UBC Theses and Dissertations

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UBC Theses and Dissertations

Isotopic identification of subglacial processes Maxwell, Michael 1986

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ISOTOPIC IDENTIFICATION OF SUBGLACIAL PROCESSES by MICHAEL MAXWELL B . S c , R o y a l M i l i t a r y C o l l e g e of Canada, 1976 M.A., U n i v e r s i t y o f Ottawa, 1979 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES De p a r t m e n t o f G e o p h y s i c s and Astronomy We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA 1986 © MICHAEL MAXWELL, 1986 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e The U n i v e r s i t y of B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my Department o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e partment o f G e o p h y s i c s and A s t r o n o m y The 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 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 D a t e : 1986 DEDICATION E l l e l i t son c o e u r . i i ABSTRACT A c o m p r e h e n s i v e s t a b l e i s o t o p e s t u d y of b a s a l i c e and d e b r i s l a y e r s i n two Yukon s u r g i n g g l a c i e r s s u g g e s t s an i s o t o p i c a l l y v a r i a b l e b a s a l f r e e z i n g c y c l e . T r a p r i d g e and Backe G l a c i e r s , S t . E l i a s Range, Yukon, Canada, have p a r a l l e l b a s a l d e b r i s l a y e r s t h a t e x t e n d f o r h u n d r e d s o f m e t r e s a l o n g m a r g i n a l i c e f a c e s and i n m e l t w a t e r t u n n e l s . The i s o t o p i c c o m p o s i t i o n s o f s a m p l e s a t 1-5 cm i n t e r v a l s from v e r t i c a l i c e c o r e s i n b a s a l i c e e x p o s u r e s , have t h e f o l l o w i n g c h a r a c t e r i s t i c s : 1. The 5 0 1 8 and 5D v a l u e s o f i c e i m m e d i a t e l y above a d e b r i s l a y e r a r e h i g h e r t h a n t h e v a l u e s i m m e d i a t e l y below a d e b r i s l a y e r (up t o 3 ° / 0 0 ) . 2. The 6 0 1 8 and 6D v a l u e s v a r y between d e b r i s l a y e r s . The most common t r e n d i s an i n c r e a s e i n 5 0 1 8 and 5D w i t h d e c r e a s i n g h e i g h t above t h e bed. 3. C l e a r i c e l a y e r s , w h i c h a r e f r e q u e n t l y i m m e d i a t e l y above d e b r i s l a y e r s , have h i g h e r 5 0 1 8 and 6D v a l u e s t h a n s u r r o u n d i n g i c e . 4. A c r o s s c o r e l e n g t h s o f 0.5-2.2 m, t h e r e i s no s i g n i f i c a n t o v e r a l l i s o t o p i c s h i f t f r o m t o p t o b o t t o m of a c o r e . A l o n g a 100 m l o n g i t u d i n a l t u n n e l , t h e r e i s no s i g n i f i c a n t i s o t o p i c change i n t h e a v e r a g e o f s a m p l i n g s a t t h e e n t r a n c e , m i d d l e and e x i t of t h e t u n n e l . T r a p r i d g e and Backe G l a c i e r s a r e s u b p o l a r s u r g i n g g l a c i e r s t h a t s u r g e on a c y c l e o f 40-50 y e a r s . They a r e a p p r o x i m a t e l y 5 km l o n g and 1 km wide w i t h a l o w e r a b l a t i o n zone t h a t i s f r o z e n t o t h e bed and an u p p e r a c c u m u l a t i o n zone t h a t has b a s a l i c e a t t h e p r e s s u r e m e l t i n g t e m p e r a t u r e . The b a s a l i c e i s c o m p r i s e d o f p a r a l l e l d e b r i s l a y e r s r a n g i n g f r o m l e s s t h a n 1 cm t o 40 cm i n t h i c k n e s s , and i c e l a y e r s from l e s s t h a n 1 cm t o 70 cm i n t h i c k n e s s . The d e b r i s s e q u e n c e s a r e 5-25 m t h i c k , a c c o u n t i n g f o r up t o one h a l f o f t h e g l a c i e r d e p t h s i n t h e a b l a t i n g i c e z o n e s . M i c r o p a r t i c l e and c a t i o n c o n c e n t r a t i o n s a r e much h i g h e r i n b a s a l i c e t h a n i n b u l k ( p r e c i p i t a t e d ) i c e . The i s o t o p i c , c h e m i c a l , m i c r o p a r t i c l e , and l a y e r c h a r a c t e r i s t i c s o f t h e d e b r i s s e q u e n c e s do not s u g g e s t a s h e a r i n g mechanism o f i n c o r p o r a t i o n . I p r o p o s e a c c r e t i o n by a b a s a l f r e e z i n g p r o c e s s w h i c h i s i s o t o p i c a l l y v a r i a b l e . I n c o r p o r a t i o n of a d e b r i s l a y e r i s a s s o c i a t e d w i t h a change i n c o m p o s i t i o n of t h e w a t e r s u p p l y o r a change i n t h e f r e e z i n g mechanism, t h e r e b y c a u s i n g an i s o t o p i c s h i f t . The d e g r e e of f r a c t i o n a t i o n d u r i n g b a s a l a c c r e t i o n w i l l be a f f e c t e d by f r e e z i n g r a t e s and m i x i n g i n t h e w a t e r r e s e r v o i r . An a n n u a l i s o t o p i c c o m p o s i t i o n c y c l e i n b a s a l w a ter c a u s e d by m i x i n g w i t h s u r f a c e w a t e r , o r an a n n u a l f r e e z i n g r a t e c y c l e c a u s e d by v a r i a b l e b a s a l w a t e r s u p p l y and h e a t f l o w , c a n p r o d u c e t h e i s o t o p i c v a r i a t i o n s between d e b r i s l a y e r s . In a d d i t i o n , i c e s e g r e g a t i o n p r o c e s s e s s u c h as p r i m a r y and s e c o n d a r y h e a v i n g may a f f e c t t h e f r a c t i o n a t i o n p r o c e s s , p a r t i c u l a r l y d u r i n g i c e s e g r e g a t i o n f r o m a s e d i m e n t s u b s t r a t e . Heavy i s o t o p e r e l a t i o n s h i p s between 5D and 6 0 1 8 were u s e d t o examine t h e b a s a l f r e e z i n g f r a c t i o n a t i o n mechanism. The 5D and 6 0 1 8 r e l a t i o n s h i p s had s t r a i g h t l i n e a p p r o x i m a t i o n s w i t h s l o p e s 7.53 ±0.39 and 6.75 ±0.28 f o r T r a p r i d g e G l a c i e r _ b u l k and b a s a l i v i c e r e s p e c t i v e l y , and 7.31 ±0.13 and 6.27 ±0.17 f o r Backe G l a c i e r b u l k and b a s a l i c e . A m a j o r i t y o f samples ( a l l but 5 o f 200 s a m p l e s ) p l o t t e d t o t h e r i g h t o f t h e m e t e o r i c l i n e of s l o p e 8.04 ±0.34 t h a t was d e t e r m i n e d i n t h i s s t u d y . The b u l k i c e has been i s o t o p i c a l l y a l t e r r e d d u r i n g snow e v o l u t i o n p r o c e s s e s s u c h a s p e r c o l a t i o n e x c h a n g e . Backe and T r a p r i d g e G l a c i e r s c o n s i s t o f s i g n i f i c a n t p r o p o r t i o n s of s u p e r i m p o s e d i c e , s u g g e s t i n g t h a t t h e b u l k i c e s l o p e r e p r e s e n t s i s o t o p i c s h i f t s i n snow w i t h a r a n g e of i n i t i a l i s o t o p i c c o m p o s i t i o n s , r a t h e r t h a n i s o t o p i c e v o l u t i o n a l o n g t h e b u l k s l o p e l i n e . The i s o t o p i c c o m p o s i t i o n o f t h e b a s a l w a ter s u p p l y d u r i n g b a s a l f r e e z i n g d e t e r m i n e s t h e s i g n i f i c a n c e o f t h e b a s a l i c e s l o p e . S p a t i a l o r t i m e v a r i a b l e b a s a l i s o t o p i c c o m p o s i t i o n s i m p l y t h a t t h e b a s a l i c e s l o p e r e p r e s e n t s s a m p l e s t h a t have been s h i f t e d from a r a n g e of o r i g i n a l c o m p o s i t i o n s a l s o , r a t h e r t h a n a t i m e - e v o l v i n g f r a c t i o n a t i o n f r o m an a v e r a g e b a s a l i s o t o p i c r e s e r v o i r . The h y p o t h e s i s of a b a s a l a c c r e t i o n p r o c e s s w i t h d e p e n d e n c e upon m i x i n g and v a r i a b l e f r e e z i n g r a t e s d i s c o u r a g e s t h e use of t h e heavy i s o t o p e s l o p e a s an i n d i c a t o r of a s i n g l e b a s a l f r a c t i o n a t i o n p r o c e s s ( i . e . c o n s t a n t f r a c t i o n a t i o n f r o m an i s o t o p i c a l l y c o n s t a n t r e s e r v o i r ) . The heavy i s o t o p e r e l a t i o n s h i p may s t i l l be u s e f u l t o i d e n t i f y b u l k and b a s a l i c e i n a g l a c i e r where d i f f e r e n c e s i n s l o p e have been c h a r a c t e r i z e d . v T a b l e o f C o n t e n t s DEDICATION i i ABSTRACT i i i TABLE OF CONTENTS v i L I S T OF FIGURES v i i i L I S T OF TABLES i x ACKNOWLEDGEMENTS X 1. INTRODUCTION 1 1 . 1 The P r o b l e m 1 1.2 S u r g i n g G l a c i e r s 6 1.2.1 The S t u d y A r e a 8 1 . 3 I s o t o p e s 10 1.3.1 M e t e o r i c P r o c e s s e s 19 1.3.2 Snow/Ice E v o l u t i o n 20 1.3.2.1 E v a p o r a t i o n / S u b l i m a t i o n F r a c t i o n a t i o n s .20 1.3.2.2 M e l t / F r e e z e F r a c t i o n a t i o n s 21 1.3.3 G e o c h e m i c a l F r a c t i o n a t i o n 24 1.3.4 B u l k I c e E v o l u t i o n 26 1.3.5 B a s a l I c e E v o l u t i o n 28 1.3.5.1 M i x i n g P r o c e s s e s 28 1.3.5.2 F r e e z i n g P r o c e s s e s 29 1 . 4 Summary 32 2. METHODS 35 2.1 F i e l d w o r k 35 2.2 Oxygen I s o t o p e s 39 2.3 H y d r o g e n I s o t o p e s 41 2.4 S l o p e C a l c u l a t i o n s 42 3. RESULTS 44 v i 3.1 G e n e r a l O b s e r v a t i o n s 44 3.2 S i t e R e s u l t s 51 3.2.1 TRST8 51 3.2.2 TRB2 51 3.2.3 TRC1 56 3.2.4 TRC2 56 3.2.5 BA 1 61 3.2.6 BA2 .61 3.3 Heavy I s o t o p e R e l a t i o n s h i p 64 3.3.1 M e t e o r i c R e s u l t s 64 3.3.2 B u l k I c e 67 3.3.3 B a s a l I c e 70 3.4 Water Q u a l i t y and Sediment A n a l y s e s 73 4. DISCUSSION 78 4.1 I n t e r p r e t a t i o n o f R e s u l t s 78 4.2 S u b g l a c i a l I s o t o p i c P r o c e s s e s 82 4.2.1 M i x i n g P r o c e s s e s : B a s a l Water S u p p l y 82 4.2.2 F r e e z i n g R a t e s 85 4.2.3 F r e e z i n g P r o c e s s e s 86 4.2.3.1 D i r e c t F r e e z i n g 87 4.2.3.2 P r i m a r y and S e c o n d a r y H e a v i n g 87 4.3 D e b r i s E n t r a i n m e n t and I c e A c c r e t i o n 90 5. CONCLUSIONS 103 5.1 The F u t u r e 1 06 REFERENCES 109 APPENDIX 1. RESULTS OF ISOTOPIC ANALYSES 116 APPENDIX 2. SECONDARY HEAVING MODEL 127 v i i L i s t o f F i g u r e s 1. T y p i c a l b a s a l d e b r i s s e q u e n c e 3 2. C h a r a c t e r i s t i c s o f a t y p i c a l d e b r i s s e q u e n c e 5 3. S u r g i n g G l a c i e r s o f t h e Mt S t e e l e A r e a , Yukon, Canada ....9 4. Summary o f T r a p r i d g e measurements from 1969-1981 1 1 5. T e m p e r a t u r e p r o f i l e s f o r T r a p r i d g e G l a c i e r 13 6. Water e v o l u t i o n i n a g l a c i a l s y s t e m 15 7. Water f r a c t i o n a t i o n i n a g l a c i a l s y s t e m 34 8. Sample s i t e s on T r a p r i d g e and Backe G l a c i e r s 37 9. TR81 i s o t o p i c s u r f a c e p r o f i l e 46 10. TR81 heavy i s o t o p e r e l a t i o n s h i p 48 11. TRST8 i s o t o p i c s t r a t i g r a p h y 52 12. TRST8 heavy i s o t o p e r e l a t i o n s h i p 53 13. TRB2 i s o t o p i c s t r a t i g r a p h y 54 14. TRB2 heavy i s o t o p e r e l a t i o n s h i p 55 15. TRC1 i s o t o p i c s t r a t i g r a p h y 57 16. TRC1 heavy i s o t o p e r e l a t i o n s h i p 58 17. TRC2 i s o t o p i c s t r a t i g r a p h y 59 18. TRC2 heavy i s o t o p e r e l a t i o n s h i p 60 19. BA1 i s o t o p i c s t r a t i g r a p h y 62 20. BA2 i s o t o p i c s t r a t i g r a p h y 65 21. T r a p r i d g e G l a c i e r b u l k heavy i s o t o p e r e l a t i o n s h i p 66 22. Backe G l a c i e r b u l k heavy i s o t o p e r e l a t i o n s h i p 69 23. T r a p r i d g e G l a c i e r b a s a l heavy i s o t o p e r e l a t i o n s h i p 71 24. Backe G l a c i e r b a s a l heavy i s o t o p e r e l a t i o n s h i p 72 25. T y p i c a l g r a i n s i z e d i s t r i b u t i o n i n d e b r i s l a y e r s 74 26. M i c r o p a r t i c l e c o n c e n t r a t i o n s i n b u l k and b a s a l i c e 75 27. D e b r i s i n c o r p o r a t i o n by f r e e z i n g p l a n e advancement 97 28. D e b r i s i n c o r p o r a t i o n by s e c o n d a r y h e a v i n g 98 v i i i L i s t o f T a b l e s 1. P r o p e r t i e s o f i s o t o p i c w ater s p e c i e s 17 2. S e d i m e n t c o n c e n t r a t i o n s i n d e b r i s l a y e r s 73 3. M a j o r i o n c o n c e n t r a t i o n s i n T r a p r i d g e i c e 77 4. S l o p e s f r o m J o u z e l and Souchez models 80 5. T h e r m a l c a l c u l a t i o n s f o r T r a p r i d g e G l a c i e r 92 A1.1. I s o t o p i c r e s u l t s f o r TRST8 ...117 A1.2. I s o t o p i c r e s u l t s f o r TRB1 118 A1.3. I s o t o p i c r e s u l t s f o r TRB2 119 A1.4. I s o t o p i c r e s u l t s f o r TRC1 120 A1.5. I s o t o p i c r e s u l t s f o r TRC2 121 A1.6. I s o t o p i c r e s u l t s f o r BA1 122 A1.7. I s o t o p i c r e s u l t s f o r BA2 125 A2.1. R e s u l t s of s e c o n d a r y h e a v i n g a f t e r one y e a r 129 i x ACKNOWLEDGEMENTS I s a v e d t h i s acknowledgement s e c t i o n u n t i l t h e end, p a r t l y t o s a v o u r t h e c o m p l e t i o n o f t h e w r i t i n g ( h o p e f u l l y ) , b u t m a i n l y t o a l l o w me a c h a n c e t o r e f l e c t on t h e p e o p l e t h a t have c o n t r i b u t e d t o t h i s t h e s i s and my l i f e . In a s t u d y w i t h t h i s amount of l a b work and o f t h i s d u r a t i o n , t h e r e a r e many p e o p l e t h a t have p r o v i d e d h e l p , a d v i c e , f a c i l i t i e s , and t i m e . I n e v i t a b l y I w i l l f o r g e t someone, and my f i r s t t h a n k s i s t o any f o r g o t t e n o n e s . I was a b l y s u p p o r t e d i n my t h e f i e l d w o r k by a s u c c e s s i o n of d e d i c a t e d f i l e d a s s i s t a n t s . I thank E m i l y C h a s e , A l i s o n H a r t , Rob O r v i g , J e f f Schmok, D a v i d W a l d r o n , and D a v i d W i l l i a m s . P a r k s Canada g r a n t e d p e r m i s s i o n t o c a r r y o ut r e s e a r c h i n K l u a n e N a t i o n a l P a r k and t h e A r c t i c I n s t i t u t e of N o r t h A m e r i c a K l u a n e R e s e a r c h S t a t i o n ( U n i v e r s i t y o f C a l g a r y ) p r o v i d e d a home away from home t o s t a g e t h e f i e l d t r i p s f r o m . Thanks a g a i n t o Andy and C a r o l W i l l i a m s , C l a u d e t t e and t h e l a t e P h i l U p t o n , and t h e r e s t of t h e K l u a n e gang f o r f u n and f r u i t f u l d i s c u s s i o n s . F i n a l l y , t h e a b l e p i l o t s o f T r a n s N o r t h T u r b o A i r , p a r t i c u l a r l y R i c h W a r s o f s k y , a r e t o be c o n g r a t u l a t e d f o r k e e p i n g me a l i v e and making t h e e x c i t i n g p r o c e s s o f h e l i c o p t e r t r a n s p o r t a t i o n , t h e r o u t i n e p r o c e d u r e t h a t i t c a n be. The l a b o r a t o r y component r e q u i r e d t h e g e n e r o s i t y o f many g r o u p s . The oxygen i s o t o p e a n a l y s e s were c o m p l e t e d i n t h e l a b o r a t o r y o f t h e G e o p h y s i c a l I n s t r u m e n t a t i o n G roup a t UBC and I am g r a t e f u l t o Don R u s s e l l , P e t e r W h a i t e and B a r r y N a r o d f o r t h e i r a s s i s t a n c e and a d v i c e . The h y d r o g e n a n a l y s e s were c o m p l e t e d x i n t h e Mass S p e c t r o m e t e r L a b o r a t o r y of t h e D e p a r t m e n t of P h y s i c s a t U n i v e r s i t y of A l b e r t a . I thank D r . John G r a y f o r h i s open o f f e r t h a t a l l o w e d me c o m p l e t e a c c e s s t o t h e f a c i l i t i e s of h i s l a b o r a t o r y . I a l s o t h ank Len T o b e r , Chas Yonge, J a m i e Freeman and Changka f o r t h e i r a d v i c e and a s s i s t a n c e . The UBC Geography S e d i m e n t L a b o r a t o r y f a c i l i t i e s were p r o v i d e d by D r s . M i k e B o v i s and M i k e C h u r c h and I a p p r e c i a t e t h e i r h e l p . The F o r e s t F i r e S c i e n c e L a b o r a t o r y of D r . Mike F e l l e r a n a l y z e d t h e water c h e m i s t r y w h i c h p r o v i d e d some i c i n g on t h e c a k e . Thank-you t o B r u c e B l a c k w e l l . I a l s o a p p r e c i a t e a s s i s t a n c e f r o m NWRI V a n c o u v e r and C h r i s P h a r o and V i v i a n f o r t h e i r h e l p d u r i n g t h e s e d i m e n t a n a l y s e s . M i c r o p a r t i c l e c o n c e n t r a t i o n s were measured i n D r . P . J . H a r r i s o n ' s l a b o r a t o r y i n t h e Department o f O c e a n o g r a p h y . I a p p r e c i a t e t h e a s s i s t a n c e o f P e t e r Thompson i n t h e c o m p l e t i o n of t h e work. L i f e i n t h e D e p a r t m e n t o f G e o p h y s i c s and A s t r o n omy has p r o v i d e immense b e n e f i t s t o my d e v e l o p m e n t ; t h e s p i k e s o f H a r v e y and G r e g , t h e p a t i e n c e o f Doug, t h e C h r i s t m a s p a r t i e s , t h e h i g h f i v e e x p l o i t s of t h e G e o p h y s i c s b a s k e t b a l l team, hamburger s p e c i a l s a t t h e w e l l - n a m e d P i t , t h e i n f i n i t e knowledge o f Ed, P e t e r and B a r r y , t h e l a t e n i g h t two-ended c a n d l e - b u r n e r s and t h e t h o u s a n d s o f a n s w e r s t o q u e s t i o n s , good, bad and u g l y . Thanks t o B r a d P r a g e r f o r a l l of t h e computer h e l p and s t e a l i n g t h e c o l d o f f i c e , and t o IT&A f o r q u a l i t y p l o t t i n g . I p a r t i c u l a r l y s i n g l e - o u t t h e knowledge, a s s i s t a n c e and p a t i e n c e o f t h e t e c h n i c i a n s and o f f i c e s t a f f who made l i f e e a s i e r i n many ways — Mary, Sue, L y d i a , Donna, J u d y , D i e t e r , B i l l , H a r r y and P e t e r . x i Thanks t o them and t o a l l of t h e f a c u l t y and s t u d e n t s . My c o m m i t t e e members p r o v i d e d me w i t h d i r e c t i o n and i n c e n t i v e s t o f o r g e a h e a d i n t o t h e unknown and I am g r a t e f u l f o r t h e i r h e l p — D r s . R . J . Mackay, R.D. R u s s e l l , T . J . U l r y c h and R.M. E l l i s i n t h e f i n a l p i n c h . The i n s p i r a t i o n o f t h a t c omic book h e r o , GLACIER MAN, a t t r a c t e d me f r o m t h e s n o w f i e l d s of Canada t o p u t r e s e a r c h i n t o t h e more c o m p a c t e d f o r m . G a r r y C l a r k e has been an i n s p i r a t i o n and a delight to work under and I a p p r e c i a t e h i s e n c o u r a g e m e n t and example. He p r o v i d e d me w i t h t h e r e l a x e d e n v i r o n m e n t w h i c h p e r m i t t e d me t o make my own a d v a n c e s and my own m i s t a k e s , t h e b e s t way t o l e a r n . The Yukon p r o v i d e d me w i t h t h e g r e a t e s t i n s p i r a t i o n s p o s s i b l e , t h e a l l u r e o f t h e N o r t h e r n sky and t h e r o m a n t i c s e t t i n g t o make even a g e o p h y s i c i s t l o o k g r e a t . B e d a z z l e d she was, and she c o n t i n u e s t o d a z z l e me. A l i s o n i n s p i r e d and i n s p i r e s me t o a c h i e v e t h e b e s t i n e v e r y t h i n g and I thank h e r f o r a l o t and f o r e v e r . x i i C h a p t e r 1 INTRODUCTION In s p i t e o f t h e i r c r i t i c a l r o l e i n t h e e v o l u t i o n o f t h e g l a c i a l e n v i r o n m e n t , complex i n t e r a c t i o n s a t g l a c i e r / b e d i n t e r f a c e s a r e r a r e l y o b s e r v e d and p o o r l y u n d e r s t o o d . From a n a l y s e s o f b a s a l i c e and d e b r i s c h a r a c t e r i s t i c s o f two s u r g i n g g l a c i e r s , I p r o p o s e mechanisms o f i c e and d e b r i s i n c o r p o r a t i o n a t s u r g i n g g l a c i e r b eds, w h i c h can a s s i s t i n i n t e r p r e t i n g mechanisms a c t i v e a t a l l g l a c i e r b e d s . The two s u r g i n g g l a c i e r s a r e c h a r a c t e r i z e d by e x t e n s i v e d e b r i s l a y e r e x p o s u r e s a l o n g l a t e r a l and t e r m i n a l m a r g i n s . The i s o t o p i c , f a b r i c , and c h e m i c a l p r o p e r t i e s of t h e i c e and d e b r i s s u g g e s t t h a t i c e s e g r e g a t i o n from a s u b g l a c i a l w a t e r s y s t e m forms t h e b a s a l l a y e r s . The m a j o r c o n t r i b u t i o n s of t h i s t h e s i s a r e : 1. C h a r a c t e r i z a t i o n of i s o t o p i c and c h e m i c a l p r o p e r t i e s o f b a s a l and b u l k i c e i n two s u r g i n g g l a c i e r s . 1 2. I d e n t i f i c a t i o n o f i s o t o p i c f r a c t i o n a t i o n d u r i n g b u l k i c e f o r m a t i o n f r o m m e t e o r i c w a t e r s . 3. C h a r a c t e r i z a t i o n of i s o t o p i c v a r i a t i o n s i n b a s a l i c e . 4. A s s o c i a t i o n o f t h e s e i s o t o p i c e f f e c t s w i t h b a s a l f r e e z i n g p r o c e s s e s . 1.1 THE PROBLEM In many p o l a r and s u b p o l a r g l a c i e r s e x t e n s i v e i n t e r b e d d e d d e b r i s a n d i c e l a y e r s a r e e x p o s e d ; t h e s e l a y e r s a r e a p p r o x i m a t e l y p a r a l l e l t o t h e bed and e x t e n d f o r h u n d r e d s o f m e t r e s a l o n g 1 B u l k i c e i s formed a t o r nea r t h e s u r f a c e o f a g l a c i e r ; b a s a l i c e i s f o r m e d a t o r n e a r t h e bed. 1 2 g l a c i e r m a r g i n s ( s e e B o u l t o n 1972 and F i g u r e s 1 and 2 ) . Two g e n e r a l t h e o r i e s have been s u g g e s t e d t o e x p l a i n t h e e n t r a i n m e n t o f i c e and d e b r i s a t g l a c i e r b e d s : t h r u s t i n g ( G o l d t h w a i t 1951; B i s h o p 1957) and b a s a l f r e e z i n g (Weertman 1961; B o u l t o n 1970, 1983). T h r u s t i n g e n t r a i n s d e b r i s a l o n g b a s a l s h e a r z o n e s , p o s s i b l y by i n j e c t i o n o f l i q u i d i z e d s u b s t r a t e . B a s a l f r e e z i n g i s p o s t u l a t e d t o i n c o r p o r a t e s e d i m e n t by c y c l i c a l s h i f t s i n b a s a l z o n e s o f m e l t i n g and f r e e z i n g (Weertman 1961), i n z o n e s w i t h h y d r o l o g i c a l and t h e r m a l c o n d i t i o n s t h a t c a u s e m i g r a t i o n of t h e f r e e z i n g p l a n e i n t o t h e s u b s t r a t e ( B o u l t o n 1970, 1972, 1979, 1983), o r by i n t r u s i o n of b a s a l i c e i n t o t h e s e d i m e n t by r e g e l a t i o n a n d / o r d e f o r m a t i o n ( J . W a l d e r , B. H a l l e t - p e r s o n a l c o m m u n i c a t i o n ) . B a s a l f r e e z i n g i s more l i k e l y t o p r o d u c e e x t e n s i v e d e b r i s l a y e r s , but t h e p r e s e n t t h e o r y i s i n a d e q u a t e f o r e x p l a i n i n g t h e i n c o r p o r a t i o n o f r e g u l a r and e x t e n s i v e a l t e r n a t i n g s e q u e n c e s o f d e b r i s and i c e . T r a p r i d g e and Backe G l a c i e r s a r e p o s t u l a t e d t o have s e d i m e n t s e d i m e n t s u b s t r a t e s . M a s s i v e g r o u n d i c e e x p o s u r e s w i t h i n t e r b e d d e d s e d i m e n t l a y e r s have c h a r a c t e r i s t i c s s i m i l a r t o t h e t h i c k b a s a l d e b r i s s e q u e n c e s i n t h e s e g l a c i e r s (Mackay 1971, 1973). In g r o u n d i c e , t h e i n t e r b e d d e d i c e and d e b r i s l a y e r s a r e p o s t u l a t e d t o d e v e l o p by ice segregation t h r o u g h c y c l i c a l i c e l e n s i n g i n t h e s o i l . I c e s e g r e g a t i o n i s a g e n e r a l t e r m u s e d t o d e s c r i b e f r e e z i n g of w ater i n t o d i s c r e t e i c e l e n s e s r a t h e r t han i n s i t u f r e e z i n g i n s o i l p o r e s , i . e . c a p i l l a r y o r a d s o r b e d f o r c e s c a n c a u s e f l o w o f w ater t o an i c e l e n s . In p e r m e a b l e s u b s t r a t e s , a p r o c e s s o f i c e s e g r e g a t i o n may i n c o r p o r a t e i c e and d e b r i s a t a 3 F i g u r e 1. T y p i c a l b a s a l d e b r i s s e q u e n c e . The p i c t u r e was t a k e n i n a m e l t w a t e r t u n n e l t h r o u g h a s e c t i o n o f s t a g n a n t T r a p r i d g e G l a c i e r i c e ( p h o t o g r a p h by J . Schmok). 5 F i g u r e 2. C h a r a c t e r i s t i c s o f a t y p i c a l d e b r i s s e q u e n c e . The 6 0 1 8 s t r a t i g r a p h y o f t h i s c o r e f r o m t h e Backe G l a c i e r i c e f a c e i s d e s c r i b e d i n S e c t i o n 3.2.6 and F i g u r e 20. The c o n n e c t e d b a r s g i v e t h e 6 0 i a o f a l a y e r sampled i n t h e f i e l d and t h e d i s c o n n e c t e d b a r s g i v e t h e r e s u l t s of l a y e r s from c o r e s which were r e t u r n e d t o a c o l d room and sampled (5D r e s u l t s p a r a l l e l t h e oxygen r e s u l t s ) . The s h a d e d i c e t y p e s a r e d e s c r i b e d i n S e c t i o n 3.1. The u n c e r t a i n t i e s a r e n o t shown on t h e g r a p h , but a r e r e p r e s e n t e d by t h e 1o e r r o r b a r s on t h e l o w e r r i g h t . The l e n g t h o f a l i n e i n d i c a t e s t h e t h i c k n e s s o f a sample l a y e r BACKE ICE FACE 2 6 0 1 0 a.) 6 g l a c i e r b e d . By c o m p a r i n g p r o p e r t i e s o f b a s a l and b u l k i c e , t h e mechanisms o f b a s a l d e b r i s and i c e a c c r e t i o n may be i d e n t i f i e d . B u l k i c e has been d i s t i n g u i s h e d from b a s a l i c e by a n a l y z i n g h y d r o g e n and oxygen i s o t o p e s (Lawson and K u l l a 1978; J o u z e l and S o u c h e z 1982), water c h e m i s t r y , and i c e and d e b r i s f a b r i c s ( H a l l e t e t a l . 1978; S o uchez and L o r r a i n 1978; B o u l t o n 1983). W i t h an a s s o c i a t e d a n a l y s i s of b u l k and b a s a l i c e p r o p e r t i e s , p r o c e s s e s o f b a s a l a c c r e t i o n may be i d e n t i f i e d by d e v e l o p i n g a c o n t i n u o u s i s o t o p i c s t r a t i g r a p h y o f t h e b a s a l i c e l a y e r s . In a d d i t i o n , a s t u d y of r e l a t i o n s h i p s between h y d r o g e n and oxygen i s o t o p e s i n t h e b a s a l l a y e r s c a n a s s i s t i n i n t e r p r e t i n g a c c r e t i o n mechanisms. I have u s e d t h e s e t e c h n i q u e s i n a s t u d y o f two Yukon s u r g i n g g l a c i e r s , T r a p r i d g e and Backe G l a c i e r s , t o h y p o t h e s i z e b a s a l p r o c e s s e s . 1.2 SURGING GLACIERS S u r g i n g g l a c i e r s have f l o w c y c l e s t h a t c o n s i s t of a q u i e s c e n t phase c h a r a c t e r i z e d by slow v e l o c i t i e s ( e . g . 25 m a " 1 f o r T r a p r i d g e G l a c i e r , Y u k o n ) , and an a c t i v e p h a s e c h a r a c t e r i z e d by f a s t v e l o c i t i e s ( e . g . 1 o r 2 km a " 1 f o r T r a p r i d g e G l a c i e r ) . M e i e r and P o s t (1969) i d e n t i f i e d t h e f o l l o w i n g c h a r a c t e r i s t i c s f o r s u r g e - t y p e g l a c i e r s : 1. C y c l e s v a r y i n g f r o m 15 t o 100 y e a r s and g r e a t e r . 2. I n s t a n t a n e o u s s u r g e v e l o c i t i e s from 150 m a " 1 t o 6 km a " 1 and g r e a t e r . 3. D i s p l a c e m e n t s from a p p r o x i m a t e l y 1 km t o 11 km and g r e a t e r i n 1 o r 2 y e a r s . 7 Temp e r a t e s u r g i n g g l a c i e r s a r e a t t h e p r e s s u r e m e l t i n g t e m p e r a t u r e t h r o u g h o u t ( B i n d s c h a d l e r e t a l . 1976; Kamb e t a l . 1985), whereas s u b p o l a r s u r g i n g g l a c i e r s a r e c h a r a c t e r i z e d by an upper zone t h a t h as b a s a l i c e a t t h e p r e s s u r e m e l t i n g t e m p e r a t u r e and a l o w e r zone t h a t i s f r o z e n t o t h e bed ( C l a s s e n and C l a r k e 1972; C l a r k e e t a l . 1984). A b u l g e c a n f o r m when t h e h i g h e r v e l o c i t y i c e i s dammed by t h e n o n - s l i d i n g l o w e r zone ( C l a r k e e t a l . 1984; Kamb e t a l . 1985). T h e r m a l i n s t a b i l i t i e s ( C l a r k e 1976) and p o n d i n g o f w a t e r , due t o a s h e a r s t r e s s g r a d i e n t ( R o b i n and Weertman 1973) o r a f r o z e n o r low p e r m e a b i l i t y l a y e r , have been p r o p o s e d a s s u r g e mechanisms, b u t r e c e n t s t u d i e s have i d e n t i f i e d b a s a l w ater c i r c u l a t i o n a s t h e c r i t i c a l f a c t o r ( C l a r k e e t a l . 1984; Kamb e t a l . 1985). From o b s e r v a t i o n s of t h e r e l a t i o n s h i p between b a s a l w a t e r p r e s s u r e s and s u r g e v e l o c i t i e s o f V a r i e g a t e d G l a c i e r , Kamb e t a l . (1985) p r o p o s e d t h a t c a v i t a t i o n c r e a t e s an i n t e r c o n n e c t e d s u b g l a c i a l w a t e r s y s t e m h a v i n g a v a r i a b l e c a p a c i t y . When t h e wat e r i n p u t becomes g r e a t e r t h a n t h e c a p a c i t y , f l o t a t i o n o f t h e g l a c i e r c a u s e s a s u r g e . In a d i f f e r e n t a p p r o a c h , C l a r k e e t a l . (1984) p o s t u l a t e d i n t e r a c t i o n s between w a t e r s u p p l y , i c e o v e r b u r d e n , and a s y s t e m o f c h a n n e l s i n a p e r m e a b l e s e d i m e n t s u b s t r a t e . They p r o p o s e d t h a t t h e c h a n n e l s a r e i n a s t a t e o f f l u x , o p e n i n g and c l o s i n g u n t i l a s u r g e i s i n i t i a t e d by f a i l u r e o f t h e s u b s t r a t e due t o h i g h w a t e r p r e s s u r e i n a s y s t e m w i t h d e c r e a s e d c a p a c i t y . T h e s e h y p o t h e s e s i n d i c a t e t h e p o t e n t i a l i n f l u e n c e o f w a t e r , i c e and s u b s t r a t e i n t e r a c t i o n s i n s u r g i n g g l a c i e r s . 8 1.2.1 THE STUDY AREA The S t e e l e G l a c i e r a r e a of t h e S t . E l i a s Range, Yukon T e r r i t o r y , Canada ( F i g u r e 3) has a c o n c e n t r a t i o n of s u r g i n g g l a c i e r s . In a t r i b u t a r y v a l l e y o f S t e e l e , t h r e e s u b p o l a r s u r g i n g g l a c i e r s a r e i n d i f f e r e n t s u r g e s t a g e s : R u s t y G l a c i e r i s i n t h e q u i e s c e n t p h a s e , T r a p r i d g e G l a c i e r i s e n t e r i n g an a c t i v e p h a s e , and Backe G l a c i e r s u r g e d i n 1965-1967. 1 Over t h e p a s t 20 y e a r s , a l a r g e amount o f d a t a has been c o l l e c t e d on T r a p r i d g e G l a c i e r i n c l u d i n g v e l o c i t y , t e m p e r a t u r e and b a s a l w ater p r e s s u r e measurements ( C o l l i n s 1972; J a r v i s and C l a r k e 1975; C l a r k e e t a l . 1984). The f o l l o w i n g summary i s t a k e n f r o m p e r s o n a l o b s e r v a t i o n s , C l a r k e e t a l . ( 1 9 8 4 ) , and c o m m u n i c a t i o n s w i t h t h e a u t h o r s o f t h a t p a p e r . Over a p e r i o d o f 15 y e a r s , t h e l o w e r T r a p r i d g e G l a c i e r t h i c k e n e d a s a w a v e - l i k e b u l g e moved d o w n - g l a c i e r a t a p p r o x i m a t e l y 24 m a " 1 ( F i g u r e 4 ) . A b l a t i o n d o w n - g l a c i e r f r o m t h e b u l g e had removed most o f t h e l o w e r s t a g n a n t i c e by t h e summer of 1985. The b u l g e a f f e c t s b a s a l p r o c e s s e s by i n c r e a s i n g p r e s s u r e a t t h e bed and a d v e c t i n g c o l d i c e away from t h e bed t h e r e b y c h a n g i n g p r e s s u r e m e l t i n g c o n d i t i o n s . T e m p e r a t u r e measurements have shown t h a t t h e b u l g e marks t h e s e p a r a t i o n between f r o z e n and u n f r o z e n bed ( F i g u r e s 4 and 5 ) . C l a r k e e t a l . (1984) c a l c u l a t e d t h a t a h i g h h e a t f l u x c o u l d be s u s t a i n e d by r e l e a s e of g r a v i t a t i o n a l e n e r g y from s u b g l a c i a l w a t e r f l o w . T h i s h e a t f l u x may i n i t i a t e b a s a l m e l t i n g i n T r a p r i d g e G l a c i e r . 