UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The sedimentology, petrography and geochemistry of some Fraser Delta peat deposits Styan, William Bruce 1982

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1982_A6_7 S79.pdf [ 15.87MB ]
Metadata
JSON: 831-1.0052830.json
JSON-LD: 831-1.0052830-ld.json
RDF/XML (Pretty): 831-1.0052830-rdf.xml
RDF/JSON: 831-1.0052830-rdf.json
Turtle: 831-1.0052830-turtle.txt
N-Triples: 831-1.0052830-rdf-ntriples.txt
Original Record: 831-1.0052830-source.json
Full Text
831-1.0052830-fulltext.txt
Citation
831-1.0052830.ris

Full Text

THE SEDIMENTOLOG.Y, PETROGRAPHY AND GEOCHEMISTRY OF SOME FRASER DELTA PEAT DEPOSITS by WILLIAM BRUCE STY AN B . S c , The U n i v e r s i t y of B r i t i s h Columbia, 1976 A.THESIS SUBMITTED IN PARTIAL FULFILMENT OF-.. THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL SCIENCES We accept t h i s t h e s i s as conforming to the r e q u i r e d standard'. THE UNIVERSITY OF BRITISH COLUMBIA NOVEMBER 1981 © W i l l i a m Bruce Styan, -1 96 1 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission for extensive copying of t h i s thesis for s c h o l a r l y purposes may be granted by the head of my department or by his or her representatives. It i s understood that copying or p u b l i c a t i o n of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. The University of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date DE-6 (2/79) i i ABSTRACT On t h e r e c e n t l o b e o f t h e F r a s e r R i v e r D e l t a , p e a t d epo-s i t i o n i s o c c u r r i n g i n t h r e e d i s t i n c t s e t t i n g s : t h e d i s t a l d e l t a p l a i n , t h e t r a n s i t i o n a l u p p e r d e l t a t o l o w e r d e l t a p l a i n , and t h e u p p e r d e l t a p l a i n t o a l l u v i a l p l a i n . E a c h de-p o s i t i o n a l s e t t i n g c o n t a i n s a u n i q u e s e q u e n c e of l i t h o f a c i e s a n d b i o f a c i e s . D i s t a l l o w e r d e l t a p l a i n p e a t s , a l t h o u g h w i d e s p r e a d , f o r m a t h i n , d i s c o n t i n u o u s p e a t n e t w o r k d o m i n a t e d by a s e d g e -g r a s s f a c i e s . The p e a t s c o n t a i n numerous i n t e r c a l a t i o n s o f s i l t and s i l t y c l a y , w i t h a m o d e r a t e t o h i g h pH and a h i g h c o n c e n t r a t i o n of s u l p h u r v a l u e s . The p e a t s o v e r l i e a t h i n f l u v i a l s e q u e n c e , w h i c h i n t u r n o v e r l i e s a t h i c k c o a r s e n i n g upward s e q u e n c e o f p r o d e l t a c l a y and s i l t y c l a y . P e a t s f r o m t h i s e n v i r o n m e n t w i l l f o r m t h i n l e n t i c u l a r seams o f h i g h a s h and h i g h s u l p h u r c o a l . The c o a l m a c e r a l p r e c u r s o r s i n t h e p e a t s u g g e s t t h a t t h e b a s e o f t h e c o a l w i l l be c o m p r i s e d m a i n l y o f d e s m o c o l 1 i n i t e , w h e r e a s n e a r t h e t o p of t h e seam o x y f u s i n i t e , m a c r i n i t e , and i n t e r l a m i n a t e d c u t i n i t e and v i t -r o d e t r i n i t e w o u l d be common. I n i t i a l l o w e r d e l t a p l a i n - u p p e r d e l t a p l a i n p e a t s d e v e l -oped f r o m i n t e r d i s t r i b u t a r y b r a c k i s h m a r s h e s . High c o n c e n t r a -t i o n s o f s u l p h u r and a s h i n t h e s e p e a t s d e c r e a s e d i n o v e r -l y i n g f r e s h w a t e r s e d g e - g r a s s f a c i e s a s t h e d e l t a p r o g r a d e d and t h e n a t u r a l l e v e e s f o r m e d . Sphagnum d o m i n a t e d c o m m u n i t i e s i i i e v e n t u a l l y s u c c e e d e d i n a r e a s where f l u v i a l i n f l u e n c e was m i n i m a l . L a t e r a l l y , however, a l o n g a c t i v e c h a n n e l m a r g i n s , s e d g e - g r a s s p e a t s i n t e r c a l a t e w i t h s i l t y c l a y o v e r b a n k and s a n d y s p l a y d e p o s i t s . A t h i n f l u v i a l u n i t o f f i n i n g upward s a n d , s i l t a n d c l a y and a t h i c k s e q u e n c e of c o a r s e n i n g upward p r o d e l t a c l a y a n d s i l t y c l a y u n d e r l y t h e d e p o s i t . T h e s e p e a t s w i l l f o r m r e l a t i v e l y t h i c k , w i d e s p r e a d c o a l seams. The seams w i l l be t h i n a n d p o s s i b l y d i s c o n t i n u o u s a d j a c e n t t o c h a n n e l s and a r e a s where e x t e n s i v e s p l a y i n g h a s o c c u r r e d . H i g h s u l p h u r c o n c e n t r a t i o n s w i l l be c o n f i n e d t o t h e b a s e o f seams. The m a c e r a l p r e c u r s o r s s u g g e s t t h a t i n t e r b a n d e d t e l e n i t e , c u -t i n i t e a n d c e r e n i t e w i l l be a b u n d a n t i n t h e b a s e o f t h e seam and w i l l g r a d e v e r t i c a l l y i n t o s u b e r i n i t e , t e l o c o l l i n i t e , a nd t e l e n i t e r i c h c o a l . Stumps w h i c h w i l l f o r m m a s s i v e t e l e n i t e w i l l o c c u r l o c a l l y . A l l u v i a l p l a i n p e a t s a c c u m u l a t e d i n f r e s h w a t e r backswamp e n v i r o n m e n t s . E a r l i e s t s e d g e - c l a y a n d g y t t j a e p e a t s d e v e l o p e d o v e r t h i n f i n i n g upward c y c l e s o f s i l t y s a n d , s i l t and c l a y a n d i n t e r l a m i n a t e d s i l t , a n d s i l t y c l a y o f f l o o d o r i g i n . O v e r -l y i n g s e d g e g r a s s and Sphagnum p e a t s a r e h o r i z o n t a l l y s t r a t i -f i e d a nd f o r m s h a r p c o n t a c t s w i t h . b o r d e r i n g f l o o d s e d i m e n t s , a t a c t i v e c h a n n e l m a r g i n s , s e d g e - g r a s s p e a t s i n t e r c a l a t e w i t h o v e r b a n k s i l t y c l a y t o f o r m w e l l d e v e l o p e d n a t u r a l l e v e e s , t h e s e p e a t s w i l l f o r m a t h i c k seam o f h i g h q u a l i t y c o a l . The m i c r o l i t h o t y p e c o m p o s i t i o n i s c o m p r i s e d o f v i t r i t i c c a r b a r -g i l l i t e s a n d l i p t i t e s n e a r t h e b a s e o f t h e seams, and w i l l s h i f t t o a c l a r i t e and t h e n p r i m a r i l y v i t r i t e n e a r t h e t o p . i v Compared t o d e l t a p l a i n p e a t s , m a c e r a l d i s t r i b u t i o n w i l l be l e s s c o m p l e x . V TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES 1 v i i i LIST OF FIGURES 1 i x LIST OF TABLES 2 xv LIST OF FIGURES 2 x v i LIST OF PLATES 2 x v i i ACKNOWLEDGEMENTS x v i i i INTRODUCTION •'. 1 PART I: SEDIMENTOLOGY OF SOME FRASER RIVER DELTA PEAT DEPOSITS ABSTRACT 3 INTRODUCTION 5 REGIONAL SETTING • 8 METHODS 10 RESULTS 13 Boundary Bay 13 Lulu Island 21 P i t t Meadows 44 DISCUSSION AND CONCLUSIONS 59 L i t h o f a c i e s and D e p o s i t i o n a l S e t t i n g 59 B i o f a c i e s and Peat Stratigraphy 62 Clay Mineralogy 69 Geochemistry 70 Fraser River Delta Peats As Coal Deposits 77 SUMMARY 80 REFERENCES 84 PART I I : PETROGRAPHY OF SOME FRASER RIVER DELTA PEAT DEPOSITS ABSTRACT 93 INTRODUCTION 96 REGIONAL SETTING 98 METHODS 105 RESULTS 108 Peat D e s c r i p t i o n 108 Sedge-clay Peat 108 G y t t j a Peat 110 Sedge-Grass Peat 112 Sedge-Wood Peat 116 Sedge-Sphagnum Peat 118 Nuphar Peat 121 Sphagnum Peat 123 Eric a c e o u s Sphagnum Peat 126 Decompositional Pathways ...128 Decomposition of Juncus spp., Carex spp., and Other Sedge-Grass P l a n t s 128 Decomposition of Ledum groenlandicum. Kalmia a n g u s t i f o l i u r o . Vaccinium spp., and Oxvcoccus q u a d r i p e t a l u s 130 Decomposition of Nuphar l u t e a yar. p o l v s e p a l a ...133 Decomposition of Rhynchospora a l b a 134 Decomposition of Pinus c o n t o r t a 135 Decomposition of Sphagnum spp 137 Decomposition of Other P l a n t Tissues 138 v i i DISCUSSION AND CONCLUSIONS 140 Peat Types 140 Maceral Formation 149 SUMMARY 157 LIST OF REFERENCES 182 L I S T OF TABLES 1 T a b l e 1 Summary o f d e p o s i t i o n a l p a r a m e t e r s p. 61 T a b l e 2 C l a y m i n e r a l o g y p. 71 T a b l e 3 S u l p h u r c o n t e n t i n p e a t f a c i e s p. 74 i x LIST OF FIGURES 1 1. Location map of study areas, showing recent d e l t a i c sediments and peat deposits of the Fraser River d e l t a . p # 6 2a. An exposure of Boundary Bay peat at 112th Street shows the highly eroded and altered condition which has r e s u l t e d from the recent marine transgression. Peats are p a r t i a l l y covered with s i l t y clay and sand, the scale i s 30 cm long. p > 1^_ 1 5 2b. The fibrous texture of the sedge-grass peat i s v i -s i b l e in t h i s block. Horizontal components are com-p l e t e l y decomposed, and those tissues which are v i -s i b l e are stems which have grown v e r t i c a l l y through the e a r l i e r peat. The peat block i s 25 1 4 - 1 5 cm. wide. 2c. The highly reducing environment i s exposed just beneath the sediment surface by t h i s f o o t p r i n t . Zostera (Z) and pelecypods (P) are f a i n t l y v i s i b l e on the sediment surface. p > 14-15 3. cross-section of the discontinuous peat horizons at 112th Street, Boundary Bay. The cross section i s per-pendicular to the shoreline. The numbers are core points. p - 1 8 X F i g . 4 . P h o t o g r a p h o f c o r e f r o m B o u n d a r y Bay, s h o w i n g p e a t s t r a t i g r a p h i c u n i t s . I l u l e r i s 30 cm l o n g . p > 1 9 F i g . 5. P e a t p r o f i l e f r o m B o u n d a r y Bay, s h o w i n g p e a t t y p e s , m a c r o s c o p i c p l a n t c o n s t i t u e n t s , and a n a l y s i s of pH, s u l p h u r , and d r y a s h . p, 22 F i g . 6. L i t h o f a c i e s map o f t h e L u l u I s l a n d d e p o s i t . D ashed l i n e s show l i n e a r c h a n n e l m a r k i n g s v i s i b l e f r o m a e r i a l p h o t o g r a p h s . p. 25 F i g . 7 . I s o p a c h map o f L u l u I s l a n d d e p o s i t . E l o n g a t e l i g h t e r a r e a s r e p r e s e n t r e g i o n s where c h a n n e l a c t i v i t y was a b a n d o n e d l a t e s t . . p. 27 F i g . 8 . c r o s s - s e c t i o n s A-A', B-B' f r o m t h e L u l u I s l a n d d e-p o s i t , c h a n n e l s ( c ) r e d u c e p e a t t h i c k n e s s , w h i l e s p l a y d e p o s i t s ( s ) i n t e r r u p t t h e p e a t s u c c e s s i o n . F i g . 7 shows l o c a t i o n o f c r o s s - s e c t i o n s . L e g e n d i s i n F i 9 - 3 - p. 28 F i g . 9. C r o s s - s e c t i o n s C - C , D - D ' f r o m t h e L u l u I s l a n d d e-p o s i t . N o t e s m a l l c h a n n e l ( c ) w i t h i n p e a t i n c r o s s -s e c t i o n C ~ C . F i g . 7 shows l o c a t i o n of c r o s s - s e c -t i o n s . Legend i s i n F i g . 3 . p > 29 F i g . 10. c r o s s - s e c t i o n s E - E ' , F - F ' f r o m t h e L u l u I s l a n d d e-p o s i t . Dashed l i n e on s e c t i o n E - E ' shows f o r m e r p e a t Xi. surface p r i o r to mining. Note also truncation of the t h i c k e s t peat section by the Fraser River at El, and f i r e splay (fs.) in section F-F'. F i g . 7 shows loca-t i o n of cross-sections. Legend i s in F i g . 3. p. 3 0 F i g . 11a. The modern brackish sedge-grass marsh developed between the two arms of the Fraser River on Lulu I s l a n d . p. 3 2 - 3 3 F i g . 11b. A peat section at Lulu Island. At the base of the scale (30 cm), the boundary between Sphagnum and sedge-grass b i o f a c i e s i s v i s i b l e . p. 3 2 - 3 3 F i g . 11c. A close-up of the fibrous texture of sedge-grass peats. This peat represents organic accumulations from environments shown in F i g . 11a. p. 32-33 F i g . 12a. Ericaceous Sphagnum community, showing new growth of Pinus contorta r e s u l t i n g from drainage at Lulu I s l a n d . Largest Pinus are between 5 and 6 m t a l l . Pter idium and Ledum are growing between Pinus stands. p > 3 4 - 3 5 F i g . 12b. Ericaceous Sphagnum peat with the d i s t i n g u i s h i n g f i n e fibrous texture and f l a t t e n e d stems of Ledum (L ) . The peat block i s approximately 15 cm wide. p. 3 4 - 3 5 F i g . 12c. E r o s i o n o f t h e p e a t a l o n g t h e s o u t h e r n m a r g i n of t h e L u l u I s l a n d d e p o s i t r e v e a l s a P i n u s stump i n sedge-wood p e a t , u n i t s o f s i l t y c l a y f r o m e a r l i e r o v e r b a n k d e p o s i t s (o) a r e i n t e r c a l a t e d w i t h t h i s p e a t a s w e l l . p. 34-35 F i g . 13 P e a t p r o f i l e f r o m L u l u I s l a n d showing p e a t t y p e s , m a c r o s c o p i c p l a n t c o n s t i t u e n t s and a n a l y s i s o f pH, s u l p h u r and d r y a s h . H i g h a s h v a l u e s a t a d e p t h o f 2.5 m r e s u l t f r o m i n c o r p o r a t i o n o f s p l a y s e d i m e n t i n t o t h e p e a t . p. 40 F i g . 14. P e a t p r o f i l e f r o m L u l u I s l a n d , s h o w i n g p e a t t y p e s , m a c r o s c o p i c p l a n t c o n s t i t u e n t s , and. a n a l y s i s o f pH, s u l p h u r and d r y a s h . N o t e l a r g e i n c r e a s e i n amount o f s u l p h u r a t a d e p t h o f 3 m. p. 41 F i g . 15. P e a t p r o f i l e f r o m L u l u I s l a n d , s h o w i n g p e a t t y p e s , m a c r o s c o p i c p l a n t c o n s t i t u e n t s , and a n a l y s i s o f pH, s u l p h u r , and d r y a s h . H i g h a s h v a l u e s n e a r t h e s u r -f a c e o f t h i s c o r e r e s u l t f r o m r e c e n t o v e r b a n k d e p o s i t s . p. 42 F i g . 16. L i t h o f a c i e s map o f t h e P i t t Meadows d e p o s i t . D a s h e d l i n e s show l i n e a r c h a n n e l f e a t u r e s v i s i b l e f r o m a e r i a l p h o t o g r a p h s . p. 46 F i g . 17. l s o p a c h map o f t h e P i t t Meadows d e p o s i t . D a r k e r x i i i areas show increased peat thickness as a resu l t of i n f i l l i n g of former avulsed channels. p. 48 Fi g . 18. Cross-sections A-A', B-B' from the P i t t Meadows de-p o s i t . Note avulsed channel (c) in cross-section B-B' increases peat thickness, whereas a more recent, l a r g e r channel has truncated the thickes t peats at both A and B. F i g . 17 shows l o c a t i o n of cross-sec-t i o n s . Legend i s in F i g . 3. p. 49 F i g . 19. Cross-sections C-C, D-D' from the P i t t Meadows de-p o s i t . Small flood channels (c) are moire evident in these two cross-sections. F i g . 17 shows location of cros s - s e c t i o n s . .Lsgend i s in F i g . 3. p. 50 F i g . 20. Cross-sections E-E', F-F' from the P i t t Meadows de-p o s i t . On both cross sections, at E' and F', i n t e r -lamination of peat and overbank s i l t y clay form the natural levee f a c i e s . F i g . 17 shows l o c a t i o n of cro s s - s e c t i o n s . Legend i s in F i g . 3. p- 51 F i g . 21. peat p r o f i l e from P i t t Meadows, showing peat types, macroscopic plant constituents, and an a l y s i s of pH, sulphur, and dry ash. unlike Lulu Island, pH values become more a l k a l i n e with depth and sulphur remains constant. p. 55 22. peat p r o f i l e from Pitt' Meadows, showing peat types, x i i v macroscopic plant constituents, and analysis of pH, sulphur and dry ash. p. 56 F i g . 23. Peat p r o f i l e from P i t t Meadows, showing peat types, macroscopic plant constituents, and analysis of pH, sulphur and dry ash. This p r o f i l e represents the na-t u r a l levee, and therefore ash contents are very high as a r e s u l t of i n t e r c a l a t e d overbank deposits. p. 57 F i g . 24. cummary model of peat r e l a t i o n s h i p s with other l i -t h ofacies within the d i s t a l lower d e l t a p l a i n environment. p. 53 F i g . 25. Summary model of peat r e l a t i o n s h i p s with other l i -t h o facies within the t r a n s i t i o n a l lower delta p l a i n -upper d e l t a p l a i n environment. Legend for diagram i s in F i g . 24. p. 64 F i g . 26. summary model of peat r e l a t i o n s h i p s with other l i -t h ofacies within the upper delta p l a i n - a l l u v i a l p l a i n environment. Legend for diagrams i s in F i g . 24. p: 65 F i g . 27. percent ash versus c a l o r i f i c value plot for analysis of major peat b i o f a c i e s . p. 76 X V L I S T OF TABLES 2 T a b l e 1 Summary o f t h e c h a r a c t e r i s t i c s of t h e v a r i o u s p e a t t y p e s . p. 141-142 T a b l e 2 Some p l a n t t i s s u e s a n d t h e p r o b a b l e c o a l m a c e r a l s ( m a c e r a l g r o u p s ) d e r i v e d f r o m them. p. 145-146 T a b l e 3 P e a t t y p e s and a s s o c i a t e d c o a l m a c e r a l s p. 147-148 X V I LIST OF FIGURES 2 Figure 1 Peat Successional Sequence p. 101 Figure 2 Summary: Petrographic Method p. 107 r X v i i L I S T OF PLATES 2 P l a t e 1 : F i g u r e s 1-5 M a r i n e s e d g e - g r a s s p e a t P - 1 6 3 P l a t e 2: F i g u r e s 1-5 B r a c k i s h s e d g e - g r a s s p e a t P - 1 6 5 P l a t e 3 : F i g u r e s 1-5 F r e s h w a t e r s e d g e - g r a s s p e a t P - 167 P l a t e 4: F i g u r e s 1-5 Sedqe-Sphaqnum p e a t P - 169 P l a t e 5: F i g u r e s 1-5 Sedge-wood p e a t P - 1 7 1 P l a t e 6: F i g u r e s 1-5 Nuphar p e a t P - 1 7 3 P l a t e 7: F i g u r e s 1 -5 Sphagnum p e a t P - 1 7 5 P l a t e 8: F i g u r e s 1-5 E r i c a c e o u s Sphaqnum p e a t P - 177 P l a t e 9 : F i g u r e s 1-5 D e c o m p o s i t i o n P - 1 7 9 P l a t e 10: F i g u r e s 1-5 D e c o m p o s i t i o n P - 1 8 1 \ XV i i i ACKNOWLEDGEMENTS . I s i n c e r e l y thank Dr. R. Marc Bustin for o f f e r i n g d i r e c -tio n , assistance, advice, and encouragement throughout a l l stages of t h i s p r o j e c t . I am also g r a t e f u l to Dr. G.E. Rouse for his enthusiasm and assistance in plant anatomy, palynolo-gy, and peat ecology, and to Drs. W.C. Barnes and M.A. Barnes for s c i e n t i f i c advice and for c r i t i c a l l y reading the manus-c r i p t . Appreciation i s also extended to Dr. L. Lavkulich and Dr. L.E. Lowe of the Department of S o i l Science, for t h e i r help with c l a y mineralogy and sulphur analysis, and to Dr. J. Maze of the Department of Botany for his assistance in the preparation of microtome sections. I would also l i k e to thank G. Hodge and B. Martin for the d r a f t i n g and R. Crosby for the typing of the manuscript. F i n a l l y , I thank my two able a s s i s t a n t s , Tom and Dave, for invaluable help in the lab and the f i e l d . Scott and Jean Carmichael, Jane Shepperd, Jack Styan, and Sandi Olsen also, assisted iri the fieldwork. Suzanne Hebert Styan was patient and understanding during the many hours of study. The re-search was funded by N.A.H.S. (U.B.C.) and N.S.E.R.C. (67-7337) grants to R. Marc Bustin. 1 INTRODUCTION In the p a s t , most r e s e a r c h i n t o the t r a n s f o r m a t i o n of peat to c o a l c o n c e n t r a t e d s o l e l y on the i n t e r p r e t a t i o n s of c o a l and surrounding sediment. L i t t l e a t t e n t i o n was g i v e n to the study of modern a n a l o g s . The s i t u a t i o n has changed r e -c e n t l y , however. Cohen and Spackman (1980) and Koch (1966, 1970) have s t u d i e d the o r i g i n s of i n d i v i d u a l macerals from p a r t i a l l y decayed s u r f a c e l i t t e r , while Given (1972), Casagrande (1970), and Casagrande and Park (1978) have ob-served changes i n s p e c i f i c b i o c h e m i c a l groups as they decom-pose from l i v i n g p l a n t s to u n d e r l y i n g peats. The o r i g i n of sulphur i n peat and the i m p l i c a t i o n s f o r c o a l d e p o s i t s has been documented by Casagrande and S i e f e r t (1977), Casagrande and Ng (1979), Given and M i l l e r (1971), and Casagrande et a l . (1976, 1978, 1979). S t u d i e s by Anderson (1964), Cohen (1968, 1974), Cohen and Spackman (1977), Cohen and Ti n g (1978), F i s k (1960), Gleason et a l . (1980), Spackman et a l . (1974), and Staub and Cohen (1978, 1979) have l e d to the development of d e p o s i t i o n a l models. Metals i n peat have been s t u d i e d by Casagrande and E r c h u l l (1976). With the e x c e p t i o n of the i n v e s t i g a t i o n s by Koch (1966, 1970), a l l of these s t u d i e s have c o n c e n t r a t e d on peat depos-i t s from t r o p i c a l and s u b t r o p i c a l c l i m a t e s . Although peats have formed i n predominantly warm, moist c l i m a t i c zones throughout the g e o l o g i c a l p a s t , they a l s o have produced s i g -n i f i c a n t d e p o s i t s w i t h i n humid temperate or c o o l c l i m a t e s 2 ( T e i c h m u l l e r and T e i c h m u l l e r , 1975 and o t h e r s ) . F r a s e r R i v e r d e l t a peats are forming under moist temperate c o n d i t i o n s , and thus p r o v i d e an a l t e r n a t i v e c l i m a t i c s e t t i n g i n which to de-v e l o p s e d i m e n t o l o g i c a i and geochemical models. In the f i r s t s e c t i o n of t h i s t h e s i s the v a r i o u s b i o f a -c i e s and l i t h o f a c i e s are i d e n t i f i e d and d e s c r i b e d from three peat forming environments. The s t r a t i g r a p h i c r e l a t i o n s h i p s between these two components are then determined and i n t e -g r a t e d to produce i n d i v i d u a l g e o l o g i c a l models. Measurements of pH, sulphur and ash a i d in r e l a t i n g peat q u a l i t y to en-v i r o n m e n t a l s e t t i n g . The second p o r t i o n of the t h e s i s i d e n t i f i e s and de-s c r i b e s i n d i v i d u a l peat types and' determines the e a r l y b i o -chemical stages of degradation through o b s e r v a t i o n of s p e c i f -i c p l a n t t i s s u e s , u s i n g p e t r o g r a p h i c techniques m o d i f i e d from Cohen and Spackman (1972). These d e c o m p o s i t i o n a l processes are then u t i l i z e d to provide a h y p o t h e t i c a l b a s i s f o r the formation of p a r t i c u l a r c o a l macerals and m i c r o l i t h o t y p e s . 3 PART I: SEDIMENTOLOGY OF SOME FRASER RIVER DELTA PEAT DEPOSITS ABSTRACT Peat accumulation has a c t i v e l y o c c u r r e d i n t h r e e d i f -f e r e n t d e p o s i t i o n a l s e t t i n g s on the Recent lobe of the F r a s e r River d e l t a : the d i s t a l lower d e l t a p l a i n , the t r a n s i t i o n between upper and lower d e l t a p l a i n s , and the t r a n s i t i o n be-tween upper d e l t a p l a i n and a l l u v i a l p l a i n . D i s t a l lower d e l t a p l a i n peats were not i n f l u e n c e d ap-p r e c i a b l y by f l u v i a l a c t i v i t y , and developed from widespread s a l t and b r a c k i s h marshes. L a t e r a l development of these marsh f a c i e s were c o n t r o l l e d by compaction and e u s t a t i c sea l e v e l r i s e . The r e s u l t i n g t h i n , d i s c o n t i n u o u s peat network c o n t a i n s numerous s i l t y c l a y laminae and h i g h c o n c e n t r a t i o n s of sulphur. Formation of freshwater marsh f a c i e s o c c u r r e d , but were l a t e r eroded and a l t e r e d by t r a n s g r e s s i n g marine waters. The peats o v e r l y a t h i n f l u v i a l u n i t of f i n i n g upward sandy s i l t and c l a y and a t h i c k c o a r s e n i n g upward se-quence of p r o d e l t a c l a y and s i l t y c l a y . Peats from t h i s en-vironment w i l l form t h i n l e n t i c u l a r c o a l seams with numerous s p l i t s and high ash and sulphur c o n c e n t r a t i o n s . Lower d e l t a p l a i n - u p p e r d e l t a p l a i n peats were i n i t i a l l y developed from i n t e r d i s t r i b u t a r y b r a c k i s h marshes, but were l a t e r f l u v i a l l y i n f l u e n c e d . The high c o n c e n t r a t i o n s of s u l -phur and ash i n the sedge-grass peats g r a d u a l l y decrease up-4 section as the delta progrades and natural levees are devel-oped. The thickest peats occur in areas where d i s t r i b u t a r y channels were abandoned e a r l i e s t . Sphagnum biofacies replace sedge-grass dominated communities except along active channel margins, where the l a t t e r i n t e r c a l a t e s with s i l t y clay over-bank and sandy splay deposits. The peats are underlain by a r e l a t i v e l y thin sequence of f i n i n g upward sand, s i l t , and s i l t y clay and then by a major coarsening upward sequence of prodelta s i l t y c l a y . Coal seams formed from these peats would be l a t e r a l l y extensive but of variable thickness and q u a l i t y . Coal near the base of seams would contain numerous s p l i t s and high sulphur concentrations. A l l u v i a l p l a i n peats accumulated in back swamp environ-ments of the flood p l a i n . E a r l i e s t sedge-clay and gyttjae peats developed over thin f i n i n g upward cycles of s i l t y sand, s i l t and clay, and interlaminated clay and s i l t y clay of flood o r i g i n . Thickest peat accumulations occur where these facies f i l l small avulsed flood channels. Overlying sedge-grass and Sphagnum bi o f a c i e s are h o r i z o n t a l l y s t r a t i f i e d and commonly form sharp boundaries with fine grained flood sedi-ments. At active channel margins, however, sedge-grass peats prograde v e r t i c a l l y to i n t e r c a l a t e with s i l t y clay and form well developed natural levees. These levees reduce both the number and size of crevasse splay deposits. Representing the culmination of a major f i n i n g upward sequence, these peats w i l l form a thick, i s o l a t e d seam of coal with low ash and sulphur concentrations. 5 INTRODUCTION The most recent lobe of the Fraser River delta complex is the product of active progradation of the Fraser River since the culmination of the l a s t g l a c i a l stade 11,500 years ago. A large area of the modern delta i s of extremely low r e l i e f , and thus conducive to the i n i t i a l development of marsh and raised bog deposits. Peats of approximately the same age began accumulating in several d i f f e r e n t depositional environments in response to a marked slowing in the rate of eustatic sea l e v e l r i s e around 4,500 years B.P. (Fairbridge, 1976; Rampino and Sanders, 1981). From these various depos-i t i o n a l environments, peat forming areas at Boundary Bay, Lulu Island and P i t t Meadows were selected for study (Fig. 1). At Boundary Bay, peats accumulated from s a l t and brack-ish marshes on an inactive portion of the d i s t a l lower delta p l a i n . As a r e s u l t , these peats were not influenced appre-ci a b l y by f l u v i a l a c t i v i t y . Deposit boundaries of lower-upper delta p l a i n peats at Lulu Island, however, were con-t r o l l e d by f l u v i a l processes. Correspondingly, early brack-ish water peats in these deposits were gradually replaced by freshwater marsh equivalents. Upper delta p l a i n - a l l u v i a l p l a i n peats at P i t t Meadows originated from freshwater marshes, but l i k e lower-upper delta p l a i n peats, were i n f l u -enced considerably by f l u v i a l sedimentation. The unique en-vironmental settings of these deposits provide an excellent Fig. 1. Location map of study areas, showing recent d e l t a i c sediments and peat deposits of the Fraser River d e l t a . 7 opportunity to compare r e s u l t i n g differences in sedimentolo-gy, petrography and geochemistry. Because peat is the pro-genitor of coal, these differences can be extrapolated and applied to produce models which may aid in the understanding of ancient coals and coal-bearing s t r a t a . 8 REGIONAL SETTING The Fraser River i s more than 1200 km long, and has a drainage area in excess of 230,000 km2 (Milliman, 1980). A t o t a l sediment load of between 12 and 30 m i l l i o n tons, con-s i s t i n g of equal amounts of s i l t and sand, and up to 10% clay, i s c a r r i e d to the river mouth annually (Mathews and Shepard, 1962). The sediments, which originate from Pleistocene g l a c i a l deposits, result in the progradation of the delta by as much as 9 m per year. The sand i s deposited primarily in channels and in low islands at the mouths of channels. Part of the sediment is r e d i s t r i b u t e d by longshore currents to form shallow bars. In areas of the delta front not influenced by f l u v i a l sedimentation, wave action winnows out finer sediments to produce sandy t i d a l f l a t s (Luternauer and Murray, 1973). S i l t s and clays accumulate with organic muck in i n t e r d i s t r i b u t a r y troughs and on the delta front. The modern delta presently covers an area of 975 km2 and has an average thickness of 110 m (Mathews and Shepard, 1962). This lobe extends 31 km into the S t r a i t of Georgia from a narrow gap in Pleistocene uplands at New Westminster and forms a perimeter greater than 27 km (Luternauer and Murray, 1973) (Fig. 1). The western perimeter i s a c t i v e l y receiving sediment from two d i s t r i b u t a r y channels. However, along the southern margin from Point Roberts to White Rock, a broad, shallow t i d a l f l a t has developed where only minor sed-iment i s being added from the Serpentine and Nicomekl rivers 9 and erosion of the Point Roberts Peninsula (Shepperd, 1981). The broad delta front surrounding the perimeter has a slope of 1.5°, and i s cut by a series of g u l l i e s leading to hummoc-ky topography (Mathews and Shepard, 1962). Ti d a l range from mixed tides reaches a maximum of 5 m at the delta front. This strong t i d a l influence i s f e l t over much of the delta throughout the entire year, e s p e c i a l l y during the spring freshet (Milliman, 1980). A s a l t wedge extends as much as 20 km up r i v e r in winter, but seldom reaches past the d i s t r i b u t a r y mouths between May and July, when runoff peaks (Johnston, 1921; Swinbanks, 1979). 