Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
DSpace
UBCV
Sonneveld, Ellen M.
Master of Science - MSc
University of British Columbia
The Lower Mannville Group of south-central Alberta represent part of an extensive Early Cretaceous drainage system incised into Paleozoic carbonates and shales. Sediments were deposited as debris flows, in bars of low sinuosity, sandy braided rivers, and in shallow fresh to brackish water lakes. Late Aptian-Early Albian transgression of the Moosebar-Clearwater Sea lead to formation of a large estuary in the Drumheller area. Petrographic examination of the basal alluvial sands indicates the existence of 3 lithologically distinct sandstones: (1) a basal immature chert arenite; (2) an immature quartz arenite; and (3) a mature to supermature quartz arenite, correlatable with the Ellerslie Formation. The change from cherty sandstone to quartzose sandstone reflects uplift to the east, of the Sweetgrass Arch and Swift Current Platform. Diagenetic modification of the sandstones include compaction and cementation by siderite, quartz, calcite, dolomite, barite, pyrite, and clay, all of which have reduced initial primary porosity. Secondary porosity was subsequently created through dissolution of early siderite cement. Oil emplacement in the Basal Quartz sands appears to follow cementation by siderite and silica. [Note: Oversize leaves 220-228 (maps) and 232-242 (cross sections) available in Rare Books and Special Collections, Irving K. Barber Learning Centre.]
DEPOSITION OF THE CRETACEOUS LOWER MANNVILLE GROUP, DRUMHELLER AREA, ALBERTA by El l e n M. Sonneveld BSc. University of Toronto, 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of Geological Sciences THE FACULTY OF GRADUATE STUDIES We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA March, 1983 © E l l e n Meredith Sonneveld t 19,83 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 available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication 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. Department of 6ez>uDGtc4L- SCIKA/CCTJ The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 (3/81) ti ABSTRACT The Lower Mannville Group of south-central Alberta repre-sent part of an extensive Early Cretaceous drainage system i n -cised into Paleozoic carbonates and shales. Sediments were de-posited as debris flows, in bars of low sinuosity, sandy braided r i v e r s , and in shallow fresh to brackish water lakes. Late Aptian-Early Albian transgression of the Moosebar-Clearwater Sea lead to formation of a large estuary in the Drumheller area. Petrographic examination of the basal a l l u v i a l sands i n d i -cates the existence of 3 l i t h o l o g i c a l l y d i s t i n c t sandstones: (1) a basal immature chert arenite; (2) an immature quartz arenite; and (3) a mature to supermature quartz arenite, correlatable with the E l l e r s l i e Formation. The change from cherty sandstone to quartzose sandstone r e f l e c t s u p l i f t to the east, of the Sweetgrass Arch and Swift Current Platform. Diagenetic modification of the sandstones include compac-tion and cementation by s i d e r i t e , quartz, c a l c i t e , dolomite, ba r i t e , p y r i t e , and clay, a l l of which have reduced i n i t i a l p r i -mary porosity. Secondary porosity was subsequently created through d i s s o l u t i o n of early s i d e r i t e cement. O i l emplacement in the Basal Quartz sands appears to follow cementation by s i d e r i t e and s i l i c a . i i i TABLE OF CONTENTS I. INTRODUCTION 1 1.1. PURPOSE AND LOCATION OF STUDY 1 1.2. REGIONAL GEOLOGIC SETTING 4 1.3. PREVIOUS WORK 12 1.4. METHODS AND DATA 16 I I . STRATIGRAPHIC TERMINOLOGY AND CORRELATION OF UNITS . 23 II I . MISSISSIPPIAN SUBCROPPING UNITS 29 3.1. BANFF FORMATION 29 3.1.1. Lithology 29 3.1.2. Geophysical Log Response 30 3.2 PEKISKO FORMATION 31 3.2.1. Lithology 31 3.2.2. Geophysical Log Response 32 3.3 SHUNDA FORMATION 32 3.3.1. Lithology 32 3.3.2. Geophysical Log Response 33 3.4 DISTRIBUTION OF THE UNITS 33 IV. EARLY CRETACEOUS PALEOTOPOGRAPHY 37 V. LOWER MANNVILLE GROUP SEDIMENTS 40 5.1. DEVILLE FORMATION 40 5.1.1. Lithology 40 5.1.2. Geophysical Log Response 42 5.1.3. Di s t r i b u t i o n And Thickness 44 i v 5.1.4. Deposition Of The De v i l l e Formation 46 5.2. BASAL QUARTZ SANDS 48 5.2.1. Basal Quartz Nomenclature 48 5.2.2. Lithology 49 5.2.3. Petrology Of The Drumheller Sands 56 5.2.4. Geophysical Log Response 82 5.2.5. Dist r i b u t i o n And Thickness 83 5.2.6. Deposition Of The Drumheller Sandstone 88 5.2.7. Sediment Source 97 5.3. ELLERSLIE FORMATION 99 5.3.1. Lithology 99 5.3.2. Geophysical Log Response 100 5.3.3. Di s t r i b u t i o n And Thickness 100 5.3.4. Deposition Of The E l l e r s l i e Formation 100 5.4. CALCAREOUS MEMBER 101 5.4.1. Lithology 101 5.4.3. Geophysical Log Response 107 5.4.2. D i s t r i b u t i o n And Thickness 109 5.4.4. Deposition Of The Calcareous Member 111 VI. UPPER MANNVILLE GROUP SEDIMENTS 118 6.1. GLAUCONITIC SANDSTONE MEMBER 118 6.1.1. Lithology 118 6.1.2. Geophysical Log Response 123 6.1.3. Di s t r i b u t i o n And Thickness 125 6.1.4. Deposition Of The Glauconitic Member 127-VII. DEPOSITIONAL MODEL FOR THE LOWER MANNVILLE 133 7.1. PHYSIOGRAPHY AND TECTONICS 133 7.2. CLIMATIC SETTING 138 7.3. UNCONFORMITIES OF THE LOWER MANNVILLE 139 VIII. REVISION OF STRATIGRAPHIC TERMINOLOGY 144 IX. DIAGENESIS OF THE DRUMHELLER (BASAL QUARTZ) SANDS ..146 9.1. INTRODUCTION 146 9.2. STAGES OF DIAGENESIS 146 9.2.1. Eogenetic Stage 147 9.2.2. Mesogenetic Stage 152 9.3. RED PIGMENT 166 9.4. POROSITY WITHIN THE BASAL QUARTZ SANDS 167 9.5. SUMMARY 170 X. LOWER MANNVILLE OIL AND GAS PRODUCTION 173 10.1. TRAPPING MECHANISMS 173 10.2. TIME OF OIL EMPLACMENT AND MIGRATION 176 10.3. SOURCE BEDS 178 XI. CONCLUSION 179 REFERENCES CITED 181 APPENDIX I - V i t r i n i t e Reflectance 192 APPENDIX II - Palaeontology Summary 203 APPENDIX III - X-Ray D i f f r a c t i o n Analysis 208 APPENDIX IV - Thin Section Locations 211 APPENDIX V - S.E.M. Sample Locations 216 APPENDIX VI - Symbols 217 v i APPENDIX VII - Percent Relief D e f i n i t i o n 218 APPENDIX VIII - Maps 219 APPENDIX IX - Cross Sections 229 v i i LIST OF TABLES I . Lower C r e t a c e o u s C o r r e l a t i o n C h a r t f o r South e r n A l b e r t a and A d j a c e n t Areas 24 I I . D e f i n i t i o n of B a s a l Quartz L i t h o f a c i e s 52 I I I . D e f i n i t i o n of L i t h o f a c i e s i n the C a l c a r e o u s Zone 102 IV. R e v i s e d S t r a t i g r a p h i c Column f o r the Study Area 145 V. C r i t e r e a f o r D i s t i n g u i s h i n g A u t h i g e n i c from D e t r i t a l C l a y s 164 V I . P a r a g e n e t i c Sequence f o r the B a s a l Quartz Sandstones 171 V I I . L o c a t i o n , P o r o s i t y , and R e s e r v e s f o r O i l and Gas F i e l d s i n the Study Area 174 I - I . R e s u l t s from the R e f l e c t a n c e Study 195 I - I I . C o r r e l a t i o n of TTI w i t h V i t r i n i t e R e f l e c t a n c e 201 I - I I I . C o r r e l a t i o n of TTI w i t h Important Stages of O i l G e n e r a t i o n and P r e s e r v a t i o n 201 v i i i LIST OF FIGURES F i g u r e 1. L o c a t i o n of Study Area 2 F i g u r e 2. L o c a t i o n of Lower C r e t a c e o u s O i l and Gas F i e l d s i n the Study Area 4 F i g u r e 3. C r e t a c e o u s R e g i o n a l Paleogeography 7 F i g u r e 4. E a r l y C r e t a c e o u s P a l e o d r a i n a g e 8 F i g u r e 5. E a r l y C r e t a c e o u s P a l e o t e c t o n i c F e a t u r e s 11 F i g u r e 6. P r e v i o u s Work i n Southern A l b e r t a 16 F i g u r e 7. L o c a t i o n of W e l l s and C r o s s - S e c t i o n s 17 F i g u r e 8. L o c a t i o n of Core i n the S t r a t i g r a p h i c I n t e r v a l S t u d i e d 17 F i g u r e 9. P e t r o g r a p h i c C l a s s i f i c a t i o n of Sandstones Adopted i n t h i s Study 20 F i g u r e 10. T r u n c a t i o n of P a l e o z o i c S t r a t a by the P r e -Cr e t a c e o u s U n c o n f o r m i t y 25 F i g u r e 11. G e o p h y s i c a l Log Response of the Subcropping M i s s i s s i p p i a n F o r m a t i o n s 31 F i g u r e 12. Three D i m e n s i o n a l R e p r e s e n t a t i o n of the M i s s i s s i p p i a n S t r u c t u r e 36 F i g u r e 13. G e o p h y s i c a l Log Response of the D e v i l l e F o r m a t i o n 44 F i g u r e 14. D i s t r i b u t i o n of t h e D e v i l l e F o r m a t i o n , C r o s s - S e c t i o n 14 45 ix Figure 15. Drumheller Sandstone Litho l o g i c Logs 54 Figure 16. Drumheller Sandstone Litho l o g i c Logs 55 Figure 17. A. Petrographic C l a s s i f i c a t i o n of the Lower Mannville Sandstones 59 B. Composition of the Framework Grains in the Drumheller Sandstone 59 Figure 18. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 14-10-27-20 W4 73 Figure 19. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 14-15-27-20 W4 74 Figure 20. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 6-22-27-20 W4 75 Figure 21. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 8-22-27-20 W4 76 Figure 22. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 10-23-27-20 W4 77 Figure 23. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 7-02-27-21 W4 78 Figure 24. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 7-17-28-20 W4 79 Figure 25. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 1 1-02-28-21 W4 80 Figure 26. The V e r t i c a l D i s t r i b u t i o n of Petrographic Components in 9-14-28-21 W4 8.1 Figure 27. The V e r t i c a l D i s t r i b u t i o n of Petrographic X Components in 7-23-28-21 W4 82 Figure 28. Three Dimensional Representation of the Drumheller Isopach Map 84 Figure 29. Dist r i b u t i o n of the Drumheller Unit, Cross-Section 3 86 Figure 30. Dis t r i b u t i o n of the Drumheller Unit, Cross-Section 1 87 Figure 31. The Range of Facies Which Could be Produced by Deposition in a Sandy Braided River 93 Figure 32. Drumheller Lithofacies Sequences 1 through 4 94 Figure 33. Drumheller Lithofacies Sequences 5 through 9 95 Figure 34. Drumheller Lithofacies Sequences 9 through 12 96 Figure 35. V e r t i c a l D i s t r i b u t i o n of Lithofacies in the Calcareous Member 106 Figure 36. C h a r a c t e r i s i t i c Log Signatures of the Calcareous Member 108 Figure 37. Dis t r i b u t i o n of the Calcareous Member, Cross-Section 9 111 Figure 38. Formation of Marl Deposits in Lake L i t t l e f i e l d 115 Figure 39. Geophysical and Litholog P r o f i l e s of the x i Carbon Sandstone 124 F i g u r e 40. D i s t r i b u t i o n of the Carbon Sandstone, C r o s s - S e c t i o n 2 126 F i g u r e 41. D e p o s i t i o n a l Model f o r Lower M a n n v i l l e Group Sediments 137 F i g u r e 42. C o r r e l a t i o n Problems 142 F i g u r e 43. P o t e n t i a l M i s c o r r e l a t i o n of U n i t s 143 F i g u r e 1-1. I s o r e f l e c t a n c e C o n t o u r s from M a n n v i l l e C o a l s 1 95 F i g u r e 1-2. L o c a t i o n of Hacquebard's C r o s s - S e c t i o n and Samples 196 F i g u r e 1-3. M a n n v i l l e C o a l i f i c a t i o n Curve 197 F i g u r e 1-4. R e l a t i o n s h i p Between Rank, Temperature and Time of C o a l i f i c a t i o n , a f t e r K a r w e i l 197 F i g u r e 1-5. Contours of Maximum B u r i a l Depth 198 F i g u r e 1-6. G e o l o g i c a l Model f o r the A p p l i c a t i o n of L o p a t i n ' s Method 200 x i i LIST OF PLATES Plate 1. Lithology of the D e v i l l e Formation 42 Plate 2. Petrology of the Drumheller Sandstones 58 Plate 3. Framework Grains in the Drumheller Sandstones 61 Plate 4. Framework Grains in the Drumheller Sandstones 62 Plate 5. Framework Grains in the Drumheller Sandstone 64 Plate 6. Carbonate Cements in the Drumheller Sandstone 66 Plate 7. Habits of Authigenic S i d e r i t e 67 Plate 8. S i l i c a and Barite Cement in the Drumheller Sandstones 69 Plate 9. Authigenic Pyrite 70 Plate 10. Matrix of the Drumheller Sandstone 71 Plate 11. Calcareous Zone Sediments 104 Plate 12. Core Photographs of Upper Mannville Sandstones 120 Plate 13. Additional Core Photographs of Upper Mannville Sandstone 121 Plate 14. S.E.M. Photograph of Si d e r i t e and Pore F i l l i n g K a o l i n i t e 150 x i i i Plate 15. Backscattered Image and Iron Map of a Siderit e Spherulite 152 Plate 16. Compaction and S i l i c a Mobilization 153 Plate 17. S.E.M. Image of Quartz Overgrowth 155 Plate 18. Solution of Si d e r i t e . 158 Plate 19. Late Authigenic Barite Cement 160 Plate 20. S.E.M. Image of Barite Pore F i l l i n g Cement 161 Plate 21. Pyrite as Framboids and Replacing Matrix, S.E.M. Image 1 62 Plate 22. Well C r y s t a l l i z e d Kaolinite Pore F i l l , S.E.M. Image 165 Plate 23. Secondary Porosity in Drumheller Sandstones 168 Plate 24. Time of O i l Emplacement 177 Plate 1-1. Petrographic C h a r a c t e r i s t i c s of the Glauconitic Coal Detritus 194 xiv LIST OF MAPS /" Spec/a.' C° fief e t Map 1. Mississippian Subcroping Formations 220 Map 2. Mississippian Structure Map 221 Map 3. Mississippian Residual 222 Map 4. Mannville Isopach Map 223 Map 5. Lower Mannville Isopach Map 224 Map 6. De v i l l e Isopach Map 225 Map 7. Basal Quartz (Drumheller) Sandstone Isopach Map 226 Map 8. Calcareous Member Isopach Map 227 Map 9. Lithofacies of the Basal Quartz (Drumheller) Sandstone 228 XV LIST OF CROSS SECTIONS- / w S p e c a ' LdetA* Section 1. A-A' 232 Section 2. B-B' 233 Section 3. C-C* 234 Section 4. D-D' 235 Section 5. E-E' 236 Section 6. F-F' 237 Section 7. G-G' 238 Section 8. H-H' 239 Section <\(-. J-J' 240 Section 10. K-K' 241 Section 1.1. L-L' 242 x v i ACKNOWLEDGEMENTS I w i s h t o thank Dr. W. C. Barnes f o r h i s s u p e r v i s i o n , s u p p o r t , and c r i t i c a l r e v i e w s throughout t h i s s t u d y , Dr. R.M. B u s t i n , Dr. J . Murray, and Dr. W. Mathews f o r c r i t i c a l r e a -d i n g of the m a n u s c r i p t , and G. Hodge f o r a i d i n d r a f t i n g . The work on t h i s p r o j e c t was s u p p o r t e d by S h e l l Canada Resources L i m i t e d , who p r o v i d e d a l l w e l l l o g d a t a , a c c e s s t o c o r e , p a l e o n t o l o g i c and p a l y n o l o g i c a n a l y s i s , and t h i n sec-t i o n p r e p a r a t i o n . I wish t o thank a l l those p e o p l e i n v o l v e d , e s p e c i a l l y A. Rupp, who c o o r d i n a t e d and s u p e r v i s e d the work i n C a l g a r y , as w e l l as p r o v i d e d d i r e c t i o n t h r o u g h d i s c u s s i o n . F i n a n c i a l a s s i s t a n c e was p r o v i d e d by the N a t u r a l S c i e n c e s and E n g i n e e r i n g R esearch C o u n c i l of Canada, the American A s s o c i a t i o n of P e t r o l e u m G e o l o g i s t s , and S h e l l Canada Resources L i m i t e d . 