCOCRATIC SYENITES

Ii 1 1-7 Lo Ce Pr Nd Sm Eu Tb Dy Ho Tm Yb L LO Ce Pr Nd Sm Eu DyTb Ho Tm Yb LI Rare-earthElements Rare-earthElements

Figure 26. (A) Chondrite normalized REE plot - Kechika mafic syenites; (B) Chondrite-normalized REE plot - Kechika leucocratic syenites: (C) Chondrite-normalized REE plot - Kechika quartz-feldspar-carbanate-sericiterocks; (D) Chondrite-normalized REI; plot - Kechika quartz-feldspar-carbonate-sericite-apatiterocks; (E) Chondrite-normalized REE plot - Kechika carhoratites; (F)Chondrite-normalized REE plot - Kechika veins, shearsand alteration zones.

34 Geological Survey Branch Ministry of Energy, Mines and Petroleum Resources

~~~~ ~~~~ ~ ~~ ~ ~~ ~ ~ ~~ ~~ ~~~~~~ ~~~~~~ ~ ~~ ~ ~~ ~~ CHONDRITE-NORMALIZED REE PLOT CHONDRITE-NORMALIZED REE PLOT KECHIKA QUARTZ-FELDSPAR-CARBONATE- KECHIKA OUARTZ-FELDSPAR-CARBONATE- io5 ROCKS SERICITE 105 SERICITE-APATITE ROCKS

104 I@

1 La Ce Pr Nd Sm Eu Tb Dy Ho Tm Yb 1 Lo Ce Pr Nd Sm Eu Tb Dy Ho Trn Yb LC Rare-earthElements Rare-earth Elements CHONDRITE-NORMALIZED REE PLOT CHONDRITE-NORMALIZED REE PLOT KECHIKACAR80NATITES KECHIKAVEINS, SHEARS AND ALTERATION ZONE

104 lo4 4

103

102

1 1 La Ce Pr Nd Sm Eu Tb Dy Ho Tm Yb L Lo Ce Pr Nd Sm Eu Tb Dy Ho lm Yb LI Rare-earthElements Rare-earthElements

Figure 26 (continued) GEOCHEMISTRY middle and heavyrare-earth elements and yttrium. Values Syenites from Kechika havevariable alkalilsilica ratios ofupto1.13%Y~0~,0.30%Nd20~,0.ll%Sm~0~,0.03% (Figures 23a andb: Table 6); however, the ‘average’ lenco- EuO, 0.14% DyZ03 and 0.05% Tb203 are reported by Pel1 syenite plots in themiaskitic syenite field and the ‘average’ et al. (1990). The samples enrichedin middle and heavyrare mafic syenite plots in the nephelinite field, near the miaski- earths give convex-upward, positively sloping chondrite- tic syenite boundary. Syenites are enriched in sodium (Fig- normalized rare-earth patterns (Figure 26d) which are not ure 24a) and moderately enrichedin barium andstrontium typical of carbouatite suites. Almost flat chondrite-no~mal- relative to other rock types in the Kechika area (Table 6). ized rare-earth patterns are occasionally produced by leu- On an AFM diagram, the syenites define a trend subparallel cocratic syenites as well (Figure 26b). to a typical basalt trend, but displaced away from the iron apex (Figure 24b). Carbonatites fall within themagnesio- GEOCHRONOLOGY carbonatite field, close to the boundary with the ferrocarbonatite field and well removed from calcite carbonatites No radiometric dating has been completed on the (Figure 25). Quartz-feldspar-carbonate-sericiteand quartz- Kechika River alkaline rocks. The presence of mylcnites feldspar-carbonate-sericite-apatite rocks are variable in and their distribution suggest that they were emplacedprior composition (Figure 24, Table 6). They are generally so- to orogenesis. Fieldrelationships, in particular the pre.s ence dium poor and calciumor potassium rich. Apatite-rich va- ofbedded agglomeratesand tuffswith sedimentaryinterlay- rieties can contain over 19%PzOs. ers, suggest that the alkaline suite is coeval with the host carbonate sequence,that is, midPaleozoic. As with other alkaline suites, rocks in the Kechika River area are generally enriched in rare-earth elements Clear crosscutting relationships between many of the (Appendix 1). Chondrite-normalized rare-earth element alkaline phases are largely obscured by deformationand, for plots of most rock typesfrom the Kechika area (Figure 26A the most part,the sequence of deformation cannothe estab- to F) showlight rare-earth enrichment typical of carhouatite lished. Mafic syenites in the central part of the area must and alkaline rock complexes. Some carbonatites locally have been emplaced late in the sequence, as clasts of these containing np to 3.77% cerium and lanthanum oxides. Of rocks werenever found in the agglomeratesor breccias. Car- particular interest are the quartz-feldspar-carbonate- bonatite dikes, which crosscut quartz-feldspar-carbollate- sericite-apatite rocks which, as well as containing signifi- sericite rocks and some tuffs, appear to be some 0.:the cant amounts of PzOs, have anomalous concentrations of youngest igneous rocksin the sequence.

36 Geological Survey Bnznch Ministry of Eneqy, Mines and Petroleum Resources

CARBONATITES AND SYENITE GNE,ISS COMPLEXES IN METAMORPH0SE:D PRECAMBRIAN TO EARLY CAMIBR1:A:N STRATA. OMINECA BELT

MANSON CREEK AREA (93N/9) been deformed and metamorphosed to lower amphibolite facies. The hostrocks include psammiticto semipelitic mica Syenite, monzonite and calmnatite occur together on schists,micaceousquartzitesandsomemarbleswhichstrike both the Lonnie(Granite Creek) andVergil (Brent) claims. southeasterly (15Oo-17O0)and dip steeply to the southwest The two showings arelocated 3 kilometres apart, approxi- (7Oo-8O0)on average. mately 8 kilometres east of the placer mining village of The various rock units within each intrusive zone are Manson Creek, 230 kilometres northwest of Prince George. distributed in interfingering lenses (Hankinson, 1958; Exposures are in trenches, between loo0 and 1.100 metres Rowe, 1958; Halleran, 1980). The Lonniecarbonatite is up elevation, on wooded slopes; elsewhere outcrop is sparse. to 50 metres thick and traceable for nearly 500 metres (Fig- TheLonniecarbonatitecanbereachedbyanoldroad,which ure 27);theVergil showing is approximately30 mftres thick is passable by four-wheel-drivevehicle to within 1 kilome- and canbe traced for a few hundred metres.The effects of tre of the showing (latitude 55”40’45”N, longitude alkali metasomatism(fenitization) can be detected for a few 124°23’15”W). The Vergil showing,approximately 5.5 kil- tens of metres beyond the intrusions. ometres from the nearest road, is accessible by helicopter or on foot (latitude 55”42’45”N, longitude 124°25’15”W). CARBONATITES At both showings, theintrusive rocks occur in single, Wovarieties of carbonatite are present within the Lon- northwest-trending, sill-like sheets within uppermost Pre- nie complex: one is aegirine sovite in which the principal Cambrian metasedimentary rocksof the Wolverine Complex components are calcite, microcline, perthite and aegirine; (Lang ef al., 1946). Both intrusive rocks and hostrocks have the other is biotite sovite, comprising calcite, b.iotite and

~~~~~ ~~ ~~~~ _- LEGEND Syenite,monzonite, monzadiorite Aegerine-amphibolefenite Mylonitizedbiotite sovite Biotitesovite Aegerine sovite lnferiayeredsovife and semipelitic schisl WolverineComplex biotite psammit?, semiDeliticschist, minor auartzile

Figure 21. Geological map of the Lonnie (GraniteCreek) carbonatite complex (contours metric), after Rowe,1958

Bulletin 88 37 usually plagioclase. Only biotite sovite occurs at the Vergil tain accessory muscovite, biotite, calcite and apntite. showing. Both the biotite and aegirine sovites are variably Nepheline syenite is also locally present and contains: sig- foliated and containapatite (up to 20%). magnetite and py- nificant amounts of zircon (3-15%). rochlore as accessory minerals. The biotite sovite may also contain zircon; columbite, ilmenorutile and ilmenite have FENZTES also been reported (Hankinson, 1958). At the Lonnie showing, aegirine sovite occurs along the southwestern margin Pods andlayers of fenite occur within both the Lonnie of the and biotite sovite along the northwestern and Vergil intrusive complexes. The fenite is medium to complex dark green in colour and rusty weathering. It consists of margin (Figure 27). The biotite sovite is variably myloni- tized, with the most intense shearing near the contact with aegirine and sodic amphibole (Plate 14) with microcline. the country rocks. Enrichment in zircon, pyrochlore, colum- plagioclase and calcite in varying amounts. The amphibole bite, pyrite and pyrrhotite has been noted nearthe contacts is strongly pleochroic, x -turquoise, y - colourless, z - PNS- of the sovites with syenites (Hankinson, 1958). sian blue, with colour strongest at the rims. It issimilar to the amphibole at the Aley complex, which has beenitlenti- fied as magnesio-arfvedsonite(Miider, 1986, 1987). ‘Trace SILICATE PHASES constituents in fenites include pyrochlore, magnetite and Feldspathic intrusive rocks, monzodiorite, monzonite zircon. and syenite, outcrop as lenticular masses separating the car- The hosting psammitic and semipelitic schists arc rec- bonatite units (Figure 27). These intrusive rocks consist of ognizably fenitized for a few tens of metres beyond the in- potassium feldspar (orthoclase or microcline) and plagio- trusive contacts. Microcline, plagioclase and quartz are clase in varying proportions; plagioclase greatly exceeds major constituents, with aegiriue and arfvedsonite dissemi- potassium feldspar in the monzodiorites, in the monzonites nated throughout, presumably replacing the original mafic the proportions approach equality and potash feldspar silicate minerals. Biotite is present in trace amounts only. greatly exceeds plagioclase in the syenites. All phases con- Calcite, apatite, magnetite and zircon may be present and

Plate 14. Blue pleochroic amphibole (rnagnesio-arfvedsonite) and finer grained aegirine (light green) in ultrafenite, Lonnie area.Long dimension of photomicrograph is2.5 millimetres, (colourpkoto,page 135).

38 Geological Survey €!ranch ~~~ ~ ~~~ ~ ~~~ ~~ ~~ ~ ~ coarse-grained arfvedsonite, magnetite andfeldspar segregations are developed locally.

GEOCHEMISTRY Carbonatites in the Manson Creek area are all true sovites, no magnesio- or ferrocarbonatites were observed (Figure 28; Table 7). Aegirine sovites are depleted in silica and aluminum and enrichedin strontium, relative to biotite sovites. Fenites are notably enriched in iron and sodium, relative to other lithologies (Figure 29; Table 7). With increasing degree of fenitization, that is from recognizable metasediments to ultrafenite, the rocks exhibit a systematic increase in iron and alkalis relative to calcium (Figure 30a) and fenitization appears to be a combination of 'typical' iron-magnesium andalkali fenitization trends. The fenites, even ultrafenites (aegirine and arfvedsonite rich) are enriched in sodium relative to typical pyroxene-amphibole fenites (Figure 30b). J Syenitic rocks are quite vaned in composition (Figures Figure 28. CaO-MgO-Fez03t+MnO carbonatite pht, Lonnie 29and31;Table7)but,onaverage,plotwithinthemiaskitic complex.

TABLE 7 CHEMICAL ANALYSES OF ALKALINE ROCKS, MANSON CREEK AREA

~ ~~~ ~ ~ ~~ ~~~ ~ Syenites and contact syenites Fenite 6 7 6 8 9 1015 1411 13 12 15- Si02 1.7013.70 12.70 7.81 12.00 '14.00 56.7051.09 53.77 32.88 36.44 44.5035.96 38.82 73.15 57.82 Ti02 0.020.670.710.01 0.08 0.03 0.02 0.530.030.400.20 0.660.380.28 0.64 0.83 3.652.48 3.26 11.61 7.46 A1203 0.36 6.79 7.57 2.22 3.06 14.30 16.70 14.93 15.38 11.74 12.14 Fe203T 1.406.21 5.70 0.371.440.80 0.59 5.39 0.57 4.84 2.63 19.6011.66 6.91 4.52 18.63 0.590.37 0.24 0.16 0.28 0.23 0.11 0.260.150.25 0.37 0.24 0.300.340.24 0.115 0.31 2.20 1.850.601.21 0.17 0.12 1.730.181.361.152.482.11 1.13 1.11 2.112 CaO 52.9036.60 36.10 48.29 43.72 16.30 6.09 8.85 9.78 23.12 20.19 10.90 14.5624.21 0.34 1.34 Na20 0.44 1.213.48 0.36 0.99 4.97 6.94 5.57 5.37 3.53 2.46 10.30 5.79 3.99 5.55 10.33 0.12 2.45 2.04 0.49 0.19 5.36 5.84 1.894.821.50 4.43 0.24 0.501.14 1.61 0.ZI 4.417.98 7.48 17.47 17.89 6.5611.48 18.06 0.77 0.46 0.611.05 1.29 1.650.34 0.760.711.13 0.05 0.04 99.27 98.8298.74 98.24 99.8985.93 99.27 99.55 99.59 98.13 ppm Ni <2 <2 <2 2 9 8 4 4 4 337 285 65 5 Cr e20 7 9 <20 e 20 36 52 1415 < 20 <20 15377 24 34 6:: 7 10 10 8 7 8 co 10 10 7 5 3 12 11 9 9<5 2 83831 Sr 120096907 6643 8780 7959 4125 1110 1940 314353606738 1506 2303 5095 233 3:: Ba 9861455 1097 1926 662 263422301321 2752 1191 2479 2084387215129 4: Zr 76 12715477385 2030 10363 1062 170298322756 641 1982324311 Nb <5 78306 2 43 14448831274 358 2465 1589 884 19 253387 17 62 69 54 66 77 46 78 44 33 56 33 44 78 46 77 Y66 54 69 62 53 16 19 36 YO 11 La 24743 135398 345 371 401 347 222 265 88254 102 190 173 22 Ce 600130325176 172 392 470741 398 426 107 286 660 483 673 31 Nd 245179 206 102 35 56 Yb 6.27.7 5.2 3.5 3.8 2.1 sc 30 17 46 4.8 2316.3 16.8 18.5 20.5 31 8.4 7.241 4.1 11.2 37 Ta c2 2 4 <211 c2 37 17 25 9 3 <2 <2 <2 8 <2 Th <6<6<6<6<6 25 28 17 8 <618 6 8 65 244 19 I-LA179C oegirine sovite, Lonnieclaim 12-LA174B ultrafenire, Lonnie claim 2-01242B biotite sovite, Vergilclaim 13-LA197E ultmfenite, Lonnie claim 3-011184 biotite sovite, Lonnie claim 14-LAl79E banded, calcareousfenite, Lonnie claim 4-LA242C white. massive sovite, Vergilclaim IS- l.4178fenitired metasediment with carbonaiite 5-LA252 carbowrite breccia, Vergilclaim veinle:, Lonnie claims 6-l.41978 syenite, Lonnie claim 16- l.41740fenirired mefasediment, Lonnie claim 74.42408 syenite, Vergil claim Samples 1,2,3.6,7,12%- majorelementsnmlyred 8-01250 syenitic breccia, Vergilclaim by ICAP; trace elements by XRF; 9-LAl74A marsive syenite, Lonnieclaim REE by INAA at Bondar-Clegg. IO-LA248 mixed syenitdcarbonatite, Vergilclaim Sampbs4, 5,8,9,10,11.13,14,15,16,- II-LA197D carbonatitdsyenife contact, Lonnie claim Major and tmce elements byXRF.

Bulletin 88 39 %% carbonatites A fenite 0 syenite

trend

Creek

"normal.. fe-Mg fenitetrem

pyroxene amphibod< fenites

Figure 29. Majorelement ternary plots, MansonCreek area Figure 30. Ternary fenite plots, Manson Creek area carbsnatitc carbonatite complexes. complexes. syenite field (Figure 31). These rocksmay contain signifi- GEOCHRONOLOGY cant amounts of zirconium, upto 1.23%, and are enriched The Lonnie andVergil carbonatites contain zircm, py in barium and niobiumrelative to other igneous andmeta- rochlore and other uranium-bearing mineralsthat arc: ame-- somatic rocksin the area. Niobium pentoxidevalues of be- nable to uranium-lead geochronoIogy. Zircons from tween 0.1 and 0.3% have been reported from the Lonnie samples collected from the Lonnie and Vergil carbonatite- showing. Azone in the centre of the property averages 0.3% syenite complexes are generally large crystals that are NbzOs across a width of 7.6 metres and a length of 240 equant and clear. Analyses fromthese samples are ciscor- metres (Vaillancourt and Payne, 1979). dant, but indicate a uranium-lead age of 340 Ma anc. lead.. Rare-earth element abundancesof rocks in the Manson lead ages of 351 to 365 Ma (Appendix2), which is similar Creek area are uniformly low, compared to those at Aley, to the age of the zircons from the Ice River complexin the Kechika River and Rock Canyon Creek (Appendix1) and, Rocky Mountains. Preliminary uranium-lead syste~natic!i as indicated by the shallow slope on chondrite-nomalized do not yield precise ages for these zircons, but do suggest plots, the light rare-earth enrichment is not as marked (Fig- that the Lonnie and Vergil carbonatites were emplaced iu ure 32). Late Devonianto early Mississippiantime.

__ 40 Geological Survey .3ranch Ministry of Energy, Mines and Petmleum Resources

CHONDRITE-NORMALIZED REE PLOl average Lonniesyenite 105 Lonnie & VergilShowings X overagemonzonite - Monson CreekArea . . . Carbonatite A Fanile 104 - syenite . D . . . .

Alkali basalt Subalkaline basalt Alkali rocks

mmrr 30.00 40.00 50.00 60.00 70.01 Si02

Agpaitic 1 !O.OO- syenite La Ce Pr Nd Sm Eu Tb Dy Ho 'lm Yb LI family Mlaskitlc Rare-EarthElements __ syenite family Figure 32. Chondrite-normalized REE plots, Lonnie and Vergil 5.00 showings, Manson creek area. Nephelinite family The alkalic rocks are hosted by high-grade metarnor- phic rocks assigned to the Wolverine complex, 0;' probable 0.00- late Proterozoic age, and are exposed in a 5 hy 10 kilometre area, south andeast of the Manson River, in the Wolverine Ranges of the Omineca Mountains.Within this arxa,a num-

-0 ber of discrete alkalic dikes and dike swarms arepresent, 5.00- associated with alkalic pegmatite dikes or segreg&ions,in- .." Subalkaline rocks trusive breccias and large metasomatic alteration halos U" (fenites); unfoliated, fine-grained quartz morzonite to 0.00 quartz syenite intrusions are also present, but may or may 30.00 40.00 50.00 60.00 70.0 not berelated to the alkaline syenites. The relationship be- Si07 tween the intrusion of alkaline rocks andmetamorphism is Figure 31. Alkali-silica and agpaitic index plots, Lonnie complex unclear fromthe available literature. silicate rocks. (A) Agpiatic index plot - Lonnie complex silicate The area is accessible from good logging roadsthat run rocks; (B) Lonnie - alkali vs silica diagram. along the west side of WillistonLake fromWindy Point,at the south tip of the lake, to Manson Creek. MOUNT BISSON - MUNROE CREEK AREA (93N/9; 930/5,12) ALKALIC DIKE ROCKS Alkalic syenites are exposed in the Mount Bisson - Three types of syenite dikes are present in the Mount Munroe Creekarea of north-central British Columbia (lati- Bisson - Munroe Creekarea: the fzst rich in alkali feldspar; the second containing abundant aegirine-augitc:; and the tude 55'31'00"N, longitude 124"00'00'W), 64 kilometres third a suite of rare-earthelement enricheddikes which con- northwest of the town of Mackenzie (Figure 1). They were tain allanite as the main rare-earth mineral. The alkali ield- discovered in 1986 and 1987by A.A.D. Halleran.The min- spar dikes contain 90% potassium feldspar rimmed with eralogy andfield relationships were describedby Halleran plagioclase, and 10% mafic minerals, predominantly aegir- (1988) andHalleran andRussel1(1990) andare summarized ine-augite. The aegirine-augite dikes contain, 011 average, from these works. 40 to 60% aegirine-augite grains, up to 1.5 centimetres

" Bulletin 88 41 across, 35% perthite, 3% sphene with rare allanite inclu- gioclase (Anzz-uI), potassium feldspar, biotite, chloritz and sions, 1%apatite and traces of allanite, magnetite, chalco- traces of magnetite, allanite, apatite and zircon. pyrite and malachite. These dikes are banded, withthe mafic minerals concentratedin thin, discrete zones. The allanitic GEOCHEMISTRY dikes are also rich in aegirine-augite: they consist of approximately 80% aegirine-augite, 8% potassium feldspar, 5% apatite, 3% allanite and 2%sphene, with accessory calcite and biotite.

PEGMATITES Two types of alkalic pegmatites are described by Hal- leran and Russell (1990),aegirine-augite pegmatites and allanite pegmatites. They occur in zones l to 4 metres wide by in excess of 30 metres long; it is unclear, however, whether they are distinct dikes or, simply, coarse-grained segregations or pods within fenite zones. The aegirine- augite pegmatites contain zoned antiperthite (Anz3), sub- hedral aegirine-augite grains [with inclusions of plagioclase (An34). sphene, hornblende andbiotite], minor perthitic potassium feldspar, occasional elongate quartz crystals and late, fracture-filling epidote. The allanite pegmatites consist of perthite, up to 35% allanite, 5% sphene, plagioclase (Anzs.27). apatite and minor to trace amounts of aegirine- augite, quartz, zircon and opaques.Allanite crystals are 0.03 to 2.0 centimetres in size and commonly occur with sphene and apatite. Late quartz veins, up to 5 centimetres wide, locally cut the allanite pegmatites.

INTRUSIVE BRECCIAS An intrusive breccia zone, over 40 metres long, is exposed in one area. It consists of intrusive clasts supported by a fine-grained, green matrix which contains 25% relic potassium feldspar, 10% plagioclase, altered blue-green amphibole andtraces of sphene and apatite. LEGEND FENITES A e uncertainplutonic rocks Fenitized Wolverine Complex rocks areexposed over &@Gronodik, quartzmonzonite, a broad area. The fenites are generally banded, with melano- tonollle;iocaliy pegmolitic cratic layers consisting of aegirine-augite, sphene, allanite, Hadvnian-Windermere Supergroup apatite and minor hornblende, andleucocratic layers domi- HorsethiefCreek Group, Upper Clastic Unit/Koza Group: granuleconglomerote, nated by plagioclase or potassium feldspar and apatite. psammite;minor peiife and carbonate Banding in the fenites reflects original bedding or layering Horse!hie! CreekGroup, Semipelile/ in the Wolverine rocks which the fenite zones grade into: aAmphlboilte ond Middle Marble unils; melanocratic bands were probably amphibolite or biotite amphibolite,semipelite, marble, minor schist layers while the leococratic bands were probably pelite original quartzofeldspathic layers. Fenites are differentiated HorsethiefCreek Group, Aluminous from hostrocksby the presenceof aegirine-augite and rare- Peiite unit: pslitepredominates: may also containminor amounts of Lower earth element bearing minerals, an increase in alkali feld- GrilUnit spar and a decreasein quartz. Hadrynianand Older (Proterozoic) Maltongneiss: ortho and parogneiss QUARTZ MONZONITESAND QUARTZ SYENITES Geological contact ...... ------Fault ...... Fine-grained, massive, leucocratic quartz monronite Thrust fouit ...... -7-c and quartz syenite intrusions are also present in the Mount Corbonatite/nepheiine rvenite localities ...... 0 Bisson - Munroe Creekarea. They are very fresh in appearance and maybe unrelated to the morealkaline rocks. 'There - are at least four large intrusions (1 by 3 km in size) and a Fig ,ure 33. Geology and CarbonatiteJsyenite localities in the Illue number ofsmaller satellite bodies. Theycontain quartz, pla- Ri\ rer ma.

42 Geological Survey Branch Ministry of Energy, Mines and Petmleurn Resouxes -~ ~~~~~~~~ ~

These valuesrepresent total rare-earth concentrations; how- of Kamloops (Figures 1 and 33). All are sill-like bodies ever, the values are mainly in the light rare earths. Fenites which were intruded prior to the deformation and~netan~or- contain 0.07 to 0.64% light rare earths over widthsof 1to 2 phism associated with the Columbian orogeny. The car- metres. bonatites, syenites and hosting sedimentary rocks beenhave subjected to three phases of deformation (Plate: 15) and GEOCHRONOLOGY metamorphosed to upper amphibolite grade(kyanite to sil- No absolute dating has been done on the alkaline rocks. limanite zone). TheMudLake (83D/3, latitude52c07’55”N. They obviously postdate the Late Proterozoic rocks of the longitude 119°10’44”W), Bone Creek (83D/6: latitude Wolverine Complex;from published data, the timingof em- 52°17’09”N, longitude 119°09’42”W) and Verity (831Y6, placement relative to metamorphism is unclear and anupper limit on the agedifficult to establish. Within the sequence, latitude 52”23’51”N, longitude 119”09’13’W) !showings the syenitic dikes appear to be the latest alkaline rocks em- (Figure 33) occurbelow treeline at elevations bet ween 600 placed as they crosscut both the alkaline pegmatites andthe and 900metres; consequently exposureis limited. ‘ThePara- fenites. dise Lake (83D/6, latitude 52”24’19”N, longitude Quartz monzonites and quartzsyenites probably post- 119°05’47”W) and Howard Creek (83D17, latitude date the alkaline rocks andmay he completely unrelated to 52”23’OO”N, longitude 118”53’26‘W) carbonatites are them; angular fenitexenoliths are reported to occur within above treeline, well exposed and were mapped in datail the quartz-hearing intrusions. From descriptions given, (Figures 34,35a and 35h). these intrusions sound as if theyare postorogenic; however, The Verity carbonatites can be reached by trails and until some radiometricdating is completed, their ages will logging roads whichcross the North Thompson River and remain unknown. intersect Highway 5 at Lempriere Station, approxi.nately 40 kilometres north of Blue River. The Bone Creekshowings BLUE RIVER AREA (83D/3,6,7) are accessed froma logging roadwhich leaves Highway 5 A number of carbonatite and nepheline syenite layers approximately 23 kilometresnorth of Blue River. The Mud occur within the semipelite-amphibolite division of the Lake carbonatite crops out alongthe Red Sands road, which Hadrynian Horsethief Creek Groupin the Monashee Moun- intersects Highway 5, three kilometres north of B lne River. tains near Blue River, approximately 250kilometres north All roads are passable with four-wheel-drivevehicles. The

Plate 15. Fz folds in banded nepheline syenite, Paradise Lake.

Bulletin 88 43 CARBONATITES Three types of carbonatite occur within this suite. One is a whitish weathering olivine sovite which contains predominantly calcite (60-8556). olivine (3-20%) and apatite (2-20%). Accessory minerals which may be present are phlogopite (Plate 16), with either normal or reverse pleochroism (up to 8%). diopside (10% or less), magnetitz, ilmenite, pyrite, pyrrhotite, pyrochlore, columbite, zircon, monazite, allanite and baddelyite. The sovite is usually medium grained andmassive, but locally may contain pegmatitic phases with calcite and olivine crystals 2.5 to 3 centimetres long and magnetiteclusters over20 centimtres in diameter. Zircon crystals up to 3 centimetres long have also been found. The second type is a buff-weathering dolomitic carbonatite (ranhaugite) with accessory amphibole (5-1 S%), apatite (2-10%). magnetite and minor phlogopite.Ilmenite, pyrochlore, columbite and zircon may be present in trace amounts. The amphibolemay be richterite, soda-tremolite, tremolite or actinolite. Apatite and amphibole, within the rauhaugite, define a foliation parallel to both the edg:s of the carbouatite and the external schistosity. Locally,compositional banding with alternating apatite-amphibole-rich and carbonate-rich layers parallels foliation and contacts (Plate 17). Pegmatitic segregations are not found in the ranhaugite, but coarse pyrochlore andzircon crystals ( 1-1.5 cm long) may be present. Separate bands of sovite and rauhaugite occur at Verity, Paradise Lake and Hoxard Creek. Rauhaugiteis present at both the Mud Lake andI3one Creek localities. LEGEND The third type ofcarbonatite, biotite sovite, is found at SYMBOLS Paradise Lake only. It occurs as segregations or pods ;associated with nepheline syenite. Calcite, biotite, apatite and Bedding...... 24y magnetite are the primary constituents and nepheline may F, fold axes ...... 16 - Carbona{ite, ou{crop Minor folds ...... also be present. Fault ...... - 4 Sohene-amohibalite NEPHELINE SYENITES ContourInterval = 30m Nepheline andsodalite syenite gneisses crop out in the ParadiseLakearea (Figure 35). In general, the syenitescom- prise white to grey-weathering, medium-grained, layered yE:&ian Psarnmite,sernipelite, and foliated gneisses, concordant with hostrocks of the andamphibolite Hadrynian Horsethief Creek Group. Layering and foliation are parallel to the margins of the gneisses, to bedding in Figure 34. Geologicalmap of the Howard Creek carbouatite surrounding metasedimentary rocks andto regional lolia- occurrence. tion. These syenites are typically composed of micrccline Howard Creek and Paradise Lakelocalities are reached by (25-35%). plagioclase (An30 - Ana, 25-35%), nepheline helicopter, from Valemount. (10-30%) and biotite (7-15%). Accessory mineralsmay in- Carbonatites in the Blue River area have been exam- clude muscovite, sodalite, cancrinite, zircon and perthite. Trace mineralspresent are calcite, magnetite, pyrrbotitl:, py- ined periodically since the 1950s, for their vermiculite, ura- rochlore and uranopyrochlore. Thesyenite gneisses relo- nium, niobium and tantalum potential. Previous cally migmatitic, with massive, medium to coarse-grained, descriptions are given by McCammon (1951,1953,1955), lensoidal leucosomesthat are composedof either nephdine, Rowe (1958). Currie (1976a). Meyers (1977). Ahroon microcline, plagioclase and sodalite or large perthite crystals (Plates 18 and 19). (1979, 1980), Aaquist (1981, 1982a,1982b, 1982c), White (1982, 1985) and Pel1 (1987). Lithologies are very similar MAFIC SILICATE ROCKS throughout this area and will be described by rock type Mafic and ultramafic silicate rocks are present at rather than locality. Howard Creek (Figure 34). The most common varicty is

44 Geological Survey Branch Ministry of Energy, Mines and Petroleum Resouxes

Geologicalconloct Moraine or talus defined,approx, assumed ...... -""- INTRUSIVE ROCKS Orientationof bedding and parallelfoliation (SI and S2) ...... - F2 Fold axis ...... c- HOST ROCKS Minor F2 folds ...... xp Hadrynian Fault...... -

axidtrace ~ Bondedamphibolite SI syncline, anticline ...... *I Psammlte,semipelite. and 0thin omphibollte layers S2 axialtrace, antiform ...... olcsilicate SI axialtrace ...... Sa \\Il + .i Figure 35. (A) Geology of the area south of Paradise Lake;(B) (Next page) Cross-sectionA-A', area south of Paradise Lake.

Bulletin 88 45 INTRUSIVE ROCKS

Figure 358 (continued)

Plate 17. Well layered carbonatite, Howard Creek. Layering is Plate 16. Phlogopite in carbonatite with reverse pleochroism and produced by compositional variation within the carbonatite andis distinctive orange colour, from Verity. Long dimension of parallel to the marginsof the layer, external sedimentary b:dding photomicrograph is 2.5 millimetres, (colourphoto, page 136). and regional foliation.

46 Geological Survey 3runclr Plate 18. Migmatitic leucosome (tine-grained leucosyenite segregations) presentin layered syenites, Paradise Lake calcite with or without biotite, allanite and apatite The rock is generally coarse grained with pyroxenecrystals exceed- ing 3.5 centimetres in length and sphene crystas up to 2 centimetres long. In the strongly foliated varieties, hom- blende predominates (50-55%), with aegirine-augite, sphene and biotite abundant andcalcite, plagioc1ar.e. apatite, pyrite and sometimes nephelineas trace constituents. At one locality, themelteigiteis transitional to, and locallycrosscnt by, a coarse-grained, massive urtite composed of :25 to 40% nepheline, 10 to 15% potassiumfeldspar, 8 to 15% plagioclase, 8 to 15% aegirine, 15 to 20% hornblende andsphene, biotite and calcite. FENITES Mafic fenites, 1 to 30 centimetres thick, separate carbonatites and host metasedimentary rocks. They vaqfrom medium to coarse grained and massiveto foliated. They are generally composed of amphiboles (hornblende-actinolite, 45-80%), clinopyroxene(generally diopside or augite, up to 35%). apatite and opaques.Accessory minerals which may be present are titanaugite, biotite, plagioclase, sphene, epidote, quartz (remnant) and calcite. In some loca:.itiesa bi- Plate 19. Migmatitic segregations of coarse perthite crystals in otite-vermiculite layer is developed in place of the layered nepheline syenite gneiss, Paradise Lake. amphibole fenites. In all cases the metasedimentary rocks adjacent to the fenites appear unaltered. sphene-pyroxene-amphibolerock or melteigite, which may be layered and foliated or massive. It consists of aegirine- GEOCHEMISTRY augite (approximately 50%), strongly pleochroic horn- The alkaline rocks in the Blue Riverarea shclw distinct blende (x - honey-yellow, y - dark bluish green, z - dark major elementtrends of increasing alkalis from carbonatites forest-green to opaque: 15.30%) and sphene(10-20%). Ac- to syenites, with fenites most similar in composition to the cessory minerals includenepheline, plagioclase, pyrite and carbonatites (Figure 36; Table 8). Carbonatites (b~thcalcite

Bulletin 88 47 British Columbia -

albiie fenite field

Figure 36. Major element ternary plots, Blue River area alkaline ;ocks.

