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The mineralogy of the sands in the vicinity of Vancouver Leckie, Phyllis Gilmour 1936

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THE MINERALOGY OF THE SANDS IN THE VICINITY OF YANG OUTER hy PHYLLIS G . LECKIE A Repor t s u b m i t t e d f o r the Degree o f MASTER OF ARTS i n the Department o f Geo logy The U n i v e r s i t y o f B r i t i s h Co lumbia A p r i l , 1936 . CONTESTS Page FOREWORD . ............. 1 INTRODUCTION A summary o f t h e g e o l o g y o f t h e a r e a i n th e v i c i n i t y o f V a n c o u v e r .......... 2 C h a p t e r I LABORATORY METHODS C o l l e c t i n g o f sand samples .............. 4 M i n e r a l a n a l y s i s o f samples .............. 4 C h a p t e r I I THE MINERALOGY OF THE SANDS B o u l t b e e ' s B e a c h . C a u l f e i l d B e a c h E a s t Beach . . '10 Mouth o f C a p i l a n o R i v e r ,...............» 11 Second Beach . . . . . . . . . . . . . . . . . . . . . r . . . . . . 12 K i t s i l a n o B e a c h 13 U n i v e r s i t y Beach . . . . . . . . . . . . . . . . . . . . . . . . 14 C h a p t e r I I I CONCLUSION The d i s t r i b u t i v e p r o v i n c e s .............. 16 The p r o b a b l e s o u r c e s o f the m i n e r a l s .... 17 LIST OF ILLUSTRATIONS Pag© M i n e r a l s ( i n c o l o r ) . . . . . . . * 1 Figure 1 - Percentage of Heavy Minerals g Percen tage of M a g n e t i t e . . . . . . . . . . . Figure 2 - Percentage of carbonates . 11 Figure 3 ~ Mineral occurrencec. 16 Figure 4 - Percentage of epidote and hornblende.... 17 Map -. Vancouver and v i c i n i t y «....«.«.....* 7 PLA TS I VOL-CAN/C GLASS ZIR C OA/ -1-FOREWORD T h i s p a p e r i s a s t a t e m e n t o f t h e r e s u l t s o b t a i n e d from the a n a l y s i s o f b e a c h sand f r o m t h e f o l l o w i n g l o c a l i t i e s : B o u l t b e e ' s Beach, C a u l f e i l d Beach, E a s t Beach, the mouth o f G a p i l a n o R i v e r , Second Beach, K i t s i l a n o Beach and. U n i v e r s i t y Beach, These b e a c h e s a r e w i d e l y s e p a r a t e d , and g r e a t l e n g t h s o f s h o r e i n t e r v e n e whose sands have not been examinedo T h e r e -f o r e , i t c a n not y e t be d e t e r m i n e d . w h e t h e r the m i n e r a l c o n t e n t o f the b e a c h sands i n the v i c i n i t y o f V a n c o u v e r show a d i s -t i n c t l a t e r a l v a r i a t i o n . B e f o r e the r e s u l t s o f the m i n e r a l a n a l y s i s o f t h e sands c a n be c o r r e c t l y i n t e r p r e t e d , a s t u d y must be made o f the t i d e s , s h o r e c u r r e n t s and t h e p e t r o l o g y o f t h e s u r r o u n d i n g o u t c r o p s o f r o c k s , Because o f t h e l a c k o f t i m e and d a t a , t h e work r e c o r d e d h e r e i s c o n f i n e d t o t h e i d e n t i f i c a t i o n o f the c o n s t i t u e n t m i n e r a l s . -2-PTTRODUCTIOIT The a r e a i n the v i c i n i t y o f V a n c o u v e r i s c h a r a c t e r -i s e d by the development o f two d i s t i n c t p h y s i o g r a p h i c t y p e s -l o w l a n d and h i g h l a n d . The g e n e r a l l o w l a n d a r e a e x t e n d s f r o m the I n t e r n a t i o n a l Boundary to t h e n o r t h s h o r e o f B u r r a r d I n l e t . I t i s bounded on the n o r t h by the m o u n t a i n s o f the C o a s t Range, and on the e a s t by t h e C a s c a d e s . The monotony o f the l o w l a n d t o p o g r a p h y i s b r o k e n by t h r e e r e l a t i v e l y h i g h a r e a s o f g r o u n d - B u r r a r d p e n i n s u l a , Boundary U p l a n d and Point-R o b e r t s U p l a n d * The B u r r a r d p e n i n s u l a l i e s between B u r r a r d I n l e t and the n o r t h arm o f the F r a s e r River« T h i s a r e a i s d i v i d e d i n t o two r i d g e s w h i c h a r e s e p a r a t e d i n the west by F a l s e Creek v a l l e y , and i n the e a s t by t h e v a l l e y s o f S t i l l C r e e k and B r u n e t t e R i v e r * The r i d g e s a r e composed o f b e d r o c k , g l a c i a l d r i f t , i n t e r g l a c i a l sand and c l a y