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Metallogeny of the Vancouver-Hope area, British Columbia Ditson, Gwendolen May 1978

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METALLOGENY OF THE VANCOUVER-HOPE AREA, BRITISH COLUMBIA  GWENDOLEN MAY DITSON B.S., U n i v e r s i t y of Southern C a l i f o r n i a , 1974  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Geological Sciences)  We accept t h i s thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA May, 1978 (c)  Gwendolen May Ditson, 1978  In presenting this thesis in partial  fulfilment of the requirements for  an advanced degree at the University of B r i t i s h Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this  thesis  for scholarly purposes may be granted by the Head of my Department or by his representatives.  It  is understood that copying or publication  of this thesis for financial gain shall not be allowed without my written permission.  Department of  G e o l o g i c a l Sciences  The University of B r i t i s h Columbia  2075 Wesbrook P l a c e Vancouver, Canada V5T 1W5  D a t e  May 24, 1978  ABSTRACT  The study area i s characterized by complex terrane encompassing the j u n c t i o n of three major t e c t o n i c b e l t s :  the Coast P l u t o n i c B e l t , the  Intermontane B e l t , and the Cascade B e l t .  Examination of the d e t a i l e d  t e c t o n i c framework was f a c i l i t a t e d by the construction of a time-space p l o t which i l l u s t r a t e s the s a l i e n t features of the s i x small-scale t e c t o n i c b e l t s w i t h i n the area.  Subsequent examination of metal deposits was f a c i l -  i t a t e d by the MINDEP inventory f i l e which supplied l o c a t i o n and reference information.  Detailed d e s c r i p t i v e information on metal deposits was  categorized and tabulated with respect to metals, deposit type, host rock formation and host rock type.  This data was then integrated i n t o the  t e c t o n i c framework to o u t l i n e a metallogenic model f o r the area. A s i m p l i s t i c model f o r the e v o l u t i o n of the major features i n the area involves eugeosynclinal and t r e n c h - l i k e d e p o s i t i o n from Upper Paleozoic u n t i l Jurassic-Cretaceous time when the developing Coast v o l c a n i c and p l u t o n i c arc c o l l i d e d with the established Intermontane arc on the east. Arc volcanism i n the Coast P l u t o n i c B e l t produced the i n i t i a l metal s u l f i d e accumulations  volcanogenic  i n the area which subsequently were remobilized  i n t o adjacent areas during c o l l i s i o n .  The axis of c o l l i s i o n contains a  major magmatic s u l f i d e deposit which probably formed at t h i s time as a r e s u l t of c o l l i s i o n .  S i g n i f i c a n t m i n e r a l i z a t i o n i s found also west of the  c o l l i s i o n a x i s near the deep-seated Hozameen f a u l t along which g o l d - r i c h f l u i d s have formed veins near serpentine bodies.  S i m i l a r l y , a large dissem-  inated gold deposit occurs i n s l a t e adjacent to the Hozameen f a u l t i n the area of major v e i n m i n e r a l i z a t i o n . Subduction responsible f o r the T e r t i a r y episode of plutonism and v o l canism centered i n the Cascade B e l t also produced small skarn, v e i n and  porphyry deposits during a subsequent episode of r e m o b i l i z a t i o n mineralization.  iv TABLE OF CONTENTS  ABSTRACT  i i  TABLE OF CONTENTS  iv  LIST OF TABLES  ix  LIST OF FIGURES  xi  ACKNOWLEDGEMENTS CHAPTER 1. INTRODUCTION  xiv 1  General Statement  1  D e f i n i t i o n of the Study Area  3  Methods  3  CHAPTER 2. GEOLOGY AND TECTONIC FRAMEWORK  5  Introduction  5  Time-Space P l o t  8  Eagle P l u t o n i c Belt  12  Units Within the Eagle P l u t o n i c B e l t  12  Deformation  13  Pasayten Fault  14  Ladner Trough  14  S t r a t i g r a p h i c Units  14  Deformation  16  Hozameen Fault  17  Hozameen Basin  18  Hozameen Group  18  Yale Intrusions  19  Deformation  19  Boundaries  19  V  Cascade B e l t  20  C-l:  C r y s t a l l i n e Core Rocks  22  C-2:  Shuksan Thrust Plate  24  C-3:  Western Flanking Units  26  C-4: Vedder Mountain Wedge  28  Spuzzum P l u t o n i c B e l t  29  Metamorphic Rocks  30  I n t r u s i v e Rocks  34  T e r t i a r y Volcanic Rocks  35  Coast P l u t o n i c B e l t Pendant Rocks  35 36  Older Units of Unknown Age  36  Harrison Lake Sequence  37  F i r e Lake and Gambier Groups; Pioneer Formation  39  P l u t o n i c Rocks  42  Post-Plutonic Rocks  43  Summary and Discussion  44  CHAPTER 3. METAL DEPOSITS  47  Introduction  47  Classification  51  Magmatic  51  Porphyry  51  Skarn  52  Volcanogenie  52  Vein  53  Shear  53  Disseminated and Massive  54  Major Mines and Related Occurrences  54  vi  Britannia  54  Geologic S e t t i n g and Early Interpretations  54  Current Interpretations  55  S u l f i d e Occurrences Outside the B r i t a n n i a Shear Zone  57  Northair  58  Description  58  Genesis  62  Other Deposits i n the Northair D i s t r i c t  64  Giant Mascot  64  Nature and O r i g i n of Ultramafic Rocks  66  Mineralization  66  Occurrences Outside the Giant Mascot Ultramafite  69  Mining Camps Without Major Mines  69  Eagle B e l t  71  Summit Camp  71  Jim K e l l y Creek Camp  74  Ladner Gold B e l t  76  23-Mile Camp  78  10-Mile Creek Camp  80  Harrison Lake D i s t r i c t  82  F i r e Lake Camp  84  P i t t Lake  84  Sechelt Peninsula  87  Isolated Past Producers and Important Prospects  87  Zel  87  Gem  89  Other Deposits  89  Summary  90  vii CHAPTER 4.  COMPUTER STUDY  93  Introduction  93  Metal and Deposit Type Abundances  97  Possible Ore Controls  100  Deposit Type  100  Tectonic B e l t  104  M i n e r a l i z a t i o n Characterizing Tectonic B e l t s  112  D i s t r i b u t i o n of Metals and Deposit Types Among Tectonic B e l t s Host Rock Formation  114 115  D i s t r i b u t i o n of Deposit Types and Metals Among Host Rock Formations M i n e r a l i z a t i o n Characterizing Host Rock Formations  117 121  Eagle P l u t o n i c B e l t  121  Ladner Trough  121  Hozameen Basin  123  Cascade Belt  123  Spuzzum P l u t o n i c B e l t  123  Coast P l u t o n i c B e l t  123  Host Rock Type  126  D i s t r i b u t i o n of Metals and Deposit Types Among Host Rock Types M i n e r a l i z a t i o n Characterizing Host Rock Types  127 130  I n t r u s i v e Rocks  130  Volcanic Rocks  132  Sedimentary Rocks  134  Deposit D i s t r i b u t i o n Maps  134  Summary  137  CHAPTER 5.  CONCLUSIONS AND METALLOGENY  139  viii REFERENCES CITED  143  APPENDIX A  149  APPENDIX B  156  ix LIST OF TABLES  2-1 2-2  2-3  Abbreviations used to i d e n t i f y u n i t s on the Geologic Map  6  B r i e f d e s c r i p t i o n s of u n i t s outside the study area which are shown on the Geologic Map (Figure 2-1) but not discussed i n the text  7  K/Ar radiometric determinations on p l u t o n i c rocks i n and near the study area  11  2- 4  Summary of tectonic h i s t o r y  45  3- 1  Producing deposits  48  3-2  Abbreviations and symbols used i n deposit d e s c r i p t i o n s  50  3-3  C h a r a c t e r i s t i c s of deposits i n the B r i t a n n i a D i s t r i c t  56  3-4  C h a r a c t e r i s t i c s of the Northair s u l f i d e bodies  61  3-5  C h a r a c t e r i s t i c s of deposits i n the Northair D i s t r i c t  65  3-6  C h a r a c t e r i s t i c s of deposits i n the Giant Mascot District  70  3-7  C h a r a c t e r i s t i c s of deposits i n the Eagle Complex  72  3-8  C h a r a c t e r i s t i c s of deposits i n the Summit Camp  3-9  C h a r a c t e r i s t i c s of deposits i n the Jim K e l l y Creek  73  Camp  75  3-10  C h a r a c t e r i s t i c s of deposits i n the Ladner Gold Belt  77  3-11  C h a r a c t e r i s t i c s of deposits i n the 23-Mile Camp  79  3-12  C h a r a c t e r i s t i c s of deposits i n the 10-Mile Creek Camp C h a r a c t e r i s t i c s of deposits i n the Harrison Lake  81  District  83  3-13  3-14  C h a r a c t e r i s t i c s of deposits i n the F i r e Lake Camp  85  3-15  C h a r a c t e r i s t i c s of deposits i n the P i t t Lake Area  86  3-16  C h a r a c t e r i s t i c s of deposits on the Sechelt Peninsula  86  3-17  C h a r a c t e r i s t i c s of i s o l a t e d producers and important occurrences  88  X  3- 18  Summary of metallogenic h i s t o r y  92  4- 1  Grade and tonnage of major deposits  95  4-2  Deposit status based on h i s t o r y of e x p l o r a t i o n , development or production  98  4-3  4-4  Comparison of Coast P l u t o n i c Belt d e n s i t i e s of the present study area and of the C o r d i l l e r a of B r i t i s h Columbia  106  Characterization of t e c t o n i c b e l t s  113  xi LIST OF FIGURES  1-1  Location of the study area r e l a t i v e to the t e c t o n i c b e l t s of the Canadian C o r d i l l e r a  1- 2  Location of metal deposits i n the Vancouver-Hope area  2- 1  Geology of the Vancouver-Hope area  (-pocket-)  2-la  Cross-section across the southeastern p o r t i o n of the study area; plutons have been removed to c l a r i f y p r e - i n t r u s i v e structures  (-pockete).  2-2  Time-space p l o t of the Vancouver-Hope area  2-3a  Location of K/Ar radiometric determinations on p l u t o n i c rocks i n and near the study area  2-3b  Location of K/Ar radiometric determinations from i n t r u s i v e rocks i n a p o r t i o n of the study area  2-4  Geologic map of the Skagit Region of Northern Cascades  2-5  Study areas of some p r i n c i p a l workers dealing with the metamorphic rocks of the Spuzzum P l u t o n i c Belt  2- 6  3- 1 3-2  \  10  Cpnn-k-p-t-) f^a-pGH^ Sr 31  A. P o s s i b l e subduction zones i n the Canadian C o r d i l l e r a ; l a t e r transcurrent motion suggests oblique subduction B. Method of a c c r e t i o n of c r u s t a l b l o c k s , r e s u l t i n g i n westward "jumping-out" of subduction zones  46  P r i n c i p a l areas of mineral occurrences, VancouverHope area  49  R e l a t i v e p o s i t i o n s pf the three main m i n e r a l i z e d . , zones and f a u l t s at N o r t h a i r Mines  3-3  Surface geology of the Giant Mascot U l t r a m a f i t e  3-4  D i s t r i b u t i o n of metal deposits on the time-space plot  3- 4a  Explanation of symbols on Figure 3-4  4- 1  Number of occurrences of each deposit type w i t h respect to c h a r a c t e r i s t i c metals  4-2  T o t a l number of occurrences of each metal  4-3  T o t a l number of occurrences of each deposit type  s-  60 67  (l>@ekat)7>?fl^ C4me  91 96 99 101  xii 4-4a 4-4b 4-5a  4-5b 4-6a  4-6b  4-7 4-8 4-9a 4-9b 4-10a  4-10b  4-11  4-12 4-13  Number of occurrences of copper, gold and s i l v e r w i t h ' respect to deposit type  102  Number of occurrences of molybdenum, z i n c , lead, i r o n and n i c k e l w i t h respect to deposit type  103  R e l a t i v e d e n s i t i e s of copper, molybdenum, gold, s i l v e r , lead and zinc w i t h respect to tectonic b e l t s and subdivisions  108  R e l a t i v e d e n s i t i e s of n i c k e l , i r o n , antimony and tungsten w i t h respect to t e c t o n i c b e l t s and subdivisions  109  R e l a t i v e d e n s i t i e s of magmatic, porphyry, skarn and volcanogenic deposits w i t h respect to t e c t o n i c b e l t s and subdivisions  110  R e l a t i v e d e n s i t i e s of v e i n , shear, disseminated and massive deposits w i t h respect to t e c t o n i c b e l t s and subdivisions  111  T o t a l number of occurrences i n each m i n e r a l i z e d geologic u n i t of the study area  116  Number of occurrences of each deposit type w i t h respect to host rock u n i t  118  Number of occurrences of copper, molybdenum, gold and s i l v e r w i t h respect to host rock u n i t  119  Number of occurrences of lead, z i n c , i r o n , antimony, tungsten and n i c k e l w i t h respect to host rock unit  120  Number of occurrences i n host rock u n i t s of the Eagle P l u t o n i c B e l t , Ladner Trough, Hozameen Basin and Cascade B e l t , w i t h respect to metal content and deposit type  122  Number of occurrences i n host rock u n i t s of the Coast P l u t o n i c Belt with respect to metal content and deposit type  124  Number of occurrences of each metal and deposit type with respect to i n t r u s i v e ( I ) , v o l c a n i c (V) and sedimentary (S) host rock types  128  T o t a l number of occurrences i n i n t r u s i v e , v o l c a n i c and sedimentary host rocks  129  Number of occurrences i n (a) intermediate to acid i n t r u s i v e rocks, (b) u l t r a m a f i c rocks, and (c) dikes, w i t h respect to metal content and deposit type  131  xiii 4-14  4-15  Number of occurrences In (a) basic v o l c a n i c rocks and greenstones, (b) acid v o l c a n i c rocks, (c) t u f f , agglomerate and v o l c a n i c breccia', and (d) u n c l a s s i f i e d and metamorphosed v o l c a n i c rocks, w i t h respect to metal content and deposit type  133  Number of occurrences i n (a) c l a s t i c sedimentary rocks, (b) limestone, and (c) s i l i c e o u s and unclass i f i e d sedimentary rocks, w i t h respect to metal content and deposit type  135  xiv ACKNOWLEDGEMENTS  I would l i k e to thank my advisor, Dr. A. J . S i n c l a i r , f o r suggestion of the t h e s i s t o p i c and c r i t i c a l review of the manuscript.  Dr. C. I .  Godwin and Dr. J . G. Payne thoroughly reviewed the manuscript and provided valuable c r i t i c i s m and encouragement.  Dr. R. L. Armstrong reviewed a por-  t i o n of the manuscript and provided valuable information concerning the t e c t o n i c elements of the Cascade B e l t . The B. C. M i n i s t r y of Mines and Petroleum Resources provided me with use of the a i r photo l i b r a r y , access to assessment r e p o r t s , and information which was graciously supplied by Judy Winsby and George James. I am g r a t e f u l to the MINDEP s t a f f f o r t h e i r cooperation and assistance. In p a r t i c u l a r , Jenny Stark a s s i s t e d i n the tedious chore of data  accumulation  at the outset of the study and accompanied me during f i e l d i n v e s t i g a t i o n s i n the summer of 1975. Lynn Gislason was an indispensable l i a s i o n between the computer and me; her s k i l l and patience were g r e a t l y appreciated. Several persons provided me w i t h information and access to properties which I v i s i t e d i n 1975; t h e i r generosity w i t h both t h e i r time and experience i s g r a t e f u l l y acknowledged.  S p e c i f i c a l l y , John Payne not only guided  me around a p o r t i o n of the B r i t a n n i a orebodies, but provided me w i t h a copy of the unpublished report regarding the volcanogenic origin- of B r i t a n n i a and a d d i t i o n a l unavailable information on the r e g i o n a l geology of the area. Peter Christopher and Plen Dickson k i n d l y guided me through underground workings at Giant Mascot and N o r t h a i r , r e s p e c t i v e l y . Funding was generously provided by Energy, Mines and Resources and the B r i t i s h Columbia M i n i s t r y of Mines and Petroleum Resources. I t i s not p o s s i b l e to thank i n d i v i d u a l l y a l l the persons i n the Department of Geological Sciences who supplied me w i t h moral support and  XV  encouragement.  Outstanding personal contributions toward the completion  of t h i s thesis were made by JoAnne Nelson, Lee Pigage and D i t a Runkle. Special thanks go to the departmental technicians f o r t h e i r s p o r t i v e encouragement and assistance.  1 1.  INTRODUCTION  GENERAL STATEMENT The o b j e c t i v e of t h i s study i s to define the metallogenic h i s t o r y of the southern end of the Coast P l u t o n i c Belt and adjacent areas which include the northern t i p of the Cascade B e l t and a small p o r t i o n of the southwestern edge of the Intermontane Belt (Figure 1-1).  Each of these major t e c t o n i c  b e l t s i s characterized by d i s t i n c t i v e g e o l o g i c a l features, but l o c a t i o n of boundaries between b e l t s i s d i f f i c u l t on the d e t a i l e d s c a l e of t h i s study. Metallogenesis i s approached from two viewpoints, f i r s t l y through desc r i p t i o n of important i n d i v i d u a l deposits and groups of deposits, and secondly through s t a t i s t i c a l compilations of s p e c i f i c c h a r a c t e r i s t i c s determined f o r every deposit f o r which published d e s c r i p t i v e information i s available.  The second approach enables deposits of a l l s i z e s to be consid-  ered i n order to obtain a more d e t a i l e d view of metal d i s t r i b u t i o n s , and i s based on the hypothesis that small occurrences should not be ignored i n an area where large deposits are rare.  Both these sections are preceded by a  d e t a i l e d examination of the geology and t e c t o n i c environment, presented on a geologic map, c r o s s - s e c t i o n and time-space, p l o t ( i n pocket).  The nature  of the time-space p l o t w i l l be discussed i n d e t a i l i n Chapter Two. A s i m i l a r study of the adjoining Taseko Lakes-Pemberton area to the north (Woodsworth, et_ a l . , 1977) suggested that abundant v e i n deposits along the eastern edge of the Coast P l u t o n i c Complex were formed by f l u i d s which might have o r i g i n a t e d i n p l u t o n i c rocks during c o o l i n g . However, such patterns are not r e a d i l y apparent i n the area considered here. Of secondary importance to t h i s study i s the evaluation of the MINDEP system as a q u a n t i t a t i v e approach to metallogenic s t u d i e s . D e t a i l s regarding the MINDEP system are discussed i n Chapter Four.  gure 1-1.  Location of the study area r e l a t i v e to the t e c t o n i c b e l t s of the Canadian C o r d i l l e r a ( a f t e r Sutherland Brown, et a l . , 1976).  3 DEFINITION OF THE STUDY AREA The boundaries of the study area enclose approximately 28,711 square kilometers, 18 percent covered by water and recent sediments.  The o r i g i n a l  boundaries at the outset of the study were contained w i t h i n NTS sheets 92-G and 92-H, West H a l f , but were subsequently modified f o r three reasons  (refer  to Figure 1-2 f o r d e f i n i t i o n of NTS boundaries): 1)  The northern boundary was extended to include the c l u s t e r of deposits southwest of Pemberton. One of these d e p o s i t s , N o r t h a i r , i s the only c u r r e n t l y producing deposit i n the study area.  2)  The southern p o r t i o n of the eastern boundary was extended to include an area which contains few metal d e p o s i t s , but whose geology i s valuable to an understanding of the t e c t o n i c h i s t o r y of the area.  3)  The e n t i r e eastern boundary was modified to extend only so f a r as the main area of outcrop of the N i c o l a and Kingsvale Groups. The N i c o l a Group contains a large number of metal deposits which probably are not r e l a t e d to the Coast P l u t o n i c Complex.  METHODS D e s c r i p t i v e information on metal deposits was gathered through an extensive l i t e r a t u r e search.  P r i n c i p a l sources of information include the  Annual Reports of the B r i t i s h Columbia M i n i s t e r of Mines, Geology, Exploration and Mining i n B r i t i s h Columbia, and Assessment Reports f o r the Vancouver and New Westminister Mining D i s t r i c t s . reports were made a v a i l a b l e to the author.  A few p r i v a t e company  F i e l d i n v e s t i g a t i o n s i n the  summer of 1975 served to f a m i l i a r i z e the author w i t h some of the deposits. Data were transferred onto coding forms and entered i n t o the MINDEP data bank f o r storage and l a t e r r e t r i e v a l .  Raw data output from t h i s data  bank was an i n v a l u a b l e t o o l to the compilation process. Deposits are i d e n t i f i e d with reference to the NTS sheet i n which they occur.  Since a l l sheets i n the study area are w i t h i n the 92 g r i d , t h i s  number has been dropped.  Therefore, the i d e n t i f i c a t i o n number of a deposit  i n the 92-H sheet, southwest quarter, w i l l be preceded by the l e t t e r s  HSW.  Figure 1-2 locates deposits i n the study area and the g r i d s i n which they occur.  5 2.  GEOLOGY AND TECTONIC FRAMEWORK  INTRODUCTION Figure 1-1 i l l u s t r a t e s the p o s i t i o n of the present study area r e l a t i v e to the s i x major s u b - p a r a l l e l b e l t s of the Canadian C o r d i l l e r a (Sutherland Brown, et a l . ,  1976).  The general geology of the area, shown i n Figure 2-1  (see a l s o Tables  2-1 and 2-2), has been compiled from numerous sources ( v i z . , Bostock,  1963;  Roddick, 1965; Monger, 1970; Rice, 1960; Woodsworth, 1977; Roddick and Hutchison, 1973; D u f f e l and McTaggart, 1952; Richards and McTaggart, 1976; and Roddick and O k u l i t c h , 1973).  Two-thirds of the area i s underlain by  i n t r u s i v e rocks, most belonging to the Coast P l u t o n i c Complex; sedimentary rocks dominate the southeastern s e c t i o n and occur w i t h v o l c a n i c rocks i n scattered remnants throughout the Coast P l u t o n i c B e l t .  A t r a n s i t i o n zone  between western p l u t o n i c and eastern sedimentary terranes i s characterized by metamorphic rocks of unknown age which merge i n t o the s t r u c t u r a l l y complex Cascades region to the south.  Transecting the study area are the  north-south-trending Fraser River F a u l t Zone''' and three other f a u l t s believed to have major h o r i z o n t a l and/or v e r t i c a l components. The author has divided the study area further i n t o s i x t e c t o n i c subd i v i s i o n s , which, from east to west, are the Eagle P l u t o n i c B e l t , the Ladner Trough, the Hozameen Basin, the Cascade B e l t , the Spuzzum P l u t o n i c B e l t and the Coast P l u t o n i c B e l t .  The Cascade B e l t , due to i t s complexity, has  been subdivided further i n t o four b e l t s , r e f e r r e d to as C - l , C-2, C-3  and  C-4. The time-space p l o t (Figure 2-2; described below) has used these t e c t o n i c d i v i s i o n s to present data not evident on the geologic map also r e f e r r e d to herein as the S t r a i g h t Creek Fault Zone  (Figure  6  TABLE 2-1.  I.  II.  Eagle P l u t o n i c Belt  Coast P l u t o n i c B e l t  CQ N  AP av BH BI  Coast P l u t o n i c Complex Hozameen Group Quaternary sediments  Cascade B e l t C CH CK CR D NK •Qs SK YA  V.  Coquihalla Group Coast P l u t o n i c Complex Dewdney Creek Group Jackass Mountain Group Ladner Group Pasayten Group  Hozameen Basin CR HZ Qs  IV.  Coquihalla Group N i c o l a Group  Ladner Trough CQ CR DC JM L P  III.  Abbreviations used to i d e n t i f y u n i t s on the Geologic Map (Figure 2-1). Units are arranged a l p h a b e t i c a l l y w i t h i n tectonic b e l t s ; see text f o r descriptions and ages.  Cultus Formation C h i l l i w a c k Group Chuckanut Formation Coast P l u t o n i c Complex Darrington P h y l l i t e Nooksack Group Quaternary sediments Skagit Formation Yellow Aster C r y s t a l l i n e Complex  Spuzzum P l u t o n i c B e l t av CR gn ms Qs SS  acid v o l c a n i c rocks Coast P l u t o n i c Complex gneiss metasedimentary rocks Quaternary sediments S e t t l e r Schist  Agassiz P r a i r i e Formation a c i d v o l c a n i c rocks Brokenback H i l l Formation Bowen Island Group B i l l h o o k Creek Formation Mysterious Creek Formation Echo Island Formation basic v o l c a n i c rocks fCheakamus Formation < Empetrum Formation (.Helm Formation Coast P l u t o n i c Complex F i r e Lake Group Gambier Group G a r i b a l d i Group gneiss Harrison Lake Formation Kent Formation metamorphic rocks metasedimentary rocks Pioneer Formation Peninsula Formation Quaternary sediments sedimentary rocks Twin Islands Group  {  bv CEH  CR FL G GB gn HL K m ms PI PN Qs s TI  TABLE 2-2.  Symbol  Brief"descriptions of units outside the study area which are shown on the Geologic Map (Figure 2-1) but not discussed in the text. Where possible, information was updated from Roddick and Okulitch, (1973).  N a m e  Description  Age  Reference  abv  plateau basalt and dacite flows; may be equivalent to Garibaldi Group  late Miocene or Pliocene  Roddick and Hutchison, 1973  bv-1  andesite; minor amounts of dacite  lower Tertiary  Roddick and Hutchison, 1973  bv-2  valley and plateau basalt  late or post-Miocene  Rice, 1960  C W  Coldwater Beds  sandstone, shale, conglomerate; coal seams  Eocene  Duffel and McTaggart, 1952  HU  Hurley Formation  argillite, limestone, tuff, conglomerate, andesite flows  Upper Triassic  Roddick and Hutchison, 1973  KL  Kamloops Group  basalt and dacite  Eocene and Oligocene  Duffel and McTaggart, 1952  KVs  Kingsvale Group; sedimentary rocks  arkose, conglomerate, greywacke  Upper Cretaceous  Rice, 1960  KVv  Kingsvale Group; volcanic rocks  basalt and andesite lavas; agglomerate, tuff, breccia  Upper Cretaceous  Rice, 1960  PRs  Princeton Group; sedimentary rocks  basin conglomerate, sandstone and shale  Eocene  Rice, 1960  PRv  Princeton Group; volcanic rocks  basalt, andesite and dacite lavas  Eocene  Rice, 1960  sedimentary and volcanic rocks  mid-Eocene  Duffel and McTaggart, 1952  s,bv SB  Spences Bridge Group  andesite and dacite lava and Lower Cretaceous pyroclastic rocks; minor amounts of basalt and rhyolite \  Rice, 1960  8 2-1).  Both the geologic map and the time-space p l o t should be constantly  referred to as i l l u s t r a t i o n s of events and r e l a t i o n s h i p s discussed throughout the t e x t .  TIME-SPACE PLOT The time-space p l o t (Figure 2-2) i s designed to diagrammatically i l l u s t r a t e events occurring i n a p a r t i c u l a r area at a p a r t i c u l a r time i n order to c l a r i f y cause/effect r e l a t i o n s h i p s which are d i f f i c u l t to portray 2 on geologic maps or cross-sections.  Events represented on the p l o t  include: 1) 2)  Deposition I n t r u s i o n (K/Ar dates are p l o t t e d as minimum ages; l o c a t i o n and source of these dates are shown i n Figures 2-3a,b and Table 2-3)  3)  F a u l t i n g ( f a u l t movement i s depicted along corresponding b e l t d i v i s i o n s or i n the affected b e l t i n an approximate east-west p o s i t i o n according to units affected)  4)  Folding  5)  Deformation (period of f o l d i n g , f a u l t i n g and metamorphism which generally masks the o r i g i n a l character of rocks)  (without s i g n i f i c a n t metamorphism)  A v e r t i c a l time axis i s presented to scale (except where noted) and i s divided according to Van Eysinga, 1975. The h o r i z o n t a l distance  axis  consists of two schematic northeast-southwest transects o f f s e t i n a northsouth d i r e c t i o n between the Spuzzum P l u t o n i c Belt and the Cascade B e l t . Distance i s not to scale i n order to accommodate events i n the very narrow belts. Important aspects which cannot be portrayed on a time-space p l o t include the f o l l o w i n g : 1) True s t r a t i g r a p h i c thicknesses are not shown i n order to i l l u s t r a t e the a c t u a l or possible duration of deposition or formation of a u n i t . G r i f f i t h s (1977) discusses the construction and a p p l i c a t i o n of time-space plots i n d e t a i l .  Figure 2-3a.  L o c a t i o n of K/Ar r a d i o m e t r i c determinations on p l u t o n i c rocks i n and near the study area. Refer to Table 2-3 f o r b r i e f sample d e s c r i p t i o n s and sources of information.  10  f  I  )  •  Giant Mascot j \  \ Liltramattc Body. „. „  ,  i M t H ,8S.iJ  ,. Barr \ tatholiiVt  K  i  ' . Y a l e \Int.\  I  '  ^ .28fll\  10  kilometers  ^/ CkilLick\ \ BatUilk  j  Canada " " U.S.A. Figure 2-3b.  Location of K/Ar radiometric determinations from i n t r u s i v e rocks i n a p o r t i o n of the study area ( a f t e r Richards and McTaggart, 1976, and McLeod, e t a l . , 1976).  TABLE 2-3.  FIGURE 2-3a,b FOR LOCATIONS. K / A r RADIOMETRIC DETERMINATIONS ON PLUTONIC ROCKS IN AND NEAR THE STUDY AREA; SEE  Idrntlflcatlon  (Mi)  Numh/T  Pluton(a)  Rock Type  M n t c r l n l Analysed  ARC  CSC 62-56  E a g l e Complex  Granodiorite  Blotlte  143  Needle Peak  Granite  Blotlte  39  CSC 65-9  E a g l e Complex  Cranodlortte  Blotlte  98-6  CSC  65-10  p l u t o n on Hozameen F a u l t  Granodiorite  Blotlte  84-6  CSC  72-3  H e l l ' s Cate  Quartz D l o r l t e  Hornblende  40-4  CSC  72-4  He 11'a C a t e  Quartz D l o r l t e  Blotlte  44-3  CSC  65-8  Rc f c r c n c c L e e c h , e£ a l _ . , 1963  4  +  1967  Wanless, e t . d . ,  1973  "  CSC  72-5  Scuzzy  Quartz D l o r l t e  Blotlte  70-4  CSC  72-6  SpuzEum  Quartz D l o r l t e  Hornblende  73  CSC  72-7  Spuzzum  Quartz D l o r l t e  Blotlte  74-4  CSC  72-8  Scuzzy  Quartz D l o r l t e  HornHlende  72 i 4  t  W a n l e s s , ct a K ,  4  W a n l e s s , et_ a l . , 1977  CSC 76-32  Coast P l u t o n i i  Complex  Granodiorite  Blotlte  113 - 4  CSC  76-33  C o a s t P l u t o n i c Complex  Granodiorite  Hornblende  119 - 5  CSC 76-46  C o a s t P l u t o n i c Complex  Granodiorite  Blotlte  88.6 - 3.3  V  CSC 76-47  C o a s t P l u t o n i c Complex  Granodiorite  Hornblende  97.5 - 4.5  II  126  Coast P l u t o n i c Complex  Granodiorite  Blotlte  99,95  AK 24  H e l l ' s Gate  Granodiorite  Blotlte  35  AK 31  Mt. B a r r  Quartz D l o r l t e  Blotlte  18  43  Mt. B a r r  Quartz D l o r l t e  Blotlte  18  Spuzzum  Quartz D l o r l t e  Blotlte  103  KA  AK  la  B a a d s g a a r d , e ^ a l _ . , 1961  i5  lb  Spuzzum  Quartz D l o r l t e  Blotlte  103*  2a  Spuzzum  Quartz D l o r l t e  BlotIte  79  2b  Spuzzum  Quartz D l o r l t e  Hornblende  81 + 4  3  Spuzzum  Quartz D l o r l t e  Blotlte  83 + 4  4a  Yale  Granodiorite  Blotlte  59  4b  Yale  Granodiorite  Biotite  59 - 3  7  Yale  Quartz Monzonite  Blotlte  41 + 2  9  S l i v e r Creek S t o c k  Quartz D l o r l t e  Hornb lende  35 i 2  10  Chllllwack  Gabbro  Biotite  29  t  1  11  Chllllwack  Quartz D l o r l t e  Biotite  28  Z  1  12  Chllllwack  Quartz  Blotlte  26  r I.  1  Monzonite  5  t  4  i3  13  Chllllwack  Quartz  Monzonite  Blotlte  26 i 1  14  Chllllwack  Quartz Monzonite  Blotlte  26  t  1  16a  Mt. B a r r  Quartz D l o r l t e  Biotite  '24  t  1  16b  Mt. B a r r  Quartz D l o r l t e  Biotite  24  i1  17  Mt. B a r r  Granodiorite  Biotite  21  t  1  t  1  i  1  1  R i c h a r d s and W h i t e ,  "  R l c h a r d a and M c T a g g a r t , 1976 R i c h a r d s and W h i t e ,  „  it  18  Ht. B a r r  Quartz  Dlorlte'  Biotite  19  Mt. B a r r  Quartz  Monzonite  Biotite  16  Spuzzum  Dlorlte  Hornblende  89 - 2.8  JHc 1  G i a n t Mascot U l t r a m a f l t e  Hornblendi'te  Hornblende  95  JMc 2  Giant Mascot U l t r a m a f l t e  Hornblende  whole  JHc 3  G i a n t Mascot U l t r a m a f l t e  Homblendlte  Hornblende  104 - 4  JMc 4  GiaBt Mascot U l t r a m a f l t e  Hornblendlte  Hornblende  108 - 4  JMc 5  Spuzzum  Dlorlte  Hornblende  JHc 6a  Spuzzum  Tonalite  Blotlte  79.4 - 2.5  JHc 6b  Spuzzum  Tonalite  Hornblende  85.1 -  JH  Spuzzum  482-1  C o a s t P l u t o n i c Complex  Quartz D l o r l t e  Hornblende  77.5  482-2  C o a s t P l u t o n i c Complex  Quartz D l o r l t e  Blotlte  70.2  482-3  C o a s t P l u t o n i c Complex  Granodiorite  Hornblende  16.9  482-4  Const P l u t o n i c Complex  Granodiorite  Blotlte  84  "  482-5  C o a s t P l u t o n i c Complex  Granodiorite  Hornblende  75  "  482-6  C o a s t P l u t o n i c Complex  Dlorlte  Hornblende  51.6  CB-1  C o a s t P l u t o n i c Complex  Blotlte  158  CB-2  C o n s t P l u t o n i c Complex  Blotlte  95  C.B-3  C o a s t P l u t o n i c Complex  Hornblende  97  GB-4  C o a s t P l u t o n i c Complex  Blotlte  93  CB-5  Const P l u t o n i c Complex  Amphlbole  97  CB-6  Const P l u t o n i c Complex  Blotlte  90  GB-7  C o a s t P l u t o n i c Complex  Granodiorite  Blotlte  94  CM-1  C o a s t P l u t o n i c Complex  Quartz D l o r l t e  Hornblende  GM-2  C o a s t P l u t o n i c Complex  Quartz D l o r l t e  Blotlte  157  M-19  C o a s t P l u t o n i c Complex  Dlorlte  Hornblende  117 - 4  M-21  C o a s t P l u t o n i c Complex  Cranodlorlte  Biotite  113-3  FT-1  C o a s t P l u t o n i c Complex  whole rock  91  FT-2  C o a s t P l u t o n i c Complex  Hornblende  103  Pyroxenlte  t  4  and  pyroxene  description revised by Richards and McTaggart, 1976  McLeod, et_ a l . , 1976  "  89.6 - 3.1  "  2.8 Monger, 1970  76  ''  R l c h a r d a and M c T a g g a r t , 1976  •i  119*4  rock  Woodsworth, 1977  tl  White,  1968  Mathews,  148 - 5  i5  1970  II  18  8H  1970  it  McKlllop,  1968 1973  " Caron,  1974  R o d d i c k , e t a l _ . , 1977 ii  12  2)  Displacements along major f a u l t s cannot be shown, but time and place of major f a u l t i n g and u n i t s a f f e c t e d by f a u l t i n g are shown. Major h o r i z o n t a l movement might have juxtaposed u n i t s that o r i g i n a l l y were not side-by-side.  3)  Relationships between u n i t s which are not conformable are not represented. Gaps between u n i t s i n the same s t r u c t u r a l b e l t might represent d i s c o n f o r m i t i e s , angular unconformities, or the u n i t s might not be i n contact with each other, but but s p a t i a l l y separated w i t h i n the same b e l t .  EAGLE PLUTONIC BELT Units Within the Eagle P l u t o n i c B e l t Schistose basic v o l c a n i c rocks of the N i c o l a Group (N), g r a n o d i o r i t e , t o n a l i t e and gneiss of the Eagle Complex, and a c i d extrusions of the Coquihalla Group (CQ) are the main l i t h o l o g i c u n i t s i n the Eagle P l u t o n i c Belt.  Of these three u n i t s , the Eagle Complex i s by f a r the most widespread. N i c o l a greenstones are part of a large area of diverse submarine flows,  flow breccias and shaley to limy sedimentary rocks east of the study area, but they occur i n t e r m i t t e n t l y i n the study area only w i t h i n and around the borders of the Eagle Complex.  F o s s i l s i n the N i c o l a Group outside the study  area are Upper T r i a s s i c (Rice, 1960). Coarse-grained, n o r t h w e s t e r l y - f o l i a t e d granodiorite and t o n a l i t e (apparently of i n t r u s i v e o r i g i n ) make up the majority of the Eagle Complex, but pegmatite, gneiss and migmatite are common. Age c o n s t r a i n t s place i n t r u s i o n between extrusion of Late T r i a s s i c N i c o l a Group, which i s intruded 3  and metamorphosed by the Eagle Complex (Cairnes, 1924),  and deposition of  A l b i a n (uppermost Lower Cretaceous) Jackass Mountain conglomerates to the west, which contain cobbles of Eagle (?) granodiorite (Coates, 1974).  Two  samples of f o l i a t e d granodiorite along the Hope-Princeton highway have 3  An a l t e r n a t e hypothesis i s that of Anderson (1971), who believes i n t r u s i v e rocks of the Eagle Complex were derived from the N i c o l a Group by anatectic melting. Metamorphic e f f e c t s s p a t i a l l y associated with the Eagle/Nicola contact are i n t e r p r e t e d by Anderson as e f f e c t s of thermal gradients responsible f o r the formation of the Eagle Complex, not products of i n t r u s i o n .  y i e l d e d K/Ar model ages of 148 Ma (Leech, et a l . , 1963) and 98 Ma et a l . ,  (Wanless,  1967).  Subaerial Coquihalla v o l c a n i c rocks were deposited on an u p l i f t e d and eroded surface of granodiorite (Cairnes, 1924), and onto sedimentary rocks west of the g r a n o d i o r i t e , thereby covering the f a u l t which forms the western boundary of the Eagle P l u t o n i c B e l t . communication,  R. G. Berman  (personal  1978) recognizes a 4,000-foot s e c t i o n of r h y o l i t i c flows and  p y r o c l a s t i c rocks intruded by a n d e s i t i c to d a c i t i c bodies.  These s t r a t i f i e d  v o l c a n i c rocks are intruded by a massive d i o r i t i c plug which i s probably a l a t e i n t r u s i v e phase of the Coquihalla Group (Cairnes, 1924).  