STRATIGRAPHY OF THE HARPER RANCH GROUP AND TECTONIC HISTORY OF THE QUESNEL TERRANE IN THE AREA OF KAMLOOPS, BRITISH COLUMBIA
by Tyler Wayne Beatty B.Sc., University of Western Ontario, 1997
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
In the Department of Earth Sciences
43 Tyler Beatty 2003 SIMON FRASER UNIVERSITY November 2003
All rights reserved. This work may be reproduced in whole or in part with permission of the author APPROVAL
Name: Tyler Beatty
Degree: Master of Science
Title of Thesis: Stratigraphy of the Harper Ranch Group and Tectonic History of the Quesnel Terrane in the Area of Kamloops, British Columbia
Examining Committee:
Chair: Dr. Diana Allen Associate Professor
dr. peter Mustard Senior Supervisor Associate Professor
mes MacEachern rvisory Committee Member iate Professor
D'r. ~=el Orchard .--- Supervisory Committee Member Geological Survey of Canada
Dr. kmes Wn'ger External Examiner Adjunct Professor SFU Earth Sciences
Date Approved: November 28, 2003 PARTIAL COPYRIGHT LICENCE
I hereby grant to Simon Fraser University the right to lend my thesis, project or extended essay (the title of which is shown below) to users of the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its own behalf or for one of its users. I further agree that permission for multiple copying of this work for scholarly purposes may be granted by me or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without my written permission.
Title of ThesislProjectlExtended Essay:
Stratigraphy of the Harper Ranch Group and Tectonic History of the Quesnel Terrane in the Area of Kamloops, British Columbia
Author: (signadre) -
Tyler Wayne Beatty (Name)
-- -(Date) ABSTRACT
The late Paleozoic Harper Ranch Group (Harper Ranch Group) of south-central British
Columbia is a >3 km thick sedimentary succession consisting mostly of marine siliciclastics and carbonates. In the area of Kamloops, the Harper Ranch Group comprises the oldest rocks of Quesnel Terrane. Here, the Quesnel Terrane comprises three unconformity bound successions of island-arc affinity: the Harper Ranch Group, the Late Triassic Nicola Group, and the Early Jurassic Rossland Group. Each succession records subduction-related volcanism and associated sedimentation. Three new formation-rank stratigraphic units are recognized in the Harper Ranch Group. The clastic Tk'emlups Formation, overlain successively by the predominantly carbonate
South Thompson and McGregor Creek formations are all formally defined with type sections and detailed descriptions. The South Thompson Formation records volcanic quiescence, the end of volcano-sedimentary sedimentation of the Tk'emlups Formation, and development of arc flanking carbonates in the Late Mississippian. Pre-Early
Permian uplift and erosion of Harper Ranch Group units are implied by the character and lithology of the Permian McGregor Creek Formation, a secondary chert-rich carbonate platform succession. Upper Permian to Middle Triassic rocks are not recognized in the area. The Nicola Group records renewed arc-related volcanism, sedimentation, and plutonism in the Late Triassic. The Rossland Group, represented by conglomerate, agglomerate and undifferentiated volcanics, represents a third, Early Jurassic, island-arc succession. Rocks of the Rossland Group unconformably overlie those of the McGregor
Creek Formation. New biostratigraphic data from each of the Harper Ranch, Nicola, and
Rossland groups, in concert with map relationships, provide time constraints for the tectonic evolution of Quesnel Terrane.
iii For my parents and grandparents. Their support was integral to this achievment. ACKNOWLEDGEMENTS
Foremost, I acknowledge the financial and logistical support of the Geological
Survey of Canada (GSC), the National Sciences and Engineering Research Council
(NSERC Grant to P. Mustard), and Simon Fraser University.
I am indebted to my supervisor, Peter Mustard, for providing an environment in which I could complete this project. I thank Michael Orchard for encouraging me to return to academics and for introducing me to the wonderful world of microproblematica.
Field research for this project was implemented as part of the Ancient Pacific Margin
National Geoscience Mapping Program (NATMAP) project of the GSC. I must thank
Bob Thompson for providing this umbrella under which this project could survive.
Ted Danner, Wayne Bamber, and Lin Rui are thanked for their expert paleontological skills and moreover their excellent conversation. Charles Henderson helped me hone my skills as a geologist and paleontologist. James MacEachern and J-
P Zonneveld taught me the value of sedimentology and ichnology; J-P also taught me to appreciate an Islay.
John Jules of the Kamloops Indian Band is thanked for providing access to the bands ancestral land. John Wong of the Canada Lafarge Cement Company was helpful in providing access to the quarry and surrounding land. I especially would like to thank
Natalka Allan, Spencer Beatty, and Stephen Haas for their expert field assistance.
Finally I would like to thank the grad-crew (and associates), they provided me with friendship, entertainment, understanding, adventure (Slopers), and respect that, if expounded, could fill volumes.
Rebecca preceded and endured this oeuvre; I am forever beholden. TABLE OF CONTENTS
Approval ...... ii ... Abstract ...... IH
Dedication ...... iv
Acknowledgements ...... v
Table of Contents ...... vi ... List of Figures ...... VIII
List of Tables ...... x
CHAPTER 1: INTRODUCTION ...... I Objectives of the Study ...... 1
Methods of Study ...... 2
Thesis Format ...... 3 Location ...... 3 General Geology and Previous Work ...... 5
CHAPTER 2: GEOLOGY AND FORMAL DEFINITION OF THE HARPER RANCH GROUP. KAMLOOPS. BRITISH COLUMBIA ...... 9 Abstract ...... 9
Introduction ...... I0 Geologic Setting ...... II
Lithostratigraphy...... -14 Harper Ranch Group ...... 14 Type area and composite type section ...... 17 Definition ...... 17 Tk'emlups Formation ...... 19 Type section and reference section ...... 21 Definition ...... -24 Fauna ...... 28 South Thompson Formation ...... 29 Composite Type Section ...... 32 Definition ...... 34 Fauna ...... 44 McGregor Creek Formation ...... 46 Type Locality and Section ...... 48 Definition ...... 51 Fauna ...... 52 Depositional History ...... 53
CHAPTER 3: TECTONIC HISTORY OF THE QUESNEL TERRANE IN THE AREA OF KAMLOOPS. BRITISH COLUMBIA ...... 57
Abstract ...... $57
Introduction ...... 58 Regional Geologic Setting ...... 59
Stratigraphy...... 64
Harper Ranch Group ...... 64 Tk'emlups Formation ...... 66 South Thompson Formation ...... 72 McGregor Creek Formation ...... 76 Nicola Group ...... 78 Dome Hills Succession (Unit uTrNs) ...... 81 Armour Creek Succession (uTrNvs) ...... 83 Rayleigh Conglomerate (uTrNc) ...... 85 Lions Head Volcanics of the Rossland Group ...... 90 Intrusive Rocks...... 93 Heffley Creek Pluton ...... 94
Paul Peak Stock ...... 94
Mount Fleet Alkali Complex ...... 95
Tectonic History ...... 96
Conclusions...... 440
REFERENCES ...... 112
APPENDIX A- Measured stratigraphic sections ...... 121
APPENDIX B- Fusulinacean Identification ...... 134
APPENDIX C- Coral Identification ...... 151
APPENDIX D- Conodont Processing and lndentification ...... 152
vii LIST OF FIGURES
Figure 1. (a) Location of study area in western Canada. (b) Hillshade relief map encompassing the study area northeast of Kamloops, B.C...... 4
Figure 2. (a) Simplified geologic map of the Kamloops area (b) Legend for Figure 2a. .I3
Figure 3. (a) Composite stratigraphic succession in the area of Kamloops, B.C. (b) General stratigraphic column of the Harper Ranch Group and its component formations in the area of Kamloops, B.C. (c) General location of measured sections used to construct the composite section of 3b...... 18
Figure 4. Location map for type and reference sections of the Tk'emlups Formation (Fig. 5) and South Thompson Formation (Fig. 7); see Fig. 2a for regional location...... 22
Figure 5. (a) Tk'emlups Formation type section (b) Tk'emlups Formation reference section ...... 23
Figure 6. Thin-section photomicrographs of sandstone and interbedded mudstone and siltstone of the Tk'emlups Formation...... 26
Figure 7. South Thompson Formation composite section ...... 35
Figure 8. Thin-section photomicrographs of representative limestone microfocies of the South Thompson Formation ...... 37
Figure 9. (a) McGregor Creek Formation type section (section MCI) (b) Location map for type section of the McGregor Creek Formation...... 49
Figure 10. Block diagrams schematically depicting deposition of Harper Ranch Group interpreted from type sections ...... 54
Figure 11. (a) Location of study area in western Canada. (b) Hillshade relief map encompassing the study area northeast of Kamloops, B.C...... 60
Figure 12. (a) Simplified geologic map of the Kamloops area (b) Legend for 12a ...... 62
Figure 13. (a) Composite stratigraphic succession in the area of Kamloops, B.C. ... Vlll (b) General stratigraphic column of the Harper Ranch Group and its component formations in the area of Kamloops. B.C. (c) General location of measured sections ...65
Figure 14. Thin section photomicrograph and outcrop photos of select lithologies of the Harper Ranch and Rossland Groups ...... 68
Figure 15. Schematic cross-section showing relationship of Nicola Group strata to that of the Harper Ranch Group ...... 80
Figure 16 . Time stratigraphic columns for the Chilliwack. Quesnel. Slide Mountain. and eastern Klamath terranes ...... 98
Figure A.1 . Legend for measured sections of Appendix A ...... 122
Figure A.2a . TKI Section. type section of the Tk'emlups Formation ...... 123
Figure A.2b . TKI Section. type section of the Tk'emlups Formation ...... 124
Figure A.2c . TKI Section. type section of the Tk'emlups Formation ...... 125
Figure A.3a . TK2 Section. type section of the Tk'emlups Formation ...... 126
Figure A.3b . TK2 Section. type section of the Tk'emlups Formation ...... 127
Figure A.3c . TK2 Section. type section of the Tk'emlups Formation ...... 128
Figure A.3d . TK2 Section. type section of the Tk'emlups Formation ...... 129
Figure A.4a . ST1 Section. reference section of the South Thompson Formation ...... 130
Figure A.4b . ST1 Section. reference section of the South Thompson Formation ...... 131
Figure A.5a . ST2 Section. type section of the South Thompson Formation ...... 132
Figure A.6a . MC1 Section. type section of the McGregor Creek Formation ...... 133
Figure BP.1 . Geology Map of the Harper Ranch Group and bounding geologic units in the Kamloops area. B.C...... back-pocket LIST OF TABLES
Table 1. Details of key fossil collections used to constrain distribution of units in Figure 16...... 97
Table A.1 . Measured section locations in UTM coordinates ...... 121
Table B.1 . Fusulinacean samples and identification ...... 134
Table C.1 . Coral samples and identification ...... 151
Table D.1 . Conodont sample processing records and identification ...... 152 CHAPTER 1: INTRODUCTION
Objectives of the Study
The objectives of this research are: 1) to document the succession of upper Paleozoic and lower Mesozoic strata in the Kamloops area; 2) to formalize the stratigraphy of the Harper Ranch Group and its component formations; and
3) to synthesize these data in a model of the environmental and tectonic evolution of this succession. Strata cropping out in the Kamloops area provide a
record of island-arc related sedimentation during the pre-accretionary history of the Quesnel Terrane. Documentation of a type-area stratigraphy will facilitate regional correlation with Paleozoic and Mesozoic strata elsewhere in the Quesnel
Terrane, as well as adjacent and related terranes in the Cordillera. Regional and extra-regional correlations are aided by an up to date fossil record (Appendices
B, C, D); fossil data are also used to constrain the timing of pre-Jurassic tectonic events.
Geologic mapping at 1:50,000 scale forms the basis of this study, outlining the distribution of formations, members, and lithologic units of the Harper Ranch
Group and overlying strata in the Kamloops area (Fig. BP-1, backpocket). The fossil content and the nature of contacts between rock units are emphasized as they provide evidence for the environmental and tectonic evolution of these strata respectively. Methods of Study
This study was initiated as part of the Ancient Pacific Margin NATMAP, a regional mapping program of the Geological Survey of Canada (G.S.C.) with Dr.
R.I. Thompson of the Cordilleran Division, G.S.C., as coordinator and principal researcher. Mapping at 1:250,000 scale (Monger and McMillan, 1984) provided the initial geological base for this study. All rocks in the study area were remapped at 1:20,000 scale and are presented at 1:50,000 scale (back pocket
Fig. BP-1). Mapping was undertaken during two one month field seasons
(summers of 2000 and 2001), plus two weeks in 2002. In addition to geologic mapping, five stratigraphic sections were measured through Harper Ranch
Group sedimentary rocks. The resultant stratigraphic logs with section descriptions are presented in Appendix A. Field observations were supplemented by the examination of 33 thin sections and 9 polished slabs. A further 93 thin sections were prepared from carbonate rocks for the purpose of fusulinacean fossil identification and age determination by Dr. L. Rui, G.S.C.
(Calgary) and the results are given in Appendix 6. Eight samples of carbonate rocks were sent to Dr. W. Bamber, G.S.C. (Calgary) for coral macrofossil identification and age determination, (Appendix C). One hundred and fifteen samples of carbonate rocks were collected for conodonts. Processing methods and records, as well as a list of taxa recovered, their ages, and Color Alteration
Index (CAI) determinations are presented in Appendix D. Thesis Format
This thesis consists of: introductory material; two self-contained, journal- style chapters; appendices of data and analytical methods; a combined reference list; and a 1:50,000 scale geological map presented as a back pocket figure (Fig.
BP-1). To limit repetition of text and figures inherent in this style of thesis, sections detailing location, general geology, and previous work are presented in detail only in the introduction (Chapter 1) allowing for more topically directed subjects of these to be included in subsequent chapters. Figures are numbered consecutively beginning with Chapter 1. To further reduce repetition the references and acknowledgements are combined rather than being presented for each chapter. The format of individual chapters follows that which is recommended by the journal to which the chapter will be submitted (Chapter 2 =
Canadian Journal of Earth Sciences, Chapter 3 = Geological Association of
Canada Special Publication).
Location
The area totals approximately 726 square kilometres and is situated in the southern Canadian Cordillera east and northeast of the city of Kamloops, British
Columbia (Fig. I)encompassing B.C. provincial TRIM map sheets 9211.069,
9211.070, 9211.079, 9211.080, 9211.089, 82L.061, 82L.071, and 82L.081. It is bounded to the south by the South Thompson River, to the north by Heffley Lake
Road, to the northeast by Louis Creek, and to the west by the North Thompson
River (Fig. IB). Fig. 1. (A) Location of study area in western Canada with reference to The
Quesnel Terrane and the five morphogeologic belts of the Cordillera (modified from Wheeler and McFeely, 1991). (B) Hillshade relief map encompassing the study area northeast of Kamioops, B.C.
This area is part of the southern Interior Plateau of the Canadian
Cordillera, the South Thompson Upland, a Tertiary erosion surface significantly modified by Pleistocene glaciations (Fulton, 1975). The geomorphology is characterized by a series of large broad upland blocks separated major valleys enhanced during late Pleistocene glacial erosion. The study area encompasses several different climatic environments, ranging from desert-like south facing slopes, to heavily forested regions near Paul and Heffley lakes, as well as larger
north-facing slopes such as Mt. Fleet (Fig.1 B). Much of the area is covered with glacial and post-glacial sediment and is vegetated, except where limestone crops out along prominent hills, or siliciclastics and volcaniclastics are exposed along gullies and streams. This physiography is characteristic of much of the
Intermontane Belt (Fulton, 1975).
An extensive network of logging roads facilitates access and active logging continues throughout the northern half of the study area. Much of the area is within the territorial boundaries of the Kamloops Indian Band and permission to access these portions was granted. Permission was also granted from the Canada Lafarge Corporation to access the important exposures of
Permian strata that outcrop as part of a major limestone quarry and form prominent limestone exposures in the hills above the quarry.
General Geology and Previous Work
The Harper Ranch Group, part of the basal strata of the Quesnel Terrane
(Fig. IA), comprises limestone, siliciclastic, and volcaniclastic rocks of island-arc origin (Smith, 1979; Monger and McMillan, 1984). The type area of the Harper Ranch Group crops out east and northeast of the city of Kamloops. The Quesnel
Terrane, the eastern-most of the tectonostratigraphic terranes in the
lntermontane Belt (Fig. IA), is made up of two upper Paleozoic sub-terranes, the
Harper Ranch and the Okanagan, overlapped by the Upper Triassic Nicola
Group. The Nicola Group and its regional correlatives, the Slocan and Takla formations, represent magmatic-arc and associated sedimentary successions
related to Late Triassic subduction (Mortimer, 1987). The Quesnel Terrane and the other component terranes of the lntermontane Superterrane were accreted to
rocks of the former continental margin as tectonic flakes during the Middle
Jurassic (Price and Monger, 2000).
The strata in the Kamloops region were first studied by G.M. Dawson in
1879 and included by him within the Cache Creek Complex, which is located
approximately 100 km to the west of Kamloops (Danner & Orchard, 2000).
Subsequent studies by Daly (191 5) and Cockfield (1948) provided more detailed
lithologic descriptions, but maintained this correlation. The term "Harper Ranch
Group" was first used by Smith (1979) in his master's thesis, in reference to
upper Paleozoic rocks in the Kamloops region previously referred to as the
"Harper Ranch beds" (Sada and Danner, 1974; 1976), so called for their
proximity to the Harper family ranch house (Fig. 1B).
Until the mid-19801s, research on the Harper Ranch Group concentrated
on the occurrence of fusulinaceans (Thompson & Verville, 1950; Skinner &
Wilde, 1966; Sada & Danner, 1974, 1976), ammonoids (Miller & Warren, 1933),
rugosan and tabulate corals (Nelson, 1982; Nelson & Nelson, 1985), and brachiopods (Nelson & Nelson, 1985). Subsequently, the presence of Upper
Devonian (Upper Famennian), Upper Mississippian (Upper Visean to
Serpukhovian) (Orchard, 1984; Orchard, 1987; Orchard, 1991; Danner et a/.,
1999; and Danner and Orchard, 2000), and Lower to Middle Permian strata
(Orchard & Forster, 1988; Danner et a/., 1999; and Danner and Orchard, 2000)
was demonstrated by conodont studies carried out by M.J. Orchard (G.S.C.,
Vancouver).
Except for a regional study of the Ashcroft map area (NTS map sheet 92 1;
Monger & McMillan, 1984), attempts at placing the Harper Ranch Group into a
regional geological context have been limited, leaving much unknown about the
internal and external relationships of this important part of the Quesnel Terrane.
In the type area, the Harper Ranch Group is truncated to the west by
steep normal faults and juxtaposed with Triassic, Nicola Group volcaniclastics
(Smith, 1979; Monger and McMillan, 1984). To the east it is in fault contact with,
and unconformably overlain by, Triassic and Jurassic sedimentary rocks (Beatty,
2002; Figure BP-1). Outcrop distributions appear random, except that,
carbonates tend to occur as parts of hilltops and siliciclastics are commonly within valleys and along ridges, likely reflecting unit competency rather than original distribution. Plutons of Late Triassic to Early Jurassic age (Ray and
Webster, 2000) intrude the Harper Ranch Group in the northern study area south of Heffley Lake, in the region of Mt. Fleet, and in the southwestern part of the study area on Paul Peak. Lamprophyric dykes of post-Permian age are scattered throughout the area (Smith, 1979). Regional metamorphism has altered all pre-Jurassic age strata to prehnite
- pumpellyite grade. Conodonts collected from Devonian- to Triassic-age strata
display Colour Alteration Index (CAI) values between 5 and 6, inferring absolute
heating of the enclosing strata to 300-400 OC and possible burial to >8000 m
(Nowlan and Barnes, 1987).
Faulting is common in both the Harper Ranch and Nicola groups. Isoclinal
folding is apparent in much of the Nicola Group and is best exposed in the Dome
Hills region in a roadcut along highway 5 north of the town of Rayleigh (Fig. BP-
I)and further, north of the village of Heffley Creek. Close folding was observed
only in Permian strata of the Harper Ranch Group. Map relationships and
unconformable contacts suggest these strata have been involved in multiple episodes of deformation. CHAPTER 2: GEOLOGY AND DEFINITION OF THE HARPER RANCH GROUP, KAMLOOPS, BRITISH COLUMBIA'
Abstract
The upper Paleozoic Harper Ranch Group of south-central British
Columbia is a >3 km thick sedimentary succession made up of marine volcaniclastics, siliciclastics, and carbonates. The Harper Ranch Group consists
of the Upper Devonian to Mississippian Tk'emlups Formation, the Upper
Mississippian South Thompson Formation, and the Permian McGregor Creek
Formation. Formal definitions with type sections are given for each formation.
The Tk'emlups Formation comprises at least 2600 m of mudstone, chert,
siltstone, and fine- to very coarse-grained volcaniclastic sandstone, tuffaceous
breccia, and conglomerate. This unit consists of a thick succession of
hemipelagic mudstone and distal turbidites, interstratified with and overlain by, a variety of volcaniclastic sediment-gravity flow deposits. These deposits include
both epiclastic-rich and pyroclastic-rich (tuffaceous) mass flows, the latter
increasing in thickness and abundance up-section. The ca. 300 m thick South
Thompson Formation interfingers with, and overlies, the Tk'emlups Formation. It
consists of skeletal grainstone, packstone, and wackestone with minor lime-
mudstone and conglomerate beds. A conglomeratic unit locally occurs between the South Thompson and McGregor Creek formations and a massive volcaniclastic unit occurs within the South Thompson Formation. These units are
1 This chapter is formatted using the style guidelines of the Canadian Journal of Earth Sciences. 9 defined as the Conglomerate and Sandstone members of the South Thompson
Formation respectively. The McGregor Creek Formation unconformably overlies both the Tk'emlups and South Thompson formations and comprises at least 500 m of packstone, wackestone, and grainstone, in a generally fining-upward succession. The McGregor Creek Formation was deposited as part of a carbonate platform. Volcanosedimentary rocks of the Mesozoic Nicola and
Rossland groups, as well as basalt of the Cenozoic Kamloops Group unconformably overlie the Harper Ranch Group in the area. The Tk'emlups and
South Thompson formations display sedimentary and lithological characteristics that indicate various settings within an island-arc environment.
Introduction
The uppermost Devonian to Permian Harper Ranch Group of southern
British Columbia consists of a thick succession of volcanosedimentary rocks and limestone that, in the Kamloops area, represent the oldest strata of the Quesnel
Terrane (sometimes called Quesnellia; Danner and Orchard, 2000). Although the name "Harper Ranch Group" has been in common use since 1979 (Smith,
1979), its formal lithostratigraphic standing has never been established. This article provides the first formal lithostratigraphic definition of the upper Paleozoic
Harper Ranch Group, including a composite stratotype. Also documented is division of the Harper Ranch Group into three discrete formations, one of which contains member rank subdivisions.
The purpose of formally recognizing the Harper Ranch Group and its subdivisions is to facilitate correlations with units previously correlated solely on homotaxial relationships. Further, recognition of the internal divisions of these units, some of which are bounded by significant unconformities, will aid in the development and testing of tectonic models concerning both the inception and the amalgamation of the Quesnel Terrane. Evaluation of such models, however, is beyond the scope of this paper.
Geologic Setting
The Harper Ranch Group comprises carbonate, siliciclastic, and volcaniclastic rocks thought to be of island-arc origin, forming a part of the stratigraphic base of the Quesnel Terrane (Smith, 1979; Monger and McMillan,
1984). The Quesnel Terrane, eastern-most of the tectonostratigraphic terranes in the Intermontane Belt of the Canadian Cordillera (Fig. IA), is made up of two upper Paleozoic sub-terranes, the Harper Ranch and the Okanagan, overlain by the Upper Triassic Nicola Group, and locally, the Lower Jurassic Rossland
Group. The Nicola Group and its regional correlatives, the Slocan and Takla formations, have been interpreted as an overlap assemblage related to the Late
Triassic amalgamation of the older parts of the Quesnel Terrane (Nelson et a/.,
1995). The Quesnel, Cache Creek and Stikine terranes were accreted onto rocks of the former North American continental margin as tectonic flakes during the
Jurassic (Price and Monger, 2000).
In the Kamloops region, the Nicola Group comprises volcanic rocks of island-arc affinity and their associated sedimentary strata. Mapping during the course of this study identified two stratigraphic successions: the Dome Hills and
Armour Creek (Fig. 2, BP-I), comprising mudstone, siltstone, and volcaniclastic sandstone of Late Triassic (Carnian to early Norian) age. A third conglomeratic succession unconformably overlies Permian limestones of the McGregor Creek
Formation in both the eastern and western parts of the study area. The Nicola
Group is intruded by two mafic-ultramafic, Alaskan-type plutons: the Heffley Lake
Pluton and the Paul Peak stock (Fig. 2;Smith, 1979; Ray and Webster, 2000).