and r e c e n t marine and d e l t a d e p o s i t s * G e o l o g i c a l l y s p e a k i n g , a l l the r o c k s o f t h e l o w l a n d a r e young. The o l d e s t r o c k s i n t h e r e g i o n a r e the T e r t i a r y s e d i m e n t a r i e s . They c o n s i s t o f f a i r l y w e l l c o n s o l i d a t e d c o n -g l o m e r a t e s , s a n d s t o n e s and s h a l e s w h i c h have been downwarped and f a u l t e d , t h e n u p l i f t e d and e r o d e d . The P r o s p e c t P o i n t e r u p t i v e s a r e r e p r e s e n t e d by b a s i c dyke s, s i l l s , f l o w s and t u f f s . The age o f t h e s e v o l c a n i c s i s p o s t - E o c e n e and p r e - P l e i s t o c e n e . They t h e r e f o r e f u r n i s h e d some o f t h e m a t e r i a l f o r t h e g l a c i a l d e p o s i t s . -3-The P l e i s t o c e n e d e p o s i t s a r e v a r i e d i n c h a r a c t e r . U n c o n s o l i d a t e d g l a c i a l g r a v e l , s a n d s , s i l t s and c l a y s c o m p r i s e the g r e a t e r p a r t o f the s e d i m e n t s . However, i n t e r b e d d e d w i t h t h e s e a r e some i n t e r g l a c i a l s a n d s , s i l t s and c l a y s . The h i g h l a n d n o r t h o f B u r r a r d I n l e t i s composed o f the J u r a s s i c p l u t o n i c s o f t h e C o a s t Range B a t h o l i t h . The nar r o w s t r i p o f l o w l a n d a r e a t h a t i n t e r v e n e s between t h e mountains and t h e s h o r e i s due to t h e d e p o s i t i o n o f T e r t i a r y s a n d s t o n e , g l a c i a l d r i f t and t h e d e l t a s o f C a p l l a n o R i v e r , L y n n C r e e k and Seymour C r e e k . LABORATORY METHODS The o u t l i n e o f the l a b o r a t o r y methods employed has been i n c l u d e d i n the hope t h a t i t may be o f use i n any s i m i l a r work u n d e r t a k e n i n t h e f u t u r e . About two pounds o f sand were c o l l e c t e d a t low t i d e f r o m each b e a c h . C l e a n sand was o b t a i n e d by s c r a p i n g away s e v e r a l i n c h e s o f s u r f a c e m a t e r i a l . A p l a c e on t h e b e a c h was c h o s e n where t h e r e was not 1 i k e l y t o be a n a r t i f i c i a l c o n c e n -t r a t i o n o f heavy m i n e r a l s b y s u r f a c e i r r e g u l a r i t i e s o r p e c u l i a r wave a c t i o n . A f t e r t h e sand had been t h o r o u g h l y d r i e d , i t was put t h r o u g h a f o u r t e e n - m e s h s c r e e n to remove any l a r g e r o c k f r a g -ments o r s h e l l s . T h r e e t w e n t y - f i v e gram specimens were o b t a i n e d b y c o n i n g and q u a r t e r i n g , and each o f t h e s e was t r e a t e d s e p a r a t e l y i n o r d e r t h a t the r e s u l t s might be compared. The c a r b o n a t e s , m o s t l y s h e l l m a t e r i a l , were removed by s o a k i n g t h e sand i n d i l u t e h y d r o c h l o r i c a c i d . The p e r c e n t -age was c a l c u l a t e d f r o m the l o s s i n weight by t h e sand. Bromoform, w h i c h has a s p e c i f i c g r a v i t y o f 2.9. p r o v e d a s a t i s f a c t o r y medium f o r c o n c e n t r a t i n g the heavy m i n e r a l s . About 2J50 c c . o f t h i s l i q u i d was p o u r e d i n t o a o n e - l i t e r g l a s s s e p a r a t i n g f u n n e l , and t h e d r y sand was s l o w l y added. The f u n n e l was s t o p p e r e d , and the m i x t u r e a l l o w e d to s t a n d f o r an h o u r w i t h o u t d i s t u r b a n c e . The heavy m i n e r a l s , w h i c h had s e t t l e d to the b o t t o m o f t h e f u n n e l , were t h e n drawn o f f . S i n c e the f i r s t s e p a r a t i o n i s not always c o m p l e t e , the c o n t e n t s o f the f u n n e l were s t i r r e d and 20 c . c . o f bromoform added. When the r e m a i n i n g heavy m i n e r a l s had been c o m p l e t e l y p r e c i p i t a t e d , t h e y were d r a i n e d i n t o the b e a k e r c o n t a i n i n g the f i r s t c r o p . The l i g h t m i n e r a l s were washed from t h e f u n n e l w i t h bromoform. The l i g h t and heavy c r o p s were c a r e f u