E x t r u s i o n of  the Coquihalla Group i s bracketed by three K/Ar determinations on d a c i t e / andesite, r h y o l i t e and d i o r i t e which y i e l d e d dates of 19.5+0.9, 20.9+0.7, and 22.1 + 0.8 Ma, r e s p e c t i v e l y (R. G. Berman, personal communication,  1978).  Deformation Monger (1970) states that the Eagle Complex, although f o l i a t e d , was not affected by major mid-Cretaceous rocks f a r t h e r west.  compressive deformation evident i n  However, mid-Cretaceous u p l i f t of the Eagle Complex d i d  occur along the Pasayten Fault.  Large f a u l t s and f o l d s i n the Eagle Complex  were not recognized by S t a a t z , et a l . , (1971) i n studies south of the border; they concluded that mid-Cretaceous  deformation d i d not extend east of the  Pasayten F a u l t . On the other hand, Anderson (1971) described folded  metasedimentary  gneisses of the Eagle Complex which have "undergone the same deformational event" as rocks West of the Pasayten F a u l t , while more competent t o n a l i t e does not e x h i b i t f o l d i n g .  The 98 Ma date (Wanless, et a l . , 1967) i s also a  c o n t r a d i c t i o n to the supposed lack of mid-Cretaceous  deformation.  However,  i f the Eagle Complex was unroofed and supplying sediment to a westerly basin i n A l b i a n time (108-100 Ma), the s i g n i f i c a n c e of the 98 Ma radiometric date  14 i s not c l e a r . I f Monger and S t a a t z , et a l . , were f a m i l i a r only w i t h g r a n o d i o r i t e and t o n a l i t e of the Eagle Complex, deformation recognized by Anderson has yet to be examined adequately.  C e r t a i n l y the contradictions are i n d i c a t i v e of  a poor understanding of the character and h i s t o r y of the Eagle Complex. Pasayten Fault Considerable v e r t i c a l and r i g h t - l a t e r a l movement i s assumed to have occurred along the steep westerly-dipping Pasayten Fault which forms the western boundary of the Eagle P l u t o n i c Belt (Coates, 1974).  Movement along  the f a u l t produced c a t a c l a s t i c textures and increased i n t e n s i t y of f o l i a t i o n near the f a u l t i n rocks of the Eagle Complex.  Small, u n f o l i a t e d plugs near  the f a u l t have been dated at 94 Ma (Staatz, et a l . , 1971).  On the assump-  t i o n that these plugs, i f present, would have been affected by movement of the Pasayten F a u l t , Staatz, et^ a l . , placed an upper l i m i t of 94 Ma on f a u l t movement.  Rocks east of the Pasayten Fault are believed by Coates (1974)  to be the source of Lower Cretaceous arkosic sediments i n the trough west of the f a u l t , thus f a u l t movement could have occurred as early as lowermost Cretaceous.  LADNER TROUGH The fault-bounded Ladner Trough records a long h i s t o r y of sedimentation which i s important i n determining the timing of u p l i f t of adjacent areas. Detailed studies by Coates (1974) provide most of the data discussed below. S t r a t i g r a p h i c Units F o s s i l evidence i n d i c a t e s that d e p o s i t i o n of the s l a t y J u r a s s i c Ladner Group (L) might have begun as early as Sinemurian, and continued through mid-Bajocian.  Deposition occurred along a basin which was open to the west  15  and r e c e i v i n g sediment from an e a s t e r l y v o l c a n i c highland (probably N i c o l a ) . Sediments forming the eastern and western portions of the basin represent two d i f f e r e n t environments of sedimentation: eastern shallow-water to suba e r i a l , coarse-grained v o l c a n i c sediments w i t h minor amounts of fine-grained marine t u r b i d i t e s and a n d e s i t i c flows contrast with western deep-water pelagic sediments and t u r b i d i t e s .  Easterly-derived a r k o s i c sandstones  toward the top of the western sequence i n d i c a t e shallowing i n Bajocian time. The Upper J u r a s s i c Dewdney Creek Group (DC) l i e s disconformably or with s l i g h t angular unconformity above the western part of the Ladner Group. Shallow-water marine sediments c o n s i s t i n g of v o l c a n i c sandstone and sandy a r g i l l i t e were derived from an e a s t e r l y v o l c a n i c source. Minor amounts of g r a n i t i c d e t r i t u s appear i n conglomerates near the base of the sequence. Minor a l l u v i a l sedimentation and volcanism was reported by Coates to have occurred between deposition of Dewdney Creek and Jackass Mountain Groups, but due to f a c t o r s such as rare and indeterminate f o s s i l s , f a u l t e d contacts, and the r e s t r i c t e d extent of these u n i t s , they are not discussed further. Mixed marine and non-marine conglomerates and sandstones (Hauterivian to mid-Albian) of the Jackass Mountain Group (JM) l i e disconformably above the Dewdney Creek Group.  The northern s e c t i o n i s described by Monger (1970)  as dark, massive greywacke and interbedded conglomerate which may be p a r t l y non-marine.  Coates described the southern sections as shallow marine sand-  stones and conglomerates w i t h l o c a l stagnant and non-marine portions. Throughout most of the sequence an e a s t e r l y source i s indicated by increasing grain s i z e toward the east.  I n a d d i t i o n , recognizeable d e t r i t u s from Eagle  and N i c o l a terranes was noted by Coates.  Conglomerates record a sudden  u p l i f t to the east i n e a r l y A l b i a n time ( i . e . , movement along the Pasayten F a u l t ) ; westerly-derived sediments become evident near the top of the  16  Jackass Mountain Group. Non-marine Aptian-Albian Pasayten Group (P) conglomerate, sandstone and p e l i t e o v e r l i e and i n t e r f i n g e r with dominantly marine Jackass Mountain Group rocks to the east.  A sudden change to a high energy environment  occurred i n A l b i a n time, recorded by deposition of red beds, poorly sorted conglomerates and fanglomerates. Coates believed A l b i a n sediments i n d i c a t e both a westerly volcanic-sedimentary provenance and an e a s t e r l y p l u t o n i c metamorphic provenance; increasing proportions of westerly-derived sediments occur toward the top of the s e c t i o n . Other u n i t s of minor importance i n the Ladner Trough are v o l c a n i c rocks of the Coquihalla Group, Needle Peak pluton, and a small region of N i c o l a (?) v o l c a n i c rocks (Figure 2-1) along the Pasayten F a u l t .  The southern area  designated as Coquihalla v o l c a n i c rocks i s not correlated d e f i n i t e l y with the Coquihalla Group; i t unconformably o v e r l i e s Lower Cretaceous sedimentary rocks and the Chuwanten Fault (see below), suggesting a T e r t i a r y age. Needle Peak pluton i s a discordant i n t r u s i o n of coarse granite and granod i o r i t e which has been dated at 39 Ma (Wanless, et_ a l . , 1967).  Not much i s  known of the small area of rocks which Rice (1960) mapped as N i c o l a Group, as he does not describe the occurrence i n d e t a i l .  I t i s p o s s i b l e that t h i s  occurrence does not belong to the N i c o l a Group, as i t i s on the western ("wrong") side of the Pasayten F a u l t , but i t remains as N i c o l a i n t h i s study f o r lack of contrary evidence. Metamorphism of rocks of the Ladner Trough i s s l i g h t , being confined to z e o l i t e or lowermost greenschist f a c i e s . Deformation The Chuwanten Fault i s an imbricate southwesterly-dipping thrust zone which probably i s r e l a t e d g e n e t i c a l l y to major f l e x u r a l - s l i p f o l d i n g during Late Cretaceous compression.  South of the border, Tabor, et a l . , (1968)  report an 86 Ma dike o f f s e t by the Chuwanten F a u l t , i n d i c a t i n g i n i t i a t i o n or renewal of movement a f t e r t h i s time.  F o l d i n g , however, may have begun  as early as Cenomanian, as the Upper A l b i a n Pasayten and Jackass Mountain Groups are the youngest u n i t s involved.  An upper l i m i t f o r both f o l d i n g  and f a u l t i n g i s u n c e r t a i n , but placed as lowermost T e r t i a r y , since the Straight Creek Fault Zone truncates deformed A l b i a n sedimentary rocks.  A  r e a l upper l i m i t i s defined by the Eocene Needle Peak pluton which c l e a r l y 4 post-dates major s t r u c t u r e s . Hozameen Fault Just as the Pasayten Fault forms the eastern edge of the Ladner Trough, so the western edge i s defined by the Hozameen F a u l t . break with probably mantle-derived, (Misch, 1966)  A major c r u s t a l  tectonically-emplaced  serpentine  along i t s t r a c e , exposures of the Hozameen Fault are v e r t i c a l  to steeply westerly-dipping over thousands of v e r t i c a l feet i n some places (Staatz, et a l . , 1971), but f l a t t e n south of the United States-Canada border to blend with the e a s t e r l y - d i r e c t e d Jack Mountain Thrust Prong ( c f . Figure 2-4).  Considerable  v e r t i c a l movement i s presumed to have occurred, with the  west side moving up r e l a t i v e to the east s i d e . Movement along the Hozameen Fault i s r e l a t e d to major mid- to Late Cretaceous deformation i n v o l v i n g Ladner Trough sedimentary rocks.  Timing  of the onset of movement i s not known, but i s probably recorded by westerlyderived, high-energy Pasayten sediments i n A l b i a n time. the trace of the f a u l t (Coates, i n Wanless, et a l . , 1967)  An 84 Ma pluton on gives an upper  l i m i t to f a u l t movement. _  —  The upper l i m i t proposed by Coates i s 84 Ma, the age of a small pluton that intrudes Ladner s l a t e s along the western boundary of the area. Although t h i s pluton might c l e a r l y post-date s t r u c t u r e s here, i t does not n e c e s s a r i l y post-date structures i n the r e s t of the b e l t , and i t contradicts the e v i dence f o r l a t e r (post-86 Ma) movement along the Chuwanten F a u l t .  18  This upper l i m i t f o r the Hozameen Fault roughly coincides w i t h the onset of movement along the Chuwanten F a u l t , perhaps i n d i c a t i n g that e a s t e r l y - d i r e c t e d compression (with consequent deformation and thrusting) was a pattern that p e r s i s t e d throughout Upper Cretaceous time, but the locus of t h r u s t i n g s h i f t e d to the east i n mid-Upper Cretaceous. The Hozameen F a u l t i s truncated to the north along the Fraser River where the Straight Creek and Fraser River Fault Zones merge to form the eastern boundary of the Ladner Trough.  The S t r a i g h t Creek F a u l t , discussed  i n d e t a i l below, i s an important feature of the Cascade B e l t .  HOZAMEEN BASIN Hozameen Group The Hozameen Group (HZ) was formed i n an oceanic basin i n which chert, v o l c a n i c rocks, and limestone were deposited along w i t h f i n e p e l i t i c rocks. Ribboned chert, generally associated w i t h p e l i t e , i s abundant.  Limestone  lenses are r a r e , and most commonly are associated w i t h b a s a l t i c , l o c a l l y pillowed greenstone.  A paleogeographic  r e c o n s t r u c t i o n depicts a deep marine  basin with v o l c a n i c i s l a n d s and associated a t o l l s (Monger, 1977). Absence of f o s s i l s , and contacts which are e i t h e r t e c t o n i c or with Upper Cretaceous or younger u n i t s or w i t h metamorphic u n i t s , have obscured the age of the Hozameen Group.  A Pennsylvanian-Permian age has been  assigned t e n t a t i v e l y based on l i t h o l o g i c s i m i l a r i t i e s w i t h the Cache Creek Group (Monger, 1970); Lower to Middle T r i a s s i c has also been assigned on s i m i l a r grounds w i t h the Fergusson Group (Cameron and Monger, 1971). Lowermost greenschist f a c i e s r e g i o n a l metamorphism affected most of the Hozameen Group; metamorphic grade increases toward the western contact where almandine amphibolite grade rocks of the Hozameen Group appear to blend w i t h the Custer Gneiss u n i t of that grade.  19 Yale Intrusions The f o l i a t e d stocks, s i l l s and dikes which intrude the western edge of the Hozameen Group are r e f e r r e d to as the Yale i n t r u s i o n s (McTaggart and Thompson, 1967). most common.  Rock types vary considerably, but b i o t i t e g r a n o d i o r i t e i s  A l l types e x h i b i t some degree of c a t a c l a s i s , with sheared,  mylonitized and g n e i s s i c v a r i e t i e s common. p a r a l l e l those i n adjacent country rocks.  Planar s t r u c t u r e s i n i n t r u s i o n s The Paleocene to Eocene age of  the Yale i n t r u s i o n s i s based on i n c l u s i o n s of S e t t l e r S c h i s t , Hozameen Group, Custer Gneiss and Spuzzum i n t r u s i o n s , i n t r u s i o n by the C h i l l i w a c k B a t h o l i t h , and radiometric dates of 59 and 41 Ma (Richards and McTaggart, 1976). Deformation Deformational h i s t o r y of the Hozameen Basin i s summarized as f o l l o w s : 1)  P r e - J u r a s s i c development of northwesterly-trending f o l d s and f a u l t s (McTaggart and Thompson, 1967; Monger, 1970).  2)  Minor n o r t h e a s t e r l y - t r e n d i n g f o l d i n g and deformation associated with u p l i f t along the Hozameen Fault during mid-Cretaceous.  3)  Northwesterly f o l d i n g i n the southern p o r t i o n r e l a t e d to Late Cretaceous Ladner Trough deformation (Monger, 1970).  4)  Eocene shearing of the Yale i n t r u s i o n s , probably synchronous with major f a u l t i n g along the Fraser River and S t r a i g h t Creek Fault Zones (McTaggart and Thompson, 1967). Folding associated with these f a u l t zones i s of l o c a l s i g n i f i c a n c e , and therefore not represented on the time-space p l o t .  Boundaries The western boundary of the Hozameen Basin i s defined by the gradational metamorphic contact between Hozameen Group greenstones and amphibolite f a c i e s Custer Gneiss i n the southern and c e n t r a l p o r t i o n s , and by the S t r a i g h t Creek Fault Zone i n the northernmost p o r t i o n of the area.  Neither the Hozameen  Group nor the Yale i n t r u s i o n s occur west of these boundaries; both are c l e a r l y truncated i n the S t r a i g h t Creek Fault Zone by the S t r a i g h t Creek  20 and Hope F a u l t s .  CASCADE BELT A s i m p l i f i e d view of Cascade s t r u c t u r e i s that of a metamorphic core o v e r l a i n by folded and f a u l t e d sedimentary rocks.  The core was u p l i f t e d  along a north-south a x i s , u p l i f t i n c r e a s i n g northward.  Both core and  f l a n k i n g sedimentary rocks were intruded by T e r t i a r y plutons and o v e r l a i n by T e r t i a r y v o l c a n i c rocks.  A l l of these elements which Misch (1966) des-  cribed i n d e t a i l f o r rocks south of the border, are present i n the study area.  Information i n t h i s s e c t i o n i s from Misch's 1966 r e p o r t , except  where noted; Figure 2-4 i l l u s t r a t e s the geology r e f e r r e d to south of the border. In a recent summary of Northern Cascades geology, Misch (1977) o u t l i n e s three b e l t s divided by the Straight Creek and Ross Lake (Hozameen) F a u l t s ; these b e l t s represent fault-bounded c r y s t a l l i n e core flanked by e a s t e r l y and westerly sedimentary b e l t s .  These d i v i s i o n s are retained i n t h i s study,  but further s u b d i v i s i o n s are a l s o made. Misch's eastern sedimentary b e l t ("East of the Hozameen F a u l t " ) has already been discussed as the Ladner Trough and Hozameen Basin which are c l e a r l y separated by the Hozameen F a u l t i n the study area.  South of the  area (Figure 2-4) the continuation of the Hozameen F a u l t i s the Jack Mountain Prong, a shallow, e a s t e r l y - d i r e c t e d thrust whose upper p l a t e contains the Hozameen Group.  The western contact of the Hozameen Group south of the area  i s defined by the Jack Mountain Prong, but i n the study area i t i s gradat i o n a l i n t o the Custer Gneiss; T e r t i a r y i n t r u s i o n s and volcanism have o b l i t e r a t e d the connection between these features across the border. The c e n t r a l "East of the S t r a i g h t Creek F a u l t " b e l t of Misch (referred to i n t h i s study as C-l) i s composed of "core" rocks of the Skagit  21 Metamorphic S u i t e , whose eastern boundary south of the border i s the Hozameen F a u l t .  In the study area, the equivalent of Skagit rocks, the  Custer Gneiss, grades i n t o the Hozameen Group (McTaggart and Thompson, 1967) along a "zone of shearing, metamorphism and i n t r u s i o n , " which Monger (1970) uses as a boundary f o r s t r u c t u r a l b e l t s .  Monger's boundary has been r e -  tained i n order to separate metamorphic core rocks from o v e r l y i n g Hozameen v o l c a n i c and sedimentary rocks. The western boundary of t h i s b e l t i s the S t r a i g h t Creek Fault Zone, composed of the s u b - p a r a l l e l , graben-forming  Hope and S t r a i g h t Creek ( i . e . ,  Yale) Faults which merge w i t h the Fraser River F a u l t Zone north of Boston Bar.  Misch reports steep (60°)  e a s t e r l y dips and drag f o l d s along the  Straight Creek F a u l t , i n d i c a t i n g d i p - s l i p movement, west s i d e down.  Right-  l a t e r a l movement i s a l s o suggested by drag f o l d s and changes i n s t r u c t u r a l and metamorphic f a c i e s across the f a u l t .  Recent c o r r e l a t i o n of the  Hozameen Group w i t h the Fergusson Group, west of the Fraser River Fault Zone and 190 kilometers north of the f a u l t - t r u n c a t e d Hozameen Group, suggests considerable r i g h t - l a t e r a l movement (Cameron and Monger, 1971). Misch's western b e l t , "West of the S t r a i g h t Creek F a u l t , " i s subdivided i n t e r n a l l y along the Shuksan and Church Mountain Thrust F a u l t s . As the Church Mountain Thrust i s considered a shallow s u b s i d i a r y of the Shuksan, only the l a t t e r i s considered a fundamental boundary i n t h i s study. Between the S t r a i g h t Creek and Shuksan F a u l t s ( s u b d i v i s i o n C-2)  are  rocks of the Shuksan Metamorphic S u i t e , represented by the Darrington P h y l l i t e (D).  This s u i t e was brought up along the w e s t e r l y - d i r e c t e d Shuksan  Thrust, believed to be deep-seated because of associated sheared u l t r a m a f i c rocks and s l i c e s of Yellow Aster basement (YA). West of the Shuksan Thrust, s u b d i v i s i o n C-3 contains sedimentary u n i t s which are complexly folded and f a u l t e d ( i . e . , Church Mountain T h r u s t ) , but  22 are notably less-metamorphosed than Shuksan rocks.  Units i n t h i s b e l t are  the C h i l l i w a c k Group (CH), Cultus.Formation (C), and Nooksack Group (NK). Misch described the Vedder Mountain metamorphic rocks ( s u b d i v i s i o n C-4) as a l a r g e s l i c e of pre-Devonian (Yellow Aster) basement.  Misch  included Vedder Mountain w i t h other basement s l i c e s associated with the Shuksan Thrust, but because of i t s s i z e , post-Devonian age, and d i s t a l p o s i t i o n from the f a u l t , i t i s placed as a separate t e c t o n i c u n i t i n t h i s study.  I t s eastern contact with C-3 sedimentary u n i t s i s a steeply-dipping  f a u l t ; Monger (1970) believed a s i m i l a r f a u l t l i e s to the west, buried i n alluvium. Descriptions of u n i t s w i t h i n the Cascades, t h e i r deformational h i s t o r y and temporal r e l a t i o n s h i p s follow. C-l:  C r y s t a l l i n e Core Rocks This s u b d i v i s i o n represents the northern extension of the Cascade  "core," described by McTaggart and Thompson (1967) as the Custer Gneiss. Banded, migmatitic, augen gneiss i s c l o s e l y associated with coarse pegmat i t i c bodies; amphibolite, metasedimentary and meta-ultramafic s c h i s t , marble, skarn and q u a r t z i t e are present i n l e s s e r amounts.  In places the  Yale i n t r u s i o n s are i d e n t i c a l i n appearance to portions of the Custer Gneiss.  Almandine amphibolite f a c i e s metamorphism dominates Custer rocks,  and g r a n u l i t e f a c i e s i s present l o c a l l y . McTaggart and Thompson b e l i e v e the Custer Gneiss was formed by i s o chemical metamorphism and migmatization of the Hozameen Group; the contact between u n i t s represents a migmatitic front which cuts across l a y e r i n g of Custer and Hozameen u n i t s at a low angle.  Highly sheared and r e c r y s t a l l i z e d  rocks i n the t r a n s i t i o n zone i n d i c a t e that movement also occurred along the zone separating the two u n i t s .  23 Timing of gneiss formation i s not known accurately. Misch  suggested  that Skagit Metamorphism may be synchronous w i t h formation of the Shuksan Suite (see below) which recent work by R. L. Armstrong (personal communicat i o n , 1977) has shown to span the Late J u r a s s i c to Lower Cretaceous  interval.  This age i s considerably younger than Misch's published estimate, determined on s t r a t i g r a p h i c and s t r u c t u r a l grounds.  Skagit Metamorphism i s assumed  to extend from uppermost J u r a s s i c through major mid-Cretaceous orogeny (R. L. Armstrong, personal communication, 1977). The Custer Gneiss i s o v e r l a i n unconformably by Eocene Chuckanut (CK) conglomerate and sandstone which represent c o n t i n e n t a l trough deposits between the Hope and Yale F a u l t s .  In the study area Chuckanut rocks con-  s i s t e n t l y occur along the east s i d e of the Hope F a u l t .  I t i s debatable  whether or not the Chuckanut Formation has been f o l d e d , f o r the geometry of the u n i t i n the study area may be a r e s u l t of d e p o s i t i o n along an a c t i v e f a u l t zone.  Just south of the border, Staatz, et_ a l . , (1972) report that  the Chuckanut Formation has been gently f o l d e d , but only t i l t i n g was  noted  near the border. Oligocene Skagit (SK) v o l c a n i c rocks were deposited unconformably on Custer Gneiss; they cover the Custer/Hozameen contact and l a t e Eocene p l u t o n i c rocks south of the border, but are intruded by l a t e Oligocene i n t r u s i v e phases of the C h i l l i w a c k B a t h o l i t h .  The u n i t , which resembles the  Coquihalla Group, c o n s i s t s of 5,000 feet of gently folded v o l c a n i c flows and p y r o c l a s t i c rocks of a n d e s i t i c to r h y o l i t i c composition. The C h i l l i w a c k composite b a t h o l i t h , composed of t o n a l i t e , g r a n o d i o r i t e and quartz monzonite, i s a h i g h - l e v e l i n t r u s i o n i n which three main phases are recognized:  C h i l l i w a c k b a t h o l i t h , Mt. Barr b a t h o l i t h , and S i l v e r Creek  Stock (Richards and McTaggart, 1976).  H o r n f e l s i c contact aureoles are  c h a r a c t e r i s t i c of these i n t r u s i o n s which cut across a l l e a r l i e r Cascade  24 structures.  These young plutons (40-16 Ma i n the study area) generally are  associated with v o l c a n i c rocks of s i m i l a r ages ( i . e . , Skagit  volcanic  rocks); t h i s a s s o c i a t i o n t y p i f i e s the Cascade B e l t which extends southerly i n t o northern C a l i f o r n i a . Development of the western boundary of the Custer Gneiss occurred during movement of the Straight Creek F a u l t .  Misch bracketed movement  between f a u l t e d Paleocene Chuckanut s t r a t a and upper Eocene i n t r u s i o n s which cut the f a u l t south of the border.  However, Eocene Chuckanut s t r a t a  i n the study area are cut by the f a u l t , c o n t r a d i c t i n g Misch's estimate of an upper l i m i t to f a u l t movement.  I f Chuckanut s t r a t a were assumed to have  been deposited during f a u l t movement, p o s s i b l y as a consequence of movement, then an Eocene and Paleocene age could be envisioned, with no lower l i m i t other than mid-Cretaceous. C-2:  Shuksan Thrust P l a t e The Shuksan Suite represents h i g h l y schistose rocks of the westerly-  directed Shuksan thrust p l a t e , confined between the Shuksan and Straight Creek f a u l t s .  South of the border, t h i s s u i t e consists of a t h i c k meta-  basalt sequence (Shuksan Greenschist) overlying g r a p h i t i c p h y l l i t e s and schistose metagreywackes (Darrington P h y l l i t e ) .  The upper u n i t has not been  reported north of the border, but Misch's 1977 map of the Northwest Cascades implies the continuation of a Darrington/Yellow Aster assemblage north to an area which was previously described Roddick and O k u l i t c h , 1973).  as Chilliwack/Yellow Aster (Monger, 1970;  5  The Darrington u n i t (D) i s a terrigenous  sequence of p h y l l i t e s and  schistose metagreywackes which Misch believes to be derived from a c l a s t i c ^Monger's textures suggests map have  d e s c r i p t i o n of cherty p e l i t e s , limestone pods, r e l i c t v o l c a n i c i n amphibolites and possible a l t e r e d Permian f u s i l i n i d s strongly a C h i l l i w a c k assemblage, but the i m p l i c a t i o n s of Misch's 1977 been adopted here as they were by Richards and McTaggart (1976).  25 sequence which has no non-metamorphic equivalents i n the Cascades.  South of  the border, the o v e r l y i n g Shuksan Greenschist i s characterized by high pressure lower b l u e s c h i s t f a c i e s metamorphism; Brown (1977) estimates operative pressures of seven k i l o b a r s .  The nature of metamorphism of the  Darrington P h y l l i t e i n the study area i s not known, but assumed to be s i m i l a r to that of the Shuksan Greenschist as described above. Deep-seated t h r u s t i n g along the Shuksan Thrust brought up not only the Darrington, but also s l i c e s of basement m a t e r i a l (Yellow Aster Complex) and u l t r a m a f i c rocks.  Along the east s i d e of the Shuksan Thrust, Roddick  and  Okulitch (1973) show a large s l i c e of Yellow Aster (YA) which Monger (1970) described as coarse, l o c a l l y w e l l - f o l i a t e d amphibolites and d i o r i t e s , and massive, f i n e - g r a i n e d amphibolites.  S e r p e n t i n i t e lenses were also reported  to p a r a l l e l f o l i a t i o n s i n a m p h i b o l i t i c rocks composed of f i f t y percent hornblende w i t h epidote, sphene and p l a g i o c l a s e .  Formation of basement  m a t e r i a l probably occurred i n S i l u r i a n and Ordovician, based on pebbles of Yellow Aster i n Devonian conglomerate and i s o t o p i c age determinations of zircons i n Yellow Aster rocks immediately south of the border (Mattinson, 1972).  Emplacement of basement m a t e r i a l i n t h i s s e c t i o n occurred during  Shuksan t h r u s t i n g . Isotopic dates place metamorphism of the Shuksan Suite i n uppermost J u r a s s i c and Lower Cretaceous; d e p o s i t i o n i s believed to have occurred s h o r t l y before, i n Middle and Upper J u r a s s i c (R. L. Armstrong, personal communication, 1977).  These estimates comply w i t h the r e s t r i c t i o n by Misch  that "Shuksan Metamorphism pre-dates the mid-Cretaceous emplacement of the thrust p l a t e and bears no genetic r e l a t i o n to that t e c t o n i c event." Movement along the Shuksan Thrust occurred i n mid-Cretaceous time. Time c o n s t r a i n t s are post-Valanginian and pre-Santonian, i n reference to f a u l t e d Nooksack Group rocks and Nanaimo Group sedimentary rocks which  26 o v e r l i e the f a u l t .  Intense deformation accompanied t h r u s t i n g near the  f a u l t , and i m b r i c a t i o n i s c h a r a c t e r i s t i c . C-3:  Western Flanking Units Sedimentary rocks dominate t h i s s e c t i o n beneath the Shuksan p l a t e .  C h i l l i w a c k (CH), Cultus (C) and Nooksack (NK) rocks represent a long period of d e p o s i t i o n which began i n Pennsylvanian and continued u n t i l major midCretaceous orogeny, except f o r one i n t e r v a l of p o s s i b l e nondeposition around the Permo-Triassic boundary. The C h i l l i w a c k Group i s a sequence of c l a s t i c rocks, limestones and v o l c a n i c rocks.  P e l i t e , s i l t s t o n e and f i n e - g r a i n e d sandstone form the  "base" of the u n i t along the Church Mountain Thrust (true base i s not exposed).  The "base" contains l o c a l arenaceous shallow-water  pods with Lower Pennsylvanian c r i n o i d s .  limestone  Coarse sandstone and conglomerate  record a period of u p l i f t ( a f t e r d e p o s i t i o n of Pennsylvanian u n i t s ) f o l lowed by p e l i t e s , t u f f s and up to 2,000-foot sections of Lower Permian limestone.  The top of the sequence contains arc-type eugeosynclinal v o l -  canic rocks ranging from p i l l o w e d b a s a l t to d a c i t i c p y r o c l a s t i c rocks (Misch, 1977).  Ribboned chert i s interbedded with v o l c a n i c rocks, generally  s t r a t i g r a p h i c a l l y equivalent to or conformably o v e r l y i n g Pennsylvanian limestone.  Monger (1970) states that t h i s s t r a t i g r a p h i c sequence i s  a p p l i c a b l e only to the area south of the Fraser River.  Lowes (1972), who  studied the area north of the Fraser River (see Figure 2-5, below), chara c t e r i z e d the sequence as a v a r i e d sedimentary succession o v e r l a i n by v o l c a n i c rocks, but he d i d not emphasize the presence of limestone. Monger s t a t e s that the C h i l l i w a c k Group c l o s e l y resembles the Hozameen Group l i t h o l o g i c a l l y , but the presence of a l a r g e r amount of The time-space p l o t shows the base of the C h i l l i w a c k Group extending i n t o Devonian, as considerable Devonian limestone occurs south of the border (Danner, 1976).  c l a s t i c m a t e r i a l and evidence of near-shore d e p o s i t i o n and s u b a e r i a l erosion point to an environment of deposition that i s not known elsewhere i n southwestern B r i t i s h Columbia.  The disconformable  contact between C h i l l i w a c k  and Cultus u n i t s i s the r e s u l t of e i t h e r gentle upwarping ( r e f l e c t i n g a deep-seated phenomena), or r a p i d accumulation of the uppermost v o l c a n i c rocks so that a shallow basin could not be  maintained.  The base of the Cultus Formation i s a t h i n , sporadic b r e c c i a l a y e r containing c l a s t s of underlying C h i l l i w a c k v o l c a n i c rocks.  Above t h i s  b r e c c i a i s a sequence of f i n e , t u r b i d i t i c sediments which span the Late T r i a s s i c to mid-Late J u r a s s i c i n t e r v a l .  The Cultus Formation i s a rather  uniform s e c t i o n of a l t e r n a t i n g graded beds of p e l i t e , s i l t s t o n e and f i n e sandstone w i t h rare coarser v a r i e t i e s , cherty p e l i t e s and limestone pods. The Upper J u r a s s i c to lowermost Cretaceous Nooksack Group has been described only by Misch south of the border, although Monger's uppermost Cultus Formation i s temporally equivalent and l i t h o l o g i c a l l y s i m i l a r .  The  most recent maps by Roddick and O k u l i t c h (1973) and Misch (1977) show an area of Nooksack Group west of the westernmost Cultus exposures, but the contact i s covered by alluvium.  Deposited i n a trench environment, the  Nooksack Group c o n s i s t s of rapidly-accumulated, v o l c a n i c a l l y - d e r i v e d greywackes, s i l t s t o n e s and s l a t e s w i t h l o c a l conglomerate, t u r b i d i t e , c l a y and v o l c a n i c i n t e r c a l a t i o n s , c h a r a c t e r i z i n g a deep marine basin w i t h l o c a l highs. The outstanding s t r u c t u r a l features of t h i s s e c t i o n are thrust f a u l t s and f o l d s associated w i t h Shuksan t h r u s t i n g . The Church Mountain Thrust i s considered a shallow off-shoot of the Shuksan "root zone," u p l i f t i n g C h i l l i w a c k and Cultus rocks.  Near the base of the Shuksan, s l i c e s of base-  ment and serpentinized p e r i d o t i t e are imbricated w i t h C h i l l i w a c k rocks of a l b i t e - e p i d o t e amphibolite f a c i e s metamorphism.  The Cultus and Nooksack  u n i t s occur below the Church Mountain Thrust; they are generally believed  28 to be autochthonous,  simply because there i s no evidence that they have  been transported s i g n i f i c a n t l y . Tight, northwesterly overturned f o l d s r e f l e c t i n g t h r u s t geometry were formed during t h r u s t i n g ; penetrative s l a t y cleavage and p h y l l i t i z a t i o n a l s o formed, e s p e c i a l l y i n f i n e r - g r a i n e d rocks.  The same time c o n s t r a i n t s have  been placed on Church Mountain thrust movement as f o r the Shuksan; the possible time span f o r movement centered around mid-Cretaceous time. South of the Fraser River a second episode of f o l d i n g was accompanied by reverse f a u l t i n g , both a f f e c t i n g the o l d e r , major thrust planes.  This  episode i s dated t e n t a t i v e l y as Eocene, when the Chuckanut Formation was a l s o folded s l i g h t l y . Metamorphism of C h i l l i w a c k and Cultus rocks i n t h i s area occurred under moderate t o t a l pressures and high thermal gradients c h a r a c t e r i z i n g metamorphic conditions between prehnite-pumpellyite and b l u e s c h i s t f a c i e s (Beaty, 1972). North of the Fraser R i v e r , Lowes (1972) c h a r a c t e r i z e s metamorphism of the C h i l l i w a c k Group as being d i s t i n c t l y higher grade than i n c o r r e l a t i v e rocks t o the south.  An increase i n metamorphic f a c i e s occurs from west to  east from greenschist to upper epidote amphibolite f a c i e s as the Shuksan Thrust i s approached.  These higher grade rocks are garnetiferous and  hornblende-rich s c h i s t s .  Monger noted that f a u l t s c o r r e l a t i v e w i t h the  Shuksan and Church Mountain Thrusts i n t h i s northern area dip steeply to the east i n contrast w i t h t h e i r r e l a t i v e l y f l a t - l y i n g counterparts to the south. C-4:  Vedder Mountain Wedge Basement rocks on Vedder Mountain, southwest of Hope, belong t o the  Yellow Aster Complex of "ancient" c o n t i n e n t a l crust (Misch, 1966).  Misch  29 describes the area as an autochthonous metamorphic-plutonic complex."  f a u l t wedge of a "highly c r y s t a l l i n e ,  Upper amphibolite f a c i e s metamorphism of  Yellow Aster rocks i s accompanied by younger t e c t o n i c s l i c e s of a l b i t e epidote amphibolite f a c i e s rocks which were dated at 250 Ma  (lowermost  Upper Permian), and b e l i e v e d by Misch to represent a younger metamorphic episode than that which affected the surrounding Yellow Aster Complex. More recent Rb/Sr dates by R. L. Armstrong  (personal communication,  1977)  show that Vedder Mountain "basement" was formed i n Upper Permian to Lowermost T r i a s s i c time; parent rocks are probably Pennsylvanian to Lower Permian. The western edge of Vedder Mountain i s buried i n a l l u v i u m , but i s probably a f a u l t , as the nearest outcrops to the west are of s l i g h t l y metamorphosed J u r a s s i c v o l c a n i c rocks and i n t r u s i o n s of the Coast P l u t o n i c Complex.  SPUZZUM PLUTONIC BELT The Spuzzum P l u t o n i c B e l t i s named a f t e r the i n t r u s i o n s which dominate i t , but minor amounts of T e r t i a r y v o l c a n i c rocks and metamorphic rocks of pre-Spuzzum age are also present.  The b e l t i s delineated by the Fraser  River F a u l t Zone and the Hope F a u l t on the east, the southernmost extension of the Spuzzum i n t r u s i o n s , the n o r t h e r l y extension of the Shuksan Thrust, and a hazy boundary to the west between Spuzzum and Scuzzy i n t r u s i o n s enclosing P a l e o z o i c (?) pendant rocks, and the Coast P l u t o n i c Complex with i t s much more v a r i e d assortment of pendants. Coast P l u t o n i c s t r u c t u r e s merge.  In t h i s b e l t Cascade and  A l l pre-Spuzzum u n i t s have been designated  as e i t h e r Custer Gneiss or S e t t l e r S c h i s t ; p o s i t i v e c o r r e l a t i o n i s not yet p o s s i b l e , but evidence w i l l be c i t e d below which lends support to t h i s suggestion.  