Manson Creek Area, British Columbia (94N/9,10,15; 94C/2)

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

BEDROCK GEOLOGY OF THE GERMANSEN LANDING - MANSON CREEK AREA, BRITISH COLUMBIA (94N/9,10,15; 94C/2)

By Filippo Ferri, P.Geo. and David M. Melville, P.Geo. with contributions by M.J. Orchard (GSC)

BULLETIN 91 Ferri.Filippo. 1959- . Bedrock geology of !he Germansen Landing-MansonCnek area, British Columbia (94N19. IO. 15: 94CR)

(Bulletin. ISSN 02267497 ; 91)

Issued by Geological Survey Branch. Ineludes bibliographical references: p. ISBN 0-77262125-X VICTORIA BRITISH COLUMBIA 1. Geology -British Columbia - Germansen Landing Region. CANADA 2. Geology - British Columbia - Manson Creek Region. 3. Gcology. - British Columbia - Germanscn Landing Economic APRIL 1994 Region. 4. Geology. Economic - British Columbia - Manson Creek Region. I. Melville. David M. 11. BritishColumbia. Ministry of Energy, Mines and Perroleurn Resources. Ill. British Columbia. GeologicalSurvey Branch. IV. TiUc. V. Series:Bulletin (British Columbia. Ministry of Energy. Miner and Peuolcum Resources) ; Fieldwork for this research was 91. carried out during the period I987 to 1989 TN27.B7F47 1994 551.7’00971182C94-960168.3 - ABSTRACT TheGermansen Landing-Manson Creek area is sillimanite grade within the Wolverine Metamorphic Com- located within the southern Omineca Mountains of north- plex. Rocks of the Nina Creek group were imbricated and central British Columbia. This region streddles the Inter- emplaced on top of North American rocks during this time montane-Omineca Belt boundary and encompasses rocks period.Middle to Late(?)Jurassic D2 deformation fromfive tectonostratigraphicterranes and subterrenes. refoldedthese rocks into uprightto northeast and These are: North American siliciclastics and carbonates of southwest(?)-verging structures. D, deformationbroadly the Cassiar Terrene, represented by the Upper Proteroroic warped and uplifted these rocks during theEarly to Middle Ingenika Group through to the Devonian to Permian Big Cretaceous.Late Cretaceous to Tertiaryright-lateral Cresk group; pericratonic clastics of theKootenay Ter- movement along the Manson fault zone was accompanied rent:, comprised of the Upper Proteroroic to Paleozoic('!) by dip-slip motion on the brittle-ductile, southwest-side- Boulder Creek group: the oceanic Slide Mountain Terrane, down Wolverine fault zone in response to uplift of meta- which is made up of deep waterargillites, cherts and morphic rockswithin the Wolverine Complex. Rapid basalts of the Mississippian to Permian Nina Creek group: uplift of these rocks is recorded by early Tertiary K-Ar arc volcanics and sediments of the Triassic to Jurassic(?) cooling dates. Rocks in the hangingwall of the Wolverine Takla Group of the QuesnelTerrane; and theHarper fault 70ne cooledrelatively early in thedeformational Rartch Subterrane. represented by Mississippian(?) to Per- sequence (Middle Jurassic). mian arcvolcanics and sediments of theLay Range The map area contains a wide variety of mineral asst:mblage. occurrences which reflect the long andcomplex history These rocks were polydeformed and strongly meta- recorded by these rocks. The most abundant arepoly- molphosed beginning in the Mesozoic as a result of colli- metallic reins genetically related to the Manson fault zone sion and obduction of exotic terranes from the west. Mid- and spatially related to strongly altered ultramafic bodies. dleJurassic, northeast-verging Dl deformationwas Carhonate-hostedlead-zinc mineralization in the Otter acc8nlnpanied by regionalmetamorphism which reached Lakes group is locally important.

... 111 TABLE OF CONTENTS . ... ABSTRACT ...... 111 Quesnel Terrane ...... 42 INTRODUCTION ...... I Lay Range Assemblage ...... 42 Geographic Setting...... 1 Age and Correlation ...... 42 Geologic Framework ...... I Unit MPlrl ...... 43 Methods ...... 5 Unit MPlr2 ...... 43 Previous Work ...... 7 Evans Creek Limestone ...... 43 ExplorationHistory ...... 9 Age and Correlation ...... 43 Acknowledgments ...... 9 Takla Group ...... 44 Age and Correlation ...... 44 LITHOLOGIC UNITS ...... II Slate Creek Succession ...... 47 Ancestral North American Craton ...... II Plughat Mountain Succession ... 48 Kootenay Terrane ...... II Chemical Composition and Boulder Creek Group ...... II Tectonic Significance of Age and Correlation ...... II Takla Basalts ...... 50 Lithology ...... II Intrusive Rocks ...... 54 Cassiar Terrane ...... 12 Carbonatites...... 54 lngenika Group ...... I2 Wolf Ridge Gabbro ...... 54 Age and Correlation ...... IS Wehrlite ...... : ...... 54 Amphibolite and Calcsilicate Gabbro ...... 54 Gneiss ...... 16 Germansen Batholith and Related Rocks 54 Paragneiss, Schist and Intrusive 16 Monzonite to Quartz Monzonite and Paragneiss and Schist ...... 17 Related Volcanics ...... 55 Impure Metaquartzite ...... Monzonite to Syenite...... 55 Swannell Formation ...... 18 Wolverine Ranee Intrusions ...... 56 TsaydiL Formation ...... 19 Espee Formation ...... 20 STRUCTURE ...... 51 Stelkuz Formation ...... 20 Introduction ...... 57 Atan Group ...... 20 Omineca Belt ...... 57 Age and Correlation ...... 21 Phase 1 ...... 58 Mount Brown Quartzite ...... 22 Phase 2 ...... 60 Mount Kison Limestone ...... 22 Phase 3 ...... 62 Razorback Group ...... 23 Phase 4(?) ...... 63 Age and Correlation ...... 24 Faults ...... 63 Lithology ...... 24 Thrust Faults ...... 63 Echo Lake Group ...... 24 Normal Faults ...... 65 Age and Correlation ...... 25 Wolverine Fault Zone ...... 65 Lower Member ...... 26 Age and Tectonic Implications ...... 66 Sandy Dolomite Unit ...... 26 Discussion ...... 67 Otter Lakes Group ...... 27 lntermontane Belt ...... 68 Age and Correlation ...... 27 Phase I ...... 68 Lithology ...... 27 Phase 2 ...... 68 Big Creek Group ...... 28 East-trending Structures South of the Age and Correlation ...... 28 Evans Creek Fault ...... 68 Lithology ...... 29 Faults ...... 69 Blue Lake Volcanics ...... 31 Evans Creek Fault ...... 69 Age and Correlation ...... 31 Thrust Faults ...... 69 Intermontane Supenerrane...... 31 Normal Faults ...... 69 Slide Mountain Terrane ...... 32 Manson Fault Zone ...... 70 Nina Creek Group...... 32 Timing of Movement ...... 71 Age and Correlation ...... 32 Extensions Outside the Map Area ...... 72 Mount Howell Succession...... 34 Relationship to Wolverine Fault Zone ...... 72 Pillow Ridge Succession ...... 36 METAMORPHISM ...... 13 Chemical Analysis and Introduction ...... 73 Tectonic Setting of the Nina Intermontane Belt ...... 73 Creek Basalts ...... 37 Omineca Belt ...... 73 Manson Lakes Ultramafics ...... 4041 Mineral Isograds...... 74 Age and Correlation ...... Chlorltold ...... 74 Lithology ...... 42 Tourmaline ...... 74 Biotite ...... 76 Appendix VI1 . Regional Geochemical Survey; Garnet ...... 76 stream sedimentgeochemistry ...... 133 Staurolite ...... 77 Appendix VI11 . Regional Geochemical Survey; Kyanite ...... 79 hulkstream-sediment geochemistry ...... 139 Sillimanite 79 Sillimanite ...... Appendix IX . Regional Geochemical Survey; Mu scovite-Out(?) 79 Muscovite-Out(?)...... moss-mat sediment geochemistry ...... 145 Migmatite(?) ...... 79 RetrogradeMetamorphism ...... 79 LIST OF FIGURES Relationship of Metamorphism to Deformation ...... 79 Figure 1. Location of thestudy area ...... 2 Ingenika Group (CassiarTerrane) ...... 79 Figure2 . Physiography of thestudy area ...... 3 Boulder Creek Group (Kootenay Figure 3 . Geomorphological belts of the Canadian Terrane) ...... 80 Cordillera ...... 4 Geothermometry ...... Terrane80 Figure 4 . map ...... 4 Geochronology andTectonic Implications ...... 81 Figure 5 . Regional geology in the vicinity of the ECONOMICGEOLOGY ...... 83 maparea ...... 4 Polymetallic Veins ...... 83 Figure 6 . Unitsand terranes in the study area ...... 5 I - Batholith-related Vein Systems ...... 83 Figure 7 . Geology of the Germansen Landing ~ (1:100000 I1 - Vein Systems related to the Manson MansonCreek area scale) ...... (in pocket) Fault Zone ...... 86 Figure 8 a, b, c . Geochemical sample locations, Type IIA Veins ...... 86 Germansen Landing - Manson Creek map Type IIB Veins ...... 87 area ...... (in Appendix Ill; 121-123) IIC Veins ...... 87 Figure 9 . Location of published geologic maps Type around the study area 7 Alteration ...... 87 ...... Figure IO Stratigraphic column of the lngenika Precious MetalQuartz Veins ...... 88 . DisseminatedGold ...... 88 Group,Southern part of maparea ...... 14 StrataboundBase Metal Occurrences ...... 89 Figure 11. Stratigraphic column of lower Ingenika Group ...... 14 Silicified ShearZone ...... 90 Figure 12. Distribution of Windermere stratigraphy Carbonatites...... 9 I along the CanadianCordillera ...... 16 Rare Earth RichAlkalic lntrusives ...... 92 Figure 13 Paleozoic stratigraphy in the northern Sulphide-richAmphibolite Gneisses ...... 92 . part of the map sheet ...... 22 PorphyryNein Molybdenum92 Occurrences ...... Figure 14. Schematic stratigraphic columns of Ultramafic Mineralization ...... 93 NinaCreek group ...... 33 Stratiform Barite Occurrences ...... 93 Figure 15. Distribution of the Slide Mountain Sedimentary-MetamorphicOccurrences ...... 93 assemblage ...... 33 DisseminatedSulphides 94 ...... Figure 16. Stratigraphic correlation chart of the PlacerDeposits ...... 94 Nina Creek group ...... 34 GEOLOGICAL SYNTHESIS 95 ...... Figure 17. Sample locations of basalts and gabbros TectonicModel ...... 95 used indiscrimination diagrams ...... 38 Proterozoic ...... 95 Figure 18 . AFM plot of Nina Creek basalts and EarlyPaleozoic ...... 95 gabbros ...... 39 LatePaleozoic ...... 97 Figure 19. Plot of total alkali ver.ws silica for Permian to Triassic ...... 98 NinaCreek basalts and gabbros ...... 39 Middle Triassic to EarlyJurassic ...... 99 Figure 20 . TillOO - Zr - Sr/2 for Nina Creek Latest EarlyJurassic to LateJurassic ...... 99 basalts and gabbros ...... 39 Early to Middle Cretaceous ...... 100 Figure 21. TillOO - Zr ~ Yx3 for Nina Creek Late Cretaceous to EarlyTertiary ...... 100 basalts andgabbros ...... 39 REFERENCES ...... 103 Figure 22 . Ti versus Zr for Nina Creek basalts and gabbros ...... 40 APPENDICES ...... 109 Figure 23. TiO, wer.sus Y/Nb for Nina Creek basaltsand gabbros ...... 40 LIST OF APPENDICES Figure 24 . P,O, versus Zr for Nina Creek basalts Appendix 1. Fossil identifications ...... 11 1 andgabbros ...... 40 Appendix I1 . Geochronology of selected Figure 25 . Extended trace element plot for Nina metamorphic and igneous rocks ...... 115 Creek basalts andgabbros ...... 41 Appendix 111. Whole-rockand traceelement data ... 121 Figure 26 . Schematic stratigraphic columns of the Appendix IV . Trace and rare-earth element data .... 128 Takla Group ...... 45 Appendix V. Mineral analyses used for Figure 27 . Diagram showing facies relationships geothermom etry calculations 129 calculations geothermometry ...... of Takla Group units ...... 46 Appendix VI . Lithogeochemistry of various rocks Figure 28 . Total alkali ver.sus silica for Takla from within the map area ...... 131 Group hasalts ...... 50

Vi Figure 29. AFM plot of subalkaline Takla Group Figure 60. Schematic block diagram illustrating basalts ...... 50 the distribution of deposit types in the map Figure 30. Ti/100 - Zr - Yx3 for Takla Group area ...... 86 basalts ...... 57 Figure 61. Chemical changes in a carbonate-

Figure 3 I. Ti ~ Zr ~ Sr/2 for Takla Group basalts .. 51 altered basalt ...... 88 Figure 32. TiO, - MnOxlO - P,O,xlO for Takla Figure 62. Simplified geology of the QCM claim Group basalts ...... 51 group ...... 89 Figure 33. Ti vcr.ws Zr for Takla Group basalts ..... 51 Figure 63. Regional extent of favourable hostrocks Figure 34. Log(Ti0,) wr.?u.r log(Zr) for Takla for stratabound base metal ...... 90 Group basalts ...... 52 Figure 64. Geology of the Nina claim group ...... 91 Figure 35. TiOz wr.ws Y/Nb for Takla Group Figure 65. Geology of the Lonnie carbonatite hasalts ...... 52 complex ...... 91 Figure 36. P,O, wr.nl.v Zr for Takla Group hasalts 53 Figure 66. Placer gold producing drainages within Figure 37. Extended trxe earth element plot for the project area ...... 93 Takla Group basalts ...... 52 Figure 61. Schematic diagram depicting evolution Figure 38. Log (Zr/Y) versus log Zr for Takla of the study area ...... 96 Group hasalts ...... 53 Figure 68. U-Pb concordia plot for Gilliland tuff .... 116 Figure 39. Timing of metamorphic and Figure 69. U-Pb concordia plot for Wolf Ridge deformational events in the study area ...,,...... 51 gabbro ...... 1 I6 Figure 40. Structural domains used in discussion Figure 70. U-Pb concordia.. plot for Wolverine of structural trends ...... 58 Range granodlorlte ...... 1 I6 Figure 41. Equal-area projection of F, fold axes, Figure 71. Apatite fission-track cooling curve southern part of Domain 1 ...... 59 history for sample FFe87-38-4 ...... I I8 Figure 42. Equal-area projectinn of F, fold axes in Figure 72. Apatite fission-track cooling curve the northern part of Domain I ...... 59 history for sample DMe87-3 1 - I2 ...... IIR Figure 43. Equal-area projection of mineral lineations in the northern pan of Domain I..... 59 Figure 44. Equal-area projection of poles to F, LIST OF PLATES crenulation planes Domain I ...... 61 Plate I. The old town site of Germansen, ca. Figure 45. Equal-area projection of poles to S, 1890s ...... 8 cleavage in northern pan of Domain 2 ...... 61 Plate 2. A hydraulic placer mining operation, Figure 46. Equal-area projection of poles to probably along the Germansen River ...... 8 bedding near Blue Grouse Mountain ...... ,,,.,. 61 Plate 3. Raft of metasediments within Figure 47. Equal-area prqjection of poles to granodiorites of the Ingenika Group ._...... 15 bedding within a fold pair, Domain 2 .,...... 62 Plate 4. A pegmatitic sill within the lngenika Figure 48. Equal-area projection of bedding- Group ...... 18 cleavage intersection Domain 2 ...... 62 Plate 5. Coarse quartz to feldspathic wacke Figure 49. Equal-area projection of poles to ("grit") of the Swannell Formation ...... 19 compositional layering. Domain 1 ...... 62 Plate 6. Finely interlayered calcareous shale and Figure 50. Equal-area projection of poles tn limestone of the Tsaydiz Formation ...... 20 compositional layering along the Wolverine Plate 7. Cliffs of Espee carbonates ...... 21 antiform ...... 63 Plate 8. Massive to thickly bedded impure Figure 5 I. Equal-area projection of poles to quartzites of uppermost Stelkuz Formation ...... 21 compositional layering. Domain 1 ...... 63 Plate 9. Orthoquartzites of the basal Mount Brown Figure 52. Equal-area projection of poles to S, quartzite ...... 23 cleavage ...... 63 Plate 10. Mount Kison limestone north of Mount Figure 53. Equal-area projection of mineral Kison ...... 23 lineations in the Wolverine fault zone ...... 67 Plate I I. Dolomitic and argillaceous limestone of Figure 54. Modified tectonic wedging model of the Razorback group ...... 25

Price (I 986) ...... ~ ...... 68 Plate 12. Looking north at Razorback Mountain ..... 25 Figure 55. Fold and fault structures related to Plate 13. Selective quartz replacement of right-lateral strike-slip morion ...... 69 carbonate of the Echo Lake group ...... 26 Figwe 56. Equal-area prnjection of lineations Plate 14. Variably dolomitized algal laminae, Echo along the Manson fault znne ...... 70 Lake group ...... 21 Plate 15. Silicified pisolites, Echo Lake group ...... 21 Figwe 57. Geology of the map area with isograds Plate 16. Grey, extremely fissile shales of the Big and geochronology of metamorphic rocks ...... 75 Creek group ...... 29 Figure 58. Regional geology map with Plate 17. Photomicrograph of quartz-chen metamorphic K-Ar dates ...... 81 sandstone of the Big Creek group...... _...... _. 30 Figure 59. Location of mineral Occurrences in the Plate 18. Fissile argillites of the upper part of the map area ...... 83 Big Creek group ...... 30

vii Plate 19. Interlayered limestone and silicified Plate 42. Photomicrograph of idioblastic garnet limestone of the Big Creek group ...... 31 porphyroblast in the Ingenika Group ...... 76 Plate 20. Photomicrograph of quartz-chert wacke Plate 43. Photomicrograph of helicitic garnet of the Big Creek group ...... 31 porphyroblast in the Ingenika Group...... 77 Plate 21. Ribboned cherts of the Mount Howell Plate 44. Photomicrograph of garnet porphyroblast succession ...... 35 in the Ingenika Group...... 77 Plate 22. Gabbro sills of the Mount Howell Plate 45. Photomicrograph of retrogressed garnet succession ...... 36 porphyrohlast in the Ingenika Group ...... 77 Plate 23. Pillowed basalts of the Pillow Ridge Plate 46. Photomicrograph of staurolite succession ...... 37 porphyroblast showing poikiloblastic texture ... 77 Plate 24. Pillowed basalt of the Slate Creek Plate 47. Photomicrograph of staurolite succession ...... 47 porphyrohlast showing layered inclusion trails 78 Plate 25. Agglomerate of the Plughat Mountain Plate 48. Photomicrograph of staurolite succession ...... 49 porphyrohlast from the Boulder Creek group .. 78 Plate 26. F, fold in schists of the lower Swannell Plate 49. Photomicrograph of kyanite Formation ...... 59 porphyroblast in Ingenika Group schists ...... 78 Plate 27. Tight chevron fold in Big Creek shales .... 60 Plate 50. Photomicrograph of sillimanite needles Plate 28. Flat-lying F, fold ...... 60 in lngenika Group schists...... 78 Plate 29. Thrust fault between Manson Lakes Plate 51. Migmatite(?) in amphibolite gneiss of ultramafics and Boulder Creek sediments ...... 64 unit Pipi north of Munro Creek ...... 78 Plate 30. Photomicrograph of fault breccia from Plate 52. Photomicrograph of garnet in schists of the Wolverine fault zone ...... 66 the lngenika Group ...... 80 Plate 31. Photomicrograph of rocks from a ductile Plate 53. Outcrop of listwanitired augite- portion of the Wolverine fault zone ...... 66 porphyritic Takla basalt ...... 87 Plate 32. Shear-bands within ductile portion of the Wolverine fault zone ...... 67 LIST OF TABLES Plate 33. Steep foliation within granodiorite of the Germansen batholith ...... 69 Table 1. Table of Formations ...... 6 Plate 34. Brecciated rocks within the Manson fault Table 2. Correlation chart of Paleozoic zone ...... 70 stratigraphy in theNorth AmericanCordillera 13 Plate 35. Fault breccia of Boulder Creek group Table 3. Correlation of Proterozoic sequences in within the Manson fault zone ...... 70 Plate 36. Fault contact between Slate Creek CordilleraCanadian the ...... 17 argillites and Manson Lakes ultramafics ...... 71 TableCorrelation4. of TaklaGroup rocks 46 ...... Plate 37. Photomicrograph of ankerite Table 5. Geothermometry of samples from the porphyroblasts in Slate Creek argillites ...... 73 IngenikaGroup ...... 80 Plate 38. Photomicrograph of chloritoid Table 6. Known mineral occurrences within the porphyroblast84-85 in Ingenika Grouparea phyllite ...... 74 study ...... Plate 39. Photomicrograph of chloritoid Table 7. U-Pb data for selected igneous and porphyroblasts in the lngenika Group schist 74 m etamorphic rocks 117 ....rocks metamorphic ...... Plate 40. Photomicrograph of tourmaline porphyroblast in the Ingenika Group ...... 76 Table 8. Apatite fission-track analyses of selected Plate 41. Photomicrograph of biotite and rocks from the Wolverine Complex ...... 118 muscovite in the Ingenika Group ...... 76 Table 9. K-AI Analytical data ...... 118

... "lll - INTRODUCTION Mapping in the Manson Creek-Germansen Landing morphological belts of the Canadian Cordillera (Wheeler area was undertaken by the British Columbia Ministry of and McFeely, 1991). It is underlain by rocks of the Inter- Energy,Mines and Petroleum Resources in orderto montane Superterrane (i.e.,accreted, Monger et a/., 1982) provide a detailed geological database for a poorly under- and rocks representing the displaced North American mar- stcmod belt of rocks long known to host lode gold and base gin (Wheeler and McFeely, ibid.; Figures 3 and 4). Rocks metaloccurrences. The main aims of this project were: of ancestral North America (Foreland Belt) lie to the east, To produce 150 0"scale geological maps for all or across the Rocky Mountain Trench. parts of map sheets 93N19 (Manson Lakes), 93N110 In this area, the Intermontane Superterrane is repre- (GermansenLake). 93N115 (GermansenLanding) sented by volcanic and sedimentary rocks of the Quesnel and 94C12 (End Lake). and Slide Mountainterranes (Figure 5). Quesnel rocks Revisethe mineral inventory database (MINFILE!. comprise a volcanic and sedimentary assemblage assigned to the Middle Triassic to Lower Jurassic(?) Takla Group, Place known mineral occurrences within a geological and a poorlydefined sedimentary and volcanic suite framework. belonging to the upper Paleozoic Lay Range assemblage Complementing this was the augmentation of existing which is believed to be part of the Harper Ranch Subter- Regional Geochemical Survey (RGS) coverage or the rane (Gordey er nl., 1991; Figures 4 and 5). The Slide initiation of new RGS surveys in areas lacking pre- MountainTerrane is represented by upper Paleozoic vious coverage. oceanic rocks of the Nina Creek group and the Manson Lakes ultramafics. The west side of the Quesnel Terrane is GEOGRAPHIC SETTING intruded by the multiphase, Triassic to Cretaceous Hogem batholith (Garnett, 1978). bounded on its west side by the The study area is located some 200 kilometres north- Pinchi fault, which separates Quesnel Terrane from middle northwest of Prince George and containsthe settlements of Paleozoic to Triassic rocks of the Cache Creek and Stikine MansonCreek and Germansen Landing (Figure I). Pri- terranes. maryaccess is by all-season gravelroads from Fort St. Rocks of NorthAmerican affinity within the map James or Mackenzie. These roadsconnect to secondary area are part of the para-autochthonous Cassiar Terrane roads along the Manson River, Germansen River and Ger- andpericratonic Kootenay Terrane. These terranes are mansen Lake, Osilinka River and the Nina Creek-Nina displaced portions of the ancestral North American mar- Lake drainage systems. This road system provides access gin. The Cassiar Terrane is represented by a Proterozoic to ' to approximately 50% of the area. The remainder of the Permian carbonate and siliciclasitic wedge which includes are,a can be reached on foot, or by boat or helicopter. strata of the Proterozoic lngenika Group to the Devonian The study area lies within the Swannell Rangesof the to Permian Big Creek group (Figure 6,Table I). The lower Omineca Mountains (Figure I).The eastern side of the parts of the Ingenika Group are metamorphosed to upper area is bounded by the Wolverine Range with its eastern amphibolite gradeand polydeformed,and are included slopes falling off into the Rocky Mountain Trench (now within the Wolverine Complex, one of several core com- occupied by Williston Lake). The northern and southern plexes found along the length of the Omineca Belt. boundaries roughly coincide with the Osilinka and Man- son rivers. respectively (Figure 2). The western part of the The Kootenay Terrane is composed of the Boulder map area is occupied by the Hogem Rangeswith the Creek group, of uncertain age. Rocks of the Manson Lakes Gel-mansenRange to thesouthwest and a rugged, ultramafic suite have been thrust onto it and its margins unnamed range of mountains to the northwest. are believed to be splays of the Manson fault zone. A large part of the southern section is drift covered. Rocks in the study area trend northwesterly and, as a Glaciofluvial material is widespreadalong the Manson generalrule, dip to thesouthwest. In the southeast,the andGermansen River drainage systems. Most of the contactbetween the Cassiar Terrane and Intermontane slopes are tree covered in the south with alpine vegetation Superterrane is awest-side-down normal fault which is covering less than 20% of the land area. To the north the termed the Wolverine fault zone. It is believed to be an topography is more rugged and the amount of alpine area Eocene normalfault related to uplift of the Wolverine increases substantially. The highest peaks in the area are Complex. In the southwest it placesmiddle to upper slightly over 2150 metres in elevation with the Omineca amphibolitegrade rocks of the Ingenika Group and River valley being roughly 750 metres above sea level at Wolverine Complex against greenschist facies rocks of the the settlement of Germansen Landing. The best outcrops NinaCreek group. Northwest of MansonCreek the are restricted to alpine areas, steeper slopes, hill tops and Wolverine fault zone veers northward, following the edge steep-sided creeks. of the Wolverine Range, and juxtaposes lngenika rocks of different metamorphic grade. In thenorthern part of themap area, fossildata GE:OLOGIC FRAMEWORK confirm that the apparentconformable contact between the The study area lies along the boundary between the CassiarTerrane and theIntermontane Superterraneis a Intermontane and Omineca belts, two of the five geo- major, layer-parallel, thrust fault. Figure I. Location of the study area with main physiographic features indicated.

2 Figure 2. Physiography of the study area Figure 3. Location of map area within geomorphological belts of the Canadian Cordillera. Shaded area represents region portrayed in Figures 4 and 5.

Figure 4. Terrane map centred on the map area. NA - Cratonic North America: CA - Cassiar Terrane: KO - Kootenay Terrane; SM - Slide Mountain Terrane; QN - Quesnel Terrane: QNHR- HarperRanch Subterrane; CC - CacheCreek Terrane: ST - Stikine Terrane.

Figure 5. Regional geology in the vicinity of the map area. WC - Wolverine Complex; Ig - Ingenika Group: Ta - Takla Group; CC - Cache Creek Group; B - Bowser Lake Group; VS - Mesozoic to Cenozoic volcanic and igneous rocks: CDM - Lower Paleozoic sequence; HB - Hogem batholith: GB - Germansen batholith; LR - Lay Range assemblage; SM - Nina Creek group and equivalents:P - Proterozoic to LowerCambrian sediments; PM - Paleozoic to Mesozoic sediments: US - undeformed Mesozoic sediments. ‘Zig-zag’ line roughly corresponds to the westward shale-out of Lower Paleozoic platformal carbonates; c - carbonates, s - shale.

4 I INTERMONTANE SUPERTERRANE NORTH AMERICA I Quesnellia I Slide Mountain t Koofenay Cossior

Evonr Creek t Limestone P Pillow H owell RidgeHowell Succession Succession Range 7P assemblage Big Creekgp. i

D OtlerLakes gp. .~ EchoLake S group 0

€

Stelkuz Fm.

m C

Figure 6. Position of main stratigraphic mils of the study area within the terrane hierarchy of the Canadian Cordillera

Thc mmst notable structure in the area is the Manson Apprnximately 445 thin sections were cut from sari- fault Tone. a vertical. right-lateral fault of unknown dis- pies collected in the study area. These were very helpful in pl;sement. The age of tnwetnent on this fault is helieved determining mineral composition,metamorphic mineral to he h-om C'retacrous to early Tcertial-y (see Structure assemhlages and textucal relationships of rnctarnorphic chapter). 'The fault Tone trends tn the nc~rthwest and fo- minerals. lows segments of the Manson Lakes, GermansenRiver Samples were collected for uranium-lead(U-Pb), and Nina Crcck drainage wstems (Figure 7, in pocket). potassium-argon (K-Ar) andfission-track analysis. The This structural mnc is economicallyimportant as all UPh and K-AI analyses were performed at laboratories at known placer c)perations and precious nletal shw\ings in the University of British Columbia and the fission track tht: area arc associnted uith it. analyses were carried out at theRensselaer Polytechnic Institute of Troy, New York. METHODS Some 11f the leidhearing mineral showings were The area was mapped durinp the summers of 1987, sampled for lead isotope analysis. These analyses were 1988 and 1989 at a scale of 125 000 using enlargements carried out at the University of British Columbia. made from 150 000 NTStopographic sheets. Data and Severalhundred samples were collected for whole- sample points were located on maps and air photos. TG- rock lithogeochemicalanalyses; most were analyzed by verses were madeprimarily along ridgecrests and, to a the Ministry of Energy, Mines and Petroleum Resources lewr extent,along creek valleys. Alpine areas were laboratory in Victoria. Some whole-rock and trace element reachedprimarily by helicopter.The lower timhered analyses were performed at laboratories of Cominco Ltd. slopes were accessed by loggingroads or boat.Use of and Memorial University of Newfoundland. binoculars, camera and sketch book were both helpful and Chemical analyses used in geothermometry calcula- necessary,especially in therugged terrain to the tions were performed using the ARL microprobe at the northwest. University of Calgary. TABLE 1 STRATIGRAPHIC TABLE OF FORMATIONS FOR ALL UNITS WITHIN THE MAP AREA

THICK- GROUPor MAP ERA NESS LITHOLOGY FORMATION UNIT (metres)

LCI

6 Standard streamsediment and moss-mat samples mapping in thePrince George andMcBride map areas. were collected throughout the area. Heavy mineral sepa- Mansy and Gabrielse (1978) described Proterozoic rocks rates were collected in thesouthern two-thirds of the of the northern Cassiar Terrane and proposed the present reglon. Samples weretaken to supplement an existing nomenclature for these rocks. Preliminary reports of the RegionalGeochemical Survey in thesouthern three- geology of the Finlay and Swannell Ranges include Mansy quarters of the maparea. Analyseswere performed by (1971, 1972, 1974) and Mansy and Dodds (1976). Even- ACME AnalyticalLaboratories Ltd. in Vancouver, B.C. chick (1988)compared Proterozoic stratigraphy and struc- Analytical resultsare tabulated in appendicesto this tures within the Deserters and Sifton ranges (on each side report. Sample locations are plotted on Figure 8 a. b, c (in of thenorthern Rocky Mountain Trench). Bellefontaine Appendix 111). (1989,1990) and Bellefontaine and Minehan (1988) Equal-area plots were produced using thepersonal describedIngenika Group rocks withinthe Swannell computer software program SPLOT. Ranges and unraveled the kinematic relationships between the Omineca and Intermontane belts. Parrish (1976) carriedout a detailedstructural, metamorphic and geo- PREVIOUS WORK chronologicalstudy of theIngenika Group near Aiken Lake. This was followed by a more regionalsynthesis The first geological reconnaissance of the area was (Parrish,1979) of rocks in thenorthern part of the carried out by McConnell (1896) who examined the geol- Omineca Belt. Monger (1977b) described Takla Group ogy along the Finlay and Omineca rivers. Camsell (1916). volcanics northwest of the study area, in the McConnell Kel-r (1934)and Lay (1926,1934, 1936 and 1939) Creek area described placer deposits and bedrock geologyin the Man- son Creekand GermansenLanding areas.Lang (1941, 194.2) produced preliminary maps of the Manson Creek areawhich also documented the known mineral occurrences. The firstcomprehensive description of the geology in the area was written by Armstrong (1949). Hismemoir inc'ludes a geological map (Fort St. James) which covers NTS sheets 93K and 93N at a scale of6 miles to the inch. The northern part of the map area was first sys- tematically mapped (at a scale of 1:250 000) by Gabrielse ( 1975) who described rocks in the Fon Grahame maparea (94C. east half: Figure 9). The geology of the west half of the Fort Grahame sheet had been previously described by Roots (1954). The Halfway River sheet (94B) was mapped by Irish (1970) andlater in more detail by Thompson (1989). To the east. the Pine Pass sheet(930) was mapped at a scale of 1:250 000 by Muller (1961). Specificgeological studies within the projectarea havebeen carried out by Monger(1973. 1977a) and Monger and Paterson (1974)who examined Paleozoic rocks near Nina Lake. Monger and Ross (1971) and Rosb ancl Monger (1978) descrihed upper Paleozoic fusulinids froln the Nina Lake area. Meade (1975a.b. 1977) carried out adetailed examination of the Takla Group in the vicinity of Germansen Landing. Garnett (1978) provided a detaileddescription on the southern part of theHogem batholith which is situated immediately east of the study area. Preliminary results of the current program have been puhlished by Ferri andMelville (1988, 1989, 1990a. b,) ancl Ferri et al. (19XX. 1989). Geologic studies in nearby areas include a Ministry of Energy, Mines and PetroleumResources of British Columbia mapping project to the southeast, near Mount Figure 9. Location of published geologic maps in the vicinity of Milligan, which examined Tdkla Group rocks (Nelson the map area, (a) Muller and Tipper (1969). StNik i 19x5, 1989a, b and Slruikand Fuller Struik and Northcote 1991. 1992, 1993a. b). Struik and Northcote (1991) 19901, (1988). et d. (19Yl).Pohlerefo/.(1Y89).Taite(1989).(b)Armstrong(1Y49). recszntly completedmapping in thePine Pass area.Pre- (c) Muller (1961). (d) Gahrielse (1978). (e) Kuats (1954). (0 liminarymapping of theMcLeod Lake sheet was Irish (1970). Thumpson (1989). (g) Monger (1977b). (hl Nelson described by Struik (1989a. band 1990), Struik and Fuller el a/. (1991 j. ii) Nelson rf a/. (1992). (I) Nelson PI a/. (l993a. b). (l988),DevilleandStruik(1990),Pohlereta/.,(1989)and (k) Ferri Pt a/. (1992a. b). (1) Ferri ef a/. (1993a. b). (ml Garnett Taite (1989).Struik (1985) carriedout reconnaissance (1978) and in) Study area.

7 Plate 1. The old town site of Germansen,cu. 1890s. This location is 2 kilometres upstream from the mouth of the Germansen River. It was close to rich placer fields which were worked by large hydraulic operations. (Reproduced with permission from the British Columbia Archives and Records Service; catalogue number HP28531).

Plate 2. A hydraulic operation, probably along theGemansen River. These workings obtained their water through large wooden flumes or aqueducts. Numerous hydraulic operations were setup in the 1930s and the remains of several flumes can be found along the Germansen and South Germansen rivers. (Reproduced with permission from the British Columbia Archives and Records Service; catalogue number HP29400).

8 EXPLORATION HISTORY We would also like to thank the people in and around the towns of Manson Creek and Germansen Landing who The exploration heritage in the study area is domi- were helpful and madeour stay in the area pleasant. nated by placer gold prospecting(Plates 1 and 2). The Special mention goes to Don and Irene Gilliland of the M.mson Creek and Germansen Landing area has long been Gilliland Lodge where the project was based during the knownas an importantplacer gold producer in the summers of 1988 and 1989. We thank the Muller family of province. Gold was first discovered in the region in 1868 Germansen Landing for their help and friendship during and most of the rich deposits were mined out by the turn of the 1989 field season. the century (Armstrong. 1949). There was renewed inter- Fossils were identified by B.S.Nortord and M. J. est. in the placer fields during the depression years when Orchard of the Geological Suivey of Canada and by R. sweral operations were assembled capable of processing Ludvigsen. Potassium-argon age determinations were car- large quantities of gravel. Mining ceased with the outbreak ried out by J. Harakal of the University of British Colum- of the Second World War and since then most production bia. Uranium-lead dates were generated by D. Murphy, I. has been from small diggings. Gabites and J. Mortensen also of the University of British Hardrockprospecting was sporadicprior to con- Columbia. Apatite fission track analyses were provided by struction of the main roadinto the area in 1937 (Arm- D.S.Miller of the Rensselaer Institute. Geothermometry strong and Thurber, 1945). Increased accessibility and the calculations were carried out by Kim Bellefontaine on discovery of thePinchi mercury deposit led to further minerals kindly analyzed by Mitch Mihalynuk. Cartogra- exploration up to and just after the Second World War. phy was by MartinTaylor of the GeologicalSurvey Most of the significant showings along the Manson fault Branch. zone were discovered during this period. During the 1970s The writing of this manuscript was made much easier and80s exploration interestwas renewed with activity through thehelp of many colleagues at the Geological concentrated on the carbonate-hosted lead-zinc showings Survey Branch in Victoria and at the Geological Survey of nc’rth of Nina Lake and precious metaland sulphide occur- Canada in Vancouver. Geological concepts evolved from rences along the Manson fault zone. numerousand interesting discussions with JoAnne Nelson, Mitch Mihalynuk, Kim Bellefontaine, Bert Struik, Hugh Gahrielse, Andre Panteleyev and Chris Rees. The stratigraphy of North American Paleozoic rocks benefited ACKNOWLEDGMENTS from numerous discussions with A.B. Mawer of Cominco Ltd. andDunham Craig. John Newelland Brian Grant This final product of the Manson Creek project was provided excellent editorial comments on style and con- made possible by the hard work and thoughtful input from tent through the various versions of thismanuscript. many people over the years. Cheerful and competentassis- Mitch, Kim and JoAnne also read versions of this paper tance was given in the field by Neil R. Swift and Grant M. and provided very helpful and appreciated input. Special M.alensek (I 987). Ron L. Arksey (1988) and Jack Whittles mention goes to Bert Struik of the Geological Survey of and Mike Holmes (1989). A special mention is given to Canadawho sacrificed some spare time to critically SeanHorgan for his timelyassistance during the1988 review themanuscript andwhose suggestions helped field season. Logisticalsupport was provided by Gary improve the final product. All of the interpretive sections Arsenaulr, Allan Gilmour and Mike Fournier. within this paper are a ‘snap-shot’ of our ideas circa 1990. Special thanks goes out to Northern Mountain Heli- Newerinformation obtained by furthermapping to the of the study is copters, particularly the staff at the Mackenzie base. These northwest area only partially incorporated include pilots Brian Dougherty andJim Franklin who were into the descriptive pans of the paper. very patient and provided excellent service. We also thank Finally, the senior author thanks Kim Bellefontaine OkanaganHelicopters (now Canadian Helicopters) for for her needed and much appreciated support while writ- their help during the 1987 field season. ing this manuscript.

9 - LITHOLOGIC UNITS

ANCESTRAL NORTH AMERICAN is quite different. The Boulder Creek group is dominated CRATON by fine clastic rocks with lesser sandstone, limestone and amphibolite. These rocksbear little resemblance to the Rocks of NorthAmerican affinity belong to the coarse, thick-bedded feldspathic wackes and sandstones of Cassiar and Kootenay terranes which represent pieces of the Swannell Formation. Comparable thick sequences of displacedcontinental margin. In the map area North tine clastics within the Ingenika Group are found within Americanrocks aredominated by those of the Cassiar the Tsaydiz to Stelkuz section. This section also contains Terrane with only a small fault-hounded area of Kootenay the thick Espee Formation carbonate, which has no equiv- Terrane sediments in the southeast. alent in the Boulder Creek group. Furthermore the thinly hedded phyllites and limestones of the Tsaydiz Formation KO'OTENAY TERRANE are not present in the Boulder Creek succession. Only the Stelkuz Formation has similar sections of sandstone and BOIULDER CREEK GROUP limestone. However, the sandstones of the Stelkuz Forma- (informal, Proterozoic to Paleozoic ?) tion are much purer than those of the Boulder Creek group and the entire Stelkuz section is considerably thinner than A series of sandstones, impure quartzites, siltstones, the Boulder Creek section. argillites, marbles and minor amphibolite assigned to the Boulder Creek group are exposed along the creek of the Thecorrelation of BoulderCreek strata with the same name. Thesesediments are in fault contact with Kootenay Terrane is further substantiated, in part, by their surr<:)unding rocks of the Slide Mountainand Quesnel spatial relationship with other stratigraphic groups in the terranes. Good exposure extendsup to the Skeleton Moun- map area. Its position relative to otherrocks is very similar lain region. This unit also crops out along the ridges south to that of the Snowshoe Groupbetween Prince George and of L.ower Manson Lake and disappears beneath Quaterti- Barkerville (Struik. ;bid.) where it lies west of the Slide ary cover along Dunne Creek in the southeastern part of Mountain and Carihoo (Cassiar) terranes. The Snowshoe the map area. Group is flanked on thewest by the black phyllite unit The Boulder Creeh group fbrms an enigmatic pack- which is equivalent to the Slate Creek succession (lower age of strata exposed along the Manson fault zone. Arm- succession of the Takla Group). Sheared mafic and ultra- strong (1949) assigned them to the Wolverine Complex mafic pods of the Crooked amphibolite are found intermit- based on characteristics similar to rocks in the Wolverine tently along the contact hetween the black phyllite and the Snowshoe Group.The Crookedamphibolite is exposed Ran,te. Ferri andMelville (198X) and Ferri et rrl (1988) sporadically along this boundary from Clearwater to near placed these rocks within the Nina Creek group based on the presence of thin, discontinuous layers of siliciclastic Prince George(Struik, IY88a). It is part of the Slide rocks similar to those seen elsewhere in the Nina Creek Mountain Terrane and has been correlated with the Antler group of the area. Subsequent mapping in the Nina Lake Formation (Struik, ibid.), an equivalent of the Nina Creek area indicates that they are not characteristic lithologies of group. The Crooked amphibolite is also seen to sit struc- the Nina Creek group. hut rather form a unique lithologic turallyabove the Snowshoe Group in theQuesnel Lake pack.age. area (Rees, 1987). A very similar relationshipexists in the map area. Age and Correlation The Boulder Creek group is hounded on the west by the Slate Creek succession.This contactcontains pods of Lithologically, these rocks have the closest affinities MansonLakes ultramafics (equivalent to the Crooked with theIngenika Group. Thih is not only based on the amphibolite) which also sit structurally above the Boulder abundantamount of ciltstone,sandstone and impure Creek group. quartzite. hut also on the presence of amphibolite-grade The implications metamorphic mineral assemblages andpolyphase defor- of this are that the western margin of the Boulder Creek thrust fault which is mation that regionally are found only within the Ingenika group may he a termed theEureka thrustto the south (Struik, 1985). Group.The simplest interpretation is that theserocks Thrustfault relationships are seen betweenultramafic represent a fault sliver of lngenika Group incorporated in rocks and the Boulder Creek group, hut we believe (for the .Manson fault zone. This is consistent with structural reasons which will he discussed in a later section on the relationships seen to the south in the PinePass and Manson fault zone) that the western margin is now pan of McLeod Lake map arcas (L. C. Struik,personal communi- a strike-slip fault related to the Manson fault zone. cation, 1990). These tine-grainedclastic rocksand impure carbo- Lithology nate., are believed to represent pericratonicstrata (i.?., Kootenay Terrane) and to he equivalent to the Proterozoic The Boulder Creek group is characterized by grey- to Paleozoic(?) Snowshoe Group of the Barkerville Ter- greento green siltstones, silty phyllitesand phyllites rane (Struik. 1985, 1988aj.Although they havesim- which are thin to moderately bedded. Sequences of thin to ilarities with the Ingenika Group, the overall stratigraphy thickly bedded, grey to beige. very fine to fine-grained ~.

argillaceous sandstone, feldspathic sandstone or quartzite Within the map area Paleozoic carbonaterocks of the up to I00 metres thickoccur withinthese lithologies. Cassiar Terranewere initially placed within the Cache These sandstones are sometimes interlayered with thinly CreekGroup by Armstrong(1949) and Roots (1954), bedded grey-green phyllite to siltstone. Minor recrystal- though theynoted that some of theselimestones were lizedlimestone or marbleand amphibolite schist also older than typical Cache Creek carbonates. These authors occur within this package. alsorecognized Lower Cambrian quartzites and minor Impure quartzites and sandstones, which tend to be limestones but grouped them with theTenakihi Group, brown weathering, moderately to thickly bedded, and fine lngenikaGroup and the Wolverine Complex. Monger to medium grained, arewell exposed along Boulder Creek. (1973) and Monger and Paterson (1974) realized that all Theyare commonly cut by large (upto 1 metre thick) carbonates of this package were early Paleozoicin age and quartz-carbonate veins. Bedding, which is typically wavy, not part of the CacheCreek Group. Gabrielse (1975), is difficult to distinguish in these rocks and outcrops have working in the northern part of the map area, attempted to a massive appearance. separate the LowerCambrian units from rocks of Pro- Interlayered,thinly bedded siltstones, fine-grained terozoic age. He also noted the similarities of these rocks sandstones and phyllites occur along Skeleton Mountain. tolower Paleozoic rocks farther northin theCassiar Bedding in these lithologies is strongly planar. The silt- Mountains. Gabrielse, togetherwith Monger and Paterson, stones and shales are greenish grey to green in colour and believed the Mount Kison carbonates were younger than commonly crenulated. These clastic sequences give way Lower Cambrian. Economically these rocks are important northwestward to assemblagesdominated by grey-green to in that they contain significant carbonate-hosted lead-zinc- greenishphyllites with minor buff-weathering marble barite occurrences in the uppermost carbonate units. bands. Fem and Melville (1990a, b)applied formational and Greenish phyllites, grey to beige siltstones and minor group names fromthe Cassiar areato this package of rocks sandstonesare exposed south of Lower Manson Lake. due to their similarities with those of the Cassiar Moun- Bedding tends to be very fine and indistinct which, in the tains (Gabrielse, 1963; Nelson and Bradford, 1987, 1993, comer lithologies,may produce massive outcrops. The Table 2). Although these rocks have affinities to those of phyllites and siltstones have a layer-parallel fabric which the northern Cassiar Terrane, they are sufficiently different is cut by a later upright cleavage causing these rocks to to warrant alocal nomenclature. Furthermore this Pal- weather into rod-shaped fragments. The phyllitesbecome eozoic succession is essentially restricted to the Manson increasingly metamorphosed to the southwest, displaying Creek and Germansen Landing area. It is truncated to the a schistose fabric andcontaining porphyroblasts of biotite, north and south by sections of the Wolverine fault zone. chloritoid, garnet, tourmaline and staurolite. Dueto itsrestricted extent and unique character, new Minorgrey, cream or buff-weathering, mediumto names have been proposed for many of these units. These coarselycrystalline marbleswith indistinct beddingare are, in ascending order, the Razorback group, Echo Lake also found in the Boulder Creek group. They form layers group,Otter Lakes group, and Big Creek group upto several metres thick within both the phyllitic (Figure 13). sequences southwest of SkeletonMountain and the clastic sequences along Boulder Creek. INGENIKA GROUP (Upper Proterozoic) Asection of amphibolite up to IO metres thick is exposed along Boulder Creek. It is characterized by dark Upper Proterozoic sediments in the map area were green,fine to medium-grained crystalline amphibole in first described by Armstrong(1949) who carried out a association with chlorite and feldspar, sometimes segre- cursory examination of these rocks and placed all of them gated to produce a gneissic texture. within the Wolverine Complex.Roots (1954). working north of thestudy area,further subdivided these Pro- terozoicsediments into the Tenakihi Group, Ingenika CASSIAR TERRANE Group and Wolverine Complex. The lastwas reserved for Proterozoic to Permian rift-related and miogeoclinal thestrongly metamorphosed rocks where stratigraphic rocks of the Cassiar Terrane are dominated by siliciclastic correlations with less metamorphosed strata are tenuous. rocks with carbonates becoming more abundant toward BothArmstrong and Roots included Lower Cambrian the topof the sequence. Theserocks are represented by the strata within these units. Proterozoic IngenikaGroup, the LowerCambrian Atan Gabrielse (1975). working in the study area and in the Group, the Cambrian to Ordovician(?) Razorback group, Swannell Ranges to the north, found Roots’ (1954) two- the Ordovician to Lower Devonian Echo Lake group, the fold subdivision of the Proterozoic sediments unworkable Middle Devonian Otter Lakes group and the Upper Devo- inthat there islittle distinctionbetween the Tenakihi nian to Permian Big Creek group. The lower parts of the Groupand the Ingenika Group, save for metamorphic Proterozoicsuccession contain regional metamorphic grade. Gabrielse therefore referred to these rocks as the culminationswhich are termed the Wolverine (Meta- IngenikaGroup and recognized afour-fold subdivision morphic) Complex. This sequenceof strata is very similar similar to that used here. He did not map out the various to North American stratigraphy described in the northern units of the Ingenika Group and he also included parts of CassiarTerrane of British Columbia (Gabrielse, 1963; the Lower Cambrian succession with the uppermost Inge- Nelson and Bradford, 1987, 1993; see Table 2). nika Group.

12 TABLE 2 CORRELATION CHART OF NORTH AMERICAN PALEOZOIC STRATIGRAPHY WITHIN THE STUDY AREA AND PALEOZOIC STRATA SEEN ELSEWHERE ALONG THE CORDILLERA.

CASSIAR OMINECA MCLEOD LAKE CARIB00 MOUNTAINS MOUNTAINS(East of McLeod MOUNTAINS Cake Fault) (Gabtielse, 1963,' Nelson and Bradford; 1993; Nelson et al (This sfudfl (Stmik. 1989a, 1990) (SfmlX 1988a) 1988) Aississippian(?) chert, argillite tuff, sandstone Sugar Limestone to Permian Lower Big Creek group slate, argillite, Greenberry tlississippian to tuff(?), dolostone at Formation Earn Group

~ IGuyet Formation Jpper Devonian !- - . base 9 c liddle Devonian Waverly McDame Group Otter Lakes group dolostone 5 Formation e L limestone, 9 dolostone, tj .ower Devonian Tapioca Sandstone, quartzose to Silurian Sandpile Group Echo Lake group 3 Un-named Units dolostone, 5

Cambrian to Razorback Sand ile Group I Ordovician PRoad River group Grou heCreek KechikaGroup I Formalion Mt. Kison MuralFormation a RosellaFormation Lower 3 tc Cambrian e Midas Formation BoyaFormalion e 1 quartzite Yanks Peak 1 Formation

M~~~~ and Gabrielse (1978) proposed a four-fold sion in the southern pans of the map area is represented by subdivision for the lngenika Group (see Table 3) based on the lower parts of the Ingenika Group. detailed stratigraphic-work inthe northern part of the The IngenikaGroup is predominantly a clastic Omineca Mountains. Theydivided the group into four sequence with lesser carbonateand is in excess of 3.5 formations, in ascending order, theSwannell, Tsaydiz, kilometres thick in the study area (Figures 5, IO and I I). Espee and Stelkuz formations. All formations of the Ingenika Group arerecognized in the Proterozoic sediments in the map area can be traced map area and are compositionally very similar to the type directly into lithologies underlying the Swannell Ranges to area. The Swannell Formation is composed of sandstone, the north and are correlated with the lngenika Group as feldspathic wacke, slate and minor carbonate; the Tsaydiz proposed by Mansy and Gabrielse (1978). Formation is made up of slate, carbonate and lesser sand- A continuoussection of the lngenika Group is stone; The Espee Formation is a thick carbonate sequence er.posed between the Omineca and Osilinka rivers, where and the Stelkuz Formation is predominantlysandstone, all four formations canbe traced for a distance of over 30 slate and lesser limestone. kilometres. In thesouthern part of the maparea, near Ingenika Group rocks east of the Wolverine fault Granite Creek,only a small fault sliver ofthe upper part of zone in the southernpart of the maparea have been the lngenika Group is preserved. The hulk of the succes- subdivided into four units: impure metaquartzite and schist

13 Fj...... INGENIKA GROUP .. ipperProterozoic ""

Stelkuz Formotion ------

Espee Formotion

Tsaydiz Formation

""" w"""

_"" .. Pisp ...... Swanneli ...... ~....~ ...: ...... Formation ,' , ,' .. """""_

middle ...... ,. .

""~~ .,...... """"_" """ lower ...... ""_ ...... """ ...... ""_ ...... base not exposed Limestone Calcareous shale Dolomite 0Feldspathic wackc Sandy dolomite 0Orthoquartrite Siltstone ~mpurequartzite, 0 sandstone r"---I Shale

Figure IO. Stratigraphic column ofthe lngenika Group in the Figure 11. Stratigraphic column of the lower Ingenika Group vicinity of the Osilinka River. in the southern pan of the map area.

14 (Pirq); paragneiss and schist (Pisp); paragneiss, schist and Within units Pia and Pipi, the dominant exposed rock intrusive (Pipi); andamphibolite and calcsilicate gneiss type is pegmatite and granodiorite, which typically con- (Pia). Accuratecorrelation of theseunits with Ingenika stitute 70% or more of total outcrop (Plate 3). Metasedi- rocks in the northern part of the map is not possible. This ments may he underrepresented as theytend to form is due, primarily, to the inability to trace these units con- recessive exposures. Compositionally units Pisp and Pipi tinuouslynorthward into knownstratigraphy. This are very similarand are differentiatedprimarily by the inability to correlate units from south to north may also be predominance of pegmatite and granodiorite in the latter. a function of metamorphic grade. lngenikarocks in the The contacts of unit Pipi arethus subjective. A more southern pan of the map area are at considerably higher detaileddescription of theintrusive rocks is given in a grade than most of the rocks to the north and may appear later section. as different units. Most rocks in the south are at sillimanite The northwest margin of unit Pipi is marked by a grade or higher and composed of coarsely crystalline sch- seriesof steep,northeast-facing slopes. Within it, the ists and paragneisses. Most rocks in the northern part of ridges are fairly straightand consistently trend north- the map area are between chlorite and garnet grade. The easterly, parallel to the dominant foliation in the gra- lithologies are phyllites, schists and metagrits with coarse nodiorites and pegmatites. This supports the inference that schlsts and paragneisses restricted to the area along the much of this area is underlain by these rock types. Wolverine Range (within the sillimanite isograd). In thisreport the terms‘Wolverine Complex’ or Impure metaquartzite, schist and paragneiss of units ‘Wolverine Metamorphic Complex’ refer to high-grade Pisq and Pisp are broadly similar to the Swannell Forma- metamorphic rocks (abovesillimanite grade) or meta- tion and may he high-grade equivalents of this formation. morphic culminations found within the Wolverine Range Amphibolite and calcsilicate gneiss of unit Pia have no and immediately along strike with the Wolverine Range. correlatives in the Swannell Formation and may represent a lower unit of the lngenika Group. Thus lngenika Group Age and Correlation rocks in the southern part of the maparea, east of the Wdverine fault zone, may represent the lowermost pans The lngenika Group is pan of the Upper Proterozoic of this group.Their exposure in this area is related to Windermere Supergroup, which extends along the entire displacement on the fault Lone. length of theCanadian Cordillera(Figure 12). This

Platt. 3. Outline of metasedimentary rdft within granodiorites of unit Pipi near Mount Bison. This picture exemplifies the relationship hctKecn intrusive material and metascdiments within the high grade gneissm nf the lngenika Group in the Wolverine Range. Geologist standing lower right of sedimentary raft for scale.

15 sequence of strata is lithologically similar to otherWinder- (Gabrielse,1975; Evenchick, 1988). These rocks are mere rocks located south and north of thestudy area. floored by 728 Ma granitic basement (Evenchick, ibid.) Regional correlations of the Ingenika Group have been and can be subdivided into three units; a lower clastic unit established by Mansy and Gahrielse (1978) and Gabrielse of phyllite, siltstone, feldspathic quartzite, diamictite and and Campbell (1991) and a detailed account will not be minor carbonate; a middle slate and carbonate unit with attempted here. Table 3 is a correlation chart of the Inge- lesserquartzite and conglomerate;and an upper clastic nikaGroup and other Upper Proterozoic stratigraphy unit of argillite, quartzite and siltstone. McMechan (1987) within the Cassiar Terrane and North American craton. It documented a similar succession south of the Peace River, is modified from similar chartspublished by these authors. with the only difference being a more developed middle Rocks in the study area, and in the Cassiar Moun- carbonate unit. It seems likely that this middle carbonate tains, can be correlated directly with units in the Cariboo unit is equivalent to the Espee Formation, and the Swan- Mountains(Struik, 1988a). The thick quartzand feld- nell and Tsaydiz formations are correlative with the lower unit and the Stelkuz Formation equivalentto the upper part spathic wackes of the Swannell Formation are equivalent of the Misinchinka Group. to similar lithologies in the Kaza Group. The succeeding slates and sandstones of the Isaac Formation, carbonates Amphibolite and calcsilicate gneiss of unit Pia have of the Cunningham Formation and slates, siltstones and no lower grade correlatives within the Ingenika Group of sandstones of the Yankee Belle Formation are equivalent the maparea. They disappear to thenorthwest as they to theTsaydiz, Espee and Stelkuz formations,respectively. plunge below metasediments of unit Pipi along a crudely Correlations withProterozoic sedimentsacross the defined F, antiform. These gneisses may be correlatives of northern Rocky MountainTrench, aresomewhat more amphibolite schist and marble units which sit above 1.85 tenuous due to apparent facieschanges. Directly northwest Gabasement gneiss in theSifton Ranges (Evenchick, where amphibolites and marbles are associatedwith of the map area, within the Rocky Mountains, the Upper ibid.) abundant metaquartzite which is lacking in the Wolverine Proterozoic isrepresented bythe Misinchinka Group Range.

Amphibolite and Calcsilicate Gneiss (Pia) Nearthe Manson River, the lngenikaGroup is characterized by the presence of marbles and calcsilicate gneisses associated with amphibolite gneiss. These rocks are thought to be at the lowest structural and stratigraphic levelwithin the lngenika Group. Theyterminate northwestward against a large body of granodiorite. Themarbles are grey tocream incolour, coarsely crystallineand contain phlogopite, garnet,diopside and calcite. Theyform bands 0.1 to 2 metresthick and are interlayered with calcsilicate rocks. Calcsilicate gneisses arepredominantly diopside and plagioclase with lesser garnet andcalcite. They are dark green to greenand coarsely crystalline. These unitstypically occur in sections up to 10 or 15 metres thick. Near Munro Creek, a marble- calcsilicate band some 200 metres thick can be traced for over 10 kilometres. Its southern extension is lost due to poor exposure. Amphibolite gneiss is prominent in this unit, making up to 30% of exposures southeast of the Manson River. This gneiss is very similar to that within units Pisp and Pipi.

Paragneiss, Schist and Infrusive (Pipi) This unit occupies thenorthern part of the Wolverine Range east of Bisson Mountain with its southern termination against a large body of granodiorite.Exposure is excellent in theBison Mountain area and diminishes somewhat to the southeast. Paragneisses and schists of this unit are similar to thosein unit Pisp. Dark brown, rusty weathering sillimanite-garnet-quartz-feldspar-muscovite-bio!itesch- Figure 12. Distribution of Windemere stratigraphy along the ists occur in layers 0.1 to 1 metre thick. They are coarsely Canadian Cordillera. crystalline and sometimes slightly chloritized.