The former has yielded an UIPb date of 208+/- 6.1 Ma from zircons (Friedman et a/.,2002).
Rocks correlated with the Rossland Group have recently been identified in the area (Beatty, 2002). These strata overlie, with angular unconformity,
limestones of the Harper Ranch Group in the areas north and east of the Lafarge
Quarry (Fig. 2). This succession of mainly volcanic cobble conglomerate,
agglomerate, and volcanic rocks is called the Lions Head volcanics (informal).
Fossils from the base of the succession are of Early Jurassic (Sinemurian) age
(Beatty, 2002). Relationships between the Nicola and Rossland groups are
poorly understood in the area due to the large areas of Tertiary basalt that conceal contacts (Fig. 2). Vesicular and amygdoidal basalt, and locally, fluvial and lacustrine lithic sandstone, of Eocene to Miocene (?) age cover a large area
in the southeast part of the study area (Fig. 2, Fig. BP-1). These rocks are assigned to the Kamloops Group. Figure 2. (a) Simplified geologic map of the Kamloops area, boxed areas outline sections as in Figs. 3c14, 6, 7, and 9. DHF = Dome Hills Fault; HLF = Heffley Lake Fault; LCF = Louis Creek Fault; RCF = Robbins Creek Fault; TRF =
Thompson River Fault. Contour interval is 200 m. (b) Legend for Figure. 2a.
El ~ockUnit
Quaternary
Quaternaw: glacio-fluvial / lacustrine silt; ddff fault: unknown displacement KAMLOOPS GROUP Eocene (Miocene?) "1300 - -.,, Contour line, elevation in metres, basalt, minor sandstone, siltstone contour interval 200 m
INTRUSIVE ROCKS Late Triassic - Early Jurassic Mount Fleet Alkaline Complex: mega-cryst syenite, quartz monzonite MafidUltramafic intrusives-granodiorite, diorite, clinopyrixenite, quartz monzonite, includes Heftley Creek Pluton and Paul Peak stock ROSSLAND GROUP Lower Jurassic Lions Head Volcanic member: andesite, volcanic breccia, conglomerate, siltstone, agglomerate NICOLA GROUP Upper Triassic ---- Rayleigh conglomerate - kg limestone and volcanic lithic conglomerate, minor siltstone, sandstone, pelite Armour Creek Succession- andesite, basaltic andesite, tuff, slltstone, minor pillow basalt Dome Hills Succession- argillite, siltstone, sandstone, andesite, chert, limestone, augite porphyry, tuft pillow basalt HARPER RANCH GROUP Permian McGregor Creek Formation: limestone Upper- Mississippian T South Thompson Formation: limestone, Ih-qminor volcaniclastic sandstone, conglomerate Upper Devonian - Mississippian Tk'emlups Formation: mudstone, siltstone, volcaniclastic sandstone, tuff, conglomerate, chert,
Distribution of Harper Ranch Group units in outcrop appears random.
However, carbonates tend to occupy hilltops and siliciclastics are more common within valleys and along ridges. This distribution likely reflects differential erosion rather than original disposition. Attitudes of Harper Ranch Group strata are steep and generally northeast dipping in the less deformed, southern part of the study area (Fig. BP-1) but in the northern part are more variable or overprinted by the development of cleavage. Most faults and cleavage display a northwest- southeast trend broadly parallel to depositional strike.
Regional metamorphism (Fig. BP-1) has altered all pre-Eocene strata to sub-greenschist grade (Smith, 1979). Conodonts recovered from Devonian- to
Triassic-age strata display Colour Alteration Index (CAI) values between 5 and 6, inferring absolute heating to about 400" C and potential burial to >8000 m
(Nowlan and Barnes, 1987). Folding and faulting are common throughout the
Harper Ranch and Nicola groups, and map relationships suggest that these strata have been involved in multiple episodes of deformation.
Lithostratigraphy
Harper Ranch Group
In 1876, G.M. Dawson (1879) reported on rocks cropping out in the vicinity of the town of Kamloops. He assigned the succession of mainly clastic rocks and limestone to the "Cache Creek Group", then thought to be of Carboniferous age
(Dawson, 1896). Due to the relative paucity of limestone in the Kamloops area,
Dawson believed these rocks corresponded to the lower Cache Creek Complex and represented the eastern limb of a broad syncline (op. cit. p. 420) further
14 qualifying the succession as a potential itlittoral" equivalent to the Cache Creek
Complex. Dawson estimated a thickness of over 7500 feet (2300 m) of Cache
Creek Complex equivalent strata in the area of the confluence of the North
Thompson and South Thompson rivers. His measurements however, must have included at least 2000 feet (600 m) of Nicola Group strata, because he notes the presence of a conglomerate developed above a limestone at the base of his measured section. This conglomerate is now known to be part of the Nicola
Group in the area (Beatty, 2002).
Daly (1915), during reconnaissance along the Canadian Pacific Railway, measured 13,700 feet (4200 m) of strata, which he attributed to the
Carboniferous Cache Creek Complex. However, it is apparent that his measurements, which started on the western slope of Peter Peak Ridge, included over 4000 feet (1200 m) of Nicola Group strata, as well as crossing at least one fault that repeats the succession. Fossils collected from what is now known to be Permian limestone were identified as upper Pennsylvanian
("Gschelian"), while a brachiopod collected from probable Mississippian rock was interpreted as Permian (Artinskian) (Daly, 1915, p. 122). Daly presented measurements of 300 feet (90 m) and 5000 feet (1500 m) respectively for the basal conglomerate and the largely volcanic succession unconformably overlying the limestone east of what is now the Lafarge Quarry (Fig. 2). Dawson (1894) had previously assigned this succession to the Nicola Group. Though new fossil data indicate it is actually correlative with the Lower Jurassic Rossland Group
(Beatty, 2002). Additional Permian ages were determined by Miller and Warren (1933), and Miller and Crockford (1936) from studies of cephalopods collected from limestones near what is now the Lafarge Quarry (Fig. 2). Cockfield (1948) summarized the paleontological data from the area, and on the basis of the occurrence of Mississippian fauna in the Kamloops area, questioned the inclusion of these strata in the Cache Creek Complex, which in its type area had been shown to be no older than Pennsylvanian (ibid). One of the fossil localities listed by Cockfield is described as: "Harper's ranch (east of Mount Harper)", apparently the first published use of the term Harper Ranch in a geological context.
Smith (1979), following Monger's (1975) suggestion to restrict the term "Cache Creek Group" to rocks of oceanic aspect, proposed the use of Harper
Ranch Group for the upper Paleozoic rocks exposed along the South Thompson
River in the Kamloops region. The group name was derived from the use of
"Harper Ranch beds" by Sada and Danner (1974, 1976). Smith (1979) divided the Harper Ranch Group into two sections, a lower section of "more than 5,000 m" of strata of Carboniferous age, disconformably overlain by an upper section comprising Permian limestone "probably several hundred metres thick".
Additionally, Smith (1979) extended the use of Harper Ranch Group to include
"rocks of similar age and lithology in the Nicola and Vernon map-areas which were mapped by previous workers as Cache Creek Group'' (Smith, 1979).
Subsequent use of the term Harper Ranch Group has followed that of Smith (1979). We here propose that the name Harper Ranch Group is formally adopted for the upper Paleozoic strata that crop out in the Kamloops area, broadly adhering to the usage presented by Smith (1979). Type area and composite type section
The most continuous and easily accessible exposures of the Harper Ranch Group are above the Quaternary silt terraces along the north side of the South Thompson River, approximately 12 km east of the city of Kamloops (Fig. 2). Previous studies of the Harper Ranch Group have concentrated on this area (Dawson, 1879; Daly, 1915; Cockfield, 1948; Smith, 1979); accordingly, it is regarded as the type area. Due to the thickness of the unit and the structural complexity of the area, a continuous section through the entire Harper Ranch Group could not be measured, thus a composite type section is presented (Fig. 3). The type and reference sections of the formation rank subdivisions of the Harper Ranch Group also occur within this outcrop belt (Fig. 2).
Definition
The Harper Ranch Group is a series of predominantly volcaniclastic, siliciclastic (mudstone and chert), and carbonate strata of late Paleozoic age. In its type area, northeast of Kamloops, BC, the Harper Ranch Group is unconformably overlain by strata correlated with the Nicola, Rossland, and Kamloops groups (Fig. 3a). The basal beds of the Harper Ranch Group are of latest Devonian age and are overlain by a thick (>2600 m), continuous succession of interstratified volcaniclastic and siliciclastic rocks of Mississippian age (Fig. 3b). The basal beds along with this clastic succession are assigned to the Tk'emlups Formation. Conformably overlying the clastic succession is a Late Mississippian succession of mostly bioclastic limestone and minor volcaniclastic sandstone defined here as the South Thompson Formation (Fig. 3b). The thickness of this unit is variable but is typically on the scale of a couple of hundred metres. Figure. 3. (a) Composite stratigraphic succession in the area of Kamloops, BC.
(b) General stratigraphic column of the Harper Ranch Group and its component formations in the area of Kamloops, BC. (c) General location of measured sections used to construct the composite section of (b). LEGEND Rock Types
limestone
cherty limestone argillaceous
...... ;,,,.._.. sandstone
mudstonewith &aar&stone
Symbols --- rip-up clasts A A cherty
carbonate 0concretions limestone U5 mudstone fl. .. sandstoneR conglomerate - -. -trough cross- :::::: bedding volcanic *I. major unmnformity '<'<.
w bioturbation plant * fragments brachiopods
@$$ fusulinids
conodonts Sub-Formational Units HMPB Harper Mountain Pebble Beds SM ~anzbne Member CM conglomerate Member Unconformably overlying the Tk'emlups and South Thompson formations is a
massive limestone of Permian age here named the McGregor Creek Formation
(Fig. 3b). The McGregor Creek Formation is best exposed in the Lafarge cement
quarry along the South Thompson River (Fig. 2), and is at least 500 m thick. At
several localities, an angular unconformity is exposed between the McGregor
Creek Formation and conglomeratic beds of the Mesozoic Nicola or Rossland
groups.
Tk'emlups Formation
The name Tk'emlups Formation is proposed for the lowermost succession
of strata in the Harper Ranch Group (Fig. 2 unit DMT; Fig. 3a, b). Siliciclastic and
volcaniclastic rocks comprise the most voluminous portion of the Harper Ranch
Group. The majority of the clastic rocks within the Harper Ranch Group occur
within the lower part of the succession, and although volumetrically significant,
these strata have received little attention because of their unfossiliferous
character relative to the carbonates in the area. Due to the lack of knowledge
concerning this succession, rocks of similar lithologic character are rarely
assigned to the Harper Ranch Group outside of the type area.
Tk'emlups comes from the Shuswap language, meaning, "where the waters meet". The people of the Secwepemc Nation used this term to refer to the junction between the North Thompson and South Thompson rivers, which
later became the site of the city of Kamloops. Kamloops is the anglicized version
of the word Tk'emlups. G.M. Dawson first studied rocks belonging to the Tk'emlups Formation in
1876 (Dawson, 1879). At this time, these rocks were assigned to the lower
Cache Creek Complex. Dawson briefly described their lithology as argillites and hard "grauwacke" sandstones with minor greenstone (op. cit. p. 1048). This description was made in the area of Paul Peak, in what is now known to be strata of the Nicola Group (Fig. 2). This description was also applied to rocks cropping out along the South and North Thompson rivers, thus encompassing strata of the
Tk'emlups Formation. Cockfield (1948) provided a more detailed lithologic description of these strata, but again included rocks of the Nicola Group in his description. Cockfield reported these strata to comprise argillite, quartzite, hornstone, conglomerate, and breccia, with associated greenstone, tuff, and agglomerate (op. cit. p. 6).
R.B. Smith was the first to recognize that strata on the western end of
Peter Peak ridge and the southwestern part of the Dome Hills (Fig. 2) belonged in the Upper Triassic Nicola Group (Smith, 1979). Recognition of Nicola Group rocks was based on Late Triassic conodont collections from intercalated thin limestone horizons. He measured 2300 m of strata cropping out along Peter
Peak ridge on the north side of the South Thompson River that was continuous from the faulted contact with the Nicola Group east to the contact with the overlying Late Mississippian limestone (Fig. 2). This section, however, was thought to represent only the lower portion of the Carboniferous strata, which he believed to be more than 5000 m thick (ibid). Smith's section, revisited during the course of this study, forms the basis for the proposed type section of the
Tk'emlups Formation.
Type section and reference section
The most continuous exposures of the Tk'emlups Formation are along the north side of the South Thompson River, east of the city of Kamloops (Fig. 2).
The proposed stratotype is along the eastern end of Peter Peak ridge west of
Harper Ranch Road (Fig. 4; UTM coordinates at base: 699568E, 5618345N).
Here, it is possible to measure a well-bedded sedimentary succession, about
2600 m thick and dipping steeply toward the northeast. The section is readily accessible by driving north along Harper Ranch Road and east along the road that parallels Peter Peak ridge.
In several places, the top of the Tk'emlups Formation is exposed and in conformable contact with the limestone of the overlying South Thompson
Formation. Although the base of the Tk'emlups Formation is either in fault contact with the Nicola Group or covered. The oldest strata of the Tk'emlups
Formation, the Harper Mountain Pebble Beds (Fig. 3b) are not exposed along
Peter Peak ridge, and 2600 m should be considered a minimum thickness for the unit. Smith (1979) reported the presence of Late Mississippian fusulinids from limestone just east of the Dome Hills Fault, suggesting the upper part of
Tk'emlups is repeated at the base (Fig. BP-1).
A reference section for the upper 600 m of the Tk'emlups Formation was measured on the next ridge southeast of the type section (Fig. 4, 5b; UTM coordinates at base: 702091 El 5617747N). This partial section illustrates well op Tk'emlups Fm. ype section Fig. 5a)
base Tk'emlups Fm. Q type section ('~ig.5a) normal fault Quaternary thrust fault ...... 3...... Nicola Group strikeldip .... . of strata (upright) South Thompsor strikeldip of Formation strata (overturned) outcrop station base South' general line of measured section 'base southv I / Thompson Fm. Thompson Fm. Q ... strike parallel offsets of measured ST1 section ST2 section (Fig. 7b) (Fig. 7a) I ... section I 703$l00E I I
Figure 4. Location map for type and reference sections of the Tk'emlups Formation (Fig. 5) and South
Thompson Formation (Fig. 7). See figure 2a for regional location. Figure 5. (a) Tk'emlups Formation type section (section TK1). See Fig. 4 for location (UTM coordinates at base: 699568E, 5618345N). (b) Tk'emlups
Formation reference section (section TK2). See Fig. 4 for location (702091 E,
5617747N) LEGEND
rip-up limestone --4 clasts n...G-:.:- .%I. :+. sandstone discontinuous lamination rnudstone with - loading 9 synsedirnentary (-<-; (-<-; folding Eq rnudstone > 5% allochern content
pyrodastic rich (> 30% pumice) covered R interval AA cherty Graphic Log Grain Size Scale I bioturbation
o0 sand the conformable nature of the contact between the Tk'emlups and South
Thompson formations (Fig. 5b). The contact is exposed at several other localities in the study area, including the south shore of the southwest end of
Paul Lake, above the road on the southwest shore of Pinantan Lake, and along the ridge on the north side of western Paul Lake (Fig. 2).
Definition
The Tk'emlups Formation is an interstratified volcaniclastic sandstone, mudstone, and siltstone unit that is at least 2600 m thick (Fig. 3b). Although relatively unfossiliferous, the Tk'emlups Formation represents deposition from
Late Devonian to Late Mississippian time, constrained by fossil data from basal beds and conformably overlying limestone. The dominant lithologies of the
Tk'emlups Formation comprise volcaniclastic1tuffaceous sandstone, conglomerate/breccia, mudstone, and siltstone. These lithologies are described in terms of a coarser-facies association and a finer-facies association. The type section is typical of the Tk'emlups Formation in that the lower and upper parts are dominated by coarser-facies and the middle part of the formation is dominated by finer-facies.
The coarser-facies consist of medium- to coarse-grained sandstone and tuffaceous sandstone as well as granule to cobble conglomerate and tuffaceous breccia. Grain composition in the sandstone and conglomerate include, in order of abundance, volcanic lithic clasts, pumice, feldspar crystals, chert, mudstone intraclasts, volcanic quartz crystals, and various amounts of calcareous allochems. The most common lithologies of volcanic lithic clasts are: aphanitic andesite, feldspar porphyry andesite, and feldspar-quartz porphyry. Pumice content is variable but generally increases up section, and in some beds comprises the dominant grain type. Individual clasts are generally compressed parallel to bedding, devitrified, and variably altered to chlorite and sericite (Fig.
6A). Rare, silicified pumice clasts are uncompressed and original bubble-wall and tube-wall textures are visible in thin section (Fig. 6A). Mudstone intraclasts are elongate, possibly due to compaction, and are commonly internally bedded.
Mud-clast boundaries are commonly embayed and rarely diffuse. Calcareous allochems are commonly concentrated near the base of sandstone beds and consist mostly of pelmetazoan (stalked echinoderm) ossicles (Fig. 6b).
Transitional beds between the Tk'emlups and South Thompson formations comprise up to 50% calcareous allochems (Fig. 6c).
Coarser-facies occur most commonly as laterally continuous (at outcrop scale) thick- to massive-bedded units with individual beds ranging from 30 cm to
> 10 m thick. Thinner bedded units (<2 m) are generally massive and sharply overlie mudstone/siltstone facies. Thicker units (>2 m) are massive or more commonly display reverse-graded bases, normal-graded tops, and include entrained rip-up clasts of mudstone or interbedded mudstone and siltstone.
Sandstones display poor to moderate sorting and grain size varies from medium- to very coarse-grained sand with pebble-sized clasts. Thicker beds display a greater range of grain sizes, rarely up to cobble size. Moderate relief is present on most basal contacts and relief increases with increased bed thickness. Figure. 6. Thin-section photomicrographs of sandstone (A, B, C) and interbedded mudstone and siltstone of the Tk'emlups Formation. Scale bars represent 1 mm except Dl which represents 1 cm. (A) Coarse-grained volcaniclastic sandstone.
Mudstone (m) and flattened (fp) and silicified pumice (sp) clasts cemented with silica (s) after? calcite. Cross-polarized light. (B) Medium-grained volcaniclastic sandstone. Volcanic rock fragments (v), chert (c), quartz (q), plagioclase- feldspar (f), and pelmetozoan (p) grains. Cross-polarized light. (C) Transitional facies between Tk'emlups and South Thompson formations. Volcanic rock fragments (v), plagioclase-feldspar (f) and abundant pelmetazoan (p) grains cemented with calcite. Cross-polarized light. (D) lnterbedded mudstone and siltstone. Relict radiolarians (r) apparent in darkest mudstone laminae. Siltstone beds display current ripples (cr) and erode and deform underlying mudstone.
Plane light.
Scours, as well as load and flame structures are evident at most basal contacts.
Thicker units commonly fine upwards, are planar laminated in their upper parts, and are gradational with overlying mudstone and siltstone.
The finer-facies consist of massive to laminated, variably pyritic, grey to black mudstone, which contains a variable proportion of discrete, interbedded siltstone and fine-grained sandstone beds. The latter are generally sharp based, massive- or normal-graded, and display poorly developed ripple cross-lamination typical of low-density turbidity currents (Fig. 6d; Middleton and Hampton, 1973;
Smith, 1979). Siltstone and fine-grained sandstone interbeds range from very thin (1 mm) to thick (>50 mm). In rare cases turbiditic layers contain <2 mm diameter rip-ups of the underlying mudstone at their bases. Soft sediment deformation is apparent in most exposures in the form of loads, flames, and synsedimentary folds.
Fossils are rare within the Tk'emlups Formation, consisting mostly of echinoderm (crinoid) molds within siltstone interbeds. Unidentified brachiopod molds were found in mudstone from one locality and likely represent an in situ fauna. Rare trace fossils, including Planolites, Palaeophycus, Helminthopsis, and
Lorenzia, occur throughout the mudstone and siltstone beds.
At a single locality cropping out along the road on the north flank of Harper
Mountain is a thin succession of siltstone, sandstone, sandy bioclastic limestone, and chert pebble conglomerate referred to here as the Harper Mountain Pebble
Beds (Fig. 2, 3b). Conodonts from these beds indicate an age of latest Devonian
(Late Famennian) (Danner and Orchard, 2000), making these the oldest known strata in the Harper Ranch Group. The Harper Mountain Pebble Beds comprise mostly buff to orange-brown weathering siltstone and fine- to medium-grained sandstone with rare beds of sandy bioclastic limestone. Rare bioclastic beds occur near the base of the outcrop, and sandstone beds thicken and coarsen upward. Sandy chert and volcanic-lithic pebble conglomerate marks the apparent top of the section. Fossil plant debris is common in the upper part of the succession. Mudstone and siltstone, cropping out nearby on the south side of the road, are inferred to disconformably overlie the pebble beds.
Fauna
The Tk'emlups Formation is relatively unfossiliferous. Important fossil faunas have been recovered from the Harper Mountain Pebble Beds and from a horizon of calcareous nodules occurring near the base of the disconformably overlying mudstone. Collections (B-124, Appendix D) made from a conglomerate of unknown stratigraphic position produced the Lower Famennian conodonts
Palmatolepis minuta and P. delicatula representing the P. triangularis zone.
Although not in stratigraphic context, these conodonts provide insight into the age of the base of the Harper Ranch Group. Unidentified brachiopods and fossil plant fragments recovered from mudstone strata of the Tk'emlups Formation are of minor age-diagnostic significance.
Fossils recovered from the Harper Mountain Pebble Beds were most recently reported (Danner and Orchard, 2000) as: the brachiopods cf. Cyrtiopsis spp., cf. Cyrtospirifer sp., cf. Eochoristites protistus, cf. Floweria sp.,
Rhyssochonetes sp., and cf. Sinotectirostrum banffense banffense; the gastropod Loxonema sp.; the ostracod Bairdiocypris sp.; and the conodonts
Apatognathus varians varians, Bispathodus sp., lcriodus costatus darbyensis,
Palmatolepis sp., and Polygnathus spp. This association has been interpreted as shallow water, high-energy fauna (Orchard, 1987). Recent collections have produced a single identifiable specimen of Palmatolepis gracilis sigmoidalis, placing the fauna within the Pa. expansa Zone of the Late Famennian (M.J.
Orchard, pers. comm. 2002). Additionally, large fragments of unidentified plant material (lycopsids?) are scattered throughout the Harper Mountain Pebble Beds, implying the presence of a vegetated hinterland.
A conodont fauna collected from carbonate concretion bearing mudstone occurring near the base of the Tk'emlups Formation includes forms indicative of the Lower Tournaisian (Lower Mississippian) Siphonodella duplicata Zone.
Individual conodont elements present are: Siphonodella duplicata, Siphonodella sp., Bispathodus stabilis, Polygnathus communis carina, P. inornatus, P. vogesi,
Pseudopolygnathus fusiformis, and Ps. sp. This faunal association, unique in the
Canadian Cordillera, has been interpreted as an outer shelf biofacies (Beatty,
2002). Small fragmentary plant fossils (filicopsids?) rarely occur in mudstone throughout the Tk'emlups Formation.
South Thompson Formation
An approximately 300 m thick succession of massive to well bedded, mostly carbonate rocks crop out discontinuously throughout the central part of the study area. The name proposed for these strata is the South Thompson
Formation. In the type area, the South Thompson Formation comprises an upper and lower carbonate succession locally separated by a series of volcaniclastics and in turn overlain by a polymictic conglomerate. The limestones of the South
Thompson Formation form prominent northwest-trending ribs, best exposed along the north side of the south Thompson River (Fig. 2). Other significant exposures occur on Harper Mountain, south of Heffley Lake, and in the northern part of the Dome Hills (Fig. 2).
The South Thompson Formation is named for the South Thompson River, the southern tributary of the Thompson River, which flows west through the city of Kamloops parallel to the Trans-Canada Highway. The explorer Simon Fraser, in honour of the Canadian explorer David Thompson, named the Thompson
River.
In the Kamloops area, rocks belonging to the South Thompson Formation were first described by G.M. Dawson (1879). He reported on limestones that were "rarely more than a few hundred feet in thickness and often much less" as well as a large outcrop of limestone nearly a mile wide, all of which he included in the lower Cache Creek Complex. Although he did not make detailed lithological descriptions of these strata, he noted that large crinoids (> 2.5 cm diameter ossicles) and "fusulinae"(p. 42B) were common lithologic components. This succession was assigned to the Carboniferous (Dawson, 1896).
R.A. Daly (191 5) measured sections from Paul Peak east past the present location of the Lafarge Quarry to the Permian- Jurassic unconformity (Fig. 2).
Measurements of 800 ft (-240 m) and 500 ft (-1 67 m) were reported for limestone outcrops along the western and middle part of this section. These are assumed to be equivalent to the TKI and ST2 sections respectively (Fig. 4).