Units i n t h i s study are l a b e l l e d according to Roddick and  Okulitch (1973).  30 Metamorphic Rocks Less than 30 percent of the Spuzzum P l u t o n i c B e l t i s composed of h i g h l y metamorphosed (amphibolite grade) pendant rocks which have been studied i n d e t a i l by various persons.  Figure 2-5 shows the study areas of c e r t a i n  workers mentioned i n the f o l l o w i n g d i s c u s s i o n . Referred to as C h i l l i w a c k Group on GSC Map  737A and as Hozameen Group  by McTaggart and Thompson (1967) and Roddick and Hutchison (1969), Lowes (1972) suggests that t h i s uniform sequence of aluminum-rich p e l i t i c s c h i s t s and metamorphosed s i l t s t o n e s and sandstones should be d i s t i n g u i s h e d from the varied sequences of C h i l l i w a c k and Hozameen Groups.  L o c a l i z e d meta-  morphosed breccias and quartz pebble conglomerates, amphibole-bearing s c h i s t s , amphibolite  and quartz feldspar porphyry dikes also characterize  the S e t t l e r Schist (SS).  Pigage (1976) suggests that o r i g i n a l rock types  of the S e t t l e r Schist characterize a eugeosynclinal and less common interbedded carbonate-rich  environment of shales  l a y e r s , conglomerates, t u f f s and  sandstones or cherts. The type area of the S e t t l e r Schist i s east of Old S e t t l e r Mountain, southwest of Yale.  As set out by Lowes, the S e t t l e r Schist i s confined  by  the Hope Fault on the east and the northward extension of the Shuksan Thrust on the west (discussed below), continuing northward to the area described by H o l l i s t e r (1969a,b) northwest of Boston Bar.^ Lowes concluded that Barrovian amphibolite  f a c i e s metamorphism of  unknown age was upgraded by another contact-metamorphic event r e s u l t i n g from i n t r u s i o n of the Spuzzum Pluton.  Pigage concluded that two metamorphic-  ^ H o l l i s t e r describes t h i s area as dominated by greywacke, and reports some pillowed amphibolite. The long, narrow b e l t of northwest-trending serpe n t i n i t e i s c o r r e l a t e d with the Hozameen Fault by Roddick and Hutchison (1969). This move also suggests that the pendant i s a Hozameen and Ladner combination, but t h i s idea has been abandoned f o r a more n o r t h e r l y Hozameen c o r r e l a t i o n , and Lowes believes the pendant to c o r r e l a t e with the S e t t l e r S c h i s t .  31  Figure  2-5.  Study areas of some p r i n c i p l e workers d e a l i n g w i t h t h e metamorphic r o c k s o f t h e Spuzzum P l u t o n i c B e l t . Refer to T a b l e 2-1 f o r d e f i n i t i o n of a b b r e v i a t i o n s .  32 deformational events a f f e c t i n g the S e t t l e r Schist were continuing phases of the same Late Cretaceous orogeny during which the Spuzzum Pluton was emplaced.  H o l l i s t e r considered metamorphism to be the r e s u l t of one  deep-seated prograde contact-metamorphic event occurring during i n t r u s i o n of surrounding plutons.  These c o n f l i c t i n g opinions are a consequence of g  s t r u c t u r a l and metamorphic r e l a t i o n s which have yet to be resolved.  This  study follows Lowes' assumption that an older event which pre-dates Spuzzum i n t r u s i o n must have occurred p r i o r to u p l i f t along the Shuksan Fault east of Harrison Lake (see d i s c u s s i o n below). Regardless of when metamorphism occurred, i t i s generally considered to be deep-seated.  H o l l i s t e r (1969a) estimated e f f e c t i v e pressures between  5.5 and 7.1 k i l o b a r s ; Pigage (1976) estimated pressures between 5.5 and 8.0 k i l o b a r s (18-26 kilometers) and temperatures between 550-700°C. Information on the area northeast of Harrison Lake has been summarized from work by Reamsbottom (1974), who i d e n t i f i e d two conformable s t r a t i g r a p h i c u n i t s which he c a l l e d the Breakenridge and Cairn Needle Formations.  The  Breakenridge Formation i s composed of gneiss w i t h amphibolite, minor migmatite and skarn; the pre-metamorphic assemblage i s believed to be a mixture of greywacke, v o l c a n i c rocks and minor p e l i t e .  The base of the o v e r l y i n g  Cairn Needle Formation i s a stretched-pebble conglomerate which contains I t seems t h a t t h e major d i f f i c u l t y l i e s i n t h e f a c t t h a t a n d a l u s i t e appears to be a contact-metamorphic e f f e c t of t h e Spuzzum and Scuzzy i n t r u s i o n s ; Read ( 1 9 6 0 ) , H o l l i s t e r (1969a,b), Lowes (1972), and P i g a g e (1976) a l l noted the p r e s e n c e of c h i a s t o l i t e pseudomorphs i n the S e t t l e r S c h i s t n e a r p l u t o n s . However, P i g a g e n o t e d t h a t pseudomorphs i n h i s a r e a c o n t a i n p r o d u c t s of r e g i o n a l k y a n i t e - s i l l i m a n i t e metamorphism, s u g g e s t i n g t h a t t h i s h i g h e r p r e s s u r e r e g i o n a l event f o l l o w e d i n t r u s i o n of the Spuzzum. S l i g h t t i l t i n g a f t e r i n t r u s i o n i s proposed t o have caused t h i s i n c r e a s e i n p r e s s u r e . H o l l i s t e r s u g g e s t s t h a t a n d a l u s i t e i s formed m e t a s t a b l y under the same c o n d i t i o n s t h a t formed k y a n i t e and s i l l i m a n i t e , and t h e r e f o r e r e q u i r e s o n l y one e p i s o d e of metamorphism w i t h i n c r e a s i n g t e m p e r a t u r e . These s u g g e s t i o n s do n o t agree w i t h c o n c l u s i o n s reached by Lowes t h a t an e a r l y p e r i o d of d e f o r m a t i o n must have o c c u r r e d b e f o r e u p l i f t a l o n g the Shuksan T h r u s t and i n t r u s i o n o f the Spuzzum p l u t o n .  g r a n i t i c c l a s t s and i n d i c a t e s s l i g h t u p l i f t before deposition of the Cairn Needle Formation.  Above the conglomerate are meta-sedimentary s c h i s t s  (some p e l i t i c ) with minor c a l c - s i l i c a t e s c h i s t and limestone.  Pelites,  conglomerate and limestone i n d i c a t e a v a r i e d shallow marine environment. Reamsbottom c o r r e l a t e d the Breakenridge with the Custer Gneiss and noted that the Cairn Needle merges to the south with the type area of Lowes' 9 S e t t l e r Schist which i s also probably part of the Skagit Metamorphic Suite. Granitoid c l a s t s i n Cairn Needle conglomerates suggested to Reamsbottom that deposition may have occurred post-Coast P l u t o n i c Complex, but Paleozoic conglomerates have a l s o been known to contain such m a t e r i a l .  Age of these  u n i t s i s therefore assumed to correspond to that of the Custer  Gneiss.  Reamsbottom delineated four phases of e s s e n t i a l l y homoaxial pre-Late Cretaceous f o l d i n g , which a f f e c t e d both u n i t s to the same degree.  One of  the l a t e r phases produced l a r g e , gneiss-cored, northwesterly-trending dome structures.  Amphibolite f a c i e s Barrovian metamorphism was synchronous with  f o l d i n g before mid-Cretaceous f a u l t i n g . ^ The d i s t i n c t i o n of the southwestern boundary of the Spuzzum B e l t l i e s i n Lowes' continuation of the Shuksan f a u l t i n t o h i s area.  Factors which  led to h i s conclusion include the f o l l o w i n g : 1) The presence of rocks s i m i l a r to the Yellow Aster Basement Complex; 2)  u l t r a m a f i c rocks (some of which he l i k e n s to alpine-type dunites) whose contacts appear to be t e c t o n i c ;  3)  t r u n c a t i o n of metamorphic isograds; and  9 I t i s i n t e r e s t i n g to note that the v a r i e d Cairn Needle assemblage includes limestone and appears to contrast with Lowes' uniform p e l i t i c sequence which has a notable lack of limestone. ^ C h i a s t o l i t e pseudomorphs were also recognized by Reamsbottom as a contact e f f e c t of Scuzzy i n t r u s i o n . Whereas pseudomorphs i n Pigage's area contain s t a u r o l i t e , those i n Reamsbottom's area contain s i l l i m a n i t e , which does not require an increase i n pressure.  4)  juxtaposed d i s s i m i l a r rock u n i t s .  Unfortunately, Reamsbottom was not able to extend the trace of the Shuksan Thrust any f u r t h e r northward, so the f a u l t i s shown as being the eastern boundary of rocks mapped as C h i l l i w a c k , and i s not followed any f u r t h e r northward than are C h i l l i w a c k rocks. An important outcome of Lowes' work i s the i m p l i c a t i o n that t h r u s t i n g along the Shuksan i n t h i s area brought up rocks resembling s c h i s t s of the Skagit Metamorphic Suite instead of the Shuksan Suite which forms the Shuksan p l a t e to the south.  The conclusion that t h i s b e l t represents the  northward c o n t i n u a t i o n of the Cascade core a x i s at a much deeper s t r u c t u r a l level i s attractive. I n t r u s i v e Rocks The Giant Mascot body i s a l a r g e , crudely-zoned u l t r a m a f i t e located c e n t r a l l y w i t h i n the Spuzzum pluton; i s o t o p i c ages place i t i n the Lower to mid-Cretaceous i n t e r v a l .  I t has been suggested that the Giant Mascot  body i s an early phase of Spuzzum a c t i v i t y (McLeod, 1975), but the r e l a t i o n ship between u l t r a m a f i c rocks and Spuzzum d i o r i t e and t o n a l i t e i s not known w i t h c e r t a i n t y , other than the f a c t that the l a t t e r intrudes the former (Vining, 1977).  I t i s i n t e r e s t i n g to note that the Giant Mascot body a l s o  l i e s at the southeastern end of a northwesterly-trending b e l t of u l t r a m a f i c rocks which are believed to have been emplaced t e c t o n i c a l l y along the midCretaceous Shuksan Thrust.  Unfortunately, the connection between Giant  Mascot and the Shuksan b e l t i s masked by the Spuzzum pluton. The Spuzzum and Scuzzy plutons are considered to be the  easternmost  extension of the Coast P l u t o n i c Complex, and y i e l d Cretaceous K/Ar  dates  (see Figure 2-2) that correspond to the major pulse of Coast P l u t o n i c intrusion.  Richards and McTaggart (1976) show the Spuzzum as a zoned  35 i n t r u s i o n of three d i o r i t i c phases surrounded by a l a t e r margin of t o n a l i t e (quartz d i o r i t e ) .  The Scuzzy pluton was considered younger than the  Spuzzum pluton (Roddick and Hutchison, 1969) because of a supposed genetic r e l a t i o n s h i p between Scuzzy and H e l l ' s Gate plutons (see below), but K/Ar dates have not been able to d i s t i n g u i s h Scuzzy and Spuzzum plutons as separate i n t r u s i v e events.  The Scuzzy i s l i t h o l o g i c a l l y d i s t i n c t from the  Spuzzum, composed of coarse g r a n o d i o r i t e w i t h l e s s than f i v e percent mafic content, contrasting w i t h the 15-25 percent mafic content of the Spuzzum. H e l l ' s Gate pluton i s an Eocene to Oligocene fine-grained i n t r u s i o n of granodiorite that i s truncated by the Straight Creek F a u l t . T e r t i a r y Volcanic Rocks The only reference to Miocene-Pliocene a c i d v o l c a n i c rocks (av) appears i n Roddick and Hutchison (1973), who admit that the age of these rocks i s " l i t t l e more than a deflected guess."  Unconformable on p l u t o n i c rocks and  generally f l a t - l y i n g with l o c a l dips of 30° or l e s s , these v o l c a n i c rocks are remnants of a "once extensive cover of . . . r h y o l i t i c to d a c i t i c p y r o c l a s t i c s and flows."  COAST PLUTONIC BELT F i f t y - f i v e percent of the study area consists of rocks of the Coast P l u t o n i c B e l t , a t e c t o n i c province w i t h about 20 percent non-plutonic rocks which occur as pendants or remnant u n i t s .  Most pendant rocks are e i t h e r  h i g h l y deformed and metamorphosed or r e g i o n a l l y a l t e r e d during i n t r u s i o n of p l u t o n i c rocks, although l o c a l unaltered areas are known.  Cover u n i t s are  dominantly v o l c a n i c and volcano-sedimentary, although a sedimentary record of erosion of the Coast Range i s preserved i n the southernmost p o r t i o n of the b e l t .  36 Pendant Rocks Older Units of Unknown Age The oldest named u n i t s which occur as pendants i n the Coast P l u t o n i c Belt are the Twin Islands (TI) and Bowen Island (BI) Groups.  Except where  noted, information concerning these u n i t s was obtained from Roddick (1965). The Twin Islands Group forms small pendants which commonly appear to grade i n t o surrounding i n t r u s i v e rocks through migmatitic zones.  Rock  types include g r a n u l i t e , amphibolite, micaceous q u a r t z i t e , p h y l l i t e , s c h i s t and gneiss, w i t h minor q u a n t i t i e s of conglomerate, meta-andesite, rhyod a c i t e and h o r n f e l s .  Metamorphism i s generally high-grade ( i . e . , upper  amphibolite), but examples of pendants containing s m a l l , s c a r c e l y - a l t e r e d areas are reported.  This group i s a c a t c h - a l l f o r rocks which have under-  gone a period of intense metamorphism and therefore may varying ages.  include rocks of  Age of the group i s estimated as Pennsylvanian-Permian  according to Roddick and O k u l i t c h (1973).  Highly metamorphosed cong-  lomerates contain cobbles of p l u t o n i c rocks which must have been derived from an older p l u t o n i c terrane.  At the northern end of Harrison Lake, rocks  mapped by Roddick as Twin Islands Group correspond  to a s e c t i o n of  Reamsbottom's Cairn Needle Formation (Custer Gneiss), also of unknown age. A l a r g e pendant northeast of Squamish i s mapped as having Twin Islands Group i n the south and younger, less-deformed  Gambier Group (G) i n the  north (see below). The Bowen Island Group occurs on and near Bowen Island.  I t i s dom-  inated by massive, a n d e s i t i c greenstone flows w i t h minor interbedded sedimentary rocks, which are thinly-banded, cherty and tuffaceous. morphism i s up to greenschist f a c i e s . thought to be present.  Meta-  Several thousand feet of s t r a t a are  The age of t h i s group i s unknown, but i s placed at  37  Lower to mid-Upper T r i a s s i c because Roddick b e l i e v e d i t to be older than the Cultus Formation and younger than the Twin Islands Group.''''' Roddick and Okulitch (1973) placed the Bowen Island Group i n the T r i a s s i c . Three unnamed u n i t s of unknown age are shown as "m,"  "ms,"  and "gn"  on Figure 2-1, but do not appear on the time space p l o t (Figure 2-2).  Many  p o s s i b l y are more h i g h l y metamorphosed equivalents of surrounding u n i t s . Only b r i e f d e s c r i p t i o n s are a v a i l a b l e f o r each as f o l l o w s : m:  Undivided metamorphic rocks i n c l u d i n g gneiss, s c h i s t , h o r n f e l s , metavolcanic rocks, q u a r t z i t e , greywacke, s l a t e , a r g i l l i t e , migmatite, and agmatite (Bostock, 1963).  ms:  Metasedimentary rocks i n c l u d i n g micaceous q u a r t z i t e , biotite-hornblende s c h i s t , s c h i s t s bearing garnet, s t a u r o l i t e and p o s s i b l y s i l l i m a n i t e (Roddick and Hutchison, 1973).  gn:  G n e i s s i c units i n c l u d i n g g r a n i t o i d gneiss, migmatitic complexes, and minor amphibolite and b i o t i t e s c h i s t (Roddick and Hutchison, 1973). Roddick and O k u l i t c h (1973) c o r r e l a t e d some of these pendants w i t h the Twin Islands Group or Custer Gneiss.  Harrison Lake Sequence A short i n t e r v a l of volcanism on the west s i d e of Harrison Lake i n Bajocian (lowermost Middle J u r a s s i c ) time was followed by sporadic s e d i mentation through Hauterivian (mid-Lower Cretaceous) time.  F o s s i l s have  been of great importance i n determining ages of these u n i t s , a r a r i t y f o r Coast P l u t o n i c Belt pendant rocks whose f o s s i l ages are generally indeterminate.  Information concerning these formations i s taken from Monger (1970),  except where noted. Approximately 9,000 feet of intermediate to acid p y r o c l a s t i c and flow rocks make up the Harrison Lake Formation (HL).  Rock types include kerato-  ^The l a t t e r r e s t r i c t i o n i s based on the l e s s e r degree of metamorphism, but he also suggests that i t may be a less-metamorphosed equivalent of the Twin Islands Group.  38 phyre, quartz-keratophyre, meta-andesite and d a c i t e .  P y r o c l a s t i c rocks  include v o l c a n i c breccias with fragments up to one foot i n diameter and l i t h i c and c r y s t a l t u f f s ; flows are commonly p o r p h y r i t i c , massive, or l o c a l l y columnar j o i n t e d . also Bathonian.  F o s s i l s i n d i c a t e a Bajocian age, and p o s s i b l y  This formation conformably o v e r l i e s sandstone, black  a r g i l l i t e and t u f f l a b e l l e d as Cultus Formation, but whose i d e n t i t y and age are, i n f a c t , unknown.  Contemporaneous volcanism s i m i l a r to that of the  Harrison Lake Formation occurred south of the border i n the Cascades (Misch, 1966). Conformably o v e r l y i n g the Harrison Lake Formation i s a s e r i e s which includes the Echo I s l a n d , Mysterious Creek and B i l l h o o k Creek Formations, grouped together on the compilation map BME.  (Figure 2-1) f o r convenience as  Waning volcanism i s represented by nearly 3,000 feet of w e l l -  s t r a t i f i e d , fine-grained t u f f and minor agglomerate, sandstone, and a r g i l l i t e of the Echo Island Formation.  Two to three thousand feet of uniform black  calcareous a r g i l l i t e of the Mysterious Creek Formation o v e r l i e Echo I s l a n d , and contain mid-Callovian f o s s i l s .  These a r g i l l i t e s grade upward i n t o the  B i l l h o o k Creek Formation, composed of f i n e t u f f s and v o l c a n i c sandstones with an apparant thickness of 1,800 feet.  This gradational r e l a t i o n s h i p  implies the B i l l h o o k was deposited during upper C a l l o v i a n ; B r o o k f i e l d also reports lower Oxfordian f o s s i l s .  (1973)  These three formations are found  west of Long Island i n Harrison Lake as a conformable s e r i e s which was mapped by Roddick on the adjacent western map sheet as the F i r e Lake Group (FL) which i s discussed below. Three thousand feet of poorly-sorted conglomerate (notably without g r a n i t i c pebbles) of the Kent Formation (K) i s sandwiched between two black a r g i l l a c e o u s u n i t s south of Harrison Lake.  A r g i l l i t e occurring conformably  (?) below the conglomerate i s believed to be the mid-Callovian Mysterious  Creek Formation; the s e c t i o n above i s r e f e r r e d to as the Agassiz P r a i r i e Formation (AP).  Interbeds of sandstone, t u f f and limestone are also  present w i t h i n t h i s upper a r g i l l i t e sequence.  I f Oxfordian a r g i l l i t e s on  the  Cascade Peninsula can be considered to be Agassiz P r a i r i e Formation,  the  Kent Formation must also be Oxfordian, but B r o o k f i e l d (1973) considered  the  Cascade Peninsula outcrop to be equivalent to the B i l l h o o k Creek  Formation, i n which case both the Kent and the Agassiz P r a i r i e Formations can only be r e f e r r e d to as post-Oxfordian. Conglomerate with g r a n i t i c pebbles which resemble i n t r u s i v e rocks occurring seven miles west of Harrison Lake, forms the base of the 1,260foot t h i c k Peninsula Formation (PN) which r e s t s w i t h angular unconformity on the B i l l h o o k Creek Formation.  Arkosic sandstone forms the remainder,  and Lowes (1972) reports layers of limestone. Valanginian f o s s i l s have been described.  B e r r i a s i a n and lower  This formation may i n f a c t be the  Nooksack Group, as they are temporally equivalent.  Nooksack conglomerate  on Vedder Mountain was mapped by Monger as p o s s i b l e Peninsula Formation because of s i m i l a r c l a s t m a t e r i a l . Conformable above the Peninsula Formation i s the 3,700-foot t h i c k Brokenback H i l l Formation (BH) of Valanginian, Hauterivian, and p o s s i b l y younger ages (the top i s f a u l t e d against older rocks).  Tuff and agglomerate  w i t h minor amounts of sandstone and shale form a lower s e c t i o n o v e r l a i n by bedded greywackes.  Roddick (1965) mapped the westernmost extensions of the  Peninsula and Brokenback H i l l Formations as F i r e Lake Group(FL). F i r e Lake and Gambier Groups; Pioneer Formation The F i r e Lake Group (FL) i s described i n d e t a i l by Roddick (1965). B e r r i a s i a n f o s s i l s were located i n limestone of the lower member of the group, and i t includes Bathonian, C a l l o v i a n and Oxfordian u n i t s described  40 above.  The questionable extension up i n t o A l b i a n time i s a r e s u l t of  l i t h o l o g i c c o r r e l a t i o n with the Gambier Group. L i t h o l o g i c d i v i s i o n s w i t h i n the F i r e Lake Group are based on u n i t s of the large pendant northwest of Harrison Lake.  A lowermost s e c t i o n of  12 fine-grained g r a n u l i t e  and minor andesite, limestone and conglomerate i s  o v e r l a i n by a s e c t i o n of s l a t e and a r g i l l i t e with minor amounts of greywacke.  Above these u n i t s i s a t h i c k greenstone member with some conglom-  erate, q u a r t z i t e and greywacke.  Conglomerates contain appreciable g r a n i t i c  d e t r i t u s , but some plutons are c r o s s - c u t t i n g . i s estimated at 15,000 f e e t .  The thickness of the group  Metamorphism of a l l u n i t s i s s l i g h t except f o r  the lowermost g r a n u l i t e u n i t which i s amphibolite f a c i e s . The Gambier Group i s characterized by a n d e s i t i c to d a c i t i c v o l c a n i c and sedimentary rocks whose complexity, rapid f a c i e s changes and of f o s s i l s make c o r r e l a t i o n s between pendants d i f f i c u l t .  paucity  However, the  general character of volcanism has led to the designation of rocks i n an increasing number of pendants as Gambier Group.  On Gambier I s l a n d , Gambier  Group rocks unconformably o v e r l i e Upper J u r a s s i c p l u t o n i c rocks (McKillop, 1973); l a t e r plutons intrude pendant rocks. Roddick (1965) describes an approximately 6,000-foot s e c t i o n east of Gambier Island w i t h three subdivisions l y i n g unconformably ( i n places v e r t i c a l l y ) on p l u t o n i c and metamorphic rocks.  A basal conglomerate with  g r a n i t i c cobbles i s o v e r l a i n by a n d e s i t i c flows and p y r o c l a s t i c rocks of the lowermost d i v i s i o n . The middle u n i t consists of s l a t e , a r g i l l i t e , arkose and q u a r t z i t e .  Andesite and t u f f comprise the upper unit whose top  has  been removed by erosion. A l b i a n ammonites were recovered from s l a t y _ Roddick (1965) defines g r a n u l i t e as "a f e l d s p a t h i c metamorphic rock having a r e l a t i v e l y even granular texture, s i m i l a r to an amphibolite, but containing l e s s than 50 percent amphibole. Most of these rocks f a l l i n the amphibolite f a c i e s . . . not the g r a n u l i t e f a c i e s . . . ."  41 a r g i l l i t e i n t h i s area. The large pendant north of t h i s s e c t i o n was described o r i g i n a l l y by James (1929) as the B r i t a n n i a and Goat Mountain Formations.  Here an almost  20,000-foot section whose sequence d i f f e r s s l i g h t l y from that to the south i s similar lithologically. The Cheakamus, Empetrum and Helm Formations (CEH) were described o r i g i n a l l y by Mathews (1958) as Upper Cretaceous sedimentary rocks north of Squamish, but recent reassignment of f o s s i l s found i n the Cheakamus 13 Formation implies a Lower Cretaceous age (Roddick, et a l . , 1977).  Basal  conglomerate of g r a n i t i c and greenstone pebbles s i m i l a r to that of the Gambier Group, along w i t h a Lower Cretaceous age and the f a c t that formations are cut by l a t e r i n t r u s i v e phases has l e d to the i n c l u s i o n of these formations i n the Gambier Group.  The sequence here i s not c l e a r , as  formations are i n f a u l t contact w i t h each other, but there appears to be more than 20,000 feet of section.  Several thousand feet of v o l c a n i c rocks  are present and sedimentary rocks appear to contain an appreciably higher proportion of coarser-grained u n i t s than to the south.  Limestone and limy  sedimentary rocks also appear to be more common here. The Pioneer Formation, of Norian age, o r i g i n a l l y r e f e r r e d to a small, 1,000-foot s e c t i o n of v a r i a b l e greenstones (with minor amounts of r h y o l i t e ) north of the study area near Bralorne, but was extended southward on f o s s i l evidence by Roddick and Hutchison (1973) to a 5,000-foot sequence north of Pemberton.  An unpublished map by Woodsworth (ca. 1975) extended the form-  a t i o n even f u r t h e r south to include two s u b - p a r a l l e l pendants north of Garibaldi. __  Roddick and O k u l i t c h (1973) consider these same pendants as part ———  Green (1977) suggests that the Empetrum i s not part of t h i s s e c t i o n , but pre-Cretaceous, as i t contains h i g h l y metamorphosed rocks, and dolomitic interbeds w i t h i n the greenstone.  42 of the F i r e Lake Group, whereas Roddick, et_ a l . , 1977, and Woodsworth, 1977, consider them Gambier Group.  The most recent c o r r e l a t i o n w i t h the Gambier  Group has been adopted i n t h i s study, although i t i s by no means c e r t a i n . No g r a n i t i c pebble conglomerates  have been reported i n these northern  pendants, and sedimentary rocks are a very minor component; limestone occurs l o c a l l y .  The overwhelming m a j o r i t y of pendant rocks are intermediate  to acid p y r o c l a s t i c and flow rocks.  The western pendant has y i e l d e d one  reasonable K/Ar date of 124 + 4 Ma (see d i s c u s s i o n of Northair Mine, Chapter Two).  14  Greenschist f a c i e s metamorphism a f f e c t e d the majority of Gambier Group rocks.  Deformation i s l o c a l i z e d along northwesterly-trending zones of  intense f o l i a t i o n , many of which are p y r i t i c .  These f o l i a t e d zones are  commonly r e f e r r e d to as "shear zones," although i n many i t i s questionable whether shear displacement has a c t u a l l y occurred.  One such zone of major  proportions i n the B r i t a n n i a pendant w i l l be discussed i n d e t a i l i n Chapter Two. P l u t o n i c Rocks I n t r u s i v e rocks representing the Coast P l u t o n i c Complex (CR) i n the study area are most commonly reported to be quartz d i o r i t e or g r a n o d i o r i t e , but other types of coarse-grained g r a n i t i c rocks (except syenite) are represented i n l e s s e r amounts.  A northwesterly-trending f o l i a t i o n p a r a l l e l i n g  pendant contacts i s common; contacts w i t h pendants are sharp or g r a d a t i o n a l . Included w i t h rocks designated as p l u t o n i c are migmatitic complexes containing over 50 percent p l u t o n i c rock.  B r i t t l e deformation i s generally  exhibited i n these rocks through f a u l t i n g and/or b r e c c i a t i o n  (Roddick,  1965). 14  G r e e n (1977) a l s o considers these pendants pre-Cretaceous, s p e c i f i c a l l y , J u r a s s i c , but does not s t a t e what c r i t e r i a led to t h i s conclusion.  43 The e a r l i e s t record of i n t r u s i v e a c t i v i t y occurs on Gambier Island and near the north end of Howe Sound; K/Ar dates are Upper J u r a s s i c .  A  30 m i l l i o n year gap occurs before the main pulse of plutonism i n upper Lower Cretaceous and Upper Cretaceous.  One upper Paleocene date was  obtained j u s t outside the study area, south of Pemberton. P o s t - P l u t o n i c Rocks Dominantly Eocene u n i t s exposed s p o r a d i c a l l y i n the Fraser River d e l t a area consist of sedimentary and b a s i c v o l c a n i c rocks l a b e l l e d " s " and r e s p e c t i v e l y (Figure 2-1). conglomerate  Sedimentary  "bv,"  rocks include sandstone, shale and  (some t u f f and coal) which l i e unconformably  on p l u t o n i c rocks  and thicken to about 9,000 feet south toward the United States border. Shales become dominant to the south, i n d i c a t i n g a northern source  (i.e.,  Coast Range), but younger u n i t s thicken southward, i n d i c a t i n g a more recent southern source.  These c o n t i n e n t a l f l o o d p l a i n deposits contain mostly  Eocene f o s s i l s , but l a t e Campanian i s recorded north of Burrard I n l e t , and Roddick (1965) believed that younger, more southern u n i t s might be Oligocene. Rare b a s a l t and t u f f interbeds i n the above-described sedimentary rocks are l o c a l l y t h i c k enough to map as a separate u n i t .  Fine-grained, p o r p h y r i t i c  b a s a l t i s l o c a l l y columnar-jointed, but o r i g i n as flows or s i l l s has not been determined.  Dikes and rare p y r o c l a s t i c rocks are a l s o present.  Quaternary, c a l c - a l k a l i n e Cascade volcanism extends from northern C a l i f o r n i a through Oregon and Washington, i n t o B r i t i s h Columbia where i t appears as the P l e i s t o c e n e to Recent G a r i b a l d i Group (GB; Green, 1977). B a s a l t , andesite and d a c i t e flows were extruded on the g l a c i a t e d surface of the Coast Mountains.  There i s evidence of e x t r u s i o n contemporaneous with  g l a c i a t i o n ; pre- and p o s t - g l a c i a l lavas flowed along present v a l l e y f l o o r s which are s t i l l occupied by r i v e r s .  44 SUMMARY AND DISCUSSION A t e c t o n i c summary of the study area i s presented i n Table 2-4, and a generalized discussion of a p l a t e t e c t o n i c model f o l l o w s . The evolution of the Canadian C o r d i l l e r a has been described as the development of a s e r i e s of Upper Paleozoic-Lower Mesozoic v o l c a n i c arcs o f f the coast of the c o n t i n e n t a l craton, successively added to the through subduction (Monger, et_ a l . , 1972).  craton  As each arc c o l l i d e d with  the  craton, the r e l a t e d subduction zone ceased to f u n c t i o n , and another one began to operate west of the arc.  Figure 2-6 i l l u s t r a t e s t h i s process and  shows the l o c a t i o n s of p o s s i b l e subduction zones i n the C o r d i l l e r a . To r e l a t e t h i s model to the study area, one can view the mid-Cretaceous event discussed above as r e s u l t i n g from c o l l i s i o n between the P a c i f i c P l a t e , carrying a v o l c a n i c - p l u t o n i c arc (Coast P l u t o n i c Complex), and the craton, to which the Omineca and Intermontane B e l t s have also been added.  Meta-  morphic core rocks of the Spuzzum and Cascade Belts mark the axis of compression, bounded by oppositely-verging  thrusts (see Figure 2-la) ,  i l l u s t r a t i n g the compressive force which moved m a t e r i a l up and away from the convergent zone. Subduction responsible f o r the Coast P l u t o n i c Complex ceased a f t e r mid-Cretaceous c o l l i s i o n , although i n t e r m i t t e n t plutonism did occur through Miocene.  Subduction responsible f o r Cascade volcanism i s a more recent  phenomenon which overlaps the Coast P l u t o n i c arc i n the study area, but does not continue f a r northward where p l a t e i n t e r a c t i o n i s of a transcurrent nature. As suggested i n Figure 2-6A, transcurrent motion.  subduction was  followed by r i g h t - l a t e r a l  This change i s i l l u s t r a t e d i n the study area by Upper  Cretaceous compression followed by transcurrent movement i n Lower T e r t i a r y along the Straight Creek/Fraser River Fault System.  TABLE 2-4. SUMMARY OF TECTONIC HISTORY  TIME SPAN I. II.  III. IV.  VI.  VII.  VIII.  IX.  X.  XI.  EVENTS  UNITS INVOLVED (see Figures 2 - 1 , 2-2)  Pre-Devonian  Formation of basement  YA i n C-2  Upper P a l e o z o i c / Lower and Middle T r i a s s i c  Marine eugeosynclinal d e p o s i t i o n i n a basin which shallows westward (or, i f r i g h t - l a t e r a l o f f s e t i s considered, shallows t o the south).  CH.HZ (TI?,BI?,YA i n C-4?)  Permian/Triassic  Deformation  YA i n C-4 (TI?,BI?)  Upper T r i a s s i c  Volcanism i n the Coast P l u t o n i c Belt and extensively east of the study area forming the Intermontane B e l t . Deposition of marine t u r b i d i t e s begins i n the southern s e c t i o n .  PI.N C  Lower and Middle J u r a s s i c  Deep-water deposition In the Ladner Trough begins from a high source area to the east. Deposition continues i n the south, and a burst of a c i d i c volcanism occurs on the eastern edge of the Coast P l u t o n i c B e l t , followed by d e p o s i t i o n i n l o c a l basins of varying r e l i e f .  L C,D HL,BME  Upper J u r a s s i c  Plutonism of unknown extent i n the Coast P l u t o n i c B e l t , and some d e p o s i t i o n . Deformation and metamorphism begins along a north-south a x i s i n the Spuzzum and Cascade B e l t s . Deposition of t r e n c h - l i k e sediments along t h i s a x i s begins. Shallow-water deposition of more e a s t e r l y - d e r i v e d sediments i n the Ladner Trough and p o s s i b l e i n t r u s i o n of the Eagle Complex.  CR.FL (AP?,K?) SS, Custer Gneiss D DC Eagle ?  Lower Cretaceous  Considerable marine volcanism and sedimentation i n the Coast P l u t o n i c Belt along with the beginning of intense plutonism and/or c o o l i n g of s a i d plutons to the point where they have begun to r e t a i n argon to produce radiometric dates. A x i a l deformation continues, and the Giant Mascot Ultramafic body has a l s o cooled s u f f i c i e n t l y to produce K/Ar dates. Trenchl i k e deposition along the metamorphic a x i s ceases by mid-Lower Cretaceous. Easterlyderived marine deposition continues i n the Ladner Trough, but becomes westerly-derived and non-marine by the close of A l b i a n time, i n d i c a t i n g considerable u p l i f t to the west, presumably of the Coast P l u t o n i c Complex. The Eagle Complex i s a l s o shedding debris i n t o the Ladner Belt by A l b i a n .  G,CEH,FL,PN,BH CR SS, Custer Gneiss D um NK JM,P  mid-Cretaceous ( l i m i t s undefined)  Major t h r u s t i n g d i r e c t e d away from the c e n t r a l Shuksan, Church Mountain, metamorphic a x i s brought up mantle-derived (?) Hozameen, Pasayten Faults u l t r a m a f i c rocks and basement m a t e r i a l . um G e n e t i c a l l y - r e l a t e d f o l d i n g accompanied Eagle t h r u s t i n g i n the Cascade B e l t , Hozameen Basin and Ladner Trough. The Eagle P l u t o n i c Belt was a l s o u p l i f t e d a t t h i s time. Figure 2-la i l l u s t r a t e s t h i s deformation episode, and includes l a t e r f a u l t i n g as w e l l .  Upper Cretaceous  The majority of the Coast P l u t o n i c Complex (and Spuzzum) K/Ar dates are c l u s t e r e d In t h i s p e r i o d , but by the end of Cretaceous time l a r g e - s c a l e plutonism had ceased. Major deformation and t h r u s t i n g i n a l l areas have a l s o ceased by l a t e s t Cretaceous.  CR, Spuzzum, Scuzzy  Tertiary  The Coast P l u t o n i c Belt records volcanism and sedimentation which began i n l a t e s t Cretaceous, recording,continued u p l i f t and erosion of theJCoast Mountains. One K/Ar date records l a t e c o o l i n g / i n t r u s i o n of p l u t o n i c rocks. Major r i g h t - l a t e r a l movement along the S t r a i g h t Creek/Fraser River Fault Zones and r e l a t e d (?) sedimentation and i n t r u s i o n occurred before Oligocene. High-level plutons are concentrated i n the Cascade B e l t , but are a l s o scattered throughout the area; coeval v o l c a n i c rocks were extruded.  s.bv.CR ' S t r a i g h t Creek/Fraser River F a u l t Zone, CK, Yale Intrusions H e l l ' s Gate, S i l v e r Creek, C h i l l i w a c k , Mt. Barr, Needle Peak av,SK,CQ  C a l c - a l k a l i n e volcanism occurred i n the Coast Plutonic Belt.  GB  Pleistocene  °1  46  t£2>  500 rnls  B  GRANITIC ROCKS; INCLUDED SOLELY FOR REFERENCE BLUESCHISI  LOCALITIES  CANADIAN CORDILLERA  I  V- PAL.-*  \  Figure 2-6. A.  FRAGMENTS OF OLD ISLAND ARCS \ ^. ° r |!