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Sedimentology and petrology of the cedar district formation : late cretaceous, southwestern British Columbia. Rahmani, Riyadh Abdul-Rahim 1968

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SEDIMENTOLOGY AND PETROLOGY OF THE CEDAR DISTRICT FORMATION, LATE CRETACEOUS, SOUTHWESTERN B R I T I S H COLUMBIA by RIYADH ABDUL-RAHIM RAHMANI B.Sc.j  U n i v e r s i t y o f Baghdad,  1965  A THESIS SUBMITTED I N P A R T I A L FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department o f Geology  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e required  standard  THE UNIVERSITY OF B R I T I S H COLUMBIA JULY,  1968  In presenting this thesis in p a r t i a l  f u l f i l m e n t of the requirements  for an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the Library s h a l l make it f r e e l y a v a i l a b l e for reference and Study.  I further agree that permission for extensive copying of  this  thesis for s c h o l a r l y purposes may be granted by the Head of my Department or by hils representatives.  It  is understood that copying  or p u b l i c a t i o n of this thesis for f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission.  Department of The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada  (i)  ABSTRACT The mation  Upper C r e t a c e o u s  o f t h e G u l f I s l a n d s and  o f s h a l e and  sandstone,  quences of s h a l e , which and  (Campanian) Cedar D i s t r i c t  which may  the f l y s c h - t y p e .  Presence  c o n v o l u t e l a m i n a t i o n s , and  a d j a c e n t a r e a s i s composed a r e p r e s e n t as t h i c k  o r may  as a l t e r n a t i n g r h y t h m i c  n o t be  of graded  sequences of  bedding,  ripple  s o l e marks i n t h e l a t t e r The  d i v i s i o n s o f Bouma (1962) and  sug-  l a r g e l y to  other authors,  indicate that t h e i r d e p o s i t i o n took place l a r g e l y  Convolute  and  internal structures  of the i n d i v i d u a l t u r b i d i t e u n i t s correspond  the lower f l o w  se-  fossiliferous,  sandstone-shale  gest a t u r b i d i t y current o r i g i n .  t h e C-E  For-  and  within  regime. l a m i n a t i o n i n the sandstones  o v e r s t e e p e n i n g and  deformation  was  of p r e - e x i s t i n g  l a m i n a t i o n and b y t h e d e f o r m a t i o n  formed  by  ripple  of p r e - e x i s t i n g  plane-  p a r a l l e l l a m i n a t i o n by t h e d r a g o f the o v e r p a s s i n g c u r rents.  F l u t e and  o n l y found  g r o o v e c a s t s and  f r o n d e s c e n t marks were  i n b e d s t h i c k e r t h a n a f o o t and  Calcareous  a  half.  c o n c r e t i o n s , most a b u n d a n t i n t h e  shales  and  o c c a s i o n a l l y p h o s p h a t i c , a r e c r o s s e d by o r g a n i c  and  burrows which  rounding beds.  are f i l l e d with  1  sediments  borings  of the sur-  Host r o c k s of the c a l c a r e o u s c o n c r e t i o n s  t e n d t o t h i c k e n a r o u n d them.  The  c o n c r e t i o n s show  (ii)  d e f o r m a t i o n when p r e s e n t i n b e d s i n v o l v e d i n s o f t - s e d i ment d e f o r m a t i o n .  A l l these observations suggest  their  f o r m a t i o n i n t h e e a r l y stage of d i a g e n e s i s , probably s h o r t l y after, b u r i a l . Sandstones o f t h e Cedar D i s t r i c t Formation  show a  g r a d a t i o n f r o m a r e n i t e s t h a t l a c k m a t r i x and have a c a l cite  cement, t o wackes r i c h  i n fine-grained matrix.  The  m a j o r i t y o f t h e wackes and t h e a r e n i t e s a r e f e l d s p a t h i c and  arkosic, using the c l a s s i f i c a t i o n of G i l b e r t  (1954).  T h e i r c o m p o s i t i o n i n d i c a t e s t h a t tfye. m a j o r s o u r c e a c i d i c t o i n t e r m e d i a t e igneous metamorphic rock , a secondary  sedimentary  source.  a n d / o r l o w t o medium g r a d e and v o l c a n i c r o c k s were  The m a j o r s o u r c e a r e a was  possibly  a r e g i o n o f h i g h r e l i e f t h a t had undergone r a p i d and  erosion-, and e x p e r i e n c e d m a i n l y m e c h a n i c a l  P a l e o c . u r r e h t s . and l i t h o l o g i c t h a t the major source  1  was  lateral variation  area f o r the coarse  uplift  "weathering. indicate  elastics  was  s i t u a t e d t o t h e e a s t a n d ' s o u t h e a s t o f t h e s t u d y a r e a v The pre-Jurassic  l o w g r a d e m e t a m o r p h i c . r o c k s o f - the. C a s c a d e  M o u n t a i n s , to., t h e east.-, a n d t h e p r e - C a r b o n i f e r o u s - c r y s t a l line  r o c k s of. t h e S a n J u a n I s l a n d s , to. t h e s o u t h e a s t  s e r v e d as p o s s i b l e source areas, f o r t h e coarse  elastics'.  D e p o s i t i o n o f s h a l e y , f o s s i l i f erous parts, o f t h e f o r m a t i o n i n t h e s o u t h e a s t e r n p a r t , of- t h e s t u d y  area,  (iii)  took place  in littoral  t o upper n e r i t i c  ( f l y s c h - t y p e ) sequences were d e p o s i t e d b e l o w t h e wave b a s e . c e n t r a l and  northern  The  depths. T u r b i d i t e i n deeper w a t e r ,  u n f o s s i l i f e r o u s shale of  p a r t s of the study  t e d e i t h e r a t about the  a r e a was  deposi-  same d e p t h s a s t h e t u r b i d i t e s ,  i n deeper water, s i n c e t h i n , d e l i c a t e , h o r i z o n t a l cross l a m i n a t i o n s are preserved logic  the  i n these  rocks.  and-  Paleonto-  evidence suggests that d e p o s i t i o n took place  somewhat r e s t r i c t e d b a s i n h a v i n g  a narrow  c e n t r a l and  suggest t h a t the bottom c o n d i t i o n s of  minerathe  northern p a r t s of the b a s i n of d e p o s i t i o n  were s t a g n a n t  and  reducing.  Fac'ies r e l a t i o n s h i p s s u g g e s t t h a t t h e b a s i n d e p o s i t i o n had  of  i t s l o n g e s t d i m e n s i o n t r e n d i n g SE-NW. I t s  eastern, southeastern,  and  southern  ated between the mainland of B r i t i s h and  in a  connection  w i t h t h e o p e n o c e a n t o t h e w e s t . P a l e o n t o l o g i c and l o g i c data  or  the Gulf-San  Juan I s l a n d s .  b o u n d a r i e s were  situ-  Columbia-Washington  I t s northern  and  north-  w e s t e r n b o u n d a r i e s were p o s s i b l y n e a r the  c i t y o f Nanaimo  and  connected  Gabriola Island.  To  l e a s t p a r t i a l l y to the p a r t of the  floor,  In the  sequences which are  suggests f l u c t u a t i o n s i n the  e i t h e r due  movements.  open ocean.  t o changes i n sea  at  southeastern  study area, a l t e r n a t i o n of t h i c k ,  s h a l e s e q u e n c e s , and turbidites  t h e w e s t , i t was  fossiliferous  predominantly depth of the  basin  l e v e l or to t e c t o n i c  (v) Page 6.  SEDIMENTARY STRUCTURES A. I n t e r n a l S t r u c t u r e s w i t h i n Turbidite Units a. G r a d e d D i v i s i o n ( A - d i v i s i o n ) b. L o w e r D i v i s i o n o f P l a n e - P a r a l l e l Lamination (B-division) c. D i v i s i o n o f R i p p l e and C o n v o l u t e Lamination (C-division) d. I n t e r t u r b i d i t e D i v i s i o n (DE-division) B. S o l e M a r k s a. F l u t e C a s t s b. F r o n d e s c e n t M a r k s c. G r o o v e C a s t s d. Bounce C a s t s e. O r g a n i c B o r i n g s a n d B u r r o w s C. S o f t - S e d i m e n t D i s t u r b e d B e d d i n g D. . S a n d s t o n e D i k e s a n d M i s c e l l a n e o u s Features  62 63 64 67 6$ 73 75 77 7# S O S3 $4 84 90  7.  PETROGRAPHY OF THE SANDSTONE A. Q u a r t z B. F e l d s p a r C ,. Rock F r a g m e n t s D. M i c a E. C h l o r i t e F. P o l y c r y s t a l l i n e Q u a r t z G. C h e r t H. O t h e r M i n e r a l s I . Unknown M i n e r a l s J . Cement K. M a t r i x L. S a n d s t o n e C l a s s i f i c a t i o n  96 96 9# 99 100 100 101 101 101 103 103 104 106  8.  GRAIN S I Z E DISTRIBUTION  108  9.  DIRECTIONAL STRUCTURES AND PALEOCURRENTS A. M e t h o d s B. P r e s e n t a t i o n and I n t e r p r e t a t i o n of Data  10.  PALEOGEOGRAPHY A. B a s i n G e o m e t r y B. D i s p e r s a l C. P r o v e n a n c e D. E n v i r o n m e n t o f D e p o s i t i o n  110 110 111 114 114 117 119 121  (vi)  Page  11.  SUMMARY AND  12.  BIBLIOGRAPHY  13.  APPENDIX;  CONCLUSIONS-  124 128 135  (vii)  ILLUSTRATIONS Figures  Page  1  I n d e x Map  2  2  S t r u c t u r e and d i s t r i b u t i o n  of the  Nanaimo  Group i n t h e  Gulf  3  Intersecting  joints  i n sandstone  10  4  Intersecting  joints  i n shale  10  5  V a r i a t i o n i n spacing  6 7  T u r b i d i t e u n i t and i t s d i v i s i o n s Columnar s e c t i o n s o f the Cedar D i s t r i c t Formation  19  8  P e b b l y mudstone o f S a t u r n a I s l a n d  31  9  Conglomerate  10  I s l a n d s and V i c i n i t y  of  joints  5 '  10 15  3 1  of Saturna Island  Contact of the Cedar D i s t r i c t Formation and t h e P r o t e c t i o n F o r m a t i o n , V e s u v i u s Bay, Salt S p r i n g I s l a n d  31  Sandstone beds a t the base o f DeCourcy Formation, Vesuvius Bay, S a l t Spring Island  33  C o n t a c t b e t w e e n t h e D e C o u r c y F o r m a t i o n and the u n d e r l y i n g Cedar D i s t r i c t F o r m a t i o n , Dodd N a r r o w s , V a n c o u v e r I s l a n d  33  Concentric concretionary weathering i n the shale of the Cedar D i s t r i c t F o r m a t i o n , B e d w e l l Harbour, N o r t h Pender I s l a n d  33  14  Sandstone d i k e c u t t i n g  33  15  T y p i c a l t u r b i d i t e sequence o f s h a l e and s a n d s t o n e b e d s  11 12  13  16  s h a l e sequence interbedded  Logarithmic p r o b a b i l i t y plots of thicknesses o f B , C , a n d DE d i v i s i o n s , V e s u v i u s B a y , Salt Spring Island.  33  36  (viii)  Figures 17  18  - Page Logarithmic  'Probability  plots  of  thicknesses  o f B , C, and DE d i v i s i o n s , V e s u v i u s Salt Spring Island  Bay,  37  Lograithmic p r o b a b i l i t y plots of thicknesses o f B - , C, and DE d i v i s i o n s , B e d w e l l H a r b o u r s e c t i o n , North Pender I s l a n d .  38  K a o l i n i t e / I l l i t e r a t i o c o n t o u r map o f t h e s h a l e of t h e Cedar D i s t r i c t Formation  41  20  S h a l e y p a r t o f t h e V e s u v i u s Bay  43  21  Turbidite tage  22  A l t e r n a t i n g sandstone beds w i t h t h i c k e r s h a l e b e d s . Low s a n d s t o n e p e r c e n t a g e  43  T h i c k m a s s i v e s a n d s t o n e bed w i t h d i k e i n j e c t e d from below  43  19  23 24 25  section  sequence o f h i g h sandstone  • T u r b i d i t e sequence showing . f o r m i t y i n bed t h i c k n e s s T u r b i d i t e bed divisions  showing  percen-  sandstone  lateral uni43  r e p e t i t i o n of i t s 43  26  T h i c k bed o f s a n d s t o n e e n c l o s e s a d e f o r m e d t h i n l y bedded sandstone c l a s t ( d e r i v e d from the u n d e r l y i n g beds?)  27  T h i c k bed o f s a n d s t o n e e n c l o s e s a laminated c l a s t of sandstone  28  Pebbles from the Saturna I s l a n d mudstone  29  Specimen from t h e upper  30 31  43  thinly  pebbly  50 50  p a r t of the  S a t u r n a I s l a n d p e b b l y mudstone  50  N o r t h P e n d e r • I s l a n d b r e c c i a bed Specimen from the N o r t h Fender I s l a n d b r e c c i a  50 50  (ix)  Figures  Page  32  Calcareous stone bed  33  C a l c a r e o u s c o n c r e t i o n embedded  34  C a l c a r e o u s c o n c r e t i o n c r o s s e d by g r a i n e d t h i n sandstone bed  35  Calcareous nuous b e d  36  Calcareous concretions with i t s longest dimension c u t t i n g shale lamination  53  37  Calcareous concretion enclosing a bivalved shell  53  38  Photomicrograph of a calcareous concretion showing m i c r o f o s s i l s f i l l e d w i t h c a l c i t e and p y r i t e  55  39  Photomicrograph of a calcareous showing d e t r i t a l g r a i n s  55  40  Photomicrograph of a calcareous concretion showing p l a n k t o n i c f o r a m i n i f e r (?)  55  41  Photomicrograph of a calcareous concretion showing general view of phosphatic p e l l e t s  55  42  Photomicrograph of a calcareous showing d e t a i l s of a phosphatic  55  43  E l e c t r o n micrograph showing of a calcareous concretion  microtextures  44  E l e c t r o n micrograph showing of a calcareous eoncretion  microtextures  45  E l e c t r o n micrograph showing of a calcareous concretion  microtextures  46  Deformed f a l c a r e o u s  47  T u r b i d i t e bed w i t h A - d i v i s i o n g r a d e s a l l y upward i n t o E - d i v i s i o n  c o n c r e t i o n e n c l o s e d by  concretions  sand-  i n shale fine-  forming d i s c o n t i -  concretion  concretion pellet  53 53 53 53  57 57 59 59  concretion gradu-  59  Figures  Page  48  T u r b i d i t e bed w i t h A - d i v i s i o n h a v i n g a sharp c o n t a c t w i t h the o v e r l y i n g B - d i v i s i o n  65  49  T h i c k sandstone bed showing s o l e marks  65  50  Specimen of sandstone showing p l a n e - p a r a l l e l lamination  65  51  Specimen of sandstone showing c l i m b i n g r i p p l e laminae  65  52  A s y m m e t r i c a l b r a n c h i n g r i p p l e marks on upper bedding p l a n e of a sandstone bed  65  53  T u r b i d i t e bed showing two C-divisions  65  54  Specimen o f sandstone showing g r a d i n g o f s t r u c t u r e s i n the B- and C - d i v i s i o n s  71  55  Specimen o f sandstone showing c o n v o l u t e lamination  71  56  C o n v o l u t e l a m i n a t i o n on upper b e d d i n g p l a n e  superimposed  o f a sandstone bed  71  57  Organic borings i n shale  71  58  O r g a n i c b o r i n g s on the s o l e of a sandstone bed Loaded f l u t e c a s t and a groove c a s t on the s o l e o f a t h i c k sandstone bed  71  60  F r o n d e s c e n t marks p a r t i a l l y o b l i t e r a t e groove c a s t s on the s o l e of a t h i c k sandstone bed  79  61  A c l o s e - u p o f the f r o n d e s c e n t marks o f f i g u r e 60  79  Scour marks on t h e base of a t h i c k sandstone bed  79  Loaded s c o u r marks on the base of a t h i c k sandstone bed  79  59  62 63  71  (xi)  Figures 64 65 66 67 68  69  70  71  72  73  Page T h r e e g e n e r a t i o n s o f g r o o v e c a s t s on t h e s o l e o f a t h i c k sandstone bed  79  Groove c a s t s o f d i f f e r e n t sizes  82  s h a p e s and  Two g e n e r a t i o n s o f i n t e r s e c t i n g c a s t s w i t h superimposed r i d g e s  groove 82  C l a s t s o f l a m i n a t e d s a n d s t o n e embedded i n c o a r s e - g r a i n e d , t h i c k s a n d s t o n e bed  82  D e f o r m e d c l a s t o f l a m i n a t e d s a n d s t o n e embedded i n c o a r s e - g r a i n e d , t h i c k sandstone bed  82  C l a s t o f laminated sandstone showing r e c u m b e n t f o l d i n g , embedded i n a t h i c k bed o f s a n d s t o n e  82  C l a s t s o f s a n d s t o n e a n d s h a l e embedded i n t h i c k sandstone bed, the former s t i l l connected w i t h the u n d e r l y i n g undisturbed beds  82  C l a s t s o f laminated sandstone showing s l i g h t d e f o r m a t i o n , embedded i n a t h i c k b e d o f sandstone  85  C l a s t s o f f i n e - g r a i n e d s a n d s t o n e and s h a l e showing asymmeyrical f o l d i n g , enclosed i n a t h i c k bed o f sandstone  85  Recumbent f o l d i n g i n s a n d s t o n e a n d s h a l e c l a s t s w h i c h a r e embedded i n a t h i c k b e d of sandstone.  85  74  Complex d e f o r m a t i o n i n sandstone c l a s t s bedded i n a t h i c k bed o f sandstone  75  Sandstone d i k e c u t t i n g through shale  #5  76  Very t h i n d i s c o n t i n u o u s sandstone c u t t i n g through ehale  #5  77  em-  85  dike  Thi«k s a n d s t o n e d i k e c u t t i n g t h r o u g h s h a l e  89  (xii)  Figures  Page  78  Branching sandstone dike  89  79  Sandstone dike showing contorted lamination  $9  80  Exotic block of sandstone embedded i n shale. Shale lamination bends below and terminating against the block  #9  Si &2 #3 84  Exotic block of sandstone embedded i n shale * Shale lamination bends around the block.. Deformed, laminated sandstone clasts enclosed i n shale Photomicrograph of a sandstone showing the replacement of a quartz grain by the c-.lcite cement  89 89 97  Photomicrograph of a sandstone showing the replacement of quartz and feldspar .grains by the clay-size matrix  97  Photomicrograph of a sandstone showing-the replacement of a feldspar grain by the c a l c i t e cement  97  86  Photomicrograph of arkosic wacke showing a volcanic rock fragment  102  87  Photomicrograph of l i t h i c wacke showing shale rock fragments Photomicrograph of feldspathic arenite showing siliceous cement C l a s s i f i c a t i o n triagnle of arenite sandstones  105a  90  C l a s s i f i c a t i o n triangle of wacke sandstones  105b  91  Photomicrograph of quartz arenite  107  92  Photomicrograph of feldspathic arenite  107  93  Photomicrograph of arkosic arenite  107  85  88 89  102 102  (xiii)  Figures 94 95  96  Page Photomicrograph o f a r k o s i c wacke showing c h e r t r o c k fragment  109a  Photomicrograph showing t h e replacement of g r a i n s by the s u r r o u n d i n g c l a y - s i z e matrix  109a  Histograms o f t h e g r a i n s i z e  distribution  of t h e sandstones  ,109b  97  T i l t compensator  109a  98  P a l e o e u r r e n t s map  112  99  T r i a n g l e o f Walker's t u r b i d i t e g r o u p i n g  118  Tables  Page  1  L i s t o f t h e Nanaimo Group f o r m a t i o n s  2  C o m p o s i t i o n o f the Cedar D i s t r i c t F o r m a t i o n sandstones  8 95  1. Ii PRODUCTION A>  Purpose and Scope o f the Present Investigation. The area of study Is situated on the Gulf Islands an e  part of the southeastern coast of Vancouver Island i n the southwestern part of the Province of B r i t i s h Columbia i n Canada ( f i g - 1 ) . In a N'v-SK direction t h i s area extends from just south of the c i t y of Nanaimo on Vancouver Island to the southern part of Saturna Island, a distance of about 43 miles. In a KE-S J direction, It extends from T:  Mayne Island to the western part of Salt Spring Island, a distance of about 15 miles ( f i g .  2).  Currently a study of the Upper Cretaceous Nanaimo Group i s being carried out by the Department of Geology in t h e University of B r i t i s h Columbia, supported by The B r i t i s h American O i l Company Ltd. The author's part of this project concerns one unit i n the Nanaimo Group, the Cedar D i s t r i c t Formation, and the objective of the present investigation was t o study the detailed petrological, sedimentological, and paleogeographica1 aspects of that particular formation. Because turbidites form an important part of the Cedar D i s t r i c t Formation, a large part of t h i s investigation w i l l be concerned with t h i s type o f rock. .  -2-  3  B.  Acknowledgements To D r . R o b e r t E. G a r r i s o n t h e a u t h o r w i s h e s  his  deepest  structive  to  express  thanks f o r c o n s i s t e n t l y e x c e l l e n t a d v i c e , con-  criticism,  s t i m u l a t i o n , s u p p o r t , and  consolation.  Dr. G a r r i s o n ' s p o s i t i o n as a t h e s i s a d v i s o r c o u l d not been f i l l e d  more a d e q u a t e l y .  Pullen f o r h i s help i n t r i p s for  T h a n k s a r e due  a r e a , and  Michael  among t h e i s l a n d s by b o a t  d i s c u s s i o n s i n the f i e l d .  field  t o Mr.  Island.  p a r t i c u l a r l y t o Mr.  and M r s .  w h i l e c a r r y i n g out the f i e l d  T h i s w o r k was  B r i t i s h American  C.  Hindmarch,  w o r k on  s u p p o r t e d by a g r a n t f r o m  and  Saturna The  O i l Company Ltd.,  General Geology  o f t h e Nanaimo Group  This discussion w i l l of  and  To t h o s e i n h a b i t a n t s o f t h e  goes t h e a u t h o r ' s e x p r e s s g r a t i t u d e f o r generous h e l p accomodation  have  be a b r i e f a c c o u n t  of the  geology  t h e Nanaimo G r o u p , d r a w n m a i n l y f r o m p r e v i o u s s t u d i e s o f  these rocks.  a. S t r a t i g r a p h y The  Nanaimo Group r a n g e s  Maestrichtian  ( M u l l e r and  i n age f r o m t h e S a n t o n i a n  J e l e t z k y , 1967).  t h e e a s t c o a s t o f V a n c o u v e r I s l a n d and i s l a n d s t h a t f r i n g e the coast.  I t outcrops  to on  the a s s o c i a t e d  I t o c c u r s i n two  main  areas  4  of outcrop, a smaller area around, the town of Suquash i n the northeastern part of the island, and a large area extending from Campbell River on the east coast of Vancouver Island i n the north to the San Juan Islands i n Washington State to the south.  On the east, the outcrop areas are  bounded by the waters of the Queen Charlotte and the Georgia S t r a i t s , on the west by the mountain ranges of midVancouver Island. The Nanaimo - Comox and the Suquash basins, i n which the Nanaimo Group has been deposited, were part of the Insular Belt of B r i t i s h Columbia (A. Sutherland Brown, 1966, f i g s . 6-2 to 6 - 1 0 ) .  This area has been a s i t e of  tectonism and deposition from Late Paleozoic to the present time.  During Late Paleozoic to Jurassic time, several suc-  cessive eugeosynclinal basins developed.  During Late Cre-  taceous time, a downwarped or dpwnfaulted trough, the Georgia Seaway developed i n the southeastern part of the Insular Belt and was the s i t e of the Nanaimo Group deposition (Sutherland Brown, 1966, p. 8 4 ) . The Nanaimo Group comprises a thick sequence of clast i c rocks consisting of conglomerates, shales, and some coal of mixed continental and marine origin (Usher, 1952).  In  general, the group i s thickest i n the southeastern part of the Nanaimo basin, where i t reaches 10,000 feet and thins toward northwest edge of the basin to about 7,500 feet.  6  In the  t h e Comox Nanaimo J.E.  divided  Muller  Cedar  District  The  lateral rhythmic  the  Group  Permian)  surface  reported  r e l i e f  Hoen, ern  1958)  part The  recorded  up t o a  by them  as' a  part  cycle  of the l i t t o r a l  of  of the  sedi-  formation  Jurassic  ErosLonal  2,000  about  above  440  large;  feet, feet  a  wide and the  examples.  Late  Paleozoic  sedimentary  and/or  r e l i e f  lateral  shales  are the best  v o l c a n i c and  very  and  have  Triassic-Jurassic  i s locally to  each  part  vertical  unconformably  and Late  o f up  trans-  (shaley)  t h e marine  sequence  intrusions.  formable  and grading  by both  the latter,  o f the S i c k e r Group,  acidic  beds  o f t h e second  metamorphosed  Group  complete  a few of the formations  rests  3£),  p.  deposition.  i s marked  among  feet.  of sedimentation";  the turbidite  sandstone-shale  Vancouver  ceous  facies")  1,  "four  i s considered  water  and only  Nanaimo  into  non-marine  consider  deeper  extent;  rocks  basin,  6,000  and  f i g .  The n o n - t u r b i d i t e  lithology  variation,  (1967,  cycles  Formation  they  represent  rocks  with  ("Haslam-type  mentation;  (Early  Group  o f t h e Nanaimo  5,000  between  and J e l e t z k y  formation".  facies  The  measures  and r e g r e s s i v e  "starting  marine  to  Group  t o the northwest  t h e Nanaimo  gressive cycle  basin  volcanicsof Early  along Clapp  this  ( i n  Group  occurs  i n five  separate  W.B.  i n the north-  of the area. Nanaimo  uncon-  (1914)  and Buckham of r e l i e f  Creta-  areas,  7  interpreted by Hqen (195$) as representing separate sedimentary  basins.  These "basins" are the Nanaimo, Comox,  Cowichan, Alberni, and Suquash basins, of which the Nanaimo and the Comox basins are the largest i n area.  