10 METHODS In order to determine l i t h o f a c i e s , b i o f a c i e s , and peat stratigraphy in the three deposits studied, three hundred and fi f t e e n holes were d r i l l e d , using a hand-driven H i l l e r Corer. Due to v a r i a b i l i t y in peat composition and depth, cores were spaced 100 meters apart in a l i n e a r fashion. After surveying the holes, cross sections were drawn and stratigraphic r e l a -tionships established. For areas which had been disturbed by peat cutting, sections were restored to the i r approximate thicknesses before peat isopach maps were prepared. Surface l i t h o f a c i e s were also i d e n t i f i e d and mapped. Using information from cross sections, and peat isopach maps, three uncompressed cores were obtained from each of the P i t t Meadows and Lulu Island deposits, while a seventh was colle c t e d from the Boundary Bay peat. For about the i n i t i a l meter and one-half, peat blocks measuring 20 cm x 150 cm x 50 cm were cut from the wall of a hole, using a machete. The remainder of the core was obtained using a toothed piston corer (Cohen, 1968). The piston was greased before each use and the barrel was pushed straight down without twisting. The core was then transferred to i r r i g a t i o n pipe of the same diameter and the ends sealed. This combination of methods avoided compaction which resulted when other coring devices were used. The cores were then logged and the peat subdivided into 11 smaller homogeneous units. Samples c o l l e c t e d for moisture, ash, and organic matter were stored in p l a s t i c containers. Water was added to saturate the samples. After equilibrium was attained, 30 g were placed in an oven at 105°C for 16 hours. The r e s u l t i n g weight loss was recorded, and the re-mainder of the sample was ashed in a muffle furnace at 550°C u n t i l no further weight loss occurred. The difference in weight of ash and water from the o r i g i n a l sample provided a measure of organic matter. The remainder of the core, aside from pollen, spectrographs, and clay samples, was dried at room temperatre for 16 hours. After a si m i l a r period of time in an oven at 105°C the peat was crushed, mixed, and approxi-mately '0.5 g removed for determination of heat value in an adiabatic calorimeter. Three grams of t h i s mixture were used to determine pH (ASTM D 2976-71). Sulphur samples were re-ground and sieved at 100 mesh before analysis on a Fisher ® Sulphur Analyzer. The less than 2yim clay f r a c t i o n was separated from cre-vasse splay, overbank and underclay sediments. An oriented s l i d e was prepared, and the remaining clay f r a c t i o n was sa-turated with a 1 M KCl solution for three days. After remov-a l of the KCl solution, another oriented s l i d e was prepared. Both samples were subjected to X-ray d i f f r a c t i o n using CulK^ radiation and a 002 graphite monochromator. Slides were scanned between 3° and 18°2© at 1°2© per minute, with a 2 second time constant. The K-saturated s l i d e was then heated to 300°C for 4 hours, cooled, and X-rayed again. A similar 12 procedure followed after reheating the s l i d e to 550°C. The natural s l i d e was glycolated in a desiccator for one day before being analysed a f i n a l time. Following i d e n t i f i c a t i o n of the clay minerals, the r e l a t i v e abundances were approxi-mated using the methods of Bayliss et ajL. ( 1 970). Pollen was isol a t e d from peat samples using standard methods. After screening with 250 and lOO^um sieves, samples were boiled in 5% KOH for 20 minutes and then water washed three times. This procedure was followed by two acetic acid washes and b o i l i n g in a c e t o l y s i s solution (9:1 acetic any-dride; concentrated H2SO*) for 30 minutes. Prior to staining with 10% safranin solution, the acet o l y s i s mixture was washed twice with each of g l a c i a l a c e tic acid and water and was neu-t r a l i z e d with 5% K 2C0 3 s o l u t i o n . Slides were then prepared and pollen i d e n t i f i e d . 13 RESULTS Boundary Bay a. Location and History The Boundary Bay peat i s situated on the inactive margin of the delta between the Point Roberts Peninsula and the Serpentine and Nicomekl Rivers. It extends from the foot of 112. Street towards Mud Bay and seaward into Boundary Bay. Although not v e r i f i e d , t h i s peat may also extend shoreward and connect with Burns Bog through a series of channel f i l l peats (personal communication, G.E. Rouse, 1981). The sedge-grass peats at Boundary Bay developed on the coastal portion of the lower delta p l a i n , where i t merged with the delta front. Prior to dyking, t h i s area was flooded frequently because of high ti d e s , runoff from the Fraser River freshet (Shepperd, 1981), and occasional storms. Ero-sion and a l t e r a t i o n of the peat have continued on the seaward side of the dyke, producing a discontinuous horizon p a r t i a l l y covered by s i l t y sand (Fig. 2A). In some areas a more recent salt marsh peat has developed over the older peat, but i t too is being eroded. The Boundary Bay t i d a l f l a t s have been studied by Kellerhals and Murray (1969) and Swinbanks (1979). The only extensive study on the peats, however, i s the palynological 14 Figure 2A. An exposure of Boundary Bay peat at 112th Street shows the highly eroded and a l t e r e d condition which has resulted from the recent marine transgression, peats are p a r t i a l l y covered with s i l t y clay and sand, scale i s 30 cm long. Figure 2B. The fibrous texture of the sedge-grass peat at Boundary Bay i s v i s i b l e in t h i s block, horizontal components are completely decomposed, and those t i s -sues which are v i s i b l e are stems which have grown v e r t i c a l l y through the e a r l i e r peat, the peat block i s 25 cm wide. Figure 2C. The highly reducing environment at Boundary Bay is exposed just beneath the sediment surface by t h i s f o o t p r i n t . Zostera (Z) and pelecypods (P) are f a i n t l y v i s i b l e on the sediment surface. 15 16 work by Shepperd (1981). She analysed pollen assemblages from the older peat at 112 Street, dated at between 3130±50 years bp. (GSC 3202) and 3910±60 years bp. (GSC 3183), and the much younger s a l t marsh peat at 64 Street, dated at 320±10 years bp. (GSC-3186). b. L i t h o f a c i e s Peats at Boundary Bay form l a t e r a l l y extensive accumula-tions on inactive portions of the lower delta p l a i n - d e l t a front. L i t h o f a c i e s include both marine and f l u v i a l derived sediments. Thickest peat accumulations o v e r l i e clean grey clay, which is confined primarily to upper i n t e r t i d a l and suprati-dal areas ( F i g . 3). This clay grades over 0.5 m, from an overlying organic r i c h sedge-clay, down into well sorted s i l t y clay, s i l t , and s i l t y sand. Shell debris is absent, and only trace amounts of organic matter are present. Beneath and between thinner peats in lower i n t e r t i d a l areas are grey to brown s i l t y sand and fine sand. Variation in color is c o n t r o l l e d by the r e l a t i v e amount of organic matter. These l i t h o l o g i e s appear structureless and show only s l i g h t variation in grain size with depth. D i r e c t l y beneath peats, however, f a i n t black laminae of variable thickness occur. Shell fragments are present, but constitute a minor f r a c t i o n of the sediment. Contacts between these massive units and the more shoreward graded units are sharp. A well sorted 17 medium s a n d , v e r y r i c h i n o x i d i z e d o r g a n i c m a t t e r , c o v e r s much o f t h e upper i n t e r t i d a l z o n e . T h i s u n i t ( n o t d i s t i n -g u i s h e d i n c r o s s s e c t i o n ) has a v a r i a b l e t h i c k n e s s , but s e l d o m e x c e e d s 20 cm. The b a s a l c o n t a c t i s s h a r p . c . B i o f a c i e s Two b i o f a c i e s c a n be d i s t i n g u i s h e d a t B o u n d a r y Bay ( F i g . 4). The l o w e r m o s t u n i t i s composed of a g r e y t o t a n g r e y c l a y , and r e p r e s e n t s a t r a n s i t i o n from i n o r g a n i c g r e y c l a y and s i l t y c l a y . Sedge and g r a s s l e a f and stem t i s s u e a r e b o t h v e r t i c a l l y a n d h o r i z o n t a l l y o r i e n t e d t h r o u g h o u t i t s m a s s i v e t e x t u r e . V e r t i c a l l y a l i g n e d p l a n t t i s s u e s a r e o f t e n o x i d i z e d , l e a v i n g t h i n empty t u b e s w i t h d a r k brown r i m s . B l a c k and y e l l o w r o o t l e t s a r e p e r v a s i v e . T h i s u n i t i s n e v e r more t h a n 20 cm t h i c k , and g r a d e s a b r u p t l y i n t o a l i g h t c h o -c o l a t e brown p e a t , composed e n t i r e l y o f sedge and g r a s s , l e a v e s , stems, and r o o t s ( F i g . 2B). T h e s e t i s s u e s f o r m h o r i -z o n t a l l a m i n a e w h i c h p a r a l l e l t h e b a s e of t h e d e p o s i t . T h i n c h a r c o a l bands o c c u r t o w a r d t h e m i d d l e and, l e s s commonly, t h e u p p e r s e c t i o n s o f t h e p e a t . D e g r a d a t i o n i s h i g h , and p l a n t m a t e r i a l c a n n o t be i d e n t i f i e d a t t h e g e n e r i c l e v e l . R e l a t i v e l y l a r g e numbers o f C h e n o p o d i a c e a e p o l l e n o c c u r a t t h e b a s e o f t h e p e a t , w h i l e an a s s e m b l a g e of d o m i n a n t l y C y p e r a c e a e and G r a m i n e a e p o l l e n o c c u r t h r o u g h o u t t h e r e m a i n -d e r of t h e s e d g e - g r a s s u n i t . 7 8 9 10 II 12 IS s -=r -nsr 100m 1m SCALE „ _ _u LEGEND - SPHAGNUM - SPHAGNUM-SEDGE - SEDGE-GRASS - GYTTJA - FIRE C H A R C O A L - SEDGE CLAY - INORGANIC SILT CLAY - ORGANIC SILTY CLAY - BRACKISH-MARINE SILTY SAND CO F i g . 3. C r o s s - s e c t i o n o f the d i s c o n t i n u o u s peat h o r i z o n s at 112th S t r e e t , Boundary Bay. The c r o s s - s e c t i o n i s p e r p e n d i c u l a r to the s h o r e l i n e . The numbers are core p o i n t s . 19 Fig. 4. Photograph of core from Boundary Bay, showing peat s t r a t i g r a p h i c units. Ruler i s 30 cm long. 20 e. Clay Mineralogy and Geochemistry Clays underlying sedge-grass peats at Boundary Bay~are dominated by k a o l i n i t e and i l l i t e , which together comprise, on average, 83% of a l l analyzed samples (Table 1). Smaller amounts of smectite, c h l o r i t e and vermiculite are also pre-sent. A small amount of mixed layer smectite-chlorite was also i d e n t i f i e d . Sedge-grass peats at Boundary Bay are presently being oxidized by marine water, and as a result are highly decom-posed. In the core taken from t h i s environment, BB1 (Fig. 5), t o t a l sulphur values range from 5.2 to 6.1% in sedge-grass peat, but decrease abruptly to half t h i s amount in sedge-clay peat. Dry ash values are correspondingly high., and vary from 22 to 51% throughout the section. The highest ash content coincides with charcoal horizons at a depth of 0.3 meters. PH values, near 5.8, are more alkaline than those recorded from freshwater peats. Depositional History Boundary Bay peats have a complex depositional h i s t o r y . I n i t i a l peats began developing between d i s t r i b u t a r y channels and were freshwater in o r i g i n . After these channels were abandoned, about 4,500 years B.P. (G. Rouse, personal com-munication, 1981), a large portion of the delta margin became inactive. Brackish marshes then developed in low-lying areas 21 over extensive areas of the lower delta p l a i n . As the rate of eustatic sea l e v e l rise slowed, brackish marsh peats spread quickly over previously deposited freshwater marsh peats, floodplain s i l t y clays, and sandy marine s i l t s . Marsh growth was pervasive, except in areas which were continually influenced by t i d a l a c t i v i t y . Accumulation of plant material i n i t i a l l y kept pace or exceeded euastatic sea l e v e l r i s e , and i s o l a t e d peats coa-lesced to form larger deposits. Freshwater peats gradually replaced brackish water equivalents in areas where the sub-strate had been elevated above t i d a l i n f l u x . Throughout peat accumulation, storm events, Fraser River freshets, and ex-treme high tides intermittently deposited s i l t or s i l t y clay into the peat as thin discontinuous lenses. Eventually the slower growth of the freshwater marsh peat, sediment compac-tio n , and/or an increased rate of eustatic sea l e v e l r i s e allowed the peat to be inundated and covered by s i l t s . A l l growth ceased and the peat was l a t e r a l t e r e d and eroded by wave and t i d a l action. Lulu Island a. Location and History The Greater Lulu Island Bog extends from near the centre of Lulu Island east to the main arm of the Fraser River (Fig. 1 ) . As part of an extensive network of bogs which de-BB M A C R O S C O P I C CONSTITUENTS Q_ UJ O 0 -i * « 0.2 -a. x 0.4 - C X • a - k _ ±_ * 0.6 -C i r t x slam J u n c t i t t «m o o o ol o * Jt * Sphagnum peat sedge-Sphagoum peat sedge-grass peat * * « | sedge-clay peat PH 3.0 4.0 5.0 6.0 T r 4N A A LEGEND ] gyttj« iae o D ° Nuphar peat silt % T O T A L 1 SULPHUR 0 2.0 4.0 6.0 % DRY A S H 0 5 10 15 20 :):[(-}:/--; sand " • | petrography sample fire horizon, charcoal Fig. 5. Peat p r o f i l e from Boundary Bay, showing peat types, macroscopic plant constituents, and analysis of pH, sulphur, and dry ash. ro 23 veloped at approximately the same time, i t has been cut into two halves by a northeasterly-trending channel. The eastern portion of t h i s deposit was studied with 150 hand-driven H i l l e r cores (Fig. 1). The bog l i e s on the boundary between lower and upper delta p l a i n s . During the freshet flow in spring and early summer the area i s influenced only by fresh water. Through-out the remainder of the year, r i v e r flow i s r e l a t i v e l y low, and saline bottom waters extend past the Lulu Island bog (Milliman, 1980). Mixing occurs such that even surface waters are s l i g h t l y brackish for a period of time. In 1927, Hugo Osvald observed the bog in a r e l a t i v e l y undisturbed state, and described surface plant associations from numerous c o l l e c t i o n s (Osvald, 1928, 1933, 1970). Hansen (1940) studied the paleoecology using pollen analysis from a core in the western portion of the bog. L i t t l e s c i e n t i f i c study has occurred since. The deposit was ditched and subsequently mined for peat early in the century. Although large areas of peat were cut, primitive c u t t i n g methods prevented mining of large s t r i p s of the natural bog surface. Only in the northwestern area, where active mechanized mining i s presently occurring, has the peat surface been destroyed completely. However, much of the eastern portion of the deposit i s a c t i v e l y being covered with garbage and dredged f l u v i a l sand. To the west and 24 north, blueberry farms and nurseries make more conventional use of the bog. b. L i t h o f a c i e s The Lulu Island peat developed within a f l u v i a l dominated lower delta plain environment. Through d e l t a i c growth the f l u v i a l network has gradually acquired the charac-t e r i s t i c s of an upper delta p l a i n . L i t h o f a c i e s deposited r e f l e c t these changes. Small channel deposits and channel f i l l deposits are recognized in bog cross-sections as depositional features which reduce peat thickness (Figs. 6-10). Most channel f i l l s consist of sedge-peat and clay (Fig. 8), and are flanked by levees composed of interlaminated s i l t and clay which in turn grade l a t e r a l l y into f i n e r i n t e r d i s t r i b u t a r y clay units. In some channels, however, fi n i n g upward sequences of s i l t and fine to medium sand replace sedge peat and clay in the core. These c l a s t i c sediments grade upward into highly rooted tan clay and eventually peat. Near the t r a n s i t i o n to organic facies. intercalated fine sand to s i l t y crevasse units (Figs. 8-10) occasionally occur. These units are l a t e r a l l y extensive, becoming thinner and f i n e r grained toward the center of the bog. Intensive rooting by l a t e r sedge-grass communities has destroyed most bedding structures and has added considerable organic content. Some grading and a sharp basal contact are s t i l l v i s i b l e . to Fig. 6. L i t h o f a c i e s map of the Lulu Island deposit. Dashed l i n e s show l i n e a r channel markings v i s i b l e from a e r i a l photographs. 26 Large channel deposits consisting of f i n i n g upward s i l t and sand units confined the l a t e r a l development of the bog. These sediments are mantled by up to 2 m of s i l t y clay and bounded l a t e r a l l y by broad natural levees consisting of interlaminated peat and s i l t y c lay. At depth, clay replaces peat and in turn i s replaced by fine sand. Marginal to chan-nels, h o r i z o n t a l l y r e s t r i c t e d crevasse splays comprised of fine to medium sand interrupt peat deposition at ir r e g u l a r intervals (Figs. 8-10). These units average 15 cm thick and thin rapidly over short distances within the peat. Isolated lenses of grey organic s i l t y clay and clay occur occasionally within sedge peat. Charcoal fragments are common, and increase in density toward the base of these thin f i r e splay u n i t s . The basal contact i s sharp with underlying gyttja, while the upper contact i s highly rooted and grada-t i o n a l . c. Biofacies . Lulu Island b i o f a c i e s depict a natural successional se-quence leading to the formation of an oligotrophic raised bog (Styan and Bustin, 1981). Sedge-clay peat represents the i n i t i a l t r a n s i t i o n from f l u v i a l to organic sedimentation. Accordingly, t h i s peat i s composed of both organic and inor-ganic components. The organic constituents include a l l o c h -thonous wood and bark fragments and autochthonous Equisetum and sedge stem and root tissues. Addition of these materials Fig. 7. Isopach map of the Lulu Island deposit. Elongate l i g h t e r areas represent regions where channel a c t i v i t y was abandoned l a t e s t . Co Fig. 8. Cross-sections A-A', B-B' from the Lulu Island deposit. Channels (c) reduce peat thickness, while splay deposits (s) i n t e r u p t the peat succession. Fig. 7. shows the l o c a t i o n of c r o s s - s e c t i o n s . Legend i s in Fig. 3. Fig. 9 . Cross-sections C-C, D-D1 from the Lulu Island deposit. Note small channel (c) within peat in cross-section C-C. Fig. 7. shows the l o c a t i o n of the c r o s s - s e c t i o n s . Legend i s in Fig. 3. r-j VD O Fig. 10. Cross-sections E-E', F-F' from the Lulu Island deposit. Dashed l i n e on section E-E' shows former peat surface p r i o r to mining. Note also truncation of the t h i c k e s t peat section by the Fraser River at E7, and f i r e splay (fs) in s e c t i o n F-F 1. F ig. 7. shows l o c a t i o n of c r o s s - s e c t i o n s . Legend i s in Fig. 3. 31 t o m a s s i v e t a n - g r e y c l a y p r o d u c e s a f i b r o u s t o g r a n u l a r s e d i -ment. Most p l a n t components o f t h e s e p e a t s a r e h i g h l y decom-p o s e d . As f l u v i a l i n f l u e n c e d e c r e a s e d , s e d g e - g r a s s p e a t s became do m i n a n t ( F i g s . 11A & B ) . T hey a r e g o l d t o t a n brown, a n d f i b r o u s . Rough h o r i z o n t a l l a m i n a e a r e f o r m e d by t h e accumu-l a t i o n o f C a r e x , J u n c u s , and S c i r p u s stems and o c c a s i o n a l b ands of c h a r c o a l . Culms o f t h e s e s e d g e s as w e l l as Typha and C a l a m o g r o s t i s c u t v e r t i c a l l y t h r o u g h t h i s l a y e r e d f a b r i c ( F i g . 1 1 C ) . Y e l l o w and b l a c k r o o t l e t s a r e p e r v a s i v e . A l -t h o u g h m a t e r i a l i s b e t t e r p r e s e r v e d t h a n i n s e d g e - c l a y p e a t s , a b u n d a n t amorphous m a t r i x a t t e s t s t o t h e h i g h d e g r e e o f de-c o m p o s i t i o n . W i t h t h e c o l o n i s a t i o n o f Sphagnum s p p . , e r i c a c e o u s s h r u b s r e p l a c e s e d g e - g r a s s c o m p o n e n t s . T h i s t r a n s i t i o n o c c u r s t h r o u g h a d i s t i n c t sedge-Sphagnum p e a t . The a d d i t i o n o f s m a l l q u a n t i t i e s o f Ledum and O x y c o c c u s stem and r o o t t i s -s u e s between Sphagnum p o c k e t s p r o d u c e s a r e d -brown c o l o u r e d p e a t w i t h w e l l d e v e l o p e d b e d d i n g . R h y n c h o s p o r a and E r i o p h o r u m c u l m s a r e v e r t i c a l l y o r i e n t e d and c u t o b l i q u e l y a c r o s s t h i s s t r a t i f i c a t i o n . Due t o t h e p r e s e n c e o f Sphagnum, most t i s s u e s , i n c l u d i n g some O x y c o c c u s and Ledum l e a v e s , a r e w e l l p r e s e r v e d . E r i c a c e o u s and p u r e Sphagnum p e a t s r e p r e s e n t c l i m a x b i o -f a c i e s ( F i g . 1 2 A ) . V a c c i n i u m , K a l m i a , and Ledum l e a v e s , 32 F i g u r e 11A. The modern, b r a c k i s h s e d g e - g r a s s marsh d e v e l o p e d between t h e two arms o f t h e F r a s e r R i v e r on L u l u I s l a n d . F i g u r e 11B. A p e a t s e c t i o n a t L u l u I s l a n d , a t t h e b a s e o f t h e s c a l e (30 cm), t h e b o u n d a r y between Sphagnum and s e d g e - g r a s s b i o f a c i e s i s v i s i b l e . F i g u r e 11C. A c l o s e - u p o f t h e f i b r o u s t e x t u r e o f s e d g e - g r a s s p e a t s , t h i s p e a t r e p r e s e n t s o r g a n i c a c c u m u l a t i o n s f r o m e n v i r o n m e n t s shown i n F i g u r e 11A. 34 F i g u r e 12A. E r i c a c e o u s Sphagnum community, showing new g r o w t h of P i n u s c o n t o r t a r e s u l t i n g f r o m r e c e n t d r a i n a g e , l a r g e s t P i n u s a r e between 5 and 6 m t a l l . P t e r i d i u m and Ledum a r e g r o w i n g between t h e P i n u s s t a n d s . F i g u r e 12B. E r i c a c e o u s Sphagnum p e a t w i t h t h e d i s t i n g u i s h i n g f i n e f i b r o u s t e x t u r e and f l a t t e n e d stems o f Ledum ( L ) . b l o c k i s a p p r o x i m a t e l y 15 cm w i d e . F i g u r e 12C. E r o s i o n o f t h e p e a t a l o n g t h e s o u t h e r n m a r g i n o f t h e L u l u I s l a n d d e p o s i t r e v e a l s a P i n u s stump i n sedge-wood p e a t , u n i t s o f s i l t y c l a y f r o m e a r l i e r o v e r b a n k d e p o s i t s (0) a r e i n t e r c a l a t e d w i t h t h i s p e a t as w e l l . 36' roots, and stems contribute s i g n i f i c a n t amounts of l i g n i n to a matrix of Sphagnum (Fig. 1 2 b ) . As a result of concentra-tions of these tissues, colours vary from gold for pure Sphagnum peat to dark brown for pure ericaceous peat. Tex-tures vary accordingly, from fibrous to granular. Charcoal fragments form discontinuous bands more frequently in the ericaceous Sphagnum biofa c i e s , and are often c l o s e l y asso-ciated with ericaceous layers. Bedding i s consequently well developed. The presence of Sphagnum assures good preserva-tion except near charcoal horizons. Nuphar-hollow peats result from the accumulation of de-t r i t a l plant material, p r i m a r i l y Pinus and ericaceous t i s -sues, in w a t e r - f i l l e d depressions. The growth and decomposi-tion of Sphagnum, Nuphar, and liverworts within these pools adds to the complexity of the r e s u l t i n g peats. Degradation is almost complete for most t i s s u e s . The remainder are sus-pended in the r e s u l t i n g amorphous orange matrix. A poorly developed microbedding exists from the presence of large l i v -erwort t h a l l i . Sedge-wood peats develop on the flanks of natural l e -vees. These peats consist of allochthonous Betula stems i n -terbedded with sedge peat. The matrix i s dark brown and f i -brous. Throughout t h i s well-bedded substrate are scattered large Picea and Populus stumps in growth position (Fig. 12C). Smaller stumps of Pinus replace these genera abruptly as Sphagnum bi o f a c i e s are approached away from the levee. Pre-.37 servation of l i g n i f i e d tissues i s good. This fac i e s i s con-fined to an area where the Fraser River i s presently eroding peat. The presence of stumps i s hard to detect using cores, and as a r e s u l t sedge-wood peats are probably more extensive than i s indicated here. d. Stratigraphy E a r l i e s t sedge-clay and sedge-grass peats grade downward to underlying grey s i l t y clay and clay over short distances. These peats i n t e r c a l a t e with thin, but l a t e r a l l y extensive, crevasse deposits of s i l t and s i l t y clay, and are broken by small channels of dominantly s i l t and s i l t y sand. These channels have p o s i t i v e r e l i e f , and thus reduce peat thickness (Figs. 8-10). Interlaminated clay and s i l t y clay of overbank or i g i n underly these peats for several tens of meters l a t e r -a l l y , along both sides of the channels. More recent fresh-water sedge-grass peats are void of sediment and are horizon-t a l l y s t r a t i f i e d above these small channel f i l l deposits. Along northern and eastern margins of the peat deposit, how-ever, where sedge-grass facies have prograded v e r t i c a l l y near larger channel f i l l deposits, splays do occur (Figs..9 and 10). These units are composed of medium to fine sand, and thin rapidly into the peat. Sedge-grass facies are horizon-t a l l y s t r a t i f i e d along the western edge.of the bog. Here, Sphagnum b i o f a c i e s abruptly o v e r l i e both levee and channel f i l l deposits. Splay deposits are absent from t h i s section of the peat. To the south, the main arm of the Fraser River 33 i s presently eroding thick accumulations of peat. e. Clay Minerals and Geochemistry Clay minerals in Lulu Island sediments (Table 1) are characterized by the abundance of k a o l i n i t e , i l l i t e , and smectite. Vermiculite and c h l o r i t e are present in minor amounts. No s i g n i f i c a n t gradation in abundance was observed except in a mixed layer of smectite-chlorite, which increased from trace amounts in freshwater sediments to small amounts in marine and brackish influenced sediments. Three cores were analysed for pH, t o t a l sulphur, and dry ash. Two of these cores, LIE 1 and LIE 2 (Figs. 13 and 14), were c o l l e c t e d from undisturbed bog environments. The t h i r d , LIE 3 (Fig. 15), was sampled from an eroded peat face which was exposed to the atmosphere at low tide and covered with r i v e r water during high t i d e . It i s overlain with clay, s i l t , and s i l t y sand from recent flood events. Sulphur compositions for Lulu Island sedge-Sphagnum and Sphagnum peats are similar to those obtained from comparable peats at P i t t Meadows described l a t e r . Values range from 0.15 to 0.23% and show no increase with depth. Ericaceous Sphagnum peats have s l i g h t l y higher sulphur values. Sulphur content for sedge-grass peats in core LIE 3 average 0.6%, and show l i t t l e v a r i a t i o n . Sulphur, however, increases markedly with depth, a t t a i n i n g values of between 3.0 and 6.0% near the 39 bottom of cores LIE 1 and LIE 2, corresponding to the occur-rence of brackish peat. Nuphar hollows contain s l i g h t l y higher concentrations of sulphur than surrounding Sphagnum b i o f a c i e s . The amount of ash in Sphagnum peats i s low, ranging from 0.5 to T.5%. L i t t l e v a r i a t i o n in the amount of ash occurs in v e r t i c a l section u n t i l sedge-grass peats are reached. Then, ash values reach 4%. Exceptionally large amounts of ash occur where either crevasse or f i r e splays have interrupted peat growth. In the.peat section of LIE 3 the average con-centration of ash is 7.5%. Sedge-clay t r a n s i t i o n zones con-tain up to 48% ash. Average pH values for LIE 1 and LIE 2 range from 3.5 for Sphagnum peat to 4.0 for freshwater sedge-grass peats. Char-coal horizons have higher pH readings. At depths c o r r e c t -able with the r i s e in sulphur concentration, pH values de-c l i n e to near 3.0 in these cores. PH measurements from core LIE 3 are more alk a l i n e and do not become more a c i d i c at depth, which i s l i k e l y a r e s u l t of invasion and contamination by river water at the eroded peat surface. Depositional History Sedge-grass peats began accumulating above i n t e r d i s t r i -butary s i l t y clays and clays of the lower delta p l a i n en-vironment 4685 years B.P. (Teledyne 1-11-742, 1981). As a LIE 1 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 • 1.6 1.S 2.0 2.2 2.4 2.0 2.8 3.0 3.2 3.4 3.8 o o • -o o o 0 0 o ° 0 * 0 o o o ° r i _• -* * _ MACROSCOPIC CONSTITUENTS PUfldtum rhliomaa Laduffl atama and root* Omcoceua rvnnara C0CCMI !••»•§ un roots " Pi-- l a a i - EJmu •••«!• - largo black aaod - Laduffl atama ind root* - Hhyncwoapora and Juneaa Juncaa and ,C«ra« eutmt - gplraa atom ? - Holuli atam Iragmant - M t u k Of Akim wood fragmanl - T»prn 1 atam - Typhi entm - TraM PH 3.0 4.0 6.0 8.0 1 f I I • % TOTAL SULPHUR 0 2.0 4.0 8.0 A % DRY ASH 0 5 10 15 20 Fig. 13. Peat p r o f i l e from Lulu Island showing peat types, macroscopic plant constitiuents and analysis of pH, sulphur and dry ash. High ash values at a depth of 2.5 m r e s u l t from incorporation of splay sediment into the peat. 41 MACROSCOPIC LIE 2 CONSTITUENTS 0 0.2 0.4 o.e 0.8 1.0 1.2 1.4 1.8 1.8 3 2-° i— 2.2 H Q_ 111 Q 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 o o o o o o o •.v;;e o o o • t ° O o o o o D O o o » o « M M PH 3 .0 4 .0 5 .0 6 . 0 - L t d u m and V a c c i n i u m starns a n d r o o t s ~ Be lu la a tarn 7 - O K y c o c c u i runnara - Rhynchotpora atom - C a r a t culm F*n"S r o e | ~~ large b lack s e e d s "~ L a d o m s l a m s - P inus n e e d l a s - O a y c o c c u s l e a v e s - l e O D e cu lms - teres o range C a r e x s e e d s - l iverwort thall i - Nuphar r o o t s 7 L e d u m a n d 0 » y c o c c u s l e a v e s Pinus roo t , need le L e d u m s t e m , root P inus root Betu la s tem f ragment Be tu la s t e m f ragments J u n c a a cu lm - C a r e * c u l m s - T r l g l o c h l n rh izome 7 \ % TOTAL SULPHUR 2.0 4.0 6.0 % DRY ASH 0 6 10 16 20 \ \ Fig. 14. Peat p r o f i l e from Lulu Island showing peat types, macroscopic plant constituents and a n a l y s i s of pH, sulphur and dry ash. Note large increases i n amount of sulphur at a depth of 3 m. a. a L E 3 0.2 -0.4 -0.6 -E 0.8-?= 1.0 -j 1.2-I 1.4 1.6 1.8 2.0 J It X MACROSCOPIC CONSTITUENTS - b totur tMlkm - Ladum ata«i»a, 8ph*ffiQum - Batuto bar* and root B«tu>a atama. branches 8p»»a at am Cif«» Typha cuan ' Oxycoccua runnar - Patula, atama • Splraa ? atama PH 3.o 4.0 5.o e;o 1 1 1 1 1 1 t 1 1 \ p 1 * 1 1 e i i i t k • 1 \ \ • % TOTAL SULPHUR 0 2.0 4.0 6.0 K % DRY ASH 0 5 10 15 20 •88 • 83 28 - 48 Fig. 15. Peat p r o f i l e from Lulu Island showing peat types, macroscopic plant constituents and analysis of pH, sulphur and dry ash. High ash values near the surface of t h i s core r e s u l t from recent overbank deposits. 