l l y washed, d r i e d and w e i g h e d . The m a g n e t i c m a t e r i a l was removed f r o m the heavy c o n c e n t r a t e w i t h a s m a l l h o r s e - s h o e magnet. The m i c r o s c o p e was u s e d to i d e n t i f y t h e m i n e r a l s . The l i g h t and h e a v y c r o p s were examined s e p a r a t e l y . The a g g l o m e r a t i o n o f m i n e r a l s was s p r e a d out on w h i t e p a p e r u n d e r the b i n o c u l a r s , and t h e g r a i n s i n g l e d out f o r i d e n t i f i c a t i o n was removed on the t i p o f a c a m e l * s - h a i r b r u s h to a g l a s s s l i d e f o r e x a m i n a t i o n u n d e r the m i c r o s c o p e w i t h a low o r medium-power l e n s . The g r a i n was t h e n c r u s h e d , and. t h e f r a g -ments s p r e a d o v e r t h r e e o r f o u r g l a s s s l i d e s . The r e f r a c t i v e i n d e x o f the m i n e r a l was d e t e r m i n e d by i m mersion i n o i l s o f d i f f e r e n t r e f r a c t i v e i n d i c e s . The o t h e r o p t i c a l p r o p e r t i e s o f the m i n e r a l were a l s o o b t a i n e d . E v e n v e r y minute f l a k e s o f m i n e r a l s y i e l d e d c l e a r i n t e r f e r e n c e f i g u r e s . B e f o r e some o f t h e g r a i n s were examined u n d e r the m i c r o s c o p e , t h e y were dr o p p e d i n t o a b e a k e r o f methylene i o d i d e w h i c h has a s p e c i f i c g r a v i t y o f J . J . T h e r e f o r e a c l o s e r a p p r o x i m a t i o n t o t h e s p e c i f i c g r a v i t y o f t h e m i n e r a l was obtained.. However, t h i s s t e p u s u a l l y p r o v e d s u p e r f l u o u s . A m i c r o m e t e r e y e - p i e c e and a medium-power l e n s were u s e d to e s t i m a t e t h e s i z e o f t h e m i n e r a l g r a i n s . - 6 -The p e r c e n t a g e c o m p o s i t i o n o f the sand, was computed by c o u n t i n g , The m i n e r a l s were s p r e a d on s l i d e s , and examined under a low-power l e n s . The a v e r a g e o f s e v e r a l f i e l d s was t a k e n as t h e r e s u l t , I n e s t i m a t i n g the p e r c e n t a g e c o m p o s i t i o n , t h e s i z e o f t h e m i n e r a l g r a i n s was t a k e n i n t o c o n s i d e r a t i o n . To AZCOMF-ANY THESIS BY PHYLLIS Le.en/s VANCOUVERAHD VICINITY P.£GL. I936\ -7-Chapter I I THE MINEBALOGY O F THE SANDS The following is a summary o f the m i n e r a l o g y of the 'sands which have been analysed*, The numbers assigned to the beaches correspond to those found on t h e accompanying map. The constituents of the light and heavy mineral crops are l i s t e d under t h e i r respective headings, and the minerals are b r i e f l y described. 1 . Boultbee *s Beach Boultbee*s Beach i s situated on the eastern side of a narrow p o i n t of Jurassic i g n e o u s rocks, which j u t s into Burrard Inlet southeast of Horseshoe Bay, A . P e r c e n t a g e , by weight, of carbonates: 4% B, Percentage , by weight, o f heavy minerals: 7 % G« Heavy Minerals Epidote {13% ~ by c o u n t i n g ) H o r n b l e n d e (10% - by cou n t I n g ) Hypersthene . Z i r c o n G a r n e t Tremolite B i o t i t e Pyrite 1 Magnetite (2% - by weight) \ The heavy minerals are of two di s t i n c t sizes. One •half o f them have an average d i a m e t e r of .4 mm., and t h e rest have an average d i a m e t e r of . 1 mm. The largest grains of epidote a r e pale g r e e n to white, s u g a r y and rounded« The s m a l l g r a i n s are clear, b r i g h t Fl G URE I -8-g r e e n p r i s m s , and may e a s i l y be m i s t a k e n f o r olivine® The h o r n b l e n d e o c c u r s as g l o s s y b l a c k p r i s m s . The s m a l l b r o w n i s h - g r e e n p r i s m s o f h y p e r s t h e n e a r e d i s t i n c t l y p l e o c h r o i c i n p i n k and g r e e n tones,, S e v e r a l minute c r y s t a l s o f brown z i r c o n were found® A number o f p a l e y e l l o w and c o l o r l e s s f r a g m e n t s were a l s o i d e n t i f i e d a s t h i s m i n e r a l . G a r n e t s a r e rare» They a r e brown and opaque w i t h rough s u r f a c e s . The t r e m o l i t e p r i s m s a r e dark g r a y i s h - g r e e n . A few o f the b i o t i t e f l a k e s show a g r e e n t i n g e . The p y r i t e f r a g m e n t s a r e a n g u l a r . D« L i g h t M i n e r a l s Q u a r t z (95% -• by c o u n t i n g ) F e l d s p a r s Rock f r a g m e n t s The l i g h t m i n e r a l s , w h i c h a r e u n i f o r m i n s i z e , have an a v e r a g e d i a m e t e r o f .j? mm. 2. C a u l f e i l d Beach G a u l f e i l d Beach l i e s i n a s h a l l o w bay about one-t h i r d o f a m i l e e a s t o f P o i n t A t k i n s o n . The denuded r o c k s o f -the C a u l f e i l d f o r m a t i o n d i p s t e e p l y i n t o t h e s a n d s . A. P e r c e n t a g e , by w e i g h t , o f c a r b o n a t e s : 2% B. P e r c e n t a g e , by w e i g h t , o f heavy m i n e r a l s : 5% -9 -C. Heavy M i n e r a l s E p i d o t e (33% - by c o u n t i n g } H o r n b l e n d e (20> - by c o u n t i n g ) B i o t i t e G a r n e t V o l c a n i c G l a s s P y r i t e C h r o m i t e M a g n e t i t e (2% - by w e i g h t ) T o u r m a l i n e ? The heavy m i n e r a l s have an av e r a g e d i a m e t e r o f .4 mm. The g r a i n s o f e p i d o t e and h o r n b l e n d e have t h e same c h a r a c t e r i s t i c s a s t h o s e o c c u r r i n g i n the sand o f B o u l t b e e f s Beach. Some o f the b i o t i t e f l a k e s a r e g r e e n . The g a r n e t s a r e brown, opaque and w e l l r o u n d e d . V o l c a n i c g l a s s i s r a r e r I t i s c o n s p i c u o u s because o f the i r r e g u l a r o u t l i n e o f the f r a g m e n t s . The p y r i t e f r a g m e n t s a r e a n g u l a r . The c h r o m i t e g r a i n s a r e ro u n d e d . One deep g r e e n g r a i n o f sand was d o u b t f u l l y i d e n t i -f i e d as t o u r m a l i n e , D, l i g h t M i n e r a l s Q u a r t z (93% - by c o u n t i n g ) F e l d s p a r s P h l o g o p i t e Rock f r a g m e n t s The a v e r a g e d i a m e t e r o f t h e l i g h t m i n e r a l s i s *3 mm. Most o f the q u a r t z g r a i n s a r e rounded. Some o f them a r e p a l e y e l l o w . The f e l d s p a r f r a g m e n t s a r e a n g u l a r . -10 « 3. E a s t Beach E a s t Beach b o r d e r s the l o w - l y i n g s t r i p o f g l a c i a l outwash and i n t e r g l a c i a l d e p o s i t s w h i c h l i e to the e a s t o f the West Va n e o a v e r F e r r y w h a r f . A. P e r c e n t a g e , by w e i g h t , o f c a r b o n a t e : 3% B, P e r c e n t a g e , by w e i g h t , o f heavy m i n e r a l s : 7°/° C, Heavy M i n e r a l s E p i d o t e (30% - by c o u n t i n g ) H o r n b l e n d e (30> " hy c o u n t i n g ) H y p e r s t h e n e Garnet M a g n e t i t e (12% - by w e i g h t ) The heavy m i n e r a l s have an a v e r a g e d i a m e t e r o f .7 mm. The e p i d o t e g r a i n s a r e ro u n d e d . The h o r n b l e n d e p r i s m s o f t e n show an a l t e r a t i o n to a mic a c e o u s s u b s t a n c e . B r o w n i s h - g r e e n h y p e r s t h e n e p r i s m s a r e r a r e . The g a r n e t s show no c r y s t a l f o r m . They a r e e i t h e r brown and opaque o r p a l e p i n k and t r a n s p a r e n t , . D. l i g h t M i n e r a l s Q u a r t z ' ( 7 5 % - by c o u n t i n g ) F e l d s p a r s P h l o g o p i t e Book f r a g m e n t s The l i g h t m i n e r a l s have an aver a g e d i a m e t e r o f .8 mm. The q u a r t z g r a i n s a r e c o l o r l e s s , w h i t e o r y e l l o w . The f e l d s p a r f r a g m e n t s a r e a n g u l a r . P h l o g o p i t e i s r a r e * FIGURE X 4. The Mouth o f O a p i l a n o R i v e r T h i s sample o f sand was t a k e n from the d e l t a o f t h e O a p i l a n o R i v e r w h i c h c u t s t h r o u g h b o t h J u r a s s i c and T e r t i a r y rocks» A. P e r c e n t a g e , by w e i g h t , o f c a r b o n a t e s t 8% B. P e r c e n t a g e , by w e i g h t , o f heavy m i n e r a l s : 10% C s Heavy M i n e r a l s H o r n b l e n d e (60% - by c o u n t i n g E p i d o t e (20% - by c o u n t i n g . H y p e r s t h e n e {3% - by c o u n t i