A prominent .  ridge of volcanic rocks of the Vancouver Group separates the southern basins (Nanaimo and the Cowichan) from the northern basins (Comox and Alberni).  This ridge l i e s  across Nanoose Bay, about 10 miles northwest of the c i t y of Nanaimo.  J.D. Mackenzie 1922 ( i n Hoen, 1958) believed  that the Comox and Alberni basins were o r i g i n a l l y a single basin-.  Usher (1952) placed a l l of the formations included  i n the Nanaimo Group into two major basins, the Nanaimo south of basin /\ 'Mannose Bay, and the Comox basin to the north. Hence, he grouped the Comox and the Alberni basins ( he did not consider the Suquash basin) i n one basin he called the Comox basin, and the Nanaimo and the Cowichan basins into another basin which he termed the Nanaimo basin. These two major basins have i n general similar faunal and l i t h o l o g i c a l successions,' and during times of maximum marine flooding must have been connected.  However, a separate set  of names has been applied to each of the two basins by Usher (1952).  The following are the reasons presented by  Usher for the separate terminology i n the two basins: - ( l ) Lack, i n the Comox basin, of formations equivalent to some of the lowest i n the Nanaimo basin; (2) differences  NANAIMO  AGE  Maestricl itian  FORMATION  THICKNESS IN FEET 2,000-3,000  LITH0L0GY  Sandstone  -  Gabriola  BASIN  Shale Northumberland  Courcy  Protection  rer Campanian _ or Santonian C-  Sandstone  333(?)-158fc  Shale &  650  • '  Sandstone  Sandstone  Newcastle  215-400  ' Sandstone,Shale; N e w c a s t l e & Dougl a s c o a l seams  o  Cranberry  200-600  Sandstone, , Conglomerate  600-800  Conglomerate, Sandstone  a  —»  District  800-1,000  iges  Gampa nian  Cedar  o  Sandstone Shale  De  $  2,000-2,700  Extension East  Wellington member  Haslam Benson  35 600-1,500 100  Sandstone{Welling t o n c o a l seam Shale Conglomerate  J  Table 1: L i s t of the Nanaimo Group formations i n the . Nanaimo "basin. Modified from Usher (1952) & Wynne (1959).  9  i n the c o a l horizons i n the two areas; between t h e r e s p e c t i v e faunas;- and (4)  (3)  distinctions  difficulties  encoun-  t e r e d i n t r y i n g to apply f o r m a t i o n a l names over a; c o n s i d e r able d i s t a n c e t o s t r a t i g r a p h i c u n i t s t h a t show a pronounced lateral  variation i n lithology.  The f i r s t  be i n c o r r e c t as w i l l be seen l a t e r . formations  i n the Nanaimo b a s i n  w i t h minor m o d i f i c a t i o n s ) . d e t a i l e d microfaunal shown t h a t the lowest  (adopted from Usher, 1952  and macrofaunal i n v e s t i g a t i o n s has formations  of the lowest  (McGugan, 1 9 6 2 ,  and 1 9 6 4 ,  table  Table 1 l i s t s the  More r e c e n t work based on  as o l d as those  1967,  reason proved to  i n the Comox b a s i n are  i n the Nanaimo b a s i n  f i g . 2 , and M u l l e r and J e l e t z k y ,  2),  J.E. M u l l e r  (personal communications) i s i n c l i n e d to  t h i n k o f two major basins o f d e p o s i t i o n : (1)  the Nanaimo-  Comox b a s i n which i n c l u d e s the Nanaimo, Cowichan, Comox, and  the A l b e r n i b a s i n s ;  b.  (2)  the Suquash b a s i n .  Structure  D i s c u s s i o n o f the s t r u c t u r e of the Nanaimo Group w i l l be c o n f i n e d t o the Nanaimo b a s i n s i n c e t h i s r e s e a r c h was c a r r i e d out i n the Nanaimo b a s i n o n l y . The  g e n e r a l s t r u c t u r e o f the Nanaimo Group i n the G u l f  I s l a n d s and v i c i n i t y  i s a northeast  d i p p i n g monocline  10  F i ^ . 3:  Fig.  4:  Figl 5  Two s e t s o f i n t e r s e c t i n g j o i n t s , i n sandstone B e d w e l l Harbour, N o r t h Pender I s l a n d ;  Two s e t s of i n t e r s e c t i n g j o i n t s i n s h a l e . B e d w e l l Harbour, North Pender I s l a n d . V a r i a t i o n i n s p a c i n g of j o i n t s w i t h v a r i a t i o n i n bed t h i c k n e s s , J o i n t s i n t h i c k sandstone beds are w i d e r spaced than j o i n t s i n t h e t h i n n e r b e d s . B e d w e l l H a r b o u r , N o r t h Pender I s l a n d .  11  with  numerous  Toward  the  become  more  (Wynne  1959),  NV/-SE t r e n d i n g  north,  Limbs  folds  tightly  folds  i n the from  dips  ranging  ranging  from  N30°W t o  North  Pender  associated  with  few  numerous  faults.  faults  faults  but  southward  2.  average  and  and  broader  folded with  figure  of  are  folds  northern  part  12°  to  20°,  M55°W.  To  the  Islands, dips  as  of  and  as  basin  average  south,  high  the  on  have  trends  Salt  Spring  7S°were  60°and  recorded. Jointing except and,  for  i n a  has  not  (1914)  Clapp few  places,  who  the  presence  of  the  Cedar  District  Formation,  at  least  two  of  sets  v a r i e s from  joints  are  formation joints  (figs.  tend  closely  c.  spaced  be  has  joints  3  i n the and  4).  Work  been  the  previous  i t was  the  s e d i m e n t o l o g i c a l and  with  intersecting  at  90°  50°.  ones  about  and also  spaced  the  the  rocks  that an  there  angle These  shales  observed  i n the  join-  of  that  thick  the these  beds  and  ( f i g . 5).  Nanaimo  published  sheet  observed  to  workers  irregularity,  parallel  experience  I t was  thinner  on  of  sandstones  more w i d e l y  i n the  Previous  Nothing detailed  to  author's  approximately  present  by  indicated their  From  which  present  mentioned  ting.  are  the  been  prior  Group  to  this  thesis  paleogeographical  on  aspects  the of  12  the Nanaimo Group r o c k s .  Most p r e v i o u s work has f o c u s e d  the s t r a t i g r a p h y and p a l e o n t o l o g y of these r o c k s . d e t a i l e d r e v i e w of  t h i s  on  For  p r e v i o u s work, the r e a d e r i s  r e f e r r e d t o Usher (1952, p . 2 - 6 ) , and t h i s s e c t i o n w i l l  deal  the  o n l y w i t h the major c o n t r i b u t i o n s t o u n d e r s t a n d i n g  of the (1952)  geology o f the Nanaimo Group, drawn m a i n l y from Usher and from more r e c e n t p u b l i c a t i o n s . The  e a r l i e s t work on t h e r o c k s of L a t e Cretaceous  age  a l o n g the s o u t h e a s t e r n c o a s t o f Vancouver I s l a n d began n e a r l y a c e n t u r y ago.  I n t e r e s t i n these r o c k s began w i t h  the d i s c o v e r y of e x t e n s i v e c o a l d e p o s i t s i n them i n T h e i r age remained unknown u n t i l 1&57 Usher, 1952)  1#35.  when Newberry ( i n  s t a t e d t h a t t h e y belonged  t o the. Cretaceous  System. James R i c h a r d s o n made the f i r s t  systematic  strati-  g r a p h i c a l , s t r u c t u r a l , and p a l e o n t o l o g i c a l s t u d i e s o f the Nanaimo Group c o a l f i e l d s and 1876-77).  ( J . Richardson, 1871-72,  1872-73,  He d i v i d e d the s u c c e s s i o n i n t o many r o c k -  s t r a t i g r a p h i c u n i t s t h a t he c a l l e d " D i v i s i o n s " , w h i c h l a t e r came t o be known as f o r m a t i o n s . G.M.  Dawson, i n the course of g e o l o g i c a l e x p l o r a t i o n  o f B r i t i s h Columbia between 1875  and 1$90,  did extensive  work on the c o a l f i e l d s of Vancouver I s l a n d . Cretaceous  He named a l l  r o c k s on e a s t e r n Vancouver I s l a n d the  Group" (Dawson, 1#90).  The  "Nanaimo  f i r s t comprehensive work on  i3  the  invertebrate  f o s s i l s o f t h e group was c a r r i e d out by  Whiteaves i n 1$79 ( i n Usher, 1 9 5 2 ) . vestigations  Clapp made f u r t h e r i n -  o f t h e Upper C r e t a c e o u s , as w e l l as o f t h e  o l d e r , and younger r o c k s o f t h e e a s t c o a s t o f Vancouver I s l a n d i n t h e y e a r s between 190$ and 1917.  He has been c r e -  d i t e d f o r naming t h e f o r m a t i o n s o f the Nanaimo Group i n t h e Nanaimo map-area (Clapp 1911, and 1 9 1 4 ) . I n t h e y e a r s 1945 and 194$, Usher made a d e t a i l e d  pale-  o n t o l o g i c a l i n v e s t i g a t i o n i n t h e Comox and the Nanaimo b a s i n s (Usher, 1952).  He i n t r o d u c e d a f o r m a t i o n a l  subdivi-  s i o n o f t h e Nanaimo Group w h i c h was s l i g h t l y m o d i f i e d from Clapp's ( 1 9 1 4 ) .  Usher's p u b l i c a t i o n  (1952) has an e x c e l l e n t  d e s c r i p t i o n o f t h e f o r m a t i o n s , i n c l u d i n g a s y s t e m a t i c desc r i p t i o n o f t h e e n c l o s e d macrofauna,  R i c h f i e l d O i l Corpora-  t i o n ^ c a r r i e d out mapping o f t h e G u l f I s l a n d s  i n 195$, and  assembled a g e o l o g i c a l map w i t h a s c a l e o f 2 m i l e s t o t h e inch  (Wynne, 1959)• McGugan, i n t h e y e a r s 195$ and 1959 made e x t e n s i v e  s a m p l i n g o f t h e s h a l e y f o r m a t i o n s i n t h e Nanaimo and Comox basins,  and studied, t h e i r f o r a m i n i f e r a l assemblages.  He  s u b d i v i d e d t h e Nanaimo Group i n t o t h r e e zones based on f o r a minifera  (McGugan, 1962 and 1 9 6 4 ) .  J.E. M u l l e r  i n t h e course  of h i s r e g i o n a l mapping on Vancouver I s l a n d f o r t h e G e o l o g i c a l Survey o f Canada, which s t a r t e d i n 1963 and I s s t i l l i n  *4p r o g r e s s , remapped t h e Nanaimo G r o u p . J e l e t z k y ' s work has r e s u l t e d  M u l l e r ' s and J.A.  i n i n t r o d u c i n g a biochrono-  l o g i c a l - l i t h o l o g i c a l r e l a t i o n s h i p bet\^een t h e f o r m a t i o n s in  t h e N a n a i m o , Comox, and t h e S u q u a s h b a s i n s J e l e t z k y , 1967).  and  first by  graded bedding suggested,  structures exhibited  i n t h e Nanaimo G r o u p ,  and t h e presence  especially  of turbidites.  s e d i m e n t o l o g i c a l , and  aspects o f these  D. T e r m i n o l o g y  paleoenvironmen-  formations.  A p p l i e d t o T u r b i d i t e Sequences  The f o l l o w i n g g e n e r a l d i s c u s s i o n w i l l introduce the reader minology, author this  He a l s o  t h a t some more d e t a i l e d w o r k s h o u l d be done on  the p e t r o l o g i c a l , tal  (1967) h a s p r e s e n t e d t h e  D.L. S c o t t  d e s c r i p t i o n o f the sedimentary  some f o r m a t i o n s  (Muller  serve t o  to c e r t a i n aspects of t u r b i d i t e  and t o d e s c r i b e t h e p r o c e d u r e s  ter-  followed by the  i n studying the rocks which are t h e subject o f  investigation. By d e f i n i t i o n t u r b i d i t e s a r e t h e r o c k s o r s e d i m e n t s  d e p o s i t e d by t u r b i d i t y c u r r e n t s . by K u e n e n a n d M i g l i o r i n i  Since the p o s t u l a t i o n ,  (1950), t h a t t u r b i d i t y c u r r e n t s  a r e a l i k e l y mechanism f o r t r a n s p o r t i n g sandy m a t e r i a l s to  deep w a t e r ,  and f o r t h e f o r m a t i o n o f graded  bedding,  many r o c k s o f t h i s n a t u r e h a v e b e e n s t u d i e d i n d i f f e r e n t  -15-  PELITIC  DIVISION  ^E-division^  UPPER  DIVISION O F P L A N E -  PARALLEL  LAMINATION ( WITH  S M A L L CURRENT RIPPLES) (^D-divisionj ^  ^  ^  ^  ^  DIVISION OF C U R R E N T RIPPLE A N D CONVOLUTE  LAMINATION  ^C-divisionj  L O W E R DIVISION O F P L A N E . PARALLEL  LAMINATION  ^B-division^  GRADED  DIVISION  ^A-divisior^  4 Fig.  6:  A complete t u r b i d i t e u n i t and i t s d i v i s i o n s i n an i d e a l t u r b i d i t e . M o d i f i e d from Bouma (1962), Walker (196?), & Hubert (1967). T h i c k n e s s e s o f the i n d i v i d u a l u n i t s may range from a few inches to a few f e e t .  16  parts of the world  and i n d i f f e r e n t p a r t s o f t h e g e o l o g i c  column. Bouma  (1962), i n h i s study o f the f l y s c h  of the A l p Maritimes turbidite unit  deposits  i n E u r o p e , o b s e r v e d t h a t i n a. c o m p l e t e  ( f i g . 6) ( a u n i t h e r e m i g h t r e p r e s e n t  one  o r more b e d s , o f t h i c k n e s s v a r y i n g f r o m an i n c h t o a f e w feet) there  are five divisions,  (1962) and d i v i s i o n s b y W a l k e r are unit  called (1965).  i n t e r v a l s b y Bouma These d i v i s i o n s  as f o l l o w s from t h e bottom t o t h e t o p of the t u r b i d i t e ( r e p r o d u c e d f r o m Bouma 1962, p. 49 w i t h  some m o d i f i -  cation).: a. G r a d e d D i v i s i o n ( A - d i v i s i o n ) : - The b o t t o m  part  o f t h i s d i v i s i o n c o n s i s t s o f s a n d , s h o w i n g more o r l e s s distinct  graded bedding.  This grading  may be  or even absent i f t h e m a t e r i a l i s w e l l s o r t e d .  indistinct The t e x -  t u r e o f t h i s d i v i s i o n i s sandy and sometimes g r a n u l e s pebble's may be f o u n d . present  Occasionally  at the lower contact  and  sole markings are  of t h i s d i v i s i o n ,  and t h e y  range from l o a d c a s t s t o scour marks. b.  Lower D i v i s i o n o f P l a n e - P a r a l l e l L a m i n a t i o n ( B -  division):-  I n t h i s d i v i s i o n p a r a l l e l l a m i n a t i o n due t o  an a l t e r n a t i o n o f more and l e s s c l a y e y dominates. minates.  G r a d i n g may be p r e s e n t , The c o n t a c t  generally gradational.  sand l a m i n a e  but l a m i n a t i o n  prepredo-  b e t w e e n t h e A- and B- d i v i s i o n s i s  17  c. Division of Current Ripple and Convolute Lamination (C-division;:-  This d i v i s i o n consists of cur-  rent ripples, which are i n most cases less than 5 cm thick. A d i s t i n c t fore-set lamination i s often v i s i b l e . Sometimes the ripples are more or less oversteepened or convoluted; convolute lamination, i f present i n the turbidite unit, i s restricted to t h i s d i v i s i o n . The contact between the Band C- divisions i s either sharp or gradational. d. Upper Division of Plane-Parallel Lamination (D-division):-  An i n d i s t i n c t lamination i s characteristic  of t h i s d i v i s i o n , but i f the layer i s weathered or deformed the lamination becomes i n v i s i b l e . s i s t s of a very sandy to s i l t y clay. decrease i n sand content i s v i s i b l e .  The material conSometimes an upward The contact between  the C-division and t h i s d i v i s i o n i s usually very d i s t i n c t . e. P e l i t i c Division (E-division):-  The upper d i v i -  sion of the turbidite unit shows no v i s i b l e sedimentary structures.  A small upward decrease i n grain size and .  sand content may be found.  Often, a rapid upward increase  i n the lime content i s found. in this pelitic division.  Foraminifera may be found  Their number generally i n -  creases with increase of lime content and decrease of grain s i z e .  The contact between the upper two divisions  generally i s completely gradational. Because the  a u t h o r has not been a b l e t o  distinguish  i a  between the upper two divisions i n the f i e l d , i n the present study the upper two divisions have been grouped under one d i v i s i o n which i s called i n t e r t u r b i d i t e d i v i sion (DE-division) (Walker,  1 9 6 ? ) *  The term i n t e r t u r b i -  dite i s suitable f o r the upper -wo divisions because they f  represent deposition of sediments by normal gravity s e t t l i n g between two periods of t u r b i d i t y current deposition.  In discussing the f i e l d techniques and the use of  the logging chart, the author w i l l refer to the divisions by t h e i r respective l e t t e r s (e.g. graded d i v i s i o n i s the A-division, lower d i v i s i o n of p a r a l l e l lamination i s the B-division .... etc. ). The reader should be aware that the above description of the different divisions might not be representive of turbidites i n general a l l over the world, but they describe the turbidites of the Alpe Maritimes i n Europe (Bouma,  1 9 6 2 ) ,  and they show agreement to a large extent  with the turbidites of the present study.  A number of  workers have related the various divisions to flow conditions within a turbidite current, as w i l l be discussed subsequently. E.  Methods of Study The f i e l d phase of t h i s investigation focused on . ••  - 1 9 -  DODD  NARROWS  VANCOUVER  VESUVIUS  ISLAND  DE COURCY  BEDWELL  BAY  SALTSPRING  NORTH  ISLAND  Hbr.  PENDER  SATURNA  ISLAND  ISLAND  FORMATION D€ COURCY  FORMATION  DE COURCY  FORMATION ?  CEDAR  DISTRICT  F O R M A T I O N  O  QUESTIONABLE  C E D A R  DISTRICT  F O R M A T I O N  \  \  7. ?  ?  lOWEH  CONTACT  UNEXPOSED  N O R M A t  C O N TA C T  LEGEND  FAULTED  Sondstone  Cokor««Co„cr.hoo, Soft. Sediment In  Deformation  Sandstone  COLUMNAR  Sandstone Dikes  SECTIONS  OF THE  In S h a l e  V,ojy^° £05=^?  «*«<'»tone  CEDAR DISTRICT FORMATION  SCALE  Conglomerate K »  L S I -  ired  Intervals 2  miles  ll  BRITISH COLUMBIA, CANADA  CONTACT  CONTACT  20  d e t a i l e d measurements o f s e c t i o n s of the Formation i n d i f f e r e n t p a r t s of the s c a r c i t y of outcrops  favorable  two  c o m p l e t e s e c t i o n s , , one  and  one  part  partial  of the  w o r k was  formation)  The  at best,  to the  Systematic i n two  and  This  Field since  rocks  o r by  s e c t i o n s are  shorelines  s t r i k e of the  tend  glacial exposed;  approximately  formation.  Techniques  p e r c e n t a g e and  been dis-  s a n d s t o n e b e d s , as f o l l o w s :  I n p a r t s of s e c t i o n s where s a n d s t o n e beds  are  s h a l e d o m i n a t e s , 5 - f o o t i n t e r v a l s v/ere m e a s u r e d the  persentage of the  c a l c u l a t e d w i t h i n each 5-foot  are  ( f i g . 7).  vegetation  ways d e p e n d i n g on t h e  by J a c o b ' s s t a f f , and  (2)  upper  l o g g i n g o f t h e m e a s u r e d s e c t i o n s has  t r i b u t i o n of the  few  complete section-,  I n l a n d , the  only p a r t i a l  a. F i e l d  (1)  s o i l and  the  study,  on t h e wave c u t c l i f f s ,  s e c t i o n s are found along  perpendicular  carried  questionably  outcrops.  c o v e r e d e i t h e r by  best  Because of  f o r t h i s k i n d of  v/ere m e a s u r e d  conducted mainly  d e p o s i t s , and  area.  District  s e c t i o n , ( r e p r e s e n t i n g o n l y the  these e x h i b i t the best t o be  Cedar  In other  sandstone  was  interval.  p a r t s of s e c t i o n s where s a n d s t o n e beds  abundant, d e t a i l e d i n c h - b y - i n c h  l o g g i n g was  conducted.  l o g g i n g included.measurements of the t h i c k n e s s , c o l o r ,  grain size,  and  sedimentary s t r u c t u r e s f o r each  division  21  within each separate turbidite unit.  Paleocurrent direc-  tions were measured from d i r e c t i o n a l sedimentary structures within the turbidite units and along bedding planes, along with sampling, sketching and photography. A l l of these data v/ere recorded i n a tabulated form i n the f i e l d on a graph paper r o l l .  The appendix at the  end of t h i s thesis shows a sample of a logging chart and i t s explanation, the properties measured and t h e i r symbols. b. Laboratory Techniques Microscopic: Petrographic examination of the different rocks was conducted, with special emphasis on the sandstones.  Quantitative compositional analysis of 26 sand-  stone samples was done by point counting which included counting from 400 to 700 counts per thin section depending on the grain size, the least counts being made on fine-grained sandstones. The size of 100 grains was measured i n 15 sandstone thinsections to determine the size d i s t r i b u t i o n ; no attempt was made to convert the thin-section size d i s t r i bution (number) into the sieve-size d i s t r i b u t i o n (weight) as was done previously by Friedman (195$, and 1 9 6 2 ) , since he delt with well sorted sandstones.  Qualitative  22  microscopic reous  examination  concretion  termining Feldspar  their  of  samples  from  of  seconds into  different were  etching with  sodium  done  and  K-feldspar  sections levels  stained  and  11  calca-  f o r the purpose  the thin  quartz  12  within  sections  hydrofluoric acid  are stained  of  sandstone  of  de-  and  by  con40  Next,  dipping  seconds.  plagioclase  point  five  method  then  s o l u t i o n f o r 40  i s unaffected.  v/as d e t e r m i n e d  The  i n  f o r approximately  fumes  yellow,  samples,  the section  f o r feldspar.  cobaltinitrite  K-feldspars white,  samples  Staining;-  l o c a l i t i e s , sists  was  shale  composition*  Thin chosen  8  them The  feldspars  the percentage  counting  under  of  the  microscope. X-Rqy  Analysis: Five  diffraction  crushing mesh of  samples  analysed of the  each  screen  the  of K a d i r i t e / I l l i t e  v/ere  composition  were  rock  (U.S.  ratio.  selectively  sample,  treated  to  and  Four  f o r the This  s i e v i n g them  Standard), passed  analysed  by  clay mineralogy  clay-size matrix.  sample which were  samples  f o r semi-quantitative  determination samples  shale  through  this  get r i d of the  and  sandstone  mineralogic was  through  collecting  x-ray  the  screen; calcium  done a  by  230  portion A l lt h e carbonate,  23  organic  matter,  possible during  and i r o n  effects  i n order  of f l o u r e s c e n c e from  the process  of x-raying.  centrifuged  i n order  sample  than  less  oxides  t o recover  or equal  to minimize  these  materials  The  samples  were  that  portion  of the  t o two microns,  any  which  next  was  then  x-rayed. Electron  Microscopy: Three  were  examined  replicas stage of  of part  replica  this  part  textures  2,  Island State  situated  area  a  any f o s s i l  AND  DISTRICT  Island,  1965).  t o study  Purpose micro-  STRUCTURE  District  o f t h e Nanaimo  of figure  making  FORMATION  o f t h e Cedar  southeast  after  nannoplankton.  on t h e southeast  5 miles  On V a n c o u v e r  was  on t h e northwest,  o n t h e map  with  and Fischer,  THICKNESS,  CEDAR  t h e mouth  Washington  shown  THE  outcrop  from  valley  (Honjo  samples  surfaces by the two-  of the investigation  OF  Vancouver  not  method  concretion  microscope  o f t h e samples'  DISTRIBUTION,  The  is  the electron  and recognize  •  tends  under  calcareous  Formation  River delta to Sucia  (fig*  2).  of Saturna  on  Island  i n  Sucia  Island,  ex-  Island  but i s  2.  the formation  nearly north-south  trend  underlies a extending  wide  from  the  24  mouth sing was  of  Nanaimo  through f i r s t  valley there of  the  are  the  posed  2  by  several  3  Vancouver  and  occurring  on  part  Mudge the  of  limbs  the  area  the  beds  11°  32°,  and  the  short  distance  near  the  soft  sediment  to  nose  measure  plexities been  cal  Survey  On belts,  a  by  Canada  i s not  one  on  fact  J.E.  Spring the  few  places  i s also  shores the  Dodd  Narrows,  (only  here).  In  the  varies  from  rapidly  within  a  the  beds  are  located  did  not  a  Muller  of  the  thickness  of  1010  part  ( f i g .  and  of  the  communication),  upper  the  1967  of  the  of  attemp  because  i n  the  which  author area  ex-  of  The  here  northern  a  portions  because  But  Island,  at  but  and  this  the  this  anticline,  (personal  exposed  that  formation  and  anticline  angle  changes  above.  representing  Salt  an  plunging  i n  the  pas-  d r i f t ,  It  i s exposed  at  the  section  measured  thickness base  to  exposed  plunging  deformation.  the  of  dip  by  surrounding  a  strike  mentioned  has  The  due of  of  the  outcrops,  on  and  Within  1914).  east,  formation  latter to  w e l l  Islands  (where  largely  (Clapp,  the  Harbour  1914).  