16 TABLE 3 CORRELATION DIAGRAM OF INGENIKA GROUP STRATA WITH OTHER PROTEROZOIC SEQUENCES IN THE CANADIAN CORDILLERA.

CASSIAR OMiNECA CARIB00 SELKIHK NORTHERN CENTRAL ROCKI MOUNTAINS MOUNTAINS MOUNTAINS ROCKY MOUNTAINSMOUNTAiNS MOUNTAINS (Mansy and (Mansyand (Stnu4 i988a) (Poulkm and (Gabfielse, i97Z (CampbeKelal, Gabnetse, 1978; Gabnetse, i978; Simon& i98) McMechan, i987,' i973) I Evenchick, i988) I ThsSludyj I I Yanks Peak Alan Group FormationHamill Group I Gog Group Gog Group Yankee Eeile UpperClastic Formation Formation I PEspee Cunnigham Carbonate Formation Formation Division Tsaydiz Formation F 6 6 4 c c Swanneil E Formation .-c

? Group I Wolverine 1 1 bbCrystalline Crystalline L Basement 1 Easement

Dark grey to dark grey-browngneisses are inter- 25% whitepotassic and calcic feldspar. The least laryered with the schists in sequences 0. I to 2 metres thick. deformed of these sequences appear to be metamorphosed They tend to be quartz andfeldspar rich (upto 80% feldspathic to quartz wackes(grits). The metaquartzites ca,mbined) with garnet and sillimanite as the only meta- are similar in appearance but contain less than 5% feldspar mmnrphic accessory minerals. and mica. Amphibolitegneiss is composed of garnet,quartz, Grey-green diopside-bearing calcsilicate gneisses are bi'atite,plagioclase and amphibole, with the amphibole present in this unit. They are massively layered, coarsely cmtent varying from 20 to almost 100%. These gneisses crystalline and contain up to SO% diopside. ax oftenthickly layered and coarsely to very coarsely The stronglymetamorphosed basal portions of this crystalline. Hornblende typically exhibits low-grade retro- unit are injected by several generations of pegmatitic sills, gression to actinolite. dikes and related granodioritic and granitic bodies comprising over SO% of the outcrop. Many of the pegmatitic Paragnei.w and Schist (Pisp) sills, primarily the thinner ones, are folded or boudinaged, but the larger pegmatite bodies are foliated only on their This unit is exposed within the Wolverine Ranges in margins. Later generations of pegmatite crosscut the folia- of the study area. Its exact thickness is the southern part tion and are undeformed. These rocks are also described in unknown but it is at least 1 kilometre thick. It is charac- more detail under Wolverine Range intrusions. tel-ized byquartzofeldspathic paragneiss and quartz- feldspar-micaschist with lessermicaceous quartzite. Minor constituents are calcsilicate gneiss and amphibolite. Impure Metaquartzite (Pisq) The schists are composedprimarily of medium to UnitPisq comprises micaceous metaquartzite, coarse-grained muscovite and biotite which may be chlo- quartmnica schist, metaquartzite and minor amphibolite. ritized. Accessory minerals are commonly garnet and sil- It is poorly exposed al~~ngthe west flank of the Wolverine limanite with rare kyanite. Range in the southern part of the map area. It varies in Thequartzofeldspathic paragneisses are typically thickness from some 500 metresnear Granite Creek to grey to grey-brown, medium to very coarsely crystalline well over 1 kilometre north of the mouth of Ciarelli Creek. and formlayers IO centimetresto 1 metrethick. They Its lowercontact is gradational, and placed at the first occur inintervals up to IO metres thick and are inter- thick sequence of quartz-rich layers. Its upper contact is layered with the schists.They commonly containup to cut by the Wolverine fault zone.

17 Themicaceous or impuremetaquartzite isgrey- part, to the rather poor exposure, but is related more to brown and contains 5 to 10% micaceous material and less displacement on the Wolverine fault zone. than 5% feldspar. It is fine to medium grained andpresent in layers 10 to 50 centimetres thick in sequences up to 5 Lithology: A poorly exposed, apparently continuous, metres thick. These quartzose bands are interlayered with relativelyunmetamorphosed sequence of the Swannell silver to greyishsilver-brown quartz-muscovite-biotite Formationcrops out on Breeze Peak, west of the schist IO centimetres to I metre thick. These schists may Wolverine fault zone. A threefold subdivision of the for- contain considerable quartzand are commonly chloritized. mationis possible on the basis of these exposures In generalthe upper part of the unit contains thicker (Figure IO). The ability to subdivide the Swannell Forma- sequences of impure metaquartzites. tion in this area is based primarily on the presence of a The unit is intruded by sills and dikes of pegmatite thick succession of feldspathic and quartz wackes forming very similar to those within units Pisp and Pipi (Plate 4). the middle unit. This area is also complicated by folding These bodies are small (less than a few metres thick) and such that lithologies assigned to the lower part of the constitute less than 5% of the unit. Swannell Formation to the northeast may be part of the middle unit. The subdivisions proposed here are broadly similar to those described by Mansy and Gabrielse (1978) Swannell Formation in the Swannell Ranges. The SwannellFormation is areally the most extensive In the Breeze Peak area, the Swannell Formation is of the Ingenika Group, occupying roughly the eastern thirdupwards of 2 kilometres thick andis tectonically thickened of the northernpart of the map area. The thickness is to the east. Rocks east of the Wolverine fault zone repre- difficult to deduce dueto polyphase deformation and lack sent lower parts of the formation and the relationship of of continuous outcrop. It is at least 2 kilometres thick and theserocks to units Pisq andPisp is not known with is tectonically thickened to the east. The basal parts of the certainty. In the northern part of the map area, schists and formationare polydeformed, metamorphosed to sil- paragneisses in theWolverine Rangeappear similar to limanitegrade and intruded by pegmatite and related those of unit Pisp. This similarity may simply reflect the granodiorite. similar metamorphic grade (sillimanite) of each package No continuous stratigraphic sequence of the Swannell which may mask original differences. Yet it appears that Formation is exposed within the map area. This is due, in metamorphicgrade is generally related to stratigraphic

Plate 4. A pegmatitic sill 2 metres thick within paragneisses and schists of the Ingenika Group. This relationship is typical of unit Pisp and units Pipi and Pia where intrusive material constitutes up to 50% or more of the exposure.

18 level (see chapter on Metamorphism,and Gabrielse, 1975) lbaydiz Formation and, if so. these two units may be equivalent. The Tsaydiz Formation is poorlyexposed and has In the Breeze Peak area the lowest member is at least been inferred throughout most of the northern pan of the 1 kilometre thick, though it appears substantially thicker map area. In the south, it is exposed near Granite Creek. In dm: to polyphasedeformation. Here relatively this area it crops out in the core of an anticline outlined by unrnetamorphosed lithologies are exposed and are com- theEspee Formation and in theupper plate of asmall por,edprimarily of thin to thicklybedded, very fine to thrust fault. medium-grained quartz and feldspathic wdckes. The feld- The lower contact of the Tsaydiz Formation is placed spar content is typicallyless than 15%. Generally,the at the top of the highest resistant layer in the Swannell claitics of this unit are quartz rich in comparison to the Formation. The thickness of the formation varies from 300 lithologies of the middle unit. Subordinate lithologies are metresnear the OminecaRiver to approximately 750 very fine grainedimpure sandstones, siltstones, grey to metres south of the Osilinka River where it may be exag- whitemarble (several metres thick), greenish slates and gerated by tectonism. green to grey phyllite and schist. Phyllite and schist form In the northeastern corner of the map area the Tsaydiz sequences up to 3 metres thick. These rocks become more Formation is poorly exposed and isinferred from the strongly metamorphosed to the east and the pelitic mem- presenceof the Espee Formation (see underEspee hers are represented by garnet-biotite-feldspar-quartz sch- Formation). ists. North of the Osilinka River, near Edmunds Creek, staurolite and metamorphic tourmaline are present as large Lithology: TheTsaydiz Formation is typified by porphyroblasts up to 2 centimetres long. light greenish grey to grey, crenulated slates and phyllites that are commonly interlayered with thinly bedded, buff- Along the Wolverine Range. basal rocks of this unit weathering limestone t11 argillaceous limestone (Plate 6). are metamorphosed to sillimanite grade. They are coarsely Lessersiltstones, quartz and feldspathic wackes and crystalline schists, micaceous quartzites, diopside-bearing recrystallizedbrown-weathering, grey limestone layers, calcsilicate,and quartzofeldspathic paragneisses. These I to 5 metres thick, are also present. Quartzose layers are roclks areinjected by several generations of pegmatitic thin to massively bedded and are commonly interlayered sill!;, dikes and related granndioritic material (see section on Wolverine Range intrusions). Themiddle member of the SwannellFormation, some 300 to 400 metres thick, is characterized by massive beds (I to IO metres thick) of feldspathic wacke (Plate 5). These wackes are very coarse grained and approach granule conglomerates in some areas. They contain up to 30% chalky white feldspar crystal clasts and the quartz has a characteristicblue to purplish opalescence which disappears as the garnet isograd is approached. Greenish grey to silveryslate and phyllite, tineto coarse-grained quartz wackes to sandstones and their higher grade metamorphic equivalents make up the remainder of this unit. The upper member is roughly 300 metres thick, although, in the vicinity of Henschel Creek, thick feldspathic and quartz wackes similar to the middle member outcrop immediately below the Tsaydiz Formation, making the upper member no more than 50 metres thick. This member is characterized by massivelybedded, brown- weathering. fine to coarse-grained,impure quartzite and sandstone. These rocks may grade into, or be interbedded with. siltstones and slates. Of lesser importance are dark greyto greenish grey slates, phyllites and feldspathic wackes. This member is metamorphosed to amphibolite grade in thenortheast and the schistose rocks contain garnet and tourmaline its accessory minerals.

The quartzite is typicallyimpure and contains 5 to 10%;.micaceous material and less than S% feldspar. The sandstonecommonly contains IO to 1.5% feldspar. The quartzose layers are IO to SO centimetres thick and found Plate 5. Coarse quartz to feldspathic wacke(grit) of the Swannell in sequences up to 5 metresthick. Interbedded pelitic Formation on the west side of BreezePeak. These beds are layers are IO to 100 centimetres thickand may form massive and typically show few internal features. Quartz grains continuous sections up to S metres thick. commonly display a blue-purple opalescence.

19 withthin phyllite or slatebands. Limestonesare more Lithology: The Espee carbonates are white to grey, prevalent toward the base of the formation. buff to tan-weathering limestones to dolomitic limestones whichare moderately to thinly beddedand typically Espee Formation recrystallized to a coarse marble. These rocksrarely break along bedding but rather along joints or a cleavage pro- TheEspee Formation is a cliff-forming carbonate duced by thepreferential alignment of calcitecrystals. unit which ranges from 200 to over 400 metres in thick- Bedding, when seen, is typically markedby alternating ness. It is easily traced through the northern part of the light and dark grey bands. map area and is structurally repeated in the vicinity of Granite Creek. It underlies Mount Dewar and forms spec- The lower contactof the formation is rarely exposed tacular cliffs east of Mount Kison.It is one of several but whereobserved, there is a transitionalzone where excellent marker horizons in the stratigraphic succession interlayered slates and limestones of the Tsaydiz Forma- of the map area (Plate 7). tion give way to the more massive limestoneof the Espee Formation. Similarly, at the upper contactwith the Stelkuz A thick marble unit is present in the northeast comer Formation, buff-weathering, thickly layered Espee lime- of the map area and isassigned to the Espee Formation. It stonesare interlayeredwith green slates of theStelkuz is in theorder of 300 to 350 metres thick(based on Formation across a zone some 50 metres thick. structural cross-sections) and is assumed to be upright. A carbonate of this thickness is not typical of the Swannell Stelkuz Formation Formation (see Mansy and Gabrielse, 1978). The unit can be traced regionally intoa carbonate which is undoubtedly The Stelkuz Formation is well exposed in the north- the EspeeFormation (see Gabrielse, 1975). This carbonate ern partof the study area, particularly below Mount Kison. is found within middle amphibolite facies metamorphic Exposuresare also presentwithin thefold pair along rocks which are not typical of the Espee Formation in the Mount Brown. In the southeast, this formation forms good map area. Gabrielse(ibid.) also shows the Espee carbonate outcrops along Granite Creek. situated above garnet grade metamorphism in the Butler Lithology: The Stelkuz Formation iscomposed of Range. approximately 400 to 500 metres of green to grey slate and siltstone, brown to grey impure quartzite and sandstone with minor dolomitic limestone. Slate and siltstone predominate in the lower partof the formation whereas sandstone, which is characteristically fine grained and planar bedded, becomes predominant toward the top. A moderately bedded, brown to tamweathering dolostoneunit, 5 to IO metres thick, locally occurs approximately 100 metres below the upper contact of the formation. In the Mount Kisonarea this carbonate can be traced for several kilometres. The upper contact of the Stelkuz Formation appears to be conformable with the succeeding Atan Group. The upper part of the Stelkuz Formation contains a coarsening upward sequence up to 100 metres thick, in which the amount of sandstone increases toward the top of the for- mationwhere thickly bedded,coarse-grained, impure quartzites, light grey to grey in colour, are very similar to basal Atan Group quartzites (Plate 8). Typically though, Stelkuzquartzites are impure and lack the glassy appearance of Atan orthoquartzites. The topof the Stelkuz Formation (and of the Ingenika Group) is placed at the base of the first thick (greater than 2 metres) sequence of white to light grey orthoquartzite. Thin layers (0.5 metre or less) of light-coloured orthoquartzites occur below this contact, within the impure quartzites. The contactrelation- ship is best exposed on thenortheast face of Mount Kison.

ATAN GROUP (Lower Cambrian)

Plate 6. Finely interlayered calcareous shale and limestoneof the Orthoquartzites, siltstones, shales, sandstones and a Tsaydiz Formation as seen along Henschel Creek. These rocks thickcarbonate unit abovethe StelkuzFormation are are interlayered with thicker sequences of shale and limestone. assigned to the Atan Group. This is based on the striking These recessive lithologies account for the poor exposure of this resemblance of thesestrata to lithologies of equivalent unit. composition, age and stratigraphic position described by

20 Plate 7. A view to the south fwm near Mount Brown, showing the excellent cliff-forming nature of Espee carbonates. These rocks dip moderately to the southwest.

Fritz (1980) in the Cassiar Mountains. In the Germansen Landing-Manson Creek area theAtan Group has been informallysubdivided into the lower, Mount Brown k quartziteofand composed shale sandstone,orthoquartzite, siltstone, and a succeeding thick carbonate assigned to the Mount Kison limestone (Figure 13). This groupof rocks is confined to the northern pan of the area and can be traced discontinuouslyfrom Blue Lake to theOsilinka River (Figure 7). The MountBrown and Mount Kison successions were originally assigned the rank of informal formations (Ferri et ul., 1992a. b: Ferri et a/.. 1993a. b) Because the current data on these units do not satisfy the strict require- ments for designation as formal formations, it is now felt that lithicmodifiers would better serve to indicatethe informal nature of these units.

Age and Correlation Only one fossil locality was found within this group (Appendix I); it is an archaeocyathid-hearinglimestone , within theMount Kison limestone.Gabrielse (1975) also i noted archaeocydthids in limestone lenses of the Mount Plate 8. Massive to thickly bedded impure quartzites and sand- Brown quartzite(?) south of the Osilinka River. stones of theuppermost Stelkur Formationat the top ofMount Correlations of thisgroup with similarlynamed Ki:ron.These pass upwardsinto orthoquartzites of theMount lithologies in the Cassiararea arestraightforward (see Bmwn quartzite 50 metres to the west. Table 2; Gahrielse. 1963; Nelsonand Bradford, 1987,

21 1993; Fritz, 1978, 1980). Quartzites, siltstones and shales of theBoya Formation are correlatives of theMount /&- Brown quartzite and carbonates of the Rosella Formation are equivalent to the Mount Kison limestone. Inthe Carihoo Mountains, quartzites of the Yanks Big Creek group PeakFormation and shalesto siltstones of the Midas (Upper Devonion to Lower Permian) Formation are probable correlatives of the Mount Brown quartzite(Struik, 1988aj. Thesucceeding limestone and dolostones of the Mural Formation are equivalent to the Mount Kison limestone. In the McLeod Lake area Struik(1989a. b), describes Lower Cambrian strata immediately east of the McLeod Lake fault. These interlayeredquartzites and dolostones appear grossly similar to the Atan Group but share more similarities with Lower Cambrian strata eastof the Rocky Mountain Trench. Otter Lakes group (Middle Devonian) The AtanGroup in the study area sharessome affinities with Lower Cambrian strata across the northern Rocky MountainTrench (Gabrielse, 1975, McMechan, 1987, Thompson, 1989) but is by no means directly correlative tothem. Directly northeast of thestudy area, Gabrielse (1975) describesa thick succession ofquartzitic sandstones, siltstones,shales and minor carbonates, the base of which is not exposed. To the southeast of the map Echo Lake group areaLower Cambrian strata are assigned to the Gog (Ordovician to Group.The quartzites, shales and siltstones of the Lower Devonian) McNaughtonFormation and the succeeding dolomitic sandstones, shales, and quartzites of the Mural Formation are probable correlatives of the Mount Brown quartzite and Mount Kison limestone, respectively.

Mount Brown Quartzite (Informal, Lower Cambrian) The Mount Brown quartzite varies in thickness from 200 metres northeast of Echo Lake to upwards of 375 Razorback group metres near Blue Lake. It is best exposed in the Mount ornbrian to ? Ordovi Kisonarea with relatively good outcrops south of Henschel Creek and along Mount Brown. Lithology: Thesuccession is characterizedby a white,grey, beige or brown, massiveto thicklybedded (Lower orthoquartzite, IO to 30 metres thick, at the base (Plate 9). Cambrian) It is typically fine to medium grained, hut thin beds of quartz-granule conglomerate are also present. This basal unit is very distinct and an excellent marker. Thin to moderately bedded olive-green to grey siltstone,shale and beigeto tan, very fineto fine-grained sandstone comprise the remainder of the sequence. Typ- Limestone ically thesandstone makes up lessthan 30% of the sequence, although sections of sandstone and quartziteup Oolmomite Shale to 10 metres thick occur in the upper pan. These massive Sandy dolomite Orthoquartzite sandstones occasionally contain vertical (Skolithus?) and bedding-parallel burrows. The basal shales may also con- Argillaceous Calcareous rhole limestone tain tiny porphyroblasts of chloritoid. Feisic luff Sandstane/wacke I Mount Kison Limestone (Informal, Lower Cambrian) Figure 13. Stratigraphic column of Paleozoic stratigraphy as TheMount Kison limestoneis best exposed near deduced in the northem part of the map sheet. MountKison, for which it is named. It is an excellent marker and can be easilytraced on air photographs. .It forms good outcrops south of Henschel Creek and is well exposed along Flegel Creek. On outcrop scale thisunit can

22 be (confused with carbonates of the lower Echo Lake group Lithology: The Mount Kison limestone is composed ancl the Espee Formation. Echo Lake carbonates generally of approximately 200 to 230 metres of limestone and rare contain quartz replacement and mottly or fenestral dolomi- dolomite(Plate IO). The basal part of the succession tization not seen in theMount Kison limestone.Espee comprises 20 to SO metres of dark grey to grey, thin- carbonates contain areas of coarse-grained dolomitization beddedand platy, finely crystalline limestone and ancl generally are more recrystallized than limestones of argillaceous limestone. This platy limestone is succeed by theMount Kison sequence. The EspeeFormation also approximately 150 to 180 metres of massive,thick- teds to be morethinly bedded than the Mount Kison bedded,fine to coarselycrystalline limestone and rare limestone. dolomite. Bedding in the upper part is outlined by thin, discontinuous to wispy argillaceouslayers less than a metre long. Horizonsof oolites, which may be silicified in the lower part of the section,are very rare.Archae- ocyathids were found in this sequence immediately west of Mount Brown. The lower contact of the Mount Kison limestone is transitional with the Mount Brown quartzite oYer a distance of approximately .5 metres; uppermost Mount Brown shales are succeeded by brown-weathering, nodular limestone and basal Mount Kison limestones.

RAZORBACKGROUP (Informal, Middle Cambrian to Ordovician?) The Razorback group is a poorly exposed sequence Plate 9. Highly resistant, white 10 greyorthoquartrites of the of argillaceouslimestone and shaleapproximately 75 basal Mount Brown quart7.ite east of Henschel Creek. Thisunit is metres thick. Due to its recessive nature, only a handful of one of several excellent marker horizons within the sedimentary outcrops were mapped in the northern part of the study succession in the study area. area. This unit was inferred throughout most of the north-

Plate IO. This picture shaws the cliff-forming nature of the Mount Kison limestone as seen north of Mount Kison. This unit can be easily traced on air photos as it is the first major carbonate above the Espee Formation. The recessive slope between it and the Echo Lakc: group to the west, is underlain by the Razorback group.

23 ern part of the area by the recessive slope between the The relative thinness of the Razorback group and the Mount Kison limestone and the Echo Lake group. Itsbest thick succession of younger carbonate rocks, reflects their exposure occurs on a ridge running east from Razorback probably position near the platformal facies of the carbo- Mountain.It also outcropsalong the ridge south of nate belt (see Echo Lake group). The trilobite assemblage Henschel Creek and in the vicinity of Mount Kison. fromthe Razorback group suggests a slope setting (R. Ludvigsen, personal communication, 1993). Ferriand Melville (1990a, b) originallyassigned rocks of the Razorback group to the Kechika and Road South of the map area, thetime-equivalent of the River groups based primarily on stratigraphic position of Razorback group is the DomeCreek Formation of the these argillaceousunits between carbonates that were very Cariboo Group (Struik. 1988,; Table 2). This unit is rela- similarto the RosellaFormation and SandpileGroup. tivelythin (less than SO metres)and is dominantly They obtained fossil data from calcareousshales originally argillaceous. believed to be part of the upper section of the Razorback Middle Cambrian strataof similar thickness and com- group indicating an Early Silurian age. These shales are position are present east of the northern Rocky Mountain now believed to be part of the lower Echo Lake group. Trench in the middle part of the Kechika Trough (Fritz et a/., 1991). Kechika Group strata sit above the Middle Age and Correlation Cambrian succession andreach thicknessesupwards of IS00 metres in the centre of the basin (Cecile and Norford, LowerMiddle Cambrian trilobites have been 1979). This suggests a different depositional environment recovered from the uppermost IO metres of the Razorback forsimilar aged strata in the Germansen Landingarea. groupat Razorback Mountain (A.B. Mawer, R. Lud- Alternatively this may indicate that Kechika-like strata are vigsen, personal communication, 1993; Appendix I). This missing in the Germansen Landing area or are a highly suggests that the bulk of the Razorback group at Razor- condensed sequence. back Mountain is Middle Cambrian in age. To the northwest, along the Osilinka River and Wasi Creek, Ferri efal., (1992a, b 1993a. b) recovered Early to Middle Ordovician Lithology graptolites from argillaceous horizons thought to be equiv- In the Razorback Mountain area the basal 50 metres alent to theRazorhack group. Two possibilities may of the Razorback group is characterized by thin-bedded, account for the discrepancies in age. If the rocks along the grey to black argillaceous limestone separated by thinner, Osilinka River are Razorback equivalents then it suggests tan to brown-weatheringargillaceous dolomite layers. The that Ordovician strata at Razorback Mountain have been upper 25 metres of the group is typified by thinly bedded removed by a pre-Echo Lake group unconformity. Alter- grey anddark grey shaleand slate together with thin- natively the Ordovicianshaly rocks may be tongues or thin bedded,dark grey to blackargillaceous limestone.This lenses of argillaceoushorizons within theEcho Lake argillaceous limestone can be upto IO metres thick and is group and are notequivalent to the Razorback group. This toward the top of the unit. latter interpretation is more probable considering the lack of abundant carbonate horizonsin the Ordovician shalesin South of Henschel Creek, Razorback exposures are comparison to theRazorback section on Razorback Moun- typifiedby grey to grey-green, brownish weathering tain.Further detailed work is needed to resolve this strongly folded shales and calcareous shales. Thin to moderately bedded, strongly laminar, brown-weathering, dark problem. grey argillaceous limestone is interlayered with thin dol- The Razorback Mountain succession represents the omitic layers toward the topof the unit (Plate l l). Similar first documented occurrence of Middle Cambrian strata lithologies were mapped near Mount Kison. west of the northern Rocky Mountain Trench (Fritz et a/., 1991).If Razorback rocks are restricted to the Middle Cambrian then there are no correlatives to thisunit within ECHOLAKEGROUP the northern part of the Cassiar Terrane. If the Razorback (Informal, Ordovician? to Lower Devonian) group is partly Ordovician in age then it would be equiv- The Echo Lake group takes its name from the spec- alent to parts of the Kechika and possibly the Road River groups in the Cassiar Mountains (Gabrielse, 1963; Nelson tacular cliffs it forms north of Echo Lake. It is the thickest carbonate sequencein the map area and can betraced from andBradford, 1987, 1993; Nelson et al., 1988). This correlation is also based on the stratigraphic position of south of Blue Lake, northwestwards tothe Osilinka River. Razorback rocks above the Lower Cambrian Atan Group It is upwardsof loo0 metresthick (Plate 12)and is and below the Ordovician to Devonian Echo Lake group,a composed of two units; a lower limestone and dolomite probable equivalent of the Sandpile Group exposed to the sequence approximately 600 to700 metres thick, followed north (see Echo Lake group). Razorback strata bear more by 100 to 200 metres of dolomite,sandy dolomite and similarities with the Kechika Group than with rocks of the quartzite referred to as the sandy dolomite unit. Road River Group. Fritz et a/. (1991) noted the lack of This carbonate sequence was originally mapped as Middle Cambrian strata within the northern Cassiar Ter- Sandpile Group by Ferri and Melville (1990a, b) based on rane and suggested thatit may be present as a condensed its similarities with theSandpile Group in the Cassiar sequence within Kechika Group strata; a possibility that Mountains (Gabrielse, 1963; Nelson et a/., 1988; Nelson now seems quite likely. and Bradford, 1987).

24 group. This suggeststhat the base of the Echo Lake carbonates may be as old as Middle Ordovician. Alternatively, if these shaly horizons are part of the Echo Lake group (as with the Lower Silurian graptolitic horizon) then the Echo Lake group is as old as the Early Ordovician, or possibly older. This thickcarbonate package, with its upper quartzites and quartzose dolomites, is very similar in age and lithology to the Sandpile Group of the Cassiar area (Gabrielse, 1963), but lacks the thick succession of fossiliferous reefal limestone which is typical of the Sandpile Group.This difference may be dueto thedepositional position of the Echo Lake carbonate with respect to the ancient carbonate platform. Plate I I. Thinly hedded and interlayered dolomitic and The Echo Lake group is believed to represent part of algillaceous limestone of the Razorhack group east of Henschel the lower Paleozoic platformal or slope carbonate facies. Creek. These rocks grade upwards into limestones of the Echo Lake group. A carbonate-to-shale facies transition occurs in the lower Paleozoicalong the entire length of theCanadian Cor- dillera (Wheeler and McFeely, 1991, Figure 4). North of the map area, shales, argillites and argillaceous limestones A.ge and Correlation of the basinal Ordovician to Silurian Road River Group Graptolites from shales at the base of this carbonate are equivalent to thick carbonates farther east, across the indicate an EarlySilurian lower age limit. Conodonts transitionboundary (Cecile andNorford, 1979). In the rlxovered from the top of this unit in the Otter Lakes area, Cassiar area, Nelson cf al. (1988) state that east of the indicate an upper age limit of Early Devonian (Appendix Kechika fault the Road River Group is restricted to the I). The preceding discussion on the Razorback group indi- Ordovician and appears much thinner. In this area (east of cated that Lower, and possibly Middle, Ordovician shaly the Kechika fault), Upper Ordovician to Lower Devonian horizons along Wasi Creek and Osilinka River (Fem et a/.. platformal carbonates are part of the Sandpile Group. West 1992a, b; 1993a. b) may be equivalent to the Razorback of theKechika fault, thick RoadRiver shales span the

Plate 12. Looking north at Razorback Mountain which is composed entirely of the Echo Lake group.

25 Ordovician to Silurian and the Sandpile Group is represented by the thinner Tapioca sandstone which is restricted to the Lower Devonian. The Echo Lake group is Ordovician? to Early Devo- nian in age. This coupled with its extreme thickness and the relative thinness of the Razorback group indicates that it is part of a long-lived platformal carbonate sequence. The Sandpile Groupin the Cassiar Mountains is extremely fossiliferousand believed to represent a reefalfacies. Reefoid deposits are not observed in the Echo Lake group indicating off-reef, but not basinal facies. On the east side of the McLeod Lake fault Stmik (1989a. 1990)describes a sequence of carbonatesand sandydolomites whichpossibly span the Ordovicianto Lower Devonian. The Ordovician Sandpile Group of the McLeod Lake area with its fossiliferous carbonate beds and quartzose layers, appears very similar to parts of the Sandpile Group of the Cassiar Mountains but has no correlatives in the study area. It is overlain by Lower Silurian limestone, dolostone and minor slate followed, in turn, by dolomite,sandy dolomite and quartzite thought to be LowerDevonian, based on similarities to the Tapioca sandstone in the northern Cassiar Terrane (Struik, 1989a). The Lower Silurian toDevonian sequence has similarities to the Echo Lake group in the map area. Rocks of the Echo Lake groupbear little resemblance to similarly aged lithologies of the Black Stuart Group in theCariboo-Barkerville area (Struik,1988a). Theyare thinner and composed primarily of slate with lesser chert and carbonate. Exceptions tothis are the minor sandy carbonate, carbonate breccia and cherty dolomite of the chert-carbonateunit which bears similarities with the sandy dolomite unit.

Lower Member Plate 13. Selective quartz replacement of carbonate of the Echo Lakegroup, near RazorbackMountain. These features appear The lower memberof the Echo Lake group is charac- organic in some localities and may represent algal structures. terized by sequences of light to medium grey, massively bedded limestone up to 2 metres thick. Sections of this carbonate member may be dolomitic as seen on Razorback Mountain where the lower few hundredmetres of this unit of metres thick. At one locality the shales contain mono- is dolomite.Sections of bioclastic limestone several graptolites of Silurian age, perhaps from the Llandoverian metres thick are found south of Echo Lake. The natureof stage. the clasts is indeterminate, though some appear tobe algal in origin. Semicontinuous quartz lenses and “vugs” (replaced Sandy Dolomite Unit algal structures(?), 1 to 2 centimetres thick, occur within The sandy dolomite unit is some 100 to 200 metres this member and sometimes form an interwoven network thick and is characterizedby moderately to thickly bedded comprising up to 20% of the rock (Plate 13). These are dolomite, sandy dolomite and quartzite. The dolomite is well exposed on the ridge leading south from Razorback usually massive though thin sections of algal laminae are Mountain. Thin beds or lenses of grey chert and isolated occasionally present. The sandy dolomite is light grey to bodies of polymict carbonate breccia up to 5 metres thick grey in colour, massive and comprised of up to30% well- arealso present along thesehorizons. Thickly bedded roundedmedium-grained quartz grains. Grey to black limestone of the lower member is interlayered with thinly quartzite layers, 1 to 2 metresthick, are presentin the bedded limestone and dolomite which commonly exhibits uppermost part of thisunit. The quartzite is very pure, algal laminae and layers of silicified oolites and pisolites having greater than 95% well-rounded quartz grains with up to 2 centimetres in diameter (Plates 14, 15). theremainder being carbonate cement. The quartzite is In the northern part of the map area the lower carbo- volumetrically a minor part of the unit (less than 5%) but nate member of the Echo Lake group contains sections of animportant feature, nevertheless. Dark grey to grey grey to grey-brown shale and argillaceous limestone tens argillite and siltstone are alsopresent, but rare in thisunit.

26 Plate 15. Silicified pisolites in the Echo Lake group near Racor- back Mountain. This lithology is only locally developed and is very distincr within the rather monotonous carbonate of the Echo Lake group.

these rocks are no younger than Middle Devonian. Their location above Lower Devoniancarbonates (Echo Lake group) andtheir similarities with the McDameGroup indicate that they are probablyrestricted to the Middle Devonian. Plate 14. Variably dolomitized algal laminae in Echo Lake group. Direct correlatives of the Otter Lakes group within near Razorback Mountain. This dolomitization is lypical of the the Cassiar Terrane are carbonates of the McDame Group lower pan of the Echo Lake group. of the Cassiar area (Table 2). Nelson and Bradford (1987, 1993) describefossiliferous, dark grey fetid dolostones andlimestones that hostseveral showings of lead-zinc- OTTER LAKES GROUP silver-harite mineralization. (Informal, Middle Devonian) In the McLeod Lake area, Struik (1990) notes grey The Otter Lakes group forms the oftop the Paleozoic and dark grey finely crystalline limestoneof Middle Devo- carbonate succession in thisarea. Monger and Paterson nian age. In the Cariboo-Barkerville area only minor Mid- (1974) noted that its faunal assemblages are no younger dle Devonian carbonate occurs within rocks of the Black than Middle Devonianand thus not part of the Cache Stuart Group (Struik, 1988a). Creek Group astheorized by Armstrong (1949) and Roots (19'54). This dark grey, fetid. fossiliferous dolomite, with Lifhology its abundant occurrences of replacement lead-zinc-barite The Otter Lakes group is some 150 to 200 metres mineralization, is very similar to McDame Group strata thick and is characterized by grey to black fetid limestone describedfarther north (Gabrielse, 1963; Nelson and and dolomite. Exposures tend to be poor and, away from Bradford, 1987, 1993; Nelson PI al., 1988). This led Ferri known mineral occurrences,the map trace is tentative. and Melville (1990a,b) to refer to theserocks as the These strata are only present in the northern pari of the MtDameGroup. They arenow named aftertwo small map area, where they form a semicontinuous trace from lakes centredwithin an area containing extensivelead-zinc south of Blue Lake, northwestward to the Osilinka River. mineralization (Figure 7). Exposures are good around Otter Lakes and along Flegel Creek. Age Correlation and Two members of the Otter Lakes group are recog- The presence of twin-holedcrinoid columnals, nized. This distinctioncannot always be madeand in together with conodont data (Appendix I), indicates that places lower Otter Lake group limestones crop out imme-

27 diately below the Big Creek group. The lower pan of the upper part of the Big Creek group marks the top of North group is characterized by thin to thick-bedded, dark grey American stratigraphy in the area. to black, fetidlimestone. Thelimestone, although not Argillites andcarbonates of theupper Big Creek abundantly fossiliferous,contains rugosan corals, group were not recognized in the far northwestern part of brachiopods, gastropods, bryozoa(?), amphipora and beds the map area (west of Mount Howell). Their absence in of crinoidossicles, some of which exhibittwin-holed this area may be due to non-deposition or, more likely, to columnals. Parts of the unit are coarsely recrystallized and faulting as shown in the cross-sections (Figure 8). contain vugs filled with calcite andpyrobitumen. The Highly tectonized argillites and calcareous argillites upper part of the group is characterized by a slightly fetid alongthe Manson fault zone and southwest of Munro grey to tan, finely crystalline dolomite and minor lime- Creek are tentatively assigned to the Big Creek group, but stone which may show faint bedding. they may represent fault slices of argillites belonging to the Triassic Slate Creek succession. The strongly sheared BIG CREEK GROUP nature of lithologies makes their assignment equivocal. (Informal, Upper(?) Devonian to Lower Permian) Shales, argillites, minor sandstones and tuffs (Gilli- Age and Correlation land tuff) of the Big Creek group were originally placed Microfossil collections have been recovered from an within the argillaceous member of the Cache Creek Group interlayered limestone and siliceous limestone unit in the by Armstrong (1949) and Roots (1954). Gabrielse (1975) uppermostpart of theBig Creek group (Appendix I). notedtheir similarity to UpperDevonian strata in the These conodonts and fusulinidsindicate an Early Permian Cassiar Mountains but, due to poor fossil control, placed upper age limit. Conodontsrecovered from the middle part them with a group of rocks now equivalent to the Nina of the unit in the Otter Lakes area yielded an early Mis- Creekgroup. Ferri and Melville (1990a. b) called the sissippian age (Appendix I). The stratigraphic position of lower part of this succession the Earn Group due to its the Big Creek group above the Otter Lakes group, and its similarities to strata in the Cassiar Mountains (Gabrielse, similarity to the Earn Group farther north, suggest a lower 1963; Nelson and Bradford, 1987). Ferri el a!., (1993a. b) age limit of LateDevonian, Dark grey to grey wavy referred to the upper part of the Big Creek group as the argillites with minor limestone and rare tuff in the upper Cooper Ridge group afteran earlier version of the present part of the unit sit stratigraphically above the early Mis- work. It is now felt that there is not enough distinction sissippianfossil locality. Underlying rocks are typically between rocks of the Big Creek and Cooper Creekgroups blue-grey planar bedded argillites and shales with minor to classifythem separately and the termCooper Ridge sandstones, wackes and felsic tuff. groupbas been discarded. The Big Creekgroup now Preliminary U-Pb geochronometry hasbeen obtained encompasses all rocks between the Otter Lakes and Nina from zircon concentrates from the Gilliland tuff (Appen- Creek groups. dix 11). The best estimatefor the age of this tuff is These rocks are well exposed near the headwaters of 377.3212 Ma taken from the intercept of the three-point Big Creek. The unit also sporadically crops out south of regressionline (Figure 68). Theupper intercept on the the Otter Lakes in a series of small fault blocks, along the concordia plotis at approximately 2.43 Ga, clearly indicat- banks of the upper parts of Flegel Creek and along Cooper ing the presence of Precambrianinheritance. These zir- Ridge.The upper part of thissequence forms good cons have experienced leadloss suggesting that the age of exposures north and east of Mount Howell. the tuff may be older (Appendix 11). The upper part of the Big Creek group was originally The lower part of the Big Creekgroup is broadly placed within the Slide Mountain Group (unit PPsml) of correlative to the blue-grey, fissile shales of the Devono- Ferri and Melville (1990a. b), but is now believed to be Mississippian Earn Group in the Cassiar area. The Earn part ofCassiar Terranestratigraphy. This is based on Group is also characterized by minor amounts of chert, several factors: conodonts recovered from the top of the quartz wackes and sandstones (black clastics) which are unit indicate a continuous stratigraphic sequence between also a small component of the Big Creek group. The Earn it and strata now interpreted as the lower part of the Big Group is also noted foroccurrences of stratiformlead- Creek group; the conodont species (Appendix I) are more zinc-barite mineralization. The presence of stratiform bar- indicative ofa shallow marine environment rather than the ite in shales and argillites in the Munro Creek area sug- oceanfloor setting of theNina Creek group (M. J. gests that they are part of the Big Creek group. Orchard, personalcommunication, 1990; Struik,1988a); Correlative of the Big Creek group in the Cariboo- argillites and shales of this unit apparently grade confor- Barkerville area is the Upper Devonian and Lower Mis- mablyinto those of the lower Big Creekgroup and sissippian Guyet Formation (Struik, 1988a) which is pre- lithologicallythis unit has moresimilarities to the Big dominantly a clastic sequence composedof conglomerate, Creek argillites,shales and minor clastics than to the sandstone and greywacke. These lithologies form a minor chertysediments and igneousrocks of the NinaCreek part of the Big Creek group. group. Struik (1990) describes darkgrey to black slate, The overlying Pennsylvanian to Permian Nina Creek argillite and minor limestone of Carboniferous (Tournai- group must rest structurally above the Big Creek group. sian) age, east of the McLeod Lake fault. The characteris- Rocks of theNina Creek group are part of the tics of this package are very similar to those of the Big allochthonousSlide Mountain Terrane. Therefore the Creek group.

28 Devono-Mississippian felsictuff is observed elsewhere in rocks of North Americanaffinity in the Cordillera. Schiarizza and Preto (1987) describe bodies of Middle Devonian to upper Mississippian rhyolitic material within theEagle Bay andFennel1 successions in the Adams Plateauarea. Eagle Bay rocks are pan of North American stratigraphy and some are time correlatives to rocks of the Big Creek group. Mafic volcanic rocks of possibly similar age are also found in theBlack Stuart Group (Struik, 1988a). Agglomerate, tuff and pillow basalt make up the hulk of th,e Waverly Formation which Struik tentatively correlates with the Earn Group. a direct correlative of the Big Creek g1-0up. Felsicvolcanics are not recognized in the Devono- Nlississippian Earn Group of the Cassiar area but are well documented in the EarnGroup of theSelwyn Basin (Gordey er al., 1991).They includetuff, breccia,flow rocks and their small intrusive equivalents. The Mississippian to Permianupper section of the Big Creek group is in pan correlative with Mississippian to Permian sediments in the northern part of the Cassiar Terrane(Nelson and Bradford, 1993). Thesediments in the Midway area are characterized by varicoloured ribbon chert which is not found in the Big Creek group. Similar age sequences south of the map area are slates and carbonates of the Allex Allan Formation and succeeding Penn- sylvanian carbonates of an unnamed unit (Struik, 1988a). Struik (1989a. 1990) describes tuff and cherty tuff of Permianage in the McLeod Lakearea. They sit above ar;$illite,slate and limestone which are in partCar- Plate 16. Grey, extremely fissile.shales of the Big Creek group, northwest of Echo Lake. This shale typically breaks into large, boniferous. This tuff and argillite has an overall similarity thin, flexible sheets which is Characteristic of this unit. to rocks of the upper Big Creek group, though tuff in the latter is subordinate. Permian sediments are uncommon in the Cassiar and thick,and have a characteristicblue-grey colour Kootenay terranes, but Struik (1988a) described Permian (Plate16). Up-sectionthese shales becomeinterlayered crinoidallimestone (Sugar limestone) inthe Barkerville with thickerbedded argillites and silty argillites. This arm which is part of the Barkerville (Kootenay) Terrane. sequence is approximately 400 to 500 metres thick. Southwestof Mount Brown, approximately 30 Lithology metres of thicklybedded quartz-chert sandstones are A sequence of shales and argillites is exposed near found in the upper part of this sequence. These sandstones the headwaters of Big Creek and is assigned to the Big contain thin, discontinuous layers of dark grey to black Creek group. This unit is 600 to 800 metres in thickness argillite, very similar to lowerBig Creek group. The sand- andcharacterized by blue-greyor dark grey shales, stone is predominantly quanz (greater than 90%) with the argillites,limestone, felsic tuff and sandstones. Typical remainder being chen (Plate 17). The grains are rounded Big Creek shales are confined to the northern pans of the and medium to coarse grained. map area, betweenBlue Lake andthe Osilinka River. Limestone, though rare, is exposed in the upper pans Occurrences of similarshales are foundin the south, of this succession. It is dark grey to black, argillaceous and primarily along the Manson fault zone and south of Munro only a few metres thick. Near Munro Creek the argillites Creek. In theseareas the unit is muchthicker, due to and slates can be calcareous and approach an argillaceous faulting,and is probablytectonically interleaved with limestone in composition. Abuff-weatbering, white to rocks of the Slate Creek succession. beige,recrystallized limestone is exposednear Munro The Big Creek grouphas been locally subdivided into Creek. It is upwards of 5 metres thick and contains thin to twopans basedprimarily on thecharacter of bedding moderately thick beds of calcareous siltstone or phyllite. within the argillites. Shales and argillites in the lower pan Its stratigraphic position is uncertain due topoor exposure of the Big Creekdisplay highly planar bedding, in contrast and tectonic disruption near the Wolverine fault zone.This tothe wavy bedding in theshales and argillites of the limestone may be pan of theupper section of theBig upper part. Creek group. Lower Part: The lower shales are extremely fissile, Bariteoccurs in theslates and argillites of this forming large,thin, flexiblesheets severalmillimetres sequence inthe southeastern quarter of themap area.

29 Upper Part: This unit can he easily confused with shales and argillites of the lower Big Creek group. Gener- ally, the older shales are highly planar which is atypical of shales and argillites in the upper section. The upperpart of the Big Creek groupis some 200 to 300 metres thick in the northwestern comer of the map area. Elsewhere it may be tectonicallyinterleaved with other argillite packages and its thickness is unknown. It is composed predominantly of grey to dark grey or black, rustyweathering, thin-bedded, wavy to platyargillites (Plate 18). Of lesser importanceare argillaceouslimestone, quartz wacke and felsic tuff. Argillitemay grade into slates or phyllites with cleavage becoming the dominant planar fabric. These slates and phyllites predominate in the southern half of the map area. The upper part of this succession contains 5 to 10- metresections of thickly bedded, interlayered huff- Plate17. Photomicrograph of quartz-chert sandstone to wackr weathering limestone and silicified limestone (Plate 19). (“black clastic”) in the upper pan of the Big Creek group along The siliceous limestonetypically appears cherty andis the the south side of Flegel Creek. This sandstone sequence is up to only cherty material within this sequence. tens of metres thick. Lenses of dark grey to black, massive to poorly bedded chert-quartz wacke, IO to 20 metres thick,are Moderatelybedded barite is exposedalong a creek between Gaffney and Munro creeks (McCammon, 1975) in sections up to 7 metresthick (see also Table 6 and chapter on Economic Geology). Gilliland Tuff Light coloured felsic tuff outcrops at several localities within the lower Big Creek group. Tuffs form boththin, discontinuous layers lessthan a metre thick and large bodies up to several square kilometres in area. A poorly exposed, northwest-trending body of dacitic tuff crops out on the north shore of the Ornineca River, oppositeGermansen Landingand is referred to as the Gilliland tuff. The best exposures are justbelow the bridge and on the north sideof the road leading into the Gilliland Lodge. Approximately 5 kilometres southeast along strike, is another body of tuff. Its outline is tentative as it is based on only four outcrops. This unit is surrounded by argillites of the Big Creek group and contactrelationships are not seen. The rocks are grey to cream on freshsurface and grey to brown weathering. They are composed of up to 30% quartz clasts, 5 to 10% plagioclase and potassic feldspar crystal fragments, I to 2% muscovite and biotite and minor hornblende and zircon. The groundmassis recrystallized to sericite, carbonate, quartz and chlorite. The best-preserved quartz clasts exhibit resorption embaymentsand the mica is commonly bent. The tuffs display a penetrative foliation.

Similar tuff beds are foundin the hydraulic pits along the Germansen River approximately 2 kilometres southwest of Germansen Landing. At this locality tuff beds, 20 centimetresto more than 2 metresthick, are in sharp contactor grade into the phyllitesand argillites. They occasionally containrip-up clasts of argillite and fill scour channels in the sediments. Theyare white tocream in ColOUr, tan to rusty weathering and contain up to 80% coarsequartz andfeldspar crystal fragmentswhich are Plate 18. Massive to weakly fissile argillites and shales of the sometimes graded. upper pat? of the Big Creek group northwest of Mount Howell.

30 Plate 20. Photomicrograph of quartz-chen wacke (black clastic) from nonheest of Cooper Ridge. These clastic rocks are a very minor component in the upper pan of the Big Creek group and commonly contain a nonhwest-trending lineation produced by stretched clasts.

show resorbedmargins. These rocksare similar to the Gilliland tuff but may be younger. Alternatively, they may be a fault repetition of Gilliland tuff from the lower pan of the Big Creek group.

BLUE LAKE VOLCANICS (Informal, Eocene?) Massive, dark grey, olivine-bearing basalts and vol- canicbreccia crop out near BlueLake (A. D. Halleran, personal communication, 1989). Only a few scattered outcrops of basalt were observed during mapping and, based on aeromagneticdata. we believe that these basalts are restricted to within I kilometre of Blue Lake. These rocks lack the penetrative fabric seen in surrounding Paleozoic and Proterozoic sediments. Severalundeformed, mafic dikes cutrocks of the lower Swannell Formation near Munro Creek and in the loweringenika Group northwest of theManson River. These intrusions have been included with the Blue Lake volcanics.

Age and Correlation

Plale 19. Interlayeredlimestone and silicified limestoneimme- Extensivepost-Jurassic mafic volcanics in the Fon dialely helow (structurally) Nina Creek sediments northcast of St.James area were assigned to the EndakoGroup by CooperRidge. This sequence of carhnnates yieldedPermian Armstrong (1949). Hesuggested they areOligocene or conodontssuggesting a continuousstratigraphic sequence with younger based on stratigraphic relationships. More recent underlying rock< of the Big Creek group. work indicates that Endako Group volcanism is of Eocene age (Mathews, 1989; Souther, 1991). sporadically exposed in the lower parts of this sequence. The clasts are fine to coarse grained, subangular to sub- INTERMONTANE SUPERTERRANE rounded, predominantly chert, and make up less than 50% In the map area the IntermontaneSuperterrane is of the rock (Plate 20). These rocks are well exposed near represented by the Quesnel and Slide Mountain terranes Cc'oper Ridge. and the Harper Ranch Subterrane. Arc-related sediments In the far northwestern corner of the study area sev- and volcanics of the Quesnel Terrane belongto the Middle eral metres of light grey to cream-coloured quartz-bearing Triassic toLower Jurassic(?) Takla Group.The Harper felsic tuff are present within thesuccession. The tuff Ranchsubterrane is asubdivision of Quesnelliaand is containsupwards of 20% medium-grainedsubhedral representedby the upper Paleozoic Lay Range qu,artz crystals andcrystal fragments which commonly assemblage, a sedimentaryand volcanic arc sequence.

31 HarperRanch rocks in southern British Columbia are thrust fault separates the two along their eastern contact. unconformablebelow Mesozoic strata of Quesnellia Reconciliation of dataleads us toassume thatbasalts (Monger et a[., 1991). The upper Paleozoic Slide Moun- which were fed by, and were immediately above the gab- tain Terrane comprises the Manson Lakes ultramafics, and broic bodies were thrust eastward and replaced by older oceanic volcanics, sediments and mafic igneous rocks of andor more westerly derived basaltic successions.Basalts the Nina Creek group. above the fault slivers of Mount Howell sediments northwest of Nina Lake are assumed torest conformably above SLIDE MOUNTAIN TERRANE these sediments as fossil data are lacking within basalts stratigraphically above this contact. NINA CREEK GROUP The similarity of Nina Creeksediments with Mis- (Informal, Mississippian to Permian) sissippian to Permian rocks of the Cassiar Terrane sug- In the Manson Creek and Germansen Landing areas gests a geneticrelationship between them. However, rocks of theNina Creek group werefirst describedby feeders for the basalts of the Pillow Ridge succession are Armstrong(1949) who placedthem within the Manson lacking in NorthAmerican rocks, indicating that the Lakes belt of the Cache Creek Group, on thebasis of the basaltswere formed ina setting different than Cassiar lithologicsimilarities betweenthe twoassemblages. He rocks. Data obtained by ourselves and others (Gabrielse, used the term “Nina Creek greenstones” to describe the 1975).indicate that the Nina Creek group represents thick sequence of volcanics in the upper part of the Nina ocean-floor material. This, in conjunction with data from Creek group. Monger (1973), Monger andPaterson (1974) elsewhere along the belt, suggests that these rocks were and Gabrielse (1975) realized the distinct nature of these formed in a basin near the western margin of North Amer- rocks, although they did not formally name them. Monger ica andwere thrust onto North American rocks during (1977a) described themost completesequence of this later compressional tectonism. package in the Nina Creek area and comparedit with other Paleozoic volcanic assemblages along the belt. Ferri and Melville (1988, 1989, 1990a) termed these rocks the Slide Age and Correlntion MountainGroup based on theirapparent similarities to Fossil collections by the authors (see Appendix 1) and rocksdescribed in theBarkerville-Carihoo area to the others (Monger, 1977a; Gabrielse, 1975) indicate that the south (Struik, 1988a). Nina Creekgroup spans the Mississippian to Permian Theyare now termed the Nina Creek group in periods. Fossil data also showthat each succession within accordancewith early workers (Armstrong, 1949; theNina Creek group is roughly time equivalent Monger, 1977a) whomade reference toNina Creek in (Figure 14). Thus, a major thrust fault must separate the describing the package.It is feltthat a local name will two major packages within the group. This implies that betterdifferentiate them from similar rocks elsewhere volcanic rocks of the Pillow Ridge succession have been along the belt. thrust eastward onto sediments of the Mount Howell suc- In the northern part of the map area these rocks are cessionwhich, in turn, have been placed on top of beautifully exposed around the headwaters of Nina Creek. argillites of the BigCreek group. If thisthrust stack Here, a thickness of nearly 7 kilometres of basalt, argillite, follows normal relationships (Boyer and Elliot, 1982) this gabbro, chert, siltstone, and minor sandstone make up the implies thatthe basalts of the Pillow Ridge succession Pennsylvanian to Permian Nina Creek group. It has been represent more distal parts of the Nina Creek basin and subdividedinto two informal units, the lower Mount that the Mount Howell succession was deposited closer to Howellsuccession, which is composed of siliceous theNorth American craton.This is explained in more argillite, chert, gabbro and siltstone and the upper Pillow detail below. Ridge succession which is predominantly basalt. At Nina The Nina Creek group is part of the Slide Mountain Creekthese units form an apparently continuous Terrane, a semicontinuous belt of oceanic rocksthat can be southwest-dipping stratigraphic package,whereas to the traced along the entire length of the Canadian Cordillera south, the group has been dissected by the Manson fault (Figures 15 and 16). Rocks of the Slide Mountain Terrane zone and this apparent stratigraphic continuity is lost. have been described as an ophiolitic sequence (Monger, Basalsedimentary rocks of the NinaCreek group 1984) though all the elements of a classic ophiolite arenot appear to rest conformably on sediments of the Big Creek always present. Parts of the Nina Creek group are very group. Fossil data show that a major thrust fault separates similar to rocksseen within nearby correlatives suchas the these rocks from rocks of the Cassiar Terrane. These data Sylvester allochthon to the north and the Slide Mountain also indicate the presence of a significant thrust between Group to the south, (Figure 15). These similarities include both successions of the Nina Creekgroup. The thrust the thick volcanic sequence, cherty sedimentary package faultsdelineated thus far also suggest that the internal and argillite sequence. geometry of each successionof the Nina Creek groupmay Correlations of Paleozoic oceanic rocks alongthe he an imbricate thrust stack. entire belt have been made in the past (Monger,1977a) The compositional similarity of gabbroic sills in the and have shown the similarities of thevarious units. A upper part ofthe Mount Howell succession with basalts of brief account of the various units within the Slide Moun- the Pillow Ridge succession suggests they are feeders to tain Terrane of the Canadian Cordillera is givenbelow, to the basalts.Yet fossil data fromboth successions indicatea show how they correlate with the Nina Creek group.

32 aArgilliie =Gabbro Pillowed badis tSllistone Chert ~~~$eg~~~$Ullmmafiia (wehrlil,) a8ressia

Figure 14. Schematic siratigrdphic columns of Nina Creek Group withln the map area.

Rocks of theSylvester allochthon represent highly dismembered ophiolitic and island arc suites. Workers in thisregion (Nelson andBradford, 1987, 1993; Nelson cf a/., 1988;Harms. 1984, 1985a. b, 1986)have suh- divided this package into three divisions, all of which span theearly Mississippian to Permiantime period. Units within each division are in thrust contact with each other as indicated by older-over-youngerconodont ages. This furtheremphasizes thehighly imbricated nature of the allochthon. Divisions I and I1 represent rocks of Oceanic (ophiolite) affinities whereas rocks of Division 111 have an island arc signature. Division I consistspredominantly of argillite,siliceousargillite, varicoloured chert, limestone, siltstone, sandstone and minor diabase sills and basalt. Cherty sediments and basalt form the younger or upper part of the sequence.These rocks are probablecorrelatives of the Mount Howell succession, though Division I contains sediments as old as early Mississippian. The oldest sediments yet recorded in theMount Howell succession are early Pennsylvanian. The structurally higher Division I1 is composed pre- dominantlyof basalt-diabase-sediment sequences and slivers of ultramafic rocks. This package has an overall similarity with rocks of the Pillow Ridge succession. In the Nisutlin Plateau of the Yukon Territory, rocks of theSlide Mountain Terrane are represented by the Boswell and Semenof formations (Monger et al., 1991). Thelower to middlePennsylvanian Boswell Formation appearscorrelative with the Mount Howellsuccession. Figure 15. Distribution of the Slide Mountain assemblage This is based on thepredominance of slateat its base throughout the Canadian Cordillera. which is followed by chert, greywacke,grit, greenstone

33 """"""""""""" """"""""""""" """""" """"""""""""" """"""""""""" """""Y"""""""

Figure 16. Stratigraphic correlation chart of the Nina Creek group and other formations of the Slide Mountain Terrane of the Cordillera (modified from Monger, 1977). along the length sills and capping pillowed volcanics. The upper Pennsyl- In the Adams Lake area, Schiarizza and Preto (1987) vanianSemenof Formation withits massivebasalt is describe rocks belonging to the Mississippian to Permian directly correlative with thelower partsof the Pillow Fennel1 Formation. In this region, the structurally lower Ridge succession. divisionconsists of chert,diabase, gabbro, sandstone, In the eastern part of the Yukon Territory, strongly quartz feldspar porphyry and lesser basalt. These rocks are dismembered rocks of the Anvil allochthon (Tempelman- succeeded by the structurally higher division composed Kluit, 1979) are most likely correlative with rocks of the almostentirely of Permianand possibly Pennsylvanian NinaCreek group. In this region argillaceous and basalt. These units are correlative with the Mount Howell tuffaceouscherts of theAnvil RangeGroup (Gordey, and Pillow Ridge successions, respectively. 1983) are Early Permianin the upper part and are followed Farther south, basalts, cherts and ultramafites of the by massive to pillowed hasalts. These may be equivalent Pennsylvanian(?) to Petmian Kaslo Group correlate with tothe Mount Howell and Pillow Ridge successions, similarlithologies of the Pillow Ridge succession. The respectively. Mississippianto lower Pennsylvanian Milford Group, To the south, in the Cariboo-Barkerville area (Struik, with itssiliceous sediments, limestones andvolcanics, 1988a,Campbell ef ul., 1973, Sutherland Brown, 1963) appears grossly similar to the Mount Howell succession. and in the Prince George area(Tipper, 196 I ; Struik, 1985), This package unconfotmably overlies sedimentary rocks the SlideMountain Terrane is represented by the Slide of North American affinity (Klepacki and Wheeler, 1985). Mountain Group. This package is predominantly basalt, chert, cherty argillite and diabase. with lesser agglomerate, greywacke, black slate and ultramafite. Struik (1988a) and Mount Howell Succession Struik and Orchard (1985) describe conodont suites from (Informal, Mississippian To Permian) the Slide Mountain Group which span the early Mississip- This succession is named after Mount Howell where pian to Permian periods. Sutherland Brown (1963) reports it is well exposed along a broad, northwest-trending syn- that cherts and argillites are more abundant in the lower cline. In the type areathe succession is upwards of 1 part of the Slide Mountain Group. This sequenceof rocks kilometre thickand in thecentral paltof the study area it is is very similar in age andlithology to the NinaCreek estimated to be some 2.5 kilometres thick. In the southern group. part of the study area structural complexitiesand poor

34 exposures do not allow even an approximate estimate of kilometre in thickness and are carried on a thrust which thickness. disappears northwestwardwithin monotonous basalts of This unit is well exposedalong a series of ridges thePillow Ridge succession. Thesesediments andgab- emanating from Cooper Ridge. Exposures are reasonably broicrocks were originallythought to be intravolcanic good around Echo Lakeand Blue Grouse Mountain. South sedimentary sequences by Ferri and Melville (1989). Fos- of .the Omineca River, the succession is confined to the si1 data now indicate an age inversion at the base of the subalpine elevations and only small outcrops are exposed. section east of Nina Creek. This, in conjunction with In thesouthern part of the maparea relatively good tectonically disrupted rocks at the base of one package, exposures are found southwest of Ciarelli Creek. indicates they are fault repetitions of the Mount Howell Lithology: In the Mount Howell area dark argillites succession. of I~heBig Creek group are succeeded by thin to moder- Gabbroic sills up to IO00 metresthick intrude the ately bedded grey argillites, light greyto greenish siliceous upper parts of the Mount Howell succession. Thesebodies argillites, light grey, green and maroon cherts and ribbon are found at various stratigraphic levels and are traceable cherts of the Mount Howell succession. These rocks are for several kilometres in some places. They are beautifully intruded by gabbroic sills and dikesin the upper part of the exposed along the ridges descending off Mount Howell succession. The maroon and salmon-coloured cherts only (Plate 22). They arefine to coarsely crystalline, with occur in the uppermost part of the section, either in associ- subequal pyroxene and strongly altered (sericitized) plag- ation with the gabbro or immediately below the basalts. ioclase. The compositionalsimilarity of thesesills with Cherts are massive tothickly bedded. Ribbon chert is rare basalts of the Mount Howell and Pillow Ridge successions andl is composed of thin chert layers (I to 5 centimetres) (see underChemical Analysis and Tectonic Setting of separated by thinner, cleavedsiliceous argillite layers Nina Creek Basalts) suggest that they may be feeders to (Plate 21). Minor constituents arebuff-weathering micritic the basalts. limestone layers less than 0.5 metre thick, basaltic flows South of Nina Lake the composition of the Mount ancl aquartz-bearing tuff towardsthe base of theunit Howell succession is slightly different. Near Blue Grouse which is very similar to felsic tuff described in the Big Mountain the upper chertsand siliceous argillites are inter- Creek group. layered with basalt flows. Basalt flows are also exposed Discontinuous sections of the Mount Howell succes- near JackfishCreek and along theridge southwest of sin]?occur northwest of Nina Lake. Theyare up to a Ciarelli Creek.These massive flows can be up to 50

Plate 21. Rihboned cherts of the Mount Howell succession east of Gaffney Creek. Here I to kentimetre thick chert layers are separated by thinner cherty argillite beds.

