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An interpretation of lithogeochemical data of the Guichon Creek batholith Tombale, Akolang Russia 1984

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1 * AN INTERPRETATION OF LITHOGEOCHEMICAL DATA OF THE GUICHON CREEK BATHOLITH by AKOLANG RUSSIA TOMBALE B.Sc. ( G e o l o g y ) U n i v e r s i t y o f I b a d a n , 1979. A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department o f G e o l o g i c a l S c i e n c e s We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d A *• THE UNIVERSITY OF BRITISH COLUMBIA J u l y 1984 c A k o l a n g R u s s i a Tombale, 1984. 06 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission f o r extensive copying of t h i s t h e s i s fo r s c h o l a r l y purposes may be granted by the head of my department or by h i s or her representatives. I t i s understood that copying or pub l i c a t i o n of t h i s t h e s i s fo r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of 7 ^ / 0 g<- c^aJ? ^Q/e^nCe^> ~ f : — 0 . The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date Ze/o!-./ t ¥ ABSTRACT The Guichon Creek b a t h o l i t h magma was emplaced along p r e - e x i s t i n g n o r t h - t r e n d i n g s t r u c t u r e s , s t i l l l a r g e l y molten. The emplacement of about 2000 km^ molten rock m a t e r i a l l e d to a surging inwards of m a t e r i a l at the centre of the b a t h o l i t h as evidenced by the saucer-shape of the b a t h o l i t h . The contact of hot rock m a t e r i a l with c o o l e r rocks l e d to c r y s t a l l i z a t i o n of magma from the margins inwards forming a c r y s t a l l i n e cover (Border phase) under which magma was s t i l l molten. Presence of the c r y s t a l l i n e cover reduced subsequent c r y s t a l l i z a t i o n r a t e , as evidenced by i n c r e a s e i n g r a i n s i z e towards younger phases. The inwards surging of magma towards the b a t h o l i t h centre cr e a t e d two dome-like s t r u c t u r e s with that of higher e l e v a t i o n to the no r t h . Due to e l e v a t i o n d i f f e r e n c e s c r y s t a l l i z a t i o n proceeded f a i r l y r a p i d l y at the northern end of the b a t h o l i t h . Magma s a t u r a t i o n occurred a f t e r c r y s t a l l i z a t i o n of Highland V a l l e y phase (about 72 percent c r y s t a l l i z a t i o n ) . An e v o l v i n g v o l a t i l e phase c o l l e c t e d beneath the northern dome s t r u c t u r e as evidenced by prevalence of b i o t i t e over hornblende i n Guichon v a r i e t y p r e v a l e n t i n the northern part of the b a t h o l i t h compared to Chataway v a r i e t y i n the south. I n t e r n a l pressure soon exceeded c o n f i n i n g pressure r e s u l t i n g i n r e l e a s e of v o l a t i l e f l u i d s through f r a c t u r i n g of cover rocks. Release of v o l a t i l e f l u i d s c r e a t e d lower i n t e r n a l p r e s s u r e s r e s u l t i n g i n i n c r e a s e d c r y s t a l l i z a t i o n r a t e a t the n o r t h e r n end w i t h the v o l a t i l e c e n t r e m i g r a t i n g s o u t h w a r d s t o w a r d s the se c o n d dome s t r u c t u r e where a second p e r i o d of v o l a t i l e r e l e a s e took p l a c e . a l l y zoned b a t h o l i t h r a n g i n g f r o m m a f i c u n i t s a t the mar g i n s to a c i d i c u n i t s a t the c o r e , t o o k p l a c e t h r o u g h c r y s t a l f r a c t i o n a t i o n c h a r a c t e r i z e d by t h e m i n e r a l assemblage p l a g i o c l a s e - b i o t i t e - h o r n b l e n d e . C r y s t a l f r a c t i o n a t i o n a l s o p l a y e d an i m p o r t a n t r o l e i n t h e d i s t r i b u t i o n of the a l k a l i and a l k a l i e a r t h m e t a l s Rb, Ba and S r , i n o l d e r u n i t s of the b a t h o l i t h . B u l k d i s t r i b u t i o n c o e f f i c i e n t s (D) show t h a t Ba and Sr were p r e f e r e n t i a l l y p a r t i t i o n e d i n t o e a r l y formed s o l i d s s i n c e t h e i r D v a l u e s e x c e e d e d one, whereas Rb w i t h D v a l u e s l e s s t h a n one led to c o n c e n t r a t i o n i n r e s i d u a l m e l t s . However, an i n c r e a s e i n K/Rb r a t i o i n you n g e r phases i n d i c a t e s t h a t i n g e n e r a l , Rb d e c r e a s e d w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n . T h i s K/Rb r a t i o t r e n d i s a t t r i b u t e d to p r e f e r e n t i a l p a r t i t i o n i n g o f Rb t o w a r d s v o l a t i l e f l u i d s , i n c o n t r a s t w i t h p o t a s s i u m . i n t e r e s t i n g d i s t r i b u t i o n p a t t e r n s . D v a l u e s f o r t h e s e e l e m e n t s a r e more t h a n one i n o l d e r phase and f a l l below one i n younger p h a s e s . C r y s t a l f i e l d t h e o r y p r e d i c t s t h a t t h e s e e l e m e n t s would be p a r t i t i o n e d to e a r l y formed s o l i d s d u r i n g c r y s t a l l i z a t i o n of s i l i c a t e magmas. D v a l u e s of t h e s e e l e m e n t s i n o l d e r p h a s e s s u g g e s t t h a t a c t u a l t r a c e e l e m e n t d i s t r i b u t i o n i s i n agreement w i t h t h e o r e t i c a l p r e d i c t i o n s . Low D v a l u e s d i f f e r e n t i a t i o n r e s u l t i n g i n t h e c o m p o s i t i o n -T r a n s i t i o n e l e m e n t s Cu, Co, C r , N i and Zn a l s o show iv ( l e s s t h a n one) i n younger phase c o n d i t i o n s i n d i c a t e s t h a t i n the p r e s e n c e o f a v o l a t i l e phase t h e s e e l e m e n t s a r e p a r t i t i o n e d p r e f e r e n t i a l l y t o w a r d s t h e s e f l u i d s , than c o e x i s t i n g s o l i d s . L i n e a r c o r r e l a t i o n c o e f f i c i e n t s and s c a t t e r d i a g r a m s f o r c o p p e r and c h l o r i n e i n a l l phases of the b a t h o l i t h show t h a t t h e s e e l e m e n t s a r e p a r t i t i o n e d p r e f e r e n t i a l l y i n t o a v o l a t i l e p h a s e . D i s t r i b u t i o n p a t t e r n s of t r a c e e l e m e n t s can be used to a s s e s s w h i c h o f t h e e l e m e n t s a r e p r e f e r e n t i a l l y t r a n s f e r r e d t o w a r d s an e v o l v i n g v o l a t i l e phase which c o o l t o form m i n e r a l i z i n g s o l u t i o n s . The t i m i n g a t w h i c h v o l a t i l e f l u i d s s e p a r a t e from t h e c r y s t a l l i z i n g s i l i c a t e magma can a l s o be e s t i m a t e d f r o m t r a c e e l e m e n t d i s t r i b u t i o n p a t t e r n s , w hich t o g e t h e r w i t h t h e knowledge of t h e a f f e c t e d e l e m e n t s form the b a s i s f o r o r e p o t e n t i a l e v a l u a t i o n of g r a n i t o i d p l u t o n s . i V ACKNOWLEDGEMENTS F i n a n c i a l a s s i s t a n c e f o r t h i s r e s e a r c h was p r o v i d e d by C a n a d i a n I n t e r n a t i o n a l D e v e l o p m e n t Agency ( C I D A ) . I am g r a t e f u l t o Dr. A . J . S i n c l a i r , my s u p e r v i s o r , w i t h o u t whose p a t i e n t g u i d a n c e and d i r e c t i o n t h i s work may n o t have been p o s s i b l e , and a l s o f o r ma k i n g my s t a y i n Canada memorable. G r a t i t u d e i s a l s o a c c o r d e d t o D r . W.J. M c M i l l a n who p r o v i d e d g e o l o g i c a l and a n a l y t i c a l d a t a f i l e s f o r t h e r e s e a r c h . Dr. M c M i l l a n a l s o p r o v i d e d t h e a u t h o r w i t h e x t e n s i v e d i s c u s s i o n and g u i d a n c e c o n c e r n i n g t h e G u i c h o n C r e e k b a t h o l i t h d u r i n g two e x t e n d e d f i e l d e x c u r s i o n s t o t h e H i g h l a n d V a l l e y d u r i n g t h e 1983 and 1984 f i e l d s e a s o n s . S p e c i a l t h a n k s t o A s g e r B e n t z e n who p a t i e n t l y p r o v i d e d much o f h i s c o m p u t e r t i m e t o h e l p w i t h d a t a a n a l y s i s . I am a l s o g r a t e f u l t o Mr. A. S h i r a n , CIDA c o o r d i n a t o r , and h i s a s s i s t a n t , M r s . C. Dawson, f o r t h e i r a s s i s t a n c e w i t h non a c a d e m i c m a t t e r s t h r o u g h o u t my s t a y i n Canada. v i TABLE OF CONTENTS A b s t r a c t i i Acknowledgements v T a b l e o f C o n t e n t s v i L i s t o f T a b l e s v i i i L i s t o f F i g u r e s ix C h a p t e r One: I n t r o d u c t i o n 1 C h a p t e r Two: C r y s t a l l i z a t i o n Model 4 A b s t r a c t 4 I n t r o d u c t i o n 6 G e o l o g i c S e t t i n g 6 Volume o f G u i c h o n B a t h o l i t h Magma 7 S t r u c t u r e 9 C o m p o s i t i o n Of The G u i c h o n C r e e k B a t h o l i t h Magma 12 B e h a v i o u r Of O x i d e s D u r i n g C r y s t a l l i z a t i o n 15 C o m p o s i t i o n Of C o - e x i s t i n g M e l t D u r i n g F r a c t i o n a l C r y s t a l l i z a t i o n Of The G u i c h o n C r e e k B a t h o l i t h 18 M o d i f i e d Thompson P r o j e c t i o n Diagram 20 Oxygen F u g a c i t y V a r i a t i o n D u r i n g C r y s t a l l i z a t i o n 23 C r y s t a l l i z a t i o n H i s t o r y Of The G u i c h o n C r e e k B a t h o l i t h 26 C o n c l u s i o n 39 R e f e r e n c e s 41 C h a p t e r T h r e e : D i s t r i b u t i o n Of Ba, Sr And Rb 46 A b s t r a c t 46 I n t r o d u c t i o n 48 P e t r o l o g y 51 Ba, Sr Ana Rb D i s t r i b u t i o n P a t t e r n s I n G u i c h o n C r e e k B a t h o l i t h 52 T r a c e Element C o n s t r a i n t s Of C r y s t a l l i z a t i o n M o d e ls Of The G u i c h o n B a t h o l i t h . 58 D i s c u s s i o n 66 C o n c l u s i o n 69 R e f e r e n c e s 71 C h a p t e r F o u r : V a r i a t i o n Of K/Rb R a t i o In Major U n i t s Of The G u i c h o n C r e e k B a t h o l i t h 75 A b s t r a c t 75 I n t r o d u c t i o n 76 K-Rb R e l a t i o n s In G u i c h o n C r e e k B a t h o l i t h Rocks 79 D i s c u s s i o n .79 C o n c l u s i o n 84 R e f e r e n c e s ' 86 C h a p t e r F i v e : D i s t r i b u t i o n Of C r , Co, N i , Cu Ana Zn 88 A b s t r a c t 88 I n t r o d u c t i o n 90 V a r i a t i o n Of T r a c e E l e m e n t s D u r i n g Magmatic C r y s t a l l i z a t i o n 98 D i s t r i b u t i o n C o e f f i c i e n t s A n a l y s i s Of V a r i a n c e Duncan's M u l t i p l e Range T e s t C o r r e l a t i o n M a t r i c e s C o n c l u s i o n R e f e r e n c e s C h a p t e r S i x : C o n c l u s i o n s And I m p l i c a t i o n s For E x p l o r a t i o n A p p e n d i x ( A - l ) : C a l c u l a t i o n s of b u l k d i s t r i b u t i o n C o e f f i c i e n t s of Ba, S r , and Rb A p p e n d i x ( A - 2 ) : C a l c u l a t i o n s t h e o r e t i c a l t r a c e e l e m e n t t r e n d s i n G u i c h o n Creek b a t h o l i t h i c r o c k s (Ba, Sr and Rb) A p p e n d i x ( B ) : M u l t i p l e r ange t e s t c a l c u l a t i o n A p p e m d i x ( C ) : Major and minor t r a c e element d a t a o f G u i c h o n Creek b a t h o l i t h i c r o c k s A p p e n d i x ( D ) : Sample L o c a t i o n Map v i i i L I S T OF TABLES T a b l e 2-1 : 2-2: 2 - 3 ( a ) 2 - 3 ( b ) 3-1 3-2 3- 3: 4- 1: 4- 2: 5- 1: 5 - 2 ( a ) : 5 - 2 ( b ) : 5-3: 5 - 4 ( a ) : 5 - 4 ( b ) : 5 - 4 ( c ) : 5 - 4 ( d ) : 5 - 4 ( e ) : 5 - 4 ( f ) : 5 - 5 ( a ) : 5 - 5 ( b ) : 5 - 5 ( c ) : 5 - 5 ( d ) : 5 - 5 ( e ) : T a b l e Of E x p o s e d A r e a s And Mean C h e m i c a l C o m p o s i t i o n s Of M a j o r P h a s e s Of The G u i c h o n C r e e k B a t h o l i t h A v e r a g e M i n e r a l Modes Of M a j o r Rock U n i t s Of G u i c h o n C r e e k B a t h o l i t h Magma C o m p o s i t i o n s A f t e r C o n s o l i d a t i o n Of V a r i o u s P h a s e s Of The G u i c h o n C r e e k B a t h o l i t h V a r i a t i o n Of N a 2 0 / ( N a 2 0 + K 2 O ) Ana C a 0 / A l 2 0 3 R a t i o s D u r i n g C r y s t a l l i z a t i o n Of G u i c h o n C r e e k B a t h o l i t h Magma M i n e r a l - M e l t D i s t r i b u t i o n C o e f f i c i e n t s B u l k D i s t r i b u t i o n C o e f f i c i e n t s C a l c u l a t e d From M o d a l M i n e r a l o g y Of Each P h a s e Of The G u i c h o n C r e e k B a t h o l i t h M o d a l M i n e r a l o g y Of G u i c h o n C r e e k B a t h o l i t h R o c k s Used R e s p o n s i b l e F o r Ba, S r , And Rb D i s t r i b u t i o n P a t t e r n s K-Rb R e l a t i o n s I n G u i c h o n C r e e k B a t h o l i t h R o c k s A d j u s t e d And A c t u a l M i n e r a l Modes Of G u i c h o n C r e e k B a t h o l i t h R o c k s Used I n C a l c u l a t i o n Of K/Rb R a t i o s C r y s t a l F i e l d S t a b i l i z a t i o n E n e r g i e s F o r T r a n s i t i o n M e t a l s A v e r a g e T r a c e E l e m e n t C o m p o s i t i o n Of G u i c h o n C r e e k B a t h o l i t h P h a s e s C a l c u l a t e d G u i c h o n C r e e k B a t h o l i t h R e s i d u a l M e l t C o m p o s i t i o n F o r E l e m e n t s Co, C r , Cu, N i , Pb And Zn B u l k D i s t r i b u t i o n C o e f f i c i e n t s o f Co, C r , Cu, N i , And Zn I n M a j o r Rock U n i t s Of G u i c h o n C r e e k B a t h o l i t h A n a l y s i s Of V a r i a n c e T a b l e R e s u l t s Of A n a l y s i s Of V a r i a n c e F o r Co R e s u l t s Of A n a l y s i s Of V a r i a n c e F o r Cr R e s u l t s Of A n a l y s i s Of V a r i a n c e F o r Cu R e s u l t s Of A n a l y s i s Of V a r i a n c e F o r N i R e s u l t s Of A n a l y s i s Of V a r i a n c e F o r Zn C o r r e l a t i o n M a t r i x T a b l e F o r T r a n s i t i o n E l e m e n t s I n B o r d e r Phase C o r r e l a t i o n M a t r i x T a b l e F o r T r a n s i t i o n E l e m e n t s I n G u i c h o n V a r i e t y C o r r e l a t i o n M a t r i x T a b l e F o r T r a n s i t i o n E l e m e n t s I n Chataway V a r i e t y C o r r e l a t i o n M a t r i x T a b l e F o r T r a n s i t i o n E l e m e n t s I n B e t h l e h e m P h a s e C o r r e l a t i o n M a t r i x T a b l e F o r T r a n s i t i o n E l e m e n t s I n B e t h s a i d a P h a s e 14 16 19 19 54 54 55 81 82 95 102 102 103 109 109 110 110 111 111 118 118 118 119 119 ix L I S T OF FIGURES F i g u r e 2 - 1 : Map o f B r i t i s h C o l u m b i a s h o w i n g l o c a t i o n o f G u i c h o n C r e e k b a t h o l i t h 8 2 - 2 : G e o l o g i c a l Map o f the G u i c h o n C r e e k b a t h o l i t h 11 2 - 3 : H a r k e r D i a g r a m 17 2 - 4 : M o d i f i e d Thompson P r o j e c t i o n d i a g r a m 22 2 - 5 : P l o t o f i r o n r a t i o v e r s u s sum o f A l k a l i s 25 2 - 6 : C o n c e p t u a l m o d e l o f magma body a t t h e t i m e o f i n t r u s t i o n ( T a d p o l e - s h a p e ) 31 2 - 7 ( a ) : C o n c e p t u a l m o d e l o f magma chamber a t t h e s t a r t o f c r y s t a l l i z a t i o n s h o w i n g f o r m a t i o n o f s a u c e r -l i k e shape o f t h e b a t h o l i t h 32 2 - 7 ( b ) : C o n c e p t u a l m o d e l o f magma chamber d u r i n g c r y s t a l l i z a t i o n o f B o r d e r and H i g h l a n d V a l l e y p h a s e s 33 2 - 7 ( c ) : C o n c e p t u a l m o d e l o f magma chamber a t o f c r y t a l l i z a t i a n where v o l a t i l e f l u i d s were r e l e a s e d 36 2- 7 ( d ) : M i g r a t i o n o f v o l a t i l e phase c e n t r e s o u t h w a r d s due to i n c r e a s e i n c r y s t a l l i z a t i o n a t t h e n o r t h e r n a t w h i c h f i r s t v o l a t i l e r e l e a s e o c c u r e d 37 3- 1: Rb v / s Ba p l o t s f o r ma jor r o c k u n i t s o f G u i c h o n C r e e k b a t h o l i t h 57 3 - 2 ( a ) : T h e o r e t i c a l d i s t r i b u t i o n t r e n d s o f Sr and Rb d u r i n g c r y s t a l l i z a t i o n o f G u i c h o n C r e e k b a t h o l i t h ( S r v / s Rb) 59 3 - 2 ( b ) : T h e o r e t i c a l d i s t r i b u t i o n t r e n d s o f Ba and Rb d u r i n g c r y s t a l l i z a t i o n o f G u i c h o n C r e e k b a t h o l i t h (Ba v / s Rb) 60 3 - 2 ( c ) : T h e o r e t i c a l d i s t r i b u t i o n t r e n d s o f Sr and Ba d u r i n g c r y s t a l l i z a t i o n o f G u i c h o n C r e e k b a t h o l i t h ( S r v / s Ba) 61 3 - 3 ( a ) : T r a c e e l e m e n t d a t a o f G u i c h o n C r e e k b a t h o l i t h s u p e r i m p o s e d on Sr v / s Rb d i a g r a m ( 3 - 2 ( a ) ) 63 3 - 3 ( b ) : T r a c e e l e m e n t d a t a o f G u i c h o n C r e e k b a t h o l i t h s u p e r i m p o s e d on Ba v / s Rb d i a g r a m o f ( 3 - 2 ( b ) ) 64 3- 3 ( c ) : T r a c e e l e m e n t d a t a o f G u i c h o n C r e e k b a t h o l i t h s u p e r i m p o s e d on Sr v / s Ba d i a g r a m o f ( 3 - 2 ( c ) ) 65 4 - 1: P l o t o f K/Rb R a t i o v / s K 78 4 - 2 : P l o t o f Rb v / s S i 0 2 i n G u i c h o n C r e e k b a t h o l i t h r o c k s 80 5 - 1: " 3 d " O r b i t a l e n e r g y l e v e l s f o r t r a n s i t i o n m e t a l s 92 5 - 2 : D i s t r i b u t i o n o f t r a n s i t i o n e l e m e n t s i n t h e m a j o r r o c k u n i t s o f S k a e r g a a r d I n t r u s i o n 96 5 - 3 : D u n c a n ' s M u l t i p l e Range t e s t d i a g r a m s 114 1 CHAPTER ONE  INTRODUCTION The c l o s e a s s o c i a t i o n o f a v a r i e t y o f m i n e r a l d e p o s i t s w i t h g r a n i t o i d p l u t o n s i s a r e c u r r i n g theme i n t h e e v o l u t i o n o f g e n e t i c m o d e l s o f t h e s e d e p o s i t s . Many t i n a n d t u n g s t e n d e p o s i t s h a v e b e e n r e c o g n i z e d a s c h a r a c t e r i s t i c a l l y a s s o c i a t e d w i t h g r a n i t o i d p l u t o n s . S i m i l a r l y , t h e c l o s e r e l a t i o n s h i p o f many Cu a n d / o r Mo p o r p h y r y t y p e d e p o s i t s w i t h p o r p h y r i t i c g r a n i t o i d i n t r u s i o n s i s s u f f i c i e n t l y i m p o r t a n t t o have i n f l u e n c e d t h e name o f t h i s d e p o s i t c l a s s . The l i s t n e e d n o t c o n t i n u e , t h e m i n e r a l p o t e n t i a l o f l a r g e g r a n i t o i d b o d i e s o r t e r r a n e s i s a n e s t a b l i s h e d f a c t . C o n t r o v e r s i e s h a v e r i s e n r e g a r d i n g d e b a t e s o f t h e g e n e t i c a s s o c i a t i o n b e t w e e n m i n e r a l d e p o s i t s and g r a n i t o i d t e r r a n e s . Two e x t r e m e p o i n t s o f v i e w a r e 1) t h a t p l u t o n s h a v e s i m p l y b e e n h e a t s o u r c e s t h a t p r o v i d e t h e e n e r g y f o r d r i v i n g g e o t h e r m a l c e l l s i n w h i c h t h e f l u i d a n d c o n t a i n e d m e t a l s a r e d e r i v e d f r o m o u t s i d e t h e p l u t o n and 2) t h e m a g m a t i c h y p o t h e s i s i n w h i c h mos t o r a l l o f t h e f l u i d a n d c o n t a i n e d m e t a l s w e r e an i n t e g r a l p a r t o f t h e magma t h a t c o n s o l i d a t e d t o p r o d u c e t h e p l u t o n i n q u e s t i o n . A s u b s t a n t i a l amount o f r e c e n t l i t e r a t u r e on t h e p o r p h y r y - t y p e d e p o s i t s w o u l d s u g g e s t t h a t d e p o s i t s i n t h i s 2 c l a s s have formed by c o n t r i b u t i o n from b o t h w i t h i n and w i t h o u t the s p a t i a l l y r e l a t e d p l u t o n , w i t h the p o s s i b i l i t y t h a t one or the o t h e r s o u r c e might p r e d o m i n a t e i n any p a r t i c u l a r c a s e . The p r e s e n t s t u d y i s c o n c e r n e d w i t h the development of an a p p l i e d l i t h o g e o c h e m i c a l a p p r o a c h to e x p l o r a t i o n of l a r g e g r a n i t o i d t e r r a n e s where o r e - f o r m i n g p r o c e s s e s have had a p r e d o m i n a n t l y magmatic f l a v o u r . For r e a s o n s o f g e o g r a p h i c a c c e s s i b i l i t y and r e a d y a v a i l a b i l i t y o f a s u b s t a n t i a l q u a n t i t y o f h i g h q u a l i t y s c i e n t i f i c d a t a , the G u i c h o n C r e e k b a t h o l i t h has been s e l e c t e d as a c a s e i n p o i n t to d e v e l o p a g e n e r a l and t h o r o u g h b a s i s f o r t h e use of l i t h o g e o c h e m i c a l d a t a f o r r e s o u r c e e v a l u a t i o n and m i n e r a l e x p l o r a t i o n i n s u c h t e r r a n e s . The s t u d y has t h r e e components: 1) Development o f a g e n e r a l c o n s o l i d a t i o n h i s t o r y o f t h e p l u t o n . 2) D e t a i l e d s t u d y o f t h e d i s t r i b u t i o n o f t r a c e e l e m e n t s d u r i n g c r y s t a l l i z a t i o n o f t h e p l u t o n and e v o l u t i o n of o r e f l u i d s ; and 3) C o n s i d e r a t i o n of l i t h o g e o c h e m i s t r y as a b a s i s f o r e x p l o r a t i o n , i n c l u d i n g r e l a t e d d a t a e v a l u a t i o n t e c h n i q u e s . Much o f t h e n e c e s s a r y i n f o r m a t i o n i s a l r e a d y a v a i l a b l e f r o m th e m u l t i t u d e o f s t u d i e s c o n d u c t e d on t h e b a t h o l i t h s i n c e t h e f i r s t g e o l o g i c a l map a p p e a r e d ( D u f f e l and M c T a g g a r t , 1952) t o t h e e x t e n s i v e r e c e n t works o f M c M i l l a n (1974; 1976; 1 9 81). These r e s u l t s have n e v e r been c o m p i l e d , e v a l u a t e d , and p r e s e n t e d i n a c o m p r e h e n s i v e manner r e l a t i n g d i r e c t l y to 3 r e g i o n a l and l o c a l e x p l o r a t i o n programmes. The purpose of t h i s work i s to use the d e t a i l e d knowledge now a v a i l a b l e f o r the Guichon Creek b a t h o l i t h as the ba s i s f o r a r e t r o s p e c t i v e study of the e v o l u t i o n of the b a t h o l i t h and r e l a t e d f l u i d phases as a basis f o r e x p l o r a t i o n of l a r g e g r a n i t o i d i n t r u s i o n s . 4 CHAPTER TWO  CRYSTALLIZATION MODEL ABSTRACT The g e n e r a l shape o f t h e G u i c h o n C r e e k b a t h o l i t h s u g g e s t s t h a t t h e magma was e m p l a c e d as a s i n g l e , l a r g e l y m o l t e n body i n p r e - e x i s t i n g s t r u c t u r e s . Due t o i t s l a r g e v o l u m e , a b o u t 3 x 1 0 3 km 3 o f m o l t e n r o c k , t h e c e n t r e o f t h e magma may have s u r g e d i n w a r d s u n d e r o u t l y i n g c o u n t r y r o c k s r e s u l t i n g i n t h e p r e s e n t s a u c e r - s h a p e o f t h e b a t h o l i t h , w i t h t h e n o r t h e r n end a t a r e l a t i v e l y h i g h e r e l e v a t i o n t h a n t h e s o u t h . C r y s t a l l i z a t i o n p r o c e e d e d a t b o t h ends t o f o r m a r e l a t i v e l y f i n e g r a i n e d c r y s t a l l i n e c o v e r ( B o r d e r p h a s e ) u n d e r w h i c h magma was s t i l l l a r g e l y m o l t e n . S u b s e q u e n t c r y s t a l l i z a t i o n was r e l a t i v e l y s l o w e r as e v i d e n c e d by i n c r e a s i n g g r a i n s i z e i n w a r d s t o w a r d s t h e c o r e o f t h e b a t h o l i t h . Due t o e l e v a t i o n d i f f e r e n c e s c r y s t a l l i z a t i o n was f a s t e r a t t h e n o r t h e r n end compared w i t h t h e s o u t h e r n end r e s u l t i n g i n e a r l i e r s a t u r a t i o n and e v o l u t i o n o f v o l a t i l e f l u i d s i n t h e n o r t h . A f t e r t h i s i n i t i a l s a t u r a t i o n and r e l e a s e o f v o l a t i l e f l u i d s c r y s t a l l i z a t i o n p r o c e e d e d w i t h m i g r a t i o n o f 5 v o l a t i l e c e n t r e s o u t h w a r d where a s e c o n d s a t u r a t i o n was a c h i e v e d . M o d i f i e d Thompson p r o j e c t i o n d i a g r a m f o r t h e s y s t e m K 2 0 - M g 0 - F e 0 - C a 0 - N a 2 O - A l 2 0 3 - S i 0 2 ~ H 2 0 p r e s e n t e d i n g r a p h i c a l f o r m as p l o t s o f A l - f a c t o r ( A l 2 0 3 - C a O - N a 2 0 - K 2 0 ) / ( F e O t + M g O ) a g a i n s t F e - f a c t o r F e O t / ( F e O t + MgO) s u g g e s t t h a t h o r n b l e n d e , b i o t i t e and p l a g i o c l a s e p l a y e d a c o n t r o l l i n g r o l e i n t h e d i f f e r e n t i a t i o n o f t h e b a t h o l i t h magma. INTRODUCTION C l o s e t e m p o r a l and s p a c i a l a s s o c i a t i o n o f p o r p h y r y t y p e m i n e r a l d e p o s i t s w i t h i n t r u s i v e and e x t r u s i v e c a l c - a l k a l i n e i g n e o u s r o c k s i s a w e l l e s t a b l i s h e d w o r l d - w i d e r e l a t i o n s h i p , ( e . g . T a u s o n e t a l , 1956) and s u c h d e p o s i t s a r e f o r t h e most p a r t c o n f i n e d t o t h e p r i n c i p a l o r o g e n i c b e l t s o f t h e w o r l d ( S i l l i t o e , 1 9 7 2 ) . I n t h e p r e s e n t w o rk, an a t t e m p t i s made t o c a r r y o u t a c l o s e r l o o k a t t h e r o c k - d e p o s i t a s s o c i a t i o n i n t h e G u i c h o n C r e e k B a t h o l i t h , w i t h s p e c i a l e m p h a s i s on t h o s e f e a t u r e s c o n s i d e r e d c r i t i c a l t o a g e n e t i c u n d e r s t a n d i n g o f a s s o c i a t e d p o r p h y r y - t y p e c o p p e r d e p o s i t s , and t h e b e a r i n g t h i s has on l i t h o g e o c h e m i c a l e x p l o r a t i o n . I n p a r t i c u l a r , we a r e c o n c e r n e d w i t h t h e g e n e t i c r e l a t i o n s h i p o f m i n e r a l d e p o s i t s i n t h e H i g h l a n d V a l l e y camp t o t h e s p a t i a l l y a s s o c i a t e d i n t r u s i v e r o c k s o f t h e G u i c h o n C r e e k B a t h o l i t h . P a r t I o f t h e s t u d y i s d e v o t e d t o magmatic p r o c e s s e s l e a d i n g t o emplacement and c o n s o l i d a t i o n o f b a t h o l i t h i c r o c k s . G e o l o g i c S e t t i n g The G u i c h o n C r e e k b a t h o l i t h i s one o f a s e r i e s o f p l u t o n s , r a n g i n g i n c o m p o s i t i o n f r o m c a l c - a l k a l i n e t o a l k a l i n e t h a t c r o p o u t i n a n o r t h e a s t e r l y t r e n d i n g b e l t , e x t e n d i n g f r o m 7 s o u t h e a s t e r n B r i t i s h C o l u m b i a t o s o u t h e r n Yukon T e r r i t o r y , ( F i g . 2 - 1 ) . I n s o u t h e r n B r i t i s h C o l u m b i a s e v e r a l o f t h e s e i n t r u s i o n s have been d a t e d a t a p p r o x i m a t e l y 200 m.a. , and t h e y a r e t h o u g h t t o be c o m a g m a t i c w i t h Upper T r i a s s i c V o l c a n i c r o c k s o f t h e N i c o l a F o r m a t i o n ( M c M i l l a n , 1976; P r e t o e t a l , 1 9 7 9 ) . The G u i c h o n C r e e k b a t h o l i t h i n t r u d e s b o t h t h e Upper P a l e o z o i c Cache C r e e k Group and t h e Upper T r i a s s i c N i c o l a Group ( M c T a g g a r t and D u f f e l , 1952; N o r t h c o t e , 1 9 6 9 ) . The p l u t o n o c c u p i e s an a r e a a p p r o x i m a t i n g a l i t t l e more t h a n one t h o u s a n d s q u a r e k i l o m e t r e s , c e n t r e d a b o u t 250 k i l o m e t r e s n o r t h e a s t o f V a n c o u v e r and 53.5 k i l o m e t r e s s o u t h w e s t o f K a m l o o p s . G e o l o g i c and r a d i o m e t r i c e v i d e n c e s u g g e s t t h a t t h e b a t h o l i t h was e m p l a c e d d u r i n g t h e Upper T r i a s i c ( M c T a g g a r t and D u f f e l , 1952; N o r t h c o t t e , 1 9 6 9 ) . P o t a s s i u m - a r g o n d a t i n g g i v e s model ages a v e r a g i n g 198 m.a. ( N o r t h c o t e , 1 9 6 9 ) , w h e r e a s a w h o l e r o c k Rb-Sr i s o c h r o n s u g g e s t s an age o f 205 m.a. ( P r e t o e t a l , 1 9 7 9 ) . M a p p a b l e p h a s e s o f t h e b a t h o l i t h young p r o g r e s s i v e l y i n w a r d s f r o m a m a f i c r i c h m a r g i n t o a f e l s i c c o r e . A b s o l u t e a g e s f o r i n d i v i d u a l p h a s e s c a n n o t be d i s t i n g u i s h e d ( N o r t h c o t e , 1 9 6 9 ) . Volume o f G u i c h o n B a t h o l i t h Magma C a l c u l a t i o n o f volume o f t h e G u i c h o n C r e e k B a t h o l i t h d epends on s u r f a c e a r e a m e a s u r e m e n t s and an i n t e r p r e t a t i o n o f t h e s u b s u r f a c e g e o m e t r y . S u r f a c e a r e a was c a l c u l a t e d by 8 / Figure 2-1: Map of B r i t i s h Columbia showing the d i s t r i b u t i o n of Upper T r i a s s i c v o l c a n i c and p l u t o n i c rocks (shaded area). Arrow p o i n t s to l o c a t i o n of Guichon Creek b a t h o l i t h ( M o d i f i e d from McMillan (1976)). 9 d i g i t i z i n g t h e most u p - t o - d a t e g e o l o g i c a l map o f t h e b a t h o l i t h ( M c M i l l a n , 1978) u s i n g c o m p u t e r b a s e d p r o c e d u r e s o f S i n c l a i r and B e n t z e n ( 1 9 8 3 ) . The shape o f t h e b a t h o l i t h was a p p r o x i m a t e d as an i n v e r t e d c o n i c a l body w i t h a f e e d e r 8 km. deep b e l o w t h e H i g h l a n d V a l l e y b a s e d on a r e g i o n a l g r a v i t y s u r v e y ( A g e r e t a l , 1 9 7 2 ) . Volume o f t h e b a t h o l i t h t h u s can be c a l c u l a t e d f r o m t h e volume o f a cone whose base has an a r e a e q u a l t o t h e a r e a o f e x p o s u r e o f t h e b a t h o l i t h and a h e i g h t o f 8 km. The vo l u m e c a l c u l a t e d i s 2675 km 3. N e g l e c t i n g t h e l o s s o f b a t h o l i t h i c m a t e r i a l by e r o s i o n a minimum volume o f magma ca n be a p p r o x i m a t e d by t h e p r e s e n t r o c k volume o f t h e b a t h o l i t h . STRUCTURE The s t r u c t u r e o f t h e G u i c h o n C r e e k b a t h o l i t h has been d i s c u s s e d by N o r t h c o t e ( 1 9 6 9 ) , Westerman ( 1 9 7 0 ) and M c M i l l a n ( 1 9 7 5 , 1976 and 19 7 8 ) . T h e b a t h o l i t h i s z o n e d c o m p o s i t i o n a l l y i n a r e g u l a r f a s h i o n , f r o m t h e m a r g i n i n w a r d s . I n t h i s r e g a r d , i t i s s i m i l a r t o many l a r g e i n t r u s i v e b o d i e s d e s c r i b e d i n t h e l i t e r a t u r e , s u c h as B i d w e l l B a r , C a l i f o r n i a ( C o mpton, 1 9 5 5 ) , West F a r r i n g t o n , N o r t h C a r o l i n a ( R a g l a n d and B u t l e r , 1 9 7 2 ) , L o c h Doon, S c o t l a n d ( T i n d l e e t a l , 1981) and o t h e r s . C o m p o s i t i o n a l z o n i n g i n some o f t h e s e p l u t o n s has been a t t r i b u t e d t o f r a c t i o n a l c r y s t a l l i z a t i o n o f a homogeneous magma ( V a n c e , 1961) and d i f f e r e n t i a t i o n o f v a r i o u s p u l s e s o f magma o f d i f f e r i n g c o m p o s i t i o n ( P i t c h e r and C o b b i n g , 1 9 7 2 ) . I n many 10 c a s e s w a l l r o c k c o n t a m i n a t i o n a p p e a r s t o have c o n t r i b u t e d t o some c o m p o s i t i o n a l v a r i a t i o n s i n a m a r g i n a l zone r e l a t i v e t o t h e r e m a i n d e r o f t h e p l u t o n . Z o n i n g i n t h e G u i c h o n C r e e k b a t h o l i t h , i l l u s t r a t e d i n f i g u r e 2-2, d e m o n s t r a t e s s y s t e m a t i c v a r i a t i o n f r o m m a r g i n t o c o r e , f o r s p e c i f i c g r a v i t y ( N o r t h c o t e , 1 9 6 9 ) , c o l o u r i n d e x , h o r n b l e n d e / b i o t i t e r a t i o , m a g n e t i c s u s c e p t i b i l i t y and t e x t u r e (W.J. M c M i l l a n , p e r s o n a l c o m m u n i c a t i o n , 1 9 8 3 ) . F o u r m a j o r p h a s e s o f t h e b a t h o l i t h a r e r e c o g n i z e d w h i c h f r o m t h e m a r g i n i n w a r d s a r e ( i ) B o r d e r p h a s e , l a r g e l y q u a r t z d i o r i t e t o q u a r t z m o n z o n i t e , ( i i ) H i g h l a n d V a l l e y phase c o n s i s t i n g o f G u i c h o n and Chataway v a r i e t i e s , o f q u a r t z d i o r i t e t o g r a n o d i o r i t e , ( i i i ) B e t h l e h e m phase g r a n o d i o r i t e w h i c h i n c l u d e s t h e more c o a r s e - g r a i n e d Skeena g r a n o d i o r i t e , and ( i v ) B e t h s a i d a p o r p h y r i t i c q u a r t z m o n z o n i t e . X e n o l i t h s o f c o u n t r y r o c k s a r e e s p e c i a l l y a b u n d a n t i n t h e B o r d e r p h a s e where a w i d e d i v e r s i t y o f t e x t u r e s has r e s u l t e d f r o m m e t a s o m a t i s m and r e - c r y s t a l l i z a t i o n o f w a l l r o c k i n c l u s i o n s . L o c a l l y , a s s i m i l a t i o n o f t h e m a f i c N i c o l a v o l c a n i c r o c k s ( b a s a l t i c t o a n d e s i t i c ) r e s u l t e d i n e v o l u t i o n o f m a f i c - r i c h v a r i e t i e s ( h o r n b l e n d i t e ) ; b u t on a l a r g e r s c a l e a s s i m i l a t i o n p l a y e d a m i n o r r o l e ( W e s t e r m a n , 1970; M c M i l l a n , 1 9 7 8 ) . T e x t u r a l e v i d e n c e , a b s e n c e o f c h i l l e d m a r g i n s and o t h e r g e o l o g i c e v i d e n c e s u g g e s t t h a t t h e magma may have been e m p l a c e d i n a m e s o z o n a l e n v i r o n m e n t ( N o r t h c o t e , 1 9 6 9 ) . P e t r o g r a p h i c a l l y t h e b a t h o l i t h c o n s i s t s o f v a r y i n g p r o p o r t i o n s o f p l a g i o c l a s e , p o t a s s i u m f e l d s p a r , b i o t i t e , 11 ASHCROFT o SPENCE'S BRIDGE Tunkwa Lake 3\ Mamit Lake LEGEND P O S T - B A T H O L I T H R O C K S H T E R T I A R Y H i V O L C A N I C A N D S E D I M E N T A R Y R O C K S C R E T A C E O U S (? ) V O L C A N I C A N D S E D I M E N T A R Y R O C K S J U R A S S I C S E D I M E N T A R Y R O C K S B A T H O L I T H R O C K S B E T H S A I D A P H A S E S K E E N A V A R I E T Y B E T H L E H E M P H A S E H I G H L A N D V A L L E Y P H A S E t r r t 7 1 C H A T A W A Y V A R I E T Y G U I C H O N V A R I E T Y B O R D E R P H A S E P R E - B A T H 0 U T H R O C K S H ? ] N I C O L A G R O U P VC LX HT BE SS CT Mineral Deposit Valley Cooper Lornex Highmont Bethlehem South Seas Cratgmont 16km S e a l * F igure.2-2:Geological .ap of the Guichon Creek b a t h o l i t h (modified a f t e r McMillan,1976). 