scattered  f a i r l y  to  area  Clapp,  River  miles  Ladysmith  covered  small  Nanaimo  to  i s  are  to  D i s t r i c t  CH.  formation  formation  along  upper  Cedar  defined  the  the  the  River  comfeet  Geologithis  formation.  2).  formation  outcrops  northeastern  part  of  i n  two  the  25  i s l a n d where i t forms 11°  t o 62°;  s e v e r a l minor f o l d s w i t h d i p s  from  i n t h i s area o n l y the upper p a r t o f the  for-  mation i s exposed.  The  second b e l t  extends from Vesuvius  Bay on t h e n o r t h w e s t c o a s t o f t h e i s l a n d t o Ganges H a r b o u r on t h e s o u t h e a s t c o a s t . m a t i o n i s w e l l exposed j a c e n t low c l i f f s In  Along t h i s b e l t , the  o n l y on t h e b e a c h e s  o f Ganges H a r b o u r  A  o f t h e sequence  sand,-  was  c o v e r e d by  Bay,  beach  I n t h e Ganges H a r b o u r - r e g i o n t h e b e d s  s t e e p l y , a s s u m i n g a v e r t i c a l a t t i t u d e and  l y being overturned, (fig. The  north-  thick-  f e e t h a s b e e n m e a s u r e d i n Ves v i u s  w h e r e o n l y 19% g r a v e l and  t o $0°.  ad-  Bay.  V e s u v i u s Bay, t h e beds d i p v e r y s t e e p l y t o the  n e s s o f 1503  dip  and t h e  and V e s u v i u s  east,- t h e d i p a n g l e v a r y i n g f r o m 71°  for-  occasional-  2).  u p p e r 150-200 f e e t o f t h e f o r m a t i o n a l s o o u t -  c r o p s on t h e n o r t h and n o r t h e a s t c o a s t o f P r e v o s t I s l a n d , f o r m i n g a narrow cliffs. the  s t r i p a l o n g t h e b e a c h and t h e  I t i s exposed  nearby  h e r e on t h e s o u t h w e s t e r n l i m b o f  T r i n c o m a l i A n t i c l i n e , the a x i s of which l i e s  waters of the Trincomali Channel. I s l a n d d i p f r o m 2$° It  t o 47°  i n the  Beds on P r e v o s t  t o the southwest,  2).  (fig.  a l s o o c c u r e s as a n a r r o w b e l t on t h e s o u t h e r n  c o a s t o f Mayne I s l a n d , f o r m i n g t h e b e a c h and t h e c l i f f s w h i c h r a n g e f r o m 40  t o a b o u t 100  feet  nearby  high.  2 6  About t h e upper  2 0 0 f e e t o f t h e f o r m a t i o n a r e exposed  here,  l y i n g on t h e n o r t h e a s t e r n l i m b o f t h e T r i n c o m a l i A n t i c l i n e and d i p p i n g w i t h a n g l e s f r o m The f o r m a t i o n f o r m s  3  3  °  to  4  5  northeast  °  (fig,2)..  the core of the T r i n c o m a l i  A n t i c l i n e i n the L y a l l V a l l e y of Saturna I s l a n d , thus the base, o f t h e f o r m a t i o n i s n o t e x p o s e d . the  f o r m a t i o n i s exposed  cliffs  On t h e same i s l a n d ,  a l o n g t h e b e a c h e s and t h e n e a r b y  on t h e s o u t h e r n c o a s t , w h e r e i t l i e s  e a s t e r n l i m b o f t h e f a u l t e d N o r t h Pender  on.the n o r t h -  A n t i c l i n e , and .•  d i p s n o r t h e a s t w i t h angles v a r y i n g from 2 4 ° t o 31°. the of  l a t t e r area, i f ' the conglomerate t h e exposed  (fig.  7)  s e c t i o n d o e s n o t b e l o n g t o the  In  a t t h e base Cedar  D i s t r i c t F o r m a t i o n , t h e t h i c k n e s s t h e n i s - 333 f e e t , w i t h a b o u t 37% c o v e r e d b y v e g e t a t i o n , s o i l ,  and b l o c k s of  sandstone from t h e o v e r l y i n g DeCourey F o r m a t i o n But i f t h i s conglomerate b e l o n g s to Formation of  t h e Cedar  (fig. 2 ) .  District  (as B r e i t s p r e c h e r , 1 9 6 2 , concluded i n h i s study  t h e f o r m a t i o n i n S u e i a I s l a n d ) , the t h i c k n e s s of  Cedar  D i s t r i c t Formation w i l l  present author f e e l s that t h i s t h i c k e r t h a n 2 0 f e e t j and hsg conglomerate)  the  be more t h a n 333 f e e t . eonglemerate  The  (which i s  e h a r a e t e r l i t i e f s o f a beach .  does not b e l o n g t o t h e Cedar  D i s t r i c t Ft)r1ft&>  t i o n expo.sed he,re,, -wh&gh 2fcs 'ailment '9h^r*e^y % ,:  ^H$bi?ci'& e C  27  On three the  North  Pender  belts.  The  Island  f i r s t  and t h e second  Anticline from the  around  the Bedwell island.  feet  mation South  a  Port  measured;  at angles  Pender  Island  visited  a l l t h e above  along  FOSSILS,  a  extends coast  River  of  t h i c k n e s s o f 1 5 #4 lower  Bedwell  one b e l t  contact  Harbour,  along  ( f i g .2).  outlined  District  formation; Saturna  1964, The  AGE,  of the f o s s i l s Formation and almost  and Sucia  occurrences and  belt  Pender  the  for-  On  the north-  The a u t h o r  l o c a l i t i e s ,  might  except  and t h e exposures  has f o rt h e  on  South  Island,  Most  on  third  of  of the  51° t o 60° n o r t h e a s t .  o f an a n t i c l i n e  t h e Nanaimo  3.  Cedar  from  limb  of the North  but a faulted On  coast  t o the west  l o c a l i t y  i t forms  limb  The  southeast  greater thickness.  dips  Pender  the core  Browning.  latter  eastern  area  forms  outcrops' i n  on t h e southwestern  at the northern  Harbour  In this  has been  obscure  the  lies  Trincomali Anticline  island,  the formation  AND  that  have  came  out from  District  recovered  from  the  the shaley  part  of  f o s s i l s  but there  islands,  B r e i t s p r e c h e r 1962, Cedar  been  a l l of these  Islands,  on t h e other  CORRELATION  (Usher  were  a r e some  found  sparse  1952, McGugan  and M u l l e r and J e l e t z k y  Formation  macrofauna  1962 1967).  i s composed  28  almost  entirely  pelycepods, Scaphopods  to  the  were  and  The Pender, f i g .  7.  find  coccoliths Five  c o n c r e t i o n s were  Campanian the by 1952,  by  a l l the  Jeletzky,  Vancouver  Island,  marine  barren",  the  electron  benthonic  age  foramini-  see  1962  table  Saturna,  Islands are  considering the  who  This  McGugan,  on  to  workers  formation.  1967),  samples  considered  previous  the and  been  s e c t i o n s measured  S p r i n g , and Saturna  of  ammonites  M u l l e r and  shale  coccolithsi  visible  has  shales  Three  under  B r e i t s p r e c h e r , 1962,  stratigraphic Salt  examined  c o n t a i n no  paleontology some  a  coccoliths,  conspicuously  Formation  age  with  of  recover  communication).  and  be  to  written  District  type,  G e o l o g i c a l Survey  1968,  also  micro-  i n the  samples  to  Cedar  On  to  concretions.  they  Breit-  ostracods.  "proved  but  the  dominant  samples  (Usher,  1964,  r e p o r t e d by  the  California  indicated  fers,  are  Jolla,  investigated was  hoped  important.  Breitsprecher,1962),  and of  most  cephalopods,  Regarding  i n La  Burky,  Late  Island.  1964,  the  been  States  calcareous  of  Sucia  had  the  United  a l l the  The  are  the  microscope,  be  and  which  t e e t h have  occurrences  to  of  foraminifers  calcareous  sent  (David of  on  author  laboratory but  shark  1962  rare  The and  and  mollusks,  gastropods  benthonic  (McGugan, few  and  (1962)  sprecher fauna,  of  shown  1. North i n  conglomerate  29  and  the u n d e r l y i n g rocks  as p a r t o f t h e  (the l a t t e r  Cedar D i s t r i c t  are  Formation,  (1962) d i d on S u c i a I s l a n d , and  covered as  by  water)  Breitsprecher  assuming t h a t the  minimum  t r u e t h i c k n e s s of the Cedar D i s t r i c t  F o r m a t i o n measured  B r e i t s p r e c h e r on  S u c i a I s l a n d i s 800  feet instead of  feet  thickness i s questionable  (the l a t t e r  because  800  F o r m a t i o n on S a t u r n a  feet.  trict  I s l a n d may  reach  Cedar  as much as  A c c o r d i n g l y , the t h i c k n e s s of the Cedar D i s -  F o r m a t i o n a p p e a r s t o i n c r e a s e f r o m S u c i a and  I s l a n d s toward North  P e n d e r and  o t h e r words from s o u t h e a s t whether the  to northwest.  T h e r e i s no way t h a t c o u l d be  margin of the  f e e t are  formation  correlated laterally  North  P e n d e r and  But  towards the  area,  i n t o members study  o f t h e u p p e r 250  Salt Spring Islands  northwest  Narrows, t h i s  sequence i s not  section there  i s composed o f s h a l e .  sequences are a l s o present  study  throughout the  composed o f s i m i l a r a p p e a r i n g  sequences.  towards  exposed.  to d i v i d e the  a r e a , w i t h the p o s s i b l e e x c e p t i o n f e e t i n the  I t i s unknown  f o r m a t i o n becomes t h i c k e r o r t h i n n e r  s i n c e o n l y t h e u p p e r 1010  Saturna  Salt Spring Islands, i n  Dodd N a r r o w s i n t h e n o r t h w e s t e r n  which are  1200  of  s t r u c t u r a l c o m p l i c a t i o n s ) , then the t h i c k n e s s of the District  by  present,  i n other  to  300  sections  turbidite i n the and  the  Dodd entire  Similar turbidite stratigraphic  levels  30  of the S a l t S p r i n g , North t i o n s , but  P e n d e r , and  Saturna  they are u s u a l l y t h i n n e r than the  Islands sec-  turbidite  i n t e r v a l a t t h e t o p o f t h e f o r m a t i o n on S a l t S p r i n g North  Pender I s l a n d s . On  s e c t i o n s ( f i g . 7),  the s t r a t i g r a p h i c  between the Cedar D i s t r i c t as used a r e f e r e n c e l i n e . line, but  and  and  the  the DeCourcy Formations  T h i s i s n o t meant t o be a  s i n c e t h e r e i s no p a l e o n t o l o g i c a l c o n t r o l  i s used because t h i s  t i o n s , whereas the lower  c o n t a c t was  4. The  time  available,  exposed i n a l l sec-  P e n d e r I s l a n d and  i n t h e Dodd N a r r o w s s e c t i o n , and Island  unexposed  p o s s i b l y a l s o i n the  section.  LOWER AND  Cedar D i s t r i c t  UPPER CONTACTS Formation  l i e s b e t w e e n two  sand-  stone f o r m a t i o n s , the DeCourcy Formation  at i t s top,  the P r o t e c t i o n Formation  Contacts  t h e s e u n d e r l y i n g and tional,  and  is  contact w i t h the P r o t e c t i o n For-  m a t i o n i s f a u l t e d on N o r t h  Saturna  contact  at i t s bottom.  o v e r l y i n g u n i t s a p p e a r t o be  with grada-  the sandstone beds i n the Cedar D i s t r i c t  m a t i o n i n c r e a s e i n t h i c k n e s s and downwards t o w a r d  the adjacent  number b o t h u p w a r d s  units.  and  Forand  31  Fig,  .8: . P e b b l y mudstone o f S a t u r n a I s l a n d . Dark o b j e c t s ( a r r o w s ) a r e s l a t e c l a s t s and pebbles of b a s i c igneous r o c k s . M ^ l k y q u a r t z p e b b l e s c a n be s e e n a t t h e ' c e n t e r of the l e f t h a l f o f t h e p i c t u r e . Note concentric c o n c r e t i o n a r y weathering of the s h a l e m a t r i x (upper r i g h t c o r n e r ) . The s c a l e i s 3 i n c h e s l o n g .  Fig.  9:  Fig.  10:  P o r t i o n of a conglomerate l a y e r t h a t underl i e s t h e p e b b l y mudstone i n f i g . S. Note the abundance o f m i l k y q u a r t z p e b b l e s . Other p o r t i o n s o f t h i s l a y e r have c o a r s e r pebbles'and cobbles. Saturna I s l a n d . C o n t a c t o f the Cedar D i s t r i c t Formation ( t o t h e l e f t o f t h e hammer), and t h e P r o t e c t i o n F o r m a t i o n ( t o t h e r i g h t o f t h e hammer). Beds d i p a t 78° t o t h e l e f t . V e s u v i u s B a y . - S a l t S p r i n g Island...  F i  3  .  10  32  A.  Lower The  is  suming not  at  the  belong  half;  which  the (2)  lower of  with  Cedar  exposed between  and  In  a  of  f o r a a  which  assigns  to  Harbour  part  of  the  and  Protection  In Vesuvius  on  lower  part  of  stone  (bed  t h i c k n e s s ranges  an  average  from  a  The  10).  beds  formation  inches) of  an  inch  contact with  i s drawn  sandstone (fig.  1.7  fraction  inches). mation  of  the  Bay  at  the  Formation  mudstone to  Island,  section  Formation,  the  a  does  and  Cedar  a  (fig.8)  sequence  the  as-  lower  mile  conglomerate  District  ( f i g .  9),  underlying formation. North  dark  Cedar  the  distance of  the of  Saturna of  belongs  discontinuity  the  of  base  pebbly  i s faulted,  structural  the  pebble-cobble  Bedwell  lower  (3)  coast  District  the  District  l o c a l i t i e s :  to  author  sandstone  Cedar  at  contact  the  southern  thickness,  Formation;  the  conglomerate  l i e s  feet  of  following  the  i s well  and  4#  contact  the  Along  contact  of  lower  exposed (1)  Contact  Pender  grey,  District  Island,  s i l t y  the  shale  beds  Formation l i e  against a  very  thick-bedded  Formation. Salt  Spring  consists from  and to the  0.3  shale 33  Island,  the  of  interbedded  to  5.7  (bed  inches  inches,  thickness and  sandwith ranges 5  averages  underlying Protection  p o i n t where  the  increases abruptly to  thickness of  more  than  3  Forthe  feet  33 Fig.  11: Sandstone beds a t the base o f t h e DeCourcy F o r m a t i o n ,near t h e c o n t a c t w i t h t h e u n d e r l y i n g Cedar D i s t r i c t Formation. Vesuvius Bay. S a l t S p r i n g I s l a n d .  Fig.  12: C o n t a c t ( j u s t above t h e hammer) b e t w e e n t h e DeCourcy Formation and t h e u n d e r l y i n g Cedar D i s t r i c t Formation. Dodd Narrows, Vancouver Island.  Fig,  Fig.  13:  Concentric concretionary weathering i n the shale of the Cedar D i s t r i c t Formation. Bedwell Harbour, North Pender Island.  U : Shale sequence cut d i k e . Note t h e l i g h cretions indicated Narrows, Vancouver  Fig.  by i r r e g u l a r sandstone t colored calcareous conby t h e arrows. Dodd Island,  15: T y p i c a l t u r b i d i t e sequence o f i n t e r b e d d e d shal e and sandstone beds, w i t h h i g h sandstone percentage. S c a l e on t h e r i g h t i s 3 f e e t l o n g . Bedwell Harbour, North Pender Island.  34 B. U p p e r C o n t a c t In  t h e t h r e e l o c a l i t i e s mentioned  is typically Sandstone  above, t h i s  more g r a d a t i o n a l t h a n t h e l o w e r c o n t a c t .  beds u s u a l l y i n c r e a s e i n t h i c k n e s s upward.  Where t h e s e s a n d s t o n e  b e d s r e a c h a t h i c k n e s s o f more t h a n  3 f e e t , and where t y p i c a l l o n g e r found, t h e upper  turbidite  s t r u c t u r e s a r e no  contact of the formation w i t h the  o v e r l y i n g De C o u r c y F o r m a t i o n i s d r a w n ( f i g . On Mayne I s l a n d , Sandstone  i n contrast, this  b e d s change a b r u p t l y f r o m t h i n - b e d d e d  very thick-bedded  most De C o u r c y  Dodd N a r r o w s ,  t h e upper  I s l a n d around the  contact i s extremely sharp.  shale, which  Formation,  lies  below massive, v e r y thick-hedded sandstone  5.  Here,  composes a l m o s t t h e e n t i r e  p a r t o f t h e Cedar D i s t r i c t  t h e De C o u r c y F o r m a t i o n  ,  Formation  Formation.  dark grey s i l t y  directly  (about  (over 3 f e e t t h i c k ) i n the lower-  Along t h e east coast o f Vancouver  exposed  11).  contact i s sharp.  6 i n c h e s t h i c k ) i n t h e topmost Cedar D i s t r i c t to  contact  (fig.  of  12).  GROSS LITHOLOGY  The C e d a r D i s t r i c t  Formation i s a r e l a t i v e l y  sequence o f a l t e r n a t i n g marine  thick  s h a l e s and s a n d s t o n e s . -  S h a l e c o m p r i s e s a p p r o x i m a t e l y 73% b y t h i c k n e s s o f t h e  35  measured p o r t i o n s . Calcareous  Sandstone i s second i n abundance.  c o n c r e t i o n s occur throughout most of the  sec-  t i o n , commonly a s s o c i a t e d w i t h s h a l e but a l s o found c i a t e d w i t h sandstones.  A bed of p e b b l e - b r e c c i a ,  i n g f i v e i n c h e s t h i c k , i s found o n l y i n North Island section.  v a r y i n g shape and A. The  size.  Shale Cedar D i s t r i c t s h a l e s are grey, b l u i s h grey to  s i l t y t o sandy, and and  G e n e r a l l y they  are  t h i n s e c t i o n s c o n t a i n black spots  carbonaceous m a t t e r .  r a t e d , p o s s i b l y due cement.  cobbles  a l o n g w i t h sandstone c l a s t s of  b r o w n i s h grey when f r e s h and d r y .  pyrite  Island  contains.a  range of v e r y a n g u l a r t o w e l l rounded pebbles,and of v a r y i n g c o m p o s i t i o n  averag-  Pender  The b a s a l 4$ f e e t of the Saturna  s e c t i o n i s composed of pebbly mudstone t h a t  asso-  of  They are h i g h l y i n d u -  to the v e r y f i n e - g r a i n e d s i l i c e o u s  They show f i n e l a m i n a t i o n , and  concentric concretionary weathering  commonly.posses  ( f i g . 13)•  I n t e r v a l s of s h a l e range i n t h i c k n e s s from  continuous  s e c t i o n s hundreds f e e t i n thickness.., w i t h no c l e a r b e d d i n g except f o r the l a m i n a t i o n ( f i g . 14), t o w e l l d e f i n e d l a y e r s i n t e r b e d d e d w i t h sandstones ( f i g . 1 5 ) , t o mere p a r t i n g s s e p a r a t i n g s u c c e s i v e sandstone beds. The  cumulative  frequency  of the t h i c k n e s s of  727  . -36Cumulative  PROBITS  Fig.  16  ..  Percentage  39  shale Pender  Islands,  plotted  on  IS).-  and  ( i . e ; DE-division)  beds  grouped  are  also  thickness  of  about  enough  be  p l o t t e d on  The is  three  plots  has  graded  also  beds  1967),  of  thickness  sedimentation ness  show  normal.  A  for  (e.g.  of  unlike  course  abundant  of  the  has  quartz  shales  petrographic  been  and, and  present  i n  some  feldspars.  i n almost  not  a  abundant curve.  distribution relation-  interbedded  (1959, i n  with Hubert,  (1967).  Hubert  comprehensive  survey  sedimentation varves,  tend  loess  that to  units  many  show  thick-  normal." fractions  determined  microscope.  constituents, quartz  abundance,  normal  origins  the  mineralogy  the  therefore,  The  the  that  'turbidites,  '!It i s apparent, units  are  i s  17,  reaching  frequency  v a r i a t i o n s shown by  log  under  they  (1966), a n d a  North  l6j  (figs.  beds  shales  after  and  class intervals^  (1953), N e d e r l o f  l6l)-,  Spring  paper  log  are  of  are  but  fluctuations that  size)  as  inch  cumulative  (1962), S c o t t  origins  stated:  a  Salt  shale  feet;  reported  (1957, p .  different  etc.),  log  few  shales  Bokman  McBride  Pettijohn of. t h e  the  been  by  a  three  of  approximiately  ship  one  logarithmic probability There  to  into  from  and  samples, Pyrite  a l l samples  (sand  feldspars chlorite  and  s i l t  semiquantitatively  M i c a s .are  and  to  the  are  i s as  most  second  abundant  carbonaceous give  the  i n  dark  matter grey  40  color  to  the  shale. of  the  shales finer  than  2  and  the  results  that  i l l i t e  Fractions been 23  x-rayed, 59  to  percent,  kaolinite 4  32  morillonite  from  method  f o r determining  ted  used  from  notes  University, from  i960,  and  obtained the  by  1962,  by  plied  as  multiply (3)  these  clay  1959,  from  mineralogy  Warshaw,  measuring  the  intensities  These  the  intensities peak  half  height  height.  of  the  above These  mont-  was  The adop-  at  Duke  (summarized and  percentages of  001  the and  peaks  a  from  24.  to  Rosenberg,  montmorillonite, kaolinite, The  7  course  1965-1966,  i n  ranges  percent,  percentages  196l).  at  For  width (2)  chlorite  have  base  Roy  were  peaks  chlorite were  line  measurements  of  i n  obtained and  the  were  multi-  follows:  (1) peak  35  to  Roy  sample.  width  9  and  measuring  peak  i n a  Kunze  from  and  Carolina  Warshaw  i l l i t e ,  each  given  North  Freas  to  show  microns  at  montmorillonite, multiply half  height  For  chlorite  and  by  2.7.  For  kaolinite,  by  height  by  0.71.  i l l i t e ,  follow  peak  follow  step  one  step  but  one  but  multiply  by  1.0. These percentage was  results  were  of  mineral  each  determined..  added out  f o r each of  the  sample, above  and  four  the  minerals  K a o l i n i t e / i l l i t e r a t i o contour map o f . the shale of the Cedar D i s t r i c t Formation.,;y ^ fj; :  L  :  42  The x-ray d i f f r a c t i o n data also indicate that the k a o l i n i t e / i l l i t e r a t i o decreases from the Dodd Narrows  ;  Saturna Island, North Pender Island, and Mayne Island toward Vesuvius Bay on Salt Spring Island ( f i g . 1 9 ) . This r a t i o has been used by Parham and Austin study of the shales of the  (196?)  i n their  Glonwood Formation, South-  eastern Minnesota to determine the direction of the source area which supplied the clays i n t h i s unit. was based on previous work by Parham  (1966)  Their work on the clay  mineral assemblages i n modern and ancient sediments, where he showed that " i n basins of sediment accumulation kaolinite i s concentrated closer to shore with respect to i l l i t e , and i l l i t e reaches maximum abundance seaward of k a o l i n i t e " .  I f the above i s true, f i g . 1 9 suggests  that Vesuvius Bay area on Salt Spring Island was the most distant area from the paleo-shoreline relative to the other l o c a l i t i e s where k a o l i n i t e / i l l i t e ratio i s higher. B. Sandstone Sandstone comprises the bulk of the non-shale portion of the Cedar D i s t r i c t Formation.  I t has a grey  to greenish color, and varies from coarse grained to very fine grained sandstone, occasionally becoming s i l t y , especially i n the C-division of the turbidite units. This section of the thesis deals largely with f i e l d occurence  43  Fig..20:  Fig. 21:  Fig. 22:  Shaley part of the Vesuvius Bay section just below the middle of the section. Sandstone percentage i s about 5%. Vesuvius Bay, Salt Spring Island. Turbidite sequence of alternating sandstone beds with thinner shale beds. High sandstone percentage. Vesuvius Bay-, Salt Spring Island. Alternating sandstone beds with thicker shale beds. Low sandstone percentage. Bedwell Harbour, North Pender Island.  Fig. 23:  Thick massive sandstone bed. Note a sandstone dike injected from below the sandstone bed • and cutting through the underlying shale. Dodd Narrows, Vancouver Island.  F i g , 24:  Fig. ...2 5:  Turbidite sequence of alternating shale and sandstone. Note the l a t e r a l uniformity i n bed thickness. Bedwell Harbour, North Pender Island. Turbidite bed showing repetition of i t s d i v i - sions.. B-division (Bj at the lower half of the bed i s followed by thin G-division (C), then a second B-division (B), and the rest of the bed i s composed of C-division (C). Bedwell HarbourNorth Pender Island.  u and d i s t r i b u t i o n of sandstones; d i s c u s s i o n of sedimentary s t r u c t u r e s and d e t a i l e d p e t r o g r a p h i c data are presented in following  sections.  The percentage of sandstone v a r i e s both v e r t i c a l l y throughout  the f o r m a t i o n and h o r i z o n t a l l y throughout the  outcrop area, • In the Vesuvius Bay s e c t i o n ,  sandstone  comprises about 44% by t h i c k n e s s of the measured p a r t . W i t h i n one 350 f o o t i n t e r v a l j u s t below the middle of t h i s s e c t i o n , sandstone averages 5%  ( f i g . 20); i n other  i n t e r v a l s , e s p e c i a l l y the t o p 800 f e e t , sandstone averages about 70% by t h i c k n e s s , w i t h t h i c k sandstone beds a l t e r n a t i n g with t h i n n e r shale beds ( f i g s . 21 and 26)., In the Bedwell Harbour  s e c t i o n o f North Pender I s l a n d , the  sandstone averages 25% by t h i c k n e s s of the measured part,, and, as i n Vesuvius Bay vertically  s e c t i o n , the percentages v a r i e s  ( f i g s . 15 and 22)*  Saturna I s l a n d , sandstone  On the southern p a r t of  comprises 20% by t h i c k n e s s of  the measured p a r t , w i t h the b a s a l 48 f e e t l a c k i n g . s a n d stone beds (except f o r e x o t i c sandstone Along Dodd Narrows on Vancouver the top 1010  clasts).  