43 result of a network of intervening channels, early peats were discontinuous and contained numerous fine grained splay de-pos i t s . The gradual abandonment of these small channels oc-curred as major d i s t r i b u t a r i e s became established. Isolated peat-forming marshes then coalesced, producing continuous peat horizons. The formation of both levees along major channels and an a c i d i c environment within the marsh limited the extent of c l a s t i c material entering into later peat fa-c i e s . Because of the influence of marine and brackish water, the t r a n s i t i o n from sedge-grass to Sphagnum biofacies oc-curred only after the substrate had been raised s u b s t a n t i a l l y by brackish sedge-peat accumulation. Along northern and eastern boundaries of the deposit, however, sedge-grass peats have not been replaced by Sphagnum b i o f a c i e s , but have pro-graded v e r t i c a l l y in response to continual f l u v i a l a c t i v i t y . Sphagnum peats are thin in these areas as a r e s u l t . A thick mantle of s i l t y clay over coarser channel f i l l sediments fur-ther suggests that the channel remained active at least during flood periods u n t i l very recently. The channel on the western margin appears to have been abandoned sooner, about 3000 years B.P. (Teledyne 1-11-743, 1981). Here Sphagnum peats have prograded over old channel f i l l deposits with sharp contacts. The growth of the south arm of the present Fraser River was coincident with the abandonment of the major channel to 44 the north and east of the deposit. In recent years t h i s channel has meandered slowly northward, cutt i n g through pre-viously deposited overbank and peat horizons and replacing them to the south with coarse grained channel f i l l deposits. P i t t Meadows a. Location and History The P i t t Meadows peat deposit i s situated on the Fraser River a l l u v i a l p l a i n , east of the confluence of the P i t t and Fraser Rivers (Fig. 1). Several other peat bogs have devel-oped within t h i s a l l u v i a l p l a i n to the north along the Alouette River and to the east along the Fraser River. Most are r e l a t i v e l y small peat accumulations, confined by flood pl a i n sediments. However, a large freshwater marsh has de-veloped south of P i t t Lake, where d e l t a i c lake sediments gradually have been reclaimed by sedge and grass communities. A l a t e r a l b i o f a c i e s zonation can be traced to the south in th i s deposit when the peat thickens. Climax communities sim-i l a r to those in other raised bogs o v e r l i e areas of maximum peat thickness. A radiocarbon date of 1860±80 B.P. (WAT 651) has been obtained from the base of t h i s peat at a depth of 140-145 cm (Lyngberg, 1979). Previous s c i e n t i f i c study of the P i t t Meadows peat de-posit is l i m i t e d to a single p r o f i l e reconstruction by Rigg and Richardson (1938). Mining of Sphagnum peat from this bog 45 occurred as early as 1920. When mining was f i n a l l y abandoned around 1960, up to 80 cm had been cut off c e r t a i n areas (C. Bacus, personal communication, 1980). Many areas along the margins have been reclaimed for a g r i c u l t u r a l use, primarily as blueberry and cranberry farms. b. L i t h o f a c i e s The P i t t Meadows peat deposit has accumulated within the Fraser River a l l u v i a l p l a i n . F l u v i a l l i t h o f a c i e s of similar origin but of d i f f e r e n t ages have interacted to produce a complex peat-forming environment. From a i r photo interpretation and 150 H i l l e r cores, rem-nants of old f l u v i a l channels can be recognized surrounding much of the deposit (Fig. 16). To the north and east, thick accumulations of grey s i l t and s i l t y clay cover f i n i n g upward sequences of fine to medium sand. These deposits grade l a t -e r a l l y into inter laminated s i l t s and clays which thin away from channels and are eventually replaced by massive grey clay and l e n t i c u l a r units of dark brown organic c l a y . The boundary between clay and overlying gyttja and sedge-grass peat is gradational over short distances (Fig. 20). In contrast, channel f i l l deposits on the west are cov-ered by a t h i n layer of s i l t which grades over short d i s -tances into underlying well-sorted medium and coarse sands. Along th i s western margin, interlaminated fine-grained sedi-- ALLUVIAL PLAIN CLAY Fig. 16. L i t h o f a c i e s map of the P i t t Meadows deposit. Dashed lines show l i n e a r channel features v i s i b l e from a e r i a l photographs. 47 merits are discontinuous and abruptly terminated by coarser c l a s t i c units (Fig. 18). To the south, l a t e s t levee sedi-ments consist of interlaminated s i l t y clay, peat, and a l l o c h -thonous wood fragments, which grade at depth to clay and s i l t y clay ( F i g . 20). Several smaller channels are recognized from cross sec-tions (Figs. 18, 19, and 20) and the isopach map (Fig. 17), where peat thickness increases along d i s t i n c t l i n e a r bands. These depressions are f i l l e d by sharply bounded units of either sedge-clay, gyttja, and sedge peat, or highly organic fining-upward cycles of fine sand, s i l t , and cl a y . Thin, a r e a l l y r e s t r i c t e d beds of fine sand and s i l t are confined to the e a r l i e s t stages of peat development, where they form sharp contacts with both peat and surrounding sedi-ment. Although in some places i n t e r n a l l y graded, they are more commonly massive. Coarse sediments grade l a t e r a l l y to clay away from charcoal-rich levees. Roots are pervasive throughout these splays where they occur in peat. c. Biofacies Apart from the absence of Nuphar peats and the presence of g y t t j a , P i t t Meadows b i o f a c i e s are similar to those a l r e a -dy described for the Lulu Island bog. Sedge-grass peats of P i t t Meadows, however, or i g i n a t e e n t i r e l y from freshwater rather than brackish marshes. As a result ericaceous shrubs PITT MEADOWS Fig. 17. Isopach map of the P i t t Meadows deposit. Darker areas show increased peat thickness as a r e s u l t of i n f i l l i n g of former avulsed channels. Fig. 18. Cross-sections A-A', B-B' from the P i t t Meadows deposit. Mote avulsed channel (c) in cr o s s - s e c t i o n B-B' increases.peat thickness, whereas a more recent l a r g e r channel has truncated the t h i c k e s t peats at both A and B. Fig. 17. shows the l o c a t i o n of cros s - s e c t i o n s . Legend i s i n Fig. 3. Fig. 19. Cross-sections C-C, D-D1 from the P i t t Meadows deposit. Small f l o o d channels (c) are more evident i n these two cros s - s e c t i o n s . F i g . 17. shows l o c a t i o n of c r o s s - s e c t i o n s . Legend i s i n F i g . 3. Fig. 20. Cross-section E-E 1, F-F' from the P i t t Meadows deposit. On both cross-s e c t i o n s , at E' and F' , i n t e r l a m i n a t i o n of peat and overbank s i l t y clay form the natural levee f a c i e s . F i g . 17. show l o c a t i o n of cross-sections. Legend i s in F i g . 3. 52 l i k e Ledum and Spirea contribute higher concentrations of woody tissue to sedge-grass peats. Ledum continues this trend in the lower portions of Sphagnum peat. The sedge-wood facies , which is exposed along the Fraser River at Lulu Island, was not recognized at P i t t Meadows, but should be extensively developed around much of the bog perimeter. Gyttja peat, which i s a red-brown to black organic muck, overlies clay or sedge-clay in l e n t i c u l a r beds. This b i o f a -cies represents the accumulation of plant debris in shallow pools p r i o r to sedge-grass peat development. Consequently, material i s so highly degraded that diatoms and d e t r i t a l wood and bark fragments are the only components recognizable in microtome section. d. Stratigraphy C y c l i c units of f i n i n g upward s i l t , s i l t y clay, and clay underly much of the peat deposit. Thin lenses of brown or-ganic clay intercalate with these sediments, forming d i s t i n c t but gradational contacts. To the north these l i t h o l o g i e s are t r a n s i t i o n a l to f i n e l y interlaminated clay and s i l t y clay. Within both l i t h o f a c i e s are sharply bounded troughs f i l l e d with either organic r i c h , s i l t y sands or sedge-clay, gyttja, and sedge-grass peats (Figs. 18 and 1 9 ) . Both channel f i l l deposits grade into overlying sedge-grass and Sphagnum peats, increasing peat thickness in long l i n e a r bands. With the exception of gyttja, which f i l l s small depressions beneath 53 s e d g e - g r a s s p e a t s , l a t e r b i o f a c i e s a r e g e n e r a l l y h o r i z o n t a l l y s t r a t i f i e d a n d of n e a r l y c o n s t a n t t h i c k n e s s . S e d g e - g r a s s and Sphagnum p e a t s p r o g r a d e o v e r u n d e r l y i n g l i t h o f a c i e s a l o n g n o r t h e r n and e a s t e r n m a r g i n s o f t h e d e p o s -i t . H e r e , s u r f a c e p e a t s form s h a r p , n e a r l y v e r t i c a l c o n t a c t s w i t h t h i c k m a n t l e s of g r e y , s i l t y c l a y w h i c h o v e r l y c o a r s e r c h a n n e l f i l l s e d i m e n t s . To t h e we s t , p e a t i n t e r c a l a t e s w i t h s i m i l a r l i t h o f a c i e s o v e r s h o r t d i s t a n c e s . In some a r e a s , however, t h e s e f i n e - g r a i n e d l i t h o l o g i e s a r e r e p l a c e d n e a r t h e s u r f a c e by b e d s of w e l l s o r t e d medium t o f i n e s a n d w h i c h c o a r s e n s h a r p l y downward. D e p o s i t i o n of t h e s e c h a n n e l f i l l u n i t s i s i r r e g u l a r . I n t h e s o u t h , l i k e t h e w e s t , p e a t s and f l u v i a l s i l t y c l a y s a r e i n t e r c a l a t e d . The zone o f i n t e r c a l a -t i o n , however," i s l a t e r a l l y e x t e n s i v e , and p r o g r a d e s v e r t i -c a l l y t o w a r d t h e p r e s e n t c h a n n e l p o s i t i o n . Much a l l o c h -t h o n o u s woody d e b r i s h a s been i n c o r p o r a t e d i n t o t h e s e s e d i -ments. I n a s i m i l a r manner, s e d g e - g r a s s p e a t s p r o g r a d e v e r -t i c a l l y n e a r t h e c h a n n e l m a r g i n . e. C l a y M i n e r a l o g y and G e o c h e m i s t r y A n a l y s i s o f P i t t Meadows u n d e r c l a y and n a t u r a l l e v e e d e p o s i t s r e v e a l s t h a t k a o l i n i t e c o m p r i s e s a p p r o x i m a t e l y 60% of t h e c l a y m i n e r a l s p r e s e n t ( T a b l e 2 ) . I l l i t e and s m e c t i t e c o m p r i s e much o f t h e r e m a i n d e r , b ut s m a l l amounts of b o t h v e r m i c u l i t e and c h l o r i t e a r e a l s o p r e s e n t . O n l y t r a c e amounts o f m i x e d l a y e r s m e c t i t e - c h l o r i t e a r e o b s e r v e d . Near 5 4 the top of natural levee sediments the percentage of kao-l i n i t e increases at the expense of i l l i t e . Three cores were obtained for geochemical analysis and petrographic study. Two of these cores, PM 1 and PM 2 (Figs. 23 and 24), were c o l l e c t e d from peat-forming environ-ments, while the t h i r d , PM 3 (Fig. 25), was obtained from a natural levee. Several centimeters of Sphagnum peat have been removed by mining from the top of core PM 1. The re-maining upper section of t h i s peat has also been desiccated for extended periods of time because of di t c h i n g . PM 2, how-ever, is from an undisturbed area of the bog, and represents a natural peat section. Sulphur concentrations are less than 0.5% for a l l of these cores, and show only a s l i g h t increase with depth. In cores PM 1 and PM 2, ash content varies from 0.5 to 1.5% in Sphagnum peats and from 1.0 to 3.0% in sedge-grass peats. Concentrations up to 7.0% are recorded in charcoal horizons within highly ericaceous Sphagnum peat. Near the base of the deposit ash values of between 25.0 and 75.0% occur in t r a n s i t i o n a l sedge-clay peats. Where peat has prograded over natural levee s i l t y clay in PM 3, ash contents average 5.0%. Values increase to be-tween 33.0 and 68.0% for the f i n e l y interlaminated peat and s i l t y clay beneath these zones. MACROSCOPIC CONSTITUENTS pH 3.0 4.0 5.0 6.0 Ledum branches lern rhizomes / 4 i Rhynchoipora stems Betula branches T i Ledum roots and branches • t | Oxycoccus runners Pinus root Kalmla root Vacclnium stems f i Rhynchojpora stems Oxycoccus runners Carex culm • \ ». X \ \ Typha culm ? red brown seeds Splrea stem and root Equlsetum rhizomes Carex culm 1 \ \ % TOTAL SULPHUR 0 2.0 4.0 6.0 % DRY ASH 0 5 10 15 / I i * Fig. 21. Peat p r o f i l e from P i t t Meadows, showing peat types, macroscopic plant constituents and analysis of pH, sulphur and dry ash. Unlike Lulu Island, pH values become more a l k a l i n e with depth and sulphur remains constant. PM 2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 o o o o o 1,0 * A A A A A MACROSCOPIC CONSTITUENTS - Ledum stems and roots - Oxycoccus leaves - Plnus root Carex culm Rhynchoipora stem Ledum sterna and roots Oxycoccus runners Ledum sTem3 and leaves Oxycoccus leaves Carex and Rhynchoipora culms Oxycoccus runners and leaves' Rhynchoipora stems dum stem PH 3.0 4.0 5.0 6.0 s and roots - Carex - Splrea ? stems - Carex. Juncas. stems - Equlsatum rhizomes - Splrea ? stems Equlaetum  Splrea ? stems • % TOTAL SULPHUR 0 2.0 4.0 6.0 % DRY ASH 5 10 15 20 1 > / f » 1 \ • • 1 1 6 I \ > f T i Fin. 22. Peat p r o f i l e from P i t t Meadows, showing peat types, macroscopic plant constituents and analysis of pH, sulphur and dry ash. PM 3 0 0.2 0.4 E °-6 r«~»v L i X r-fX LU o.e - r 1.0 1.2 -t 1.4 1.6 MACROSCOPIC CONSTITUENTS lern rhizome ( Pterldlum ap?) P H 3.0 4.0 5.0 6.0 grass stems Equlaelum rhizomes T i I i T T I I • % TOTAL SULPHUR 0 2.0 4.0 6.0 T i i i T % DRY ASH 0 5 10 15 2 0 -33 -42 -38 -44 - 36 - 68 - 63 Fig. 23. Peat p r o f i l e from P i t t Meadows, showing peat types, macroscopic plant costituents and analysis of pH, sulphur and dry ash. This p r o f i l e represents the natural levee, and therefore ash contents are very high as a r e s u l t of i n t e r c a l a t e d overbank deposits. 58 pH measurements from each of the P i t t Meadows cores show decreased a c i d i t y with depth (Figs. 21-23), with values ap-proaching 5.0. Minor increases in pH throughout the three cores occur in charcoal horizons. Depositional History Peats near P i t t Meadows i n i t i a l l y accumulated in shallow depressions and small flood channels within the extensive a l l u v i a l p l a i n of the Fraser River. The growth of these early peats was l i k e l y coincident with a declining rate of eustatic sea l e v e l r i s e . At t h i s time, channels which appear to have been active in the north gradually began i n f i l l i n g with fine sand and s i l t , and were replaced to the. south by the present channel of the Fraser River. After establishment of t h i s channel, flooding occurred less frequently, thus a l -lowing previously confined peat lenses to spread l a t e r a l l y over the flood p l a i n . Sphagnum colonized the freshwater sedge-grass marshes soon after t h i s event. The highly a c i d i c conditions produced by Sphagnum resulted in f l o c c u l a t i o n of clay minerals at bog boundaries and increased peat accumulation through reduced decomposition. F l u v i a l a c t i v i t y was thus further r e s t r i c t e d , which allowed l a t e r peat bi o f a c i e s to succeed e a r l i e r sedge-grass peats and expand the bog environment l a t e r a l l y . Peats prograded over flood sediments on inactive boundaries and intercalated with deposits on active margins. Limited mean-59. dering by the present channel has eroded natural levee and peat facies on the western boundary and replaced them with coarse c l a s t i c channel f i l l deposits. DISCUSSION AND CONCLUSION Lit h o f a c i e s and Depositional Sett ing Peats began accumulating in quiet facies of several d i f -ferent environments of the Fraser River delta between 4,300 and 4,800 B.P. (Luternauer and Murray, 1973; Hebda, 1977; Teledyne #1-11 742, 1981). At present, peat deposits extend over approximately one t h i r d of the delta surface. Although s i m i l a r i t i e s exist between i n d i v i d u a l deposits, l i t h o f a c i e s exhibit differences r e s u l t i n g from unique depositional set-tings developed within the d e l t a . Boundary Bay peats have accumulated on an inactive por-tion of the lower delta p l a i n , marginal to the delta front. Unlike the peats of P i t t Meadows and Lulu Island, those of Boundary Bay were not influenced to any great extent by f l u -v i a l a c t i v i t y . Rather, they developed from s a l t and brackish marshes on the broad expanse of inactive t i d a l f l a t s . Coleman and Smith (1964) have used the term 'blanket peats' for these extensive but thin and discontinuous units. Sedi-ment compaction and the rate of eustatic sea l e v e l r i s e con-t r o l the margins of i n d i v i d u a l peat horizons. In areas where peat accumulation exceeds sea l e v e l r i s e , peats coalesce into larger 'peat islands' (Staub and Cohen, 1979) dominated by 60 glycophyte communities. Otherwise, peat development is re-s t r i c t e d or terminated by transgressive marine sediments. Addition of sulphur, increased degradation, and p a r t i a l ero-sion may occur prior to b u r i a l . Thin in t e r c a l a t e d units of s i l t and s i l t y clay occur throughout the peat section at Boundary Bay as a result of the complex interaction of spring freshets, storms, and ti d e s . The occurrence of these washover deposits increases toward the base of the peat, where i t grades into underlying fine f l u v i a l sediments or coarse delta front s i l t y sand. Both of these units o v e r l i e an extremely thick sequence of coarsening upward prodelta s i l t y clay and clay (Blunden, 1973), ( F i g . 24). Both Lulu Island and P i t t Meadow peats have formed in fluvially-dominated environments (Figs. 25 and 26 and Table 1). E a r l i e s t peats of these deposits o v e r l i e f i n i n g upward sequences of s i l t y sand, s i l t , and s i l t y c l a y, and are con-fined l a t e r a l l y by channel f i l l sands and s i l t s . Thin splay units comprised of fine sand, s i l t , and clay i n t e r c a l a t e near the base of the peats, though less commonly than at Boundary Bay. Lulu Island sedge-grass peats are d i f f e r e n t , however, from those of P i t t Meadows, having accumulated under the i n -fluence of brackish water and t i d a l a c t i v i t y in an environ-ment t r a n s i t i o n a l between upper and lower delta p l a i n s . As a re s u l t , peats deposited i n i t i a l l y between d i s t r i b u t a r y chan-nels at Lulu Island are more degraded and contain higher con-TABLE 1: SUMMARY OF DEPOSITIONAL PARAMETERS Boundary Bay L u l u I s l a n d P i t t Meadows D e l t a Front-Lower D e l t a P l a i n Lower D e l t a P1 a 1n-Upper De1ta P l a i n Upper D e l t a P1 a 1n-A 11uv1 a 1 P l a i n Depos1t1onal S e t t I n g : L 1 t h o f a c l e s : t h i n f i n i n g upward sequence over t h i c k c o a r s e n i n g upward p r o d e l t a sediments i n t e r d i s t r i b u t a r y c l a y s beach sands channel f i l l s i l t s t h i c k f i n i n g upward c y c l e over major c o a r s e n i n g upward p r o d e l t a sediments i n t e r d i s t r i b u t a r y c l a y s n a t u r a l l e v e e s i l t y c l a y s channel f i l l s a n d s , s i l t s , c r e v a s s e s p l a y s f i r e s p l a y s s e v e r a l small f i n i n g upward c y c l e s i n a major f i n i n g upward sequence i n t e r d i s t r i b u t a r y c l a y s n a t u r a l l e v e e s i l t y c l a y s channel f i l l sands, s i l t s c r e v a s s e s p l a y s B i o f a c i e s : sedge-grass ( f r e s h ) s edge-grass ( b r a c k i s h ) sedge-grass (marine) s e d g e - c l a y Peat T h i c k n e s s . l a t e r a l l y e x t e n s i v e and e x t e n t : t h i n and i r r e g u l a r Peat Qua 11ty: Su1phur: Ash: C l a y M i n e r a 1 s : h i g h , p e r v a s i v e h i g h , p e r v a s i v e storms - t i d e s wash over d e p o s i t s mixed l a y e r c h l o r 1te-smect1te common k a o l i n i t e / s m e c t i t e r a t i o lower sphagnum nuphar hoi 1ow (sedge-wood) sedge-sphagnum sedge-grass ( f r e s h ) sedge-grass ( b r a c k i s h ) s e d g e - c l a y l a t e r a l l y e x t e n s i v e t h i c k but v a r i a b l e h i g h at base o n l y h i g h at base o n l y c r e v a s s e s p l a y s f1oods mixed l a y e r c h l o r 1 t e - s m e c t i t e at base o n l y k a o l i n i t e / s m e c t i t e r a t i o h i g h e r sphagnum sedge-sphagnum sedge- g r a s s ( f r e s h ) g y t t j a e sedge-c1 ay l a t e r a l l y r e s t r i c t i v e m o d e r a t e l y t h i c k - c o n s t a n t 1 ow low except near base f1oods no mixed l a y e r ch1 or 1 t e - s m e c t i t e k a o l i n i t e / s m e c t 1 t e r a t i o h i g h 62 centrations of both ash and sulphur than analagous freshwater peats at P i t t Meadows. Maximum peat thickness of over 4.0 m occurs in i n t e r d i s t r i b u t a r y regions of the Lulu Island depos-i t , where channels were abandoned e a r l i e s t (Fig. 25). In contrast, the thickest accumulation of P i t t Meadows peat occurs where avulsed flood channels have been f i l l e d with hypautochthonous plant material. Sphagnum dominated peat f a c i e s succeed e a r l i e r sedge-grass and sedge-Sphagnum peats in both the P i t t Meadows and Lulu Island deposits. Although of sim i l a r generic composi-tio n , peats in each deposit inter a c t d i f f e r e n t l y with the surrounding l i t h o f a c i e s . At Lulu Island, where channels were active throughout peat accumulation, overbank s i l t y clays intercalate with sedge peat and are disrupted by occasional splay events of sand and s i l t y sand. Such flood deposits are rare in P i t t Meadows peats as a result of well developed na-t u r a l levees along active channels (Fig. 26). Along inactive margins, sharp boundaries r e f l e c t the active progradation of Sphagnum l i t h o f a c i e s and the effectiveness of ac i d i c bog water in f l o c c u l a t i n g suspended clays (Staub and Cohen, 1978). Biofacies and Peat Stratigraphy The b i o f a c i e s of the Lulu Island, P i t t Meadows, and Boundary Bay deposits are rela t e d through a common succes-sional sequence. This sequence originates from either 250 m - M O m e3p o o o o LEGEND Peat Organic Clay Interdistributary Clay Overbank Silty Clay Channel Sand Delta Front Sand Prodelta Clay BOUNDARY BAY Fig. 24. Summary model of peat r e l a t i o n s h i p s with other l i t h o f a c i e s within the d i s t a l lower delta p l a i n environment. Fig. 25. Summary model of peat r e l a t i o n s h i p s with other l i t h o f a c i e s within the t r a n s i t i o n a l lower delta p l a i n -upper delta p l a i n environment. Legend f o r diagram Fig. 26. Summary model of peat r e l a t i o n s h i p s with other l i t h o f a c i e s within the upper delta p l a i n - a l l u v i a l p l a i n environment. Legend-, for diagram i s in Fig. 24. 66 pioneering marine or freshwater sedge grass communities, and culminates with a climax community dominated by Sphagnum, Ledum, and Pinus (Oswald, 1933). External disruptions can disrupt the sequence permanently, as the marine transgression has done to the sedge-grass communities at Boundary Bay, or they can cause temporary reversals, such as those r e s u l t i n g from f i r e s in the Sphagnum communities of both Lulu Island and P i t t Meadows. In a l l instances, sedge-grass communities i n i t i a t e the successional sequence by occupying wet disturbed niches and forming marshes. Species composition varies ac-cording to s a l i n i t y , substrate elevation, and pH (Envirocon, 1981). Any sediment i n f l u x i s trapped by the r i g i d network of stems and i s quickly s t a b i l i z e d by the extensive root sys-tem. Gradually the substrate i s b u i l t up s u f f i c i e n t l y to r e s i s t a l l intrusions of sediment-laden water, and a t r a n s i -tion to organic sedimentation occurs. Eventually peat ac-cumulation i s s u f f i c i e n t to change the regime from brackish to freshwater conditions and allow the colonization of Sphagnum spp. The growth of Sphagnum r e s t r i c t s water flow, reduces pH and l i m i t s nutrient supply. These conditions are unfavourable for the continued development of sedge-grass communities, and they are replaced by Pinus and ericaceous shrubs such as Ledum, Vacc inium, and Kalmia. Once th i s climax stage is reached, f i r e controls species composition and d i s t r i b u t i o n (Hebda, 1977). Although most peat f a c i e s are common to each deposit, variation in thickness, l a t e r a l extent, and geometry do 67 o c c u r . T h e s e d i f f e r e n c e s a r i s e a s a r e s u l t o f c h a n g e s i n c l i m a t e and s e d i m e n t a r y r e g i m e t h r o u g h o u t t h e d e l t a . At L u l u I s l a n d , due t o t h e i n f l u e n c e o f b r a c k i s h w a t e r , Sphagnum was u n a b l e t o c o l o n i z e e a r l y s e d g e - g r a s s p e a t s . As a r e s u l t , t h e t h i c k e s t a c c u m u l a t i o n s o f s e d g e - g r a s s p e a t were r e q u i r e d h e r e b e f o r e t h e s u b s t r a t e was r a i s e d s u f f i c i e n t l y t o a l l o w o t h e r b i o f a c i e s t o s u c c e e d . The c o n t i n u e d movement of t i d a l w a t e r t h r o u g h t h e e a r l y m a r s h e s may a l s o have r e s t r i c t -ed t h e d e v e l o p m e n t o f a g y t t j a b i o f a c i e s . The f r e s h w a t e r e n v i r o n m e n t o f t h e P i t t Meadows d e p o s i t n o t o n l y a l l o w e d t h e t r a n s i t i o n t o Sphagnum b i o f a c i e s t o o c c u r q u i c k l y n e a r t h e b a s e of t h e d e p o s i t , but a l s o a l l o w e d a d i s c o n t i n u o u s g y t t j a h o r i z o n t o d e v e l o p p r i o r t o c o n t i n u o u s s e d g e - g r a s s p e a t a c -c u m u l a t i o n . S e d g e - g r a s s p e a t s a r e t h i n as a r e s u l t . The v e r t i c a l m i g r a t i o n o f s e d g e - g r a s s b i o f a c i e s o c c u r s a l m o s t e x c l u s i v e l y a t t h e L u l u I s l a n d d e p o s i t . C o n t i n u a l f l u v i a l a c t i v i t y a l o n g d e p o s i t m a r g i n s t h r o u g h o u t p e a t a c -c u m u l a t i o n p r o d u c e s t h i s s i t u a t i o n . C o r r e s p o n d i n g l y , t h e o n l y m a r g i n a t P i t t Meadows where s e d g e - p e a t s have p r o g r a d e d v e r t i c a l l y i s t o t h e s o u t h . A l l o t h e r m a r g i n s a r e h o r i z o n -t a l l y s t r a t i f i e d , s i m i l a r t o t h e r e m a i n d e r o f t h e d e p o s i t . The a l l u v i a l p l a i n n e a r P i t t Meadows r e c e i v e s a p p r o x i -m a t e l y t w i c e t h e a v e r a g e r a i n f a l l a s t h e d e l t a p l a i n , where b o t h L u l u I s l a n d and B o u ndary Bay p e a t s a r e l o c a t e d . The p e a t s u r f a c e a t P i t t Meadows i s s e l d o m d e s i c c a t e d f o r ex-68 t e n d e d p e r i o d s o f t i m e , and i n c o m p a r i s o n , p e a t f a c i e s f r o m t h i s d e p o s i t a r e b e t t e r p r e s e r v e d , w i t h f e w e r o b s e r v a b l e f i r e h o r i z o n s , t h a n t h o s e p e a t s of t h e d e l t a p l a i n . Woody ma-t e r i a l a n d s e d g e c u l m s a r e a l s o more p e r v a s i v e i n Sphagnum and e r i c a c e o u s Sphagnum p e a t s . D u r i n g t h e summer, d e s i c c a -t i o n of t h e p e a t s u r f a c e a t t h e L u l u I s l a n d d e p o s i t i s s e v e r e enough t o a l l o w d e e p and l a t e r a l l y e x t e n s i v e b u r n i n g . " I n t h e w i n t e r months, a r e a s where d e e p b u r n i n g has o c c u r r e d f i l l w i t h w a t e r t o p r o d u c e Nuphar h o l l o w s ( O s w a l d , 1933). The d e p r e s s i o n s a c c u m u l a t e a l l o c h t h o n o u s p l a n t d e b r i s and f o r m u n u s u a l p e a t s , c h a r a c t e r i s t i c of t h e d e l t a p l a i n . A l t h o u g h t h e c o n f i n e m e n t of t h e sedge-wood b i o f a c i e s t o t h e L u l u I s l a n d d e p o s i t may be c a u s e d by t h e l i m i t e d e x p o s u r e of t h e s e p e a t s , i t may a l s o be r e l a t e d t o t h e d e g r e e o f n a -t u r a l l e v e e d e v e l o p m e n t . The l a r g e s u p p l y o f n u t r i e n t s ne-c e s s a r y t o s u p p o r t t h e l a r g e b i o m a s s o f t h i s community c o u l d o n l y be p r o v i d e d by o c c a s i o n a l f l o o d i n g . The p o o r l y d e v e l -oped n a t u r a l l e v e e s a t t h e L u l u I s l a n d d e p o s i t have a l l o w e d s m a l l amounts o f c l a y s and n u t r i e n t s i n t o t h i s f a c i e s . T h i s i s c o n f i r m e d by t h e h i g h a s h c o n t e n t o f t h e s e p e a t s ( F i g . 1 5 ) . P e a t s m a r g i n a l t o c h a n n e l s a t P i t t Meadows a r e low i n a s h ( F i g s . 21, 2 2 ) . A c o m b i n a t i o n o f w e l l d e v e l o p e d n a t u r a l l e v e e s and h i g h l y a c i d i c bog c o n d i t i o n s may have r e -s t r i c t e d t h e sedge-wood f a c i e s t o a n a r r o w band a l o n g t h e l e v e e . H e r e , c o n d i t i o n s were not f a v o u r a b l e f o r t h e p r e s e r -v a t i o n o f p l a n t m a t e r i a l . 69 Clay Mineralogy Only s m a l l v a r i a t i o n s of c l a y m i n e r a l composition occur w i t h i n bog l i t h o f a c i e s (Table 1 ) . K a o l i n i t e and i l l i t e are the dominant c l a y m i n e r a l s , c o m p r i s i n g between 75 and 85% of the t o t a l sample, while s m e c t i t e , v e r m i c u l i t e , and c h l o r i t e occur i n minor amounts. K a o l i n i t e i s e n r i c h e d i n samples a f f e c t e d by low pH con-d i t i o n s , i n c l u d i n g those from u n d e r c l a y , crevasse s p l a y and n a t u r a l levee l i t h o f a c i e s (Table 1). However, sediments from beneath marine i n f l u e n c e d peats (LIE P +C 5 ) , which have been a f f e c t e d by more n e u t r a l pH c o n d i t i o n s , have sma l l e r concen-t r a t i o n s of k a o l i n i t e . The v a r i a t i o n i n k a o l i n i t e content w i t h i n the n a t u r a l levee l i t h o f a c i e s (PM P 3C, , P3 and P3 Cfe ) can be a t t r i b u t e d to a response to pH c o n d i t i o n s ( F i g . 