Daly noted the occurrence of 90 ft (-27 m) of "volcanic ash and agglomerate in the middle" of the 500 ft thick limestone (op. cit. p.120), which leaves little doubt this is the ST2 section (Fig. 7, 75 m). Daly documented the occurrence of brachiopods (Productus cora) and unidentified radiolarians from this outcrop, and confirmed the Carboniferous age of these strata.
Cockfield (1948) mapped many of the exposures of the South Thompson
Formation (Map Unit Ia, Cockfield, 1948). He did not differentiate Permian limestone of the McGregor Creek Formation on his map, referring to it in his notes as the "upper limestone member" of the succession. Extensive fossil collections were made from the South Thompson Formation during Cockfield's study, many of which provided Mississippian ages (op. cit. p. 9 -10). Based on these Early Carboniferous fossils, Cockfield questioned the correlation of the strata in the Kamloops area with that in the Marble Canyon area, and thus their inclusion in the Cache Creek Complex.
Smith (1979) included the South Thompson Formation within his lower
Harper Ranch succession. He divided the carbonates that occur along Peter
Peak Ridge into two units (Units 1A and IB, Smith, 1979), separated by over
2300 m of clastic strata. Recovery of Mississippian-age brachiopods from Unit
1A (Dutro in Smith, 1979) led to this interpretation. Unit 1B limestones were at the time regarded as Pennsylvanian from previous studies (Sada and Danner,
1974,1976). Given the lithology, faunal components (Smith, 1979, p. 16) and close proximity of Smith's Unit 1A to the fault separating the Nicola and Harper Ranch groups, it is here interpreted as a structural slice of the South Thompson
Formation.
Composite Type Section
The South Thompson Formation is best exposed along a series of terraces on the north side of the South Thompson River, northeast of the city of
Kamloops (Fig. 2). The type, reference, and composite sections of the
Tk'emlups Formation and the Harper Ranch Group occur in this same outcrop belt. Fossil localities from past studies of the Harper Ranch Group were located mostly in this area (Sada and Danner, 1974,1976). Two of those localities,
"South Thompson No. 1" and "South Thompson No. 2", form the basis of the
South Thompson Formation composite type section presented in this paper. The
South Thompson No. 1 (ST1 section, Fig. 4) locality is situated approximately 1 km south of the Harper Ranch house, on the south side of the ridge that separates the ranch from the South Thompson River (Fig. 2; UTM coordinates at base 702912E, 5617137N).
The base of this section coincides with the top of the reference section of the Tk'emlups Formation (TK2 section Fig. 4). There, the conformable nature of the contact between the Tk'emlups and South Thompson Formations is well exposed and this is designated as the base of the composite type section (Fig.7).
The ST1 section is believed to encompass the entire succession of the South
Thompson Formation. However, a large, mostly covered interval in the middle of the section obscures much of the Sandstone Member and upper carbonate succession. Sporadically distributed outcrops within the mostly covered interval, comprising volcaniclastic sandstone, calcareous sandstone, limestone cobble conglomerate, and siltstone, are referred to the Sandstone Member of the formation. Stratigraphically high in the mostly covered interval of the ST1 section is a succession of purple sandstone and siltstone, interbedded with rare green siltstone containing apparent soil peds, which is considered to be correlative with the paleosol occurring at metre 114 of the ST2 section (Fig. 7). Overlying the
Sandstone Member a thin succession of algal laminated limestone crops out within a mostly covered interval. This is regarded as equivalent to the upper carbonate succession of the formation (Fig. 7, 136 m).
A succession of limestone cobble conglomerate, volcaniclastic sandstone, and polymictic cobble conglomerate overlies the upper carbonate, although the contact is obscured. This succession represents the most complete exposure of the Conglomerate Member of the South Thompson Formation (Fig. 3b, 7b).
The South Thompson No. 2 (ST2) locality is approximately 1100 m east of
STl, along the same ridge (UTM coordinates at base 704468E15617206N). The rocks between the two sections are mostly interbedded mudstone and volcaniclastic sandstone and conglomerate included in the Tk'emlups Formation.
The structural feature that repeats the South Thompson and upper Tk'emlups formations was not observed (Fig. 2). Although the base of the ST2 section is covered, the attitude of the underlying Tk'emlups Formation coincides with that of the South Thompson Formation and the contact is considered conformable. The
ST2 section includes excellent exposures of both the upper and lower carbonate successions of the South Thompson Formation, as well as the intervening
Sandstone Member.
Definition
The South Thompson Formation is a predominantly carbonate succession marked by volcaniclastic sandstone and conglomerate interbeds. This unit ranges from 4 0 metres to >200 metres thick, although both base and top are rarely exposed. Where well exposed, the limestones of the South Thompson
Formation may be divided into an upper unit and lower unit (Fig. 7). These two units do not differ lithologically or biostratigraphically, and are recognized based on the presence of the intervening Sandstone Member of the South Thompson
Formation.
The carbonate lithologies of the South Thompson Formation, described using the Dunham classification (Dunham, 1962), are predominantly bioclastic limestone, specifically, skeletal-peloidal wackestone, crinoidal packstone, fusulinacean packstone, brachiopod packstone, skeletal-peloidal grainstone, and more rarely, spicular mudstone. The limestones of the South Thompson
Formation are predominantly medium grey to light grey-brown weathering, dark grey to light grey fresh, and massive to thin-bedded. Abundant allochems include brachiopods, pelmetozoans, bryozoans, fusulinids and peloids.
Additional fossil constituents of these rocks include rugosan and tabulate corals, gastropods, ostracodes, and rarely, ammonoids. Large partially articulated crinoid columnals up to 3 cm in diametre are considered a characteristic feature of this unit (W.R. Danner pers. comm., 1999; Dawson, 1879). Figure 7. South Thompson Formation composite section (section ST1 :
Conglomerate Member; Section ST2: lower carbonate unit, Sandstone Member, upper carbonate unit). See Fig. 4 for location (UTM coordinates at base STI:
702912E, 56171 37N; UTM coordinates at base ST2: 704496E, 56171 81 N). ST#2 Section 209 Q 200
unit
Sandstone Member
1 LEGEND rock type symbol
limestone trough cross- bedding
A chert nodules chert pebbles argillaceous @ limestone plant fragments lower * brachiopods
g corals conglomerate crinoids (>5% denotes content mudstone 8 in sandstone)
Grain Scale Grain Scab ii ;aIttyyte,sII S~l~c~clasCcs wwwww : 6 55555 m~m~w ow ZIIBH ;ZkE,??EE 6 $ aa.gg5 gs ;s as E ig&,= .' sand lnterbeds (10 to 30 cm thick), of medium-grained, volcaniclastic sand are rarely present in the smaller (10's metres thick) outcrops, although the stratigraphic positions of these are uncertain.
Six carbonate microfacies are recognized in the South Thompson
Formation, four from the lower carbonate unit, one from the Sandstone Member, and one from the upper carbonate unit. These are considered representative of the majority of carbonate facies that occur in the formation. Descriptions are based on analyses of 17 thin sections. Sampling density was such that only broad vertical facies successions may be discussed. Lack of outcrop continuity inhibited determination of lateral facies successions. Microfacies are presented in general stratigraphic order and broadly represent their distribution within the
ST2 section.
Microfacies A (Fig. 8A) is spicular lime-mudstone. In outcrop, this facies is represented by massive bedded, hard, dense, dark grey, micritic limestone. Very rare skeletal debris consists exclusively of the ammonoid Goniatites crenistria
(Beatty, 2002). Conodonts, representative of the Gnathodus bilineatus Zone
(sensu lato) have also been recovered from this limestone. In thin section, microfacies A consists of siliceous sponge spicules and relict radiolaria disseminated in a mottled (peloidal?) partially recrystallized lime-mud matrix.
The representative sample was collected from approximately 1 m above the contact between the Tk'emlups and South Thompson formations, just south of
Pinantan Lake (Fig. 2). Fig. 8. Thin-section photomicrographs of representative limestone microfacies of the South Thompson Formation. Approximate stratigraphic levels of samples are shown in Fig. 7. Plane light. All scale bars represent 2 mm. (A) Spicular lime- mudstone. Lower carbonate unit, 1 m above contact with Tk'emlups Formation.
Sponge spicules (s) and relict radiolaria (r) in micrite matrix. (B) Brachiopod - foraminifer packstone. Lower carbonate. Abundant productid brachiopod shells
(b) and spines (s). (C) Foraminifer - fusuline - peloidal wackestone. Lower carbonate unit. (D) Algal - laminated micrite. Silty micrite with crypto-microbial crusts (c) and dispersed feldspar crystals (9. Top of lower carbonate. (E) Coarse grainstone composed of intraclasts (i), skeletal debris and peloids, some of which are micritized ooids (0). Sandstone Member. (F) Peloid grainstone. Upper carbonate unit. Spar cemented peloids.
Microfacies B (Fig. 8B), brachiopod - foraminifera1 packstone, consists of
large (2 mm - > 50 mm) brachiopod shell debris, as well as smaller foraminifers,
and rarely large foraminifers (fusulinaceans) set within a lime-mud matrix.
Fusulinids are variably micritized. Skeletal elements are dominated by thick-
shelled productid brachiopod debris including abundant hollow spines. In
outcrop, brachiopod debris forms common 10 - 20 cm thick beds throughout the
lower carbonate unit and rarely within the upper carbonate unit. Brachiopods are for the most part disarticulated, although there is minimal evidence for transport
or current agitation demonstrated by the generally well-preserved nature of both
shells and spines as well as the abundance of lime-mud.
Microfacies C (Fig. 8, C), foraminifer-peloidal wackestone - packstone, is
similar to microfacies B, however there is a marked absence of large unbroken
brachiopod shells. Dominant allochems include abundant, fine-grained, small foraminifers and peloids disseminated in a mudstone and sparite matrix.
Foraminifers are generally well preserved and filled with spar. Peloids are round
or ellipsoid, and cemented with calcite spar or mudstone. Subcircular or ellipsoidal areas of greater spary cement concentration may indicate burrowing, although, unequivocal evidence of bioturbation is lacking.
Microfacies D (Fig. 8D) comprises algal - laminated lime-mud and silty
lime-mud. This facies differs from the other five microfacies in its marked absence of recognizable allochems and the presence of cryptalgal crusts. Crusts are very thin, crinkled and curved, possibly approaching domed. Clastic grains, consisting of quartz-silt and very rare twinned feldspar crystals, are concentrated in areas of intense sparite cementation. These areas may correspond to inter- dome depressions. This facies occurs as a single bed at the top of the lower carbonate unit, below the Sandstone Member (Fig. 7, 77 m) as well as within the upper carbonate unit of the ST1 section.
Microfacies E (Fig. 8E) comprises medium- to coarse-grained, moderately to poorly sorted skeletal-intraclast grainstone. Allochems include brachiopods, crinoids, fusulinids, and ooids set in sparite cement. Most allochems have well developed micrite envelopes. lntraclasts are coarse-grained and subangular, consisting mostly of microfacies C and F. Coarse, subrounded quartz grains are also present. In some samples, bedding is apparent from the alignment of elongate grains or rarely by concentrations of fine-grained opaque grains
(magnetite?). In outcrop, rocks belonging to this facies are typically trough cross- bedded. This facies occurs exclusively in the upper part of the Sandstone
Member (Fig. 7, -120 m).
Microfacies F (Fig. 8F), peloidal grainstone, is most common in the upper carbonate unit. It is moderately to poorly sorted and fine- to medium-grained with abundant peloids cemented by sparry calcite. Peloids are round to ellipsoidal and rarely embayed. Silt-sized quartz is rarely embedded along their margins.
Many peloids appear to have concentric rims of lighter (less dense) lime-mud surrounding darker centres. These may be relict ooid textures or reaction rims developed during cementation. Rare occurrences of oolite were noted from both the upper and lower carbonate unit and are regarded as a sub-facies of F. The environmental setting of the carbonates of the South Thompson
Formation is predominantly open marine indicated by microfacies A, B, C, E, and
F. The sponge spicule - radiolaria association of microfacies A suggests deep- water and a basinal or lower flank environment. The association with clastic mudstone of the Tk'emlups Formation below and shaley marlstone above F in outcrop support this interpretation. Microfacies B, C, E, and F are referred to the middle shelf environment of Wilson and Jordan (1983). Normal salinity conditions and depths largely within the photic zone characterize this environment.
Microfacies B, with its abundance of apparently monospecific brachiopods suggests biostromal deposition, and may, in places, be referred to as mud-rich bafflestone (sensu Watkins, 1993). Microfacies C is the most volumetrically significant facies, and because of the abundance of lime-mud, represents deposition below normal wave base or within a protected low-energy environment such as a lagoon. Microfacies F represents well-washed deposits indicative of higher-energy conditions such as a carbonate sand bank or shoal. lntraclast grainstone of microfacies E represents the shallow subtidal zone.
Wave action reworked packstone and wackestone from adjacent low-energy environments and mixed these intraclasts with abundant endolithic algae coated skeletal grains. Quartz and magnetite (?) grains are rarely hydrodynamically concentrated along bedding planes, although quartz grains are more commonly disseminated (Fig. 8E). Abundant cryptalgal structures imply microfacies D represent inter-tidal or tidal flat conditions of the inner shelf. Absence of allochems may suggest abnormal salinity and lack of current structures or rip-up clasts implies low energy conditions. Clastic detritus is likely wind blown and
bound by algal mats during low tide exposure. The facies succession from
basinal (Microfacies A) to middle shelf (Microfacies B and C) to inner shelf
(Microfacies D) environments implies a generally shoaling upward trend in the
lower carbonate unit. This trend continues through to the upper part of the
Sandstone Member where an apparent paleosol is developed (Fig. 7, 114 m).
Sampling from the upper carbonate unit is too sparse to provide comparable
interpretations.
The Sandstone Member of the South Thompson Formation is best
exposed between 77 m and 136 m of the ST2 section (Fig. 7). Here, massive
volcaniclastic sandstone, red argillaceous mudstone, cross-bedded grainstone,
and limestone cobble conglomerate overlie mudstone of the lower carbonate
unit. This mixed marine and non-marine clastic-carbonate unit is present in
several exposures of the South Thompson Formation, including ST1, ST2, and
the north side of Paul Lake (Fig. 2). Common to all exposures of the Sandstone
Member are red- to purple-coloured sandstone and mudstone, suggestive of
subaerial exposure and oxidation (Johnson et a/., 1997).
In the ST2 section (Fig. 7), the Sandstone Member comprises massive fine- to medium-grained sandstone, more than 30 m thick, overlying algal-
laminated lime-mud of the lower carbonate member. The sandstone is overlain
by well-bedded silty mudstone and, in turn, by massive nodular mudstone. The contacts are apparently gradational. The massive nodular mudstone displays
soil peds and, in thin section, root molds. This is interpreted as a paleosol. The mudstone is overlain with trough cross-bedded calcareous sandstone grading up into sandy grainstone and intraclast grainstone (microfacies E). The contact between the mudstone and trough cross-bedded sandstone is scoured.
Overlying the intraclast grainstone is 15 m of limestone conglomerate fining upward from cobble to pebble size. Cobble lithologies include grainstone, packstone, and wackestone, as well as well-rounded chert pebbles. Chert pebbles become increasingly more abundant up section. The fusulinids
Mediocris breviscula and Pseudoendothyra columbiana were identified in thin section from a single cobble (sample 00-OF-B-ST-26b, Appendix B), and are typical of those found throughout the South Thompson Formation (see Appendix
B). The upper contact of the Sandstone Member is obscured by cover, although it is likely gradational with the overlying upper carbonate unit.
The upper carbonate unit of the South Thompson Formation comprises grainstone, packstone, wackestone, and minor mudstone indistinguishable from those of the lower carbonate unit. Additionally, conodonts and fusulinids recovered from this unit represent faunas identical to those from the lower unit. It is recognized solely on its stratigraphic position above the Sandstone Member.
Systematic sampling is likely required to better characterize the lithology of upper carbonate unit and therefore distinguish it from the lower unit.
The Conglomerate Member of the South Thompson Formation is a succession of polymictic pebble to cobble conglomerate interbedded with volcaniclastic sandstone and siltstone (Fig. 7). These strata are included in the
South Thompson Formation based on the presence of endothyrid foraminifera in limestone cobbles identified in the field. The type exposure is 62 m thick and forms the top of the ST1 section. The Conglomerate Member has not been
identified outside of the type section, however, conglomerate of similar lithology
crops out within the belt of Harper Ranch Group rocks.
Pebble and cobble lithologies comprise limestone, siltstone, volcanic
lithics, and chert. Limestone cobbles are well rounded and commonly elongate,
consisting primarily of lime mudstone. Siltstone clasts are well rounded, massive,
and typically light grey-green in colour. Volcanic lithics are typically well-rounded
purple or green aphanitic or porphyritc (feldspar) andesite. Rare boulders of welded tuff are up to 40 cm in diametre were observed. Chert cobbles and
pebbles have fresh and weathered colours of dark grey or black. Surfaces of several chert clasts display molds of crinoid ossicles suggesting they are
reworked silicified limestone nodules from the underlying carbonate.
Conglomerate matrix ranges from fine- to coarse-grained volcanic-lithic sandstone.
Conglomerate beds range from 0.5 m to 6 m thick and most are normally graded. Basal contacts are sharp to scoured and, at outcrop scale, show up to
50 cm relief. Limestone clasts are typically concentrated at the bases of normally graded beds, but distributed throughout massive beds. Most conglomerate beds fine upward and are gradational with overlying sandstone and siltstone. Some appear to be amalgamations of several discrete beds. Sandstone beds are massive or planar bedded and rarely contain carbonaceous material and coarse- grained pyrite. Most sandstone beds grade into siltstone. Siltstones range from purple to green in colour, typical of oxidation - reduction conditions. Rare
discontinuous very fine-grained limestone lenses are intercalated with the siltstone and sandstone. These limestone lenses are apparently devoid of fossils.
Fauna
Limestones of the South Thompson Formation are, for the most part, fossiliferous, containing abundant macro- and microscopic groups represented in a variety of carbonate lithologies. These include the macroscopic coral,
brachiopod, bryozoan, and ammonoid groups, and the microscopic foraminiferal, conodont, algal, and ostracod groups. Of these groups, collections are biased toward conodonts and large foraminifers (fusulinaceans) for the purpose of
biostratigraphic refinement.
Macrofossils from the South Thompson Formation were most recently reported as, the brachiopods: Titanaria sp., Striatifera sp., lnflatia sp., and
Flexaria sp. (Dutro in, Danner and Orchard, 2000); the corals: Hexaphyllia sp.,
Hapsiphlyllum sp., Syringopora sp., Lophophyllum sp., Cyanthophyllum sp.,
Aulopora sp., and Lithostrotion sp. (Danner and Orchard, 2000; Bamber, 2002); and the ammonoid: Goniatites crenistria (Beatty, 2002). Gastropod and bryozoan collections have not been identified.
The South Thompson Formation has been the subject of several studies focusing on foraminifers (Sada and Danner, 1974; 1976). Of the collections studied, most were assigned Pennsylvanian ages (ibid). Subsequent studies focusing on conodont microfossils provide a revised age of Late Mississippian for the South Thompson Formation (Orchard, 1987; Danner and Orchard, 2000;
Beatty, 2002, this study). Rui (2001), as part of this study, examined 46 carbonate thin sections from this unit. The following fusulinids were commonly present in samples of the South Thompson Formation: Mediocris breviscula,
Eostaffella cooperi, Pseudoendothyra columbiana, Mediocris cupellaeformis,
Millerella spp., and Mediocris spp. A complete list of species identified is presented in Appendix B.
Orchard reported the following conodonts from several localities of the
South Thompson Formation (Orchard, 1987; Danner and Orchard, 2000):
Gnathodus bilineatus, G. homopunctatus, Vogelgnathus campbelli, Hindeodus sp., and Kladognathus sp., which he called the Pinantan Lake fauna and regarded as late Visean to early Namurian (Orchard, 1987 p. 746). Ostracods, isolated from the light fractions of conodont samples, which were separated by the use of heavy liquids, were assigned Pennsylvanian ages (Crasquin-Soleau and Orchard, 1994). Ages determined from ostracods recovered from the South
Thompson Formation however, cannot be reconciled with those made from all other fossil groups and are disregarded in this study.
Conodont collections made for this study have replicated those of Orchard
(1987) as well as contributing the additional specimens Gnathodus girtyi and
Lochreia nodosa. These additional specimens, as well as conodont-ammonoid associations from the base of the South Thompson Formation, indicate an age of
Serpukhovian (Late Mississippian) for the succession. A complete list of conodonts recovered from the South Thompson Formation during the course of this study is presented in Appendix D.
McGregor Creek Formation
The uppermost succession of carbonate rocks in the Harper Ranch Group comprises massive to well-bedded limestones, commonly marked by secondary chert beds or nodular chert horizons. The name McGregor Creek Formation is given to this succession.
The McGregor Creek Formation generally crops out as massive units in the eastern part of the study area (Fig. 2, unit PMC) where it unconformably overlies the Tk'emlups and South Thompson formations. Where recognizable, bedding is generally oriented either northwest - southeast or northeast - southwest, with dips moderately to steeply to the east. In the southeast portion of the study area, the McGregor Creek Formation crops out as a series of east- west trending terraces, from the lowermost of which the Canada Lafarge Cement
Company extracts itsraw materials. Exposures within the quarry form the best examples of the stratigraphy of the unit, but the transient nature of these outcrops precludes their designation as type sections.
The McGregor Creek Formation is named for McGregor Creek, a south- trending drainage in the southeast part of the map area. McGregor Creek passes between the two largest.exposures of the McGregor Creek Formation in the southern part of the map area (Fig. 2).
Dawson first reported rocks of the McGregor Creek Formation from fieldwork done in 1876 (Dawson, 1896). He, as well as subsequent workers (e.g. Daly, 1915, and Cockfield, 1948), did not differentiate them from other rocks of the "Cache Creek succession" in the area. Both Daly (1915) and Cockfield
(1948) reported fossils of Permian age from the large outcrop of the McGregor
Creek Formation near what is now the Lafarge Quarry. These age interpretations reinforced erroneous correlations with the Marble Canyon Limestone of the
Cache Creek Complex (ibid). Sada and Danner (1974) provide a sketch geologic map covering the southeast part of the present study, in which Permian limestones are differentiated from those of Carboniferous age.
On both the east and west margins of the Harper Ranch Group outcrop belt, limestone boulders and cobbles of Lower Permian age are incorporated into conglomerates assigned to the Nicola Group (unit uTrNc, Fig. 2). Locally, these conglomerates are developed on top of masses of carbonate interpreted as
McGregor Creek Formation
The McGregor Creek Formation is fossiliferous and has been the subject of several studies concerning its faunal composition and more specifically the relation of these fauna to those of contemporaneous strata on the North
American margin (Nelson and Nelson, 1985; Miller, 1987; Orchard and Forster,
1988; Belasky and Runnegar, 1994; Belasky et a/., 2002). Lithologic descriptions however, are rarely provided (one exception is Orchard and Forster, 1988). This study constitutes the first attempt to characterise the lithology of the McGregor
Creek Formation since the work of Orchard and Forster (1988). Type Locality and Section
The best exposures of the McGregor Creek Formation occur in and around the Lafarge Quarry on the north side of the South Thompson River, and therefore the area is regarded as the type locality of the formation (Fig. 3c). The quarry is situated within a relatively continuous belt of Permian limestone approximately 1200 m wide and over 2000 m long (Fig. 2). To the west, limestones and siliciclastics of the South Thompson and Tk'emlups formations underlie the McGregor Creek Formation. To the east, it is overlain with angular unconformity by siltstones and conglomerates of the Rossland Group (Fig. 2).
Other exposures of the McGregor Creek Formation are moderately to highly recrystallized and scattered throughout the eastern part of the Harper Ranch
Group outcrop belt. Neither the stratigraphic base nor top of the formation was observed during the course of the study.
Within the Lafarge Quarry, it is possible to measure well-bedded limestones of the McGregor Creek Formation, although folding and faulting is pervasive. Previous study of this outcrop outlined structural repetition within the quarry due to both folding and faulting (Orchard and Forster, 1988).
Paleontological (Nelson and Nelson, 1985) and biostratigraphic (Orchard and
Forster, 1988; Bamber, 2002) studies of the unit have defined an age range for the McGregor Creek Formation of Asselian to Wordian (Lower to Middle
Permian). The type section of the unit however is of Sakmarian to Kungurian? age (Orchard and Forster, 1988) implying that the youngest and oldest strata are absent from the type section. No stratigraphic marker horizons were recognised from this unit during the course of this or previous studies. Due to structural 48 Figure 9. (A) McGregor Creek Formation type section (section MCI). UTM coordinates at base: 706430E, 5617713N. (B) Location map for type section of the McGregor Creek Formation. limestone limestone with chert interbeds A chert nodules I p corals
Graphic Log Grain Size Scale
outh Thompson Fm.