12 h o r n b l e n d e , q u a r t z and a c c e s s o r y m i n e r a l s ( m a g n e t i t e , z i r c o n , s p hene and a p a t i t e ) . The p l a g i o c l a s e v a r i a t i o n i n b o t h An c o n t e n t and a b u n d a n c e i s v e r y r e s t r i c t e d r a n g i n g f r o m An47 t o An27f and v a r y i n g i n abundance by n o t more t h a n 5 volume p e r c e n t . M a f i c m i n e r a l s c o n s i s t m a i n l y o f h o r n b l e n d e and b i o t i t e . They r a n g e f r o m a b o u t 15 volume p e r c e n t i n t h e B o r d e r p h a s e t o 6 volume p e r c e n t i n B e t h s a i d a p h a s e . Q u a r t z and p o t a s s i u m f e l d s p a r a r e r e l a t i v e l y c o n s t a n t i n p r o p o r t i o n t h r o u g h o u t t h e b a t h o l i t h , q u a r t z a v e r a g i n g a b o u t 18 volume p e r c e n t w h e r e a s p o t a s s i u m f e l d s p a r i s as l o w as 3 volume p e r c e n t i n t h e B o r d e r p h a s e , and a b o u t 10 volume p e r c e n t i n t h e o t h e r p h a s e s . B e t h l e h e m and B e t h s a i d a p h a s e s , c o n s t i t u t e t h e i n n e r p a r t o f t h e b a t h o l i t h . S e v e r a l l i n e s o f e v i d e n c e i n d i c a t e t h a t t h e s e young p h a s e s c r y s t a l l i z e d u n d e r c o n d i t i o n s d i f f e r e n t f r o m t h o s e w h i c h p r e v a i l e d d u r i n g c r y s t a l l i z a t i o n o f o l d e r p h a s e s ( W e s t e r m a n , 1970; M c M i l l a n , 1 9 7 8 ) . I n p a r t i c u l a r , b o t h y o u n g e r p h a s e s a r e c h a r a c t e r i z e d by c o m p l e x l y z o n e d p l a g i o c l a s e c r y s t a l s , as o p p o s e d t o n o r m a l z o n i n g i n B o r d e r and H i g h l a n d V a l l e y p h a s e s , and a r e t h o u g h t t o have c r y s t a l l i z e d u n d e r h i g h e r w a t e r p r e s s u r e s ( W e s t e r m a n , 1970; O l a d e , 1 9 7 4 ) . COMPOSITION OF THE GUICHON BATHOLITH MAGMA D i f f e r e n t i a t i o n t r e n d s i n n a t u r a l s i l i c a t e s y s t e m s , be t h e y f r a c t i o n a l o r e q u i l i b r i u m c r y s t a l l i z a t i o n , c a n be e v a l u a t e d i f t h e c o m p o s i t i o n o f t h e o r i g i n a l p a r e n t magma i s 13 known. However, n a t u r e does n o t u s u a l l y a l l o w a c c e s s t o s u c h d i r e c t i n f o r m a t i o n , and as a r e s u l t v a r i o u s methods o f e s t i m a t i n g t h e c o m p o s i t i o n o f p a r e n t magmas have been d e v e l o p e d , i n c l u d i n g ( i ) g r a p h i c a l methods (Bowen, 1958) ( i i ) c o m p o s i t i o n a l and n u m e r i c a l methods ( B r y a n e t a l , 1962; B r y a n e t a l , 1968; W r i g h t e t a l , 1 9 7 0 ) . The l e a s t c o m p l i c a t e d and p e r h a p s t h e most a p p r o p r i a t e p r o c e d u r e i s t o a n a l y s e c h i l l e d m a r g i n s where t h e y e x i s t . T h i s method i s n o t p o s s i b l e i n t h e G u i c h o n C r e e k b a t h o l i t h b e c a u s e t h e o u t e r m o s t p h a s e g i v e s no e v i d e n c e o f c h i l l i n g . We a c c e p t t h e a r g u m e n t s o f N o r t h c o t e , ( 1 9 6 9 ) , W e s t e r m a n , ( 1 9 7 0 ) , and M c M i l l a n ( 1 9 7 6 , 1 9 7 8 ) , t h a t t h e b a t h o l i t h f o r m e d f r o m a s i n g l e magma i n j e c t i o n . F u r t h e r m o r e , we assume ( i ) t h a t p a r t i a l a s s i m i l a t i o n , r e p r e s e n t e d e s p e c i a l l y by l o c a l m a f i c v a r i e t i e s o f t h e B o r d e r p h a s e i s n e g l i g i b l e r e l a t i v e t o t h e enormous volume o f t h e b a t h o l i t h , and ( i i ) t h a t a r e a s o f d i f f e r e n t p h a s e s o f t h e b a t h o l i t h a p p r o x i m a t e p r o p o r t i o n s o f c r y s t a l l i n e m a t e r i a l t h a t f o r m e d f r o m a c l o s e d s y s t e m ( R a g l a n d and B u t l e r , 1 9 7 2 ) . S u r f a c e a r e a s f o r i n d i v i d u a l p h a s e s , c a l c u l a t e d as m e n t i o n e d p r e v i o u s l y , a r e l i s t e d i n T a b l e 2-1. Th e s e a r e a s o f e x p o s u r e o f b a t h o l i t h i c p h a s e s h a v e been u s e d as r e l a t i v e w e i g h t s i n t h e c a l c u l a t i o n s o f t h e c o m p o s i t i o n o f t h e b a t h o l i t h magma, as f o l l o w s : Y i = A i j X j where A i j = w e i g h t p e r c e n t o f o x i d e i i n p h a s e j : TABLE ( 2 - 1 ) TABLE OF EXPOSED AREAS AND MEAN CHEMICAL COMPOSITIONS OF MAJOR PHASES OF THE GUICHON CREEK BATHOLITH ROCK A r e a % Cum.% S i 0 2 A I 2 O 3 MgO CaO N a 2 0 K 2 O FeO Fe203 T i 0 2 MnO TYPE Km 2 A r e a A r e a B o r d e r P h a s e 335 33 33 58.87 16.66 3.16 6.14 3.79 1.60 3.85 2.38 0.81 0.11 G u i c h o n V a r i e t y 270 27 60 61.78 16.59 2.75 5.30 4.00 2.08 2.65 2.33 0.62 0.09 Chataway V a r i e t y 160 16 76 64.15 16.26 2.00 4.74 4.26 2.11 2.01 1.97 0.50 0.07 B e t h l e h e m Phase 118 12 88 65.15 15.76 1.58 4.02 4.34 2.23 1.77 1.74 0.46 0.07 B e t h s a i d a P h a s e 170 12 100 73.70 14.38 0.34 1.72 4.25 3.41 0.56 0.74 0.14 0.05 Av. B a t h -o l i t h 1000 100 100 63.37 16.14 2.28 4.81 4.04 2.15 2.54 1.96 0.57 0.09 i = 1 t o n and j = 1 t o k X j = s u r f a c e a r e a o f phase j ( i n p e r c e n t a r e a ) . Y i = w e i g h t p e r c e n t o f o x i d e i i n magma. The r e s u l t i n g w e i g h t e d a v e r a g e c o m p o s i t i o n o f t h e b a t h o l i t h magma i s a l s o l i s t e d i n T a b l e 2-1. BEHAVIOUR OF OXIDES DURING CRYSTALLIZATION M a j o r o x i d e v a r i a t i o n s ( F i g u r e 2-3) c l e a r l y depend on d i f f e r e n t i a t i o n h i s t o r y . I n p a r t i c u l a r , we w i l l r e l a t e o x i d e v a r i a t i o n t o m i n e r a l modes. M i n e r a l s i n t h e G u i c h o n C r e e k b a t h o l i t h t h a t may be r e l a t e d t o d e c r e a s e i n CaO w i t h i n c r e a s i n g d i f f e r e n t i a t i o n a r e p l a g i o c l a s e and h o r n b l e n d e ( T a b l e 2 - 2 ) ; o t h e r p o s s i b l e CaO c o n c e n t r a t o r s s u c h as a u g i t e and a p a t i t e o c c u r as m i n o r c o m p o n e n t s . The b e h a v i o u r o f CaO a c c o m p a n i e d by a c o m p a r a b l e d e c r e a s e i n A I 2 O 3 i n d i c a t e t h a t p l a g i o c l a s e and h o r n b l e n d e a r e t h e mai n m i n e r a l s c o n t r o l l i n g d i f f e r e n t i a t i o n a t l e a s t d u r i n g c o n s o l i d a t i o n o f t h e B o r d e r p h a s e and t h e G u i c h o n v a r i e t y . The c u r v e o f K 2 0 becomes c o n s t a n t b e t w e e n 62 and 64 w e i g h t p e r c e n t S i 0 2 , g i v i n g u n i f o r m K 2 O c o n t e n t s i n t h e Chataway v a r i e t y and B e t h l e h e m and B e t h s a i d a p h a s e s . T a b l e 2-2 shows t h a t b i o t i t e i s d o m i n a n t r e l a t i v e t o h o r n b l e n d e f o l l o w i n g t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n v a r i e t y . The g r a d u a l i n c r e a s e i n N a 2 0 ( F i g . 2-3) may be a s s o c i a t e d w i t h c r y s t a l l i z a t i o n o f t h e a s s e m b l a g e a m p h i b o l e - p l a g i o c l a s e - q u a r t z w h i c h i s p r o m i n e n t i n N a 2 0 - r i c h magmas ( C a w t h o r n , 1 9 7 6 ) . A p p e a r a n c e o f t h e f o r g o i n g a s s e m b l a g e TABLE 2-2 AVERAGE MODES IN VOLUME PERCENT OF GUICHON CREEK BATHOLITH MAJOR ROCK UNITS (DATA FROM NORTHCOTE, 1969) M i n e r a l s B o r d e r P. G u i c h o n V P l a g i o c l a s e 54 .72 49 .91 O r t h o c l a s e 3. 18 10 .04 Q u a r t z 17 .85 17 .65 B i o t i t e 7. 32 9. 16 H o r n b l e n d e 10 .35 8. 14 A u g i t e 3. 89 2. 46 Opague 2. 51 2. 20 Sphene 0. 09 0. 38 A p a t i t e 0. 06 0. 02 Z i r c o n 0. 03 0. 04 100.00 100.00 Chataway B e t h l e h e m P. B e t h s a i d a P. 54.34 49.02 52.11 10.93 9.95 10.56 20.64 20.81 29.39 5.19 3.16 6.27 6.76 4.33 0.40 1.84 2.31 0.97 0.22 0.30 0.15 0.08 0.10 0.13 — 0.02 0.02 100.00 90.00 100.00 20 -10 -2 -1 -3 -2 -1 -3 -2 -0 6 -5 -4 -3 -2 -4 -3 -2 -1 A l 2 0 3 i 1 1 1 r F e 2 0 3 T 1 1 r \ X ~i ' r FeO -i 1 1 r 1 " r MgO -i r -i 1 1 1 1 p CaO -i 1 1 1 1 1 1-Na 2 0 -> r K 2 0 5 7 6 1 6 5 6 9 SiQ 2 (Wt. %) — i — 7 3 Figure.2-3: V a r i a t i o n diagram (Harker diagram) of oxides versus s i l i c a (see t e x t f o r d i s c u s s i o n ) . a c c o m p a n i e d by b i o t i t e d u r i n g p r o g r e s s i v e c r y s t a l l i z a t i o n p u s h e s t h e magma c o m p o s i t i o n t o w a r d s t r o n d h j e m i t i c ( B a r t h , 1 9 6 2 ) . The r e l a t i v e l y l o w s l o p e o f t h e K 2 0 v a r i a t i o n g r a p h ( F i g . 2-3) s u g g e s t s t h a t K 2 0 was n o t a c c u m u l a t i n g i n t h e s i l i c a t e m e l t as d i f f e r e n t i a t i o n p r o c e e d e d , as i n d i c a t e d by t h e low p o t a s h f e l d s p a r c o n t e n t o f young p h a s e s . R a g l a n d and B u t l e r , ( 1 9 7 2 ) s u g g e s t t h a t c r y s t a l l i z a t i o n o f a m p h i b o l e and b i o t i t e c o u l d be r e l a t e d t o c h a n g e s i n CaO, S i 0 2 and Na/(Na+K) r a t i o o f t h e s i l i c a t e magma, w i t h a m p h i b o l e c e a s i n g t o c r y s t a l l i z e i n s i l i c a t e m e l t s o f l e s s t h a n 2 w e i g h t p e r c e n t CaO, more t h a n 70 p e r c e n t S i 0 2 , and Na/(Na+K) r a t i o o f l e s s t h a n 0.6. COMPOSITION OF CO-EXISTING MELT DURING  FRACTIONAL CRYSTALLIZATION S i l i c a t e m e l t s c o e x i s t i n g w i t h e a c h phase o f t h e G u i c h o n Creek B a t h o l i t h were c a l c u l a t e d u s i n g t h e r e l a t i o n d e v e l o p e d by R a g l a n d and B u t l e r , ( 1 9 7 2 ) . Y = MZ - NX m - n where Y = o x i d e c o m p o s i t i o n o f l i q u i d ( i . e . p r o p o r t i o n o f e a c h o x i d e phase a f t e r r e m o v a l o f amount e q u a l t o X ) . X = o x i d e c o m p o s i t i o n o f s o l i d . Z = c o m p o s i t i o n o f o x i d e i n o r i g i n a l l i q u i d . m = amount o f m e l t b e f o r e r e m o v a l o f n. n = amount o f m e l t c r y s t a l l i z e d as X. TABLE ( 2 - 3 a ) MAGMA COMPOSITIONS AFTER CONSOLIDATION OF VARIOUS PHASES OF THE GUICHON CREEK BATHOLITH O x i d e s L P LB L G LC L B e S i 0 2 63.37 65.59 68.18 70.83 73.67 A 1 2 0 3 16.14 15.88 15.40 14.83 14.37 MgO 2.28 1.85 1.24 0.73 0.31 CaO 4.81 4.15 3.37 2.46 1.68 N a 2 0 4.04 4.16 4.27 4.28 4.25 K 2 0 2.15 2.42 2.65 3.01 3.40 FeO 2.54 1.89 1.38 0.96 0.56 F e 2 0 3 1.96 1.75 1.43 1.07 0.74 T i 0 2 0.57 0.45 0.34 0. 23 0.12 MnO 0.09 0.08 0.07 0.07 0.07 Lp = p a r e n t magma c o m p o s i t i o n ; Lgo = magma c o m p o s i t i o n a f t e r r e m o v a l o f s o l i d c o m p o s i t i o n e q u i v a l e n t t o B o r d e r p h a s e : LQTJ = magma a f t e r r e m o v a l o f G u i c h o n v a r i e t y : L Q ^ = magma a f t e r r e m o v a l o f Chataway v a r i e t y : and Lgj? - magma c o m p o s i t i o n a f t e r r e m o v a l o f B e t h l e h e m p h a s e . TABLE ( 2 - 3 b ) VARIATION OF N a 2 0 / ( N a 2 + K 2 0 ) AND C a O / A l 2 0 3 RATIOS DURING CRYSTALLIZATION OF GUICHON CREEK BATHOLITH MAGMA COMPOSITION OF S I L I C A T E MELT N a 2 0 / ( N a 2 0 + K 2 0 ) C a 0 / A l 2 0 3 PARENT MAGMA COMPOSITION ( L p ) 0.65 0.298 MAGMA AFTER REMOVAL OF BORDER P H A S E ( L B 0 ) 0.63 0.261 MAGMA AFTER REMOVAL OF GUICHON V. (LQTJ) 0.62 0.219 MAGMA AFTER REMOVAL OF CHATAWAY V. ( L Q H ) ° - 5 9 0.169 MAGMA AFTER REMOVAL OF BETHLEHEM P . ( L B E ) 0.44 0.117 T h i s r e l a t i o n s h i p i s u s e f u l i n t h e c a s e o f p e r f e c t f r a c t i o n a l c r y s t a l l i z a t i o n s i n c e i t r e q u i r e s i m m e d i a t e r e m o v a l o f m i n e r a l s f r o m t h e r e m a i n i n g magma. Such a c o n d i t i o n i s o n l y c r u d e l y met by a c o n s o l i d a t i n g p l u t o n . C a l c u l a t e d i d e a l l i q u i d c o m p o s i t i o n s c o r r e s p o n d i n g t o v a r i o u s p h a s e s o f t h e G u i c h o n C r e e k b a t h o l i t h a r e l i s t e d i n T a b l e 2 - 3 ( a ) . T a b l e 2 - 3 ( b ) c o n t a i n s t h e v a r i a t i o n s i n C a / A l and Na/(Na+K) r a t i o s i n s i l i c a t e m e l t s as d i f f e r e n t i a t i o n p r o c e e d e d . I n T a b l e 2 - 3 ( b ) we see t h a t b o t h CaO and Na/(Na+K) r a t i o w i l l f a l l b e l o w 2 p e r c e n t and 0.6 r e p e c t i v e l y a f t e r c r y s t a l l i z a t i o n o f B e t h l e h e m p h a s e w h i c h i s c o n s i s t e n t w i t h t h e do m i n a n c e o f b i o t i t e o v e r h o r n b l e n d e i n t h e B e t h s a i d a p h a s e . MODIFIED THOMPSON PROJECTION DIAGRAM C h e m i c a l d i f f e r e n t i a t i o n t r e n d s i n c r y s t a l l i z i n g magmas ca n be shown on t h e m o d i f i e d Thompson p r o j e c t i o n d i a g r a m ( N e s b i t t and C r a m e r , 1 9 8 1 ) . Thompson, ( 1 9 5 7 ) d e v e l o p e d a g r a p h i c a l method on w h i c h e q u i l i b r i u m m a t e r i a l b a l a n c e s i n p e l i t i c r o c k s , r e p r e s e n t e d by t h e s y s t e m K 2 0 - MgO - FeO -A I 2 O 3 - S i 0 2 - H 20 c a n be e v a l u a t e d . I n p e l i t i c r o c k s t h e c h e m i c a l p o t e n t i a l s o f b o t h S i 0 2 and H 20 were c o n s i d e r e d b u f f e r e d by q u a r t z and c h e m i c a l r e a c t i o n s o r e x t e r n a l r e s e r v o i r s r e s p e c t i v e l y . Hence t h e m i n e r a l a s s e m b l a g e e q u i l i b r a t e d w i t h q u a r t z c a n be p r o j e c t e d f r o m t h e K 2 0 - A l 2 0 3 - MgO - FeO d i a g r a m . To r e p r e s e n t i g n e o u s r o c k s on t h e Thompson d i a g r a m , t h e 21 above s y s t e m c a n be m o d i f i e d by t h e a d d i t i o n o f NaG*2 and CaO. H owever, a d d i t i o n o f N a 2 0 i n c r e a s e s d e g r e e s o f f r e e d o m by one, w h e r e a s p r e s e n c e o f a l b i t e p l a g i o c l a s e w i l l r e d u c e d e g r e e s o f f r e e d o m by one ( N e s b i t t e t a l , 1 9 8 1 ) . The b u l k o f CaO i n i g n e o u s r o c k s c a n be assumed t o be c o n t a i n e d i n p l a g i o c l a s e e ven t h o u g h some m i n o r m i n e r a l s s u c h as a p a t i t e a r e C a - b e a r i n g . The c h e m i c a l p o t e n t i a l o f CaO i n i g n e o u s r o c k s c a n be c o n s i d e r e d b u f f e r e d by C a - b e a r i n g m i n e r a l s . Hence t h e Thompson p r o j e c t i o n d i a g r a m ca n be u s e d t o show n o n - f e l s i c m i n e r a l p r o p o r t i o n s e q u i l i b r a t e d w i t h q u a r t z - a l b i t e - a n o r t h i t e and H 2 0 . The d i a g r a m t h e r e f o r e i s drawn w i t h t h e A l - f a c t o r as t h e o r d i n a t e and t h e F e - f a c t o r as t h e a b s c i s s a . The A l - f a c t o r i s t h e amount o f a l u m i n a a s s o c i a t e d w i t h Fe and Mg i n f e r r o m a g n e s i a n m i n e r a l s a s s u m i n g t h a t N a / A l and K / A l r a t i o s i n f e l d s p a r s a r e c o n s t a n t . T h e F e - f a c t o r i s t h e amount o f t o t a l Fe a s s o c i a t e d w i t h Mg a f t e r r e m o v a l o f Fe i n b o t h m a g n e t i t e s and i l m e n i t e s . H e nce, t h e Fe F a c t o r i s g i v e n by t h e r e l a t i o n F e O f V C FeOt + MgO) w h e r e a s t h e A l - f a c t o r i s g i v e n by ( A l 2 0 3 -CaO - N a 2 0 - K 2 0 ) / ( F e O t + MgO). F i g u r e 2-4 i s t h e r e f o r e t h e m o d i f i e d Thompson p r o j e c t i o n d i a g r a m f o r r o c k s o f t h e G u i c h o n C r e e k b a t h o l i t h . S i n c e t h e m i n e r a l o g i c a l c o m p o s i t i o n s o f t h e G u i c h o n C r e e k b a t h o l i t h r o c k s a r e n o t a v a i l a b l e , t h e m i n e r a l c o m p o s i t i o n f i e l d s i n F i g u r e 2-4 a r e b a s e d on i d e a l m i n e r a l c o m p o s i t i o n s g i v e n i n N e s b i t t and C r a m e r , ( 1 9 8 1 ) . The s o l i d c u r v e i n F i g u r e 2-4 i s t h e b u l k r o c k c h e m i c a l c o m p o s i t i o n t r e n d o f r o c k s o f t h e G u i c h o n C r e e k b a t h o l i t h . I t 22 0.5 -o S, 0.0 - 0 . 5 t BE \ Q r - Y~~ •A I v V , Bi 1 — \ \ fBO / 4 1 1 1 Hbde 0.8 Figure 2-4; 0.7 0.6 0.5 0 .4 0.3 Fe Factor Modified Thompson projection, Al factor versus Fe factor showing differentiation trend of whole rock composition of the Guichon Creek batholith (solid line (G)) with respect to magic mineral fields biotite (Bi) and hornblende (Hbde). BO = Border phase; GU = Guichon variety; CH = Chataway variety; BL = Bethlehem phase and BE = Bethsaida phase. The broken line shows a similar trend for the Tuolumne Pluton series of California derived from data by Bateman and Chappell (1979). 23 p r e d i c t s t h a t t h e e a r l y d i f f e r e n t i a t e s h ave a b o u t e q u a l p r o p o r t i o n s o f h o r n b l e n d e and b i o t i t e , w i t h b i o t i t e i m p o r t a n c e i n c r e a s i n g r a p i d l y w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n . The d i a g r a m s u g g e s t s t h a t b i o t i t e p l a y e d a f a r more i m p o r t a n t r o l e t h a n s u g g e s t e d by e x i s t i n g c r y s t a l l i z a t i o n m o d e l s o f t h e G u i c h o n C r e e k b a t h o l i t h . F i g u r e 2-4 t h e r e f o r e s u g g e s t s t h a t c r y s t a l l i z a t i o n was c o n t r o l l e d by f r a c t i o n a t i o n o f h o r n b l e n d e -b i o t i t e - p l a g i o c l a s e a s s e m b l a g e w i t h h o r n b l e n d e i m p o r t a n c e d e c r e a s i n g more r a p i d l y w i t h i n c r e a s i n g d i f f e r e n t i a t i o n . T h u s , i t i s n o t e n t i r e l y c o r r e c t t o s u g g e s t t h a t c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h was c o n t r o l l e d by h o r n b l e n d e and p l a g i o c l a s e i n e a r l y d i f f e r e n t i a t e s and l a t e r by b i o t i t e and p l a g i o c l a s e ( O l a d e , 1974; M c M i l l a n , 1 9 7 8 ) . The above i n t e r p r e t a t i o n i s c o n s i s t e n t w i t h o b s e r v e d modal m i n e r a l v a r i a t i o n s d i s c u s s e d a b o v e . The d o t t e d c u r v e i n F i g u r e 2-4 shows t h e b u l k c h e m i c a l c o m p o s i t i o n o f t h e Tuolumne P l u t o n S e r i e s r o c k s i n S o u t h e r n C a l i f o r n i a (Bateman e t a l , 1 9 7 9 ) . Thus f r o m t h e b u l k r o c k c h e m i s t r y , t h e Tuolumne S e r i e s r o c k s a r e more m a f i c t h a n G u i c h o n r o c k s , t h e y a r e c h a r a c t e r i z e d by h i g h h o r n b l e n d e p r o p o r t i o n s i n e a r l y d i f f e r e n t i a t e s . OXYGEN FUGACITY VARIATION DURING CRYSTALLIZATION I n g e n e r a l t h e o x y g e n f u g a c i t y v a r i e s s y s t e m a t i c a l l y d u r i n g t h e c r y s t a l l i z a t i o n o f s i l i c a t e m e l t s . B a s a l t i c m e l t s c r y s t a l l i z e u n d e r d e c r e a s i n g o x y g e n f u g a c i t y , w h e r e a s c a l c - a l k a l i n e m e l t s c r y s t a l l i z e u n d e r i n c r e a s i n g o x y g e n c o n d i t i o n s . The v a r i a t i o n o f o x y g e n f u g a c i t y p l a y s an i m p o r t a n t r o l e i n t h e d i f f e r e n t i a t i o n o f s i l i c a t e magmas by c o n t r o l l i n g s t a b l e m i n e r a l a s s e m b l a g e s . Wones and E u g s t e r , ( 1 9 6 5 ) , showed t h a t t h e Mg/Mg + Fe r a t i o i n b i o t i t e s may be a p r o d u c t o f h i g h t e m p e r a t u r e s a t c o n s t a n t o x y g e n f u g a c t i y , a n d / o r v a r y i n g o x y g e n f u g a c i t y w i t h d e c r e a s i n g t e m p e r a t u r e . I n c r e a s i n g o x y g e n f u g a c i t y f a v o u r s M g - r i c h b i o t i t e s , s i n c e F e 2 + w i l l be o x i d i z e d t o F e 3 + w h i c h may l e a d t o c r y s t a l l i z a t i o n o f o x i d e m i n e r a l s s u c h as m a g n e t i t e . The F e - r i c h b i o t i t e s a t h i g h o x y g e n p r e s s u r e s b r e a k down t o p o t a s h f e l d s p a r and m a g n e t i t e . K F e 3 A l S i 3 0 ! o ( O H ) 2 -^=± K A l S i 3 0 8 + Fe304 + H 2 b i o t i t e k - f e l d s p a r m a g n e t i t e T h e r e f o r e v a r i a t i o n o f Mg/(Mg + Fe) r a t i o may g i v e an i n d i c a t o r o f o x y g e n c o n d i t i o n s d u r i n g c r y s t a l l i z a t i o n o f b i o t i t e s . A s i m i l a r r e l a t i o n s h i p was o b s e r v e d i n h o r n b l e n d e s ( C a w t h o r n , 1 9 7 6 ) . W esterman, ( 1 9 7 0 ) m e a s u r e d Fe and Mg c o n t e n t s i n b i o t i t e s o f G u i c h o n C r e e k B a t h o l i t h r o c k s , and showed t h a t Mg/(Mg + F e ) i n b i o t i t e s i n c r e a s e s w i t h d i f f e r e n t i a t i o n t o w a r d s t h e y o u n g e r p h a s e s . F i g u r e 2-5 i s a p l o t o f t h e i r o n r a t i o ( F e 3 + / F e 3 + + F e 2 + + M n 2 + ) a g a i n s t t h e sum o f a l k a l i o x i d e s . The i r o n r a t i o i s a f u n c t i o n o f s i l i c a t e m e l t s t r u c t u r e . I n s i l i c a t e m e l t s , t h e s t r u c t u r e can be an e s t i m a t e o f m e l t v i s c o s i t i e s . S i l i c a t e m e l t v i s c o s i t i e s i n c r e a s e w i t h i n c r e a s i n g n e t w o r k f o r m i n g m e t a l s s u c h as Na+, K+, C a 2 + and o t h e r s , w i t h c o n s t a n t A l and S i 0 2 - M e t a l s s u c h as N a + and K + f o r m s i l i c a t e s t r u c t u r e s s u c h as NaA102 w h i c h i n c r e a s e w i t h i n c r e a s i n g v i s c o s i t y ( B o t t i n g a e t a l , 1 9 7 2 ) , 25 5 6 7 8 ( N a 2 0 + K 2 0 ) Wt. % o I 3*^ " 2 1 Figure 2-5: Iron r a t i o (Fe /(Fe +Fe +Mn )) as mole proportion versus t o t a l a l k a l i s (Na20+K20) as weight percent. Positive correlation suggests increase i n oxidation s with progressive c r y s t a l l i z a t i o n . where A l o c c u p i e s t e t r a h e d r a l s i t e s . E x c e s s A l o v e r n e t w o r k m o d i f i e r s e n t e r s o c t a h e d r a l s i t e s and does n o t a f f e c t t h e v i s c o s i t y . I n c r e a s i n g e x p e r i m e n t a l e v i d e n c e ( D i c k e n s o n and H e s s , 1980) s u g g e s t s t h a t F e 3 + p l a y s t h e same r o l e as A l 3 + e s p e c i a l l y i n p r e s e n c e o f Na, f o r m i n g s t r u c t u r e s s u c h a s NaFe02, where F e 3 + i s i n t e t r a h e d r a l c o o r d i n a t i o n . S i n c e a l k a l i m e t a l s i n c r e a s e w i t h i n c r e a s i n g d i f f e r e n t i a t i o n , F e 3 + s h o u l d c o r r e l a t e w i t h t h e sum o f a l k a l i m e t a l s i n o x i d i z i n g e n v i r o n m e n t . F i g u r e 2-5 a l s o s u g g e s t s t h a t F e 3 + w h i c h i s a f u n c t i o n o f o x i d a t i o n p o t e n t i a l c o r r e l a t e s w i t h t h e sum o f a l k a l i i n d i c a t i n g i n c r e a s i n g o x y g e n f u g a c i t y w i t h d i f f e r e n t i a t i o n . CRYSTALLIZATION HISTORY OF THE GUICHON CREEK BATHOLITH The e v o l u t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h f r o m a s i n g l e magma has been r e f e r r e d t o p r e v i o u s l y and has been d i s c u s s e d i n d e t a i l by N o r t h c o t e , ( 1 9 6 9 ) . W e s t e r m a n , ( 1 9 7 0 ) a l s o t o o k a s i m i l a r v i e w t h o u g h d i f f e r i n g w i t h N o r t h c o t e by i n v o k i n g magma c o n v e c t i o n t o e x p l a i n some f e a t u r e s o f t h e b a t h o l i t h , s u c h as l i m i t e d a l i g n m e n t o f p l a g i o c l a s e and h o r n b l e n d e c r y s t a l s o f t h e B o r d e r p h a s e . Westerman a l s o d i s m i s s e d t h e s u g g e s t i o n by N o r t h c o t e t h a t G u i c h o n C r e e k b a t h o l i t h magma c r y s t a l l i z e d u n d e r d i f f e r e n t e n v i r o n m e n t s ; m e s o z o n a l f o r o l d e r p h a s e s ( B o r d e r and H i g h l a n d V a l l e y ) , and e p i z o n a l f o r y o u n g e r p h a s e s , w i t h d e p t h o f emplacement c o n t r o l l e d by s u r f a c e e r o s i o n as e v i d e n c e d by 27 a b s e n c e o f Lower J u r a s s i c r o c k s . H i s a r g u m e n t s were b a s e d on t h e g r o u n d s t h a t t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h was a c o n t i n u o u s phenomenon w h i c h t o o k a r e l a t i v e l y s h o r t t i m e compared t o t h a t may o t h e r w i s e be r e q u i r e d f o r t h e r e m o v a l o f huge masses o f o v e r l y i n g r o c k s by e r o s i o n . H o wever, n e i t h e r o f t h e s e a u t h o r s a d d r e s s e d t h e T h e o l o g i c a l p r o b l e m s t h a t w o u l d r e s u l t f r o m e m placement o f s u c h a l a r g e v o l u m e o f low d e n s i t y m a t e r i a l i n an a r e a i n e x c e s s o f 1000 km 2, b e n e a t h a t h i n m a n t l e o f s o l i d r o c k . F o r c o n v e c t i o n t o o c c u r on s u c h a l a r g e s c a l e , t h e magma w o u l d have t o be l a r g e l y l i q u i d , o t h e r w i s e o n l y l o c a l i z e d v o r t i c e s w o u l d r e s u l t . F o r s u c h l a r g e s c a l e l o w d e n s i t y m a t e r i a l t o have been e m p l a c e d l a r g e l y l i q u i d , l a r g e s c a l e s u b s i d e n c e ( c a u l d r o n c o l l a p s e ) , n o t e v i d e n t i n t h e H i g h l a n d V a l l e y w o u l d be e x p e c t e d . The a l i g n m e n t o f c r y s t a l s r e f e r r e d t o and t h e i r c o n f i n e m e n t t o t h e o u t e r B o r d e r p h a s e may a l s o have r e s u l t e d f r o m f l o w b a n d i n g due t o m i g r a t i o n o f c r y s t a l s downward f r o m t h e c o o l e r p a r t s o f t h e magma where t h e y f o r m e d , d u r i n g t h e a s c e n t o f c u r r e n t s i n t h e magma chamber and may have v e r y l i t t l e t o do w i t h c o n v e c t i o n . On t h e o t h e r h a n d , c a u s e s o f magma s u r g e s a d v o c a t e d by N o r t h c o t e , n e e d t o be e x p l o r e d a d e q u a t e l y . We need t o a d d r e s s o u r s e l v e s t o d i f f e r e n c e s t h a t e x i s t b e t w e e n v a r i e t i e s o f t h e H i g h l a n d V a l l e y p h a s e ; f o r i n s t a n c e , t h e d o m i n a n c e o f G u i c h o n v a r i e t y i n v t h e n o r t h e r n p a r t s o f t h e b a t h o l i t h r e l a t i v e t o Chataway v a r i e t y , and t h e p r e v a l e n c e o f b i o t i t e i n t h e G u i c h o n v a r i e t y as o p p o s e d t o h o r n b l e n d e i n t h e Chataway ( M c M i l l a n , 28 1 9 7 6 ) . There a r e s e v e r a l i m p o r t a n t q u e s t i o n s t o be a n s w e r e d c o n c e r n i n g t he c r y s t a l l i z a t i o n and s o l i d i f i c a t i o n o f t he G u i c h o n Creek b a t h o l i t h , one o f w h i c h i s t h e i n f l u e n c e o f e p i s o d i c v o l a t i l e r e l e a s e on t h e emplacement o f magma p u l s e s . S i n c e t h e two v a r i e t i e s o f t h e H i g h l a n d V a l l e y p h a s e a r e somewhat d i f f e r e n t m i n e r a l o g i c a l l y i t w o u l d a l s o be i n s t r u c t i v e t o a s s e s s t h e i n f l u e n c e o f v o l a t i l e p r e s s u r e on t h e i r r e s p e c t i v e c r y s t a l l i z a t i o n . The c r y s t a l l i z a t i o n m odel s u i t a b l e f o r t h e G u i c h o n C r e e k b a t h o l i t h s h o u l d be a b l e t o an s w e r t h e above q u e s t i o n s , as w e l l as a d d r e s s i n g t h e f o l l o w i n g p o i n t s : ( 1 ) a s y m m e t r i c a l n a t u r e o f t h e b a t h o l i t h . ( 2 ) h e t e r o g e n e o u s n a t u r e o f t h e G u i c h o n v a r i e t y as compared t o t h e more homogeneous Chataway v a r i e t y . ( 3 ) i m p o r t a n c e o f v a r i a t i o n s o f m a f i c m i n e r a l s ( h o r n b l e n d e and b i o t i t e ) i n t h e two v a r i e t i e s o f t h e H i g h l a n d V a l l e y phase ( G u i c h o n and C h a t a w a y ) . ( 4 ) t h e s t a t e o f magma a t t h e t i m e o f i n t r u s i o n . ( 5 ) t i m i n g o f v o l a t i l e r e l e a s e . The shape o f i n t r u s i o n s a r e a d i r e c t r e f l e c t i o n o f t h e v i s c o s i t y c o n t r a s t t h a t e x i s t e d b e t ween i n t r u d i n g magma and h o s t r o c k s ( P i t c h e r , 1 9 7 9 ) . I n g e n e r a l , a l a r g e l y m o l t e n magma w o u l d h a v e a r e l a t i v e l y l a r g e v i s c o s i t y c o n t r a s t t o t h e o v e r l y i n g r o c k s , w h e r e a s i n a c r y s t a l l i z i n g magma t h i s c o n t r a s t i s r e d u c e d ( R a m b e r g , 1 9 7 0 ) . L a r g e v i s c o s i t y c o n t r a s t s a r e l i k e l y t o l e a d t o l a r g e s c a l e s u b s i d e n c e ( C a u l d r o n c o l l a p s e ) . w h e r e a s s m a l l v i s c o s i t y c o n t r a s t r e s u l t s i n doming. The 29 v i s c o s i t y c o n t r a s t a l s o r e f l e c t s t h e r a t e o f , magma a s c e n t . Low v i s c o s i t y magma i s ame n a b l e t o f a i r l y r a p i d a s c e n t , i n w h i c h t h e r a t e o f h e a t l o s s ( h e n c e c r y s t a l l i z a t i o n ) w o u l d be l o w , and as a r e s u l t s u c h a magma w i l l b r e a k t h r o u g h t h e s u r f a c e as a p h e n o c r y s t - f r e e s u p e r h e a t e d body. Slow a s c e n t , on t h e o t h e r h a n d , w i l l l e a d t o g r e a t e r l o s s o f h e a t f r o m t h e magma t h r o u g h c o n d u c t i o n , h e n c e c r y s t a l l i z a t i o n w i l l be a c c e l e r a t e d g r e a t l y r e s u l t i n g i n c o m p l e t e c r y s t a l l i z a t i o n a t g r e a t d e p t h s ( M a r s h , e t a l , 1 9 7 8 ) . C r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h seems t o have began s h o r t l y b e f o r e e m p l a c e m e n t . X e n o c r y s t s o f c l i n o p y r o x e n e , o r t h o p y r o x e n e , p l a g i o c l a s e , and h o r n b l e n d e a r e c o n s i d e r e d t o be l i q u i d u s m i n e r a l s ( M c M i l l a n , 1 9 7 8 ) . The a l i g n m e n t o f t h e s e c r y s t a l s i n t h e B o r d e r phase c l e a r l y s u g g e s t s t h a t t h e y f o r m e d p a r t o f a c r y s t a l l i n e mush a t t h e t i m e o f i n t r u s i o n . A p p e a r a n c e o f c l i n o p y r o x e n e , o r t h o p y r o x e n e and p l a g i o c l a s e as l i q u i d u s m i n e r a l s s u g g e s t s t h a t t h e magma c o n t a i n e d a b o u t 2 w e i g h t p e r c e n t w a t e r ( E g g l e r , 1972; G r e e n , 1 9 7 2 ) . P r e s e n c e o f h o r n b l e n d e a l s o s u p p o r t s t h i s v i e w . A c r y s t a l l i z i n g a n d e s i t i c magma w i t h t e m p e r a t u r e s a r o u n d 950°C, e m p l a c e d a t a m e s o z o n a l e n v i r o n m e n t (5 t o 9 km), w o u l d have v e r y l i t t l e v i s c o s i t y c o n t r a s t w i t h a n d e s i t i c and b a s a l t i c N i c o l a v o l c a n i c r o c k s , w h i c h w o u l d be f a i r l y d u c t i l e a t t h o s e d e p t h s . I n s u c h a s i t u a t i o n t h e magma w o u l d have a s c e n d e d , a t l e a s t i n p a r t by p u s h i n g a s i d e d u c t i l e r o c k s and p r o d u c i n g o v e r l y i n g d o m e - l i k e s t r u c t u r e s . S i n c e t h e h o s t r o c k s 30 w o u l d be f a i r l y d u c t i l e t h e y w o u l d be e a s i l y s h o u l d e r e d a s i d e by t h e magma, as i t r i s e s , and t h e n f a l l i n g i n p l a c e a f t e r t h e b u l k o f t h e magma has p a s s e d , c l o s i n g i n t o f o r m t a d p o l e - l i k e s t r u c t u r e s ( P i t c h e r , 1 9 7 9 ) , ( s e e a l s o F i g . 