23). In those samples showing the l a r g e s t k a o l i n i t e c o n t e n t , there i s a c o r r e s p o n d i n g decrease i n s m e c t i t e . T h i s r e l a t i o n s h i p i s most prominent when c l a y m i n e r a l assemblages from peat-forming environments are compared to those r e p o r t e d from the F r a s e r R i v e r and S t r a i t of Georgia by Pharo (1972). A l -though of s i m i l a r provenance, these marine d e p o s i t e d c l a y s c o n t a i n 30% more s m e c t i t e and 40% l e s s k a o l i n i t e . Smectite must t h e r e f o r e be b r e a k i n g down under the h i g h l y a c i d i c con-d i t i o n s of the P i t t Meadows and L u l u I s l a n d bogs and forming k a o l i n i t e , as shown in the e q u a t i o n from Berner (1971): 4Na A l 1 5 Mg 0 5 S i ^ 0 1 0 (OH)4 m o n t m o r i l l o n i t e + 6H 2C0 3+19H 20 70 3A1£ S i 2 0 5 (OH) + (kaolinite) + 2Mg* 2 + 2Na+; 6HC03 " + 1 0H4SIC\ Staub and Cohen (1978) describe a similar transformation in the Snuggedy Swamp, South Carolina, and Huddle and Patterson (1961) and others have come to analogous conclusions from study of coal deposits. A mixed-layer smectite-chlorite occurs in brackish i n -fluenced clays and increases in abundance in marine i n f l u -enced sediments of Boundary Bay. This mixed-layer clay was noted by both Pharo (1972) and Mackintosh and Gardner (1966) in sediments c o l l e c t e d from the Fraser River. Although the formation of t h i s mixed-layered clay may be dependent on marine conditions, i t is l i k e l y that i t was also present in the peat-forming environment and i t too was converted to kao-l i n i t e . Geochemi stry Measurement of pH in the three peat forming environments supports e a r l i e r research by Staub and Cohen (1978, 1979) and others that near neutral to s l i g h t l y a l k a l i n e pH conditions are associated with marine influenced peats (Fig. 5), whereas freshwater environments, e s p e c i a l l y those which contain Sphagnum, exhibit pH values as low as 3.0. In P i t t Meadows cores these values become less a c i d i c in underlying fresh-water sedge-grass peats (Figs. 21-23). However, in cores from Lulu Island, t h i s trend stops and reverses i t s e l f once TABLE 2: CLAY MINERALOGY Samp 1e Env 1 ronnient 7 0 10" 10"-17 0 14° 14" Mixed Layer K a o l i n i t e I H I t e S m e c t i t e V e r m l c u l l t e C h l o r i t e Smect1te-Chlor 1te PM P, C, PM P, PM P, Ct LIE P 3 C, LIE P3 Cz LIE P 4C, LIE R,C5 BB P, f r e s h w a t e r under bog p r o p e r / o r g a n l c s f r e s h w a t e r under bog p r o p e r / o r g a n l c s f r e s h w a t e r n a t u r a l l e v e e bottom n a t u r a l l e v e e middle n a t u r a l l e v e e top f r e s h w a t e r c r e v a s s e s p l a y f r e s h w a t e r overbank c r e v a s s e c s e bog bottom top bra c k 1sh bog bottom middle brack 1sh bog bottom bottom mar 1ne bog bottom top mar 1ne bog bottom middle mar 1ne 51 58 61 63 69 49 46 overbank c r e v a s s e f i n e 58 bottom bog proper/no o r g a n l c s 56 f r e s h w a t e r b r a c k i s h BB P, C 3 bog bottom bottom AVERAGE PHARO (1972) 52 59 53 45 45 45 smal 1 31 21 27 28 19 36 29 25 27 28 27 30 43 30 4 1 38 13 10 4 2 9 19 12 12 15 12 16 10 40 unknown 4 22 t smal 1 smal 1 sma 1 1 abundant abundant abundant abundant not Iced F r a s e r R i v e r and S t r a i t of G e o r g i a 7.2 brackish water high sulphur peats are reached (Figs. 13-15). The pH decreases to values representative of Sphagnum peats in areas where sulphur concentration i s highest. It is sug-gested that H* ions, released when H aS undergoes further re-duction to form amorphous iron sulphide minerals, causes the increased a c i d i t y . Measurements of pH from the Boundary Bay core, BB1 (Fig. 5) show no v a r i a t i o n with depth. Total sulphur analysis from the various biofacies of the three peat deposits (Figs. 5, 13-15, 21-23 and Table 3), i n -dicate that the large differences in sulphur concentration observed are controlled by the environment of deposition. The association of high sulphur concentrations with marine environments is well documented (Williams and Keith, 1963). The reason for such a r e l a t i o n s h i p i s not only the high con-centration of dissolved SQ^ . 2" in marine water, but also ele-vated pH conditions which allow b a c t e r i a l reduction of the sulphate ion (Berner, 1971). Sulphur in marine peats i s also concentrated, often by two orders of magnitude above those of freshwater peats (Casagrande et. a l . , 1977), by the continual growth of p y r i t i c sulphur from b a c t e r i a l l y reduced H 2S. Both C e c i l e_t a l (1977), from studies of Apalachian coals, and Casagrande et a l . (1977), from studies of Okefenokee peats, suggest that pH i s the c o n t r o l l i n g parameter in t h i s process. Indeed, the a c i d i c conditions of freshwater peats (pH>4.5) decreases the a c t i v i t y of D e s u l f i v i b r i o spp. (Zobell, 1963), corresponding-73 ly reduces H ZS production, and lowers the concentration of sulphur incorporated into the peat (Casagrande et a_l. , 1980). Sulphur d i s t r i b u t i o n in Fraser delta peats r e f l e c t s these p r i n c i p l e s . Samples from marine influenced peats, core BB (Fig. 5) and brackish influenced peats, cores LIE 1 and LIE 2 (Figs. 13-14), which had' the less a c i d i c depositional en-vironments, have c h a r a c t e r i s t i c a l l y high sulphur concentra-tions. Correspondingly highly a c i d i c freshwater peat en-vironments, cores PM 1, PM 2, PM 3, and LIE 3 (Figs. 17-19 and 15), have small amounts of sulphur. In less a c i d i c en-vironments where pH does not control the amount of reduced sulphate, Berner (1971) suggests the amount of organic sub-strate a v a i l a b l e for b a c t e r i a l consumption may control the amount of p y r i t i c and thus t o t a l sulphur. This rel a t i o n s h i p may explain the decrease in t o t a l sulphur in sediments beneath the peat at Boundary Bay ( F i g . 5), where organic matter concentration i s much less than in the overlying peats. Small v a r i a t i o n s in sulphur with depth in freshwater peats of Lulu Island and P i t t Meadows can be attributed to differences in sulphur concentration in s p e c i f i c biofacies (Table 3). Sphagnum peats contain the smallest amount of sulphur, while sedge-wood peats contain the largest concen-t r a t i o n . Woody tissues and charcoal cause s l i g h t increases in sulphur content. F i r e s may simply concentrate sulphur in ash, but also the more alk a l i n e conditions associated with the f i r e horizons may promote reduction of S04 by bacteria. 74 Work by Casagrande e_t a l . (1980) suggests that much of the sulphur of freshwater peats i s organic, with a major fr a c t i o n occurring as ester sulphate. Amounts of p y r i t e and H 2S are correspondingly low. Complete sulphur analysis on these peats has not been completed to confirm these trends. Table 3. Sulphur Content in Peat Facies Peat Facies Percent Total Sulphur (Dry Weight) range average Pure Sphagnum 0. 1 2 - 0. 19 0. 1 6 Ericaceous Sphagnum 0. 1 5 - 0. 23 0. 1 9 Sedge-grass freshwater 0. 1 4 - 0. 77 0. 35 Sedge-grass brackish 0. 64 - 1 . 50 1 . 1 2 Sedge-grass marine 5. 3 - 6. 3 5. 9 Nuphar hollow 0. 21 - 0. 32 0. 27 Sedge-Sphagnum 0. 19 0. 19 Sedge-clay freshwater 0. 1 3 - 0. 1 6 0. 1 5 Sedge-clay marine 3. 3 - 5. 9 4. 3 Both the P i t t Meadows and Lulu Island freshwater peats contain small amounts of ash. Increased concentrations of ash appear to result from wood or charcoal in sedge-Sphagnum and ericaceous Sphagnum biofacies and also from crevasse splay s i l t y clays in sedge-grass b i o f a c i e s . Facies t r a n s i -t i o n a l to f l u v i a l sediments, the sedge-clay and gyttja peats, contain large q u a n t i t i e s of ash. The high concentration of ash in the marine derived and 75 influenced peats of Boundary Bay was caused by the occasional flooding of t h i s deposit during accumulation. Suspended clay and s i l t were deposited after inundations by some annual high tides, the Fraser River freshet, and/or extreme storms. The lower pH of the marsh environment may have assisted in the deposition by causing f l o c c u l a t i o n of clay materials (Staub and Cohen, 1978). High ash contents appear to be associated with high sulphur concentrations. C a l o r i f i c value depends both on the ash content and the plant composition of the peat (Fig. 27). Woody peats have the highest heating values, while Sphagnum peats produce the lowest. Sedge-grass peats vary widely between these b i o f a -c i e s , and because they contain variable amounts of mineral matter, they demonstrate the e f f e c t s of ash on heating v a l -ues. Sedge peats on an ash-free basis produce 22,000 KJ/kg (oven dr i e d ) , which i s comparable to 25,000 KJ/kg for sub-bituminous coal (Teichmuller and Teichmuller, 1966). Although Boundary Bay peats would produce the least energy based on the high ash content, i t i s d i f f i c u l t to say which of the other two deposits would produce the most ener-gy. The increased thickness of sedge peats at Lulu Island i s offset by the small amount of wood in t h i s deposit compared with P i t t Meadows. As well, the sedge-grass peats of Lulu Island contain more ash because of numerous crevasse splays. 76 50 -i 40 H 30 - p i s ^ ^ g I CO < -t->»»»:-:-:<-:-:<-^: 20 -i 1 0 - f L E G E N D • - S p h a g n u m , E r i c a c e o u s S p h a g n u m f a c i e s » - F i re z o n e s A - S e d g e - g r a s s f a c i e s • - W o o d y z o n e s 'i i v 10 12 mm 4 14 ~I r 16 18 8 22 i r 24 I 26 K J / K g x 1 0 ' Fig. 27. Percent ash versus c a l o r i f i c value p l o t f o r an a l y s i s of major peat b i o f a c i e s . 77 Fraser River Delta Peats as Coal Deposits Fraser River delta peats w i l l eventually transform into coal seams. Peats previously deposited on the d e l t a , 8900 years B.P., and which have been covered with up to 15 m of sediment have produced seams of peat up to 15 cm thick (J. Clague, personal communication, 1981). Considering a compac-tion r a t i o of approximately 10:1 for peat to subbituminous coal (Ryer and Langer, 1980), the present thickness of peats at Lulu Island could produce a coal seam 40 cm thick. The accumulation of peat at both P i t t Meadows and Lulu Island would c e r t a i n l y have continued, were i t not for the recent intervention of man. Each of the three peat-forming environments studied has produced deposits with a s i m i l a r successional sequence of plant communities. The e f f e c t s of the physical environment, however, have modified surrounding l i t h o f a c i e s , peat s t r a t i -graphy, and ultimately deposit size and shape. The i n d i v i d -ual peat deposits which have resulted w i l l ultimately form unique depositional settings for each of the corresponding coal seams. Boundary Bay peats w i l l produce thin, discontinuous bands of c o a l . These bands w i l l be interbedded with thin units of f o s s i l i f e r o u s sandy s i l t s t o n e and s i l t y mudstone. Coal lenses w i l l become more numerous and thicken over i n t e r -laminated f l u v i a l mudstone and s i l t y mudstone, u n t i l even-78' t u a l l y t h e y g r a d e i n t o t h i c k i n t e r d i s t r i b u t a r y seams o f t h e d e l t a p l a i n . U n d e r l y i n g t h e s e t h i n f l u v i a l u n i t s w i l l be a t h i c k s e q u e n c e of c o a r s e n i n g upward, p r o d e l t a - s i l t y mud-s t o n e s , s i l t s t o n e s , and f i n e - g r a i n e d s a n d s t o n e s . B o u n dary Bay c o a l s , u n l i k e t h o s e o f f r e s h w a t e r o r i g i n , w i l l c o n t a i n l a r g e amounts o f b o t h a s h and s u l p h u r . The a s h w i l l be composed p r i m a r i l y o f t h e c l a y m i n e r a l s i l l i t e a n d s m e c t i t e . S u l p h u r w i l l o c c u r d o m i n a n t l y as p y r i t e . B o t h L u l u I s l a n d and P i t t Meadows d e p o s i t s w i l l p r o d u c e r e l a t i v e l y t h i c k c o a l seams a s compared t o Boundary Bay. In c o n t r a s t t o t h e a l l u v i a l p l a i n seam a t P i t t Meadows, t h e d e l t a p l a i n c o a l s o f L u l u I s l a n d w i l l f o r m a l a t e r a l l y e x t e n -s i v e network o f seams. I n d i v i d u a l seams w i l l be s e p a r a t e d by f l u v i a l c h a n n e l f i l l u n i t s o f g r a d e d s a n d s t o n e and s i l t s t o n e . C o a l s p r o x i m a l t o c h a n n e l s w i l l c o n t a i n numerous p a r t i n g s o f s i l t y mudstone w h i c h u l t i m a t e l y w i l l r e d u c e seam t h i c k n e s s . Seams w i l l a l s o t h i n a p p r e c i a b l y o v e r a number of s m a l l e r s i l t y mudstone d i s t r i b u t a r y c h a n n e l s , c r e s t i n g a l o n g n a r r o w want a r e a s . C o a l s between t h e s e want a r e a s w i l l be u n d e r l a i n by mudstones o f p r e d o m i n a n t l y k a o l i n i t e and i l l i t e , a nd be-c a u s e of t h e i r b r a c k i s h w a t e r o r i g i n , w i l l have h i g h p y r i t e and a s h c o n t e n t s . The r e m a i n d e r o f t h e seam w i l l c o n t a i n b e t t e r q u a l i t y c o a l . F l u v i a l s e d i m e n t s a c c o m p a n y i n g t h e s e d e l t a p l a i n c o a l s w i l l be much t h i c k e r t h a n t h o s e p r e s e n t a t Boundary Bay. 79 They w i l l s t i l l r e m a i n t h i n , however, i n c o m p a r i s o n t o u n d e r -l y i n g p r o d e l t a s e d i m e n t s . The P i t t Meadows p e a t w i l l f o r m a s m a l l i s o l a t e d seam, s u r r o u n d e d by c h a n n e l f i l l s a n d s t o n e and a s s o c i a t e d l e v e e s of a r g i l l a c e o u s s i l t s t o n e . T h i n l y b e d d e d m u d s t o n e s u n d e r l y i n g t h e seam w i l l be composed c h i e f l y o f k a o l i n i t e , and w i l l g r a d e downward i n t o w e l l - s o r t e d s i l t s t o n e s and f i n e s a n d -s t o n e s . I n c o n t r a s t t o t h e seams o f B o u n d a r y Bay and L u l u I s l a n d , t h o s e o f P i t t Meadows w i l l c o n t a i n few p a r t i n g s , and w i l l m a i n t a i n a n e a r l y c o n s t a n t t h i c k n e s s . C o n c e n t r a t i o n s of s u l p h u r and a s h w i l l be low, and a s a r e s u l t , c o a l s p r o d u c e d w i l l be o f b e t t e r q u a l i t y . Due .to seam c h a r a c t e r i s t i c s , t h e P i t t Meadows c o a l s w i l l be t h e e a s i e s t t o mine. U n f o r t u n a t e -l y , i t may a l s o be t h e h a r d e s t seam t o l o c a t e u n l e s s i t i s i n i t i a l l y e x p o s e d a t s u r f a c e . The t h i c k s e q u e n c e of s a n d -s t o n e w h i c h w i l l s u r r o u n d t h e P i t t Meadows seam i s n o t b r o k e n by s e c t i o n s o f f i n e r m a r i n e s e d i m e n t , a s t h e y a r e on t h e d e l t a p l a i n . The f o r m a t i o n of c o a l s w i t h i n t h i s s e q u e n c e i s u n p r e d i c t a b l e , a s numerous e n v i r o n m e n t s s i m i l a r t o t h a t a t P i t t Meadows c o n t a i n no p e a t . 80 SUMMARY T h r e e p e a t - f o r m i n g e n v i r o n m e n t s were s t u d i e d f r o m d i f -f e r e n t d e p o s i t i o n a l s e t t i n g s on t h e R e c e n t l o b e o f t h e F r a s e r R i v e r d e l t a ( T a b l e 1 ) . P e a t s w h i c h have a c c u m u l a t e d on t h e i n a c t i v e p o r t i o n o f t h e d i s t a l l o w e r d e l t a p l a i n d e v e l o p e d from w i d e s p r e a d s a l t and b r a c k i s h m a r s h e s . T h e s e p e a t s were not i n f l u e n c e d a p p r e c i a b l y by f l u v i a l a c t i v i t y , a l l o w i n g t h e l a t e r a l d e v e l o p m e n t o f marsh f a c i e s t o be c o n t r o l l e d by a c o m b i n a t i o n o f c o m p a c t i o n and e u s t a t i c sea l e v e l r i s e . As a r e s u l t , an e x t e n s i v e t h i n b u t d i s c o n t i n u o u s p e a t n e t w o r k de-v e l o p e d , c o n t a i n i n g numerous i n t e r c a l a t e d s i l t y c l a y l a m i n a e and h i g h c o n c e n t r a t i o n s of s u l p h u r . These p e a t s o v e r l i e e i t h e r f i n i n g upward s i l t y s a n d , s i l t and s i l t y c l a y of f l u -v i a l o r i g i n o r homogeneous f i n e and s i l t y s a n d o f m a r i n e o r i g i n . U n d e r l y i n g b o t h of t h e s e t h i n u n i t s i s a m a j o r c o a r -s e n i n g upward s e q u e n c e o f p r o d e l t a s i l t y c l a y a n d s i l t . P e a t d e p o s i t s t r a n s i t i o n a l between t h e l o w e r and u p p e r d e l t a p l a i n have a c c u m u l a t e d i n f l u v i a l d o m i n a t e d e n v i r o n -ments. The r e l a t i v e l y t h i n f l u v i a l u n i t s a r e , however, un-d e r l a i n by a t h i c k s e q u e n c e o f p r o d e l t a s e d i m e n t s s i m i l a r t o t h o s e a c c o m p a n y i n g d i s t a l l o w e r d e l t a p l a i n p e a t s . E a r l i e s t p e a t s of t h e s e d e p o s i t s , h a v i n g d e v e l o p e d f r o m i n t e r d i s t r i b u -t a r y b r a c k i s h m a r s h e s , c o n t a i n l a r g e amounts o f s u l p h u r and numerous f i n e g r a i n e d s p l a y d e p o s i t s . I n d i v i d u a l p e a t h o r i -z ons a r e u n d e r l a i n by a f i n i n g upward s e q u e n c e o f f i n e s a n d , s i l t , and s i l t y c l a y , and a r e c o n f i n e d l a t e r a l l y by s i l t and 81 s i l t y c l a y o f s m a l l d i s t r i b u t a r y c h a n n e l s . T h i c k e s t p e a t s o c c u r i n a r e a s where t h e s e c h a n n e l s were abandoned e a r l i e s t . E x c e p t n e a r t h e m a r g i n s o f a c t i v e c h a n n e l s o r m a r i n e t r a n s -g r e s s i v e a r e a s , Sphagnum d o m i n a t e d b i o f a c i e s g r a d u a l l y r e -p l a c e s e d g e - g r a s s p e a t s u p s e c t i o n . T h e s e l a t e r p e a t s c o n t a i n l e s s s u l p h u r and fewer s p l a y s . P e a t d e p o s i t s w h i c h have d e v e l o p e d n e a r t h e b o u n d a r y between t h e a l l u v i a l and u p p e r d e l t a p l a i n r e p r e s e n t t h e c u l -m i n a t i o n o f a.major f i n i n g upward s e q u e n c e . U n l i k e l o w e r d e l t a p l a i n e n v i r o n m e n t s , an u n d e r l y i n g s e q u e n c e of p r o d e l t a s e d i m e n t s i s a b s e n t . I n i t i a l s e d g e - g r a s s p e a t s o v e r l i e i n t e r l a m i n a t e d • s i l t and c l a y o r f i n i n g upward c y c l e s o f s i l t y s and, s i l t , a nd c l a y o f f l o o d o r i g i n . T h e s e p e a t s have n o t been i n f l u e n c e d by b r a c k i s h w a t e r , and a s a r e s u l t , c o n t a i n low c o n c e n t r a t i o n s o f s u l p h u r . The p r e s e n c e of w e l l - d e v e l -oped n a t u r a l l e v e e s r e d u c e s t h e number and s i z e o f s p l a y s , r e s t r i c t i n g them t o s e d g e - g r a s s p e a t s m a r g i n a l t o a c t i v e c h a n n e l s . On o t h e r b o u n d a r i e s , p e a t s p r o g r a d e o v e r s i l t y c l a y w i t h s h a r p c o n t a c t s . T h i c k e s t p e a t s o c c u r i n b e l t s where s m a l l a v u l s e d f l o o d c h a n n e l s h a v e been f i l l e d w i t h s e d g e - c l a y , g y t t j a , a n d s e d g e - g r a s s p e a t . B i o f a c i e s p r e s e n t i n e a c h o f t h e t h r e e p e a t - f o r m i n g e n -v i r o n m e n t s a r e r e l a t e d t h r o u g h a common s u c c e s s i o n a l s e -q uence. The s e q u e n c e i s i n i t i a t e d when p i o n e e r i n g m a r i n e o r f r e s h w a t e r s e d g e - g r a s s c o m m u n i t i e s o c c u p y wet, d i s t u r b e d n i c h e s and m o d i f y them s u f f i c i e n t l y t o r e s t r i c t c l a s t i c s e d i -82 m e n t a t i o n . P r o v i d e d t h e s u b s t r a t e has been r a i s e d above b r a c k i s h w a t e r i n f l u e n c e by a c c u m u l a t i n g o r g a n i c m a t t e r , Sphagnum soon c o l o n i z e s t h e h a b i t a t . Once e s t a b l i s h e d , i t c r e a t e s a c i d i c , o l i g o t r o p h i c c o n d i t i o n s w h i c h a l l o w o n l y a c i d o p h i l e s t o s u r v i v e . E r i c a c e o u s s h r u b s , P t e r i d i u m and P i n u s c o n t o r t a , f o r m t h e b a l a n c e o f t h e c l i m a x s u c c e s s i o n a l s t a g e . In u p p e r d e l t a p l a i n - a l l u v i a l p l a i n e n v i r o n m e n t s where p e a t s o r i g i n a t e f r o m f r e s h w a t e r m a r s h e s , t h e s u b s t r a t e e q u i r e s l i t t l e m o d i f i c a t i o n b e f o r e Sphagnum i s a b l e t o c o l o -n i z e . As a r e s u l t , s e d g e - g r a s s p e a t s of a l l u v i a l p l a i n de-p o s i t s a r e much t h i n n e r t h a n s i m i l a r f a c i e s o r i g i n a t i n g on t h e d e l t a p l a i n . Nuphar p e a t s o c c u r o n l y i n Sphagnum and e r i c a c e o u s Sphagnum b i o f a c i e s o f d e l t a p l a i n p e a t s . T h e i r e x c l u s i o n f r o m a l l u v i a l p l a i n p e a t s r e s u l t s f r o m g r e a t e r p r e -c i p i t a t i o n i n t h i s r e g i o n . G y t t j a p e a t s a r e a b s e n t from l o w e r d e l t a p l a i n d e p o s i t s b e c a u s e t i d a l a c t i v i t y p r e v e n t s t h e a c c u m u l a t i o n o f o r g a n i c m a t t e r i n p o o l e d w a t e r n i c h e s . D i s t a l l o w e r d e l t a p l a i n p e a t s w i l l p r o d u c e l a t e r a l l y e x t e n s i v e b u t t h i n and l e n t i c u l a r c o a l seams. T h e s e c o a l s w i l l c o n t a i n , i n a d d i t i o n t o l a r g e c o n c e n t r a t i o n s of p y r i t i c s u l p h u r , h i g h a s h c o n t e n t s r e s u l t i n g f r o m numerous t h i n s p l i t s . C o n s e q u e n t l y , b o t h c o a l q u a l i t y and c a l o r i f i c v a l u e w i l l be low. Numerous t h i c k c o a l seams w i l l be d e v e l o p e d from t r a n s i -33 t i o n a l lower delta plain-upper delta pl a i n peats. Individual seams w i l l be separated by channel f i l l deposits, with coals being thinned appreciably by numerous s p l i t s marginal to these channels and by smaller channel f i l l units throughout the remainder of the seam. Coal q u a l i t y at the base of seams is poor, comparable to that present in d i s t a l lower delta pla i n c o als. The remaining upper portion of the seam, how-ever, w i l l contain only small amounts of both sulphur and ash. A l l u v i a l p l a i n peats w i l l produce i s o l a t e d thick coals surrounded by channel f i l l sands. Seam thickness w i l l remain nearly constant throughout, with very few s p l i t s . As a result of low ash and sulphur contents, a good q u a l i t y coal with high c a l o r i f i c value w i l l be produced. 84 REFERENCES Allen, E.A.D., 1978. Petrography and stratigraphy of Holocene coastal-marsh deposits along the western shore of Delaware Bay. University of Delaware Department of Geology Ph.D. thesis, 287 p. Anderson, J.A.R., 1964. The structure and development of the peat swamps of Sarawak and Brunei. Journal of Tro p i c a l Geography, v. 18, pp. 7-16. Bayliss, P., Levinson, A.A., and Klovan, J.E., 1970. Mineralogy of bottom sediments, Hudson Bay. B u l l e t i n Canadian Petroleum Geology, v. 18, pp. 469-473. Berner, R.A., 1971. P r i n c i p l e s of Chemical Sedimentology. McGraw H i l l Book Company, New York, 240 p. Blunden, R.H., 1973. Urban geology of Richmond, B r i t i s h Columbia. Adventures in Earth Sciences Series no. 15, Department of Geological Sciences, The University of B r i t i s h Columbia, Vancouver, 13 p. Casagrande, D.J., 1970. Geochemistry of amino acids in se-lected F l o r i d a peats. Unpublished Ph.D. thesis, The Pennsylvania State U n i v e r s i t y . Casagrande, D.J. and E r c h u l l , L.D., 1976. Metals in 85-Okefenokee peat-forming environments: r e l a t i o n to c o n s t i -tuents found in c o a l . Geochimica et Cosmochimica Acta, v. 40, pp. 387-393. Casagrande, D.J. and Ng, L., 1979. Incorporation of elemen-t a l sulphur in coal as organic sulphur. Nature, v. 282, pp. 598-599. Casagrande, D.J. and Park, K., 1978. Muramic acid l e v e l s in Okefenokee peat: the role of microorganisms in the peat-forming system. S o i l Science, v. 125, pp. 181-183. Casagrande, D.J., G r o n l i , K. , and Sutton, N., 1980. The d i s -t r i b u t i o n of sulfu r and organic matter in various frac-tions of peat: o r i g i n s of sulfu r in coal. Geochimica et Cosmochimica Acta, v. 44, pp. 25-22. Casagrande, D.J., Idowu, G. , Friedman, A., ejt a_l. , 1 979. H S incorporation in coal precursors: ori g i n s of organic s u l -phur in c o a l . Nature, v. 282, pp.. 599-600. Casagrande, D.J., S e i f e r t , K. , Berschinski, C , and Sutton, N., 1977. Sulfur in peat-forming systems of the Okefenokee Swamp and F l o r i d a Everglades: o r i g i n s of sulfur in c o a l . Geochimica et Cosmochimica Acta, v. 41, pp. 61-167. C e c i l , C.B., Stanton, R.W., and Dulong, F.T., 1980. 86 Geological controls on sul f u r content in coal. American Association of Petroleum Geologists B u l l e t i n , v. 64, pp. 689-690. Cohen, A.D., 1968. The petrology of some peats of southern F l o r i d a (with special reference to the o r i g i n of coal). The Pennsylvania State University Department of Geology, Ph.D. t h e s i s , 352 p. Envirocon, 1980. Fraser River Estuary habitat development program, C r i t e r i a Summary Report. Prepared for Department of Supply and Services, F i s h e r i e s and Oceans, Canadian W i l d l i f e Service and Public Works Canada by Envirocon Limited, Vancouver. 147 p. Fairbridge, R.W., 1976. E f f e c t s of Holocene c l i m a t i c change on some t r o p i c a l geomorphic processes. Quaternary Research, v. 6, pp. 529-556. Fisk, H.N., 1958. Recent M i s s i s s i p p i River sedimentation and peat acumulation. _in van Aelst, Ernest, editor: Congres pour 1'Advancement des Etudes du Stratigraphique et de Geologie du Carbonifere. 4th, Heerlen, Compte Rendu, v. 1, pp. 187-199. F r a z i e r , D.E. and Osanik, A., 1969. Recent peat deposits; Louisiana coastal p l a i n , i_n Dapples and Hopkins, editors: Environments of Coal Deposition. Geological Society of 87 America Special Paper Number 114, pp. 63-86. Given, P.H., 1972. B i o l o g i c a l aspects of the geochemistry of c o a l . Advances in Organic Geochemistry. International Series of Monographs in Earth Series, v. 33, pp. 69-92. Given, P.H. and M i l l e r , R.N., 1971. D i s t r i b u t i o n of forms of sulphur in peats rom saline environments in the F l o r i d a everglades. Abstracts of Geological Society of America Meeting, Miami, p. 580. Gleason, P.J., Piepgras., D., Stone, P.A., et a_l. , 1980. Radiometric evidence for involvement of foating islands in the formation of F l o r i d a Everglades tree islands. Geology, v. 8, pp. 195-199. Hansen, H.P., 1940. Paleoecology of two peat bogs in south-western B r i t i s h Columbia. American Journal of Botany, v. 27, pp. 144-149. Hebda, R.J., 1977. The paleoecology of a raised bog and as-sociated d e l t a i c sediments of the Fraser River Delta, B r i t i s h Columbia. The University of B r i t i s h Columbia, Department of Botany, PhD. thesis, 200 p. Horn, J . C , and Fern, J . C , 1979. Carboniferous depositional environments in the Appalachian region. 760 p. 83 Huddle, J.W. and Patterson, S.H., 1961. Origin of Pennsylvanian underclay and related seat rocks. Geological Society of America, B u l l e t i n 72, pp. 1643-1 660. Johnston, W.A., 1921. Sedimentation of the Fraser River Delta. Geological Survey of Canada, Memoir 125, 46 p. Johnston, W.A., 1922. The character of s t r a t i f i c a t i o n of the sediment in the Recent delta of Fraser River, B r i t i s h Columbia, Canada. Journal of Geology, v. 30, pp. 115-129. K e l l e r h a l s , P. and Murray, J.W., 1969. T i d a l f l a t s at Boundary Bay, Fraser River Delta, B r i t i s h Columbia. B u l l e t i n of Canadian Petroleum Geologists, v. 17, pp. 67-91 . Koch, J., 1966. Petrologische Untersuchungen an jungpleisto-zanen Schieferkohlen aus dem Alpenvorland, der Schweiz und Deutschlands mit Vergleichsuntersuchungen an Torfen. Diss. Techn. Hochsch. AAchen, 186 p. Koch, J., 1970. Petrologische Untersuchungen an niedersach-sischen Torfen und Weichbraun kohlen. Geol. Mitt., v. 10, pp. 113-150. Lavkulich, L.M., 1978. Methods manual, Pedology Laboratory. 89 Department of S o i l Science, The University of B r i t i s h Columbia, Vancouver, 224 p. Luternauer, J.L. and Murray, J.W., 1973. Sedimentation on the western delta-front of the Fraser River, B r i t i s h Columbia. Canadian Journal of Earth Sciences, v. 10, pp. 1642-1663. Lyngberg, E., 1979. The palynology and vegetative succession of a peat bog located at northern P i t t Meadows, B r i t i s h Columbia. The University of B r i t i s h Columbia, Department of Botany, B.Sc. thesis, 34 p. MacKintosh, E.E. and Gardner, E.H'.-, 1966. A mineralogical and chemical study of Lower Fraser River a l l u v i a l sedi-ments. Canadian Journal of S o i l Science, v. 46, pp. 37-46. Mathews, W.H. and Shepard, F.P., 1962. Sedimentation of Fraser River Delta, B r i t i s h Columbia. B u l l e t i n of the American Association of Petroleum Geologists, v. 46, pp. 1416-1438. Milliman, J.D., 1980. Sedimentation in the Fraser River and i t s estuary, southwestern B r i t i s h Columbia. Estuarine and Marine Science, v. 10, pp. 609-633. Osvald, H., 1928. Mossar ach mosskulture i Nordamerika. 90 Svenska Mosskulturfforeningenstidskrift, 42 och 43 Jonkoping. Osvald, H., 1933. Vegetation of the P a c i f i c Coast bogs of North America. Acta Phytogeographica Sueica, v. Almkvist and Wiksells, Botrycheri-A.B., Uppsala, 34 p. Osvald, H.', 1970. Vegetation and stratigraphy of peatlands in North America. Uppsala, Vetenskapssocieteten, Stockholm, Almkvist och Wiksell, 96 p. Pharo, CH., 1972. Sediments of the central and southern S t r a i t of Georgia, B r i t i s h Columbia. Department of Geology, The University of B r i t i s h Columbia, Ph.D. the-s i s , 2 90 p . Rampino, M.R. and Sanders, J.E., 1981. Episodic growth of Holocene t i d a l marshes in the northeastern United States: a possible indicator of eustatic sea l e v e l f l u c t u a t i o n s . Geology, v. 9, pp. 63-67. Rigg, G.B. and Richardson, CT., 1938. P r o f i l e s of some Sphagnum bogs of the P a c i f i c coast of North America. Ecology, v. 19, pp. 408-434. Shepperd, J.E., 1981. Development of a s a l t marsh of the Fraser Delta at Boundary Bay, B.C., Canada. The University of B r i t i s h Columbia, Department of Geological 91 Science, M.Sc. the s i s , 143 p. Spackman, W., Reigel, W.L., and Dolsen, CP., 1969. Geological and b i o l o g i c a l interactions in the swamp-marsh complex of southern F l o r i d a , j_n Environments of Coal Deposition, Geological Society of America Special Paper 114, pp. 1-36. Spackman, W., Cohen, A.D., Given, P.H., and Casagrande, D.J., 1974. The comparative study of the Okefenokee Swamp and the Everglades mangrove swamp-marsh complex of southern F l o r i d a . F i e l d Guide Book for Geological Society of America Meeting, Miami, p. 265. Staub, J.R. and Cohen, A.D., 1978. Kaolinite-enrichment beneath coals: A modern analog, Snuggedy Swamp, South Carolina. Journal of Sedimentary Petrology, v. 48, pp. 203-210. Staub, J.R. and Cohen, A.D., 1979. The Snuggedy Swamp of South Carolina: a back-barrier estuarine coal-forming environment. Journal of Sedimentary Petrology, v. 49, pp. 133-144. Styan, W.B. and Bustin, R.M., 1981. Sedimentology, petro-graphy and geochemistry of some peat deposits of the Fraser River Delta. Program with abstracts, Joint Annual Meeting, Geological Association of Canada; Mineralogical 92 Association of Canada, v . 6, p. 54. Swinbanks, D.D., 1979. Environmental factors c o n t r o l l i n g f l o r a l zonation and the d i s t r i b u t i o n of burrowing and tube-dwelling organisms on Fraser Delta t i d a l f l a t s , B r i t i s h Columbia. The University of B r i t i s h Columbia, Department of Geological Sciences and I n s t i t u t e of Oceanography, Ph.D. t h e s i s , 274 p. Williams, E.G. -and Keith, M.L., 1963. Relationship between sulfur in coals and the occurrence of marine roof beds. Economic Geology, v. 58, pp. 720-729. Zobell, C.E., 1963. Organic geochemistry of s u l f u r . i_n I.A. Breger, e d i t o r : Advances in Organic Chemistry. Pergamon Press, pp. 573-578. 