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Stratigraphy, maturation and source rock potential of cretaceous strata in the Chilcotin-Nechako region… Hunt, Julie A. 1992

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STRATIGRAPHY, MATURATION AND SOURCE ROCK POTENTIAL OF CRETACEOUS STRATA IN THE CHILCOTIN-NECHAKO REGION OF BRITISH COLUMBIA  by JULIE A. HUNT B.Sc., University of British Columbia, 1989 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL SCIENCES We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA January, 1992 © Julie A. Hunt, 1992  In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.  (Signature)  Department of  ^601.0 if $)-)1_^gAiCeS  The University of British Columbia Vancouver, Canada  Date  ^  DE-6 (2/88)  nun  ) ( )  4A\  )  1 °7 '2  ii ABSTRACT  The Chilcotin-Nechako region lies within the Intermontane Belt of British Columbia on the western edge of Stikinia and includes the Tyaughton Basin. Exposed within the region are Early Albian to Cenomanian sediments of the Skeena, Taylor Creek, Jackass Mountain and Battlement Ridge groups plus unnamed sediments of similar age and lithology. These sediments were deposited in one large, initially marine, basin (Nazko Basin) and are separated from older sediments by a major hiatus (Barremian to Aptian in the south and Berriasian to Valanginian in the north). Marine conditions persisted in the northern ChilcotinNechako region until at least Cenomanian time, and until the Maastrichtian in the central Chilcotin-Nechako region. In southern Chilcotin-Nechako region, marine conditions ceased in mid Albian time with the deposition of the Silverquick formation. Latest Albian - Cenomanian time marks the transition from a dominantly sedimentary to volcanic province. Volcanism was widespread throughout the Chilcotin-Nechako region until at least the Santonian (Kasalka and upper Kingsvale groups, Powell Creek formation, unnamed volcanics and possibly the Brian Boni Formation). In Central Chilcotin-Nechako region volcanism was succeeded by marine sedimentation in the Santonian which continued until Maastrichtian time, indicating marine conditions persisted on the mainland of British Columbia well beyond the previously documented Albian limit. Sediments in the Nazko Basin were sourced from the Omineca Belt and the Cache Creek Terrane to the east and the Insular Terrane to the west. In the southern region detritus was also provided by the Bridge River Terrane. New data from this study indicate mid to Late Cretaceous sediments within the Chilcotin-Nechako region are zeolite facies. This low grade of metamorphism is probably due to comparatively low heat flow in the Chilcotin-Nechako region.  i i i  When compared to equivalent strata exposed to the north, sediments within the Nazko Basin have markedly lower maturation values even though they have experienced the same amount of burial. Sediments with zeolite grade metamorphism have the potential to lie within the oil window and thus may contain significant hydrocarbon reserves. However, Rock-Eval pyrolysis and TOC analyses of outcrop and well samples indicate the overall hydrocarbon potential of the Chilcotin-Nechako region is low.  iv TABLE OF CONTENTS ABSTRACT^ LIST OF TABLES^ LIST OF FIGURES^ LIST OF PLATES^ ACKNOWLEDGEMENT^  ii vi vii ix xi  INTRODUCTION^ A. LOCATION AND ACCESS^ B. PREVIOUS WORK/REGIONAL GEOLOGY^ C. PRESENT GEOLOGIC WORK ^ D. REFERENCES^  1 3 5 12 14  PART I: STRATIGRAPHY OF CRETACEOUS STRATA WITHIN THE CHILCOTINNECHAKO REGION ABSTRACT - PART I^ 17 A. INTRODUCTION^ 18 B. METHODS and RESULTS^ 19 C. STRATIGRAPHY OF NORTHERN CHILCOTIN-NECHAKO REGION ^21 Gramophone and Reiseter Creeks^ 21 Canyon Creek^ 26 Bulkley Valley and Tellcwa Area ^ 31 Houston Tommy and Denys Creeks, Morice River and Lake Areas ^37 Tahtsa, Ootsa and Francois Lakes Area^ 44 AGE, DEPOSITIONAL ENVIRONMENT AND PROVENANCE ^46 Age^ 46 Provenance^ 54 55 Depositional Environment^ D. STRATIGRAPHY OF CENTRAL CHILCOTIN-NECHAKO REGION ^59 AGE, PROVENANCE AND DEPOSITIONAL ENVIRONMENT ^67 Age^ 67 Provenance^ 84 Depositional Environment^ 84 E. STRATIGRAPHY OF SOUTHERN CHILCOTIN-NECHAKO REGION^85 Potato Mountain^ 86 West of Mount Tatlow^ 90 Taseko River^ 95 Chilko River^ 100 Churn Creek^ 103 AGE, DEPOSITIONAL ENVIRONMENT AND PROVENANCE ^117 Age^ 117 Depositional Environment and Provenance ^ 117 DISCUSSION^ 120 F. REGIONAL CORRELATIONS^ 126 G. BASIN FORMATION^ 134 BASIN INFILLING^ 136 H. SUMMARY AND CONCLUSIONS ^ 142 I. REFERENCES^ 146 PART II: THERMAL MATURATION AND SOURCE ROCK POTENTIAL OF CRETACEOUS STRATA IN THE CHILCOTIN-NECHAKO REGION  V  ABSTRACT - PART II^ 150 151 A. INTRODUCTION^ B. METHODS^ 153 1. VITRINITE REFLECTANCE^ 153 153 2. ROCK-EVAL PYROLYSIS ^ 161 C. RESULTS^ 161 1. MATURATION^ 2. SOURCE ROCK POTENTIAL^ 166 (i) NAZKO D-96-E WELL^ 170 (ii) CHILCOTIN B-22-K WELL^ 178 (iii) REDSTONE D-94-G WELL^ 186 (iv) REDSTONE B-82-C WELL^ 192 197 (v) PUNCHAW WELL^ (vi) OUTCROP SAMPLES FROM THE CHILCOTIN-NECHAKO REGION 202 221 D. DISCUSSION^ 1. MATURATION^ 221 2. SOURCE ROCK POTENTIAL ^ 226 E. SUMMARY AND CONCLUSIONS ^ 227 F. REFERENCES^ 230 APPENDIX A - LOCATION MAPS^ 232 APPENDIX B - STRATIGRAPHIC SECTIONS^ 256 APPENDIX C - THIN SECTION DESCRIPTIONS^ 331 APPENDIX D - PALYNOLOGY RESULTS^ 375 APPENDIX E - ROCK-EVAL DATA FOR OUTCROP SAMPLES^ 408 APPENDIX F - ROCK-EVAL DATA FOR THE NAZKO D-96-E, CHILCOTIN B-22-K, REDSTONE D-94-G, REDSTONE B-82-C AND PUNCHAW WELLS ^431  vi LIST OF TABLES Table 1. - Summary of rock units in the Chilcotin-Nechako Region. ^ Table 2. -Bedding thicknesses used in this study.^  8 20  Table 3.- Sandstone compositions in northern Chilcotin-Nechako Region. ^ 25 Table 4 - Palynology data for the northern Chilcotin-Nechako Region^  48  Table 5 - Palynology data for the central Chilcotin-Nechako Region. ^  68  Table 6 - Measured and calculated parameters derived from Rock-Eval pyrolysis.^155 Table 7 - Geochemical parameters describing source rock generative potential (Peters, 1986). ^156 Table 8 - Geochemical parameters describing the type of hydrocarbon generated (Peters, 1986).^156 Table 9 - Geochemical parameters describing the quality of organic matter.^ 158 Table 10 - Geochemical parameters describing the maturity of organic matter (Peters, 1986). ^160 Table 11 - Geochemical parameters describing hydrocarbon potential (Tissot and Welte, 1984). ^160 Table 12 - Vitrinite reflectance data for outcrop samples in the Chilcotin-Nechako region. ^162 Table 13 - TAI values for the Nazko D-96-E and Chilcotin B-22-K wells. ^  165  Table 14 - Summary of Rock-Eval pyrolysis results for the Nazko D-96-E well.^171 Table 15 - Summary of Rock-Eval pyrolysis results for the Chilcotin B-22-K well. ^179 Table 16 - Summary of Rock-Eval pyrolysis results for the Redstone D-94-G well. ^187 Table 17 - Summary of Rock-Eval pyrolysis results for the Redstone B-82-C well.^193 Table 18 - Summary of Rock-Eval pyrolysis results for the Punchaw well. ^  198  Table 19 Summary of Rock-Eval pyrolysis results for outcrop samples from the Chilcotin-Nechako Region.^ 203 Table 20 - Correlation of metamorphic fades with vitrinite reflectance and TAI values (Read et al., 222 1988).^  vi i  LIST OF FIGURES Figure 1. Geographic location of the Chilcotin-Nechako Region. ^  2  Figure 2. Map of the Chilcotin-Nechako Region with geographic locations frequently used in this study.  4  Figure 3 - Map of British Columbia showing superterranes I and II as defined by Monger et al. (1982).7 Figure 4 - Folk Classification system for sandstones. ^  20  Figure 5 - Composite stratigraphic section for sediments exposed in Reiseter Creek. These sediments have been mapped as part of the Kitsun Creek sediments of the Skeena Group (Tipper, 1976). 22 Figure 6 - Composite stratigraphic section for Canyon Creek.^  29  Figure 7 - Composite stratigraphic section for Skeena Group sediments (Red Rose division) exposed in Houston Tommy Creek.^ 38 Figure 8 - Sections measured through Skeena Group sediments (Red Rose division). a). Near Morice Lake, b). near Morice River and c). near Denys Creek.^ 39 Figure 9 - Stratigraphic section measured through Skeena Group sediments (Red Rose division) exposed on Swing Peak.^  45  figure 10 - Skeena Group as defined by Tipper and Richards, 1976.^  47  figure 11 - Stratigraphy of Skeena Group sediments in the Telkwa area (Palsgrove, 1990). ^53 Figure 12 - Subsurface stratigraphic sections compiled from well data. a) Nazko D-96-E well (information from Canadian Hunter and this study) and b) Chilcotin B-22-K well.^60 Figure 13 - Stratigraphic section measured through the Relay Mountain Group exposed on Potato Mountain.^  87  Figure 14 - Stratigraphic section measured through the Taylor Creek Group exposed on a ridge west of Mount Tatlow.^ 91 Figure 15 - Stratigraphic section measured through Kingsvale Group sediments exposed on the east side of Taseko River, near Davidso'/gure 16 - Stratigraphic section measured through Kingsvale Group sediments near the confluence of Vick Creek and Taseko River. This section lies below that in figure 15.^ 97 Figure 17 - Stratigraphic section measured through sediments exposed in Chilko River, just south of Highway 20 in Bull Canyon.^ 102 Figure 18 - Composite stratigraphic section for sediments exposed in Churn Creek. Information from this study and Mahoney et al., 1992. Figure from Mahoney et al., 1992.^104  viii Figure 19 - Paleocurrent data for sediments in the lower unit exposed in Churn Creek. a) Stereoplot of the poles to cross-bedding, b) stereoplot of rotated poles to cross-bedding and c) rose diagram based on the data in b^ 118 Figure 20 - Red Rose and Brian Boru Formations defined by Sutherland Brown. ^121 Figure 21 - General stratigraphy of the Battlement Ridge group. ^  124  Figure 22 - General stratigraphic section for the Kingsvale Group. ^  127  Figure 23 - Regional correlation of Cretaceous stratigraphy within the Chilkotin-Nechako Region. 128 Figure 24 - Regional correlation block diagram, based on figure 23. ^  130  Figure 25 - Nazko basin paleogeography^  138  Figure 26 - Location of wild catwells drilled in the Chilcotin-Nechako Region. (From Hickson 1990). Figure 27 - Van Krevelen diagram. ^  152 158  Figure 28 - Surface maturation map for outcrop samples in the Chilcotin-Nechako Region ^167 Figure 29 - HI versus OI plot for outcrop samples in the Chilcotin-Nechako region. ^168 Figure 30 - Surface maturation map with the oil window shown, for outcrop samples in the ChilcotinNechako Region.^ 169 Figure 31 Rock-Eval results for the Nazko D-96-E well.^  175  Figure 32 - Rock-Eval results for the Chilcotin B-22-K well ^  183  Figure 33 - Rock-Eval results for the Redstone D-94-G well ^  189  Figure 34 - Rock-Eval results for the Redstone B-82-C well^  194  Figure 35 - Rock-Eval results for the Punchaw well ^  199  Figure 36 Rock-Eval results for outcrop samples in the Chilcotin-Nechako Region ^215  ix LIST OF PLATES Plate 1- Interbedded sandstone and shale exposed in Reiseter Creek^ 23 Plate 2 - Conglomerate (upper photo) and sandstone (lower photo) from the Meed Creek area. 27 Plate 3 - Photomicrographs of the sandstone in plate 2. ^  28  Plate 4 - Sandstone exposed in Canyon Creek.^  32  Plate 5 - Photomicrographs of the sandstone in plate 4. ^  33  Plate 6 - Volcanic rock (?) interbedded with Skeena Group sediments in the Bulkley River at Smithers 35 Plate 7 - Photomicrographs of the volcanic rock in plate 6.^  36  Plate 8 - Interbedded sandstone and shale exposed in lower Houston Tommy Creek (upper photo). Chert rich sandstone exposed in upper Houston Tommy Creek (lower photo). ^40 Plate 9 - Sandstone from the Morice Lake area. ^  41  Plate 10 - Photomicrographs of the sandstone in plate 9. ^  42  Plate 11 - Thalassinoides burrows exposed in lower Houston Tommy Creek. ^58 Plate 12 - Chert pebble conglomerate (upper photo) and pebbly sandstone (lower photo) exposed in the Nazko area.^ 63 Plate 13 - Sandstone exposed in the Nazko area. ^  64  Plate 14 - Photomicrographs of the sandstone in plate 13.^  65  Plate 15 - Very coarse grained sandstone of the Relay Mountain Group exposed on Potato mountain 88 Plate 16 - Photomicrographs of the sandstone in plate 15.^  89  Plate 17 - Interbedded conglomerate, sandstone and shale (upper photo). Fossil plant material in siltstone (lower photo); Taylor Creek Group near Mount Tatlow. ^ 92 Plate 18 - Calcareous concretions (upper photo) and burrows (lower photo) in the Taylor Creek Group near Mount Tatlow.^ 94 Plate 19 - Conglomerate (upper photo) and sandstone (lower photo) of the Kingsvale Group exposed near Davidson Bridge, Taseko River.^ 98 Plate 20 - Photomicrographs of the sandstone in plate 19.^  101  Plate 21 - Chert pebble conglomerate of the lower unit of the Silverquick formation, exposed in Churn Creek.^ 106  x Plate 22 - Sandstone from the lower unit of the Silverquick formation (upper photo). Photomicrograph of the above sandstone (lower photo).^ 108 Plate 23 - Sandstone from the transition zone between the lower and middle units of the Silverquick formation exposed in Churn Creek (upper photo). Photomicrograph of sandstone in the upper unit. 110 Plate 24 - Channeled conglomerate (upper photo) and volcanic clast conglomerate of the middle unit, exposed in Churn Creek.^ 111 Plate 25 - Lahar used to correlate sections in Churn Creek (upper photo). Purple siltstone slopes with interbedded, resistant sandstone and conglomerate. ^ 113 Plate 26 - Granitic clast conglomerate of the upper unit, exposed in Churn Creek. ^116 Plate 27 - Plaeocene sediments exposed in Gosnell Creek. ^  123  Plate 28 - Vitrinite (grey) and inertinite (white) found in outcrop samples.^220  xi ACKNOWLEDGEMENTS I would like to thank R.M. Bustin for his supervision of this thesis. Many thanks are extended to C.J. Hickson of the Geological Survey of Canada and P. Desjardins of the British Columbia Ministry of Energy Mines and Petroleum Resources for logistical support and help throughout. H.W. Tipper provided much appreciated initial impetus to the project. Informative discussions with T.A. Richards and J.B. Mahoney were much appreciated. The manuscript benefited greatly from reviews by R.M. Bustin, C.J. Hickson and W. Barnes. I also thank Canadian Hunter Exploration Ltd. for sharing unpublished information and providing samples. J.B. Mahoney kindly provided field notes and photographs. Paleontological identification were carried out by H.W. Tipper (macrofossils) and G. Rouse (palynology). Thanks to Doni Jacklin and Y. Douma for assistance with laboratory work. Special thanks to my good friends D. Harrison and T. Delaney for their many hours of help. D. Harrison is also thanked for excellent field assistance and drafting. Fellow graduate students at UBC provided moral support and valuable discussions. This project forms part of the Chilcotin-Nechako Frontier Geoscience Project and funding was provided by the Geological Survey of Canada and EMR and NSERC grants to R.M. Bustin, plus an NSERC graduate fellowship and GREAT awards.  1  INTRODUCTION  Cretaceous sediments of the Skeena and Kingsvale Groups and the informally defined Battlement Ridge group are exposed within the ChilcotinNechako region of British Columbia (Fig. 1). These Albian to Cenomanian rocks provide information on the tectonic evolution of the southern Canadian Cordillera and record the transition from a dominantly sedimentary to a volcanic province in the Cenomanian. The strata further document changes in aerial extent of a Cretaceous sea that, at one time, covered the entire Chilcotin-Nechako region, and demonstrate that marine conditions for central British Columbia, previously thought to have ended in the Albian (Tipper, 1984), persisted until CampanianMaastrichtian time. An examination of the metamorphic map of the Canadian Cordillera (Read 1988) shows that Cretaceous sediments within the Chilcotin-Nechako region were mapped within the subgreenschist facies of metamorphism. New data, from this study, suggest that Mid to Late Cretaceous sediments are dominantly zeolite grade. This has important implications for the hydrocarbon potential of the ChilcotinNechako region because sediments with zeolite grade metamorphism could potentially lie within the oil window, and thus have significant hydrocarbon potential. Nine exploratory wells were drilled in the Nazko-Redstone area between 1960 and 1986, but the remainder of the region is unexplored. Rocks within the Chilcotin-Nechako region have been little studied due to limited outcrop and accessibility. This lack of available geologic data has severely hindered exploration for minerals and hydrocarbons, as well as attempts to interpret the regional geology and correlate rocks between map sheets within the ChilcotinNechako region.  CHILCOTIN  ^  2  NECHAKO REGION  • SMITHERS  SMITHERS 93L FORT FRASER 93K NECHAKO WHITE SAIL^ RIVER 93F LAKE^ 93E  PRINCE GEORGE 93G  MOUNT WADDINGTON 92N  40 20 0 50 30 10  •  LILOOET  Figure 1. Geographic location of the Chilcotin-Nechako Region. Also shown are NTS map sheet names and numbers.  3  The objectives of this study are: 1) to establish the Cretaceous stratigraphy and the sedimentary and tectonic evolution of the region; 2) to produce a metamorphic map of the Chilcotin-Nechako region delineating areas within the oil window; and 3) to define the hydrocarbon source potential of the region. This study is divided into two parts: part I covers stratigraphy and the sedimentary and tectonic evolution of the Chilcotin-Nechako region, and part II defines and interprets the maturation and source rock potential. In part I the aforementioned Cretaceous sediments are described, a general regional stratigraphy is defined and a paleogeographic model for the formation of the basin of deposition (the Nazko Basin) is proposed. In part II the hydrocarbon source potential and maturation of Cretaceous sediments within the study area are examined, and the thermal metamorphism of sediments within the ChilcotinNechako region is compared to that of correlative sediments in the Intermontane Belt. This study is a first attempt to tie together Cretaceous sediments within the Chilcotin-Nechako region and must be considered preliminary as it is based on limited outcrop exposure spread over a vast area. Although covered by regional reconnaissance mapping, only scattered detailed studies have been carried out in the Chilcotin-Nechako region (Garver, 1989; Palsgrove, 1990) and large gaps remain to hinder syntheses of regional relationships. Cordilleran evolutionary ideas are filled with speculation and rapidly evolving interpretations and it is in this vein that this thesis is presented. A. LOCATION AND ACCESS  The Chilcotin-Nechako region lies in south-central British Columbia, and covers an area of about 100,000 km 2 stretching from 51°N latitude near the town of Lillooet, north to 55°N latitude close to the town of Smithers (Figs. 1 and 2). The  CHILCOTIN - NECHAKO REGION  Figure 2. Map of the Chilcotin-Nechako Region with geographic locations frequently used in this study. Locations not shown in this figure can be found in Appendix A.  4  5  eastern limit of the study area is the Fraser Fault; the Coast Mountains form the western boundary. Geographic regions frequently referred to in this paper are shown in figure 2 or Appendix A. The Tyaughton Basin area refers to the southernmost part of the Chilcotin-Nechako region, south of the Yalakom Fault (Fig. 2). The topography of the Chilcotin-Nechako region is subdued and, consequently, Cretaceous sediments are poorly exposed; most exposures are in creeks or roadcuts. The exception are Cretaceous sediments in the Tyaughton Basin area, where excellent exposures occur along ridge tops. A road network is maintained, within the Chilcotin-Nechako region, by logging or mining companies, portions however, are restricted to four wheel drive vehicles. Areas without roads can be reached by helicopter, boat or on foot. Logistical support for fieldwork is available in the larger towns such as Smithers, Williams Lake and Quesnel. In the southernmost region helicopter support is available at Bluff Lake, Lillooet and Goldbridge. B. PREVIOUS WORK/REGIONAL GEOLOGY  General regional mapping by field parties from the Geological Survey of Canada (including: Tipper, 1955, 59, 61, 63, 69, 76, 78; Duffel, 1959; Woodsworth, 1978; Hickson et al., 1991) and the British Columbia Geological Survey (including: Schiarizza et al., 1989; Garver et al., 1989; Maclntyre et al., 1989 and McLaren, 1990) constitutes most previous work in the Chilcotin-Nechako region. There have been no prior attempts to correlate sediments within the Chilcotin-Nechako region, although Duffel (1959) and Jeletzky and Tipper (1968) did point out similarities between Cretaceous sediments in Taseko Lakes (920) and Whitesail Lake (93E) map areas. Several detailed studies of Cretaceous sediments have been carried out including: Garver's (1989) study of the Taylor Creek and Battlement Ridge groups  6  in the eastern Tyaughton Basin and Palsgrove's (1990) study of Skeena Group sediments in the Telkwa area. There is, however, a distinct paucity of detailed stratigraphic and sedimentologic data for most of the region. The Chilcotin-Nechako Region lies within the Intermontane Belt of British Columbia (Fig. 1) on Terrane I of Monger  et a/. (1982; Fig 3) and includes rocks  ranging in age from Paleozoic to Recent. Table 1 is a summary of rock units within the Chilcotin-Nechako Region. A complete description of all units exposed in the Chilcotin-Nechako region is beyond the scope of this paper; the following discussion summarizes the main units. Paleozoic rocks within the Chilcotin-Nechako Region include those of the Central Gneiss Complex, the Cache Creek, Slide Mountain, Gamsby and Cariboo Groups%-med units (Table 1). The Cache Creek Group is of particular interest to this study as it is believed to be a source of chert detritus in later sedimentary rocks. Lithologies within the Cache Creek Group include chert, argillite, shale, greywacke, mafic volcanics and minor limestone lenses (Tipper, 1978). Permian to mid Jurassic (Cordey  et al.,  1987) rocks of the Cache Creek  Group are part of the Cache Creek Terrane, interpreted to be a subduction complex related to arc activity in the tectonic terranes Quesnellia and Stikinia (Monger, 1977). The Cache Creek Terrane was thrust over Stikinia when the amalgamation of terranes, known as Terrane I (Monger,  et al.,  1982), finally welded to the North  American Continent. Mesozoic rocks exposed within the northern and north central parts of the Chilcotin-Nechako Region include the Takla, Hazelton, Bowser Lake and Skeena Groups. The Upper Triassic Takla Group comprises basaltic and andesitic volcanic rocks, pelitic sedimentary rocks and minor carbonate (Tipper and Richards, 1976) resulting from widespread, primarily submarine island arc volcanism (Monger,  7  Figure 3 - Map of British Columbia showing superterranes I and II as defined by Monger et al. (1982).  8  Table 1. Summary of rock units in the Chilcotin-Nechako Region, information from  published 1: 250,000 map sheets.  ^ ^  SMITHERS 93L VHITESAIL 93E NECHAK^ 93F Tipper, (1976) Voodsworth, (1980) Tipper, (1963) Poplar Butte Volcanics  >- PLIOCENE CY Q MIOCENE I—  fY Li]  I--  0  OLIGOCENE EOCENE  ^  a a —  PALEOCENE MAASTRICT.  o  tr i.3  2 2 --a—  Is 2  Li 13  '  CAMPANIAN SANTONIAN (/)  CONIACIAN  D o TURONIAN  V V  8  x-7  V^...  -1-; 40'^a^o ,^-t3^ce cs  L in ^in J -pce u , E c % , g a) o  o_  io 0u CENOMANIAN 431 1,E -13 i.nw ' Q H. ALBIAN  ce L'  W APTIAN CL  t  D L  PO PO c  BARREMIAN  0  t_  HAUTERIVIAN  0  Ootsa Lake Group  L3  d  c 0.0 a,  D TOARCIAN ---) PLIENSBACH. SINEMURIAN  10:1  v  cu  v. 41b.^A  0^0 L._^ LL  p" -v •  CL In cu 3 3 _Y 0 0 d L PO _I  v'  V  -t-> 0 ci  11, CI  Y  4- 4->  4- -1-'  4° +'  (_  +' (5 in I-"CU  d .-' U1 L. 0 E  w  vi CI a,  +'  _c  3  c 2 o 7-- 4-> '^IA  L  o z  10 13  a a,  c _y -I-) w L  a o  I o^i  t  a)  -.3 c 3 o x >,  .  I  C  o 4-> a -a.,"^3  0  d 0 0 L  o 4->  TD N d  s_  L-  __Y  I--  1  • 10.4■ ■ al■ A.. /h. A..  Cache Creek I-- SCYTHIAN ^-Eco Group PERMIAN 4 Cache Creek if ^73 4 Group PENNSYLV. 4 Mountain 1 i cl 41 u MISSISSIPI. Quartzite, urouo A -6 .. 3 4 c vi shale, c x DEVONIAN o c2-d^IA tinestone & 1 a, 4> E u tri netanorphics +0, -E^z 7ci 7'1 SILURIAN Cariboo in cs^a E a, cy U^L L o Group c.z^2 +"c(__) ORDOVICIAN >^0 ci,^1 u CAMBRIAN i I^+°'  ■•■  L W  1:5  it2  c  0_ D  d Tyu CC  •  c  a 3 o  Hazelton Group  d  ,  ›, 0  u  I o  Sediments & Limestone  o Cs.  d S_  d --)^I--  -6 ^171, N 0^N 0 L^0  „ „  Pv  1_  o_ v C o  til u  c^c 0^o 4-> a^4-,  V V V  Z >--  d o _Y  c 0 4-> a 7:6 3  c?' V V  V) >-  Kingsvate Gp.  c i a  o^o L. s_  0  N 0 0  -P CI  o .775'  Jackass Mtn Group 06  lir  d  3  VV VV  c..:)  -8 a  tfi X U  Ul^Cu -i->^c W 0 W -P E U1  LY  w E  o  3 3 75 0 L 0 0  co  •^  mir  v) f,  u^,„,  -  _C c  a o s... -P o in  41  E W 0 E -t-, =i-  u -1-> -C c  d^(1) U E  - c o 0, > v) -  Cache Creek Group  0  a, E  ^0, E  ^E 0  1-j -Ts +9^t cu cu CA  V)  7 V V V V  VV  7 v v v v v v C 7 VVV vvv,  7vvv V V V  7^V  T ^ b ridge  u 06 U^06 Ln ,^:f^u) :f Group 01.1p la in a^4, a_ u±' L^c  cu m cz  vi^(r)  f  ,  °' _c  -4-'  Skeena Group  Gambier Group  o -3'  _c X S  _c -I-,  -I-' 3 c0 ,)  cn 0 -C I-3  o -5-  0  3  >a in 3  8 r1 ,V  _c s_  C.1 0  d^d Tz's^- --s >>-  in  —  W  Takla Group  o  _I a 3 d 0 ln L 0  - I  a ci. eA. A 1,  E^E  v  •  Bowser Lake Grou p  L  8 ^ U 0  -4-,^A-,  AA.  L E a _.I  NOR IAN v) LADINIAN Q ANISIAN  A.  V V  HETTANGIAN s-i KARNIAN  ... ... AI  d y 0  (/)  < AALENIAN  77 77  in o  _Y 0  KIMMERIDGE.  i--, BATHONIAN v) BAJOCIAN  v v  7 V •  c 4-7 o a -",-- u L  -5  s_ 0  TITH^NIAN  (__)  V V  7 v V------ v v  4  -8  BERRIASIAN  CALL^VIAN  4  V  X 0_  VALANGINIAN  OXFORDIAN  V  V V  IP  • ■•  MT WADDINGTON 92N TASEKO LAKES 920 RoddickLTipper (1985) Tipper, (1978) v  3  -  L_I  U  ° vv  7  '1/47^v Y^Cu a' Di  0 cs 111 W -1--' X 0 d 0 _J  LA 0  in^0) -P 0 cs  7 V  IV^  a 03  P v v v - - -  '7 V  Endako Endako Group Grou• 1  0 -Y  d 3  0 _j  Tipper, (1961)  ChIlco-tin /Group  RECENT  QUESNEL 93B Tipper, (1969) Tipper, (1959)  PRINCE GEORGE 93G ANAHIM LAKE 93C  06  • -.11'  0 c -1-,^0,) ui E a) -75 Ew V)  .  4  4  10  1977). The most areally extensive rocks within the Chilcotin-Nechako Region are those of the Lower to Middle Jurassic Hazelton Group (Leech, 1909; Hanson, 1925; Armstrong, 1944; Tipper, 1955, 1971; Tipper and Richards, 1976). The Hazelton Group consists mainly of arc-related, folded andesitic volcanic and sedimentary rocks. Unconformably overlying the Hazelton Group are successor basin deposits of the mid to Upper Jurassic Bowser Lake and Lower to mid Cretaceous Skeena Groups (Tipper and Richards, 1976). The Bajocian to Kimmeridgian Bowser Lake Group comprises a thick assemblage of marine and nonmarine sediments composed predominantly of shale, siltstone, sandstone and conglomerate with lesser volcanics (Tipper and Richards, 1976). The Skeena Group, as defined by Tipper and Richards (1976), consists of basal Hauterivian to (?) Albian Kitsun Creek Sediments comprising conglomerate, greywacke, shale, coal, minor tuff and breccia; overlying Hauterivian (?) to Albian (?) Rocky Ridge Volcanics made up of augite porphyry flows and breccias, hornblende andesite and basic flows; middle Albian unnamed sediments including micaceous greywacke, shale, minor conglomerate and coal; middle Albian Red Rose Formation comprising shale, chert pebble conglomerate and minor micaceous greywacke; unnamed Albian and/or younger andesitic and dacitic breccias ; and uppermost Albian and/or younger porphyritic tuff, breccia and flows known as the Brian Boru Formation. In Whitesail map area (93E) Maclntyre (1985) defined volcanic rocks overlying sediments of the Skeena Group as the Kasalka Group. Mesozoic rocks exposed in the southern Chilcotin-Nechako region include the Relay Mountain, Taylor Creek, Jackass Mountain and Battlement Ridge Groups. The Upper Jurassic (Oxfordian) to Lower Cretaceous (Barremian) sedimentary rocks of the Relay Mountain Group were deposited southwest of the Yalakom Fault on the northeast side of the Tyaughton Basin (Tipper, 1969b).  11  These sediments are made up of greywacke, conglomerate, arkose, shale and siltstone with abundant Buchia, Inocerami and belemnite fossils (Tipper, 1969b). Upper Jurassic - Lower Cretaceous rocks on the southwest side of the Tyaughton Basin are contemporaneous with part of the Relay Mountain Group, but to the southwest the section is dominantly volcanic (Tipper, 1969b). The lower Albian (or older) to middle - upper Albian Taylor Creek Group comprises marine sedimentary rocks deposited in the centre or on the southwest side of Tyaughton Basin (Tipper, 1969b). These sediments include chert pebble conglomerate, shale, siltstone, sandstone and some volcanics (Tipper, 1969b). The Jackass Mountain Group is a non-marine sequence of greywacke, siltstone and conglomerate that was deposited along the northeastern part of Tyaughton Basin in Aptian and Albian time (Tipper, 1969b). This group is believed to be correlative as a whole or in part with the Taylor Creek Group with which it interfingers (Tipper, 1969b). The Taylor Creek Group is overlain by the Battlement Ridge Group (Glover et al., 1988), which comprises nonmarine sedimentary, volcaniclastic and volcanic  rocks of latest Albian (?) to Late Cenomanian age previously assigned to the Kingsvale Group by Jeletzky and Tipper (1968). The informally named Battlement Ridge Group (Glover  et al.,  1988) is subdivided into the basal clastic Silverquick  formation (informal) which grades up into an overlying volcanic unit known as the Powell Creek formation (informal; Glover  et al.,  1988). The Silverquick formation  comprises two informal members: the lower member is composed of dominantly chert pebble to cobble conglomerates with minor sandstone interbeds. The lower member is gradationally overlain by an upper member of volcanic cobble to boulder conglomerate. The Powell Creek formation comprises dominantly andesitic to basaltic volcanic breccia and lapilli tuff, intercalated with fine grained tuff, basaltic to andesitic flows and epiclastic sediments. This formation can locally be divided  12  into a lower massive unit and an upper bedded unit dominated by lahars and epiclastic sediments (Glover et al., 1988). The Spences Bridge Group, exposed in the eastern part of the southern Chilcotin-Nechako region, comprises a sequence of Late to latest Albian, intercalated andesitic to rhyolitic lavas and clastic rocks (Thorkelson, 1985; Thorkelson and Rouse, 1989). This group is, in part, time equivalent to the Late Albian to Cenomanian Battlement Ridge Group and may have been the source of volcanic detritus for the upper member of the Silverquick formation (Mahoney et al., 1992). Mesozoic strata within the Chilcotin-Nechako Region are unconformably overlain by Eocene volcanics and sediments (Endako and Ootsa Lake Groups) and by Pliocene and Miocene plateau basalts (Chilcotin Group; Tipper and Richards, 1976; Tipper, 1959, 63, 69, 78; Mathews, 1989; Rouse et al., 1990; Hickson et al., 1991).  C. PRESENT GEOLOGIC WORK  This study is part of a Geological Survey of Canada's Frontier Geoscience Project charged with studying the hydrocarbon potential of the Chilcotin-Nechako region. The present study was undertaken to to answer basic questions concerning stratigraphy, source rock potential and thermal history of Cretaceous strata within the Chilcotin-Nechako region. Preliminary results of this work were published in 1990 and 1991 (Hunt and Bustin, 1990; Hickson, 1990; Hickson et al., 1991). Fieldwork for this study was conducted during the summers of 1989 and 1990 when as many accessible outcrops of Cretaceous rocks as possible were examined. Field work involved sample collection and the measurement of stratigraphic sections. Samples of well cuttings were collected from the Chilcotin B-22-K and Nazko D-96-E wells (Fig. 2).  13  Laboratory work on samples collected in the field included thin section petrographic studies, palynological dating, Rock-Eval pyrolysis analyses and vitrinite reflectance studies. Field data are used for correlation of fades between measured stratigraphic sections.  14  D. REFERENCES Armstrong, J.E., 1944. Preliminary map Smithers British Columbia. Geological Survey of Canada Paper 44-23. Cordey, F., Mortimer, N., DeWever, P. and Monger, J.W.H., 1987. Significance of Jurassic radiolarians from the Cache Creek terrane, British Columbia. Geology, vol. 15, p. 1151-1154. Garver, J.I., 1989. Basin evolution and source terranes of Albian-Cenomanian rocks in the Tyaughton Basin, southern British Columbia: implications for mid-Cretaceous tectonics in the Canadian Cordillera. PhD thesis, University of Washington, 227 p. Garver, J.I., Schiarizza, P. and Gaba, R.G., 1989. Stratigraphy and structure of the Eldorado Mountain area, Chilcotin Ranges, southwestern British Columbia. British Columbia ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1988. Paper 1989-1, p. 131-143. Glover, J.K., Schiarizza, P and Garver, J.I., 1988. Geology of the Noaxe Creek map area (920/02). British Columbia Ministry of Energy Mines and Petroleum Resources Geological Fieldwork, 1987. Paper 1988-1, p. 105-123. Hanson, G., 1925. Driftwood Creek map area, Babine Mountains, British Columbia. Geological Survey of Canada Summary Report 1924, part A, p 19-37. Hickson, CJ., 1990. A new Frontier Geoscience Project: Chilcotin-Nechako region, central British Columbia. Current Research, Part F, Geological Survey of Canada, Paper 90-1F, p. 115-120. Hickson, C.J., Read, P., Mathews, W., Hunt, JA., Johansen, G. and Rouse, G., 1991. Revised geological mapping of northeastern Taseko Lakes map area, British Columbia. Current Research, Part A, Geological Survey of Canada, Paper 91-IA, p. 207-217. Hunt, JA. and Bustin, R.M., 1990. Stratigraphy, organic maturation and source rock potential of Cretaceous strata in the Chilcotin-Nechako region (Nazko Basin) Current Research, Part F, Geological Survey of Canada, Paper 90-1F, p. 121-127. Jeletzky, JA. and Tipper, H.W., 1968. Upper Jurassic and Cretaceous rocks of Taseko Lakes map area and their bearing in the geological history of southwestern British Columbia. Geological Survey of Canada Paper 67-54, 218 p. Leech, W.W., 1910. The Skeena River district. Geological Survey of Canada, Summary Report 1909, Sessional Paper # 26, p. 61-68. Maclntyre, D.G., 1985. Geology and mineral deposits of the Tahtsa Lake district, west-central British Columbia. Ministry of Energy, Mines and Petroleum Resources Bulletin 75, 82 p. Maclntyre, D.G., Desjardins, P. and Koo, J., 1989. Geology of the Telkwa River area (NTS 93L/11). British Columbia Ministry of Energy, Mines and Petroleum Resources, Open File 1989-16, . Mahoney, .J.B., Hickson, C.J., van der Heyden, P. and Hunt, JA., (in press, 1992). Stratigraphy of the Late Albian-Early Cenomanian Silverquick Conglomerate, Gang Ranch area: evidence for active basin tectonism. Geological Survey of Canada Paper. Mathews, W.H., 1989. Neogene basalts in south-central British Columbia: geology, ages, and geomorphic history. Canadian Journal of Earth Sciences, vol. 26, p. 969-982.  15 McLaren, G.P., 1990. A mineral resource assessment of the Chilko Lake planning area. British Columbia ministry of Energy, Mines and Petroleum Resources, Bulletin 81, 117 p. Monger, J.W.H., 1977. The Triassic Takla Group in McDonnel Creek map area, north central British Columbia. Geological Survey of Canada Paper 76-29. Monger, J.W.H., Price, RA. and Tempelman-Kluit, D.J., 1982. Tectonic accretion and the origin of the two major metamorphic and plutonic welts in the Canadian Cordillera. Geology, V. 10, p. 70-75. Palsgrove, R.J., 1990. Stratigraphy, sedimentology and coal quality of the lower Skeena Group, Telkwa Coalfield, central British Columbia (93L/11). M.Sc. thesis, University of British Columbia, Vancouver, 130 p. Roddick, JA. and Tipper, H.W., 1985. Mount Waddington, 92N. Geological Survey of Canada Open File 1163. Rouse, G.E., Mathews, W.H. and Lesack, KA., 1990. A palynological and geochronical investigation of Mesozoic and Cenozoic rocks in the Chilcotin-Nechako region of central British Columbia. Current Research, Part F, Geological Survey of Canada, Paper 90-1F, p 129-133. Schiarizza, P., Gaba, R.G., Glover, J.K. and Garver, J.I., 1989. Geology and mineral occurrences of the Tyaughton Creek area (920/2, 92J/15, 16). British Columbia ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork, 1988, Paper 1989-1, p 115-130. Thorkelson, D.J., 1985. Geology of the mid Cretaceous volcanic units near Kingsvale, southwestern British Columbia. In Current Research, Part B, Geological Survey of Canada Paper 85-1B, p 333-339. Thorkelson, D.J. and Rouse, G.E., 1989. Revised stratigrphic nomenclature and age determinations for mid-Cretaceous volcanic rocks in southwestern British Columbia. Canadian Journal of Earth Sciences, vol. 26, # 10, p 2016-2031. Tipper, H.W., 1955. Nechako River, British Columbia. Geological Survey of Canada Preliminary map, Paper 54-11. Tipper, H.W., 1959. Quesnel (93B), British Columbia. Geological Survey of Canada Map 12-1959. Tipper, H.W., 1961. Prince George (93G), British Columbia. Geological Survey of Canada Map 491960. Tipper, H.W., 1963. Nechako River map area, British Columbia. Geological Survey of Canada Memoir 324, 59 p. Tipper, H.W., 1969a. Anahim Lake (93C), British Columbia. Geological Survey of Canada Map 1202A. Tipper, H.W., 1969b. Mesozoic and Cenozoic geology of the northeast part of Mount Waddington map area (92N), Coast District, British Columbia. Geological Survey of Canada Paper 68-33, 103 p. Tipper, H.W., 1971. Smithers map area, British Columbia. Geological Survey of Canada Report of Activities, Paper 71-1 part A, p 34-37. Tipper, H.W., 1976. Smithers, British Columbia, mapsheet 93L. Geological Survey of Canada, Open File 351.  16 Tipper, H.W., 1978. Taseko Lakes (920) map area. Geological Survey of Canada Open File 534. Tipper, H.W., 1984. The allochthonous Jurassic-Lower Cretaceous terranes of the Canadian Cordillera and their relations to correlative strata of the North American Craton. In: JurassicCretaceous Biochronology and paleogeography of North America, G.E.G. Westermann (Ed.), Geological Association of Canada, Special Paper 27, p 113-120. Tipper, H.W. and Richards, TA., 1976. Jurassic stratigraphy and history of north-central British Columbia. Geological Survey of Canada Bulletin 270, 73 p. Woodsworth, G.J., 1980. Geology of Whitesail Lake (93E) map area, British Columbia. Geological Survey of Canada Open File 708.  17  ABSTRACT - PART I  The Chilcotin-Nechako region lies within the Intermontane Belt of British Columbia on the western edge of Stikinia and includes the Tyaughton Basin. Exposed within the region are Early Albian to Cenomanian sediments of the Skeena, Taylor Creek, Jackass Mountain and Battlement Ridge groups plus unnamed sediments of similar age and lithology. These sediments are correlatable throughout the Chilcotin-Nechako region and were deposited in one large, initially marine, basin (Nazko Basin). They are separated from older sediments by a major hiatus. Marine conditions persisted in the northern Chilcotin-Nechako region until at least Cenomanian time, and until the Maastrichtian in the central ChilcotinNechako region. In southern Chilcotin-Nechako region, marine conditions ceased in mid Albian time with the deposition of the Silverquick formation. Latest Albian Cenomanian time marks the transition from a dominantly sedimentary to volcanic province. Volcanism was widespread throughout the Chilcotin-Nechako region until at least the Santonian (Kasalka and upper Kingsvale groups, Powell Creek formation, unnamed volcanics and possibly the Brian Boni Formation). In Central Chilcotin-Nechako region volcanism was succeeded by marine sedimentation in the Santonian which continued until Maastrichtian time, indicating marine conditions persisted on the mainland of British Columbia well beyond the previously documented Albian limit Sediments in the Nazko Basin were sourced from the Omineca Belt and the Cache Creek Terrane to the east and the Insular Terrane to the west. In the southern region detritus was also provided by the Bridge River Terrane.  18  PART I: STRATIGRAPHY OF CRETACEOUS STRATA WITHIN THE CHILCOTIN-NECHAKO REGION  A. INTRODUCTION  Cretaceous sediments exposed in the Chilcotin-Nechako region document the tectonic history of central and southern British Columbia. In particular they provide information on the timing of amalgamation of Terranes I and II, and the transition from a dominantly sedimentary to a volcanic province in latest Albian Cenomanian time. Also documented is the depositional history of Campanian to Maastrichtian marine sediments, not previously known from mainland British Columbia. However, Cretaceous stratigraphy within the Chilcotin-Nechako Region is poorly defined, exposure is limited and ages are not well constrained making any attempt at interpretation and correlation of units between different areas difficult. The purpose of this part of the study is to define and establish correlations between Cretaceous sediments throughout the Chilcotin-Nechako Region and to interpret the sedimentologic and tectonic history of the area. Measured stratigraphic sections, petrographic analyses and palynological dating techniques are used to identify and assess possible correlations. In the northern Chilcotin-Nechako Region, Cretaceous sediments are known as the Skeena Group (Leech, 1910, 1911; Armstrong 1944; Sutherland Brown, 1960; Tipper and Richards, 1976) whereas Cretaceous sediments in the southern Chilcotin-Nechako region are known as the Relay Mountain, Jackass Mountain, Taylor Creek and Kingsvale Groups (Tipper 1963 and 1978; Jeletzky and Tipper, 1968; Roddick and Tipper, 1985). Recent work, by Glover et al. (1988), in the southern Chilcotin-Nechako Region has informally defined the Battlement Ridge group comprising middle to Upper Cretaceous rocks previously assigned to the  19  Kingsvale Group (Rice, 1947; Jeletzky and Tipper, 1968). Cretaceous sediments in the central Chilcotin-Nechako Region are unnamed but have similar lithologies and ages to those to the north and south. B. METHODS and RESULTS  Where possible, stratigraphic sections were measured to provide sedimentologic and stratigraphic information and enable correlations with other areas (Appendix B). Three hundred samples of well cuttings, collected from the Nazko D-96-E and Chilcotin B-22-K wells (Fig 2), were described microscopically in order to produce a sub-surface stratigraphic column. Seven hundred and sixty outcrop samples were collected for lithologic analyses, and sixty key thin-sections analyzed (Appendix C). Six samples were collected for macrofossil and 24 for palynological dating (Appendix D); well cuttings were also dated using palynological techniques. Bedding thicknesses within stratigraphic sections were described using the scheme shown in table 2. Sandstones are named using Folk's classification scheme shown in figure 4 (Folk, 1974). Palynology is the study of palynomorphs which are useful for age dating and can be sensitive indicators of the depositional environment and the source of sediments (Traverse, 1988). Some palynomorphs, such as dinoflagellates, are marine organisms. Other palynomorphs (spores/pollen) originate almost exclusively on the continents (Traverse, 1988). Therefore, a sedimentary rock that contains dominantly dinoflagellates and no or very few spores/pollen is indicative of a marine environment of deposition whereas a rock whose palynomorph assemblage is dominated by spores and pollen is suggestive of a continental origin. Within the Chilcotin-Nechako region, the best exposures of mid to Late Cretaceous sediments occur in the northern and southern parts of the region. The central area has very subdued topography and outcrops are scarce. Information  ^ ^  20  SCALE OF STRATIFICATION THICKNESS ^ > 120 cm Very Thick ^ Thick 60-120 cm ^ Thin 5-60 cm ^ Very Thin 1-5 cm ^ Thickly Laminated 0.3-1 cm ^ Thinly Laminated < 0.3 cm  Table 2: Scale of thicknesses used to describe bedding  Q Quartzarenite Ss Sh Sandstonearenite Shalearenite Chertarenite Cht  CRF SRF  3:1  1:1  ^  1:3  RF Sedarenite  F/R ratio  VRF  l  A  Phyllarenite  Volcanicarenite  Folk classification system (1966) Figure 4: Folk classification scheme for naming sedimentary rocks Taken from Folk (1974)  MRF  21  about this part of the Chilcotin-Nechako region comes mainly from samples of well cuttings and geophysical logs for the Nazko D-96-E and Chilcotin B-22-K wells. Because of the outcrop distribution and the different terminology used in the three areas Part I has been divided into three sections which describe the stratigraphy of sediments exposed within the north, central and southern Chilcotin-Nechako region respectively. C. STRATIGRAPHY OF NORTHERN CHILCOTIN NECHAKO REGION -  Hauterivian (?) to Cenomanian fluvial and marine sedimentary rocks in the northern Chilcotin-Nechako region are up to 1000 m thick and include chert pebble conglomerate, sandstone, shale, siltstone, mudstone and coal. Following are descriptions of areas where these sediments, known as the Skeena Group, are exposed. Locations of these areas can be found in figure 2 or appendix A. Gramophone and Reiseter Creeks  Northeast of Smithers sedimentary rocks in Gramophone and Reiseter Creeks (Fig. 5) have similar lithologies comprising interbedded sandstone, siltstone and shale a total of at least 70 m thick (exposed; Plate 1; Sections 1 to 4 in Appendix B). Sediments in Reiseter Creek show no overall fining or coarsening trend. In  Gramophone Creek the amount of shale increases upsection suggesting an overall fining upward trend in that area. Very coarse grained to medium grained sandstone is dark grey to black and weathers rusty to brown-grey; in some places there is a limey coating on the weathered surface. This sandstone is fairly well sorted and composed mainly of chert and quartz with minor muscovite (1%) and very minor pyrite although the sandstone often smells sulphurous. Sandstone is very thin to very thick bedded with beds ranging from 0.15 to 10.5 m thick; some beds are planar laminated with laminations 3 to 5 mm wide. Locally very coarse grained to medium grained  22  REISETER CREEK Meters  Very coarse grained sandstone  _ 70 (...>^Li  _ 60  ) 0  0  0 ,O H r■ O 0  >  0  1111■MII!  _ 50 _ 40 _ 30 _ 20  _ 10  Coarse grained sandstone Medium grained sandstone Fine grained sandstone Shale Interbedded shale and sandstone Interbedded siltstone and sandstone Covered, probably shale  0  Figure 5 - Composite stratigraphic section for sediments exposed in Reiseter Creek. These sediments have been mapped as part of the Kitsun Creek sediments of the Skeena Group (Tipper, 1976).  23  Plate 1 - Interbedded sandstone and siltstone exposed in Reiseter Creek.  24  sandstone fills channels (2 m thick x 4 m wide) that were cut through the underlying finer grained sediments. These channels usually have small, angular pebbles (5 mm in diameter) at the base and fine upwards from very coarse grained to medium grained sandstone and rarely show any cross-bedding. Fine grained sandstone in Reiseter and Gramophone Creeks is pale to dark grey or black and often weathers rusty brown with calcite on fracture surfaces. This sandstone is usually micaceous (muscovite and/or biotite) and sometimes fissile. Fine grained sandstone beds are usually interbedded with shale or siltstone and vary in thickness from 3 to 5 m. Occasionally, repeating, coarsening upward layers, 15 cm thick, occ%- grained sandstone beds. Rarely dark grey, bright rusty orange weathering concretions 3 cm in diameter occur. Sandstone (samples J89-249 and J89-249-01 in Appendix C, Table 3) from this area is moderate to poorly sorted volcanic or chert arenite with sub-angular to sub-rounded clasts. Volcanic-arenites are composed primarily of volcanic rock fragments (68%), chert (15%) and sedimentary rock fragments (10%) with lesser quartz (2%) and plagioclase (5%) cemented by authigenic quartz. Chert-arenites are made up of quartz (45%), chert (35%) and metamorphic rock fragments (10%) with lesser sedimentary rock fragments (5%) and plagioclase (5%) in a silt to clay matrix. Siltstone in the Gramophone-Reiseter Creeks area is medium grey, sometimes carbonaceous (pieces of organic matter < 1 mm diameter), and weathers rusty red. This unit is very soft, fissile and micaceous with rare mudcracks and trace fossils (possibly grazing trails) occuring along bedding planes. Siltstone is usually very thin to thin and rarely very thick bedded, varying from 0.08 to 2 m thick. Rare pebbles, up to 2 cm in diameter, occur within this unit. Shale is pale grey brown to medium grey to dark grey with black spots, or black, and weathers rusty red. This unit is fissile, friable and sometimes micaceous.  