1 I . INTRODUCTION 1.1. PURPOSE AND LOCATION OF STUDY Sandstones commonly blanket regional unconformities and thus form a t t r a c t i v e hydrocarbon prospects. Prediction of sandstone geometry and porosity trends is d i r e c t l y related to knowledge of the depositional environment and post deposit-ional modification by erosion and diagenesis. This project was undertaken to acquire an understanding of the l o c a l de-p o s i t i o n a l environment of the Cretaceous Lower Mannville Group at Drumheller Alberta, as related to paleotopography of underlying Paleozoic strata, and to examine subsequent modi-f i c a t i o n of sandstone petrology during diagenesis. The study area is located in the southern Alberta Plains, (Figure 1) centred approximately 90 kilometers (55 miles) northeast of Calgary, and including townships 27 through 30, ranges 20 through 24, west of the fourth meri-dian, a t o t a l area of 1390 square kilometres (537 square miles). Lower Mannville sediments l i e e n t i r e l y within the subsurface, buried at an average depth of 1,475 metres (4,839 fe e t ) . The greatest depths and thicknesses occur in the southwest. At the southern t i p of the area l i e s the Hussar F i e l d which produces both o i l and gas from Lower Mannville sand-stones l y i n g in an erosional low on the sub-Cretaceous sur-face.. The Carbon F i e l d , producing hydrocarbons from basal 2 Figure 1. Location of study area. 3 C r e t a c e o u s sands, i s l o c a t e d c e n t r a l l y w i t h i n the s t u d y a r e a ( F i g u r e 2 ) . The major o b j e c t i v e s of the study are t o : 1 . Map the r e l i e f on the u n c o n f o r m i t y , and the d i s t r i -b u t i o n of o v e r l y i n g u n i t s , e s t a b l i s h i n g a r e g i o n -a l s t r a t i g r a p h i c framework f o r the Lower M a n n v i l l e sediments. 2 . Determine the e f f e c t of the p r e - C r e t a c e o u s u n c o n f o r -m i t y on E a r l y C r e t a c e o u s s e d i m e n t a t i o n p a t t e r n s . 3. Develop d e p o s i t i o n a l models f o r the major Lower M a n n v i l l e c l a s t i c u n i t s . 4. E s t a b l i s h sediment provenance. 5. Examine the d i s t r i b u t i o n and p e t r o l o g y of the B a s a l C r e t a c e o u s sands t o a i d i n e v a l u a t i n g r e s e r v o i r p o t e n t i a l . 6. R e v i s e s t r a t i g r a p h i c t e r m i n o l o g y f o r the a r e a . 1 . 2 . REGIONAL GEOLOGIC SETTING The E a r l y C r e t a c e o u s Epoch r e p r e s e n t s a time of s i g n i f i -c a n t change i n the paleogeography and t e c t o n i c s of the Western Canada Sedimentary B a s i n . The i n t e r p l a y of J u r a s s i c t o E a r l y C r e t a c e o u s C o r d i l l e r a n t e c t o n i c s and L a t e J u r a s s i c e p e i r o g e n i c u p l i f t of the Canadian S h i e l d r e s u l t e d i n complex d e p o s i t i o n of s y n o r o g e n i c non-marine sediments i n a broad d e p o s i t i o n a l t r o u g h which extended from the p r e s e n t Rocky Mountain Trench eastward t o the Manitoba Escarpment (Acham, 4 F i g u r e 2. L o c a t i o n o f Lower C r e t a c e o u s o i l and gas f i e l d s i t h e s t u d y a r e a , ( c o m p i l e d f r o m A l b e r t a S o c i e t y o f P e t r o l e u m G e o l o g i s t s , 1966; 1 9 69). 5 1971 ) . Jurassic sediments in southwestern Saskatchewan and western Alberta are mostly marine, having accumulated during several stages of advance and retreat of the Sundance Sea. Late Jurassic u p l i f t of the Precambrian Shield, and an eusta-t i c drop in sea level (McLean, 1982) forced retreat of Jurassic seas southward and led to the erosional stripping of Early Mesozoic and Paleozoic rocks extending from southern Saskatchewan to central Montana (Christopher, 1975). The marine-continental t r a n s i t i o n i s marked by deposition of two sand units in southwestern Saskatchewan, a marine Jurassic shoreline sand, the Rosery sand, and the Jura-Cretaceous Success sand, deposited in f l u v i a l systems transporting large volumes of eroded sediment, and at times i n c i s i n g deeply into underlying strata. According to Christopher (1975) l a t e s t Jurassic and e a r l i e s t Cretaceous rivers in the Sweetgrass Arch area flowed southward towards retreating Jurassic seas. To the west, Hamblin and Walker (1979) show drainage to the north during deposition of the Late Jurassic-Early Cretaceous Kootenay Formation. A major change in the drainage pattern of Alberta during the Early Cretaceous resulted from u p l i f t in the southwest and southeast. Williams (1963), Williams and Stelck (1975) and McLean (1981), describe the p r i n c i p a l drainage of the North American continent as being towards the northwestern P a c i f i c , with access to the ocean r e s t r i c t e d by the develop-ment of highlands in the west and southwest associated with 6 the Columbian Orogen. Rivers drained to the northern P a c i f i c through a broad gulf, analogous to the present Gulf of St. Lawrence, bounded by the Omineca and Nelson highlands (Figure 3(1)). Paleontological evidence indicates elimination of t h i s trough at the close of the Hauterivian as u p l i f t in the Omineca, Nelson, and Idaho bath o l i t h i c mountains formed a continuous highland barring the flow of waters to the P a c i f i c (Williams and Stelck, 1975). Rivers shifted their courses to flow north into the A r c t i c Ocean. The Early Cretaceous rive r system was extensive, as i l l u s t r a t e d by McGookey et a l . (1972), who depicted early Aptian drainage from Arizona, New Mexico, and northern Texas flowing into Canada, and draining into the northern ocean. Williams (1963) recognized 3 major northwest-southeast trending Early Cretaceous r i v e r systems in Alberta: the S p i r i t , Edmonton, and St. Paul channels (Figure 4). Areas of non-deposition extending from southern Montana, northwest across the Alberta Plains to northeastern B r i t i s h Columbia represent ridges of r e s i s t i v e Devonian and Mississippian s t r a t a . During late Aptian-early Albian time (Lower Mannville-Upper Mannville t r a n s i t i o n ) , transgression of a northern sea led to inundation of the former drainage basin possibly to a lat i t u d e south of Calgary (Figures 3(2) and 4). The trans-gression may r e f l e c t an eustatic r i s e in sea l e v e l as e v i -denced by coeval advance of seas on the A t l a n t i c , P a c i f i c and Mexican margins (Williams and Stelck, 1975). A complex assem-blage of t i d a l , d e l t a i c , f l u v i a l and marine sediments was Cretaceous Regional Paleogeography Figure 3. Cretaceous regional paleogeography (after Williams and Stelck, 1975). 8 F i g u r e 4. A. E a r l y C r e t a c e o u s sediments of A l b e r t a were d e p o s i t e d by a s e r i e s of n o r t h w e s t - s o u t h e a s t t r e n d i n g r i v e r systems. B. The Moosebar-Clearwater Sea t r a n g r e s s e d southward d u r i n g the l a t e A p t i a n ( m o d i f i e d from McLean, 1981). 9 deposited throughout southern Alberta. In the late Albian, a mixing of A r c t i c calcareous fora-minifera with exotic elements from the Gulf of Mexico i s re-corded in the geological record, indicating a connection be-tween the southward transgressing Clearwater Sea, and the southern Sundance Sea (Williams and Stelck, 1975). This large inland Cretaceous seaway i s represented by the marine sedi-ments of the Colorado Group (Figure 3(3)). Numerous tectonic and geographic elements influenced deposition of the Mannville and stratigraphic equivalents during the Early Cretaceous: 1. Highlands in the west associated with the Cordilleran Columbian Orogen (Eisbacher et a l . , 1974) . 2. The Canadian Shield, an emergent, t e c t o n i c a l l y stable highland which was u p l i f t e d in the Late Jurassic (Christopher, 1975). 3. The Early Cretaceous northern seaway, which trans-gressed southward in the Late Aptian and again in the Late Albian (McLean, 1981). 4. Lowlands of southern Saskatchewan, northern Montana, and most of Alberta (Glaister, 1959). 5. The Sweetgrass Arch, a positive tectonic feature extending from northern Montana northeastward into southern Alberta, which formed a highland during the e a r l i e s t Jurassic, was subdued during the l a t e s t Jurassic, and u p l i f t e d in the Early 10 Cretaceous, (Christopher, 1975). 6. An intracratonic basin in southern Saskatchewan, possibly part of the W i l l i s t o n Basin (Gla i s t e r , 1959) . 7. The Swift Current Platform which was u p l i f t e d during the e a r l i e s t Cretaceous resulting in erosion of Jurassic and e a r l i e s t Cretaceous sediments, (Christopher, 1975). 8. The Fox Creek Escarpment, which ran p a r a l l e l to the modern Rocky Mountains and formed the eastern edge of a major Early Cretaceous drainage system, the S p i r i t River system (McLean, 1977). 9. The marginal basin, located at the current position of the B r i t i s h Columbia-Alberta border, in which accumulated molasse sediments from the Jurassic-Cretaceous Columbian Orogen and the Late Cretaceous-Tertiary Laramide Orogen (Gla i s t e r , 1959; McLean, 1977). Figure 5 i l l u s t r a t e s the location of these tec-tonic features with respect to the study area. In the Drumheller area, Cretaceous beds l i e with s l i g h t angu-lar unconformity on Mississippian carbonates and shales. Mesozoic and Paleozoic beds dip s l i g h t l y south of west at 3.8 m km'1 (20 feet per mile) and 5.6 m km"1 (30 feet per mile) respectively (Acham, 1971). 1 r Figure 5. Early Cretaceous paleotectonic features, (si m p l i f i e d from Beck, Christopher, and Kent, 1980; McLean, 1977). 1 2 1.3. PREVIOUS WORK Defi n i t i o n of the Mannville Group, as i t is recognized today, i s a r e f l e c t i o n of work by numerous geologists study-ing the subsurface stratigraphy of Alberta. Specialized stu-dies of hydrocarbon f i e l d s and reservoir sands within the Mannville have been published by members of the petroleum industry (Erickson and Crewson, 1959; Berry, 1974). Larger regional stratigraphic and petrographic reports have been compiled as part of graduate research (Glaister, 1959; Williams, 1963). Only the most s i g n i f i c a n t reports r e l a t i n g to the Mannville of southern Alberta are discussed here, in chronological order. Comprehensive summaries of published material r e l a t i n g to Lower Cretaceous strata of Alberta have been presented by G l a i s t e r (1959) and Hayes (1982). The name Mannville was introduced by Nauss (1945) to designate a l i t h o l o g i c a l l y d i s t i n c t group of predominantly non-marine Lower Cretaceous strata in the Vermilion area of Alberta. The unit, s t r a t i g r a p h i c a l l y bounded by the eroded Paleozoic surface and by marine Colorado Group shales, con-s i s t s of 137 metres (449 feet) of non-marine quartz sand-stones, grey shales, salt and pepper sandstones, coals, and a thin marine shale at the type l o c a l i t y (Northwest Mannville No. 1 Well, Lsd. 1, Sec. 18, Twp. 50, Rge. 8, W 4 Mer.). The unit was given formation status by Nauss and subdivided into six members based upon sandstone composition and paleontolo-gic data. In ascending order these are the Dina, Cummings, Islay, T r o v e l l , Borradile, and O'Sullivan members, l o c a l to 1 3 the Vermilion Area. Wickenden (1948) d i f f e r e n t i a t e d the Mannville of the Lloydminster area into three major units, a Basal Quartz Sand Series, the Glauconitic Sand Series, and an upper Coaly Series. Layer (1949), defined a similar three-fold subdivi-sion of the Mannville at Imperial's Leduc No. 1 Well (Lsd. 5, Sec 22, Twp 50, W4 Mer.). Loranger (1951;1954) reported on an abundance of ostra-cods and charophytes, commonly accompanied by pelecypods and gastropods, in the basal brackish unit of the Glauconitic Sand Series. Loranger noted the co r r e l a t i o n of thi s unit at Imperial's Leduc No. 1 Well with Blairmore strata in the foo-t h i l l s , and emphasized i t s use as a regional marker to define the base of the Glauconitic Sand Series. The Mannville Formation was raised to group status by Badgley (1952), and the formational names McMurray, Clearwater and Grand Rapids, in order of decreasing age, as-signed to the three previously informally designated units. Workman (1958) discussed the stratigraphic complexities of the Glauconitic Sandstone Member of the Clearwater Formation. A comprehensive study of Lower Cretaceous strata in southern Alberta, integrating subsurface and outcrop data with published material, was prepared by Gl a i s t e r (1959). He divided the Mannville Group into an upper and lower unit, based upon a marked change in sandstone composition. The boundary was placed at the base of the Glauconitic Sandstone, distinguishing quartz r i c h sands, from sands containing abun-1 4 dant unstable rock fragments r e f l e c t i n g d i f f e r e n t sediment provenances. Packages of sand defined in various areas of Alberta were correlated and depositional models proposed. Gla i s t e r (1959) j u s t i f i e d extending usage of the Mannville terminology south to the international boundary by sandstone correlat ion. D e t r i t a l orthoclase and authigenic glauconite from the Lower Mannville Group in central Alberta were dated by the potassium argon method by Williams et a l . , (1962). They sug-gested a Precambrian source area for the sediments of the McMurray Formation and a Mesozoic source rock for the younger Grand Rapids sandstones. Williams (1963) named the D e v i l l e Formation as the basal unit of the Mannville. His detailed stratigraphic-petrograph-ic study of the Mannville Group in central Alberta augmented the results of Mellon and Wall (1961) and G l a i s t e r (1959). Price (1963) attempted to define the regional extent of the Mannville Group. The subsurface stratigraphy of the central plains was studied by Rudkin (1965) and Mellon (1967), both following the twofold subdivision of the Mannville proposed by G l a i s t e r (1959). Acham (1971) proposed a model for deposi-tion of the Mannville Group in the Hussar area and presented chemical analyses of shales. McLean (1977) presented evidence for the existence of a major north-south trending channel system with northward flow during the Early Cretaceous in Western Canada, based upon stratigraphic relationships within the Cadomin Formation. A detailed report on Jura-Cretaceous 1 5 sands in the Medicine River area, southwestern Alberta, was made by Hopkins (1981), who reported the existence of several d i s t i n c t sands separated by unconformities within the unit generally termed the Basal Quartz Sand or E l l e r s l i e Formation. A regional stratigraphic study of Jurassic and Lower Cretaceous sandstones of southern Alberta was completed by Hayes (1982). James (1982) is currently examining regional stratigraphy and cor r e l a t i o n of Lower Mannville units in Townships 10 through 20, Range 27 W4 to the f i f t h meridian, incorporating data from f o o t h i l l s outcrop sections. The Mannville Group of Saskatchewan has been studied extensively by Maycock (1967) Christopher (1975; 1977), and Beck, Christopher and Kent (1980). Christopher (1975) pre-sented a detailed stratigraphic and l i t h o l o g i c report, i n -cluding depositional models, of the Mannville in Saskatchewan. In Figure 6, the location of previous and cur-rent research in Alberta, south of latitude 53° (range 46), is i l l u s t r a t e d . 1.4. METHODS AND DATA Geophysical well logs from 512 wells were examined and formation tops picked from r e l i a b l e data (Figure 7). Fourteen regional cross sections were constructed employing the spon-taneous potential, gamma ray, sonic or density, and r e s i s t i -v i t y logs. From wireline logs, the following maps were cons-tructed: 1. D i s t r i b u t i o n of subcropping Mississippian formations 16 1945-Nauss Vermi111 on Area 1948-Wlckenden L 1 o y d m l n i s t e r A r ea 195 1 - L o r a n g e r 1-5-22-50W4 1952-Badg ley Edmonton-L 1 o y d m i n i s t e r A rea 1956-Mel Ion and Wal1 S o u t h w e s t e r n A l b e r t a 1958- Workman S o u t h e r n A l b e r t a S o u t h o f Twp. 40 1959- E r i c k s o n and Crewson Wayne O i l F i e l d 1959-G1ai s t e r Sou the rn ' A l b e r t a , Sou th o f Twp. 60 . 