35 Plate 22. Gabbro sills within the Mount Howell succession as seen looking south from near Mount Howell. In this photograph up to four levels of sills can be seen in the background. The thickest is at the base and may feed into the higher ones. metres thick and the upper parts contain tuffaceous brec- quartz grains) andrare, bmken crystals of potassicand cia. Some of the thicker flows can be mistaken for finely calcic feldspar. In the Gaffney Creek area the sandstones crystalline, mafic intrusions. The basalts appear very simi- are quartz rich with the quartz crystals displaying a blue lar to those of the Pillow Ridge succession (see following opalescence. section). Age: Nine conodont suites were recovered from the Southeast of theWolverine Lakes, the Mount Howell Mount Howell succession, of which only five gave con- succession contains minor sequences of tuffaceous sedi- clusive ages. These suites indicate this succession spans ments. These aremassive to thickly bedded, grey to green- Mississippianto Permian time (Appendix I). North of ish in colour and occur in sections up to 5 metres thick. Mount Howell, the lower part of the succession yielded Theserocks grade into typicalargillites of theMount Mississippian conodonts. Near Cooper Ridge, conodonts Howell succession. Coarser fractions contain crystal frag- collected from a lens of chert within a gabbroic sill indi- ments such as feldspar and pyroxene. The tuffaceous sedi- cate a Permian age forthe upper part of the succession.All ments appear to become volumetrically important in the localities are widely separated and the data do not rule out CiarelliCreek and Munro Creek areas where they are thepossibility that thrust repetitions occur within this interbedded with coarse quartzose sands. Some of these succession. tuffaceous sequences bear similarities to the Lay Range assemblage tuffs suggesting either they are part of the Lay Range assemblage or represent a possible link between it Pillow Ridge Succession (Informal, Early and the Nina Creek group. These tuffs are found within Pennsylvanian to Late Permian) sections typical of the Mount Howell succession preclud- The Pillow Ridge succession is at least 5 kilometres ing direct placement within the Lay Range assemblage. thick northwest of Nina Lake and is composed of massive Polymict sandstones, wackes and conglomerates are and pillow basalts and basaltic breccia, with lesser sedi- a rare component of the Mount Howell succession. They ments, tuff and sills of gabbro. The best outcrops are near are interlayered with argillites and tuffaceous sediments, PillowRidge. This exposure continues southeastward, in sections up to 10 metres thick. They can be seen on alongseveral ridges, toBlue Grouse Mountain where BlueGrouse Mountain, south of CiarelliCreek, near thick sectionsof basalt are preserved in a faulted syncline. Cooper Ridge and approximately 1 kilometre south of the Only small areas of basalt are preserved as thin remnants MansonRiver along the main roadthrough the area at the top of the Mount Howell succession in the southern (Gaffney Creek). These coarseclastic sediments arethin to part of the map area. Southwest of Ciarelli Creek, hasalts moderately bedded, composed of subrounded to rounded exposed at the top of the ridge have been included in the clasts of chert,quartz, carbonate, argillite(?), feldspar- Mount Howell succession although they may actually be pyroxene-porphyriticvolcanic, metamorphic rock frag- the base of the Pillow Ridge succession. Fault slices of ments (as shown by undulose and sutured polycrystalline basalt are also present within the Manson fault zone.

36 Plate 23. Pillowed basalts of the Pillow Ridge succession along Pillow Ridge.

Lithology: Over 95% of the Pillow Ridge succession give a Late Permian (Guadalupian) age. Individual cono- i!. composed of darkgreen to greyishgreen, variolitic, dontsuites recovered elsewhere in this succession are pillowed (Plate 23) or massive basalt whichcontains irreg- Permian. ular bodies of fine-grained gabbro. These gabbros may be The base of the Mount Howell section, northwest of the cores of very thickbasaltic tlowsas it wasoften NinaLake, is Pennsylvanianin age. Structurally below difficult todistinguish between mafic sills and thick basal- this point thin cherty sediments within the basaltic section tic flows. Massive and interpillow basaltic breccia is also contain conodonts which indicate a Pennsylvanian age and common. Very fine to fine-grainedphenocrysts of feld- another suite contains Permian conodonts. Basalts above spar, pyroxene and olivine are found locally in the basalts. this sedimentary package, and others along strike with it, The groundmass is composed of titan augite, plagioclase are assumed to be Late Permian. Alternatively. these upper and opaques of unknown composition. Alteration minerals basalts may be a thrust-sliver of the lower basaltic section. arechlorite, epidote, clinozoisite, prehnite and pum- The fossil data do notpermit resolution of these pellyite, all of which occuras individual grains in the hypotheses. groundmass or as vein and vesicle fillings. Sedimentary sections from 1 to IO metres thick occur within the basalts and are composed of light to dark grey Chemical Analysis and TectonicSetring of the Nina argillite and siliceous argillite, varicoloured cherts (cream, Creek Basalts grey. green, salmon and maroon) and gabbro sills. These Representativerock analyses were obtained for sedimentary rocks include lithologies very similar to those basalts and gabbros from the two successions of the Nina in the Mount Howell succession. Wavy argillites and rib- Creekgroup. In total, 16 basaltsand 18 gabbros were boned chert are thin to moderatelybedded. Cherts may analyzed. The results are presented in Appendices III and also be thick to massively bedded. In many localities the IV andthe location of samples used in the following cherts fbrnm large. shapelessmasses up to IO metres in diagrams are shown in Figure 17. These samples were the diameter within the basalt. least altered and as such would be the most representative. Age: Fossilscollected byourselves and others Most gabbro samples were taken from the Mount Howell (Monger. 1977a) indicate that the Pillow Ridge succession succession, only two samples are from the Pillow Ridge ranges in age from early Pennsylvanian to Late Permian succession. (Appendix I). Immediatelynorthwest of BlueGrouse All samplesare lower greenschist to prehnite- Mountain, near thebase of the succession,conodonts pumpellyite metamorphic grade (see chapter on Metamor- extracted from cherts yield an early to middle Pennsylvd- phism). As a consequence, major element mobility may nian age. Northwest of Nina Lake,conodonts froma have occurred during metamorphism and analytical results sedimentary sequence in the upper part of the succession should be viewed with caution. The basalts and gabbros

31 Nlna Creek Group

0 Basalt a Gobbro Takla. Group

0 5 10

38 vvv\/vvvvv 4~820 + K2O MO

Figure 18. AFM plot of Nina Creek basalts and gabbros (after Figure 20. Ternaryplot of Ti/100 - Zr - Srl2 for Nina Creek lrvine and Baragar. 1971). basalts and gabbros. OFB=ocean-floor hasalts: lAB=island-arc basal&; CAB=calcalkaline basalls (after Pearceand Cann, 1971).

20, II

I8 - A borolf gabbro I6 - - ..; I4 5 12 -

+ n

7b A do 85 - s10* (*I Z) IFigure 19. Plot of tntal alkali VPI.TU.Y silica for Nina Creek basalts and gabbros (after lrvine and Baragar, 1971). are tholeiitic in composition. based on an AFM ternary Figure 21. Ternary plot OS Til100 - Zr - Yx3 for Nina Creek plot (Figure 18). An alkali wt-sus silica plot (Figure 19) basalts and gabbros. A-ocean-floor hasalts; A, B=low- shows the subalkaline nature of the basalts. potassium tholeiites: B. C=calcalkaline basalts; D=within-plate basalls (after Pearce and Cann, 1973). Severaldiscrimination diagrams have been de,veloped for basalticrocks utilizing minor and trace elements, as they are relatively immobile during regional strontiumexhibits a slight spread of values dueto its mrtamorphim(Pearce and Cann, 1973; Pearce, 1975; mobilityduring metamorphism. Figure 22 also defines Floyd and Winchester, lY75). They are useful indicators of the chemical nature and original tectonic setting of these these tholeiitic basalts as being of ocean-floor origin. igneous rocks. Samples from the study area have been Extended trace element data for selected samples of plotted on some of these diagrams (Figures 20, 2 I, 22, 23 Nina Creek basalts and gabbros have an overall flat signa- an,i 24) and clearly indicate that these rocks are tholeiitic ture and have normalized values close to unity. which is ocean-floor basalts. Their tholeiitic nature is clearly shown typical of mid-ocean ridge basalts (MORB; Pearce, 1982: by the immobile elements which are independent of alkali Figure 25). Thelarge scatter within theelements strontium cvntent (Figures 23 and 24). The combination of Figures through to barium is due to mobility of these elements 20 and 21 illustratesthe relatively tight cluster of data during metamorphism. Average values for these elements within the fields designated as ocean-floor basalts. Only are in agreement with typical MORB signatures.

39 18000 These data are similar to analyses reported by Rees A boslrll (1987) on the Antler Formation from the Quesnel Lake qobbro area. He concluded that greenstones of the Antler Forma- 15000 tionalso represent ocean-floor basalts. Schiarizza and Preto (1987) present analyses for basalts of the Fennell Formation, a direct equivalent of the Nina Creek group. Using similar plots to those presented here, they too concluded that Fennell basalts are ocean-floor tholeiites. The chemistry of the Nina Creek group basalts indicates that they were erupted in an ocean-floorsetting, either along amid-ocean ridge, or withina back-arc or marginal basin. Chemical data alone cannot differentiate these possibilities. These diagrams, when used in conjunction with other geological information, will suggest which of the settings is the most plausible. Volcanic andsedimentary rocks of theNina Creek group suggest a back-arc basin flanked by the ancestral Figure 22. Plotof Ti Zr for Nina Creekbasalts and versus North American margin. Thebulk of the sedimentary gabbros. D, B=ocean-floor basalts; A, B=low-potassium tholeiites, A, C=calcalkaline basalts (afterPearce and Cann, rocks are argillites andcherts, indicative of quiet, deep 1973). water sedimentation. The basalts are pillowed or massive and typical of ocean-floor basalts. Although most of these rocks support formation in a deep, oceanic environment, parts of the Mount Howell succession contain minor, but important, sequences of polymict sandstones, wackes and conglomerates. The presence of these clastic rocks indicates a nearby high-energy source. Someof the wackes are very quartz rich and suggest a continental origin, presum- ablyNorth America. Sandstones inthe BlueGrouse r. 0 Mountain area are rich in volcanic fragments and contain i= rare metamorphic clasts. These rocks couldnot have been derived from the east as the Precambrian basement was buried deep below the miogeocline during thisperiod, and there are no thick successions of mafic volcanics within miogeoclinal stratacapable of generating thismaterial. Thissuggests awestern source.Clast types indicatea source area rich in volcanic material. An island arc, possibly floored by continental material, would be an environ- men1 capable of producing such high-energy deposits. Figure 23. Plot of TiO, versus YINb for Nina Creek basalts Arc-type deposits contemporaneouswith those of the and gabbros (after Floyd and Winchester, 1975). Nina Creek group within Quesnel rocks of the map area are assigned to the Lay Range assemblage (Roots, 1954; Rossand Monger, 1978;Ferri et a!., 1992a.b. 1993a,b). Tuffaceous sequences within the Lay Range assemblage are similar to the volcaniclastic sequences in the Mount Howell succession. High-energy rocks of the Lay Range assemblage may represent material shed off an active arc to the west (back-arc sediments) which was covered by subsequent Triassic volcanism. It is suggestedthat the Nina Creek group was deposited within a back-arcbasin marginal to North Americathat resulted from back-arc spreading during formation of the arc. The regional tectonic implications of this interpretation are further discussed in a later chapter (Geological Synthesis).

MANSON LAKES ULTRAMAFICS (Informal, Mississippian to Permian?) TheManson Lakes ultramafics were originally Figure 24. Plot of P,O, versus Zr for Nina Creek hasalts and grouped with the Trembleur intrusions, a name proposed gabbros (after Winchester and Floyd, 1976). by Armstrong (1949) to describe a series of ultramafic

40 Gobbro A W39

Figure 25. Extended trace element plot for Nina Creek basaltsand gabbros. This flat signature is typical for mid-ocean ridge basalts,see text for details. These are normalized to mid-ocean ridge basalt using values from Pearce (1982); %=I20 ppm: K,O=O.IS%: Rb=2 ppm; Ba=20 ppm; Th~ll.2ppm; Ta=O.IR ppm; Nb=3.5 ppm: Ce=IO ppm: P,O,=O.IZ%; Zr=90 ppm: Sm=3.3 ppm: TiO,= 1.5%: Y=30 ppm; Yb=3.4 ppm; Sc=40.11 ppm Cr=2511 ppm. bodies exposed within the CacheCreek Group. These seen elsewhere.Due to theirhighly dismembered and bodies are now known to be slivers of oceanic crust within altered state within the fault zone it is uncertain whether the Cache Creek Group (Monger, 1984; Ash and Arksey, theserocks represent oceanic crust or Alaskan-type 1990 Ash and MacDonald 1993) and not intrusive bodies. intrusions. Alaskan-typeultramafic intrusions, such as thelarge Contacts, where exposed, are tectonized. Steep, brit- Po'laris body (Nixon et ul., 1990) and a small body north- tle fault zones are seen within theManson fault zone wrst of UslikaLake (Roots, 19541, are exposed to the (Plates 34 and 36). One body of ultramafite is separated northwest, along strike with the Manson Lake ultramafics. fromunderlying Boulder Creek sediments by a sub- Ekewhere in the Slide Mountain Terrane ultramafic rocks horizontal fault which contains kinematic indicators sug- have been interpreted as part of a dismembered ophiolitic gesting motion to the east (Plate 29). smte (Crooked amnhibolite. Antler Formation. Montgom- ery, 1978, Struik.'l988a, Rees, 1987;Anvil'alloch;hon, Tempelman-Kluit,1979). The Manson Lakes ultramafic Age and Correlation bodies are not grouped directly with the Nina Creek group The Manson Lakes ultramafic bodies maybe corre- as no relationship can be demonstrated between the two lated with the Crooked amphibolite of the Slide Mountain suites except that they are both involved in the Manson Group (Struik, 1985, 1988a; Rees, 1987). Lenses of the fault zone. The ultramafic rocks have been included within ultramafite crop out along the western margin of the Boul- the: Slide Mountain Terrane on the basis of relationships derCreek group which is inferred to be related to the

41 Snowshoe Group (see Boulder Creek group). There is a extendedthis package into the Nina Lake area and similar structural relationshipto thesouth between the includedrocks of theNina Creek group. Wheeler and Crookedamphibolite and the Snowshoe Group. The McFeely(1991) grouped these rocks with the Harper Crooked amphibolite is equatedwith the Antler Formation Ranch Subterrane which is considered to be the basement of the Slide Mountain Group, suggesting a genetic rela- of Quesnellia. Ferri and Melville (1988, 1989) and Ferri tionship between the Nina Creek group and the Manson et al. (1988, 1989)postulated the presence of Harper Lake ultramafites. Ranch rocks inthe GermansenLanding area based on The age of these ultramafic bodies is unknown but lithology and on early fossil identifications. More recently K-Ar dating of mariposite has yielded an age of 134 Ma Ferri et ul. (I 992a, h), working in the adjacent Uslika Lake (Appendix 11). There are no other metamorphic or igneous mapsheet to the northwest, described Lay Range events of the same age in the map area. assemblage volcanic and sedimentary rocks sitting above rocks of the Cassiar Terrane.Lay Range rocks in the Lithology Uslika Lake area were mapped southward intothe Discov- ery Creek valley by Ferri et a/. (1992a. b) where Nelson A series of poorly exposed lenticular bodies of ultra- et a/.(1993a. b) traced them southeastward to the Omineca mafite are exposed along theManson fault zone. These River.This mapping suggests thatall volcanicrocks bodies are small, with the largest being only a few square southwestof theManson fault zoneand north of the kilometres in area,and occur intermittently from the Omineca Riverare pan of theLay Rangeassemblage. southeastern corner of the map area. northwestward to the these rocks appear very similar to the Germansen River. Three types of ultramafitehave been Superficially Takla Group. This led Armstrong (1949). as well as Ferri recognized: serpentinite, talc-serpentine bodies and talc- and Melville (1988, 1989) and Ferri et a/. (1988, 1989), to ankerite-serpentine schists or listwanites. place them within the Takla Group. Differences between Serpentinite bodies are the most abundant; they are lithologies of the Lay Range assemblage andthe Takla essentially pure serpentine with minoramounts of dis- Group can be subtle. Rocks of the Lay Range assemblage seminated talc, ankerite and epidote which may accom- are commonly characterized by a more penetrative defor- pany quartz-calcite veining. Serpentinitesare generally mation and greater induration. Tuffs are commonlya blue- magnetic and may contain veinlets of chrysotile. These greencolour which is moreintense and somewhat dif- rocks are well exposed immediately south of the Farrell ferentthan the greyto grey-green andmaroons of the showing on the north side of the Germansen River and at Takla Group.Compositionally, volcaniclastic, rockscan the south end of a ridge approximately 8 kilometres west sometimes be distinguished fromthose of the Takla Group of Gaffney Creek. by the presence of quartz andchert clasts. Lay Range The talc-serpentine bodies are up to 50% talc which agglomerate and lapilli tuffs, by themselves, are typically occurs as either disseminated grains, fine-grained masses indistinguishable from those of the Takla Group. 0.5 to 1 centirnetre in size, or asradiating crystal masses a The overall character of Lay Range rocks is very few centimetres in diameter. A weak foliation is present in similar to the Takla Group suggesting a volcanic arc set- themore talc-richbodies. Examples of these are seen ting. Thepresence of quartzclasts within the sequence around Boulder Creek. suggests a more evolved volcanic centre or a continent as The second most abundant ultramafite type is talc- possible sources for some of the material. ankerite-serpentine schist. These rocks commonlycany Lay Range assemblage rocks form a fault-bounded mariposite, magnetite and quartzas accessories but are package north of the Omineca River and southwest of composed essentially of talc and ankerite. They are grey- Nina Lake. Numerous other faults dissect this sequence greento brownishweathering andcommonly coarsely (along Wendy andCook creeks) precludinga detailed crystalline with large (up to 1 centimetre) porphyroblasts understanding of theinternal stratigraphy. Generally, a of ankerite.Magnetite is present as finely disseminated coarse volcaniclastic section (unit MPlr2) appears to lie crystals which may comprise up to 2%of the rock. Bodies stratigraphicallyabove a package of finetuffs and of theseschists are wellexposed along a creek in the argillites (unit MPlrl). The combined thickness of these southern part of the map area, along thenorth shore of the units is difficult to determine though a minimum thickness Lower Manson Lake, north of Boulder Creek and at the of approximately 2000 metres is estimated. big bend in the Germansen River. Age and Correlotion QUESNEL TERRANE No fossilswere recoveredfrom rocks of theLay Rangeassemblage in themap area. Permian conodonts LAY RANGE ASSEMBLAGE were collected by J.W.H. Mongerfrom the LayRange (Mississippian? to Permian) assemblage in the Uslika Lake area (M.J. Orchard, per- The name Lay Range assemblage was first used by sonal communication,1991; Ferri et al., 1992a). Roots Ross and Monger (1978) for a succession of upper Pal- (1954) collected macrofossils in the Lay Range which eozoic volcanic and sedimentary rocks which are well suggested alate Paleozoic age. Some of Roots’ fossil exposed along thehigh ridges in theLay Range. These assemblagesindicate possible Mississippian lower age rocks werefirst described by Roots (1954) who traced limits. Ross and Monger (1978) recovered middle Penn- them as far south as Uslika Lake. Ross and Monger (ibid.) sylvanian fusulinids from limestones in the Lay Range.

42 The assemblage appears to be confined to the upper Pal- bearing volcaniclastics, are exposed along Evans Creek. eozoic and spans the Mississippian? to Permian periods. Pillowed basalts occur in the sequence along Evans Creek and on a ridge southwest of the creek. The pillows may Assignment of the Lay Rangeassemblage to the contain 1 to 5% augite phenocrystsup to severalmilli- Harper Ranch Subterrane is questionable (Monger et nl., metres in size.The hasalt is associated with green 1991). The fine clastics, carbonatesand cherts have some tuffaceousrocks in the upper plate of theEvans Creek similarities to theUpper Devonian to Upper Permian thrust fault. These rocks may he separated from the Evans HarperRanch assemblage in southernBritish Columbia Creek limestone (see below) by a splay of the Evans Creek (Monger cf d,IYYI), but the Harper Ranch assemblage thrust (see Structure chapter). lacks the voluminous coarse volcaniclastics which typify Lay Rangeassemblage lithologies. Smith (1974) con- Southwestof Nina Creek, unit MPlrl contains cluded that the fine sediments of theHarper Ranch coarser tuffsand lacks an abundance of argillite and cherty assemblage in theKamloops area werederived from a horizons. It also appears tolie stratigraphicallybelow di:;tal volcanic arc. Lay Range assemblage rocks in the coarser volcaniclastics of unit MPlr2. Germansen Landing area strongly indicate a volcanic arc sel:ting suggesting that the Harper Ranch assemblage may Unit MPIr2 represent more distal facies equivalents. Unit MPlr2 is best exposed along the ridges between Harper Ranch rocks locally unconformably underlie Wendy and Cook creeks.This unit is characterized by M8:sozoic rocks of Quesnellia in southern British Colum- blue-grey to grey-greenor maroon augite-plagioclase- hi;! (Monger ef u!.. lY91: Read and Okulitch, 1977). Lay phyric agglomerate to lapilli tuff with lesser amounts of Range rocks appear to lie structurally against rocks of the tuff,tuffaceous siltstone, siltstone and argillite.The Takla Group and Nina Creek group in the map area. coarser volcaniclastics of this unit exhibitthe greatest Coarse volcaniclasticand flow rocks of late Pal- similarities to coarse volcaniclasrics of the Takla Group. eoLoic age within Quesnellia north of themap area are Smallbodies of green togrey, tine to medium-grained absent or poorly exposed. Possiblecorrelatives may be gabbro are also found within this unit. present within theSylvester allochthon in the Cassiar Mountains. The uppermost part of the allochthon (Divi- EVANS CREEK LIMESTONE sion Ill) is a volcanic arc sequence (Nelson and Bradford, (Perrno-Triassic) 1987,1989. 1993; Nelson cf 1988) which contains a!., The Evans Creeklimestone outcrops on the mafic to felsic volcaniclastics and flows. chert, limestone, ridge north of Evans Creek and extends northwestward across ar~dlite,sandstone and tonalite of Mississippian to Per- the Omineca Riverwhere it is truncated by faults and mian age. The mafic volcanics and epiclastic sequences sandwiched between rocks of the Lay Range assemblage. he;u some gross similarities to the Lay Range assemblage. It is some 500 metres thick and present only in the north- The intermediate to felsic volcanism evident in Division centralpart of themap area where it is uplifted on a 111 is not recognized in the Lay Range assemblage and, if southwest-verging thrust fault. The limestone is generally the two arerelated, Division Ill mustrepresent a more a massive, cliff-forming unit although bedding can some- evolved arc. times he seen as faint platy partings. It is grey to light grey on fresh surfaces and dark grey to grey-brown weathering. Unit MPIrI It is finely recrystallized and has a slightlyfetid odor when broken. Commonly it is cut by numerousquartz-calcite This unit is chardcteri7ed by blue-grey to grey-green wins of various orientations. tuff to volcanic sandstone or conglomerate together with tuffaceoussiltstone. dark grey to greenishargillite and Age and Correlation silty argillite,siltstone and minor lapilli tuff and grey- hrown to hrown cherl to chertyargillite. Volcanic sand- Several conodont collections were recoveredfrom stone and conglomerateare characterized by clasts of north andsouth of the Omineca River. The age range basalt (sometimesaugite-plagioclase phyric),argillite, suggested by all suites is Middle Permian to Late Triassic chert and quartz. Lapilli tuff contains a predominance of (Carnian see Appendix I).Some of the individual samples augite plagioclaseporphyry clasts with rarechert and indicate a definite Permian age (fossil locality 34) whereas argillite clasts. Locallyone finds small bodies of green, others are Middle to Late Triassic (fossil localities 32. 35, fine to medium-grained gabhro. 37, 38). Several samples have a mixed faunal assemblage. The Nina Creek and Goat Creek valleys are underlain Locality 33 has both Middle to Late Permian and Middle by a fault-boundedpackage of this unit which is domi- Triassicsuites (M. J. Orchard, personal communication, naled hy dark grey to grey sheared argillites, grey-green 1993). Sample 31 containsMiddle Permian and Early siltstones and cherty beds. Minor lithologies include tuff Triassic fossils, and almost all conodonts from locality 36 and lapilli tuff. These rocks can he traced southeastward to indicate a Carnianage except forone which is Early the Omineca River and are assumed to be faulted against Triassic. theGilliland tuff, though a stratigraphic contactis not Themixed faunal assemblages suggest several mled out. possibilities: Fine tocoarse volcaniclasticsand tuffaceous silt- reworking of older conodont-bearinglimestone and stones, together with minor argillaceous rocks and quartr- incorporation into younger carbonate,

43 samplingacross a highly condensed sequence which Age and Correlation encompasses the Permo-Triassic boundary andor a Conodont collections from the Takla Group indicate a disconformity at this boundary. Middle to Late (Carnian) Triassic age for the Slate Creek Conodontmorphology does not indicate reworking succession. The succeeding mafic volcanicsof the Plughat (M. J. Orchard,personal communication, 1993) which Mountain succession are assumed to he Middle to Late suggests sampling along a condensed sequence containing Triassic in age as are similar rocks along the Quesnel belt the Permo-Triassic boundary. The nature of this boundary (Armstrong,1949; Bailey, 1978, 1988, 1989; Struik, is not known. Sampling south of the Omineca River was 1988b; Panteleyev, 1988). Lower Jurassic volcaniclastics near the stratigraphic top of the unit but there appearedto and sediments are found within the Takla Group in the be no variation in lithologyreflecting the age change QuesnelLake area (Bailey, ibid). Theseheterolithic suggested by some of the mixed faunal assemblages. If feldspar-rich and analcite-bearing volcanics are unlike the thisunit contains the Permo-Triassic boundary then the volcaniclastics in theGermansen Landing area. Lower assignmentof this limestone toeither the Lay Range Jurassicvolcanic sequences have also been recognized assemblageor the Takla Group becomes problematic. withinthe Takla Group in thearea (Armstrong, 1949: Because of the ambiguous fossil control, we suggest that Roots, 1954; Nelson et a/.. 1991, 1993a) suggesting that this limestoneremain as a separate unit until definite the Plughat Mountain succession includes Lower Jurassic stratigraphic relationships are determined. strata. Lower Jurassic lithologiesin the area are dominated byheterolithic volcanic breccias rich in feldsparwhich, Thick,massive Permo-Triassic limestones are rare again, is not typical of the Takla Group in the map area. within the Quesnel Terrane. Early to Late Permian limestone, several hundred metres thick,is found in the Harper Inthe Germansen Landing area, two broad facies Ranch Group in southern British Columbia (Orchard and belts have been recognized within the Takla Group, corre- Forster,1988; Nelson andNelson, 1985). Nelson and sponding to the Plughat Mountain and Slate Creek succes- Bradford (1993) describe slivers of Early, middle and Late sions. To the east, fine-grained clastic rocks of the Slate Permianlimestones in Division I11 ofthe Sylvester Creek succession give way westward and become inter- allochthon.Although these rocks are part of the Slide fingeredwith coarser clastics and volcaniclastics of the Mountain Terrane, elements of Division 111 are quite simi- Plughat Mountain succession (Figure 27). This relation- lar to those of the Harper Ranch Subterrane. ship indicates that the Slate Creek and Plughat Mounrain successionsare essentially the sameage. In theGer- mansen Lake area, coarse volcaniclastics and flows of the TAKLA GROUP PlughatMountain succession rest in sharpcontact on (Middle Triassic to Lower Jurassic(?)) argillites of the Slate Creek succession. This relationship indicates that the local volcanic centre probably lay to the Armstrong (1949) named the Takla Group after its west. Very similar facies relationships have been demon- extensive exposure in the Takla Lake area. He applied the strated within the Takla and Nicola Groups south of the name to two beltsof mafic volcaniclastic rocks and related map area (Nelson et a/., 1991; Struik, 1988b; Rees, 1987; sedimentsexposed on either side of theCache Creek Monger et al., 1991). Group in the FORSt. James area. The type locality is west of the Pinchi fault and is thus part of the Stikine Terrane, Argillites similar to the basal Slate Creek succession extendfrom the study areasoutheastward to southern Takla rockswithin the Manson Creek andGermansen BritishColumbia (Table 4). Immediately to the south, Landing area are part of the Quesnel Terrane. These rocks Nelson et a/. (1991)report basal slates, argillites and represent an island arc which spans the Middle Triassicto minor volcanically derived sediments which they call the Early Jurassic time periods (Souther, 1991). This belt of Rainbow Creek formation. These include quartzose sands volcanics and related sedimentary rocks extends the length of possible cratonic origin and appear similar to the lower of the Canadian Cordillera and includes the Slocan Group, parts of the Slate Creek succession. Argillites, tuffaceous Rossland Group (in part) and Nicola Group to the south, sediments and coarser volcaniclastics of the inferred youn- and the Shonektaw and Nazcha formations north of the ger Inzana Lake formation correlate with the upper Slate study area. Creek succession. The Takla Group in the map areahas been subdivided The Slate Creek succession is equivalent to the Mid- intotwo successions; thelower Slate Creek succession dle to Late Triassic black phyllitein the Quesnel Lake area composed of phyllite, argillite, limestone and lesser tuffs, (Rees,1987; Bloodgood, 1987, 1988, 1990; Struik, mafic volcanics and coarser, volcanically derived epiclas- 1988b). The black phyllite unit has similar lithologies, age tics; and the upper Plughat Mountain succession whichis a andfacies relationships with the western Takla Group thick sequence ofaugite-bearing, mafic and intermedi- volcanicsand also containsmafic flows as seen in the ate(?) calcalkaline to alkaline pyroclastic rocks, massive MansonCreek area (Rees, 1987; A. Panteleyev, 1990, flowsand lesser epiclastic rocks (Figure 26). The total personal communication). thickness is at least 5 kilometres in the southwestern half of the map area. South of Quesnel the Slate Creek successionis probably equivalent to Carnian to Norian phyllites, limestones The Takla Group is in faultcontact with the Nina and minor sandstones of the Slocan Group (Klepacki and Creek group. Wheeler,1985).

44 - 3- aeq*v* Volcanic breccia, agglomerates, tuffs 3 Massive,*augite *feldspar. phyric flows. Agglomerate,lapilli tuff, voicanic

Tuff.volcanic sandstone 0Volcanic siltstone. tuffs Pillowedbasalts W2Y!* Ouarizose sandstone

Limestone __ I,=I Calcareous 2 aArgillite

Plugh at Mountain Succession

...... ,. 7

.. tl "_" .. I ""_.,...... _"" I/ ""_""_ . ""_ ......

""" ...... """

Slate Creek """ Succession :cession "" """ ""_ Evan's CreekLimestone

. . , ...... ""

6oo ] . 0 t""4 m.tr.r l (b)

Figure 26. Schematic stratigraphic columns of the Takla Group and Evans Creek limestonewithin the study area. (a) Composite st,-atigraphic diagram involving outcrops east and southeast of Plughat Mounlain where unit I of the Plughat Mountain succession is present. (b) Schematic stratigraphic column in the Evans Creek area showing position of the Evans Creek limestone.

45 DiAGRAMATlCREPRESENTATION OF THETAKLA GROUP NE

PlughatMountain I Succession PlughatMountain

a A nD

Tuff,argillite epiclasticsShale, m] m,-F--I: Basaltic to andesitic flows Agglomerate, tuff Agglomerate and volcanic abreccia Figure 21. Diagram showing facies relationships between various units of the Takla Group within the study area.

TABLE 4 CORRELATION CHART OF TAKLA GROUP ROCKS WITHIN THE STUDY AREA AND SIMILAR ROCKS TO THE SOUTH.

NATiON RIVER QUESNEL LAKE QUESNEL LAKE MOUNTAINS

8& Bale& 7987-89; (Struik. ?988b) Bloodgood, 7988)

IPlughat Mountain Lower Takla Norian succession Group I

Carnian Slate Creek phylliteBlack formation succession 7 L I I Anisian I I 1

46 The black phyllite and Slocan Groupboth rest uncon- They are sometimesgraphitic and contain abundant, finely formably on volcanic and ultramafic rocks equivalent to disseminatedpyrite. The argillites are sometimes quite theNina Creek group (Klepacki and Wheeler, 1985; siliceousand are interlayered with dark grey to grey McMullin et al., 1990). Thisrelationship was not observed graphiticsiliceous argillite or chert.Minor limestone in Ihe map area. ~- sequences (less than I metre) or beds 1 to 30 centimetres Augite-bearingmafic, calcalkaline to alkaline vol- thick are sometimes present. canic rocks of the Plughat Mountain succession aretypical Thin layers(less than 30 centimetres) of quartz of the most volumetricallyimportant lithologies of the wacke and quartz-rich siltstone to very fine grained sand- Quesnel Terrane. They are equivalent to the Shonektaw stone were observed within the argillites. They are grey to and Nazcha formations north of the study area (Gabrielse, light brown weathering and contain no internal sedimen- 19158).Immediately south of the map area, recent mapping tary structures. These quartz-rich clastics occur within the by Nelson et a/.. (1991) has delineated a mafic to inter- Manson fault zone. mediatevolcanic and volcaniclastic sequence calledthe Witch Lakeformation which is also equivalent to the Buff-weathering, dark grey, massive limestone up to PlughatMountain succession (Table 4). Unit I volcanic 5 metresthick is found along Slate Creekand on Con- sediments and tuffs of the Plughat Mountain succession naghan Creek.This limestone is typicallyfinely crys- are equivalent to lnzana Lake formation epiclastics. talline although patches are coarsely recrystallized. In the Quesnel area, the Plughat Mountain succession A northwest-trending band of mafic volcanic rocks is is equivalent to the lower mafic and intermediate volcanics mapped within the succession north of Mount Gillis. It of the Takla Group which are of Norian age (Panteleyev, terminatesto the northwest against the Germansen 1987, 1988. Panteleyev and Hancock. 1989, Bailey, 1988, batholith and can be traced to the southeast for approx- 1989). imately 5 kilometres.A continuation of these volcanics In southernBritish Columbia, Upper Triassic to may be present to the northwest, along the Manson River, Lower Jurassicvolcanic rocks of Quesnellia are repre- where several outcrops of hornfelsed, pillowed volcanics senltedby theNicola Group. It is subdivided into three are exposed. Thin maficvolcanics flows within slates belts; a western belt composed of basic to felsic pyroclas- alongthe south side of theGermansen River arealso believed to be pat of this sequence. tic and volcaniclasticrocks, a central belt of porhyritic augite basalt. and andesite flowsand brecciasand an At Mount Gillis the volcanics are up to 400 metres eastern belt composed of central belt volcanics which thick and massive to pillowed (Plate 24). They commonly interfinger with sedimentaryfacies to the east(Preto, contain a weak to moderate flattening fabric which paral- 19?7; Mortimer, 1987). The Plughat Mountain succession lels the boundary of the unit. Pillows are stretched parallel is equivalent to rocks of the central and eastern belts. to this fabric. Theserocks become homfelsed within 2 to 3 kilometres of the Germansen batholith and contain biotite, Shte Creek Succession actinolite,chlorite, plagioclase, quartz, epidote and (Informal, Middle to Upper Triassic) opaques. Epidote and calcite veining is not uncommon. Maficminerals are randomly distributed to partially Lithology: The Slate Creek succession comprises aligned. This weak fabric is a recrystallization of an earlier argillite,slate, siliceous argillite, limestone, lithic tuff, fabric. mafic volcanics and volcanic siltstone with lesser chert, volcanicwacke, volcanic sandstone, volcanic conglome- ratt! to breccia and rarr quartz-rich siltstone to sandstone. It typically crops out on theeastern side of the Takla Group and can be traced from the GaffneyCreek area northwestward toward Nina Creek. It is the dominant unit of the Takla Group in the southern part of the map area but thins to thenorthwest. The succession is 500 to 1000 metres thick northwest of the GermansenRiver and at lea!rt several kilometres thick southeast of Mount Gillis. It is involved in theManmn fault zone and occursas xquences of crumpled slates and argillites which are well expsed along Slate Creek. Theargillites usually contain a spaced cleavage (from a few rnillimetres to several centimetres) which oftenbecomes penetrative within the Mansonfault zone. The upper part of the unit is interlayered with lithologies of the Plughat Mountain succession in theeastern and northeastern parts of the Takla Group but is believed to be in sharp contact with the volcanics ofthe overlying Plughat Mountain succession in the Mount Germansen area. Plate 24. Pillowed basalt of the Slate Creeksuccession near The argillites are thin to moderately bedded, cream to Mount Gillis. This unit canbe traced for approximately 10 ruslyweathering and typically grey on freshsurfaces. kilometres in the southeastern pan of the study area.

47 Several kilometres along strike to the southeast, simi- quartz and chert clasts. The relationship of thisunit to lar greenstones are associated with weakly to moderately otherunits of thePlughat Mountain succession is not foliated,coarsely crystalline gabbro and were seen in known. several outcrops. They are composed of coarse actinolite The preceding section on the Lay Range assemblage and plagioclase with traces of quartz. outlines the similarities between lithologies of the Takla Tuffs beds in the Slate Creek succession are cream to Group and Lay Range assemblage. It is sometimes impos- beigein colour, thin to moderately bedded and fairly sibleto distinguish between the two successions when siliceous. They occur both interbedded with the argillites distinctive characteristics are lacking. The recognition of and in sections 1 to 10 metres thick. The coarser tuffs have Lay Range rocks geographically between Takla and Nina discernibleclasts of feldspar, feldspar porphyry, and Creek lithologies in the northwestern part of the map area rarely, argillite and quartz. hasled to a re-evaluation of similarsequences in the region west of Manson Creek. Some areas of coarser tuffs Thinto thickly bedded volcanic sandstone, con- and epiclastics have characteristics similar to Lay Range glomerate and some volcanic breccia are exposed in the lithologies but for the most part these rocks share more upperpart of thesuccession. The sandstone clasts are similarities with the Takla Group. Deformation and altera- subangular and composed of feldspar crystal fragments, tion within the Manson fault zone has made this distinc- feldsparand augite feldspar porphyries, augite crystal tion somewhat more difficult. fragments and rare quartz and argillite. Clasts in the conglomerates and breccias are predominantly feldspar augite Unit 1: Unit 1 is characterized by tuff tovolcanic porphyries, aphanitic volcanics and minor argillite. sandstoneand conglomerate, tuffaceous siltstone and Discussion: Basaltswithin lowermost argillite and argillite. The best exposures areon small knolls north and siltstone of the SlateCreek succession are thought to south of theconfluence of theGermansen and South represent submarine flows within the Slate Creek basin Germansen rivers. Theunit is over I kilometre thick in the andnot tectonically emplaced slivers of NinaCreek eastern part of the map area but pinches out westward, basalts. toward Germansen Lake where there is an abrupt facies transition. It is tempting to correlate these mafic volcanics with Tuff is intermixed with epiclastic or more reworked shearedvolcanics, amphibolite and ultramafite of the volcaniclastics. These rocks are grey to dark grey-green, Crooked amphibolite (Slide Mountain Group) to the south. This unit is found intermittently at the base of the black massive, poorly sorted and typically coarse grained with isolated lapillis or cobbles. The majority of the clasts are pbyllite unit in the Quesnel Lake area, and is in structural pyroxene feldspar porphyries of various types, although contactwith it androcks of theBarkerville Terrane hornblendefeldspar and feldspar-phyric clasts are also (Struik, 1985, 1988a; Rees, 1987). However, in the map present. Pyroxene, feldspar and hornblende crystal frag- area,these mafic rocks are bounded on both sides by ments are abundant. All clasts are angular, subangular to sediments of the Slate Creek succession which is not a subrounded and the lithic clasts are typicalof Takla Group typicalstructural relationship for the Crooked amphi- lithologiesfarther west. The matrix is typically finely bolite. Furthermore, internal primary structures are lacking crystallinechlorite although some fractures contain in the Crooked amphibolite in the Barkerville area and the prehnitelpumpellyite infills. fabric is better developed than that observed in volcanics of the study area. Massive to poorly sorted volcanic conglomerates and brecciasare typically matrix supported, with the matrix Age: Conodontsrecovered from limestones in the beinga volcanic sandstone as described above. These SlateCreek succession indicate a Middle (Ladinian) to coarse volcaniclastic rocks grade into lapilli tuffs. Clasts Late (Carnian) Triassic age. range from 0.5 to 30 centimetres across and can he polymict.They are composed of vesicularto amygdaloidal Plughat Mountain Succession basalts,pyroxene and hornblende feldspar porphyries, (lnforma~Upper Triassic) feldspar porphyries and rare chert and argillite. The vol- canicclasts are identical to Takla volcanic lithologies Rocks of the Plughat Mountain succession represent fartherwest. These conglomerates are locally pen- the bulk of the Takla Group in the map area. They are etratively deformed as indicated by the presence of flat- predominantly mafic pyroclastic rocks, mafic flows and tened clasts. epiclastic rocks of volcanic origin. The succession is some 4 kilometres thick and has been subdivided into four units. Thelower parts of the unit contain sections of The first three units appear to comprise a crude stratigra- argillite and tuffaceous beds similar to those described in phy and are represented by: a lower unit composed pri- the Slate Creek succession. These finer grained lithologies marily of distal tuffs mixed with volcanic sandstone, con- contain a spaced cleavage which is not well developed in glomerate and breccia, siltstone (tuffaceous) and argillite; the conglomerates. a middle unit ofcoarse pyroclastics (agglomerates, The coarser epiclastics bear some similaritiesIO Lay tuffaceous breccias and lapillistones) and mafic flows with Range assemblage lithologies, particularly the presence of subordinate tuffs; and an upper unit made up of volcanic rare chert and argillite clasts. This does not exclude them sandstone and conglomerate. Unit 4 is composed of mar- from the Takla Group, as it contains some quartz-bearing oon flowsand volcaniclastics with minor hut characteristic tuffs(Unit 4), buta cautionary note is needed here.

48 subdividedinto four broad subunits: (2a) is composed predominantly of pyroclastics - agglomerates. tuffaceous breccias, lapillistones and volcanic sediments with lesser massive flows, (2b) comprises predominantlyflows and coarse pyroclastics with lesser fine tuffs, (2c) is represented by well-bedded tuffs to lapilli tuffs and (2d) characterized by maroon bladed-feldspar flows. Subunits 2a and 2b are volumetrically the most abundant. Augite-bearing, massive basalts are more abundantin the lower, more easterly exposures of this unit whereas in the upper, more westerly parts, feldspar-phyric flows of a more intermediatecomposition arecommon. Faintout- lines of pillows were observed in massive augite-phyric basalts along the ridge northeast of Evans Creek. The volcanics of unit 2 are commonly augite phyric with lesser augite or hornblende feldspar porphyries which may containserpentinized phenocrysts of olivine. They tend to he green, grey-green or grey to brown. The more maficvolcanic rocks are slightlymagnetic. Individual flows and agglomerates vary from a few metres to tens of metres thick. Pyroxene phenocrysts form up to 30% of the rock and are up to a centimetre in length. Maroon to brown, aphanitic, amygdaloidal (calcite- filled) basalts are also present within this unit. They are well exposed on aridge 2 kilometressouth of Plughat Mountain. Flows tens of metres thick are capped by flow- top breccia which may be infilled by micritic limestone. In the vicinity of the Germansen batholith, biotite and actinolite are developed within the volcanics. These vol- canicsgenerally do not displaya penetrative fabric but rather a weak foliation or cleavage, produced by the subparallel alignment of actinolite and biotite crystals. Tuffaceous siltstones and argillites with lesser lapilli tuffs are foundapproximately 3 kilometres west of Plughat Plate 25. Augite and plagioclase-phyric agglomerate of the Plu- Mountain.between Paquetteand Evans creeks. These ghat Mountain succession, nonh of Plughat Mountain. rocks are part of a sequence several hundred metres thick but do not extend along strike, indicating a facies transi- Characteristics resembling the Lay Range assemblage are tion or fault. best seen in sections immediatelynortheast of thecon- Approximately 8 kilometres west of Plughat Moun- fluence of the Germansen andSouth Germansen riversand tain is asequence of coarsely bladed, maroonfeldspar- in the area around the QCM showing. South of the Ger- porphyry flows and agglomerates (2d) which are distinct mansen River the same unit appears quite Takla-like and from the other porphyritic volcanics in the Takla Group. seems to grade eastward into finer tuffs and epiclastics of The feldspars are up to a centimetre long, are generally thte Slate Creek succession which has yielded an Upper sericitized and comprise upto 20% of the rock. Only afew Triassic conodont. If these rocks are, in part, Lay Range exposures ofthis rock type were seen and the extentof this assemblage it is difficult to separate them. unit is uncertain. Unit 2: Unit 2 is composed predominantly of augite Grey, finely crystalline limestone in the upper part of and feldspar-phyric basalt to basaltic andesite. These vol- this unit crops out onthe northeastern shore of Germansen canicsare dominated by coarse pyroclastics(Plate 25) Lake.It is up to 25 metresthick and has been traced withlesser massive flows and finer tuffs. The best discontinuously for several kilometres. Itis generally mas- exposuresare north and south of GermansenLake, sive hut in some localitiesbedding is apparentin thin although it extends into the central pm of the map area, discontinuous, darker grey and coarser grained layers. south of the Omineca River. The thickness of the unit Thin (less than 1 metre) hornblende porphyry dikes varies from 2 to 3 kilometres. Its contact with unit 1 is were mappedcutting thevolcanics of unit 2 at several generallygradational. East of PlughatMountain, localities. They are dark green togrey-green in colour with toffaceous breccias of this unit give way eastward, over a up to 20%acicular hornblende crystals which may broad interval, to tuffs, lapilli tuffs and epiclastics of unit approach 1 centimetre inlength. Thin dikes or irregular 1 In contrast, its contact with the Slate Creek succession bodies of diorite intrude the volcanics of unit 3. These south of Germansen Lake is very sharp. Unit 2 has been bodies are only 5 or IO metres in diameter and are com-

49 posed of subequal, fineto medium-grained plagioclase indicatethat evenmassive-appearing samples are frag- andpyroxene. They are also exposed in a fewother mental in nature. All samples are of prehnite-pumpellyite localities such as south of Germansen Lake. Their rela- or lower metamorphic grade. Some samples are strongly tionship to the volcanics of unit 2 is not known. altered and were not plotted on the diagrams. Numerous Unit 3: Unit 3 is apoorly exposedsequence of majorand trace element discrimination diagrams were massive to thickly bedded,dark grey togrey, volcanic produced from these data(Figures 28 to 37). Most of them sandstone, conglomerate and tuff exposed in a synclinal are similar to those used to describe Nina Creek basalts core centred on Germansen Lake. The conglomerates are and the reader can easily contrastthe chemistry of the two matrix supported with the clasts consisting of porphyries suites of rocks. similar to those in unit 2. The thickness of the unit, based Based on silica content the Takla volcanic rocks are on structural cross-sections, is estimated to he upwards of basaltic to basaltic andesite in composition and alkalineto 1 kilometre. subalkaline in character. A plot of total alkali versus silica Unit 4: Unit4 isexposed south of theOmineca (Figure 28) showsthe alkaline biasof these rocks which is River, along the western margin of the map area. It has typical of the entire belt. Another characteristic is their many similarities to the other units of the Plughat Moun- slight potassium enrichment. The subalkaline basalts are tain successionbut is distinguished by thepresence of dominantly calcalkaline (Figure 29). Figures 28 and 29, well-bedded tuffs with rare quartz clasts. It has been subdivided into two sequences, an apparently lower succession dominatedby coarse volcaniclastics andflows of basaltic composition (4a) and an upper package of finer, well-bedded tuffs, tuffaceous siltstones and agglomerate. Coarse volcaniclastics and flows are maroon to dark grey to green andmay be vesicular to amygdaloidal. These volcanicsare typically aphaniticto slightlyporphyritic with 1 to 10% phenocrysts. Typically augite is subordinate with feldspar being the dominant phenocryst. Tuffs, lapilli tuffs and tuffaceous siltstones are maroon to grey-green in colour, well bedded and in sections up to 150 metres thick. Tuff layers can he up to several metresthick and display gradational bedding. Coarse agglomeratichorizons can he found within these tuffaceous sequences. The well-bedded tuff sections are also locally characterized by the presence of angular to subangular clasts of quartz which can comprise up to 1 or 2% of the rock. The relationshipof unit 4 to otherunits of the Plughat Figure 28. Plot of total alkali versus silica for Takla Group Mountain succession is not certain. It shares many charac- basalts (after Irvine and Baragar, 1971). teristics with the maroon porphyritic basaltsof unit 2 but a directcorrelation is not possible. This unit isseparated from the unit 2 by an assumed fault. Age: Thereis no fossil controlon the age of the Plughat Mountain succession in the map area. Limestone sequences within it appear very similar to Camian carho- A nates inthe SlateCreek succession.Armstrong (1949) collected macrofossils from severallocalities alongthe Quesnel belt indicating a Late Triassic to Early Jurassic age for rocks equivalent to the Plughat Mountain succession. It is postulated to heNorian based on its similarity to Norian volcanics south of the map area (Panteleyev and Hancock, 1989; Bailey, 1988; see also introductory sec- / *\ tion on the Takla Group).

Chemical Composition and Tectonic Significance of Takla Basalrs CALCALKALINE

Major and trace elementanalyses were obtained from No20 + K20v v v v \/ \/ VI M90 17 samples of Takla Group hasalts within the map area. Samples were collected from massive or brecciated flows of unit 2 and their locations are shown in Figure 17. Care Figure 29. AFM plot of subalkaline Takla Group basalts (after wastaken tosample massive flows, hut thin sections lrvine and Baragar, 1971).

50 Ti / 100 Ti / 100

Figrlre 30. Ternary plot OS Ti/100 - Zr - Yx3 for Takla Group Figure 31. Ternary plot of Ti/100 - Zr - Sr/2 for Takla Group hasalts. B=ocean-floor hasalts: A. B=low-potassium tholeiites: basalts. Thelinear trend of data from thestrontium apex is B, C=calcalkaline hasalts: D=within-plate hasalts (after Pearce probably a result of alteration. OFB=ocean-floor basalts: and Cann, 1973). IAB-island-arc basalts; CAB=calcalkaline hasalts (after Pearce and Cann, 1973).

I2000 -

E - 9000 - F 6000 -

3000 -

0 25 50 75 100 125 175150 200 225 zr bml)

Figure 33. Plotof Ti v~rsusZr for TaklaGroup basalts. D, B=ocean-floor basalt: A. B=low-potassiumtholeiite: A, C=calcalkaline basalt (after Pearce and Cann, 1973). Figure 32. Ternary plot OS TiO, - MnOxlO - P,O,xlO for Takla Group hasalts. OIT=ocean-island tholeiites: MORB=mid-ocean ridgl: basalts; lAT=island-arc tholeiite: OIA=ocean-island alkaline basalt: CAB=calcalkaline basalt (after Mullen, 1983). Plots of TiO, versus Y/Nb and P,O, vmws Zr (Fig- ures 35 and 36) alsoshow thealkaline nature of these together with other majorelement diagrams not shown basaltic rocks. On Figure 35, the discrimination of alkalic here.display a significant amount of scatter,indicating fromtholeiitic basalts is based on the yttriudniobium majorelement remobilization during regionalmetamor- ratio, which is less that I for alkalic rocks. Approximately phiun or weathering. Other minor and trace element plots half the samples plot on or below this line. were utilized in an attempt to overcome this problem. As Tectonic discrimination diagrams of Pearce and Cann can be seen in thesucceeding diagrams the amount of (1973) andPearce (1980) utilizethe elements titanium, scatter is as great, or greater than in themajor element zirconium yttrium and strontium (Figures 30, 31, 33 and plots.This probably reflectsthe variablenature of the 34). These diagrams. when taken together, favour an arc Takla Group (i.e., island arc to back-arc basin) and possi- setting for the Takla volcanics. Data points on Figure 31 bly the composition of the basement. are relatively scattered (due to the mobility of strontium

51 100 I I I I I I I I I I I I I I I I

Figure 31. Extended trace element plot for Takla Group basalts and basaltic andesites of the study area. This pattern is indicative of basaltserupted within island-arcs. Normalized against mid-ocean ridge basalts using values from Pearce (1982); %=I20 ppm;

K,O=0.15%; Rb=2 ppm; Ba=20 ppm; Th=0.2 ppm; Ta=O.18 ppm; Nh=3.5 ppm; Ce= IO ppm; P2 05- -0 ' 12%;Zr=W ppm; Smz3.3 ppm; TiO,=1.5%; Y=30 ppm; Yh=3.4 ppm; Sc=40.0 ppm Cr=250 ppm. 52 1 one for classic island-arc tholeiites) or mixing of magmas II fromtwo separatesources. Pearce (1983) indicates that continentallithosphere contamination of arc lavas (i.e.. arcsdeposited on continental crust) can causea ..3.I similar, and more dramatic, enrichment in these elements. Pearce (ibid.)also presents a diagram which discriminates betweenarcs developed on continental or oceanic lithosphere on the basis of zirconium and yttrium ratios (Figure 38). Data for Takla rocksfrom the studyarea clearly plot within the continental-arc field. This suggests that the Takla arc may be built on continental lithosphere. There is no evidence for thiswithin the map area but indirect evidence exists in the Lay Range, immediately to the northwest (see under Nina Creek groupand chapter on Metamorphism). Chemical trends documented here are in very good agreement with those previously reported in southern Brit- ish Columbia (Morton, 1976;Preto, 1977; Fox, 1977; Figure 36. Plot of P,O, versus Zr for Takla Group basalts (after Winchester and Floyd. 1976). Mortimer, 1986, 1987; Bailey, 1978; Lu, 1989) and in the study area (Meade, 1977). Many of the trace element and rare earth plots indi- during low grademetamorphism), but fall within the fields cate calcalkalinemagmatism related to arcvolcanism, definedas calcalkaline hasalts to island-arcbasalts. however, other diagrams suggestwithin-plate signatures Figure 33 (Zr vs Ti) also indicates the calcalkaline nature (;.e., ocean-islandbasalts or rift volcanism). The latter of these basalts but the spread of data also fallswithin the trend may suggest a more complex origin for these vol- field designating ocean-floor hasalts. Figures 30 and 34 canic rocks. Mortimer (1987) obtained similar variations show the calcalkaline arc nature of these rocks and also forNicola volcanics in southern British Columbia. He theirtrend toward within-plate basalts (i.e., alkalic shows that volcanics havingwithin-plate characteristics oceanic-island basalts). This latter trend led some geolo- have affinities with volcanicsthat are distinctly cal- gists working in the southern Quesnel belt to favour a rift calkaline and arc related. He points outthat the two groups environment (Morton, 1976; Preto, 1977). are interbedded (as seen in the study area) and rulesout the The titanium content of island arcs tends to be low, possibility that arc volcanism may have been periodically interrupted by rifting as suggested by thewithin-plate lees than 0.7% TiO, (Perfit ef ul., 1980), a characteristic displayed by someof the dataplotted on Figure 35. basalts. These lavas indicate a transition between arc and Mullen (1983) uses this trend in a ternary plot of Ti0,- within-plate volcanism which may be related to back-arc P:,O,-MnO (Figure32) and these data show the spreading. Funhermore, Monimer states that the chemical calcalkalineisland-arc nature of thesevolcanics. Takla trend of volcanics from western to eastern belts suggests ba.salts with anomalous TiO, values are clearly seen on eastward subduction. Figures 30, 33 and 34 where they produce distinct clusters 10 I separate from the other basalts. These basaltsoriginate I I fromthe Plughat Mountain regionand may represent localized.anomalous magmatism with within-plate characteristics. Finally, extended trace element data were obtained for selected samples of the Takla Group. These data are shownon Figure37. The relatively flatslope that is characteristic of MORB composition is lacking.Instead the pattern is typical of island-arc volcanics. The elements strontium through to thorium and phosphorous show an enrichment relative to tantalum and niobium which is typical of island-arc basalts (Pearce, 1982). Another fed- *l ture of island-arcbasalts is the low abundance(below unity) of zirconiumthrough to scandium relative IO MlORB values. These basalts alsoshow an overall enrichment of stlrontium to samarium relative to true island-arc tholeiites LodW (see Figure 1 of Pearce,1982). Such apattern can be Figure 38. Plot of log (Zrpi) versus log Zr (from Pearce, 1983). produced by anomalous volcanic-arc basalts. This anoma- Thisdiagram distinguishes between arc volcanics erupted on lous character may result from a mantlesource which Oceanic crust and those erupted on continental crust. Almost all records either two periods of enrichment (as opposed to the data for the Takla Group fall within the continental-arc field.