2 - 6 ) . However, i n t h e c a s e o f t h e G u i c h o n C r e e k b a t h o l i t h , t h i s i d e a l s i t u a t i o n was n o t a t t a i n e d . The shape o f t h e b a t h o l i t h i s i n t e r p r e t e d f r o m r e s u l t s o f a g r a v i t y s u r v e y ( A g e r e t a l , 1972) as a s a u c e r - s h a p e d , f u n n e l - l i k e body w i t h a f e e d e r b e l o w t h e H i g h l a n d V a l l e y p h a s e , t i l t e d t o t h e n o r t h e a s t . The h e t e r o g e n i t y o f t h e G u i c h o n v a r i e t y o f t h e H i g h l a n d V a l l e y p h a s e , t o g e t h e r w i t h t h e a s y m m e t r i c a l g e o m e t r y o f t h e b a t h o l i t h s u g g e s t t h a t t h e magma was e m p l a c e d i n a p r e - e x i s t i n g a s y m m e t r i c s t r u c t u r e ( F i g . 2 - 7 ( a ) ) . B e c a u s e o f t h e l a r g e s c a l e a r e a l e x t e n t i n t o w h i c h t h i s f a i r l y l ow d e n s i t y m a t e r i a l (magma) was e m p l a c e d , t h e c e n t r a l p a r t o f t h e magma must have s u r g e d downward t o p r o d u c e : ( a ) a b a s i n - l i k e s t r u c t u r e , and ( b ) two d o m e - l i k e s t r u c t u r e s s e p a r a t e d by a v a l l e y , w i t h t h e h i g h e r 'dome' t o t h e n o r t h . Due t o t h e s l o w a s c e n t and low v i s c o s i t y c o n t r a s t b e t ween magma and r o c k s , c r y s t a l l i z a t i o n p r o c e e d e d f a i r l y f a s t f o r m i n g a c r y s t a l l i n e c o v e r ( B o r d e r p h a s e ) , b e l o w w h i c h magma was s t i l l l a r g e l y m o l t e n . T h i s manner o f c r y s t a l l i z a t i o n r e s u l t e d i n f o r m a t i o n o f a c l o s e d s y s t e m . W i t h t h e c r y s t a l l i n e r i n d ( cover) i n p l a c e , c r y s t a l l i z a t i o n p r o c e e d e d f a i r l y f a s t a t t h e n o r t h e r n end due t o e l e v a t i o n d i f f e r e n c e s , l e a d i n g t o t h e more h e t e r o g e n e o u s G u i c h o n v a r i e t y w h e r e a s a 31 NW S E Figure 2-6: Tadpole=like shape of the magma chamber i s thought to res u l t from i n t r u s i o n of magma body in t o d u c t i l e rocks (D). Low v i s c o s i t y contrast i s assumed between d u c t i l e country rock and magma. 32 NW Figure.2-7(a) The saucer-like shape of the Guichon Creek batholith may have been caused by subsidence of overlying rocks indicated by arrow ( L P - Load pressure). Some bouyancy of roof material prevented complete roof collapse. The subsidence created a central depression of the upper contact flanked by two dome-like structures labelled I and II. Horizontal scale is about 5 times vertical scale. NW •33. SE Figure 2-7(b) : Further c r y s t a l l i z a t i o n after the formation of the c r y s t a l l i n e cover or Border phase (BO), led to consolidation ° r f \ H i § h l a n d V a l l e y P^se, consiting of Guichon variety CGU) i n the north and Chataway variety (CH) i n the south V o l a t i l e saturation of the magma occurred at the end of this stage. Horizontal scale i s about 5 times v e r t i c a l scale. 34 s l o w e r c r y s t a l l i z a t i o n i n t h e s o u t h r e s u l t e d i n t h e more u n i f o r m Chataway g r a n o d i o r i t e . I f t h e G u i c h o n b a t h o l i t h magma c o n t a i n e d a b o u t 2 w e i g h t p e r c e n t w a t e r , as i n d i c a t e d a b o v e , t h e n i t i s i n s t r u c t i v e t o e v a l u a t e t h e c o n d i t i o n s u n d e r w h i c h s a t u r a t i o n o f t h e magma d u r i n g c r y s t a l l i z a t i o n was a c h i e v e d . Magmas o f c o m p a r a b l e c o m p o s i t i o n c o n t a i n i n g s i m i l a r amounts o f w a t e r , have been f o u n d t o become s a t u r a t e d a f t e r a b o u t 33 p e r c e n t c r y s t a l l i z a t i o n a t 0.5 Kb, l o a d p r e s s u r e ( i . e . 2 km d e p t h ) ; a f t e r 72 p e r c e n t c r y s t a l l i z a t i o n a t 2 Kb (8 km d e p t h ) and a f t e r 83 p e r c e n t c r y s t a l l i z a t i o n u n d e r 5 Kb (18 km d e p t h ) (Burnham and Ohmoto, 1 9 8 0 ) . We c a n e s t i m a t e p e r c e n t c r y s t a l l i z a t i o n by p e r c e n t c u m u l a t i v e a r e a o f e x p o s e d b a t h o l i t h r o c k s . W i t h t h i s a p p r o a c h we f i n d t h a t B o r d e r phase r e p r e s e n t s 33 p e r c e n t c r y s t a l l i z a t i o n and H i g h l a n d V a l l e y 72 p e r c e n t . An assumed magma d e p t h o f 5 t o 9 km ( N o r t h c o t t e , 1 9 6 9 ) , w o u l d l e a d t o magma s a t u r a t i o n w i t h v o l a t i l e s d u r i n g c r y s t a l l i z a t i o n o f t h e H i g h l a n d V a l l e y p h a s e . C r y s t a l l i z a t i o n beyond s a t u r a t i o n l e a d s t o s e p a r a t i o n o f a v o l t i l e p h a s e . A s s u m i n g t h a t c o m p l e x z o n i n g o f p l a g i o c l a s e i s r e l a t e d t o p e r i o d i c r e l e a s e o f v o l a t i l e s ( V a n c e , 1 9 6 2 ) , t h e s e c a l c u l a t i o n s a r e t h e r f o r e i n a c c o r d a n c e w i t h t h e s u g g e s t i o n by M c M i l l a n , ( 1 9 7 8 ) and West e r m a n , ( 1 9 7 0 ) , t h a t t h e n a t u r e o f p l a g i o c l a s e z o n i n g i n t h e G u i c h o n C r e e k b a t h o l i t h d i v i d e s t h e b a t h o l i t h i n t o two p a r t s : ( i ) B o r d e r and H i g h l a n d V a l l e y p h a s e s c h a r a c t e r i z e d by n o r m a l l y z o n e d p l a g i o c l a s e and ( i i ) B e t h l e h e m and B e t h s a i d a p h a s e s t y p i f i e d by c o m p l e x l y 35 z o n e d p l a g i o c l a s e . The n e c e s s a r y i m p l i c a t i o n o f o f c o m p l e x l y z o n e d p l a g i o c l a s e i s t h a t p e r i o d i c r e l e a s e o f an i m m i s c i b l e v o l a t i l e p h a s e p r o d u c e d i n t e r m i t t a n t p r e s s u r e c h a n g e s . B e c a u s e o f a d i f f e r e n c e i n e l e v a t i o n o f t h e two h i g h s o f t h e u p p e r s u r f a c e o f t h e magma, v o l a t i l e p hase w o u l d have c o l l e c t e d more r a p i d l y i n zone I o f F i g u r e 2 - 7 ( b ) . E v i d e n c e o f t h i s i s t h e d o m i n a n c e o f b i o t i t e i n t h e G u i c h o n v a r i e t y , t h u s s u g g e s t i n g t h a t h i g h e r v o l a t i l e p r e s s u r e s e x i s t e d d u r i n g t h e c r y s t a l l i z a t i o n o f G u i c h o n v a r i e t y r e l a t i v e t o Chataway v a r i e t y . R a p i d e r o s i o n o f o v e r l y i n g c o u n t r y r o c k i s p r o b a b l e where doming i s an i n t e g r a l p a r t o f t h e c r y s t a l l i z a t i o n h i s t o r y o f a l a r g e p l u t o n . T h e r e f o r e , t h e c o m b i n a t i o n o f e r o s i o n and c r y s t a l l i z a t i o n , s o o n l e d t o e x c e s s o f v o l a t i l e p r e s s u r e o v e r c o n f i n i n g p r e s s u r e . The e x p e c t e d r e s u l t i s an e x p l o s i o n i n d u c e d f r a c t u r i n g o f w a l l r o c k s ( F i g . . 2 - 7 ( c ) ) , p r o d u c i n g a c o m p l e x n e t w o r k o f f r a c t u r e s and e x p l o s i o n b r e c c i a . Such an e x p l o s i v e p r o c e s s had two main e f f e c t s : ( i ) f r a c t u r i n g o f w a l l r o c k s , and ( i i ) m i g r a t i o n o f m o l t e n magma downward t o d e e p e r e n v i r o n m e n t s ( F i g . 2 - 7 ( d ) ) . I n t h e c a s e o f t h e G u i c h o n C r e e k b a t h o l i t h , downward m i g r a t i o n o f magma was t e m p o r a r y as t h e e s c a p e o f v o l a t i l e s c r e a t e d l o w e r p r e s s u r e s w h i c h r e s u l t e d i n u p s u r g e o f magma p u l s e s f o r m i n g d y k e s and c r o s s c u t t i n g p h a s e s o f i n t r u s i o n . The u p s u r g e o f p a r t l y c r y s t a l l i z e d magma i n t o p a r t l y c r y s t a l l i n e magma mush o f t h e magma c a r a p i c e c o u l d r e s u l t i n e i t h e r one o r b o t h o f t h e f o l l o w i n g : NW Figure 2-7(c) Further c r y s t a l l i z a t i o n a f t e r Highland Valley phase (GU and CH) produced Bethlehem phase (BE) accompanied by rapid release of a v o l a t i l e phase. This evolution of a v o l a t i l e phase resulted into excesses of confining pressure over l i t h o s t a t i c pressure leading to explosive f r a c t u r i n g of overlying rocks and escape of f l u i d s from the magma chamber. The explostion caused sudden down-ward migration of the magma body (Short Arrows V.P.). ES = erosion surface. Horizontal scale about 5 times v e r t i c a l scale. 37 NW SE ES R$S.... Figure.2-7(d) 1 J ^ . / * + + + + +""-NfcV iV \ \ /o+ + + + + + vV XV + + + + + + vj ask V X o/(5 + + + + + n+tt SsSSSSSA 5 / w + + + + + + +ni NSSSSSSSJWC. + + + + + + SSSSSsSSSSSfcftW l m + + + + + + +ft ^ ^ ^ ^ ^ ^ ^ s s j t w ^ V + MAGMA +*+M 5^^^^^^^^§ss^ss^ssX + + + + + + ^^^^^^^^^^^^^^^^^V + + + + + S ^ ^ ^ ^ ^ ^ ^ ^ ^ S ^ ^ c ^ S ^ ^ t 1 + + + + + ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ k + + + + + Release of volatile fluids created a low pressure region at I, resulting in an upsurge of magma currents (arrows) into the partly crystalline magma carapice. • This resulted in a comparatively higher crystallization rate at the northern end than southern end of the batholith, and migration of both crystallization front and volatile centre southward to II contemporaneous with crystallization of Bethsaida phase. Horizontal scale is about 5 times vertical scale. 38 ( i ) g r a d a t i o n a l c o n t a c t s , w h i c h w o u l d be due t o t h e m i x i n g o f two p a r t l y c r y s t a l l i n e magma b o d i e s u n d e r s l o w r a t e o f s o l i d i f i c a t i o n l e a d i n g t o h i g h e r d i f f u s i o n o f m a t e r i a l s h ence h o m o g e n i s i n g t h e c o m p o s i t i o n s o f t h e two magma b o d i e s . ( i i ) s h a r p i n t r u s i v e c o n t a c t s , due t o h i g h e r r a t e o f s o l i d i f i c a t i o n t h u s l i m i t i n g e x t e n s i v e magma m i x i n g t h r o u g h d i f f u s i o n . The r e l e a s e o f t h e v o l a t i l e c o n s t i t u e n t s i n t h e n o r t h e r n end l e d t o r a p i d c r y s t a l l i z a t i o n and r e s u l t e d i n t h e m i g r a t i o n o f t h e v o l a t i l e c e n t r e t o zone I I of F i g u r e 2 - 7 ( b ) . C o n t i n u i n g c r y s t a l l i z a t i o n l e d t o s a t u r a t i o n o f t h e magma w i t h v o l a t i l e p h ase whose r e l e a s e l e d t o t h e s e c o n d f r a c t u r i n g i n a d i f f e r e n t e n v i r o n m e n t . T h i s manner o f c r y s t a l l i z a t i o n c a n be r e l a t e d t o c o m p l e x f r a c t u r e p a t t e r n s o b s e r v e d i n t h e G u i c h o n C r e e k b a t h o l i t h . The f a n a r r a y o f j o i n t s t o g e t h e r w i t h c o n t a i n e d p o r p h y r y d y k e s a r o u n d B e t h l e h e m S a l i e n t , T r o j a n and J a c k s o n B a s i n s , n o r t h o f t h e mai n v a l l e y were c o n s i d e r e d c o g n a t e ( W h i t e e t a l , 1 9 5 7 ) , and a r e m a r k e d l y d i f f e r e n t f r o m t h o s e i n t h e s o u t h o f t h e main v a l l e y , w h i c h i s c o n s i s t e n t w i t h r e l e a s e o f v o l a t i l e i n s t a g e s ( H y l a n d s , 1 9 7 2 ) . F r a c t u r e s s o u t h o f t h e main v a l l e y a r e c e n t r e d a r o u n d B e t h s a i d a p r o p e r t y and show a c o n s p i c u o u s l a c k o f t h e n o r t h t r e n d i n g j o i n t s p r o m i n e n t n o r t h o f t h e v a l l e y ( W h i t e e t a l , 1 9 5 7 ) . T h e n a t u r e o f t h e j o i n t p a t t e r n t o g e t h e r w i t h a s s o c i a t e d a c i d i c d y k e s s u p p o r t t h e mode o f emplacement a d v a n c e d a b o v e . 3 9 CONCLUSION T h i s work r e p r e s e n t s an a t t e m p t t o r e v i e w and s u p p l e m e n t where p o s s i b l e an u n d e r s t a n d i n g o f c r y s t a l l i z a t i o n p r o c e s s e s i n t h e G u i c h o n C r e e k b a t h o l i t h . The r e l a t i o n o f t h e b u l k r o c k c h e m i s t r y o f t h e b a t h o l i t h i c p h a s e s t o m i n e r a l p r o p o r t i o n s ( F i g . 2-4) s u g g e s t t h a t d i f f e r e n t i a t i o n o f t h e G u i c h o n magma was c o n t r o l l e d by t h e c r y s t a l l i z a t i o n o f b i o t i t e - h o r n b l e n d e and p l a g i o c l a s e n o t j u s t by h o r n b l e n d e and p l a g i o c l a s e i n e a r l y d i f f e r e n t i a t e s and b i o t i t e and p l a g i o c l a s e i n y o u n g e r r o c k s as s u g g e s t e d by e a r l i e r m o d e l s ( O l a d e , 1974; M c M i l l a n , 1 9 7 8 ) . The p r e d i c t i o n s d e r i v e d f r o m F i g u r e 2-4 a r e v e r y much c o n s i s t e n t w i t h t h e modal m i n e r a l o g y o f t h e b a t h o l i t h i c r o c k s . M i n e r a l m o d a l a b u n d a n c e s ( T a b l e 2-2) s u m m a r i z e d f r o m N o r t h c o t e , ( 1 9 6 9 ) show t h a t b i o t i t e i s i m p o r t a n t i n a l l p h a s e s and r e l a t i v e l y u n i f o r m a t a b o u t 10 volume p e r c e n t t h r o u g h o u t t h e b a t h o l i t h , w h e r e a s h o r n b l e n d e d e c r e a s e s r a p i d l y w i t h i n c r e a s i n g d i f f e r e n t i a t i o n . The s u g g e s t e d d i f f e r e n t i a t i o n t r e n d w o u l d h a v e v e r y p r o f o u n d e f f e c t s on v a r i a t i o n o f b o t h m a j o r and t r a c e e l e m e n t s d u r i n g p r o g r e s s i v e c r y s t a l l i z a t i o n . C r y s t a l l i z a t i o n o f b o t h b i o t i t e and h o r n b l e n d e w h i c h a r e t h e main c o n c e n t r a t o r s o f p o t a s s i u m , w o u l d v e r y much i n f l u e n c e t h e p o t a s s i u m d i s t r i b u t i o n d u r i n g c r y s t a l l i z a t i o n . The e a r l y a p p p e a r a n c e o f t h o s e m i n e r a l s r e s u l t e d i n r e l a t i v e d e p l e t i o n o f p o t a s s i u m i n r e s i d u a l m e l t s 40 as e v i d e n c e d by t h e l o w p r o p o r t i o n o f p o t a s s i u m f e l d s p a r i n r o c k s o f t h e G u i c h d n C r e e k b a t h o l i t h . S i n c e b i o t i t e t h e main b u f f e r o f t h e K 2 0 c h e m i c a l p o t e n t i a l was r e l a t i v e l y c o n s t a n t t h r o u g h o u t t h e c r y s t a l l i z a t i o n o f t h e magma, o v e r a l l p o t a s s i u m f e l d s p a r c o n t e n t i s r e l a t i v e l y c o n s t a n t a t a b o u t 10 volume p e r c e n t . O t h e r e v i d e n c e d i s c u s s e d above and by o t h e r a u t h o r s ( N o r t h c o t e , 1969: M c M i l l a n , 1976: Westerman, 1970: H y l a n d s , 1 9 7 2 ) , i n d i c a t e s t h a t t h e G u i c h o n C r e e k b a t h o l i t h f o r m e d f r o m a s i n g l e magma p e r h a p s t h r o u g h i n s i t u f r a c t i o n a t i o n . T h u s t h i s s u g g e s t s t h a t c r y s t a l f r a c t i o n a t i o n p l a y e d an i m p o r t a n t r o l e i n c o m p o s i t i o n a l z o n i n g o f t h e body. 41 REFERENCES A g e r , C.A., M c M i l l a n , W.J. and U l r y c h , T . J . , ( 1 9 7 3 ) : G r a v i t y M a g n e t i c s , and G e o l o g y o f t h e G u i c h o n C r e e k B a t h o l i t h . B.C. M i n i s t r y o f M i n e s and P e t . R e s . , B u l l . 62. A n f i l o g o v , V.N., G r a g i n a , G . I . , B o b y l e v , I . 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J . , 1 9 8 1: G r a p h i c a l R e p r e s e n t -a t i o n o f M i n e r a l E q u i l i b r i a and M a t e r i a l s B a l a n c e s i n I g n e o u s R o c k s . C o n t r i b . M i n e r a l . P e t r o l . , V. 78, p. 136-144. Northcote, K.E., 1969: G e o l o g y and G e o c h r o n o l o g y o f t h e G u i c h o n C r e e k B a t h o l i t h . B.C. M i n i s t r y o f M i n . & P e t r . R e s . B u l l . 56. O l a d e , M.A.D., 1974: B e d r o c k G e o c h e m i s t r y o f P o r p h y r y C opper D e p o s i t s , H i g h l a n d V a l l e y , B.C. Ph.D. t h s i s U n i v e r s i t y o f B r i t i s h C o l u m b i a ( U n p u b l i s h e d ) P a r s o n s , I . , 1978: F e l d s p a r s and F l u i d s i n C o o l i n g P l u t o n s . M i n e r a l . Mag. L o n d . , V o l . 42, p. 1-18. P i t c h e r , W.S., 1979: The N a t u r e , A s c e n t and Emplacement o f G r a n i t i c Magmas. J . G e o l . S o c . L o n d . , V. 136, p. 627-6 6 2 . P r e t o , V.A., 1977: The N i c o l a G r o u p : M e s o z o i c V o l c a n i s m R e l a t e d t o R i f t i n g i n S o u t h e r n B.C. G e o l . A s s o c . Can. S p e c . P a p . No. 16, p. 39-57. P r e t o , V.A., O s a t e n k o , M.J., M c M i l l a n , W.J., A r m s t r o n g , R.L., 1979: I s o t o p i c d a t e s and S t r o n t i u m I s o t o p i c r a t i o s f o r P l u t o n i c and V o l c a n i c r o c k s , i n t h e Q u e s n e l T r o u g h and N i c o l a B e l t , S. C e n t r a l . B.C. Can. J . E a r t h . S c i . , V. 16, p. 1658-1672. R a g l a n d , P.C., and B u t l e r , J.R., 1972: C r y s t a l l i z a t i o n o f t h e West F a r r i n g t o n P l u t o n , N o r t h C a r o l i n a , U.S.A. J o u r . P e t r o l . , V. 13, p. 381-404. Ramberg, H., 1970: M o d e l S t u d i e s i n r e l a t i o n t o I n t r u s i o n o f p l u t o n i c b o d i e s . I n "Mechanisms o f I g n e o u s _ I n t r u s i o n , " ( N e w a l l & R a s t , e d . ) . G e o l . J o u r . S p e c . I s s u e , No. 2, p. 261-286. S i l l i t o e , R.H., 1972: A p l a t e T e c t o n i c M o d e l f o r t h e O r i g i n o f P o r p h y r y C opper D e p o s i t s . E c o n . G e o l . , V. 67, p. 184-197. T a u s o n , L.V., and K i a v c h e n k o , L.A., 1956: C h a r a c t e r i s t i c s o f L e a d and Z i n d i s t r i b u t i o n i n m i n e r a l s o f t h e C a l e d o n i a n g r a n i t o i d s o f t h e Susamyr b a t h o l i t h i n c e n t r a l L i o n s h a n . 45 G e o c h e m i s t r y , 1., p. 7 8 - 88. T a y l o r , H.P. J r . , 1974: The a p p l i c a t i o n o f o x y g e n and h y d r o g e n i s o l t o p e s s t u d i e s t o p r o b l e m s o f h y d r o t h e r m a l a l t e r a t i o n and o r e d e p o s i t i o n . E c o n . G e o l . , V. 69, p. 8 4 3 - 8 8 3 . T a y l o r , R. P., and F r y e r , B . J . , 1983: S t r o n t i u m I s o t o p e G e o c h e m i s t r y o f t h e S a n t a R i t a P o r p h y r y C o p p e r D e p o s i t , New M e x i c o . E c o n . G e o l . , V. 78, p. 170-174. T i n d l e , A.G., and P e a r c e , J.A., 1981: P e t r o g e n e t i c M o d e l l i n g of i n s i t u F r a c t i o n a l C r y s t a l l i z a t i o n i n t h e Zoned L o c k Doon P l u t o n , S c o t l a n d . C o n t r i b . M i n e r a l . P e t r o l . , V. 78, P. 196-207, V a n c e , J.A., 1961: Zoned G r a n i t i c I n t r u s i o n s ; An A l t e r n a t i v e H y p o t h e s i s o f O r i g i n . G e o l . S o c . Am. B u l l . , V. 72, p. 1723-1728. V a n c e , J.A., 1962: Z o n i n g i n I g n e o u s P l a g i o c l a s e : N o r m a l and O s c i l l a t o r y Z o n i n g . Amer. J . S c i . , V. 260, p. 7 4 6 -760. V i l l a s , R.N. and N o r t o n , D., 1977: I r r e v e r s i b l e Mass T r a n s f e r b e t w e e n C i r c u l a t i n g H y d r o t h e r m a l F l u i d s and M a y f l o w e r S t o c k . E c o n . G e o l . , V o l . 72, p. 1 471-1504. W e s t e r m a n , C . J . , 1970: A P e t r o g e n i c S t u d y o f t h e G u i c h o n C r e e k B a t h o l i t h , B.C. MSc. t h e s i s U n i v e r s i t y o f B r i t i s h C o l u m b i a ( U n p u b l i s h e d ) . W h i t e , W.H., Thompson, R.M., and M c T a g g a r t , K.C., 1957: The G e o l o g y and M i n e r a l D e p o s i t s o f t h e H i g h l a n d V a l l e y , B.C. CIMM., V. 60, p. 2 7 3 -289. Wones, D.R., and E u g s t e r , H.P., 1965: S t a b i l i t y o f b i o t i t e , E x p e r i m e n t , T h e o r y and A p p l i c a t i o n . Am. M i n e r a l . , V. 50, p. 1228-1272. W r i g h t , T.L. and D o h e r t y , P.C., 1970: A l i n e a r p r o g r a m m i n g and l e a s t - s q u a r e method f o r s o l v i n g P e t r o l o g i c m i x i n g P r o b l e m s . G e o l . S o c . Am,. B u l l . , V. 8 1 , p. 1995-2008. 46 CHAPTER THREE  DISTRIBUTION OF B a , S r AND Rb.  ABSTRACT V a r i a t i o n o f B a , S r , and Rb d u r i n g c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h a r e m o d e l l e d f o r b o t h R a y l e i g h f r a c t i o n a t i o n and s u r f a c e e q u i l i b r i u m m o d e l s u s i n g c o n s t a n t m i n e r a l p r o p o r t i o n s ( 5 0 p e r c e n t p l a g i o c l a s e , 1 8 p e r c e n t q u a r t z , 1 0 p e r c e n t p o t a s s i u m f e l d s p a r , 8 p e r c e n t h o r n b l e n d e and 9 p e r c e n t b i o t i t e ) . T h e b u l k d i s t r i b u t i o n c o e f f i c i e n t s c a l c u l a t e d f r o m t h e p r e c e d i n g m i n e r a l p r o p o r t i o n s a r e Dj3 a = 1 . 3 7 , D g r = 1 . 8 4 and D R D = 0 . 3 8 5 where m i n e r a l - m e l t p a r t i t i o n c o e f f i c i e n t s were c o n s i d e r e d c o n s t a n t t h r o u g h o u t t h e c r y s t a l l i z a t i o n o f t h e b a t h o l i t h magma. The c a l c u l a t e d D v a l u e s a r e more t h a n one f o r Ba and Sr and l e s s t h a n one f o r Rb s u g g e s t i n g t h a t S r and Ba were p a r t i t i o n e d p r e f e r e n t i a l l y t o e a r l y f o r m e d s o l i d s w h e r e a s Rb was e n r i c h e d i n r e s i d u a l m e l t s as c r y s t a l l i z a t i o n p r o g r e s s e d . The t h e o r e t i c a l v a r i a t i o n o f t h e above e l e m e n t s were c a l c u l a t e d a t 1 0 p e r c e n t c r y s t a l l i z a t i o n i n t e r v a l s , w i t h i n i t i a l magma c o m p o s i t i o n o f 6 3 3 ppm Ba, 5 9 4 ppm S r and 5 3 ppm Rb. C a l c u l a t e d t r a c e e l e m e n t d a t a were p l o t t e d on d i a g r a m s o f S r v e r s u s Rb, S r v e r s u s Ba and Ba v e r s u s Rb on l o g a r i t h m i c p a p e r . T h e a c t u a l t r a c e e l e m e n t c o m p o s i t i o n d a t a o f i n d i v i d u a l 47 u n i t s of the Guichbn Creek b a t h o l i t h were then superimposed on c a l c u l a t e d t r e n d s . The r e s u l t s show that c r y s t a l f r a c t i o n a t i o n played a major r o l e during the c r y s t a l l i z a t i o n of Guichon Creek b a t h o l i t h even though the c r y s t a l l i z a t i o n of the b a t h o l i t h as a whole cannot be explained by a simple c r y s t a l l i z a t i o n model. 48 INTRODUCTION D i s t r i b u t i o n o f t r a c e e l e m e n t s i n i g n e o u s r o c k s d u r i n g m a g m a t i c d i f f e r e n t i a t i o n i s c o n t r o l l e d by a c o m b i n a t i o n o f c o m p l e x p r o c e s s e s , among w h i c h a r e : 1) t r a c e e l e m e n t c o m p o s i t i o n o f s o u r c e o f p a r e n t magma. 2) p r o c e s s e s by w h i c h t h e p a r e n t magma was e v o l v e d . 3) c r y s t a l l i z a t i o n and d i f f e r e n t i a t i o n p r o c e s s e s i n t h e p a r e n t magma. T r a c e e l e m e n t s a r e , as a r e s u l t , u s e d i n p e t r o g e n e t i c a n a l y s i s t o e v a l u a t e w h i c h o f t h e above p r o c e s s e s o r c o m b i n a t i o n o f them have been d o m i n a n t i n t h e f o r m a t i o n o f any s u i t e o f i g n e o u s r o c k s ( G a s t , 1968; P h i l p o t t s e t a l , 1970; M c C a r t h y e t a l , 1976; T i n d l e e t a l , 1 9 8 1; H i l d r e t h , 1 9 8 1 ; M i t t l e f e h l d l t , e t a l , 1 9 8 3 ) . T r a c e e l e m e n t s most u s e f u l i n t h e s e a n a l y s e s a r e t h o s e t h a t do n o t f o r m t h e i r own m i n e r a l s , b u t f o r m d i l u t e s o l u t i o n s i n b o t h m i n e r a l s and m e l t s . The a s s u m p t i o n o f d i l u t e s o l u t i o n s i m p l i f i e s t h e r m o d y n a m i c a n a l y s e s o f p a r t i t i o n i n g o f t r a c e e l e m e n t s b e t w e e n p h a s e s c o e x i s t i n g u n d e r e q u i l i b r i u m . D i l u t e s o l u t i o n s obey H e n r y ' s l a w , and t h u s t h e r m o d y n a m i c a c t i v i t y o f a t r a c e e l e m e n t w i l l be p r o p o r t i o n a l t o i t s mole f r a c t i o n . C o n c e n t r a t i o n o f any t r a c e e l e m e n t i n any two p h a s e s i n e q u i l i b r i u m c a n be a p p r o x i m a t e d f r o m t h e N e r s t d i s t r i b u t i o n c o e f f i c i e n t Kjj = C o n c e n t r a t i o n o f e l e m e n t i n pha s e A C o n c e n t r a t i o n o f e l e m e n t i n pha s e B A s i m p l e and d i r e c t u s e o f d i s t r i b u t i o n c o e f f i c i e n t s i s t h e r e c o n s t r u c t i o n o f t r a c e e l e m e n t c o n c e n t r a t i o n s i n a magma f r o m a n a l y s e s o f m i n e r a l s e q u i l i b r a t e d w i t h t h e magma. Most o f t h e d i s t r i b u t i o n c o e f f i c i e n t u s e d i n p e t r o g e n e n t i c m o d e l l i n g a r e d e r i v e d f r o m a n a l y s i s o f p h e n o c r y s t - m a t r i x p a i r s i n v o l c a n i c r o c k s ( P h i l p o t t s e t a l , 1970; A r t h 1976; H a n s o n , 1 9 7 8 ) . M i n e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t s v a r y c o n s i d e r a b l y w i t h b u l k c o m p o s i t i o n o f t h e m e l t and t e m p e r a t u r e and a r e l e s s d e p e n d e n t on p r e s s u r e v a r i a t i o n s ( Z i e l i n s k i , 1975; L o n g , 1 9 7 8 ) . The d e r i v a t i o n o f p h e n o c r y s t - m a t r i x p a r t i t i o n c o e f f i c i e n t s assumes t h a t e q u i l i b r i u m e x i s t e d d u r i n g t h e c r y s t a l l i z a t i o n o f any v o l c a n i c s u i t e ( D r a k e e t a l , 1 9 7 5 ) , a phenomenon t h a t v e r y r a r e l y h o l d s d u r i n g magmatic c r y s t a l l i z a t i o n as e v i d e n c e d by t h e common o c c u r r e n c e o f z o n e d c r y s t a l s . I t a l s o assumes v e r y e f f i c i e n t s e p a r a t i o n o f c r y s t a l s f r o m t h e m e l t f r o m w h i c h t h e y c r y s t a l l i z e d , s u c h t h a t e l e m e n t e x c h a n g e between m e l t and c r y s t a l s i s n e g l i g i b l e . V a r i a t i o n o f t r a c e e l e m e n t s d u r i n g c r y s t a l l i z a t i o n c a n be e v a l u a t e d by c o n s i d e r a t i o n o f two e x t r e m e m o d e l s : ( 1 ) p e r f e c t c r y s t a l l i z a t i o n o r R a y l e i g h f r a c t i o n a t i o n m o d e l . ( 2 ) A s u r f a c e e q u i l i b r i u m model i n w h i c h t h e s u r f a c e o f a g r o w i n g c r y s t a l m a i n -t a i n s e q u i l i b r i u m w i t h t h e m e l t . The f i r s t model i s d e s c r i b e d by t h e e q u a t i o n Cl_ = F®~^ Co 50 where C I = C o n c e n t r a t i o n o f e l e m e n t i n r e s i d u a l l i q u i d a f t e r r e m o v a l o f s o l i d c r y s t a l s e q u a l t o ( I - F ) o f t h e m e l t . Co = O r i g i n a l C o n c e n t r a t i o n o f t r a c e e l e m e n t i n magma. F = F r a c t i o n o f l i q u i d m e l t r e m a i n i n g . D = X i K d where X i = f r a c t i o n o f m i n e r a l i i n s o l i d and Kd = m i n e r a l - m e l t p a r t i t i o n c o e f -f i c i e n t ; i e . D i s t h e b u l k d i s t r i b u t i o n c o e f f e c i e n t i n v o l v i n g a l l t h e c r y s t a l s t h a t c o n c e n t r a t e t h e t r a c e e l e m e n t u n d e r c o n -s i d e r a t i o n . The s e c o n d model i s d e s c r i b e d by t h e e q u a t i o n C l / C o = 1/F+D(1-F) where a l l s y m b o l s a r e as d e s c r i b e d f o r t h e R a y l e i g h m o d e l . T h e r e a r e s e v e r a l o t h e r m o d i f i c a t i o n s o f t h e s e two m o d e l s , f o r e x a m p l e , m o d e l s t h a t t a k e i n t o a c c o u n t i n t e r s t i a l m e l t s ( M c l n t y r e , 1963; G r e e n l a n d , 1970) and i n c r e m e n t a l e q u i l i b r i u m model of M c C a r t h y and H a s t y , ( 1 9 7 6 ) . C r y s t a l l i z a t i o n o f p l u t o n i c r o c k s i s d i f f e r e n t f r o m t h a t assumed f o r v o l c a n i c r o c k s ( R a g l a n d and B u t l e r , 1972; M c C a r t h y and H a s t y , 1 9 7 6 ) . C r y s t a l l i z a t i o n r a t e i s s l o w e r i n p l u t o n i c r o c k s and t h e r e a r e more c r y s t a l c u m u l a t e s t h a n i n v o l c a n i c r o c k s , m e a n i n g t h a t a c o n s i d e r a b l e amount of l i q u i d m e l t w i l l be t r a p p e d b e t ween c r y s t a l s . D e p e n d i n g on t h e r a t e o f c r y s t a l l i z a t i o n o f t h e i n t e r s t i t i a l m e l t s i t s r e - e q u i l i b r i u m w i t h e n c l o s i n g c r y s t a l s c o u l d a l t e r t h e i r t r a c e e l e m e n t c o n c e n t r a t i o n c o n s i d e r a b l y , t h u s a f f e c t i n g m e a s u r e d p h e n o c r y s t - m a t r i x d i s t r i b u t i o n c o e f f i c i e n t s . T h u s , m o d e l l i n g 51 o f t r a c e eleme'ntfs v i n p l u t o n i c r o c k s c a n be a p p r o x i m a t e d by t r e a t i n g p l u t o n i c t r o c k s as m i x t u r e s o f c r y s t a l a c c u m u l a t e s and t r a p p e d r e s i d u a l m e l t ( T i n d l e e t a l , 1 9 8 1; M c C a r t h y & H a s t y , 1976; W h a l e n , 1983) T h i s s t u d y c o n s i d e r s t h e d i s t r i b u t i o n p a t