'Each g l a c i e r i s a p p r o x i m a t e l y 1 km wide and 5 km l o n g , c l a s s i f y i n g them as S u r g e Type I I I by M e i e r and P o s t ( 1 9 6 9 ) . 9 Figure 3. S u r g i n g G l a c i e r s o f t h e Mt S t e e l e A r e a , Yukon, Canada. The S t e e l e C r e e k b a s i n has a c o n c e n t r a t i o n o f s u r g i n g g l a c i e r s . The p r o b a b i l i t y o f a g l a c i e r b e i n g o f s u r g e - t y p e i s i d e n t i f i e d f o r g l a c i e r s i n t h e b a s i n ( f r o m C l a r k e 1976). 10 Hot w a t e r d r i l l i n g r e v e a l s a complex s u b g l a c i a l d r a i n a g e s y s t e m i n T r a p r i d g e G l a c i e r . C o n n e c t i o n t o t h e bed c a u s e s some h o l e s t o d r a i n c o m p l e t e l y and p r e s s u r e measurements i n o t h e r h o l e s show f l u c t u a t i o n s a p p r o a c h i n g f l o t a t i o n (90% o f i c e d e p t h ) . When dye was i n j e c t e d i n t o t h e s e c o n n e c t e d h o l e s , i t was not o b s e r v e d downstream, s u g g e s t i n g t h a t t h e d r a i n a g e s y s t e m c o n t i n u e s t h r o u g h m o r a i n a l m a t e r i a l r a t h e r t h a n i n t o t h e s u r f a c e s t r e a m s o r t h a t t h e w ater i s p o n d i n g i n t h e s u b s t r a t e . B e c a u s e of t h e low g r a d e m etamorphic r o c k s and f r a c t u r e d v o l c a n i c r o c k s , and t h e p r o p e r t i e s of e x p o s e d t i l l s , C l a r k e e t a l . (1984) p o s t u l a t e d a p e r m e a b l e and d e f o r m a b l e s u b s t r a t e i n w h i c h d r a i n a g e c h a n n e l s were c o n t i n u o u s l y e v o l v i n g , o p e n i n g and c l o s i n g d e p e n d i n g upon p o r e p r e s s u r e s , d e f o r m a t i o n s , p i p i n g , and o t h e r p r o c e s s e s . As t h e s u b s t r a t e d e f o r m s , d e s t r u c t i o n o f t h e s u b g l a c i a l d r a i n a g e s y s t e m c o u l d i n i t i a t e a s u r g e ( J o n e s 1979). In a p e r m e a b l e s u b s t r a t e w i t h v a r i a t i o n s i n w a t e r p r e s s u r e and s u p p l y , i s o t o p i c e f f e c t s of f r e e z i n g p r o c e s s e s may be d i f f e r e n t f r o m b u l k w a t e r f r a c t i o n a t i o n s . To examine t h e e f f e c t s of f r e e z i n g f r o m a s e d i m e n t s u b s t r a t e , i s o t o p i c p r o p e r t i e s of b a s a l i c e c a n be c o n t r a s t e d w i t h p r o p e r t i e s o f b u l k i c e . 1.3 ISOTOPES D i f f e r e n t s t a g e s of w a t e r e v o l u t i o n i n a g l a c i a l s y s t e m a r e i l l u s t r a t e d i n F i g u r e 6. I w i l l d e v e l o p a p a r a l l e l framework of f r a c t i o n a t i o n p r o c e s s e s t h a t a f f e c t t h e i s o t o p i c c o m p o s i t i o n d u r i n g e v o l u t i o n between s t a g e s . T h e s e f r a c t i o n a t i o n s a r e c a u s e d by t h e v a r i a t i o n s i n m o l e c u l a r w e i g h t , bond l e n g t h , and 11 F i g u r e 4 . Summary of T r a p r i d g e measurements from 1969-1981. The l a r g e c l o s e d c i r c l e s r e p r e s e n t d e p t h s d e t e r m i n e d by h o t w a t e r d r i l l i n g ; open c i r c l e s a r e s u r v e y e d s u r f a c e p r o f i l e s and t h e a r r o w s i n d i c a t e v e l o c i t i e s a t t h e s i t e s ; t h e t h i n d a s h e d l i n e s show t h e 1980 s u r f a c e p r o f i l e . The m a j o r f e a t u r e s a r e : emergent v e l o c i t i e s a t S t a k e s G and H i n 1969 and no m e a s u r a b l e f l o w a t F i n d i c a t i n g t h e d e v e l o p i n g b u l g e ; t h e r m a l p r o f i l e o f 1980 shows t h e s e p a r a t i o n between f r o z e n and u n f r o z e n bed; e n h a n c e d b a s a l s l i d i n g i n t h e u n f r o z e n zone has c a u s e d an a p p r o x i m a t e f i v e - f o l d i n c r e a s e i n s u r f a c e v e l o c i t i e s above t h e b u l g e between 1969 and 1980; t h e v e l o c i t y o f t h e b u l g e m i g r a t i o n was 24 ma" 1 between 1980 and 1981, t h e same a s t h e v e l o c i t y a t s i t e 6 ( f r o m C l a r k e e t a l . 1984). 12 13 F i g u r e 5. T e m p e r a t u r e p r o f i l e s f o r T r a p r i d g e G l a c i e r . The t h e r m a l g r a d i e n t s i n T r a p r i d g e were d e t e r m i n e d f r o m t h e r m i s t o r measurements between 1980 and 1984. The b a s a l h e a t f l u x i s l o w e r i n t h e upper g l a c i e r ( s i t e s 9 and 1 1 ) . The b a s a l h e a t f l u x a t s i t e 3 i s 540 mWm"2, many t i m e s g r e a t e r t h a n t h e e x p e c t e d g e o t h e r m a l h e a t f l u x ( f r o m C l a r k e e t a l . 1984). -7 T E M P E R A T U R E (°C) -6 -5 -4 -3 -2 -1 0 1 1 4 i n t e r m o l e c u l a r a t t r a c t i o n t h a t a r e a s s o c i a t e d w i t h i s o t o p i c s u b s t i t u t i o n i n wa t e r m o l e c u l e s . The common w a t e r s p e c i e s o f i n t e r e s t , and t h e i r a p p r o x i m a t e m o l e c u l a r w e i g h t s , a r e : H 2 0 1 6 -18 ; HDO 1 6 - 19 ; H 2 0 1 8 - 2 0 . 1 I w i l l o u t l i n e t h e i s o t o p i c methods t h a t a r e u s e d t o s t u d y t h e s e m o l e c u l e s and f r a c t i o n a t i o n p r o c e s s e s ; f o r f u r t h e r d e t a i l s o f i s o t o p i c r e s e a r c h , I recommend two r e v i e w b o o k s , F r i t z and F o n t e s ( 1 9 8 0 ) , and Gat and G o n f i a n t i n i ( 1 9 8 1 ) . I s o t o p i c c o m p o s i t i o n s a r e r e p r e s e n t e d by R, t h e r a t i o o f t h e c o n c e n t r a t i o n o f t h e l e a s t a b u n d a n t m o l e c u l e o v e r t h e c o n c e n t r a t i o n o f t h e common m o l e c u l e , e . g . ( 0 1 8 ) v [1 ] R v ( 0 1 8 ) = ( 0 1 6 ) v f o r oxygen i n t h e v a p o u r phase ( v ) . R a t i o s a r e u s e d b e c a u s e o f th e d i f f i c u l t i e s o f m e a s u r i n g a b s o l u t e c o m p o s i t i o n s . The 6 v a r i a b l e i s u s e d t o r e f e r e n c e a l l r a t i o s t o a s t a n d a r d R x [2] 8 X = - 1 Rvsmow where x r e f e r s t o t h e sample, VSMOW t o t h e r e f e r e n c e , and R t o th e r e s p e c t i v e r a t i o o f heavy t o l i g h t i s o t o p e . 2 I s o t o p i c c o m p o s i t i o n s o f d e u t e r i u m and O 1 8 , 5D and 5 0 1 8 r e s p e c t i v e l y , a r e 1D i s d e u t e r i u m . O t h e r water m o l e c u l e s e x i s t b u t t h e s e t h r e e a r e th e most common, and t h e ones t h a t a r e g e n e r a l l y u s e d i n s t a b l e i s o t o p i c s t u d i e s on g l a c i e r s . T h e i r a v e r a g e r a t i o i n t h e water c y c l e i s , l i g h t e s t t o h e a v i e s t , 997,680:320:2000 ( D a n s g a a r d 1 964) . 2VSMOW r e f e r s t o V i e n n a S t a n d a r d Mean Ocean Water, an a r t i f i c i a l l y p r e p a r e d water w i t h 8 v a l u e s t h a t c l o s e l y match t h e a v e r a g e of a n a l y s e s o f oce a n w a t e r by C r a i g ( 1 9 6 1 ) . 15 F i g u r e 6. Water e v o l u t i o n i n a g l a c i a l s y s t e m . A s i m p l i f i e d framework o f t h e s t a g e s of e v o l u t i o n of water i n a g l a c i a l s y s t e m . S u r f a c e m e l t w a t e r can r e a c h t h e b a s a l s y s t e m t h r o u g h e n g l a c i a l c h a n n e l s . The water may be s t o r e d i n f i r n and r e l e a s e d o v e r t i m e . GLOBAL RESERVOIR o c e a n w a t e r f r e s h w ater ATMOSPHERIC WATER SNOW LAYERS Snow i n t e r s t i t i a l w a t e r MELTWATER ENGLACIAL WATER FIRN s t o r e d w a t e r f i r n SUBSTRATE WATER b a s a l w a t e r s u r f a c e water BASAL DISCHARGE BASAL ICE BULK ICE 16 u s u a l l y r e p o r t e d i n °/oo ( p a r t s p e r t h o u s a n d ) . 1 D i f f e r e n c e s i n i n t e r m o l e c u l a r f o r c e s and m o l e c u l a r w e i g h t s of t h e i s o t o p i c w a ter s p e c i e s i n f l u e n c e p h y s i c a l p r o p e r t i e s of t h e m o l e c u l e s ( T a b l e 1 ) , c a u s i n g f r a c t i o n a t i o n o f i s o t o p e s d u r i n g p h a s e c h a n g e s ; a t a g i v e n t e m p e r a t u r e under e q u i l i b r i u m c o n d i t i o n s , t h e i s o t o p i c c o m p o s i t i o n i n e a c h p h a s e i s d i f f e r e n t : e . g . b e c a u s e o f t h e d e p l e t i o n of heavy i s o t o p e s d u r i n g e v a p o r a t i o n f r o m ocean w a t e r , t h e m a j o r i t y o f s amples f r o m t h e w a t e r c y c l e have n e g a t i v e 6 v a l u e s . The r a t i o of i s o t o p i c c o n c e n t r a t i o n s between two p h a s e s i s r e p r e s e n t e d by a f r a c t i o n a t i o n f a c t o r [3] a = — R 2 where R, and R 2 a r e t h e r a t i o s o f heavy t o l i g h t i s o t o p e i n d i f f e r e n t p h a s e s . 2 In a f r a c t i o n a t i o n p r o c e s s w h i c h has a c o n s t a n t a, t h e i s o t o p i c r a t i o o f a p r o d u c t c a n be c a l c u l a t e d f r o m where f i s t h e r e m a i n i n g f r a c t i o n of o r i g i n a l r e a c t a n t , and R 0 i s 1 C o n f u s i o n c a n a r i s e from an a l t e r n a t i v e r e p r e s e n t a t i o n where °/oo i s t r e a t e d as a u n i t and t h e r i g h t hand s i d e of t h e d e f i n i n g e q u a t i o n i s m u l t i p l i e d by 1000. I have w r i t t e n t h i s e q u a t i o n t r e a t i n g °/oo a s p e r c e n t a g e s a r e t r e a t e d , as a m a t h e m a t i c a l f a c t o r n o t a u n i t . 2 I n t h i s t h e s i s a r e p r e s e n t s t h e o b s e r v e d f r a c t i o n a t i o n and a T i s an e q u i l i b r i u m f r a c t i o n a t i o n f a c t o r , a i s u s e d i n t h e f o r m where a>1, t h e r e f o r e R,>R 2. a~, u s e d by some r e s e a r c h e r s , r e p r e s e n t s t h e r e c i p r o c a l o f a. 17 T a b l e 1. P r o p e r t i e s of i s o t o p i c w ater s p e c i e s . The i n f l u e n c e o f b o n d i n g c h a r a c t e r i s t i c s p r o p e r t i e s between t h e from Gat 1981). G e n e r a l P r o p e r t i e s M e l t i n g P o i n t (°C) V i s c o s i t y (cP a t 20 °C) D i f f u s i o n C o e f f i c i e n t ( 1 0 s c m 2 s e c " 1 ) ( t h r o u g h o r d i n a r y w a t e r ) of D a r e e v i d e n t i n t h e d i f f e r e n c e s i n h e a v i e r i s o t o p e s ( D a t a n o t r e f e r e n c e d , H 2 0 1 6 0.00 1 .002< HDO 1.1248 2.34 D 2 0 3.81 1 .2471 H 2 0 1 8 0 . 2 8 1 . 0 5 6 4 2 . 6 6 Vapour P r e s s u r e R a t i o s 0.0°C 20.0°C 100.0°C H 20/HDO 1.12" 1 .07" 1.026" H 2 0 / H 2 0 1 8 1.0094 1.0050 H 2 0 / D 2 0 1 . 2 5 " 1 . 1 5 2 9 ( 1 . 1 5 ) i 1 . 0 3 2 6 ( 1 . 0 5 2 ) i E q u i l i b r i u m I s o t o p i c F r a c t i o n a t i o n F a c t o r s S o l i d / V a p o u r 0 °C - 1 0 ° C L i q u i d / V a p o u r 20°C 0°C S o l i d / L i q u i d 0°C 1 32 151 ,084 ,111 1 . 0 2 0 8 f 1 . 0 ! 8 6 n a 0 i s 1.0152 1.0166 1.0098 1.0117 1.0035± 1 .003n f M a j o u b e (1971) ±Arnason (1969a) n O ' N e i l l (1968) • K i r s h e n b a u m (1951) »Weast (1984) 18 t h e i n i t i a l i s o t o p i c r a t i o . In t h e s p e c i a l c a s e where a i s .equal t o a T , t h 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 f a c t o r , t h i s e q u a t i o n i s t e r m e d a R a y l e i g h e q u a t i o n . Most p r o c e s s e s a r e i n i t i a l l y m o d e l l e d as a R a y l e i g h t y p e , an e q u i l i b r i u m p r o c e s s where t h e p r o d u c t i s removed i m m e d i a t e l y upon f o r m a t i o n . B e c a u s e o f n o n - e q u i l i b r i u m o r k i n e t i c i s o t o p e e f f e c t s , o b s e r v e d f r a c t i o n a t i o n f a c t o r s d i f f e r f r o m t h e o r e t i c a l e q u i l i b r i u m f a c t o r s . D u r i n g p h a s e c h a n g e s , v a r i a t i o n s i n m o l e c u l a r p r o p e r t i e s c a u s e d i f f e r e n t f r a c t i o n a t i o n s f o r t h e two heavy i s o t o p i c s p e c i e s . A p l o t o f 5D v e r s u s 8 0 1 8 p r o d u c e s c h a r a c t e r i s t i c c u r v e s ( s u b s e q u e n t l y r e f e r r e d t o as t h e heavy i s o t o p e r e l a t i o n s h i p o r s l o p e ) t h a t a r e u s e f u l f o r i d e n t i f y i n g d i f f e r e n t f r a c t i o n a t i o n p r o c e s s e s . In T a b l e 1, t h e i m p o r t a n c e o f i n t e r m o l e c u l a r e f f e c t s on d e u t e r i u m a r e a p p a r e n t i n t h e v i s c o s i t y and d i f f u s i o n p r o p e r t i e s . The d i f f e r e n t f r e e z i n g t e m p e r a t u r e s f o r t h e two heavy i s o t o p i c w a t e r m o l e c u l e s a l s o a f f e c t s t h e heavy i s o t o p e r e l a t i o n s h i p d u r i n g f r e e z i n g . F o r many p r o c e s s e s , t h i s heavy i s o t o p e r e l a t i o n s h i p c a n be a p p r o x i m a t e d by a s t r a i g h t l i n e t h a t i s u s e d t o r e p o r t t h e c h a r a c t e r i s t i c s of a p r o c e s s , o r a sample s e t . I s o t o p i c c h a n g e s d u r i n g a p r o c e s s c a n a l s o be u s e d a s a measure of t h e mechanisms t h a t a f f e c t t h e p r o c e s s . I s o t o p i c c o m p o s i t i o n o f a p r o d u c t c a n change d u r i n g t h e p r o c e s s due t o e x t e r n a l i n f l u e n c e s s u c h as t e m p e r a t u r e and i n p u t w a t e r . I use h e a v y i s o t o p e r e l a t i o n s h i p s and i s o t o p i c s t r a t i g r a p h y t o c h a r a c t e r i z e t h e f o l l o w i n g f r a c t i o n a t i o n p r o c e s s e s t h a t a r e s i g n i f i c a n t i n t h e g l a c i a l e n v i r o n m e n t : 1. M e t e o r i c P r o c e s s e s 19 2. Snow/Ice E v o l u t i o n 3. G e o c h e m i c a l F r a c t i o n a t i o n s . 1.3.1 METEORIC PROCESSES A t m o s p h e r i c f r a c t i o n a t i o n e f f e c t s a r e d o m i n a t e d by t h e c o n d e n s a t i o n , e v a p o r a t i o n and s u b l i m a t i o n mechanisms a s s o c i a t e d w i t h p r e c i p i t a t i o n . A l t h o u g h t h e a l t i t u d e , l a t i t u d e , and h i s t o r y of a s t o r m p a t h a l t e r 5 v a l u e s , t e m p e r a t u r e i s t h e major i n f l u e n c e on i s o t o p i c c o m p o s i t i o n . B e c a u s e warmer t e m p e r a t u r e s c a u s e summer p r e c i p i t a t i o n t o have h i g h e r c o n c e n t r a t i o n s o f heavy i s o t o p e s t h a n w i n t e r p r e c i p i t a t i o n , s e a s o n a l and l o n g - t e r m c l i m a t i c v a r i a t i o n s c a n be i n f e r r e d f r o m t h e i s o t o p i c v a r i a t i o n s t h a t a r e o f t e n p r e s e r v e d i n g l a c i e r i c e . The h e a v y i s o t o p e r e l a t i o n s h i p d e t e r m i n e d f rom p r e c i p i t a t i o n c o l l e c t e d by t h e w o r l d network of t h e I n t e r n a t i o n a l A t o m i c E n e r g y Agency ( Y u r t s e v e r and Gat 1981) i s 8D = 8 . 2 05O 1 8 + 1 0 . 8 0 ° / o o • 1 T h i s r e s u l t i s s i m i l a r t o t h e commonly r e f e r e n c e d C r a i g (1961) r e s u l t o f s l o p e 8, and i n t e r c e p t 1 0 ° / O O « A s l o p e v a l u e o f 8 i s a p p r o x i m a t e l y t h a t of an e q u i l i b r i u m e v a p o r a t i o n o f VSMOW i n a d i s t i l l a t i o n column w i t h an e q u i l i b r i u m p r o c e s s o f p r e c i p i t a t i o n , e i t h e r c o n d e n s a t i o n o r s u b l i m a t i o n . E q u i l i b r i u m c o n d e n s a t i o n models of p r e c i p i t a t i o n p r e d i c t s l o p e s r a n g i n g f r o m 9.59 a t 0 °C, 'The s l o p e and i n t e r c e p t were c a l c u l a t e d by r e d u c e d major a x i s ( Y u r t s e v e r and Gat 1981). S e c t i o n 2.4 i n c l u d e s a d i s c u s s i o n on t h e t e c h n i q u e s o f s l o p e a n a l y s i s when t h e u n c e r t a i n t y i n b o t h v a r i a b l e s i s s i m i l a r . 20 t o 8.22 a t 30 °C (Gat 1981), and 8.13 a t 0 °C t o 7.96 a t 30 °C ( C r a i g and Gordon 1965). B e c a u s e of k i n e t i c e x c h a n g e s a t t h e o c e a n s u r f a c e and i n t h e a t m o s p h e r e , p r e c i p i t a t i o n r e s u l t s d i f f e r f r o m t h e e q u i l i b r i u m m o d e l s . M e r l i v a t and C o a n t i c (1975) p r e d i c t e d s l o p e s r a n g i n g f r o m 3 t o 7 f o r a n o n - e q u i l i b r i u m model o f e v a p o r a t i o n t h a t i n t r o d u c e d a k i n e t i c e f f e c t i n a d i f f u s i o n l a y e r above a water s u r f a c e . S l o p e s i n t h i s r a n g e a r e o f t e n m e asured f o r b o d i e s of w a t e r t h a t u n d e r g o s i g n i f i c a n t e v a p o r a t i o n i n t o a warm a t m o s p h e r e , however, most m e t e o r i c s a m p l e s and many g l a c i e r s a m p l e s have 8 v a l u e s t h a t a p p r o x i m a t e a l i n e o f s l o p e 8 on 6 D / 8 0 1 8 g r a p h s . 1.3.2 SNOW/ICE EVOLUTION S u b l i m a t i o n , e v a p o r a t i o n , c o n d e n s a t i o n , and c i r c u l a t i o n of r a i n o r m e l t w a t e r f r a c t i o n a t e i s o t o p e s d u r i n g e v o l u t i o n o f p r e c i p i t a t i o n t o g l a c i e r i c e . In t h i s s e c t i o n I c o n s i d e r t h e i n f l u e n c e o f t h e s e p r o c e s s e s on t h e i s o t o p i c p r o p e r t i e s of b a s a l and b u l k i c e . 1.3.2.1 E v a p o r a t i o n / S u b l i m a t i o n F r a c t i o n a t i o n s E q u i l i b r i u m e v a p o r a t i o n / s u b l i m a t i o n e n r i c h e s heavy i s o t o p e s i n l i q u i d / s o l i d s t a t e s p r o d u c i n g heavy i s o t o p e s l o p e s r a n g i n g from 8.68 a t 0 °C t o 9.10 a t -10 °C (Majoube 1971). S l o p e s of t h i s m a g n i t u d e have n o t been o b s e r v e d on g l a c i e r s . Moser and S t i c h l e r (1970, 1975) d e t e r m i n e d two o p p o s i n g e f f e c t s i n a s t u d y of snow a g i n g on g l a c i e r s u r f a c e s i n t h e A l p s . D u r i n g t h e day, heavy i s o t o p e s were c o n c e n t r a t e d i n t h e snow b e c a u s e of p r e f e r e n t i a l r e m o v a l o f l i g h t i s o t o p e i n t o t h e a t m o s p h e r e by 21 e v a p o r a t i o n and s u b l i m a t i o n . A t n i g h t , l o w e r 6 v a l u e s i n c o l d n i g h t a i r i n c r e a s e d c o m p o s i t i o n s o f l i g h t i s o t o p e s t h r o u g h c o n d e n s a t i o n and s u b l i m a t i o n ( v a p o u r t o s o l i d ) on t h e snow. I n t h e 1970 p a p e r , t h e y r e p o r t e d 5 D / 8 0 1 8 s l o p e s o f 8 f o r f r e s h snow, and 7 f o r pack snow i n t h e A l p s , w i t h r a p i d v a r i a t i o n o f 5 v a l u e s o v e r t i m e i n snowpacks n e a r f r e e z i n g t e m p e r a t u r e s , b u t no l a r g e v a r i a t i o n s between -5 °C and -15 °C o v e r s h o r t t i m e p e r i o d s . From l a b o r a t o r y measurements o f a s l o p e o f 5.75 f o r an i s o t o p i c a l l y homogeneous snow s u b l i m a t i n g a t -10 °C, t h e y c o n c l u d e d t h a t s u b l i m a t i o n f r o m snow t o v a p o u r d o m i n a t e s e v e r t h e n i g h t l y c o n d e n s a t i o n / s u b l i m a t i o n p r o c e s s e s . 1 M a r t i n e c e t a l . (1975) o b s e r v e d k i n e t i c e v a p o r a t i o n n e a r t h e s u r f a c e o f a snowpack, and v a p o u r exchange between snow l a y e r s h a v i n g s i g n i f i c a n t l y d i f f e r e n t i s o t o p i c c o m p o s i t i o n s . From o b s e r v a t i o n s o f exchange between snow i n l a y e r s away from a t m o s p h e r i c c o n t a c t and p e r c o l a t i n g m e l t w ater and p r e c i p i t a t i o n , t h e y s u g g e s t e d t h a t m e l t i n g / f r e e z i n g p r o c e s s e s a l s o a f f e c t t h e i s o t o p i c e v o l u t i o n of b u l k and b a s a l i c e . 1.3.2.2 M e l t / F r e e z e F r a c t i o n a t i o n s A r n a s o n (1981) s t a t e s t h a t i c e / w a t e r f r a c t i o n a t i o n s d o m i n a t e i n wet snow z o n e s , whereas i c e / v a p o u r p r o c e s s e s a r e more s i g n i f i c a n t i n d r y snow z o n e s . S i n c e f r e e z i n g t e m p e r a t u r e s o f d e u t e r i u m w a t e r and O 1 8 water a r e h i g h e r t h a n f o r common water ( T a b l e 1 ) , c o n c e n t r a t i o n s of heavy i s o t o p e s s h o u l d be h i g h e r i n i c e t h a n i n t h e water from w h i c h i t was f o r m e d . From e a r l y 1 M o s e r and S t i c h l e r d e s c r i b e d t h e l a b o r a t o r y p r o c e s s e s as e v a p o r a t i o n and c o n d e n s a t i o n , but a t -10 °C s u b l i m a t i o n may have been t h e dom i n a n t p r o c e s s . 22 e x p e r i m e n t a l d a t a , Weston (1955) c a l c u l a t e d t h e m a g n i t u d e of t h e e f f e c t f o r f r e e z i n g o f d e u t e r i u m water and s p e c u l a t e d t h a t a c o n d i t i o n r e q u i r e d f o r l a b o r a t o r y measurements would be slow f r e e z i n g . P o s e y and S m i t h (1957) o b s e r v e d i s o t o p i c f r a c t i o n a t i o n f o r d e u t e r i u m water by u s i n g slow f r e e z i n g and a g i t a t i o n f o r good m i x i n g . O ' N e i l l (1968) a c c u r a t e l y measured t h e f r a c t i o n a t i o n f a c t o r s o f oxygen and h y d r o g e n i n an i c e / w a t e r s y s t e m u s i n g a mass s p e c t r o m e t e r . H i s v a l u e s f o r t h e f r a c t i o n a t i o n f a c t o r s C I Q = 1.0-186, a o i 8 = 1 .003, a r e s t i l l u s e d by r e s e a r c h e r s . S u b s e q u e n t l y , A r n a s o n (1969a) d e t e r m i n e d a v a l u e o f arj=1.0208 and Majoube (1971) measured a v a l u e o f a Q i 8 = l . 0 0 3 5 . A r n a s o n ( 1 9 7 0 ) , ( 1 9 8 1 ) , A r n a s o n e t a l . ( 1 9 7 3 ) , and Buason (1972) d e v e l o p e d a t h e o r y of i n t e r a c t i o n s between i c e and w a t e r i n m e l t i n g snowpacks. In I c e l a n d , where summer p r e c i p i t a t i o n has 6 v a l u e s s i m i l a r t o w i n t e r p r e c i p i t a t i o n , A r n a s o n (1969b) measured an i n c r e a s e of d e u t e r i u m c o n c e n t r a t i o n i n snow as m e l t w a t e r and r a i n w a t e r p e r c o l a t e d t h r o u g h t h e snow. Buason (1972) d e v e l o p e d a model d e s c r i b i n g a p a r t i a l e q u i l i b r i u m s t a t e between w a t e r and snow w h i c h a g r e e d w i t h t h e f i e l d r e s u l t s when a t u n i n g f a c t o r r e l a t i n g t o t h e d e g r e e of e x c h a n g e was a p p l i e d ( A r n a s o n e t a l . 1973). S i n c e t h e I c e l a n d i c c o n d i t i o n s p r e c l u d e d t h e p o s s i b i l i t y o f i s o t o p i c e n r i c h m e n t of t h e snow from h e a v i e r summer p r e c i p i t a t i o n , A r n a s o n (1981) c o n c l u d e d t h a t t h e r e s u l t s d e m o n s t r a t e d i c e / w a t e r f r a c t i o n a t i o n s . U n f o r t u n a t e l y , t h i s work d i d n o t i n c l u d e t h e measurement o f S O 1 8 . M a r t i n e c e t a l . (1975) o b s e r v e d a s i m i l a r e n r i c h m e n t i n snowpacks w i t h p e r c o l a t i n g m e l t w a t e r . From p a r a l l e l measurements o f 5 0 1 8 t h e y d e t e r m i n e d a 23 s l o p e o f 7.2 f o r t h e heavy i s o t o p e r e l a t i o n s h i p . B e c a u s e o f t h e s h o r t r e s i d e n c e t i m e of water i n t h e snow, t h e y p o s t u l a t e d t h a t e n r i c h m e n t i n r u n o f f w ater r e s u l t e d from e v a p o r a t i o n r a t h e r t h a n a p e r c o l a t i o n p r o c e s s . S o u c h e z and J o u z e l ( 1 9 8 4 ) , J o u z e l and S o u c h e z ( 1 9 8 2 ) , and S o u c h e z and De G r o o t e (1985) m o d e l l e d i c e / w a t e r f r a c t i o n a t i o n p r o c e s s e s a s c l o s e d and open s y s t e m s u n d e r g o i n g a R a y l e i g h - t y p e p r o c e s s i n w h i c h t h e p r o d u c t , i c e , d o e s n o t c h a n g e i t s i s o t o p i c c o m p o s i t i o n b e c a u s e i t i s e f f e c t i v e l y removed f r o m t h e s y s t e m . From f r e e z i n g e x p e r i m e n t s o f A r c t i c , A n t a r c t i c and A l p i n e w a t e r s i n a s i m u l a t e d open s y s t e m , t h e y f o u n d t h a t t h e i n i t i a l i c e f o r m e d was e n r i c h e d o v e r t h e i n i t i a l water 5 v a l u e s . As f r e e z i n g p r o g r e s s e d n e w l y - f o r m e d i c e was l i g h t e r t h a n t h e i n i t i a l i c e , but s t i l l e n r i c h e d compared t o t h e r e m a i n i n g w a t e r . The heavy i s o t o p e r e l a t i o n s h i p s were a p p r o x i m a t e l y s t r a i g h t l i n e s w i t h s l o p e s d e p e n d e n t upon t h e i n i t i a l h e a v y i s o t o p e r a t i o and t h e f r a c t i o n a t i o n c o e f f i c i e n t . In t h e 1982 p a p e r t h e y t h e o r i z e d a c l o s e d s y s t e m s l o p e o f ( a D - 1 ) (1+ 6D. ) [5] S = x — ( a 0 i 8 - 1 ) ( 1 + 5 0 1 8 . ) where i r e f e r s t o t h e i n i t i a l w a t e r . S u b s e q u e n t l y , t h e y p o s t u l a t e d an open s y s t e m s l o p e w h i c h i s n o t a f f e c t e d by r a t e s o f i n p u t , o u t p u t , and f r e e z i n g , a l t h o u g h t h e r a n g e o f t h e 5 v a l u e s c o u l d be c h a n g e d ( S o u c h e z and J o u z e l 1984). W i t h t h e a s s u m p t i o n t h a t i n p u t 6 v a l u e s from a r e s e r v o i r a r e c o n s t a n t , t h e y c a l c u l a t e d an open s y s t e m s l o p e o f 24 p , a D ( a D - 1 ) ( 1 + 5D.) [6] S = _ _ 1 . a 0 i 8 ( a 0 i 8 - 1 ) ( 1 + 5 0 1 B i ) U s i n g t h e R a y l e i g h e q u a t i o n t h e y c a l c u l a t e d e ( t h e e f f e c t i v e e n r i c h m e n t f a c t o r ) f o r d e u t e r i u m and 0 1 8 and g r a p h i c a l l y d e t e r m i n e d t h a t e q u i l i b r i u m and n o n - e q u i l i b r i u m f r e e z i n g p r o c e s s e s would p l o t on t h e same l i n e on a 5 D / 6 0 1 8 g r a p h . In a d d i t i o n , Souchez and De G r o o t e (1985) examined s l o p e change f o r an i s o t o p i c a l l y v a r i a b l e r e s e r v o i r u s i n g a v a r i a t i o n o f E q u a t i o n 6 w h i c h i n c l u d e d t e r m s f o r i n p u t , o u t p u t and f r e e z i n g r a t e c h a n g e s . T h e s e s t u d i e s examined i s o t o p i c e f f e c t s d u r i n g f r e e z i n g o f b u l k w a t e r . C i r c u l a t i o n and f r e e z i n g o f b a s a l w ater i n a s o i l m edia may ' i m p r i n t i s o t o p i c e f f e c t s o v e r t h e i n f l u e n c e s of b u l k w a t e r f r e e z i n g p r o c e s s e s . T h e s e g e o c h e m i c a l e f f e c t s must a l s o be c o n s i d e r e d . 1.3.3 GEOCHEMICAL FRACTIONATION D u r i n g w e a t h e r i n g p r o c e s s e s i n a low t e m p e r a t u r e e n v i r o n m e n t (25 ° C ) , i s o t o p i c exchange between water and m i n e r a l s i n r o c k o r s e d i m e n t i s n e g l i g i b l e i n t h e s h o r t t e r m ( l e s s t h a n one m i l l i o n y e a r s , S a v i n and E p s t e i n 1970; Lawrence and T a y l o r 1972). Water f l o w t h r o u g h c o m p a c t e d c l a y s and s h a l e s c a n f r a c t i o n a t e t h e i s o t o p i c s p e c i e s t h r o u g h ultrafiltration. U l t r a f i l t r a t i o n i s a p r o c e s s t h a t r e t a r d s f l o w o f i o n s and i s o t o p e s t h r o u g h a media ( s o i l o r r o c k ) . B e c a u s e o f g r e a t e r mass and d i f f e r e n t b o n d i n g c h a r a c t e r i s t i c s , heavy i s o t o p e water m o l e c u l e s can be p r e f e r e n t i a l l y s l o w e d d u r i n g p a s s a g e t h r o u g h p o r e s by t h e s u r f a c e 25 f o r c e s i n d o u b l e l a y e r s . 1 In d e e p - s e d i m e n t i n t e r s t i t i a l w a t e r , G r a f e t a l . (1965) o b s e r v e d an i n c r e a s e i n 5 0 1 8 and SD w i t h d e p t h . They d e t e r m i n e d a s l o p e of 3.1 f o r t h e heavy i s o t o p e r e l a t i o n s h i p and h y p o t h e s i z e d t h a t f r a c t i o n a t i o n e f f e c t s m i g h t o c c u r b e c a u s e of f i l t r a t i o n t h r o u g h s h a l e s . The l o w e r l i m i t of t h e s l o p e was p o s t u l a t e d t o be 0.5, w h i c h r e p r e s e n t s a p u r e d i f f u s i o n mechanism. The i s o t o p i c p r e f e r e n c e was a t t r i b u t e d t o v i s c o s i t y d i f f e r e n c e s and l a r g e r e f f e c t s were s e e n f o r m o l e c u l a r c o n f i g u r a t i o n c h a n g e s ( g r e a t e r i n f l u e n c e on D ) , t h a n f o r mass c h a n g e s . C o p l e n and Hanshaw (1973) o b s e r v e d an e n r i c h m e n t of heavy i s o t o p e s i n remnant water a f t e r f o r c e d f l o w t h r o u g h c o m p a c t e d c l a y d i s c s . The u l t r a f i l t r a t e ( e f f l u e n t ) was d e p l e t e d by 2 . 5 ° / 0 0 i n d e u t e r i u m , and 0 . 8 ° / O o i n O 1 8 . They m o d e l l e d t h e p r o c e s s as a R a y l e i g h - t y p e and c a l c u l a t e d ' f l o w f r a c t i o n a t i o n f a c t o r s ' of a D"=0.99772, and a 0 1s"=0.99928 f o r d i s t i l l e d w a t e r , and 0.99825 and 0.99930 f o r 0.01N N a C l s o l u t i o n s . C o p l e n and Hanshaw c o n c l u d e d t h a t t e m p e r a t u r e , c o m p o s i t i o n of t h e a d s o r b e n t , and t y p e o f b o n d i n g s t a t e c a u s e t h e i r o b s e r v e d a v e r a g e s l o p e o f 3.1 f o r t h e heavy i s o t o p e r e l a t i o n s h i p , t h e same s l o p e v a l u e as G r a f e t a l . ( 1 9 6 5 ) . They p r e d i c t e d u l t r a f i l t r a t i o n w o u l d a l t e r m e t e o r i c s a m p l e s s u c h t h a t t h e u l t r a f i l t r a t e would be s h i f t e d t o t h e l e f t o f t h e m e t e o r i c l i n e , and t h e remnant f l u i d w ould be s h i f t e d t o t h e r i g h t o f t h e 1 i n e . In a g l a c i a l s u b s t r a t e , u l t r a f i l t r a t i o n i s de p e n d e n t upon t h e amount o f w a t e r t h a t i s a f f e c t e d by s u r f a c e f o r c e s . S p e c i f i c 1 K h a r a k a and B e r r y (1973) d i s c u s s e s i o n u l t r a f i l t r a t i o n p r o c e s s e s w h i c h a r e a p p l i c a b l e t o i s o t o p i c f r a c t i o n a t i o n s . 26 s u r f a c e a r e a and p o r e s i z e s w i l l d e t e r m i n e t h e f r a c t i o n o f w a t e r t h a t i s a d s o r b e d . The u l t r a f i l t r a t i o n f r a c t i o n a t i o n e f f e c t i s p r o b a b l y s m a l l i n s o i l s t h a t have o n l y s m a l l f r a c t i o n s of c l a y . 1 In f r e e z i n g s o i l s w i t h i n t e r s t i t i a l i c e , however, w a t e r c h a n n e l s become narrow and w a t e r t h a t f l o w s t o a f r e e z i n g p l a n e t h r o u g h an a d s o r b e d f i l m w i l l be i n f l u e n c e d by s u r f a c e f o r c e s . The i c e and s o i l s u r f a c e s may p r e f e r e n t i a l l y a d s o r b t h e h e a v y i s o t o p e s d u r i n g f l o w , t h e r e b y d e c r e a s i n g t h e i s o t o p i c c o m p o s i t i o n of n e w l y - f o r m i n g i c e . I f t h e r e i s f r e e z i n g by i c e s e g r e g a t i o n a t a g l a c i e r b ed, t h i s f r e e z i n g u l t r a f i l t r a t i o n mechanism may i n f l u e n c e t h e i s o t o p i c c o m p o s i t i o n o f b a s a l i c e . 