53 Chemicaldata, in conjunctionwith the overall coarse fraction. The present limited data precludes con- characteristics of theTakla Group volcanics andsedi- fident dating any closer than late Paleozoic. ments, suggests they formed in an island arc. The lenticular bodies of gabbro occurwithin phyllites and argillites of the Slate Creek succession and Big Creek INTRUSIVE ROCKS group. If their contacts are intrusive then this makes these rocks no older that Late Triassic. Thisconclusion run CARBONATITES contraryto the approximatelate Paleozoic age for the (Late Devonian to Early Mississippian) Wolf Ridge gabbro. This suggests that either the contacts are not intrusive or that the argillites assigned to the Slate Carbonatite and syenite intrude the lngenika Group at Creek succession are older. This latter inference is quite Granite Creek andapproximately 5 kilometres northeast of possible considering the abundance of similar, variously the Wolverine Lakes. These bodies are small; the Granite aged argillite packages in the map area. The mafic com- Creek exposure is only 50 metres wide and 500 metres position of these bodies and their proximity to the Manson long. They contain significant concentrations of rare earth Lakes ultramafics and associated rocks of the Nina Creek elements, particularly niobium. They have been dated by group,suggests a genetic relationship. The Wolf Ridge Pel1 (1987), using uranium/lead ratios, as Late Devonian gabbro, together with the Manson Lakes ultramafics and toearly Mississippian. For a moredetailed account of the Nina Creek group, may represent fragments of a dis- these rocks see chapter on Economic Geology and Pel1 membered ophiolite. The Crooked amphibolite, which is (1987). correlative with the Manson Lakes ultramafics, contains gabbroic lithologies (Rees, 1987)which further suggests a WOLF RIDGE GABBRO linkbetween the Wolf Ridge gabbro and theManson (Informal, Lute Paleozoic to Earliest Mesozoic?) Lakes ultramafics. The present data do not permit resolution of this problem. Lenticular bodies of gabbro, the largest of which is some 15 kilometres long and 3 kilometres wide, are found within the Manson fault zone. They extend, en echelon, WEHRLITE fromimmediately southeast of GermansenLanding to (Triassic to Jarassic) southeast of Lower Manson Lake. The best exposures are In the northwest panof the maparea. the basal pan of on Wolf Ridge, directly north of Manson Creek. the Pillow Ridge succession contains lenticular bodies of The margins of these bodies are not well exposed. wehrlite up to 200 metres thick. These occur at several Typically, highly strained or brittly deformed rocks occur horizons and areassociated with gabbro sills and siliceous close to gabbro contacts, as near the Fairview showing, I sediments of the Pillow Ridge and Mount Howell succes- kilometre northwest of Manson Creek, and on the north sions. They are composed of clinopyroxene, olivine, ser- shore of Lower Manson Lake. On Wolf Ridge, there is a pentine (after olivine) and magnetite. The contacts with decrease in grainsize toward theedge of the gabbro thesurrounding rocks are not tectonically disturbed, (towardsthe southwest) whichmay represent a chilled indicating they are intrusive. margin.However, the lenticu!ar shape of these bodies, This groupof intrusions may be related to the Polaris their presence within the Manson fault zone, and the fault Complexand related Alaskan-type ultramafic bodies zones near their margins, all suggest that their contacts are which intrude rocks of similar age in the Uslika Lake area probably faulted and that the gabbros preserved along the and in the Lay Range (Nixon et al., 1990; Roots, 1954). Manson fault are slivers of an originally larger intrusive body. GABBRO (Jurassic or Younger) The gabbro is green to dark greenand light brown to A small body of gabbro intrudes the lower part of the rusty brown weathering. It ranges in composition from 40 Takla Group, I kilometresouth of themouth of Nina to60% completely sericitized plagioclase with the Creek. It is grey, massive, medium to coarsely crystalline remainder of the rock being pyroxene, minor hornblende andcontains a very weak foliation whichtrends nortl- and biotite. It is typically fine to mediumgrained, although westerly. It is composed of plagioclase (50%), pyroxene pegmatitic phases are present on the crest of Wolf Ridge. (30%), sphene(?) (10%) and hornblende, sericite and cal- Almost all exposures of this unit exhibit a weak to cite. Similar gabbro intrudes Takla rocks at the extreme moderate minerallineation with an accompanying, very western margin of the map area, immediatelynorth of the weak planar fabric. This weak fabric may grade into zones Omineca River. It does not resemble the Wolf Ridge gab- of mylonite a few metres across but the deformation is not bro and its exact age and relationship to other intrusive uniformthroughout any outcrop. The highly strained rocks is not known. zones are generally found toward the edge of the gabbro bodies. GERMANSEN BATHOLITH AND RELATED Age: PreliminaryU-Pb radiometric dating of the Wolf Ridge gabbro is ambiguous dueto: the limited num- ROCKS (Cretaceous and Tertiary) ber of zircon fractions analyzed, their low uranium and The southern part of the map area is intruded by the leadcontents, and low measured 2mPhP”Pb ratios Germansen batholith. It is exposed on the alpine slopes (Appendix 11, Figure 69). An approximate minimum age near Mount Gillis and extends northwestward to the area of 245.4 2 0.7 Ma (2u) is given by the near concordant around Mount Germansen,immediately south of Ger-

54 mansen Lake. The batholith is a multiphase intrusion com- Abundant monzonite to quartzmonzonite intrudes posed of granodiorite, two-mica granite,related pegmatitic the Germansen batholith around Mount Germansen, and phases and aplite dikes. segments of the Olsen Creekfault. These rocks form dikes Granite is characteristic of the Mount Gillis area, but up to 15 metres wide and irregular bodies over 20 metres granodiorite and diorite border phases were mapped at the in diameter. Only a few dikes were observed in the Mount southeastern contact. The granite is white to grey in colour Gillis area. This unit lacks the penetrative fabric of the and weathers beige to pink. It is commonly coarsely crys- Germansen batholith. talline and occasionally phenocrysts of potassic feldspar Extensive subvolcanic orextrusive examples of these up to a few centimetres in length are present. Accessories rocks can be seen along West Dog and Dog creeks west of are primarily biotite and muscovite with lesser amounts of Germansen Lake. Smaller extrusive centres arefound west hornblende and, in some areas, chlorite after biotite. Gran- of Lower Manson Lakes within the Boulder Creek group ite pegmatite and aplite dikes, up to a metre in thickness, and along Connaghan Creek. These volcanics(?) are quite cut the batholith. The pegmatites are similar in composi- calcareous along Dog Creek and are associated with cop- tion to theintrusion hut commonly containgarnet and per and zinc mineralization (Table 6). The wide distnbu- occasionally apatite. tion of outcrops of this type in the area west of Germansen Near Mount Germansen, the batholith is a weakly to Lakesuggests this area is entirely underlain by these moderately foliated hornblende biotite granodiorite com- rocks. posed of 40 to 50% plagioclase. 20 to 2S% quartz. 15 to Age andCorrelation: Aspecimen of subvolcanic 20% potassicfeldspar and IO to 15% biotiteand hornblende.Accessory minerals include apatite, zircon andesite from immediately east of Connaghan Creek, in and magnetite(?). It is medium to coarsely crystalline and the southern part of the map area, returned a biotite K-Ar commonly contains large (up to 5 centimetres long) phe- age of 48.6 Ma (Appendix 11). These rocks appear very similar to small porphyry bodies which intrude the Ger- nocrysts of potassic feldspar aligned along the foliation. The foliation generally parallels the intrusive contact and mansenbatholith and its margin.Monzonite from the Germansen batholith has yielded a K-AI age of 45 Ma on is a:sociated with a steep mineral lineation indicating that this fabric is related to batholith emplacement. biotite (see Appendix 11). Mineralogicallyand geo- chronologically,these two groups of rocksare similar Rocks in the southeastern parts of the intrusion are which further suggests they are genetically related. similar in composition to thegranodiorite in the Mount Germansen area but arefiner grained, lackphenocrysts Subvolcanic and volcanicrocks of thissuite near and are only weakly foliated. ConnaghanCreek were originally included with the EndakoGroup by Armstrong(1949). Armstrong also Age: Severalradiometric dateshave been obtained noted that these rocks have greater affinities with younger fromthe batholith in the studyarea. Garnett (1978) Eocene or Oligocene felsic volcanics than with the pre- obtained K-Ar ages of 106 and 86 Ma on hornblende and dominantly mafic volcanics of the Endako Group. Eocene biotiterespectively from the granodioritebelow Mount felsicvolcanism within the centralIntermontane Belt is Germansen.The 20 Ma differencebetween the cooling represented by theOotsa Lake Group (Souther,1991). age;probably reflects resetting of the biotite K-Ar sys- Monzonite and their extrusive equivalents in the map area tematics by local Tertiary monzonite intrusions as opposed are correlated with Eocene Ootsa Lake Group volcanics to !.imple cooling of themagma. This studyobtained a and related intrusive rocks K-fir date of IO7 Ma on biotite from two-mica granite in the Mount Gillis area (Appendix 11). These data suggest that both phases of the Germansen batholith were closely spa8:ed in time. MONZONITE TO SYENITE (Cretaceous or Tertiary) In thesoutheastern part of the maparea, approx- MONZONITE TO QUARTZ MONZONITE AND imately 2 kilometres east of the Manson River, bodies of RELATED VOLCANICS (Early Tertiary) monzonite,monzodiorite and syenite intrude schists and Small irregular stocks (less than 1 square kilometre) gneisses of thelngenika Group (Halleran, 1988). They and dikes of andesiteor related monzoniteor quartz form small stocks or dike-like bodies and are important in monzoniteporphyry intrude rocks of the Takla Group, that they cany significant amounts of rare earth elements Nina Creek group. Germansenbatholith and lngenika (src EconomicGeology). They contain accessory Group in thesouthern part of the map area. They are aegerine-augite which is commonly altered to epidote. loc.%llyvesicular, indicating a possibleextrusive or sub- There is no age on the rare earth rich syenites east of volcanicorigin. The dikes trend predominantlynorth- the Manson River. They lack a penetrative fabrictypical of northwest and are commonly recessive, producing gullies. theDevono-Mississippian carbonatites, suggesting they The monzonites are beige to pinkish in colour and are aremuch younger. Theserocks are found within the plagioclase.potassic feldspar and quartz phyric (quartz. Wolverine Range and are spatially related to theLate monzonites) with the quartz displaying resorbed margins. Cretaceousto Tertiary('?) Wolverine Range intrusions, Thematrix is composed of fine-grainedplagioclase, suggesting a genetic link. The abundance ofTertiary intru- potassicfeldspar and muscovite. Phenocrystsare mus- siveand volcanic activity in the area does not preclude covite, biotite and hornblende these intrusions from being younger than Cretaceous.

55 WOLVERINE RANGE INTRUSIONS (Informal, mum age of 7 I .O 2 0.6 Ma (2u)is obtained using points b Late Cretaceous to Tertiary? or Older?) and c (Figure 70). The ~“7Pbl”sU ratio provides the most dependable date for monozite analyses which in this case A series of dikes and sills of pegmatite and related is 72.820.2 Ma (2u). Theage of inherited lead is granodioritic stocks intrudes the strongly metamorphosed 1.8 2 0. I Ga based on upper intercepts through points h rocks of theIngenika Group in the Wolverine Range. and c (Figure 70). These intrusive rocks are volumetrically important as they constitute over50% of the exposedlithologies in the lower Many of thelarger pegmatite sillsand dikes com- parts of the Ingenika Group within the Wolverine Range. monly contain a poorly developed, widely spaced cleav- Pegmatite typically occurs as dikes and sills up to 5 age or foliation at their contacts which parallels the folia- metres thick and large irregular outcrops of pegmatite up tion in the metasediments. This indicates that these rocks to 250 metres in diameter are common. These bodies are mayhave intruded near the end of the D, deformation grey to white in colour and are made up of garnet, mus- which is of Jurassic age (see Structure chapter). Many of covite, biotite, quartz, potassium feldspar and plagioclase. thethinner pegmatite sills and dikes are strongly Garnet comprisesup to 10% of the rock; it is often concen- boudinaged, sometimes to the point of complete disloca- trated toward the contacts of the sill or dike. Micas con- tion. However, the large bodies of granodiorite contain a stitute up to 20% of the pegmatites and large crystals of weak, northeast-trending foliation not related to any of the mica, up to 10 centimetres across, are commonly present main deformationalevents, indicating that theymay be within some of the larger pegmatite bodies. much younger (as shownabove) than the hulk of the Granodiorite is grey to beige in colour, medium to pegmatitic material. very coarsely crystalline and occurs as small stocks up to Devilleand Struik (1990) haveshown that in the 50 square kilometres in area. Their composition is similar southern part of the Wolverine Complexfabric found to that of the pegmatite dikesand sills, with garnet beinga within post-D, granitic rocks is probably Tertiary in age very important accessory. These rocks are very uniform in and is related to extensional and strike-slip tectonics. The composition throughout the complex. North and west of age of this fabric is based on the interpreted Tertiary age of Chamberland Creek, granodiorite and pegmatite underlie these granitic rocks. Furthermore, this fabric is shown to an area of some 60 square kilometres. The granodiorites he parallel to the D, foliation in the surrounding metasedi- display a weakto moderate foliationwhich issteeply ments. These observations suggests that the fabric affect- dipping and trends northeasterly. ingpegmatites and related granodiorite within the Age: PreliminaryU-Pb data from zircon analyses Wolverine Range is entirely Tertiary and not related to the indicate a Late Cretaceous age forthe granodiorites within older D, deformation. This fabric is probablyrelated to the Wolverine Range(Appendix 11, Figure 70). Three uplift of the metamorphic complex along the Wolverine fractions were analyzed including two monozite. A mini- and related fault zones.

56 STRUCTURE

IMTRODUCTION OMINECA BELT Manystructural stylesare evident within themap The Omineca Belt contains strongly metamorphosed area.which reflects its position along the boundary andpolydeformed rocks that culminate within meta- between two major tectonostratigraphic provinces of the morphic core complexes which record an extended period Canadian Cordillera. Thenortheastern quadrant of the area of contractional deformation spanning the Jura-Cretaceous isdominated by polydeformedand strongly meta- boundary.Subsequently these rockswere uplifted and morphosedrocks of theOmineca Belt. These rocks cooled during the Late Cretaceous to Early Tertiary (Par- become less metamorphosed and deformed to the south- rish et d,1988; Carr er a/., 1987, Brown and Can. 1990). west, such that at the upper levels of this package only one As a consequence, the core complexes are flanked by less or two phases of deformation are evident. The Intermon- deformed and metamorphosed rocks representing higher tane Belt is characterized by low-grade metamorphism and structural levels. bmad, high-level structural features similar to those in the upper levels of the Omineca Belt. These twostructural and Rocks of the Cassiar, Kootenay and Slide Mountain stratigraphic province5 are separated by the dextral Man- terranesare included within theOmineca Belt. Even son fault zone, one of several, major structural elements in though they may have been formed in regions far removed thearea. Theother importantstructural feature is the from each other, the structures present within each reflect Wolverine fault zone, a brittle-ductile fault located on the theprocesses that brought them to their present welit side of the Wolverine Complex. configuration. Fourpenetrative phases of deformation (D, to D,) Rocks of the Omineca Belt withinthe study area have been identified within metamorphic rocks of the map typify the structuraland metamorphic style of thebelt. area. They have been recognized on the basis of inter- Gneiss and schist underlying the Wolverine Range were ference and crosscuttingrelationships, structural styles rapidly uplifted during the Early Tertiary, following sev- and their connection to metamorphism. eral episodes of deformation that began in mid-Jurassic time.Uplift occurredalong theeast-side-up Wolverine A chart indicating timing of major deformational and fault zone. This fault marks the boundary between poly- metamorphicevents is shown in Figure39. Structural deformedand strongly metamorphosed rocks of the elements withinthe maparea will bedescribed with Wolverine Metamorphic Complex (Domain 1, Figure 40) respectto the twotectonostratigraphic provinces (i.e., and less metamorphosed strata in the hangingwall, which Omineca and Intermontane belts) due tothe distinct struc- in this area arerepresented by the upper pans of the turd styles and deformational histories found within each Proterozoic lngenika Group, lower Paleozoic succession region. and the NinaCreek group (Domain 2). Deformation The following discussion will make reference to spe- within the Wolverine Metamorphic Complex reflects the cific deformational "events" and related structures (D,, highly ductile. deeper structural and stratigraphic level of D,, SI, s,, F1, F,, etc.). These "events" have been the orogen (i.e,;infrastructure) whereas the flanking rocks invoked solely for descriptive purposes and do not neces- represent more brittle,upper level regions (superstruc- sarily represent distinct episodes of deformation. In fact, ture). Omineca rocks of the study area have been divided some or all of them may be part of one extended period of into three large domains reflecting these differences (Fig- deformation. ure 40). This has been done primarily for ease of discus-

Early to Middle Middle to Early to Late Cretaceous - Jurossic and later (?) Late (7) Jurassic Middle Creloceous to Early Teriary

(Wolverine Monson - ___ Metamorphic Antiform) fault zones Peak Germansen Wolverine Batholith Intrusions

Figure 39. Relative timing of main deformational, metamorphic and intrusive events in the study area

57 Cretaceous to Tertiary Manson and Wolverine fault systems. Domain 3 is a narrow region which is open to the southeast and tapers to a single fault plane in the northwest where the two bounding fault strands come together. No markerhorizons are recognized within the monotonous BoulderCreek sequence, and as a result,the internal geometry is unknown. The eastern part of the Omineca Belt (Domain 1) is characterizedby the Wolverine antiform, a broad, kilometre-scale D, structure. Except for fold hinges, foliation is everywherelayer parallel. There are no marker horizons within the lower lngenika Group and so detailed megascopicstructures could not he delineated. Only upright, kilometre-scale F, folds could be mapped by the reversalof bedding attitudes. As aconsequence, the detailed internal geometry of this region is unknown. Rocks west of the Wolverine fault zone (Domain 2) define a southwest-dipping homoclinal succession representing the west flank of the Wolverine antiform. Stratain the Porter Creek area swing eastward and delineate the top of another large, subsidiary antiform. Outcropin the Porter Creekarea is verylimited and does not preclude the presence of thrust faulting as a possible mechanism for the production of this pattern. The homoclinal succession of Figure 40. Structural domains used in discussion of structural Domain is Illodified by large subsidiary in the trends. northern part of the map area and is cut by a series of late, normal faults. In Domain 1, metamorphic mineral assemblages indi- sion and to contrast the structural styles in each domain whichreflect the different metamorphic grades at each categarnet to sillimanitegrade or higher. Theserocks level. behaved quite plastically duringDl deformation leading to the production of a strong, ubiquitous layer-parallel fabric. Domain 1 is located east of the Wolverine fault zone Most of the rocks in Domain 2 are at chlorite grade or and essentially follows the trend of the Wolverine Range. lower. As a consequence these rocks were relatively less It is composed of high-grade metamorphic rocks of the ductile during Dl deformation and movement was concen- Ingenika Group. Rocks of Domain I were at considerably trated along comparatively incompetent horizons or fault higher grade (garnet to sillimanite) during the progressive zones. Only a small area of Domain 2 (on the northeast deformation and remained relatively hot until Early Teni- flank of Breeze Peak) is between biotite and garnet grade, ary time. and contains similar fabrics to those in Domain 1. Domain 2 lies between the Wolverine and Manson Thefour phases of deformationare most clearly fault zones and occupies a much broader area. Due to the developed within the strongly metamorphosed rocks in the variable attitude of the Wolverine fault zone, this domain eastern part of the belt. Only oneor two of these phases of is considerably wider at its northwestern end. In the Man- deformation are clearly evident in the western part of this son Lakes zea it is some 5 kilometres wide, whereas in region. The following discussion examines the structural the north it is over kilometres in width. This domain 20 elements of each phase of deformation. includes rocks of the Swannell to Tsaydir formations, the lower to middle Paleozoic succession and oceanic rocks ofPHASE 1 the Nina Creek group. Mostof the strataof Domain 2 were belowgarnet grade metamorphism during deformation Themost dominantstructural element of the Dl andcooled in Middle Jurassic time. It alsocontains a deformation is the ubiquitous, layer-parallel foliation (S,). series of excellent marker units (Atan Group and Espee It was produced by the preferential alignment and subse- Formation)which are useful in outliningmegascopic quent growth of phyllosilicate minerals parallel to bed- structures.Fossiliferous units within the domain permit ding. This fabric is most pronounced in rocks above the the documentation of numerous cryptic thrust faults. biotite isograd. Domain 3 lies within the Manson fault zone. Rocks Throughout most of Domain 2, this SI fabric is most of Domain 3 are dominated by the Boulder Creek group, prominentlydeveloped within interlayered siltstone and thoughtto be part of theKootenay Terrane and strat- shale or sandstoneand shale sequences with the fabric igraphically linked to rocks of the Cassia Terrane. They being most prominent within the shaly layers. Typically containpolyphase structures and metamorphic muscovite and chlorite porphyroblasts have grown parallel assemblages(garnet-staurolite) typical of Cassia rocks to compositional layering in shaly horizons. withinDomains 1 and 2. Thepresent configuration of In Domain 3 (Boulder Creek group) thefirst phase of these rocks is a consequence of movement along the Late deformation also resulted in a layer parallelfoliation (SJ Its vergence is unknown asno minor structures were obijerved. Deformation and metamorphism were contemporaneous with metamorphism,outlasting deformation (see chapter on Metamorphism). Within the strongly metamorphosed rocks of Domain I, D, structuresare characterized by tight to isoclinal, northeast-verging folds with an axial planar foliation (S,) defined by thepreferred growth of micaceous minerals (Plate 26). F, folds are relatively rare as can he seen from the relatively few measurements plotted on Figures 41 and 42. They exhibit a similar type fold style (Ramsay, 1967) which is common in rocks deformed at high temperatures. The presence of micas at a high angle to bedding within the hinge zones of F, folds indicates that compositional layering has been transposed parallel to foliation during folding. Figure 41. Equal-area projection of F, fold axes, southern part of Domain 1. These trend southeasterly for the most pan. In the northernpart of Domain I, F, fold axes, together with metamorphic mineral lineations (Figure 43). trend southeasterly. These fold axes are subhorizontal to slightly southeast plunging. Some of the fold axes plotted on Figure 41 plunge southwest or vertically. This may be thr: result of motion along the ductile segment of the Wadverine fault zone which has rotated the fold axes into the transport direction. Alternatively, these attitudes may be the result of northeast transport during compressional deformation. Mesoscopic F, folds are very rare in most of Domain 2 and may simply reflect the lower ductility of these rocks. In the Big Creek group, tight, northeast-verging chevron folds were mapped near the Otter Lakes (Plate 27). Their t axialplanes are subparallel with compositionallayering and their fold axes trend northwesterly. Similar folds were m.lpped in carbonate rocks of the upper Big Creek group. One outcrop of quartz-chert wacke in the Big Creek groupcontains a very stronglineation produced by stretched quartz and chert clasts. It plunges gently IO the northwest, appears parallel to bedding and is believed to Figure 42. Equal-area projection of F, fold axes in the be related to this phase of deformation. northern pan of Domain 1.

Plate 26. F, fold in schists of the lower Swannell Formation north N=18 of Edmunds Creek. These folds are very difficult to distinguish w:thin the rather monotonous clastic sequence of the Swannell Formation. They commonly display a similar fold style and are Figure 43. Equal-area projection of mineral lineations in the tight to isoclinal. northern pari of Domain 1

59 Small, 1 to 2-centimetrewavelength, northeast- verging folds were observed in thinly layered carbonates of theAtan and Echo Lake groups. Similar fold styles outlined by quartziticlayers of the Atan Group, have been noted in a float boulder. A crenulated SI foliation was observed in the hinge regions of mesoscopic folds in Domain 1 and in the high- gradeareas of Domain 2 (Plate 28). Thesefolds are northeast-verging, tight to isoclinal and have axial planes parallel to compositional layering and SI foliation. They are extremely rare in the map area and, we believe, do not warrant a separate classification. They clearlypostdate metamorphism as evidenced by the lack of mica growth in their hinges; yet thesefolds have the same vergence, morphology and attitude as F, folds. It seems possible that late in D, deformation, SI foliation was refolded in discrete areas due to local perturbations in the flow regime. The age of Dl deformation must he Middle Jurassic. Thisis deduced from cooling K-AI ages of syn- metamorphicminerals in the hangingwall of the Wolverine faultzone which are dated at 171 Ma (see chapter on Metamorphism). Rocks in the footwall of the Wolverine fault zone (Domain I) either remained hot until the Early Tertiary or were reheated in the Early Tertiary. Plate 27. Tight chevron fold in Big Creek shales (immediately to The latter interpretation assumes that the primary fabric the left of the pencil), near Otter Lakes. These northeast-verging folds may be related to D, deformation. seen in the Wolverine Range was producedduring Dl deformation and that it is the same as the Dl fabric in the hangingwall of the Wolverine fault zone. It is only along the Wolverine fault zone that earlier D, foliation is overprinted by fabricproduced during motion on the fault zone.

PHASE 2 In the monotonous, metamorphosed sequence of the SwannellFormation, compositional layering, together with the S, fabric, are folded into kilometre-scale, upright folds which we believe to be F, structures. These megascopic folds have been delineated primarily by dip reversals on the earlier planar elements. The folds are associated with similarly oriented and commonly observed fold crenulations whichhave a wavelength of 1 to 2 centimetres. In the southern part of Domain I, in areas above thesillimanite isogrdd,subsidiary megascopic F, folds were not observed and only rarely were F2 crenulations noted. These folds are most dominant above the garnet isograd (in Domain 2) and may indicate a depth depen- dencyfor D, deformation.The simplest interpretation based on structural data suggests that F, folds are related to the Wolverine antiform due to their post-peakmeta- morphicnature and similar orientations.However, mica growth parallel to S, cleavage planes in the Boulder Creek group, indicates that these kilometre-scale folds may he older than the antiform as this anticlinorium folds metamorphic isogradsof the region. This mica growth suggests that D, deformationoccurred near theend of regional Plate 28. Flat-lying late-F, foldnear the mouth of Edmunds metamorphism. In the Ingenika Range these arepost-peak Creek. S, foliation is axial planar to thesefalds, but as seen here, metamorphic structures which are clearly older than the this foliation is crenulated within these fold hinges suggesting Swannell antiform (a structure equivalent theto Wolverine these folds are late in D, deformation. See text for details. antiform; Bellefontaine, 1990). The attitude of the crenulations in the northern pari of Domain I is illustrated in Figure 44. Note the vertical to steep northeast dip of the axial planes indicating that F, folds, if axial planar to these crenulations, are inclined to the southwest. In the northern part of the map area, the few crenulation fold axes observed within homogenous layers are subhorizontal. The region occupied by Domain 2 contains a series of excellent markers which delineate several megascopic D, folds within the southwest-dipping panel of strata. These folds are upright to slightly inclined to the northeast (Fig- ure 45). Cross-sections (Figure 7) indicate that these structures are probably northeast verging. N=9 Megascopic folds are most prominent in the northern part of thisdomain. NearMount Howell,the Mount Howell successionoutlines several broad, southwest- Figure 44 Equal-area projection of poles to F, crenulation planes. nonhern pans of Domain I plungingfolds with wavelengths in the order of 5 kilo- meyres. This succession also outlines a very wide, faulted syncline nearBlue Grouse Mountain. Segments of this structure have been rotated by the northeast-trending faults such that its plunge is in the order of 30" to the southeast (Figure 46). The basal beds of the Mount Brown quartzite outline an open, upright and north-west plunging fold pair below Mount Brown (Figure 47) which becomes much narrower to the southeast where it is outlined by the Espee Forma- tion. TheEspee Formation delineates a series of tight folds in the Mount Dewar areaand traces a broad anticline in the Granite Creek area. The wavelengths of megascopic folds in the northern par1 of Domain 2 become shoner with stratigraphic (and structural)depth. Typically foldsoutlined by the Nina Creek group are up to IO kilometres in wavelength. This decreavs to a few kilomrtres in the Atan Group and less than a kilometre in the Espee F(~rmation. Thismay he the result of the increase in ductility of these rocks with depth. Figure 45. Equal-areaprojection of polesto Sz cleavage in Macrmcopic folds were only rarely observed in rocks nonhern pan of Domain 2 showing the steep southwest dip of of .Domain 2. Oneexample is fromthe Mount Kison this cleavage set. liml:stonc south of HcnschelCreek where 100-metre wavelength, northeast-verging. similar-style folds can he seen.Chevron Told\ were occasionallyohserved in rih- honed chert or siliceousargillite sequences of the Nina Cre':k group. They are tight IO open with wavelengths in the order of I to 2 melrrh. In the northrrn pan of Domain 2, hedding-cleavage intersection lineations (Figure 48) consistently indicate a gentle northwest plunge for large stmctures. This changes to ;I southeastplunge toward the southern pan of the donrain (Figure 46)...... On a micr~rscopicscale. DL is expressed as a penetre- rive. slaty to crenulation cleavage. Crenulations are common in regions above biotite grade metamorphism where micaceousminerals have produced a strong anisotropy. The character of these crenulations was described in an earlier section. N=36 InDomain 3 second-phasecrenulations are only found in a few localities,near Skeleton Mountain and Figure 46. Equal-area projection of poles to bedding within the south of Boulder Lake. They have a wavelength of 0.5 to I MountHowell succession, nearBlue Grouse Mountain, Do- centimetre and generally do not exhibit pressure solution main 2.

61 cleavageplanes are deflected by theporphyroblasts, indicating that this deformation is postmetamorphic. The S, cleavage generally dips to the southwest (Fig- ure 43, hut in the northern part of Domain 2, near Mount Brown, cleavage dips steeply to the northeast. The anomalous attitude may result from cleavage fanning along the northeastlimb of the fold pair below Mount Brown. Cleavage refraction is sometimes observed in interlayered slate-siltstone sequences in the upper Ingenika Group or lower Atan Group. In Domain 3 bedding and the early S, foliation are folded into a broad, subhorizontal anticline attributed to D,. Its vergence is unknown. Theage of D, deformation is bracketedbetween Figure 47. Equal-area projectionof poles to bedding within a fold Middle Jurassic and Cretaceous. This corresponds to post- pairdelineated by the Mount Brown quartzite, nearMount D, deformation and the onset of D, anticlinoria (Even- Brown, northwestern end of Domain 2. This diagram shows the chick, 1988). Growth of metamorphic micas parallel to S, gentle northwest plunge of these structures cleavage planes within the Boulder Creek group indicates that this deformation began in Middle Jurassic time. This deformation appears to postdate metamorphism elsewhere in the study area, suggesting thatD, deformation outlasted metamorphism. This argument assumes that the S, cleavage seen in the various domainsof the map sheet areof the same age.

PHASE 3 + This is the most prominent phase of deformation in the Omineca Belt. It is represented by the broad, north to northwest-trending Wolverine antiform which dominates Domain 1. Thislarge fold is oneof many anticlinoria within metamorphic rocks of the northern Omineca Belt (Gabrielse, 1975). Plots of foliation along its length (Fig- ures 49, 50 and 51) indicate the curving nature of its fold J crest. In the Manson River area (Figure 49), this antiform Figure 48. Equal-area projection of bedding-cleavage intenec- plungesnorthwestward whereas in theBison Mountain tionlineations within Proterozoic andPaleozoic sediments, area (Figure 50) the plunge is to the southeast. Near the northwesternpart of Domain 2. Thenonhwest plunge is in Osilinka River (Figure 51) the structure is subhorizontal. agreement with data in Figure 47. In the northwest, the core of the antiform has been cut by the Wolverine fault zone alongthe Osilinka River. Its trace is lost north of the river. on the limbs. They postdate peak metamorphism (as seen by their deflection around staurolite porphyroblasts, see also chapter on Metamorphism) hut biotite porphyroblasts have grown parallel to the crenulations.It appears that the timing relationships between deformation and metamorphism in Domain 3 areslightly different from those in Domains 1 and 2. Elsewhere, in rocks below the biotite isograd, S, is typically a pressure-solution cleavage which may be associated with a crenulation in shaly rocks that have a strong S, fabric. In silty rocks the cleavage is manifest as pres- suresolution and micaceous seams around clasts. A spacedpressore-solution cleavage is commonlyfound within the calcareous units of this subdomain. The presence and spacing of the cleavage reflect the argillaceous content of the carbonate. The ragged morphologyof phyllosilicates on cleavage planes indicates that they have been rotated during dissolution of the enclosing rock. No phy- Figure 49. Equal-area projection of poles to compositional layering, southeastern part of Wolverine antiform, Domain 1. These llosilicateshave grown along these cleavage planes. points delineate a very poor girdle with its pole plunging gently Where porphyrohlasts, such as chloritoid, are present the to the northeast.

62 The age of this structure, and others like it, is most likely Earlyto Middle Cretaceous. Evenchick (1988). notes that in the northern Cordillera, anticlinoria like the Sifton and Swannell antiforms, have significantly younger K-Ar metamorphic cooling ages intheir cores than on their limbs. These ages range from 90 to 140 Ma. Even- chicksuggests thatthese variable ages reflectgradual uplift and cooling of these rocks during the production of these large D, stmctures.

PHASE 4(?) A fourth phase of deformation is postulated for this area. It is expressed by the presence of a weak, steeply dipping,northeast-trending foliation in thegranodioritic bodies that intrude highly metamorphosedrocks in the Figure 50. Equal-area projection of poles to compositional layer- Wolverine Range. The attitudeof this foliation (Figure 52) ing nlong the Wolverine antiform. Mount Bison area. Domain I is unrelated to any other structures except rarely observed These points define a girdle with its pole plunging to the south- crenulations in metasedimentaryrocks of the complex. east in conjunction with F, foldaxes and mineral lineations. D, deformation is found within Late Cretaceous or possiblyEarly Tertiary granitic bodies (see chapteron Lithologic Units). This implies that it is Late Cretaceous or younger.

FAULTS Faulting is only observed within the superstructure where excellent markerhorizons arepresent. Thrust faults, in highly monotonous sequences are demonstrated mainly on thebasis of agereversals apparent from fossil data. THRUST FAULTS Significant thrust faults are present within, and at the base of, the Nina Creek group. They are layer parallel and are mapped primarily on the basis of conodont age determinations. These fossil data indicate the presence of thrust faults between the Pillow Ridge and Mount Howell suc- Figure 51. Equal-area projection of poles to compositional layer- cessions, and the Mount Howell succession and Big Creek ing, northwestern part of Wolverine antiform, Domain 1. These group. Thrust repetition of the Mount Howell and Pillow pints clearly display the subhorizontal attitude of D, structures Ridgesuccessions is alsodemonstrated in the north- (Wolverine antiform fold axis). western part of the map area. There is little or no observed evidence (such as shear zones) for the existence of these thrust faults. These faults also suggest that the monotonous sequences of the Mount Howell and Pillow Ridge successions containnumerous thrust faults which could not be delineatedgiven the sparse fossil data available. Numerousthrust imbrications have been demonstrated within Slide Mountainrocks elsewherealong theCor- dillera (Gordey, 1983: Struik and Orchard, 1985: Harms, 1985a. b, 1986; Klepackiand Wheeler, 1985;Schiarizza and Preto, 1987; Nelson and Bradford, 1993). Interleaving of the Mount Howell and Pillow Ridge lithologies is evident north of Pillow Ridge. Mapping to thewest and northwest by Ferri et a/. (1992a, bj and Nelson et a/.(1993a, b)clearly demonstrated the emplacement of awedge of Mount Howellsediments between Pillow Ridge basalts. The fault panel of Mount Howell rockspinches out southwestward into the present map area, with the two bounding faults apparently joining and Figure 52. Equal-area projection of poles to S, cleavage in following the GoatCreek valley. A similar thrustfault granodiorites of the Wolverine Range. repeatsMount Howell and Pillow Ridge rocks imme-

63 diately to the northeast. The stratigraphic level at which kilometres upstream from its mouth, strongly altered ultra- this fault occurs varies along its trace, as indicated by the mafite is in fault contact with metasediments of the Boul- uneven distribution of Mount Howell sediments. der Creek group. The fault zone is flat lying to slightly Fossil data indicate a thrust fault of unknown dis- southwestdipping and strongly sheared (Plate 29). placement between Nina Creek rocks and those of North Kinematicindicators are consistent with a top-to-the- American affinity. This structural relationship between the northeastemplacement of theultramafite. Contact rela- Cassiar and Slide Mountain terranes is the same as docu- tionships seen at this locality suggest that the other ultra- mentednorth and south of thestudy area (Nelson and mafite bodies immediately to the north and northwest are Bradford, 1993; Struik and Orchard, 1985; Schiarizza and also boundedby flat-lying thrust(?) faults and that they are Preto,1987; Rees, 1987; Struik, 1980; Harms, 1986; pan of an imbricate thrust package including the enclosing Klepacki1983). metasediments.The emplacement of theseultramafite bodies is believed to have occurred in the Middle Jurassic. Thesethrust faults are most likely east verging as This is based on correlationof these ultramafites with the thereis no eastern source for rocks of the Nina Creek Nina Creek group. groupin the miogeocline. There is clear evidence that The southwest margin of the Boulder Creek group these rocks represent obducted pieces of an ocean floor (Domain 3) is interpreted as a splay of the Manson fault thatformed west of the continental margin (Monger, zone, based on its subparallelism with the fault zone and 1984). thepresence of numerous ultramafite bodies along its Ageconstraints for these thrust faults can only be trace. Ultramafite bodies are an important characteristic of broadly defined. They are post-Permian but must predate theManson fault zone inthe maparea. Due to poor D, deformation which is believed to be Cretaceous in age. exposure, actual contact relationships between the ultra- The only other major deformational eventin the Omineca mafite bodies and surrounding rocksof the Boulder Creek Belt of this magnitude and with the same sense of ver- groupand Slate Creek succession were notseen. Sur- genceis D, deformation. Itis suggestedhere that the rounding rocks provide no indication of major shearing thrust emplacement of the Nina Creek group is part of Dl related to thrust emplacement as occurs in theBoulder deformation and is Middle Jurassic in age. Creek area or as described in similar rocks farther south Bodies of ultramafite occur within Domain3 north of (Rees, 1987. Struik, 1985). This lack of evidence does not BoulderCreek. Along Boulder Creek, approximately 2 preclude the possibility that an obscure thrust relationship

Plate 29. Flat-lying thNSt fault between Manson Lakes ultramafics (above) and Boulder Creek sediments (below) as exposed along the nolth side of Boulder Creek. Kinematic indicators suggest eastward motion of the Manson Lakes ultramafics.

64 may be somewhere preserved.Alternatively, an original Henschel, Blue Grouse Mountain. Nina Creek and Echo thrust relationship between these rock units may havebeen Creek fault systems. The Henschel fault is a northwest- overprinted by later fault motion along the Manson fault side-downstructure and is the largest of these, with a zone. displacement upwards of 2.5 kilometres. It has been traced Demonstrablethrust faulting israre within the fromnortheast of Echo Lake, southwestward to 3 Mile remaining parts of the Omineca Belt. Just south of Granite Creek (Figures 7 and X) where it is cut by the Manson fault Creek, a repetition of the Espee Formation is interpreted as zone. This fault involves rocks of the Nina Creek group, athrust fault. This interpretation is different from the lower Paleozoic succession and the lngenika Group. The offset anticline proposed by Ferri et al. (1988). large syncline outlined by the Mount Howell succession in the Blue Grouse Mountain area, is lost north of Henschel A thrust fault is interpreted to repeat Razorback and fault. Blue Grouse Mountain fault cuts this large syncline Echo Lakestrata in thenorthern part of the map area. and has rotated segments of it to the southeast. Shales and argillites along the Osilinka River, to the north, containOrdovician graptolitesand may bepart of the Northwest of Nina Creek, packages of siliceous sedi- Razorback group (Ferri el a/.. 1993a, h). This thrust fault ments occur within the hasalts of the Pillow Ridge succes- w~~uldhelp explain the increased thickness of the Echo sion. These sediments do not continue along strike to the Lake group in the northern part of the map area. Its age is southeast, indicating a faultalong this valley. Similar argu- uncertain but it is most likely related to either D, or D, mentsindicate the presence of afault along the Nina deformation. Alternatively, these shales may be part of the Lake-Echo Creek valley. Northwest of Nina Lake, a suc- Echo Lakegroup (see Razorbackgroup) in which case cession of siliceous sediments disappears abruptly south- there would be no need to invoke this thrust fault. east of the valley, and, in conjunction with displacement on the lower Pillow Ridge contact, indicates a southeast- side-down fault. The valley containing this fault is a con- NORMAL FAULTS spicuous,straight, northeast-trending feature essentially Two sets of normal faults affect the superstructure in parallel to the Henschel fault. the study area, one trending northeast and the other north- NearEcho Creek, a series of normal faultsforms west.Northwest-trending normal faults are concentrated severalsmall graben-like structures.These faults are in the northwest portion of Domain 2, where they cut the prominent on the ridge northwest of Mount Kison where upper parts of the lngenika Group, the lower Paleozoic they offset the basal beds of the Mount Brown quartzite. sequence and lower parts of the Nina Creek group (Figure They have been projected to the southwest to explain the 7). The most significant of these faults have been named outcrop pattern of limestone and shale in the upper part of (from northeast to south) Flegel Creek, Big Creek, Razor- the Paleozoic succession. back Mountain and Mount Forrest. All, except the last, are Northeast-trending normal faults appear to he region- noltheast-side-up normal faults. Their traces indicate that ally important.Straight, northeast-trending valleys are they dip steeplysouthwest. Maximum displacement on present throughout the Omineca and Intermontane belts any one of these faults is in the order of 2 kilometres. northwest of the study area (Wasi and Uslika lakes). Northeast-side-up normal faultsare parallel to the The inferred age of fault motion is based on their trace of the Wolverine fault zone along the OsilinkaRiver. crosscutting relationships with other fault systems. They The similar orientation and sense of displacement of the cut thrust faults within the Nina Creek group, indicating two fault systems suggest they are genetically related. The they are post Early to MiddleJurassic. They are apparently concentration of these faults withinrocks of the upper CUI by the MdnSOn fault Lone which would fix an upper lngenika Group and Paleozoic units may simply reflect the age limit of Late Cretaceous to Early Tertiary. Alter- presence of useful marker horizons at these levels which nativelythese faults may be contemporaneous with the allows the delineation of these normal faults. Some faults Manson fault zone (see under on MansonFault Zone). ma,y continue much further into the Swannell Formation but due to the monotonous nature of theserocks, fault displacements are not readilyapparent. These faultsare WOLVERINE FAULT ZONE probably a result of Tertiary extension and uplift of the The Wolverine fault zone separates the two principal Wolverine Metamorphic Complex. domains of the Omineca Belt in the map area. Armstrong Immediatelysouth of GraniteCreek. a northwest- (1949) first postulated the presence of this fault to explain trending northeast-side-up normal fault places the middle the discordance of strata on eitherside of it. It also pan of the Nina Creek group against rocks of the Stelkuz explains the changes in structural trends and metamorphic Formation. Thus, its stratigraphic disphcement is in the gradeacross it. Its trace marksthe boundarybetween order of 3.5 kilometres. This fault terminates to the west metamorphic rocks with early Tertiary K-Ar ages east of against the Manson fault zone and to the east against the the fault and those with older ages west of the fault. It is a Wolverinefault z,one. It is believedto he part of the brittle,moderate(?) to steep, northeast-side-up normal Wolverine fault system which places higher level Domain fault (Plate 30). It cuts. or is parallel to, a ductile shear 2 rocks against uplifted. high-grade metamorphic rocks of zone along most of its trace and the two are believed to be Dornain I. genetically related. Northeast-trending faults have been recognized in the The Wolverine fault can be traced from the Munro northern part of the map area. The most important are the Creekarea northwestward to Granite Creek, where it

65 Plate 30. Photomicrograph of fault breccia within the Wolverine Plate 31. Photomicrograph of quartz ribbons and fish-scale micas fault zone on the south side of Munro Creek. This brittle defor- within a ductile portion of the Wolverine fault zone.These mation overprints a ductile fabric found in the footwall of the strained quam and mica grains are in sharp contrast to annealed fault zone. textures within the core of the Wolverine Metamorphic Complex (see Plate 41). splays into several smaller, westerly trending faults. The A layer-parallel,southwest-dipping ductile shear mainfault can be tracedpast Granite Creek, where it zoneis found in thefootwall of thesouthwest-dipping swings to a more northerly trend and follows the foot of Wolverine fault zone in the southern part of the map area. the steep western face of the Wolverine Range. It leaves Indications of its presence were first noted by Ferri and the map area north of the Wolverine Lakes and reappears Melville (1988a) who remarked that the west flank of the east of Porter Creek.We interpret it to be composed of two metamorphicbelt contained a layer-parallel, post- faults at this point (Figure 7). The fault zone cannot he metamorphic fabric not seen in the core of the complex. traced across the Osilinka River and we believe it veers Thisshear zone can he up to 1 kilometrewide. It is westward along the Osilinka valley. typically manifested by flattened quartz grains in moder- A fault along the Osilinka River can he inferred from ately deformed areas to highly strained, ribboned quartz the juxtaposition of higher grade and lower grade meta- and kinked and fish-scale textured micas (Plate31). Linea- morphic rocks on either side of it. Across the river, north tions produced by deformed grains and elongate minerals of Dwyer Creek, the metamorphic grade increases sharply in this zone plunge moderately to the south or southwest from biotite to gamet. The traceand relative motionof the (Figure 53). althoughother mineral lineations, such as inferred fault are parallel to northeast-trending faults to thesillimanite in the Munro Creek area, plunge gently to the southwest and with a fault mappedby Roots (1954) in the northwest. Several oriented samples were collected from western part of the Fort Grahame sheet. the shear zone near the month of Ciarelli Creek. One of theseclearly indicates southwest-side-down motion The Wolverine fault zone is assumed to dip steeplyto (Plate 32). the southwest and may be parallel to a related, moderately dipping, ductile shear in its footwall. This ductile shear zone is most likely a deeper level manifestation of the brittle Wolverine fault zone. This is Displacement on this fault is variable along its trace. based on their proximity to each other and on the similar In the Munro Creek area, sillimanite-grade paragneissesof sense motion. It is assumed here that uplift along this theIngenika Group are incontact with chlorite-grade of fault zone has exposed its deeper, more ductile portions rocks of the Nina Creek group, indicating displacementof andjuxtaposed these against higher level, more brittle tens of kilometres.In the Granite Creek area, the relatively short distance between the biotite and sillimanite isograds segments of the fault zone. (approximately 2 kilometres) is artifact of displacement an AGE AND TECTONIC IMPLICATIONS on the Wolverine fault zone. In the northern part of the map area, near the Osilinka River, the fault zone is within The Wolverine fault zone separates high-grade meta- rocks of the Swannell Formation and displacement has morphic rocks of the lower lngenika Group (Wolverine decreased substantially. Just south of the Osilinka River Metamorphic Complex) from less metamorphosed rocks thefault is located within a broad, straight, north to of the upper Ingenika Group, lower Paleozoic succession northeast-trending, valley. Here rocks on either sideof the and Nina Creek group.It also marksthe boundary between fault are of similar metamorphic grade but differ in meta- metamorphic rocks with consistent Early Tertiary metamorphic cooling ages. The position of the faultis based on morphicages and metamorphic rocks dated as old as the change in metamorphic ages across it. Middle Jurassic.

66 The rheological nature of the fault zone was depth dependent. In the higher level, cooler parts of the crust, uplift was facilitated by movement on steep, brittle faults whereas in deeper, ductile regions movement was concentrated along moderately dipping ductile shear zones. These preliminary data arein agreement with detailed studies of core complexes in the southern Canadian Cor- dillera (Carr et a/., 1987: Brown and Carr, 1990). Even- chick (1988). working north of the study area in the Sifton Ranges,clearly demonstrates thatuplift ofthe meta- ' .* morphic rocks is the result of northward thrusting related .. to strike-slip motion. This possibility cannot be ruled out N=16 in the study area. A southeast extension of the Wolverine fault zone appears tofeed intothe McLeodLake - L northernRocky Mountain Trench right-lateral fault sys- Figure 53. Equal-area projection of mineral lineations in the tems. Dip-slip motion on the Wolverine fault zone, in the southern pan of the Wolverine fault zone. study area, may somehow he related to strike-slip motion farther south.

DISCUSSION The deformational history of the map area is, for the most part, consistent with that reported by other workers throughout the Omineca Belt. It begins with east-verging, synrnetamorphic D, structures and ends with the formation of postmetamorphicanticlinoria and subsequent uplift. Perhaps the most striking structural observation is the apparent lack of southwest-verging structures which have been reported by many workers to the north (Belle- fontaine. 1989,1990; Gabrielse, 1971,1972, 1975; Gabrielse er al., 1991; Mansy, 1972,1974; Mansy and Dodds, 1976) and to thesouth (Murphy, 1987; Struik, 1988a; Rees, 1987). Southwest-verging structures in the ingenika Range (Bellefontaine, 1990) have been explained using a model of tectonic wedging and delamination originally proposed Plate 32. Shear-bands within ductile portion of theWolverine by Price (1986). In this process a panel of rock is thrust fault zone, nonhof Ciarelli Creek. This is a view to the southeast eastward and wedged below a roughly correlative panel and the shear hands indicate tops-to-the-southwestmotion for the (Figure 54). The wedge is hounded above and below by upper plate. thrust faults. Theoverlying panel is transported to the southwest, relative to the wedge, along a northeast-dipping detachment at the top of the wedge. As a consequence, the upper panel is characterized by southwest-verging SING- Metamorphic ages in the Wolverine Metamorphic lures whereas structural elements in the wedge are domi- Complexindicate that these rocks were upliftedand nated by northeastvergence. The vergence reversal is cooled in earliestTertiary times. ThisTeniary uplift is accentuated if the zone of detachment between the upper further substantiated by clasts of gneiss and schist in the panel and the wedge behaves ductily before faulting. Fur- nearby Tertiary Sifton Formation (Roots, 1954, Gabrielse, thermore,early northeast-verging elements in the upper 19'75) indicatingthat the Wolverine Complex was panelare overprinted by southwest-vergingstructures unroofed in early Teniary time.Isotopic and structural whereas in the lower panel no overprinting relationship is data indicate that the uplift and unroofing of the complex seen. This model may explain structures observed in and occurred along the Wolverine fault zone. around the study area. Cross-sections of Roots (1954). just Most mineral lineations within the fault zone, dip to to the northwest, show southwesterly directed thrust faults the southwest indicating dip-slip motion. This is based on that separate regions of definite southwest-verging struc- theassumption that most of the mineral lineationsand tures from those that appear upright to northeast verging. deformed crystal grnins represent the long axisof the finite These thrusts may representthe upper detachmentfault strain ellipse which is parallel to the transport direction. It abovean underthrustwedge. Thesecross-sections also should be pointed out that not all mineral lineations indi- show areas with upright to northeast-vergingstructures. cate dip-slip movements; some aresubhorizontal and trend Similarstructures were mapped by Gabrielse (1975) northwesterly,which suggests a componentof sub- immediately east of the Aiken Lake map sheet. Two of horizontal motion. Gabrielse'scross-sections, which join alongstrike (sec-

67 based on bedding reversals as extensive marker horizons arelacking. Wavelengths of theseupright, northwest- trending folds vary from 1 kilometre to over 5 kilometres. The folds are believed to be related to similarly oriented F, folds of the Omineca Belt. In some localities a northwest- trending, vertical to southwest-dipping, spaced topenetra- tive slaty cleavage is axial planar to F, megascopic folds and is believed to be genetically related. A very prominent structure is the syncline, cored by PlughatMountain augite porphyries, between Evans Creek and the OminecaRiver. It is over 10 kilometreslong and can betraced from thewestern border of the mapsheet southeastward into the Manson fault zone. Its attitude is similar to otherF, folds in the map area hut itspresence in the hangingwall of the Evans Creek thrust indicates that it Figure 54. Modified tectonic wedging model of Price (1986). In may be related to motion on the Manson fault zone. this diagram the lower block(a) forms the wedge bounded above anticlines are older than the Germansen batholith and below by detachment faults. The wedge contains eastward- F, This is furthersubstanti- verging to upright structures whereas structuresin the over-riding as they are cutby it in Domain 4. block are west verging. ated bythe lack of a penetrative, northwest-trending cleavage inthe batholith within Domain 4. Thismakes F, structures no younger than 106 Ma (Middle Cretaceous) tionsE-F and C-D), show large-scale structures with and is in accordance with estimates fromthe Omineca Belt opposite senses of vergence, northeast and southwest. in the map area. The lack of southwest-verging structures in the study area can be explained in two ways. Apparent southwest- EAST-TRENDING STRUCTURES SOUTH OF verging structures nearthe study areasuggest tectonic THE EVANS CREEK FAULT wedging and delamination as a mechanism. If this is so, Domain is characterized by the east-west trend of then the lack of southwest-directed structures in the Man- 5 structural elements which is completely discordant with son Creek area can be explained by the area's position trends other domains. Structures related to the deforma- within the indenting wedge. Alternatively, tectonic wedg- in tional events described previously are not seen here, and ing,delamination and southwest-verging structures may no overprinting relationships were observed between the not have occurred in the map area. two structuraltrends. It is believed that these structures formed during a phase of deformation unrelated to the D, INTERMONTANE BELT and D, structures in the rest of the map area. Near Mount Rocks of the IntermontaneBelt occupy the area south Germansen, structures follow the trend of the contact of of the Manson fault zone and are characterized by broad, the Germansen batholith, suggesting that they formed dur- open structures attributed tu D, deformation and move- ing emplacement of the batholith. ment along the Manson faultzone. This largeregion is The east-trending structures in the Plughat Mountain subdivided into two domains (Domains 4 and 5, Figure area are most likely a consequence of right-lateral motion 40). Domain 4 is bounded to the northeast by the Manson on the Manson fault zone. Regional strain patterns related fault zone and tothe southwest by the Evans Creek thrust to such movement would result in bulk shortening roughly fault and the South Germansen River. Domain 5 occupies parallel to compression indicated bymegascopic struc- the area south of the Evans Creek thrust and west of the tures within Domain 5 (Figure 55). South Germansen River. A penetrative fabric is uncommon in the rocks of the Exceptfor basal shalesand argillites of the Slate Takla Group. In contrast, the Germansen batholith, in the Creek succession these rockslack the strong layer-parallel vicinity of Mount Germansen, contains a weak to moder- fabric typical of rocks in the Omineca Belt. ate penetrative foliation (Plate33). The trend of this foliation follows the contactof the batholith, indicating that it PHASE 1 is related to its intrusion. This is further substantiated by the presence of a very steep (up to 80') mineral lineation A weak layer-parallel fabric (S,?) is sometimes within the plane of the foliation. developed in the lowermost shales of the SlateCreek succession and may he related to D, deformation in the Takla Group volcanics and sediments locally contain Omineca Belt. No other structures were seen that could he a weak to moderate,steeply dipping, eastto northeast- trendingfoliation in the vicinity of the Germansen attributed to this phase of deformation. batholith. Granoblastic textures of metamorphic minerals indicate that deformation ended prior to cooling of the PHASE 2 batholith. We believe this foliation isrelated to intrusion of Phase 2 deformation is characterized by megascopic, the batholith and is a result of increased ductility of coun- northwest-trending folds. Axial traces of these folds are try rocks in response to heating during intrusion.

68 r crop by strongly brecciated limestones and shales of the Slate Creek succession exposed along Plughat Creek. The Evans Creek faultmerges with the Manson fault zonein the southern part of itstrace. The attitude and motion of this fault are compatiblewith it being a splay of theManson fault. It may hethe bounding fault of a contractional duplex or positive flower structure (Wood- cock and Fischer, 1986; Sylvester, 1988). Such a structure develops fromthe wedging of a largefault lozenge at restraining bends in the fault complex (see inset Figure 55). Severalsubsidiary faults with similar motion are inferred in this area and may have emplaced Lay Range rockssouthwestward against Takla rocks.The Wendy Creek valley may mark the trace of such structure with its motion obscured by the relatively monotonous Lay Range I I 1 succession. A thrust fault, in conjunction with a normal fault,must cut theEvans Creek limestone north of the Figure 55. Diagram showing fold and fault structures related to Omineca River and wedge it between rocks of the Lay right-lateral stnke-slip motion and theirpossible counterparts Range assemblage. within the map area (modified from Sylvester, 1988; Woodcock and Fischer, 1986). The inset shows a cross-sectional view of a positive flower structure which is theorized to he controlling the THRUST FAULTS Evans Creek thrust fault.East-trending fold structures within Thrust faults were recognized in rocks of the Dolnain 4 are part of the shortening related to right-lateral motion rarely on the Manson fault zone. Intermontane Belt due to lack of adequate marker horizons. However, a thrust fault which repeats Slate Creek argillites above basal volcaniclastics of the Plughat Moun- FAULTS tain succession is tenuously interpreted in the Germansen River area. Such a pattern may also reflect facies varia- EVANS CREEK FAULT tions in the Takla Group. The ageof this fault is unknown although it is likely related to D, or D, deformation. The Evans Creek thrustfault separates Domains 4 and 5 of the Intermontane Belt in the northern part of the NORMAL FAULTS stu'dy area. This southwest-verging, steeply dipping thrust is required along this valley to explain the abrupt disap- Normalfaulting has affected the Olsen Creek area pearance of the thick Permo-Triassic carbonate south of where a northeast-trending,northwest-side-down normal Ev.m Creek. Evidence for the thrust is provided in out- fault cuts units of the Slate Creek and Plughat Mountain

Plate 33. Steep foliation within granodiorite of the Germansen batholith, several kilometres north of Germansen Mountain.

69 successions (Meade, 1977). It is intruded by small bodies small ultramafite bodies are in vertical fault contact with of quartz monzonite at various points (Figure 7) and its deformed slates of the Slate Creek succession (Plate 36). trend and attitude suggest formation during emplacement Fault-bounded ultramafite bodies are also exposed along of the Germansen batholith. theGermansen River. Foldedand deformed Big Creek Normal faults probably separate unit 4 of the Takla argillites and tuffs, lyingwithin the faultzone, are exposed Group fromother Takla unitsnorthwest of Plughat Moun- in the old placer pits southof Germansen Landing. Atthis tain. The relative motion on these faults is not known as locality, rip-up clasts are stretched parallel to the trace of the stratigraphic relationship of unit 4 to other Takla units the fault. Alteredand fractured Lay Range assemblage is not understood. rocks crop out along the road leading to Nina Lake. Only a few lineation measurements were made along MANSON FAULT ZONE the fault zone and these consistently indicate southwest- trending, subhorizontal motion (Figure 56). An exception The Manson fault zone is the most significant struc- are lineations within bodies of Wolf Ridge gabbro which tural feature in the map area. This structural break sepa- generally plunge gently south. Depending upon the com- rates rocks of the Quesnel Terrane from those of the Slide position of the rocks involved,both ductileand brittle Mountain and Cassiarterranes. It is a vertical, transcurrent fault on which the most recent fabrics (e.g., slickensides, deformed clasts, Figure 56) indicate strike-slip displacement. Right-lateral sense of motion is given by slickensides along several segments of the fault zone. This zone was first named by Armstrong (1949) who noted its relationship to gold occurrencesin the region. It can be traced from Gaffney Creek in the southwest part of the map area, northwestward along the Manson Lakes drainage system, along the Germansen River,and into the NinaCreek valley. The faultzone is made up of a series of anastomos- ingfaults extending over awidth of 1 to 5 kilometres. The Manson fault is exposed along the main road on the west sideof Gaffney Creek wherefractured and altered rocks of the Nina Creek group cropout over a distance of approximately 1 kilometre. Strongly altered and fractured ultramafite bodies, in vertical fault contact with crumpled slates of the SlateCreek succession are exposed along LowerManson Lake. Contacts of Wolf Ridge gabbro Plate 34. Brecciated rocks within the Manson fault zone exposed bodies along the north shore of Lower Manson Lake are along the road along the north end of Lower Manson Lake. This faultedand these fault zones containstrongly fractured section contains lenses of Wolf Ridge gabbro, listwanites and and altered slivers of gabbro, ultramafite and slate (Plate serpentine of the Manson Lakes ultramafics and Big Creek or 34). Outcrops on asmall island in the centre of Lower Slate Creek argillites. Manson Lake expose faultbreccia containing subhorizontal, elongate clasts of Boulder Creek lithologies stretched parallel to the fault trace (Plate 35). Near Manson Creek,

Plate 35. Fault breccia of Boulder Creek group within the Man- Figure 56. Equal-area projection of mineral lineations, deformed son fault zone on a small island in the middle of Lower Manson clasts and slickensides along the Manson fault zone. Note the Lake.Many of these clastsare elongated subhorizontally and subhorizontal attitude. parallel to the trace of the fault zone.