t e r n s o f Ba, Rb and S r i n t h e c a l c - a l k a l i n e G u i c h o n C r e e k b a t h o l i t h i n s o u t h e a s t e r n B r i t i s h C o l u m b i a . B a , Rb and S r a r e s u i t a b l e f o r p a r t i t i o n i n g s t u d i e s i n p e t r o g e n e t i c a n a l y s i s o f g r a n i t o i d s y s t e m s , b e c a u s e d i s t r i b u t i o n c o e f f i c i e n t s o f t h e s e e l e m e n t s a r e w e l l known ( L o n g , 1978; P h i l p o t t s , e t a l , 1970; A r t h , 1976; H a n s o n , 1 9 7 8 ) ; and b e c a u s e t h e y a r e c o n c e n t r a t e d m a i n l y i n m a j o r m i n e r a l s r a t h e r t h a n i n a c c e s s o r y m i n e r a l s ( M c C a r t h y e t a l , 1 9 7 6 ) . M i t t l e f e h l d t e t a l , ( 1 9 8 3 ) c o n s i d e r s r a r e e a r t h e l e m e n t s t o be s u i t a b l e f o r p e t r o g e n e t i c s t u d i e s o f more m a f i c s y s t e m s , w h i l e B a, S r and Rb a r e more s u i t a b l e f o r g r a n i t i c and h i g h s i l i c a s y s t e m s . D e s p i t e t h e h i g h v a r i a b i l i t y o f t h e s e e l e m e n t s i n c a l c - a l k a l i n e s y s t e m s ( F e r s h t a t e r e t a l , 1 9 8 0 ) , c a r e f u l a n a l y s i s o f g e o c h e m i c a l d i s t r i b u t i o n p a t t e r n s i n t h e s e r o c k s c o u l d l e a d t o i n s i g h t i n t o d e t a i l s o f t h e d i f f e r e n t i a t i o n h i s t o r y . I n h y d r o u s s y s t e m s t h e use of t h e s e e l e m e n t s i n p e t r o g e n e t i c m o d e l l i n g s h o u l d t a k e i n t o a c c o u n t t h e i r more p r e f e r e n t i a l p a r t i t i o n i n g t o w a r d s an i m m i s c i b l e a q u e o u s p h a s e . PETROLOGY The p e t r o l o g y o f t h e G u i c h o n C r e e k b a t h o l i t h has been d i s c u s s e d by a number o f a u t h o r s ( N o r t h c o t e , 1969; M c M i l l a n , 52 1978; W e s t e r m a n , 1970; J o h a n and M c M i l l a n , 1 9 8 0 ) . Here o n l y t h e e s s e n t i a l p o i n t s t h a t may h e l p i n u n d e r s t a n d i n g t h e d i s t r i b u t i o n o f t r a c e e l e m e n t s , a r e r e v i e w e d b r i e f l y . The G u i c h o n C r e e k b a t h o l i t h i s a c o n c e n t r i c a l l y z o n e d body r a n g i n g i n c o m p o s i t i o n f r o m q u a r t z d i o r i t e a t t h e m a r g i n , t o q u a r t z m o n z o n i t e a t t h e c o r e . P e t r o g r a p h i c a l l y t h e b a t h o l i t h i c r o c k s c o n s i s t o f r e l a t i v e l y c o n s t a n t p r o p o r t i o n s o f p l a g i o c l a s e , q u a r t z , K - f e l d s p a r , b i o t i t e and h o r n b l e n d e w i t h r e l a t i v e l y m i n o r amounts o f a p a t i t e , m a g n e t i t e , s p h e n e , z i r c o n , and i n t h e B o r d e r p h a s e , a u g i t e . The a v e r a g e h o r n b l e n d e / b i o t i t e r a t i o d e c r e a s e s t o w a r d s t h e c o r e t h o u g h r e l a t i v e h o r n b l e n d e - b i o t i t e p r o p o r t i o n s do n o t v a r y a g r e a t d e a l . I n g e n e r a l , h o r n b l e n d e d e c r e a s e s f r o m 10 volume p e r c e n t i n t h e B o r d e r p h a s e t o 0.4 p e r c e n t i n t h e B e t h s a i d a p h a s e ( c o r e of b a t h o l i t h ) w h e r e a s b i o t i t e , a b o u t 10 v o l u m e p e r c e n t i n t h e B o r d e r p h a s e and i n t h e G u i c h o n v a r i e t y , t h e n d e c r e a s i n g t o 3 volume p e r c e n t i n B e t h s a i d a p h a s e . K - f e l d s p a r i s r e l a t i v e l y c o n s t a n t a t 10 w e i g h t p e r c e n t i n a l l p h a s e s e x c e p t t h e B o r d e r p h a s e i n w h i c h t h e m i n e r a l c o n s t i t u t e s a b o u t 3 volume p e r c e n t o f t h e r o c k . P l a g i o c l a s e i s a l s o r e l a t i v e l y c o n s t a n t i n amount t h r o u g h o u t t h e b a t h o l i t h , v a r y i n g by n o t more t h a n 5 volume p e r c e n t . B a t Rb AND S r DISTIRUBTION PATTERNS IN GUICHON CREEK BATHOLITH The a n a l y s i s o f t h e t h e o r e t i c a l c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k B a t h o l i t h was m o d e l l e d f o r b o t h R a y l e i g h f r a c t i o n a t i o n and s u r f a c e e q u i l i b r i u m m o d e l s w i t h a p a r e n t 53 magma c o n s i s t i n g p f Ba 633 ppm, Rb 53 ppm, and S r 594 ppm. The s e e s t i m a t e d a b u n d a n c e s i n t h e i n i t i a l G u i c h o n magma were c a l c u l a t e d by w e i g h t i n g a v e r a g e a b u n d a n c e s f o r i n d i v i d u a l p h a s e s o f t h e b a t h o l i t h by t h e r e l a t i v e a r e a s o f e x p o s u r e o f t h e p h a s e s . M o d e l l i n g was done w i t h a c o n s t a n t a v e r a g e modal m i n e r a l o g y c o n s i s t i n g o f p l a g i o c l o s e 50 p e r c e n t , K - f e l d s p a r 10 p e r c e n t , b i o t i t e 9 p e r c e n t , h o r n b l e n d e 8 p e r c e n t and q u a r t z 18 p e r c e n t . The m i n e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t s u s e d were t a k e n f r o m M c C a r t h y e t a l , ( 1 9 7 6 ) , P h i l p o t t s e t a l , ( 1 9 7 0 ) and A r t h , ( 1 9 7 6 ) . C r y s t a l l i z a t i o n t e m p e r a t u r e r a n g e i n t h e G u i c h o n C r e e k b a t h o l i t h i s c o n s i d e r e d t o have n o t v a r i e d by more t h a n 200°C t h r o u g h o u t t h e e n t i r e c r y s t a l l i z a t i o n . U nder t h e s e c o n d i t i o n s we c a n assume t h a t t h e t e m p e r a t u r e r a n g e was s m a l l and hence n e g l e c t t h e e f f e c t s o f t e m p e r a t u r e on d i s t r i b u t i o n c o e f f i c i e n t s . T h i s w o u l d a l l o w us t o use c o n s t a n t m i n e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t f o r t h e e n t i r e b a t h o l i t h i n t h e m o d e l l i n g o f t r a c e e l e m e n t s d i s t r i b u t i o n d u r i n g c r y s t a l l i z a t i o n . U s i n g m i n e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t s l i s t e d i n T a b l e 3-1, t h e b u l k d i s t r i b u t i o n c o e f f i c i e n t s f o r Ba, Rb and S r f o r e a c h phase were c a l c u l a t e d b a s e d on a v e r a g e m i n e r a l modes l i s t e d i n T a b l e 3-3. The c a l c u l a t e d b u l k d i s t r i b u t i o n s a r e l i s t e d i n T a b l e 3-2. R e s u l t s show t h a t t h e b u l k d i s t r i b u t i o n f o r s t r o n t i u m , D g r , i s more t h a n o ne, Dgb i s l e s s t h a n one w h e r e a s Dgg i s l e s s t h a n one i n t h e B o r d e r phase and more t h a n o r e q u a l t o one i n t h e r e m a i n d e r o f t h e b a t h o l i t h . The t h e o r e t i c a l i m p l i c a t i o n s o f t h e s e d i s t r i b u t i o n s c o e f f i c i e n t s i s t h a t s t r o n t i u m d e c r e a s e s w i t h i n c r e a s i n g 54 TABLE 3-1: MINERAL-MELT DISTRIBUTION C O E F F I C I E N T S 1 FOR ANDESTIC AND DACITIC VOLCANIC ROCKS Sr Ba Rb K P l a g i o c l a s e 2.84 0.36 0.048 0.263 K - f e l d s p a r 3.87 6.12 0.66 1.49* B i o t i t e 0.12 6.36 3.26 5.63* H o r n b l e n d e 0.22 0.044 0.014 0.33 Q u a r t z 0.0001 0.0001 0.0001 0.0001 * n o t r e a l l y d i s t r i b u t i o n c o e f f i c i e n t s i n t h e s e m i n e r a l s s i n c e K i s a m a j o r e l e m e n t . 1. C o m p i l e d f r o m A r t h , ( 1 9 7 6 ) ; P h i l p o t t s and S c h n e t z l e r , ( 1 9 7 0 ) ; and M c C a r t h y and H a s t y , ( 1 9 7 6 ) . TABLE 3-2: BULK DISTRIBUTION COEFFFICIENTS CALCULATED FROM MODAL MINERALOGY 2 OF EACH PHASE OF THE GUICHON CREEK BATHOLITH B o r d e r G u i c h o n Chataway B e t h l e h e m B e t h s a i d a P h a s e V a r i e t y V a r i e t y P hase Phase DSr 1.7085 1.84 1.98 1.79 1.91 DBa 0.8312 1.37 1.19 0.98 1.24 DRb 0.2758 0.385 0.2625 0.19 0.293 DK 0.592 0.794 0.593 0.45 0.64 2. Taken f r o m N o r t h c o t e , ( 1 9 6 9 ) s u m m a r i z e d i n T a b l e 3-3, u s i n g m i n e r a l - m e l t p a r t i t i o n c o e f f i c i e n t s l i s t e d i n T a b l e 4-1. TABLE 3-3 MODAL MINEROLOGY OF GUICHON CREEK BATHOLITH ROCKS CONSIDERED RESPONSIBLE FOR B a , S r AND Rb DISTRIBUTION PATTERNS B o r d e r G u i c h o n Chataway B e t h l e h e m B e t h s a i d a P h a s e V a r i e t y V a r i e t y P h a s e P h a s e P l a g i o c l a s e 55 50 54 49 52 K - f e l d s p a r 03 10 11 10 11 Q u a r t z 18 18 21 21 29 B i o t i t e 07 09 05 03 06 H o r n b l e n d e 10 08 07 04 0.4 93 85 98 87 98.4 a c i d i t y ( d i f f e r e n t i a t i o n ) ; i n c o n t r a s t , r u b i d i u m i n c r e a s e s . However, t h e D g a v a l u e i m p l i e s t h a t i n the Border phase , Ba s h o u l d i n c r e a s e w i t h i n c r e a s i n g d i f f e r e n t i a t i o n but f o r t he r e s t o f the b a t h o l i t h i t s h o u l d d e c r e a s e . F i g u r e 3 -1 shows p l o t s o f Ba v e r s u s Rb f o r each phase t o compare w i t h t r e n d s p r e d i c t e d by the b u l k d i s t r i b u t i o n c o e f f i c i e n t ( D g a ) . F i g u r e 3 - l ( a ) shows p o s i t i v e c o r r e l a t i o n of Ba and Rb c o n s i s t e n t w i t h D g a and D R J , o f l e s s t h a n 1 i n t he Border phase. The r e s t o f the b a t h o l i t h shows r e v e r s e t r e n d s , o f n e g a t i v e c o r r e l a t i o n between Ba v e r s u s Rb c o n s i s t e n t w i t h t r e n d s p r e d i c t e d by b u l k d i s t r i b u t i o n c o e f f i c i e n t s (D*3 a ) . 57 100 -i E a. a 5 0 ac (a) BO r 2 = 0 .304 100 • • • E a 3 50 • CC I -> — I ' 1 1 1 1 — - , — - T - — I 200 400 600 800 1000 1200 1400 (c) CH r 2 - 0 .077 100 E a a 50 or. Ba (ppm) (b) 100 -i •• 1 • 1 r r-—• 1 . 1 200 400 600 800 1000 1200 B a (ppm) (d) GU ° r 2 = 0.411 E a. 3 50 n or BE r 2 = 0.017 200 400 600 800 1000 1200 1400 Ba (ppm) i > i 1 r——i 1 1 1— 200 400 600 800 1000 1200 B a (ppm) Figure 3-1: Plots of Rb versus Ba i n major units of the Guichon Creek batholith; (a) Border phase; (b) Guichon variety; (c) Chataway variety; and (d) Bethsaida phase. In Border phase Rb i s correlated p o s i t i v e l y with Ba whereas i n other units of the batholith, these two elements are negatively correlated. 58 TRACE ELEMENT CONSTRAINTS ON CRYSTALLIZATION MODELS  OF THE GUICHON CREEK BATHOLITH I n m o d e l l i n g t r a c e e l e m e n t d i s t r i b u t i o n i n t h e G u i c h o n C r e e k b a t h o l i t h , c r y s t a l l i z a t i o n c a n be c o n s i d e r e d t o have c o n s i s t e d o f t h e r e m o v a l o f c o n s t a n t p r o p o r t i o n s o f 50 p e r c e n t p l a g i o c l a s e , 10 p e r c e n t p o t a s s i u m f e l d s p a r , 18 p e r c e n t q u a r t z , 9 p e r c e n t b i o t i t e and 8 p e r c e n t h o r n b l e n d e ( a v e r a g e modal m i n e r o l o g y o f G u i c h o n v a r i e t y o f t h e H i g h l a n d V a l l e y p h a s e ) . C a l c u l a t e d b u l k d i s t r i b u t i o n c o e f f i c i e n t s a r e D g a 1-37 ^Rb 0«385 and D g r 1.84. T h e o r e t i c a l d i s t r i b u t i o n s were c a l c u l a t e d f o r b o t h p e r f e c t and s u r f a c e e q u i l i b r i u m f r a c t i o n a t i o n m o d e l s , w i t h an a v e r a g e p a r e n t magma c o m p o s i t i o n of Ba 633 ppm, Rb 53 ppm and S r 594 ppm. The r e s u l t s a r e shown i n F i g u r e 3-2. as p l o t s o f S r v e r s u s Rb ( F i g . 3 - 2 ( a ) ) , Ba v e r s u s Rb ( F i g 3 - 2 ( b ) ) , and S r v e r s u s Ba ( F i g . 3 - 2 ( c ) ) . I n F i g u r e 3-2 s o l i d l i n e s AD, and d a s h e d l i n e BC r e p r e s e n t v a r i a t i o n o f t r a c e e l e m e n t d u r i n g R a y l e i g h f r a c t i o n a l c r y s t a l l i z a t i o n a t 10 p e r c e n t i n t e r v a l s , i n b o t h s o l i d and , c o e x i s t i n g m e l t r e s p e c t i v e l y . C u r v e s AB and BE r e p r e s e n t v a r i a t i o n o f t r a c e e l e m e n t s d u r i n g s u r f a c e e q u i l i b r i u m c r y s t a l l i z a t i o n , i n b o t h s o l i d and m e l t r e s p e c t i v e l y . , where A i s t h e c o m p o s i t i o n of t h e f i r s t s o l i d and B t h e c o m p o s i t i o n o f t h e p a r e n t magma. Thus i n s u r f a c e e q u i l i b r i u m c r y s t a l l i z a t i o n t h e c o m p o s i t i o n o f t h e s o l i d AB moves t o w a r d s t h e c o m p o s i t i o n of t h e p a r e n t magma, w i t h t h e l a s t s o l i d a t t a i n i n g t h e e x a c t p a r e n t magma c o m p o s i t i o n B. However, i n p l u t o n i c r o c k s as 59 Rb (ppm) Figure.3-2(a): Plot of Sr versus Rb showing theoretical d i f f e r e n t i a t i o n trends of the Guichon Creek batholith parent magma containing 594ppm Sr and 53ppm Rb. The s o l i d l i n e AD and broken l i n e BC, are s o l i d and residual melt compositional trends respectively, during perfect f r a c t i o n a l c r y s t a l l i z a t i o n . Curves AB and BE give s o l i d and residual melt compositional trends during surface equilibrium c r y s t a l l i z a t i o n respectively. Points A and B are i n i t i a l s o l i d and melt compositions respectively. 0 6a Figure.3-2(b): Plot of Ba versus Rb showing theoretical d i f f e r e n t i a t i o n trends of the Guichon Creek batholith parent containing 633ppm Ba and 53ppm Rb. Symbols as defined i n figure.3-2(a). 61 200 300 400 500 600 700 800 1000 Ba (ppm) Figure.3-2(c): Plot of Sr versus Ba showing theoretical d i f f e r e n t i a t i o n trends of the Guichon Creek batholith magma during perfect f r a c t i o n a l c r y s t a l l i z a t i o n . AB and CD are residual melt and s o l i d compositional trends respectively. 62. d i s c u s s e d a b o v e , p e r f e c t f r a c t i o n a t i o n i s r a t h e r r e s t r i c t e d s i n c e due t o t h e amount o f c r y s t a l s i n v o l v e d a s u b s t a n t i a l amount o f l i q u i d m e l t w o u l d be t r a p p e d b e t w e e n c r y s t a l s . The e f f e c t o f i n t e r s t i a l m e l t on t h e d i s t r i b u t i o n o f t r a c e e l e m e n t s d u r i n g c r y s t a l l i z a t i o n has been d i s c u s s e d e x t e n s i v e l y by G r e e n l a n d , ( 1 9 7 0 ) , and s p e c i f i c a l l y f o r g r a n i t i c p l u t o n i c r o c k s by M c C a r t h y and H a s t y , ( 1 9 7 6 ) . The r e l a t i v e amount o f t h i s i n t e r a c u m u l u s m e l t w o u l d e f f e c t t h e movement o f t h e s o l i d c o m p o s i t i o n ( l i n e AD) t o w a r d s t h e l i q u i d l i n e ( B E ) ( s e e M c C a r t h y and H a s t y , 1 9 7 6 ) . I n F i g 3-3, t h e a c t u a l t r a c e e l e m e n t c o m p o s i t i o n i s s u p e r i m p o s e d on t h e t h e o r e t i c a l d i s t r i b u t i o n s . Though t h e G u i c h o n C r e e k b a t h o l i t h t r a c e e l e m e n t d a t a show a r a t h e r b r o a d s c a t t e r , t h e m a j o r i t y o f s a m p l e s l i e b e t w e e n l i n e s AD and BE, w h i c h s u g g e s t s t h a t t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h c a n n o t be d e s c r i b e d by any s i m p l e c r y s t a l l i z a t i o n m o d e l . But t h e d i s t r i b u t i o n o f t h e d a t a p o i n t s , a l o n g t h e g e n e r a l t h e o r e t i c a l t r e n d s , s u g g e s t t h a t c r y s t a l f r a c t i o n a t i o n p l a y e d an i m p o r t a n t r o l e i n t h e c r y s t a l l i z a t i o n o f t h e b a t h o l i t h , and b o t h s u r f a c e e q u i l i b r i u m and R a y l e i g h f r a c t i o n a t i o n seem t o have o p e r a t e d e x t e n s i v e l y . The d i s t r i b u t i o n o f d a t a b e tween s o l i d and l i q u i d c o m p o s i t i o n l i n e AD and BC r e s p e c t i v e l y s u g g e s t t h a t v a r y i n g d e g r e e s o f i n t e r c u m u l u s m e l t e x i s t e d b e t ween c r y s t a l s f o r R a y l e i g h f r a c t i o n a l c r y s t a l l i z a t i o n . F i g . 3-3 a l s o shows t h a t c o m p o s i t i o n a l v a r i a t i o n i n t e r m s o f t r a c e e l e m e n t s b e tween p h a s e s a r e r a t h e r n a r r o w . However, F i g . 3 - 3 ( a ) and F i g . 3 - 3 ( b ) s u g g e s t t h a t t h e r e i s an e x p e c t e d g e n e r a l t r e n d o f d e c r e a s e i n 63 Rb (ppm) Figure 3-3(a): Sr versus Rb, Guichon Creek batholith data super-imposed on theoretical d i f f e r e n t i a t i o n trends as shown i n Figure 3-2. Real data though showing substantial scatter suggest that c r y s t a l fractionation controlled d i s t r i b u t i o n of Sr and Rb i n Border phase and Guichon variety ( s o l i d c i r c l e s and open c i r c l e s , respectively). In other phases, Rb decreased with progressive c r y s t a l l i z a t i o n due to preferential p a r t i t i o n i n g to v o l a t i l e phase that coexisting with the younger phases. Symbols are as defined i n Figure 3-2. 64 1000 900 -800 -700 ~ 600 -500 -E CL B 400 H CO DO 300 -200 1 3 Figure 3-3(b) I 2 0 I 3 0 4 0 5 0 ~"T— 6 0 7 0 I 8 0 9 0 1 0 0 Rb (ppm) Ba versus Rb data of the Guichon Creen batholith superimposed on theoretical d i f f e r e n t i a t i o n trends also shown i n Figure 3-2. The scatter of sample points along s o l i d composition l i n e AD suggest that c r y s t a l frac-tionation has contributed partly to the d i s t r i b u t i o n pattern of these elements. The occurrence of Border phase data ( s o l i d c i r c l e s ) around A of l i n e AD and Guichon variety data (open c i r c l e s ) towards D i s i n accord with c r y s t a l fractionation whereas occurrence of data for younger units indicates decrease of Rb with progressive c r y s t a l l i z a t i o n due to preferential p a r t i t i o n i n g towards the v o l a t i l e phase that coexisted with the younger phases. 65 200 300 400 500 600 700 800 1000 Ba (ppm) Figure 3-3(c) : Sr versus Ba, Guichon Creek batholith data superimposed on theoretical d i f f e r n t i a t i o n trends as shown in figure 3-2. Scatter of points around lines AB and C D suggest crystal fractionation occurrence, i n older units Border phase and Guichon variety s o l i d c i r c l e s and open c i r c l e s , respectively. In younger phases these elements were preferentially partitioned towards v o l a t i l e phase. Symbols as defined i n Figure 3-2. 66 S r and Ba f r o m the m a r g i n s o f t h e b a t h o l i t h ( B o r d e r P h a s e ) t o w a r d s t h e c o r e . F i g . 3 - 3 ( c ) i s r a t h e r a p o o r f i t ; e v e n t h o u g h t h e g e n e r a l t r e n d o f d e c r e a s i n g Ba and S r w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n i s o b s e r v e d i n b o t h t h e t h e o r e t i c a l model and a c t u a l d a t a , t h e s l o p e o f t h e t h e o r e t i c a l l y d e v e l o p e d t r a c e e l e m e n t s d i s t r i b u t i o n l i n e s a r e r a t h e r s t e e p w h e r e a s a c t u a l d a t a s u g g e s t a m o d e r a t e s l o p e w i t h S r v a r i a t i o n r a t h e r r e s t r i c t e d t h r o u g h o u t c r y s t a l l i z a t i o n . P e r h a p s one o f t h e p r o b l e m s c o u l d be due t o t h e w i d e v a r i a t i o n o f D g a i n G u i c h o n C r e e k b a t h o l i t h as compared t o D g r w h i c h i s a p p r o x i m a t e l y 2 f o r a l l t h e p h a s e s . S i n c e t h e G u i c h o n C r e e k b a t h o l i t h magma seems t o have been r e l a t i v e l y h y d r o u s , t h a t i s 2 t o 3 w e i g h t p e r c e n t w a t e r , t h e e f f e c t s o f an i m m i s c i b l e v o l a t i l e p hase on t h e d i s t r i b u t i o n o f Ba, Sr and Rb d u r i n g c r y s t a l l i z a t i o n c a n n o t be i g n o r e d . H owever, t r a c e e l e m e n t m o d e l l i n g i g n o r e s a v o l a t i l e p h a s e , hence e f f e c t s o f a v o l a t i l e p h a s e c a n n o t be a s s e s s e d f r o m p a t t e r n s d e v e l o p e d i n t h e p r e c e d i n g d i s c u s s i o n s . DISCUSSION T r a c e e l e m e n t s d i s t r i b u t i o n l a w s and d i s t r i b u t i o n c o e f f i c i e n t s s u g g e s t t h a t Ba i s c o n c e n t r a t e d i n K - f e l d s p a r and b i o t i t e b u t p r e f e r e n t i a l l y i n K - f e l d s p a r . Rb on t h e o t h e r hand i s c o n c e n t r a t e d i n b i o t i t e t o a g r e a t e r e x t e n t t h a n i n K - f e l d s p a r . C h a r g e d i f f e r e n c e R b + and B a + + a l s o s u g g e s t t h a t Ba w o u l d be c o n c e n t r a t e d more i n e a r l y K - f e l d s p a r t h a n i n l a t e 67 K - f e l d s p a r d i f f e r e n t i a t e s m e a n i n g Ba s h o u l d d e c r e a s e w i t h i n c r e a s i n g d i f f e r e n t i a t i o n . T h ese t r e n d s s u g g e s t t h a t K - f e l d s p a r w o u l d f r a c t i o n a t e Ba/Rb r a t i o more t h a n w o u l d b i o t i t e . T r e n d s o f Ba v e r s u s Rb i n ( F i g . 3-1) t h e r e f o r e c a n be e x p l a i n e d m a i n l y i n t e r m s o f K - f e l d s p a r v a r i a t i o n . K - f e l d s p a r v a r i e s f r o m 3 v o l u m e p e r c e n t i n t h e B o r d e r p h a s e t o an a v e r a g e o f 10 p e r c e n t i n t h e r e m a i n d e r o f t h e b a t h o l i t h . T h e r e f o r e t h e l o w D g a ( l e s s t h a n one) i n t h e B o r d e r p h a s e and t h e p o s i t i v e c o r r e l a t i o n o f Ba v e r s u s Rb ( F i g . 3 - l ( a ) ) c a n be e x p l a i n e d by t h e r e l a t i v e l y l o w K - f e l d s p a r c o n t e n t i n t h e B o r d e r phase compared t o t h e r e s t o f t h e b a t h o l i t h . The r e l a t i v e c o n s t a n c y o f S r i n t h e b a t h o l i t h as a w h o l e ( s e e F i g . 3 - 3 ( c ) ) ca n be e x p l a i n e d by s l i g h t v a r i a t i o n i n modal p l a g i o c l a s e , t h e main Sr c o n c e n t r a t o r . P l a g i o c l a s e v a r i e s by a b o u t 5 volume p e r c e n t t h r o u g h o u t t h e b a t h o l i t h ( T a b l e 3 - 3 ) . T h i s r e s u l t e d i n an a v e r a g e Dgj. o f a b o u t 2. Thus t h e d e p l e t i o n o f S r d u r i n g c r y s t a l l i z a t i o n was r e l a t i v e l y c o n s t a n t . The o t h e r e v i d e n c e w h i c h s u g g e s t s t h a t c r y s t a l f r a c t i o n a t i o n o p e r a t e d e x t e n s i v e l y d u r i n g t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h c a n be d e r i v e d f r o m F i g u r e 3-3 w h i c h i n d i c a t e s t h a t t h e G u i c h o n v a r i e t y i s t h e most e v o l v e d of t h e p r i n c i p a l r o c k u n i t s o f t h e b a t h o l i t h . T h i s can be e x p l a i n e d i n t e r m s o f c o m p a r a t i v e l y h i g h e r p r o p o r t i o n s o f p o t a s s i u m f e l d s p a r and b i o t i t e , t h e main c o n c e n t r a t o r s o f Ba and Rb. T h i s t r e n d t h e r e f o r e s u g g e s t s t h a t t r a c e e l e m e n t d i s t r i b u t i o n d u r i n g t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h i s m a i n l y t h e r e s u l t o f c r y s t a l f r a c t i o n a t i o n . However, b o t h R a y l e i g h f r a c t i o n a l and s u r f a c e e q u i l i b r i u m c r y s t a l l i z a t i o n s seem t o have o p e r a t e d d u r i n g c r y s t a l l i z a t i o n o f t h e b a t h o l i t h , t h u s s u g g e s t i n g t h a t i t s t r a c e e l e m e n t d i s t r i b u t i o n c a n n o t be e x p l a i n e d by any one s i m p l e c r y s t a l l i z a t i o n m o d e l . The r e l a t i v e l y h i g h c o n c e n t r a t i o n s o f Ba, S r and Rb i n t h e b a t h o l i t h s u g g e s t s d e r i v a t i o n o f t h e b a t h o l i t h magma f r o m s o u r c e s w i t h s i g n i f i c a n t amounts o f t h e s e e l e m e n t s . Though i n t e r m e d i a t e and g r a n i t i c r o c k s c o u l d t h e o r e t i c a l l y be d e r i v e d f r o m v a r i e d s o u r c e s , t r a c e e l e m e n t s e s p e c i a l l y Ba, S r and Rb c o u l d be u s e d as r o u g h d i s c r i m i n a n t s b e t w e e n t h e s e v a r i e d s o u r c e s ( F e r s h t a t e r e t a l , 1 9 8 0 ) . The l e v e l o f t h e s e e l e m e n t s i n G u i c h o n C r e e k b a t h o l i t h s u g g e s t t h a t t h e b a t h o l i t h magma may have been d e r i v e d f r o m o c e a n i c t h o l e i i t e s as s u g g e s t e d by O l a d e , ( 1 9 7 A ) on t h e b a s i s o f K/Rb r a t i o . H owever, i t seems t h a t t h e h i g h K/Rb r a t i o i s n o t o n l y a r e s u l t o f d e r i v a t i o n o f magma f r o m l o w K - s o u r c e , b u t i s due m a i n l y t o v o l a t i l e p hase a c t i v i t y d u r i n g c r y s t a l l i z a t i o n . T h i s i s c o n s i s t e n t w i t h an o b s e r v e d i n c r e a s e i n K/Rb r a t i o w i t h i n c r e a s i n g a c i d i t y o r p r o g r e s s i v e c r y s t a l l i z a t i o n . 69 CONCLUSION I n g e n e r a l F i g . 3-1 and 3-3 show g r e a t s c a t t e r i n t h e t r a c e e l e m e n t c o m p o s i t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h . T h i s may be t h e r e s u l t o f a number o f p r o c e s s e s u n r e l a t e d t o c r y s t a l l i z a t i o n , some o f w h i c h may be: 1) c h e m i c a l a n a l y s i s p r o b l e m s 2) s a m p l i n g p r o b l e m s 3) p r o b l e m s o f w e a t h e r i n g T h ese p r o b l e m s may be p r o n o u n c e d i n s i t u a t i o n s where more t h a n one s a m p l e r i s i n v o l v e d as i s t h e c a s e , w i t h t h e d a t a a t h a n d . D e s p i t e t h i s p r o b l e m s t h e G u i c h o n C r e e k b a t h o l i t h d a t a e x h i b i t i n t e r e s t i n g t r e n d s t h a t a r e r e a d i l y e x p l a i n a b l e as c r y s t a l l i z a t i o n e f f e c t s . Thus t h e r e s t r i c t e d t r a c e e l e m e n t c o m p o s i t i o n a l v a r i a t i o n o f t h e b a t h o l i t h r o c k s i s e x p e c t e d b e c a u s e t h e c o m p o s i t i o n a l v a r i a t i o n i s a l s o n a r r o w , r a n g i n g f r o m q u a r t z d i o r i t e t o q u a r t z m o n z o n i t e . As i s t h e c a s e i n o t h e r c a l c - a l k a l i n e r o c k s , t h e m i n e r a l o g i c a l r a n g e i s r a t h e r r e s t r i c t e d t o e x h i b i t w e l l p r o n o u n c e d f r a c t i o n a t e d p a t t e r n s o f a l k a l i and a l k a l i - e a r t h m e t a l s . The l a c k o f r a r e e a r t h e l e m e n t d a t a means t h a t o n l y c a u t i o u s c o n c l u s i o n s can be drawn f r o m t h i s s t u d y . R E E may have r e v e a l e d more c o n c l u s i v e t r e n d s o f c r y s t a l f r a c t i o n a t i o n p r o c e s s e s c o n t r o l l e d by h o r n b l e n d e and p l a g i o c l a s e , t h e two m i n e r a l s c o n s i d e r e d t o have p l a y e d a s i g n i f i c a n t r o l e i n t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h . D i s t r i b u t i o n p a t t e r n s o f B a , S r and Rb i n t h e G u i c h o n C r e e k b a t h o l i t h s u g g e s t t h a t c o m p o s i t i o n a l v a r i a t i o n i s t o a g r e a t e x t e n t t h e r e s u l t o f c r y s t a l f r a c t i o n a t i o n . C r y s t a l l i z a t i o n m o d e l s s u g g e s t t h a t p l a g i o c l a s e , h o r n b l e n d e , b i o t i t e and p o t a s s i u m f e l d s p a r p l a y e d an i m p o r t a n t r o l e i n t h e d i s t r i b u t i o n o f t h e s e e l e m e n t s . 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M i n i s t r y o f M i n e s and P e t r o l e u m R es. G e o l . F i e l d w o r k ( 1 9 7 4 ) p.27-34. J o h a n , Z., and M c M i l l a n W.J., 1980: P o s s i b i l i t i e s d' i n d i v i d u a l -i s a t i o n d'une phase f l u i d e a p a r t i r d'un b a i n s i l i c a t e : c o n s e q u e n c e s g e o c h i m i q u e s ; e x e m p l e du b a t h o l i t e de G u i c h o n C r e e k . Memoire du B.R.G.M. N° 99, p. 85-94. M i c h a e l , P . J . , 1983: C h i m i c a l D i f f e r e n t i a t i o n o f t h e B i s h o p T u f f and o t h e r H i g h - S i l i c a Magmas t h r o u g h C r y s t a l l i z a t i o n P r o c e s s e s . G e o l . , V . l l , p. 31-34. 73 M i l l e r , C . F . , 1 9 7 8 : M o n z o n i t i c P l u t o n s , C a l i f o r n i a : and a m o d e l f o r g e n e r a t i o n o f a l k a l i - r i c h n e a r s i l i c a - s a t u r a t e d magmas. C o n t r i b . M i n e r a l . P e t r o l . , V . 6 7 , p . 3 4 9 - 3 5 5 . M i t t l e f e h l d t , P . J . , and M i l l e r , C . F . , 1 9 8 3 : G e o c h e m i s t r y o f t h e S w e e t w a t e r Wash P l u t o n , C a l i f o r n i a : i m p l i c a t i o n s f o r " a n o m o l o u s " t r a c e e l e m e n t b e h a v i o u r d u r i n g d i f f e r e n t i a t i o n o f f e l s i c magmas. G e o c h i m . e t C o s m o c h i m . A c t a , V . 47 ( 1 ) , p . 1 0 9 - 1 2 4 . Neuman, H . , M e a d , J . , and V i t a l i a n o , C . J . , 1 9 5 4 : T r a c e E l e m e n t V a r i a t i o n D u r i n g F r a c t i o n a l C r y s t a l l i z a t i o n as C a l c u l a t e d f r o m t h e D i s t r i b u t i o n Law. G e o c h i m . e t C o s m o c h i m . A c t a , V . 6 , p . 9 0 - 9 9 . Northcote, K . E . , 1 9 6 9 : G e o l o g y and G e o c h r o n o l o g y o f t h e G u i c h o n C r e e k B a t h o l i t h . B . C . M i n i s t r y o f M i n . & P e t . R e s . B u l l . , 5 6 . N o y e s , H . J . , F r e y , F . A . , and Wones , D . R . , 1 9 8 3 : A T a l e o f Two P l u t o n s : G e o c h e m i c a l E v i d e n c e B e a r i n g on t h e O r i g i n and D i f f e r e n t i o n o f t h e R e d l a k e and E a g l e Peak P l u t o n s ; C e n t r a l S i e r r a N e v a d a , C a l i f o r n i a . J . G e o l . , V . 9 1 ( 5 ) , p . 4 8 7 - 5 0 9 . O l a d e , M . A . D . , 1 9 7 4 : B e d r o c k G e o c h e m i s t r y o f P o r p h y r y C o p p e r D e p o s i t s , H i g h l a n d V a l l e y , B . C . P h D . t h e s i s , U n i v e r s i t y o f B r i t i s h C o l u m b i a ( U n p u b l i s h e d ) . P h i l p o t t s , J . A . , and S c h n e t z l e r , C . C . , 1 9 7 0 : P h e n o c r y s t -M a t r i x P a r t i t i o n C o e f f i c i e n t s f o r K, R b , S r , and Ba w i t h A p p l i c a t i o n s to A n o r t h o s i t e and B a s a l t G e n e s i s . G e o c h i m . e t C o s m o c h i m . A c t a , V . 3 4 , p . 3 0 7 - 3 2 2 . R a g l a n d , P . C . , and B u t l e r , J . R . , 1 9 7 2 : C r y s t a l l i z a t i o n o f t h e West F a r r i n g t o n P l u t o n , N o r t h C a r o l i n a , U . S . J . P e t r o l . , V . 1 3 , p . 3 8 1 - 4 0 4 . T i n d l e , A . G . , and P e a r c e , J . A . , 1 9 8 1 : P e t r o g e n e t i c M o d e l l i n g o f i n s i t u F r a c t i o n a l C r y s t a l l i z a t i o n i n t h e Z o n e d L o c k Doon P l u t o n , S c o t l a n d . C o n t . M i n e r a l . P e t r o l . , V . 7 8 , p . 1 9 6 - 2 0 7 . W e s t e r m a n , C . J . , 1 9 7 0 : A P e t r o g e n i c S t u d y o f t h e G u i c h o n C r e e k B a t h o l i t h , B . C . M s c . t h e s i s U n i v e r . o f B . C . ( U n p u b l i s h e d ) . 74 W h a l e n , J . B . , 1983: The A c k l e y C i t y B a t h o l i t h , S o u t h e a s t e r New-f o u n d l a n d : e v i d e n c e f o r c r y s t a l v e r s u s l i q u i d s t a t e f r a c t i o n a t i o n . G e o c h i m . e t Cosmochim. A c t a , V. 4 7 ( 8 ) , p. 1443-1457. Z i e l i n s k i , R.A., 1975: T r a c e e l e m e n t e v a l u a t i o n o f a s u i t e o f r o c k s f r o m R e u n i o n I s l a n d , I n d i a n O c e a n . G e o c h i m . e t Cosmo., A c t a , V.39, p.713-734. 