561 8OOON- McGregor Creek Fm.. I
%... %... strike parallel offsets of ,' measured section
6-9outcrop station i107000E complexity and lack of marker horizons, recognition of continuous stratigraphic successions within the McGregor Creek Formation is currently dependent upon biostratigraphic indices, many of which require microscopic study. The type section of the McGregor Creek Formation is immediately west of the Lafarge quarry (Fig. 9; UTM coordinates at base: 706430E, 5617713N) the top part of which corresponds to section "L" of Orchard and Forster (1988, p. 35). This section is the westward continuation of the highest tier of the present day quarry.
It is selected because it is not involved in quarry operations to date, and represents one of the most biostratigraphically complete sections of the formation
(ibid). Access to the type section is gained from the western end of the quarry, although permission of the Canada Lafarge Cement Company is required.
The base of the section corresponds to the westernmost outcrop of limestone along a mostly continuous east-west oriented terrace that terminates eastward in the Lafarge Quarry. Exposure of the formation ranges from poor to moderate and covered intervals comprise less than 50% of the total outcrop length. Outcrop is typically patchy, expressed as low relief hills, but is locally better exposed in gullies. Most bedding attitudes were obtained using chert interbeds and due to their likely early diagenetic origin, some caution should be taken when interpreting structural trends from these data. Folding is apparent in several places along the section, most notably at outcrop station B-9 (Fig. 9B;
Appendix E). However, most bedding attitudes are reconcilable with the general trend of the section. Way-up indicators are not readily observable, however biostratigraphic data from Orchard and Forster (1988) indicate eastward younging. Consequently, the section is not overturned. The top of the section was chosen as the eastern-most limestone outcrop west of the Lafarge Quarry.
A fault, inferred from the repetition of conodont fauna, is delineated here
(Orchard and Forster, 1988).
Definition
The McGregor Creek Formation comprises massive bedded, grey brown to light grey weathering, limestone interbedded with less common continuous or lensoid, dark grey to black secondary chert beds. Crinoidal packstone and wackestone containing brachiopods, fusulinaceans and other foraminifera, tabulate corals, bryozoans, and gastropods are typical of the unit. Spicular lime- mudstones occur locally. Cryptalgal laminated lime-mudstone is present at one locality, but there the stratigraphic context is unknown. Fusulinid packstone to grainstone occurs locally, but was not observed along the type section.
Chert nodules are common throughout the unit and some reach diameters of 150 cm. Daly (1915) reported radiolaria in chert nodules, observable in thin section from the type locality of the formation. Nodules and interbeds of chert are present in places in the South Thompson Formation as well, but there they are of relatively reduced size and volume. Thus, on the scale of large outcrops, the common presence of chert nodules and silicified limestone beds might be considered a diagnostic feature of the McGregor Creek Formation.
The McGregor Creek Formation is devoid of clastic detritus coarser than silt. Locally however, the unit is argillaceous, and where so, typically thinly bedded. The lack of volcanic detritus implies the prior denudation of the volcanic hinterland that was present during deposition of both the Tk'emlups and South
Thompson formations. The relatively slow rate of deposition of the McGregor
Creek Formation (500 m over ca. 40 Ma) and its diverse and abundant calcareous fauna, together imply a stable open marine platform sheltered from direct input of clastic sources.
Conodonts, fusulinaceans, and corals recovered from this unit constrain its age to Asselian to ?Wordian (Nelson and Nelson, 1985; Orchard and Forster,
1988; Bamber, 2002; this study). Limestones of Artinskian (late Wolfcampian) and Sakmarian (early Leonardian) age however are the most voluminous
(Orchard and Forster, 1988).
Fauna
Fossils are abundant in the McGregor Creek Formation, and are represented by a diverse micro- and macro-fauna throughout the unit. Numerous previous studies on the paleontology of the unit have resulted in an extensive list of taxa. Key taxa from major fossil groups are summarized below. More complete inventories are provided in references cited for each group.
The most significant groups of fossils from the perspectives of biostratigraphy and paleobiogeography comprise the conodonts: Adetognathus paralautus, Sweetognathus inornatus, S. whitei, Neogondolella bisselli, Ng. idahoensis, Diplognathodus augustus, Neostreptognathodus pequopensis, Ns. ruzhencevi, Ns. sulcoplicatus, Hindeodus sp (Orchard and Forster, 1988); the fusulinids: Pseudoschwagerina skinneri, Pseudofusulina danneri,
Pseudfusulinella danneri, Parafusulina armstrongi, Parafusulina thomassoni, and Boultonia sp. (Danner and Orchard, 2000); the corals Waagenophyllum,
Petalaxis sp. cf. P. sutherlandi, and Lytvophyllum sp. indet. (Danner and
Orchard, 2000; Bamber, 2002); the ammonoids Agathiceras suessi, and
Neocrimites warreni. B rachiopods, bryozoans, gastropods, and ostracodes have also been collected and studied from this unit (e.g.. Crasquin-Soleau and
Orchard, 1994), but are presently of less biostratigraphic significance and, therefore, not listed here.
Depositional History
The stratigraphic succession of the Harper Ranch Group in the Kamloops,
B.C. area records the nascent state and filling of an island-arc marginal basin and the subsequent establishment of a carbonate platform. Pebbly sandstones
(Harper Mountain Pebble Beds) (Fig. 10A) represent shoreface deposits recording erosion of deep-water sediments (radiolarian chert). This might be due to uplift from thermal doming associated with initial island-arc activity (Larue et al., 1991). Tournaisian-age deeper-water deposits document the establishment of a large marginal island-arc basin that abruptly overlies initial shoreface deposits. Coincident with basin development, increased volcanism is inferred from deposition of abundant debris flows of volcaniclastic origin (Fig. 10B). The
Tklemlups Formation embodies the early history of this volcanic centre, although, due to the absence of volcanic flows, only represents the distal part of this deposystem. Figure 10. Block diagrams schematically depicting deposition of Harper Ranch
Group interpreted from type sections. Heavy lines on (B), (E), and (F) indicate relative positions of measured sections in Figs. 5, 7, and 9. (A) Uplift of oceanic sediments and deposition of Harper Mountain Pebble Beds, arc edifice slightly emergent. (B) Deposition of main part of Tk'emlups Formation, arc edifice greatly emergent, sedimentary reworking of volcanics and continued volcanism. (C)
Volcanic quiescence, initial deposition of South Thompson Formation. (D)
Relative sea level fall, deposition of Sandstone Member of South Thompson
Formation. (E) Tectonic uplift, denudation of arc edifice, Tk'emlups and South
Thompson formations coincident with deposition of Conglomerate Member of
South Thompson Formation. (F) Transgression, deposition of McGregor Creek
Formation. Late Famennian Tournaisian - late Visean
late Visean - Serpukhovian Serpukhovian
post Serpukhovian Lower - Middle Permian The transition between the Tk'emlups and South Thompson formations signifies a change in depositional regime, resulting from the uplift of the basin into the euphotic zone, the cessation of volcanism, and consequent establishment of environments favouring carbonate deposition in the Late
Mississippian (Fig. IOC). It is unknown whether this apparent shallowing was achieved through basin fill, sea level change, or tectonism. However, a general coarsening-upward trend exhibited by the Tk'emlups Formation may imply basin fill (Fig. 5). Conversely, lack of foreslope carbonate debris and a relatively sharp transition between clastic and carbonate facies suggests a more rapid tectonic or eustatic process. A model for carbonate sedimentation in island-arc settings was outlined by Soja (1996) for limestone bearing island-arc terranes in the North
American Cordillera. Sedimentological characteristics of the South Thompson
Formation that coincide with this model include rapid aggradation of carbonates, prevalence of lagoonal deposits, and complex facies relationships between volcanic and carbonate rocks.
The Sandstone and Conglomerate members of the South Thompson
Formation are examples of the above-mentioned complex carbonate - volcaniclastic facies relationships. Each records a rapid relative sea-level fall, reworking of carbonate facies, and progradation of proximal clastic facies, although the former is overlain by carbonates signaling a return to normal marine conditions (upper carbonate unit) and thus is unlikely a product of tectonic uplift
(Fig. 1OD). The Conglomerate Member, typified by heterolithic debris flows
(volcanic-lithic, limestone, and siltstone cobbles), records erosion of both carbonate and volcanic facies in addition to representing the base of a ca. 15 Ma unconformity. This unit is therefore more likely the result of significant tectonic activity (Fig. IOE).
Subsequent to the denudation of the Tk'emlups and South Thompson
Formations, marine transgression provided the re-establishment of carbonate deposition. The relatively pure limestones of the McGregor Creek Formation represent carbonate platform development well away from input of significant clastic detritus. This implies rocks of the Tk'emlups and South Thompson formations were submerged or buried during the Permian (Fig. IOF). CHAPTER 3: TECTONIC HISTORY OF THE QUESNEL TERRANE IN THE AREA OF KAMLOOPS, BRITISH COLUMBIA*
Abstract
Rocks assigned to the Quesnel Terrane are represented by the predominantly island-arc related successions of the Harper Ranch, Nicola, and Rossland groups in the Kamloops area of British Columbia. Unconformities between and within these groups help to establish and constrain the timing of tectonic events in the Quesnel Terrane at this latitude during the late Paleozoic and early
Mesozoic. Refined biostratigraphy and mapping, including the formal and informal recognition of subdivisions of the aforementioned groups, provide a temporal framework for the tectonic evolution of the Quesnel Terrane. The
Harper Ranch Group comprises the Devonian to Mississippian Tk'emlups
Formation, the Late Mississippian South Thompson Formation and the Lower to
Middle Permian McGregor Creek Formation. The Tk'emlups Formation represents deposition of predominantly volcaniclastic strata, the South
Thompson Formation of the Harper Ranch Group records volcanic quiescence and development of arc-flanking carbonates. The McGregor Creek Formation is represented by secondary chert-rich carbonates. The Harper Ranch Group is broadly correlative with similar successions in the Stikine, Chilliwack, and eastern
Klamath terranes. Upper Permian to Middle Triassic rocks are not recognized in the area. The Nicola Group records renewed arc-related magmatism and
2 Formatted using the guidelines for submission to the NATMAP Ancient Pacific Margin synthesis volume 57 sedimentation in the Late Triassic. The Rossland Group, represented by conglomerate, agglomerate and undifferentiated volcanic rocks, represents a third, Early Jurassic island-arc succession. In places rocks of the Rossland
Group unconformably overlie those of the McGregor Creek Formation implying pre-Jurassic uplift and erosion.
Introduction
Northeast of Kamloops, British Columbia, strata included within the
Quesnel Terrane are relatively poorly exposed and formerly mapped only at a reconnaissance scale (Smith, 1979; Monger and McMillan, 1984). Previous studies have demonstrated that these strata may be divided into three assemblages: the upper Paleozoic Harper Ranch Group, the Upper Triassic
Nicola Group, and the Lower Jurassic Rossland Group (Smith, 1979; Danner and
Orchard, 2000; Beatty, 2002). Each assemblage comprises rocks of mainly island arc affinity, separated from the others by unconformities representing tectonic events of unknown duration and intensity. The timing of these events, constrained by new paleontological data, geologic field relationships, and regional correlations summarized here, provide important constraints on the tectonic history of the Quesnel Terrane.
New geologic mapping at a scale of 1:20 000 coupled with sampling for conodont fossils forms the basis for this study which focuses on the following: (1) the stratigraphic succession of rocks in the area assigned to the Harper Ranch, Nicola, and Rossland groups; (2) the timing of tectonic events within the Quesnel Terrane during the late Paleozoic and Mesozoic; and (3) correlating with time- equivalent volcano-sedimentary successions within the southern Canadian Cordillera with emphasis on implications for a shared tectonic evolution. The results provide the basis for both intra- and inter-terrane correlations in the southern Canadian Cordillera and promise to form a temporal framework for the evolution of the Quesnel Terrane. The study area comprises about 700 km2 directly northeast of the city of Kamloops, British Columbia (Fig. 11). The boundaries of the study area broadly follow faults or suspected faults of unknown age except to the north. The area encompasses a large northwest trending block comprising Upper Paleozoic volcaniclastic, siliciclastic, and carbonate strata of the Harper Ranch Group, bounded by or in fault contact with Lower Mesozoic rocks to the south and east. Early Mesozoic and older rocks are at sub-greenschist grade and variably faulted and folded. However, this paper focuses primarily on stratigraphic relationships and the apparently complex structural story is addressed only in a basic manner where it directly affects stratigraphic interpretations.
Regional Geologic Setting
The Quesnel Terrane is the easternmost of the lithotectonic terranes assigned to the Intermontane Belt in the Canadian Cordillera extending from north-central British Columbia to northern central Washington (Fig. 1IA). Paleozoic rocks included in the Quesnel Terrane are polydeformed and were deposited in at least two different tectonic settings: the island-arc related Harper Ranch Subterrane and the oceanic Okanagan Subterrane. These represent the stratigraphic base of the Quesnel Terrane, although the pre-Mesozoic relationships of these assemblages are poorly understood. A complex mix of island-arc assemblages and related igneous intrusions of Late Triassic and Early Jurassic age unconformably overlaps the Paleozoic subterranes giving Figure. 11. (a) Generalized map of the North American Cordillera with reference to terranes discussed in this paper (Quesnellia, Cache Creek, Chilliwack, and the eastern Klamath) as well as the five morphogeologic belts of the Cordillera (Modified from Wheeler and McFeely, 1991). Numbers indicate locations of time stratigraphic columns illustrated on figure 16. (b) Hillshade relief map encompassing the study area northeast of Kamloops, B.C. Eastern Klamath --- integrity to the Quesnel Terrane. In the southern Canadian Cordillera the Nicola and Rossland groups are representative of this Mesozoic magmatic arc complex
(Mortimer, 1987). The upper Paleozoic Harper Ranch Group is the type stratigraphy for the Harper Ranch Subterrane and, in the Kamloops area, represents the stratigraphic base of the Quesnel Terrane. There, rocks of the
Quesnel Terrane are overlain by Tertiary volcanic rocks and unconsolidated
Quaternary sediments (Fig. 12).
East of the study area, across the Louis Creek Fault, rocks of the Eagle
Bay Assemblage, comprising metavolcanic rocks and metasedimentary rocks of the Kootenay Terrane, are structurally juxtaposed with rocks of the Quesnel
Terrane. The Kootenay Terrane represents a Proterozoic to Paleozoic succession that developed on or beside the margin of the North American craton
(Colpron and Price, 1995). North and south of the study area, rocks of the
Quesnel Terrane structurally overlap the western margin of the Slide Mountain
Terrane (Schiariua and Israel 2001 ; Roback, 1993). The Upper Paleozoic Slide
Mountain Terrane comprises chert, basalt, gabbro, and associated rocks of oceanic affinity that may have formed within a back-arc basin and later were thrust eastward onto rocks of the Kootenay Terrane (Ferri, 1997). The basin represented by Slide Mountain rocks records the presence of an ocean of unknown width, separating the Kootenay and Quesnel terranes during the late
Paleozoic. Northeast of the study area, emplacement of Slide Mountain above the Kootenay Terrane has been interpreted as a Permo-Triassic event (Read and
Okulitch, 1977; Ferri, 1997; Schiariua et a/.,2002). Figure 12. (a) Simplified geologic map of the Kamloops area. DHF = Dome Hills
Fault; HLF = Heffley Lake Fault; LCF = Louis Creek Fault; RCF = Robbins Creek
Fault; TRF = Thompson River Fault. Contour interval is 200 m. (b) Legend for
Figure. 12a.
!?I ~ockUnit Svmbol Quaternary r~-i 10 Quaternary: glacio-fluvial/lacust~nesilt; driff fault: unknown displacement KAMLOOPS GROUP \ Eocene - (Miocene?) inferred fault: unknown displacement basalt, minor sandstone, siltstone
"13~-'x. Contour line, elevation in metres, INTRUSIVE ROCKS contour interval 200 m Late Triassic - Early Jurassic @ Key fossil locality, number Mount Fleet Alkaline Complex: mega-cryst corresponds to Table 1 and syenite, quartz monzonite Figure 16.
MafidUItramafic intrusives-granodiorite, diorite, @) Key reworked fossil locality, Bg clinopyrixenite, quartz monzonite, includes Heft7ey Creek number corresponds to Table 1 Pluton and Paul Peak stock and Figure 16. ROSSLAND GROUP Lower Jurassic Lions Head Volcanic member: andesite, volcanic breccia, conglomerate, siltstone, agglomerate NICOLA GROUP Upper Triassic Rayleigh conglomerate - limestone and volcanic lithic conglomerate, minor siltstone, sandstone, pelite Armour Creek Succession- andesite, basaltic andesite, tuft sdtstone, minor pillow basalt Dome Hills Succession- argillite, siltstone, sandstone, andesite, chert, limestone, augite porphyry, tuft pillow basalt HARPER RANCH GROUP
iaicGregor Creek Formation: limestone Upper Mississippian South Thompson Formation: limestone, Mount Harper Pebble Beds: minor volcaniclastic sandstone, conglomerate chert pebble conglomerate, bioclastic sandstone, sandstone, Upper Devonian - Mississippian siltstone TkJemlupsFormation: mudstone, siltstone, volcaniclastic sandstone, tuft conglomerate, chert,
Isotopic studies of Upper Paleozoic rocks of the Slide Mountain and Kootenay terranes (Patchett and Gehrels, 1997) and Upper Triassic rocks of the Quesnel terrane (Untershutz et a/., 2002) indicate both juvenile-arc and evolved cratonic sources of clastic sediment, implying proximity to ancient North America during those times.
West of the study area are volcanic rocks and associated sediments of the west-facing Nicola volcanic-arc (Mortimer, 1987). Further west are limestone, radiolarian bedded chert, argillite, and basic volcanics of the Cache Creek
Terrane. These include Pennsylvanian to Triassic fossil bearing limestones and ribbon chert with fossils of proposed Tethyan affinity as well as an accretionary melange recording subduction west of the Quesnel Terrane during the Late
Triassic (Travers, 1978; Orchard et a/., 2001). Coeval Permian rocks in the
Harper Ranch Group contain distinctly different faunal components to those of the Cache Creek Terrane (Orchard et a/., 2001), suggesting these terranes were separated at this time. Stratigraphic linkages between the Quesnel and Cache
Creek terranes however, have been proposed for Early Jurassic time (Travers,
1978).
Deformation of the Quesnel Terrane at the latitude of the study area is poorly documented, but includes multiple episodes of crustal thickening and possibly one phase of extension, resulting in the structural repetition of the
Harper Ranch and Nicola Group successions. Foliation and axial planar cleavage are predominantly northwest trending and steeply east dipping in sedimentary rocks of the Nicola Group, suggesting the last significant phase of compressive deformation was southwest verging. Deformation between the Late
Triassic and Early Jurassic is likely related to the eastward migration of the axis of Nicola magmatism (Parrish and Monger, 1992).
Stratigraphy
The distribution of the main lithologic units within the study area is shown on Figure 12. Figure 13 presents the composite stratigraphy for the Harper
Ranch Group. Columns 2 and 3 of Figure 16 provide schematic time stratigraphic summaries of the Quesnel Terrane for the west and east parts of the study area.
Map units assigned to the Quesnel Terrane are discussed in the following section. Back pocket figure BP-1 provides detailed unit distribution, station locations, and bedding orientation data at 1:50, 000 scale.
Harper Ranch Group
The upper Paleozoic Harper Ranch Group comprises two distinct successions, one of interpreted island-arc affinity spanning Late Devonian
(Famennian) to Late Mississippian time, and an unconformably overlying
Permian succession interpreted here as a carbonate platform. The lower succession is divided into the volcaniclastic and siliciclastic Tk'emlups Formation and the overlying and locally interfingering South Thompson Formation, the latter comprising limestone and volcaniclastics. The McGregor Creek Formation represents the overlying succession and consists of chert-rich carbonates. Brief descriptions of the major units of the Harper Ranch Group, as well as that of the overlying Nicola and Rossland groups are presented below. Formal descriptions Figure. 13. (a) Composite stratigraphic succession in the area of Kamloops, BC.
(b) General stratigraphic column of the Harper Ranch Group and its component formations in the area of Kamloops, BC. (c) General location of measured sections used to construct the composite section of (b). LEGEND Rock Types
~imestone
n sandstone
-..--. mudstone Symbols --,~~P-UP clasts A A cherty
carbonate aconcretions limestone mudstone ,-g-synsedimentary 'folding sandstonem conglomerate . . -. . ,kiLtrough cross- bedding volcanic rrr major unmnfonity :':':
w bioturbation $ plant fragments @% brachiopods
fusulinids
&& conodonts Sub-Formational Units HMPB Harper Mountain Pebble Beds SM sandstone Member CM conglomerate Member and type sections of the formations comprising the Harper Ranch Group are presented in detail in Beatty, (2003).
Tk'emlups Formation
The Tk'emlups Formation comprises over 2600 m of interbedded mudstone and siltstone, volcaniclastic sandstone and conglomerate. Rocks of the Tk'emlups Formation are distributed throughout the central part of the study area and are in fault contact with the Upper Triassic Nicola Group on both west and east sides (Fig. 12). The Nicola Group also crops out both north and south of the study area, but contacts with the Harper Ranch Group are obscured in these areas by thick glacio-lacustrine deposits in the river valleys. Fault contact with the Nicola Group to the south is likely because the strike of beds of the
Tk'emlups Formation trend into those of the Nicola Group across the South
Thompson River valley without any significant change in elevation. Strata of the
Tk'emlups Formation have been interpreted to be oriented in a steeply east dipping homocline (Smith, 1979). Although way-up indicators and most bedding orientations broadly support this interpretation, mesoscopic folds and apparent structural repetition of units suggests a much greater structural complexity.
Present understanding of the stratigraphic succession of the Harper Ranch
Group implies repetition of the unit and its component formations via folding or large-scale thrust faulting. These features were not observed, but are inferred to occur within the Tk'emlups Formation. Mesoscopic-scale folding and faulting generally increases with proximity to the overlying South Thompson Formation, likely the result of competency differences between the formations. The oldest known rocks in the Tk'emlups formation are the latest
Devonian Harper Mountain Pebble Beds, which crop out along the north side of the main road up Harper Mountain (Fig. 12; Beatty, 2002). The pebble beds, named for distinctive, well-rounded, black chert pebble conglomerate exposed along the length of the outcrop, include sandstone, siltstone, and sandy bioclastic limestone characterized by a latest Famennian shallow-water conodont fauna
(Orchard, 1987). Pebbles in the conglomerate are dominantly radiolarian chert; however, mudstone, andesite, and basalt clasts are also present (Fig. 14A). The pebble beds are overlain by mudstone of Early Tournaisian age assigned to the main part of the Tk'emlups Formation (Beatty, 2002).
The majority of the Tk'emlups Formation is represented by a succession of interstratified volcaniclastic sandstone and mudstone that makes up the greatest portion of the Harper Ranch Group (Fig. 13). This succession consists of two dominant lithologies. The first comprises interbedded mudstone, cherty mudstone, and siltstone (Fig. 14B). These siliciclastic sediments are interrupted by, and interstratified with, medium- to very coarse-grained volcaniclastic sandstone and conglomerate/breccia units (Fig. 14C) representing the second dominant lithology (Smith, 1979; Beatty, 2002).
The coarser-grained units comprise massive to planar-bedded volcaniclastic sandstone that commonly have sharp, erosive bases and are gradational with overlying finer-grained units. The medium-grained sandstone to cobble conglomerate units are composed of, in order of abundance, volcanic lithic clasts, pumice, feldspar crystals, mudstone intraclasts, volcanic quartz Figure 14. Thin section photomicrograph and outcrop photos of select lithologies of the Harper Ranch Group and Rossland groups. (A) Thin section photomicrograph of chert pebble conglomerate representative of the Harper
Mountain Pebble Beds of the Tk'emlups Formation. Cross-polarized light, width of view field = 3 cm. C = chert, note relict radiolaria (arrows); sst = siltstone pebble; matrix comprises coarse quartz-rich sandstone. (B) lnterbedded fine- grained sandstone (fst) and mudstone (mst) of the finer grained facies association of the Tk'emlups Formation. Note load and flame structures in mst
(emphasized by line). Pencil (15 cm) for scale. (C) Typical volcaniclastic debris flow of the Tk'emlups Formation. Note sharp inverse graded base and normal graded top. Grey polygon represents relative grainsize. Cst = coarse-grained sandstone, vcst= very coarse-grained sandstone, pst= pebbly sandstone;
Jacob's staff (top centre) for scale (10 cm divisions). (D) Contact between
Tk'emlups and South Thompson formations. Arrows indicate siltstone interbeds in limestone. Jacob's staff for scale (arrowed). (E) Volcaniclastic sandstone and concretionary mudstone of the Sandstone Member of the South Thompson
Formation. Arrows indicate calcareous concretions in red argillaceous mudstone interpreted as paleosol. Hammer for scale. (F) Limestone of McGregor Creek
Formation. Arrows indicate chert interbeds. Outcrop width approximately 30 m.