Island, with only  f e e t of the f o r m a t i o n exposed,  sandstone  forms o n l y 5% by t h i c k n e s s (sandstone d i k e s are not considered i n t h i s f i g u r e ) .  There are o n l y a few t h i c k beds  (3 to 6 f e e t t h i c k ) of sandstone present i n t h i s  section,  )  45  thus  the typical  present  i n other  and  23).  has  not been  lar  to that  On  section  on  thickness  Pender  l a t e r a l l y  outcrop which i n width  beds  have  of  fraction  a  irregular sole  here of  have  i s usually 24).  o f an  No  a  sandstone  appearance  when  Harbour  they  due  even  t h e area' o f 300  than  pinching  a l t h o u g h many  planes  i s simi-  remarkably  more  lateral  even  inch,  bedding  o f no  14  15).  (fig.  beds  beds  (figs.  of the Bedwell  Island  observed,  lower  shale  and. a r e c o n t i n u o u s w i t h i n  (fig.  been  part  sandstone  and  the percentage  but the outcrop  o f the upper North  of sandstone  i s not present  Island,  measured,  feet  have  500  to  out of a  thickness  o f them  to loading  these  have  and  other  marks* The  thicknesses  variation, sequence feet,  from  t o beds  classified (1) nating have range  thick  and  average  from  2 1 , 24,  laminae  show  thick, beds.  within  large a  thick  of about  the latter Bed  a  due  thickness  7  to the  can be  types: sequences  sandstone thickness  a fraction and  beds  having thickness  9 feet  In flysch-like shale  an  o f two 3  sandstone  t o beds  about  into  of successive  thin  of shale,  amalgamation  15,  sections  Mayne  Individual  the  alternation  25).  beds,  sandstone  o f about  of an  inch  of rhythmically  4  to 5  t o about  beds  generally  inches, 2  feet  alter-  with (figs.  a 5,  46 (2)  In some intervals of the section where sand-  stone percentage i s very low and shale i s the dominating lithology, sandstone bed thickness averages about an inch, and varies from thin laminae to 5 inches (figs. 20 and  22). (3)  Beds that have a range i n thickness from 2 to 7  feet are also present.  They are found at the middle and  top of the formation, especially at Vesuvius Bay.  In the  Vesuvius Bay section, of Salt Spring Island, there i s also a 330 feet i n t e r v a l of very thick bedded sandstone (up to 7 feet t h i c k ) , which commonly shows soft sediment deformation (figs. 26 and 27).  Very thick beds of sand-  stone (average of 5 feet i n thickness) are also found i n the Dodd Narrows section of Vancouver Island, and are usually associated with sandstone dikes ( f i g . 23)'. Regarding thicknesses of the A through E divisions within t u r b i d i t e units, the cumulative frequency of the thicknesses of 163 B-divisions and 704 C-divisions from 728 t u r b i d i t e units from Salt Spring and North Pender Islands sections,- grouped into one inch class i n t e r v a l , i s plotted on logarithmic probability paper ( f i g . 16, and 18).  17,  There are also a few B-divisions reaching a  thickness of a foot and a half, but they are not abundant enough to be plotted on a cumulative frequency curve.  hi  Distribution of the C-division i s closer to log normal than that O f the B-division.  A log normal relationship  of the B- and C-divisions i s reported by Hubert  (1967).  These sandstone beds exhibit a variety of primary sedimentary structures which are discussed i n d e t a i l i n a following section. C. Pebbly Mudstone on Saturna Island. The lowermost 4$ feet of the Cedar D i s t r i c t Format i o n on southern Saturna Island i s a chaos of c l a s t i c materials of a l l sizes and compositions embedded i n a shale matrix ( f i g . 8 ) , The lower 25 feet of this i n t e r v a l consist of shale which contains isolated pebbles and cobbles of different shapes, varying from very angular to very well rounded. Milky quartz and basic igneous pebbles and cobbles tend to be well rounded, the angular fragments are metamorphic rocks which are commonly dark blueish-grey slates.  Also  scattered throughout this i n t e r v a l are sand and granulesize fragments of the same composition as the larger fragments.  Sandstone clasts of varying size and shape (size  varying from a sandstone lump a fraction of an inch i n diameter to blocks a few feet across) are present, showing no l o c a l i z a t i o n to a certain horizon; they are commonly i n t r i c a t e l y folded, the result of soft sediment deformation,  48  and  resemble  the  "the  present  are  calcareous  Also found size  i n the sorting  tures, set  and At  the  of  In  and  Accompanying  fragments. feet  and  sandstone The present position lying  The  interval  position  the  to the  the  this  8  to  i n the of  pebbles  no  struc-  deltaic, shows  feet O  S  and  to  of  s i l s  fore-  lamina-  possibly  cepha-  these a  and  rounded to  of  rounded  cobbles  especially  the 25  feet  i s the  dis-  and  f o s s i l  i t with  the  48  folded  clasts  of  matrix.  i s closely and  bed.  stratigraphic  c h a o t i c and  shale  the  pebbles  i t s  coquina  becomes  correlate  are  broken  along  thickness decrease and  Interbroken  form  mudstone  this are  inches,  northwest  southeast  interval  conglomerate,  the  used  presence  composition  of  6  pebbly  c r i t e r i a  embedded  i n this  of  angular  the  type  i s  imbricate  F  gastropods,  to  thick.  There  matrix  23  top  a  interval  of  the  top  half  same  weathering.  concentrated  this  appearance  shale  become  strike,  no  fossiliferous.  the  the  formation. and  (1957).  Crowell  conglomeratic,  The  pelecypods,  fragments mile  and  the  of  locality,  sandy  of  concretions of  29),  and  typical  same  overfolds"  of  observed.  shells.-  A  2$  concretionary  fragments  shell  are  were  i s more  lopods  parts  (figs.  which  beds,  tion  val  other  slump  the  pebbles  and  identical of  the  to  cobbles the  directly  abundance  of  comunder-  milky  49-  quartz pebbles and cobbles ( f i g . 9 ) . Crowell (1957) has described several sequences with characteristics very similar to those of the Saturna Island pebbly mudstone. He ascribed t h e i r emplacement to "a downslope movement under gravity '. 1  The present author-  concurs with Crowell's hypothesis for the mechanism of emplacement, that i s slumping due to gravity, which resulted i n the absence of sorting and the great contrast i n size and shape of the pebbly mudstone constituents'.  The  following i s a model f o r the emplacement of the pebbly mudstone of Saturna Island, modified from Crowell (1957), Pebbles and cobbles of contrasting shape and compos i t i o n were carried by a high density t u r b i d i t y current and deposited on a sloping, muddy bottom.  Some of the  pebbles and cobbles sank into the underlying mud.- This loading of the mud by the coarse elastics and the occurrence of a slope i n i t i a t e d a gravity movement of the mud and overlying coarse e l a s t i c s .  The flow.was viscous  enough to prevent any size sorting, but not viscous enough to prevent complete mixing of the different size fractions. During the course of this gravity mass movement, clasts of sandstone from the underlying sediments were peeled o f f , r o l l e d up, and incorporated with the flow, and formed the folded sandstone clasts.  50  Fig.  26:  Fig.  27:  Thick bed of sandstone encloses a deformed thinl y bedded sandstone clast (derived from the underlying beds?). The sandstone clast grades i n grain size from coarser at the bottom of the hammer to f i n e r toward the head of the hammer. Vesuvius Bay, Salt Spring Island. Thick bed of sandstone encloses a t h i n l y laminated clast of sandstone. The sca.le i s one foot long, Vesuvius Bay, Salt Spring Island.  Fig. 28:  Fig.  29: :  Fig. 30:  Pebbles of different shape, size, and compos i t i o n , from the pebbly mudstone .of Saturna Island. Specimen from the upper part of the pebbly mudstone where sand percentage increases. I t contains fragments of a l l sizes of organic shells (arrows). Saturna Island; Turbidite bed with i t s basal A-division composed of breccia. Note the sharp contact between A and B-divisions to the l e f t of the hammer head. Bedwell Harbour, N rth Pender Island. n  Fig. 31:  Polished specimen of the t u r b i d i t e breccia of f i g . 30, Two graded cycles are present; t h e i r approximate contact i s indicated by the clashed l i n e , Bedwell Harbour, North Pender Island.  51 D. Turbidite Breccia A breccia bed with granule and pebble size clasts was found at the base of a turbidite unit ( i . e . A-division) i n the Bedwell Harbour section of North Pender Island,  I t was found to be continuous along strike within  the outcrop area for a distance of about 3 0 0 to 400 feet* It i s covered with the B-division of p a r a l l e l lamination, but the contact between these two divisions i s irregular (fig. 3 0 ) .  Breccia thickness averages about 5 inches.  The constituent fragments are very angular ranging i n shape from equidimensional to rodlike ( f i g . 31). Color i s mainly buff grey and brownish grey.  The breccia clasts  are composed of a great variety of rock fragments and minerals.  Rock fragments, which are the dominant consti-  tuent, are shale, limestone, chert, and volcanic, granit i c , and metamorphic rocks.  Mineral i d e n t i f i e d i s quartz.  Also present are fragments of organic s h e l l s . The breccia shows an overall grading i n grain size from i t s bottom to i t s top, with a sudden decrease i n size as the B-division of p a r a l l e l lamination i s reached ( f i g . 3 0 ) , however, size grading also continues through the B-division, Within the overall grading of the breccia, at least two cycles of grading are observed ( f i g . 3 1 ) . Fragments show no preferred imbrication.  52  A p o s s i b l e mode itA  t r a n s p o r t a t i o n as a t r a c t i o n  defined  by Dzulynski  saltation eddies below by  zone  a mature  and f l o w s  move  as a  turbidity i n the t a i l  between  A-  E.  carries than  current.  i s defined v e r t i c a l and  type  of flow,  materials  Consequently,  of the  the traction  the sharp,  carpet  sediment  which  the finer  of the overlying turbidity  concretions  the formation  f o rt h e basal  inches  flow")  t h e o v e r l y i n g sediments  Calcareous  32  dense  current  and  of the  non-gradational  deposit  traction contact  a n d B - d i v i s i o n s i l l u s t r a t e d i n f i g . 30.  were  118 f e e t  associated with  a n d 33).  Their  found  t o be very  i n a l l the l o c a l i t i e s  are not restricted  a r e found  (figs.  with  In this  the coarser  carpet  by turbulent  the l a t t e r  current  size.  Concretions  They  few  turbidity  Calcareous  throughout except  current;  on t o p o f t h e coarse producing  a s : "The  the overlying turbulent  eventually overtake load  1962  breccia, i s  (traction  i s not invaded  i n grain  slower  carpet,  and  as a  carpet  load  material  from  grading  traction  w i l l  which  of this  carpet  and Sanders,  turbidity  (1965)  Walker  the  .,.  of any size  horizontal  i t s  o f emplacement  exposed  special  both  sandstone  longest  t o several feet,  studied,  a t Vesuvius  to a  dimension  type  common  Bay.  of  rock,  and shale ranges  '  from  and o c c a s i o n a l l y theyform  a  a  53  Fig. 32:  Fig. 33:  Calcareous concretions (outlined by dashed lines) enclosed i n a sandstone bed. Note thickening of the sandstone bed around the concretions. Vesuvius Bay, Salt Spring Island. Calcareous concretion embedded i n shale. 0 e foot scale. Vesuvius Bay, Salt Spring Island. n  Fig.  34:  Fig.  35:  Calcareous concretion with a thin very f i n e grained sandstone bed crossing i t (sandstone bed indicated by arrows). Scale i s one foot long. Vesuvius Bay, Salt Spring Island.  • Calcareous concretions joined to form a discontinuous bed. Bedwell Harbour, North Pender Island.  Fig. 36: • Calcareous concretion with i t s long dimension cutting shale lamination. Note organic borings (indicated by arrows). Vesuvius Bay, Salt Spring Island. Fig.  37:  Calcareous concretion enclosing a bivalved s h e l l . Pencil points to a broken s h e l l fragment.- Vesuvius Bay, Salt Spring Island.  54  d i s c o n t i n u o u s bed o f j o i n e d c o n c r e t i o n s ( f i g s . 33, 34, and 35).  They e x h i b i t a w i d e r a n g e o f s h a p e s , f r o m  disc-shaped,  to g l o b u l a r , t o tube-like'; others are l e n s -  shaped as seen i n t h e o u t c r o p  34,  and 3 6 ) .  surrounding beds.  The f i r s t  whose l o n g d i m e n s i o n s  34j  a r e a l w a y s p a r a l l e l and  t h e surrounding bedding and 3 5 ) .  filled  concordant  o r l a m i n a t i o n ( f i g s . 32>, 3 3 ,  The s e c o n d i s t h e t y p e t h a t h a s a random  d i s t u r b i n g the surrounding bedding Both types  relative to the  and most common i s t h e t y p e  o r i e n t a t i o n of the long dimensions,  ing  ( f i g s . 33,  i n two d i m e n s i o n s  They have two modes o f o c c u r r e n c e  to  biconvex  c u t t i n g through  and .  and l a m i n a t i o n ( f i g . 3 6 ) *  c o n t a i n animal burrows o r b o r i n g s t h a t a r e  w i t h sand and s i l t  burrowing  o f t h e e n c l o s i n g beds,  suggest-  t o o k p l a c e w h i l e t h e c o n c r e t i o n s and t h e  s u r r o u n d i n g sediments  were s o f t ; a l t e r n a t i v e l y ,  m i g h t be b o r i n g s i n t o a n a l r e a d y l i t h i f i e d  these  concretion  l y i n g on o r n e a r t h e s e a f l o o r . I n e i t h e r c a s e , t h i s . o b s e r v a t i o n and o t h e r e v i d e n c e s  m e n t i o n e d beloxv i n d i c a t e  d i a g e n e t i c f o r m a t i o n o f the' c o n c r e t i o n s .  early  Some o f t h e c o n -  cretions contain shells of bivalved invertebrates ( p o s s i b l y Inoc.eramus). shells  (fig.  37),  o t h e r s have t a b u l a r  ( p o s s i b l y a m m o n i t e s ) , a n d some o t h e r s c o n t a i n f r a g -  ments o f b r o k e n  shells.  They f r e q u e n t l y c o n t a i n  laminae  55  Photomicrographs of Calcareous Concretions (Sample numbers at end of captions) Fig.  38:  Fig.  39:  Fig.  40:  Fig.  41:  Fig.  42  F o s s i l foraminifers(?) i n calcareous concret i o n , f i l l e d with pyrite (black) and sparry c a l c i t e (white). Crossed nicols. Vesuvius Bay, Salt Spring Island. (V12). D e t r i t a l grains of quartz, feldspar, mica, and clay minerals, i n a calcareous concret i o n . Crossed nieals. Vesuvius Bay, Salt Spring Island. (V21). Planktonic foraminifer (?) (in the center) surrounded by other f o s s i l foraminifers(?). The matrix (or cement) i s composed of f i n e grained (micritic) c a l c i t e . Crossed nicols. Vesuvius Bay, Salt Spring Island. ( V l 6 ) . Phosphatic pellets (indicated by arrows) i n calcareous concretion. The matrix i s composed mainly of m i c r i t i c c a l c i t e and d e t r i t a l quartz and feldspar. Note how the pellets are bent around a foraminifer (?) test, Plane polarized l i g h t . Vesuvius Bay, Salt Spring Island. (V21). Photomicrograph to show, i n d e t a i l , part of one of the phosphatic pellets i n f i g . 4 1 . White grain i n the center i s quartz. Dark grains are phosphatic materials, the l i g h t grains are clay minerals. Crossed nicols. Vesuvius Bay, Salt Spring Island (V2l).  56  which continue into the surrounding shale or sandstone; these iaminae exhibiting the same sedimentary structures as i n the surrounding rocks ( f i g . 3 4 ) . The concretions are grey i n color and are composed mostly of c a l c i t e with some clay minerals and pyrite ( f i g . 33).  When crossed or surrounded by s i l t y shale or sand-  stone beds, they usually have a high percentage of the same d e t r i t a l quartz, feldspar, and other minerals that constitute the surrounding rocks ( f i g . 3 9 ) . They commonl y contain circular and e l l i p t i c a l tests of microfossils (possibly foraminifers) which arc usually f i l l e d with sparry c a l c i t e , and occasionally by pyrite (figs. 3 $ and 40).  Phosphatic p e l l e t s v/ere observed i n two concretions. They are globular to elongate and have a size range from 5 to 2. mm ( f i g . 4 1 ) . Their colour i s l i g h t brown under polarized l i g h t , and greenish brown under crossed n i c o l s . Phosphatic material i s also found disseminated throughout the concretions around the p e l l e t s .  D e t r i t a l quartz,  feldspars, and clay minerals within the concretions are also found enclosed i n the pellets mixed with the phospha.t i c material ( f i g . 4 2 ) . In concretions that have been intersected by s i l t y or sandy laminae, the pellets are confined to the very fine grained c a l c i t e - r i c h  parts of  57  F i g . 43:  F i g , 44:  E l e c t r o n micrograph of a calcareous c o n c r e t i o n . M i n e r a l s w i t h high r e l i e f are d e t r i t i a l q u a r t z , s i l i c a t e m i n e r a l s , o r rock f r a g m e n t s . R o d l i k e g r a i n s are p r o b a b l y micaceous minera l s . The l o w - r e l i e f g r a i n s a r e c a l c i t e m a t r i x ( o r cement). B l a c k g r a i n s are p o s s i b ly illite.. Note replacement of t h e d e t r i t a l g r a i n s by t h e c a l c i t e cement a l o n g t h e i r i r r e g u l a r boundaries. B e d w e l l Harbour, North Pender I s l a n d . ( P 3 1 ) . Electron embedded s i z e and Island.  • m i c r o g r a p h showing d e t r i t a l g r a i n s i n c a l c i t e cement o f v a r i a b l e g r a i n shape. V e s u v i u s Bay, S a l t S p r i n g (VSE7).  56*  the  concretion.  served  t o be  suggesting former  I n one  bent  that  was  around  this  of  textures  of the calcite  grains.  The  surrounding  the replica.  ly  replaced  44)  fined  to only  Grain  boundaries  irregular the  and  d e t r i t a l The  a  cement  their >  In  part  ob-  ( f i g .  41),  the test  show  regarding  while  the  some  s i l i c a t e  higher  (figs.  43  etching grains  of the grain  minerals, than  are  p a r t i a l cement i s  con-  43).  ( f i g .  are generally  of the calcite  they  preparation  calcite  boundary  the  because  during  the  d e t r i t a l  the replacement  replacement  interlocking  44),  commonly  by  grains  r e l i e f  and  con-  the detailed  the enclosed  boundaries  showing  highly  cement  with  grains.  cement  i s composed  size  numerous  was  of the calcareous  and  with  d e t r i t a l  The  calcite  up  The  v a r i a b l e shapes  9.0  pellet test  on  (quartz,  the acid  and  about  grains  by  along  and  cement  stand  calcite  affected  43  information  d e t r i t a l  of  (figs.  some  fragments)  less  settled  electron micrographs  reveals  are  a forarainifer  pellet  cretions  rock  section, a  soft.  Study  or  thin  with  i s v a r i a b l e and microns grains  (figs.  appear  of calcite  their  boundaries  ranges  from  43,  and  quite  small inclusions.  44  grains  hummocky  highly  about 45). and  of  0,1 The  irregular embayed.  micrort to' surface-  irregular  of t h  with  59  Fig..  45:  Fig.  46:  E l e c t r o n micrograph showing b r a n c h i n g r o d l i k e g r a i n s w i t h c a l c i t e g r a i n s (low r e l i e f g r a i n s ) between them. V e s u v i u s Bay, S a l t S p r i n g I s l a n d . (VSE7). Deformed c a l c a r e o u s c o n c r e t i o n ( i n d i c a t e d by a r r o w s ) e n c l o s e d i n a s a n d s t o n e bed t h a t u n derwent s o f t - s e d i m e n t d e f o r m a t i o n . V e s u v i u s Bay-, S a l t S p r i n g I s l a n d ,  Fig/  47:  A - d i v i s i o n (A) g r a d e s g r a d u a l l y upward, i n t o B - d i v i e i o n ( B ) . The d a r k r i n d i s c a u s e d by seepage of sea w a t e r i n t o t h e sandstone along fractures. V e s u v i u s Bay, S a l t S p r i n g Islandi  66  The  black grains  extracted  clay minerals  t o what Grim illite.  (1953,  rals  calcite  up w i t h h i g h  cement  t o t h e 001 p l a n e .  s e p a r a t i o n a l o n g 001 c l e a v a g e c a l c i t e between these  planes  G a r r i s o n , 196$, p e r s o n a l  I n f i g . 45  (e.g. organic  during diagenesis,  of the calcareous  concretions, (very  solutions, are localized  around a  nucleus  s h e l l s o r d e t r i t a l g r a i n s ) t h a t may o r may  leave a r e l i c  ( f i g s . 33 a n d 3 7 ) . extensive  d e t r i t a l g r a i n s by secondary c a l c i t e .  During  this  Some o f t h e s e  con-  ( f i g . 32); the  t e n d s t o be t h i c k e r a r o u n d them s u g g e s t i n g  c o n c r e t i o n and t h e e n c l o s i n g s a n d s t o n e h a r d e n e d than the surrounding  precipi-  replacement o f  c r e t i o n s a r e found w i t h i n sandstone beds  compaction.  ( R. E .  stage) during which, carbonates p r e c i p i t a t e d  t a t i o n t h e r e was a p p a r e n t l y  bed  forceful  by c r y s t a l l i z a t i o n o f  suggests an e a r l y d i a g e n e t i c o r i g i n  from i n t e r s t i t i a l  not  planes  these  communication).  Regarding the genesis  early burial  44,  a r e p e r h a p s s e c t i o n s o f m i c a c e o u s mine-  cut perpendicular  author  relief  ( f i g s . 43,  g r a i n s a r e c o n n e c t e d i n a manner w h i c h s u g g e s t s  the  similar  p.120 and 121) h a s i d e n t i f i e d a s  The r o d - l i k e g r a i n s t h a t s t a n d  e s p e c i a l l y 45)  are probably  a n d have s h a p e s somewhat  r e l a t i v e t o the surrounding and  4 3 , 4 4 , a n d 45)  (figs.  that the earlier  sandstone, t h e r e f o r e escaped  I n summary, t h e f o l l o w i n g c r i t e r i a  strong  suggest  61  an early diagenetic o r i g i n for 1.  these concretions:  Organic borings and burrows f i l l e d with sediment  of the surrounding beds. 2.  Thickening of beds where concretions occur.  3.  Their deformation when present i n beds showing  soft sediment deformation, 4.  ( f i g . 46).  Undeformed r e l i c s (bivalvecl shells) enclosed i n  the concretions ( f i g . 37)• G. Mill Ier  (1967,  p.  154),  i n a discussion of the car-  bonate contretions enclosed i n mudstones and shales poor i n carbonates, stated " I t seems probable that most of the concretions started to form i n the shallow b u r i a l (and early) stage of diagenesis, because the enveloped r e l i c s of organisms are commonly not deformed." Lippmann  (1955,  i n G. Mttller  1967,  p.  154)  explained  the genesis of calcareous concretions as follows: "Ammonia resulting from the decomposition  of organisms or  amines gives r i s e to a strongly alkaline reaction i n the v i c i n i t y of the animal (or plant) embedded i n the sediment, and the pH i s increased.  As the s o l u b i l i t y of the  carbonates decreases with increasing pH, they are precipitated on the f o s s i l from the i n t e r s t i t i a l solutions, which have been saturated with carbonates by dissolving the disseminated calcareous material (also present i n  62  predominantly a r g i l l a c e o u s s e d i m e n t s ) .  Thus here the  car-  bonate c o n c e n t r a t i o n of the pore s o l u t i o n decreases i n comparison to the the d i f f e r e n c e  surrounding environment,  and because of  i n c o n c e n t r a t i o n , more carbonate i s  s t a n t l y d i f f u s e d to the f o s s i l . by a constant growth of the  This p r o c e s s ,  con-  accompanied  c o n c r e t i o n , continues  until  the p r o d u c t i o n of ammonia s t o p s , or u n t i l t h e r e a r e no more d i s s o l v e d carbonates a v a i l a b l e The p y r i t e rocks,  present  vicinity.,"  i n these c o n c r e t i o n s and the  i s probably the r e s u l t  prevalent  i n the  i n the v i c i n i t y  host  of the r e d u c i n g c o n d i t i o n s  of the decomposing organisms.  