Figure 38. Ternary fenite plots, Blue River area rocks and dolomite-rich varieties) are distinct from marblesin the host Horsethief Creek Group;the carbonatites c0nta.n sig nificantly less silica, aluminum andalkalis than the average marble and are enrichedin iron, phosphorus, strontium and \ rare earths (Table 8). Enrichment in niobium and tartalum also occurs in the carbonatites (Table 8), %Os values of up to 0.46%(Aaquist, 1982b) and tantalumvalues tc.2400 \ ppm (Aaquist, 1982c) have beenreported. Calcite carbona.. tites range fromme sovites to ferrocarbonatites. dolomitic \ carbonatites may be classified as magnesiocarborlatites \ (Figure 37). Fenites are all typical pyroxene-amphibolt: fenites, pIotting withinthe pyroxene-amphibolefenite fields; rnognesio- ferro- o n b o t h N a20-KzO-Fe203 an d C a 0 - N a20i-KzO.. corbonatite corbonatite MgO+FezO3 plots (Figure 38a and b). Syenites frcm tht: Paradise Lakearea are miaskitic, generally compositionally close to the 'average' nepheline syenite (Figure 39a md b). Figure 37. CaO-MgO-Fe203ttMnO carbonatite plot, Blue River Alkaline rocks contain anomalous amounts of rare:-earth area. elements, but not to the extent of many of the comp1t:xes in

- 48 Geological Survey Branch TABLE 8 CHEMICAL ANALYSES,ALKALINE ROCKS, BLUE RIVER AREA

56 3.82 6.60 5.26 2.73 7.64 2.03 12.30 41.0359.2012.W58.W 58.20 42.30 47.01 35.86 44.12 453050.8055.8046.60 31.80 47.10 41.80 60.50 Ti02 0.16 0.80 0.62 0.02 0.02 0.70 0.09 0.85 0.13 0.60 0.44 0.82 0.02 0.29 0.255.65 4.15 218 1.84 0.40 0.23 0.40 0.60 0.64 0.65 0.72 0.15 0.15 on 0.24 0.22 2.226.51 9.62 10.51 I250 22.60 20.8020.10 8.4218.W13.30 5.93 4.88853 9.72 1.03 20.10 4.28 10.70 10.30 4.35 7.356.48 7.618.41 0.305.17 2.627.44 9.40 9.68 2.69 2.20 15.10 8563.67 12.90 5.36 1.10 7.19 11.10 3.31 0.21 0.23 0.24 0.31 0.38 0.21 0.41 0.37 0.240.22 0.20 0.27 0.18 0.01 0.M 0.03 0.41 023 0.12 0.34 0.06 0.15 0.19 0.20 0.03 2.60 6.88 5.59 14.50 19.W 14.80 16.3015.W 2.65 11.12 9.2310.76 2.02 0.W 0.31 0.17 7.14 459 1.40 11.70 1.44 1.W 1290 7.98 4.74 45.40 39.80 40.90 28.10 28.70 32.90 30.64 29.10 20.W16.8115.2642.90 14.40 0.54 0.690.838.20 16.80 13.58 23.10 28.70 23.9 14.90 11.50 5.35 Na20 0.10 0.15 0.15 0.10 0.27 0.11 0.05 4.03 1.11 3.60 3.28 0.40 4.069.70 7.48 8.27 4.462.08 9.52 0.12 1.01 1.13 054 266 3.w K20 4.10 0.38 0.48 4.10 0.25 o.~0.12 0.12 0.59 0.64 153 1.66 3.78 8.W 5.49 5.08 1.201.71 3.50 4.10 1.69 0.97 0.81 0.13 2.71 40.38 35.46 27.12 37.21 20:: ;:$ 20.732.02 4.98 1.75 2.57 1.18 0.90 19.29 0.71 2.12 0.21 -2.44 ~28 098 1.11 0.44 0.23 4.W 4.09 4.W am 4.W $9.78 99.86 97.9897.1097.W lW.11 98.R 99.63 91.1798.18 97.601 lW.48 99.3198.9899.46 99.29 lW.39

'2 4 <2 1 24 6s 58 I7 5 9 92

Porndire&; I Nephelinite

CHONDRITE-NORMALIZEDREE PLOT PARADISE,VERITY, HOWARD CREEK lo5j SHOWINGSBLUERIVER AREA

Carbmatife A Fenile 1 o4

Subalkaline rocks i

0.00' I I I I,, , I,I, I I,, I I I,, , , , , ,I,, , , , , I,,, , , 30.00 40.00 50.00 60.00 70.C Si09

0 nepheline syenite m eDlCore0"S nephelinesyenile

fam ily Agpaiticfamilysyenite fornily

Miaskilic t overage nepheline -"- .- syenite 1 1~11111111111111111111,1111,1 La Ce Pr Nd Srn TbEu Dy Ho Tm Yb LL1 Rare-earthElements Alkalibasalt -- Subalkaline rocks Figure 40. Chondrite-normalized REE plot - Paradise, V:rity, Howard Creek showings Blue Riverarea.

30.00 50.00 40.00 60.00 70.0 Si09

Figure 39. Alkali-silica and agpaitic index plots,Blue River area syenites.

50 Geological Survey Brmch LEGEND 121 Nepheline syenite /Ij Horsethief creek met ore dim en la^ rocks 17 Axial trace of early antiforms I Figure 41. Geology of the Trident Mountain area, Selkirk Mountains (from Pell, 1986b; Perldns, 1983).

Plate 20. Coarse-grainedilmenite segregation in leucosyenite. Trident Mountain. Plate 21. Typical banded nephelinesyenites, Trident Mountain. Plate 22. Leucosyenite dikescutting mafic, biotite-amphibole gneiss, Trident Mountain.

- Carbonalile average 1 family

. 1.00- 1 <. b ?

0 nepheline syenite Alkali bosoltAlkali rn mafic ~(~Icoreou!; family nepheline family syenite

0.00 60.00 73.0 Si07

Figure 42. Alkali-silica and agpaitic indexplots, Trident Mountain syenites.

Plate 23. Xenolith of mafic gneiss inbiotite-rich syenite, Trident Mountain.

52 Geological Survey Branch Minishy of Energy, Mines and Petmleum .Pesources"

the Rocky and Cassiarmountains (Appendix1). Enrichment More recent uranium-lead data have been obtained in light rare earths is greater than in heavy rare earths, as from zircon separates and indicate a mid-Paleoz.oic (1%- indicated by the shallow slope on the chondrite-normalized vono-Mississippian) age of emplacement. A sample from rare-earth element plot (Figure 40). Verity yielded an age of approximately 325 Ma (G.l'.E. White, personal communication,1984); a prelimi!~arydate GEOCHRONOLOGY of approximately 328f30 was obtained from Mud Lake Early attemptsat dating did not provide definitive re- samples (R.R. Parrish,personalcommnnication, 1!)85).Zir- sults on the ageof the alkaline intrusions in the Blue River cons separated from Paradise Lake syenites, which were large, equant andclear, provided slightly discordant analy- area. Potassium-argon dates of 205f8 Ma phlogopite on ses which suggesteda uranium-lead age of apprc7ximately from Howard Creek, and 92.5f3.2 and 80.2S.8 Ma on 340 Ma and lead-lead ages of 351 and 363 Ma (Appendix richterite from Verity were obtained (White, 1982). Suh- 2). sequently, potassium-argon dates of 20of7 Ma on phlogopite and 94.4+3.3 Ma on hornblende fromHoward Creek were obtained (G.P.E. White, personal communication. TRIDENT MOUNTAIN (82M/16) 1984). The young dates (circa 80-90 Ma) are most likely Nepheline syenites were first recognized in e Trident representative of the timing of metamorphism and notthe tk emplacement of the igneous rocks. MountainareabyWheeler(1965)andsubsequentkfmapped byPerkins(l983).TridentMountain(latitude5lo.L~4'N,longitude 118"09' west) is located in the Big Bend cf the Co- lumbia River, about 85 kilometres northeast of R'xelstoke and 20 kilometres southeast of Mica Creek (Figwe1). 'The area is very rugged; the syenites are exposed 011 cliffs at 0 nepheline syenite maficcalcareous elevations of 2200 to 3000 metres, adjacent to largc: icefields nepheline syenite (Figure 41). Access is by helicopter from Revelsbke. The syenite gneisses at Trident Mountain are whiteto grey weathering, medium grained and moderately to well foliated. They are composed of white to pinkish nucrocline TABLE 9 CHEMICAL ANALYSES OF TRIDENT MOUNTAIN SYENITES

Si02 5i.5957.6453.72 41.76 56.66 Ti02 0.020.26 0.80 2.04 41.04 A1203 24.36 15.45 22.35 22.39 21.6922.3922.3515.45 24.36 A1203 Fez03 0.17 13.15 6.24 2.71 81.59 2.71 6.2413.15 0.17 Fez03

MnO 0.01 0.44 0.14 0.08 *>.01 MgO 0.050.46 1.59 3.10 i0.W cao 6.82 0.59 0.33 81.56 0.91 Na206.27 1.72 8.16 7.51 1.39 8.22 7.96 7.52 6.94 1.98 6.94K20 7.52 7.96 8.22

Ni 3 6 11 4 8 CI 21 < 20 19 13 18 CO 16 18 13 14 18 Sr 1234 1713 625 730 1116 BE3 2992 1211 1156 584 1520 zr 210 338 1562 57 43 Nb <5 358 229 249 33 Y 6 22 16 4 2 La 8 197 1 6 21 Ce 16 275 10 22 32 Nd Yb SC 0.1 9.9 0.4

1020 COO Figure 43. Major element ternary plots, Trident Mountain syenites.

- Bulletin 88 53 (25-50%), albitic plagioclase (10-30%) and nepheline(10- River, approximately 15 kilometres northeast of Tcdent 40%). Nepheline generally has an irregular poikiloblastic Mountain. The nepheline-bearing lithologies display a texture and is often partially altered to clay minerals. Green strong foliation, conformable to the surrounding metasedi- to olive-pleochroic biotite is commonly the mafic silicate mentary rocks, which are assigned to the Lower Cambrian phase present and comprises from trace amounts to more Hamill Group. The only known outcrops of this intrusion than 30% of the rock. Locally,coarse-grained aggregatesof were in the Sullivan River delta, which is now flooded by randomly oriented biotite crystals are developed. Greenish the Mica Dam reservoir. acmitic pyroxene has also been reported from nepheline- rich phases (Cnme, 1976a). Accessory minerals may in- GEOCHEMISTRY clude sodalite, cancrinite, calcite, apatite, sphene, ilmenite, The leucosyenites at Trident Mountain are miarkitic pyrochlore and zircon (crystals up to 1.5 cm in size). I1- (Figure 42), and are compositionallysimilar to the ‘aver.age’ menite segregations, 20 to 40 centimetres in size, are some- nepheline syenite. Mafic calcareous phases plot withi:1 the times present (Plate 20). Local pegmatiticsegregations are nephelinite field. Melanocratic andleucocratic varieties ap- sporadically developed. parently form a cogenetic sequence (Figure 43). The The syenites occur as a concordantlenticular mass high syenites are locally enriched in strontium, barium, zirco- on the slopes of Trident Mountain andadjacent ridges. The nium andniobium (Table 9).Rare-earth elementconcentra- hostrocks are psammitic andkyanite-bearing pelitic schists tions are generally low. Chemically (and mineralogically) (with rare calcsilicate bands) of the Hadrynian Horsethief they are very similar to those at Paradise Lakein the Blue Creek Group and are exposedin the core of an early isoclinal River area. antifonn which is refolded by later upright to overturned structures (Perkins, 1983). The syenites display composi- GEOCHRONOLOGY tional layering and afoliation parallel to the margins of the Two zircon fractions from the Trident Mountainsyenite body, the axial plane of the antifonn and bedding in the were collected and hand picked. They consisted of clear to metasedimentary rocks. The layering is defined by leu- slightly cloudy, equant, multifaceted roundish grains. The cocratic (biotite less than 10%)and melanocratic (biotite two analyses were somewhatdiscordant and, because cf the 30-40%)phases (Plate 21) withoccasionalcalcareouslayers low uraniumcontent, it has been interpreted that both meta- (sovitic sweats?). Leuococratic syenites are the most abun- morphic and igneouszircons are present. This is also sng- dant phase. gested by the fact that a number ofthe crystals havepefiztly clear rims surrounding cloudycores (Le., two generaions Melauocratic syenite gneisses rich in amphibole, bi- of zircon growth). Alsothe morphology ofthe grains is typi- otite and sphene are also present at Trident Mountain, but cal of metamorphic zircon (R.R.Parrish, personal conunn- were not seen in outcrop. They are cnt by dikes of lenco- nication, 1987). Ona concordiadiagram (Appendix 2) 2. line syenite. Contacts between the mafic gneisses and syenite joining the two analytical points has upper and loweri nter- dikes are sharp (Plate 22). Xenoliths of country rock or mafic orthogneiss were observed in the melanocratic cepts of 378+7 Ma and 138f9 Ma). The 378 Ma date is syenites. The xenoliths have very diffuse contacts, suggest- consistent with the Devono-Mississippian age obtained ing reaction with, or partial digestion by, the syenitic magma from Paradise Lake syenites which resemble the Trident (Plate 23). Mafic gneisses apparently represent an early Mountain gneisses, and withinterpreted ages of other car- phase of intrusion, cut by later leucocratic nepheline bonatite complexes in British Columbia. The 138Ma date syenites. may be indicative of a period of resetting during a Jnrwsic metamorphic event. Uranium-lead data on pyrochlore yield Another mass of nepheline syenite is reported (Fyles, a 60 Ma date (R.R. Pamsh, personal communication,1,387) 1959, 1960; Cume, 1976a) at the mouth of the Sullivan which may indicate a late metamorphic resetting.

54 Geological Survey Brmch Ministry of Energy, Mines and Petroleum .en=

CARBONATITES AND SYENITE GNEISS COMPLEXES ASSOCIATED WITH COIRE

GNEISSES IN THE OMINECA mrr"

Intrusive and extrusive carbonatites and syenite gneiss MOUNT COPELAND NEPHELINE bodies occur within a mixed paragneiss succession along SYENITE GNEISSES (82M/2) the margin ofFrenchman Capgneiss dome (Figure 44),one of several late domal structures near the eastern margin of The Mount Copelandsyenite gneisses crop out along Hren Creek andon the slopes south of Mount Copeland,in the Sbnswap complex in southeastern British Columbia the Jordan Riverarea (Figure 45) on the southeastern flank (Wheeler, 1965). The domeis exposed as a window between of the Frenchman Cap dome (latitude 51"05'N, longitude the Columbia River fault to the east and the Monashee 118"25W) approximately 25 kilometres northwest of d6collement to the west (Read and Brown, 1981). Revelstoke. Thealkaline rocks arereadily accessible by an The core of Frenchman Cap dome comprises mixed a old mine road which leaves the TransCanada Highway just paragneiss and orthogneiss succession of probable Aphe- west of Revelstoke. During the summer of 1985 this road bian age. It is basement to an unconformably overlying was passable with a four-wheel-drive vehicle to within 2 'mantling gneiss' or autochthonous coversuccession, com- kilometres of outcroppings of syenite gneiss. prising a basal quartzite and overlyingpelitic and calcareous Alkaline rocksin the Mount Copelandregion werefirst rocks. The autochthonous cover successionhosts the car- identified byWheeler (1965)in the courseof regicmal m.ap- ping. The area was studied in detail by Fyles (1970) and bonatites and syenite gneisses. Its depositional environment Curie (1976b). The readeris referred to previou!; authors, is interpreted as shallow marine or platformal (McMillan, in particular the work by Cume (1976b), for delailed de 1973; Hoy and McMillan, 1979;Brown, 1980). scriptions; much of what follows is summarized From that The ages ofthe mantlingparagneiss successionand car- work. bonatites have not yet been unequivocally established. The Mount Copelandsyenites (Figure 45) arc exposed Based on regional correlations with platformal rocks to the in a large antiformal structure and have been sutljected to east, a numberof authors (Wheeler, 1965; Fyles, 1970; HOy more than one phase of folding. They are apparently con- and McMillan, 1979) tentatively assigned Eocambrian to cordant with metasedimentary hostrocks. All contacts within the igneous rocks appear to be gradational. Three early Paleozoic ages to these rocks. Recent lead isotopic alkaline rock units have been defined; a basal ~lephe'line data from a syngeneticlead-zinc layer within the upper part syenite gneiss, overlain by alkaline amphibolite, ahich isin of the succession support Eocambrianan to Early Cambrian turn overlain by calcareous and saturated syenite:;. The al- age for that part of the sequence (HOy and Godwin, 1988). kaline rocks intrude micaceous quartzites and c~lcsilicate Uranium-lead systematics on a syenite intrusive into the gneisses of the Frenchman Cap autochthonous ,:over se- lower part of the sequence suggest late a Precambrian (circa qnence. The metasedimentary succession has been corre- 770 Ma) agefor the syenite (Oknlitch e#al., 1981); this sug- lated with a similar successionin the Perry River and Mount gests that the lower part of the mantling gneiss succession Grace areas (HOy and McMillan, 1979; brow^,^, 19110). Based on these correlations, it appears that the gneisses at must be younger than 780 Ma. Mount Copeland lie stratigraphically beneath the Mount Two phases of folding are prominent in the mantling Grace extrusive carbonatite. Postorogenic lamprophyre gneiss succession andvarious generations of minor foldsare dikes are also present in the Mount Copelandarer.. also developed (Fyles, 1970; McMillan, 1970). All phases of folding deform boththe extrusive and intrusive carbona- NEPHELINE SYENlTE GNEISSES tites and the syenite gneisses. Amphibolite facies regional The nepheline syenite gneisses (unit A1 of Cuirie, metamorpbism alongthe margin of Frenchman Cap dome 1976b) contain nepheline in excess of 10%.The:l may be weakly to strongly foliated, and locally have aspectacularly has produced sillimanite-kyanite, sillimanite and sillimanite -potassic feldspar assemblagesin developed augen texture with large porphyroblastr: of pelitic rocks. Calcsilicate nepheline andalkali feldspar in a fine-grained groundmass. assemblages contain diopside, garnet and actinolite. Car- The augen gneisses (unit Ala) are found in outlying areas bonates andcarbonatites are recrystallized to medium to lo- and as lenticles within the calcsilicate hostrocks; they are cally coarse-grainedgranoblasticmarbles (HdyandKwong, mesocratic rocks with a faint purplish tinge and are pre- 1986). dominantly composedof nepheline, alkali feldspar, perthite,

Bulletin 88 55 British Columbia -

Figure 44. Geology of the Frenchman Cap area (from Hoy and Kwong, 1986).

56 Geological Survey $:ranch LEGEND Talus, glacialdeposits, recent stream gravels snow and iceaccumuiations

100, biotileschist and gneiss with prominent augen gneiss zones, abundantpegmatite; lob, porphyroblosticgranite gneiss Eiockywhite quartzite containing biotite schist

Purplishquart-diopside-biotite gneiss with glossyquortz layers, rare morbie lenlicler; Ea bronzymica schist with quortrile and calssilicate layers Grey green to whitesyenite gneiss; Ah, caiwreous

Alkolineamphibolite, amphibole-biotite schist, clmphiboiecaicite pegmatite

Finelybanded muscovite quartzite with mica schistintercalations

Grey biotitegneiss and quortzitewith meionocrotic biotiteschist intercalotions Eioskywhite quartzite and misoceous quartzite withdeformed pebble conglomerate layer near base

100

SYMBOLS

(defined,Approximate. assumed) ._...... -"- - " Rood ......

(from K.L. Currie. 1976 GSC Memoir 265) Figure 45. Geological map, Mount Copeland area calcite, biotite and fluorite. Cancrinite is often present mar- ALKALINEAMPHIBOLITE ginal to nepheline grains. Accessory mineralsinclude tour- A thin lens, or numerous parallel lenses, of alkaline maline, apatite, sphene, riebeckite and rarely, poikilitic ‘amphibolite’ (unit A2) can be traced for more than aegirine. 10 kilometres. It consists of gneissic and fissile medium to The corepart of the nepheline syenite (unit Alb) con- coarse-grained mesocratic to melanocratic rocks. Aeg;rine, sists of a weakly foliated, pale pink leucocratic rock that biotite and sphenearethemajor constituents; calcite, apatite and potash feldspar may be present in minor amounts Pla- contains nepheline, potash feldspar and albite with lesser gioclase is rare and, where present, often partially rep: aced aegirine and sphene. Accessory minerals include calcite, by scapolite. present as small grains along narrow seams, fluorite, garnet and zircon. Tracesof biotite, muscovite andcancrinite may GREY SYENITIC GNEISS also be present. The strongly alkaline rocks (units AI and A2) arcsnr- The third type of nepheline gneiss (unit Alc), which rounded by a thick shell of less alkaline rocks. Three prin- may be transitional to the nepheline-free syenites, is creamy cipal types are recognized: a fine-grained greenish grey to buff weathering andexhibits the best-developed gneissic syenite with slight gneissic banding (unit A3a);a white, apli- foliation of all the nepheline syenites. Microcline, perthite tic lencosyenite (unit A3b); and buff a to pale pink, me flum to coarse-grained syenite (unit A3c). and fine-grained nepheline, commonly replaced by can- The fine-grained, greenish grey syenite is dominatedby crinite and thompsonite, are the dominant constituents. plagioclase (An39 and potashfeldspar. Themostprominent Phlogopitic mica is the principal mafic mineral, although it mafic mineralis biotite, although a diopsidic pyroxene may is rarely present inamounts greater than 5%. Small amounts also be present. Calcite, sphene and epidote are common. of aegirine and hastingsite may also be present. Accessory Accessory minerals include apatite, muscovite and zeJlite, a minerals include sphene, apatite, calcite and specularite. either analcite or thompsonite. Quartzis very rarely fcnnd. TABLE 10 CHEMICAL COMPOSITION OF SELECTED ROCKS FROM THE MOUNT COPELAND SYENITEC0MPLE:X

~ WI % Alc A2 A3a A3b A3c D ~ Si02 54.11 44.1848.90 57.97 53.60 49.09 39.70 39.73 54.97 Ti02 0.49 5.49 3.07 2.53 1.630.47 1.28 1.24 0.62 A1203 21.69 11.307.51 18.48 18.0815.40 13.50 14.44 21.82 Fe203 2.48 1.308.06 0.22 0.04 2.60 2.60 2.71 3.81 FeO 0.626.10 0.5110.207.17 7.20 0.49 5.40 4.92 MnO 0.11 0.150.37 0.05 0.160.23 0.14 0.14 0.12 MgO 0.19 7.76 8.40 2.81 0.116.000.29 7.60 7.34 CaO 3.01 9.6810.10 6.53 4.80 11.57 11.00 9.41 2.51 Na20 5.85 2.303.692.63 2.509.324.331.321.90 K20 7.21 7.47 7.53 0.91 4.30 6.20 HZ0 0.30 0.88 0.49 4.72 0.50 1.11 1.26 1.21 2.20 0.82 0.18 1.70 2.29 1.90 2.03 c02 0.12 0.80 0.23 1.11 0.20 0.10 0.24 0.26 0.60 0.88 5.22 0.10 0.28 8.20 7.09 0.01 0.03 0.02 0.02 0.02 0.03 0.01 0.59 0.28 0.49 0.14 0.37 0.01 1.68 1.77 ~ P205 3.77 Total 39.47 99.85 100.36 99.71 100.5* 99.99 99.43 99.77 100.4* 99.94 99.71 100.1* 98.98 99.3* 98.34

ppm 4.62 7.50 ~ 11.39 9.37 1.60 ~ 3.20 ~ 5.101 7.621 Ni 1 1 Cr co Sr 1900 1800 940 - 1200 3100 - 3400 - Ba 1200 320 280 - loo0 33 - 130 - ZI 16002200 600 - 2902400 - 2700 - 510 140 260 340 200 340 260 Nb140 510 - 300 - 470 -

230 39 100 Y 39 230 6.8 - 5.8 ~ 9.5 - 15 - La - 270 44 83- 34 - 500 - Ce 1300 99 - <500 510- 780 - 540 - 820 - Nd 310420 550- 330 - 630 - 270 - Yb - 11 6.5 ~ 150 - 7.2 7.6 5.6sc 7.6 7.2 -i 31- 7.8 - 12 <4 - 6.8 - ~ *From Currie (1976a) From Currie (1976b) -all other analyses Ala - leucocratic nepheline augen syenites; Alb - nepheline syenite gneisses, pink and white; Alc -pinkand grey nepheline-biotite syenites A2 - black alkaline amphibolite; A3a - grey granular syenite; A3b - grey syenite; A3c-greenish granular syenite; D - ocellar biotite lamprophyre dike.

58 Geological Suwey Blanch Ministry of Energy, Mines and Pefmleum Resources"

The aplitic leucosyenites contain albitic plagioclase, be present in combination or separately. Zircon, magnetite potash feldspar, muscovite and either calcite or diopside. and apatite are common accessoryminerals; tourmaline and Biotite, zircon, apatite, pyrite and molybdenitemay be pre- fluorite have also been noted. sent in trace amounts. This rock is the host of the Mount Copeland molybdenitedeposit. In the vicinity ofthe deposit, GEOCHEMISTRY molybdenite is more abundantthan elsewhere andepidote Thenepheline syenitegneisses show amarkeclincrease is present. in silica content fromunit Ala to unit Alc (Table 10) that is The third group of syenites are, in general, buff to pink proportional to a decrease in modal nepheline. Unit Ala is in colour andgneissic. This is an extremely heterogeneous also richer in alkalis than the other nepheline gneimes. Unit unit, exhibiting a great variation in mineralogy. Potashfeld- A2 has an extremely high soda and potash content(Table spar and albitic plagioclase are generally present. Calcite or fine-grained aggregates of analcite and cancrinite are found 10) for normal igneous rocksof comparable silicz. and alu- in some specimens.Biotite, aegirine and a hastingsitic am- mina contents. Cume (1976b) feels this could be rlttributed phibole are the mafic mineralswhich may occur; they may to fenitization. Major element data (Table 10) fo~.syenites in unit 3A indicate that they are only mildly alkaline. The ~ ~~~~~~ ~ ~~ ~~~~~~ ~ ~ ~ ~~~ ~~~~~~ syenites at Mount Copeland all tend to be enriched in in- 0 A1 Syenites V A3 Syenites compatible elements(e.& Sr, Zr,Nb, Y and REE, Table IO).

Subalkaline rocks L \

30.00 40.00 50.00 60.00- 70.1 Si07

0 A1 Syenites 0 A3 Syenites

Corbonatite 0 A1 syen fer Agpaiticsyenite fomily 0 A3 syen fer

Alkalibasalt family Subalkaline rocks

0.00 30.00 40.00 50.00 60.00 70.' Si09 Figure 46. Alkali-silica and agpaitic index plots, MountCopeland syenites. Figure 47. Major elementternary plots, Mount Copelan syenites.

Bulletin 88 59 British Columbia -

On agpaitic index and alkali-silica plots, nepheline up-section to the south. The carbonatites consist of dixon- syenites (unit Al) predominantly plot within the miaskitic tinuous lenses associated with mafic (pyroxene-amphhole) syenite field. The leucocratic nepheline augen syenites (unit and syenitic fenites. Within the volumetrically more abun- Ala) fall within the agpaitic field on the alkali-silica plot, dantfenites,carbonatites may occuras relatively thick, buff- but are closer to the miaskitic field on theagpaitic index plot weathering, foliated and laminated layers (Plate 24); as (Figure 46). The bordering syenites (unit A3) contain sig- swirled, discontinuouslenses (Plate 25);or as small, irregu- nificantly less alkalis, and plot in the miaskitic syenite to lar coarse-grained pods. alkali basalt (alkaline gabbro) fields. The bordersyenitesare The carbonatites are sovites and consist of 70 to90% also somewhat enriched in calcium, magnesium and iron calcite and variable amounts of sodic amphibole (rie- relative to the nepheline syenites (Figure 47). beckite), apatite and phlogopite. Phlogopites may di:;play reversed pleochroism. Sphene, aegirine, plagioclase, mag- GEOCHRONOLOGY netite, pyrrhotite, pyrochlore, chalcopyrite, pyrite, The isotopic ratios resulting from lead and uranium molybdenite and ilmenite may be present as accessory min- analyses on zircons separated from Mount Copelandsyenite erals. gneisses yielded an early Hadrynian age of emplacement, circa 770 Ma (Okulitch et al., 1981). Subsequent analyses FENITES -PERRY RIVER AREA (R.R. Parrish, personal communication, 1986)are in agreement. Fenites are well layered, probably reflecting oripinal compositionalvariations in sedimentary strata. Three lypes are recognized; mafic pyroxene-amphibolefenite, syenitic CARBONATITES AND ASSOCIATED albite - potassium feldspar fenite and albite fenite. The ROCKS, WEST FLANK, FRENCHMAN mafic fenite isby far the most abundant;jt has gradational CAP DOME (82M/2,7,10) contacts with interlayered albite fenite and sharpcoctacts with syenitic fenites (Plate 26). Remnant metasedimmtary Carbonatites alongthe western margin of the I'rench- calcsilicate gneiss, quartzofeldspathic paragneiss and nunor man Cap dome in the Perry River area (latitude 51°15'N, longitude 118"41W Figure 44) were originally described by McMillan (1970) and McMillanand Moore (1974). Wo types were recognized.Type 1carbonatites are conformable with bedding inmetasedimentary hostrocks andhave metasomatic envelopes whichmay extend from l to more than 30 metres beyond the intrusive contacts. They are interpreted to be sills or dikes. Type2 carbonatites are concordant bodies, associated with whitemarbles, which have no contact alteration zones. They crop outin strata which overlie those hosting Qpe 1 carbonatites. Detailed mappingin the Mount Grace area north of the Perry River (latitude 51"27'N, longitude 118"49W, Hoy and McMillan, 1979) led to the discovery of new occurrences of the Type 2 carbonatite layer, referred to as the Mount Grace carbonatite (Hoy and Kwong, 1986) and confirmedthe suggestion that it is an extrusive layer. More recent work (Pilcher, 1983; Hoy and Pell, 1986; Hoy, 1988) has shown that intrusive carbonatites occur at two stratigraphic levels. Anew occurrence (Pilcher, 1983) is located stratigraphically above the Mount Graceextrusive layer and is referred to as the Ren, or Ratchford Creekcarbonatite(latitude5l022'N, longitude 118"44W). A detailed account of carbonatites on the west flank ofthe Frenchman Cap Domeis given in Hoy (1988) and the reader is referred there for additional information. PERRY RIVER INTRUSIVECARBONATITES (82Mf7) Several lenses of intrusive carbonatite are recognized in the Perry Riverarea (McMillan andMoore, 1974). They occur low in the mantling gneiss stratigraphy, locally within a few metres of the core gneisses. These occurrences appear to be pat of a single continuous zoneat least 4 kilometres in length (Figure 3 of McMillan and Moore, 1974)that is Plate 24. Intrusivecarbonatite band (light grey) surroundedby dark concordant with layering, but on a regional scale may cut amphibolite fenite and some grey syenitic fenite, Perry River area.

60 Geological Survey Bi.anck ~~ ~~ Plate 25. Swirled carbonatite (light colour) in amphibolefenite, Perry River area.

Plate 26. Interlayered amphibolitic feni't (dark) and syenitic fenite (light), Perry River area.