(G) Fault-related folding of McGregor Creek Formation west of Lafarge quarry.
Outcrop height approximately 7 m. (H) Basal heterolithic conglomerate of Lions
Head Volcanics northeast of Lafarge Quarry. Large cobbles of latest Triassic limestone (Ist), chert pebble conglomerate (cgl), sandstone, and volcanic rocks with red volcaniclastic sandstone matrix. Hammer for scale. crystals, and various amounts of calcareous allochems. The dominant lithologies of the volcanic lithic clasts are aphanitic andesite, feldspar-phyric andesite, feldspar-quartz porphyry, and volcanic chert, together suggestive of an intermediate volcanic source. Commonly observed sedimentary features include sharp, scoured, and inverse graded bases (Fig. 14b), normally graded tops, upward shift from closed to open framework, and density grading resulting in concentrations of pumice clasts near the tops. Individual units are metre-scale thickness, but commonly form massive and amalgamated units ranging from five to seven metres total thickness.
Rare plant debris (filopsids?) present in the Tk'emlups Formation suggests the presence of a vegetated hinterland throughout its depositional history.
Although fossil evidence is rare from the Tk'emlups Formation, conodont collections made from the base, and from the overlying and interfingering South
Thompson Formation constrain its age range to Late Devonian to Late
Mississippian (Orchard, 1987; Beatty, 2002; this study). No major breaks in sedimentation are apparent and persistent sedimentation likely occurred throughout this time.
Interpretation
The Harper Mountain Pebble Beds represent the some of oldest rocks of the Harper Ranch Group and infer a pre-Late Famennian history for the
Tk'emlups Formation. This history has been confirmed by the recovery of Early
Famennian conodonts from a limestone clast within conglomerate from the
Tk'emlups Formation (F3, Fig. 12; Sample 01-OF-B-124, Appendix D). Uplift and erosion of deep water strata, providing the source for the pebble beds, may have been accomplished through thermal doming of the crust during the early history of the nascent arc complex (Larue et a/., 1991). The juxtaposition of an outer shelf fauna of lower Tournaisian conodonts within a deep-water clastic succession overlying the pebble beds indicates a relative rise in sea level
(Beatty, 2002). This is coincident with a global transgression at the Devonian -
Carboniferous boundary (Mawson and Talent, 1997). Construction of the arc complex continued throughout the Mississippian as recorded by the thick accumulation of volcaniclastic and siliciclastic sediments. Initial accommodation space therefore was maintained via basin subsidence throughout much of the
Mississippian.
Mudstone and siltstone associations have been interpreted as hemipelagic and distal turbidite deposits respectively (formed by low-density turbidity currents sensu Lowe, 1982) and represent, for the most part, background (ambient) sedimentation in the basin (first suggested by Smith, 1979;
Beatty, 2002). Soft sediment deformation is common, typical of turbidite emplacement and down slope movement (Fig. 14C). Tectonic and volcano- seismic instabilities may also have affected early deformation (Smith, 1979).
Volcaniclastic sandstone and conglomerate units represent sediment gravity flows, which periodically interrupted ambient sedimentation. These likely resulted from sediment oversupply and destabilization in proximal environments
(Sigurdson et a/., 1980; Bull and Cas, 1991). Sedimentological characteristics of sandstone - conglomerate units
support interpretation as sediment gravity flows. Features such as layered
traction carpets, inverse and normal grading, and entrained rip-up clasts support
designation as both debris flows (debrites) and turbidity flows (turbidites) (high-
density turbidity currents sensu Lowe, 1982) suggesting that many of the flows were transitional between these two transport mechanisms. Flow variation was
likely due to basin topography and fluctuating sediment supply from pulsing
eruptions. Clay content, now immeasurable due to alteration, may have been a
significant factor in suppressing turbid flow (Marr, 1999). Flow transformations at the head of the coarse-grained debriteslturbidites, resulting in the formation of
dilute subsidiary turbidity currents, may be responsible for the deposition of the
overlying distal turbidites (Fisher, 1983). However, the great volume of finer- grained rocks attributable to distal turbidites implies initiation from more than just the aforementioned process and may be due to slope failure, sediment over- supply, or storm activity.
Lithologic characteristics of Tk'emlups volcaniclastic sandstone units suggest division into two end members of contrasting provenance. An epiclastic-
rich end member is characterized by the dominance of volcanic lithic clasts admixed with mudstone and carbonate grains. Components of epiclastic-rich deposits are interpreted to have resided in proximal environments such as arc- flanking deltas prior to redistribution into the basin. During this residence time, sandstones were winnowed and fines were likely transported basinward, size sorting however was likely obliterated during transport as debris flows. Epiclastic-rich debris flows, the result of destabilization of the proximal environment are likely due to sea-level fluctuation or seismic activity (Bull and
Cas, 1991).
The pyroclastic-rich end member is characteristically rich in pumice and angular and shattered feldspar and quartz crystal fragments. These grains are interpreted to have spent minimal residence time in proximal environments. This end member was transported to deep-water environments via pyroclastic debris flows breaching the air-water interface; and must be essentially syn-eruptive.
Pyroclastic-rich units are more common in the upper part of the Tk'emlups
Formation, this may be due to either a reduction in accommodation space associated with basin filling, or increase in the volume of eruptions and consequently pyroclastic supply. The former explanation is preferred, as the presence of the conformably overlying, carbonate dominated, South Thompson
Formation requires a reduction in clastic input and positioning within the photic zone. Recognition of, and discrimination between, these two lithologies of debris flows may provide a proxy for volcanic activity within the adjacent volcanic centre. Furthermore, the apparent up-section trend of increasing pyroclastic debris may aid in future subdivision of the Tk'emlups Formation.
South Thompson Formation
Overlying and rarely interfingering with the Tk'emlups Formation is the
Upper Mississippian South Thompson Formation (Fig. 13, 14D). The South
Thompson Formation crops out as several generally northwest trending limestone bodies occurring throughout the belt occupied by the Tk'emlups Formation (Fig.12). General bedding attitudes in most outcrops are, like the
Tk'emlups Formation, predominantly northwest striking and steeply east dipping.
In the area of the proposed type section, (South Thompson #2 locality of Sada and Danner, 1974; Beatty, 2003) the South Thompson Formation has a measured thickness of 272 metres. Throughout the study area, the thickness of the South Thompson Formation varies from about 150 to 300 m in most parts of the study area, but is greater than 350 m thick on Harper Mountain (Fig. 12).
The South Thompson Formation comprises a succession of limestone that is variably fossiliferous and contains volcaniclastic and tuffaceous sandstone, and mudstone interbeds. Where observed, contacts with the Tk'emlups
Formation are sharp or gradational over short intervals. The majority of basal carbonate facies record bioclastic limestone deposition, comprising massive to bedded packstone and wackestone, however locally this is preceded by spicular lime-mudstone. Succeeding brachiopod and fusulinid packstone facies record overall progradation of the carbonate sequence. Allochems, largely consisting of pelmetazoan, brachiopod, and fusulinacean hash, are broken, abraded, and variably micritized. Algal-generated micritization implies a period of residence within the photic zone prior to subsequent remobilization.
Fossils recovered from the South Thompson Formation include ammonoids, brachiopods, bryozoans, conodonts, corals, fusulinaceans, gastropods, and characteristic (Dawson, 1879; Danner et a/., 1999) unusually large crinoid columnals typically 15-30 mm diametre. Initial studies of this unit focused on fusulinid collections (Sada and Danner, 1974; 1976). Age determinations based on fusulinids ranged from Early to Late Pennsylvanian
(Skinner and Wilde, 1966; Sada and Danner, 1974, 1976; Smith, 1979), although determinations made from brachiopods were Late Mississippian (Dutro in Smith,
1979). Subsequent studies focusing on conodonts recovered from the South
Thompson Formation have consistently provided Late Mississippian (late Visean
- early Serpukhovian) ages (Orchard, 1987; Orchard, 1991). Conodont collections for this study confirm these results.
At several localities of the South Thompson Formation, including the proposed type section, an upper and lower carbonate succession is recognized on the basis of an intervening clastic unit. Correlations between several exposures of the South Thompson Formation suggest that this break in carbonate deposition was due to a regional event, probably relative sea level fall, rather than localized uplift. The intervening volcaniclastic sandstone unit, ranging from 0 to >60 m thick, is referred to as the Sandstone Member of the South
Thompson Formation (Fig. 13). The Sandstone Member comprises massive fine- to medium-grained volcaniclastic sandstone overlain by a paleosol (Fig.
14E). The fossil content of the overlying upper carbonate unit however is identical to that of the lower carbonate and thus does not indicate a significant unconformity.
In a single exposure along the north side of the South Thompson River a
62 m thick succession of limestone-cobble conglomerate and volcaniclastic sandstone and conglomerate overlies the upper carbonate unit of the South
Thompson Formation. This unit is referred to as the Conglomerate Member of the South Thompson Formation (Fig. 13). Metre scale conglomerate beds, interpreted as debris flows, characterize this member. The debris flows are interbedded with purple and green coloured sandstone and siltstone suggestive of alternating oxidizing and reducing conditions (Johnson et al., 1997). Rare carbonaceous material, apparent on bedding surfaces, further suggests proximity to terrestrial sources. Although not directly dated, the Conglomerate Member is latest Mississippian, or possibly, Pennsylvanian in age and represents the youngest preserved strata beneath the sub-permian unconformity (Fig. 13).
Interpretation
The South Thompson Formation records an abrupt change from volcaniclastic to carbonate deposition. This suggests a rapid shift to carbonate producing environments, specifically low turbidity, most likely resulting from volcanic quiescence (Beatty, 2002) and the depletion of shallow marinelsubaerial volcaniclastic reservoirs. Two shoaling upward sequences are recognized, comprising open marine, mostly middle shelf, carbonates each capped with marginal marine to terrestrial clastics. The Sandstone Member is interpreted to represent the progradation of foreshore - coastal plain environments over the middle shelf, thus indicating a fall in relative sea level. Algal laminated lime- mudstone in the upper part of the lower carbonate unit supports this interpretation. The upper carbonate to Conglomerate Member succession is poorly understood, however, the polymict conglomerate debris flows imply a heterolithic source and thus exposure and erosion of both the Tk'emlups and
South Thompson formations. Collections made from both the base and the top of the South Thompson
Formation produced nearly identical conodont and fusulinid faunas, suggesting relatively rapid carbonate deposition. This is consistent with Soja's (1996) model for the development of fringing reefs flanking island-arcs, where subsidence related to the cooling of the arc edifice drives the rapid aggradation of carbonate facies. In this model, magmatism ceases or slows as the volcanic-arc matures, allowing for the formation of fringing reefs that evolve into atolls and are finally drowned due to subsidence of the cooling volcanic-arc. The Sandstone and
Conglomerate members of the South Thompson Formation are notable deviations from this model, and suggest tectonically influenced uplift and subsidence patterns for the Harper Ranch Group during this time of deposition.
McGregor Creek Formation
Rocks of the McGregor Creek Formation are preserved as prominent hills in the south-central part of the study area as well as thin, isolated, and probably fault bounded packages enclosed by the Nicola Group succession (Fig. 12; Fig.
BP-1). The Canada Lafarge Cement Company has produced notable exposures of this unit in a large quarry north of the South Thompson River. The unit is of economic importance because it is composed mostly of pure limestone, although secondary chert beds (Fig. 14F) and rarely, argillaceous limestone beds are also present. Compositional variations in the McGregor Creek Formation illustrate the structural complexity of the unit by outlining folds within the quarry (Fig. 14G).
Conodont studies have further emphasized this complexity by defining structural repetition of McGregor Creek Formation faunal subdivisions within the quarry
(Orchard and Forster, 1988).
The stratigraphic base of the McGregor Creek Formation is not exposed but can be located to within several metres west of the Canada Lafarge Quarry.
However, Danner (1976; Danner et al., 1999, p. I10) suggests that this unit is paraconformable with the South Thompson Formation in the Dome Hills area.
Although neither the base nor top of this succession is apparent in the study area, measurements west of the Lafarge Quarry indicate a minimum thickness of
512 m (Fig. 13; Beatty, 2003).
The McGregor Creek Formation comprises massive to bedded wackestone and packstone with an age spanning the Early to Middle Permian
(Orchard and Forster, 1988; Danner et al., 1999). The carbonates of this unit are characteristically chert rich and are marked with common chert nodules and metre scale, secondary chert beds (Beatty, 2003). Fossils are common, and corals, brachiopods, and fusulinids are locally abundant in outcrop. Most exposures of the McGregor Creek Formation appear deeply weathered, developing a sugary crust in places 10's of cm deep.
Interpretation
The McGregor Creek Formation represents deposition in an open marine environment on a stable, slowly subsiding carbonate platform. Deposition of the unit took place over ca. 36 Ma as indicated by conodont biostratigraphy (Orchard and Forster, 1988) and during this time carbonate facies did not vary significantly from what can be assigned to the middle shelf environment (Wilson and Jordan, 1983). No evidence for major relative sea level fluctuations or syndepositional tectonic events is present.
Several workers have included the Harper Ranch Group within a
Cordilleran belt of Upper Paleozoic rocks of island arc affinity based on the faunal components of the McGregor Creek Formation. This has come to be known as the "McCloud belt" (Miller and Wright, 1987), named for the Lower
Permian McCloud Limestone of the eastern Klamath Terrane (Fig. 1 IA). The
McCloud Limestone and members of the McCloud belt are unique in the
Cordillera because they posses faunal elements of mixed North American and apparently exotic affinity. This mixed faunal signature is the basis for proposed longitudinal separation of terranes belonging to the McCloud belt from North
America during the Upper Paleozoic (Stevens and Rycerski, 1983; Belasky and
Runnegar, 1994, Belasky et a/., 2002). Most recent estimates of the separation of the McCloud belt from the west coast of North America have been reported as
2000 - 3000 km (Belasky et a/., 2002).
Nicola Group
The Nicola Group is an assemblage of mainly Upper Triassic basaltic andesite and andesite flows interstratified with related volcaniclastic sediments, mudstone, and limestone (Mortimer, 1987; Schau, 1970). These rocks are commonly associated with calc-alkaline to alkaline coeval and younger intrusions
(Mortimer, 1987). Rocks in the study area assigned to the Nicola Group crop out both west of the Dome Hills fault and east of the Heffley Lake fault thus flanking rocks of the Harper Ranch Group (Fig. 12, 15). In the Dome Hills area, strata of 78 the Nicola Group remained undifferentiated from upper Paleozoic strata until recognized as being of Late Triassic age, based on fossils recovered from interbedded limestone (Campbell, in Smith, 1979). Southeast of Heffley Lake, in the area of Shaw Hill, deformed volcanic flows, siltstone, and tuff (map unit uTrNv Fig.l2), were previously included in Dawson's (1896) lower Paleozoic
Niskonlith series and later included in Monger and McMillanls (1984) undifferentiated Devonian to Triassic map unit (Unit DTu). Paucity of fossils and lithologic similarity to the Tk'emlups Formation of the Harper Ranch Group are likely factors in the late recognition of the Upper Triassic age of strata in this area.
The Nicola Group is subdivided here into three informal map units (Fig.
12). The westernmost unit, the Dome Hills succession, comprises mostly sedimentary rocks of Carnian and Norian age and hosts the Paul Peak stock.
The Armour Creek succession comprises the eastern outcrop belt of Nicola
Group rocks in the study area and is characterized by mostly volcanic rocks, dominated by andesite, pillowed augite-phyric basalt, and tuffaceous sandstone.
The undated Armour Creek succession is both lithologically distinct and geographically separated from the Dome Hills succession and their stratigraphic relationship remains uncertain. The third unit, the Rayleigh Conglomerate, is also undated but consistently associated with limestone of the McGregor Creek
Formation (Fig. 12). It may represent the stratigraphic base of the Nicola Group, a syndeformational unit, or possibly two distinct successions in the western and Figure. 15. Schematic cross-sections showing the relationship of Nicola Group strata to Harper Ranch Group strata. (A) Juxtaposition via the Heffley Lake and Dome Hills normal faults. (B) The Dome Hills fault as a thrust fault. McGregor Creek Formation limestone in the Dome Hills area represents a slump block , klippe(?), or a structurally interleaved (depicted here) portion
Dome Hills -*i it South Thompson River -H+ Shaw Hill eastern parts of the study area. Figure 15 illustrates the relationships of the
Armour Creek succession to the east and the Dome Hills succession to the west, with rocks of the Harper Ranch Group exposed in the central part of the study area. Two possible mechanisms to explain the formation and distribution of the
Rayleigh Conglomerate are illustrated.
Dome Hills Succession (Unit uTrNs)
Sedimentary and locally volcanic rocks of the Dome Hills succession crop out in the southwest part of the map area along the ridge occupied by Peter Peak and extend northwest across the Paul Creek valley in the Dome Hills (Fig. 12).
These rocks are bounded to the east by a northwest-trending fault, referred to here as the Dome Hills fault, and to the south and west are covered by unconsolidated Quaternary sediments. Previous workers included this succession in the eastern sedimentary belt of Preto's (1979) tripartite subdivision of the Nicola Group (Smith, 1979; Monger and McMillan, 1984).
The succession is apparently folded into a syncline-anticline pair with axial traces that trend roughly northwest (Smith, 1979). The S1 cleavage foliation trends northwestward where observed and is moderately to steeply east dipping
(Beatty, 2003). Smith (1979), in a detailed study of this succession, divided it into five map units based on lithologic trends and estimated their total thickness to be at least 3000 m. Revision of biostratigraphic data from the Dome Hills succession (M.J. Orchard, pers. comm., 2002) suggest an apparent younging eastward, rather then westward as in Smith's (1979) interpretation. Rocks of the Dome Hills succession consist mainly of laminated mudstone, siltstone, chert, volcaniclastic sandstone and mafic volcanic flows.
Minor lithologic components include massive and redeposited (turbiditic?) limestone, red and green argillite, intraformational conglomerate and locally pillowed basalt. Mudstone and interbedded mudstone and siltstone units are generally poorly to moderately bioturbated. Traces consist of simple horizontal to sub-horizontal burrows, typically Planolites and rare Helminthopsis.
Volcaniclastic sandstone units, like those of the Tk'emlups Formation, comprise both pyroclastic and epiclastic gravity flows that range from fine- grained sandstone to pebble conglomerate. In the field, these units are indistinguishable from similar lithologies in the Harper Ranch Group. Volcanic flows include andesitic to basaltic units displaying porphyritic, amygdoidal, and pillowed textures. Rare interstitial limestone is present in pillowed units.
Massive micritic and bioclastic limestone crops out in the northwestern part of the Dome Hills. Fossil collections (sample 01-OF-B-162a, Appendix D) from these outcrops indicate late Carnian to early Norian ages; collections from turbiditic limestone in the southern part of the Dome Hills (sample 01-OF-B-109,
Appendix D) and interpillow limestone on Peter Peak Ridge (sample OI-OF-B-
85b, Appendix D) are of Carnian age. Thus the Dome Hills succession is at least in part of Carnian to early Norian age, although the paucity of datable horizons does not preclude a longer range for the succession. Interpretation
The Dome Hills Succession represents distal sedimentation in an island- arc environment similar to that of the Tk'emlups Formation of the Harper Ranch
Group. Notable differences with the Tk'emlups Formation are the presence of volcanic flows and rare limestone interbeds, some of which form massive linear bodies (backpocket Fig. BP-1). These differences imply the Dome Hills
Succession to be relatively more proximal than the Tk'emlups Formation, although comparable overall thickness suggests similar subsidence patterns.
The presence of pillowed basalt and thin augite porphyry flows indicate coeval volcanism and may suggest the presence of multiple vents. The Paul Peak stock
(discussed below) is geographically associated with much of the recognized pillow basalt on Peter Peak Ridge (Fig. 12) and may represent a feeder chamber for the Late Triassic volcanics.
Armour Creek Succession (uTrNvs)
The Armour Creek succession comprises mafic volcanic rocks and associated sediments that crop out in the northeastern part of the study area.
The stratigraphic base of this succession is uncertain, however, it appears to be overlain by and possibly in part coeval with conglomerate of Unit uTrNc (Fig. 12).
Bed orientation data is sparse, but generally indicate steeply dipping, northwest trending orientations. Thickness of this unit has yet to be determined, however map relationships suggest a thickness of at least 1200 m. Rocks in the eastern part of this succession are sub-greenschist grade much like those of the Harper
Ranch and Nicola groups to the west. Massive augite-phyric basaltic flows and redeposited crystal lithic tuff constitutes the most volumetrically significant proportion of this succession.
Locally, pillowed augite-phyric basalt is present and interstitial limestone was observed at one outcrop. This limestone was sampled for microfossils, but was barren (sample 01-OF-B-305, Appendix D). Sedimentary rocks constitute a minor proportion of the Armour Creek succession, comprising siltstone, fine- grained sandstone, minor mudstone, and the aforementioned limestone.
North of Heffley Lake, Carnian age sediments (Orchard, in Friedman et a/., 2002) including massive limestone are intruded by dykes related to the
Heffley Creek Pluton. These sediments are correlated with the Dome Hills succession on both biostratigraphic and lithologic grounds. Based on intrusive relationships as well as general bedding orientations it is believed that the
Armour Creek succession stratigraphically overlies rocks correlated with the
Dome Hills succession and is therefore at least in part younger. North of the study area, in the Bonaparte Lake map sheet, Schiariua et a/. (2002) divided rocks of the Nicola Group into three generally north-south trending belts. The central belt, comprising volcanic and mixed sedimentary and volcanic rocks, is reported to stratigraphically overlie Anisian to Carnian (Orchard, in Schiarizza et a/. 2002), mainly sedimentary rocks of the eastern and western belts. Thus, stratigraphic relationships in both areas suggest that the Nicola Group experienced a renewed pulse of volcanism in Carnian, or more likely post
Carnian, time. Interpretation
The Armour Creek Succession, although lithologically similar to rocks of the Nicola Group, and in the area, associated with rocks correlated with the
Nicola Group, remains undated and may represent a correlative of the Lower
Jurassic Lions Head Volcanics (discussed below), or an as yet unrecognized unit. Reconnaissance east of the study area revealed the presence of potentially correlative volcanics approximately 2 km east of Louis Creek along the road to
Todd Mountain. If assigned to the Nicola Group, the rocks of the Armour Creek
Succession correlate on lithologic grounds with the western volcanic belt of Preto
(1979), although they crop out much farther east than most of this belt. Cleavage was observed in these rocks in proximity to, and generally parallel with the Louis
Creek Fault. If correlative with the Lions Head Volcanics continuity of these rocks across the Louis Creek Fault implies there is little offset on this structure.
Rayleigh Conglomerate (uTrNc)
The Rayleigh conglomerate comprises limestone, lithic, and volcanic pebble to boulder conglomerate with a variable matrix of volcaniclastic sandstone, siltstone and calcareous siltstone. The conglomerate is exposed in both the Dome Hills and Shaw Hill areas (Fig. 12) and may represent two originally, geographically distinct successions. Both successions of the Rayleigh conglomerate crop out in proximity to observed or inferred faults and may be related to these features (Fig. 15). The thickness of this unit is both locally and regionally variable. In the Dome Hills area the unit ranges in thickness from less than five metres to an estimated thickness greater than 100 m. In the Shaw Hill area, unit thickness is apparently more uniform and is estimated at greater than
500 m.
In the Dome Hills area, the Rayleigh conglomerate unconformably overlies
Lower Permian limestone of the McGregor Creek Formation with a recognizable karsted contact (Beatty, 2002). In places volcaniclastic sandstone and limestone pebble conglomerate can be seen to fill fissures as deep as 50 cm in the underlying limestone. The contact may be an angular unconformity (i.e.
Read and Okulitch, 1977) although bedding discordance between the conglomerate and underlying limestone was not observed. Near the contact, conglomerate comprises rounded to subangular limestone cobbles and boulders supported in a pebbly volcaniclastic sandstone matrix, and was likely deposited via debris flows. Limestone cobble content and size decreases upsection and conglomerate grades into voicaniclastic sandstone.