1962- Wi11iams e t . a l . L 1 o y d m i n i s t e r a r e a 1963- Pr i ce C e n t r a l A l b e r t a 1965-Rudk i n S o u t h e r n A l b e r t a 1967-Me l l on S o u t h e r n A l b e r t a 1971-Acham Hussa r F i e l d 1974-Ber ry Grand Fo rk s F i e l d 7-10-11-13 W4 1977-McLean Cadomin Fm.- F o o t h i l l s 1981- H o p k i n s M e d i c i n e R i v e r A rea Twp .39 , R.3 W5 1981 A G A T - C o n s u l t a n t s Twp. 1-20. R.6-22 W4 1982- Hayes S o u t h e r n A l b e r t a , And n o r t h e r n Montana . 1983- James • Twp .10-20 , R.27W4 to W5 1983-Sonneve ld Twp .20-27 , R.27-30 W4 F i g u r e 6. P r e v i o u s a n d c u r r e n t L o w e r M a n n v i l l e G r o u p s t u d i e s i n A l b e r t a s o u t h o f r a n g e 46 ( 5 3 ° N o r t h ) . Figure 7. Location of wells d r i l l e d previous to September 1981 which penetrate Mississippian strata in the study area, and cross-sections constructed in t h i s study. Cl r - — t a - t - 1 mi l i um I • 31 \ • 30 j • * s • 1* ' • • ..' 29 ' H N| N(lJ • — 28 I6H4 25H4 24H4 k 21H4 > ! ian4 1 • • zl t8H4, 1 taKIIIIIIlp • J i — ; r WELLS WITH COHLi IN INI 135-i38*^ '——hi Figure 8. Location of core in the statigraphic i n t e r v a l studied. 18 2. Mississippian structure 3. Mississippian residual 4. Mannville Group isopach 5. Lower Mannville Group isopach 6. De v i l l e Formation isopach 7. Basal Quartz Sand isopach 8. Calareous Member isopach 9. Lithofacies of the Basal Quartz unit. These maps can be found in Appendix VIII. Combined with stratigraphic sections, the paleodrainage pattern was recons-tructed from the Mississippian structure, subcrop, and r e s i -dual maps, and the Mannville, Lower Mannville and Basal Quartz isopach maps. Seventy-three cored intervals were examined (a t o t a l of 1663 m (5456 feet)) and sampled for lithology, paleontology, and palynology (Figure 8). Paleontological samples were pro-cessed at Shell Canada Resources Labs in Calgary, and exam-ined by Tony Audretsch and Kay Leskiw. Thin sections were prepared from selected samples, impregnated with blue epoxy for porosity i d e n t i f i c a t i o n , stained with sodium c o l b a l t i n i -t r i t e for ease in recognition of potassium feldspars, and with A l i z a r i n Red S for c a l c i t e . Selected samples within the t o t a l study area were powdered and dispersed in water to pre-pare oriented mounts by the sedimentation method for X-ray d i f f r a c t i o n analysis of clays. Petrology of the Basal Quartz Sandstones was examined in greater d e t a i l in selected wells from townships 27 and 28, 19 ranges 20 and 21. The v e r t i c a l d i s t r i b u t i o n of components was tabulated from thin section and X-ray d i f f r a c t i o n data. Using thin section examination as the basis for selection, 11 sam-ples were examined and photographed with a scanning electron microscope. For each sample, a polished thin section, and a fractured chip were coated with carbon and examined to iden-t i f y r elations between the various components and to examine clays. Mineral i d e n t i f i c a t i o n was aided by an energy disper-sive X-ray spectrometer attached to the SEM. Samples selected for SEM analysis were also examined by cathodoluminescence' microscopy. V i t r i n i t e reflectance was measured on 12 samples of coaly debris embedded in the sandstones and shales of the Upper Mannville Glauconitic Sandstone. The a n a l y t i c a l methods and results are discussed in Appendix I. The sandstone c l a s s i f i c a t i o n of Folk (1968) has been modified for description of the Lower Mannville sands (Figure 9). A c l a s s i f i c a t i o n was desired which would d i f f e r e n t i a t e sands based on provenance. This c l a s s i f i c a t i o n , based on framework components, recognizes d i f f e r e n t source areas for quartz and chert, and ignores effects of later diagenesis. To use this c l a s s i f i c a t i o n , a l l essential components are r e c a l -culated to 100%, omitting clay matrix, chemically p r e c i p i -tated cements and other accessory componants. The result is plotted on t r i a n g l e 1 of Figure 9. If chert and rock frag-ments are abundant, they are recalculated to 100% and plotted on triangle 2. If the rock i s a sedarenite, sedimentary rock 20 Quartz, Metaquartzite •QUARTZ ARENITE SUBARKOSE SUBLITH ARENITE Fe ldspar .G r an i t e and Gneiss Fragments Sedimentary Rock Fragments SEDARENITE Chert and Rock Fragments (Other than granite and SWeiss) Sandstone, Shale 3 " SANDSTONE. fcSHALE ARENITES Volcanic Rock Metamorphic Carbonate Fragments Rock Fragments u u n a x e Chert Figure 9. Petrographic c l a s s i f i c a t i o n of sandstones adopted in this study (modified after Folk, 1968). 21 fragments are recalculated to 100% and plotted on triangle 3. The adjectives immature, submature, and mature are usually added to indicate textural maturity of the sediment. Immature is defined as a poorly sorted sandstone with angular frame-work grains in greater than 5% terrigenous clay matrix (Folk, 1968). In t h i s study the term argillaceous i s used to.specify those sandstones with greater than 15% clay matrix. In attempts to determine the environment of sand deposi-tion, a datum on a stratigraphic marker above, but close to, the upper surface of the sandstone bed results in best recon-struction. Datums chosen below the units may r e f l e c t deforma-tion of the marker due to compaction occurring during growth of the overlying sand body, or r e f l e c t changes associated with unconformities (Conybeare, 1976). The datum for recons-truction of paleotopography and construction of stratigraphic sections was chosen as the top of the Mannville Group. It is readily distinguished on logs and marks transgression of the Late Cretaceous Colorado sea over a broad coastal pl a i n in the study area. Although coal seams exist throughout the area in the Upper Mannville, none could be traced unambiguously. D i f f e r e n t i a l compaction of sands and shales creates d i f -f i c u l t y in interpretation of o r i g i n a l sandstone geometry. In an environment where both were deposited, reconstruction of paleotopography by contructing isopach maps of an i n t e r v a l may lead to apparent highs where a shale f i l l e d depression existed. If a thin widespread marker bed runs through the diff e r e n t units, an estimate of the compaction ef f e c t could 22 be d e t e r m i n e d . U n f o r t u n a t e l y no such markers e x i s t i n the Lower M a n n v i l l e of the D r u m h e l l e r a r e a . 23 I I . STRATIGRAPHIC TERMINOLOGY AND CORRELATION OF UNITS The r e g i o n a l s t r a t i g r a p h y and c o r r e l a t i o n of Lower C r e t a c e o u s s t r a t a f o r A l b e r t a and southwestern Saskatchewan i s p r e s e n t e d i n T a b l e I . The s t r a t i g r a p h i c nomenclature f o r Lower C r e t a c e o u s b a s a l u n i t s i s complex because of the l i t h o -l o g i c v a r i a t i o n and l i m i t e d l a t e r a l e x t e n t of many of the sand b o d i e s . I t i s i m p o r t a n t t o r e c o g n i z e the e x i s t e n c e of sand packages, or l i t h o s o m e s , a s v o p p o s e d t o l a y e r s , when c o r -r e l a t i n g u n i t s i n the Lower C r e t a c e o u s of A l b e r t a . L o c a l de-p o s i t i o n and e r o s i o n must be c o n s i d e r e d as contemporaneous p r o c e s s e s . In an environment where u n i t s were d e p o s i t e d by d o m i n a n t l y f l u v i a l p r o c e s s e s , the o r i e n t a t i o n of the u n i t s c o n t r o l l e d by t e c t o n i c movements and e r o s i o n a l l a n d s c a p e s , t h e r e w i l l be numerous unconformable c o n t a c t s and d i s c o n -t i n u o u s sand b o d i e s . R e c o g n i t i o n of t h i s s t y l e of s t r a t i -graphy has l e d t o the i n t r o d u c t i o n of a m u l t i p l i c i t y of l o c a l names, and the development of an i n t r i c a t e system of nomenc-l a t u r e . The base of the i n t e r v a l s t u d i e d i s marked by a major r e g i o n a l u n c o n f o r m i t y , w i t h J u r a - C r e t a c e o u s s t r a t a r e s t i n g on M i s s i s s i p p i a n s t r a t a . The u n c o n f o r m i t y p r o g r e s s i v e l y t r u n -c a t e s o l d e r r o c k s from west t o e a s t ( F i g u r e 10). The upper boundary of the i n t e r v a l i s p l a c e d a t the t o p of the G l a u c o n i t i c Sandstone Member. In the study a r e a , the Lower M a n n v i l l e Group, c o n s i s t s of the D e v i l l e F o r m a t i o n , the B a s a l Quartz Sands, the E l l e r s l i e F o r m a t i o n , and the C a l c a r e o u s Member. McLean and Wall Mclean and Wall McLean and Wall E.R.C.B. (1979) McLean and Wall Christopher (197S) Source ( 1 9 8 1 ) (1981) (1981) (1081) E.R.C.B. (1979) • •• • I-I.. W E S T Foothil ls Plains E A S T JURASSIC and CRETACEOUS F i g u r e 1 0 . A s t r u c t u r a l c r o s s - s e c t i o n i l l u s t r a t i n g t h e p r o g r e s s i v e t r u n c a t i o n o f o l d e r s t r a t a f r o m w e s t t o e a s t b y t h e p r e - C r e t a c e o u s u n c o n f o r m i t y ( m o d i f i e d f r o m R.M. P r o c t e r a n d G. M a C a u l e y , 1 9 6 8 ) . Ni Oi 26 The D e v i l l e Formation i s similar to the Dev i l l e of Saskatchewan and south-central.Alberta, where i t is often referred to as the D e t r i t a l or Residual Zone. The upper and lower contacts may appear either gradational or disconfor-mable. Hopkins (1981), studying the Lower Cretaceous strata in the Medicine River area, noted sands of Jurassic age over-lying the D e v i l l e , thus placing the D e v i l l e in the Middle to Late Jurassic. Christopher (1975) attaches a Jura-Cretaceous age to this unit in Saskatchewan. The type l o c a l i t y for the D e v i l l e Formation i s between 1084 and 1099 metres (3555.5 and 3605 feet) in the Imperial D e v i l l e No. 1 Well, Lsd. 9, Sec. 36, Twp. 51, Rge. 20, W 4 Mer. The Basal Quartz sands are time equivalent to the Success and Dina sands of southwestern Saskatchewan, de-scribed by Christopher (1975), and the Cadomin Formation in the Alberta F o o t h i l l s . They resemble the J2 Jurassic sands recently recognized by Hopkins (1981), and are Late Jurassic to Neocomian in age. The upper and lower contacts may be d i s -conformable or conformable. The E l l e r s l i e Formation i s l i t h o l o g i c a l l y d i s t i n c t from the former units and considered to be of middle Early Cretaceous age (Aptian). The E l l e r s l i e Formation correlates with the Sunburst, Cutbank, and Taber sands in southern Alberta, and with the McCloud Member in southwestern Saskatchewan. Over most of central Alberta the upper and lower contacts are gradational. The type l o c a l i t y for the E l l e r s l i e i s at Imperial Whitemud No. 3 Well, Lsd. 3, Sec. 27 15, Twp. 51, Rge. 25, west of the Fourth Meridian. The term Basal Quartz Sands has often been used to desi-gnate the interval of c l a s t i c units lying between the pre-Cretaceous unconformity and the base of the Calcareous Member, including the E l l e r s l i e , and Devi l l e units. This term is non-specific and has been used to describe any Jura-Cretaceous sands which rest on the unconformity, being ac-cepted in areas where cor r e l a t i o n of units i s ambiguous. Hopefully, with further research and d r i l l i n g the need for this term w i l l disappear and individual sand packages w i l l be recogn i zed. The Calcareous Member, of Aptian age, i s often referred to as the Ostracod Zone, (Loranger, 1951). In the study area, th i s fine-grained unit, overlies sands of the E l l e r s l i e or Basal Quartz units or i s found resting d i r e c t l y on Deville shale or Mississippian limestone. The lower contact i s sharp-ly defined and possibly disconformable. The upper boundary can be either conformable, or l o c a l l y unconformable where channelling beneath the Glauconitic Sandstone has occurred. The Calcareous Member correlates with the Ostracod Zone of southern Alberta, and with the upper units of the McCloud Formation in southwestern Saskatchewan. The term Calcareous Member i s preferred to Ostracod Zone as i t defines a l i t h o -stratigraphic unit which can be i d e n t i f i e d beyond the boun-daries of the zone f o s s i l Metacypris persulcata (Loranger, 1951). The Glauconitic Sandstone, the lowermost member of the 28 Upper M a n n v i l l e i s a l i t h o l o g i c a l l y complex u n i t of A p t i a n age. The member c o r r e l a t e s w i t h the B l u e s k y sands i n n o r t h -western A l b e r t a , the G l a u c o n i t i c Sandstone a t the base of the C l e a r w a t e r F o r m a t i o n i n n o r t h e a s t e r n and s o u t h - c e n t r a l A l b e r t a , the Moulton Member of s o u t h e a s t e r n A l b e r t a , the upper sandstone of the Cummings Member i n the L l o y d m i n i s t e r r e g i o n , and the Dimmrock Creek Member of southwestern Saskatchewan. No s u b s u r f a c e type l o c a l i t y has been a s s i g n e d t o the G l a u c o n i t i c Sandstone. The upper c o n t a c t of the member i s g r a d a t i o n a l w i t h the o v e r l y i n g sands and c o a l s of the Upper M a n n v i l l e Group. The G l a u c o n i t i c Sandstone i s o v e r l a i n by unnamed con-t i n e n t a l d e p o s i t s of the Upper M a n n v i l l e Group, which a r e e q u i v a l e n t t o the Grand R a p i d s F o r m a t i o n of s o u t h - c e n t r a l A l b e r t a . 29 I I I . MISSISSIPPIAN SUBCROPPING UNITS Within the study area, the Banff, Pekisko and Shunda Formations subcrop beneath the pre-Cretaceous unconformity. For a detailed description of lithology and subdivision of Mississippian rocks of southern Alberta, the reader is re-ferred to the symposium "Jurassic and Carboniferous of Western Canada" (Moore, 1958). Only a brief summary of i n f o r -mation applicable to the study area and objectives i s pre-sented here. 3.1. BANFF FORMATION 3.1.1. Lithology The Banff Formation, Kinderhookian in age, consists of l i g h t grey to brown, argillaceous, p e l l e t a l and skeletal limestone, interbedded with grey to grey green calcareous shales. Beds of sandstone and marlstone are also present. Crinoids, brachiopods, b i o c l a s t i c debris, o o l i t e s , and p e l -l e t s have been noted in the limestone. Where overlain d i r e c t -ly by Cretaceous strata, the uppermost beds are commonly red. The formation grades l a t e r a l l y into argillaceous dolostone, chert, and s i l t s t o n e to the west of the study area, r e f l e c -ting the t r a n s i t i o n from shelf to basin sediments (Boreski, 1978). The Banff Formation has a higher content of c l a s t i c material than the Pekisko and Shunda Formations. 30 3.1.2. G e o p h y s i c a l Log Response As i l l u s t r a t e d i n F i g u r e 11, the r e l a t i v e i m p e r m e a b i l i t y and s h a l i n e s s of the Banff i s r e f l e c t e d i n a p o s i t i v e spon-taneous p o t e n t i a l . H i g h r e s i s t i v i t i e s , low s o n i c t r a v e l t i m e s , and h i g h n e u t r o n r a d i a t i o n i n t e n s i t i e s a r e c h a r a c t e r -i s t i c of the Banff F o r m a t i o n . The gamma i s v a r i a b l e , but g e n e r a l l y shows low r a d i o a c t i v i t y . 