25  Composition Sample Number  o co co  Di o) .0 E  - 8co  0  Q  t)  7%  rare  40%  'I'  0  (73 t,Lc  -2^• -c 0  B. Fri)  co cc  00 ct. LL  A s...) 0  2%  7D-  cc  Z cc  20%  7%  59%  3%  20%  30%  4%  25%  rare  45%  20%  2%  5%  15%  68%  45%  5%  35%  Kitseguecla Rd.  12%  5%  10%  J90-043-01 Kiseguecla Rd.  50%  2%  5%  J89-001-01 Hudson Bay Mountain J89-014-02 Canyon Creek J89-004-01 Driftwood Creek Rd. J89-249 Gramophone Creek J89-249-01 Gramophone Creek J90-041-01a  J89-282-08 Houston-Tommy Creek  a 0 0  co o  t) ca  .-Z  0  rare  X  X  3%  X  10%  < 1%  X  10%  2%  10%  5%  48%  8%  10%  10%  33%  47A  13%  g^c'es  g ''.: Vt.t., 11 2(0 -0  4.) 0 . RI tc, 0 0  ,,i nil)  43  < 1%  3%  5%  < 1% < 1%  35%  < 1%  38%  8%  40%  5%  2%  J89-070-01 Morice River  35%  5%  50%  5%  4%  1%  J89-067-01 Bill Nye Lake Rd.  30%  10%  15%  30%  < 1%  5%  10%  X  J89-019-01 McBride Lake  40%  10%  30%  15%  4%  1%  < 1%  X  10%  1%  50%  14%  15%  5%  2%  63%  FT#5 Bowser Lake Group  10%  15%  5%  45%  FT#18A Red Rose division  30%  6%  10%  5%  FT#4 Kitsun Creek Sediments  7%  5%  X  X 5%  X X  25% 41%  X  X  15% 5%  X  < 1%  J89-065-01 Morice Lake  J89-077-03 McDonald Landing  X  8%  X  Table 3 Sandstone compositions in northern Chilcotin-Nechako Region. X =  present  -  26  Rare, small (6 nun diameter), soft, round, black blebs (organic matter?) are found within the shale. This shale unit is very thin to very thick bedded and varies from 1.5 to 4.5 m in thickness. Where interbedded with fine grained sandstone individual shale beds are 2 to 8 cm thick. Some shale beds grade upwards into very fine grained black sandstone. Within Meed Creek, between Gramophone and Reiseter Creeks, 30 m of exposed sediments are lithologically different from those described above. Here the sandstones are dominantly pink and are interbedded with heterolithic conglomerate (Plates 2 and 3; sections 5 and 6 in Appendix B). These rocks may be part of the underlying Bowser Lake Group. Sandstone (sample J89-050-04 in Appendix C) in Meed Creek is poorly sorted, medium grained volcanic arenite with angular to sub-rounded clasts of volcanic rock fragments (50%), quartz (15%), chert (20%) and plagioclase (10%) with lesser sedimentary rock fragments (5%), cemented by authigenic quartz. Canyon Creek  To the south of Reiseter and Gramophone Creeks in Canyon Creek (Fig. 2), sediments consist of interbedded fine grained sandstone, shale and siltstone at least 600 m thick (Fig. 6 and sections 7 to 10 in Appendix B). Upper and lower contacts are not exposed in this area. Thin to thick bedded sandstone in Canyon Creek is green on both fresh and weathered surfaces. Normally graded sandstone beds are micaceous and locally carbonaceous with organic matter occurring as disseminations, blebs (4 mm in diameter) and layers (1 mm thick) and rarely as single larger pieces (5 x 15 mm) Limonite stained bands (2 mm thick) and blebs also occur within this unit; limonite bands may be parallel to or cross cut carbonaceous layers. The sandstone sometimes alternates between hard (10 to 20 cm thick) and friable, fissile (6 to 20  27  Plate 2 - Conglomerate (upper photo) and sandstone (lower photo) from the Meed Creek area. Scale bar is 2 cm long.  28  Plate 3 - Photomicrographs of the sandstone in plate 2. Upper photo planepolarised light, lower photo crossed nicols; magnification x 256.  29  Figure 6: Composite section for Skeena Group sediments exposed in Canyon Creek. The symbols below are used in all subsequent stratigraphic sections unless otherwise stated.  LEGEND FOR STRATIGRAPHIC SECTIONS IN4 A 4 & '^4 4 9 1)4 4 C.41>44 4  v1. 7 h  Breccia  Shale  Clast supported  Coal  conglomerate s).2.• (7 : • ci- : 0 . :0 ••• ••• • 6 ': 9 : 0: : ,k: •*. -  -  •  .  .  :•  •  .  .  .  Cover  Matrix supported conglomerate  Fossils  Pebbly sandstotic^  Sandstone^  Siltstone^  RESISTANCE:  —^  Rip up clasts  \\\\* \\\\.^Cross-bedding  Breccia Conglomerate Coarse grained Medium grained Fine grained Shale  Sandstone  30 metres  600-  f••■••■••■■=1.  500-  100-  • .  •  •.•  .  • .•  , .., • • ... . . •• . •• ,•. ••••• .......... ..••^.^•.^..^• ••••^•••••••  : ..  400-  .•  ID-----  .  ...  \1  •...  ..^.  ---  ••• • —•—..:=. ..7  300 -  = 200-  Figure 6 -  17!ElE153571  1  31  cm thick) beds that are rarely finely laminated ( <1 mm thick lams.) or show vague ripple marks. Massive sandstone outcrops often fine upwards and vary from 1.5 to 33 m thick. Sandstones (samples J89-014-02 and J89-004-01 in Appendix C; Plates 4 and 5; Table 3) from the Canyon Creek area are moderately sorted volcanic and chertarenites with sub-angular clasts. Volcanic-arenites are composed of volcanic rock fragments (30%), quartz (40%) and chert (20%) in a quartz cement; chert-arenites are composed of chert (45%), quartz (25%), volcanic rock fragments (20%) and sedimentary rock fragments (10%) in a clay and chlorite matrix. Thin to thick bedded shale in Canyon Creek is black, sandy and micaceous occasionally with symmetrical ripple marks. This unit varies from 3 to 33 m thick. Shale also occurs interbedded with siltstone. This interbedded unit is 3 to 6 m thick with individual shale beds from 5 to 25 cm thick and siltstone beds from 6 to 15 cm thick. The siltstone within this unit is black and sometimes siliceous. Rip up clasts of siltstone and shale often occur within the siltstone beds. Bulkley Valley and Telkwa Area  Cretaceous sediments in the Bulkley Valley and Telkwa areas (Fig. 2) are dominated by fine clastics. In the Telkwa area, Cretaceous sediments in drill core are at least 500 m thick and rest unconformably on Haze1ton Group volcanic rocks (Palsgrove, 1990). Surface exposures in the Telkwa area are predominantly composed of interbedded fine grained sandstone and mudstone that are very thin to thick bedded (sections 11 to 13 in Appendix B). Coal occurs in the Telkwa and Lake Kathlyn areas where there are up to twenty coal seams with a maximum individual thickness of 4 m (Palsgrove, 1990). On Hudson Bay Mountain about 50 m of chert pebble conglomerate sits unconformably on volcanic rocks of the  32  Plate 4 - Sandstone exposed in Canyon Creek. Scale bar is 2 cm long; yellow grains are stained potassium feldspar.  33  Plate 5 - Photomicrographs of the sandstone in plate 4. Upper photo planepolarised light, lower photo crossed nicols; magnification x 110.  34  Haze1ton Group. This conglomerate is thick bedded with individual beds fining upward from pebble sized clasts to coarse sandstone. In the Bulkley Valley - Telkwa area sandstone is dominantly fine grained with minor medium grained sandstone. Both fresh and weathered surfaces are green. The sandstone is micaceous and has carbonized wood fragments and organic rich laminations ( < 1 mm thick) and some concretions. Occasionally interbedded with the fine grained sandstone is silty sandstone which is well laminated with individual laminations less than 1 mm thick and a millimetres scale of interlamination. Overall sandstone beds vary from 0.05 to 0.43 m thick; silty sandstone beds average 0.30 m thick. Interbedded sandstone and silty sandstone sequences average 4 m thick. Sandstone (sample J89-001-01 in Appendix C, Table 3) from this area is moderately well sorted, very fine grained volcanic arenite with sub-angular to subrounded clasts of quartz (7%), chert (20%), metamorphic rock fragments (59%), volcanic rock fragments (7%) and sedimentary rock fragments (2%). Thin to thickly bedded (0.15-1.52 m) mudstone, in the Bulkley Valley Telkwa area, is dark blue-grey and micaceous. Occasionally the mudstone is thickly laminated with dark grey, medium grey, pale grey and brown or brown and pale grey stripes 3 mm thick. Rarely the mudstone is thinly laminated with laminations less than 1 mm thick. Siltstone in this area is dark grey, micaceous and finely laminated with organic rich laminations 1 mm thick spaced 2 mm apart, there are also abundant carbonized wood fragments (2 x 2 mm). Siltstone units average 2 m thick. Coal measures are also found in the Bulkley Valley - Telkwa area. Rarely very fine grained volcanic (?) rocks are interbedded with the sediments (Plates 6 and 7).  35  Plate 6 - Volcanic rock (?) found interbedded with Skeena Group sediments in the Bulkley River at Smithers. Scale bar is 2 cm long.  36  Plate 7 - Photomicrographs of the rock in plate 6. Upper photo plane-polarised light, lower photo crossed nicols; magnification x 256.  37  Houston Tommy and Denys Creeks, Morice River and Lake Areas  South and west of Smithers in the Houston Tommy Creek, Denys Creek, Morice River and Lake area (sections 14 to 18 in Appendix B) Cretaceous sediments are similar to those in the Canyon Creek and Telkwa areas. These sediments include interbedded sandstone, siltstone, shale and coal with rare pebbly sandstone beds. In upper Houston Tommy Creek a minimum of 400 m of fining upward Skeena Group sediments are juxtaposed by faulting next to Hazelton Group volcanic rocks (Fig. 7). Cretaceous sediments exposed in Denys Creek are a minimum of 65 m thick and include several coal seams (Fig. 8c). In lower Houston Tommy Creek and the Morice River-Lake area, Cretaceous sediments are a minimum of 90 m thick (Figs. 7 and 8a and b; Plate 8). In the above areas the sediments are carbonaceous and sandstones are locally argillaceous. Sandstone and siltstone are very thin to very thick bedded, shale is very thick bedded. In this area sandstone is medium grained, green to pale grey in colour and siliceous, often with carbonized wood fragments and concretions (up to 40 cm in diameter). Occasionally chert and feldspathic volcanic pebbles (max. 3 cm in diameter) and rarely plant fossils occur within the sandstone beds. This sandstone unit varies from 0.15 to 36 m thick. Towards Denys Creek the sandstone becomes micaceous and siltstone lenses and planar laminations can be seen within the sandstone beds. South towards Morice River and Lake the sandstone is also planar laminated but is finer grained and has rip up clasts of siltstone and laminations and disseminations of organic matter. Sandstones in this area (samples J89-282-08, J89-065-01, J89-070-01 and J89019-01 in Table 3 and Appendix C; Plates 9 and 10) are primarily fine to very coarse grained, poor to moderately well sorted chert-arenites that have an average composition of quartz (35%), chert (45%), volcanic rock fragments (10%) and lesser sedimentary rock fragments, plagioclase and metamorphic rock fragments  38  meters  90-  0 -  Figure 7 - Composite stratigraphic section for Skeena Group sediments (Red Rose  division) exposed in Houston Tommy Creek.  -  39  meters  92—  50-  0  60-  •  40-  • -  • - • _ ^  •  • • .^•^•  • .^• • . • • • • • • ^•^• : . '  20 -  -  .  ,  .  .^......  20 -  -  -  -  -  -  10-  • •.  _1' .17...7."  0  .  . •  .  •  •  .• • •'^•  Figure 8 - Sections measured through Skeena Group sediments (Red Rose division). a). Near Morice Lake, b). near Morice River and c). near Denys Creek.  40  Plate 8 - Interbedded sandstone and shale exposed in lower Houston Tommy Creek (upper photo). Chert rich sandstone exposed in upper Houston Tommy Creek. Scale bar is 2 cm long.  41  Plate 9 - Sandstone from the Morice Lake area. yellow grains are stained potassium feldspar. Scale bar is 2 cm long.  42  Plate 10 - Photomicrographs of the sandstone in plate 9. Upper photo planepolarised light, lower photo crossed nicols; magnification x 256.  43  and rare orthoclase. Chlorite cement (up to 25% of the rock) dominates with minor chert cement and a silt and clay matrix (2-5% of rock). Occasionally the sandstone has a carbonate matrix which can be up to 15% of the rock (Sample J89-070-01). Rarely the sandstone from this area is fine grained, moderately sorted feldspathic volcanic arenite (Sample J89-067-01) with angular to sub-rounded clasts of volcanic rock fragments (30%), quartz (30%), chert (15%), plagioclase (10%), orthoclase (10%) and lesser sedimentary rock fragments (5%) in a silt and clay matrix (20% of rock). Siltstone within the interbedded siltstone and sandstone unit is dark grey, micaceous and planar laminated with laminations 2 mm thick. This interbedded unit is up to 18 m thick, with individual siltstone beds 2.4 m thick and sandstone beds 0.75 to 3 m thick. In the Denys Creek area individual beds are thinner, with siltstone beds 2 cm thick and sandstone beds 2 to 4 cm thick. In the Houston Tommy Creek area the interbedded sandstone is medium grained, white in colour and has rip up clasts (10 x 5 mm) and laminations and lenses of mud; burrows are seen on bedding planes. Shale occurs mainly interbedded with sandstone. Shale beds average 2 to 4 m thick and sandstone beds 0.3 to 1 m. Shale is dark grey-brown and weathers pale grey, dark grey or rust and is occasionally micaceous. In the Houston Tommy Creek area sandstone interbedded with shale is made up or layers of concretions (max. 40 cm diameter). Elsewhere the sandstone has angular rip up clasts, laminations and lenses of mud. Coal seams up to 0.5 m thick are exposed in Houston Tommy and Denys Creeks. In Denys Creek the coal weathers pale grey, is brittle and highly fractured and folded. In Houston Tommy Creek the coal is banded with alternating bands of bright (15%) and dull (85%) coal. Bright bands are 1 cm thick, dull bands are 1.5 to 3 cm thick.  44  Tahtsa, Ootsa and Francois Lakes Area  South of Smithers in the Lakes District, Cretaceous sediments are similar to those in the areas described above. In this area Cretaceous sediments are poorly exposed except on the south shore of Tahtsa Lake where 600 to 900 m of sediments are visible on Swing Peak and Laventie Mountain. These sediments comprise fine to medium grained carbonaceous and argillaceous sandstone and fossiliferous mudstone (Duffell, 1959). Overall the sediments gradually coarsen upwards from mudstone beds 20 to 30 m thick at the base through interbedded mudstone and sandstone to 5 to 60 cm thick sandstone beds at the top (Duffell, 1959). Volcanic breccias of the Kasalka Group conformably (Duffell, 1959) or unconformably (MacIntyre, 1985) overlie the Cretaceous sediments. Although the lower contact is not exposed it is believed (MacIntyre, 1985; Duffell, 1959) the sediments sit unconformably on the Hazelton Group. Sandstone in the Tahtsa Lake area is dark grey green, brown green or green, micaceous and planar bedded with rip up clasts and black siltstone laminations. Laminations are 0.01 to 2 cm thick and spaced 0.02 to 50 cm apart; planar laminations dominate with fewer convolute laminations. Trace fossils in the form of burrows(?) 1 cm wide can be seen on the base of beds. In the Swing Peak area (Fig. 9) the sandstone is overlain by conglomerate which coarsens upwards to a maximum clast diameter of 15 cm. Most clasts are rounded and clast composition includes siltstone, chert and volcanics. This conglomerate grades up into breccia of the overlying Kasalka Group. Sandstone (sample J89-077-03 in Appendix C, Table 3) from the MacDonald Landing area is fairly well sorted, fine grained chert-arenite with sub-angular to subrounded clasts of quartz (10%), chert (50%), volcanic rock fragments (14%) and sedimentary rock fragments (15%) in a calcite matrix (30% of rock).  •  45  meters a 4V V^4  a  'I 1  4 V^4  4 4 6  120-  4^t" A 4  ic, c, v°^4  t>^4^A 4 1:)• 4 V  scz) 0 cm Ct) CD 0 0 c 0 0  a  o .c:. 4, c. •C 4:1 • o o . p 0 co 0 ^  • ^  .^.^• . • •^• .  •• •. . • • • •* • •.^  80-  . go  I=1  40.^. . • • . .. OM •  .^.^.  • ........  — —.— — • —  0  • • •^. I . :^. Mb . ao  Figure 9 Stratigraphic section measured through Skeena Group sediments (Red -  Rose division) exposed on Swing Peak.  46  AGE, PROVENANCE AND DEPOSITIONAL ENVIRONMENT Age Cretaceous sediments within the northern Chilcotin-Nechako region are part of the Skeena Group as defined by Tipper and Richards (1976) and Tipper (1976) and shown in figure 10. Tipper (1976) suggested an age range of Hauterivian to Albian and/or younger for rocks of the Skeena Group in the Smithers area. The majority of samples collected during this study are lithologically similar to those of the Red Rose division (Fig 10) whose age Tipper (1976) suggested to be middle Albian. Results of palynological analyses for samples collected during this study give an age range of Aptian-Albian to Late Albian-Early Cenomanian (Table 4; Appendix D). Therefore, the age range of the Red Rose division can be expanded from middle Albian, as suggested by Tipper (1976) to Aptian-Albian to Late Albian - Early Cenomanian. The oldest sedimentary rocks of the Red Rose division, found in the study area, occur in Canyon Creek. Here an exposure of shale interbedded with siltstone and fine grained, micaceous sandstone yielded an age of Aptian-Albian based on palynomorphs (sample J89-017-02 in Appendix D and Table 4). Other samples from Canyon Creek and nearby Bulkley River yielded Albian ages (samples J89014-05 and J89-279-05, Appendix D and Table 4). South and west of Canyon Creek non-micaceous shale samples from upper Houston Tommy Creek (samples J89-282-01, 283-01 and 284-01, Appendix D and Table 4) yielded an age range of mid to Late Albian; samples 282-01 and 283-01 are mid to Late Albian and sample 284-01, which is higher in the section, is Late Albian. Skeena Group sediments of unknown age, exposed in lower Houston Tommy Creek, are similar to those exposed in upper Houston Tommy Creek, however they are highly micaceous. West of Houston Tommy Creek in Denys Creek micaceous siltstones interbedded with sandstone and coal (samples J89-263-  47  Brian Bow Formation  Albian &/or younger  - Varicoloured porphyry tuff, breccia & flows. - Coarse breccias of andesitic to dacitic composition.  Red Rose Formation  - Black to dark grey shale, chert pebble conglomerate & minor micaceous greywacke. ^  C .  Middle Albian  CC . 7) - Micaceous greywacke, black to dark grey shale,^ 0 .5 minor conglomerate & coal.^ 1 a) 1:3 -  CC  Hauterivian (?) to Albian (?)  Hauterivian to (?) Albian  Rocky Ridge Volcanics  - Dark green to rusty brown augite porphyry flows & breccias, rusty red tuff and breccia, hornblende andesite, aphanitic basic flows.  Kitsun Creek Sediments  - Coarse to fine polymict conglomerate, greywacke dark grey shale, coal; minor rusty red tuff related to Rocky Ridge Volcanics  Figure 10: The Skeena Group as defined by Tipper (1976).  48  Table 4 Palynology data for the northern Chilcotin-Nechako Region. -  49 SAMPLE J89 -282-1 (Houston Tommy Creek) AGE: Mid to Late Albian ENVIRONMENT: Terrestrial with minor marine influence PALYNOMORPHS: Cicatricosisporites hughesi Fern and Lycopod Spores Concavisporites granulatus Cyathidites minor Deltoidospora rhytisma Baculatisporites comaumensis Gleicheniidites senonicus Deltoidospora psilostoma Cicatricosisporites augustus  Distaltriangulisporites perplexus Appendicisporites problematicus Gymnosperm Pollen (incl. conifers)  Alisporites bilateralis  Angiosperm Pollen  Tricolpites micromurus  Dinoflagellate and other algal spores -  Pareodinia ceratophora Pseudoceratium regium Pareodinia sp.  SAMPLE J89-284-01 (Houston Tommy Creek) AGE: Late Albian ENVIRONMENT: Near shore marine PALYNOMORPHS: Fern and Lycopod spores Baculatisporites comaumensis Cicatricosisporites annuilatus Microreticulatisporites uniformis Cicatricosisporites cf. Anemia exilioides  Gymnosperm Pollen (inc. conifers)  Alisporites minutus Alisporites grandis Cupressacites hiatipites  Angiosperm Pollen  Tricolpites micromunus Scalariform angiosperm vessel  Dinoflagellate and other algal spores -  Lejeunia striata cf. Trithyriodinium rhomboideum cf. Apteodinium sp.  50 SAMPLE J89-283-01 (Houston Tommy Creek) AGE: Mid to Late Albian ENVIRONMENT: Near shore marine PALYNOMORPHS: Fern and Lycopod spores -^Concavissimisporites punctatus Cicatricosisporites imbricatus Gynmosperm Pollen (inc. conifers) Dinoflagellate and other algal spores -  Cerebropollenites cretaceus Cedripites cretaceous Alisporites spp. cf. Ascodinium verrucosum Cyclonephelium eisenacki Pseudoceratium regium Oligosphaeridium sp. Cyclonephelium cf. clathromarginatum  SAMPLE J89-263-01 (Denys Creek) AGE: Late Albian to Early Cenomanian ENVIRONMENT: Terrestrial with minor marine influence. PALYNOMORPHS: Gymnosperm Pollen^Cedripites cretaceus Alisporites grandis (inc. conifers)^ Angiosperm Pollen^cf. Trilcopites crassimurus Trilcolpites minutus Dinoflagellate and other algal spores -  Gardodinium eisenacki Pseudoceratium regium  SAMPLE J89-266-01 (Denys Creek) AGE: Mid to Late Albian ENVIRONMENT: Terrestrial with a minor marine influence. PALYNOMORPHS: Fern and Lycopod spores - ^Distaltriangulisporites irregularis Gleicheniidites senonicus Distaltriangulisporites perplexus Klukisporites foveolatus Cicatricosisporites imbricatus Gymnosperm Pollen  Cerebropollanites mesozoicus Spheripollenites scabratus Alisporites bilateralis Cedripites cretaceous Cupressacites hiatipites  Angiosperm Pollen (inc. conifers)  Tricolpites crassimurus  Dinoflagellate and other algal spores -  Gonyaulacysta sp. B Gonyaulacysta orthoceras  51  SAMPLE J89-017-02 (Canyon Creek) AGE: Aptian/Albian ENVIRONMENT: Open marine. PALYNOMORPHS: Dinoflagellate and other algal spores cf. Aptea polymorpha Apteodinium sp. Gonyaulacysta sp. Gonyaulacysta sp. A  SAMPLE J89-014-05 (Canyon Creek) AGE: Albian ENVIRONMENT: Near shore marine PALYNOMORPHS: Gymnosperm pollen (inc. conifers) Dinoflagellate and other algal spores -  Cedripites cretaceus  Apteodinium reticulatum Pareodinia ceratophora  SAMPLE J89-279-05 (Bulkley River in Smithers) AGE: Albian ENVIRONMENT: Terrestrial with minor marine influence PALYNOMORPHS: Fern and Lycopod spores -^Distaltriangulisporites perplexus (or  Deltoidospora diaphana Distaltrianglisporites irregularis Microreticulatisporites uniformis  Dinoflagellate and other algal spores -  cf. Hystrichokolpoma ferox Pareodinia ceratophora  costatus)  52  01 and J89-266-01, Appendix D and Table 4) yielded an age range of mid Albian Early Cenomanian; sample 263-01 has an age of Late Albian - Early Cenomanian and sample 266-01 is mid to Late Albian. The age of sediments exposed in Reiseter Creek is poorly constrained. A shale exposure (sample J89-006-07, Appendix D) yielded a possible age of mid to Late Albian, but this sample did not contain sufficient diagnostic palynomorphs to give a definitive age. There are some lithological and depositional similarities to the lowermost sediments described in the Telkwa area (Unit I, Fig. 11) or to the Kitsun Creek sediments described by Tipper (1976) therefore the sediments exposed in Reiseter Creek could be Lower Albian or older. Samples from sediments exposed in Gramophone Creek do not contain any palynomorphs and their age is unknown. Samples collected by Palsgrove (1990) from drill cores of Skeena Group sediments in the Telkwa area give palynological ages of Albian (or Barremian) to mid to Late Albian. Marine bivalves found in the drill cores are probably Albian but may be as old as Barremian (Palsgrove, 1990). Plant fossils found in Skeena Group sedimentary rocks in the Telkwa coalfield were dated as Early Cretaceous by Hacquebard et al. (1967). Thus, Skeena Group sediments in the Telkwa area range in age from Barremian (?) to Late Albian. No ages are known for sediments exposed in the Morice Lake area but they are lithologically similar to sediments of the Red Rose division. Volcanic rocks, lithologically and age equivalent to the Kasalka Group are also exposed in this area; thus the surrounding sediments may represent the upper portion of the underlying Red Rose Formation. These sediments are also lithologically similar to the uppermost sediments in the Telkwa area (Unit IV, Fig. 11). In the Lakes District, basal mudstones on the south shore of Tahtsa Lake contain marine invertebrate fossils including two varieties of ammonites :  UNIT IV  - Chloritic green sandstone (transgressive lag), overlain by silty mudstone - Deposited in a marine to nearshore environment  - 150 m thick Marine Transgression  mid to Late Albian  UNIT III - 90 m thick  Albian or Barremian  UNIT II  - Bioturbated or rippled, chert & muscovite rich sandstone, siltstone, carbonaceous mudstone and thick coal. - Deposited in a near shore to transitional marine environment  - Silty mudstone - bioturbated or cross-bedded, chert and muscovite rich sandstone, rare coaly mudstone.  - 140 m thick  - Deposited in a deltaic/shallow marine environment. Marine Transgression - Conglomerate, sandstone, mudstone and coal.  UNIT I  - Deposited in a braided fluvial environment.  - 100 m thick  Figure 11: Section through Skeena Group sediments in the Telkwa area all thicknesses are minimum. Information from Palsgrove (1990)  54  Sonneratia (Sonneratia) ex. gr. kitchini Spath and Sonneratia (Cleoniceras) ex. aff. pereziana (Whiteaves) which led Duffell (1959) to suggest an Early Albian age.These fossils were re-examined by Mclearn (in Jeletzky and Tipper, 1968) who interpreted their age to be mid Albian. Provenance  Structures that provide paleocurrent information are rare within the Skeena Group in the northern Chilcotin-Nechako region and insufficient evidence was found to give any conclusive paleocurrent directions. However, sparse paleocurrent data indicate flow from the east (this study and Tipper and Richards, 1976). Muscovite is present throughout the Red Rose division of the Skeena Group and probably reflects detrital influx from the high grade metamorphic rocks of the Omineca Belt to the east; the Omineca Belt was undergoing rapid uplift during the mid Cretaceous as a result of the collision between Stikinia (Composite Terrane I) and the North American craton in the mid Jurassic (Parrish, 1979; Eisbacher, 1981; Monger et al., 1982). Basal sediments of the Skeena Group (Kitsun Creek sediments and lower Red Rose division) are composed primarily of volcanic rock fragments and quartz with minor chert indicating a dominantly volcanic rich source area until Early Albian time when there was an increased influx of chert detritus. Kitsun Creek sediments and lower Red Rose division sediments are relatively enriched with texturally and mineralogically immature sediments suggesting the volcanics were derived locally, from nearby Hazelton Group strata or Hauterivian (?) to Albian (?) Rocky Ridge volcanics. The composition of sediments in the middle to upper Red Rose division is dominated by chert, probably reflecting increased clastic influx from the Cache Creek Group exposed to the east during uplift of the Pinchi Belt-Columbian Orogen  55  (Tipper and Richards, 1976). Sediments of the Red Rose division exposed in Houston Tommy Creek contain both reworked and first cycle sedimentary rock fragments which may have been derived from the Jurassic Bowser Lake Group. Sediments in the upper (?) Red Rose division appear to have an increased volcanic component over those of the middle Red Rose division, possibly due to contemporaneous volcanism. The Kasalka Group volcanics, believed to be correlative with the Brian Born Formation, range in age from 105 (MacIntyre, 1985) or 93 (Woodsworth et al., 1983) to 87 Ma. (MacIntyre, 1985). Therefore, active volcanism was occurring during deposition of the upper part of the Red Rose division. The presence of the Rocky Ridge volcanics and rare felsic volcanics interbedded with Albian sandstone and coal, in an outcrop exposed in the Bulkley River, suggest localized, intermittent, volcanism may have occurred throughout the deposition of the Skeena Group. Depositional Environment  Sediments exposed throughout the northern Chilcotin-Nechako region contain almost no sedimentary structures and most exposures are massive, hence there are few clues to the type of depositional environment. Because of the lack of sedimentary information the following discussion of depositional environment is based primarily on palynological data. Sediments exposed in Canyon Creek are fine grained with abundant organic matter in some exposures. Rare symmetrical ripples and the presence of organic matter in the lower part of the exposed section plus a palynologic assemblage that includes gymnosperm pollen and dinoflagellate and other algal spores (Sample J89014-05 in Table 4) suggests these Aptian-Albian sediments were deposited a near shore marine environment. Higher in the section fine grained sandstone interbedded with shale and siltstone (Sample J89-017-02) yielded a palynological  56  assemblage that contains only dinoflagellate and other algal spores suggesting an open marine environment of deposition (Table 4). East of Canyon Creek in the Telkwa area, Skeena Group sediments are known from drill core to be over 500 m thick and include conglomerate, sandstone, siltstone, mudstone and coal deposited during two regressive/transgressive cycles (Fig. 11; Palsgrove, 1990). The lower marine transgression is Albian (or Barremian) in age, the upper one is Late Albian or younger. Sediments exposed to the west in Canyon Creek may be correlative with the lower part of the section in the Telkwa area (Unit II, Fig. 11). South of Telkwa, in Houston Tommy and Denys Creeks, the presence of coal and abundant wood fragments within the sediments plus a palynomorph assemblage that includes fern and lycopod spores, gymnosperm pollen, angiosperm pollen, dinoflagellate and other algal spores indicates middle to Upper Albian Skeena Group sediments were deposited in a nearshore to transitional marine environment (Table 4). Palynomorphs from upper Albian shale exposed in Houston Tommy Creek (Table 4) point to deposition under nearshore marine conditions. This interpretataion is supported by an increase in the amount of shale and the absence of coal higher in the section. In Denys Creek upper Albian- lower Cenomanian sediments contain abundant carbonaceous material and have a palynomorph assemblage with a large proportion of fern and lycopod spores and gymnosperm pollen and a lesser proportion of dinoflagellate and other algal spores (Table 4) indicating deposition under transitional marine conditions. Based on age, sediments in Houston Tommy and Denys Creeks may correlate with the middle of the section known in the Telkwa area (Unit III, Fig. 11). However, there are some lithologic differences between the two; Skeena Group sediments exposed in Houston Tommy Creek have very little to no mica  57  whereas those in the Telkwa area are described as being muscovite rich (Palsgrove, 1990). Skeena Group sediments of unknown age are exposed in lower Houston Tommy Creek. These sediments consist of interbedded sandstone, siltstone and shale (Houston Tommy Creek section 1, Appendix B). Mud lenses, clasts and planar laminations are seen throughout the sandstone and burrows are found on bedding surfaces. The burrows shown in plate 11 are those of Thalassinnoides which prefer lower shoreface to offshore environments, and may also be found in low diversity brackish water suites (Lindholm, 1987, page 96). The above evidence is consistent with a nearshore marine/transitional marine environment as in upper Houston Tommy Creek. Upper Albian - lower Cenomanian sediments exposed in the Denys Creek area are lithologically similar to upper Albian or younger sediments in the Telkwa area; both are chloritic, green sandstones. However, in Denys Creek palynological evidence indicates deposition under transitional marine conditions whereas those in Telkwa were deposited under shallow marine conditions. North of Canyon Creek, sediments exposed in Reiseter Creek were deposited under fluvial conditions. These sediments (Reiseter Creek sections 1 and 2, Appendix B) consist of interbedded sandstone and shale; there are also lateral facies changes which cause interfingering of sandstone and shale. Sandstone locally forms fining upward channels that cut through the underlying shales. Lithologies in Gramophone and Reiseter Creeks are similar. Exposures in both creeks consist of shales cut by sandstone channels. In Gramophone Creek rare mudcracks and trace fossils occur on bedding planes indicating a possible mudflats depositional environment. In the Lakes District Albian sediments were deposited in a marine environment. Near Tahtsa Lake sedimentary rocks of the Skeena Group contain  58  Plate 11 - Thalassinnoides burrows exposed in lower Houston Tommy Creek.  59  poorly preserved shelly marine fauna and there are often trace fossils along bedding planes. Here Skeena Group sediments are unconformably (MacIntyre, 1985) or conformably (Duffell, 1959) overlain by breccias of the Kasalka Group. Overall most Cretaceous sediments within the northern Chilcotin-Nechako region appear to have been deposited in a nearshore marine to transitional marine environment, exceptions to this occur in Reiseter and Gramophone Creeks where the depositional environments appear fluvial. North of the Chilcotin-Nechako region correlative sediments in the Bowser Basin were deposited in a terrestrial environment (Cookenboo and Bustin, 1989) suggesting that the Smithers area may have been the northern limit of a mid Cretaceous sea. Marine conditions in the northern Chilcotin-Nechako region persisted until at least Late Albian - Early Cenomanian time after which widespread volcanism began (Kasalka Group and Brian Born Formation). D. STRATIGRAPHY OF CENTRAL CHILCOTIN NECHAKO REGION -  Within the central Chilcotin-Nechako region Cretaceous sediments are poorly exposed and often only outcrop in logging road cuts. In this area, Albian to Cenomanian (Table 5) sediments are known from well data (Fig. 12 and Sections 21 and 22 in Appendix B) to be at least 2800 m thick, however rarely more than 230 m are exposed at any one location (Sections 23 to 25 in App. B). Albian to Cenomanian sediments are overlain by 1400 m of Cenomanian (?) to Santonian volcanic rocks which are in turn overlain by 1700 m of Santonian to mid Eocene sandstone and shale. These sediments are capped by 580 m of mid Eocene to Lower Miocene volcanics.  60  Figure 12 - Subsurface stratigraphic sections compiled from well data. a) Nazko D-  96-E well (information from Canadian Hunter and this study) and b) Chilcotin B22-K well.  ^  Vr  DEPOSITIONAL^AGE ENVIRONMENT  Depth (in) 0 ---  Terrestrial  Early Miocene  ] Terrestrial  mid Eocene  500  7  Terrestrial Nearshore =  1000  11111111111  Late Eocene to Early Oligocene  II  Eocene (?) to mid Eocene  Terrestrial Maastrlchtian Transitional marine Open marine  I  Campanian  1500  Transitional-1^Santonian marine  2000  Volcanic Rocks  •  2500  Interbedded shale, conglomerate and sandstone  0• ILO  Interbedded conglomerate and sandstone with minor siltstone  1 <=  Interbedded conglomerate and shale with minor sandstone  ) 1  Interbedded sandstone and shale 3000  Shale with minor sandstone Sandstone with minor shale  3500  Open marinT1^] Albian — Campanian  Interbedded shale and pebbly sandstone Sandstone Shale  0: Mitn 111111111111!  0 :•1•:•:•VIC•VI•VVVV:.• ^Terrestrial ^ Nearshore 1 5 i:4 .•■■••■•■•■•■•■4 Open marine Nearshore Open marine ^  500  Tertiary Cenomanian latest Albian  Nearshore Marine  Terrestrial ^Nearshore ^ Terrestrial  74)^  1000  Nearshore Marine Terrestrial  CO  Late Albian 1500  Nearshore Marine ^ Nearshore Marine ^  0 2000  z Nearshore Marine 2500 Nearshore Marine ^ Terrestrial  3000 Cache Creek (?) /•••••• reelit • dna,  ••■••  11 Ii  late middle Albian  Aptian  62  Surface exposures examined in the Nazko area are Albian to Cenomanian in age (Table 5) and composed of interbedded chert pebble conglomerate and sandstone with lesser siltstone and shale (sections 27, 28 and 29 in Appendix B). Rusty to hematitic, red weathering conglomerate is clast to rarely matrix supported with a coarse grained sandstone matrix. Clasts are composed primarily of chert (up to 95%); pale grey chert is dominant with lesser black, milky, veined and red chert and white quartz (Plate 12). Sedimentary and volcanic clasts are rare. Sub-angular to rounded clasts range from 0.5 to 10 cm in diameter, averaging 2 to 5 cm. Conglomerate beds range from 0.5 to 6 m thick with an average of 1 to 2 m. These beds often fine upwards from cobbles and coarse pebbles to fine pebbles, some beds are lensoid in shape and form channels up to 6 m thick that cut through the underlying sandstone. Sandstone in the central Chilcotin-Nechako region is dominantly coarse to medium grained; lesser fine grained sandstone also occurs (Plates 13 and 14). Coarse grained sandstone is composed mainly of black and white chert and weathers rusty to greenish or white to cream, with pale grey to white fresh surfaces. Occasionally, chert clasts up to 2 cm in diameter outline planar beds 3 to 5 cm thick. Rarely, chert clasts are oriented parallel to cross-bedding. Micaceous, organic rich layers 1 cm thick occasionally occur within the coarse grained sandstone as do 5 cm thick fining upward sequences that grade from fine pebbles to coarse sand. Coarse grained sandstone beds vary from 0.5 to 3 m in thickness. Medium grained sandstone weathers rusty, pinkish, pale green brown or grey, fresh surfaces are dark grey and composed mainly of black and white chert. Planar lamination 1.5 cm apart, outlined by granules of chert occur within the medium grained sandstone beds as do flaggy beds with laminations 2 cm apart. Muddy lenses, organic matter and mica are also occasionally found within these beds. Rarely, 10 cm thick planar laminated beds of medium grained sandstone occur  63  Plate 12 - Chert pebble conglomerate (upper photo) and pebbly sandstone (lower photo) exposed in the Nazko area.  64  Plate 13 - Sandstone exposed in the Nazko area. yellow grains are stained potassium feldspar. Scale bar is 2 cm long.  65  Plate 14 - Photomicrographs of the sandstone in plate 13. Upper photo planepolarised light, lower photo crossed nicols; magnification x 819.  66  within the coarse grained sandstone. Medium grained sandstone beds vary from 0.5 to 3 m thick. Sandstone from the central Chilcotin-Nechako region (samples J90-005-03 and J90-004-01 in Appendix C) is composed of chert (24-50%), quartz (15-45%), volcanic rock fragments (5-15%), metamorphic rock fragments (5-10%), orthoclase (2-5%), plagioclase (0-3%) and minor sedimentary rock fragments in a chert cement with no to very little matrix and up to 10% porosity. Fine grained sandstone, siltstone and shale beds are recessive weathering and thus rarely exposed. Fine grained sandstone weathers rusty or grey, fresh surfaces are also grey. This sandstone is often carbonaceous and argillaceous with wisps of mud and organic matter throughout and tends to form friable beds 1 to 1.25 m thick. Siltstone beds weather rusty to medium grey and are dark grey on fresh surfaces. Siltstone forms friable beds up to 0.3 m thick: 0.1 m thick beds often occur within medium grained sandstone. Black shale beds weather rusty and tend to be sandy and carbonaceous, forming 1 m thick, highly friable beds. Overall exposures of Cretaceous sediments in the central Chilcotin-Nechako region weather rusty or a hematitic red colour and generally form 1 m thick fining upward sequences. Sediments within the Nazko D-96-E well consist of conglomerate, coarse to very fine grained sandstone, shale and siltstone. Conglomerate units vary from 2 to 80 m thick, pebbly sandstone units are 5 to 35 m thick, shale varies from 2 to 40 m thick, siltstone units average 2 m thick and interbedded sandstone and shale units are up to 300 m thick. In the Nazko D-96-E well conglomerate consists of sub-rounded, varicoloured (dominantly grey and black), pebble to granule size chert clasts in a coarse grained sandstone matrix. The conglomerate is poorly sorted, poorly consolidated and has no visible porosity. Coarse to very fine grained, poor to  67  moderately sorted sandstone in this well is grey, green, black or white. The sandstone is made up of sub-angular to sub-rounded grains of chert and quartz in a dominantly siliceous or carbonate cement. Mica occurs in some places, as do silty horizons. The sandstone has poor to no porosity. Shale in the Nazko well is black, brown, grey, green or maroon. The shale units are micaceous, silty, carbonaceous and iron stained in part. Floating quartz and chert grains occur in some places within the shale beds. The shale often grades to siltstone. Siltstone in this well is grey, micaceous and argillcaeous in part and has rare carbonaceous laminations. Iron staining occurs in some places. Siltstone units often grade to very fine grained sandstone. Sediments in the Chilcotin B-22-K well are made up of interbedded sandstone and shale. Sandstone is fine grained and brown, red, cream or grey in colour. This sandstone is carbonaceous throughout and quartzose in part. Minor mica occurs in the sandstones at the base of this sedimentary unit. Shale in the Chilcotin well is carbonaceous and black, dark grey, brown or mottled in colour. AGE, PROVENANCE AND DEPOSITIONAL ENVIRONMENT Age  Cretaceous sediments within the central Chilcotin-Nechako region are unnamed and are not part of any known group or formation. These sediments are however, lithologically similar and comparable in age to the Skeena and Battlement Ridge groups. Samples from the Chilcotin well range in age from Albian - Campanian to Early Miocene; samples from the Nazko well are Aptian to Tertiary (Table 5). Sediments in the Chilcotin well are Santonian (and older ?) to mid Eocene in age, those of the Nazko well are older and range from Aptian to Cenomanian. An outcrop sample from the Nazko area returned an age of mid to  68  Table 5 - Palynology data for the central Chilcotin-Nechako Region.  69 SAMPLE J90-006-03 (Honolulu Road, Nazko)  AGE: Mid to Late Albian ENVIRONMENT: Terrestrial (fern fen) PALYNOMORPHS: Fern and Lycopod spores^Krauselsporites linearis Distaltriangulisporites irregularis Klukisporites pseudoreticulatus cf. Schizaeosporites sp. (new) Cicatricosisporites efilioides (Maljavkina) Singh Cicatricosisporites imbricatus Foveotriletes subtriangularis Costatoperforosporites foveolatus Cicatricosisporites hallei Cicatricosisporites exilioides Cicatricosisporites augustus ? Biretisporites potoniaei PALYNOLOGY RESULTS FOR THE CHILCOTIN B-22-K WELL SAMPLE: 72.5m depth  AGE: Early Miocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Osmunda irregulites  Gymnosperm pollen (inc. conifers)  Pinus haploxylon Picea grandivescipites Cedrus perialata Pinus diploxylon Cupressacites hiatipites Podocarpidites sp.  Angiosperm pollen -  Araliaceoipollenites granulatus Myrica annulites Pterocarya stellatus  Fungal spores -  "Tetracellaesporites" sp. Vermiculate fungal spore  Dinoflagellate and other algal spores -  Schizosporis sp.  SAMPLE: 82.5m depth  AGE: Miocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen (inc. conifers)  Dinoflagellate and other algal spores -  Cedrus perialata Pinus haploxylon Cupressacites hiatipites Picea grandivescipites Glyatostrobus - type "Sectoridinium" sp.  70 SAMPLE 147.5m depth AGE: Miocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen (inc. conifers)  Cupressacites hiatipites Tsuga igniculus Pinus haploxylon  Angiosperm pollen -  Cupuliferoidaepollenites hiblarensis Graminacidites sp. Ouercoidites shiabensis Alnus undulosus  Fungal spores -  "Sphericites" sp. (new)  SAMPLE: 170m depth AGE: Miocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen (inc. conifers)  Cedrus perialata Cupressacites hiatipites Tsuga igniculus Pinus haploxylon  Angiosperm pollen -  Pterocarya stellatus Carpinipites ancipites Ouercoidites shiabensis  Fungal spores -  Sphericites sp. Multicellaesporites magnus  SAMPLE: 207.5 to 210m depth AGE: ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Deltoidospera diaphana Osmunda irregulites  Gymnosperm pollen (inc. conifers)  Cupressacites hiatipites Cedrus perialata  Angiosperm pollen -  Alnus vera Cupuliferoidaepollenites liblarensis Ouercoidites shiabensis Pterocarya stellatus Carpinipites ancipites Sabal granopollenites  71 SAMPLE: 222.5 to 230m depth AGE: Early Miocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Polypodiacea - forma - 1 Osmunda irregulites  Gymnosperm pollen (inc. conifers)  Cupressacites hyatipites Sequoiapollenites lapillipites Pinus haploxylon Pinus - 3 Cedrus perialata Picea grandivescipites  Angiosperm pollen -  Myrica annulites Paraalnipollenites confusus Carpinipites ancipites Ouercoidites shiabensis Cupuliferoidapollenites liblarensis Momipites coryloides Juglans nigripites  Fungal spores -  Inapertisporites "ellipticus"  SAMPLE: 317.5m depth AGE: Upper Eocene to Early Oligocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen (inc. conifers)  Keteleria - 1 Tsuga igniculus  Angiosperm pollen -  SAMPLE: 325 to 3375m depth AGE: Upper Eocene to Early Oligocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen (inc. conifers)  Angiosperm pollen -  Verrumonocolpites cf. parareolatus Cupuliferoidaepollenites liblarensis cf. Araliaceoipollenites granulatus  Cupressacites hiatipites Cedrus perialata Pinus haploxylon Keteleeria - 1 Sequoiapollenites lapillipites Picea grandivescipites Ericaceae - 1 Pterocarya stellata Cupuliferoidaepollenites liblarensis Gothanipollis - B Tilia cf. vescipites Araliaceoipollenites me_gaporifer Araliaceoipollenites granulatus  72 SAMPLE: 380 to 382.5m depth AGE: Mid Eocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Deltoidospora diaphana  Gymnosperm pollen (inc. conifers)  Tsuga igniculus Picea grandivescipites Pinus haploxylon  Angiosperm pollen -  Pistillipollenites mcgregorii Alnus vera  SAMPLE : 397.5 to 440m depth AGE: Mid Eocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Deltoidospora cf. diaphana Toroisporis sp.  Gymnosperm pollen (inc. conifers)  Keteleeria - 1 Cupressacites hiatipites  Angiosperm pollen -  Alnus vera cf. Pistillipollenites mcgregorii Ouercoidit es "ellipticus"  Fungal spores -  Dicellaesporites fusiformis  SAMPLE: 465 to 485m depth AGE: Eocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen (inc. conifers)  Angiosperm pollen Dinoflagellate and other algal spores SAMPLE: 505 to 535m depth AGE: Mid Eocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Pinus haploxylon Cedrus cf. perialata Picea grandivescipites Cupuliferoidaepollenites liblarensis Alnus vera Paleoperodinium ariadnae  cf. Distaltriangulisporites sp. (recycled)  Gymnosperm pollen (inc. conifers)  Pinus haploxylon  Fungal spores - ^  Microthallites lutosis  73 SAMPLE: 562.5 to 602.5m depth AGE: Mid Eocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen - ^Pinus diploxylon (inc. conifers)  Angiosperm pollen - ^Monosulcites sp. SAMPLE: 637.5 to 675m depth AGE: Mid Eocene ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm^ pollen - ^Pinus haploxylon Picea grandivescipites (inc. conifers) Cedrus perialata  Angiosperm pollen - ^Quercoidites "ellipticus" Alnus vera Fungal spores -^  Multicellaesporites attenuatus  SAMPLE: 717.5 to 720m depth AGE: Eocene? ENVIRONMENT: Terrestrial PALYNOMORPHS: Gymnosperm pollen - ^cf. Picea grandivescipites ^ cf. Pinus haploxylon (inc. conifers) Metasequoia papillapollenites SAMPLE: 740 to 782.5m depth AGE: Campanian to Maastrichtian ENVIRONMENT: Nearshore marine PALYNOMORPHS: Gymnosperm pollen - ^Pinus haploxylon (inc. conifers)  Angiosperm pollen - ^Proteacidites (Beaupreadites) thalmarnii Rhamnus minutapollenites Triporites rhamnoides Dinoflagellate and other algal spores -  SAMPLE: 807 to 967.5m depth AGE: Campanian to Maastrichtian ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  Areoligera senonensis Apteodinium sp. (?) Trithyriodinium evittii  Pilosisporites brevipapillosus Deltoidospora hallei  74 SAMPLE: 1052.5 to 1140m depth AGE: Campanian to Maastrichtian ENVIRONMENT: Terrestrial with minor marine influence PALYNOMORPHS: Fern and Lycopod spores - ^Liburnisporis adnacus Pustulatisporites sp. Polvpodiaceasporites forma 1  Gymnosperm pollen (inc. conifers)  Alisporites bilateralis  Angiosperm pollen -  Tricolpites microreticulatus  Dinoflagellate and other algal spores -  SAMPLE: 1200 to 1355m depth AGE: Campanian ENVIRONMENT: Open Marine PALYNOMORPHS: Dinoflagellate and other algal spores -  SAMPLE: 1395 to 1527.5m depth AGE: Indeterminate ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores -  cf. Chatangiella ditissima Trithyrodinium cf. suspectum  cf. Apteodinium cf. Alterbiadinium acuminata cf. Chatangella spectabilis  Deltoidospora diaphana (Triplano)  SAMPLE: 1940 to 2000m depth AGE: Santonian ENVIRONMENT: Terrestrial with minor marine influence PALYNOMORPHS: Gymnosperm^ pollen - ^Cedripites cretaceus (inc. conifers) Pityosporites (Pinus) alatipollenites Alisporites bilateralis  Dinoflagellate and other algal spores SAMPLE: 3490 to 3557m depth AGE: Albian to Campanian ENVIRONMENT: Open marine PALYNOMORPHS: Dinoflagellate and other algal spores -  Deflandrea cf. obscura  Cannigia minor  75 PALYNOLOGY FOR THE NAZKO D-96-E WELL  SAMPLE: 17.5 to 48m depth AGE: Tertiary ENVIRONMENT: Terrestrial PALYNOMORPHS: Fern and Lycopod spores Angiosperm pollen -  SAMPLE: 50 to 130m depth AGE: Cenomanian ENVIRONMENT: Nearshore marine PALYNOMORPHS: Fern and Lycopod spores Gymnosperm pollen (inc. conifers) Dinoflagellate and other algal spores -  SAMPLE: 135 to 190m depth AGE: Cenomanian ENVIRONMENT: Open Marine PALYNOMORPHS: Fern and Lycopod spores Dinoflagellate and othe algal spores -  SAMPLE: 195 to 220m depth AGE: Cenomanian ENVIRONMENT: Nearshore marine PALYNOMORPHS: Gymnosperm pollen (inc. conifers) Angiosperm pollen -  Cyathidites minor Ouercoidites microhenricii Stomatal app. Alnus vera  Gleicheniidites senonicus Alisporites rotundus  Pareodinia ceratophora Gonyaulacysta ettensa, Endoscrinium campanula  Deltoidospora hallii Broomea cf. jaegeri Endoscrinium campanula Pseudoceratium regium Odochitina costata  Cycadopites ovatus Psilatricolpites parvulus Psilatricolporites prolatus  76 SAMPLE: 230 to 247.5m AGE: Cenomanian ENVIRONMENT: Nearshore marine PALYNOMORPHS: Fern and Lycopod spores - ^Biretisporites potoniaei Angiosperm pollen -^Tricolpites crassimusus Dinoflagellate and other algal spores Pseudoceratium regium Dinopterygium cf. perforatum Apteodinium granulata  SAMPLE: 250 to 270.5m depth AGE: Cenomanian ENVIRONMENT: Open marine PALYNOMORPHS: Fungal spores Dinoflagellate and other algal spores -  recycled) SAMPLE: 290 to 345m depth AGE: Late Albian ENVIRONMENT: Nearshore marine PALYNOMORPHS: Fern and Lycopod spores Gymnosperm pollen (inc. conifers)  Multicellaesporites - H (new)  cf. Pseudoceratium regium Gonyaulacysta jurassica (probably recycled) cf. Pseudoceratium gochtii Gonyaulacysta jurassica var. longicornis (probably Scriniodinium cf. parvimarginatum  Deltoidospora hallii Gleicheniidites senonicus Tsugaepollenites mesozoicus  Dinoflagellate and other algal spores Pseudoceratium gochtii Gonyaulacysta cf. jurassica Chytroieasphaeridia chytroides Nannoceratopsis pellucida Gonyaulacysta nuciformis  77 SAMPLE: 350 to 380.5m depth AGE: Albian (r Late) ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -^Cicatricosisporites subrotundus  Distaltriangulisporites cf. mutabilus  Gymnosperm Pollen - ^Cupressacites hiatipites (Including conifers) Angiosperm Pollen - ^Paraalnipollenites alterniporus Tricolpites minutus Tricolpites crassimurus  Dinoflagellate and other algal spores -  SAMPLE: 385 to 460m depth AGE: mid to late Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores Dinoflagellate and other algal spores -  Gonyaulacysta jurassica Diconodinium galabrum Aptea polymorpha cf. Dictyopyxidia sp. Lejeunia pirnaensis Canningia minor  Deltoidospora hallii Cicatricosisporites hallei Diconodinium dispersum Gonyaulacysta cassidata  SAMPLE: 475 to 540m depth AGE: Barren SAMPLE: 555 to 637m depth AGE: mid Albian and younger ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores Angiosperm Pollen Dinoflagellate and other algal spores -  Impardecispora marylandensis Cicatricosisporites hughesi Alnus vera  Angio vessel end plate Gonuaulacysta cassidata  78 SAMPLE: 642.5 to 672.5m depth AGE: Late Albian to Early Cenomanian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -^Triporoletes sp. Distaltriangulisporites sp.  