Minor lithologic constituents include pebbles and cobbles of mudstone, siltstone, and volcaniclastic sandstone. The source of these clasts is unknown, but is likely from either the Harper Ranch or Nicola groups. A distinct lithologic variation of the conglomerate crops out locally in the Dome Hills. It comprises elongate and partially deformed limestone and sandy limestone cobbles supported in a fine-grained, red sandstone and red argillite matrix. The source of the limestone cobbles for this portion of the conglomerate is unknown. However, the cobbles appear to be syndepositional to conglomerate as elongate cobbles are commonly bent. This suggests a contemporaneous carbonate source for this localized conglomerate rather than the aforementioned Permian source. Southeast of Heffley Lake, a thick succession of Rayleigh Conglomerate is exposed from Andy Lake to east of Hyas Lake (Fig. 12). Compositionally similar to conglomerate in the Dome Hills, it comprises limestone boulder and cobble conglomerate with volcaniclastic sandstone matrix that locally grades into calcareous siltstone and, in easternmost exposures, phyllite. The contact with underlying Permian rocks of the McGregor Creek Formation is exposed in several locations, but is best seen southeast of Andy Lake (Fig. 12). In this area scattered outcrops of peperite and limestone breccia supported in basalt matrix suggest volcanism was contemporaneous with conglomerate deposition. The
McGregor Creek Formation below the contacts at both Shaw Hill and southeast of Andy Lake is foliated; foliation in both areas is northwest trending and moderately to steeply east dipping. Similar foliation is developed in the matrix of the conglomerate in the Shaw Hill area. Limestone clast content decreases with distance from the underlying Permian source and several exposures are devoid of carbonate ciasts. In these exposures, volcanic boulder conglomerate is interbedded with rare volcaniclastic sandstone beds.
Friedman et a/. (2002) illustrate another outcrop of presumably Permian limestone situated approximately one kilometre west of the north end of Hyas
Lake (Fig. 12). If each of the exposures of McGregor Creek Formation are taken as the base of the Rayleigh conglomerate, three repetitions of the unit can be delineated: (1) east of Heffley Lake fault, (2) east of Armour Creek Fault and, (3) east of an unnamed fault near Hyas Lake. It is uncertain whether this succession has been repeated by thrust faulting, folding, or, whether they represent individual half graben basins developed along normal faults, possibly synthetic to the inferred Heffley Lake fault (Fig. 15A).
Interpretation
The Rayleigh conglomerate has previously been interpreted as the base of the Nicola Group in the area (Beatty, 2002). Map relationships and the overall thickness of the unit in the Shaw Hill area cast doubt on this interpretation.
Interpretation as a fault scarp deposit is possible, as this depositional environment provides the accommodation space necessary to develop conglomerates of comparable thickness to that in the Shaw Hill area. The interpretation that the Rayleigh Conglomerate is stratigraphically high in the
Nicola Group succession can be made by map relationships between the conglomerate and sediments of the Nicola Group cropping out north of Heffley
Lake (backpocket Fig BP-1). Bedding attitudes of limestones (Friedman et a/.,
2002) and sandstones appear to project from north of Heffley Lake southward, suggesting these rocks underlie the Rayleigh Conglomerate, although the two successions are separated by the Heffley Creek Pluton.
Repetition of the Rayleigh Conglomerate in the Shaw Hill area is supported by the presence of three separate bodies of Permian limestone of the
McGregor Creek Formation. In each succession, limestone clast content decreases upsection (eastward) suggesting progressive burial of the underlying limestone source. Thus if the conglomerate represents a single sheet subsequently repeated by thrusting it was originally widespread and thick.
Alternatively, if the conglomerate developed during normal faulting, each succession could represent a distinct fault scarp deposit (Fig. 15A). In the Dome
Hills area, the appearance of the Rayleigh Conglomerate is similar, although
there the underlying McGregor Creek Formation is karsted but not foliated. In
this area, three explanations for its depositional environment are possible. The
first possibility is that parts of the McGregor Creek Formation were down dropped
along normal faults associated with normal offset on the Dome Hills Fault. Here,
as in the Shaw Hill area, the conglomerate would represent a fault scarp deposit
in a half-graben basin. In this case, the distinct lithologic variant characterized by
the red mudstone matrix records later stage basin fill and is broadly coeval with the main portion of the conglomerate, all of which sits high in the Nicola Group
stratigraphy. The second option is that normal movement along the Dome Hills
Fault downdropped the basal Nicola Group conglomerate and a synthetic fault west of this downdropped the upper Nicola Group succession (Dome Hills
Succession). The third possibility is that reverse motion on the Dome Hills Fault emplaced Harper Ranch Group units over the Nicola Group (Fig. 15B). In this
case, the Rayleigh Conglomerate represents a basal Nicola Group conglomerate
interleaved with or sitting on the Dome Hills succession as a klippe. In the two
latter cases, the lithologic variant of the conglomerate, characterized by red
mudstone matrix, represents a syndeformational unit, which postdates much of the Nicola Group.
In both the Dome Hills and Shaw Hill areas, conodonts of Early Permian age have been recovered from limestone clasts in the Rayleigh Conglomerate
(F7, Fig. 12). This suggests that the upper part of the McGregor Creek Formation had been removed prior to conglomerate deposition. The central part of the study area was, at least locally, not as deeply eroded because Middle Permian limestone is preserved here (Nelson and Nelson, 1985). Clasts from the red matrix conglomerate were not dated, however they are lithologically similar to those of latest Triassic age (F8, Fig. 12) in the basal conglomerate of the Lions
Head Volcanics (discussed below). Locally, trough cross-bedded, red sandstone, and rare alternating red to green nodular argillite, all suggestive of proximal shallow or terrestrial environments (Johnson et a/., 1997), occurs within the lithologic variant. Further study is presently underway to attempt to define the age of this potential subdivision of the Rayleigh Conglomerate.
Lions Head Volcanics of the Rossland Group
The Lower Jurassic Rossland Group in its type area in southeastern
British Columbia comprises volcanic and epiclastic rocks and conglomerate unconformably overlying the Upper Paleozoic Mount Roberts Formation across a
Late Triassic paleosurface (Roback, 1993). The age of the Rossland Group is bracketed by Sinemurian dates from fossils and zircons in the Archibald and
Elise formations (Hoy et a/., 1995) and Toarcian fossils in the Hall Formation
(Tipper, 1984).
In the Kamloops area, siltstone, conglomerate, and intermediate volcanic strata unconformably overlying limestone of the Harper Ranch Group are informally named the Lions Head Volcanics and correlated with the Rossland
Group. East of the Lafarge Quarry (Fig. 12) Sinemurian ammonites and bivalves have been collected from a thin fossiliferous siltstone unit at the base of the succession (Beatty, 2002). Bivalves, gastropods, and rare woody debris also occur within this unit. Based on age and lithology, the Lions Head Volcanics are correlated with the Archibald and Elise formations of the Rossland Group.
Previously, this succession was assigned to the Nicola Group (Danner, 1995), and has been interpreted as an example of the basal Nicola unconformity (Daly,
1915; Read and Okulitch, 1977; Orchard and Danner, 2000).
Along the trace of the unconformity following the gully east of the Lafarge
Quarry (Fig. 12) the basal conglomerate cuts deeper stratigraphy northward and may be separated into two lithologically distinct units. The lowermost unit, cropping out immediately east and again approximately 1 km southeast of
Robbins Lake (Fig. 12), comprises chert, limestone, and rare volcanic pebble conglomerate in a carbonate matrix (Unit PJc of Beatty, 2002) and has been observed to overlie limestone of both the South Thompson and McGregor Creek formations. The upper unit is heterolithic, comprising cobbles of sandstone, limestone, and porphyritic volcanics in a distinctive red brown volcaniclastic sand matrix. Limestone cobbles are mostly sourced from the McGregor Creek
Formation, based on fusulinids recognized in hand sample. However, a single pink-coloured limestone clast produced a latest Norian - Rhaetian age conodont fauna (F8, Fig. 12), the youngest recorded from the Nicola Group. Near the base of the upper unit, angular cobble- and boulder- sized clasts of the lower unit are prevalent (Fig. 14G) implying that the lower unit was lithified and eroded prior to the deposition of the upper unit. The red brown matrix of the upper conglomerate unit is similar to that reported from conglomerate of the Archibald Formation in the type area (Hoy et a/., 1995), and has been interpreted as evidence of oxidization.
Overlying the conglomerate units are intermediate volcanics displaying flow, auto-breccia, and agglomerate textures intercalated with minor siltstone and tuff. The total thickness and extent of the Lions Head Volcanics was not determined during the course of this study. However, an apparent thickness of about 5250 m may be calculated from the map relationships (Fig. 12).
Interpretation
This study represents the first firm evidence for correlating rocks in the
Kamloops area with the Rossland Group. However, this succession was not the focus of the study and thus remains poorly understood. Most observations were made near the base of the succession, although eastward the succession was mapped at reconnaissance scale.
The lithologic succession at the base of the unit suggests a marine transgression following uplift and removal of Triassic strata. Chert pebble conglomerate (Fig. 14G) is likely related to wave revinement, representing the reworking of the chert-rich McGregor Creek Formation. Cobble conglomerate, comprising well-rounded cobbles of limestone, sandstone, and intermediate volcanic rocks overlies fossiliferous siltstone, recording the progradation of proximal volcanic facies. Latest Triassic limestone cobbles (sample 01-0F-B-
228 Appendix D) contained in the conglomerate imply erosion of Nicola Group strata occurred in two separate pulses, the first of which was largely complete prior to the latest Triassic and the second occurring during the earliest Jurassic as Nicola Group lithologies are unrepresented in the conglomerate. It is unknown why Jurassic units cut so deeply into the stratigraphy in this area, although this may be the result of topography developed during latest Triassic deformation.
Agglomerate, volcanic breccia, and siltstone comprise the most voluminous part of the Lions Head Volcanics. However, these strata have only a lower age limit of early Sinemurian from the fossiliferous siltstone and the duration of volcanism is unknown. The Pliensbachian age Mount Fleet Alkaline
Complex (discussed below) may be related to these volcanic rocks, broadly providing an upper limit for their duration.
Intrusive Rocks
Three intrusive phases have been recognized in the study area. The largest and oldest of these is the Upper Triassic Heffley Creek Pluton; an
Alaskan-type mafic - ultramafic body intruding rocks of the Nicola Group in the northeast portion of the study area (Fig. 12; Ray and Webster, 2000; Friedman et a/., 2002). The Paul Peak stock, a similar but undated Alaskan-type body, intrudes Nicola Group strata in the southwest part of the study area (Smith,
1979). The next volumetrically significant unit is the Lower Jurassic Mount Fleet
Alkaline Complex, comprising mostly syenitic granite expressed as several subcircular bodies cropping out from the north side of Paul Lake to the north flank of Mt. Lolo (Fig.12). A third intrusive phase comprising lamprophyric dykes and sills is rarely exposed and of unknown age or affinity. Heffley Creek Pluton
The Heffley Creek Pluton comprises pyroxenites, hornblendites, gabbro, diorite, and quartz diorite interpreted as a zoned Alaskan-type mafic - ultramafic body (Ray and Webster, 2000). The pluton crops out, trending southwest, from
Heffley Lake to Shaw Hill centred on the trace of the Armour Creek fault (Fig.
12). Skarn associated with dyke and sill swarms related to the pluton is developed in Late Triassic limestone of the Nicola Group directly north of Heffley
Lake. The dyke swarm is associated with and follows southeast trending fractures that parallel axial planes of folds and S1 foliation developed in the
Nicola Group (Friedman et a/., 2002). Fractures as well as dykes show some folding, implying that they are syndeformational (ibid). Folding and foliation developed in the main body of the pluton provide additional evidence for syndeformational emplacement. Recent UIPb from zircon studies provide a crystallization age of 208+/- 6.1 Ma, placing the time of crystallization in the
Rhaetian (time scale of Okulitch, 1999). The zircons show no sign of crustal inheritance (Friedman et a/., 2002).
Paul Peak Stock
The Paul Peak stock intrudes Carnian age volcaniclastic strata of the
Nicola Group in an elongate northwest trending body on the west side of Peter
Peak Ridge (Fig. 12). Smith (1979) mapped this concentrically zoned pluton as a core of olivine clinopyroxenite surrounded by leucogabbro, diorite, hornblende quartz monzodiorite and hornblende granite. Texture, modal variation, and apparently gradational contacts suggest a differentiation series formed by fractional crystallization (ibid). Although the Paul Peak Stock has not been radiometrically dated, lithologic similarities, syneruptive deformation, and stratigraphic position suggest strong ties with the Heffley Lake Pluton and it is here considered coeval.
Interpretation
Smith (1979), attempting to explain the zonation and level of emplacement of the Paul Peak Stock, suggested the possibility of upward diapiric mobilization of stratiform cumulates of a Nicola arc magma chamber facilitated by intercumulate melt during regional compressional deformation. A similar explanation is provided for the emplacement of the Tulameen Complex 150 km south of Kamloops (Findlay, 1969). As suggested for both the Paul Peak Stock
(Smith, 1979) and the Tulameen Complex (Findlay, 1969), the augite porphyry flows common in the enclosing Nicola Group may represent venting of the residual melt, suggesting a genetic link between the intrusive and extrusive rocks. The presence of folded dykes and fractures in the Heffley Lake Pluton support interpretation of these plutons as syndeformational. Thus a major compressional phase of deformation may be dated as 208 +I- 6.1 Ma.
Mount Fleet Alkali Complex
North of Paul Lake, several intrusive bodies, ranging from quartz monzonite northward to syenite, underlie the north shore of Paul Lake, Mount
Fleet, and Mount Lolo (Fig. 12). All three bodies intrude volcaniclastic rocks and limestone of the Harper Ranch Group, deforming surrounding Harper Ranch
Group sediments to schist or marble around its contacts. Several smaller bodies cropping out north of Mount Lolo and in the Dome Hills (Fig. 12) produced minimal contact metamorphism in the enclosing sediments. Igneous flow foliation defined by large feldspar laths in the syenite generally follows the circular pattern of the pluton (Webster and Ray, 2000). Deformation within the pluton apparently is limited to brittle movement. Zircons recovered from a sample of a small body of megacryst syenite southwest of Heffley Lake provide a crystallization age of 186.9 +I- 1.7 Ma for the pluton (Friedman et a/.,2002), corresponding to the Pleinsbachian stage of the Jurassic (time scale of Okulitch,
1999).
Tectonic History
Pre-Cretaceous rocks in the southern Canadian Cordillera record the evolution and accretion of volcanic- and oceanic-arc assemblages. Above, the stratigraphic succession of rocks in the area of Kamloops assigned to the
Quesnel Terrane is outlined and interpretations provided of the depositional controls on these successions. Below, these interpretations are expanded to include rocks believed correlative with those in the Kamloops area, within the
Quesnel Terrane as well as within the Chilliwack, eastern Klamath, and locally,
Slide Mountain terranes. Where similarities in depositional controls or unconformities exist between these areas, inferences are made regarding broader tectonic controls on deposition. Inferences are based on comparison of data reported in the literature. This section summarizes the chronology of events presented graphically in Figure 16. These "events," are recognized based on apparent changes in depositional or tectonic style and are presented as time slices during the Table 1. Details of fossil collections used to constrain distribution of units in Fig. 16
LITHOLOGIC UNIT GROUP^ DIAGNOSTIC FOSSIL I AGE I REFERENCE ( GSCI I I I I I Palmetolepis gracilis Orchard, 1987; see Orchard, larper Ranch Gp Mt. 1 CON sigmoidalis, lcriodus Harper Pebble Beds 1 costatus darbyensis 1 Be:gis/ 1987 Harper Ranch Gp I CON / Siphonodella duplicata l~arlyTournaisiad Beatty, 2002 1 C-305537
Late Visean - 1 Gnathodus bilineatus, G. early Harper Ranch Gp CON homopunctatus, Lochriea Serpukhovian / Orchard, 1987; commutata 1 1 Mississippian) 1 C-305564 Adetoanathus paraiautus, Early to Middle I I Harper Ranch Gp CON 'weetognatbus 'pp., permian Neostreptognathodus ~~~~~d~~",see Orchard (inclusive) 1 j spp., Neogondolella and Forster, spp. 1988 Metapoiygnathus primitius, Smith. 1979; 0-93450, Nicola Gp CON M. nodosus, M ,Mid Late Triassio / - this study Polvanatiformis C-305738 I I - - I 1 1 clast in Nicola Gp 1 CON / Sweetognathus sp. / Early Permian / this study 1 C-305763 Rossland Gp / AMM / Amioceras sp. 1 Sinemurian j Beatty, 2002 / C-305568 :last in Rossland Gp / CON / Sweetognathus white; 1 Early Permian / this study / C-305778 - - :last in nossl~ndGp rCONI E~igOndO1ejabidentata ex.g~. 1 Rhaetian j this study / C-305779 Chilliwack Gp COR Scohpora, Thamnopora Frasnian / / 1999 I NA Endothyra, Eostaffella, Late Mississippia Danner et a/.. Chilliwack Gp r/ 1 1 FUs 1 Millerella 1999 NA Pseudofusulinella, 1 Early Ieret a/., ' Op FUS Schwagenna, Parafusulinq 1999 NA Knob Hill Gp CON Palmatolepis spp. 1 Frasnian Fyles, 1995 C-167556 mrah, brachiopods, Carboniferous or Liflle, 1983 C-65087,62505 Attwood Gp 1 orthocone ceohalo~od Permian I I . . 1 I I Budrovignathus Brooklyn Frn CON Late Ladinian I Fyles. 1995 C-167562 I mungoensis 7 Flagstaff Mt. seq. CON Not Reported Mid Late Roback. 1993 / Devonian' / i NA Flagstaff Mt. seq. / CON ( Not Reported / Mississippian ( Roback, 1993 I NA I Mount Roberts Fm CON Idiognafioides SP Early Roback, 1993 I / / Pennsylvanian 1 i NA - Mount Roberts Fm 1 FUS / Schwaaerina / Earlv Permian 1 Roback. 1993 1 NA
I Neogondolella 1 Carnian-early / Robask, 993 Creek Fm 'ON ) polygnathifoms Norian 1 NA / t -- :last in Rossland Gp 1 FUS I Not Reported / Permian / Roback, 1993 / NA --i-'---- Arnioceras sp., / Sinernurian- Rossland GrDactylioceras, Coe/oceras/ Toarcian I Tipper, 1984 1I NA BragdonlBaird Frn / / Not Reported ate ~ississi~piadWatkins, 1985 / NA -- -- +--- WaagenOphyllid corahl McCloud Limestone j / Lower Permian Miller, 1987 1 schwagerinids I NA
i Rhaetian I 210 m+@G+ -,. : :. : :. : * Norian ...... 1 Nicola Gp I Eastern t ...... Facies r : ... : ... :-,I ' ...... '. .'", ... 'I - -- , I I ,- I I Ladinian I I :K,' I .+ -_240 I I . j MIDDLE I I , I 1 I UPPER 1 I I I I Z 260 - :a)MIDDLE I I I ...... t. -- Kungurian i K I I...... r.. Artinskian -. .... v ::. .. /' ...... LA ...... 0 ...... : :. . - .....1 -...... Sakmarian ------McGregor C I ' 290 4 Creek Fm . . Asselian . . . . a. - I. - - - .. -- - i ...... -i 1 r ~&l~merate Baird Frn pbr-- - ? .-.. __ South . : 'hompson,Fm . . in_dstye&br,/ ...... :. -- .... ---_*...... ragd don -~m: ...... , . : ... :'...... : ... : ... : a...... ~k'emlups;:; ...... Formation :.* ...... : ... :: ...... - ...... :: ...... :...:...:., Famennian I ...... I ...... zf 360 ' ? 0 - I>; Frasnian ...... 370 -1 -ii&+&ph evolutionary history of the rocks of the Kamloops area and, if possible, those of the aforementioned correlatives. Time slices are indexed with numbers along the right hand side of Figure 16; fossil data used to constrain the relative timing of events are detailed in Table 1.
1. Basement of the Quesnel Terrane
In the southern Canadian Cordillera, the basement may be represented by rifted parts of the North American craton (Struick, 1987), exotic continental crust, ancient oceanic crust, or a complex mix of these. In the Kamloops area, the oldest known rocks of the Quesnel Terrane are the upper Famennian Harper
Mountain Pebble Beds (F1, Table. 1, Fig. 16), although lower Famennian carbonate clasts in conglomerate attest to the presence of older strata (F3,Table.
1, Fig. 16). The southern Quesnel Terrane also contains basal strata of Late
Devonian age. The Knob Hill Group in the Greenwood, BC area, a succession of basalt and related sediments of mostly oceanic aspect and assigned to the
Okanagan Subterrane, contains rare limestones of Frasnian age (F14,Table 1;
Fyles, 1995). In the Trail, BC area, the Trail Gneiss is at least in part 380 Ma
(Sevigny et a/., 2003) and may represent crystalline basement or possibly the metamorphic root of a Late Devonian volcanic centre. The geochemical signature of the Trail Gneiss indicates it had little or no interaction with evolved cratonal basement (ibid). The Mount Roberts Formation may be in part correlative with the McGregor Creek Formation and locally unconformably overlies the Trail Gneiss. The Flagstaff Mountain sequence, cropping out south of and locally underlying the Mount Roberts Formation, contains limestones of
Frasnian and Famennian age (Roback, 1993).
Although sub-terranes of the Quesnel Terrane are distinguished based on their oceanic- or island-arc character, this does not imply pre-Mesozoic separation. Conversely, similar ages suggest a common time of inception.
Differences may therefore be a result of separate but related subjacent environments such as arc - back-arc settings.
The Sumas Mountain sub-group of the Chilliwack Terrane contains rare limestones bearing corals of Frasnian age (F1l,Table. 1) and likely rests unconformably upon deformed oceanic rocks of the Yellow Aster Complex
(Danner et a/., 1999). Thus basal strata of the Chilliwack Terrane are in part age correlative with the Quesnel Terrane.
Inboard of the Quesnel Terrane, rocks of pericratonic affinity record clastic sedimentation and volcanism related to a protracted history of rifting during the latest Proterozoic and early Paleozoic. Much of the correlations made between the western cratonal succession and pericratonic successions are based on these lower Paleozoic assemblages. Currently, there is no evidence to suggest the Quesnel Terrane existed at this time. Devonian-age volcanism and related plutonism is widespread within the Kootenay Terrane and is interpreted as evidence for eastward - dipping subduction (Schiarizza, 1989). Schiariua
(1989) suggests steepening of the subducting slab and consequent westward migration of the volcanic front during the Middle to Late Devonian resulted in the generation of the volcanic-arc associated with the Harper Ranch Group. 2. Early Mississippian transgression
Overlying the Harper Mountain Pebble Beds are mudstone and siltstone of early Tournaisian age recording a relative rise in sea level across the Devonian -
Carboniferous boundary. Further evidence for this transgression is provided by the conodont fauna present in the mudstone (F2, Table. I), which is representative of an outer-shelf biofacies (Beatty, 2002). This rise in sea level is coincident with a global transgression (Mawson and Talent, 1997) that is also recorded in strata of the craton (i.e. Devonian - Carboniferous Exshaw
Formation in the Canadian Rockies). Volcaniclastic sediments are common in the strata overlying the pebble beds implying basin subsidence was contemporaneous with the (re)inception of arc-volcanism. Lower Tournaisian strata have not been previously identified in the Quesnel, Slide Mountain,
Chilliwack, or eastern Klamath terranes and thus correlations at this time are problematic.
3. Mississippian volcaniclastic deposition
In the Kamloops area, volcaniclastic deposition occurred throughout most of the Mississippian, implying active, probably subduction related, volcanism at this time. Thick volcaniclastic packages are also present in the Chilliwack and eastern Klamath terranes and, although poorly constrained, are broadly correlative with the Tk'emlups Formation of the Harper Ranch Group.
Additionally the Milford Group, interpreted to be a pericratonic succession
(Erdmer et al., 2001) records volcaniclastic deposition at this time. The presence of a linear belt of Devonian - Carboniferous, subduction related volcanics and associated sediments is implied by sedimentary records in many of the pericratonic and eastern accreted terranes of the Cordillera. Given the apparently synchronous inception and growth of these island-arc assemblages during Devonian - Mississippian time, it seems likely that subduction was occurring along much of the western margin of the North
American craton.
4. Late Mississippian carbonate deposition
Late Mississippian carbonate, represented in the Kamloops area by the
South Thompson Formation (Fig. 13, F4, Table. I), is common in the southern
Canadian Cordillera (Orchard, 1991). The South Thompson Formation is interpreted as an arc-fringing carbonate that developed and aggraded rapidly due to volcanic quiescence. Volcanic quiescence is likely attributable to a break in, or cessation of, subduction.
The Red Mountain Limestone of the Chilliwack Group is correlated with the South Thompson Formation on the basis of fusulinid fossils (Fq2,Table. 1) and their common relative absence of volcaniclastic debris. The Bragdon
Formation in the eastern Klamath Terrane is at least in part Late Mississippian
(F2& Table. 1; Danner et a/., 1999), although here volcanism and volcaniclastic deposition is apparently coeval with carbonate bank sedimentation (Watkins,
1985). The Eagle Bay Formation of the Kootenay Terrane contains limestones of
Late Mississippian age (Unit EBP, Schiarizza and Preto, 1984), although slightly younger than those of the South Thompson Formation. However, at this time the Quesnel and Kootenay terranes were separated by the Slide Mountain Ocean precluding direct correlation of these units.