Bulletin 88 61 British Columbia marble layers occur withinthe fenites. In general, the contacts between mafic fenites and quartzofeldspatbic parag- neisses are sharp, whereas those with more calcareous strata are gradational. Toward the centre of the fenitized zones, paragneiss layers may be present but not calcsilicate gneisses. These relationships suggest that fenitization is se- lective, preferentially affecting more calcareous layers and only with increasing intensity affecting quartzofeldspathic strata to produce syenitic fenites (Hoy, 1988). Pyroxene amphibolefenites are dark greento black and may he massiveor foliated. They consist primarily of aegirine-augite, or rarely, aegirine, sodic amphibole, spheneand biotite. Biotite content ranges from trace amounts to over 50%. Calcite, apatite, plagioclase (albite), epidote, zircon, chalcopyrite, magnetite and ilmenite may be present as accessory minerals. Potassium feldspar and nepheline have also been noted (Hoy, 1988). Pegmatitic lenses consisting of calcite, amphibole, pyroxene, enhedralsphene, magnetite and ilmenite are common throughoutthe fenites. Individual crystals of these minerals may be in excess of 7 centimetres long. The mafic fenites are locally interlayered and gradational with leucocratic fenites (or albitites) consisting of approximately 90% albite with aegirine-augite and minor amounts of biotite, sphene, apatite, epidote, microcline, magnetite, and locally, coarse molybdenite. Syenitic fenites are foliated, compositionally handed and contain rare thin metasedimentarylayers and occasional small discontinuous carbonatite lenses. They are composed of 70 to 80% plagioclase (andesine) and microcline in varying proportions. TNe syenites are less common that monzonites (microcline is generally less abundant than Plate 27. RatchfordCreek (REN) carbonatite(light grey) plagioclase). Principal mafic minerals areaegirine or aegir- interlayered with amphibolitic fenite (dark grey) and conlaining ine-augite with or without biotite. Calcite, muscovite, fenitized country rock fragments (grey),(colourphoto, pug,? 136). sphene, magnetite, apatite, chalcopyrite and allanite are common accessoryminerals. Variable amounts ofnepheline may also be present.

RATCHFORD CREEK(REN) INTRUSIVE INTRUSIVE SYENITE- PERRYRIVER AREA CARBONATITE (82M/7) (82M/7,10) A large intrusive syenite body crops out in the Peny The Ratchford Creekcarbonatite is a concordantunit River area(see Figure 44). It is a concordant unit, up 1.0 300 at least 3 kilometres in length and, on average, 10 to 30 metres thick and 12 kilometres long (McMillan,1973), tbaf. metres thick. It is associated with pyroxene-amphibole is internally foliated and layered with alternating bands 01 fenites similar to those occurring with Type 1 carbonatites. syenitic and feldspathoidal rock. Country rocks along its It crops ont south of Ratchford Creek, in the core of the margins are metasomatically altered; a rusty zone en~iched Mount Grace syncline (Figure 44) andis intrusive into strata in feldspar,pyroxene, muscoviteandor pyrrhotite is devel-. which overlie those hosting the other known carbonatites oped adjacent to the syenite. The syenite gneiss infruded (intrusive and extrusive) and syenites. strata which underlie those hosting the extrusive carbona The Ren carbonatite weathers to a mottled orange- tite. brown colourand bas well-handeda to salt-and-pepper tex- The main minerals in the syenite are microcline:, per-. ture. It is intimately intermixed with pyroxene-amphibole thite, plagioclase (albite to labradorite) and nepheline. Ap fenites and locally contains weakly fenitized inclusions of proximately 60% of the rocks contain nepheline, with or country rock(Plate 27). The carbonatite comprises, on av- without feldspars. Biotite is the predominant maficmineral erage, 60 to 80% carbonate minerals(calcite and dolomite) aegirine or aegirine-augite may also be present. Acc~:ssory and 10 to 30% apatite, with accessory biotite, magnetite, minerals include muscovite, phlogopite, calcite, cancrinite, amphibole, pyroxene and sphene,and minorpyrrhotite, py- apatite, sphene, zircon, allanite, pyrochlore, grossnlsr gar.. rite, sphalerite, chalcopyrite, pyrochloref?) and monazite(?) net, fluorite, molybdenite, magnetite and pyrrhotite. (Pilcher, 1983). (McMillan and Moore, 1974).

62 Geological Survey i?ronch Plate 28. Part of the thickened sectionof the Mount Grace extrusive carbonatite; the whole cliff is part of the carbonatite zone; note large syenitic inclusions immediatelyabove the person. MOUNT GRACE EXTRUSIVE CARBONATITE (82M/7,10) The Mount Gracecarbonatite layer averages 3 to 5 metres in thickness.Locally, it narrows to less than a metre and near its mapped northernlimit (Figure 44). it isestimated to be greater than 20 metres thick (Plate 28). An associated increase in clast sizes here indicates close proximity to a source or vent area. Although in most places it is a single layer, it locally comprises a main layer plus a number of thinner layers separated by paragneiss and marble. It has been traced or projected beneath overburden for a strike length of at least 100 kilometres (Hay, 1988). The contacts of the Mount Gracecarbonatite with overlying and underlying calcareous gneisses are sharp, hut in places they grade through approximately1 metre into grey-weathering, massive to thin-bedded calcite marble. In contrast with intrusive carbonatites in the Perry River area, it has no fenitized margins. Detailed descriptions of the Mount Gracecarbonatite have previously been published (Hoy and Kwong, 1986; Hoy and Pell, 1986; HOy, 1988) and onlya brief reviewwill be presented here. In the field, the carbonatite is recognized and characterized by an unusual pale to medium brown weathering colour. Grains of dark brown phlogopite, colourless apatite and needlesof amphibole weatherin relief. Pyrrhotite, pyrochlore and zircon are locally developed accessoryminer- Plate 29. Interbedded grey sedimentary marble (light ):rey) with als. Monazite, barite, strontianite and possibly rare earth buff carbonatite agglomerateand tuff (darkergreys) layers;Mount carbonate mineralsare present in trace amounts. Grace carbonatite nearBlais Creek.

Bulletin 88 63 TABLE 11 CHEMICAL ANALYSES OF ALKALINE ROCKS, WEST FLANK, FRENCHMAN CAP DOME

Mount Grace P,, River Ren InWsIve Nepheline syenite gneiss carbanatite inrmsivs carbonatitn cartonatite 5.1 5.1 5.15,1 5.1 5.1 5.15.1 51 Z2-L 2- 2 2 2- -2- -~ I51.44 57.34 46.18 55.67 51.3341.77 53.02 & 6.77 0.39 6.38 0.79 4.10 1.51 4.57 0.85 4.15 0.27 0.30 0.940.28 0.380.52 0.21 0.60 1.32 <0.01 0.86 0.03 0.05 0.06 0.04 0.04 0.06 24.42 22.98 28.1123.59 23.57 31.71 27.12 19.76 0.36 0.16 1.57 0.30 0.91 0.22 0.55 0.07 0.72 1.40 0.59 4.080.630.44 0.29 1.14 4.10 4.14 0.38 4.66 0.68 1.20 3.45 2.87 2.71 3.29 1.32 1.33 2.57 1.45 2.37 1.49 0.46 1.30 .. 0.10 0.07 0.29 0.09 0.09 0.10 0.09 0.15 0.38 0.44 0.440.17 0.99 0.310.43 0.410.43 0.15 0.24 1.12 0.15 0.79 0.46 0.31 0.37 2.38 0.46 1.850.62 0.10 6.3017.30 16.6915.40 4.23 0.59 4.63 2.06 2.973.47 6.33 2.79 45.34 51.0442.72 52.44 45.2943.82 31.05 33.8332.86 9.44 5.06 3.00 4.12 7.5112.23 4.24 6.04 0.37 0.13 0.64 0.14 0.370.080.24 0.04 0.16 3.55 10.183.555.80 8.99 6.414.706.69 10.9010.30 43 0.38 1.08 0.97 0.63 1.41 1.741.410.63 0.97 1.08 1.23 1.53 0.501.420.36 0.50 2.49 0.35 2.17 0.12 1.22 0.41 0.530.411.220.12 2.17 0.35 2.49 0.62 0.7040.72 31.10

0.16 0.60 0.10 0.36 0.1s ~ 0.31 ~08COS 0.06 0.06 %.0s~l00.00iw.l2 99.02 99.4698.54 101:70 Im7r 9.54 98.6898.63

.". "" .. ." ...... _. - - 33W57W 46M 54M) 6600 58W 16w 31W2103 1wO 5188462842714828 .." - .3500 28W31W 35003203 36w1626761133 213 1205 2539 12171155 1403LIS023W 3700 1915 2540 2185 - . . - 'i - - .. - 297208 % 92 108 IZW - 2380 - 12w lZm . - .

2.94 1.32 0.880.210.41 0.847.4416.614.645.30 5.891.611 4.074.08 2.50 5.76 2.38 3.39 6.46 3.21 0.791 8.% 0.37 0.07 0.03 0.02 0.060.02 -. 2.680.03 0.24 0.160.360.080.75 0.0s 0.35 0.05/ 3.191.813.322.12 0.99 1.82 97.79 100.69 101.09 98.80 99.59 99.01 101.45 99.373% 102.2899.88 99.36 98.35 99.511 97.1698.69 98.81 101.07 98.81 96.541 96.99 99.98)

.." "" .. """ 10 c10

,' Minisfry ofEnergy, Minesand Petmleun!Resomes

CHONDRITE-NORMALIZED REE Pl.OT PERRYRIVER INTRUSIVE CARBONAITES

Figure 48. Carbonatite plot, Mount Graceand Perry River area.

lIIIIIIiIIIIIIIiIIIII,,IIITrr Lo Ce Pr Nd Sm Eu Tb Dy Ho YbTm I. Rare-earthElements ~ ~~ ~~ ~ ~ ~~ ~ ~ ~~ ~~ ~. CHONDRITE-NORMALIZED REE PLOT CHONDRITE-NORMALIZED REE PLOT RENCARBONAllTES MOUNT GRACE INTRUSIVECAREONLTITES

103

i j 102

10 \ ri

I z La Ce Pr Nd Sm Eu Tb [ly Ho YbTm LI La Ce Pr Nd Srn Eu Tb Dy Ho Tnr Yb i Rare-earthElements Rare-earthElements Figure 49. Chondrite normalized rare earthplots, carbonatites, west flank, Frenchman Cap Dome. (A) Chondrite-normalized KEE plot - Perry River intrusive carbonatites;(B) Chondrite-normalized REE plot- Ren carbonatites; (C) Chondrite-normalized REE plot- Mount Grace extrusive carbonatites.

Buliefin 88 65 Brifish Columbia

The carbonatite is commonly internally banded, with characteristicofcarhonatiteselsewhere(e.g.,LeBas,1981). one or several layers of 'blocky' tephra interbedded with All the carbonatites show typical light rare-earth element finer grained, massive or laminated carhonatite (Plate 29). enrichment patterns on chondrite-normalizedplots (Figure The blocky tephralayers contain three types of matrix-sup- 49a, b, and c). Light rare-earth enrichment is not as marked ported clasts: small granular albitite clasts, commonly upto as that displayedby samples fromthe Aleyor Rock Canyon 3 centimetres in diameter, consisting of pure albite or albite Creek showings;however, total rare-earth values andslope with variable amounts of phlogopite; syenite clasts, gener- (measure of enrichment) aregreater than those for car'mna- ally 1 to 10 centimetres in diameter,consisting of potassium feldspar with variable amounts of plagioclase, calcite, apa- tites hosted byPrecambrian or Early Cambrian strata in the tite and rare feldspathoids; and larger rounded to sub- Omineca Belt. rounded biotite-plagioclase gneiss, schist and quartzite The Mount Gracecarbonatite has total rare-earth ele- clasts that are commonly up to 20 centimetres in diameter. ment concentrations ranging from approximately6oE1 ppm The lithic clasts may be internally folded and have a pro- to greater than So00 ppm (AppendixI), significantly h igher nounced layering or foliation that is randomly oriented with respect to the regional mineral foliation. The lithic and albitite clasts are generally randomly distributed throughout a tephra layer, hut in some layers they are concentratedin the centre or occasionally graded withclast size increasing up-section. Near the northern mapped limit of the carbonatite layer, where it is thickest, unusually large syenitic clasts, over 1 metre in diameter, occur within it.

GEOCHEMISTRY Carbonatites from the Perry River, Mount Grace and Ratchford Creek (Ren) areas display a large compositional range with respect to major and trace elements (Table 11; / Appendix 1). The majority of the Mount Grace extrusive and Perry River intrusive carhonatites are sovites while at the Ratchford Creek showing magnesio-carbonatites pre- dominate (Figure 48). All are highly enriched in strontium, barium, niobiumand rare-earth elements relative to carbon- Subalkaline ates of sedimentary origin (Table 11). These high valuesare rocks

rT 30.00 40.00 50.00 60.00 70. Si07

x overageintrusive syenite, Perry River area

Marble impuremarble, coic. schist 0- localitya Sample 30.00 40.00 50.00 60.00 70, Si09 Figure 50. Detailed sectionof the Mount Grace carbonatite,Blais Creek showing. La, Ce and Nd values of selected samples from Figure 51. Alkali-silica and agpaitic index plots, Peny River HBy (1988). syenites.

66 Geological Survey Branch Ministry of Energy, Mines and Petroleum Resources

b syenites MI. Grace corbonotite A k-feldspar-albito fenite / I ' I R& 'carbonatite albitefenite fenit* / \

Veniter amphibole

Figure 52. Major element ternary plots, Perry River and Mount Grace area alkaline rocks. (A) CaO-Na20-KZO plot, Pen) River and Mount Grace areas;(B) AFM diagram, Perry River syenites and fenites.

Figure 53. Fenite plots, Perry River area. (A) CaO-Na20-KZO-MgO+Fez03fenite plot, Perry River area; (B) NazO-KzO-Fez03 fenite plot, Perry River area. than sedimentary marbles;rare-earth element analyses can miaskitic varieties are present, but on average, the Perry be used to differentiate the layered Mount Gracecarbonatite River syenites are miaskitic in nature (Figure 5 1). Alkali and from its hostrocks (Figure 50). Thin tuff layers, with high iron-magnesium fenites occur in the Perry River area, and rare-earth element concentrations, are present within me- can be clearly differentiated on ternary plots (Figure 53). tasedimentary marbleat the top of the carbonatite unit (sam- The alkali fenites may be further subdivided intc, soda-rich ple H85P25B) and some of the fine-grained marble layers (albite) fenites and soda andpotash-rich (albite - potassium within the basal part of the carbonatite unit (those that have feldspar or 'syenitic') fenites; however, these two types low REE concentrations, e.&, H85F'26B, H85P261)may be are largely of sedimentary origin with only a minor tuff compo- compositionally gradational (Figure 53). Syenitic fenites nent (Hoy and Pell, 1986). This intimate interlayering of cannot be easily distinguished from igneous syenites on carbonatite and sedimentary marblesupports argument for AFM or Naz0-Kz0-Ca0 ternary plots (Figure 52). Albite an extrusive origin for the Mount Gracecarbonatite. fenites are most common as clasts in the Mount (Gracecar- Intrusive syenites are quite varied in major element bonatite and Hoy (1988) suggests that this mayindicate that composition (Table 1; Figures 51 and 52); both agpaitic and sodium fenitization is more importantat depth adjacent to

Bulletin 88 67 the parent magmas, andthe more potassic and iron-magne- which it is intruded by). A Lower Cambrianlead-lead date sinm fenitization occurs at higher structural levels. obtained from galenain the stratiform Cottonbelt lead-zinc deposit higher in the succession (H6y and Godwin, 1988) GEOCHRONOLOGY supports the interpretation that the age of the mafitling Uranium-lead analyses of zircons from the Mount gneiss succession spans Late Proterozoicto early Pa1a)zoic Grace carbonatite produce nearly concordant agesof 70 to time (Hoy, 1988). The Mount Gracecarbonatite also must 100 Ma (R.R. Parrish, personal communication, 1987) be LateProterozoic to early Paleozoic in age.It occurs high which indicates that the zircons are mainly metamorphic in in the mantling gneiss stratigraphy, only 110 metres below origin. Uranium-lead systematics on pyrochlore from the the Cottonbelt deposit; and based on this, it is reasonable to Mount Gracecarbonatite yield a 60 Ma date, which is also assume that it is close in age to the Cottonbelt deposit, ]?rob- ably latest Hadrynian to Eocambrian (circa 570 Ma). Addi- indicative of metamorphism. tional work on uranium-lead systematics is currenlly in Because absolute dating methods have notbeen effec- progress in an attemptto verify these conclusions. tive in establishing the age of Mount Grace and Perry River carbouatites, other methods must be attempted. The Mount THREE VALLEY GAP (82L/16) Grace and Perry River carbonatites are hosted in the mantling gneisses of the Frenchman Capdome, a rock sequence Carbonatites and leucosyenites are found alongthe Vic- that also contains the Mount Copelandsyenite gneiss (un- tor Lake Main logging road(latitude 50°55'34"N, longitude derlying the carhonatites) and the Cottonbelt stratiform lead-zinc layer (overlying the carbonatites). The Mount TABLE 12 Grace carbonatite, which is extrusive, must be the same age CHEMICAL ANALYSES, THREE VALLEY GAP as the sediments with whichit is interbedded. ALKALINE ROCKS The date of approximately 770 Ma, obtained fromzir- cons in the Mount Copelandsyenite gneiss (Oknlitch et al., wi % 1 2345 1981) whichintrudes the basal part of the succession in the Si02 18.7021.60 33.40 46.50 50.96 Ti02 0.680.670.81 0.72 0.64 0.42 Jordan River area, suggests that the basal part of the succes- A12036.298.2911.02 13.80 21.26 17.62 sion is Late Proterozoic (it mustbe at least as old as rocks Fe203T8.168.7 6.208.33 2.704.34

MnO 0.26 0.23 0.16 0.21 0.08 0.07 IMeO 2.70 2.42 2.44 2.15 1.85 0.891 Cab 33.20 29.80 21.95 18.90 11.29 5.17 Na20 0.92 1.60 1.93 2.18 3.35 3.64 K20 2.85 3.26 3.59 2.40 2.37 6.76 LO1 22.25 20.75 14.63 2.26 1.29 P205 3.21 3.20 2.10 2.40 2.27 Tofal 99.80 100.1 98.09 99.81 99.7 ppm Ni <2 <2 1 30 1 Cr 3 3 <20 63 <20 e20 14 13 15 12 20 12 co 15 13 14 28 %St 131317301418327931353433 Ba 1643826 836 2405 1726 1568 Zr 207 296 79 21731 177 Nb 429 114 110 9692 33 Y 51 47 37 3424 42 La 212 55 206 60 131 148 Ce 140275 256 396 401 154! .1Nd 140 151 - 111 ' yb 4.2 4.4 - 2.8 sc 24 29 20 Ta 82 1 <2 19 1 21 'Th 0 10 6<6 4 4 1. - 3VG136A - biotite sovite; 2. - 3VG135A - sovile; 3. - 3VG139A - biotite sovite 4. - 3VG137 - border zonebehveen carbonatite and associated syeniiic rocks; 5. - 3VG137B - syenificfenite, confabzone; 6. - 3VG139B -pegmaiiiic sphene-rich syenite. Major elements analysed byICAP, alkalinefusion, in samples 1,2,4:All irace elemenis analysed by XRF except REE in 1,2, & 4 which Plate 30. Large feldspar clots in biotite-rich carbonatite, Three Valley Gap area. were analysedby INAA.

68 Geological Survey 1:ranch Minisfyof Energy, Mines and Petroleum Resources

Figure 54. CaO-MgO-FQOjt+MnO carhonatite plot,Three Valley Gap.

1 Lo Ce Pr Nd Sm Eu Tb Dy Ho Tm Yb LI Rare-earthElements ___ Figure 56. Chondrite-normalized REE plot - Three Valley Gap. 118"23'29"W) which joinsthe TransCanada Highwayfrom the south, approximately 3 kilometres east of Three Valley Gap. Outcrop is limited to roadcuts, at elevations between 900 and 1500metres. The road is in good condi:ion, passable by conventional vehicles. The carbonatites and syenites occur as thin, discontinuous bedding-parallel lenses in pelitic metasedimentary rocks. Both the intrusions and hostrocks have been metamorphosed to upper amphibolite facies (sillimanite zone) and the pelites have been extensively migmatized. Thehost- rocks are of uncertain affiliation, they crop out near the mapped boundary (Joumeay and Brown, 1986) between Hadrynian Horsethief Creek Group strat;r and the autochthonous 'mantling gneiss' succession of I'renchman Cap dome. Tentatively they are assigned to tht: mantling gneisses. Carhonatite lenses are generally 20 to 63 centimetres in width and have envelopesof mafic feniter, 10 to 30 centimetres thick, developed between them and adjacent rocks. Everywhere observed, thefenites in are dirxt contact with, and gradational to, syenites. Commonly th- carbona- tite occurs as lenses within the fenite. CARBONATITES, FENITES, SYENITES The carbonatites are buff to brown-weathering rocks that are primarily composed of calcite (45-50%), biotite (5-20%). apatite (5-15%), perthite (up to lo%), hornblende (5-30%),augite(1-10%)andtracesofsphene.In]~lacesthey contain feldspathic lenses or augen (Plate 30). sirnilar inap- Figure 55. Major element ternary plots,Three Valley Gap. pearance to migmatitic leucosomes. Hornblende andaugite

Bullefin 88 69 are more abundantat the marginsof the carbonatite lenses: veloped within them than is typical and hence have high biotite is the dominant maficsilicate mineral in the centre. Si02 (Table 12). They are also relatively enriched in iron All carbonatites display a well-defined biotite-amphibole and plot within the ferrocarbonatite field on a Ca0-Ivlg0- foliation. Fez03+MnO ternary plot (Figure 54). Samples collectcd ad- Fenites are green on weatheredand fresh surfaces and jacent to the carbonatites have major elelnent generally containabnndant augite, hornblende, calcite(25% concentrations intermediate between the carbonatites and or less), scapolite and plagioclase. Accessory mineralsin- the ‘syenitic’rocks (Figure 55). Rare-earth elementcontents clude biotite, apatite, sphene andnepheline. Potassiumfeld- are low, relative to Perry River, Ren and MountGrac: car- spar, perthite, allanite, zircon and garnet (coarse grained, bonatites (Appendix 1) and slopes on chondrite-nomillized brown body-colour) mayalso be present. rare-earth plots (Figure 56) are flatter than for carbonatites The leucosyenites are massive, white, medium to on the west flank of the Frenchman Cap dome (less light rare-earth enrichment). coarse-grained rocks that generally contain potassium feld- sparzplagioclasehugite+sphene.Their origin is unclear; unambiguous field relationships are not exposed. These GEOCHRONOLOGY syenites may actually be syenitic fenites, rather than intrn- sive phases. Uranium-lead analyses of zircons separated from the Three Valley Gap carbonatite produce nearly conccrdant GEOCHEMISTRY ages of 70 to 100 Ma, as was the case withthe Mount Grace The carbonatites at Three Valley Gap are calcitic (high carbonatite, indicating that the zircons are mainly metamor- Ca0:MgO ratio), but tendto have moresilicate phases de- phic in origin.

70 Geologicul Survey Binnch ULTRABASIC DIATREMES IN NORTHERN

BRITISH COLUMBLQ"

Only twobreccia pipes have so far been recognized in pearance of a stretched-pebble conglomerate. Thenorthern British Columbia northof Prince George(Figure 2); the Os- and central parts of the diatreme havebeen cut by fluorite- pika pipe nearthe Peace Reach,east of Williston Lake and calcite and fluorite-calcite-pyrite stockwork veins contain- a small diatreme in the Kecbika Riverarea of the Cassiar ing minor amounts of galena and molybdenite. Similar Mountains, westof the Rocky Mountain Trench. Both are breccias (minus thephlogopite) arepresentin the EdRiver hosted by middle Paleozoic carbonate rocksand are associ- -White River area of the southern Rocky Mountains (Yell, ated with carbonatite/alkaline rock complexes. The dia- 1987). treme in the Kechika River area is the only onedocumented west of the Rocky Mountain Trench. Associated dikes are quite common periphcal to the main diatreme and onthe ridges to the north (Figures 21 and THE KECHIKA RIVER DIATREME AND 22). They crosscut both the carbonate hostrock!; and the RELATED ROCKS (94L/12,13) mottled phyllites. The dikes, in general, are extremely well foliated and average 1 to 2 metres in thickness. They are A suite of alkaline igneous r9ks in the Kechika Ranges similar in composition and appearanceto the matrix of the of the Cassiar Mountains is intermittently exposed in a main diatreme, comprised predominantlyof iron and mag- northwest-trending zonein excess of 20 kilometres long, the centre of which is approximately latitnde 58"42'north and TABLE 13 longitude 127"3O'west.Tracbytes,syenites,malignites,car- GEOCHEMISTRY OF SELECTED DIATREME bonatites and related tuffs and agglomeratesare present in BRECCIAS AND RELATED DIKESAND TI JFFS , thissuite(seeChapter2);adiatremebrecciapipeandrelated KECHIKA AREA " dikes and tuffs are also exposed in this area. The igneous - ~~~~~~ ~. rocks are hosted by middle Paleozoic(Silurian?) carbonate Diatreme breccia strata and have been deformed and metamorphosed to 13.3434.35 35.68 37.04 36.75 19.82 41.46 greenschist facies. 0.851.141.18 1.12 0.740.810.95 A complex diatreme containing a numbes of breccia A1203 6.076.3210.35 10.42 10.07 5.35 9.78 9.48 5.96 7.13 6.92 7.4: 6.81 phases, related tuffs and breccia dikes crops out near the centre of the belt of alkaline igneous rocks(Figures 21 and 0.14 0.12 0.38 0.39 0.48 0.41. 0.26 3.65 15.11 8.45 10.68 10.01 9.3;' 5.1.1 22). These rocks weather greenishsilver to rusty orange and 9.55 5.44 12.55 9.89 11.27 20.21 11.7 are weakly to extremely well foliated. The main diatreme is 0.06 2.13 2.10 2.74 2.96 0.2:; 0.72 exposed in acreek at approximately 1560 metres elevation; 4.80 1.71 7.74 6.04 4.20 4.0:: 3.76 dikes and tuffs are present on the slopes and ridges to the 16.8723.31 14.79 13.05 14.22 28.4:' 15.88 11 north and west of the diatreme, at elevations of up to 2230 L0.24 0.19 0.26 0.21 1.3:218 metres. Exposure in the area is moderate to excellent; buck- 6.68 99.3099.11 98.71 98.04 97.51; 95.49 brush andscattered trees are present in the valley bottoms, while the upperslopes are barren. Access to the area by 689270 210 514 600 711 1G2 is 1100 1108 510 720 - 32r1 641 helicopter from Watson Lake, Yukon or Dease Lake, B.C., - 82 - 269 21 56 150 and 160 kilometres distant, respectively. 390 95314 320 230 105 127 295 212 790 610 708 8912 420 LITHOLOGY Ba 970 179 500 430 412 41'1 174 Zr 105 106 225 440 181 56 175 The main diatreme (Figure 22) comprisesvery inhomo- Nb 9 60 20 <5 92 43,3 80 geneous, heterolithic tuffisitic breccias with roundedto an- 32 23 32 55 50 3885 46 gular xenoliths up to 7 centimetres in diameter. Quartzite 34131'7 19915 360 440 26 and carbonate rock fragments dominatethe xenolith popu- 33 35423270 440 560 510 lation; some autoliths, rare syenite fragments and some Nd - 47 204 201- 75 black argillite clasts were also noted. Quartz xenocrysts,

Bulletin 88 71 Brifish Columbia nesium-rich carbonate minerals, feldspars, muscovite and serpentine. Some quartz and apatite may also be present. The dikes locally contain chrome spinels, small lithic fragments and fragments of devitrified glass. Some contain chrome-green (chrome mica)or dark green(chlorite and biotite) elliptical patches which probably represent sheared and altered fragments or crystals. One dark green weathering dike contains abundant smallrock fragments andaltered olivine macrocrysts. Tuffs outcrop onridges near the centre of the property, immediatelynorth of the main diatreme andat the north end of the property, south of Boreal Lake (Figures 21 and 22). These pyroclastic rocks are rusty orange to silver-green weathering with a pale green fresh surfaces, very similar in appearance to some of the dikes. They are conformablewith the host carbonate succession and are interbedded with brown, blocky weathering agglomerates and aplitic trachytes. Chrome spinels are present locally. In thin section, these rocks are seen to contain plagioclase laths, siderite spots and altered, six-sided crystals (clinopyroxenes) in a fine-grained matrix of carbonate, sericite or

~~IC,feldspar ~~~~ and~ oiaqnes. ~~ ~~~ ~~ ~ These rocksmay be the extrusi!~- @ 0 didreme X dike + tuff~~

~~ultramafic~~

~~Figure 58. Major element ternary plots, Kechika diatrelre and 0.00 5.00 15.0010.00 20.00 25.00 related rocks.~~

~~0 0 Kechikodialreme 25.00 1500.00 and dikes * Kechikatuffs 0 diatreme 20.00 X dike 4 + tuff~~

~~V 15.00~~

~~baranifiie tephriie alkollne larnprophyre 5.00~~

0.00 m 20.00 30.0020.00 40.00 50.00 60.00 70.00 SI07 Cr Darn L gure57.Majorelementdiscriminantplots,Kechikadiafremear Figure 59. "Average" compositionsfrom Wederhi.1and lated dikes and tuffs. Maramatsu, 1979.Nivs Crplot, Kechikadiatreme, dikes an(ituffs.