| |T IN NORTHWESTERN BRITISH COLUMBIA? OCEANIC CRUST C  v  :  N  T  N  N T A L  '  P o s s i b l e subduction zones i n the Canadian C o r d i l l e r a ; l a t e r transcurrent motion suggests oblique subduction. Method of a c c r e t i o n of c r u s t a l blocks, r e s u l t i n g i n westward "jumping-out" of subduction zones. (Transcurrent or normal p l a t e i n t e r a c t i o n may be respons i b l e f o r c r u s t a l accretion.) (from Monger, et a l . , 1972)  47 3.  METAL DEPOSITS  INTRODUCTION P u b l i c records were examined f o r a t o t a l of 258 metal deposits i n the study area (Figure 1-2), but t h i r t y of these are not described  adequately  i n the a v a i l a b l e l i t e r a t u r e except f o r l o c a t i o n and perhaps general commodity data.  Of the remaining 228 deposits, 86 percent are small  that have never produced.  occurrences  A d i s c u s s i o n of every deposit i s not necessary to  give the reader an appreciation of m i n e r a l i z a t i o n which characterizes the study area.  An a l t e r n a t i v e approach i s to present information only on  deposits of the f o l l o w i n g three categories: 1) major mines and r e l a t e d occurrences 2) mining camps without major mines 3)  i s o l a t e d past-producers  and important  prospects  Table 3-1 i s a compilation of production records from a l l deposits i n the study area f o r which such information i s a v a i l a b l e . Those producing deposits which are not included i n discussions of d i s t r i c t s and camps of the f i r s t and second categories o u t l i n e d above w i l l be presented and d i s cussed b r i e f l y i n the t h i r d s e c t i o n .  Figure 3-1 shows l o c a t i o n s of  d i s t r i c t s , camps and i n d i v i d u a l deposits which w i l l be considered i n t h i s chapter.  Tabulation of the c h a r a c t e r i s t i c s of these deposits i s presented  w i t h each d i s c u s s i o n ; abbreviations and symbols used i n these tables are defined i n Table 3-2. Discussion of deposits i n the categories o u t l i n e d above w i l l  acquaint  the reader w i t h about two-thirds of the deposits i n the area f o r which g e o l o g i c a l information i s a v a i l a b l e . The remaining deposits, generally the smallest and l e a s t known of the p u b l i c a l l y documented occurrences i n the study area, w i l l not be discussed.  Mac No. Name G-3 Britannia  Production  Metals  Produced  52,783,964 T  Cu,Zn,Pb,Ag,Cd,Au  G-5 Zel G-14  Reference  Time of Production  BCDM  1905-1974  MMAR  p r i o r to 1890  70 T  Cu.Zn.Ag  BCDM  1907,1917  1,566 T  Cu.Ag (Au)'  BCDM  1949,1952,1961,1963  95 T  Cu.Ag  BCDM  1940  15,047 T  Cu,Ag,Au  BCDM  1932-39  200 l b s  Au  BCDM  1897  Lorraine G-23 Cambrian C h i e f t o n G-24 King Midas G-25 Ashloo G-26 Money Spinner  MMAR  1,500 T i n dump and thousands of tons i n s i g h t Cu.Ag  198 T  C--34  Viking  1916  BCDM  16,000 T estimated present  MMAR  55 T (includes G-26)  GEM^ 1972, p. 104  250,000 T estimated present  MMAR  HSW- 1 Canam  25 T  MMAR  p r i o r to 1947  HSW-2 Invermay  99 T  Zn.Pb.Ag (Au)  BCDM  1936,1941,1947  HSW-4 Giant Mascot  6,081,133 T  Ni.Cu  GEM, 1974, p. 105-6  1933-1937, 1958-1974  HSW-8 Empress  100 T  Cu  BCDM  1917  HSW-11 Eureka-Victoria  1 high-grade  MMAR  e a r l y 1870's  HSW-13 • Seneca  287 T  Zn,Cu,Ag,Au  BCDM  1962  HSW-15 V a l l e y View  50 T  Cu.Ag  BCDM  1961  HSW-16 S i l v e r Chief  1 T  Ag.Cu  BCDM  1926  G-36  Dandy  '  shipment  MMAR  130 T lead concentrate and 1 carload z i n c concentrate HSW-18 Eureka  23 T  HSW-25 S i l v e r Daisy  28 T  HSW-33 Anna  1 carload  HSW-34 Emancipation  638 T  HSW-36 Aufeus  537 T  HSW-42  8T  1897  1929,1956 MMAR 1926 Pb.Zn.Ag (Au)  BCDM 1916,1929 MMAR 1920  Au,Ag,Pb,Zn  BCDM 1916-1941  Cu,Ag,Au  BCDM  Ag  BCDM  1937-1941  1915  B.B. (Rainbow) GEM, 1972, p.  350 T  HNW-2 Providence HNW-3 Aurum  545 T  HNW-11 Pipestem  1,650 T  HNW-15  Au, Ag  BCDM  Cu,Au,Ag  BCDM  Au  BCDM  Pb,Cu,Ag (Au)  BCDM  104  Ward  J-45  350 T  1879-1899  1930-1942  1935-1937 1905 1970  Astra,Cambria 29 sacks o f " s e l e c t e d " m a t e r i a l shipped  J-51 Van S i l v e r J-130 Northair  67,100 T  Zn,Pb,Cd,Ag,Au  MMAR  1934  N o r t h a i r Mines L t d . Annual Report, 1977  1976-1977  1 Metals a r t l i s t e d i n decreasing order of amounts shipped i f such i n f o r m a t i o n i s a v a i l a b l e . B r i t i s h Columbia  Department of Mines and Bureau of Economics and S t a t i s t i c s , V i c t o r i a , B r i t i s h  Columbia  ^Annual Reports of the B r i t i s h Columbia M i n i s t e r of Mines Parentheses shipped.  i n d i c a t e very minor production; In the cases s p e c i f i e d above l e s s than 20 ounces of the metal was  Geology, E x p l o r a t i o n and Mining i n B r i t i s h  Columbia  Figure 3-1.  P r i n c i p a l areas of mineral occurrences, Vancouver-Hope area.  Table 3-2. ABBREVIATIONS AND SYMBOLS USED IN DEPOSIT DESCRIPTIONS ac  actinolite  ml  malachite  ak  ankerite  Mn  manganese s t a i n  am  amphibole  mo  molybdenite  an  anhydrite  Mo  molybdenum  ap  arsenopyrite  mr  marcasite  ar  argentite  po  pyrrhotite  at  apatite  pr  pyrolusite  Au  native  Pt  pentlandite  az  azurite  pyrite  ba  barite  py qz  Bi  native  sb  stibnite  bo  bornite  SC  specularite  ca  calcite  sd  siderite  cb  carbonate  sh  scheelite  cc  chalcocite  si  sphalerite  cl  chlorite  sn  spinel  cp  chalcopyrite  sp  sulfides  cu  cuprite  SS  sericite  Cu  native copper  St  strontianite  cv  covellite  tt  tetrahedrite  en  enargite  to  tourmaline  ep  epidote  ur  uraninite  fd  feldspar  wo  wollastonite  fm  ferrimolybdite  ga  galena  gt  garnet  +  high d i p angle  gy hb  gypsum  —  low dip angle  hornblende  he  hematite  jm ko  jamesonite kaolinite  mg  magnetite  gold  bismuth  quartz  ( ) minor amount * producing deposit  frags  fragments  51  CLASSIFICATION An i d e a l c l a s s i f i c a t i o n scheme f o r a metallogenic study c o n c i s e l y describes each deposit i n genetic terms.  Studies on a l a r g e r scale than t h i s  one (e.g., Sutherland Brown, et_ a l . , 1971) generally deal only w i t h producing deposits or important occurrences which have been described i n s u f f i c i e n t d e t a i l to be c l a s s i f i e d g e n e t i c a l l y with reasonable c e r t a i n t y . However, t h i s study deals mainly w i t h occurrences about which l i t t l e i s known; only three can be c a l l e d major producing deposits.  Restrictions  imposed by i n s u f f i c i e n t data have r e s u l t e d i n deposit c l a s s i f i c a t i o n s which are broadly defined and do not n e c e s s a r i l y imply a s p e c i f i c o r i g i n . The c l a s s i f i c a t i o n scheme used i n t h i s study i s o u t l i n e d below. Magmatic Magmatic deposits are i d e n t i f i e d by the presence of massive and/or disseminated copper and n i c k e l s u l f i d e s (commonly c h a l c o p y r i t e and p y r r h o t i t e , r e s p e c t i v e l y ) i n u l t r a m a f i c host rocks.  S u l f i d e s are assumed to have been  derived from the magma; therefore t h e i r age and genesis are s i m i l a r to that of the host rock. Porphyry Porphyry deposits are low-grade accumulations of copper and/or molybdenum s u l f i d e s g e n e t i c a l l y r e l a t e d to t h e i r intermediate to f e l s i c i n t r u s i v e host rocks, but they may a l s o occur i n nearby country rocks.  Metals such  as s i l v e r , gold, zinc and i r o n are uncommonly present i n minor amounts. Sulfides (and rare i r o n oxides) occur as disseminations, i n quartz v e i n stockworks, or i n i n t r u s i v e and/or p i p e - l i k e b r e c c i a bodies. Conventional d e f i n i t i o n s of porphyry deposits ( c f . Sutherland Brown and Cathro, 1976) describe m i n e r a l i z a t i o n associated w i t h p o r p h y r i t i c g r a n i t i c rocks which were emplaced r e l a t i v e l y near the surface; s u l f i d e s formed during the l a t e stages of emplacement and c o n s o l i d a t i o n of the host i n t r u s i o n .  52 Porphyry deposits of the present study include "conventional" porphyries as outlined above and occurrences of s u l f i d e s i n coarse, even-grained  granitic  rocks which probably formed at greater depths than p o r p h y r i t i c g r a n i t i c rocks.  Despite the d i f f e r e n c e i n character of host p l u t o n i c rocks, the  genetic l i n k between s u l f i d e d e p o s i t i o n and l a t e - s t a g e p l u t o n i c events i s probably the same f o r porphyries i n coarse, even-grained and p o r p h y r i t i c , fine-grained host rocks. Skarn Skarn deposits are characterized by c a l c - s i l i c a t e mineral assemblages produced by contact metasomatism mainly i n calcareous rocks near i n t r u s i v e bodies.  M i n e r a l assemblages are diverse and vary considerably w i t h i n and  among deposits.  Chalcopyrite, magnetite and p y r r h o t i t e are the most  commonly reported minerals of economic i n t e r e s t ; garnet, epidote and c a l c i t e are the most commonly recognized gangue minerals. Volcanogenic Volcanogenic deposits i n the study area were produced by submarine exhalative a c t i v i t y which c l o s e l y followed eruption of a c i d i c p y r o c l a s t i c rocks.  Base metal m i n e r a l i z a t i o n i s dominated by p y r i t e , c h a l c o p y r i t e ,  and/or s p h a l e r i t e and galena; gold and s i l v e r enrichments are not uncommon. Quartz i s the dominant gangue mineral, but b a r i t e i s common; large concent r a t i o n s of anhydrite may occur near s u l f i d e s , but r a r e l y w i t h i n s u l f i d e bodies. Since most p o t e n t i a l host rocks i n the study area have undergone deformation, r e c o g n i t i o n of volcanogenic deposits i s d i f f i c u l t , and t h i s may account f o r the i d e n t i f i c a t i o n of only two deposits to date.  Recent  developments of the volcanogenic hypothesis ( c f . Hodgson and Lydon, 1977) make i t c l e a r that p o t e n t i a l environments not r e q u i r i n g p y r o c l a s t i c  53 volcanism''' also e x i s t , but d e t a i l e d information necessary  to recognize such  environments i s seldom a v a i l a b l e . Vein C l a s s i f i c a t i o n of a deposit as a v e i n i s p r i m a r i l y based on the t a b u l a r , commonly discordant nature of the occurrence; an epigenetic, hydrothermal o r i g i n i s assumed f o r a l l v e i n s , although i t i s p o s s i b l e that some tabular syngenetic deposits have been c l a s s i f i e d as v e i n s .  Since veins commonly  are i n t e g r a l constituents of most deposit types, they are described as "veins" only when they appear to be i s o l a t e d and/or unrelated to minerali z a t i o n which may be c l a s s i f i e d more s p e c i f i c a l l y .  Most v e i n deposits are  valued f o r t h e i r precious metal content, but many other metals can be present; quartz i s the most common gangue mineral. Shear 2 Shear deposits occur i n shear zones  as small bodies or disseminations  of s u l f i d e s that are not accompanied by gangue minerals such as quartz and calcite.  P y r i t e , c h a l c o p y r i t e , s p h a l e r i t e and galena are the most commonly  reported s u l f i d e s . This category may overlap somewhat with veins confined to shear zones, but veins are d i s t i n g u i s h e d by being e i t h e r (1) massive, w e l l - d e f i n e d , continuous bodies and/or (2) s m a l l , discontinuous bodies w i t h a considerable amount of gangue minerals.  The d i s t i n c t i o n between v e i n and shear deposits  i s made because the absence of gangue minerals i n shear deposits i s suggestive of an o r i g i n d i f f e r e n t to that of v e i n s ,  whereas veins are commonly  deposited from s t r u c t u r a l l y - c o n t r o l l e d hydrothermal s o l u t i o n s , the o r i g i n of '''The ocean-floor r i f t i n g environment i s a well-known s e t t i n g f o r volcanogenic deposits, but does not occur i n the study area. 2 The term "shear" i s imprecise, as i t does not always imply that shear d i s placement has taken place. A preferred expression i s "a zone of intense f o l i a t i o n , " but the term shear zone i s retained since i t appears abundantly i n the l i t e r a t u r e .  54 shear deposits might be l i n k e d to development of the shear zone as a contemporaneous feature. Development of intense f o l i a t i o n and r e c r y s t a l l i z a t i o n i n host rocks during the formation of a shear zone might cause migration of sparce s u l f i d e components from surrounding rocks i n t o the shear zone where they might accumulate as coarse disseminations or aggregates. Disseminated and Massive These categories are used as d e s c r i p t i v e terms f o r s u l f i d e accumulations which cannot be c l a s s i f i e d as any of the foregoing deposit types due to inadequate d e s c r i p t i v e g e o l o g i c a l data.  Therefore, deposits i n these  categories probably include representatives of other deposit types whose m i n e r a l i z a t i o n i s disseminated or massive i n character.  MAJOR MINES AND RELATED OCCURRENCES Britannia Although only two volcanogenic deposits are reported i n the study area, the 53 m i l l i o n tons of ore produced from B r i t a n n i a make t h i s type of occurrence the most important of a l l .  The other volcanogenic deposit,  Seneca (HSW-13), produced 287 tons i n comparison. Intense deformation and a l t e r a t i o n superimposed  on complex s t r a t i g r a p h y  make i n t e r p r e t a t i o n of the geology of the B r i t a n n i a area d i f f i c u l t .  Although  recent ideas on the o r i g i n of B r i t a n n i a consider the deposit to be syngenetic, most published reports discuss an epigenetic o r i g i n . Geologic Setting and Early I n t e r p r e t a t i o n s Orebodies at B r i t a n n i a are on both limbs and the crest of a major a n t i c l i n e i n a l a r g e northwest-trending shear zone i n a pendant of Lower Cretaceous Gambier Group rocks i n the Coast P l u t o n i c B e l t .  This zone of  shear movement i s the locus of f o l d i n g , f a u l t i n g and the development of  55 intense s c h i s t o s i t y and r e l a t e d a l t e r a t i o n and r e c r y s t a l l i z a t i o n during shear deformation.  Because most s u l f i d e veins p a r a l l e l f o l i a t i o n s i n the  shear zone, early workers interpreted them as introduced along f o l i a t i o n s . Local bedded s u l f i d e s were interpreted as replaced sedimentary beds, and the p o s i t i o n of ore s t r u c t u r a l l y below s l a t e and dacite dike "hoods" was interpreted as a r e s u l t of ore s o l u t i o n s being ponded below impermeable barriers.  B r e c c i a t i o n , f o l d i n g , shearing and s i l i c i f i c a t i o n were looked  upon as ground preparations f o r ore s o l u t i o n s .  The occurrence of bedded  z i n c - r i c h s u l f i d e s i n sedimentary rocks and copper-rich  sulfides i n vol-  canic rocks was interpreted as a r e f l e c t i o n of host rock preference, although an explanation of t h i s preference was not presented. Schofield (1918, 1922, 1926) and James (1929) a t t r i b u t e d the o r i g i n of orebodies to hydrothermal solutions r e l a t e d to i n t r u s i o n of surrounding p l u t o n i c rocks.  On the basis of temperature of formation of mineral  assemblages, I r v i n e (1946) suggested that p l u t o n i c rocks might not be the source of m i n e r a l i z a t i o n , but did not propose an a l t e r n a t e source. Current  Interpretations  In 1969 and 1970, world-wide i n t e r e s t i n the volcanogenic model stimulated r e i n t e r p r e t a t i o n of many deposits hosted by a c i d i c v o l c a n i c and B r i t a n n i a was no exception.  rocks,  Sutherland Brown and Robinson (1970) des-  cribed the r e l a t i o n s h i p between ore deposits and stratigraphy at B r i t a n n i a , and concluded that the ore was volcanogenic i n o r i g i n , dominated by the Keiko ( s t r i n g e r ) v a r i e t y .  A d e t a i l e d study by many Anaconda geologists who  worked at the mine (Payne, et_ al.,  1974) i s the basis f o r the f o l l o w i n g  discussion. Orebodies are i n a d a c i t i c v o l c a n i c center dominated by a complex sequence of v o l c a n i c flows and p y r o c l a s t i c rocks.  During hiatuses i n  d a c i t i c volcanism, a n d e s i t i c sediments were supplied from nearby  centers.  TABLE 3-3, Mac Name  NO.  Type o f D e p o s i t  C-3" Bri tannla  volcanogenic  C-4 Bank o f Vancouver G-6 McVlcar  porphyry  shear (volcanogenic?)  Host Rock. Formation  Gambler Croup  Coaat P l u t o n i c Complex  C a m b l e r Group  CHARACTERISTICS OF DEPOSITS IN THE  BRITANNIA DISTRICT  Mineralized S tructure  Host Rock Type dacltlc volcanic  rocks  massive  a n d e s l t l c t u f f and sedimentary rocks quartz d l o r l t e to q u a r t z monzonite  bodies  Cangue an.ba.qz.gy  al.py.cp  stringers  qz.ca,ba  cp.py  (tt.ga.sl)  breccia pipe with veins, s t r i n g e r s , and mineralized matrix  he.mg.cl.cb.qz  cp.py  (mo,si)  quartz/serlclte schist v e l n l e t s and ( w e l l - f o l i a t e d greenstone t u f f ) disseminations  q*  bedded s u l f i d e s C-l 7 Venus  porphyry  C-21 Roy Group  disseminated  C-22 Ray C r e e k  quartz  porphyry  fracture  Gambler Group  altered, s l l l c l f l e d , p o r p h y r i t i c , tuf faceous a n d e s i t i c greenstone  Gambler Croup  green t u f f a c e o u s s c h i s t  t  Mineralization (ga.ar.po)  p y . c p . s l (ga) ga.sl  fillings  cp,mo  Joints  qz.cl  py  lenses  q«  py.cp  (cp)  shears  cp ( s i )  l e n s e s ; bunches  py .cp  G-31 Irish Molly  r e c r y s t a l l l z e d a p l l t e dike?  porphyry  scld porphyritic l i m e s tone  C-3 2 Bulliondsle  porphyry  G-43 Indian River Copper G-6 2 Horseshoe Roy G-85 Caledonia C-86 ABC Group  d i k e and  Gambier Group  volcanic  rocks  "replacements"  cp.sl  shear shear massive  disseminated  shear  Gambler Group  Cambler Group  lenses  andesitic  greenstone porphyry massive  Cambler Croup  schist  Gambler Group  well-foliated, greenstone  "vein"  q*  py.po ( c p )  q*  cp.py ( s i )  PYiCp schistose disseminations  py.cp  breccia pipe  py .cp  G-89 SUN  porphyry  G-124 Christina C - l 25 Dal No.l C-126 McKlnnon Croup C-133 London  G-152 CaBh  Gambler Group  p a r t l y s c h i s t o s e greenstone and c h l o r i t e s c h i s t  disseminated  Gambler Group  fissile  disseminated  Gambler Group  schist  porphyry  t u f f and  "replacements" p a r a l l e l i n g schistosity  py.cp.sl  cp.sl.py  schist  disseminations  Coast P l u t o n i c Complex ( I n d i a n q u a r t z d l o r l t e River Intrusions)  velnlets  Gambler Croup  slllclfled s h e a r zones w i t h velnlets  chlorlte/sericlte schist  (ga)  i n Joints  py.cp ( s i )  q*  q«  py.cp,sl mo t  57 During one h i a t u s , s u l f i d e s and r e l a t e d bodies of anhydrite were formed. Massive, bedded, z i n c - r i c h orebodies occur i n a n d e s i t i c sedimentary  rocks  above or at the contact with a p a r t i c u l a r u n i t of coarse d a c i t i c t u f f below the sedimentary section.  This coarse d a c i t i c t u f f and the  sedimentary  rocks at the upper contact are host to copper and zinc s u l f i d e s i n s t r i n g e r s and massive bodies. Orebodies were deformed during a major episode of deformation which produced the shear zone and r e l a t e d f o l i a t i o n . along or near l a t e major northwest-southeast  Most orebody contacts are  faults.  An hypothesis based  on removal of cumulative r i g h t - l a t e r a l movement of some 8,000 feet along these f a u l t s allows a r e c o n s t r u c t i o n of s u l f i d e s i n t o two o r i g i n a l orebodies. I f t h i s i s c o r r e c t , a large p o r t i o n of massive l e a d - z i n c - r i c h ore may have been eroded; t h i s hypothesis explains why s t r i n g e r - t y p e copper s u l f i d e s are more abundant than normally would be expected to be associated with the present amount of massive zinc and copper-zinc ore. S u l f i d e Occurrences Outside the B r i t a n n i a Shear Zone (Table  3-3)  Descriptions of mineral occurrences i n the B r i t a n n i a pendant are reminiscent of early reports on the B r i t a n n i a orebodies. massive m i n e r a l i z a t i o n : G-77 abundant s p h a l e r i t e ; G-6  Two deposits report  i s a massive c h a l c o p y r i t e body with l e s s  (McVicar) contains massive, bedded, s p h a l e r i t e - r i c h  ore w i t h galena and s t r i n g e r - t y p e copper-zinc s u l f i d e s .  Other deposits  hosted by s c h i s t o s e , a n d e s i t i c , v o l c a n i c rocks commonly are described as disseminations, lenses and v e i n l e t s p a r a l l e l to s c h i s t o s e f a b r i c s ; s u l f i d e s include p y r i t e , c h a l c o p y r i t e , s p h a l e r i t e and rare galena. Figure 2-1 shows the l o c a t i o n of these deposits near a poorly-defined shear zone s u b - p a r a l l e l to and east of the B r i t a n n i a shear zone.  Host  rocks are undeformed d a c i t i c flows and p y r o c l a s t i c u n i t s , many of which contain abundant disseminated p y r i t e ( J . G. Payne, personal communication,  58 1978).  James, 1929, considered the absence of b a r i t e , anhydrite and the  " B r i t a n n i a S i l l s " (dacite dikes) i n t h i s area to be s i g n i f i c a n t i n d i c a t i o n s of unfavorable conditions f o r m i n e r a l i z a t i o n .  However, b a r i t e i s not  abundant at B r i t a n n i a , anhydrite i s leached r e a d i l y from surface rocks, and the " B r i t a n n i a S i l l s " are now believed to be post-ore.  The most reasonable  hypothesis regarding the o r i g i n of these deposits i s that they are the same age and type as the B r i t a n n i a orebodies. Porphyry deposits i n the B r i t a n n i a d i s t r i c t are e i t h e r associated with the "Indian River i n t r u s i o n s " near the eastern shear zone (G-31,32,133), or near the B r i t a n n i a shear zone, j u s t outside the l i m i t s of the pendant (G-4,17,89).  The Indian River i n t r u s i o n s are believed to be l a t e a c i d i c  phases of the Coast P l u t o n i c Complex which intrude pendant rocks (James, 1929).  Copper and l o c a l molybdenum s u l f i d e s i n these porphyries are sparce.  More abundant m i n e r a l i z a t i o n i s located i n i n t r u s i v e b r e c c i a pipes i n p l u t o n i c rocks (G-4,89) at the southeastern end of the B r i t a n n i a shear 3 zone.  Age of m i n e r a l i z a t i o n corresponds to l a t e stage a c t i v i t y of i n t r u d i n g  plutons, i n Upper Cretaceous  time.  Northair High-grade v e i n m i n e r a l i z a t i o n a t Northair was discovered i n 1969; production began i n 1976, and continues to make t h i s mine the only operating one i n the study area.  Reserves as of May, 1977, are estimated at 330,637  tons, averaging 0.4 ounces/ton gold, 4.6 ounces/ton s i l v e r , 2.7 percent lead and 4.0 percent z i n c . Description S u l f i d e s occur, i n three oner-to-f orty^-f oot-wide, northwesterly-trending, 3 Veins of massive c h a l c o p y r i t e a l s o occur i n p l u t o n i c rocks i n t h i s v i c i n i t y (J, G. Payne, personal communication, 1978), but d e s c r i p t i o n s of s p e c i f i c l o c a l i t i e s are not a v a i l a b l e .  59 v e r t i c a l , more-or-less tabular sheets which appear to be o f f s e t by n o r t h e r l y - t r e n d i n g , s u b - v e r t i c a l f a u l t s (refer to Figure 3-2).  Vein  minerals include p y r i t e , s p h a l e r i t e and galena, and minor amounts of c h a l c o p y r i t e , n a t i v e gold, p y r r h o t i t e and various s i l v e r minerals (argent i t e , t e t r a h e d r i t e , stromeyerite) i n a quartz-carbonate gangue.  Quartz and  c a l c i t e e x h i b i t deformation t e x t u r e s ; s u l f i d e s and gangue i n part appear to 4  be r e c r y s t a l l i z e d .  No hydrothermal a l t e r a t i o n r e l a t e d to the v e i n has been  recognized. The three s u l f i d e bodies, c a l l e d (northwest to southeast) the Discovery, Warman and Manifold Zones, are d i s t i n g u i s h e d from each other by metal r a t i o s , metal contents and t e x t u r e s , summarized i n Table 3-4. Enclosing rocks are considered equivalent to the Lower Cretaceous Gambier Group, although t h i s c o r r e l a t i o n i s tenuous, as discussed i n Chapter Two.  The southern p o r t i o n  of the pendant contains a 5,000-meter s e c t i o n of homoclinal, n o r t h e r l y trending, v e r t i c a l or steeply east dipping, a n d e s i t i c to r h y o l i t i c , f r a g mental v o l c a n i c rocks i n c l u d i n g coarse agglomerates and f i n e - g r a i n e d ( M i l l e r , et: a l . , 1978).  tuffs  Where present, s c h i s t o s i t y and f a u l t s commonly are  s u b - p a r a l l e l to bedding i n v o l c a n i c rocks, so that northwesterly-trending veins cross-cut the s t r u c t u r a l g r a i n of the host rock. A K/Ar date of 124 + 4 Ma was obtained from hornblende i n an i n t r u s i v e rock believed to be a feeder f o r surrounding hornblendic c r y s t a l t u f f s s t r a t i g r a p h i c a l l y below mineralized agglomerates ( J . H. M i l l e r , personal communication, 1977).  However, the i n t r u s i o n may post-date tuffaceous rocks.  A whole rock K/Ar date of 74 Ma on f o l i a t e d greenstone adjacent to s u l f i d e bodies ( L i t t l e , 1974) i n d i c a t e s that greenschist metamorphism of pendant rocks, i n t r u s i o n of plutons, and/or v e i n emplacement might have occurred at ^Strained cleavage i n c a l c i t e and undulatory e x t i n c t i o n i n quartz were noted by the w r i t e r ; s u l f i d e s and gangue minerals form an e q u i l i b r i u m texture with common 120° g r a i n boundaries.  s  s  s . Discovery Zens S  Manhole! Zone  s S  1  S  s  «.  S  War man Zone f  s /  ^  —  s  /  < l  s  \  s LEGEND  s Sll  — »  mine, tuorWus^t  —  fault 0  JSO  iat  /fs  if*  m«.t>ar>  Figure 3-2.  R e l a t i v e p o s i t i o n s of the three main mineralized zones and f a u l t s at Northair Mines ( a f t e r Dickson and McLeod, 1975, and M i l l e r , et a l . , 1978). o  TABLE 3-4.  CHARACTERISTICS OF THE NORTHAIR SULFIDE BODIES  As!  Cu  Pb  Discovery Zone  ,55  5.43%  6.58%  ,10 oz/T  1.18 oz/T  massive ( l o c a l l y banded) and v e i n l e t s  Warman Zone  ,24  1.45%  2.39%  ,68 oz/T  .85 oz/T  massive, disseminated and veins  Manifold Zone  .07  ,28%  ,57%  .28 oz/T  14.48 oz/T  from M a n i f o l d , 1976 "from M i l l e r , et a l . , 1978  J  Zn  Au  Texture  veins and disseminated (considerable quartz and carbonate gangue)  62 t h i s time (or e a r l i e r ) . Genesis As s c h i s t o s i t y and f a u l t i n g are p a r a l l e l to the l a r g e - s c a l e o u t l i n e of the pendant, they are believed to be r e s u l t s of the i n t r u s i o n of surrounding p l u t o n i c rocks, and therefore m i n e r a l i z a t i o n which i s cut by these structures pre-dates i n t r u s i o n i n the v i c i n i t y (M. P. Dickson, personal communication, 1975).  Although Northair i s a tabular body which geometrically resembles a  v e i n , metal and host rock associations are suggestive of a volcanogenic origin.  Two major f a c t o r s must be c l a r i f i e d before the volcanogenic hypo-: .  thesis of o r i g i n can be applied w i t h c e r t a i n t y . 1)  Small-scale deformation of the v e i n should be demonstrated to be equivalent ( i . e . , p a r a l l e l ) to deformation of the host rock.  2)  I f s u l f i d e s (and gangue?) have not been transported f a r , they should be s p a t i a l l y r e l a t e d to a s t r a t i g r a p h i c - t i m e horizon i n the v o l c a n i c host rock. I f massive portions of the v e i n are o r i g i n a l syngenetic accumulations ( M i l l e r , et a l . , 1978), t r a n s p o r t a t i o n could not have been great.  If s u l f i d e s at N o r t h a i r are not stratabound, but c r o s s - c u t t i n g , as suggested by Manifold (1976), an epigenetic o r i g i n must be envisioned. However, i f s u l f i d e m i n e r a l i z a t i o n was syn- or post-deformation synchronous w i t h i n t r u s i o n of the Coast P l u t o n i c Complex, vein-forming hydrothermal solutions would be expected to f o l l o w s t r u c t u r a l trends of the host rock."' Since m i n e r a l i z a t i o n cross-cuts f o l i a t i o n s , an epigenetic v e i n would have to have been emplaced a f t e r d e p o s i t i o n of the host rock and before deformation.  I f host rocks are Lower Cretaceous, the a v a i l a b l e time i n t e r v a l f o r  epigenetic m i n e r a l i z a t i o n i s minimal, since Coast P l u t o n i c Complex K/Ar dates and Gambier Group d e p o s i t i o n overlap i n the upper Lower Cretaceous. ^The conclusion that post-deformational hydrothermal f l u i d s would follow p r e - e x i s t i n g planes of weakness i s based on the knowledge that b a s a l t dikes i n the mine area that feed o v e r l y i n g Quaternary flows do f o l l o w s c h i s t o s i t y .  63 I t appears that i f one i s to consider epigenetic hydrothermal m i n e r a l i z a t i o n , the age of the host rock must be examined more c l o s e l y .  I f host rocks are  of the Upper T r i a s s i c Pioneer Formation, v e i n m i n e r a l i z a t i o n i s more e a s i l y reconciled w i t h the a v a i l a b l e data. Two a d d i t i o n a l points of i n t e r e s t regarding a supposed volcanogenic o r i g i n are the f o l l o w i n g : 1)  Carbonate i s not usually reported i n great q u a n t i t i e s from volcanogenic d e p o s i t s , and yet i t accounts f o r h a l f the gangue at N o r t h a i r . Perhaps the carbonate i s not a byproduct of m i n e r a l i z a t i o n , but represents a calcareous horizon i n the host rock that may have helped l o c a l i z e s u l f i d e s ( M i l l e r , et a l . , 1978).  2)  An environment d i s t a l from the source vent i s suggested by lack of s t r i n g e r zones and very low copper values. This environment i s considerably d i f f e r e n t from that of other volcanogenic deposits i n the study area ( B r i t a n n i a , G-3; Seneca, HSW-13) which are copper-rich w i t h abundant stringer mineralization.  I t i s not p o s s i b l e at t h i s time to do much more than speculate on the o r i g i n of m i n e r a l i z a t i o n at N o r t h a i r . A v a i l a b l e information suggests to the w r i t e r that the deposit i s a v e i n , but the o r i g i n of that v e i n i s questionable, as i s the presence of syngenetic m i n e r a l i z a t i o n .  S u l f i d e s were  probably o r i g i n a l l y volcanogenic accumulations, but u n t i l more data are presented to c l a r i f y c e r t a i n r e l a t i o n s h i p s discussed above, the deposit cannot be categorized as volcanogenic i n nature. Formation of v e i n m i n e r a l i z a t i o n , i f epigenetic or remobilized syngenetic, would have occurred i n Upper Cretaceous time during i n t r u s i o n of surrounding plutons.  I f s u l f i d e s are deformed syngenetic d e p o s i t s , they  would have formed i n Lower Cretaceous time, if_ host rocks belong to the Gambier Group. Unpublished data i n d i c a t i n g the presence of disseminated s u l f i d e s i n bedded carbonate and the f a c t that portions of the deposit consist of m u l t i p l e veins suggest to current i n v e s t i g a t o r s that the deposits cannot be considered a v e i n , but a d i s t a l volcanogenic deposit ( S i n c l a i r , personal communication, 1978).  64 Other Deposits i n the Northair D i s t r i c t (Table Occurrences  3-5)  i n the Northair D i s t r i c t are hosted by p l u t o n i c and meta-  volcanic rocks; the l a t t e r are contained i n two n o r t h e r l y - t r e n d i n g pendants of Gambier (?) Group rocks surrounded by i n t r u s i v e rocks (Figure 2-1). Veins, disseminations, shears, skarns and porphyries are present. The four deposits i n the western or Callaghan Creek pendant (J-45,51, 151,152) are m i n e r a l o g i c a l l y s i m i l a r to N o r t h a i r , and therefore might be related genetically.  Disseminated lead-zinc-copper m i n e r a l i z a t i o n i n  s t r i n g e r s and disseminations i s accompanied uncommonly by  quartz-carbonate  gangue and may be l o c a l i z e d along shear zones i n a n d e s i t i c greenstone hosts. One deposit (J-51, Blue Jack or S i l v e r Tunnel) i s p o s s i b l y syngenetic, and has been deformed (Woodsworth, et a l . , 1977).  D e f i n i t i o n of a m i n e r a l i z i n g  episode f o r the remaining deposits i s not f e a s i b l e ; both Lower Cretaceous deposition of host rocks and Upper Cretaceous i n t r u s i o n of nearby plutons are p o t e n t i a l m i n e r a l i z i n g events. M i n e r a l i z a t i o n i n and around the eastern pendant d i f f e r s considerably from that of the Northair pendant.  Although both pendants are proposed to  be of the same formation, the eastern pendant contains very l i t t l e known lead-zinc m i n e r a l i z a t i o n .  Aside from one galena and b a r i t e v e i n i n green-  stone (J-150), deposits i n the eastern pendant are e i t h e r skarns i n pendant rocks (J-42,67), or porphyries i n i n t r u s i o n s (J-49,50,134).  Skarn and  porphyry deposits formed during i n t r u s i o n of p l u t o n i c rocks i n Upper Cretaceous  time.  Giant Mascot Giant Mascot (also P r i d e of Emory, P a c i f i c N i c k e l ) i s the only occurrence of magmatic n i c k e l and copper i n the area which ever produced; 6.0 m i l l i o n tons of ore were mined.  TABLE 3-5. Mac No. Kane .1-42 London  Type o f Deposit  'skarn  Host Rock Formation  CHARACTERISTICS OF DEPOSITS IN THE NORTHAIR DISTRICT Mineralized Structure  Host Rock Type  Coast P l u t o n i c Complex  quartz/sericite schist (well-foliated granodiorite)  Gambier(?)Group  metabasalt  Gambier(?)Group  andesite;  Attitude  Gangue  ca skarn zone  Mineralization  cp.ml.py  ep,mg,ca,qz  * J-45 Astra, Cambria  disseminated  diorite  stringers  N35W.65SW  qz.cb  J-49 Azure  porphyry  Coast P l u t o n i c Complex  quartz/sericite schist (well-foliated granodiorite)  s t r i n g e r s and lenses  qz  J-50 Elk  porphyry  Coast P l u t o n i c Complex  granite  f r a c t u r e s and shears  ss,cl qz  shear  Gambier(?)Group  muscovite/chlorite  * J-51 Blue  schist  Jack  Fitzsimmons J-67  lenses, streaks and disseminations i n shear zone  Gamb i e r ( ? ) G r o u p  J-131 CI.JE  vein  Coast P l u t o n i c Complex (?)  vein  Coast P l u t o n i c Complex  disseminations  J-134 RM J-150 (occurrence)  disseminated  porphyry  vein  (qz,ca) ga,sl,py,cp,Au,tt  ep,cb,gt  vein  p y r o c l a s t i c andesite  vein  ml,cp,mo,py  N-S.65W  skarn  J-!30* Northair  J-132 CI.JE'  cp.py (ral.az)  t  v a i l rock  ga,sl,cp,py  N55W, + N  qz, cb  qz  p y . s l . c p (ga.mg)  py.ga.sl.cp  cp  cp,ml  meta-diorite  shear zone  Gambier(?)Group  greenstone  vein v e l n l e t s and shear zones  ga.sl  small fractures  Cu,Ag,Zn  J-151 Kay  disseminated  Gambier(?)Group  a n d e s i t i c v o l c a n i c rocks  J-152 ' TMC No.l  disseminated  Gambier(?)Group  a n d e s i t e ; minor quartz diorite  NW  cp.py  ba  ga  (cp)  66 Nature and O r i g i n of U l t r a m a f i c Rocks The Giant Mascot U l t r a m a f i t e i s a unique e l l i p t i c a l ,  crudely-zoned  body (Figure 3-3) which does not f i t i n t o most e x i s t i n g c l a s s i f i c a t i o n schemes ( c f . N a l d r e t t and C a b r i , 1976).  The dominance of orthopyroxene i n  u l t r a m a f i c and n o r i t i c rocks and the presence of magmatic s u l f i d e s are the major features which d i s t i n g u i s h the Giant Mascot U l t r a m a f i t e from "Alaskantype" zoned u l t r a m a f i c i n t r u s i o n s . Several steeply-dipping, p i p e - l i k e cores of p e r i d o t i t e and l e s s common dunite are surrounded by s u b s t a n t i a l amounts of pyroxenite (hornblendic and b r o n z i t i c ) ; e r r a t i c zones of hornblendite occur along the periphery of the main u l t r a m a f i c body.  