70 processeshave accommodated motion onthe Manson tion of the ultramafite probably reflects movement on the fault zone. fault zone, but does not rule out alteration related to an Ultramafite bodies commonly occur as slivers within earlier compressional event. the fault zone.Ultramafite contacts within the zone are An upper limit on the age of faulting can be postu- steep and strongly fractured. The presence of these bodies lated from crosscutting relationships in the Boulder Creek was used to delineatethe zone.They typically have a area. Here, the southwestern margin of the Boulder Creek lineartrend and occur at contacts betweencontrasting block is thought to be bounded by a splay of the Manson lithologies (for example, the southwestern margin of the faultzone. The IO7 Ma(K-Ar, biotite) Germansen BolJlder Creek group). batholithintrudes the splay in the Boulder Creek area. The southwestern margin of the Boulder Creek group Thisplaces an upperage limit on the splay, and by is interpreted tobe a splay of theManson fault zone. inference, on the main pan of the Manson fault zone. Supporting evidence includes: ultramafite pods along this Regional-scale deformation resulted from movement contact, and apparent truncation of metamorphic isograds on transcurrent faults in the northern part of the Cordillera at this boundary (see chapter on Metamorphism). betweenMiddle Cretaceous and earliest Tertiary time As already discussed, the contacts of several elongate (Gabrielse, 1985). The southern extension of the Manson bodies of Wolf Ridge gabbro arefaulted. It seems probable fault zone ultimately feeds into the McLeod Lake -North- that their shape is, in part, the result of movement within ern RockyMountain Trench right-lateral fault systems the Manson fault zone. which appear to have been active in Early Tertiary time. Northwest of the map area,the Manson fault zone extends into the ConglomerateMountain area which is TIIMING OF MOVEMENT underlain by Late Cretaceous to Early Tertiary sediments The timing of movement on the Manson fault zone of theUslika Formation (Eisbacher, 1974). Apull-apart mustpostdate compression and imbrication of the basin related to movement on the Manson fault zone is a Quesnel, Slide Mountain and Cassiar terranes in Early to possibledepositional setting for these conglomerates. If Middle Jurassic time. Further refinement of the lower age this is true, movement is in part Late Cretaceous to Early limit of movement is provided by a 134 Ma K-Arage Tertiary. This interpretation is consistent with the evidence detwnination on maripositefrom an alteredultramafite provided by other small basins of Cretaceous and Tertiary body in the fault zone. Quartz-carbonate-mariposite altera- sediments found throughout the northern Cordillera.

Plate 36. Sleep fall contact hetween Slale Creek argillites (left) and Manson Lakes ultramafics (right) along the Manson fault zone. immediately southwest of Manson Creek.

71 EXTENSIONS OUTSIDE THE MAP AREA Fem e? al. (1992a.b and 1993a, b) andNelson et al. (1993a, b) who have demonstrated the presence of a large South of the map area, the Manson fault zone can be northwest trending strike-slip fault. projected into a major fault mapped by Struik and North- cote (1991) in the southwestern quadrantof the Pine Pass sheet. This structure connectswith a major fault system in theMcLeod Lake map area and ultimately into the RELATIONSHIP TO WOLVERINE FAULT McLeod Lake fault system (Struik, 1989b). ZONE Northern projection of the fault zone is less straight- Therelationship of theWolverine fault zone to forward. Northwest of the map area, it can he traced into regionalstrike-slip motion was addressed earlier. the Conglomerate Mountain area, but there are no major Gabrielse (1985) first postulated the relationship between lineaments that may be a topographic expressions of the strike-slip motion and uplift of metamorphic core com- fault.The only possibility is inthe upper part of the plexes. Some workers, such as Evenchick (1988) inthe Osilinka River, although Roots(1954) did not mention the SiftonRanges and H. PIint [personalcommunication, presence of a major fault zone within the underlying rocks 1991) in the Horseranch Range, have demonstrateda rela- of the Hogem batholith. This evidence suggests that the tionship between core complex uplift and regional strike- Manson fault zone is losing expression to the north. slip motion. Movement along the western hounding fault Roots (1954) mapped a series of faults or fault zones (Wolverinefault zone) of theWolverine Metamorphic northwest of Conglomerate Mountain, along the lower Complex has been accommodated by dip-slip motion. Its part of Vega Creek, along sections of Tenakihi Creek, and eastern boundary is marked by the right-lateral Northern along the Tutizika River. These zones form a northwest- Rocky Mountain Trench fault. Thus some typeof relation- trending belt and can be extendedinto a major fault along ship between uplift and strike-slip motion is inferred in the the Lay Creek valley which separates Takla rocks from study area. those of the Lay Range assemblage. The fault lineament The moderately to steeply dipping Wolverine fault along these creeks is en echelon withthe Manson fault zone must be cut or joined at depth by the near vertical zone. It is postulated that motion on the Manson fault zone Manson fault zone. Crosscutting relationshipsbetween the istransferred to an en echelon fault along the Vega- fault systems are unknown. Timingof fault motion on both Tenakihi-Lay Creek valleys and that this displacement fault systems is similar and regionally the Wolverine fault feeds into theFinlay and Ingenika faultsystems to the zone appears to feed into the McLeod Lake - Northern northwest. RockyMountain dextral fault systems: a situation This northwestward extension of the Manson fault exemplified by the Manson fault zone as it merges with zone has been supported byrecent mapping in the area by the Wolverine fault zone at depth.

12 METAMORPHISM

INTRODUCTION wanites) in the Manson fault zone (see chapter on Eco- nomic Geology). It is possible that there is an unconfor- Rocks in the map area were variably metamorphosed mity between the Slate Creek succession and the Manson during the Mesozoic andCenozoic. Regional metamor- Lakes ultramafics (evidence discussed in Geological Syn- phism is, for the most part, chlorite grade or lower within thesis chapter) and that the abundance of iron in Slate the Intermontane Belt and is probably of Mesozoic age. In Creek sediments may, in part, be dueto erosion of material the Omineca Belt rocks reach sillimanite grade and record from the ultramafics. MiddleJurassic and Early Tertiary thermal events.This Actinolite, biotite and garnet are widespread within v:lriability retlects the differenttectonic histories of the the contactaureole of the Germansenbatholith. The two belts. Rocks of the Intermontane Belt were deformed aureole extends up to 2 kilometres into the sediments and at a much higher structural level than those of the Omineca volcanics of the Takla and Boulder Creek groups. North- Belt. east of Mount Gillis. Takla mafic volcanic rocks contain actinolite which commonly forms radiatingmasses cen- INTERMONTANE BELT tredon augite or hornblende phenocrysts; biotite Regionalmetamorphism in theIntermontane Belt (stilpnomelane?) is concentratedin the volcanicmatrix. al:tainedchlorite grade. Biotite and garnet grade Tiny porphyrohlasts of garnet are found within interbed- a!;semblages are seen locally, but represent contact meta- ded argillites and calcareous argillites of the Slate Creek morphism related to the Germansen batholith. succession near Mount Gillis. North of Mount Germansen, Generally, metamorphic grade increases to the east. nematoblasticactinolite and biotite form afoliation in In western exposures, mafic volcanics of the Takla Group conjunction with flattened volcanic clasts. contain prehnite and pumpellyite in association with chlorite, epidote, calcite andmuscovite. These mineralsare OMINECA BELT found as vein andvesicle fillings and as alteration of A characteristic of the Omineca Belt is the presence rlatrix material. To the east, prehnite and pumpellyite are ofdynamothermal metamorphism which culminates ahsent and Takla and Lay Range volcanics contain chlo- withinregional-scale sillimanite-grade core complexes. rite, muscovite, epidote and calcite, indicating a slightly Rocks of the Omineca Belt represent the infrastructure of h~gher metamorphicgrade. the orogen in the eastern part of the Cordillera. Pelitic rocks contain chlorite. muscovite and quartz; The metamorphic grade of the Omineca Belt within whereas epidote is common in the more tuffaceous sedi- the map area ranges from chlorite grade in its western pan ments. Close to the Manson fault zone, silvery muscovite- to sillimanite grade in the east. Metamorphic grade gradu- rich slates may containsignificant amounts of iron-rich ally increases to thenortheast with an abrupt increase carbonatewhich locally form large porphyroblasts across the Wolverine faultzone. North of theOsilinka (Plate 37). The presence of carbonate porphyroblasts in River, metamorphic grade increases east and west of the thesesediments usually corresponds with thenearby headwaters of EdmundsCreek, as indicated by the occurrence of stronglyaltered ultramafic bodies (list- appearanceof staurolite to the east and the coarser schistose nature of the rocks to the west. Sillimanite-grade rocks fom a northwest-trending belt confined to the lower parts of the lngenika Group in the Wolverine Range. Displacement on the Wolverine fault zone has jux- taposed sillimanite grade rocks against rocks of garnet and lower grade. Apparentdisplacement on the Wolverine faultdecreases to the north resulting in thelimited appearance of staurolite and kyanite just northwest of the confluence of the Omineca and Osilinka rivers. The lack of outcropand the poordevelopment of kyaniteand staurolite have preventedthe delineation of offset isograds. However, isograds are definitely truncated by the Wolverine fault; whereas, elsewhere they roughly parallel the dominant structural trends. There is a general concordance between metamorphic gradeand stratigraphiclevel, with chlorite-grademetamorphism persisting down to the upper part of the Swan- Plate 37. Photomicrograph of idiomorphic ankerite por- nell Formationand increasing below this level. In the phyroblasts in Slate Creek argillites near the Motherlode show- western pan of thearea the biotite isogradconsistently ing. Also seen in this picture is a xenomorphic ankerite occurs below the Espee Formation whereas, in the east, a parphyroblast. thick carbonate believed to be the Espee Formation, is at

73 staurolitegrade. The Wolverine antiform has broadly idioblastic to xenoblastic and are parallel to subparallel to warped these isograds into domal surfaces. the dominant foliation. They can also be poikiloblastic and Metamorphismreaches staurolite grade within the may exhibit an hourglass structure. The chloritoids com- Boulder Creek group where tentative garnet and staurolite monlycontain oriented inclusions of the groundmass isogradshave been mapped (Figure 7). Metamorphic material aligned parallel to the fabric in the groundmass. grade increases tothe southwest within the Boulder Creek They donot overgrow a later pressure-solution crenulation group and peaks southwest of Lower Manson Lake in an cleavage (S2, Plate 38). area of limited outcrop where staurolite and garnet-grade At one locality a chloritoid crystal has grown at a assemblages appear to terminate against the southwestern high angle to the layer-parallel foliation (SI). This folia- boundary of the group. The presence of greenschist grade tion appears to be slightly “bowed” or flattened around metamorphic rocks in the Takla Group southwest of the theporphyroblast (Plates 38, 39). In thissample most Boulder Creek group indicates a faulted boundary betweenchloritoid porphyroblasts are oriented subparallel to SI the two units. foliation,though many are alsoat a high angle to SI foliation. This, in conjunction with the slight flattening of S, foliationaround some of theseporphyroblasts, indi- MINERAL ISOGRADS cates that they grew late during D, deformation. Progressivemetamorphism of theserocks is illus- Very smallcrystals of chloritoidwere observed in tratedby mineral isograds defined by the presence of schists of the Boulder Creek group. They are idioblastic to porphyroblasts (Figure 57). These isograds (in ascending xenoblastic and have grown parallel or subparallel to the grade) mark the appearance of chloritoid, biotite, garnet, dominant foliation. staurolite, kyanite and sillimanite. Some of these diagnos- tic minerals occur only locally and an isograd cannot be TOURMALINE mapped (e.& chloritoid, staurolite and kyanite). A brief description of each metamorphic facies, with reference to Porphyroblasts of tourmalineare seen at all meta- various structural elements, follows. morphicgrades above the biotite isograd. Relatively unmetamorphosedIngenika Group sediments contain abundant detrital grains of tourmaline and it seems proba- CHLORITOID blethat the porphyroblasts were produced by the Chloritoid porphyroblasts up to several millimetres in recrystallization of this material. This is substantiated by length are found in the upper parts of the chlorite zone the outlines of detrital grains within idioblastic crystals of (Plate 38). This mineral is only locally developed; conse- tourmaline. quently,it has not been possible to define a chloritoid Tiny, idioblastic tourmaline porphyroblasts occur at isograd. Its presence and textural relationships define the several localities east of the garnet isograd (biotite zone). relative age of foliations. In contrast, near Edmunds Creek (staurolite zone), tour- Chloritoid appears to be confined to pelitic rocks of maline occurs as large porphyroblasts up to 2 centimetres theIngenika Group where it persistsinto garnet-grade long. In thin section these porphyroblasts are poikiloblas- rocks.It occurs as single porphyroblasts that are sub- tic with straight inclusion trails (Plate 40).

Plate 38. Photomicrograph of a chloritoid porphyroblast in phy- Plate 39. Photomicrograph of chloritoid porphyroblasts in schists llites of the lngenika Group. The chloritoid overgrowsand makes of the Ingenika Group. This chloritoid overgrows theS, foliation a high anglewith the S, foliation. SI isalso slightly bowed but it is pre-S, as seen by the deflection of S, cleavage planes around this chloritoid crystal, indicating that the crystal grew late around its edges. during D, deformation.

74 Figure 57. General geology of the map area showing the location of isogrdds and occurrences of chloritoid, tourmaline, staurolite and kyanite. Also shown is the geochronology of the high-grade metamorphic rocks. m=nmscovite, b=hiotite, h=hornblende, w=whole roc.<

75 Plate 40. Photomicrograph of tourmaline porphyroblast in Plate 41. Photomicrograph of recrystallized (annealed) biotite schists of the lngenika Group. and muscovite crystalsin the central or high-grade regions of the Wolverine Metamorphic Complex. Compare this with the fabric within the ductile ponion of the Wolverine fault zone (Plate 31). BIOTITE The biotite isograd was mapped continuously through GARNET rocks of the Ingenika Group. The first occurrence of this The traceof the garnet isograd closely mimics that of mineral typically corresponds with the lower levels of the the biotiteisograd. Itstrace withinthe BoulderCreek Tsaydiz Formation or upper parts of the Swannell Forma- block is tentative due to the sporadic occurrenceof garnet. tion. This isograd can bemapped from the Osilinka River Garnet is extensively developed in the southeastern por- southeastward towards the Wolverine Range, where it ter- tion of the mapsheet where a well-defined isograd follows minates against the Wolverine fault zone. To the south it is the trend of the Wolverine fault zone. restricted to small fault blocks of upper Ingenika Group Garnet porphyroblasts arered to pinkish red in colour rocks in the vicinity of Granite Creek. and up to 2 centimetres indiameter. Theyare almost The first biotite porphyroblasts seen in the lngenika always equant and v"y from xenoblastic to idioblastic, Groupoccur as tiny crystalsoriented parallel orsub- though the latter are uncommon (Plate 42). Poikiloblastic parallel to SI foliation. Biotite porphyroblasts, up to sev- textures are common. and in some cases inclusions forma eral centimetres across, may occur at higher metamorphic crude layering within the porphyroblast which is always at grades. They may be poikiloblastic and the inclusions are an angle to the dominantfoliation inthe rock. Garnets oftenrandomly oriented. These porphyroblasts aretyp- with heliciticinclusion trails are very rare(Plate 43). ically xenoblastic andthe S, foliation commonly wraps Locallypoikiloblastic porphyroblasts form veryirreg- aroundthem. Above thesillimanite isograd, biotite and ularly shaped, "ragged" crystals(Plate 44). Thesefre- otherphyllosilicates are recrystallized as shown in quently contain a rim rich in quartz and feldspar inclu- Plate 41. Here,biotite and muscovite crystals are sions. The larger, more equant, idioblastic porphyroblasts recrystallized around F, fold hinges and show little inter- are usually found in the mostpelitic rocks, whereasragged nal strain. Biotite in the lower grade metamorphicrocks is com- monlychloritized. Typically chloritization is incomplete and remnants of the original biotite can he seen in thin section. Recrystallization resulting in large, single crystals of chlorite is not evident. Two generations of biotite are observed in samples from the Boulder Creek group. Oneis represented by tiny xenoblastic porphyroblasts growing parallel to subparallel to the main foliation. These increase in size with the grade of metamorphism.The second group are subidioblastic and grow at an angle to the dominant foliation. In some sections these discordant porphyroblasts are poikiloblastic and have inclusion trails parallel to the exterior foliation. There is no post-growth flattening of the SI foliation. Many of these biotite crystals are orientedparallel to a late Plate 42. Photomicrograph of idioblastic garnet porphyroblast crenulation but some appear to be randomly oriented. in schists of the Ingenika Group.

76 Plare 43. Photomicrograph of garnet porphyroblast with helicitic inclusion trails which indicates that metamorphism was Occur- Plate 45. Photomicrograph of retrogressed garnet porphyroblast riy during D, deformation. within schists of the Ingenika Group. In this picture S, foliation is flattened around the garnet indicating that deformation outlasted the peak of metamorphism (if the peak of metamorphism corresponds to porphyroblast growth). Also seen in this photo are S, crenulations which cut across S,.

STAUROLITE Staurolite is only recognized in afew localities; in the far northeastern comer of the map area and within the Boulder Creek group (Figure 57). In the northeast, near Edmunds Creek, staurolite occurs as large porphyroblasts LIPto 2 centimetres long. They may be idioblastic, though commonlyonly a fewcrystal faces arewell formed (Plate 46). They arepoikiloblastic with the inclusions forming a crude layering parallel to the long axis of the porphyroblasts (Plate 47). These inclusion trails (and the long axis of the staurolite crystals) are often at an angle to thedominant foliation which wraps around the porphyroblasts.

Plate 44. Photomicrograph of irregularly shaped garnet porphyrohlast within schists of the lngenika Group. porphyroblasts are moretypical of quartz and feldspar-rich lithologies. The SI foliation commonly wraps around garnet porphyroblasts (Plate 45) though in some samples SIfoliation i!; relativelyunaffected (Plate 42). F, crenulations are deflected (Plate 45) by garnet porphyroblasts. In the lower amphibolite facies, garnet is often retro- gressivelyaltered to chlorite, muscovite and quartz (Plate 45). The original nature of these pseudomorphs is &en difficult to distinguish in the field. Garnet was only observed in a few localities in the Eloulder Creek group where it usually occurs as small, red to brown idiomorphic porphyroblasts up to 0.5 centimetre in diameter. In thin section it displays the same textural Plate 46. Photomicrograph of subidiomorphic staurolite por- rm-lationships as staurolite with the other fabric elements phyroblast in Ingenika Group schists showing poikiloblastic tex- (,we section below on relationships of metamorphism to ture. These inclusion trails make a high angle with the surround- dlefonnation). ing foliation which suggests post-growth deformation. Plate 47. Photomicrograph of staurolite porphyroblast showing Plate 48. Photomicrographof subidiomorphic staurolite por- layered inclusion trails at a high angle to foliation. These trails phyroblast from within the Boulder Creek block showing straight arealso slightly curved. This indicates synmetamorphic D, inclusion trails anddeflected crenulation cleavage. This photo deformation with deformation outlasting metamorphism. also shows biotite porphyroblasts growingwithin the S, cleavage planes.

Plate 49. Photomicrograph of kyanite porphyroblast at the edge Plate 50. Photomicrograph of sillimanite needles (fihrolite) of a staurolite porphyroblast in lngenika schists. nucleated on mica grains in lngenika schists.

Plate 51. Migmatite (?) in amphibolite gneiss of unit Pipi north of Munro Creek.

78 Staurolite forms porphyroblasts up to 0.5 centimetre RETROGRADE METAMORPHISM long within the Boulder Creek group. They areidioblastic Retrogrademetamorphism or alteration variably and poikiloblastic, with the inclusion trails parallel to the dominant foliation (S,, Plate 48). The long axes of the affects metamorphic minerals in the map area. It is most pronounced in thegarnet and biotite zones and rarely crystals also parallel the S, foliation and there is no post- growth flattening of the SI foliation.A late crenulation observed at higher metamorphic grades. Retrogression is most evident alongthe west flank of the metamorphic cleavage is deflected by the staurolite porphyroblasts. complexand is very apparent near the Wolverine fault zone. It is believed that the Wolverine fault zonemay have KYANITE localized this retrogression. The brittle and ductile parts of Kyanite is found in only two samples in the Edmunds the fault zone must have had a greater permeability than Creek area where it is associated with staurolite. It forms the surrounding rocks. The fault zone may have acted as a tiny (less than 0.5millimetre) subidioblastic crystals conduit for magmatic, meteoric andor metamorphic fluids (Pl.lte 49) growing parallel to the dominant foliation. whichproduced retrograde assemblages within adjacent higher level rocks. SILLIMANITE Sillimanite is presentthroughout the Wolverine RELATIONSHIP OF METAMORPHISM Ranges (Figure 57). It is difficult to identifyat the outcrop, TO DEFORMATION but is typically seen in thin section in the form of fibrolite (Phte 50).In the Munro Creek area sillimanite forms large Rocks of the Omineca Beltdisplay clear textural crystal masses up to several centimetres long. These por- relationships that are readily interpreted within the context phyroblastshave formed at the expense of garnetand of a regional deformational-metamorphic history. define a southto southeast-trending suhhorirontal Figure 39 shows the timing relationships between defor- lineation. mation and metamorphism within the Omineca Belt. Rela- tionships in the Omineca Belt are directly applicable to In thin section sillimanite is observed replacing phyl- rocks of the Intermontane Belt as the processes (ie., tec- losilicates(Plate 50). These porphyrohlasts are either tonic events) which brought these belts together, and sub- needle-likecrystals within thecores of muscoviteand sequently deformed them, produced similarly aged struc- biotite grains or fibrous mats alongthe edges of micas. tures and metamorphism within each belt. However, the character of thesestructures and metamorphic events is MIJSCOVITE-OUT (?) manifested differently within each belt; the Omineca Belt High-grade metasediments containing only biotite are generally records deeper, more ductile processes and the found in thenortheastern part of the Wolverine Range IntermontaneBelt contains higher and more brittle within unit Pipi . The mineral assemblage in these rocks is features. biotite, quartz, potassium feldspar, plagioclase and occa- sionallygarnet. Thisassemblage may reflectthe disap- INGENIKA GROUP (CASSIAR TERRANE) pearance of muscoviteand indicate a higher grade of Relationshipsbetween porphyroblasts, fabrics and metamorphism in the northeast but it should be noted that regional-scale structural elements appear to be consistent these rocks did not contain sillimanite and many of the within theIngenika Group. Straightinclusion trails in reactions which consume ~nuscovitehave sillimanite as a chloritoid, garnet and staurolite porphyroblasts (Plates 38, product (Winkler. 1979). Thus the lack of muscovite may 39, 43, 45 and 47) indicate that the S, schistosity predates reflect the bulk composition of the rocks rather than very main-stage metamorphism. Helicitic textures in some por- high metamorphic rank. phyroblasts (Plates 43, 47)indicate that the peak of metamorphism occurred during D, deformation. Furthermore, MlGMATITE (?) semi-randomly oriented porphyroblasts (Plates 38.39) and Quartzofeldspathic layer-parallel lenses up to several little or no flattening of SI foliationaround some por- decimetres long and 10 centimetres wide occur rarely phyroblasts (Plate 42) suggest the peak of metamorphism within theamphibolite gneisses north of MunroCreek was (very) late during Dl, probably towards its close. (Plate 51). The presence of this migmatite-like material is In all samples abovegreenschist grade metamor- probably related to increasing metamorphic grade to the phism, the dominant schistosity is flattened around larger southeast in theWolverine Range. These migmatitic porphyroblasts (Plates 47. 52). If garnets grew at the peak bodies suggest partial melting of the metasediments. of metamorphism, clearly deformation extended beyond Alternativelythe quartrofeldspathic lenses may the metamorphic peak. Straight to slightly helicitic inclu- represent highly dismemberedpegmatitic material. In siontrails in garnet, tourmalineand staurolite are pre- high-grade rocks north of the Manson River, pegmatites served at a high angle to the main schistosity. This again are foliated and boudinaged within the main foliation to suggests that the first deformation outlasted the peak of produce thin bodiessimilar in appearance to the mig- metamorphism. matites. In these pegmatites there is agradation from East of the Wolverine faultzone, minerals within relatively undeformedto boudinagedsections. No such rocks at predominantly sillimanite grade show little or no gradationor internal fabric was observed in the internal strain. Thesame holdstrue forschistose rocks quartzofeldspathic lenses in the Munro Creek area. north and east of the Osilinka River. All phyllosilicates

79 GEOTHERMOMETRY Garnet-biotite geothermometry hasbeen conducted ontwo samples (FFe87-35-7and DMe87-33-7; see Figure 57 for locations)of sillimanite grade rocks from the Ingenika Group. A total of 43 microprobe analyses were conducted using the ARL microprobe at the University of Calgary: 26 on garnetand 17 on biotite.Mineral stoichiometries were calculated using microcomputer pro- grams written by G. Poirier at McGill University. Garnet analysesare normalized to eight cations and all iron is assumed to be ferrous. Biotite stoichiometries are based on fourteen cation sites using the method of Dymek (1983). Microprobe analyses and mineral stoichiometries are presented in Appendix V. Garnets in these samples are manganese-rich alman- dine with MnO contents ranging from 3.4 to 8.5%. Biotite has a relatively constant composition. Chemical zoning is not apparent in either of these porphyroblastic minerals. Plate 52. Photomicrograph showing foliation wrapping around Temperatures have been calculated on averaged min- garnet in schists of the Ingenika Group. eral analyses using the methods of both Ferry and Spear (1978) and Hodges and Spear (1982). Ferry and Spear’s application is limited to systems that do not contain significant amounts of calcium,manganese, and titanium; and quartz show annealed textures indicating that meta- that is only if (Ca+Mn)/(Ca+Mn+Fe+Mg)=0.20 for morphismoutlasted deformation (D, and D,). The garnet and (Alvi+Ti)/(Alvi+Ti+Fe+Mg)=O.15 for bio- annealed textures imply that temperatures remained high tite. For minerals that do not meet these chemical specifi- enough to remove anyacquired strain. We suggest that cations the methods of Hodges and Spear should be used. these rocks remained relatively deep and above the hlock- Temperatureresults calculated using both geother- ing temperatureof metamorphic minerals until Early Terti- mometers are presented in Table 5. Due to the chemical ary time when the complex was rapidly uplifted. restrictions listed above, the results for sample FFe87-35-7 mayhe better estimated using Hodges and Spear’s West of the Wolverine fault zone, micas and quartz methods,whereas sample DMe87-33-7 may hebetter show little evidence of annealing.The mineral grains approximatedusing Ferryand Spear’s techniques. Both exhibit undulose extinction and polygonization indicating samples produce results which are virtually indistinguish- post-peakmetamorphic strain, probably related to D, ablewithin the error estimates of the calibrations deformation. (250°C). Temperaturescalculated using rim analyses yield BOULDER CREEK GROUP (KOOTENAY results similar to those obtained from the cores of min- TERRANE) erals, withthe exception of sampleDMe87-33-7. The extremely high temperature obtained for the garnet-biotite The metamorphism in the Boulder Creek peak of rimpair in sampleDMe87-33-7 mayindicate disequi- block is S, mica post-Dl and pre-D,, although growth librium in the sample. Overall, temperatures are assumed suggests that metamorphism may have continued at least to representpeak metamorphicconditions. The results to the onset of D, deformation. This is also suggested by stauroliteporphyroblasts that contain straight inclusion trails aligned parallel to thelayer-parallel fabric in the TABLE 5 enclosingrocks which is not flattenedaround the por- GEOTHERMOMETRY RESULTS FOR SAMPLES FFe87-35-7 phyroblasts.Crenulation cleavage planes (S,) are AND DMe-87-33-7. deflected around these staurolite porphyroblasts. GEOTHERMOMETRY RESULTS Biotite crystals are locally developed parallel to S, cleavage planes and also at angles to SI and S, indicating SAMPLE FFE 35-7 I FERRYAND SPEAR I HODGES AND SPEAR that metamorphism may have outlasted both Dl and D, I deformations.Timing relationships between metamorphism and deformation within Boulder Creek strata are somewhat different from the relationships seen in the most of the Omineca Belt in the map area. In the Boulder Creek SAMFlEDMES7 I FERRYANDSPEAR I HOCGESANDSPEAR group the peak of metamorphism is clearly post-D, and GmT+1-.e+ammr I Ear I 670% may hesynchronous with theonset of D, deformation whereas in the Ingenika Group the peak of metamorphism coincides with Dl and clearly pre-dates D, deformation.

80 range from 620" to 650°C for the preferred calibrations and older ages are obtained for rocks in the hangingwalls and are consistentwith expected temperatures for rocks of of the bounding faults. Such evidence indicates that the sillimanite grade. shear zoneswere active in Early Tertiary times and that the K-Arages of metamorphic rocks in thesecomplexes represent cooling due to rapid uplift in the Tertiary and do GEOCHRONOLOGY AND TECTONIC not representa thermal reset of earliermetamorphism IMPLICATIONS (Brown and Can; 1990). Metamorphic cooling ages were determined for seven According to this theory, strata of the Omineca Belt samples from high-grade metamorphic rocks of the Inge- were thickened and metamorphosed in the Earlyto Middle nika Group (Figure 57, Appendix 11). Rocks east of the Jurassic. Rocks in the upper parts of the deformed CNS~ Wolverine fault zone returned Early Tertiary ages (33-59 wereuplifted justafter Middle Jurassic deformation. Ma) whereas a sample from the hangingwall of the fault Rocks in the deeper pans of the continental crust (core produced a Middle Jurassic age (171 Ma). A specimen in complexes) remained above the K-AI blocking tempera- or near the fault zone yielded a Late Cretaceous age (82 tures of metamorphicminerals until Late Cretaceous to M.1). These data are consistent with peak metamorphism Early Tertiary time, when they were quickly uplifted along in MiddleJurassic time, but withrocks east of the extensional shear zones. Wtslverine fault zone reset in the Early Tertiary. The 82Ma salnple may record Middle Jurassic metamorphism that is Structural and metamorphic data within the map area only partially reset. are consistent with this hypothesis. Early Tertiary metamorphic ages inhigh-grade rocks within the Wolverine Early Tertiary datesare quite common in meta- Range are separated from older metamorphic ages by the morphic rocks around the study area (Figure 58) and in west-side-down Wolverine faultzone. Exposed meta- corecomplexes of the southern Omineca Belt(Parrish, morphicmineral assemblages in the Wolverine Range 1979; Parrish e/ ai, 1988). Recent work in core complexes require uplift in the order of 20 to 30 kilometres of which a of the southern Canadian Cordillera has shown that they large portion may have been accommodated by motion on are bounded by moderate to steeply dipping normal faults the Wolverine fault zone. Rocks in the hangingwall of the orshear zones (Parrish et ul., 1988;Carr et a/. 1987). Wolverine fault zone represent upper crustal regions that High-graderocks of the core consistentlyreturn Early were cooled through normal denudation processes follow- Tertiarymetamorphic cooling ages whereas Cretaceous ing their deformation and metamorphism. Uplift of the Wolverine Complex appears to have been very rapid as gauged by apatite fission-track analysis of two samples. The morereliable of these samples shows the complex cooled below 100°C at approximately 48 Ma (Figure 57). Takenin conjunction with K-Ar blocking temperatures and ages of metamorphic minerals, this indicates cooling fmmapproximately 500°C to 100°C in a few million years. implying rapid uplift of these rocks in the Early Tertiary. Evidence for unroofing of the complex immediately following annealingand cooling of apatite grains is provided by the presence of metamorphic detritus in the Early Tertiary SiftonFormation exposed in the northern Rocky Mountain Trench (Gahrielse, 1975). An 82 Ma K-Ar date from near the fault zone also points to uplift and cooling of rocks in Late Cretaceous time.Cretaceous uplift is furthersubstantiated by the occurrence of metamorphic clasts in the Late Cretaceous to Early Tertiary Uslika Formation immediately northwest of the maparea (Roots,1954). However, most metamorphiccooling agesare Early Tertiary indicatingthat Cretaceousdates record theonset of a mainly Tertiary uplift event. Middle Jurassic dates on prograde metamorphic minerals from the Omineca Belt are well documented in the southern Canadian Cordillera (Greenwood er a/., 1991), hut are poorly represented in the Omineca Mountains. In the Chase Mountain region, immediately north of the map Figure 58. Regional geology map with K-Ar dates along the area, Panish (1979) ohtained a date of 166 Ma from RhlSr Omineca Belt and parts of the Rocky Mountains. Data from this ratios on muscovite from a schist. This led him to postu- study, Parrish (1979). Gabrielse (1975) and Wanless dol. (1979). late that metamorphism was of Middle Jurassic age with rn=muscovite. b=biotite, h=homblende, w=whole rock. thermaloverprinting or upliftin the Early Tertiary. A

81 similar age obtained in the map area further corroborates The cause for upliftof these complexes is not known. Parrish’s Chase Mountain data as well as detailed studies Brown and Cam (1990) suggest that it was the result of to the south. isostaticinstability in thehighly thickened crust imme- Metamorphism in the southern part of the Omineca diately after the cessation of contractional deformation. Mountains appears to be more or less synchronous with Alternatively, Evenchick (1988) clearly demonstrated the metamorphism in the southern Omineca Belt. Such wide- relationship between strike-slip motion and the uplift of spread synchronous deformation ultimately reflects hinter- high-grade Tertiary rocks in the Sifton Ranges. A similar land accretion of allochthonous terranes. Docking of these relationship exists for uplifted metamorphic rocks of the terranes probably occurred at about the same time along Horseranch Range (Plint et al., 1992). the length of the Cordillera. The Wolverine Metamorphic Complex is boundedon The Wolverine Metamorphic Complex appears ter-to its northeast side by the dextral northern Rocky Mountain minate at the northern end of the Wolverine Range but Trenchfault system. The southern extension of the Tertiary extension northwest of the map area is expressed Wolverine fault zone joins the McLeod Lake fault system by other metamorphic culminations. One such area is the which is amajor right-lateral fault. Furthermore, other southern part of the Butler Range which has consistently complexes in the region (such as the Butler Range com- yieldedTertiary metamorphic cooling ages (Gabrielse, plex) are bounded by faults which are part of strike-slip 1975). The Butler Range is bounded on each sideby steep fault systems. Uplift of the Wolverine and related com- slopes which fall off into straight valleys oriented parallel plexes is believedto be linkedto transcurrent motion tothe Wolverine fault zone. It seems probable that the along the Northern Rocky Mountain Trench and related Butler Range represents another uplift that is en chelon dextralfaults (Gabrielse, 1985; Struik, 1988~;Parrish with the Wolverine Metamorphic Complex. et al., 1988; Evenchick, 1988; Plint et al., 1992).

82 ECONOMIC GEOLOGY

TheManson Creek and Germansen Landing areas colloform, banded, crustiform, vuggy or drusy textures), have a longexploration history dating back to thelate these veins are classified as mesothermal. 1800s whenplacer gold wasfirst discovered. Hardrock The veins can be divided into three main groups (I, II exploration has been fairly sporadic since the late 1800s and 111) based on theirproximity to theGermansen but hasled to thediscovery of 45 mineral occurrences batholithand the Manson fault zone. Type 1 veins are within the confines of the map area (Figure 59, Table 6). associated with theGermansen batholith. Type II veins 01’these 45 occurrences, three were discovered in the occur along the Manson fault zone and can be subdivided course of this project (the Dog Creek, Dave and Whistler on the basis of wallrock alteration, vein mineralogy and occurrences). host formation. The three subgroups are: Ila) veins having Mineral showings in the map area can be grouped low copper values and carbonate wallrock alteration pre- inlo twelve occurrence types. Most of the occurrences (21) dominant oversilicification; IIb)veins containing are related to vein mineralization and there are only one or tetrahedrite and with silicification predominant over car- two examples of the remaining groups. This variation of bonatealteration in thewallrocks; and IIc) veinsfound occurrencetypes reflectsthe presence of four diverse primarily in sedimentary rocks and only silica alteration in teuanes within the map area. The following descriptions the WdIlrOCkS. and accompanying tahle of mineral occurrences (Table 6) This division is similar to both Lay’s(1939) and broadly outlines distinctive characteristics of each occur- Armstrong and Thurber’s (1945) who classified the veins rence type (Figure 60). only on the basis of observed mineralization. Appendices to this report include a series of litho- geochemical analyses of mineralizedand unmineralized I - BATHOLITH-RELATED VEIN SYSTEMS rocks (Appendix VI) and the geochemistry of standard and Polymetallic veins near the Germansen batholith are hulkstream-sediments. and moss-mat samples(Appen- hosted by Takla Group metasediments. They are close to dices VI1 to IX). The locations of these samples are shown the batholith (between 0.5 and 2 kilometres) and wallrocks on Figure 8. exhibit only silica alteration. They characteristically contain galena, sphalerite, pyrite and minor pyrrhotite; molyb- POLYMETALLIC VEINS denite is conspicuouslyabsent. Chalcopyrite may also Twenty-one polymetallic vein occurrences have been occur with the lead and zinc sulphides. The veins carry documented in the area. Based on the sulphide mineral- variable amounts of silver and little or no gold. They are of ogy, lack of epithermal mineralsand vein textures (no varying thicknessesand generallystrike in aradiating pattern outwards from the batholith. TheBlackhawk prospect (MINFILE 0Y3N 0221, locatedapproximately 5 kilometres south of Manson Creek, is typical of theseoccurrences. The following details are summarized froma report by Campbell (1989). Its history dates back to the 1930s. A short adit has been driven along one of the larger veins and the prospect was drilled by NorandaExploration Company, Limited in 1989 This occurrence comprises at least nine quartz veins rangingbetween 0.3 to 3 metreswide (Armstrong and Thurber.1945; Lay, 1939; Campbell, 1989). The veins strike north to northeasterly (approximately perpendicular to the batholith contact) and dip steeply to the west. The 30-metre zone containing the veins is intensely silicified and, in places, stockworks of small quartz veinlets have formed. The hostrocks arehomfelsed Takla siltstones,calcareousshales, argillites and minor argillaceous limestones.Purple to darkgreen, silicified andfine-grained metasiltstones predominate. Where observed. bedding is contorted or masked by small quartz veinlets. Pervasive silicification obliterates most of the original sedimentary

Both massive and disseminated sulphides, including Figure 59. Mineral occurrence location map of the project area argentiferousgalena, sphalerite, pyrrhotite, pyrite and (numbers correspmd tu map numbers in Table 6). minor amounts of chalcopyrite are present in the milky

83 POLIYETUUC

VBW

Figure 60. Schematic block diagram illustrating the relationship between general geology and mineral occurrence types. Numbers represent Occurrence types. 1) polymetallicvein deposits; 2) strataboundbase metal deposits; 3) disseminatedgold deposits; 4) silicified shear zone deposits:5) carbonatites; 6)sulphide-rich amphibolite gneiss deposits;7) porphyry molybdenum (copper) deposits, 8) ultramafic-related dewsits: 9) stratiformbarite deposits; IO) sedimentarymetamorphic (graphite) deposits; I I) disseminated shlphide deposits; 12) Rkre emh rich alkalic intrusivei. quartz veins. Where massive, the most abundant sulphide The hostrocks area mix of carbonatized andsilicified ispyrrhotite with some sphalerite. A sampleacross 1.5 ultramafiteand sediments. The altered ultramafic rocks metres returned assays of 1399 grams per tonne (40.8 oz/ (listwanites) are talc-ankerite-mariposite schist. The car- ton) silver, 3% lead and 3% zinc (Lay, 1939). A 3-metre bonatizationis so intense thatthe sedimentscommonly chip sample alongthe extension of the main vein returned containankeritic porphyroblasts. The alteration halo values of 2.14% lead and 416 grams per tonne (12.13 oz/ varies in width and typically terminates abruptly. ton) silver. Two drillholes intercepted this vein system at The Bold 2 occurrence (MINF’ILE 093N 197) is located depth. The largest vein intersection was I metre wide and west of the Manson Lakes, just north of Boulder Creek contained 15% galena, 15% pyrrhotiteand 5 to 10% andshows most of the Type IIacharacteristics. It was pyrite. No further work was done on the showing as it was discovered in 1982 while exploring the Bold I (MINF’ILE felt the veins and vein system narrowed at depth (Camp- 093N 137) showing lower on the slope. bell, 1989). This occurrence is referred to as the “main showing” by Melnyk (1982) and is described as contorted quartz II - VEIN SYSTEMS RELATED TO THE veinscarrying pyrite, galenaand sphalerite with minor MANSON FAULT ZONE chalcopyrite and finely disseminated molybdenite flakes. Polymetallic veins in and near the Manson fault zone A grab sample collected by the authors returned analyses arehosted by ultramafite,carbonates, arenaceoussedi- of 90 grams per tonne silver, 9.5% lead, 127 ppm copper ments and fine-grained argillites.Within the fault zone, and 111 ppm zinc. Gold was undetectable in this sample theserocks (fault-boundedslivers) belong toeither the and molybdenum was not analyzed. Nina Creek, Takla or Boulder Creek groups. Although the The veins are predominantly quartz with the carbo- genesis of all veins isprobably related to the same event(s) nate wallrock alteration being associated with carbonate and they aresimilar to each other, thesevein systems veinlets. Mineralized veins strike easterly (80- 120”) and exhibit subtle differences and can be divided into three dip fairly steeply (70-80”)to the north. The width of the subgroups,based upon the hostrock alteration veins ranges from0.5 to 3 metres and the mineralization is assemblagesand to some extent, the nature of the “clumpy”galena, forming 1 to IO-centimetre patches mineralization. scattered irregularly across the vein. Disseminated pyrite, minorchalcopyrite, and calciteare also present in the TYPE IIA VEINS veins. Type IIa veins containa wide range of metals includ- The wallrocks arequartz muscovite schist of the ing lead, zinc, copper, silver and gold in a carbonate or BoulderCreek group in close proximity to intensely quartz gangue. Molybdenumand tungsten also occur, pos- shearedand altered Manson Lakes ultramafics.These sibly indicating a genetic link to the Germansenbatholith. ultramafic rocks are structurally interleaved with rocks of The veinsare typically less than a metre to several metres theBoulder Creek group along flat-lying thrusts which wide. have been cut by the Manson fault zone. 86 TYPE IIB VEINS ALTERATION Type Ilh veins always carry tetrahedrite and are asso- Carhonatization. in association with silicification, is ciated with ultramafic rocks. The hostrocks are silicified the most significant and widespread alteration type associ- and carhonatized. The veins are always contained within ated with vein and disseminated gold mineralization along the Manson fault zone and generally follow its northwest the Manson fault zone. trend.Both stockwork zones and discrete veinstens to This alteration is typified by large porphyroblasts of hundreds of centimetres wide are present. The typical iron carbonate (ankerite) which, when weathered, give the metals are copper, gold and silver. Copper sulphides are rock a rusty brown appearance. Typically mafic and ultra- -typically altered to malachite and azurite. mafic rocks exhibit the most intense alteration resulting in a rock composed of variableamounts of talc,ankerite, Wallrock alteration is somewhat similar to Subgroup mariposite,quartz, sericite and chlorite and commonly Ila in that it can be quite pervasive and end abruptly. Most referred to as a listwanite. Alteration zones vary in width hostrocks are less altered than in Subgroup IIa ser- (iz, and it is not uncommon to find tens of square metres of pentiniterather than talc-ankerite schists),although in listwanized shore of lowerManson some occurrences (e.&, Fairview) carbonate alteration is rock(north Lake). foliated hut in very intense in narrow zones around and within the vein They may be weakly to moderate many instances no fabric is present. These zones are fault con- sysems. . trolled and they commonly end abruptly against relatively TheFairview occurrence (MINFILE 093N 023) is unaltered rocks. The alteration can be so intense that it is located 0.5 kilometre northwest of Manson Creek and has often impossible to recognize the original lithology. been known since the early 1900s (Lay, 1939). It has been Ankeriticsediments are typicallysilicified and trenched several times during its history. The main vein exhibit a phyllitic to schistose sheen. They contain fine averages 1 to 3 metres in width with a known strike length sericite,albite and calcite additionto large por- of 48 metres. It hasbeen recentlyexamined by BP in phyroblasts of ankerite (Plate 37). Thesealtered sediments ResourcesLimited (McAllister. 1986: McAllisterand are usually close to listwanized ultramafics. Examples of Sandherg, 1988) and the following descriptions are taken altered sediments can be seen near the Motherlode show- from assessment reports. ing (MINFILE 093N 024) and the QCM occurrence (MIN- Theoccurrence is within the Manson faultzone, FILE 093N 198). strikes southeast (155") and has a vertical dip. It is composed of massivewhite quartz, massiveankerite with An excellentexample of increasingcarbonate and patchysilicification (grading intothe massive quartz), silica alteration of mafic volcanic rocks can be found in a ankerite breccias with a quartz matrix, and ankerite within 15-metre-wideoutcrop along the old portion of the quartz stockwork. The massive quartzcontains blebs of pyrite, chalcopyrite andargentiferous tetrahedrite-tennanite with rel.ited malachiteand azurite staining. Visible gold has been reported. The most mineralized samples returned gold values up to 18 grams per tonne (the same sample retlurned 6.6 ppm silver and 152 ppm copper). Silver values range up to 85.73 grams per tonne. The veins are hosted hy mafic volcanics (and possibly the Wolf Ridge gabbro). They are strongly silicified. carbonatizedand sheared. Large porphyroblasts of ankerite are found in the wallrocks and mariposite is also present. These rockscontain anomalous goldand silver values. Other nearby veins containing pyrite and tetrahedrite are hosted in serpentinites, gabbros and argillites of the Nina Creek group.

TYPE IIC VEINS Type Ilc veins arecharacterized by the absence of carbonate alteration in the hostrocks. They are hosted by Talda and Nina Creek group sediments which are gener- Plate 53. Outcropof listwanitized augite-porphyriticTakla basalt all:y argillitesand are foundwithin or nearthe Manson between Manson Creek and Germansen Landing. Theleft side of fault zone. The occurrencesrepresenting this subgroup are the outcrop is strongly altered and containsa strong foliation;this known only from early reports by Lay (1939) and Arm- alteration quickly disappears to the right. Samples GRP 6, 7 and strong and Thurber (1945). Thelack of recent exploration 8 (of Figure 62) were taken in the area marked 'highly altered' for these veins reflects their low levels of precious metals. wifh ]he remaining samples collected from the area to ]he right. Thetypical minerals are galena, sphalerite and chal- Sample GRP X was taken from the far left of the altered zone and copyrite with little or no gold and silver. sample GRP I from the far right (see Figure 62 for data).

x7 Omineca mining road between Manson Creek and Ger- A chemical profile of this alteration wasobtained mansen Landing (see Figure 17 forlocation; Plate53; through whole-rock analyses (major and minoroxides, samplesGRP 1 to 8in Appendix 111). Thisoutcrop of and trace elements, Appendix 111) of eight samples collec- augiteporphyry basalt contains an alterationgradient tedacross the outcrop. The combined oxides showna gen- which displays the textural,mineralogical and chemical eraldepletion (Figure 61); MnO and CaO show erratic changes which occurred during the progressive alteration valuesacross the zone and increase slightly near the of these rocks. The intensity of this alteration increases to strongest alteration. Copper concentrations decrease con- the west where it is abruptly terminated by a fault. As the tinuously across the zone whereas zinc is not mobile until alteration increases,the rock takes on a moreschistose the alteration becomes very intense. The trends described appearance such that, at the western and most intensely here and portrayed in Figure 61 are typical of listwanized altered part of the outcrop, a moderateto strong foliationis mafic and ultramafic rocks found within greenstone belts presentand it is impossible todetermine the volcanic of the Precambrain shield (Boyle, 1979). protolith.This outcrop displays many of thecommon characteristics of carbonate alteration in the map area. PRECIOUS METAL QUARTZ VEINS The least altered part of the outcrop is strongly chlo- Only two precious metal vein occurrences are known ritized anddisplays a very weak penetrativefoliation. in the study area. These showings were reported by Lang Relic textures within the volcanic protolith are still dis- (1941, 1942). Theyare quartz-pyrite veins with low(?) cernible. The mostintensely altered section of the outcrop values of silver and gold found in metasediments of the has a moderate to strong foliation and exhibits the brown- Ingenika Group along Granite Creek (MINFILE 093N 132 weathering iron stain typical of listwanites. It is composed and 134). entirely of quartz, sericite, ankerite and mariposite, and the original rock type is indistinguishable. Ankerite is either found interstitially or as distinctive porphyroblasts. Iron- DISSEMINATED GOLD magnesiumsilicates (dominated by chlorite) are The only reported occurrenceof disseminated gold is increasingly replaced by iron carbonate and sericite as the the QCM prospect (MINFILE 093N 198). Anomalous gold, alteration increases within the transition zone. silver, copper andzinc values in soil and rock samples were first reported in this area in 1972 (Rodgers, 1972). This early soil geochemistry outlined twolarge anomalous trends; theFlag zone and the Central zone (Figure 62). Since 1972, this area has undergone extensive geological, geochemical and geophysical investigationwhich led to reverse circulation drilling in 1983 (Riccio, 1983). Rocks in the anomalous area are poorly exposed but are believed to belong to theTakla Group. Recent mapping inthe UslikaLake area by Ferri et al. (1992a,b), and Nelson ef a/. (1993a, b) in the DiscoveryCreek area suggests that volcaniclastics immediately southwestof the E Combined Fe203. FeO, COO. Mansonfault zone may belong to the Lay Range assemblage (see chapteron Lithologic Units). They are composed of volcaniclastics (tuffs and lapilli tuffs), lesser volcanically derived sediments and argillites, aphanitic to pyroxene-phyric flows and lesser cherts. Theargillites are > I thin to moderately bedded, cream to rusty weathering and grey on freshsurfaces. They are interbeddedwith cream to 10 \ $4 beige, thin to moderately bedded tuffs to tuffaceous silt- No20 stones in sequences 1 to IO metres thick. Less abundant K70 are thin to thickly bedded tuffs and lapilli tuffs with lesser volcanicsandstones, conglomerate and wackes. Clasts within these volcaniclastics aresubangular feldspar and augite crystalfragments, feldsparaugite porphyries, aphaniticvolcanics and minor argillite. Thehasalts are green to dark green, amygdaloidal mafic flows with small phenocrysts of pyroxene and plagioclase and commonly lo& ;;g.eL)0: lo& "GRP 1 GRP2 CRP CRP GRP GRPGRPGRP' containing a penetrative cleavage (Ferri, 1989). 34 5 670 All of these rock types havebeen affected, to varying degrees, by carbonate alteration with the main alteration minerals being ankerite and pyrite. Riccio et al., (1982) Figure 61. Chemical changes produced by the carbonate altera- distinguished two types of carbonate alteration, the first tion of a basaltic andesite near the Manson fault zone. See text characterizedby large porphyroblasts which have for details and Plate 53. poikiloblastic cores containing quartz, feldspar, hematite

X8 Figure 62. Simplified geology of the QCM claim group (modified from Ferri, 1989; Riccio ef 01.. 1982). and otheropaques, andthe second by idioblastic.iron- Surfacelithogeochernical sampling on thiszone poor porphyroblasts which may he related to the inclusion- returned gold values as high as 3.7 grams per tonne from free rims of the porphyroblasts of the first type. The only I-metre chip samples (Riccio et a/., 1982). The zone was sulphide recognized in these altered zones is pyrite which tested by four reverse-circulation drill holes which aver- forms up to 10% of the rock and is generally tine grained aged 100 metres in length. They all cutstrongly altered and idioblastic, volcanicsediments, as seen on surface.Median gold Alterationassemblages are varied anddependent values range from 0. I7 gram per tonne in Hole 1 to 0.13 upon lithology. In the mafic and intermediate volcanics the gram per tonnein Hole 4. In Hole2 a 5-metre section alterationassemblage is typically ankerite-alhite- averaged I .8 grams per tonne gold with a 1 -metre section sericite+quartz?maripositetpyrite and the volcaniclastic of 3.2 grams per tonne. Several I-metre sections returned rocks typically contain ankerite, sericite, albite and quartz over 1 gram per tonne gold. wlth or without pyrite. The most intensely altered zones Riccio et ai., (1982) point to a positive correlation ar': cut by abundant quartz veins of varying widths. between anomalous gold values and pyrite content, sug- The Central zone is some 200 by 300 metres in area gesting that the gold is within the pyrite. They also indi- and is hosted by volcaniclastic rocks of the Takla Group. cate that the intensely altered zones are quartz veined and The volcanics are bleached to a whitish or cream-coloured 50 the possibility that fine, freegold may he a vein constit- rock composedprimarily of sericite, quartz, iron carho- uent cannot he ruled out. However, they also note that gold na.tes, pyrite (5%) and albite, hut with very little quam has not been reported from theseveins and very little veining. The original clastic nature of these rocks is barely veining is present in this area which suggests that the gold discernible. may he disseminated in the altered volcanics. Theabove rock typesoccupy northwest-trending belts separated from each other by steeply dipping faults STRATABOUND BASE METAL rellated to the Manson fault zone (Ferri, 1989). As in areas to thesoutheast, numerous splays of theManson fault OCCURRENCES zonecontrol the quartz-carbonate-sericite (listwanite) Stratabound sulphidemineralization isconfined alieration. within a specific stratigraphic interval which ranges from

89 the Big Creek - Otter Lakes contact downwards to the uppermost sandy dolomitesof the Echo Lake group (sandy dolomiteunit). These are carbonate-hosted sulphide depositswith the typical sulphide assemblage being yellow to red-brown sphalerite, argentiferous galena, barite and minor pyrite (Melville, 1990; Ferri and Melville, 1990a).The sulphides occur as semimassive irregular pods incollapse breccias, massive lenses localized in shear zones, or as disseminated blebs in arenaceous dolomites. Germanium maybe associated with the sphalerite. Brecciated dolomites (collapse breccias) host semimassive sphalerite and galena together with megacrystic barite.Typical grades average 3 to4% sphalerite (Leighton, 1988) with variable galena (usually less than sphalerite);grades of greaterthan 15% combinedlead- zinc have been recorded (Ferri and Melville, 1990a). The sulphides also occur as clasts in a calcite-barite matrix; as matrix with carbonate clasts; or as a combination of both (Melville,1990). Tectonic breccias are similar tothe dolomitic breccias in terms of variable galena, zinc andbarite mineralization. Figure 63. Regional extent of favourable hostrocks for stratabound base metal (carbonate replacement) deposits (modified The sulphides occur either as semimassive irregular pods from Melville, 1990). (Leighton, 1988) or as the matrix of fault breccia (Son- nendrucker,1975). Mineralizationwithin the lowerOtter Lakes and lower Mississippian shales and Lower Cambrian carbo- upper Echo Lake groups is generally restricted to dissemi- nates and contain lead with Early Cambrian or older shale nated sphalerite in arenaceous dolomites, fine-grained dol- curve model ages. Bradford (1988) believes that the lead omites, and rarely, sandstones. The sphalerite occurs with in these deposits was remobilized along faults from lower minor amounts of galena and pyrite and may reach grades crustalregions during Devono-Mississippian rifting. A of 4% zinc (Sonnendrucker, 1975). similar process is theorized to have produced the occur- Atthe Biddy occurrence (MINF’ILE093N 114). the rences in the map area. trace element germanium is reportedly presentin amounts Figure 63 shows theregional extent of favourable averaging 0.05% of thesphalerite mineralization hostrocks,the local crosscutting faults and the known (Leighton, 1988). Germanium values in excessof 220 ppm mineraloccurrences. Mineralization is welldocumented havebeen reported in materialassaying 14.7% zinc alongthe southem exposure of thehostrocks. Detailed (Melville,1990). prospecting along this stratigraphic horizon elsewhere in Mineralized dolomitic breccias occur just below the the map area, will undoubtedly expose more occurrences. Big Creek shales and no stratabound lead-zinc mineralization has been found above this stratigraphic interval. This SILICIFIED SHEAR ZONE suggests that the shales acted as an impermeable barrier, (VOLCANOGENIC MASSIVE channeling the movement of mineralizing fluids through the Otter Lakes carbonates. SULPHIDE?) These occurrences share some similarities with the The Nina occurrence (MINFILE 093N 01 I, Figure 64) Midway Camp as they are found in the same stratigraphic is the only example of this deposit type found in the map interval, are not structurally complex, and occur as com- area and has been known since the 1940s (Armstrong and binations of matrix and clast replacement suggesting sev- Thurber, 1945).Since that time it has been examined era1 phases of mineral deposition. However, in the Cassiar sporadically and was drilled in 1988. It is located approx- area,larger deposits like Midway are mantos with a imately4.5 kilometres north of NinaLake andoccurs characteristicallycomplex sulphide suite (i.e., pyrite, within rocks of the Nina Creek group. It is characterized sphalerite,galena, pyrrhotite, friebergite, arsenopyrite, by arelatively simple mineral suite within a silicified pyargyrite, and tin and lead sulphosalts; Nelson, 1990) and shearzone. The shear zone is characterized by strong appear to be related to granitic intrusions of Cretaceous oxidation and appears red-brown within the green to grey- age. greensediments and volcanics. Its relationship to other Occurrences in the Germansen Landing - End Lake structuresin the map area is uncertain. Mineralization area, have much simpler sulphide mineralogy (primarily includes copper and silver sulphides, andgold in associa- galena and sphalerite) and the lead has a Cambrian shale tionwith pyrite. It hasbeen suggested by Watkinsand curve model age (C. 1. Godwin; personal communication, Atkinson (1985) that this prospect may be a sheared vol- 1990). These characteristics are similar to sediment and canogenic massive sulphide deposit. carbonate-hosted showings in the Cassiar area referred to Thehostrocks aregrey-green, fine-grained, as “old” by Bradford (1988). These deposits are hosted in pyroxene-porphyritic basalts intercalated with laminated,

90 nated pyrite (Cope. 1988). Epidote alteration is associated with the silicification (although not as pervasive). NINA !I NINA II ! The sulphides consist primarily of massivepyrite, I variable chalcopyrite and minor sphalerite (Watkins and 2 Atkinson, 1985). Gold and silver concentrations vary; the silver is in argentiferoustennanite and argentiferous SHOWING tetrahedrite. One grab sample from the property returned 2 an assay of 0.60 gramper tonne gold, 20.2 grams per tonne silver and 14.91% copper and another, 6.90 grams MAIN per tonne gold and 146.5 grams per tonne silver (Cope. SHOWING 2 1988).

m.tr.* CARBONATITES Figure 64 Geologyof the Nina claimgroup (modified from Carbonatites are representedin the project area by Cope, 1988). I - Siliceous argillite, varicoloured chert and gab- two elliptical, northwest-trending, sill-like bodies (Lonnie bro. 2 - Massivebasalt and basaltic breccia. 3 ~ Tuffaceous argillite andbanded chen. Blackareas are mineralized zones. and Virgil; MINFILE 093N 012 and 174). They are exposed in the southern part of the map area and are on strike from one another, along the ductile portion of the Wolverine che~ty,pale green tuffs. dark grey argillitesand gabbro fault zone. The country rocks. like the carbonatites, have sills. The sedimentary units are of variable thickness and beenmetamorphosed to amphibolitegrade and are strike northwesterly with moderate dips to the south. quartzites to garnet-biotite-muscovite schists of the Pro- The main shear zone (Figure 64) is 2 to 20 metres terozoic Ingenika Group. wide andstrikes northerly, dipping steeply to the west. Both carbonatite complexes are comprised of various Lenses of massive sulphides and silicified fault breccia are intrusiverocks which include biotite sovites, aegerine localized within it. The countryrocks contain dissemi- sovites, and syenites of possible Late Devonian to early

91 Mississippian age. There is a pervasive aureole of alkali the banding present in parts of these bodies may represent metasomatism(fenetization) in thesurrounding rocks relic structuresdue to metasomatization of thecountry which is typical of calcite carbonatites (Pell, 1987; Hal- rocks(A. Halleran, personalcommunication, 1991). A leran,1980). sample of aegerine-augite monzodiorite contained 0.27% The Lonnie occurrence was discovered by prospec- cesium; 013% lanthanum; 0.1% neodymium and 0.13% ting in 1953 and staked in 1954. It has subsequently been thorium (Halleran, 1988). These rocks also contain signifi- mapped, trenched and drilled. cant amounts of zirconium and yttrium. Some dikes con- The Lonnie carhonatite is approximately 50 metres tainminor amounts of chalcopyrite, malachite and wide and 460 metres long (Halleran, 1980). The complex magnetite. follows a northwesterly trendparalleling the Wolverine fault zone, and is comprised of numerous interfingering SULPHIDE-RICH AMPHIBOLITE intrusive rock types (Figure 65). GNEISSES Two varieties of carbonatite are described by Pel1 There is a single occurrence of sulphide-rich amphi- (1987); an aegirine sovite composed primarily of calcite, bolite gneiss located within high-grade metamorphic rocks microcline, perthite and aegirine, and a biotite sovite con- of the IngenikaGroup inthe southeastern edge of the tainingcalcite, biotite and usually plagioclase. The study area. The Manson River East Occurrence (MINFILE aegirine sovite occurs along the southwestern margin of 093N 180) was discovered during the 1987 field season in thecomplex and the biotite sovitealong thenortheast the course of work on this project. margin.These rocks are associated with syenite, monzonite and monzodiorite.All intrusive types contain a Visible mineralization consists of disseminated chal- pervasive penetration foliation parallel to that of the coun- copyrite and pyrite hosted by amphibolite gneisseslayered try rock. The biotite soviteis mylonitizedand faulted 10 to 30 centimetres thick. These gneisses areinterlayered against the micaceous country rocks. with hornblende-bearing granitic gneisses and cut by pegmatites. A grabsample returned an analysis of 0.12% Rareearth geochemistry on a sample of aegirine copper and 3 ppm silver; gold was not detected. soviteyielded anomalous strontium (I 1 547ppm), niobium(4578 ppm), zirconium (739 ppm), titanium These mineralized amphibolite gneisses may repre- (281 1 ppm). and yttrium (1 19 ppm)and reflects the miner- sent evidence of mafic volcanism resulting from a Pro- alogy which includes zircon, pyrochlore and columbite as terozoicrifting event in the lowermostIngenika Group primary minerals, and pyrite, pyrrhotite and ilmenorutile (T.HOy, personal communication, 1990). Similar amphi- as accessory minerals. The strontium most likely occurs as bolite gneisses are reported by Evenchick (1988) in the a form of strontium carbonate. Niobium pentoxide values Sifton Range to the north. There, they sit upon 1.85 Ga on the Lonnie prospect have been reportedas high as 0.3% basementgneisses and are believed to represent mafic over 7.5 metres for a length of 240 metres (Vaillancourt volcanics related to rifting. and Payne, 1979). Areomagneticmaps indicate that these mafic gneisses continue to the southeast of the map area, sug- RARE EARTH RICH ALKALIC gestingthat this area has potential for other similar INTRUSIVES occurrences. High-grademetamorphic rocks of the Ingenika PORPHYRYNEIN MOLYBDENUM Group containa series of rare earth element (REE) hearing monzonites to syenitesin the southeastern part of the study OCCURRENCES area (Will; MINFILE 093N 201). Theyare found about Porphyryoccurrences inthe maparea are concen- 2 kilometreseast of the MansonRiver, approximately trated in the northeastern partof the CretaceousGer- 5kilometres northeast of the mouth of MunroCreek. mansenbatholith and its surrounding metamorphic These intrusions are coveredby the large Visaclaim block aureole.The hostrocks are granites, granodiorites and centred to the southeast, within NTS 0930/012 (Halleran, hornfelsed Takla sediments. 1988). These REE-rich intrusions were first discovered in Mineralization occursas disseminations, fracture fill- 1986during detailed work around the Mon graphite ings or in veins. Disseminated flakes of molybdenite occur occurrence. in rocks near the intrusive contact. At the Blackjack East These bodies are differentiated from the carbonatites occurrence (MINFILE 093N 1 IS), easterly striking fracture becausethey are considerablyyounger, probablyEarly fillings, quartz veins and veinlets carrying small rosettes Tertiary, and by theirlack of abundant sovite. They intrude of molybdenite are found in both hornfels and intrusive paragneisses and schistof unit Pia of the Ingenika Group. rocks(Sinclair, 1969). Typical sulphide assemblages Rare earth concentrations are localized in small bodies of includepyrite, molybdenite, minor chalcopyrite, and aegerine-augite monzonite and monzodiorite which may rarely, pyrrhotite. show banding. They are associated with aegerine-augite The Jordi Occurrence (MINFILE 093N 133) is located syenite dikes andalkalic feldspar - aegerine-augite syenite on a steep north-facing slope approximately 2 kilometres dikes (Halleran, 1988). The monzonite is also related to northeast of MountGillis. The molybdenite is found in numerousquartz-feldspar, aegerine-feldspar-quartz and feldspar-quartzTmuscovite veinscutting biotite quartzpegmatites. The monzonites and monzodiorites monzonites and granodiorites of the Germansen batholith lack the strong gneissosity present in the countryrocks and (Helsen,1981).