75 CHAPTER FOUR VARIATION OF K/Rb RATIO IN THE MAJOR UNITS  OF THE GUICHON CREEK BATHOLITH ABSTRACT R u b i d i u m has a l a r g e r i o n i c r a d i u s t h a n p o t a s s i u m w h i c h i t s u b s t i t u t e s e x t e n s i v e l y i n K - b e a r i n g m i n e r a l s d u r i n g c r y s t a l l i z a t i o n o f s i l i c a t e magmas. B e c a u s e o f t h e s e r e l a t i o n s t h e K/Rb r a t i o i n s i l i c a t e r o c k s d e c r e a s e s w i t h i n c r e a s i n g a c i d i t y . I n t h e G u i c h o n C r e e k b a t h o l i t h , t h e K/Rb r a t i o i n c r e a s e s t o w a r d s t h e c e n t r e o f t h e b a t h o l i t h ( w i t h i n c r e a s i n g a c i d i t y ) w i t h v a l u e s r a n g i n g f r o m 341 t o 800. The t r e n d and w i d e v a r i a t i o n s o f K/Rb r a t i o i n G u i c h o n C r e e k b a t h o l i t h r o c k s a r e a t t r i b u t e d t o l a t e s t a g e v o l a t i l e p hase i m m i s c i b i l i t y and t h e f a c t t h a t r u b i d i u m i s more s o l u b l e t h a n p o t a s s i u m i n a v o l a t i l e p h a s e . 76 INTRODUCTION C l o s e g e o c h e m i c a l a s s o c a t i o n o f p o t a s s i u m and r u b i d i u m has l e d t o t h e e x t e n s i v e use of K/Rb r a t i o i n p e t r o g e n i c a n a l y s i s of i g n e o u s s y s t e m s . T h e i r i o n i c r a d i i do n o t d i f f e r by more t h a n 15 p e r c e n t ( K + = 1.33A and R b + = 1.47A)and Rb as a minor e l e m e n t s u b s t i t u t e s e x t e n s i v e l y f o r K + s i t e s i n K - b e a r i n g m i n e r a l s , e s p e c i a l l y i n m i c a s w h i c h have l a r g e r K + s i t e s t h a n do f e l d s p a r s . Because of i t s g e o c h e m i c a l s i m i l a r i t y t o K, t h e d i s t r i b u t i o n of Rb d u r i n g magmatic p r o c e s s e s i s c o n t r o l l e d m a i n l y by a v a i l a b i l i t y of K s i t e s . B e i n g l a r g e r i n s i z e , Rb a c c u m u l a t e s g e n e r a l l y more r a p i d l y t h a n K i n r e s i d u a l m e l t s , b e c a u s e abundant K - b e a r i n g m i n e r a l s a r e m o s t l y l a t e d i f f e r n e t i a t e s . Hence, i n p r o g r e s s i v e d i f f e r e n t i a t i o n t h e K/Rb of r o c k s s h o u l d d e c r e a s e w i t h i n c r e a s i n g a c i d i t y . K/Rb r a t i o s t h u s can be i n d i c a t i v e of t h e e x t e n t or d i r e c t i o n o f d i f f e r e n t i a t i o n i n a s u i t e of i g e n o u s r o c k s . The K/Rb r a t i o of o c e a n i c v o l c a n i c r o c k s d e c r e a s e s from 1300 i n o c e a n i c t h o l e i i t e s to about 350 i n a l k a l i b a s a l t s and as low as 300 i n t r a c h y t e s ( E n g e l e t a l , 1965). In o r g e n i c a n d e s i t e s the K/Rb r a t i o d e c r e a s e s w i t h i n c r e a s i n g K or a c i d i t y ( G i l l , 1 9 7 8 ). The a v e r a g e K/Rb r a t i o r ange of c r u s t a l r o c k s i s between 130 t o 300 ( T a y l o r , 1 9 65). The K/Rb r a t i o i n i g n e o u s r o c k s can be used t o d i s t i n g u i s h d i f f e r e n t magmatic p r o c e s s e s t h a t may have a f f e c t e d a p a r t i c u l a r s u i t e ; f o r example, p r o c e s s e s r e l a t e d t o s o u r c e of p a r e n t magma, the e x t e n t and t r e n d o f magmatic d i f f e r e n t i a t i o n . H ere we c o n s i d e r t h e a n o m a l o u s K/Rb r a t i o s i n r o c k s o f t h e G u i c h o n C r e e k b a t h o l i t h . S i n c e m a j o r e l e m e n t c h e m i s t r y , f i e l d e v i d e n c e and phase e q u i l i b r i a show t h a t t h e G u i c h o n C r e e k b a t h o l i t h i s a h i g h l y d i f f e r e n t i a t e d c o m p o s i t e body r a n g i n g f r o m q u a r t z - d i o r i t e a t t h e m a r g i n t o q u a r t z m o n z o n i t e t o w a r d s t h e c o r e t h e K/Rb r a t i o w o u l d be e x p e c t e d t o d e c r e a s e w i t h i n c r e a s i n g a c i d i t y . However, t h e K/Rb r a t i o o f G u i c h o n r o c k s does n o t f o l l o w t h i s e x p e c t e d t r e n d , i n s t e a d t h e r a t i o i n c r e a s e s w i t h i n c r e a s i n g a c i d i t y ( F i g . 4 - 1 ) . Few s i m i l a r K/Rb r a t i o t r e n d s have been r e p o r t e d i n t h e l i t e r a t u r e , one e x a m p l e b e i n g t h e B l u e M o u n t a i n N e p h e l i n e S y e n i t e i n O n t a r i o ( P a y n e and Shaw, 1 9 6 7 ) . B e s i d e s t h e a n o m a l o u s t r e n d i n t h e G u i c h o n C r e e k b a t h o l i t h , K/Rb r a t i o l e v e l s a r e a b n o r m a l l y h i g h ; e x c l u d i n g t h e B o r d e r p h a s e w i t h a r a t i o o f 3 4 1 , t h e r a n g e i s 300 t o o v e r 800, ( T a b l e 4 - 1 ) . Compared t o t h e K/Rb r a t i o s c a l c u l a t e d f r o m t h e o r e t i c a l c o n c e n t r a t i o n s o f K and Rb, d e r i v e d u s i n g e q u i l i b r i u m f r a c t i o n a t i o n m o d e l s ( T a b l e 4 - 1 ) , t h e K/Rb r a t i o s r a n g e i n t h e G u i c h o n C r e e k b a t h o l i t h r o c k s i s w i d e r , t h u s s u g g e s t i n g t h e t r e n d was c a u s e d by p r o c e s s e s o t h e r t h a n c r y s t a l f r a c t i o n a t i o n . 250 J 1 - i : — i 1 1.5 2.0 2.5 3.0 K (Wt. %) Figure.4-1: A plot of average K/Rb r a t i o s of major units of the Guichon Creek batholith versus K(weight percent). The average r a t i o decreases from 341 i n Border phase to 333 in Guichon variety and then increases with progressive c r y s t a l l i z t i o n to greater than 800 i n Bethsaida phase. B0= Border phase; GU ts Guichon variety; CH = Chataway variety; BL = Bethlehem phase and BE = Bethsaida phase. 79 K-Rb RELATIONS IN GUICHON CREEK BATHOLITH ROCKS C o m p o s i t i o n a l l y , t h e G u i c h o n C r e e k B a t h o l i t h p a r e n t magma i s a p p r o x i m a t e l y a n d e s i t i c , w i t h S i 0 2 a b o u t 63 w e i g h t p e r c e n t . The l a r g e l i t h o p h i l e e l e m e n t s s u c h as Rb show a v e r y w i d e r a n g e o f v a l u e s i n a n d e s i t i c and o t h e r c a l c - a l k a l i n e r o c k s , d e p e n d e n t m o s t l y on t h e s o u r c e o f p a r e n t magma. F o r t h e G u i c h o n C r e e k b a t h o l i t h a v e r a g e Rb c o m p o s i t i o n r a n g e s f r o m 52 ppm i n t h e G u i c h o n v a r i e t y t o a r o u n d 34 ppm i n t h e B e t h s a i d a p h a s e . T h i s p a t t e r n i s shown i n ( F i g . 4-2) w h i c h a l s o shows t h a t i n g e n e r a l , Rb i n c r e a s e s w i t h i n p h a s e s w i t h i n c r e a s e i n s i l i c a , w h e r e a s t h e g e n e r a l t r e n d f o r t h e b a t h o l i t h i s d e c r e a s i n g Rb c o n t e n t w i t h i n c r e a s i n g s i l i c a . DISCUSSION S e v e r a l mechanisms have been s u g g e s t e d t h a t c o u l d f r a c t i o n a t e p o r a s s i u m and r u b i d i u m and l e a d t o i n c r e a s e i n K/Rb r a t i o w i t h p r o g r e s s i v e d i f f e r e n t i a t i o n . ( 1 ) M i c a f r a c t i o n a t i o n ( W h i t e , 1966) ( 2 ) O l i v i n e , C l i n o p y r o x e n e and g a r n e t f r a c t i o n a t i o n ( J a k e s and W h i t e 1970) ( 3 ) A m p h i b o l e f r a c t i o n a t i o n ( H a r t and A l d r i c h , 1 9 6 7 ) . ( 4 ) E f f e c t o f aqueous p h a s e ( P a y n e and Shaw, 1967) S i0 2 (Wt. %) Figure 4-2: Rb v/s SiO^, Guichon Creek batholith. Solid c i r c l e s are Border phase; open c i r c l e s are Guichon variety; s o l i d inverted triangles are Chataway variety and s o l i d squares are Bethsaida phase. Arrows indicate increasing Rb with increasing SiG^ within individual phases, and a general decrease i n Rb with increasing SiO„ i n the batholith as a whole. TABLE 4-1 VARIATION OF POTASSIUM (K i n Wt %) AND RUBIDIUM (Rb i n ppm), AND K/Rb RATIO IN GUICHON CREEK BATHOLITH ROCKS. STARRED COLUMNS CONTAIN VALUES CALCULATED FROM THE RAYLEIGH FRACTIONATION MODEL, WITH THE ONE STAR CONTAINING K, Rb AND K/Rb RATIO CALCULATED USING THE ACTUAL MODAL MINERALOGY OF GUICHON BATHOLITH ROCKS; AND TWO STARS FROM ADJUSTED MINERALOGY TO PRODUCE THE K/Rb RATIO TREND OF BATHOLITH ROCKS S i 0 2 K Rb K/Rb K* Rb* K/Rb* K** Rb** K/Rb** B o r d e r Phase 58.9 1 .33 39 341 1.66 33 503 1.78 38 468 G u i c h o n V a r i e t y 61.8 1 .73 52 333 2.01 48 419 1.80 38 474 Chataway V a r i e t y 64.2 1 .75 47 372 2.01 50 402 1.81 37 489 B e t h l e h e m V a r i e t y 65.2 1 .85 38 487 1.89 47 402 1.93 38 509 B e t h s a i d a Phase 73.7 2 .83 34 832 2.70 73 370 1.89 37 511 TABLE 4-2 ORIGINAL MODAL MINERALOGY USE IN CALCULATING K/Rb TREND m i n e r a l s B o r d e r G u i c h o n Chataway B e t h l e h e m B e t h s a i d a P h a s e V a r i e t y V a r i e t y P h ase P h a s e P l a g i o c l a s e 55 50 54 49 52 K - f e l d s p a r 3 10 11 10 11 Q u a r t z 18 18 21 21 29 B i o t i t e 7 9 5 3 6 H o r n b l e n d e 10 8 7 4 0.4 K/Rb 503 419 402 402 370 (MINERAL MODES PROPORTIONS WERE ADJUSTED TO PRODUCE K/Rb TREND OF BATHOLITHIC ROCKS) P l a g i o c l a s e 50 50 50 48 50 K - f e l d s p a r 3 10 7 7 6 B i o t i t e 9 6 3 2 2 H o r n b l e n d e 38 34 40 43 42 K/Rb 468 474 489 509 511 Of t h e s e p r o c e s s e s , t h e s e c o n d does n o t a p p l y t o t h e G u i c h o n C r e e k b a t h o l i t h b e c a u s e t h e m i n e r a l s s p e c i f i e d a r e e i t h e r n o t p r e s e n t o r o c c u r as m i n o r m i n e r a l p h a s e s . P r o c e s s e s ( 1 ) and ( 3 ) were m o d e l l e d t h e o r e t i c a l l y u s i n g d i s t r i b u t i o n c o e f f i c i e n t s o f a n d e s i t i c r o c k s f o r t h e s e e l e m e n t s . The d i s t r i b u t i o n c o e f f i c i e n t s o f K and Rb u s e d i n m o d e l l i n g a r e 5.63 and 3.26 i n b i o t i t e s and 0.33 and 0.014 i n h o r n b l e n d e r e s p e c t i v e l y ( P h i l p o t t s and S c h n e t z l e r , 1 9 7 0 ) . From t h e s e f i g u r e s , c o m p a r a t i v e K/Rb r a t i o s f o r b i o t i t e s a r e a b o u t 2 and f o r h o r n b l e n d e a b o u t 23. T h e r e f o r e , m i c a f r a c t i o n a t i o n c o u l d n o t l e a d t o any a p p r e c i a b l e i n c r e a s e i n K/Rb r a t i o , and hence c a n n o t a c c o u n t f o r t h e o b s e r v e d K/Rb v a r i a t i o n o f t h e G u i c h o n r o c k s . V a r i a t i o n i n a m p h i b o l e c o n t e n t , on t h e o t h e r h a n d , w i t h a l a r g e r K/Rb r a t i o c o u l d i n d e e d l e a d t o s y s t e m i c c h a n g e s i n K/Rb r a t i o . H owever, w i t h t h e modal m i n e r a l o g y o f t h e G u i c h o n C r e e k r o c k s , t o p r o d u c e t h e o b s e r v e d t r e n d w o u l d need much h i g h e r f r a c t i o n s o f a m p h i b o l e t h a n o b s e r v e d ( T a b l e 4 - 2 ) . T h i s t h e r e f o r e s u g g e s t s t h a t t h e K/Rb r a t i o i n G u i c h o n r o c k s c o u l d n o t be o n l y t h e r e s u l t o f t h e c o m b i n e d b i o t i t e - h o r n b l e n d e f r a c t i o n a t i o n b u t some o t h e r p r o c e s s seems t o be s u p e r i m p o s e d on c r y s t a l l i z a t i o n p r o c e s s e s . The o n l y o t h e r p r o c e s s w h i c h n e e d s e x p l o r i n g i n d e t a i l i s t h e p r o c e s s l i s t e d f o u r t h a b o v e ; e f f e c t s o f an a q u e o u s p h a s e . The e f f e c t o f an a q u e o u s p h a s e i s v e r y d i f f i c u l t t o document b e c a u s e d i s t r i b u t i o n c o e f f i c i e n t s o f K and Rb b e t w e e n s i l i c a t e m e l t and a q u e o u s p h a s e a r e n o t a v a i l a b l e . However, t h e r e l a t i v e d i s t r i b u t i o n o f t h e s e two e l e m e n t s c a n be i n f e r r e d f r o m , t h e i r g e n e r a l c h e m i s t r y . Rb has l o w e r m e l t i n g and b o i l i n g p o i n t s , c ompared t o p o t a s s i u m . H ence, Rb g a s i f i e s more r e a d i l y t h a n p o t a s s i u m ( R b ( s ) > R b ( g ) ) . These c h a r a c t e r i s t i c s o f Rb r e s u l t s i n i t s e n t e r i n g t h e v o l a t i l e p hase more r e a d i l y t h a n does p o t a s s i u m . T h u s , a v a p o u r p h a s e c a n c a u s e f r a c t i o n a t i o n b e t w e e n p o t a s s i u m and r u b i d i u m . The p a r t i t i o n i n g o f r u b i d i u m more r e a d i l y t o a v o l a t i l e p h a s e d e p l e t e s r e s i d u a l m e l t o f r u b i d i u m t h u s l e a d i n g t o an i n c r e a s e o f K/Rb r a t i o w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n i n r e s i d u a l m e l t . B e c a u s e o f t h e b e h a v i o u r o f v o l a t i l e p h a s e , f o r e x a m p l e , r a p i d r e l e a s e , t h e e f f e c t s on t h e K/Rb r a t i o c o u l d be w i d e l y v a r i a b l e w i t h v e r y h i g h r a t i o s : b o t h t h e s e f e a t u r e s a r e o b s e r v e d i n t h e G u i c h o n C r e e k b a t h o l i t h . CONCLUSION Though e x p e r i m e n t a l e v i d e n c e i s v e r y much needed t o c o n f i r m e m p i r i c a l e v i d e n c e a b o u t t h e e f f e c t o f an a q u e o u s p h a s e on t h e K/Rb r a t i o i n magmatic s y s t e m s , i t seems l i k e l y t h a t K/Rb r a t i o c a n be u s e d t o i n d i c a t e v o l a t i l e p h a s e a c t i v i t y i n s i l i c a t e m e l t s . The t r e n d o f K/Rb r a t i o s u g g e s t t h a t t h e magma c o n t a i n e d a h i g h w a t e r c o n t e n t r e s u l t i n g i n e a r l y s a t u r a t i o n ; h e n c e , t h e K/Rb r a t i o i s an i n d i r e c t d i a g n o s t i c f a c t o r o f d e g r e e o f d i f f e r e n t i a t i o n . I n t h e G u i c h o n C r e e k b a t h o l i t h , t h e w a t e r c o n t e n t was e s t i m a t e d b e t w e e n 2 and 3 w e i g h t p e r c e n t . S a t u r a t i o n was r e a c h e d a f t e r a b o u t 72 p e r c e n t c r y s t a l l i z a t i o n , w h i c h c o i n c i d e s w i t h c o m p l e t i o n o f c r y s t a l l i z a t i o n o f t h e H i g h l a n d V a l l e y p h a s e . The t i m i n g o f v o l a t i l e p hase r e l e a s e d u r i n g m agmatic d i f f e r e n t i a t i o n i s v e r y i m p o r t a n t i n u n d e r s t a n d i n g t h e r e s u l t a n t h y d r o t h e r m a l s y s t e m s . 86 REFERENCES E w a e r t , A., and S t i p p , J . J . , 1968: P e t r o g e n e s i s o f t h e V o l c a n i c R o c k s o f t h e C e n t r a l N o r t h New Z e a l a n d as i n d i c a t e d by a s t u d y o f ^ S r / o ^ S r r a t i o s and S r , Rb, K, U and, Th a b u n d a n c e s . G e o c h i m . e t Cosmochim. A c t a , V.32, P.699-736. T e r r e s t i a l R a t i o o f P o t a s s i u m t o R u b i d i u m and t h e C o m p o s i t i o n o f t h e M a n t l e . S c i e n c e , V. 147, p.858. R o l e o f T r a c e E l e m e n t s P a r t i t i o n C o e f f i c i e n t s i n M o d e l s o f A n d e s i t e G e n e s i s . G e o c h i m . e t Cosmochim A c t a , V. 42, p. 709-724. H a n s o n , G.N., and L o n g m u i r , D.H., 1978: M o d e l l i n g o f M a j o r E l e m e n t s i n M a n t l e - M e l t S y s t e m s U s i n g T r a c e E l e m e n t s A p p r o a c h e s . G e o c h i m . e t Cosmochim. A c t a , V. 4 2 , p. 72 5 - 7 4 1 . H a r t s , S.R., and A l d r i c h , L.T. 1967: F r a c t i o n a t i o n o f P o t a s s i u m / R u b i d i u m by A m p h i b o l e s : I m p l i c a t i o n s R e g a r d i n g M a n t l e C o m p o s i t i o n . S c i e n c e , V.155, p. 325-327. H e i e r , K.S., 1966: Some C r y s t a l l o - C h e m i c a l R e l a t i o n s o f N e p h e l i n e s and F e l d s p a r s o f S t j e s n o y , N o r t h Norway J . P e t r o l . , V. 7, p. 9 5 - 1 1 3 . J a k e s , P., and W h i t e , A.J.R., 1970: K/Rb R a t i o o f R o c k s From I s l a n d A r c s . G e o c h i m . e t Cosmochim., B.34, p. 849-856. L a n g e , I.M., R e y n o l d s , R.C., and L y o n s , J . B . , 1966; K /Rb R a t i o s i n C o e x i s t i n g K - f l e d s p a r s and B i o t i t e s f r o m some New E n g l a n d G r a n i t e s and M e t a s e d i m e n t s . C o n t r i b . m i n e r a l , P e t r o l . , V . l , p. 317-322. M i t t l e f e h l d t , D.W., and M i l l e r , C.F., 1983: G e o c h e m i s t r y o f t h e S w e e t w a t e r Wash P l u t o n , C a l i f o r n i a : I m p l i c a t i o n s o f a n o m a l o u s t r a c e e l e m e n t s b e h a v i o u r d u r i n g d i f f e r e n t i a t i o n o f f e l s i c magmas. Geochim. e t Cosmochim. A c t a , V. 4 7 ( 1 ) , p .109-124. G a s t , P.W., 1965: G i l l , J . B . , 1978: Pa y n e , J.G., and Shaw, D.M. 1967: K-Rb R e l a t i o n s i n t h e B l u e 87 M o u n t a i n N e p h e l i n e S y e n i t e . E a r t h . P l a n e t . S c i . L e t t . , V.2, P. 2 90-292. P h i l p o t t s , J.A., and S c h n e t z l e r , C.C., 1970: P h e n o c r y s t -m a t r i x p a r t i t i o n o e f f i c i e n t s f o r K, Rb, S r , and Ba w i t h a p p l i c a t i o n s t o a n o r t h o s i t e and b a s a l t g e n e s i s . S c i e n c e , V. 147, p. 8 5 8 - 8 6 0 . O l a d e , M.A., and F l e t c h e r , W.K., 1975: P r i m a r y D i s p e r s i o n o f R u b i d i u m and S t r o n t i u m A r o u n d P o r p h y r y C o p p e r D e p o s i t s , H i g h l a n d V a l l e y , B r i t i s h C o l u m b i a . E c o n . G e o l . , V. 70, p. 1 5 - 2 1 . R i n g w o o d , A.E., 1955: The P r i n c i p l e s G o v e r n i n g T r a c e E l e m e n t s B e h a v i o u r d u r i n g M a g m a t i c C r y s t a l l i z a t i o n . P a r t I I . The r o l e o f Complex F o r m a t i o n . G e o c h i m . e t Cosmochim. A c t a , V. 7, p. 242-254. Shaw, D.M., 1968: A r e v i e w o f K-Rb f r a c i o n a t i o n t r e n d by c o -v a r i e n c e a n a l y s i s . G e o c h i m . e t Cosmochim. A c t a , V. 32, p. 5 7 3 - 6 0 1 . T a y l o r , S.R., 1965: The A p p l i c a t i o n o f T r a c e E l e m e n t D a t a t o P r o b l e m s i n P e t r o l o g y . P h y s . and Chem. o f t h e E a r t h , V. 6, p. 1 33-213. CHAPTER F I V E  DISTRIBUTION OF C r , Co. N i , Cu. AND Zn ABSTRACT B u l k d i s t r i b u t i o n c o e f f i c i e n t s (D) f o r t h e e l e m e n t s C r , Co, N i , Cu and Zn i n t h e m a j o r u n i t s o f t h e G u i c h o n C r e e k b a t h o l i t h r a n g e f r o m 3 i n t h e o l d e r p h a s e s t o b e l o w one i n y o u n g e r p h a s e s , i n d i c a t i n g p r e f e r e n t i a l p a r t i t i o n i n g o f t h e s e e l e m e n t s i n e a r l y c r y s t a l l i z e d s o l i d s . The h i g h e s t d i s t r i b u t i o n c o e f f i c i e n t s o c c u r i n t h e G u i c h o n v a r i e t y , t h e s e c o n d m a j o r u n i t o f t h e b a t h o l i t h t o c r y s t a l l i z e , T)QT = 3.5, D N i = 3 . 0 0 , D C o = 1.78, D C u = 1.51 and D Z n = 1.11. The r e l a t i v e m a g n i t u d e o f t h e "D" v a l u e s i n d i c a t e s t h e o r d e r o f e n r i c h m e n t o f t h e s e e l e m e n t s i n t o c r y s t a l l i z i n g s o l i d . Chromium, n i c k e l and c o b a l t have t h e h i g h e s t v a l u e s f o l l o w e d by c o p p e r and z i n c , w h i c h i s c o n s i s t e n t w i t h t h e o r d e r o f p a r t i t i o n i n g o f t r a n s i t i o n e l e m e n t s i n o c t a h e d r a l e n v i r o n m e n t s p r e d i c t e d by c r y s t a l f i e l d t h e o r y . I n y o u n g e r u n i t s o f t h e G u i c h o n C r e e k b a t h o l i t h D v a l u e s of t h e above e l e m e n t s a r e b e l o w one s u g g e s t i n g i n t h e s e y o u n g e r p h a s e s t h e s e e l e m e n t s were p a r t i t i o n i n g s u b s t a n t i a l l y t o t h e s i l i c a t e m e l t r e l a t i v e t o c r y s t a l l i z i n g s o l i d s i n c o n t r a s t t o 89 d i s t r i b u t i o n i n o l d e r p h a s e s . T h i s b e h a v i o u r i s c o n s i d e r e d t o be r e l a t e d t o v o l a t i l e p h a s e i m m i s c i b i l i t y . T h ose e l e m e n t s t h a t a r e p a r t i t i o n e d p r e f e r e n t i a l l y i n t o an a q u e o u s phase w o u l d have l o w D v a l u e s i n s o l i d s . D v a l u e s i n t h e G u i c h o n G r e e k b a t h o l i t h r o c k s s u g g e s t t h a t c o p p e r i s t h e e l e m e n t most p r e f e r e n t i a l l y p a r t i t i o n e d i n t o c h l o r i d e r i c h s o l u t i o n s e v o l v e d f r o m t h e c r y s t a l l i z i n g magma. R e s u l t s f r o m Duncan's m u l t i p l e r a n g e t e s t a l s o s u g g e s t t h a t t h e r e were two m a j o r c o n t r o l s i n t h e d i s t r i b u t i o n o f C r , Co, N i , Cu, and Zn d u r i n g t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h . T h i s s t a t i s t i c a l t e s t i n d i c a t e s t h a t N i , Co and Cr were c o n t r o l l e d by m a g m a - m i n e r a l i n t e r a c t i o n d u r i n g t h e c r y s t a l l i z a t i o n o f t h e b a t h o l i t h w h i l e Cu i n d i c a t e s a p a t t e r n a t t r i b u t e d t o m i n e r a l - v o l a t i l e p h a s e i n t e r a c t i o n . T h e e f f e c t s o f v o l a t i l e p h a s e i m m i s c i b i l i t y on t h e d i s t r i b u t i o n o f t h e s e e l e m e n t s i s q u a n t i f i e d by c o r r e l a t i o n c o e f f i c i e n t s , w h i c h a r e h i g h i n o l d e r u n i t s and l o w and i r r e g u l a r i n y o u n g e r p h a s e s . 90 INTRODUCTION The e l e m e n t s Cu, Co, N i , Cr and Zn a r e p a r t o f t h e f i r s t t r a n s i t i o n m e t a l g r o u p . T r a n s i t i o n e l e m e n t s a r e e l e m e n t s w i t h i n c o m p l e t e l y f i l l e d " d " a n d / o r " f " o r b i t a l s . F i r s t t r a n s i t i o n e l e m e n t s a r e t h e r e f o r e t h o s e e l e m e n t s w i t h i n c o m p l e t e l y f i l l e d " 3 d " o r b i t a l s . I n g e n e r a l t h e " d " s u b - s h e l l c o n s i s t s o f f i v e d e g e n e r a t e o r b i t a l s , w h i c h h o l d a maximum o f 10 e l e c t r o n s . S i n c e e a c h e l e c t r o n i n a s h e l l d e t e r m i n e s t h e p o s i t i o n o f an e l e m e n t i n t h e p e r i o d i c t a b l e , t h e f i v e " 3 d " o r b i t a l s i n d i c a t e s t h a t t h e r e a r e 10 e l e m e n t s o f t h e f i r s t t r a n s i t i o n m e t a l s e r i e s whose c h e m i s t r y i s c o n t r o l l e d by " 3 d " o r b i t a l b o n d i n g . T h i s s t u d y d e a l s m a i n l y w i t h t h e d i s t r i b u t i o n o f f i r s t t r a n s i t i o n m e t a l s e r i e s d u r i n g t h e c r y s t a l l i z a t i o n o f t h e c a l c - a l k a l i n e G u i c h o n C r e e k b a t h o l i t h magma. The " d " o r b i t a l s c o n s i s t o f t h e wave f u n c t i o n s o r i e n t a t e d i n d i f f e r e n t d i r e c t i o n s i n s p a c e b e t w e e n c a r t e s i a n c o o r d i n a t e s x, y and z. T h r e e of t h e " d " o r b i t a l s have t h e i r l o b e s b e t w e e n a x e s P x , Py and P z , and t h e s e a r e d e s i g n a t e d d X y , d y Z and d x z . The o t h e r two have t h e i r l o b e s d i r e c t e d a l o n g t h e same a x e s as t h e p' o r b i t a l s , and t h e s e a r e d e s i g n a t e d d x 2 - y 2 and d z 2 . ( G e o r g e and M c C l u r e , 1959: S h a r p e , 1 9 8 1 ) . I f n e g a t i v e l y c h a r g e d i o n s o r l i g a n d s a r e b r o u g h t t o w a r d s t h e t r a n s i t i o n m e t a l i o n an e l e c t r o s t a t i c f i e l d w i l l be c r e a t e d ( D u n i t z e t a l , 1 9 5 7 ) . I n s u c h a f i e l d t h e 3d o r b i t a l s 91 a r e n a l o n g e r d e g e n e r a t e , t h e y s p l i t up i n t o two g r o u p s o f d i f f e r e n t e n e r g i e s . The, manner o f s p l i t t i n g and t h e m a g n i t u d e o f e n e r g y d i f f e r e n c e s i s a f u n c t i o n o f wave g e o m e t r i e s and n a t u r e o f l i g a n d s . I f t h e t r a n s i t i o n m e t a l i o n i s s u r r o u n d e d o c t a h e d r a l l y by s i x l i g a n d s p l a c e d on x, y and z a x e s , t h e s p l i t t i n g o f t h e " d " o r b i t a l s w i l l be s u c h t h a t t h e o r b i t a l s d x 2 - y 2 and d z 2 a r e r a i s e d i n e n e r g y r e l a t i v e t o t h e o t h e r t h r e e s i n c e t h e s e o r b i t a l s l i e d i r e c t l y i n t h e p a t h o f a p p r o a c h i n g n e g a t i v e l y c h a r g e d i o n s ; h e n c e , e l e c t r o n -e l e c t r o n r e p u l s i o n w i l l be g r e a t e r i n t h e s e d i r e c t i o n s . I n o c t a h e d r a l e n v i r o n m e n t s , t h e t h r e e l o w e r e n e r g y o r b i t a l s d x y , d x z and dyz f o r m a g r o u p d e s i g n a t e d t g s u b g r o u p , w h i l e d x 2 - y 2 and d z 2 f o r m a h i g h e r e n e r g y eg s u b g r o u p ( F i g . 5 - 1 ) . However, i n t e t r a h e d r a l c o o r d i n a t i o n t h i s s i t u a t i o n i s r e v e r s e d t h e eg s u b g r o u p i s s t a b i l i z e d r e l a t i v e t o t h e t g s u b g r o u p ( D u n i t z e t a l 1957: G e o r g e e t a l , 1959, B u r n s e t a l , 1 9 6 4 ) . I f t h e f i e l d c r e a t e d by l i g a n d s were s p h e r i c a l l y d i s t r i b u t e d , t h e e n e r g i e s o f a l l t h e " d " o r b i t a l s w o u l d be e q u a l , j u s t as t h e y a r e i n an i s o l a t e d m e t a l i o n . I n o c t a h e d r a l c o o r d i n a t i o n , t h e f i e l d c r e a t e d by t h e s i x l i g a n d s i s n o t s p h e r i c a l l y d i s t r i b u t e d b u t c o n c e n t r a t e d a t t h e s i x c o r n e r s o f a r e g u l a r o c t a h e d r o n . The t o t a l e n e r g y o f " d " o r b i t a l s i s t h e r e f o r e u n c h a n g e d r e l a t i v e t o t h e i r s p h e r i c a l f i e l d ; h e n c e t h e c o m b i n e d e n e r g i e s o f l o w e r i n g t h e t h r e e " t g " o r b i t a l s must be e q u a l t o t h a t o f r a i s i n g t h e two " e g " o r b i t a l s ( S h a r p e , 1 9 8 1 ) . The e n e r g y o f s e p a r a t i o n o f t h e two o r b i t a l s u b s e t s i s c a l l e d c r y s t a l f i e l d s t a b i l i z a t i o n e n e r g y ( C F S E ) and d e s i g n a t e d £\ o f o r o c t a h e d r a l c o o r d i n a t i o n and t f o r t e t r a h e d r a l c o o r d i n a t i o n . The r a t i o 92 'xy d x i d y z <l x2 _ y 2 d 2 2 S Free Ion \ 3 A d „ 2 _ y 2 'In octahedral coordination" •xy 1 xy d y z d x a - y2 d z 2 \ Free Ion 14, u x y 4 d " d y z ,f f d z 8 4, d x 2 _ y 2 e. "In tetrahedral coordination* Figure.5-1: T r a n s i t i o n metals have f i v e "3d" degenerate o r b i t a l s i n a f r e e i o n , which s p l i t up i n t o two energy l e v e l s eg and t g subgroups i n octahedral and t e t r a h e d r a l c o o r d i n a t i o n s . o f t h e e n e r g y o f l o w e r i n g t h e " t g " o r b i t a l s u b g r o u p t o t h a t o f r a i s i n g t h e " e g " s u b g r o u p i s 2:3 ( G e o r g e e t a l , 1 9 5 9 ) . C r y s t a l f i e l d s t a b i l i z a t i o n e n e r g y ( C F S E ) f o r an e l e c t r o n i c c o n f i g u r a t i o n s u c h as ( t g ) m ( e g ) n , where "m" and " n " a r e t h e numbers o f e l e c t r o n s i n t h e " t g " and " e g " o r b i t a l s u b - g r o u p s r e s p e c t i v e l y , i s g i v e n by t h e r e l a t i o n Z ^ o ( 4 n - 6 m ) / i o ( D u n i t z e t a l . , 1 9 5 9 ) . I n t e t r a h e d r a l c o o r d i n a t i o n j CFSE i s g i v e n by ( 6 m - 4 n ) / 1 0 At. The d i f f e r e n c e b e t w e e n t h e two e n e r g i e s g i v e s t h e s i t e p r e f e r e n c e e n e r g y ( B u r n s and F y f e , 1 9 6 4 ) , w h i c h i s t h e e n e r g y by w h i c h a p a r t i c u l a r t r a n s i t i o n m e t a l i o n p r e f e r s e i t h e r t h e o c t a h e d r a l o r t e t r e h e d r a l s i t e d e p e n d i n g on t h e m a g n i t u d e and s i g n o f t h e d i f f e r e n c e i n e n e r g y . The m a g n i t u d e of CFSE, t h e r e f o r e d e pends on t h e number of e l e c t r o n s i n t h e " d " s u b s h e l l , and t h e manner by w h i c h s u c h e l e c t r o n s a r e f i l l e d i n t h e s e o r b i t a l s , I n a f r e e i o n , t h e f i l l i n g o f e l e c t r o n i c o r b i t a l s f o l l o w s Hund's r u l e o f maximum m u l t i p l i c i t y , i n w h i c h e l e c t r o n s a r e d i s t r i b u t e d i n s u c h a way as t o g i v e t h e maximum number o f " u n p a i r e d " e l e c t r o n s . However, i n an e l e c t r o s t a t i c f i e l d , t h e " d " o r b i t a l s a r e no l o n g e r d e g e n e r a t e , h e n c e f o r Hund's r u l e t o a p p l y t h e e n e r g y o f p a i r i n g e l e c t r o n s i n l o w e r e n e r g y o r b i t a l s s h o u l d be h i g h e r t h a n e n e r g y o f s e p e r a t i o n o f t h e two o r b i t a l s u b g r o u p s ( C F S E ) . O t h e r w i s e p a i r i n g may t a k e p l a c e b e f o r e f i l l i n g i n of t h e h i g h e r e n e r g y " t g " s u b g r o u p ( D u n i t z e t a l , 1959; G e o r g e e t a l , 1 9 5 7 ) . I n weak e l e c t r o s t a t i c f i e l d s , common i n s i l i c a t e s y s t e m s ( B u r n s e t a l , 1 9 6 4 ) , CFSE i s l o w e r t h a n e l e c t r o n r e p u l s i o n e n e r g y t h a t r e s u l t s f r o m p a i r i n g e l e c t r o n s 94 i n an o r b i t a l ( C u r t i s , 1 9 6 4 ) , h e n c e Hund's r u l e i s o b e y e d . T a b l e 5-1 s u m m a r i z e s CFSE f o r a l l t h e f i r s t t r a n s i t i o n s e r i e s m e t a l s . From t h e ab o v e d i s c u s s i o n i t i s c l e a r t h a t t h e f i r s t t r a n s i t i o n m e t a l s e x h i b i t r e g u l a r i t y and c l o s e s i m i l a r i t y i n g e n e r a l c h e m i s t r y c o n t r o l l e d by t h e n a t u r e o f " d " o r b i t a l b o n d i n g , w h i c h i s more c o m p l e x t h a n s i m p l e i o n i c b o n d i n g t h a t f o r m s t h e b a s i s f o r G o l d s c h m i d t 1 s e l e m e n t d i s t r i b u t i o n l a w s ( G o l d s c h m i d t , 1 9 3 7 ) . T h e r e f o r e t h e f i r s t t r a n s i t i o n m e t a l s a r e e x c e p t i o n s as a g r o u p t o G o l d s c h m i d t * s l a w s ( W i l l i a m s , 1959; B u r n s and F y f e , 1964; C u r t i s , 1 9 6 4 ) . The e l e m e n t s b e i n g c o n s i d e r e d i n t h i s s t u d y o c c u r i n s i l i c a t e s y s t e m s i n v a l e n c e s t a t e s C r 3 + , N i 2 + , C u 2 + and Z n 2 + w i t h 3, 7, 8, 9 and 10 " d " e l e c t r o n s r e s p e c t i v e l y . C o n s i d e r a t i o n o f CFSE and s i t e p r e f e r e n c e e n e r g i e s s u g g e s t t h a t t h e s e e l e m e n t s w i l l be p r e f e r e n t i a l l y i n c o r p o r a t e d i n o c t a h e d r a l s i t e s r e l a t i v e t o t e t r a h e d r a l s i t e s , i n . t h e o r d e r C r 3 + , N i 2 + , C u 2 + , and C o 2 + w h e r e a s Z n 2 + w i l l be e n r i c h e d i n o c t a h e d r a l n o r n e i t h e r t e t r a h e d r a l s i t e s b e c a u s e o f i t s z e r o CFSE ( C u r t i s , 1 9 6 4 ) . However, t h e t h e o r e t i c a l l y p r e d i c t e d o r d e r i s n o t a c t u a l l y f o l l o w e d i n n a t u r e ( F i g . 5 - 2 ) . F i g u r e . 