93 PART I I : PETROGRAPHY OF SOME FRASER RIVER DELTA PEAT DEPOSITS ABSTRACT Integration of the decompositional history of ind i v i d u a l plant components with peat stratigraphy and depositional set-ting in three peat forming environments has allowed the pre-d i c t i o n of maceral precursors and subsequent microlithotype di s t r i b u t ion. Thin sedge-grass peats developed on inactive portions of the d i s t a l lower delta p l a i n . These peats were influenced by marine conditions near the base and freshwater conditions higher in the section. A high r a t i o of c e l l u l o s e to l i g h i n in marsh plants and l i m i t e d exposure of these tissues to des-iccation and oxidation produce primarily desmocollinite. Smaller amounts of cerenite, c u t i n i t e , and a l g i n i t e originate from a l g a l and sedge l i p i d s . In the t r a n s i t i o n to freshwater peats, ox y f u s i n i t e , p y r o f u s i n i t e and m i c r i n i t e p a r t i a l l y re-place former e x i n i t e and v i t r i n i t e group macerals. Later a l t e r a t i o n by transgressing marine waters further aids t h i s process. The l a t e r a l l y extensive but thin and discontinuous coal seams which would develop w i l l contain v i t r i t e bands near the base and w i l l grade upsection into inter laminated durite and v i t r i n e r t i t e . Peats deposited between upper originate from brackish water. As and lower delta p l a i n such, e a r l i e s t peat h o r i -94 z o n s c o n t a i n s i m i l a r m a c e r a l c o m p o s i t i o n s t o t h o s e e n c o u n -t e r e d i n d i s t a l d e l t a p l a i n d e p o s i t s . C r e v a s s e and f i r e s p l a y s d i s r u p t g r a d a t i o n a l c h a n g e s i n f a b r i c u p s e c t i o n and a l o n g c h a n n e l m a r g i n s . F l o o d i n g by o x y g e n a t e d , n e u t r a l pH w a t e r s , f o l l o w e d by e x t e n d e d p e r i o d s o f d e s i c c a t i o n , r e s u l t i n i n c r e a s e s of i n e r t o d e t r i n i t e , m a c r i n i t e , s c l e r o t i n i t e , and o x y f u s i n i t e . I n t e r l a m i n a t e d d u r i t e s and v i t r i n e r t i t e s w i l l f o r m common m i c r o l i t h o t y p e s . I n t e r b e d d e d bands of t e l e n i t e , c u t i n i t e a nd c e r e n i t e a r e p r o d u c e d by l a t e r f r e s h w a t e r s e d g e -g r a s s p e a t a c c u m u l a t i o n s . In t h i s b i o f a c i e s , c l a r i t e r e -p l a c e s d u r i t e . A f t e r c o l o n i z a t i o n by Sphagnum , l i g n i n r i c h t i s s u e s f r o m e r i c a c e o u s s h r u b s and P i n u s c o n t o r t a p r o v i d e p r e c u r s o r s f o r s u b e r i n i t e , t e l o c o l l i n i t e , and t e l e n i t e . Stumps of m a s s i v e t e l e n i t e i n t e r r u p t t h e s e banded m a c e r a l s . V i t r i t e w i t h t h i n l a m i n a e o f l i p t i t e a nd l e n s e s of c l a r i t e w i l l f o r m u p p e r p o r t i o n s o f t h e t h i c k and l a t e r a l l y e x t e n s i v e seams. U n l i k e d e l t a p l a i n p e a t s , a l l u v i a l p l a i n p e a t s o r i g i n a t e f r o m f r e s h w a t e r e n v i r o n m e n t s . E a r l i e s t m a c e r a l s f o r m e d r e -f l e c t t h i s d i f f e r e n c e . I n i t i a l c h a n n e l f i l l p e a t s , r i c h i n r e s i s t a n t b a r k and stem f r a g m e n t s , p r o d u c e v i t r i t i c c a r b a r g i -l i t e s c o n t a i n i n g s u b e r i n i t e , c o l l i n i t e , and v i t r o d e t r i n i t e . A l g a e and c u t i c l e s i n t h e o v e r l y i n g g y t t j a p e a t form l i p t i t e w i t h t h i n bands of c l a r i t e . B e c a u s e o f a common s u c c e s s i o n a l s e q u e n c e , t h e s e m i c r o l i t h o t y p e s g r a d e v e r t i c a l l y i n t o an a s -semblage o f m a c e r a l s s i m i l a r t o t h o s e f o u n d i n d e l t a p l a i n p e a t s . The d i s t r i b u t i o n o f t h e c l a r i t i c and v i t r i t i c ma-95 cerals w i l l , however, be less complex in the isol a t e d seams of the a l l u v i a l p l a i n . 96 INTRODUCTION The petrographic fabric and composition of peat is de-pendent on the types of plant communities, the climate, the ec o l o g i c a l conditions of the environment, and the degree of decomposition. Although species composition influences the i n i t i a l character and fab r i c of a peat, i t i s the effect of the physical environment on the early diagenesis of the com-munity that greatly modifies the f i n a l product (Stach, 1975). After b u r i a l , the e f f e c t s of temperature, and to a lesser extent pressure, govern a series of biochemical and chemical reactions which progressively transform peat into c o a l . During t h i s geochemical stage of organic metamorphism, the c h a r a c t e r i s t i c steps through which organic compounds are condensed and eliminated are predictable to a cert a i n extent ( F l a i g , 1968). The products of these reactions are, however, contingent upon the i n i t i a l reactants, which are determined from the a l t e r a t i o n of s p e c i f i c plant tissues during peat formation. Therefore biochemical processes strongly i n f l u -ence the ultimate formation of coal macerals. In the past coal petrography and associated spore and pollen assemblages were studied in an attempt to understand the ancient peat-forming environment (Moore, 1968; Teichmuller, 1958, 1968; Ting and Spackman, 1965; Hacquebard et a l . , 1967; Smith, 1962, and others). Decompositional pathways and tissue degradation were extrapolated from peat 97 (coal) b a l l s and stages of p a r t i a l l y c o a l i f i e d l i g n i t e s . Products rather than processes were studied, and l i t t l e at-tention was paid to modern analogs. More recently, the-petrographic study of modern peat has greatly added to the understanding of the transformation of peat to coal . These studies have largely been confined to subtropical and t r o p i c a l swamp environments in F l o r i d a (Cohen, 1968, 1970; Cohen and Spackman, 1977, 1980), South Carolina (Staub and Cohen, 1978, 1979), and Georgia (Cohen, 1973). The one exception i s the study by Alle n (1978) of some coastal marsh peats from Delaware. These investigations have enabled a better understanding and application of the processes leading to the formation of coal macerals in t r o p i -c a l and subtropical climates. They are limited, however, in the reconstruction of paleoecology and paleogeography of an-cient coal seams formed in temperate or subarctic environ-ments such as the Carboniferous to Permian coals of Gondwanaland. Extensive marshes developed on the Fraser River delta between 4350 and 4850 years B.P. (Hebda, 1977; Kellerhals and Murray, 1969; Shepperd, 1981; and t h i s study),. coincident with a decline in the rate of eustatic sea l e v e l r i s e (Mathews e_t a l . , 1970; Clague, 1975). Anastomosed r i v e r channels (Smith and Smith, 1980) r e s u l t i n g from this r i s e allowed accumulations of thick peats to occur in several d i s -t i n c t depositional settings. These peats thus provide an 93 ideal opportunity to describe the character, petrography, and decomposition of temperate peat deposits in a variety of en-vironments. The purpose of thi s paper i s to i d e n t i f y peat com-ponents, describe fabric r e l a t i o n s h i p s , and determine peat types in d i f f e r e n t environments; to compare and contrast l i v i n g tissues with peat in various stages of decomposition in order to es t a b l i s h decompositional pathways; and f i n a l l y to hypothesize as to the ultimate formation of coal macerals (precursors) for the d i f f e r e n t peat types. Regional Sett ing Peat deposition has a c t i v e l y occurred over extensive areas of the Fraser River delta in several d i s t i n c t deposit-ional settings, including the d i s t a l lower delta plain at Boundary Bay, the t r a n s i t i o n between upper and lower delta plains at Lulu Island and the upper delta p l a i n - a l l u v i a l plain at P i t t Meadows. The ages of these deposits range from 4,300 to 4,800 B.P. (Luternauer and Murray, 1973; Hebda, 1977; Teledyne #1-11.742, 1981) and correspond to a slowing in the rate of eustatic sea l e v e l r i s e (Fairbridge, 1976; Rampino and Sanders, 1981). Thin (less than half a meter), discontinuous sedge-grass peats have accumulated on the inactive portion of the delta between Point Roberts and Mud Bay. The Boundary Bay peat 99 consists of remnants of t h i s peat which are exposed along the shore of the t i d a l f l a t at the foot of 112th Street. These peats were flooded occasionally throughout th e i r development by storms, high tides, and spring freshets. As a r e s u l t , high concentrations of both ash and sulphur were introduced (Styan and Bustin, 1981). A marine transgression has halted growth, and i s presently a l t e r i n g and eroding these peats. L a t e r a l l y transported s i l t and s i l t y sand from the Point Roberts peninsula i s covering much of the deposit as well (Shepperd, 1981). Vast expanses of the Fraser River delta p l a i n are cov-ered with thick peat deposits. Abandoned d i s t r i b u t a r y chan-nels at the base of these deposits reduce peat thickness con-siderably in some areas. Brackish sedge-grass peats accumu-l a t i n g between the channels contain high concentrations of sulphur and, because of numerous crevasse splays, large amounts of ash as well. Larger f l u v i a l channels, which became dominant after the numerous d i s t r i b u t a r y channels were abandoned, confine the deposits l a t e r a l l y . S i l t y clay and sandy s i l t form levees, and occasionally splays are interca-lated with peat along these margins. Sedge-grass peats are most often present here, as they migrate v e r t i c a l l y in re-sponse to ac t i v e sedimentation. Otherwise peat fa c i e s are ho r i z o n t a l l y s t r a t i f i e d . The Lulu Island peat deposit i s c h a r a c t e r i s t i c of the delta p l a i n peats. The deposit i s sur-rounded on three sides by f l u v i a l channels, which were active throughout most of the peat accumulation. On the fourth 100 side, peat i s presently being eroded by the main channel of the Fraser River. Isolated thick peats have accumulated behind well devel-oped natural levees on the a l l u v i a l p l a i n . The margins of these deposits are often complex. The P i t t Meadows deposit formed in t h i s environment, where it merges with the upper delta p l a i n . On the inactive northern and eastern margins of the deposit, peats prograde over old natural levee and flood p l a i n units of s i l t and clay, while on the southern boundary, peats are intercalated with natural levee s i l t y clay depos-i t s . An erosional contact was produced through channel mean-dering on the western margin. Peat thickness i s almost con-stant. Thicker zones do occur, however, where sedge-clay and gytt j a peats f i l l small avulsed channels. Crevasse splays are not common, and the concentration of both ash and sulphur i s low. Peat facies maintain horizontal s t r a t i f i c a t i o n throughout much of the deposit (Styan and Bustin, 1981). The accumulation of these deposits in a variety of d i f -ferent environments i s u n i f i e d by a natural succession of similar peat types (Fig. 1 ) . Open sedge-grass marshes pro-duce low moor peats, which accumulate quickly in response to a high nutrient supply. These marshes modify the environment s u f f i c i e n t l y during th e i r development to r e s t r i c t sediment supply except during flood or storm events. Gramineae and Cyperaceae, the p r i n c i p a l peat-forming families, have exten-sive root systems, which quickly s t a b i l i z e any sediment 101 FIG1. PEAT SUCCESSIONAL SEQUENCE ericaceous Sphagnum fire Nuphar fire Sphagnum BOG PEATS sedge Sphagnum freshwater sedge grass MARSH PEATS brackish sedge grass sedge wood marine sedge grass marine sedge clay brackish sedge clay freshwater sedge clay 102 trapped by t h e i r numerous v e r t i c a l stems. V a r i a b i l i t y within these two plant groups allows several niches to be colonized. A s a l t marsh community of S a l i c o r n i a v i r g i n i c a , A t r i p l e x  patula, Di st i c h l i s spicata, Elymus m o l l i s , and T r i g l o c h i n  maritimum i s a c t i v e l y forming peat at Boundary Bay (Shepperd, 1981), while freshwater species l i k e Typha l a t i f o l i a , Calamogrost i s sp. " Scirpus spp., and Carex lyngbei are produ-cing s i m i l a r organic accumulations at P i t t Polder (Lyngberg, 1979). Hebda (1977) recognized a brackish water equivalent of these two niches on the delta front between the south and north arms of the Fraser River. The sedge-grass marshes are the i n i t i a l stage in a com-plex hydroseral succession. Accompanying s i l t and clay depo-s i t i o n , they eventually raise the substrate s u f f i c i e n t l y to minimize the.effects of any marine influence. In doing so they e s t a b l i s h quiet freshwater niches into which woody shrubs and Sphagnum spp. can invade. Colonization occurs soon afte r the cessation of inorganic sedimentation. How-ever, where s a l i n i t y i s i n i t i a l l y high, several metres of sedge-grass peat i s required to accumulate before Sphagnum can develop. Once established, Sphagnum r e s t r i c t s water flow and lowers both nutrient supply and pH (Moore and Bellamy, 1974). Ericaceous genera, which are able to tole r a t e low nutrient supply, q u i c k l y replace freshwater marsh species. Ledum  groenlandicum i s the dominant ericad of t h i s community, which 103 together with Vaccinium spp., Andromeda p o l i f o l i a , Kalmia  p o l i f o l i a , and Sphagnum spp., have l o c a l l y formed broad hum-mocks. W a t e r - f i l l e d depressions of various depths occur be-tween these raised areas. Deeper pools, averaging 0.5 m in depth, are floored with a dense bottom layer of Sphagnum  apiculatum, or liverworts, and are covered by a luxuriant stand of Nuphar lutea var. polysepala (Nymphaea, Oswald, 1933). Such depressions, referred to herein as Nuphar hol-lows, are gradually f i l l e d by d e t r i t a l plant material. In shallow depressions, Scirpus subterminalus, Rhynchospora alba and Oxycoccus quadripetalus appear together and independently with Sphagnum spp. Subsequently, these species are succeeded by ericaceous shrub communities. Small groups of Pinus  contorta grow inward from around the bog perimeter to com-plete the climax community (Hebda, 1977). In the ericaceous Sphagnum b i o f a c i e s , the f i n a l stage of the successional sequence, f i r e controls both species compo-s i t i o n and bog evolution. As a r e s u l t of changing substrate elevation, pH, and nutrient supply, components of the succes-sional sequence may be absent or repeated. Hebda (1977) u t i -l i z e d the influence of a f i r e to explain the c h a r a c t e r i s t i c hummocky topography in Burns Bog. The stratigraphic sequence predicted by his model: charcoal, followed by a thin layer of gyttja, sedge, Sphagnum peat, and f i n a l l y ericaceous Sphagnum peat was observed throughout the bog. Pure Sphagnum peat was also seen to o v e r l i e d i r e c t l y charcoal horizons. In these situations.prolonged burning must have formed depressions 104 well below the water table. The pools of water which even-t u a l l y formed were conducive only to Sphagnum growth. Stag-nant ditches observed in the bogs at the present time have a luxuriant growth of Sphagnum covering the bottom. Nuphar hollows are formed in a similar manner, but only during the hottest and most prolonged burns. The extent to which any f i r e burns i s dependent upon the l e v e l of the water table at that time. 105 METHODS L i t h o f a c i e s , b i o f a c i e s , and peat stratigraphy were de-termined in the three peat-forming environments by d r i l l i n g a t o t a l of 300 holes with a H i l l e r Corer. In order to charac-t e r i z e the petrographic v a r i a b i l i t y within the deposits, three representative cores from each of the Lulu Island and P i t t Meadows bogs and one from Boundary Bay were taken for detailed study. Due to the fibrous nature of the upper peat section, a hole was dug and peat blocks, 50 cm x 20 cm x 10 cm, were cut off. the wall to prevent compaction. The remain-der of the peat section was taken using a piston corer modi-fied from Cohen (1968). The piston was greased p r i o r to coring and shoved straight down without turning. Both blocks and cores were stored in a i r t i g h t containers to prevent mois-ture l o s s . From each core, blocks measuring 2 cm a side were cut and placed in soldered copper gauze holders of sim i l a r shape and size (Cohen, 1968; Cohen and Spackman, 1972). The blocks were oriented with respect to stratigraphic top, l a b e l l e d and then fixed in a solution of 10% formaldehyde, 10% acetic acid, and 80% ethanol before undergoing a serie s of dehydra-ting solutions (Fig. 2). After gradually increasing the ethanol concentration in a series of water/ethanol solutions, a pure ethanol endpoint was reached. The samples were then cleared by a sim i l a r set of ethanol/tertiary butyl alcohol solutions before being transferred to those containing t e r -106 t i a r y butyl alcohol and p a r a f f i n . Three to six hours were allowed between successive solutions in order to at t a i n com-plete impregnation (Gray, 1958). The f i n a l three steps were ca r r i e d out in an oven at 58° to 60°C. When the sample had been placed in 100% p a r a f f i n , i t was l e f t an additional 12 hours at elevated temperatures p r i o r to evacuation and cool-ing in a vacuum apparatus. The block was removed from the copper gauze upon cooling, and cut into quarters with a di a -mond saw, and then microtomed. Only one of the four blocks was mounted. A l l sections were v e r t i c a l l y oriented and cut to a thickness of 15yun. Due to natural coloration, no stain was necessary. For comparative purposes, approximately 17 plant genera common to bog and marsh environments were co l l e c t e d . The root, stem, and leaf of these plants were then impregnated with p a r a f f i n following the same procedure as described for peat. T h i r t y - f i v e sections were cut 15yum thick and stained with both safranin and fast green. Each section was examined under 100X and 250x magnifica-t i o n . Samples were not spaced regularly down the cores be-cause of the nature of the i n v e s t i g a t i o n . Rather, samples were chosen from representative peat types and the approxi-mate percentage of each constituent was estimated. FIG 2. SUMMARY : PETROGRAPHIC METHOD kill and fix dehydrate clear impregnate 10% formaldehyde 10% acetic acid 80%ethanol 1 90% water 80% 60% 40% 20% 10% 5% 0% 90% ethanol 80% 60% 40% 20% 10% 5%. 0% 10% ethanol 20% 40% 60% 80% 90% 95% 100% 10% tertiary butyl alcohol 20% 40% 60% 80% 90% 95% 100% 80% tertiary butyl 60% 40% 0% alcohol 20% paraffin 40% 60% j 100% 12 hours at 60~C then cool under vacuum I cut into four I mount and microtome to 15 pm prepare slide 108 RESULTS Eight d i s t i n c t peat types are recognized and described from the three peat-forming environments. The d e s c r i p t i v e nomenclature used i s similar to that of Cohen (1968) and Cohen and Spackman (1977). Enough v a r i a t i o n in tissue degra-dation i s present in these peat types to allow the p a r t i a l decompositional pathways of 10 genera to be outlined. The synthesis of t h i s information with the results from sedimen-tology and peat stratigraphy (Styan and Bustin, 1981) allow the p o t e n t i a l maceral composition of the three environments to be determined. Peat Description Sedge-Clay Peat a. Petrographic C h a r a c t e r i s t i c s Sedge-clay peat consists of a mixture of both organic and mineral components. K a o l i n i t e - r i c h mud i s modified by the interbedding of wood, bark fragments, and sedge.stems in horizontal o r i e n t a t i o n and by the v e r t i c a l penetration of sedge, grass, and Equisetum stems. Small black and yellow rootlets are pervasive. Depending on the concentration of organic material, t h i s peat grades from a granular tan grey to a fragmental l i g h t chocolate brown unit. 109 In microtome section, highly oxidized and degraded grass and sedge remains are interlaminated with thin clay horizons in levee deposits or cut i r r e g u l a r l y through massive clay material in a l l u v i a l p l a i n deposits. Sedge and grass root-l e t s are also v i s i b l y degraded within the clay unit, but to a much lesser degree than material which has been exposed. The r a t i o of framework to matrix i s low. Except for periderm fragments and red-orange c e l l inclusions, few c e l l fragments are v i s i b l e in the abundant matrix. Diatoms are common in t h i s peat type, but the species composition varies with environment. Concentric diatom genera seemed to be confined to marine and-brackish waters. Ostracods.and foraminifers are common. Their d i s t r i b u t i o n i s similar to sedge grass peats. A few fungal spores are present, but hyphae are absent. Charcoal horizons are common in levee deposits; however, only d e t r i t a l fragments occur elsewhere. Pollen assemblages are e n t i r e l y dependent on the sur-rounding environment, but S a l i x , Betula, and Alnus are often abundant. Clay and fine d e t r i t a l quartz are common. b. Environment of Deposition Sedge-clay peats represent the i n i t i a l establishment of 1 101 a permanent organic component in the t r a n s i t i o n from a f l u -v i a l l y influenced environment. Sedge and grass species build up the substrate by trapping and binding any intrusion of c l a s t i c sediment. The addition of allochthonous wood and bark material during floods may also be s i g n i f i c a n t to the' accumulation of organic material. Between flood events, des-i c c a t i o n and oxidation may further decompose matter which has already been exposed to highly oxygenated flowing water. Species composition varies with the environment of depo-s i t i o n . In freshwater communities, Typha, Spirea, Betula, Alnus, and Salix are present in addition to sedges and grasses, while S a l i c o r n i a , A t r i p l e x , and T r i g l o c h i n are the pioneering genera in the t r a n s i t i o n from s a l t water (Shepperd, 1981). Gyttja Peat a. Petrographic C h a r a c t e r i s t i c s No macroscopic fragments are v i s i b l e in hand sample, due to intense degradation. The r e s u l t i n g products of decomposi-tion y i e l d a yellow brown to black, fine granular organic muck. Upon oxidation, this mixture of peat and water turns black. In microtome section, r o o t l e t s of sedges and grasses are the only i d e n t i f i a b l e plant organs. They are ' f l o a t i n g ' in 111 abundant yellow-brown amorphous material which comprises about 90 to 95% of the sample. Also scattered randomly throughout the matrix are small periderm c l u s t e r s and pieces of c u t i c l e . Few c e l l inclusions are. observed. Diatoms are abundant, e s p e c i a l l y near the t r a n s i t i o n with inorganic sedi-ments. Foraminifera and ostracods are rare, probably i n d i c a -ting a low pH during deposition or diagenesis. D e t r i t a l charcoal fragments are uncommon. Fungal hy-phae, when observed, are associated with degraded grass cu-t i c l e s . Fungal spores are more common, but not abundant. Pollen consists mainly of Pinus, Alnus, and S a l i x , with some Cyperaceae and Gramineae. Fine d e t r i t a l quartz and clay form a high percentage of the matrix near the t r a n s i t i o n with sedge-clay peats. b. Environment of Deposition Gyttja i s the f i n a l product of intense degradation of plant tissue in ponded water. Because t h i s g y t t j a was formed from a freshwater marsh assemblage, the contributing plant genera are Carex, Juncus, Typha, Calamogrostis, and Spirea. During flood events, allochthonous gymnosperm bark and wood fibres may also have been added to the biomass. Material must have decomposed via b a c t e r i a l metabolic pathways, con-sidering the paucity of fungal hyphae. 1 1 2 Sedge-Grass Peat In hand samples, sedge-grass peats are fibrous to fine granular. On freshly exposed surfaces t h e i r color varies from a l i g h t yellow-brown to a dark chocolate brown, but a l l surfaces exhibit a dark brown to black color upon oxidation. Large orange Carex seeds, small black bean-shaped seeds, Carex culms and blades, Ledum, Betula, and grass stem frag-ments are the only recognizable plant remains in an otherwise highly degraded mass of t i s s u e . Although much of this ma-t e r i a l i s horizontal and hypautochthonous in o r i g i n , a smal-l e r , less degraded component has v e r t i c a l o r i e n t a t i o n . Small pieces of charcoal occur throughout, and are p a r t i c u l a r l y abundant near the top of the peat. Microscopically, grass, sedge, l e a f , stem, and root tissue are randomly oriented in a matrix of amorphous yellow material (Plates 1-3). Minor framework components, Ledum stems and roots, and Betula stems show no preferred orienta-tion either, and as a r e s u l t , microbedding i s poorly devel-oped. Roots dominate over sedimentary framework fragments. The roots are less decomposed, and hence show a smaller amount of compaction than the remainder of the framework. The r a t i o of framework to matrix i s variable, depending on the environment in which the peat was deposited. In the marine-influenced peats at Boundary Bay, due to a high degree of degradation, the r a t i o i s very low (Plate 1, Figs. 3,4,5). 113 It increases in the brackish and freshwater sedge-grass peats of Lulu Island and P i t t Meadows. Most c e l l inclusions are secondary in o r i g i n , with the exception of primary red brown inclusions in ericaceous ma-t e r i a l . The inclusions appear to be globules of resins, gums, and tannins. They occur as yellow brown c e l l i n f i l -l i n g s in root endodermis and p e r i c y c l e and as individual orange to brown globules in the matrix. Globules in marine influenced peats have darker orange red c o l o r s . Marine sedge-grass peats are distinguished from those of freshwater o r i g i n by the occurrence of concentric diatoms, r e t i c u l a t e to spiny ostracods, and agglutinated foraminifers. In brackish water peats, concentric diatoms and agglutinated foraminifers are present, but r e t i c u l a t e ostracods are re-placed by smooth-shelled v a r i e t i e s . Fungal hyphae and spores are common in freshwater sedge-grass peats, but decrease in density in those peats of brack-ish to marine o r i g i n . In a l l environments, hyphae are less evident than sporangia and spores. Charcoal fragments occur in a l l environments, but are small and rounded. Most fragments are confined to the upper, more emergent sections of t h i s peat. Those pieces of char-coal found at lower levels of the peat are considered to have an allochthonous o r i g i n . - 1 1 4 Pollen assemblages vary considerably between each of the three environments. Cyperaceae pollen i s the dominant nonar-boreal pol l e n , followed by Gramineae pollen and monolete fern spores. In marine dominated peats, Spirea pollen are absent and are replaced by Chenopodiceae pollen, such as A t r i p l e x and S a l i c o r n i a (Shepperd, 1981). Other halophyte pollen are also present. Brackish water sedge-grass peats are similar to freshwater peats on the basis of pollen alone, although both gramineae and Typha pollen are more abundant in fresh-water assemblages. Thin units of s i l t y clay and s i l t , representing crevasse splays, are interbedded with t h i s peat type lower in the stratigraphic sections of both the Lulu Island and P i t t Meadows deposits. The peat at Boundary Bay contains s i g n i f i -cant s i l t and clay, but they are f i n e l y dispersed throughout the section and d i f f i c u l t to see microscopically. b. Environment of Deposition Sedge-grass peats accumulate unaffected by f l u v i a l sedi-ment except near channel margins, where the intrusion of cre-vasse splay deposits are common. These sharply bounded units grade from thick deposits of fine sand near the channel margin to thin s i l t y clay deposits in d i s t a l i n t e r d i s t r i b u -tary peats. Splays are modified by the growth of sedge and grass, stem and leaf tissue v e r t i c a l l y through the sediment. 1 1 5 As an emergent b i o f a c i e s , sedge-grass marshes develop in numerous environments. Boundary Bay sedge-grass peats repre-sent an accumulation of marsh debris near salt water. As a r e s u l t , plant debris i s highly degraded and altered, with high sulphur concentrations (Styan and Bustin, 1981). Recent sa l t marshes comprise only a small percentage of the delta surface, and are i s o l a t e d in narrow bands on Roberts Bank and at Boundary Bay (Plate 1, F i g . 1). The t y p i c a l species, Di st i c h y l i s spicata, S a l i c o r n ia v i r g i n i c a , A triplex patula, Gr i n d e l i a integr i f o l i a , and T r i g l o c h i n maritima are zoned with respect to s a l t tolerance and substrate elevation (Shepperd, 1981). Elymus m o l l i s and Juncus baiticus are other common peat-forming species. Abundant woody material and numerous large logs have been washed up and incorporated into these s a l t marsh environments. Brackish water sedge-grass peats are developing at the present time on the western sides of Lulu and Sea Islands between the north and south arms of the Fraser River (Plate 2, Fig.2). This niche contains species which vary consider-ably in their tolerance to s a l i n i t y . Sc i rpus amer icanus growth i s confined to the s a l t i e r lower reaches (Plate 2, F i g . 2), while Carex lyngbei forms almost exclusive stands higher in the marsh (Envirocon, 1981). Other species include Eleocharis sp., Scirpus maritimus, and Typha l a t i f o l i a (Hebda, 1977). Freshwater marshes produce the least decomposed peats. 116 Presently they are forming in narrow enclaves along the P i t t River and on the broad f l a t s of P i t t Polder (Plate 3, F i g . 1). Typical species composition includes Equisetum  spp., Scirpus validus, Scirpus microcarpus, Typha l a t i f o l i a , Carex costrata, and Calamogrost i s sp. (Envirocon, 1981). Sphagnum spp. often occurs as dense growths between these sedge grass communities (Lyngberg, 1979). Sedge Wood Peat a. Petrographic C h a r a c t e r i s t i c s This peat has similar color and texture to sedge-grass peats. However, i t contains thin horizons composed exclus-ively of Betula stem and branch fragments and abundant tree stumps (Plate 3, F i g . 