1.3.4 BULK ICE EVOLUTION In t h e S t . E l i a s M o u n t a i n s , West and K r o u s e (1972) m e a s u r e d a m e t e o r i c h e a v y i s o t o p e r e l a t i o n s h i p of 6D = 8.2 5 0 1 B + 6 . 5 ° / 0 0 (two samples were from R u s t y G l a c i e r w h i c h i s a d j a c e n t t o Backe and T r a p r i d g e G l a c i e r s ) . Y u r t s e v e r and Gat (1981) d e t e r m i n e d a r e l a t i o n s h i p o f 8D = 7.95 5 0 1 8 + 6 . 3 ° / 0 0 f o r s a m p l e s f r o m t h e N o r t h e r n S t a t i o n s of t h e IAEA (one s t a t i o n was W h i t e h o r s e w h i c h i s a p p r o x i m a t e l y 200 km SE of t h e s t u d y a r e a ) . Snow e v o l u t i o n p r o c e s s e s u s u a l l y c a u s e g l a c i a l s a m p l e s t o 1 I n t h e e x p e r i m e n t s of C o p l e n and Hanshaw ( 1 9 7 3 ) , c l a y membranes had s m a l l p o r e s i z e s and t h e w a t e r was f o r c e d t h r o u g h a t h i g h p r e s s u r e s (>10" k P a ) . H y d r a u l i c c o n d u c t i v i t i e s were o f t h e o r d e r o f 1 0 " 1 5 m s " 1 compared t o 10~ 7 —10" 1 0 m s " 1 i n t i l l f r o m my s t u d y a r e a , a l t h o u g h e r r o r s f r o m inhomogeneous p r o p e r t i e s ( l a y e r e d f l o w ) c o u l d d e c r e a s e c o n d u c t i v i t i e s i n t h e upper s o i l l a y e r by many o r d e r s (Schmok, p e r s o n a l c o m m u n i c a t i o n ) . 27 be s h i f t e d t o t h e r i g h t o f t h e m e t e o r i c l i n e ( c o n c e n t r a t i o n o f heav y i s o t o p e s ) . The f i n a l i s o t o p i c c o m p o s i t i o n s of a p a r t i c u l a r sample w i l l d epend upon t h e i n i t i a l 6 v a l u e s , t h e f r a c t i o n a t i o n p r o c e s s e s , and t h e d e g r e e o f f r a c t i o n a t i o n . S i n c e i n d i v i d u a l s a m p l e s may be s h i f t e d by d i f f e r e n t amounts, i t i s n o t a l w a y s v a l i d t o c h a r a c t e r i z e snow e v o l u t i o n p r o c e s s e s by t h e s l o p e of a s t r a i g h t - l i n e r e l a t i o n s h i p on a 6 D / 5 0 1 8 g r a p h . A n o r m a l i s o t o p i c p r o f i l e o f a g l a c i e r h as s u r f a c e 6 v a l u e s t h a t i n c r e a s e f r o m t h e t e r m i n u s t o t h e e q u i l i b r i u m l i n e (a r e s u l t of f l o w f r o m t h e a c c u m u l a t i o n z one) and t h e n d e c r e a s e upwards t h r o u g h t h e a c c u m u l a t i o n zone (an a l t i t u d e e f f e c t on p r e c i p i t a t i o n ) . On R u s t y G l a c i e r , West and K r o u s e (1972) f a i l e d t o o b s e r v e a c o n s i s t e n t i s o t o p i c v a r i a t i o n w i t h a l t i t u d e , but t h e y d i d o b s e r v e abundant z o n e s o f s u p e r i m p o s e d i c e . A n a l y s e s o f snow p i t s and i c e c o r e s i n d i c a t e d t h a t i n t h e s o a k e d z o n e , i c e for m e d from snow i n one y e a r , and i n t h e p e r c o l a t i o n zone i c e for m e d i n two t o t h r e e y e a r s . B e c a u se snow and i c e e v o l u t i o n p r o c e s s e s c a u s e i s o t o p i c h o m o g e n i z a t i o n i n t h e l a y e r s , and s h i f t s i n t h e heavy i s o t o p e r e l a t i o n s h i p , t h e i s o t o p i c p a t t e r n i n some g l a c i e r s d i f f e r s from t h e n o r m a l one d e s c r i b e d a b o v e . In a d d i t i o n s u r g i n g g l a c i e r s c an have d i s c o n t i n u i t i e s due t o t h e p e r i o d i c a c c e l e r a t e d movements (Waddington 1981). D i f f u s i o n o f heavy i s o t o p e s i n i c e a l t e r s i s o t o p i c c o m p o s i t i o n s b ut c h a n g e s a r e n e g l i g i b l e o v e r s h o r t t i m e p e r i o d s ( l e s s t h a n 1000 y e a r s ) . In t h e s u r g i n g g l a c i e r s t h a t I s t u d i e d , t h e r e s i d e n c e t i m e o f i c e i s p r o b a b l y l e s s t h a n 300 y e a r s and t h i s d i f f u s i o n p r o c e s s c an be i g n o r e d . 28 1.3.5 BASAL ICE EVOLUTION I have s u g g e s t e d t h r e e p r o c e s s e s f o r i n c o r p o r a t i o n o f b a s a l i c e : t h r u s t i n g , r e g e l a t i o n and i c e s e g r e g a t i o n . T h r u s t i n g i s u s u a l l y r e j e c t e d a s a p r o c e s s t h a t c o u l d i n c o r p o r a t e t h e r e g u l a r and e x t e n s i v e d e b r i s s e q u e n c e s t h a t a r e o b s e r v e d i n many g l a c i e r s ( a l t h o u g h i t may be r e s p o n s i b l e f o r some d e b r i s l a y e r i n c o r p o r a t i o n ) . B e c a u se o f t h e c h a r a c t e r i s t i c s of s u b s t r a t e , b a s a l w ater a n d i c e , t h e f r e e z i n g mechanisms o f r e g e l a t i o n and i c e s e g r e g a t i o n w i l l be co m p l e x . The i s o t o p i c f r a c t i o n a t i o n s a s s o c i a t e d w i t h b a s a l f r e e z i n g p r o c e s s e s and v a r i a t i o n s i n t h e i s o t o p i c c o m p o s i t i o n of i n p u t water ( m i x i n g p r o c e s s e s ) w i l l a f f e c t t h e h e a v y i s o t o p e r e l a t i o n s h i p and t h e s t r a t i g r a p h y of b a s a l i c e . 1.3.5.1 M i x i n g P r o c e s s e s B e c a u s e w i n t e r r u n o f f i s m a i n l y s u s t a i n e d by b a s a l i c e m e l t and s t o r e d s u r f a c e m e l t , i t t e n d s t o be i s o t o p i c a l l y c o n s t a n t and h e a v i e r t h a n t h e a v e r a g e l o c a l p r e c i p i t a t i o n ( B e h r e n s e t a l . 1979; Ambach e t a l . 1976). M e l t of l i g h t w i n t e r p r e c i p i t a t i o n c a u s e s s p r i n g r u n o f f t o be l i g h t , b u t summer p r e c i p i t a t i o n and m e l t i n g of t h e h e a v i e r snowpack i n c r e a s e 5 v a l u e s as t h e m e l t s e a s o n p r o g r e s s e s . S i n c e s u r f a c e and s u b g l a c i a l w ater s y s t e m s a r e o f t e n c o n n e c t e d , a s i m i l a r v a r i a t i o n c a n be e x p e c t e d a t t h e g l a c i e r bed. I f b a s a l f r e e z i n g i n c o r p o r a t e s i c e by r e g e l a t i o n and i c e s e g r e g a t i o n , m i x i n g p r o c e s s e s c a n a l t e r t h e i s o t o p i c s t r a t i g r a p h y o f b a s a l i c e . Thus i s o t o p i c v a r i a t i o n s may depend upon t i m e and p o s i t i o n ( l o n g i t u d i n a l and t r a n s v e r s e ) . 29 1.3.5.2 F r e e z i n g P r o c e s s e s J o u z e l and Souchez (1982) f o u n d t h a t s l o p e s o f t h e heavy i s o t o p e r e l a t i o n s h i p s o f b a s a l i c e were l e s s t h a n t h o s e o f b u l k i c e : b a s a l i c e of t h e A r c t i c A k t i n e q G l a c i e r had a s l o p e of 4.9. ( o n l y a few s a m p l e s ) compared t o 7.8 f o r b u l k i c e s a m p l e s ; b a s a l i c e of t h e A l p i n e T s a n f l e u r o n G l a c i e r had a s l o p e of 6.4 compared t o t h e b u l k i c e s l o p e of 8.2. From t h e i r c l o s e d s y s t e m t h e o r e t i c a l model ( S e c t i o n 1.3.2.2) and an a s s u m p t i o n t h a t t h e o r i g i n a l w a t e r 5 v a l u e s were g i v e n by t h e i n t e r s e c t i o n o f t h e b a s a l and b u l k i c e l i n e s , t h e y c a l c u l a t e d s l o p e s t h a t were s i m i l a r b u t l o w e r t h a n t h e measured v a l u e s . They c a l c u l a t e d 5 v a l u e s as a f u n c t i o n o f t h e f r o z e n f r a c t i o n and t h e i n i t i a l i s o t o p i c c o m p o s i t i o n . I c e has a h i g h e r 6 v a l u e t h a n w a t e r from w h i c h i t f o r m s , and as f r e e z i n g p r o g r e s s e s , i c e and r e s i d u a l w ater become p r o g r e s s i v e l y d e p l e t e d i n heavy i s o t o p e s . E a r l y e n r i c h e d f r a c t i o n s of i c e s h o u l d p l o t t o t h e r i g h t of m e t e o r i c or b u l k s a m p l e s ( t h e s o u r c e w a t e r ) , and l a t e r f r a c t i o n s t o t h e l e f t on a 6 D / 5 0 1 8 g r a p h . B o u l t o n (1983) h y p o t h e s i z e d an i s o t o p i c s e q u e n c e i n w h i c h t h e i s o t o p i c r a t i o s a r e h e a v i e s t a t t h e u p - g l a c i e r end of a f r e e z i n g z o n e . T h i s p r e d i c t i o n s u g g e s t s t h a t t h e s u b g l a c i a l water becomes p r o g r e s s i v e l y l i g h t e r as i t f l o w s d o w n - g l a c i e r . Gow e t a l . (1979) measured b a s a l m e l t w a t e r a t t h e t e r m i n u s o f t h e A n t a r c t i c i c e s h e e t w h i c h was d e p l e t e d 3 ° / 0 o i n 5 0 1 8 compared t o b a s a l i c e v a l u e s . In a 4.83 m d e b r i s s e q u e n c e from t h e b a s e o f an A n t a r c t i c d r i l l c o r e , t h e y f o u n d t h a t 6 0 1 8 v a l u e s d i d n o t show an i n c r e a s i n g t r e n d w i t h h e i g h t above t h e bed and were s i m i l a r t o 30 b u l k i c e v a l u e s , a l t h o u g h t h e y v a r i e d by 8 ° / 0 o compared t o 4 ° / 0 0 f o r b u l k i c e . Lawson and K u l l a (1978) a t t r i b u t e d a 5 0 1 8 s h i f t of +4°/oo between l i g h t e r b u l k i c e and h e a v i e r d e b r i s l a d e n i c e i n t h e M a t a n u s k a G l a c i e r , t o r e g e l a t i o n p r o c e s s e s . T h e s e s t u d i e s d i d not c o n t i n u o u s l y sample t h e i s o t o p i c s t r a t i g r a p h y . M i c h e l and F r i t z (1982) o b s e r v e d c o n s t a n t i s o t o p i c c o m p o s i t i o n s i n p e r m a f r o s t c o r e s f r o m a d r a i n e d l a k e bed and s u g g e s t e d t h a t t h e i c e had f r o z e n i n s i t u . T h e i r (1981) p a p e r n o t e d 6 s h i f t s i n p e r m a f r o s t c o r e s f r o m p i n g o s and s e q u e n c e s of m i x e d i c e l e n s e s and s o i l . U n f o r t u n a t e l y t h e y d i d n o t i d e n t i f y c o n t i n u o u s t r e n d s by d e n s e l y s a m p l i n g t h e i c e l a y e r s , a l t h o u g h t h e y o b s e r v e d h e a v i e r i s o t o p e v a l u e s i n two d e b r i s l a y e r s i n p i n g o i c e . L o r r a i n and Demeur (1985) c a l c u l a t e d a h e a v y i s o t o p e s l o p e o f 6.3 f o r f r e e z i n g e x p e r i m e n t s ( M i c h e l 1982), w h i c h compared f a v o u r a b l y t o a c l o s e d s y s t e m s l o p e o f 6.25 d e t e r m i n e d f r om t h e J o u z e l and S ouchez (1982) m o d e l . B e c a u s e M i c h e l ' s i n i t i a l w a t e r was homogeneous t h e J o u z e l and Souchez (1982) model s h o u l d g i v e r e a s o n a b l e r e s u l t s . L o r r a i n and Demeur (1985) examined m a s s i v e g r o u n d i c e from t h e A r c t i c and f o u n d a s l o p e of 7.5 f r o m d e b r i s - l a d e n i c e . They u s e d t h e a v e r a g e o f t h e i r i s o t o p e r e s u l t s a s t h e i n i t i a l 8 v a l u e and d e t e r m i n e d an open s y s t e m s l o p e o f 5.5. From t h e d i s c r e p a n c y , t h e y c o n c l u d e d t h a t t h e i c e was of p r e c i p i t a t e d g l a c i a l o r i g i n n o t s e g r e g a t e d . 1 The open s y s t e m s l o p e model from Souchez and J o u z e l (1984) g i v e s s l o p e v a l u e s t h a t a r e h i g h e r t h a n t h e c l o s e d s y s t e m . These h i g h e r s l o p e s a r e c l o s e r t o t h e s l o p e s measured i n b a s a l i c e . The 1 T h e r e i s a c o n t r o v e r s y whether A r c t i c m a s s i v e i c e i s b u r i e d g l a c i a l i c e o r s e g r e g a t e d i c e . 31 l i m i t a t i o n of b o t h m o d e l s i s t h e a s s u m p t i o n t h a t t h e i n i t i a l 6 v a l u e s do not change ( i . e . t h e i s o t o p i c c o m p o s i t i o n o f i n p u t t o t h e open s y s t e m does n o t c h a n g e ) . The i n p u t v a l u e s c o u l d change due t o m i x i n g w i t h s u r f a c e w a t e r o r a s h i f t i n t h e m e l t i n g / f r e e z i n g z o n e . S o u c h e z and De G r o o t e (1985) c o n s i d e r a v a r i a b l e i s o t o p i c r e s e r v o i r and t h e e f f e c t s on t h e s l o p e . By v a r y i n g t h e i n p u t r e s e r v o i r c o m p o s i t i o n t h e y o b t a i n e d s l o p e s t h a t a r e g r e a t e r t h a n f r e e z i n g s l o p e s . They s u g g e s t t h a t i n g l a c i e r s w h i c h can have an i s o t o p i c a l l y v a r i a b l e b a s a l water s u p p l y , t h e s l o p e f o r b a s a l i c e may a p p r o a c h t h e b u l k i c e s l o p e . S o i l f r e e z i n g p r o c e s s e s may have a f r a c t i o n a t i o n e f f e c t due t o u l t r a f i l t r a t i o n i n t h e a d s o r b e d f i l m l a y e r . T h e o r i e s of i c e s e g r e g a t i o n i n f r e e z i n g s o i l s p o s t u l a t e t h a t w ater moves t h r o u g h a f r o z e n s o i l f r i n g e t o f r e e z e on t o an i c e l e n s . A slow f r e e z i n g p r o c e s s m i g h t have an i c e / w a t e r f r a c t i o n a t i o n c ombined w i t h an a d s o r p t i o n f r a c t i o n a t i o n , e i t h e r of w h i c h c o u l d d o m i n a t e . P r e v i o u s s o i l s t u d i e s have n o t c o n s i d e r e d t h e i s o t o p i c e f f e c t s o f s u r f a c e f o r c e s i n f r o z e n and u n f r o z e n s o i l s . G r o u n d w a t e r r e c h a r g e r e s e a r c h h as i d e n t i f i e d f r a c t i o n a t i o n e f f e c t s b u t t h e s e s h i f t s i n 5 a r e g e n e r a l l y a t t r i b u t e d t o e v a p o t r a n s p i r a t i o n and o t h e r r e c h a r g e phenomena (Gat and T z u r 1967; Zimmerman e t a l . 1967; Gat 1981). M i c h e l and F r i t z (1981) m e a s u r e d 6 s h i f t s f o r d e u t e r i u m and O 1 8 i n l a b o r a t o r y f r e e z i n g e x p e r i m e n t s i n s i l t and s a n d . The s h i f t s between t h e f r o z e n and u n f r o z e n z o n e s o c c u r r e d d u r i n g p e r i o d s when t h e f r e e z i n g f r o n t was s t a b i l i z e d , b u t t h e m a g n i t u d e s were o n l y h a l f t h e t h e o r e t i c a l 32 f r e e z i n g s h i f t s . The s a m p l e s were m e c h a n i c a l l y s q u e e z e d from s o i l s e c t i o n s . B e c a u s e t h e r e was v e r y l i t t l e i c e l e n s i n g , i s o t o p i c e f f e c t s a r i s i n g f r o m movement of w a t e r t h r o u g h a f r o z e n f r i n g e c a n n o t be c o n s i d e r e d from t h e i r r e s u l t s . F i e l d r e s u l t s from p i n g o i c e s a m p l e d i n t h i s s t u d y were i n t e r e s t i n g f o r two d e b r i s l a y e r s w h i c h c o n t a i n e d >50% s e d i m e n t . B o t h l a y e r s had i c e t h a t was h e a v i e r i n 6 0 1 8 , one l a y e r by 5 ° / 0 0 and t h e s e c o n d by 3°/oo- The p i n g o i c e c o r e s c o n t a i n e d d i f f e r e n t c o n c e n t r a t i o n s o f s e d i m e n t w h i c h i m p l i e s t h a t a p r o c e s s of i c e s e g r e g a t i o n was a c t i v e . In a l a t e r s t u d y of f r e e z i n g i n a n e w l y - d r a i n e d l a k e bed, o n l y a few i s o t o p i c s h i f t s were measured ( M i c h e l and F r i t z 1982). T h e s e s h i f t s were a t t r i b u t e d t o p e r i o d s o f slow f r e e z i n g w h i c h a l l o w e d f r a c t i o n a t i o n t o o c c u r . 1.4 SUMMARY The p u r p o s e o f my r e s e a r c h i s t o d e t e r m i n e t h e mechanisms o f a c c r e t i o n of d e b r i s and i c e l a y e r s i n s u r g i n g g l a c i e r s . B e c a u s e t h e a c c r e t i o n mechanisms a f f e c t t h e i s o t o p i c p r o p e r t i e s o f b a s a l i c e , I c a n use i s o t o p i c methods t o i n f e r t h e a c t i v e p r o c e s s e s . The i s o t o p i c c h a r a c t e r i s t i c s a l s o depend upon t h e m i x i n g p r o c e s s e s t h a t s u p p l y t h e b a s a l w a t e r s y s t e m . In F i g u r e 7, I have i n c o r p o r a t e d f r a c t i o n a t i o n p r o c e s s e s i n t o t h e framework o f water c i r c u l a t i o n i n a g l a c i a l s y s t e m , o r i g i n a l l y i l l u s t r a t e d i n F i g u r e 6. B u l k i c e i s i n f l u e n c e d i s o t o p i c a l l y by e v a p o r a t i o n and s u b l i m a t i o n mechanisms, and by p e r c o l a t i o n p r o c e s s e s i n v o l v e d i n e v o l u t i o n o f t h e snowpack. The r e s u l t s o f b u l k i c e a n a l y s e s c a n be compared t o m e t e o r i c r e s u l t s t o measure t h e d e g r e e o f 33 f r a c t i o n a t i o n . B a s a l i c e and d e b r i s i n c o r p o r a t i o n i s a more complex p r o b l e m . B a s a l i c e i s i n f l u e n c e d by m i x i n g , f r a c t i o n a t i o n , and g l a c i a l f r e e z i n g p r o c e s s e s . To d e t e r m i n e t h e r o l e s o f t h e d i f f e r e n t p r o c e s s e s I w i l l c o n t r a s t b u l k and b a s a l i c e and d e b r i s c h a r a c t e r i s t i c s by u s i n g : 1. I s o t o p i c a n a l y s e s (a) Heavy i s o t o p e r e l a t i o n s h i p (b) I s o t o p i c s t r a t i g r a p h y . 2. A s s o c i a t e d w ater q u a l i t y and i c e and d e b r i s f a b r i c a n a l y s e s . 34 F i g u r e 7. F r a c t i o n a t i o n p r o c e s s e s i n a g l a c i a l s y s t e m . D u r i n g e a c h s t e p i n t h e movement of water t h r o u g h a g l a c i a l s y stem, t h e f r a c t i o n a t i o n s l i s t e d i n t h e r i g h t column c a n o c c u r . RAIN ENGLACIAL WATER BASAL DISCHARGE GLOBAL RESERVOIR ocean water f r e s h , w a t e r ATMOSPHERIC WATER SNOW SNOW LAYERS snow i n t e r s t i t i a l w a t er FIRN s t o r e d w a t e r f i r n SUBSTRATE WATER basal waler surface wal er BASAL ICE X Fracti onation Processes Meteoric e v a p o r a t i o n Mel eori c c o n d e n s a t i o n s u b l i m a t i o n Snow Evolution s u b l i m a t i o n e v a p o r a t i o n c o n d e n s a t i o n Snow Evolution m e l t / f r e e z e Mi xi ng Mixi ng Basal Ice Evolution m e l t / f r e e z e i c e s e g r e g a t i o n BULK ICE Substrate Circulation SAMPLING Sample Averaging C h a p t e r 2 METHODS The aims o f t h e f i e l d and l a b o r a t o r y r e s e a r c h were: 1. To d i s t i n g u i s h c h a r a c t e r i s t i c s of b u l k and b a s a l i c e . 2. To i d e n t i f y p r o c e s s e s f r o m t h e s e d i f f e r e n c e s and t h e i s o t o p i c s t r a t i g r a p h y and h e a v y i s o t o p e r e l a t i o n s h i p . 3. To c h a r a c t e r i z e t h e d e b r i s s e q u e n c e s . I c o n c e n t r a t e d on i s o t o p i c a n a l y s e s t o a c h i e v e t h e s e a i m s , a l t h o u g h c h e m i c a l and s e d i m e n t a n a l y s e s were a l s o done on some s a m p l e s . In t h i s c h a p t e r , I o u t l i n e f i e l d and l a b o r a t o r y methods. 2.1 FIELDWORK E x p o s u r e s of b a s a l i c e a l o n g m a r g i n a l f a c e s and t u n n e l s o f Backe and T r a p r i d g e G l a c i e r s p e r m i t t e d s a m p l i n g o f t h e e x t e n s i v e d e b r i s s e q u e n c e s . The f i e l d w o r k c o n s i s t e d o f two major p h a s e s : a p r e l i m i n a r y s t u d y t o d e t e r m i n e c h a r a c t e r i s t i c s o f t h e i c e , and an i n t e n s i v e s t u d y o f s e l e c t e d f e a t u r e s on t h e two g l a c i e r s . S u b s e q u e n t l y , s a m p l e s were t a k e n t o p r o v i d e a d d i t i o n a l i n f o r m a t i o n a b o u t c e r t a i n of t h e s e c h a r a c t e r i s t i c s . B e c a u s e d i f f u s i o n and c o n t a m i n a t i o n c a n a f f e c t t h e i s o t o p i c c o m p o s i t i o n of e x p o s e d i c e l a y e r s , I removed t h e o u t e r 20-30 cm o f i c e a t e a c h s i t e . I u s e d two methods f o r o b t a i n i n g s a m p l e s : 1. As a c l e a n i c e screw was r o t a t e d i n t o t h e g l a c i e r , i c e and snow c h i p s were c o l l e c t e d d i r e c t l y i n t o a 60 ml N a l g e n e b o t t l e . T h i s method was u s e d d u r i n g t h e p r e l i m i n a r y work i n 1981, and d u r i n g s u b s e q u e n t s p o t s a m p l i n g i n 1983 and 1984. 35 36 2. A c h a i n saw was u s e d t o c u t a wedge-shaped c o r e f r o m 20-50 cm l o n g . T h i s c o r e was t h e n c u t i n t o 1-5 cm p i e c e s and p a c k e d i n t o 60 ml N a l g e n e b o t t l e s . I n summer o f 1982, I u s e d t h i s method t o c u t and sample a s e t o f f i e l d c o r e s . The N a l g e n e b o t t l e s were s e a l e d u s i n g p a r a f f i n a s an add e d p r e c a u t i o n , a l t h o u g h s u b s e q u e n t r e s u l t s have shown t h i s s t e p t o be u n n e c e s s a r y . I a l s o removed a d u p l i c a t e s e t o f c o r e s ( w i t h i n 0.20 m o f t h e i n i t i a l c o r e s ) w h i c h I was a b l e t o r e t u r n i n t a c t t o V a n c o u v e r . The i n t a c t c o r e s have been c u t i n t h e s t e r i l e e n v i r o n m e n t o f a c o l d room and p a c k e d i n t o 60 ml g l a s s o r N a l g e n e b o t t l e s . A l l of t h e f i e l d s a mples were f r o z e n w i t h i n two weeks o f r e m o v a l and have r e m a i n e d f r o z e n e x c e p t f o r s h o r t p e r i o d s d u r i n g a n a l y s e s . The i c e was a l w a y s h a n d l e d u s i n g v i n y l or p l a s t i c g l o v e s . The s a m p l i n g s i t e s a r e shown i n F i g u r e 8. In t h e summer of 1981, I s a m p l e d a l o n g i t u d i n a l p r o f i l e a l o n g t h e T r a p r i d g e s u r f a c e from s t a k e 9 above t h e b u l g e t o s t a k e A i n t h e l o w e r s t a g n a n t zone, and a l o n g t h r e e p r o f i l e s i n a m e l t w a t e r t u n n e l t h r o u g h a d e b r i s - l a d e n s e c t i o n of i c e i n t h e l e f t l o w e r s t a g n a n t z o n e . T h i s s e m i c i r c u l a r t u n n e l i s a p p r o x i m a t e l y 100 m l o n g w i t h an e n t r a n c e r a d i u s o f 5 m and an e x i t r a d i u s of 2 m ( s e e F i g u r e 1 ) . I removed i c e from p o i n t s 20 t o 50 cm a p a r t a r o u n d t h e c i r c u m f e r e n c e ; one p r o f i l e n e a r t h e e n t r a n c e , one i n t h e m i d d l e , and t h e o t h e r , 15 m i n from t h e e x i t . Ten s a m p l e s , w h i c h i n c l u d e d b u l k and b a s a l i c e , were a l s o removed from a f a c e on t h e l o w e r r i g h t s t a g n a n t i c e ( S i t e TRF1 i n 37 F i g u r e 8 . Sample s i t e s on T r a p r i d g e and Backe G l a c i e r s . Numbers and l e t t e r s g i v e t h e a p p r o x i m a t e l o c a t i o n s o f s u r v e y s t a k e s . O t h e r s u r v e y s t a k e s t h a t a r e r e f e r e n c e d i n t h e t h e s i s a r e l o c a t e d i n o r d e r between a p p r o p r i a t e numbers o r l e t t e r s . Margin 38 F i g u r e 8 ) . In 1982, I c h a i n - s a w c o r e d a t 5 s i t e s on T r a p r i d g e G l a c i e r and one s i t e on Backe G l a c i e r t o o b t a i n b u l k and b a s a l i c e s a m p l e s . A l l c o r e s were v e r t i c a l and t o t a l c o r e l e n g t h a t e a c h s i t e v a r i e d from 45-200 cm; two s e t s o f p a r a l l e l c o r e s were removed as d i s c u s s e d a b o v e . A f t e r t h e i c e s t r u c t u r e was r e c o r d e d , one c o r e from e a c h s i t e was c o n t i n u o u s l y s a m p l e d i n 2-5 cm s l i c e s . The s e c o n d c o r e was r e t u r n e d t o a c o l d room where t h e o u t e r s u r f a c e s o f t h e c o r e were trimmed t o remove c o n t a m i n a t i o n , and i n d i v i d u a l i c e l a y e r s were c o n t i n u o u s l y s a m p l e d . The r e s u l t s o f i s o t o p i c a n a l y s e s on t h e two s e t s of s a m p l e s a r e i n most c a s e s t h e same w i t h i n measurement u n c e r t a i n t y , w h i c h s u g g e s t s t h a t t h e f i e l d methods a r e n o n - c o n t a m i n a t i n g . In 1983 and 1984, I s u p p l e m e n t e d t h e 1982 c o r e s a m p l i n g t o o b t a i n a w i d e r r a n g e o f f r e s h p r e c i p i t a t i o n , m e l t w a t e r and b u l k i c e . In t o t a l , 435 s a m p l e s were a n a l y z e d f o r i s o t o p i c p r o p e r t i e s . I s e l e c t e d t h e 1982 s i t e s t o f u r t h e r c h a r a c t e r i z e i s o t o p i c p r o p e r t i e s and examine v a r i o u s f e a t u r e s o f Backe and T r a p r i d g e G l a c i e r s . A l t h o u g h a s t e e p f a c e on Backe G l a c i e r p a r t i a l l y r e s t r i c t e d s e l e c t i o n o f a s i t e , t h e major c r i t e r i o n was t o s e l e c t a l o c a t i o n where t h e d e b r i s l a y e r s had not been f o l d e d . I removed a 2.20 m c o r e from t h e v e r t i c a l Backe f a c e (BA1) a p p r o x i m a t e l y 10 m above g r o u n d m o r a i n e and an a c c u m u l a t i o n o f w i n t e r snow and i c e a t t h e g l a c i e r f r o n t . I a l s o c u t a 1.00 m c o r e (BA2) from 2 m above BA1, t o c h a r a c t e r i z e i s o t o p i c c h a n g e s w i t h h e i g h t above t h e b e d . I s a m p l e d Backe b u l k i c e from s i t e s on t h e s u r f a c e o f t h e g l a c i e r above t h e b a s a l d e b r i s l a y e r s . 39 T r a p r i d g e b a s a l i c e came from two main l o c a t i o n s , TRC1 (Cave 1 ) , and TRB2 (Base 2 ) . D e b r i s s e q u e n c e s a t t h e s e two s i t e s a r e t y p i c a l o f b a s a l z o n e s and s i m i l a r t o t h e Backe s i t e s . A t o t a l of 1.87 m and 1.00 m were removed r e s p e c t i v e l y . I a l s o c u t a 1.00 m c o r e and a 0.45 m c o r e , f r o m two T r a p r i d g e b a s a l s i t e s t h a t d i d no t have t h i c k d e b r i s s e q u e n c e s , TRC2 (Cave 2) and TRB1 (Base 1 ) . The TRC2 c o r e was t a k e n from g r o u n d m o r a i n e up i n t o g l a c i e r i c e i n a c e n t r a l m e l t w a t e r t u n n e l t h a t d i d n o t have b a s a l d e b r i s l a y e r s . The TRB1 s i t e had a s i n g l e d e b r i s l a y e r above t h e c o r e h o l e . The T r a p r i d g e b u l k i c e samples were m a i n l y f r o m a 1.00 m c o r e on t o p o f t h e b u l g e n e a r S t a k e 8 ( T R S T 8 ) . The 1981 s u r f a c e p r o f i l e (TR81) was c o l l e c t e d t o examine g e n e r a l c h a r a c t e r i s t i c s of T r a p r i d g e i s o t o p i c h i s t o r y , i n c l u d i n g a l t i t u d e e f f e c t s . The 1981 s a m p l e s a l o n g t h e m e l t w a t e r t u n n e l were a l s o t a k e n t o i d e n t i f y l o n g i t u d i n a l i s o t o p i c v a r i a t i o n s w h i c h m i g h t r e f l e c t a l t i t u d e e f f e c t s . 2.2 OXYGEN ISOTOPES I have a n a l y z e d t h e O 1 8 c o m p o s i t i o n s o f t h e samp l e s i n t h e Department o f G e o p h y s i c s and Astronomy I s o t o p e L a b o r a t o r y a t t h e 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 . The UBC s y s t e m c o n s i s t s o f a f u l l y a u t o m a t e d c a r b o n d i o x i d e e q u i l i b r a t i o n l i n e ( Whaite 1982) and a c o n v e r t e d l e a d i s o t o p e mass s p e c t r o m e t e r w i t h h i g h r e s o l u t i o n d o u b l e c o l l e c t o r s ( A h e r n 1975 and 1980). The main f e a t u r e s o f t h e UBC s y s t e m i n c l u d e : 1. E l i m i n a t i o n of t i m e c o n s u m i n g o p e r a t o r i n t e r a c t i o n s 40 i n f a v o u r of a u t o m a t i o n . The a u t o m a t i c s t e p s i n c l u d e d i s s o l v e d gas r e m o v a l t h r o u g h use o f a s y m m e t r i c a l pumping c o n f i g u r a t i o n t o 16 sample t u b e s . 2. E l i m i n a t i o n o f n e c e s s i t y f o r p r e c i s e t e m p e r a t u r e c o n t r o l t h r o u g h s i m u l t a n e o u s i s o l a t i o n o f 16 e q u i l i b r a t e d s a m p l e s . 3. E l i m i n a t i o n o f mass-45 c o r r e c t i o n s b e c a u s e of t h e h i g h r e s o l u t i o n o f t h e c o n v e r t e d l e a d i s o t o p e mass s p e c t r o m e t e r . Samples of w a t e r , u s u a l l y 5 ml e a c h of 12 unknowns and f o u r l a b s t a n d a r d s , a r e i n t r o d u c e d t o t h e e q u i l i b r a t i o n r a c k and d i s s o l v e d g a s e s a r e pumped away. A f t e r c a r b o n d i o x i d e e q u i l i b r a t e s w i t h t h e sample f o r 14 h, t h e gas i s i n t r o d u c e d t o t h e mass s p e c t r o m e t e r . The e q u i l i b r a t e d g a s e s a r e i o n i z e d and a c c e l e r a t e d t h r o u g h a m a g n e t i c f i e l d t o s t r i k e two c o l l e c t i n g c u p s , t h a t measure t h e i o n c u r r e n t s f o r m o l e c u l a r w e i g h t s 44 and 46. The S O 1 8 i s c a l c u l a t e d f r o m an a v e r a g e of t h e r e l a t i v e s t r e n g t h s o f t h e i o n c u r r e n t s and r e l a t e d t o VSMOW u s i n g t h e r e s u l t s o f t h e f o u r s t a n d a r d s . In i t s c u r r e n t c o n f i g u r a t i o n , t h e UBC i s o t o p e s y s t e m has been u s e d f o r r o u t i n e oxygen i s o t o p e a n a l y s e s f o r o v e r f i v e y e a r s . In my s t u d y t h e a v e r a g e i n t e r n a l r e p r o d u c i b i l i t y i s a p p r o x i m a t e l y ± 0 . 1 0 ° / o o r a t one s t a n d a r d d e v i a t i o n , a l t h o u g h t h e p r a c t i c a l e r r o r i n c l u d i n g s a m p l i n g and sample p r e p a r a t i o n i s c l o s e r t o ± 0 . 2 0 ° / o o « T h i s a c c u r a c y i s c o m p a r a b l e t o o t h e r w o r l d l a b o r a t o r i e s . I n d e p e n d e n t a n a l y s e s o f two s a m p l e s a t t h e U n i v e r s i t y o f A l b e r t a (UA) Mass S p e c t r o m e t r y L a b o r a t o r y were i n agreement w i t h measurements on t h e UBC s y s t e m 41 w i t h i n u n c e r t a i n t i e s (S160 was - 1 7 . 0 0 ° / o o - a t UBC, - 1 6 . 9 0 ° / o o a t UA, and LTW3 was - 1 6 . 8 7 ° / 0 0 a t UBC, - 1 6 . 7 0 ° / o o a t UA). The r e s u l t s a r e r e c o r d e d i n C h a p t e r 3. 2.3 HYDROGEN ISOTOPES I a n a l y z e d t h e d e u t e r i u m c o n c e n t r a t i o n s o f t h e samples i n t h e D e p a r t m e n t o f P h y s i c s Mass S p e c t r o m e t r y L a b o r a t o r y of t h e U n i v e r s i t y o f A l b e r t a . The U n i v e r s i t y of A l b e r t a s y s t e m c o n s i s t s of a s t a n d a r d u r a n i u m l i n e w i t h T o e p l e r Pump e x t r a c t i o n o f h y d r o g e n a n d a c o m m e r c i a l M i c r o m a s s 602C w i t h d i a l l e d c o r r e c t i o n s f o r H 3 + . A 15 t o 20 /ul wa t e r sample r e a c t s w i t h u r a n i u m m e t a l a t 750 °C, c a u s i n g f o r m a t i o n o f u r a n i u m o x i d e . The h y d r o g e n gas i s c o l l e c t e d i n t o a sample t u b e by a T o e p l e r Pump s y s t e m . In a r u n , I e x t r a c t e d a r e f e r e n c e sample, a s t a n d a r d , 6 t o 10 unknowns and f i n a l l y a s e c o n d s t a n d a r d . The sample t u b e s a r e c o n n e c t e d c o n s e c u t i v e l y t o t h e 602C mass s p e c t r o m e t e r and t h e d e u t e r i u m r a t i o o f e a c h sample v e r s u s t h e r e f e r e n c e gas i s me a s u r e d . The 5D i s r e l a t e d t o VSMOW from t h e r e s u l t s o f t h e two s t a n d a r d s . I n i t i a l l y t h e r e f e r e n c e gas was UBC LTW3 and t h e s t a n d a r d gas was a 1973 sample of NBS-1A, but t h e r e f e r e n c e was l a t e r c h a n g e d t o NBS-1A a n d a 1984 sample of GISP was u s e d a s t h e s t a n d a r d . 1 The i n t e r n a l r e p r o d u c i b i l i t y o f t h e s y s t e m was a p p r o x i m a t e l y ±1.0°/oo a t 1 s t a n d a r d d e v i a t i o n , a l t h o u g h sample p r e p a r a t i o n e r r o r s s u g g e s t an o v e r a l l a c c u r a c y o f ± 2 . 