3.2 PEKISKO FORMATION 3.2.1. L i t h o l o g y In the study a r e a the P e k i s k o F o r m a t i o n , Osagean i n age, c o n s i s t s of cream p e l l e t o i d a l g r a i n s t o n e and o o l i t i c g r a i n s -t o n e , w i t h o c c a s i o n a l i n t e r b e d s of l i g h t green s h a l e . C r i n o i d s , b r y o z a , b r a c h i p o d s and c o r a l s were noted i n the l i m e s t o n e . In the Twinning F i e l d , s l i g h t l y n orthwest of the s t u d y a r e a , where i t forms the r e s e r v o i r r o c k , B o r e s k i (1978) d i v i d e d the P e k i s k o i n t o two main f a c i e s : 1) A s h o a l f a c i e s , c o n s i s t i n g of o o l i t i c s k e l e t a l g r a i n s t o n e and echinoderm-bryozoan g r a i n s t o n e , both l a c k i n g m i c r i t i c m a t r i x , and 2) A bank f a c i e s , c o n s i s t i n g of e c h i n o d e r m - b r y o z o a n - p e l l e t o i d a l g r a i n s t o n e , e c h i n o d e r m - b r y o z o a n - p e l l e t o i d a l p a c k s t o n e , s k e l e -t a l wackestone and mudstone. Where o v e r l a i n d i r e c t l y by C r e t a c e o u s beds, the P e k i s k o F o r m a t i o n i s commonly c h a l k y i n the uppermost beds. 11.-2.2-29-20 W4 6-30-30-24W4 S.P. Conductivity Gamma r Ray Bulk Density i ) I DEVILLE ( j } 1 SHUNDA I f j > F i g u r e 1 1 . G e o p h y s i c a l l o g r e s p o n s e o f t h e s u b c r o p p i n g M i s s i s s i p p i a n f o r m a t i o n s . 32 3.2.2. Geophysical Log Response The Pekisko is ea s i l y recognized and consistent in i t s log signature. The spontaneous potential i s negative, r e f l e c -ting the lack of matrix, and the induction logs record high r e s i s t i v i t i e s , often reading off scale. High sonic v e l o c i t y and low gamma ray ra d i o a c t i v i t y characterize the Pekisko for-mation. Within the study area, the Pekisko is overlain either by Lower Cretaceous e l a s t i c s or by Shunda carbonaceous shales and limestones. The contact is generally sharp and readily determined on wireline logs. Locally, where the Shunda i s very limy or the overlying d e t r i t a l deposits contain blocks of limestone, some uncertainty in d e f i n i t i o n of the Pekisko top may a r i s e . 3.3 SHUNDA FORMATION 3.3.1. Lithology The Shunda Formation, Osagean in age, i s the youngest of the three subcropping units. It consists of interbedded ar-gillaceous limestone, s i l t y argillaceous dolostone, s i l t -stone, sandstone, shale, and solution breccias in the study area (Boreski, 1978). Anhydrite and red beds are l o c a l l y pre-sent. Towards the f o o t h i l l s , Penner (1959) noted a facies change at the top of the formation to brown, lithographic limestone. 33 3.3.2. Geophysical Log Response The high c l a s t i c content of the Shunda i s r e f l e c t e d in the response of the wireline logs. A positive spontaneous potential, high r e s i s t i v i t i e s , low gamma r a d i o a c t i v i t y , and low sonic travel times characterize the Shunda. Within the study area, the Shunda, where present, is overlain unconform-ably by lower Cretaceous e l a s t i c s . The heterogeneity of the d e t r i t a l unit above the Shunda may lead to ambiguity in p i c -king the Mississippian top in areas where the l a t t e r i s t h i n . The log signatures of the Banff and Shunda Formations could p o t e n t i a l l y be confused were i t not for their stratigraphic separation by and relationship to the Pekisko limestones. 3.4 DISTRIBUTION OF THE UNITS The subcrop pattern of the Mississippian units i s a fun-ction of both the o r i g i n a l depositional d i s t r i b u t i o n and the extent of the erosion which created the unconformity, the l a t t e r exerting more control. Penner (1959) showed the Mississippian subcrop through southern Alberta to consist in general of closely p a r a l l e l northwest-southeasterly trending units, post-Paleozoic erosion progressively truncating older units towards the northeast. Erosion of the Mississippian units led to development of northwesterly oriented ridges and valleys which were la t e r i n f i l l e d by Cretaceous e l a s t i c s . The subcrop pattern within the study area i s presented in Map 1 . The Banff Formation i s confined to the northeastern 34 sector of the map, and the Shunda largely to the west. The bulk of the area i s underlain by the Pekisko Formation. Extensive pre-Cretaceous erosion can be detected on the subcrop map. In the northwest sector of the map, deepest ero-sion i s marked by the subcropping Pekisko Formation. Si m i l a r l y , deep valleys have been carved through the Pekisko limestone, resulting in the older Banff Formation subcropping in the middle of the study area. The structure on the Mississippian surface, presented in Map 2, r e f l e c t s the general west-southwest dip of the unconformity, and the topo-graphy carved during erosive events. The surface i s patterned by north and northeast trending ridges and va l l e y s . Depth to the Mississippian surface ranges from 530 m in the east to 770 m in the west. The Mississippian structure map appears to r e f l e c t , in part, the variable resistance of the subcropping units to post-Paleozoic erosion; however i n s u f f i c i e n t core was exam-ined through the contact to evaluate t h i s properly. A major structural low through the study area ( Twp. 30, R. 22) i s elongate p a r a l l e l to the s t r i k e of subcropping formations. It is located at the eastern margin of the Pekisko Formation subcrop, and most l i k e l y indicates a bed with low weathering resistance. Where Pekisko limestones subcrop, greatest v a r i a -tions in r e l i e f on the unconformity are indicted by the closely spaced contours in contrast to areas underlain by the Shunda or Banff Formation. Pre-Cretaceous paleotopography i s examined in the next chapter. 35 A t h r e e d i m e n s i o n a l g r a p h i c r e p r e s e n t a t i o n of the M i s s i s s i p p i a n s t r u c t u r e i s p r e s e n t e d i n F i g u r e 1 2 , viewed u p d i p towards the n o r t h e a s t . 36 Figure 12. Three dimensional representation of the Mississippian structure, viewed updip. Northwest trending ridges dominate the Mississippian structural surface. Percent r e l i e f is a scaling factor which determines the z value of the three dimensional image with respect to the x and y dimensions of the area portrayed. A detailed d e f i n i t i o n i s presented in Appendix 7. 37 IV. EARLY CRETACEOUS PALEOTOPOGRAPHY Major trends of the post-Paleozoic paleodrainage pattern within the study area can be defined through interpretation of the Mississippian subcrop and structure maps, and an iso-pach map of the Lower Mannville. The image of paleotopography thus obtained represents an average over a period of time. It would be erroneous to consider a l l r i v e r s defined by the maps to have been active simultaneously. The northwest trending contacts between Mississippian formations on the subcrop map are marked by east-west and northeast-southwest trending deflections, suggesting an east-west trend for many pre-Cretaceous valleys and ridges. East-west trending subcrops of the Pekisko Formation, east of the Pekisko-Banff contact, can be interpreted as r e s i s t i v e paleo-highs. The most prominent feature on the map i s a north-south trending subcrop of the Banff Formation west of the Pekisko-Banf f contact (Twp 30, R. 22). This can be interpreted as a major paleovalley. Possible continuation of the valley south-ward i s suggested by smaller subcrops to the southeast. The northwest-southeast trend of contours on the Mississippian structure map r e f l e c t s the regional dip of the surface. After removal of the dip, residuals show a complex pattern with 80 metres r e l i e f . The greatest residual can be interpreted as a north south trending plateau centred in tow-nship 30, range 22, Lsd. 9. It i s flanked to the east by a steep-sided valley which correlates with the low previously 38 described. A broad low of lesser r e l i e f i s centred at town-ship 29, range 23, Lsd. 2. A composite isopach of the Lower Mannville units (Map 5) shows a dissected surface dominated by broad upland areas and wide va l l e y s . There are 15 to 75 metres of f i l l . Thin and thick areas of f i l l correlate with residual highs and lows respectively, c o r r e l a t i n g well with those defined by the Mississippian residual map. The isopach cannot accurately r e f l e c t the pre-Cretaceous surface paleotopography for no allowance has been made for d i f f e r e n t i a l compaction of sand and shale; however i t does provide some information. The most prominent paleohigh, indicated by the thinnest cover of Lower Mannville sediment, i s centred in township. 30, range 22, co r r e l a t i n g with the northwest-southeast trending plateau defined by the residual map. A steep sided, northwest-south-east trending valley, extending through the .length of the study area and cor r e l a t i n g with previously noted lows on the Mississippian subcrop and structure maps, is interpreted from the thickest accumulation of Lower Mannville sediments. To the east of t h i s low, the trend of f i l l i s southwest-north-east. To the west, a more mature surface is suggested by the wider spacing of contours. Combined, the three maps suggest a low r e l i e f surface existed during the Early Cretaceous, patterned by both north-south and east-west trending features. In the northeast sec-tion of the study area, a north-south trending valley i s sug-gested. To the east of t h i s low, smaller broad, northeast-39 southwest t r e n d i n g v a l l e y s and r i d g e s are i n d i c a t e d , p o s s i b l y s i t e s of l o c a l t r i b u t a r i e s d r a i n i n g h i g h l a n d s f u r t h e r e a s t . R e s i s t i v e Devonian h i g h s s l i g h t l y e a s t of the D r u m h e l l e r a r e a have been i l l u s t r a t e d i n the r e g i o n a l p a l e o g e o g r a p h i c r e c o n s -t r u c t i o n by McLean (1981) ( F i g u r e 4 ) . 40 V. LOWER MANNVILLE GROUP SEDIMENTS 5.1. DEVILLE FORMATION 5.1.1. Lithology Several l i t h o f a c i e s have been recognized in the D e v i l l e Formation: waxy green and red shales, occasionally slickens-l i d e d , u n l i t h i f i e d green-grey clays, poorly sorted chert sandstones, green-grey s i l t y shales, green-grey and maroon si l t s t o n e s , and matrix supported chert breccias. Fragments of skeletal calcarenites occur occasionally. The chert breccias, volumetrically the dominant faci e s , are composed of l i g h t grey, often t r i p o l i t i c , angular chert c l a s t s in a poorly sorted, green-grey or red-brown matrix of sand and s i l t . The breccias are matrix supported. Clasts ran-ging in diameter from 0.2 mm to 8 cm are found in variable abundance throughout the unit. Rounded c l a s t s are uncommon. The breccias appear massive, exhibit slump structures, or occasionally show upward f i n i n g of chert c l a s t s . The a r g i l l a -ceous facies, dominantly c l a y - r i c h shales, i s massive or ex-h i b i t s high-angle bedding, greater than 20 degrees. Authigenic pyrite i s commonly associated with waxy green shales. Within the De v i l l e unit individual l i t h o f a c i e s are im-possible to correlate between wells, either in cores or from wireline logs. Rapid l a t e r a l facies variations and v e r t i c a l 41 h e t e r o g e n e i t y t y p i f y the u n i t . P e t r o g r a p h i c a l l y , the D e v i l l e sandstones a r e v e r y p o o r l y s o r t e d , immature c h e r t a r e n i t e s , w i t h framework g r a i n s , i n o r d e r of d e c r e a s i n g abundance, of c h e r t , m o n o c r y s t a l l i n e q u a r t z , p o l y c r y s t a l l i n e q u a r t z , c h a l c e d o n y , and a r g i l l a c e o u s rock f r a g m e n t s . G r a i n s range from a n g u l a r t o subrounded and from v e r y f i n e t o v e r y c o a r s e . C h e r t dominates the c o a r s e r f r a c t i o n . Remnant c a r b o n a t e t e x t u r e s and c a r b o n a t e pseu-domorphs a r e v i s i b l e i n many of the c h e r t g r a i n s . P l a t e 1 i l l u s t r a t e s some of t h e s e t e x t u r e s . C l a y - d o m i n a t e d m a t r i x may compose as much as 40 p e r c e n t of any sample. A u t h i g e n i c s i -d e r i t e , as pore f i l l i n g cement or i n the form of s p h a e r o s i -d e r i t e , i s common. No a u t h i g e n i c q u a r t z was r e c o g n i z e d . P o r o s i t y of the D e v i l l e sands i s secondary and u s u a l l y low. O i l s t a i n i n g was o b s e r v e d . O r i e n t e d c l a y mounts a n a l y z e d by x-ray d i f f r a c t i o n r e v e a l the presence of degraded i l l i t e and d i s o r d e r d kao-l i n i t e i n v a r y i n g p r o p o r t i o n s . In most samples k a o l i n i t e was the dominant c l a y . 5.1.2. G e o p h y s i c a l Log Response D e t e c t i o n of the upper and lower b o u n d a r i e s of the D e v i l l e F o r m a t i o n on g e o p h y s i c a l w e l l l o g s can be d i f f i c u l t because of the extreme l i t h o l o g i c h e t e r o g e n e i t y of the u n i t . D e f i n i t i o n of the D e v i l l e on l o g s i s based on c o n t r a s t s i n l o g c h a r a c t e r between a heterogeneous u n i t and homogenous sandstone above or l i m e s t o n e below. Where the u n i t i s com-42 P l a t e 1. L i t h o l o g y of the D e v i l l e F o r m a t i o n . A. D e v i l l e c h e r t b r e c c i a , (15-36-29-20 W4, 1354.0 m e t r e s ) . C o i n i s 24 mm i n d i a m e t e r . B. C h a l c e d o n i c g r a i n i n the D e v i l l e sandstone, composed of r a d i a t i n g m i c r o q u a r t z f i b e r s , ( c r o s s e d p o l a r i z e d l i g h t , x257, 14-15-27-20 W4, 1400.5 metres) C. D e t r i t a l c h e r t g r a i n from the D e v i l l e b r e c c i a , d e r i v e d from a s i l i c i f i e d c a r b o n a t e ( p l a n e l i g h t , x64, 14-10-27-20 W4, 1397.0 m e t r e s ) . D. R e l i c t c a r b o n a t e t e x t u r e s i n a c h e r t nodule ( c r o s s e d p o l a r i z e d l i g h t , x257, 7-23-28-21 W4, 1472.1 m e t r e s ) . 43 posed of shales and overlain by Early Cretaceous fine to medium grained sandstones, i t i s e a s i l y recognized by a posi-tive spontaneous pot e n t i a l , low r e s i s t i v i t y , and high radioa-c t i v i t y when compared with sandstones. Where the D e v i l l e i s sandy and chert r i c h , i t is d i f f i c u l t to d i s t i n g u i s h from the Basal Quartz sandstones. In those wells where Devi l l e shale i s overlain by shales of the Calcareous Member, i t is v i r -t u a l l y impossible to ident i f y the upper contact with c e r t a i n -ty (Figure 13). 5.1.3. Dis t r i b u t i o n and Thickness Within the study area, the D e v i l l e ranges in thickness from 0 to 24 m (0 to 79 f e e t ) . D i s t r i b u t i o n of the unit i s presented in an isopach map (Map 6). Upon comparison of t h i s pattern with the paleogeography suggested by the Lower Mannville isopach map (Map 5) and Mississippian residual map (Map 3), the areal extent and thickness of the D e v i l l e ap-pears largely controlled by the topography of the sub-Cretaceous unconformity and the location of overlying sand-stone deposits. The thickest accumulations are found on slopes defined by the Mannville isopachs, and in valley bot-toms (see cross-sections, Appendix IX). Some of the material transported to the base of the valleys may have been removed. Thin accumulations of the D e v i l l e in valley bottoms correlate with thick deposits of the Basal Quartz sands, as i l l u s t r a t e d in Figure 14, a simpified version of cross-section 8 (Appendix IX). The thinnest deposits are commonly found in - 44 F i g u r e 13. G e o p h y s i c a l l o g response of the D e v i l l e F o r m a t i o n . D e v i l l e s h a l e s i n A, and sandstones i n B, are o v e r l a i n by B a s a l Q u a r t z s a n d s t o n e s . km. F i g u r e 14. D i s t r i b u t i o n o f t h e D e v i l l e F o r m a t i o n , c r o s s -s e c t i o n 14. N o t e t h e a b s e n c e o f D e v i l l e s e d i m e n t s i n p a l e o v a l l e y s where B a s a l Q u a r t z s a n d s t o n e s a r e t h i c k e s t . 