n g ) B i o t i t e G a r n e t Z i r c o n T r e m o l i t e P y r i t e M a g n e t i t e (20% - by w e i g h t ) The heavy m i n e r a l s a r e o f two s i z e s . Some o f the g r a i n s have an a v e r a g e d i a m e t e r o f «1 mmt, w h i l e o t h e r s have an a v e r a g e d i a m e t e r o f «J? mm0 The p r i s m s o f h o r n b l e n d e .are s h i n y and a n g u l a r . The e p i d o t e v a r i e s from c o m p a r a t i v e l y l a r g e , rounded g r a i n s to minute p r i s m s . The h y p e r s t h e n e c r y s t a l s a r e o l i v e g r e e n p r i s m s . They a r e p l e o c h r o i c * Many o f them a r e c o a t e d w i t h a r e d a l t e r a t i o n p r o d u c t w h i c h makes i d e n t i f i c a t i o n d i f f i c u l t . The b i o t i t e f l a k e s are e i t h e r b l a c k o r g r e e n . A few rough brown g a r n e t s a r e p r e s e n t , but the g r e a t e r number a r e m i c r o s c o p i c , p i n k d o d e c a h e d r o n s . The minute z i r c o n c r y s t a l s a r e salmon p i n k . They a p p e a r amongst the o t h e r sand g r a i n s l i k e p i n - p o i n t s o f l i g h t . T r e m o l i t e i s r a r e . I t o c c u r s as g r e y - g r e e n p r i s m s . -12-The p y r i t e f r a g m e n t s a r e v e r y much worn and p i t t e d . D. l i g h t M i n e r a l s ' Q u a r t z (15% ~ hy c o u n t i n g ) F e l d s p a r s ( 2 0 % - hy c o u n t i n g ) P h l o g o p i t e Rock f r a g m e n t s The l i g h t m i n e r a l s have an a v e r a g e d i a m e t e r o f .j? mm, The q u a r t z g r a i n s a r e e i t h e r c o l o r l e s s or w h i t e . The f e l d s p a r f r a g m e n t s a r e a n g u l a r . 3= Second Beach The sand was o b t a i n e d at t h e promontory w h i c h forms the w e s t e r n boundary o f Second Beach. The B u r r a r d f o r m a t i o n o u t c r o p s h e r e , and the s u r f a c e o f t h e l a n d i s c o v e r e d by a mantle o f g l a c i a l t i l l . A. P e r c e n t a g e , by w e i g h t , o f c a r b o n a t e : 4% Bo P e r c e n t a g e , by weight . o f heavy m i n e r a l s : 1% • C a Heavy M i n e r a l s E p i d o t e (4-3% - by c o u n t i n g ) H o r n b l e n d e (43% ~ hy c o u n t i n g ) G a r n e t H y p e r s t h e n e B i o t i t e . R u t i l e The heavy m i n e r a l s have an a v e r a g e d i a m e t e r o-f .4 mm. The e p i d o t e and h o r n b l e n d e g r a i n s were both s l i g h t l y rounded« M i n u t e p i n k g a r n e t s a r e r a r e . - H y p e r s t h e n e i s a l s o rare» I t i s e i t h e r g r e e n i s h -brown o r c o a t e d w i t h a r e d mineral® The b i o t i t e i s b l a c k One g r a y i s h - b r o w n c r y s t a l o f r u t i l e was founds D. l i g h t M i n e r a l s Q u a r t z F e l d s p a r s Hock f r a g m e n t s (75% " by c o u n t i n g (157° ~ by c o u n t i n g The a v e r a g e d i a m e t e r o f t h e l i g h t m i n e r a l s i s .j? mm. S e v e r a l s m a l l , c l e a r q u a r t z c r y s t a l s were i d e n t i f i e d . The c o l o r l e s s q u a r t z g r a i n s f r o m t h i s b e a c h a r e e x c e p t i o n a l l y t r a n s p a r e n t o Most o f the f e l d s p a r g r a i n s a r e c o l o r l e s s and a n g u l a r = 6. K i t s i l a n o Beach T h i s sample o f sand was t a k e n from the p o i n t w h i c h marks t h e n o r t h e r n l i m i t o f K i t s i l a n o Beacho D e l t a and a l l u v i a l d e p o s i t s s u r r o u n d the b e a c h , and t h e K i t s i l a n o forma-t i o n o u t c r o p s to t h e w e s t . A P e r c e n t a ; g e , by w e i g h t , o f c a r b o n a t e s : 2.5% B. P e r c e n t a g e , by w e i g h t , o f heavy m i n e r a l s : G. Heavy M i n e r a l s M a g n e t i t e (1% - by w e i g h t ) The heavy m i n e r a l s have an a v e r a g e d i a m e t e r o f .7 mm. The e p i d o t e and h o r n b l e n d e g r a i n s a r e w e l l rounded* The p r i s m s o f h y p e r s t h e n e a r e s m a l l and o l i v e g r e e n . Z i r c o n o c c u r s e i t h e r as r e d d i s h - b r o w n p r i s m s o r as minute c o l o r l e s s c r y s t a l s > The f r a g m e n t s o f g a r n e t a r e e i t h e r p a l e p i n k o r browno D. l i g h t M i n e r a l s Q u a r t z (95% ~ hy c o u n t i n g ) F e l d s p a r s Rock f r a g m e n t s The l i g h t m i n e r a l s have an a v e r a g e d i a m e t e r o f .9 mm. The q u a r t z g r a i n s a r e c o l o r l e s s , m i l k y o r y e l l o w i s h . F e l d s p a r f r a g m e n t s a r e r a r e . 