0 ° / o o . T h i s u n c e r t a i n t y i s c o m p a r a b l e t o o t h e r w o r l d l a b o r a t o r i e s . 1 LTW3 i s l a b o r a t o r y t a p w a t e r ; NBS-1A i s an o l d e r s t a n d a r d of t h e U n i t e d S t a t e s N a t i o n a l B u r e a u o f S t a n d a r d s ; GISP i s G r e e n l a n d I c e S h e e t P r e c i p i t a t i o n . 42 2.4 SLOPE CALCULATIONS I p r e s e n t t h e i s o t o p i c r e s u l t s i n two f o r m a t s , t h e i s o t o p i c s t r a t i g r a p h y and t h e heavy i s o t o p e r e l a t i o n s h i p . The g e n e r a l method f o r c h a r a c t e r i z i n g t h e f r e e z i n g p r o c e s s i s t o f i t a s t r a i g h t l i n e t o t h e heavy i s o t o p e r e l a t i o n s h i p . I have d i s c u s s e d t h e c o m p l e x i t i e s o f i s o t o p i c f r a c t i o n a t i o n t h a t c a n c a u s e t h e s t r a i g h t l i n e r e l a t i o n s h i p t o be an i n v a l i d r e p r e s e n t a t i o n o f a b a s a l f r e e z i n g p r o c e s s , however, t h e method c a n be u s e d t o c h a r a c t e r i z e a s e t o f s a m p l e s . When two r e l a t e d v a r i a b l e s have u n c e r t a i n t i e s o f t h e same o r d e r , r e g r e s s i o n s on x o r y a r e n o t v a l i d b e c a u s e o f t h e a s s u m p t i o n o f n e g l i g i b l e e r r o r s i n t h e i n d e p e n d e n t c o o r d i n a t e . Most r e s e a r c h e r s have not r e p o r t e d t h e i r s l o p e c a l c u l a t i o n methods, a l t h o u g h t h e r e d u c e d m a j o r a x i s t e c h n i q u e i s r e p o r t e d i n Y u r t s e v e r and Gat ( 1 9 8 1 ) . A method b a s e d on t h e l e a s t s q u a r e s c u b i c i s s t a t i s t i c a l l y b e t t e r and c a l c u l a t e d s l o p e s can be o v e r 20% d i f f e r e n t f r o m t h e r e g r e s s i o n on x r e s u l t s , and 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 a v e r a g e o f x and y r e g r e s s i o n s and t h e r e d u c e d major a x i s r e s u l t s . R e p o r t e d s l o p e r e s u l t s t h a t were n o t c a l c u l a t e d by t h e l e a s t s q u a r e s c u b i c , o r r e d u c e d m a j o r a x i s a t w o r s t , a r e s u s p e c t and s h o u l d be r e c a l c u l a t e d . In t h i s t h e s i s I c a l c u l a t e d s l o p e s u s i n g r e g r e s s i o n on y, r e g r e s s i o n on x, r e d u c e d m a j o r a x i s and l e a s t s q u a r e s c u b i c . The methods a r e d i s c u s s e d i n Y o r k ( 1 9 6 6 ) , (1967) and ( 1 9 6 9 ) , and W i l l i a m s o n ( 1 9 6 8 ) . I r e p o r t t h e r e s u l t s o f t h e l e a s t s q u a r e s c u b i c a n a l y s e s . Y o r k (1967) g i v e s a s i m p l e e x p l a n a t i o n of t h e d i f f e r e n t a n a l y s i s methods. Reduced ma j o r a x i s e s s e n t i a l l y m i n i m i z e s t h e 43 sum o f t h e s q u a r e s o f t h e d i s t a n c e s f r o m e a c h d a t a p o i n t t o t h e b e s t l i n e , a l o n g a p a t h t h a t i s p e r p e n d i c u l a r t o t h e b e s t l i n e . The x and y r e g r e s s i o n s m i n i m i z e t h e same sums a l o n g p a t h s t h a t a r e p a r a l l e l t o t h e r e s p e c t i v e a x e s . In c o n t r a s t , f i t t i n g by t h e l e a s t s q u a r e s c u b i c m i n i m i z e s t h e sum a l o n g p a t h s t h a t a r e w i t h i n a t r i a n g l e bounded by a h o r i z o n t a l l i n e and v e r t i c a l l i n e c o n n e c t i n g t h e d a t a p o i n t t o t h e b e s t l i n e . The a n g l e o f t h i s p a t h i s d e p e n d e n t upon t h e c h o s e n u n c e r t a i n t i e s f o r e a c h d a t a p o i n t . F o r s l o p e c a l c u l a t i o n s , I a d a p t e d a p r o g r a m from t h e a l g o r i t h m o f W i l l i a m s o n (1968) and R u s s e l l ( p e r s o n a l c o m m u n i c a t i o n ) . The v a r i a n c e s of t h e s l o p e s and i n t e r c e p t s a r e c a l c u l a t e d by two methods, t h a t o f Y o rk (1968) and W i l l i a m s o n ( 1 9 6 8 ) . The York method i s b a s e d on a c a l c u l a t i o n o f t h e maximum and minimum of t h e s l o p e s , w hereas, W i l l i a m s o n recommends a p r o c e d u r e t h a t t a k e s a c c u r a c y of t h e d a t a i n t o c o n s i d e r a t i o n . I o n l y r e p o r t t h e r e s u l t s o f t h e more common York method ( a t t h e 1a l e v e l ) w h i c h was u s u a l l y g r e a t e r t h a n t h e W i l l i a m s ' method. C h a p t e r 3 RESULTS 3.1 GENERAL OBSERVATIONS The b a s a l i c e and d e b r i s l a y e r s of Backe and T r a p r i d g e G l a c i e r s have s i m i l a r c h a r a c t e r i s t i c s , a l t h o u g h some a s p e c t s of t h e i r a p p e a r a n c e s a r e d i f f e r e n t . The Backe G l a c i e r h as d e b r i s l a y e r s t h a t c a n be t r a c e d a c r o s s t h e t e r m i n a l f a c e and a l o n g t h e m a r g i n s o f t h e i c e . The m a r g i n a l s t a g n a n t T r a p r i d g e i c e has b a s a l d e b r i s s e q u e n c e s t h a t a r e s i m i l a r t o t h e Backe s e q u e n c e s , b ut t h e m e l t w a t e r t u n n e l t h r o u g h t h e c e n t r a l s t a g n a n t i c e below t h e b u l g e d i d n o t have d e b r i s l a y e r s i n c o r p o r a t e d i n t o t h e b a s a l i c e . I t i s p o s s i b l e t h a t water f l o w under t h e c e n t r a l i c e d u r i n g a s u r g e c a u s e s t h e d e b r i s l a y e r s t o m e l t . B e c a u s e t h e t u n n e l i s t h e o n l y e x p o s u r e o f c e n t r a l T r a p r i d g e b a s a l i c e , i t i s d i f f i c u l t t o d e t e r m i n e whether i c e t h a t i s away from t h e t u n n e l a r e a c o n t a i n s b a s a l d e b r i s l a y e r s . In a d d i t i o n , t h e e x t e n s i v e f o l d e d s e q u e n c e s of d e b r i s l a y e r s e x p o s e d on some s e c t i o n s of t h e t e r m i n a l f a c e of Backe G l a c i e r a r e not p r e s e n t on T r a p r i d g e . B o t h g l a c i e r s have random f i n e d e b r i s l a y e r s c u t t i n g a c r o s s t h e p a r a l l e l d e b r i s s e q u e n c e s and p a r t i a l l y i n t o b u l k i c e . T h e s e l a y e r s a r e v i s i b l e on t h e m a r g i n a l f a c e s and c o u l d be l a y e r s o f s q u e e z e d f l u i d i z e d s u b s t r a t e . D u r i n g a s u r g e , s h e a r i n g a t t h e b a s e may i n c o r p o r a t e t h i s d e b r i s a l o n g a s h e a r z o n e . 1 D e b r i s i n c o r p o r a t i o n t h r o u g h s h e a r i n g i s p o s s i b l e b u t t h e random n a t u r e o f t h e s e f i n e d e b r i s 1 T h e s e s h e a r f e a t u r e s c a n r e s u l t f r o m d e c e l e r a t i o n o f t h e l o w e r -zone b e f o r e t h e upper g l a c i e r ( J ohn Shaw, p e r s o n a l c o m m u n i c a t i o n ) . 44 45 l a y e r s s u p p o r t s a l t e r n a t e mechanisms f o r a c c r e t i o n o f t h e e x t e n s i v e p a r a l l e l l a y e r s . T h r o u g h o u t t h e a b l a t i o n s e a s o n s of 1980 t o 1985, b o t h g l a c i e r s m a i n t a i n e d o n l y t h i n snow c o v e r s e x c e p t i n t h e h i g h e s t a r e a s o f t h e i r a c c u m u l a t i o n z o n e s ( o v e r 2500 m a . s . l . ) . The g l a c i e r s i n t h i s v a l l e y a r e composed of s i g n i f i c a n t amounts o f s u p e r i m p o s e d i c e . Brewer (1972) o b s e r v e d 25 cm o f s u p e r i m p o s e d i c e a t one s i t e on R u s t y G l a c i e r and West and K r o u s e (1972) a l s o n o t e d t h e s h o r t t i m e f o r e v o l u t i o n o f snow t o i c e i n e x t e n s i v e wet snowpacks t h r o u g h o u t R u s t y G l a c i e r ( S e c t i o n 1.3.4). As t h e b u l g e has moved down T r a p r i d g e G l a c i e r and s u r f a c e s t r e a m s have c u t i n t o t h e i c e , t h e s u r f a c e has become i n c r e a s i n g l y c r e v a s s e d . E v o l u t i o n o f t h e b u l g e and t r a n s i t i o n of a f r o z e n b a s a l zone t o a warm bed i s a p p a r e n t i n t h e summary of s u r v e y and t e m p e r a t u r e measurements i l l u s t r a t e d i n F i g u r e 4 (and d i s c u s s e d e a r l i e r i n S e c t i o n 1.2.1). In c o n t r a s t t o t h e e f f e c t s o f t h e a p p r o a c h i n g s u r g e o f T r a p r i d g e , t h e Backe s u r f a c e has become l e s s c r e v a s s e d s i n c e i t s s u r g e , b e c a u s e o f m e l t i n g , and c r e v a s s e c l o s u r e and f i l l i n g . Oxygen i s o t o p e a n a l y s e s of p r e l i m i n a r y samples i n 1981 i n d i c a t e d t h a t T r a p r i d g e does n o t have a s i m p l e i s o t o p i c p a t t e r n . The i s o t o p i c s u r f a c e p r o f i l e a c r o s s t h e b u l g e and down t o t h e end o f t h e s t a g n a n t i c e d i d n o t show a c o n s i s t e n t v a r i a t i o n ( F i g u r e 9 ) . A l t h o u g h e a c h s i t e was s a m p l e d t w i c e w i t h i n a 1 m d i s t a n c e , s e v e r a l o f t h e p a i r s v a r i e d by up t o 3°/oo« S i n c e t h e r e was no s i m p l e a l t i t u d e e f f e c t a l o n g t h e p r o f i l e , t h e 1981 v a r i a t i o n s may i n d i c a t e s a m p l i n g of b u l k i c e and s u p e r i m p o s e d i c e . The heavy 46 F i g u r e 9 . TR81 i s o t o p i c s u r f a c e p r o f i l e . The i s o t o p i c c o m p o s i t i o n s of two s a m p l i n g s a t e a c h s u r f a c e s i t e a r e p l o t t e d ( w i t h l a u n c e r t a i n t i e s ) v e r s u s t h e a l t i t u d e a t e a c h s i t e ( S i t e E has d u p l i c a t e v a l u e s ) . T h e r e i s no c o n s i s t e n t i s o t o p i c p a t t e r n of change w i t h a l t i t u d e ( o r l e n g t h ) on t h e T r a p r i d g e G l a c i e r . S i t e s 7C t o 9C were above t h e b u l g e , B t o 3C below t h e b u l g e , and 4C t o 6.5C were on t h e b u l g e . The l a r g e d i f f e r e n c e s a t some s t a t i o n s may i n d i c a t e s a m p l i n g of b u l k a n d / o r s u p e r i m p o s e d i c e w h i c h has been a f f e c t e d by r e c e n t snow and i c e e v o l u t i o n p r o c e s s e s . U n c e r t a i n t i e s a r e i n d i c a t e d by t h e l e n g t h of t h e l i n e s . 2350 2300 -2250 2200 2150 -2100 2050 -32.0 -26.0 -22.0 6 0 " ( ° / o o ) 47 i s o t o p e , r e l a t i o n s h i p r e v e a l e d a c h a r a c t e r i s t i c s l o p e o f 5.79 ±0.40 ( F i g u r e 10) t h a t i s c o m p a r a b l e t o t h e 5.75 r e s u l t o f Moser and S t i c h l e r (1975) f o r s u b l i m a t i n g snow a t -10 °C. Some o f t h e s a m p l e s may be s u p e r i m p o s e d i c e w h i c h has u n d e r g o n e e v a p o r a t i o n / s u b l i m a t i o n f r a c t i o n a t i o n or p e r c o l a t i o n e x c h a n g e . A m i x e d s e t o f b u l k i c e t h a t has been formed a t h i g h e r a l t i t u d e and r e c e n t s u p e r i m p o s e d i c e may c a u s e t h e s c a t t e r on t h e g r a p h . The a v e r a g e s of 6 v a l u e s from t h r e e s i t e s a l o n g t h e t u n n e l , TRC1, a t a p p r o x i m a t e l y 50 m s p a c i n g s , d i d n o t have a c o n s i s t e n t v a r i a t i o n w i t h l o n g i t u d i n a l d i s t a n c e ( t u n n e l e n t r a n c e : - 2 5 . 9 4 ° / 0 o f o r 10 s a m p l e s ; m i d d l e : - 2 6 . 5 0 ° / o o f o r 13 s a m p l e s ; t u n n e l e x i t : - 2 6 . l 7 ° / 0 0 f o r 9 s a m p l e s ) . A s e t o f 10 s a m p l e s from a 5 m m a r g i n a l f a c e i n t h e T r a p r i d g e s t a g n a n t zone d i d n o t show a c o n s i s t e n t change i n 6 v a l u e s w i t h h e i g h t above t h e b e d . In a d d i t i o n 1982 samples o f 1 m of i c e from TRC1 had no s i g n i f i c a n t i s o t o p i c change from t o p t o b o t t o m . Backe G l a c i e r b a s a l l a y e r s showed a s h i f t o f - 2 ° / 0 0 i n 8 0 1 8 i n a c o m p a r i s o n of t h e a v e r a g e o f l o w e r p o s i t i o n BA1 s a m p l e s t o t h e h i g h e r BA2 samples (5 m of i c e s e p a r a t i o n ) . The BA1 s a m p l e s d i d have a w i d e r r a n g e t h a n t h e BA2 s a m p l e s and t h e d i f f e r e n c e i n t h e a v e r a g e s may r e f l e c t t h e s a m p l i n g , n o t a r e l a t i o n s h i p between h e i g h t above t h e bed and i s o t o p i c c o m p o s i t i o n . West and K r o u s e (1972) o b s e r v e d an a l t i t u d e e f f e c t o f 0 . 4 ° / o o / 1 0 0 m f o r 5 0 1 8 o f s u r f a c e s a m p l e s on t h e E a s t s i d e of R u s t y G l a c i e r , a l t h o u g h on t h e West s i d e a r e v e r s a l o f t h e a l t i t u d e e f f e c t was a t t r i b u t e d t o s u p e r i m p o s e d i c e . From my o b s e r v a t i o n s , I c a n n o t c o n c l u d e t h a t an a l t i t u d e e f f e c t i s p r e s e n t i n b a s a l i c e , nor c a n I c o n f i r m s u c h an e f f e c t i n b u l k 48 F i g u r e 10. TR81 heavy i s o t o p e r e l a t i o n s h i p . The d a t a a r e a l i g n e d on a s l o p e of 5.79 ±0.40 w h i c h i s c h a r a c t e r i s t i c o f snow e v o l u t i o n p r o c e s s e s . The v a r i a t i o n s e v i d e n t i n F i g u r e 9 s u g g e s t d i f f e r e n t o r i g i n a l i s o t o p i c c o m p o s i t i o n s o r f r a c t i o n a t i o n p r o c e s s e s f o r t h e d i f f e r e n t s a m p l e s . The s l o p e may c h a r a c t e r i z e t h e s amples n o t a f r a c t i o n a t i o n p r o c e s s . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on e a c h p o i n t . TRAPRIDGE GLACIER 49 i c e . Snow e v o l u t i o n p r o c e s s e s p r o b a b l y mask a l t i t u d e i s o t o p i c v a r i a t i o n s i n T r a p r i d g e and Backe G l a c i e r . A t e a c h s i t e I c l a s s i f i e d t h e i c e i n t o t h e f o l l o w i n g c a t e g o r i e s : 1. C l e a r . I c e t h a t i s t r a n s l u c e n t w i t h a minimum of b u b b l e s . 2. B u b b l y I c e I . I c e t h a t c o n t a i n s b u b b l e s up t o a p p r o x i m a t e l y 10% o f t h e volume ( q u a l i t a t i v e j u d g e m e n t ) . 3. B u b b l y I c e I I . I c e t h a t i s opaque due t o t h e h i g h c o n c e n t r a t i o n o f b u b b l e s . 4. D e b r i s I . I c e t h a t c o n t a i n s d e b r i s c o n c e n t r a t i o n s under 10% by mass ( r e p r e s e n t a t i v e s amples were measured t o e s t a b l i s h t h i s c l a s s i f i c a t i o n ) . 5. D e b r i s I I . I c e t h a t c o n t a i n s d e b r i s c o n c e n t r a t i o n s o v e r 10% by mass. E a c h i c e t y p e was p r e s e n t i n a t l e a s t two of t h e b a s a l i c e c o r e s . C l e a r l a y e r s were f r e q u e n t l y f o u n d j u s t above d e b r i s l a y e r s and i n many s a m p l e s , i n c l u d i n g t h e b u l k c o r e f r o m TRST8, c l e a r i c e was i s o t o p i c a l l y h e a v i e r t h a n s u r r o u n d i n g i c e ( d i s c u s s e d below f o r e a c h c o r e ) . Hobbs (1974) o u t l i n e s t h e r e s u l t s o f f r e e z i n g e x p e r i m e n t s on b u l k i c e w h i c h i n d i c a t e t h a t b u b b l e s a r e s m a l l e r and d e n s e r f o r f a s t e r f r e e z i n g r a t e s . The o b s e r v a t i o n s i m p l y t h a t c l e a r i c e w i t h o n l y a few l a r g e b u b b l e s forms d u r i n g s l o w - f r e e z i n g (on t h e o r d e r of 1 0 - 6 m s ~ 1 ) I f f r e e z i n g a t t h e g l a c i e r bed i s a f f e c t e d i n a s i m i l a r way, c l e a r i c e would be i s o t o p i c a l l y h e a v i e s t f o l l o w e d by B u b b l y I c e I and t h e n B u b b l y 50 I c e I I . B u b b l y I c e I was n o t c o n s i s t e n t l y h e a v i e r t h a n B u b b l y I c e I I and i n some c a s e s c l e a r i c e was l i g h t e r t h a n t h e b o r d e r i n g b u b b l y l a y e r s . B u b b l e f o r m a t i o n d u r i n g b u l k f r e e z i n g a t t h e e x p e r i m e n t a l r a t e s c a n n o t e x p l a i n t h e o b s e r v e d i s o t o p i c v a r i a t i o n s w i t h b u b b l e c o n t e n t . D e b r i s s e q u e n c e s c o n s i s t e d o f d e b r i s l a y e r s o f 0-40 cm t h i c k n e s s s a n d w i c h e d between i c e l a y e r s of 0-70 cm t h i c k n e s s . The s e d i m e n t c o n c e n t r a t i o n s r a n g e d from 0% t o 50% and g r e a t e r i n t h e m easured l a y e r s . G r a i n s i z e a n a l y s e s o f d e b r i s l a y e r s and m o r a i n e samples showed smooth d i s t r i b u t i o n s , a l t h o u g h i n two s i z e r a n g e s , 1.00 and 3.50, t h e r e were s m a l l p e a k s i n c o n c e n t r a t i o n by mass ( S e c t i o n 3 . 4 ) . T h e s e r a n g e s may r e p r e s e n t c h a r a c t e r i s t i c s i z e s of t h e p r o c e s s e s o f e r o s i o n o f T r a p r i d g e and Backe b e d r o c k . C l a y f r a c t i o n s i n t h e d e b r i s l a y e r s a r e l o w e r t h a n i n t h e g r o u n d m o r a i n e s a m p l e s . T h i s s i t u a t i o n may a r i s e b e c a u s e o f r e j e c t i o n of f i n e m a t e r i a l s a t a f r e e z i n g f r o n t . The i s o t o p i c p r o f i l e s o f t h e b a s a l c o r e s r a n g e d from r e l a t i v e l y c o n s t a n t 5 v a l u e s between d e b r i s l a y e r s t o a d e p l e t i o n o r e n r i c h m e n t between l a y e r s . The most common s t r a t i g r a p h y s h i f t e d t o more n e g a t i v e 5 downwards a c r o s s a d e b r i s l a y e r , and as h e i g h t a b o v e t h e bed d e c r e a s e d f u r t h e r , t h e i c e became h e a v i e r u n t i l t h e n e x t d e b r i s l a y e r and a s h i f t t o l i g h t e r i c e . I f a r e s e r v o i r w i t h c o n s t a n t 6 v a l u e s i s assumed, t h e s t r a t i g r a p h i c r e s u l t s s h o u l d be o p p o s i t e t o t h e s e o b s e r v a t i o n s . B e f o r e e x a m i n i n g mechanisms t h a t c o u l d p r o d u c e t h e o b s e r v e d p r o f i l e s , I w i l l d i s c u s s t h e d e t a i l s o f r e s u l t s f r o m e a c h s i t e , and compare t h e b a s a l and b u l k i c e r e s u l t s . 51 3.2 S I T E RESULTS I have u s e d t h e S O 1 8 r e s u l t s t o i l l u s t r a t e t h e i s o t o p i c s t r a t i g r a p h y b e c a u s e t h e 6D p r o f i l e s p a r a l l e l t h e oxygen r e s u l t s and t h e h y d r o g e n a n a l y s e s were o n l y done f o r s e l e c t e d s a m p l e s ( a p p r o x i m a t e l y e v e r y t h i r d s a m p l e ) . I examine t h e heavy i s o t o p e r e l a t i o n s h i p f o r e a c h s i t e a l s o , t o show t h e s i t e v a r i a t i o n s . The r e s u l t s a r e combined a f t e r t h i s s e c t i o n t o c o n s i d e r d i f f e r e n c e s i n m e t e o r i c w a t e r , b u l k and b a s a l i c e . 3.2.1 TRST8 F i g u r e 11 shows t h e s t r a t i g r a p h y of t h e b u l k i c e c o r e from TRST8. T h e r e i s a v a r i a t i o n o f a p p r o x i m a t e l y 3 ° / 0 0 i n 8 0 1 8 o v e r t h e 1.00 m l e n g t h . One c l e a r i c e l a y e r i s h e a v i e r t h a n t h e r e s t o f t h e i c e . The heavy i s o t o p e r e l a t i o n s h i p ( F i g u r e 12) has a s l o p e o f 7.34 ±.43 and s c a t t e r o f t h e d a t a p o i n t s i s p r o b a b l y an i n d i c a t i o n o f t h e c o m p l e x i t y of snow e v o l u t i o n p r o c e s s e s . 3.2.2 TRB2 The TRB2 l a b o r a t o r y and f i e l d r e s u l t s ( F i g u r e 13) i l l u s t r a t e t h e 6 0 1 8 e n r i c h m e n t between d e b r i s l a y e r s w i t h d e c r e a s i n g h e i g h t above t h e b e d . The f i n e r l a b o r a t o r y s a m p l i n g ( d i s c o n n e c t e d l i n e s ) r e v e a l s t h e h e a v i e r c l e a r i c e l a y e r s . Two c l e a r l a y e r s a r e a l s o j u s t a bove d e b r i s l a y e r s . T h e r e i s no a p p a r e n t o v e r a l l s h i f t between u p p e r and l o w e r s a m p l e s t h a t would i n d i c a t e a v a r i a t i o n w i t h h e i g h t above t h e bed, but t h e c o r e i s o n l y 0.50 m i n l e n g t h . The s h i f t s o f f o u r s a m p l e s from t h e heavy i s o t o p e r e l a t i o n s h i p of t h e r e m a i n d e r o f t h e d a t a ( F i g u r e 14) i s 52 F i g u r e 11. TRST8 i s o t o p i c s t r a t i g r a p h y . TRST8 c o r e was f r o m s i t e 8 a t t h e t o p of t h e b u l g e . The i c e was l a y e r e d and had a d i p o f a p p r o x i m a t e l y 40° t o t h e g l a c i e r s u r f a c e . One of t h e c l e a r l a y e r s was t h e h e a v i e s t i c e i n t h e c o r e , but t h e r e were a l s o c l e a r l a y e r s t h a t were l i g h t e r t h a n b u b b l y i c e i n t h e r e s t o f t h e c o r e . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on t h e l o w e r r i g h t . TRAPRIDGE ST8 FIELD CO LU ^ DEBRIS I H DEBRIS I I • CLEAR 0 BUBBLY 1 BUBBLY I I -ERROR BARS 1 1 1 T -28 -27 -26 -25 -24 -23 8 0 1 8 (7..) 53 F i g u r e 12. TRST8 heavy i s o t o p e r e l a t i o n s h i p . The e q u a t i o n of t h e b e s t f i t l i n e t h r o u g h t h e d a t a i s 5D = 7.34 5 0 1 8 - 8 . 7 l ° / 0 0 . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on e a c h p o i n t . TRAPRIDGE GLRCIER 54 F i g u r e 13. TRB2 i s o t o p i c s t r a t i g r a p h y . TRB2 i s l o c a t e d on an i c e f a c e i n s t a g n a n t i c e below t h e b u l g e on T r a p r i d g e G l a c i e r . The c o r e was t a k e n from t h e base of t h e f a c e , b u t t h e i c e e x t e n d s below a s u r f a c e o f c o v e r i n g m a r g i n a l d e b r i s . The f i e l d and l a b o r a t o r y samples a r e p l o t t e d and a r e e q u a l w i t h i n e x p e r i m e n t a l e r r o r s . The l a b o r a t o r y samples a r e p l o t t e d as d i s c o n n e c t e d l i n e s . N e g a t i v e s h i f t s a c r o s s d e b r i s l a y e r s and i n c r e a s i n g 5 between l a y e r s a r e a p p a r e n t . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on t h e l o w e r r i g h t . TRAPRIDGE BASE 2 CO CO LU -z. CJ ^ D E B R I S I H D E B R I S I I • CLEAR [TO BUBBLY I 0 BUBBLY I I ERROR BARS -28 -26 -24 55 F i g u r e 14. TRB2 heavy i s o t o p e r e l a t i o n s h i p . The l e f t s h i f t of f o u r samples ( c i r c l e d p o i n t s ) i s u n e x p l a i n e d . T h r e e o f t h e s e s a m p l e s had v a r i a b l e r e p e a t 6D a n a l y s e s , a l t h o u g h r e p e a t 6 0 ' 8 v a l u e s d i d not change ( t h e a v e r a g e 6D has been p l o t t e d ) . The m a j o r i t y of samples a r e s i m i l a r t o o t h e r b a s a l i c e r e s u l t s and have a s l o p e o f 7.09 ±0.77 The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on e a c h p o i n t . & 0 1 8 c/..) & D ("/.) -2U0 TRAPRIDGE GLACIER 5 6 u n e x p l a i n e d . T h r e e o f t h e s a m p l e s had v a r i a t i o n s o f 4 ° / 0 o i n SD o v e r s e v e r a l r e p e a t a n a l y s e s . T h r o u g h o u t t h e i s o t o p i c work, t h e r e were no o t h e r s a m p l e s t h a t had t h i s d i s c r e p a n c y , even s a m p l e s t h a t were a n a l y z e d on t h e same r u n . The r e a s o n s f o r t h i s r e s u l t a r e n o t u n d e r s t o o d , p a r t i c u l a r l y s i n c e r e p e a t S O 1 8 a n a l y s e s d i d n o t v a r y . The m a j o r i t y of sam p l e s have a c h a r a c t e r i s t i c s l o p e o f 7.09 ± 0 . 7 7 . 3.2.3 TRC1 The TRC1 r e s u l t s ( F i g u r e 15) have a s m a l l e n r i c h m e n t between some o f t h e d e b r i s l a y e r s b u t t h e r e a r e o s c i l l a t i o n s i n t h e i s o t o p i c c o m p o s i t i o n . C l e a r l a y e r s a r e j u s t above many o f t h e d e b r i s l a y e r s , a l t h o u g h t h e S O 1 8 e n r i c h m e n t s a r e not as g r e a t a s t h e s h i f t s i n t h e TRB1 c o r e . T h e r e i s a l s o no s i g n i f i c a n t o v e r a l l i s o t o p i c s h i f t o v e r t h e 1.00 m c o r e . B e c a u s e o f t h e s m a l l r a n g e of 6 v a l u e s , TRC1 b a s a l i c e p l o t t e d i n a s m a l l r e g i o n on t h e 5 D / 5 0 1 8 g r a p h ( F i g u r e 1 6 ) . The s l o p e o f t h e hea v y i s o t o p e r e l a t i o n s h i p i s 6.88 ± 0 . 4 5 . 3.2.4 TRC2 The TRC2 s a m p l e s from b a s a l i c e w i t h no d e b r i s l a y e r s , have a 3 ° / 0 0 S O 1 8 s h i f t i n t h e l a b o r a t o r y s t r a t i g r a p h y ( F i g u r e 1 7 ) . I n t h e more c o a r s e l y sampled f i e l d s a m p l e s , I measured a s h i f t o f 1.5°/oo« The l a r g e change may i n d i c a t e : 1. A l a y e r o f s e g r e g a t e d i c e t h a t formed a f t e r t h e g l a c i e r had s u r g e d on t o t h e lo w e r b e d . 2. S h e a r i n g a t t h e bed w h i c h m i g h t be e x p e c t e d f o r a 57 F i g u r e 15. TRC1 i s o t o p i c s t r a t i g r a p h y . The TRC1 s i t e was i n a m e l t w a t e r t u n n e l t h a t c u t t h r o u g h t h e b a s a l d e b r i s l a y e r s ( F i g u r e 1 ) . C l e a r l a y e r s a r e o f t e n l o c a t e d j u s t above d e b r i s l a y e r s . T h e r e a r e n e g a t i v e s h i f t s a c r o s s d e b r i s l a y e r s e x c e p t a t t h e l a y e r a t 40 cm. A d i s p e r s e d d e b r i s l a y e r ( a t 80 cm), s h i f t s t o l i g h t e r i s o t o p i c c o m p o s i t i o n o v e r 9 cm of i c e . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on t h e lower r i g h t . TRAPRIDGE CAVE 1 F I E L D c o CO LU L J §3 D E B R I S I H D E B R I S I I • CLEAR [3 BUBBLY I £3 BUBBLY I I ERROR BARS & 0 1 8 r/..) 58 F i g u r e 16. TRC1 heavy i s o t o p e r e l a t i o n s h i p . The samples from TRC1 have a s m a l l v a r i a t i o n w i t h a s l o p e o f 6.88 ± 0 . 4 5 . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on e a c h p o i n t . & 0 1 0 a.) TRAPRIDGE GLACIER 59 F i g u r e 17. TRC2 i s o t o p i c s t r a t i g r a p h y . The TRC2 s i t e was i n a t u n n e l t h r o u g h c e n t r a l T r a p r i d g e i c e below t h e b u l g e . The i c e was f r o z e n t o t h e bed and some b a s a l d e b r i s had been f r o z e n i n t o t h e i c e a t t h e bed. F i e l d and l a b o r a t o r y samples ( d i s c o n n e c t e d l i n e s ) a r e p l o t t e d and a g r e e w i t h i n e x p e r i m e n t a l e r r o r e x c e p t a c r o s s t h e s h i f t i n 5 0 1 8 . T h i s d i s c r e p a n c y i s p r o b a b l y a r e s u l t o f f i e l d s a m p l i n g a t a d i f f e r e n t a n g l e t o t h e l a b o r a t o r y work. T h e r e was no l a y e r i n g i n t h e d e n s e l y b u b b l e d i c e . The l a r g e n e g a t i v e s h i f t may i n d i c a t e s h e a r i n g or i n c o r p o r a t i o n of s e g r e g a t e d i c e ( s e e t e x t ) . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on t h e lo w e r r i g h t . TRAPRIDGE CAVE 2 - 3 0 - 2 9 - 2 8 - 2 7 - 2 6 - 2 5 60 F i g u r e 18. TRC2 heavy i s o t o p e r e l a t i o n s h i p . The c i r c l e d p o i n t s a r e from t h e upper p a r t of t h e c o r e , above an i s o t o p i c s h i f t ( F i g u r e 17 and t e x t ) . The s l o p e of t h e b e s t f i t l i n e f o r a l l o f t h e d a t a p o i n t s i s 7.07 ±0.34 w h i c h i s i n t e r m e d i a t e t o b a s a l and b u l k i c e s l o p e s . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on e a c h p o i n t . TRAPRIDGE GLACIER 61 r a p i d l y d e c e l e r a t i n g s u r g e (a s h e a r t h r o u g h t h e l a y e r s c o u l d c a u s e an i s o t o p i c d i s c o n t i n u i t y ) . The i c e was v e r y b u b b l y ( s p h e r i c a l b u b b l e s l e s s t h a n 1 mm i n d i a m e t e r ) a n d t h e r e was no i c e l a y e r i n g . The s h i f t may i n d i c a t e a change i n i s o t o p i c c o m p o s i t i o n of t h e i n p u t w a t e r . The heavy i s o t o p e g r a p h ( F i g u r e 18) does not i n d i c a t e d i f f e r e n t i c e t y p e s from above and below t h e s h i f t ( p o s s i b l y b e c a u s e o f t h e s m a l l sample s i z e ) . The s l o p e o f t h e c o m p l e t e d a t a s e t i s 7.07 ±0.34 w h i c h i s i n t e r m e d i a t e t o t h e b u l k and b a s a l i c e s l o p e s ( F i g u r e 23) . 3.2.5 BA1 BA1 s a m p l e s from t h e d e b r i s - l a d e n Backe i c e f a c e have a g r e a t e r v a r i a t i o n i n i s o t o p i c c o m p o s i t i o n t h a n T r a p r i d g e i c e , but e n r i c h m e n t between l a y e r s and and i s o t o p i c s h i f t s a c r o s s d e b r i s l a y e r s a r e s t i l l e v i d e n t ( F i g u r e 1 9 ) . The l a r g e s t s h i f t o c c u r s i n 8 cm o f t h e u p p e r c o r e (197-205 cm) where S O 1 8 f i r s t d e c r e a s e s by o v e r 3 ° / 0 o t h e n i n c r e a s e s a l m o s t 5 ° / 0 o t o a c l e a r l a y e r . The l a r g e p o s i t i v e s h i f t i s i n a s e c t i o n o f c l e a r i c e . The BA1 heavy i s o t o p e r e l a t i o n s h i p has a s l o p e o f 6.27 ± 0 . 1 7 . T h i s s e t of s a m p l e s r e p r e s e n t s Backe b a s a l i c e and t h e p l o t i s p r e s e n t e d i n S e c t i o n 3.3.3 ( F i g u r e 2 4 ) . 3.2.6 BA2 The BA2 s t r a t i g r a p h y has 5 s h i f t s a c r o s s t h e d e b r i s l a y e r s but e n r i c h m e n t between l a y e r s i s n o t as c o n s i s t e n t as i n o t h e r c o r e s ( F i g u r e 2 0 ) . One i n t e r e s t i n g f e a t u r e i s t h e h e a v i e r c l e a r 62 F i g u r e 19. BA1 i s o t o p i c s t r a t i g r a p h y . The BA1 c o r e was from t h e t e r m i n a l v e r t i c a l f a c e . The Backe G l a c i e r had a w i d e r range o f i s o t o p i c c o m p o s i t i o n t h a n T r a p r i d g e G l a c i e r . Two i n t e r e s t i n g f e a t u r e s o f t h e i s o t o p i c s t r a t i g r a p h y a r e t h e l a r g e n e g a t i v e t o p o s i t i v e s h i f t n e a r t h e t o p o f t h e c o r e (197-205 cm) and s h i f t s a c r o s s t h e d e b r i s l a y e r s . The f i e l d and l a b o r a t o r y ( d i s c o n n e c t e d l i n e s ) r e s u l t s a g r e e e x c e p t i n a 10 cm l e n g t h ( a t 160 cm). T h i s d i s c r e p a n c y i s p r o b a b l y a r e s u l t of f i e l d s a m p l i n g a c r o s s t h e l a y e r s . T h e r e i s an i n c r e a s e i n 6 0 1 8 between some of t h e d e b r i s l a y e r s b u t t h e r e i s a l s o a d e c r e a s e between some l a y e r s . The BA1 heavy i s o t o p e g r a p h i s t h e Backe b a s a l l i n e i n F i g u r e 24. The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on t h e l o w e r r i g h t . 63 BACKE ICE FACE 1 CO CO LU ~ZL CJ 160-- 220 200 - 180 •- 160 - mo - 120 - 100 DEBRIS I H§ DEBRIS I I • CLEAR 0 BUBBLY I BUBBLY I I — ERROR BARS &Q 1 8 ('/.) 64 i c e l a y e r t h a t i s s a n d w i c h e d between two z o n e s o f d i s p e r s e d d e b r i s - l a d e n i c e . The BA2 s a m p l e s have n o t been a n a l y z e d f o r d e u t e r i u m c o n c e n t r a t i o n s so I have n o t d e t e r m i n e d a heavy i s o t o p e r e l a t i o n s h i p . 