In the Quesnel, Chilliwack, and possibly Kootenay terranes, subduction is inferred to have ceased or slowed in Late Mississippian time. However, the eastern Klamath Terrane appears to record subduction-related volcanism throughout the Carboniferous (Bragdon and Baird formations). Thus, the
Quesnel, Chilliwack, and possibly Kootenay terranes are situated within the same tectonic regime at this time. Further cataloguing of Upper Mississippian limestone occurrences in the Cordillera is required to extend the limits of this tectonic regime.
5. Late Mississippian conglomerate deposition and Pennsylvanian uplift
Strata of Pennsylvanian age are rare in the Harper Ranch Group, and if present are most likely represented by the basal McGregor Creek Formation.
The Conglomerate Member of the South Thompson Formation is believed to represent uplift and erosion of the Late Mississippian volcanic-arc complex during the Pennsylvanian, but the timing of this event is poorly constrained. The
Old Goat conglomerate of the Chilliwack Group occupies a similar stratigraphic position to that of the Conglomerate Member, and may record Early
Pennsylvanian uplift in the Chilliwack Terrane. Strata of Pennsylvanian age appear to be absent or underrepresented in the Northern Sierra, Bilk Creek, and
Grindstone terranes (Miller, 1987), as well as in the Quesnel, Chilliwack, and less so, Stikine terranes. In the southern Quesnel Terrane, strata of the Mount Roberts Formation, in part correlative with the Harper Ranch Group, are at least locally Lower Pennsylvanian (FZ0,Table. 1).
This paucity of Pennsylvanian age strata in the Harper Ranch Group and its correlatives (Fig. 16) suggest a regional tectonically controlled unconformity developed during this time. Controls on the development of this unconformity are unknown, although evidence exists for the amalgamation of Wrangellia and
Alexander terranes during the Pennsylvanian (Gardener et a/., 1988). If this was a factor it necessitates spatial relationships between the above-mentioned terranes similar to that of today. These particular relationships are difficult to reconcile with current paleomagnetic and paleobiogeographic data.
6. Permian carbonate deposition
Lower Permian limestone, represented by the McGregor Creek Formation in the Kamloops area, is common in the Canadian Cordillera (Orchard, 1991).
The thickness of the McGregor Creek Formation is relatively uniform and volcaniclastic detritus is notably absent. This unit is interpreted as a carbonate platform developed on a stable, slowly subsiding shelf.
The McGregor Creek Formation has been included in a Cordilleran-long belt of Lower Permian rocks (McCloud Belt) characterized by mixed Tethyan and
North American faunal characteristics and first recognized in the lower Permian
McCloud Limestone (FZ7,Table. 1) of the eastern Klamath Terrane (Miller, 1987).
The presence of these mixed fauna has been explained by invoking longitudinal separation from North American craton at this time (Belasky and Runnegar,
1994; Belasky et a/., 2002). Thus, a large ocean (Slide Mountain Ocean) is inferred to have existed between the McCloud Belt and the pericratonic successions.
Alternatively, faunal differences may have developed due to reconfigured oceanic circulation established by the presence of the supercontinent Pangea, which stretched pole to pole. In this hypothesis, constriction of temperate regimes on the craton may have been brought about by equatorially directed ocean gyres. McCloud Belt fauna would then need to have been positioned west of the influence of these gyres and consequently would have an anomalously warmer water signature than latitudinal equivalents on the craton (see
Henderson and Mei, 2001). If this is true the need to telescope a wide Slide
Mountain ocean in the Late Permian is negated. This is in agreement with the paucity of evidence for Permian-age magmatism within the Harper Ranch subterrane (Ferri, 1997).
In the Nelson, BC area, rocks of the Mount Roberts Formation, correlative in age with the McGregor Creek Formation, contain schwagerinid fusulinids among other McCloud Belt fauna (F21, F22, Table. 1). Additionally, rocks in the
Atwood Group are at least in part Lower Permian (FI5, F17, Table. 1) and thus, age-correlative with the McGregor Creek and Mount Roberts formations. The
Black Mountain Limestone of the Chilliwack Group is also Lower Permian and correlative with both the McGregor Creek Formation and the McCloud belt based on fusulinid fauna (FI3, Table. 1).
Clastics of the Mount Roberts Formation contain Proterozoic-age detrital zircons of probable continental origin (Roback and Walker, 1995). Thus proximity to continental crust is implied. Proterozoic detrital zircons have also been recovered from the Lay Range Assemblage (included in the Harper Ranch
Subterrane) in northern BC (Wheeler and McFeely, 1991; Ferri, 1997). These detrital zircons have been used to support theories of rifted continental crust underlying the Harper Ranch Subterrane (Roback and Walker, 1994; Ferri,
1997). Mechanisms for this theory are presented by Struick (1987) and further explored by Erdmer et a/. (2001).
7. Late Permian to Middle Triassic deformation
In the southern Canadian Cordillera, evidence exists for deformation sometime during the Late Permian to Middle Triassic. Most notable is the sub-
Triassic unconformity (Read and Okulitch, 1977). In the Kamloops area, the
Nicola Group unconformably overlies the McGregor Creek Formation, although the stratigraphic position of this contact is debatable (Fig. 15). Regardless, abundant Lower Permian limestone boulders in Late Triassic conglomerate imply topographic relief at the time of deposition.
Rocks of the Chapperon Group, correlated with the Harper Ranch Group, contain evidence of folding and metamorphism prior to the deposition of the
Nicola Group (Read and Okulitch, 1977). Oceanic rocks of the Knob Hill Group are tectonically interleaved with island-arc rocks of the Attwood Group prior to the deposition of the Brooklyn Group in the late Middle Triassic (FI6, Table. 1) (Fyles,
1995). Thus it seems reasonable that the Knob Hill and Attwood Groups were exposed and provided detritus for the Brooklyn Conglomerate, as indicated by the presence of Lower Permian limestone cobbles in the conglomerate (FI7, Table. 1). Dostal etal. (2001) interpret these relationships to imply the Slide
Mountain Ocean was little more than a marginal seaway at the time. Conversely, evidence of extensive pre-Middle Triassic structural imbrication of strata of the
Antler Formation (Struick and Orchard, 1985), Eagle Bay Assemblage, and
Fennell Formation (Schiariua, 1989), all parts of the Slide Mountain Terrane, do not preclude the telescoping of a much more extensive back-arc ocean.
The Upper Triassic to Lower Jurassic Cultus Formation of the Chilliwack
Terrane disconformably overlies the Lower Permian Black Mountain Limestone
(Danner et al., 1999), although pre-Triassic deformation has not been reported.
In the eastern Klamath Terrane, Middle to lowermost Upper Permian volcanogenic sediments of the Bollibokka Group are overlain by the Middle
(Lower?) Triassic Pit Formation (Miller and Harwood,1990). Here, Late Permian to Early Triassic deformation is implied (ibid).
8. Late Triassic volcanism and sedimentation
The Nicola Group and its correlatives in the Canadian Cordillera record magmatism and related sedimentation in the Late Triassic (F6, FZ3,Table 1).
Magmatism has been interpreted as the result of east dipping subduction
(Mortimer, 1987); this may have resulted in the amalgamation of discrete upper
Paleozoic lithotectonic elements such as the Cache Creek, and lower Quesnel terranes. Isotope studies (SmINd) on Upper Triassic successions in the southern
Canadian Cordillera indicate both continental- and island-arc provenance of siliciclastics (Untershutz et a/., 2002). Nicola Group correlatives in the Slide Mountain Terrane (e.g. the Slocan Formation) provide stratigraphic links between terranes, further constraining their position at this time.
9. Late Triassic deformation
Stratigraphic relationships in the Kamloops area imply deformation of
Harper Ranch and Nicola group units prior to the deposition of the Lions Head
Volcanics of the Rossland Group. The sub-Jurassic unconformity exposed east
of the Lafarge Quarry (Fig. 12) records Late Triassic to Early Jurassic uplift and
erosion, although in the northern part of the study area this relationship is
equivocal. Rhaetian age limestone clasts (Flo, Table. 1) in the basal Lions Head
Volcanics suggest syndeformational carbonate production during latest Triassic time. Lower Permian clasts of the McGregor Creek Formation (F9, Table. 1) are also present. Conglomerates lithologically and stratigraphically correlative with the basal Lions Head Volcanics occur north and south of the Kamloops area.
North of the study area, Lower Jurassic conglomerate sits atop Windy Mountain in the Clearwater, BC area, and incorporates Permian limestone (Campbell and
Tipper, 1971), although the stratigraphic nature of this contact is debatable (P.
Schiarizza pers. com., 2001). In the Nelson area, basal conglomerate of the
Rossland Group overlies and incorporates Lower Permian limestone of the
Mount Roberts Formation (F24, Table. 1). Additionally, Miller and Harwood
(1990) report a Triassic-Jurassic unconformity in the eastern Klamath Terrane.
Several hypotheses regarding the development of the Rayleigh
Conglomerate, primarily concerning the sense of motion on the Dome Hills Fault, were presented above (Fig. 15). Figure 15B shows reverse motion on the Dome Hills Fault. Directly west of the Dome Hills Fault, along Peter Peak Ridge, mudstone and siltstone of the Dome Hills Succession is folded into a syncline - anticline pair (Smith, 1979). Notably, folds of this scale were not recognized in the Armour Creek Succession or the Harper Ranch Group. Folding may have resulted from thrust emplacement of relatively competent Harper Ranch Group strata over the relatively incompetent Nicola Group. Foliation in the Dome Hills
Succession likely represents axial planar cleavage related to folding. If so, steep eastward dips suggest these are west verging structures. In the Shaw Hill area cleavage developed in the Rayleigh Conglomerate and the Armour Creek
Succession is steep and both east and west dipping (backpocket figure BP-1).
1 0. Latest Triassic intrusion
Plutons of Late Triassic age are common in the Nicola Group (Mortimer,
1987). In the study area, the Heffley Creek Pluton and the Paul Peak stock are dated and interpreted as latest Triassic respectively. These plutons were emplaced syndeformationally (Smith, 1979; Friedman et a/. , 2002; detailed above) and broadly date the deformation as 208 +/- 6.1 Ma. The Guichon Creek batholith intrudes Carnian age Nicola Group southwest of the study area and has a crystallization age (zircon) of 210 +/- 3 Ma (Mortimer etal., 1990). The Josh
Creek Diorite intrudes the Mollie Creek Assemblage (a possible correlative of the
Mount Roberts Formation) in the Christina Lake area in southern British
Columbia and was emplaced ca. 215.9 +/- 1.4 Ma (Acton et al., 2002). The diorite displays one phase of deformation and is overlain by undeformed Lower Jurassic Rossland Group (ibid). Late Triassic syndeformational plutonism is therefore implied for much of the southern part of the Quesnel Terrane.
11. Deposition of the Rossland Group
In the Kamloops, Barrier, and Nelson areas, Rossland Group rocks or their correlatives overlie Triassic or older strata with angular unconformity.
Rossland Group units are mainly of island-arc affinity and record renewed volcanism after apparent Late Triassic deformation. In the Kamloops area, the
Lions Head Volcanics appear to be lower metamorphic grade than underlying units in both the Nicola and Harper Ranch groups. Latest Triassic conodonts isolated from conglomerate clasts (sample 01-OF-B-228 Appendix D) in the
Lions Head Volcanics are variably altered to Conodont Alteration Index (C.A.I.) 5, implying heating of approximately 350' C, although some evidence of hydrothermal alteration is apparent. The base of the Lions Head Volcanics is
Lower Sinemurian based on ammonite collections (F8, Table. 1); the upper age limit is unknown. In the type area, parts of the Rossland Group are lithologically similar to the Lions Head Volcanics. Here the unit ranges from Sinemurian to
Toarcian. The Cultus Formation in the Chilliwack Terrane is locally as young as
Pliensbachian (Smith et al., 2001) and thus is partially correlative with the
Rossland Group, although limited data restrict this correlation.
Conclusions
Refined stratigraphy in the Kamloops area provides the basis for tectonic interpretations for the evolution of the Quesnel Terrane. Changes in depositional character and major unconformities are interpreted as tectonically controlled
110 where synchronous within the Quesnel Terrane and more so where synchronous between the Quesnel and other terranes. Inception of subduction west of the cratonal margin during the Middle to Late Devonian is implied by the widespread occurrence of island-arc and back-arc 1 oceanic units of this age (Fig. 16).
Crystalline basement and strata older than Middle Devonian are rare.
Pennsylvanian deformation is suspected from the general paucity of rocks of this age in the Quesnel and Chilliwack terranes, although the duration, extent, and intensity of this event are unknown. Late Permian - Middle Triassic deformation is widespread and better understood in the southern Canadian Cordillera (Read and Okulitch, 1977). Apparent, latest Triassic deformation is prevalent on the eastern margin of the Quesnel Terrane and may be related to widespread plutonism at this time. The cause of this deformation is unknown. REFERENCES
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Five stratigraphic sections, totaling > 3500 metres, were measured in the study area and are presented in the following appendix. True bed thicknesses were attained by extrapolating from the local dip and measurements of apparent thickness from 1:20 000 scale maps, or the use of a 1.5 metre Jacob's Staff
equipped with a clinometer. Each measured section documents, where possible,
lithology, grain size, general bedding thickness, sedimentary structures, trace
and body fossils, bedding orientation, and quality of exposure.
Table A-I provides a list of section locations in UTM coordinates. Figure A-I
is a legend of measured section symbols for the subsequent logs.
Table A-I
Section # Unit Easting Northing Description
Tkl Tk'emlu~s 699568 561 8345 type section Fm.
Tk2 Tk'emlu~s 702091 5617747 reference section Fm.
type section (conglomerate South member); reference section ST1 Thompson 702912 71 37 (early carbonate, sandstone Fm. member)
South type section (early carbonate, ST2 Thompson 704468 5617206 sandstone member, late Fm. carbonate)
Mcl McGregor 706430 561771 3 type section Creek Frn. Figure A-1. Legend for measured sections of Appendix A.
Rock Tvpes Svmbols
limestone Sedimentary Structures rip-up clasts cherty cherty limestone chert nodules argillaceous limestone pyroclastic rich (> 30% pumice)
0....*.72. ... chert pebbles ...... -;-.I. .. sandstone synsedirnentary folding mudstone with thin sandstone trough cross-bedding mterbeds discontinuous lamination mudstone planar lamination breccia breccia clasts dike conglomerate fault
.&-.+.;. calcareous sandstone Fossils I Trace Fossils plant fragments covered interval brachiopods Exposure
fusulinids
conodonts fair I corals pelmetazoans poor (>< % for sandstones)
Grain Size root casts bioturbation (indet.) Grain Size Scale Grain Size Scale clastics carbonates Teichichnus Planolites
s ss sand 'ig. A2-a Tk'emlups Formation Section TKI -1 DESCRIPTION
~udstonelsiltstone: mudstone beds >icker and more common than iltstone
rolcaniclastic sandstone: thick v. :oars0 sand debris flow, fines upward werlainnudstonelsiltstone by planar laminated nudstonelsiltstone: massive mudstone with rare thin siltstone interbeds' "Inor soft sediment deformation 'below ,~ltstonebeds nudstonelsiltstonelsandstone' nudstone content increases upward; Im thick v coarse volcaniclastlc sand ~-lo%~crtndoiddebris near base :r~no~dsdecrease upward; normal iiltstonelsandstone: overall grain size ncreases upward; bases of sandstone mds commonly loaded, photo A-35 nudstonelsiltstonelsandstone: 7m !.coarse volcaniclastic sandstone with 3rosive base; mudstonelstltstone' nudstone rlo-uos 1-3m above base: )hto ~5431-17'above base nudstonelsiltstonelsandrtone: 1-3m !.coarse volcaniclastic sandstone beds ;cour and load underlying nudstonelsiltstone. mudstone rip-ups :oncentrated -30c'm above bases nudstone breccia: Doorlv sorted. angular, coarse to pebble slzed nudstone grams supported by :alcareous matrlx: poorly indurated, 90ssibly related to faulting
landstone med~umvolcanlclastlc sandstone wltn part~ally calcareous :ement. abundant well rounded to .ounded It grey chert
slltstone silty, mudstone: siltstone predomjnhtes w~th.mudstone stringers; =-Im thick andeslt~cdlke 219152 siltstone. siltv mudstone, vt. sandstone: prbmment sllckensides trend 3001plunge 35 conugate Set trend 0061olunoe 16; s~ickensldezone ;3m- ~id~:~~e&iina~chaoticand local1 - Tk'emlups Section TKI -2 DESCRIPTION
mudstonelriltrtone: siltstone beds have sharp basal contacts- soft sediment deformation appaient in mudstone beds. overlain b -10m massive volcaniclastic sanJstone
sandstone. c to vc volcaniclastic sandstone
mudstonelriltrtone: grainsize generally decreases up section mudstonelsiltstonelsandrtone: grains~ze generally increases up section
mudstonelsandstone: pumice rich c to rc volcaniclastic sandstone interbedded ~ithmudstone; sandstone beds ncrease In th~ckness u section; rare mudstone rip-ups, pebbk lineation 347
patchy outcrop; massive mudstone and coarse pumtce rich, volcaniclastic sandstbne; contacts not exposed
mudstonelsiltrtone: argillaceous mudstone with rare silt interbeds siltstone, content increases up se'ction; soft sedlment deformatton aDDarent In mudstone underlying siltstone' beds sandstone: coarse volcaniclastic debris flow reverse graded (f to v.coarse) at bas6 normally graded 50cm above base' granule to pebble sized pumice and inudstone clasts mudstonelslltstonelsandrtone: argillaceous mudstone overlain by Interbedded mudstonels~ltstone/vf. sandstone. yroxene (augite) porphyry (possible iilP) mudstonelbeddad chert: 10-3Ocm thick 3eds with undulatory contacts; h~ghly fractured
nudstonelriltstone: mudstone beds :bicker and more common than jlltstone LITHOLOGY 7g. A2-c Tk'emlups Formation GRAIN SIZE !! 0 Siliclclastics PE Section TKI -3 n. n. iz - DESCRIPTION
Ilmestone: heavily weathered and fractured mudstone, grainstone, and packstone
siltstonelsandstone: planar bedded siltstone and fine sandstone
exposure in woods
sandstone: rned to coarse volcanlclastic sandstone cliffy exposure in the woods.' difficult to navlgate uds elsiltstone: very fractured
sandstone: coarse volcaniclastic sandstone, angular rnudstone and purnlce rams overlaln b Interbedled rn'udstone andY slltstone
mudstonelsiltstonelsandstone: overall 6-1: grainsire increases up sectlon' overlain by rn to c volcan~claitic - sandstone: base of sandstone scours 7g. A3-a Tk'emlups Formatior Section TK2-1 DESCRIPTION
~iltstonelv.f.sandstone: siltstone dominates rare mudstone strinoers: sdty horlzon moderately b~oturb-ited
sandstone: coarse volcanlclastic sandstone sharply overlies mudstone: coarsens upward to granule sand ovel 2m fines from here and overlain bv mudstonels~ltstoneafter 6m sandstone: coarse volcaniclastic sandstone erosively (75cm relief) overlies mudstone' rare -50cm diameter angular mudstone rip-ups near base- grainsize and rounded mudclast bontent Increases through mudstonelsiltstonelsandstone: interbedded mudstone/siltstone/vf. Sandstone. sand beds have sharp. loaded babes sandstone: fine planar laminated sandstone with 'sharp loaded base, fines up to siltstone over 40cm' overlain by identical succession' at 4.2m Bedding parallel fault, photo C-1.2 mudstone: massive mudstone with rar slltstone interbeds. siltstone beds -4- lOcm thick, with ihar bases and parted by thln mud srringers
sandstone: coarse volcaniclastic sandstone, fines u ward: overlaln by mudstonelsiltstone 8m above base
sandstone:, pumice rich, coarse volcan~clast~csandstone fines u ward overlain by rnudstonelsiitstone 4.9m above base
sandstone:, pumice rich, coarse volcan~clast~csandstone. olanar bedde 8m~abovebase, fines upward from here- overla~nby mudstonels~ltstone I0m 'above base
mudstone/slltstone: interbedded mudstone/siltstone~ soft sediment deformation oervabive
sandstone: coarse volcaniclaptic sandstone: f~nesu ward to flne sand sized 10m above Ease
mudstonelslltstone: massive ar ~llaceous mudstone (chert) with rar sifistone interbeds; -. 4.A3-b Tk'emlups Formatior Section TK2-E DESCRIPTION
sandstone: coarse volcaniclastic sandstone -4m thick bed
sandstone: granular volcaniclastic sandstone eroslvely overlles slltstone; mudstone rl ups and pumice Clasls rhoto C-11~'conce~tratednear the ase: fines to med~umsand at top; 30cm dlameter pumice clasl occurs 4m from top plant fossils In talus
sandstone: very coarse volcaniclastic sandstone large mudstone rlp-ups concentrat'ed near base. sharply overlain by siltstone -1'0m above best
alltstonelfine sandstone: thin mudstone interbeds common in slltstone beds. 3 >2m thick coarse ~olcan~~la~i~~~'sands~onebeds present from 8-442
sandstone: very coarse volcaniclastic sandstone eroslvely overlles mudstone no aooarent mudstone oebbles: fines uowaid to fine sandstone 8m above base
sporadic outcrop; mostly mudstone/slltstone, rare fine
sandstone: massive, fine volcan~clasti sandstone
siltstonelmudstone: siltstone dominate
sandstone. verv coarse volcaniclastic sandstone eroske~y (2m rel~efover 20m) overlles mudstone lar e mudstone clasts concenirateB 1 Sm above base of flow, flnes upward lo sandstonelsiltstone. masslve fine volcaniclast~c sandstone interbedded with siltstone: sandstone has disti.nct lioht oreen fresh colour: b~oturbatlon aiparint In muddler s~ltstone horizons
sandstone: very coarse volcaniclastlc sandstone eros~velv (2m relief over 20m) overlies mudstone- lar e mudstone clasts concqnirate8 2-3m above base of flow, fmes upward fror here. Fig. *3-c Tk'emlups Formatior Section TK2-C DESCRIPTION
sandstone: vf sandstone forms Small cliff; honeycomb weathering (Photo C- 21)
mudstonelsiltston~lsandstone: beds openl folded?; rare echinoderm debris rich Xne sandstone beds
sandstone: ver coarse volcaniclastic sandstone: 6m tiick
mudstonelsiltstonelsandstone: patchy outcrop to here
massive siltstone at top of ridge
sandstone: very coarse, pumice rich volcaniclastic/p roclast~csandstone; eros~onal basar contact deforms underlying mudstone (Photo C-20). fine upward to fine sand 5m aboh base
sandstone: coarse volcaniclastic/pyrocla~icsandstone; fines to medium gramed planar bedded and composil~onally graded pum~cell~th~crlch sand
mudstone rip-up clasts aligned along bedd~ng. gradual1 fines to fine sandstoile 14m a\ove base sandstone: medium volcan~clastic/pyrpclastic sandstone' eros~onally overl~ess~ltstone (40cni relief). fines rapidly to siltstone -2117 above' base
sandstone: fine to medium volcaniclastic/pyroclastic sandstone beds w~thsham occas~onallv loaded bases; very puinice rich ; r'are siltstone ~nterbeds:
sandstone: coarse volcaniclastic sandstone -4m th~ck bed Section TK-4 0 a 2 5 Sandstone* S? 46 n n DESCRIPTION E ZX tm c95
mestone: heavlly weathered and .actured mlcrite, gralnstone, and ackstone ~udstonelsiltstone s~ltstone omlnates overlam by pdmlce r~ch ne ~ra~nedsandstone, and masswe 111stone andstone: coarse vc sandstone. oarsens upward to granule ver "mice rich, hand sample 6-456i South Thompson Formation Fiq. A4-a Section ST-1 DESCRIPTION
limestone: mlcrlle, algal lam~naled moslly covered
conalornerate: weli rounded. oebble lo cobb7e %zed siltslone and-limeslone clasts In calcareous very coarse- ra~nedvolcan~clasl~c sandstone malrix il are very coarse sandstone cobbles. Some lhmestone cobbles contain coral macrofossils Aua~teoorohvrv dike (245171) crops oZt 2m tieibw outcrop.
sandstone: masslve, med~umgra~ned. purple coioured sandstone F~nes upward lo purple sillstone Trou h cross-beddlno hlahllahted in sanjstone by rare rnud?ton? d7a es Rare dlsconlinuous micrite Penses apparent in upper art of sillstone. Here sl~tstoneP lnes to mudstone and IS allernal~na oreen and ouroe coloured So11 peds" a'pparenl In 'mudslone
while and black pumice. sandstone: line calcareous (cemented?) sandstone, approximalely 5 m above massive carbonate
limestone' heavily weathered and fractured mlcrite ralnslone. and packstone, rare 'sltcilied corals. s~l~c~f~edbrachiopod beds occur in
crinoid molds. At contacl with limestone 40 Cm bed of crinoidal packslone lnlerbedded wllh masslve slltslone. Mudslone bed overlles this and contalns lhin packstone Interbed. Grainstone and packstone overlies mudstone, contact is sharp and undulat~ng.