~~72 Geological Survey llranch Minisrry of Energy, Mines and Petmleun: Resources "~~

Based on modal mineralogy (olivine, clinopyroxene, plagioclase and/or potassium feldspar and minor phlogopite) it is difficult to classify these rock they showsome CHONDRITE-NORMA1 17Fn REE PLOT similarities to alkaline basalts (basanites). RELATED GEOCHEMISTRY Major element analyses of samples fromth,: Kechika 0 diatreme diatreme andrelated dikes and tuffs (Table 13)in(licate that X dike these rocks are relatively low in silica and aluniinum and + tuff moderately enrichedin calcium andmagnesium. On a K20- MgO discriminant plot samples fromthe Kechikt pipe and related rocks fall predominantly within or near the leucitite field (Figure 57a), while on an alkali-silica discriminant plot they fall between the alkaline lamprophyre andalnoite .field (Figure 57b). On the ternary Fe-Al-Mg plot, samples fall within the melilitite (alkaline lamprophyre) field (Figure 58a). On an AFM plot,samples plot closer to the: base (the A-M side) than alnoites or typical basalts (Fignrt: 58b); the diatreme samples are similar, in this respect, to samples of other rock types in the Kechika area (see Figure 24b). Based on major elementchemistry, it is difficult to c1ar:sify these rocks although they do show some chemicalaffinity to alkaline lamprophyres (nephelinites) or leucitites. Alteration may have affected major element chemistry enor.ghto pre- clude definitive classification. Diatreme anddike samples show afair rangc: of nickel and chromevalues; some are moderatelyenriched, contain- 1 ing up to 0.11% chrome and 0.07% nickel. Tht:y contain Lo Ce Pr Nd Srn Eu Tb Dy Ho Trn Yb Li higher concentrations of these two elementsthan do there- Rare-earthElements latedtuffs,inwhichtheigneouscomponenthasbeendiluted (Figure 59). Diatreme and dike samplesare also moderately Figure 60. Chondrite-normalized REE plot - KecW diatremes enriched in fluorine, containing between0.18 and 1.9% (Ta- and related dikes and tuffs. ble 13). Theycontain low to moderate amountsof ::areearths

~~~~ Plate 31. Dolostone clastwith reaction rim, Ospika pipe.~~

~- Bulletin 88 73 (up to 510 ppm La) and, on chondrite-normalizedrare-earth OSPIKA PIPE (94B/5) plots, generally display shallow, negatively sloping curves The Ospika pipe is a small diatreme located on (Figure 60) which are indicative of a lowto moderate degree Cominco's Aley claims (latitude 56"27'N, longitude of light rare-earth enrichment. The diatreme and related 123"45W) approximately 140kilometres north-nortttwest rocks are anomalously enrichedin rubidium and havevery of Mackenzie, on the east side of Williston Lake bemeen the Peace Reach and OspikaRiver. Access to the area is by low total strontium:rubidium ratios that average around 2: 1 helicopter from Mackenzie. (Table 13). The diatreme crops outon forested slopes at approximately 1550 metres elevation (Figure 3). It is only 2, few GEOCHRONOLOGY hundred metres from the large Aley carbnatite coniplex (see Chapter 2), but the relationships between the carlmna- No radiometric dating has been done onalkaline rocks tite and the diatreme are unclear. from the Kechika area. Field relationships suggest that they are similar in age to the host strata, Silurian or slightly LITHOLOGY younger. The Ospika pipe is a composite diatreme(roughly 20 by 50 metres inarea) containing at least five distinct brxcia TABLE 14 and massive phases andintruding Ordovician carbonms of CHEMICAL ANALYSIS - OSPIKAPIPE the Skoki Formation.It is massive to foliated and red-brown ~ ~ ~ ~~~ weatheringinoutcrop,withfluoritepresentnearthemargins 1 2 3457 6 27.9024.18 32.09 30.59 26.66 28.65 0.99 Ti02 2.76 2.15 2.76 1.67 2.25 2.58 0.38 Ai203 5.43 4.77 6.25 5.01 5.19 5.61 0.25 Fe203T 9.47 7.94 9.25 9.56 7.61 8.67 5.21 0.20 0.19 0.17 0.22 0.16 0.17 0.55 12.72 10.04 14.65 10.62 12.47 14.07 14.69 15.63 17.26 13.40 17.20 17.52 14.84 27.53 0.01 1.23 0.95 2.29 1.55 1.85 0.00 1.43 4.01 5.55 3.80 4.01 4.02 0.12 10.00- 11.51 24.79 10.83 14.32 18.07 17.0541.59 1.12 0.84 0.09 1.80 0.99 0.08 0.28 0.12 0.16 0.01 0.80 0.41 I %.25 97.67 96.93 97.25 97.50 99.2691.81 0.95; 0.95; 5.00- 230 190 360 220 290 330 40 455 331 481 185 409 387 232 co 48 24 46 39 40 47 10 Rb 48 42 160 115 148 118 <8 Sr I 514 1257 1134 1650 1448 837 1601 0.00 Ba 788 1163 1248 1741 1737 1290 20138 Zr 300 53 263 682 261 303 4 Nb 241 625 180 245 147 168 226 Y 36 72 32 51 26 26 34 La 183 177 124 170 96 199 3858 25.00 Ce 322 332 217 369 85 166 6298 Nd -; Yb <-2 2 <-4 0 <-7 <-1 6 20.00 sc 33.2 29 32.1 29 32.6 28.831.5 Ta 13 15 10 16 6 a 16 Th 90 36 21 40 16 173117 ' 15.00 +phonolite u 16 13 16 19 5 16 8 V 317 398 353 261 342 253320 4 from Alno cu 109 74 119 __73 __ 103 ___ 112 80 10.00 frachybaaalf

~~5.00 barall +andesite I' klrnberlife~~

~~0.00 rn 902~~

~~Figure 61. Major element discriminantplots, Ospika pipe.~~

~~74 Geological Survey Branch Ministry of Energy, Mines and Petroleum llesoumes~~

on the pipe. The phases are differentiated by size and per- Phlogopite dominates the macrocryst assemblages, centage of fragments of sedimentay rock, macrocrysts and comprising 5 to 20% of the rock, with titaniferous augite, pelletal lapilli. Contacts between phases may be sharp or rare altered olivine and bright green diopside also present gradational. Locally, narrow dolomitic dikes crosscut dia- locally. Phlogopites range froma few millimetres to 3 centimetres in size, augites from a few millimetres tc. 2 centi- treme breccias. metres. The phlogopites are orange in colour and have The breccias contain 2 to 25% subangnlar to snb- normal pleochroism. In some samples, they have thin, rounded fragments of sedimentary rock. These range from bleached rims; in others, the rims are darker than the core a fewmillimetres to 50 centimetres across, with most inthe of the grains. 2 to IO-centimetre range. Larger fragments are dolomitic The matrix to most phases is fine grained and light with prominent reaction rims (Plate 31). Rare cognatexeno- green-grey in colour.It is a godigneous or magmatic ma- liths are present, but no exotic xenoliths were found. One trix, consisting of fine-grained dolomite and felled plrlo- distinct phase is composed of abundant small pelletal lapilli gopite, chlorite, amphibole with or without talc. It contains abundant fine-grained opaque oxides and, in some places, (50-60%).macrocryptic phlogopite(5-10%) and small frag- pyrite. ments of sedimentary rock(less than 10%) in a fine to me- Clast andmacrocryst-rich brecciadikes, 50centimetres dium-grained carbonate matrix. wide, crop out onridges 0.5 to 1 kilometre away fromthe main breccia pipe. These dikes do not appearto be continuous with the diatreme at surface, but have verysimilar clast and macrocrystpopulations. Locally, the matrixof thedikes is considerably morecalcareous than that of the diatreme. Both the dikes and mainpipe havesuffered some (degreeof alteration. Bluepleochroic sodium amphiboleisukdquitous, often rimming other phases. The Ospika pipe andrelated dikes may be classified, on the basis of petrography, as ultramafic lamprophyres using the criteria given byRock (1986)and, more speci:ically, as aillikites. These arerelatively common ultramafic lamprophyres that are often associated with carbonatites. They are similar to alnoites, but lack goodevidence of meltlite. GEOCHEMISTRY Major element analyses of samples from the Ospika pipe and related dike rocks (Table 14) indicate that the pipe is low in silica and high in calcium, magnesium andiron. On a KzO-MgO discriminant diagram (Figure61a:r analyses group in anarea which is overlappedby the leucitii e, olivine melilitite and alkaline lamprophyre fields. It should be noted, however,that on this diagram, alnoites from Alno fall

~~ ~ ~~~~~~~~ ~ __~ ~~

~~0 Ospika pipe 1500.00~~

~~Average basalt Average kirnbtrliles~~

0.00 1000.00500.00 1500.00 Cr ppm _- Figure 62. Major element ternary plots, Ospika pipe Figure 63. Ni-Cr plot, Ospikapipe. ~ ~ ~~ ~~~~~~ within the alkaline lamprophyre field, which suggests that The geochemical data do not conflict with thc pet- the ultramafic lamprophyre field should be extended; this rographic classification of the pipe as an ailliki:e, or plot is not strictly adhered to in attempting a chemicalclas- melilite-free variety of alnoite, which, according to Rock sification. Analyses from the Ospika pipe plot relatively (1986) is a member of the ultramafic lamprophyre family. close to the type alnoite. The sameis true on an alkali-silica plot (Figure 61b). Ternary AFM and MgO-AIz03-Fe~03 plots (Figure 62) show that analyses from the Ospika pipe GEOCHRONOLOGY plot in or near the alonite and/or aillikite (a melilite-free Rubidium-strontium isotopic studies on mica sep,uates alnoite) fields. from the Ospika pipe give an ageof 334f7 Ma. Potas-’,111111- The Ospika pipe has a restricted range of nickel and argon studies on the same sample yielded323f10 Ma (Ap- chrome values andcontains relatively low concentrations of these elements, similar to the ‘average’ nephelinite (Figure pendix 2). These data suggest that the pipeis very similar in 63). It is somewhat enrichedin titanium, barium,strontium age to the Aley carbonatite complex, which it flanks. The and niobium, and has fairlya restricted range of total stron- temporal and spatial association between carbonatites and tiummbidinm ratios, averaging around 13:l (Table 14). alnoites or aillikites is well documented (Rock,1986:..

~~76 Geologicul Survey Bmch Minisiry of Energy, Mines and Peiroleum Resourres "~~

~~ULTRABASIC DIATREMES IN THlE GOLDEN - COLUMBIA ICEFIELDS AR:EA~~

Numerous diatremes are located along the Alberta - suggests that these rocks are neither kimberlites nor lam- British Columbia border @2N, 83C) between 50 and 90 proites, the twolithologies currently known to contain eco- kilometres north of Golden (Figures 2 and 64). The terrain nomic concentrations of diamonds. in the area is rugged and the diatremes outcropat elevations of 2200 to 3000 metres. In all cases access is by helicopter. BUSH RIVER AREA (LARRY CLAIMS) Most of the diatremes are hosted by Upper Cambrian car- (83CP) bonate rocksand, in most cases, consanguineous dikes are Near the headwaters of the Bush River :latitude also present. 52"04'20"N, longitude 117'23'50'W Figure 64) ,I suite of Microdiamonds have reportedly been recovered from dikes and small diatremesintrudes Upper Cambrianstrata. heavy mineralseparates taken fromtwo of the pipes in this Three diatremes were examinedin this study (Figure 63, swarm (Northcote, 1983a. b; Dummett et al., 1985; George revealing two breccia types. The breccias appear ,quite dif- CrossNewsLetter,Jan.23,1990).Preliminaryinvestigation ferent in the field, but the division is somewhat arbitrary.

A Bush Riverpipes and dikes B LensMountain pipe C MonsCreek area LEGEND D ValenciennesRiver area Foliatedbreccia phose with pelletal lapilli pipe E HP Rusty weathering quartz xenocrystic bre:cia Fine grained massivedike phose Figure 64. General geology and diatreme locationsin the Golden Mocrocryrt richdikes (micas, pyroxenes, etc.) - Columbia Icefields area. indicates diatremes or dike swarms. Macrocryst rich dikes withbreccia core:$ GeologymodifiedfromWheeler(1962)andPrice(1967a,1967b). _- For legend see Figure 73. Figure 65. Diatreme breccias and dikes, Bush River ma(83CL3).

~~Bulletin 88 77 Plate 32. Rusty weathering, clast-supported megabreccia, Bush Riveraea.~~

~~78 Geological Survey Branch ~ . ~ , .~ _r:: ~...... 'l -. ... ~ ~ ~ .".~~

~~Minisrry of Energy, Mines and PefmleumResources~~

Plate 34. Limestone-cored armoured xenolith in diatreme breccia, Bush River area. Plate 36. Boulder from adike, Bush River area. Dike has a brcccia core containing abundant fragments of sedimentary ~.ockand a finer grained, macrocryst rich rim.

~~Plate 35. Altered micamacrocryst in diabeme breccia, Bush River Plate 37. Laminated (flow-banded) marginof a fine-grained dike, area. Bush River area.~~

Bulletin 88 79 The pipes are massive; onlythe southeastern diatreme has a margin that is foliated, with the foliation subparallel to the contacts (Pell, 1987; Ijewliw andSchulze, 1989). The northeastern pipe comprisesrusty orange weathering, clast-dominated megabreccia(Plate 32). The clastmatrix ratio is approximately 39. Over 99% of the clasts are subrounded to subangular fragmentsof the hosting carbonate lithologies, ranging in size from 1 to 75 centimetres, with an average size of 10 to 40 centimetres. Altered granitoids and, less commonly, gabbroic rocks make theup balance of the xenolith population. The matrix is predominantly carbonate and quartz-sandgrains. The second typeof breccia, exhibited by the central and southern pipes, is also clast dominated andgenerally massive, but is rusty to dark green weathering(Plate 33) rather than orange in colour. The clastmatrixratio is greater than in the first breccia type andthe clast population morevaried. Approximately 50% of the clasts are subangular fragments of sedimentary rock, carbonates, shales and some ortho- quartzites. Two to five percent of the xenoliths consist of granitic material; these fragments may be either rounded or angular and are in the 5 to 15-centimetre size range. Rounded, 8 to 25-centitnetre fragments of altered igneous- looking material comprise 10 to 20% of the xenoliths.These Plate 39. Fragments of sedimentary rocks in a buff-weathering, clasts consist of coarse, randomly oriented carbonate grains, quartz xenocryst-rich breccia, Mons Creek area.

Plate 40. Photomicrograph of quartzxenocryst-rich bn:ccia, Plate 38. Photomicrograph of an altered pyroxene crystai in a similar to that shown in previous photograph. Quartz xenwrysts matrix containing abundant altered mica; dike, Bush River area. are enclosed in a matrix of carbonate, chlorite and iron-o:ddes. Long dimensionof photograph is2.5 mm. Long dimension of photograph is 2.5 mm.

~~80 Geological Survey Branch Ministry of Energs Minesand Petroleum Resources~~

Figure 66. Sketch showing distributionof diatreme related rockson the lack claims Lens Mountain area; sketch drawn from photog,raph taken by C. Fipke. View is of the ridge southeast of Lens Mountain, facing northeast. chrome mica and opaqueoxides. Spectrographic analyses surfaces are generally a dull greenish grey colour. Theyhave indicate high silica content; these clasts are possibly altered coarse xenolith andlor macrocryst-rich cores and finer syenites. Many of the rounded xenoliths are armoured, or grained margins (Plate 36). Contacts withiuthe (dikes may mantled bya rimof fine-grained mica-rich igneousmaterial be gradational or distinct and often the margins have a similar to the breccia matrix. An additional 5 to 10% of the strongly flow-banded texture (Plate 37). In thin swtion, the breccia fragments arecognate xenoliths. The remainderof dikes are porphyrytic withaltered macrocrysts, phenoclysts the clast population is made upof spherical structure (also and glomerocrystsof olivine, pyroxene (Plate 33) and bi- referred to as accretionary lapilli or globular segregations) otite. The olivine crystals, some of which contain inclusions ranging from a fewmillimetres to 3 centimetres in size and of red-brown spinel, are altered to calcite, serptmtine and frequently cored by small fine-grained limestone fragments talc. The groundmassconsists of a networkof alteredbiotite (Plate 34). Armoured xenoliths and accretionary lapilli are with dusty secondaq calcite, minor serpentine, soinels and features common to pyroclastic rocks (Fisher and opaques (Ijewliw and Schulze, 1989). Schmincke, 1984). Silvery, altered mica macrocrysts, upto Based on modalmineralogy, including the pseudomor- 3 centimetres in diameter, are abundant (Plate 35); they phed phases (olivine, pyroxene, biotite, plagiodase). the were, most likely, originally biotites. The matrixof the brec- dikes and diatremesin the Bush Riverarea can beclassified cia consists of chlorite>calcitequartz>trace apatite. In thin as lamprophyres of either alkaline or calcalka1ir.e affinity. section, it is seen to comprise 25% euhedral to suhhedral The best designation appears to be as olivine-kzrsantites, olivine crystals that have been pseudomorphedby either ser- which are part of the calcalkaline lamprophyre family pentine, or calcite and quartz with magnetite rims, cloudy, (Ijewliw and Schulze, 1989)or biotite-camptonites, which brown plagioclase, biotite, euhedral calcite and trace are alkaline lamprophyres. amounts of magnetite and apatite phenocrysts in a fine- grained aggregate of dusty carbonate, quartz, serpentine, LENS MOUNTAIN AND MONSCRJ3EK magnetite, chlorite, felsic microlites and unidentifiable ma- AREAS (JACK AND MIKE CLAIMS) terial (Ijewliw and Schulze, 1989). (82N/14,15) Numerous subparallel dikes are present in the Bush River area, some of which crosscut the diatreme breccias; At both Lens Mountain(latitude 5 l”54’30”N. longitude they range in lengthfrom 50 to 600 metres andin width from 117°07‘30”W) and Mons Creek(latitude 51”49’:;O”N, lon- 0.5 to 2.5 metres. Bifurcation and remerging occurs along gitude 117°00’30”W; Figure 64) the dominant intrusive li- the length of some dikes and narrow,fine-grained apophyses thology consists of a buff-weathering, weakly foliated are common. Both homogeneous and zoneddikes are seen breccia with a low clastmatrix ratio (approximalely 1:3 or (Figure 65). The homogeneous dikes are fine grained and 1:4). The ‘Jackdiamond‘(Northcote,1983b) was recovered medium to dark green in colour. They may contain up to from this lithology and twoadditional microdiamonds have 10% small, silvery, mica phenocrysts andminor amounts of recently been recovered fromdrill core (George C ross News spinel or other opaque oxides. A dike with unaltered phlo- Letter, Jan.23,1990, p. 2).Clasts are smallsubaugnlarfi‘ag- gopite megacrysts was observedin one locality.The zoned ments of sedimentary rock, predominantly carbpnates, in dikes are rusty to dull green on weatheredsurfaces and fresh the 2-millimetre to 2-centimetre size range (Plate 39). The

~~__ Buliefin 88 81 British Columbia~~

'matrix' is pale green to buff incolour andconsists ofabun- dark red and havedark greyfresh surfaces. They consist of dant rounded quartz grains (xenocrysts), carbonate, chlorite subangular clasts of limestone and relict phenocrysts in a and iron oxides (Plate 40). Relict lapilli, with a preferred carbonate matrix. The matrix consists of 15% phenocrysts orientation, have also been observed(Ijewliw and Schulze, that are entirely pseudomorphed by fine-grained quartz 1989). At Mons Creek,this breccia grades into a clast-poor andor calcite. Some of the phenocrysts retain traces of sim- (5 to 10% clasts) green breccia with a foliated matrix con- ple twinning, with a morphology suggestive of sana4line. taining carbonate, chlorite and talc(?) or serpentine. In both Altered crystals of titanamphibole or sphene are also pre- areas, the enclosing sedimentarystrata are steeply dipping; sent; they have been replacedby calcite but retain a rimof the breccias, however, display a weakly developed subhori- inclusions of very fine grained sphene.The groundmrss is zontal to shallow-dipping planarfabric. At Lens Mountain, extremely fined grained and contains calcite patches a shallow-dipping layer of boulder breccia is enclosed in the (Ijewliw and Schulze,1989). sandy breccias. At Mons Creek, asmall, light green, strongly foliated, It has been proposed (C.E. Fipke, personal communi- tine-grained breccia crops outto the north of the main sandy cation, 1987) that these breccias are crater-infill material. diatreme. It contains fragments of sedimentary rock less Alternatively, they may be intrusive, formed through than 1 centimetre across and opaque oxidesin a matrix con- fluidizing of sediments by introdnction of volatiles explo- sisting of dolomite>quartz2pyrophyllite~inorchlorite, sively exsolved fromrising and vesicnlating magmas. The calcite, muscovite and trace apatite. In thin section, lhese subhorizontal fabric locally displayed in the breccias would rocks have a porphyrytictexture, but arehighly altered. Cal- have originally been steeply dipping (prior to deformation), cite replaces some phenocrysts, which may have been oli- which would favour the latter hypothesis. vine, manyof which have red-brownspinel inclusions. The original composition of other psendomorphed phenocrysts At Lens Mountain,two additional small breccia pipes is undeterminable (Ijewliw and Schulze, 1989). or dikes and light green, clast-free aphanitic rock are also present (Figure 66).The breccias are very coarse, weather At Mons Creek, onesmall, altered dike cutting the main diatreme and a second parallel dike outside the diatreme

~~~~. ~~~

LEGEND @Green foliatedbreccia phase @Quartz xenocrystic breccia aMassive diatremephase aFine-grained dikes Dikes with pyroxeneand olivine mocrocrvrtr Dikes with mica rnocrocrysts pyroxeneand olivine /LI Host limestone Plate 41. Serpentinizedolivine macrocrysts in a fine-grained, Figure 67. Diatreme breccias and dikes, ValenciennesRiver. massive diatreme phase, Valenciennes River area.

82 Geological 6'ranch Survey Ministry of Eneqy, Mines and Perroleunr Resources were observed. Oneunaltered porphyrytic dike and abundant unaltered float of porphyrytic dike-rock are present elsewhere onthe property. The altered dikes contain quartz aggregates replacing a lath-shaped, twinned mineral that may have been feldspar, some minute plagioclase grains (An25) that are partly replaced by calcite, and a phyllosili- cate mineral, partially replaced by calcite, with sphene inclusions and rims in a fine-grained groundmass of carbonate, chlorite and minorquartz and pyrite (Ijewliw and Schulze, 1989). The unaltered dike material contains 5% primary phenocrystic clinopyroxene, commonly augite or diopsidic augite with pinkish brown titaniferrous rims. Some grains also have titanium-rich cores, and an iuterme- diate, nonpleochroic zone. Other phenocrysts present include biotite, some amphiboles and olivine, completely pseudomorphed by calcite or chlorite, with red-brown spinel inclusions. The matrixcontains microphenocrystsof clinopyroxene, biotite, sphene and plagioclase (Anzs) in a groundmass of carbonate, chlorite, interstitial quartz, fine- grained serpentine and opaqueoxides. The main diatremes in the Lens Mountain and Mons Creek areas have only minor igneous components due to intense sedimentary rock contamination andare difficult to classify. The dikes at Mons Creek, however, have a preserved mineralogy (titanaugite, plagioclase, biotite, ampbi- bole, olivine) which allows classification as alkaline Plate 42. Fine-grained boudinageddike subparallel to tedding in lamprophyres, or more specifically, biotite camptonites buff-coloured carbonates. Diatreme breccia in the right (Ijewliw and Schulze, 1989). background. Valenciennes River area. VALENCIENNES RIVER PIPES (MARK CLAIMS) (82N/15) Four or more diatremes and numerous dikes intrude Upper Cambrian rocks nearthe headwater of Valenciennes River (latitude 51"47'0O"N, longitude 116"58'00'W, Fig- ures 64 and 67). Two distinctly different diatreme types are present. The first are rusty brown to pale green weathering, weakly to well-foliated, composite pipes with both massive and breccia phases. Two such diatremes are exposed at the southern end of the area examined. Serpentinized olivine macrucrysts (Plate 41). coarse nonmagnetic oxides(green spinels) and altered spinel peridotite xenoliths are present in some phases. Typical breccias contain 30 to 40% clasts, mostofwhicharesmall(l-5cm,withamodeofZcm),with rare xenoliths up to 15 centimetres across. Limestone, dolostone, shale and minor quartzite comprise the majority of the breccia fragments. Rare oxide macrucrysts may be present. The matrixis typically light green to grey in colour and contains calcite and/or dolomite, quartz, chlorite, muscovite, and traces of pyrite, apatite, talc and clay minerals. Bright green mica is commonly seen in band sample (chrome-rich muscovite?). Chromite and ilmenite have been identified in heavy mineral separates and a mi- crodiamond is reported to have been recovered from the largest diatreme (Northcote, 1983a). Associated dike rocksare fine to medium grained, rusty to dark green weathering, with a light greenish grey tome- dium greenfresh surfaces. They occur in a number of ori- Plate 43. Altered phenocrysts (zonedpyroxenesfolivinehica) in entations, varying from almost concordantto discordant to a dike, Valenciennes River area. "be degree of alteration in this bedding. Dikes which are nearly parallel to bedding and sample is typical. Long dimension ofthe photograph is 2.5 mm.

" Bulletin 88 83 cleavage are strongly baudinaged (Plate 42). Some of the dikes are porphyritic and all are altered. The phenoclystas- semblage, so far as can be recognized, consists of sieve-textured olivine pseudomorphs, altered euhedral clinopyroxene withrelict zoning, mica and rare spinels. Pla- gioclase phenocrysts havealso been observed (Ijewliw and Schulze, 1989). In some phases, olivine appears to he more abundant than pyroxene (olivine+pyroxenehica) and in others pyroxene is far more abundant (py- roxenekolivinehica). Some dikes are predominantly micaceous. It is difficult to accurately estimate proportions of phenocrysts as they are altered and onlymorphology canbe used plate 43). The groundmass generally consists of very fine grained carbonate, chlorite, serpentine and altered biotite (Ijewliw and Schulze, 1989). Oxides are also a common groundmass constituent. The dikes are generally peripheral to the diatremes, but locally crosscut them. The second typeof breccia is present in the diatremes in the northern part of the area examined (Figure 67). They are brown weathering and moderately wellfoliated with angular to subangular fragmentsof sedimentary rock set in a matrix ofquartz grains, chlorite and carbonate. Clasts average 1 to 5 centimetres across, with some upto 20 centimetres. The clastmatrix ratio is 2:3. These diatremes are similar to the orange-weathering pipein the Bush River area (the first type described). Intense alteration makes petrological classification dif- Figure 68. Geology of the HPpipe, southof the Campbell Ice field. Details on breccia and dike phasessupplied in Table 15. See text ficult. The rocks in the Valenciennes River area, as evi- for geographic coordinates. denced by phenocryst assemblages in dikes (olivine, clinopyroxene,mica, plagioclase) also bear astrong resem- in the Golden - Columbia Icefields area (Figure 64).It is blance to those in the Bush Riverarea and probablybelong located approximately 50 kilometres due north of Golden to the calcalkaline or alkaline lamprophyre clans. The best and is exposed at an elevation of 2400 metres, near the toe designation appears to be as olivine kersantites, which are of the Campbell Icefield. The pipeis small, covering an area part of the calcalkaline lamprophyre familyor, alternatively, biotite camptonites, which arealkaline lamprophyres. of only 40 by 70 metres; however, it is exposed in a flat, recently deglaciated basin which offers nearly 100% expo- THE HP PIPE (82N/10) sure and is therefore ideal for study. The pipe has sharp, steeply dipping contacts with the The HP pipe (latitude 5l04l'3O"N, longitude horizontal to shallow-dipping grey Cambrian limestone 116"57W) is the most southerly diatreme so farrecognized beds which it intrudes (Figure 68). It is a composite dia- TABLE 15 FELD CHARACTERISTICSOF HP PIPE BRECCIAPHASES

84 Geological Survey Branch Plate 46. Optically zonedandradite garnets, HP pipe. Long dimension of thephotomicrograph is 2.5 mm. C!arbonate PIate 44. Sharp contact between breccia phases(82 & 3), HPpipe. segregation forms matrix.

Plate 45. Large gabbroic xenolithin a strongly foliated breccia(BI Plate 47. Biotite macrocryst coring spherical smclure, HP pipe. phase), HP pipe. Long dimensionof the photomicrographis I mm. TABLE 16 CHEMICAL ANALYSES- GOLDEN AREA DIATREMES -

Si02 TI02 A1203 Fe203 0.14 0.13 0.18 0.06 0.17 0.12 0.13 0.18 0.18 0.06 0.12 0.12 0.06 0.16 13.21 11.79 8.67 5.18 9.69 14.67 11.03 12.27 12.79 6.16 6.51 9.48 5.02 7.25 19.92 20.39 17.41 17.74 16.15 13.28 9.48 16.11 13.36 14.51 11.28 12.36 15.61 12.77 0.29 0.27 1.65 1.87 0.25 0.06 0.42 1.32 1.60 0.06 2.73 0.29 0.01 0.18 4.47 4.18 4.131 1.01 0.064.1311.014.184.47 0.01 1.3610.934.0310.53 0.21 0.70 3.70 0.601 6.44 10.70 7.27 16.29 19.88 16.02 14.05 7.71 5.84 14.50 11.73 14.08 16.11 13.90 P205 0.58 0.61 0.95 0.74 0.81 0.77 0.47 0.88 0.65 0.42 0.11 0.04 0.09 0.07 0.790.02 0.11 0.16 0.08 0.07 0.08 0.20 0.04 0.31 Tora, 98.4597.54 97.63 98.95 1,401 98.66 98.8998.93 99.43 99.02 98.99 98.93 98.88 98.21 99.630.051 0,581 0.91~ 240 210 140 150 330 200 200 270 230 200 270 230 200 786 904 3131101 335 301 805 386 493 527 849 399 589 744 387 co 40 40 38 30 42 55 43 45 4j 48 38 36 56 40 137 121 130124 4039 17<8 112 3 <8 12 85 5 SI 99s lizi lis51 579 881 5281191 1410513595 640 1026 821 781 Ba 19331868 3131; 390 202 37911975 514 2136 360 91 227 322 589 Zr 191244 188 361345 229160 265 112 198 312 96 Nb156 175 172 294301 262204 200 140 229 338 111 Y 17 24 34 31 :z: 20 22 22 26 25 29 24 24 26 18 La 90 78 261 92 121 91 78 197120 119 162 165 145 123 Ce 181 169 193 208 149171 321206 247 267 29 1 27 8 220 Nd 4491 Yb <-41 3 <-2 1 0 0 0 <-2 c- 1 28.2 26.1 34.3 35 31.3 3335 34.3 26.1 28.2 25 28.8 31.1 25.1 617 18 6 10 9 3 11 11

~~7 A1.. 4 _.17 "7X _.14 0 23 33 h31I 21 10 15 14 12 14 15 106. 21 7 3IL.^ 16 356 305 339 232 306 322 206 221206 322 306 232 339 305 356 189278 57 49 67 49 110 57 109 80 65 69 7 83 7330 215~~

"_ "_ 86 Geoiogicai Survey .Trunci Minisfry of Energy, Mines and Petmleum Resoumes treme, comprising five distinctly different breccia phases garnet. In thin section, all phases contain some, ,:enerally and numerous dikes. The breccias differ in clast-to-matrix fine-grained, garnet. ratios, megacryst ahuudances@lack salitic pyroxenelgreen The HP pipeis unique, in many respects, from the other diopside/biotite) and the presence or absence of additional pipes in the Golden area. Petrography and mineralchemis- phases such as oxides and spherical structures (Table 15). try suggestthat it isan ultramafic lamprophyre withailliitic Contacts between breccia phases may he gradational or affinity. There also appears to be a significant metasomatic sharp (Plate 44). A well-developedfoliation, at high angles or metamorphic overprint introducing phases such as to the pipe's eastern and western margins, is present in melanite/andradite and clinoamphihole. phases B1 and B2 (Plate 45). The other phases aremoder- ately to weakly foliated. GEOCHEMISTRY OF DIATREMES AND The matrix of breccia phases B1, B2 and B3 is com- RELATED DIKES posed of calcitefbiotitQcolourless clinoamphihole (tremolite?)>chlorite. Serpentine, talc and pyrite are also Diatreme breccias and dikes in the Golden area are nl- reported to he present (Ijewliw and Schulze, 1989). Fine- trahasic; silica values predominantly range from2 0 to 40% grained spinel and garnet are disseminated throughout. The (Table 16) with theexceptionof dikes from theVa1f:nciennes garnets are suhhedralto euhedral in outline, light green to River area which contain from40 to 45% silica. Analyses golden or brown in colour andoften optically zoned (Plate are varied with respect to the other major elemenrs (Figure 46). X-rayspectra indicate that the brown garnet is melanite, 69; Table 16) and chemical classification is difficult. Altera- a titanium-bearing andradite, and the green gamet is tita- tion is intense, and may have affected some elemmts more nium-free andradite (Ijewliw, 1986, 1987). In addition to than others (e& potassium, as is suggested byth~: fact that most micas havebeen strongly altered and potassium may small disseminated garnets, larger garnets commonly occur in dikes and associated with calcite segregations in clast and have been removed). Ingeneral, analyses plot in or near the spherical structure-supported breccias, Groundrnass spinels alkaline to ultramafic lamprophyre fields (Wgurw 69 and are titanium-bearing magnetites. The groundmass has a 70); the HP pipe borders on alnoitic in composit:on, dikes magmatic texture, hut apparently has been altered, eitherby from the Bush River area and from Mons Creekfall more metamorphism or metasomatism. The matrixofthe spheri- within the alkaline lamprophyre range anddikes from the cal structure-rich breccias is predominantly calcite with or Valenciennes River area (all strongly altered) trend toward without amphibole (colourless to slightly bluish). Euhedral a basaltic composition. garnets commonly form rims on the spheres. The spheres As is the case with major element compositims,trace are composed of material similar to the matrix of the other element ahundancesin diatremes anddikes from the Golden breccia phases and are commonly cored by pyroxene or area are quite varied. There is a fairly wide rangeic elements mica megacrysts(Plate 47). such as chrome (Figure 7 l), strontium, rubidium andbarium (Table 16). The HPpipe, in general, shows more restricted Black clinopyroxene(salite; C.E. Fipke, personal com- compositions than the others, has higher averagerubidium, munication, 1987)bright green chrome diopside andbiotite strontium and barium concentrations and has much more are the dominant megacrysts. The black clinopyroxenesare restricted total strontiummhidium ratios (Figure7 2). Rocks rich in titanium (up to 2.6%) and aluminum (upto 14.5%). from the Valenciennes River and Bush Riverareas generally The clinopyroxenes are compositionally similar to those show the most variation and havelarge ranges in total stron- found in the Isle Bizardalnoite and in South Africanolivine tium:ruhidium ratios, which maybe indicative of higher de- melilitites. Biotite x-ray spectra show high ironmagnesium grees of alteration. Rocks collected from BushRiver were ratios and occasional zoning to iron-rich rims. Red-brown more enrichedin titanium than those from elsewherein the chrome spinels with minor amountsof aluminum, magne- Golden area (Figure 72). sium and titanium have also been identified. The spinels have a very limited compositional range; Fe2+/(Fe2++Mg) Although chemistry alone is not sufficient grounds to values of 0.34 to 0.38, Cr/(Cr+Al) values of 0.54 to 0.68 and classify rocks, especially altered rocks, it does ba2k nppet- Ti02 of less than 1%. The spinels are also compositionally rographic observations. The HP pipe appearsto share many similar to those from Isle Bizard. Euhedral apatite phe- characteristics with ultramafic lamprophyres; the other nocrysts are also present (Ijewliw, 1987; 1,jewliw and pipes and dikes in the Golden area are slightly different, in Shulze, 1988). general more similar to alkaline lamprophyres. The breccia pipe and surrounding sedimentsare cut by GEOCHRONOLOGY numerous dikes (Figure 68). The dikes are generally fine grained andmassive, but are variable with respect to xeno- In the Golden area, the HP pipe and some01' the dikes lith, macrocryst, spherical structureand obviousgametcon- in the Bush River area are relatively unaltered and contain tent. Dl dikes are massive and free of inclusions. They abundant micas. These two locations were sampled, mica contain biotite and spinel phenocrysts; the biotites are often separates obtained and potassium-argon and ~uhidinm- aligned (flow foliation?). D2 dikes have some (less than 5% strontium analyses performed in order to establish the age total) small limestonexenoliths and macrocrysts;they may of the intrusions. Elsewhere, the rocks are either loo altered also contain minor amounts of spherical structures. D3a or too poorin mica to attempt to date. Biotites from th~:HP dikes are megacryst rich (1520%); D3h dikes are also pipeyieldpotassinm-argondatesof39lf12and396flOMa megacryst rich and containspherical structnres and visible (Appendix 2). Initial rubidium-strontiumanalyse; yielded a

- Bulletin 88 87 date of 34W7 Ma; these analyses were rerun, using amore accurate ion-exchange technique anda new date of approximately 400 Ma was obtained (Appendix 2). Close agreement of potassium-argon and rubidium-strontium dates suggests that the HP pipe was emplacedat approximately 400 Ma. Recent paleomagnetic work (Symons and Lew- chnk, in press) established that samples fromthe HP pipe, after tilt corrections, give a concordant Mississippianpole, which is slightly younger than the isotopic age. Preliminary results of rubidium-strontium ion exchange analyses of micas from alkaline dikes in the Bush River area suggest an ageof 410 Ma (Appendix 2), which is in close agreement withresults from the HPpipe. Zircon separates were obtained from rocksin the Va- lenciennes River, Lens Mountain and Mons Creekareas. In all cases, the zircon populations are very heterogeneous. Zircons from the Mons Creek area vary from rounded, frosted, colourless to pale yellow spheres, to clear, equant fragments. In the Valenciennes River sampleszircons vary in shape from round to rounded prisms. Some grains are rounded andbroken. Colours range clear from to colourless, frosted to pink. In the Lens Mountain sampleboth clear and

~~/ A (NozO+K20)~~

~~Figure 70. Major element ternary plots, Golden diatremes.~~

A HP 25.00 4 Mark * Lorry * Mons 1500.00 20.00 (Mark) a1noite from Alno 1 I u15.00 Averoge 1000.00- alkali-olivine bpsalt , E v a ! 10.00 (alkaline larnprophyre) a Average mei1titite & naphslinito ._ z bosalt 500.00- 5.00

~~0.00 2 mm 500.00 1000.00 1500.00 I Cr wm Figure 69. Major element discriminant diagrams,Golden diatreme swarm. Figure 71. Ni vs Cr plot,Golden diatremes.~~

~~88 Geological Survey Branch Ministry of Energ3 Mines and Petroleum Resources~~

pink rounded zircons are present, as well as clear, frosted to clear, colourless, rounded prisms. Euhedral zircons from Mons Creekyielded .1 concordantlead-lead ageof 469iz17 Ma(Appendix 2), which possibly represents the age of zircon crystallization in the lamprophyricmagma. This maybe equivalent to, or slightly older than, the actual age of emplacement. This dzteis consistent with the fact that the igneous rocks are hosted by Lower to Middle Cambrian strata. Rounded zircons from the same sample gaveages of 1917 to 1907 Ma(Appendix 2); these zircons are clearly xenocrystic and thedates may be representative of the age of the basement. . Zircons separated from a diatreme in the Va1,:nciennes River area are all xenocrystic in origin and gavelead-lead 0.00- 0.00- ages of approximately 1525,1825,2550 and 2565 Ma (Ap- 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 pendix 2). All analyses are discordant. Zircons separated Sr/Rb from the Lens Mountain sample werealso all xlnocrysts. Resultant lead-lead ages are approximately 1790,2050 and Figure 12. SrRb vs Ti&, Golden diatremes and related dikes. 2685 Ma (Appendix2).