46 h i g h l a n d a r e a s . Tongues of D e v i l l e b r e c c i a and s h a l e , i n t e r -bedded w i t h B a s a l Quartz s a n d s t o n e s , were noted i n s e v e r a l c a s e s . From c o r e o b s e r v a t i o n s , a r e l a t i o n s h i p between the d i s -t r i b u t i o n of D e v i l l e l i t h o f a c i e s and u n d e r l y i n g rock type can be i n f e r r e d . B r e c c i a s a r e common where P e k i s k o l i m e s t o n e s s u b c r o p beneath the u n c o n f o r m i t y , sandstones and s h a l e s dominate where a r g i l l a c e o u s l i m e s t o n e s of the Shunda and Ban f f F o r m a t i o n s subcrop. 5.1.4. D e p o s i t i o n of the D e v i l l e F o r m a t i o n The l i t h o l o g y , d i s t r i b u t i o n , and h e t e r o g e n i e t y of the D e v i l l e F o r m a t i o n can be ac c o u n t e d f o r by l o c a l d e r i v a t i o n and t r a n s p o r t of sediment formed by w e a t h e r i n g of a c a r b o n a t e bedrock. A l a c k of e x t e n s i v e t r a n s p o r t i s suggested by the c o r r e l a t i o n of D e v i l l e l i t h o f a c i e s w i t h s u b c r o p p i n g M i s s i s s i p p i a n l i t h o l o g i e s . Red and green s h a l e s and c l a y s t o n e s of the D e v i l l e F o r m a t i o n a r e i n t e r p r e t e d as p a l e o s o l s composed of i n s o l u b l e r e s i d u e s d e r i v e d from s o l u t i o n of P a l e o z o i c c a r b o n a t e s and s h a l e s . I n d i c a t o r s of e x t e n s i v e t r a n s p o r t a r e l a c k i n g . The r e a c t i o n between d i s s o l v e d CO i n r a i n and s o i l w a t e r s w i t h c a r b o n a t e m i n e r a l s over an e x t e n s i v e p e r i o d of t i m e , r e s u l t s i n f o r m a t i o n of an i n s o l u b l e r e s i d u e s of q u a r t z , c l a y s , and i r o n o x i d e s . Where l e a c h i n g i s moderate t o i n t e n s e , s o l u t i o n c a v i t i e s may f i l l w i t h t e r r a r o s a s o i l s as i n the M e d i t e r r a n e a n area today. The p r o c e s s of l e a c h i n g of l i m e -47 stone and accumulation of clays was examined experimentally by Carrol and Starkey (1959) who found that with average r a i n f a l l of 1 metre per annum, the rate of land denundation would be 6.8 mm per thousand years, r e s u l t i n g in development of an argillaceous weathering crust. The predominance of de-t r i t a l i l l i t e and kaolinite in the D e v i l l e shales suggests long and deep weathering under p a r t i a l l y humid conditions. The D e v i l l e breccias are very poorly sorted deposits, with large chert c l a s t s f l o a t i n g in a finer sand, s i l t , and mud matrix. Thickest accumulation of sediment in valleys and on lower paleoslopes suggests transport may be gravity i n -duced. The presence of convoluted, slumped, and massive beds may indicate rapid transport of the sediment as a f l u i d or p l a s t i c mass. The D e v i l l e breccias were most l i k e l y deposited as debris flows during floods on Early Cretaceous a l l u v i a l fans. Chert nodules embedded in the s k e l e t a l mudstones and wackestones of the Pekisko Formation as described by Boreski (1978) could be released by solution and mechanical wea-thering. With intensive solution, these nodules would concen-trate in a rubble zone at the surface. A whitish outer band observed in many of the c l a s t s probably formed by solution of carbonate inclusions during weathering and exposure. Weathering of Mississippian carbonates and shales would result in development of rounded landforms and surface karst features. Debris flows on l o c a l a l l u v i a l fans would form as minor t r i b u t a r i e s draining l o c a l highs entered the valleys of major t r i b u t a r i e s . The interbedding of D e v i l l e breccias with 48 Basal Quartz sandstones indicates deposition, in part, conte-mporaneously with the sands. 5.2. BASAL QUARTZ SANDS The term Basal Quartz i s used to denote sandstones un-conformably resting on Paleozoic carbonates and shales. The Basal Quartz Sands have been studied as potential hydrocarbon reservoirs, interest being sparked by the discovery of the Carbon and Wayne Fi e l d s , located within the study area. Previous studies interpret these sediments as products of d e l t a i c , a l l u v i a l , or marine processes (Gla i s t e r , 1959; Williams, 1963; Hunt, 1950). 5.2.1. Basal Quartz Nomenclature The Basal Quartz sandstone within the study area i s d i s -t i n c t from the Sunburst, Cutbank, and Taber sandstones to the south, and from the E l l e r s l i e and McMurray sandstones to the north, presently correlated with the Basal Quartz unit. No formal name has previously been given to these sands. It i s proposed that the unit be named the Drumheller Sandstone. The sandstone has been extensively cored in townships 27 and 28, ranges 20 and 21, near the town of Drumheller. A representi-tiv e section has been cored in High f i e l d et a l . Wayne 14-25-27-20 W4. The sandstone i s 24.9 m thick at t h i s location, conformably overlying chert breccias and claystones of the D e v i l l e Formation, and overlain by sandstones of the 49 E l l e r s l i e Formation. A detailed description of the sandstone follows. 5.2.2. Lithology Within the study area, the basal Cretaceous sandstones can be divided into three members: a basal argillaceous (im-mature) chert arenite, an immature to submature quartz arenite .to sublitharenite, and a mature quartz arenite inter-bedded with dark grey shales. The la s t i s equivalent to the E l l e r s l i e sands of south-central Alberta (Hunt, 1950; Gl a i s t e r , 1959), and w i l l be discussed in a subsequent sec-tion under that t i t l e . The argillaceous chert arenite and sublitharenite to submature quartz arenite are not readily distinguished from each other on geophysical logs; thus they have conventionally been grouped together. The contact be-tween sands is observed as either disconformable or composi-t i o n a l l y gradational. The two l i t h o l o g i e s , t e x t u r a l l y similar and exhibiting the same sedimentary structures, are described as one unit. As with the De v i l l e Formation, several facies can be recognized within the Drumheller unit, each characterized by a combination of textural and str u c t u r a l features. Nine facies were i d e n t i f i e d from cores in thi s study. In order of decreasing abundance, these are: 1. Sandstone which i s white to buff, fine to medium grained, poorly sorted and lacking d i s t i n c t bed-ding or lamination. 50 2. Sandstone which is buff or white, fine to medium grained, moderately sorted, and crossbedded in sets greater than 5 cm thick. Large scale cross-bedding seen in cores appears tabular, dipping 15° to 30° across a 9 cm core. 3. Sandstone which i s medium grained, poorly sorted, and horizontally bedded or laminated, lacking bioturbation or grading. 4. Quartz s i l t s t o n e s which are uniform buff to grey, poorly sorted, with angular grains of quartz, and occasionally exhibit root structures. Quartz grains f l o a t in a matrix of clay and organics with small muscovite grains aligned p a r a l l e l to bedding as a common accessory. Phytoclasts are common and highlight root structures. 5. Fine grained, moderately sorted sandstones, red brown to mottled red brown and grey, and lacking in well defined bedding structures. 6. Clay r i c h shales which are l i g h t green to grey, in beds 2 to 10 cm thick, exhibiting thin sets of rip p l e crossbeds in a few cases. These shales are ir r e g u l a r l y dispersed throughout the sandy frac-tion of the unit and are bedded at high angles, suggesting that they may be large mud c l a s t s or clay drapes on bar slopes. Fine grains of musco-v i t e aligned p a r a l l e l to bedding are common. 7. Red brown to mottled red brown and grey, structure-51 less, quartzose s i l t s t o n e s . 8. Sandstone which i s fine to medium grained and exhi-b i t s slump structures, convoluted bedding, and small scale gravity f a u l t s , suggesting deforma-tion contemporaneous or shortly after deposition. 9. Sandstone which i s white to buff, medium to coarse grained, and contains randomly oriented l i g h t green to grey mud c l a s t s . This unit exhibits a sharp erosive contact with underlying s t r a t a . 10. Coal seams which are thin and composed dominantly of v i t r i n i t e . These rare beds were encountered high in the stratigraphic section and are probab-ly allochthonous logs. To simplify future references to these facies, and for construction of l i t h o l o g i c columns, abbreviations for each unit have been defined, modified after the system proposed by M i a l l (1978), for c l a s s i f i c a t i o n of f l u v i a l f a c i e s . A summary of the units and abbreviations is presented in Table I I . The v e r t i c a l sequence of l i t h o f a c i e s in the Drumheller Sandstone unit i s variable. The 8 sections in Figures 15 and 16 t y p i f y the unit. The symbols used in the l i t h o l o g i c logs are defined in Appendix VI. Homogeneous sands are occasional-ly found interbedded with chert breccias of the D e v i l l e Formation, as in 11—18—27—19W4, or in upward f i n i n g sequences with coarse lag at the base and abundant coaly d e t r i t u s above, as in 4-31 - 18-21W4. In paleovalleys the Drumheller sands commonly have blocky geophysical log p r o f i l e s , as in 6-T a b l e II - SUMMARY OF BASAL QUARTZ FACIES FACIES DESCRIPTION SVMBOL COMMENTS Mass 1ve Sandstone S t r u c t u r e l e s s f i n e to medium g r a i n e d sand-s t o n e Sm A s s o c i a t e d w i t h h i g h energy environments. Cross-Bedded Sandstones C r o s s b e d s e t s g r e a t e r than 5 cm. t h i c k , e i t h e r p i a n a r or t r o u g h c r o s s beds ( d i p a n g l e s 15-35 d e g r e e s ) Sx (Sp) ( S t ) A s s o c i a t e d w i t h moderate to h i g h c u r r e n t ve1oc i t i es. Hor i z o n t a l Bedded Sandstone Hor i zonta1 b e d d i n g o r 1 am 1nat i o n v i s i b l e . Sand f i ne to medium g r a i ned. Sh Where a s s o c i a t e d w i t h a lower energy e n v i r -ornment, h o r i z o n t a l b e dding r e f l e c t s s e t 1 1 i n g from s u s p e n s i o n of g r a i n s . Where t h i c k e r beds a r e noted, d e p o s i t i o n i s u s u a l l y from the up-per f l o w regime d u r i n g which bedforms a r e o b l i t e r a t e d from the sediment s u r f a c e . Maroon Sandstone M a s s i v e or Bedded Sox The maroon c o l o u r i n d i c a t e s o x i d a t i o n and r e f l e c t s exposure above the water t a b l e . U n i f o r m Grey S i 1 t s t o n e Mass i ve, may be r o o t e d , o f t e n hos t i ng coa11y debr i s. F ( F r i f r o o t e d ) F i n e grey s i l t s a r e a s s o c i a t e d w i t h q u i e t environments. c o n t i n u e d Table I I . D e f i n i t i o n of Basal Quartz L i t h o f a c i e s . FACIES DESCRIPTION SYMBOL COMMENTS Red-Brown m o t t l e d s i 11-s t o n e Mass 1ve mot t l e d Fox O x i d i z e d s i l t s a r e commonly a s s o c i a t e d w i t h i n t e r f l u v i a l a r e a s . C 1 a y s t o n e s L i g h t green to grey , i n beds 2 to 10 cm. t h i c k bedded at 30 degrees to the hor i z o n t a l , may be u n c o n s o l i d a t e d . F c l C l a y r i c h beds a s s o c i a t e d w i t h s e t t l i n g of suspended m a t e r i a l at the waning phase of a f1ood event. Deformed San d s t o n e s G r a v i t y m i c r o -f a u I t s . con-v o l u t e d beds, and slumps, i n f i ne to medium sand-stone . Sd Some d e f o r m a t i o n may r e f l e c t i n c r e a s e d t u r b u l a n c e d u r i n g the t r a n s i t i o n between lower and h i g h e r flow regime, or d u r i n g storm d e p o s i t i o n . Scour Based Sandstone T h i s u n i t may be ho s t s r i p up c l a s t s of c h e r t or f i n e s h a l e . Ss The e r o s i v e n a t u r e of t h i s u n i t i s i n d i c a t e d by the r i p up c l a s t s and c o a r s e g r a i n s i z e Such a d e p o s i t i s u s u a l l y a s s o c i a t e d w i t h channel bottoms and t i d a l i n l e t s . Coal Usua11y found as d i s s e m i n a t e d d e b r i s i n san d s t o n e s c A s s o c i a t e d w i t h f r e s h water d e p o s i t s , a l l o c h t o n o u s . Table I I . Continued. 11-18-27-19W4 4-31-28-21W4 6-25-27-20W4 10-8-29-22W4 Figure 15. Drumheller Sandstone l i t h o l o g i c logs. 10-22-27-20W4 7-33-27-20W4 10-14-28-21W4 6-32-29-23W4 y F i g u r e 16. D r u m h e l l e r S a n d s t o n e l i t h o l o g i c " l o g s . 56 25-27-20W4, and are massive or exhibit high angle bedding. Well 10-8-29-22W4 i l l u s t r a t e s a case in which upward coar-sening sands capped by a thin coal are overlain by massive and slumped s i l t y sandstones containing abundant phytoclasts and red zones. 10-22-16-20W4 (Figure 16), i l l u s t r a t e s a mul-t i s t o r y sand body. The Drumheller Sandstone unit can be very thin, as in 6-32-29-23W4, t o t a l l y absent in a well, or be composed of maroon and grey quartzose s i l t s t o n e s (7-33-27-20W4). 5.2.3. Petrology of the Drumheller Sands Thin sections (133) and SEM samples (11) were examined to determine the petrographic nature of the Drumheller sand-stones and to evaluate reservoir q u a l i t y . Where possible, a plot of depth verses modal percentage of components was cons-tructed to monitor the changes in sediment character with depth. • - The two l i t h o l o g i c a l l y d i f f e r e n t sands are t e x t u r a l l y s i m i l a r . Both are moderately to poorly sorted, fine to medium grained, muddy sandstones, with interbedded shales. The sands range from those with a high percentage of clay matrix to moderately well sorted, fine to medium grained sands with up to 20% porosity and l i t t l e matrix. Textural maturity varies with grain s i z e . The finer sandstones tend to have a greater percentage of matrix clays, with angular to subangular quartz grains f l o a t i n g in the matrix. Sorting i s poor and porosity very low. Medium to fine grained sandstones exhibit a 57 v a r i a b l e degree of s o r t i n g , w i t h s u b a n g u l a r t o w e l l rounded framework g r a i n s e x h i b i t i n g p o i n t , l o n g , concavo-convex, and s u t u r e d c o n t a c t s as w e l l as f l o a t i n g i n the m a t r i x c l a y s . The sands may be b i m o d a l , the f i n e r g r a i n s showing g r e a t e r angu-l a r i t y . S o r t i n g i s poor t o good, and p o r o s i t y low t o moderate ( P l a t e 2 ) . U s i n g the c l a s s i f i c a t i o n m o d i f i e d from F o l k (1968) ( F i g u r e 9 ) , the sands range from a r g i l l a c e o u s , immature t o submature, c h e r t a r e n i t e s t o mature q u a r t z a r e n i t e s ( F i g u r e 17), p l o t t i n g on the q u a r t z - c h e r t j o i n . C h e r t , q u a r t z , p o l y -c r y s t a l l i n e q u a r t z , and rock fragments a r e the p r i n c i p a l sand s i z e c o n s t i t u e n t s and k a o l i n i t e and i l l i t e a r e the dominant c l a y s . A c c e s s o r y m u s c o v i t e i s common i n the f i n e r and muddier s a n d s t o n e s . In F i g u r e 17B, the p e r c e n t a g e of the t h r e e p r i n -c i p a l framework componants a r e p l o t t e d f o r 85 samples of the D r u m h e l l e r s a n d s t o n e . Cements c o n s i s t of s i d e r i t e , s i l i c a , c a l c i t e , d o l o m i t e , b a r i t e , and p y r i t e ; the l a s t f o u r o n l y i n minor amounts. C o a l i f i e d p l a n t d e b r i s i s common, and o u t l i n e s s e dimentary s t r u c t u r e s . The two end members of the u n i t can be d i f f e r e n t i a t e d best by v a r i a t i o n s i n framework g r a i n s . The D r u m h e l l e r sandstones i n the s t u d y a r e a , a r e s i m i l a r t o the Success Sandstones i n s o u t h w e s t e r n Saskatchewan de-s c r i b e d by C h r i s t o p h e r (1974) as "white and l i g h t g r e e n , k a o l i n i n d u r a t e d , q u a r t z o s e sandstones and s i l t s t o n e s , w i t h abundant t o minor amounts of f e l d s p a r , s p h a e r o s i d e r i t e , c h e r t , and carbonaceous fragments", and t o J u r a - C r e t a c e o u s sands i n the M e d i c i n e R i v e r a r e a , d e s c r i b e d by Hopkins (1981) as "moderately t o p o o r l y s o r t e d , medium t o f i n e g r a i n e d sand-58 P l a t e 2. P e t r o l o g y of the D r u m h e l l e r Sandstones. A.