N o r i t e and d i o r i t e are the major f e l d s p a t h i c i n t r u -  s i v e rocks surrounding the u l t r a m a f i c body. S i m i l a r pyroxenes i n u l t r a m a f i c and d i o r i t i c rocks have l e d authors (Cockfield and Walker, 1933; Horwood, 1936; Aho, 1956; and Peach, i n C l a r k , 1969) to the conclusion that d i f f e r e n t i a t i o n of an orthopyroxene-rich magma produced p r o g r e s s i v e l y l e s s mafic i n t r u s i v e phases.  K/Ar dates (McLeod,  et a l . , 1976) i n d i c a t e that u l t r a m a f i c rocks (119-95 Ma) cooled s h o r t l y before d i o r i t i c phases (79-89 Ma).  Cumulate textures suggested to McLeod  (1975) that the o r i g i n a l d i f f e r e n t i a t i n g magma was crudely s t r a t i f o r m before re-emplacement as a " c r y s t a l mush." Mineralization P y r i t e , p e n t l a n d i t e , c h a l c o p y r i t e , p y r r h o t i t e and magnetite occur i n three types of orebodies:  zoned, massive and v e i n - l i k e .  Zoned orebodies  of disseminated s u l f i d e s occur w i t h i n the pipe s t r u c t u r e s r e f e r r e d to above. The presence of s u l f i d e s i s a f u n c t i o n of rock type, as dunite and p e r i d o t i t e cores commonly contain s u l f i d e s , pyroxenites l e s s commonly so, and hornblendite rarely.  N o r i t e contains rare disseminated s u l f i d e s .  S u l f i d e and  67  + + 4  -r +  '-I-  +  fi- + •+ + + + + + •  +- + + + + 4- H»K|^+ -tt'  +  +  ^  +  +,  •-0',U\\V iL E G E N D :  ::-:-|  EZ3  KAN  OP  +  \\V »  If I, + +'<•  +  ;  |::  , + + + + + + ,+ + + •+ -+*i(• l.;'U  +.+  "A t(+ +^'-<';.^^"f^.*;v.S-S'V  + + + + + + + + + * + + + + -*- \<+N«? + + + +;+.+,+  +  + P"l  D O I P T ' C O V C Q C D  HOMtUEMOlTt PVQO«tMITt  JW.VJ  PV»0» •>•!•«,  E2E3  PcniooriTC.  •UftFACt  GEOLOGY AND  MINERALIZATION PACIFIC  Figure 3-3.  NICKEL  MINES  S C A L E  tOOO  O P  F " C C T  SOOO  4QQd  3000  O N I MILK  Surface geology of the Giant Mascot Ultramaflte (from Aho, 1956).  68 rock type r e l a t i o n s h i p s are not c o n s i s t e n t ; a s u l f i d e - r i c h rock type i n one orebody may be barren i n another.  N i c k e l to copper r a t i o s are highest  i n the cores of zoned orebodies, decreasing outwards as t o t a l s u l f i d e con-^ tent decreases. Massive orebodies are s i m i l a r m i n e r a l o g i c a l l y to zoned ones, but are i r r e g u l a r i n form, and commonly show evidence of movement or r e m o b i l i z a t i o n through b r e c c i a t i o n , l a r g e - s c a l e p r o t o c l a s t i c t e x t u r e s , or flow-banding. Sharp contacts are c h a r a c t e r i s t i c of massive orebodies, but some grade i n t o zoned orebodies. V e i n - l i k e s u l f i d e s w i t h lower n i c k e l to copper r a t i o s than e i t h e r zoned or massive orebodies occur i n a l l rock types, but are economic only where e n r i c h i n g l a r g e r orebodies.  These veins can probably be a t t r i b u t e d  to l a t e - s t a g e m o b i l i z a t i o n of e x i s t i n g s u l f i d e bodies. The o r i g i n of m i n e r a l i z a t i o n at Giant Mascot remains as much of a dilema as the o r i g i n of the u l t r a m a f i c host rocks.  C o c k f i e l d and Walker  (1933) favored a hydrothermal o r i g i n f o r the s u l f i d e bodies; McTaggart (1971) favored a metasomatic o r i g i n f o r the pipes by f r a c t u r e - c o n t r o l l e d f l u i d s , and Aho (1956) proposed high-temperature metasomatic and magmatic o r i g i n s for pipe and massive orebodies, r e s p e c t i v e l y .  Cairnes (1924), Horwood (1936)  and McLeod (1975) favored a magmatic o r i g i n i n v o l v i n g segregation and subsequent i n j e c t i o n of s u l f i d e s .  McLeod (1975) supported h i s view by demon-  s t r a t i n g that pyroxene p a i r s from assorted rock types i n the u l t r a m a f i c body e q u i l i b r a t e d at a mean minimum temperature of 990°C. Although d e t a i l e d knowledge of the processes involved i s l a c k i n g , a complex magmatic o r i g i n i s accepted here f o r the u l t r a m a f i c body and i t s contained s u l f i d e s .  Age of s u l f i d e formation, 108 + 4 Ma (McLeod, 1975),  corresponds to that of mineralized hornblendite i n one of the orebodies.^ I t i s important to consider the s i g n i f i c a n c e of t h i s date (and others i n  69 Occurrences Outside the Giarit Mascot U l t r a m a f i t e (Table 3-6) As mentioned i n Chapter Two, the Giant Mascot U l t r a m a f i t e i s s p a t i a l l y associated w i t h a b e l t of u l t r a m a f i c rocks near the northern extension of the Shuksan Thrust.  The l a r g e s t u l t r a m a f i c body i s on Old S e t t l e r Mountain,  i n the southern p o r t i o n of the b e l t .  Described by Lowes (1972) as a t y p i c a l  alpine-type u l t r a m a f i t e , i t i s mainly dunite and contains no s u l f i d e s . Smaller bodies north of Old S e t t l e r Mountain, i n the Cogburn Creek area, are s i m i l a r to Giant Mascot (HNW-38,39,40,41,42).  Pyroxenite and hornblende-  pyroxenite, mineralized s p a r i n g l y by massive and disseminated p y r i t e , p y r r h o t i t e , c h a l c o p y r i t e and rare p e n t l a n d i t e , are c l o s e l y associated w i t h Spuzzum d i o r i t e i n these deposits.  Orthopyroxene i s of secondary abundance  compared to clinopyroxene i n these occurrences.  S i m i l a r i t i e s to Giant  Mascot suggest that m i n e r a l i z a t i o n at Cogburn Creek was contemporaneous with that at Giant Mascot. Other magmatic deposits commonly are associated s p a t i a l l y with major f a u l t s , implying an o r i g i n l i n k e d to movement along these deep-seated c r u s t a l breaks.  HSW-5 and HNW-52 are near the Hope F a u l t , and outside the  Giant Mascot D i s t r i c t , HNW-34, HSW-118 and HSW-125 are near the Hozameen Fault.  M i n e r a l i z a t i o n i s presumed to have occurred during f a u l t i n g when  access to mantle (?) sources was obtained.  MINING CAMPS WITHOUT MAJOR MINES Camps or d i s t r i c t s discussed i n t h i s s e c t i o n stand out as areas of r e l a t i v e l y high concentrations of m i n e r a l prospects.  Regardless of pro-  duction, i f any, they have generally boasted of enough mineral occurrences the Spuzzum P l u t o n i c B e l t ) i n l i g h t of the f a c t that high pressure and temperature metamorphism discussed i n Chapter Two might have a f f e c t e d argon r e t e n t i o n i n these rocks. Thus the reported age of the Giant Mascot U l t r a mafite and i t s s u l f i d e s might be younger than the a c t u a l age which might pre-date metamorphism and/or i n t r u s i o n of the Spuzzum and Scuzzy plutons.  TABLE Mac No. Name  Type o f Deposit  3-6.  Host Rock Formation  CHARACTERISTICS OF DEPOSITS IN THE GIANT MASCOT DISTRICT  Host Rock Type  Mineralized Structure  Gangue  Mineralization  HSW-4 Giant Mascot  magmatic  HSW-5 Bea  magmatic  ultramafic  HSW-111 Suede  magmatic  pyroxenite; p e r i d o t i t e  disseminated po.cp.py  HNW-38 AL  magmatic  f r a c t u r e d and s i l i c i f i e d m a f i c - r i c h rocks i n bands and l e n s e s quartz d i o r i t e  massive py.po (cp.pt)  HNW-39 occurrence  magmatic  hornblende  pervas i v e po.cp.py  HNW-40 occurrence  magmatic  pyroxenite  HNW-41 occurrence  magmatic  hornblende~pyroxenite  HNW-42 occurrence  magmatic  HNW-45 Victor  G i a n t Mascot . Ultramaflte  Spuzzum P l u t o n  massive; disseminated po.pt,cp.py  p i p e - l i k e bodies  pyroxenite  disseminated cp  amphibolite ( ? )  massive; disseminated py (po.cp)  pyroxenite  disseminated cp.po  amphibolite  disseminated py.po,cp  magmatic Spuzzum P l u t o n  HNW-52 Citation  p e r i d o t i t e ; hornblende p y r o x e n i t e ; dunite  magmatic  meta-quartz d i o r i t e  near gabbro/pyroxenite  contact  minor  p e r i d o t i t e (?)  disseminated po, cp  s c h i s t ; amphibolite  Cu.Ni.Zn  O  71 to have a t t r a c t e d considerable e x p l o r a t i o n i n t e r e s t .  Locations of a l l  camps are shown i n Figure 3-1. Eagle B e l t (Table 3-7) Two d i s t i n c t types of mineral occurrences are present i n the Eagle Belt.  Copper, z i n c and lead s u l f i d e s occur as disseminations (HNW-22,23)  and i n a v e i n (HNW-24). Molybdenum and copper s u l f i d e s occur i n porphyry deposits i n b r e c c i a bodies (HNW-28,54) and a dike (HNW-31). Assuming the b r e c c i a bodies and dike are r e l a t e d to l a t e stages of plutonism i n the Eagle Complex, d e p o s i t i o n of s u l f i d e s i s contemporaneous w i t h the formation of t h i s complex i n J u r a s s i c or Lower Cretaceous time.  The age of copper-  z i n c - l e a d deposits i s more d i f f i c u l t to determine, as the mineral assemblage i s not c h a r a c t e r i s t i c of s u l f i d e deposits associated w i t h p l u t o n i c rocks, and the nature of non-plutonic rocks i n the v i c i n i t y i s uncertain. Summit Camp (Table 3-8) F a u l t - c o n t r o l l e d m i n e r a l i z a t i o n of the Summit Camp on Treasure Mountain has been explored and worked i n t e r m i t t e n t l y since 1894 when the Eureka claim was located.  Veins and s t r i n g e r zones from one inch to f i v e feet wide con-  t a i n p y r i t e , s p h a l e r i t e , and galena, w i t h minor amounts of t e t r a h e d r i t e , p y r r h o t i t e , c h a l c o p y r i t e , s t i b n i t e , quartz, c a l c i t e and s i d e r i t e .  The most  common occurrences are t h i n s u l f i d e v e i n l e t s , with or without gangue, that occupy a much wider f r a c t u r e zone composed of a l t e r e d country rock w i t h , perhaps, some gouge. Fault zones are nearly perpendicular to bedding, and s u l f i d e s are found e r r a t i c a l l y along them.  Ten of the twelve deposits i n the Summit Camp occur  i n Lower and Middle J u r a s s i c Ladner Group v o l c a n i c and sedimentary rocks. The remaining two are i n Lower Cretaceous Pasayten sedimentary rocks. D i s t r i b u t i o n between these host rocks appears to be a f u n c t i o n of the amount  TABLE Mac No. Name HNW-22 Mag Group HNW-23 Ly,Ford, Snow,Dora HNW-24 Coldwater  1^-28 JM.SEC  Type o f D e p o s i t  Host Rock Formation  disseminated  Eagle- Complex  disseminated  vein  porphyry  3-7.  CHARACTERISTICS OF DEPOSITS IN THE EAGLE COMPLEX  Host Rock Type  Mineralized Structure '  intrusive breccia a l t e r e d porphyry  fractures;veins disseminations  E a g l e Complex  a l t e r e d porphyry ( q u a r t z monzonite o r quartz d i o r i t e )  zone o f disseminations  E a g l e Complex  a l t e r e d q u a r t z monzonite vein l i m e s t o n e and r h y o l i t e near g r a n o d i o r i t e fractures  Width  150'  breccia  p i p e (?) a l t e r a t i o n halo around d i k e w i t h stringers a l t e r e d area near b r e c c i a pipe with phyllic alteration  porphyry  E a g l e Complex  granitic, pbrphyritic dike intruding granodiorite  HNW-54 Mod Bar  porphyry  E a g l e Complex  r h y o d a c i t e porphyry  Gangue  Mineralization py.cp.sl py.cp.sl  E a g l e Complex  EKH-31 Gossan  Attitude  NW.50NE  N40E.70NW  p y . s l . g a (cp)  qz (cb) qz  p y , g a , s l , t t (cp) sl.ga  mo (cp)  qz  (qz)  py  (cp.mo)  py,cp.mo,cu,en,cc  . N3  TABLE Mac No. Name  Type o f D e p o s i t  Host Rock Formation  HSW-16 . S i l v e r Chief  vein  Pasayten Group  HSW-18* Eureka  vein  Ladner Group  HSW-19 Southern No. 8 Fr.  vein  Ladner Group  HSK-20 Bluebell  vein  Ladner Group  HSW-21 Queen Bess  vein  Ladner Group  HSW-22 Indiana  3-8.  CHARACTERISTICS OF DEPOSITS IN THE SUMMIT CAMP Mineralized Structure  Host Rock Type a r g i l l i t e , arkose and conglomerate  fault  zone  v e i n along f a u l t v e i n along d i k e  a r g i l l i t e , breccia and conglomerate  vein  agglomerate and black a r g i l l i t e  bedded quartz velnlets  a r g i l l i t e , breccia and conglomerate  vein f r a c t u r e zone stringers v e i n along f a u l t  Width  l"-20'  N50E.65SE N70E.65SE  4"-12" 18"  N45E N70E  4"-6" up t o 19"  l'-3' 6"  vein  Ladner Group  t u f f , breccia'and argillite  stringers i n 20' zone  vein  Ladner Group  shear  HSW-46 Blackjack  shear  HSW-47 H a l l ' s Group  shear  Ladner Group  ESW-66 Rainy  shear  Pasayten Group  c o n t a c t o f porphyry and q u a r t z i t e massive agglomerate, t u f f and a r g i l l i t e  stringers  Ladner Group  qz.ca  ga.sl.cp  N20E, +E  cb ,qz  ga.sl.cp.py  N20E.50SE  qz  sb  qz,gouge qz  sl,ga,py (sp.Mn)  qz  sl.ga.py sp.py (Mn)  SW,N WSW SW.NW N65E, +  py.sl.ga  l"-6"  coarse b l a c k d i k e  Ladner Group  q u a r t z i t e with p y r i t i c bands a r g i l l i t e and conglomerate t u f f and massive a n d e s i t e  seam dike walls  N75E.70SE  gouge, rock frags (qz.cb)  N60K  po.sp  15"  N70E.70SE  rock frags,?  ?  N33E  rock frags  py.ga.sl  rock frags  py.ga.sl sl.ga  10"-12" 20'  r u s t y bed bedded gouge seam  py py.si  shears and fractures vein stringers i n f r a c t u r e zone  ga.sl.py  6'-8'  2'-4'  Ladner Group  vein  vein  Mineralization  s l , g a , p y , c p , t t (Mn)  massive b r e c c i a and agglomerate; t u f f contacts o f d i k e and a r g i l l i t e  HSW-45 U.S. Rambler  HSW-85 Morning S t a r  Gangue  qz,cb,sd  1"-1'  17" ESW-23 Summit  Attitude  sl,po,py,cp 3"-4" 5'  E-W.40S N60E  qz,rock frags  ga,tt,cp  74 of f a u l t i n g , since of the f i v e recognized  f a u l t s i n the camp, only one has  been traced i n t o the Pasayten Group. Two reports of host rock preference  from d i f f e r e n t deposits i n t h i s  camp c o n f l i c t as to whether a r g i l l i t e i s associated with r i c h or poor mineralization.  Host rock c o n t r o l , therefore, i s assumed to be minimal.  Rock  type hosts include q u a r t z i t e , agglomerate, t u f f , b r e c c i a , conglomerate, arkose and a r g i l l i t e . Old reports commonly a t t r i b u t e the source of s u l f i d e s to a p o r p h y r i t i c dike which intrudes the Treasure Mountain f a u l t zone and commonly separates mineralized zones i n t o hanging- and f o o t w a l l portions.  However, the main  r e l a t i o n s h i p between t h i s dike and m i n e r a l i z a t i o n i s that both intruded the weak f a u l t zone; dike and s u l f i d e s commonly are independent of each other. Sulfides occur i n f a u l t s that o f f s e t the Chuwanten, d e f i n i n g t h e i r age as post-86 Ma. The only known post-86 Ma events nearby that might be responsible f o r m i n e r a l i z a t i o n are i n t r u s i o n of the Needle Peak Pluton and extrusion of the Coquihalla Group (Figure  2-1).  Jim K e l l y Creek Camp (Table 3-9) Aside from minor differences between mineral assemblages, prospects at Jim K e l l y Creek are s i m i l a r to those of the Summit Camp on Treasure Mountain. Deposits i n f r a c t u r e zones consist of veins and quartz s t r i n g e r s up to one foot wide i n zones up to 20 feet wide.  Veins contain p y r i t e , galena,  s p h a l e r i t e , c h a l c o p y r i t e , and minor amounts of t e t r a h e d r i t e and c h a l c o c i t e ; quartz gangue i s reported i n every occurrence.  The deposits are i n schistose  metavolcanic rocks of the N i c o l a Group which were a f f e c t e d by Late Cretaceous movement along the Pasayten F a u l t . S i m i l a r i t i e s i n form and mineralogy between Jim K e l l y Creek and Summit  TABLE Mac No. Name HSW-48 Gold Mtn.  Type o f Deposit  vein  3-9.  Host Rock Formation  N i c o l a Group  CHARACTERISTICS OF DEPOSITS IN THE JIM KELLY CREEK CAMP  Host Rock Type  metavolcanic  Mineralized Structure  schist  vein faults  HSW-49 Superior  vein  N i c o l a Group  schist  Attitude  2"-12"  N90E, S  offsetting vein  N-S  vein i n fracture zone 4'-6'  HSW-50 John B u l l  vein  N i c o l a Group  metavolcanic and minor sedimentary schist  HSW-51 Marsellaise  vein  N i c o l a Group  schist  f r a c t u r e zone with stringers  vein  N i c o l a Group  schist  f a u l t zone  HSW-52 Spokane  Width  vein  cross-fractures  \  6"-10"  qz  gouge  qz, rock frags  N7E.45NW  3' 20*  Gangue  Mineralization  ga,py,cp,ap,tt  minor  ga,py,cp,tt  py.cp  qz N68W.35SW  qz  py.cp low grade  76  Camp suggest s i m i l a r modes and time of formation.  As the Coquihalla Group  i s only four kilometers north of Jim K e l l y Creek, i t i s suggested that volcanism provided heat and/or s o l u t i o n s and/or metals which migrated i n t o f r a c t u r e zones and deposited s u l f i d e - r i c h veins. Ladner Gold B e l t (Table  3-10)  Unlike most v e i n deposits i n the study area whose l o c a l i z a t i o n i s generally unpredictable, veins i n the Ladner gold b e l t occur c o n s i s t e n t l y along the serpentine b e l t which marks the Hozameen Fault (Figure 2-1).  East  of the serpentine b e l t , s l a t y a r g i l l i t e of the Ladner Group i s the most common host f o r gold v e i n s , but serpentine and greenstones of the Hozameen Group, which l i e s west of the serpentine b e l t , are also m i n e r a l i z e d . A l l three rock types and quartz veins are i n t i m a t e l y associated along the b e l t . M i n e r a l i z a t i o n i n quartz veins c o n s i s t s of n a t i v e gold, auriferous arsenopyrite, p y r i t e , uncommon p y r r h o t i t e , and rare c h a l c o p y r i t e .  Gangue  minerals other than quartz and rare c a l c i t e are not reported (with the exception of HSW-35).  Wall rock fragments commonly make up a good p o r t i o n  of the v e i n as at the Emancipation property (HSW-34) where the content of massive, milky quartz decreases away from the v e i n through a wide (about two meter) zone of brecciated s l a t e i n a groundmass of quartz. Quartz veins are not required to l o c a l i z e m i n e r a l i z a t i o n ; a few prope r t i e s (HNW-3,27; HSW-60) report schistose (shear) zones of serpentine with s u l f i d e s and t h i n plates of native gold along f o l i a t i o n s .  Auriferous zones  of t a l c also occur. The p r e v a i l i n g hypothesis on the o r i g i n of s u l f i d e s has been that s e r p e n t i n i z a t i o n of p e r i d o t i t e along the b e l t r e s u l t e d i n formation of veins and auriferous zones by providing easy access to deep-seated magmatic solutions (Cairnes, 1929).  In recent years, geologists working i n the area  TABLE 3-10. Mac No. Name. HNW- 3 Au rum  Type o f Deposit vein  Host Rock Formation  Ladner Croup  HNW-5 Emigrant  Ladner Croup  HNW-6 Snowstorm  Ladner Group Hozameen Group  HNW-7 Idaho  vein  Ladner Group  HNW-8 Montana  vein  Hozameen Croup  HNW-11* Pipestem  arglllltes greenstone serpentine  slate a n d e s i t i c greenstone  Ladner Group  Au py,po,ap (cp)  veins wall rock  N55W.80NE  veins w a l l rock  N80W.45NE  1 , 1  f  P°.ap,Au (py)  q* rock frags  vein  slliclfled.acld  vein  Ladner Group  slate  HNW-U . Star  vein  Ladner Group  slate  Ladner Group  slate  HNW-25 Cem  veins wall rock  slate  HNW-13 Home X  HNW-27 Brett  sill  serpentine  HNW-35 Cold Cord  P tap,Au v  q  vein wall rock stockwork vein and wall rock stringers shear/vein veins  r  N80W, + E-W  r  q* ° c k fraga  qz.cb rock frags  «P.Au  PX.ap . P . P. v  fl  Au  qz  NW.50SW N70V, +  shear  veins disseminated  Ladner Croup  s l a t e at contact with serpentine  HNW-37 Majestic  vein  Ladner Group  HNW-^6 Hlllsbar  vein  Hozameen Group (?)  vein  Ladner Group Hozameen Group  Ladner Croup  HSW-35 Morning  velnlets  slate  veins  slate greenstone f e l d e p i t h i c dikes slate greenstone near quartz d l o r l t e / serpentine contact  HSW-60 P a c i f i c Mines  d l o r l t e dike/serpentine contact ("white rock") shear  Hozameen Group  Ladner Group  stringers  p o r p h y r i t i c dike ln slate  HSW-44 St. P a t r i c k  HSW-116 Camp  q*  veins; s i l l f l e d zones talcose shears  a n d e s i t i c greenstone  slate  HSW-95 Montana  Mineralization  qz rock frags  Ladner Group  HSW-34 Emancipation  Gangue  N50W.25SW  vein  HNW-36 Cold Coin  Mineralized Structure  Au  HNW-9 Rush-of-the Bull F r . HNW-10 Cera  Host Rock Type  Ladner Croup Hozameen Group  HNW-1* Roddick  CHARACTERISTICS OF DEPOSITS IN THE LADNER COLD BELT  greenstone  slate  veins  vein  Au.py  Au N16W.50SW  qz.ca rock frags  py,ap,Au (cp po)  qz.ca (gy)  ap.py (ga)  (  Au,Ag,Zn values  shears  q«  78 have come to b e l i e v e that major mineralized veins and shear zones are r e m o b i l i z a t i o n s of low grade (about 0.10  ounces/ton g o l d ) , disseminated,  p o s s i b l y syngenetic m i n e r a l i z a t i o n i n the Ladner Group ( c f . K a y i r a , 1975). According to Montgomery, et^ al., 1977, p y r i t e , arsenopyrite, p y r r h o t i t e , minor amounts of c h a l c o p y r i t e and n a t i v e gold occur i n a l b i t i z e d quartzchlorite-carbonate s c h i s t which represents a coarse greywacke member of the dominantly a r g i l l a c e o u s Ladner Group.  Small quartz-carbonate-feldspar  v e i n l e t s associated w i t h m i n e r a l i z a t i o n cross-cut a l l formations i n c l u d i n g the Ladner and Hozameen Groups, and contained serpentine bodies personal communication, 1977).  (Sinclair,  Mode of o r i g i n i s not c l e a r , but i f a syn-  genetic model i s accepted, the age of m i n e r a l i z a t i o n before r e m o b i l i z a t i o n i n t o quartz veins would be Lower to Middle J u r a s s i c .  Remobilization i n t o  veins and shears would have occurred during emplacement of the serpentine during major movement along the Hozameen F a u l t i n e a r l y Late  Cretaceous,  p r i o r to 84 Ma. 23-Mile Camp (Table  3-11)  The 23-Mile Camp i s characterized best by i t s d i v e r s i t y i n types of mineral occurrences.  Most deposits occur i n Hozameen Group limestone,  greenstone or dikes, but one i s i n Ladner Group s l a t e and two are i n small plutons which intrude the Ladner Group.  Hozameen-hosted deposits include  four skarns (HSW-3,12,41,117), one disseminated occurrence andesite), and two v e i n deposits (HSW-25,117). include one copper-nickel occurrence  (HSW-42; i n  Ladner-hosted  deposits  (HSW-1), two v e i n deposits i n quartz  d i o r i t e (HSW-2,27), and a b r e c c i a pipe made up of fragments of disrupted a r g i l l i t e (HSW-1).  This b r e c c i a pipe, Canam, i s the f o u r t h l a r g e s t deposit  i n the study area, with reserves estimated at eight m i l l i o n tons grading 0.61 percent copper; i t i s the only deposit to report uranium i n the study area.  TABLE 3-11. Xac No. Name  Type o f Deposit  HSW-1* Canam  porphyry  Host Rock Formation  Ladner Group  \  HSW-2* Invermay  vein  Invermay Stock  CHARACTERISTICS OF DEPOSITS IN THE 23-MILE CAMP Mineralized Structure  Host Rock Type s i l i c e o u s and a r g i l l a c e o u s sedimentary rocks  Width  Attitude  periphery o f b r e c c i a pipe  hornblendite  lenses  a l t e r e d quartz d i o r i t e  lenses i n shear zone  "banded r o c k "  dark bands  qz.ca.cl,to,ep,am,fd qz,ca,ak  1''-6"  variable  HSW-3 Mammoth  skarn  Hozameen Group  HSW-12 D + J  skara  Hozameen Group  c h e r t , v o l c a n i c rocks and some limestone  fractures  HSW-25* S i l v e r Daisy  vein  Hozameen Group  "cherty member"  lenses i n shear zone  2"-8"  N65E-N20E  HSV-27 July  vein  Invermay Stock  quartz d i o r i t e  lenses i n shear zone  3''-4'  NE, + E  limestone and diabase d i k e  contact  a n d e s i t e and granular q u a r t z i t e  jointsj  hornblende  vein  HSW-41 Defiance  skarn  HSW-42* disseminated B.B., Rainbow HSW-117 S t a r #1  vein  Hozameen Group  lime/silicate belt i n . cherty sedimentary rocks and massive- greenstones  andesite  limes tone/greens tone HSW-118 Forks  magmatic  p e r i d o t i t e (?)  HSW-125 Mammoth  magmatic  pyroxenite  Gangue  50'  20'  NW, + S  py,,cp,po (mg.mo.sl, ga,ap,sh,ur) cp,,po ( s i )  qz  ,sl,ap,cp (py.jm)  to (qz)  py,.cp  qz,ca,sd  po,,sh,sl,pr,mo,st  gt,qz,ep,hb,wo,ac  qz, gouge  qz, gouge, rock frags  12' -30'  po,,cp  (sl,ap,ga,Cu)  po,,sl,cp,ga,ap ( t t )  s i , ,ap,cp  po  fractures 6''-r  Mineralization  po, cp.ap.py.ga (jm)  NE.90  N80E.80SE  contact  qz  ap, ga ga (cp.po.sl)  po  dikes  l e s s than 10'  po, s l . c p  80 In contrast to the d i v e r s i t y of deposit types, a major s i m i l a r i t y i n deposits of t h i s camp i s mineralogy.  Chalcopyrite i s present i n ten of  fourteen cases, s p h a l e r i t e and p y r r h o t i t e i n nine, galena and arsenopyrite i n seven. M i n e r a l i z a t i o n i n the Ladner Group probably can be a t t r i b u t e d to i n t r u s i o n of the Invermay Stock.  A smaller pluton two miles northwest of  the Invermay Stock has been dated at 84 + 6 Ma.  Since these two bodies are  l i t h o l o g i c a l l y s i m i l a r , they are considered to be contemporaneous. i n the Hozameen Group cannot be dated as e a s i l y .  Deposits  An important point i s that  the Ladner-Hozameen contact i s the Hozameen F a u l t , which i s cross-cut by the 84 Ma pluton discussed above.  I f most deposits i n t h i s camp are r e l a t e d to  the stocks as products of the same m i n e r a l i z i n g event (due to m i n e r a l o g i c a l s i m i l a r i t i e s and p r o x i m i t y ) , a p o s t - f a u l t i n g age of 84 Ma or younger i s required.  The 84 Ma age i s adopted i n t h i s study.  Ultramafic rocks and r e l a t e d m i n e r a l i z a t i o n most l i k e l y are r e l a t e d to pre-84 Ma t h r u s t i n g along the Hozameen F a u l t , and therefore c o n s t i t u t e an early episode of m i n e r a l i z a t i o n . 10-Mile Creek Camp (Table 8  3-12)  S u l f i d e s i n the 10-Mile Creek Camp occur i n lenses, v e i n s , f r a c t u r e s and as disseminations.  P y r i t e , p y r r h o t i t e , c h a l c o p y r i t e , s p h a l e r i t e and  arsenopyrite occur commonly w i t h quartz, but c a l c i t e has been reported; magnetite, s t i b n i t e and galena are r a r e .  One showing (HSW-82) i s i n  quartz d i o r i t e , two minor ones (HSW-28,55) are i n p o r p h y r i t i c d i o r i t e d i k e s , and the other seven occurrences are contained i n Hozameen Group 9 greenstones or limestone ( ? ) . Q  The large number of occurrences recognized i n t h i s camp r e s u l t e d from i n tense e x p l o r a t i o n during a promotional swindle i n 1910; by 1911 i n t e r e s t i n the area had declined considerably. No production occurred i n t h i s camp. ^Rocks and a l t e r a t i o n associated with m i n e r a l i z a t i o n have not been studied i n d e t a i l ; d e s c r i p t i o n s l i k e " s o f t , white, decomposed rock" are common.  TABLE 3-12. Mac No. Name HSW-9 Billlcan Group HSW-14 Gold Coin  HSW-28 Sunrise  Type o f Deposit  disseminated  massive  Host Rock Formation  Hozameen Group  CHARACTERISTICS OF DEPOSITS IN THE 10-MILE CREEK CAMP  Host Rock Type  sedimentary andesite  rocks and  disseminated  HSW-58 Utah  disseminated  ESW-82 North S t a r  disseminated  Hozameen Group  Hozameen Group  Hozameen Group  limestone (?)  HSW-121 occurrence HSW-122 occurrence  HSW-123 occurrence  massive  Hozameen Group  vein  Hozameen Group  vein  Hozameen Group  massive  Gangue  qz  qz,ca  Hozameen Group  qz  dike  argillite  lens  porphyritic  diorite  dike  f e r r u g i n o u s limestone  diorite  qz  qz,ca  6"-l'  disseminations  andesitic  i n j e c t e d (?) l e n s  greenstone  lens  greenstone  f i s s u r e d zone  limestone (??)  andesite  py.sl.ga  py,cp,po,ap  qz  py.cp ap,ga,sl,po  sp po,py,cp gt.ep  4'-6'  veins  2"-10"  vein  l'-2.5'  lens  py.sl  py.cp  greenstone c l o s e to intrusive  greenstone  py,sl,po,cp,sb,ap,ga,jm  py.sl  s t r i n g e r s and disseminations veins  Mineralization  si  lenses, stringers and d i s s e m i n a t i o n s  quartzite,  quartz Hozameen Group  HSW-109 S k a g i t Giant  veins, stringers and lenses i n fractures  Attitude  f r a c t u r e s near quartz d i o r i t e  diorite HSW-5 5 Steamboat Mtn.  Width  lenses  Hozameen Group  disseminated  disseminated  Mineralized Structure  qz ' (qz) • (qz) qz (at,sn)  Fy.mg  py,cp,po,sb sl.ap py.po.ap mg  00  82 S k a r n i f i c a t i o n i s commonly reported, but only one deposit (HSW-109) reports a skarn assemblage.  P o s i t i v e i d e n t i f i c a t i o n of limestone i s r a r e ,  therefore, i t i s u n l i k e l y that t h i s mode of o r i g i n can s a t i s f a c t o r i l y describe the e n t i r e d i s t r i c t . Dikes and other i n t r u s i v e rocks i n the area have been looked upon as m i n e r a l i z i n g sources because they commonly contain disseminated  sulfides.  However, dikes may have picked up s u l f i d e s from p r e - e x i s t i n g accumulations during i n t r u s i o n .  The undefined nature of massive and disseminated min-  e r a l i z a t i o n i n t h i s camp suggests that s u l f i d e deposits, l i k e t h e i r host rocks, have undergone deformation.  The p r e c i s e character of s u l f i d e bodies  p r i o r to deformation i s not known. The a s s o c i a t i o n of copper-zinc m i n e r a l i z a t i o n i n greenstones might lead to speculation that massive, disseminated and v e i n deposits are r e l a t e d t o syngenetic v o l c a n i c accumulations, but much more data are necessary.  Age of m i n e r a l i z a t i o n i s e i t h e r Paleozoic ( i f syngenetic) or  mid-Cretaceous ( i f epigenetic or remobilized during  deformation).  Harrison Lake D i s t r i c t (Table 3-13) The Harrison Lake Formation contains abundant disseminated mineralization.  copper-zinc  Chalcopyrite, s p h a l e r i t e , p y r i t e and rare galena and  p y r r h o t i t e occur as v e i n l e t s associated w i t h f r a c t u r e s i n c a l c - a l k a l i n e , l o c a l l y p y r i t i c , p y r o c l a s t i c v o l c a n i c rocks. f i c a t i o n i s common. reports b a r i t e .  Quartz gangue and/or s i l i c i -  One report describes c a l c i t e gangue, and another  Some reports do not describe gangue minerals.  Early d e s c r i p t i o n s of the Seneca volcanogenic deposit (HSW-13) are much l i k e those of other deposits i n the Harrison Lake Formation.  Although  work began on Seneca i n 1898, i t was not u n t i l 1971 that Geology, E x p l o r a t i o n and Mining i n B r i t i s h Columbia reported a s t r a t i f o r m lens of massive  TABLE 3-13. Mac No. Name  Type o f Deposit  Host Rock Formation  CHARACTERISTICS OF DEPOSITS IN THE HARRISON LAKE DISTRICT  Host Rock Type  G-145 Rat  disseminated  H a r r i s o n Lake Formation  volcanic  G-154 Cleveland  disseminated  H a r r i s o n Lake Formation  brecciated, s i l i c i f i e d rhyolite tuff  HSW-13 Seneca  volcanogenic  H a r r i s o n Lake Formation  rhyolite l a p i l l i tuff and b r e c c i a  HSW-15* V a l l e y View  disseminated  Agassiz P r a i r i e Formation  greywacke metavolcanic  rocks  H a r r i s o n Lake Formation  HSW-103 IAM  disseminated  H a r r i s o n Lake Formation  HSW-106 Fab  disseminated  H a r r i s o n Lake Formation  HSW-112 Ascot  disseminated  H a r r i s o n Lake Formation  HSW-113 Sku  porphyry  H a r r i s o n Lake Formation  HSW-114 SF  vein  H a r r i s o n Lake Formation  pyritized, sericitized a n d e s i t e flows  HSW-115 Top  vein  H a r r i s o n Lake Formation  s i l i c i f i e d , epidotized, pyritized pyroclastics  HSW-120 KU  disseminated  H a r r i s o n Lake Formation Echo I s l a n d Formation  f e l s i c v o l c a n i c rocks  H a r r i s o n Lake Formation  Gangue  a n d e s i t e flows and agglomerate • r h y o l i t e '.  Mineralization (Cu and Zn t r a c e s )  veinlets  fractures  disseminated  disseminated  Attitude  gossan  HSW-96 Luv  HSW-126 J No.6  Mineralized Structure  qz  cp,sl,py,po,Bi,mg,cc  qz,ca,ba  py,cp,sl,cv,tt,ga,mr  (qz)  gossan  py.cp (1966 i n f o ) cp.bo.cc (1974 i n f o )  fractures  cp.sl.py  stringers i n breccia pipe  ba  sl.cp.ga  s i l i c i f i e d , pyritized, f r a c t u r e d agglomerate  stringers  qz  py.cp.sl.cc  a n d e s i t e flows and breccia  fractures  qz  py.cp.sl  a l t e r a t i o n halo around g r a n i t e pluton  sedimentary,  py  qz  blebs and v e i n l e t s i n shear  qz,ca  cp.sl.py  ga,cp,po  sl.cp  (py.po)  tuffaceous  p o r p h y r i t i c andesite and flow b r e c c i a  shear which p a r a l l e l s 10' wide p y r i t i z e d t u f f band  N70W.65SW  - cp  CO  84 s u l f i d e s interpreted as syngenetic m i n e r a l i z a t i o n .  On t h i s b a s i s , other  v e i n or disseminated showings w i t h s t r u c t u r e and mineralogy s i m i l a r to that of Seneca might be r e - i n t e r p r e t e d as small volcanogenic manifestations. In t h i s i n t e r p r e t a t i o n , age of m i n e r a l i z a t i o n i n the d i s t r i c t would correspond to the mid-Jurassic age of the Harrison Lake Formation.  Of course,  concentration of s u l f i d e s by l a t e r hydrothermal f l u i d s flowing through the s u l f i d e - r i c h v o l c a n i c rocks a l s o would be a p o s s i b i l i t y , but i n i t i a l mine r a l i z a t i o n would be syngenetic, and there seems to be no evidence that implies a superimposed  r e m o b i l i z i n g event.  Some v e i n stages of the volcano-  genic system can continue beyond the period of host rock d e p o s i t i o n ; these would be s l i g h t l y younger than host rocks. F i r e Lake Camp (Table 3-14) The F i r e Lake Group i s dominantly sedimentary i n o r i g i n , but includes greenstones which contain f i v e of the s i x deposits reported i n the formation. Deposits i n greenstone are quartz veins w i t h c h a l c o p y r i t e and, commonly, native gold.  Veins are not continuous but consist of lenses and gash veins  i n a wider (possibly sheared) zone.  The s i x t h deposit i s contained i n a  b e l t of b r e c c i a t e d sedimentary rocks which enclose l e a d - z i n c m i n e r a l i z a t i o n i n quartz and c a l c i t e gangue. An o r i g i n by hydrothermal a c t i o n along zones of weakness during i n t r u s i o n of surrounding plutons i s most l i k e l y .  Age of m i n e r a l i z a t i o n i s  therefore Late Cretaceous. P i t t Lake (Table 3-15) Most deposits i n the P i t t Lake area are quartz veins i n i n t r u s i v e rocks of the Coast P l u t o n i c Complex; s i m i l a r m i n e r a l i z a t i o n i s scattered throughout the Coast P l u t o n i c B e l t .  The veins a t P i t t Lake carry p y r i t e , chalco-  p y r i t e , uncommon galena and p y r r h o t i t e , and rare s p h a l e r i t e and c o v e l l i t e .  TABLE 3-14. Mac No. Nane  Type o f Deposit  G-26 Money Spinner  vein  G-27 Barkoola  vein  G-29  Host Rock Type  Mineralized Structure  vein  Width  Attitude  In  r a l l e lzone veins p o r p h y r i t i c greenstone p ashear and lenses greenstone i n 25' wide zone  F i r e Lake Group  F i r e Lake Group  G-28 Blue Lead  Host Rock Formation  CHARACTERISTICS OF DEPOSITS IN THE FIRE LAKE CAMP  4 parallel lenses  Gangue  Mineralization  qz  Py,cp,Au,bo  qz  cp.Au  up to 18" N85E.45NE  qz  cp.Au  qz  cp  3'-A' up t o 2*  vein  F i r e Lake Group (?)  vein  F i r e Lake Group  greenstone  gash v e i n s  up to 36"  vein  F i r e Lake Group  greenstone  gash v e i n  0-14"  F i r e Lake Group  b r e c c i a t e d sedimentary rocks  N10W.60SW  King No.l G-30 Richfield G-36* Dandy  vein  E-W.26N  qz  vein breccia belt  py 100'-200'  qz,ca cement  (ga.sl)  g a . s l (py)  CO Ln  TABLE 3-15. Mac No. Name  Type o f D e p o s i t  Host Rock Formation  CHARACTERISTICS OF DEPOSITS IN THE PITT LAKE AREA  Host Rock Type  Mineralized Structure  Width  Attitude  Gangue  Mineralization  G-l Jubilee G-7  vein  G-82 S t . John  diorite  vein  l'-1.5'  N55W.90  vein  Coast P l u t o n i c Complex  quartz d i o r i t e  fractures  2"-l' 2"-4"  N25E.80NW N25E.80NW  vein  Coast P l u t o n i c Complex  granodiorite  shear zone  vein  vein  TABLE 3-16. Mac No. Name G-23 * Cambrian Chieftan G-24* King Midas  G-84 Sundown G-93 War  qz  vein  S t . Paul G-20 Standard G-34* Viking  stringer(s) Coast P l u t o n i c Complex  Type o f D e p o s i t  Host Rock Formation  N90E.80S  2"-4"  NW.90  py.cp qz qz, ko (ca) rock f r a g s  qz  Host Rock Type  Gambler Group  limestone  skarn  Coast P l u t o n i c Complex Gambier Group  granite/granodiorite  Mineralized Structure  Width  f r a c t u r e s i n skarn  calcareous remnant  irregular, altered, s i l i c i f i e d contact zone  Attitude  Gangue  g t , ep  ep,gt,ca,mg  porphyry  porphyry  py.ga.cp  py,po,cp ( c v . s l )  py.cp  CHARACTERISTICS OF DEPOSITS ON THE SECHELT PENINSULA  skarn  Gambier Group Coast P l u t o n i c Complex  py.cp  Mineralization  cp,py,mg,sl  cp,py,Cu,sc.  