The s i g n i f i c a n c e of the r a r e phosphatic m a t e r i a l noted above i s not known.  The author has not observed i t  a s s o c i a t e d w i t h other types of rocks i n the  to be  formation.'  Phosphatic m a t e r i a l i n sediments i s t y p i c a l l y a product of slow d e p o s i t i o n or n o n - d e p o s i t i o n ; i t s w i t h the  association  c a l c a r e o u s c o n c r e t i o n s may i n d i c a t e  formed d u r i n g i n t e r v a l s  6.  the  latter  of reduced sedimentation  rates.  SEDIMENTATY STRUCTURES  The sandstones and s h a l e s of the tion exhibit  Cedar D i s t r i c t  a wide range of sedimentary s t r u c t u r e s .  range from primary s t r u c t u r e s formed e i t h e r  by the  FormaThey filling  63  of  marks  (e.g.  made  (e.g.  graded  before  beds,'  (e.g.  slump  rents  flowing  A.  Internal  cession  unit  ferent  from  always  f o r occasional t h e same  i t s bottom  (e.g.  structures  of the world,  and  deposition  loaded  cur-  turbidity of soft  currents); sediments  Turbidite.Units  been i n a  a  limited  observed. fixed  order  discussed  earlier show  but the majority  been described  i n sediments  or  within  of the i n  a l lthe tend  suc-  certain  f i g . 25)  Terminology  number  These  r e p e t i t i o n of a  to top.  have  ripple  dikes).  of the t u r b i d i t e units  them.  current  deformational  t u r b i d i t e unit,  has been  or  parts  sediment  density  Within  to exist  (divisions),  These  after  to f o r c e f u l injection  structures of  high  have  within  Some  more  by  sediments  (e.g. clastic  structures  paper.  formed  the  t o g r a v i t a t i o n a l movements  structures  tend  during  current  individual t u r b i d i t e units,  (except  structure  soft  Structures  sedimentary  structures  the  due  fissures  Within of  either  r e s u l t i n g from  structures  through  lamination,"  structures), or drag over  and/or  bottom  out of the transporting  parallel  clue  o n a muddy  marks),  etc.-'); t o s t r u c t u r e s burial  structures  current  of sole  of the sediments  lamination,  to  erosive  d i f f e r e n t kinds  settling  and  by an  dif-  this possible  to lack  one  i n different  ranging  i n age  from  64  the P r e c a m b r i a n  to present  Humbert b i b l i o g r a p h y ,  (see  P H . H . Kuc-nen and F . L .  1964; the r e a d e r may a l s o r e f e r  to  K»0. Emery, 1964 f o r d i s c u s s i o n o f t u r b i d i t e s from P r e cambrian t o  present).  Walker (1965) has a t t r i b u t e d the v a r i a t i o n i n the n a t u r e o f the graded d i v i s i o n (e.g. w e l l d e f i n e d or crude g r a d i n g i n A - d i v i s i o n ) t o the type o f t u r b i d i t y from w h i c h g r a d i n g has f o r m e d .  current  He a l s o r e l a t e s t h e v a r i a -  t i o n i n the n a t u r e o f the o t h e r d i v i s i o n s  (e.g.  variation  i n types of current r i p p l e l a m i n a t i o n i n C - d i v i s i o n ) the hydrodynamic c o n d i t i o n s o f the c u r r e n t .  He has  (Walker, 1967) i n t e r p r e t e d the hydrodynamics o f the ferent  d i v i s i o n s by analogy w i t h the f l o w regimes  Simons and o t h e r s ,(1965)*  to  dif-  of  I n h i s view* t h e A- and B-  d i v i s i o n s were formed w i t h i n the Upper f i o w regimej C - , D--, and E - d i v i s i o h s w i t h i n the lower f l o w  the  regime.  a . Graded D i v i s i o n ( A - d i v i s i o n ) Out o f the i n d i v i d u a l 746 t u r b i d i t e u n i t s  measured  i n the upper 1$5 f e e t and the lower 118 f e e t of t h e Vesuv i u s Bay s e c t i o n o f S a l t S p r i n g I s l a n d , and the upper 174 f e e t of the B e d w e l l Harbour s e c t i o n o f Pender I s l a n d , 20 graded d i v i s i o n s were r e c o r d e d .  Additional units, with  A - d i v i s i o n o c c u r i n o t h e r p a r t s o f the s e c t i o n s where t e m a t i c measurements  only  o f the d i f f e r e n t  sys-  d i v i s i o n s were not  65  Fig. 4 8 :  Fig. 4 9 :  Fig. 50:  Fig. 51:  Fig. 52  Fig. 53:  Massive A-division (bottom of the pencil) l i e s below laminated B-division with a sharp contact. Vesuvius Bay, Salt Spring Island. Thick, f a i n t l y laminated, graded sandstone bed. with i t s sole showing flute casts (a), bounce casts (b), and f i n e , closely spaced groove casts (c). Current from l e f t to right. Bedwell Harbour, North Pender Island. Plane-parallel lamination (B-division) caused by alternating dark, t h i n , fine-grained and l i g h t , thick, coarse-grained sand laminae. The top i inch shows cross lamination (Cd i v i s i o n ) . Note organic reworking. Bedwell Harbour, North Pender Island. Climbing ripple laminae of McKee (1965), (C-division). Vesuvius Bay, Salt Spring Island, Upper bedding plane of sandstone bed showing s l i g h t l y asymetrical branching ripple marks. Mayne Island. Two superimposed C-division. Note the' d i f f e r ence i n thickness and types of structures between the lower thin, and the upper thicker • C-divisions. Vesuvius Bay, Salt Spring Island,  66  made;"  these  are mainly  very  about 3 t o 4 f e e t ) w i t h  t h i c k beds  crude g r a d i n g ,  (average  and u s u a l l y  l a r g e c l a s t s o f deformed s h a l e and sandstone 27).-  Other than these  very  thick,  thickness contain  ( f i g . 26 and  graded b e d s , two t y p e s  o f g r a d i n g have been o b s e r v e d : (1)  A - d i v i s i o n g r a d e s upward g r a d u a l l y w i t h o u t  sharp contact  a  into the overlying B-division (fig..47).  (2) A - d i v i s i o n l i e s below B - d i v i s i o n w i t h a sharp w e l l defined  contact  ( f i g . 4$).  In both cases,  t h e A-»division h a s a s h a r p lower  tact with the underlying Walker  DE-division.  (1965, p . 13) s u g g e s t e d p o s s i b l e m e c h a n i s m s t o  e x p l a i n these suggests,  two t y p e s  of grading.  The f i r s t  has been formed by t h e r e w o r k i n g  part o f a pre-exi5ting ted i n the formation  A-division.  t y p e , he  o f t h e upper  This reworking,  resul-  o f a p l a n e - p a r a l l e l d i v i s i o n (B-  d i v i s i o n ) at the top of A - d i v i s i o n , grading  con-  The s e c o n d t y p e o f  i n h i s view has been formed by primary  deposition  o f A- a n d B - d l v i s i o n s f r o m t h e t u r b i d i t y  c u r r e n t , w i t h no  reworking.  current  I n both cases,  ble f o rtheir For  formation  the t u r b i d i t y  h a s no t r a c t i o n  t h i c k graded beds  ( f i g . 49),  p o s t u l a t e d d e p o s i t i o n from t u r b i d i t y tion carpet.  carpet.  where t h e r e  l a m i n a t i o n w i t h i n the A - d i v i s i o n , Walker  responsi-  i s faint  (1965, p.11) h a s  current with a trac-  I n h i s o p i n i o n t h e shear a p p l i e d by t h e  67  current the  i s too low to maintain  coarse  b.  sediments  Lower  continuous  a t the bottom  Division  motion  of the  of Plane-Parallel  within  current.  Lamination  (B-division) This l a t t e r tion  d i v i s i o n always  i s present.  tite by  thin,  ( f i g . 50).  t h i s  the size  Some  planes  within  166  show p a r t i n g  t h i s  Only  were  on S a l t a  (20)  few  by A-division.  turbidite units  units  have  sharp,  division  (when  Kuenen  planar  A-division  (1953,  p.  20$  reported  199).  p.  of the  degree  coarse  of size  gra-  lamination  turbidite  and North B-divisions form  base). over  i s absent;  a r e underof  146  turbidite  They  l i e with  the underlying  f i g .  and Sanders  Pender  the base  o f t h e 746  contact  1049)  bio-  also  i n t h e 746  (146)  at t h e i r  lower  was  and  spliting.''  Island  rest  ( i . e . about  laminae  lineation along  o f t h e 166  The  B-divisions  almost  some  recorded  Spring  alterna-  f r a c t i o n a t the base  the size  d i v i s i o n upon  B-divisions  measured  Island. l a i n  units  when the.  containing  (1965,  of the coarse  at i t s top, indicating  ding.  laminae  and Sanders  than  by the  colored  of lamination  d i v i s i o n i s larger  fraction  units  63),  p.  light  colored  kind  the A-division  i s caused  thick,  dark  This  (1962,  Bouma  Occasionally of  Lamination  of coarse-grained,  fine-grained,  overlies  25).  (1965,  p.  199)  a DE-  68  suggested that p a r a l l e l lamination was formed by the fluctuation or pulsation of the current v e l o c i t y . Walker (196$, p. 13) thought they were formed i n the "plane bed  with movement" part of the current regime of Simons et a l . (1961), either by primary deposition from the current  ( f i g . 4 8 ) , or by reworking of previously deposited sediments ( f i g . 4 7 ) . c. Division of Current Ripple and P a r a l l e l Lamination (C-division) This d i v i s i o n i s very abundant i n the t u r b i d i t e units of the Cedar D i s t r i c t Formation.  It was recorded i n 707  out of the 746 t u r b i d i t e units measured, and forms the basal part of 77$ of the measured t u r b i d i t e units ( i . e . 77$ of the units start with the C-division at t h e i r base). Thickness of this d i v i s i o n varies from a f r a c t i o n of an inch to 10 inches, averaging about an inch and a half. Figures 16, 17, and 18 show the cumulative frequency of the thicknesses of 707 C-divisions measured i n the Vesuvius Bay section of Salt Spring Island, and the Bedwell Harbour section  of North Pender Island.  The three lines  approach log normal d i s t r i b u t i o n , with a marked deviation at the 5-7 inch i n t e r v a l i n the North Pender section (fig. 18), indicating thet C-divisions with t h i s thickness range are rare.  69  Grains comprising the sediments of t h i s d i v i s i o n t  mostly i n the coarse s i l t and  are  • "  .  t o the v e r y f i n e sand  classes,  show a c r u d e g r a d i n g f r o m c o a r s e a t t h e b a s e  of the  d i v i s i o n to f i n e at i t s top. S t r u c t u r e s observed i n t h i s d i v i s i o n (1)  include:  C u r r e n t r i p p l e s and t h e i r a s s o c i a t e d  cross  lami-  nation. (2) Convolute  lamination.  M o s t o f t h e C - d i v i s i o n s e x h i b i t e i t h e r one o f t h e a b o v e s t r u c t u r e s , b u t some o f them h a v e b o t h  structures  associated together* Almost a l l the cross l a m i n a t i o n found ,in t h i s  divi-  s i o n i s o f t h e t y p e c a l l e d b y McKee ( 1 9 6 5 , p « 7 6 , f i g s . and d) "pseudobeds"± o f b o t h h i g h and l o w a n g l e .  4c  This  k i n d of c r o s s l a m i n a t i o n has r e s u l t e d from the m i g r a t i o n of the r i p p l e s accompanied above,  by d e p o s i t i o n o f s e d i m e n t s  from  r e s u l t i n g i n what i s c a l l e d by McKee -(1965)  "climbing ripple  laminae", ( f i g .  51).  which consists e n t i r e l y of C - d i v i s i o n , three dimensions  (fig.  O n l y one t h i n  bed,  shows r i p p l i n g i n  52).  These c u r r e n t r i p p l e s range i n w a v e l e n g t h from  two  i n c h e s t o about a f o o t , t h e i r a m p l i t u d e ranges from a f r a c t i o n o f an i n c h t o a b o u t two  inches.  i n a single set forming a t h i n C-division  They o c c u r (fig.  53,  C - d i v i s i o n ) and u s u a l l y f o r m s i n g l e s e t s o f c r o s s  either lower  70lamination "suggesting rippling",  no f a l l - o u t of sediments d u r i n g  (Walker, 196$,  p.15).  s e v e r a l s e t s on top of each o t h e r  They may  a l s o occur i n  ( F i g . 53, upper C - d i v i -  s i o n ) , or i n the form of c l i m b i n g s e t s of r i p p l e cross lamination;  drift  the l a t t e r " s u g g e s t s a f a l l out  sediments d u r i n g o r i m m e d i a t e l y a f t e r the i n i t i a l t i o n of r i p p l e s " , l a s t two  of forma-  (Walker, 1 9 6 5 , p.15), ( f i g * 5 1 ) .  The  forms tend to make a r e l a t i v e l y t h i c k C - d i v i s i o n *  C o n v o l u t e l a m i n a t i o n may  a l s o o c c u r i n one  I n cases where r i p p l e and  convolute  or more s e t s .  l a m i n a t i o n both  o c c u r i n the same d i v i s i o n , t h e r e i s a c o n s i s t e n t c a l arrangement of these s t r u c t u r e s .  The  verti-  C-division  s t a r t s w i t h v e r y broad r i p p l i n g at the bottom w h i c h grades upward i n t o narrower r i p p l e s w i t h g r e a t e r a m p l i t u d e ,  and,  at the top o f the d i v i s i o n , the r i p p l e s tend t o show convolution,  (fig.- 53, upper C - d i v i s i o n ; and f i g ; 54).  I n a d d i t i o n t o t h i s v e r t i c a l sequence, i t was observed t h a t one  s t r u c t u r e c o u l d grade h o r i z o n t a l l y  a l o n g the s t r i k e of the bed  i n t o another s t r u c t u r e  c u r r e n t r i p p l e l a m i n a t i o n may luted lamination) . convoluted  also  grade l a t e r a l l y t o convo-  W a l k e r , ( 1 9 6 5 , p.12)  l a m i n a t i o n forms i n c o h e s i v e  suggested t h a t bottom sediments;  when the sediments l a c k such c o h e s i v e n e s s , l a m i n a t i o n w i l l be formed.  (e.g.  current  ripple  I f t h i s i s the case, the  71  Grading nation w nation w convolut nisms.  of structures from p l a n e - p a r a l l e l lamiith small amplitude, to ripple lamiith l a r g e r amplitude showing slight i o n t h a t has been reworked by orgaBedwell Harbour, North Pender I s l a n d .  The upper h a l f of the specimen contains convolute lamination. Laminae i n v o l v e d i n the l o wer \ inch of the convolution are p a r a l l e l to e a c h O t h e r , but above t h i s t h e l a m i n a e show cross lamination, V e s u v i u s Bay., Salt Spring Island.  C o n v o l u t e l a m i n a t i o n on a b e d d i n g p l a n e . The p e n c i l l i e s on the u p p e r b e d d i n g p l a n e surf a c e o f a s a n d s t o n e bed t h a t d i p s s t e e p l y t o ward the bottom of the photograph. Note s i m i l a r i t y of convolute lamination to linguoid ripples, V e s u v i u s Bay, Salt Spring Island.  O r g a n i c ..borings i n s h a l e a t h i g h a n g l e lamination. V e s u v i u s Bay, Salt Spring  to the Island.  O r g a n i c b o r i n g s on t h e s o l e o f a s a n d s t o n e bed obliterate questionable loaded f l u t e casts (a). Note a narrow groove c a s t ( i n d i c a t e d by arrows). Current d i r e c t i o n from lower right t o u p p e r l e f t as i n d i c a t e d by the f l u t e and groove casts. V e s u v i u s Bay, Salt Spring Island.  L o a d e d f l u t e c a s t (a) and a w i d e g r o o v e cast (b). Current d i r e c t i o n i s from lower right to u p p e r l e f t . V e s u v i u s Bay, Salt Spring Island.  72  presence of convoluted and current ripple lamination i n the same bed suggests either: (1) the cohesiveness of the grains of the bottom sediments was not uniform during t h e i r deposition, resulting i n the formation of both current ripple and convoluted l a mination; or (2) that current ripple lamination formed f i r s t i n cohesionless sediments, then l o c a l l y the cohesion increased, and the overlying current deformed the ripple lamination convolute into/1 lamination (this phenomenon of increase i n cohesion was called the "Hjulstrbm effect" by Sanders (1963, p.178). Both assumptious seem v a l i d , since i t was observed that there are two types of convolute lamination present.  The  f i r s t type, i n which the convoluted laminae are p a r a l l e l to each other ( f i g . 5 5 , the laminae of the basal g inch of convolute lamination are p a r a l l e l to each other), ind- - ?  >  tes that these laminae were o r i g i n a l l y plane p a r a l l e l and not current ripple laminae, and were deformed due to the shear applied by the overpassing current on cohesive sediments.  In the second type, convolution was developed  after r i p p l i n g since ripple cross lamination i s s t i l l preserved i n the convolute lamination ( f i g . 5 4 ) • Convolute lamination could not be observed i n three dimensions, except f o r one bed where the upper bedding  73  plane i s exposed ( f i g . 5 6 ) . From this picture it, seems that the o r i g i n a l structure before convolution was a be:l of linguoid ripples* Regarding the o r i g i n cf convolute lamination, Keener (1953,  p.  1057;  attributed their formation to " i n t e n s i f i -  cation of ripple mark by hydrodynamic pressure combined with loading i n the troughs' : Ten Raaf 1  1962, ,;  (1956,  i n McBride  p. 52) modified this mechanism s l i g h t l y and proposed  that the action of accelerated deposition i n troughs o i  1  probable incipient ripple marks combined with the expulsion of water through the crests was the cause". (1963  and  1965)  and Walker  (1965),  Sanders  pointed out the impor-  tance of cohesiveness of the bottom sediments i n t h e i r formation.  Other workers f e e l they may be post-depositio-  nal, deformational structures, formed by "Lateral i n t r a s t r a t a l flow of l i q u i f i e d beds" (Williams,  I960),  cr b y  "creep when sedimentation took place on a slope.'' (Holland,  1959).  d. Interturbidite Division (DE-division) Because i t was d i f f i c u l t to differentiate between the upper d i v i s i o n of plane-parallel lamination (D-division), and the p e l i t i c d i v i s i o n (E-division) i n the f i e l d , the author has called the laminated shale overlying the sandy part of the t u r b i d i t e unit the "interturbidite  Ik  d i v i s i o n " (Walker,, 1967) , (figs. 5, 15, and 3 6 ) .  But the  reader should not think of them as e n t i r e l y non-turbidite i n o r i g i n , since they show some grading from s i l t to clay size, suggesting deposition from a current suspended load (Sanders 196$,  and Walker, 1 9 6 $ ) .  The main structure i n this d i v i s i o n i s plane-parallel domination.  This lamination was believed by Walker (1965,  p. 19) to be formed by the alternation of  coarse-grained  and finer-grained laminae. ' Occasional laminae of l i g h t colored, very fine-grained sandstone were found to contain foreset lamination. This d i v i s i o n varies i n thickness from a f r a c t i o n of an inch to 33 inches and averages about 2.$ inches. : Figures 16,. 17, and 18 show the cumulative frequency of the thicknesses of 727 i n t e r t u r b i d i t e divisions measured i n Vesuvius Bay section of Salt Spring Island, and the Bedwell Harbour section of North Pender Island.  These  also show log normal d i s t r i b u t i o n . The shale of t h i s d i v i s i o n contains accasional animal burrows, oriented i n various directions. Some are parall e l to the bedding, others are inclined at different angles to the bedding plane,, (figs. 36 and  $7).  75  B.  Sole  Marks.  These stone for  a r e marks  and s i l t s t o n e  determining been  drag  and s c o u r i n g  formed  Many o f them  side  have  as f i l l i n g s  of depressions  of currents  and t h e i r  of  sand-  been  used-  since  they  caused  loads  by the  along  a  bottom. Dzulynski  sole  beds.  on t h e bottom  directions of paleocurrents  have  muddy  present  marks  into a.  (1962,  and Sanders  the following  Marks  made  deposited  Organic.tracks  2.  Structures mud  b.  .Current ge  Scour  marks  Toolmarks: contact the  which  of  carrying the bed  i n t h e mud  arrived.  by the  carried  (flutecasts,  the  passasedi-  channels,  and  marks). marks which  o f some  bottom  bounce  o r slump  the covering bed:  frondescent 2.  by"creep  the current  made  of the current  ment, f o r m i n g 1.  made  of the cur-  burrows.-  f o rt h e -covering  marks  classified  t h e c o v e r i n g bed::  and  before  material  have  to the a r r i v a l  1i.  the  6l)  groups:  prior  rent- w h i c h  p.  (e.g.  marks).  object groove  a r e made  by the  (the t o o l ) and casts and  76  c.  Marks and  made  at the interface  covering bed a f t e r  between  t h e mud  deposition of  cover-  ing bed. 1.  Organic  2.  S t r u c t u r e s made  by deformation  flowage,  o r slumping  ment  tracks  and  creep,  mass.  Load  burrows.  casts f a l l  due t o  of the sedii n this  category.  Relatively posed that  i n the study belong  above  It marks,  beds  are well  ex-  a l l the different  and t h i r d  major  have  been  observed  that  c u r r e n t marks  groups  marks  of the  i n t h e Cedar  Formation. observed  especially  flute  channels)  beds  thicker  of the type  only  than  and a  made  bed, are present  are  not restricted loaded  flute  post-depositional  c a s t s and groove  are present  ing  cross  o f sandstone but almost  t o t h e second  was  casional  rows  area,  c l a s s i f i c a t i o n  District  stone  few soles  a  foot  after i n beds  only  origin.  and  on t h e s o l e s o f half.  of variable beds.  ( f i g . 58)  tool  casts with oc-  Organic  the deposition of the  t o thick  casts  (scour  sandbur-  cover-  t h i c k n e s s and Burrows  clearly  which  indicate  their  77  a. These bidity  are  f i l l i n g s  current  protrude  from  i n  parallel  current  end  from  (Bouma,  soles, These and On  fine,  a  bed  nable  flute  section, rowing; the  with  an  bed  At  turcasts long  the  d i -  up-  protrudes  fur-  direction;  flute  bigger  v/as - o b s e r v e d  casts,  Bay  were  five  inch  casts  on  casts  a  observed by  p a r a l l e l i s m to $8).  i n  and  a  groove  49).  are  shows  three  feet  Questio-  Vesuvius and  half.  casts,  marks  ( f i g . 59). the  a  ( f i g .  which  of  Here,  length,  flute  bounce cast  the  their  i n  half,  loading a  on  foot  the  sole  section,  modified  ( f i g .  and  flute  a  i n  Island.  inches  and  the  only  Pender  containing  groove  slightly  sole,  North  than  extensively  same  found  less  the  show  are  are  i n Vesuvius  they  a  the  down-current  thicker than  c l o s e l y spaced  thick  with  and  were  same  loading,  of  observed  of  some  the  by  flute  direction.  casts  averaging  A  oblong  i s narrower  i n  width  found.  The  beds  casts  sole  mud.  made  138).  were  these  also  on  than  Harbour  flute  the  cast  Bedwell  and  marksj  are  current  flute  beds  have  the  flute  p.  scour  they  developed  of  two  to  of  Casts  underlying  sole;  sole  1962,  section only  the  the  Well  the  the  mension  ther  Flute  Bay  organic  cast  bur-  present  73  b. Frondescent_Marks ? Scour marks that are f i l l e d with coarse grained sandstone containing scattered granules, have been observed on the sole of a thick sandstone bed i n the uppermost part of the Vesuvius Bay section of Salt Spring Island; they are associated with and p a r t i a l l y obliterate gigantic groove, casts, indicating t h e i r formation subsequent to the formation of the groove casts ( f i g i 6 0 ) . They have a dendritic lobate form'j the average length of the i n d i v i dual lobe i s four inches and average width i s about two inches*  The down-currertt end of each lobe protrudes from  the sole more than the up-current end ( f i g . 6 l ) i Scour marks of a similar nature have been produced experimentally, and called frondescent marks by Dzulynski and Walton  (I962j  p. 291, plate XXb and XXIa), and  Dzulynski (1965, p» 198j f i g * 7)»  Similar marks have  been called "cabbage leaf cast" by Ten Haaf (1959), and "fondescent furrow f l u t e casting" by Mclver (1961), i n Potter and Pettijohn (1962, p. 126-127, f i g . 5-10)-. Scour marks that cut the underlying lamination i n shale have been observed i n one l o c a l i t y i n Vesuvius Bay in Salt Spring Island. They are f i l l e d with coarsegrained sandstone and scattered granules, and a few of them show some loading, ( f i g s . 