5 - 2 d e r i v e d f r o m d i s t r i b u t i o n o f f i r s t t r a n s i t i o n m e t a l s i n t h e l o w e r p a r t o f t h e S k a e r g a a r d I n t r u s i o n shows t h a t c o p p e r as ( C u 2 + ) a c t u a l l y i n c r e a s e s w i t h i n c r e a s i n g d i f f e r e n t i a t i o n r a t h e r t h a n d e c r e a s i n g as p r e d i c t e d by CFSE ( C u r t i s , 1 9 6 4 ) . However, t h i s a n o m a l o u s b e h a v i o u r o f c o p p e r c a n be a l s o e x p l a i n e d i n t e r m s o f c r y s t a l f i e l d t h e o r y . C u 2 + has 9 " 3 d " 9 5 T A B L E 5-1 R E L A T I V E S T A B I L I Z A T I O N ENERGIES IN OCTAHEDRAL AND TETRAHEDRAL F I E L D S . F I L L I N G OF AN ELECTRON IN " t g " ORBITAL IN OCTAHEDRAL COORDINATION LOWERS ENERGY BY 2/5Ao WHILE PUTTING AN ELECTRON INTO ' e g ' SUBGROUP RAISES ENERGY BY 3/5A„ T r a n s i t i o n N o . o f C F S E i n C F S E i n m e t a l i o n d - e l e c t r o n s O c t a h e d r a l ( 4 o / 1 0 ) t e t r a h e d r a l ( 4 t / 1 0 ) S c 3 + 0 0 0 T i 3 + 1 4 6 V 3 + 2 8 12 C r 3 + 3 12 8 Mn3+ 4 6 4 F e 3 + 5 0 0 F e 2 + 6 4 6 C o 2 + 7 8 12 N i 2 + 8 12 8 C u 2 + 9 6 4 Z n 2 + 10 0 0 3 0 0 E a a a c o O c CD E a> in 2 0 0 -1 0 0 -Figure.5-2: Distribution of transition metals during c r y s t a l l i z a t i o n of Skaergaard basic intrusion, showing that Cr, Ni, and V decreases rapidly with progressive d i f f e r e n t i a t i o n , whereas Cu increases. (A = Olivine Gabbro; B =Hyperthene-01ivine Gabbro; C = Olivines - free Grabbro; D = Hortonolite Ferrogabbro Fayalite Ferrogabbro) (modified from Curtis,1964). Ov 9 7 o r b i t a l s w i t h one o f t h e " e g " o r b i t a l s u b g r o u p f o r m i n g t h e v a l e n c e o r b i t a l s . U n l i k e t h e t h r e e t g o r b i t a l s u b g r o u p t h e two o r b i t a l s u b g r o u p a r e s l i g h t l y d i f f e r e n t . H e n c e , t h e g r o u n d s t a t e of C u 2 + may e i t h e r be ( d z 2 ) 1 ( d x 2 - y 2 ) 2 o r ( d x 2 - y 2 ) 1 ( d z 2 ) 2 where s u p e r s c r i p t s i n d i c a t e number o f e l e c t r o n s i n an o r b i t a l . T h e r e f o r e t h i s shows t h a t i n t h e f i r s t c a s e t h e r e a r e two e l e c t r o n s c o n c e n t r a t e d b e t w e e n xy a x e s and one a l o n g t h e z - a x i s , w h i l e i n t h e s e c o n d c a s e t h e r e v e r s e i s t r u e . I n an e l e c t r o s t a t i c f i e l d t h e r e f o r e l i g a n d s o f t h e f i r s t c a s e w i l l be s c r e e n e d by a p p a r e n t l y h i g h e r c h a r g e a l o n g xy a x i s t h a n a l o n g z - a x i s . T h e r e f o r e , t h e r e s u l t o f t h i s i s r e - a r r a n g e m e n t o f o r b i t a l g e o m e t r y t o f i n d a s t a b l e p o s i t i o n , h e n c e by so d o i n g d i s t o r t i n g o r i g i n a l o r b i t a l g e o m e t r y ( C u r t i s , 1 9 6 4 ) . The C u 2 + s t r u c t u r e i s t h e r f o r e r e f e r r e d t o as d e s t a b i l i z e d i n o c t a h e d r a l c o o r d i n a t i o n . S i l i c a t e m e l t s and s o l i d s d e r i v e d f r o m them c o n s i s t s t r u c t u r a l l y o f compounds i n w h i c h o c t a h e d r a l and t e t r a h e d r a l c o o r d i n a t i o n a r e d o m i n a n t ( B u r n s and F y f e , 1 9 6 4 ) . I n g e n e r a l , t h e s e s t r u c t u r a l s i t e s i n s o l i d s c a n be r e f e r r e d t o as r e g u l a r w h e r e a s i n m e l t s b e c a u s e o f t h e i r l i q u i d n a t u r e t h e y w i l l be s l i g h t l y d i s t o r t e d . D u r i n g d i f f e r e n t i a t i o n o f a magma, compounds i n w h i c h o c t a h e d r a l s i t e s a r e d o m i n a n t s u c h as o l i v i n e s and p y r o x e n e s a r e p r e f e r e n t i a l l y c r y s t a l l i z e d f i r s t r e l a t i v e t o t h o s e t e t r a h e d r a l i n n a t u r e l i k e f e l d s p a r s . Those e l e m e n t s t h a t p r e f e r r e g u l a r o c t a h e d r a l s i t e s s u c h as N i 2 + , C o 2+ and C r 3 + w i l l be p r e f e r e n t i a l l y d e p l e t e d f r o m t h e magma a t t h e e a r l y s t a g e s , w h e r e a s t h o s e w h i c h p r e f e r d i s t o r t e d s i t e s 98 s u c h a s Cu 2+ w i l l , b e s l i g h t l y c o n c e n t r a t e d i n magma r e l a t i v e t o s o l i d s ( F i g . 5 - 2 ) . F e i s s ( 1 9 7 8 ) a l s o t r i e d t o e x p l o i t c r y s t a l f i e l d t h e o r y i n h i s a t t e m p t t o d i s c r i m i n a t e b e t w e e n m i n e r a l i z e d and u n m i n e r a l i z e d ' p l u t o n s . He u s e d t h e r a t i o A l 2 0 3 / ( K 2 0 + CaO + Na20) as a r e l a t i v e m easure o f o c t a h e d r a l s i t e s t h a t e x i s t e d i n t h e magma, s i n c e e x c e s s a l u m i n u m o v e r t h e sum o f a l k a l i s i s a s s o c i a t e d w i t h f e r r o m a g n e s i a n m i n e r a l s i n w h i c h A l 3 + o c c u p y o c t a h e d r a l s i t e s . He a r g u e d t h a t t h e l a r g e r t h e r a t i o t h e h i g h e r t h e o c t a h e d r a l s i t e s i n magma, h e n c e t h e h i g h e r t h e c a p a b i l i t y o f s u c h a magma t o t r a n s p o r t t r a n s i t i o n m e t a l s t o a p i c a l z o n e s where t h e y w i l l be p a r t i t i o n e d t o h y d r o t h e r m a l f l u i d s . H owever, F e i s s ' s s t u d y d i d n o t t a k e i n t o a c c o u n t t h a t t h e a bove r a t i o and henc e r e l a t i v e number o f o c t a h e d r a l s i t e s i s a f u n c t i o n o f d e g r e e o f d i f f e r e n t i a t i o n o f t h e magma. C r y s t a l s i n w h i c h o c t a h e d r a l s i t e s a r e d o m i n a n t a r e i n a c t u a l f a c t removed e a r l y d u r i n g c r y s t a l l i z a t i o n h i s t o r y o f s i l i c a t e magma, t h u s d e p l e t i n g t r a n s i t i o n m e t a l s f r o m r e s i d u a l magma i n s t e a d e n r i c h i n g them. I n t h i s s t u d y , d i s t r i b u t i o n o f Co, Cu, N i , Cr and Zn d u r i n g t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h w i l l be e v a l u a t e d , and a l s o an a t t e m p t w i l l be made t o a s s e s s t h e p o s s i b i l i t y o f u s i n g t h e r e s u l t i n g d i s t r i b u t i o n p a t t e r n s i n o r e p o t e n t i a l a n a l y s i s o f g r a n i t o i d p l u t o n s . VARIATION OF TRACE ELEMENTS DURING MAGMATIC CRYSTALLIZATION The r e l a t i v e e n r i c h m e n t o f t r a c e e l e m e n t s b e t w e e n 99 c r y s t a l l i z i n g s o l i d s and c o e x i s t i n g s i l i c a t e m e l t s u n d e r assumed e q u i l i b i u m i s c o n s i d e r e d i n t e r m s o f two e x t r e m e m o d e l s . 1) R a y l e i g h f r a c t i o n a l c r y s t a l l i z a t i o n m o d e l . I n t h i s model w h i c h i s o f t e n r e f e r r e d t o as a p e r f e c t f r a c t i o n a l c r y s t a l l i z a t i o n , m o d e l , i t i s assumed t h a t c r y s t a l s s e p a r a t e f r o m m e l t as s o o n as t h e y a r e f o r m e d , e i t h e r t h r o u g h g r a v i t a t i o n a l s e t t l i n g as a r e s u l t o f m e l t r e m o v a l t h r o u g h f i l t e r p r e s s i n g . T h e model i s d e s c r i b e d by t h e r e l a t i o n C l / C o = F 1 1 - 1 where CI = c o n c e n t r a t i o n o f e l e m e n t i n r e s i d u a l m e l t . Co = i n i t i a l c o n c e n t r a t i o n o f e l e m e n t i n m e l t . F = f r a c t i o n o f m e l t r e m a i n i n g . D = X i K d = b u l k d i s t r i b u t i o n c o e f -f i c i e n t where X i = f r a c t i o n of m i n e r a l i i n c r y s t a l l i z i n g s o l i d and Kd = m i n -e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t of a p a r t i c u l a r e l e m e n t . 2) S u r f a c e e q u i l i b r i u m m o d e l . Here c r y s t a l s u r f a c e s a r e assumed t o i n t e r a c t w i t h c o e x i s t i n g m e l t . The model i s d e s c r i b e d by t h e r e l a t i o n C l / C o = 1/(F + D ( l - F ) ) where a l l s y m b o l s a r e as b e f o r e . 100 DISTRIBUTION COEFFICIENTS The e l e m e n t s Cu, Co, C r , N i , and Zn o c c u r i n m e a s u r a b l e amounts i n b a s i c and u l t r a b a s i c r o c k s , i n a c c o r d a n c e w i t h t h e i r p r e f e r e n c e f o r o c t a h e d r a l s i t e s , w h i c h a r e a b u n d a n t i n f e r r o m a g n e s i a n m i n e r a l s , s u c h as o l i v i n e s and p y r o x e n e s . H e nce, many s t u d i e s o f d i s t r i b u t i o n o f t h e s e e l e m e n t s d u r i n g m a g m a t i c d i f f e r e n t i a t i o n h ave been c o n f i n e d m a i n l y t o b a s i c r o c k s ( P h i l p o t t s e t a l . , 1970; Wager e t a l . , 1 9 5 1 ) . S i m i l a r s t u d i e s i n i n t e r m e d i a t e and g r a n i t i c r o c k s a r e r a r e , h e n c e d i s t r i b u t i o n c o e f f i c i e n t s o f t h e s e e l e m e n t s i n t h e s e g r o u p s o f r o c k s a r e n o t r e a d i l y a v a i l a b l e i n t h e l i t e r a t u r e . B e c a u s e o f t h e u n a v a i l a b i l i t y o f m i n e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t s o f t h e above m e t a l s , b u l k d i s t r i b u t i o n c o e f f i c i e n t s f o r G u i c h o n b a t h o l i t h r o c k s were c a l c u l a t e d f r o m i n v e r s e r e l a t i o n s . A s s u m i n g a c l o s e s y s t e m , mass b a l a n c e c a l c u l a t i o n s show t h a t c o n c e n t r a t i o n o f any t r a c e e l e m e n t i n c r y s t a l l i z i n g s o l i d s and c o e x i s t i n g m e l t i s g i v e n by t h e e q u a t i o n Co = C1F + (1 - F ) C s where Cs = c o n c e n t r a t i o n o f e l e m e n t i n b u l k s o l i d and o t h e r s y m b o l s a r e as d e s c r i b e d p r e v i o u s l y . R e - a r r a n g e m e n t o f t h e above e q u a t i o n g i v e s CI = <Co - ( l - F ) C s > / F S i n c e i n t h e a b o v e e q u a t i o n i f Co, Cs and F a r e known, ( C I ) c o n c e n t r a t i o n o f t r a c e e l e m e n t i n r e s i d u a l m e l t c a n be c a l c u l a t e d . The b u l k r o c k t r a c e e l e m e n t c o m p o s i t i o n s o f t h e G u i c h o n 101 C r e e k b a t h o l i t h p h a s e s s u m m a r i z e d as a r i t h m e t i c mean v a l u e s f o r e a c h p h a s e a r e l i s t e d i n T a b l e 5 - 2 ( a ) and c a l c u l a t e d m e l t c o m p o s i t i o n s a r e l i s t e d i n T a b l e 5 - 2 ( b ) . The i n i t i a l c o m p o s i t i o n o f t h e magma was c a l c u l a t e d as a w e i g h t e d a v e r a g e , as f o l l o w s : 99 ppm Cu, 14 ppm N i , 14 ppm Co, 22 ppm Cr and 57 ppm Z n. As d i s c u s s e d i n an e a r l i e r c h a p t e r t h e d e g r e e o f c r y s t a l l i z a t i o n o f t h e G u i c h o n magma may be a p p r o x i m a t e d f r o m p e r c e n t a r e a o f e x p o s u r e o f e a c h p h a s e . T h e r e f o r e " F " c a n be a p p r o x i m a t e d f r o m t h i s r e l a t i o n s h i p . S i n c e Co, C s , and F a r e known t h e c a l c u l a t i o n o f CI f r o m t h e above e q u a t i o n was a s t e p w i s e c a l c u l a t i o n . T h a t i s , t h e c o n c e n t r a t i o n ( C I ) of t h e m e l t t h a t c o e x i s t e d w i t h B o r d e r p h a s e was done u s i n g i n i t i a l c o n c e n t r a t i o n o f t h e p a r e n t magma. However, c a l c u l a t i o n o f m e l t t h a t c o e x i s t e d w i t h G u i c h o n v a r i e t y was done u s i n g t h e c o n c e n t r a t i o n o f m e l t t h a t c o e x i s t e d w i t h B o r d e r p h a s e as p a r e n t l i q u i d t o G u i c h o n v a r i e t y . S u b s e q u e n t c a l c u l a t i o n s f o r y o u n g e r phase f o l l o w e d t h e same s e q u e n c e , t h a t i s , u s i n g t h e c o n c e n t r a t i o n o f l i q u i d t h a t c o - e x i s t e d w i t h t h e r o c k phase i m m e d i a t e l y o l d e r t h a n t h e r o c k p h a s e b e i n g c o n s i d e r e d . The c o n c e n t r a t i o n o f an e l e m e n t b etween two c h e m i c a l p h a s e s i n e q u i l i b r i u m i s g i v e n by t h e N e r s t d i s t r i b u t i o n c o e f f i c i e n t : D = c o n c e n t r a t i o n o f e l e m e n t i i n pha s e A c o n c e n t r a t i o n o f e l e m e n t i i n p h a s e B I n o ur c a s e t h e b u l k d i s t r i b u t i o n c o e f f i c e n t D i s g i v e n by D = C o n c e n t r a t i o n o f e l e m e n t i i n s o l i d p h a s e ( C s ) C o n c e n t r a t i o n e l e m e n t i i n c o e x i s t i n g l i q u i d C I TABLE 5 - 2 ( a ) AVERAGE TRACE ELEMENT COMPOSITION OF GUICHON CREEK BATHOLITH PHASES Co Cr Cu N i Pb Zn B o r d e r P h a s e 19 ppm 35 ppm 123 ppm 21 ppm 6 ppm 76 ppm G u i c h o n V a r i e t y 16 ppm 28 ppm 109 ppm 18 ppm 9 ppm 51 ppm Chataway V a r i e t y 9 ppm 9 ppm 103 ppm 9 ppm 4 ppm 40 ppm B e t h l e h e m P h a s e 8 ppm 8 ppm 53 ppm 5 ppm 7 ppm 54 ppm B e t h s a i d a Phase 7 ppm 5 ppm 48 ppm 4 ppm 7 ppm 42 ppm TABLE 5 - 2 ( b ) RESIDUAL MELT TRACE ELEMENT CONCENTRATION VARIATION DURING THE CRYSTALLIZATION THE GUICHON BATHOLITH MAGMA CALCULATED FOR MAGMA THAT COEXISTED WITH BORDER PHASE, GUICHON VARIETY, CHATAWAY VARIETY AND BETHLEHEM PHASE. Co(ppm) Cr(ppm) Cu(ppm) N i ( p p m ) Pb(ppm) Zn(ppm) B o r d e r P h a s e 12 16 87 11 9 48 G u i c h o n V a r i e t y 9 8 72 6 9 46 Chataway V a r i e t y 9 7 51 4 12 50 B e t h l e h e m Phase 10 9 54 4 11 58 o NJ TABLE 5-3 BULK DISTRIBUTION COEFFICIENTS FOR GUICHON BATHOLITH ROCKS CALCULATED FROM THE RELATION D = C s / C l WHERE Cs = BULK SOLID TRACE ELEMENT OF EACH PHASE AND C I = TRACE ELEMENT CONCENTRATION THAT COEXISTED WITH CRYSTALLIZING SOLID. »Co DCr DCu DNi Dpb DZn B o r d e r P h a s e 1.58 2.19 1.41 1.91 0.67 1.58 G u i c h o n V a r i e t y 1.78 3.50 1.51 3.00 1.00 1.11 Chataway V a r i e t y 1.00 1.29 2.02 2.25 0.33 0.80 'Bethlehem V a r i e t y 1.13 0.56 0.98 1.00 0.64 0.72 D i s t r i b u t i o n c o e f f i c i e n t s c a l c u l a t e d f r o m t h e a b o v e r e l a t i o n s a r e l i s t e d i n T a b l e 5-3. T h e o r e t i c a l l y t h e c a l c u l a t e d b u l k d i s t r i b u t i o n c o e f f i c i e n t s a r e d e s c r i b e d by t h e r e l a t i o n D = X i K i d where X i = f r a c t i o n o f m i n e r a l i i n t h e b u l k s o l i d . K i d = m e l t - m i n e r a l d i s t r i b u t i o n c o e f f i c i e n t o f a p a r t i c u l a r e l e m e n t f o r m i n e r a l i . D i s t r i b u t i o n c o e f f i c i e n t s c a l c u l a t e d a b o v e a r e a measure o f t h e r e l a t i v e c o n c e n t r a t i o n s o f t r a c e e l e m e n t s b e tween b u l k s o l i d and c o e x i s t i n g s i l i c a t e m e l t s and do n o t t a k e i n t o a c c o u n t t h e manner i n w h i c h s u c h s o l i d s o c c u r . Hence f r o m b u l k d i s t r i b u t i o n c o e f f i c i e n t s i t i s d i f f i c u l t t o e v a l u a t e t h e r e l a t i v e i m p o r t a n c e o f e a c h m i n e r a l i n t e r m s o f i t s t r a c e e l e m e n t c o n t e n t , and a l s o t h e i n f l u e n c e o f m e l t s f o u n d i n t e r s t i t i a l t o m i n e r a l c r y s t a l s . B u t e v e n w i t h t h e s e l i m i t a t i o n s t h e a u t h o r c o n s i d e r s t h e b u l k d i s t r i b u t i o n a r e l i a b l e m e a sure o f t r a c e e l e m e n t d i s t r i b u t i o n i n c r y s t a l l i z i n g s o l i d s and c o e x i s t i n g m e l t s i n p l u t o n i c e n v i r o n m e n t s . U n l i k e v o l c a n i c e n v i r o n m e n t , r a t e o f c r y s t a l l i z a t i o n i n s l o w e r , l i q u i d i s t r a p p e d b e t w e e n c r y s t a l s , and b e c a u s e o f r a t e o f c r y s t a l l i z a t i o n i n t e r s t i a l m e l t may c r y s t a l l i z e i n t o c r y s t a l s w h i c h may be d i f f i c u l t t o d i s t i n g u i s h f r o m e a r l y f o r m e d c r y s t a l s . A n o t h e r p r o b l e m i s t h a t a v o l c a n i c r o c k m a t r i x w h i c h a p p r o x i m a t e s c o e x i s t i n g m e l t i s n o t r e a d i l y a p p a r e n t i n a p l u t o n i c e n v i r o n m e n t . Hence i n p l u t o n i c s y s t e m s m i n e r a l - m e l t d i s t r i b u t i o n c o e f f i c i e n t c a n n o t g i v e r e l i a b l e i n f o r m a t i o n a b o u t 105 d i s t r i b u t i o n o f t r a c e e l e m e n t s ; b u t b u l k d i s t r i b u t i o n s c o e f f i c i e n t s a r e much more r e l i a b l e t h a n m e l t - m i n e r a l d i s t r i b u t i o n c o e f f i c i e n t s . T a b l e 5-3, t h e r e f o r e s u m m a r i z e s b u l k d i s t r i b u t i o n c o e f f i c i e n t s f o r t h e e l e m e n t s u n d e r c o n s i d e r a t i o n . From T a b l e 5-3, i t i s a p p a r e n t t h a t f o r t h e g r e a t e r p a r t of c r y s t a l l i z a t i o n t h e b u l k d i s t r i b u t i o n c o e f f i c i e n t s were more t h a n one w h i c h i s i n a g r e e m e n t w i t h t h e f o r g o i n g d i s c u s s i o n s and t h e r e l a t i v e p r e f e r e n c e o f t h e s e e l e m e n t s f o r e a r l y d i f f e r e n t i a t i n g s o l i d s . T h e o r e t i c a l l y , t h e c o n c e n t r a t i o n s o f t h e s e e l e m e n t s i n c r y s t a l l i z i n g s o l i d s s h o u l d d e c r e a s e as f e r r o m a g n e s i a n m i n e r a l s d e c r e a s e , h e n c e b u l k d i s t r i b u t i o n c o e f f i c i e n t s s h o u l d d e c r e a s e w i t h i n c r e a s i n g d i f f e r e n t i a t i o n o f t h e magma. T a b l e 5-3 shows t h a t d i s t r i b u t i o n c o e f f i c i e n t s a r e l o w e r i n t h e B o r d e r p h a s e t h a n i n G u i c h o n v a r i e t y c o n t r a r y t o e x p e c t a t i o n s . However, t h i s i s t h o u g h t t o be r e l a t e d t o t h e f a c t t h a t B o r d e r p h a s e r e p r e s e n t s a r e l a t i v e l y f i n e g r a i n e d u n i t o f t h e b a t h o l i t h i n w h i c h c r y s t a l l i z a t i o n was r a t h e r f a s t e r , and hence t r a c e e l e m e n t s a c c u m u l a t i o n was n o t , as i n o t h e r p h a s e s f o r m e d u n d e r c o n d i t i o n s o f s l o w e r c r y s t a l l i z a t i o n . H owever, f r o m G u i c h o n v a r i e t y t o y o u n g e r p h a s e s t h e d i s t r i b u t i o n c o e f f i c i e n t s d e c r e a s e as t h e o r y a n t i c i p a t e s . The o t h e r i m p o r t a n t f a c t shown i n T a b l e 5-3, i s t h a t C r , N i and Co have h i g h e r d i s t r i b u t i o n c o e f f i c i e n t s i n t h a t o r d e r , w h i c h i s t h e o r d e r p r e d i c t e d by CFSE. I n o t h e r w o r d s , t h i s c l e a r l y c o n f i r m s t h e f a c t t h a t t h e s e e l e m e n t s were p r e f e r e n t i a l l y i n c o r p o r a t e d i n o c t a h e d r a l s i t e s d u r i n g c r y s t l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h and 106 a l s o t h a t m i n e r a l d i f f e r e n t i a t i o n a c c o u n t s f o r t r a c e e l e m e n t c o m p o s i t i o n o f t h e b a t h o l i t h i c p h a s e s . T a b l e 5-3 a l s o shows t h a t d i s t r i b u t i o n c o e f f i c i e n t s s u g g e s t t h a t r e l a t i v e t o N i , Co, and C r , Cu i n c r e a s e s w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n u n t i l a f t e r c r y s t a l l i z a t i o n o f Chataway v a r i e t y , a f t e r w h i c h i t d e c r e a s e s . T h i s o r d e r f o r c o p p e r d i s t r i b u t i o n i s a l s o c o n s i s t e n t w i t h t h e o r d e r p r e d i c t e d by c r y s t a l f i e l d t h e o r y , as Cu 2+ i o n i n d e s t a b i l i z e d o c t a h e d r a l s i t e s . The c r y s t a l l i z a t i o n o f B e t h l e h e m p h a s e i s a c c o m p a n i e d by a r a t h e r d r a m a t i c d r o p i n b u l k d i s t r i b u t i o n c o e f f i c i e n t s o f t h e s e e l e m e n t s e s p e c i a l l y Cu and C r . Though t h i s may n o t be r e a d i l y a p p a r e n t a t t h e moment e s p e c i a l l y b e c a u s e o f l a c k o f e x p e r i m e n t a l e v i d e n c e t h e a u t h o r r e l a t e s t h i s d r a m a t i c c h a n g e i n d i s t r i b u t i o n c o e f f i c i e n t s t o v o l a t i l e f l u i d i m m i s c i b i l i t y w h i c h t o g e t h e r w i t h a v a i l a b l e g e o l o g i c e v i d e n c e s u g g e s t s t h a t i t t o o k p l a c e d u r i n g c r y s t a l l i z a t i o n o f t h e c o r e o f t h e b a t h o l i t h c o n s i s i t i n g o f B e t h l e h e m and B e t h s a i d a p h a s e s . The same c o n c l u s i o n was r e a c h e d by J o h a n and M c M i l l a n , 1980 Neumann ( 1 9 4 8 ) a p p r o x i m a t e d d i s t r i b u t i o n p a t t e r n s o f t r a c e e l e m e n t s among c r y s t a l l i z i n g s o l i d , c o e x i s t i n g m e l t and s e p a r a t i n g a q u e o u s f l u i d . I n h i s a n a l y s i s he assumed t h a t p a r t i t i o n i n g o f t r a c e e l e m e n t s i n t o c r y s t a l l i z i n g s o l i d s c o e x i s t i n g w i t h h y d r o u s m e l t and a q u e o u s f l u i d c a n be c o n s i d e r e d t o be f a r l o w e r t h a n p a r t i t i o n i n g o f t h e s e e l e m e n t s b e t ween s i l i c a t e m e l t and a q u e o u s p h a s e , h e n c e e f f e c t s o f s o l i d s can be n e g l e c t e d . The p a r t i t i o n i n g o f any t r a c e e l e m e n t b e t ween m e l t and c o e x i s i t i n g a q u e o u s p h a s e w i l l be a f u n c t i o n of t h e r e l a t i v e s o l u b i l i t i e s o f t h e e l e m e n t i n t h e two p h a s e s . 107 H o l l a n d ( 1 9 7 2 ) , Burnham ( 1 9 7 9 ) and K h l t a r o v e t a l , ( 1 9 8 2 ) showed t h a t p a r t i t i o n i n g o f t r a c e e l e m e n t s t o an a q u e o u s p h a s e depends on t h e c o m p o s i t i o n o f t h a t s o l u t i o n . I n p a r t i c u l a r t h e y showed t h a t e x t r a c t i o n o f m e t a l s c o n s i d e r e d i n t h i s s t u d y f r o m a s i l i c a t e m e l t by an a q u e o u s p h a s e i s g r e a t l y e n h a n c e d by t h e p r e s e n c e o f c h l o r i n e . T h a t i s , s u c h m e t a l s a r e t r a n s p o r t e d i n a q u e o u s p h a s e as c h l o r i d e c o m p l e x e s . K h i t a r o v e t a l . , ( 1 9 8 2 ) m e a s u r e d d i s t r i b u t i o n c o e f f i c i e n t s o f C u 2 + , P b 2 + and Z n 2 + between g r a n i t i c m e l t and c h l o r i d e s o l u t i o n . They f o u n d t h a t Cu 2+ has t h e h i g h e s t p a r t i t i o n c o e f f i c i e n t o f t h e t h r e e m e t a l i o n s and was c o n c e n t r a t e d i n s o l u t i o n by a r a t i o o f 5:1. Thus r e l a t i v e s o l u b i l i t i e s o f t h e s e e l e m e n t s i n an a q u e o u s p h a s e c a n be i n f e r r e d f r o m t h e d i s t r i b u t i o n c o e f f i c i e n t s o f s o l i d s t h a t c r y s t a l l i z e d d u r i n g e v o l u t i o n o f a s e p a r a t e v o l a t i l e p h a s e . E l e m e n t s w h i c h p a r t i t i o n p r e f e r r e n t i a l l y i n t o f l u i d p h a s e w i l l have v e r y l o w d i s t r i b u t i o n c o e f f i c i e n t s b e t w e e n s o l i d s and m e l t s i n c e t h e y w i l l be r e l a t i v e l y d e p l e t e d i n t h e m e l t . From T a b l e 5-3 i t seems Cu, Cr and Zn a r e p r e f e r e n t i a l l y i n c o r p o r a t e d i n a q u e o u s phase t h a n a r e o t h e r m e t a l s i n t h i s s t u d y . ANALYSIS OF VARIANCE So f a r t h e d i s c u s s i o n s p r e s e n t e d a b o u t t h e d i s t r i b u t i o n of Cu, Co, C r , N i and Zn have been c h e m i c a l i n n a t u r e . To q u a n t i f y i n t e r p r e t a t i o n s drawn f r o m t h i s c h e m i c a l a p p r o a c h , 108 a n a l y s i s o f v a r i a n c e was c a r r i e d o u t . A n a l y s i s o f v a r i a n c e i s a s t a t i s t i c a l t e c h n i q u e s w h e r e b y t h e t o t a l v a r i a b i l i t y b etween i n d e p e n d e n t p o p u l a t i o n s c a n be s e p a r a t e d i n t o c o m p o n e n t s t o i s o l a t e s o u r c e s o f v a r i a b i l i t y . I n t h i s w o r k , t r a c e e l e m e n t d a t a f r o m t h e f i v e p h a s e s o f t h e b a t h o l i t h a r e assumed t o f o r m f i v e l o g n o r m a l l y d i s t r i b u t e d p o p u l a t i o n s w i t h means M^, Mg, MQ, Mp and Mg and common v a r i a n c e 62. The a i m o f t h e a n a l y s i s i s t h e r e f o r e t o d e t e r m i n e w h e t h e r t h e t o t a l v a r i a b i l i t y o f t h e f i v e s a m p l e s o r t r e a t m e n t s , a r e m a i n l y due t o random v a r i a n c e o r w h e t h e r s y s t e m a t i c v a r i a n c e c o n t r i b u t e s s i g n i f i c a n t l y t o t h e t o t a l v a r i a n c e . The p r o c e d u r e s e p a r a t e s t h e t o t a l v a r i a b i l i t y i n t o 1) v a r i a b i l i t y due t o s o u r c e s t h a t a r i s e m a i n l y w i t h i n s a m p l e s w h i c h i s c o n s i d e r e d t o be random v a r i a n c e o n l y ; and 2) v a r i a b i l i t y b e t w e e n s a m p l e s w h i c h measure b o t h random and s y s t e m a t i c v a r i a n c e s . F o r p u r p o s e s o f s i m p l i c a t i o n , i t i s assumed i n t h i s work t h a t random v a r i a n c e s tems m a i n l y f r o m s a m p l i n g and a n a l y t i c a l e r r o r s , s i n c e c h e m i c a l c o m p o s i t i o n a l v a r i a b i l i t y o f r o c k s w i t h i n p h a s e s a r e c o n s i d e r e d s m a l l and h ence p h a s e s c a n be assumed t o be c o m p o s i t i o n a l l y u n i f o r m . By t h i s a p p r o a c h t h e r e f o r e t h e s t a t i s t i c a l t e s t w i l l d e t e r m i n e w h e t h e r t o t a l v a r i a b i l i t y i n t r a c e e l e m e n t i n t h e f i v e p h a s e s o f t h e b a t h o l i t h i s due m a i n l y t o a n a l y t i c a l e r r o r (random v a r i a n c e ) o r c o m p o s i t i o n a l d i f f e r e n c e s between p h a s e s c o n t r i b u t e s s i g n i c f i c a n t l y t o t o t a l v a r i a b i l i t y . The a p p r o p r i a t e s t a t i s t i c a l t e s t c a r r i e d o u t i n t h i s c a s e i s t h e F 109 S o u r c e o f V a r i a t i o n T o t a l B e t w e e n P o p u l a t i o n s W i t h i n P o p u l a t i o n TABLE 5 - 4 ( a ) ANALYSIS OF VARIANCE CALCULATION PROCEDURE D e g r e e s o f Freedom N - 1 k - 1 N-k Sum o f S q u a r e s SSE=SST-SSA Mean S q u a r e S1 2=SSA k-1 S 2=SSE N-k C a l c u l a t e d f f = S i ! S2-TABLE 5 - 4 ( b ) ANALYSIS OF VARIANCE DATA FOR COBALT (DATA ARE LOG-TRANSFORMED) S o u r c e o f V a r i a t i o n B etween P o p u l a t i o n s W i t h i n P o p u l a t i o n s D e g r e e s o f Freedom 231 Sum o f S q u a r e s SSA=9.41 SSE=11.38 Mean S q u a r e S i 2 = 2 . 3 5 S 2=0.049 C a l c u l a t e d F V a l u e F = S 1 2 / S 2 =47.96 TOTAL 235 SST=20.79 F0.05 ( 4 , 2 3 1 ) = 2.37 110 TABLE 5 - 4 ( c ) S o u r c e o f V a r i a t i o n B e t w een P o p u l a t i o n s W i t h i n P o p u l a t i o n TOTAL ANALYSIS OF VARIANCE DATA FOR CHROMIUM (VALUES LOG-TRANSFORMED) D e g r e e s o f Freedom 231 235 Sum o f S q u a r e s Mean S q u a r e SSA=47.16 S i 2 = 1 1 . 7 9 SSE=34.12 S 2=0.15 SST=81.28 C a l c u l a t e d F V a l u e F = S i 2 / S 2 = 78.6 TABLE 5 - 4 ( d ) S o u r c e o f V a r i a t i o n W i t h i n P o p u l a t i o n B e t w een P o p u l a t i o n s TOTAL ANALYSIS OF VARIANCE DATA FOR COPPER (VALUES ARE LOG-TRANSFORMED) D e g r e e s o f F r e e dom 231 4 235 Sum o f S q u a r e s Mean S q u a r e SSE=52.62 S 2=0.23 SSA=13.25 S i 2 = 3 . 3 1 SST=65.87 C a l c u l a t e d F V a l u e F = S i 2 = 14.4 I l l TABLE 5 - 4 ( e ) S o u r c e s o f V a r i a t i o n B e t w e en P o p u l a t i o n W i t h i n P o p u l a t i o n T o t a l ANALYSIS OF VARIANCE DATA FOR NICKEL (VALUES LOG-TRANSFORMED) D e g r e e s o f Freedom 231 235 Sum o f S q u a r e s Mean S q u a r e SSA=29.10 S i 2 = 7 . 2 8 SSE=20.91 S 2=0.091 SST=50.01 C a l c u l a t e d F V a l u e F = S i 2 / S 2 =80 TABLE 5 - 4 ( f ) S o u r c e s o f V a r i a t i o n B etween P o p u l a t i o n W i t h i n P o p u l a t i o n T o t a l ANALYSIS OF VARIANCE DATA FOR ZINC (VALUES LOG-TRANSFORMED) D e g r e e s o f Freedom 231 235 Sum o f S q u a r e s SSA=3.86 SSE=8.55 SST=12.41 Mean S q u a r e S i 2 = 0 . 9 7 S 2=0.037 C a l c u l a t e d F V a l u e F = S ! 2 / S 2 = 26.2 112 t e s t . The t e s t was c a r r i e d o u t a t t h e 5 p e r c e n t s i g n i f i c a n t l e v e l w i t h d e g r e e s o f f r e e d o m ( 4 , 2 3 2 ) , s i n c e t h e r e a r e f i v e s a m p l e s and a t o t a l o f 237 t r a c e e l e m e n t a n a l y s e s . The F c r i t i c a l v a l u e a t t h e 5 p e r c e n t s i g n i f i c a l l e v e l and d e g r e e s o f f r e e d o m ( 4 , 232) i s 2 . 3 7 . T a b l e 5 - 4 ( a ) s u m m a r i z e s t h e a n a l y s i s o f v a r i a n c e c a l c u l a t i o n p r o c e d u r e s w h i l e t a b l e 4 ( b - f ) c o n t a i n s a n a l y s i s o f v a r i a n c e d a t a f o r C o , C r , C u , N i and Zn r e s p e c t i v e l y . I n e a c h c a s e t h e c a l c u l a t e d F v a l u e e x c e e d s t h e c r i t i c a l v a l u e , t h u s s u g g e s t i n g t h a t a t l e a s t two o f t h e mean v a l u e s o f t r a c e e l e m e n t d a t a o f t h e p h a s e s o f t h e G u i c h o n b a t h o l i t h a r e s i g n i f i c a n t l y d i f f e r e n t . H o w e v e r , t h e m o d e l u s e d d o e s n o t t e l l us w h i c h o f t h e mean v a l u e s , o r p h a s e s o f t h e G u i c h o n b a t h o l i t h a r e d i f f e r e n t , i n t r a c e e l e m e n t c o n t e n t . DUNCAN'S M U L T I P L E RANGE T E S T As d i s c u s s e d above t h e a n a l y s i s o f v a r i a n c e m o d e l u s e d does n o t t e l l w h i c h p h a s e s o f t h e b a t h o l i t h i c p h a s e s a r e d i f f e r e n t i n t r a c e e l e m e n t c o n t e n t . One o f t h e t e c h n i q u e s t h a t c a n be u s e d t o s o l v e t h i s p r o b l e m i s D u n c a n ' s m u l t i p l e r a n g e t e s t . D u n c a n ' s m u l t i p l e r a n g e t e s t p r o v i d e s a p a r a m e t e r c a l l e d t h e l e a s t s i g n i f i c a n t r a n g e (Rp) w i t h w h i c h d i f f e r e n c e s b e t w e e n s ample o r t r e a t m e n t means ( i n t h i s c a s e mean t r a c e e l e m e n t c o n t e n t i n p h a s e s o f t h e b a t h o l i t h ) can be c o m p a r e d . D i f f e r e n c e s b e t w e e n any p a i r o f means i n a s e t o f p means a r r a n g e d i n o r d e r o f m a g n i t u d e i s c o n s i d e r e d s i g n i f i c a n t i f i t e x c e e d R p , where Rp i s g i v e n by t h e r e l a t i o n Rp = r p where r p i s t h e l e a s t s i g n i f i c a n t s t u d e n t i z e d v a l u e t a k e n f r o m s t a t i s t i c a l t a b l e s f o r t h e d e s i r e d s i g n i f i c a n t l e v e l and d e g r e e s o f f r e e d o m , w h i c h i n t h i s c a s e a r e 5 p e r c e n t and 231 r e s p e c t i v e l y . p = 2,3, n and p i s t h e number o f means b e i n g c o m p a r e d . S 2 i s t h e s a m p l e v a r i a n c e w h i c h i s an e s t i m a t e ofcommon v a r i a n c e e s t i m a t e d f r o m e r r o r mean s q u a r e i n t h e a n a l y s i s o f v a r i a n c e t a b l e . n = a v e r a g e number o f o b s e r v a t i o n s p e r s a m p l e g i v e n by t h e r e l a t i o n u n = ( N 2 - ^ n i 2 ) / ( k - 1)N where N = t o t a l number o f o b s e r v a t i o n s . Duncan's m u l t i p l e r a n g e t e s t f o r Co, C r , Cu N i , and Zn i n t h e f i v e m a j o r u n i t s o f t h e G u i c h o n b a t h o l i t h a r e s u m m a r i z e d i n F i g u r e 5-3. F i g u r e 5-3 shows t h a t c o b a l t i n t h e G u i c h o n C r e e k b a t h o l i t h o c c u r s i n t h r e e sub s e t s . The mean c o b a l t c o n t e n t o f B e t h s a i d a p h a s e i s s i g n i f i c a n t l y d i f f e r e n t f r o m t h e r e s t o f t h e b a t h o l i t h , u n l i k e B e t h l e h e m p h a s e and Chataway v a r i e t y c o b a l t c o n t e n t c a n n o t be d i s t i n g u i s h e d b u t i s s i g n i f i c a n t l y d i f f e r e n t f r o m G u i c h o n v a r i e t y and B o r d e r p h a s e w h i c h t o g e t h e r f o r m an i n d i s t i n g u i s h a b l e c o b a l t p o p u l a t i o n . Chromium d i s t r i b u t i o n i s d i f f e r e n t f r o m t h a t o f c o b a l t i n t h a t Duncan's m u l t i p l e r a n g e t e s t shows t h a t e a c h o f t h e f i v e m a j o r u n i t s o f t h e b a t h o l i t h c o n s i s i t s o f s i g n i f i c a n t l y d i f f e r e n t chromium p o p u l a t i o n s . N i c k e l on t h e o t h e r hand d i v i d e s t h e b a t h o l i t h i n t o f o u r u n i t s , t h e y o u n g e r u n i t s B e t h s a i d a p h a s e , B e t h l e h e m phase and Figure.5-3: Duncan's multiple range test for trace element content i n the f i v e p r i n c i p a l units of the Guichon Creek batholith. Representation method i s that of Matysek et a l , (1983). Refer to text for discussion of the r e s u l t s . 