1). The larger stumps are a mixture of Picea s i t c h e n s i s and Populus trichocarpa, while the smaller ones can be i d e n t i f i e d as Pinus contorta. A l l of the stumps appear to be in growth position, and hence autochthonous, whereas some stem and branch fragments have been transported. The peat i s dominated by a mixture of Ledum stems and roots, Betula stems, and Carex stems, roots, and rootl e t s (Plate 5, F i g s . 3-5). Juncus r o o t l e t s , grass stems, Sphagnum leaves and stems, and Oxycoccus stems can also be i d e n t i f i e d microscopically (Plate 5, F i g . 2), but comprise a smaller percentage of the framework. Highly degraded leaf tissues are common, but cannot be d i f f e r e n t i a t e d . 1 1 7 Leaf and stem tissues are s l i g h t l y oriented, but only thinner components l i k e sedge and Sphagnum produce d i s t i n c t microbedding. Betula stems in pa r t i c u l a r are compressed elongate along the plane. Roots and rootlets show l i t t l e compaction and no or i e n t a t i o n . The r a t i o of framework to matrix is high, and only small pockets of yellow to yellow orange amorphous gel are v i s i b l e . Within these pockets, minor leaf parenchyma, periderm, cu-t i c l e , and vascular bundle sheath c e l l fragments occur. The small amount of amorphous matrix i s inconsistent with the degree of decomposition of some tissues. Some degraded ma-t e r i a l must therefore have been leached by water. Red primary c e l l inclusions occur in the p i t h region of Ledum and Oxycoccus stems, whereas brown primary c e l l i n c l u -sions occur in the p i t h of Betula and the secondary phloem of Ledum and Oxycoccus roots and stems. I r r e g u l a r l y shaped red brown secondary c e l l inclusions occur in the palisade of de-composed leaf fragments, the xylem of Betula, and the peat matrix. Yellow brown c e l l inclusions also f i l l the endoder-mis and cortex of sedge r o o t l e t s . A few diatoms and smooth-shelled ostracods, but no fora-minifera, were observed in t h i s peat. However, both fungal hyphae and spores occur. They are most abundant throughout the matrix and near decomposing leaf tissue. Small, rounded charcoal fragments are common higher in the section, but at 1 1 8 depth are rare. Mineral matter was not observed. b. Environment of Deposition Sedge-wood peats develop on the flanks of natural l e -vees. Such an environment, through annual flood events, sup-p l i e s the abundant nutrients necessary to support a large biomass. At the same time, the levee also r e s t r i c t s any large intrusion of mineral matter into the peat. Populus  trichocarpa and Picea s i t c h e n s i s occupy the more stable posi-tions on the levee flank and top. These genera grade l a t e r -a l l y into Betula spp. and f i n a l l y Pinus contorta near the boundary of the Sphagnum b i o f a c i e s . Close to active chan-. nels, Populus and Picea give way to a narrow fringe of Alnus and S a l i x . The understory consists of Pter idium, Lysichiton, Typha l a t i f o l i a , and Carex spp. The small amount of charcoal in t h i s environment sug-gests that either the peat seldom dries s u f f i c i e n t l y to burn or that water flow has s e l e c t i v e l y winnowed out the charcoal. As Betula stem fragments and degraded material have also been transported, the l a t t e r a l t e r n a t i v e seems more p l a u s i b l e . Sedge-Sphagnum Peat a. Petrographic C h a r a c t e r i s t i c s Sedge-Sphagnum peat represents a gradational but d i s -1 1 9 t i n c t f a c i e s in the t r a n s i t i o n from sedge-grass to Sphagnum-dominated peats. It. i s red-brown and has a fibrous texture. The framework is composed p r i m a r i l y of Sphagnum ssp. Due to the low degree of decomposition, h o r i z o n t a l l y aligned stems of Ledum groenlandicum, Kalmia microphylla, and Oxycoccus  quadripetalus and v e r t i c a l l y oriented culms of Rhynchospora and Carex are v i s i b l e . Microscopically, Ledum, Kalmia, and Oxycoccus leaves and sedge, grass, and Ledum roots also can be i d e n t i f i e d (Plate 4, Figs. 2-5). Sphagnum and sedge tissues comprise between 50% and 80% of the framework material. Sphagnum leaves and degraded sedge leaf tissue and the orientation of ericaceous leaves form a well defined microbedding. Very l i t t l e compac-tion i s observed in stem and root tissue and, as a r e s u l t , they do not aid in the cha r a c t e r i z a t i o n of bedding. The r a t i o of framework to matrix i s lower than for pure Sphagnum peat, but higher than that of ericaceous Sphagnum peat. Matrix comprises 10% to 25% of the t o t a l peat, and i s extremely var i a b l e . The matrix forms thin, elongate lenses, which are composed of equal proportions of yellow-brown gel and c e l l fragments. Periderm, palisade layers, and i n d i v i d -ual parenchyma c e l l s are a l l recognizable components. Ericaceous stem p i t h and secondary phloem tissues con-tain red-brown to brown primary c e l l inclusions. Endodermis of sedge and grass rootl e t s i s f i l l e d with yellow-brown se-1 20 condary c e l l i nclusions. Similar orange to red-brown i n c l u -sions f i l l some spongy mesophyll, palisade, and epidermal tissues in p a r t i a l l y degraded ericaceous leaves. Diatoms and foraminifera are not present, whereas smooth-shelled ostracods are common. Fungal hyphae and spores are associated primarily with the sedge-grass and matrix components of t h i s peat. Even though fungal s c l e r o t i a are common constituents, they form only about 1 to 2% of the t o t a l peat volume. Charcoal i s rare and, where present, i s in tiny rounded fragments. Sphagnum spores are the most abundant palynomorphs. They occur i n d i v i d u a l l y and in clu s t e r s of t h i r t y or more (Plate 7, F i g . 2). Monolete fern, Ericaceae, Pinus, Cyperaceae, and Gramineae palynomorphs are a l l present, but minor contributors to the pollen assemblage. There i s no mineral matter in t h i s peat. b. Environment of Deposition Sedge-Sphagnum peats represent a t r a n s i t i o n a l environ-ment. Ericaceous shrubs and Sphagnum gradually replace wet sedge-grass peats, and in doing so cause the environment to become is o l a t e d from nutrient sources, the pH to decline, and the preservation of plant tissues to increase. As bacteria become r e s t r i c t e d by lowering of the pH, fungi assume the 121 role of dominant decomposer. Rainwater replaces runoff and groundwater as the nutrient source. Nuphar Peat a. Petrographic C h a r a c t e r i s t i c s Megascopically, Nuphar peat i s golden orange in color. The peat framework i s composed of a heterogeneous mixture of leaf and stem fragments, which produce a granular texture. A series of horizontal bedding planes are marked by the l a t e r a l growth of large liverwort t h a l l i (Plate 6, F i g . 4). Pinus needles, Sphagnum stems, and Carex culms and seeds can be i d e n t i f i e d throughout the matrix of the peat. Charcoal is absent. Ledum groenlandicum, Kalmia p o l i f o l i a , and Oxycoccus  quadripetalus stem and leaf fragments and Pinus contorta needles are recognizable in microtome section. The orienta-tion of some leaves.is the only suggestion of microbedding. The remainder of the framework components occur disseminated throughout a yellow-orange amorphous matrix comprising be-tween 40% and 60% of the peat. Roots are absent, except near the upper t r a n s i t i o n with Sphagnum peat. There, Ledum, Oxycoccus, and Rhynchospora roots are abundant. The matrix contains a large number of c e l l fragments (Plate 6, F i g . 4). Epidermal, peridermal, and palisdade 122 c e l l s from ericaceous leaves and stems as well as Nuphar t r i -chomes and a s t r o s c l e r e i d s are the degraded remnants of i n -tense biodegradation (Plate 6, F i g . 5). In larger leaf frag-ments of both Ledum and Kalmia, spongy mesophyll and lower epidermis are decomposed. The stem and root tissues of these plants show less degradation, but secondary xylem and c o r t i -c a l c e l l s are thinned, broken, and p a r t i a l l y replaced. Primary c e l l inclusions are evident in ericaceous p i t h , phloem, and metaxylem elements. Pinus needles also contain similar red c e l l inclusions in the transfusion t i s s u e . F o l -lowing p a r t i a l degradation, brown to yellow-brown secondary c e l l inclusions are evident in ericaceous leaf palisade and upper epidermis, in ericaceous stem phloem, and in Pinus needle mesophyll. Small whorled foraminifers, diatoms (Navicula spp.) and d i n o f l a g e l l a t e cysts are evident. Fungal hyphae are pervasive throughout the matrix, but never a t t a i n high concentrations. Large p a r t i a l l y - f i l l e d sporangia and spores are more common. Neither charcoal nor mineral matter i s present. Nuphar and Cyperaceae pollen dominate. Gramineae, Ericaceae, monolete fern, and Pinus are also observed. 123 b. Environment of Deposition Nuphar peats are deposited in shallow, w a t e r - f i l l e d de-pressions of small areal extent. The pools are covered with a dense growth of Nuphar lutea var. polysepala( Nymphaea Osvald, 1933) (Plate 6, F i g . 1), and sharply bounded by Ledum -Sphagnum communities. The pool bottom i s layered with l i v -erworts or Sphagnum apiculatum, and gradually accumulates d e t r i t a l plant material. Liverworts eventually are replaced with sedge-grass and f i n a l l y Sphagnum capillaceum-papillosum commun i t i e s . The o r i g i n of th i s peat type, from w a t e r - f i l l e d depres-sions, explains the lack of charcoal, the intense decomposi-ti o n , and the peculiar assemblage of plant remains. Sphagnum Peat a. Petrographic C h a r a c t e r i s t i c s Megascopically, Sphagnum peat varies from golden yellow to orange brown, and i s coarsely fibrous. The peat is only s l i g h t l y degraded, and Pinus contorta stumps, roots and stems, Rhynchospora alba stems, and Oxycoccus quadripetalus runners and leaves can be i d e n t i f i e d . D i s t i n c t horizontal partings define individual layers of compressed Sphagnum. Oxycoccus runners l i e along these planes in no preferred or i e n t a t i o n , while Rhynchospora stems cut obliquely through 124 them. In microtome sect i o n , - r o o t l e t s of Rhynchospora can be i d e n t i f i e d in addition to those plant fragments recognizable in hand sample. Sphagnum stem and leaf tissues comprise be-tween 80 to 90% of the framework in most peat. Their golden brown tissues appear l i g h t e r than the small l e n t i c u l a r pock-ets of yellow-orange amorphous gel which occurs between them (Plate 7, F i g . 5). The shape of these pockets along with the small amount of compression of Sphagnum tissues produce a well developed microbedding (Plate 7, F i g . 4) The r a t i o of framework to matrix i s high. With the ex-ception of Pinus rhytidome, few c e l l fragments are v i s i b l e . Primary c e l l inclusions are found in the pith and secondary phloem of Pinus and Oxycoccus stems where they occur as small red to brown globules. Yellow-brown secondary c e l l i n c l u -sions f i l l the endodermis of Rhynchospora roots and the p a l i -sade mesophyll of p a r t i a l l y degraded Oxycoccus leaves. Several smooth-walled ostracods were observed, but no foraminifera or diatoms were seen. The r e l a t i v e l y few fungal hyphae which are present in t h i s peat type are concentrated in gyttja pockets and between Sphagnum leaves. Charcoal fragments, although present, are rare. Small pods of e r i c a -ceous pollen occur. These pollen masses probably res u l t from flowers f a l l i n g onto the peat and l a t e r decomposing (Plate 7, F i g . 2). Individual Pi nus, Sphagnum, monolete fern, 12 5 G r a m i n e a e , and C y p e r a c e a e p o l l e n a r e a l s o d i s t r i b u t e d t h r o u g h o u t t h e p e a t . No m i n e r a l g r a i n s were o b s e r v e d . b. E n v i r o n m e n t o f D e p o s i t i o n P u r e Sphagnum p e a t s a p p e a r c o n s i s t e n t l y a b o v e ma j o r c h a r c o a l h o r i z o n s , and t h e r e f o r e a r e c o n s i d e r e d t o r e p r e s e n t a p i o n e e r i n g s t a g e f o l l o w i n g f i r e s . In o r d e r t o i n i t i a t e t h i s s e q u e n c e , f i r e s must be c a p a b l e not o n l y of d e s t r o y i n g e r i c a c e o u s s h r u b s l i k e Ledum a n d K a l m i a , b u t o f c r e a t i n g d e -p r e s s i o n s d e e p enough t o h o l d p o n d e d water a s w e l l . When t h i s o c c u r s , Sphagnum s p p . a r e a b l e t o o u t c o m p e t e e r i c a c e o u s . s h r u b s f o r r e c y c l e d n u t r i e n t s . Once e s t a b l i s h e d , Sphagnum spp . m o d i f y t h e n i c h e s u f f i c i e n t l y t o e x c l u d e a l l b u t O x y c o c c u s q u a d r i p e t a l u s and l a t e r R h y n c h o s p o r a a l b a ( P l a t e 7; F i g . 1 ) . A f t e r a t i m e , t h e Sphagnum p r o d u c e s hummocks t h a t r i s e w e l l a b o v e s l o w e r - a c c u m u l a t i n g s u r r o u n d i n g e r i c a c e o u s Sphagnum p e a t s . Sphagnum p e a t s become d r y enough t o a l l o w e r i c a c e o u s c o l o n i s a t i o n (Hebda, 1977). The s m a l l e r t h e i n i -t i a l p o n d e d a r e a , t h e s h o r t e r t h e t r a n s i t i o n f r o m Sphagnum t o e r i c a c e o u s Sphagnum p e a t . Where t h e h i g h l y a c i d i c n a t u r e o f t h e Sphagnum s u b s t r a t e i s c o m b i n e d w i t h a w a t e r - d o m i n a t e d n i c h e , b o t h b a c t e r i a l and f u n g a l d e g r a d a t i o n a r e low. O n l y m a t e r i a l w h i c h r e m a i n s above t h e p e a t s u r f a c e f o r l e n g t h y p e r i o d s o f t i m e i s decom-p o s e d . 126 E r i c a c e o u s Sphagnum P e a t a. P e t r o g r a p h i c C h a r a c t e r i s t i c s E r i c a c e o u s Sphagnum p e a t i s y e l l o w - b r o w n t o r e d - b r o w n , d e p e n d i n g on t h e c o n c e n t r a t i o n o f woody stem and r o o t t i s s u e . On e x p o s u r e t o a i r , i t o x i d i z e s t o a d a r k c h o c o l a t e brown. The p e a t i s w e l l b e d d e d , and has a f r a g m e n t a l t o f i b r o u s t e x -t u r e , due t o t h e abundance of Ledum g r o e n l a n d i c u m , K a l m i a  m i c r o p h y l l a , a n d V a c c i n i u m spp . m a t r i x . S m a l l p i e c e s o f c h a r c o a l a r e a b u n d a n t . The c o m p o s i t i o n of e r i c a c e o u s Sphagnum p e a t i s v a r i a b l e , and r a n g e s f r o m a l m o s t p u r e Sphagnum t o d o m i n a n t l y e r i c a c e o u s d e b r i s ( P l a t e 8, F i g . 4). Most o f t e n , i n m i c r o t o m e s e c t i o n , e r i c a c e o u s l e a f , stem, and r o o t f r a g m e n t s a r e i n t e r b e d d e d w i t h m o d e r a t e l y c o m p r e s s e d Sphagnum l e a v e s and t h i n bands of red-brown amorphous m a t e r i a l ( P l a t e 8, F i g . 5). In p e a t s composed of abundant e r i c a c e o u s d e b r i s , c h a r -c o a l h o r i z o n s a r e more common and d e c o m p o s i t i o n more a d -v a n c e d . O f t e n b e n e a t h a c h a r c o a l band a l l t h a t r e m a i n s i s a band o f o r a n g e - r e d g r a n u l a r g e l , t h r o u g h w h i c h a r e d i s p e r s e d a b undant f u n g a l hyphae ( P l a t e 8, F i g . 3). In t h e s e r e g i o n s , m i c r o b e d d i n g i s a c c e n t u a t e d by t h e c o l l a p s e o f d e g r a d e d stem t i s s u e , b u t d i s r u p t e d by t h e i n t e n s e r o o t i n g o f R h y n c h o s p o r a , E r i o p h o r u m , and Ledum. 12 7 Sphagnum leaves are more abundant in unburned zones, confining fungal hyphae to thin regions around ericaceous fragments where pH conditions are more a l k a l i n e . As a re-s u l t , most tissues are less degraded, and leaves, as well as stems, are recognizable (Plate 8, F i g . 2). Throughout these layers Oxycoccus, Vaccinium, Ledum, and Pinus roots are scat-tered. The r a t i o of framework to matrix i s high in unburned Sphagnum-rich zones, but considerably lower in ericaceous-r i c h zones. Amorphous lenses contain abundant secondary phloem and rhytidome c e l l fragments. Primary c e l l inclusions occur in p i t h , secondary phloem, and protoxylem of most ericaceous stems and root t i s s u e . These inclusions are red to red-brown, and have spherical shapes. Those of secondary o r i g i n include brown and red-brown c e l l f i l l i n g s in ericaceous leaf epiderm and palisade, stem pi t h , and secondary phloem and root secondary phloem. Some Sphagnum stems also show deposition of secondary c e l l material. Diatoms are absent, whereas c h i t i n i f e r o u s foraminifers and smooth-shelled ostracods are present in minor amounts. b. Environment of Deposition Ericaceous Sphagnum peat develops best in the dry niches 128 of the climax successional stage. As a r e s u l t , t h i s peat i s affected more extensively by f i r e than the surrounding pure Sphagnum or Nuphar peats which form in the intervening de-pressions. Unless a f i r e i s severe, bog l i t t e r i s simply recycled to be used by the f i r e - r e s i s t a n t ericaceous genera. Numerous f i r e s , however, increase pH, allow for greater bac-t e r i a l decomposition, and as a res u l t slow peat accumulation. In time the surrounding peat types r i s e above these e r i c a -ceous lenses. The result i s a gradual reversal of the suc-cessional sequence composition and change in peat types (Hebda, 1977). Decompositional Pathways Decomposition of Juncus spp., Carex spp., and Other Sedge- Grass Marsh Plants Although marsh plants are very productive in terms of biomass, the paucity of recognizable stems and leaf fragments in microtome section attests to the e f f i c i e n c y of b a c t e r i a l decay within the marsh environment. Juncus, Carex and Grass Leaves C u t i c l e s , epidermal parenchyma with s i l i c a inclusions, and vascular bundle sheaths are the only recognizable grass and sedge tissues (Plate 1, F i g . 4). These components are randomly oriented in an orange-yellow to tan-brown amorphous 129 m a t e r i a l . No t r a n s i t i o n a l stages of decomposition were ob-served, and decomposition must occur p r i o r to i n c o r p o r a t i o n i n t o the peat s u b s t r a t e . Juncus, Carex and Grass Roots The middle c o r t e x t i s s u e of Juncus i s t h i n n e d by i n i t i a l decomposition ( P l a t e 2, F i g . 4). The p i t h , complete with v a s c u l a r bundles, outer c o r t e x , and epidermal t i s s u e s , re-mains i n t a c t , however. Except f o r outer c o r t e x and epidermal c e l l s , f u r t h e r decomposition t h i n s and e v e n t u a l l y c o n v e r t s the remaining c e l l w a l l s to an amorphous g r a n u l a r y e l l o w - t a n g e l . Secondary c e l l i n c l u s i o n s from the metaxylem c e l l s remain unchanged in the m a t r i x . Ca rex root t i s s u e degrades i n a s i m i l a r manner. Middle cortex t i s s u e s decompose i n i -t i a l l y , and are r e p l a c e d by small g r a n u l a r y e l l o w - t a n g l o -bules ( P l a t e 3, F i g . 4 ) . Both p i t h and e p i d e r m i s show only s l i g h t t h i n n i n g of c e l l w a l l s . E v e n t u a l l y a l l t i s s u e s but the epidermis and c u t i c l e are converted to a g r a n u l a r g e l ( P l a t e 3, F i g . 5). Some endodermal fragments which have f i l l e d w ith secondary c e l l i n c l u s i o n s are r e c o g n i z a b l e . Grass stem fragments, p r i m a r i l y epidermal and c u t i c l e t i s s u e , are a l l t h a t remain. The remainder of the c e l l t i s s u e s most l i k e l y have decomposed p r i o r to i n c o r p o r a t i o n i n t o the peat, as stems remain above ground f o r lengthy p e r i o d s of time. 1 30 Decomposit ion of Ledum qroenlandicum, Kalmia angusti folium,  Vaccinium spp., and Oxycoccus quadripetalus Ericaceous shrubs are adapted to the harsh conditions of raised bog environments. Thin l e n t i c u l a r beds of stems and roots are found, throughout Sphagnum, ericaceous Sphagnum, and sedge-Sphagnum peats. Leaves are best preserved in very wet pure Sphagnum peats. Ericaceous Stems If ericaceous stems are exposed to surface conditions for any length of time, they decompose quickly to form an unstructured orange-brown material which has a fine granular texture. Periderm and rhytidome tissue and primary resin inclusions derived from p i t h and inner phloem are the only recognizable c e l l remains in t h i s g e l . These highly degraded products are incorporated into the peat as small gyttjae pockets. However, should ericaceous stems be swi f t l y incorporated into Sphagnum peat, they decompose slowly, being surrounded by a highly a c i d i c environment, pH 3.0-4.0, which few fungae can t o l e r a t e . If the r e l a t i v e l y thick bark, which also re-s i s t s fungal decay, i s cracked, decomposition i s f a c i l i t a t e d . I n i t i a l l y , secondary xylem elements are thinned with l i t t l e a l t e r a t i o n of other t i s s u e s . These tissues break down com-pl e t e l y to form a yellow-white amorphous material (Plate 10, 1 3 1 F i g . 3). The inner pith region, with primary c e l l i n c l u -sions, i s l e s s decomposed, p a r t i c u l a r l y the medullary sheath (Plate 9, F i g . 3). It decomposes eventually to free the re-sinous globules to the matrix (Plate 10, F i g . 1). The vascu-l a r cambium commonly is converted to a granular yellow-orange material early in the decomposition history as well. The periderm and secondary phloem tissues, which act as storage centers for waste o i l s and tannins, are p a r t i c u l a r l y r e s i s t a n t to decay because of the high tannin concentration (Plate 9, F i g . 4; Plate 10, F i g . 2). Only when inner tissues have been decomposed completely do they collapse, fracture, and form small tissue fragments. Kalmia and Vacc in ium stems have thinner peridermal tissue than Ledum, and are therefore less r e s i s t a n t to at-tack. As a r e s u l t , they are seen less often in section, a l -though they a l l have similar decompositional h i s t o r i e s . Oxycoccus stems are well-preserved, and only minor t h i n -ning of secondary xylem c e l l wall tissues occur (Plate 8, F i g . 2). The extremely wet niche of the plant prevents any degradation. P a r t i a l l y charred ericaceous stems are well preserved. Either the charcoal coating or the w a t e r - f i l l e d depression in which i t accumulates retards the decompositional process. 132 Ericaceous Leaves Ledum, Kalmia, Oxycoccus, and Vaccinium leaves preserve less well than corresponding stem fragments. Although they are seldom eaten by insects, leaves remain on plants several years and become highly degraded before f a l l i n g . The l i t t e r they form i s e a s i l y decomposed or burned in f i r e s . Leaves which are preserved are commonly wedged between Sphagnum layers in wet depressions. Ledum and Kalmia can be preserved with hairs s t i l l at-tached to the underside of leaves (Plate 4, F i g . 3). More commonly, both the lower epidermis and the hairs are decom-posed to a red-brown granular g e l . In the next phase of de-composition, spongy mesophyll c e l l s thin and break down to produce comparable amorphous materials, while palisade c e l l walls thicken with a secondary red-brown material (Plate 8, F i g . 4). When decomposition i s almost complete, the palisade layers are eithe r p a r t i a l l y f i l l e d with clear orange-brown c e l l inclusions and/or orange-brown amorphous material (Plate 8, Fi g . 5). Both c u t i c l e and upper epidermal c e l l s are well preserved at t h i s stage, and often outline former leaf t i s -sue. Vascular bundles decompose at the same time as the lower epidermis. Ledum leaves are large, and are more e a s i l y broken than the more compact ones of Kalmia and Oxycoccus. As a r e s u l t , they are less l i k e l y to be preserved. 133 Ericaceous roots Ericaceous roots are usually well preserved, and show only minor decomposition (Plate 5, F i g . 5). C e l l walls in the secodary xylem often thin, but epidermal c e l l s thicken correspondingly. If decomposition i s extreme, the secondary xylem degrades to amorphous bright yellow g e l . Decomposit ion of Nuphar lutea var. polysepala Although complete l e a f , stem, and root tissues were never observed in eith e r hand sample or microtome section, the appearance of Nuphar pollen led to the recognition of several undecomposed t i s s u e s . These tissues were found f i l -l i n g a large depression in Sphagnum peat, along with Pinus needles and stems, Carex culms and seeds, and large liverwort t h a l l i . Nuphar Leaves Decomposition of leaf tissue is almost complete; the only recognizable c e l l fragments remaining are trichomes (Plate 6, F i g . 5). No intermediate stages in the degrada-ti o n a l h i s t o r y were evident. Nuphar Rootlets Several r o o t l e t s were observed, and are comparable to 134 those seen by Cohen and Spackman ( 1 9 7 7 ) . The xylem, cortex, and endodermis are unaltered, while the phloem and epidermal c e l l walls have been p a r t i a l l y thinned. Decomposition of Rhynchospora alba Rhynchospora i s one of several sedges which grow in w a t e r - f i l l e d depressions within Sphagnum peat. Other spe-c i e s , such as Eriophorum c a l l i t h r i x and Scirpus  subterminalis, may also be present, but were not d i f f e r e n -t i a t e d in thin section. The manner and extent of decomposi-tion that might a f f e c t these sedges would be similar to those of Rhynchospora, considering both plant r e l a t i o n s h i p and sim-i l a r environmental niche. Rhynchospora r o o t l e t s were the only tissues observed microscopically, indicating that the other plant organs had decomposed prior to t h e i r incorpora-tion into Sphagnum peat. Rhynchospora r o o t l e t s In the i n i t i a l stages of decomposition, fungal hyphae attack the outer epidermis, producing small amounts of fine yellow to tan granular material. As yet, l i t t l e a l t e r a t i o n of the c i r c u l a r shape has occurred. Some roo t l e t s remain preserved in t h i s condition (Plate 4, F i g . 2), while the.vas-cular bundle of others is decomposed. Simultaneously, secon-dary c e l l inclusions f i l l the endodermis of these rootlets with golden to dark brown amorphous material. If t h i s does 135 not occur, the c i r c u l a r root is contorted by the growth of other roots and is f i l l e d e n t i r e l y by fungal hyphae. As de-composition continues, the cortex region i s converted to an amorphous yellow-brown material, leaving just an endodermal ring. Other s p a t i a l l y related rootlets have thickened brown c e l l walls, and show no evidence of degradation. Decomposition of Pinus contorta Although stumps of t h i s species are frequently observed in Sphagnum and ericaceous Sphagnum peat, stem and root t i s -sues are not common in th i s peat. Needles are abundant in both f i r e horizons, where they appear as semifusinite s h e l l s , and in wet depressions, where they are well preserved. Pinus Stem and Branch Fragments If Pinus stem and branch fragments remain exposed at the surface for any length of time, the secondary xylem tissue i s broken down by moulds and fungi. This process leaves only the bark (periderm and outer phloem complex) unaltered. These remaining tissues become dry and fracture, and are i n -corporated into the peat as small rhytidome tissue fragments. If fragments become enclosed in Sphagnum or f a l l into w a t e r - f i l l e d depressions, preservation i s more l i k e l y to occur. If cracks in the rhytidome (outer bark) continue through the periderm to secondary phloem t i s s u e , the cambial 136 layer undergoes rapid decomposition to an orange-brown amor-phous material. Bark elements are then able to fracture fur-ther, and separate e n t i r e l y from secondary xylem t i s s u e s . A l l walls of tracheids, vessels, and parenchyma thin appre-c i a b l y following t h i s early phase of decomposition. If degradation continues, pockets of amorphous l i g h t tan-brown material replace c e l l wall structure completely (Plate 10, F i g s . 4,5). These pockets continue to grow u n t i l a l l i n t e r n a l structure except the p i t h i s converted to a gel. During t h i s destructional phase, irregular brown secondary c e l l inclusions are added, together with small round red p r i -mary c e l l inclusions already present in the p i t h . Secondary phloem tissues also accumulate these brown c e l l i n clusions, which may be a l t e r e d tannins. Pinus needles Pinus needles which have accumulated in w a t e r - f i l l e d depressions such as Nuphar hollows are well preserved. The hypodermis, epidermis and thick c u t i c l e show no a l t e r a t i o n (Plate 9, Fig.1 ). Inner bundles of vascular and transfusion tissue exhibit thinning of the c e l l walls. This continues u n t i l the c e l l s collapse and small round c e l l i nclusions are released. Material produced as a result of decomposition accumulates in the mesophyll as either thickened c e l l walls or p a r t i a l secondary c e l l inclusions (Plate 9, F i g . 2). Nei-ther resin ducts nor endodermis show any appreciable d i f -137 ference from modern tissue. Pinus Roots Due to a thick periderm and secondary phloem, only t h i n -ning of the secondary xylem elements has occurred. Other-wise, no degradation has occurred in the microtome section studied. Decomposition of Sphagnum spp. Sphagnum i s the dominant genus in late successional stages of a raised bog. As a bryophyte, i t contains no com-plex vascular tissues, and thus i s l i m i t e d in s i z e . Sphagnum i s well adapted to moist environments of low nutrient influx. The rhizoids of this plant are able to exchange hydrogen ions for mineral cations (Moore and Bellamy, 1974). As a re s u l t , the pH of the environment i s extremely a c i d i c , pH 2.9-3.5, and when combined with the e f f i c i e n t water-holding capacity of this plant, creates a niche which favours the preservation of plant t i s s u e . Sphagnum Stems I n i t i a l compression of stem tissue occurs just beneath the surface of the peat, where i t takes on a horizontal a t t i -tude. No c e l l wall fracturing occurs from th i s early compac-tion (Plate 7, F i g . 