7. U n i v e r s i t y Beach U n i v e r s i t y Beach l i e s a t t h e base o f the p r e c i p i t o u s c l i f f s o f P o i n t Grey« T h i s w e s t e r n e x t r e m i t y o f B u r r a r d pen-i n s u l a i s composed o f g l a c i a l outwash and i n t e r g l a c i a l d e p o s i t s . A . P e r c e n t a g e , by w e i g h t , o f c a r b o n a t e : 4% B. P e r c e n t a g e , by w e i g h t , o f heavy m i n e r a l s : 11% C. Heavy M i n e r a l s E p i d o t e (30% - by c o u n t i n g ) H o r n b l e n d e (30% - by c o u n t i n g ) H y p e r s t h e n e (25% - by c o u n t i n g ) G a r n e t (5% ~ hy c o u n t i n g ) Z i r c o n (1% - by c o u n t i n g ) A p a t i t e B i o t i t e -15-M u s c o v i t e M a g n e t i t e (13% - by w e i g h t ) The a v e r a g e d i a m e t e r o f t h e heavy m i n e r a l s i s ,4 mm. Most o f the e p i d o t e g r a i n s a r e rounded and s u g a r y , but some a r e i n t h e f o r m o f t r a n s p a r e n t g r e e n p r i s m s . The h o r n b l e n d e p r i s m s a r e d e f i n i t e l y a n g u l a r . Many o f t h e h y p e r s t h e n e c r y s t a l s a r e a l m o s t complete-l y a l t e r e d t o a r e d m i n e r a l . T h i s sand i s c h a r a c t e r i s e d by r e d d i s h - b r o w n d o d e c a -h e d r o n s o f garnet« A few f r a g m e n t s o f p a l e p i n k g a r n e t a r e a l s o i n t e r s p e r s e d amongst the heavy minerals« Z i r c o n g r a i n s a r e e i t h e r brown, y e l l o w o r p i n k . The l a t t e r c o l o r i s u s u a l l y f o u n d i n minute p r i s m a t i c crystals® The p a l e b l u i s h - g r e e n a p a t i t e g r a i n s a r e rounded. B i o t i t e and m u s c o v i t e a r e r a r e . D« L i g h t M i n e r a l s Q u a r t z (15% ~ hy c o u n t i n g ) F e l d s p a r s ( 2 0 % - by c o u n t i n g ) E o c k f r a g m e n t s • The a v e r a g e d i a m e t e r o f t h e l i g h t m i n e r a l s i s .6 mm. The q u a r t z g r a i n s v a r y i n s i z e and shape and a r e e i t h e r w h i t e , c o l o r l e s s o r p i n k . The f e l d s p a r f r a g m e n t s a r e a n g u l a r . 1^ =0 is, ~1 ^ ^ 1 < X ^ 2 5 ri o ^ 5 I x 1 to 2 M l b O) < < < X < < X ® ® 8) X X X < < X < X X < < X ® ® ® X X X X X ® X X X < X < < < < < ® < < < < < < X X < /I /°/) 77 775 A/an r£ CHROrllTE-£ PI DOTE FELDSPAR &A R N E T HORNBLENDE HYPERS THEN £ MACrNETI TE MUSCOVIT E PHL OO-OPITE PYRITE QUARTZ. PUTILE TRENOLITE TOURMALINE VESLIV/ANITE VOLCANSC OLASS ZIRCON —16— C h a p t e r I I I CONCLUSION The sands o f the beach e s i n the v i c i n i t y o f V a n c o u v e r have been d e r i v e d f r o m two d i s t r i b u t i v e p r o v i n c e s -the s e d i m e n t a r y l o w l a n d and the h i g h l a n d o f the Coast Range» T h e r e f o r e , some o f the m i n e r a l s owe t h e i r o r i g i n t o the r e -d e p o s i t i o n o f p r e - e x i s t i n g s e d i m e n t s , w h i l e o t h e r s r e p r e s e n t t h e d i s i n t e g r a t i o n o f i g n e o u s r o c k s * The beaches o f t h e n o r t h shore o f B u r r a r d I n l e t l i e a t the f o o t o f t h e m o u n t a i n s , and t h o s e o f the s o u t h s h o r e b o r d e r the s e d i m e n t a r y l o w l a n d . The accompanying t a b l e (.Fig. 3 ) w h i c h r e c o r d s t h e r e s u l t s o f the a n a l y s e s , demon-s t r a t e s the f a c t t h a t t h e sands o f the v a r i o u s beaches d i f f e r o n l y i n t h e r e l a t i v e p r o p o r t i o n s o f the m i n e r a l c o n s t i t u e n t s . The s i m i l a r i t y i n the m i n e r a l c o n t e n t o f the sands may be e x p l a i n e d , by the f a c t t h a t t h e r o c k s o f the Coast Range were l a i d b a