~~Bulletin 88 89 British Columbia -~~

~~LEGEND~~

p' mHelikian PurcellSupergroup, 1' andHadrynian Windermere Supergroup aCarnbrian aUpper Cambrian/Lower OrdovicianMckay Group throughOrdovician and/or SilurianBeaverfoot Frn. aMiddle Devonian: Cedared, Burnaisand Harrogate Fm. Middleand/or Upper Devonianthrough Mississippian mPerrnianand Pennsylvanian, Rocky MountainGroup mTriassicand Jurassic or younger

~~0 Alkalicultrabasic diatreme ordike location~~

~~1 JoffPipe 2 Rus Pipe 3 MaryCreek-White River brecciadike 4 BlackfootDiatremes 6 Swanson Peak volcanics anddiatreme (Swan Claims) 6 QuinnDiatremes 7 Summer 1 & 2 Pipes 8 CrossingCreek Kimberlite~~

~~0 15 Kilometres~~

~~Figure 73. General geology and diatreme locationsthe Bullin River - White River area. Geology modified from Leech(1960, 1979) and Price (1981).~~

~~~- 90 Geological Survey Branch Ministry of Energy, Mines and Petroleum Resources~~

~~ULTRABASIC DIATREMES IN THE BIJLL RIVER - ELK RIVER AREA, SOUTHElRW~~

~~BRITISH COLUMBIA (82Gr," 3)~~

Forty or more breccia pipes and related dike-rocks oc- ing fine-grained altered clinopyroxene and somefeldspar. cur within the Bull, White and Palliser river drainages (Fig- Microprobe analysesindicate that the feldspar is e:;sentially ures 2 and 73) east of Cranbrook and Invermere (Grieve, pure albite; the albite, however, may be secondary, having 1981). The majority are hostedhy the Ordovician-Silurian Beaverfoot Formation and underlying MountWilson andlor replaced an earlier, more calcic plagioclase or potassium Skoki formations andexhibit similarities in petrography,de- feldspar. Some feldspar laths have been partially altered to gree of alteration and morphology. white mica or clay minerals. Some mafic phenocrysts have been pseudomorphed byquartz andchlorite. Opaqile oxides SHATCH MOUNTAIN AREA(JOFF are abundant. CLAIMS) (825/11) A number of small diatremes anddikes have been reported (D.L. Pighin, personal communication, 1984) south of the Palliser River on the ridges around Shatch Mountain, west of Joffrey Creek (latitude 50"31'07"h', longitude 115"16'33'W) approximately 55 kilometres east of In- vermere (Figure 73). Two were examined, both exposedat the 2750-metre elevation and accessible by helicopter. Both are hosted by moderately to steeply east-dipping Ordovi- cian-Silurian Beaverfoot-Brisco strata which are charac- teristically massive thick-bedded grey limestones which contain rugosan corals. The main breccia pipe (Figure 74) consists of small (up to 10-centimetre) subrounded to subangular fragmentsin a strongly foliated light green matrix. Clasts are predominantly limestone, dolostone andshale; some cognate xenoliths and rare pyroxenite nodulesare present. In thin section, honey-coloured altered vesicular glass lapilli are the predominant constituents; locally the glass is completely devitrified. Juvenile lapilli are also present and in some samples quite abundant. The matrixof the breccia consists of calcite with some quartz and chlorite and minor talc, anatase and apatite. This is a tuffisitic crater-infill breccia. East (stratigraphically up-section) of the main breccia, intensely hematized, discontinuouslayers consisting of juvenile lapilli, suhangular lithic fragments, quartz and carbonate are apparently interbedded with grey limestone. These agglomeratelayers locally display moderate to well- ;DIMENTARY SEQUENCE INTRUSIVE AND RELATEC developed graded bedding (Plate 48). Elsewhere, graded SEQUENCE DOLE AND/OR UPPER DEVONIAN breccia layers are immediately overlain by pink and huff a8ASAL UNITpink and bull dolostones, sandy crosshedded dolostones andsandstones, Eandrlone. dolonfone. mudstone and 101uIion breccia well-bedded siltstones and dolomiticsiltstones of the basal ~OOV~C~AN/SILUR~AN Devonian unit (Plate 49). a8EAVERFOOT FORMATION: -Epicloolic ond/or pyro~laslic lhiok bedded. grey tuff breccia beds South of the main tuffkitic breccia, a medium to fine- forsilifemus limerfane -Folioled tuf,isilic brecc ~ grained, massive igneous intrusive crops ont (Figure 74). -Marrive. magmoiis phase that is medium to dark greenin colour withintensely hrec- ciated and hematizedmargins. It contains 10 to 15%altered Figure 14. Geology of theJoff pipe, Shatch Mountain area clinopyroxene andolivine phenocrysts in a matrix contain- (modified from Pell, 1986a). See text for geographic coordinates.

~~Bulletin 88 91 British Columbia -~~

Due to intensity of alteration, classification is diffidt. The presence of glass lapilli and absence of biotitdphlo- gopite exclude these rocks fromthe ultramafic lamprophyre clan. The phenocryst and microphenocryst assemblage of olivine, two generations of clinopyroxene and a mall amount of feldspar (albite) in the groundmass of the porphyrytic dike-rocks suggest that they mayshare some affinity to limburgites or alkaline basalts. THE RUSSELL PEAK DIATREMES (825/6) Diatremes in southern British Columbia aretypified by those near Russell Peak (latitude 5Oo25'40"N, longitude 115"13'30"W, Figure 73). There are at least three small pipes in the immediate vicinity of Russell Peak, two more small intrusions crop out approximately7 kilometres to the north (latitude 5Oo29'15"N, longitude 115°15'40'W). All of these pipes can be reachedby helicopter from Fairmonr. Hot Springs. One, immediately southof Russell Peak, is particularly well exposed on a cliffface anddisplays many feawes of pipe morphology (Figure 75). The lower poaionof the exposed pipe compriseswell-foliated, tuffisitic breccia containing abundant subangular fragmentsof sedimentary rock Plate 48. Graded bedding in extrusive epiclastic layer,Joff pipe.

~~mC0orz.e contactbreccia Dialreme material/tuffite Epiclarlicand/or pyrocioslic a materialmixed withsediment =Mafic volcanic rock Snow patch 0Limestone rafts~~

Db = Basol Devonian unit Ob = Ordovician Beaverfoot Formation . Otp = OrdovicianTipperary Plate 49. Epiclastic crater-infill breccia, Joff pipe, immediately Formation L-3 overlain by well-bedded, pink and buff-weathering strata of the Metres basal Devonian Unit, (colourphoro, page136). Figure 75. Geology of the Russell Peak diatreme. ,.

92 Geological Survey Branch and subrounded cognatexenoliths (autoliths) in a matrix of A small, black-weathering, mafic body (flc~w?)out- vesicular altered glass lapilli, monocrystalline quartz crops nearthe exposed top of the crater zone (Figwe75) and xenocrysts, calcite, dolomite, chlorite, minor talc, serpen- represents the only unaltered material present ir. the dia- tine and opaque oxides. Exotic material is rare, if present. treme complex (Plate 51). It is extremely porphyritic and Rock fragmentsup to25 centimetres across are present, but comprises 5 to 20% titanaugite (Appendix 3) and,approxi- the population mode is 2 centimetres and the clastmatrix mately 10% altered olivine phenocrysts set in a ma.trix of35 ratio is approximately 1:l. The tuffisitic breccia is medium to 40% titanaugite microphenocrysts, 0 to 5% olivine, ap- green in colonr except alongthe pipe walls where it isred, proximately 10% altered feldspar and 5 to 10% opaque ox- due to the presence of abundant hematite. At the western ide microphenocrysts with 15 to 25% finegained margin of the pipe, near the base of the exposure, a coarse groundmass. The groundmass, in part, consistr. of fine- contact breccia crops out. It contains large (up to 4 or 5 m), grained material of essentially albitic composition. Some chaotic fragments of angular wallrock and subordinatema- quartz and calcite are present as alteration minerals. Micro- trix. probe analyses indicate that some essentially unaltered Between 50 and 100 metres of well-bedded, greenish labradorite is present (Appendix 3) together u.ith trace weatbering pyroclastic and/or epiclastic material (Plate 50) amounts of chrome spinel. In a nearby diatreme, similar ma- is exposed overlyingthe tussitic breccia. At the base of this terial occurs as small dikes crosscutting diatreme-zonetuf- zone, the material is similar in composition to the tuffisitic fisitic breccia, suggesting that this phase was emp:acedlate breccia, with increasing amounts of sedimentary material in the intrusive sequence. and interbeds of dolomitic siltstone or silty dolostone, up- The modal mineralogy of the magmatic g'hase (ti- section. Thin layers of igneous material are apparently in- tanaugite and olivine phenocrysts, titanaugite, olivine, terbedded with, or injected into, the Ordovician-Silurian labradorite and opaque oxide microphenocrysts In a fiue- Beaverfoot Formation carbonate rocks, near the top and margins of the exposed pipe. The succession is unconformably overlain by Middle and/or UpperDevonian strata.

Plate 51. Porphyritic volcanic rock, Russell Peak diatreme. Large euhedralgrains are zoned, titaniferious clinopyroxene phenocrysts:the large anhedral crystal is ana1teri:d olivine phenocryst; the microphenocrystpopulation cmsists of titaniferous clinopyroxenes, feldspar laths and opaqle oxides. Plate 50. Well bedded craterinfill material, Russell Peak diatreme. Long dimension of the photo micrograph is7 mrn.

Bullefin 88 93 grained groundmass) suggests that these rocks haveaffinity BLACKFOOT ANDQUINN DIATREMES to limburgites or alkaline basalts, but do notfit exactly into (826/14) either category. They differ from limburgites in that the feld- The Blackfoot diatreme crops outat 2650 metre!; ele- spar present is calcic (labradorite) rather than sodic. They vation on ridges east of the headwatersof Blackfoot (!reek exhibit some mineralogic similarities to basanites or (latitude 49"58'23"N, longitude 115"16'45"W) approxi- tephrites (alkaline basalts), but lack modal feldspathoids mately 65 kilometres northeast of Cranbrook (Figurf: 73). Access is by helicopter or on foot from a logging roadin the and contain considerablyless feldspar than commonlypre- Blackfoot - Quinn Creekvalley. TWO small diatreme!; (the sent in these rock types. Quinn pipes) are present near the head of Goat Creek, a tributary of Quinn Creek (latitude 49"53'05'N, longitude 115°20'30"W). One is exposed westof Goat Creek, at approximately 1980 metres elevation and can be reachcdby hiking along Goat Creekfor slightly less than a kilometre from the end of alogging road. The other is exposed e,xst of Goat Creek,in asaddle at 2315 metreselevation and i:;best reached by helicopter. These pipes are very similar to the Blackfoot diatremeand will be discussed together with it. The Blackfoot pipe is a recessive, green-weathering body, discordant with rocksmapped byLeech (1960)2s Or- dovician to Silurian Beaverfoot-Brisco Formation. :.?olds are evident in the hostrocks nearthe diatreme, where there is a deviation from the regional steep westerly dips (Figure

HOST ROCKS OLimestone,shaly limestones Beaverfoot-EriscoFormation) Massivegrey fossiliferous limestones thin-beddedpurplish limestone andshaly limestone Plate 52. Vesiculated glass lapilliindiatreme breccia, Quinn;:reek. Figure 76. Geology of the Blackfoot diatreme. Long dimension of photo micrograph is2.5 mm.

~~~~~~ 94 Geological Survey llranch Ministry of Eneqy, Mines and Petroleum Resorrrces~~

76). The Beaverfoot-Brisco Formationin the hangingwall Haynes - Swanson Peakarea (latitude 49°5620", longitude is characterized by thick-bedded, massive, medium grey 115"16'3O"W). Igneous rocks outcrop at approximately limestones containing rngosan corals, and light grey lime- 2400 metres elevation and can be reached by hekopter. stones in which chain corals (favosites and halosites type) Extrusive flows and a small diatreme arc: exposed are present. Thin-bedded to laminated, nonfossiliferous, within a few hundred metres of each other. The main flow purplish weathering limestones and shaly limestones are is approximately metres thick. It overlies a'l orange- present in the footwall. The contacts between the diatreme 3 weathering, coarse, intraformational limestone cimglomer- and the limestones arewell exposed andno thermal meta- graptolitic shale. The volcanics are morphic effects are evident. ate that, in turn,overlies overlain by a few tens of centimetres of mixed shaly tuff The Blackfoot diatreme is a composite or branching which is in turn overlain by a thin orange-weatheringquartz- pipe-like body that is intensely foliated near its margins and ite. The quartzite displays graded beddingand, lit its base, contains fragments that have been flattened in the plane of contains small (centimetre-size) greenish clasts Df the un- the foliation. The centre of the diatreme is moderately to strongly foliated. Foliation is generally parallel or subparal- derlying volcanic rocks. The quartzite is overlaiu by a thin lel to the margins (Figure 76). This wasapparently a site of black shale unit which is inturn overlain by 1.5 to 2 metres localized shearing during deformation. This pipecontains of white to pinkish weathering orthoqnartzite (Figure 77). approximately 30%inclusions, most of which are sedimen- Thin to thick-bedded grey carbonatesof the Beawrfoot For- tary in origin (largely limestone, some shale and dolostone). mation, containing abundant fossil corals, orerlie the These inclusions are subronnded to subangular and geuer- quartzite. The stratigraphic position of this flow, .which un- ally small (up to 10 cm in diameter). The largest xenoliths are purple-greyto huff-weathering carbonatesprobably derived from the Beaverfoot-Brisco Formation. The Quinn STRATIGRAPHY-SWAN CLAIMS pipes are very similar in appearance and composition, hut somewhat less deformed.

Exotic xenoliths, predominantly clinopyroxenites, greycarbonate hornblendites and dunites, are relatively common and re- markably fresh. Eclogite nodules have also been reported Beaverfoot-BrircoFormation (C.I. Godwin, personal communication, 1984). Clinopy- coral* locally prerert roxenite nodules consist of 30 to 57% green diopside, 0 to - 3 15% enstatite, 0 to 40% olivine plus serpentine, 0 to 22% hornhlende with calcite, talc and minorilmenite, spinel and pyrite. Hornblendites contain approximately 75% hornblende, 10% clinopyroxene and 10% ilmenite, with calcite, 2 serpentine and traces ofpyrite. Dunitescontain 63% olivine, whiteorthoquartzite L1 +? 14%clinopyroxene and 17% talc with accessory orthopy- ...... roxene and hornblende (Ijewliw, 1986). Exotic xenoliths E were not found in the Quinn pipes. 1 Altered vesicular glass lapilli, yellow in colour,are pre- black shale sent in the breccias (Plate 52), as are juvenile lapilli. The 0- glass lapilli are extremelywell preserved inthe Quinn pipes. orangequortzite with Lapilli constitute about 25 to 30% of the rock volume. Diop- green CILIDIO near tl(lLB side, altered olivine, minor orthopyroxene and chrome greyshale and greanish spinel macrocrysts are also present. The matrix, which fragmentols makes up asignificant proportion of the sample volume, is amixtnreofcalcite>talc?chloritekplagioclase,minorpotas- sium feldspar, sphene andapatite with a fibrous, matted texture. Bryozoan and brachiopod fragments havebeen noted greenvolcanic locally sheared from tnffisitic material in the western Qninn pipe. Massive, fine-grained, dark cut thebreccias centralportion appears green dikes pillowed at both the Blackfoot andQninn diatremes. These dikes are intensely altered. The Blackfoot and Qninn diatremes are extremely similar to both the Shatch Mountain andRussell Peak pipes and are therefore probably also of limburgitic or alkaline basaltic affhity.

MOUNT HAYNES - SWANSON PEAK orange weothering(+domitic? AREA (SWAN CLAIMS) (826/14) intraformoiionolconciomerate The Swan claims arelocated approximately 5 kilometres south of the Blackfoot pipe (Figure 73) in the Mount Figure 77. Stratigraphy, Swanson Peak area

Bulletin 88 95 Plate 53. Pillowed flow, Swanson ]?e&, derlies 5. quartzite (Tipperary Formation?) beneath the THE MARY CREEK- WHITE RIVER Beaverfcsot Formation, indicates that it is of probable Late BRECCIA DIKE (82Jj3W) Ordovician age. The flow is fine grained and dark greenin hand sample. A narrow dike crops outat the head of Mary Creek, a Spherical pillow strnctures are preserved in the centre of the small tribufary ofthe White River, east of Whiteswan Lake unit (P1a:e 53). In thin section, the rock displays a fine por- (latitude 5O01O’3O”N, longitude 115”22’15”W; Figure 73). phyritic texture consisting of approximately 10% altered It is exposed at the 2010-metre elevation and is most easily accessed by helicopter. olivine @pyroxene?) phenocrysts and2 to 5% feldspar phenocrysts in a he-grained altered groundmass that contains The di.ke is 1 to 2 metres wide, steeply dipping and approximately 40% feldspar microphenocrysts and a few slightly discordant to bedding. It mainly consists of a mas- percent opaque oxides. Microprobe analyses indicate that sive, fine-grained, dark green weathering phasethat locally the feldspars, both phenocrysts and microphenocrysts,are grades into a red and green-weathering, strongly foliated phase that contains small round globularsegregations or ac- very pun: potassium feldspars (Appendix 3). cretionary :lapilli. The massive phaselocally contains clasts The diatreme is exposed on a small ridge, approxi- of host sedimentary strata. In thin section, accretionary mately 200 metres southof where the volcanics outcrop. It lapilli were observed to be cored by olivine macrocrysts is light greenish to buff weathering,massive, and hasa grey- with large red-brown spinel inclusions; some fine-grained ish to buff fresh surface. It consists of a matrix-supported biotite was also noted. breccia that predominantly contains small, subroundedfrag- ments of sedimentary rock. THE SUMMER PIPES (826/11) Bas-d OTI the modal mineralogy (olivineAc1inopy- roxene andtw’a generations of potassium feldspar), the vol- Two small intrusive bodies are exposed at the conflu- canic rock is difficult to classify; it exhibits similarities to ence of Galbraith and Summer creeks (latitude 49’44’50’’ the trachybasalt or the nephelinite family of rocks, butcon- longitude 1.15°20’32’W, Figures 73 and 78) approximately tains potassium feldspar alone rather than with plagioclase 40 kilometres northeast of Cranbrook. Outcrops occur be- in the fo~mer,!or feldspathoids, in the latter case. It is impos- tween 1250 and 1350 metreselevation and canbe reached sible to :say, however, if the potassium feldspar is primary from a logging road leading to a forest recreation site at or pseudomoq?hing a pre-existing phase. Summer Lakeand to the Top of the World Park. These pipes

~~96 Geological Survey Branch Minisfry of Energy. Mines and Petroleum Resources ”~~

have beenpreviously reported on by Grieve (1981) and Pel1 (1987). The Summer diatremes formrusty weathering resistant knolls and arehosted by rocks mapped by Leech (1960)as Late Cambrianto Ordovician McKay Group. In the vicinity of the diatremes, the McKay Groupconsists of thin-bedded, grey micritic limestone, argillaceous limestone andintrafor- mational limestone conglomerate.In only one place is the contact between limestone andbreccia exposed and there, is subparallel to bedding in the limestones. This is most likely a local phenomenon, as the overall outcrop pattern indicates discordance. The limestones within0.5 metre of the ex,posed contact are strongly brecciated and material similar to the diatreme matrix forms veinlets in the limestone breccia. No other contact effects areevident. The breccia pipes consist of angular to snbrounded clasts in a medium green to grey matrix which is locally calcareous.Theclast:matrixratioisontheorderofl:l,with clasts ranging from granuleto cobble size. The largest and most numerousinclusions are angular limestone, limestone conglomerate and shale fragments, up to 70 centimetres across, which comprise 90%of all the clasts. The remaining 10% are buff dolostones, crinoidal limestones, red-weathering, thinly laminated dolostones, granites, granitic gneisses, phlogopite - chrome mica - marbles (altered syenites?), fine-grained cognate xenoliths and autobreccia fragments. Resistant reaction rims were noted aroundmany sedimentary clasts. The matrix is predominantly chlorite, serpentine and carbonate (Grieve, 1981). Abundant juvenile lapilli (20-40%) and altered olivine and clinopyroxene macrocrysts are evident in thin section; some of the lapilli are Plate 54. Chrome spinel macrocryst (dark crystal rimmedby light cored by altered feldspar or clinopyroxene grains. Minor coloured tc, transparent minerals - mainly carbonates), Summer chrome spinel may also be present (Plate 54). No vesicular diatnme breccia. Long dimensionof the photograph is 2.5 mm. glass lapilli were observed. TABLE 17 CHEMICAL ANALYSES BULL RIVER - ELK RIVER DIATREMES AND RELATEDROCKS