62 and 6 3 ) . Due to  79  Fig.  6 0 :  Fronde-scent marks (a) p a r t i a l l y obliterate groove c a s t s (b) on t h e s o l e o f a t h i c k sands t o n e ' b e d t h a t d i p s s t e e p l y a w a y f om t h e o b server. Current d i r e c t i o n from lower right to upper l e f t . The s c a l e i s 3 f e e t l o n g . Vesuvius Bay, Salt S p r i n g Island. Fig.  6 1 :  A close-up o f t h e f r o n d e s c e n t marks o f t h e same b e d i n f i g . 6 0 . Current direction from right t o l e f t . Scale i s about 8 inches l o n g . Vesuvius Bay, Salt Spring Island. Fig.  6 2 :  Scour marks on the base o f a t h i c k sandstone bed u n d e r l a i n by a t h i n bed o f s h a l e . Vesuvius Bay, Salt Spring Island, Fig;  6 3 :  L o a d e d s c o u r m a r k s o n t h e b a s e o f t h e same sandstone bed as i n F i g . 6 2 . Vesuvius Bay, Salt Spring Island. Fig.  6k: A s o l e o f a t h i c k s a n d s t o n e b e d (same a s i n f i g s . 6 0 and 6 1 ) , showing a t l e a s t 3 generat i o n s o f g r o o v e c a s t s ; some show c h a n g e i n direction. Current from lower r i g h t t o upper left (measured from the frondescent marks to t h e l e f t o f these groove c a s t s ) . Vesuvius Bay, S a l t S p r i n g I s l a n d .  80  incomplete they  exposures,  are flute  casts  i t was or  long  grooves  carried l e l  other  reveal marks  only  such  current  foot  very  along  half.  the line  grained  sand  bottom  The g r o o v e s The g r o o v e  of current,  casts  some  object  are paral-  casts  them-  but presence  provide  information  of on  i n beds  I n one  l o c a l i t y  ( f i g . 49),  they are  of an  i n  of a fraction exposed  and appear  ofa traction  below  sandstone  casts  beds  sizes  and o r i e n t a t i o n s ,  about  50  ( f i g . 64  to the northwest  formed  width,  by  along  coarse  the  carpet. o f t h e Cedar  Formation  at  a n d 65).  The  District  Vesuvius  three  a l l having  genera-  different same b e d  has two generations  i n t e r s e c t i n g a t an angle  than  strikingly  has at l e a s t  on i t s s o l e ,  thicker  inch  o r pushed  the DeCourcy  bed o f sandstone  are  been  a t t h e base  of groove  casts  t o have  dragged  tions  feet  sole,  or granules  just  a thick  groove  by  of  observed  t h e uppermost  Formation,  mud  up  are also  t h e whole  spaced,  In  current.  direction.  a matter  closely  Bay,  i n the underlying  as f l u t e  casts  narrow,  muddy  by the f i l l i n g  direction.  and a  extend  whether  Casts  a r e formed  i n a turbidity  Groove a  scoured  to the current  selves  the  structures  to t e l l  channels.  c.Groove These  not possible  varying  from  of 11 t o  *  31  30  degrees  ( f i g . 66).  narrow  and  higher  above  (figs.  64,  groove  casts  The posed drag  the sole  65,  surface  and 6 6 ) .  show  shape  a  the main  they  tree,  being  formed  from  twigs  casts  were  obviously  none  of these The  groove  wood  tools  height  and s t r u c t u r e  (1959,  p.534)  carrying  considered  their  turbulent  larger  objects  result  of inertia,  and of  concluded grains  dominant  i s  the  formed  branch  of  superimby the  or trunk  with  casts  ridges  tools,  fragments, the  which  within  a result of  but rather travel  saltation)".  the  current p.63)  the current  caused  paths  i n various  "are the result of mechanism  l e d Hsu  "sediment-  i n linear  the bottom  of  (1962,  and Sanders,  but  casts.  i n general  flow  of  narrower  smaller  or shale  found  not as  ....  i n the traction a c t i v i t y  with  The  by  laminar  to strike they  group  the superimposed  formed  Dzulynski  (tools),  that  cast,  of groove  eddies  ridges  c o n t i n u i t y , and u n i f o r m i t y  formation  loaden  superimposed  been  the main  been  to postulate  the tools.  have  fragments,  straightness,  raised  casts  i n the trunk.  have  very and  of the latter  may  made  as pebbles,  are wider  show  groove  which  such  are  i n d i r e c t i o n ( f i g . 65).  of the wide  suggests  grooves  others and  Some  change  of a water-logged  groove  of these  ( f i g . 65),  straight  ridges  Some  as  a  ways",  transportation  ( i nt h i s  case  the  S2 Fig. 6 $ :  Groove casts of different shapes and sizes. Note the change i n direction of the wide grooves with the superimposed ridges (a). Same bed as i n f i g . 6 4 . Hammer indicated by an arrow. Vesuvius Bay, Salt Spring Island*  Fig. 6 6 i ; Two generations of intersecting groove casts with superimposed ridges. Vesuvius Bay, Salt Spring Island. Fig. 6 7 : , Clasts of laminated, fine-grained sandstone (at both ends of pencil) embedded i n coarsegrained, thick sandstone bed. Vesuvius Bay, Salt Spring Island. Fi  g i  68:  Fig. 6 9 :  Fig. 70:  Deformed clast of laminated, fine-grained sandstone embedded i n thick bed of coarse-grained sandstone. Vesuvius Bay, Salt Spring Island. Clast of fine-grained, laminated sandstone showing recumbent folding, embedded i n a thick bed of coarse-grained sandstone. Vesuvius Bay, Salt Spring Island. Thinbeds of sandstone and t h e i r interlayered shale (at head of the hammer) involved i n softsediment deformation and engulfed by the overlying thick sandstone bed. Note how these thin beds are s t i l l connected with the underlying .undisturbed beds. Vesuvius Bay, Salt Spring Island.  Fi3-^9  F-,3-70  $3  The single by  v a r i a t i o n i n d i r e c t i o n of groove  sole  (e.g.f i g s .  (1959,  Ten Haaf  64  a n d 65)  i n Dzulynski  has been  t o change  but  to the criss-crossing of lobate  (1962, p.91)  a  1962,  i n the d i r e c t i o n of the entire  and Sanders  on  attributed  and Sanders,  not  Dzulynski  casts  fronts  p.86)  current,  of the  suggested  that  current. this  change  i n d i r e c t i o n o f t h e t o o l marks  i s the result  of  change  i n d i r e c t i o n o f movement w i t h i n  the t r a c t i o n  carpet.  d. These as  "sole  what  structures  markings,  less  objects  behind  a  ends." only  observed  about  groove  t o be  inch  direction,  long,  parallel  They  which  D i s t r i c t  Pender  since  to the  were  fades  they  sandstone ( f i g .  leaving at  casts  49)...  both  were  They a r e inch  flute  on both  wide,  and  of the current  equally  produced  bed i n Bedwell  f r a c t i o n o f an  the track fade  such  some-  current  out gradually  Formation  of a  and  presumably  t o the associated  indicate  i n length  and rebounding,  Island  and a  cm  parallel  the bottom  (1962, p.135)  b y Bouma  to 5  grooves  on t h e s o l e  i n North  one  casts.  short  grazing  shallow  up  running  I n the Cedar  Harbour  tend  These  Casts  are defined  varying  i n width,  direction. by  Bounce  and  groove but not  ends. •  i t s  $4-  e. O r g a n i c  Borings  and B u r r o w s  B e s i d e t h e b o r i n g s and b u r r o w s t h a t a r e found t o protrude  i n t o s h a l e and t h e c a l c a r e o u s c o n c r e t i o n s , t h e r e  a r e a l s o some s a n d s t o n e b e d s w i t h o r g a n i c b o r i n g s a n d b u r r o w s on t h e i r  s o l e s ( f i g . 58)»  burrows probably  o r i g i n a t e d a f t e r t h e f o r m a t i o n and l o a d -  i n g o f t h e s c o u r marks i s suggested  T h a t t h e s e b o r i n g s and  by the f a c t t h a t , i n  some c a s e s , t h e y p a r t i a l l y o b l i t e r a t e s c o u r marks on t h e same s o l e  (fig'.  58).  C. . S o f t - S e d i m e n t Structures slumping  Vesuvius  Bedding.  (slump o v e r f o l d s ) t h a t a r e t h e r e s u l t o f  on S a t u r n a  s e c t i o n on p e b b l y An  Disturbed  I s l a n d , were d i s c u s s e d i n a p r e v i o u s  mudstone.  i n t e r v a l o f about 330 f o o t i n t h e middle  B a y s e c t i o n on S a l t S p r i n g I s l a n d , i s c h a r a c t e r -  i z e d by abundant t h i c k beds o f sandstone thick). for  of the  (up t o 7 f e e t  These b e d s a r e i n t e r n a l l y s t r u c t u r l e s s  except  "rude g r a i n s i z e g r a d i n g f r o m g r a n u l e s and c o a r s e -  grained  sand, a t t h e b o t t o m t o medium and f i n e - g r a i n e d sand  a t t h e top.-.  Interbedded  ner bedded, l a m i n a t e d shale  w i t h t h e s e t h i c k beds,' a r e t h i n -  sandstone  ( B - and C - d i v i s i o n ) , a n d  (DE-division of interturbidite). These t h i c k beds o f s a n d s t o n e a l m o s t  always  enclose  6*5  Fig.  71: Clasts wing sl bed o f Bay, Sa  Fig.  of fine-grained, laminated ight deformation, enclosed coarse-grained sandstone. lt Spring Island.  72: Clasts of showing as thick bed crusting b Island.  Fig.  s a n d s t o n e shoi n a thick Vesuvius  f i n e - g r a i n e d sandstone and shale ymetrical folding, enclosed i n a o f s a n d s t o n e . W h i t e o b j e c t s a r e enarnacles. Vesuvius Bay, S a l t Spring  73: Recumbent f o l d i n g i n sandstone and shale c l a s t s which are enclosed i n a t h i c k bed of sandstone. Vesuvius. Bay, Salt Spring I s l a n d .  Fig.  74: C l a s t s o f f i n e - g r a i n e d sandstone beds enclosed i n c o a r s e - g r a i n e d t h i c k sandstone bed. T h e s e c l a s t s show c o m p l e x d e f o r m a t i o n . Beds dip steeply to the l e f t . Vesuvius Bay, Salt Spring Island.  Fig.  75: Sandstone Island.  Fig.  dike  cutting  through  shale.  Mayne  76: Very t h i n discontinuous sandstone t h r o u g h s h a l e . Mayne I s l a n d ,  dike  cutting  86  clasts and pieces of beds composed of coarse-grained sandstone, laminated fine to medium-grained sandstone, or shale, or a combination.of two or three of them. These clasts occur either i n the form of small, angular chips a few inches i n length ( f i g . 6 ? ) , or large, gently or t i g h t l y folded clasts ranging i n length from a few feet (figs. 2 7 , 6 8 , and 6 9 ) , to several feet ( f i g . 2 6 ) . Some of these deformed layers can be traced l a t e r a l l y and observed to connect with the underlying undisturbed beds ( f i g . 7 0 ) , This kind of bedding and the associated enclosed clasts are also present intermittently i n the upper part of the Vesuvius Bay section* These enclosed clasts are fragments of beds that seem to have been stripped from o r i g i n a l l y coherent layers. They represent fragments of beds belonging to the B, C, and DE divisions.  Beds underlying the thick sandstone  beds are composed essentially of B, C, and DE divisions. • These clasts exhibit a wide range of structures. Some are gently folded (figs. 27 and 7 1 ) , others show a symetrical folding ( f i g . 7 2 ) , the majority show recumbent folding ( f i g s . 2 6 , 6 9 , and 7 3 ) , and s t i l l others are thrown into a complex pattern of folding ( f i g . 7 4 ) . The l a s t type of folding involves clasts that can be traced l a t e r a l l y into the underlying undisturbed beds.  37  The disturbed layers are always seen i n only.two dimensions.  The strike of t h e i r fold axes appears to •  have a general preferred orientation of northwest- ,  t  southeast, but precise measurement i s not possible, be- • cause of lack of three dimensional outcrops.  By using  graded bedding and the v e r t i c a l succession of the d i f ferent t u r b i d i t e d i v i s i o n s , the author v/as able to determine top-bottom relationships i n the disturbed, layers and thus could d i f f e r e n t i a t e between a n t i c l i n e s and .synclines i n tne case df recumbent folds ( f i g . 2 6 ) .  In the case of  thin-bedded, laminated,- complexly folded c l a s t s , howeyer, i t was not possible to determine top-bottom relationships, hence i t v/as not possible to determine'whether the: folds are synclines or a n t i c l i n e s . Certain l i m i t a t i o n s can be placed on 'the processes which deformed these beds.  Since the beds overlying and  underlying the deformed beds are undisturbed, t h i s deformation must have been syndepositional.  The thick sand-  stone host beds were soft enough to engulf the underlying thinner sandstone and shale beds; the l a t t e r must have been also soft, but they were cohesive enough to be plast i c a l l y deformed and not dispersed into a  cohesionless  mass!''  The fact that some deformed clasts, in. the thick  C58"  sandstone beds, are s t i l l connected to the underlying undeformed beds suggests that they were deformed and engulfed without l a t e r a l transport during the emplacement of the overlying sand.  Other clasts i n the thick sand-  stone beds, which are disconnected from the underlying undeformed beds , may or may have not undergone appreciable l a t e r a l transport. From the above i t can be concluded that the enclosed cxasts were o r i g i n a l l y parts of soft, undisturbed, s t r a t i f i e d beds on the sea bottom.  They subsequently  became disturbed and broken up during passage of a current carrying a dense slurry of sand which engulfed them. This slurry was later deposited as a thick sand bed. Dzulynski and Radomski (1966)'experimentally reproduced nearly i d e n t i c a l structures by introducing a heavcy suspension into a flume tank whose bottom was with s t r a t i f i e d soft  covered  layers. The bottom layers were  interlayered clay beds, deposited by normal s e t t l i n g i n the flume, and beds of mixed plaster of Paris and coal dust deposited t. an a r t i f i c i a l t u r b i d i t y current. The introduced heavey suspension was composed of a mixture of plaster of Paris, cement, sand, and occasionally small pebbles dispersed i n water.  'When this heavey suspension  $9  Fig.  77:  Fig.  78:  Fig.  79:  Thick sandstone dike c u t t i n g shale Dodd N a r r o w s , V a n c o u v e r I s l a n d .  sequence.  B r a n c h i n g s a n d s t o n e d i k e (hammer a t p o i n t o f b r a n c h i n g ) . Dodd N a r r o w s , V a n c o u v e r I s l a n d . Sandstone d i k e c u t t i n g s h a l e . Note c o n t o r t e d lamination w i t h i n the dike. Dodd N a r r o w s , Vancouver I s l a n d .  F i g . 80: ;  E x o t i c b l o c k o f s a n d s t o n e embedded i n s h a l e , Note t h e b e n d i n g o f s h a l e l a m i n a t i o n b e l o w t h e b l o c k , and t h e a b r u p t t e r m i n a t i o n o f l a m i n a e a g a i n s t l e f t s i d e o f t h e b l o c k . Dodd Narrows, Vancouver I s l a n d . F i g . 81: E x o t i c b l o c k o f s a n d s t o n e embedded i n s h a l e , A l s o note the bending of shale l a m i n a t i o n a r o u n d t h e b l o c k , and t h e a b s e n c e o f o t h e r e x o t i c m a t e r i a l s * Dodd N a r r o w s , V a n c o u v e r Island. F i g . 82'  Deformed, l a m i n a t e d sandstone c l a s t s enclosed i n s h a l e . N o t e fragmented sandstone bed a b o v e t h e c l a s t s . Mayne I s l a n d .  90  was  allowed  ments  to  i n the  flume,  fied  deposits  into  clasts  the  heavey  sand  clasts  to  to  The  what' h a v e  authors  tion  of  to  lar  mechanism;  horizontal flow  of  over  soft,  D.  a  the  called  " b a l l -  leads  and  the  previously  outcrop Dodd feet  between  s t r a t i up  wide  a  of  Once  "thick"  range  of  1966;  these  deformed  overfolds", structures, f o r the  and  led  forma-  author a  of  the  to  heavey  layers. a  suspension  This  of area  the of  could  traction  only  simi-  upon involve  carpet  moving  beds.  Features  i n two  Cedar  l o c a l i t i e s  District  Vancouver  formation  Vesuvius  postulate a  turbidite  found  experimentally  i n the  Miscellaneous  area  Narrows  these  observed  deposited  d i k e s were  1010  "slump  current with  Sandstone  upper  some  mechanism  of  sedimentary  turbidity  the  as  Radomski,  a  present  Dikes  In  a  pillow"  those  i . e . impact  soft  the  of  sedi-  suspension.  and  similarity  Sandstone  throughout tion.  the  structures  section  ( D z u l y n s k i and  the  broken  settled  assumed  similarity  of  were  heavey  bottom  structures.  Likewise,  Bay  beds  completely clasts  been  and  the  p o s t u l a t e such  these  produced  had  patterns 5).  stratified  latter  into  enclosed  "pseudo-nodules", the  The  engulfed  the  soft,  considerable deformation  suspension  deformational 1  over t h e  occured.  and  layer,  photos:  flow  Forma-  Island,  i s exposed,  where  sandstone  91  dikes quite commonly cut a shale sequence containing a few thick sandstone beds ( f i g . 14).  Also on Mayne Island,  where the upper 200 feet of the formation are exposed on the- south coast 3 the lower 50 to 70 feet of this section contains occasional sandstone dikes cutting shale beds ( f i g . 75).  Thus i n both l o c a l i t i e s , the sections cut by  dikes are mainly shale with a few thick sandstone interbeds . The sandstone dikes are tabular bodies, ranging i n thickness from a fraction of an inch ( f i g . 76) to about 3 feet ( f i g . 77)*  In general they have sharp walls, and  they may cut the host beds either at right angles, high angles, or very low angles.  Their shapes vary from  straight, regular, thick dikes ( f i g . 77), thin dikes ( f i g . 14).  to irregular  Most of the dikes can be traced  for only r e l a t i v e l y short distances, either because they are discontinuous or because of lack of exposures.  In  one case ( f i g . 2 3 ) , a sandstone dike was observed to extend downward from a thick sandstone bed f o r a distance of a foot and a half through laminated shale before i t disappears into the shale bedding plane.  One of the  thick dikes i s observed to branch into an offshot that runs at a low angle across the bedding planes of the host rocks ( f i g . 78)•  92 The thick dikes seem to be structureless as observed by the nacked eye i n the f i e l d .  Some of the thin dikes  show d i s t i n c t lamination, which i s commonly wavey and occasionally contorted, roughly resembling current ripple and convolute lamination ( f i g . 79).  Whenever  the host rocks  are faulted, the associated sandstone dikes are also faulted, indicating that the sand injection took place before f a u l t i n g . In the same shale intervals where the sandstone dikes are present, are clasts and blocks of rocks, either of lithology foreign to the host rocks ( f i g . SO and S i ) , or of the same lithology as some beds overlying the host rocks ( f i g . 82).  Blocks of the former type are observed  only i n the Dodd Narrows area on Vancouver Island. Shalelamination overlying and. underlying these blocks curves around the blocks ( f i g . S i ) , while l a t e r a l l y adjacent lamination ends abruptly against steep sides of the blocks ( f i g . SO).  Because only two or three of these blocks,  which are widely spaced i n the- horizontal direction, have been observed within this shale i n t e r v a l , and because of the fact that they are surrounded by w e l l laminated, undisturbed shale, with no other exotic clasts or pebbles and sand i n the v i c i n i t y , the p o s s i b i l i t y of their i n t r o duction as a mass slump o r slide seems improbable, since  93 one would expect to find a mixture of elastics of d i f f e r ent sizes and shapes, as i n a pebbly mudstone.  Their  origin i s problematical, but two p o s s i b i l i t i e s exist: (1) They may represent isolated sand-filled channels. The wedge-like shape of some blocks ( f i g . 81) and the fact that adjacent shale laminae terminate abruptly against the sandstone ( f i g . 80) tend to support t h i s  interpretation.  But the overall shape of other blocks (fig.. 80) do not i n any way resemble channels. (2) They may represent blocks of sandstone transported individually from elsewhere; the fact that the blocks are not folded would indicate their introduction as highly consolidate! ., or cemented, masses, 1  otherwise they would have been deformed.  One p o s s i b i l i t y  i s that the blocks were detached from shoreline c l i f f s or sea bottom outcrops by gravity and/or seismic shocks and s l i d or r o l l e d down into the basin of shale deposition, truncating some laminae during f i n a l emplacement. Subsequent b u r i a l and compaction around the coherent blocks would, produce the curving laminae above and below ( f i g . 8l).  Although the exact origin remains unclear, the  author i s inclined to favor the second p o s s i b i l i t y , or some variant of i t . Clasts of t h i s l a t t e r type occur i n one l o c a l i t y as deformed sandstone clasts, which show no preferred  9h  orientation, and are embedded i n a shale host rock ( f i g . 82).  Just above this shale ami i t s enclosed clasts i s a  bed of sandstone with characteristics similar to those of the underlying sandstone c l a s t s .  This sandstone bed i s  fragmented just above the sandstone c l a s t s , as i f these clasts were once part of the sandstone bed.  This kind of  feature seems to have been formed when a sand bed was deposited on a soft muddy bottom; l a t e r t h i s bed may have been fragmented into clasts which were then folded and sank into the underlying mud.  The disruption of t h i s sand  bed into sand clasts could be accounted for by some kind of a shock (e.g.. an earthquake). The formation of sandstone dikes has been accounted for as a result of "earthquake shock, momentary l i q u i f i cation of watersaturated sand, and i n j e c t i o n into fissures opened by the shock.  The driving force i s the pressure of  the overlying strata.", (Potter and PettiJohn, 1963, p. 165). From the above, i t could be inferred that during deposition of the shale sequence with occasional sandstone beds, the site of deposition and adjacent areas were tech n i c a l l y active and suffered a period of intermittent earthquakes.  These  caused  l i q u i f i c a t i o n of the soft sand  and i t s injection into fissures opened i n the surrounding  S e r i a l Hoo j - Specimen  2  1  Wo  0  Quartz  V103C  Vll  36 5  27*5  e  3  V26 45 o 8  4  5  6  V30  V34  V39  0  33*7  26  35o5  0  8  io 1  9  VSA3  VSC6  VS18  P34  2 8  44 a  39o2  2 9 o 7  0  o  7  12  14  16  15  17  18  19  21  20-  22  23  2 4  25  PI 5  44o3  pi'25  5213  15  P B 2 4  PB4  PA?  P B 1 0  PA12  PB13  PC  28,4  5 0 o 0  48 8  5 7 o 4  3 9 . 0  51.0  45.2  17.7  10.0  5 . 2  0  26 ^taCnvrfv-vmTiTirra=  r  S?  Sa  4 3 . 3  49.0  Sb 42.2  I  M4  Cl  C6  3 1 . 4  34.7  3 6 . 3  4 . 7  9 . 0  3 5 . 5  i  1 •  J  K=»feldspar  9c2  7 * 0  4 c 9 7 o l  4 o 7  Plagioclase  6o5  4o0  Mica  9o2  5o3  l o d  3o8  4o9  0o7  V o l c a n i c rock fragments  0  Sedimentary r o c k fragments Metam©rphic r o c k fragments P o l y c r y s t a llin« quarts Chert cement  e  2  C D  0  o  2  1*7  2»8  0o2  0 2  i  0  o o  o  0 4  0 2  0o3  24o6  49o6  34*5  o  0.7  c=e=  4o 5  2 i o 6  13 0 6  4o2  1P3  4 . 6  o  o4  5o3  2  O  '  j  0  4o4  4 o 3  4 . 0  0o7  ijo  4.7  0.2  0.9  5 . 5  8.0  8 . 3  14.7  5 . 8  10.0  6.0  7 . 3  0.8  0.7  1.0  2 i l  «—  2.1  4 o 8  0o7  1 P 7  i  1 t  1I2-  0 3 o  3o3  0o5  7o7  l o d  5 . 0  4o4  0 o 9  0o3  2 J 7  2 7  26o8  4o0  4 « 6  0.4  <L«2  1  0 ;  0  Siliceous cement  =>  7o2  2 . 0  3 . 4  5.3  6P3  27o5  l 6 o l  4.0  as  2 7 c 7  13 *  9  8  0  1 4 o l  3  4 6 d 2  1*6  2 0  1*8  l o 2  3 . 8  2 o 9  0.6  2o7  l-o2  2 ©2  2.1  2o7  Others  3 » 6  4c2  3 o 2  2.0  l o 7  1O6  1  2  0o3  4 o 6  0o6  0  3  o4  o  Table 2s • Composition ©f t h e Cedar D i s t r i c t sandst@nes  5il  C r  18 5 Qn* t  1  e  q  u  a  r  t  z  0 8  2.3  2  -  0.3  0.2  0.7  4.7  6 . 6  0.2  0 . 8  0.3  CD  0 . 8  1.0  1.6  6.0  ex»  0.4  0.3  ea  0  0.2  CO  0.9  0.6  0.3  0 . 4  0.4  0.8  1.2  0.6  0.8  G>  1.0  0.3  1 . 3  1.3  3 . 6  4 . 0  2.6  1 2 . 8  2 3 . 3  1 8 . 5  26o2  1 . 9  ~ 1 . 8  2 . 5  13  o3  -  =  ens  0.8  1.4  -  0 2 o  1.5  0 . 