r e by T e r t i a r y and P l e i s t o c e n e e r o s i o n , and t h e r e f o r e a c t e d as a d i s t r i b u t i v e p r o v i n c e f o r the T e r t i a r y and P l e i s t o -cene s e d i m e n t s o f w h i c h the l o w l a n d i s composed. Hence, upon e r o s i o n , t h e s e d i m e n t a r y f o r m a t i o n s o f the l o w l a n d and t h e i g n e o u s r o c k s o f the h i g h l a n d y i e l d t h e same m i n e r a l s . The m i n e r a l s o f t h e g l a c i a l d e p o s i t s have undergone v e r y l i t t l e a l t e r a t i o n b e c a u s e they were a c c u m u l a t e d a t a time when c h e m i c a l w e a t h e r i n g was a t a minimum. E p i d o t e and h o r n b l e n d e , w h i c h a r e t h e most abundant o f the heavy m i n e r a l s , o c c u r i n v a r y i n g p r o p o r t i o n s i n t h e -17-d i f f e r e n t b e a ch sands. From the b l o c k d i a g r a m ( F i g . H ) i t may-be s e e n t h a t t h e p e r c e n t a g e o f e p i d o t e i n the sands o f the n o r t h s h o r e d e c r e a s e s s t e a d i l y f r o m B o u l t b e e T s Beach e a s t w a r d to the mouth o f the C a p i l a n o R i v e r , whereas the p e r c e n t a g e o f * h o r n b l e n d e i n c r e a s e s i n t h i s d i r e c t i o n . B o t h e p i d o t e and h o r n b l e n d e a r e a b u n d a n t l y d i s s e m i n -a t e d t h r o u g h o u t the r o c k s o f the Coast Range B a t h o l i t h . E p i d o t e dykes c u t the r o c k s w h i c h l i e a l o n g t h e s h o r e e a s t o f C a u l f e i l d . and v e i n l e t s and masses o f t h i s m i n e r a l o c c u r i n L y n n and C a p i l a n o V a l l e y s . H o r n b l e n d e i s an i m p o r t a n t c o n s t i -t u e n t o f the C a u l f e i l d f o r m a t i o n , as w e l l as o f t h e e p i d o t e i dykes m e n t i o n e d above. A c c o r d i n g t o Burwash , h o r n b l e n d e i s t h e p r i n c i p a l f e r r o m a g n e s i a n m i n e r a l i n a "dark g r e e n , m a s s i v e p o r p h y r i t e " w h i c h o u t c r o p s i n the v a l l e y o f the C a p i l a n o R i v e r . The e r o s i o n o f t h i s p o r p h y r i t e a c c o u n t s f o r the h i g h p e r c e n t a g e o f h o r n b l e n d e i n the sand o f the d e l t a o f the C a p i l a n o R i v e r . The number o f samples a n a l y s e d from the s o u t h s h o r e o f B u r r a r d I n l e t was not s u f f i c i e n t t o show any p e r s i s t e n t l a t e r a l v a r i a t i o n i n the p e r c e n t a g e s o f h o r n b l e n d e and e p i d o t e . These m i n e r a l s b o t h o c c u r i n the t u f f s w h i c h a r e exposed on the s o u t h s i d e o f F a l s e C r e e k . .Many o f the f r e s h , a n g u l a r f r a g m e n t s o f e p i d o t e and h o r n b l e n d e have p r o b a b l y been d e r i v e d f r o m t h i s s o u r c e . H o r n b l e n d e i s a l s o p l e n t i f u l i n the P r o s p e c t P o i n t e r u p t i v e s . M a g n e t i t e , which i s a common c o n s t i t u e n t o f many 1. Bur-wash, E.M.J. - The Geology o f V a n c o u v e r and V i c i n i t y . 1918. p. 35 • - 1 8 -t y p e s o f r o c k , i s p r e s e n t i n a p p r e c i a b l e amounts i n a l l the sand a n a l y s e d e x c e p t t h a t o f Second Beach* The sand o f Second Beach i s a l s o c h a r a c t e r i s e d by h a v i n g the l o w e s t p e r c e n t a g e o f heavy m i n e r a l s . The r e s u l t s show t h a t the g r e a t e s t p e r c e n t -, ages o f m a g n e t i t e o c c u r i n t h o s e sands which have the h i g h e s t p e r c e n t a g e s o f h e a v y m i n e r a l s . A l l the b e a c h sands a n a l y s e d c o n t a i n l a r g e amounts o f q u a r t z w h i c h commonly o c c u r s as v a r i o u s c o l o r e d , rounded g r a i n s o r a n g u l a r f r a g m e n t s . However, s e v e r a l s m a l l q u a r t z c r y s t a l s were f o u n d i n the sand from Second Beach. These p r o b a b l y o r i g i n a t e d i n the v e s i c u l a r c a v i t i e s o f the P r o s p e c t P o i n t dyke• The metamorphosed l i m e s t o n e o f