~~,724.-~~

~~Si02 Ti02 A1203 Fez037 MnO 0.19 MgO 5.85 , cao~~

~~~ Nd.0 K20 LO1 E05~~

480 140 420 420 80 160 140 490 400 480 2w 3W 210 158 380 520 430 280 200 85 116 340 754 236 579 564 176 201 476 8115 592 1050 542 709 508 450 898 994 1454 47 1 134 237 131 540 40 32 33 30 30 51 42 34 45 47 48 56 50 42 43 52 40 39 36 8 32 43 8 22 5 11 21 16 6 <8 26 11 40 33 18 46 4

~~@ Diotreme breccia by /\ Swonron Peak~~

~~Figure 79. Major elementternary plots. (A) Fez03-MgO-AIz03 plot, southern diatremes:(B) Fe?,03-MgO-A1203 plot, Swan volcanics: (C) fiF" diagram, southern pipeswarm: (D)AFM diagram, Swan volcanics.~~

Related dikes and sills occur peripheral to the diatre- slightl:, deeper level intrusions or blind diatremes of alka- mes. The dikes are fine grained, porphyritic and strongly line basalt affinity that did not breachthe surface. altexed. Theyare texturally similar to dikes and flows in the Rus:;ell Pcak area. They contain what appear to be altered GEOCHEMISTRY OF DIATREMES AND olivine, c:linopyroxene and feldspar phenocrysts and mi- DIKES crophenoc:rysts. These dikes are locally vesicular; the vesicles are rimmed bycoarse crystalline carbonate andinfilled Al.kaline rocks in the Bull River - Elk River area are with serpentine. varied in composition. Silica contents are in the ultrabasic range to marginally basic, from 28 to 45% and the aluminum Thou,!h still probably part of the same petrologic family, the Summer diatremesdiffer from those previously de- to alkali ratios place them in the metaluminousfields (Table 17). Other major elementsvary significantly (Table17: Fig- scrihed in a number of ways: they are hosted by Late nres 79 and 80). On the Fe203-MgO-Alz03 ternary dis- Cambrian McKay Formation strata, not by Ordovician-si- criminant plot, these rocks generally fall in or peripheral to lurien formations; they are massive, brown-weathering, the alkaline lamprophyre (melilitite) fields (Figure 79), weakly foliated breccias as opposed to dominantly green- while on the AFM ternary plot they plot in the ultramafic wealherin,!, well-foliated tuffisitic breccias: and theyare de- lamprophyre field and between it and the kimberlite field, void of volcanic glass lapilli. These rocks may represent generally removed from thearea of typical basaltic compo-

" Built tin 88 99 British"_ (!oluml?ia sitions (Figure 79c). Relatively unaltered dike andflow ma- tremely potassic. They do not fall consistently into one telial from the Russell Peak area plot in the alkaline lampro- category on the various discriminant plots: on the FeZ03- phyre fjeld on a K20-MgO discriminant plot; dikes from MgO-Al203 ternary plot they fall on the aluminous sideof Mary Creek rdot thein alkaline and ultramafic lamprophyre the alkali basalt fields (Figure 79b); on an AFM diagram fields (I9gnre 8Oa). Samplesfromotherareasgenerallyhave they plot along thebasalt trend and closer to the AM side of MgO values in the alkaline to ultramafic lamprophyre the triangle than typical basalts (Figure 79d); on a KzO- range, but are depleted in potassium. On the alkali-silica MgO plot they fall within or marginal to the leucitite field plot, re1 3tivel:yfresh dike material from the Russell Peak and (Figure 80a); and, on an alkali-silica plot they fall well Mary Creek areas plots peripheral to the melilitite- within the melelitite-nephelinite field (Figure 8Ob). Major nephelhite and hasanite fields; the other samples are quite element chemistry and conventionalplots do not helpin un- vaned, :some plotting in the typical basalt field and others equivocally classifying the Swanson Peak volcanics; they exhibiting a depletion in alkalis relative to alkaline lampro- do, however, suggest that these rocks share some chemical pbyres (Figure Sob). Much of the scattering of chemical similarities with members of the nephelinite family, al- compos.tions may, in part, be due to alteration or to dilution though lackingin modal feldspathoids. from inciorporation of foreign material. The chemistrysug- Trace elementconcentrations of rocks fromthe south- gests th;H the,re rocks are more basic than typical alkaline em diatreme swarm are somewhatvariable, particularly in hasalts md m;iy betransitional to nephelinites, but have not terms of elements such as shontium, barium, nickel and deve1op:d modal feldspathiods. chrome(Table17).SwansonPeakvolcanicshavenickeland The volc.mic rocksat Swanson Peak havean nunsual chrome concentrations similar to typical hasalts, while dia- composition; like other igneous rocks in southern British tremes anddikes from elsewhere in the southern swarmare Columbia, thEy are ultrabasic, but are peraluminons andex- enriched in these elements (particularly in chrome) relative r to basalts lor nephelinites (Figure 81), with dikes generally more enrichedthan breccia phases. Most ultrabasic rocks in this area contain low concentrations of rubidium and lowto moderate mounts of strontium, relative to the others examined from the Golden, Ospika and Kechika areas. Total strontium:mhidium ratios for diatreme breccias throughout the area, and for dikes from the Summer area, are quite variable (3 to 1221),while dikes and flows from Russell Peak and the B:lackfoot area have restricted ranges, averaging around 22:l. The volcanics from the Swanson Peak area have higher than average rubidium concentrations and lower than average strontium concentrations compared to other members of the southern diatreme swarm,resulting in low total strontiummbidium ratios (around 2:l). On average, dikes and flowsin the Bull River- Elk Riverarea are significantly more enriched in titanium than related brec- MQO I cias; the Swanson Peakvolcanics contain moretitanium, on e Blackfoot @ Quinn, Joff 25.00- X Rus 0 Joff. Ouinn, Blackfoot 8 Summer RUES dialremes n Mary Creek 0 Rum VOIC~IEI.diker 1500.00$ 20.00- . Swan * Swan + Hayner Creek grobbroicsill

~~Average Plveroge 1000.00 alkali-olivine kimberliteo c basalt Dikaa v~lcanics Russell Peak and Summer are0~~

~~Chrome spinel rich breccia~~

~~0.00 500.00 0.00 1000.00 1500.00 Figure 80. Major element discriminant plots, southern diatreme swarm. (P.)Soulhdiatremeswarm: (B)Alkali-silicaplot, southern pipes.~~

100 Geological Survey Branch " Ministry of Energy, Mines und Petroleum Resources average, lhan the other ultrabasic rocks in the area (Table fractio,ns plotted on concordia, yielding Paleozoic ages of 17). 529 and 532S.5 Ma. Although tantalizingly young, it is unlikely that these ages are related to diatreme emplace- GEOCHRONOLOGY ment: the Blackfoot pipeis hosted by the Ordovician to Si- Diatreme breccias and related rocks in the BullRiver - lurian (circa 440 Ma) Beaverfoot Formation carbonate Elk River area for the most part do notcontain micaor other rocks. minzrals ;amenable to Rb-Sr or K-Ar radiometric dating. In As radiometric dating methods havenot yet proved use- lieu of this,other methods havebeen attempted in order to ful, age determinations mustrely on relative methods. In the establish the agesof emplacement of these rocks. Crater-in- case aF the Swanson Peakvolcanics, this task is not too dif- fill material from theRus pipe onRussell Peak was sampled ficult. The volcanics clearly underlie a quartzite unit imme- for conodonts. It was barren. Samples werecollected from diately beneath the Late Ordovician to Early Silurian the .loff pipe on Shatch Mountain and from the Blackfoot Beaverfoot Formation. Adiatreme in theNorth WhiteRiver pipe and xircon separates were obtained. Zircons recovered from the Joff pipe were colourless and rounded, with an valley is of apparently the same age. It cuts Middle Ordovi- oblate to )prismaticshape. Results of analyses indicate that cian Slkoki Formation strata and contains bedded epiclastic the :zircons are xenocrystic in origin (Appendix 2). giving crater-infill material in the upper portion of the pipe (Helm- lead-lead ages of 1046, 1780, 1820 and 2085 Ma. Two of staedt ,er al., 1988). The crater-fill sediments areoverlain by the .dnaly!;es, which yielded the oldest and youngest ages, a quantzite unit which underlies the Beaverfoot Formation, p1ot:ed very close to concordia (Appendix2). snggeriting an age of emplacement of circa 450 Ma. A ma- Zircons obtained from the Blackfoot diatreme are of jority of the other pipes in the area cut through part or all of four diffelrenr types: round and colourless; round and pink- the Beaverfoot Formation, butdo not breachthe basal De- ish; clear, colourless, enhedral and abraided; and clear, vonian unconformity surface; they are, therefore, post-Late euhcdral, multifaceted. The rounded zircons gave lead-lead Ordovician to Early Silurian and pre-Middle Devonianin ages of 1'918 and 2052 Ma (Appendix 2). The other two age, probably circa 400 Ma. "-

~~10 Pile Metres I Figure 82. Sketch of the Crossing Creek kimberlite pipe, facing north.~~

Plate 56. Altered olivine macrwrysts and phenocrysts, phlogcpite Plate 55. Pyroxenite inclusion forming the core of an accretionary phenocrysts andopaque oxides in a magmaticmatrix, Cross lapillus, central breccia phase, Cross kimberlite. kimberlite.

~~I02 Geological Survey Bmnch ,.., ~ ~~~~ ~~~

~~Ministry of Energy, Mines and Petroleum Resouxes~~

~~KIMBERLITES IN BRITISH COLU1M:BIA~~

THE CROSS KIMBERLITE (82J/2) et al., 1986; Ijewliw,1986,1987; Pell, 1987) andthe reader is referred to those works for additional details. The Cross diatremeis exposed at an elevation of 2200 The Cross diatreme intrudes Pennsylvanian-Pennian metres on the north side of Crossing Creek, 8 kilometres Rocky MountainSnpergroupstrata(Hovdebo, 19.57). It out- northwest of Elkford (latitude 5O0O5'24'W, longitude crops ona steep face and anarea of approxitmate1:y55 by 15 114"59'48'W). It is 60 kilometres east of the Rocky Moun- metres is exposed. Its western contact is wall exposed and tain Trench, or approximately20 kilometres east of the axis clearly crosscuts shallow-dippingcrinoidal dolo!:tones and of the zone containing theother intrusions in the Elk River dolomitic sandstones(Figure 82). Aminor s:hear zone forms - Bull River areas (Figure 73). It represents the only true the eastern contact. No thermal effects 011 the wallrocks were observed. kimberlite known in the province to date. Access is by helicopter or by four-wheel-drive vehicle and a hike along an undriveable road. It has previously been reported on (Meeks, 1979;Robertsetal., 1980;Grieve. 1981,1982;Hall

~~@ Creek f Crossing kirnberllts /\~~

~~10.00~~

~~5.00~~

~~0.00 0.00 5.00 10.00 15.00 20.00 -25.00 30.0~~

~~03 + Crorrtng Creek 25.00 kirnberllte @ Averoga klrnberlile 20.00 1 ponolitlc~~

~~barmillto lephrite~~

~~Iarnprophyre 5.00 bora11~~

~~0.00 " 20.00 30.00 40.00 50.00 60.00 70.00 SI02~~

~~Figure 83. Major element discriminantplots, Cross kirnberlite. Figure 84. Major element ternaryplots, Cross kinlberlite~~

~~- Bulletin 88 103 ~~ ~~~

~~Ministry of Energy, Mines and PetrooResources~~

~~ECONOMHC CONSIDERATIONS AND EXPLORATION POTENTIAL~~

Many metals and industrial minerals are either pro- al., 1986). The other British Columbia carbonatite com- duced from alkaline rocks or are known to occur in eco- plexes which have been examined all have averageNbzOs nomically significant amounts in alkaline rocks. Alkaline values of 0.30% or less, but there is excellent potentia1 for rocks are a major sourceof niobium and rare-eartb elements the discovery of other carbonatites with potential ore-grade among the metals and of nepheline, barite, vermiculite, co- niobium concentrations. rundum and diamond amongthe nonmetals. Molybdenum, Tantalum is not abundantin British Columbi:l carbona- zirconium, copper, fluorite, wollastonite and apatite are also tites. Most of the complexes have NLxTa ratios typical of recovered from alkaline rocks. The important features of carbonatites, approaching 1OO:l or more ana niobium economically significant materials in alkaline rocks in Brit- grades are never sufficient to result in signifi.cant concentra- ish Columbia are outlined in the following summary. tions of tantalum. Carbonatites in the Blue 'River area have anomalous Nb:Ta ratios, in the order of 4:l and tantalum NIOBIUM AND TANTALUM analyses of up to 2400 ppm are reported (Aaqui:.t, 1982b). On average, however, the niobium gradesat Blue River are Carbonatites contain the bulk ofthe world's reserves of low, ranging between 0.06 to 0.1% NbzOs and, therefore, niobium, a metal whichis used in the production of high- even with anomalous NbTa ratios, currently suteconomic temperature speciality steels and superalloys for nuclear, with respect to tantalum. aerospace, heavy equipmentand pipeline applications. Nio- binm also has important potential as a superconductor of RARE-EARTH ELEMENTS AND electricity at cryogenic temperatures(Cunningham, 1985a). The principal niobium mineralin carbonatites is pyrochlore, YTTRIUM although other niobium-bearing species such as columbite Rare-earth elements are concentratedl in all alkaline and fersmite may also be present. The majority of the rocks. In carbonatites they are present main'lyin the form of world's niobium, approximately 85% of total production, the cerium subgroup, or light rare earths. A considerable comes from Araxa, Brazil, where pyrochlore has been con- concentration of rare-earth elements may be contained in centrated by residual weathering and grades arc in the order common minerals such as calcite, dolomite, pyrochlore, of 3% NbzOs. In Canada, niobium is mined by Niobec Inc. fluorite, apatite, sphene and zircon. Rare-earth carbonate (Teck Corporation and Cambior Inc.) at St. 1Ionor6, near and fluorocarbonate minerals such as bastnaesite and Chicoutimi, Quebec, where gradesare 0.5 to 0.67% NbzOs. parisite, or phosphate minerals such as monazit: or xeno- Tantalum is a relatively rare, heavy, inert metal that is time, mayalso be present in alkaline suites a.nd contain rare- used in electronics, chemical processing equipment,metal- earth elements. Yttrium, although notstrictly a rare earth, is cutting tools and high-temperaturesteel alloys. It is recov- commonly grouped with themas its chemical properties are ered principally as a coproduct of other metal mining, similar to the heavy rare earths. associated with tin lodes, tin placers and beryllium-tin-nio- These elements are used principally in petroleum- biumpegmatites (Cunningham,1985b). Tantalum mayalso cracking catalysts, iron, steel and other metal-alloying be present in significant amounts in carbonatites, generally agents, glass-polishing compounds andglass add Itives, per- in the mineral pyrochlore. In alkaline rocks the Nb:Taratios manent magnetsand phosphors for television and lighting commonly exceed100, whereas in granitic rocks theyaver- (Hendrick, 1985). The rare earths also have importantpo- age 4.8 (Cume, 1976b). tential in the manufacture of superconducsm ar.d applica- Carbonatites in British Columbia areall anomalous in tions in advanced ceramics and lasers, piuticnlarly yttria niobium. The Aleycarbonatite complex appearsto have the (Wheat, 1987). The U.S.A., Australia and China are the ma- greatest niobium potential of any of the complexes so far jor producers of rare earths (Griffiths, 1984; Hendrick, discovered. Work by Cominco Ltd. since 1982, which in- 1985). Most of the economic recoveryin the U.I .A. comes cludes surface exploration and diamond drilling, has de- from the Mountain Pass carbonatite in Califonia, which fined extensive zones in both the rauhaugite core and grades 7to 8% total rare-earth oxides, predominiatly of the sovites, containing between two-thirds and three-quarters of cerium subgroup. Bastnaesite is the principal ole mineral. a percent NbzOs (K.R. Pride, personal communication, InAustraliarareearthsarerecoveredfromnlonaziteplacers; 1986) and grades whicheasily rival the St. Honor6 complex in China rare earths are recovered fromtabular magnetite in Quebec. Local areas containing greater than 2% Nbz0s iron ores, fluorite-quartz-carbonate and tungsten-quartz have been outlined in the Aley complex. At Aley,the nio- veins, pegmatites andtin placers (Lee, 1970). Recently, the bium is present mainly in the minerals fersmite and pyro- greatest demand has been for samarium andnedymium to chlore; columbite is also present in minoramounts (Pride et be used inthe magnet industry and for yttrium in:?hosphors,

~~- _" Bullelin 88 107 "_ "_~~

~~British Columbia "~~

The diatreme is lithologically heterogeneous and, lo- between phasesmay be gradational or sharp. Athin dike, 10 tally, very friable. The west end of the outcrop is a light to 30 centimetres wide, cuts the central breccia phase green, strongly foliated rock containing some redhematized Ultramafic xenoliths are almost entirely serpentinized clasts, abundant pelletal lapilli and cobble-sizedpellets, as pseudomorphs of olivine and pyroxene. Theoriginal pres- well as autobreccia fragments (westernbreccia phase). Fo- ence of olivine is indicated by the typical olivine outlin e and liation is at a high angle to bedding in adjacent sediments. fracture pattern; the grains, however are completel.11 ser- This grades eastwards to a massive, inclusion-poor light pentinized. Some relict pyroxene, withcharacteristic c:leav- green unit (western massive phase)which in turn grades into age andbirefringence, is preserved. Talc replaces pyroxene a rock with 40% inclusions, 5 to 10% of which are ul- to a limited extent and also rims and veins sapentinized tramafic xenoliths (central breccia phase). The inclusions grains. Interstitial spinels are also present in minoramounts. often form the cores of accretionary lapilli (Plate 55). Far- ther east the rock is a dark green, massive, unfoliated unit The interstitial spinels analysed on the energy dispersive withfewerclasts but containing abundant,randomly distrib- system of the scanning electron microscope are in the chro- uted phlogopite books and ultramafic xenoliths (eastern mite-hercynite solid solution series and can best be ~epre- massive phase). Bright red hematization is progressively sented by the formula (Fe, Mg) (Cr, A1)204 (Ijewliw, 1987). more evident towardthe top andcentre of the outcrop where The xenoliths may be broadly classified as spinel lher- entire mineral or xenolithic fragments may be hematized. zolites. Also preserved, although notas abundant, are€:met Pyrite is present as discrete grains in the groundmass andas lherzolites and glimmeritexenoliths (Hall et al., 1986,). rims surroundingclasts where it may, in turn, be enveloped The macrocryst population (0.5 to 5.0 mm in size:)con- by ragged, bright red hematite(red spotted phase). Contacts sists of completely serpentinized olivines, partially altered garnets, garnets withkelyphitic rims andphlogopites. They may beround, ovalor lath shaped in random orientation and TABLE 18 make up 10 to 20% of the rock volume. Garnets sf~owa CHEMICAL ANALYSIS moderate to high degreeof alteration or dissolution in reac- CROSSING CREEK KIMBERLITE tion with the matrix. None are enhedral. They are rounded

~~~ ~ and irregular in shape and surroundedby kelyphitic rims or __wr % 1 2 3 reaction coronas of opaque iron oxides (Ijewliw, 198711. The Si02 30.04 30.74 30.02 garnets arepyrope rich. Phlogopites are occasionally zoned, Ti02 1.28 1.45 1.29 1.44 with rims darker and morestrongly pleochroic than cores A1203 2.23 2.31 2.21 2.10 :::;I and often displayingreversepleochroism (Halletal., 1986). Fe203T 6.89 8.28 5.31 7.48 7.70 MnO 0.12 0.16 0.09 0.11 The phenocryst populationis comprised of completely MgO 25.03 27.72 23.54 27.75 23.840.151 serpentinized olivine, together with phlogopite and :;pinel CaO 13.48 9.78 14.94 9.55 14.21 (Plate 56). Phlogopite grains vary in size, are randomly ori- Na20 0.07 0.09 0.03 0.02 ented, square to rectangular in shape and relatively unal- K20 1.37 1.01 1.47 1.26 1.22 0.05I tered. Reddish brown translucent spinels are disseminated LO1 17.8715.3817.04 15.4 17.37 no5 0.99 1.06 1.03 0.99 in the groundmass and show magnetite reaction rims -S 0.14 0.23 0.09 0.12 (Ijewliw, 1987). The groundmassis composed ofca1ci:e and Total 98.68 98.22 97.88 98.35 serpentine with minor apatite and anatase. ppm Ni 1000 1000 10W 1300 X90 Cr 12941369 1398 1747 1728 co 60 56 54 70 55 Rb 56 40 53 57 54 Sr 1177 1073 1171 1452 14921 Ba 3237 2642 3497 2648 3442 Zr 292 322 301 313 367 Nb 187 207 200 199 %30 Y 18 22 21 21 La 134 157 126 132 197 Ce 258 300 239 266 363 Nd na nana na na Yb 2 1 3 0 .:-I sc 20.323.1 23.7 20 25.1 Ta 7 14 9 11 11 Th 18 19 24 18 41 iu 14 14 15 !" 196 196 208 2; j cu 731 54 50 51 4 All amlyss'8 b;vXRF, B.C. G.S.B.analytical laboraforv 1. .CX5-6 Kin .. 0.00 400.00 800.00 1200.00 1600.00 2. - CX57B Hemotire-spotred kimberlite: red-sparredphase: Cr ppm ~- 3. - CX5-8A Kimberlife, easrem massivephase: 4. - CX6-Dl Fine-grained crosscutting, inclusion-free dike; Figure 85. "Average" values from Wederhaland Maramatsu 1979. 5. - CX5.7Micaceouskimberlite, red-sparfedphase. Ni vs Cr plot, Cross kimberlite.

~~104 Geological Survey Itranch Ministry of Energy, Mines and Petroleum Resources~~

GEOCHEMISTRY GEOCHRONOLOGY TheCross diatreme is the only trne kimberlite so far Rubidium-strontiumdating of micaseparates has recognized in the province. It fits both the petrologic and yie,ded Pemo-T~assicages of 240 244 k,a for the geochemical definitions of a kimberlite (Figures 83 and84; Cross kimberlite (Grieve, 1982; Smith, 1983; F:all et al., Table 18 ). Although it appears to bequite a heterogeneous intrusion, analyzed were all ve~similar geochemi- 1986 ). Both the Cross kimherlite and its hostrocks are sig- cally. It is characterizedby low silica, high magnesium, high nificantly younger than other British Cohtmbia diatreme strontium and high nickel and chrome(Figure 85; Table 18). suites.

~~- Bulletin 88 105 ~- 106 Geological Survey Eranch engineering ceramics and superconductors(Roskill Infor- he 1 to 4 metres wide and over30 metres long. Mafic syenite mation Services, 1988). dikes in the area generally contain lower concentrations of Significant enrichment in rare-earth elements is re- rare earths than the pegmatites; local concentrations up to ported from five localities in British Columbia, the Aley 4.26% total rare earths have been found (Halleran and complex and Rock Canyon Creek, bothin the Rocky Monn- Russell, 1990). Very little work has been donein the IvIount tains; the Wicheeda Lake area along the Rocky Mountain Bisson area and preliminary results indicate some potential; Trench near Prince George;the Kechika River area in the this area might warrant further work in the future, particu- Cassiar Mountains; and the Mount Bisson area in the larly if the demand for cerium and lanthanum incream. Omineca Mountains.At Aley narrowdikes enriched in rare- The presence of these five highly anomalous occur- earth elements, and locally fluorite, cnt the altered sedi- rences indicates that British Columbia is highly prospwtive ments peripheral to the main complex. Samplescontaining for economic accumulations of carbonatite-related rare- in excess of 2.1% total rare-earth oxides are present. The earth elements. rare earths are contained in carbonate mineralssuch as bastnaesite, burbankite, cordylite and huanghoite (Miider, ZIRCONIUM 1987). These dikes are thin and sporadically developed and, although worthy ofnote, not of major economicinterest. Zirconium is strongly concentrated in some alkaline At Rock Canyon Creekmetasomatically a altered(feni- rocks andmay comprise upto 2%. The main zirconiummin- tized) zone rich in rare earths and fluorite, measuring ap- erals present inthese rocks arezircon, eudyialite (Na-Zr sili- proximately 1000 by 100 metres, has been identified. cate) and haddeleyite (ZrOz), with alkaline rocks beir,g the Samplescontaininginexcess of 2.7% total rare-earthoxides only known source of substantial amounts of haddele yite. (predominantly cerium and lanthanum oxides) have been The major application of zirconium is in four dries obtained from outcropsof this zone.The rare-earth fluoro- where it isused in mineral formas facing for molds for metal carbonate mineralshastuaesite and parisite, and gorceixite, casting. It is also used in refractories, nuclear powerappli- a phosphatemineral, have been identified. At RockCanyon cations and chemical processing equipment.Of increasing Creek, locally high rare-earth values at surface, the size of importance is the application of zirconium inadvanccd ce- the zone andthe lack of extensive work suggest that further ramics which have suchdiverse uses as heat-resistant tiles, work is warranted. sensors and automobileexhausts. The principal sources of zirconium are zircon recovered as a hyproducl. from tita- In the Wicheeda Lake area a series of alkaline rocks and haddeleyiteproduced as a copro- including carbonatites, syenites and leucitites are exposed. nium placer deposits duct fromapatite mining ofthe Palabora carhonatite, Sonth Work by TeckCorporation has indicated that one carhona- Africa and of niobium miningat Araxa and Pocosde C aldas tite plug locally contains in excess of 4% total rare-earth carhonatites in Brazil (Adam, 1985). elements and one trench, across part the carbonatite, exposed material grading 2.60% total rare earths over its 42- Zircon is a ubiquitous phase in carbonatitc: and metre length (Betmanis, 1988). These valnes are nepheline syenite gneiss complexes in BritishCo1umb.a and predominantly in light rare earths, in particular cerium and crystals often exceed 1 centimetre in length. The Aley com- lanthanum, however, the results are favourahle andthis area plex, Paradise Lake syenite, Verity carhonatite, Tjident might warrant further work in the future, particularly ifthe Mountain syenite and Lonnie andVergil complexes all con- demand for cerium and lanthanum increases. tain coarse zircon inexcess of 1%. In the Lonnie. and 'Jergil complexes, the syenitic rocks may contain 3 to '15% zircon In the Kechika River area, alkaline rocks consisting of locally. Although it is unlikely that any of these rocks could syenites, malignites, breccias and fenites are intermittently compete with placer deposits, it is possible that zircceium exposed along a northwest-trending zone in excess of 15 could he produced as a hyprodnctof niobium 0.r rare..earth kilometres in strike length. During a recent exploration pro- mining and should hetested for. gram, samplescontainingin excessof 3.77% total rare-earth oxides (mainly cerium snhgronp elements) werecollected from carhonatite dikes; other samples containing up to PHOSPHATES 1.13% Y203, 0.30% NdzO3, 0.11% Sm2O3 and 0.14% Ultrabasic alkaline igneous complexes commonly con- Dy2O3 were taken from phosphate-richsegregations, contain high concentrations of phosphate, largely in the fcrm of taining upto 19.3% P2O5, in a mylonitizedsyenitekrachyte themineralapatiteandapproximately 18%ofallphos&hates (Pel1 et al., 1990). Rare-earth elements and yttrium in the mined come from igneous complexes. Apatite: from car- Kechika River area are present mainly in monazite, xeno- bonatites is mined at Palabora, South Africa; Dorowa, Zim- time and other phosphate minerals. The size of this zone, babwe; the Kola Peninsula in the U.S.S.R.; and Araxa and lack of detailed work and presence of anomalous concen- JacupirangainBrazil (Currie, 1976a;Russell, 1987; Feman- trations of heavy rare-earth elements suggestthat additional des, 1989). Grades as low as 4% P2O5 are currently recov- work is warranted. ered. Approximately 90%of all the phosphatemined i:; used Light rare-earth elements, particularly cerium and lan- in the fertilizer industry; other uses include organicmd in- thanum, are concentrated in allanite pegmatites and allan- organic chemicals, soapsand detergents, pesticides, :nsec- ite-hearing mafic syenite dikes that are associated with large ticides, alloys, animal-food supplements, ceranics, fenite zones in the Mount Bissonarea. Some of the pegma- beverages, catalysts, motor lubricants, photographic mate- tites reportedly contain up to 14.5% total rare earths and can rials and dental cements.

~~108 Geological Survey 1:ranch ~ ~~~

~~Ministry of Energy, Mines and PetreResources~~

In British Columbia, all carbonatites contain some apa- 1989). The remotelocation of this body, howeve!; severely tite. The Aley complex and carbonatites in the Blue River limits its economic potential. area are more enriched in apatite than many of the other carbonatites, containing, on average, 5 to 15% apatite, with VERMICULITE P205 contents up to 11% (Tables 1 and9) and averaging3.5 to 5%. The Rencarbonatite also has an average1'20s content Vermiculite is a mineral which expan& whm heated. of approximately3.5%, with maximum values of 4.2% (Ta- It is formed from alteration of biotite or phlogopite andis a ble 12). Carbonatite dikes cutting ultramafic rocks of the Ice characteristic accessory in ultrabasic rocks associated with River complex locally contain np to 8% PzOs (Table 3). carbonatites. Vermiculite is present in minor amountsasso- Syenitic mylonites in the Kechikaarea contain small zones ciated with carbonatites in the Blue River area, but is not which assay as high as 19.3% P20s and haveapatite as one reported from other areas. The potential for vermi<:ulite pro- of the major rock-forming minerals.The contin.uity ofthese duction from carbonatites in British Columbia is :xtremely phosphate zones is unknown and it is unlikely that they limited. would be exploited for phosphate alone. MOLYBDENUM It has been estimated that the Aley complex may contain as much as 15 billion tonnes of 5% P2O5, while other Molybdenum is generally associated with granitic as carbonatites probably contain only a few million tonnes of opposed to syenitic rocks, but,in some caw, it may bepre- phosphate reserves (Butrenchnk, in preparation). Produc- sent in alkaline complexes (Currie, 1976a). In British Co- tion of phosphates from these carbonatites as a primary lumbia, the nepheline syenite gneisses associate1 with the commodity is unlikely in light of competition from sedi- Frenchman Cap domecommonly contain nlolybdenite and mentary deposits, but byproduct recoveryof apatite might the Mount Copeland showings thewere focns of r.ignificant prove feasible, particularly in the case of Aley, if niobium exploration and developmentwork inthe late 1960s (Fyles, were to be mined. 1970). Current economics,however, do natfavour exploi- tation of molybdenum from such deposits. NEPHELINE AND NEPHELINE SYENITE WOLLASTONITE Nepheline and nepheline syenite are of major impor- Wollastoniteis an important mineralfiller nscd primar- tance in the glass and ceramicsindustries due to their high ily in the paint and ceramics industries. It #:an b,: found in alumina contentin the presence of abundant sodium; these two main geological environments:contact .metarnorpbicor elements act as a flux which affects the rate and temperature metasomatic (skarn) deposits and in carbonatite!:, as a pri- of melting, the flnidity of the melt andthe physical proper- mary, magmatic mineral. Most world production comes ties of the finished product. Small amountsare also used in from contact deposits (Harben andBates, 1990). paints and as fillers in plastics. Canada is currently the larg- Wollastonite has not been recognized in any carbona- est free-world producer of nepheline syenite which is all tites in British Columbia; however, it is worth looking for quarried in the Blue Mountainregion of Ontario. in fntnre discoveries. Nepheline syenite occurs in large volumes in a number of areas of British Columbia; the Ice River complex, Bear- TITANIUM paw Ridge, Paradise Lake, Trident Mountain, the Perry Titanium-bearing minerals are present in a inumber of River area and Mount Copeland.With the exception of the the carbonatite and alkaline rock complexesin Rritish Co- latter, most are relatively inaccessible. TheMonntCopeland lumbia. Sphene,perovskite and ilmenite have all been rec- syenite gneisses, which arelocated 25 kilometres northwest ognized. As well, knopite, a rare-earth emiched variety of of Revelstoke, may be reached by oldmining roads. Onav- perovskite, has been reported from the Ice R.iver area erage they contain moreiron, manganese, calcium andpo- (Ellsworth and Walker, 1926).In most cases, these titanium tassium, and less sodium, silica and aluminumthan thoseat minerals are present in relatively low concent:ations; at Blue Mountain (Table 11; Currie, 1976a). In general, the Howard Creek, however, sphene is a rock-forming mineral Mount Copelandsyenites are medium to coarse grained and in a melteigite of limited spatial distribution. It is unlikely it was considered that many of the impurities (ferromagne- that titanium could be produced from any of th,:se wcur- sian minerals - in particular biotite) could potentially be rences. removed by crushing and magneticseparation techniques; however, beneficiation tests failed to produce a product with DIAMOND a low enough iron content to meet industry specifications (White, 1989). Some of the other syenites, such asthe Para- Diamonds were traditionally considered to be prcsent disesyeniteorthelargehodyonTridentMountain,arequite in economic concentrations in kimberlites oniy. Recent similar in composition to those being minecl in Ontario. studies have shown that they may also be recosered from Beneficiation tests run on samples from Trident Mountain lamproites, and they havealso been reported fro:n such di- indicate that this syenite is low in magnetic impurities, has verse rock typesas peridotites and even carbonaites. Only a high recovery rate of nonmagnetic materials and, there- one true kimberlite has been discoveredin Briti:;h Colum- fore, has good potential to produce a commercial-grade bia, the Cross diatreme, but no results of laboratoly research nepheline syenite product witha brightness of 85% (White, on mineral compositionor diamond recovery have beenre- _" Bulletin 88 109 ~

~~British Columbia "~~

Stevens, R.D., Delahio, R.N. and Lachance, G.R.(1982): Age De- sition of Three Basaltic MagmaTypes; in Kimberlites, Dia- terminations and Geological Shldies, K-AI Isotopic Ages, tremes and Diamonds: Their Geology, Petrology and Geo- Report 16; Geological Surveyof Canada, Paper 82-2. chemistry, American Geophysical Union,Procwdings ofthe Stewart, J.H. (1972): Initial Deposits in the Cordilleran Geosyn- Second International Kimherlite Conference, Volume 1, cline: Evidence of Late Precambrian (R my) Continental pages 300-312. Separation; GeologicalSociefyofAmerica,Bulletin,Volume Wheat, T.A. (1987): Advanced Ceramicsin Canada;Canadian In- 83, pages 1345-1360. stitute of Mining andMefaNurgy,Bulletin, Volume 80,Num- Stewart, J.H. and Poole, F.G.(1974): Lower Paleozoic and Upper- ber 900,pages 43-48. most Precambrian Miogeocline, Great Basin, Western Wheeler, J.O. (1962): Rogers Pass Maparea, British Col~mbia United States; in Tectonics and Sedimentation, Sociefy of and Alberta; Geological Survey of Canada, Map 43-1 962. Economic Paleontologists and Mineralogists,Special Puh- Wheeler, J.O. (1963): Rogers Pass Map-area, British Colmhia lication 22, pages 28-57. and Alberta;Geological Surveyof Canada, Pap62.32. Symons, D.T.A. and Lewchuk, M.T. (in press): Paleomagnetism Wheeler,J.O.(1965):BigBendMapArea,BritishColumhia;Geo- of the MississippianHP Pipeand the Western Marginof the logical Survey of Canada, Paper 64-32. North American Craton; American Geophysical Union, Monograph Series. Wheeler, J.O., Campbell, R.B., Reesor, J.E. and Mountjoy. E.W. (1972): Structural Style of the Southern Canadian C!ordil- Taylor, G.C. and Stott, D.F. (1979): Monkman Pass (931) Map lera; International Geological Congress, Excursion A-01- Area, British Columbia;GeologicalSurvey of Canada, Open xo1. File Report 630. White, G.P.E. (1 982): Notes on Carbonatites inCentral Briti ;h Co- Thompson,R.I.(1978):GeologicalMapsandSectionsoftheHalf- lumbia; in Geological Fieldwork1981, B.C. Ministry of En- way River Map Area, British Columbia (94B); Geological erg3 Mines and Pefroleum Resources,Paper 1!>82-1,pages Survey of Canada, Open File Report536. 68-69. Thompson, R.I., Mercier, E. and Roots, C.(1987) Extension and White, G.P.E. (1985): Further Notes on Carhonatims in C!entral its Influence onCanadian Cordilleran Passive-margin Evo- British Columbia;in Geological Fieldwork1984, B.C: Min- lution; in ContinentalExtensional Tectonics, Howard,M.P., istry of Energ3 Mines and Petroleum Resources, Paper Dewey, J.F. and Hancock, P.L., Editors, GeologicalSociety, 1985-1,pages 95-100. Special Publication 28, pages 409-417. White, G.V. (1989): Feldspar and Nepheline Syenite Potertial in Vaillancourt, P. and Payne, J.G. (1979): Diamond Drilling Report British Columbia;in Geological Fieldwork1988, B.C Min- on the LonnieRitch Claims, Manson Creek Area, Omineca istry of Energy, Mines and Petroleum Resources. Paper Mining Division; B. C. Ministry ofEnergy, Mines and Petro- 1989-1,pages 483-487. leum Resources, Assessment Report7515. Wooley, A.R. (1982): ADiscussion of Carhonatite Evoluticm and von Knorring, 0. and du Bois, C.G.B. (1961): Carbonatite Lava Nomenclature and the Generation of Sodic :md Potassic from Fort Portal Area in Western Uganda; Nature, Volume Fenites; Mineralogical Magazine,Volume 46,pages 13-17. 192, pages 1064-1065. Woyski, MS. (1980): Geology of the Mountain Pass Carbmatite Warhol, W.N. (1980): Molycorp's Mountain Pass Operations; in Complex - A Review; in Geology and MineralWeatk of the Geology and Mineral Wealthof the California Desert,South California Desert, South Coast Geological Society, pages Coast Geological Sociefy,pages 359-366. 367-377. Wedepohl, K.H. and Mnramatsn, Y. (1979): The Chemical Com- position of Kimberlites Compared withthe Average Compo-

-~ 124 Geological Branch Survey ported by industry. Microdiamonds have, however, report- have also been reportedfrom alkaline lamprophyre dikes in edly been recovered fromtwo of the lamprophyre diatremes Montana. in the Golden - Columbia Icefields area. One of the pipes Nepheline syenites are known from afew localities in reported to have yielded microdiamonds fromconcentrates B.C. (e&, Paradise Lake, Ice River, etc.). These areas have collected and processedat two different times, from differ- not been evaluated for their potential to contain gem corun- ent laboratories. Asignificant amountof additional research dum. Alkaline lamphrophyres are present in the Rcckies is necessary to establish if economic concentrations are pre- (e.g., Golden cluster) and couldalso be prospected fa: gem sent. corundum varieties. GEMSTONES Blue corundum crystals (star sapphires) up to 1 to 2 centimetres in size, have recently been discovered in the Corundum (sapphire, ruby) is a common accessory Slocan Valley withina syenitic phase of the Valballa Gneiss mineral in silica-undersaturated, alumina-rich rockssuch as Complex, part of the Passmore Dome. These gneisser also nepheline syenites and nepheline-feldspar pegmatites. In contain sphene and amphibole and, in outcrop, resemble the Bancroft area of Ontario,corundum occursin nepheline- fenites in the Blue River and Perry Riverareas (Z.D. Hora, bearing rocks and marginal zonesof nepheline syenite in- personal communication,1993). Fenites are widesprer.d, as- trusions at Blue Mountain and elsewhere. Nepheline sociated with carbonatites and syenite gneiss complexes syenites at Cabonga Reservoir, Quebec contain blue corun- within metamorphosed rocks or the Ominica Belt and dum crystals mantled by biotite (Currie, 1976a). Sapphires should be prospectedfor gem corundum.