Gymnosperm Pollen - ^Callialasporites dampieri (Including conifers) Angiosperm Pollen -^Tricolpites minutus Dinoflagellate and other algal spores -  Gonyaulacysta extensa  SAMPLE: 699 to 712.5m depth AGE: Late Albian to Early Cenomanian ENVIRONMENT: Terrestrial PALYNOMOPHS: Angiosperm Pollen -^Tricopites crassimurus SAMPLE: 722.5 to 742.5m depth AGE: Albian, cf. Late ENVIRONMENT: Terrestrial TAI: PALYNOMOPHS: Fern and Lycopod spores -^Triporoaletes reticulatus Contignisporites cooksonii Distaltriangulisporites cf. mutabilis Cyathidites minor Couperisporites complexus Distaltriangulisporites costatus  Angiosperm Pollen -^Tricolpites micromunus SAMPLE: 802.5 to 817m depth AGE: Albian, cf. Late ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -^Dictyophyllidites sp. Appendicisporites bilateralis Contignisporites multimuratus  Angiosperm Pollen -^Tricopites crassimurus Cupuliferoidaepollenites minutus Clavatispollenites sp. Dinoflagellate and other algal spores -  Gonyaulacysta extensa Gonyaulacysta cassidata Pareodinia ceratophora  79 SAMPLE: 822.5 to 757.5m depth AGE: cf. Albian ENVIRONMENT: Terrestrial PALYNOMOPHS: Fern and Lycopod spores -^Radiatispora sp. Balmerisporites holodictyus Concavisporites parkinii Gymnosperm Pollen - ^Cedrus cretaceus (Including conifers) Dinoflagellate and other algal spores SAMPLE: 902.5 to 917.5m depth AGE: Late Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -  Angiosperm Pollen Dinoflagellate and other algal spores -  SAMPLE: 922 to 962.5m depth AGE: Late Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -  Gymnosperm Pollen (Including conifers) Dinoflagellate and other algal spores -  SAMPLE: 990 to 1,065m depth AGE: Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores Dinoflagellate and other algal spores -  Schizosporois cooksoni  Cyathidites minor Aeqrutriradites vanibilis Cicatricosisporites hallei Comperisporites tabrulatus Tricolpotes minutus Apteodinium reticulatum Apteodinium maculatum  Deltoidospora diaphana Deltoidospora rhytisma Cicatrocpsoprotes spiralis Cicatrocpsosprotes australiensis Alisporites bilateralis Cupressacites hiatipites Cycadopites follicularis cf. Cleistosphaeridium huguonoti Gonyaulacysta cf. hyalodermopsis  Cicatricosisporites australis Gleicheniidites senonicus  80  cf. Scriniodinium eurvphlum SAMPLE: 1,090 to 1,165m depth AGE: Late Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -  Angiosperm Pollen Dinoflagellate and other algal spores SAMPLE: 1,220 to 1320m depth AGE: Late Albian ENVIRONMENT: Terrestrial PALYNOMOPHS: Fern and Lycopod spores -  Biretisporites potonieae Cingutriletes clavus Cyathidites minor Cupulideroidaepollenites munutus Tricolpites crassimurus Scriniodinium eurvphlum  Cicatricosisporites hallei Cyathidites minor  Angiosperm Pollen -  Tricolpites crassimurus  SAMPLE: 1,365 to 1,405m depth AGE: Indeterminate - cf. Albian TM: 3.5 - 3.75 PALYNOMOPHS: Fern and Lycopod spores -  Deltoidospora diaphana  Gymnosperm Pollen (Including conifers)  Cycadopites ovatus  81 SAMPLE: 1,450 to 1,506m depth AGE: Late Albian ENVIRONMENT: Terrestrial PALYNOMOPHS: Fern and Lycopod spores - ^Kiukisporites reticulatus Appendicisporites erdtmanni Cicatricosisporites augustus Cicatricosisporites Pseudotripartitus Cyathidites minor Fovecosporites canalis  Angiosperm Pollen -^Tricolpites minutus SAMPLE: 1,505 to 1,625m depth AGE: Late Albian ENVIRONMENT: Nearshore marine TAI: 2.5-2.8 PALYNOMOPHS: Fern and Lycopod spores -^Osmundacidit es comaumenis  Gymnosperm Pollen - ^Alisporites bilateralis (Including conifers) Dinoflagellate and other algal spores -  Apteodinium reticulatum  SAMPLE: 1,805 to 1,895m depth AGE: Late Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -  Cyathidites minor  Gymnosperm Pollen (Including conifers)  Tsugaepollenites clampieri Pinus alatipollenites  Angiosperm Pollen -  Tricolpites crassimurus  Dinoflagellate and other algal spores -  cf. Canningia reticulata  82  SAMPLE: 2,270 to 2,400m depth  AGE: Late Albian ENVIRONMENT: Nearshore marine TAI: 25-2.8 PALYNOMOPHS: ^Cyathidites minor Fern and Lycopod spores -  Deltoidospora diaphana Lycopodiumsporites crassimacerius  Gymnosperm Pollen (Including conifers) Angiosperm Pollen -  ^Alisporites bilateralis  ^  Dinoflagellate and other algal spores -  Tricolpites crassimurus Chytroieasphaeridia sp. 1 Chytroieasphaeridia sp. 2  SAMPLE: 2,461 to 2,520m depth  AGE: Late Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores - ^Lycopodiumsporites austroclavidites  Cicatricosisporites venustus Deltoidospora diaphana  Gymnosperm Pollen^ - ^Alisporites bilateralis (Including conifers) Callialasporites sp. Dinoflagellate and other algal spores SAMPLE: 2,535 to 2,665m depth AGE: late middle Albian ENVIRONMENT: Nearshore marine PALYNOMOPHS: Fern and Lycopod spores -  Gymnosperm Pollen (Including conifers)  Apteodinium reticulatum  Lophotriletes babsae Aequaetriradites spinulosus Contigisporites sp. Deltoidospora diaphana Alisporites bisaccus Alisporites bialateralis Cycadopites elongatus  Dinoflagellate and other algal spores -  Chlamydoporella urna  83 SAMPLE: 2,782 to 2,817m depth AGE: Aptian ENVIRONMENT: Terrestrial PALYNOMOPHS: Fern and Lycopod spores -  Gymnosperm Pollen (Including conifers)  Tigrisporites Contignisporites glebulentus Lycopodiumsporites marginatus Lycopodiumsporites austroclavidites Aequaetriradit es spinulosus Podocarpidites ornatus Podocarpidites canadensis  SAMPLE: 2,835 to 2,967m depth AGE: Indeterminate SAMPLE: 2,980 to 3,120m depth AGE: Aptian ENVIRONMENT: Terrestrial PALYNOMOPHS: Fern and Lycopod spores Gymnosperm Pollen (Including conifers) SAMPLE: 3,130 to 3,292m depth AGE: cf.Aptian ENVIRONMENT: Terrestrial PALYNOMOPHS: Fern and Lycopod spores Gymnosperm Pollen (Including conifers)  Verrucosisporites Podocarpidites ornatus  Deltoidospora diaphana Alisporites bisaccus  84  Late Albian (sample J90-006-03 Table 5). Provenance  Cretaceous sediments in the central Chilcotin-Nechako region are similar to those of the northern Chilcotin-Nechako region; they are dominated by detrital chert and quartz with lesser amounts of volcanic and metamorphic rock fragments. As in the northern Chilcotin-Nechako region structures indicating paleoflow are rare, but suggest flow was from the east. The Cache Creek terrane is the probable chert source and the Omineca Belt the most likely source for any metamorphic detritus, especially mica which is abundant in sandstone in the Nazko area. The source of volcanic detritus is unknown. It may have been derived locally from surrounding Hazelton Group strata or possibly from contemporaneous volcanic rocks. The volcanic Spences Bridge Group and the informal Powell Creek formation, now exposed to the southeast, were deposited during Late Cretaceous to Cenomanian time and could have been a source of volcanic detritus. Cretaceous sediments in the Chilcotin B-22-K well appear to have a more dominant volcanic component than those in the Nazko D-96-E well which are composed primarily of chert and quartz. As the sediments in the Chilcotin well are younger than those in the Nazko well this increase in volcanic detritus may be due to increased proximal volcanic activity during their deposition. Volcanic activity is known to increase in both the northern and southern Chilcotin-Nechako region in Late Cretaceous time (Tipper and Richards, 1976; Maclntyre, 1985; Garver, 1989). Depositional Environment  Palynological data (Table 5) and information from geophysical logs for the Chilcotin B-22-K and Nazko D-96-E wells in the central Chilcotin-Nechako region indicates Cretaceous sediments were deposited under terrestrial, nearshore marine  85  and open marine conditions that varied through time (Fig. 12), possibly documenting the changing shoreline of a mid to Late Cretaceous sea. During periods of terrestrial deposition lithologic and well log data indicate the mid Cretaceous sediments of the Nazko well consist of numerous conglomerate and sandstone channels interbedded with shale. Interbedded shale and sandstone mark periods of marine to transitional marine deposition (Fig. 12). The younger sediments of the Chilcotin well are made up entirely of interbedded sandstone and shale which represent periods of terrestrial, nearshore marine and transitional marine deposition. Underlying these Santonian (and older ?) to mid Eocene sediments are Cenomanian (?) to Santonian volcanics, some of which (3490 to 3557 m depth) were deposited in a submarine environment (Table 5). Depositional environments for the remainder of these volcanic rocks are unknown due to their low palynomorph content. The mid Eocene to Lower Miocene volcanic rocks overlying the sediments in the Chilcotin well contain no palynomorphs indicative of marine deposition and are believed to be entirely terrestrial in origin. The presence of dinocysts (table 5) within the sediments of the Chilcotin and Nazko wells indicates marine conditions persisted until Maastrichtian time suggesting there may have been an open seaway in south central British Columbia at this time. E. STRATIGRAPHY OF SOUTHERN CHILCOTIN NECHAKO REGION -  Cretaceous sediments in the southern Chilcotin-Nechako region include the Relay Mountain, Jackass Mountain, Taylor Creek, Kingsvale and Battlement Ridge groups. Sediments of the Relay Mountain Group were deposited in Late Jurassic and Early Cretaceous time on the northeastern side of the Tyaughton Basin (Fig. 2; Tipper, 1969). Sedimentary and volcanic rocks of Early to mid Cretaceous age, that  86  unconformably overlie the Relay Mountain Group were deposited in the Tyaughton Basin and broader areas beyond the limits of the basin (Tipper, 1969). The Relay Mountain Group is discussed only briefly here; for a detailed description see Jeletzky and Tipper (1969) and Umhoefer (1989). The Jackass Mountain Group has been described by Jeletzky and Tipper (1968) and Kleinspehn (1982) and the Taylor Creek Group by Jeletzky and Tipper (1968) and Garver (1989). The Kingsvale and Battlement Ridge Groups are discussed at greater length here as they are believed to be correlative with Cretaceous sediments exposed in the central and northern Chilcotin-Nechako region. For a detailed description of the Kingsvale Group see Jeletzky and Tipper (1968) or McLaren (1990). The Battlement Ridge group is discussed by Glover et al. (1988), Garver et al. (1989), Schiarizza et al. (1989) and Garver (1989). Potato Mountain  Sediments of the Relay Mountain Group are exposed on Potato Mountain where they are about 320 m thick and comprised of fossiliferous (Buchia, Inocerami and belenmites), fine to very coarse grained sandstone and lesser conglomerate, shale and limestone (Fig. 13; Section 26 App. B; Plates 15 and 16). Sandstone is thin to very thick bedded with fossiliferous and non fossiliferous beds. Locally, very coarse grained sandstone beds fine up to fine grained sandstone; rarely the sandstone is arkosic. Sandstone from Potato Mountain (samples J90-011-01, 02, 03, 04, 05, and 08 in appendix C) is volcanic arenite composed of: volcanic rock fragments (46-75%), quartz (3-20%), chert (5-25%), metamorphic rock fragments (0-20%), plagioclase (0-10%), orthoclase (0-10%) and minor calcite (4%) in a dominantly chlorite and quartz cement with minor poikolitic carbonate and carbonate overgrowths in some samples.  87  meters .• •^'  200-  •  . • .  • 0 • • • • • . •^• •  400-  • •  •  •.• ^. ®•  • ••^.^. •  ,•c,c3.0  c, o 121 c) c. ° o c, 0 0 c) 0 0  00  160O  360-  c,  0  0  • •^•^• • . • •• • • •^0.^• • • • .•^• • • • • • • • 0 0:6.  320-  0 0 C?60 t=) 6.0  5:6 C0  ei•al ,=3•.=;^e.bc+.•" • citch4 4";q•••:‘,•■• . ..:° `= ^120 0 0 •10 CZ6 go 0 0 0  te  : .  •  r• -  • •^•  •^•^.  •  •  .^.  (F)  .^•^•^•^• • .^.^• * '^•^•  • .,^,^•^• . • . •^•^•  -  • • •M• • •^•^•^• „^. • •^•^• • • 0^• •  . .  •  •  c3.  .^. . .  •  .^. • • .^• •^• • • • •• • •  • •• •^• •  ■=1  o^• • • .2. • .^ •^ •^.2.  80-  .^. •  280-  ..  • • •• • • .• • .' •^."  .•^  40-  .^  .  240-  • .•  Figure 13 - Stratigraphic section measured through the Relay Mountain Group  exposed on Potato Mountain.  '4  •  88  Plate 15 - Very coarse grained sandstone of the Relay Mountain Group exposed on Potato Mountain. Scale bar is 2 cm long.  89  Plate 16 - Photomicrographs of the sandstone in plate 15. Upper photo planepolarised light, lower photo crossed nicols. Magnification x 110.  90  Conglomerate is clast to matrix supported with well rounded, dominantly volcanic clasts from 1 to 15 cm in diameter in a coarse grained sandstone matrix. The conglomerate is very thick bedded and clast supported beds often fine up into coarse grained sandstone. At the top of the section matrix supported conglomerate interbedded with coarse grained sandstone grades up into fine grained sandstone. Shale is thick bedded, carbonaceous and weathers recessively. Limestone and siltstone are rare and occur as thin interbeds within the sandstone. West of Mount Tatlow  A 500 + m thick section of Taylor Creek Group (?) sediments are exposed on a ridge west of Mount Tatlow (Fig. 2). These sediments are dominantly composed of interbedded sandstone and shale, shale and siltstone with lesser conglomerate, very coarse grained to coarse grained pebbly sandstone and medium grained sandstone (Fig. 14; Section 27 App. B; Plate 17). Conglomerate is abundant in the top of the section where it forms very thick bedded resistant cliffs up to 5.5 m high. Weathered surfaces are dark grey brown to rust and fresh surfaces are dark grey. The conglomerate is clast to matrix supported and has a fine to medium grained sandstone matrix. Clasts are rounded to subangular and range from 0.5 to 6 cm in diameter, there is locally a bimodal clast size distribution. Clast composition is dominated by chert (80%) with lesser granitic (3%), white quartz (5%), grey siltstone (6%) and green siltstone (4%). The conglomerate often forms repetitive fining upward sequences, 0.6 m thick, of conglomerate, sandstone and siltstone. Conglomerate beds frequently scour into the underlying sandstone; in some places siltstone fills depressions in the top of conglomerate beds. Sandstone is coarse to fine grained and weathers medium brown, dark to light grey or green - grey, fresh surfaces are dark to light grey,  -  -  91 •  300-  .. • „..„ • •, • „ ••• ..• • •^•^• • • • • • • . % • „^• • • . • • • • • • • • -r 7• . • . •  ;a • a.":45 VaitS.J ,  -  .  •  .  • .^• • . • • • • • • • .^.^•  •  .^: . • • • • • • : • •• • •  ••• • ••••g^—.  200500-  tqC"? alia„tt c'.. 4. 4!°,5? 4.-4? C:ASI"lai "•E•c:Tcz7c:s c=t 0C040•14G5-4:76a1  , ••. •. •• , • , • „ •^• • • • • ir ••••^ - ivin} v •ast,^-•••.-•••14b. Z•••■•••  ese,466, 6 a  .  ..  . •^. • ...  ./11,apc)  ••  •  • 0•t AM  •  Alb  ••^•^. • • • • • L. ..^ • . .•• • • • • • • • • • •^• • • • .  • • • •• •^- • • • • • • • •  ••  .■ • • • •^• • • • •  •  77:177 • • 7: •77 .7. r •^- T. •^•• • • • • • • •  •  • • . •^'. .• •.^••  •  0.^  ••  • . • .^• • • •••••••••••  . • • •^• •^% • • • • -  7-1- "."-.:= •  •_.• •^L^•  • • • •LI • • • 4  100-  . •• • . • • .• : • • : .•  400-  •  • •-.a - •^• :A^*=.'. • • . . • • . . • • •^• • - • .^•^. • . • -•^Z-*^•^"-a • •^ •-• • • ▪ •-•.. •^ •-- s- ••••^.7-•• ••-• • •-••.•• •-^•,:••• •-•- • -•^• • • • •^-I. • •  .^. •  • • •^• •  .  • •^• • • • • • • •  ; • •  •  • •  • •  •••^•• aL • •••  .^  : . : .•  . • • • •^• • •  ••• • • • • • • • • • • • • .• • • • . • • • • • 1. • • •  •  •  •  : ci c.;^•••  • • • o^• C" . •  2  . •^• .^• , •^: • • • .—;^7 • 7; .• • 7 . •^• •^• .^• • • , •^. , •^• • •^•^• .^•  •  0  Figure 14  -  Stratigraphic section measured through the Taylor Creek Group exposed  on a ridge west of Mount Tatlow.  92  Plate 17 - Interbedded conglomerate, sandstone and shale (upper photo). Fossil plant material in silstone (lower photo). Taylor Creek Group near Mount Tatlow.  93  grey - brown or green - grey. Coarse grained sandstone is thick to very thick bedded with beds from 0.6 to 5.3 m thick that may have up to 5% pebbles and often grade up to matrix supported conglomerate. Medium grained sandstone beds are thick to very thick bedded with beds from 0.85 to 1.85 m thick, fine grained sandstone beds vary from 0.85 to 6 m thick. Fine grained sandstone beds sometimes have planar or slightly wavy siltstone laminations 1 to 4 mm thick, are occasionally flaggy and rarely are made up of alternating laminations of dark grey and pale grey or light grey and dark green sandstone. Sandstone beds often fine upwards and have rip up clasts of siltstone or small chert clasts at the base, rarely the basal strata are cross-bedded or planar laminated. In some areas the sandstone has 4 cm thick siltstone interbeds within which are load casts of sandstone and burrows (Plate 18). Rarely seen within the sandstone are 2 cm thick bioturbated horizons, wavy bedding, or mica (biotite or phlogopite). Occasionally there are limey sandstone beds 10 to 20 cm thick with loaf shaped concretions 10 to 30 cm long (Plate 18). Sandstone (samples J90-038-02a, 038-13 and 039-04 App. C) in this area is volcanic arenite composed of: volcanic rock fragments (36-76%), quartz (4-40%), chert (1-15%), metamorphic rock fragments ( < 1-10%), sedimentary rock fragments (0-3%), plagioclase (5-10%), orthoclase (3-5%), calcite (0-2%) and pyroxene ( < 13%) in a quartz-chlorite cement with minor carbonate cement and rarely up to 50% carbonate matrix. Most of this section consists of interbedded sandstone and shale which varies from 4 to 43 m thick. In this interbedded unit the sandstone is fine to medium grained and weathers medium grey, pale grey or green - grey, fresh surfaces are dark brown - grey, pale grey or medium grey. Sandstone beds are thin to thick bedded varying from 0.3 to 0.75 m thick, are usually carbonaceous and occasionally thinly laminated. Rarely the bedding is wavy with undulations a maximum of 1 cm high.  94  Plate 18 - Calcareous concretions (upper photo) and burrows (lower photo) in the Taylor Creek Group exposed near Mount Tatlow.  95  Shale in this interbedded unit is fissile and weathers black or dark grey green, fresh surfaces are black - brown or dark grey. Shale beds are thin to thick bedded varying from 0.4 to 0.7 m thick. Occasionally the interbedded shale is planar laminated with laminations 1 mm thick. Siltstone is thin to very thick bedded with recessively weathering beds 0.2 to 2 m thick. Siltstone is usually carbonaceous and weathers medium green - grey or black, fresh surfaces are dark grey of black (Plate 17). Shale varies from 1 to 45 m thick, is fissile or less often splintery. Both fresh and weathered surfaces are black to dark grey. Taseko River  Cretaceous sediments of the Kingsvale Group are exposed beside Taseko River near Vick Creek (Fig. 2). Here the sediments comprise a 700+ m thick coarsening upward succession of clast to matrix supported conglomerate with dominantly volcanic and intermediate intrusive clasts, very coarse grained to medium grained pebbly sandstone with chert and volcanic pebbles, coarse grained to fine grained sandstone, coarse grained to fine grained breccia with feldspar porphyry clasts, siltstone, shale and mudstone (Fig. 15 and 16; Sections 28 and 29 App. B). Conglomerate in the Taseko River area is thin to very thick bedded, clasts to matrix supported and generally poorly sorted. Beds vary from 0.5 to 15 m thick. Rounded to sub-angular (mainly rounded) clasts vary from 1 to 50 cm in diameter and average 5 cm (Plate 19). Clasts are composed mainly of dark grey feldspar phyric or dark grey volcanics and black and white or pink intrusives with lesser laminated black and grey sedimentary and minor grey, white and pink chert pebbles. The matrix is coarse to medium grained white - green sandstone. Conglomerate beds are friable.  96  100  meters  o  c'cg.=.c)clz€,Ga°0=zg  c=, • cr CD •^C>.',.=, •  ;  X0 0  c  .4"  02 SEY6  , c.• 925 oy '2c c=,  c)  ,  4.1p Cb C:16  .10 .1.■ ...M. —^  4111•174•14, J  F  C.3) IP AI • go, eC:5€ C,CSC  aSioc=c ‘g9Gis  7  R301 1  0 0 .e?°a . - . • :s cz) o • . •^• •^• -• ••4=7 • o•.(2.0 .0. = •.;,—:-: • .Q . • .^•^. .  .  ,  ,  C3,4:Pek:300c2-,C2c:, 000Q,c3 c , Cc):3CDT00°  f:::: .41  ) 0Cc1 3 0 C. 0 0, ipa Cir;10 2c SO c3; L) °(7 ° -- 7 : ° r  ■0 C2 C3 OoPvo 0.,013,-°026@pc, 04,LboCgp, •a Figure 15 - Stratigraphic section measured through Kingsvale Group sediments  exposed on the east side of Taseko River, near Davidson Bridge.  I  97  meters  ••0• •• •• •••••  •■  :..te;-  *  •  120-  4^• t••^••  •  0 A^C• ^ • • A 4^P • G A • • •^4 4^a 4 e V •  4  "  80-1  40  :1  Igo  Figure 16 - Stratigraphic section measured through Kingsvale Group sediments near  the confluence of Vick Creek and Taseko River. This section lies below that in figure 15.  98  Plate 19 - Conglomerate (upper photo) and sandstone (lower photo) of the Kingsvale Group exposed near Davidson Bridge, Taseko River. Scale bar is 2 cm long. Yellow grains in sandstone are stained potassium feldspar.  99  Rarely, discontinuous coarse grained, green sandstone beds 0.2 to 0.4 m thick occur within the conglomerate beds. The lowest conglomerate beds exposed in this section show no grading and are poorly sorted. In the middle of the exposed section, conglomerate beds 1 m thick grade rapidly from matrix to clast supported and some of these beds have scoured bases. At the top of the section the conglomerate is better sorted and very few large clasts occur (the average clast diameter is still 5 cm but rare large clasts have a maximum diameter of only 15 cm). Very coarse grained to very fine grained sandstone weathers dark to pale grey, medium to pale brown or cream with rusty blebs, fresh surfaces are dark green to grey, medium to pale grey or white (Plate 19). Very coarse grained sandstone beds are often pebbly with rounded chert or less often sub-rounded volcanic clasts from 0.4 to 6 cm in diameter. These beds often fine upwards to non-pebbly very coarse grained or coarse grained sandstone forming repetitive fining upward sequences 0.2 m thick. Very coarse grained and coarse grained sandstone is often quartzose. Coarse grained sandstone often fines upwards into medium grained sandstone in 5 cm thick repetitive cycles. Very fine and fine grained sandstone often coarsens upwards to coarse or medium grained sandstone forming 0.3 m thick repetitive sequences. very fine to coarse grained sandstone is often carbonaceous and may be micaceous. Very fine grained sandstone beds are rarely finely planar laminated. Concretions 20 cm in diameter occur in some medium grained sandstone beds. Coarse grained sandstone may be cross-bedded with cross-beds outlined by darker layers or small clasts. Very coarse grained sandstone beds vary from 1.2 to 28.5 m thick, coarse grained sandstone beds from 3 to 16.5 m. Medium grained sandstone beds are 0.8 to 9 m thick and fine grained sandstone varies from 0.9 to 4.5 m thick.  100  Sandstone (samples J90-012-01, 03, 05 App. C; Plates 19 and 20) in the Taseko River area is volcanic arenite composed dominantly of volcanic rock fragments (40-56%) and quartz (25-35%) with lesser plagioclase (8-20%), chert ( < 1-5%), orthoclase ( < 1-6%) and metamorphic rock fragments (<1-5%) and minor pyroxene (<1-1%), calcite (0-1%) and chlorite (0-2%) in a chlorite and carbonate or chlorite and quartz cement. Recessive weathering shale is black with black to rust or white weathered surfaces. Shale beds are 0.5 to 1.6 m thick. Carbonaceous, thin to very thick bedded mudstone and siltstone are also recessive weathering. Mudstone weathers white to rust and fresh surfaces are medium grey. Siltstone weathers rusty, dark to medium grey or pale pink - grey, fresh surfaces are pale to medium grey, dark maroon - grey or dark grey - brown. Coarse to fine grained breccia is very thick bedded with beds ranging from 3.6 to 10.5 m thick. Weathered surfaces are purple - grey with rusty blebs and fresh surfaces are dark grey to green. Angular, maroon, green or feldspar phyric volcanic clasts, in a fine to coarse grained feldspathic sandstone matrix, vary from 2 cm to 4 m long. Breccia beds are over and underlain by a recessive weathering fine grained, maroon - grey feldspathic volcanic unit. Rare white, cream weathering ash beds occur within this section. These beds pinch and swell along bedding from 0.15 to 0.4 m thick. Chilko River  Twenty five metres of Cretaceous sediments are exposed in Chilko River. These sediments are made up of interbedded thin to very thick bedded medium grained sandstone and very thick bedded matrix supported chert pebble conglomerate with lesser pebbly sandstone (Fig. 17; Section 30 App. B). Micaceous, quartzose sandstone is well sorted and medium grained with hematitic red or  101  Plate 20 - Photomicrographs of the sandstone in plate 19. Upper photo planepolarised light, lower photo crossed nicols. Magnification x 256.  102  meters 25 -  ; •• C. •^ cP • •CY•O • • ^° .0 . • o' ^•0 • 0 ;co • • • •• . •  . 0 •^ o • p.. ^• 4 •^ 0•.o• . c .  ••  •o •o • • o ••o••  20  •  -  O. ' 0.*CD.• 0-^ C) • d • 0 • 0 • .  0^• • cl••.  15-  .  0 • •0 • ,^o  ..0  C) Q0•C)°9 (2.C?•j;'9.-0C2(.21 0  • O.  0 • ° • .0 ^•.0.0.  0  .^• •  10  •  •^• . •^• „,^.  •  •^• •  • •^•  -  • • * • • • • ..•o e . • • ar• • a• •^•=o^e=w .  .^.  •  5-  •  •^• . •  •^•^• . ' . .^'^•^•^•^. • • .^• •^•^. •^•^• • •^• • . • . • ,^ C,^• ,/:; •  ."..  (2 •  cy. c).  0.  .  b 0-.0 • c, • c. .c=. • •43 • .^.^^  •  o . .0. •• 0.^  0 •  CD.'Cy. CY.^:C=7.^0  cro: O0RP;9.•  •  0—  • . • • • • • . .^•^•^•^.  Figure 17 - Stratigraphic section measured through sediments exposed in Chilko River, just south of Highway 20 in Bull Canyon.  103  yellowish brown weathered surfaces and brown fresh surfaces. Occasionally the sandstone is finely bedded with individual beds 3 cm thick. Sandstone grades up to pale brown to yellow - brown weathering, friable, matrix supported conglomerate, initially with 0.5 to 1 cm diameter clasts, which then coarsen up to clasts 2 to 4 cm in diameter. Clasts are sub-angular to sub-rounded and composed of 80% chert (dominantly black and pale grey with lesser pink, red and purple) and 10% white quartz; the remaining 10% are granitic, sedimentary and volcanic clasts. Sandstone beds range from 0.28 to 6.2 m in thickness. Conglomerate beds are 1.1 to 1.5 m thick and sometimes lensoid thinning from 1.2 to 0.1 m thick. These sediments are lithologically similar to those described below in Churn Creek. Churn Creek  Good exposures of mid to Upper Cretaceous sediments can be found in Churn Creek where they are at least 1100 m thick (Fig. 18; Hunt and Bustin, 1990; Hickson et al., 1991, Mahoney et al., 1992). These sediments include chert pebble conglomerate, volcanic pebble to boulder conglomerate and sandstone with lesser siltstone and shale. Conglomerates are thin to very thick bedded and locally form fining upward channels that cut through the underlying finer grained sediments. The base of Cretaceous sediments in Churn Creek occurs in the core of an anticline, where amygdaloidal, highly fractured, brown to green andesite is overlain by basal Cretaceous sandstone and conglomerate (Hickson et al., 1991). Field evidence suggests the andesitic unit is late (?) Early Cretaceous in age (Hickson et al., 1991).  Sediments exposed in Churn Creek can be divided into 3 units based on clast composition: 1) a lower unit rich in chert detritus; 2) a middle unit dominated by volcanic detritus and 3) an upper unit dominated by volcanic and plutonic detritus  SECTION B  ^  SECTION A^  0 0  300 -1 ; 0  0 0 0 0  , o  0  0000 00o0 0. 0 0 0  ciVii  H  0000000•o  500 1..0  1  4:6; n2n  ; o : 0o  4; 010  Io  ,0 0.0 0.0 0.0 0'  ,  za 400 - o  .^ _ • 300  oTh •  6.6' Sb o3  0  l000eeo coo 000000000 . o o oo . 00000  oo o *coo oe • oeo 0000 200 -51 !. ° e0000000 = :  600 I  fc  II  nPA  SASS  II  ASS  A^&Aar] _y 4 A a 6. > c A A 4 AAA& AAAG.  A SP a a A A AAA A A A A AAAA A s a . A .  ,.. °g ,;77 ...:,. ^ .^-., ,.....c.00.° -.-  1001 7,-77;•  A Pa G A a 500 I  A A &AAA  0 00000000 0 0000000  - a •=•E• —.-5 o c 8.1 a -, -o  000000000 00000e00  0.  a  .o•o-ool  0 0000000 0 e  0  .00000  0  00000000 00000000  ,;°0:00;0 ,00°-  00000000 0 0 0 0 ^0 0 0  400 -1  '67  0  0 0 0 0 00000 . 0 . 0.0. 0. 0. 0 00 ..0  oo  o  10  300 H  foo 0 0 0 0 0 0  ! 10 e0 0 0 00,  1  0  0000  lio 000000ee  LEGEND 200-1 lo 0o^0 . 0 o  Laminated Siltstone  I°^0000  -j1 1 0°00 !° !..7-.° 5.7.7.7.=  771 Lithic Sandstone , A , A  A 4  o e o  Volcanic Breccia  779 c ,  0 0.0.^Conglomerate  loo-1 .•^  .  l0 0 . 0 0oc, 00 o .o o o . o o a o  '.>-<1^Covered Interval  so _!ao 000000 ioe 00 0 0 00 0 0,,,o co,,o  Channelized Conglomerate  lo 00000000 • ,0000000 . o.  --/\— Break in Section rr.  Lower K (?) Volcanic ROCKS  Figure 18 Composite stratigraphic section for sediments exposed in Churn Creek. -  Information from this study and Mahoney et al., 1992. Figure from Mahoney et al., 1992.  104  105  (Fig. 18 and Sections 31 to 36 in App. B). Each unit is characterized by rapid lateral and vertical facies changes. 1) lower unit The lower unit is at least 300 m thick and comprises thin to very thick bedded  chert pebble conglomerate, interbedded conglomerate and very coarse grained pebbly sandstone, and thin to very thick bedded, coarse to fine grained sandstone (Sections 31 to 34 App. B). Conglomerate and very coarse grained pebbly sandstone weather dark grey brown to pale grey, fresh surfaces are white to light grey with rusty blebs (Plate 21). Conglomerate is clast supported with angular to sub-rounded clasts 0.5 to 5 cm in diameter composed of varicoloured, dominantly pale grey, chert. The matrix is coarse to very coarse grained sandstone. Tabular conglomerate beds range in thickness from 0.35 to 2.5 m. These beds often fine upwards from pebbles at the base through pebbly sandstone to coarse grained sandstone at the top. Beds of pebbly sandstone are 20 to 50 cm thick and are separated by coarse grained sandstone beds 0.1 to 1.0 m thick. Conglomerate and pebbly sandstone beds locally form channels that scour into the underlying sandstone; however, contacts are usually gradational. Rare parallel laminae and trough cross-beds occur in the upper portions of some channels. In the pebbly sandstone beds sometimes the number of pebbles increases upwards and their size decreases. Coarse grained sandstone beds in the lower unit weather greenish grey, greybrown to rust-brown or rarely yellowish brown. Sparse pebbles ( < 2%) often occur within the sandstone beds oriented parallel to cross-bedding. Pebbles are usually chert and vary from less than 1 to a maximum of 2 cm in diameter. Locally, coarse grained sandstone grades up to finer grained sandstone in repetitive cycles 10 cm thick, or may be planar bedded with beds 5 cm thick. Coarse grained sandstone  106  Plate 21 - Chert pebble conglomerate of the lower unit of the Silverquick formation exposed in Churn Creek. Scale bar is 2 cm long.  107  beds between pebbly beds are often planar laminated (interlaminar spacing of 1.5 cm). Medium grained sandstone occurs in two forms: 1) thin bedded, dark brown weathering, pale greenish grey sandstone with sparse chert clasts less than 5 mm in diameter oriented parallel to bedding; and 2) lensoid, micaceous, carbonaceous, dark green-black to dark brown weathering dark green sandstone. The second form of medium grained sandstone is rare and occurs as discontinuous lenses that are usually flaggy and contain rip up clasts of siltstone up to 1.5 cm in diameter. Within this sandstone organic material occurs as 1 mm thick laminations spaced 3 mm apart. Locally these sandstone lenses are thinly bedded with beds 0.5 to 1 cm thick. Micaceous, carbonaceous, dark green-black fine grained sandstone also occurs as rare lensoid bodies. Sandstone in the lower unit (samples J89-236-08, J90-022-01, J90-021-01 App. C; Plate 22) is phyllarenite composed of: metamorphic rock fragments (1540% - dominantly metachert), quartz (20-25%), chert (10-30%), volcanic rock fragments (10-22%), sedimentary rock fragments (0-8%), plagioclase (0-10%), orthoclase (0-5%) and minor pyroxene, muscovite and biotite in a quartz-chlorite cement with minor carbonate cement, 0 - 25% matrix and 0.5 to 5% porosity. The lower unit passes gradationally to the middle unit through a transition zone 40 m thick where lithologies of the lower unit alternate with volcanic conglomerate and maroon sandstone beds of the middle unit. In this zone the number of volcanic clasts in the chert pebble conglomerate increases to a maximum of 30% until volcanic conglomerate becomes dominant in the middle unit. Within the transition zone pebble to cobble volcanic conglomerate weathers dark maroon, grey or brown and fresh surfaces are dark maroon to pale grey. This conglomerate is clast to matrix supported with sub-rounded clasts 0.4 to 20 cm in diameter, average 3 cm. Clasts are composed dominantly of feldspar phyric fine  108  Plate 22 - Sandstone from the lower unit of the Silverquick formation (upper photo). Photomicrograph of sandstone in the above photo (lower photo) - crossed nicols, magnification x 256.  109  grained dark grey volcanics and fine grained maroon, grey or dark brown volcanics. The matrix is fine to medium grained maroon sandstone. Outcrops of thick bedded, volcanic clast conglomerate are friable and range from 1.3 to 7.3 m thick. Maroon sandstone is coarse to fine grained and weathers dark grey maroon to dark brownish maroon, fresh surfaces are dark grey-maroon. This sandstone may be thinly bedded with beds 0.5 to 1.0 cm thick, is often cross-bedded and has rare fine grained grey clasts. Outcrops of maroon sandstone are friable and vary from 1.4 to 5 m thick. Maroon sandstone beds locally grade up to green, chert rich sandstone. Sandstones from the transition zone (samples J90-022-02, J90-023-05, J90023-10 App. C; Plate 23) are volcanic and phyllarenites. Volcanic arenites are composed of: volcanic rock fragments (80-92%), quartz (2%), chert (0- < 1%), sedimentary rock fragments (3-5%), plagioclase (2-10%) and pyroxene (1-3%) in a quartz or biotite cement with no matrix or porosity. Phyllarenites are similar to those of the lower unit and are composed of: metamorphic rock fragments (25%), quartz (40%), chert (6%), volcanic rock fragments (11%), plagioclase (10%), orthoclase (8%) and minor muscovite and rare pyroxene in a quartz cement. 2) middle unit  The middle unit is 500 to 600 m thick and dominated by volcanic pebble to boulder conglomerate with less massive volcanic breccia, sandstone and purple siltstone (Sections 35 and 36 App. B). Lateral facies changes are common but overall the middle unit generally fines upward from massive conglomerate at the base to interbedded siltstone and sandstone with conglomerate channels at the top (Plate 24).  110  Plate 23 - Sandstone from the transition zone between the lower and upper units of the Silverquick formation, exposed in Churn Creek (upper photo). Photomicrograph of sandstone in the upper unit , note increased feldspar content; crossed nicols, Magnification x 110.  111  Plate 24 - Channeled conglomerate of the middle unit (upper photo). Volcanic clast conglomerate of the middle unit (lower photo).  112  At the base of the middle unit (Section 35 App. B) the volcanic conglomerate is similar to that in the underlying transition zone. Clasts are angular to subrounded and vary in size from 0.6 to 70 cm in diameter, increasing in size upwards. At the base of section 33 clasts average 3 to 6 cm in diameter; towards the top clasts have an average diameter of 5 to 10 cm. Throughout section 35 the conglomerate beds grade up to coarse grained sandstone creating fining upward sequences 1 to 6 m thick. Sandstone at the top of the fining upward sequences may be thinly bedded or planar laminated with laminations spaced 1 cm apart, cross-bedding is rarely seen. Sometimes the laminations are defined by magnetic heavy minerals. Locally, fine grained sandstone lenses 30 cm thick by 1 m long occur within the conglomerate beds. Massive conglomerate beds vary from 1.1 to 6.5 m thick and rare interbedded sandy horizons average 0.6 m thick. The remainder of the middle unit is described in section 36 (App. B measured by Mahoney in Mahoney et al., 1992). Sections 35 and 36 are correlated via a massive volcanic breccia (100+ m), exposed at the top of section 35, that thins to the south and occurs as a 30+ m thick breccia in the lower part of section 36 (Fig. 18). The breccia, interpreted to be a lahar because of its chaotic nature, is unsorted, massive and composed of angular to sub-angular boulders of purple to green dacite in a dark grey fine grained matrix (Plate 25). In the middle and upper parts of the middle unit the conglomerate ranges from thick to very thick bedded, and is a crudely stratified, poorly sorted volcanic cobble to boulder conglomerate containing rounded to sub-angular andesite, dacite, flow-banded dacite and rhyolite, and rare granitoid clasts together with sub-rounded to rounded pebble sized chert clasts (Mahoney et al., 1992). The number of granitoid clasts increases upsection indicating a gradational contact between the middle and upper units. Conglomerate beds vary from tabular and laterally  113  Plate 25 - Lahar used to correlate sections in Churn Creek (upper photo). Purple siltstone slopes and interbedded resistant sandstone and conglomerate.  114  continuous to lenticular with well developed channels that grade laterally into thick to very thick bedded, coarse grained sandstone. Nested channels are locally evident. Fining and thinning upward sequences 15 to 20 m thick are common, and consist of thick to very thick bedded conglomerate that grades up to crudely laminated coarse grained sandstone with pebble stringers that in turn grades up into thin to thick bedded medium grained sandstone and minor siltstone. Lenticular, matrix supported volcanic clast conglomerate occurs locally, and consists of sub-angular to sub-rounded volcanic clasts in a dark grey, poorly sorted coarse siltstone to sandstone matrix. The volcanic clast conglomerate decreases in grain size, has a higher chert pebble content and a higher percentage of sandstone interbeds to the southwest. Medium to very coarse grained arkosic sandstone is interbedded with volcanic clast conglomerate and locally dominates the stratigraphy of the middle unit. Thin to thick bedded sandstone is tabular and laterally continuous and displays erosive basal contacts, weak parallel and cross laminae, graded bedding and pebble stringers. Pebble to cobble conglomerate channels are locally present and pebble stringers define trough cross-beds in some areas. The sandstone displays both fining and thinning upward and coarsening and thickening upward sequences. In some places sandstone beds (5-20 m thick) are repetitively interbedded with conglomerate beds (0.5 to 5 m thick). Locally sandstone-conglomerate sequences grade up into 1 to 20 m thick purple siltstone intervals (Plate 25). Purple siltstone is parallel laminated, fine to coarse grained, and contains fine pebbles in part. The siltstone weathers recessively and forms reddish-purple slopes between resistant sandstone and conglomerate interbeds. Moderately well developed channels (1-10 m wide) of coarse grained sandstone and conglomerate are interspersed within thick siltstone intervals. Purple  115  siltstone dominated intervals grade laterally into sandstone and conglomerate over distances of less than 150 m. 3) upper unit The upper unit is at least 165 m thick and conformably overlies the middle unit. Pink quartz monzonite clasts, characteristic of the upper unit, are found below the contact between the upper and middle units suggesting that this contact is transitional. Locally the contact is abrupt and is marked by a fairly rapid transition from purple siltstone and lenticular sandstone to thick to very thick bedded volcanic and plutonic clast conglomerate. The upper contact of the Cretaceous sediments in this area is not exposed. The upper unit is dominated by clast supported volcanic cobble to boulder conglomerate with sub-angular to sub-rounded clasts of andesite, dacite, varicoloured chert and up to 30% pink quartz monzonite (Plate 26). Volcanic clasts are pebble to boulder size, chert clasts are pebble sized and quartz monzonite occurs as cobble to boulder sized clasts. Distinctive pink quartz monzonite clasts increase in size both upsection and laterally to the south. Conglomerate is highly lenticular and contains abundant channels 3 to 5 m thick and 15 to 20 m wide that aggregate into roughly tabular, laterally continuous successions. The channels have sharp, erosive bases, contain clast supported boulder conglomerate at the base and grade up into matrix supported conglomerate and crudely laminated and crossbedded, coarse grained sandstone with abundant pebble stringers. Parallel laminated, thin to thick bedded, fine to medium grained sandstone and reddish brown coarse siltstone locally cap channelized intervals. Parallel laminated, fine grained sandstone and coarse siltstone locally aggregate to 2 to 10 m thick sequences. Lenticular matrix supported conglomerate, with a matrix of coarse grained sandstone, is common within this unit.  116  Plate 26 - Granitic clast conglomerate of the upper unit, exposed in Churn Creek.  117  AGE, DEPOSITIONAL ENVIRONMENT AND PROVENANCE Age A siltstone, collected during the 1990 field season, from within the lower unit of the sediments exposed in Churn Creek yielded a Late Albian-Early Cenomanian palynomorph assemblage including: Dinocysts Fern spores -  Pseudoceratium expolitum Aptea cf. rugulosum cf. Carpodinium obliquocostatum Distaltriangulisporites irregularis Cyathidites minor Concavisporites sp.  Gymnosperm pollen -  Eucommiidites troedssonii Vitreisporites pallidus  Angiosperm pollen -  Tricolpites crassimurus Tricolpites micromunun Tricolpites minimus  Depositional Environment and Provenance  The thickness and sedimentary structures of Cretaceous sedimentary strata exposed along Churn Creek record fluvial deposition in a rapidly subsiding depocentre. Poorly defined parallel and cross-stratification, common normal grading, poor sorting, rapid lateral facies changes, pebble lag deposits and the presence of overlapping channels indicate deposition in a braided fluvial system (Rust, 1972, 1984). Sedimentary structures that provide information on paleo flow directions are sparse in Cretaceous sediments of the southern Chilcotin-Nechako region and those mentioned below may not be representative of a whole unit. The lower unit is dominated by chert rich sandstone and conglomerate. Cross-beds from a 2 m thick interval in the upper part of this unit indicate a southsouthwest directed paleocurrent (Fig. 19). The Cache Creek terrane exposed to the  118  Figure 19 - Paleocurrent data for sediments in the lower unit exposed in Churn  Creek. a) Stereoplot of the poles to cross-bedding, b) stereoplot of rotated poles to cross-bedding and c) rose diagram based on the data in b, giving a plot of trends of paleocurrent directions. Flow is from the northeast.  119  northeast represents the probable source terrane for chert in this portion of the section. Based on lithologic and paleontologic evidence Garver (1989) suggests the Bridge River terrane, which forms the eastern margin of the Silverquick Conglomerate to the south in Tyaughton Basin, is the primary source of chert detritus in that area. The transition from chert to volcanic dominated lithofacies at the boundary of the lower and middle units marks a change in source area and basin dynamics. Well sorted, well bedded sandstone and pebble conglomerate of the lower unit are overlain by thick to very thick bedded volcanic cobble to boulder conglomerate and poorly sorted coarse grained sandstone of the middle unit. The increase in grain size, decrease in sorting and the lack of stratification evident in the middle unit suggests rapid deposition proximal to a volcanic source. The presence of 100+ m thick lahar supports the interpretation of proximal volcanic activity. The contact of the lower and middle units may record the onset of volcanism in adjacent areas. This influx of volcanic material apparently flooded the depocentre overwhelming northeasterly derived chert rich sediments. Sedimentary structures that provide paleoflow data are also scarce in the middle unit, those that are present suggest a flow from the south-southwest. The Upper Albian to uppermost Albian Spences Bridge Group (Thorkelson and Rouse, 1989) exposed to the east and south is a probable source for volcanic detritus of the middle unit. Cretaceous volcanics exposed to the north (Hickson, 1992) are another possible source for volcanic detritus. The marked increase in clast size and the amount of plutonic debris at the contact of the middle and upper units suggests changing basin margin tectonism. The upper unit coarsens upward and contains a significant proportion of boulder sized, angular pink quartz monzonite clasts that increase in size and abundance upsection and to the south. The abundance of coarse grained detritus, angular  120  plutonic boulders that increase in size and abundance both vertically and laterally, and the lack of well developed fluvial features suggest the upper unit may represent an alluvial fan facies adjacent to a proximal highland (Rust and Koster, 1984). DISCUSSION  Cretaceous sediments exposed in northern Chilcotin-Nechako region are part of the Skeena Group as defined by Tipper (1976). This definition includes the Red Rose and Brian Bora Formations defined by Sutherland Brown (1960; Fig. 20). Sediments of the Red Rose/unnamed sediments (Fig. 10; herein referred to as the Red Rose division) are underlain by the Rocky Ridge volcanics and the Kitsun Creek sediments in the Smithers area (Tipper, 1976). The Rocky Ridge Volcanics are a localized unit that outcrops only on Rocky Ridge where they are conformably overlain by Red Rose division sediments to the north and underlain by Kitsun Creek sediments to the south in Kitsun Creek. In Whitesail map area (93E) Maclntyre (1985) documents amygdaloidal basalt flows lying conformably beneath Skeena Group sediments (Rocky Ridge volcanics equivalents ?). At one locality Maclntyre (1985) documents a relatively flat lying conglomerate which appears to conformably underlie amygdaloidal basalt flows; he suggests this may be the basal member of the Skeena Group in Whitesail map area. In Smithers map area (93L) basal Kitsun Creek sediments of the Skeena Group are described by Tipper (1976) as coarse to fine polymict conglomerate, greywacke, dark grey shale and coal with minor rusty red tuff related to the Rocky Ridge volcanics and are believed to be Hauterivian to (?) Albian in age. During this study no exposures were found that could be positively identified as Kitsun Creek sediments, although sediments exposed in Gramophone and Reiseter Creeks have been mapped as part of this unit by Tipper (1976). Sample  121  Brian Bow Formation  - Varicoloured porphyritic andesite flows & breccias tuff & volcanic sandstone  1300 - 1800 m Conformable contact (?) Member D  - Conglomerate, greywacke, shale & hornfelsic equivalents  15 - 150 m Interfingering content  c o  Ts  Member C 300 - 360 m  E  Conformable contact (?)  