92 UILTRAMAFIC MINERALIZATION 3 to 7metres and their lateral extent is limited dueto faulting. They are characteristically fine grained and con- Numerous slivers of serpentinizedultramafic rocks tain a dark striping parallel to the foliation in the slates. occur withinthe Manson fault zone. These bodies host The layering is dueto opaque impurities of unknown chromite,pentlandite(?), and chrysotile occurrences. origin.Although these barite bandsappear to replace Placer concentrates from theimmediate area sometimes quartz-rich layers, they also indicate that the deposit may co!ntain platinum (Davies, 1983). haveformed as a sedimentaryexhalate (McCammon, TheNRS prospect (MINFILE093N 135) predates 1975). regional metamorphism; disseminated chromite is found The Big Creek group is equivalent to the Earn Group in serpentinized zones (Lang, 1941). which, in the northern Cordillera, hosts several large lead- Serpentinizedultramafics from the Ah Hoo Creek zinc-barite sedimentary exhalative deposits (Tom, Jason, ocl:urrence (MINFILE 093N 116) are reported to carry up to Stronsay(Cirque) suggesting the potential for similar 0.18% nickel occumng in pentlandite (Lay. 1936). Sam- occurrences in the area. ples collected from various serpentine bodies within the M;msonfault zone during the course of theproject returned nickel valuesbetween 0.12 and 0.17% which SEDIMENTARY-METAMORPHIC probably represent the original nickel content of serpen- (GRAPHITE) OCCURRENCES tinized olivines. TheGermansen River occurrence (MINFILE 0Y3N Metamorphism of organic rich (carbonaceous) Pro- I IS) is alow-grade chrysotile asbestos showing (Arm- terozoic sediments of the lowermost Ingenika Group, pro- strong and Thurher, 1945). duced graphite concentrations in upper amphibolite grade rocks in the Wolverine Range. These rocks include mar- STRATIFORM BARITE OCCURRENCES bles, calcsilicate gneisses and biotite schists. The only documented graphite showing is the Mon (S'EDIMENTARY EXHALATIVES) occurrence (MINFILE 093N 203) locatednortheast of Stratiform barite occurs in slates and argillites of the Munro Creek. Graphite occurs asdiscrete flakes or asthin Big Creek group at the Omineca Queen occurrence (MIN- layers. The graphite flakes are 1 to 5 millimetres in length FLE 0Y3N 087). The sectionsof barite reach thicknesses of and reach concentrations as high as 4.7%(Halleran. 1985).

Figure 66. Placer gold producing drainages within the project area

93 The graphite layers can be as thick as 6 centimetres and Holland, 1950) and gave rise to the Manson Creek placer are hosted by calcsilicate gneisses. gold camp. The earliest exploration concentrated on the gold-rich gravels along these two rivers and then moved on to their tributary creeks. Evidence of early placer work DISSEMINATED SULPHIDES abounds, including kilometre-long flumes and large open (PORPHYRIES?) cuts in gravel beds produced by hydraulic mining (Plate Two poorly documented showings of disseminated 2). sulphidemineralization occur withinTakla Groupvol- Total gold productionfrom this area is unknown. canics (MINFILE 093N 147 and 153). Minor chalcopyrite Holland (1950) reports gold production prior to 1950 for and pyrite occur in massive to fragmental augite-phyric the Germansen River at 515 845 grams (16 585 ounces); basalts and basalticandesites (Armstrong and Thurber, the Manson River, 358 025 grams (I1 51 I ounces); Lost 1945; Geology, Exploration and Miningin British Colum- Creek, I1 385 grams (366 ounces), and Slate Creek, 100 bia, 1972) 340 grams (3226 ounces). Current placer gold mining activity consists mainly of small operations on the past-producing streams (Figure PLACER DEPOSITS 66). A large operation on the Germansen River, near the Placer gold was discovered on the Germansen River old Germansen town site, operated roundthe clock during in 1870and on the Manson River in 1871(Kerr, 1934; the 1988 season.

94 GEOLOGICAL SYNTHESIS

TICCTONIC MODEL Thick successions of amphibolite gneiss and paragneiss unique to unit Pia (see Table I) may be situated near Stratified and igneous rocks of the Manson Creek - the base of the lngenika Group in the map area. No other Germansen Landing area record a geological history that amphibolite is seen in higher lngenika strata. Tens of spms the latest Precambrian to the present. These rocks kilometres of deformed strata have been removed by ero- form part of fourseparate tectonostratigraphicterranes sionduring uplift on the Wolverine faultzone in the whichrepresent rocks of oceanicaffinity to thewest Manson River area. This has resulted in the exposure of (Intermontane Superterrane) and continental rocks of the thelowermost parts of theIngenika stratigraphy. Mafic Onnineca Belt to the east (Figure 5; Monger, 1984). Most gneisses of unit Pia may represent metamorphosed flows rocks within the map area are older than Jurassic and were or sills emplacedduring rifting of thepre-Windermere deformed by crustalshortening beginning in the Early basement. Thick sequences of metaquartzite at the base of Jurassic, although there is evidence for similar deforma- the lngenikaGroup in theSifton Ranges (Evenchick, tion of Permian age (Klepacki and Wheeler, 1985, Harms, 1988) are lacking in the basal parts of unit Pia, implying 1986). The geologic sequenceof the Omineca Belt records stratigraphy slightly younger than the basal quartzite and long periods of stable shelf development, punctuated by amphibolites in the Sifton Ranges, but old enough to have several rifting events prior to compressional deformation. recorded rift-related igneous activity. Rifting episodes led to the formation of the oceanic Nina Coarse clasticsof the middle Swannell Formation are Creek group (or Slide Mountain Terrane) and the ocean- succeeded by finer clastics and carbonates of the upper warddevelopment of an arc complex (Lay Range Swannell, Tsaydiz, Espee and Stelkuz formations. Thus, assemblage, Harper Ranch Suhterrane), Thiswas followed erosion of the highlands and production of lower coarse by collapse of the NinaCreek basin and subsequent clastic units was succeeded by shallow water deposition of development of theQuesnel arc. Deformationand east- carbonate strata (Mansy and Gahrielse, 1978). ward transport of Slide Mountain, Lay Range and Quesnel rocks led to their present configuration. Mineralizing epi- Some authors suggest that Windermere rifting didnot sodes during this long history are restricted to periods of lead to continental break-up (Bond et al., 1985; Devlin and deformation and arc construction. Bond, 1988; Struik, 1987: Roots. 1987). Theypropose that episodic rifting produced a large intracratonic basin which Thefollowing discussion is by no meansentirely persisted until latestProterozoic or earliest Cambrian original. It evolvedfrom absorbing ideas from Rees times (Devlin and Bond, 1988). (1'387), Struik (1987; 1988a,c), Schiarizza (1989), Even- Mineralization related torifting and intracratonic chick, (1988), Nelson and Bradford (1993) and of course basin sedimentation occurs within the area. Copper- countless articles on Cordilleran evolution which are too map bearing amphibolite gneiss of unit Pia may represent sul- numerous to mention here. What follows an attempt to is phidemineralization associated with Proterozoic rift- imegrate data from the present map area with that from related volcanism. Graphite-rich calcsilicate bands, inter- otlher studies of the Intermontane-Omineca Belt boundary layered within unit Pia, represent highly metamorphosed, in hopes of producing a refined model that is applicable organic-richlimestones and may potentialhosts for along the length of the Canadian Cordillera. be carbonate-replacement.massive-sulphide mineralization.

PlPOTEROZOIC EARLY PALEOZOIC A major Proterozoic extensional event affecting the Early Paleozoic miogeoclinal sedimentation was ini- length of the western edge of the ancestral craton resulted tiated with deposition of Lower Cambrianbasal ortho- in widespread deposition of continental terrace sediments quartzites of the Atan Group which are succeeded by finer of the Windermere Supergroup (Figure 67a, Evenchick. clastics and carbonates of the upper Atan Group. Carbo- 1988; Mansyand Gabrielse, 1978). Basalamphibolite nate deposition predominated until the end of the Middle gneiss and quartzite of the lngenika Group in the Sifton Devonian(Otter Lakes group)forming amiogeoclinal Ranges (and Misinchinka Group in the Deserters Ranges) wedge characteristic of passive, continental margins (Fig- m.ay represent latest Proterozoic igneous activity and sub- ure 67h). sequent deposition of basal clastics related to initiation of Early Paleozoic sedimentation presumably occurred Windermere sedimentation over 1.85 Ga graniticbase- in response to extensional tectonism and subsequent ther- mcnt(Evenchick, 1988). Lower feldspathic and quartz mal subsidence following continental breakup in earliest wackes of the lngenika Group are probably high-energy Cambrian times (Devlin and Bond, 1988). Alternatively, deposits shed from highlands composed predominantly of Struik(1987) suggests that episodic rifting occurred horst blocks of Precambrian basement. Theoldest rocks in withinthe intracratonic Windermere basin until final the map area belong to theUpper Proterozoic Ingenika breakup in the Late Devonian. Although the culmination Group, the lower parts of which have been strongly meta- of rifting was undoubtedly adiachronous event, an earliest morphosed and in part form the Wolverine Metamorphic Paleozoic breakup is most consistent with the geology of Complex. the Manson Creek area and areas to the north.

95 Figure 61. Schematic diagram depicting evolution of the study area from Late Proterozoic to present. Set ? text for details. MFZ=Manson fault zone; NRMT=Northem Rocky Mountain Trench: WFZ=Wolverine Fault Zone.

96 An unconformityseparates Proterozoicand Lower tectonism.Big Creek shales contain stratiform barite Cambrian rocks in many parts of the Cordillera. but evi- (Omineca Queen) and basal shales overlying the Vernon dence for a sub-Cambrian unconformity is lacking in the showing contain disseminated sulphides; both are related map area. Instead, deposition of Lower Cambrian ortho- to exhalative.extension-related processes active during quartzitewas preceded by coarsening-upwardsimpure basin formation. Sedimentary exhalative mineralization is quartzites of the upper Stelkuz Formation that probably quite common in Upper Devonian to lower Mississippian representinitial immaturesediments shed from uplifted shale sequences in the northern Cordillera. blocks. As the blocks continued to be eroded, water depth decreasedand a possible concurrent eastward transgres- PALEOZOIC sion led to the deposition of the mature quartz sands of the LATE LowerCambrian (Devlin andBond, 1988). Post-rifting The oldest rocks of oceanic affinity within the map subsidencefollowing continental breakup led to stable area are the Pennsylvanian to Permian Nina Creek group miogeoclinaldevelopment and re-established deposition of the Slide Mountain Terrane. Elsewherein the Cordillera of thick carbonate sequences. Carbonate depositionwas fossils as old as early Mississippian (Nelson andBradford, nut dominanteverywhere; tine tocoarse clastics were 1993; Roots, 1954; Struik, 1988a;Schiarizra andPreto, deposited in deeperen\,ironments such as the Ospika 1987)provide a maximum agefor the Slide Mountain ernbayment to the northeast (Thompson, 1989) and in the (Nina Creek) ocean basin. Furthermore, initiation of rift- Cariboo area to the south (Struik, 1988a). ing along the continental margin roughly corresponds to Carbonate deposition ended by latest Devonian time, theoldest volcanics within theSlide Mountain Terrane and was succeeded by thick accumulation of Big Creek (early Mississippian) implying that this rifting led to the shales and argillites. Shale deposition occurred in response formation of the Slide Mountain basin. to another widespread rifting event along the western edge We argue that rifting resulted from back-arc spread- of the miogeocline (Gordey er ul.. 1987). This blanket of ing in lateDevonian time (Figure 67c and d). Arc, and shalereached far to the east within themiogeocline subsequent back-arc basin development, was initiated at (Thompson, 1989).In the map area, deep water deposition the continental edge, perhaps over a distal piece of North of predominantlyfine clastics continued until Permian Americancrust produced during earlyPaleozoic conti- time,punctuated briefly to the east of themap area by nental break-up. The Lay Range assemblage may repre- carbonate of theCarboniferous Prophet Formation sent the western arc. Evidence for this arc can be found (Thompson, 1989). In far northern British Columbia, the elsewhere in the Cordillera (Nelson and Bradford, 1993: EarnGroup (Big Creek group equivalent) contains Smith, 1974; Roots, 1954; Monger er a/., 1991; Ferri er a/. sequences of clastic material which may have formed from 1992a. 1993a).Parts of this arc are exposed within the the erosion of upliftedblocks produced during rifting QuesnelTerrane, but inour model, most of the arc is (Ciordey el u., 1987). Devono-Mississippian argillite and buried by theproducts of subsequentLate Triassic to shale of the map area contains minor coarse to fine clastics Jurassic arc volcanism (Figure 679. (quartz-chertwackes to sandstones of theBig Creek In the Lay Range, immediately north of the map area, group) and felsic volcanics (Gilliland tuff) related to this Roots (1954). Monger (1977a) and Ferri et a/. (1992a. b; event.Similar sequences of this ageare reported by 1993a. b) describe tuffaceous sediments, mafic to inter- workers all along the belt (Nelson andBradford, 1993; mediate flows and volcaniclastics, conglomerate and lime- Struik, 1988a: Schiarizzaand Preto, 1987). Furthermore, stone of Mississippian(?) to Permian age. These rocks are Devonian to Mississippian alkaline intrusions in the map time equivalents of the Nina Creek group and appear to area (Lonnie and Virgil bodies) are typically produced in occupy the same structural position. Such lithologies are areas undergoingextensional tectonism. Similar bodies not typical of theNina Creek group andreflect higher also occur along the length of the Cordillera (Pell, 1987). energysedimentary deposition andexplosive volcanism Rocks of theBoulder Creek group, and other associated with an arc. They may be proximalhack-arc sequences within the pericratonic Kootenay Terrane com- sediments: that is, material being shed off an active arc to prise Windermere stratigraphy which is overlain by lower the west. Nina Creek rocks represent deeper, more distal Plleozoicdeeper water clastics (Struik, 1987, 1988a). pans of the basin wherelow-energy sedimentation pre- Theyare assumed 10 represent distal, highly attenuated vailed. Volcanism in the mature Nina Creek basin was by pieces of the North American landmass produced during extrusion of typical mid-ocean-ridge basalts. Initial back- Cambrian and Devonian continental break-up. arc, basinal volcanism may have had an arc or transitional signature but as spreading continued and the basin wide- styles of mineralization in the Manson Creek Several ned, effectsof thisarc on basin volcanismdiminished. area can be related to this period of extension. Alkaline irltrusions contain significant amounts of rare earth ele- Rare polymict sandstones in the Mount Howell suc- ments(Pell, 1987). Carbonate-hosted sulphide occur- cession are most likely distal tongues of turbidic sediment rances in the Otter Lakes group (Vernon, Biddy, efc.)may from the western Lay Range arc. Clast composition is very hsve formed during rifting. Leadlead isotope studies of similar to feldspathic sands and conglomerates of the Lay several of these deposits indicate lead of Cambrian age (C. Range assemblage. 1. Godwin, personal communication. 1990). This old lead Farther north, in the Cassiar area, Division Ill of the musthave a lower crustal source andmay have been Sylvester allochthon contains many indications of an arc remobiliredalong normal faults related to extensional built on the western margin of the Slide Mountain basin.

91 Division 111, as a whole, represents pieces of an obducted Sedimentary evidence along the length of the Cor- islandarc. It occupiesthe highest structural position dillera suggests that the Slide Mountain basin was margi- within the allochthon indicating that it originated from a nal to the continent. In the map area, rocks of the Nina more westerly position than the underlying ocean-floor Creekgroup represent deposition in thecentre of the basalts of Division 11. Division I11 contains fragmental basin, with little influence from the western arc system or basalts, intermediate volcanics, shallow water limestones North American continent to the east. This is notonly with chert beds and gabbroic to granodioritic intrusions reflected in the sedimentary record, but also in the geo- (Nelson and Bradford, 1993). Interspersed with the frag- chemistry of the volcanic rocks where rare-earth element mental basalts are thick sections (100 metres)of volcanic plotsindicate typical MORB signatures with nocon- sandstone. Trace and rare-earth element plots for basalts tamination from continentalmaterial or from arc volca- within this section have an island-arc signature (Nelson nism. But, as recorded by the Mount Howell succession, and Bradford, 1993). Nina Creek rocks were still close enough to a continental source (i.e., North America) to receive influxes of quartz- Inthe southern pan of the Quesnel Terrane,late rich sand. Paleozoic arc-related volcanism may be manifest within North of the map area, the Slide Mountain Terrane rocks of the Upper Devonian to Permian Harper Ranch preserves both western and eastern margins of the basin Group.These predominantly fine-grained sedimentary (Lay Range assemblage, Sylvester allochthon).In the Syl- rocks contain notable sequences of fragmental volcanics vesterallochthon, Nelson and Bradford (1993) found andmassive flows (Monger et al., 1991). Smith(1974) quartz-rich sands within Divisions I and I1 and concluded studied Harper Ranch sediments in detail and concluded thatthese rocks were derived from the nearby North that they were derived from an active arc to the west. American continent. As previously discussed, thestruc- Basement to the Lay Range - Harper Ranch - Sylves- turally highest Division I1 comprises pieces of the western ter Division 111 arc systems is believed to be continental in arc. origin (as suggested in Figure 67c and d). Evidence for In the Adam Lake area, Schiarizza and Preto (1987) continental basement below these arc systems comes from describe thick sandstoneswithin the lower Fennell Forma- several localities. Conglomeratelenses within thesedi- tion,indicating proximity to a continentalsource. mentary and volcanic sequencesin the Lay Range contain Schiarizza (1989) also concluded that the lower Fennell clasts of igneous and metamorphic composition (see also Formationwas deposited along the North American Roots, 1954; Ferri et al., 1993a). The only eastern source margin. forthese conglomerates wouldhave been rocks of the Klepacki and Wheeler (1985) have demonstrated the Canadian Shield which, at its westem edges, was buried equivalency of the Kaslo and Milford groups; the latter below some 3 to 4 kilometres of miogeoclinal sediments. restsunconformably on North American rocks. This The high-energy nature of these sediments precludes dis- clearly showsthe marginal nature of the KasloGroup tally exposed shield rocks as a source. There is no evi- sediments and volcanics. dencefor uplift anderosion of shieldmaterial in the Omineca or Foreland beltsprior to Tertiary time.This PERMIAN TO TRIASSIC material must, therefore, be derived from western uplifted In the map area, as in the rest of the Cordillera, an and eroded blocks of the arc core. Farther north, detrital exceedinglywidespread unconformity encompasses the zircons recovered from Division 111 sediments yield Pre- UpperPermian to Middle Triassic internal (Readand cambrianages, suggesting a continentalsource (J.L. Okulitch, 1977). In the Quesnel and Slide Mountain ter- Nelson, personal communication, 1993). ranes, sedimentation resumed in the Middle Triassic with Rare-earthelement signatures fromTakla Group the deposition of basinal shales. basalts in the study area suggest the existence of conti- The basal contact of the Middle to Upper Triassic nentalmaterial below the Takla arc.Ratios of yttrium Slate Creek succession is not apparent inthe map area against zirconium suggestcrustal contamination or assim- because is has been cut off by the Manson fault zone. In ilationresulting from eruption on top of continental Quesnellia, basal Triassic slates commonly lie with angu- lithosphere (see under Takla Group, Figure 38). However, lar unconformity over upper Paleozoic rockswith possible the Takla arc is believed to have developed above the Lay Slide Mountain affinities (Monger et al., 1991; Read and Range arc (Figure670. This doesnot negate the existence Okulitch,1977; Little,1983). Exposures in thesouthern of the Lay Range arc, it simply suggests both arc systems partof Quesnellia indicate an angular unconformity are floored by a fragment of continental crust. Although between units of the Slide Mountain assemblage and the not analyzed, basaltic Y/Zr ratios of the Lay Range vol- overlying Slate Creek equivalents. Klepacki and Wheeler canics are expected to be similar to those of the Takla (1985) have shown the Lower Permian (to Middle Tri- Group. assic, Gordey et al., 1991) Marten conglomerate restswith The original width of theSlide Mountain basinis angular unconformity on greenstones of the Kaslo Group unknown. The breadth of thisback-arc basin would be (Nina Creek group equivalent). The Upper Triassic Slocan dependent on the lengthof time subductionwas active and Group (equivalent to the SlateCreek succession) rests on plate geometries at that time. Rees (1987) estimated a disconformably on the Marten conglomerate. This rela- basin several hundred kilometres wide, based on structural tionship requires uplift, tilting and erosion of the Kaslo reconstructions in the Quesnel Lake area. Struik (1987) Groupduring Permian or EarlyTriassic time. In the assumed a width of approximately 150 kilometres. Quesnelarea, McMullin et al. (1990) report conglom-

98 ~~

erates (Wingdam conglomerate) possibly within the Mid- ted withinparts of Quesnellia and probablyblanketed dle 1.0 Upper Triassic black phyllite, which contain meta- deformed(?) rocks of the Slide Mountain Terrane. Sedi- morphic,sedimentary and ultramafic clasts presumably mentation on the miogeocline consisted of shallow water derived from the underlying Crooked amphibolite (Slide clastics which were succeeded by Upper Triassic carbo- Mountain assemblage) and SnowshoeGroup. This con- nateshoals of the Baldonnel Formation (Thompson, glomerate may be of Jurassic ageand unrelated to the 1989). Permo-Triassicunconformity (McMullin et ai., 1990; In the Upper Triassic, shales of the Slate Creek suc- Struik. personal communication, 1993). If it is Triassic in cession pass upwardsand westwards into volcanic silt- age then it also implies uplift anderosion of the Slide stones, sandstones and conglomerates shed from the emer- Mountain assemblage in LatePermian to EarlyTriassic gingUpper Triassic Quesnel arc. This arc was time,prior to deposition of theblack phyllite. In the superimposed on the Lay Range arc. Itsformation was due Casiar area, the basal contact of the Upper Triassic Table to the eastward subduction and consumption of the Cache Mountain Formation sediments is believed to represent a Creek oceanic crust (Monger et ai., 1982; Monger, 1984). faultedunconformity above sedimentary and volcanic Arc volcanism and related sedimentation continued until rocks of the Sylvester allochthon (Nelson and Bradford, the Early Jurassic (Figure 670. 1993). Huge coeval alkaline tocalcalkaline magmatic bodies Direct evidence for this uplift is not seen in the map intruded Takla volcanic rocks (Hogem batholith). Many of area but has been documented elsewherein the Cordillera. these produced porphyry systems with significant copper In the Kaslo area. Klepacki andWheeler (1985) report andcopper-gold concentrations (e.&, MountMilligan). thrusting (Whitewater thrust) which is plugged by a Per- mian pluton. An analogous relationship is described by LATEST EARLY JURASSIC TO LATE Harms (1986) in the Sylvester allochthon. In the Yukon, JURASSIC Erdmer (1987) describes eclogites and blueschistfacies roclcs of Permo-Triassic age. In the southwestern United Obduction of the collapsed Slide Mountain basin and States. rocks very similar in age and composition to the theQuesnel arconto North Americaoccurred in latest Slide Mountain assemblage wereimbricated in Permo- Early Jurassic to Middle Jurassic time (Figure 67g). Time Triassic time, during theSonoman Orogeny (Silberling constraints are based, in pan.on metamorphiccooling and Roberts, 1962; Silberling, 1973). dates from the map area and the southern Omineca Belt In the Manson Creek area, the basal parts of the Slate (Greenwood el ai.. 1991). Obduction resulted from the Creek succession contain sequences of very tine grained, closure of the Cache Creek basin and the collision of the quartzosesands andsiltstones. Bloodgood (1990)also Stikinelandmass withthe Quesnelarc. Pre-obduction describes thick (up to 150 metres), quartz-rich sandstone SlideMountain basin configuration is unknown as the sequences at thebase of theMiddle to UpperTriassic extent of imbricationduring Permian basin-collapse is black phyllite unit in the Quesnel Lake area. Prograding only speculative. However, the present stacking order of epiclastics of the Takla arc, that contain little or no quartz, lithologies within the Slide Mountainassemblage is a are found above these quartz-rich sediments. A source for retlection of the original configurationof the various units. the basal quartzose sands may have been the continent to Telescoping has preserved the most westerly part of the the east. The implications of this and the preceding para- basin in theuppermost part of the thruststack. This graphs are enormous. We know that clastic sedimentation implies that thePillow Ridge basalts represent deeper, was occurring in Middle and Late Triassic time along the more distal parts of the Nina Creek - Slide Mountain basin miogeocline to the east(Thompson, 1989). Basal Slate and that the siliceous sediments of the Mount Howell Creek succession must have been deposited close enough succession were deposited closer to North America and tothe continental margin toreceive abundant quartz may, at one time, have rested on ocean-floor basalts. A detritus which the underlying Nina Creek sediments lack. similar arrangement of thrust sheets is even more evident This suggests that the Nina Creek or SlideMountain basin in the Sylvester allochthon, where the most westerly parts had partially or totally collapsed by Late Permian to Early of the Slide Mountain basin (represented by arc volcanics Tri,asric time (Figure 67e). and sediments of Division 111) sit structurally above basinal basalts,ultramafics and sediments of Division 11, Basin collapse probablyled to obduction of Nina which in turn reston Division I sediments of North Ameri- Creekrocks onto distal parts of theNorth American can affinity. Repetition of thispattern of imbrication is miogeocline (;.e., KootenayTerrane). There is however, apparent in other areas underlain by the Slide Mountain no evidence within North American rocks of the Cassiar assemblage. Terranefor compressional deformation and metamorphism of Permian or Triassicage. Constraints on this Evidence for timing of obduction in the map area is compressionalevent in Kootenay, Slide Mountainand provided by a 171 Ma K-Arcooling age for meta- Quesnel terranes are limited and the regional extent of this morphosedProterozoic rocks in thehangingwall of the detormation is speculative. Wolverine fault zone. We argue that the emplacement of the Nina Creek group on top of the miogeocline resulted in concurrent thickening, heating and metamorphism of the MilDDLE TRIASSIC TO EARLY JURASSIC lower continental CNUSI.Differential thickening along the By the end of the Middle Triassic, basinal shales and length of the continental succession through folding and limestones of the Slate Creek succession had been deposi- faulting in conjunction with obduction of oceanic rocks

99 resulted in metamorphicisograds crosscutting withinthe Foreland basin to the east. This basin was stratigraphy. formed beginning in the Early Jurassicby downwarping of Obduction led to the developmentof easterly directed the lithosphere in response to loading of the continental D, structures and a ubiquitous layer-parallel fabric. This crustto the west. Emergent western landmasses, which fabric is pronounced in relatively deeply buried and hotter caused the loading, also provided the sediments deposited rocks, or in incompetent units. No large-scale, northeast- in the Foreland Basin. Large clastic wedges of the Fore- directed nappes were mapped in the study area, but con- land Belt are known to he separated by major unconfor- siderablethickening of the sedimentary package is mities(Thompson, 1989)which must have formed in believed to have occurred at this time. Thickening led to responseto major tectonismand uplift to thewest. the emergence of a significant landmass which shed sedi- Directly northeast of the map area, the lowermost clastic ments into the contemporaneous foreland basin to the east. wedge of the Foreland Belt comprises the Early Jurassic to First occurrences of westerly sourced detritus in the fore- earliest Cretaceous Fernie and Minnes groups (Thompson, landare recorded by thePassage beds of theMiddle 1989) and probably represents loading and detritus pro- Jurassic Fernie Formation (Thompson, 1989). duced during D, and D, deformation. The nextclastic Duringthe Jurassic, obduction was limited to the wedge comprises the Barremian to earliest Albian (middle Omineca Belt and deformationhad yet to extend eastward Cretaceous) Bullhead Group (Thompson, 1989) and may to the Foreland Belt. Continued eastward impingement of correspond to D, deformation. the Quesnel arc led to further compression along the west- Upper crustal rocks cooled immediately after Middle ern edge of North America. Due to the size of thearc Jurassic metamorphism. Lower parts of the thickened pile system, extensive eastward obduction (as with the rela- remainedat considerable depth and experienced partial tively thin sheets of Slide Mountain ocean-floor material) melting leading to the formation of granitic plutons, such wasnot possible. Instead, the Quesnel arc was wedged as the Germansenbatholith. and associated vein and againstthe thicker part of thedeformed miogeocline porphyry-style prospects in rocks of the Takla and Nina (Price, 1986; Figure 67h). This wedging led to the forma- Creek groups. tion of D, structures. In this model, structures in the upper pat of the wedge are antithetic to the motion within the LATE CRETACEOUS TO EARLY TERTIARY entire deforming pile (i.e.,southwesterly directed fold and The youngest period of deformation recorded in the fault structures seen all along the western margin of the map area is right-lateral motion on the Manson fault zone, Omineca Belt). In the lower parts of the wedge, synthetic concurrent with upliftof the Wolverine metamorphic core- D, structures predominate. The presence of antithetic D, complex along the Wolverine fault zone (Figure 67h). The structures in the MansonCreek area may indicate its Manson fault zone is one of many right-lateral fault sys- position in the lower partof the wedge. Alternatively, this tems that were active along the length of the Canadian mayalso be explained by obductionwithout wedging. Cordillera during Cretaceous and Tertiary time (Gabrielse, Theage of D, (wedging)deformation is Middle 1985). Oldest strike-slip motionis at least as old as earliest Jurassic,as inferred from thepresence of metamorphic Late Cretaceous as a strand of the Manson fault zone is micas growing along S, cleavage planes in the Boulder plugged by the 106 Ma Germansen batholith. An Early Creek group. In the Ingenika Group, D, deformation out- Tertiary upper age limit for motion on the Manson fault lasted metamorphism which suggests thatit may he youn- zone is based on the age of the Uslika basin, which may he ger than Middle Jurassic. Southwest-directed deformation a negative flower structure at the northern termination of in the southern and northern Cordillera is Middle Jurassic the fault. in age (Brown ef a/., 1986; Bellefontaine, 1990). Polymetallicveins are the most common mineral occurrences within the map area. They are spatially related EARLY TO MIDDLE CRETACEOUS to the Manson fault zone and to strongly altered ultramafic bodies that crop out along the fault. Movement along the Metamorphosedrocks of the Omineca Belt were Mansonfault zone led to thedissection of previously broadlywarped and uplifted subsequent to ohduction- obducted sheets of the Manson Lakes ultramafics. Fluid relatedtectonism. This resulted in thedevelopment of migration along the Manson fault system undoubtedly led regional-scale,postmetamorphic anticlinoria (Wolverine to thealteration of thesebodies. A 134 MaK-Ar age antiform; D,) that are found along the northern part of the obtainedfrom mariposite from an ultramafic body near Omineca Belt. This deformation may be related to con- MansonCreek may recordalteration related to earliest tinued accretion of allocbthonous rocks to the west. motion on the Manson fault zoneor may he a reset partial The age of D, deformation is not well constrained record of alteration during obduction or even during the within the map area. It must range from Late Jurassic to suggested Permian basin collapse. Early collisional defor- possiblyLate Cretaceous time. This corresponds to the mation events must have produced numerous shear zones period between the endof D, deformation and the onsetof which, in conjunction with those produced during motion extensional tectonism in the Omineca Belt. Metamorphic onthe Manson fault zone, may have facilitated fluid cooling ages within large postmetamorphic antiforms sug- migration driven by high heat-flow from the Wolverine gest D, deformation occurred between Early and middle Metamorphic Complex. Cretaceous time (Evenchick, 1988). Wide reaching effects Uplift of the Wolverine Metamorphic Complex began of D, deformation are preserved in the stratigraphic record in Late Cretaceous time, culminating in the Early Tertiary. Thlls is well documented by K-Ar metamorphic cooling metamorphic grade on each side of the fault indicate that ages within thecomplex (Appendix 11, Figure57). A motion has decreased and mapping by Gabrielse (1975) singleexception is the LateCretaceous date from the andRoots (1954) immediately north of themap area nolthern part of the Wolverine fault zone. indicates that the fault is no longer present. A single apatite fission-track analysis indicates cool- The reason for rapid uplift of the metamorphic com- ing below l00OC at approximately 48Ma. Considering plex is uncertain. It may have been related to instability of that K-Ar blocking temperatures of metamorphic minerals the thickened crust following cessation of compressional require that they passed through approximately 400°C at deformation (Brownand Cam, 1990) or to transcurrent ahout 50 to60 Ma, rapid uplift of the complex is required motion along the Canadian Cordillera (Evenchick, 1988: in the Early Tertiary to explain the up to I00"C per million Struik, 1988~).In thenorthern Omineca Belt detailed years cooling profile. This is supported by the presence of work by Evenchick (1988) demonstrates the relationship metamorphic detritus in the Late Cretaceous to Early Ter- betweenuplift and transcurrent motion. Furthermore, in tiary Uslika and Sifton basins. the northern Cordillera, transcurrent fault systems usually bound portions of core complexes. Motion on these faults Uplift of the Wolverine Complex led to the develop- is contemporaneous with core complex uplift suggesting a me:nt of the Wolverine fault zone, a moderately dipping, genetic relationship. layer-parallel ductile shear zone with dip-slip motion. In Igneous and sedimentary rocks in the lower the southern part of the map area it is overprinted by a parts of the Wolverine Complex were subjected to steeply dipping, brittle shear zone which juxtaposes rela- upper amphibolite grade metamorphism which led to partial melting tively unmetamorphosed, higher level rocks of the Nina andthe production of significantquantities of granitic Cr,:ek group against sillimanite-grade rocks of the meta- magma. Some or all of this magma may also have been morphic complex. The high-level, brittle faults were con- produced by sudden decompression of these rocks during current with and may have passed into ductile motion in the rapid rise of the Wolverine Complex. Most magmatic the lower crust.As lower level, ductile zoneswere uplifted material thus was confinedto the Wolverine andcooled, they were overprinted by brittle fault generated Complex, but amounts of monzonite structures. significant and quartz monzonite of slightly younger age intrude the surrounding In the northern part of the study area offset on the rocks.Some of the Wolverine Range intrusions are Wolverine fault zonedecreases as it cuts down-section alkaline andcontain significant amounts of rare earth into rocks of the Swannell Formation. Rocks of similar elements.

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(1979): Diamond Drilling Report Cordillera: GeologicalSurvey of Canada.Paper 87-15, onthe Lonniemitch Claims, Manson Creek Area; B.C. StNik,L.C. (1988a): SlNcIurd Geologyof the Cariboo Gold Ministry of Energy, Mines and PetroleumResources, Mining District, East-central British Columbia; Geological Assessment Repon 75 15. Survey of Canada, Memoir 421 Wanless, R.K., Stevens. R.D., Lachance, G.R. and Delabio, R.N. Struik. L.C. (1988b): Regional Imbrication within Quesnel Ter- (1979): Age Determinations and Geological Studies, K-AI rane. Central British Columbia, as Suggested by Conodont lsotopic Ages, Repon 14; Geological Survey of Canada. Ages;Canadian Journal of Earth Sciences, Volume 25, Paper 79-2. pages1608-1617. StNik, L.C. (1988~):Exploring the Parsnip: MiningReview, Watkins, J. I. and Atkinson, M. (1985): Report of Evaluation - Volume 8, pages 66-68. Nina I MineralClaim, Omineca Mining Division; B.C. Ministry of Energy.Miner and PetroleumResources. StNik, L.C.(1989a): Devonian, Silurian, Cambrian and Pre- Assessment Repon 13 977 Cambrian Stratigraphy, McLecd Lake Map Area, British Columbia; in Current Research, Pan A, Geological Survey Wheeler, J.O. and McFeely, P. (1991): Tectonic Assemblage Map ofCanada, Paper 89-IA. pages 119-124. of the Canadian Cordillera and AdjacentPans of the United StNik, L.C.(1989b): Regional Geology of theMcLeod Lake States of America:Geological Surve? of Canada. Map Map Area, British Columbia; in Current Research, Pan A, 1712A. Scale 1:2 ON ON. GeologicalSurvey of Canada. Paper 89-IA.pages Winchester, I.A. and Floyd, P.A. (1976): Geochemical Magma 109-114. TypeDiscrimination: Application to Altered and Meta- Struik, L.C. (1990): Stratigraphic Setting of Late Paleozoic and morphosed Basic Igneous Rocks; Earth and Planetary Sci- Mesozoic Fossils, MacGregor Plateau, Mckod Lake Map ence Letters, Volume 28, pages 459-469. Area, in CurrentResearch, Pan A,British Columbia; Geological Survey of Canada, Paper 90-l A, pages 55-64. Winkler,H.G.F. (1979): Petrogenesisof Metamorphic Rocks; Springer-Verlag, New York. Struik, L.C. and Fuller, E.A. (1988): Preliminary Repon on the Geology of McLeod Lake Area, British Columbia; in Cur- Woodcock, N.H. and Fischer, M. (1986): Strike-slip Duplexes; rent Research, Pan A, Geological Survey ofconado, Paper Journal of Structural Geology, Volume 8, No. 7, pages 88-1E, pages 39-42. 725-735. APPENDICES .".-.,,.1v 1 wrmwm1 MICRO AND MACROFOSSIL AGE DETERMINATIONS

Map MapUnit FieldNumber GSC bating Northing Forsil, Tam CAI & Lee (LitholopJ) (Sampler) Number (Number OlSpechnew) Wellslwks) Rob.bly F, IngcnikaGmp FF87-51-4 C-I53780 414230 6168100 condom prnoconodoDt (1) ds Fiuncmmic, x.mbriml (Carbonate) (F. Feni)

Fz AmGmp FFe89-28-2 6215754 sponges384535 C-168387spicvles da phurroeoie (C") (C") (F. Fmi) 3841546218230 II archacacyathids archaea'yalhids. scvdgem

- Fs EchoLakcgroup FFe89-742 C-168365 - (CarbOMte) (F. Feni)

Echo Mepp FFe89-33-3 C-168390 (e-*) (F. Feni)

381890 6218250 grnproliteJ6218250 381890 MomgmptuJspp.l2) da silllrian (pwh.pa LIandO"aian)2 (shale) (D. Melville) ?Pristogmptw sp. ktiolitid graptolite

~~ ~~~ Otter Lakes pup FFe89-23-17C-168385 6218272375978 conodonts Eelodclk~sp. (8) 6 Early-Middle Dcvooianl (carbonate) (F. Fem) Pondorinrllinosp. (4) &form elements (2)

(carbonste) (F. Feni)

(CarbOMIC) (F. Feni) - - - ,154398 18348 Irn5

i - i ,161988386251 t 106521

- 37898 386620 106550 - -153791409464 71645 Morovian)] - ,154380394045 85991 - ,454381391629 92729 - ,154383396180 91635 - ,167977382717 100386 - ,167916383535 100707 - ,167973386497 104076 - t+,168400382655 1ooo88 ii Fu NinaCreekgrwp FFe89-21-12-1C-168380 3853566211648 (chert) (F. Ferri)

FU NinaCreek group JHW89-34 C-167968317711 6212260 (then) (1.H. Wttles)

Fzs NinaCreckgmup FFe89-24.7 C-167983 3809036213307 conodonts Ncogondoldo6-7 sp. (3) Pennianl (chert) (F. Fem) ramifm elements (5)

F2, NinaCreckgmup FFe89-21-12-2 C-I67981 385356 6211648 conodonts Ncogondolch sp. (3) 5 Pennianl (Chi) (F. Ferri) ramifom elements (5)

FZa NinaCreekgroup FFe89-20-6-2 C-I68379 3836336212102 conodonts Neogondolclla sp. (1) 6.5-7 Pamian1 (chert) (F. Fem) ramifom elements (I)

.. (chert) (D.Melville) sphamnwrp hs

Fp CreekNina group FFc92-37-9-1C-208306 379260 6220280 conodonts ramifom elements (3) 5 Early csrbonifcrousl GMlhodus sp. (4)

conodonts Ellisonio sp. (2) Permian-Early5 Middle Triassicl limestone (D. Melville) Neogonddello sp. (6) Hindrodus? sp. (I)

F32 Evans CreekDMe88-30-2-1 C-154375 3163736188431 conodonts Melopolygmlhw sp. (I) Limestone (D. Melville) sphamnwrp hs II

F, EvansCreek RAR88-7-3-1C-154371 385021 6182878 conodonts NcogondolellaMiddle 5-6 sp. (2) to Late hian1 limestone (R Arksey)

Evans Creek DMe88-30-2aF35Creek6188558 C-154396316341Evans conodonts Neogondolclla sp. (3) 5 Middle-LateTriassic(Ladinian- limestone (D.Melville) CamiM)l Map MapUnit FieldNumber GSC Wing Narthiog Fwsils Taxa CAI b Loe (Lithology) (Sampler) Number (Number of Specimens) (Remarks)

F36 Evans Creek 376347 C-1543946188558 conodontsDMe88-30-2b BudurovigMlhw ? sp. (1) 4.5-5 Late Triassic Camian; Early TriassicI limestone Meropolygmhw spp. (9) (D. Melville) (Ncosporhodussp. is onomnlow, Neospnrhodw cf. N. dieneri (Sweet)(I) presumably reworked)

Evans CreekDMe88-30-2d (2-154395 376347 618855 conodonts MeIapoIygmlhur sp. (I) limestone (D. Melville)limestone (D. IIII I 1 F38 Evans Creek DMe88-30-2c C-154393 376347 conodonts 6188558Neogondoklla ex gr. comlriclo (Mosha & Clark) (8) 4.5- Middle Triassic(late Anisian-ly limestone (D. Melville) ramifom elements (I) 5.5 Ladinian)l

F,, TaklaGmup C-153782 421720FF87-50-6 conodonts 6154450Nmgondolellasp. indet. (4) 5-55 MiddleUte Triassic (Mnian to (Carba"tlte) (F. Ferri) Camian)l

F40 TaklaGmup 403705 C-154364 conodontsDMe88-4-9-1 6168728ramifamelements (1) 5 Ordovician to Triassic1 (carbanate) (D. Melville)

~ Meropolygmthwsp. (2) LateTriassic Camianl (carbonate) 15 I 1 - IM. 1. Orchard, Cordilleran Division, Geological Surveyof Canada. Vancouver, B. C. P 2B. S. Norford, Paleontology Subdivision, Instituteof Sedimentary and Pemleum Geology. Geological Survey of Canada, Calgary,Alberta. 311. Ludvigsen, Denman Institute for Research on Trilobites, 4062 Wren Rd.. Denman Is, B.C. 4Ross and Monger (1978) 5B. Mauer. Cominco Exploration Ltd.,Vancouver, B.C. CAI = Conodont Alteration Index. n/a = not available or not applicable APPENDIX I1 GEOCHRONOLOGY FOR ROCKS INTHE MANSON RIVER MAP AREA (93N/09 and 15)

U-Pb DATA large amounts of common lead, or that the fractions were Rocks from the Wolverine Complex,Wolf Ridge gab- contaminated with either pyrite or feldspar. Unfortunately bro and Big Creek group, in the Manson Lake area, were there was insufficient zircon available to repeat the analysis. dated by U-Pb methods. The analytical data are listed in This date is not precise, but gives an indication of the ap- Table 7. proximate stratigraphic age of the unit.

FF87-34-2. DaciteTuff FF87-37-7, Wolverine Complex Granodiorite Zircons separated from this dacite tuff were clear, The zircons extracted were clear and colourless, euhe- nearly colourless to light brown, doubly terminated square dral to subhedral acicular doubly terminated prisms. About sectioned prisms with aspect ratio 1:1-3. About 10% of the 30% were fragments, and a few had cloudy, radiation-dam- crystals were dark and opaque; these were avoided. Six frac-aged cores. The best, clearestcrystals werechosenforanaly- tions were air abraded, and the finest fraction was left intactsis. Oneof the zircon fractions was abraded. The monazites to obtain a measure of lead loss. Acicular crystals with as- were.. clear, bright yellow,blocky, subhedral grains. pea: ratio1:4-6 were picked from the intermediate magnetic TWO of the zircon fractions are strongly discordant. and fraction. Cloudy cores were visible in20% of the crystals; are interpreted to contain inherited zircon. An analysis of these were avoided in picked fractions. the fine magnetic zircon fraction lies on concordia at about The fractions analysed yield a patternof combined lead 71 Ma. Although the three zircon fractions donot fall on a loss and inheritance, as shown on the concordia plotin Fig- single discordia line, they can be used to define limits on the ure 68. All fractions lie below concordia, butdo not lie on a age of this rock. The average ageof the inherited zircon is single discordia line. The four coarsest abraded fractions 1.8f0.1 Ga (upper intercept of a two point regression give a strong indicationof inherited old zircon with an av- through fractions b and c. The minimum ageof intrusion is erage ageof 2.4H.01 (2a)Ga. Fractions b, c and d are less derived from the lower intercept of this regression (Figure discordant but fall below the discordia line, thus indicating 70), at 71.0&0.6 (20) Ma. TWO fractions of monazite were lead loss from the zircons.If these fine zircons have lost lead analysed; they lie above concordia indicating the presence of excess 2ffiPb resultin from 23% disequilibrium (Par- then the coarse ones may also have doneso. Thus the lower 935 intercept of the three-point discordia line through the coarserish. 1990).The 207Ph/ U age is the most reliable for fractions defines the lower limit for the age of the rock, monazite analyses; the meanof fractions e and fis 72.8f0.2 377+12 (2a) Ma. Since a rock should not be significantly Ma, which is the same, within error, as the zircon age, and older thanthe 207Pb/206Pbdate of the most concordant frac-is considered to represent the intrusive ageof the rock. The tion. the upper limit on the age is 533k7 Ma, from fraction mean age is 72.6H.2 Ma. d. Further analyses are requiredto define the ageof the rock more precisely. CONCLUSIONS The interpreted results of U-Pb zircon dating of three FF87-4-4-1, Wolf Ridge Gabbro samples in this area are as follows: This gabbro yielded very few zircons,of whichall were The oldest rock is the dacite tuff from the Big Creek relatively magnetic. The zircons extracted were mostly frag- group, which gives a minimum age of 377f12 Ma ments of euhedral to subhedral, doubly terminated prisms. (2a) with lead loss, and inherited old zircon of average age They were clear and colourless, although some were stained 2.4kO.01 Ga. by iron. All the zircons were usedin the three analyses, di- The date from the Wolf Ridge gabbro is of poor quality vided by size becauseof the small amountof available ma- because of lack of material available, and is tentatively terial. They were not abraded prior to dissolution. placed at a minimumof245 f0.7(20) Ma, based on three The fractions are plotted on a concordia diagramin Fig- fractions. ure 69. The age of this rock is not well definedby the three The youngest of the three rocks is the Wolverine Complex analyses. Fraction a is relatively imprecise, is but essentially granodiorite, at 72.6? 0.2 Ma. concordant. A minimum age for the rock is given by the 206Pb/238Udate for this coarse fraction, 245.4k0.7 Ma (20 ANALYTICAL METHODS error), as listedin Table 7. Fractions b and c appear to have Zircons and monazite are separated from finely crushed lost lead. 10 to 40-kilogram rock samples usinga wet shaking table, The three fractions have low uranium and lead contentsheavy liquids, and magnetic separator. The heavy mineral (Talble 7). and low measured 206Pb/2MPb ratios (under concentrates of samples FF87-34-2 and FF87-4-4-1 were 1000 These two factors increase the analytical errors. The washed in approximately 3N nitric acid for half an hour below "Pb?"Pb ratios suggest that the zircons contained fore separation lo remove rust and someof the pyrite. The 0.04 .

3 3

upper inl.rc.pl 2.43 +/-0.01 Go

m1nlm"m09. 377.3 +/- 12 u.a 3-pt. rqnsslon (f-p-h) 245.4 +/- 0.7 Ua mlnlm~mage -207/206Pb 00. 01 II 0.0 . I 0.02 v 0.15 0.20 0.25 0. 0.0 1 .o 2.0 3.0 4.0 5.0 207pb/235 207pb/23S u

Figure 68. U-Pb concordia plot for Gilliland tuff. The fractions Figure 69. U-Pb concordiaplot for Wolf Ridge gabbro. The are labeled as in Table 7. Error envelopes are given at the 2u fractions are laheled as in Table 7. Error envelopes are given at level. the 20 level.

Zircon age 71.0 +/- 0.6 Ma Uonazite 207/235 oge 72.8 +/- 0.9 Uo Mean 72.6 +/- 0.2 Ma

0.009 0.06 0.08 0.1 207pb/235u

Figure 70. U-Ph concordiaplot for WolverineRange granodiorite. The fractions are labeledas in Table 7. Eror envelopes are given at the 20. level. TABLE 7 ti-PB DATA FOR SELECTED VOLCANIC AND IGNEOUS ROCKS IN THE MAP AREA.

a NM1.8A/Io 1.0 0.09323(,179)284111.9 28.1 276 1.3869(.201) o.107~9(.061) +134pm abr 574.612.0 883.4i2.2 1764.M2.2 b M1.8N1° 0.05330(.113)2864 7.5 35.5 670 0.30 0.4360(.130) 0.05933(.046) -44pm 334.8i0.7 367.4i0.8 579.1*2.0 c M1.5N3" 27.6450 0.60 8.4 0.06028(1.36)2546 0.5764(1.37) 0.06936(.089) -74+44pm abr 377.3+10.0 462.1*10.2 909.3i3.7 d M1.8Nlo 0.10 9.830.8 638 0.04642(.085)877 0.3717(.223) o.o~so~(.168) -74+44pm abr 292.5*0.5 320.9*1.2 532.517.4 f NM1.8NIQ 0.059 182 48.6 0.23563(.060)782713.1 4.609(.097) 0.14188(.046) +149pm abr 1363.9*1.5 1751.0*1.6 2250.3*1.6 g NM1.8NLO 0.062 245 51.4 0.19324(.047)9387 9.9 3.622(.051) 0.13594(.018) +149pm abr 1138.9*1.0 1554.4*0.8 2176.2k0.6 h Nh41.8NIo 0.046 231 27.8 40.9 30750.07630(.103) 0.8287(.133) 0.07877(.081) -104+74um abr 474.0i0.9 612.9*1.2 1166.3i3.2

FF87-4-4-1 Wolf Ridge Gabbro a M1.5N3' 0.03880(.140)316 12.51.75 43.6 0.20 0.2718(1.04) 0.05082(.978) +74pm 245.4i0.7 244.2i4.5 233i46 b Ml.5N3" 61.00.30 2.08 12.1 0.03271(,127)367 0.2307(.807) 0.05115(.746) -74pm 207.5i0.5 210.8i3.1 247i35 c bulk 92.10.020 2.82 18.4 8s 0.02395(.364) 0.1714(3.33) 0.05191(3.13) 152.6k1.1 160.6i9.9 282*150 l'F87-37-7 Wolverine Complex Granodiorite FI NM2NI0 0.6 23.62281 5.9 0.01055(.176)1576 0.0829(.222) 0.05700(. 107) -149+74pm 67.7i0.2 80.910.3 491.4*4.7 tl M2AlI" 0.10 3430 39.6 5.0 xo70 o.o1209(.165) 0.0883(. 185) 0.05300(.056) +74pn1 77.410.3 85.9+0.3 328.6*2.6 c M1.5N3° 0.3 3803 177 78.2 77x o.oIIo~(.~)o.n725(.556) 0.04741(.337) -74pm abr 71.li0.5 71.0i0.8 70i16 I: monazite 0.057 2093 208 88.9 0.01157(.239)632 0.0739(.396) 0.04633(.259) 74.2i0.4 72.410.6 14.9i12.5 1- monazite 28339830.09 85.2 1954 0.01148(.073) 0.0744(.147) 0.04700(.099) 7 3.6hO.l 72.k30.273.6hO.l 49.3*4.7 'Notes:.- Analyses by J.E. Gabites, 1989- 93, in the geochronology laboratory, Department of Geological Sciences, U.B.C.. IUGS conventional decay constants (Steiger and IBger. 1977) are: 238Uh=l,55125s10"0a". 235Uh=9.8485s10-ioa", ?38U/235U=13788 aton1 ratio. I. Column one gives the label used in the Figures. 2. Zircon fractions are labelled according to magneticsusceptibility and size. NM = nonmagnetic at given amperes on magnetic separator, M = magnetic. Side slope is given ill degrees. The - indicates zircons are smaller than, + large1 than the stated mesh (p). Abr = air abraded. 3. U and Pb concentrations in mineral are corrected for blank U and Pb. Isotopic compositionof Pb blank is 206:207:208:204 = 17.299:15.22:35.673:1.00,based on ongoing analyses of total procedural blanks of 37*I pg (Pb) and 6 f 0.5 pg (U) during the time of this study. 4. Initial common Pb is assumed to be Stacey and Kramers (1975) model Pb at the207Pb/Z06Pb age for each fraction. TABLE 8 APPARENT AGEAND TRACK LENGTHS FROM APATITE GRAINS IN SELECTED SAMPLES FROM THE LOWER INGENIKA GROUP

Sam ple Apparent Age(Ma)Apparent Sample UraniumLength(pm)Track Number(Number of Grains) (ppm) (Number of Tracks) m7-38-4 k3.5 48.3 29 13.3 k1.6 (20) (76)

DM 87-31-12 42.4 k3.4 22 k3.4 42.4DM87-31-12 12.4 d.9 (13) (30) Samples were analyzed and modeledby D.S. Miller of Rensselaer Polytechnic Institute. 1989. Model based on zeta method using standard apatites from Fish Canyon tuff, Durango (Laslett et al., (1987) and Green (1988). Questions concerning analytical techniques and modeling should be addressedDr. toMiller. la standard deviation. See Figure 58 for location of samplem7-38-4

120

1 00

tT Plot for OM 67-31-12 (SO Irosks)

04 . , , , , , , , , , , , ~ , . I I I 0 10 20 SO 40 50 60 70 80 0 20 40 60 0 ACE (No) ACE (No) Figure 71. Apatite fission-track cooling curve history for sample Figure 72. Apatite fission-track cooling curve history for sample FF87-38-4from within high-grade rocks of the lower Ingenika DM87-31-12from within high-grade rocks of the lower Ingenika Group. Pertinent data are shown in Table 8. Group. Pertinent data are shown in Table 8.