~~_" 110 Geological Survey 3ranch Ministry ojEnergy, Mines and Pelruleurn Resources~~

~~SUMMARY AND CONCLUSIONS~~

CARBONATITESAND SYENITE are sill-like bodies with extensive fenitic aureolss. Work GNEISSES done to date indicates moderate enrichment in rare-earth elements, with or without niobium. Carbonatites andsyenite gneisses crop out inthreebelts There appears to be a relationship between depth of parallel to the Rocky Mountain Trench. Theintrusions in the emplacement, degreeof associated metasonratism and en- eastern Rocky and Cassiar Mountainbelt are middle Paleo- richment in economically interesting elements suchas nio- zoic, predominantly Devono-Mississippian in age, hosted bium or rare earths. All ofthese factors are prohabl y related by lower to middle Paleozoicstrata and therefore are rela- to the original volatile content of the magma.. The most fa- tively high-level intmsions. They can be large and elliptical vourable areas for additional exploration for these slements in shape and havesignificant alteration halos (e&, Aley car- would appear to bethose underlain by lower to middle Pa- bonatite), consist simply of metasomatic alteration zones leozoic strata of North American affinity. The western (e.& Rock Canyon Creek showing),or be extensive linear Rocky Mountains and someregions of the eastern 13mineca belts comprising numerous and lithologically varied sills, Belt, close to the Rocky Mountain Trench, have the best dikes and plugs (e.g. the Wicheeda Lake and Kechika River potential. Byproduct recoveryof apatite and zircon should showings). The carbonatites in the eastern belt can be sig- also be consideredwhen assessing the niobium or me-earth nificantly enriched in niobium, fluorine, yttrium and rare- potential of any prospects. earth elements. Commercial-grade nephelinesyenite could pcttentially The central belt lies within the Omineca Belt, immedi- be produced from the Trident Mountainsyenite, however, ately west ofthe Rocky Mountain Trench. The intrusions in current inaccessibility precludes immediateexploitation. If this belt are also Devono-Mississippian in age, hut are this area were everto become moreaccessible, through the hosted by Precambrian strata; they were not emplaced as development of good logging roads, the nepheline syenite high in the stratigraphic succession as those in the eastem potential of this body would warrant serious exar.lination. belt. The carbonatites in the Omineca Mountainsare thin, Other compositionallysimilarsyenites are presentin British discontinuous, sill-like intrusions generally with narrow Columbia, but are also in remote locations and remain un- fenite alteration halos. With one exception(the Mount Bis- tested. son intrusions), they are notas enriched in niobium,fluorine or rare-earth elements as their eastern counterparts. KIMBERLJTES, LAMPROPHYRES AND The western belt, also within the Omineca Mountains, OTHER ULTRABASIC DIATREMES comprises intrusive and extrusive carbonatites and Ultrabasic diatremes have been recognizedin five areas nepheline syenite gneisses hosted by the autochthonous of British Columbia; the Kechika River and OspikaRiver cover sequence of the Frenchman Cap gneiss dome. The areas of northern British Columbia, the Goldan, Bull River enclosing metasedimentary rocks of are uncertain age, how- -Elk River and Elkford areas of the Kcatenays. Iri the Os- ever, recent studies suggest that they mayhave been depos- pika River area north of Mackenzie, and in the Columbia ited in a period which spanslate Precambrianto Eocambrian Icefields area north of Golden (Figure Z), the diatrwnes are time (HOy and Godwin, 1988). A single radiometric date, characterized by macrocryst-rich breccias and dikes. The obtained on one of the alkaline intrusive bodies (Mount macrocryst population consists of clinopyroxene, phlo- Copeland syenite) which occurs near the base of the man- spinel and olivine, tling gneiss succession, indicates an age of emplacement of gopite, green diopside, with either pyroxene or phlogopite as the most abundantphase. In some circa 770 Ma for that intrusion (Okulitch et al., 1.981).This cases, microphenocrystic feldspars are present :,.nsmall gives a minimum age for the basal part of the succession. amounts. These rocks aretentatively classifi,ed as lampro- Much higher in the mantling gneiss stratigraphy, overlying phyres; the HPpipe in the Golden area and the Ospika pipe the carbonatitehorizons, a strataboundlead-zincdeposit has can he classified as aillikites, which are members cf the ul- yielded an Eocamhrian to early Cambrian lead-lead date. tramafic lamprophyreclan based on their modal mineralogy This suggests that the highest stratigraphic levels of the and, to a lesser extent, the chemistry. The other ultrabasic mantling gneiss succession are Early Cambrian and the in- intmsions in the Golden area are more difficltlt to 'classify; tervening stratigraphy was deposited between Late Protero- they appear to be most similar to amphibole-free alkaline zoic and early Paleozoic time. The extrusive carhonatites lamprophyres.In all cases the breccia pipes commonly con- are located relatively high in the mantling gneiss stratigra- tain multiple phases of intrusion characterized by variable phy, approximately 100 metres below the lead4nc layer proportions of xenoliths, macrocrysts and accretionary and, like the lead-zinc deposit, are probably Eocambrian in lapilli or spherical structules. The breccia matrix in some age. cases is clearly magmatic. These pipes are characteristic of The carbonatites in the western belt comprise high- the diatreme facies material, as described from kilnberlite level intrusions and extrusives. The carbonatite intrusions pipes and/or hypabysal-facies (Clement and Reid, 1986).

~~Bullelin 88 111 . ~~~~

~~Brirish Columbia “ ~~~~~~

They formed from extremely volatile-rich magmas, so rich, diatreme-facies tufflsitic breccias. Some pipes bneached the in some cases, that as they reached the surface and vesicu- paleosurface andthe upper parts of the crater zone contain lated, the magmatic phase exsolved fromthe volatiles and beddedepiclasticorpyroclasticrocks.Anumhert~fthe])ipes actually formed the ‘bubbles’, as indicated by the spherical in the Bull River- Elk Riverarea intrude Ordovician-Silu- stmctures (or globular segregations) and armoured xeno- rian Beaverfoot carbonate rocks andcontain bedded cl’ater- liths. At Lens Mountain, Mons Creek and Valenciennes facies material which is unconformably overlain b., the River sandy tuffisitic or gas-stream breccias, with an insig- basal Devonianunit (MiddleDevonian) suggestinganl3arly nificant recognizable igneous component, arealso present. Devonian age of emplacement of approximately 4oC Ma. Rubidium-strontium and potassium-argon dates of Other pipes and flows apparently underlie and predate the 3381r3 and 323f10 Ma havebeen obtained from phlogopite Beaverfoot Formation, but cut middleSilurian rocks and, separates from the Ospika pipe. These dates indicate that therefore, must be approximately 455 Ma in. age. The emplacement occurred in Devono-Mississippiantime, as is Kechika pipe is also hosted by Ordovician to Silnrian litrata the case for the most of the carbonatites in the eastern and and associatedwith beddedtuffs whichmust be of the Same central belts. Aillikites and alnoites arenoted for their affili- age as the host strata (possibly circa 450 Ma.). ation with carbonatites (Rock, 1986). Pipes and dikes from The craters containing these breccias are envisaged to two areas north of Golden have also been dated. Inthat area, have a ‘champagne glass’ structure, similar to that of lam- most of the diatremes were emplaced slightly earlier, in proite or basaltic craters, with no extensively developedrmt Early Devonian time (circa 400 Ma). Zircons from ultra- zone. The breccias are commonly associated with cro5 scut- basic rocks in the Mons Creekarea yielded concordantlead- ting porphyritic dikes and flows, characterized by the pres- lead ages of 469 Ma; if these zircons are not xenocrystic, it ence of phenocrystic olivine and titanaugite, with ahwdaut may indicate that there was a third period of emplacement feldspar (plagioclaseorpotassiumfeldspar),titanaugite and in the Late Ordovicianto Early Silurian. opaque oxide microphenocrystsin a fine-grained ground- Intrusions in the Bull River and Kechikaareas are dis- mass. These rocks are extremelydifficult to classify: they tinctly different than those in the Golden or Ospika areas. are ultrabasic, and locally quite potassic, feldspar-bearing They are characterized by chaotic breccias containing abun- rocks that can contain vesiculated glass lapilli and are gen- dant vesiculated glass lapilli, juvenile lapilli and rare altered erally devoid of hydrous mafic minerals andfeldspathoids. olivine, altered pyroxene, feldspars and chromian spinel They may have originated in volatile-enriched systems, but macrocrysts and by the absence of primary micas. The ma- not to the extent of the previous diatremes; as ihey n:ared trix of these breccias is not magmatic; they are crater and the surface the volatiles exsolved fromthe maglna and not

Figure 86. Structural positionof diaEemes, B - Bush River;C -Lens Mountain; D - Mons Creek;E - Valenciennes River ;P HP pipe; G - Shatch Mountain;H - Russell Peak; I - Blackfoot; J - Quinn Creek; K - Summer :L - Crossing Creek,Geology modified from Wheeler (1963),Wheeleretal., ( 1972),Leech (1979), Price(1981).

~~ 112 Geological Survey haranch Ministry of Energy, Mines and Petrnleum Resourres the reverse. In some cases they maybe tentatively classified North America, it isunlikely that significant concentrations as limburgites, in others they appear to be most similar to of diamonds canbe found in nonkimberlitic rock!: originat- members of the alkaline basalt family, but gmerally are ing so far from the stable craton; however, the we.;tern con- more basic than typical alkaline basalts which suggests that tinental margin at the time of diatreme emplacement was they are verging towardsnephelinites. probably significantly more complexthan theone proposed The last distinct rock typeis represented by one exam- in Haggerty’s model for South Africa. The locat ion of the ple, the Cross kimberlite, located at Crossing Creek, nortb westem edgeof the continental mass at that time is unknown of Elkford. As the nameimplies, it is a true kimberlite, the and the depth to the lithosphere-asthenosphere bcandary is only one so far recognized in the province. It is apparently also uncertain, therefore, the proposed constraints on dia- a deeply eroded piperemnant and contains two generations mond genesis may be not directly applicable. of olivine, phlogopite, pyroxene, garnet and spinel megacrysts as well as garnet and spinel lhemlite nodules TECTONIC IMPLICATIONS (Hall etal., 1986). Rubidium-strontiumisotopic ratios indicate that the pipe was emplaced in Permo-Tiiassic time, The emplacement of carbonatites, kimberlites and circa 245 Ma (Grieve, 1982; Hall etal., 1986). other alkaline rocks in the Canadian Cordillera appears to be related, in part, to extension andrifting along tte western At this point it is difficult to completely assCss the depth continental margin that produced and deepened the basin of origin and diamondpotential of theserocks. The Crossing into which the miogeoclinal succession ‘was t.eposited. Creek kimberlite apparently originated deep in the mantle, Sedimentological and stratigraphic evidence inc.icate that it contains abundant pyropegarnets and has sampled mantle the western continental margin was tectonically active lithologies including garnet lherzolites. This suggests that it throughout much of the Proterozoic and Paleozc,ic eras. It may have originated at depths generally considered suffi- does not appearto have behaved entirely in a passive man- cient to be in the diamond field; however, diamond genesis ner and therefore may not be strictly analogous lo the pre- apparently depends on oxygenfugacity as well as pressure sent day Atlantic margin, as earlier workers proposed and depthof origin alone is not sufficient to predict thedia- (Stewart, 1972; Stewart andPoole, 1974); rather it appears mond potential of a pipe (Haggerty, 1986). The pipes inthe that several superimposed ‘passive margin-type’ :;equences other arms of British Columbia do not appear to have origi- are present as a result of periodic extensional activity (Pell nated as deep in the mantle as the Crossing Creekkimberlite. and Simony, 1987; Thompson et al., 1987). During these They contain no good evidence of deep mantle xenoliths; periods of extension, deep faults and fractures in the crust the xenolith and xenocryst populationsare generally con- may have released pressure and triggered partial melting, fined to crustal material: rare eclogites, spinel. lberzolites, 19). chrome spinels and very rare pyrope garnets (Northcote, whichultimatelyresultedinalkalinemagmatism(Tab1e 1983a, 1983b). This suggests an origin in the spinel lher- The earliest event recordedby alkaline activi:y in west- zolite field of the uppermantle, which is generally consid- ern Canada is represented by the Mount Copelandsyenite ered to be at pressures below those required for diamond of Late Proterozoic in age (circa 770 to 750 Ma); it may formation. Microdiamonds reportedly found in two of the record extension or rifting of the North Ame:rican (cratonand pipes in the Golden swarm suggest that these pipes may the initiation of the Late Proterozoic Windermere basin. Di- have sampled the uppermost levels of the diamond field. abase dikes and sills of similar age (770 Ma) in northern Canada also record extension preceding Windemleredepo- When comparedto current models, it appears that the probability of British Columbia diatremescontaining eco- sition (Armstrong et al., 1982). Slightly younger datas of 728 and 741 Ma nomic concentrations of diamonds is low. From craton to (U-Pb, zircons) have been obtained from margin, a sequence of kimberlite with diamond, kimberlite granitic gneisses which appear to be basemen1 for Win- dermere Supergroupstrata in north-central and central Brit- without diamond(e&, Cross) and diamond-free ultrabasic ish Columbia ( Parrish and Armstrong, 1983;Evznchick ef diatremes (nonkimberlitic) is commonly proposed (Hag- gerty, 1986). In anattempt to establish the original positions al., 1984). This implies that rifting began as early as 770 Ma in some areas, but that the event spanned a pericd of time of the diatremes relative to the North Americancontinent, and, locally,Windermere sedimentationdid not beginuntil theirpositions have beenprojectedontocross-sections (Fig- after 730 Ma. ure 86). If these sections were restored to predeformational configurations, the pipes contained in the most westerly Sedimentary loading and synsedimentaryfaulting (Lis thrust sheet would have been the farthest outboard. The and Price, 1976; Eisbacher, 1981; Root, 1.983; Bond and Cross kimberlite is in the Bourgean thrust sheet and is the Kominz, 1984; Devlin and Bond, 1984) accoun:ed for the easternmost of the diatremes. The ultrabasic diatremes in deepening of the basin and the continuation of deposition the Bull Riverarea are carried by the Bull River- Gypsum into the early Paleozoic. Minor extensional activity is also fault (Figure 86), which is west of the Bourgeau thrust. As indicated by the presence of acid to basic volcanic andin- the faults are traced to tbe north, the Bull River- Gypsum trusive rocks throughoutthe Hadrynian to early Paleozoic thrust apparently dies out and the displacement is accom- sedimentary wedge (Simony and Wind, 1970; Raeside and modatcdby the Simpsons Passthrust. The alnoitic rocks and Simony, 1983; Pell and Simony, 1987; Sevigny, 1987). alkaline lamprophyres north of Golden are carried on a Extrusion oftheMount Grace carbonatiteandintrusion thrust (the Mons fault) which lies west of the Simpsons Pass of shallow-level carbonatites, accompanied by :he forma- thrust and apparently originated the farthest outboard of the tion of extensive zones of fenitization, probably occurred in continent. If Haggerty’s model is applicable to western Eocambrian to Early Cambrian time (Htiy and Godwin,

~~Bulletin 88 113~~

~~Minisfry of Eneqy, Mines and Pet,%l Resources~~

1988). These rocks occurin a relatively thin cover-succes- ported from the mid-Devonian to early M:ississippian se- sion above core gneisses of the Frenchman Cap dome, quence in the northern and central Canadian 'Cordillera which suggests that the dome may reflect a tectonic high in (Gordey, 1981; Mortensen, 1982; Gordey et al.. 1987) as late Precambrian to Early Cambrian time. Emplacement of well as in the southern Canadian Cordil.lera :Wheeler, the alkalic rocks may have coincidedwith foundering of an 1965). extensive Lower Cambrianplatform to the east. This period The Devono-Mississippian extension was synchronous is also interpreted by many workers as the time of the rift- with, or slightly postdated, compression to the south that to-drift transition along the western continental margin was associated withthe Antlerorogeny. Devono- Mississip- (Bond and Kominz, 1984; Devlin and Bond, 1984; pian granites and granitic gneisses have also been docu- Thompson et al., 1987). In the southwestern United States, mented in the Canadian Cordillera and Alaska (Okulitchet carbonatites of Eocambriau to Early Cambrian age are re- ab, 1975; Dillonefal., 1980;Montgomery, 1985: Okulitch, ported from a numberof localities (Figure 87); for example, 1985;Mortensen 1986;Mortensenetal.,19117).Theserocks the McClure Mountain carbonatite-alkalic complex, the crop out west of the alkaline intrusions and are believed to Gem Park and the Iron Hill carbonatite complexes in Cob have intruded near the western edge of the Paleozoic Cor- rado and the Lobo Hills syenite and carbonatite in New dilleran miogeocline (Okulitch er al., 1975). Aso during Mexico (Fenton and Faure, 1970; Olson et al., 1.977; Loring Devono-Mississippian time,a mixed volcanic and sedirnen- and Armstrong, 1980; Annbrustmacher, 1984;McLemore, tary sequence, termedthe Eagle Bay assemEdage, wasform- 1984; 1987;). Although these intrusions are structurally ining offthe western contintental margin; these rocks record board of the Mount Grace carbonatite, their emplacement a change from anisland arc environment at the base of the may be related to the same large-scale extensional tectonic sequence, wherecalcalkaline volcanics wen: forning above event. a subductingplate, to a rift environmentin wbicb alkaline Anumberofperiods ofPaleozoicextension areinferred volcanism and sedimentation took place 6:Schi;lrizza and along the western continental margin; however, additional Preto, 1987). dating is necessary to clearly define these periods and elimi- nate possibilities of overlap. The earliest event is Late Or- Thesedatasuggestthatacomplextectonicre,:imemust have pertained at the end of the Devonian andthat it was not dovician to Ordovician-Silurianin age (circa 450 Ma) and is recorded by the emplacement of some ultra'basic diatre- simply a timeof extension. A more complexmollel is necessary to explain westerly sources for Devono-:Mississip- mes and alkaline lamprophyres in the southern Rocky Mountains and the Golden area of British Columbia. The pian miogeoclinal sediments, obduction a1 the latitude of Bearpaw Ridge sodalite syenite (eastern belt, Figure 1)may present-day northern California and southern OIegon, and also prove to be Ordovician to Early Silurian in age as was emplacement of granites in southern British Colnmbia, the Cariboo and Alaskaat approximately the same timeas ex- originally proposed by Taylor and Stott (1980). who believed it to be a subvolcanic plutonrelated to alkaline basalt tension and alkaline intrusion were taking placl: near the flows in the Silurian Nonda Formation. Syenites, trachytes, eastern margin ofthe Canadian Cordilleran miog:ocline. A carbonatites and ultrabasic diatremes and tuffs in the sequence of events may have occurred which culminatedin the development of an incipient continental back:arc rift at Kechika area may also be of a similar age. Carbonatites of a complex, attenuated margin (see Struik, 1987). as local- approximatelythe same age are foundin the Lemitar Moun- ized obduction (and possibly subduction) occurred to the tains of New Mexico (McLemore,1987). south and outboard. Subduction probablyresulted inpartial A secondperiod of alkaline igneous activi.ty along the melting and genesis of granite and calcalkaline volcanic western margin of North America occurred in Early De- rocks; this compressional regime was ap;parently super- vonian time (circa 400 to 410 Ma). Most of the ultrabasic ceded by an extensional regime. Alternatively, e:ctensional and alkaline lamprophyres in the Golden area and somenl- basins may have resulted from strike-slip faulting: outboard trabasic diatremes in southern British Colnmbia were em- of the preserved marginof the miogeocline, as pr,>posed by placed at this time. Diatreme breccias in the Yukon Territory Eisbacher (1983) and Gordey et al. (1987:1; however, this (e.g., Mountain diatreme, R.L. Armstrong, personal com- scenario does notexplain the intrusion of g:raniter. munication, 1988)are of the same age. In a more continental setting (Figure 87). EarlyDevonian kimherlites are reported The last Paleozoic extensional event is inferred liom from thecolorado-WyomingState-Linedistrict (McCallum the presence of Permo-Triassic kimberlite in the Rocky et al., 1975; McCallum and Marbarak,1976; Hausel et al., Mountains. Although only one exampleis known, it ispos- 1979). sible that other alkaline intrusions of simihu age exist and A third Paleozoic extensional event at the end of the that other evidence for extension may be discovered. As Devonian (circa 350 to 370 Ma)resulted in the intrusion of with theprevious event, Permo-Triassic extmsion occurred carbonatites into the miogeoclinal successionin the Fore- approximately synchronously with compression in the land and Omineca belts. Aillikite diatremes (ultramafic lam- southern Cordillera (Sonomau orogeny). prophyres) and dikes in the Ospika River area were also In Late Jurassic to Early Tertiary time, orogmesis oc- emplaced at this time. The tectonic instability resulting from curred when a compressional regimewas established on the this major Devono-Mississippianextensional event is also Pacific margin whilerifting and the opening: ofthe Atlantic evident in the stratigraphic record (Thompson et al., 1987); took place on the opposite side of the continent. During OIO- volcanic rocks (someperalkaline in composition), synsedi- genesis the continental margin prism was telascopedand the mentary block faults and chert-pebble conglomerates arere- alkaline igneous rocks were deformed,metamorphosed and

Bulletin 88 115 . LEGEND ; Tom LEGEND WILLIAM HENRYBAY I: MOUNTAIN DIATREME i SALMON BAY KECHIKA PIPE ! KECHIKA , ALEY i LONNIE F MOUNT BISSON 1 WICHEEOA LAKE i BEARPAW RIDGE IO BLUE RIVER AREA I I TRiOENT MOUNTAIN I2 PERRY RIVER-MOUNT GRACE I3 MOUNT COPELAND 14 THREE VALLEY GAP I5 ICE RIVER 16 ROCK CANYON CREEK 17 RAINEY CREEK I8 BEARPAW MOUNTAINS I9 RAVALLliLEMHl COUNTIES !O IRON HILL. GUNNISON COUNTl !l WET MOUNTAINS CUSTER AND FREMONT COUNTIES !Z GEM PARK/MsLURE MOUNTAiN !3 MONTELARGO 24 LEMITAR MOUNTAINS !5 MOUNTAIN PASS

SYMBOLS SYMBOLS 19+ 0 Age unknown Age unknown v Tertiary (-50 & -30Ma) 01 Tsriiary (Eocans) -50Mo X Oevono-Mirrirrlplon -350Ha UpperCretocsour + -90-95Ma # Permo-Trioaric -245Mo X Dewno-Uisriraippian UNITED 0 Ordorician-Silurian -450Ma OCEAN 350-375Ma A EarlyDevonian -4OOMo STATES 0 Ordoviclon-Silurlon -45OMa t Placerdiamond Ioc~lity I LowerCambrion-EoCombrlon :D) MlsrodlomondIoEOlity 520-58OMo t Lobproterorols -770Mo A Mid-Pmlerozolc 1400-15OOM

~~23 MCordllleron front ,---Western limit of the .... miageoc1ino1rtrato ......~~

MEXICO 0." :i KILOMFTRLI \ 1 I :! Minisfry of Energy, Mines and PetreResoumes transported eastwards in thrust sheets. Their present distr- Cordillera, however, young calcalkaline lamprophyres, bution near the Rocky MountainTrench is due to original strongly alkaline basalts and miaskitic syenite complexes location along a rifted continental margin, not to later tec- such as KrugerMountain, Copper Mountainand theCoryel1 tonics. No syn or postorogenic carbonatites or alkaline nl- intrusions are present. tramafic diatremes have been discovered in the Canadian

~~Bulletin 88 I17 British Columbia "~~

~~118 Geological S~rrvey3ranch Ministry of Enevy, Mines andPetlw Resources~~

~~REFERENCES~~

Aaquist, B.E. (1981): Report on Diamond Drilling on the AZ-1 Barlow, A.E. (1902): Nepheline Rocks of Ice River, British Co- Claim Group,Kamloops Mining Division;B.C. Ministry of lumbia; Ottawa Naturalist, June 1902, page 70. Energy,MinesandPetroleumResources,Asse!;smentReport Bending, D. (1978): Fluorite Claims, Golden :Minin,: Division; 9923. B.C. Ministry of Energy, Mines and Petndeum Resources, Aaquist, B.E. (1982a): Assessment Report on Verity First I, 2, 3 Assessment Report 6978. Claims, Blue River, British Columbia:B.C. Ministry of En- Betmanis, A.I. (1987): Report on Geological, Geochemical and eqy, Mines and Petroleum Resources, Assessment Report Magnetometer Surveys on the Prince and George Groups, 10955. Carib00 Mining Division; B.C. Ministry of Encrgy, Mines Aaquist, B.E. (1982b): BlueRiver Carbonatites, BritishColumbia, and Petroleum Resources,Assessment Report1.7 944. Final Report 1981;B.C. Ministry of Energy, Mines andPe- troleum Resources,Assessment Report 10 274. Betmanis,A.I.(1988):SamplingEvaluation,l?G.NiobiumProject (Prince and George Groups); unpublished repixi for Teck Aaquist, B.E. (1982~):Assessment Report, Blue River Carbona- Explorations Limited. tites, 1982; B.C. Ministry of Energy, Mines and Petroleum Bond, G.C. and Kominz, M.A. (1984): Constnlction Tectonic Resources, Assessment Report 11 130. of Subsidence Curves for the Early Paleozoic Miogeocline, Adams, W.T. (1985): Zirconium and Hafnium; in Mineral Facts Southern Canadian Rocky Mountains: Implications for Suh- and Problems, 1985 Edition, United States Department of sidence Mechanisms, Ageof Breakup and CNS~;.~Thinning; the Interior, Bureau ofMines, Bulletin 675, pages 941-956. Geological Society ofAmerica,Bulletin 95, pag:s 155-173. Ahroon, T.A. (1979): Airborne Helicopter Magnetometer-Spec- Bonney, T.G. (1902): On a Sodalite Syenite (Ditroit:) from Ice trometer Survey on the BlueRiver Carbonatite Project, Brit- River, British Columbia; Geological Ma(:azine Volume 9, ishCo1umbia;B.C. MinistryofEnergy, MinesandPetroleum pages 199-213. Resources, Assessment Report 8216. Brown, R.L. (1980): Frenchman Cap Dome, Slmswap Complex, Ahroon,T.A. (1980): GeologicalReporton theBlueRiverProject, British Columbia; in Current Research, PaR A, Geological British Columbia: B.C. Ministry of Energy, Mines and Pe- Survey of Canada, Paper XO-IA, pages 45-51. troleum Resources,Assessment Report 9566. Butrenchnk, S.B. (in preparation): Phosphate Deposits in British Allan, J.A. (1911): Geology of the Ice River District, British Co- Columbia: B.C. Ministry of Energy, Mims and Petroleum lumbia; Geological Survey of Canada, Summary Report, Resouzes. 1910, pages 135-144. Campbell, EA. (1961): Differentiation Trends: in th: Ice River Allan, J.A. (1914): Geologyof theFieldMap-area, 13ritishColum- Complex, British Columbia; American Journal of Science, bia and Alberta:Geological Survey of Canada, Memoir 55. Volume 259, pages 173-180. Alonis, E. (1979):Fluorite Claims, Golden Mining Division:B.C. Clement, C.R. and Reid, A.M. (1986): The Origin of Kimberlite . MinistpojEnergy, MinesandPetroleumResources,Assess- Pipes: An InterpretationBased on a Synthesis of Geological ment Report7830. Features Displayed by South AfricanOccurrences; Geologi- Armbrustmacher, T.J. (1979): Replacement and Primary Mag- cal Society of Australia,4th International Kimlmlite Con- matic Carhonatites fromthe Wet Mountains Area, Fremont ference, pages 167-169. and Custer Counties,Colorado; Economic Geology, Volume Clement, C.R., Skinner, E.W.M. and Scon-Snuth, B.H. (1984): 74, pages 888-901. Kimberlite Redefined; Journal of Geology, Volume 92, Armbrustmacher,T.J. (1984):AIkalineRockCompIexesinthe Wet pages 223-228. Mountains Area, Custer and Fremont Counlies, Colorado; Cunningham, L.D. (1985a): Columbium; in Mineral Facts and UnitedStates Geological Survey,Professional Paper 1269. Problems, United States Departmentof Interioi; Bureau of Armbrnstmacher, T.J., Brownfield, I.K. and Osmonson, L.E. Mines, Bulletin 675, pages 185-196. (1979): Multiple Carbonatite Dike at McClure Gulch, Wet Cunningham, L.D. (1985b): Tantalum:in Mineral Fac's and Prob- Mountains Alkaline Province, Fremont County, Colorado; lems, United Stares Department ojrnnlerior, Bureau of Mountain Geologist, Volume 16, Number 2, pages 37-45. Mines, Bulletin 675, pages 811-822. Armstrong, J.E., Hoadley, J.W., Muller, J.E. and Tipper, H.W. (1969): Geology, McLeod Lake, British Columbia (933); Currie, K.L. (1975): The Geology and Petrologyof the Ice River Geological Survey of Canada,Map 1204A. Alkaline Complex; Geological Survey 01 Canada, Memoir 245.65 pages. Armstrong,R.L.,Eisbacher,G.H.andEvans,P.D.(1982):Ageand Stratigraphic-Tectonic Significance of Proterozoic Diabase Cunie, K.L. (1976a): The Alkaline Rocksof Cmada: Geological Sheets, Mackenzie Mountains, Northwestern Canada; Ca- Survey of Canada, Memoir 239. nadian Journal of Earth Sciences, Volume '19, pages 316- Cnrrie, K.L. (1976b): Notes on the Petrology of Nepheline 323. Gneisses near Mount Copeland, BritishColumbia; Geologi- Baadsgaard, H., Folinsbee, R.E. and Lipson,J. (1961): Potassium- cal Survey of Canada, Memoir 265. ArgonDatesofBiotitesfromCordilleranGranites;Geologi- Dawson, G.M. (1885): Preliminary Report on the Fhysical and cal Society ofAmerica,Bulletin, Volume 72, pages 689-702. Geological Featuresof that Portion of the Rockit Mountains

- Bulletin 88 119 between 49"M)' and 51'30'; Geological Surveyof Canada, Forbes, R.B., Kline, J.P. and Clough, A.H. (1987): A Preliminary Annual Report, Volume 1, Part B. EvalnationofAlluvialDiamondsDiscoveredinPlacerGrav- els of Crooked Creek, Circle District, Alas.ka; Sflfeaf Dawson, J.B. (1962): Sodium Carbonate Lavas from Oldoinyo Alaska. Deparfmenfof Natural Resources,Repxl of [nves- Lengai, Tanganyika; Nature, Volume 195, pages 1075-1076. tigation, 87-1. Dawson, J.B. (1964):Carbonate Tuff Cones in Northern Tangan- Fox, M. (1987): Geological and Geochemical Repo~t,RAI 1-9, yika; Geological Magazine,Volume 101, pages 129.137. REE 1-8 and REO 1 and 2 Mineral Claims; c7oIdert Rule Dawson, J.B. (1980): Kimberlites and their Xenoliths; Springer- Resources Lfd.,unpublished report. Vedas, 250 pages. Fyles, J.T. (1959): Geological Reconnaissance, Columbia River; Deans, T. and Roberts, W. (1984): Carbonatitic Tuffs and Lava B.C. Ministry of Energy, Mines and Petroleum Rescurces, Clasts ofthe Tinderet Foothills, Western Kenya:A Study of open file report, pages 27-29. Calcified Natra'arbonatites;Journal of the Geolo8ical So- Fyles, J.T. (1960): Geological Reconnaissance of the Columbia ciery of London, Volume 141, pages 563-580. RiverbetweenBlueWaterCreekandMicaCreek;B.C.Min- Deans, T., Snelling, N.J. and Rapson, J.R. (1966): StrontiumIso- isfryofEnergy, MinesandPetroleumResources,AnnlalRe- topes and Trace Elements in Carbonatites and Limestones port 1959, pages 103-104. from Ice River, British Columbia; Nafure, Volume 210, Fyles, J.T. (1970): The JordanRiver Area,near Revelstoke, British pages 290-291. Columbia; E.C. Minisfry of Eneqy, Mines and Petroleum Devlin, W.1. and Bond, G.C. (1984): Syn-depositional Tectonism Resources, Bulletin 57. Related to Continental Breakup in the Hamill Group, North- Gabrielse, H. (1962): Kechika, B.C.; Geological Suivey o:Can- ern Selkirk Mountains, British Columbia (abstract); Geo- ada, Map 42-1962. logical Associalion of Canada, Program with Abstracts 9, Godwin,C.I.andPrice,B.J.(1987):GeologyoftheMountainDia- 57. treme Kimberlite,North-central Mackenzie Mountains, Dis- Dickinson, W.R. (1977): Paleozoic Plate Tectonics andthe Evolu- trict of Mackenzie, Northwest Territories; in Mineral tion of the Cordilleran Continental Margin;in Paleozoic Pa- Deposits of the Northern Cordillera, Morin, J.A., Editor,Ca- leogeography of the Western United States, Stewart, J.H., nadian Institufeof Mining and Mefallurgy,Special blume Stevens, C.H. and Fritsche, A.E., Editors, Society of Eco- 37, pages 298-310. nomic Paleonfologisfs and Mineralogisfs,Pacific Coast Pa- Gordey, S.P. (1981): Stratigraphy, Structure and Tectonic l~volu- leogeography Symposium l, Pacific Section, pages tion of the Southern Pelly Mountains in the Indigc, Lake 137-155. Area, Yukon Territory; Geological Surveyof Canada,Mem- Dillon,J.T.,Pessel,G.H.,Chen,J.H.andVeach,N.C. (1980):Mid- oir 318.44 pages. dle Paleozoic Magmatism and Orogenesis in thc Brooks Gordey, S.P., Abbott, J.G.,Tempelman-Kluit,D. andljabrielse, H. Range, Alaska;Geology, Volume 8, pages 338-343. (1987): 'Antler' Clastics in the Canadian Corcillera; Geol- Dummea, H., Fipke, C. and Blusson,S.L. (1985): Diamondiferous ogy, Volume 15, pages 103-107. Diatremes of Eastern British Columbia;Canadian Instirule Graf, C.(1981): Geochemical Report, CandyClaim, 0oIdenMin. of Mining and Metallurgy, Bulletin, Abstract, Volume 78, ing Division, NTS 821/3B; B.C. Ministry of Energy, Mines pages 56-58. and Petroleum Resources,Assessment Report 9960. Eishacher, G.H. (1981): Sedimentary Tectonics and Glacial Re- Graf, C. (1985): Geological Report on the DP 1,2, :3 and Candy cord inthe Windermere Supergroup, Mackenzie Mountains, Claims, Rare-earth Element- Fluorite Prospect;B.C. Minis-. Northwestern Canada;Geological Survey of Canada, Paper try of Energy, Mines and Petroleum Resources,Assetzsment 80-27. Report 14 677. Eisbacher, G.H. (1983): Devonian-Mississippian Sinistral Grieve, D.A. (1981): Diatreme Breccias in the Southern Rocky Transcurrent Faultingalong the Cratonic Marginof Western Mountains (82'3 andJ); in GeologicalFieldwork 1980,B.C. North America: A Hypothesis; Geology, Volume 11, pages Ministry of Energy, Mines and Petroleum Resources;Paper 7-10. 1981-1,pages 96-103. Ellsworth, H.V. and Walker, J.F. (1926): Kuopite and Magnetite Grieve, D.A. (1982): Petrology and Chemistryof the: Cros:; Kim.. Occurrence, Moose Creek, Southeastern British Columbia; berlite (8210);in Geology in British Columbia,1977-1981, in Summary Report, 1925, Part A; Geological Survey of B.C. Ministry of Energy, Mines and Petroleum Resources, Canada, pages 230-233. pages 34-41. Evenchick, C.A., Parrish, R.R. and Gabrielse, H. (1984): Precam- Griffths, 1. (1984): Rare Earths- Ateacting IncreasingAttlmtion; brian Gneiss andLate Proterozoic Sedimentation in North- Industrial Minerals Magazine,April 1984, pages 19-37. central British Columbia; Geology, Volume 12, pages Gussow, W.C. and Hunt,C.W. (1959): Age ofthe IceRive]. Corn.- 233-237. plex, Yoho National Park, BritishColumbia;Al,berta Society Fenton, M.D. and Faure, G. (1970): Rb-Sr Whole Rock Age De- of Petroleum Geologisfs,Journal, Volume 7, pxge62. terminations of the Iron Hill and McClure Mountain Car- Haggerty, S.E. (1986):DiamondGenesisinaMultipl~-consrained bonatite-alkaline Complexes, Colorado; JMounfain Model; Nature, Volume 320, pages 34-38. Geologist, Volume 7, Number 4, pages 269-275. Hall, D.C., Helmstaedt, H. and Schulze, D.J. (1986): The Cross Fernandes, T.R.C. (1989): The Phosphate Industry of Zimbabwe; Diatreme: A Kimberlite in Younga Orogenic Belt; Gt?ologi- Industrial Minerals Magazine,November 1989, pages 71- cal Society of Australia, 4th International Kimberlit: Con- 77. ference, Abstract Series Number16, pages 30-32. Fisher, R.V. and Schmincke, H.U. (1984): Pyroclastic Rocks; Halleran, A.A.D. (1980): Petrology, Mineralogy andOrigin of the Springer-Verlag,472 pages. Niobium-bearing Lonnie CarbonatiteComplex of thm: Man-