Cu.Mo  v o l c a n i c r o c k s , skarn, and h o r n f e l s  stockworks  granite  shears  cp,mo  v e i n - l i k e bodies along contact  cp.py.mg.sl  shear  ng,py.cp  G-94 Day  skarn  Gambler Group  c h e r t , limestone (near i n t r u s i o n s )  G-138 M.C.  skarn  Gambier Group  limestone,  dolostone  qz  cp (mo)  (ml,cc,cv)  87 Veins are r e l a t i v e l y narrow (two inches to one and one h a l f feet) and are steep to v e r t i c a l ; no preferred o r i e n t a t i o n i s apparent. The o r i g i n of veins i n p l u t o n i c rocks i s a t t r i b u t e d to l a t e stage hydrothermal a c t i v i t y of host plutons i n Late Cretaceous  time.  Sechelt Peninsula (Table 3-16) Although skarns are uncommon i n the Coast P l u t o n i c B e l t , four skarn deposits occur on the Sechelt Peninsula.  Deposits were formed i n limestone  of the Gambier (?) Group during i n t r u s i o n of surrounding plutons of the Coast P l u t o n i c Complex.  C h a r a c t e r i s t i c skarn assemblages c o n s i s t of garnet,  epidote, magnetite, p y r i t e and c h a l c o p y r i t e ; some s p h a l e r i t e , n a t i v e copper and s p e c u l a r i t e have also been reported.  Age of m i n e r a l i z a t i o n  corresponds  to plutonism i n mid-Cretaceous time. In a d d i t i o n to skarn m i n e r a l i z a t i o n , two porphyry occurrences appear i n t h i s area.  They are t y p i c a l of most porphyry deposits of the Coast  P l u t o n i c B e l t , c o n s i s t i n g of disseminated copper and molybdenum s u l f i d e s i n p l u t o n i c (and r a r e l y pendant) rocks.  The age of porphyry m i n e r a l i z a t i o n  probably i s equivalent to that of the p l u t o n i c rocks and skarns.  ISOLATED PAST PRODUCERS AND IMPORTANT PROSPECTS Table 3-17 presents information on deposits w i t h production records that were not discussed previously because of t h e i r i s o l a t e d l o c a t i o n s outside designated camps and d i s t r i c t s .  The Z e l and Gem deposits are  included and discussed i n d i v i d u a l l y because they are the most accurately dated deposits i n t h i s s e c t i o n . Zel A small muscovite g r a n i t e pluton intrudes b i o t i t e g r a n o d i o r i t e of the Coast P l u t o n i c Complex 20 kilometers east of Squamish on the Z e l property  TABLE 3-17 . Mac No. Name  Type o f D e p o s i t  G-5 Zel  porphyry  Host Rock Formation 83.4 Ma p l u t o n  CHARACTERISTICS OF ISOLATED PRODUCERS AND IMPORTANT OCCURRENCES.  Host Rock Type muscovite g r a n i t e (some pegmatite)  G-14 Lorraine  shear  G-25 Ashloo  vein  HSW-8 Empress  skarn  C h i l l i w a c k Group  HSW-11 Eureka-Victoria  vein  Chuckanut Formation  conglomerate  HSK-33' Anna  skarn  C h i l l i w a c k Group  limestone  HSW-36 Aufeus  vein  HNW-1 Gem  HNW-2 Providence  porphyry  vein  Bowen I s l a n d Group  Width  veins and up to 2.5 disseminations two shears  b a s i c dike (?) intrudes granodiorite  Attitude 1  quartz d i o r i t e  34.2 Ma intrusion  q u a r t z monzonite porphyry  Gangue qz  N35W.80N  bands, l e n s e s and s t r i n g e r s i n shear  gt,ca,fd,ep  f r a c t u r e zone  shear . with v e i n s "  disseminations and v e i n s i n and around breccia pipe  1-12" 2"-2*  N85E.50S N77E.40S N77E.23S N82E.43S  Mineralization bo cp,cv mo f  f  py,cp,po,ml,az  qz  limestone  Spuzzum p l u t o n  H a r r i s o n Lake Formation  Mineralized Structure  py.cp.po  cp ,bo ,mg ,py, mo ,wo, az.ml  sd,qz  py,tt,mr,ml,az  ep.gt  cp,ml,az,cc  qz,ca ap.py.cp  qz mo ( p y , p o , c p , s h , s l , B i )  vein py.Au  co co  89 (G-5).  Chalcopyrite, b o r n i t e , c o v e l l i t e and molybdenite occur as dissem-  i n a t i o n s , i n quartz veins and i n pegmatites r e l a t e d to the granite plug. A K/Ar date of 83.4 + 4.2 Ma was obtained from g r a n i t e , and i s used to approximate the age of m i n e r a l i z a t i o n (G. J . Woodsworth, personal communic a t i o n , 1978). Gem Porphyry m i n e r a l i z a t i o n of the Gem deposit (HNW-1) i s r e l a t e d genet i c a l l y to a quartz monzonite porphyry b r e c c i a pipe.  The pipe i s associated  w i t h a small g r a n i t i c plug which intrudes S e t t l e r Schist and Custer Gneiss. Molybdenite occurs as disseminations i n host rocks, i n quartz veins and i n massive molybdenite veins.  Veins are randomly oriented i n a l l rock types,  but are h i g h l y concentrated around the contact between the pipe and the granite i n t o which the pipe intrudes. P y r i t e , p y r r h o t i t e , c h a l c o p y r i t e , s c h e e l i t e , s p h a l e r i t e and bismuthinite occur l o c a l l y i n quartz v e i n s , and gold values up to 0.02 ounces/ton were reported i n 1938. Age of m i n e r a l i z a t i o n corresponds to i n t r u s i o n of the quartz monzonite porphyry b r e c c i a pipe.  A K/Ar date on b i o t i t e from the quartz monzonite  i n d i c a t e s i n t r u s i o n occurred at l e a s t 34.2 + 1.2 Ma (R. L. Armstrong, personal communication, 1978). Other Deposits The remaining deposits are skarns, veins and one shear.  The formation  of skarn deposits can be a t t r i b u t e d with r e l a t i v e c e r t a i n t y to i n t r u s i o n of plutons, but the age of veins and shears can only be estimated.  Veins i n  p l u t o n i c and non-plutonic rocks are probably r e s u l t s of i n t r u s i o n of host or nearby plutons, but m i n e r a l i z a t i o n could have occurred at any time a f t e r formation of the host rock. G-14  Lorraine  Estimations of deposit ages are as f o l l o w s : Cretaceous ?  90 G-25 HSW-8 HSW-11 HSW-33 HSW-36 HNW-2  Ashloo Empress Eureka-Victoria Anna Aufeus Providence  Upper Cretaceous ? l a t e Oligocene or Miocene Miocene (21 Ma) l a t e Oligocene or Miocene Upper Cretaceous (83 Ma) Upper Cretaceous ?  Absolute ages assigned to HSW-11 and 36 are based on K/Ar dates on p l u t o n i c rocks l e s s than one kilometer from the deposits.  SUMMARY The metallogenic h i s t o r y of the study area as discussed i n t h i s chapter i s presented i n Figure 3-4 and Table 3-18.  Figure 3-4 i s a d u p l i c a t e of the  time-space p l o t of Figure 2-2 onto which m i n e r a l i z a t i o n of d i s t r i c t s , camps and i n d i v i d u a l producers has been superimposed.  An explanation of the  symbols used i n t h i s f i g u r e i s contained i n Figure 3-4a.  In the case of the  B r i t a n n i a and Harrison Lake D i s t r i c t s , volcanogenic m i n e r a l i z a t i o n represents a l l occurrences except porphyries.  Where more than one p o s s i b i l i t y e x i s t s  as t o the o r i g i n of a deposit, a l l p o s s i b i l i t i e s are i n d i c a t e d and accompanied by question marks.  I f a dashed-line symbol i s not present f o r  epigenetic occurrences, m i n e r a l i z a t i o n i s assumed to be about the same age as i t s host (e.g., veins i n the Coast P l u t o n i c Complex). Table 3-18 describes the d i s t r i b u t i o n of metal deposits through time w i t h respect to a c t u a l and/or p o t e n t i a l causative events.  Figure 3-4a.  Explanation of Symbols on Figure 3-4.  Vein i n d i v i d u a l deposit Skarn  Q group of deposits  Disseminated fj'W major mine Shear In the case of epigenetic mineralization:  Magmatic Volcanogenic Porphyry  ^ — ^ ^  time of formation  ^ </  Massive  l o c a t i o n i n host ro unit  Q  1.  Britannia D i s t r i c t  12.  P i t t Lake  2.  Northair D i s t r i c t  13.  Sechelt Peninsula  3.  Giant Mascot D i s t r i c t  14. Z e l  4. Eagle Belt  15.  Gem  5.  Summit Camp  16.  Lorraine  6.  Jim K e l l y Creek Camp  17.  Ashloo  7.  Ladner Gold Belt  18.  Empress  8.  23-Mile Camp  19. E u r e k a - V i c t o r i a  9.  10-Mile Creek Camp  20.  Anna  10.  Harrison Lake D i s t r i c t  21.  Aufeus  11.  F i r e Lake  22.  Providence  TABLE 3-18.  TIME SPAN I. II.  IV. V.  VI. VII.  VIII.  IX.  X.  EVENTS  DISTRICTS, CAMPS AND DEPOSITS INVOLVED  Pre-Devonian Upper Paleozoic/ Lower and Middle T r i a s s i c  III.  SUMMARY OF METALLOGENIC HISTORY  deposition of volcanogenic s u l f i d e s i n the Hozameen Group ?  10-Mile Creek Camp ?  deposition of syngenetic gold i n the Ladner Group ?  Ladner Gold ?  deposition of volcanogenic s u l f i d e s i n the Harrison Lake Formation  H a r r i s o n Lake  porphyry and v e i n m i n e r a l i z a t i o n during l a t e stages of formation of the Eagle Complex  Eagle Belt  magmatic s u l f i d e formation In Giant Mascot Ultramafite  Giant Mascot D i s t r i c t  deposition of volcanogenic s u l f i d e s i n the Gambier Group  Britannia D i s t r i c t  deposition of volcanogenic s u l f i d e s i n the northern Gambier (?) Group ?  Northair D i s t r i c t  Peraian/Triassic Upper T r i a s s i c Lower and Middle J u r a s s i c  District  Upper J u r a s s i c Lower Cretaceous  mid-Cretaceous ( l i m i t s undefined)  Upper Cretaceous  Tertiary  ?  vein formation near the Hozameen Fault and i n t r o d u c t i o n of disseminated gold (?) Into the Ladner Group during movement of the Hozameen Fault  Ladner Gold Belt  formation of epigenetic disseminated, massive and vein deposits i n the Hozameen Group during deformation ?  10-Mile Creek Camp ?  skarn, v e i n and porphyry m i n e r a l i z a t i o n i n the Coast P l u t o n i c Complex and Spuzzum pluton during l a t e stages of plutonism  Sechelt Peninsula, L o r r a i n e , Northair D i s t r i c t , P i t t Lake, Ashloo, F i r e Lake, Providence, Aufeus, Z e l  skarn, v e i n , porphyry and disseminated m i n e r a l i z a t i o n i n the Hozameen Group r e l a t e d to i n t r u s i o n of small pluton(s) ?  23-Mile Camp ?  porphyry m i n e r a l i z a t i o n associated with minor l a t e plutonism i n the Spuzzum P l u t o n i c Belt  Gem  skarn and v e i n formation during i n t r u s i o n i n the Cascade Belt  Anna, Empress, EurekaVictoria  vein m i n e r a l i z a t i o n i n f r a c t u r e zones I n the Ladner Trough and Eagle P l u t o n i c B e l t possibly r e l a t e d to extrusion of the Coquihalla Group ?  Summit Camp, Jim K e l l y Creek Camp  93 4.  COMPUTER STUDY  INTRODUCTION This chapter deals with the s t a t i s t i c a l aspects of mineral occurrences. The main concern i s to catalogue and analyse a v a i l a b l e information on s i t e s at which metals have been concentrated and to draw conclusions r e l a t i v e to the genesis of these concentrations. In theory, the value of a computerized mineral deposits f i l e such as MINDEP i s that i t enables f a s t r e t r i e v a l and r e o r g a n i z a t i o n of l a r g e amounts of data which would be tedious to deal with manually 1971).  ( c f . Orr and S i n c l a i r ,  I f the data bank i s set up properly and programs are a v a i l a b l e f o r  s e l e c t i v e information r e t r i e v a l and o r g a n i z a t i o n , the time spent by the r e gional geologist or metallogenesist a c q u i r i n g data i s minimal.  A f t e r geol-  o g i c a l and r e l a t e d features of each deposit are entered i n t o the system, deposits may be grouped e a s i l y on the b a s i s of a wide v a r i e t y of parameters. Evaluation of such data might lead to rapid a p p r a i s a l of c h a r a c t e r i s t i c s and controls of m i n e r a l i z a t i o n . The v a r i a b l e s examined below are commodities ( s p e c i f i c a l l y metals), deposit type, t e c t o n i c s e t t i n g , host rock formation and host rock type. Data are presented on histograms; numerical values are tabulated i n c o n t i n gency tables i n Appendix A.  S p a t i a l d i s t r i b u t i o n and zonation of metals and  deposit types are presented on maps produced d i r e c t l y from the computer on a Calcomp p l o t t e r . Commodities are reported i n the l i t e r a t u r e e i t h e r as assays or by the presence of s u l f i d e s of the metal concerned.'''  I n some cases, mining claims  were staked on the assumption that c e r t a i n metals were present, although . ^"An exception i s i r o n , which occurs i n nearly a l l deposits as p y r i t e (and r a r e l y as s i d e r i t e and p y r r h o t i t e ) , but i s usually not reported unless there are concentrations of magnetite.  94 subsequent work has not v e r i f i e d these assumptions.  Many such instances  were noted i n the l i t e r a t u r e , and the unrecognized commodities were deleted from the data f i l e ; some errors i n t h i s regard might s t i l l be present. Inaccurate and/or incomplete sources of information prevented systema t i c evaluation of the r e l a t i v e importance of metals between and w i t h i n deposits.  Wherever p o s s i b l e , metals are l i s t e d i n order of abundance or  economic importance, but s t a t i s t i c a l counts of metal occurrences consider each metal i n a deposit w i t h equal emphasis.  I t i s believed that the  presence of a metal i s the primary concern, regardless of amount or concent r a t i o n , but where information i s a v a i l a b l e , metals w i t h only trace assay values were deleted. On the other hand, metals have been included by the w r i t e r where a metal s u l f i d e has been reported to occur (commonly i n unknown amounts), but the contained metal was not included i n the descript i o n of the occurrence by previous reporters.  Deposits w i t h production  records (referred to as "producers") are distinguished on histograms i n order to compare v i a b l e economic occurrences w i t h those that d i d not produce. Five deposits (Table 4-1) whose s i z e s greatly exceed the average deposit s i z e i n the study area are d i s t i n g u i s h e d a l s o . Further d e s c r i p t i o n of deposit types on the basis of metal content i s presented i n Figure 4-1.  These histograms i d e n t i f y metal associations i n  each type of deposit, and can be r e f e r r e d to when c l a r i f i c a t i o n of metal and deposit type r e l a t i o n s h i p s i s required i n the subsequent d i s c u s s i o n . Host rock formation r e f e r s to the u n i t i n which m i n e r a l i z a t i o n occurs, whether i t i s a formation, group, or named pluton; i t i s not s p e c i f i e d f o r some deposits i n small u n i t s of unknown c o r r e l a t i o n , d i k e s , or small plutons of unknown age.  However, host rock type applies to every deposit f o r which  a description i s available. Zoning maps require a method of recognizing deposit s i z e , but since the  TABLE 4-1. Cu Britannia ' G-3 1  Pb  1.1%  2  GRADE AND TONNAGE OF MAJOR DEPOSITS  Zn .65%  Au ,02oz/T  Ag .20oz/T  Giant Mascot ' .33% HSW-4 1  Northair ' J-130 4  Canam HSW-1 Aurum HNW-3  6  2.7%  4.0%  .40oz/T  .61%  7  4.60oz/T  Production  Total Resources  52,783,964 T .77%  3  5  Ni  6,081,133 T  7,577,000 T 330,637 T 8,000,000 T  .098oz/T  3,650,000 T  '''Data calculated from production records. 2 B r i t i s h Columbia Department of Mines and Bureau of Economics and S t a t i s t i c s , V i c t o r i a , B r i t i s h Columbia 3 B r i t i s h Columbia Department of Mines and Bureau of Economics and S t a t i s t i c s , V i c t o r i a , B r i t i s h Columbia, and Christopher and Robinson, 1974 4 Data c a l c u l a t e d from reserves estimate. ^Northair Mines L t d . , Annual Report, 1977 P i l c h e r and McDougall, 1976 ^Montgomery, et a l . , 1977  30-1  Y em  n  rorphurij X=loo% 10J  3<H  2<M  jDisseminafce.d'  x=ioo% 2oJ  Fe C. Ni Cv Zn «< M.fljCd So U ft. Pb B; V  10-j  10-  3-  1 0 -  F* Co N; C» Z n A> rt. A , Cd S h Wfl«th Rt U  f i a s s iv e X=100%  EL F e C o / V ; C»2n A . H o f l j C d S k U flu ft Bi U  n  ri  Fe Co N; Cv2*t\i fl. ftj Cd  n  W A« Pk B i U  2 0 - .  20.  Skear  Skam  X'ioo'/c  10.  10-.  Vol FeCoNiCu2«ftsn.A CJSbW/)gPi.8« U 3  F e C o N i C u Z w / U r M g C d S V ) U ftoPfc ft U  canogemc  F a C N i Cu2»/»«CI./» CdSl. W f l . 9  K U  3 1  feC.  Ni CuZn ftsl^flg C i S k U R«Pk 6\ 0  Figure 4-1. Number of occurrences of each deposit type with respect to c h a r a c t e r i s t i c metals. "X" i s the percent of t o t a l occurrences of each deposit type i n the study area f o r which metal content i s known. T r i a n g l e s i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent a l l others (see Table 4-2).  97  dimensions of very few deposits are known, a r a t i n g system of the magnitude of deposits according to the status of e x p l o r a t i o n or production has been defined as a s u b s t i t u t e (see Table 4-2).  Magnitude I , the smallest,  includes both showings and prospects because f o r many the d i s t i n c t i o n between them i s based on whether or not geochemical or geophysical surveys were made.  These remote sensing techniques are employed commonly i n recent  e x p l o r a t i o n programs, whereas older programs r e l i e d p r i n c i p a l l y on s u r f i c i a l mapping.  Magnitude I I i s assigned to developed prospects, because although  they have not produced, they have a t t r a c t e d more a t t e n t i o n than showings and prospects.  Magnitude I I I i s assigned to deposits which produced s e v e r a l  thousand tons or l e s s .  The f i v e major deposits of Table 4-1 are of magni-  tude IV. Each commodity i s examined f i r s t w i t h respect to i t s d i s t r i b u t i o n among deposit types to determine i f metals occur p r e f e r e n t i a l l y i n any p a r t i c u l a r type.  Subsequent studies examine d i s t r i b u t i o n s r e l a t i v e to  tectonic s e t t i n g , host rock formation and host rock type.  A f i n a l section  examines the a r e a l d i s t r i b u t i o n df metals and deposit types f o r r e g i o n a l zoning patterns which might r e l a t e to deposit genesis. METAL AND DEPOSIT TYPE ABUNDANCES Copper i s reported i n 73 percent of a l l deposits (Figure 4-2), but the percentage of deposits which produced copper (10 percent) i s the same as gold and s i l v e r , which are found i n 45 percent of a l l deposits.  Zinc has  been reported i n more cases than i t s common a s s o c i a t e , lead, but the percentage of producers f o r each (5.6 percent) are equal because deposits which produce one commonly produce the other. remaining reported metals.  Molybdenum i s more common than the  Very few deposits reporting molybdenum have  proven economic, but the number of molybdenum producers i s approximately that of i r o n , arsenic and tungsten, which are much l e s s common than molyb-  TABLE 4-2. DEPOSIT STATUS BASED ON HISTORY OF EXPLORATION, DEVELOPMENT OR PRODUCTION  Status  History  Showing  no development or s i g n i f i c a n t e x p l o r a t i o n , or no d e s c r i p t i o n of m i n e r a l i z a t i o n a v a i l a b l e  Prospect  geochemical or geophysical survey, and/or d e t a i l e d mapping, or developed by open cuts or short adits  Developed Prospect  considerable e x p l o r a t i o n and development, w e l l - e s t a b l i s h e d camp f a c i l i t i e s ; r a r e l y some ore has been m i l l tested  Past Producers  production record of several thousand tons or less  Producers  Magnitude  Number of Deposits 152 55  II  20  III  30  production record over several hundred thousand tons  IV  4  c u r r e n t l y producing deposits  IV  1  99  25Z  100-  2Z5  Percent  Deposits  80  •200  7^  -175  60  -150  Numb QX Deposits  125  so-  -100  30-  -75  20-1  -SO  IS  10'  1  Fe 'Co 'Ni ICulZn'Rs'Molftg'Cd'SD'w IfluWBi >U  Figure 4-2.  T o t a l number of occurrences of each metal (metal content i s known f o r 97.9% of a l l deposits i n the study area). Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits w i t h production records; blank bars represent showings, prospects a n d developed prospects.  100 denum.  The d i s t r i b u t i o n of major deposits (Figure 4-2) roughly  general abundances and percentages of producers.  reflects  S i m i l a r l y , the d i s t r i b u t i o n  of producers r e f l e c t s the abundance of metal occurrences.  N i c k e l i s an  exception; the only deposit to produce was a major one. Figure 4-3 portrays the d i s t r i b u t i o n of deposits among the eight types found i n the area.  Veins are by f a r the most common deposit type, and the  most common type to go i n t o production, as nineteen v e i n deposits are producers , whereas no other type includes more than three producers.  Porphyries  and disseminated deposits are about h a l f as abundant as v e i n s ; skarns shears each account f o r ten percent of a l l deposits.  and  I t i s interesting  note that the two recognized volcanogenic deposits are producers,  to  although  the c o r r e l a t i o n i s probably not s i g n i f i c a n t , but more a r e f l e c t i o n of the lack of r e c o g n i t i o n of other deposits as volcanogenic; many disseminated, v e i n and shear deposits might, i n f a c t , be volcanogenic i n o r i g i n .  Major  deposits do not demonstrate close t i e s w i t h any p a r t i c u l a r type of deposit, but are evenly d i s t r i b u t e d among most types.  Magmatic and  volcanogenic  types are r e l a t i v e l y uncommon, but include major deposits. POSSIBLE ORE CONTROLS Deposit Type Figure 4-4a,b i l l u s t r a t e s the d i s t r i b u t i o n of the most common metals among deposit types.  Metals reported i n less than f i v e percent of deposits  are not shown because they lack a s u b s t a n t i a l able information i s not d e f i n i t i v e .  data base and l i m i t e d a v a i l -  Each metal d i s t r i b u t i o n pattern can be  compared to that of Figure 4-3; d i f f e r e n t d i s t r i b u t i o n patterns f o r metals r e l a t i v e to each deposit type suggest that the occurrence of the metal i s controlled  by deposit type.  Generalizations made from these  distributions  regarding metal sources are s p e c u l a t i v e , but are mentioned where appropriate.  101  80  ,-35  70-1  h30  Number QQ-\ oS  1-25  Percent o? Deposits  • 20  -15 30-  -10 Z0-.  -5"  10AI:  C  ^  '  CO  Co  c QJ  in  Figure 4-3.  >  .ST  CO  £ TO  £ CO  o —  cy  o CO  o  T o t a l number of occurrences of each deposit type (deposit type i s known f o r 88.4% of a l l deposits i n the study area). Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent depo s i t s w i t h production records; blank bars represent showings, prospects and developed prospects.  102  Gold 60-1  c  SO-  opper  Sil ver  J  \-HO.  x=q3%  h 3 M  \-20-A  •10-  I o SZ > ^ V Ql  u -P a) ca  CO  3->.<J  c £<  £  lb  tn cn  2- (O  ST!  g  0_  crj  QJ CD  NT" >_  o c d . ca o  CO  a) <2 s: a o -1  CO  c  <0  u  O  Figure 4-4a. Number of occurrences of copper, gold and s i l v e r with respect; to deposit type. "X" i s the percent of t o t a l deposits of each metal f o r which deposit type i s known. Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  103  10.  I ror,  10-  5A E  -  <U  <o  Oj  3  ^  s  S-M o2  {F5S  CP  o  c£ c O  Figure  4-4b.  Number o f o c c u r r e n c e s o f m o l y b d e n u m , z i n c , l e a d , i r o n a n d n i c k e l w i t h respect to deposit type. "X" i s t h e p e r c e n t o f t o t a l d e p o s i t s o f e a c h m e t a l f o r w h i c h d e p o s i t t y p e i s known. T r i a n g l e s i d e n t i f y major d e p o s i t s of Table 4 - 1 ; s t i p p l e s represent deposits with production records; blank bars represent s h o w i n g s , p r o s p e c t s and d e v e l o p e d prospects.  104 The d i s t r i b u t i o n of copper (Figure 4-4a) i s much the same as that of deposit types (Figure 4-3), r e f l e c t i n g the diverse and widespread  occurrence  of the metal. Gold and s i l v e r occur dominantly  i n v e i n s , but whereas gold i s s i n g -  u l a r l y dominant i n v e i n s , s i l v e r i s reported also i n other types of deposits.  The r a t i o of s i l v e r occurrences  to gold occurrences  i n dissem-  inated, shear, skarn and porphyry deposits i s 1.27, 1.30, 1.50 and 2.00, respectively. Molybdenum (Figure 4-4b) i s prominent i n porphyry deposits, suggesting that i n t r u s i v e a c t i v i t y i s responsible f o r the concentration of molybdenum. Further support f o r t h i s hypothesis comes from the f a c t that skarns are the only other type of deposit to report molybdenum w i t h any s i g n i f i c a n t f r e quency ( f i v e of 23 skarns i n the area report molybdenum). The d i s t r i b u t i o n of lead shows a dominance i n veins, and a conspicuous absence i n porphyry and magmatic deposits.  Zinc i s almost as widespread as  copper, generally occurring i n veins or disseminated deposits.  Shears and  skarns also report considerable z i n c . Iron oxides are not reported commonly.  Not enough data are present to  generalize beyond the f a c t that they are reported most often i n skarns. N i c k e l i s reported as uncommonly as i s i r o n , and i s r e s t r i c t e d to magmatic deposits.  Ultramafic rocks are the most l i k e l y source of n i c k e l  since they are n i c k e l - r i c h (Turekian and Wedepohl, 1961) and host most of the n i c k e l deposits i n the study area (see below). Tectonic Belt R e l a t i v e d e n s i t i e s of commodity occurrences are discussed by S i n c l a i r , et a l . , 1977.  They are used here to examine r e l a t i o n s h i p s between t e c t o n i c  environment and m i n e r a l i z a t i o n as characterized by metals and deposit types.  105 R e l a t i v e d e n s i t i e s i n d i c a t e how d e n s i t i e s w i t h i n a p a r t i c u l a r sub-area (or b e l t ) compare w i t h those of the e n t i r e area.  The mineral p o t e n t i a l f o r each  b e l t i s thereby o u t l i n e d by abundances of metals and deposit types i n the belts.  The procedure f o r determining r e l a t i v e d e n s i t i e s i s as f o l l o w s :  1)  I n d i v i d u a l b e l t d e n s i t i e s are determined by d i v i d i n g the number of occurrences of each metal or deposit type i n each b e l t by the area (a planimeter measurement) of each belt.  2)  Belt d e n s i t i e s are divided by those of corresponding metals and deposit types f o r the e n t i r e area.  3)  Resulting r e l a t i v e d e n s i t i e s are evaluated; those approaching 1.00 (1.90-1.10) are considered average, lower values i n d i c a t e lower than average d e n s i t i e s of occurrences, and higher values i n d i c a t e a high concent r a t i o n r e l a t i v e to the e n t i r e area.  Table 4-3 i s a comparison between Coast P l u t o n i c B e l t metal occurrence d e n s i t i e s of the present study area and those of the B r i t i s h 2 Cordillera.  Columbia  Values f o r many metals from the present study are two to  three times greater p r i m a r i l y because a l l metals i n each deposit were counted i n t h i s study, whereas S i n c l a i r , et a l . , 1977, counted only the f i r s t - r e p o r t e d metal.  On t h i s b a s i s , the d e n s i t i e s of copper, molybdenum  and tungsten occurrences i n t h i s study are probably representative of the e n t i r e C o r d i l l e r a , whereas cobalt, n i c k e l , a r s e n i c , s i l v e r , lead and espe c i a l l y zinc occurrences  are much denser; density values of antimony and  gold are r e l a t i v e l y low i n the study area. Factors which might lead to d i s t o r t e d values include cover m a t e r i a l s and e x p l o r a t i o n density. A l l u v i a l deposits ( i . e . , Fraser River d e l t a ) and s i g n i f i c a n t bodies of water ( i . e . , Howe Sound, Harrison Lake) have been The Coast P l u t o n i c Belt of the B r i t i s h Columbia C o r d i l l e r a includes the e n t i r e study area except the Eagle P l u t o n i c B e l t , therefore the area of the Spuz zum P l u t o n i c B e l t was included wxth that of the Coast P l u t o n i c Belt m c a l c u l a t i n g d e n s i t i e s f o r the present study area which appear on Table 4-3. The Cascade Belt (Figure 1-1) was a l s o included i n c a l c u l a t i o n s of the B r i t i s h Columbia C o r d i l l e r a , but i t s e f f e c t i s assumed to be minimal.  TABLE 4-3.  COMPARISON OF COAST PLUTONIC BELT DENSITIES OF THE PRESENT STUDY AREA AND OF THE CORDILLERA OF BRITISH COLUMBIA 1  Number of deposits; present study  Deposits/1,000 Km present study  2  Deposits/1,000 Km B.C. C o r d i l l e r a  2  Present study/ B.C. C o r d i l l e r a  Co  2  .12  .03  4.0  Ni  12  .70  .11  6.4  Cu  106  6.21  2.20  2.8  Zn  38  2.23  As  1  .06  .01  6.0  Mo  25  1.46  .52  2.8  Ag  44  2.58  .55  4.7  Sb  2  .12  .10  1.2  W  4  .23  .07  3.3  Au  38  2.23  2.05  1.1  Pb  17  1.00  .21  4.8  C o r d i l l e r a n values are from S i n c l a i r , et a l . , 1977.  . 17  13.4  107 excluded from a r e a l c a l c u l a t i o n s ; remaining g l a c i a l and a l l u v i a l cover i s not believed by the w r i t e r to be s i g n i f i c a n t i n a f f e c t i n g c a l c u l a t i o n s (cf. S i n c l a i r , et a l . , 1977).  The only major item not considered i s f o r e s t  cover; i t undoubtedly v a r i e s between b e l t s , but i s not dealt with e a s i l y . Density of exploration could d i s t o r t values because the northern  one-  t h i r d of the area i s not e a s i l y a c c e s s i b l e except f o r roads along the Fraser River and between Squamish and Pemberton. "The  Coast and Spuzzum  P l u t o n i c Belts are probably the most affected by poor access, but p r e v a i l i n g opinions that p l u t o n i c terranes have low mineral p o t e n t i a l have also  con-  3  t r i b u t e d to low occurrence d e n s i t i e s i n these b e l t s .  To check i f low  density values i n p l u t o n i c terranes are r e a l , the Coast and Spuzzum P l u t o n i c B e l t s were subdivided  i n t o areas underlain by p l u t o n i c rocks and areas  underlain by pendant rocks.  Resulting density values f o r the Coast P l u t o n i c  Belt are commonly high i n pendant rocks and low i n p l u t o n i c rocks, suggesting that perhaps d e n s i t i e s are r e f l e c t i o n s of both exploration and  min-.  eral potential.  low,  Values f o r the Spuzzum P l u t o n i c B e l t are c o n s i s t e n t l y  with the exception of n i c k e l and magmatic values f o r i n t r u s i v e rocks.  It is  possible that low d e n s i t i e s r e f l e c t poor exploration here, but mineral p o t e n t i a l i s also expected to be low, as discussed  below.  Separate examination of each t e c t o n i c b e l t serves to describe each i n terms of metals and deposit types which characterize i t ; density  distri-  butions of i n d i v i d u a l metals and deposit types can then be studied to examine the behavior of each metal and deposit type across the area. Figures 4-5a,b and 4-6a,b show that i n t r u s i o n s of the Coast P l u t o n i c Complex have a marked d i l u t i o n e f f e c t of density c a l c u l a t i o n s .  The area underlain  by p l u t o n i c rocks with l i t t l e or no reported m i n e r a l i z a t i o n makes up such a 3  The f a c t that a good p o r t i o n of the Coast P l u t o n i c Belt as close as 20 miles to Vancouver has not been mapped i n any d e t a i l also has not encouraged prospecting.  108 , c ml  c E  a  n  -2 _S  3  c  li  ll"  CL M  lo  ca  3-  a. CO  i *  c  ca « o CO  >1/->C0  O  (0  CO £  _£  CP  O f ~  0) al  4)  N O  - CO a —1  £ w  =E  £  0J CX3 VJ  "c o  «J CO  UJ  2i-  3*7 Gcopper  e n u m  Gold  ver  H  Lead  Z im o  Figure 4-5a.  R e l a t i v e d e n s i t i e s of copper, molybdenum, gold, s i l v e r , lead and z i n c with respect to t e c t o n i c b e l t s and s u b d i v i s i o n s . Bar widths are p r o p o r t i o n a l to b e l t areas. Only r e l a t i v e dens i t i e s greater than two (dashed l i n e ) a r e considered s i g n i f i c a n t . Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  109  i o  O  o  OS 0 0  HP  ca -a  (0  e J 1°" «a. -p <u i s CO  3  -—  US  N  _p  N  TO  I u II O-M3  CO  CQ  (/"ICQ  o  ;*2 vi . ICO OT  § «i  £ o  o  fi  «£ -a to  CQ c O-  o UJ  3 2-  1 Nick,  Irov\  Figure 4-5b.  R e l a t i v e d e n s i t i e s of n i c k e l , i r o n , antimony and tungsten with respect to t e c t o n i c b e l t s and s u b d i v i s i o n s . Bar widths are p r o p o r t i o n a l to b e l t areas. Only r e l a t i v e d e n s i t i e s greater than two (dashed l i n e ) are considered s i g n i f i c a n t . Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent dep-; o s i t s w i t h production records; blank bars represent showings, prospects and developed prospects.  110  *  2  "C °  O "oi  a: -g g "5  I o£  d5 ti ca CO  -a  «1  c a)  I ° CQ  CL. £  N  ^» oM  ID.  «"  !£5  Q3 <u -a co o tn ro O  al  £  CO  C  D-  CO  5  H32  1  3 5-  3  2  Skarn  10 9-  8  765VI 3-  z1-  Vol cahoqeruo Figure 4-6a.  R e l a t i v e d e n s i t i e s of magmatic, porphyry, skarn and volcanogenic deposits with respect to t e c t o n i c b e l t s and s u b d i v i s i o n s . Bar widths are p r o p o r t i o n a l to b e l t areas. Only r e l a t i v e d e n s i t i e s greater than two (dashed l i n e ) are considered s i g n i f i c a n t . Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  Ill  o c "5 g  0  c -oo -  CD  -a i  to  0  1  O -  • s  so  1  «i  £  -4J  c  »  £ -e  3 N  CO  £  •  „ a.« ' el  ,  I  £«i  =>a  -a  TO  o  CO  |</)£fl O  CP 3 o V  e) C -a  La  c o -tf  CO  :±2 ca0) o '£ o <1 cr< w UJ  •  7^ Vein 5H «»•  31 H ear  ]jissewi\r\a4iecl  if  1  73 f  •  assivs  Figure 4-6b.  R e l a t i v e d e n s i t i e s of v e i n , shear, disseminated and massive deposits with respect to t e c t o n i c b e l t s and s u b d i v i s i o n s . Bar widths are p r o p o r t i o n a l to b e l t areas. Only r e l a t i v e dens i t i e s greater than two (dashed l i n e ) are considered s i g n i f i cant. Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  large p o r t i o n of the study area that a l l b e l t s without s i g n i f i c a n t plutonism appear h e a v i l y mineralized i n comparison.  Since t h i s i s considered  an  important outcome of r e l a t i v e density c a l c u l a t i o n s , values have not been r e c a l c u l a t e d to compensate.  An a l t e r n a t i v e approach has been to regard as  s i g n i f i c a n t only those values approaching or exceeding an a r b i t r a r i l y chosen value of  2.00.  A metal or deposit type which i s reported r a r e l y w i l l produce an extremely high r e l a t i v e density value f o r the u n i t s i n which i t occurs; a d i f f e r e n c e of one or two samples w i l l cause an u n r e a l i s t i c v a r i a t i o n i n values.  Such extreme cases include the f o l l o w i n g commodities and deposit  types (numbers i n parentheses are numbers of occurrences); uranium (1), cadmium (1), cobalt (2), bismuth (2), arsenic (3), tungsten (6), antimony (7), volcanogenic  (2), and massive (5).  R e l a t i v e d e n s i t i e s are not consid-  ered f o r the foregoing categories except as i n d i c a t o r s of the presence of a metal or deposit type; uranium, cadmium, c o b a l t , bismuth and arsenic are not discussed f u r t h e r . M i n e r a l i z a t i o n C h a r a c t e r i z i n g Tectonic B e l t s Table 4-4 summarizes information derived from histograms of Figures 4-5a,b and 4-6a,b by c h a r a c t e r i z i n g each t e c t o n i c b e l t according to metals, deposit types and numbers of major deposits. The Hozameen Basin and Coast P l u t o n i c B e l t pendants have the highest p o t e n t i a l f o r the greatest v a r i e t y of metals and deposit types, but the concentration of producers and major deposits i n Coast P l u t o n i c B e l t pendants shows a much greater p o t e n t i a l f o r l a r g e , producing deposits.  