TABLE 9 K-AIANALYTlCAL DATA

RM m MlNERU I( a'& amI AGE NUUBER 2?!!?tL (*I wwm) 0(UlJ DMB7-X-3 61W01 1.96 4.0.02 2.7 78.1 so.7 4.1.8 FF87-154 616- 8.32 4 0.03 U.965 95.1 13445 FFe7.1W 6159583 4.22 4.0.02 5.408 46.1 92.7++12 FF67.22.1 81m 6.87 4.0.06 13.104 872 48.64.1.7 FFE88.21-1 6166366 4.80 4-0.05 9.913 90.2 524 41.8 FFEw3e-10 621m 8.45 4-0.01 12247 04.9 482 4. 1.7 FFEBp3b17 6215476 723 4.0.06 16.Lyu) 90.1 59.1 4.2.1 FFE8P38-16 621635 0.70s 4-0.011 4.85 958 171 4.9 FFE8sss1 (n1333p 1.45 4. 0.03 24331 95.6 62.3 4 2.8 GMB7.124 6153356 7.104. 0.07 a.187 po.l 106U.4 GME7-0-1 6174775 8.W 4. 0.m 15.737 __70.9 49.5 4. 1.7

I18 concentrates are split into magnetic (M) and nonmagnetic The decay constantsare those recommended by the IUGS (NM) fractions, sized using new nylon mesh screens. and Subcommission on Geochronology (Steiger and Jgger. hand picked to 100% purity. Concordance is improved by 1977). Concordia intercepts are calculated using a modified air abrasion techniques (Krogh, 1982). Chemical dissolu- York-Il regression model (Parrish eta[., 1987) and Ludwig tion andmass spectrometry proceduresare modified sli htly (1980) error algorithm. Errors reported for the raw U-Pb from those of Parrishef nl., (1987). A mixedzosPb-2 5- 'U data are one sigma; those for final dates and shown on con- 235U spike is used (Parrish and Krogh, 1987; Rcddicketal.,cordia plots are two sigma (95% confidence limits). 1987). The dissolution is in small-volume teflon capsules contajned in a large Parr bomb (Parrish, 1987). Both ura- APATITE FISSION-TRACK nium and lead are run on the same Re filament with silica gel and phosphoric acid. Lead isrun first at 1250-13000C, The following account was provided by Donald S. Institute) whoper- then the uranium at 1350-1400°C. ADaly collector is used Miller(Geology,RensselaerPolytechnic to improve the quality of measurement of low-intensity formed the analyses on these samples. ZMPlbsignals. The error propogation techniqueof Roddick These two samples do not seem to have very similar e? al. (1987) is usedto calculate errors associated with indi- cooling histories, however,with only 30 tracks suitable for vidu,al analyses. The laboratory blank has an isotopic com- track length measurementwe have little faith in the thermal posil.ion: Pb 206207:208:204= 17.299:15.22:35.673:1.M). history plot for DM87-31-12 and thus discount it com- Current laboratory blanks for uranium and lead are approxi-pletely. The cooling history for FF87-38-4 seemsto be very mate:ly 6 f 0.5 and 37 f 0.4 picograms respectively, based similar to SDU88-15-11.We are somewhat perplexedby the on ongoing analyses of total procedural blanks. A larger young K-AI ages on biotite which indicate temperatures in valuo maybe used in data reduction to correct for unusuallythe rangeof 2WOC at 40 Ma while the apatite tracks start to large amounts of common lead incorporated into some frac-be retained at 45 to 50 Ma (requiring temperatures below tions:. The isotopic composition of commonlead is based on IooOC)! The hornblende data of 512 Ma suggest that the the Stacey and Kramers (1975) common lead growth curve,cooling from approximately500'C to 1WOC occurred very and is takenat the age of the207Pb/206Pb age of the fraction. rapidly, perhaps over a periodof a few million years.

1 I9 APPENDIX 111 Sample localion maps and data tables for whole-rock and trace element data Manson Creek area. Figures Xa, b and c correspond to the area covered by the geology map in the pocket at thc hack of this repon.

LEGEND x -Whole Rock and Trace elsmenl lithogeochemirtry sompie file -Lllhogeochemlrtry of mineralized and non-minsrolized rockr. aompie sile

A -Stream and mo$r-mot geochemistry somple rlle 0 -1983 Regionol gsochemicoi rtreom sediment sompla site * -Bulk. moss-mal andstream redimenl geochemicrtry Sample numbers refer la lirllngr in oppsndlces Dl ond IX

121 .

L I -d

h c

Figure 8b LEGEND x -Whole Rock and Troca element Iithogsochemlrlrysample rile * -Lithogeochemistry of minemiiredand "on-mineralized rocks. rampierite . -Sireamand mors-mal geochemislry sample rile b -1983 Regional geochemical dream sediment rampie rile . -Bulk. mors-maland rlream sediment geoshemicdry Sample numbers refer lo lirlingrin appendices IlC and DI

122 Figure 8c. LEGEND x "Whola Rock and Trace elemenl lilhogeochsmirlry sample sile * -Lilhogeochemirtry of mineralized and nom-rnineroiized rocks. sample rile

L -Stream and moss-mal geochemirlry rornple rile 0 -1983 Region01gsochemisol sfreom sediment wrnpie tils - -Bulk. moss-mol ond dream tsdimcnl gsochemicrtry Sample numbers refer lo listings in appendices Ill ond IX

I23 APPENDIX III LIST OF WHOLE-ROCK AND TRACE ELEMENT DATA FOR VARIOUS VOLCANIC AND IGNEOUS ROCKS

Msp GRWP ROCK FIELD mm Si02 TK)z AE-33 Fern MnO MpO c.0 Na20 W P205 LOi SUM Fa Co2 S No. WE NUMBER EaaUnp Nomg % %X% x %X% x x% %X% x W.1 BWW,C& anphibolle WE87-1001 411656 5164738 50.40 1.04 14.82 10.21 0.18 6.80 6.31 2.35 0.03 0.09 6.80 39.05 n. ra m W.2 4e.95 1.43 r8.m 10.07 0.21 5.82 8.95 3.78 0.46 0.18 3.07 99.71 na ra m Wil 6I.94 0.71 15.59 3.30 0.m 0.88 1.41 sa1 2.80 0.15 3.15 99.05 127 1.81 0.81 W4 67.67 0.55 15.20 2.71 0,M 1.21 1.89 1.55 3.54 0.15 4.49 39.m 1s 3.07 0.98 WJ 70.25 0.71 14.88 3.50 0.m 0.83 0.44 1.46 5.71 0.17 2.18 39.92 127 0.75 4.01

Wd G.h Wbm FFEB839.1 381251 8186423 47.04 0.22 14.88 5.m 0.11 953 17.35 123 027 om 4.55 99.08 3.41 2.21 0.10 w-7 Taa7 bad FFE659-1 398275 6175243 50.81 1.50 15.88 10.12 0.17 5.80 8.52 4.15 0.02 0.17 2.88 99.85 M m n. wa Taws7 bUun FFEBBBI-1 398275 6175243 45.37 0.78 12.99 10.41 0.19 9.w 8.88 1.83 0.83 0.11 10.81 93.85 6.31 8.51 4.01 w.9 Nim Cmk basal FFEW-2511 3¶4Wa 818W uI.22 1.36 15.17 10.58 0.16 7.83 9.83 2.36 1.04 0.11 3.38 99.88 5.94 0.15 0.11 w.10 Nlm Cw basal FFEBs29-10 394341 816EdS 49.70 1.81 13.94 11.88 0.21 5.91 10.711 3.15 0.08 0.13 2.88 99.83 8.31 0.18 0.11

W-11 NIM Cmk bd DME874P3 417183 8165516 a.85 1.92 15.57 11.27 0.18 4.92 10.57 3.95 0.17 022 1.82 99.27 "a m n. w-12 NIM Cmk bad ~~~87.1944009188 8171661 a.27 1.88 14.08 1127 0.20 7.02 9.72 3.64 0.07 0.17 3.19 99.35 "8 m n. W-13 Taws? bad FFE853-6 401902 6172291 a.37 0.87 17.m 10.08 0.19 5.29 8.98 3.62 2.47 0.15 4.52 39.55 4.97 1.85 4.01 W-14 Taws? hl FFEBW-10 398739 6173983 42.12 0.56 13.21 7.w 0.14 8.19 13.08 1.80 1.82 0.14 13.76 1m.m 853 10.1 4.01 W-15 Nim CmkIMlpllut.1 basal FFE68.35-1 391381 619U394 51.91 1.53 13.83 11.35 0.20 5.83 9m 3.09 0.35 0.13 2.88 99.88 6.95 0.48 4.01

w-16 NiM Cmk basal FF-1 391361 819U394 51.88 1.53 13.61 11.39 0.20 5.67 924 3.11 0.24 0.13 2.88 99.98 6.17 0.43 4.01 - w.17 Nim Cmk bd FFE8837-1 390625 6193282 51.33 1.57 13.99 1125 0.19 8.04 a82 4.25 0.08 0.13 2.47 1m.io 6.1~ 021 4.01 K W.16 Nim Cmk bUul FFEBM14 388299 6191518 50.80 1.76 14.08 11.81 0.20 6.35 9.50 3.77 0.08 0.17 1.98 1m.w 8.52 0.29 0.01 w.19 NImCwk basal FFEWI 395356 8183739 49.30 1.30 14.78 10.49 0.17 7.66 9.42 2.W 0.67 0.10 3.05 99.84 6.55 0.W 0.03 w-20 Nim CW basal FFE8M-10 385919 6203446 48.76 1.49 14.04 10.72 0.16 6.22 12.60 2.59 0.03 0.15 2.97 99.73 7.28 4.14 4.01

w-21 NIm CRek baMl FFE6018.00 378180 8203188 uI.61 1.31 14.40 10.83 0.17 7.20 10.31 3.39 0.08 0.11 3.15 99.39 8.75 4.14 0.08 W.22 Nim CRek bd FFE6941-14 376722 6195385 50.56 1.21 18.08 10.27 0.16 5.26 I.55 4.93 0.20 0.10 2.89 mzz 6.75 4.14 0.05 wm BuL.L. Vdcanks basan FFE69.5C-3 40W 6193793 49.57 1.33 18.18 10.17 0.15 5.88 I.61 4.03 2.08 0.85 1.23 99.35 n. m m w.24 NIm Crrk pbbm DME87.151-1 417769 6159455 uI.76 0.5 16.14 7.56 0.14 7.51 11.18 1.38 0.8 0.01 5.91 99.83 4.39 0.14 4.01 W-25 NIra Cmk pbbm DME67.1514 4155m 61615M a.21 0.42 15.95 6.84 0.13 7.44 11.07 1.75 0.33 0.m 6.88 39.85 4.13 0.55 0.02

W.28 Nim Cmk wbm FFE87-7-2 420138 6162824 55.20 2.18 14.16 12.11 0.23 211 4.42 8.88 0.21 0.39 1 .85 99.56 ne m n. W-27 NIM CmM:oupliae) wbm FFE87.29.1 419877 8157562 a.44 1.83 15.08 5.88 0.12 6.56 17.45 1.82 0.2 0.17 2.74 1m.23 4.45 0.07 0.02 W-28 NIm CRek Wbm ~~~87.2~1419877 6157582 47.37 1.95 15.m 8.08 0.12 6.56 16.80 1.97 0.21 0.21 2.95 99.49 na M na W-29 Nim CRek bad FFEW2-7 398315 8162367 s0.P 1.85 15.Y) 11.47 0.23 5.66 6.93 3.66 0.21 0.15 2.47 99.91 6.45 0.15 4.01 W30 Nloa Cmk mal1 DME69.156 379941 6202879 47.39 1.56 13.46 12.32 0.20 7.94 9.43 3.49 0.07 0.13 3.04 99.15 9.13 4.14 0.10

Will Nim CRek basal DME69.1&9 377388 6207814 49.38 1.47 13.80 10.45 0.19 5.87 14.m 0.78 0.w 0.14 3.56 99.73 6.75 4.14 4.01 W32 NIm Cmk Wbm DMES~.I%~O 416089 SIBMU 49.13 1.43 16.42 10.45 0.23 5.72 9.35 3.48 0.43 0.12 2.93 99.87 8.16 0.07 4.01 W33 NimCmk Wbm OME67-1311 4159126165595 48.92 1.u 14.99 10.45 0.18 8.63 8.88 3.20 0.81 0.14 3.10 98.80 M m n. W-31 Nim Creek Wbm 0~~874s-10 4180~ e.1~20 4e.P 1.23 14.32 10.14 0.17 7.63 11.21 2.94 0.20 0.12 3.16 99.83 n. m n. W-35 Nlm Cmk Wbm FFEQM31 403211 6181950 80.m 0.67 15.31 9.81 0.19 1.13 4.45 5.22 0.41 0.28 2.27 1m.m 1.20 0.15 4.01 W38 NimCmk gabbm OME8M-7 390898 6196581 47.14 1.32 15.95 10.00 0.17 6.60 10.73 3.28 008 0.12 3.60 99.07 7.40 4.14 4.01 W-37 Nim Cmk basal WE89.154 379314 8211280 49.14 1.78 15.14 11.49 0.17 7.15 7.12 3.54 0.43 0.18 3.08 99.20 6.89 4.14 4.01 WJB Nlm cR.k paWm FFE548.5 386388 W93 47.14 1.27 11.57 10.92 0.20 11.20 11.56 1.54 0.98 0.11 3.05 99.52 6.80 4.14 4.01

WJB Nim Creek mbbm FFE648.7 388093 8203782~ ~~ 50.23 1.55 14.32 10.79 0.16 8.98 7.94 4.23 0.28 0.14 2.87 9927 6.41 4.14 4.01 W4 Nlm CRek basal FFE801506 W117 6198141. . 49.10 1.56 12.85 11.59 0.20 7.40 11.99 1.77 024 0.13 3.28 99.91 7.55 4.14 0.10 Map GROUP ROCK FEW UTM UTM SiU2 Ti02 NZCQ Fe203 MnO MpO C.0 NaZO Km P205 LO1 SUM F.0C02 s rYPE NUMBER Eaating Naming % % % % %% % % % % %% % w:l ~~ ~ - ~ .~ - 2 x ~ ~ ~~~ ~~~~ ~~ ~ ~~~ - Wd1 Nim Creek pbbm FFE0P.lM)S 383513 6200840 48.83 1.01 15.08 9.58 0.17 7.13 11.59 2.13 0.04 0.06 4.11 99.81 7.26 4.14 4.01 WU Nim Creek pbbm FFEBP.Z@IP 6212444 46.12 2.88 12.- 16.oJ 0.25 5.27 9.43 2.70 0.41 0.14 3.35 99.24 0.12 4.14 0.02 WU Nim Creek Wbm FFE0P23.27 378089 6217301 48.91 1 .m 13.93 9.74 0.20 8.47 11.04 2.58 0.71 0.09 2.72 99.40 7.69 4.14 4.01 wu NirU Creek pbbm FFE0P.2412 380816 6214157 49.40 1.65 14.11 10.50 0.21 0.53 10.40 3.41 0.11 0.15 2.74 9929 8.34 032 4.01 Wd5 Nim CrSeYDUpliIe) pbbm FFEBO.2412C380816 6214167 49.20 1.65 14.11 10.58 0.20 8.48 10.39 3.41 0.12 0.14 2.73 99.09 0.20 4.14 4.01

Wd0 gebbm FFE8S-22k17 381971 6215827 47.74 1.71 14.10 11.7< 0.20 7.45 10.35 3.38 0.02 0.13 2.91 99.76 0.91 0.28 4.01 w.47 pbbm WH80E-S 380165 6217169 48.33 1.79 13.89 11.65 o.n 7.12 10.14 3.22 0.01 0.17 2.82 99.30 0.77 0.43 4.01 WdO unmmc mn~o3.7 377001 6212518 36.79 0.43 3.18 17.20 0.25 29.07 2.59 0.W 0.02 0.04 9.36 99.71 8.38 4.14 0.01 Wd9 W DME088.12 W93 6173710 47.15 0.88 14.80 10.19 0.16 5.03 9.47 3.69 0.34 0.24 0.06 99.01 5.197.01 0.01 W-50 baM DME088.5 395556 6178281 37.70 0.01 0.40 12.05 0.08 37.20 0.05 0.W 0.w 0.W 12.69 101.02 2.90 2.13 0.08

W-51 b-n DME88.105 379844 6170461 S.18 0.72 14.52 9.10 0.14 5.09 12.11 3.30 0.80 0.21 3.01 IW.01 7.10 2.97 4.01 W-52 b-n DME88.109 378744 6man 50.82 0.83 11.38 10.94 0.21 8.57 11.72 1.03 2.74 0.36 1.28 99.58 7.81 4.15 0.08 W-53 b& DME0811.14 387114 6174912 52.63 0.81 18.83 6.W 0.14 4.43 7.69 3.20 1.58 0.20 3.11 99.54 3.55 0.15 0.01 W-54 W DMEBB-118 386911 8179401 4276 2.38 12.52 13.42 0.28 9.89 10.57 1.80 0.92 0.67 4.39 99.40 9.95 0.78 4.01 W-55 basan FFE88.7.9 390909 6172014 49.90 0.91 15.16 10.80 0.19 0.12 7.55 3.49 1.97 0.58 3.02 99.89 7.39 0.16 4.01

W-56 b-n FFEBB-1314 385201 6170607 48.01 0.83 17.81 10.M 0.22 4.98 8.35 3.33 2.20 0.30 3.11 99.m 8.89 1.56 0.18 - w-57 basan FFEBB17d 385390 6177694 49.69 2.11 16.48 11.76 0.19 3.53 7.05 4.66 1.25 0.41 3.M 99.98 4.79 0.w 0.01 N W-58 VI b-n FFE88.17-12 m80 6177929 48.70 1.71 17.56 11.29 0.19 4.79 8.93 323 1.35 0.20 3.89 9992 6.63 0.15 0.05 W-59 basah FFE88.1B6.2 m16179595 4523 1.78 17.88 10.60 0.17 0.11 6.61 1.63 2.29 0.38 5.10 9984 5.40 0.15 0.01 W.80 382788 6184523 50.17 1.01 14.02 1124 0.17 7.92 0.20 3.07 0.15 0.15 3.19 99.89 6.88 4.16 4.01

W81 6104523 50.19 1.01 14.01 11.20 0.17 7.92 8.18 3.65 0.13 0.15 3.21 99.02 5.97 4.15 4.01 WSZ 396471 6174980 47.75 0.90 16.Z 11.77 0.21 6.17 6.05 3.99 0.74 0.06 5.65 99.58 4.12 2.41 4.01 We 396471 6174960 48.81 0.81 16.31 11.28 0.18 5.57 6.74 3.57 1.45 0.24 6.70 99.72 4.69 3.28 4.01 W.64 398171 6174980 48.61 0.88 18.44 11.20 0.17 6.06 5.10 3.73 1.22 0.05 6.31 99.70 6.25 3.11 4.01 W.65 396471 6174980 47.74 0.72 14.50 9.61 0.20 8.09 0.W 2.51 1.33 0.18 8.86 99.74 5.11 5.13 4.01

W86 396471 61749M 6.09 0.02 15.61 10.53 0.14 5.61 5.85 2.67 1.69 0.04 11.17 99.92 0.11 0.74 4.01 w.67 396471 5174960 43.44 0.76 15.11 10.07 0.16 5.04 6.74 227 2.14 0.11 13.06 99.52 6.11 10.1 4.01 WBB 396471 61749M 48.57 0.72 15.19 9.73 0.16 3.93 5.88 1.96 2.79 0.05 12.% 99.94 3.12 10.1 4.01 W.88 396471 61749M 44.87 0.63 12% 8.63 0.21 4.10 0.99 1.54 2.62 0.16 15.30 99.58 3.69 13.2 0.01 w-m 401901 6166512 4826 1.62 17.01 12.32 0.12 6.30 10.45 2.68 0.56 0.29 1.12 99.71 9.1% 0.86 0.01

W-71 3769% 6180419 50.82 0.W 16.33 0.83 0.21 3.88 6.33 3.32 4.76 0.71 3.96 99.67 410 0.93 0.01 W-72 384307 6170301 u.49 0.67 11.79 9.02 0.17 1025 7.27 2.05 2.08 0.20 2.88 99.71 7.64 4.16 0.01 W-13 3749~ 6187123 49.06 1.29 14.82 10.94 0.19 7.72 8.01 3.73 0.16 0.12 3.88 99.75 0.98 0.69 0.01 w-74 399599 6175522 58.32 1.41 13.88 9.96 0.21 2.89 5.29 5.75 0.27 0.27 1.81 99.86 M M M w-75 399527 6175333 49.29 1.80 14.89 12.16 0.21 6.U 7.07 3.65 0.24 0.18 2.82 99.59 M M "a 47.82 0.8847.82 17.U 8.47 0.14 ~~56213.93 2.W ~~~ ~- ~ Msp GROUP CR03 cu pb Zn Ni M C, ea SI Rb zr Y Nb T. u m C. La CICQW N-3 x FQm PPm PPnW m pp" ~ E Fm wm Fm pm W" Fm - FmFmFm w-1 Bovldsr Cmh 0.01 121 51 ea n 18 e6 30 10 0.5 0.5 02 1 2 7 31 1 w-2 bulMr Creeh 0.02 bb i. 82 990 M M M MM 0.5 0.5 0.2 1 2.8 9 31 1 W.3 8iq cmuk M 8 18 40 e50 4100 130 120 190 19 21 12 91 17.0 2.7 46 91 13 Wd eig cr&i M 19 10 42 ea 41W 125 120 250 31 10 1s 4.1 17.0 4.7 47 rm 1n w.5 eig cr&i M 12 15 53 <50 24w 110 190 le6 30 19 1.5 3.9 18.0 3.7 30 73 24

W6 G.bbrn M 101 d 27 950 990330 40 48 12 20 4.0 4.5 4.5 4.0 4 40 35 w-7 Takia? 0.01 335 75 59 150 301 10 131 41 10 0.5 0.5 02 4 13301 W-8 Tee47 M 80 4 72 230 porn 40 82 17 P 4.0 1.1 12 12 B 14354 w-9 NiM Cmh M 74 <5 n 210 150 135 17 120 30 19 4.0 4.5 4.5 1.2 d 15 40 w.10 NiM Creeh M 536 64 130 120 110 40 130 34 23 4.0 4.5 d.5 1.o d 40 42

w.1 1 NiM Creek 0.01 355 82 37 180 237 10 143 49 10 0.5 0.5 02 1 5.1 17 30 1 w.12 NiMCreek 0.m5 15 64 190 190 m 10 1W 46 10 1.2 0.5 02 3.9 15 38 1 w.13 Tax07 M 122 4 109 <50 3oom U 95 25 19 4.0 45 2.0 1.5 14 27 31 4 w.,4 TS*W na 104 4 81 280 310 170 P 94 23 12 4.0 4.5 1.3 40 7 40 29 u W.15 Nina Creeh[Duplicais) M 51 <5 86 140 150 235 40 120 33 21 4.0 4.5 4.5 <1.0 d 40 41

W-16 Ni~Creek M 50 4 83 140 180 180 40 125 27 d e1.0 4.5 0.5 4.0 d 18 38 W-17 Nina Creek M 636 94 170 400 1m dl 135 39 11 4.0 4.5 4.5 4.0 6 <10 43 W-18 NiM Creek M 446 83 230 <1w 89 41 140 4322 4.0 4.5 4.5 4.0 5 40 40 - w-19 Nina Creek M 67 d 73 220 <1w 1M do 105 26 15 4.0 4.5 4.5

w.21 Nina Creeh M e64 05 232 35 47 1 87 31 8 Mna rm 8 20 27 32 W-P NiMCreek M 91 <4 78 24 78 82 5 .E 298 MM M 8 9 2225 W-23 BIYB Lab vDlEBniEI M B71w 1m em 1016 28 295 27 24 0.5 0.5 4.4 38 W-24 NinaCreeh M 528 34 M M M M M Mna MM M M M M" W.25 Nine Creek M 50 10 32 M "a M na M Mna MM M M M MMna

W-26 Nina Creeh 0.01 4 5 70 20 uo 111 15 193 93 13 0.5 0.5 0.2 7 IO 32 in 1 W.27 Nina CreeMDupleste) M 25 15 44 120 850 1M 10 110 46 10 0.5 0.5 0.4 1 2.1 10 27 1 W.28 Nina Creeh 0.02 25 15 U 120 850 1M io 110 46 10 0.5 0.5 0.4 21 10 n 1 W-29 Niw Creeh M 535 102 <50 240 150 dl 135 36 4.0 4.5 4.5 4.0 4 40 33 W-30 NiMCreeh M4 67 87 277 195 67 3 104 37 11 MM M 7 21 28 10

W-31 NiMCreek M 504 81 181 5s 128 toll 388 MM N 3 11 20 33 W.32 NiMCreek M 10 20 78 M Mn0 19 tn 37 10 Lrb ir i. b is is is W.33 Ni~Creeh 0.04 b is I. il is 81 45 673 34 10 bk b i* b ilbb W-34 NiM Creek 0.04 e65 e6 220 420 150 10 89 32 10 40 0.5 02 1 2.5 11 39 1 W-35 Nina Creek M 85 4n ea BM) 1M 43 270 87 12 4.3 4.5 4.5 4.n 13 24 20

W-38 N~M Cmh M 18 <4 83 24 e4 179 1 85 31 7 MM M 8 14 22 35 w-37 NiM Creek M 64 n ea 228 121 1n 6 125 39 11 MM Iy 4 16 32 38 Wm NiMCreeh M 15 4 65 481 1727 72 24 63 28 11 MM N 7 8 224s Wiu) NiMCmh M 508 77 238 us 278 7 109 397 MM N 8 1s 1n 31 W4 NiM Creeh n m4 194 301 29229 5 105 37 9 MM N 5 10 10 - ~~ ~~~~~~~~ -~ ~ .~ -~~ ~"~ - 37"" 7, rY ?!i !A0 sa 5. % Y Llh ?e rr w * I” - 2; Cr _. u rn u C. ca No. Pp” ppn pp” m PP” pp” Ppm pp” ppn ppn Pp” ~ ~~ ~~ ~ ~~ ~-wm Pp” wm pp” PP! m wm ”m wm Wd1 31 4 81 67 <8 163 78 58 10 59 24 9 MM M77 16 W Wd2 ea 4 116 17 e8 50 la6 231 20 117 39 10 Mrn M511 542 W43 28 4 92 122 <8 307 652 142 P 73 32 9 MM ~6 10 831 W44 6 4 52 76 <6 1M 426 138 3 113 89 10 MM rn6 14 3233 W.45 6 <4 55 65 <8 158 428 131 10 109 38 7 MM MI 12 25

Wd6 7 4 82 65 <8 228 1x3 1W 1 94 31 9 naM M34 21 38 Wd7 7 ‘4 82 92 4 237 1W 90 10 138 40 10 MM m69 21 37 W.48 11 d 76 0.10% <6 1201 13 15 6 27 8 7 MM n. M M 123 Wd9 127 <3 87 31 40 110 130 375 40 105 28 <5 40 0.6 2.6 ~1.0 13 PWQ W-50 10 r3 38 0.22% 40 300 <,w 34 40 60 d 14 do 4.5 4.5 do <5 d0 102 Q

w.51 1M r3 85 52 40 170 UO 790 27 591 15 27 4.0 0.7 1.3 1.7 6 40 23 Q W.52 134 R 1W 89 40 380 1W 5M 53 591 ‘5 7 4.0 0.8 1.0 2.0 6 ‘10 43 Q W-53 132 R 67 5 40 rm 1m 470 38 62 15 27 d.0 4.5 0.7 1.5 6 40 17 Q W-54 74 R 140 205 40 3w ZM 490 20 190 21- 37 3.5 1.7 4.1 4.0 40 65 51 Q W-55 146 <3 93 42 15 120 310 375 ea 110 14 14 <1.0 1.5 2.4 1.8 14 3227Q

W-58 pz r3 83 4 40 <50 720 680 56 591 1, 16 ‘1.0 0.9 1.8 5.0 11 40 33 Q - w.57 25 ‘3 129 4 15 e50 210 375 40 lea 25 29 2.0 0.7 2.8 1.2 P 51 31 Q N W.58 132 85 15 <10 e50 E€6 28 1101 10 2.3 4.5 1.3 <1.0 15 U2gQ 4 e m I8 w-59 115 d 104 65 <10 130 270 958 41 1301 20 19 1.7 1.4 3.4 1.3 19 41 35 Q W-60 121 4 so 85 40 270 c1W 250 40 79 20 7 4.0 4.5 0.6 4.0 6 16 37 Q

W-61 130 ‘3 1W 68 <10 38 W.62 215 ‘3 92 28 40 130 <1w 590 27 61? 8 21 do 4.5 2.2 <1.0 13 31296 W.63 190 ‘3 82 27 ‘10 120 %a 480 ?a 82 29 19 40 4.5 2.5 2.3 25 25 27 Q W.M 81 <3 108 42 <10 1M 250 375 32 1W 14 11 &O 4.5 3.0 1.5 8 28384 W.65 79 4 95 30 40 87 230 360 n 66 23 12 do 4.5 2.2 1.7 17 32324

W.65 58 <3 66 39 40 140 2M 290 52 94 15 6 4.0 4.5 2.5 1.5 6 25 34 Q Wd7 33 <3 101 27 40 n 240 275 57 94 16 23 4.0 4.5 2.3 2.7 zo WYQ W-68 15 <3 86 30 40 130 303 275 6s 81 I1 14 4.0 4.5 2.3 2.7 11 26 29 Q W-68 91 <3 56 26 40 120 303 385 93 n 20 IO 4.0 4.5 1.8 2.5 14 40 P Q W-70 8 <3 203 137 40 370 130 270 <10 150 27 12 4.0 0.6 4.7 1.8 19 42 49 Q

w.71 uo R 89 27 40 52w 1mo 120 587 9 <5 do 1.0 1.5 3.8 10 11 23 Q w.72 27 R 79 195 40 €€a830 46s ffi 85 17 19 e1.0 0.9 2.2 2.9 10 252gQ w-73 25 <5 85 65 <6 230 <1m 190 Q1 ffi 15 13 4.0 4.6 4.5 1.0 <5 40 37 w-74 14 5 41 2 8 13 193 us 13 194 68 10 0.5 0.5 0.7 17 5.3 I7 13 1 w-75 52 5 90 43 6 110 150 la5 13 102 49 IO 0.5 0.5 0.5 1 . 14 38 1 W-76 250 m 287 ~ APPENDIX IV LIST OF TRACE AND RARE-EARTH-ELEMENTDATA FOR SEVERAL NINA CREEK, TAKLA AND WOLF RIDGE BASALTS AND GABBROS

FIELD m MO Rb C, ea Sr nu T* Nb m e4 87Rb/BBSr?SnVl44Na NUMBER ppm wm wm ppm PP ppm ppmm pp”pp” pp” ppm FFEBB29.10 1 0.50 2 0.22 87 104 0.m 5.28 0.24 2.3 2.57 .1.75 0.0575€8 0.- FFE898.10 3 0.08 0.33 0 0.W 18 34 0.W 2.13 0.38 3.0 2.43 0.82 O.mo7W 0.190100 FFE8918Dg 2 008 -0.12 1 0.08 41 53 0.02 3.93 0.23 2.4 1.% .2.21 0.- 0.1987W FFE892527 2 0.04 0.20 18 0.08 874 1so 0.08 7.73 0.28 1.I 120 1.48 0.3177W 0.1791W FFE87-29.1 0 0.04 023 3 0.18 11% 775 0.02 13.05 011 2.4 128 0.43 0.W77W 0.213mo FFEBsS7 2 0.08 0.28 7 0.30 444 287 0.05 28.61 0.24 26 1Y 0.97 0.0114W 0.2oUao FFE89-2917 0 003 0.17 0 0.12 128 108 0.02 8.29 0.28 22 1.97 -371 0.0133W 0.1871W DMEBBlC-9 1 0.08 -0.08 5 0.13 150 114 0.12 28.99 0.34 2.7 127 4.20 0.127900 0.2m3W DMEBklC-9 8 0.05 0.81 41 1.45 1Dw 561 0.38 2540 0.48 26 0.87 0.W 0.- 0.1BSSW FFEBB7.9 4 0.04 0.70 n 0.93 338 399 0.08 u.25 0.56 8.5 1.85 0.89 0.3plWo 0.1441W FFEW-257 1 0.04 0.73 $3 3.14 755 879 0.08 25.94 0.32 1.S 1.34 021 0.297MO 0.~41~ FFE87d.2 1 0.04 5.73 1 0.05 228 0.01 17.81 0.34 0.5 0.70 0.11 0.01BWO ~ ~~~~ ~~~~~ 382 ____ ”~ . ”- ~ ~ ___ ~ ~ -

MAP V m u La ce PI Nd Yn Eu Gd lb OV Ha El Tm YbLu NUMBER ppm ~ PP ~ PP . ppm .. ppn ppm ppm FQm ”~wm wm . m ppm PP ppn PPm Pp” PP w.10 33 0.28 0.07 3.57 ll.u 1.94 lo.w 3.72 1.36 527 0.91 8.18 1.34 3.78 0.55 3.51 0.52 - W.20 N 30 0.25 0.10 3.87 1213 2.08 11.14 3% 1.26 4.91 0.90 5.81 1.21 3.52 0.53 3.38 0.47 m W.21 28 0.19 0.08 3.53 10.85 1.78 9.80 328 1.22 4.42 0.78 5.W 1.02 2.98 0.44 2.89 0.42 w-23 27 0.10 0.m 5.39 9.58 212 10.58 3.18 1.17 1.97 0.73 4.88 1.02 2.98 0.45 2.78 0.q w-27 35 0.17 0.W 2.W 9.91 1.91 ll.w 4.04 1.61 8.41 1.03 8.73 1.48 4.18 0.59 3.78 0.58 w.39 30 0.18 0.04 4.32 13.08 2.14 11.07 303 1.28 527 0.89 5.W 1.21 3.48 0.48 3.08 0.U W4 28 0.31 0.05 4.30 3z.n 2.04 10.81 358 1.22 4.w 0.79 5.19 1.10 3.11 0.48 2.88 0.W W-52 35 0.38 0.07 4.58 14.56 2.39 13.14 4.43 1.81 8.01 1.04 7.15 1.48 4.25 0.81 4.08 0.59 W.52 1217 1.34 0.w 8.51 14.14 1.98 9.01 2.45 o.n 3.18 0.40 2.41 0.51 1.35 0.21 1.29 0.18 W.55 2.32 0.03 14.15 28.44 3.48 14.52 3.45 1.08 4.w 0.56 3.81 0.89 2.02 0.27 1.83 0.27 w.71 12 1.22 0.78 225 9.m 210 0.80 281 0.38 2.32 0.47 1.39 0.19 1.29 0.19 W-18 14 0.07 0.01 0.70 3.w 1.43 0.67 253 2.87 0.56 l.W 0.23 1.44 0.21 ~~ 0.38 ~~~ ”” ~~~ ~~~~ ~~ ~~ APPENDIX V MINERAL ANALYSES USED IN GEOTHERMOMETRY CALCULATIONS

SAMPLE FFE35-7 SAMPLE DME 33-7 gar-mre gar-midgar-rim bio-rim gar-rim'bio-rim. bio-rimgar-rimgar-midgar-core n=l n=l n=6 n=8 n=5 n=6 n=5 n=ln=5 n=5 Si02 35.9037.0236.6936.8936.2537.16 37.2137.62 37.43 35.86 Ti02 2.680.00 0.01 0.01 1.89 0.02 0.00 0.00 0.01 I.85 A12 03 20.20 20.26 21.03 19.93 21.04 19.2721.04 19.93 21.03 20.26 20.20 A1203 20.17 20.81 20.55 21.42 Fe203 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 CR03 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 31.55 30.66 29.44 19.96 29.32 19.39 31.08 32.18 33.63 19.40 33.63 32.18 31.08 19.39 29.32 19.96FeO 29.44 30.66 31.55 6.23 7.63 8.45 0.39 8.50 0.31 5.83 4.97 3.37 0.18 3.37 4.97 5.83 0.31 8.50 0.39 8.45 MnO 7.63 6.23 2.96 2.82 2.71 9.11 2.72 9.31 3.38 3.33 3.41 3.33 3.38 9.31 2.72 9.11 2.71MgO 2.82 2.96 9.74 BaO 0.00 0.00 0.00 0.12 0.00 0.15 0.00 0.00 0.00 0.05 C aO 1.35 1.28 1.41 0.01 1.42 0.01 1.41 1.28 1.35 CaO 0.001.62 1.54 I.34 0.00 Na20 0.00 0.00 0.00 0.14 0.00 0.18 0.00 0.00 0.00 0.35 K20 0.00 0.00 0.00 9.37 0.00 9.40 0.00 0.00 0.00 9.01 F 0.070.03 0.03 0.24 0.030.03 0.28 0.020.33 0.03 99.21 99.42 100.11 97.10 100.20 97.18 100.70 99.80 100.31 96.94100.31 99.80 100.70 97.18 100.20 97.10 TOTAL100.11 99.42 99.21

Si 3.002 2.981 2.984 2.694 2.992 2.710 2.999 3.000 2.999 2.681 Ti 0.000 0.001 0.001 0.107 0.001 0.151 0.000 0.000 0.001 0.104 AllV 0.000 0.019 0.016 1.306 0.008 1.290 0.001 0.000 0.001 1.319 AlVl 1.935 1.919 1.980 0.456 1.987 0.409 2.009 1.951 1.962 0.458 Fe3+ 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Cr 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Fez+ 2.147 2.083 1.985 1.252 1.974 1.212 2.072 2.170 2.253 1.213 Mn 0.429 0.525 0.577 0.025 0.580 0.020 0.394 0.339 0.229 0.01 1 Mg 0.359 0.341 0.326 1.019 0.326 1.038 0.402 0.400 0.407 1.085 Ba 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Ca 0.118 0.1 11 0.122 0.001 0.123 0.000 0.114 0.133 0.139 0.000 Na 0.000 0.000 0.000 0.020 0.000 0.026 0.000 0.000 0.000 0.000 K I 0.000 0.000 0.000 0.8971 0.000 0.0000.8971 0.000 0.000 0.859 Xal 0.6810.703 0.660 0.657 0.695 0.713 0.744 XSP 0.1920.1720.141 0.0760.112 0.132 0.118 0.112 0.108 0.109 0.135 0.132 0.134 0.132 0.135 0.109 0.108 IXPY 0.112 I 0.118 I O.Ig3 I I 0.039 0.036 0.040 0.041 0.038 0.044 0.046 0.044 0.038 0.041 0.040lXgr 0.036I 0.039 * Analysis pair is from abiotite inclusionin garnet. Abbreviations: gar= garnet. bio =biotite. core = core of crystal, mid= middle of crystal, rim= rim of crystal. n = number of analyses averaged.

129 L.6 DME87-154P Qo 4.5 9 '4 6 25 1 L.7 DME87-16% a0 4.5 44 15 26 25 4 L-8 DME87-16.13 a0 4.5 40 13 55 46 4.0 L-9 DME87.1616 a0 4.5 375 23 106 It6 25 L-IC, WE67-184 do 4.5 5 12 14 15 ~1.0

L.ll DME87-224 a0 4.5 12 16 80 c10 2 L-12 DME8741-2 <20 45 16 e4 31 44 9 L-12, FFE87.1-1 273427 461 37 0.11% 20 34 L-14 FFEOl2 Qo 254 0.32% 12.60% 0.25% 10 6 L-15, FFEllDZ 188 31 720 137 3% 90 58

L.16, FFE11-1 135 e4 3 0.54% 3 <10 13 L.17 FFE87-13-2 -20 2 72 da 1502 da da L-lEi FFE87.16-2-2 a0 4.5 37 7 14 <10 2

L-151 FFE87-16-2.2 a0~~ 4.5~. ,I 4 8 32 <1 L-20 FFE67-16.24 do 4.5 5 4 20 34 '1

L-21 FFE87-16-9-2 Qo ~0.5 7 6 43288 6 L-Z! FFE87-203-2 Qo 4.5 3 4 3 11 4 L-2:i FFE87-21-9 Qo 4.5 3 4 4 24 12 L-24 FFE87-22-7 a0 4.5 9 '4 14 40 4 L-2!i FFE87-22-74 <20 4.5 2 <4 5 <10 <1

L-xi FFE87-262 a0 '0.5 2 4 3 28 <1 L-2;' FFE87.27-10 Qo ~0.5 8 12 84 40 4 L-Zli FFE87.29-2-1 31 ~0.5 10 10 59 1165 4.0 L-XI FFE87-29-2.1s 61 4.5 9 4 23 290 7 L-YI FFE87.29.2.1 b Qo <0.5 61 14 29424 1

LD'I FFEB72%2.5 40 4.5 210 13 €8 28 8 L.S! FFEB748-3-1 Qo 4.5 8 11 12 '10 2 L.ll FFE874g-1 Qo 4.5 40 4 75 90 3 L-3'1 FFE87494 a0 4.5 6 17 33524 L.3!i FFE87-5D3 Qo 4.5 7 da 18.7 da Ma

L-X1 FFE87-50-3 a0 4.5 10 33 103882 L-37 FFE87-52-7.1 a0 4.5 240 6 163 <10 ~1.0 L-Yl GM87Bd-1 a0 45 3 4 3 22 <1 L-3'3 GM87-18-2 do '0.5 B It 22 40 130 L.40 WEBB-24.5 164 128 0.78% 3 mn IJ~480

L4I DMEBB44 1283 17 380 57 7 L4:? DMEBB-5-1-1 24 3 165 112 29 23 €6 L.41 DMEBB-5.1-2 5 -5 7 12 76 12 13 L4 DMEBB-5-3 1 .5 I1 3 53 10 44.5 9 M M 5.7NIn L-95 WEBB.llB 6 .5 103 3 61 10 3 0.5 5 M M 5 <7 N N

L*P DMEBB-18-4-3 11 -5 32 7 16 135m 9 12 9 N M 143 -7 n M L47 DME88-21-10 1 .5 141 9 104 240 4 0.6 24 M M 22 e7 M M L-4% DMEBB-21-16 1 -5 73 7 108 25 3 4.5 27 M M 39 <7 M N L43 DMEBB-25-1-1 2 .5 48 10 Eo13055 851 MN~%<~MM L-53 DMEBB-25-1-2 1 .5 20 4 28 175 5 3 24 M -441 <7 M M

L.51 WEBB-28-3 1 1 7 44 48 37 15 3 15 M ~237<7 M M L-52 DMEBB-286 1 .5 141 12 90 10 1 0.7 12 M M <737 M M L-53 DMEBB-28S 28 450 0.53% 980 0.11% 1W 249 0.24% 10 M M 448 -z7 M M L-54 DME88-27-1-2 1 0.5 187 3 21 14 2 4.5 20 M 23M M 4 M N L-55 DMEBB-33-5 14.5 2 5 3 <10 14.5 51 M4W M 4 M M

L-58 DMEBB.344 14.5 58 3 99 12 14.548 MISOMrB" L.5I DMEBB370.1 1 4.5 1 4 5 '10 1 4.5 77 M 120 N 4 N N L-58 DMEBB.37-3.2-L-58 391488 6178794 lstvanita 1 4.5 102 3 106 13 225 3 44 N 610 M 4 N M

131 w FiELD UTM UTM Rack Au As cu Pb .a Hs As Sb Co Ni Ba W Mo Bi Gs No. NUMBER EesW NamikQ Typ ppbppm PP~ppm ppm ppb PP~Ppm PPmPPm Ppm PPmPPmPPm PPm M L-59 DLlEBBOlJ.3~ 6179793391488 ~~ OUaltlYein 1 6 50 4 31 310~~ 21 54 52 M4M M4 M Lbo DMEBBd4.1 1 4.5 51 14 55 36 4 3 LBl DMEBBd4-2 1 4.5 182 3 29 34 150 3 La DMEBBd48-2 3847M 6192712 w- 1 4.5 55 3 72 47 5 2 La DMEBBd66-1 394988 8180580 q"am"ein 1 0.6 12 4 40 42 3 5 L64 DMEBBd6.2 394988 6180580 quamvein 1 4.5 5 4 14 20 <1 '0.5 L.65 DME88-464 394988 6180580 quamvdn 1 4.5 7 4 31 16 23 2 Lb6 DMEBBd6d 394988 6180sBo quam vein 1 4.5 3 3 16 11 7 ~0.5

L.67 DMEBB46-5 394988 6180580 quam vein 7 4.5 7 6 18 30 5 e0.5 La DMEBBd6.6 394988 8180580 quam vein 1 4.5 2 38<10 1 4.5 L.69 DMEBBd66-9 394988 6180580 quam "3" 1 1 8 412 480 Mo 14 e0.5 L-70 FFEBB.2-7 3WM 617W1 qmI1Ivein 1 4.5 11 19 5 26 2 5 L.71 FFEBBB-1 09177 6172403qusmzvein 143 4.5 101 3 68 11 32 1

L-72 FFEBB-9-1-1 3962756175343 mred andesite 10 .5 104 9 84 10 2 0.9 98 M na L-73 FFEBB-10-2 3988176173510 qu~slrinprr 20 .5 40 10 32 20 33 e0.5 9 Mna L-74 FFEBB-13-10 385208 6170146 silrifed andesite 10 .5 117 15 74 10 1 2 14 M na L-75 FFEBB-13-11 385265 6170398quamzvsin 1 r0.5 63 3 23

L-81 FFEBBJI4-4 394926 6180612 quamvsin 66 52 1.w, 337 690 8rn 22 5 3 M 65M L-62 FFEBBJId-5 394926 6180612 quam vein 3 4.5 4 4 20 30 3 4.5 7 na 2w L-83 FFEBBd6d-1 3953576184044 sheared basti 1 4.5 24 3 32 31 10 '0.5 8 na 210 L.84 fIARBBd.5 388368 6176473 andssib 3 .5 119 15 96 10 3 0.7 15 M M L-85 RARBB-54-2 3852166167766 qmmvein 1 0.6 3 5 13 40 4 <0.5 5 na <1w

L-86 RARBB-103 385408 6189945qUaltZVBin 1 4.5 38 3 78 140 6 1 7 M 280 L-87 RARBB-108 384225 6191676 quamvein 1 4.5 10 15 25 45 1 45 6 M 170 L-BB DME89-1-5 386016 6196620 rilicifled tun r2 4.3 45 * 82 52 2 0.8 26 51 M LBO DME89-3-1 3861496197123 Sibifeddotile '2 4.3 58 4 Ed '20 <, 4.5102 40 M L-go DME89-12-3 382455 61986s~mwred barn 6 4.3 51 4 73 '20 1 0.6 30 83M

L-91 DUE84134 385231 61- dnrk '2 4.3 55 4 82 '20 (1 3 36 49 M L.02 DME8414-2 -7 6201744 qunmvsin 6 <0.3 142 3 87 72 13 0.6 20 17 M L.93 DME8414-2D 3848376201744 quaevein 6 ~0.3 144 6 66 83 12 0.5 23 23 M L-94 DME8415-7 3m6202872 bBmn 2 ~0.3 49 4 69 40 <1 0.5 34 44M L-95 DME69-SI3 3785336219441 quamzvsin 4 ~0.3 67 10 56 22 5 <0.5 11 M M

L-96 DME8428.2 2841966218091 cakam"P6iils~ 2 0.3 27 24 270 3w 1 0.7 24 M M L.97 DME89.43.2 3824286210161 dlemdd*m 2 43 345 4 37 '20 2 <0.5 4 10 M L-98 FFE69J-1-3 390200 62w191 ma8dVB sulpha8 2 64 51 5.2% 8.70% 173m 16 58 6 ~na L-99 FFE894J-2 3912806199124 breccia 2 0.3 2 15 10 20 1 0.5 3 MM L-lw FFE89.7.21 3891946202531 WSiWsulphide 2 115 150 0.67% 14.70% l85m 13 18 3 MM

L-101 FFEBO-74-3 388480 6203882breccia 2 28 BB 10 4.11% 62m 3 3 3 MM L-102 FFEBO-7.5 388163 6203970 brmIed6ilslw-a 2 32 16 5.40% 20 308 240 42 9" L.103 FFE89.7.5D 388463 6203670brecciated 6inslm 4 32 17 5.50% 16 335 244 36 7" L-104 FFEBO.10-10 3969376194074 &lomile 2 0.3 3 19 15 29 3 0.9 3 MM L-105 FFE89-13-16 3921216202705 cerbbonats breccia 2 0.3 3 60 94 31 2 0.6 3 MM

L.106 FFE89.lS4.1 383933 6197341altered basil '2 <0.3 48 4 47 136 3 <0.5 30 58 M L-107 FFE89.15d.2 383933 6197341altered basan <2 <0.3 22 436 50 2 <0.5 16 34 M L-108 FFE89-15-4-3 383933 6197341ailered basan 16 43 29 4 41 47 3 4.5 17 42 M L-lW FFE8418d 377358 6201662 altered basail 10 '0.3 52 4 59 <20 1 <0.5 34 61 M L-110 FFE89-26-8-2A 384229 8215216 &hk 4 0.3 6 65 38 178 61 4 3 MM

L-111 FFE89.28.8.28 384229 6215216 &lomi 4 0.3 179 47 114 59 4 3 Mna L-112 FFE89-28.10 3839736214855 maMivB 6"iPhlde 2 0.8 46 0.32% 133 7 6 3 nana L-113 JwH8sd-7 38wu 6211173 ansredchen 4 4.3 149 6 112 <20 6 4.5 22 83M L-114 JWHB94-13 3797246211887 quamveh 8 4.3 114 25 26 '20 13 4.5 2 ana L-115 JWHBS-63 3799476216777 allsredpabbm 6 4.3 217 4 45 '20 <1 4.5 32 74 M L-116 JWHB906-2 380210 6197118 sitemdargiiiile 22 0.6 48 13 Ed 485 10 2 5 30M

unmc AU Ni Cr Hs AI Sb pt Pd ROCb wa x PPm wa Ppm PWPpb Ppb L-117 DMEBB-2-16176334397764 mcpnlim 1 0.19 2556 40 4 45 4 6 L-118 DMEBB4.3-2 817CU23405418 IsluBnll*68wntiM 1 0.10 3403 15 19 0.9 8 6 L-119 DMEBBd-2 3954106178720 ~cpnlim 1 0.25 2965 40 1 3 8 7 L-120 DMEBB44-12386127 6177740 68cpntine 2 0.20 2435 40 1 45 4 5 L.121 FFEWl0-9 395374 617W7 wnti~ 1 0.25 3096 '10 335 13 7 9 L.122 WEBBUS 6211375378517 ~cpntim 2 7ykn M 57M Mna na m-PPm M .mt mawzed

132 APPENDIX VI1 1983 REGIONAL GEOCHEMICAL SURVEY, STREAM SEDIMENT GEOCHEMISTRY FOR SAMPLES COLLECTED DURING 1987 AND 1989 (1)

MAP SAMPLE NTS UTM VTM 4 Zn Cu Pb Ni Co Mn Fe Mo Wo As Sb Hg U Uh Flh pHol No. NUMBER shssl Earlno Northh) ppm ppm ppm ppm ppm Ppm ppm % wm ppm ppm ppm ppb ppm Wale, Wale, Wstsr - (wb) (wb) (PPb) R.7 831502 93W 429808 6154153 0.1 59 25 3 30 7 377 1.80 1 3 0.27.0 30 3.4 0.49 68 7.6 R-2 831503 93W 428806 6154153 0.1 55 24 2 31 6 380 1.70 1 4 5.5 0.4 30 3.6 0.45 58 7.6 R-3 631504 931119 432248 6152294 0.1 108 30 5 50 11 1240 2.30 1 4 0.90.0 50 2.4 0.03 60 7.7 R4 631505 931119 433869 6153439 0.1 72 25 7 35 6 377 2.20 1 2 6.0 0.3 50 6.7 0.W 50 7.5 R.5 8x506 93~434207 6153499 0.1 35 11 2 17 4 207 1.20 t 2 2.5 0.1 20 10.4 0.13 46 7.2 Rd 831507 93W 4359376152938 0.1 28 8 1 12 3 160 3.90 1 3 1.5 0.1 20 9.3 0.14 40 7.0

R-7 631W 93W 433434 6163770 650.2 10 4 17 6 3M 1.40 1 11 5.0 0.1 40 10.0 0.16 42 6.1 R-8 831YX 93W 428829 6169150 0.1 33 6 1 11 3 240 0.90 1 2 2.0 0.1 20 5.6 0.45 24 6.5 R-9 631510 93W 426462 6168068 0.2 33 7 1 16 2 127 0.80 1'' 2 1.5 0.1 30 9.2 0.47 30 7.5 R-10 631512 9W438136 6174717 0.3 58 13 10 16 6 112 1.50 1 2 2.5 0.1 40 12.0 0.34 54 6.7 R-ll 831513 93W 435593 6175642 0.3 51 11 10 16 3 1.20144 1 1 1.0 0.1 40 16.4 0.24 40 6.8

R-12 631514 93W9 435257 6175888 0.2 60 12 6 17 15 3130 7.W 1 I 6.0 0.1 60 6.0 0.01 34 6.3 R-13 831515 93W 433249 6174595 0.1 32 3 4 9 4 430 1.20 1 2 6.0 0.3 20 6.2 0.04 52 6.6 R.14 831516 93w 4nm 6173161 0.1 25 1 5 3 1 1st 0.45 3 1 1.520 0.2 10.2 0.40 34 6.5 R-15 831517 93W 425816 6173994 0.2 25 1 3 3 2 373 0.65 1 1 1.0 0.1 20 11.0 0.17 30 6.2 R-16 831510 931119 424527 6173588 0.2 26 1 2 4 3 144 0.50 1 1 1.0 0.1 30 6.9 0.60 30 6.1 R-17 831519 93W 423029 6173843 0.3 38 2 6 7 27 2960 2.70 1 2 1.5 0.1 40 6.9 0.21 30 6.1

R-18 631520 93W 420816 6174739 0.3 34 3 4 8 6 335 0.95 1 2 1.5 0.1 40 16.4 0.16 30 6.3 R-19 831522 9W411324 6179055 0.1 24 6 1 9 5 174 0.80 1 2 2.5 0.1 40 10.0 0.04 26 6.4 R-20 831523 93W 4079% 6177774 0.1 30 18 1 16 4 4C9 2.65 1 1 1.5 0.1 190 7.2 0.01 48 7.0 R-21 831524 93~407934 wrn4 0.4 42 17 2 22 7 174 1.a 1 1 1.5 0.1 ?IO 6.3 0.01 7.1 52 R-22 031525 93W 408656 6174583 0.3 35 2 11 21 6 375 1.65 1 4 1.5 0.2 60 11.4 1.20 88 7.5

R-23 831528 9YM US079 6171787 0.1 25 15 1 22 8 313 1.70 1 3 3.0 0.3 50 9.6 0.22 52 7.4 R-24 831527 93W 415585 6175345 0.1 16 1 1 7 2 69 0.60 1 3 1.0 0.1 30 11.2 0.M 24 6.6 A-25 831520 93W 415247 6171740 0.1 29 5 1 11 6 236 0.95 1 1 1.0 0.2 40 11.9 0.12 38 6.4 R-26 831529 93W 420434 6170192 0.2 46 7 3 12 7 576 1.50 1 1 1.0 0.2 50 10.1 0.01 36 6.0 R-27 831530 93W 417291 6167949 0.1 43 6 1 16 6 126 1.40 I 2 1.0 0.2 40 3.2 0.20 60 7.7

R.26 831531 93W 420541 6164719 0.2 46 29 1 11 2 132 0.50 1 1 1.0 0.1 140 14.8 0.12 62 6.3 R-29 831532 93W 424265 6168926 0.1 38 4 2 10 4 242 l.W 1 1 1.0 0.1 40 11.4 0.50 36 6.5 R-30 831534 93W 426814 6160479 0.1 46 11 4 15 6 239 1.40 1 2 1.5 0.2 30 8.0 0.48 38 6.0 R-31 831535 93W 423240 6158443 0.1 62 30 4 37 12 498 2.20 1 2 6.0 0.3 W 2.8 0.10 52 7.6 R-32 831536 93W 423922 6154756 0.2 25 6 1 7 2 210 0.50 2 1 1.5 0.1 60 1.5 0.01 56 7.6

R-33 831537 831119 421705 6155382 0.6 116 38 5 78 14 427 2.20 2 2 6.0 1.0 60 3.7 0.10 54 7.8 R-34 831538 93W 4202106153229 0.3 62 29 4 63 11 272 1.70 2 2 3.0 0.4 30 3.6 0.06 56 7.3 R-35 831539 9W419398 6155770 0.2 60 21 5 40 10 2.10264 1 2 4.5 0.4 20 2.6 0.03 56 7.4 R-36 831540 93W 420068 6155051 0.2 62 23 6 42 10 305 2.10 2 14 5.5 0.2 30 6.1 0.04 48 7.2 R-37 631542 9W416804 6152366 0.2 20 4 1 3 1 228 3.40 5'. 1 1.5 0.1 60 0.0 0.04 42 6.7 R-36 831543 93W 415798 6152924 0.2 46 20 1 16 10 251 1.55 2 3 1.5 0.2 20 9.4 0.27 36 6.6 R-39 831% 93~415796 6152~40.1 50 21 2 19 10 268 1.60 2 2 1.0 0.1 20 10.5 0.27 36 6.5 R-40 831545 93M 414033 6154814 0.1 80 27 I 16 7 1M 1.20 5 1 1.5 0.2 30 14.8 1.15 32 6.6 Rd1 831546 93W 415903 6156560 0.1 74 21 3 46 B 328 170 3 21 3.0 0.2 20 3.6 0.04 35 7.0 R-42 631547 93W9 406868 6153969 0.2 34 4 4 5 5 1030 1.45 3 1 1.0 0.2 30 23.6 0.80 32 6.2

R-43 831546 93W 406541 6154150 550.2 6 2 5 5 1570 1.90 3 1 1.5 0.2 40 17.0 0.06 30 6.3 R~44 831549 93W 4074486154714 0.2 47 15 3 7 4 391 1.20 1 1 1.5 0.2 30 6.6 0.18 32 6.5 R-45 631550 93W 407866 6160245 0.2 17 32 2 16 3 211 1.05 2 1 2.0 0.1 50 20.20.12 40 6.6 R-46 831552 931119 408542 6150405 1.0 37 54 1 12 7 427 5.30 12 1 11.0 0.5 130 155.5 0.26 48 7.7 R.47 831553 9W411681 6163011 0.2 2064 9 56 12 335 2.10 1 3 11.0 1.2 50 3.9 0.10 60 7.2

R4 831554 93W 413847 5163745 0.5 240 4 99 60 12 398 2.10 4 1 12.5 701.7 2.7 a47 68 7.9 Rd9 631555 93W 418887 61-1 0.1 30 80 1 25 0 697 2.10 1 I 2.0 0.1 110 1.4 0.01 56 7.5 R-50 831556 93NA -2 6168302 0.3 118 55 14 88 16 716 2.90 5 4 12.5 0.9 30 2.6 0.30 7.6 64 R-51 Wl8 9W410358 6171206 0.5 110 34 15 48 12 768 2.55 2 1 9.5 1.2 60 4.8 0.12 160 8.0 R-52 833019 9YM 411885 6170170 0.3 40 12 3 20 8 324 1.40 1 1 1.0 0.1 40 11.2 0.24 28 7.3

R-53 aWy0 93W 41547 6165239 0.8 72 46 5 48 14 749 2.45 1 1 5.0 0.6 50 2.9 0.20 64 8.1 R-54 833022 93W 417063 6150465 0.3 51 35 5 32 4 248 0.80 1 I 2.0 0.1 160 30.6 0.08 36 7.6 R-55 833023 QW 420356 6157802 0.4 M 31 5 39 13 562 2.25 1 1 4.5 0.7 70 2.7 0.07 54 8.1 R-56 833024 9311") 425586 6157247 0.2 37 11 3 20 6 309 1.20 1 5 1.5 0.1 30 3.4 0.13 44 7.4 R-57 -5 93W 426117 6156736 0.2 36 15 5 26 7 303 1.50 1 6 1.0 0.1 30 3.6 0.03 48 7.5