115 C h ataway v a r i e t y w h i c h f o r m s i g n i f i c a n t l y d i f f e r e n t n i c k e l c o n t e n t p o p u l a t i o n s d i f f e r e n t f r o m G u i c h o n v a r i e t y and B o r d e r p h a s e w h i c h a r e u n d i s t i n g u i s h a b l e . C o p p e r shows a v e r y i n t e r e s t i n g d i s t r i b u t i o n w h i c h i s b a s i c a l l y s i m p l e r t h a n o t h e r e l e m e n t s . C o p p e r d i v i d e s t h e b a t h o l i t h i n t o two u n i t s t h a t a r e r e l a t e d t o y o u n g e r p h a s e s ( B e t h s a i d a and B e t h l e h e m ) , and t h a t r e l a t e d t o o l d e r u n i t s ( C h a t a w a y v a r i e t y , G u i c h o n v a r i e t y and B o r d e r p h a s e ) . Z i n c on t h e o t h e r hand shows a r e l a t i v e l y more c o m p l i c a t e d d i s t r i b u t i o n . Z i n c shows t h r e e p o p u l a t i o n e d where B e t h s a i d a p h a s e and Chataway v a r i e t y a r e n o t d i s t i n g u i s h a b l e . G u i c h o n v a r i e t y and B e t h l e h e m p h a s e a r e a l s o i n d i s t i n g u i s h a b l e i n t e r m s o f z i n c c o n t e n t b u t a r e s i g n i f i c a t l y d i f f e r e n t f r o m B o r d e r p h a s e . T h e r e a r e s e v e r a l t h i n g s t h a t need t o be t a k e n i n t o c o n s i d e r a t i o n i n i n t e r p r e t i n g t h e d i s t r i b u t i o n s d e r i v e d f r o m t h e Duncan's m u l t i p l e r a n g e t e s t . The f i r s t and p e r h a p s most i m p o r t a n t i s t h e m i n e r a l o g i c a l c o m p o s i t i o n o f t h e m a j o r u n i t s of t h e b a t h o l i t h . I t has a l r e a d y been s u g g e s t e d f r o m t h e p a r t i t i o n c o e f f i c i e n t s t h a t m i n e r a l o g i c a l c o n t r o l i s a m a j o r f a c t o r i n t h e d i s t r i b u t i o n o f t h e s e e l e m e n t s . I t i s t h e r e f o r e v e r y i n t e r e s t i n g t o f i n d o u t w h e t h e r m i n e r a l o g i c a l d i f f e r e n c e s b e t w e e n t h e m a j o r p h a s e s o f t h e b a t h o l i t h a r e l a r g e enough t o r e f l e c t on t h e r e s u l t s o f t h e Duncan's m u l t i p l e t e s t , i n w h i c h c a s e i t w i l l be e x p e c t e d t o s e p a r a t e t h e b a t h o l i t h i n t o f i v e t r a c e e l e m e n t p o p u l a t i o n d i s t r i b u t i o n s r e l a t e d t o t h e f i v e m a j o r u n i t s i d e n t i f i e d i n t h i s a n l y s i s . The s e c o n d m a j o r f a c t o r whose e f f e c t s may n o t be e a s y t o s e p a r a t e f r o m t h o s e o f 116 m i n e r a l o g i c a l c o m p o s i t i o n i s t h e e f f e c t o f a v o l a t i l e p h a s e . The t h i r d f a c t o r i s t h e s a m p l i n g and a n a l y t i c a l p r o b l e m . I n g e n e r a l , t r a c e e l e m e n t s b e i n g c o n s i d e r e d i n t h i s s t u d y o c c u r i n m i n o r amounts i n a c i d i c i g n e o u s r o c k s l e a d i n g t o t h e p o s s i b i l i t y o f l a r g e s a m p l i n g and a n a l y t i c a l e r r o r s . T h i s p r o b l e m i s q u i t e a p p a r e n t i n s c a t t e r p l o t s ( n o t p r o d u c e d h e r e ) o f t h e s e e l e m e n t s . The e l e m e n t s Co, Cr and N i a r e i n g e n e r a l d e p l e t e d e a r l y f r o m a c r y s t a l l i z i n g magma and a r e i n c o r p o r a t e d p r e f e r e n t i a l l y i n t o c r y s t a l l i z i n g s o l i d s . G e n e r a l l y , N i and Co a r e e n r i c h e d i n t h e same m i n e r a l s t h o u g h t h e N i / C o r a t i o shows t h a t n i c k e l i s a s s o c i a t e d w i t h Mg and Co w i t h F e 2 + . T h i s phenomenon a c c o u n t s f o r t h e d e c r e a s e o f N i / C o r a t i o w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n ( T a y l o r 1 9 6 5 ) . Chromium, on t h e o t h e r h a n d , shows s i m i l a r p r e f e r e n c e s as N i c k e l t h o u g h n i c k e l i s p r e f e r e n t i a l l y i n c o r p o r a t e d i n e a r l y m i n e r a l s l i k e o l i v i n e w h e r e a s Cr i s e n r i c h e d i n p y r o x e n e s and s p i n e l s . T h e r e f o r e , t h e N i / C r r a t i o o f t h e r o c k i s n o t a d i s t i n c t i v e d i f f e r e n t i a t i o n f a c t o r . Though F i g u r e 5-3 shows s l i g h t d i f f e r e n c e s i n d i s t r i b u t i o n o f t h e s e e l e m e n t s i t b a s i c a l l y r e f l e c t s m i n e r a l o g i c a l c o m p o s i t i o n o f t h e u n i t s o f t h e b a t h o l i t h c o n s i d e r e d h e r e . C o p p e r , on t h e o t h e r h a n d , shows a q u i t e d i f f e r e n t and u n i q u e d i s t r i b u t i o n . D i s t r i b u t i o n o f Cu i n t h e G u i c h o n C r e e k b a t h o l i t h i s r e l a t e d t o b i o t i t e a b u n d a n c e . The b i o t i t e c o n t e n t t h r o u g h o u t t h e b a t h o l i t h v a r i e s s l i g h t l y b e t w een u n i t s . I n o t h e r w o r d s , f o r c o p p e r , Duncan's m u l t i p l e t e s t s h o u l d i n d i c a t e one p o p u l a t i o n f o r t h e w h o l e b a t h l i t h . H owever, F i g u r e 5-3 117 shows t h a t c o p p e r c o n t e n t o f t h e b a t h o l i t h i s d i v i s i b l e i n t o two p o p u l a t i o n s , t h a t r e l a t e d t o h y d r o u s u n i t s o f t h e b a t h o l i t h ( B e t h s a i d a and B e t h l e h e m p h a s e s ) and t h a t a s s o c i a t e d w i t h r e l a t i v e l y a n h y d r o u s u n i t s ( G u i c h o n v a r i e t y , Chataway v a r i e t y and B o r d e r p h a s e ) . T h e r e f o r e , c o p p e r d i s t r i b u t i o n must r e f l e c t e f f e c t s o f v o l a t i l e p h a s e i m m i s c i b i l i t y . D i s t r i b u t i o n o f z i n c , on t h e o t h e r h a n d , i s more c o m p l i c a t e d i n t h a t i t does n o t show t h e p a t t e r n o f o t h e r e l e m e n t s . T h i s i s m a i n l y b e c a u s e z i n c p r e f e r s n e i t h e r o c t a h e d r a l o r t e t r a h e d r a l s i t e s . B e c a u s e o f t h i s f u n d a m e n t a l c o m p l i c a t i o n , t h e e f f e c t s o f v o l a t i l e p h a s e on z i n c d i s t r i b u t i o n i s d i f f i c u l t t o e v a l u a t e . CORRELATION MATRICES The e f f e c t s o f a v o l a t i l e p h a s e on t h e d i s t r i b u t i o n o f t r a c e e l e m e n t s d u r i n g t h e c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k B a t h o l i t h has been e v a l u a t e d o n l y t e n t a t i v e l y . I t i s n o t p o s s i b l e t o i s o l a t e e f f e c t s o f t h i s f a c t o r q u a n t i t a t i v e l y b e c a u s e t h e y a r e s u p e r i m p o s e d on c h e m i c a l v a r i a b i l i t y . C o r r e l a t i o n m a t r i c e s o f t h e s e e l e m e n t s i n t h e f i v e m a j o r u n i t s have been e v a l u a t e d ( T a b l e 5 - 5 ( a - e ) ) , w i t h t h e p u r p o s e o f a s s e s s i n g any d i f f e r e n c e s t h a t may r e s u l t w h i c h c a n n o t be r e l a t e d d i r e c t l y t o m i n e r a l o g i c a l v a r i a t i o n s . B e c a u s e o f t h e i r c l o s e c h e m i s t r y , t h e s e e l e m e n t s a r e g e n e r a l l y s t r o n g l y c o r r e l a t e d i n n a t u r a l s y s t e m s . T a b l e s 5a t o 5e h o w e v e r , show t h a t c o r r e l a t i o n c o e f f i c i e n t s o f t h e s e e l e m e n t s i n t h e G u i c h o n C r e e k b a t h o l i t h d i v i d e s t h e b a t h o l i t h i n t o two m a j o r u n i t s : TABLE 5 - 5 ( a ) CORRELATION MATRIX FOR TRANSITION ELEMENTS IN BORDER PHASE (DATA LOG-TRANSFORMED) Co Cr Cu N i Zn Co 1.0000 0.5313 0.4303 0.8350 0.3444 Cr 1. 0, 0, 0. 0000 2481 7195 1978 Cu 1.0000 0.4426 0.3141 N i 1.0000 0.2560 Zn 1.0000 n = 96 TABLE 5 - 5 ( b ) CORRELATION MATRIX FOR TRANSITION ELEMENTS IN GUICHON VARIETY (DATA LOG-TRANSFORMED) Co Cr Cu N i Zn Co 1.0000 0.7347 0.5409 0.8444 0.5071 Cr 1.0000 0.3347 0.8854 0.5642 Cu 1.0000 0.5318 0.1727 N i 1.0000 0.4526 Zn 1.0000 n = 60 TABLE 5 - 5 ( c ) CORRELATION MATRIX FOR TRANSITION ELEMENTS IN CHATAWAY VARIETY (DATA LOG-TRANSFORMED) Co Cr Cu N i Zn Co 1.0000 Cr 0.1344 1.0000 Cu 0.0173 0.1519 1.000 N i 0.5928 0.5970 0.0468 1.0000 Zn 0.0822 0.0136 0.1375 0.0731 1.0000 TABLE 5 - 5 ( d ) CORRELATION MATRIX FOR TRANSITION ELEMENTS IN BETHLEHEM PHASE (DATA LOG-TRANSFORMED) Co Cr Cu N i Zn Co 1.0000 Cr 0.2525 1.0000 Cu 0.0886 0.4044 1.0000 N i 0.8212 0.4460 0.3607 1.0000 Zn 0.4709 0.0831 0.5666 0.6388 1.0000 TABLE 5 - 5 ( e ) CORRELATION MATRIX FOR TRANSITION ELEMENTS IN BETHSAIDA PHASE (DATA LOG-TRANSFORMED) Co Cr Cu N i Zn Co - 1.0000 Cr 0.4951 1.0000 Cu -0.2495 -0.0406 1.0000 N i 0.2402 0.3865 0.0273 1.0000 Zn 0.6969 0.5669 -0.1529 0.2942 1.0000 n - 38 120 1) t h a t w i t h h i g h p o s i t i v e c o r r e l a t i o n c o e f f i c i e n t s ( B o r d e r p h a s e and G u i c h o n v a r i e t y ) , and 2) t h a t w i t h r e l a t i v e l y l o w i r r e g u l a r c o r r e l a t i o n c o e f f i c i e n t s ( B e t h l e h e m and B e t h s a i d a p h a s e s ) . C hataway v a r i e t y shows t r a n s i t i o n a l c h a r a c t e r i s t i c s b etween t h e two u n i t s . The i r r e g u l a r and l o w c o r r e l a t i o n c o e f f i c i e n t s i n y o u n g e r p h a s e s a r e c o n s i d e r e d t o be r e l a t e d t o d i f f e r e n c e s i n s o l u b i l i t y o f t h e s e e l e m e n t s i n an a q u e o u s p h a s e , h e n c e t h e i r e x t r a c t i o n f r o m t h e m e l t by t h e f l u i d p h a s e a f f e c t e d t h e i r a b s o l u t e c o n t e n t s i n c r y s t a l l i z i n g s o l i d s . CONCLUSION D i s t r i b u t i o n p a t t e r n s o f Co, C r , Cu, N i and Zn d u r i n g t h e c r y s t a l l i z a t i o n o f G u i c h o n C r e e k B a t h o l i t h r o c k s s u g g e s t t h a t t h e s e e l e m e n t s d e c r e a s e d i n c o n c e n t r a t i o n i n r e s i d u a l m e l t w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n as e v i d e n c e d by t h e i r h i g h c o n c e n t r a t i o n s i n o u t e r more m a f i c u n i t s ( B o r d e r phase and G u i c h o n v a r i e t y ) and t h e i r l ow c o n c e n t r a t i o n s i n y o u n g e r p h a s e s . The d e c r e a s e i n e l e m e n t a l c o n c e n t r a t i o n f r o m m a r g i n t o c o r e o f t h e b a t h o l i t h i s c o n s i s t e n t w i t h h i g h o c t a h e d r a l s i t e p r e f e r e n c e e n e r g i e s o f t h e s e e l e m e n t s . B u l k p a r t i t i o n c o e f f i c i e n t s a r e c o n s i s t e n t w i t h t h e above o b s e r v a t i o n , t h e y a r e much l a r g e r t h a n one i n o l d e r b a t h o l i t h i c p h a s e s w h i c h a l s o s u g g e s t s p r e f e r e n c e f o r e a r l y c r y s t a l l i z i n g s o l i d s . But p a r t i t i o n c o e f f i c i e n t s f a l l b e l o w one i n y o u n g e r p h a s e s , a f e a t u r e b e s t a t t r i b u t e d t o v o l a t i l e 121 p h a s e i m m i s c i b i l i t y . T h i s i s a l s o c o n s i s t e n t w i t h l o w and i r r e g u l a r c o r r e l a t i o n c o e f f i c i e n t s f o r t h o s e e l e m e n t s i n y o u n g e r p h a s e s , a f a c t o r a t t r i b u t e d t o d i f f e r e n t s o l u b i l i t i e s o f t h e s e e l e m e n t s i n a q u e o u s p h a s e , hence d e g r e e o f e x t r a c t i o n f r o m m e l t . The d i s t r i b u t i o n o f c o p p e r i n t h e G u i c h o n C r e e k B a t h o l i t h a s shown by t h e Duncan's m u l t i p l e r a n g e t e s t d i v i d e s t h e b a t h o l i t h i n t o two c o p p e r p o p u l a t i o n s , t h e f i r s t r e l a t e d t o o l d e r u n i t s ( B o r d e r p h a s e , G u i c h o n v a r i e t y and Chataway v a r i e t y ) and t h e s e c o n d t o y o u n g e r u n i t s ( B e t h l e h e m and B e t h s a i d a p h a s e s ) . T h e d i s t r i b u t i o n o f c o p p e r t h e r e f o r e i s a t t r i b u t e d t o v o l a t i l e p h a s e a c t i v i t y . C o p p e r , t h o u g h e x p e r i m e n t a l e v i d e n c e i s l a c k i n g , seems t o be t h e m e t a l i n t h e s e g r o u p s most p r e f e r e n t i a l l y p a r t i t i o n e d t o w a r d s c h l o r i d e r i c h s o l u t i o n s ( K h i t a r o v e t a l . , 1 9 8 2 ) . 122 REFERENCES B a r s u k o v , V.L., and D u r a s o v a , N.A., 1966: M e t a l C o n t e n t and M e t a l l o g e n i c S p e c i a l i z a t i o n on I n t r u s i v e R o c k s i n t h e r e g i o n s o f S u l f i d e - c a s s e t -e r i t e D e p o s i t s ( M i a o - C h a n g and S i k h o l e - A l i n ) . G e o c h . I n t e r n . , V. 3, p. 97- 1 0 7 . Burnham, W.C, 1979: Magmas and H y d r o t h e r m a l f l u i d s . " I n t h e G e o c h e m i s t r y o f H y d r o t h e r m a l Ore D e p o s i t s " , H.L. B a r n e s , e d . , New Y o r k : H o l t R i n e h a r t and W i n s t o n , p. 71-136. 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N a t u r e , V. 184, p. 44. 125 CHAPTER SIX CONCLUSIONS AND IMPLICATIONS FOR EXPLORATION A v a i l a b l e g e o l o g i c a l and w h o l e r o c k d a t a f o r t h e G u i c h o n C r e e k b a t h o l i t h p r o v i d e s a so u n d b a s i s f o r t h e d e v e l o p m e n t o f a c r y s t a l l i z a t i o n model f o r t h e p a r e n t magma. S e v e r a l new a p p r o a c h e s t o t h e i n t e r p r e t a t i o n o f w h o l e r o c k c h e m i c a l d a t a l e a d t o g e n e r a l s u p p o r t f o r e x i s t i n g p o s t u l a t e d m o d e l s , w i t h a d d i t i o n a l d e t a i l i n a few c a s e s . I n p a r t i c u l a r , t h e b a t h o l i t h a p p e a r s t o have f o r m e d by c o n s o l i d a t i o n o f a s i n g l e magma o f a n d e s i t i c c o m p o s t i o n ( e q u i v a l e n t t o G u i c h o n v a r i e t y ) . B o t h p e r f e c t f r a c t i o n a l and s u r f a c e e q u i l i b r i u m c r y s t a l l i z a t i o n seem t o h ave o p e r a t e d . The enormous magma body was e m p l a c e d s t i l l l a r g e l y m o l t e n a t s h a l l o w d e p t h s u n d e r s o l i d c o u n t r y r o c k s . Due t o t h e l i q u i d n a t u r e o f t h e magma, i t may have s u r g e d i n w a r d s u n d e r t h e he a v y o v e r l y i n g r o c k s . T h i s s u r g i n g i n w a r d s of t h e magma body u n d e r l i t h o s t a t i c p r e s s u r e w o u l d be g r e a t e r a t t h e c e n t r e t h a n a t ends t h u s c r e a t i n g a s a u c e r - s h a p e of t h e b a t h o l i t h w i t h two d o m e - l i k e s t r u c t u r e s a t b o t h e n d s . The n o r t h e r n dome s t r u c t u r e was a t h i g h e r e l e v a t i o n t h a n t h e s o u t h e r n e n d. The c o n t a c t o f t h e h o t m a t e r i a l w i t h c o o l e r c o u n t r y r o c k s r e s u l t e d i n c r y s t a l l i z a t i o n f r o m t h e m a r g i n i n w a r d s . T h i s manner of c r y s t a l l i z a t i o n r e s u l t e d i n t h e f o r m a t i o n of an o u t e r c r y s t a l l i n e c o v e r as B o r d e r p h a s e w h i c h p r o t e c t e d t h e r e s t o f 126 t h e magma f r o m b o t h h e a t and m a t e r i a l l o s s , t h u s r e d u c i n g t h e r a t e o f c r y s t a l l i z a t i o n , as e v i d e n c e d by an i n c r e a s e i n g r a i n s i z e t o w a r d s t h e c o r e o f t h e b a t h o l i t h . D i f f e r e n t i a t i o n o f t h e p a r e n t magma r e f l e c t e d by s y s t e m a t i c v a r i a t i o n i n t h e c o m p o s i t i o n o f t h e b a t h o l i t h f r o m m a f i c m a r g i n a l r o c k s t o a c i d i c c o r e , was c o n t r o l l e d l a r g e l y by t h e m i n e r a l a s s e m b l a g e h o r n b l e n d e - p l a g i o c l a s e - b i o t i t e . The a s s e m b l a g e a l s o p l a y e d a m a j o r r o l e i n t h e d i s t r i b u t i o n o f t r a c e e l e m e n t s d u r i n g t h e c r y s t a l l i z a t i o n o f t h e b a t h o l i t h . The e l e m e n t s B a, S r and Rb show d i s t r i b u t i o n p a t t e r n s t h a t r e f l e c t f o r t h e m a j o r p a r t t h e a b o v e a s s e m b l a g e . P l o t s o f Ba v / s Rb, and S r v / s Rb show i n g e n e r a l a d e c r e a s e o f Ba and S r w i t h p r o g r e s s i v e c r y s t a l l i z a t i o n w h i l e Rb shows an i n c r e a s e f r o m B o r d e r p h a s e t o H i g h l a n d V a l l e y p h a s e and t h e n d e c r e a s e s . T h i s f e a t u r e i s a l s o r e f l e c t e d by t h e K/Rb r a t i o w h i c h d e c r e a s e s f r o m B o r d e r p h a s e t o G u i c h o n V a r i e t y and t h e n i n c r e a s e s r a p i d l y t o w a r d s t h e c o r e o f t h e b a t h o l i t h . The r e s u l t i n g p a t t e r n s a r e a t t r i b u t e d t o p r e f e r e n t i a l p a r t i t i o n i n g o f Rb t o w a r d s t h e v o l a t i l e f l u i d s whose e v o l u t i o n c o i n c i d e d w i t h c r y s t a l l i z a t i o n o f t h e c o r e o f t h e b a t h o l i t h . The b a t h o l i t h magma w h i c h i s e s t i m a t e d t o c o n t a i n a b o u t 3 w e i g h t p e r c e n t o f w a t e r was e m p l a c e d b e t w e e n d e p t h s o f 5 and 9 k i l o m e t r e s . A t s u c h d e p t h t h e magma w o u l d be s a t u r a t e d w i t h w a t e r a f t e r a b o u t 72 p e r c e n t c r y s t a l l i z a t i o n ( e q u i v a l e n t t o c r y s t a l l i z a t i o n o f H i g h l a n d V a l l e y p h a s e ) . A s s u m i n g t h a t c o m p l e x z o n i n g i n p l a g i o c l a s e c r y s t a l s was r e l a t e d t o e p i s o d i c r e l e a s e o f v o l a t i l e f l u i d s , t h e r e s t r i c t i o n o f c o m p l e x l y z o n e d 127 p l a g i o c l a s e t o y o u n g e r p h a s e s ( B e t h l e h e m and B e t h s a i d a ) as o p p o s e d t o n o r m a l z o n i n g i n o l d e r p h a s e s ( B o r d e r and H i g h l a n d V a l l e y ) , i s c o n s i s t e n t w i t h r e l e a s e o f v o l a t i l e f l u i d s a t t h e l a t e s t a g e s o f c r y s t a l l i z a t i o n o f t h e G u i c h o n C r e e k b a t h o l i t h magma. M i n e r a l i z a t i o n i n t h e G u i c h o n C r e e k b a t h o l i t h i s m a i n l y c o n f i n e d t o t h e c e n t r e o f t h e b a t h o l i t h , and i s a s s o c i a t e d w i t h f r a c t i o n i n g d y k e s and e x p l o s i o n b r e c c i a s . T hese f e a t u r e s t o g e t h e r w i t h t h e t i m i n g o f v o l a t i l e p h a s e r e l e a s e w h i c h c o i n c i d e d w i t h c r y s t a l l i z a t i o n o f t h e c e n t r e o f t h e b a t h o l i t h s u g g e s t t h a t m a g m a t i c p r o c e s s e s p l a y e d a m a j o r r o l e i n t h e e v o l u t i o n o f a s s o c i a t e d p o r p h y r y c o p p e r d e p o s i t s . D i s t r i b u t i o n o f o r e - f o r m i n g e l e m e n t s among t h e m a j o r r o c k u n i t s o f t h e b a t h o l i t h i s w e l l i l l u s t r a t e d by c o p p e r d i s t r i b u t i o n , t h e p r i n c i p a l m e t a l i n a s s o c i a t e d p o r p h y r y t y p e m i n e r a l d e p o s i t s . The r e l a t i v e d e p l e t i o n o f c o p p e r i n y o u n g e r p h a s e s i s c l e a r l y t h e r e s u l t o f i t s p r e f e r e n t i a l p a r t i t i o n i n g i n t o an i m m i s c i b l e v o l a t i l e p h a s e t h a t u l t i m a t e l y became t h e o r e - f o r m i n g f l u i d . B e c a u s e o f g r e a t c o m p o s i t i o n a l v a r i a b i l i t y o f t h e G u i c h o n C r e e k b a t h o l i t h r o c k s , c o p p e r b a c k g r o u n d p o p u l a t i o n i s v a r i a b l e e v e n w i t h i n i n d i v i d u a l p h a s e s . I n B o r d e r p h a s e , c o p p e r v a r i e s f r o m a b o u t 35 ppm t o o v e r 135 ppm w h i l e d e c r e a s i n g t o between 15 and 80 ppm i n B e t h s a i d a p h a s e . I m m i s c i b l e v o l a t i l e f l u i d s d u r i n g c r y s t a l l i z a t i o n o f s i l i c a t e magma, i m p r i n t s c h a r a c t e r i s t i c t r a c e e l e m e n t p a t t e r n s on t h e o v e r a l l t r a c e e l e m e n t d i s t r i b u t i o n p a t t e r n s . The 128 v a r i a t i o n o f e l e m e n t s Ba, S r and Rb t o g e t h e r w i t h K/Rb r a t i o shows p a t t e r n s r e l a t e d t o v o l a t i l e i m m i s c i b i l i t y h e n c e c a n be u s e d t o i d e n t i f y t h e t i m i n g o f v o l a t i l e r e l e a s e . The t i m i n g o f v o l a t i l e p h a s e r e l e a s e d u r i n g c r y s t a l l i z a t i o n o f s i l i c a t e magma d e t e r m i n e s t h e c o m p o s i t i o n o f t h e a s s o c i a t e d m i n e r a l d e p o s i t s . E a r l y s a t u r a t i o n and r e l e a s e o f v o l a t i l e f l u i d s i n c a l c - a l k a l i n e magmas r e s u l t i n c o p p e r - r i c h o r e d e p o s . i t s , w h e r e a s l a t e s a t u r a t i o n l e a d s t o c o p p e r - p o o r and l a r g e l i t h o p h i l e e l e m e n t -r i c h d e p o s i t s , s u c h as molybdenum, u r a n i u m a n d / o r t i n - t u n g s t e n . T h i s i s b e c a u s e l a t e s a t u r a t i o n l e a d s t o r e m o v a l o f c o p p e r by e a r l y c r y s t a l l i n e s o l i d s , and l e a d t o c o p p e r - p o o r d e p o s i t s w h e r e a s e a r l y s a t u r a t i o n w o u l d l e a d t o p r e f e r e n t i a l p a r t i t i o n i n g o f c o p p e r i n t o e v o l v i n g f l u i d s t h u s l e a d i n g t o c o p p e r - r i c h d e p o s i t s . 129 Appendix (A-l) Calculations of bulk d i s t r i b u t i o n c o e f f i c i e n t s of Ba, Sr and Rb i n major units of the ba t h o l i t h , using constant mineral-melt p a r t i t i o n c o e f f i c i e n t s summarized from Table 3-1. In Border phase =0.55x0.36+0.03x6.12+0.18x0.001+0.07 x6.36+0.44x.10 Ba =0.831 D„ =0.55x2.84+0.03x3.87+0.18x0.0001+0.17x0.12+0.10x0.22 Sr =1.709 D R b=0. 55x0.048+0.66x0.03+3.26x0.07+0.10x0.22+0.18x0.0001 =0.296 In Guichon Variety D =0.5x0.36+.10x6.12+0.09x6.36+0.044x.08+0.OOOlx.18 =1.368 D„ =0.5x2.84+.10x3.87+0.09x0.12+0.08x0.22+0.18x0.001 Sr =1.835 D=0.5x0.048+.10x0.66+3.26x0.09+0.08x0.014+0.18x0.0001 Kb =0.385  In Chataway Variety D„ =0.36x0.54+6.12x.11+6.36x0.05+0.07x0.044+0.18x0.0001 Ba =1.189 D„ =0.54x2.84+.11x3.87+0.05x0.12+0.07x0.22+0.18x0.0001 Sr =1.981 D =0.54x0.048+.11x0.66+0.05x3.26+0.07x0.014+0.18x0.0001 Rb =0.263  In Bethlehem Phase D =0.36x0.49+6.12x.10+0.03x6.36+0.04x0.044+0.18x0.0001 Ba =0.981 D S r Rb =0. 49x2. 84+0.10x3.87+0.12x0.03+0.04x0. 22+0.18x0.0001 =1. 791 =0. 49x0. 048+0.10x0.66+3.26x0.03+0.04x. 014+0.18x0.0001 =0. 188 Appendix (A-l) (Continued) In Bethsaida Phase Dfia=0.52x0.36+0.11x6.12+0.06x6.36+0.004x0.044+0.18x0.0001 =1.242 =0- 52x2. 84+0.11x3.87+0.12x0.06+0.004x0.22+0.18x0. 0001 =1. 91 =0. 1 52x0. 048+0.11x0.66+0.06x3.26+0.004x0.014+.18x. 0001 =0. 293 131 Appendix (A-2) Calculations of theoretical trace element d i s t r i b u t i o n trends i n the Guichon Creek batholithic rocks were carried out using constant mineral proportion (Xi) equivalent to mineral mode of Guichon Variety, and constant mineral-melt p a r t i t i o n c o e f f i c i e n t s (Kd). Calculations were carried out for both Rayleigh (Cl/Co=FD~]-) and surface equilibrium (Cl/Co=l/(F+D(l-F)) models Mineral Xi * ha KRb * K S r Plagioclase 0.50 0.36 0.048 2.84 K-feldspar 0.10 6.12 0.66 3.87 B i o t i t e 0.09 6.36 3.26 0.12 Hornblende 0.08 0.044 0.014 0.22 Quartz 0.18 0.0001 0.0001 0.0001 * Kd values taken from McCarthy et a l . (1976); Arth Bulk d i s t r i b u t i o n coefficients D = ZXiK^ d D„ =0.5x0.36+0.1x6.12+0.09x6.36+0.08x0.044+0.0001x0.18 Ba =1.37 D_ =0.5x2.84+0.1x3.87+0.09x0.12+0.22x0.08+0.18x0.0001 Sr =1.84 DRb=0.5x0.048+0.66x0.1+3.26x0.09+0.08x0.014+0.0001x0.18 =0.385 Using the above calculated bulk d i s t r i b u t i o n c o e f f i c i e n t s , variation of trace elements i n residual melt during c r y s t a l l i z a t i o n of Guichon Creek batholith magma were calculated as^ghown below. Original concentrations of the magma (Co) are Co =53ppm; Co^a=633 ppm and Co^r=594 ppm residual melt concentrations (CI) calculated for Rayleigh model are: Rb Ba Sr Cl= =53x( .9) .385--1_ =57 633x( .9)1- 37-'1=609 594x( • 9 ) 1 ' 84-'1=544 Cl= =53x( • 8) .385--1 =61 633x( .8) 1- 37-' l=583 594x( .8) 1 ' 84-"1=493 Cl= =53x( .7) .385--1_ =66 633x( 37-+-555 594x( .7) 1- 84-'1=440 Cl= =53x( .6) .385--1_ =73 633x( 37--1=524 594x( .6) 1- 84-ml=387 Cl= =53x( .5) .385--1_ 81 633x( 37-'1=490 594x( 84-"1=332 Cl= 53x( .4) .385--1_ •93 633x( 37- 1=451 594x( .4) 1- 84- 1=275 Cl= 53x( .3) .385--1_ 111 633x( 37- 1=405 594x( • 3 ) 1 ' 84-'1=216 Cl= 53x( .2) .385--1_ 142 633x( 37- 1=349 594x( . 2 ) 1 - 84-^=154 Cl= 53x( .1) • 385_ -1= 218 633x( . i ) 1 - 37- 1=270 594x( . I ) 1 " 84- 1=86 132 Appendix (A-2) (continued) Concentration of elements in c r y s t a l l i z i n g solids calculated for 10 percent Rayleigh model c r y s t a l l i z a t i o n i n t e r v a l s . Cs/Co=DFD-1 Rb Ba Sr Cs =53x0.385x(. .9) .385--1. =22 633x1. ,37x(. 37--1_ =834 594x1. ,84(. 9 ) 1 . 8 4 - 1 = 1 0 0 ( ) Cs> =53x0.385x(. 8) .385--1_ =23 633x1. 37x(. 37--1_ = 799 594x1. 84(. 8 ) 1 . 8 4 - l = g 0 6 CS: =53x0.385x(. 7) .385--1_ =25 633x1. 37x(. 7 ) 1 ' 37--1_ = 760 594x1. 84x( .7) 1- 8 4- 1=810 Cs= =53x0.385x(. 6) .385--1_ =28 633x1. 37x(. 37--1_ =718 594x1.84(. 6) 1- 8 4- 1=712 Cs = 53x0.385x(. 5) .385--1= =31 633x1. 37x(. 5 ) 1 . 37-•1_ =671 594x1. 84x( Cs= =58x0.385x(. 4) .385--1_ =36 633x1. 37x(. 4 ) 1 ' 37-•1_ =6.8 594x1. 84x( .4) 1- 8 4- 1=506 Cs= =53x0.385x(. 3) .385--1_ :43 633x1. 37x(. 3 ) 1 . 37-•1_ 555 594x1. 84x( > 3 ) 1 . 8 4 - 1 = 3 9 8 Cs= =53x0.385x(. 2) .385--1= 55 633x1. 37x(. 2 ) 1 . 37-•1_ 478 594x1. 84x( .2) 1' 8 4 _ 1=283 Cs= =53xo.385x(. 1) .385-•1_ 84 633x1. 37x(. i ) 1 - 37-•1_ 370 594x1. 84x( . l ) 1 - 8 4 " 1 ^ Concentrations of elements i n residual melts at 10 percent surface equilibrium intervals where Cl=Co/(F+(1-F)D) Rb Ba Sr Cl=53/(.9+(.385x.1))=57 633/(.9+(l.368x.1))=611 594/(.9+(l.84x.1))=548 Cl=53/(.8+(.385x.2))=60 633/(.8+(l.368x.2))=590 594/(.8+(l.84x.2))=509 Cl=53/(.7+(.385x.3))=65 633/(.7+(l.368x.3))=570 594/(.7+(l.84x.3))=474 Cl=53/(.6+(.385x.4))=70 633/(.6+(l.368x.4))=552 594/(.6+(l.84x.4))=445 Cl=53/(.5+(.385x.5))=77 633/(.5+(l.368x.5))=535 595/(.5+(l.84x.5))=418 Cl=53/(.4+(.385x.6))=84 633/(.4+(l.368x.6))=519 594.(.4+(l.84x.6))=395 Cl=53/(.3+(.385x.7))=93 633/(. 3+(l. 368x. 7) )=503 594/( . 3+(.l. 84x. 7) )=374 Cl=53/(.2+(.385x.8))=104 633/(.2+(l.368x.8))=489 594.(.2+(l.84x.8))=355 Cl=53/(.l+(.385x.9))=119 633/(.1+(1.368x.9))=476 594/(.1+(1.84x.9))=338 133 Appendix (A-2) (continued) Concentrations of elements i n c r y s t a l l i z i n g solids at 10 percent surface equilibrium intervals where Cs=DCo/(F+(1-F)D) Rb Cs=(0.385)53/(.9+(.lx.385))=22 Cs=(.385)53/(.8+(.2x.385))=23 Cs=(.385)53/(.7+(.3x.385))=25 Cs=(.385)(53)/(.6+(.Ax.385))=27 Cs=(.385)53/(.5+(.Sx.385))=29 Cs=(.385)53/(.4+(.6x.385))=32 Cs=(.385)53/(.3+(.7x.385))=36 Cs=(.385)53/(.2+(.8x.385))=40 Cs=(.385)53/(.l+(.9x.385))=46 Ba (1.368)633/(.9+(.lxl.368))=835 (1.368)633/(.8+(.2x1.368))=807 (1.368)633/(.7+(.3x1.368))=780 (1.368)633/(.6+(.4x1.368))=755 (1.368)633/(.5+(.5x1.368))=731 (1.368)633/(.4+(.6x1.368))=709 (1.368)633/(.3+(.7xl.368))=689 (1.368)633/(.2+(.8x1.368))=669 (1.368)633/(.l+(.9x1.368))=651 Sr (1.84)594(.9+(.lxl.84))=1008 (1.84)594(.8+(.2x1.84))=936 (1.84)594 (.7+(.3xl.84))=873 (1.84)594/(.6+(.4x1.84))=818 (1.84)(594)/(.5+(.5x1.84))=770 1.84 (594)/(.4+(.6xl.84))=727 1.84(594)/(.3+(.7x1.84))=688 (1.84)594/(.2+(.9x1.84))=653 (1.84)594/(.l+(.9x1.84))=622 134 Appendix (B) Multiple range test calculations for elements Cu, Co, Cr. Ni and Zn i n major phases of the batholith. Cu Symbol Ni log X E(logXi) I(logXi) Border phase E 96 1.93 186.10 380.48 Guichon phase D 60 1.93 115.70 230.79 Chataway phase C 33 1.87 62.50 121.87 Bethlehem phase B 9 1.32 11.88 18.87 Bethsaida phase A 38 1.33 50.58 82.29 Sum Total (N) 236 426.76 834.30 C.T. = ( Z ( l o g X i ) ) 2 = (426. 76, 2 = • 771.71 N 236 SSA = Z(ZlogXi) 2 - C.T. = [(186. D 2 + (115.7) 2 + (62.5) 2 + ( N. i 96 60 33 + (50 •58) 2] - 771.71 38 = 13.54 k n 2 SST = Z E (logXi) - C.T. = [834.30 - 771.71] i=l j = l = 62.59 SSE = SST - SSA = 62.59 - 13.54 = 49.05 S 2 = SSE = 49.05 = 0.2123 N-K 236-5 S 2 = SSA _ 13.54 _ 1 F T " T T " 135 Cu Appendix (B) (continued) F = S^/S2 = 3.385/0.2123 = 15.94 F0.05(4,231)=2.37 Since calculated F value exceed the c r i t i c a l F value at 0.05 percent significant l e v e l then at least two of the mean copper content i n phases of the batholith are s i g n i f i c a n t l y d ifferent. n = (N 2 - En 2 / (K-l)N = 43 Sx = jS2/n = 0.2123/43 = 0.0703 P Rp rp=SxRp 2 2.77 0.195 3 2.92 0.205 4 3.02 0.212 5 3.09 0.217 E-B=l.93-1.32=0.61<rc E-A=l.93-1.33=0.60<r, E-C=l.93-1.87=0.06>r, D-B=l.93-1.32=0.61<r, 4 D-A=l.93-1.33=0.60<r2 C-B=l.87-1.32=0.55<r3 C-A=l.87-1.33=0.54<r2 A-B=l.33-1.32=0.01>r0 E s i g n i f i c a n t l y different from B E s i g n i f i c a n t l y different from A E not s i g n i f i c a n t l y different from C D s i g n i f i c a n t l y different from B D s i g n i f i c a n t l y different from A C s i g n i f i c a n t l y different from B C s i g n i f i c a n t l y different from A A not s i g n i f i c a n t l y different from B Appendix (B) (continued) Ni Symbol n (logX) Z(logXi) Z(lo gXi) Border phase E 96 1 231 118 .14 153 .27 Guichon variety D 60 1 136 68 15 83 .49 Chataway variety C 33 0 909 30 84 29 .30 Bethlehem phase B 9 0. 436 4 93 3 .32 Bethsaida phase A 38 0. 128 9 84 7 .54 236 231 90 276 .92 136 C.T. = [Z(logXi)] 2/N = (231.9) 2 = 227.87 236 k SSA = ,E ( Z ( l o g X i ) ] 2 - C.T. = [(118.14) 2+(68.15) 2+(30.84) 2+(4.93) 2+(9.84) 2]-C.T. 1 Ni 96 60 33 9 38 = 28.993 k n SST = Z Z(logXi) -C.T.=(276.92-227.87) i=l j = l = 49.05 SSE = SST-SSA = 49.05-28.993 = 20.057 2 S = SSE/N-K=20.057/231=0.0868 sj = SSA/K-1=28.993/4=7.25 F = sJ/S2=7.25/0.0868=83.5 Calculate F value exceeds c r i t i c a l F value at 0.05 percent si g n i f i c a n t l e v e l and hence at least two means are dif f e r e n t . S = f i r = 0.0868 = 0.045 43 Ni P Rp rp=SxRp 2 2.72 0.122 3 2.92 0.131 4 3.02 0.134 5 3.09 0.139 E-A=1.231-E-B=1.231-E-C=1.231-E-D=1.231-D-A=1.136-D-B=1.136-D-C=1.136-C-A=0.909-C-B=0.909-B-A=0.436--0.128=1, -0.436=0. -0.909=0, •1.136=0. •0.128=1. •0.436=0. •0.909=0. •0.128=0. 0.436=0. 0.128=0. 