3.3 HEAVY ISOTOPE RELATIONSHIP 3.3.1 METEORIC RESULTS The m e t e o r i c s l o p e f o r T r a p r i d g e and Backe G l a c i e r s i s e s t a b l i s h e d f r o m f i v e s amples o f f r e s h snow and m e l t w a t e r ( F i g u r e 2 1 ) . The r e l a t i o n s h i p from l e a s t s q u a r e s c u b i c c a l c u l a t i o n s i s 5D = 8.04 ±0.34 50 1 8 + 12.63 ±9.00 %><>. The s l o p e of 8.04 i s s i m i l a r t o r e s u l t s from W h i t e h o r s e , 7.95 ±0.2 2 (many s a m p l e s ) , and West and K r o u s e ( 1 9 7 2 ) , 8.2 ( s i x s a m p l e s ) ( S e c t i o n 1.3.2). West and K r o u s e i n c l u d e d one sample o f r a i n and one sample of snow from R u s t y G l a c i e r . The i n t e r c e p t o f 12.63°/oo i s a l m o s t d o u b l e t h o s e o f t h e o t h e r two s t u d i e s however, summer p r e c i p i t a t i o n c a n have a r e l a t i v e i n c r e a s e i n 6 0 1 8 w h i c h c o u l d c a u s e t h e o b s e r v e d s h i f t . In a d d i t i o n , t h e r e i s a l a r g e u n c e r t a i n t y due t o t h e s m a l l sample s i z e w h i c h c o u l d a c c o u n t f o r t h e d i f f e r e n c e . The m e t e o r i c 5 v a l u e s c o v e r t h e r a n g e o f i s o t o p i c c o m p o s i t i o n s w h i c h I have measured on T r a p r i d g e and Backe G l a c i e r s . 6 5 F i g u r e 20. BA2 i s o t o p i c s t r a t i g r a p h y . The f i e l d and l a b o r a t o r y ( d i s c o n n e c t e d l i n e s ) r e s u l t s f r o m BA2 a g r e e w i t h i n e x p e r i m e n t a l e r r o r e x c e p t o v e r a 10 cm l e n g t h . T h i s d i s c r e p a n c y c o u l d be c o n t a m i n a t i o n or s a m p l i n g a t d i f f e r e n t a n g l e s i n t h e two c o r e s . S h i f t s a c r o s s d e b r i s l a y e r s a r e p a r t i c u l a r l y a p p a r e n t i n t h e l a b o r a t o r y r e s u l t s . I was a b l e t o i s o l a t e and a n a l y z e one c l e a r i c e sample a t 12 cm which had a p o s i t i v e s h i f t from t h e two a d j a c e n t l a y e r s o f d e b r i s . B e c a u s e I d i d not a n a l y z e BA2 s a m p l e s f o r d e u t e r i u m , t h e r e i s no heavy i s o t o p e g r a p h . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s on t h e l o w e r r i g h t . BACKE ICE FACE 2 C_> CO CO LU C_) D E B R I S I Hi D E B R I S I I • CLEAR [TO BUBBLY I 0 BUBBLY I I ERROR BARS -28 -27 -26 -25 66 F i g u r e 21. T r a p r i d g e G l a c i e r b u l k heavy i s o t o p e r e l a t i o n s h i p . B u l k i c e samples a r e s h i f t e d t o t h e r i g h t of t h e m e t e o r i c w a t e r s . Snow e v o l u t i o n p r o c e s s e s c an c a u s e t h i s s h i f t b e c a u s e of t h e c o n c e n t r a t i o n of heavy i s o t o p e s i n t h e snow. The s l o p e s of t h e b e s t f i t l i n e s a r e l i s t e d on t h e a p p r o p r i a t e l i n e s . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s i n t h e upper l e f t c o r n e r . &Ql8 (7..) - 2 8 - 2 3 O M E T E O R I C A BULK - 1 8 0 - 1 9 0 "200 & Q { ' / . . ) - - 2 1 0 - 2 2 0 TRAPRIDGE GLACIER 67 3.3.2 BULK ICE B u l k i c e r e s u l t s f o r T r a p r i d g e a r e t a k e n from TRST8 (20 s a m p l e s ) and TR81 (5 s a m p l e s ) . The TR81 samp l e s were from t h e r i g h t i c e f a c e and were n o t a f f e c t e d by r e c e n t s u p e r p o s i t i o n p r o c e s s e s t h a t were s u s p e c t e d t o have a l t e r r e d t h e 1981 s u r f a c e s a m p l e s . A l l o f t h e d a t a p o i n t s p l o t t o t h e r i g h t o f t h e m e t e o r i c l i n e ( F i g u r e 2 1 ) . F r a c t i o n a t i o n by snow e v o l u t i o n p r o c e s s e s c a n c o n c e n t r a t e heavy i s o t o p e s i n t h e snow, and c a u s e a s h i f t t o t h e r i g h t of t h e m e t e o r i c l i n e on a heavy i s o t o p e p l o t . The l i n e f i t t o t h e d a t a i s 8D = 7.53 ±0.39 S O 1 8 - 3.93 ±10.29 % o . The TRST8 s a m p l e s a r e s c a t t e r e d a b o u t t h e b e s t f i t l i n e . I t i s i m p o r t a n t t o r e c o g n i z e t h a t t h e o r i g i n a l p r e c i p i t a t i o n t h a t f o r m e d t h e d i f f e r e n t l a y e r s d i d n o t n e c e s s a r i l y have a common i s o t o p i c c o m p o s i t i o n , n o r d i d t h e snow and water e v o l v e a l o n g s i m i l a r i s o t o p i c p a t h s . I f t h e samples had e v o l v e d from a common i s o t o p i c r e s e r v o i r , t h e d a t a p o i n t s w i l l r e p r e s e n t v a r i o u s s t a g e s o f a f r a c t i o n a t i o n p r o c e s s . I t i s more p r o b a b l e t h a t snow e v o l u t i o n p r o c e s s e s s h i f t e d t h e d i f f e r e n t snow l a y e r s a l o n g i s o t o p i c p a t h s w i t h s l o p e s l e s s t h a n 7.53, and t h e 7.53 s l o p e c h a r a c t e r i z e s t h e s a m p l e s , not a f r a c t i o n a t i o n p r o c e s s . T h i r t e e n i c e and o l d snow samples were a n a l y z e d t o e s t a b l i s h t h e heavy i s o t o p e r e l a t i o n s h i p f o r Backe b u l k i c e ( F i g u r e 2 2 ) , ' 1One r e l a t i v e l y d e p l e t e d sample was i n c l u d e d i n t h e s l o p e a n a l y s e s but i s n o t p l o t t e d on t h e g r a p h i n F i g u r e 22. 6 8 5D = 7.31 ± 0 . 1 3 6 0 1 8 - 10.42 ±3.30 %><>. A l t h o u g h t h e Backe s a m p l e s r e p r e s e n t a l a r g e r g e o g r a p h i c a l s p r e a d , t h e y have l e s s s c a t t e r t h a n t h e T r a p r i d g e s a m p l e s . They a r e a l s o s h i f t e d t o t h e r i g h t o f t h e m e t e o r i c l i n e . A c o m p a r i s o n w i t h t h e 1981 s u r f a c e s a m p l e s a s s i s t s i n i d e n t i f y i n g t h e p r o c e s s e s t h a t l e a d t o t h e b u l k i c e s h i f t s . T h r e e of t h e 1981 samples p l o t t o t h e l e f t of t h e m e t e o r i c l i n e . S u b l i m a t i o n and e v a p o r a t i o n w i l l n o t n o r m a l l y c a u s e s h i f t s i n t h a t d i r e c t i o n . C o n d e n s a t i o n p r o c e s s e s c a n , b u t i t i s more p r o b a b l e t h a t snow p e r c o l a t i o n mechanisms p r o d u c e i c e t h a t i s s h i f t e d t o t h e l e f t . Water p e r c o l a t i n g t h r o u g h snow and c o n t i n u o u s l y e x c h a n g i n g i s o t o p e s w i t h t h e c r y s t a l s , becomes d e p l e t e d i n heavy i s o t o p e s . J o u z e l and Souchez (1982) s u g g e s t t h a t i c e w h i c h p l o t s t o t h e l e f t of b u l k i c e r e p r e s e n t s l a t e r f r a c t i o n s o f a f r e e z i n g e x c h a n g e p r o c e s s . The 1981 s a m p l e s w i t h t h e r e p r e s e n t a t i v e s l o p e o f 5.79 ( S e c t i o n 3.2.2) may be s u p e r i m p o s e d i c e t h a t has fo r m e d from water d e p l e t e d by p e r c o l a t i o n t h r o u g h snow. O t h e r b u l k i c e sam p l e s from b o t h g l a c i e r s have e v o l v e d from e n r i c h e d snow l a y e r s t h a t p l o t t o t h e r i g h t o f t h e m e t e o r i c l i n e . T h e s e snow e v o l u t i o n p r o c e s s e s a l t e r t h e m e t e o r i c p r o p e r t i e s of t h e o r i g i n a l snow and c o m p l i c a t e t h e i d e n t i f i c a t i o n o f b a s a l i c e , b e c a u s e t h e s l o p e s a r e a l s o r e d u c e d f r o m t h e m e t e o r i c v a l u e s . 6 9 Figure 22. Backe G l a c i e r b u l k heavy i s o t o p e r e l a t i o n s h i p . The b u l k i c e samples a r e s h i f t e d t o t h e r i g h t of t h e m e t e o r i c l i n e s i m i l a r l y t o T r a p r i d g e b u l k samples ( F i g u r e 2 1 ) . The s l o p e s o f t h e b e s t f i t l i n e s a r e r e c o r d e d on t h e a p p r o p r i a t e l i n e s . One p o i n t ( - 3 3 . 1 3 ° / 0 0 , - 2 5 4 . 3 0 ° / o o ) i s not p l o t t e d . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s i n t h e upper l e f t c o r n e r . -28 -27 -22 - -190 O M E T E O R I C A BULK -170 -180 8D {'/..) -200 - -210 •220 BflCKE GLACIER 70 3.3.3 BASAL ICE T r a p r i d g e b a s a l s a m p l e s came from two s i t e s , TRB2 and TRC1 (30 s a m p l e s ) . The heavy i s o t o p e r e l a t i o n s h i p i s p l o t t e d i n F i g u r e 23 and t h e b e s t f i t l i n e i s 6D = 6.75 ±0.28 6 0 1 8 - 23.96 ±7.1 7 ° / 0 0 . A l t h o u g h t h e b a s a l 5 v a l u e s a r e a l l w i t h i n t h e l i m i t s of b u l k v a l u e s , t h e a v e r a g e 5 0 1 8 of b a s a l samples i s s h i f t e d a p p r o x i m a t e l y 1 ° / o o h e a v i e r t h a n t h e a v e r a g e of b u l k i c e s a m p l e s . T h i s o b s e r v a t i o n may s i m p l y be a r e s u l t o f t h e s a m p l i n g p r o c e d u r e . The b a s a l d a t a p o i n t s a p p e a r t o t r e n d a c r o s s t h e b u l k i c e l i n e , b ut t h e t e n d e n c y i s n o t p r o n o u n c e d . The b a s a l s l o p e i s a p p r o x i m a t e l y 0.8 l e s s t h a n t h e b u l k s l o p e w h i c h i s g r e a t e r t h a n t h e c o m b i n e d u n c e r t a i n t i e s a t t h e 1a l e v e l . A l l o f t h e b a s a l s amples a r e t o t h e r i g h t o f t h e m e t e o r i c l i n e as f o r b u l k i c e , but t h e s c a t t e r i s l e s s t h a n t h e b u l k s a m p l e s . Backe b a s a l d a t a ( F i g u r e 24) i s f r o m BA1 (34 s a m p l e s ) . The l e a s t s q u a r e s c u b i c f i t i s 8D = 6.27 ±0.17 S O 1 8 - 34.42 ±4. 3 2 % 0 . The a v e r a g e o f Backe b a s a l r e s u l t s i s a l s o s h i f t e d a p p r o x i m a t e l y 1 ° / o o f o r 5 0 1 8 compared t o t h e b u l k a v e r a g e and most b a s a l s amples a r e s h i f t e d l e f t o f t h e b u l k s a m p l e s ; t h r e e s a m p l e s a r e a l s o l e f t o f t h e m e t e o r i c s a m p l e s . The t r e n d o f Backe b a s a l i c e i s e a s i e r t o d i s t i n g u i s h f r o m b u l k i c e t h a n f o r T r a p r i d g e d a t a . 71 F i g u r e 23. T r a p r i d g e G l a c i e r b a s a l h e a v y i s o t o p e r e l a t i o n s h i p . The b a s a l i c e samples have been p l o t t e d w i t h t h e m e t e o r i c and b u l k i c e r e s u l t s . The b a s a l s a m p l e s a r e n o t o b v i o u s l y d i s t i n g u i s h a b l e from t h e b u l k i c e r e s u l t s a l t h o u g h t h e s l o p e i s d i f f e r e n t . Because of i s o t o p i c p r o c e s s e s i n c l u d i n g m i x i n g and n o n - e q u i l i b r i u m t h e s l o p e s may n o t r e p r e s e n t f r a c t i o n a t i o n p r o c e s s e s ( s e e t e x t ) . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s i n the upper l e f t c o r n e r . - 2 8 - 2 7 - 2 6 - 2 5 -24 - 2 3 + B A S A L L_ - 2 2 0 TRAPRIDGE GLACIER 72 F i g u r e 24. Backe G l a c i e r b a s a l heavy i s o t o p e r e l a t i o n s h i p . The b a s a l i c e of Backe G l a c i e r had a w i d e r v a r i a t i o n i n 6 t h a n T r a p r i d g e s a m p l e s . The l i g h t e r i c e i s s h i f t e d t o t h e l e f t of t h e b u l k samples and i n t h r e e c a s e s , t o t h e l e f t of t h e m e t e o r i c l i n e . B a s a l i c e may f r e e z e from a r e s e r v o i r t h a t i s formed from s u r f a c e water and b a s a l m e l t . The samples t h a t a r e s h i f t e d t o t h e l e f t of t h e m e t e o r i c l i n e c o u l d r e p r e s e n t s u r f a c e m e l t t h a t has been d e p l e t e d by p e r c o l a t i o n t h r o u g h i c e and snow . l a y e r s . The u n c e r t a i n t i e s a r e i n d i c a t e d by t h e e r r o r b a r s i n t h e upper l e f t c o r n e r . -28 - 2 7 -26 -25 -24 -23 -22 -220 BACKE GLACIER 73 The c a l c u l a t e d s l o p e i s a p p r o x i m a t e l y 1 . 0 . l e s s t h a n t h e b u l k s l o p e and t h i s d i f f e r e n c e i s g r e a t e r t h a n t h e combined u n c e r t a i n t i e s even a t t h e 3a l e v e l . 3.4 WATER QUALITY AND SEDIMENT ANALYSES The s e d i m e n t a n a l y s e s were done by s t a n d a r d t e c h n i q u e s of s i e v i n g , h y d r o m e t e r a n a l y s i s and m i c r o p a r t i c l e c o u n t i n g ( C o u l t e r C o u n t e r ) . Sediment c o n c e n t r a t i o n i n d e b r i s l a y e r s was measured by wet and d r y s i e v i n g . M i c r o p a r t i c l e c o n c e n t r a t i o n s i n samples o f b u l k and b a s a l i c e ( f r o m between l a y e r s of d e b r i s ) were measured u s i n g a C o u l t e r C o u n t e r i n t h e UBC Department o f O c e a n o g r a p h y . Table 2. Sediment c o n c e n t r a t i o n s i n d e b r i s l a y e r s . Sample S158 S167 S189 S194 S195 S204 Mass R a t i o 19.7% 25.0% 53.3% 9.8% 32.5% 35.9% Sed i m e n t c o n c e n t r a t i o n s (by mass) i n d e b r i s l a y e r s v a r i e d f r o m a p p r o x i m a t e l y 0-50% and g r e a t e r ( T a b l e 2 ) . T y p i c a l s e d i m e n t d i s t r i b u t i o n s a r e i l l u s t r a t e d i n F i g u r e 25. Se d i m e n t f i n e r t h a n 3.5</> ( n e a r t o t h e s i l t / s a n d b o u n d a r y ) i s r e p r e s e n t e d a s a s i n g l e c a t e g o r y , and s e d i m e n t l a r g e r t h a n -2<t> ( g r a n u l e / s a n d b o u n d a r y ) i s r e p r e s e n t e d a s a s i n g l e c a t e g o r y . The c o n c e n t r a t i o n of c l a y and s i l t s i z e p a r t i c l e s v a r i e d f r o m 5.2%-94.4% o f t h e t o t a l s e d i m e n t mass. M i c r o p a r t i c l e c o u n t s i n t h e r a n g e from 0-25.6 nm were done u s i n g a c a l i b r a t e d C o u l t e r C o u n t e r w i t h a 77 urn a p e r t u r e . At l e a s t two r e a d i n g s o f e a c h sample were a v e r a g e d and b a c k g r o u n d 74 F i g u r e 25. T y p i c a l g r a i n s i z e d i s t r i b u t i o n i n d e b r i s l a y e r s . The two extreme s i z e r a n g e s r e p r e s e n t w i d e r <f> r a n g e s t h a n t h e r e s t o f t h e p o i n t s . GRAIN SIZE ( m m ) 0.4 -©-0.3 H 0.2 H o.i H 0.0 4.00 1.00 0.40 T 0.10 0.04 CX T T J L •4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 1.0 - 0.9 - 0.8 - 0.7 - 0.6 - 0.5 - 0.4 - 0.3 - 0.2 - 0.1 0.0 GRAIN SIZE <t> 75 F i g u r e 26. M i c r o p a r t i c l e c o n c e n t r a t i o n s i n b u l k and b a s a l i c e . The b u l k i c e p o i n t s r e p r e s e n t t h e a v e r a g e f o r 5 s a m p l e s from TRST8 and t h e b a s a l i c e p o i n t s r e p r e s e n t t h e a v e r a g e f o r 5 samples f r o m TRC1. S c a t t e r a r o u n d t h e mean was a maximum o f 20%. GRAIN SIZE (fjcm) 76 c o u n t s o f t h e 3% N a C l e l e c t r o l y t e s o l u t i o n were done a t t h e b e g i n n i n g and e n d i n g of a s e r i e s o f r u n s . B u l k i c e from TRST8 and b a s a l i c e f r o m i c e l a y e r s a t TRC1 were a n a l y z e d . C o u l t e r C o u n t e r a n a l y s e s g i v e t h e number o f p a r t i c l e s i n d i f f e r e n t s i z e r a n g e s d e s i g n a t e d by r a d i u s o f t h e p a r t i c l e s . An a p p r o x i m a t e t o t a l volume o f p a r t i c l e s can be c a l c u l a t e d u s i n g t h e a v e r a g e volume f o r e a c h s i z e r a n g e and t h e number of p a r t i c l e s . The a v e r a g e r a t i o o f t h e t o t a l volume of p a r t i c l e s t o t h e volume of sample ( w a t e r and s e d i m e n t ) f o r b u l k i c e i s 0.76 ppm compared t o 3.18 ppm f o r b a s a l i c e . F i g u r e 26 shows t y p i c a l d i s t r i b u t i o n s f o r b u l k and b a s a l i c e s a m p l e s . The b a s a l i c e has a g r e a t e r c o n c e n t r a t i o n w h i c h s u g g e s t s t h a t i c e between t h e d e b r i s l a y e r s i s d i f f e r e n t f r o m t h e b u l k i c e . The w a t e r q u a l i t y a n a l y s e s were done on a P e r k i n E l m e r a t o m i c a b s o r p t i o n s p e c t r o p h o t o m e t e r ( c a t i o n s ) and a D i o n e x M o d e l 21101 Ion C h r o m a t o g r a p h ( i o n s ) i n t h e F o r e s t F i r e S c i e n c e L a b o r a t o r y o f t h e 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 . Samples of b a s a l i c e f r o m l a y e r s between d e b r i s a t TRC1, and b u l k i c e s a m p l e s from TRST8 were a n a l y z e d f o r major c a t i o n and a n i o n c o n c e n t r a t i o n s . The r e s u l t s i n T a b l e 3 show t h a t b a s a l i c e had s i g n i f i c a n t l y g r e a t e r c o n c e n t r a t i o n s o f K +, Mg + + , C a + + and C l ~ . B e c a u s e t h e s a m p l e s were n o t f i l t e r e d i m m e d i a t e l y upon m e l t i n g , t h e r e s u l t s may be a f f e c t e d by a d s o r p t i o n o f i o n s o n t o s e d i m e n t p a r t i c l e s . 1 B e c a u s e b a s a l i c e has h i g h e r s e d i m e n t c o n c e n t r a t i o n s , a g r e a t e r p e r c e n t a g e of t h e i o n s c o u l d be removed by a d s o r p t i o n t o p a r t i c l e s t h a n i n t h e b u l k i c e . The d i f f e r e n c e i n i o n 1 Samples were m e l t e d f o r p e r i o d s of d a y s d u r i n g i s o t o p i c and w a ter q u a l i t y a n a l y s e s . 77 c o n c e n t r a t i o n between b a s a l and b u l k i c e w o u l d be g r e a t e r t h u s , t h e r e s u l t s s t i l l show t h a t T r a p r i d g e b a s a l i c e has i n c o r p o r a t e d more i m p u r i t i e s t h a n b u l k i c e . I t i s p o s s i b l e t h a t t h e b a s a l i c e o r i g i n a t e d a s b u l k i c e and some i n f l u e n c e , s u c h as h i g h e r a t m o s p h e r i c i m p u r i t y c o n c e n t r a t i o n s i n t h e p a s t o r c o n c e n t r a t i o n of i m p u r i t i e s n e a r t h e bed has c a u s e d t h e c o n t r a s t w i t h b u l k i c e , bu t t h i s e x p l a n a t i o n i s u n l i k e l y . The b a s a l i c e has p r o b a b l y i n c o r p o r a t e d i m p u r i t i e s d u r i n g b a s a l f r e e z i n g f r o m water c i r c u l a t i n g i n t h e s u b s t r a t e . Table 3. M a j o r i o n c o n c e n t r a t i o n s i n T r a p r i d g e i c e . A l l c o n c e n t r a t i o n s a r e i n j u e q ( u i v a l e n t s ) . The b u l k i c e sa m p l e s a r e S099-S115 and t h e b a s a l i c e sa m p l e s a r e S190-S195. Sample K + Na + Mg + + C a + + c i - N03" S04~ -S099 29.7 50.5 69.9 230.0 44. 6 113.2 171.6 S1 00 32.0 41.8 16.4 226.0 37. 5 11.8 180.3 SI 08 10.0 0.0 9.0 227.5 22. 0 16.0 27.5 SI 1 3 22.0 17.4 0.8 164.2 31 . 3 20.5 34.4 SI 1 5 10.7 0.0 0.0 136.7 32. 4 71.3 67.5 S190 77.5 75.7 201 .5 950. 1 87. 7 28.7 30.4 SI 91 52.4 13.0 97.0 881 .2 663. 2 26. 1 19.4 S1 92 29.7 3.9 85.5 970. 1 298. 4 26.3 16.9 S193 21.5 34.4 131.6 854.3 42. 0 103.4 331 .9 S1 94 35.3 1 02.2 188.3 665.7 57. 8 102.6 112.2 S1 95 28.9 92.2 974.5 1034.4 43. 7 1 05.0 93.5 The T r a p r i d g e b a s a l i c e has h i g h e r i o n c o n c e n t r a t i o n s t h a n A l p i n e g l a c i e r i c e r e p o r t e d i n H a l l e t e t a l . ( 1 9 7 8 ) , but s i m i l a r c o n c e n t r a t i o n s t o water and i c e samples a s s o c i a t e d w i t h a mud l a y e r a d h e r e d t o t h e bo t t o m o f a n o t h e r A l p i n e g l a c i e r r e p o r t e d i n Souchez and L o r r a i n ( 1 9 7 5 ) . The w a t e r q u a l i t y and s e d i m e n t r e s u l t s s u g g e s t t h a t b a s a l i c e c h a r a c t e r i s t i c s a r e d i f f e r e n t from b u l k i c e . A p r o c e s s o f b a s a l a c c r e t i o n i s t h e most p r o b a b l e e x p l a n a t i o n f o r t h e h i g h e r s e d i m e n t and i o n c o n c e n t r a t i o n s i n b a s a l i c e . C h a p t e r 4 DISCUSSION 4.1 INTERPRETATION OF RESULTS A model of t h e p r o c e s s e s o f b a s a l i c e and d e b r i s i n c o r p o r a t i o n a t t h e T r a p r i d g e and Backe beds must a c c o u n t f o r t h e i s o t o p i c r e s u l t s , p a r t i c u l a r l y , 1. I s o t o p i c S t r a t i g r a p h y (a) F r e q u e n t heavy c l e a r i c e and d e b r i s l a y e r s . (b) V a r i a b l e i s o t o p i c c o m p o s i t i o n s i n d e b r i s - l a d e n i c e w i t h f r e q u e n t e n r i c h m e n t from one d e b r i s l a y e r down t o t h e n e x t d e b r i s l a y e r . 2. S h i f t s i n t h e heavy i s o t o p e r e l a t i o n s h i p s o f Backe and T r a p r i d g e i c e . In a d d i t i o n t h e i c e , d e b r i s and water q u a l i t y c h a r a c t e r i s t i c s must be a c c o u n t e d f o r by p o t e n t i a l a c c r e t i o n mechanisms. I w i l l h i g h l i g h t t h e i s o t o p i c c h a r a c t e r i s t i c s o f Backe and T r a p r i d g e G l a c i e r s by a p p l y i n g t h e b a s a l f r e e z i n g models o f J o u z e l and Souchez (1982) and Souchez and J o u z e l (1984) ( s u b s e q u e n t l y r e f e r r e d t o a s t h e J o u z e l and Souchez m o d e l s ) . J o u z e l a n d Souchez (1982) assume t h a t b a s a l i c e f r e e z e s from a r e s e r v o i r w i t h i n i t i a l 5 v a l u e s t h a t c an be d e t e r m i n e d f rom t h e i n t e r s e c t i o n o f b a s a l and b u l k r e l a t i o n s h i p s on a 5 D / 5 0 1 8 g r a p h . N e w l y - f o r m e d i c e w i l l become p r o g r e s s i v e l y d e p l e t e d i n a c l o s e d s y s t e m , whereas an open s y s t e m w i t h a c o n s t a n t i s o t o p i c water i n p u t w i l l l e a d t o i s o t o p i c a l l y c o n s t a n t i c e . I f b a s a l i c e i s a c c r e t e d a l o n g a l o n g i t u d i n a l p r o f i l e a s B o u l t o n (1983) 78 79 t h e o r i z e s , a n d t h e f r e e z i n g w a t e r f l u x i s o f t h e same o r d e r a s t h e b a s a l w a t e r f l u x , t h e n i c e i s i n c r e a s i n g l y d e p l e t e d a s t h e d i s t a n c e f r o m t h e s o u r c e i n c r e a s e s . I f t h e f r a c t i o n o f water f r o z e n i s s m a l l compared t o t h e r e s e r v o i r s i z e ( f r e e z i n g f l u x much l e s s t h a n b a s a l w a t e r f l u x ) , t h e n t h e r e w i l l be n e g l i g i b l e i s o t o p i c v a r i a t i o n s . I f l o n g i t u d i n a l i c e v e l o c i t y i s s i g n i f i c a n t , h i g h e r i c e l a y e r s s h o u l d be e n r i c h e d compared t o l o w e r l a y e r s w h i c h a r e i n c o r p o r a t e d f u r t h e r d o w n - g l a c i e r f r o m d e p l e t e d b a s a l w a t e r . The i s o t o p i c s t r a t i g r a p h y r e s u l t s a r e c o n t r a r y t o t h e p r e d i c t i o n s a b o v e . In a v e r t i c a l s e q u e n c e , t h e 5 v a l u e s a r e n o t c o n s t a n t , and between two d e b r i s l a y e r s , h e a v y i s o t o p e c o n c e n t r a t i o n s o f t e n i n c r e a s e w i t h d e c r e a s i n g h e i g h t above t h e bed, between two d e b r i s l a y e r s . T h e r e was no s i g n i f i c a n t change i n i s o t o p i c c o m p o s i t i o n f r o m t o p t o b o t t o m o f c o r e s f r o m 1-2 m i n t h i c k n e s s and an increase o f 2 ° / 0 0 from t h e a v e r a g e of t h e h i g h e r BA2 s a m p l e s t o t h e l o w e r BA1 s a m p l e s , a t o t a l d i s t a n c e of 6 m. A d d i t i o n a l l y , a l o n g t h e 100 m l o n g i t u d i n a l p r o f i l e o f TRC1, t h e r e was no s i g n i f i c a n t i s o t o p i c v a r i a t i o n ( a v e r a g e s a t 3 s i t e s ) . The i n i t i a l i s o t o p i c c o m p o s i t i o n o f a b a s a l r e s e r v o i r i s a f f e c t e d by i t s s o u r c e , e i t h e r b a s a l m e l t o r s u r f a c e m e l t and p r e c i p i t a t i o n . F i g u r e 21 and F i g u r e 22 i n d i c a t e t h a t i c e and snow m e l t ( b u l k i c e s a m p l e s ) have d i f f e r e n t heavy i s o t o p e c h a r a c t e r i s t i c s from s u r f a c e p r e c i p i t a t i o n . Heavy i s o t o p e s l o p e s f o r b a s a l and b u l k i c e c a n be c a l c u l a t e d f r o m t h e open and c l o s e d s y s t e m m o d e l s d e v e l o p e d by J o u z e l and Souchez (1982) and Souchez and J o u z e l (1984) ( S e c t i o n 1.3.2.2). I have c a l c u l a t e d model 80 s l o p e s f r o m E q u a t i o n s 5 and 6 a s s u m i n g t h a t an i n i t i a l r e s e r v o i r has f o r m e d from e i t h e r b u l k i c e m e l t o r p r e c i p i t a t i o n . 1 By c a l c u l a t i n g a range o f i n t e r s e c t i o n s u s i n g b u l k , m e t e o r i c and b a s a l r e l a t i o n s h i p s and t h e i r u n c e r t a i n t i e s , p a r a m e t e r s c a n be c a l c u l a t e d f o r i n p u t t o t h e e q u a t i o n s . I have u s e d t h e s e t o f f r a c t i o n a t i o n c o e f f i c i e n t s t h a t a r e l i s t e d i n F i g u r e 2. T a b l e 4 l i s t s t h e h i g h e s t s l o p e s , a s s u m i n g t h a t t h e i n i t i a l c o m p o s i t i o n s a r e t a k e n w i t h i n t h e r a n g e o f o b s e r v e d c o m p o s i t i o n s i n t h e Backe and T r a p r i d g e b a s i n s . T a b l e 4 . S l o p e s f r o m J o u z e l and S ouchez m o d e l s . S e c t i o n 1.3.2.2 and J o u z e l and S ouchez (1982) and S ouchez and J o u z e l ( 1 9 8 4 ) . E q u i l i b r i u m f r a c t i o n a t i o n f a c t o r s a r e assumed t o be arj=1.0208 and a o 1 8 = 1 . 0 0 3 w h i c h g i v e t h e h i g h e s t t h e o r e t i c a l s l o p e s . T r a p r i d g e R e s e r v o i r M e t e o r i c B a s a l M e l t Open M o d e l 5.70 5.81 S l o p e s C l o s e d Model 5.60 5.71 M e a s u r e d 6.75 ±0.28 M e t e o r i c 5.79 5.69 Backe 6.27 ± 0 . 1 7 B a s a l M e l t 5.92 5.82 Whether t h e r e s e r v o i r s o u r c e i s p r e c i p i t a t i o n or b a s a l m e l t , t h e model s l o p e s a r e l o w e r t h a n t h e f i e l d r e s u l t s . A v e r a g i n g s u r f a c e and b a s a l 6 v a l u e s s e p a r a t e l y , and a s s u m i n g m i x i n g of t h e s u r f a c e and b a s a l w a t e r , a l s o g i v e s model s l o p e s ( f r o m J o u z e l and Souchez m o d e l s ) t h a t a r e a l w a y s l e s s t h a n t h e measured v a l u e s . 1 I f t h e i n i t i a l r e s e r v o i r i s m e t e o r i c w a t e r , t h e samples a r e f ormed ' e a r l y ' b e c a u s e t h e y a r e e n r i c h e d compared t o t h e s o u r c e w a t e r , whereas t h e y a r e l i g h t e r t h a n b a s a l m e l t water and would be f o r m e d l a t e r i f t h e r e s e r v o i r was b a s a l m e l t . 81 The d i s c r e p a n c y o f m easured s l o p e s f r o m model s l o p e s c a n r e s u l t f r o m e i t h e r t h e a s s u m p t i o n o f c o n s t a n t i n i t i a l 8 v a l u e s o r t h e use o f e q u i l i b r i u m f r e e z i n g f r a c t i o n a t i o n f a c t o r s f o r b u l k w a t e r . A s s u m i n g t h e a v a l u e s f o r e q u i l i b r i u m f r e e z i n g a r e v a l i d and u s i n g t h e J o u z e l and Souchez m o d e l s , t h e i n i t i a l i s o t o p i c c o m p o s i t i o n s must be much h e a v i e r t h a n any s a m p l e s t h a t I have o b s e r v e d on T r a p r i d g e and Backe G l a c i e r s , t o p r o d u c e t h e o b s e r v e d s l o p e s . The h i g h e r s l o p e s i m p l y t h a t a f r a c t i o n a t i o n i s o c c u r r i n g w h i c h c a u s e s 5D t o change r e l a t i v e l y f a s t e r , compared t o 8 0 1 8 , t h a n i n a f r e e z i n g p r o c e s s . I f t h e r e was s u c h a f r a c t i o n a t i o n o c c u r r i n g , a would d i f f e r f r o m t h e v a l u e s c h o s e n . T h e r e i s a l s o t h e p r o b l e m a s s o c i a t e d w i t h a s s u m i n g t h a t t h e s l o p e o f t h e heavy i s o t o p e r e l a t i o n s h i p o f b a s a l i c e r e p r e s e n t s a p r o c e s s . B a s a l and b u l k i c e have p r o b a b l y e v o l v e d f r o m i s o t o p i c a l l y v a r y i n g s o u r c e s o f w a t e r , e i t h e r s u b g l a c i a l w a ter o r p r e c i p i t a t i o n , t h u s i n t e r s e c t i o n s of t h e heavy i s o t o p e r e l a t i o n s h i p s w i l l not r e p r e s e n t a common i s o t o p i c s o u r c e f r o m w h i c h b a s a l i c e has e v o l v e d . S u b g l a c i a l w a t e r p r e s s u r e measurements on g l a c i e r s i n c l u d i n g t h e T r a p r i d g e , have r a p i d v a r i a t i o n s t h a t s u g g e s t t h e s u r f a c e and s u b g l a c i a l d r a i n a g e s y s t e m s a r e c o n n e c t e d . The 6 v a l u e s o f t h e water s u p p l y would change due t o t h i s m i x i n g , and i n a d d i t i o n t h e r e may be an i s o t o p i c e f f e c t due t o f l o w t h r o u g h t h e s u b s t r a t e . T h e s e f a c t s d i s c o u r a g e t h e use of t h e 5 D / 6 0 1 8 s l o p e as a p r o c e s s i n d i c a t o r f o r s u b g l a c i a l p r o c e s s e s . 82 4.2 SUBGLACIAL ISOTOPIC PROCESSES B e f o r e p r o p o s i n g p o t e n t i a l s u b g l a c i a l p r o c e s s e s o f d e b r i s i n c o r p o r a t i o n , t h e f o l l o w i n g a s p e c t s must be c o n s i d e r e d : 1. V a r i a b i l i t y o f i s o t o p i c c o m p o s i t i o n of i n p u t w ater due t o (a) change o v e r t i m e c a u s e d by m i x i n g of s u r f a c e and b a s a l w a t e r . (b) change w i t h p o s i t i o n c a u s e d by f r e e z i n g of l a r g e f r a c t i o n s o f b a s a l w a t e r and t h e a s s o c i a t e d a l t e r a t i o n o f b a s a l w ater c o m p o s i t i o n . 2. F r e e z i n g r a t e s t h a t c a u s e n o n - e q u i l i b r i u m p r o c e s s e s . 3. F r e e z i n g f r a c t i o n a t i o n p r o c e s s e s and s u b g l a c i a l c i r c u l a t i o n e f f e c t s t h a t have n o t been i d e n t i f i e d . I t i s a l s o p o s s i b l e t h a t s a m p l i n g methods c a n a c c o u n t f o r some a s p e c t s of t h e i s o t o p i c v a r i a t i o n s . The 5 v a l u e s a r e an a v e r a g e o v e r a f i n i t e t h i c k n e s s of i c e , t h e r e b y r e s t r i c t i n g o b s e r v a t i o n s t o low f r e q u e n c y v a r i a t i o n s i n i s o t o p i c c o m p o s i t i o n . E a c h d a t a p o i n t r e p r e s e n t s a m i x t u r e of i n s t a n t a n e o u s f r a c t i o n a t i o n s t a g e s w i t h a v a r i a b l e water s u p p l y . I n f o r m a t i o n i s l o s t , but t h e 5 v a r i a t i o n s c a n s t i l l be u s e f u l f o r e x a m i n i n g f e a t u r e s of m i x i n g , f r e e z i n g r a t e s and f r a c t i o n a t i o n p r o c e s s e s . 4.2.1 MIXING PROCESSES : BASAL WATER SUPPLY S u r f a c e w a t e r , e i t h e r f r e s h p r e c i p i t a t i o n o r s u b s e q u e n t snow and i c e a b l a t i o n , e n t e r s a s u b s t r a t e from g l a c i e r m a r g i n s or t h r o u g h c h a n n e l s t h a t c o n n e c t t h e i c e s u r f a c e t o t h e bed. S u r f a c e w a t e r c a n r e m a i n s t o r e d i n snow, f i r n and i c e f o r v a r y i n g p e r i o d s 83 o f t i m e b e f o r e e n t e r i n g t h e s u b g l a c i a l s y s t e m . In t h e s u b g l a c i a l s y s t e m , s u r f a c e w ater and s t o r e d w a t e r mix w i t h b a s a l m e l t w a t e r and f l o w t h r o u g h t h e s e d i m e n t o r r o c k s u b s t r a t e , i n a s h e e t of wa t e r between t h e i c e and s u b s t r a t e , o r i n c h a n n e l s c u t i n t o t h e i c e and r o c k . I c e s e g r e g a t i o n f r o m water f l o w i n a p e r m e a b l e s u b s t r a t e o r s h e e t f l o w i s most l i k e l y t o p r o d u c e r e g u l a r and e x t e n s i v e d e b r i s l a y e r s ( r a t h e r t h a n c h a n n e l f l o w ) . The i s o t o p i c c o m p o s i t i o n of s u b g l a c i a l w a t e r i s a f f e c t e d by t h e c o m p o s i t i o n s of w a t e r s o u r c e s and d e g r e e of m i x i n g between t h e v a r i o u s w a t e r s . B a s a l m e l t i s r e l a t i v e l y c o n s t a n t i s o t o p i c a l l y , a l t h o u g h i t s c o m p o s i t i o n may v a r y w i t h l o n g i t u d i n a l and t r a n s v e r s e p o s i t i o n . S u r f a c e water c o m p o s i t i o n s a r e d e t e r m i n e d by c o n t r i b u t i o n s from d i f f e r e n t s o u r c e s : 1. W i n t e r p r e c i p i t a t i o n i s l i g h t e r t h a n summer p r e c i p i t a t i o n g e n e r a l l y ( o v e r 2 0 ° / o o v a r i a t i o n i n W h i t e h o r s e ) , so t h e i n i t i a l m e l t i n s p r i n g w i l l be l i g h t e r t h a n m e l t from l a t e r summer p r e c i p i t a t i o n . 