& B. Angu l a r and rounded q u a r t z and c h e r t g r a i n s i n a c l a y m a t r i x w i t h a u t h i g e n i c s i d e r i t e , t y p i c a l of the B a s a l Q u a r t z sandstones (x64, 6-22-27-20 W4, 1365.1 m e t r e s ) . C. P o o r l y s o r t e d q u a r t z o s e , sandy, s i l t s t o n e of the B a s a l Quartz u n i t , (x257, 10-24-28-21 W4, 1438.3). D. D e t r i t a l q u a r t z g r a i n d e r i v e d from an o l d e r , s i l i c a cemented sandstone, i n a p o o r l y s o r t e d , a r g i l l a c e o u s l i t h a r e n i t e , (x64, 14-10-27-20 W4, 1402.8 m e t r e s ) . Quartz and Metaquartzite Rock Fragments Ch«r t F i g u r e 1 7 . A . P e t r o g r a p h i c c l a s s i f i c a t i o n o f t h e L o w e r M a n n v i l l e s a n d s t o n e s i n s o u t h e a s t e r n A l b e r t a , a f t e r W i l l i a m s ( 1 9 6 3 ) . S a n d s t o n e s f r o m t h e D r u m h e l l e r u n i t i n t h e s t u d y a r e a p l o t o n t h e q u a r t z - c h e r t j o i n . B . A t r i a n g u l a r d i a g r a m i l l u s t r a t i n g t h e c o m p o s i t i o n o f t h e f r a m e w o r k g r a i n s i n t h e D r u m h e l l e r S a n d s t o n e s . 60 s t o n e s , muddy sa n d s t o n e s , and sandy mudstones ( w i t h ) q u a r t z , c h e r t , and p o l y c r y s t a l l i n e q u a r t z (as) the p r i n c i p a l sand-s i z e d c o n s t i t u e n t s and k a o l i n i t e as the p r i n c i p a l c l a y " . Framework G r a i n s L i g h t grey c h e r t and q u a r t z g r a i n s form the p r i n c i p a l d e t r i t a l component of the sands, w i t h c h e r t t y p i c a l l y found i n g r e a t e r abundances i n the s t r a t i g r a p h i c a l l y lower sands and q u a r t z i n the upper sands. Chert g r a i n s e x h i b i t a u n i f o r -mly f i n e m i c r o c r y s t a l l i n e t e x t u r e and l a c k r e l i c t c a r b o n a t e t e x t u r e s . Some g r a i n s c o n s i s t of a c o m b i n a t i o n of m i c r o c r y s -t a l l i n e q u a r t z and megaquartz. Chert g r a i n s a r e t y p i c a l l y a n g u l a r t o s u b a n g u l a r , and a r e o c c a s i o n a l l y zoned by wea-t h e r i n g or d i a g e n e t i c o x i d a t i o n ( P l a t e s 3 and 4 ) . P o t a s s i u m r i c h c h e r t s were d e t e c t e d by s t a i n i n g . Chalcedony g r a i n s , d i s p l a y i n g a c h a r a c t e r i s t i c f i b r o u s h a b i t , a r e i n c l u d e d w i t h c h e r t g r a i n s . Quartz g r a i n s range from f i n e a n g u l a r t o medium w e l l rounded sand d i s p l a y i n g worn o v e r g r o w t h s . A n g u l a r i t y can be secondary through the development of q u a r t z o v e r g r o w t h s . G r a i n s a r e r e l a t i v e l y i n c l u s i o n - f r e e and a r e bo t h f r o s t e d and c l e a r . The q u a r t z g r a i n s can be g e n e t i c a l l y c l a s s i f i e d as common ( p l u t o n i c ) , r e c r y s t a l l i z e d metamorphic, and s t r e t c h e d metamorphic, common b e i n g the most abundant. E u h e d r a l z i r c o n i n c l u s i o n s were d e t e c t e d i n one q u a r t z g r a i n i n SEM examina-t i o n . A l l forms of g r a i n c o n t a c t s were o b s e r v e d , and both undulose and s t r a i g h t e x t i n c t i o n . Some g r a i n edges are f u z z y , s u g g e s t i n g some s o l u t i o n of q u a r t z d u r i n g d i a g e n e s i s . From 61 P l a t e 3. Framework g r a i n s i n the D r u m h e l l e r ( B a s a l Q u a r t z ) Sandstone; A. D e t r i t a l c h e r t ( c r o s s e d p o l a r i z e r s , x257, 10-14-27-20 W4, 1381.9 m e t r e s ) , and B. Ch e r t w i t h an a l t e r a t i o n h a l o , ( p l a n e l i g h t , x257, 14-10-27-20 W4, 1393.2 metres) . 62 Plate 4. Framework grains in the Drumheller Sandstone. A. Well rounded quartz in texturally immature sandstone, (x257, 6-22-27-20 W4, 1369.4 metres). B. Forms of chert, chalcedony and fine microcrystalline, in the Basal Quartz sandstones, (x257, 14-10-27-20 W4, 1406.0 metres). 6 3 textural evidence, i t i s inferred that more than one source must have contributed to the quartz component of the sands, one being a former s i l i c a cemented sandstone with well rounded quartz grains. Rock fragments other than chert comprise 0 to 20 percent of the t o t a l volume of any selected sample. D e t r i t a l a r g i l -l i t e grains are common and are characterized by a brown colour in plane l i g h t . They are nearly opaque with flecks of higher birefringence micas v i s i b l e under crossed p o l a r i z e r s . These grains could occasionally be confused with fine micro-c r y s t a l l i n e chert grains. Soft syn-sedimentary clay c l a s t s or p e l l e t s exhibiting l i t t l e mechanical strength show the ef-fects of compaction in the Drumheller sandstones. Metamorphosed quartz arenite grains, consisting of elongate, crenulated quartz c r y s t a l s , (Plate 5) occur in minor amounts. Rounded sedimentary rock fragments, composed of rounded and angular quartz in an argillaceous matrix, indicate derivation of at least part of the Drumheller sands from a pre-existing well-indurated sediment. Greater volumes of a r g i l l i t e and metasedimentary rock fragments are associated with the chert arenite, and rounded, p a r t i a l l y cemented quartz and sedimen-tary rock fragments with the quartz arenites. Gradations be-tween end members e x i s t . Heavy minerals are minor, and include zircon, sphene, tourmaline, and epidote. This suite has led some authors to conclude an eastern cratonic source for much of the Drumheller sediment (Williams, e t . a l . , 1962; Williams, 1963). 64 P l a t e 5. Framework g r a i n s i n the D r u m h e l l e r ( B a s a l Q u a r t z ) sandstone. A. A r g i l l a c e o u s rock fragments, arrow p o i n t s t o fragment boundary, ( c r o s s e d p o l a r i z e r s , x257, 14-10-27-20 W4, 1398.1 m e t r e s ) , B. Mud c l a s t s ( p l a n e l i g h t , x 156, 14-10-27-20W4, 1398.1 m e t r e s ) , C. Metamorphosed q u a r t z a r e n i t e g r a i n s ( c r o s s e d p o l a r i z e r s , x64, 10-22-27-21W4, 1344.1 m e t r e s ) , and D. Sedimentary rock fragments ( p o l a r i z e d l i g h t , x257, 14-10-27-20 W4, 1402.8 m e t r e s ) . 65 Cements Cements within the Drumheller sandstones w i l l be d i s -cussed in the chapter on diagenesis. Only the form of the cements as they relate to t o t a l composition of the sands w i l l be discussed here. The majority of the sandstones are indurated by clays. Carbonate, s i l i c a , barite and pyrite occur in lesser amounts. S i d e r i t e , dolomite, and c a l c i t e are present in variable amounts, with the f i r s t being volumetrically the most s i g n i -f i c a n t . The carbonates have several habits: (1) replacements of d e t r i t a l grains to form microconcretions, (2) cryptocrys-t a l l i n e cement in i n t e r s t i t i a l pores, (3) large c r y s t a l s poi-k i l i t i c a l l y enclosing d e t r i t a l grains, (4) euhedral c r y s t a l s in pores, and less commonly as (5) fine c r y s t a l s in the matrix (Plate 6). S i d e r i t e i s also found as spherulites, 0.2 to 1.0 mm in diameter, commonly displaying a f i b r o r a d i a l habit. The central zone may be darkened with f e r r i c oxides which may also form roughly concentric banding, reminiscent of o o l i t i c textures. Some spherulites do not reveal any nuc-leus but have enclosed clay aggregates and grains of d e t r i t a l quartz in their growth. The apparent absence of a nucleus may be a function of thin section orientation. The various tex-tures are i l l u s t r a t e d in Plate 7. Well developed syntaxial growth of quartz was noted in various zones which lack clay matrix and have good porosity. Inclusions in overgrowths are rare. The recognition of s i l i c a cement was based upon c r y s t a l terminations in pore spaces and 66 Plate 6. Carbonate cements in the Drumheller Sandstone. A. Authigenic dolomite (bladed grains), and s i d e r i t e cement (plane l i g h t , x 39, 8-22-27-20 W4, 1372.2 metres) . B. Euhedral s i d e r i t e grains enclosed in pore f i l l i n g c a l c i t e cement (red st a i n ) , (crossed polarized l i g h t , x257, 12-22-27-20 W4, 1366.7 metres). 67 Plate 7. Habits of authigenic s i d e r i t e . S i d e r i t e is found as; A, spherulites enclosing fine grains of quartz (plane l i g h t , x64, 10-23-27-20 W4, 1379.2 metres), B, spherulites composed of fine radiating c r y s t a l s which give a strong o p t i c a l extinction cross under cross polarized l i g h t (x64, 14-10-27-20 W4, 1395.9 metres), C, spherulites darkened with f e r r i c oxides producing a concentric pattern reminiscent of o o l i t h i c texture (plane l i g h t , x64, 14-10-27-20 W4, 1395.9 metres), and as D, small euhedral c r y s t a l s (plane l i g h t , x64, 12-22-27-20 W4, 1366.7 metres). 68 o c c a s i o n a l d ust rims on d e t r i t a l g r a i n s . P r e s s u r e s o l u t i o n was absent t o moderate. W e l l c r y s t a l l i z e d b a r i t e cement was o b s e r v e d a s s o c i a t e d w i t h s i d e r i t e and c l a y pore f i l l i n g s . As i l l u s t r a t e d i n P l a t e 8, b a r i t e does not c o r r o d e d e t r i t a l q u a r t z or r e p l a c e s i -d e r i t e . SEM e x a m i n a t i o n of the c o n t a c t r e l a t i o n s r e v e a l e d a t h i n f i l m of c l a y s between the q u a r t z and b a r i t e , and a smooth c o n t a c t between b a r i t e and c a r b o n a t e . I n c l u s i o n s of c a r b o n a t T e r a p a t i t e were d e t e c t e d i n the b a r i t e . P y r i t e , as a replacement a u t h i g e n i c cement, o c c u r s as m a c r o s c o p i c a l l y v i s i b l e n o dules as w e l l as f r a m b o i d s and w e l l c r y s t a l l i z e d cubes i n the m a t r i x ( P l a t e 9 ) . Ma t r i x M a t r i x of the D r u m h e l l e r sandstones i s composed domi-n a n t l y of c l a y , w i t h minor amounts of s i l t - s i z e d q u a r t z . X-ray d i f f r a c t i o n a n a l y s i s of o r i e n t e d c l a y s l i d e s t aken from the D r u m h e l l e r u n i t i n d i c a t e d the presence of k a o l i n i t e , oc-c a s i o n a l i l l i t e , q u a r t z , s i d e r i t e , and h a l l o y s i t e i n the ma-t r i x . P o t a s s i u m i o n s d e t e c t e d i n the m a t r i x by s t a i n i n g pos-s i b l y i n d i c a t e an abundance of i l l i t e i n s e l e c t e d zones. The presence of the c a l c i u m i o n i n m a t r i x c l a y s was s i m i l a r l y d e t e c t e d . In s e v e r a l samples d i s t i n c t l i n i n g of pore spaces by c l a y was n o t e d , i n d i c a t i v e of an a u t h i g e n i c o r i g i n ( P l a t e 10). SEM a n a l y s i s c o n f i r m e d t h i s o b s e r v a t i o n . D u c t i l e mud c l a s t s were compressed between g r a i n s t o the p o i n t where they ar e i n d i s t i n g u i s h a b l e from m a t r i x c l a y s , e x cept by c o l o u r 69 P l a t e 8. S i l i c a and b a r i t e cements i n the D r u m h e l l e r s a n d s t o n e s . A. Qu a r t z overgrowth, (x64, 10-28-27-20 W4, 1354.5 m e t r e s ) . B. Development of s y n t a x i c a l q u a r t z i s r e c o g n i z e d m a i n l y by shape and presence of dust r i m s , (x257, 6-22-27-20 W4, 1377.6 m e t r e s ) . C. W e l l c r y s t a l l i z e d b a r i t e pore f i l l i n g cement e n c l o s i n g s i d e r i t e s p h e r u l i t e s , (x64, 14-15-27-20 W4, 1366.4 m e t r e s ) , D. B a r i t e pore f i l l , (x257, 14-15-27-20 W4, 1366.4 m e t r e s ) . 70 # Plate 9. Authigenic pyrite as; A, macroscopic nodules replacing matrix, (x64, 14-15-27-20, 1373.1 metres), B, as framboids, (x257, 14-10-27-20 W4, 1392.2 metres), C, as euhedral c r y s t a l s , (x64, 6-36-29-21 W4, 1382.2 metres), and D, f i l l i n g the cores of s i d e r i t e spherulites (x257, 6-22-27-20 W4, 1365.1 metres). 71 P l a t e 10. The m a t r i x of the B a s a l Quartz sandstone c o n s i s t s o f ; A, c l a y s , (x257, 18-22-27-20 W4, 1374.3 m e t r e s ) , B, o r g a n i c m a t t e r , (x64, 10-22-27-21 W4, 1345.9 m e t r e s ) , and C, h e m a t i t i c c l a y , (x64, 7-20-27-21 W4, 1429.5 m e t r e s ) . Compressed c l a y p e l l e t s and mud c l a s t s can be c o n f u s e d w i t h m a t r i x , as i n D, (x257, 14-10-27-20 W4, 1404.7 m e t r e s ) . 72 differences. Organic material in the form of c o a l i f i e d plant remains is common in the matrix of the sandstones. In oxi-dized beds, hematite dispersed in the clay matrix imparts a red colour to the unit. Single grain coatings of hematite were not recognized, suggesting the iron was transported into the system with clays. Stratigraphic D i s t r i b u t i o n of Petrographic Components The v e r t i c a l d i s t r i b u t i o n of quartz, rock fragments, matrix, carbonate cement and porosity have been plotted for nine core locations (Figures 18 to 27). The chert content of the sandstones generally shows an inverse relationship with the amount of quartz in a sample. The d i s t r i b u t i o n of a r g i l -laceous rock fragments with depth tends to p a r a l l e l chert content in most cases. The volume of authigenic carbonate cement i s greatest in finer sediments or in sandstones adja-cent to shale interbeds, possibly indicating a genetic r e l a -tionship. In some cores the estimated porosity percentages with depth p a r a l l e l that of the carbonate cements; eg, 6-22-27-20W4, 9-14-28-21W4, and 7-23-28-21W4, suggesting a r e l a -tionship between the two. 5.2.4. Geophysical Log Response The log response of the Drumheller Sandstone unit re-f l e c t s the sandy nature of the sediment. Blocky, upward fin i n g , and upward coarsening sequences were noted (Figures 15 and 16). The gamma log p r o f i l e s are not everywhere diagno-CAIRNE ET AL WAYNE 14-10-27-20W4 1386.5 - 1423m (4546.1 - 4667.4ft) x » £ w L i t h o l o g y U l 4> O E 1386 H 1390 1396 ^ 1400 1406 14 10 H 14 16-1 1420 m '...j, Q u a r t z % C h e r t % R o c k F r a g m e n t s % M a t r i x % C a r b o n a t e C e m e n t % P o r o s i t y o <u > O C o m m e n t s 0 10 203040 50 60 70 -0 10 20 3040 60 60 70 0 10 2030 0 10 20304060 0 10 20304060 0 10 20 30 40 1 I I I I I I I . L _ J I I I 1 I I , I I I I , I I l _ l I I , L _ J I I I I , I I I I I - K a o l l n l t e - K a o l l n l t e . U t i l e F i g u r e 18. The v e r t i c a l d i s t r i b u t i o n of major framework g r a i n s , m a t r i x , p o r o s i t y and c a r b o n a t e cement i n 14-10-27-20 W4, 1386.5-1423.0 m e t r e s . HIGHFIELD ET AL WAYNE 14-15-27-20W4 1357.6 - 1394.5m (4453 - 4574ft) 1 2 O E 1360 L i t h o l o g y Q u a r t z C h e r t % R o c k F r a g m e n t s % M a t r i x % C a r b o n a t e C e m e n t P o r o s i t y 1370 1376-1 1360 1386 -t 1300H 0 1 0 2 0 3 0 4 0 6 0 6 0 7 0 0 10 2 0 3 0 4 0 6060 70 0 10 2 0 3 0 0 10 2 0 3 0 4 0 60 0 10 2 0 3 0 4 0 6 0 0 1 0 2 0 3 0 4 0 I I i I I I I I . I I I I . L_ l I—I—l_J . I—I—I—I—I—I . I—I I I—I I 1 l_ J 1_ V \ C o m m e n t s l«V KL-Ott. zone, continental -Barren, transitional -Kaollnlte Kaollnlte. IIHte berlte,cement Pyrlte cement 6% Kaollnlle. pyrlle cement 3* -Kaollnlte . Illlle Kaollnlle. Illlle -Kaollnlte -Kaollnlte. Illlte . zoned carbonate oolds -Kaollnlte F i g u r e 1 9 . T h e v e r t i c a l d i s t r i b u t i o n o f m a j o r f r a m e w o r k g r a i n s , m a t r i x , p o r o s i t y a n d c a r b o n a t e c e m e n t i n 1 4 - 1 5 - 2 7 - 2 0 W4, 1 3 5 7 . 