5  2.9  0.7  0.3  1 2 . 3  8 . 5  2 9 . 2  7.4  0.9  1 4 . 9  •-  6 4 0  5 6 . 0  1 . 8  5.0  6 . 6  7.6  9 . 6  0 . 4  2 , 4  2 . 8  1 . 7  1.2  1.3  2 . 2  2 • 2  3.2  6 . 0  8  r  *  4.7  e  !L  2.2  2 4 . 3  -  42.1 »  2 5 . 4  4.0  6 . 3  1.3  0.7  2.1  2.0  2.0  I 0 6  1.0  3 . 6  3.7  2 . 2  2 3 . 1  2 . 2  1.7 1 , 8  I  1  Unkn@wn  0  2.9  0.4  0.4  i 0  12.1  .  2 1 . 0 I j  1 8 . 6  1.3  ( 2 9 o 7  3 3 o9  1 5 . 6  1.6  •=  i  6.1  5 . 6  0.8  0.5  7.0  1.4  3 . 0  J  1  Matrix  12.4  9 . 3  4.7  9 c 5  1  t  1O6  0o4  7.7  !  0 2 0  8 . 1 8 . 0  5 . 1  I 2 J 5  11 0 0  i  3 J 3  =,  o  20  2  l o 2  0 o 8  4c3  o  17.1  0 2  —  o  3o4  l o 4  8„0  l o 5  l o 4  2  2o9  6 o l  5 d  o  =  9o3  20 6  ll»5  2 0 , 5  Chlorite  Calcite  1 2 . 6  0  ,• j  ^ a r t s i t e i n c l a s s i f i c a t i o n triangles  —_  O  r»  1.8  1.6 2.6  - 1 . 2  2 . 5  .—4L  1  J  96  coherent mud. These shocks may have also resulted i n the disruption of some thin beds of soft but cohesive sand into clasts that sank into the underlying soft mud, forming what are observed now as sandstone clasts embedded i n shale host rock with a r e l i c of the mother" sandstone ,:  bed underlying them ( f i g . $ 2 ) . At the same time, i t i s possible that these shocks affected the shore l i n e or sea bottom outcrops, resulting i n the detachment of some sandstone blocks which s l i d or r o l l e d \own across the basin slope as individual blocks.  Such downslope trans-  portation may have been intermittent, requiring a series of such shocks. 7. PETROGRAPHY OF THE SANDSTONE The composition of twenty s i x sandstone samples was determined quantitatively by the method of point-count. Twelve of these samples were stained with sodium c o b a l t i n i t r i t e f o r potash feldspar determination. Table 2 shows the results of these determinations. A. Quartz: This i s the most abundant mineral component of the Cedar D i s t r i c t sandstone, varying from 26.0 to 57.4 percent and averaging 39.8 percent. No attempt was made to  97 Fig*  83: Photomicrograph showing quartz grain by the c a l c fractures ( i n d i c a t e d by n i c o l s . Vesuvius Bay, S a (V39).  Fig.-  the replacement of i t e cement a l o n g arrows). Crossed lt Spring Island  a  84: Photomicrograph showing the replacement of a q u a r t z g r a i n (Q, i n d i c a t e d b y a r r o w s ) and a f e l d s p a r g r a i n (F) by t h e c l a y - s i z e matrix.' Crossed n i c o l s . V e s u v i u s Bay, S a l t S p r i n g Island. (VS18).  Fig.'85: Photomicrograph showing the replacement of a f e l d s p a r grain (F, i n d i c a t e d by arrows) by t h e c a l c i t e cement a l o n g f r a c t u r e s . Crossed n i c o l s . • Vesuvius Bay, S a l t S p r i n g Island. (V39).  F.3- 8 3  F»3 85"  96"  c l a s s i f y tho quartz into the different types based on the external morphology, internal features, and extinction characteristics.  The  work by Blatt and Christie (1963)  has cast doubt on using the above mentioned properties for the purpose of r e l a t i n g the quartz to i t s parent rocks. Size of the quartz grains varies from fine s i l t to very coarse sand, but they most commonly occur as fine to medium grained sand.  Roundness shows wide variation,-  ranging from very angular to rounded, with the majority of the grains being subangular to subrounded.  This v a r i -  ation i n roundness i s believed by the author to be largel y due to the replacement of the grains by the c a l c i t e cement and by the matrix (figs. S3 and S 4 ) . B. Feldspar: Several varieties of feldspars are present. In the twelve thin sections that have been stained with sodium c o b a l t i n i t r i t e , potash feldspars (orthoclase and fewmicrocline) show an average of 6 . 8 percent of the entire assemblages, with a range from 3-3 to 9.3 percent. Plagioclase feldspars have an average of 12.4 percent and range from 4 . 0 to 20.5 percent.  In a l l twenty s i x thin  sections, feldspars .(both potash and plagioclase) show an average of 13.6 percent, with a range of 4 . 7 to  27.5%.  99  The plagioclase feldspars, based on t h e i r optical propert i c s , are mainly oligoclase and andesine; a l b i t e and labradorite are very rare* The majority of these feldspars are fresh and easil y i d e n t i f i e d , but some show considerable a l t e r a t i o n and can be recognized only by twinning.  As i s the case with  the quartz, the feldspars show wide variation i n size and roundness, and also show replacement by the c a l c i t e cement and the clay matrix (figs. $4 and 85). C. Rock Fragments Rock fragments include, volcanic, sedimentary, and metamorphic rock fragments'in that order of abundance.. . They have an average abundance of 4.1 percent, and range from zero to 26.1 percent.  They are most abundant i n  the coarser fractions of the .sandstones, and when the coarsest fractions are finer than medium-grained sand, rock fragments become very rare or absent. Volcanic rock fragments compose an average of 1.9 percent, ranging rorn zero (nine thin sections) to 11.1 percent.  The majority of the volcanic rock fragments are  porphyritic, with a fine grained matrix of plagioclase laths and phenocrysts of plagioclase and/or quartz ( f i g . $6).  Under plane polarized l i g h t , these fragments are  greyish i n appearance due to the scattered iron oxides  100  as i n c l u s i o n s J"  dust, present are almost  entirely  composed o f s h a l e  is occasionally silty; from zero  Sedimentary rock  they a v e r a g e 1.8  ( f i g , S7),  percent.  te,  p e r c e n t , and percent.  They h a v e (14  range from zero  an  thin  They c o n s i s t o f s l a t e ,  phylli-  s c h i s t , arid some u n i d e n t i f i e d , C h l o r i t e - ' r i e h meta-r  morphic rock P.  fragments.  M-ica Micas are ubiquitous.  p e r c e n t , - and percent  r a n g e f r o m 1.4  sandstones  t o 12 <4  percent.  About  the remainder  t o be more a b u n d a n t i n t h e  (plane-parallel,  c o n v o l u t e , and  and  55).  mean g r a i n s i z e  M o s t commonly t h e s e  90.  1  muscovite.  laminated  ripple  t i o n ) where t h e y c o n s t i t u t e t h e d a r k e r laminae 54,  5.3  T h e y h a v e an a v e r a g e o f  of the micas are b i o t i t e ,  They a r e o b s e r v e d  51,  Meta-  quartz) constitute a  minor f r a c t i o n of the rocks Composition*  s e c t i o n s ) t o 3.3  range  ( e x c l u d i n g m e t a q u a r t z i t e itfhich i s  i n c l u d e d w i t h the p o l y C r y s t a l l i n e  a v e r a g e o f 0.4  which  p e r c e n t , and  ( s e v e n t h i n s e c t i o n s ) t o 21.6  morphic rock fragments  fragments  sandstones  lamina50,  (figs. have a  ranging from very f i n e to f i n e - g r a i n e d  sand. E.  Chlorite C h l o r i t e o c c u r s i n o n l y m i n o r amounts i n t h e s e  sand-  101  stones.  I t has  from zero this  an a v e r a g e o f 0.7  percent  ( s i x t h i n s e c t i o n s ) t o 4.4  chlorite  seems t o be  e i t h e r from b i o t i t e  percent.  i n the process  or to b i o t i t e ;  and  of  Most o f  alteration  i t i s usually  g r a d i n g i n t o the a d j a c e n t b i o t i t e w i t h o u t ned  ranges  found  a well  defi-  boundary. F.  Polycrystalline  Quartz:  A l l the p o l y c r y s t a l l i n e quartz of d i f f e r e n t have been c l a s s i f i e d under t h i s c a t e g o r y . sedimentary  q u a r t z i t e , m e t a q u a r t z i t e , and  plutonic polycrystalline quartz* occurrence  o f 1.0  s e c t i o n s ) t o 7.7 G.  p e r c e n t , and  p o s s i b l y some  from zero  d a n c e i s 1.7  percent.  as c h e r t  ( f i g . 94).  p e r c e n t , and  rage  chalcedonic  quartz  T h e i r a v e r a g e abun-  f r o m z e r o t o 4.4  percent.  Other M i n e r a l s : T h e s e a r e t h e a c c e s s o r y m i n e r a l s and  the  c e o u s m a t t e r , w i t h an a v e r a g e a b u n d a n c e o f 2.3 and  (ten t h i n  Chert:  classified  H.  They i n c l u d e  T h e y h a v e an a v e r a g e  rage  A l l t h e m i c r o c r y s t a l l i n e and is  origins  r a n g e f r o m 0.3  t o 6.0  percent.  The  carbonapercent,  accessory  mine-  r a l s a r e as f o l l o w s i n d e c r e a s i n g o r d e r o f abundance  as  102  Fig.  86:  Photomicrograph of arkosic wacke showing a volcanic rock fragment (V), Crossed n i c o l s , Vesuvius B ay, Salt Spring Island. (V34-). c  Fig.  87:  Fig.  8$:  Photomicrograph of l i t h i c wacke showing shale rock fragments (S). Crossed n i c o l s . Vesuvius Bay, Salt Spring Island, (VSA3). Photomicrograph of feldspathic arenite showing siliceous cement (S). Crossed n i c o l s . Bedwell Harbour, North Pender Island (PB13).  1C3  i d e n t i f i e d with the petrographic microscope: Pyrite, epidote, apatite- hematite, garnet, and zircon.  The  carbonaceous matter i s as abundant as the pyrite, and i s present i n almost a l l the t h i n sections that have been examined. I. Unknown Minerals: These are the minerals that are unidentifyable due to t h e i r high degree of a l t e r a t i o n .  They range from zero  to 3 . 6 percent) and have an average of 1.8 percent. J. Cementt Cement i s an important constituent i n most of the thin sections studiedj ranging from zero to 42.1 percent and averaging 17.4 percent; of the l a t t e r c a l c i t e cement makes up 17.0 percent and siliceous cement 0.4 percent. Calcite cement occurs as micrite and sparite> and i t i s commonly found to replace the surrounding grains (figs. 83 and 8 5 ) , changing their size and shape. found to replace the matrix minerals.  I t i s also  The siliceous  cement, when present, has the texture of chert, but i t could be differentiated from chert by i t s form.  Chert  occurr always as grains with definite boundaries, while the siliceous cement occurs as f i l l i n g of pore spaces (fig.  88).  /  104 K.  Matrix: The m a t r i x r a n g e s f r o m 1.8  ages 1 2 . 1 p e r c e n t . all is  grains  less  consistent  minerals,  mica, feldspar,  surrounding  finely  grains  sandstone of the  on t h e  Rahmani, 196$). observed, t o  the m a t r i x  rals  "It  are,  quartz. of the  in his  clay  commonly r e p l a c e size  matrix i s of diagenetic  in  the  sand-.size  grains,  thus  PettiJohn  (1957,  (R.  indeed,  authigenic  that a l l the  and a r e  study of the  the  are  producing volume o f p.305)  o r i g i n o f m a t r i x o f greywacke  seems most p r o b a b l e  the  that  origin  in a  sandstones,  matrix mine-  result  of  Cummins (1962)  reorga-  sugges-  greywacke problem t h a t m a t r i x o f  of a primary o r i g i n ,  by comparative  substantiating  size analysis of ancient  w a c k e s and o f R e c e n t and e x p e r i m e n t a l t u r b i d i t e s . t h a t Recent  the  and-shape*  matrix-grain relationships  ( f i g s . 8 4 and 9 5 ) .  greywacke i s not suggestion  (e.g.  changing t h e i r  n i z a t i o n o f an i n t e r s t i t i a l mud." ted  matrix  m a t e r i a l and c o n t r i b u t i n g t o t h e  d i s c u s s i o n o f the stated:  clay  F i n e l y d i v i d e d m i c a and c l a y m i n e r a l s  replace  fine-grained  are  composition  Cedar D i s t r i c t F o r m a t i o n , i n d i c a t e  part of the  aver-  c l a s s i f i e d as m a t r i x  d i v i d e d mica)  ( f i g . 84)  and  consisting mainly of  and  constituents  Observations  least  56.0 percent,  t h a n 30 m i c r o n s i n s i z e . M a t r i x  m i n e r a l s and t h e  at  Constituents  i n a l l samples,  The f i n e s t  to  and e x p e r i m e n t a l  turbidites  have  his  g r e y - ... He showed  negligible  /  -105a-  (STABLE  GRAINS)  Quartz , Chert, Quartzite  Fig.89:  C l a s s i f i c a t i o n of pure sandstones, o r a r e n i t e s . A f t e r G i l b e r t (195^). 10"/ Small numbers r e f e r to specimens l i s t e d i n T a b l e 2 i &  25  AEIDSPATHIC  \10  18  \  / 50.  / A  75,  /  /  /  ( K/O  /  \ \ \  /  S I C  \ A  A t E N I T E  I I T H I C  Id spars  .50 \  A R E N I T E  Unstable (UNSTABLE  GRAINS)  Rock  Fi ne — Grair.e  Fragments  -105b-  (STABLE Fig.90:  F  e  l  d  s  P  a  r  GRAINS)  Quartz Chert, y  Quartzite  Unstable  s  (UNSTABLE  GRAINS)  Rock  Fine_Graine  Fragments  106 amounts of matrix, w h i l e  a n c i e n t e q u i v a l e n t s (the grey-  wackes) have a h i g h matrix content. For d i s c u s s i o n o f t h i s problem,the reader should r e f e r t o D o t t , J r . (I964K L. Sandstone  Classification:  For the purpose of c l a s s i f i c a t i o n , G i l b e r t ' s scheme was  adopted.  B r i e f l y , t h i s scheme f i r s t  sandstones  i n t o two major groups accourding to the  tage of m a t r i x present i n the r o c k s .  (1954)  classifies  Rocks w i t h  percen-  less  than 10 percent m a t r i x are c a l l e d a r e n i t e s , those  con-  t a i n i n g 10 to 50 percent m a t r i x are c a l l e d wackes (when m a t r i x exceeds 50 percent, the rock i s then c a l l e d a mudstone). ted  F u r t h e r s u b d i v i s i o n s are based  e s s e n t i a l components.  These components form  corners of the c l a s s i f i c a t i o n t r i a n g l e s Quartz,  on some s e l e c -  ( f i g s . 89 and  chert, and p o l y c r y s t a l l i n e quartz ;  g r a i n s " ) are grouped i n one  the  (the " s t a b l e  corner, f e l d s p a r s and  un-  s t a b l e f i n e - g r a i n e d rock fragments i n the other two ners  (the "unstable g r a i n s " ) .  tial  components were r e c a l c u l a t e d to 100 percent f o r  each sample. seventeen  T h e r e f o r e , these  According to G i l b e r t ' s  cor-  essen-  classification,  samples are a r e n i t e s and nine are wackes. Out  the seventeen  of  a r e n i t e samples, nine samples are f e l d s p a t h i c  a r e n i t e , f i v e are arkose, two are quartz a r e n i t e , and is lithic  90).  a r e n i t e ( f i g s . 91,  92,  and 93).  Out  wacke samples, f o u r samples are arkose, two  one  of the nine  are f e l d s p a t h i c  107  F i g , 91:  Photomicrograph o f q u a r t z a r e n i t e . Crossed n i c o l s . V e s u v i u s Bay, S a l t S p r i n g I s l a n d , (V26).  F i g . 92: ' Photomicrograph of f e l d s p a t h i c a r e n i t e . Crossed n i c o l s . V e s u v i u s Bay, S a l t S p r i n g I s l a n d ,  (5a).  F i g . 93:  Photomicrograph o f a r k o s i c a r e n i t e . K i s s t a i n e d p o t a s h f e l d s p a r . Crossed n i c o l s . Mayne I s l a n d . (M4-).  108  wacke, one i s a r k o s i c wacke, one i s l i t h i c wacke, and i s q u a r t z wacke ( f i g s . 86,  87,  one  and 9 4 ) .  There was no s i g n i f i c a n t v a r i a t i o n i n c o m p o s i t i o n of the sandstones w i t h s t r a t i g r a p h i c p o s i t i o n i n the formation.  A l s o such v a r i a t i o n has not been observed  lateral-  l y throughout the s t u d y a r e a .  $. GRAIN SIZE DISTRIBUTION Grain s i z e d i s t r i b u t i o n of f i f t e e n sandstone  samples  were determined i n t h i n s e c t i o n w i t h the p e t r o g r a p h i c microscope.  The l o n g dimensions o f 100 g r a i n s were mea-  sured i n each o f the 1$ t h i n s e c t i o n s .  E x c l u d e d from  these measurements are t h e g r a i n s f i n e r t h a n 0.03  mm  ( i . e . t h e m a t r i x ) * F i g u r e 96 shows h i s t o g r a m s o f t h e g r a i n s i z e d i s t r i b u t i o n of these samples.  No  attempt  was made t o c o n v e r t the t h i n - s e c t i o n s i z e  distribution  (number) i n t o the s i e v e - s i z e d i s t r i b u t i o n  (weight) as  done by Friedman  was  (1958 and 1 9 6 2 ) , s i n c e he d e a l t w i t h  w e l l sorted,, q u a r t z - r i c h  sandstones.  Most o f the samples have f a i r s o r t i n g , and t h e major i t y have the f i n e admixture d o m i n a t i n g .  Mean g r a i n s i z e  of samples t a k e n from A - d i v i s i o n are i n t h e medium-grained sand range,'those from B - d . i v i s i o n samples i n the f i n e g r a i n e d sand range, and those from C - d i v i s i o n samples i n the v e r y f i n e - g r a i n e d sand range, ( f i g . 9 6 ) .  109 a  F i g . 94:  Fig.  95:  F i g . 97:  Photomicrograph of a r k o s i c wacke showing chert rock fragment ( C ) . Crossed n i c o l s . Vesuvius Bay, S a l t S p r i n g I s l a n d . Photomicrograph showing the replacement of g r a i n s by the surrounding c l a y - s i z e m a t r i x . Crossed n i c o l s . Vesuvius Bay, Salt Spring Island. (5c). T i l t compensator used f o r measurements paleocurrent d i r e c t i o n s . The s c a l e i s inches.  of in  Grain Count Per Cent o  tt). 5'  o  1  o  F  o I  o I  o I  o  5  S  e  I  I  !  I  o  g  o  o  'I  I  I  I  I  I  i  i i i i  i  T  i  i  i ir  i  I I  i  i O vO  cr i  3*  i r  3  i  i i i i  IT F i g . 9 6 : Histograms o f the t h i n - s e c t i o n frequency d i s t r i b u t i o n o f sandstone framework g r a i n s c a l c u l a t e d from g r a i n KHMHS s i z e counts i n t h i n s e c t i o n . Numerals r e f e r t o specimen numbers.  i  i  i  i i  110  9.  DIRECTIONAL  A.  orientations  sedimentary order  to  determine the  measured  regional are  f i e l d  97)  used  i n  that the  reading  of  the  sedimentary  composed  two  2/3  arm. has  hinged  The the  (sole  the  l e l  using  other  Next, to  the  the the  arm  The  spirit i s  The  s t r i k e of the  spirit  comes  other  arm  t i l t  (1962,  kept  i s  a  against  arm  with  the  bed.  the the  contact  with  i s  aligned  to  indicator  of  each  with  spirit  as  the a  the  i s  arm  to the  are  one arm  bedding l e v e l  that plane  now  compensator  hinge  line  bedding  coincide (e.g.  the  non-magnetic  lower  Then  l e v e l arm  of  mounted  horizontal  reorien-  compensator  dimensions l e v e l  done com-  instant  used  i n  paleocurrent  A  of the  was  Pouma  This  (Bouma  dip  obtain  This  by  for  structures. arms  A  study  for  o r i g i n a l orientation  l e v e l held  bed).  developed  end.  inch.  s p i r i t  indicates  the  one  compensator  of  rotated  at  1/3  X  wooden  to  i n  pattern.  correction  measurement.  present  directional  metal)  was  f i e l d  paleocurrent  t i l t e d ,  during  d i r e c t i o n a l  the  direction.  the  of  i n  o r i g i n a l current  ( f i g .  and  measured  neccessary  pensator  tation  the  available  was  i n  was  v/ere  beds  directly  X  PALEOCURRENTS  a l l the  orientations  pre-tectonic  p.25)  of  structures  Because  6  AND  Methods The  the  STRUCTURES  with  groove  i s  u n t i l  plane. or  paral-  casts,  Ill  f l u t e c a s t , ... e t c . ) .  Then the compensator i s swung  back to the h o r i z o n t a l p o s i t i o n u s i n g the s p i r i t arm as a hinge l i n e .  The  o t h e r arm now  o r i e n t a t i o n of the c u r r e n t i n d i c a t o r  level  i n d i c a t e s the  before t i l t .  Then,  u s i n g a B r u n t o n compass, t h i s d i r e c t i o n i s measured. The  s t r u c t u r e most commonly measured was  the f o r e -  s e t l a m i n a t i o n a s s o c i a t e d w i t h the current r i p p l e , l a m i n a t i o n of the C - d i v i s i o n .  I n o t h e r p l a c e s , where d i r e c t i -  o n a l s o l e marks were a v a i l a b l e (e.g. f l u t e casts,- groove c a s t s , and bounce c a s t s ) , the- c u r r e n t d i r e c t i o n , was corded from them and  compared w i t h t h a t r e c o r d e d  f o r e s e t l a m i n a t i o n w i t h i n t h e bed. per bed was  U s u a l l y one  re-  from the reading  recorded by t a k i n g the average d i r e c t i o n of  the c u r r e n t i n d i c a t o r s i f t h e r e i s any v a r i a t i o n . e v e r , I f the v a r i a t i o n exceeds 2 0 ° , taken per bed.  Due  How-  two r e a d i n g s were  t o the s c a r c i t y of w e l l exposed  lower  bedding s u r f a c e s , few measurements of s o l e markings area v a i l a b l e from the study  area.  B. P r e s e n t a t i o n and I n t e r p r e t a t i o n of Data Rose diagrams of the c u r r e n t d i r e c t i o n s were made f o r the V e s u v i u s Bay area on S a l t S p r i n g I s l a n d , and the B e d w e l l Harbour area on North Pender I s l a n d The  in  (fig.cS).  numbers w i t h i n the c i r c l e s of the rose diagrams i n d i -  cate the number of r e a d i n g s t a k e n i n t h a t p a r t i c u l a r  area.  P i g . 98  113  In  the other  rose was  diagrams available Figure  the  localities were  i n each  98  shows  northwest,  incidence  not  shown  of these that  structures  (soft-sediment  presumably  moved  i s the  lamination tation tion  of  gravity  tion  the minor by  part  turbidite  folds  t h e -drag  of  foreset  probably  down  that  example  Island,  controlled which  the t u r b i d i t y  of  and  carpet  An  the  sediment  foreset  the  orien-  deforma-  which  i s  i s f o u n d , .on t h e  where  the orientation, of  coincides  of the pebbly  co-  directional  the paleoslope.  traction  from  The  structures)  of the soft  from  reading  flowing  southeast.  the t u r b i d i t e s ,  lamination  resulting  were  i n orientation  ..Another  one  of the gravity  suggests  of a  Saturna  of the thinning  latter  with  controlled,-  southern the  coincidence  associated  caused  currents  deformation  flowing  only  the turbidite's  downslope,  98,  of figure  l o c a l i t i e s .  the orientation  also  since  stsa±±feh, a n d of  and  example  the  northeast,  structures  were  t h e map  constructed  i n orientation  currents  on  with  mudstone  downslope  the  direc-  sequence,  slumping.  the  114  10,.  A.  down  Basin  George t r y ;  Since  the turbidity  the slope  section, basin at  right  Pender  were  angles  currents  islands, trending line  boundary  607).  shape I l l i t e with  therefore  area,  were  directions  were  and'normals  might  slope  to the  projected  t h e shape  northeast, on t h e  southeast,  respectively.  w i l l  Nnrth  I f the  eastward a  slope  result. of the  contour  ( f i g . 19),  from  the  and i t s trend  of the formation^  contour  This eastern  limits,  ( i . e . 1957,  coincides approximately  obtained  trend  i n  Kaolinite/  also  coincides  of the outcrops  The n o r t h e r n  lines  to the  of the shore-line, PettiJohn,  the southeast-northwest  structures  and  The  southeastern  but not the eastern  the contours  ratios,  and  d r a w n -to t h e m ,  indicate  the trend  Saturna  dipping  and northwest  direction.  the paleoslopes  eastern,  previous  approximately  the northwest,  southeast-northwest  This  with  Spring,  flowing  within the  lines  current  from  i n the  somewhere  contour  on S a l t  of the basin  indicates p.  west,  the current  contour  with  northeastern,  o f the study  outer  that  flowing  apparently  as concluded  t o the measured  I s l a n d s were  southwest,  line  slopes  and southeast,  parts  of  inferred  as measured  northwestern,  c u r r e n t s were  of the basin,  i tcan be  there  east,  PALEQGEOGRAPHY  and  and  southern  115 parts of the basin may be delineated by the termination of the outcrops just south of Nanaimo City to the northwest, and on Sucia and the Orcas Islands to the south and southeast.  The Late Cretaceous age of the lower part of  the non-marine Chuckanut Formation, (W.S. Hopkins, Jr.., 1966), which was possibly a continental equivalent to the marine Cedar D i s t r i c t Formation,, suggests that the shore line of the southeastern part of the basin was somewhere between the mainland of northwestern Washington State and Sucia Island. Paleontological evidence • (J.E. Muller and J.