2. Snow e v o l u t i o n p r o c e s s e s o f e v a p o r a t i o n / s u b l i m a t i o n and p e r c o l a t i o n c a u s e i n i t i a l m e l t t o be r e l a t i v e l y d e p l e t e d and l a t e r m e l t t o be e n r i c h e d due t o t h e c o n c e n t r a t i o n o f heavy i s o t o p e s i n snow, as t h e m e l t s e a s o n p r o g r e s s e s . 3. The s u r f a c e m e l t c o n t r i b u t i o n comes f r o m h i g h e r a l t i t u d e as t h e a b l a t i o n s e a s o n p r o g r e s s e s w h i c h c o n t r i b u t e s l i g h t e r water ( a l t i t u d e e f f e c t ) . 4. Water s t o r a g e i n f i r n a nd i c e d e l a y s t h e s u r f a c e c o n t r i b u t i o n t o b a s a l w a t e r . 84 B e h r e n s e t a l . ( 1 9 7 9 ) , M a r t i n e c e t a l . ( 1 9 7 5 ) , and A r n a s o n (1981) d i s c u s s t h e f o l l o w i n g v a r i a t i o n s o f 5 v a l u e s i n r u n o f f f r o m g l a c i e r s a nd g l a c i e r i z e d b a s i n s . W i n t e r r u n o f f has r e l a t i v e l y c o n s t a n t i s o t o p i c c o m p o s i t i o n s b e c a u s e t h e water c o n s i s t s m a i n l y o f b a s a l m e l t and a p o s s i b l e c o n t r i b u t i o n f r o m s t o r e d s u r f a c e w a t e r . B e c a u s e o f l a r g e c o n t r i b u t i o n s of l i g h t e r w i n t e r p r e c i p i t a t i o n , s p r i n g r u n o f f e x h i b i t s minimum 5 v a l u e s . E n r i c h m e n t i n m e l t w a t e r from snow p r o c e s s e s , and a t i m e - d e l a y e d h e a v y c o n t r i b u t i o n f r o m i c e a b l a t i o n ( w h i c h o u t w e i g h s t h e e f f e c t o f snow a b l a t i o n moving up g l a c i e r t o l i g h t e r snow) c a u s e 5 v a l u e s t o i n c r e a s e t h r o u g h o u t t h e a b l a t i o n s e a s o n . When b a s a l m e l t becomes t h e major p a r t of t h e r u n o f f a g a i n , t h e a n n u a l c y c l e i s c o m p l e t e . S i n c e t h e J o u z e l and Souchez models assume a c o n s t a n t 6 r e s e r v o i r , t h e i r m o d e l s w i l l o n l y a p p l y i n s i t u a t i o n s where i n p u t w ater r e m a i n s i s o t o p i c a l l y c o n s t a n t , f o r example: 1. A r e g e l a t i o n p r o c e s s a t b e d r o c k bumps, a s s u m i n g t h a t i c e a t a p a r t i c u l a r bump m a i n t a i n s a c o n s t a n t 6 v a l u e due t o i c e f l o w c h a r a c t e r i s t i c s . 2. P r o c e s s o f b a s a l m e l t i n one zone and f r e e z i n g i n a zone f u r t h e r d o w n - g l a c i e r ( B o u l t o n 1972). I f zone b o u n d a r i e s do not m i g r a t e t h e n t h e i s o t o p i c c o m p o s i t i o n of b a s a l w ater w i l l change w i t h p o s i t i o n b u t n ot t i m e . 3. P e r m a f r o s t p r o c e s s e s where i n p u t water i s i s o t o p i c a l l y c o n s t a n t o r a c l o s e d s y s t e m e x i s t s . I f s u r f a c e w ater e n t e r s t h e s u b g l a c i a l s y s t e m o r i f t h e i s o t o p i c c o m p o s i t i o n o f s u b g l a c i a l w a ter v a r i e s w i t h t i m e and p o s i t i o n due 85 t o t h e r m a l s h i f t s o r c h a n g e s i n f r e e z i n g z o n e s , t h e n t h e a s s u m p t i o n of a c o n s t a n t 8 r e s e r v o i r i s not v a l i d . A v a r i a b l e w a t e r s u p p l y w i l l a f f e c t t h e i s o t o p i c s t r a t i g r a p h y and can s h i f t t h e h e a v y i s o t o p e r e l a t i o n s h i p . 4.2.2 FREEZING RATES E q u i l i b r i u m f r e e z i n g f r a c t i o n a t i o n f a c t o r s a r e v a l i d f o r slow f r e e z i n g p r o c e s s e s w i t h good i s o t o p i c m i x i n g . I s o t o p i c f r a c t i o n a t i o n h a s been measured i n l a b o r a t o r y e x p e r i m e n t s w i t h f r e e z i n g r a t e s o f 1 0 _ 9 - 1 0 - 6 m s " 1 ( P o s e y and S m i t h 1957; O ' N e i l l 1968; Souchez and J o u z e l 1984). When f r e e z i n g r a t e s a r e s u i t a b l y slow and s u f f i c i e n t m i x i n g o c c u r s a t a g l a c i e r bed, t h e i s o t o p i c s t r a t i g r a p h y s h o u l d be a f f e c t e d by f r a c t i o n a t i o n . The maximum measured t h e r m a l g r a d i e n t s i n b a s a l i c e of T r a p r i d g e G l a c i e r ( s e e S e c t i o n 4.3 and T a b l e 5) g i v e a maximum f r e e z i n g r a t e o f 10~ 9 m s ~ 1 w h i c h i s s u i t a b l e f o r n e a r - e q u i l i b r i u m f r a c t i o n a t i o n t o o c c u r . The c o m p l e x i t i e s o f t h e g l a c i e r / s u b s t r a t e i n t e r f a c e may a l t e r t h e water p r o p e r t i e s so t h a t an e q u i l i b r i u m p r o c e s s i s n o t a v a l i d m o d e l . I f m i x i n g i n t h e s u b g l a c i a l s y s t e m i s i n c o m p l e t e t h e n t h e d e g r e e o f f r a c t i o n a t i o n w i l l be r e d u c e d . Good m i x i n g d u r i n g slow f r e e z i n g w i l l c a u s 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 . I f t h e c o n c e n t r a t i o n o f b u b b l e s i s p r o p o r t i o n a l t o f r e e z i n g r a t e s , c l e a r i c e s h o u l d be h e a v i e r t h a n b u b b l y i c e . A l t h o u g h t h e r e a r e many r e l a t i v e l y h eavy l a y e r s of c l e a r i c e i n Backe and T r a p r i d g e c o r e s , t h e t r e n d i s n o t c o n s i s t e n t between l a y e r s o f B u b b l y I and B u b b l y I I i c e . The maximum r a t e of I 0 " s in s ' 1 i s much s l o w e r t h a n t h e f r e e z i n g r a t e s t h a t have been measured d u r i n g f r e e z i n g o f 86 r e l a t i v e l y b u b b l e - f r e e i c e . T h i s f a c t i m p l i e s t h a t f r e e z i n g r a t e s do n o t a f f e c t t h e b u b b l e c o n c e n t r a t i o n o f b a s a l i c e i n T r a p r i d g e and Backe G l a c i e r s , u n l e s s t h e r e a r e s h o r t p e r i o d s o f a c c e l e r a t e d f r e e z i n g . The b u b b l e c o n c e n t r a t i o n w i l l be a f f e c t e d by w a t e r s o u r c e . A e r a t e d s u r f a c e w a ter o r p o s s i b l y a i r t h a t i s drawn i n t o t h e s u b s t r a t e d u r i n g t h e a c c r e t i o n p r o c e s s must be r e s p o n s i b l e f o r t h e b u b b l e c o n c e n t r a t i o n . F r e q u e n t c l e a r i c e l a y e r s i m m e d i a t e l y above d e b r i s l a y e r s s u g g e s t s t h a t d e b r i s i n c o r p o r a t i o n i s p r e c e d e d by slow f r e e z i n g o r f l o w o f water w i t h low d i s s o l v e d gas c o n c e n t r a t i o n s . 1 4.2.3 FREEZING PROCESSES In a d d i t i o n t o t h e n o n - e q u i l i b r i u m e f f e c t s o f poor m i x i n g and v a r i a b l e f r e e z i n g r a t e s , t h e s o i l p hase may i n f l u e n c e t h e i s o t o p i c f r a c t i o n a t i o n d u r i n g f r e e z i n g . I w i l l examine t h e i s o t o p i c e f f e c t s of t h e f o l l o w i n g b a s a l f r e e z i n g p r o c e s s e s t h a t I s u g g e s t e d i n S e c t i o n 1.4: 1 . D i r e c t f r e e z i n g 2. P r i m a r y and s e c o n d a r y h e a v i n g . The major d i f f e r e n c e between t h e p r o c e s s e s i s t h e s t a t e o f t h e w a t e r m o l e c u l e s . In d i r e c t f r e e z i n g , w a ter i s a v a i l a b l e d i r e c t l y a t t h e i c e s u r f a c e ; i n p r i m a r y h e a v i n g , water i s drawn t o t h e i c e s u r f a c e by a c a p i l l a r y mechanism; i n s e c o n d a r y h e a v i n g , t h e water moves t o t h e i c e s u r f a c e a l o n g a f r e e e n e r g y g r a d i e n t i n an a d s o r b e d l a y e r between i n t e r s t i t i a l i c e and s o i l g r a i n s . ' C l e a r i c e w i l l f o r m i f t h e water i s u n d e r s a t u r a t e d i n a i r v a p o u r o r i f t h e f r e e z i n g r a t e i s slow enough t o c a u s e r e j e c t i o n o f t h e d i s s o l v e d g a s e s a h e a d o f t h e f r e e z i n g plane.When t h e water becomes s a t u r a t e d , b u b b l e s w i l l f o r m . 87 4.2.3.1 D i r e c t F r e e z i n g D i r e c t f r e e z i n g d e s c r i b e s f r e e z i n g f r o m a s u b g l a c i a l s y s t e m w i t h w ater c i r c u l a t i n g a t t h e i c e / s u b s t r a t e i n t e r f a c e . B e c a u s e of s h e e t f l o w o r i n t e r s t i t i a l f l o w i n a s a t u r a t e d s u b s t r a t e , w ater a t t h e i n t e r f a c e w i l l have p r o p e r t i e s s i m i l a r t o b u l k w a t e r . V a r i a t i o n s i n i s o t o p i c c o m p o s i t i o n of b a s a l i c e w i l l depend upon t h e c o m p o s i t i o n o f t h e i n p u t w a t e r , t h e r a t e of i n p u t and f r e e z i n g , and t h e l o n g i t u d i n a l p o s i t i o n u nder t h e g l a c i e r ( i f t h e b a s a l w a t e r c o m p o s i t i o n v a r i e s w i t h p o s i t i o n ) . I f t h e b a s a l w a t e r i s o t o p i c c o m p o s i t i o n and f r e e z i n g f r a c t i o n a t i o n p r o c e s s do not change w i t h p o s i t i o n o r t i m e , t h e heavy i s o t o p e r e l a t i o n s h i p w i l l r e p r e s e n t t h e f r a c t i o n a t i o n p r o c e s s ( e q u i l i b r i u m o r n o n - e q u i l i b r i u m ) . I f t h e r e i s change w i t h t i m e , t h e heavy i s o t o p e r e l a t i o n s h i p w i l l be a measurement o f a s e t o f sam p l e s w h i c h have e v o l v e d a l o n g d i f f e r e n t heavy i s o t o p e p a t h s on a 5D v e r s u s S O 1 8 p l o t . 4.2.3.2 P r i m a r y and S e c o n d a r y H e a v i n g B e c a u s e o f t h e p r e s s u r e d r o p a c r o s s a c u r v e d i c e / w a t e r i n t e r f a c e , w a ter can move t o t h e i n t e r f a c e by a c a p i l l a r y mechanism ( W i l l i a m s 1968; M i l l e r 1980). T h i s p r i m a r y h e a v i n g p r o c e s s c a u s e s i c e t o form a t a s o i l / i c e i n t e r f a c e . P o r e w a t e r i s under s u c t i o n and t h e s u b s t r a t e i s s a t u r a t e d . The b u l k o f t h e c a p i l l a r y w a t e r i s p r o b a b l y n o t i s o t o p i c a l l y a f f e c t e d by s u r f a c e f o r c e s . I t i s p o s s i b l e f o r t h e i c e t o i n t r u d e i n t o t h e s o i l m a t r i x by r e g e l a t i o n when o v e r b u r d e n and water p r e s s u r e c o n d i t i o n s a r e s u c h t h a t p r e s s u r e m e l t i n g o c c u r s . The i s o t o p i c c o m p o s i t i o n of t h e i n t e r s t i t i a l i c e t h a t i s f o r m i n g w i l l be 88 d e p e n d e n t upon t h e i n t e r a c t i o n s and i n i t i a l c o m p o s i t i o n s of t h e r e g e l a t i n g i c e and i n t e r s t i t i a l w a t e r . The c h a n g e s i n i s o t o p i c c o m p o s i t i o n o f b a s a l i c e i n g l a c i e r s w o u l d p r o b a b l y depend upon t h e b a s a l w a t e r s u p p l y v a r i a t i o n s . I f t h e r e g e l a t i n g i c e do e s n o t mix w i t h t h e b a s a l w a t e r , t h e r e may be some i n c r e a s e i n heavy i s o t o p e c o m p o s i t i o n b e c a u s e o f t h e p r e f e r e n t i a l f r a c t i o n a t i o n d u r i n g f r e e z i n g . T h i s a f f e c t would p r o b a b l y be s m a l l . In t h e s e c o n d a r y h e a v i n g p r o c e s s , an a d s o r p t i o n l a y e r between s o i l and p o r e i c e forms a c o n t i n u o u s f i l m between an i c e l e n s and a water t a b l e . A l t h o u g h c o n t r o v e r s y e x i s t s o v e r t h e mechanism o f w a t e r movement t h r o u g h f r o z e n s o i l , s u c h a movement i s w e l l e s t a b l i s h e d . The two b a s i c t h e o r i e s a r e t h e r i g i d i c e model ( M i l l e r 1980; O ' N e i l l and M i l l e r 1982) and t h e a d s o r b e d f o r c e model ( T a k a g i 1980). B o t h models assume t h a t a f r o z e n f r i n g e f orms w i t h i n t e r s t i t i a l i c e o c c u p y i n g a l l o f t h e p o r e s p a c e e x c e p t f o r a t h i n f i l m o f a d s o r b e d w a t e r . B e c a u s e o f a f r e e e n e r g y g r a d i e n t a c r o s s t h e f r o z e n f r i n g e , w a ter f l o w s t o an i c e l e n s t h r o u g h t h e c o n t i n u o u s f i l m . 1 V a r i o u s m o d e l s of c o u p l e d h e a t and mass t r a n s f e r b a s e d on c a p i l l a r y o r s e c o n d a r y h e a v i n g p r o c e s s e s have been d e v e l o p e d ( H a r l a n 1971, 1973; O u t c a l t 1980; O ' N e i l l and M i l l e r 1982; O ' N e i l l (1983) p r o v i d e s a r e v i e w of m o d e l l i n g e f f o r t s ) . P r i m a r y h e a v i n g i s u n a b l e t o e x p l a i n t h e l a r g e h e a v i n g p r e s s u r e s and i c e l e n s i n g b e h i n d a f r e e z i n g f r o n t t h a t a r e o b s e r v e d i n p e r m a f r o s t . C o n s e q u e n t l y , s t u d i e s a r e c o n c e n t r a t i n g on s e c o n d a r y h e a v i n g and t h e mechanisms o f water movement i n f r o z e n s o i l s . 1 T h i s g r a d i e n t i s v a r i o u s l y d e s c r i b e d a s - a p r e s s u r e , t e m p e r a t u r e , or i c e c o n t e n t g r a d i e n t . 89 Two c o n t r o v e r s i a l a s p e c t s of t h e t h e o r y o f s e c o n d a r y h e a v i n g a r e t h e s t a t e o f t h e a d s o r b e d w a t e r and t h e r o l e o f i c e r e g e l a t i o n i n movement of s o l i d i c e t o w a r d a g r o w i n g i c e l e n s . M i l l e r (1980) d e v e l o p s a thermodynamic b a s i s f o r an e f f e c t i v e f l o w o f i c e by r e g e l a t i o n a l o n g a t e m p e r a t u r e g r a d i e n t i n a f r o z e n f r i n g e . An a s s o c i a t e d f l o w o f a d s o r b e d w a t e r c o n t r i b u t e s mass t o t h e g r o w i n g i c e l e n s and t h e i n t e r s t i t i a l i c e i n t h e f r o z e n f r i n g e . The a d s o r b e d f o r c e t h e o r y a l s o p r e d i c t s f l o w of a d s o r b e d w a t e r t o an i c e l e n s , b u t t h e r e i s no i c e movement t h r o u g h t h e f r o z e n f r i n g e . To c o n s i d e r t h e i s o t o p i c e f f e c t s of s e c o n d a r y h e a v i n g , I i n i t i a l l y assume t h a t t h e r e i s no i c e movement t h r o u g h t h e f r o z e n f r i n g e . T h i s s i m p l i f i c a t i o n i m p l i e s t h a t p o r e i c e forms i n s i t u . The f r e e z i n g p r o c e s s w i l l be complex s i n c e w ater c a n e x i s t i n t h r e e s t a t e s , f r o z e n , a d s o r b e d , and c a p i l l a r y . Heavy i s o t o p e s s h o u l d be p r e f e r e n t i a l l y a d s o r b e d t o s o i l g r a i n s , however, as t e m p e r a t u r e d r o p s and i c e s t a r t s t o form, t h e r e i s a l o w e r f r e e e n e r g y s t a t e t o w h i c h t h e heavy i s o t o p e s c an move. I t i s d i f f i c u l t t o q u a n t i f y t h e i s o t o p i c e f f e c t s , but t h e f r a c t i o n o f water m o l e c u l e s t h a t a r e a f f e c t e d by s u r f a c e f o r c e s i s p r o b a b l y s m a l l s i n c e t h e r e i s o n l y a s m a l l f r a c t i o n o f f i n e m a t e r i a l ( w h i c h a c c o u n t s f o r most o f t h e s p e c i f i c s u r f a c e a r e a ) i n t h e s u b s t r a t e ( S e c t i o n 3.4). C o n s e q u e n t l y , t h e i n i t i a l f r a c t i o n a t i o n d u r i n g i c e f o r m a t i o n i n t h e p o r e s may be an e q u i l i b r i u m p r o c e s s . As p o r e s f i l l w i t h i c e , and water b e g i n s t o f l o w i n t h e a d s o r b e d f i l m , s u r f a c e f o r c e s s h o u l d i s o t o p i c a l l y a f f e c t t h e f l o w i n g w a t e r . U l t r a f i l t r a t i o n i n c l a y s o i l s c a u s e s f l o w 90 r e t a r d a t i o n o f t h e h e a v y i s o t o p e s o f w a t e r . A f r o z e n f r i n g e w i t h t h i n a d s o r b e d l a y e r s , s h o u l d c a u s e p r e f e r e n t i a l f l o w o f t h e l i g h t e r i s o t o p i c s p e c i e s . U l t r a f i l t r a t i o n a c t s i n an o p p o s i t e s e n s e t o t h e f r e e z i n g f r a c t i o n a t i o n and t h e r e s i d u a l w a ter s h o u l d be e n r i c h e d a s f l o w c o n t i n u e s . I f t h e r e s i d u a l w a t e r i s n o t mixed w i t h o t h e r i n p u t w a t e r s , t h e l a y e r s of i c e w i l l be p r o g r e s s i v e l y e n r i c h e d . I f e n r i c h e d r e s i d u a l w a ter f l o w s d o w n - g l a c i e r t h e n i c e l a y e r s w i l l be p r o g r e s s i v e l y e n r i c h e d as t h e d i s t a n c e f r o m t h e s o u r c e i n c r e a s e s . Slow f r e e z i n g r a t e s o r m i x i n g w i t h i n p u t w a t e r s may mask an u l t r a f i l t r a t i o n p r o c e s s . I f M i l l e r ' s h y p o t h e s i s o f i c e f l o w by r e g e l a t i o n i s t r u e , t h e i s o t o p i c p r o c e s s becomes co m p l e x . I c e must r e g e l a t e t o f l o w t h r o u g h t h e p o r e c o n s t r i c t i o n s c a u s i n g i s o t o p i c e xchange w i t h f i l m w a t e r . I s o t o p i c c o m p o s i t i o n s i n t h e f r o z e n f r i n g e w i l l d e pend upon f r e e z i n g r a t e , 6 v a r i a t i o n s i n t h e w a ter s u p p l y , and e x c h a n g e mechanisms d u r i n g r e g e l a t i o n . B e c a u s e o f t h e c o n t r o v e r s y o f w a t e r and i c e c h a r a c t e r i s t i c s and movement i n s e c o n d a r y h e a v i n g , a s t u d y of i s o t o p i c c o m p o s i t i o n s i n i c e l e n s e s and t h e f r o z e n f r i n g e may r e s o l v e t h e f l o w and s u r f a c e e f f e c t s . 4.3 DEBRIS ENTRAINMENT AND ICE ACCRETION The p r o c e s s e s t h a t w i l l a f f e c t t h e i s o t o p i c s t r a t i g r a p h y and h eavy i s o t o p i c r e l a t i o n s h i p s a r e summarized i n F i g u r e 7. T h e r m a l and h y d r o l o g i c a l c o n d i t i o n s a t t h e g l a c i e r bed c o n t r o l t h e a c c r e t i o n and f r a c t i o n a t i o n p r o c e s s e s . Some of t h e c o n d i t i o n s n e c e s s a r y f o r b a s a l a c c r e t i o n c a n be i n f e r r e d f r o m t h e f o l l o w i n g p r o p e r t i e s o f Backe and T r a p r i d g e G l a c i e r s : 91 1. V a r i a b l e t h i c k n e s s of i c e between d e b r i s l a y e r s , r a n g i n g f r o m 1-60 cm. 2. D e b r i s l a y e r s w i t h l a r g e l a t e r a l and l o n g i t u d i n a l d i m e n s i o n s ( h u n d r e d s o f m e t r e s ) , t h a t a r e a p p r o x i m a t e l y p a r a l l e l t o t h e bed e x c e p t where f o l d i n g has o c c u r r e d , e . g . Backe G l a c i e r . 3. R e s i d e n c e t i m e o f i c e p r o b a b l y l e s s t h a n 300 y e a r s w h i c h p r o v i d e s a t i m e s c a l e f o r f r e e z i n g . 4. Backe G l a c i e r has more t h a n 50 d e b r i s l a y e r s i n 15 m o f b a s a l i c e , and T r a p r i d g e G l a c i e r has more t h a n 20 d e b r i s l a y e r s i n 5 m of b a s a l i c e ; t h e b a s a l i c e l a y e r s r e p r e s e n t a p p r o x i m a t e l y h a l f o f t h e r e m a i n i n g i c e t h i c k n e s s i n t h e a b l a t i n g l o w e r z o n e s . The s i m p l e s t a c c r e t i o n mechanism i s i n c o r p o r a t i o n o f a d e b r i s l a y e r as t h e f r e e z i n g i s o t h e r m m i g r a t e s d o w n - g l a c i e r ( l o n g i t u d i n a l l y ) between s u r g e s . The b u l g e a p p r o x i m a t e l y d e l i n e a t e s c o l d bed and t e m p e r a t e bed z o n e s on T r a p r i d g e . T h i s f a c t i m p l i e s t h a t t h e i n t e r s e c t i o n o f t h e f r e e z i n g i s o t h e r m and t h e g l a c i e r bed m i g r a t e s d o w n - g l a c i e r w i t h t h e t h i c k e n i n g of t h e i c e . The s e c o n d frame i n F i g u r e 4 i l l u s t r a t e s t h e i n t e r s e c t i o n o f t h e f r o z e n and u n f r o z e n bed. I f b a s a l f r e e z i n g o c c u r s o n l y a t t h e b o u n d a r y between f r o z e n and u n f r o z e n bed t h e n one d e b r i s l a y e r c o u l d g r a d u a l l y be i n c o r p o r a t e d i n t o t h e i c e between e a c h s u r g e . B e c a u s e o f t h e l a r g e number of d e b r i s l a y e r s and r e l a t i v e l y s h o r t r e s i d e n c e t i m e e x p e c t e d f o r b a s a l i c e , t h i s p r o c e s s c o u l d not have i n c o r p o r a t e d t h e many l a y e r s , u n l e s s modern c o n d i t i o n s a r e 92 s i g n i f i c a n t l y d i f f e r e n t t h a n i n t h e p a s t . 1 B o u l t o n (1983) o u t l i n e s some o f t h e t h e r m a l and h y d r o l o g i c a l c o n d i t i o n s t h a t d e f i n e z o n e s o f b a s a l m e l t i n g and f r e e z i n g . He s u g g e s t s t h a t b a s a l h e a t f l u x c o n s i s t s o f t h r e e s o u r c e s , g e o t h e r m a l h e a t , l a t e n t h e a t of f r e e z i n g , and h e a t p r o d u c t i o n due t o b a s a l s l i d i n g . C l a r k e e t a l . (1984) s u g g e s t e d an a d d i t i o n a l h e a t s o u r c e due t o r e l e a s e of g r a v i t a t i o n a l e n e r g y by t h e s u b g l a c i a l w a t e r s y s t e m . T h i s s u g g e s t i o n was made b e c a u s e of t h e h i g h t h e r m a l g r a d i e n t s t h a t were o b s e r v e d i n T r a p r i d g e G l a c i e r . They c a l c u l a t e d t h a t g r a v i t a t i o n a l e n e r g y r e l e a s e e q u i v a l e n t t o f l o w of a s m a l l s t r e a m c o u l d a c c o u n t f o r t h e b a s a l h e a t f l u x a t t h e T r a p r i d g e b e d . T h e r m a l e n e r g y i s removed by h e a t c o n d u c t i o n t h r o u g h t h e i c e and p o s s i b l y by a d v e c t i o n i n t h e b a s a l water f l u x a n d i c e f l o w . The f r e e z i n g r a t e w i l l be d e p e n d e n t upon t h e t o t a l f l u x f r o m g e o t h e r m a l , g r a v i t a t i o n a l and s l i d i n g h e a t s o u r c e s , s i n c e l a t e n t h e a t r e l e a s e i s i n c o m p e t i t i o n w i t h t h e s e s o u r c e s . I f t h e r e i s a l a r g e g r a v i t a t i o n a l r e l e a s e f r o m h i g h s u b g l a c i a l w a t e r f l u x , t h e n f r e e z i n g r a t e s would be low and n e t m e l t i n g m i g h t o c c u r a t t h e bed. In c o n t r a s t , f a s t f r e e z i n g o r slow water s u p p l y may c a u s e t h e g l a c i e r t o f r e e z e t o i t s b e d . 2 T a b l e 5 . T h e r m a l c a l c u l a t i o n s f o r T r a p r i d g e G l a c i e r . The t h e r m a l p r o p e r t i e s were d e t e r m i n e d u s i n g d a t a from measurements on T r a p r i d g e G l a c i e r . Maximum b a s a l f r e e z i n g r a t e s were c a l c u l a t e d by a s s u m i n g t h a t a l l of t h e b a s a l h e a t f l u x was due t o r e l e a s e o f ^ h e modern s u r g e c y c l e o f T r a p r i d g e and Backe G l a c i e r s i s a p p r o x i m a t e l y 40 y e a r s , t h u s a c c r e t i o n o f numerous d e b r i s l a y e r s i s n o t l i k e l y by t h i s mechanism. 2 T h e f r e e z i n g p l a n e w i l l a d v a n c e i n t o t h e bed i f h e a t s o u r c e s i n c l u d i n g l a t e n t h e a t p r o d u c t i o n , do n o t e x c e e d t h e c a p a c i t y of h e a t r e m o v a l p r o c e s s e s i n c l u d i n g c o n d u c t i o n and a d v e c t i o n ) . 93 l a t e n t h e a t . S i t e T h e r m a l G r a d i e n t T h e r m a l F l u x (W n r 2 ) 0.567 0.646 0.662 0. 168 0.269 0.244 0.231 F r e e z i n g R a te (cm a " 1 ) 2 3 3.5 6 8 1 1 1 3 ( ° C rn"1) 0.270 0.308 0.315 0.080 0. 128 0.116 0.110 5.93 6.77 7.03 1 .76 2.81 2.55 2.42 I have u s e d t h e r m a l c h a r a c t e r i s t i c s o f T r a p r i d g e G l a c i e r t o c a l c u l a t e f r e e z i n g r a t e s by a s s u m i n g t h a t a l l o f t h e h e a t f l u x i s due t o a l a t e n t h e a t c o n t r i b u t i o n . T a b l e 5 shows t h a t w i t h t h e h i g h e s t o b s e r v e d t h e r m a l g r a d i e n t s , t h e maximum r a t e of i c e f o r m a t i o n w o u l d be a p p r o x i m a t e l y 7 cm a " 1 . B e c a u s e t h e r e a r e i c e l a y e r s up t o 60 cm t h i c k between d e b r i s l a y e r s on Backe and T r a p r i d g e , s e v e r a l p o s s i b i l i t i e s a r e s u g g e s t e d : 1. I n c o r p o r a t i o n of a d e b r i s l a y e r does n o t a l w a y s o c c u r on an a n n u a l c y c l e . 2. T h e r m a l g r a d i e n t s d u r i n g i c e f o r m a t i o n were much h i g h e r t o i n c o r p o r a t e one d e b r i s l a y e r p e r y e a r . 3. D e c e l e r a t i o n and s t r a i n d e f o r m a t i o n of t h e i c e f r o n t c a u s e d t h i c k e n i n g between d e b r i s l a y e r s . S i n c e t h e t h i c k n e s s o f t h e b a s a l l a y e r s d o e s n o t change s i g n i f i c a n t l y o v e r t h e 100 m l e n g t h o f TRC1, f l o w - r e l a t e d e f f e c t s do n o t seem t o be i m p o r t a n t i n c a u s i n g t h e t h i c k e r l a y e r s . The t h e r m a l g r a d i e n t of a g l a c i e r i s a c r i t i c a l f a c t o r i n t h e b a s a l i n t e r a c t i o n s . The s u r g e i n s t a b i l i t y may i n t r o d u c e an i m p u l s e 94 t h e r m a l g r a d i e n t change a t t h e i n t e r f a c e . T h i s change o c c u r s a f t e r a s u r g e b e c a u s e b a s a l i c e f r o m t h e a c c u m u l a t i o n zone moves d o w n - g l a c i e r t o a p o s i t i o n o v e r s u b s t r a t e i n t h e low e r g l a c i e r . W i t h t h e s u r f a c e t e m p e r a t u r e r e m a i n i n g a p p r o x i m a t e l y t h e same and t h e b a s a l t e m p e r a t u r e s t i l l n e a r f r e e z i n g , t h i n n i n g of t h e g l a c i e r i n some a r e a s and t h i c k e n i n g i n o t h e r a r e a s , a f t e r s u r g i n g c a u s e s a change i n t h e t h e r m a l g r a d i e n t . In t h e t h i n n e d a r e a s , t h e i n c r e a s e d t h e r m a l g r a d i e n t and c o r r e s p o n d i n g p r e s s u r e c h ange a t t h e bed enhance b a s a l f r e e z i n g . Even w i t h i n c r e a s e d t h e r m a l g r a d i e n t s , t h e b o u n d a r y t e m p e r a t u r e s make i n c o r p o r a t i o n o f a 60 cm i c e l a y e r i n 1 y e a r , i m p o s s i b l e i n T r a p r i d g e and Backe G l a c i e r s . In p e r m a f r o s t , s e g r e g a t e d i c e forms as l o n g as a water s u p p l y i s m a i n t a i n e d t o a f r e e z i n g f r o n t . The f r e e z i n g p l a n e a d v a n c e s i n t o t h e s u b s t r a t e when water f l o w i s r e d u c e d s u f f i c i e n t l y t o r e d u c e l a t e n t h e a t r e l e a s e and a l l o w t h e advancement. Water f l o w a t a s u r g i n g g l a c i e r bed c a n v a r y w i t h an a n n u a l s u b g l a c i a l w a t e r c y c l e and a l o n g e r s u r g e c y c l e . T h r o u g h o u t t h e w i n t e r , a r e l a t i v e l y c o n s t a n t w ater f l o w i s m a i n t a i n e d by s u b g l a c i a l m e l t and r e l e a s e o f s t o r e d s u r f a c e a b l a t i o n . 1 Water f l u x w i l l i n c r e a s e t o a maximum d u r i n g t h e a b l a t i o n p e r i o d . The c a p a c i t y o f t h e s y s t e m i s n o t known, b u t o b s e r v a t i o n s d u r i n g T r a p r i d g e d r i l l i n g s u g g e s t s t h a t t h e r e a r e two f l o w s u b - s y s t e m s . One s u b - s y s t e m i s c h a n n e l f l o w w h i c h may be i n d i c a t e d by immediate d r a i n a g e o f some d r i l l h o l e s upon 1 T h i s c o n c l u s i o n i s s u p p o r t e d by b u i l d u p of w i n t e r i c e below t h e s t a g n a n t T r a p r i d g e i c e . A s e c t i o n o f i c e a p p r o x i m a t e l y 6000 m 3 (2 m t h i c k ) f o r m e d d u r i n g t h e w i n t e r o f 1984-1985, a l t h o u g h t h e wa t e r may have come from l a t e s e a s o n s u r f a c e m e l t . 