6 - 1 3 9 4 . 5 m e t r e s . GRT PLNS TRI SOC CPR WAYNE A NO 6 22 6-22-27-20W4 1351.8 - 1385m (4434 - 4543ft) X •> UJ o Q £ 13SS 1 3 e o ^ 1 3 6 9 1370 137SH 1380-1 138S-J L i t h o l o g y % Q u a r t z % C h e r t % R o c k F r a g m e n t s % M a t r i x % C a r b o n a t o C e m e n t o % P o r o s i t y C o m m e n t s 0 1 0 2 0 3 0 4 0 6 0 6 0 70 0 10 2 0 3 0 4 0 6060 70 0 1 0 2 0 3 0 0 10 2 0 3 0 4 0 6 0 0 10 2 0 3 0 4 0 6 0 0 10 20 30 40 I IJ I O | 1 1 1 I I I -I . 1... I I I 1-1 1 I I I I I I I I I I £ ~ Carbonate oolds F i g u r e 2 0 . T h e v e r t i c a l d i s t r i b u t i o n o f m a j o r f r a m e w o r k g r a i n s , m a t r i x , p o r o s i t y a n d c a r b o n a t e c e m e n t i n 6 - 2 2 - 2 7 - 2 0 W4, 1 3 5 1 . 8 - 1 3 8 5 . 0 m e t r e s . SOC GRT PLNS TRI CPR WAYNE NO 22-8 8-22-27-20W4 1351.8 - 1380.4m (4434 - 4528ft) 1 2 0- *-ui 2 Q E 1350 -1 1355 ' L i t h o l o g y % Q u a r t z 10 2 0 3 0 4 0 60 60 70 I I L_l I L-1 1305 1370 H 1375 1380 1386 ^3C C h e r t 10 20 3040 60 60 70 I • ' I I 1 I % R o c k F r a g m e n t s 10 2030 I I I % M a t r i x 10 2 0 3 0 4 0 50 _J I I I I % C a r b o n a t e C e m e n t I 10 20 3 0 4 0 60 I I I i I % P o r o s i t y ) 10 20 30 40 I I I I—I <P > o C o m m e n t s Kaollnlte, Illlle. very line grained -Kaollnlte Kaollnlle Kaollnlle Kaollnlte Kaollnlte F i g u r e 2 1 . T h e v e r t i c a l d i s t r i b u t i o n o f m a j o r f r a m e w o r k g r a i n s , m a t r i x , p o r o s i t y a n d c a r b o n a t e c e m e n t i n 8 - 2 2 - 2 7 - 2 0 W4, 1 3 5 1 . 8 - 1 3 8 0 . 4 m e t r e s . , —j. M O B I L E T A L W A Y N E 1 0 - 2 3 M U - 2 7 - 2 0 W 4 1 3 4 9 . 1 - 1 3 7 9 . 8 m ( 4 4 2 5 - 4 5 2 6 f t ) 0. ~ UJ » O E 1 3 5 0 -H 1 3 6 0 1365 -{ 1 3 7 0 1376 -J 1380 H L i t h o l o g y % Q u a r t z 0 10 2 0 3 0 4 0 5 0 6 0 7 0 1 I I I I I I I % C h e r t 0 10 2 0 3 0 4 0 60 60 70 I I 1 I I I I I % R o c k F r a g m e n t s 0 10 2 0 3 0 I I L_ l / % M a t r i x 0 10 2 0 3 0 4 0 6 0 I I I I I I % C a r b o n a t e C e m e n t 0 10 2 0 3 0 4 0 6 0 I—I I I l I % P o r o s i t y 0 10 20 3 0 40 I I I I I IP > O C o m m e n t s Carbonate oolda Siderite concretlona Figure 22. The v e r t i c a l d i s t r i b u t i o n of major framework grains, matrix, porosity and carbonate cement in 10-23MU-27-20 W4, 1349.1 - 1378.8 metres. L I E D T K E Z A P A T A H U S S A R 7 - 2 - 2 7 - 2 1 W 4 1 4 1 2 . 5 - 1 4 4 1 . 5 m ( 4 6 3 3 - 4 7 2 8 ft ) x « Ul 9) O E L i t h o l o g y m JUL p 1 0 ) % Q u a r t z O 10 2 0 3 0 4 0 60 80 70 I l l % C h e r t 0 10 20 3040 60 60 70 1 I I I I 1 I .1 % R o c k F r a g m e n t s 0 10 20 30 1 i i i % M a t r i x 0 10 20 3040 60 1 1 I I I I % C a r b o n a t e C e m e n t 0 10 20 3040 60 1 i i I I I % P o r o s i t y 0 10 20 30 40 L I I I I > o C o m m e n t s [4 KL-Con l lnen ta l [A Barren - Kao l ln l l e . Ut i le , hematite matr ix , very angular oralne JA KL-Cont lnenta l . plant f ragments -Abundant py r l l e F i g u r e 2 3 . T h e v e r t i c a l d i s t r i b u t i o n o f m a j o r f r a m e w o r k g r a i n s , m a t r i x , p o r o s i t y a n d c a r b o n a t e c e m e n t i n 7 - 2 - 2 7 - 2 1 W4, 1 4 1 2 . 5 - 1 4 4 1 . 5 m e t r e s . T G T R O S E D A L E 7 - 1 7 - 2 8 - 2 0 W 4 1 3 7 1 ; 9 - 1 3 9 7 . 9 m ( 4 5 0 0 - 4 5 8 5 f t ) 1 2 t s S E 1 3 7 8 H 1 3 8 0 H 1 3 8 5 1 3 9 0 -1 3 9 5 1 4 0 0 -L i t h o l o g y % Q u a r t z 0 10 2 0 3 0 4 0 50 6 0 7 0 1 I I I I I I I % C h e r t 0 10 2 0 3 0 4 0 60 60 70 I I I I I I % R o c k F r a g m e n t s o 10 20 3 0 t i l l % M a t r i x 0 10 2 0 3 0 4 0 6 0 I I I I I I % C a r b o n a t e C e m e n t 0 10 2 0 3 0 4 0 60 i I I I i I > % P o r o s i t y 0 10 20 30 40 1 I I I I x : * o I -o> > o C o m m e n t s - P y r l l e f m m b o l d * - 1 5 % b a r i t e c e m e n l K a o l l n l l e A B a r r e n F i g u r e 2 4 . T h e v e r t i c a l d i s t r i b u t i o n o f g r a i n s , m a t r i x , p o r o s i t y a n d 7 - 1 7 - 2 8 - 2 0 W4, 1 3 7 1 . 9 - 1 3 9 7 . 9 m a j o r f r a m e w o r k c a r b o n a t e c e m e n t i n m e t r e s . «^ U3 M O B I L N W W A Y N E 1 1 - 2 - 2 8 - 2 1 W 4 1 4 1 5 . 5 - 1 4 5 3 . 3 m ( 4 6 4 3 - 4 7 6 7 f t ) Q E 1420H 1425H 1430-J 1435-1 1440 H 1449 1460H Lithology ^ 5 % Quartz % Chert % Rock Fragments Matrix % Carbonate Cement Porosity o Comments 0 10 2 0 3 0 4 0 60 8 0 7 0 0 10 2 0 3 0 4 0 60 60 70 0 10 2 0 3 0 0 1 0 2 0 3 0 4 0 6 0 0 10 2 0 3 0 4 0 6 0 0 1 0 2 0 3 0 4 0 1 i I I I I I I . I I I I I I I I . I I I I , I I I I I I . I I I I I I . I L J I—I •--7 •Very line -Kaollnlle. Illlle alderlle -Kaollnlte. Illlle Carbonate mud F i g u r e 2 5 . T h e v e r t i c a l d i s t r i b u t i o n o f m a j o r f r a m e w o r k g r a i n s , m a t r i x , p o r o s i t y a n d c a r b o n a t e c e m e n t i n 1 1 - 2 - 2 8 - 2 1 W4, 1 4 1 5 . 5 - 1 4 5 3 . 3 m e t r e s . 00 o C P O G W A Y N E 9 - 1 4 - 2 8 - 2 1 W 4 14 1 6.2 - 1 4 4 6 . 6 m ( 4 6 4 5 - 4745f t ) I » £.£ Lithology IXJ <B a E 1420 1428 H 1430H 143B H 1440 1 4 4 S H 1450-% Quartz % Chert % Rock Fragments Matrix % Carbonate Cement Porosity > O Comments A A A A i M A A A) 0 10 20 30 40 60 60 TO 0 10 20 3040 60 60 70 0 10 20 30 0 10 20 30 4 0 60 0 10 20 30 40 60 0 10 20 30 40 ' N I—1 I l_J 1 1 1 , I I I I I I I I . I I I I . I I I I I I . I I I I I I , , n cr -Hemati te In matrix Figure 26. The v e r t i c a l d i s t r i b u t i o n of major framework grains, matrix, porosity and carbonate cement in 9-14-28-21 W4, 1416.2-1466.6 W4 metres. CD C P O G W A Y N E 7 - 2 3 - 2 8 - 2 1 W 4 1 4 3 9 . 9 - 1 4 6 8 . 9 m ( 4 7 2 3 - 4 8 1 8 f t ) 1 2 • i t <L> o £ 1440 1450 1455 1480 H 1470H Lithology to % Quartz 6 10 203040 SO 60 70 I I I I I I—I—I % Chert 0 10 20 30 40 60 60 70 I I I I I I I I % Rock Fragments 0 10 2030 1 I I I % Matrix 0 10 203040 60 I I l_J I I % Carbonate Cement 0 10 203040 60 1 i i i I I % Porosity 0 10 20 30 40 1 I I I I Comments |A KL-Contlnenlal. plant & fish Iragmanta -Kaollnlte. Illlte -Limestone F i g u r e 2 7 . T h e v e r t i c a l d i s t r i b u t i o n o f g r a i n s , m a t r i x , p o r o s i t y a n d 7 - 2 3 - 2 8 - 2 1 W4, 1 4 3 9 . 9 - 1 4 6 8 . 9 m a j o r f r a m e w o r k c a r b o n a t e c e m e n t i n , m e t r e s . op 83 s t i c of subtle changes in li t h o l o g y . Natural gamma ray logs respond to gamma rays produced in the process of radioactive decay of naturally occurring minerals, mainly "°K contained within clays. In the Drumheller sandstones, where ka o l i n i t e i s the dominant clay, zones r i c h in clay w i l l not be se-parable from zones lacking clay due to the absence of "°K in ka o l i n i t e . Distorted impressions of the statigraphy may be formed. For proper evaluation of the Drumheller lithology from geophysical well logs, a combination of tools must be used. On gamma-ray logs, marked deflections, recording API units s i g n i f i c a n t l y higher than the shale base l i n e , commonly define the top of Drumheller sandstone beds, or separate beds of d i f f e r i n g l i t h o l o g y . In cores, these deflections correlate with zones in which the sandstone has been completely ce-mented by pyri t e , possibly marking an unconformable contact (Figure 15, 10-8-29-22W4, Figure 16, 10-22-27-20W4 and 10-14-28-21W4). 5.2.5. Dist r i b u t i o n and Thickness Drumheller sandstone is absent in the northwest corner of the study area where Calcareous Member sediments rest d i -r e c t l y upon the De v i l l e Formation or Mississippian s t r a t a . Elsewhere the sandstone forms a widespread blanket ranging up to 47 m in thickness. On the isopach map (Map 7), elongated thick areas are separated by subparallel thin areas. A three dimensional plot of the isopach i s presented in Figure 28. 84 Figure 28. Three dimensional representation of the Drumheller Sandstone (Basal Quartz) isopach. The sandstones are absent in the northwestern part of the area and f i l l in pre-Cretaceous hollows in the east. 85 The. isopach pattern appears to r e f l e c t depositional variations in thickness with some modification by post-depos-i t i o n a l erosion. This is suggested by the corr e l a t i o n of f a -ci e s , as interpreted from geophysical logs and core, with paleotopography. Where lowlands are suggested, homogenous valley f i l l deposits are found. Flanking highlands, the sand-stones grade into interbedded s i l t s and sands. If the present Drumheller Sandstone d i s t r i b u t i o n was controlled only by post-depositional erosion, isopach thin portions would not necessarily correlate with paleohighs and fine sediment, or thicks with paleolows and sand accumulation. Figure 29 i s a cartoon s i m p l i f i e d from section number 3 (Appendix IX), i l l u -s t r a t i n g the d i s t r i b u t i o n of sand and s i l t of the Drumheller sandstone unit. Thickest sands, capped by s i l t s , are in v a l -leys. Figure 30, cross-section 1, i l l u s t r a t e s Drumheller sandstones grading l a t e r a l l y into Calcareous Member sediments at the western edge of the sand sheet. A relationship between thickness and lithology was de-tected. Where the unit is thickest, i t is composed of fine to medium grained sandstone, with a s i l t s t o n e cap. Where thin and deposited on the flanks of paleohighs, the Drumheller Sandstone unit i s composed of interbedded fine sandstones and coarse s i l t s t o n e s , with redbeds being common. The edge of the Drumheller Sandstone unit i s inconsis-tent with the paleotopography and thus probably related to a facies change and contemporaneous erosion. The irregular upper contact of the Drumheller Sandstone NW S E i D a t u m k m . F i g u r e 2 9 . D i s t r i b u t i o n o f t h e D r u m h e l l e r S a n d s t o n e , c r o s s -s e c t i o n 3. T h e s a n d s t o n e s h e e t i s t h i c k e s t i n p a l e o v a l l e y s d e f i n e d b y t h e p r e - C r e t a c e o u s u n c o n f o r m i t y a n d i s l o c a l l y h y d r o c a r b o n b e a r i n g . T h e s a n d s h e e t i s c a p p e d u n i f o r m l y b y a s i l t s t o n e . CO SW NE i i i km. F i g u r e 3 0 . D i s t r i b u t i o n o f t h e D r u m h e l l e r S a n d s t o n e , C r o s s -S e c t i o n 1. T h e s a n d s l a t e r a l l y i n t e r f i n g e r w i t h f i n e s e d i m e n t o f t h e C a l c a r e o u s M e m b e r . CO . 88 unit may r e f l e c t preservation of incised r i v e r terraces. The quartzose sandstones are s t r a t i g r a p h i c a l l y younger than the chert arenites and wackes, but may be preserved in erosional valleys cut below older chert sands, leading to a complex d i s t r i b u t i o n of individual sand packages. 5.2.6. Deposition of the Drumheller Sandstone Drumheller sandstones f i l l , in part, a valley system of moderate dimensions cut into Paleozoic carbonates and shales. Non-marine deposition is suggested by the coal content, reco-very of pollen and spores, lack of marine faunal indicators, presence of red beds, absence of glauconite, and formation of s i d e r i t e rather than pyrite as an early authigenic cement. Kaol i n i t e , abundant in the Drumheller sandstone, i s commonly associated with non-marine sediments (Matsuamoto and Iijima, 1981). The sedimentological character of the unit changes within the study area from thick accumulation of massive or planar bedded, fine to medium grained, uniform sandstone in the east, to small coarsening upward sequences at the western margin of the sand blanket. In the eastern section of the study area, thick se-quences of poorly sorted, uniform sand accumulated over a wide area. The presence of coarsest sediment in paleolows and finer material over paleohighs i s interpreted to r e f l e c t highest energy conditions in paleoval.leys. This d i s t r i b u t i o n can be accounted for by a l l u v i a l processes. Sheets of uni-form, fine to medium grained sand can form where low sinuosi-89 ty meandering r i v e r s , sweeping across a floodplain, build a thick multistory sand body by coalescing point bars (Campbell, 1976). The successive d i v i s i o n and rejoining of flow around migrating a l l u v i a l islands and bars in low sinuo-s i t y , sandy, braided r i v e r s would produce a similar geometry. The l a t t e r interpretation seems better to f i t the fea-tures of the Drumheller sandstones. A high sand-shale r a t i o as in these sediments i s t y p i c a l of braided stream deposits. V e r t i c a l accretionary fines deposited during flooding are eroded quickly due to the rapid and quasi-continous nature of braid channel migration permitted by eas i l y erodible banks and lack of clay plugs. Fining upward sequences characteris-t i c of point bars are rare in the Drumheller unit; rather a sudden change from buff or grey sandstone to grey and red si l t s t o n e at the top of the member i s common. The quartzose s i l t s t o n e s can be interpreted as the product of channel aban-donment by avulsion or drowning. The presence of a few fi n i n g upward sequences i s consistent with the braided r i v e r i n t e r -pretation. Cant (1973) interpreted Devonian strata containing f i n i n g upward cycles as braided stream deposits, and Gustavson (1974) described f i n i n g upward lenses from present braided g l a c i a l outwash. The thickness of the a l l u v i a l sand unit (0 to 47 m), compares well with modern and ancient braided r i v e r complexs. Kessler (1971, c i t e d in Campbell, 1976) and Ore (1974, c i t e d in Campbell, 1976) stated that braided streams form sheet-l i k e deposits up 30 m thick. Coleman (1969) reported the 90 average depth of sand accumulation in a 13 km wide channel of the Brahmaputra River as approximately 18 m with 37 m at node points. The Westwater Canyon Complex in the Morrison Formation (Jurassic), northwestern New Mexico, which averages 61 m in thickness, was interpreted by Campbell (1976) as a braided rive r deposit. Horizontally s t r a t i f i e d and current rippled sandstones, common in the point bar sequence (Walker 1982, c i t e d in Harms et a l . , 1982), are rare in the Drumheller unit, with planar tabular cross