" I20 Geological S~rrvey3ranch son Creek Area, British Columbia; unpublished B.Sc. thesis, bia; B.C. Ministry of Energy, Mines and Petdeum Re- The University of British Columbia,41 pages. sources, Bulletin 80. Halleran, A.A.D. (1988): Geology, Geochemistry and Geophysics,Hby, T. and Godwin, C.I. (1988): Significance o:FCamlxian Dates Ursa Property; B.C. Ministry of Energy, Mines and Petro- from Galena-lead Isotope Data for the Stratiform Cottonbelt leum Resources,Assessment Report 17 872. Deposit in the Monashee Complex, Southeastern British Co- Halleran, A.A.D. and Russell, J.K. (1990): Geology and Descrip- lumbia; Canadian Journal of Earth Scieuces, Volume 25, tivePetrology of theMount Bisson Alkaline Complex, Mun- pages 1534-1541. roe Creek, British Columbia (93N/9E, 930/12W, 5W); in Hay, T. and Kwong, Y.T.J. (1986): The Mount Grace Carbonatite Geological Fieldwork 1989,B.C. Ministryof Znetgy, Mines -a Niobium and Light RareEarth Element-enrickd Marble and Petroleum Resources,Paper 1990-1, pages 297-304. of Probable Pyroclastic Origin in the Shuswap Complex, SoutheasternBritishColumbia; Economic Geology, Volume Hankinson, J.D. (1958): The Lonnie Group Columbium Deposit; 81, pages 1374-1386. unpublished BSc. thesis, The University of British Colum- bia, 32 pages. HBy, T. and McMillan, W.J. (1979): Geology in the Vicinity of Frenchman Cap Gneiss Dome (82M);in 13eolo;:ical Field- Harben, P.W. and Bates, R.L. (1990): Wollastonite; in Industrial work 1978, B.C. Ministry of Energy, Mines a& Petroleum Minerals, Geology and World Deposits, pages 299-301. Resources, Paper 1979-1, pages25-30. Hausel, W.D., Glahn, P.R. and Woodzick, T.L. (1981): Geological Hay, T. and Pell, J. (1986): Carbnatites and Associated Alkalic and Geophysical Investigations of Kimberlite in theLaramie Rocks, Peny River and Mount Grace Areas, Shurwap Com- Range of Southeastern Wyoming; Geological Survey of plex, Southeastern British Columbia (821N7, 13); in Geo- woming, Preliminary Report Number18. logical Fieldwork 1985,B.C. Ministry ofEnergy, Mine.rand Hausel, W.D., McCallum, M.E. and Woodzick, T.I... (1979): Ex- Petroleum Resources, Paper 1986-1, page:r69-81. ploration for Diamond-bearing Kimberlite in Colorado and Ijewliw, 0.1. (1986): ComparativeMineralogyof Three Ultramafic Wyoming: an Evaluation of Exploration Techniques;Geo- DiatremesinSoulheasternBritishColumbia-C~oss,Black- logical Surveyof Wyoming,Report of Investigations 19. foot and HP; unpublished BSc. thesis, The Lrliversity of Hawthorne, J.B. (1978): Model of a Kimberlite Pip; in Physics British Columbia,61 pages. and Chemistry of the Earth, Volume 9, Ahrens, L.H., Ijewliw,O.I.(1987):ComparativeMineralogyofThreeUltr~nafic Dawson, J.B., Duncan, A.R. and Erlank, A.J., Editors,Per- Breccia Diatremes in Southeastern British Columbia, Cross, magon Press, Oxford, pages 1-15. Blackfoot andHP(82J,82G, 82N); in GeologicalFieldwork Hay, R.L. (1983): Natrocarbonatite Tephra of Karimasi Volcano, 1986, B.C. Ministry of Energy, Mines adPetroleum Re- Tanzania; Geology, Volume 11, pages 599-602. sources, Paper 1987-1, pages 273-282. Hearn, B.C. (1968): Diatremes with Kimberlitic Affinities in Ijewliw, O.J. and Schnlw, D.J. (1988):The HPPipe, al’reliminary North-central Montana; Science, Volume 159, pages 622- Report; in Geological Fieldwork 1987,B.C. Ministryof En- 625. eRy, Mines and Petroleum Resources,Paper 19 38-1, pages 369-374. Hearn, B.C. and McGee, E.S. (1983): Garnet in Montana Diatre- mes: a Key to Prospecting for Kimberlites; United States Ijewliw, O.J. and Schulw, D.J. (1989) The Golden Cluster of Dia- Geological Survey.Bulletin 1604. tremes and Dikes;in Exploration in British Columbia 1988, B.C. Ministry of Energy, Mines and Petndeum Resources, Heinrich, E.W. (1966): The Geology of Carbonatites; Robert E. pages B39-B46. Krieger Publishing Company,585 pages. Jacques, A.L., Boxer, G., Lucas, H. and Haggxty, S.E. (1986): Helmstaedt,H.H.,Mott, J.A.,Hall,D.C.,Schulze,D.J.andDixon, Mineralogy and Petrology of the Argyle Lamproite Pipe, J.M. (1988): Stratigraphic andStructuralSettingofIntrusive Western Australia; Geological Society of Austritlia, 4th In- Breccia Diatremes in the White River - Bull River Area, ternational Kimberlite Conference, pages 48-50 Southeastern British Columbia; in Geological Fieldwork Jaffe, H.W. (1955): Precambrian Monazite and. Zircm from the 1987, B.C. Ministry of Energy. Mines and Petroleum Re- Mountain Pass Rare-earth District, San Bernadno County, sources, Paper 1988-1, pages 363-368. California; GeologicalSociety ofAmerica:Bulletin, Volume Hendrick, J.B. (1985): Rare-earth Elements and Ymium;in Min- 66, pages 1274-1256. eral Facts and Problems, United States Department of the Jones, W.C. (1955): Geology of the Garnet Mountain - Aquila Interior, Bureau of Mines, Bulletin 675, pages 647-664. Ridge Area,Ice River, British Columbia; unpubl [shed M.Sc. Hildebrand, EA. and Conklin, N.M. (1974): A Breccia Dike Con- thesis, The University of British Columbiu,57 pages. taining Rare-earth-bearing Apatite, Molybdenite and Mag- Journeay, M. andBr0wn.R.L. (1986):MajorTectonicBoundaries netite at Iron Hill, Cnster County, Colorado: Economic of the Omineca Belt in Southern British Columbia: a Pro- Geology, Volume 69, pages 508-515. gressReport;inCurrentResearch,PartA,cieolo(.icalSurvey Hora, Z.D. and Kwong, Y.T.J. (1986): Anomalous RareEarth Ele- of Canada,Paper 86-lA, pages 81-88. ments (REE) in the DeepPurple and Candy Claims;in Geo- Keller, J. (1981): Carbonatitic Volcanism in the Kaiseistuhl Alka- logical Fieldwork 1985,B.C. MinistryofEneqy, Minesand line Complex: Evidencefor Highly Fluid (:arbor.atiticMelts Petroleum Resources,Paper 1986-1, pages 241-242. of the Earth‘s Surface;Journal ofValcanoiogy ad Geother- Hovdebo, H.R. (1957): Swcture of the Brule - Crossing Creek mal Research, Volume 9, pages 423-431. Area, British Columbia; unpublishedMSc. thesis, Univer- Lang, A.H., Amstrong, J.E. and Thurber, J.B. (1945): Manson sity of Saskatchewan, 46 pages. Creek: Geological Surveyof Canada, Map 876.L Hay, T. (1988): Geology of the Cottonbelt Lead-Zinc-Magnetite Larsen, E.S. (1942): Alkalic Rocks of Iron Hill, 13unni.ion County, Layer, Carbonatites and Alkalic Rocks in the Mount Grace Colorado; United States Geological Surve:,, Profissional Pa- Area, Frenchman Cap Dome, Southeastern British Colum- per 197A.

~~Bulletin 88 121 " ~~~~~~~

~~British Columbia "~~

Le Bas, M.J. (1977): Carbonatite-Nephelinite Volcanism; John McMillan, W.J. (1973): PetrologyandStructureof the West:;lank, Wiley and Sons Ltd., 347 pages. Frenchman'sCapDome,nearRevelstoke,BritishColumbia; Le Bas, M.J. (1981): Carbonatite Magmas;MineralogicalMaga- Geological Survey of Canada, Paper 71-29. zine, Volume 44, pages 133-140. McMillan, W.J. and Mwre, J.M. (1974): Gneissic Alkalic Rocks Le Bas, M.J. and Dixon, J.A. (1965): A New Carbonatite in the and Carbonatites inFrenchman Cap Gneiss Dome,Shlswap Legetet Hills, Kenya;Nature, Volume 207, page 68. Complex,BritishColumbia;CanudianJournal ofEarrhSci- ences, Volume 11,pages304-318. Lee, K.Y. (1970): Some Rare-earth Mineral Deposits in Mainland China; United States Geological Survey, Bulletin 1312-N, Meeks, D.P. (1979): Geology and Petrology of the Cross Kimber- 33 pages. lite, Crossing Creek Area, British Columbia; nnpntlished B.A.Sc.thesis, The UniversityofBritish Columbia,31 pages. Leech, G.B. (1960): Fernie (82G) West Half; Geological Survey of Canada,Map 11-1960. Meyers, E. (1977): Reconnaissance Geological, Magnetometer and Scintillometer Survey, Verity and Paradise Creek Ura- Lis,M.G.andPrice,R.A.(1976):LargeScaleBlockFaul~ingDur- nium-Columbium Prospect, Kamloops Mining Division; ing Depositionof the Windermere Supergroup (Hadrynian), B.C. Ministry of Energy, Mines and Petroleum Resmrces, in Southeastern British Columbia; in Report of Activities, Assessment Report 6741. Part A, Geological Survey of Canada, Paper 76-1A, pages 135-136. Mortensen, J.K. (1979): Kananaskis Lakes Map Area;Geological Loring, A.K. and Armstrong, D.G. (1980): Cambro-Ordovician Survey of Canada, Open File 634. SyenitesofNewMexico,partofaRegionalAlkalicIntrusive Montgomery, J.R. (1985): Structural Relations of lhe Southern Episode; Geology, Volume 8, pages 344-348. Quesnel Lake Gneiss, Isosceles Mountain Area, Southwest- Lowdon, J.A. (1960): Age Determinations by the GeologicalSur- ern Cariboo Mountains, British Columbia; 'unpublished vey of Canada;Geological Survey of Canada,Paper 60-17, M.Sc. thesis, The University of British Columbia,96 pages. 51 pages. Mortensen, J.K. (1982): Geological Selting and Tectonic Signifi- Miider, U.K. (1986): The Aley Carbonatite Complex; unpublished cance of Mississippian Felsic Metavolcanic Rocksin the MA.thesis, The University ofBritish Columbia,1'76pages. Pelly Mountains, Southeastern Yukon Temtory; Calradian Journal of Earth Sciences, Volume 19, pages8-22. Mader, U.K. (1987): The Aley Carbonatite Complex, Northern Rocky Mountains (94B/5), British Columbia;in Geological Mortensen, J.K. (1986): U-Pb Ages for Granitic Orfuoglleisses Fieldwork 1986,B.C. Ministryof Energy, Mines andPetro- from Western Yukon Territory: Selwyn Gnei!;s and Fifty- leum Resources, Paper 1987-1, pages 283-288. mile Batholith Revisited;in Current Research, PartE, Geo- logical Survey of Canada,Paper 86-1B, pages 141-146. Mader, U.K. and Greenwood, H.J. (1988): Carbonatites and Re- lated Rocks of the Prince and George Claims, Northern Mortensen, J.K., Montgomery, J.R. and Fillipone,J. (1987): U-Pb Rocky Mountains (93J, 931);in Geological Fieldwork 1987, Zircon, Monazite and Sphene Ages for Granitic Orthc,gneiss B.C. Ministry of Energy, Mines and Petroleum Resources, of the Barkerville Terrane, East-central British Columbia; Paper 1988-1, pages 375-380. Canadian Journal of Earth Sciences, Volume 24, No. 6, pages 1261-1266. McCallum, M.E. and Marbarak, C.D. (1976): Diamond in State- Line Kimberlite Diatremes, Albany County, Wyoming; Molt, J.A., Dixon, J.M. and Helmstaedt, H. (1986): Ordovician Larimer County, Colorado;Geological Survey ofWyoming, Stratigraphy and the Structural Style at theMdn Ranges - Report of Investigation Number12. Front Ranges Boundary near Smith Peak, Britirzh~mbia; Col in Current Research, Part B,Geological Survey ofCmnad~, McCallum, M.E., Egg1er.D.H. andBurns,L.K. (1975): Kimberlite Paper 86-IB, pages 457-465. Diatremes in Northern Colorado and Southern Wyoming; Physics and Chemistry of the Earth, Volume 9, pages 149- Nasb, W.P. (1972): Mineralogy and Petrology ofIron the H.11 Car- 162. bonatite Complex, Colorado; Geological Society of Amer- ica, Bulletin, Volume 83, pages 1361-1382. McCammon, J.W. (1951): Lempriere; B.C. Ministry of Energy, MinesandPetroleum Resources,AnnualReport 1950,pages Northcote, K.E. (1983a): Report on Mark Properly, Pangman Peak 229-230. (82N/15W); B.C. Ministry of Energy, Mines aldPetdeum Resources, Assessment Report 13 596. McCammon, J.W. (1953): Lempriere; B.C. Ministry of Energy, MinesandPetroleumResources,AnnnalReport1952,pages Northcote, K.E. (1983b): Reporton Jack Claims,Leas Mcnmtain A115-AI19. (82N/14E); B.C. Ministry of Energy, Mines aid Petwleunl McCammon, J.W. (1955): Lempriere; B.C. Ministry of Energy, Resources, Assessment Report 13 597. MinesandPetroleum Resources,Annual Report 1954, pages Okulitch, A.V. (1985):PaleozoicPlntonisminSoutheastern Britisl~ Alll-A112. Columbia; Canadian Journal of Earth Science:?,Volume 22, McLemore, V.T. (1984): Carbonatites in the Lemitar and Chupad- pages 1409-1424. era Mountains, SOCORO County, New Mexico;New Mexico Okulitch, A.V., Loveridge, W.D. and Sullivan, R.W. (1981): Pre- GeologicalSocieiy, Guidebook, 34th Field Conference,So- liminq Radiometric Analysesof Zircons from the Mount corro Region 11,1983. pages 235-240. Copeland Syenite Gneiss, Shnswap Metamorphic Complex, McLemore, V.T. (1987): Geology and Regional Implications of British Columbia; in Current Research, PartA, Geological Carbonatites in the Lemitar Mountains, Central New Mex- Survey of Canada,Paper 81-1A. pages 33-36. ico, Journal of Geology, Volume 95, pages 255-70. Okulitch, A.V., Wanless, R.K. and Loveridge, W.D. (197:j): De- McMillan, W.J.(1970):WestFlank,FrenchmanCapGneissDome, vonian Plutonism in South-central British Columbia;Cana- Shuswap Terrane, British Columbia;in Structure of the Ca- dian Journal of Earth Sciences,Volume 12, prlges 1760-9. nadian Cordillera,Geological Associationof Canada, Spe- Olson, J.C. and Wallace, S.R. (1956): Thorium and Rae-earth cia1 Paper Number 6, pages 99-106. Minerals in the Powderhorn District, Gnnnison (!ounty, ___ I22 Geological SUW~Branch Ministry of Energy, Mines andPet)%, Resourres

Colorado: United States GeologicalSurvey,Bulletin 1027- Pride, K.R., Leconteur,P.C. andMawe1,A.B. (1986): Geology and 0, pages 693-721. Mineralogy of the Aley Carbonatite, Ospika I:iver Area, Olson,J.C.,Shawe,D.R.,Pray,L.C.andSharp,W.N.(1954):Rare- British Columbia:Canadian Institute ofh!ining and Metal- earth Mineral Deposits of the Mountain Pass District, San lurgy, Bulletin, Volume 79, Number 891, Ahstra:t, page 32. Bernadino County, California; United States Geological Raeside, R.P. and Simony, P.S. (1983): Stratigraphy an,iDeforma- Survey, Professional Paper 261. tional History of the Scrip Nappe, Moniishee Mountains, Parker, R.L. and Sharp, W.N. (1970): Mafic-Ultrarnafic Igneous British Columbia:Canadiun Journal of Earth Sc.ences, Vol- Rocks and Associated Carbonatites of the Gem Park Com- ume 20,639-650. plex, Custer and Fremont Counties, Colorado;United States Rapson, J.E. (1963): Age and Aspectsof Metamorphism Associ- Geological Survey, Professional Paper 649. ated with the Ice River Complex, British Colnmtia;Bulletin Panish, R.R. and Armstrong, R.L. (1983): U-Pb Zircon Ages and ofCanadianPetmleumGeology,Volumell,pag:s116-124. Tectonic Significance of Gneisses in Srmctural Culmina- Rapson,J.E.(1964):IntrusiveCarbonateintheIceRiv~rComplex, tions of the Omineca Crystalline Belt, British Columbia; BritishColnmbia;Canadian Mineralogist,Ahstr~ctVolume GeologicalSociety ofAmerica,Abstracts with Programs15, 8, page 138. page 3U. Read, P.B. and Brown, R.L. (1981): Columbia River :?aukTone: Panish, R.R., Heinrich, S. and Archibald, D. (1987): Age of the Southeastern Margin of the Shuswap and Monashee Com- Ice River Complex, Southern British Columbia;Geological plexes, Southern British Columbia; Canadian Journal of Survey of Canada, Paper 87-2. Earth Sciences,Volume 18, pages 1127-1 145. Pecora, W.T. (1956): Carbonatites: a Review; Geological Society Roberts, M.A., Skall, M. andPighin, D.L. (1980) DiaWemes in the ofAmerica, Bulletin, Volume 67, pages 1537-1556. Rocky Mountains of Southeastern British Columbia:Cana- Pell, J. (1987a): Alkaline Ultrabasic Rocks in British Columbia: dian Institute of Mining and Metallurgy, Bulletin, Volume Carbonatites, Nepheline Syenites, Kimberlites, Ultramafic 71, Number 821, Abstract,pages 74-75. Lamprophyres and Related Rocks:B.C. Ministryof Eneqy, Rock, N.M.S. (1986): The Nature and Originof Ultra'nafk Lam- Mines and Petroleum Resources,Open File 1987-17. prophyres: Alnoites and AlliedRocks;JoumlqfPetrology, Pell, J. and Simony, P.S. (1987): New Correlations of Hadrynian Volume 27, pages 155-196. Strata, South-central British Columbia;Canadian Journal Root, K.G. (1983): Upper Proterozoic andPaleozoic Stratigraphy, of Earth Sciences,Volume 24, pages 302-13. Delphine Creek Area, Southeastern British Columbia: Im- Pell, J., Culbert, R.R. and Fox, M. (1989): The Kechika Yttrium plications for the Porcell Arch;in Current Research, Part A, and Rare-earth Prospect(94Lfll,12 and 13); in Geological GeologicalSurvey of Canada, Paper 83-1.4, pages 377-380. Fieldwork 1988,B.C. Ministryof Eneqy,Mines andPetm- leum Resources, Paper 1989-1, pages 417-421. Rowe, R.B. (1958): Niobium (Columbium) Deposits of Canada; GeologicalSurveyofCanada,Economic(ieolo~ySeries18, Pell, I., Martin, L.M., Culbert, R.R., Moms, R.J. and Leighton, 103 pages. D.G. (1990): Geology of the Kechika Yttrium-Rare Earth Prospect, Northern British Columbia (abstract): Canadian Rnssell,A.(1987):PhosphateRock:TreudsinPl'ocessingandPro- Institufe of Mining and Metallurgy. duction; Industrial Minerals Magazine, Septe:nber 1987, pages 25-59. Perkins, M.J. (1983): Structural Geology and Stratigraphy of the Northern Big Bend of the Columbia River, Selkirk Moun- Schiarizza,P.andPreto,V.A.(1987)GeologyofiheAdamsPlatean tains, Southeastern British Columbia; unpublished Ph.D. - Clearwater - Vavenby Area; B.C. Mmistry of Energy, thesis, Carleton University, 238 pages. Mines and Petroleum Resources,Paper 1!)87-2. Peterson, T.D. (1983): A Study of the Mineralogy and Petrology Scott-Smith, B.H. and Skinner, E.M.W. (1984a): A New Look at of the Ice River Complex,Yoho National Park; unpublished Prairie Creek, Arkansas;in Kimberlites and Related Rocks, BSc. thesis, Universify of Calgary, 133 pages. Kornprohst, 1. Editor, Proceedings,3rd Ltremtional Kim- berlite Conference,Volume 1, pages 255-284. Pilcher,S.H.(1983):ReportontheGeologyandGeochemicalSur- veys and Physical Work Conductedon the Ren I, 11, I11 and Scott-Smith, B.H. and Skinner, E.M.W. (1984hj: Dianondifemus IV Claims, Kamloops Mining Division:B.C. Ministryof En- Lamproites, Journalof Geology,Volume 92, pages 433-438. ergy, Mines and Petroleum Resources, Assessment Report Scott-Smith,B.H.,Skinner,E.M.W.andLoney,P.E.(1986):Lam- 11 639. proites from the Luangwa Valley, Eastern Zambia:Geologi- Price, R.A. (1967a): Operation Bow-Athabasca, Alberta and Brit- cal Society of Australia, 4th International Kimberlite ish Columbia; in Report of Activities,Geolo){ical Survey of Conference, pages 87-89. Canada, Paper 67-1A, pages 106-110. Sevigny,J.H.(1987):FieldandStratigraphicRelationshipsoEAm- Price, R.A. (1967b): Golden, East Half, Map Area (82N E1/2), phibolites in the Late Proterozoic HorsethiefCxek Group, British Columbia and Alberta,in Report of Activities,Geo- Northern Adam River Area, British Columbia;in Current logical Survey of Canada,Paper 67-1B, pages 88-91, Research, Part A,Geological Survey of (:anadgr, Paper 87- Price,R.A.(1981):TheCordilleranForelandThrnstandFoldBelt IA, pages 751-756. in the Southern Canadian Rocky Mountains;in Thrust and Simony,P.S.andWind,B.(1970):Structureofth.eDogloothRange Nappe Tectonics, McCIay , K.R. and Price, N.J., Editors, and adjacent parts of the RockyMountah Tren(:h;Geologi- Geological Society of London,pages 427-448. calAssociation of Canada,Special Paper 6, pal:es 41.31. Pride, K.R. (1983): Geological Survey on the Aley Claims, Smith, C.B. (1983): Rubidium-Strontium, Uranium-Lead and Sa- Omineca Mining Division, British Columbia;B.C. Ministry marium-Neodymium Studies of Kimberlites and Selected of Energy, Mines and Petmleum Resources,Assessment Re- Mantle-derived Xenoliths; unpublished ,'Ph.D. thesis, Uni- port 12018. versify of the Witswatersrand, Johannesborg.

~~- _" Bulletin 88 123 Ministry of Energy, Mines and Petroleun, Resources~~

~~APPENDICES~~

~~__ Bulletin 88 125 British Columbia "~~

~~-~ 126 Geological Su:wey llranch Ministry of Energy, Mines andPet,mleumResources~~

~~APPENDIX 1 RARE EARTH ELEMENT ANALYSES FROM SOME CARBONATITE SUITES~~

~~16 14 119.7 6 3.2 8~~

~~401 1% 213~~

~~Bulletin 88 127 __ 128 Geological Survey Bnanch APPENDIX 2A U-Pb ZIRCON DATA, BRITISH COLUMBIA CARBONATITES AND NEPHELINE SYENITES~~

~~Pb' 2MPb3 Pbc4 Analysis No. wt.' U - '%b2 "6ph +lSEM%' Size' (mg) PPm ppm '"PS (Pg) (%) 23au~~

Trident Mountain nepheline syenite, PCA-307-83 NSY 1.+149ceu 1.674 45.34 5.39 2999 75 64.0 0.4698 64.0 75 2999 5.39 45.34 1.6741.+149ceu (.%) 0.3454 (.lo) 0.5332 (.06) 342.6 (1.2) 2.+149cdeu 2.295 124.6 13.56 1224 496 72.2 0.03327 72.2 496 1224 13.56 124.6 2.+149cdeu2.295 (.08) 0.2373 (.18) 0.05172 (.13) 273.2 (2.9) Paradise Lake nepheline syenite, P4-323 3.+149ceu 1.988 40.98 8.035 2458 11.4 74.7 0.05440 (.18)0.05440 74.7 11.4 2458 8.035 40.98 1.988 3.+149ceu 0.4036 (.21) 0.05382 (.lo) 363.3 (2.2) 4.+149cup 1.872 92.84 15.47 6702 89 70.4 0.05421 70.4 89 6702 15.47 92.84 1.8724.+149cup (.18) 0.4000 (.19) 0.05352 (.05) 350.7 (1.2) Lonnie carbonatite, L4-191 5.+149ceui 1.673 44.28 4.488 461 484 58.7 0.04599 58.7 484 461 4.488 44.28 1.6735.+149ceui (20) 0.34160.05386365.2 (.41)(.36) (8.2)

~~Vergil carbonatite, L4-241 6.+149cf 2.714 75.36 7.676 2969 236 51.7 0.05414 (.18)0.05414 51.7 236 2969 7.676 75.36 2.7146.+149cf 0.05354351.60.3996(2.0)(.07) (1.6)~~

Notes: 'sires (i.e., +1495) refer to length aspect of zircons in microns, e=equant, cd=somewhar cloudy, c=clear, u=euhedral, p=pink, i=contains inclusions,f=fragments and shards; 'radiogenic Pb: 3m~asuredratio, corrected for spikp andfractionation; 'total common Pb in analysis corrected forfractionarion and spike; 'corrected for blank Pb an U,common Pb, errors quoted are I standard ermr %[he mean in percent; 'corrected for blank and common Pb, ermrs are I standard error of rhe mean in Ma: *weighing ermr 0.002 mg. APPENDIX 2B URANIUM-LEAD ANALYTICAL DATA, B.C. DIATREMES

~~5W.7~~

~~3855 13080 2356 I II I~~

~~22910 0.132 6664 0.114~~

~~5751. 2267.8 I 9.8307! 0.665. 17.99 581.3 17.6 1579.3 4.2746 0.221 ~....~~

~~17.51 59.75 80 1W9.72.808292 4.793~~

~~28.98 931 28.04 27WMa~~

~~22 18.76 27W~~

~~a4 13.44 ZIW 0.134~~

~~11.1 0.145 B pinlimd 15080 15.1 0.116 12.4 0.115 2716 11.5 0.121~~

~~8.0 0.576 953.3 1.6294 06.70 4944 6.4 'I0.111 82.50 7485 7.5 0.101 ""*I APPENDIX 2B (continued) "-~~

~~@ MONS CREEK @ VALENCIENNERIVER~~

~~1- 1- .2[ 3 2.00 4.00 6.00 8. io 4.50 6.50 8.50 10.50 207pb/ 235u /20?pb/ 23SU~~

~~O0 A~~

~~IO 2.00 4.00 6.l 207pb/235u~~

~~I 207pb/235u~~

~~_~ Bullelin 88 131 British Columbia -~~

~~APPENDIX 2C SUMMARY OF RbISr ANALYTICALDATA, B.C. DIATREMES~~

Lab Mineral ppm Sr Sample 87Sr/86Sr Number Name T7Initial Rr tio lspika Pipe 33008 phlogophite AL64 103.Oi0.3 432.4i2.7 12.22i0.08 0.7646i1 351i2 Ma 0.7036 30239 phlogophite AL 5-20 134.9i0.4 407.5*2.3 8.7i0.08 0.7471+1 351i3 Ma 0.7036 30238 phlogaphitc AL 5-16 166.8i0.5 387.7S.2 6.75iO.04 0.7361il 338i3 Ma 0.7036 [P Pipe 30240 phlogophite HP- 5 359.9iO.5 8.01iO.06 0.749il 391i5 Ma 0.7040 :ushRiver (Larry) 475.9956 -I LA 6-196 156.1iO.5 F 8.86i0.11 0.7556+1 409i6Ma I 0.7040 I 32961 lphlagophife I

~~132 Geological Survey Branch Minisiry of Energy, Mines and Petroleum ,-~~

~~APPENDIX 2D SUMMARY OF K-Ar ANALYTICAL DATA,B.C. DIATREMES~~

~~K=X=8.2M0.01 % 40'- 139.297~10-~cc/gm) ;(94,6 zrAr40*) ;(Ar - K20= n=2 % 62.159~10"~rnol/gm)~~

~~moterial date 1oerror (Biotite) 391 *12 Ma~~

~~K=X=8.2M0.01 % 40. :(Ar = 139.297~1O-~cc/gm) :(94,6 %rAr40.1 K20= n=2 % 62.159~10-~~mol/grn)~~

~~material date loerror~~

~~(Biotite) 391 f12 Ma~~

OspikaPipe SampleNurnber(s) AL-5-16 AnalyticalData: (list duplicate analyses or indicaten=2, n=3, etc.) K=x=~.~o*o.o~% 40' 108:496~10-~cc/gm) :(95.8 zrAr40*) ;(Ar = K 20= n=3K20= % 48.414~10-~~mol/gm) m aterial date loerrordatematerial (Biotite) +10323 Ma

~~decayconstants 4.96/.581/1.167~~

~~Bulleiin 88 133 - 134 Geological Survey Branch~~