95 c o n n e c t i o n t o t h e bed. The s e c o n d s u b - s y s t e m i s f l o w t h r o u g h t h e s u b s t r a t e w h i c h i s c o n t r o l l e d by t h e p e r m e a b i l i t y o f t h e s u b s t r a t e . As a m e l t s e a s o n p r o g r e s s e s , w ater s u p p l y i s r e d u c e d t o w i n t e r f l o w r a t e s . H i g h e r summer f l o w w i l l r e l e a s e more g r a v i t a t i o n a l e n e r g y t h a n w i n t e r f l o w , c a u s i n g an a n n u a l c y c l e o f b a s a l h e a t f l u x . T r a p r i d g e t e m p e r a t u r e measurements do n o t i n d i c a t e an a n n u a l b a s a l h e a t f l u x c y c l e , t h e r e f o r e , v a r i a b l e c o n t r i b u t i o n s f r o m l a t e n t h e a t p r o d u c t i o n , b a s a l s l i d i n g and g r a v i t a t i o n a l h e a t r e l e a s e , and a s t e a d y c o n t r i b u t i o n f r o m g e o t h e r m a l h e a t c o u l d m a i n t a i n a s t e a d y t o t a l h e a t f l u x . D u r i n g i n c r e a s e d summer f l o w , g r a v i t a t i o n a l e n e r g y r e l e a s e i n c r e a s e s , b a s a l f r e e z i n g d e c r e a s e s , and t h e l a t e n t h e a t p r o d u c t i o n d r o p s . T h i s c y c l e s u g g e s t s t h a t r a t e s o f i c e a c c r e t i o n w i l l v a r y d u r i n g t h e y e a r , d e c r e a s i n g a s t h e s e a s o n a l w ater f l o w i n c r e a s e s and i n c r e a s i n g a s t h e b a s a l w ater s u p p l y d e c r e a s e s . The maximum f r e e z i n g r a t e w i l l d epend m a i n l y upon t h e d i s s i p a t i o n of h e a t by c o n d u c t i o n . B a s a l d e b r i s e n t r a i n m e n t by f r e e z i n g p l a n e advancement c a n o c c u r w i t h a c c e l e r a t e d f r e e z i n g , a d e c r e a s e i n t h e water s u p p l y or by i n t r u s i o n o f i c e i n t o t h e s u b s t r a t e ( s e e F i g u r e 2 7 ) . D i r e c t f r e e z i n g and p r i m a r y h e a v i n g p r o c e s s e s c o u l d i n c o r p o r a t e i c e a nd d e b r i s a t t h e bed on t h e a n n u a l b a s a l w a t e r c y c l e i f c o n d i t i o n s l e a d t o s u i t a b l e r a t e s o f f r e e z i n g o r water f l o w . A f t e r a s u r g e , an i n c r e a s e d b a s a l w ater s u p p l y may be m a i n t a i n e d f o r many y e a r s b e c a u s e of t h e c r e v a s s e d g l a c i e r s u r f a c e . H i g h t h e r m a l g r a d i e n t s c a u s e d by g l a c i e r t h i n n i n g c o m b i n e d w i t h t h e 96 i n c r e a s e d w a t e r s u p p l y c o u l d l e a d t o a c c r e t i o n o f t h i c k i c e l a y e r s . As s u g g e s t e d above, t h e i s o t o p i c l a y e r i n g of t h e s e p r o c e s s e s i s most d e p e n d e n t upon t h e c o m p o s i t i o n o f t h e b a s a l w ater s y s t e m . Changes on a s m a l l e r s c a l e c a u s e d by r e g e l a t i o n w ould 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 t h e b a s a l water v a r i a t i o n s . The p r e f e r r e d p r o c e s s e s t h a t can p r o d u c e o b s e r v e d i s o t o p i c c o m p o s i t i o n s a r e summarized a t t h e end o f t h e c h a p t e r . The f o r m u l a t i o n of t h e s e c o n d a r y h e a v i n g p r o c e s s i m p l i c i t l y i n c l u d e s a d e b r i s e n t r a i n m e n t mechanism. A l t h o u g h t h e r e i s no c e r t a i n t y t h a t s e c o n d a r y h e a v i n g i n c o r p o r a t e s i c e and d e b r i s a t a g l a c i e r bed, i t has been a p p l i e d t o p e r m a f r o s t p r o b l e m s t h a t have s i m i l a r i t i e s t o t h e b a s a l s y s t e m . D e b r i s e n t r a i n m e n t i s d e p e n d e n t upon p o r e p r e s s u r e i n t h e f r o z e n f r i n g e . A c c o r d i n g t o h e a v i n g t h e o r y , t h e c o m b i n e d water and i c e p r e s s u r e i n t h e p o r e s of t h e f r o z e n f r i n g e w i l l e x c e e d t h e o v e r b u r d e n p r e s s u r e a t a l o c a t i o n below an a c t i v e i c e l e n s . S e d i m e n t w i l l be i n c o r p o r a t e d by t h e u p w a r d l y moving p o r e i c e and a new l e n s w i l l b e g i n t o form where t h e p r e s s u r e i s g r e a t e r t h a n o v e r b u r d e n ( F i g u r e 2 8 ) . To examine t h e e f f e c t s o f t h i s p r o c e s s f o r g l a c i a l p a r a m e t e r s , I u s e d a q u a s i - s t a t i c model o f s e c o n d a r y h e a v i n g from H o l d e n ( 1 9 8 4 ) . The H o l d e n model i s a s i m p l i f i c a t i o n o f t h e O ' N e i l l and M i l l e r (1982) n u m e r i c a l m o d e l . H o l d e n assumes t h a t f r e e z i n g i s a slow p r o c e s s and s i m p l i f i e s a s y s t e m of p a r t i a l d i f f e r e n t i a l e q u a t i o n s i n t o two o r d i n a r y d i f f e r e n t i a l e q u a t i o n s . O ' N e i l l and M i l l e r (1982) u s e d t h e i r model t o s i m u l a t e c y c l i c a l f r o s t h e a v i n g i n p e r m a f r o s t e x p e r i m e n t s . H e a v i n g i s i n i t i a l l y s u p p r e s s e d due t o o v e r b u r d e n , but a s t h e f r o z e n f r i n g e e x p a n d s , i c e l e n s e s grow and become 97 F i g u r e 27. D e b r i s i n c o r p o r a t i o n by f r e e z i n g p l a n e advancement. The water t a b l e can be a t t h e base of t h e i c e l e n s o r below t h e l e n s w i t h w ater f l o w t o t h e l e n s by c a p i l l a r y r i s e a s i n t h e f i r s t p i c t u r e . The i c e l e n s c o n t i n u e s t o grow u n t i l water f l o w c e a s e s p o s s i b l y b e c a u s e of a d r o p i n the water t a b l e . The f r e e z i n g p l a n e a d v a n c e s and i n c o r p o r a t e s d e b r i s u n t i l water f l o w i n i t i a t e s a new l e n s a t t h e f r e e z i n g p l a n e . F a s t f r e e z i n g p l a n e advancement due t o l o w e r h e a t f l u x c o n t r i b u t i o n from r e d u c e d b a s a l w ater f l o w c a n a l s o l e a d t o i n c o r p o r a t i o n of d e b r i s . Freezing Plane Advancement • Ice Lens Unfrozen Soil Freezing Front — Water table 98 F i g u r e 28. D e b r i s i n c o r p o r a t i o n by s e c o n d a r y h e a v i n g . 1. A f r o z e n f r i n g e d e v e l o p s i n t h e s u b s t r a t e and water f l o w s t o a l e n s i n g f r o n t t h r o u g h c o n t i n u o u s c h a n n e l s of water a d s o r b e d t o t h e s o i l p a r t i c l e s . The p o r e p r e s s u r e of i c e and water i n c r e a s e s u n t i l t h e o v e r b u r d e n i s e x c e e d e d below th e l e n s i n g f r o n t . 2. A new i c e l e n s b e g i n s t o form a t t h i s l e v e l . 3. As t h e new i c e l e n s grows, a d e b r i s l a y e r i s i n c o r p o r a t e d . D u r i n g t h e d e v e l o p m e n t o f t h e d e b r i s s e q u e n c e , t h e water t a b l e may v a r y . Secondary Heaving Lensing Front 99 p r o g r e s s i v e l y t h i c k e r w i t h l o n g e r i n t e r v a l s between i n i t i a t i o n . I o u t l i n e t h e model and t h e r e s u l t s o f my c a l c u l a t i o n s i n A p p e n d i x I I . I e x amined t h e e f f e c t s of d i f f e r e n t o v e r b u r d e n p r e s s u r e s and b a s a l s t e p t e m p e r a t u r e s on h e a v i n g . As e x p e c t e d , g r e a t e r o v e r b u r d e n p r e s s u r e s s u p p r e s s e d h e a v i n g f o r a l o n g e r p e r i o d t h a n f o r t h i n n e r i c e , c a u s i n g l e s s h e a v e b ut g r e a t e r p e n e t r a t i o n o f t h e f r e e z i n g f r o n t . T h e r e i s a s i m i l a r e f f e c t when t h e b a s a l i c e t e m p e r a t u r e i s v a r i e d . One y e a r o f s e c o n d a r y h e a v i n g c a u s e d c u m u l a t i v e h e a v e s from 5 t o 11 cm f o r i c e t h i c k n e s s e s r a n g i n g f r o m T r a p r i d g e m e d i a l i c e t o m a r g i n a l i c e , and f o r bed t e m p e r a t u r e s from -1 t o -3 °C. The i c e l a y e r s a r e t h i n , however, and t h e d e p t h o f p e n e t r a t i o n i n t o t h e s u b s t r a t e r a n g e d f r o m a p p r o x i m a t e l y 1 m t o 4.5 m. In t h i s s i t u a t i o n , t h e s u b s t r a t e would p r o b a b l y move a s p a r t of t h e g l a c i e r . S e c o n d a r y h e a v i n g i n c o r p o r a t e s many t h i n i c e l e n s e s , and t h e i c e l e n s t h i c k n e s s does n o t become s i g n i f i c a n t (on a b a s a l i c e l a y e r s c a l e ) u n t i l s e v e r a l months o f f r e e z i n g . Even a f t e r a y e a r t h e i c e l a y e r t h i c k n e s s i s n o t n e a r t h e maximum 60 cm l a y e r s . The s e c o n d a r y h e a v i n g p r o c e s s i s n o t r e s t r i c t e d t o an a n n u a l p e r i o d . I n c o r p o r a t i o n o f t h i c k i c e l a y e r s c an o c c u r i f t h e p r o c e s s c o n t i n u e s f o r l o n g e r p e r i o d s . The c u m u l a t i v e heave a f t e r t e n y e a r r u n s o f t h e model was g r e a t e r t h a n 80 cm, but t h e d e p t h of p e n e t r a t i o n b a l l o o n e d t o a p p r o x i m a t e l y 10 m. B e c a u s e of i t s r e l a t i v e m a t h e m a t i c a l s i m p l i c i t y and c o m p l e t e n e s s , t h e M i l l e r model o f s e c o n d a r y h e a v i n g i s a s e d u c t i v e a p p r o a c h t o b a s a l f r e e z i n g p r o c e s s e s . A t a g l a c i e r bed, 100 g l a c i e r m o t i o n , v a r i a b l e w ater s u p p l y and p r e s s u r e w i l l i n f l u e n c e t h e h e a v i n g mechanism. I have n o t i n c o r p o r a t e d s e a s o n a l w ater v a r i a t i o n s i n t o t h e model and I e m p h a s i z e t h a t I have made o n l y a p r e l i m i n a r y a p p r o a c h t o c o n s i d e r i n g an a c c r e t i o n mechanism of s e c o n d a r y h e a v i n g . One of my i n t e r e s t s i n a p p l y i n g t h e model was t o d e t e r m i n e i f t h e l a c k o f b a s a l s e d i m e n t i n t h e m e l t w a t e r t u n n e l i n t h e T r a p r i d g e m e d i a l i c e c o u l d be e x p l a i n e d by s u p p r e s s i o n o f i c e l e n s i n g b e c a u s e of g r e a t e r o v e r b u r d e n p r e s s u r e under t h i c k e r i c e . D e b r i s l a y e r s c o u l d be s t r i p p e d d u r i n g s u r g i n g , but t h e Backe s t i l l h as e x p o s u r e s o f b a s a l d e b r i s a c r o s s t h e t e r m i n u s . B a s a l m e l t i n g i n t h e c e n t r a l z o n e , p o s s i b l y f r o m h e a t f l u x i n t h e b a s a l w a t e r s y s t e m , a l s o may s t r i p d e b r i s l a y e r s . A l t h o u g h t h e r e a r e s e v e r a l p o s s i b l e e x p l a n a t i o n s , t h e c a u s e o f t h e l a c k of c e n t r a l i c e d e b r i s l a y e r s r e m a i n s a m y s t e r y , p o s s i b l y u n t i l t h e n e x t s u r g e . The r e g u l a r i t y and a r e a l e x t e n t of d e b r i s l a y e r s i n Backe and T r a p r i d g e s u g g e s t an a c c r e t i o n mechanism t h a t i s i n d e p e n d e n t o f v a r i a t i o n s i n t h e bed p r o f i l e . I c e s e g r e g a t i o n i s a r e a s o n a b l e p r o c e s s t o e x p l a i n t h e u n i f o r m i t y o f t h e b a s a l l a y e r s . I n c o r p o r a t i o n o f 20 t o 50 l a y e r s i n 300 y e a r s i m p l i e s an a c t i v e s u b g l a c i a l s y s t e m i n w h i c h v a r i a b i l i t y o f w a t e r s u p p l y and b a s a l h e a t f l u x w i l l i n f l u e n c e t h e r a t e s o f b a s a l f r e e z i n g and t h e i n c o r p o r a t i o n o f d e b r i s . The v a r i a t i o n s i n i s o t o p i c c o m p o s i t i o n and s h i f t s i n heavy i s o t o p e r e l a t i o n s h i p s s u p p o r t v a r i a b l e t h e r m a l and h y d r o l o g i c a l c o n d i t i o n s a t s u r g i n g g l a c i e r b e d s . S e v e r a l mechanisms o f d e b r i s e n t r a i n m e n t w i t h t h e o b s e r v e d i s o t o p i c c h a r a c t e r i s t i c s a r e p o s s i b l e . The g r e a t e s t i s o t o p i c 101 i n f l u e n c e w i l l be c h a n g e s i n t h e c o m p o s i t i o n o f t h e b a s a l r e s e r v o i r . F r a c t i o n a t i o n e f f e c t s c a u s e d by i c e s e g r e g a t i o n o r i n t r u s i o n p r o c e s s e s , a s u n d e r s t o o d a t p r e s e n t , a r e n o t s i g n i f i c a n t enough t o a c c o u n t f o r t h e l a r g e i s o t o p i c v a r i a t i o n s . The f o l l o w i n g c o n c e p t u a l m o d e l s a r e s u g g e s t e d : 1. D e b r i s i s i n c o r p o r a t e d d u r i n g p e r i o d s o f low water s u p p l y . T h e s e p e r i o d s would c o r r e s p o n d t o w i n t e r f l o w s when t h e w a t e r i s d e p l e t e d i n hea v y i s o t o p e s . As t h e w a t e r s u p p l y i n c r e a s e s i n s p r i n g t h e water becomes h e a v i e r t h u s t h e i n c o r p o r a t e d i c e becomes h e a v i e r . The i s o t o p i c s t r a t i g r a p h y i s d e p e n d e n t upon t h e t i m e c h a n g e s i n i s o t o p i c c o m p o s i t i o n o f t h e b a s a l w a ter s u p p l y . 2. D e b r i s i s i n c o r p o r a t e d d u r i n g p e r i o d s o f advancement of t h e f r e e z i n g p l a n e c a u s e d by low w a t e r s u p p l y a n d / o r i n t r u s i o n o f i c e . W i n t e r b a s a l w ater f l o w i s l o w e r and n o t m i x e d as w e l l a s summer f l o w s c a u s i n g l e s s f r a c t i o n a t i o n . A d e b r i s l a y e r i s i n c o r p o r a t e d between h i g h l y f r a c t i o n a t e d summer f l o w and l e s s f r a c t i o n a t e d w i n t e r f l o w . In a d d i t i o n , t h e i s o t o p i c s t r a t i g r a p h y w i l l be a f f e c t e d by t h e c o m p o s i t i o n o f t h e i n p u t w a t e r . 3. A p r o c e s s s u c h a s s e c o n d a r y h e a v i n g i n c o r p o r a t e s d e b r i s . The f r e e z i n g p r o c e s s may i n h e r e n t l y c a u s e i s o t o p i c v a r i a t i o n s . As an i c e l e n s grows, t h e e f f e c t s o f u l t r a f i l t r a t i o n i n c r e a s e t h e c o n c e n t r a t i o n of heavy i s o t o p e s i n t h e water f i l m i n t h e f r o z e n 1 02 f r i n g e , p a r t i c u l a r l y n e a r t h e i c e l e n s where t h e f i l m i s t h i n n e s t . A f t e r a d e b r i s l a y e r i s i n c o r p o r a t e d , t h e new i c e l e n s i s i s o t o p i c a l l y l i g h t e r and t h e c y c l e r e p e a t s . A d d i t i o n a l v a r i a t i o n s i n t h e i s o t o p i c s t r a t i g r a p h y may be c a u s e d by i n p u t v a r i a t i o n s . T h e s e t h r e e mechanisms c a n c a u s e t h e f r e q u e n t l y o b s e r v e d i s o t o p i c t r e n d of i n c r e a s i n g 5 between d e b r i s l a y e r s . S e a s o n a l water s u p p l y v a r i a t i o n s c a n c a u s e t h e i s o t o p i c s e q u e n c e t o v a r y f r o m t h e i n c r e a s i n g t r e n d as o b s e r v e d i n some c a s e s . C h a p t e r 5 CONCLUSIONS The complex s u b g l a c i a l e n v i r o n m e n t i s a p u z z l e t h a t c a n be s o l v e d by a b l e n d i n g o f f i e l d o b s e r v a t i o n s , p r o c e s s m o d e l l i n g and l a b o r a t o r y s i m u l a t i o n . In t h i s s t u d y , b a s a l a c c r e t i o n p r o c e s s e s and b u l k i c e e v o l u t i o n p r o c e s s e s have been i n t e r p r e t e d t h r o u g h t h e medium of i s o t o p i c a n a l y s e s . The i s o t o p i c r e s u l t s , s u p p l e m e n t e d by s e d i m e n t and w a t e r q u a l i t y a n a l y s e s , p r o v i d e d t o o l s t o u n r a v e l t h e mechanisms of b a s a l i c e and d e b r i s i n c o r p o r a t i o n i n two s u r g i n g g l a c i e r s . I have h y p o t h e s i z e d c o n d i t i o n s t h a t c an c a u s e t h e e x t e n s i v e d e b r i s l a y e r s t h a t a r e o b s e r v e d i n many s u b p o l a r g l a c i e r s . T hese h y p o t h e s e s c a n a l s o be e x t e n d e d t o p r o p e r t i e s of t e m p e r a t e and p o l a r g l a c i e r s . The r e s u l t s i n d i c a t e t h a t a g l a c i e r i s a f i l t e r t h a t p r e f e r e n t i a l l y r e l e a s e s t h e l i g h t e r i s o t o p i c s p e c i e s o f w a t e r . E v a p o r a t i o n / s u b l i m a t i o n f r a c t i o n a t i o n s and m e l t / f r e e z e f r a c t i o n a t i o n s c a u s e t h e heavy i s o t o p e s t o be c o n c e n t r a t e d i n b u l k and b a s a l i c e . I have i s o t o p i c a l l y c h a r a c t e r i z e d b u l k and b a s a l i c e on T r a p r i d g e and Backe G l a c i e r s . F r a c t i o n a t i o n s d u r i n g e v o l u t i o n o f p r e c i p i t a t i o n t o b u l k i c e c a u s e e n r i c h m e n t i n t h e i c e . The o b s e r v e d h e a v y i s o t o p e s h i f t s and s l o p e s a r e s i m i l a r t o r e s u l t s from e v o l u t i o n o f f r e s h snow (Moser and S t i c h l e r 1975), a l t h o u g h t h e g l a c i e r samples have p r o b a b l y d e v e l o p e d f r o m v a r i a b l e i s o t o p i c s o u r c e s of p r e c i p i t a t i o n and m e l t , u n l i k e t h e snow e v o l u t i o n s t u d i e s . F o r t h i s r e a s o n , b u l k i c e 5 D / 6 0 1 8 s l o p e s c h a r a c t e r i z e a sample s e t n o t a f r a c t i o n a t i o n p r o c e s s . Snow 103 104 f r a c t i o n a t i o n p r o c e s s e s o f p e r c o l a t i o n and e v a p o r a t i o n / s u b l i m a t i o n have a major r o l e i n i c e f o r m a t i o n on T r a p r i d g e and Backe G l a c i e r s . G l a c i e r s t h a t have s i m i l a r c l i m a t i c c o n d i t i o n s w i l l a l s o have b u l k i c e w i t h c h a r a c t e r i s t i c s l o p e s t h a t a r e s h i f t e d f r o m t h e m e t e o r i c v a l u e o f 8. One e x p l a n a t i o n f o r t h e c h a r a c t e r i s t i c s l o p e s o f b u l k i c e may be t h e i n s u l a t i o n o f l i g h t e r w i n t e r p r e c i p i t a t i o n from upper snow l a y e r i n f l u e n c e s s u c h a s e v a p o r a t i o n and a b l a t i o n p r o c e s s e s . E a c h snow l a y e r i s s h i f t e d a l o n g a s l o p e t h a t i s c h a r a c t e r i s t i c o f a snow e v o l u t i o n p r o c e s s . H e a v i e r l a y e r s a r e s h i f t e d t o a g r e a t e r d e g r e e t h a n l i g h t e r snow and t h e o b s e r v e d s l o p e s a r e l e s s t h a n 8. The heavy i s o t o p e r e l a t i o n s h i p o f b a s a l i c e i s s i m i l a r t o t h e b u l k i c e b e c a u s e t h e s o u r c e o f water c a n a l s o be v a r i a b l e . A l t h o u g h t h e s l o p e s a r e l o w e r t h a n t h e b u l k i c e v a l u e s , t h e y a r e h i g h e r t h a n e q u i l i b r i u m o r n o n - e q u i l i b r i u m model s l o p e s of i c e / w a t e r f r a c t i o n a t i o n p r o c e s s e s . I p r o p o s e t h a t f r e e z i n g and c i r c u l a t i o n p r o c e s s e s i n s e d i m e n t s u b s t r a t e s i m p r i n t i s o t o p i c e f f e c t s on t h e s i m p l e f r e e z i n g p r o c e s s . A d s o r b e d w a t e r f i l m s i n a f r o z e n f r i n g e may c a u s e s u r f a c e f o r c e s t o i s o t o p i c a l l y i n f l u e n c e w a t e r f l o w t o t h e f r e e z i n g f r o n t . M i x i n g p r o c e s s e s , and v a r i a t i o n s i n water s u p p l y and i s o t o p i c c o m p o s i t i o n r e s u l t i n g f r o m h y d r o l o g i c a l and t h e r m a l c y c l e s a t t h e bed, must be major i n f l u e n c e s on t h e b a s a l i s o t o p i c s t r a t i g r a p h y . The r e s u l t s of t h e d e n s e l y s a m p l e d i s o t o p i c s t r a t i g r a p h y p r o v i d e c h a r a c t e r i s t i c s t h a t must be a c c o u n t e d f o r by any b a s a l a c c r e t i o n m o d e l . The f r e q u e n t e n r i c h m e n t s between d e b r i s l a y e r s s u g g e s t t h a t an o v e r r i d i n g p r o c e s s l e a d s t o e n r i c h e d w a t e r as a 1 05 d e b r i s l a y e r i s i n c o r p o r a t e d , t h e n d e p l e t i o n a s t h e n e x t i c e l a y e r i s i n c o r p o r a t e d . I have h y p o t h e s i z e d s e v e r a l p r o c e s s e s t h a t c a n c a u s e t h i s s e q u e n c e . A s e a s o n a l a c c r e t i o n may o c c u r i n w h i c h a d e b r i s l a y e r i s i n c o r p o r a t e d d u r i n g w i n t e r s when t h e f r e e z i n g p l a n e a d v a n c e s i n t o t h e s u b s t r a t e b e c a u s e t h e r e i s l e s s w a ter a v a i l a b l e f o r i c e s e g r e g a t i o n . The i n p u t w ater i s i n i t i a l l y l i g h t a t t h e b e g i n n i n g of t h i s a c c r e t i o n c y c l e , and e n r i c h e d l a t e r d u r i n g t h e m e l t s e a s o n due t o m i x i n g of b a s a l m e l t w i t h i s o t o p i c a l l y h e a v i e r p r e c i p i t a t i o n and s u r f a c e m e l t . F r e e z i n g r a t e v a r i a t i o n s may c a u s e v a r i a b l e i s o t o p i c f r a c t i o n a t i o n . I f summer w a t e r f l o w c a u s e s r e d u c e d r a t e s o f i c e s e g r e g a t i o n w i t h good m i x i n g i n t h e b a s a l r e s e r v o i r , f r a c t i o n a t i o n w i l l be c o m p l e t e and t h e i c e w i l l be h e a v i e r t h a n d u r i n g f a s t e r f r e e z i n g a t t h e b e g i n n i n g of t h e m e l t s e a s o n . D u r i n g e n t r a i n m e n t o f d e b r i s , t h e f r e e z i n g r a t e o f water s h i f t s from slow w i t h good m i x i n g t o f a s t w i t h p o o r m i x i n g d u r i n g t h e l o w e r w i n t e r f l o w s . F i n a l l y , a s e c o n d a r y h e a v i n g p r o c e s s may c a u s e r e t a r d a t i o n of heavy i s o t o p e f l o w t o an i c e l e n s . The i c e l e n s w i l l be i n i t i a l l y l i g h t a nd become h e a v i e r a s t h e heavy i s o t o p i c c o m p o s i t i o n i n t h e f r o z e n f r i n g e i n c r e a s e s . A d e b r i s l a y e r w i l l be e n r i c h e d i n heavy i s o t o p e s . A l l o f t h e s e p r o p o s e d mechanisms can be a f f e c t e d by v a r i a t i o n s d u r i n g d i f f e r e n t s e a s o n s t h e r e b y c a u s i n g t h e i s o t o p i c t r e n d between d e b r i s l a y e r s n o t t o show a s t r o n g i n c r e a s e i n 6. T h e r m a l e f f e c t s o f s u b g l a c i a l w ater f l o w d e t e r m i n e t h e f e a s i b i l i t y o f an a n n u a l c y c l e o f b a s a l e n t r a i n m e n t o f d e b r i s . I e n c o u n t e r e d p r o b l e m s i n j u s t i f y i n g t h i c k i c e l a y e r s from t h e t h e r m a l g r a d i e n t s t h a t a r e o b s e r v e d on T r a p r i d g e G l a c i e r . T h e r m a l 106 g r a d i e n t s a r e h i g h e r j u s t a f t e r a s u r g e due t o t h i n n i n g of t h e g l a c i e r . The c r a c k e d s u r f a c e a l s o a l l o w s l a r g e amounts o f s u r f a c e w a ter t o r e a c h t h e bed. The t h i c k i c e l a y e r s may be i n c o r p o r a t e d j u s t a f t e r a s u r g e . A s e c o n d a c c r e t i o n mechanism c o u l d be t h e s e c o n d a r y h e a v i n g p r o c e s s w h i c h may i n c o r p o r a t e t h i c k i c e l a y e r s . 5.1 THE FUTURE Two m a j o r t h r u s t s c a n be made f r o m t h e b a s i s of t h i s s t u d y . In g l a c i a l s t u d i e s , t h e p h y s i c s and c h e m i s t r y of water movement i n f r o z e n s o i l s and t h e e x t e n s i v e r e s e a r c h i n p e r m a f r o s t s h o u l d be i n c r e a s i n g l y a p p l i e d t o s u b g l a c i a l p r o c e s s e s . I n t h e s t u d y of water movement i n f r o z e n s o i l s , i s o t o p i c methods may r e v e a l t h e p h y s i c s of f l o w of w a t e r and r e g e l a t i n g i c e t o a f r e e z i n g p l a n e . The r e s u l t s o f t h i s s t u d y s u g g e s t t h a t i c e s e g r e g a t i o n o c c u r s a t t h e base of s u r g i n g g l a c i e r s . G l a c i e r s a r e a p e r m a f r o s t phenomena w h i c h o c c u r above t h e g r o u n d . S u b g l a c i a l l y , p r o c e s s e s s i m i l a r t o s u b - s u r f a c e p e r m a f r o s t z o n e s c a n o c c u r . The i m p o r t a n c e of t h e s u b s t r a t e m a t e r i a l i s a p p a r e n t . A s e d i m e n t s u b s t r a t e w h i c h i s above f r e e z i n g t e m p e r a t u r e p e r m i t s movement o f water t o a f r e e z i n g p l a n e . Water c a n a l s o move t h r o u g h f r o z e n s o i l s and t h e a d d i t i o n o f i c e and s e d i m e n t a t t h e base of a g l a c i e r i s a d i r e c t c o n s e q u e n c e o f t h i s s u b g l a c i a l w a t e r f l o w . S u b g l a c i a l a c c r e t i o n i s n o t l i m i t e d t o s u r g i n g g l a c i e r s or s u b p o l a r g l a c i e r s . T e m p e r a t e g l a c i e r s c a n i n c o r p o r a t e i c e and d e b r i s i n r e g i o n s where t e m p e r a t u r e c o n d i t i o n s ( h e a t r e m o v a l v e r s u s h e a t p r o d u c t i o n ) c a u s e water f l o w t o i c e o r advancement o f a f r e e z i n g p l a n e i n t o t h e s u b s t r a t e . A c c r e t i o n p r o c e s s e s s i m i l a r t o t h o s e 107 s u g g e s t e d i n t h i s t h e s i s c a n be r e s p o n s i b l e f o r t h e movement of l a r g e amounts o f d e b r i s f r o m g l a c i a t e d l a n d s c a p e s , p a r t i c u l a r l y on t h e s c a l e o f c o n t i n e n t a l g l a c i a t i o n . To u n d e r s t a n d b a s a l a c c r e t i o n p r o c e s s e s , t h e mechanism of w a t e r movement t o b a s a l i c e n e e d s t o be u n d e r s t o o d . P e r m a f r o s t s t u d i e s o f w ater f l o w i n f r o z e n s o i l s a r e c o n c e n t r a t i n g on t h e i m p o r t a n c e of t h e a d s o r b e d w a t e r l a y e r . T h i s l a y e r i s v e r y t h i n and s u r f a c e f o r c e s o f i c e and s o i l g r a i n s a r e a c t i v e i n t h e water f l o w . The s u r f a c e f o r c e s on w a t e r m o l e c u l e s may c a u s e i s o t o p i c u l t r a f i l t r a t i o n d u r i n g f l o w t h r o u g h s m a l l w ater c h a n n e l s i n a f r o z e n f r i n g e . F r a c t i o n a t i o n d u r i n g f l o w c a n p r o v i d e a measure o f t h e i c e and w ater movement. I f i c e l e n s e s a r e grown d u r i n g w a t e r f l o w t h r o u g h f r o z e n s o i l o r p e r m e a b l e membranes t h a t s i m u l a t e f r o z e n s o i l , i s o t o p i c a n a l y s e s o f t h e i c e l e n s e s c a n r e v e a l t h e f r a c t i o n a t i o n t h a t o c c u r s . I f t h e r e i s s i g n i f i c a n t i s o t o p i c v a r i a t i o n i n s p i t e o f a c o n s t a n t i s o t o p i c r e s e r v o i r , t h e d i f f e r e n t i c e s e g r e g a t i o n h y p o t h e s e s must be a b l e t o a c c o u n t f o r t h e v a r i a t i o n s . I f t h e r e i s no v a r i a t i o n , t h e n an i s o t o p i c t e c h n i q u e w i l l not n e c e s s a r i l y r e v e a l t h e h e a v i n g mechanism. A c o n s t a n t i s o t o p i c r e s u l t would s u p p o r t e x p l a n a t i o n s o f r e s e r v o i r m i x i n g o r f r e e z i n g r a t e v a r i a t i o n s f o r t h e o b s e r v e d b a s a l i c e i s o t o p i c r e s u l t s . T h e s e p a r a m e t e r s c a n be v a r i e d i n l a b o r a t o r y s i m u l a t i o n s o f b a s a l f r e e z i n g . I n t h e f u t u r e , i t i s i m p o r t a n t t h a t g l a c i o l o g i s t s examine b a s a l i c e and w a t e r , and s u b s t r a t e i n t e r a c t i o n s w i t h c o n s i d e r a t i o n s o f t h e c o n c e p t s o f p e r m a f r o s t . The g l a c i a l s y s t e m i s a d i f f e r e n t i a l l y f l o w i n g p e r m a f r o s t o v e r a bed of p e r m a f r o s t 108 o r n o n - p e r m a f r o s t w h i c h may a l s o be f l o w i n g . REFERENCES AHERN, T.K. 1975. An 0 1 8 / 0 1 6 s t u d y o f water f l o w i n n a t u r a l snow. M.Sc. 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 , V a n c o u v e r , Canada, 164 p. AHERN, T.K. 1980. The d e v e l o p m e n t o f a c o m p l e t e l y a u t o m a t e d oxygen i s o t o p e mass s p e c t r o m e t e r . Ph.D. T h e s i s , U n i v e r s i t y of B r i t i s h C o l u m b i a , V a n c o u v e r , Canada, 181 p. AMBACH, W., EISNER, H., ELSASSER, M., LOSCHHORN, U., MOSER, H., RAUERT, W., and STICHLER, W. 1976. D e u t e r i u m , t r i t i u m and g r o s s - b e t a - a c t i v i t y i n v e s t i g a t i o n s on A l p i n e g l a c i e r s ( O e t z a l A l p s ) . J o u r n a l o f G l a c i o l o g y , 17, pp. 383-400. ARNASON, B. 1969a. E q u i l i b r i u m c o n s t a n t f o r t h e f r a c t i o n a t i o n o f d e u t e r i u m between i c e and w a t e r . J o u r n a l of P h y s i c a l C h e m i s t r y , 73, pp. 3491-3494. , 1969b. The exchange of h y d r o g e n i s o t o p e s between i c e and water i n t e m p e r a t e g l a c i e r s . E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 6, pp. 423-430. , 1970. Exchange o f d e u t e r i u m between i c e and water i n g l a c i o l o g i c a l s t u d i e s i n I c e l a n d . In I s o t o p e h y d r o l o g y 1970. IAEA, V i e n n a , pp. 59-71. , 1981. I c e and snow h y d r o l o g y . In S t a b l e i s o t o p e h y d r o l o g y . Edited by J.R. G a t and R. G o n f i a n t i n i . IAEA T e c h n i c a l R e p o r t S e r i e s , 210, V i e n n a , pp. 143-176. ARNASON, B., BUASON, TH., MARTINEC, J . , and THEODORSSON, P. 1973. Movement of water t h r o u g h snowpack t r a c e d by d e u t e r i u m and t r i t i u m . In The r o l e o f i c e and snow i n h y d r o l o g y . P r o c e e d i n g s o f B a n f f Symposium 1972. UNESCO-WMO-IASH, pp. 299-312. BEHRENS, H.,MOSER, H., RAUERT, W., STICHLER, W., and KIRCHLECHNER, P., 1979. M o d e l s f o r t h e r u n - o f f from a g l a c i a t e d c a t c h m e n t a r e a u s i n g measurements of e n v i r o n m e n t a l i s o t o p e c o n t e n t s . In I s o t o p e H y d r o l o g y 1978. IAEA, V i e n n a , pp. 829-846. BINDSCHADLER, R.W., HARRISON, W.D., RAYMOND, C.F., and GANTET, C. 1976. T h e r m a l r e g i m e o f a s u r g e - t y p e g l a c i e r . J o u r n a l of G l a c i o l o g y , 16, pp. 251-259. BISHOP, B.C. 1957. S h e a r m o r a i n e s i n t h e Th.ule a r e a , n o r t h w e s t G r e e n l a n d . U.S. Snow I c e and P e r m a f r o s t R e s e a r c h E s t a b l i s h m e n t . R e s e a r c h R e p o r t , 17. BOULTON, G.S. 1970. On t h e o r i g i n and t r a n s p o r t of e n g l a c i a l d e b r i s i n S v a l b a r d g l a c i e r s . J o u r n a l of G l a c i o l o g y , 9, pp. 109 110 213-229. , 1972. The r o l e o f t h e r m a l r e g i m e i n g l a c i a l s e d i m e n t a t i o n . I n s t i t u t e o f B r i t i s h G e o g r a p h e r s S p e c i a l P u b l i c a t i o n , 4 , pp. 1-19. , 1979. B o u l d e r s h a p e s and g r a i n - s i z e d i s t r i b u t i o n s o f d e b r i s a s i n d i c a t o r s of t r a n s p o r t p a t h s t h r o u g h a g l a c i e r and t i l l g e n e s i s . S e d i m e n t o l o g y , 25, pp. 773-779. , 1983. D e b r i s and i s o t o p i c s e q u e n c e s i n b a s a l l a y e r s o f p o l a r i c e s h e e t s . In The c l i m a t i c r e c o r d i n p o l a r i c e s h e e t s . Edited by G. de Q. R o b i n , C a mbridge U n i v e r s i t y P r e s s , C a m b r i d g e , pp. 83-89. BREWER, T. 1972. A t w o - y e a r - m a s s - b a l a n c e s t u d y o f t h e R u s t y G l a c i e r 1968-1969. In I c e f i e l d Ranges R e s e a r c h P r o j e c t S c i e n t i f i c R e s u l t s , Volume 3. A r c t i c I n s t i t u t e of N o r t h A m e r i c a , M o n t r e a l , Canada, pp. 75-82. BUASON, TH. 1972. E q u a t i o n s of i s o t o p e f r a c t i o n a t i o n between i c e and w a t e r i n a m e l t i n g snow column w i t h c o n t i n u o u s r a i n and p e r c o l a t i o n . J o u r n a l of G l a c i o l o g y , 12, pp. 387-405. CLARKE, G.K.C. 1976. T h e r m a l r e g u l a t i o n o f g l a c i e r s u r g i n g . J o u r n a l o f G l a c i o l o g y , - 16, pp. 231-250. CLARKE, G . K . C , COLLINS S.G., and THOMPSON, D.E. 1984. Fl o w , t h e r m a l s t r u c t u r e , and s u b g l a c i a l c o n d i t i o n s o f a s u r g e - t y p e g l a c i e r . C a n a d i a n J o u r n a l o f E a r t h S c i e n c e s , 21, pp. 232-240. CLASSEN, D.F., and CLARKE, G.K.C. 1972. T h e r m a l d r i l l i n g and i c e - t e m p e r a t u r e measurements i n t h e R u s t y G l a c i e r . In I c e f i e l d Ranges R e s e a r c h P r o j e c t S c i e n t i f i c R e s u l t s , Volume 3. A r c t i c I n s t i t u t e of N o r t h A m e r i c a , M o n t r e a l , Canada, pp. 103-116. COLLINS, S.G. 1972. S u r v e y o f t h e R u s t y G l a c i e r a r e a , Yukon T e r r i t o r y , C anada. J o u r n a l o f G l a c i o l o g y , 11, pp. 235-253. COPLEN, T.B., and HANSHAW, B.B. 1973. U l t r a f i l t r a t i o n by a co m p a c t e d c l a y membrane-I. Oxygen and h y d r o g e n i s o t o p i c f r a c t i o n a t i o n . G e o c h i m i c a and C o s m o c h i m i c a A c t a , 37, pp. 2295-2310. CRAIG, H. 1961. I s o t o p i c v a r i a t i o n s i n m e t e o r i c w a t e r s . S c i e n c e , 133, pp. 1702-1703. CRAIG, H., and GORDON, L. 1965. I s o t o p i c c h a r a c t e r i s t i c s o f m a r i n e and c o n t i n e n t a l w a t e r v a p o u r . T r a n s a c t i o n s of t h e A m e r i c a n G e o p h y s i c a l U n i o n , 68, pp. 135-136. DANSGAARD, W. 1964. S t a b l e i s o t o p e s i n p r e c i p i t a t i o n . T e l l u s , 16, 111 pp. 436-468. F R I T Z , P., and FONTES, J . C h . 1980. Handbook o f E n v i r o n m e n t a l G e o c h e m i s t r y . 