L y n n Creek i s u n d o u b t e d l y t h e s o u r c e o f many o f the g a r n e t s . However, the dod e c a h e d r o n s o f g a r n e t from the mouth o f O a p i l a n o R i v e r a r e p a l e p i n k , w h i l e t h o s e from U n i v e r s i t y Beach a r e r e d d i s h brown and l a r g e r . T h e r e f o r e , t h e r e must be more t h a n one i m p o r t a n t s o u r c e o f g a r n e t . S i n c e h y p e r s t h e n e i s a common metamorphic m i n e r a l , i t s p r e s e n c e i n the sands i s not u n u s u a l . The c r y s t a l s o f h y p e r s t h e n e f r o m the sand o f O a p i l a n o d e l t a show l e s s a l t e r a -t i o n t h a n t h o s e from the o t h e r b e a c h e s . T h e r e f o r e , i t seems p r o b a b l e t h a t t h e s o u r c e o f h y p e r s t h e n e l i e s w i t h i n the a r e a d r a i n e d by O a p i l a n o R i v e r . C h r o m i t e was f o u n d o n l y i n t h e sand o f C a u l f e i l d B each. The o l i v i n e - b e a r i n g dykes w h i c h cut t h e C a u l f e i l d . f o r m a t i o n a r e a l i k e l y s o u r c e o f t h e c h r o m i t e g r a i n s . V o l c a n i c g l a s s i s a n o t h e r m i n e r a l w h i c h was f o u n d -19 -o n l y i n the sand o f C a u l f e i l d Beach. The p o s t - E o c e n e e r u p -t i v e s o f Howe Sound a r e c h a r a c t e r i s e d by brown g l a s s . T h e i r e r o s i o n o f f e r s a p l a u s i b l e e x p l a n a t i o n f o r the p r e s e n c e o f t h e g l a s s i n the C a u l f e i l d s a n d. The r e s t o f t h e m i n e r a l s r e c o r d e d i n t h e t a b l e o f m i n e r a l o c c u r r e n c e s a r e p r e s e n t i n t h e sands i n s m a l l amounts, and as y e t t h e i r c h a r a c t e r i s t i c s have not p r o v e d i n d i c a t i v e o f t h e i r source® However, i t i s the r a r e heavy m i n e r a l s w i t h a r e s t r i c t e d r ange w h i c h a r e most u s e f u l i n t h e c o r r e l a t i o n o f s e d i m e n t s . T h e r e f o r e , none o f t h e c o n s t i t u e n t m i n e r a l s o f t h e sands s h o u l d be c l a s s e d as u n i m p o r t a n t u n t i l more a n a l y s e s have been made, and the p e t r o l o g y o f t h e d i s t r i b u t i v e p r o v -i n c e s has been more c o m p r e h e n s i v e l y s t u d i e d . The d e t r i t a l m i n e r a l s y i e l d i n f o r m a t i o n i n r e g a r d to t h e s o u r c e o f t h e s e d i m e n t s , t h e d i r e c t i o n o f d r a i n a g e and t h e c o n d i t i o n s o f t r a n s p o r t . The movements o f the sea-bed and the s u b s i d e n c e o r e l e v a t i o n o f t h e l and-masses a r e a l s o r e f l e c t e d i n t h e m i n e r a l c o m p o s i t i o n o f the s h o r e s a n d s . • The a n a l y s e s w h i c h a r e the b a s i s o f t h i s r e p o r t a r e m e r e l y a p r e l i m i n a r y e f f o r t to d i s c l o s e the n a t u r a l h i s t o r y o f t h e sands by d e t e r m i n i n g t h e q u a l i t a t i v e d i s t r i b u t i o n o f the m i n e r a l s and the v a r i a t i o n i n the p r o p o r t i o n s o f the c o n s t i t u -ent m i n e r a l s as the d e p o s i t s a r e t r a c e d l a t e r a l l y . Hence i t i s c l e a r t h a t much c a r e f u l work r e m a i n s t o be done on t h e sands i n the v i c i n i t y o f V a n c o u v e r b e f o r e any r e s u l t s can be o f f e r e d as a c o n t r i b u t i o n t o t h e s c i e n c e o f g e o l o g y . BIBLIOGRAPHY B o s w e l l , P.G.Ho On t h e M i n e r a l o g y o f S e d i m e n t a r y Rocks. London, 1933« M i l n e r , Henry B, S e d i m e n t a r y P e t r o g r a p h y . London, 1929® J o h n s t o n , W.A. G e o l o g y "of the F r a s e r R i v e r D e l t a Map A r e a , G.G.S. Memoir 133< Le Roy, 0»E« P r e l i m i n a r y R e p o r t on a P o r t i o n o f the M a i n Coast o f B r i t i s h Columbia and A d j a c e n t I s l a n d s e Ottawa, 1908. Burwash, Edward Moore J a c k s o n The Geology o f Vancouver and V i c i n i t y * C h i c a g o , 1918, 

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