4). Stem t i p s exposed at the surface in 1 3 8 d r y e n v i r o n m e n t s a r e browner i n c o l o r . C e l l w a l l s of stem t i s s u e t h i n s l i g h t l y as s m a l l amounts o f l i g h t y e l l o w amor-phous m a t e r i a l a r e p r o d u c e d . A f t e r t h i s s t a g e , however, t i s -s u e s become d a r k e r t a n t o l i g h t brown as c e l l w a l l s f i l l w i t h an o r a n g e - b r o w n g r a n u l a r g e l . I m p r e g n a t i o n o f t h e s e s e c o n -d a r y c e l l i n c l u s i o n s h a l t s any f u r t h e r d e g e n e r a t i o n . Sphagnum L e a v e s Sphagnum l e a f c e l l w a l l s t h i n a n d f r a c t u r e f a s t e r t h a n stem c o m p o n e n t s . A l t h o u g h f u n g i i n i t i a l l y a v o i d t h e a c i d i c m i c r o e n v i r o n m e n t o f Sphagnum, hyphae e v e n t u a l l y s t a r t decom-p o s i n g l e a f t i s s u e s . F i n e g r a n u l a r r e d - b r o w n m a t e r i a l i s p r o d u c e d t h r o u g h o u t t h e m a t r i x as c e l l w a l l s decompose ( P l a t e 7, F i g . 5 ) . The f i n a l ' p r o d u c t i s a few c e l l f r a g m e n t s s c a t -t e r e d t h r o u g h o u t a red-brown g r a n u l a r g e l . The g r a d u a l i n c r e a s e i n c e l l i n c l u s i o n s w i t h i n stem t i s s u e c o i n c i d e s w i t h t h e d e c o m p o s i t i o n o f l e a f m a t e r i a l . S u c h p r o c e s s e s a r e p o s s i b l y l i n k e d t h r o u g h t h e m i g r a t i o n of s p e c i f i c d e c o m p o s i t i o n a l l y r e s i s t a n t f l u i d s . D e c o m p o s i t i o n of O t h e r P l a n t T i s s u e s Typha l a t i f o l i a , w h i c h i s a component o f s e d g e - g r a s s p e a t , and D r o s e r a r o t u n d i f o l i a , common t o Sphagnum p e a t , were no t r e c o g n i z e d i n m i c r o t o m e s e c t i o n . A l t h o u g h t h e d e c o m p o s i -t i o n of b o t h p l a n t s i s n e a r l y c o m p l e t e a t t h e p e a t s u r f a c e , 139 the root and culm of Typha should be preserved. The lower density of these plants, combined with the small sample siz e , may account for t h i s anomaly. 1 40 DISCUSSION AND CONCLUSIONS Peat Types Six of the ten peat types distinguished have accumulated in marsh habitats. These early peats, represented by sedge-clay, sedge-grass, sedge-wood and gyttjae b i o f a c i e s , have been influenced to a large extent by the depositional en-vironment. V a r i a b i l i t y between depositional settings has produced d i f f e r e n t generic compositions. Petrographic char-a c t e r i s t i c s (Table 1) and decompositional pathways within i n d i v i d u a l peat facies are therefore unique. Sedge-clay and gyttja peats are highly decomposed as a result of periodic exposure to oxygenated waters of near neu-t r a l pH. The advanced state of decomposition is observed petrographically by a low r a t i o of framework matrix and the absence of c e l l fragments and i n c l u s i o n s . The presence of large amounts of fine sediment a t t e s t to the hypauthoch-thonous o r i g i n for much of the organic matrix and explain the granular appearance of these peats. Marine and brackish sedge-grass peats exhibit s i m i l a r c h a r a c t e r i s t i c s , but are r e l a t i v e l y more fibrous and better preserved. In the t r a n s i -tion to freshwater sedge-grass peats, increasingly a c i d i c environments r e s t r i c t both b a c t e r i a l and fungal a c t i v i t y , allowing better preservation and correspondingly higher r a t i o s of framework to matrix. Increasing numbers of c e l l fragments and inclusions also occur. Analogous t r a n s i t i o n s T A B L E 1: SUMMARY OF THE C H A R A C T E R I S T I C S OF THE V A R I O U S P E A T T Y P E S P e a t T y p e D o m 1 n a n t P1 a n t s C o l o r T e x t u r e R a t i o F r a m e w o r k t o M a t r i x C e 1 1 s a n d C e l 1 F r a g m e n t s C e l 1 I n c l u s 1 o n s s e d g e - c l a y p e a t g y t t j a p e a t s a 1 t w a t e r s e d g e - g r a s s b r a c k 1 s h s e d g e - g r a s s f r e s h w a t e r s e d g e - g r a s s s e d g e - w o o d s e d g e S p h a g n u m N u p h a r  S p h a g n u m E r i c a c e o u s S p h a g n u m G r a m 1 n e a e E q u 1 s e t u m E 1 y m u s T r 1 q 1 o c h 1 n  D 1 s t i c h l I s  S a 1 1 c o r n 1 a S c i r p u s om. C a r e x 1 y n ,  T y p h a 1 a t 1 f o l 1 a  E 1 e o c h a r 1 s C a 1 a m o q r o s t 1 s  C a r e x c o s t .  T y p h a 1 a t 1 f o l 1 a  E q u 1 s e t u m P o p u 1 u s  C a r e x  B e t u ! a  P 1 c e a S p h a g n u m  R h y n c h o s p o r a  O x y c o c c u s  E r 1 o p h o r u m N u p h a r 1 1 v e r w o r t S p h a g n u m  O x y c o c c u s  Ka1m i a L e d u m  O x y c o c c u s  Ka1m1 a  S p h a g n u m P 1 n u s t a n g r e y t o 1 1 g h t b r o w n y e 11ow b r o w n t o b l a c k b r o w n t o d a r k b r o w n y e 11ow b r o w n t o b r o w n y e l l o w b r o w n t o g o l d y e l l o w b r o w n t o d a r k b r o w n y e 11ow t o r e d b r o w n g o 1 d e n o r a n g e g o l d e n y e 11ow g r a n u l a r t o f r a g m e n t a 1 f I n e g r a n u l a r f i b r o u s t o f 1 n e g r a n u l a r f i b r o u s t o f i n e g r a n u l a r f i b r o u s t o f 1 n e g r a n u 1 a r f i b r o u s t o f r a g m e n t a 1 1 ow 1 ow 1 ow f 1 b r o u s g r a n u 1 a r f 1 b r o u s r e d y e l l o w t o f i b r o u s t o r e d b r o w n f r a g m e n t a 1 1 ow t o m o d e r a t e m o d e r a t e h i g h h i g h 1 ow h 1 g h v a r 1 a b 1 e , m o d e r a t e f e w common t o a b u n d a n t a b u n d a n t common f e w a b u n d a n t f e w f e w f e w f e w f e w f e w f e w t o common a b u n d a n t T a b l e 1 ( c o n t ' d ) A m o r p h o u s D e b r i s P e a t T y p e F i n e G r a n u l a r F o r a m 1 n 1 f e r a D1 a t o m s F u n g a 1 D e b r 1 s P o l l e n C h a r c o a l o r F u s i n i t e M1 n e r a 1 M a t t e r s e d g e - c l a y h i g h t o a b u n d a n t p e a t m o d e r a t e g y t t j a p e a t s a l t w a t e r common s e d g e - g r a s s h i g h h i g h c h 1 1 1 n o u s common r a r e common commc a g g l u t i n a t e d c o n c e n t r i c r a r e some common S a l I x A 1 n u s r a r e a 1 1 o c h t h o n o u s r a r e a 1 1 o c h t h o n o u s Gram 1 n e a e P 1 n u s A 1 n u s  S a l I x C h e n o p o d 1 a c e a e C y p e r a c e a e a 1 1 o c h t h o n o u s f e w b r a c k i s h m o d e r a t e s e d g e - g r a s s f r e s h w a t e r m o d e r a t e s e d g e - g r a s s t o l o w a g g l u t i n a t e d common f e w c h t 11 n o u s f e w f e w c h 1 1 1 n o u s f e w f e w C y p e r a c e a e v e r y l i t t l e f e w g r e a t e r t h a n some G r a m 1 n e a e C y p e r a c e a e l e s s t h a n Gram 1 n e a e s e d g e - w o o d r a r e r a r e 1 ow a b s e n t f e w common a b s e n t s e d g e S p h a g n u m 1 ow a b s e n t a b s e n t C y p e r a c e a e S p h a g n u m E r 1 c a c e a e a b s e n t N u p h a r m o d e r a t e f e w f e w N u p h a r a n d C y p e r a c e a e a b s e n t S p h a g n u m 1 ow a b s e n t a b s e n t S p h a g n u m E r I c a c e a e P 1 n u s a b s e n t E r i c a c e o u s v a r i a b l e S p h a g n u m m o d e r a t e f e w a b s e n t v a r 1 a b l e m o d e r a t e S p h a g n u m E r I c a c e a e P i n u s a b s e n t 143 o c c u r i n t h e c o m p o s i t i o n of m i c r o f a u n a and p o l l e n a s s e m b l a g e s and i n t h e amount of c h a r c o a l and m i n e r a l m a t t e r p r e s e n t . Sedge-wood p e a t s o r i g i n a t e f r o m f r e s h w a t e r f a c i e s m a r g i n a l t o n a t u r a l l e v e e s . L a r g e r a n o u n t s o f wood and s e d i m e n t i n t h e s e p e a t s can be e x p l a i n e d by t h e d e p o s i t i o n a l s e t t i n g ; t h e i n -c r e a s e d p r e s e r v a t i o n o f t h e s e p e a t s c a n n o t . I t i s s u g g e s t e d , however, t h a t humic a c i d s f r o m m a r g i n a l p e a t f a c i e s n e u t r a -l i z e t h e e f f e c t s o f h i g h l y o x y g e n a t e d w a t e r s d u r i n g o c c a -s i o n a l f l o o d e v e n t s . The r e m a i n i n g f o u r p e a t b i o f a c i e s , sedge-Sphagnum, Nuphar, Sphagnum and e r i c a c e o u s Sphagnum, have d e v e l o p e d i n bog h a b i t a t s . U n l i k e marsh p e a t s , bog b i o f a c i e s have been o n l y s l i g h t l y i n f l u e n c e d by d e p o s i t i o n a l e n v i r o n m e n t s . I n -s t e a d , t h e s e b i o f a c i e s m o d i f y t h e e n v i r o n m e n t s u f f i c i e n t l y t o d e t e r m i n e a p r e d i c t a b l e s u c c e s s i o n a l s e q u e n c e . As a r e s u l t , t h e s e p e a t b i o f a c i e s have s i m i l a r g e n e r i c c o m p o s i t i o n s and p e t r o g r a p h i c c o m p o s i t i o n s w h e r e v e r t h e y a r e p r e s e n t . S m a l l d i f f e r e n c e s do, however, r e s u l t f r o m c l i m a t i c v a r i a t i o n . Nuphar p e a t s , f o r example, a r e f o u n d o n l y i n d e l t a p l a i n p e a t s where w a t e r t a b l e s a r e l o w e r e d s u f f i c i e n t l y i n summer t o a l l o w d e e p b u r n i n g ( S t y a n and B u s t i n , 1981). Sphagnum and sedge-Sphagnum b i o f a c i e s r e p r e s e n t wet n i c h e s w i t h i n t h e bog e n v i r o n m e n t . T h e s e p e a t s a r e commonly so w e l l p r e s e r v e d b e c a u s e of t h e wet and a c i d i c c o n d i t i o n s p r o d u c e d by Sphagnum t h a t a s s o c i a t e d g e n e r a l i k e O x y c o c c u s , R h y n c h o s p o r a , C a r e x and E r i o p h o r u m a r e e a s i l y i d e n t i f i e d . I n 144 contrast, ericaceous Sphagnum peats have accumulated in drier areas of the bog. Consequently, they contain larger amounts of charcoal, fungal s c l e r o t i a and are more decomposed than Sphagnum peats. A lower r a t i o of framework to matrix, fewer c e l l fragments, and increased amorphous material in these peats r e f l e c t the differences. Nuphar peats consist of both autochthonous and a l l o c h -thonous plant components deposited together in w a t e r - f i l l e d depressions. Preservation varies according to the o r i g i n of the component. Material remaining exposed on the peat sur-face for some time before accumulating in the pond i s highly a l t e r e d in comparison to autochthonous t i s s u e . A granular peat with abundant c e l l fragments but a low r a t i o of frame-work to matrix r e s u l t s . Decomposition of in d i v i d u a l plant tissues in a variety of d i f f e r e n t environments produces a diverse range of maceral precursors (Tables 2 and 3). Although the prediction of ma-c e r a l precursors from observing decompositional pathways in modern environments is hypothetical, the c r i t e r i o n for the formation of s p e c i f i c coal macerals has been established (Teichmuller, 1975; Cohen and Spackman, 1980, and others). T A B L E 2: SOME P L A N T T I S S U E S AND THE P R O B A B L E COAL M A C E R A L S ( M A C E R A L G R O U P S ) D E R I V E D FROM THEM V i t r i n l t e ' I n e r t l n l t e E x i M t e M l c r l n l t e O x y f u s i n i t e P l a n t O r g a n T e l l n i t e T e l o c o l 1 1 n i t e M a c r l n i t e R e s i n i t e C u t l n l t e P i n u s c o n t o r t a R o o t P 1 n u s c o n t o r t a S t e m c e 1 1 w a 1 1 s o f o u t e r c o r t e x e p i d e r m i s a n d e n d o d e r m 1 s c e l 1 w a l 1 s o f e p i d e r m i s , p h l o e m a n d [ p i t h ] c a p c e l I s ( x y 1 em) x y l e m p h l o e m p e r l c u l e I n n e r c o r t e x c e l 1 c o n t e n t s c e l 1 w a l 1 s o f x y l e m . c a m b i u m c e l 1 c o n t e n t s a f t e r f i r e s a n d p r o l o n g e d e x p o s u r e p r i o r t o b u r i a l r e d b r o w n c e l l I n c l u s i o n s o f p e r i d e r m a n d s e c o n d -a r y p h l o e m s p h e r 1 c a 1 c e l 1 o f p i t h - r e d a n d o r a n g e r e d s e c o n d a r y L e d u m g r o e n l a n d l c u m R o o t c e 1 1 w a 1 1 s e p i d e r m i s , e n d o d e r m 1 s o f c e l 1 w a l I s x y l e m a n d c o r t e x o f r e d b r o w n p e r i d e r m , c e l l i n c l u s i o n s w / c L e d u m q r o e n 1 a n d 1 cum S t e m c e 1 1 w a 1 1 s o f p h l o e m , e p i d e r m i s a n d [ p i t h ] c e l 1 w a 1 1 s o f x y l e m a n d c a m b i u m a f t e r f i r e s a n d p r o l o n g e d e x p o s u r e p r i o r t o b u r i a l r e d b r o w n p e r i d e r m c e l l I n c l u s i o n s w / c r o u n d e d r e d r e d / b r o w n 1n t h e p i t h a n d s e c o n d -a r y p h l o e m c e l l s S p h a g n u m  c a p i 1 1 a c e u m L e a f c e l 1 w a l 1 s c e l 1 c o n t e n t s S p h a g n u m  c a p i 1 1 a c e u m S tern c e l 1 w a ! 1 s c e l 1 c o n t e n t s s e c o n d a r y t a n b r o w n I n c l u s i o n s i n c e l 1 w a l 1 s L e d u m g r o e n l a n d l c u m l e a f c e 1 1 w a 1 1 s o f p a 1 1 1 s a d e a n d u p p e r e p i d e r m i s c e l 1 w a l 1 s o f m e s o p h y l 1 , p h i o e m a n d c a m b i u m c e l 1 c o n t e n t s a f t e r f i r e s a n d p r o l o n g e d e x p o s u r e p r i o r t o b u r i a l s e c o n d a r y r e d - b r o w n I n c l u s i o n s 1n x y l e m a n d p a 1 1 1 s a d e p a r e n c h y m a c u t i c l e P i n u s c o n t o r t a n e e d l e c e l 1 w a 1 1 s o f e p i d e r m i s , h y p o d e r m i s a n d m e s o p h y 1 1 r e s i n d u c t s c e 1 1 w a 1 1 s o f x y l e m , p h l o e m t r a n s f u s i o n t i s s u e a f t e r f i r e s a n d p r o l o n g e d e x p o s u r e s p r i o r t o b u r i a l s e c o n d a r y y e l l o w b r o w n i n c l u s i o n s i n m e s o p h y l 1 a n d r e s i n d u c t s c u t i c l e C a r e x s p p . R o o t c e 1 1 w a 1 1 s o f o u t e r c o r t e x a n d e p i d e r m i s c e 1 1 w a 1 1 s o f p i t h , i n n e r & m i d d l e c o r t e x , x y l e m , p h l o e m a n d e n d o d e r m i s c e l 1 c o n t e n t s R h y n c h o s p o r a c e l 1 wa l 1 s o f c e l 1 w a l 1 s o f p i t h R o o t e n d o d e r m i s a n d x y l e m , p h l o e m i n n e r o u t e r c o r t e x a n d m i d d l e c o r t e x e p i d e r m i s • J u n c u s s p p . c e l l w a l 1 s o f c e 1 1 w a 1 1 s o f R o o t e n d o d e r m i s p i t h , x y l e m , p h l o e m ep1 d e r m i s i n n e r a n d m i d d l e o u t e r c o r t e x c o r t e x N u p h a r s p . c e 1 1 w a 1 1 s o f c e 1 1 w a 1 1 s o f L e a f e p i d e r m i s p a l i s a d e , m e s o p h y l l a n d a s t r o s c l e r e i d s a n d c e l 1 c o n t e n t s O x y c o c c u s s p p . c e l 1 w a l 1 s o f c e l 1 w a l I s o f R o o t e p i d e r m i s , e n d o d e r m i s x y 1 em O x y c o c c u s s p . c e l 1 w a l 1 s o f c e l 1 w a l 1 s o f S t e m e p i d e r m i s , p h l o e m c a m b i u m a n d a n d p i t h x y 1 em O x y c o c c u s s p . c e 1 1 w a 1 1 s o f c e l 1 w a l 1 s o f L e a f ep1 d e r m i s , p a 1 i s a d e m e s o p h y l 1 b r o w n s e c o n d a r y c e l 1 I n c l u s i o n s o f e n d o d e r m 1 s r e d s e c o n d a r y c e l l i n c l u s i o n s o f t h e e n d o d e r m i s a n d i n t h e c o r t e x h y p o d e r m i s c u t i c l e a n d t r i c h o m e s r e d c 1 r c u 1 a r c e l l i n c l u s i o n s i n c o r t e x r o u n d r e d c e 1 1 i n c l u s i o n s i n p i t h a n d s e c o n d a r y x y l e m s e c o n d a r y i n c l u s i o n s c u t i c l e i n p a 1 1 s a d e p a r e n c h y m a - s m a l l , I r r e g u l a r b r o w n T A B L E 3: PEAT T Y P E S AND A S S O C I A T E D COAL M A C E R A L S E r i c a c e o u s F r e s h w a t e r P e a t T y p e G y t t j a P e a t s S p h a g n u m P e a t s S p h a g n u m P e a t s N u p h a r P e a t s S e d g e - G r a s s P e a t s dom i n a n t c o a 1 ' m a c e r a 1 s m i n o r c o a l m a c e r a 1 s d o m 1 n a n t m 1 c r o l 1 t h o t y p e s 1 l p t o d e t r ( n i t e a 1g i n i t e c u t i n 1 t e d e s m o c o 1 1 i n i t e i n e r t o d e t r i n i t e m i c r i n i t e 1 i p t i t e a n d t h i n c l a r i t e b a n d s s u b e r i n i t e t e l i n i t e t e l o c o l 1 i n i t e p y r o f u s i n i t e d e s m o c o 1 1 i n i t e o x y f u s i n i t e c u t i n i t e s c 1 e r o t i n i t e r e s i n i t e s p o r o n 1 t e v i t r i t e w i t h b a n d s o f c l a r i t e 1 e n s e s o f l i p t i t e a n d d u r i t e t e l i n i t e ' r e s i n i t e t e l e n i t e c u t 1 n 1 t e c u t 1 n i t e t e l o c o 1 1 i n i t e v 1 t r i t e 1 i p t o d e t r i n i t e m a c r i n i t e s c 1 e r o t i n i t e c u t i n i t e s u b e r i n i t e d e s m o c o 1 1 i n i t e s c l e r o t i n i t e 1 i p t i t e a n d c l a r i t e t e l o c o l 1 i n i t e t e l i n i t e , p y r o f u s i n i t e d e s m o c o l 1 i n i t e c e r e n 1 t e c l a r i t e w i t h t h 1 n 1 n t e r b a n d e d I n e r t i n i t e a n d v i t r 1 t B r a c k i s h W a t e r M a r i n e o r P e a t T y p e S e d g e - W o o d P e a t s N a t u r a l L e v e e s S e d g e - G r a s s P e a t s S a l t w a t e r P e a t s d o m 1 n a n t c o a 1 m a c e r a 1 s s u b e r 1 n 1 t e t e l o c o 1 1 1 n 1 t e c u t 1 n 1 t e m a c r I n i t e o x y f u s l n l t e p y r o f u s i n i t e c e r e n 1 t e t e l o c o l 1 i n i t e d e s m o c o ! 1 i n i t e c u t i n i t e c e r e n 1 t e d e s m o c o l 1 I n i t e c u t 1 n 1 t e m i n o r c o a l m a c e r a 1 s t e l i n 1 t e o x y f u s i n i t e s u b e r i n i t e d e s m o c o l 1 i n i t e v 1 t r o d e t r i n i t e p y r o f u s 1 n 1 t e o x y f u s I n i t e m a c r i n i t e m a c r I n i t e s c l e r o t I n i t e h u m o d e t r I n i t e 1 i p t o d e t r i n i t e s p o r o n 1 t e a 1 g 1 n i t e d o m i n a n t v t t r l t e b a n d s m 1 c r o 1 1 t h o t y b e s w i t h d u r i t e a n d m1 n o r c l a r i t e d u r 1 t e a n d v i t r 1 n e r t 1 t e 1 n t e r 1 am 1 n a t e d c u t l n i c c l a r i t e c u t i n l c c l a r i t e a n d i n t e r l a m i n a t e d some d u r i t e d u r 1 t e 149 Maceral Format ion The formation of p a r t i c u l a r coal macerals is a function of the composition and structure of the i n i t i a l plant ma-t e r i a l and subsequent biochemical degradation and organic metamorphism ( F l a i g , 1968). Biochemical degradation i s con-t r o l l e d both by the climate and by the physical parameters of the peat-forming environment, whereas organic metamorphism i s regulated by temperature and, to a lesser extent, pressure within the coal-forming s t r a t a . The complexity of these pro-cesses can be reduced through the r e a l i z a t i o n that the pro-ducts of biochemical degradation are the reactants or con-t r o l l i n g factors in the transformations of organic metamor-phism. If the reactants are known, then i t becomes possible to predict a series of a l t e r n a t i v e products for d i f f e r e n t pressures and temperatures. As the i n i t i a l compositions and structures have already been resolved for most plant groups (Robinson, 1963; Bonner, 1976; Northcote, 1977), i t remains to understand the pro-cesses of biochemical degradation. This can be done through either geochemical analysis or petrographic examination of a wide variety of peat-forming environments. In the peat-forming environments described in t h i s study, the i n i t i a l stages of formation are dominated by sedge-grass peats. The composition of the community i s mar-kedly d i f f e r e n t in each area, in response to widely varying 1 50 p h y s i o - c h e m i c a l p a r a m e t e r s . As t h e s e p a r a m e t e r s a l s o c o n t r o l d e c o m p o s i t i o n a l r a t e s and p a t h w a y s , a wide v a r i e t y of m a c e r a l p r e c u r s o r s c a n be p r e d i c t e d ( T a b l e 3 ) . When Sphagnum-dominated s t a g e s s u c c e e d t h e s e d g e - g r a s s p e a t s , t h e p l a n t community i s no l o n g e r t o t a l l y r e g u l a t e d by e x t e r n a l g e o c h e m i c a l p a r a m e t e r s . I n s t e a d , s p e c i e s " c o m p o s i -t i o n and p l a n t s u c c e s s i o n m o d i f y t h e e n v i r o n m e n t . F i r e and f l o o d e v e n t s may c a u s e s i g n i f i c a n t l o c a l v a r i a t i o n s i n t h e s u c c e s s i o n a l s e q u e n c e , but o n l y c l i m a t e and s o i l p r o c e s s e s c a n i n f l u e n c e l o n g - t e r m v a r i a t i o n . As much of p l a n t s u c c e s s i o n and t h e d e c o m p o s i t i o n a l pathways a r e a n a l o g o u s i n t h e L u l u I s l a n d and P i t t Meadows bogs, t h e m a c e r a l c o m p o s i t i o n i s s i m i l a r . Amounts of s p e c i f -i c m a c e r a l s d i f f e r s l i g h t l y b e c a u s e o f l a t e r a l f a c i e s c h a n g e s . The b a s a l s e d g e - g r a s s p e a t s a r e d i f f e r e n t between d e p o s i t s , however. V a r i a t i o n s i n b o t h s p e c i e s c o m p o s i t i o n and d e c o m p o s i t i o n a l p a thways c a u s e t h e s e , p e a t s t o show d i s -t i n c t d i f f e r e n c e s i n t h e t y p e s and d i s t r i b u t i o n of m a c e r a l s . C o r r e s p o n d i n g l y , Boundary Bay s e d g e - g r a s s p e a t s show marked c h a n g e s i n m a c e r a l f a b r i c i n c o m p a r i s o n t o t h e o t h e r d e p o s -i t s , a s a r e s u l t o f i n i t i a l s p e c i e s c o m p o s i t i o n and l a t e r a l t e r a t i o n by m a r i n e w a t e r s . P e a t s a t B o u ndary Bay r e p r e s e n t t h e e a r l i e s t s t a g e s i n t h e c o l o n i z a t i o n of r e c e n t d e l t a s e d i m e n t s ( S h e p p e r d , 1981). An a b u n d a n c e of c h e n o p o d p o l l e n a t t h e b a s e o f t h e p e a t c o n -151 f i r m s i t s o r i g i n f r o m s a l t w a ter marsh s p e c i e s . T h e s e p l a n t s a r e r e p l a c e d w i t h b r a c k i s h w ater and e v e n t u a l l y f r e s h w a t e r marsh s p e c i e s a s t h e p e a t b u i l d s above t i d a l i n f l u e n c e . When t h i s o c c u r s , n u t r i e n t s u p p l i e s a r e r e d u c e d , and t h e r a t e of p e a t a c c u m u l a t i o n f a l l s below t h e r a t e o f s e d i m e n t compac-t i o n . Not o n l y d o e s t h e c o m p o s i t i o n o f t h e p e a t a g a i n a c -q u i r e s a l t m a r s h a f f i n i t y , b ut t h e e n t i r e s e c t i o n i s a l t e r e d by m a r i n e w a t e r s . Near n e u t r a l pH p r o d u c e s an e n v i r o n m e n t c o n d u c i v e t o b a c t e r i a l g r o w t h , and d e c o m p o s i t i o n r a t e s o f p l a n t m a t e r i a l a r e h i g h . M i c r o t o m e s e c t i o n s f r o m t h e s e h i g h l y a l t e r e d p e a t s r e v e a l a b u n d a n t y e l l o w - o r a n g e amorphous m a t e r i a l . A s m a l l number of s e d g e an d g r a s s r o o t s f l o a t w i t h i n t h i s s t r u c t u r e -l e s s m a t r i x . R a r e l y , sedge and' g r a s s stems and d e g r a d e d l e a f f r a g m e n t s a r e r e c o g n i z a b l e . M a r i n e - d e r i v e d p l a n t d e b r i s , l a r g e l y a l g a l , f o r m s t h e b a s e of t h e d e p o s i t . B e c a u s e of t h e i n i t i a l l a c k o f l i g n i n and c o r r e s p o n d i n g l y h i g h c o n c e n t r a t i o n of c e l l u l o s e i n t h i s p e a t , t h e m a c e r a l s f o r m e d a r e p r i m a r i l y h u m o d e t r i n i t e and u l t i m a t e l y d e s m o c o l l i n i t e . S c a t t e r e d t h r o u g h o u t i n t h i n l e n s e s a r e t h e r e m a i n s of c u t i c l e s ( c u t i n i t e ) , f i n e d e t r i t a l h y d r o g e n - r i c h c e l l masses ( l i p t o d e t r i n i t e ) , and s p o r e - r i c h a r e a s ( s p o r i n i t e ) . The h i g h c o n c e n t r a t i o n s o f p a r a f f i n s a s s o c i a t e d w i t h C y p e r a c e a e a r e t h e m a c e r a l p r e c u r s o r s o f c e r e n i t e , w h i c h o f t e n i s s p a t i a l l y r e l a t e d t o c u t i n i t e . The s m a l l amounts of r o o t and stem t i s s u e o f s e d g e s and g r a s s e s w h i c h a r e p r e s e r v e d f o r m i n t e r -s p e r s e d b l e b s o f t e l e n i t e . P y r o f u s i n i t e , s c l e r o t i n i t e , and 152 m a c r i n i t e a r e r a r e . In t h e t r a n s i t i o n f r o m t h e m a r i n e t o t h e n o n - m a r i n e p o r -t i o n of t h e p e a t , t h e r e i s an a c c o m p a n y i n g g r a d u a l change i n t h e m a c e r a l c o m p o s i t i o n . D e s m o c o l l i n i t e i s c o n t i n u a l l y r e -p l a c e d u p s e c t i o n by i n t e r l a m i n a t e d l e n s e s o f m a c r i n i t e and o x y f u s i n i t e and t h i n f r a g m e n t a l bands o f p y r o f u s i n i t e . T h i n p l a t e l e t s o f l i p t o d e t r i n i t e , c u t i n i t e , and a s s o c i a t e d c e r e n i t e , w h i c h a r e not o x i d i z e d d u r i n g p e r i o d i c d e s i c c a t i o n , o c c u r r a n d o m l y t h r o u g h o u t t h e f a b r i c . T i n y s c l e r o t i n i t e f r a g m e n t s a r e a s s o c i a t e d w i t h b o t h o x y f u s i n i t e and p y r o f u -s i n i t e . The t r e n d t o w a r d i n c r e a s i n g i n e r t i n i t e s r e v e r s e s i t s e l f i n t h e u p p e r m a r i n e p o r t i o n o f t h e p e a t , and m a c e r a l p r e c u r -s o r s a n a l o g o u s t o t h o s e a t t h e b a s e a g a i n a t t a i n d o m inance. S e d g e - g r a s s components n e a r t h e b a s e o f t h e L u l u I s l a n d p e a t a l s o have been i n f l u e n c e d by b r a c k i s h w a t e r , as t h e p r e -s e n c e of c o n c e n t r i c d i a t o m s , a g g l u t i n a t e d f o r a m i n i f e r a , T r i q l o c h i n r h i z o m e s , and numerous d i n o f l a g e l l a t e c y s t s i n d i -c a t e . P l a n t c o m m u n i t i e s s i m i l a r t o t h o s e a t B o u n d a r y Bay a r e l i k e l y t o have been p r e s e n t , b u t no c h e n o p o d p o l l e n was ob-s e r v e d , and no s a l t marsh d e v e l o p m e n t i s i n d i c a t e d . In m i c -rotome s e c t i o n , l e s s m a t r i x a t t e s t s t o b e t t e r p r e s e r v a t i o n . As a r e s u l t , m a c e r a l c o m p o s i t i o n c o n s i s t s o f a m i x t u r e of d e s m o c o l l i n i t e , t e l l i n i t e , and m i n o r m a c r i n i t e . The l a t t e r i n c r e a s e s u p s e c t i o n as t h e marsh becomes e m e r g e n t and i s de-153 s i c c a t e d f o r l o n g e r p e r i o d s o f t i m e . A s i m i l a r i n c r e a s e i n o x y f u s i n i t e and p y r o f u s i n i t e a c c o m p a n i e s t h i s t r a n s i t i o n . T h i n p l a t e l e t s o f c u t i n i t e w i t h a s s o c i a t e d b l e b s o f c e r e n i t e , f i n e g r a i n s o f i n e r t o d e t r i n i t e , and l i p t o d e t r i n i t e a r e p e r v a -s i v e and c o n t r i b u t e t o a b a n d e d t e x t u r e . As f r e s h w a t e r s e d g e - g r a s s p e a t s s u c c e e d t h o s e of b r a c k -i s h w a t e r , a r e a l e x p o s u r e i n c r e a s e s and m a r s h e s may d r y o u t f o r e x t e n d e d p e r i o d s of t i m e d u r i n g t h e y e a r . M a c r i n i t e , s c l e r o t i n i t e ^ and t e l o c o l l i n i t e f u r t h e r i n c r e a s e a t t h e ex-p e n s e of d e s m o c o l l i n i t e i n d r i e r a r e a s , w h i l e t e l e n i t e and a l g i n i t e do so i n t h e w e t t e r d e p r e s s i o n s . M a r g i n a l t o na-t u r a l l e v e e s , r a p i d i n c r e a s e s i n t h e amounts o f b o t h p y r o f u -s i n i t e a n d o x y f u s i n i t e o c c u r , a s t h e s e a r e a r e a s of h i g h e r e l e v a t i o n . S i m i l a r m a c e r a l c o m p o s i t i o n s a r e e x p e c t e d above c r e v a s s e and f i r e s p l a y s u n t i l t h e n a t u r a l p e a t s u c c e s s i o n a l s e q u e n c e i s r e a t t a i n e d . P y r o f u s i n i t e o c c u r s more f r e q u e n t l y as t h i n m i c r o b a n d s . T h e s e a r e u n d e r l a i n by p o c k e t s o f t e l l o c o l l i n i t e , d e s m o c o l -l i n i t e , a n d much s c l e r i n i t e . P o c k e t s of d e t r i t a l wood p r o -duce t h i c k e r bands of t e l e n i t e a n d p a t c h e s o f i n t e r n a l t e l o -c o l l i n i t e . S u b e r i n i t e i s a s s o c i a t e d w i t h t h e bands, as b o r -d e r i n g s t r i p s o r as d i s s e m i n a t e d f i n e g r a n u l e s . Sphagnum c o l o n i s a t i o n r e d u c e s b o t h d e s i c c a t i o n and de-g r a d a t i o n by b a c t e r i a . In t h e t r a n s i t i o n t o e r i c a c e o u s Sphagnum p e a t , g r a s s and sedge components a r e b e t t e r p r e -15 4 s e r v e d and f o r m t e l e n i t e t h r e a d s s u r r o u n d e d by c e r e n i t e and c u t i n i t e . The i m p r e g n a t i o n o f Sphagnum c e l l w a l l s w i t h t a n n i n p r e v e n t s g e l i f i c a t i o n e x c e p t under e x t r e m e c o n d i t i o n s . T e l e n i t e w i t h s m a l l l e n s e s o f t e l o c o l l i n i t e w o u l d f o r m a mas-s i v e framework f o r t h e more e x i n i t e - r i c h sedge c o m p o n e n t s . The e v e n t u a l g r o w t h of woody s h r u b s and P i n u s c o n t o r t a w i t h i n t h e d e p o s i t a dd s i g n i f i c a n t amounts o f l i g n i n t o t h e p e a t . A l t h o u g h many l e a f and stem t i s s u e s a r e d e s t r o y e d b e f o r e b e i n g i n c o r p o r a t e d i n t o t h e p e a t f a b r i c , enough s u r -v i v e t o f o r m c u t i n i t e o r s u b e r i n i t e bounded g r a n u l e s of b o t h t e l e n i t e and t e l o c o l l i n i t e . Stem, p i t h , and p e r i d e r m r e -g i o n s , r i c h i n b o t h p r i m a r y and s e c o n d a r y i n c l u s i o n s , add abundant r e s i n d r o p l e t s t h r o u g h o u t t h e s u b e r i n i t e and t e -l e n i t e f r a c t i o n s . S p o r i n i t e i s uncommon, but s m a l l p o c k e t s a r e s c a t t e r e d r a n d o m l y t h r o u g h t h e t e l e n i t e m a t r i x . T h i n l a m i n a e o f e x i n i t e - r i c h t e l e n i t e s o c c u r between m i c r o l a m i n a e of o x y f u s i n i t e , p y r o f u s i n i t e , d e s m o c o l l i n i t e , a n d a b u n d a n t s c l e r o l i n i t e , a nd r e p r e s e n t c h a r c o a l - r i c h e r i c a c e o u s l e n s e s . As s u c h , t h e s e m a c e r a l s g r a d e i n t o more m a s s i v e , e x i n i t e - p o o r h o r i z o n s w i t h i s o l a t e d r e s i n o u s t e l e n i t i c r o o t s and t h i n p o c k e t s o f s u b e r i n i t i c d e s m o c o l l i n i t e . C o n f i n e d t o t h i n l a -minae, b o t h s c l e r o t i n i t e and p y r o f u s i n i t e a r e l e s s common. Randomly i n t e r s p e r s e d t h r o u g h o u t a r e l a r g e s u b e r i n i t e - b o r -d e r e d , r e s i n o u s t e l e n i t e and t e l l o c o l l i n i t e d e r i v e d f r o m t h e wood of P i n u s . C l o s e l y a s s o c i a t e d w i t h t h i c k p y r o f u s i n i t e b a n d s , Nuphar 155 h o l l o w s p r o d u c e a d i s t i n c t m a c e r a l a s s e m b l a g e . The a c c u m u l a -t i o n of r e s i n o u s P i n u s and E r i c a c e a e stem and l e a f t i s s u e i n t h e s e d e p r e s s i o n s f o r m t h i n l e n s e s o f t e l e n i t i c c u t i n i t e , s u b e r i n i t e , and r e s i n i t e . Due t o t h e h i g h l e v e l s o f decompo-s i t i o n , t h e s e d e t r i t a l framework components a r e s u s p e n d e d i n a m a t r i x of i n t e r s p e r s e d l i p t o d e t r i n i t e and d e s m o c o l l i n i t e . The d e p r e s s i o n b o t t o m i s b o r d e r e d by a t h i n band of m a s s i v e t e l i n i t e . The c o m b i n e d i n c r e a s e i n woody t i s s u e f r o m P i n u s , P i c e a , and P o p u l u s stumps and B e t u l a stem h o r i z o n s i n c r e a s e s r e -s i n o u s and s u b e r i n o u s t e l e n i t e masses d r a m a t i c a l l y a l o n g a c t i v e l e v e e m a r g i n s . The i n t e r v e n i n g m a t r i x of banded mac-r i n i t e , o x y f u s i n i t e , i n e r t o d e t r i n i t e , and c u t i n i t e f l o w s a r o u n d t h e s e r i g i d b o d i e s . S c l e r o t i n i t e i s common. P i t t Meadows p e a t s o r i g i n a t e f r o m f r e s h w a t e r m a r s h e s . E a r l i e s t s t a g e s , however, a r e e x t r e m e l y wet, and p r o b a b l y r e p r e s e n t ponded w a t e r . As a r e s u l t , i n i t i a l p l a n t m a t e r i a l i s decomposed t o g y t t j a e , and a c q u i r e t h e c h a r a c t e r i s t i c s o f boghead c o a l s . L i p t o d e t r i n i t e , a l g i n i t e , c u t i n i t e , and d e s -m o c o l l i n i t e form a common a s s e m b l a g e . V a r i a b i l i t y o c c u r s when i n e r t o d e t r i n i t e and m i c r i n i t e r e p l a c e l i p t i n i c m a c e r a l s i n a r e a s w h i c h have u n d e r g o n e p e r i o d s o f d e s i c c a t i o n . V i r -t u a l l y no b a n d i n g i s p r e s e n t i n t h e s e m a c e r a l s , and a m a s s i v e t e x t u r e i s p r o d u c e d . Above t h i s g e n e r a l l y t h i n band, s e d g e - g r a s s p e a t s form 1 56 m a c e r a l s s i m i l a r t o t h o s e i n e q u i v a l e n t p e a t s a t L u l u I s l a n d . However, b e c a u s e o f t h e e a r l y c o l o n i s a t i o n o f Sphagnum a t P i t t Meadows, m a t e r i a l i s b e t t e r p r e s e r v e d , and t e l e n i t e r e -p l a c e s d e s m o c o l l i n i t e t o some e x t e n t . L a t e r a l e q u i v a l e n t s of s e d g e - g r a s s p e a t s c o n t a i n more p y r o f u s i n i t e and o x y f u s i n i t e as w e l l - d e v e l o p e d n a t u r a l l e v e e s a r e a p p r o a c h e d . H i g h l y r e f -l e c t i v e v i t r o d e t r i n i t e and s u b e r i n i t e l a y e r s i n t e r l a m i n a t e w i t h c l a y h o r i z o n s i n t h e l e v e e . A l t h o u g h a b i o f a c i e s com-p a r a b l e t o t h e sedge-wood p e a t s o f L u l u I s l a n d was n o t i d e n -t i f i e d a t P i t t Meadows, i t p r o b a b l y e x i s t s w i t h i n t h e e x t e n -s i v e Sphagnum and e r i c a c e o u s Sphagnum p e a t s p r o d u c e s i m i l a r s e t s o f m a c e r a l s t o t h o s e f o r m e d on L u l u I s l a n d . Due t o g r e a t e r r a i n f a l l a t P i t t Meadows, f i r e h o r i z o n s a r e n o t as t h i c k o r as numerous, and t h u s p y r o f u s i n i t e i s l e s s common. Nuphar p e a t s a r e a b s e n t f o r t h e same r e a s o n . L i p t i n i t i c ma-c e r a l s s u c h as c u t i n i t e and r e s i n i t e and i n e r t i n i t i c m a c e r a l s l i k e o x y f u s i n i t e a r e l e s s common as a r e s u l t . The seam a c -q u i r e s a more u n i f o r m a p p e a r a n c e as w e l l . I n c r e a s e s i n woody m a t e r i a l f r o m P i n u s c o n t o r t a t i s s u e s r a i s e s t h e c o n c e n t r a t i o n o f r e s i n o u s t e l e n i t e and s u b e r i n i t e . 