The Ladner  Trough also e x h i b i t s a v a r i e t y of metal concentrations mainly i n veins and (associated?) shears; the number of producers here i s almost as high as i n Coast P l u t o n i c B e l t pendants.  TABLE 4-4. Tectonic B e l t  CHARACTERIZATION OF TECTONIC BELTS Deposit Type(s)  Metals  Maj or Deposits  Coast P l u t o n i c Belt intrusions Coast P l u t o n i c Belt pendant rocks Spuzzum P l u t o n i c Belt intrusions  Fe,Zn,Cu,Ag,Pb (Au)  1  Ni  shear, disseminated, skarn (volcanogenic)^ magmatic  Spuzzum P l u t o n i c Belt pendant rocks Cascade B e l t Hozameen Basin Ladner Trough  (Fe,Mo,Ag,Pb) Ni,Au,Pb,Fe,Ag,Zn (Cu) Au,Pb,Zn,Ag  skarn disseminated, skarn, magmatic (massive) v e i n , shear  Eagle P l u t o n i c B e l t R e l a t i v e d e n s i t i e s of metals i n parentheses are nearly 2.00; other values are greater than I  2.50.  "Deposit types i n parentheses have very high r e l a t i v e d e n s i t i e s based on very few occurrences.  114 With the exception of r e l a t i v e l y abundant magmatic n i c k e l i n i n t r u s i o n s of the Spuzzum P l u t o n i c B e l t , t h i s s u b d i v i s i o n , plus Coast P l u t o n i c Belt i n t r u s i o n s , Spuzzum P l u t o n i c Belt pendants, and the Eagle P l u t o n i c B e l t , feature low r e l a t i v e d e n s i t i e s which are to be expected i n dominantly p l u t onic or highly metamorphosed terranes. The Cascade Belt e x h i b i t s moderate r e l a t i v e metal occurrence d e n s i t i e s ; no metal values g r e a t l y exceed 2.00. deposits.  Skarns overshadow a l l other types of  Perhaps intense deformation i s p a r t i a l l y responsible f o r r e l a -  t i v e l y low values i n t h i s b e l t . D i s t r i b u t i o n of Metals and Deposit Types among Tectonic Belts In the preceding s e c t i o n an o v e r a l l pattern was determined which d i s tinguished the Coast P l u t o n i c B e l t pendants, the Ladner Trough and the Hozameen Basin as areas of most abundant mineral occurrences.  The Cascade  Belt contains moderate occurrence d e n s i t i e s , and the remaining p l u t o n i c and metamorphic b e l t s have r e l a t i v e l y low occurrence d e n s i t i e s . common metals (gold, lead, z i n c , s i l v e r ; Figure 4-5a) d i s t r i b u t i o n s which r e f l e c t t h i s pattern of abundance.  A few of the  exhibit similar Minor v a r i a t i o n s  are as f o l l o w s : gold and lead are more common i n the Hozameen Basin and Ladner Trough than i n pendants of the Coast P l u t o n i c B e l t , but zinc shows the opposite r e l a t i o n s ; s i l v e r i s almost equally abundant i n a l l three areas. The behavior of these metals suggests that tectonic environment was not very s e l e c t i v e between them.  In other words, both precious and base metals occur  i n approximately the same manner i n a v a r i e t y of t e c t o n i c environments. Iron oxide and tungsten (Figure 4-5b) behave much l i k e zinc except that both are notably low or absent from the Ladner Trough.  Copper i s most common  i n Coast P l u t o n i c Belt pendants, and i s only s l i g h t l y enriched Hozameen Basin.  i n the  Antimony i s reported most commonly i n the Hozameen Basin  or Ladner Trough and i s reported r a r e l y i n Coast P l u t o n i c B e l t pendants.  115 Molybdenum I s not notably abundant In any b e l t .  R e l a t i v e abundances of  n i c k e l show s i g n i f i c a n t l y high values i n Spuzzum P l u t o n i c B e l t i n t r u s i o n s and the Hozameen Basin. Tectonic b e l t s show greater c o r r e l a t i o n w i t h deposit types (Figures 4-6a,b).  Vein, volcanogenic and massive deposits are p a r t i c u l a r l y abundant  i n the Ladner Trough, Coast P l u t o n i c B e l t pendants and Hozameen Basin, r e s pectively.  Shears, magmatic and disseminated deposits are each common i n  two b e l t s , and skarns are common i n three.  Porphyry deposits show no  s i g n i f i c a n t concentration i n any b e l t . Host Rock Formation Figure 4-7 records the t o t a l number of deposits reported i n each mineralized u n i t of the study area; the Ladner, Hozameen and Gambier Groups, 4 and the Harrison Lake Formation stand out as the best-mineralized u n i t s . Two major deposits, Aurum (HNW-3) and Canam (HSW-1), and many producers i n the Ladner Group lend even more importance to i t as a host f o r m i n e r a l i z a t i o n . Considering the many occurrences deposits i s notable.  i n the Hozameen Group, the lack of major  The Gambier and Gambier? Groups together account f o r  an abundance of m i n e r a l i z a t i o n (on a l l scales) exceeding that of the Ladner Group; therefore, the Gambier? Group pendants are worthy of close examination.  L i k e the Hozameen Group, the Harrison Lake Formation has yet to  produce a major deposit, but u n l i k e the Hozameen Group, m i n e r a l i z a t i o n i n the Harrison Lake Formation has warranted considerable recent a t t e n t i o n . Major m i n e r a l i z a t i o n i n the Giant Mascot U l t r a m a f i t e i s not only a unique occurrence i n the study area, but also among ultramafic-hosted mineral deposits throughout the world ( N a l d r e t t , 1973). _  The area underlain by Coast P l u t o n i c i n t r u s i o n s i s so large that even uncommon m i n e r a l i z a t i o n can amount to a large number of deposits which w i l l , consequently, overshadow a l l other u n i t s when compared on a scale of t o t a l occurrences. High numbers of occurrences i n some non-plutonic u n i t s may a l s o be r e f l e c t i o n s of a r e a l abundance.  116  Figure 4-7.  T o t a l number of occurrences i n each m i n e r a l i z e d geologic u n i t of the study area (host u n i t s are known f o r 77% of a l l deposits i n the study area). Roman numerals i d e n t i f y t e c t o n i c b e l t s (see Table 2-1). T r i a n g l e s i d e n t i f y major deposits of Table 4-1; dense s t i p p l e s represent deposits w i t h production records; sparse s t i p p l e s represent showings, prospects and developed prospects.  117 D i s t r i b u t i o n of Deposit Types arid Metals Among Host Rock Formations The d i s t r i b u t i o n of i n d i v i d u a l metals and deposit types among host rock formations {Figures 4-8 and 4-9a,b) are s i g n i f i c a n t only i f they d i f f e r from that of t o t a l deposits (Figure 4-7). The abundant m i n e r a l i z a t i o n i n the Ladner Group i s a r e f l e c t i o n of v e i n deposits; other deposit types do not e x h i b i t t h i s degree of prominence i n any p a r t i c u l a r formation.  The presence of shears i n the Gambier Group,  disseminated deposits i n the Harrison Lake Formation, porphyries i n the Coast P l u t o n i c Complex, and the apparent absence of volcanogenic deposits i n units other than those of Coast P l u t o n i c Belt pendants i s notable. The only differences between d i s t r i b u t i o n patterns of t o t a l occurrences and of copper occurrences (Figure 4-9a) are that l e s s than one h a l f the Ladner Group deposits carry copper values.  This i s a s i g n i f i c a n t l y low  value when one considers that 73 percent of the deposits i n the study area contain copper.  A major copper deposit, Canam (HSW-1), i n the Ladner Group  stands out almost as a c o n t r a d i c t i o n to these r e l a t i v e l y low copper values. Gold and s i l v e r behave s i m i l a r l y , both r e f l e c t i n g t o t a l abundances shown i n Figure 4-7, w i t h minor exceptions.  Coast P l u t o n i c B e l t i n t r u s i o n s  show very low values f o r both, and gold occurrences are s l i g h t l y more abundant i n the Hozameen and Ladner Groups than are those of s i l v e r , which i n turn are more common than gold i n the Cascade B e l t . The major d i s t i n c t i o n between lead and zinc (Figure 4-9b) i s that lead i s minor i n Coast P l u t o n i c B e l t pendants, but zinc i s r e l a t i v e l y abundant. Both metals are uncommon i n Coast P l u t o n i c B e l t i n t r u s i o n s , but are abundant i n both the Hozameen and Ladner Groups. The d i s t r i b u t i o n of molybdenum mirrors that of porphyry deposits, but although molybdenum occurrences are more abundant than any other metal i n Coast P l u t o n i c B e l t i n t r u s i o n s , the density of these occurrences i s not high.  III  3<h  IV  V  VI  3<h  V,em  20'  v  VI  II  in IV  II  Porphyry  2W  X«<tfV  10-  43  EL  4^4 Shear  Lfe—J  X=83%  Skarn X-87%  Disseminated  X=<?0%  TO 01  1»<5 ^ O  lioS £ ^  u  tl <° O  o  ^  sgH-J}  1  43 ass/vg  5-H  X=80%  4=t  x =  >qmalic Jo 1°/  J  a i %  \/oh canogemc.  X=  1-1.3 S-S'c j;.y2-is  100%  u a J '" » n «  H  c  - C  3  C2H  a  O -+>  o n  o  o host rock u n i t . "X" i s the Figure 4-8. Number of occurrences of each deposit typ e w i t h respect to percent of t o t a l deposits of each deposit type f o r which host rock unit i s known. Roman numerals i d e n t i f y tectonic b e l t s (see Tab le 2-1). Triangles i d e n t i f y major deposits of Table 4-1; dense s t i p p l e s represent depos i t s w i t h production records; spars e s t i p p l e s represent showings, prospects and develop ed prospects.  oo  Ill V  VI  30J  IV  II  c  Gold  BY  X=84%  x=8a%  20-1  10-  Moiybdenumlo. X=81%  43d 4S£ 1-2 i - S S t « « t ! •5  3 .S ~u LC  £<3  OE  5  8  in  s 5 2S»s-?-5-* 21*2 s I oi ul o — c  v  «.3 jTS-s ^ 5  S =S  3 u  CSHU  <0  CO  Figure 4-9a.  N —'  £  <3  .3  CJ  C_>  Number of occurrences of copper, molybdenum, gold and s i l v e r with respect t o host rock u n i t . "X" i s the percent of t o t a l deposits of each metal f o r which host ro ck unit i s known. Roman numerals i d e n t i f y tectonic b e l t s (see Table 2-1). Triangles i d e n t i f y major deposits o f Table 4-1; dense s t i p p l e s represent deposits with product ion records; sparse s t i p p l e s represent showings, prospects and developed prospects.  120  III  IV  II  Lead  x=<?i%  is -  z  mc  X=<?0%  m  r r  X=7S%  JE3-  I  imoh  Tunqsien x=ieo%  Nickel x=a6%  K  JC  -J  •5s  <n  J  CI W  g  >  eg  3 $J-  u  t>5 " J  D  o  r  2  -c o  (0  i  £ n  3  3:  s  -P  CO  v  Ul  to  cJ _5 (o 3 : <o ro 3 ^ - *  s  ••3 S*5.s^»u 3  <3  o  Figure 4-9b.  Number of occurrences of lead, z i n c , i r o n , antimony, tungsten and n i c k e l with respect to host rock u n i t . "X" i s the percent of t o t a l deposits of each metal f o r which host rock u n i t i s known. Roman numerals i d e n t i f y t e c t o n i c b e l t s '(see Table 2-1), T r i a n g l e s i d e n t i f y major deposits of Table 4-1; dense s t i p p l e s represent deposits with production records; sparse s t i p p l e s represent showings, prospects and developed prospects.  121 M i n e r a l i z a t i o n C h a r a c t e r i z i n g Host Rock Formations Host rock formations are discussed as members of the t e c t o n i c b e l t s i n which they occur, thereby f u r t h e r c l a r i f y i n g occurrence d i s t r i b u t i o n s w i t h i n tectonic b e l t s .  Figure 4-7 serves as an o u t l i n e f o r d i s c u s s i o n of r e l a t i v e  abundances between formations.  Figures 4-8 and 4-9a,b provide information  on the more weakly mineralized u n i t s not discussed i n d e t a i l below. Eagle P l u t o n i c B e l t .  Deposits i n the Eagle P l u t o n i c B e l t occur i n both  the N i c o l a Group and the Eagle Complex (Figure 4-10a); no production has been recorded i n t h i s b e l t .  Considering the 99 percent dominance of p l u t o n i c  outcrop over v o l c a n i c (Nicola) outcrop, the f a c t that the number of occurrences are equal i n both u n i t s suggests that the N i c o l a Group i s w e l l mineralized.  In f a c t , m i n e r a l i z a t i o n on the Princeton Map  Sheet (92H, East  Half) i s reported to occur most commonly i n the N i c o l a Group (Rice, 1960). Only veins are reported i n the N i c o l a Group i n the study area, f i v e of them i n the Jim K e l l y Creek Camp, whereas the Eagle Complex contains four d i f f e r e n t deposit types dominated by porphyries.  Recognized metals do not  vary much between u n i t s , but N i c o l a Group veins contain more gold, and porphyries i n the Eagle Complex contain molybdenum m i n e r a l i z a t i o n not found i n the N i c o l a Group. Ladner Trough.  Of the seven"* formations i n the Ladner Trough, only the  Ladner Group (Figure 4-10a) contains abundant mineral occurrences; the Pasayten Group, Needle Peak Pluton and Invermay Stock contain few deposits. The Ladner Group i s dominated by veins of the Ladner Gold B e l t and Summit Camp, one-third of which are producers.  However, the two major  deposits, Canam (HSW-1) and Aurum (HNW-3), are porphyry and  disseminated  ^Only s i x u n i t s are recognized on the time-space p l o t (Figure 2-2), but a small mineralized p l u t o n , the Invermay stock, i s an a d d i t i o n a l u n i t considered i n t h i s d i s c u s s i o n . The age of t h i s stock i s probably equivalent to the 84 Ma pluton two kilometers north, which straddles the Hozameen F a u l t .  E-atjIe Plut-cmicBelt  . Cc  £  n  u  inn  III  8 depasih*  t  Figure 4-10a.  Hozameen Basin  "3  8 deposits  S  -\  24 deposits |  Eagle.  #02  Complex.  Group  20  <r  AJicola Group  JL  as  h  10  4$  E  5 5£  Number of occurrences i n host rock units of the Eagle Plutonic B e l t , Ladner Trough Hozameen Basin and Cascade B e l t , with respect to metal content and deposit type ° Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with proauction records; blank bars represent showings, prospects and developed prospects  J3  123  types, r e s p e c t i v e l y .  Precious metal occurrences are more dominant than  base metals, and the only uranium occurrence i n the area i s found here (Canam). Hozameen Basin.  Deposits i n the Hozameen Basin occur i n the abundant  Hozameen Group (Figure 4-10a).  A v a r i e t y of deposit types i s present, con-  centrated i n the 10-Mile and 23-Mile Creek Camps; veins are only s l i g h t l y more common than other types.  The most commonly reported metal i s gold,  but copper and s i l v e r are almost as common; zinc and lead are also reported with moderate frequence. Cascade B e l t .  The only production was from v e i n s .  Mineral occurrences are most common i n the C h i l l i w a c k  and Mt. Barr b a t h o l i t h s , and the C h i l l i w a c k Group (Figure 4-10a).  Other  formations w i t h few occurrences are Custer Gneiss, C u l t u s , Chuckanut and Skagit Formations. The C h i l l i w a c k and Mt. Barr b a t h o l i t h s are grouped together because they are s i m i l a r i n age, s e t t i n g and m i n e r a l i z a t i o n .  Deposits are e i t h e r  veins or porphyries; metals are copper, molybdenum, s i l v e r and gold.  Skarns  characterize the C h i l l i w a c k Group; copper and s i l v e r stand out as the most common metals.  Minor production i n the Cascade B e l t i s r e s t r i c t e d to the  C h i l l i w a c k Group and Chuckanut Formation. Spuzzum P l u t o n i c B e l t .  M i n e r a l i z e d u n i t s of t h i s b e l t are the Scuzzy  and Spuzzum plutons, and the Giant Mascot U l t r a m a f i t e . Although the number of deposits i s s m a l l , the magmatic nickel-copper orebodies of the Giant Mascot U l t r a m a f i t e form one of the major deposits i n the study area (HSW-4). Coast P l u t o n i c B e l t .  The Twin Islands and Bowen I s l a n d Groups, and  Echo I s l a n d , Agassiz P r a i r i e and Cheakamus Formations contain very few deposits.  Figure 4-10b i l l u s t r a t e s m i n e r a l i z a t i o n i n the f i v e formations  124  Coast Plutonic Complex sn a-  E  21  I"  Japoaitis.  *3  T  lev taro QJ  up  20 vn  ui a-  fa  AA  3  .10 d a  jamDieir? Group c5  .yj  5 «! <=>  JL  11-  1M jnyos'i-ls  Harrison  10 .of  formal  lake, ion  IDS  -Q-  /-7re /.a/re IN  Figure 4-10b.  cT  Number of occurrences i n host rock u n i t s of the Coast P l u t o n i c Belt with respect to metal content and deposit type. T r i a n g l e s i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent depo s i t s w i t h production records; blank bars represent showings, prospects and developed prospects.  125  discussed below. The F i r e Lake Group contains only gold-copper veins i n the F i r e Lake Camp, but other u n i t s are more d i v e r s i f i e d i n t h e i r deposit content. M i n e r a l i z a t i o n i n the Harrison Lake Formation most commonly i s disseminated, but minor production was from a v e i n and a volcanogenic deposit (Providence, HNW-2, and Seneca, HSW-13, r e s p e c t i v e l y ) .  Copper and zinc dominate other  metals, although s i l v e r , gold and lead a l s o occur. The Gambier Group i s divided i n t o two sections because the two mine r a l i z e d pendants to the north (referred to as "Gambier? Group") have not been correlated p o s i t i v e l y with the Gambier Group.  The number- of producers  i n the southern pendants i s very low, but includes the major volcanogenic deposit at B r i t a n n i a (G-3), whose presence alone c l a s s i f i e s i t s host as the best mineralized u n i t i n the e n t i r e study area.  Vein deposits, which dom-  inate the area i n number, are not reported from the Gambier Group i n the south.  As l i t t l e as ten years ago, t h i s would not have been the case, as  B r i t a n n i a was then considered a v e i n .  I t i s p o s s i b l e that other deposit  types (except porphyries) might be volcanogenic accumulations McVicar, G-6) which have not yet been recognized as such.  (especially  Copper i s by f a r  the most commonly reported metal; zinc and s i l v e r also are reported f r e - ... quently. One or both of the northern pendants may be T r i a s s i c or J u r a s s i c , as discussed i n the previous chapter.  The percentage of producers i s high,  and one v e i n deposit i s major (Northair, J-130).  Metal d i s t r i b u t i o n s  resemble those of Gambier Group pendants discussed above except f o r the more abundant occurrence of lead and the presence of antimony and tungsten. Porphyries are the most common deposits i n i n t r u s i o n s of the Coast P l u t o n i c Complex; t h i s i s r e f l e c t e d i n metal d i s t r i b u t i o n s by dominant copper and molybdenum.  Moderate s i l v e r and gold reports are probably from  126 v e i n deposits which are the only other r e l a t i v e l y common type of mineralization.  Production i s low.  Host Rock Type Host rock types are known f o r 78 percent of the deposits i n the study area.  I n t r u s i v e , v o l c a n i c and sedimentary rocks are well-represented, but  metamorphic rocks are not discussed f o r two reasons: 1)  Only 15 deposits (out of 203 t o t a l ) report metamorphic host rocks; and  2)  Eight of those 15 occurrences are described as metavolcanic or metasedimentary, and can therefore be classed as v o l c a n i c or sedimentary.  I f a metal or type of deposit i s associated g e n e t i c a l l y with a p a r t i cular rock type, i t should be r e a d i l y apparent, regardless of c o i n c i d e n t a l occurrences i n other types.  Therefore, when more than one mineralized rock  type i s reported f o r a deposit, each i s recorded and given equal weight. The three major rock types are subdivided f u r t h e r as f o l l o w s : 1)  I n t r u s i v e rocks which i n c l u d e ^ a) b) c)  2)  Volcanic rocks which include a) b) c) d)  3)  intermediate to acid i n t r u s i o n s , u l t r a m a f i c i n t r u s i o n s , and dikes of any composition.  b a s i c v o l c a n i c rocks and greenstones ( i . e . , andesite, basalt), acid v o l c a n i c rocks ( i . e . , r h y o l i t e , d a c i t e ) , p y r o c l a s t i c v o l c a n i c rocks ( i . e . , t u f f , agglomerate, breccia) of unspecified composition,7 and u n c l a s s i f i e d v o l c a n i c and metavolcanic rocks.  Sedimentary rocks which include a) b) c)  c l a s t i c sedimentary rocks ( i . e . , shale, sandstone, conglomerate, b r e c c i a ) , limestone, and s i l i c e o u s ( i . e . , chert, q u a r t z i t e ) and u n c l a s s i f i e d sedimentary rocks.  With the exception of d i k e s , mafic i n t r u s i o n s were not reported to host m i n e r a l i z a t i o n i n the study area. A p y r o c l a s t i c rock whose composition i s known i s categorized by that composition.  Metals and deposit types are f i r s t examined below to review t h e i r d i s t r i b u t i o n among the three major rock types (Figure 4-11).  A l l histogram  d i s t r i b u t i o n s i n t h i s s e c t i o n are compared to mineralized rock type abundances f o r the study area shown i n Figure 4-12.  The apparent concentration  of mineral occurrences i n i n t r u s i v e rocks i s misleading, because the amount of p l u t o n i c outcrop i s much greater than e i t h e r v o l c a n i c or sedimentary g outcrop.  I f d e n s i t i e s of occurrences were determined f o r each rock type,  values f o r p l u t o n i c rocks would be very low; v o l c a n i c and sedimentary rocks ( e s p e c i a l l y b a s i c v o l c a n i c rocks and c l a s t i c sedimentary rocks, Figures 4-14 and 4-15) would e x h i b i t very high d e n s i t i e s . Subsequent discussion of rock types uses the more d e t a i l e d c l a s s i f i cations described above to characterize m i n e r a l i z a t i o n i n each host rock and further examine the behavior of metals and deposit types i n the smaller categories.  Figures 4-2 and 4-3 are used as i n d i c a t o r s of general abundances  for comparison of m i n e r a l i z a t i o n i n each rock type. D i s t r i b u t i o n of Metals and Deposit Types Among Host Rock Types Copper, molybdenum and n i c k e l e x h i b i t p r e d i c t a b l e d i s t r i b u t i o n patterns (Figure 4-11).  Copper occurrences are abundant i n every rock type, but  n i c k e l and molybdenum occurrences are associated p r e f e r e n t i a l l y with i n t r u s i v e rocks; other metals studied appear to occur p r e f e r e n t i a l l y i n v o l c a n i c and sedimentary rocks. Zinc, lead and antimony occurrences prefer v o l c a n i c over sedimentary rocks, zinc showing the most s i g n i f i c a n t preference.  Gold, s i l v e r and i r o n  oxides are more common i n sedimentary than v o l c a n i c rocks. Many v e i n occurrences are reported i n a l l rock types, but the density —  S i x t y - f o u r percent of the study area i s u n d e r l a i n by Eagle Complex, Coast P l u t o n i c Belt i n t r u s i o n s and Spuzzum P l u t o n i c Belt i n t r u s i o n s ; the remaining 36 percent i s occupied by both v o l c a n i c and sedimentary rocks, along with various plutons whose areas were not computed.  128  V  3 6 -  36-  36-  I 20-  20-  10-  10-  3Jr-  I V  Vein  Porphuru Xr-VrtV = 83% V lo-  am  Disse.mmai.ed  MaamaVlC  X"-100%  I  s-  Sli&ar  Ma5s'iv&  s-  X=60 /o e  Vol  X=ioo%  I  So-  50-  V  10-  1  I  30-  hi30-  30-  20  .A' Copper X»83% X 30  SilvsY X=80%  1<H  irmc  Lead  X=80%  10-  M o l u U enum  X«88% Figure 4-11.  Tor* X=<)0%  (U y=ioo7o"  ~Tvmy4;e,Y\ X*\D07*  Number of occurrences of each metal and deposit type with respect to i n t r u s i v e ( I ) , v o l c a n i c (V) and sedimentary (S) host rock types. "X" i s the percent of t o t a l deposits of each metal or deposit type f o r which host rock type i s known. Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  129  10. 80-  1  7fl6050HO30-  2010-  A 1*1  ~T~"  a) o ' :r» 1  ?  u  c  on Figure 4-12.  T o t a l number of occurrences i n i n t r u s i v e , v o l c a n i c and s e d i mentary host rocks (host rock type i s known f o r 73% of a l l deposits i n the study area). T r i a n g l e s i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  130 of occurrences i n i n t r u s i v e rocks i s very low.  Sedimentary rocks favor  v e i n m i n e r a l i z a t i o n s l i g h t l y more than v o l c a n i c rocks, but the l a t t e r host the only major v e i n deposit, Northair (J-130). Porphyry and Magmatic deposits are p a r t i c u l a r l y abundant i n t h e i r g e n e t i c a l l y associated i n t r u s i v e host rocks.  The occurrence of a major  porphyry deposit, Canam (HSW-1), i n sedimentary rocks i s unusual. A preference by skarn deposits f o r sedimentary rocks i s p r e d i c t a b l e , as calcareous sedimentary rocks are commonly a f f e c t e d by contact metasomaT.. tism. The f a c t that the volcanogenic deposits, B r i t a n n i a (G-3) and Seneca (HSW-13) are i n v o l c a n i c rocks i s almost a matter of d e f i n i t i o n , although d i s t a l sedimentary rocks are also p o t e n t i a l hosts.  With only two reported  deposits of t h i s type, f u r t h e r d i s c u s s i o n i s not p o s s i b l e . Massive depo s i t s a l s o lack a s u f f i c i e n t data base f o r d e t a i l e d a n a l y s i s . Shear and disseminated deposits occur i n a l l rock types, but are most common i n v o l c a n i c rocks:  the only disseminated deposit to produce, A s t r a  (J-45), i s i n v o l c a n i c rocks.  I t i s p o s s i b l e that these deposits are  g e n e t i c a l l y r e l a t e d to volcanism, representing syngenetic accumulations. The presence of a major disseminated deposit, Aurum (HNW-3), i n sedimentary rocks i s unusual. M i n e r a l i z a t i o n C h a r a c t e r i z i n g Host Rock Types Figures 4-13 through 4-15 i l l u s t r a t e the d i s t r i b u t i o n of metals and deposit types among s p e c i f i c rock types c h a r a c t e r i z i n g i n t r u s i v e , v o l c a n i c and sedimentary rocks.  The height of each histogram i s equivalent to the  number of deposits i n each rock type so that values may also be estimated as percentages. I n t r u s i v e Rocks (Figure 4-13).  The high percentage of porphyry deposits  131 Intermediate  lo  flc'id  Jnt  rusive Rock  fa)  (b)  (c)  Fe'Co'ff; WihflslT.fljCd'Sfc WfluPI, Bi U  C ~SZ  & -o  Jc.  -p  to  Figure 4-13.  £  O  <4  <o  *—  3">  E  ro  :T> c  QJ  o c ro _o  Number of occurrences i n (a) intermediate to a c i d i n t r u s i v e rocks, (b) u l t r a m a f i c rocks, and (c) d i k e s , with respect to metal content and deposit type. Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits w i t h production records; blank bars represent showings, prospects, and developed prospects.  132 i n intermediate to acid i n t r u s i v e rocks has r e s u l t e d i n an unusually high abundance of molybdenum occurrences i n these rocks.  S i m i l a r l y , the high  incidence of magmatic deposits i n u l t r a m a f i c rocks c o r r e l a t e s d i r e c t l y with the high proportion of n i c k e l occurrences i n u l t r a m a f i c rocks, to the exclusion of a l l other metals except gold and s i l v e r .  Vein and disseminated  deposits i n intermediate to acid i n t r u s i v e rocks probably carry the v a r i e t y of metals which i s not present i n u l t r a m a f i c rocks. Occurrences which report dikes as the predominant mineralized host rock most commonly contain copper, gold and/or s i l v e r .  Dikes do not show a  preference f o r any p a r t i c u l a r type of deposit. Volcanic Rocks (Figure 4-14).  Metal abundances i n basic v o l c a n i c rocks  resemble general abundances of metals i n the study area, except that basic v o l c a n i c rocks appear to contain an above average proportion of z i n c occurrences and, to a l e s s e r extent, lead.  This trend i s even more evident  i n a c i d i c and p y r o c l a s t i c v o l c a n i c rocks where z i n c i s as common as copper. The number of lead occurrences i n t h i s category i s close to that of the precious metals; normally lead i s only one-half to one-third as common as precious metals.  The absence of n i c k e l and few reports of molybdenum i n  a l l v o l c a n i c rocks i s to be expected i f concentrations of these metals o r i g i n a t e w i t h i n t r u s i v e rocks.  Antimony most often occurs i n v o l c a n i c  ( e s p e c i a l l y b a s i c v o l c a n i c ) rocks. Although many veins occur i n v o l c a n i c rocks, disseminated deposits are as common.  The high proportion of deposits r e p o r t i n g v e i n , shear, d i s -  seminated and massive deposits, and the presence of the only recognized volcanogenic deposits i n the study area suggest that occurrences i n v o l c a n i c rocks are dominantly of volcanogenic o r i g i n .  Veins, disseminations and  massive s u l f i d e s are c h a r a c t e r i s t i c of volcanogenic deposits, and shears might e a s i l y describe portions of a deformed volcanogenic deposit.  Skarns  133  5 and  Green  si, oh&s  Acid Volcanic Rocks -10-  - s -  (b)  i}—i  7t/ff, Aqalom&raie  and Volcanic Breccia  Unclassified and /Helamorphos&J i  i  Volcanic Rocks  i  -10- 5  Fe Co Ni Cu 2n flsfl, % CJ S i W /.»PA Bi U  -  _  s. -o CO  Figure 4-14,  «  O  in  (o TO  c  3 ^  O  c  •a") o o  Number of occurrences i n (a) b a s i c v o l c a n i c rocks and greenstones, (b) acid v o l c a n i c rocks, (c) t u f f , agglomerate and v o l c a n i c b r e c c i a , and (d) u n c l a s s i f i e d and metamorphosed v o l c a n i c rocks, with respect to metal content and deposit type. T r i a n g l e s i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production records; blank bars represent showings, prospects and developed prospects.  134 and porphyry deposits do not appear to favor v o l c a n i c rocks. Sedimentary Rocks (Figure 4-15).  C l a s t i c sedimentary rocks report f a r  l e s s copper than i n t r u s i v e and v o l c a n i c rocks, but gold and s i l v e r are reported i n more than h a l f the deposits.  Despite the importance of precious  metals to c l a s t i c sedimentary rocks, only one major non-producing gold deposit, Aurum (HNW-3), i s present ( c f . the two major producing deposits with precious metals i n v o l c a n i c rocks; B r i t a n n i a , G-3, and N o r t h a i r , J-130). Other sedimentary rocks, on the other hand, are dominated by copper. With the exception of two n i c k e l occurrences i n limestone, n i c k e l and molybdenum are rare.  Iron i s commonly reported i n limestone, and the only  uranium occurrence i n the area i s i n c l a s t i c sedimentary rocks. Veins account f o r 74 percent of a l l deposits i n c l a s t i c sedimentary rocks, and many were producers, but disseminated and porphyry types host the two major deposits, Aurum (HNW-3) and Canam (HSW-1).  Skarn mineral-  i z a t i o n exceeds a l l other types i n limestone.  DEPOSIT DISTRIBUTION MAPS Appendix B contains a r e a l d i s t r i b u t i o n maps of deposit types and selected metals reproduced d i r e c t l y from Calcomp p l o t t e r output ( c f . S i n c l a i r , et^ a l . , 1978).  Outstanding physiographic features and t e c t o n i c b e l t s are  included f o r easy reference to Figure 1-2.  Observations  of deposit type  d i s t r i b u t i o n s are as f o l l o w s : 1) Magmatic deposits are noticeably c l u s t e r e d around Giant Mascot, as discussed p r e v i o u s l y . 2) Massive deposits (with one exception) are located i n the 10-Mile Creek Camp. 3)  Shear deposits are c l u s t e r e d a) around B r i t a n n i a and b) i n an area which combines deposits of two dominantly v e i n camps whose ages of m i n e r a l i z a t i o n are probably d i s s i m i l a r — Summit and Ladner Gold. Shears i n the Coast P l u t o n i c B e l t  135  CldSJlC  S £(jima)rfc a r t f  Limesi  Siliceous  F«Co/ViCu2n  Asd.  3rid  • a  Rocks  one  UncldssiPied  tL  -  S&dimaniaRock  S-  fljCjst wfl pb'oi'u  c  u  S  »- -a  S  CO  " 5 Kl » in  EST in in  Figure 4-15.  o _ to  .Co  £o- < on V  E  =5  Number of occurrences i n (a) c l a s t i c sedimentary rocks, (b) limestone, and (c) s i l i c e o u s and u n c l a s s i f i e d sedimentary rocks, w i t h respect to metal content and deposit type. Triangles i d e n t i f y major deposits of Table 4-1; s t i p p l e s represent deposits with production r e c o r d s ; blank bars represent showings, prospects and developed prospects.  136 are Intimately associated with disseminated and porphyry deposits, whereas the eastern c l u s t e r of shears i s notably devoid of both disseminated and porphyry occurrences. The opposite r e l a t i o n s h i p applies to shears and v e i n s , as the eastern shear deposits are s p a t i a l l y r e l a t e d to veins which are not reported i n the B r i t a n n i a area. 4)  Veins dominate the eastern one-third of the area, but are r a r e l y reported i n the Coast P l u t o n i c B e l t except at N o r t h a i r , F i r e Lake and P i t t Lake; no veins are reported west of 123° 30' west longitude. Vein deposits are not reported i n the v i c i n i t y of the known volcanogenic deposits, B r i t a n n i a and Seneca.  5)  Although porphyry deposits are evenly scattered among occurrences i n the eastern one-third of the area, they occur i n the Coast P l u t o n i c B e l t mainly i n an east-westtrending band from the Sechelt Peninsula to Harrison Lake. Porphyries are s l i g h t l y more dense around B r i t a n n i a than elsewhere. With one exception, no v e i n deposits occur i n t h i s band of porphyries.  6)  Disseminated deposits i n the Coast P l u t o n i c B e l t occur i n an arc extending northwest to southeast through N o r t h a i r , B r i t a n n i a , Harrison Lake and the 10-Mile Creek Camp; they surround the Seneca deposit.  7)  Skarns are most common i n the southeast corner of the area, and occur i n the Coast P l u t o n i c B e l t only near N o r t h a i r , on the Sechelt Peninsula, and s l i g h t l y north of Vancouver.  Metals do not generally e x h i b i t d i s t r i b u t i o n s as marked as those of deposit types.  To the contrary, most metal d i s t r i b u t i o n s are s i m i l a r to  that of the general abundance of deposits shown i n Figure 1-2, with minor deviations.  Some observations that can be made are as f o l l o w s :  1)  The d i s t r i b u t i o n of n i c k e l i s s i m i l a r to that of magmatic deposits. The c l u s t e r of n i c k e l deposits i s devoid of z i n c , s i l v e r , gold, lead and molybdenum occurrences.  2)  The d i s t r i b u t i o n of molybdenum i s s i m i l a r to that of porphyries. Only one deposit contains both molybdenum and l e a d , Canam (HSW-1).  3)  Copper, s i l v e r , gold and z i n c are d i s t r i b u t e d according to the general abundance of deposits, only gold e x h i b i t i n g a marked preference to eastern deposits.  4)  Lead i s reported p r i m a r i l y i n the southeastern corner of the area and l e s s commonly i n the Northair D i s t r i c t . Only scattered occurrences appear elsewhere, and no lead occurs west of 123° 30' west longitude.  137 The f o l l o w i n g information i s derived from multi-commodity d i s t r i b u t i o n s of Maps B-26  through  occurrence  B-30:  1)  Where precious metals occur w i t h molybdenum, s i l v e r i s i n v a r i a b l y present.  2)  Lead i s commonly reported w i t h s i l v e r ; with one exception, s i l v e r i s absent from lead deposits only i n small showings or prospects which may not have assayed f o r s i l v e r .  3)  Lead occurs most commonly w i t h zinc east of Hope.  4)  Gold occurs without s i l v e r only east of P i t t and F i r e Lakes.  Commodity d i s t r i b u t i o n maps each present every occurrence of a commodity according to deposit s i z e and ranking among other metals i n each deposit.  Examination of these maps reveals that d i s t r i b u t i o n patterns  would have been considerably d i f f e r e n t f o r many metals had only f i r s t reported (or f i r s t - r a n k e d ) commodities been portrayed. commodity map  A first-ranked  f o r molybdenum would imply that none i s present i n the Coast  P l u t o n i c Belt whereas, i n f a c t , molybdenum occurrences are more common i n i n t r u s i o n s of t h i s b e l t than are occurrences of other metals studied. Since zinc i s r a r e l y reported as a f i r s t - r a n k e d commodity, t h i s r e l a t i v e l y common metal would not have shown up on such a map.  