8 0  m o cr a Cr -  - Interbedded greywacke, siltstone & shale & homfelsic equivalents.  Member B  - Shale, siltstone & homfels  1200 m Conformable contact Member A 750+ m  - Interbedded shale, siltstone, & greywacke with some pebble conglomerate and coal plus hornfelsic equivalents  Figure 20 - Red Rose and Brian Boru Formation defined by Sutherland Brown, 1960.  122  J90-041-01a (Appendix B) is from the Kitsun Creek area. J90-FT#4 (Appendix B) is a sample from an outcrop identified as Kitsun Creek sediments by T.A. Richards (Pers. Comm., 1990). Sample J90-041-la has a similar composition to J90-FT#4 and is probably Kitsun Creek sandstone (Table 3). Samples from Gramophone Creek (J89-249 and J89-249-01, Table 3 and Appendix B) have similar compositions to those of the Kitsun Creek sediments and the Red Rose division and it is not possible to assign them a position within the Skeena Group based on lithology. Jurassic sediments of the Bowser Lake Group and some sediments within the Hazelton Group have similar lithologies to those of the Skeena Group and often cannot be distinguished unless the age is known. Paleocene sediments similar to those of the Skeena Group, but less well lithified, are exposed in Gosnell Creek (Gosnell Creek section, Appendix B; sample J90-040-01b in Appendix D; Plate 27). Similarities in age, lithology, stratigraphy and depositional environment suggest Cretaceous sediments exposed in Churn Creek, in the southern ChilcotinNechako region, are correlative with the Silverquick formation of the Battlement Ridge group exposed to the south in Tyaughton Basin. The Silverquick conglomerate (Fig. 21) is a 1500+ m thick sequence of Late Albian to Cenomanian chert pebble and volcanic clast conglomerate typified by rapid and dramatic changes in thickness and sedimentary characteristics (Garver et al., 1989). Both the Silverquick formation and the sediments exposed in Churn Creek are of Late Albian - Early Cenomanian age. The depositional environment of both sedimentary sequences is similar. The sediments exposed in Churn Creek were deposited in a braided fluvial system; a braided fluvial to submarine fan environment of deposition has been proposed for the Silverquick formation (Glover et al., 1988). Like the sediments exposed in Churn Creek the Silverquick formation can be divided into basal chert rich sediments and gradationally overlying volcanic rich sediments (Garver et al., 1989). The lower member of the Silverquick conglomerate  123  Plate 27 - Paleocene sediments exposed in Gosnell Creek.  ▪  124  BATTLEMENT RIDGE GROUP c 0 fes E C5 a) 2 0 a) O EL c O fii E 8 _. E 0 = O ET o a) ir)  1  — >  0 0 D  cr)  0  •111110M,  - Volcanic breccia and lapilli tuff of andesitic to basaltic composition, intercalated with fine grained tuff, basaltic to andesitic flows and epiclastic sediments. These volcanics can locally be subdivided into a lower massive unit and an upper bedded unit dominated by andesitic lahars and epiclastic sediments.  0  0  >  - Volcanic clast conglomerate. Clasts are cobble to boulder size. Interbedded with this conglomerate are chert rich conglomerates typical of the lower member and andesitic breccias.  - Poorly stratified, clast supported and locally horizontally and cross-bedded pebble conglomerate with minor sandstone interbeds. Sandstone weathers maroon and finer grained intervals contain stick and leaf fossils. Conglomerate is dominated by chert (50%) clasts with lesser sedimentary (20-25%) and volcanic (20%) clasts and minor amounts of metamorphic (5%) and plutonic (<5%) clasts. Consists of numerous fining upward sequences 2 to 8 m thick of pebble to cobble conglomerate and minor fine grained intervals.  Figure 21 - General stratigraphy of the Battlement Ridge group.  125  comprises chert pebble conglomerate with minor ( <10%) sandstone interbeds (Glover et al., 1988). This is lithologically very similar to the lower unit exposed in Churn Creek (Fig. 18). The only notable difference is in the thickness. The lower member of the Silverquick formation has a maximum thickness of 1500 m whereas the thickest section of the lower unit exposed in Churn Creek is 300 m thick. However, the base of the lower unit in Churn Creek is rarely exposed and this unit may be much thicker than is presently known. The basal chert pebble conglomerate of the Silverquick formation is gradationally overlain by volcanic cobble to boulder conglomerate (Fig. 21; Garver et al., 1989; Glover et al., 1988). This sequence also occurs in Churn Creek where  the volcanic clast conglomerate of the middle unit gradationally overlies the chert pebble conglomerate of the lower unit. In Churn Creek the middle unit is gradationally overlain by the upper unit which is distinguished by the presence of a significant proportion of plutonic clasts. These plutonic clasts were derived locally from a fault scarp and are not laterally continuous (Mahoney et al., 1992). Thus it is not surprising that the upper unit exposed in Churn Creek has no correlative to the Silverquick formation. The upper member of the Silverquick formation grades into the overlying Powell Creek Formation which is comprised of volcanic breccia and lapilli tuff of andesitic to basaltic composition, intercalated with fine grained tuff, basaltic to andesitic flows and epiclastic sediments. A similar transition occurs in Churn Creek where sediments of the upper unit grade up into lahars and volcanic breccia. Cretaceous sediments exposed in the Mount Tatlow - Taseko River area are lithological (and age ?) equivalents to those of the Battlement Ridge group but, are mapped as part of the Kingsvale Group. However, the Kingsvale Group in western Taseko Lakes map area (920) is dissimilar to that in the type area near the village of Kingsvale and thus, the use of the term Kingsvale Group should be abandoned.  126  Sedimentary and volcanic rocks mapped as Kingsvale Group in western Takeko Lakes map area should be included in the Battlement Ridge group The Kingsvale Group in the Mount Tatlow - Taseko River area has been described by Jeletzky and Tipper (1968) and McLaren (1990) and is composed of over 4500 m of non-marine latest Albian to Cenomanian or later (?) sediments and volcanics (Fig. 22). Jeletzky and Tipper (1968) subdivided the Kingsvale Group into four units, which they named divisions A, B, C, and D. Tipper (1978) later divided the Kingsvale Group into a lower sedimentary unit, equivalent to Jeletzky and Tipper's (1968) division A, and an upper volcanic unit correlative to Jeletzky and Tipper's (1968) units B, C and D. This mapping convention was followed by McLaren (1990) in the Chilko - Taseko Lakes area. The lower sedimentary unit/division A is equivalent to the lower unit exposed in Churn Creek and to the lower chert rich member of the Silverquick Formation of the Battlement Ridge group, defined for the southeastern portion of Taseko Lakes map area by Glover et al. (1988) and Garver (1989). The upper volcanic unit (divisions B, C and D) is equivalent to the volcanic clast rich middle and upper members and the overlying lahars exposed in Churn Creek and to the upper member of the Silverquick conglomerate and the overlying Powell Creek Volcanics. F. REGIONAL CORRELATIONS  Cretaceous sediments exposed in northern, central and southern ChilcotinNechako region have similarites in age and lithology making regional correlations between the different areas possible (Figs. 23 and 24). Throughout the region Albian-Cenomanian chert rich sediments are capped by younger volcanics. Only in the south do the chert rich sediments grade up into volcanic rich sediments (middle and upper units of the Silverquick Formation). The depositional environments vary  127  KINGSVALE GROUP  O  O  (.1 0  C  O  >  a)  0  O  0  C  CCS  E  E O  O  O  O  • ImMIM  O  • 111■1  O C  co  O I.  as  E  C  O  'ET)  O cc)  - Interbedded coarse volcanic breccias and tuffs, same as Division B.  0  O  >  0  I.  C)  O  C.)^C/) C C RS CD  O E "T) '8 a) (/)  - Mainly conglomerate, greywacke and shale and interbedded tuffs, breccias, and tuffaceous sediments. Conglomerates have mainly volcanic pebbles and cobbles up to 20 cm in diameter and in places boulders up to 30 cm. - Interbedded coarse volcanic breccias and tuffs. Breccias with angular fragments up to 60 cm in diameter are present in beds up to 45 m thick. Breccias are poorly sorted and typically andesitic and basaltic. Colours are typically maroon, purple, bright green, mauve grey, dark grey & brown. Breccias have a fine tuffaceous matrix. Interbedded tuffs are fine grained and occur in thin layers 3 to 30 cm thick. Tuffs are more abundant near the base of the division where they grade into the underlying sediments of Division A.  C13 E O O  CD 0  C  O  :C7)  >  0  - Interbedded greywacke, conglomerate and shale. The sediments are very micaceous and in places poorly consolidated. The conglomerates contain mainly chert pebbles as well as abundant volcanic pebbles and granitic debris. Beds are generally 3 to 5 m thick. Wood fragments and plant remains are common. Non-marine.  Figure 22 - General stratigraphic section for the Kingsvale Group.  128  Figure 23 - Regional correlation of Cretaceous stratigraphy within the ChilkotinNechako Region.  ▪  Terrestyki  Depth (m)  ii= Ne:s ureshor strd troe i i Eccene (!) to mid Eocene 1000  0  500  C  0 C  0  Romaine Corse WICaliC amid ant tuffs  to U)  3  2003  L 0 0  C  Cr  1500  C  0  0  V)  0  0^4000 0  4500  C 3  L  U)  5X0  5500  6000  Cheri pa% ccnilimhefflte, stale cod gist= Vdemics, ss3k aid sitstam, late Ecrly to kabedded stock midde Aloim C aid chat pebble andomerate 0 C 91de and sitstone with accretion min( alert pebble condaoerate Antics' Conglomerate  Nonmarim Chert Pebble Condomerate  1Icricdotred  ^PhrPhrlic andesitic to Prim^ drainbreccia, Baru Famation flows and tuft  Corocnin leolger  Hornblende-fddspa and homblenckKaska biotite-teldspa Cmup porphyry  Cenomanal to Santcoin  (1)  c 4)  0  0 J  _C 0  co rldesilic ib4loicr^ Unantormo5le to catkonctie =tit ▪  -  0  E  LC N  Ifeaceors, kile Saufstme (9Tuarbildes) le  o L (I)  5CCO  4)  0  ^(11  greweacke ad shale  0  midie to Late PJbim  L  hiP litn talerlbdedded C*Intrate crIstd H  C  sitstgmrermcke' e aid stole  IOW  confonnotk antoc1  E  00 Oa 0  Pebbleartrate Cond  late [My to Late elm  1503  :colandle contact 5500 VC V0  DM 0 0  E 0 0 u_  80% gale and Interbedded Saddam 20Z 1kIcak Pebble Conglomerate  ■  a  B  2500  Shoe  • ['halm  sitstone  to Ealy Cenommim  3 0  0  C  A Ecrly Abe or older  E: °.  Cheri  C  C  •  11$ ••  _Y 0  Late Aim to Gammen  3 t.  NarnaMe Interbedded aerode, cherl and mimic pebble conglomerate shde, Wane, tuffs and toffocecos mina *iconic breeds C 0 and flows. The mount of > condamrate Maeoses 0 upseclon.  2500  0 36/3)  3000  4)  0  Grolotional Cattat  t.  Z  3 0 (./)  Crodaticed contact  0  Coarse mIcmic  To tuffs.  0 2°°I) 01  J  0  _c  .  a°  a3  0 aeccia aid  0 >  C  E  ." C  0 0  1500  0L  C  C  2500  eddy Late Cretaceous  fformaine  (5  0  = ^  CL  3 0  thael^Cam:Krim  Volanic breads ad tows  o o  Woconichtim  _  Nonmaine Dnisim Volcano dast *mote, go ron and shde, interbedded tuffs, keccias and tuffo:eous safments  1500  Island Ti  !termite  /- \^1000  to  mene to arty Oligocem late Eccene  500  0  Depth (m) 0_  1261  DCPC9110NAL^AGE ENVIMNIOT Tern:said^Eat/ Wotan  Depth (m) 0  Nor ton -1 -1 late mdde kat  licrne  Terrestrd 1 *Oat  Cadre Creek (?)  4500  kfferbeided stole sitstone awl mitorcrie coorner procie Pak and cod.  •  Rocky Fkge  Iblcmi3  Wenn (?) to Abin (?) rrt.sun Payne condornerate, Hauteriwin to Creek greyrate. tick oat _ (?) Nbice moor rusty red tuff related to be Rocky Ridge 101alliCS -  130  Kingsvale Group sediments Powell Creek volcanics Kasalka Group w.Aw O w MO.  Kingsvale Group sediments  ^ Silverquick conglomerate Red Rose division sediments  r+  Spences Bridge Group  E  Rocky Ridge volcanics Kitsun Creek sediments  tE Taylor Creek Group Relay Mountain Group Shale  : :1 Bowser Lake Group Hiatus  M Jackass Mountain Group  Figure 24 - Regional correlation block diagram, based on figure 23.  131  Northern Chilcotin-N echako Region "Pk ..MOVATATO  "WWWW/n  Central ChilcotinNechako Region  ,,•■•■•■•■•■VAIIA, ,,AVAWAVAVAVAV., ■■■■■■■■■■■■■■■■  AW^IWOIMe -(AMVA70000  .eAVATegeinNIM,  ,AAWAY 0 A^AAAAAAAAAAAA• ..foogirAva^er  ..:031020"  ■IAWANWAWAYV :40AWAYAWAXAT AWAYWWWWW AAAAAAAAAAAA  ■tOgegar vpure  95 105 115 125 135 145  Santonian Turoman  155  Cenomanian^95  165  105 — 95  Albian Aptian Barremian  115  — 105  125  — 115  Hauterivian Valanginian^135  —  Berriasian 145  135  Tithonian Kimmerid ian  125  155  — 145  Oxfordian  — 155  Southern Chilcotin-Nechako Region  ^7— 165  132  from area to area• marine conditions persisted into the Cenomanian in the north and the Maastrichtian in the centre, but ceased in mid-Albian time in the southern Chilcotin-Nechako region. In northern Chilcotin-Nechako region, Hauterivian (Tipper, 1976) to Cenomanian sediments of the Skeena Group are separated from the underlying Bajocian - Kimmeridgian/Tithonian Bowser Lake Group (Cookenboo and Bustin, 1989) by a major hiatus (Tipper and Richards, 1976). The basal Hauterivian - (?) Albian Kitsun Creek sediments of the Skeena Group are fluvial in origin (Tipper and Richards, 1976). Marine sedimentation began in Early to mid Albian time with the deposition of the basal Red Rose division (Duffel, 1959; Tipper and Richards, 1976) and continued at least until the Cenomanian. In southern Chilcotin-Nechako region there is a shorter Early Cretaceous hiatus than in northern Chilcotin-Nechako region. Marine sediments of the Late Oxfordian - Barremian (Jeletzky and Tipper, 1968; Tipper, 1978) Relay Mountain Group are overlain by Lower Albian( or older ) - upper Lower to middle Albian (Jeletzky and Tipper, 1968; Garver, 1989) sediments of the Taylor Creek Group. The marine Taylor Creek Group is overlain by the fluvial Upper Albian Cenomanian Silverquick formation (Garver, 1989; Glover et al, 1988) and equivalent rocks of the Kingsvale Group (Jeletzky and Tipper, 1968; McLaren, 1990). Sediments of the Taylor Creek Group and Silverquick formation have similar ages and lithologies to the Red Rose division of the Skeena Group. These sediments may be depositional equivalents deposited at opposite ends of a mid to Late Cretaceous basin (Fig. 24). Similarities between Cretacous sediments exposed in northern ChilcotinNechako region and those exposed to the south were also noted by Duffell (1959) and Jeletzky and Tipper (1968). They point out that the middle Albian sediments  133  (Red Rose division of the Skeena Group) and overlying volcanic rocks (Kasalka Group) exposed in the Whitesail map area (93E) in northern Chilcotin-Nechako region are similar to divisions A and B of the Kingsvale Group in southern British Columbia, with one notable difference - the sedimentary rocks at the base of the Kingsvale are continental in origin. In central Chilcotin-Nechako region the oldest known Cretaceous sediments occur about 3 km below the surface, at the base of the Nazko D-96-E well (Fig. 12). These sediments are terrestrial in origin and have an Aptian age. They sit unconformably (?) on interbedded chert, limestone and igneous rock which may be equivalent to the Cache Creek Group. Overlying the Aptian sediments are upper middle Albian strata deposited in a nearshore marine environment (Fig. 12). These sediments may be equivalent to sediments of the marine Taylor Creek Group and the Red Rose division of the Skeena Group (Fig. 24) as they have similar lithologies and ages. Upper middle Albian sediments in the Nazko well are overlain by upper Albian to Cenomanian sediments about 2500 m thick (Fig. 12). These sediments include sandstone, shale and chert pebble conglomerate and may be equivalent to the Silverquick formation and the upper part of the Red Rose division (Fig. 24). Like the sediments of the Red Rose division sediments in the Nazko well were deposited in a dominantly nearshore to transitional marine environments (Table 5). Cretaceous sediments in northern Chilcotin-Nechako region are overlain by Albian (105 Ma; Maclntyre, 1985) or Cenomanian (93 Ma; Rusmore et al, 1991) to Santonian (87 Ma; Maclntyre, 1985) volcanics of the Kasalka Group or Santonian (84 Ma) to Maastrichian (70 Ma) (Woodsworth, et al., 1983) volcanics of the Brian Boru Formation. In southern Chilcotin-Nechako region mid Cretaceous sediments are partially correlative with volcanics of the Upper - uppermost Albian (Thorkelson and Rouse, 1989) Spences Bridge Group and are overlain by (?)  134  Cenomanian - (?) Santonian (Garver, 1989) volcanics of the Powell Creek formation. In central Chilcotin-Nechako region volcanics of Cenomanian (or younger ?) to Santonian age occur about 2.3 km below the surface at the base of the Chilcotin B-22-K well (Fig. 12). The volcanics are about 1400 m thick and include feldspar phyric, augite (?) phyric and fragmental units (Section Appendix B). These volcanics may be correlative with the Powell Creek formation and the Kasalka Group (Fig. 24). Overlying the volcanic rocks in the Chilcotin well are 1700 m of Santonian (and older ?) to Maastrichtian, nearshore to transitional marine, interbedded sandstone and shale composed dominantly of volcanic detritus. Sediments of this age are not known from elsewhere within the Chilcotin-Nechako region. However, McKenzie (1985) mapped sediments of a similar age north of the ChilcotinNechako region in the Sustut basin.  G. BASIN FORMATION Mid to Late Cretaceous sediments within the Chilcotin-Nechako region lie within the Intermontane belt of British Columbia on the western edge of Stikinia, and include the Tyaughton Basin. These sediments are largely separated from older sediments by a major hiatus (Fig. 24). Sediments stratigraphically beneath the mid to Late Cretaceous sediments of the Chilcotin-Nechako region were deposited in the Nechako Basin (Tipper and Richards, 1976; Tipper, 1984) which formed when the Hazelton trough was divided in two by the Bajocian uplift of the Skeena Arch (Figure 3c in Tipper and Richards, 1976). The Tyaughton Basin formed along the Yalakom fault early in the Late Jurassic (Tipper, 1984). Following the major hiatus an Albian sea spread over much of central and southern British Columbia (Figure  135  14 in Tipper, 1984) and the deposition of mid to Late Cretaceous sediments within the Chilcotin-Nechako region began. Cretaceous sedimentary rocks within the Chilcotin-Nechako region are poorly exposed and there is insufficient data to determine if the sediments formed in one large basin or in a number of smaller, isolated, basins separated by areas of differential uplift. Tipper (1984) suggested that in Early Cretaceous time many of the uplifted areas controlling sedimentation collapsed allowing an Albian sea to spread over much of central and southern British Columbia. Based on correlations, it appears likely that mid to Late Cretaceous sediments within the ChilcotinNechako region were deposited in one large basin, herein referred to as the Nazko Basin, outlined by this Albian transgression. Sedimentation continued within the Nazko Basin until the Cenomanian when volcanism became dominant throughout the Chilcotin-Nechako region. Later (and syndepositional ?) tectonic activity (compressional ?) probably affected the distribution of sediments within the Nazko Basin and the areal extent of the sea which is known to have persisted at least until the Cenomanian in northern Chilcotin-Nechako region and until Maastrichtian time in central Chilcotin-Nechako region. North of the Chilcotin-Nechako region correlative sediments in the Bowser Basin were also deposited in a marine environment (Cookenboo, 1989) suggesting that the Nazko Basin may extend beyond the northern margin of the Chilcotin-Nechako region. Sediments of the Nazko Basin provide insights into the tectonic development of southern and central British Columbia. In particular they provide information pertaining to the suturing of the Intermontane and Insular superterranes (Fig. 3). There is increasing evidence to suggest that the Intermontane and Insular superterranes (of Monger et al., 1982) of the Canadian Cordillera were in close proximity, if not actually joined, by mid Jurassic time. Using stratigraphic similarities Tipper (1984) concluded that the superterranes were juxtaposed by  136  Callovian time. Van der Heyden (1989) described similar Jurassic plutons on both inboard and outboard terranes. Armstrong (1988) states that the superterrane linkage was accomplished prior to 130 Ma. More recently, Gehrels and Greig (1991) have reported U-Pb data from detrital zircons of the Gravina belt that show the Alexander-Wrangellia terrane was in sedimentary proximity to the Stikine and Yukon-Tanana terranes during the Late Jurassic. Other researchers have concluded that collision occurred in the middle Cretaceous after the closure of a large ocean basin (Monger, et al., 1982; Crawford et al., 1987; Thorkelson and Smith, 1989). Aptian (?) to mid Albian Taylor Creek Group and Late Albian to Cenomanian Kingsvale Group sediments of the Nazko Basin contain clasts derived from a westerly source located on the Insular Terrane (Jeletzky and Tipper, 1968; Garver, 1989; McLaren 1990), clearly indicating that Terranes I and II were amalgamated by Late Aptian -Early Albian time. It is possible that the mid Cretaceous event represents the final amalgamation of the Intermontane and Insular superterranes, but it is unlikely that the closure of a large ocean occurred at this time. BASIN INFILLING  Basal sediments of the Taylor Creek and Jackass Mountain Groups are the oldest sediments within the Nazko Basin. They were deposited when Aptian uplift in southern Chilcotin-Nechako region led to a narrowing of the Tyaughton Basin; much of the southwest flank, previously covered by Late Jurassic and Early Cretaceous seas, was elevated above sea level and underwent rapid erosion (Jeletzky and Tipper, 1968). Clast compostion of basal conglomerate of the Taylor Creek Group indicates derivation from a southerly uplifted source. Coarse grained basal sediments of the Aptian to (?) mid Albian Jackass Mountain Group, deposited  137  on the northeast side of Tyaughton Basin, suggest uplift of the northeast side of the basin during the Aptian (Jeletzky and Tipper, 1968). Widespread inundation of central and southern parts of western British Columbia by marine waters occurred in late Lower Albian time. Sediments of the Taylor Creek and Jackass Mountain Groups continued to be deposited in the Tyaughton Basin, but also overstepped the margins of this basin (Tipper, 1969) thus marking the beginning of deposition in the Nazko Basin. In southern Nazko Basin basal conglomerates of the Taylor Creek and Jackass Mountain Groups were succeeded by thick deposits of greywacke, siltstone and shale reflecting the slowing of uplift in the source areas (Jeletzky and Tipper, 1968). Marine sediments of the Taylor Creek Group overlapped the nonmarine Jackass Mountain Group in mid Albian time. Taylor Creek Group sediments were derived from a volanic source to the west on the Insular terrane and a chert rich source to the east, probably uplifted rocks of the Bridge River complex (Garver, 1989). Jackass Mountain Group sediments were deposited only on the northeast side of the basin and had a source to the north or northeast (Jeletzky and Tipper, 1968). During the time of deposition of the Taylor Creek and Jackass Mountain groups in southern Nazko Basin marine sediments were also being deposited in central and northern Nazko Basin: Lower Albian to Cenomanian Red Rose division sediments were deposited in northern Nazko Basin and unnamed sediments in central Nazko Basin (Nazko D-96-E well; Fig. 25a). These sediments are dominantly composed of chert, most probably derived from the uplifted Cache Creek terrane to the east, and lesser metamorphic detritus eroded from the Omineca Belt also exposed to the east (Tipper and Richards, 1976). Both Cache Creek and Omineca Belt rocks were uplifted in Late Jurassic to Early Cretaceous time (Parrish, 1979; Cordey et al., 1987). The discovery of Early to Middle Jurassic  138  Figure 25 - Nazko basin paleogeography  a) Early Albian - deposition of the marine Taylor Creek Group and non marine Jackass Mountain Group in southern Nazko Basin; deposition of marine to marginal marine sediments of the Red Rose division of the Skeena Group in northern Nazko Basin; and deposition of marine unnamed sediments in central Nazko Basin; b) Late Albian - deposition of non marine Silverquick formation and lower Kingsvale Group in southern Nazko Basin; continued deposition of marine and marginal marine sediments of the Red Rose division in northern Nazko Basin; continued deposition of unnamed marine sediments in central Nazko Basin; c) Latest Albian to Early Cenomanian transition to a volcanic province - deposition of the Spences Bridge Group, Powell Creek formation and Kingsvale Group volcanics in southern Nazko Basin; deposition of the Kasalka Group in northern Nazko Basin; and deposition of unnamed volcanics in central Nazko Basin, some or all of which are sub marine; d) Santonian - continued volcanic deposition in the southern Nazko Basin (Powell Creek formation); continued deposition of volcanics in northern Nazko Basin (Kasalka Group and Brian Boni Formation); renewed deposition of unnamed marine sediments in central Nazko Basin. S = Smithers N = Nazko CC = Cache Creek Terrane OB = Omineca Belt RRD = Red Rose Division of the Skeena Group TCG = Taylor Creek Group JMG = Jackass Mountain Group KVG = Kingsvale Group  139 CC  OB /\\ /\ Ba/ a.1 RRD  CC OB A  4— (?) Unnamed Seds /\ /\^/\  RD\ (?) Unnamed Seds  •  "z\ /\  /\  .^/\ . Silverquick ower KVG \ ^fr.\^/\ t6  \^\ \  TCG740•I 4- JMG V11/4^\  \  INTERMONTANE TERRANE Tyaughton^Methow Basin Basin^Bridge River Terrane  a) Early Albian  ^  CC^OB  •sA  17a.salka Group Unnamed volcanics  /  KVG volcan cs  /Spences Bridge Group, Unname volcanics owell Creek formation  S  Direction of sediment transport Tyaughton^Methow Basin Basin^Bridge River Terrane  b) Late Albian CC^OB z\^/\ s^/\ /\ • A-\ z A ^Kasalka Group /\^Brian Boru N/' /korniation (?) ^".Unnamed Seds ,,Powell Creek formation  A  . \/\ „-  INTERMONTANE TERRANE Tyaughton^Methow Basin Basin^Bridge River Terrane  c) Latest Albian to Cenomanian  Marine Conditions  Tyaughton Basin  Methow Basin Bridge River Terrane  d) Santonian  ,  140  fossils in the Cache Creek terrane (Cordey et al., 1987) suggest it may be, in part, equivalent to the Bridge River terrane in southern British Columbia that provided detritus to the Taylor Creek Group and Silverquick formation in southern Nazko Basin. Marine deposition continued into Late Cretaceous time in all but the southern portion of the Nazko Basin. In northern Nazko Basin marine and marginal marine deposition of the Red Rose division continued until Cenomanian time, as evidenced by sediments exposed in Houston Tommy and Denys Creeks. Marine deposition of of unnamed sediments continued in central Nazko Basin also until the Cenomanian (Nazko D-96-E well). However, in southern Nazko Basin deposition of the marine Taylor Creek Group ceased in the mid Albian when it was replaced by fluvial deposits of the Silverquick formation (as exposed in Churn Creek and south of the Yalakom Fault in Tyaughton Basin; Garver, 1989) and basal Kingsvale Group (Taseko River area; Fig. 25b; Jeletzky and Tipper, 1968; McLaren, 1990). The composition of the lower unit of the Silverquick formation is dominated by chert detritus eroded from the Bridge River Complex exposed to the east (Garver, 1989). Rocks of the Kingsvale Group were deposited on the southwest side of Tyaughton Basin from Late Albian to Cenomanian time (Jeletzky and Tipper, 1968). Basal sediments have a westerly source (Mclaren, 1990) indicating renewed uplift of the southwest flank of Nazko Basin in the latest Early Cretaceous. Latest Albian to Cenomanian time marks a transition in the Nazko Basin from a dominantly sedimentary to a volcanic province. During the Cenomanian marine conditions ceased in northern Nazko Basin and sedimentation was succeeded by volcanism with the subsequent deposition of the Kasalka Group and Brian Boru Formation. In southern Nazko Basin fluvial sedimentation of the Silverquick formation ceased in the Cenomanian and was replaced by deposition of  141  the volcanic Powell Creek formation. The lower sedimentary division of the Kingsvale Group was suceeded by the upper volcanic unit. In southern Nazko Basin the transition from a sedimentary to a volcanic province appears to have been fairly gradual. Chen rich sediments of the lower unit of the Silverquick formation pass gradationally up to volcanic clast conglomerate of the upper unit, which in turn grades up to volcanics of the overlying Powell Creek formation. In northern Nazko Basin there are no intervening volcanic clast sediments and the transition appears to be fairly abrupt. At this time, in central Nazko Basin, marine deposition of unnamed sediments was replaced by volcanism (Chilcotin B-22-K well), some (or all ?) of which was submarine (Fig. 25c). This period of volcanism continued throughout the Cretacous in northern Nazko Basin (Kasalka Group and Brian Boni Formation). In central Nazko Basin volcanism was suceeded by marine sedimentation (Chilcotin B-22-K well) in the Santonian (Fig. 25d). Marine sedimentation continued in central Nazko Basin until the Maastrichtian when it was suceeded by fluvial sedimentation. Fluvial sedimentation continued until mid Eocene time when sedimentation was again suceeded by volcanism. In southern Nazko Basin volcanism continued until the Santonian and is represented by the Powell Creek volcanics and the upper Kingsvale Group. The aforementioned volcanic rocks, represented by the Kasalka Group, Powell Creek formation, unnamed volcanics (in central Nazko Basin) and possibly the Brian Boni Formation, may have formed a continuous continental volcanic arc (Woodsworth, 1983; Thorkelson and Smith, 1989) during early Late Cretaceous time Strata within the Nazko Basin were deposited during a mid to early Late Cretaceous compressional event (Garver, 1989; Rusmore and Woodsworth, 1991). On the western edge of southern Nazko Basin northeast vergent thrusting occurred  142  from 87 to 84 Ma in strata of the east Waddington thrust belt (Rusmore and Woodsworth, 1991). Strata within the Tyaughton Basin were deformed from 100 to 90 Ma by west vergent thrusts (Glover and Schiarriza, 1987; Garver, 1989; Umhoefer, 1989); and from 90 to 85 Ma by northeast vergent thrusts (Garver, 1989). In northern Nazko Basin strata in the Tahtsa Lake area were affected by northeast vergent thrusts from 100 to 93 Ma (Rusmore and Woodsworth, 1991). Overall, contractional deformation appears to have occurred between 100 and 85 Ma as the Coast Plutonic Complex underwent 250 to 300 km of shortening (Rusmore and Woodsworth, 1991). The timing of this latest Albian to Campanian deformation is correlative with the deposition of the upper Silverquick formation and the Powell Creek volcanics in southern Nazko Basin. Evidence of syndepositional thrusting is seen in the upper unit of the Silverquick formation exposed in Churn Creek: large plutonic boulders eroded from a thrust (?) fault scarp decrease in size and abundance away from the fault (Mahoney et al., 1992). In northern Nazko Basin northeast vergent thrusts put Lower Jurassic Haze1ton Group on top of mid Cretaceous Skeena Group in the Tahtsa Lake area (Rusmore and Woodsworth, 1991). The period of deformation in northern Nazko Basin appears to be shorter than that in southern Nazko Basin as 93 Ma volcanic rocks of the Kasalka Group, exposed in Whitesail map area, are not involved in thrusting (Rusmore and Woodsworth, 1991). H. SUMMARY AND CONCLUSIONS  The Chilcotin-Nechako region lies within the Intermontane belt of British Columbia on the western edge of Stikinia. Within the Chilcotin-Nechako region are up to 3000 m of mid to Upper Cretaceous chert pebble and volcanic clast conglomerate, chert to volcanic rich sandstones, siltstone and shale which make up  143  the Taylor Creek, Jackass Mountain, Battlement Ridge, Kingsvale and Skeena groups plus unnamed sediments of similar age. These sediments are correlatable and were likely deposited in one large basin, defined in this study as the Nazko Basin. Lower Albian to Cenomanian sediments within the Nazko Basin are separated from older sediments by a major hiatus (Jeletzky and Tipper, 1968; Tipper and Richards, 1976; Cookenboo and Bustin, 1989). The base of the Nazko Basin is roughly marked by sediments deposited during an Albian marine transgression that inundated most of central and southern British Columbia (Tipper, 1984). There are however, scattered fluvial deposits underlying the marine sediments including basal conglomerate of the Taylor Creek Group and the Kitsun Creek sediments of the Skeena Group. The stratigraphy of sediments throughout the Nazko Basin is similar: in all areas there are chert rich sediments overlain by volcanics. In southern Nazko Basin the transition from a dominantly sedimentary province to a volcanic one, in the latest Albian to Cenomanian, appears more gradational than in other areas because basal chert rich sediments (lover unit of the Silverquick formation and lower Kingsvale Group) are overlain by volcanic clast rich sediments (upper unit of the Silverquick formation and upper Kingsvale group) prior to grading up to entirely volcanic rocks (Powell Creek formation and Kingsvale Group volcanics). In northern Nazko Basin the transition appears fairly abrupt and volcanic rocks (Kasalka Group) are found directly overlying chert rich sediments (Red Rose division of the Skeena Group). Sediments of the Nazko Basin were deposited during a compressional regime and thrust faults are found within the sediments in both the north and south (Garver, 1989; Umhoefer, 1989; Rusmore and Woodsworth, 1991). In southern Nazko Basin plutonic detritus, derived from fault scarps, is found locally within the  144  upper unit of the Silverquick formation (Mahoney et al., 1992) thus reflecting active basin tectonism. Sediments within the Nazko Basin are both marine and nonmarine and document the changes in extent of a mid to Late Cretaceous sea. Basal sediments are entirely marine and were deposited during the Early Albian transgression. Marine conditions persisted into Cenomanian time in all but the southern portion of the Nazko Basin where marine sediments of the Taylor Creek Group were succeeded by braided, fluvial deposits of the Silverquick formation in the middle Albian. Latest Albian to Cenomanian time, in the Nazko Basin, marks a change in source area and the transition from a sedimentary to a volcanic province. In southern Nazko Basin chert detritus derived from the Cache Creek and Bridge River terranes and metamorphic detritus eroded from the Omineca Belt was replaced by volcanic detritus probably derived from Late to latest Albian (Thorkelson and Rouse, 1989) volcanic rocks of the Spences Bridge Group or Cretaceous volcanics (Hickson, 1992) exposed to the north. By the Early Cenomanian sedimentation had ceased and active volcanism had spread throughout the entire Nazko Basin. Volcanism continued throughout the basin at least until the Santonian. Volcanic rocks deposited during this period, which may have formed a continuous arc (Woodsworth et al., 1983), include the Kasalka Group, Powell Creek formation, Kingsvale Group volcanics, unnamed volcanics and possibly the Brian Boni Formation. During this period marine conditions persisted in central Nazko Basin and some or all (?) of the volcanism was submarine. In the Santonian sedimentation again replaced volcanism in central Nazko Basin and 1200 m of interbedded marine sandstone and shale were deposited from the Santonian to the Maastrichtian. Prior to this study the youngest known marine sediments on the mainland of British Columbia were Albian in age (Tipper, 1984);  145  sediments deposited in central Nazko Basin plainly show that marine conditions lasted at least until the Maastrichtian. Sediments within the Nazko Basin also provide information on the timing of amalgamation of Terranes I and II (of Monger et al., 1982). Sediments of the Taylor Creek and Kingsvale groups contain clasts derived from a westerly source located on the Insular terrane (Jeletzky and Tipper, 1968; Garver, 1989; McLaren, 1990) indicating that the superterranes were linked by Late Aptian to Early Albian time.  146  I. REFERENCES Armstrong, J.E., 1944. Preliminary map Smithers British Columbia. Geological Survey of Canada, Paper 44-23. Armstrong, R.L., 1988. Mesozoic and early Cenozoic magmatic evolution of the Canadian Cordillera. Geological Society of America, Special Paper 218, p 55-91. Cookenboo, H.O. and Bustin, R.M., 1989. Jura-Cretaceous (Oxfordian to Cenomanian) stratigraphy of the north-central Bowser Basin, northern British Columbia. Canadian Journal of Earth Sciences, vol. 26, # 5, p 1001-1012. Cordey, F., Mortimer, N., DeWever, P and Monger, J.W.H., 1987. Significance of Jurassic radiolarians from the Cache Creek terrane, British Columbia. Geology, vol. 15, p 1151-1154. Crawford, M.L., Hollister, L.S. and Woodsworth, G.J., 1987. Crustal deformation and regional metamorphism across a terrane boundary, Coast Plutonic Complex, British Columbia. Tectonics, vol. 6, # 3, p 343-361. Duffell, S., 1959. Whitesail Lake map-area British Columbia. Geological Survey of Canada, Memoir 299, 119 p. Eisbacher, G., 1981. Late Mesozoic-Paleogene Bowser Basin molasse and Cordilleran tectonics, western Canada. In: Miall, A.D. (Ed.), Sedimentation and Tectonics. Geological Association of Canada, Special Paper 23, p 125-151. Folk, R.L., 1974. Petrology of sedimentary rocks. Hemphill Publishing Company, Austin, Texas; 184 P. Garver, J.I., 1989. Basin evolution and source terranes of Albian-Cenomanian rocks in the Tyaughton Basin, southern British Columbia: implications for mid-Cretaceous tectonics in the Canadian Cordillera. PhD thesis, University of Washington, 227 p. Garver, J.I., Schiarizza, P and Gaba, R.G., 1989. Stratigraphy and structure of the Eldorado Mountain area, Chilcotin Ranges, southwestern British Columbia. British Columbia ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1988. Paper 1989-1, p 131-143. Gehrels, G.E. and Greig, CJ., 1991. Late Jurassic detrital zircon link between the AlexanderWrangellia terrane and Stikine and Yukon-Tanana terranes. Geological Society of America, 1991 Annual meeting, San Diego, Abstracts with programs, Abstract 25987, p A434. Glover, J.K. and Schiarizza, P, 1987. Geology and mineral potential of the Warner Pass map area (920/03). British Columbia Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1986. Paper 1987-1, p 157-169. Glover, J.K., Schiarizza, P and Garver, J.I., 1988. Geology of the Noaxe Creek map area (920/02). British Columbia Ministry of Energy Mines and Petroleum Resources, Geological Fieldwork, 1987. Paper 1988-1, p 105-123. Hacquebard, PA., Birmingham, T.H. and Donaldson, J.R., 1967. Petrography of Canadian coals in relation to environment of deposition. Canada Energy, Mines and Resources, Proceedings of the Symposium on the Science and Technology of Coal, Mines Branch, Ottawa, p 84-97.  147 Hickson, C.J., Read, P, Mathews, W., Hunt, JA., Johansen, G. and Rouse, G., 1991. Revised geological mapping of northeastern Taseko Lakes map area, British Columbia. Current Research, Part A, Geological Survey of Canada, Paper 91-1A, p 207-217. Hickson, CJ., (in press 1992). An update on the Chilcotin-Nechako Project and mapping in Taseko Lakes (920) area, west-central, British Columbia. Current Research, Part A, Geological Survey of Canada, Paper 92-1A. Hunt, JA. and Bustin, R.M., 1990. Stratigraphy, organic maturation and source rock potential of Cretaceous strata in the Chilcotin-Nechako region (Nazko Basin). Current Research, Part F, Geological Survey of Canada, Paper 90-1F, p 121-127. Jeletzky, JA. and Tipper, H.W., 1968. Upper Jurassic and Cretaceous rocks of Taseko Lakes map area and their bearing in the geological history of southwestern British Columbia. Geological Survey of Canada, Paper 67-54, 218 p. Kleinspehn, K.L. 1982. Cretaceous sedimentation and tectonics, Tyaughton-Methow Basin, southwestern British Columbia. Ph.D. Thesis Princeton University, 184 p. Leech, W.W., 1910. The Skeena River district. Geological Survey of Canada, Summary Report 1909, Sessional Paper # 26, p 61-68. Leech, W.W., 1911. Skeena River district, Geological Survey of Canada, Summary Report 1910, p 91101. Lindholm, R. C., 1987. A practical approach to sedimentology. Allen and Unwin Inc., Winchester, Mass. U.S.A., 276 p. Maclntyre, D.G., 1985. Geology and mineral deposits of the Tahtsa Lake district, west-central British Columbia. Ministry of Energy, Mines and Petroleum Resources Bulletin 75, 82 p. Mahoney, .J.B., Hickson, C.J., van der Heyden, P and Hunt, JA., (in press, 1992). Stratigraphy of the Late Albian-Early Cenomanian Silverquick Conglomerate, Gang Ranch area: evidence for active basin tectonism. Geological Survey of Canada Paper. McKenzie, KJ., 1985. Sedimentology and stratigraphy of the southern Sustut basin, north central British Columbia. M.Sc. thesis, University of British Columbia, 102 p McLaren, G.P, 1990. A mineral resource assessment of the Chilko Lake planning area. British Columbia ministry of Energy, Mines and Petroleum Resources, Bulletin 81, 117 p Monger, J.W.H., Price, RA. and Tempelman-Kluit, DJ., 1982. Tectonic accretion and the origin of two major metamorphic and plutonic welts in the Canadian Cordillera. Geology, vol. 10, p 70-75. Palsgrove, R.J., 1990. Stratigraphy, sedimentology and coal quality of the lower Skeena Group, Telkwa Coalfield, central British Columbia (93L/11). M.Sc. Thesis, Universiy of British Columbia, Vancouver, 130 p. Parrish, R.R., 1979. Geochronology and tectonics of the northern Wolverine complex, British Columbia. Canadian Journal of Earth Sciences, vol. 16,p 1428-1438. Read, P.B. 1988. Metamorphic map of the Canadian Cordillera. Geological Survey of Canada, Open File 1893.  148  Rice, H.MA., 1947. Geology and mineraldeposits of the Princeton map area, British Columbia. Geological Survey of Canada, Memoir 243. Roddick, JA. and Tipper, H.W., 1985. Mount Waddington, 92N. Geological Survey of Canada Open, File 1163. Rusmore, M.E. and Woodsworth, G.J., 1991. Coast Plutonic Complex: a mid-Cretaceous contractional orogen. Geology, vol. 19, # 9, p 941-944. Rust, B.R. and Koster, E.H., 1984. Coarse alluvial deposits. In, Facies Models, Edited by Walker, R.G. Geoscience Canada Reprint Series 1, p 53-69. Rust, B.R., 1972. Structure and processes in a braided river. Sedimentology, vol. 18, p 221-245. Rust, B.R., 1984. Proximal braidplain deposits in the middle Devonian Malbaie Formation of eastern Gaspe, Quebec, Canada. Sedimentology, vol. 31, p. 675-695. Schiarizza, P, Gaba, R.G., Glover, J.K. and Garver, J.I., 1989. Geology and mineral occurrences of the Tyaughton Creek area (920/2, 92J/15, 16). British Columbia ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork, 1988, Paper 1989-1, p 115-130. Sutherland Brown, A., 1960. Geology of the Rocher Deboule Range, British Columbia. British Columbia ministry of Energy, Mines and Petroleum Resources, Bulletin 43, 78 p Thorkelson, D.J. 1985. Geology of the mid Cretaceous volcanic units near Kingsvale, southwestern British Columbia. In Current Research, Part B, Geological Survey of Canada, Paper 85-1B, p 333-339. Thorkelson, D.J. and Rouse, G.E., 1989. Revised stratigrphic nomenclature and age determinations for mid-Cretaceous volcanic rocks in southwestern British Columbia. Canadian Journal of Earth Sciences, vol. 26, # 10, p 2016-2031. Thorkelson, D.J. and Smith, A.D., 1989. Arc and intraplate volcanism in the Spences Bridge Group: implications for Cretaceous tectonics in the Canadian Cordillera. Geology, vol. 17, p 1093-1096. Tipper, H.W., 1963. Nechako River map area, British Columbia. Geological Survey of Canada, Memoir 324, 59 p. Tipper, H.W., 1969. Mesozoic and Cenozoic geology of the northeast part of Mount Waddington map area (92N), Coast District, British Columbia. Geological Survey of Canada, Paper 68-33, 103 p Tipper, H.W., 1976. Smithers, British Columbia, mapsheet 93L. Geological Survey of Canada, Open File 351. Tipper, H.W., 1978. Taseko Lakes (920) map area. Geological Survey of Canada, Open File 534. Tipper, H.W., 1984. The allochthonous Jurassic-Lower Cretaceous terranes of the Canadian Cordillera and their relations to correlative strata of the North American Craton. In: JurassicCretaceous Biochronology and paleogeography of North America, G.E.G. Westermann (Ed.), Geological Association of Canada, Special Paper 27, p 113-120. Tipper, H.W. and Richards, TA., 1976. Jurassic stratigraphy and history of north-central British Columbia. Geological Survey of Canada, Bulletin 270, 73 p Traverse, A., 1988. Paleopalynology. Unwin Hyman Ltd, London, England, 600 p  149  Umhoefer, PJ., 1989. Stratigraphy and tectonic setting of the upper Cadwallader terrane and overlying Relay Mountain Group, and the Cretaceous to Eocene structural evolution of the eastern Tyaughton Basin, British Columbia. Ph.D. thesis, University of Washington, 186 p Woodsworth, &I, Crawford, M.L. and Hollister, L.S., 1983. Metamorphism and structure of the Coast Plutonic Complex and adjacents belts, Prince Rupert and Terrace areas, British Columbia. Geological Association of Canada - Mineralogical Association of Canada - Canadian Geophysical Union Fieldtrip Guidebook, trip 14, p 5. van der Heyden, P, 1989. U-Pb and K-Ar geochronometry of the Coast Plutonic Complex, 53 ° N-54° N, and implications for the Insular-Intermontane superterrane boundary, British Columbia. Ph.D. thesis, University of British Columbia, Vancouver, 392 p.  150  ABSTRACT - PART H  New data from this study indicate mid to Late Cretaceous sediments within the Chilcotin-Nechako region are zeolite facies. This low grade of metamorphism is probably due to comparatively low heat flow in the Chilcotin-Nechako region. When compared to equivalent strata exposed to the north, sediments within the Nazko Basin have markedly lower maturation values even though they have experienced the same amount of burial. Sediments with zeolite grade metamorphism have the potential to lie within the oil window and thus may contain significant hydrocarbon reserves. However, Rock-Eval pyrolysis and TOC analyses of outcrop and well samples indicate the overall hydrocarbon potential of the Chilcotin-Nechako region is low. However, there are some areas with moderate to good hydrocarbon potential in the Smithers area.  151  PART II: THERMAL MATURATION AND SOURCE ROCK POTENTIAL OF CRETACEOUS STRATA IN THE CHILCOTIN-NECHAKO REGION  A. INTRODUCTION  The Chilcotin-Nechako Region hosts a sedimentary sequence which includes potential petroleum source and reservoir strata. Oil seeps have been found in the Morice River/Lake area (93L/3) and pyrobitumen occurs in quartz veins near Nadina Mountain (93L/2). Nine wildcat wells were drilled in the Nazko and Redstone areas between 1960 and 1986 (Fig. 26). None of the wells showed promising results. However, poorly defined stratigraphy within the ChilcotinNechako region combined with limited exposure make exploration for minerals and hydrocarbons difficult in this area. and leaves the true potential open to question. To date variations in source rock quality and maturation of Cretaceous strata in the Chilcotin-Nechako Region have not been documented. The purpose of this part of the study is to establish the source rock potential and thermal maturity of Cretaceous sedimentary strata in the Chilcotin-Nechako region. Rock-Eval pyrolysis is used here to identify and assess potential source strata and delineate their areal extent. Vitrinite reflectance and Tmax values from Rock-Eval pyrolysis analyses are used to determine maturation levels of predominantly Cretaceous strata within the Chilcotin-Nechako Region and to produce a surface metamorphic map showing areas potentially within the oil window . Five hundred carbonaceous outcrop samples were collected in order to establish lateral variations in organic maturation and source rock potential. In addition 300 samples were collected from well cuttings of the Chilcotin B-22-K and Nazko D-96-E wells to provide information on vertical variation in thermal maturity and Carbon content.  ^  152  CHILCOTIN-NECHAKO REGION  \ omit ers  \  \  REGIONAL SETTING \ 0  ■ c* ,  • Francois ze4.  "k )VanderZ° R  iver  93j \^  , PRINCE GEORGE  Punchaw C-38-J *  93F  so  R ver  e -^ :lest N. 93G % 1 1 '-,^ Nazko^4) 4 OUESNEL I (.., Chilcotih B-22-K^Nazko B - 16 - J it I  \  ^G ^-  ■  ; 0^_96_e*Nazko A-4-L ^( I \-5..... 7 o Na * Zko D • Ananim Lake .\.1. *^,I Nazko B-48-C^\ I  Bella \^Coola \  nanne  i  1 --1-9 ,.:^\. -------7Charlotte^to ^938^'‘I "--) take 9 3C Oi  \,\ _ 93D^\ ——  Redsto ne C-7 5 -A  ■ Alexis Creek  U3 m ( ■ WILLIAMS LAKE 4- I I  Faults and tectonic lineaments Exploration wells *  40 20 0 ^  50 30 10  Scale  50  km  Figure 26 - Location of wild catwells drilled in the Chilcotin-Nechako Region.  (From Hickson 1990).  53o  0,o  153  Samples of well cuttings from the Nazko D-96-E and Chilcotin B-22-K wells were made available by Canadian-Hunter. B. METHODS 1. VITRINITE REFLECTANCE  The degree of organic maturation (DOM) was determined using the vitrinite reflectance techniques outlined in England and Bustin (1986). Samples containing visible coal or organic matter were crushed and analyzed as whole rock samples. Samples with low concentrations of organic material were crushed and demineralized with hydrochloric and hydrofluoric acids. The crushed samples were mounted in epoxy resin or Transoptic forming pellets. The pellets were polished and stored under argon gas to prevent oxidation of the organic matter prior to analysis. The mean random vitrinite reflectance (%Rorand) in oil (n = 1.518 at 546 nm) was measured using a Leitz MPVII microscope. Where possible 50 vitrinite reflectance measurements were made on each sample, and the mean and standard deviation determined. 2. ROCK EVAL PYROLYSIS -  Outcrop and well samples were analysed by Rock-Eval pyrolysis and Total organic carbon (TOC) using a Rock-Eval II pyrolysis instrument. Whole rock samples were crushed to approximately -200 mesh. Shale fragments were hand picked from well cuttings prior to crushing. Coal samples were layered with crushed pure quartz prior to Rock-Eval pyrolysis to prevent carbon caking of the pyrolysis instrument. Interpretations of Rock-Eval pyrolysis data in this study are based on parameters and their experimental limits documented by Tissot and Welte (1984), Espitalie et al. (1985) and Peters (1986).  154  Table 6 is a summary of the various parameters Rock-Eval pyrolysis provides to characterize potential source rocks. During pyrolysis hydrocarbons already present in the rock in a free or adsorbed state are first volatilized at moderate  °  temperatures ( < 300 C). The S1 peak (mg HC/g of rock) representing the amount of these hydrocarbons is measured by a flame ionization detector (FID). Subsequent pyrolysis of kerogen at temperatures between 300 and 600 °C results in the generation of hydrocarbons represented by the S2 peak (mg HC/g of rock), and CO2 represented by the S3 peak (mg CO2/g of rock). The volatile compounds generated are split into two streams passing through a FID that  °  measures S2 and a thermal conductivity detector, operative between 300 and 390 C, that measures S3. During pyrolysis, Tmax, the temperature of maximum S2 hydrocarbon generation is also measured Following pyrolysis the residual organic matter is oxidized at 600°C. The carbon released by this oxidizing process is summed with that from S1, S2 and S3 to give the total organic carbon content (TOC) (Espitalie et al., 1977). The above parameters and others calculated from them (Table 6) can be used to determine the nature and quality of potential source rocks. There are three crucial factors for characterization of a hydrocarbon source rock: the quantity of organic matter, the type or quality of organic matter and its state of maturity (Tissot and Welte, 1984). The quantity of organic matter is determined from the total organic carbon content (TOC) (Table 7). Samples must have a TOC of at least 0.5 wt.% to be considered source rocks (Tissot and Welte, 1984). Samples with low TOC values can cause problems during Rock-Eval analysis. Values of S2 are unreliable if the TOC value is less than 0.5 wt. % because of adsorption of pyrolytic compounds onto  155  MEASURED PARAMETERS S1 = hydrocarbons thermally distilled from the whole rock at temperatures < 300 C. Units: mg of hydrocarbon/gram of rock.  °  S2 = hydrocarbons generated by pyrolytic degredation of kerogen between 300 and 600 °C. Units: mg of hydrocarbon/gram of rock. S3 = a measure of organic CO2 generated between temperatures of 300 and 390  ° C. Units: mg CO2/gram of rock.  Tmax = the temperature of the maximum rate of evolution of pyrolysis  °  hydrocarbons (S2) in C.  TOC = carbon in (S1 + S2 + S3) + carbon from oxidized residual organic  matter  CALCULATED PARAMETERS HCP (hydrocarbon potential) = S1 + S2 PI (production index) = S1/(S1 +S2) HI (hydrogen index) = (S2/TOC) x 100  ()I (oxygen index) = (S3/TOC) x 100 QOM (quality of organic matter) = (S1+ S2)/TOC  Table 6: Measured and calculated parameters derived from Rock-Eval pyrolysis.  156  QUANTITY  POOR  TOC  S1  S2  (wt.%)  (mg HC/g rock)  (mg HC/g rock)  0 - 0.5  0 - 2.5  0 - 2.5  0.5 - 1  0.5 - 1  2.5 - 5  GOOD  1-2  1-2  5-10  VERY GOOD  2+  2+  10 +  FAIR  Table 7: Geochemical parameters describing source rock generative potential (Peters, 1986).  TYPE  HI  S2/S3  (mg HC/g Corg)  GAS (TYPE III OM)  0 - 150  0-3  GAS/OIL (TYPE II OM)  150 - 300  3-5  OIL (TYPE I OM)  300 +  5+  Assuming a level of thermal maturation equivalent to Ro = 0.6% OM = organic matter  Table 8: Geochemical parameters describing the type of hydrocarbon generated (Peters, 1986).  157  the mineral matrix (Peters, 1986). Up to 85% of S2 can be retained by an illite matrix (Peters, 1986). Partial adsorption on clay in the whole rock delays escape of the pyrolyzate, thus resulting in a high Tmax (Peters, 1986). Type III kerogen is most prone to this problem because it generates less pyrolyzate (S2) per gram of organic matter than Types I or II (Peters, 1986). The type or quality of kerogen is characterized by two indices: the hydrogen index (HI) and the oxygen index (0I) (Table 6). The hydrogen and oxygen indices are independent of the abundance of organic matter and are strongly related to the elemental composition of kerogen (Tissot and Welte, 1984). When using the RockEval pyrolysis method the amount of oxygen in the kerogen is proportional to the CO2 liberated during pyrolysis (S3) and the hydrogen content is proportional to the hydrocarbons liberated (S2) (Espitalie et al., 1977). There is good correlation between HI and H/C ratios, and between CH and 0/C ratios respectively (Espitalie et al., 1977; Tissot and Welte, 1984); thus the two indices can be plotted in place of  the normal van Krevelen diagram and interpreted in the same way. In a Van Krevelen diagram different types of kerogen are shown as Type I (very oil prone), Type II (oil and gas prone) and Type III (gas prone). Hydrogen Index values greater than 300 mg HC/g organic carbon suggest oil prone Type I organic matter, values between 150 and 300 suggest oil and gas prone Type II organic matter, and HI values less than 150 mg HC/g organic carbon point to gas prone Type III organic matter, assuming a DOM equivalent of 0.6% (Table 7; Espitalie et al., 1977; Peters, 1986). The thermal maturation of each kerogen type is described by a pathway: the most mature samples are near the lower left corner and have little hydrogen or oxygen relative to carbon in the kerogen (Fig. 27). The ratio (S1+ S2)/TOC can also be used to assess the quality of organic matter as shown in table 9. This ratio, referred to as the quality of organic matter (QOM), is a measure of the type of organic matter and thermal maturity;  158  1,000  900  800  0 700  Figure 27: Modified van Krevelen diagram.  0 CNI^600 CO X Q1 V 500 C C  a) •  400  -02>. 1 300 200  100  0  O  50^100^150^200  ^  250  Oxygen Index (S3/TOC)  QOM  (S1 +S2)/TOC mg HC/g Corg  LOW  < 1.4  MODERATE  1.4 - 3.0  HIGH  > 3.0  QOM = quality of organic matter TOC = total organic carbon  Table 9: Geochemical parameters describing the quality of organic matter  159  high ratios indicate immature to mature hydrogen rich strata. A significant spread in the QOM, which cannot be related to variations in the degree of organic maturation (DOM) or type of organic matter, is considered to reflect the effects of migration of hydrocarbons into or out of the strata (Espitalie et al., 1985). The HI combined with the ratio of S2/S3 can also be used to define the type of organic matter as shown in table 8 (Peters, 1986). The level of thermal maturity can be roughly estimated from the HI versus CH plot described above. Table 10 show how to use the production index (PI) and Tmax to estimate maturity. In the absence of migration the ratio S1/(S1+ S2) is an evaluation of the transformation ratio or PI (Espitalie et al., 1985; Peters, 1986). The PI is the ratio of hydrocarbons actually formed by the kerogen (S1) to the total amount of hydrocarbons that the kerogen is capable of generating (S1+ S2). This ratio depends on the nature of the organic matter and on the subsequent temperature versus time history. In addition to measuring maturation the PI can be used as a quantitative evaluation of hydrocarbons generated (Tissot and Welte, 1984). Both Tmax and the PI increase continuously as a function of depth, making them valuable indices of maturation. In general PI and Tmax values less than about  °  0.1 and 435 C respectively indicate immature organic matter (Peters, 1986). A Tmax greater than 470 °C represents the end of the oil window and the beginning of the wet gas zone (Peters, 1986). The PI reaches about 0.4 at the end of the oil window and increases to 1.0 when the hydrocarbon generating capacity of the kerogen has been exhausted (Peters, 1986). In general, Tmax values cannot be accurately determined if S2 yields are less than 0.2 mg HC/g of rock (Espitalie et al., 1985). Kerogen type also affects Tmax, as do oxidized or highly mature samples. Results from theses types of samples tend to yield abnormally high Tmax values and small or missing S2 peaks (Peters, 1986).  160  MATURATION  PI  TMAX oc  Ro %  TOP OF OIL WINDOW  - 0.1  - 435-445  - 0.6  BOTTOM OF OIL WINDOW  - 0.4  - 470  - 1.4  Table 10: Geochemical parameters describing the maturity of organic matter (Peters, 1986).  HCP  (S1 +S2) mg HC/g rock  NO OIL SOURCE ROCK  < 2  MODERATE SOURCE ROCK  2-6  GOOD SOURCE ROCK  > 6  HCP = hydrocarbon potential  Table 11: Geochemical parameters describing hydrocarbon potential (Tissot & Welte, 1984).  161  Hydrogen index and oxygen index values are also affected by oxidized or highly mature kerogen samples. Oxidation tends to remove hydrogen and add oxygen to the kerogen changing the HI versus OI plot (Peters, 1986). More mature samples may plot higher on a path, in the HI versus OI diagram (Fig 27), than less mature samples due to a loss of hydrogen from the less mature kerogen caused by oxidation (Peters, 1986). In addition to providing information on the quantity, type and maturation of organic matter Rock-Eval data also yields information on the genetic or hydrocarbon potential (HCP) of a rock. The HCP (Table 11) represents the amount of hydrocarbons the kerogen is able to generate if it is subjected to adequate temperature during a sufficient interval of time (Tissot and Welte, 1984). C. RESULTS 1. MATURATION  Vitrinite reflectance values measured for outcrop samples in the ChilcotinNechako region are shown in table 13; Tmax values, from Rock-Eval pyrolysis, are tabulated in table 20. Thermal alteration index (TM) values for the Nazko D-96-E and Chilcotin B-22-K wells, determined prior to palynological analysis, are shown in table 14. Vitrinite reflectance values for mid to Late Cretaceous sediments within the Chilcotin-Nechako region range from 0.41-2.71%; sediments older than mid to Late Cretaceous yielded reflectance values ranging from 1.14 to 1.89%; and reflectance values for younger, Tertiary, sediments range from 0.41-1.13%. TM values for the Nazko D-96-E and Chilcotin B-22-K wells range from 0.5-3.75 and 0.25-4.0 respectively. Tmax values for outcrop samples range from 303 to 568 ° C. However, most outcrop samples yielded S2 values less than 0.2 mg of hydrocarbon/g of rock,  162  Table 12 - Summary of vitrinite reflectance data for outcrop samples in the  Chilcotin-Nechako region.  163  SAMPLE #^GROUP OR FORMATION  AVG Ro  RANK  NORTHERN CHILCOTIN-NECHAKO REGION J89-005-02^Kitsun Creek seds J89-005-05^Kitsun Creek seds J89-005-07^Kitsun Creek seds J89-006-02^Kitsun Creek seds J89-249-03^Kitsun Creek seds J89-249-10^Kitsun Creek seds Red Rose division J89-004-02 J89-004-04 Red Rose division Red Rose division J89-007-01 J89-016-01 Red Rose division J89-017-04 Red Rose division Red Rose division J89-018-01 Red Rose division J89-021-01 J89-022-01 Red Rose division Red Rose division J89-025-01 Red Rose division J89-030-01 J89-030-03 Red Rose division Red Rose division? J89-037-04 Red Rose division? J89-038-01 J89-040-01 Red Rose division? Red Rose division? J89-046-01 J89-054-01 Red Rose division? Red Rose division? J89-055-01 Red Rose division? J89-057-03 J89-062-01 Red Rose division? Red Rose division J89-064-01 Red Rose division J89-068-01 Red Rose division J89-069-01 Red Rose division J89-070-02 Red Rose division J89-072-01 Red Rose division J89-082-01 Red Rose division J89-082-02 J89-085-01 Red Rose division J89-086-02 Red Rose division Red Rose division J89-088-01 J89-106-03 Red Rose division? Red Rose division J89-252-01 Red Rose division J89-262-01 J89-263-01 Red Rose division Red Rose division J89-264-01 J89-265-01 Red Rose division J89-266-01 Red Rose division Red Rose division J89-279-01 Red Rose division J89-279-03 Red Rose division J89-279-05 Red Rose division J89-282-01 J89-282-03 Red Rose division Red Rose division J89-282-07 Red Rose division J89-282-09 J89-282-10 Red Rose division  0.83 1.85 1.91 1.74 1.46 1.32 0.62 1.22 0.71 1.17 0.91 0.90 1.04 1.43 1.30 1.36 0.87 0.49 0.36 1.38 1.47 1.52 0.35 2.09 2.16 1.23  1.01 1.00  1.23 1.13 1.32 2.14 1.80 1.80 1.66 1.04 0.83 0.63 0.58 0.51 0.60 0.86 1.73 1.14 0.70 0.79 1.09 0.90 0.87 0.97  HVB A LVB LVB LVB MVB MVB SUB-BIT A/HVB C MVB HVB B MVB HVB A HVB A HVB A MVB MVB MVB HVB A SUB-BIT A/HVB C LIGNITE MVB MVB LVB LIGNITE LVB MVB HVB A HVB A MVB MVB MVB LVB LVB LVB LVB HVB A HVB A SUB-BIT SUB-BIT SUB-BIT SUB-BIT HVB A LVB MVB HVB B HVB A HVB A HVB A HVB A HVB A  A/HVB A/HVB A/HVB A/HVB  C C C C  ^ ^  164 SAMPLE #^GROUP OR FORMATION AVG Ro RANK  NORTHERN CHILCOTIN-NECHAKO REGION CONTINUED J89-284-01^Red Rose division^1.03^HVB A J89-285-03^Smithers Fmtn^1.52^LVB J89-011-01^Skeena or Ashman^1.14^MVB J89-269-02^Ashman Fmtn^1.54^LVB J89-286-10^Ashman Fmtn^1.69^LVB J89-286-11^Ashman Fmtn^1.55^LVB J89-272-01^mid Paleocene seds^0.46^SUB-BIT B J89-096-02^Tertiary seds^0.68^HVB B J89-164-02^Tertiary seds^1.13^MVB CENTRAL CHILCOTIN-NECHAKO REGION J89-167-01 J89-167-03 J90-001-03 J90-001-04 J90-003-01 J90-003-02 J90-003-03 J90-003-08 J90-006-02  Unnamed Unnamed Unnamed Unnamed Unnamed Unnamed Unnamed Unnamed Unnamed  seds seds seds seds seds seds seds seds seds  0.74 0.41 2.71 0.92 0.82 1.22 1.15 1.20 0.62  HVB B SUB-BIT C HVB A HVB A  SUB-BIT A/HVB C  SOUTHERN CHILCOTIN-NECHAKO REGION J89-173-01^Silverquick fmtn?^1.75^LVB J89-189-01^Silverquick fmtn^0.80^HVB A J89-236-03B^Silverquick fmtn^1.12^MVB J89-236-06^Silverquick fmtn^1.10^HVB A J89-236-07^Silverquick fmtn^1.15^MVB J89-236-09^Silverquick fmtn^0.46^SUB-BIT B J90-012-09^Kingsvale Group^1.15^MVB J89-218-01A^Triassic seds^1.89^LVB J89-218-01B^Triassic seds^1.46^MVB J89-219-04^Triassic? seds^1.80^LVB J89-241-01^Relay Mountain Group 1.73 ^LVB J89-243-02^Relay Mountain Group 1.71^LVB J90-011-07^Relay Mountain Group 1.48 J90-011-16^Relay Mounain Group^1.70 J89-201-02^Eocene seds^0.98^HVB A J89-232-01^Eocene seds^0.41^SUB-BIT C  165  CHILCOTIN B-22-K WELL DEPTH (m)  TAI^METAMORPHIC FACIES  72.5 147.5 170 222.5 325 397.5 465 505 562.5 637.5 717.5 740 807 1052.5 1940 2500 2862.5  0.25 0.25 0.25 0.25 1.0 1.75 1.75 3.5 - 4.0 2.25 1.0 - 1.25 3.5 - 4.0 1.5 - 2.25 2.5 - 2.75 2.25 2.5 2.5 - 2.75 2.8 -^3.0  -^230 -^337.5 -^440 -^485 -^535 -^602.5 -^675 -^720 -^782.5 -^967.5 - 1140 - 2000 - 2545 - 2970  none none none none none none none prehnite-pumpellyite zeolite none prehnite-pumpellyite none to zeolite zeolite zeolite zeolite zeolite zeolite  NAZKO D-96-E WELL DEPTH (m) -^48 -^130 -^190 -^220 -^247.5 -^270.5 -^345 -^987.5 -^997.5 - 1405 - 1625 - 2400  17.5 50 135 195 230 250 290 977 5 992 5 1365 1505 2270  TAI^METAMORPHIC FACIES 0.5 2.5 - 2.8 2.5 -^2.8 2.4 - 2.6 2.5 - 2.7 3.0 -^3.2 3.0 1.25 1.25 3.5 - 3.75 2.5 - 2.8 2.5 -^2.8  none zeolite zeolite zeolite zeolite zeolite zeolite none none prehnite-pumpellyite zeolite zeolite  Table 13 Thermal Alteration Index (TAI) data for samples from a) the Chilcotin -  B-22-K well and b) the Nazko D-96-E well. For more information on strata in these wells see the central Chilcotin-Nechako region section in Part I.  166  and thus the Tmax values are probably inaccurate and should not be used. Lateral surface maturation trends were determined primarily from vitrinite reflectance measurements of outcrop samples collected from all parts of the Chilcotin-Nechako region, with added data provided by Tmax values (samples with S2 > 0.2 only); the results are shown in figure 28. Most of the organic matter found in samples from Cretaceous sediments of the Chilcotin-Nechako region is of Type III, as shown in figure 29, therefore the oil window has been defined as between 0.6% Ro ran d and 1.4% Ro ran d for this study (Dow, 1977). Strata with vitrinite reflectance values < 0.6% Ro rand are considered to be immature and strata with values > 1.4% Ro ran d are considered overmature with respect to hydrocarbon generation and preservation. These values are used in figure 30 which outlines areas in the Chilcotin-Nechako region that are within the oil window and may have hydrocarbon potential. In southern and central Chilcotin-Nechako region areas with Cretaceous strata in the oil window include Churn and Alexis creeks; areas along the Taseko and Chilcotin Rivers; the Nazko area and just south of the Yalakom Fault in Mount Waddington map area (Fig. 30). In northern Chilcotin-Nechako region, areas within the oil window are located between: (1) Francois and Ootsa Lakes; (2) north of Francois Lake; (3) in the Morice Lake-Thautil River area; (4) in HoustonTommy Creek and (5) in the Bulkley Valley-Zymoetz River area (Fig 30). Data from the Chilcotin B-22-K and Nazko D-96-E wells suggests zeolite grade metamorphism extends to depth, hence, strata within these wells may potentialy lie within the oil window and have considerable hydrocarbon potential. 2. SOURCE ROCK POTENTIAL  A petroleum source rock is one which has sufficient generating capability to create economic liquid hydrocarbon reserves. It is well documented that the  CHILCOTI N  ^  .  167  ECTIAKO REGION SL RFACE MATL RATION IMMATURE  Vitrinite Reflectance < 0.6%  MATURE  Vitrinite Reflectance > 0.6 & < 1.4%  OVERMATURE  Vitrinite Reflectance > 1.4% (With Respect to Hydrocarbon Generation)  1.4 °^0.6^  1.32-2.14  50 30 10^50 km CN  Figure 28  Region  -  Surface maturation map for outcrop samples in the Chilcotin-Nechako  168  1,000  900  Type I (oil prone)  800  6 o  Ic:i co  700  Type II (oil & gas prone)  600  X CD "D 500 C C 0) 400 C) 2 300 I 200  ■ Type III (gas prone) ■ ■  100  ■  ■  ■  50^100^150  ^  200  ^  Oxygen Index (S3/TOC) Figure 29: HI versus 01 plot for outcrop samples in the Chilcotin-Nechako region  250  CHILC OTIN  ^  169  NECI- A <0 REGIC\ SURFACE IVIATURATIO_\ IMMATURE  Vitrinite Reflectance < 0.6%  MATURE  Vitrinite Reflectance > 0.6 & < 1.4%  OVERMATURE  Vitrinite Reflectance > 1.4% (With Respect to Hydrocarbon Generation)  I .32 -2.14  40 20 0 50 30 10  Figure 30 Surface maturation map with the oil window shown, for outcrop samples in the Chilcotin-Nechako Region. -  170  petroleum source potential of a unit is controlled by the quantity, quality and maturity of organic matter (Tissot and Welte, 1984; Peters, 1986). Appendices E and F contain Rock Eval pyrolysis data for outcrop samples from the Chilcotin-Nechako region and samples of well cuttings from the Nazko D96-E, Chilcotin B-22-K, Punchaw and Redstone D-94-G and B-82-C respectively. Tables 14 to 18 summarize Rock Eval pyrolysis data for the wells. A summary of Rock Eval pyrolysis data for outcrop samples is shown in table 19. TOC, QOM, HCP, Tmax, PI and HI versus depth and modified Van Krevelen diagrams are plotted in figures 31 to 35 for the above wells. Maps showing lateral variation in TOC, QOM and HCP for outcrop samples in the ChilcotinNechako region are shown in figure 36. (i) NAZKO D-96-E WELL Rocks within the Nazko well (Fig. 13 Part I) include 409 m of basal Cache Creek Group (?), overlain by about 215 m of interbedded, Aptian shale and pebbly sandstone, which is in turn overlain by 2, 670 m of dominantly marine to near shore marine, late middle Albian to Cenomanian (Table 5 Part I) sandstone, shale and chert pebble conglomerate. The sediments are capped by about 30 m of Tertiary volcanics. Twenty five percent of samples from the Nazko D-96-E well have fair to good TOC values (0.5 - 2.07 wt %) (Tables 7 and 14, Fig 31a). However, only 13 samples have QOM values greater than 1.4 mg HC/g Corg (Tables 9 and 14, Fig 31). Of these thirteen, four samples (687.5, 852.5, 1585 and 1605 m) from within the Late Albian unnamed sediments have a HCP > 2 mg HC/ g rock and are moderate source rocks (Table 11, Fig 31d). The remaining nine samples have no oil generating potential but may have some gas potential (Table 11, Fig 31d).  171  Summary of Rock-Eval pyrolysis results for the Nazko D-96-E well. (0 = no measurement)  Table 14  -  172  SUMMARY OF ROCK-EVAL RESULTS FOR THE NAZKO D-96-E WELL DEPTH (m) TMAX^TOC^HCP^QOM^HI^PI S2/S3 0017.50 0060 0095 0130 0130 0142.5 0170 0225 0230 0250 0250 0270 0272.5 0295 0310 0337 0345 0345 0360 0365 0380 0405 0405 0420 0487 0490 0535 0552.5 0558 0590 0592 0602.5 0602.5 0607.5 0607.5 0627.5 0632.5 0652.5 0652.5 0655 0675 0677.5 0677.5 0687.5 0687.5 0692.5 0692.5 0697.5 0697.5  0 400 340 0 305 0 0 0 0 454 0 0 0 0 435 448 437 0 444 443 460 0 447 449 309 449 0 0 0 439 446 300 363 438 439 0 0 394 439 450 446 436 0 336 442 0 438 0 448  0.06 0.25 0.11 0.04 0.24 0.03 0.04 0.02 0.13 0.50 0.03 0.09 0.09 0.09 0.18 0.88 0.77 0.01 1.10 0.48 0.45 0.06 1.10 0.38 0.03 0.02 0.00 0.05 0.00 0.63 0.83 0.04 0.08 0.82 0.56 0.04 0.00 0.11 0.55 0.34 0.54 0.24 0.06 0.14 1.06 0.00 0.23 0.00 0.04  0.08^1.33 0.04^0.16 0.07^0.64 0.02^0.50 0.06^0.25 0.02^0.67 0.01^0.25 0.01^0.50 0.01^0.08 0.05^0.10 0.01^0.33 0.00^0.00 0.01^0.11 0.01^0.11 0.07^0.39 0.63^0.72 0.48^0.62 0.00^0.00 1.91^1.74 0.41^0.85 0.25^0.56 0.01^0.17 0.37^0.34 0.22^0.58 0.06^2.00 0.17^8.50 0.02 ******* 0.02^0.40 0.01 ******* 1.05^1.67 1.54^1.86 0.04^1.00 0.05^0.62 0.74^0.90 0.42^0.75 0.04^1.00 0.01 ******* 0.01^0.09 0.30^0.55 0.16^0.47 0.57^1.06 0.13^0.54 0.01^0.17 0.04^0.29 3.19^3.01 0.00 ******* 0.10^0.43 0.02 ******* 0.02^0.50  50 8 27 0 4 0 0 0 0 8 0 0 0 0 33 56 38 0 161 75 44 0 27 52 66 700 0 0 0 141 162 50 50 75 50 50 0 9 47 38 87 45 0 21 297 0 39 0 25  0.62 0.50 0.67 1.00 0.83 1.00 0.00 0.00 0.00 0.25 0.00 0.00 0.00 0.00 0.17 0.21 0.37 0.00 0.07 0.12 0.21 0.00 0.19 0.09 0.67 0.19 1.00 1.00 0.00 0.15 0.12 0.50 0.25 0.16 0.33 0.50 0.00 0.00 0.13 0.19 0.18 0.17 0.00 0.25 0.01 0.00 0.10 1.00 0.50  0.01 0.01 0.02 0.00 0.03 0.00 0.00 0.00 0.00 0.21 0.00 0.00 0.00 0.00 0.13 0.61 0.27 0.00 2.61 1.09 0.34 0.00 0.42 0.33 0.08 0.48 0.00 0.00 0.00 1.07 5.00 0.14 0.08 0.72 0.84 0.28 0.00 0.07 0.68 1.44 2.76 0.44 0.00 0.30 14.31 0.00 0.64 0.00 0.05  173 SUMMARY OF ROCK-EVAL RESULTS FOR THE NAZKO D-96-E WELL DEPTH (m) 0707.5 0707.5 0712.5 0712.5 0725 0737.5 0742.5 0767.5 0767.5 0785 0797.5 0807.5 0822.5 0837.5 0842.5 0845 0852.5 0875 0877.5 0877.5 0885 0892.5 0897.5 0907.5 0937.5 0945 0947.5 0967.5 0967.5 0977.5 0987.5 1020 1065 1090 1130 1165 1220 1245 1320 1365 1395 1490 1500 1525 1585 1605 1750 1795 1805  TMAX  TOC  HCP  QOM  HI  PI  S2/S3  441 462 441 328 452 442 436 455 439 448 438 452 438 441 441 442 440 451 441 380 444 441 439 439 457 442 439 0 443 447 450 458 0 437 448 452 490 450 444 358 407 461 405 432 457 447 347 454 462  1.04 0.40 0.53 0.10 0.96 0.45 0.29 0.15 0.71 0.78 0.83 0.41 0.48 0.62 1.00 0.85 1.37 0.64 0.98 0.12 0.53 0.79 2.07 0.32 0.25 0.15 0.19 0.09 0.01 0.12 1.83 0.27 0.04 0.52 0.63 0.07 0.69 0.13 0.08 0.21 0.04 0.18 0.30 0.16 0.99 0.99 0.31 0.41 0.22  1.75 0.17 0.65 0.04 0.97 0.22 0.14 0.08 0.41 1.10 0.46 0.13 0.34 0.48 1.63 1.78 2.70 1.46 1.17 0.06 0.63 0.64 0.23 0.24 0.02 0.06 0.09 0.01 0.02 0.02 1.60 0.08 0.02 0.36 0.65 0.03 0.42 0.11 0.06 0.22 0.10 0.11 0.11 0.02 2.69 2.75 0.14 0.21 0.08  1.68 0.42 1.23 0.40 1.01 0.49 0.48 0.53 0.58 1.41 0.55 0.32 0.71 0.77 1.63 2.09 1.97 2.28 1.19 0.50 1.19 0.81 0.11 0.75 0.08 0.40 0.47 0.11 2.00 0.17 0.87 0.30 0.50 0.69 1.03 0.43 0.61 0.85 0.75 1.05 2.50 0.61 0.37 0.12 2.72 2.78 0.45 0.51 0.36  162 37 116 30 93 44 44 46 53 129 46 24 62 70 155 201 190 193 112 25 113 77 10 65 4 26 42 0 100 8 78 22 0 57 90 14 53 61 25 38 75 44 30 6 252 261 22 31 18  0.03 0.12 0.05 0.25 0.07 0.09 0.07 0.12 0.07 0.08 0.15 0.25 0.12 0.08 0.05 0.04 0.03 0.15 0.06 0.50 0.05 0.05 0.09 0.12 0.50 0.33 0.12 0.00 0.50 0.50 0.10 0.25 1.00 0.17 0.12 1.00 0.12 0.30 0.67 0.64 0.70 0.30 0.20 0.50 0.07 0.06 0.50 0.40 0.50  5.28 1.25 3.87 0.42 6.00 1.53 0.50 0.21 0.67 5.31 0.49 0.27 0.60 0.89 4.69 4.88 5.80 4.76 3.33 0.08 2.30 1.79 0.48 0.53 0.08 0.09 0.40 0.00 0.33 0.14 2.71 0.46 0.00 1.00 3.56 0.20 18.50 1.60 0.05 0.57 0.20 1.60 1.28 0.20 9.25 6.47 0.11 0.56 0.25  174 SUMMARY OF ROCK-EVAL RESULTS FOR THE NAZKO D-96-E WELL DEPTH (m) 1830 1895 1910 1950 1995 2040 2075 2100 2115 2160 2210 2225 2330 2345 2375 2400 2467 2487 2507 2510 2520 2607 2645 2647 2665 2785 2802 2805 2817 2835 2930 2955 2967 2987.5 3085 3110 3130 3147 3240 3260 3272 3287 3305 3315  TMAX  TOC  HCP^QOM  HI  PI  S2/S3  401 333 450 0 0 395 0 0 451 458 458 463 459 456 461 462 462 462 460 465 462 468 349 464 463 446 448 460 457 325 0 343 0 451 0 0 0 471 0 390 344 412 0 312  0.26 0.06 0.22 0.05 0.02 0.30 0.03 0.02 0.05 0.34 0.57 0.33 0.44 0.46 0.54 0.32 0.37 0.50 0.31 0.20 0.15 0.08 0.04 0.14 0.17 0.36 0.77 0.55 0.56 0.05 0.02 0.14 0.01 0.05 0.01 0.00 0.01 0.03 0.01 0.00 0.05 0.03 0.01 0.03  0.11^0.42 0.14^2.33 0.23^1.05 0.02^0.40 0.01^0.50 0.10^0.33 0.01^0.33 0.01^0.50 0.03^0.60 0.26^0.76 0.46^0.81 0.20^0.61 0.45^1.02 0.36^0.78 0.47^0.87 0.24^0.75 0.49^1.32 0.34^0.68 0.23^0.74 0.12^0.60 0.18^1.20 0.03^0.38 0.03^0.75 0.16^1.14 0.13^0.76 0.82^2.28 1.80^2.34 1.12^2.04 1.06^1.89 0.17^3.40 0.02^1.00 0.15^1.07 0.02^2.00 0.05^1.00 0.01^1.00 0.01 ******* 0.00^0.00 0.02^0.67 0.01^1.00 0.03 ******* 0.10^2.00 0.01^0.33 0.04^4.00 0.04^1.33  26 83 68 0 0 23 0 0 40 70 73 48 93 67 72 59 102 58 45 50 113 25 25 78 70 158 157 130 132 12C 0 78 100 80 0 0 0 33 0 0 120 33 200 100  0.40 0.64 0.36 1.00 0.00 0.30 0.00 0.' 0. 0.L.) 0.09 0.20 0.09 0.14 0.17 0.21 0.22 0.15 0.41 0.17 0.06 0.50 1.00 0.31 0.08 0.30 0.33 0.36 0.30 0.69 1.00 0.29 0.50 0.25 0.00 0.00 0.00 0.50 0.00 1.00 0.40 0.00 0.50 0.25  0.58 0.16 0.46 0.00 0.00 0.77 ,...-.,. 3.42 6.00 1.45 4.10 2.58 3.90 2.37 6.14._ 0.60 0.83 2.42 2.00 0.03 1.22 1.33 2.71 3.78 2.11 5.28 0.31 0.00 0.18 0.33 0.21 0.00 0.00 0.0C 0.0c 0.00 0.03 0.28 0.04 0.09 0.15  175  Figure 31 Rock-Eval results for the Nazko D-96-E well.  a) TOC versus depth plot b) Tmax versus depth plot c) HI versus depth plot d) HCP versus depth plot e) PI versus depth plot f) QOM versus depth plot g) OI versus HI plot  Solid square = sample with S2 > 0.2 mg of hydrocarbon/g of rock Solid triangle = sample with S2 < 0.2 Solid circle = no distinction made between S2 values  176 NAZKO D-96-E WELL  ^  NAZKO D-96-E WELL  350^400^450^500  °  ^  TMAX ( C)  a)  ^  b)  NAZKO D-96-E WELL  NAZKO D-96-E WELL  I^I  2  5^10^20^50^100  HI  c)  d)  550  ^  600  177  NAZKO D-96-E WELL  ^  NAZKO D-96-E WELL  0  500  1.000  E I H n. 0  1,500  2000  2.500  3.000  3.500 0.03^0.1^0.3^1^3  e)  ^  QOM  f)  NAZKO D-96-E WELL  g  50^100^150^200^250  Oxygen Index (S3/TOC)  )  10  30  178  Tmax values for samples from 687.5, 852.5 and 1605 m suggest they are just at the start of the oil window however; PI values (0.01, 0.03 and 0.06 respectively) indicate the samples are immature with respect to hydrocarbon generation (Table  °  10, Figs 31b and e). The sample from 1585 m depth has a Tmax of 457 C suggesting it is mature and lies within the oil window. The PI value (0.07) indicates this sample is immature and has not yet reached the oil window. These conflicting results may be due to migration of earlier formed (S1) hydrocarbons out of the strata. This would cause an unrealistically small Si peak to be generated during Rock-Eval pyrolysis. Kerogen in the Nazko D-96-E well is dominantly Type III with minor amounts of Type II (Figs 31c and g). Using the S2/S3 ratio to define organic matter type (Peters, 1986) several samples are classified as Type I (Table 8). HI values for the four samples with hydrocarbon potential (687.5, 852.5, 1585 and 1605) indicate they have type II (oil and gas prone) kerogen; the S2/S3 ratios suggest type I (oil prone) organic matter. (ii) CHILCOTIN B-22-K WELL Rocks within the Chilcotin well (Fig. 13, Part I) include about 1400 m of Cenomanian (?) to Santonian volcanic rocks overlain by 1600 m of dominantly near shore marine to transitional marine, Santonian to Maastrichtian (Table 5 Part I) sandstone and shale. Overlying the marine sedimentary sequence are about 140 m of non marine, Eocene sandstone and shale capped by 580 m of mid Eocene to Early Miocene volcanic rocks. The majority of samples from the Chilcotin B-22-K well have low TOC values ( < 0.5 wt %) and cannot be considered source rocks (Table 15, Fig 32a). Two samples, from 147.5 and 210 m depths, within Early Miocene volcanic rocks, have good to very good TOC values of 4.63 and 1.06 wt % respectively (Table 7).  179  Table 15 Summary of Rock-Eval pyrolysis results for the Chilcotin B-22-K well. -  (0 = no measurement)  180  SUMMARY OF ROCK-EVAL RESULTS FOR THE CHILCOTIN B-22-K WELL DEPTH (m) 0040 0047.5 0050 0055 0072.5 0082.5 0112.5 0147.5 0170 0207.5 0210 0222.5 0230 0262.5 0272.5 0290 0317.5 0325 0337.5 0380 0382.5 0397.5 0425 0427.5 0437.5 0440 0465 0467.5 0470 0477.5 0485 0505 0510 0522.5 0535 0542.5 0542.5 0562.5 0562.5 0577.5 0587.5 0602.5 0637.5 0665 0675 0717.5 0720 0740 0752.5  TMAX  TOC  HCP^QOM  HI  PI  S2/S3  0 0 0 0 0 0 0 420 432 388 428 0 0 0 0 0 0 363 0 348 354 0 0 0 0 0 0 0 444 0 0 421 0 0 0 0 0 0 478 0 0 416 353 423 455 451 387 340 450  0.00 0.03 0.01 0.00 0.05 0.00 0.00 4.63 0.14 0.20 1.06 0.08 0.11 0.00 0.06 0.03 0.00 0.10 0.03 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 0.04 0.01 0.04 0.06 0.00 0.00 0.00 0.00 0.05 0.13 0.00 0.02 0.12 0.10 0.01 0.08 0.02 0.09 0.01 0.00  0.02 ******* 0.07^2.33 0.03^3.00 0.01 ******* 0.07^1.40 0.04 ******* 0.07 ******* 9.38^2.03 0.10^0.71 0.02^0.10 0.04^0.04 0.00^0.00 0.00^0.00 0.01 ******* 0.00^0.00 0.12^4.00 0.01 ******* 0.06^0.60 0.01^0.33 0.46^11.50 0.12 ******* 0.03 ******* 0.01 ******* 0.00 ******* 0.01 ******* 0.07 ******* 0.01 ******* 0.00 ******* 0.35^4.38 0.00^0.00 0.03^3.00 0.15^3.75 0.01^0.17 0.02 ******* 0.03 ******* 0.02 ******* 0.03 ******* 0.01^0.20 0.18^1.38 0.01 ******* 0.04^2.00 0.06^0.50 0.04^0.40 0.10^10.00 0.40^5.00 0.06^3.00 0.12^1.33 0.13^13.00 0.04 *******  0 0 0 0 0 0 0 196 64 5 1 0 0 0 0 0 0 10 0 525 0 0 0 0 0 0 0 0 375 0 0 275 0 0 0 0 0 0 107 0 50 33 30 700 437 100 77 700 0  1.00 1.00 1.00 0.00 1.00 0.75 1.00 0.03 0.10 0.50 0.50 0.00 0.00 0.00 0.00 1.00 0.00 0.83 0.00 0.54  0.00 0.00 0.00 0.00 0.00 0.05 0.00 3.33 0.47 0.08 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.11 0.00 0.51  0.58  1.00 0.00 0.00 0.00 1.00 0.00 0.00 0.15 0.00 1.00 0.29 0.00 1.00 1.00 1.00 1.00 0.00 0.22 0.00 0.75 0.33 0.25 0.30 0.12 0.67 0.42 0.50 0.50  0.45  0.00 0.00 0.00 0.00 0.16 0.00 0.00 1.36 0.00 0.00 0.30 0.00 0.00 0.00 0.00 0.14 0.00 0.36 0.00 0.12 0.22 0.07 0.30 1.00 0.10 0.30 0.36 0.09  181 SUMMARY OF ROCK-EVAL RESULTS FOR THE CHILCOTIN B-22-K WELL DEPTH (m) TMAX^TOC^HCP^QOM^HI^PI 0755 0772.5 0782.5 0807 0830 0832.5 0852.5 0870 0875 0885 0920 0922.5 0935 0937.5 0955 0967.5 1052.5 1082.5 1132.5 1132.5 1140 1172.5 1187.5 1192.5 1200 1210 1242 1267.5 1297.5 1317.5 1342.5 1355 1395 1425 1435 1482.5 1485 1502.5 1527.5 1560 1562.5 1600 1607 1657.5 1675 1695 1700 1725 1760  378 0 365 405 332 374 339 456 300 436 453 0 0 0 426 489 429 447 452 425 452 437 480 333 0 453 0 406 459 558 449 449 0 351 347 0 305 398 0 405 372 305 350 305 322 0 371 326 305  0.00 0.00 0.00 0.00 0.08 0.08 0.01 0.04 0.01 0.02 0.05 0.00 0.01 0.00 0.10 0.09 0.09 0.08 0.06 0.04 0.07 0.07 0.07 0.00 0.01 0.06 0.03 0.04 0.05 0.04 0.00 0.00 0.00 0.02 0.08 0.02 0.04 0.07 0.03 0.04 0.00 0.03 0.27 0.04 0.17 0.02 0.08 0.03 0.04  0.08 ******* 0.01 ******* 0.04 ******* 0.07 ******* 0.04^0.50 0.24^3.00 0.05^5.00 0.19^4.75 0.08^8.00 0.17^8.50 0.31^6.20 0.01 ******* 0.04^4.00 0.01 ******* 0.31^3.10 0.27^3.00 0.36^4.00 0.40^5.00 0.12^2.00 0.11^2.75 0.26^3.71 0.32^4.57 0.18^2.57 0.07 ******* 0.07^7.00 0.02^0.33 0.00^0.00 0.11^2.75 0.11^2.20 0.11^2.75 0.02 ******* 0.04 ******* 0.00 ******* 0.10^5.00 0.26^3.25 0.02^1.00 0.04^1.00 0.04^0.57 0.00^0.00 0.08^2.00 0.02 ******* 0.03^1.00 2.25^8.33 0.06^1.50 0.06^0.35 0.08^4.00 0.23^2.88 0.15^5.00 0.03^0.75  0 0 0 0 25 112 400 375 400 600 540 0 0 0 220 233 300 312 200 200 342 328 200 0 200 16 0 250 80 225 0 0 0 400 187 50 50 28 0 125 0 33 81 75 17 200 112 333 50  0.50 0.00 0.50 0.33 0.50 0.62 0.25 0.22 0.50 0.31 0.13 0.00 1.00 0.00 0.30 0.23 0.25 0.37 0.00 0.30 0.08 0.28 0.22 0.33 0.83 0.50 0.00 0.10 0.70 0.20 0.50 0.25 0.00 0.20 0.42 0.50 0.50 0.50 0.00 0.37 0.50 1.00 0.91 0.50 0.50 0.50 0.64 0.36 0.50  S2/S'  0...., 0.00 0.18 0.71 0.18 0.75 0.22 0.53 0.33 1.01.58 0.00 0.00 0.00 0.84 1.50 0.50 0.83 0.00 0.26 0.88 0.54 0.36 0.15 0.50 0.05 0.00 1.25 0.40 2.2: 0.08 0.50 0.00 1.60 1.07 0.07 0.08 0.06 0.00 0.16 0.04 0.16 1.15 0.12 0.06 0.14 0.31 0.43 0.14  182 SUMMARY OF ROCK-EVAL RESULTS FOR THE CHILCOTIN B-22-K WELL DEPTH (m) 1760 1800 1845 1852.5 1872.5 1872.5 1902.5 1940 1957.5 2000 2015 2027.5 2067.5 2082.5 2112.5 2125 2157.5 2172 2190 2207.5 2210 2257.5 2270 2270 2292.5 2317.5 2342.5 2380 2395 2454 2500 2545 2600 2630 2687.5 2720  TMAX  TOC  HCP  QOM  HI  PI  444 0 406 403 305 305 0 400 0 0 452 361 0 305 323 386 365 304 383 423 403 311 0 351 0 397 304 0 305 305 0 305 0 0 0 0  0.03 0.01 0.02 0.02 0.03 0.04 0.02 0.03 0.02 0.02 0.01 0.01 0.02 0.02 0.01 0.02 0.03 0.01 0.03 0.04 0.04 0.03 0.02 0.05 0.01 0.02 0.04 0.02 0.08 0.12 0.04 0.03 0.02 0.01 0.01 0.02  0.10 0.02 0.06 0.12 0.10 0.19 0.00 0.08 0.01 0.01 0.04 0.06 0.01 0.02 0.04 0.07 0.13 0.03 0.21 0.08 0.20 0.12 0.04 0.10 0.03 0.09 0.12 0.03 0.26 0.02 0.05 0.09 0.04 0.01 0.04 0.01  3.33 2.00 3.00 6.00 3.33 4.75 0.00 2.67 0.50 0.50 4.00 6.00 0.50 1.00 4.00 3.50 4.33 3.00 7.00 2.00 5.00 4.00 2.00 2.00 3.00 4.50 3.00 1.50 3.25 0.17 1.25 3.00 2.00 1.00 4.00 0.50  266 0 250 300 133 175 0 200 0 0 200 400 0 50 200 200 300 200 533 125 400 200 50 100 100 200 125 50 187 8 25 33 0 0 0 0  0.20 1.00 0.17 0.50 0.60 0.67 0.00 0.25 0.00 0.00 0.50 0.33 0.00 0.50 0.50 0.50 0.33 0.50 0.25 0.37 0.20 0.50 0.75 0.50 1.00 0.62 0.58 1.00 0.42 0.50 1.00 1.00 1.00 0.00 1.00 0.00  S21._ 0.27 0.00 0.19 0.26 0.30 0.23 0.00 0.24 0.00 0.00 0.11 0.25 0.00 0.07 0.08 0.36 0.64 0.28 1.14 0.16 1.45 0.24 0.06 0.20 0.08 0.26 0.16 0.02 0.5: 0.06 0.01 0.06 0.00 0.00 0.00 0.00  183  Figure 32 - Rock-Eval results for the Chilcotin B-22-K well.  a) TOC versus depth plot b) Tmax versus depth plot c) HI versus depth plot d) HCP versus depth plot e) PI versus depth plot f) QOM versus depth plot g) 01 versus HI plot  Symbols as in figure 31  184  CHILCOTIN B-22-K WELL ^ CHILCOTIN B-22-K WELL 0  411-•■•■=1L- y.  500 1,000  E  E  tow  1,500  a_ w 0  a 2,000 1,500 2,500  3,000 ^ 0.003^0.01^0.03  0.1^0.3^1  3  2,000 10^250^300^350^400^450  °  500  550  TMAX ( C)  TOC  b)  a) CHILCOTIN B 22 K WELL -  CHILCOTIN 8-22-K WELL  -  0  500  1,000 I-  1.000  E 0 w  E 1,500  1.500  w  0 2,000  2,000  2.500  2,500  3.000  200  c)  400 HI  600^800^3.000 0.001  001  0.1  10  HCP  d)  100  185 CHILCOTIN B-22-K WELL  ^  CHILCOTIN 8-22-K WELL  1.000  E 1,500  0  w  0  2,000  2,500  3,000 0.01  12  e)  0.03  fl  CHILCOTIN B-22-K WELL 1,000 900  800  700  g)  600  •  400  ■^  200  •  0  •■ • AA •A•  MI  TYPE III (GAS PRONE)  100  •  ■ EA •••  300  •  •  AA A• A A  AA  —  A  5^10^20^50 100 200^500 1,000  Oxygen Index (S3/TOC)  0.3^1  QOM  ^  500  0.1  3  10  30  186  The sample from 147.5 m has a HCP of 9.38 mg HC/g of rock indicating good source potential (Table 11, Fig 32d); the QOM is 2.03 suggesting a moderate quality source rock (Table 9, Fig 320. The sample from 210 m has a good TOC value (Table 7); however, the HCP and QOM are low (0.04) indicating no oil source rock but possibly some gas potential. The Tmax and PI values (420 ° C and 0.03 respectively) for the sample from 147.5 m suggest it is immature and has not yet reached the oil window (Table 10, Figs 32b and e). Samples from the Chilcotin B-22-K well contain dominantly Type III kerogen based on a HI versus OI plot (Fig 32g). If the classification were based on a HI versus depth plot about two thirds of the samples would be classed as Type I or II (Fig 32c). HI and S2/S3 ratios for the two samples with high TOC values (147.5 and 210 m) indicate they have type II (oil and gas prone) and type III (gas prone) kerogen respectively. (iii) REDSTONE D-94-G WELL Data from well PIX indicate the D-94-G well consists of 2165 m of Albian to Cenomanian Kingsvale Group sediments. For a description of these sediments see figure 22 in Part I and accompanying text. Strata within the Redstone D-94-G well have fair to very good TOC values (0.74-2.84 wt %) as shown in table 16 and figure 33a. However, in most samples petroleum potential is poor due to low QOM ( < 1.4 mgHC/g orgC) and HCP ( < 2 mg HC/g rock) values (Tables 9 and 11, Figs 33d and f). Samples with moderate source potential occur at 410 and 1030 m depths within the Kingsvale Group sediments. The sample from 1030 m has a HCP of 3.66  187  Table 16 Summary of Rock-Eval pyrolysis results for the Redstone D-94-G well. (0 = no measurement) -  188  SUMMARY OF ROCK-EVAL RESULTS FOR THE REDSTONE D-94-G WELL DEPTH (m) TMAX^TOC^HCP^QOM^HI^PI S2/S3 30.0 55.0 90.0 125.0 150.0 170.0 205.0 240.0 270.0 295.0 325.0 375.0 410.0 465.0 510.0 530.0 555.0 615.0 685.0 745.0 845.0 945.0 975.0 995.0 1030.0 1075.0 1100.0 1125.0 1150.0 1180.0 1215.0 1250.0 1325.0 1360.0 1405.0 1600.0 1640.0 1680.0 1745.0 1780.0 1810.0 1835.0 1870.0 1910.0 1945.0 1975.0 2020.0 2060.0  465 443 466 463 459 463 470 472 467 467 454 461 432 494 514 465 500 445 520 468 445 491 416 518 431 439 480 375 467 447 448 470 416 411 422 491 501 427 502 457 507 476 472 459 499 427 406 371  2.57 0.74 1.06 1.89 1.87 1.31 2.21 2.84 1.92 2.33 1.91 2.44 1.88 1.27 1.32 1.64 1.37 1.62 1.50 1.21 1.19 1.51 1.39 1.66 2.53 1.36 1.74 1.50 1.48 1.68 1.52 1.28 1.73 1.50 1.64 1.39 1.40 2.11 1.52 1.56 1.32 1.68 1.35 1.51 1.43 1.60 1.50 1.24  1.99 0.70 0.42 1.34 1.07 0.63 1.70 1.80 1.60 1.62 1.41 1.48 2.29 0.55 0.40 0.61 0.49 0.96 0.46 0.45 0.69 0.67 0.91 0.45 3.66 1.05 0.57 1.12 0.58 1.33 0.60 0.76 0.90 0.90 0.57 0.60 0.59 1.18 0.70 0.71 0.50 0.77 0.45 0.70 0.61 1.02 1.17 0.98  0.77 0.95 0.40 0.71 0.57 0.48 0.77 0.63 0.83 0.70 0.74 0.61 1.22 0.43 0.30 0.37 0.36 0.59 0.31 0.37 0.58 0.44 0.65 0.27 1.45 0.77 0.33 0.75 0.39 0.79  66 71 31 47 46 36 57 48 59 53 49 40 107 35 25 26 29 37 19 23 36 35 46 19 117 62 23 40 29 47  0.39  27  0. 30  0.59 0.52 0.60 0.35 0.43 0.42 0.56 0.46 0.46 0.38 0.46 0.33 0.46 0.43 0.64 0.78 0.79  32 44 36 25 32 30 48 29 28 28 27 19 30 29 43 32 51  0.45 0.14 0.39 0.29 0.25 0.28 0.13 0.36 0.39 0.26 0.39 0.43 0.34 0.32 0.31 0.59 0.35  0.14 0.24 0.21 0.34 0.19 0.24 0.25 0.23 0.29 0.23 0.33 0.33 0.12 0.19 0.17 0.30 0.19 0.37 0.37 0.36 0.37 0.21 0.29 0.27 0.19 0.19 0.29 0.46 0.24 0.40  1.83 3.11 0.91 2.54 8.70 0.87 2.20 2.55 1.50 5.16 9.50 8.25 1.57 1.32 0.22.04 3.33 1.25 1.26 0.18 4.00 0.46 2.50 0.34 1.78 1.93 1.70 2.30 0.60 1.73 2.33  1.40 5.92 1.71 0.68 3.21 14.33 1.51 0.95 4.88 1.05 0.60 0.42 5.11 5.25 1.0 0.5 2.46 '  189  Figure 33 Rock-Eval results for the Redstone D-94-G well  a) TOC versus depth plot b) Tmax versus depth plot c) HI versus depth plot d) HCP versus depth plot e) PI versus depth plot f) QOM versus depth plot g) OI versus HI plot  Symbols as in figure 31  190  REDSTONE D-94-G WELL  ^  REDSTONE D-94-G WELL  E w  2  05  3  5  350^400^450^500  °  TOC  550  TMAX ( C)  a)  b)  REDSTONE D-94-G WELL  ^  REDSTONE D-94-G WELL  E w  10^20^30^50  100  200  03  HI  c)  ^  2  0.5  HCP  d)  3  600  191  REDSTONE D-94-G WELL ^  REDSTONE D-94-G WELL  0  ^•  1,000  E  1,500  2,000  2,500  01^ 0.2^03^0.5^07^  PI  2,500 02  0.3  0.5  fl  e)  REDSTONE D-94-G WELL 1,000 TYPE I (OIL PRONE)  C)  700  TYPE II (OIL & OAS PRONE)  0  9  O  Sp  100  1  QOM  TYPE III (GAS PRONE)  ^,---.^I 50^100^150^200^250  Oxygen Index (S3/TOC)  )  2  192  mg HC/g of rock and a QOM of 1.45 mg HC/g Corg indicating it is a moderate source rock. The Tmax of this sample is 431°C indicating it is very close to the oil window, the PI value (0.19) suggests it is just inside the oil window (Table 10, Figs 33b and e). The sample from 410 m has a HCP of 2.29 indicating a moderate source rock; however, the QOM is low (1.22). The Tmax of this sample is 432°C suggesting it is immature with respect to hydrocarbon generation, the PI (0.12) indicates this sample is just inside the oil window (Table 10, Figs 33b and e). Kerogen in the Redstone D-94-G well is Type III (Figs. 33c and g). If the S2/S3 ratio is used to define organic matter type (Peters, 1986) several samples would be classified as Type I or II. HI and S2/S3 ratios for the two samples with source rock potential indicate they contain type III (gas prone) kerogen. (iv) REDSTONE B-82-C WELL Data from well PIX indicates that sediments within the B-82-C well consist of 350 m of Aptian to Albian sediments of the Jackass Mountain Group (from 1279 1635 m), overlain by volcanic rocks and underlain by intrusive rocks. The Jackass Mountain Group consists of basal, interbedded Aptian greywacke, pebble conglomerate and siltstone about 300 m thick, overlain by up to 900 m of granitic boulder conglomerate interbedded with lesser amounts of greywacke, shale and siltstone (Jeletzky and Tipper, 1968). Overlying the boulder conglomerate are up to 3000 m of interbedded greywacke, arkose, siltstone and shale with lesser pebble conglomerate (Jeletzky and Tipper, 1968). Strata within the Redstone B-82-C well have poor to very good TOC values (0.09 to 9.12 wt. %) as shown in table 17 and figure 34a. However, most samples yielded low QOM and HCP values (Figs 34d and f). Potential source strata do exist  193  SUMMARY OF ROCK-EVAL RESULTS FOR THE REDSTONE B-82-C WELL DEPTH (m)  TMAX  TOC  HCP  QOM  HI  PI  S2/S3  577.50 817.50 1225.00 1277.50 1310.00 1332.50 1370.00 1390.00 1412.50 1452.50 1485.00 1515.00 1595.00 1635.00 1680.00  354 340 420 423 357 426 432 434 432 430 438 435 426 431 438  0.11 0.12 1.10 0.51 0.09 0.86 2.13 2.84 1.85 0.50 4.65 1.62 0.92 1.91 9.12  0.39 0.24 1.04 0.43 0.15 0.71 7.28 12.55 5.49 0.65 4.71 1.46 0.49 0.95 8.85  3.55 2.00 0.95 0.84 1.67 0.83 3.42 4.42 2.97 1.30 1.01 0.90 0.53 0.50 0.97  90 108 68 45 66 70 327 432 282 114 98 72 44 44 94  0.76 0.46 0.28 0.48 0.64 0.14 0.04 0.02 0.05 0.12 0.03 0.20 0.17 0.11 0.02  0.43 0.86 1.78 0.41 0.40 1.45 26.84 32.31 10.25 4.38 3.40 1.32 2.56 4.25 7.20  Table 17 Summary of Rock-Eval pyrolysis results for the Redstone B-82-C well. -  (0 = no measurement)  194  Figure 34 - Rock-Eval results for the Redstone B-82-C well  a) TOC versus depth plot b) Tmax versus depth plot c) HI versus depth plot d) HCP versus depth plot e) PI versus depth plot f) QOM versus depth plot g) OI versus HI plot  Symbols as in figure 31  195  REDSTONE B-82-C WELL  ^  REDSTONE B-82-C WELL  1.200  1,300  1,600  ti  1,700  1^i^  0.03  !  0.1^0.3^3^10  1.800 300  30  350^400^450  TOC  500  TMAX (cC)  a)  b)  REDSTONE B-82-C WELL  ^  REDSTONE B-82-C WELL  800 -  800  E  E tow  Is"  a_ 1,200 -  0  1,400  1,400 --  1,600 -  1.000 -  1.800 1,800 30^ 50  01^0.2^0.5^1^2  100^200^300^500  HCP  HI  C)^  d)  10  20  196  REDSTONE B-82-C WELL ^ REDSTONE 5-82-C WELL  600  1,000  t000  I  I  a  1,200  1.200  1,400  1,400  1,600 -  1.600  1.800 1,800 ^ ^ ^ ^ 03 0.5 0.01 0.03^0.1^0.3 ^ ^ 0.02 0.05^0.2^0.5 QOM  PI  e)  ^  fl  REDSTONE B-82-C WELL 1,000  900  800  700  g  600  500  400  300  200  100  0  0^50^100^150^200  Oxygen Index (S3/TOC)  ^  250  )  2^3^5  197  at depths of 1370, 1390 and 1412 m within the Jackass Mountain Group (Table 17). Of these three samples two (1370 and 1390 m) have high QOM values and one (1412 m) has a moderate QOM value. Tmax values for these three samples are 432, 434 and 432 °C respectively suggesting they are just entering the oil window (Table 10, Fig 34b). PI values (0.04, 0.02 and 0.05 respectively) indicate the samples are immature (Fig 34e). This discrepancy between Tmax and PI values may be due to the effects of migration which cause PI values to be too small. Kerogen in the Redstone B-82-C well is dominantly Type III with minor amounts of Type I and II (Figs. 34c and g). Using the S2/S3 ratio to define organic matter type (Peters, 1986) classifies about half of the samples as Type I or II (Table 8). HI and S2/S3 ratios for samples with good hydrocarbon potential (1370 and 1390 m) indicate they contain type I (oil prone) kerogen. The HI value for the sample with moderate source rock potential (1412 m) indicates it has type II (oil and gas prone) kerogen; the S2/S3 ratio suggests type I. (v) PUNCHAW WELL Data from well PIX indicate this well is structurally complex with numerous faults at the base. Basal Triassic rocks are overlain by Cache Creek Group rocks which are overlain by Paleocene rocks. These Paleocene rocks are in turn are overlain by rocks of the Hazelton Group, which are overlain by rocks of the Cache Creek Group. The well is capped by 550 m of recent strata. Strata within the Punchaw well have fair to very good TOC values (0.59 to 12.39 wt %) as shown in table 18 and figure 35a. However, most samples have low QOM and HCP values (Figs 35d and f). Samples with moderate HCP occur at 620,  SUMMARY OF ROCK-EVAL RESULTS FOR THE PUNCHAW WELL  198  DEPTH (m) TMAX^TOC^HCP^QOM^HI^PI S2/S3 620.00 1080.00 1290.00 1480.00 1710.00 1800.00 2170.00 2700.00 2880.00 3050.00 3090.00 3160.00 3230.00 3300.00 3390.00 3590.00 3850.00  395 390 362 441 356 381 359 396 -1 411 429 401 454 435 459 416 426  0.86 1.26 12.39 0.59 0.85 3.20 3.71 0.66 0.98 1.24 1.20 0.98 1.74 1.35 1.52 0.85 0.65  4.56 1.73 15.53 0.42 0.73 1.14 2.15 1.18 0.66 1.12 1.53 1.99 2.18 1.25 3.43 0.98 1.21  5.30 1.37 1.25 0.71 0.86 0.36 0.58 1.79 0.67 0.90 1.28 2.03 1.25 0.93 2.26 1.15 1.86  174 94 101 23 36 21 38 107 0 41 78 129 101 92 187 57 113  Table 18 - Summary of Rock-Eval pyrolysis results for the Punchaw well.  (0 = no measurement)  0.67^1.72 0.31^0.48 0.19^0.61 0.67^0.07 0.58^0.16 0.39^17.50 0.34^1.09 0.40^1.00 1.00 ******* 0.54^1.16 0.39^0.46 0.36^1.00 0.19 ******* 0.00^0.12 0.17 ******* 0.50^0.91 0.39^0.73  199  Figure 35 - Rock-Eval results for the Punchaw well  a) TOC versus depth plot b) Tmax versus depth plot c) HI versus depth plot d) HCP versus depth plot e) PI versus depth plot f) QOM versus depth plot g) OI versus HI plot  Symbols as in figure 31  200 PUNCHAW WELL  ^  PUNCHAW WELL  0  1,000  2.000  E a_ 0  E a. 0  w  w  3,000  4,000  5.000  0 5^  2^5  10  20  TOC  a)^ PUNCHAW WELL  b)  ^  PUNCHAW WELL  1,000  2,000  E  w  0  3,000  4,000  5,000  10  20 30  50 HI  100  c)^  200 300  02^0.5^1^2^  HCP  d)  10^20  201 PUNCHAW WELL  PUNCHAW WELL  1,000  1, 000  2.000  E w a  3,030  3.000  4,000  4,000  5,000  2.000  01  0.7^  0.5  0.2^0.3  5.000 ^^ 03 0.5  PI  e)  fl  PUNCHAW WELL 1,000  TYPE I (OIL PRONE)  TYPE II (OIL & OAS PRONE)  700  g  • 100^  2^3  QOM  •  TYPE III (OAS PRONE) •  •^■  • 60^100^110^200^260  Oxygen Index (S3/TOC)  )  5^10  202  2170, 3230 and 3390 m (Table 18). One sample at 1290 m depth has good source rock potential (HCP = 15.53). Of these five samples only two have QOM values greater than 0.4. The sample from 620 m has a high QOM value of 5.30 and the sample from 3390 m has a moderate QOM value of 2.26. Tmax values for these two samples are 395 and 459 ° C respectively suggesting the shallower sample is immature and the deeper one mature with respect to hydrocarbon generation (Fig 35b). Most samples in the Punchaw well contain Type HI kerogen (Fig. 35c and g). Two samples may contain Type I (Fig. 35g) or Type II kerogen (Fig. 35c). Based on the S2/S3 ratio all samples but one are of Type III (Table 8). HI values for samples with source rock potential (620 and 3390 m) indicate they contain type II (oil and gas prone) kerogen. However, the S2/S3 ratios suggest type III (gas prone) kerogen. (vi) OUTCROP SAMPLES FROM THE CHILCOTIN-NECHAKO REGION Ninety nine percent of analyzed outcrop samples have poor hydrocarbon potential, as evident from low QOM ( < 1.4 mg HC/g orgC) and HCP ( < 2 mg HC/g rock) values (Table 19; Fig. 36). Samples with good TOC values occur in a number of areas; however these locations do not have corresponding high HCP or QOM values (Figs. 36b and c) and therefore have poor hydrocarbon potential. Figure 36a shows the lateral distribution of TOC values for outcrop samples within the Chilcotin-Nechako region. The remaining one percent of outcrop samples (J89-067-02, J89-106-03, J89050-01, J89-DFWD and J89-282-11) have moderate to good source potential. However, these samples represent beds within individual outcrops and thus, may not be regionally representitive. Sample J89-067-02, taken from a 1 m thick, fine grained sandstone bed on Bill Nye Lake Road in the Morice Lake area (App. A),  203  Table 19 Summary of Rock-Eval pyrolysis results for outcrop samples from the  Chilcotin-Nechako Region. (0 = no measurement)  204  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # J89-004-02 J89-004-03 J89-004-04 J89-005-01 J89-005-02 J89-005-05 J89-005-07 J89-005-07 J89-005-08 J89-005-10 J89-005-10 J89-006-02 J89-006-02 J89-006-05 J89-006-06 J89-006-07 J89-006-07A J89-006-11 J89-006-14 J89-006-15 J89-006-16 J89-006-16 J89-006-19 J89-006-21 J89-006-22 389-007-01 389-007-02 389-007-04 389-007-05 389-007-06 J89-007-07 389-007-08 389-007-09 J89-007-10 J89-007-11 389-007-12 389-007-13 389-007-14 J89-007-15 389-007-16 389-007-17 389-007-18 J89-007-19 389-007-20 389-007-21 J89-007-22 389-007-23 389-007-24  TMAX  TOC  0 0 0 0 397 0 0 0 0 0 0 0 0 446 0 0 0 323 0 317 0 0 0 0 0 465 452 468 491 450 472 457 481 448 446 458 453 465 461 516 459 471 452 448 494 449 459 479  0.07 0.00 0.34 0.02 0.02 0.44 0.07 0.05 0.02 0.01 0.05 0.19 0.12 1.33 0.51 0.47 0.33 0.12 0.13 0.10 0.16 0.21 0.04 0.02 0.18 0.68 0.74 0.69 0.83 0.79 2.79 0.85 0.93 0.89 1.17 1.11 1.03 1.38 1.67 4.32 1.52 1.34 0.59 1.75 0.55 2.03 1.75 1.45  HCP  QOM  HI  PI  0.01 0.14 0.00 ******* 0.00 0.00 0.00 0.00 0.02 1.00 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.02 0.06 0.04 0.33 0.01 0.08 0.01 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.23 0.34 0.24 0.32 0.20 0.29 0.12 0.14 0.33 0.26 0.39 1.08 0.35 0.41 0.34 0.37 0.36 0.32 0.49 0.42 0.45 0.50 0.33 0.34 0.59 0.43 0.34 0.57 0.06 0.27 0.20 0.31 0.13 0.18 0.12 0.20 0.29 0.51 0.40 0.22 0.24 0.48 0.16 0.28 0.22 0.15  14 0 0 0 100 2 0 0 0 0 0 0 0 1 0 0 6 33 0 10 0 0 0 0 0 32 31 27 14 32 35 40 35 34 40 44 32 39 32 5 19 12 20 26 38 23 16 15  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.04 0.05 0.00 0.00 0.09 0.03 0.03 0.03 0.04 0.02 0.03 0.07 0.04 0.08 0.03 0.06 0.00 0.10 0.05 0.02 0.00 0.00  S2,0.00 0.00 0.00 0.00 2.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 0.00 0.00 1.00 2.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.47 0.62 0.31 0.21 0.55  1.25 1.13 0.86 0.81 1.27 1.06 1.03 1.77 1.57 0.86 0.35 0.29 0.09 0.80 0.30 0.65 0.44 0.44  205  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # 389-007-25 389-007-26 389-007-27 389-007-28 389-008-01 J89-008-02 389-008-03 389-008-04 389-008-06 389-008-07 J89-008-08 389-008-09 389-009-02 J89-011-01 389-014-01 J89-014-05 J89-014-08 J89-016-01 389-017-01 389-017-02 389-017-03 389-017-04 389-018-01 389-018-02 389-018-03 J89-020-01 J89-021-01 J89-022-01 389-023-01 389-025-01 389-026-01 389-030-01 J89-030-03 389-032-01 J89-034-01 389-036-01 389-037-03 389-037-04 389-037-05 389-038-01 J89-040-01 J89-046-01 J89-049-01 389-050-01 389-050-03 389-051-01 J89-054-01 J89-055-01  TMAX  TOC  HCP  QOM  HI  PI  S2/S3  405 475 452 490 466 453 452 446 451 456 460 448 0 423 450 474 476 337 0 483 483 0 446 0 0 0 448 0 528 518 524 519 531 0 0 0 441 464 0 471 0 0 501 505 0 341 332 0  0.39 0.82 1.24 0.42 2.57 1.63 1.20 1.37 1.45 1.57 0.66 1.65 0.14 0.17 1.01 1.15 1.40 0.09 0.02 1.02 0.42 0.06 0.16 0.01 0.07 0.04 0.03 0.07 0.43 0.69 1.14 1.27 2.57 0.17 0.57 0.21 13.11 0.84 0.23 67.79 0.10 0.11 0.59 2.05 0.12 0.08 0.19 1.39  0.09 0.27 0.33 0.14 1.41 0.61 0.72 0.79 0.85 0.63 0.21 0.83 0.00 0.03 0.46 0.22 0.46 0.07 0.01 0.30 0.12 0.00 0.02 0.00 0.00 0.12 0.01 0.01 0.06 0.11 0.12 0.21 0.28 0.01 0.00 0.00 6.80 0.13 0.00 27.29 0.00 0.00 0.06 5.14 0.00 0.03 0.05 0.00  0.23 0.33 0.27 0.33 0.55 0.37 0.60 0.58 0.59 0.40 0.32 0.50 0.00 0.18 0.46 0.19 0.33 0.78 0.50 0.29 0.29 0.00 0.12 0.00 0.00  23 30 26 30 49 34 57 52 55 37 30 44 0 11 42 17 32 77 50 25 23 0 12 0 0  0.00 0.08 0.00 0.07 0.10 0.07 0.04 0.09 0.06 0.06 0.05 0.12 0.00 0.50 0.07 0.09 0.02 0.00 0.00 0.13 0.17 0.00 0.00 0.00 0.00  0.33 0.14 0.14 0.16 0.11 0.17 0.11 0.06 0.00 0.00 0.52 0.15 0.00 0.40 0.00 0.00 0.10 2.51 0.00 0.38 0.26 0.00  33 0 11 14 9 14 10 0 0 0 51 15 0 39 0 0 10 212 0 37 26 0  0.47 1.25 0.56 0.20 3.09 0.60 5.30 1.60 7.27 1.78 0.76 0.75 0.00 2.00 4.77 1.11 2.25 0.53 0.08 3.25 1.25 0.00 0.11 0.00 0.00 0.00  3.00  0  1.00 0.00  0.00 0.17 0.10 0.08 0.10 0.04 0.00 0.00 0.00 0.01 0.0C 0.00 0.02 0.00 0.00 0.00 0.15 0.00 0.00 0.00 0.00  0.05  0.00 5.00 0.55 0.52 1.00 0.61 0.00 0.00 0.00 1.25 0.40 0.00 0.81 0.00 0.00 0.66 0.00 0.00 0.16 0.15 0.00  206  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # J89-057-01 J89-057-02 J89-057-03 J89-060-02 J89-062-01 J89-063-02 J89-063-03 J89-064-01 J89-064-02 J89-067-02 J89-068-01 J89-069-01 J89-070-02 J89-072-01 J89-077-01 J89-077-04 J89-080-01 J89-082-01 J89-082-02 J89-085-01 J89-086-02 J89-087-01 J89-088-01 J89-096-01 J89-096-02 J89-098-03 J89-100-01 J89-106-02 J89-106-03 J89-106-19 J89-120-01 J89-120-02 J89-121-01 J89-127-02 J89-127-04 J89-128-02 J89-128-03 J89-128-04 J89-128-05 J89-128-06 J89-128-06 J89-132-02 J89-132-03 J89-135-01 J89-139-01 J89-143-01 J89-143-02 J89-161-01  TMAX  TOC  HCP  QOM  HI  PI  S2/S3  0 0 0 0 0 0 0 0 0 438 0 0 451 463 0 0 0 0 0 0 0 0 0 439 441 445 498 0 473 442 0 0 0 0 0 0 0 0 0 0 0 303 0 0 0 0 0 0  0.00 0.02 0.00 0.05 0.33 0.53 0.33 0.21 0.05 1.17 0.10 0.14 0.19 0.87 0.51 0.03 0.71 0.04 0.09 0.12 0.30 0.07 0.25 0.16 0.18 0.49 0.43 0.00 1.04 0.39 0.14 0.00 0.31 49.67 0.16 1.54 0.04 0.28 0.56 0.06 0.18 0.02 0.38 0.01 0.00 0.00 0.18 0.02  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.28 0.00 0.00 0.05 0.46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.17 0.15 0.16 0.08 0.01 2.22 0.56 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.01 0.00 0.03 0.00 0.00 0.00 0.01 0.00 0.00  ******* 0.00 ******* 0.00 0.00 0.00 0.00 0.00 0.00 1.95 0.00 0.00 0.26 0.53 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.06 0.83 0.33 0.19 ******* 2.13 1.44 0.07 ******* 0.00 0.00 0.00 0.00 0.00 0.14 0.00 0.17 0.00 1.50 0.00 0.00 ******* ******* 0.00 0.00  0 0 0 0 0 0 0 0 0 176 0 0 26 44 0 0 0 0 0 0 0 0 0 87 77 32 18 0 210 128 0 0 0 0 0 0 0 0 0 0 0 150 0 0 0 0 0 0  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.09 0.00 0.00 0.00 0.15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.19 0.07 0.00 0.00 0.00 0.01 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 20.70 0.00 0.00 0.00 4.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.63 3.50 0.59 8.00 0.00 12.88 2.38 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.21 0.00 0.00 0.00 0.00 0.00 0.00  207  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION  SAMPLE # J89-163-01 J89-163-02 J89-164-01 J89-164-02 J89-165-01 J89-167-01 J89-167-03 J89-172-01 J89-173-01 J89-185-01 J89-189-01 J89-189-02 J89-189-03A J89-189-05 J89-190-02 J89-190-03FL J89-191-03 J89-193-01 J89-193-03B J89-193-03B J89-193-03C J89-193-05 J89-193-07 J89-193-08 J89-199-01 J89-199-02 J89-201-01 J89-201-02 J89-201-03 J89-204-01 J89-204-02 J89-204-03 J89-205-02 J89-209-01 J89-218-01A J89-218-01B J89-219-01 J89-219-04 J89-220-01 J89-222-01 J89-222-02 J89-226-01 J89-230-02 J89-230-03 J89-230-04 J89-230-05 J89-230-06 J89-232-01  TmAx  TOC  HCP^QOM  HI  PI  S2/S3  379 478 506 483 0 0 444 428 0 0 0 0 345 0 0 0 449 0 0 0 0 0 568 0 0 0 0 0 0 303 0 0 0 0 0 332 0 0 0 0 0 0 0 0 0 0 0 436  0.14 0.35 0.56 0.00 0.00 0.00 3.28 0.01 0.05 0.00 0.00 0.05 0.10 0.00 0.00 0.02 0.00 0.12 0.00 0.00 0.00 0.01 1.03 0.00 0.26 0.00 0.00 0.03 0.07 0.00 0.00 0.00 0.00 0.03 0.14 0.95 0.20 0.44 0.16 0.00 0.01 0.02 0.03 0.25 0.04 0.05 0.13 55.13  0.05^0.36 0.20^0.57 0.16^0.29 0.04 ******* 0.00 ******* 0.00 ******* 0.09^0.03 0.04^4.00 0.01^0.20 0.00 ******* 0.00 ******* 0.02^0.40 0.11^1.10 0.00 ******* 0.01 ******* 0.00^0.00 0.03 ******* 0.03^0.25 0.00 ******* 0.00 ******* 0.01 ******* 0.00^0.00 0.02^0.02 0.00 ******* 0.01^0.04 0.04 ******* 0.00 ******* 0.01^0.33 0.08^1.14 0.01 ******* 0.00 ******* 0.00 ******* 0.00 ******* 0.01^0.33 0.00^0.00 0.01^0.01 0.01^0.05 0.02^0.05 0.00^0.00 0.03 ******* 0.03^3.00 0.00^0.00 0.01^0.33 0.00^0.00 0.00^0.00 0.00^0.00 0.01^0.08 9.01^0.16  35 57 26 0 0 0 2 400 0 0 0 20 70 0 0 0 0 25 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 33 0 0 0 0 15  0.00 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.50 0.40 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 1.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04  5.00 2.85 1.66 0.01 0.00 0.00 0.09 1.33 0.00 0.00 0.00 0.03 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.25 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.14 0.00 0.00 0.25 0.00 0.00 0.00 0.00 0.23  208  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # J89-232-02 J89-233-01 J89-233-01 J89-234-01 J89-235-01 J89-236-01 J89-236-02 J89-236-03B J89-236-04 J89-236-04B J89-236-05 J89-236-06 J89-236-07 J89-236-09 J89-236-CG J89-240-01 J89-240-02 J89-240-05A J89-240-05B J89-241-01 J89-241-02 J89-241-03 J89-243-02 J89-245-01 J89-245-04 J89-245-06 J89-247-01 J89-247-02 J89-248-01 J89-248-02 J89-248-03 J89-249-02 J89-249-03 J89-249-06 J89-249-07 J89-249-08 J89-249-09 J89-249-10 J89-251-01 J89-251-02 J89-251-02 J89-251-03 J89-252-01 J89-253-01 J89-254-01 J89-255-01 J89-258-01 J89-258-02  TMAX  TOC  HCP^QOM  HI  PI  S2/S3  423 0 0 406 0 446 0 303 343 0 0 0 0 0 0 0 0 0 0 325 0 0 0 0 541 0 303 303 0 0 0 0 0 0 475 451 495 480 0 0 0 0 362 0 0 0 447 437  22.43 0.00 0.00 6.07 0.17 0.00 0.14 0.33 0.31 0.17 0.43 0.08 0.13 0.00 0.00 0.38 0.36 0.00 0.26 1.13 0.26 0.14 0.20 0.14 1.13 0.00 0.23 0.14 0.20 0.04 1.16 0.06 0.01 0.01 0.01 1.16 0.61 0.47 0.02 0.19 0.15 0.08 0.08 0.00 0.00 0.00 0.24 0.11  21.12^0.94 0.00 ******* 0.00 ******* 3.36^0.55 0.00^0.00 0.03 ******* 0.00^0.00 0.03^0.09 0.07^0.23 0.00^0.00 0.00^0.00 0.00^0.00 0.00^0.00 0.00 ******* 0.00 ******* 0.00^0.00 0.01.^0.03 0.01 ******* 0.00^0.00 0.05^0.04 0.01^0.04 0.01^0.07 0.00^0.00 0.00^0.00 0.21^0.19 0.00 ******* 0.02^0.09 0.06^0.43 0.04^0.20 0.00^0.00 0.01^0.01 0.00^0.00 0.00^0.00 0.01^1.00 0.05^5.00 0.04^0.03 0.02^0.03 0.02^0.04 0.00^0.00 0.02^0.11 0.02^0.13 0.01^0.12 0.06^0.75 0.00 ******* 0.00 ******* 0.00 ******* 0.02^0.08 0.12^1.09  91 0 0 50 0 0 0 9 22 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 15 0 8 42 20 0 0 0 0 0 500 3 3 4 0 0 0 0 75 0 0 0 8 109  0.03 0.00 0.00 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  1.81 0.00 0.00 6.10 0.00 0.50 0.00 0.09 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.50 0.00 0.00 0.00 0.00 8.50 0.00 0.00 0.00 0.20 0.00 0.00 0.00 0.00 0.00 0.62 0.25 0.28 0.20 0.00 0.00 0.00 0.00 3.00 0.00 0.00 0.00 1.00 0.00  209 SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # 389-258-03 389-258-04 389-260-01 389-260-02 389-261-03 389-261-05 J89-261-05 389-261-06 389-261-07 389-262-01 389-263-01 389-264-01 389-265-01 389-266-01 389-269-02 389-269-N 389-271-01 389-271-02 389-272-01 389-273-01 389-274-04 389-276-01 389-276-02 389-278-FL 389-279-01 389-279-03 389-279-05 389-280-01 389-281-01 389-282-01 389-282-02 389-282-03 389-282-03 389-282-04 389-282-05 389-282-06 389-282-07 389-282-09 389-282-10 389-282-11 389-283-01 J89-284-01 J89-285-01 J89-285-02 389-285-03 389-285-04 389-285-05 J89-285-05  TMAX  TOC  HCP^QOM  HI  PI  S2/S3  440 446 430 492 0 0 0 0 302 466 488 465 496 449 0 352 411 0 0 0 0 308 0 0 518 472 490 0 0 499 0 493 499 451 0 505 466 484 474 481 469 489 0 0 0 0 453 0  0.93 2.33 0.22 0.58 0.08 0.45 0.45 0.07 0.03 1.59 0.52 54.81 55.19 1.14 0.43 0.57 0.30 0.13 0.12 0.00 0.06 0.04 0.01 0.17 33.29 0.34 0.26 0.08 0.05 6.22 0.09 0.58 1.93 0.35 0.16 2.04 17.18 3.24 2.24 5.90 1.07 1.63 0.05 0.03 0.37 0.00 39.63 0.03  0.36^0.39 0.84^0.36 0.02^0.09 0.05^0.09 0.00^0.00 0.01^0.02 0.01^0.02 0.03^0.43 0.02^0.67 0.43^0.27 0.08^0.15 31.08^0.57 3.13^0.06 0.16^0.14 0.00^0.00 0.10^0.18 0.11.^0.37 0.00^0.00 0.02^0.17 0.00 ******* 0.00^0.00 0.01^0.25 0.00^0.00 0.00^0.00 9.99^0.30 0.22^0.65 0.14^0.54 0.04^0.50 0.00^0.00 1.55^0.25 0.00^0.00 0.04^0.07 0.39^0.20 0.01^0.03 0.00^0.00 0.41^0.20 15.81^0.92 1.17^0.36 1.24^0.55 19.62^3.33 0.79^0.74 0.46^0.28 0.00^0.00 0.01^0.33 0.00^0.00 0.00 ******* 26.25^0.66 0.00^0.00  38 35 4 6 0 0 0 28 66 26 15 56 5 14 0 10 30 0 16 0 0 25 0 C 29 41 53 50 0 24 0 6 20 2 0 20 90 36 54 331 52 27 0 33 0 0 65 0  0.00 0.01 0.50 0.25 0.00 0.00 0.00 0.50 0.00 0.02 0.00 0.01 0.00 0.00 0.00 0.40 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.02 0.00 0.29 0.02 0.00 0.00 0.00 0.00 0.01 0.00  9.00 3.45 0.05 4.00 0.00 0.00 0.00 0.05 0.22 0.50 0.53 2.01 0.52 0.19 0.00 0.11 1.00 0.00 0.66 0.00 0.00 0.00 0.00 0.00 12.81 0.82 0.48 1.00 0.00 1.89 0.00 0.13 1.05 0.10 0.00 0.87 23.19 2.38 6.10 65.16 2.43 0.81 0.00 0.00 0.00 0.00 3.92 0.00  210  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # J89-286-02 J89-286-04 J89-286-07 J89-286-08 J89-286-10 J89-286-11 J89-DFWD J89-HBMTN  J89-KK  J89-WRB J90-001-01 J90-001-04 J90-002-01 J90-002-02 J90-003-01 J90-003-09 J90-005-01 J90-005-02 J90-006-01 J90-006-02 J90-006-03 J90-009-01 J90-009-03 J90-009-04 J90-009-05 J90-009-06 J90-009-07 J90-009-08 J90-009-09 J90-010-01 J90-010-02 J90-010-03 J90-010-04 J90-010-05 J90-011-06 J90-011-13 J90-011-15 J90-012-02 J90-012-04 J90-012-06 J90-012-09-C OAL J90-012-09-S S J90-012-14 J90-012-15 J90-012-16 J90-012-17  TMAX  TOC  HCP^QOM  HI  PI  S2/S3  328 447 417 0 0 363 426 0 500 0 372 0 433 446 0 449 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 462 349 0 0 0 0 580  0.59 0.27 0.08 0.63 0.13 0.95 1.35 15.79 1.43 0.00 0.22 0.05 0.21 0.23 0.50 0.31 0.02 0.31 0.03 0.10 0.44 0.06 0.00 0.17 0.12 0.06 0.30 0.28 0.11 0.00 0.00 0.05 0.02 0.01 0.71 0.95 0.43 0.44 0.55 0.00 14.42  0.04^0.07 0.04^0.15 0.12^1.50 0.01^0.02 0.04^0.31 0.09^0.09 2.71^2.01 0.00^0.00 0.51^0.36 0.00 ******* 0.13^0.59 0.00^0.00 0.21^1.00 0.16^0.70 0.00^0.00 0.01^0.03 0.00^0.00 0.00^0.00 0.00^0.00 0.01^0.10 0.00^0.00 0.02^0.33 0.04 ******* 0.14^0.82 0.01^0.08 0.01^0.17 0.00^0.00 0.02^0.07 0.01^0.09 0.00 ******* 0.00 ******* 0.00^0.00 0.01^0.50 0.00^0.00 0.07^0.10 0.02^0.02 0.00^0.00 0.01^0.02 0.00^0.00 0.00 ******* 1.00^0.07  3 3 100 0 30 7 187 0 32 0 36 0 90 65 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 2 0 0 0 0 6  0.50 0.75 0.33 0.00 0.00 0.25 0.07 0.00 0.10 0.00 0.42 0.00 0.10 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00  0.15 0.05 0.44 0.00 0.44 0.15 3.61 0.00 9.20 0.00 0.10 0.00 0.59 0.21 0.00 0.03 0.00 0.00  1.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.22 0.02 0.00 0.00 0.00 0.00 0.11  0  0.06  0.00^0.00  0  0.00  0.00  0 0 358 0  0.02 0.09 0.44 0.00  0.00^0.00 0.07^0.78 0.03^0.07 0.01 *******  0 44 6 0  0.00 0.50 0.00 0.00  0.00 0.06 0.13 0.00  0.75  A... ,;u 0.00 0.00 0.07  211  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # 390-012-18 390-012-19 390-012-20 390-012-21 390-012-22 390-012-23 390-012-24 390-012-24 390-012-27 390-012-28 390-012-29 390-012-30 390-014-01 390-014-02 390-014-04 390-014-05 390-014-06 390-014-07 390-014-08 390-014-09 390-014-10 390-014-11 390-014-12 390-014-13 390-014-13 390-014-14 390-014-16 390-014-17 390-014-18 390-014-19 390-014-20 390-014-21 390-014-22 390-014-23 390-014-25 390-014-26 390-014-27 390-014-27 390-014-28 390-014-29 390-014-30 390-014-31 390-014-32 390-014-33 390-014-34 390-014-35 390-014-36 390-014-37  TMAX  TOC  HCP^QOM  HI  PI  S2/S3  0 0 0 0 0 425 0 0 0 337 0 0 467 0 350 0 0 0 0 354 0 0 301 0 497 332 519 0 440 0 0 0 390 0 0 444 0 301 392 0 370 0 521 521 427 361 521 515  0.00 0.02 0.06 0.24 0.00 0.72 0.00 0.00 0.03 0.00 0.45 0.00 0.54 0.05 0.68 0.23 0.00 0.00 0.00 0.41 0.31 0.01 0.29 0.02 2.34 0.27 0.00 0.41 0.82 0.23 0.18 0.17 0.30 0.17 0.16 0.30 0.28 0.27 0.28 0.18 0.32 0.05 6.49 4.15 1.25 0.29 2.43 0.66  0.00 ******* 0.00^0.00 0.00^0.00 0.00^0.00 0.00 ******* 0.08^0.11 0.00 ******* 0.00 ******* 0.00^0.00 0.03 ******* 0.00^0.00 0.00 ******* 0.11^0.20 0.00^0.00 0.02^0.03 0.00^0.00 0.00 ******* 0.00 ******* 0.00 ******* 0.02^0.05 0.00^0.00 0.00^0.00 0.01^0.03 0.00^0.00 0.54^0.23 0.01^0.04 0.13 ******* 0.00^0.00 0.01^0.01 0.00^0.00 0.00^0.00 0.00^0.00 0.03^0.10 0.00^0.00 0.04^0.25 0.06^0.20 0.00^0.00 0.01^0.04 0.02^0.07 0.00^0.00 0.01^0.03 0.00^0.00 1.03^0.16 0.79^0.19 0.04^0.03 0.02^0.07 0.18^0.07 0.12^0.18  0 0 0 0 0 11 0 0 0 0 0 0 18 0 2 0 0 0 0 4 0 0 3 0 22 3 0 0 1 0 0 0 10 0 6 16 0 3 7 0 3 0 15 18 3 6 6 16  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.08 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.75 0.17 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.04 0.00 0.00 0.06 0.08  0.00 0.00 0.00 0.00 0.00 0.22 0.00 0.00 0.00 0.10 0.00 0.00 0.30 0.00 0.02 0.00 0.00 0.00 0.00 0.09 0.00 0.00 0.04 0.00 1.26 0.02 0.09 0.00 0.01 0.00 0.00 0.00 0.06 0.00 0.06 0.38 0.00 0.06 0.25 0.00 0.06 0.00 0.32 0.62 0.04 0.03 0.10 0.19  212 SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE #^TMAX^TOC^HCP^QOM^HI^PI S2/S3 J90-014-38 J90-014-39 390-014-40 J90-014-41 390-014-42 J90-014-43 390-014-44 390-014-45 390-014-45 390-014-46 390-014-47 390-014-48 390-014-49 390-014-50 390-014-51 J90-014-52 390-014-53 390-014-54 390-014-55 390-014-56 390-014-57 390-014-58 390-014-59 390-014-60 J90-014-61 390-014-62 390-014-63 390-014-64 390-014-65 390-014-66 390-014-67 390-014-68 390-014-69 390-014-70 390-014-71 390-014-72 J90-014-73 J90-014-74 390-014-75 J90-014-76 390-014-77 390-014-78 390-014-79 J90-014-80 390-014-81 390-014-82 390-014-83 390-014-84  0 0 325 0 301 301 437 0 0 334 378 343 344 447 0 0 0 351 0 0 0 0 359 0 365 0 0 0 0 0 0 0 356 451 361 431 0 356 480 476 0 348 436 439 0 515 493 516  0.24 0.22 0.21 0.23 0.22 0.18 0.30 0.05 0.25 0.26 0.31 0.26 0.28 0.23 0.20 0.26 0.24 0.30 0.31 0.18 0.25 0.33 0.32 0.27 0.24 0.25 0.30 0.00 0.27 0.20 0.19 0.26 0.16 0.23 0.23 0.38 0.00 0.24 0.40 0.33 0.20 0.29 0.27 0.25 0.03 0.62 1.99 0.58  0.00^0.00 0.00^0.00 0.01^0.05 0.00^0.00 0.01^0.05 0.01^0.06 0.04^0.13 0.00^0.00 0.01^0.04 0.02^0.08 0.01^0.03 0.01^0.04 0.02^0.07 0.01^0.04 0.00^0.00 0.00^0.00 0.00^0.00 0.02^0.07 0.00^0.00 0.00^0.00 0.00^0.00 0.00^0.00 0.01^0.03 0.00^0.00 0.01^0.04 0.00^0.00 0.00^0.00 0.00 ******* 0.00^0.00 0.00^0.00 0.01^0.05 0.00^0.00 0.03^0.19 0.01^0.04 0.01^0.04 0.06^0.16 0.00 ******* 0.03^0.12 0.13^0.33 0.06^0.18 0.00^0.00 0.04^0.14 0.07^0.26 0.05^0.20 0.00^0.00 0.09^0.15 0.64^0.32 0.06^0.10  0 0 4 0 4 5 13 0 4 7 3 3 7 4 0 0 0 6 0 0 0 0 3 0 4 0 0 0 0 0 5 0 12 4 4 13 0 8 25 18 0 13 22 20 0 14 31 10  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.50 0.00 0.00 0.17 0.00 0.50 0.25 0.00 0.00 0.00 0.17 0.00 0.00 0.00 0.02 0.00  0.00 0.00 0.08 0.00 0.09 0.06 0.21 0.00 0.04 0.06 0.03 0.07 0.09 0.05 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.03 0.00 0.09 0.00 0.00 0.00 0.00 0.00 0.12 0.00 0.22 0.07 0.07 0.29 0.00 0.14 0.20 0.54 0.00 0.28 0.30 0.31 0.00 0.64 1.18 0.19  213  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # J90-014-85 J90-014-86 J90-014-87 J90-014-88 J90-014-89 J90-014-90 J90-020-01 J90-020-02 J90-020-03 J90-020-04 J90-020-06 J90-021-01 J90-021-02 J90-021-03 J90-021-04 J90-022-02B J90-023-01 J90-023-07 J90-023-08 J90-025-02A J90-027-01 J90-027-02 J90-038-02B J90-038-03 J90-038-05A J90-038-05A J90-038-05A2 J90-038-05B J90-038-07A J90-038-07C J90-038-07D J90-038-09 J90-038-11 J90-038-12 J90-038-14 J90-038-16 J90-038-18 J90-038-20 J90-038-22 J90-039-03A J90-039-03B J90-039-05A J90-039-05B J90-039-05C J90-039-05D J90-039-07 J90-039-09 J90-039-11  TMAX  TOC  511 382 330 301 0 0 0 0 0 0 0 0 454 0 0 0 0 492 0 0 467 519 0 0 0 338 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 364 0 0 0  1.03 0.26 0.22 0.31 0.26 0.07 0.00 0.00 0.01 0.01 0.51 0.09 1.30 0.03 0.11 0.28 0.92 0.56 0.68 0.10 0.67 0.97 0.20 0.00 0.03 0.14 0.06 0.01 0.08 0.44 0.20 0.01 0.09 0.07 0.09 0.16 0.15 0.02 0.04 0.63 0.02 0.11 0.06 0.11 0.07 0.07 0.08 0.12  QOM  HI  PI  S2/S3  0.23 0.22 0.03 0.12 0.01 0.05 0.01 0.03 0.00 0.00 0.00 0.00 0.00 ******* 0.00 ******* 0.00 0.00 0.00 0.00 0.04 0.08 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.07 0.12 0.01 0.01 0.01 0.10 0.13 0.19 0.09 0.09 0.00 0.00 0.00 ******* 0.00 0.00 0.07 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.14 0.08 0.00 0.00 0.00 0.00 0.00 0.00  22 11 4 3 0 0 0 0 0 0 0 0 0 0 0 0 0 10 0 10 8 9 0 0 0 7 0 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 100 0 0 0  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.50 0.00 0.00 0.00 0.00 0.17 0.00 0.00 0.58 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.12 0.00 0.00 0.00  0.37 0.04 0.14 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.07 0.15 0.19 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.70 0.00 0.00 0.00  HCP  214  SUMMARY OF ROCK-EVAL RESULTS FOR OUTCROP SAMPLES IN THE CHILCOTIN-NECHAKO REGION SAMPLE # J90-039-15 J90-039-17A J90-039-18A J90-039-18B J90-039-20 J90-039-21 J90-039-22A J90-039-22B J90-039-25A J90-039-25B J90-039-29 J90-039-31 J90-039-31B J90-039-33 J90-039-36 J90-040-01B J90-FT-03 J90-FT-04 J90-FT-06 J90-FT-13 J90-FT-16 J90-FT-17A  TMAX  TOC  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 436 0 0 0 0 0 0  0.08 0.04 0.06 0.02 0.11 0.25 0.29 0.17 0.09 0.00 0.06 0.15 0.01 0.03 0.14 0.22 0.03 0.05 0.09 0.15 0.10 0.03  HCP  QOM  HI  PI  S2/S3  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ******* 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.45 0.10 0.01. 0.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 45 0 0 0 0 0 0  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00  215  Figure 36 Rock-Eval results for outcrop samples in the Chilcotin-Nechako Region  a) lateral distribution of total organic carbon content b) lateral distribution of the quality of organic matter c) lateral distribution of hydrocarbon potential  216  EGI N TOC VALUES Poor 0 — 0.5 Fair 0.5 — 1 Good 1 — 2 Very Good >2 (Small traingles and squares are data points )  50 30 10^50 km  217  C i i ILCOTIN - NECHAKO BF:GI N QOM VALUES Low <1.4  7  Moderate 1.4 — 3.0 High >3.0  (Small triangles and squares are data points)  5 4°  53  218  CHILC TIN - NECHAKO REGION HCP VALUES No oil source potential <2 Moderate source potential 2 — 6  Good source potential >6  530  219  has TOC, QOM and HCP values of 1.17, 1.95 and 2.28 respectively. Sample J89106-03, collected from a 0.8 m thick, very fine grained, carbonaceous sandstone near Francois Lake (App. A), has TOC, QOM and HCP values of 1.04, 2.13 and 2.22 respectively. J89-050-01, collected from a 0.6 m thick, carbonaceous, black mudstone near Meed Creek (App. A), has values of TOC (2.05), QOM (2.51) and HCP (5.14); and sample J89-DFWD, taken from a 1 m thick, medium grained sandstone bed on the Driftwood Creek Road, has TOC, QOM and HCP values of 1.35, 2.01 and 2.71 respectively indicating these four samples are moderate source rocks. Sample J89-282-11, collected from a 0.75 m thick highly carbonaceous bed in Houston Tommy Creek, has values of TOC (5.90), QOM (3.33) and HCP (19.62) values that suggest it has good source potential. Tmax and PI values for samples J89-67-2 and J89-DFWD suggest they are immature with respect to hydrocarbon generation (Tables 10 and 19). The values of the PI and Tmax for samples J89-50-1, J89-106-3 and J89-282-11 yield conflicting results. For samples 106-3 and 282-11 the Tmax values (473 and 481 ° C respectively) indicate the samples are overmature, however the PI values (0.01 and 0 respectively) suggest the samples are immature. The Tmax value (505°C) for sample 50-1 suggests it is overmature, the PI value (0.15) indicates it is mature. These conflicting results may be due to the effects of migration. Outcrop samples within the Chilcotin-Nechako region contain dominantly Type III kerogen (Fig 29 and Table 19). Most samples examined petrographically are composed of vitrinite with some inertinite, consistent with a Type III classification (plate 28). Of the five outcrop samples (J89-67-2, J89-50-1, J89-106-3, J89-282-11 and J89-DFWD) with source rock potential 282-11 has type I kerogen (HI= 331, S2/S3 = 65.16), DFWD has type II kerogen (HI = 187, S2/S3 = 3.61), 106-3 and 67-  220  Plate 28 - A combination of vitrinite and inertinite from outcrop samples. Reflected light, magnification x 512.  221  2 have type I or II kerogen (HI = 210, S2/S3 = 12.88; HI =176, S2/S3 = 20.70 respectively) and 50-1 has type II or III kerogen (HI =212, S2/S3 =0). D. DISCUSSION  1. MATURATION Organic maturation patterns are difficult to interpret laterally over any distance, especially where exposure is poor which in turn creates a low sample density. Thus it must be emphasized that the interpretations presented here are based on limited data and must be considered preliminary. An examination of the metamorphic map of the Canadian Cordillera (Read 1988) shows that Cretaceous sediments within the Chilcotin-Nechako region are mapped as subgreenscist facies (undivided or prehnite - pumpellyite). Metamorphic fades are correlatable with maturation values determined from vitrinite reflectance and the thermal alteration index (TM), as shown in table 20. Vitrinite reflectance data from this study (Table 12) indicate that most Cretaceous sediments exposed within the Chilcotin-Nechako region have zeolite grade metamorphism. Basal sediments of the Skeena Group (Hauterivian (?) to Albian (?) Kitsun Creek sediments) in northern Chilcotin-Nechako region are prehnite -pumpellyite to zeolite facies; overlying sediments of the Red Rose division are dominantly zeolite with rare prehnite -pumpellyite and unmetamorphosed facies (Tables 12 and 20 ). Albian to Cenomanian unnamed sediments of central Chilcotin-Nechako region and sediments of the Albian to Cenomanian Silverquick formation exposed in southern Chilcotin-Nechako region are zeolite or rarely prehnite -pumpellyite grade. Sediments of the middle Toarcian to Early Callovian Smithers Formation (Hazelton Group) and the Late Bajocian to Early Oxfordian Ashman Formation (Bowser Lake Group; Tipper and Richards, 1976) that underlie the Skeena Group  222  METAMORPHIC^COAL FACIES^RANK None  Zeolite  PrehnitePumpellyite  Table 20 -  Lignite  % Ro  TAI  < 0.38  < 2.25  0.38 - 1.5  2.25 - 3.5  1.5 - 4  3.5 - 4  Sub bituminous C to med. volatile bituminous Low volatile bituminous to meta anthracite  ^ Correlation of metamorphic facies with vitrinite reflectance and thermal alteration index (TAI) values (Read, 1988)  223  in northern Chilcotin-Nechako region, have prehnite -pumpellyite facies metamorphism (Tables 12 and 20 ). In southern Chilcotin-Nechako region Triassic sediments exposed near Farwell Canyon (Hickson, 1990) and Oxfordian to Barremian (Jeletzky and Tipper, 1968) sediments of the Relay Mountain Group are prehnite -pumpellyite and rarely upper zeolite facies. Tertiary sediments, including mid Paleocene sediments exposed in Thautil River (App. A) in northern ChilcotinNechako region and Eocene sediments exposed in Anahim Flats and the Fraser River canyon (near Gang Ranch, App. A) of southern Chilcotin-Nechako region have zeolite facies metamorphism. Thus, it would appear that within the Chilcotin-Nechako region outcrops of Mesozoic sediments older than mid Cretaceous are prehnite -pumpellyite, and mid to Late Cretaceous sediments are dominantly zeolite facies, as are younger, Early Tertiary sediments. TAI values, which can also be correlated with metamorphic grade (Table 20), were determined from well cuttings of the Nazko D-96-E and Chilcotin B-22-K wells (Table 13). These values indicate that the zeolite grade of metamorphism extends to depth. Most Late Albian to Cenomanian sediments within the Nazko well are zeolite grade with TM values ranging from 2.4-3.2; rare prehnite -pumpellyite grade and unmetamorphosed rocks occur at depths of 1365-1405 m and 977-998 m respectively (Table 13). Santonian to Maastrichtian sediments of the Chilcotin well (Table 5, Part I) have TM values of 1.5 - 2.75 suggesting they are unmetamorphosed or lower zeolite facies. Cenomanian (?) to Santonian volcanics, underlying sediments in the Chilcotin well, have TM values of 2.5 - 3.0 indicating zeolite grade metamorphism. TM values for mid Eocene sediments range from 1.0-2.25 indicating zeolite grade to unmetamorphosed rocks. Underlying Eocene (?) sediments yielded exceptionally high TM values of 3.5-4.0, possibly due to oxidation of organic matter. Mid Eocene volcanic rocks that overlie the mid Eocene  224  sediments have an average TM value of 1.75 suggesting they are unmetamorphosed; however, the basal 30 m of these volcanics have TM values of 3.5 to 4.0 (contact metamorphism of organic matter ?). Upper Eocene to Early Oligocene and overlying Early Miocene volcanic rocks yielded TM values of 1.0 and 0.25 respectively indicating they are unmetamorphosed. These new results have important repercussions on the view of the hydrocarbon potential of the Chilcotin-Nechako region. If the sediments are within the zeolite fades of metamorphism they are not overmature, but are immature to mature with respect to hydrocarbon generation, and may thus have significant potential. Within the Intermontane Belt, strata, correlative in part to mid to Late Cretaceous sediments in the Chilcotin-Nechako region, occur in northern British Columbia in the Bowser and Sustut basins and in the Tantalus Basin in Yukon Territory. Upper Barremian or Aptian to middle or Late Albian sediments of the McEvoy Formation, exposed in the Bowser Basin, yielded vitrinite reflectance values ranging from 1.7-3.5% (Bustin, 1984; Cookenboo and Bustin, 1989). Sediments of the Albian ( Lowey, 1984) Tantalus Formation have higher reflectance values ranging from 1.68-4.5% (Bustin, 1984; Hunt, 1989). These reflectance values are considerably higher than those yielded by strata of the correlative Skeena and Battlement Ridge groups exposed in the Chilcotin-Nechako region, which have Ro values of 0.51-2.61% and 0.8-1.75% respectively. Late Cretaceous sediments of the Tango Creek (Cenomanian - Turonian ?) and Brothers Peak (Campanian to Maastrichtian) formations (Bustin and McKenzie, 1989) exposed in the Sustut Basin yielded vitrinite reflectance values of 1.5-2.5% and 0.99-1.70% respectively. These values represent a higher level of maturation than that of older, Albian to Cenomanian, sediments in the Chilcotin-  225  Nechako region, and a much higher level than that of correlative sediments in the Chilcotin B-22-K well which are zeolite facies to unmetamorphosed. It is well documented that the degree of organic maturation is related to the thermal history of the strata and, that depth of burial and heat flow are two main factors affecting thermal history (Lopatin, 1971; Waples, 1980; Bustin, 1984 and many others). If the vitrinite reflectance values for Albian to Cenomanian sediments within the Intermontane Belt are examined together, it appears that there is a progressive decrease in maturation level southwards - from the highest reflectance values of 1.68-4.5% in the Tantalus Formation to the lowest values of 0.8-1.75 yielded by the Silverquick formation. This progression may reflect a trend of decreasing heatflow from north to south. Using maturation modelling techniques Bustin (1984) showed that the Bowser Basin has anomalously high heat flow: 45-75°C/km compared to a normal gradient of 25-30°C/km. Bustin (1984) suggests the high heat flow may be related to plutonism and underplating accompanying collision of the Stikine terrane with the Early Mesozoic margin of North America and/or a result of easterly directed subduction below the Coast Plutonic Belt. Similar high heat flow values (minimum of 44 ° C/km) in the Tantalus Basin, at least in the Whitehorse area, may be due to intrusion of the Whitehorse and Mount Mcintyre plutons (116-97 Ma; Hunt, 1989). There is probably lower heat flow in the southern Chilcotin-Nechako region than in the Bowser and Tantalus basins because basal sediments of the Silverquick formation that have been buried by about 3000 m of strata, the same as that of sediments in the Bowser and Tantalus basins, yielded vitrinite reflectance values about half the value of those found in the McEvoy and Tantalus formations (0.81.75% versus 1.75-3.5% and 1.68-4.5%). If the heat flow were as high as that in the Bowser and Tantalus basins then these reflectance values should be as high as those yielded by the McEvoy and Tantalus formations. Vitrinite reflectance values in the  226  central and northern Chilcotin-Nechako region are slightly higher than those in the southern part (Table 14), but are still considerably lower than those of the Bowser and Tantalus basins. However, it is difficult to determine the burial history of sediments in the Chilcotin-Nechako region because they are overlain dominantly by volcanic rocks whose thickness is laterally variable ( thickest closest to vents and thinning away from the vents). Lower vitrinite reflectance values in the Chilcotin-Nechako region may be due to less plutonic activity. An examination of the distribution of plutonic suites in the Canadian Cordillera shows that, following the deposition of Albian to Cenomanian sediments, plutonism occurred only in the northern and north-central parts of the Chilcotin-Nechako region (Woodsworth et al., 1982). The Bulkley intrusions were emplaced, in the Late Cretaceous, in the northern ChilcotinNechako region between the Lakes district and the Smithers area. In the Early Tertiary the Nanika, Babine, Goosly and Quanchus intrusive suites were emplaced in the northern and north-central parts of the Chilcotin-Nechako region. Because plutonic activity in the Chilcotin-Nechako region was concentrated in the northern and north-central parts, this may explain why the maturation levels in the Skeena Group and to some extent the unnamed sediments are higher than those of the Silverquick formation. (Due to difficulty in determining burial history for the Silverquick formation it is possible that the lower reflectance values are due to lower burial depths (minimum 2000 m) and not lower heat flow). 2. SOURCE ROCK POTENTIAL From the above results it is clear that there is limited hydrocarbon potential in the Chilcotin-Nechako region. Most strata sampled do not contain enough organic material to be considered source rocks; those samples that do contain sufficient carbonaceous material often have a low quality of organic matter (QOM)  227  and thus the wrong type of kerogen to produce liquid hydrocarbons. However, there are various horizons within the wells and a number of exposed areas (outcrop samples) that do have moderate to good hydrocarbon potential as summarized below. E. SUMMARY AND CONCLUSIONS  A. New data suggest that Mid to Late Cretaceous sediments exposed throughout the Chilcotin-Nechako region have zeolite grade metamorphism. This has important implications for the hydrocarbon sorce potential of the region because sediments with zeolite grade metamorphism have the potential to be within the oil window. Areas with sedimentary strata within the oil window include: Churn and Alexis Creeks; along the Taseko and Chilcotin Rivers; south of Nazko on the Honolulu Road; near Mount Waddington; between Francois and Ootsa Lakes; north of Francois Lake; the Morice Lake-Thautil River area; Houston Tommy Creek and the Bulkley Valley-Zymoetz River area. This lower than expected grade of metamorphism, in mid to Late Cretaceous sediments, is probably due to lower heat flow in the Chilcotin-Nechako region. Lower heat flow may be due to minimal plutonic activity in this region. Plutonic activity that did occur was concentrated in the north and north-central parts of the Chilcotin-Nechako region and may explain the slight increase in maturation values in these areas (Skeena Group and unnamed sediments). B. Rock-Eval pyrolysis data for outcrop samples and well cutiings from five wells within the Chilcotin-Nechako region indicate that most Cretaceous sedimentary strata have little hydrocarbon potential due to low organic matter content or poor quality of organic matter. Exceptions do occur at various depths  228  within the wells and five locations within the Chilcotin-Nechako region (Fig. 36); results are summarised below. (i) The TOC content of most strata within the Nazko D-96-E well is low ( < 0.5) as is the QOM ( < 1.4) indicating poor hydrocarbon potential. Exceptions to this can be found at depths of 360, 687.5, 707.5, 842.5 and 852.5 m where moderate source rocks occur (QOM 1.63 - 3.01; TOC 1- 1.37; HCP 1.05 - 3.19). (ii) Hydrocarbon source potential for strata within the Chilcotin B-22-K well is poor due to low TOC values ( < 0.5 wt %). However, moderate to good source rock occurs at a depth of 147.5 m (QOM 2.03; HCP 9.38; TOC 4.63). (iii) Strata within the Redstone D-94-G well have fair to very good TOC values; however, hydrocarbon potential is poor due to low QOM values ( < 1.4 mgHC/g orgC). Samples with moderate source rock potential occur at depths of 410 and 1030 m (QOM 1.22, HCP 2.29, TOC 1.88; QOM 1.45, HCP 3.66, TOC 2.53). (iv) Strata within the Redstone B-82-C well have poor to very good TOC values. However, most samples have low QOM and HCP values and are therefore poor source rocks. Exceptions to this occur in the depth interval from 1370 to 1412 m where good source rocks occur (QOM 2.97-4.42; TOC 1.85-2.84; HCP 5.4912.55). (v) TOC values for strata within the Punchaw well range from fair to very good, however most samples have low HCP and QOM values. Two samples from depths of 620 and 3390 m have moderate source rock potential (QOM 5.3, HCP 4.56, TOC 0.86; QOM 2.26, HCP 3.43, TOC 1.52). (vi) Outcrop samples within the Chilcotin-Nechako region generally have low hydrocarbon potential due to low TOC, QOM and HCP values. Exceptions to this do occur in five areas of the northern Chilkotin-Nechako region: Morice River,  229  Francois Lake, Houston Tommy Creek, Driftwood Creek and Meed Creek as shown in figure 36. C. The organic matter within all sediments examined is dominantly Type III with minor amounts of Type I and II. Organic matter within outcrop samples is dominantly composed of a combination of vitrinite and inertinite.  230  F. REFERENCES Bustin, R.M. 1984. Coalification levels and their significance in the Groundhog Coalfield, north-central British Columbia. International Journal of Coal Geology, 4, p 21-44. Bustin, R.M. and McKenzie, K.J. 1989. Stratigraphy and depositional environments of the Sustut Group, southern Sustut Basin, north central British Columbia. Bulletin of Canadian Petroleum Geology, vol. 37, #2, p 210-223. Cookenboo, H.O. and Bustin, R.M. 1989. Jura-Cretaceous (Oxfordian to Cenomanian) stratigraphy of the north-central Bowser Basin, northern British Columbia. Canadian Journal of Earth Sciences, vol. 26, #5, p 1001-1012. Dow, W.G. 1977. Kerogen studies and geologic interpretations. Journal of Geochemical Exploration, 7, p 79-99. England, T.D.J. and Bustin, R.M. 1986. Thermal maturation of the Western Canadian Sedimentary Basin south of the Red Deer River: 1). Alberta Plains. Bulletin of Canadian Petroleum Geology, v 34, p 71-90. Espitalie, J., Deroo, G. and Marquis, F. 1985. Rock-Eval pyrolysis and its applications. Institut Francais du Petrole, reprint 27299, 132p. Espitalie, R., Madec, M. and Tissot, B. 1977. Source rock characterisation method for petroleum exploration. 9th Annual Offshore Technology conference, Houston Texas, p 439-444. Hickson, CJ., (in press 1992). An update on the Chilcotin-Nechako Project and mapping in Taseko Lakes (920) area, west-central, British Columbia. Current Research, Part A, Geological Survey of Canada, Paper 92-1A. Hunt, JA. 1989. Thermal maturation and source rock potential of the Tantalus Formation, Whitehorse area, southern Yukon Territory, 51 p. Jeletzky, JA. and Tipper, H.W. 1968. Upper Jurassic and Cretaceous rocks of Taseko Lakes map-area and their bearing on the geological history of southwestern British Columbia. Geological Survey of Canada Paper 67-54, 218 p. Lopatin, N.V. 1971. Temperature and geologic time as factors in coalification: Izvestiya Akademii Nauk USSR, Seriya Geologicheskaya, vol. 3, p. 95-106. Lowey, G.W. 1984. The stratigraphy and sedimentology of siliciclastic rocks, west central Yukon, and their tectonic implications. Ph. D. Thesis, University of Calgary, Alberta, 620 p. Peters, K.E. 1986. Guidelines for evaluating petroleum source rock using programmed pyrolysis. American Association of Petroleum Geologists Bulletin, v 70, #3, p 318-329. Read, P.B. 1988. Metamorphic map of the Canadian Cordillera. Geological Survey of Canada Open File 1893. Tipper, H.W. and Richards, TA. 1976. Jurassic stratigraphy and history of north-central British Columbia. Geological Survey of Canada Bulletin 270, 73 p.  231 Tissot, B.P., Durand, B., Espitalie, J. and Combaz, A. 1974. Influence of nature and diagenesis of organic matter in formation of petroleum. American Association of Petroleum Geologists Bulletin, v58, p 499-506. Tissot, B.P. and Welte, D.H. 1984. Petroleum formation and occurrence. Second edition, SpringerVerlag, 699p. Waples, D. 1980. Organic geochemistry for exploration geologists. Burgess, New York, 141 p. Woodsworth, G.J., Anderson, R.G., Brookfield, A. and Tercier, P. 1988. Distribution of Proterozoic to Miocene plutonic suites in the Canadian Cordillera. Geological Survey of Canada Open File 1982.  232  APPENDIX A LOCATION MAPS  233  1989^1990 ^0^1:1 Stations only Stations with samples^  •^•  Samples not shown on following maps: Sample #  Map Sheet  Latitude  Longitude  J89-096-01 J89-145-01 J89-158-01 J89-159-01 J89-160-01  93K/4 93K/5 93G/4 93G/5 93G/5  54°04'N 54°22'N 53°19'N 53°22'N 53°01'N  125°51'W 125°52'W 123°56'W 123°57'W 123°38'W  ^  234  0 0  63 61^• \  53°00' N  .  6#4frofott°14^..b...5^545658 249 v 51.,, 54 ■ /*-^\^ 5t ... •46 .^. ...^/ b42 - - - - 259^260^. 1 ,^ ■ \ 48 /-'-`. "' ^  ^\  •51  s  REISET  6  CK.  24  HUDSON SAY MOUNTAIN  36  V  1611,•17  SMITHERS  /  93  L/14  93 L/ I I  -—— _ TELKWA  V 8  A  CK  34° 30' N  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet : 93 L / I I , 14 Scale I 250,000  Comments Fig. No.  A-►  235 3i , -8 r -0, ,^35.  81 0,00 i  -I-  -- -  00 . N  , ,^—^,-... 42 \^\  -...  ■)  glow rt  ASHMAN  2E6* /---285• RIDGE  Ci'  s\  \\  11•  _ .... ,^'  1.01°E  TZ  • -,  12^•'---, 13^,  \ ,.......„,..^.....----...„  ■  ■ IMP  93 L /13  ab C.  93 L/ 12  + l-  1-  c"  er. -a.  3,  1-  ca  0.• LI,  t..4  'g ''A •  l -  104  611  et. ,`  .00  fil 12  ..0-  +  +  ROCK^SAMPLE / STAT ION^LOCATION ^MAP NTS MOP Sheet :^93 L /^12,^13 Scale^: 1 : 250,000  1^Comments : Fig.^No.^A -7-  54°30' N  236 0  0  -  0 A  0  2, 95°00 N .  l  0 c.^ 35  041,04y4,  N  C K.  0  41e4e.^34 / •^•^33Q, 269^c4.,,, 39 32  $3 L/15 93 L/ 10  DOME MOUNTAIN  A • / 24$  ROCK SAMPLE / STATION LOCATION MAP Comments: NTS Map Sheet : 93 L/ 10,15 Fig. No. Scale o I: 250,000  A-a  ^  237 3t  ^4  ° 54° 30' N  DE N YS  265 264 266: 6263 267E? •262 268  Q  271  ti 204 CK  c %. 152  \•-- --' 73^72k,,,i, " -• -4^(153)^71 69 68^  ■ I  4t^ o  •  64 _ \  27^j/ • \ 65^ — — t•  26 ) -- `4? 24 -..^••-• McIIRIDE  L^  .1,  ti23 LAKE^1  .22  21 41 1 I 20 t_ ± 34* N  ^  ROCK SAMPLE/ STATION LOCATION MAP NTS Map Sheet : 93 L / 3, 6 Scale :^I: 250,000  Comments : Fig. No.^A- 4  ^ ^  238  * 54° ^`14I O  '?  es  c r  7k  r gy,  / A HOUSTON  ^256 ^-  • 255^- -  253^,1 257^254^,-r  i^,^ca.- 1 . .^ l -,..^% -  ^\^\ ks  (^\  I  I \\^ \ \ \^  / I  I  ) \\^ ( I^ \  //  /  /1^  1  I  ) *30  \  I •261^/ / I I  ......, •"'  ■ ."-- \ ■  1 \  --  .......  I^93 L / 7  1^!3  ^/ 2  I  It^ 48, ) /^  ■  (^  \-  I momiCg^ ,--- N.^N.,^  f  \  \ I /  t^  f  \  ■\  .... _^_... ,.. ..."^ \^ \ \ ..  \  \  N.  0 \ 4_^\ 0.^\ .2.^\  .i  PARROT  \^ 4095  t  N  LAKES  NO 9 4^ \  276^ 1 1istpst \ 2754: AP4AomA^1093 MOUNTAIN^ 274^ OWEN ,277^il 92 *278 LAKE^\ SI  ,  C.90 -  1 /  54° oo' N  ROCK SAMPLE / STATION LOCATION^MAP NTS Map Sheet : 93 L / 2, 7 Scale^:^I 1 250,000  Comments : Fig. No.^q  -  5  ■  239 3 ^Perow^ 0 les o • -  ^— ^—  3  "0 0 o  ^ ^  ea  TOPLEY^  fo ca  54° 30' N  "Ohs.  11.). Orik1p," '1/4#411  6  &ILKLEY LAKE ^  1  IMP  "411L  °  or  \\  II  \^.... •••• ... --.  \ \  \ 113 L / $^\ ■  113^L /^1^1 ( —, 's.  \  )  G00.2.Y LA/fE  PARROT LAKES  144 0  \\\ ^147  Colleymount  ^146  LI ..:. .. ...„-= — — — 0— ..^.... ..^.......^ .^  C lemretta .... _...,  -^FRANCOIS LAKE  .^-^•^.  ....^54° 00' N  ROCK SAMPLE / STATION LOCATION^MAP NTS Map Sheet :^93 L / I , 8 Scale^I :^: 250,000  •  Comments Fig. No.^A  -6  240 I  T  N  3  3I  -o in o a N  "O o1 vt NI  cy  /4, ,,,f_  0  .414,405,  mive# '`IllfilOak. _. __. ■ 114._ _Q.155  --^156  1  157 -- -Q1-__  93 G / 5 93 F/ 8 93 F/ I  1414;',,,-.  93 G / 4  RIVER  ',LAC%  -Alt  ... ... 169  1 0 1 sO  f-  EuC"  ......__-•  e '  ---  ..... .  .  .  .  .•••• ...  .  .  i  /  170  --  --  ' .  ..  -  . %  ..-  . \  171 \^ N. _ - 0- - .1.-- ....  172 -^ ... ..!  ±i^53 ° 00' N  +  I  ROCK  SAMPLE / STATION  NTS Map Sheet : 93 F / 1, 8 Scale : 1:250,000  LOCATION^MAP  Comments : Fig. No.^A  --#  _.  241  ,^54°00' N  1 4, 11 6 Q.,^•AiDanskin^_ _ i - - - \___ 1  ......_  /— ^.."---^1 ...1 ) \,_____e• -6-0 Grassy 118 f  f  Plains N..  \, 117  •  -Om 114 .y1113  136  35 10 134  1 121 120 122 j^• 119 123 ;114 131 125 1 93 E/I6  126..  93 F/ I  93 E/ 9  C HEs  L4TT A  0 0  0 in  0 CO  N  N  N  -4-  ROCK SAMPLE / STATION LOCATION MAP N TS Map Sheet : 93 F / 12 ,I3  Comments  Scale : 1:250,000  Fig. No.^A-  53°30' N  242  54°00'  N  ,  150^1489-- •-.. 1543■—.1.9 *^-,  ■  78•  .77 .79 0 0 o ,t) N  FR A NCOIS^LAKE  -0 e" lo N  1 _..^, — ... ^  1  ■-, \, 1 ?,  t  143 Q142 1410•,. r.^137 • _ ,........,^....... 1  .  140 139•^9' r^138 -  •  ,Wistaria )—,  oo rs  N  4 4 of.z.  . ...-, . .^ .. '^• \ ■ . \  •  93 E/ 15  +  93 E/ 16  .  1  + _____  TWEEDSMIUR  PARK  411  00(" IIIMempw•  .. ilk  .44  53° 30' N  +  4—  ROCK^SAMPLE / STATION LOCATION ^MAP NTS Map Sheet ;^93 E / 15,16 Scale I^I: 250,00Q  Comments: Fig. No.^A-41  243  54°00' N  0  f■  /  ■  9  —  0  G GE \ •^—^  SMOLA PEAK  ;'t4  A  1  93 E /14 93 E/11  SW/NG PEAlf  ao. 0! or , II a 82 %e VW.^eg  a^  t^84  a  \  86  s  x  yP  ('  14  53° 30' N  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet : 93 E /11, 14  Comments'  Scale^1: 250,000  Fig. No.^A-10  ^  244  53°00' N  /^ 164 4 163 \  \  / /^ /^ ,'---, ) \,,, , /^ .  3 0  3  \  O  0 ,o^\ ^\VI?. .'-'^ N z^ /^  A  kl-^ 168 F/Si/POT 4/^ .4, il .0,., V LAKE  ^167^  ^\  ^\  aR1  1 \N^\ \.%)^ ,\ VP  ^... "... '  8^ \^MICHELLE trail RD.^  II 161  2' 2 \%1 L0 ,1-..6-!  \ k "  N  \ .\  \  .9  I-/  it` 9  93 9/13 93 B/12  ` 4 'sgAuro  NAZKO afrALLS  RIVER  52°30' N  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet : 93 13/12, 13 Scale : I: 250,000  Comments : Fig. No.^R  245  ROCK^SAMPLE / STATION LOCATION NTS Map Sheet :^93 B/ 11,14 Scale ;^I: 250,000  Comments Fig. No.  MAP  A-12  246  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet : 93 B/4,5 Scale : I: 250,000  Comments: Fig. No.  A-is  247  HI_  ^  0  00  N  N  183 0/  o  181  61180  ALEXIS CREEK  • 200  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet : 93 B/ 3,6 Scale^I 250,000  Comments Fig. No.^A-I4  52°30' N  248 52°30' N  0  PI  0 0J  93 0/9 93 5/I  WILLIAMS LAKE  52°00' N  ROCK^SAMPLE / STATION LOCATION NTS Map Sheet : 93 8/ 1,8 Scale^:^1 : 250,000  Comments Fig. No.  MAP  A-15  249  PUNTZ1 LAKE  ROCK^SAMPLE^LOCATION NTS MAP SHEET: 93 C/1,8  COMMENTS:  SCALE : 1: 250,000  FIG. NO.:  MAP P-16  ■  250 •  0 0  0  52°00' N  205 •  202  • 204  203 HWY. 20  VILLE.  0225 226  227 0\ I\^  231  0  ‘ 229 0228 , 0 '*230 \-1\ RIVER  FCA CANYON  C.  ,) 224 223  r i 92 0/14  92 0/15  92 0/11  92 0/10  -  51°46' N  BIG CREEK  220 2191 214  ■  2140%  V  nip II k^215 1  212 213 211  ..t..44.0  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet : 92 0/10,14,15  Comments :  Scale : I : 250,000  Fill. No.  251 52°00' N  208  RISKE CREEK  rive( •^  7.