1 5 7 SUMMARY The d e c o m p o s i t i o n a l h i s t o r y of i n d i v i d u a l p l a n t com-p o n e n t s has been i n t e g r a t e d w i t h b o t h t h e p e a t s t r a t i g r a p h y and d e p o s i t i o n a l s e t t i n g s i n t h r e e F r a s e r R i v e r d e l t a p e a t d e p o s i t s . O b s e r v a t i o n s f r o m t h i s s y n t h e s i s have a l l o w e d t h e p r e d i c t i o n o f b o t h m a c e r a l p r e c u r s o r s and s u b s e q u e n t m i c r o -l i t h o t y p e d i s t r i b u t i o n i n r e s u l t i n g c o a l seams. T h i s i n f o r -m a t i o n may a i d i n t h e u n d e r s t a n d i n g of a n c i e n t c o a l s and c o a l - b e a r i n g s t r a t a . T h i n s e d g e - g r a s s p e a t s a t B o u ndary Bay r e p r e s e n t a g r a d -u a l t r a n s i t i o n f r o m m a r i n e c o n d i t i o n s n e a r t h e b a s e t o t h o s e o f f r e s h w a t e r , h i g h e r i n t h e s e c t i o n . The i n i t i a l r a p i d a c -c u m u l a t i o n o f s e d g e - d o m i n a t e d p e a t s b u i l d s t h e s u b s t r a t e above t i d a l i n f l u e n c e . As t h i s o c c u r s , s a l t marsh s p e c i e s a r e r e p l a c e d w i t h t h o s e of f r e s h w a t e r a f f i n i t y . L a c k o f m a r i n e n u t r i e n t s , p e r i o d i c d e s i c c a t i o n , and f i r e s c a u s e t h e s l o w e r a c c u m u l a t i o n o f g r a s s - d o m i n a t e d p e a t s . A f t e r a p e r i o d o f t i m e , t h i s s l o w e r r a t e o f g r o w t h a l l o w s a r i s i n g s e a l e v e l t o g r a d u a l l y . t r a n s g r e s s t h e s e c t i o n . The whole s e c t i o n i s t h e n a l t e r e d by b a c t e r i a whose g r o w t h r a t e s a r e e n h a n c e d by t h e h i g h e r pH o f m a r i n e w a t e r s . P l a n t m a t e r i a l w h i c h i s p r e s e r v e d a p p e a r s y e l l o w t o y e l l o w - o r a n g e i n t h i n s e c t i o n , i n d i c a t i n g t h a t a c c u m u l a t i n g d e b r i s was s e l d o m e x p o s e d t o d e s i c c a t i o n and o x i d i z i n g c o n d i -t i o n s f o r e x t e n d e d p e r i o d s o f t i m e . Under s u c h c i r c u m s t a n -158 c e s , t h e h i g h r a t i o o f c e l l u l o s e t o l i g n i n f orms p r i m a r i l y d e s m o c o l l i n i t e . H i g h c o n c e n t r a t i o n s o f l i p i d s f r o m s e d g e s , d i a t o m s , and o t h e r a l g a e add s i g n i f i c a n t amounts o f t h e e x i n i t e m a c e r a l s c e r e n i t e , c u t i n i t e , and a l g i n i t e . In a t r e n d t o w a r d an emergent e n v i r o n m e n t , o x i d a t i o n and d e s i c c a -t i o n w i l l c a u s e t h e r e p l a c e m e n t o f e x i n i t e and v i t r i n i t e g r o u p m a c e r a l s w i t h i n e r t i n i t e s . O x y f u s i n i t e , p y r o f u s i n i t e , and m i c r i n i t e w i l l become more p r e v a l e n t between t h e d i s c o n -t i n u o u s bands o f d e m o s c o l l i n i t e , c u t i n i t e , and v i t r o d e t r i n -i t e . O n l y n e a r t h e t o p of t h e s e c t i o n w i l l a r e v e r s a l i n t h i s t r e n d o c c u r . Then, l a t e r e r o s i o n and o x i d a t i o n by t r a n s g r e s s i n g m a r i n e w a t e r s w i l l p r e v e n t v i t r i n i t e and e x i n i t e m a c e r a l s from b e c o m i n g d o m i n a n t a g a i n . A l t h o u g h t h i n and of p o o r q u a l i t y , t h i s p e a t w i l l p r o -duce l a t e r a l l y e x t e n s i v e c o a l seams. The base of t h e s e u n i t s w i l l c o n s i s t of t h i c k l e n s e s o f c l a r i t e banded w i t h t h i n d i s -c o n t i n u o u s l a m i n a e o f v i t r i t e . G r a d u a l r e p l a c e m e n t of c l a r i t e w i t h d u r i t e and m i n o r v i t r i n e r t i t e w i l l o c c u r m i d s e c -t i o n , and w i l l c o n t i n u e t o t h e t o p o f t h e seam. The amount of d u r i t e w i l l i n c r e a s e s l i g h t l y a s t h o s e c o a l s formed from s o l e l y f r e s h w a t e r m arshes a r e a p p r o a c h e d l a n d w a r d . C o r r e -s p o n d i n g l y , t h i s m i c r o l i t h o t y p e w i l l d e c r e a s e t o w a r d t h e m a r i n e m a r g i n . L o c a l d r a i n a g e a l s o may c a u s e an i n c r e a s e i n abundance of t h e d u r i t e l e n s e s . Lower s e c t i o n s o f t h e L u l u I s l a n d p e a t d e p o s i t accumu-l a t e d between f l u v i a l d i s t r i b u t a r y c h a n n e l s . The b r a c k i s h 1 5 9 w a t e r e n v i r o n m e n t and a s s o c i a t e d p l a n t community a r e s i m i l a r t o t h o s e o f t h e Boundary Bay p e a t . As a r e s u l t , t h e m a c e r a l f a b r i c s , i n c l u d i n g t h o s e p r o d u c e d by t h e t r e n d t o w a r d f r e s h -w a t e r n i c h e s , w i l l be n e a r l y i d e n t i c a l . However, f l o o d e v e n t s and s u b s e q u e n t c r e v a s s e and f i r e s p l a y s w i l l d i s r u p t t h e s i m p l e i n t e r n a l m a c e r a l d i s t r i b u t i o n n e a r d i s t r i b u t a r y c h a n n e l s a n d p o o r l y d e v e l o p e d n a t u r a l l e v e e s . In t h e s e a r e a s f l o o d i n g by o x y g e n - r i c h , n e u t r a l pH w a t e r s and l a t e r e x t e n d e d p e r i o d s o f d e s i c c a t i o n w i l l c a u s e t h e f o r m a t i o n o f numerous p o c k e t s of i n e r t o d e t r i n i t e , m a c r i n i t e , s c l e r o t i n i t e , and oxy-f u s i n i t e . The i n c r e a s e o f t h e s e i n e r t i n i t e m a c e r a l s between c u t i n i t e - r i c h c l a r i t e bands w i l l e v e n t u a l l y p r o d u c e a f a b r i c o f i n t e r l a m i n a t e d d u r i t e s and v i t r i n e r t i t e s . F r e s h w a t e r s e d g e - g r a s s p e a t s a r e decomposed l e s s t h a n b r a c k i s h w a t e r e q u i v a l e n t s . D e s m o c o l l i n i t e w i l l s t i l l be t h e p r i m a r y m a c e r a l , however. I t w i l l be i n t e r l a m i n a t e d w i t h t e l e n i t e , c u t i n i t e , c e r e n i t e , and l e s s o f t e n w i t h p y r o f u -s i n i t e and s c l e r o t i n i t e . U n l i k e t h e p e a t s a t B o u n d a r y Bay, f l u v i a l i n f l u e n c e p r e v e n t s e x t e n d e d p e r i o d s of d e s i c c a t i o n i n t h i s f r e s h w a t e r h a b i t a t . C l a r i t e , w i t h t h i n bands of i n e r -t i t e and v i t r i t e , w i l l be t h e p r e v a l e n t m i c r o l i t h o t y p e . E v e n t u a l c o l o n i s a t i o n by Sphagnum spp. r e d u c e s b o t h nu-t r i e n t i n f l u x and pH i n t h e e n v i r o n m e n t . P l a n t c o m p o s i t i o n c h a n g e s a s a r e s u l t , and e r i c a c e o u s s h r u b s and P i n u s c o n t o r t a r e p l a c e t h e s e d g e - g r a s s community. Due t o i n c r e a s e d a c i d i t y of t h e e n v i r o n m e n t , t h e s e l i g n i n - r i c h t i s s u e s a r e w e l l p r e -1 60. s e r v e d . S u b e r i n i t e , r e s i n i t e , t e l o c o l l i n i t e , and t e l e n i t e m a c e r a l s w i l l f o r m l a r g e bands of v i t r i t e w i t h p e r v a s i v e l e n s e s o f c l a r i t e and t h i n l a m i n a e of l i p t i t e . Stumps w i l l c u t o b l i q u e l y a c r o s s bands as l a r g e homogeneous v i t r i t e masses. D u r i t e and v i t r i n e r t i t e p o c k e t s w i l l o c c u r above and below p y r o f u s i t e h o r i z o n s . T h e s e bands w i l l i n c r e a s e i n f r e -q uency u p s e c t i o n . O c c a s i o n a l l y t h e y w i l l be a s s o c i a t e d w i t h l a r g e d e p r e s s i o n s w h i c h have been f i l l e d w i t h r e s i n i t e , c u -t i n i t e , s u b e r i n i t e , and t e l i n i t e . T h e s e e x i n i t e - r i c h u n i t s w i l l f o r m c l a r i t e and l i p t i t e m i x t u r e s and h a v e a m a s s i v e t e x t u r e . D u r o c l a r i t e w i l l s u b s t i t u t e f o r v i t r i t e and c l a r i t e where s e d g e - g r a s s p e a t s p r o g r a d e v e r t i c a l l y n e a r c h a n n e l mar-g i n s . On n a t u r a l l e v e e s , d u r i t e and c l a r o d u r i t e bands w i l l i n t e r l a m i n a t e w i t h o v e r b a n k mudstone. L a r g e v i t r i t e stumps w i l l a p p e a r on t h e f l a n k s of t h e b e t t e r - d e v e l o p e d l e v e e s . The e a r l i e s t p e a t s t o a c c u m u l a t e a t P i t t Meadows a r e o r g a n i c - r i c h c h a n n e l - f i l l d e p o s i t s c h a r a c t e r i z e d by f i n i n g upward c y c l e s of f i n e s a n d , s i l t , and c l a y . The s e d i m e n t s c o n t a i n a b u n d a n t r e s i s t a n t b a r k and stem f r a g m e n t s of a l l o c h -t h o n o u s o r i g i n . A u t o c h t h o n o u s sedge c u l m s an d r o o t s a r e a l s o common. Due t o t h e h i g h m i n e r a l c o n t e n t , t h e s e p e a t s w i l l form v i t r i t i c c a r b a r g i l i t e s r i c h i n s u b e r n i t e , c o l l i n i t e , and v i t r o d e t r i n i t e . L a t e r p h a s e s o f t h e s e c h a n n e l - f i l l d e p o s i t s c o n t a i n 16 1 a b u n d a n t g y t t j a of s e d g e - g r a s s o r i g i n . T h i s p e a t t y p e e v e n -t u a l l y c o v e r s t h e whole d e p o s i t , and m i g r a t e s v e r t i c a l l y n e a r a c t i v e c h a n n e l m a r g i n s i n t h e s o u t h . R i c h i n d i a t o m s , o t h e r a l g a e , and c u t i c l e s , t h i s u n i t w i l l f o r m l i p t i t e w i t h t h i n bands of c l a r i t e . L a t e r a l l y , n e a r l e v e e s , i t w i l l i n t e r l a m -i n a t e w i t h c l a r o d u r i t e s , w h i l e v e r t i c a l l y g r a d i n g i n t o a banded c o a l o f c l a r i t e and v i t r i t e . The m a c e r a l t y p e s of b o t h s e d g e - g r a s s and Sphagnum d o m i n a t e d p e a t s a r e s i m i l a r t o t h o s e of t h e L u l u I s l a n d de-p o s i t . However, due t o i n c r e a s e s i n P i n u s and e r i c a c e o u s t i s s u e and an a b s e n c e o f Nuphar h o l l o w s i n t h e P i t t Meadows d e p o s i t , t h e r e l a t i v e a b u n d a n c e s o f m a c e r a l s w i l l be d i f -f e r e n t . V i t r i t e components w i l l i n c r e a s e a t t h e expense of l i p t i t e and s m a l l amounts o f i n e r t i t e . I n t e r n a l m a c e r a l com-p l e x i t y w i l l d e c r e a s e c o n s i d e r a b l y . 162 PLATE 1 M a r i n e o r s a l t w a t e r s e d g e - g r a s s p e a t F i g . 1-1. D e v e l o p m e n t of modern s a l t m a rsh a t B o u n d a r y Bay. T r i g l o c h i n and S a l i c o r n i a a r e t h e i n i t i a l p i o n e e r i n g s p e c i e s o f t h e t i d a l f l a t . F i g . 1-2. S a l i c o r n i a clumps d e v e l o p on d e c a y i n g e e l g r a s s Z o s t e r a mounds. F i g . 1-3. P h o t o m i c r o g r a p h s h o w i n g h i g h l y o x i d i z e d l a y e r s ( o l ) i n more f r e s h w a t e r and emergent s e d g e - g r a s s h o r i z o n s . F i g . 1-4. F a b r i c of s e d g e - g r a s s p e a t s h o w i n g s c a t t e r e d g r a s s stem and d e g r a d e d l e a f f r a g m e n t s ( s t and I f ) i n amor-phous m a t e r i a l . F i g . 1-5. P h o t o m i c r o g r a p h o f v e r t i c a l l y o r i e n t e d g r a s s stem r e m a i n s i n a h i g h l y r o o t e d amorphous m a t e r i a l . 164 PLATE 2 Brackish sedge-grass peat F i g . 2-1. A brackish sedge marsh on Lulu Island composed of a mosaic of Carex, Juncus, Typha and Scirpus• F i g . 2-2. Sc i rpus sp. i s common in modern brackish environ-ments . F i g . 2-3. Photomicrograph of the general f a b r i c of sedge-grass peat, showing poorly developed microbedding of grass stems (st) and amorphous granular debris (gd). F i g . 2-4. Photomicrograph of a well preserved stem of Juncus sp. Such well preserved tissues are rare in t h i s peat type. F i g . 2-5. Sedge-grass peat contains abundant amorphous matrix and c e l l debris. Holes represent l a t e r oxida-tion of r o o t l e t s and stem tissue (o). 165 PLATE 2 166 PLATE 3 Freshwater sedge-grass peat F i g . 3 - 1 . Freshwater marsh at P i t t Polder with Calamogrostis, Carex and Spi rea. F i g . 3-2. Close-up of a cross-section of a sedge rootlet surrounded by highly degraded c e l l fragments and a few fungal hyphae. Note secondary c e l l inclusions (ci) f i l l i n g endoderm c e l l s . F i g . 3-3. Photomicrograph of the amorphous texture encoun-tered in pockets of highly decomposed c e l l debris. A few collapsed grass stems are v i s i b l e (st) near the center of the photograph. F i g . 3-4. Photomicrograph of a cross-section through a Carex sp. stem. Note the breakdown of the central p i t h area and the release of primary c e l l inclusions ( c i ) . F i g . 3-5. Photomicrograph i l l u s t r a t i n g the general fabric of sedge-grass peat. Laminations are formed by the d i s -t i n c t banding of grass stems (st) and leaves with amorphous material (am). 168 PLATE 4 Sedge-Sphagnum p e a t F i g . 4-1. D e p r e s s i o n f i l l e d w i t h z o n e d sedge-Sphagnum b i o f a -c i e s s u r r o u n d e d by hummocks o f P i n u s and e r i c a c e o u s Sphagnum b i o f a c i e s . F i g . 4-2. P h o t o m i c r o g r a p h s h o w i n g t h e p e r v a s i v e r o o t l e t s of R h y n c h o s p o r a and E r i p h o r u m n e a r t h e t r a n s i t i o n from s e d g e - g r a s s p e a t . F i g . 4-3. P h o t o m i c r o g r a p h t h r o u g h a f r a c t u r e d and f o l d e d but undecomposed Ledum l e a f . The l e a f i s s u r r o u n d e d by amorphous sedge d e b r i s . F i g . 4-4. P h o t o m i c r o g r a p h o f t h e w e l l - p r e s e r v e d f a b r i c of sedge-Sphagnum p e a t . A few p o c k e t s o f amorphous d e b r i s i n t e r l a m i n a t e d w i t h Sphagnum l e a v e s ( l v ) and stems and R h y n c h o s p o r a r o o t s ( r t ) . 4-5. C l o s e - u p of a w e l l - p r e s e r v e d R h y n c h o s p o r a r o o t l e t s u r r o u n d e d by Sphagnum l e a v e s . 170 PLATE 5 Sedge-wood peat F i g . 5-1. P i c e a stump i n growth p o s i t i o n surrounded by a sedge-grass m a t r i x . F i g . 5-2. Photomicrograph showing p e r v a s i v e r o o t i n g i n h i g h l y decomposed, s l i g h t l y laminated sedge-grass peat. Darker zone c o n t a i n s more h i g h l y o x i d i z e d ma-t e r i a l . F i g . 5-3. Photomicrograph showing p e r v a s i v e r o o t i n g i n h i g h l y decomposed, s l i g h t l y saminated sedge-grass peat. Darker zone c o n t a i n s more h i g h l y o x i d i z e d ma-t e r i a l . F i g . 5-4. Close-up of an u n i d e n t i f i e d c u t i c l e (cu) and epi dermis (ep) w i t h i n amorphous d e b r i s . F i g . 5-5. Photomicrograph of a c r o s s - s e c t i o n through a w e l l -p r e s e r v e d Oxycoccus stem. 171 PLATE 5 172 PLATE 6 Nuphar peat F i g . 6-1. Nuphar covering the surface of a shallow pond. Fig . 6-2. Allochthonous and p a r t i a l l y f u s i n i t i z e d Pinus needles (Pn) and grass stems (st) in c e l l debris. Fi g . 6-3. Photomicrograph showing a cross-section through a liverwort t h a l l u s ( I t ) . This structure i s l i k e l y the only autochthonous tissue shown. Fig . 6-4. Floating c e l l debris produces an unoriented fabric in t h i s peat type. Fi g . 6-5. Close-up of highly Nuphar a s t r o s c l e r e i d s decomposed tissue, (as) and trichomes with only rema i n i ng. 173 PLATE 6 174 PLATE 7 Sphagnum peat F i g . 7-1. Sphagnum capillaceum and Rhynchospora sp. Are the primary peat-forming plants of t h i s peat type. F i g . 7-2. Sphagnum spores commonly occur as undispersed pockets within the peat f a b r i c . F i g . 7-3. Photomirograph of uncompressed Sphagnum leaf and stem tissue. F i g . 7-4. Fabric of Sphagnum peat showing well preserved and laminated Sphagnum stems and leaves. F i g . 7-5. Photomicrograph shows pockets of highly degraded and oxidized material between Sphagnum tissues. Note Rhynchospora ro o t l e t in the upper portions of the section. 176 PLATE 8 Ericaceous Sphagnum peat Fig . 8-1. Kalmia angusti folium, one of several Ericaceae to be found in Fraser River bog peats. F i g . 8-2. Cross-section of a Vacc inium sp. stem with confor-ming matrix. Only minor decomposition has occurred within these tissues. Fig . 8-3. Photomicrograph of fungal hyphae which are common-ly found between Sphagnum layers. Fig . 8-4. Photomicrograph of p a r t i a l l y degraded Ledum, Kalmia and Oxycoccus leaves in a matrix of Sphagnum leaves. Note the thickenings in the pa l l i s a d e layer c e l l s and the separation of the epidermis. 8-5. Fabric of ericaceous Sphagnum peat showing well-developed microlamination and highly degraded ericad leaf and stem ti s s u e . 177 PLATE 8 178 PLATE 9 Decomposition Fig. 9-1. Cross-section of an undecomposed Pinus contorta needle found in Nuphar peat. Fig. 9-2. Cross-section through a s l i g h t l y decomposed Pinus  contorta needle. A small amount of thinning of tran-sfusion tissue (tt) and a corresponding thickening within the palisade layer (pi) has occurred. Fi g . 9-3. Photomicrograph through a longitudinal cross-sec-tion of a Ledum stem. Note the well preserved p i t h region with primary c e l l inclusions ( c i ) . The re-mainder of the stem, excluding the periderm and epi-dermis, has been converted to a granular g e l . Fi g . 9-4. Complete decomposition of the p i t h region of an ericaceous stem r e s u l t s in the release of primary c e l l inclusions into the amorphous matrix. The p e r i -derm (pd) region i s unaltered. Fig. 9-5. Photomicrograph of an unaltered anther surrounded by highly degraded and oxidized sedge and grass ma-t e r i a l . Note the numerous pollen grains s t i l l enc-losed. 179 PLATE 9 180 PLATE 10 Decomposition F i g . 10-1. Photomicrograph showing thinning of protoxylem (pith) elements and release of primary c e l l i n c l u -sions (ci) of Oxycoccus. F i g . 10-2. Cross-section of an ericaceous stem showing the complete decomposition of xylem and secondary phloem tissue to a fine granular debris (gd). Only the periderm (pm) remains unaltered. F i g . 10-3. Close-up of ericaceous xylem c e l l walls thinning and forming rounded masses of granular gel (gg). F i g . 10-4. Photomicrograph of a cross-section through a Pinus contorta stem under crossed p o l a r i z a t i o n . L i -ghter areas are c e l l u l o s e , while the darker patches within are undergoing decomposition. F i g . 10-5. Photomicrograph i d e n t i c a l to 10-4 except under normal l i g h t . Xylem elements are beginning to a l t e r to pockets of granular g e l . The outer periderm, how-ever, remains unaltered. 181 PLATE 10 1 82 LIST OF REFERENCES A l l e n , E.A.D., 1978. Petrography and stratigraphy of Holocene coastal-marsh deposits along the western shore of Delaware Bay. University of Delaware Department of Geology Ph.D. thesis, 287 p. Bonner, J.F. and Varner, J.E., editors, 1976. Plant Biochemistry. Academic Press, New York, 925 p. Chandra, D. and Taylor, G.H., 1975. Gondwana coals, _in, Coal Petrology. Gebruder Borntraeger, B e r l i n , pp. 139-158. Clague, J . J . , 1975. Late Quaternary sea l e v e l fluctuations of the P a c i f i c Coast of Canada and adjacent areas. Geological Survey of Canada, Paper 75-1, Part C, pp. 17-21 . Cohen, A.D., 1968. The petrology of some peats of southern F l o r i d a , with special references to the o r i g i n of coal. The Pennsylvania State University Ph.D. thesis, 357 p. Cohen, A.D., 1970. An allochthonous peat type from southern F l o r i d a . Geological Society of America B u l l e t i n , v. 81, pp. 2477-2482. Cohen, A.D., 1973. Petrology of some Holocene peat sediments from the Okefenokee swamp-marsh complex of southern 1 8 3 Geological Society of America B u l l e t i n , v. 84, 3878. Cohen, A.D. and Spackman, W., 1972. Methods in peat petrolo-gy and their a p p l i c a t i o n to reconstruction of paleoenvironments. Geological Society of America B u l l e t i n , v. 83, pp. 129-142. Cohen, A.D. and Spackman, W., 1977. Phytogenic organic sedi-ments and sedimentary environments in the Everglades-man-grove complex: Part I I . The o r i g i n , description, and c l a s s i f i c a t i o n of the peats of southern F l o r i d a . Palaeontographica, v. 162B, pp. 71-114. Cohen, A.D. and Spackman, W., 1980. Phytogenic organic sedi-ments and sedimentary environments in the Everglades-man-grove complex of F l o r i d a : Part I I I . The a l t e r a t i o n of plant material in peats and the o r i g i n of coal macerals. Palaeontographica, v. 172B, pp. 125-149. Coleman, J.M. and Smith, W.G., 1964. Studies of Quaternary sea l e v e l . Coastal Studies I n s t i t u t e Technical Report 20, Louisiana State University, pp. 833-340. Envirocon, 1980. Fraser River Estuary habitat development program c r i t e r i a summary report. Prepared for Department of Supply and Services, F i s h e r i e s and Oceans, Canadian W i l d l i f e Service, and Public Works Canada by Envirocon Georgia. pp. 3867-184 Limited, Vancouver, 147 p. Fisk, H.N., 1958. Recent M i s s i s s i p p i River sedimentation and peat accumulation, i_n Van Aelst, Ernest, editor: Congres pour l'Avancement des Etudes de Stratigraphique et du Geologie du Carbonifere. 4th Heerlen, Compte Rendu v. 1, pp. 187-199. F l a i g , W. , 1 968. Biochemical factors in coal formation. i_n Murchison, D.G. and Westoll, T.S., e d i t o r s : Coal and Coal Bearing Strata. Oliver and Boyd, Edinburgh, pp. 233-267. Frazier, D.E. and Osanik, E., 1969. Recent peat deposits -Louisiana coastal p l a i n , i_n Dapples and Hopkins, editors: Environments of Coal Deposition. Geological Society of America Special Paper, no. 114, pp. 63-86. Gray, P., 1958. Handbook of Basic Microtechnique. McGraw-H i l l Book Company Incorporated, New York, 252 p. Hacquebard, P.A., Birmingham, T.F., and Donaldson, J.R., 1967. Petrography of Canadian coals in r e l a t i o n to en-vironment of deposition. Symposium Science and Technology of Coal, Ottawa, 34-97. Hansen, H.P., 1940. Paleoecology of two peat bogs in south-western B r i t i s h Columbia. American Journal of Botany, v. 27, pp. 144-149. 185 Hebda, R.J., 1977. The paleoecology of a raised bog and as-sociated d e l t a i c sediments of the Fraser River Delta, B r i t i s h Columbia. The University of B r i t i s h Columbia, Department of Botany Ph.D. thesis, 202 p. Ke l l e r h a l s , P. and Murray, J.W., 1969. Ti d a l f l a t s at Boundary Bay, Fraser River Delta, B r i t i s h Columbia." B u l l e t i n of Canadian Petroleum Geologists, v. 17, pp. 67-91 . Lyngberg, E., 1979. The palynology and vegetative succession of a peat bog located at northern P i t t Meadows, B r i t i s h Columbia. The University of B r i t i s h Columbia, Department of Botany B.Sc. thesis, 84 p. Mathews, W.G., Fyles, J.G. and Nasmith, H.W., 1970. P o s t g l a c i a l c r u s t a l movements in southwestern B r i t i s h Columbia and adjacent Washington State. Canadian Journal of Earth Science, v. 7, pp. 690-702. Milliman, J.D., 1980. Sedimentation in the Fraser River and i t s estuary. Southwestern B r i t i s h Columbia Estuarine and Coastal Marine Science, v. 10, pp. 609-638. Moore, L.R., 1968. Some sediments clo s e l y associated with coal seams, i_n Murchison and Westall, e d i t o r s : Coal and Coal Bearing Strata. Ohrer and Boyd, Edinburgh, pp. 105-123. . • 1 86 Moore, P.D. and Bellamy, D.J., 1974. Peatlands. Springer-Verlag, New York, 214 p. Northcote, D.H., 1977. Plant Biochemistry. University Park Press, Baltimore, 262 p. Osvald, H., 1933. Vegetation of the P a c i f i c Coast bogs of North America. Acta Phytogeographica Sueica, v. Almqvist and Wiksells, Botryckeri-A.B., Uppsala, 34 p. Rigg, G.B. and Richardson, C.T., 1938. P r o f i l e s of some sphagnum bogs of the P a c i f i c coast of North America. Ecology, v. 19, pp. 408-434. Robinson, T., 1963. The Organic Constituents of Higher Plants: Their Chemistry and Interrelationships.. Burgess Publishing Co., Minneapolis, 306 p. Shepperd, J.E., 1981. Development of a s a l t marsh on the Fraser Delta at Boundary Bay, B.C., Canada. The University of B r i t i s h Columbia, Department of Geological Sciences, M.Sc. thesis, 143 p. Smith, A.H.V., 1962. The paleoecology of carboniferous peats based on the microspores and petrography of bituminous coals. Proceedings Yorkshire Geological Society, v. 33, p. 423-474. Smith, D.G. and Smith, N.D.,, 1980. Sedimentation in anas-tomosed r i v e r systems: examples from a l l u v i a l valleys near Banff, Alberta. Journal of Sedimentary Petrology, v. 50, pp. 157-164. Spackman, W., Riegel, W.L., and Dolsen, C.P., 1969. Geological and b i o l o g i c a l interactions in the swamp-marsh complex of southern F l o r i d a , _in Dapples and Hopkins, edi-t o r s : Environments of Coal Deposition. Geological Society of America Special Paper, no. 114, pp. 1-36. Stach, E., 1975. The microlithotypes of coal and their strength, j_n Coal Petrology. Gebruder Borntraeger, B e r l i n , pp. 108-118. Staub, J.R., and Cohen, A.D., 1978. K a o l i n i t e enrichment beneath coals; a modern analog, Snuggedy Swamp, South Carolina. Journal of Sedimentary Petrology, v. 48, pp. 203-210. Staub, J.R., and Cohen, A.D., 1979. The Snuggedy Swamp of south Carolina: A back-barrier extuarine coal forming environment. Journal of Sedimentary Petrology, v. 49, pp. 133-144. Styan, W.B. and Bustin, R.M., 1981. Sedimentology, petro-graphy and geochemistry of some peat deposits of the Fraser River Delta. Program with abstracts, Joint Annual 1 88 Meeting, Geological Association of Canada; Mineralogical Association of Canada v. 6, p. 54. Teichmuller, M., 1958. Rekonstruktion verschiedener Moortypen des Hauptflozes der niederrheinischen Braunkohle. Fortschr. Geol. Rheinld und Westf., v. 2, pp. 599-612. Teichmuller, M., 1975. Origin of the petrographic c o n s t i -tuents of co a l , ijn Coal Petrology. Gebruder Bortraeger, B e r l i n , pp. 176-238. Teichmuller, M. and Teichmuller, R., 1966. Geological causes of c o a l i f i c a t i o n . Coal Science, Advances in Chemistry S e r i e s , v . 5 5 , pp.133-155. Teichmuller, M. and Teichmuller, R., 1968. Geological as-pects of coal metamorphism. in Murchison, D.G. and Westoll, T.S., edi t o r s : Coal and Coal Bearing Strata. Oliver and Boyd, Edinburgh, pp. 233-267. Ting, F.T.C, and Spackman, W., 1965. Coal lithotypes, their r e l a t i o n s h i p s to the environments of coal forming swamps. Geological Society of America, Programs with Abstracts. 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0052830/manifest

Comment

Related Items