1, Amsterdam, 545 p. GAT, J.R. 1981. G r o u n d w a t e r . In S t a b l e i s o t o p e h y d r o l o g y . Edited by J.R. Gat and R. G o n f i a n t i n i . IAEA T e c h n i c a l R e p o r t S e r i e s , 210, V i e n n a , pp. 223-240. GAT, J.R., and GONFIANTINI, R. 1981. S t a b l e i s o t o p e h y d r o l o g y . IAEA T e c h n i c a l R e p o r t S e r i e s , 210, V i e n n a , 337 p. GAT, J.R., and TZUR, Y. 1967. M o d i f i c a t i o n o f t h e i s o t o p i c c o m p o s i t i o n of r a i n w a t e r by p r o c e s s e s w h i c h o c c u r b e f o r e g r o u n d w a t e r r e c h a r g e . In I s o t o p e s i n h y d r o l o g y . IAEA, V i e n n a , pp. 215-223. GOLDTHWAIT, R.P. 1951. D e v e l o p m e n t o f end m o r a i n e s i n e a s t - c e n t r a l B a f f i n I s l a n d . J o u r n a l of G e o l o g y , 59, pp. 567-577. GRAF, D.L., FRIEDMAN, I . , and MEENTS, W.F. 1965. The o r i g i n of s a l i n e f o r m a t i o n w a t e r s , I I . I s o t o p i c f r a c t i o n a t i o n by s h a l e m i c r o p o r e s y s t e m s . I l l i n o i s S t a t e G e o l o g i c a l S u r v e y C i r c u l a r , 393, 32 p. GOW, A . J . , EPSTEIN, S., and SHEEHY, ' W. 1979. On t h e o r i g i n o f s t r a t i f i e d d e b r i s i n i c e c o r e s f r o m t h e b o t t o m of t h e A n t a r c t i c i c e s h e e t . J o u r n a l o f G l a c i o l o g y , 23, pp. 185-192. HALLET, B., LORRAIN, R., and SOUCHEZ, R. 1978. The c o m p o s i t i o n o f b a s a l i c e f r o m a g l a c i e r s l i d i n g o v e r l i m e s t o n e s . G e o l o g i c a l S o c i e t y of A m e r i c a B u l l e t i n , 89, pp. 314-320. HARLAN, R.L. 1971. Water t r a n s p o r t i n f r o z e n and p a r t i a l l y f r o z e n p o r o u s m e d i a . In P r o c e e d i n g s of t h e E i g h t h C a n a d i a n H y d r o l o g i c a l Symposium, pp. 109-129. , 1973. A n a l y s i s of c o u p l e d h e a t - f l u i d t r a n s p o r t i n p a r t i a l l y f r o z e n s o i l . Water R e s o u r c e s R e s e a r c h , 9, pp. 1314-1323 . HOBBS, P.V. 1974. I c e p h y s i c s . C l a r e n d o n P r e s s , O x f o r d , E n g l a n d , 837 p. HOLDEN, J . T . 1984. A p p r o x i m a t e s o l u t i o n s f o r M i l l e r ' s t h e o r y of s e c o n d a r y h e a v e . In P e r m a f r o s t , P r o c e e d i n g s of t h e 4 t h I n t e r n a t i o n a l C o n f e r e n c e , 1983, N a t i o n a l Academy P r e s s , pp. 498-503. JARVIS, G.T., and CLARKE, G.K.C. 1975. The t h e r m a l r e g i m e o f T r a p r i d g e G l a c i e r and i t s r e l e v a n c e t o g l a c i e r s u r g i n g . J o u r n a l of G l a c i o l o g y , 14, pp.235-250. JONES, A.S. 1979. The f l o w o f i c e o v e r a t i l l bed. J o u r n a l of 1 12 G l a c i o l o g y , 22, pp. 393-395. JOUZEL, J . , and SOUCHEZ, R.A. 1982. M e l t i n g - r e f r e e z i n g a t t h e g l a c i e r s o l e and t h e i s o t o p i c c o m p o s i t i o n of t h e i c e . J o u r n a l o f G l a c i o l o g y , 28, pp. 35-42. KAMB, B.,RAYMOND, C.F., HARRISON, W.D., ENGELHARDT, K.A., ECHELMEYER, K.A., HUMPHREY, N., BRUGMAN, M.M., and PFEFFER, T. 1985. G l a c i e r s u r g e mechanism: 1982-1983 s u r g e of V a r i e g a t e d G l a c i e r , A l a s k a . S c i e n c e , 227, pp. 469-479. KHARAKA, Y.K., and BERRY, A.F. 1973. S i m u l t a n e o u s f l o w of wa t e r and s o l u t e s t h r o u g h g e o l o g i c a l membranes-I. E x p e r i m e n t a l i n v e s t i g a t i o n . G e o c h i m i c a and C o s m o c h i m i c a A c t a , 37, pp. 2577-2603. KIRSHENBAUM, I . 1951. P h y s i c a l p r o p e r t i e s and a n a l y s i s o f heavy w a t e r , N a t i o n a l N u c l e a r E n e r g y S e r v i c e , D i v i s i o n I I I , 4A, M c G r a w - H i l l . LAWRENCE,J.R., and TAYLOR, H.P. 1972. Hy d r o g e n and oxygen i s o t o p e s y s t e m a t i c s i n w e a t h e r i n g p r o f i l e s . G e o c h i m i c a and C o s m o c h i m i c a A c t a , 36, pp. 1377-1393. LAWSON, D.E., and KULLA, J.B. 1978. An oxygen i s o t o p e i n v e s t i g a t i o n of t h e o r i g i n of t h e b a s a l zone of t h e Mata n u s k a G l a c i e r , A l a s k a . J o u r n a l o f G e o l o g y , 86, pp. 673-685. LORRAIN, R.D., and DEMEUR, P. 1985. I s o t o p i c e v i d e n c e f o r r e l i c P l e i s t o c e n e g l a c i e r i c e on V i c t o r i a I s l a n d , C a n a d i a n A r c t i c A r c h i p e l a g o . A r c t i c and A l p i n e R e s e a r c h , 17, pp. 89-98. MACKAY, J.R. 1971. The o r i g i n of m a s s i v e i c y beds i n p e r m a f r o s t , W e s t e r n A r c t i c C o a s t , Canada. C a n a d i a n J o u r n a l o f E a r t h S c i e n c e s , 8, pp. 397-422. , 1973. P r o b l e m s i n t h e o r i g i n o f m a s s i v e i c y beds, W e s t e r n A r c t i c , Canada. In P e r m a f r o s t , The N o r t h A m e r i c a n C o n t r i b u t i o n t o t h e Second I n t e r n a t i o n a l C o n f e r e n c e . W a s h i n g t o n , D.C. N a t i o n a l Academy of S c i e n c e s , pp. 185-192. MAJOUBE, M. 1971. F r a c t i o n n e m e n t en oxygene 18 e t en d e u t e r i u m e n t r e l ' e a u e t sa v a p e u r . J o u r n a l de c h i m i e p h y s i q u e , 10, pp. 1423-1436. MARTINEC, J . , MOSER, H., DE QUERVAIN, M.R., RAUERT, W., and STICHLER, W. 1975. A s s e s s m e n t o f p r o c e s s e s i n t h e snowpack by p a r a l l e l d e u t e r i u m , t r i t i u m and oxygen-18 s a m p l i n g . In I s o t o p e s and I m p u r i t i e s i n Snow and I c e , P r o c e e d i n g s of G r e n o b l e Symposium, 1975. IASH P u b l i c a t i o n 118, pp. 220-231. MEIER, M.F., and POST, A.S. 1969. What a r e g l a c i e r s u r g e s ? C a n a d i a n J o u r n a l o f E a r t h S c i e n c e s , 6, pp. 807-817. 113 MERLIVAT, L., a n d COANTIC, M. 1975. S t u d y of mass t r a n s f e r a t t h e a i r - w a t e r i n t e r f a c e by an i s o t o p i c method, J o u r n a l o f G e o p h y s i c a l R e s e a r c h , 80, pp. 3455-3464. MICHEL, F.A. 1982. I s o t o p e i n v e s t i g a t i o n s o f p e r m a f r o s t w a t e r s i n N o r t h e r n Canada. Ph.D. d i s s e r t a t i o n , U n i v e r s i t y of W a t e r l o o , O n t a r i o . 424 p. MICHEL, F.A., and FRITZ, P. 1981. L a b o r a t o r y and f i e l d s t u d i e s t o i n v e s t i g a t e i s o t o p e e f f e c t s o c c u r r i n g d u r i n g t h e f o r m a t i o n of p e r m a f r o s t - Phase I I I -. E a r t h P h y s i c s B r a n c h Open F i l e , 81/5, O t t a w a , Canada, 57 p. , 1982. S i g n i f i c a n c e of i s o t o p e v a r i a t i o n s i n p e r m a f r o s t water a t I l l i s a r v i k , N.W.T. In The Roger J . E . Brown M e m o r i a l Volume: P r o c e e d i n g s o f t h e F o u r t h C a n a d i a n P e r m a f r o s t C o n f e r e n c e , C a l g a r y , A l b e r t a . O t tawa, N a t i o n a l R e s e a r c h C o u n c i l o f Canada, A s s o c i a t e Committee o f G e o t e c h n i c a l R e s e a r c c h , pp. 173-181. MILLER, R.D. 1980. F r e e z i n g phenomena i n s o i l s . In A p p l i c a t i o n s of s o i l p h y s i c s . Edited by D. H i l l e l , A cademic P r e s s , New Yor k , pp. 254-299. MOSER, H., and STICHLER, W. 1970. D e u t e r i u m measurements on snow samples f r o m t h e A l p s . In I s o t o p e h y d r o l o g y . IAEA, V i e n n a , pp. 43-57. MOSER, H., and STICHLER, W. 1975. D e u t e r i u m and oxygen-18 c o n t e n t s a s i n d e x o f t h e p r o p e r t i e s o f snow b l a n k e t s . In Snow M e c h a n i c s , P r o c e e d i n g s o f t h e G r i n d e l w a l d Symposium, A p r i l , 1974. IASH P u b l i c a t i o n , 114, pp. 122-135. O'NEILL, J.R. 1968. Hyd r o g e n and oxygen i s o t o p e f r a c t i o n a t i o n between i c e and w a t e r . J o u r n a l of P h y s i c a l C h e m i s t r y , 72, pp. 3683-3684. O'NEILL, K. 1983. The p h y s i c s o f m a t h e m a t i c a l f r o s t heave m o d e l s : A r e v i e w . C o l d R e g i o n s S c i e n c e and T e c h n o l o g y , 6, pp. 275-291. O'NEILL, K., and MILLER, R.D. 1982. N u m e r i c a l s o l u t i o n s f o r a r i g i d - i c e model o f s e c o n d a r y h e a v e . U.S. Army C o l d R e g i o n s R e s e a r c h and E n g i n e e r i n g L a b o r a t o r y R e p o r t , 82-13, 11 p. OUTCALT, S . I . 1980. A s i m p l e e n e r g y b a l a n c e model o f i c e s e g r e g a t i o n . C o l d R e g i o n s S c i e n c e and T e c h n o l o g y , 3, pp. 145-152. POSEY, J . C . and SMITH, H.A. 1957. The e q u i l i b r i u m d i s t r i b u t i o n o f l i g h t and heavy w a t e r s i n a f r e e z i n g m i x t u r e . J o u r n a l o f A m e r i c a n C h e m i c a l S o c i e t y , 79, pp. 555-557. ROBIN, G. DE Q., and WEERTMAN, J . 1973. C y c l i c s u r g i n g of 1 14 g l a c i e r s . J o u r n a l o f G l a c i o l o g y , 12, pp. 3-18. SAVIN, S.M., and EPSTEIN, S. 1970. The oxygen and h y d r o g e n i s o t o p e g e o c h e m i s t r y o f c l a y m i n e r a l s . G e o c h i m i c a and C o s m o c h i m i c a A c t a , 34, pp. 25-42. SOUCHEZ, R.A., and DE GROOTE, J.M. 1985. 5 D - 6 0 1 8 r e l a t i o n s h i p s i n i c e f ormed by s u b g l a c i a l f r e e z i n g : p a l e o c l i m a t i c i m p l i c a t i o n s . J o u r n a l o f G l a c i o l o g y , 31, pp. 229-232. SOUCHEZ, R.A., and JOUZEL, J . 1984. On t h e i s o t o p i c c o m p o s i t i o n i n 6D and S O 1 8 of w a t e r and i c e d u r i n g f r e e z i n g . J o u r n a l of G l a c i o l o g y , 30, pp. 369-372. SOUCHEZ, R.A., and LORRAIN, R.D. 1975. C h e m i c a l s o r t i n g a t t h e bas e o f an a l p i n e g l a c i e r . J o u r n a l o f G l a c i o l o g y , 14, pp. 261-265. , 1978. O r i g i n o f t h e b a s a l i c e l a y e r f r o m A l p i n e g l a c i e r s i n d i c a t e d by i t s c h e m i s t r y . J o u r n a l o f G l a c i o l o g y , 20, pp. 319-328. TAKAGI, S. 1980. Summary o f t h e a d s o r p t i o n f o r c e t h e o r y of f r o s t h e a v i n g . C o l d R e g i o n s S c i e n c e and T e c h n o l o g y , 3, pp. 57-81. WADDINGTON, E.D. 1981. A c c u r a t e m o d e l l i n g o f g l a c i e r f l o w . Ph.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 , V a n c o u v e r , Canada, 460 p. WEAST, R.C. editor 1984. Handbook o f C h e m i s t r y and P h y s i c s . CRC P r e s s , C l e v e l a n d , O h i o . WEERTMAN, J . 1961. Mechanism f o r t h e f o r m a t i o n of i n n e r m o r a i n e s f o u n d n e a r t h e edge o f c o l d i c e c a p s and i c e s h e e t s . J o u r n a l of G l a c i o l o g y , 3, pp. 965-978. WESTON, R.E. 1955. Hydrogen i s o t o p e f r a c t i o n a t i o n between i c e and w a t e r . G e o c h i m i c a and C o s m o c h i m i c a A c t a , 8, pp. 281-284. WEST, K.E., and KROUSE, H.R. 1972. Abundance o f i s o t o p i c s p e c i e s o f w a t e r i n t h e S t . E l i a s M o u n t a i n s . In I c e f i e l d Ranges R e s e a r c h P r o j e c t S c i e n t i f i c R e s u l t s , Volume 3. A r c t i c I n s t i t u t e of N o r t h A m e r i c a , M o n t r e a l , pp. 117-130. WHAITE, P. 1982. An a u t o m a t e d sample l i n e f o r t h e p r e p a r a t i o n o f O 1 8 / 0 ' 6 i s o t o p e a n a l y s e s from water s a m p l e s . M.Sc. T h e s i s , U n i v e r s i t y of B r i t i s h C o l u m b i a , V a n c o u v e r , Canada, 165 p. WILLIAMS, P . J . 1968. P r o p e r t i e s and b e h a v i o u r of f r e e z i n g s o i l s , R e s e a r c h Paper 359, N a t i o n a l R e s e a r c h C o u n c i l of Canada, D i v i s i o n o f B u i l d i n g R e s e a r c h , O ttawa, O n t a r i o , 119 p. WILLIAMSON, J.H. 1968. L e a s t - s q u a r e s f i t t i n g o f a s t r a i g h t l i n e . C a n a d i a n J o u r n a l o f P h y s i c s , 46, pp. 1845-1847. 1 15 YORK, D. 1966. L e a s t s q u a r e s f i t t i n g o f a s t r a i g h t l i n e . C a n a d i a n J o u r n a l o f P h y s i c s , 4 4 , pp. 1079-1086. , 1967. The b e s t i s o c h r o n . E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 2, pp. 479-482. , 1969. L e a s t s q u a r e s f i t t i n g o f a s t r a i g h t l i n e w i t h c o r r e l a t e d e r r o r s . E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 5, pp. 320-324. YURTSEVER, Y., and GAT, J.R. 1981. A t m o s p h e r i c w a t e r s . In S t a b l e i s o t o p e h y d r o l o g y . Edited by J.R. Gat and R. G o n f i a n t i n i . IAEA T e c h n i c a l R e p o r t S e r i e s , 210, V i e n n a , pp. 103-142. ZIMMERMAN, U., EHHALT, D., and MUNNICH, K.O. 1967. S o i l w a ter movement and e v a p o t r a n s p i r a t i o n : change i n t h e i s o t o p i c c o m p o s i t i o n of t h e w a t e r . In I s o t o p e s i n h y d r o l o g y . IAEA, V i e n n a , pp. 567-585. APPENDIX 1. RESULTS OF ISOTOPIC ANALYSES. I have l i s t e d t h e r e s u l t s o f a l l of t h e i s o t o p i c a n a l y s e s f o r t h e i n t e r e s t of o t h e r r e s e a r c h e r s . The c o r e s a r e i d e n t i f i e d and t h e p o s i t i o n o f e a c h sample i n t h e c o r e s e q u e n c e . The 6 v a l u e w i t h t h e s t a n d a r d d e v i a t i o n of a n a l y s e s i s p r o v i d e d . Some o f t h e v a l u e s a r e a v e r a g e s o f more t h a n one r e a d i n g . The i c e t y p e ( S e c t i o n 3.1) i s i n c l u d e d i n a b b r e v i a t e d form. M i x e d i c e i s g i v e n a s a c o m b i n a t i o n o f t y p e s , i . e . DC d e s c r i b e s a sample w i t h d e b r i s and c l e a r i c e and B i l l d e s c r i b e s a sample w i t h B u b b l y I and B u b b l y II i c e . 1 16 1 1 7 T a b l e A l . l . I s o t o p i c r e s u l t s f o r TRST8. Sample P o s i t i o n I c e Type 5 0 1 8 a 6D a (cm) S094 98.0 C -26.98 0.07 -204.5 0.3 S095 94.0 BI -26.85 0.06 -207.4 0.2 S096 90.5 BI -26.54 0.07 -204.2 0.7 S097 87.5 BI -26.32 0.06 -204.8 0.5 S098 84.0 BI -26.48 0.04 -206.0 0.5 S099 80.0 BI -26.54 0.04 -205.6 0.6 S1 00 76.5 BI -26.69 0.02 -205.9 0.4 SI 0 1 73.5 BI -26.90 0.05 -204.6 0.3 S1 02 70.0 BI -27.57 0.05 -209.7 0.4 S103 66.0 BI -26.93 0.07 S1 04 62.0 BI -26.91 0.04 -206.0 0.3 S105 58.0 BI -26.60 0.04 S106 54.5 BI -26.58 0.03 -203.8 0.5 S107 51 .5 BI -26.40 0.04 S108 48.0 BI -26.14 0.11 -199.6 0.2 S109 44.0 BI -26.06 0.07 S1 1 0 40.5 BI -26.22 0.09 -202. 1 0.3 SI 1 1 37.5 BI -26.26 0.05 S1 1 2 34.5 CBI -26.04 0.04 -198.5 0.4 S1 1 3 31.5 BI -25.58 0.07 -195.6 0.4 S1 1 4 28.0 C -23.82 0.08 -184.5 0.2 S1 1 5 24.0 CBI -24.80 0.08 -190.9 0.3 SI 1 6 20.5 CBI -24.86 0.12 -192.2 0.1 S1 1 7 17.5 C -25.16 0.09 -192.4 0.5 SI 18 14.0 C -25.97 0.04 -197. 1 0.6 SI 19 10.0 C -25.98 0.09 S120 6.0 C -26.27 0.05 SI 21 2.0 C -26.19 0.08 118 T a b l e A1.2. I s o t o p i c r e s u l t s f o r TRB1. Sample P o s i t i o n (cm) I c e Type 60 1 8 a 6D 0 S1 22 1 .5 BI -26.82 0.05 -208.6 0.2 S123 4.5 BII -28.65 0.07 -222.0 0.7 S124 7.0 BII -27.05 0.06 S125 9.0 BII -26.32 0.02 S1 26 11.0 BII -25.95 0.08 -198.6 0.3 S1 27 13.0 BII -25.92 0.05 S1 28 15.0 BII -26.34 0.05 -201.5 0.2 S1 29 17.0 BII -26.79 0.03 S1 30 19.0 BII -26.75 0.04 S1 3 1 21 .0 BII -26.85 0.07 S1 32 23.0 BII -27.00 0.04 S133 25.0 BII -26.63 0.05 -202.3 0.6 S1 34 27.0 BII -25.96 0.09 -199.6 0.4 T a b l e A1.3. I s o t o p i c r e s u l t s f o r TRB2. Sample P o s i t i o n I c e Type 5 0 1 8 (cm) S151 44.5 BII -26.99 S1 52 41.5 BII -26.85 S153 39.0 BII -26.37 S1 54 37.0 DC -26.11 S155 35.0 CBI -25.49 S1 56 33.0 CBI -25.65 S1 57 31.0 D -26.08 S158 29.0 D -27.35 S1 59 26.5 DC -27.39 S1 60 23.5 C -27.00 S1 61 20.5 CBI -26.82 S1 62 17.5 CBI -26.29 S1 63 14.0 CBI -25.64 S164 10.0 DC -25.31 S1 65 6.0 DC -25.68 S1 66 2.0 BI -25.79 S1 67 48.0 D -26.04 L1 1 6 43.0 BII -26.44 L1 1 7 41.0 BII -26.20 L1 18 39.0 BII -26.26 L1 1 9 37.5 DC -25.64 L1 20 36.5 DBII -25.67 L1 21 35.5 C -25.40 L1 22 34.0 BI -25.89 L1 23 32.0 C -25.28 L1 24 31 .0 D -25.63 L1 25 28.5 CBI I -27.59 L1 26 26.0 CBI I -27.36 L1 27 24.0 C -26.90 L1 28 22.0 CBI -27. 18 L1 29 20.0 CBI -26.84 L1 30 18.0 CBI -26.51 L1 31 16.0 BI -26.39 L1 32 14.0 BI -26.26 L1 33 12.0 C -26.04 L1 34 10.0 C -25.79 o 5D a 0.05 0.06 0.08 0.05 0.08 0.08 0.07 0.08 -202.6 0.4 0.08 0.09 -208.3 0.3 0.05 0.04 0.03 0.10 -193.7 0.5 0.09 0.09 0.08 0.07 -202.5 0.5 0.08 0.06 -201 .3 0.7 0.06 -197. 1 0.3 0.12 -198.6 0.4 0.08 -195.5 0.3 0.08 -190.1 0.3 0.12 0.10 -187.3 0.2 0.11 0.11 -210.0 0.2 0.09 0.11 -209.5 0.5 0.10 0.02 -201 .3 0.4 0.08 0.05 -196.5 0.4 0.06 0.07 1 20 T a b l e A1.4. I s o t o p i c r e s u l t s f o r TRC1. Sample P o s i t i o n (cm) I c e Type 50 1 8 a 5D a S168 100.0 C -25.57 0.07 S169 97.0 C -24.99 0.08 S170 94.0 c -25.06 0.05 -194.7 0.2 S 1 7 1 91 .0 c -25.89 0.06 S1 72 88.0 c -25.06 0.08 S1 74 85.0 BI -25.84 0.05 -197.4 0.1 SI 75 82.0 BI -24.86 0.06 -192.0 0.1 S176 79.0 BI -25.26 0.07 S177 76.0 BI -25.67 0.07 -196.8 0.2 S178 73.0 BI -25.83 0.08 -196.8 0.4 S179 70.0 BI -25.97 0.04 -200.1 0.5 S180 67.0 BI -25.82 0.07 S181 64.0 BI -26.24 0.11 S182 61 .0 BI -25.55 0.05 S183 58.0 BI -25.47 0.07 -196.6 0.3 S184 55.0 BI -25.68 0.03 S185 52.0 BI -25.91 0.06 -199.4 0.3 S186 49.0 BI -25.74 0.06 S187 46.0 BI -25.64 0.07 S188 43.0 BI -25.99 0.06 -199.1 0.8 S189 40.0 D -25.13 0.05 -192.3 0.7 S1 90 37.0 BI -25.04 0.05 -192. 1 0.6 S 1 91 34.0 BI -24.99 0.08 -193.6 0.4 S1 92 31.0 BI -25.29 0.06 -195.6 0.4 S 1 93 27.5 BI -25.11 0.05 SI 94 24.5 D -24.69 0.06 -190.6 0.4 S195 23.5 D -24.42 0.04 -188.0 0.2 S196 22.5 DBI -24.90 0.06 -192.5 0.3 S197 19.0 D -25.28 0.06 -194.5 0.3 SI 98 16.0 D -25.13 0.06 S1 99 1 3.75 BI -24.89 0.08 -192.2 0.4 S200 12.0 BI -25.03 0.06 S201 9.5 BI -26.04 0.11 -197.2 0.3 S202 6.5 BI -25.29 0.04 -193.2 0.5 S203 3.5 BI -24.88 0.07 S204 2.1 D -24.79 0.04 -173.0 0.4 S212 0.1 BI -25.60 0.08 T a b l e A1.5. I s o t o p i c r e s u l t s f o r TRC2. Sample P o s i t i o n (cm) I c e Type 60 1 8 a 6D o S135 6.0 BII -26.89 0.06 S1 36 8.0 BII -26.55 0.06 S1 37 10.0 BII -26.61 0.08 S138 12.0 BII -27.24 0.09 S139 14.0 BII -26.46 0.03 S1 40 16.0 BII -26.92 0.04 SI 41 18.0 BII -27.24 0.10 S142 20.0 BII -27.65 0.08 S143 22.0 BII -28.38 0.06 S144 24.5 BII -28.23 0.07 -215.0 0.6 S1 45 27.5 BII -28.65 0.05 -218.5 0.2 S1 46 31 .0 BII -27.47 0.06 -209.4 0.4 S1 47 35.0 BII -28.07 0.08 S148 1 .5 BII -25.60 0.06 -198.5 0.7 S149 3.5 BII -25.56 0.04 -197.5 0.4 S150 4.5 BII -25.95 0.06 L099 52.0 BII -27.22 0.10 -205. 1 0.2 L1 00 50.0 BII -27.04 0.10 L1 01 48.0 BII -26.72 0.08 -203.3 0.4 L102 46.0 BII -26.50 0.08 L1 03 44.0 BII -26.51 0.04 -201.6 0.4 L1 04 42.0 BII -26.49 0.05 L1 05 40.0 BII -26.12 0.06 -199.2 0.2 L1 06 38.0 BII -25.91 0.05 L1 07 36.0 BII -26.04 0.09 -197.2 0.4 L1 08 34.0 BII -26.10 0.11 L1 09 30.0 BII -29.39 0.08 L1 1 0 28.0 BII -29.48 0.07 -222.0 0.4 L1 1 1 26.0 BII -28.88 0.11 -219.2 0.6 L1 1 2 24.0 BII -27.96 0.04 L1 1 3 22.0 BII -27.79 0.06 -210.9 0.3 L1 1 4 19.75 BII -27.57 0.09 L1 1 5 17.75 BI -27.25 0.06 -204.5 0.4 122 'able A l . 6. I s o t o p i c r e s u l t s f o r BA1. Sample P o s i t i o n I c e Type 6 0 1 8 a 5D o (cm) S003 14.0 D -24.61 0.09 S004 18.0 D -24.58 0.05 S005 22.0 D -26.14 0.07 S006 26.0 D -24.25 0.11 -183.9 0.6 S007 30.0 D -25.25 0.06 S008 34.0 D -24.87 0.04 -189.7 0.4 S009 38.0 D -25.23 0.09 -188.5 0.3 S010 42.0 D -25.17 0.11 S01 1 46.0 D -25.29 0.05 S01 2 50.0 D -24.62 0.07 -186.7 0.3 S01 3 54.0 D -24.59 0.05 SO 1 4 58.0 D -24.24 0.04 -186.0 0.3 S01 5 62.0 D -26.08 0.09 S016 66.0 D -26.30 0.08 SO 1 7 70.0 CBI -24. 16 0.11 S018 74.0 CBI -23.94 0.09 S01 9 78.0 CBI -24.06 0.06 S020 82.0 CBI -23.85 0.08 S021 86.0 CBI -24.35 0.03 S022 90.0 D -23.58 0.05 S023 94.0 D -23.61 0.06 S024 98.0 D -23.43 0.12 S025 101.5 CI -23.31 0.08 S026 104.5 CI -22.78 0.10 S027 107.0 DC -22.96 0.08 -180.5 0.7 S028 1 09.5 C -23.47 0.07 -183.3 0.3 S029 113.0 DC -23.45 0.06 S030 116.5 BI -23.83 0.06 S031 119.0 BI -23.49 0.06 S032 122.0 BI -23.90 0.10 S033 1 26.0 BI -23.40 0.07 S034 1 29.0 BI -23.24 0.09 S035 133.0 BI -23.63 0.05 S036 137.0 BI -22.85 0.10 S037 141.0 BI -23.00 0.10 S038 145.0 BI -23.39 0.10 S039 148.0 BI -23.32 0.05 S040 151.0 BI -23.74 0.08 S041 153.0 BI -24.26 0.08 S042 157.0 BI -24.43 0.06 S043 160.5 BII -24.07 0.05 S044 164.0 BII -24.28 0.08 S045 168.5 BII -23.96 0.10 S046 171 .0 BII -24.90 0.10 S047 173.0 BII -25.15 0.06 S048 174.0 BI -24.45 0.08 S049 176.0 BI -24.33 0.06 S050 178.0 C -24.39 0.06 S051 179.0 T -24.50 0.07 L001 222.7 BII -26.23 0.07 -194.0 0.3 L002 221 .3 BII -26.36 0.04 123 L003 220.0 CBI -26.74 • 0.05 -200.8 0.5 L004 218.6 BII -26.18 0.06 L005 216.3 CBI I -25.84 0.10 L006 215.9 BI -25.57 0.07 -193.0 0.3 L007 214.3 BII -26.15 0.04 -199.4 0.3 L008 212.4 BII -25.73 0.06 -197.5 0.5 L009 210.4 BII -26.11 0.06 L01 0 208.4 BII -26.06 0.11 L01 1 206.9 BI -26.30 0.03 -200.3 0.2 L01 2 205.9 CBI -24.97 0.04 -192.2 0.3 L01 3 204.9 BI -28.71 0.08 -215.1 0.2 L014 203.9 CBI -26.94 0.03 -201 .3 0.3 L01 5 202.9 BII -26.23 0.08 L016 201 .7 BII -25.29 0.02 -192.4 0.2 L01 7 200.6 C -24.38 0.07 L018 198.0 BII -23.11 0.09 -179.2 0.4 L01 9 196.0 CBI I -25.17 0.11 L020 194.0 BII -25.95 0.10 L021 192.0 BII -26.30 0.12 L022 1 90.0 BII -26.32 0.04 -199.6 0.4 L023 188.0 BII -25.22 0.03 L024 186.0 CBII -24.03 0.10 -185.8 0.2 L025 184.0 BII -23.97 0.07 L026 182.0 BII -24.25 0.09 -185.5 0.6 L027 180.0 BII -24.12 0.10 L028 1 73.0 BII -24.42 0.09 L029 171.0 BII -24.56 0.06 -186.5 0.2 L030 1 69.0 CBII -24.11 0.09 -185.4 0.5 L031 1 67.0 CBII -25.01 0.08 L032 1 65.0 CBII -25.14 0.04 -193.1 0.2 L033 163.0 CBI -24.97 0.07 -194.3 0.4 L034 161.0 CBI -25.37 0.07 L035 159.0 CBI -25.66 0.09 L036 157.0 CBI -26.06 0.10 -198.5 0.5 L037 1 55.0 CBI -24.57 0.05 L038 1 53.0 BII -24.26 0.08 -189.1 0.1 L072 150.0 BII -23. 17 0.08 L073 1 48.0 BII -22.84 0.12 -178.1 0.3 L074 146.0 BII -22.89 0.09 L075 144.0 BII -22.86 0.09 L076 142.0 BII -22.86 0.11 -177.6 0.5 L077 1 40.0 BII -22.93 0.10 L078 1 38.0 BII -23.09 0.08 -177.5 0.3 L079 136.0 BII -22.93 0.11 L080 134.0 BII -22.76 0.11 L081 132.0 BII -22.64 0.06 -177.0 0.3 L082 130.0 BII -22.66 0.06 L083 128.0 BII -22.69 0.05 -176.3 0.3 L084 1 26.0 BII -22.49 0.07 L085 124.0 BII -22.18 0.11 -174.0 0.5 L086 122.0 C -23.49 0.06 L087 120.0 C -23.41 0.09 -182.1 0.5 L088 118.0 c -23.43 0.06 124 L089 116.0 C -23.70 0.10 -182.9 0.5 L090 114.0 C -23.38 0.03 -180.4 0.5 L091 112.0 DC -23.80 0.11 -184.2 0.6 L092 110.0 DC -23.80 0.07 L093 1 08.3 DC -23.20 0.13 -180.8 0.2 L094 107.8 D -23.59 0.10 L095 107.3 D -23.72 0.09 -182.8 0.3 L096 1 06.0 DBII -23.50 0.05 L097 1 04.0 DBII -22.78 0.06 -176.9 0.2 L098 1 02.5 DBII -23.58 0.05 -183.2 0.3 J 'able A l . 7. I s o t o p i c r e s u l t s f o r BA2. Sample P o s i t i o n I c e Type S O 1 8 a (cm) S054 31 .0 B i l l -26.57 0.06 S055 33.0 B i n -25.97 0.07 S056 35.0 B I I I -26.44 0.10 S057 37.0 D -26.16 0.10 S058 38.25 D -26.43 0.06 S059 41.0 B I I I -26.56 0.09 S060 45.0 B I I I -26.47 0.08 S061 48.0 B I I I -26.49 0.06 S062 51 .5 B I I I -26.48 0.10 S063 54.0 B I I I -26.18 0.06 S064 57.0 B I I I -26.60 0.08 S065 60.0 B I I I -26.39 0.03 S066 63.0 B I I I -26.30 0.03 S067 66.0 B I I I -26.53 0.06 S068 69.0 B I I I -26.33 0.06 S069 72.0 D -26.45 0.09 S070 74.0 B I I I -26.66 0.04 S071 76.0 B I I I -27.03 0.10 S072 78.0 B I I I -27.38 0.07 S073 29.0 B I I I -25.83 0.06 S074 26.0 D -25.92 0.05 S075 23.0 B I I I -26.13 0.04 S076 20.0 B I I I -26.29 0.02 S077 17.5 B I I I -26.39 0.10 S078 15.0 D -25.71 0.09 S079 1 4.25 DBII -26.31 0.09 S080 12.25 B I I I -26.02 0.04 S081 11.0 B I I I -26.20 0.05 S082 8.0 B I I I -26.08 0.06 S083 5.0 B I I I -26.09 0.07 S084 3.0 B I I I -26.32 0.10 S085 38.0 D -25.94 0.07 S086 30.0 D -25.86 0.08 S087 1 .0 D -26.07 0.04 S089 89.0 BII -26.92 0.06 S090 86.0 BII -26.81 0.05 S091 83.0 BII -27.09 0.05 S092 80.0 BII -26.64 0.11 L039 73.75 BII -26.63 0.05 L040 71.0 BII -26.45 0.10 L041 69.0 BII -26.54 0.05 L042 67.0 BII -26.48 0.07 L043 65.0 D -26.65 0.09 L044 63.0 BII -26.59 0.07 L045 61 .0 BII -26.69 0.05 L046 59.0 BII -26.92 0.05 L047 57.0 BII -27.45 0.10 L048 55.0 BII -26.88 0.08 L049 53.0 BII -26.71 0.06 L050 51 .5 BI -26.53 0.09 L051 49.35 DBI -26.17 0.07 L052 48.25 BI -26.51 0.08 L053 47.4 DBI -26.07 0.07 L054 46.5 BI -26.33 0.09 L055 45.5 DBI -26.45 0.06 L056 44.0 BI -26.62 0.04 L057 42.0 BI -26.63 0.08 L058 40.0 BI -26.77 0.07 L059 38.5 BI -26.38 0.07 L060 38.0 DBI -25.75 0.05 L061 36.75 BI -27.25 0.04 L062 13.5 BII -25.99 0.06 L063 13.0 BII -26.32 0.05 L064 12.5 D -25.81 0.08 L065 12.0 C -25.65 0.08 L066 11.5 D -25.86 0.08 L067 10.5 BII -26.47 0.09 L068 9.25 BII -26.18 0.16 L069 7.75 BII -26.33 0.08 L070 6.25 BII -26.39 0.06 L071 4.75 BII -26. 17 0.10 APPENDIX 2. SECONDARY HEAVING MODEL A s e c o n d a r y h e a v i n g model o f o n e - d i m e n s i o n a l f r e e z i n g i n a s a t u r a t e d n o n - c o l l o i d a l s o i l has been d e v e l o p e d by R.D. M i l l e r and h i s c o l l e a g u e s ( o u t l i n e d i n M i l l e r 1980). O ' N e i l l and M i l l e r (1982) m a t h e m a t i c a l l y f o r m a l i z e d t h e q u a l i t a t i v e model i n t o a f i n i t e e l e m e n t model t o s i m u l a t e f r o s t h e a v i n g i n a s o i l c o l u m n . The c o n t r i b u t i o n of t h e i r work i s t h e c o n n e c t i o n o f t e m p e r a t u r e , p r e s s u r e and i c e c o n t e n t t o a d e p e n d e n c y on one thermodynamic v a r i a b l e , \//, w h i c h i s i n t e r p r e t e d a s t h e mean c u r v a t u r e o f t h e i c e / l i q u i d i n t e r f a c e i n a f r e e z i n g s o i l . B e c a u s e s o i l f r e e z i n g i s a slow p r o c e s s , H o l d e n (1984) s i m p l i f i e d t h e c o u p l e d n o n - l i n e a r p a r t i a l d i f f e r e n t i a l e q u a t i o n s of O ' N e i l l and M i l l e r (1982) i n t o c o u p l e d n o n - l i n e a r o r d i n a r y d i f f e r e n t i a l e q u a t i o n s . T h i s d e v e l o p m e n t g i v e s q u a s i - s t a t i c a p p r o x i m a t i o n s f o r t e m p e r a t u r e , s t r e s s , and water and i c e p r e s s u r e p r o f i l e s i n a f r o z e n f r i n g e . The H o l d e n model a l l o w s s i m p l e e v a l u a t i o n o f t h e e f f e c t o f d i f f e r e n t p a r a m e t e r s d u r i n g s o i l f r e e z i n g . The d e t a i l s of t h e models a r e c o n t a i n e d i n t h e s o u r c e p a p e r s and I w i l l o n l y o u t l i n e t h e m a j o r f e a t u r e s and a s s u m p t i o n s . The s e c o n d a r y h e a v i n g p r o c e s s i s b a s e d on t h e d e v e l o p m e n t o f a f r o z e n f r i n g e b e h i n d a f r e e z i n g p l a n e . As s o i l f r e e z e s , i c e c o n t e n t i n t h e s o i l p o r e s i n c r e a s e s i n a g r o w i n g f r o z e n f r i n g e . An i c e c o n t e n t g r a d i e n t o r f r e e e n e r g y g r a d i e n t i n t h e f r o z e n f r i n g e c a u s e s water t o move t h r o u g h a f i l m a d s o r b e d ' t o t h e s o i l g r a i n s and t o f e e d a g r o w i n g i c e l e n s . The M i l l e r model i s s a i d t o be a r i g i d i c e model w h i c h r e q u i r e s t h a t t h e i n t e r s t i t i a l i c e a l s o move t o w a r d s t h e i c e l e n s b e c a u s e of a c o n t i n u o u s i c e 127 1 28 c o n n e c t i o n t h r o u g h o u t t h e f r o z e n f r i n g e . The i c e movement i s t h e o r i z e d t o o c c u r by r e g e l a t i o n between s o i l g r a i n s . As i c e and water p r e s s u r e i n c r e a s e i n t h e p o r e s , t h e n e u t r a l s t r e s s becomes e q u a l t o t h e o v e r b u r d e n p r e s s u r e i n t h e f r o z e n f r i n g e below t h e a c t i v e i c e l e n s , and h e a v i n g o c c u r s . A s o i l l a y e r i s i n c o r p o r a t e d and a new i c e l e n s b e g i n s t o f o r m a t t h e new e q u i l i b r i u m l e v e l . T h e r e a r e t h r e e z o n e s i n t h e s e c o n d a r y h e a v i n g m o d e l : t h e upper f r o z e n zone of i c e l e n s e s and f r o z e n s o i l ; t h e f r o z e n f r i n g e of s o i l , i c e and a d s o r b e d w a t e r ; t h e l o w e r u n f r o z e n s a t u r a t e d s o i l ( F i g u r e 2 8 ) . A s y s t e m o f e q u a t i o n s c an be d e v e l o p e d f r o m e n e r g y and mass c o n s e r v a t i o n and a s s u m p t i o n s o f t e m p e r a t u r e and water p r e s s u r e r e l a t i o n s h i p s i n t h e d i f f e r e n t z o n e s . E m p i r i c a l r e l a t i o n s h i p s have been d e v e l o p e d by M i l l e r and h i s c o l l e a g u e s t o r e l a t e d i f f e r e n t p a r a m e t e r s t o t h e mean c u r v a t u r e o r t h e i c e c o n t e n t w h i c h i s a f u n c t i o n of t h e mean c u r v a t u r e . The a s s u m p t i o n s and main f e a t u r e s o f t h e H o l d e n model a r e : 1. L i n e a r t e m p e r a t u r e p r o f i l e i n t h e upper f r o z e n zone b e c a u s e of t h e l a r g e r e l e a s e o f l a t e n t h e a t . 2. L i n e a r t e m p e r a t u r e p r o f i l e i n f r o z e n f r i n g e and a s t a n d a r d e r r o r f u n c t i o n s o l u t i o n i n t h e u n f r o z e n z o n e . 3. Q u a d r a t i c w ater p r e s s u r e p r o f i l e i n t h e f r o z e n f r i n g e and l i n e a r p r e s s u r e p r o f i l e i n t h e u n f r o z e n z o ne. 4. D a r c y f l o w i n t h e f r o z e n f r i n g e and a d i s c o n t i n u i t y (jump) i n h y d r a u l i c c o n d u c t i v i t y a t t h e i n t e r f a c e 129 between f r o z e n f r i n g e and u n f r o z e n z o n e . 5. C o n s t a n t t e m p e r a t u r e a t t h e o r i g i n a l s u r f a c e and a c o n s t a n t t e m p e r a t u r e a t t h e i n t e r f a c e between f r o z e n and u n f r o z e n z o n e . 6. C o n s t a n t i c e c o n t e n t a t t h e i c e l e n s and a t t h e i n t e r f a c e between f r o z e n f r i n g e and u n f r o z e n z o n e . 7. A s t r e s s p a r t i t i o n f a c t o r between p o r e i c e and water p r e s s u r e t h a t depends upon t h e i c e c o n t e n t i n t h e f r o z e n f r i n g e . I u s e d t h e H o l d e n (1984) model t o examine t h e e f f e c t s o f d i f f e r e n t o v e r b u r d e n p r e s s u r e s and i n i t i a l s u r f a c e t e m p e r a t u r e s . I u s e d t h e same b a s i c s o l u t i o n method w i t h a few a l t e r a t i o n s . The e q u a t i o n s s i m p l i f y t o two o r d i n a r y d i f f e r e n t i a l e q u a t i o n s t h a t c an be s o l v e d i t e r a t i v e l y u s i n g a f o u r t h - o r d e r R u n g e - K u t t a scheme. H o l d e n s o l v e d t h e s t r e s s p r o f i l e i n t h e f r o z e n f r i n g e u s i n g a d i v i d e d d i f f e r e n c e t e c h n i q u e whereas I u s e d a m o d i f i e d b i s e c t i o n t e c h n i q u e . When t h e n e u t r a l s t r e s s i n t h e p o r e s e x c e e d s t h e o v e r b u r d e n p r e s s u r e , t h e new i c e l e n s i n g p o s i t i o n i s i n p u t t o t h e i t e r a t i v e p r o c e d u r e . R e s u l t s o f some a n a l y s e s a r e i n T a b l e A2. 1 . Table A2.1. R e s u l t s of s e c o n d a r y h e a v i n g a f t e r one y e a r . O v e r b u r d e n and t e m p e r a t u r e p a r a m e t e r s g i v e n . O v e r b u r d e n P r e s s u r e ( k P a ) 300 150 300 150 G l a c i e r bed s u r f a c e temp. (°C) -3 -3 -1 -1 I c e l e n s f o r m a t i o n d e p t h (m) 4.0 4.3 1.3 2.0 F r o z e n f r i n g e t h i c k n e s s (m) 0.8 0.3 1.2 0.5 C u m u l a t i v e heave (m) 0.09 0.11 0.05 0.07 1 30 The r e s u l t s have t h e f o l l o w i n g g e n e r a l p r o p e r t i e s : 1. G r e a t e r heave f o r l o w e r o v e r b u r d e n and l o w e r t e m p e r a t u r e . 2. G r e a t e r p e n e t r a t i o n of t h e f r e e z i n g f r o n t f o r g r e a t e r o v e r b u r d e n and l o w e r t e m p e r a t u r e . 3. T h i c k e r f r o z e n f r i n g e f o r g r e a t e r o v e r b u r d e n . A f t e r 1 y e a r o f g r o w t h , t h e model i s i n c o r p o r a t i n g 10-20 cm o f d e b r i s and up t o 1 cm o f i c e l e n s o v e r a p e r i o d o f 10-30 d a y s ( u s i n g p a r a m e t e r v a l u e s between t h o s e i n T a b l e A 2 . 1 ) . As t i m e i n c r e a s e s , a l l o f t h e s e f i g u r e s i n c r e a s e a l s o . 

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