-A. Jeletzky, 1967, and J.E. Muller 1968, personal communications) suggests that the basin was opened on i t s western boundaries to the P a c i f i c Ocean. Absence of currents flowing from the west and the south might be due to one or both of the following reasons;  (1) there were  no t u r b i d i t y currents flowing from these directions, (2) the regional dip of the basin was to the west,, southwest, and south, therefore t u r b i d i t y currents.could not flow up the regional dip. From the above, some tentative conclusions may be made regarding the shape and. dimensions of the Cedar Dist r i c t basin of deposition.  But i t must be emphasized that  the available evidence i s sparse and scattered, thus these conclusions' are open to further discussion and  116  modification.  The  b a s i n had  an e l o n g a t e shape w i t h i t s  longest axis trending southeast-northwest. and  northwestern boundaries  may  have been l o c a t e d j u s t  s o u t h o f t h e c i t y o f Nanaimo and t h e s o u t h e r n and  Gabriola Island, while  southeastern boundaries  somewhere on t h e San  I t s northern  were  probably  Juan I s l a n d s between Washington  State northwestern  c o a s t , and  To t h e w e s t i t was  open t o t h e P a c i f i c Ocean t h r o u g h  paleo-Yancouver  Island(s).  S u c i a and  The  the Gulf I s l a n d s .  l o c a t i o n of the  b o u n d a r y o f t h e b a s i n i s n o t known, b u t  eastern  indications* of  t h e Nanaimo G r o u p h a v e b e e n t r a c e d on c o n t i n u o u s p r o f i l e s t o about the m i d d l e (D.L. T i f f i n ,  of the S t r a i t of  p e r s o n a l communication);  Upper C r e t a c e o u s  also,  r o c k s were encountered  b e n e a t h t h e F r a s e r D e l t a , (W.S,  the  Hopkins,  seismic  Georgia, non-marine  i n two  deep w e l l s  J r . , 1966).  T h e r e f o r e the e a s t e r n boundary of the Cedar D i s t r i c t  ba-  s i n c o u l d be somewhere b e t w e e n t h e B r i t i s h C o l u m b i a m a i n l a n d and  Saturna-Mayne-Galiono  p r e s e n t day W.H.  S t r a i t of  Mathews (1958) h a s  reported at l e a s t  r o c k s i n t h e Mount  area of B r i t i s h Columbia,  oldest formation  I s l a n d s i n the  Georgia.  f e e t of marine sedimentary map  Valdes  He  Garibaldi  has d a t e d t h e . l o w e s t  ( t h e Cheakamus F o r m a t i o n )  quence as "mid-Upper C r e t a c e o u s " .  20,000  of t h i s  Therefore, at  se-  least  and  117 parts of the Mount Garibaldi sequence may be correlative with the Cedar D i s t r i c t Formation.  I t i s not known  whether these were deposited i n a separate basin or i n a possible northeastward extension of the Nanaimo Basin. B. Dispersal The following facts suggest that the major source area f o r the sandstone and the coarser elastics was situated to the east and southeast of the study area: (1)  Paleocurrent measurements indicate t u r b i d i t y  currents were flowing mainly from the eastern and southeastern parts of the study area ( f i g . 98). (2)  The high percentage of sandstone i n the central,  southern, and . southeastern parts of the area relative to i t s very low percentage i n the northern part of the study area. (3)  Restriction of the North Pender Island breccia  (figs. 30 and 31) and the Saturna Island pebbly mudstone ( f i g s . S and 28) to the south and southeast, and the wedging .out. of the pebbly mudstone toward the northwest, suggest a source from the east, and southeast. The distance to the source area i s d i f f i c u l t to determine, but the occurence of breccia on North Pender Islamd, and the  very poorly  sorted  pebbly mudstone on  Saturna Island might Indicate the closeness of the source  -118*  50  C  Fig.99:  A  Each group o f t u r b i d i t e s i s p l o t t e d on the d i a g r a m a c c o r d i n g t o the p e r c e n t a g e of beds i n the group begining with A - d i v i s i o n , B - d i v l s i o n , & C-division. F i e l d 1 corresponds r o u g h l y w i t h the l o w e r f l o w regime o f Simons & o t h e r s (1965), and f i e l d s 2 & 3 c o r r e s p o n d w i t h the upper f l o w r e g i m e , 3 r e p r e s e n t i n g a h i g h e r regime t h a n 2.  119  area  to  these  parts  In  parts  of  detail,  and  different that at  77%  bidites been et  turbidite the  base  Adopting  the  (1965),  considers were  deposited  area  for  current however, i f  the  area  within  the  C.  to  E  (1967,  p.  24,  i n f i g . formed  areas  relative  from  the  source.  flow  regime,  even  4),  the  regime  tur-  lower to  have  of  Simons  (1967)  Walker,  flow  the  regime  source  the  reduction  The  author  currents  d e p o s i t i o n from  units).  apparently  interpretation  most ..turbidity  then  lower  i n the  found  C-division  f i g .  flow  99.  the  i t was  turbidite  c u r r e n t s , clue t o  alternative of  with  Formation lower  i n  i s  feels,  possible;  i n a  them would  i n  given be  i n proximal  largely  areas,.  Provenance The  varied  composition  rock  feldspar cline), tonic  an  velocity low,  away  recorded,  C  turbidites  measured  occurrence*of  are  i n the  i n d i s t a l  of  start  District  turbidity  that  v/ere  scheme  was  were  units  indicated  velocity  area.  frequency  divisions  largely  that  the  the  Cedar  as  study  sections which  turbidite  Walker's of  the  ( i . e . these  deposited  a l  the  i n which  of  their  of  types  i n the  (andesine, and  biotite  and/or"low  of  to  the  sandstone  source  oligoclase, indicate medium  area.  Abundance  o r t h o c l a s e , and  acidic  grade  framev/ork  to  indicates of  quartz,  micro-  intermediate"plu-  metamorphic  rocks  as  120  major  source  ments,  especially  fragments, canic line the  rocks.  sedimentary  indicates  rocks  source  I t was area  Looking  Washington,  196l),  area  rocks  ( t h ea r e a  around  source  Jurassic  low grade  Cascade  could  some  gneisses, Cedar  D i s t r i c t The  centage stone) of  large  post  rocks  Cretaceous,  areai  which  However, t h e  east,  where p r e -  a r e exposed  and dated  of Washington,  of quartz  i n the  i n t h e San Juan  a r e exposed  some  of the  diorites sediments  as  196l); and t othe  sandstones. thickness of-the  area,  formation,  ( i . e . l a r g e volumes  i n the central,  that  with  further  possibly yielded  o f sandstone  the study  suggest  mainly  ( G e o l o g i c Map o f  to the east  source  rocks  crystal-  section that  of Bellingham)  ( G e o l o g i c - Map  composed  quite  map  To t h e s o u t h e a s t ,  crystalline  pre-Carboniferous rocks,  be s t i l l  metamorphic  Mountains.  Islands,  these  the c i t y  a possible crystalline  ultimate  land  covered  vol-  was t o t h e e a s t a n d  at the geologic  i s now l a r g e l y  rock  and  mentioned  i n the previous  the nearest  frag-  and v o l c a n i c  t h e above  suggested  of rock  o f sedimentary  f o rt h e s a n d s t o n e s  southeast.  study  (shale)  the presence  associated with  rocks.  obscure  T h e common o c c u r r e n c e  southern,  area  of the  and southeastern  and the angularity  the source  the high  per-  sandparts  of the grains a l l  was an area  of high  relief  121  that of  had undergone  the feldspars  area., w h e r e in  rapid  further  mechanical  breakdown  of the source  where  tion,  i twas  was  l o w r o l l i n g muddy  large  shale  rivers  suggests  composes  assumed  that  parts  of the study  a  deeper  fauna  part  of the basin,  to the east  o f t h e Cedar  D i s t r i c t  a l i t t o r a l  deposition,  Breitsprecher  of  the study  of the foraminifera  in  Sucia  deposited to  Jeletzky  The  water  Formation Almost  area  distant  t o upper  and c a l l e d  D i s t r i c t n e r i t i c  near-shore  the l i t t o r a l  c o u l d be v a l i d  f o r i t s on t h e b a s i s  and the megafossil  temperature".  them  indicates  a l l previous  environment  Formation depth  was  and J.A.  shallow depths parts  fauna  i n tropical  J.E. Muller  f o rthe shaley, fossiliferous  above  coarse  more  (1962),•concluded,  t h e Cedar  (1967) s u g g e s t e d  deposition mation,  that  i n " l i t t o r a l  subtropical  no  and southeast.  environment.  suggested  Island,  t h e r e were  of Deposition  i n a marine  have  these  sec-  t o the north  t o supply  Environment  workers  area  areas  the shorelines  deposition  o f the exposed  the source  factor  and n o r t h -  or elevated source  been  The  the important  To t h e n o r t h 95%  source  where  might  Di  about  of the  plain  alternatively,  from  rocks.  Freshness  coastal  materials; have  a r i d i t y  w e a t h e r i n g was  west,  a  u p l i f t and erosion*  of  of the for-  facies.  f o rthe fossiliferous  shaley  122  parts  of the formation,  where  turbidites  a r e abundant,  deposition  place  at greater  than  depths,  below  wave  where, l a m i n a t i o n  sandstone The ern  could  tions  since  depths  i n the bottom  parts  of the basin of f o s s i l s  abundance  shales,  stagnation  ments  were  the  periodic  basin  water  that  was  District 1952;  basin  prevented  apparently  and t h e open 196?;  at  lamina-  environ-  by  northern  the almost  of the basin, matter  of euxenic  may The  connection ocean Muller  and  by  i n the Com-  environOne  the central part  which  complete  concretions.  by two f a c t o r s .  area. a  north-  o r i n deeper  and reducing  and carbonaceous  this  1967)  and J e l e t z k y ,  and t h e c a l c a r e o u s  into  of the  rocks.  and the development  Breitsprecher,  convolution  deposited.either  parts  currents  taken  depths  h o r i z o n t a l and cross  introduction into  oxygenated  have  o f the c e n t r a l and  i n these  of turbidity  there  was  are suggested  probably  must  o f the c e n t r a l and  conditions  of pyrite  plete  and  of the section  i . e . at  as t h e t u r b i d i t e s ,  waters  sandstones,  parts  (Muller  i n these  stagnant  ments  absence  area  thin,-delicate,  are preserved Partial  the  preserved,  of the study  t h e same  water,  be  l i t t o r a l  u n f o s s i l i f e r o u s shale  parts  about  base,  but i n other  was  of the  have  transported  second  factor i s  between  to the west and J e l e t z k y ,  the  Cedar  (Usher, 1967,  123  and  Muller,  have the  served open  to  during  summary,  lower  shaley  eastern  parts  neritic  depths,  to  animal  shaley basin  resulting reducing dites and  of  life..  from  waters  and  the  suggest  water  scarcity  the  central  partial  upper  part  parts  to  the  of and  stagnation  of  storms.  of  fossils,  and  and  occurence the  suggests  to  the of  i n df  formation abundant  deepening  the the  conditions  formation, i n the a  upper  favourable  parts  l i v i n g  i n  south-  fossils  northern  from  and  l i t t o r a l  these  might  basin  southern  unfavorable  The  the  c o n d i t i o n s were  The  due  which  abundance  of  basin  to  fluctuations  nature  environments'.  i n the  new  intervals  probably  southeastern  basin.  the  communication)  t i d a l  where  facies-of was  personal  introduce  ocean  In the  1968^  of  of turbi-  central the  124  1 1 . SUMMARY AND CONCLUSIONS 1.  Shale composes about 73% by t h i c k n e s s o f the  Cedar D i s t r i c t F o r m a t i o n . the n o n - s h a l e p a r t .  Sandstone makes the b u l k of  Calcareous c o n c r e t i o n s . a r e  s c a t t e r e d i n the s h a l e s and the 2.  sandstones.  Two types o f s h a l e o c c u r r e n c e s are a.  present  present:  Continuous sequences of more t h a n 100 f e e t i n t h i c k n e s s , w h i c h may o r may not be fossiliferous.  b,  T h i n beds i n t e r b e d d e d w i t h sandstone ( i . e . flysch-type  3.  Among s h a l e s o f t y p e  beds  shale). (a) above,  fossiliferous  s h a l e s are r e s t r i c t e d t o the s o u t h e a s t e r n p a r t of t h e study a r e a ( S u c i a and S a t u r n a I s l a n d s ) , where v e r t i c a l l y a s s o c i a t e d w i t h t u r b i d i t e sequences. fossiliferous  they.are The u n -  s h a l e s o c c u r toward the west and northwest  (North P e n d e r , S a l t S p r i n g , Mayne, and Vancouver I s l a n d s ) and a r e l i k e w i s e v e r t i c a l l y a s s o c i a t e d w i t h t u r b i d i t e sequences,  except on Vancouver I s l a n d at the n o r t h w e s t e r n  end o f t h e s t u d y a r e a , where no t u r b i d i t e s are 4'.  I n t h e f l y s c h - l i k e sequences,  present.  the r h y t h m i c  i n t e r b e d d i n g of sandstone and s h a l e b e d s , and the t y p i c a l t u r b i d i t e s t r u c t u r e s e x h i b i t e d by the sandstones of the Cedar D i s t r i c t F o r m a t i o n , a l l i n d i c a t e t h a t d e p o s i t i o n of  125 the rhythmic (flysch-like) sequences took place by turb i d i t y currents* 5.  Dominance of the C-E turbidite units, indicates  that the deposition of these turbidites took place largel y within the lower flow regime, 6.  Calcareous concretions, most abundant i n the  shalesj have features suggesting they were formed i n the early stages of diagenesis, probably shortly after burial. 7.  Paleocurrents, and l i t h o l o g i c l a t e r a l variation  indicate that the major source area for the coarse e l a s t i c s i n the Cedar D i s t r i c t Formation was situated to the, east and southeast of the study area, 8.  Mineral assemblages of the sandstones suggest  that the major source rocks were acidic to intermediate plutonic and/or low to medium grade metamorphic rocks. 9.  Pre-Jurassic low grade metamorphic rocks of  the Cascade Mountains to the east, and the pre-Carboniferous c r y s t a l l i n e rocks of the San Juan Islands to the southeast served as possible source areas f o r the coarse e l a s t i c s . 10.  Composition of the sandstones suggests the  major source areas were possibly regions of high r e l i e f that had undergone rapid u p l i f t and erosion.  126  11.  Rocks i n the  perienced  mainly  12. of the depths. sited  a r e a a p p e a r t o have  of the  shaley, f o s s i l i f e r o u s  took place  in littoral  to upper  study  a r e a was  d e p t h s as t h e  turbidites,  d e l i c a t e , h o r i z o n t a l and i n these  c e n t r a l and  deposited  The  northern  unparts  e i t h e r at about the  cross l a m i n a t i o n s are  of  same  or i n deeper water, s i n c e  Paleontologic evidence suggests that  took place  i n a somewhat r e s t r i c t e d  connection  w i t h the  14.  thin,  preserved  open o c e a n t o t h e  P a l e o n t o l o g i c and  deposition  basin having  a narrow  west.  mineralogic  gests t h a t the bottom c o n d i t i o n s of the  and  neritic  rocks*  13*  northern  parts  f o r m a t i o n were depo-  i n d e e p e r w a t e r , b e l o w t h e wave b a s e ; shale of the  ex-  weathering.  T u r b i d i t e sequences of the  fossiliferous the  mechanical  Deposition  formation  source  evidences central  p a r t s o f the b a s i n o f d e p o s i t i o n were  sugand  stagnant  reducing, 15*  Facies relationships  s i t i o n had eastern,  s u g g e s t the b a s i n o f depo-  i t s l o n g e s t d i m e n s i o n t r e n d i n g SE-NW.  southeastern,  and  southern  b o u n d a r i e s were  s i t u a t e d between the mainland of B r i t i s h t o n and  the Gulf-San  northwestern  Juan I s l a n d s .  Its  Columbia-Washing-  I t s northern  and  b o u n d a r i e s were p o s s i b l y near the c i t y  of  127  Nanaimo and G a b r i o l a I s l a n d ,  To. t h e w e s t  t e d a t l e a s t p a r t i a l l y t o t h e open 16.  i t was  connec-  ocean.  In the southeastern part of the study area,  a l t e r n a t i o n o f t h i c k , f o s s i l i f e m u s s h a l e s e a u e n e e s , and sequences which a r e p r e d o m i n a n t l y t u r b i d i t e s  suggests  f l u n c t u a t i o n s i n the depth o f the basin f l o o r , t o changes 17. marine  i n sea l e v e l o r t o t e c t o n i c  e i t h e r due  movements.  The Nanaimo Group i n c l u d e s c o a l - b e a r i n g , n o n -  r o c k s w h i c h w o u l d be c a l l e d  by many g e o l o g i s t s .  a typical  The C e d a r D i s t r i c t  ever, contains t u r b i d i t e  "molasse"  F o r m a t i o n , how-  sequences w h i c h a r e t h o u g h t by  some g e o l o g i s t s t o be t y p i c a l o f " f l y s c h " .  This juxta-  p o s i t i o n of u n l i k e f a e i e s r e s u l t s from f 1 u c t u a t i o n s i n w a t e r d e p t h d u r i n g d e p o s i t i o n o f t h e Nanaimo  Group.-  128  1 2 . 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A . , and J e l e t z k y , J.A., 1967, S t r a t i g r a p h y and b i o c h r o n o l o g y . o f the Nanaimo Group, Vancouver I s l a n d and G u l f I s l a n d s , B r i t i s h • C o l u m b i a : G e o l . Survey Canada, paper 67-1» p t . B, p. 3 9 - 4 7 . N e d e r l o f , M.H., 1959, S t r u c t u r e s and sedimentology o f the Upper C a r b o n i f e r o u s ' o f the Upper P i s v e r g a V a l l e y s , C a n t a b r i a n Mountains, S p a i n : P u b l i s h e d T h e s i s , U n i v . L e i d e n , N e t h e r l a n d s , p. 6 0 3 - 7 0 3 .  132  Newberry', J.S., 1857, R e p o r t on t h e g e o l o g y . o f t h e r o u t e of Williamson'.s .survey i n C a l i f o r n i a ' and Oregon,; U i S i Pac. R.R. E x p l . , pt,. 2, p, 5-68, Parham., W i E i ; 1966 j L a t e r a l v a r i a t i o n s o f c l a y m i n e r a l assemblages i n modern and a n c i e n t sedimentsiI n t e r n a t . C l a y Conf. P r o c , v. 1, p. 135-145. 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Survey Canada, Mesozoic F o s s i l s , v. 1, pt. 2, p. 93-190. Williams, Emyr, I960, I n t r a - s t r a t a l flow and convolute folding: Geol.' Mag. j v. 97, p. 203-21/4-. Wynne, T.E., 1959, The geology of the Gulf Islands, B r i t i s h Columbia; Unpublished B.Sc. Thesis, Univ. of B r i t i s h Columbia, 34 p.  135  13.  Use Graph chart. ted  of the Turbidite  paper  with  version  method  of  i n the f i e l d  and subcolumns  as a  were  logging  tabula-  (seethe table  The f o l l o w i n g i s a  (1962)  (Unit  o f each  was measured the units  modi-  (1967)  and Walker's  thickness) individual  and tabulated  have  SECOND  to obtain  COLUMN column  subcolumn  turbidite under  t o measure  an average  (Turbidite unit has been  recording  divided  unit i n  this  s u r p r i s i n g l y constant  no a t t e m p t w a s made  the strike  This  Chart  i n the f i e l d  appendix). T  COLUMN  laterally, along  measured  o f Bouma s  Thickness inches  used  i n columns  this  Loggin  logging.  FIRST  Since  were  A l lproperties  enclosed  each  rolls  on t h e chart  fied  APPENDIX  column. thickness  the  thickness  thickness.  divisions) into  the properties  four  subcolumns,  of a single d i -  vision. For  A-division, thickness,  presence,  andcolor  were  using  made  were  a hand  grain  recorded. lens  size,  Grain  carbonate  size  (xlO) and recorded  cS:  Coarse-grained  sandstone  mS:  Medium-grained sandstone  fS:  Fine-grained  sandstone  measurements as follows:  136  Color  cZ:  Coarse-grained  sZ:  Sandy  was  For sion was  I  by  mG:  Medium  1G:  Light  bG:  Brownish  grey  gnG:  Greenish  grey  measured.  added  using  to  y  y  /  r x A  the  same  the  the  thickness,  type  recorded; the  No  f i e l d ,  s i l t y  to  -  Oversteepened  its  symbol  was  was  c  subcolumn  exhibited  were  by  logged:  lamination  lamination  lamination division  made  color, to  a l l of  size.  recorded,  i s :  foreset  presence,  almost  f o r A - d i v i -  extra  structure  ripple  interturbidite  since  as  lamination  Current  attempt  an  categories  Foreset  sandy-clay  structure  of  following  carbonate  properties  C-division,  Convolute For  symbols:  grey  -  -"""^  following  grey  For  record  division;  the  Grey  B - d i v i s i o n , the  were  that  s i l t  recorded  G  siltstone  that  and  measure  the  Under  (DE-division), structures grain  size  were i n  i n t e r t u r b i d i t e s have  structures,  only  i s plane-parallel  one  lamination;  13 THIRD  COLUMN  Sedimentary  7  (Sedimentary structures  structures)  have  been  divided  into  two  types: 1.  Bedding They  bedding  plane  are sedimentary  plane.  secondary  structures  These  were  structures  divided  into  present  on the-  primary  and  structures: a.  Primary  structures  =^•2== Channelling O — z z -  Flute  Casts  - r ^ ^ ' Groove b.  Secondary —'  7.... B e d (A  Casts  structures  Load  d-^-*  (loaded)  Casts  Burrows  internal  structure  bed usually  includes  one  o r more  turbidite  division). These graded  bedding,  classified  and  are found  disturbed  as primary  structures); tional  structures  bedding,  structures  secondary  structures).  The  within etc.).'  the bed, (e.g. They a r e  ( i . e . depositional  structures  following  ( i . e .  symbols  post-deposi-  were  used:  138  a.  Primary.Structures Disturbed bedding (caused by high density turbidity currents) Detached As  above  clasts but bent  Combination second  of the f i r s t  Combination of the second, and t h i r d Graded b.  Secondary  and  f i r s t ,  bedding  structures  Burrows Calcareous concretions random orientation  with  Widely separated calcareous concretions elongate parallel to bedding As a b o v e b u t u s u a l l y i n s t r i n g s more t h a n one  <£z£> D i s c o n t i n u o u s  bed of joined concretions  calcareous FOURTH Under measured  COLUMN this  from  (Paleocurrent directions)  column  the direction  directional  sedimentary  o f  paleocurrents  structures was r e -  corded . FIFTH  COLUMN  Turbidite from  t h e base  (Unit  number)  u n i t s were  numbered  of the section with  i n the f i e l d , number  starting  one; t h e numbers  139  increase  upward  SIXTH  COLUMN  This specimen  any  i n  the  (Specimen  column was or  SEVENTH  COLUMN  This  to  particular EIGHTH The  nature  used  specimens  is  section. number)  to  taken  record from  (Photograph  record  the  position  each  i n  the  number  of  following  symbols  were  the  unit.  number) number  measured  (Nature  of  separate  photograph  COLUMN  of  the  bedding) used  taken  at  section. '  to  describe  the  bedding: Beds where planes are  upper and l o w e r almost straight.  Beds where the lower bedding p l a n e i s u n d u l a t i n g (due to r i p p l i n g , loading or sole marks). Beds where boundaries NINTH This mentioned  COLUMN  to  be  field  (Remarks)  column  records  above.  Such  structures,  bed  and  interpretations  observations  observations  attitude,  inadequate,  upper and lower are undulating.  the of  sketches recording the  other  include where of  measured  than  tectonic  photos  some  those  proved  preliminary  properties.  SfiHpLE  OF T O R B ) * D I T ^  SEQUENCE  LOSGJUS  CHART  tv<Uz)an<( Walker O .) • 67  TURBIDITE:  V  C c  c  -s  * c  u  V» <  ( / > c  -V  o  £.0  30-0 7-5-  '£  t>  tf c k  o  cS  X  /5-0 cS  X  —  0 0  0  26-0 cS  •—  STRUCTURES  4  1 0  a) rt c cl  C >-> <u "+J a c & -A  L  o o  &  20 m S  IG  50 roS  IX  mS  s s  c  'E  Q u  X  IG  50  u c C - 0 -Q  IS •s  L  0  L.  JAA  2-3 fS J l  X  U  u  .e oE  L.  Or/--  6-5 X  IG s o  fS  3 0fS X  L.  •tf  IG  V  -cs  •3  m& r -  X  m G 40  r-  c  L.  tf  -o <L  3 n  vo  .G  of  3 V  i •o  o  CL.  »)  *-+^,. -0'  a  55-235  1  1  —  Y1A  3  cy  0  O  \^ 1  —  —  1  1  pk.-fco A l Sfc»y*  7 1 " ht6S°W •  cm  —  4«niif Aiibn  •  •  ai  w  -V  Al  •£  %)  s  of  ol  —  1  r  70  c  7-N  .r ~g  •z  u u o  -ft  STRUCTURES  *J 10  50 r»S —  J  «->  <_  »> c __Q  v»  u  -5  |MTfcRTUR8lDlTc  DP  u  •s .o  DWIS/O//.*  6  A  £  U^IT  

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