R-56 %33026 93W 429285 6155376 0.2 32 12 4 M 6 225 1.25 1 5 1.5 0.2 20 4.1 0.05 42 7.2 R-59 833027 93W 429265 6155376 0.2 32 13 4 21 6 237 1.35 1 9 1.5 0.2 30 5.0 0.23 42 7.4 -R-60 633028 93W 433456 6155745 0.4 51 37 5 32 10 598 2.10 1 1 4.5 0.4 30 4.9 0.04 -46 7.4

133 Rd2 0.1 21 11 2 13 4 23d 0.85 1 1 1.0 0.1 20 5.1 0.M 40 7.1 R43 0.2 28 14 2 18 8 319 1.15 1 1 1.5 0.1 20 5.8 0.01 U 7.3 RU 0.1 50 15 3 n 8 ly) 1.35 1 1 2.0 0.1 30 5.1 0.01 42 7.5 RB6 0.1 38 27 1 25 8 319 2.00 9 1 3.0 0.7 1W 1.8 0.01 30 6.8

RBB 0.1 84 80 1 40 12 661 3.80 2 1 6.0 0.5 270 1.4 0.01 32 7.8 R.67 0.1 28 39 1 8 4 3380 18.W 2 1 28.5 0.3 280 0.8 0.01 34 7.9 RBB 0.1 70 1Ds 1 Y) 20 1510 4.70 2 111.5 1.4 654 1.1 0.01 30 7.6 R.69 0.1 75 102 2 52 21 878 4.45 2 1 9.5 12 4ca 1.0 0.01 a 7.5 R-m 0.1 28 14 1 14 6 257 2.00 1 85 3.0 0.6 80 19.3 0.39 30 7.2

R-71 831m 9WlO 378318 8189685 0.2 29 16 1 14 6 266 1.70 1 10 2.0 0.5 40 6.5 0.40 30 7.1 R-72 831m9 9W10 380487 6168150 02 55 18 1 16 7 246 1.80 1 1.515 0.4 40 28.0 0.51 28 7.0 R-73 831011 W10 378757 61- 0.1 29 22 1 15 7 389 1.15 1 22 2.50.4 50 13.8 0.43 26 7.1 R-74 831012 W10 377735 6158246 0.6 66 35 1 17 16 4Mo 4.45 4 6 10.0 0.4 120 19.5 0.08 30 7.4 R.75 831013 93W10 376678 6168795 1.0 21 143 2 13 6 290 1.30 1 3 2.5 0.5 220 37.6 0.12 28 7.0

R-76 831014 W10 374383 6170314 0.1 50 27 1 25 14 802 3.W 1 1 4.5 0.5 50 1.9 0.01 26 7.5 R-77 831015 9W10 387497 6176733 0.1 BB 51 1 15 14 553 3.50 1 1 2.0 0.8 70 1.9 0.01 28 7.2 R-78 831016 9WlO 391080 6173453 0.2 76 70 2 25 13 317 3.80 2 111.0 1.3 80 3.9 0.W 34 7.6 R-79 831017 9W10 39M9 6176852 0.2 54 65 1 20 14 579 3.40 1 1 2.5 0.5 80 1.5 0.01 32 7.4 R80 631018 W10 395583 6175434 0.2 52 69 1 19 8 306 2.30 1 1 0.5 0.4 130 2.4 0.01 34 7.1

R-81 831020 9WlO 395196 6176310 0.1 46 72 1 15 10 254 2.50 1 1 3.0 0.6 180 1.2 0.01 m 7.5 R42 831W 9W10 397396 6176358 0.1 74 17 4 15 10 588 3.30 1 2 3.5 0.5 40 1.8 0.01 34 7.9 R-83 831023 9W1040269 6174751 0.1 69 29 8 143 16 612 3.40 1 4 28.5 1.4 70 2.3 0.01 40 8.0 RM4 831024 9W10 W119 6177873 0.1 46 21 2 30 10 345 1.90 1 2 2.0 0.6 50 8.5 0.12 26 7.2

R85 831025 9W10 402891 6178111 02 52 58 51 4 13 636 3.W 1 1 8.5 1.4 140 2.4 0.01 42 7.5 Rg6 831028 9W10 4M38J 6170963 0.4 68 58 1 12 6 487 2.W 1 2 2.0 0.6 180 3.3 0.08 40 7.7 RB7 631027 9W10 403840 6168717 0.3 98 53 11 52 14 709 3.25 . 711.0 0.9 30 3.0 0.13 36 e.9 RBB 831030 83NllO 397832 6164ea 0.1 29 17 1 10 5 353 1.45 1 2 1.0 0.4 20 7.3 0.22 28 6.9 RB9 831W1 93Nl10 394585 6167491 0.1 57 30 2 26 10 575 2.55 1 1 2.5 0.5 30 5.3 0.23 32 7.0

R-80 831672 9W10 m40 6178765 0.1 66 120 2 21 19 766 3.45 2 1 2.0 0.3 1M 1.1 0.01 44 7.5 R-91 831673 9WlO 382115 8171489 0.1 70 28 7 w 11 388 220 2 5 4.5 .- 80 4.6 0.05 42 7.2 R-92 831674 W10 387397 6171531 0.3 122 80 4 28 21 514 3.30 2 2 16.5 0.4 50 4.2 0.30 48 7.6 R-93 831675 9W10 388398 6171SY 12 430 1W 8 72 26 1220 5.25 13 1 73.0 3.4 50 4.0 0.09 52 7.8 R-54 831678 9W10 3886878167.529 3.2 235 28 io 22 11 1050 3.W 3 1 3.5 0.1 180 392 0.22 44 7.2

R-95 8316n WIO 392025 6166128 0.1 84 35 4 14 10 358 2.00 1 1 3.0 0.1 24 11.3 0.26 44 7.0 R-96 831678 9WlO 382022 61W 0.1 53 22 2 14 10 478 2.M 1 2 2.0 0.1 50 10.1 0.24 50 7.0 R-97 831680 W10 382881 6186215 0.1 48 33 2 25 11 407 2.M 1 1 5.5 0.1 80 5.8 0.33 52 7.0 R-96 833m2 WlO 378733 6173215 0.1 55 50 4 48 16 513 3.W 1 1 3.0 0.4 210 1.0 0.01 26 7.9 R-98 awxU W10 382422 6174402 0.1 78 78 4 5% 17 597 3.20 1 1 3.0 0.4 100 1.1 0.01 54 8.0

R-1W 8XKC4 W10 3E-395 6175317 0.1 48 45 21 2 9 4ca 1.30 3 1 18.0 0.8 70 1.8 026 62 82 R.101 831585 93Nl15 398191 6185769 0.4 53 36 4 68 15 430 2.50 1 1 10.0 0.7 40 3.7 0.12 42 7.4 R-102 831816 93Nl15 401W 8189532 0.1 25 11 2 18 6 204 1.25 1 1 1.5 0.2 20 5.8 0.13 44 7.2 R.103 831617 W15 4C5%5 6187491 02 30 15 1 16 7 166 1.30 1 1 1.0 0.2 20 7.3 0.09 44 7.2 R-104 831818 9W15 401575 61W 0.1 62 30 5 37 17 756 3.W 1 1 11.0 1.1 90 2.5 0.01 72 7.9

R-105 831619 9W15 403515 6180176 0.1 24 12 1 15 161 7 1.10 1 1 1.0 0.3 20 5.5 0.18 42 7.0 R-108 831620 W15 UmBO 6164360 0.1 43 23 1 28 12 1540 1.96 1 1 1.5 02 40. 1.4 0.01 80 7.5 R-107 831W 93Nl15 395131 81QB574 0.2 35 82 2 23 8 300 1.50 1 2 1.5 0.3 180 1.1 0.01 38 7.1 R-108 831823 93Nl15 4OZ3CO 6191591 0.1 35 15 1 57 8 740 1.45 1 1 6.0 0.2 50 5.2 0.12 110 7.8 R-109 831624 93Nl15 3m8192403 0.3 203 72 17 82 19 816 3.10 2 1 4.5 0.6 80 4.5 228 66 7.4

R-110 831845 93W15392721 616959 02 114 36 1 70 16 972 13.50 3 1 79.0 0.2 140 1.6 0.08 64 7.3 R-11 1 831847 W15 381818 8189264 02 42 34 1 m 15 378 2.30 1 1 1.5 0.1 90 1.4 0.01 54 7.3 R-112 831648 W15 387292 Elm9 02 5353 1 39 21 SBO 3.35 1 1 2.5 0.2 80 1.0 0.01 46 7.4 R.113 831667 W15 378014 6102074 1.1 42 215 2 40 14 42 2.40 1 1 4.5 22 122.3 2.8 0.02 42 7.4 R-114 831868 W15 376700 61suDD 0.1 42 90 3 26 10 265 1.45 3 1 3.0 0.1 210 1.5 0.01 54 7.3

R-115 831689 W15 3809oO 61829m 0.1 37 42 1 13 10 656 2.W 1 1 2.5 0.1 140 1.4 0.01 54 6.0 R-116 83mm ~15YUBOB 6182475 0.1 88 73 4 23 15 737 2.80 1 1 6.5 0.6 180 2.2 0.14 48 7.7 R.117 83.3067 W15 390100 61- 0.1 84 33 4 40 9 972 1.85 2 10.0 2 2.2 120 3.1 0.01 28 7.7 R.118 8330689W15 3BMoo 61884M .. - - - ...... 1 ...... 0.01 26 7.8 R-119 -9 9W15 391668 8168849 0.3 44 63 2 51 17 684 3.20 1 1 3.5 0.1 50 0.9 0.01 26 7.7

R-120 awl0 w15 381668 6lsBgl9 02 44 61 1 51 17 642 3.25 1 1 3.5 0.2 50 0.9 0.01 m 7.8 n..m 833071 W15 378743 6187420 - .--. .. .. - .. - - 1 ...... - 0.01 m 7.8 833072 W15 375882 8187427 - -- --...... - - - 1 - ...... 0.01 28 7.6 WSAMPLENTSUM UM ~znCuWNI~hhF~.~woAsSbHpU Uh NO. NUMBER yll Mi. Norm- wm wmwm pvm ppn wm ppn X wm ppn m wm wb wm We-, (wb) lwbl lwb) R.124 839245 ww,s 37- 6,W__ __ ...... 0.01 38 8.0 R.125 -49 OW15 W953 6%- 0.1 67 58 2 41 15 745 3.25 2 1 3.5 0.6 100 1.7 0.17 28 7.6 R.128 833250 93N15 389269 6189553 0.1 49 58 1 35 14 467 2.70 1 1 1.5 0.1 70 1.2 0.04 30 7.0 R.127 831625 93415 386857 6197787 0.4 285 46 30 81 10 552 2.80 2 1 6.0 1.0 80 4.2 1.50 70 0.2 R.120 831026 93” 394851 6196210 0.1 57 58 1 58 24 BM) 3.M 1 1 1.5 02 30 1.5 0.04 46 1.7

R-129 831627 33M15 398721 61%725 0.2 ea 58 11 50 23 710 3.35 1 1 3.0 0.6 80 2.g 0.47 54 7.8 R.130 831620 93415 398721 6198725 02 ea 54 10 46 22 858 3.30 1 1 2.5 0.4 40 2.7 0.M 58 7.8 R.131 831629 83M15 403601 61- 0.1 34 15 5 18 6 241 1.50 1 1 1.5 0.3 10 5.0 0.20 58 7.3 R-132 831630 93M15 404553 6198636 0.2 58 35 11 34 13 740 2.65 1 1 2.5 0.2 50 7.4 2.24 70 7.8 R-133 831632 93M15 404580 6199298 0.1 16 7 1 2 2 3250 0.15 2 1 0.5 0.2 70 2.3 0.20 84 7.6

R-134 831833 93415 401061 mi72 0.1 30 14 3 17 7 187 1.25 1 1 1.5 0.2 m 8.2 0.21 M 7.3 R.135 031635 9W15 -16 6204688 0.1 25 10 2 13 5 105 1.05 1 1 1.0 0.1 20 6.0 0.12 72 8.4 R-138 031836 93M15 6206316 0.1 40 13 4 17 6 126 1.30 1 11.0 0.1 20 11.2 0.13 110 6.5 R-137 831537 93M15 399816 6x12962 0.2 53 32 9 35 15 490 2.30 1 1 3.5 0.1 30 2.2 0.53 52 7.9 R-138 831538 99415 398116 6201971 0.1 65 37 10 31 10 173 1.70 1 1 2.0 0.1 M 4.2 0.M 54 7.7

R-139 031639 93M15 391623 6200630 0.3 280 74 06 35 7 557 1.25 4 1 6.0 1.0 200 9.3 0.90 52 7.8 R-M 831640 83~15391275 6198840 0.2 74 23 16 5 204 0.50 3 1 3.5 0.2 1w 2.8 0.74 58 7.7 R-141 831642 93M15 391103 620355 0.9 980 40 437 56 16 IOW 2.05 3 1 10.0 2.0 900 2.0 0.20 30 7.8 R-142 631643 93M15 391103 6203155 1.0 1104 56 530 76 19 1180 310 4 t 9.5 2.4 13W 3.6 0.13 38 7.6 R.143 031044 93M15 380376 6205417 0.3 4W 72 18 72 20 710 2.90 4 1 5.5 0.6 170 5.6 0.59 80 7.5

R-144 831048 93M15 386486 6196529 0.1 76 04 1 61 31 1180 4.04 1 1 5.5 0.2 %I0.6 0.04 40 7.5 R-145 631850 93M15 389213 0195347 0.2 €6 65 1 41 26 616 4.20 1 1 1.5 0.1 00 0.6 0.04 32 7.2 R.146 831651 93M15 388341 6197572 0.3 165 51 33 54 10 286 1.85 1 1 3.0 0.2 100 0.5 0.70 54 7.2 R-147 831652 93M15 3B8M9 620X357 1.4 1200 115 30 MO 14 522 2.10 6 1 2.67.0 710 129.8 0.38 110 7.4 R-148 831853 93M15 387118 5205639 0.3 25 26 2 11 4 1.05198 3 1 2.5 0.1 120 11.7 0.03 58 7.3

R-149 631654 93M15 383744 62o6002 0.1 43 73 2 33 15 431 2.15 1 1 2.5 0.1 60 1.9 .. .. R.150 031655 93415 362026 -924 0.1 65 83 1 52 20 688 1.15 1 1 1.5 0.1 70 0.6 0.01 46 7.3 R-151 831656 93M15 383398 0205442 0.1 50 59 1 35 20 069 3.10 1 1 1.5 0.1 50 0.3 0.01 34 6.0 R-152 831657 93M15 382601 6202091 0.1 41 52 1 37 20 573 3.10 1 1 1.5 0.1 50 0.6 0.03 32 7.0 R-153 831858 93M15 378692 6201980 0.1 50 54 1 40 22 809 3.45 1 1 1.5 0.1 40 0.5 0.01 36 6.9

R-154 83i659 93M15 WXCa 6198552 0.1 52 58 I 43 22 635 3.25 1 1 1.5 0.1 40 0.8 0.02 30 7.0 A-155 833W 93M15 379580 61-7 0.1 42 43 1 38 23 578 3.30 1 1 1.0 0.1 50 0.4 0.01 40 7.1 R-W 831662 83~15377162 61s~~~0.1 48 58 1 23 15 so 2.90 1 1 3.0 0.1 80 1.4 0.01 38 7.7 R-157 831663 83M15 375973 6195118 0.4 63 134 3 47 17 807 3.40 2 1 5.0 0.6 2W 1.8 0.01 34 6.2 R-158 831W 93M15 380201 6196255 0.1 63 66 3 30 20 616 3.50 1 1 5.0 0.2 110 1.6 0.01 36 7.5

~-159 837665 03415 380888 61967~0.2 142 88 14 m 26 861 4.10 8 1 18.0 2.6 310 3.4 0.02 40 7.5 R.180 831866 83M15 380888 6196704 0.3 148 67 14 70 26 923 4.10 0 2 16.0 4.0 350 4.1 0.04 40 7.4 R-161 833246 93H15 3824026194479 0.1 72 65 3 40 16 771 3.20 1 2 3.5 0.7 1M 1.6 0.01 32 7.5 R.162 833247 93M15 W76188128 0.2 73 86 4 56 16 1oM 3.15 2 1 2.5 0.3 70 2.1 0.02 28 7.6

(0Hrmbmt. E. H.W. mm“cMi1l.n. W.1. (IW3J: Nationd Omshemid Rcconn~~un~cI:ZY)mOM~v~ti~~:Omlogic~SulvcyofCul~aDpcnRbl00l.

I35 (Appendix VI1 continued)

*o C" pb UI Mo Ni co M" " Th Sr Y m #d Sb s S. T.

Fpmppm Fpm ppm rn pp" "wm ppm 0.1 31 13 31 46 4a 2.8 0.8 0.4 0.1 I8 6 641. M 10 6.8 1.1 0.4 0.3 35 2.09 5540 4 m 6.5 0.5 0.3 0.3 0.4 6.3" n n n n n nnnnnn 0.1 39 10 n nn n nnnnnn 3.03 8637 48 6.7 0.7 0.3 , 0.3 02 3.0" n 0.1 19 2.11 5 17 38 38 5 18 02 0.3 02 02 2.4" n "" n 0 *On*""

02 M 57 28 5 3.1 0.2 0.3 02 0.2 2.2" n "" n n nnnnnn 0.1 28 58 29 5 3.8 0.4 0.3 0.2 0.2 2.7" n "" n n nnnnnn 02 IO 52 2. 20 62 0.3 0.4 0.2 0.2 ..E" n "" n n nnnnnn 0.1 26 55 32 m 132 0.7 0.5 0.4 0.3 5.8" n "" n n nnnnnn 02 13 57 20 5 1.5 02 0.2 0.2 02 2.2" n "" n n nnnnnn

0.1 8 221 18 13 5 0.4 02 0.4 02 02 t6n 0 o o n n nnnnnn 0.1 1. 0.88 31 12 5 0.4 02 0.2 02 0.3 ,.," n n n n n nnnnnn 0.1 38 3.55 88 38 m 11.5 0.e 0.2 1.8 0.3 7.6" n n n n n nnnnnn 0.1 2s 1.88 25 34 5 2.8 0.2 0.3 0.7 0.2 5.2" n "" n n nnnnnn 0.1 2.37 59 59 5 2.1 0.2 0.2 1.2 0.2 3.7" n "" n n nnnnnn

0.3 2.87 40 15 4 12.2 12 0.1 1.8 0.3 1.3" n n n n n nnnnnn 0.1 1.19 57II 12 5 3.8 0.. 0.4 0.2 0.2 3.0" n n n n n nnnnnn 0.1 0.38 8 13 7 3 5 OA 02 0.3 02 0.4 09n n n n n n nnnnnn 0.2 0.46 554 3 5 0.8 0.2 0.3 02 0.3 2.2" n n n n n nnnnnn 02 3.01 1 47 31 M 1.5 0.2 0.4 0.3 0.2 0.2" n "" n n nnnnnn

0.1 2.20 n 28 m 0.6 0.2 0.3 0.7 0.2 7.1" nnnnn nnnnnn 0.1 1.56 20 23 W 0.9 02 0.3 0.6 0.2 ,,,"n n n n n nnnnnn 0.1 2.88 48 35 W 2.0 02 0.3 0.3 02 1,.0 " n n n n n nnnnnn 0.3 1.86 38 33 rea 5 2 2 nn26.0 8.63 0.089 0 I8 1.48 100 0.- 13 0.6I 0.01 Om 2 02 0.811 P 23 280 I 2 25.2 10.92 0.055 3 8 5.76 ow 2 0.44 on1 0.02 2

0.2 3 0.76 51 17 340 P 2 40.7 14.93 0.061 3 8 8.55 78 0.01 6 0.37 0.01 0.03 2 0.1 9 2.72 58 20 ea 2 2 1.6 0.83 0.016 21 W 0.83 50 0.05 3 1.45 0.02 0.12 3 0.2 12 2.75 51 63 110 2 2 7.4 2.37 0.w9 6 38 1.a Ua 0.21 2 1.46 0.01 0.03 1 02 20 12 2.57 03 6 2 10.4 3.W0.058 10 30 1.91 288 0.13 8 1.22 0.01 0.03 1 0.4 53 12 2.m 270 10 2 13.8 ..37 0.0BT 8 40 2.% 642 0.10 13 0.09 0.01 0.M 1

3.0 4 720 1.a, 38 89J 15 6 22.1 lO.01 0226 8 12 5.35 $70 0.02 2 0.48 0.01 00) t 4.4 4 1 w, 1.88 35 750 12 2 21.6 8.97 0228 9 13 4.62 492 0.02 12 0.49 0.01 OM 1 0.6 68 836 3.59 21 00 5 2 11.3 1.880082 7 50 1.% 420 0.25 3 2.01 0.01 0.03 2 0.2 62 591 ..w 5133 80 2 5.0 ~700.0% 5 46 1.n Is 0.24 6 2.05 0.01 0.03 1 0.4 BO 880 5.15 5131 2m 2 8.4 110O.OM 6 48 1.18 14, 0.19 II 1.75 0.01 003 1

0.1 80 725 5.01 jm 2 10.7 1.M 0.050 8 50 1.42 II 0.22 11 2.50 0.01 0.w 1 0.3 30 837 2.39 160 2 8.2 2.07 0.082 0 3 1.38 527 0.13 3 1.13 0.01 0.05 1 0.1 18 2.4 11 ,W 2 2 7.8 OM0.058 31 14 0.- 128 0.01 0.78 0.01 0.07 1 0.8 . 58 2.00 32 150 2 2 12.7 327 0.0% 1, 24 2.01 log1 0.W 2 0.70 0.OI 0.W 1 0.8 70 3.46 38 250 2 2 8.0 1.05 0.109 12 m 0.88 1257 0.03 11 0.01 0.Ol 0.w 1

0.6 51 38 120 2 2 7.3 O.% 0.077 11 270.M 1281 0.03 4 0.67 0.01 0.05 I 0.1 20 26 00 2 2 4.0 0.36 0.W 23 IO 0.47 128 0.05 2 0.87 0.01 0.ll 1 0.1 19 360 16 13 2 2 6.5 0.w 0.OY 22 W 0.w u) 0.05 2 1.13 0.01 0.05 1 0.1 27 4c 2 2 5.6 0." 0.056 0.02 10 1.18 POI 0.03 1 a, ~ ~ 2! ~ 29 26 ~!.= (Appendix VU continued)

%mol. U" F. NO. ~ s45 s16 Sd? 1 0.1 548 1 0.1 S-48 1 0.1

2 0.2 1 02 1 0.1 1 0.1 1 02

5 0.3 1 0.2 1 0.2 1 02 1 02

1 0.6 3 2" n t 0.2 2 3" n 1 0.1 2 2" n 3 0.2 2 2" n 1 0.f 2 2" n

1 0.1 2 2" n 5 2.28 001 0.02 2 5 02 2 2" n 3 0.M 0.01 0.01 1 sa7 1 0.5 2 2" n 8 2 1.90 0.01 0.03 1 sa 1 0.1 2 2" n ,I 2 1.03 0.01 0.06 1 5.69 1 0.5 2 2"" 12 B 0.94 0.0, 008 I

S.70 4 0.4 2 2" n 3 0.w 0.0, 0.05 1 s-77 2 0.1 2 rn n 2 7.15 0.01 0.m 1 S-72 1 0.1 2 3" n 2 l.02 0.01 0.01 1 s-73 1 0.1 2 2" n 3 0.85 0.01 0.11 I S-71 1 02 2 2" n 4 0.77 0.0, 0.16 2

s75 1 02 2 2" n 3 0.57 001 0.00 2 9-16 2 0.1 2 2" " 2 0.59 0.0, 0.05 I s.n 1 0.1 2 2" n 3 0.- 0.01 001 2 4 0.3 2 2" n 6.8 2.02 (1.043 2 2.42 0.01 0.02 1 3 0.4 2 2" n 9.4 1.75 (1.015 2 2.59 0.01 0.02 1

2 0.7 2 2" " 8.7 1.0, 0.054 3 1.52 0.0, 0.03 2 I 0.4 2 2" n 8.0 129 0.037 2 2.33 0.01 0.02 1 1 0.4 2 2" n 7.0 0.54 0085 1 0.1 2 2" n 12.7 1.W 0.063 1 0.1 2 2" n 16.7 129 0.082

5.85 2 2" n 10.5 1.04 0.W sBB 2 2" " 6.3 029 0.077 2 2" n 5.9 0.35 0087 -sB, ~ APPENDIX VIII REGIONAL GEOCHEMICAL SURVEY; BULK STREAM SEDIMENT GEOCHEMISTRY FOR SAMPLES COLLECTED DURING THE YEARS 1987 AND 1988 -60+100 FRACTION - 1987 RGS

Mup Fiem UTM VIM ongma~ ~racd~n AY AD zn *I M MO NI crco na c. ~e tn ~a ss s. m u w L. c. sm EU yb LU II

-Numb.!- ~ NS!!X F*!CE.AB0-1!?% ~~.~ppm~Ppn~~E~pn~UPpm % PP”LW!XP pp”ppn Ppm ppn 51 MC87.HI-OI 4204156157518 5.m 21.07 45 d 400 4 1.3 <20 4W 24 3W Bw 15 4.67 5 1.2 35.1 QO 7 28 42 4 ZW 7.43Ll.l6.7414 124 do 0.2 ~~87.~102428508 61568% 6.lW 5.72 14m <5 400 4 1.3

04 MC8741-36 432118 6168129 5.m 7.76 13030 d 400 Q 4.2 <20 4W 17 160 27W 4 2.58 150 1.2 20.1 QO 10 13~215 980 2570 3570 380 8.4 28.1 4.81 do 0-7MC87-HI47 425293 6182162 6.700 7.70 1sWm d 400 46 3 <20 Mo 19 270 3300 6 3.82 78 0.92 33.8 QO P no 38.3 5m 783 1020 s.3 10.1 10.4 1.3 do 04 MCBI-HIM 434218 6160561 6.W 7.88 43 <5

0-11 MC87.HI-11 412889 6171381 5.m 10.22 QB d 400 4 4.9 <20 4 110 19W 16 3.38 60 0.37 21.4 40 10 270 58.9 35 121 866 87.7 12 17.5 2.82 do 0-12 MC87-H1.12 412742 81713W 6.7W 5.34 INT d INT INT 6.0 IM IM INT IM IM IM 2.85 1W 4.26 15.1 IM IM 1700 205 IM 8810 (Km a 482 18 6.91 do 0.13 “7-Hl-13 419182 6155891 6.W 11.77 1Km 6 700 27 0.3 <20 19 290 12W 6 4.62 4 0.47 24.6 40 35 270 54.3 3200 727 log0 99.7 11.6 20 3.53 do 0.14 MC87-HI-14 41W 6153910 6.m 3.26 Q3 d 400 d 4.9 UO IM 12 250 9 3.91 4 0.45 23.6 40 27 zy) 68.9 240 518824 106 17.434.3 4.48 60 514 MC87.Hl-14a 41- 6153910 5.m 3.26 M 6 2w Q 0.8 <20 24K4 11W 7SW 400 4 37.9 4.4.05 39 40 4 1 22 4 50 47 5.9 22 2.9 0.44 do

0-15 MC87-H1-15 417CU3 615W 7.m 7.80 IKT d Bw P 4.2 c30 W 12 M INT 10 l.A 4W 0.49 18.9 40 30 410 140 SV 479 589 120 25.748.4 6.42 do 0-16 MC87-HI-17 433346 6175878 5.4w 7.92 INT d 3w <4 d.4 -SU dW 6 40 7100 Q 0.77 88 INT 4.6 QO 4 ew 5n IM 7420 ~ylo7.55 20.9 P.? 5.n QO 517 MC87-H1.16 426281 617S315 6.m 4.19 e5 d 400 4 46 ~20QW 10 4W 8100 4 1.05 <4 ~4.6 9.1 QO 9 12w 607 IM 72W 8811) 810 810 42.921.5 do 0.18 ~037.~1.19 4229227 6175106 7.m 6.44 d d IM IM IM a 4W 23 IM UOO do INT 210 IM 3.9 INT 4 4203 IM 711 8330 177.55 47.3 8.80 do 0-19 MC87-H1-21 40- 6176810 5.m 3.72 d 6 400 Q 4.2 a 900 4 80 49W 4 0.91 89 0.31 13.4 40 a, 1900167 IM 4590 sir, 591 42.7 28 3.46 do

0.20 MC87.Hl-25 423375 6178850 7.m 5.56 IM 6 7W 380 IM <20 IM <17 130 INT D 0.94 1M IM 8.3 120 415503 LUI IM 103m 11Sm 1050 30.6 34.19.68 do s.z~~87:n1.26 418~50616- 5.100 6.02 47 d 400 8 4.9 11 ~7w10 332

4.76 880 6 dm <7 ~0.6do <4W 13 180 6W <6 3.27 120 0.92 30.6 QO 45 1W 27.1 190 402 553 472 11.1 17 2.1 40 8-3 MC67-H1Q3 424071 5153362 5.7W 4.42 3800 6 aM 30 4.7 QO r5W 15 240 3w3 2% 295 UO 1.1 30.6 30 6 820 104 BB 2430 3380 254 26.6 20 3.11 ~50 8d MC87-H1-M 433283 6153514 5.4.20 11.80 190 c5 200 11 2.4 QO 8W 16 3R1 37W 12 4.74 52 1.1 39.6 QO 8 210 36.3 68316 1mO 93.6 10 11 1.97 <50 8-5 ~~87.~1-05*351m 615%~ 5.m 10.74 INT 4 4W 40 <2.3 do IM 23 ea IM QC 1.44 440 0.23 14.6 80 25 780 136 IM 2710 2990 241 23.1 U.2 5.94 ~50

6-6 MC67-H1Q8 432416 6168129 5.m 6.05 480 6 cm, <13 <1.6 do am‘14 a 3~x)<13 1.84 1m 1.2 18 QO B 620 107 49 1410 18~1184 12.7 11.3 2.21 ea 07 MC67H147 125290 61621W 67W 6.15 16mm 4 dm 47 4.2 QO 4W 13 180 1300 10 2.04 180 0.67 26.1 40 20 330 54.2 270 1180 1550 1W 17.4 35.4 3.04 <50 6-8 MC67M08 W16 6180561 6.W 14.12 <19 c5 dm 4 1 40 400 <5 IW 7w 10 1.56 ea 1.2 14.4 40 16 130 44.3 BB 395 639 m.9 6.1 13.8 2.83 eo 84 MC87-Hl-09 412397 6162704 4.m 9.93 13000 <5 dm 4 1.4 40 4W 22 170 8W 6 3.55 4 1 25.1 QC 11 200 15.8 240 638 11m 84.5 6.3 16.1 1.49 ~50 8-10 ~~87.~1-10mm 6wa1 6.200 5.97 Xm 4 dm Q 2 do 6W 35 Po 21W 4 2.56 170 1.1 41.5 d0 33 530 W.4 260 2180 2490 155 17 P 2.97 60

8-11 MC67-H1.11 412969 6171381 5.m 9.02 INT 6 dm 40 42dO 43(4 41 <40 IM 40 1.68 120 0.75 15 40 13 320 60.7 27 1110 tu0 123 16.19.22.4 <50 8-12 MC67-H1.12 4127426171390 6.700 2.71 INT d dm IM <0.2 QO dW 41 300 36W INT 2s 330 IM 12.4 QO 20 1m 316 INT 7380 8090 622 34.3 35.5 5.71 -53 8-12 MC67-H1-128 4127426171390 6.7W 2.71 490 e5 1Bm 940 620 40 2Wm 930 6100 r5W (1 32.5 <1 0.1 29.7 30 4 1.3 3 <4 39 25 3.3 22 21 0.23 <50 6-13 MC67-H1-13 419162 6155691 6.W 4.18 1 woo 4 2W 34 e1.5 90 <2W 14 250 1200 <7 3.26 13(1 4.05 21.4 <20 33 470 % 2Wl6W 2m 116 14 16.7 2.16 40 8-14MC87H1-14 417068 6153910 6.W 1.91 <57 4 QW 16 1.9 40 4W 13 180 16W INT 3.37 190 1 21.3 QO 30 370 66.6 320 1130 1090 112 15.5 31.6 5.54 a

8-15 MC67-HI-15 4170836153846 7.W 11.Y) 480 r5 &X 6 0.5 QO <4W 10 80 14W 14 1.85 280 2 16.2 QO 20 250 103 150 384 €69 93.2 14.738.3 7.34 ~50 8-16 MC67-HI-17 433348 6175676 5.400 4.42 29W 4 Qm IM INTINT QW IM INT 1WW INT INT ‘1 0.54 4.9 eo INT 4200 4% IM 7550 8880 877 67.6 27.1 3.13 <50 6-17 MC67-HI-16 429281 6175315 6.2W 6.08 c1W c5

6-20 MC67-H1-25 4233756176950 7.m 6.32 470 6 200 IM ~3.3do INT 66 ‘90 SW 54 INT 180 0.95 4.1 40 4 24w 382 INT 8420 7uO 626 25.6 283 6.61 6-21 MC87H1-26 419250 6167680 5.100 3.67 <49 <5 <303 11 r1.2 40 dm 43 ‘50 410 41 <20 15 220 792 140 923 998 93.9 13.9 14.62.7 ~50 ”- ~ ~~ 175 ,1-30336:7 a. demea sample re.analpis -200 Fraction - 1987 RGS

Sb Ni CO Fe HI Na ss st, m u Sm Eu yb Lu 1, % % Ppm pp" Ppn ~~ ~ Ppm ~~~ Ppn ~ ppb ppm wm ppm Ppm ppn~. ~ ppn ppm 2.4 14 3.07 66 1.2 25.1 Qo 28 4.1 19 8.1 5.3 0.89 do 4.8 do 11 dW 1.68 180 1.1 13.8 81 18.5 30.8 5.2 9.8 1.3 do 4.1 40 18 <8W 1.82 92 1.1 14.8 170 31.8 80 8.3 8 1.88 do 1.2 40 18 1300 3.41 <1 1.1 212 140 21.5 56.2 7.4 8.8 1.B do 4.6 00 13 1303 1.5 540 1.4 17 440 120 83.8 18 19 328 do

1.8 do 9 11W 1.91 130 1.5 10.4 270 77.4 21 162 11.5 13.5 2.89 do r1.5 00 47 Ism 224 2.M 2.3 162 Zen 64.3 54 93.4 9.8 12.1 2.32 do 70 do 10 8W 4.52 0 0.11 12.5 5.7 5

2 QO 42 3700 2.66 330 2.8 16.5 780 119 33 281 31.9 59.9 10.9 do 41 QO '10 1Sm 2.85 110 2.5 18.1 170 24.8 m 57.5 7.3 13.2 3.w M 4.5 QO 8 4w 0.61 180 2 7.8 81 25.3 12 28.1 6.4 13.4 2.21 do Q.7 QO <17 5x0 1.98 300 1.6 9.7 1700 285 78 518 u2 24 5.81 do 44 -30 47 2800 1.24 190 2 5.4 440 71.2 45 145 9.8 19.9 *do

Q.8 do 3700

M .0 SAMPLE M.0 UTMUTM HMS M SAMPLE Au B Ce CI Eu LL Sb Sc Sm Ta m U W Y ZI No. NUMBER Earlhg Nomlw -A!! w.m Ppb ppn Ppm ppn Ppm Ppm Ppm m Ppnm Bm ppnppn ppnppn 822 Ma-H1-01 397528 6178309 20.59 m 82 770 380 38M -2 0.867.1 6.2 27.0 8 4.0 8.6 9 5 24W 8 23 Ma-H1-02823 401509 816W 24.74 1.75w 15 570190 1490 150 1.5 73.9 99.0 83 203.0 62.8 28 28 3100 393190 8173561 17.75 3y) .14 -lw 88 12W 6 0.5 2.2 82.2 11.0 2 5.8 1.2 d5 393258 6174188 58.90 380 35 .lw 120 750 4 0.5 2.0 65.1 12.0 2 2.8 0.5 4.s 284341 6175388 57.w 5w 300 140 33 17W -2 0.5 1.5 88.6 5.3 2 2.6 0.5 45

M16175388 -9.W 42 -lw 23 1500 -2 0.5 1.4 91.1 4.5 1 2.1 1.2 55 378918 6173602 88.80 550 -5 290 28 17W -2 0.5 0.8 111.0 4.3 .l 1.6 0.5 -7 5 378916 6173602 .9.W -11 180 -10 1500 -2 0.5 1.1 97.8 42 .l 1.1 0.5 -5 5 390523 6168859 58.83 360 180 140 1260 810 10 0.8 2.5 74.0 n.8 25 205.0 40.0 180 13 380880 6169503 88.86 360 -5 .1W 2790 -50 34 4.3 1.6 90.1 213.0 73 388.0 107.0 wu 39m 8169503 -9.w -19 -m 2340 430 29 0.6 0.9 81.7 14.0 67 371.0 85.0 vu 397467 8171859 32.62 m 16 250 1440 BIO 9 0.6 4.3 53.1 72.3 21 2020 34.0 339 12 382210 6171431 21.29 1W Ism -100 1310 em 10 0.6 5.0 67.2 59.7 17 171.0 24.0 238 13 378214 6176922 108.05 5w -13 -lW -10 2m 2 0.5 1.0 122.0 5.0 1 2.1 0.5 4 -5 378214 6116922 .9.W -12 -lW 22 2m -2 -0.5 0.9 119.0 4.9 .1 2.9 0.9 -13 5

378214 6176922 152.12 550 -19 .240 31 2900 .2 0.5 1.3 140.0 4.7 .1 1.9 1 .8 -15 5 376214 6176922 -9.W .20 -1w .P 2800 3 0.5 1.0 134.0 5.2 1 2.5 0.5 49 -5 378214 6176922 .9.W 31 -100 24 2700 .2 0.5 1.2 125.0 4.6 .1 22 1.8 48 -5 391133 6166983 14.70 250 -13 290 -50 26 0.9 1.0 u.0 191.0 78 5al.O 121.0 .21 38 393188 6180708 29.73 280 .14 -lW .e483 12W -2 0.5 3.7 74.6 11.0 -1 0.5 68 3.6

390134 6188819 33.31 -18 690 82 1500 -5 0.7 3.3 65.2 10.0 2 5.6 0.5 4 .5 368442 6188159 1M.U 850 -19 250 n 1500 2 0.5 1.7 58.4 13.0 1 8.5 0.5 .23 .5 388442 6188159 -9.w 230 190 80 l9W 3 0.5 1.8 60.1 120 2 10.0 2.5 -250 -6 388442 6188159 97.65 550 772 310 rw 2403 4 0.8 2.4 83.4 11.0 2 12.0 -52.7 -12 38w 8188159 4.w -17 .1W 78 2m 4 0.5 2.1 85.5 11.0 2 6.8 1.6 -18 5

18.04 em 110 990 54 12W d .0.5 4.2 W.6 10.0 .1 6.4 0.6 327 37M 610 .5 250 190 1MO 4 0.5 . 2.7 95.5 15.0 4 23.0 3.8 -7 5 85.31 55(1 .5 110 34 lBw -2 -0.5 . 1.5 88.1 5.6 .1 1.9 .5 0.5 .10 376714 6187107 97.98 750 -10 310 21 1403 3 -0.5 2.0 1W.O 6.1 1 2.8 0.5 4 -5 376714 6187107 .9.W .ll 250 30 1100 -2 -0.5 1.7 83.5 5.3 -1 2.5 0.8 .ll -5

388842 6164585 20.79 280 .19 -1w 2880 4% 47 0.5 1.1 55.4 188.0 65 570.0 118.0 4 61 383236 6162322 20.23 5w 253 -lw 110 1403 4 0.7 2.9 65.8 14.0 2 5.6 2.6 56 393057 6162210 40.90 370 -6 380 83 1Bw 3 0.5 2.6 85.3 10.0 3 5.1 2.5 -7 8 396704 6167339 49.35 m -10 310 42 870 3 0.5 0.9 79.3 7.6 -1 2.0 0.5 45 396704 6187338 72.30 430 -1 1 250 32 730 3 0.7 0.6 77.4 7.5 -1 21 0.5 4 5

398704 6187338 -9.w -12 240 33 830 -2 0.5 0.7 62.3 6.6 1 28 0.5 5 -5 397993 6183968 40.99 520 24 -1 W 270 3600 2 0.5 2.6 87.8 19.0 6 38.0 6.9 -10 -5 398773 6184749 22.01 300 -16 .230 gP 17W 4 2.2 1.3 72.3 85.2 6 231.0 29.0 .7 12 0d7 Ma-H1-26 6184749398773 88.88 550 d 390 m 990 4 0.6 1.5 73.6 10.0 2 6.7 15 -7 -5 0d7 MCW-Hl-ZM 400380 619W9 -9.04 -5 480 67 1ma 3 0.5 1.1 67.3 9.0 2 7.7 1.8 8 .5 848 Ma-H1-27 40214% 618856719.00 30- -13 740 1mo d 1.9 61.4 73.8 8 188.0 27.0 9 12 ~ .PO ~ ~ ~2..______- 1988 RGS BULK SAMPLES (-80+170 Fraction, May 8, 1990)

Map Fmld urn UTM HMSW SAMPLE AU ss ce CI EU LU sb sz sm TS m u w Y zr aNo Number Ea*w Nonhvl m. m ~pb

822 MWH141 397526 6176309 28.37 7- 562 740 380 3803 4 0.9 5.6 75.1 26.0 5 38.0 10.0 5 823 MCWHIUZ 401S9 6165CW 21.02 313 79 .m 1130 8zD 12 2.8 1.4 88.3 86.8 39 185.0 712 28 8-24 MWH103 393190 6173% 10.69 83 150 .1W 160 1300 3 4.5 2.1 €8.9 12.0 2 5.6 1.8 -5 825 MWHIOI 393258 6174198 4.83 87 24 .250 130 1500 -2 -0.5 1.7 M.0 10.0 2 8.3 3.6 5 8-26 MWH1.05 384361 6175398 21.12 192 97 .1W 71 1300 .2 4.5 1.5 90.0 8.1 2 6.5 1.8 7 E27 MCWH106 378916 6173802 30.66 171 88 -lw 34 1500 -2 .0.6 1.6 90.8 5.7 1 2.9 0.6 5 828 MCWH147 380523 6169859 30.70 133 1w 330 em 1m 9 4.5 2.6 66.6 45.0 23 158.0 65.0 43% 829 MCBBH108 880560 8169523 17.05 1m ?4 -m 1230 e40 12 2.1 12 70.2 101.0 33 238.0 142.0 338 830 MWHlOg 387467 6171859 7.24 76937 .280 no 1200 9 4.5 3.1 46.0 U.0 13 137.0 63.6 M 831 MCBBH1.10 382210 6171431 4.62 55 1810 .300 720 11W 8 4.5 3.3 51.0 88.0 11 103.0 38.0 190 832 MWH1.11 378214 6176922 U.88 22s 250 .1W 36 2m -2 4.5 1.1 124.0 6.3 2 5.1 22 -11 832 MWH2.11 376214 6176927 46.92 214 629 .1W 35 29m -2 4.5 1.3 104.0 6.6 2 4.7 2.1 -11 833 MWHl.I2 391133 6166983 8.11 87 12m .?a0 2210 6w 15 2.0 1.2 m.4 128.0 47 a0 112.0 35 834 MWH1.13 393196 61W708 9.47 7028 a0 130 1500 -2 0.6 2.775.8 13.0 -1 5.7 32 4 0.35 MCBBH1.14 390134 .6166619 19.45 213 210 520 130 1pm 5 a5 3.5 67.7 13.0 . 2 6.2 -12 -10 838 MWH1.16 38W2 6188159 29.50 155 120 -m 110 2100 -6 0.6 2.767.9 15.0 2 12.0 2.8 5 036 MWHZ.15 38W2 6188159 24.79 146 48 230 120 2m 5 0.5 1.9 712 15.0 2 16.0 3.7 a 837 MWH1.16 380056 61W7 6.97 275 24 1500 60 660 -2 .0.5 3.7 26.0 8.7 1 7.3 3.2 24 03a MWH1-17 394806 6177307 22.92 230 15 .1w 170 990 -2 0.7 2.0 72.9 16.0 2 16.0 3.6 -5 839 MWH1.18 881810 6188716 29.48 122 280 -lw 32 2300 -2 0.7 1.6 67.3 6.0 1 3.9 .0.5 5 E40 MWH1-19 376714 6167107 27.51 143 24 590 41 1W -2 4.5 2.1 85.0 5.9 1 2.7 1 A -13 541 MWHl-20 388812 6164555 6.87 80 370 .300 2320 260 17 2.7 4.2 a.1 165.0 39 460.0 108.0 28 542 MWHl-21 383236 6182322 9.34 1m 220 180 160 1400 4 0.9 2.7 55.2 16.0 2 6.6 3.7 5 E43 MWH1"Z 383057 6182210 14.08 85 210 €60 93 Ism .2 4.5 2.3 60.6 10.0 3 5.6 3.0 -5 544 MCBB-HI-23 396704 6187338 9.02 88 17 BBO 53 no .2 4.6 1.0 51.9 8.3 -1 1.7 1 .O -5 044 MWH243 398704 6167338 12.60 128 .18 570 48 670 -2 0.6 1.0 535 I7 .1 -12 1.3 5 E45 MCBBH1-24 397993 8183988 13.87 IW in -260 310 2700 .2 1.0 2.4 57.7 21.0 5 88.0 7.7 17 546 MWHI.ZS 388773 611y7.m 8.42 71 .19 .1w Zwn 1500 11 4.5 1.3 M.8 219.0 13 760.0 89.6 -16 847 MC88-H1-28 4o0980 6192649 3.42 255 -17 7w 76 11W 4 0.7 1.1 37.0 8.5 1 110 3.1 .5 546 WH1.27 402140 6188567 8.59 141 20 250 1440 950 7 -0.5 1.1 51.2 135.0 12 4Q5.0 61.3 .11 25 2300 1988 RGS BULK SAMPLES (-170 Fraction, May 9,1990)

NUMBER N0ml"p gnWpm. ppb ppnppm ppn______- wm m m PPn m mmm Pp" MCBB-HI-Ol 6176309 7.48 808350 1Mo 5 0.7 2.7 21.0 11.0 -1 17.0 6.7 8 .5 .18W MW-H102 401509 6185080 4.66 88 420 no a 4.2 1.0 35.0 39.0 19 116.0 85.1 a 20 B(KD MCBB-Hl03 393190 6173561 0.45 35 85 14W -10 -2.5 1.3 58.0 190 -5 19.0 7.2 -10 -25 5300 MCBB-H104 393256 6174188 1.M 41 150 970 a 0.5 2.2 50.1 11.0 2 3.9 4.1 -10 -5 -2800 Ma-HI05 381381 6175398 4.79 1m 470 11W -2 0.5 1.1 75.2 8.6 1 72 3.0 4 -5 -1201 MCBB-H1OB 378918 6173802 3.69 63440 1m 5 0.5 1.4 83.1 6.2 2 3.5 3.1 .18Wa -5

MW-Hl07 380523 6169859 7.24 51 2660 750 6 8.4 2.0 56.2 35.0 15 129.0 88.9 231 MCBB-Hl08 380880 61eOYa 4.25 31 819 -140 -7 11.0 1.3 58.8 51.0 17 174.0 173.0 242 MCBB-H1-M) 387467 6171859 1.48 45 1m 970 -9 2.3 2.8~~~ 48.0 ~~ 35.0 10 11RO 71.4 130 MCBB-HI-10 382210 6171431 0.89 38 ioso 900 .10 -1.0 2.3 33.0 26.0 10 82.0 55.0 110 MCBB-HI-11 376214 6176922 2.M 106 562 .?coo 4 1.0 13 480 6.7 .1 72 5.5 8

MC88-H2.11 376214 6176922 12.37 124 210 2x4 .2 0.5 1.0 61.5 6.6 1 5.8 3.8 -5 -5 -1200 MC88-Hl-12 391133 6188983 I .a 48 949 -210 .13 4.8 1.3 41.0 82.7 40 278.0 185.0 W 38 3mm MC88-HI-13 393198 6180708 1.31 41 2630 1200 .7 0.5 2.6 55.8 14.0 -1 6.6 3.2 14 13 3800 MC88-Hl.14 3SV131 6166619 2.43 107 52 1500 4 0.8 1.8 47.0 14.0 2 16.0 7.9 a 6 .21W MCWH1-15 3m2 6188159 2.09 788 79 2100 5 0.9 1.9 41.0 16.0 -1 PO 12.0 12 10 31W MC88-HZ-15 3B8M2 6188159 1.05 82 320 22-30 a 1.0 2.3 29.0 17.0 3 29.0 10.0 -9 -5 -2Mo

MW-H1-16 390058 6186637 0.25 1M 1W 480 .10 -2.5 4.7 P.0 6.4 -5 d.6 -2.5 -28 MC88.Hl-17 394808 6177307 2.1 1 114 80 850 6 0.6 1.5 42.0 10.0 .1 11.0 5.0 -5 MC88-HI-18 381840 6188716 4.51 51 14 19W -2 0.5 1~4~~~ 68.8~~ ~ 9.2 2 10.0 5.8 5 MC88-HI-19 376714 6187107 1.06 50 -24 1700 -5 0.5 3.6 38.0 6.5 2 5.8 4.3 -8 MC88-H1.20 388w 6161585 1.35 305w -240 .15 6.4 1.2 55.8 115.0 23 412.0 171.0 40

MCBB-HtQI 383238 6182322 2.25 67 745 1Mo -5 1.0 2.1 48.0 19.0 3 13.0 6.9 a MC88-H1-22 383057 6182210 1.55 38 882 22-30 -5 0.5 2.0 37.0 8.2 3 10.0 7.3 .7 Ma-H1.23 398704 6187338 1.80 43 130 770 x5 0.7 1.0 48.0 10.0 -1 5.8 2.7 -7 MCBB-H2.23 6167338 4.61 53 516 61 0 .2 0.7 1.0 54.9 8.7 1 3.9 1 .9 a MW-H1-24 6183988 2.79 36 250 2100 5 0.8 2.1 37.0 25.0 5 48.0 21 0 25 MC88.Hl-25 61lu749 1.72 28 219 460 -25 15.0 7.6 32.0 435.0 20 1m.o 212.0 -16 MC88-H1-26 6152619 1.29 147 1430 420 8 0.5 0.8 22.0 7.4 -2 14.0 5.3 -10 MCBBW-27 6188567 1.54 781 ~ 13.0 0.6 ~ ~ 40 -290 .20 __ "0 9 188.0 -13 " ~ 328.0 990.0 ~__~ ~ ~ APPENDIX Iji REGIONAL GEOCHEMICAL SURVEY; MOSS-MAT GEOCHEMISTRY FOR SAMPLES COLLECTED DURING THE 1989 FIELD SEASON A" n0 CuPbZnNiCoAsMnMo Fe UTbSrCdSeVCa PLaCrhlg ea n BGeSsTe U Na K W Hp LO1 %Ppm@ % Ppb Ppn Ppm DPoppm?!rn%F.FXpp"~ppm-b_E!?~~E~PpnPpm E!! x 2LE!Lppn-1( -Ppn~- ~~ %PpmppnPpmFm % -% 20 02 32 11 84 169 17 15.2 7Z3 1 3.54 5 1 56 1 4.7 0.6 45 1.5 0.09 12 104 1.6 152 0.1 5 02 0.2 0.3 1 0 0.1 1 n n 11 0.1 35 17 91 17179 15.6 759 1 3.44 6 1 81 1 5.1 0.6 41 1.5 0.09 12 106 1.8 tea 0.1 11 02 0.5 0.3 1 0 0.1 1 n n 9 0.1 17 11 40 15 6 2.6 379 1 1.59 5 5 34 1 2.3 0.1 38 0.9 0.24 32 23 0.5 % 0.1 2 0.3 0.2 0.3 1.1 0 0.1 1 n n 1 0.2 67 2 94 19 8 14.9 885 1 2.76 5 1 99 1 4.2 0.6 51 3.3 0.13 7 31 0.7 142 0.1 17 0.2 2.9 0.6 1.3 0 0.1 1 n n 2 0.2 2 53 9 81 39 13 6.3 en 1 4.27 5 1 80 1 3.4 0.3 101 2.5 0.09 10 30 1 85 0.3 10 0.4 0.7 0.3 2.2 0 0.1 1 n 0 1 0.1 86 2 76 28 12 5.7 BBB 1 3.6 6 1 84 1 2.8 0.1 97 1.4 0.08 8 51 1.1 119 0.1 9 02 0.3 0.3 2.1 0 0.1 1 n n

1 0.1 56 10 99 46 14 5.7 561 1 4 5 1 67 1 3.1 0.1 1GZ 1.6 0.1 6 % 11 78 0.1 14 02 0.5 0.3 1.6 0 0.1 1 " n 520 0.1 16 8 41 14 ? 3 X6 1 2.46 5 7 32 1 2.1 570.4 0.9 0.21 35 38 0.5 W 0.1 2 0.2 0.2 0.3 0.9 0 0.1 5 n n 1 0.1 8 10 36 10 5 2 219 1 1.83 5 11 46 1 1.4 0.6 32 2 0.85 46 19 0.5 m 0.1 4 0.2 0.2 0.3 0.6 00220" n

2.~ 0.4 70 16 126 37 18 22.8 727 2 4.46 5 2 38 2 2.7 0.3 98 0.9 0.12 9 58 1.2 59 0.1 2~ 02 ~~ 1.9 0.3~~ 7.8 ~ 0 0.2 2 n n 1090 0.1 17 12 70 16 6 6.2 342 1 3.71 6 9 56 1 1.4 0.5 75 1.7 0.83 46 38 0.8 111 0.1 7 0.2 02 0.3 12 00222" n 1 0.1 52 13 E4 40 11 5.2 4C6 12.98 5 1 84 12.90.3 60 1.8 0.1 6 66 1.1 66 0.1 20 02 0.8 0.5 1.4 0 0.1 1 n " 1 0.1 E4 3 80 42 11 5 431 1 3.07 6 1 82 1 2.4 0.4 94 1.7 0.08 5 72 1.1 57 0.1 15 0.5 1 0.6 1.4 0 0.1 1 n n 167 0.1 11 4 80 10 5 2.7 4W 1 2.72 5 4 61 1 1.1 02 45 22 1.01 66 16 0.4 14 0 2 02 0.2 0.3 0.9 0 0.2 2 n n 47 0.3 E4 15 % 35 13 15.7 631 1 3.74 6 1 51 1 4.7 0.4 61 1.3 0.08 8 43 1.1 ea 0.2 7 0.4 1.7 0.3 1.7 0 0.1 1 n n 42 0.2 37 14 €8 37 IO 7.9 By) 1 2.95 6 1 51 1 2.5 0.1 61 1.8 0.08 6 46 0.8 97 0.1 10 0.2 0.4 0.3 1.1 0 0.1 1 n n

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as 0.7 65 13 375 ea 14 13 o* 8~ 3.40 ~~ 5 2 80 2 2 2 42 1.17 0.116 17 27 0.93 1373 0.1 2 n n n 1.03 0 10.07 W~~ 80 ~~ 2 0.4 52 23 108 Ill 13 9728 8 2.85 5 149 2 2 3 38 1.12 0.080 12 28 0.81 1358 0 10 n " n 0.97 0 0.07 2 110 14.0 1 0.1 20 12 83 27 9 3303 1 2.71 5 10 20 1 2 2 45 0.44 0.082 39 26 0.52 0.1108 21 n n n 1.08 0 0.12 6 30 5.1

9 0.1 17 13 61 28 9 33.2 1 2.25 5 6 15 1 2 2 16 0.330.087 28 21 0.50 39 0 12 n n n 1.W o 0.08 1 20 102 1 0.1 25 15 72 34 12 6 457 1 3.18 7 728 1 2 2 w 0.53 0.079 a 29 0.73 52 0 2" n 01.43 0 0.M 1 30 12.1 8 0.1 w 7 74 29 13 2245 1 5.61 5 12 85 t 2 2 97 1.40 0.114 52 35 0.76 128 0 2 n n n 1.16 0 0.M 1 40 7.0 1 0.1 18 5 89 25 11 2403 1 3.28 5 759 I 2 2 28 1.14 0.081 41 20 0.50 133 0 2 n n n 1.01 0 0.13 1 34 10.5 i 0.2 44 40 137 43 14 6% 3 4.21 5 243 1 2 2 ?a 1.91 0.078 12 43 1.36 i1w 0.2 6 n n n 1.55 0 0.08 2 80 8.5

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1 0.1 24 17 90 37 2 1087 1 3.21 5772 1 2 2 W 1.790.078 39 29 0.97 110 0.1 2 n n n 1.11 0 0.19 1 40 12.3 1 0.1 87 9 83 51 17 2880 1 4.m 5118 1 2 2 118 2.39 0.054 5 74 1.52 221 0.4 2 n n n 2.99 0 0.08 1 50 122 2 0.1 80 9 88 35 15 5 871 1 3.44 5125 1 2 21042.110.018 4 52 129 143 0.4 2 n n n 2.59 0 0.11 1 40 27.1 2 0.1 44 16 71 34 17 2 1086 1 3.91 5119 1 2 2 1P 1.94 0.080 5 58 1.28 240 0.4 11 n n n 2.72 0 0.04 2 40 14.0 2 0.1 35 5 56 m 14 2 Y1 1 3.34 5112 1 2 2 118 1.95 0.039 3 27 1.14 190 0.5 14 n n n 2.18 0 0.W 1 20 4.5

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1 0.8 71 65 1043 275 15 20588 18 3.18 5 1 71 6 8 2 49 0.88 0.m 11 28 0.m 1x6 0.1, 3 n n n 0.97 0 0.08 1 180 12.0 2 0.3 61 72 102 U 15 3646 1 3.39 5 140 1 2 2 75 1.58 0.047 5 42 1.47 1247 0.3 2 n n n 1.87 0 0.04 1 60 7.8 1 0.5 51 35 491 58 12 9 819 3 2.n 5 130 3 2 2 n 2.23 o.mi 9 46 1.53 724 0.1 4 n n n 1.28 0 0.08 1 120 14.6 2 0.5 38 49 704 E4 12 7 1157 2 2.n 5 134 5 2 2 55 2.93 0.171 12 40 1.83 862 0.1 5 n " n 121 0 0.08 1 1W 17.4 5 0.4 47 31 149 40 9 17 44 x) 2.55 5 257 1 5 2 63 1.32 0.085 11 22 0.82 1052 0.1 2 n n " 0.82 o 0.08 2 70 7.9

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“94 MCB9M1-73 378038 8214963 1 0.2 78 14 109 52 16 7 648 1 4.22 5 1 31 1 2 2 95 1.35 0.08712 95 1.14 575 02 2 n n n 2.51 0 0.08 1 70 19.3 M95 MC89M1-74 378252 621- 1 0.3 60 29 283 81 15 12 826 8 3.48 5 1 52 3 2 2 57 1.01 0.055 9 47 1.m 1427 02 2 n n n 1.49 0 0.01 1110 8.5 M% MC84M1-75 4Cd591 820901J4 1 0.1 11 4 39 215 7 203 1 1.28 5 9 15 1 2 2 14 0.35 0.104 37 15 0.29 151 0.1 11 n n n 0.73 0 0.20 1 20 9.0

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