103<rt 795<r^ 322<r, 095>r, i 008<r. 700<r. 227<r2 781<r„ 473<r2 308<ro E s i g n i f i c a n t l y different from A E s i g n i f i c a n t l y different from B E s i g n i f i c a n t l y different from B E not s i g n i f i c a n t l y different from D D s i g n i f i c a n t l y different from A D s i g n i f i c a n t l y different from B D s i g n i f i c a n t l y different from C C s i g n i f i c a n t l y different from A C s i g n i f i c a n t l y different from B B s i g n i f i c a n t l y different from A 137 Appendix (B) (continued) Cr Symbol n (logX) E(logXi) Z((logXi) 2) Border phase E 96 1.41 131.08 193.98 Guichon variety D 60 1.17 70.18 93.70 Chataway variety C 33 0.912 31.01 29.50 Bethlehem phase B 9 0.75 6.75 6.05 Bethsaida phase A 38 0.236 10.98 8.04 250.00 331.27 CT. = ( Z ( l o g X i ) 2 = (250) 2 N 236 = 264.83 k 2 = [(131.08) 2 , 2 „ 2 x 2 SSA = I (I(logXi)) - CT. = +(70.18) +(31.01) +(6 • 75) i=l Ni 96 60 33 9 +(10.98)2]-250 38 = 48.44 k n _ SST = Z E(logXi) -C.T.=(331.27-250)=81.27 1=1 j = l SSE = SST-SSA=81.27-48.44 = 32.83 S 2 = SSE/N-K=32.83/231=0.1421 S 2 = SSA/K-1=48.44/4=12.11 F = S2/S2=12.11/0.1421=85 Calculated F value exceed F ( c r i t i c a l ) at 0.05 percent s i g n i f i c a n t l e v e l , hence at least two of the means i n phases of the batholith are different. 0.1421/43=0.057 Appendix (B) (continued) Cr 2 3 4 5 2.77 2.92 3.02 3.09 0.158 0.166 0.172 0.176 E-A=l.41-0.236=1.174>r5; E s i g n i f i c a n t l y different from A E-B=l.41-0.75=0.66 >r^; E s i g n i f i c a n t l y different from B E-C=l.41-0.912=0.498>r3; E s i g n i f i c a n t l y different from C E-D=l.41-1.17-0.24>r2; E s i g n i f i c a n t l y different from D D-A=l.17-0.236=0.934>r4; D s i g n i f i c a n t l y different from A D-B=l.17-0.75=0.42>r3; D s i g n i f i c a n t l y different from B D-C=l.17-0.912=0.258>r2; D s i g n i f i c a n t l y different from C C-A=0.912-0.236=0.676>r3; C s i g n i f i c a n t l y different from A C-B=0.912-0.75=0.162>r2; C s i g n i f i c a n t l y different from B B-A=0.75-0.236=0.514>r; B s i g n i f i c a n t l y different from A P Rp rp=SxRp Co Symbol n_ (logXi) Z(logXi) Z((logXi) Border phase (E) 96 1.244 119.37 151.50 Guichon variety (D) 60 1.156 69.34 81.85 Chataway variety (C) 33 0.908 32.86 33.87 Bethlehem phase (B) 9 0.857 7.71 6.76 Bethsaida phase (A) 38 0.721 26.43 22.72 Sum Total 236 255.71 296.70 ii = 43 CT. = ( E ( l o g X i ) ) 2 = N 277.07 k 2 2 , 2 , v 2 SSA = Z (Z(logXi)) • -C.T.=[(119.37) +(69.34) +(32.86) +(7. 71) i = l n. l 96 60 33 9 +(26.43) ]-277.07 38 =9.502 139 Appendix (B) (continued) k n i SST = E E i=l j=l(logXi) -CT=(296.70-277.07) = 19.63 SSE = SST-SSA=19.63-9.502 =10.128 2 S L = SSE/N-K=10.128=0.0438 S 2 = SSA/K-1=9.502/4=2.376 F = S2/S2=2.376/0.0438=54.24 Calculate F value exceed F ( c r i t i c a l ) at 0.05 percent si g n i f i c a n t l e v e l . Co Sx s_ fi = 0.0438 = 0.03192 43 P = Rp = rp=SxRp = 2 2.77 0.088 3 2.92 0.093 4 3.02 0.096 5 3.09 0.099 E-A=l.244-0.721=0.523>rc E-B=l. 244-0. 857=0. 3 8 7 ^ E-C=l.244-0.908=0.336> r, E-D=l.244-1.156=0.088=r„ D-A=l.156-0.721=0.435>r, D-B=l.156-0.857=0.299>r3 D-C=l.156-0.908=0.248>r2 C-A=0.908-0.721=0.187> r 3 C-B=0.908-0.857=0.051<ro E s i g n i f i c a n t l y different from A E s i g n i f i c a n t l y different from B E s i g n i f i c a n t l y different from C E not s i g n i f i c a n t l y different from D D s i g n i f i c a n t l y different from A D s i g n i f i c a n t l y different from B D s i g n i f i c a n t l y different from C C s i g n i f i c a n t l y different from A C not s i g n i f i c a n t l y different from B 140 Appendix (B) (continued) Zn Symbol n logX (logXi) E(logXi) Border phase E 96 1.867 178.27 332.96 Guichon variety D 60 1.679 100.73 170.92 Chataway variety C 33 1.58 52.4 83.51 Bethlehem phase B 9 1.708 15.37 26.43 Bethsaida phase A 38 1.569 59.62 95.43 236 406.39 709.25 C.T. = (406.39) 2 = 699.8 236 SSA = (I(logXi)) 2-C.T.=[(59.62) 2+(15.37) 2+(52.4) 2+(100.73) 2 n i 38 9 33 60 +(178.27)2]-699.8 96 = 3.391 SST = SST-SSA=9.45-3.391=6.059 S 2 = SSE/N-K=6.059/231=0.02623 S 2 = SSA/K-1=3.391/4=0.848 F = S2/S2=0.848/0.02623=32.3 Calculate F value exceed F ( c r i t i c a l ) at -.05 percent s i g n i f i c a n t l e v e l , hence at least two of means are dif f e r e n t . Sx 0.02623 = 0.0247 43 P 2 3 4 5 Rp 2.77 2.92 3.02 3.09 rp=SxRp 0.068 0.072 0.075 0.076 Appendix (B) (continued) Zn E-A=l.867-1.569=0.298>r5; E s i g n i f i c a n t l y different from A E-C=l.867-1.58=0.287>r4; E s i g n i f i c a n t l y different from C E-D=l.867-1.679=0.188>r3; E s i g n i f i c a n t l y different from D E-B=l.867-1.708=1.159>r2; E s i g n i f i c a n t l y different from B B-A=l.708-1.569=0.139>r4; B s i g n i f i c a n t l y different from A B-C=l.708-1.58=0.128>r3; B s i g n i f i c a n t l y different from C B-D=l.708-1.679=0.029<r2; B i s not s i g n i f i c a n t l y different from D D-A=l.679-1.569=0.ll>r3; D i s s i g n i f i c a n t l y different from A D-C=l.679-1.58=0.99>r2; D i s s i g n i f i c a n t l y different from C C-A=l.58-1.567=0.011<r; C i s not s i g n i f i c a n t l y different from A 142 APPENDIX(C) MAJOR AND TRACE ELEMENT DATA OF THE GUICHON CREEK BATHOLITH, KINDLY SUPPLIED BY Dr.W.J. McMILLAN, OF BRITISH COLUMBIA MINISTRY OF MINES, ENERGY AND PRE PETROLEUM RESOURCES: GEOLOGICAL BRANCH. B o r d e r P h a s e N T S ID S i 0 2 A 1 2 0 3 MgO CaO Na , ,0 9 2 1 2E BM 2 57 , , 73 17 , 33 2 . , 7 0 6 , . 24 3 . 9 8 2 9 2 1 2E J N 1 51 . . 0 3 17 . 56 6 . , 7 4 10, , 13 3 . 46 9 2 1 2E J N 7 57 . , 0 2 18 . 0 7 3 . , 14 6 , , 8 4 4 . 2 6 4 9 2 1 2E J N 9 5 6 . , 4 3 17 . 41 3 . . 73 6 . . 8 0 3 . 9 4 0 9 2 1 6A BM 7 54 . , 25 17 . 42 3 . . 7 2 6 , . 7 0 3 . 8 4 5 9 2 1 6A J N 15 5 3 . 22 16 . 74 3 . 94 6 , ,81 3 . 2 5 0 9 2 1 6G BM 3 5 0 . 6 5 17 . 78 5 . , 25 8 .71 3 . 55 9 2 1 6 G BM 5 46 . 24 19 . 4 3 6 . , 78 1 1 , ,71 2 . 2 1 9 2 1 6 G BM 7 5 9 . , 10 16 . 77 3 . . 0 8 6 , . 0 8 3 . 8 1 9 2 1 6 G BM 9 6 0 . , 39 16 . 94 2 , . 8 5 5, .51 4 . 0 2 9 2 1 6 G BM 1 1 6 2 . , 16 16 . 8 5 2. 8 9 5, . 8 5 3 . 8 2 9 2 1 6 G BM 13 5 5 . . 9 9 17 . 48 3 . . 8 2 7 , . 5 2 3 . 74 9 2 1 GG BM 16 4 9 . , 4 0 1 5 . , 5 0 5 . . 4 6 9 . 0 2 3 . 6 8 921 6 G J N 1 5 5 . , 8 7 18 . 63 3 , 74 7 , . 18 4 . 194 9 2 1 6 G J N 4 5 5 . , 8 2 17 . 6 2 4 , . 16 7 . 32 3 . 8 0 9 2 1 6G J N - 6 56 . . 7 3 17 , 01 3 , . 8 0 6, . 8 0 3 . 46 9 2 1 6G J N 8 56 . , 53 17 . 14 3 . 5 6 6 . 9 5 3 . 75 9 2 1 6 H BR 105 4 9 , . 16 18 , 25 5 . 4 9 9 . 5 4 3 . 7 5 3 9 2 1 6 H BR 107 51 . 7 1 18 . , 83 4 . 52 8 . 54 4 . 3 7 6 9 2 1 6 H J N 6 56 . 59 19, . 4 2 3 . 0 2 7 . 0 8 4 . 2 7 7 9 2 1 7F EG 1 61 . 4 6 16 , 13 2 . 3 0 4 . 42 3 . 9 9 0 9 2 1 1 0 D BR 36 58 . 78 16 . 8 7 3 . 44 6 . 54 4 . 0 7 6 9 2 1 1 0 D BR 4 1 58 . 77 16 . 48 3 . 0 9 6 . 10 4 . 1 6 1 9 2 1 1 0 D EG 1 6 6 . 6 9 15 . 73 1 . 52 3 . 7 6 4 . 0 4 7 9 2 1 1 1A J N 8 57 . 8 0 16 .81 3 . 19 6 . 2 0 3 . 9 2 7 9 2 1 1 1B BM 2 58 . 37 16, . 47 3 . 19 6 .21 3 . 3 1 8 9 2 1 1 1B BM 4 58 . 76 16, . 6 0 3 . 25 6 . 28 3 . 531 9 2 1 1 1B BM 6 58 . 9 6 16 , . 84 3 . 34 6 . . 46 3 . 5 2 1 9 2 1 1 1B BM 8 55 . 6 9 16 . . 82 3 , . 6 0 6 . 9 3 3 . 3 9 9 2 1 1 1B BM 13 55 . 83 17 , . 6 3 3 . 4 4 7 . 0 8 3 . 6 2 9 2 1 1 1B BM 16 57 . 10 16 . 0 0 3 . 0 5 6 . 3 0 3 . 4 6 9 2 1 1 1B J N 2 58 . 4 7 16 .34 3 , . 19 6 . 36 3 . 8 7 7 9 2 1 1 1B J N 4 59 . 9 3 15 . 9 2 2 . 6 8 5 .31 3 . 4 5 2 9 2 1 1 1B J N 6 57 . 9 3 16 . 7 9 3 . 4 0 6 . 3 9 3 . 6 2 2 9 2 1 1 1B J N 8 6 0 . 0 3 16, . 5 4 3 . 42 6 . 34 3 . 7 7 1 9 2 1 1 1B J N 10 61 . 1 1 15 . 6 4 1 . 9 3 5 . 32 4 . 197 9 2 1 1 1B J N 12 6 5 . 12 15 . 36 2 . 19 4 . 9 5 3 . 3 6 7 9 2 1 1 1B J N 14 5 9 . 24 16 . 39 3 . 0 3 6 . 0 3 3 . 3 0 6 9 2 1 1 1B J N 17 57 . 0 7 16 . 8 7 3 . 6 6 6 . 79 3 . 6 8 3 9 2 1 1 1B J N 19 64 . 25 15 . 25 2 . 37 4 . 8 8 3 . 5 0 0 9 2 1 1 18 J N 21 58 . 24 16 . 6 6 3 . 0 2 5 . 9 8 3 . 4 1 5 9 2 1 1 1B J N 24 5 9 . 6 6 15 . 88 3 . 0 7 6 . 0 0 3 . 5 6 6 9 2 1 1 1B J N 26 58 . 7 0 14 . 7 0 3 . 44 7 . 18 2 . 76 9 2 1 1 1B J N 28 61 . 8 0 15 . 9 4 3 .91 2 . 9 2 5 . 136 9 2 1 1 1C BM 2 47 . 19 18 . 84 4 . 8 5 10. . 9 0 2 . 2 7 2 9 2 1 1 1G BM 8 5 8 . 8 0 16 . 33 3 . 39 6 . 38 3 . 2 2 8 9 2 1 1 1G J N 12 5 8 . 95 15 . 9 8 3 . 17 6 . . 32 3 . 0 9 2 9 2 1 1 1G J N 22 64 . 38 15 . 86 2 . 19 4 , 9 6 3 . 4 4 8 9 2 1 1 1A J N 8 57 . 8 0 16 .81 3 . 19 6 , , 2 0 3 . 9 2 7 9 2 1 1 1B BM 1 58 . 9 1 16 .81 3, . 5 8 6 . . 6 9 3 . 4 1 5 9 2 1 1 1B BM 2 58 . 37 16 . 47 3 . 19 6 . ,21 3 . 3 1 8 9 2 1 1 1B BM 3 57 . 4 7 16 .61 3 . 5 8 6 . . 8 5 3 . 0 2 9 2 1 1 1B BM 4 5 8 . 76 16 . 6 0 3 . 25 6 . 28 3 . 5 3 1 9 2 1 1 1B BM 5 52 . 9 3 18 . 0 0 4 , . 42 8 . 27 3 . 5 5 K 2 0 T i 0 2 MnO F e 2 ° 3 FeO F e . 2°3 E a s t N o r t h ( t o t ) 1 . 7 0 5 0 . 8 7 8 0 . 1 1 7 6 . 26 27 . 22 10 . 6 9 0 . 2 6 0 . 8 5 0 . 14 8 .91 27 . 4 6 9 . 79 1 . 4 3 5 0 . 6 9 2 0 . 1 1 3 6 . 74 35 . 5 0 13 , .41 1 . 4 2 5 0 . 778 0 . 100 6 .91 33 . 52 1 1 , 58 1 . 1 4 1 0 . 7 2 0 0 . 105 6 . 4 4 32 . 27 10 . 0 5 1 . 5 1 3 1 . 0 8 4 0 . 121 7 . 4 7 31 . 63 1 1 , , 12 0 . 7 0 1 . 3 0 0 . 18 10 . 39 32 . 24 12 . 9 0 0 . 8 1 1 . 0 8 0 . 1 3 8 . 6 7 3 . 0 5 3 . 0 0 21 . 26 2 3 . 5 8 1 . 75 0 . 9 4 0 . 1 2 6 . 8 6 3 . 7 8 2 . 24 2 0 . 35 23 . 8 3 1 . 8 7 0 . 6 2 0 . 0 9 5 . 4 2 2 . 9 0 2 . 53 19 . 5 8 2 0 . 7 2 1 . 8 2 0 . 73 0 . 1 1 6 . 29 4 . 5 7 2 . 39 22 . 0 3 18 . 0 8 1 .41 0 . 9 6 0 . 1 3 8 . 3 5 3 . 1 1 2 . 4 9 21 . 4 3 18 , . 16 1 . 23 2 . 5 2 0 . 1 8 12 . 0 0 15 . 23 3 3 . 17 1 . 154 0 . 8 0 2 0 . 108 6 . 9 7 15 . 5 8 33 . 6 8 0 . 8 3 0 . 8 5 0 . 1 2 7 . 3 5 16 . 36 32 , . 9 4 1 . 59 0 . 8 6 0 . 1 1 7 . 0 5 13 . 39 37 . 9 7 1 . 26 1 . 0 2 0 . 1 2 7 . 6 0 14 . 23 36 . 9 6 0 . 3 5 2 1 . 156 0 . 155 10 .41 15 . 13 36 , . 74 0 . 3 8 9 0 . 9 6 0 0 . 134 8 . 2 0 16 . 32 36 , . 4 6 2 . 0 4 7 0 . 8 2 0 0 . 0 9 3 6 . 2 9 14 . 9 2 35 . , 4 0 2 . 6 7 0 0 . 7 1 3 0 . 0 8 1 5 .51 13 . 77 35 , , 14 1 . 6 9 0 0 . 757 0 . 0 8 4 6 . 12 16 . 9 3 29 , , 6 5 2 . 3 0 0 0 . 782 0 . 1 1 4 6 . 38 16 . 79 31 , 6 6 2 . 6 8 0 0 . 4 6 5 0 . 0 5 2 3 . 3 8 14 . 8 9 29 , , 6 8 1 . 9 3 5 0 . 8 2 8 0 . 1 1 1 6 . 7 2 14 . 4 9 31 , . 16 2 . 0 1 3 0 . 8 3 6 0 . 108 6 . 79 1 1 . . 9 0 33 , , 8 0 1 . 6 6 6 0 . 9 1 4 0 . 109 7 . 3 4 2 .51 4 . 18 14 . 57 4 1 . 28 1 .771 0 . 9 3 0 0 . 123 7 . 36 12 . 9 0 3 9 . . 9 7 1 . 9 7 0 . 9 3 0 . 1 4 8 .01 12 . 8 8 39 , 2 0 1 . 4 5 0 . 8 4 0 . 1 3 7 . 48 1 1 . 77 4 0 , ,51 1 . 6 5 0 . 9 1 0 . 13 7 . 4 3 1 1 . 4 6 39 , , 6 2 1 . 5 6 5 0 . 7 5 3 0 . 125 6 . 75 1 1 . 23 38 . 4 7 2 . 2 9 0 0 . 8 1 3 0 . 0 9 6 5 . 9 9 1 1 . 6 2 37 , , 5 2 1 . 7 1 0 0 . 8 9 1 0 . 133 7 . 0 9 10 . 8 6 37 . .21 1 . 7 3 6 0 . 8 3 8 0 . 1 1 1 6 . 78 19, . 3 2 3 0 . . 16 1 . 2 7 8 0 . 9 2 1 0 . 164 6 . 6 6 19 . 8 2 28 , , 44 1 . 4 7 4 0 . 4 9 4 0 . 109 5 .41 18 , . 8 8 28 . , 3 3 1 . 3 2 6 0 . 8 1 0 0 . 139 7 . 5 5 0 .91 1 . 5 2 18, . 27 31 . 7 5 1 . 5 9 4 0 . 8 9 1 0 . 1 1 1 7 . 0 5 3 .54 2 . 351 18. . 4 9 29 18 1 . 727 0 . 8 0 6 0 . 136 6 . 6 6 36 , .51 34 . 5 5 1 . 9 1 2 0 . 8 9 7 0 . 103 6 . 6 9 2 . 8 0 2 . 4 0 36 , , 45 4 0 . 9 2 1 . 9 6 3 0 . 9 4 4 0 . 1 1 7 6 . 9 2 2 98 2 . 29 36 , , 0 9 35 . 21 0 . 6 1 0 . 59 0 . 2 0 8 .01 34 . 15 4 5 . 7 0 0 . 156 0 . 5 8 3 0 . 0 9 9 7 . 34 33 , , 0 2 51 . 10 0 . 5 0 6 0 . 7 5 8 0 . 178 10 . 0 6 3 2 , , 4 2 5 0 . 8 5 1 . 6 1 3 0 . 8 0 5 0 . 1 1 3 6 . 6 7 3 2 , , 34 5 2 , 0 0 1 . 8 6 8 0 . 9 1 1 0 . 128 7 . 24 34 , 6 9 44 . 4 3 1 . 7 1 2 0 . 5 7 3 0 . 0 9 6 5 . 18 4 . . 10 3 . 0 0 18 . , 75 4 9 . 19 1 . 9 3 5 0 . 8 2 8 0 . 1 1 1 6 . 7 2 3 . . 4 7 2 . 8 7 18 . 5 0 51 . 14 1 . 5 0 6 0 . 8 3 0 0 . 105 6 . 7 8 4 . . 2 3 2 . 0 8 1 1 . 64 4 5 . 25 2 . 0 1 3 0 . 8 3 6 0 . 108 6 . 7 9 1 1 . 32 44 . 9 5 1 . 4 8 0 . 7 8 0 . 1 2 7 . 5 5 1 0 . 28 43 . 74 1 . 6 6 6 0 . 9 1 4 0 . 109 7 . 34 4 . 4 5 2 . 4 0 9 . 67 43 . 18 0 . 8 6 0 . 8 7 0 . 15 8 , . 4 8 1 0 . 0 0 4 6 . 36 Border Phase (con't) NTS ID S10 2 A1 20 3 921 1 1B BM 6 58. .96 16 . 84 921 1 1B BM 7 56. .37 17 . ,43 921 1 18 BM 8 55. .69 16. ,82 921 1 1B BM 12 59 .67 16. . 17 921 1 1B BM 13 55 .83 17 . 63 921 1 1B BM 15 60 .47 15 .62 921 1 1B BM 16 57 . 10 16, .00 9211 1B BM 17 57 .82 16, .53 921 1 1B ON 2 58 .47 16 .34 921 1 1B ON 3 57 .64 17 . 22 921 1 1B ON 4 59 .93 15 .92 921 1 1B ON 5 59 .58 16 .33 921 1 1B ON 6 57 .93 16 . 79 921 1 1B ON 7 57 .01 17 .32 921 1 1B ON 8 60 .03 16 .54 921 1 1B ON 9 48 .97 17 .72 921 1 1B ON 10 61 . 1 1 15 .64 921 1 1B ON 1 1 59 . 48 16 .60 921 1 1B ON 12 65 . 12 15 .36 921 1 1B ON 13 56 . 70 17 .20 921 1 1B ON 14 59 . 24 16 .39 921 1 1B ON 15 59 .32 16 .91 921 1 1B ON 17 57 .07 16 .87 921 1 1B ON 18 58 .54 16 .66 921 1 1B ON 19 64 .25 15 .25 921 1 1B ON 20 55 .99 16 .82 921 1 1B ON 21 58 .24 16 .66 921 1 1B ON 22 49 . 15 18 , . 78 921 1 1B ON 24 59. .66 15, .88 921 1 1B ON 25 51 . 14 20, .84 92111B ON 26 58. .70 14 , .70 921 1 1B ON 27 68 .62 13, .97 921 1 1B ON 28 61 .80 15 .94 921 1 1B ON 29 60 . 17 17 . 12 921 1 1C BM 2 47, . 19 18 . 84 921 1 1G BM 6 62. .72 16 , .49 921 1 1G BM 8 58 . 80 16, .33 921 1 1G BM 14 66. . 17 13. ,92 921 1 1G ON 12 58. .95 15. 98 921 1 1G ON 21 56. .93 15. ,85 921 1 1G ON 22 64 . 38 15. 86 MgO CaO Na 20 KjO T10 2 MnO 3, ,34 6. .46 3 .521 1 .771 0. 930 0. 123 3. 84 7. 39 3 .346 1 .374 0. 826 0. 1 17 3. ,60 6. 93 3.39 1 .97 0.93 c i. 14 3. ,33 6. ,25 3 .913 1 .609 0. 742 0. 111 3. ,44 7. ,08 3.62 1 .45 0.84 0 >. 13 2 .81 5. 29 3 .669 2 .277 0. 741 0. 104 3 . ,05 6. ,30 3.46 1 .65 0.91 0 M 3 3. , 16 6. ,31 3 .573 1 .610 0. 947 0. 123 3 , 19 6. ,36 3 .877 1 .565 0. 753 0. 125 3 .23 6 .81 3 .780 1 .399 0. 770 0. 1 16 2 .68 5. .31 3 .452 2 . 290 0. 813 0. 096 3 .49 6. .35 3 .464 1 .746 0. 895 0. 1 10 3 .40 6 .39 3 .622 1 .710 0. 891 0. 133 3 .80 6. 98 3 .766 1 . 343 0. 746 0. 1 14 3 ,42 6 .34 3 .771 1 . 736 0. 838 0. 1 1 1 5, .30 9 ,25 3.84 I 0.93 1 I . 17 0 i . 14 1 .93 5. .32 4 . 197 1 .278 0. 921 0. 164 3 .02 5. , 58 3 .633 1 .835 0. 773 0. 112 2 . 19 4. ,95 3 .367 1 .474 0. 494 0. 109 3 .56 6 ,74 3 .544 1 .425 0. 927 0. 121 3 .03 6 .03 3 .306 1 .326 0. 810 0. 139 3 .' 18 6 . 14 3 .544 1 .832 0. 850 0. 106 3 .66 6 .79 3 .683 1 .594 0. 891 0. 1 1 1 2 .79 6 .25 3 .417 1 .434 0. 962 0. 161 2 .37 4, .88 3 .500 1 .727 0. 806 0. 136 3 .93 7, .08 3 .074 1 .452 0. 954 0. 136 3 .02 5, 98 3 .415 1 .912 0. 897 0. 103 4 , .96 9. .20 3 .620 0 .554 1. 167 0. 173 3 . 07 6. 00 3 .566 1 .963 0. 944 0. 117 4 . 23 10. .99 3 .557 0 .298 0. 746 0. 143 3, ,44 7. , 18 2.76 I D.61 0.59 0 i. 20 1 , .79 3. .20 5 .623 0 .374 0. 571 0. 051 3 .91 2. 92 5 . 136 0 . 156 0. 583 0. 099 2 .93 5. 92 3.94 1 .27 0.81 0 >. 10 4 , .85 10, ,90 2 .272 0 .506 0. 758 0. 178 2. ,59 5. .41 3 .962 1 .388 0. 704 0. 094 3 . 39 6. 38 3 .228 1 .613 0. 805 0. 113 1 . .93 3. 88 3 .520 2 .485 0. 651 0. 090 3. , 17 6. .32 3 .092 1 .868 0. 911 0. 128 3. .64 6. 55 3 . 160 1 .485 0. 984 0. 134 2 . 19 4. ,96 3 .448 1 .712 0. 573 0. 096 Fe 2 0 3 FeO F e 2 ° 3 E a s t North (tot) 7 , .36 4 , .66 2, . 18 9. . 17 46 .25 7 , .54 4, .72 2. , 29 9. ,57 45, .01 8. .01 9. .47 47, .79 6 , .08 3 .47 2 . 22 14 , .69 45 .26 7 , .48 13, .51 52 .75 5 . 94 3, .47 2. ,09 12, .33 53 . 1 1 7 . ,43 1 1 , .23 54 .88 7. , 19 4, .53 2. . 16 1 1 . .54 54 .92 6 , 75 3, .49 2. .87 14 . 95 46 . 77 6 .92 13 .91 46 .44 5 .99 3 .67 1 .91 10 . 30 50 .95 6 .88 4 .22 2, .19111 .82 48 .90 7, .09 4 .09 2 .54 1 1 .80 48 .24 6. .57 3 .90 2, . 24 14 .21 45 .00 6 .78 4 .04 2 . 29 14 .06 43 .09 9. .76 14 .76 43 .61 6. .66 3, . 37 2 .91 9, .58 52 .69 6 , 43 3 .95 2 , .04 10, .09 52 .92 5, .41 3 .64 1 , . 36 9, .31 55 . 39 7 , 32 4 , .50 2 .32 10. .51 54 .68 7 .55 4 .05 3, .05 9 .58 53 .53 6 .74 2 .95 3 .46 13 .42 49 .90 7, .05 4 .23 2 . 35 14. .81 53 .51 7 , .98 4 .70 2, .76 14 .49 55 .08 6. .66 4 . 10 2 . 1 1 14, . 1 1 55 .06 8 . , 37 5, .47 2 . 29 13, .96 53 .53 6 .69 4 .02 2 22 10, .93 48 .78 10. ,27 5. .94 3 , 67 9, ,51 50 .49 6 . ,92 4 . , 23 2 , 22 13 , .87 50 .45 6 . , 12 4 . , 34 1 , . 30 15 , 30 52 .83 8 . 01 16. .85 54 , .59 3 . 15 1 .54 1 . 44 16, .69 55 . 27 7 . 34 4 , . 10 2 . 78 16. .55 52 .91 5. .84 12, . 75 43 .69 10, ,06 6 . 18 3 . 19 6 , 77 48 . 1 1 5 , 64 3 28 1 . .99112. 22 59, .81 6 , 67 4 . 34 1 . .85 12 , 18 57 .33 4 , 94 2, ,80 1 , 83 10, ,01 61 , .82 7 , 24 4 , . 29 2 . ,47 16 . 01 66 .88 7. 75 5. ,05 2. 15 14. ,55 65 , .21 5. 18 3 . ,00 1 . 84112. 98 63 , .63 Guichon V a r i e t y NTS 10 SIO 2 A l 2 ° 3 MgO CaO Na 0 K 2 ° TIO. MnO F e 2 ° 3 FeO F e 2 ° 3 East North (tot) 921 2E . ON 6 58 . 42 16 . 96 3 . 06 6 . 08 4 . 053 1 . 735 0. 701 0. 095 5 . 90 33. 28 12 . 38 921 2E 'ON 10 56 . 76 18 . 02 3. 51 6 . 59 4 . 050 1 . 559 0. 719 0. 105 6. 54 31 . 49 13. 26 921 6A BM 19 62 . 06 16 . 94 2. 76 5. 69 4 . 157 1 . 736 0. 615 0. 087 5. 50 2. ,75 2 . 44 26 . 05 16 . 03 921 6G JN 2 54. 35 18 . 78 4 . 24 7 . 81 3. 909 0. 950 0. 673 0. 108 7 . 17 3 .85 2 . 89 15. 43 40. 38 921 6H BR 86 63. 55 16 . 43 1 . 94 5. 17 4 . 761 1 . 608 0. 52 1 0. 076 4 . 34 18 . 76 41 . 53 921 7C EG 21 63 . 40 16 . 53 1 . 69 4 . 34 4 . 212 2 . 180 0. 500 0. 070 3. 99 1 .99 1 . 78 36. 35 21 . 84 921 7D BL 3 64 . 95 16 . 39 1 . 95 4 . 31 4 . 217 2. 563 0. 460 0. 073 4 . 14 2 .06 1 . 85 33. 17 17 . 42 921 7D BL 6 63 . 87 17 . 02 1 . 58 5 . 03 4 . 587 1 . 458 0. 454 0. 079 4 . 02 1 .83 1 . 98 28 . 94 21 . 10 921 7D ON 5 61 . 30 16. 26 3. 02 5. 50 4. 132 1 . 958 0. 609 0. 098 5. 30 2 . 47 2 . 56 31 . 97 15. 68 921 7D JN 8 64 . 56 17 . 32 1 . 53 4 . 27 4 . 426 2 . 146 0. 432 0. 068 3. 60 1 .66 1 . 76 27 . 46 20. 80 921 7E BR 50 60. 01 16 . 61 3 . 10 5. 77 3. 967 2 . 049 0. 670 0. 088 5 . 62 30. 02 39 . 44 921 7E BR 51 60. 60 16. 48 2 . 77 5. 45 4 . 082 2 . 155 0. 631 0. 078 5 . 34 29. 62 39; 45 921 7E BR 52 61 . 23 16. 40 2 . 76 5. 26 4 . 231 1 . 884 0. 623 0. 091 5. 29 30. 75 41 . 38 921 7E BR 531 62 . 62 16 . 27 2 . 55 4 . 94 3. 912 2. 557 0. 604 0. 083 5. 04 32 . 59 40. 17 921 7E BR 532 64 . 21 16 . 31 1 . 72 4 . 1 1 4 , 064 2 . 602 0. 486 0. 060 4 . 03 32 . 59 40. 17 921 7E BR 54 58 . 95 18 . 07 2. 78 6 . 09 4 . , 105 1 . 841 0. 636 0. 089 5 . 79 33 . 23 40. 45 921 7E BR 57 63 . 48 17 . 37 2 . 04 5 , 1 1 4 . ,534 1 765 0. 489 0. 078 4 . 41 30. 60 35. 74 921 7E BR 62 64 . 75 16. 19 1 . 72 4 . ,29 4. .241 2 . 247 0. 463 0. 072 4 . 02 32 . 49 35 . 46 921 7E BR 63 66 . 68 15. 85 1 . 26 3. 53 4. , 192 2 . ,497 0. 360 0, 063 3 . 08 34 . 02 34 . ,58 921 7E BR 66 66 . 24 15 . 72 I . .4 1 3 .77 4 , . 106 2 . 502 0. 401 0. ,062 3 . , 38 35. 24 36 . 17 921 7E BR 67 63 . 36 16 . 46 1'. 83 4 . ,68 4 , 322 2 , 109 0. 481 0. 074 4 18 33. 18 36 . 36 921 7E BR 68 64 . 83 15 . 77 2 .03 4 . , 32 4 .085 2 .506 0. 588 0. ,069 4 , 47 33. ,20 39. ,42 921 7E BR 74 64 . 65 16 . 07 1 . 94 4 , .43 4 , 277 2 , . 266 0. 530 0. .074 4 , . 23 33. 22 33. 20 921 7E BR 78 64 .53 15. 32 1 . .94 4 . 19 3 .990 2 .611 0. 561 0, ,068 4 , 25 35 , 54 30. .61 921 7F BR 71 62 .41 15 .57 2 .76 5 .08 3 .894 2 .555 0. 681 0 .077 5 . 10 36 82 32 . ,64 921 7F ON 1 66 .63 16 .04 1 .48 3 .73 4 .03 2 .68 0.41 0.06 3 . 45 35 .99 28 . 24 921 7F ON 2 63 .99 16, .55 2 . 27 4 .72 4 . 23 2.29 0.54 0.07 4 .45 36 .44 29, .98 92110D BM 3 63 . 17 16 .43 2 .59 4 .57 3 .89 2 .68 0.64 0.08 4 .93 27 .60 45 .46 92110D BR 17 59 .65 17 . 29 3 .05 5 . 82 4 . 209 1 .911 0. .672 0 .087 5 .44 30 . 12 47 . 39 92110D BR 18 60 .93 16 .50 2 .92 5 .32 3 .912 2 . 328 0. . 729 0 .092 5 . 13 28 .93 46 .84 92110D BR 20 67 . 18 14 .67 1 . 56 3 .20 3 .649 3 .530 0 .601 0 .063 3 .71 29 .66 45 .25 92110D BR 21 62 .02 16 . 13 2 .57 4 .85 3 .967 2 .824 0 .687 0 .048 4 . 79 30 .02 45 .46 92110D BR 22 61 .02 16 . 19 2 .86 5 . 16 3 .959 2 . 708 0 .721 0 .090 5 . 14 30 .32 46 .81 92110D BR 222 60 .98 16 . 32 2 .87 5 . 14 4 .024 2 .743 0 . 709 0 .090 5 . 18 30 . 32 46 .81 92110D BR 23 60 .57 16 .47 2 .83 5 .34 4 .033 2 .542 0 .674 0 .083 5 . 17 31 .62 46 .47 921100 BR 24 61 . 72 15 .94 2 .68 4 . 84 3 .889 2 .807 0 .676 0 .077 4 . 74 31 .61 47 .52 92110D BR 25 60 .45 16 .63 2 .90 5 .37 4 .603 2 .269 0 .717 0 .060 4 .96 33 .24 47 . 44 92110D BR 26 61 .50 16 . 32 2 . 79 4 .99 4 .030 2 . 762 0 .686 0 .080 4 .99 33 .52 46 .86 92110D BR 27 63 .76 15 . 56 1 .95 3 .96 3 .832 3 . 255 0 .629 0 .066 4 . 18 34 . 22 42 .70 921100 BR 28 61 .84 16 . 18 2 .67 4 .88 4 .003 2 .772 0 .658 0 .080 4 .90 34 .21 42 . 1 1 92110D BR 29 61 .61 16 .42 2 .82 5 .07 4 .080 2 . 561 0 . 720 0 .087 5 . 15 31 . 72 44 . 37 921 10D BR 30 62 . 10 16 . 54 2 .71 5 .09 3 .973 2 .349 0 .693 0 .096 5 .26 31 .58 43 .76 921100 BR 31 59 .92 17 . 16 2 .92 5 .71 4 . 139 2 .063 0 . 733 0 .083 5 .48 31 .66 42 .40 921100 BR 32 63 .05 15 .94 2 .44 4 .61 3 .942 2 .701 0 .682 0 .075 4 .89 30 . 16 42 .89 92110D BR 33 60 .00 16 .83 3 .05 5 .91 3 .885 1 .984 0 .668 0 .096 5 .63 28 .85 43 .21 92110D BR 34 61 .01 16 .36 2 .73 5 . 33 4 . 131 2 . 150 0 .675 0 .091 5 .36 29 .47 42 . 22 92110D BR 35 63 .50 15 . 63 2 .48 4 .46 3 .912 2 .871 0 .675 0 .072 4 .90 34 .61 43 . 1 1 92110D BR 38 59 .66 16 .37 2 .74 5 .51 4 .517 2 .415 0 . 722 0 .077 5 .32 30 .68 50 . 79 92110D BR 39 60 .50 15 . 79 3 . 1 1 5 .37 4 .048 2 . 275 0 .713 6 . 122 5 .67 31 .70 49 .51 92110D BR 43 57 .09 16 .90 3 . 34 6 .51 4 .081 2 . 136 0 .714 0 . 1 18 6 .86 32 .96 49 .98 92110D BR 46 65 . 18 15 . 78 1 . 39 2 .55 5 . 144 2 .482 0 . 324 0 .069 3 . 18 29 . 36 49 .87 92110D BR 48 61 .97 15 .91 2 .53 4 .60 4 . 106 2 .668 0 .634 0 .084 5 .25 30 . 74 51 .96 92110D BR 49 63 . 12 16 .60 1 .86 4 . 75 5 .913 0 .514 0 .473 0 .030 3 .30 27 . 15 48 .71 Guichon V a r i e t y ( c o n ' t ) NTS I D s i o 2 A l 2 ° 3 9 2 1 1 1A BM 2 58 . 15 16 . 72 9 2 1 1 1 A BM 4 5 5 . 14 16 . 0 9 9 2 1 1 1 A EG 16 57 . 55 17 . 34 9 2 1 11A JN 3 6 1 . 6 0 16 . 3 1 9 2 1 1 1A JN 4 6 6 . 19 15 . 5 3 9 2 1 1 1 B BM 9 5 9 . 0 5 17 . 4 4 9 2 1 1 1 B JN 1 6 7 . 64 14 . 5 3 9 2 1 1 1 B JN 16 6 1 . 20 17 . 2 0 MgO CaO N a 2 0 K 2 0 T 1 0 2 MnO 3 . 6 6 6 . 0 3 3 . 5 3 4 2 . 8 9 9 0 . 8 6 3 0 . 0 8 4 5 . 1 5 7 . 0 2 3 . 6 6 2 . 4 1 1 . 0 4 0 . 1 1 3 . 2 7 6 . 0 2 4 . 2 7 0 1 . 4 1 7 0 . 7 7 3 0 . 0 7 3 3 . 3 3 5 . 4 4 3 . 8 9 5 2 . 2 6 1 0 . 7 0 0 0 . 0 9 2 1 . 9 9 3 . 9 7 3 . 8 9 8 2 . 7 4 9 0 . 5 2 8 0 . 0 6 5 3 . 0 6 5 . 9 0 4 . 0 2 0 1 . 7 3 3 0 . 7 0 1 0 . 0 9 3 1 . 5 8 4 . 0 2 3 . 6 9 5 2 . 1 9 5 0 . 6 5 6 0 . 1 0 3 1 . 7 2 5 . 2 8 4 . 2 5 2 . 3 7 0 . 7 6 0 . 1 1 F e 2 0 3 FeO F e 2 0 3 E a s t N o r t h ( t o t ) 5 . 8 9 2 . 4 6 3 . 1 6 2 2 . 4 3 4 9 . 0 9 7 . 2 9 2 0 . 0 7 4 8 . 5 2 6 . 3 0 2 6 . 3 4 4 7 . 4 6 5 . 8 1 3 . 0 7 2 . 3 9 1 8 . 1 5 4 2 . 9 7 4 . 1 3 2 . 0 2 1 . 8 9 1 9 . 3 0 4 5 . 5 8 5 . 8 8 3 . 2 1 2 . 3 1 1 7 . 1 1 4 4 . 5 5 5 . 0 8 3 . 0 3 1 . 7 2 1 6 . 7 6 4 6 . 7 3 5 . 2 0 1 7 . 5 2 51 . 2 8 Chataway Variety NTS I D s i o 2 A 1 2 ° 3 MgO CaO Na 0 K 2 0 T I O . MnO F e 2 ° 3 FeO Fe, 2 ° 3 E a s t N o r t h ( t o t ) 921 6A BM 16 6 6 , , 3 0 15 , ,95 1 . 8 9 4 . . 0 3 4 . 0 3 0 2 . 7 5 6 0 . 4 0 3 0 . 0 6 6 3 . 8 1 1 . 8 3 1 . 77 25 . 6 9 17 , . 8 9 921 6A BM 17 67 , . 29 16 , , 6 1 1 . 22 4 . , 2 0 4 . 5 4 5 1 . 387 0 . 373 0 . 0 5 5 3 . 16 1 . 4 3 1 . 57 25 . 8 2 17, . 8 8 9 2 1 6A JN 1 6 5 . , 32 17 , , 08 1 , . 5 1 4 . 15 4 . 3 9 2 . 2 7 0 . 4 1 0 . 0 6 3 . 56 24 . 2 1 2 0 . . 73 9 2 1 6A JN 2 6 3 . , 27 17 , , 28 2 . 0 9 5 . . 16 4 . 24 1 . 9 0 0 . 4 9 0 . 0 7 4 . 44 23 . 8 4 19, . 5 8 9 2 1 6A JN 9 62 . 8 1 16 , 87 2 . 0 9 4 . 93 4 . 4 4 0 1 . 8 1 2 0 . 5 2 9 0 . 0 8 7 4 . 6 1 2 . 2 0 2 . 16 21 , . 2 8 26 89 9 2 1 6G BM 1 6 2 . 82 15 , , 93 2 . 0 0 4 . , 24 3 . 9 5 8 2 . 4 2 7 0 . 5 2 9 0 . 0 6 7 4 . 18 2 . 16 1 . 77 16 .93 38 . 9 1 9 2 1 6G BM 2 6 3 . . 5 6 17 . , 04 2 , . 0 0 4 , . 6 6 4 . 3 5 2 . 1 1 0 . 5 2 0 . 0 7 4 . 3 6 17 . 0 1 4 0 . 0 2 9 2 1 6H BM 1 6 3 . 2 0 17 . 4 9 1 . 9 7 4 . 8 2 4 . 3 9 2 . 0 7 0 . 4 8 0 . 0 8 4 . 4 4 18 . 0 4 39 . 0 8 9 2 1 7C JN 3 62 . 0 5 16, . 8 3 2 . 6 0 5 . 3 1 4 . 1 7 1 . 6 7 0 . 5 6 0 . 0 8 5 . 14 36 . 0 1 25 . 4 0 9 2 1 7D BL 4 6 3 . . 6 4 16 . 39 1 . 9 4 4 , . 5 7 4 . 2 0 7 2 . 132 0 . 4 7 8 0 . 0 7 4 4 . 2 1 2 . 0 2 1 . 9 7 3 0 . 73 18 . 0 3 9 2 1 70 BL 7 6 5 . , 8 9 15, . 7 9 1 . 7 6 4 . 4 1 4 . 275 2 . 2 1 4 0 . 4 7 0 0 . 0 7 1 3 . 8 9 1 . 6 5 2 . 0 6 31 . 6 3 19 . 9 3 9 2 1 7D BM 1 6 6 . . 26 16, . 3 3 1 . 73 4 , . 13 4 . 3 0 9 2 . 202 0 . 4 5 6 0 . 0 6 7 3 . 7 8 1 . 74 1 . 8 5 27 . 59 18 . 6 1 9 2 1 7D BM 2 67 . , 14 16 , . 6 8 1 . 2 1 4 . 17 4 . 8 2 4 1 . 2 8 1 0 . 3 8 0 0 . 0 6 8 3 . 0 0 1 . 4 4 1 . 4 0 26 . 8 0 17 62 9 2 1 70 BM 6 64 . 87 16 . 12 2 . 13 4 , . 27 3 . 9 1 2 2 . 3 8 3 0 . 563 0 . 0 7 1 4 . 4 1 2 . 0 5 2 . 13 32 . 8 9 27 , 85 9 2 1 7D J N 1 6 2 . 79 16 . 76 2 . 15 4 , . 8 6 4 . 3 5 2 . 9 7 0 . 5 3 0 . 0 8 4 . 52 32 . 9 5 2 3 , . 36 9 2 1 70 JN 7 6 5 . . 15 15 . 8 1 1 . 8 2 4 . 10 4 . 145 2 . 4 5 8 0 . 4 5 6 0 . 0 6 6 4 . 0 5 1 . 8 7 1 . 9 8 32 . 2 2 18 . 5 1 9 2 1 7D JN 9 6 6 . 5 8 15 . 9 4 1 . 7 6 4 . 0 3 4 . 4 1 3 2 . 4 6 5 0 . 4 16 0 . 0 7 1 3 . 73 1 . 8 5 1 . 6 7 31 . 2 1 24 . 0 8 9 2 1 7D JN 10 6 3 . 9 6 16 . 6 0 1 . 8 8 4 . 4 7 4 . 5 0 6 1 . 9 1 2 0 . 4 8 3 0 . 0 7 3 3 . 9 6 1 . 8 8 1 . 8 7 3 0 . 8 3 2 5 , . 23 9 2 1 7D JN 13 64 . 79 16 . 0 6 2 . 16 4 . 3 9 4 . 2 0 3 2 . 2 5 0 0 . 5 2 3 0 . 0 7 8 4 . 4 6 1 . 9 3 2 . 3 1 33 . 78 21 , . 26 9 2 1 7D JN 15 62 . 0 3 16 . 6 5 2 . 3 0 5 . 0 8 4 . 4 1 7 1 . 9 2 9 0 . 5 0 5 0 . 0 8 2 4 . 6 3 2 . 14 2 . 25 32 . 7 0 2 5 , . 26 9 2 1 7D JN 17 6 2 . . 9 8 16 . 79 1 . 7 9 4 , 8 8 4 . 2 7 1 . 9 0 0 . 4 8 0 . 0 6 4 . 3 0 34 , 9 1 23 , , 2 1 9 2 1 7D JN 18 62 . 5 3 17 . 25 2 . 37 4 . 9 0 4 . 5 1 2 . 10 0 . 6 4 0 . 0 7 4 . 72 34 , , 9 1 23 , . 2 1 9 2 1 7D JN 19 6 5 . . 12 15 . 24 1 . 85 3 . 9 3 3 . 9 5 5 2 . 6 7 9 0 . 5 2 9 0 . 0 6 3 4 . 26 1 . 9 3 2 . 12 3 5 , 10 2 5 . 13 9 2 1 7E BR 6 1 6 6 . 0 3 16 . 2 0 1 . 6 9 4 , . 2 9 4 . 142 2 . 2 1 2 0 . 4 6 6 0 . 0 6 9 3 . 8 9 32 , , 92 3 5 . . 46 9 2 1 7E BR 72 6 8 . . 0 4 14 , . 84 1 . 3 5 3 . 13 3 . 7 5 9 3 . 5 1 4 0 . 437 0 . 0 5 3 3 . 26 34 , . 7 3 34 . . 16 9 2 1 7E BR 73 6 3 . 5 4 16 . 0 0 2 . 2 2 4 . 5 5 4 . 105 2 . 5 1 7 0 . 553 0 . 0 7 4 4 . 55 3 3 , , 3 1 31 , 47 921 7E BR 75 6 5 . 1 1 16 . 0 9 1 . 78 4 . 4 2 4 . 162 2 . 2 0 4 0 . 574 0 . 0 6 5 4 . 36 32 , , 10 32 . 33 9 2 1 7E BR 76 6 6 . . 0 2 15 . 4 5 1 . 54 3 . 74 4 . 109 2 . 8 0 9 0 . 5 2 1 0 . 0 5 8 3 . 7 1 31 , . 56 3 3 . . 48 9 2 1 7E BR 77 6 4 . 25 15 . 8 9 1 . 8 9 4 . 4 5 4 . 0 8 6 2 . 5 8 5 0 . 532 0 . 0 6 7 4 . 15 34 . . 0 5 3 0 . 12 9 2 1 7E BR 7 9 6 1 , 7 2 16, . 6 2 2 . 0 8 5 . 10 4 . 3 3 6 1 . 8 8 7 0 . 5 5 0 0 . 0 6 9 4 . 6 8 34 . 43 32 . 36 9 2 1 7E BR 82 58 , , 8 8 15, . 94 1 . 73 4 . 78 4 .4 13 1 . 5 4 0 0 . 4 5 7 0 . 0 6 5 3 . 9 9 31 . 6 1 3 0 . 63 9 2 1 1 1A JN 2 6 2 . . 5 7 15, , 7 0 2 . 4 4 4 . . 6 5 4 . 1 12 2 . 294 0 . 5 6 5 0 . 0 8 5 4 . 7 1 2 , . 4 6 1 . 9 8 17 . 9 5 44 . 6 0 9 2 1 1 1A JN 5 6 2 . , 3 1 15 , 9 1 2 . 27 4 , , 64 4 . 2 6 1 1 . 9 2 0 0 . 5 0 9 0 . 0 8 2 4 . 4 5 2 . 17 2 . 0 4 2 0 , 94 44 . 0 3 9 2 1 1 1 A JN 6 5 8 , . 0 3 17 , . 67 2 . 9 0 6 . 0 3 4 . 3 3 0 1 . 5 2 5 0 . 6 3 4 0 . 0 9 2 5 . 6 1 2 . 7 8 2 . 5 2 21 . 0 3 44 . 34 9 2 1 1 1B BM 10 6 1 , . 24 16, . 7 1 2 . 7 2 4 . 9 8 4 . 0 0 8 2 . 0 4 7 0 . 6 2 1 0 . 0 8 1 5 . 0 6 2 . 7 3 2 . 0 3 16 . , 54 42 . 8 1 Bethlehem Phase NTS ID s i o 2 Al, 2°3 MgO 921 6H BR 87 66. 24 15 .66 1 .23 921 6H BR 101 65. 51 16 .37 1 .27 921 6H BR 1 16 66 . 53 16 .59 1 , . 12 921 6H BR 1 18 66. 05 16 .48 1 .04 921 6H JN 2 66. 42 17 .45 1 , .23 92110D BR 47 60. 41 16 .35 3 .07 921 1 1A BM 7 67 . 50 14 .90 0 .94 921 1 1A EG 17 66. 22 15 .25 1 , .70 921 1 1A JN 7 64 . 08 16 .27 1 , .45 CaO Na20 KjO T10 2 MnO Fe 2 0 3 FeO (tot) 4.23 4.759 1.866 0.383 0.056 3.30 4.55 5.005 1.544 0.362 0.071 3.26 4.45 4.960 1.476 0.377 0.066 3.12 4.42 5.050 1.515 0.341 0.054 2.98 4.70 4.98 1.39 0.37 0.07 3.47 5.17 3.972 2.415 0.706 0.096 5.74 2.31 4.09 2.95 0.23 0.13 2.42 3.77 3.960 2.773 0.503 0.062 3.86 1.97 4.27 4.727 1.690 0.407 0.073 3.55 1.56 Fe.0 o East North 18.87 40.52 18.72 32.72 24.85 36.26 25.69 37 . 19 19.42 31.67 29.31 49.59 25.39 43.05 1 .67 22.04 46.89 1.82 23 . 93 46.87 B e t h s a i d a Phase NTS ID S10 2 A l 2 0 3 MgO CaO NajO 921 6A JN 6 71 . 79 14 . ,88 0. .43 2 , .42 4 . 455 921 6A JN 8 70. 62 15. 89 0, .68 3 . 14 4 . 621 921 6H BM 2 67. 09 16. ,56 0. .66 3 .32 5.04 921 6H BR 88 70. 25 15. 38 0, ,50 2 .82 5 . 229 921 6H BR 92 69 . 60 16. , 17 0. ,65 3, .39 5. 103 921 6H BR 93 66 . 55 16. 53 1 . ,21 4 , 53 5 . 079 921 6H BR 95 70. ,21 15, ,64 0. .56 3 . 14 4 . 954 921 GH BR 96 69 . 18 15. . 34 0. ,65 3, .33 4 . 966 921 6H BR 97 70. ,23 15. .86 0. .58 3, .09 5. 181 921 6H BR 98 G9. ,00 15. , 19 0. 64 3. .28 4 . 822 921 6H BR 102 G9. 34 15. ,49 0. 69 3. . 26 4 . 889 921 6H BR 103 69 . .52 15. .71 0. 53 3 .23 5. 169 921 6H BR 104 71 , 64 15. ,81 0. .62 3 .54 5. 523 921 6H BR 108 68 . ,42 15. ,50 0. .62 3 .29 4 . 969 921 GH BR 109 69 . , 38 15. ,64 0. 62 3, .66 5. 397 921 6H BR 1 1 1 69 . . 10 15. ,23 0. 78 3, . 47 4 . 802 921 6H BR 1 12 70, .07 15 , 69 0. ,67 3 .27 4 . 863 921 6H BR 1 13 69, .88 15. ,49 0. ,62 3, . 17 4 . 794 921 6H BR 1 14 68 . 01 15. 99 0. ,66 3, .55 5 . 126 921 GH BR 120 69, .69 15. ,57 0. ,54 2 , .83 5. 248 921 6H BR 121 70, , 17 15. 21 6 . 48 2 , 68 5 . 301 921 6H BR 122 69 . ,59 16. , 13 0. 57 3 , .05 5. 202 921 6H BR 123 70 .08 15, .81 0. 50 2 .92 5. 278 921 6H BR 124 70 , 39 15, ,85 0. 49 2, .97 5 . 441 921 6H BR 125 70 .42 16 , 06 0. 51 2 , 82 5. 231 921 6H BR 126 68 .98 16. .00 0. 56 3. . 18 5. 354 921 6H JN 3 67 . 74 17 . 62 0. 66 3. 21 S i. 29 921 6H JN 4 67 . 29 18 .55 0. 73 3. .33 A I .66 921 6H JN 5 68 . 49 16, .44 0. 69 3. .63 4 . 764 921 7D BL 9 76 .04 13, .00 0. 12 0. .69 3 . 913 921 7D BL 10 76 .75 13, .04 0. , 12 0. .56 4 . 1 13 921 7D BL 1 1 75 . 78 13, . 56 0. 03 0. . 36 4 . 151 921 7D BL 13 70 .76 15 .96 0. ,70 3. .08 4 . 607 921 7D BL 15 77 . 13 13 .02 0. 10 0. . 57 3. 633 921 7E BM 3 77 .30 13 . 22 0. 05 0. .46 3 . 796 921 7E BM 4 70 .65 15, .65 0. 55 2. .60 4 . 359 921 7E BR 56 67 .85 16. .75 0. 88 3. .83 4 . 882 921 7E JN 1 69 .95 15 .52 0. ,64 2 . 95 4 . 478 921 7D BM 7 74 .45 14 .55 0. 28 1 . ,71 4 . 249 921 7E BL 1 75 . 45 13 . 36 0. 19 1 . ,37 3 I. 69 K 2 0 T10 2 MnO F e 2 0 3 FeO F e 2 0 3 East North (tot) 2 . 799 0. 138 0 .059 1 , .50 0. .65 0 .78 25 .34 23 .31 2 .089 0. 247 0 .063 2 . 24 0, .87 1 , .27 26 .53 25 .53 1 .72 0.26 0.06 2 .21 19 .45 36 .72 1 .935 0. 219 0 .04 1 1 .84 20 .03 40 .23 1 .984 0. 253 0 .067 2 , 19 19 .43 36 . 16 1 . 300 0. 374 0 .069 3 .31 18 .68 33 .99 2 .051 0. .217 0 .061 2 .06 19 .24 33 .99 1 .836 0. 244 0 .062 2 .20 21 .05 34 . 16 1 .807 0. 221 0 .050 1 , .97 19 .40 39 .01 2 .029 0. 230 0, .068 2 . 12 19 .54 32 .99 2 .075 0. 268 0 .064 2 , . 17 21 . 10 33 . 1 1 1 .675 0. .233 0 .057 2 .05 2 1 .85 35 .98 0. 282 0. 245 0 .050 1 .52 22 .33 35 .88 1.919 0. 232 0 .062 2 .01 22 .75 33 . 10 0.525 0. 228 0 .064 2 .21 24 . 84 31 . 15 1 .646 0. 288 0 .058 2 . 35 25 .92 30 .08 2 . 132 0. 256 0 .067 2 . 1 1 21 .81 30 .70 2. 196 0. 252 0 .064 2 . 18 22 . 45 30 .91 1 . 820 0. 265 0 .063 2 , .25 22 .97 34 , . 28 1 .853 0. 224 0 .04 1 1 , .90 21 .31 39, ,86 1 . 767 0. 217 0, .040 1 , . 76 22 . 42 39 85 1 .895 0. 259 0 .061 1 .96 21 .86 37 . 16 1 .841 0. 232 0 .058 1 , .84 22 .46 37 , 74 1 .575 0. 260 0, .053 1 , .86 22 . 24 38 , .41 1 .946 0. 238 0, .039 1 , . 76 2 1 , .41 38 . ,45 1 . 527 0. 248 0, .063 1 , .99 24 .69 32 . 74 0.66 0.26 0.08 2 , . 15 25 , .60 30. .66 1 .66 0. 28 0.06 2 . 35 25, . 16 29 . ,93 1 .874 0. 278 0. .058 2. .50 25 .69 29. .02 4.566 0. 078 0, .030 0. .78 0. 46 0. 26 28, .27 26. ,47 4 . 280 0. 075 0. .063 0. ,75 0. 26 0. 47 28 .63 26 . 06 4 .339 0. 052 0, ,021 0. 80 0. 14 0. 64 28, . 34 25 . ,77 2.181 0. 250 0, .060 2 . , 17 0. .94 1 . 12 27, .79 24 . , 79 4.625 0. 080 0. .023 0. ,88 0. .35 0. 49 29. .20 24 . , 10 4.396 0. 052 0, .009 0. ,57 29 , 54 28. 77 2.803 0. 21 1 0. ,055 1. ,70 29, ,57 28 . 57 1 .864 0. 282 0. 036 2 . 65 28. ,65 35. 95 2 .568 0. 213 0. 051 2 . 1 1 0. 96 1 . 05 27, .00 28 . 75 3.261 0. 1 15 0. ,044 1 . 03 0. 44 0. 54 30. ,08 27 . 71 3.60 0. 10 0.02 0. 92 30. 21 31 . 44 150 GUICHON CREEK BATHOLITH • BORDER PHASE o GUICHON VANETY • CHATAWAY VARCTY ° BETHLEHEM PHASE • BETHSAOA PHASE MNE PWOPCBTY LX LORNEX PROPERTY VC VALLEY COPPER PROPERTY JA JA DEPOSIT BE BETHLEHEM PROPERTY HT KK3HMONT PROPERTY HIGHLAND VALLEY PHASE APPENDIX(D): SAMPLE LOCATION MAP-

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