° ■ 206  207  173  FARWELL CANYON  cc)  ALKALI LAKE  O  92 0/16 92 0/9  0 0  0  0  PI 0  N  N  1^, , —^\ . <^ .  rn^  N  .0  O 1.  'DOG CREEK  CR.  GANG RANCH ak s  \  crc ^ 51° 30'  1  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet 92 0/9,16  Comments  Scale ; I : 250,000  Fig. No.^A-!8  ^ ^ ^  252 ^\  ^\  CK^1  6 ^.  '^I ,^ \  ÷  237 •  \ I^\  ■  •  \  ^236^23E^\  i  \ \^I  ,  .t. 4... --^... -^...,^.4, - - -^-,...88...., ., 1 ,  --  ....  e  I I 8  -\-- , 1  A  ,  SLACK \ DOME MTN.  \  ....  \  ..^  5'  ,  ,  -- ^  c-s \^-.), i \ i  ,. ^.....^--,,..  ir ,........... [233  \  I  r  ■  ^,  \  "I -5  )  \  \  -A r-€.1;"-  /  I'  \  \ i 1 --- ---i  GRINDER  I i  51°30' N  .  I ,'^l  A ,/ \  i  \_^,,...\_,.." ......,  —  -..c \  CI  'A la  7  CD  ct• la  '.4. 92 0/8  92 0/ 7  44.-  92 0/ 2  An 0  -,  92^0/ 1  di  0 ....>  ________/--------..___C.Ns  .3a_ <re.■ .73  ,  ...  .*-  .., / i  "P If a-  NINE  .w.  o  "• i  MIL E^RIDGE^0 <1.%  3 3 -0 to •  N N ...  -0 0 • N N  Tc. en A  51•00 N  + I  ROCK  SAMPLE / STATION LOCATION  NTS Map Sheet :^92 0/1, 7,8 Scale ' 1: 250,000  Comments: Fig. No.  MAP A-If  253  51° 45' N  8 N  13 • `  4  P -- DAVIDSON -  •RIDGE  e^I  I 0/12 112 0/5  PIS" LK.  39 • • 38  1  MOUNT TAT LOW  LOWER  \TASEKO  t 51.15 . N  i  -1 I LAKE  'I  ROCK SAMPLE / STATION LOCATION MAP NTS Map Sheet^92 0/ 5, 12 Scale 1: 250,000  Comments Fig. No.^A-20  254  52°00' P4  411111i  NIN 1411*  KLEE:A litik KLEENE98  19.9"1111  '  MINER ^ ,..„ LAKE  Thlw  .  TATLA LAKE  197  _246 • 247  BLUFF^  92 N /15  LAKE i^  92 P4/ 10  NWT  A  MOLINTA/N  ti 4.,  -0  0  O  N  N 51°30' N  ROCK SAMPLE / STATION LOCATION MAP NTS Mop Sheet : 92 N/ 10,15 Scale : I: 250,000  Comments: Fig. No.^A 21 -  255  ROCK SAMPLE / STATION LOCATION ^MAP NTS Map Sheet :^92 N / 8, 9,16 Scale :^I : 250,000  Comments = Fig. No.  A-22  256  APPENDIX B STRATIGRAPHIC SECTIONS FOR THE CHILCOTIN-NECHAKO REGION  257  SECTION 1 - REISETER CREEK 1  259  SECTION 2 - REISETER CREEK 2  260  SECTION 3 - REISETER CREEK 3  262  SECTION 4 - GRAMOPHONE CREEK  263  SECTION 5 - MEED CREEK AREA  264  SECTION 6 - NORTH OF MEED CREEK  266  SECTION 7 - CANYON CREEK 1  267  SECTION 8 - CANYON CREEK 2  268  SECTION 9 - CANYON CREEK 3  269  SECTION 10 - CANYON CREEK 4  271  SECTION 11 - BULKLEY RIVER IN SMITHERS  273  SECTION 12 - NEAR TELKWA COAL MINE 1  274  SECTION 13 - NEAR THE TELKWA COAL MINE 2  277  SECTION 14 - HOUSTON TOMMY CREEK 1  278  SECTION 15 - HOUSTON TOMMY CREEK 2  279  SECTION 16 - DENYS CREEK - COMPOSITE SECTION  281  SECTION 17 - MORICE RIVER/LAKE AREA  282  SECTION 18 - MORICE LAKE ROAD  283  SECTION 19 - SWING PEAK  284  SECTION 20 - GOSNELL CREEK  285  SECTION 21 - km 30 on the HONOLULU ROAD  286  SECTION 22 - HONOLULU ROAD  287  SECTION 23 - NAZKO FALLS ROAD  289  SECTION 24 - NAZKO D-96-E WELL  290  SECTION 25 - CHILCOTIN B-22-K WELL  294  SECTION 26 - POTATO RANGE  296  SECTION 27 - RIDGE WEST OF MOUNT TATLOW  301  258  SECTION 28 - VICK CREEK  309  SECTION 29 - TASEKO RIVER  312  SECTION 30 - CHILKO RIVER  314  SECTION 31 - CHURN CREEK 1  316  SECTION 32 - CHURN CREEK 2  317  SECTION 33 - CHURN CREEK 3  320  SECTION 34 - CHURN CREEK 4  322  SECTION 35 - CHURN CREEK 5  325  SECTION 36 - CHURN CREEK 6  328  SECTION 37 - ANAHIM FLATS  330  259  SECTION 1 - REISETER CREEK 1 (93L/14; UTME 615.760, UTMN 6086.310) Starting section at creek level, elevation 1460', bedding 100/58SW, through the south limb of an anticline. - 0 - 1.8 m (Base of section) Fine grained, medium grey siltstone with black speckles ( < lmm in diameter). Weathers rusty red, very soft, has a silky sheen, highly fissile. Sample J89005-01 - 1.8 - 2.3 m  Coarse grained sandstone, pale grey/brown, highly fractured. Occasional small clasts — 5mm in diameter, black with slickensides. Weathers rusty. Sample J89-005-02. - 2.3 - 2.8 m  Fine grained sandstone, medium to dark grey, weathers rusty, highly fissile, calcite on fractures. Samples J89-005-03 - 2.8 - 7.4 m  Coarse grained sandstone, weathers slightly rusty, lots of euhedral pyrite . Horizontally laminated Lams 3-5mm wide. Sample J89-005-04 - 7.4 - 12.4 m  Interbedded shale and sandstone. Sandstone layers vary from 3-11cm wide. Shale layers vary from 2-8cm wide. Shale is medium grey, weathers rusty red close to surface, very fissile. Sand is repeating coarsening upward layers each 15mm thick. Outcrop is highly fractured, calcite fills open spaces, weathers dark rust. Shale sample J89-005-05, sandstone sample J89-005-06. - 12.4 - 14.5 m  Greywacke, very friable, medium grey with black metallic looking "woody pieces" ( < lcm long). Weathers rusty in places, rest is pale grey. Cut by a white quartz vein (080/90) 20cm wide. Greywacke sample J89-005-07. - 14.5 - 20.5 m  Covered  - 20.5 - 26.5 m  Interbedded sandstone and shale. Bedding 120/30SW. Sandstone is coarse grained, siliceous, laminated on weathered surface, weathers brown/grey. Shale is very friable, sandy. Sandstone sample J89-005-09, shale sample J89-005-08. - 26.5 - 29.5 m  Sandy shale, fine grained, highly fissile, pale grey brown. Has small (max. 6mm diameter), soft, rounded, black blebs. Sample J89-005-10  260  SECTION 2 - REISETER CREEK 2 (93L/14; UTME 615.760 UTMN 6086.390) Starting section at elevation 1450', bedding 107/53NE, through the north limb of an anticline. - 0 - 9 m (Base of section) Interbedded shale and dirty, medium grained sandstone. Lots of biotite in the sand, Sample J89-006-01. Shale sample J89-006-02. Channel of coarse grained sandstone cuts the shale, sample J89-006-03. - 9 - 12 m  Covered, probably shale.  - 12 - 15.15m  Very coarse grained sandstone, forming a channel. Fines up from small pebbles (max. 5mm diam.) at the base. Minor cross-bedding. Sample J89-00604 - 15.15 - 19.5 m Covered, probably shale. - 19.5 - 21 m Sandstone, medium grained, micaceous. Sample J89-006-09 - 21 - 22.9 m  Covered, probably shale.  - 22.9 - 25.9 m Sandstone, fine grained, micaceous. Sample J89-006-10. - 25.9 - 27.4 m  Shale. Sample J89-006-11  - 27.4 - 29.5 m  Interbedded siltstone and sandstone. Sandstone layers 15 cm thick, fine grained, Sample J89-006-12. Siltstone layers 8 cm thick, thinly bedded (5mm wide), Sample J89-006-14. - 29.5 - 32.8 m - 32.8 - 37.3 m - 37.3 - 39.1 m - 39.1 - 40.6 m - 40.6 - 43.6 m  Sandstone, medium grained. Sample J89-006-13. Shale. Sample J89-006-15. Sandstone, medium grained. Shale. Base of beds show wavy ripple like marks. Sample J89-006-16.  Interbedded sandstone and fissile sandstone. Lenticular bedding. Ripple like marks on base of beds. Sandstone is micaceous and has dark grey nodules 3 cm in diameter that weather bright rusty orange.  261  - 43.6 - 48.4 m - 48.4 - 49.5 m  Covered. Sandstone, medium grained. Sample J89-006-17.  - 49.5 - 49.65 m Sandstone, coarse grained, black, micaceous, sulphurous. Sample J89006-18. - 49.65 - 49.8 m Siltstone, finely layered (5mm thick), micaceous. Sample J89-006-19. - 49.8 - 60.3 m - 60.3 - 61.8 m - 61.8 - 69.3 m - 69.3 - 72.3 m 22.  Sandstone, coarse grained. Weathers white/limey. Sample J89-006-20. Shale. Sample J89-006-21. Sandstone, coarse grained. Siltstone/shale. Rare pebbles 1cm long in siltstone. Sample J89-006-  262  SECTION 3 - REISETER CREEK 3 (93L/14; UTME 615.500 UTMN 6086.150) Section in Reiseter Creek under the bridge on the Telkwa High Road. This section should be higher than section 1 - assuming no faulting. - 40 m Interbedded siltstone and shale. Siltstone is silky grey with hard, dark grey pebbles 2 cm in diameter. Shale is dark grey with black specks. Siltstone beds are 2 m thick , shale beds 1 m thick. The whole outcrop is highly fractured with foliations parallel to bedding and spaced 5 mm apart with larger fractures at right angles. Siltstone and shale are cut by sandstone channels 2 m high by 4 m wide. Sandstone is medium grained, pale grey, hard, mainly quartz, fairly well sorted.  263  SECTION 4 - GRAMOPHONE CREEK (93L/14; UTME 613.750 UTMN 6094.250) Section in Gramophone Creek starting at elevation 2350'. -0-1m  Sandstone, medium grained, dark grey, well sorted, minor muscovite, composed mainly of chert and quartz. Flat lying. Sample J89-249-01. - 1 - 1.5 m  Interbedded Sandstone and siltstone. Siltstone, pale grey, has mud cracks and burrows along bedding plains. Sandstone, fine grained, pale grey, well sorted, hard. individual Sandstone beds are 5 cm thick, siltstone beds are 2- 10 cm thick. Siltstone Samples J89-249-02,03,06. - 1.5 - 4.5 m  Massive Sandstone in erosional contact with underlying interbedded unit. Base of Sandstone has angular, black or light grey, chert pebbles and minor white quartz pebbles 5mm in diameter (channel lag ?) Sample J89-249-04. Grades up from coarse grained to medium grained Sandstone, well sorted, composed mainly of chert and quartz. Sample J89-249-05. - 4.5 - 24.5 m  Interbedded shale and Sandstone. Shale, black, Very fine grained, splintery, micaceous. Sample J89-249-07,08. Sandstone, medium grained, dark grey, well sorted, has pebbles at base of bed but does not look like a channel. Shale beds 2 - 4 m thick, Sandstone beds 0.75 - 1.5m thick. Some shale beds grade up to Very fine grained, black Sandstone, Samples J89-249-09,10. See wood fragments in the Sandstone - none were seen in outcrop only in float within the creek, also boulders of conglomerate, Samples J89-249.  264  SECTION 5 - MEED CREEK AREA (93L/14; UTME 614.900 UTMN 6092.890) Section beside a logging road at elevation 2860'. - 3 m (base) Sandy shale, fine grained, black/brown. Sharp contact with overlying mudstone. Sample J89-050-02 Mudstone, black, organic matter rich. Sample J89-050-01. Grades up to overlying Mudstone and siltstone. Thinly laminated mudstone and siltstone. Sample J89-050-03. Sharp contact with overlying Sandstone. Sandstone, coarse grained, grey. Sample J89-050-04. (further up the same logging road, elevation 2980') - 2 m (elevation 2980') Sandstone, coarse grained, pink and grey, lots of organic matter branches etc. Well sorted Sandstone, sub-angular grains. Flat lying. Sample J89-05101. - 1 m (elevation 3080') Sandstone, coarse grained, pink. Underlain by mudstone rich in organic matter, silty laminations and rip up clasts. - ? (elevation 3100') Poorly exposed conglomerate, pink, coarse grained Sandstone matrix surrounding clasts up to 8cm long, larger clasts are more rounded than smaller clasts. - 10m (elevation 3060') Sandstone, coarse grained, brown (white grains in a brown background), grades to slightly finer Sandstone northwards. Well sorted, subangular to subrounded. Organic matter rich layers/laminations. Sample J89-054-01. - 5m (elevation 3020') Conglomerate, clast supported, matrix is pink, coarse grained sand. Rounded clasts, up to 10cm long. Clasts are aligned parallel to bedding. Clasts are composed mainly of volcanics, siltstone and mudstone, little chert. Organic matter in blebs. Sample J89-055-01. - Elevation 3340' Sandstone, coarse grained, pink - same. - Elevation 3500' Interbedded Sandstone and conglomerate. Conglomerate beds 2m thick, Sandstone beds lm thick. Sandstone grades from very coarse grained to pebbly, brown, well sorted, has organic matter. Sandstone grades into heterolithic, clast supported conglomerate, grey brown, sub-rounded clasts in a very coarse  265  grained sand matrix with pebbles. Conglomerate is poorly sorted, max clast size is 15 cm long, large clasts are well rounded, see some organic matter in blebs and rare lams within the conglomerate. Clast composition 20% laminated siltstone and mudstone, 25% volcanic, 5% augite porphyry, 50% fine grained sediments. Samples J89-057-01,02. - Elevation 3260' Sandstone, coarse grained, pink - same.  266  SECTION 6 - NORTH OF MEED CREEK (93L/14; UTME 612.540 UTMN 6094.460) Section along a logging road just north of Meed Creek, starting at elevation 2300', bedding 105/45N) -0- 18 m  Interbedded conglomerate and sandstone. Heterolithic clast supported conglomerate, Fairly well sorted, brown, coarse grained sand matrix. Clasts are chert, volcanic and fine grained sediments. Sample J89-059-01. - 18 - 28.5 m  Siltstone, dark grey. Sample J89-060-01.  - 28.5 - 31.5 m  Sandstone, coarse grained, brown grey, well sorted, sub-angular. Sample J89-060-02. - 31.5 - 52.5 m - 52.5 - 55.5 m - 55.5 - 61.5 m  Siltstone - same. Dyke, fine grained, pale grey. Sample J89-060-03. Siltstone - same.  267  SECTION 7 - CANYON CREEK 1 (93L/14; UTME 624.100 UTMN 6072.800) Section in Canyon Creek starting below the bridge on Telkwa High Road at elevation 1850'. Bedding 150/24NE. - 0 - 6 m (Top of section) Interbedded shale and sandy siltstone. Shale beds are 5-13 cm thick, siltstone beds are 8 cm thick. Shale is micaceous. Sample J89-014-01. - 6 - 9.3 m  Sandstone, fine grained, green/grey, micaceous. Sandstone coarsens down section and contains rounded, black clasts (Shale ?). Sample J89-014-02. - 9.3 - 12.3 m J89-014-05.  Shale, black, micaceous, has symmetrical ripples (marine ?). Sample  268  SECTION 8 - CANYON CREEK 2 (93L/14; UTME 626.140 UTMN 6072.740) Section in Canyon Creek, starting at 2100', bedding 175/65NE. - 0 - 21m  Sandstone, fine grained to medium grained, green, micaceous. Sample J89-016-01. - 21 - 30 m - 30 - 57 m - 57 - 79.5 m  Covered. Sandstone, fine grained, green, micaceous. Covered.  - 79.5 - 105 m  Sandstone, fine grained, green, micaceous. Sample J89-015-01. Alternating layers of hard Sandstone and fissile Sandstone. Hard Sandstone beds are 10-20 cm thick, fissile Sandstone beds are 6-20 cm thick. Hard Sandstone beds show faint ripple marks on weathered surface. -105 - 108 m  Interbedded shale and siltstone. Siltstone beds are 6 cm thick, shale beds are 10 cm thick. - 108 - 120 m  Sandstone, fine grained, brown green.  269  SECTION 9 - CANYON CREEK 3 (93L/14; UTME 626.670 UTMN 6072.600) Continuing the section in Canyon Creek, starting at elevation 2170' where section 2 ended. - 0 - 42 m  Covered.  - 42 - 45 m  Sandstone, fine grained, green, micaceous Thin (1mm) organic matter rich layers and thin (2mm) limonitic bands and blebs (4mm diameter). Sample J89-017-01. - 45 - 51 m  Interbedded shale and siltstone. Shale beds 6-25 cm thick, siltstone beds 8-15 cm thick. Siltstone is black, siliceous with lots of calcite veinlets. Shale Sample J89-017-02, siltstone Sample J89-017-03. - 51 - 72 m - 72 - 75 m rich. - 75 - 84 m - 84 - 85.5 m (2.5cm). - 85.5 - 87 m - 87 - 90 m - 90 - 93 m - 93 - 94.5 m - 94.5 - 96 m  Covered. Sandstone, dark grey/green, fine grained, micaceous, organic matter Covered. Sandstone, fine grained, dark green/black, micaceous, thinly bedded Covered. Sandstone, fine grained, dark green/black, micaceous, thinly bedded. Covered. Sandstone, fine grained, dark green/black, micaceous, thinly bedded. Covered.  - 96 - 103.5 m  Sandstone, medium grained, green, micaceous, organic matter plus rounded fragments of mudstone. Sample J89-017-04. - 103.5 - 108 m Covered.  270  - 108 - 112.5 m Sandstone, medium grained, green, micaceous. - 112.5 - 114 m Sandstone, fine grained, darker green.  271  SECTION 10 - CANYON CREEK 4 (93L/14; UTME 627.100 UTMN 6072.750) Section in Canyon Creek, starts where section 3 ended. -0-3m  Covered.  - 3 - 19.5 m  Sandstone, fine grained, dark to medium green, micaceous, organic matter disseminated and concentrated in blebs. Organic rich layers 1mm thick, limonitic bands cross-cut organic rich bands. Sample J89-018-01. - 19.5 - 24 m - 24 - 25.5 m - 25.5 - 27 m  Covered. Sandstone - same. Covered.  - 27 - 34.5 m  Sandstone, fine grained, grey/brown, less micaceous, disseminated organic matter. - 34.5 - 54 m  Covered.  - 54 - 87 m  Sandstone, fine grained, green, micaceous, disseminated organic matter. Very finely laminated <1mm. - 87 - 174 m  Covered.  - 174 - 193.5 m Sandstone, fine grained, green, micaceous, disseminated and blebs of organic matter. Sample J89-018-02. - 193.5 - 238.5 m Covered. - 238.5 - 244.5 m Sandstone, fine grained, green, micaceous. - 244.5 - 280.5 m Covered. - 280.5 - 297 m Sandstone, very fine grained, green, micaceous, organic matter as angular pieces 5mm x 15mm. Coarsens slightly upsection. Sample J89-018-03. - 297 - 324 m  272  Covered. - 324 - 328.5 m Sandstone, medium grained, green, very micaceous, organic matter rich layers. - 328.5 - 352.5 m Covered. - 352.5 - 354 m Sandstone, medium grained - same. - 354 - 520 m  Covered.  (ending section at elevation 2300')  273  SECTION 11 - BULKLEY RIVER IN SMITHERS (93L/14; UTME 620.200 UTMN 6068.650) Section on the west side of the Bulkley River in Smithers behind the sawmill. - 0 - 0.5 m  Coal, highly fractured, light and plasticy, black, has carbonized wood fragments. Sample J89-279-01. - 0.5 - 2 m  Siltstone, dark grey, micaceous, finely laminated with black carbonaceous lams lmm wide, 2mm apart, has many carbonized wood fragments (2mm x 2mm). Well lithified. Sample J89-279-03 - 2 - 2.5 m  Felsic volcanic ? (or a sill), fine grained, pale brown, massive, well sorted, well lithified. Sample J89-279-2. - 2.5 - 6.5 m  Interbedded Sandstone and silty Sandstone. Sandstone, medium grained, green, micaceous, well sorted, well lithified, carbonized wood. Sample J89279-04. Silty Sandstone, fine grained, grey green, micaceous, finely laminated with lams < 1mm thick and 1mm apart, friable, has carbonized wood fragments. Sample J89-279-05. Sandstone beds are 10 cm thick, silty Sandstone beds are 30 cm thick.  274  SECTION 12 - NEAR TELKWA COAL MINE 1 (93L/11; UTME 620.650 UTMN 6053.750) Section through a roadcut above the Telkwa Mine, elevation 2280', bedding 010/003NW. - 0 - 1.5 m (Base of section) Covered - 1.5 - 1.84 m  Sandstone, fine grained, has wood and concretions. Sample J89-007-  01. - 1.84 - 2.07 m - 2.07 - 2.25 m - 2.25 - 2.4 m - 2.4 - 2.6 m - 2.6 - 2.95 m  Mudstone, fine grained. Sample J89-007-02. Sandstone, fine to medium grained. Sample J89-007-03 Mudstone, fine grained. Sample J89-007-04. Sandstone fine to medium grained. Shale. Sample J89-007-05.  - 2.95 - 3.2 m  Sandstone, fine to medium grained. Concretions with coaly centres, Sample J89-007-07. - 3.2 - 3.45 m - 3.45 - 3.55 m - 3.55 - 3.73 m - 3.73 - 3.93 m - 3.93 - 4.41 m - 4.41 - 4.71 m - 4.71 - 5.34 m - 5.34 - 5.54 m  Mudstone, Sample J89-007-06. Sandstone, fine to medium grained. Mudstone, Sample J89-007-08. Sandstone. Mudstone. Sample J89-007-09. Sandstone. Mudstone. Sample J89-007-10.  275  Sandstone. - 5.54 - 5.97 m - 5.97 - 6.22 m  Mudstone, fine grained, dark blue grey. Sample J89-007-11. Sandstone.  - 6.22 - 6.93 m  Mudstone, fine grained, harder than earlier samples of Mudstone. Sample J89-007-12.  - 6.93 - 7.03 m - 7.03 - 7.79 m - 7.79 - 7.99 m - 7.99 - 9 m - 9 - 9.2 m - 9.2 - 10.72 m  Sandstone. Mudstone. Same as 7-12. Sample J89-007-13. Sandstone. Mudstone, same as 7-12. Sample J89-007-14. Sandstone. Mudstone. Sample J89-007-15.  - 10.72 - 10.82 m Sandstone, very fine grained. Sample J89-007-16. - 10.82 - 11.48 m Mudstone, micaceous. Sample J89-007-17. - 11.48 - 11.56 m Sandstone, fine grained, micaceous. - 11.56 - 11.83 m Mudstone, same as 7-17. Sample J89-007-18. - 11.83 - 11.91 m Sandstone, fine grained, micaceous, lots of organic matter. Sample J89-007-19. - 11.91 - 12.88 m Mudstone, micaceous. Sample J89-007-20. - 12.88 - 12.98 m Sandstone, fine grained. Sample J89-007-21. - 12.98 - 13.67 m  276  J89-007-22.  Mudstone, striped dark grey, pale grey, brown repetitively. Sample  - 13.67 - 13.77 m Sandstone. - 13.77 - 14.18 m Mudstone, finely striped with alternating bands of brown (2mm) and pale grey (6mm), micaceous. Sample J89-007-23. - 14.18 - 14.26 m Sandstone, fine grained, micaceous, faint lams lcm apart. - 14.26 - 14.74 m Mudstone, micaceous, finely laminated ( < lmm). Sample J89-007-24. - 14.74 - 14.79 m Sandstone. - 14.79 - 15.07 m Mudstone, striped dark grey, medium grey, brown, light grey. Stripes 3mm thick, micaceous. Sample J89-007-25. - 15.07 - 15.27 m Sandstone, fine grained, finely laminated organic rich and non-organic rich layers < 1mm thick, micaceous. Sample J89-007-26. - 15.27 - 15.55 m Mudstone, striped pale grey (2mm) and brown (4mm), micaceous. Sample J89-007-27. - 15.55 - 15.65 m Sandstone, fine grained, micaceous, same as 7-19. Sample J89-007-28. Alternating mudstone and sandstone sequence continues for another 3 m. Above this is 1.5 m of burnt red soil with rare chunks of coal.  277  SECTION 13 - NEAR THE TELKWA COAL MINE 2 (93L/11; UTME 621.140, UTMN 6053.450) Section through a roadcut near the Telkwa Coal Mine, starting elevation 2300', bedding 160/14NE. This section lies above the other section close to Telkwa Coal Mine. - 0 - 2.03 m  Covered.  - 2.03 - 2.39 m - 2.39 - 2.44 m - 2.44 - 2.69 m - 2.69 - 2.79 m  Mudstone, thinly laminated ( < 1mm), micaceous. Sample J89-008-01. Sandstone, fine grained. Sample J89-008-02. Mudstone, micaceous. Sample J89-008-03. Sandstone, fine grained, same as 8-2.  - 2.79 - 3.68 m  Mudstone, micaceous. Sample J89-008-04.  - 3.68 - 3.76 m  Sandstone, fine grained, medium grey with thin (1-2mm) grey bands. Sample J89-008-05. - 3.76 - 4.19 m - 4.19 - 4.27 m -4.27-4.91 m  Mudstone, micaceous. Sample J89-008-06. Sandstone, fine grained, same as 8-2. Mudstone, micaceous, same as 8-6. Sample J89-008-07.  - 4.91 - 7.33 m  Interbedded Sandstone and Mudstone. Sandstone layers vary from 2.5cm-28cm wide, Mudstone layers vary from 10-36cm wide. Sandstone, fine grained, thinly laminated (1mm). Mudstone, striped bands of dark grey and dark brown (5mm thick) and occasional bands of pale grey 2mm thick, micaceous. Sandstone Sample J89-008-08, Mudstone Sample J89-008-09. Covered.  278  SECTION 14 - HOUSTON TOMMY CREEK 1 (93L/7; UTME 636.850 UTMN 6013.200) Section in Houston Tommy Creek, close to Morice River, starting elevation 2100' in the Creek. -0- 12 m 261-01.  Sandstone, medium grained, green, siliceous, massive. Sample J89-  - 12 - 48 m  Sandstone, medium grained, pale grey, thinly bedded (0.5-1 cm thick). Sandstone is mainly quartz with pyrite and black specks. Sample J89-261-02. - 48 - 66 m  Interbedded siltstone and Sandstone. Siltstone beds 2 - 4 m thick, Sandstone beds from 0.75 - 3 m thick. Siltstone, dark grey, very micaceous, finely laminated parallel to bedding, lams 2mm thick interbedded with fine grained Sandstone lams. Sandstone, medium grained, white, well sorted, has small (10mm x 5mm) pale grey mud clasts and thin lams of mudstone and discontinuous lenses. Burrows on bedding plane. Sample J89-261-04. - 66 - 90 m  Interbedded shale and Sandstone. Shale beds 2 - 4 m thick, Sandstone beds lm thick. Shale, dark grey, micaceous. Sample J89-261-05. Sandstone, coarse grained, brown, feldspathic, has pale grey, angular mud clasts (3mm x 6mm), also mud lams and lenses. Sample J89-261-7.  279  SECTION 15 - HOUSTON TOMMY CREEK 2 (93L/6; UTME 627.500 UTMN 6018.750) Section in Houston Tommy Creek, starting at elevation 2950'. -0-1m  Sandstone, fine grained, grey, well sorted, siliceous, has carbonized wood fragments. Weathers spheroidally. Sample J89-282-02. - 1 - 1.15 m  Sandstone, pebbly, pale grey, poorly sorted, weathers white, pebbles are angular, chert, pale pink or maroon feldspathic volcanics up to 3 cm in diameter, pebbles weather rusty. Sandstone has carbonized wood fragments. Sample J89-28203,05. - 1.15 - 1.55 m  Shale, dark grey to black, has carbonized wood fragments, weathers medium grey. Sample J89-282-01,06. - 1.55 - 2.55 m  Sandstone, fine grained, grey, siliceous, well sorted, has plant fossils, highly fractured, weathers, very pale grey. Sample J89-282-04. The above beds repeat a number of times to give a section 20m thick. This 20m section is overlain by the following: - 20 - 30 m - 30 - 34 m - 34 - 35 m  Pebbly Sandstone grading up to massive Sandstone. Sandstone, bedded. Shale.  - 35 - 35.5 m  Coal, banded, alternating dull and bright bands (15% bright, 85% dull), bright bands 1cm thick, dull bands 1.5 - 3 cm thick. Sample J89-282-07 - 35.5 - 36.25 m Coaly shale. - 36.25 - 37.75 m Sandstone, dirty, mud laminations. Sample J89-282-09. - 37.75 - 38.75 m Siltstone, thin bedded (1cm). Sample J89-282-10. - 38.75 - 46.75 m Interbedded Sandstone and Siltstone. - Covered for several hundred metres. - 30m  280  Interbedded shale and Sandstone. Shale beds 3m thick, Sandstone beds 0.30 m thick. Shale, dark grey brown, weathers dark grey, pale grey or rust. Highly fractured. Sample J89-283-01, J89-284-01. Sandstone, occurs mainly as layers of concretions up to 40cm in diameter.  281  SECTION 16 - DENYS CREEK - COMPOSITE SECTION (93L/6; UTME 611.300 UTMN 6029.150) Section in the Denys Creek area, starting at elevation 3880'. - 0 - 5 m (base of section) Sandstone, medium grained, pale grey green, well sorted, micaceous, thinly bedded (0.5 - 2 cm thick), planar laminated, has carbonized wood and plant fragments, discontinuous siltstone lenses. Sample J89-262-1. -5-8m  Siltstone, dark grey, micaceous, has carbonaceous material, minor fine grained, green, micaceous Sandstone beds 10 cm thick. Sample J89-263-01. - 8 - 8.5 m 264-01.  Coal, brittle, highly fractured, has tiny folds, very light. Sample J89-  - 8.5 - 16.5 m  Interbedded Sandstone and siltstone. Siltstone, dark grey, micaceous, thinly bedded with beds 2cm thick. Sandstone same as earlier. -7  Covered. - 50m  Interbedded Sandstone and siltstone (60% Sandstone, 40% siltstone). Sandstone, fine grained, brown grey, well sorted, micaceous. Siltstone, dark grey, micaceous. Sandstone beds 2 - 4 cm thick, siltstone beds 2 cm thick. Sample J89-2661. Towards top of unit see coaly float but no outcrop of coal.  282  SECTION 17 - MORICE RIVER/LAKE AREA (93L/3; UTME 640.550 UTMN 6018.500) Section beside road, opposite Morice River at Km 19. - 0 - 10 m  Mudstone, black, pyritic partings 2mm wide between mudstone layers 5mm wide. Sample J89-030-01. - 10 - 25 m  Shale coarsens up to interbedded shale and siltstone to fine grained Sandstone. Interbedded shale and siltstone has lots of organic matter, Sample J89030-03. Sandstone , fine grained, micaceous, Sample J89-030-02.  283  SECTION 18 - MORICE LAKE ROAD (93L/3 UTME 621.750 UTMN 6001.325) Section above km 48 on the Morice Lake road. - 0 - 20 m (Top of section) Sandstone, fine grained, greenish brown, planar laminated beds, lams 2mm to 1cm apart (only seen on weathered surface). Very little mica, some rip up clasts and minor organic matter, well sorted. Sample J89-064-01. - 20 - 22 m  Sandstone, fine grained, bright green, well sorted, minor organic matter concentrated in thin lams Sample J89-064-02. Also at this location is a boulder of black, fine grained Sandstone, looks like oil sand Sample J89-064-03. - 22 - 92 m  Sandstone, fine grained, well sorted, minor organic matter and rip up clasts, slightly more mica than 64-1. Planar laminated parallel to bedding. Sample J89-064-04.  284  SECTION 19 - SWING PEAK (93E/11; UTME615.700 UTMN 5945.250) Section up Swing Peak, above an old camp. Starting at elevation 4050'. - At least 30m (Top of section - contact with overlying Kasalka Group) Breccia/Conglomerate, clast supported, fine grained, green, sandy matrix. Clasts are mainly angular and composed of chert, vesicular volcanics, fine grained pink or purple rock, max 15 cm long, poorly sorted. Sample J89-083-01. - 30 - 42 m  Sandstone, grades up into overlying conglomerate. Sandstone, medium grained, black, some biotite. Conglomerate starts with small pebbles and grades sharply up to large rounded clasts max. 15cm diameter, of siltstone, chert and volcanics. Sample J89-084-01. - 42 - 54 m  Sandstone, fine grained, green, micaceous, well sorted, blebs of organic matter. Base of beds have trace fossils - trails lcm wide going in all directions. Sample J89-085-01. - 54 - 81 m  Bedded Sandstone, fine grained, brown. Individual beds are 10-40 cm thick. Occasional shaley beds 5cm thick occur within the Sandstone. Some patches of Sandstone are more resistant and weather rustier - may be concretions. Base of Sandstone beds are bumpy with silts in the depressions. The Sandstone has rip up clasts and blebs of mudstone. Sandstone Sample J89-086-01, shale Sample J89-08602. - 81 - 123 m Massive Sandstone grades up into overlying bedded Sandstone. Sandstone, fine grained, brownish green, micaceous, planar black laminations, rip up clasts of mudstone Laminations are 2mm to 2cm thick and spaced 10 - 50 cm apart. Sample J89-087-01. - 123 - 132 m  Finely laminated Sandstone. Sandstone, fine grained, dark grey green, well sorted, micaceous. Sandstone has siltstone lams lmm thick, 2mm apart, most are planar some are convolute. Siltstone is black, and very micaceous. Sample J89088-01. - At least 5m  Thinly bedded Sandstone in fairly sharp contact with overlying laminated Sandstone. Sandstone, medium grained, orange/grey/white, micaceous, well sorted, planar bedded, individual beds are 2-5 cm thick. Has mudstone rip up clasts. Sample J89-089-01. (rest of section was inaccessible).  285  SECTION 20 - GOSNELL CREEK (93L/3; UTME 605.000 UTMN 6008.300) Section measured in Gosnell Creek 100m west of a bridge crossing the creek. Eocene sediments, also seen in Thautil River. - 0 - 1.5 m  Laminated siltstone, weathers dark grey, fresh is dark grey, lams are 2mm apart, cleaves along bedding planes lcm apart. Some beds are limey with recessive lams - sparry calcite lams 1 to 4mm apart, calcite is brownish red. - 1.5 - 2.3 m  Finely laminated siltstone with limey mud beds. Siltstone weathers black to dark brown, fresh is medium grey with a dark weathering rind 3mm thick. Lams are 2 to 4 mm apart. Towards the top of the bed are limey mud layers 20 and then 2 cm apart Limey beds weather muddy brown, fresh is dark grey, thinly layered with layers 1 to 2 m apart, some layers look like compressed shell fragments replaced by calcite, limey beds are wavy with spots and wiggles on the surface. - 2.3 - 2.57 m  Siltstone, weathers black with manganese staining, fresh is dark blue green (glauconite?) with black calcareous blebs, tiny acicular black slivers and pyrite, also calcite concretions. Siltstone is thinly laminated with lams 1mm apart. - 2.57 - 7.87 m  Shale, weathers dark brown grey, fresh is dark grey, slightly gritty, highly fractured, some calcite concretions elongate parallel to bedding maximum 15 x 40 cm. Towards the top of this unit the shale weathers pale muddy brown, fresh is dark brown/grey. - 7.87 - 8.62 m  Fine grained sandstone, weathers pale brown, fresh is pale green, pale pink or white with rusty blebs (pyrite?) 1mm in diameter and bright green or pink fragments < 1 to 1mm in diameter. Fairly hard. - 8.62 - 13.12 m Mudstone, weathers dark to medium brown, fresh is medium brown, very flaggy - layers < 1 to 4mm thick, plant fragments are visible on some layers. - 13.12 - 20.62 m Conglomerate, heterolithic, clast supported, fairly poorly sorted. Matrix is medium to coarse grained pale green to muddy sandstone. Clasts are subangular to rounded and vary from 5 to 20 cm in diameter. Clast composition: 60% fine grained basalt and amygdaloidal basalt; 20% maroon volcanics, 10% augite porphyry and 10% chert and sandstone.  286  SECTION 21 - km 30 on the HONOLULU ROAD (93B/11,UTME 470.400 UTMN 5840.200) This section is 229 m thick in total but is not continuous, there are many covered intervals ( may be covering more recessive units ). Bedding varies from 000/24W to 000/60W and back to 000/24W. Conglomerate interbedded with sandstone. - 0 - 39.26 m  Conglomerate, clasts supported with clasts parallel to bedding. Weathers rusty or red, friable. Overall, beds crudely grade up from large pebbles ( max. 10 cm in diameter, average 5 cm ) to tiny pebbles less than 1 cm in diameter. Ninety percent of the pebbles are composed of black, white, milky, grey and red chert; the remaining ten percent are composed of soft clayey, white or pale brown fragments or grey green, medium hard pebbles (volcanic ?). Chert pebbles are subrounded, others are rounded. Some chert pebbles are veined. - 39.26 - 127.59 m Interbedded conglomerate (66%) and sandstone (34%). Sandstone is coarse grained and composed primarily of black and white chert. The weathered surface of the sandstone has large, recessive holes, up to 50 cm in diameter (as though it once contained large concretions ?) and is rusty or red in colour. Coarse grained sandstone beds are lm thick with clasts at the base aligned parallel to bedding, within the sandstone are occasional fining upward sequences 5cm wide grading from small ( < lcm diameter) pebbles up to coarse grained sandstone. Medium grained sandstone is rarely seen, it is micaceous and occurs in thin (10 cm wide), laminated (1-2 cm wide) beds within the coarse grained sandstone. Sandstone beds are poorly consolidated and crumble easily. Conglomerate is as described above. - 127.59 - 229 m Conglomerate, same as described above.  287  SECTION 22 - HONOLULU ROAD beside the bridge over the Nazko River (93B/11; UTME 471.500 UTMN 5837.700) Section is continuous and approximately 12 m thick. Bedding below a possible fault is 036/17E, below the fault bedding measures 350/13E. Some slickensides were seen on this outcrop. Interbedded sandstone, conglomerate and shale. Overall the sandstone and conglomerate weather rusty, the shale is highly friable and breaks into small squares. Fine grained beds are very hematitic. Whole outcrop is sheared up, strongly jointed and crumbly. - 0 - 0.80 m - 0.8 - 3.6 m  Chert pebble conglomerate. Covered, possibly volcanic.  - 3.6 - 3.8 m  Dark grey siltstone, very fine grained. Weathers rusty. Highly friable. No visible organic matter. Sample J90-003-09. - 3.8 - 4.3 m  Sandstone, coarse grained, cherty. Weathers rusty/greenish. Moderately well sorted, contains slightly larger maroon and black fragments. Sample J90-003-07. - 4.3 - 5.1 m  Fine grained sandstone or volcanic ? Weathers hematitic maroon. Fresh surface is grey. Extremely friable. Sample J90-003-06. - 5.1 - 6.35 m  Sandstone, fine grained, weathers rusty or grey, matrix weathers rusty. Very muddy, highly friable, contains minor fine organic material. Sample J90-00305. - 6.35 - 7.35 m  Chert pebble conglomerate, clast supported, weathers rusty. Sheared and faulted. Shows no obvious trend or grading and in general appears massive. Clasts are composed of 95% black, white and grey chert, the remaining 5% are softer dark grey material. Clasts vary in size from 1 to 8 cm in diameter, averaging 23 cm. Sample J90-003-04. - 7.35 - 8.35 m  Fine grained, grey, dirty sandstone, weathers rusty. Sandstone is very muddy with minor organic matter, see thin wisps of mud. Highly friable, slickensides on surfaces. Sample J90-003-03. - 8.35 - 9.85 m  Chert Pebble conglomerate, same as above.  - 9.85 - 10.65 m  288  Sandstone, dark grey, medium grained, weathers rusty, matrix is rusty. Moderately well sorted, has some slightly larger black fragments about 3mm across. Highly friable. Sample J90-003-02. - 10.65 - 11.65 m Sandy shale, dark grey , weathers rusty. Contains organic matter, highly friable. Sample J90-003-01. - 11.65 - 12.65 m Sandstone, medium grained composed primarily of black and white chert, matrix is rusty. Contains muddy lenses with some organic matter. Highly fractured, weathers pinkish. Sample J90-003-08.  289  SECTION 23 - NAZKO FALLS ROAD at km 8004 (93B/11, UTME 468.000 UTMN 5835.500) Whole outcrop weathers a very rusty orange or dark brown. Bedding 114/14SW. Could be a conglomerate channel cutting through finer facies. Interbedded conglomerate, sandstone and siltstone. - 0 - 0.5 m  Sandstone, medium grained. Weathers grey. Rich in organic matter. Soft, highly fractured. Sample J90-005-03. - 0.5 - 0.8 m  Siltstone. Weathers medium grey. Very friable and soft, breaks into small squares. Sample J90-005-02. - 0.8 - 2.8 m  Sandstone, medium grained, varies in thickness from 0.5 to 2 m. Weathers rusty or pale greenish brown. Composed mainly of chert. Shows some evidence of planar beds about 1.5 cm apart, the base of each bed is marked by small chert clasts 2 mm in diameter. Strongly jointed perpendicular to bedding. Sample J90-005-01. - 2.8 - 8.8 m  Chert pebble conglomerate, grades up from coarse to fine, at the base clasts average 3 cm in diameter, at the top the average is 1 cm. Conglomerate is very friable and highly fractured, clasts come out easily. Clasts are mainly chert or quartz with minor very soft, clayey white clasts or maroon clasts.  290  SECTION 24 - NAZKO D-96-E WELL Subsurface stratigraphic section derived from well log data and analysis of cuttings. Descriptions start at the top of the well. 0 to 30 m depth: Felsic volcanics. Beige-white with black specks, vuggy. 30 to 150 m  Interbedded conglomerate and sandstone with minor siltstone.  Conglomerate has sub-rounded, pebble to granule sized chert clasts,  predominantly buff to light grey, black, dark grey or green. Poorly consolidated, iron stained. Matrix is light grey, fine to coarse grained sand that is poorly sorted, has poor to fair consolidatation, sub-rounded to sub-angular grains, fair to trace porosity, kaolinite and silica cement, some iron staining and trace pyrite. Sandstone is very fine to medium grained, medium grey, poorly sorted, has fair to poor porosity, has some floating chert pebbles and granules, some iron staining, Kaolinite and silica cement, sub-angular to sub-rounded grains, fair consolidation, is sometimes silty and grades to conglomerate. Silstone is light grey, siliceous, arenenaceous, argillaceous or micaceous in part and often grades to very fine gra ined sandstone. Shale is light to medium grey, sub fissile, has trace carbonaceous material, is silty in part or slightly micaceous, often grades to siltstone. 150 to 400 m  Interbedded sandstone and shale with minor siltstone and conglomerate. Sandstone very fine to medium grained, light to medium grey, green, medium grey green or rarely white, poor to fair sorting, fair to well consolidated, sub angular to sub-rounded grains, silt and kaolinite cement sometimes calcite, no to trace porosity, silty in part grading to siltstone, very minor pyrite, argillaceous or carbonaceous in part, trace mica, some iron staining. Shale is dark grey-black to medium to dark grey, green, red brown to dark brown, has some hematite staining, rare carbonaceous material, fissile to platy, very fine grained sandstone and silty in parts, slightly micaceous, occasional iron concretions. Siltstone medium grey brown to green grey or dark grey, slightly micaceous, very argillaceous in part grading to fine grained sandstone, rarely calcic, occasionally arenaceous grading to very fine grained sandstone. Conglomerate White to light grey, pebble and granule sized clasts in a medium to coarse grained sandstone matrix, sub-angular clasts, poorly sorted, poor to fair consolidation, no porosity, calcic to kaolinitic cement. -  -  -  400 to 550 m  Interbedded shale and conglomerate with lesser sandstone and siltstone. Shale brown grey-dark grey, red brown, green, dark grey black, fissile, carbonaceous in part, sandy and silty in part grading to sandstone and siltstone, no porosity, micaceous in part. Conglomerate chert pebbles and granules as above, light brown, light grey, black, medium grey and light green chert, trace porosity, in a medium grey, coarse to fine rained sandstone matrix with fair to poor sorting, good consolidation, silt, kaohnite and calcite cement. Siltstone light to medium grey, argillaceous, slightly calcic, arenaceous grading to sandstone, micaceous in part. -  -  -  -  550 to 590 m  291  Shale with minor sandstone. Shale - medium grey, light green, red brown, some hematite staining, sub fissile, in part silty and sandy. Sandstone light to medium grey, very fine grained, fair sorting, sub-angular to sub-rounded grains, micaceous, argillaceous grading to shale, calcic and kaolinitic cement, no porosity. -  590 to 640 m  Sandstone with very minor shale. Sandstone light grey green to light grey, fine to medium grained, sub-angular to sub-rounded, poor to moderate sorting, silica cement and quartz overgrowths, argillaceous in part, carbonaceous lams, cherty in part, kaolimte and some silty cement, trace gluconite. Shale light to dark grey, blocky, slightly calcic in part, sandy in part, trace limestone, chert and pyrite. -  -  640 to 950 m  Shale with minor sandstone and siltstone. Shale medium grey to brown grey, grey green, medium to dark grey to black, red, purple, brown to rust, blocky, micaceous, carbonaceous, grades to siltstone in part, platey in part, iron stained, rare pyrite. Sandstone grey, brown, green, very fine grained to medium grained, sub-angular to sub-rounded to rounded, poor to moderate sorting, cherty, micaceous or carbonaceous in part, silica and calcite cement, rare siderite cement, argillaceous and silty. Siltstone grey to brown, blocky, micaceous, carbonaceous lams, grades to very fine grained sandstone. -  -  -  950 to 1293 m  Sandstone with minor shale and conglomerate. Sandstone grey to green or white, fine to medium grained, angular to sub-angular to sub-rounded, silica cement and some calcite, quartz overgrowths, slightly silty, micaceous in part, trace porosity, occasional chert clasts, trace carbonaceous material, pyrite and glauconite, shale stringers, argillaceous, rare patchy lighy oil stain. Shale grey to brown or red, platey to blocky, silty and micaceous in part, trace carbonaceous material. Conglomerate pebbles and granules of varicoloured chert, mainly grey and black. -  -  -  1293 to 1430 m Interbedded shale, conglomerate and sandstone. Shale green grey, red brown, black and purple, platey to sub blocky, micaceous, silty in part grading to siltstone, slightly calcic in part, carbonaceous in part. Sandstone green, white or grey, very fine to medium grained, poorly sorted, predominantly chert, grades to conglomerate, calcite and kaolinite cement, no porosity, sub-angular, slightly silty, some mica. Conglomerate pebbles and granules of grey and black chert. Rare white to buff dolomite and siliceous ooze. -  -  -  1430 to 1710 m Shale with minor sandstone, conglomerate and siltstone. Shale grey, green grey, black, brown and red, blocky to platey to sub fissile, micaceous in part, some floating rounded chert sand grains, in part silty grading to siltstone, slightly carbonaceous (carbonaceous and bituminous from 1550 to 1600 m). Sandstone grey, green grey, and white, very fine to medium grained, rarely coarse grained, poor to fair sorting, calcite, kaolinite and silica cement, no to poor porosity, angular to sub-angular to sub-rounded, micaceous, quartzose in part, rare fining upward sequences, rare dead oil stain at 1625 m. Conglomerate quartz and chert pebbles and granules, no porosity. Siltstone dark grey, silicic, grading to very fine grained -  -  -  sandstone.  292  1710 to 2250 m Interbedded conglomerate, shale and sandstone. Conglomerate pebbles and granules of white and grey chert,lesser black and rare red and orange, also some volcanic clasts, poorly sorted, coarse grained sandstone matrix of chert and quartz, or white fine to medium grained sandstone with a siliceous cement and minor dolomite. Shale red, green, black, grey, silty in part, blocky, rare carbonaceous material and floating quartz grains, waxy below 2150 m. Sandstone grey, white, green, very fine to fine grained, rare medium grained or coarse grained grading to conglomerate, sub-angular to sub rounded, poor to fair sorting, no porosity, silica cement, silica and dolomite cement below 1930 m, calcite and kaolinite cement below 2140 m. Rare dolomite at 2075 m, trace chert and volcanics at 2115 m. -  -  2250 to 2605 m Interbedded Shale and sandstone with minor siltstone. Shale grey, black, red, white, micaceous, blocky to platey, silty or calcic in part, some chert pebbles and quartz grains, occasionally carbonaceous, waxy at 2565 m. Sandstone black, grey, grey green, very fine to fine grained, calcic and silicic cement, feldspar cement at 2550 m, sub-angular to sub rounded, occasional chert clasts, fair to well sorted, no to poor porosity, occasionally grades to siltstone, maroon sandstone with feldspar crystals and shale from 2525 to 2530 m, feldspar in the sandstone from 2530 to 2587 m. Siltstone grey, micaceous, blocky, argillaceous, grades to very fine grained sandstone and silty shale. -  -  -  2605 to 2915 m Interbedded shale and pebbly sandstone. Shale brown grey, grey, black, green grey, maroon, red, silty in part grading to chert, blocky to platey, micaceous and carbonaceous in part, some calcite. Sandstone grey, green, brown grey, very fine, medium and coarse grained, poor to fair sorting, sub-angular to sub rounded, calcic and silicic cement, chloritic in part, grades to conglomerate, argillaceous and silty in part, trace feldspar at 2820 and 2870 m. -  -  -  2915 to 3000 m Shale and igneous rock. Shale grey, green grey, red brown, purple grey, black, 10% claystone, blocky to subblocky, micaceous, slightly carbonaceous, grades to chert at 3000 m. Igneous rock very dark green to black, feldspar crystals, chloritic, magnetic, calcic, brittle. -  -  3000 to 3082 m Shale and chert with minor igneous rock. Shale red brown, grey, claystone is light grey, silicic in part grading to chert. Chert black, grey, green grey, green, orange, pink, micaceous and feldspathic in part, grading to claystone, slightly argillaceous in part, trace pyrite. Igneous rock green, black, red brown, dark purple, calcite crystals and inclusions, very fine to finely crystalline, brittle. -  -  -  3082 to 3170 m Chert with minor shale. Chert grey, green, red brown, dark purple, black, red, mottled, rust, calcite and dolomite partings and inclusions, argillaceous, grading to very silicic shale, micro crystalline to very finely crystalline, appears brecciated and weathered in part (could be siliceous igneous rock), rare mica. Shale - as above grading to claystone, red brown. -  3170 to 3250 m  293  Siliceous ooze, limestone, chert, claystone and minor igneous rock. Siliceous ooze white, siliceous to very siliceous, grading to chert, crypto to micro crystalline. Chert buff to brown, grading to claystone. Claystone light green grey, mottled purple pink, siliceous grading to chert, platey to subblocky, slightly calcic. Shale red brown, light green grey, platey to sub blocky, slightly carbonaceous and calcic, micaceous in part. Igneous rock dark purple, black, dark green, calcite and dolomite crystals and inclusions, micro crystalline to finely crystalline to medium, trace mica, some chlorite, brittle. -  -  -  -  -  3250 to 3324 m Igneous rock and minor chert. Igneous rock as above, mottled red brown and purple volcanic rock, cherty and clayey grading to chert and claystone, brecciated in part, feldspathic; or purple and maroon, tuffaceous, cherty and clayey; or mottled purple, orange and green, red brown, feldspathic, siliceous and clayey grading to chert and claystone. Chert as above, mottled, grading to claystone, igneous in part, feldspathic. -  -  294  SECTION 25 - CHILCOTIN B-22-K WELL Subsurface stratigraphic section derived from well log data and analysis of cuttings. Descriptions start at the top of the well. 0 to 580 m  Volcanics - Basalt black, dark grey to medium grey, vesicular, vesicles are lined by green epidote or chlorite, rarely scoriatious, micaceous, calcitic, occasional rusty blebs. Felsic volcanics vuggy, pink, white, medium brown. At 542 m is a white felsic rock with hornblende crystals, biotite and quartz. -  -  580 to 600 m  Shale - black to dark grey.  600 to 720 m  Shale and lesser sandstone. Sandstone - light to medium brown, minor carbonaceous material. Shale - black. Minor red volcanics. 720 to 770 m  Sandstone and lesser shale. Sandstone - medium brown, minor carbonaceous material, quartzose. Shale - black, carbonaceous. 770 to 785 m  Sandstone with very minor shale and limestone. Sandstone - grey brown, carbonaceous, quartzose. Shale - black to dark grey, carbonaceous. 785 to 810 m  Sandstone with lesser shale. Sandstone - medium brown, minor carbonaceous material, quartzose. Shale - black, carbonaceous. 810 to 840 m  Shale with minor sandstone. Shale - black, carbonaceous. Sandstone - medium brown, minor carbonaceous material, quartzose. 840 to 925 m  Sandstone with lesser shale. Sandstone - very fine grained, medium brown to dark brown, dark green brown, pale brown, pink, green, minor carbonaceous material. Shale - black to dark grey, carbonaceous. 925 to 940 m carbonaceous. 940 to 1060 m  Sandstone - medium brown, very fine grained, moderately  Sandstone with minor shale. Sandstone - medium to dark brown, carbonaceous. Shale - black, carbonaceous.  very fine grained,  1060 to 1210 m Shale with minor sandstone. Shale - black, grey to dark grey, carbonaceous. Sandstone - brown, very fine grained, carbonaceous. 1210 to 1300 m Sandstone - dark brown, white to cream, pale brown, very fine grained, quartzose in part, carbonaceous.  295  1300 to 1600 m Interbedded sandstone and shale. Sandstone - brown, grey, very fine grained, carbonaceous and quartzose in part, very micaceous in part. Shale - medium to dark grey, black, carbonaceous. 