volcaniclastic sandstone: coarse vc sandstone, coarsens upward to ranule, very umlce rich hand sample 8-456b. lhen Yines over i0 metres lo fine- prained sandslone: th~scycle repeals wo more l~rneslhen covered unt~lB- 45 7 LITHOLOGY South Thompson Formatior GRAIN SIZE .. Siliciclastics Section ST-: i:w Fig. A4-b 6 Sandstone; ; F ='YI n 0 DESCRIPTION 8 2% fm cBS
:ongolomerate: I~mestone,slllslone. dolcan~c Ihth~c, and chert pebble :onglomerale Top not seen
;andstone: fine-gralned sandstone and ;~llstone, alternal~ngpurple and green :oIoured imestone: thin micrile bed
iiltstone: fines upward lo mudslone
:ongolomerate: Ilmestone, stltstone lolcanlc l~thlc,and chert pebble :onglomerale.
imestone: 20 cm micrile bed
:ongolomerate: Ilmeslone, slllslone. lolcan~clithlc, and chert pebble to :obble congtomerale Three stacked jebrfs flows
landstone: very coarse to granule lralned volcaniclasl~csandstone, rare
iandstone: coarse- rained lolcan~clast~csandsgone.
congolomerate: Ilmestone, slltstone. dolcanlc Illhlc, and chert pebble lo :obble conglomerale Clasl supporled 11 base Inverse graded base. .ema~nder normal raded Very coarse grained volcanlclas?lc sandstone matrlx iandslone: coarse- ralned calcareous ,olcan~clast~csandsgone, rare 3 rnm Ilametre pyrlte, flnes u ,ver 2 m, over~a~nby Fln2g:ilFJ:ne ,andstone wlth d~spersed carbonaceous naler~al(plant stems')) South Thompson Formation Fig. A5-a Section ST2-1 DESCRIPTION
covered: abundant augite porphyry In float wackel rainstone: brachiopod shell debris %eds
conglomerate: limestone cobble to k;lznm;ib"m;;8',withsharply calcareoys overlles caicareous sandstone: Rare chert cobbles become increasing1 common ups section. Fines to cherr pebble -conglomerate wlth caicareous matrtx. sandstone: calcareous red, sandstone. poorly sorted mlxed volcanlclastlc 1 carbonate sand. Numerous skeletal elements including solitary corals. Scoured bedding contacts.
sandstone: massive, fine to medlum gralned volcanlclastlc sandstone, dark purple 'cotour. No sedimentary structures vlslble.
nicrite: massive, highly fractured, dark :alcareous mudstone
packstone: thin bedded recessive. Numerous 10-30 cm thlck brachiopod debris beds (Sample T2-6b). wackelpackstone: brachio odfloatstonea 43m. ~odularchertbedat4fm. wackelpackstone: 20 cm thick nodular chert bed at 41 m. oackstone: thin bedded recessive backstone mterbedded wlth metre scalc masswew pacltstone Cr~nolddebrls vlslbie on beddlng planes wackestone massive highly ,fractured; silicified brachiopods 'and solitary rugose corals wackelpackstone: massive, outcrop very steep -. McGregor Creek Formatior -1g. A6-a Section MC 1-' DESCRIPTION
rainstone: dark crlno~dal gramstone, lllclfled fractures, common cherty oduies
ackstone I wackestone: masslve sdded. common crlnotd allochems are 30 - 50 cm th~ck slllc~f~ed neslone beds, common cherl nodules
'ainstone: medlum gralned, common lerl nodules, rnasslve outcrop
icrite: masslve. hlghly fraclured, dark Icareous mudslone
ackstone: open folds s~llc~f!ed oductld and splrlferld brachlopods
ainstone: bloclasllc 20 - 40 cm ck beds. common ;olltary corals and lc111ed brachlo~ods
ackestone: dark grey, some s~llclfied ach~opods
C 2c Y C 3
c 2? mL m
C 0 5 ZE' *0 2ELL I-
r. r. 0 r. r (D LO
LO 0 v(0 0 r.
0 r
2 q : 8 0 0
m r m (0 0 3 0 GSC Field Fauna number number ZoneUTM Easting Northing Unit
Carboniferous, South indefinite within 00-OF-B-ST- Eostaffella sp. ex gr. coopen (Zeller) C-306321 7081 67 561 9973 Thompson middle Visean- 03b Eostaffella sp. Fm. early Bashkirian interval
Carboniferous, South indefinite within 00-OF-B-ST- Mediocris breviscula (Ganelina) C-306322 704605 561 7077 Thompson middle Visean- 26b Pseudoendothyra columbiana (Sada and Danner) Fm. early Bashkirian interval
Carboniferous, South Eostaffella sp. ex gr. E. kasakhstanica Rauser- indefinite within 2 w C-306323 00-OF-B-ST-X 10 704605 561 7077 Thompson Chernousova middle Visean- 03 Fm. Eostaffella sp. early Bashkirian interval
Carboniferous, indefinite within South Pseudoendothyra sp. ex gr. P. columbiana (Sada middle Visean- C-306324 00-OF-B-ST-Y 10 704605 561 7077 Thompson and Danner) Fm. early Bashkirian interval GSC Field UTM Easting Northing Unit Fauna number number Zone
Mediocris breviscula (Ganelina) Carboniferous, Mediocris cupellaefomis (Ganelina) South indefinite within 00-OF-B-RL- Eostaffella sp. C-306325 10 708167 5619973 Thompson middle Visean- 03b Eostaffellina sp. ex gr. E. protvae (Rauser- Fm. early Bashkirian Chernousova) interval Pseudoendothyra columbiana (Sada and Danner)
00-OF-B-UH- McGregor C-306309 708966 5618864 Creek Fm. Barren Unknown 07b
Carboniferous, South indefinite within C-305543 00-OF-B-SH-36b 10 702653 5622521 Thompson Mediocris breviscula (Ganelina) middle Visean - Fm. early Bashkirian interval
Carboniferous, South indefinite within C-305544 00-OF-8-LO-1 10 702763 5622415 Thompson Eostaffella sp. A middle Visean - Fm. early Bashkirian interval
Carboniferous, South indefinite within C-305545 00-OF-B-LO-4 10 702722 5622369 Thompson Pseudoendothyra sp. lndet middle Visean - Fm. early Bashkirian interval
-C' C g .gC'C c .s 2g &:E g.z,,-m .L g'~aY-. .EJ='" corm .+s>g$ bsgr o cam- oc_am- e%= >.C e%ij >.r mu'O= mu'O = O.GEE O.CEE GSC Field Fauna number number ZoneUTM Easting Northing Unit
McGregor C-305572 00-OF-B-WL-8 10 706634 5617635 Creek Fm. Barren Unknown
Carboniferous, South Mediocris breviscula (Ganelina) indefinite within C-305574 00-OF-B-WL-16 10 705877 56181 65 Thompson Mediocris sp. ex gr. M. mediocris (Vissarionova) middle Visean - Fm. Plectostaffella sp. early Bashkirian interval.
Late McGregor Carboniferous C-305575 00-OF-B-RL-00 10 708627 56 19559 Creek Fm. Fusulinacean fragments with keriotheca (Kasimovian) to Middle Permian
Carboniferous, South Eostaffella cooperi (Zeller) indefinite within C-305577 00-OF-B-RL-02 10 708552 5619760 Thompson Eostaffella sp. ex gr. E. mosquensis Vissarionova middle Visean - Fm. Plectostaffella sp. early Bashkirian interval
Carboniferous, South indefinite within C-305578 00-OF-B-RL-03 10 708167 5619973 Thompson Pseudoendothyra sp. indet middle Visean - Fm. early Bashkirian interval
GSC Field UTM Eaoting Northing Unit Fauna number number Zone
Carboniferous, South Mediocris breviscula (Ganelina) indefinite within C-305590 00-OF-6-ST-20 10 704496 5617181 Thompson Eostaffella sp. middle Visean - Fm. Millerella sp. early Bashkirian interval
Carboniferous, South indefinite within C-305591 00-OF-6-ST-24 10 70461 6 5617072 Thompson Eostaffella sp. middle Visean - Fm. early Bashkirian interval
Carboniferous, South indefinite within 2 Mediocris breviscula (Ganelina) C-305592 00-OF-B-ST-25 10 middle Visean - 0 704635 5617079 Eostaffella sp. ex gr. E. curnbedandensis Rich Fm. early Bashkirian interval
Mediocris breviscula (Ganelina) Carboniferous, South Mediocris sp. ex gr. M. cupellaefomis (Ganelina) indefinite within C-305593 00-OF-B-ST-26 10 704605 5617077 Thompson Eostaffella sp. ex gr. E. prisca ovoidea Rauser- middle Visean - Fm. Chernousova early Bashkirian Pseudoendothyra columbiana (Sada and Danner) interval
Carboniferous, South Mediocris sp. indefinite within C-305594 00-OF-B-EH-13 10 706670 5619384 Thompson Eostaffella sp. middle Visean - Fm. Plectostaffella sp. early Bashkirian interval GSC Field number number ZoneUTM Easting Northing Unit Fauna
Carboniferous, .. Mediocris breviscula (Ganelina) soutn- indefinite within Mediocris sp. ex gr. M. parapama (Ganelina) C-305595 00-OF-B-EH-21 10 707203 5619076 Thompson middle Visean - Eostaffella sp. Fm. early Bashkirian Millerella sp. interval
Carboniferous, South Mediocris sp. ex gr. M. mediocris (Vissarionova) indefinite within C-305596 00-OF-B-EH-22 10 707228 5619036 Thompson Eostaffella sp. middle Visean - Fm. Pseudoendothyra sp. early Bashkirian interval
McGregor C-305597 00-OF-B-EH-26 10 707228 5619036 Creek Fm. Barren Unknown
Tk'emlups C-305598 00-OF-B-SL-05 10 699262 5623798 Barren Unknown Fm.
South C-305599 00-OF-B-SL-12 10 699909 5622870 Thompson Barren Unknown Fm.
South C-305600 00-OF-B-MH-06 10 7101 19 5622399 Thompson Barren Unknown Fm. GSC Field UTM Easting Northing Unit Fauna number number Zone
Late McGregor Carboniferous C-305601 00-OF-B-MH-10 10 710088 5621217 Creek Fm. schwagerinids (Kasimovian) to Middle Permian
McGregor C-305602 00-OF-B-MH-I I 10 710212 5621217 Creek Fm. Barren Unknown
McGregor C-305604 00-OF-B-TB-06 10 707076 5623042 Creek Fm. Barren Unknown
Early McGregor Fusulinacean fragments, probably Carboniferous C-305605 00-OF-B-TB-07 10 707126 5622992 Creek Fm. 3 pseudoendothyrids (middle Visean) to Permian
McGregor C-305606 00-OF-B-TB-08 10 707123 5622918 Creek Fm. Barren Unknown
------McGregor C-305607 00-OF-B-TB-09 10 706970 562281 1 Creek Fm. Barren Unknown
McGregor C-305608 00-OF-B-TB-10 10 706834 5622861 Creek Fm. Barren Unknown GSC Field Fauna number number ZoneUTM Easting Northing Unit
Late Carboniferous McGregor C-305609 00-OF-B-TB-15b 1O 708306 5621648 Creek Fm, Quasifusulina sp. lndet (late Kasimovian) to Early Permian (Asselian).
Late McGregor Carboniferous C-3056 12 00-OF-B-TB-20 10 709651 5621816 Creek Fm. (Kasimovian) to Middle Permian
Late McGregor Carboniferous C-305613 00-OF-B-TB-29 10 706965 5621365 Creek Fm. schwagerinids (Kasimovian) to A P Middle Permian
Late McGregor Carboniferous C-305614 00-OF-B-TB-31 10 706814 5621266 Creek Fm. (Kasimovian) to Middle Permian
C-305615 00-OF-B-TB-32 10 706765 5621251 I Barren Unknown
C-305616 00-OF-B-TB-34 10 706332 5621453 I Barren Unknown
C-3056 17 00-OF-B-TB-35 10 706289 5621 505 I Barren Unknown
C-3056 18 00-OF-B-TB-36 10 706076 5622073 I Barren Unknown GSC Field Fauna number number ZoneUTM Easting Northing Unit
Late McGregor Carboniferous C-305619 00-OF-B-TB-37 10 705703 5622284 Creek Fm. schwagerinids (Kasimovian) to Middle Permian
C-305620 00-OF-B-TB-39 10 705405 5622291 I Barren Unknown
C-305623 00-OF-B-TB-47 10 702899 56171 35 I Barren Unknown
C-305624 00-OF-B-TB-48 10 703752 5617548 I Fusulinacean fragments(?) Unknown
McGregor C-305625 00-OF-BAQ-10 10 707858 5617308 Creek Fm. Fusulinacean fragments(?) Unknown
6 McGregor C-305626 00-OF-B-AQ-22 10 707858 5617308 Creek Fm. Barren Unknown
C-305627 00-OF-B-SM-10 10 70282 1 5620530 I Barren Unknown APPENDIX C: CORAL IDENTIFICATION
Seven samples were sent to Dr. E.W. Bamber for coral macrofossil identification. All samples were from carbonate
rocks. The following table summarizes the report made on these samples (Bamber, 2002; report # 03-EWB-2002).
Table C-I
GSC Field number Zone Eaoting Northing Fauna number
solitary cyathopsid coral, indet. Early Carboniferous, C-305550 00-OF-B-HM-14 10 7031 31 5622246 ?Lithodrumus sp latest Visean ?Lithodrumus sp., ?Petalaxis sp., Early Carboniferous, C-305566 00-OF-B-WP-10 10 709730 5622950 immature lophophyllid? coral latest VisCan 2 Cystolonsdaleia stelcki (Nelson, mid-Carboniferous, C-305567 00-OF-B-WP-11 10 709839 5622899 1960)? possibly Serpukhovian Middle Visean to Early petalaxid? coral, indet Permian mid-Carboniferous, Cystolonsdaleia sp. cf. C. stelcki C-306318 00-OF-B-T2-WB-2 10 5617100 704550 probably (Nelson, 1960) Serpu k hovian. C-306319 00-OF-B-WB-3 10 5617400 707050 durhaminid coral, new genus Early Permian Petalaxis sp. cf. P. sutherlandi Early Permian, C-306320 00-OF-B-WB-4 10 56 17500 707200 Wilson, 1982, Lytvophyllum sp. Asselian indet., clisiophyllid solitary corals APPENDIX D: CONODONT PROCESSING AND IDENTIFICATION
Methodology
One-hundred and fifteen samples of carbonate rocks were collected and processed by the author for conodont microfossils. Processing was done in the micropaleontological lab of the Vancouver office of the Geological Survey of
Canada (GSC) under the supervision of Dr. Michael Orchard and at the micropaleontology lab at the University of Calgary under the supervision of Dr.
Charles Henderson. Samples with a University of Calgary Museum of
Paleontology (UCMP) number (Table D-1) were processed at the University of
Calgary. The methods described below are those used at the GSC laboratory.
The University of Calgary laboratory methods differ little from those of the GSC except that the samples are acidized twice for 3 days at a time, and the heavy liquid Tetrabromoethane is used.
Samples were crushed with a hammer into 1-3cm diameter-sized pieces and then weighed using a beam scale. The samples were then immersed in a solution of 10% glacial acetic acid in plastic buckets for the duration of seven days. The remaining insoluble portion was wet sieved in a twu-sieve stack to obtain a workable fraction (200 mesh portion); the coarse fraction (>I4 mesh sieve) was set aside to be weighed. The workable fraction was dried and then separated using the heavy liquid, Sodium Polytungstate, with a specific gravity of
2.85 g/cm3. The fraction of material heavier than 2.85 g/cm3was collected, (and, for samples processed at the University of Calgary, washed with acetone to remove the remaining Tetrabromoethane), and examined for conodonts.
Conodonts were recovered using a wet brush picking method and mounted on a specimen slide for examination. Conodonts were examined to determine genus and species as well as Conodont Alteration Index (CAI) value.
The following table (Table D-1) summarizes the processing records, CAI determinations, identification, and age determinations of the conodont microfossil samples collected for this study. Field GSC number Weight Weight Break-down UTM Eaating Northing Fauna CAI Age number (UCMP Zone in (9) out (g) number)
C-305700 01-OF-B-1 10 700709 5623434 Barren I I
Polygnathus vogesi, Polygnathus communis carina, Pseudopolygnathus early C-305701 01-OF-B-2 10 70071 1 5623435 fusiformis, Tournaisian Bispathodus stabilis, Siphonodella duplicata
C-305702 01-OF-B-5 10 700720 5623410 Barren I I
A Neostreptognathodus pequopensis, Mesogondolella n. sp. C-305703 01-OF-B-7 Artinskian 706904 7532 A, Diplognathodus augustus?, Hindeodus sp.
C-305704 01-OF-B-8 10 706808 5617614 Barren I I
Ordovician- rarniforrns - ' Triassic
c-305708 01-OF-B-21 10 707108 5618601 Barren 1 1 Field GSC number UTM Easting Northing Fauna CAI number (UCMP Zone number)
Pennsylvanian- C-305713 01-OF-6-27 10 706980 561 8183 Adetognathus sp. 2000 1691 Permian
Barren C-305715 01-OF-13-29 10 706972 561 7973 Sweetognathus spp. 5 - 6 Early Permian 1 1988 691 75 Early I Pennsylvanian C-305717 01-OF-B-31. 10 706819 561 7844 Adetognathus? 5-6 756 594 - Early Permian
------C-305719 01-OF-6-40 10 704090 5622018 Barren I I 1682 167 90 2 C-305720 01-OF-6-42 10 704374 5622291 Barren I 1 950 419 56
Barren
Ordovician- ramiforms 5 2248 507 Triassic
?Adetognathus sp., 6 ~enns~lvanian/21 92 1246 10 708664 5619758 Hindeodus sp. - Early
C-305727 01-OF-6-57 10 698483 561 9594 Barren I I
Ordovician- ramiforms 5 2039 1429 Triassic Field GSC number UTM Easting Northing Fauna CAI Age number (UCMP Zone number)
Gnathodus bilineatus, late Visean - Gnathodus 05730 01-OF-B-67 10 700402 56246 10 homopunctatus, 5 early Serpukhovian Lochreia commutata
Gnathodus bilineatus, late Visean - C-305731 01-OF-B-68 10 700679 5624860 Gnathodus girtyi, 5 early Cavusgnthus sp. Serpu khovian
C-305732 01 -OF-B-69 10 700758 5624908 Barren I I
C-305733 01-OF-B-75 10 701 199 5625400 Barren I I Ordovician- ramiforms 5 Triassic
- - Barren
0l-OF-B- late Carnian C-305738 85b 10 689166 5619483 Metapolygnathus - primitius - early Norian
Barren
Barren O1-OF-B- C-305743 10 689268 5624206 Meta~ol~gnat~us 4 - 5 late carnian nodosus Field GSC number uTM Easting Northing Fauna CAI Age number (UCMP Zone number)
10 694373 5625343 Hindeodus sp. 6 Probably Permian
ramiforms Ordovician- Triassic
OI-OF-B- C-305747 120 Barren
Palmetolepis minuta, OI-OF-B- C-305748 124 10 695097 5626163 Polygnathus early - Farnennian delicatula
Barren
Barren
01-0F-B- C-305757 62a 10 689830 5629500 Metapolygnathus 5 late Carnian nodosus
Barren
Barren
Barren
Field GSC number UTM Easting Northing Fauna CAI Age number (UCMP Zone number)
O1-OF-B- Pennsylvania1 C-305773 95b 10 691770 5628649 Neogondolella SP.? 4 - Triassic
0l-OF-B- C-305774 197 10 697121 5630812 Barren I I
Late 10 697283 5630675 Gnathodus bilineafus 5 ~i~~i~~i~~i~~
01-0F-B- C-305776 21 a 10 705374 5626269 Barren I I
Barren Ul (0 O1-OF-B- C-305778 223 10 708007 561 7248 Sweetognathus whitei 4 Artinskian
Epigondolella ex. gr. O1-OF-B- 4, late Norian C-305779 228 10 708895 5618564 biden tata, - altered Rhaetian Pan/igondolella sp. ?
01-0F-B- Cavusgnathus sp. C-305780 234 10 701531 5624375 indet. 5 Carboniferous
01-0F-B- C-305781 237 10 690760 5628202 Barren I I
01-0F-B- ?Metapolygnathus probably C-305783 239 10 689010 5629450 nodosus Carnian Field GSC number uTM Easting Northing number (UCMP Zone Fauna CAI Age number)
10 689805 5630351 Sweetognathus sP. 5 Early Permian
Ordovician- fragments - ' Triassic
Barren
Barren
01-OF-B- Neosteptognathodus C-305789 5.5 Artins kian 0 262 10 705430 5634503 pequopensis, o Sweetognathus sp.
OI-OF-B- 5.5 - C-305791 268 10 704345 5634650 ldio~rioniodusSP. Mississippian 6
Barren
O1-OF-B- C-305793 273b 10 704034 5632512 rounded indet 4 Ordovician- fragments Triassic
probably late Pennsylvanian 10 706691 5632300 Stre~tognathodusSP. 5 - Early Permian Field GSC number UTM Easting Northing Fauna CAI number (UCMP Zone number)
01-0F-B- C-305795 290a 10 710783 5628896 ramiforms 5 Permian
Barren
Barren
Barren
Late Pennsylvaniar Adetognathus sp?, 5 - - Early 11 289995 5634472 ?c,,usgn,thus 5.5 Permian; probably Earl) Permian
Barren
Barren
C-305807 01-0~-~-11 10 698783 561 9349 Barren I I .i v) v) ez g '%,.S% 92 2 'Om 2 g.a>Eoo~c- @ 0.2 bcQbD 0 Q m&50v)OC5 c o E~ss.9~ Q E yo " 8,. 4" .am Field GSC number UTM Easting Northing Fauna CAI Age number (UCMP Zone number)
OO-OF-B- C-305545 LO-4 (606- 10 702722 5622369 Barren I I 30) Gnathodus bilineatus, late Visean - OO-OF-B- Vogelgnathus C-305547 khl-04 (606- 10 7031 31 5622246 campbelli, 5 Serpu early khovian 39) Cavusgnathus na viculus?
2 0 00-OF-B- probably Late C-305552 RF-06b 10 703254 5623954 ldio~rioniodusSP. Mississippian
OO-OF-B- C-305557 GG-3 (606- 10 708067 5622025 Barren I I 3) Field GSC number UTM Easting Northing Fauna CAI Age number (UCMP Zone number)
OO-OF-B- K3Cl5559 GG-17 (606- 10 704432 5623393 ichthyoliths I I
34) 3
OO-OF-B- C-305560 GG-19 Barren
00-OF-B- probably Late C-305561 GG-19.5 10 704498 5623301 Cavu~gnathusSP. Mississippian
Neostreptognathodus OO-OF-B- sp., ~weetognathus C-305562 GG-26 5 Artinskian 10 706863 5621 124 whitei, A Diplognathodus sp. 0, P OO-OF-B- 05563 WP-6 (606- 10 709408 5623009 Barren I I 28)
Gnathodus bilneatus, Gnathodus homopunctatus, 00-OF-B- Gnathodus girtyi, early C-305564 WP-6g (606- 10 709408 5623009 Cavusgnathus sp., Serpukhovian 27) Lochreia commutata, Lochreia nodosa, Vogelgnathus campbelli st,ul 00 3 u Field GSC number UTM Easting Northing Fauna CAI Age number (UCMP Zone number)
Barren I I
00-OF-8- Sweetognathus K305582 U~-07(606- 10 708966 5618864 inomatus, 5'56 - Artinskian 9) Neogondolella sp.
Pennsylvania~ OO-OF-B- C-305584 UH-10 10 708962 561 8847 Neogondolella sp. 5 -probably ~riassic; Permian
Barren
Barren
Ordovician - 5 Triassic Field GSC number UTM Easting Northing Fauna CAI Age number (UCMP Zone number)
probably Mississippian
OO-OF-B- c-3&3593 ST-26 (606- 10 704605 561 7077 Barren I I 24)
00-OF-B- Gnathodus bilineatus, late Visean - c-3EE~94 EH-13 (606- 10 706670 561 9384 Cavusgnathus 5 early 25) naviculus? Serpukhovian
00-OF-B- Cavusgnathus late Visean 5 - C-305595 EH-21 (606- 10 707203 5619076 navicula, gnathodids - early 2 22) 55 Serpukhovian
OO-OF-B- C-305597 EH-26 (606- 10 707228 5619036 Sweetognathus sp. 5.5 Early Permian 24)
OO-OF-B- C-305598 SL-05 (606- 10 699262 5623798 Barren I I 37)
OO-OF-B- C-305599 SL-12 (606- 10 699909 5622870 Barren I I 2)