Similar variations  apply to lead, s i l v e r and copper; even i n c l u s i o n of second-ranked commod i t i e s w i l l not always lead to s a t i s f a c t o r y representation of the d i s t r i bution of a metal (cf. l e a d , z i n c ) .  SUMMARY A s t a t i s t i c a l examination of deposit c h a r a c t e r i s t i c s i n the study area has l e d to the f o l l o w i n g observations: 1)  Dominant metals, i n order of abundance of occurrences, are copper, gold, s i l v e r , z i n c , lead and molybdenum.  2)  Dominant deposit types, i n order of numerical abundances, are v e i n , porphyry and disseminated.  138 3)  The d i s t r i b u t i o n of metals among major and producing deposits generally r e f l e c t s t o t a l metal abundances.  4)  The d i s t r i b u t i o n of deposit types among major and producing deposits does not r e f l e c t t o t a l deposit type abundances. Porphyry, disseminated and magmatic deposit types are e i t h e r uncommonly present or uncommonly producers, and yet each i s host to a major deposit. The most abundant deposits w i t h the majority of producers i n the area are v e i n s , and yet only one major deposit i s a v e i n . Volcanogenic deposits have only been recognized i n the area twice, and yet one of these deposits, B r i t a n n i a , i s of c o l o s s a l proportions r e l a t i v e to other occurrences i n the area. A d d i t i o n a l discrepancies between major deposits and other factors include the f o l l o w i n g : a)  Seventy-four percent of a l l deposits i n c l a s t i c rocks are v e i n s , and yet the major deposits are disseminated (Aurum) and porphyry (Canam).  b)  Porphyries are s i n g u l a r l y dominant i n i n t r u s i v e rocks, and yet the only producing porphyry (Canam) i s i n sedimentary rocks.  c)  Disseminated and shear deposits dominate v o l c a n i c rocks, and yet the major, disseminated deposit i s i n sedimentary rocks (Aurum).  5)  Molybdenum occurs generally i n porphyry deposits i n i n t r u s i v e rocks.  6)  N i c k e l occurs generally i n magmatic deposits i n u l t r a m a f i c rocks whose d i s t r i b u t i o n i s centered around the Giant Mascot Ultramafite.  7)  Skarn deposits generally occur i n limestone.  8)  Intermediate to a c i d i n t r u s i v e rocks are poorly mineralized.  9)  Pendant rocks i n the Coast P l u t o n i c B e l t are w e l l mineralized.  10)  With the exception of the Cascade B e l t , geologic u n i t s across the area with considerable v o l c a n i c rocks are w e l l - m i n e r a l i z e d by v e i n , shear, disseminated and massive deposits.  11)  C l a s t i c sedimentary rocks a l s o report considerable m i n e r a l i z a t i o n , but only the Ladner Group reports a s i g n i f i c a n t number of occurrences.  12)  The most economically favorable host rock u n i t s i n the area are. the Gambier Group and the Ladner Group; each contain high numbers of occurrences and two major deposits.  139  5.  CONCLUSIONS AND METALLOGENY  The t e c t o n i c model presented b r i e f l y i n Chapter Two  implies the  presence of (at l e a s t ) two episodes of subduction which r e s u l t e d i n forma t i o n of the Cretaceous Coast P l u t o n i c Complex and the T e r t i a r y Cascade Belt.  Intense plutonism i n Cretaceous  time, c o l l i s i o n of the Coast P l u t o n i c  arc with the Intermontane arc i n mid-Cretaceous time, and considerable r i g h t - l a t e r a l movement along major f a u l t s i n T e r t i a r y time have s i g n i f i cantly disguised o r i g i n a l r e l a t i o n s h i p s i n the area.  In t h i s context, i t  becomes d i f f i c u l t not only to unravel the t e c t o n i c h i s t o r y , but to r e l a t e the metallogenic h i s t o r y to the t e c t o n i c framework. Examination of major deposits, d i s t r i c t s of s i g n i f i c a n t concentrations of deposits, and deposits with production records has served to describe the dominant areas of i n t e r e s t and r e l a t e them to the t e c t o n i c e v o l u t i o n of the area.  The r e s u l t s of the d e s c r i p t i v e work i n Chapter Three are  i l l u s t r a t e d on the time-space p l o t of Figure 2-2.  The d i s t r i b u t i o n of min-  e r a l i z a t i o n here implies that the great majority of deposits were formed (a) throughout the Coast P l u t o n i c B e l t and (b) s p a t i a l l y r e l a t e d to the Hozameen Fault during Cretaceous  c o l l i s i o n and plutonism.  This epoch of  m i n e r a l i z a t i o n includes the f i v e major deposits found i n the study area. Less abundant m i n e r a l i z a t i o n occurred i n Oligocene-Miocene time. As a t t r a c t i v e as t h i s model of two metallogenic epochs may be, i t i s i n part a b u i l t - i n r e s u l t of the manner i n which t h i s study was  undertaken.  Determination of the age of m i n e r a l i z a t i o n of many camps i s l i t t l e more than supposition; i f m i n e r a l i z a t i o n i s assumed to be epigenetic, i t i s also assumed to be the product of observed deformation or plutonism.  These  assumptions are believed by the author to be reasonable, although supportive evidence commonly i s l a c k i n g .  140 Major m i n e r a l i z a t i o n c h a r a c t e r i z i n g the Cretaceous episode i n c l u d e s : 1)  volcanogenic copper-zinc s u l f i d e deposition ( B r i t a n n i a ) i n volcano-sedimentary rocks of the Coast P l u t o n i c a r c ,  2)  formation of a g o l d - s i l v e r - l e a d - z i n c v e i n (?; Northair) i n v o l c a n i c pendant rocks of the Coast P l u t o n i c B e l t ,  3)  magmatic nickel-copper s u l f i d e formation (Giant Mascot) i n the a x i a l metamorphic core of the Spuzzum P l u t o n i c B e l t ,  4)  i n t r o d u c t i o n of gold i n veins and disseminations (Ladner Gold) i n rocks adjacent to the deep-seated Hozameen Fault and serpentine b e l t , and  5)  formation of a copper-rich b r e c c i a pipe (Canam) i n sedimentary rocks adjacent to the Hozameen F a u l t .  Formation of copper-zinc s u l f i d e deposits (Harrison Lake D i s t r i c t ) p r i o r to Cretaceous time occurred during a c i d i c volcanism of the Middle J u r a s s i c Harrison Lake Formation.  M i n e r a l i z a t i o n might have occurred  during deposition of the Hozameen Group i n Upper Paleozoic time, but too l i t t l e i s known about these deposits to put much emphasis on t h i s suggestion. The a p p l i c a t i o n of s t a t i s t i c a l t a b u l a t i o n s to information accumulated on metal occurrences i n the study -area has revealed some i n t e r e s t i n g r e l a tionships.  Although major deposits r e f l e c t the general abundance of metals  i n the area, they do not correspond to the most, common deposit types. This i s unfortunately a poor r e f l e c t i o n of the c l a s s i f i c a t i o n scheme used i n t h i s study, as a l l of the major deposits (except Canam) are located i n areas where they should be expected to occur on the basis of geology surrounding metal occurrences.  and  For t h i s reason, a d e t a i l e d knowledge of  the geology and c h a r a c t e r i s t i c s of i n d i v i d u a l occurrences has proved i n valuable. The most notable r e s u l t s of the s t a t i s t i c a l study p e r t a i n to the c o n t r o l of host rock type over m i n e r a l i z a t i o n .  I n t r u s i v e rocks are s i n g -  u l a r l y characterized by molybdenum and n i c k e l s u l f i d e occurrences i n intermediate to acid v a r i e t i e s and u l t r a m a f i c rocks, r e s p e c t i v e l y .  The  141  source of n i c k e l corresponds to i t s inherently n i c k e l - r i c h host rock, and since molybdenum occurrences are r e s t r i c t e d to intermediate to acid i n t r u s i v e rocks, the source of t h i s metal also i s assumed to be i t s host intrusion. C l a s t i c sedimentary rocks p r i m a r i l y contain v e i n deposits with predominant precious metal (mainly gold) content.  However, t h i s abundance of  deposits i s r e s t r i c t e d to the Ladner Group, s p e c i f i c a l l y along the serpentine b e l t of the Hozameen Fault.  Gold deposits, therefore, are c o n t r o l l e d by  t e c t o n i c environment, not rock typei  Other c l a s t i c sedimentary u n i t s i n  the area ( e s p e c i a l l y the s l a t y , t u r b i d i t i c Cultus Formation) are poorly mineralized.  I t i s on t h i s basis that a mid-Cretaceous  epigenetic o r i g i n  and not a Middle J u r a s s i c syngenetic o r i g i n i s favored f o r the disseminated gold deposit i n the Ladner Gold B e l t .  A source f o r the gold i n t h i s area  can probably be r e l a t e d to deep-seated sources (sub-crustal?) which were tapped by the Hozameen Fault.  The f a c t that gold occurrences are most  prominent along the f a u l t where u l t r a m a f i c rocks occur suggests a genetic relationship. Volcanic rocks are most commonly m i n e r a l i z e d by shear, v e i n and disseminated deposits, which may also describe portions of volcanogenic deposits.  Since (a) B r i t a n n i a i s surrounded by shears which look s i m i l a r  to s u l f i d e occurrences i n the B r i t a n n i a orebodies, and (b) Seneca i s surrounded by disseminated occurrences which are s i m i l a r to portions of the Seneca deposit, a l l such occurrences are l i k e l y "volcanogenic-type" deposits. With the exception of molybdenum and n i c k e l , the predominant  metals  i n the area are copper, s i l v e r , gold, zinc and lead, i n decreasing order of abundance.  Since t h i s assemblage i s c h a r a c t e r i s t i c of v o l c a n i c rocks, i t  i s suggested that i n the study area these metals, o r i g i n a l l y  accumulated  142  i n v o l c a n i c rocks, were subsequently remobilized i n t o epigenetic deposits. Integration of t h i s information with the t e c t o n i c and metallogenic h i s t o r y of the area i n d i c a t e s that arc volcanism of the Coast P l u t o n i c Belt i s p r i m a r i l y responsible f o r the o r i g i n a l accumulations of metals. Cretaceous c o l l i s i o n with the Cascade and Intermontane B e l t s remobilized these o r i g i n a l accumulations; T e r t i a r y Cascade plutonism (and volcanism?) was also responsible f o r some r e m o b i l i z a t i o n .  During the c o l l i s i o n e p i -  sode, access to s u b - c r u s t a l sources through u l t r a m a f i c i n t r u s i o n and deepseated f a u l t i n g introduced n i c k e l and gold accumulations along the c o l l i s i o n axis.  Formation of molybdenum deposits, although d e f i n i t e l y c o r r e l a t e d  w i t h plutonism, i s not r e s t r i c t e d to any p a r t i c u l a r episode. Computer inventory f i l e s are p o t e n t i a l assets to regional studies such as t h i s one, but i t s a p p l i c a t i o n s are l i m i t e d .  As a data storage bank f o r  information necessary to acquaint one w i t h mineral deposits i n a s p e c i f i e d area, i t s p o t e n t i a l i s i n d i s p u t e d , however, i t was necessary i n t h i s study to do most t a b u l a t i o n manually.  S t a t i s t i c a l analyses of such data r e q u i r e  areas which are tailor-made to the problem under examination.  For example,  a d e t a i l e d study of a small area with a high density of occurrences i s p r a c t i c a l i f the geology i s r e l a t i v e l y uncomplicated and a p p l i c a t i o n s are on a small s c a l e .  But i f l a r g e - s c a l e problems are to be t a c k l e d , a much  larger area should be examined to eliminate s m a l l - s c a l e v a r i a t i o n s i n the large-scale picture.  The conclusions reached i n t h i s study are based on a  very small population r e l a t i v e to the l a r g e - s c a l e features discussed, and should be regarded i n t h i s l i g h t .  143 REFERENCES CITED Aho, Aaro E. (1956): Geology and genesis of u l t r a b a s i c nickel-copperp y r r h o t i t e deposits at the P a c i f i c N i c k e l Property, southwestern B r i t i s h Columbia, Economic Geology, V o l . 51, p. 444-81. 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Memoir 158, 139 p. K a y i r a , G. (1975): A mineralographic and petrographic study of the gold deposit of the Upper Idaho Zone, Hope, B r i t i s h Columbia, unpublished B.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 74 p. Leech, G. B., Lowdon, J . A., Stockwell, C. H., and Wanless, R. K. (1963): Age determinations and g e o l o g i c a l s t u d i e s , Geol. Surv. Can. Paper 63-17, p. 38-9.  145 L i t t l e , L. (1974); A mineralography study of Brandywine Property leadz i n c - g o l d - s i l v e r deposit, Brandywine map area, southwestern B r i t i s h Columbia, unpublished Geology 409 report, U n i v e r s i t y of B r i t i s h Columbia, 57 p. Lowes, B. E. (1972): Metamorphic petrology and s t r u c t u r a l geology of the area east of Harrison Lake, B r i t i s h Columbia, unpublished Ph.D. t h e s i s , U n i v e r s i t y of Washington, 161 p. Manifold, A. H. (1976): Some aspects of N o r t h a i r Mines' Brandywine property, p r e p r i n t of paper presented at the Annual Meeting of CIM D i s t r i c t 6, October 13-15, 15 p. Mathews, W. H. (1958): Geology of the Mount G a r i b a l d i map-area, southwestern B r i t i s h Columbia, Canada, Geol. Soc. Am. B u l l . , V o l . 69, p. 161-78. Mattinson, J . M. (1972): Ages of Zircons from the Northern Cascade Mountains, Washington, Geol. Soc. Am. B u l l . , V o l . 83, p. 3769-84. M c K i l l o p , G. R. (1973): Geology of southwestern Gambier I s l a n d , Howe Sound, B r i t i s h Columbia, unpublished B.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 25 p. McLeod, J . A. (1975): unpublished M.Sc.  The Giant Mascot U l t r a m a f i t e and i t s r e l a t e d ores, t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 123 p.  McLeod, J . A., V i n i n g , M., and McTaggart, K. C. (1976): Note on the age of the Giant Mascot u l t r a m a f i c body, near Hope, B r i t i s h Columbia, Can. Jour. Earth Sc., V o l . 13, p. 1152-4. McTaggart, K. C. (1971): On the o r i g i n of u l t r a m a f i c rocks, Geol. Soc. Am. B u l l . , V o l . 82, p. 23-42. McTaggart, K. C , and Thompson, R. M. (1967): Geology of part of the Northern Cascades i n southern B r i t i s h Columbia, Can. Jour. Earth Sc., Vol. 4, p. 1199-228. M i l l e r , J . H. L., S i n c l a i r , A. J . , M a n i f o l d , A. H., and W e t h e r e l l , D. (1978): Mineral deposits i n the Callaghan Creek area, southwestern B r i t i s h Columbia, p r e p r i n t of paper presented at the 80th AGM of the CIM, A p r i l 23-27, Vancouver, B. C , 7 p. Misch, P. (1966): Tectonic e v o l u t i o n of the Northern Cascades of Washington State, i n Tectonic H i s t o r y and M i n e r a l Deposits of the Western C o r d i l l e r a , CIM Spec. V o l . No. 8, p. 101-48. (1977): Bedrock geology of the North Cascades ( F i e l d Trip No. 1 ) , Geological Excursions i n the P a c i f i c Northwest, GSA Annual Meeting, S e a t t l e , WA, p. 1-24. Monger, J . W. H. (1970): Hope map area, west h a l f , B r i t i s h Columbia, Geol. Surv. Can. Paper 69-47, 75 p. , • ' ' (1977): Upper Paleozoic rocks of the Western Canadian C o r d i l l e r a and t h e i r bearing on C o r d i l l e r a n e v o l u t i o n , Can. Jour. Earth Sc., V o l . 14, p. 1832-59.  146 Monger, J . W. H., Souther, J . G., and G a b r i e l s e , H. (1972): E v o l u t i o n of the Canadian C o r d i l l e r a : A p l a t e t e c t o n i c model, Am. Jour. Sc., V o l . 272, p. 577-602. Montgomery, J . H., S i n c l a i r , A. J . , Symonds, D. F., and Giroux, G. H. (1977) : G e o s t a t i s t i c a l study of the Ladner Creek gold deposit of C a r o l i n Mines L t d . , Western Miner, V o l . 50, March, p. 11-22. N a l d r e t t , A. J . (1973): N i c k e l s u l f i d e deposits - t h e i r c l a s s i f i c a t i o n and genesis, w i t h s p e c i a l emphasis on deposits of v o l c a n i c a s s o c i a t i o n , Trans. CIMM, V o l . 76, p. 183-201. N a l d r e t t , A. J . , and Cabri, L. J . (1976): Ultramafic and r e l a t e d mafic rocks: t h e i r c l a s s i f i c a t i o n and genesis with s p e c i a l reference to the concentration of n i c k e l s u l f i d e s and platinum-group elements, Ec. Geol., Vol. 71, p. 1131-58. Orr,  J . F. W., and S i n c l a i r , A. J . (1971): A computer-processible f i l e f o r mineral deposits i n the Slocan and Slocan C i t y areas of B r i t i s h Columbia, Western Miner, V o l . 44, A p r i l , p. 22-34.  Payne, J . G., B r a t t , J . A., and Stone, B. G. (1978): Deformed Mesozoic volcanogenic copper-zinc s u l f i d e deposits i n the B r i t a n n i a D i s t r i c t , B r i t i s h Columbia, Ec. Geol., i n press. Pigage, L. C. (1976): Metamorphism of the S e t t l e r S c h i s t , southwest of Yale, B r i t i s h Columbia, Can. Jour. Earth Sc., V o l . 13, p. 405-21. P i l c h e r , S. H., and McDougall, J . J . (1976): C h a r a c t e r i s t i c s of some Canadian C o r d i l l e r a n Porphyry Prospects, i n Porphyry Deposits of the Canadian C o r d i l l e r a , CIM Spec. V o l . No. 15, p. 79-82. Read, P. B. (1960): The geology of the Fraser V a l l e y between Hope and Emory Creek, B r i t i s h Columbia, unpublished M.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 154 p. Reamsbottom, S. B. (1974): Geology and metamorphism of the Mount Breakenridge area, Harrison Lake, B r i t i s h Columbia, unpublished t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 155 p.  Ph.D.  Rice, H. M. A. (1960): Geology and mineral deposits of the P r i n c e t o n maparea, B r i t i s h Columbia, Geol. Surv. Can. Memoir 243, 136 p. Richards, T. A., and McTaggart, K. C. (1976): G r a n i t i c rocks of the southern Coast P l u t o n i c Complex and Northern Cascades of B r i t i s h Columbia, Geol. Soc. Am. B u l l . , V o l . 87, p. 935-53. Richards, T. A., and White, Wm. H. (1970): K-Ar ages of p l u t o n i c rocks between Hope, B r i t i s h Columbia, and the 49th p a r a l l e l , Can. Jour. Earth Sc., V o l . 7, p. 1203-7. Roddick, J . A. (1965): Vancouver North, Coquitlam, and P i t t Lake map-areas, B r i t i s h Columbia, with s p e c i a l emphasis on the evolution of the p l u t o n i c rocks, Geol. Surv. Can. Memoir 335, 276 p.  147 Roddick, J . A., and Hutchison, W. W. (1969): Northwestern part of Hope map area, B r i t i s h Columbia (92H/West H a l f ) , Geol. Surv. Can. Paper 69-1, pt. A., p. 29-38. ' '' (1973): Pemberton (East H a l f ) maparea, B r i t i s h Columbia, Geol. Surv. Can. Paper 73-17, 21 p. Roddick, J . A., and O k u l i t c h , A. V. (1973): Open F i l e Map No. 165, J u l y .  Fraser R i v e r , Geol. Surv. Can.  Roddick, J . A., Mathews, W. H., and Woodsworth, G. J . (1977): Southern end of the Coast P l u t o n i c Complex, Geol. Assoc. Can. Annual Meeting, Vancouver, B r i t i s h Columbia, F i e l d Trip No. 9, 33 p. S c h o f i e l d , S. J . (1918): B r i t a n n i a map area, B r i t i s h Columbia, Geol. Surv. Can. Summary Report, p. 56B-59B. (1922): Ore deposits of B r i t i s h Columbia, i n Geology and ore deposits of Salmon River D i s t r i c t , B r i t i s h Columbia, Geol. Surv. Can. Memoir 132, p. 63-73. (1926): V o l . 21, p. 271-84.  The B r i t a n n i a Mines, B r i t i s h Columbia, Ec. Geol.,  S i n c l a i r , A. J . , Wynne-Edwards, H. R., and Sutherland Brown, A. (1978): An a n a l y s i s of d i s t r i b u t i o n of mineral occurrences i n B r i t i s h Columbia, B. C. Dept. Mines and Pet. Res. B u l l . , i n press. Staatz, M. H., Tabor, R. W., Weis, P. L., Robertson, J . F., Van Noy, R. M., and Pattee, E. C. (1972): Geology and mineral resources of the northern part of the North Cascades National Park, Washington, U. S. Geol. Surv. B u l l . 1359, 132 p. Staatz, M. H., Weis, P. L., Tabor, R. W., Robertson, J . F., Van Noy, R. M., Pattee, E. C., and H o l t , D. C. (1971): Mineral resources of the Pasayten Wilderness Area, Washington, U. S. Geol. Surv. B u l l . 1325, 255 p. Sutherland Brown, A., and Cathro, R. J . (1976): A perspective of porphyry deposits, i n Porphyry deposits of the Canadian C o r d i l l e r a , CIMM Spec. V o l . 15, p. 7-16. Sutherland Brown, A., and Robinson, J . W. (1970): B r i t a n n i a Mine, B. C. Dept. of Mines and Pet. Res., G. E. M., p. 233-45. Sutherland Brown, A., Cathro, R. J . , Pantaleyev, A., and Ney, C. S. (1971): Metallogeny of the Canadian C o r d i l l e r a , CIM B u l l . , V o l . 64, No. ;709,. p. 37-61. Tabor, R. W. , Engels, J . C , and Staatz, M. H. (1968): Quartz d i o r i t e quartz monzonite and g r a n i t i c plutons of the Pasayten River area, Washington - petrology, age and emplacement, U. S. Geol. Surv. Prof. Paper 600-C, p. C45-52.  148 Turekian, K, K. , and Wedepohl, K. H. ( 1 9 6 1 ) : D i s t r i b u t i o n of the elements i n some major u n i t s of the earth's c r u s t , Geol, Soc. Am. B u l l . , V o l . 72, p. 175-92. Van Eysinga, F. W. B. (1975):  Geological Time Table, 3rd e d i t i o n .  V i n i n g , M. R. (1977): The Spuzzum pluton northwest of Hope, B r i t i s h Columbia, unpublished M.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 147 p. Wanless, R. K., Stevens, R. D., Lachance, G. R., and Delabio, R. N. (1973): Age determinations and g e o l o g i c a l studies, K-Ar i s o t o p i c ages, Report No. 11, Geol. Surv. Can. Paper 73-2, p. 9-13. (1977): Age determinations and g e o l o g i c a l studies, K-Ar i s o t o p i c ages, Report No. 13, Geol. Surv. Can. Paper 77-2, p. 11-14. Wanless, R. K., Stevens, R. D., Lachance, G. R., and Edmonds, C. M. (1967): Age determinations and g e o l o g i c a l s t u d i e s , K-Ar i s o t o p i c ages, Report No. 7, Geol. Surv. Can. Paper 66-17, p. 11-14. White, Wm. H. (1968): G r a n i t i c rocks of southwestern B r i t i s h Columbia, i n Guidebook f o r Geological F i e l d Trips i n Southwestern B r i t i s h Columbia, U.B.C. Geology Dept. Rept. No. 6, W. H. Mathews, ed., A p r i l , p. 13-17. Woodsworth, G. J . (1977): F i l e Map No. 482.  Pemberton (92J) map-area, Geol. Surv. Can. Open  Woodsworth, G. J . , Pearson, D. E., and S i n c l a i r , A. J . (1977): Metal d i s t r i b u t i o n patterns across the eastern f l a n k of the Coast P l u t o n i c Complex, south-central B r i t i s h Columbia, Ec. Geol., V o l . 72, p. 170-83.  APPENDIX A  STATISTICAL DATA BASE  TABLE A-l. DISTRIBUTION.OF C O M M O D I T Y OCCURRENCES.INTO. DEPOSIT.TYPES  rH  1  veins  shears  1  1 1  1  1  (1) disseminated  massive  magmatic  skarns  porphyries  volcanogenic  1 1  20  17 .  12  13  C2)  31  20  13  1  14  26  l  CD  10 C2)  CD  l  10 2  13  1  1  1  c  CD  C2)  5  15  1 10  37  33  14  1  C2)  5  15  9  C3)  C2) (2) 2 C2) 1  9  C9) 7  9  1  CD  C4) CD  2 2 C2) C2) 2  5  CD  64  1  20 11  1  C2)  2  CD C18)  2  2  2  . 1  2  4  10 (2)  •  1  44  C16)  CD  CD  3  1  -O  CD  CD  CD  CD  2  CD  Cl)  CD unknown  45  C13) C9) CD  rH  CD 7  (D  5  1  CD  11  CD  2 2 C2) C2) 8  5  "The lower number in parentheses is the number of commodity occurrences from deposits with production records; this number is included in the total count above it.  N U M B E R OF C O M M O D I T Y OCCURRENCES AND DEPOSIT TYPES IN EACH TECTONIC BELT OR BELT SUBDIVISION IN THE STUDY AREA'  4J  o Coast Plutonic Belt Intrusions 10,187 Km  2  Coast Plutonic Belt Pendants . 2,652 Km  10 (3)  y  1  Spuzzum Plutonic Belt Pendants 1,145 Km  1  2  Hozameen Basin 1,111 KE2 Ladner Trough 1,875 Km2 Eagle Plutonic Belt 1,787 Km 2  Total.. 23,473 Km  u  U  a u  C  1  Spuzzum Plutonic Belt Intrusions3,097 Km  Cascade Belt 1,619 Km  rH 01  c N  5 (1)  59 (9)  32 (7)  10 (1)  11 (1)  1  1  4 (1)  2  3  3  1 (1)  1  1  1  2  0)  32 (3)  3 (1)  20 (5)  e oi  | Xi  CO  rt1  a E  01 ;> rH  cn  u  §  CO  u  e  cd  u  19 (1)  9 (3)  (D  4  30 (9)  CD  2  1  1  1  OO  CO rt|  rH  WO  7 (2)  1  25 (9)  15 (6)  1  C3)  1  3  1  1  3  | rt 3  •H  s i  1  4 (1)  15 (3)  6  16 (1)  10 (1)  1  21 (7)  17 (5)  1  18  6  19 176 77 (1) (25) (14)  6  (D  3 (1)  3  u  o a  8  1  15 (1)  3  2 (1)  22 (9)  2  5  9  1  1  7  (D  1  9  17 (1)  c  rtO r*l CO  E  -H  > • *  >  21 (1)  u  9 (2)  1  2 (2)  8 8  1  4  13 (5)  14 (2)  (D  2  1  1  4  7  1  8  2  (D  CH)  37  15 (6)  10  6  6 111 53 (3) (24) (14)  1 (1)  2  1 (1)  1  4  1  7 (2) 4  1  7  (D  1  5  2  14 (1)  41 (2)  23 (4)  1  5  7  7  2 80 (2) (19)  19  >  CO CO  « E  24 (2)  rt  rH  u  o  H  35 (2) 1  65 (12) 14  (D 6  (D  3  7  (D 34 (10)  (D  CJ CO CO •H T)  1  CD CD  E  rt 01 .£ CO  •H  (D  2  3 (1)  14 (3)  41 104 (4) (26)  j=  7  CD CD  .&  .ated  u  togenic  TABLE A-2.  23 (3) 4  23  (D  2  45 (11)  2  17  39 (1)  5  228 (31)  'The lower number in parentheses is the number of deposits with production records; this number is included in the total count above it. ' Areal calculations are included below each division name. \  TABLE A-3.  DENSITIES (NUMBER OF DEPOSITS/100 III ) OF COMMODITY OCCURRENCES AND DEPOSIT TYPES IN EACH TECTONIC BELT OR BELT SUBDIVISION IN THE STUDY AREA' 2  o  1  w  Coast Plutonic Bait Intrusions  .05  Coast Plutonic B e l t Pendants  .98 (.29)  *H 41 O  a .03  u  « •fc  u  *  8  a  jj N  .81 (.08)  .13 (.03)  .48 (.03)  .23 (.08)  5.76 (.88)  3.13 (.68)  .39 (.10)  2.93  .08  .17  a  .08  .84 (.08)  .92 (.08)  Spuzzum Plutonic B e l t Pendants  .23  .23  .90 (.23)  .48 (.16)  .32  2.40 (.48)  .96  .70  .70  3.73 (.23)  2.33 (.23)  .23  .14 (.14)  • 14  2.90 (.97)  2.35 (.69)  .14  .14  14  Hozameen Basin -  Ladner Trough  Eagle Plutonic B e l t  Total  .22 (.06)  .02  .21 (.01)  V  a u  Spuzzum Plutonic Belt Intrusions  Cascade Belt  §  u ti  2.61  1.94 (.28)  .23  .87  .85 (.15)  .03 (.01)  §• -J  41  S  .& J §  S w  JI V  3  3 8>  §  &  4J  •  .18 (.05)  .03  • §  •Sa 9  O  fr  1s  o a  .03  C.B8)  .10 (.10)  .29 (.29)  2.44 (.88)  1,46 (.59)  .10  .08  .08  .08  .25  .08  .08  &  .67 (.08)  .96 (.16)  2.24 (.48)  .70  3.50 (.23)  .70  .28 3.04 (.14) (1.24)  .28  .72  1.30  .14  .45 (.04)  1.15 (.29)  .01  ..08 (.01)  3 m  i  .88 (.20)  .20  .17  .68 (.23)  .90 (.23)  E  a u  .33 (.03) .68  «  !  ti  j: m  S  i  .21 (.03)  .03  .10  1.27 (.49)  1.37 (.20)  1.86 (.10)  .17  .08  .08  1.17 (.08)  .23  1.36 (.23)  .48  3.68 (.48)  p G M o  •  ti  >  .23  .90 (.23)  .16  1.44  1.12 (.16)  .16  .64  1.12 (.32)  1.12 (.16)  .23  3.96 (.23)  1.86 (.23)  .47  .23  .93  1.17 (.23)  5.11 (1.52)  2.07 (.83)  .14  .14 (.14)  1.45  .87  .14  .72  .29  1.22 (.26)  .58 (.15)  .15 (.01)  .45 (.02)  .25 (.04)  .07 (.03)  'ho lower number i n parentheses i s the number o f deposits with production  .14 (.14)  .02  .01 (.01)  4.70 (1.38)  «  .16  1.63  .97  1.01  .02 (.02)  .88 (.21)  w  .26 (.02)  t> n  1 .89 (.05)  .10  .93  6.35 (1.17)  5.36 (.23)  .28  6.23 (1.52)  .29  2.46  .43 (.01)  records; t h i s number i s included i n the t o t a l count above i t .  .06  2.52 (.34)  .23  Coast Plutonic Belt Pendants  4.45 (1.32)  .14  1.10  Spuzzum Plutonic Belt Pendants  u  4.00 (.38) 1.10  M  2, .97 .45)  3.68 C.80)  .87 (.22)  2.55 (.77)  .47  .09  .38  .07  ('.04)  7. .67 (7 .67)  .46  (...12) 1 .24 .25)  1.13  Rozaejeen Basin  3.18  3.33  1 .92 .12)  2.74 .27  ".adner Trough  .64 (.64)  .67  1 .49  2.76 (.81)  .64  .67  1 .35  1.02  1.00 (.05)  .1 .00 .14)  ^ho  1.00  (..50)  (  1.00 (.18)  *  a  4.14 1.25 C1.25) (.4.14) 1.00  1.56  3.04 (.20)  8.75  4 .67  .62 (.31)  2.64 (1.08)  3.50  1.60  1.13  1.00 (.09)  l.oo (.25)  Si  1  -  3  . 15 (.04)  .05  .20  2.00 (.72)  2.52 0.02)  5.00  .14  4.00  .20  fr  JS  & o  1.00  l.OO  (.13)  .92  1.18  1.93 (.28)  1.07  1.42  3.29  3.25 (.19)  3.21 (.40)  3.13  .51  14.00 (14.00)  4.19 3.57 (1.25) (1.43)  1.00 (.50)  3.52 10.00 (.80)(10.00)  .38  2.29  14.00  s  1.18 (.07) 1.51  4.47 (.53)  e  2  1.19  1.50  1.00 (.21)  1.00 (.26)  .93  .93  1.00  1.00 • (1.00)  1.00 (.07)  1.00 (.04)  • -o  .24 (.03)  .12  .23  1.44 (..56)  5.27 (.77)  4.33 (.23)  .19  .31  .19  .46 (.03)  .53  .54 (.09)  1.12  1.46 (.19)  4.48 (1.28)  1.27 (.18)  3.72  1.33 (.26)  .62  3.79  5.34 (1.57) 1.16  1.00 (.16)  1.15  1.00 (1.00)  •3  .c 3 n  1  1.02 (.26)  .31 (.31) ' 1.60  h  a  isive  I  iseminated  •rt  •o  Leanogenlc  1 |  •o  .56 (.19)  7, .67  .00  1.14  .78 (.20) 1.95 (.42)  ( .33)  a u & g  Lsmuth  i  2.13 (.35)  (. (,  1  ltlmony  .20 C.07)  .15 (.03)  1.52  1.00 (-27)  a  .42  2.18 (.73)  Total  a  I,.04)  Cascade Belt  Eagle Plutonic Belt  «  1.07 (.07)  (.  •07.  Spuzzum Plutonic Belt. Intrusions  a  c  Liver  CoaBt Plutonic Belt Intrusions  u  O.  rlybdenum  -  b V o.  rsehlc  a p  RELATIVE DENSITIES OF COMMODITY OCCURRENCES AND DEPOSIT TYPES IN EACH TECTONIC BELT OR BELT SUBDIVISION IN THE STUDY AREA* >balt .  TABLE A-4.  1.00 (.24)  3.73  •  1.00 (.08)  i  •2 .35 (.02)  1.67  15.50  2.52 (.46)  2.13 (.09)  .65  2.47 (.60)  .67  .98  1.00 (.02)  lower number i n parentheses i s the number of deposits with production records; t h i s number i s included i n the t o t a l count above i t .  1.00  1.00 (.13)  o  I u o  u Coast Plutonic Complex  Chilliwack and Ht. Barr Batholltha  M  t  2 1  u -  Ti  I  l  34  1  V  7 (2)  3  1  19 %  4  Invermay Stock  2 (1)  2 (1)  Scuzzy/Spuzzum Plutons  3 (1)  1  8  3  Eagle Cooplex  l  Clant Mascot Ultramafite  O)  S"  >  0  3  *  •t  u  12  1 (1)  Cheakamus Formation  (11).  1 (1)  2  ft  1  •o  a  a  3  e«  S S «•  •fl  3  1  M  •  M «  3  (1)  1  1 2 (1)  2  l  4  3  7  *'  1  1  1  i (i)  (O  -  3  3  1  2 4  3  ftl  (4)  (i)  2 (1)  2 (1)  I  3 (1)  (1) i  1  -  8  2  1 (O  1 1  3  1  4 (1)  1 (1)  1 1  1 -  2  1  3  5  9  1  (2)  (2)  1  1  1  2  1  l  2  1  (1)  <>  1  1 (1)  (1)  2  1  (I)  1  3  3  -  1  f  *  .1  1  1 (1)  21  13 (2)  1  10  (2)  Cambler T Group  2 (1)  9 (4)  (3)  6  1 (1)  O)  Harrison Lake Formation  1  12  9  1  (1)  (1)  5 (2)  Hozameen Group  2  16  10 (1>  1  2  14  (3)  12 (5)  10 (3)  1  6  3  2 (1)  2  O)  (1)  1  1  1  5  i (i)  3  16 (7V 5 1  1  7  4 (1)  2 (2)  5 (3) • (3) (2)  3 (0  2 1  1  18 (3)  7 (1)  21 (8)  11 (4)  8  4  1 (0  1 (1)  1  1  I  6 (2)  6 (2)  ft  ft  (3)  1 (0  5 (2) (2)  (2)  H  3  i  1  6 (2)  3o  11 (2)  1  1  -  21 (1)  2 (1) 1  0 00 g u  (l)  T  1 (1)  4 (1)  1 (1)  S r i "  -  Gambler Group  2  ft  fr  11 (3)  1  F i r e Lake Group  Twin Islands Group  '2  (2)  3  2 (1)  8  Echo Island Formation  Skagit Formation  I  | s  I  1  * 1 (1)  Custer Gneiss  Pasayten Group  E 2  l  <4>  3  (i)  Cultus Formation  Nicola Group  9  a  1 (1)  (2)  Chuckanut Formation  Ladner Croup  c  2 (O  1  A g a s s l i P r a i r i e Formation  Chilliwack Group  V  u  >>  1  Needle Peak Pluton  Boven Island Croup  I  1  N  (4)  o  2  S (1)  2  . 2  .Ul  2  1 i  i  to  1  (1)  ft  .U) 1  :  3  2 (1)  1 (1)  3 (»  10 (4)  2 (1)  1  V "  14 (2)  .9  1  6  21 (7)  3  2  (3)  • :  21 (2)  7  1 (1)  J  24 (3) 27 (8) 8  ' 8 1  i  1  2 (1)  i  1  <D  1  The lower number i n parentheses i s the number o f d e p o s i t s with production r e c o r d s ; . t h i s number i s i n c l u d e d ' i n the t o t a l countabove i t . .. .  1  6 (2)  pyroclastic volcanic rocks  2 (1)  9 (1)  13 (4)  unclassified volcanic rocks  13  4  1  6  dikes  9 (2)  4 (1)  2  8 (2)  A6  14 (2)  28 (1)  22 (4)  15 (2)  1  21 (7)  10 (4)  1  2  24 (9)  22 (4)  11 (1)  1  4 (1)  19 (4)  10 (2)  8 (1)  2  6 (2)  6  2  1  2  1  26 (1)  14 (1)  5  15 (2)  22 (3)  intermediate to acid intrusive rocks  2  1  ultramafic rocks  1  1  clastic sedimentary rocks  2 (1)  limes tone  8 (2)  unclassified sedimentary rocks  3 (1)  W  15 (1)  2  schist  unknown  2  2  2  1 (1)  1  9 (2)  15 (1)  2  1  2 (2)  2  8 (5)  6 (4)  1  7  4  3  2 (2)  7 (2)  2 (1)  4  2  19 (3)  11 (1)  28 (1)  1  2  1  1 (1)  7  6  5  2  1  4 (1)  1 (1)  3  2  16 (3)  2  9  2 tl)  3  1  1 (1)  2  28 (9)  1  6  6  1  19 (3)  3  1 (1)  1  4 (1)  1  2  1 (1)  3 (1)  5  2  1  1  3  5  12 (3)  2  1  29 (9)  10 (6)  14 (2) 6 (2)  9 (1)  1 (1)  3  5  6 (4)  14 (1)  6 (1)  2  15 (4)  1  4 (1)  1  1 (1)  5 (2)  3  1  2 (1)  4 (2)  1  8 (5)  1  massive  2  disseminated  10 (2)  shear  12 (2)  vein  3 (1)  volcanogenic  acid volcanic rocks  1  skarn  20 (7)  porphyry  lead  3  cobalt  24 (4)  iron  38 (8)  magmatic  gold  14 (4)  6 (3)  uranium  tungsten  21 (7)  basic volcanic rocks; greenstone  bismuth  antimony  .cadmium  silver  ; molybdenum  2 (2)  zinc  4 (1)  ;copper  arsenic  NUMBER OF COMMODITY OCCURRENCES"AND DEPOSIT TYPES - IN HOST ROCK TYPES IN THE STUDY AREA'  nickel  TABLE A-6.  2  The lower number in parentheses is the number of deposits with production records; this number is included in the total count above it.  APPENDIX B  DEPOSIT DISTRIBUTION MAPS  157  TABLE B - l .  SYMBOL DEFINITIONS FOR DEPOSIT DISTRIBUTION MAPS  Unless s p e c i f i e d on the map, symbols used to designate deposit l o c a t i o n s are defined by deposit type as f o l l o w s : Vein Skarn  CD  Disseminated Shear Magmatic Volcanogenic  o x  Porphyry Massive Unknown Symbol s i z e on a l l maps i s determined as follows: Magnitude (Table 4-2)  Note: ^  Size  I  o  II  E  III  •  IV  •  A l l maps i n t h i s appendix are Xerox reductions of o r i g i n a l Calcomp p l o t t e r output; r e s u l t i n g d i s t o r t i o n may have a l t e r e d the accuracy of deposit l o c a t i o n s .  MAP  B-2.  D i s t r i b u t i o n of Shear Deposits  X  I—»  o  MAP B-3.  D i s t r i b u t i o n of Disseminated Deposits  MAP  B-4.  D i s t r i b u t i o n of Massive Deposits  X  MAP  B-5.  D i s t r i b u t i o n , of Magmatic Deposits  MAP B-7.  D i s t r i b u t i o n of Porphyry Deposits  MAP B-8.  D i s t r i b u t i o n of Volcanogenic Deposits  X SI 1st rank LD 2nd rank  MAP B-10.  D i s t r i b u t i o n of Copper Occurrences (according to f i r s t , second or lower rank)  jgg 1st rank  .  0  2nd rank  X  3rd or lower rank  Distribution of Gold Occurrences (according to f i r s t , second or lower rank)  MAP B-13.  D i s t r i b u t i o n of a l l S i l v e r Occurrences (regardless of rank)  MAP B-14.  g§  1st rank  •  2nd rank  X  3rd or lower rank  D i s t r i b u t i o n of S i l v e r Occurrences (according to f i r s t , second or lower rank)  X  •^1  MAP B-15.  D i s t r i b u t i o n of a l l Zinc Occurrences (regardless of rank)  gjg 1st rank  MAP B-16.  Q  2nd rank  X  3rd or lower rank  D i s t r i b u t i o n of Zinc Occurrences (according to f i r s t , second or lower rank)  X  MAP B-17.  D i s t r i b u t i o n of a l l Lead Occurrences (regardless of rank)  MAP  B-18.  H  1st rank  •  2nd  X  3rd o r l o w e r  rank  D i s t r i b u t i o n o f Lead O c c u r r e n c e s ( a c c o r d i n g to f i r s t , second o r lower rank)  rank  X  MAP B-19.  D i s t r i b u t i o n of a l l Molybdenum Occurrences (regardless of rank)  )  X  HI  1st rank  Q X  2nd rank 3 r d or lower rank  92/GO MOLY MAP B-20.  D i s t r i b u t i o n o f Molybdenum Occurrences ( a c c o r d i n g to f i r s t ,  second o r lower rank)  MAP B-21.  D i s t r i b u t i o n of a l l Iron Occurrences (regardless of rank)  'MAP  B-22.  D i s t r i b u t i o n of Iron Occurrences (according to f i r s t , second, t h i r d or lower rank)  /  MAP  B-24.  D i s t r i b u t i o n o f a l l Tungsten Occurrences ( r e g a r d l e s s o f rank)  X  oo  MAP B-25.  D i s t r i b u t i o n of a l l Antimony Occurrences (regardless of rank)  •  Au + Ag  X  Au without Ag  - j - Ag without Au  92/GO  1L  GOLD/SILVER  MAP B-26.  D i s t r i b u t i o n Relationships Between Gold and S i l v e r Occurrences  X  \J] X  92/GD MOLY/COPPER MAP B-27.  D i s t r i b u t i o n Relationships.Between Molybdenum and Copper Oc  currences  Mo + Cu M  o  without Cu  •  Mo + Au + Ag  -f~  Mo + Ag only  X  Mo + Au only  92/GD MOLY/GOLD/SILVER MAP B-28. D i s t r i b u t i o n Relationships Between Molybdenum, Gold and S i l v e r Occurren  ces  •  .  D i s t r i b u t i o n Relationships Between Lead and S i l v e r Occurrences  Pb + Ag  X  CO X  Pb + P  b  Zn  without  Zn  00  MAP  B-30.  D i s t r i b u t i o n R e l a t i o n s h i p s Between Lead and Z i n c Occurrences  

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