1600 to 1660 m Shale - black to dark grey, carbonaceous. 1660 to 1940 m Sandstone and lesser shale. Sandstone - brown, carbonaceous in part, glauconite at 1872 m. Shale - black to dark grey, carbonaceous. 1940 to 2030 m Shale with lesser sandstone. Shale - black to dark grey, carbonaceous. Sandstone - pinkish, brown, red, maroon, cream, moderately carbonaceous in part. 2030 to 2090 m Sandstone with lesser shale. Sandstone - cream, very fine grained. Shale - dark grey, carbonaceous. 2090 to 2175 m Shale with lesser sandstone. Shale - black to dark grey, brown grey, dark brown, mottled, carbonaceous. Sandstone - pale brown to cream, very fine grained, minor carbonaceous material, quartzose. 2175 to 2270 m Sandstone with lesser shale. Sandstone - cream, medium grey brown, very fine grained, minor carbonaceous material in part. Shale - dark grey to black, carbonaceous. 2270 to 2320 m Shale with very minor sandstone. Shale - dark grey to black, carbonaceous. Sandstone - cream, as above. 2320 to 3765 m Volcanics - black, dark grey, pink, brown, maroon, pale grey, red, green, white; fine to very fine grained; feldspar porphyry from 2720 to 2970; vesicular in part, fragmental in part with red fragments in a green matrix. At 2630 m are granitic fragments and quartz. Augite (?) porphyry at 3100 m. Rusty from 3207 to 3765 m. White quartz fragments from 3545 to 3585 m, then intergrown quartz carbonate to 3667 m. Ends at 3765 m with porphyritic, amygdaloidal maroon volcanics.  296  SECTION 26 - POTATO RANGE (92N/9; UTME 405.250 UTMN 5718.500) This is a fairly continuous section of bedded sandstone with minor shale and conglomerate, measuring 417.5 m in total. Bedding varies from 086/16SE to 055/25SE to 035/25SE to 040/16SE to 067/LOSE up section. Starting elevation for the measured section is just above tree line at 1560 m (5148 ft). This section includes the Relay Mountain Group - units 9 (Oxfordian to Berriasian) and 10 (Berriasian to Barremian) of map 5-1968 by Tipper (G.S.C. paper 68-33). - 0 - 40 m  Base of section. Fine grained, dark grey/green sandstone. Weathers dark rusty brown. Highly fossiliferous - bivalves and belemnites, belemnites have been replaced by calcite, bivalves are mainly moulds/casts. Contains limestone clasts which are brecciated with pieces of sandstone. Two sets of slickensides are present on the bedding surfaces. Possible bedding 080/25SE and 086/16SE. As you proceed upsection the sandstone becomes paler brown and less fossiliferous, it is still fine grained but now weathers medium brown/grey. Sandstone is now thinly bedded with beds 1-2 cm wide which are highly fractured. - 40 - 50 m  Recessive covered area.  - 50- 53 m  Fine grained sandstone, greenish brown in colour, weathers pale brown. Well sorted, slightly fossiliferous. Fairly soft, strongly fractured sandstone. Bedding 055/25SE. - 53 - 63 m  Recessive covered area.  - 63 - 68 m  Medium to coarse grained sandstone, greenish in colour with a white clayey matrix. Weathers pale brown. Massive. - 68 - 73 m  Very fine grained black, argillaceous shale. Weathers dark grey to brown. Very recessive. Contains carbonized wood fragments and seeds. Bedding 042/12SE. - 73 - 81 m  Very coarse grained sandstone, grey/green in colour with black, green and grey fragments. Weathers medium grey. Contains organic matter. - 81 - 91 m  Coarse grained sandstone with white and green fragments. Weathers pale brown, weathers rounded. Massive. Bedding 035/25SE. - 91 - 99 m sorted. -99- 105 m  Fine grained sandstone, pale grey in colour. Weathers creamy. Well  297  Medium grained sandstone, green in colour. Weathers rusty brown. Bedding 039/22SE. - 105 - 111 m  Grades up to medium grained sandstone which weathers dark rusty brown. This sandstone contains pebbly beds about 3cm wide. Pebbles are fairly well rounded and are aligned parallel to bedding. Pebbles average lcm in diameter and are composed mainly of light and dark grey chert. - 111- 112 m layers. - 112 - 114 m - 114 - 116 m - 116 - 118 m - 118 - 121 m  Grey limestone. Weathers dark grey to white. Occurs in thin crinkly Medium grained sandstone. Coarse grained sandstone. Medium grained sandstone. Coarse grained sandstone.  - 121 - 122 m  Coarse grained arkosic sandstone, white in colour. Weathers in creamy/brown stripes. - 122 - 152 m Recessive covered area. - 152 - 157 m  Conglomerate. Massive. Weathers dark grey/rust. Clast supported with a coarse grained sandstone matrix. Well rounded to subrounded pebbles which vary in size from 1-15cm in diameter. Clasts are composed mainly of black or pale grey feldspar phyric volcanics with minor amounts of grey chert and granitic clasts. Some chert clasts look as though they may be full of silicified coral stems. - 157 - 158 m - 158 - 162 m  Coarse grained sandstone. Conglomerate.  - 162 - 163 m  Medium grained, bright green sandstone. Weathers grey green. Very hard. Glauconitic ? - 163 - 166 m  Interbedded medium grained, arkosic sandstone and dull grey green, very fine grained, hard sandstone. Arkosic sandstone Weathers pale creamy/brown, other weathers grey brown.  298  - 166 - 181 m - 181 - 182 m  Greywacke, grading from coarse to medium to fine grained upsection. Conglomerate.  - 182 - 212 m  Medium grained sandstone. Weathers pale brownish grey. Highly fossiliferous, packed full of shells with some belemnites. Shells are up to 10cm long (Buchia ?). Sandstone is interbedded with thin, crinkly layered limestone beds about 20cm thick. Sandstone has non-fossiliferous and fossiliferous beds. Non-fossiliferous beds are 0.5-1.0m thick, fossiliferous beds are 0.3-0.5m thick. Also interbedded occasionally with bright green, fine grained sandstone beds. Bedding 040/16SE. - 212 - 227 m  Medium grained sandstone, creamy in colour. Weathers pale brown. Well sorted, massive. Grades up to fossiliferous beds. Alternating non-fossiliferous (0.5m thick) and fossiliferous (0.3m thick) beds. Fossiliferous beds have perfectly flat bases. - 227 - 257 m  Grades up to white, medium grained, dark green brown weathering sandstone. Fossiliferous, has smoother shells and some of the original shell material. Contains belemnites up to 3cm in diameter. - 257 - 272 m - 272 - 282 m sandstone.  Grades up to dark green, fine grained, brown weathering sandstone. Grades up to white/green, medium grained, creamy weathering  - 282 - 290 m  Grades up to medium brown, fine grained, brown weathering sandstone interbedded with very coarse grained pebbly sandstone which weathers dark rusty brown. Pebbles are sub-angular and a maximum of 2cm long. Pebbles are mainly porphyritc volcanic or fine grained and grey. Pebbly beds are 3m thick, nonpebbly beds are lm thick. Bedding 067/10SE. - 290 - 294 m - 294 - 298 m  Medium grained, white green sandstone. Medium grained, dark green sandstone.  - 298 - 308 m  Recessive area with fine grained, very dark brown sandy shale with white lines. Weathers black. Contains carbonaceous material. - 308 - 310 m  Very coarse grained, white green sandstone. Weathers grey/brown. Grades up to white, fine grained sandstone which weathers creamy and contains plant fossils and other organic material.  299  - 310 - 310.5 m Coarse grained, dark grey arkose. Weathers dark grey brown. - 310.5 - 314.5 m Very coarse grained and fine grained white green sandstone with interbedded fine grained, grey siltstone layers 10cm wide. - 314.5 - 318.5 m (On the opposite slope can see alternating dark and light beds each about 4m thick) Dark green greywacke. - 318.5 - 323.5 m White, fine grained sandstone grades up to matrix supported conglomerate. Pebbles are up to 25cm long, matrix is very coarse grained white green sandstone. - 323.5 - 333.5 m Alternating beds of matrix supported conglomerate and coarse grained white green sandstone. - 333.5 - 343.5 m Grades up to very dark grey, fine grained, dark rusty brown weathering sandstone. Very hard, has alternating beds of fine grained and pebbly sandstone. - 343.5 - 348.5 m Dark green, sheared greywacke. - 348.5 - 356.5 m Soft, brown medium grained sandstone. - 356.5 - 359.5 m Dark grey, fine grained, rusty brown weathering sandstone. - 359.5 - 379.5 m Recessive covered area. - 379.5 - 380.5 m Coarse grained, green greywacke. Weathers crumbly. - 380.5 - 381.5 m Fine grained, grey, very dark brown weathering sandstone with belemnites. - 381.5 - .91.5 m Recessive covered area. - 391.5 - 392.5 m Fine grained, dark grey, dark brown weathering sandstone. - 392.5 - 407.5 m Recessive covered area.  300  - 407.5 - 417.5 m Fine grained, grading to coarse grained white sandstone. Weathers creamy. Interbedded with dark green, medium grained sandstone. At the top the white sandstone is coarse grained and has cross-bedding. The (white) sandstone contains some organic matter along bedding planes (twigs etc.), also has some very rusty patches, the top of the section has gossanous soil.  301  SECTION 27 - RIDGE WEST OF MOUNT TATLOW (920/5; UTME 436.690 UTMN 5793.650) Section measured through Taylor Creek Group sediments, starting at elevation 7020' at the top of the section and measuring down section through almost vertical beds. Bedding 086/84S. - 0 - 3.25 m  Pebble conglomerate. Weathers dark grey brown to rust, fresh is dark grey. Clast supported with rounded to sub-angular clasts from 0.5 to 6 cm in diameter, average 2 cm. The matrix is fine to medium grained sandstone, varies along the base of the bedding plane. Clasts are composed of 80% chert with black veins (banded black, black, grey, white; 3% granitic, 5% white quartz, 6% grey siltstone, 4% green siltstone, 2% lithic. - 3.25 - 11.85 m Interbedded sandstone and shale. Sandstone weathers medium grey, fresh is dark brownish grey, medium grained, composed of chert and quartz. Well bedded with individual beds 0.3 to 0.75m thick. Shale weathers black, fresh is black/brown. Well laminated with planar lams 1mm thick. Fairly fissile, well bedded with individual beds 0.40 to 0.70m thick. Abrupt changes to sandstone. - 11.85 - 13.1 m Repetitive fining upward sequence of conglomerate siltstone and sandstone. Individual cycle 0.60m thick with basal conglomerate 10 to 15 cm thick, overlying siltstone 0 to 3 cm thick and upper sandstone 45 cm thick. The conglomerate is clast to matrix supported with clasts from 0.5 to 1.5 cm in diameter in a fine grained sandstone matrix, clasts composition is as above. Siltstone is black and argillaceous filling in depressions in the top of the conglomerate. Sandstone is fine grained, massive and has siltstone lenses within it (same as above). Towards the top of this unit is a dark brown limey bed. Underlain by sandstone with small (3mm diameter) rounded to sub-angular clasts The limey bed is made up of concretions parallel to bedding. The concretions are 10 to 30 cm long and elongate oval in shape, some concretions scour into the underlying sandstone with scours 2 cm deep. This whole outcrop is resistant and cliff forming and weathers orangy brown. - 13.1 - 18.6 m  Abrupt change to pebble conglomerate. Clasts vary from 0.4 to 5 cm in diameter, composed mainly of chert. Clast supported with a matrix of fine grained sandstone. Appears bimodal with clasts averaging 0.8 cm or 2 cm in diameter. - 18.6 - 30.2 m  Abrupt change to interbedded sandstone and shale. Shale is directly below the conglomerate, black, fissile, gritty, some plant material; the first bed is 10 to 15 cm thick, other beds vary from 30 to 50 cm thick. Sandstone is fine grained, pale grey, laminated with lams grouped 3mm thick. This sandstone grades to darker grey, dirty sandstone which is very crumbly/friable. The darker sandstone is greenish grey on fresh surface. Individual sandstone beds vary from 0.40 to 0.70 cm thick. -30.2-35.5 m  Abrupt change to Coarse grained sandstone with 5% clasts grading to matrix supported conglomerate. Sandstone weathers medium brown to rust, fresh is  302  dark grey, some clasts are aligned parallel to bedding. Conglomerate has 20 to 25% sub-rounded to sub-angular clasts from 0.4 to 7 cm in diameter, mainly chert. Clasts are aligned parallel to bedding in most places. Matrix is medium grained sandstone. There is another limey bed here 20 cm thick, again this is medium grained sandstone with small clasts (5mm in diameter) and limey cement?. - 35.5 - 56.85 m Abrupt change to interbedded sandstone and shale. Directly below the conglomerate is shale - black, fissile/highly fractured, manganese staining. Changes abruptly to fine grained, pale grey weathering sandstone, fresh is also pale grey - very hard. Rare grouped laminations, this sandstone bed is 0.60m thick. The rest of this unit is interbedded sandstone and shale. Shale is same, sandstone weathers medium to light grey, fresh is darker grey with white specks, coarse to fine grained, friable/fractured up. Has some siltstone blebs and carbonized wood fragments. Shale beds are 0.6 to lm thick, sandstone beds are 0.15 to 0.40m thick. Some slickensides are visible in the shale beds, appear to be parallel to bedding. The interbedded sandstone and shale are cut by a pale brown weathering sill - feldspar phyric with quartz and hornblende in a fine grained, pale grey matrix. 50 35% feldspar, max. 2 x 5 mm; 3% quartz, rounded 2 mm in diameter; and 5% hornblende and minor biotite. Feldspars glom together in some places. Very sharp contact with sediments which appear unaffected. - 56.85 - 58.35 m Siltstone, weathers medium greenish grey, fresh is dark grey. Highly fractured up, broken into small pieces ( <1cm) at surface. - 58.35 - 61.05 m Fairly abrupt change to fine grained sandstone - fresh is medium grey, weathers darker grey or rusty brown. Also highly fractured. Occasional black laminations lmm wide parallel to bedding. Appears dirtier and less well sorted at the base of the bed. - 61.05 - 63.85 m Abrupt change to fine grained, pale grey sandstone, weathers brownish grey to rust. Very flaggy - layers 3 to 4 mm thick. Finely laminated with black lams less than 1 mm thick spaced 2 mm apart, lams are parallel to bedding. - 63.85 - 65.85 m Abrupt change to siltstone, weathered and fresh surfaces are black. Highly fractured and recessive. - 65.85 - 68.85 m Abrupt change to fine grained sandstone, weathers brownish grey to orange rust, fresh is light grey with black speckles, very hard. Towards the base the sandstone is medium grained with black siltstone blebs and clasts 2mm in diameter. At the base of the bed is laminated, cross-bedded sandstone. Laminations are 1mm thick cross-beds are 1 x 2 cm, also silty interbeds 4 cm thick. At the very base bedding is wavy. Also a lensoid, dark brown limey, bed 10 cm thick. The base of the bed has lode casts of sandstone into siltstone and burrows? - 68.85 - 70.85 m Abrupt change to shale, weathered and fresh surfaces are black. Highly fractured/ fissile. Recessive.  303  - 70.85 - 78.25 m Abrupt change to interbedded sandstone and shale/siltstone. Shale/siltstone weathers dark greenish grey, fresh is dark grey, very friable splinters up into 5mm square pieces. Beds are 0.80m thick. Sandstone weathers light grey brown, fresh is medium grey, fine to medium grained, interlaminated with grey siltstone laminations and blebs. Beds vary from 0.20 to 0.40 m thick. The siltstone lams within the sandstone have white blebs up to 3 mm in diameter, also leaf and twig fossils. This whole outcrop is highly fractured and crumbly, but sandstone is resistant in spots (not the whole sandstone bed). Wavy bedding. - 78.25 - 82.5 m Abrupt change to fine grained sandstone, weathers grey green, fresh is grey/brown (looks cherty). Laminated in places with siltstone lams 4 mm thick parallel to bedding or slightly wavy. Minor interbedded siltstone, this siltstone is black, slightly gritty, weathers brown to black, has carbonized twigs. These siltstone beds are lensoid and 15 cm thick. - 82.5 - 85.5 m  Abrupt change to fine grained sandstone, weathers light brown grey, fresh is light grey with some blebs of siltstone (ripups ?). Fractured up into large blocks. Has 1% chert clasts 6 mm in diameter at the base. - 85.5 - 89.65 m Abrupt change to interbedded sandstone and shale. Shale weathers dark grey green, fresh is dark grey, slightly gritty, highly fractured, each bed is 0.30 to 0.60 m thick. Sandstone is fine grained, weathers greenish grey, fresh is medium grey, fairly hard, alternating light and dark green bands 1mm thick, each sandstone bed is 0.40m thick, fractured up. Towards the base of the sandstone beds the lams show wavy bedding with undulations up to 1cm. - 89.65 - 91.5 m Sandstone, medium grained, granular, weathers greenish brown, fresh is darker green grey. Has some small (3mm diameter) scattered clasts. Less well lithified than above sandstones. Has limey concretions 15 cm wide by 20 to 30 cm long within - look the same as the dark brown limey sandstone seen earlier. Towards the base of the bed the sandstone grades to fine grained grey, hard sandstone as above but has no laminations, has a 2cm thick bioturbated horizon of dark grey to black silt with sandy burrows. - 91.5 - 93 m Recessive.  Shale, weathered and fresh is dark grey, highly fractured/splintered.  - 93 - 94.55 m  Abrupt change to fine to medium grained sandstone, weathers brown green, less well lithified, granular. Has limey concretions same as above. - 94.55 - 97.35 m Abrupt change to black shale. - 97.35 - 99.15 m Abrupt change to medium grained, granular sandstone. Weathers light grey/green, fresh is greenish with alternating dark grey and pale grey  304  laminations, fairly hard. Towards the base of the bed is a pebble rich layer 25 cm thick with pebbles 0.2 to lcm in diameter. - 99.15 - 105.15 m Abrupt change to fine grained sandstone, weathers grey/brown, fresh is pale grey, few black siltstone laminations 3 mm thick. Highly fractured into thin layers 1 to 3cm apart, slightly micaceous (biotite or phlogopite). - 150.15 - 152.05 m Sediments are cut by a sill - hornblende, feldspar phyric. Tiny acicular hornblendes make up 10% of the rock. Weathers cream to rusty orange, fresh is pale grey with small, white carbonate blebs. Seds. appear unaffected by the sill. - 152.05 - 153.25 m Abrupt change to fine grained sandstone, weathers light brown/orange to brown grey, fresh is dark grey brown. Slightly micaceous with less than 1% muscovite. Carbonized wood fragments occur at the base of the bed. Well lithified but fractured into blocks. - 153.25 - 160.25 m Abrupt change to interbedded shale (70%) and fine grained sandstone (30%). Shale weathers black, fresh is dark grey, highly fractured into 6mm angular pieces. Sandstone weathers dark brownish green, fresh is dark grey, gritty, micaceous with tiny pieces of organic matter. Highly fractured into 1 to 2 cm pieces. Weathers rounded. Shale beds are lm thick, sandstone beds 0.30m. - 160.25 - 162.8 m Fine to medium grained sandstone weathers medium green/grey to orange, fresh is medium grey, granular. Rare siltstone blebs (rip ups?). The top of the bed is thinly bedded/fractured into layers lcm thick. Slightly micaceous. In the middle of the sandstone is a dark brown limey bed 0.35 to 0.40m thick of fine to medium grained sandstone with carbonized wood fragments and mica, fresh surface is dark grey, laminations are visible on the weathered surface as the carbonate weathers out. Fizzes strongly in 10% HC1. - 162.8 - 177.95 m Abrupt change to recessive interbedded sandstone and shale. Shale weathers black, fresh is also black, fractured into 0.5 to 3cm pieces. First bed below overlying sandstone is a shale bed 20 cm thick, other shale beds vary from 0.3 to 0.7m thick. Sandstone weathers dark green brown, fresh is dark green or black. Appears to be intermixed black siltstone and green sandstone in swirls (bioturbated?). Fractured up into 1 to 5 cm pieces. No mica. Towards the top is a 0.60m thick bed of coarse grained sandstone that weathers medium grey, fresh is green grey, composed of chert and quartz with minor muscovite. Harder, more competent rock. Towards the base the sandstone fines a little and no longer appears bioturbated. - 177.95 - 181.25 m Abrupt change to medium grained sandstone, weathers medium greyorange. Dense hard rock of chert and quartz, no mica. At the base is a discontinuous lens of shale and limey mud lm thick. - 181.25 - 182.1 m  305  Abrupt change to fine grained sandstone, weathers dark brown, fresh  is black, gritty, micaceous, some patches of bioturbation. Highly fractured/splintery.  - 182.1 - 182.8 m Coarse grained sandstone, weathers pale brown-orange, fresh is light grey, occasional dark grey chert pebbles 5mm in diameter, no mica. - 182.8 - 184 m Abrupt change to interbedded shale and fine grained sandstone. Shale, black, highly fractured. Sandstone weathers brown, fresh is dark grey, highly fractured. Shale beds are 0.30 to 0.50 m thick, sandstone 0.15 m thick. - 184 - 184.85 m Changes abruptly to medium grained sandstone, weathers medium green grey, fresh is medium green, slightly micaceous ( < 1%). Interbedded with dark brown weathering limey beds, fresh id dark grey, very fine grained, laminations are visible on the weathered surface. Limey beds are 10 to 20 cm thick. - 184.85 - 189.45 m Abrupt change to shale, weathers dark brown, fresh is black, highly fractured, splintery, some mica. - 189.45 - 190.1 m Changes abruptly to coarse grained to very coarse grained sandstone with grains from 1 to 3mm average, maximum 1cm in diameter. Grades from sandstone to pebble conglomerate, mainly sub-angular to sub-rounded chert pebbles. Discontinuous lens of conglomerate (channel?). - 190.1 - 193.6 m Abrupt change to fine grained sandstone, weathers dark grey to grey brown, gritty, highly fractured, some mica. Towards the base are dark brown weathering limey concretions, fresh is dark grey, made of medium grained sandstone with mica, 15 to 25 cm in diameter. At the base is coarse grained sandstone. - 193.6 - 200.5 m Abrupt change to matrix supported pebble conglomerate, weathers dark brown, matrix is dark brown grey coarse to medium grained sandstone with very little mica. Clasts are rounded to sub-angular and vary from 0.3 to 2 cm in diameter, making up 10 to 15% of the rock. Clasts are composed of 80% black, grey, white or veined chert, 15% grey/black siltstone and 5% white quartz. The number of pebbles decreases towards the base of the bed to 3%. Pebbles are aligned parallel to bedding, especially near the base. [- 5m  Sediments are cut by a dyke - feldspar, hornblende? phyric, weathers creamy to orange brown, fresh is pale grey with white feldspar and dark green chloratized mafics. Feldspars are crudely trachytic.] - 200.5 - 203.5 m Abrupt change to shale, black, weathers dark brown, highly fractured, - 203.5 - 208.5 m Abrupt change to very fine grained, pale grey sandstone (looks cherty). Weathered surface has white speckles, see siltstone blebs ( <5mm  306  diameter), highly fractured. Base of bed is laminated with lams 1 to 2 cm apart, some bioturbation and burrows. Slightly wavy bedding, load structures - tiny ball and pillows. - 208.5 - 251.5 m Gradational change to interbedded siltstone and fine grained sandstone. Siltstone weathers dark grey brown, fresh is dark grey, highly fractured/splintery. Sandstone weathers dark brown, fresh is dark grey, highly fractured, some siltstone rip up clasts at the base of beds. Individual sandstone beds are 0.25 to lm thick, siltstone beds are 0.25 to 0.3m thick. - 251.5 - 266.5 m Abrupt change to interbedded black and dark green shale. Black shale weathers dark brown, slightly gritty, highly fractured/splintery, beds from 1 to 1.2m thick. Green shale weathers dark green to brown, highly fractured/splintery, beds from 0.2 to 0.8m thick. in the centre of the outcrop is a bed of fine grained grey sandstone 0.60m thick that weathers light grey, fresh is also light grey, highly fractured. Three meters above the base is a fine to medium grained sandstone bed that weathers light grey, granular, micaceous, 2m thick with thin interbeds of green shale 15 cm thick at the top and bottom. - 266.5 - 272.9 m Abrupt change to very coarse grained sandstone grading to clasts supported pebble conglomerate then back to very coarse grained sandstone. Weathers white to orangy brown, fresh is white, mainly chert and quartz grains with minor mica. The conglomerate has a matrix of very coarse grained sandstone with sub-angular to rounded pebbles from 0.5 to 3 cm long, mainly chert and quartz with lesser granitic clasts and < 1% dark brown feldspar and mafic phyric rounded, soft volcanic? clasts 1cm in diameter and some white, soft, fine grained, feldspar phyric clasts. - 272.9 - 279.9 m Abrupt change to shale, weathers black to dark brown with manganese staining, fresh is black, highly fractured, splintery. Towards the base of the bed is a fine to medium grained sandstone lens 60 cm thick, granular, dark grey green sandstone that weathers medium grey, micaceous, fairly hard. - 279.9 - 297.3 m Abrupt change to interbedded fine grained green sandstone, medium grained grey sandstone and shale. Green sandstone is highly fractured and micaceous; grey sandstone weathers medium grey and is also micaceous; shale is black and highly fractured. Green sandstone beds are 0.5 to 4m thick; grey sandstone beds lm thick; and shale beds 0.1 to 0.6m thick. - 297.3 - 342.3 m Abrupt change to shale, recessive and partially covered. Shale weathers dark brown, fresh is black, highly fractured, slightly gritty, splintery. Thin white planar laminations 0.1 to 1 mm thick. Minor interbeds of fine grained, pale grey sandstone, weathers pale grey also, highly fractured, some mica, beds 0.50m thick. Towards the base limey concretions occur within the shale. Concretions weather dark brown, fresh is medium grey, vary from 5 to 40 cm long, rectangular to elongate oval in shape, traces of plants on some concretion surfaces. - 342.3 - 359.5 m  307  Covered, probably shale. - 359.5 - 365.5 m Abrupt change to pebble conglomerate, clast/matrix supported. Weathers grey to orangy brown, matrix is fine to medium grained with sub-rounded to rounded pebbles 0.3 to 4 cm in diameter. Clasts are composed of 80% black, grey, white and veined chert; 9% fine grained, soft, pale brown clasts; 2% fine grained sandstone, 7% black siltstone; and 2% white quartz. Pebbles decrease in abundance downwards the lowest lm has only 1% pebbles. One very rusty patch at the base. - 365.5 - 385 m Abrupt change to interbedded black and green shale and sandstone. Black shale weathers black, highly fractured/splintery beds 0.70m thick. Green shale weathers dark olive green, highly fractured/splintery, slightly gritty, beds 0.50m thick. Sandstone is fine to medium grained, granular, weathers pale green/grey, fresh is pale grey, micaceous, beds 0.50m thick, fine sandstone beds are highly fractured. - 385 - 410.5 m Covered, probably shale. - 410.5 - 419.5 m Fairly abrupt change to dark grey to black shale, highly fractured, interbedded with dark green, fine grained sandstone, also highly fractured. - 419.5 - 423.8 m Abrupt change to very coarse grained to coarse grained pebbly sandstone, weathers rusty brown, pebbles are sub-rounded to rounded and vary from 1.2 to 6mm in diameter, same composition as above. This outcrop is very blocky and fractured. - 423.8 - 429.2 m Abrupt change to shale, black, slightly gritty, highly fractured/splintery. - 429.2 - 432.55 m Abrupt change to coarse grained sandstone, weathers light grey, fresh is light grey green, hard, composed of chert and quartz with minor mica. - 432.55 - 469.55 m Abrupt change to interbedded shale and fine grained sandstone. Shale is dark grey to black, highly fractured/splintery, slightly gritty, beds 1.5m thick. Sandstone is dark green on both fresh and weathered surfaces, micaceous, highly fractured, beds 0.60m thick. Lower in the sequence both sandstone and shale are finely laminated with lams 0.2 to 1mm thick, beds are also more narrowly interbedded with shale beds 0.30m thick and sandstone beds from 0.10 to 0.35m thick. Sandstone beds are internally thinly bedded with slightly wavy beds 0.5 to 1 cm thick. - 469.55 - 471.55 m Abrupt change to coarse grained sandstone, weathers pale brown to orange, fresh is grey green with 5% oval clasts 5mm long crudely aligned parallel to bedding.  308  - 471.55 - 499.05 m Abrupt change to interbedded green sandstone and shale same as above. In the centre of this unit are dark brown weathering limey concretions, fresh is dark grey, fine grained, rounded, vary from 15 to 25 cm in diameter. Towards the base of this sequence is a feldspar-quartz phyric sill lm thick, weathers white. - 499.05 - 509.55 m Covered, probably shale. - 509.55 - 526.45 m Matrix supported pebble conglomerate, weathers creamy to orange, matrix is medium to coarse grained grey white sandstone. Pebbles are angular to rounded, small ones are more angular, and vary from 0.3 to 2 cm long, same composition as earlier. Becomes clast supported towards the base. Outcrop is fractured up into large blocks. - 526.45 - 537.45 m Interbedded shale and sandstone. Shale is black, highly fractured/splintery, beds 0.20 to 0.60m thick. Sandstone is fine grained, grey, weathers dark grey green, micaceous, fractured into small pieces 2cm wide. - 537.45 - 546.75 m Coarse grained sandstone, weathers creamy brown, fresh is light grey, has 1% pebbles 1cm in diameter, no mica. - Section continues along the ridge as alternating shale and coarse grained sandstone.  309  SECTION 28 - VICK CREEK (920/12 UTME 450.750 UTMN 5716.500) This section was measured through sandstone interbedded with minor shale in the Kingsvale Group (Cenomanian). Total thickness of the measured section is 507.25m. Starting elevation beside the river was 1150m. Bedding varies from 090/30N to 144/50NE to 012/29SE to 162/15NE up section.  - 0 - 93m (Base of section) Covered. - 93 - 95.5 m  Greywacke, coarse grained, dark greenish grey, weathers dark to medium grey, massive. Sample J90-012-01. - 95.5 - 100 m  Covered. Recessive area, may be shale as this outcrops just below the overlying Sandstone. Shale is black, fine grained, highly fractured. Sample J90-01202. - 100 - 104.5 m Greywacke, very coarse grained, pebbly, dark grey green, weathers medium grey, pebbles are, rounded, composed mainly of grey or green chert, 1cm diameter. Sandstone is mainly quartz. Sample J90-012-03. Grades up to 1.5m thick bed of very coarse grained Greywacke, friable. - 104.5 - 113.5 m Covered. - 113.5 - 118.75 m Greywacke, very coarse grained, pebbly, dark grey green, weathers medium grey and crumbly, pebbles are a max of 4mm in diameter. Individual beds grade from pebbly to very coarse grained, beds are 20cm thick. - 118.75 - 128.75 m Covered. Recessive area, may be mudstone as this outcrops beneath the overlying Greywacke unit. Mudstone, very fine grained, medium grey, weathers white to rusty, some organic material. Sample J90-012-04. - 128.75 - 131.75 m Greywacke, fine grained , medium grey, weathers medium grey also. Grades up to coarse grained Greywacke. There is a repeating sequence of graded beds each 0.30m thick. Fine grained Greywacke is hard, coarse grained tends to be more friable. Fine grained Greywacke is jointed giving layers 1 - 2 cm thick. Sample J90-012-05. - 131.75 - 158.75 m Covered. Recessive area with one outcrop of siltstone, fine grained, medium grey, weathers rusty, has organic matter, highly fractured. Sample J90-01206. - 158.75 - 160.15 m  310  Greywacke, medium grained, white/green, weathers pale grey. Vertically jointed. Overlain by coarse grained, dark grey/green Greywacke, weathers dark grey/rust. - 160.15 - 163.75 m Covered. - 163.75 - 167.25 m Sandstone, fine grained, white, weathers creamy, massive, well sorted, grades up through medium grained to coarse grained Greywacke. Greywacke is dark grey green, weathers grey/brown, has a few rounded pebbles 7mm in diameter. - 167.25 - 182.25 m Covered. - 182.25 - 192.75 m Breccia, fine grained, matrix is dark grey green with feldspar. Clasts are angular, maroon or green, vary from 0.02 - 4m long. Breccia weathers purplish grey, and has some patches of coarse grained, feldspar porphyritic volcanic (clasts ?), feldspar phenos in the patches are 3mm square. Outcrop is very crumbly, highly fractured, calcite in and along fractures. weathers rusty in blebs. - 192.75 - 198.75 m Covered. Recessive area of volcanics, soft, fine grained, maroon/grey. - 198.75 - 209.25 m Sandstone, coarse grained, white/green, weathers creamy, fairly soft (crumbly) but forms cliffs. Cross bedding outlined by darker layers, occassional rounded pebbles 1cm in diameter, rusty layers and blebs (layers 25cm thick, blebs 10cm in diameter) that contain organic matter. Weathers into large rounded holes as though large concretions had fallen out. Samples J90-012-08,09. - 209.25 - 221.25 m Greywacke, fine grained, dark grey/purplish, feldspar crystals on weathered surface, weathers grey brown with rusty blebs. Grades up to coarse grained Greywacke with angular and rounded green porphyritic fragments up to 2cm long. (looks like lower breccia) - 221.25 - 222.75 m Sandstone, coarse grained to very coarse grained, white, weathers creamy with rusty blebs, in very coarse grained Sandstone see black or maroon fragments. Some quartz, clayey matrix. - 222.75 - 230.25 m Covered. - 230.25 - 231.15 m Sandstone, pale grey, very fine grained, weathers white, massive, highly fractured. Sample J90-012-10. - 231.15 - 232.85 m Sandstone, very fine grained, medium brown, weathers pale brown, massive, highly fractured. Sample J90-012-11.  311  - 232.85 - 233.25 m Sandstone, very fine grained, white, weathers creamy with a powdery white coating, massive, pinches and swells from 0.15 to 0.40 m thick along bedding. (Ash?) Sample J90-012-12. - 233.25 - 235.75 m Sandstone, very fine grained, creamy, weathers pale brown, massive, highly fractured. - 235.75 - 241.75 m Covered. - 241.75 - 247 m Sandstone, very coarse grained to coarse grained white/grey, weathers creamy/rusty blebs. Lots of cross bedding outlined by pebbles 3mm in diameter. Occassional rounded pebbles 1cm in diameter. Weathers crumbly. Sample J90-01213.  312  SECTION 29 - TASEKO RIVER, east side, about 1km north of Davidson Bridge. (920/12; UTME 451.500 UTMN 5713.200) This section was measured through the upper Cretaceous (Cenomanian) Kingsvale Group. The section is a total of 203.3m thick but is not continuous and has many covered areas. Bedding 016/19SE. Starting elevation was 1225m, beside the Taseko River. - 0 - 15 m  Massive, clast supported conglomerate. Poorly sorted, shows no grading. Clasts are mainly rounded, largest clast is 30 x 15 cm. Clasts vary from 130cm in diameter, averaging 5cm. Clasts are mainly volcanic (dark grey feldspar porphyritic, dark grey and fine grained) and intrusive (pink or black and white granite) in composition with minor amounts of sedimentary (laminated black and grey) and chert (grey or white) clasts. The matrix is coarse to medium grained white green sandstone. The whole outcrop is jointed and fractured, some appears sheared. Clasts can be removed fairly easily. Outcrop is covered in a white, limey deposit. Elevation 1235 m. Here the conglomerate seems to grade from large clasts up to slightly smaller ones. Clasts are crudely aligned. Also seen are some coarse grained, green sandy beds, these are discontinuous and vary from 20-40cm thick. The largest clast here is 50 cm in diameter. The matrix is medium grained, pebbly sandstone. Clasts still do not show any real grading or sorting (looks like lithified till). - 15 - 27 m  Conglomerate. Beds vary from matrix supported to clast supported. At the base the conglomerate is matrix supported and mainly composed of pebbly sandstone. This changes rapidly upwards to clast supported conglomerate. Individual beds are about lm thick, some have scoured bases with scours 3-15 cm deep. Bedding 016/19SE. - 27 - 36 m - 36 - 39 m - 39 - 43.5 m - 43.5 - 47.5 m - 47.5 - 51.5 m - 51.5 - 54.5 m - 54.5 - 57.5 m - 57.5 - 62.3 m  Covered. Possibly matrix supported conglomerate. Elevation 1250 m. Matrix supported conglomerate. Covered. Possibly matrix supported conglomerate. Clast supported, poorly sorted conglomerate. Covered. Clast supported, poorly sorted conglomerate. Covered.  313  Clast supported, poorly sorted conglomerate. - 62.3 - 68.3 m - 68.3 - 69.8 m - 69.8 - 76.8 m - 76.8 - 79.3 m  Covered. Matrix supported, poorly sorted pebbly sandstone and conglomerate. Covered. Clast supported, poorly sorted conglomerate.  - 79.3 - 103.3 m Covered. - 103.3 - 104.8 m Clast supported, poorly sorted conglomerate. - 104.8 - 125.8 m Covered. - 125.8 - 126.3 m Matrix supported, poorly sorted conglomerate. - 126.3 - 201.3 m Covered. - 201.3 - 204.3 m Elevation 1322m. Clast supported conglomerate. Overall less poorly sorted, maximum clast size 15cm, average 5cm in diameter, there are very few large clasts. Clasts are rounded and still mainly volcanic or granitic in composition, with minor grey and white chert. Still strongly fractured and jointed vertically, joints strike roughly north-south and cut through the pebbles.  314  SECTION 30 - CHILKO RIVER (93B/4; UTME 463.500 UTMN 5769.150) Section off a logging road under a bridge crossing the Chilko River, flat lying, interbedded Sandstone and chert pebble conglomerate, all contacts are gradational. - 0 - 0.80 m  Sandstone, medium grained, brown, well sorted, angular, micaceous, thinly bedded with individual beds 3cm thick. Composed mainly of quartz with 5% black chert. Sample J89-189-01. - 0.80 - 2 m  Chert pebble conglomerate, matrix supported, well sorted. Base of bed is small pebbles 0.5-1 cm in diameter, changes upward to include layers with larger pebbles 2-4 cm in diameter. Pebbles are sub-angular to sub-rounded and composed of 80% chert (black, pale grey, pink, red, purple), 10% quartz, 10% granitic, sedimentary and volcanic. Chert pebble conglomerate beds thin laterally from 1.20 m in the centre to 0.10m at the edges - may be channels. Sample J89-18902. - 2 - 2.28 m - 2.28 - 3.48 m - 3.48 - 6.48 m  Sandstone - same. Chert pebble conglomerate - same. Sandstone - same.  - 6.48 - 7.48 m  Pebbly Sandstone. Pebbles are angular to sub-angular, 5mm in diameter up to max of 2 cm. Pebbles occur in thin bands, 2cm wide, parallel to bedding. Sample J89-189-03. - 7.48 - 13.68 m Sandstone - 13.68 - 15.18 m Chert pebble conglomerate - 15.18 - 16.08 m Sandstone with Chert pebble conglomerate lens (50cm thick in centre, 10cm thick at ends, 2m long) - 16.08 - 17.18 m Chert pebble conglomerate - 17.18 - 19.78 m Sandstone - 19.78 - 21.03 m Chert pebble conglomerate - 21.03 - 21.48 m  315  Sandstone - 21.48 - 22.72 m Chert pebble conglomerate - 22.72 - 25.02 m Sandstone (Section is overlain by till with angular blocks (50cm square) of vesicular, grey volcanics)  316  SECTION 31 - CHURN CREEK 1 (920/7; UTME 535.250 UTMN 5703.000) Section above the road running down to Churn Creek, starting elevation 3140'. - 0 - 96 m  Interbedded Sandstone and Conglomerate (40% Sandstone, 60% Conglomerate). Sandstone, coarse grained, white to pale grey, well sorted, angular to sub-angular, cross-bedding is outlined by pebbles. Cross-bedding is planar, 15cm high X 30cm long. Sandstone is composed of black and grey chert with quartz, come feldspar and muscovite. Sandstone has thin (1mm) lams of organic matter. Also concretions from 2 - 30 cm in diameter, may be rounded or flattened to an oval Conglomerate, matrix supported, sub-angular to sub-rounded clasts aligned parallel to bedding. Clast composition - 30% black chert, 20% grey chert, 10% pink chert, jasper and red quartz, 5% white quartz, 5% clay, 10% intrusive (granitic), 20% volcanic. Conglomerate is fairly well sorted, shows graded bedding in some places. Smallest clast 5mm in diameter, largest 10cm in diameter, average 6cm. Individual Sandstone beds vary from 0.10 - 2.5m in thickness, conglomerate beds vary from 0.50 - 3m in thickness. Between Sandstone and Conglomerate beds are clay lenses within depressions in the Sandstone beds. Sandstone contains weathered out rusty areas - may have been organic matter. Minor laminations of magnetite lmm thick. Clay Samples J89-236-06,07 -96- 147 m  interbedded Sandstone and Conglomerate (70% Sandstone, 30% Conglomerate). - Sandstone and Conglomerate are same. - 147 - 244 m Interbedded Conglomerate and Sandstone, cliff forming (75% Conglomerate, 25% Sandstone). Sandstone, coarse grained, pale brown, well sorted, sub-angular to angular grains, composed of black and dark grey chert, white or colourless quartz with minor amounts of feldspar and muscovite (slightly more mica than lower in the section). Planar cross-beds outlined by pebbles. Magnetite lamination lcm thick. Conglomerate, matrix supported, Fairly well sorted, subangular to sub-rounded clasts in a very coarse grained sand matrix. Clasts vary in size from 6mm - 12 cm diameter, average 8cm. Clast composition - 25% black chert, 15% grey chert, 12% pink chert, jasper and red quartz, 5% intrusive (granitic), 30% volcanic, 5% clay, 8% white quartz. Increase in volcanic clasts compared to lower in the section - 10cm in diameter, altered pale grey, feldspar phyric and chloritic volcanics and maroon volcanics and rare flow banded volcanics. Also slight increase in the amount of jasper and white quartz. Some concretions. Conglomerate beds vary in thickness from 2 - 12 m ., Sandstone beds vary from 0.10 - 1.5 m thick. This part of the section is slightly better lithified than the lower portions, no evidence of silicification. Sandstone sample 236-8.  317  SECTION 32 - CHURN CREEK 2 (920/7, UTME 532.950 UTMN 5699.150) Section starting in Churn Creek at elevation 2715'. All contacts are gradational unless otherwise stated. - 0 - 6.7 m  Very coarse grained sandstone/conglomerate. Weathers dark grey/brown, fresh is white to light grey with rusty blebs. Clast supported with angular to subrounded clasts composed primarily of varicoloured chert (mainly pale grey), fairly well sorted. Clasts vary from 5mm to 3cm in diameter. The conglomerate matrix is well sorted very coarse grained sand composed of chert and quartz, some rusty weathering patches. Outcrops show graded bedding with pebble rich layers grading up to more sand rich layers. Repetitive cycles each 10 to 15 cm thick. Outcrop is fairly friable. - 6.7 - 8.6 m  Coarse grained sandstone. Weathers greenish grey, fresh is pale green. Composed primarily of chert, rare pebbles. Massive. - 8.6 - 10.5 m  Very coarse grained sandstone/conglomerate. Same as above. Scours into underlying sandstone. Fines upwards from pebbles 3cm in diameter at the base to smaller pebbles 1cm in diameter and finally to coarse grained sand. - 10.5 - 12.9 m  Conglomerate. Weathers dark grey/brown. Clasts supported with subangular to subrounded clasts, fairly well sorted. Clasts are composed of red, grey and black chert and vary in size from 5mm to 4cm in diameter, averaging 1 to 1.5cm. Massive, friable. - 12.9 - 15.8 m  Medium grained sandstone. Weathers dark brown, fresh is pale greenish grey. Composed primarily of chert, rare pebbles < 5mm in diameter parallel to bedding. Massive. - 15.8 - 16.6 m  Conglomerate. Same as above, sub angular to sub rounded chert clasts vary from 0.8 to 4cm in diameter. - 16.6 - 17.05 m Very coarse grained sandstone. Weathers dark grey/brown, composed of chert, massive. - 17.05 - 17.4 m Conglomerate. Same as above, Coarsens upwards from pebbles < lcm in diameter to pebbles > 2cm in diameter. - 17.4 - 18.9 m  Coarse grained sandstone. Same as above with rare pebbles < 1cm in diameter aligned parallel to cross bedding?. - 18.9 - 22.4 m  318  Coarse grained sandstone with pebbles. Weathers pale grey, friable. About 40% chert pebbles 0.8cm in diameter. At the base of the bed the pebbles are larger and average 1.2 cm in diameter with a maximum diameter of 5cm. The size of pebbles decreases towards the top of the bed but the number of pebbles increases to 50%. At the top the average pebble diameter is 5mm. Rare shale clasts 5cm long. - 22.4 - 23.15 m Conglomerate. Same as above, clasts average 1.5 cm in diameter and vary from 0.5 to 3cm in diameter. Gradational contact with lower bed. Clast composition of conglomerates includes grey, black, brown/grey, white/cream and rare red chert; black fine grained volcanics, rare creamy volcanics with pale brown clasts, rare dark purple volcanics and rare feldspar phyric fine grained pale green volcanics; rare intrusive clasts with pink kspar and large quartz or pink with hornblende and feldspar; and white quartz. - 23.15 - 23.5 m Very coarse grained sandstone with 20% pebbles. Weathers rusty brown/grey, massive. Pebbles are chert with rare pink and white coarse grained intrusive clasts. - 23.5 - 24.5 m  Very coarse grained sandstone with 30% pebbles - pebbles are now concentrated parallel to bedding. Weathers rusty brown. At base of bed are larger pebbles up to 5cm in diameter for 10cm. Within this bed alternating layers of pebble rich and less pebble rich sandstone occur each 30cm thick. - 24.5 - 30 m  Very coarse grained to coarse grained sandstone with 2% pebbles. Weathers grey/brown to rusty brown, fresh is pale green. Overall this bed fines upwards and has individual fining upward cycles 10cm thick. - 30 - 34.7 m  Coarse grained sandstone with pebbles. Same as above. Pebble rich layers are 30 to 50 cm thick and sandy layers are 40 to 60 cm thick with individual beds 2cm thick. Pebbles vary from 1 to 5 cm in diameter. - 34.7 - 35.4 m  Changes abruptly to medium grained, micaceous, organic matter rich sandstone. Weathers dark green/black, flaggy. Has rounded mud chips up to 1.5 cm in diameter, organic rich laminations lmm thick spaced 3mm apart. Rare pebbles. Sandstone is discontinuous and lensoid. - 35.4 - 36.4 m  Changes abruptly to coarse grained sandstone. Weathered and fresh surfaces are yellowish brown. Rare pebbles up to 2cm in diameter. Massive. - 36.4 - 37.4 m  Coarse grained sandstone with 60% pebbles. Pebble rich layers 40 to 50 cm thick are separated by sandy layers 10 to 15 cm thick. Pebbles vary from 0.6 to 4cm in diameter and aligned parallel to bedding. - 37.4 - 38.8 m  Changes abruptly to fine grained, micaceous organic rich sandstone. Weathers dark brown, fresh is dark green/black, flaggy and highly fractured.  319  - 38.8 - 40.6 m  Covered. Mainly float of white siliceous volcanic with quartz phenocrysts and tiny acicular hornblends and biotite. - 40.6 - 41.15 m Medium grained sandstone with 30% pebbles. Sub rounded to rounded pebbles 5cm in diameter. - 41.15 - 43.95 m Covered. - 43.95 - 45.1 m Coarse grained sandstone. Weathers pale green/grey, fresh is pale green. Rare pebbles 1cm in diameter. Friable, massive. - 45.1 - 47 m  Interbedded coarse grained sandstone and pebbly layers. Outcrop weathers brownish green, some pebbles are rusty. Pebbly layers have 50% subangular to subrounded pebbles from 1 to 5cm in diameter. Towards the top of the outcrop pebbly layers fine upwards to smaller pebbles 0.8cm in diameter. Pebbles are aligned parallel to bedding. Sandstone layers are weakly laminated with laminations spaced 1cm apart. Pebbly layers are 20 - 50 cm thick, sandy layers are 20 - 30 cm thick. - 47 - 49.8 m  Very coarse grained sandstone. Weathered and fresh surfaces are pale grey. Massive, composed of chert. - 49.8 - 52.6 m  Coarse grained sandstone with 50% pebbles. Weathers brown green/grey, fresh is pale green/grey. Pebble layers define cross-bedding. Sub angular to sub rounded pebbles vary from 0.5 - 1.5 cm in diameter. Sandy layers are 20cm thick and have undulatory contacts with the pebbly layers. Outcrop is very friable and flaggy, weathers into thin layers 2 - 5 cm thick.  320  SECTION 33 - CHURN CREEK 3 (NTS 920/7; UTME 532.560 UTMN 5699.420) Section starting at 2940', above Churn Creek section 1. All contacts are gradational unless otherwise stated. - 0 - 0.85 m  Coarse grained sandstone with 3% pebbles. Weathers grey/green to dark brown, fresh is pale green. Composed of chert with lesser quartz and minor mica. Chert and quartz pebbles average 6mm in diameter. Coarser pebbles up to 2cm in diameter occur at the base of the bed for a thickness of 15cm. In the centre of the bed pebbles are aligned parallel to bedding. Overall the bed is crudely laminated with lams 15cm apart. - 0.85 - 2.45 m  Coarse grained sandstone with 30% pebbles. Weathers pale grey/green to rust, fresh is pale green. Fines upward from pebbles 3cm in diameter at the base to pebbles 0.3 to 0.5 cm in diameter at the top. The bottom 30cm of this bed has > 30% pebbles. Pebbles are aligned parallel to bedding. Overall the outcrop is planar bedded with beds 5cm apart. - 2.45 - 3.45 m  Conglomerate channel through finer grained sandstone. On the down dip side of this outcrop are medium grained, planar laminated (spaced 1.5cm apart) sandstone beds 30cm thick. These beds grade into small pebbles with a maximum d