bed sets and massive beds common. The planar cross bedded sandstones are interpreted as sand deposited on foresets of longtitudinal or transverse bars migrating at high angles to channel trend. The heterogeneity of textures observed in the Drumheller Sands can be accounted for by differences in depositional " processes within a braided r i v e r . Local intervals of moder-ately well sorted, submature sandstones, lacking s i g n i f i c a n t amounts of clay or s i l t , would be deposited during waning flood stages as basinward sheetflows. These sediments were deposited under upper flow regime conditions as a result of lowered water depths and flow rates associated with widening of channels. Massive, cross-, and horizontal-laminated bed-ding may be preserved. Clay drapes may cover individual flood sequences. Reworking of bar tops may enhance maturity and i n i t i a l porosity. Poorly sorted, bimodal, fine to medium-grained, sandstones, consisting of angular and rounded d e t r i -t a l grains of chert and quartz in a clay matrix, may have 91 formed from mud f l o w s . P o o r l y s o r t e d , c r o s s bedded, m a s s i v e , and s c o u r e d , immature sands, c o a r s e r than the p r e v i o u s l y de-s c r i b e d s a n d s t o n e s , r e p r e s e n t b a c k f i l l d e p o s i t s i n stream c h a n n e l s t e m p o r a r i l y e n t r e n c h e d i n t o the a l l u v i a l p l a i n . These l a t t e r sands comprise over f i f t y p e r c e n t of the t o t a l p r e s e r v e d sand s e c t i o n . Very f i n e g r a i n e d sandstones and sandy s i l t s t o n e s , composed of a n g u l a r framework g r a i n s f l o a -t i n g i n a c l a y m a t r i x , r e p r e s e n t u n s o r t e d m a t e r i a l d e p o s i t e d d u r i n g abandonment of a c h a n n e l or d e p o s i t e d on f l o o d p l a i n s d u r i n g waning f l o o d s t a g e s . Only r e c e n t l y have sandy, b r a i d e d systems r e c e i v e d much a t t e n t i o n i n the l i t e r a t u r e . T h i s r e s u l t s from l a c k of r e c o g -n i t i o n of such d e p o s i t s i n the g e o l o g i c a l r e c o r d and p r e v i o u s emphasis on d e s c r i p t i o n of p o i n t bar sequences. M i a l l (1981) summarized 6 forms of low s i n u o s i t y m u l t i p l e c h a n n e l r i v e r s : T r o l l h e i m t y p e , S c o t t t y p e , Donjek t y p e , South Saskatchewan t y p e , P l a t t e t y p e , and the B i j o u Creek t y p e , r e f l e c t i n g d i f -f e r e n t t e c t o n i c e n v i r o n m e n t s . The f i r s t two a r e composed p r i -m a r i l y of g r a v e l and a r e u s u a l l y a s s o c i a t e d w i t h a l l u v i a l f a n s . The Donjek and South Saskatchewan t y p e s a r e c y c l i c a l d e p o s i t s from g r a v e l l y or sandy systems r e s p e c t i v e l y . The P l a t t e model c o n s i s t s of sand d e p o s i t e d i n l i n g o i d and t r a n s -v e r e s e sandy f o r s e t b a r s i n e x c e p t i o n a l l y b r o ad, s h a l l o w r i -v e r s . In c o n t r a s t t o the South Saskatchewan r i v e r , c y c l e s a r e r a r e l y d e v e l o p e d . The B i j o u Creek type r e s u l t s from sedimen-t a t i o n i n ephermeral or p e r e n n i a l r i v e r s s u b j e c t t o f l a s h f l o o d s . V e r t i c a l p r o f i l e s f o r the t h r e e sandy systems a r e 92 presented in Figure 31. The Drumheller sandstones do not show well developed c y c l i c i t y , and approximate the Pi a t t River model. In the northwest sector of the study area, basal a l l u v i -a l sandstones are absent. At the western margin of the sand-stone sheet, sand sequences coarsen upward, accompanied by small scale f a u l t i n g , slumping and high angle bedding. A thin coal cap is common. The sequences range from 3 to 10m thick. These massive and cross bedded muddy sandstones can be in t e r -preted as the foreset deposits of a Gilbert-type delta. This style of progradation occurs where rivers with shallow chan-nels, transporting material as bedload, deposit sediment in water s i g n i f i c a n t l y deeper than the channel. This interpreta-tion is consistent with the interpretation of depositional environment of the Drumheller sandstone in the eastern part of the study area. The occurrance of fine d e l t a - l i k e se-quences capping thick a l l u v i a l sands as in 5-5-28-22 W4, sug-gests drowning of the a l l u v i a l channel. To understand the relationships between the two deposit-ional processes, a l i t h o f a c i e s map of the Drumheller unit was constructed. Twelve sequences were defined, based on geophy-s i c a l well log interpretation and core contr o l . The d i s t r i b u -tion of these facies was mapped, as presented in Map 9. The 12 facies d e f i n i t i o n s are summarized in Figures 32 to 34. Sequences 1, 2 and 3, r e f l e c t blocky or s l i g h t l y f i n i n g upward channel f i l l s , interpreted as coalescing braid bars. Sequences 2 and 3 are distinguished by the lack of a fine cap -93 S. S A S K A T C H E W A N T Y P E P L A T T E T Y P E BIJOU C R E E K T Y P E Figure 31. The range of facies which could be produced by deposition in a sandy braided r i v e r , in d i f f e r i n g tectonic environments ( M i a l l , 1980). 94 <" 1 . A medium grained, f i n i n g upward j sandstone i s o v e r l a i n by s i l t and \ shale. This sequence i s the r e s u l t j of early channelling followed by ( abandonment (Well 6-18-27-20•W4). 2. A blocky sandstone, deposited by coalescing b r a i d bars, i s overlain by a l i g h t green-grey shale and s i l t s o n e , deposited during channel abandonment (Well 6-10-28-20 W4). 3. This f a c i e s i s i d e n t i c a l to facies 2, but lacks f i n e r sediments capping the homogeneous sands. This lack of fines may be a product of post-depositional erosion or r e f l e c t a very rapid abandonment of the channel system (Well 7-36-27-21 W4). 4. Facies 4 c o n s i s t s of interbedded sandstones and s i l t s t o n e s , the s i l t s t o n e s red-brown, i n d i c a t i v e of oxygenated conditions. This sequence fines upward and has been interpreted as preserved f l o o d p l a i n deposits on the margins of the braid complex, with some minor channelling represented by the thicker sands (Well 6-17-29-20 W4). Figure 32. Drumheller Sandstone l i t h o f a c i e s sequences 1 through 4. 9 5 5. A r e d - b r o w n o r g r e y f l o o d p l a i n s i l t s t o n e i s o v e r l a i n by a f i n i n g u p w a r d t o b l o c k y s a n d s e q u e n c e , i n d i c a t i n g m i g r a t i o n o f t h e m a j o r c h a n n e l o v e r f o r m e r f l o o d p l a i n d e p o s i t s , ( W e l l 1 1 - 3 0 - 2 9 - 2 2 ) . 6. F i n e s a n d s t o n e a n d s i l t s t o n e d o m i n a t i n g i n t h e w e s t e r n s e c t i o n o f t h e D r u m h e l l e r s a n d s h e e t , ( W e l l 3-34-28-22 W4). 7. A c o m b i n a t i o n o f f l u v i a l a n d d e l t a i c p r o c e s s e s i s r e p r e s e n t e d w i t h a f i n i n g upward s e q u e n c e c a p p e d by c o a r s e n i n g upward s a n d s t o n e s ( W e l l 7-17-28-20 W4). L 8. A b l o c k y c h a n n e l f i l l i s c a p p e d by s e v e r a l s m a l l c o a r s e n i n g upward s e q u e n c e s , p o s s i b l y r e p r e s e n t i n g r e p r e s e n t i n g s h i f t i n g d e l t a i c l o b e s o v e r an a l l u v i a l d e p o s i t o r c r e v a s s e s p l a y s ( W e l l 5-5-28-22 W4) . F i g u r e 33. D r u m h e l l e r S a n d s t o n e l i t h o f a c i e s s e q u e n c e s 5 t h r o u g h 8. 96 9. A general coarsening upward sequence with sediments r e f l e c t i n g an a l l u v i a l fan sequence, (Well 10-13-29-20 W4). 10. Several small coarsening upward sequences are recognized representing d e l t a i c processes, lacking evidence for associated f l u v i a l sedimentation (Well 6-23-28-23 W4). 11. A fine sandstone embedded in s i l t s o n e s . This sequence could be re l a t e d to f l u v i a l or d e l t a i c sequences, i n t e r p r e t a t i o n i s ambigious (Well 11-22-28-22 W4). 12; A serrated log p r o f i l e representing f l u c t u a t i n g depositional conditions (Well 7-21-28-21 W4). Figure 34. Drumheller Sandstone l i t h o f a c i e s sequences 9 through 12. 97 on the l a t t e r . Sequence 4 i s interpreted as interbedded sands and s i l t s deposited on channel margins. Sequences 7, 9, 10, and 11 represent combinations of d e l t a i c and f l u v i a l pro-cesses. Sequence 9, an upward coarsening unit, has been i n -terpreted as an a l l u v i a l fan deposit, based on lithology and geomorphic position. The l i t h o f a c i e s map has been interpreted as follows. Draining higher lands in the east, braided a l l u v i a l streams formed the base l e v e l of a l l u v i a l fans. Sandy sediments were deposited by these streams and as l a t e r a l l y extensive sheets on a l l u v i a l plains, draining towards lowlands in the west, interpreted from the facies changes. Maximum accumulation of sediment was in val l e y s . At the western edge of the Drumheller sand sheet, small deltas were b u i l t , indicating progradation of sediment into a standing body of water. The sandstones are absent in the northwestern part of the study area due to non-deposition. Interbedding of D e v i l l e breccias with the Drumheller sandstones indicates deposition of the units in part, contem-poraneously. The development of an extensive sand sheet by a braided complex suggests that vegetation cover was not heavy. 5.2.7. Sediment Source Chert grains in Early Cretaceous sediments have been interpreted to indicate derivation of sediment from a western source area (Glaister,1959). The chert grains of the Drumheller sandstone are l i g h t grey to white, cr y p t o c r y s t a l -98 l i n e and m i c r o c r y s t a l l i n e , i n c o n t r a s t t o the wide range of c o l o u r s and v a r i e t i e s c h a r a c t e r i s t i c of the Kootenany-B l a i r m o r e assemblage. The l a c k of a s s o c i a t e d l i t h i c com-ponents and f e l d s p a r s , s u g g e s t s t h a t the t o t a l c o n t r i b u t i o n of sediment from the west was r e l a t i v e l y s m a l l . The c h e r t s of the D r u m h e l l e r u n i t were p r o b a b l y d e r i v e d l o c a l l y and from the e a s t , from r e s i d u a l d e p o s i t s of the D e v i l l e F o r m a t i o n and c h e r t b e a r i n g P a l e o z o i c r o c k s exposed a t the u n c o n f o r m i t y . The presence of two modes of q u a r t z , w e l l rounded w i t h broken o v e r g r o w t h s , and su b a n g u l a r q u a r t z , s u g g e s t s s e v e r a l s o u r c e s f o r q u a r t z . W e l l rounded q u a r t z g r a i n s were p r o b a b l y d e r i v e d from a t e x t u r a l l y mature, f i n e t o medium g r a i n e d sandstone, cemented i n p a r t by s i l i c a . T h i s c o u l d have been e i t h e r the J u r a s s i c Rosary Sandstone of the Vanguard Group i n sout h w e s t e r n Saskatchewan, or the f i n e t o medium g r a i n e d , q u a r t z o s e sands of the J u r a s s i c Sawtooth F o r m a t i o n i n s o u t h -e a s t e r n A l b e r t a . In the upper beds of the D r u m h e l l e r sand-s t o n e , c h e r t c o n t e n t d e c r e a s e s , and the volume of se d i m e n t a r y rock fragments and sedimentary q u a r t z i n c r e a s e s . T h i s i s i n -t e r p r e t e d t o r e f l e c t u p l i f t and e r o s i o n of e a r l i e r C r e t a c e o u s and J u r a s s i c s t r a t a i n the sou r c e a r e a . Metasedimentary g r a i n s i n the D r u m h e l l e r u n i t c o u l d have been d e r i v e d from the Precambrian S h i e l d t o the e a s t . 99 5.3. ELLERSLIE FORMATION A t h i r d q u a r t z o s e sandstone, p e t r o g r a p h i c a l l y d i s t i n c t from the immature q u a r t z and a r g i l l a c e o u s c h e r t a r e n i t e s of the D r u m h e l l e r Sandstone was r e c o g n i z e d i n c o r e s . These sands c o r r e l a t e w i t h the a l l u v i a l sediments of the E l l e r s l i e F o r m a t i o n , as d e f i n e d by Hunt (1950), G l a i s t e r (1959) and W i l l i a m s (1963), and are c o n s i d e r e d e x t e n s i o n s of t h i s u n i t . 5.3.1. L i t h o l o g y The E l l e r s l i e F o r m a t i o n i n the study a r e a i s composed of i n t e r b e d d e d sands, s i l t s and s h a l e s . The l i g h t grey sands a r e f i n e g r a i n e d , m o d e r a t e l y t o w e l l s o r t e d , mature t o superma-t u r e q u a r t z a r e n i t e s and s u b l i t h a r e n i t e s . Framework g r a i n s c o n s i s t of subrounded t o rounded f i n e q u a r t z , and minor amounts of f i n e - g r a i n e d , rounded c h e r t and p o l y c r y s t a l l i n e q u a r t z , a c c e s s o r y m u s c o v i t e and'heavy m i n e r a l s . D i s t i n c t b i -m o d a l i t y i n g r a i n s i z e was noted ( 6-6-26-19W4, 1412 m e t r e s ) . M a t r i x p ercentage i s v e r y low, c o n s i s t i n g of s i l t s i z e d q u a r t z and c l a y . The sands a r e commonly cemented by q u a r t z , and l e s s commonly by c a l c i t e . E x t e n s i v e p r e s s u r e s o l u t i o n was noted i n s e v e r a l samples. The presence of m u s c o v i t e and the heavy m i n e r a l s u i t e , and s t r a t i g r a p h i c p o s i t i o n , d i s t i n g u i s h t h e s e sands from d e p o s i t s of the C a l c a r e o u s Member. E l l e r s l i e s h a l e s a r e grey t o b l a c k , o f t e n b i o t u r b a t e d , and composed of q u a r t z , k a o l i n i t e and i l l i t e as r e v e a l e d by x-ray d i f f r a c t i o n a n a l y s i s . 100 5.3.2. Geophysical Log Response Geophysical log p r o f i l e s of the E l l e r s l i e Formation re-f l e c t interbedding of thin sands and shales. The top of the formation has been chosen at the f i r s t occurance of fine grained quartzose sandstone below Calcareous Member fine s . The thinness of the unit hinders recognition of f i n i n g or coarsening upwards sequences of the sands on the gamma ray logs. 5.3.3. D i s t r i b u t i o n and Thickness Occurrences of the E l l e r s l i e Formation appear confined to scattered hollows on the Drumheller sandstone. E l l e r s l i e sandstones commonly become incorporated into the Drumheller sandstones, thus an isopach map of the Formation was not con-structed. Thicknessess of 0 to 15 m were noted on geophysical well logs. 5.3.4. Deposition of the E l l e r s l i e Formation Throughout Alberta, various authors have interpreted the depositional environment of the E l l e r s l i e in d i f f e r e n t ways. A marine setting was suggested by Hunt (1950) and Pocock (1962); Gl a i s t e r (1959) and Conybeare (1976) envisioned a d e l t a i c environment; and Williams (1963) suggested non-marine deposition of the E l l e r s l i e sediment. The lack of data on the E l l e r s l i e sediments of the Drumheller area from t h i s study prohibits accurate interpretation of depositional environ-101 ments. The sh a r p b a s a l c o n t a c t of the f o r m a t i o n , w i t h b l a c k s t r u c t u r e l e s s s h a l e s r e s t i n g on w h i t e t o b u f f D r u m h e l l e r s a n d s t o n e s , suggests a r a p i d change i n s e d i m e n t a t i o n s t y l e . The h i g h m i n e r a l o g i c a l and t e x t u r a l m a t u r i t y of t h e sand-stones s u g g e s t s s e v e r a l p r e v i o u s c y c l e s of e r o s i o n and depo-s i t i o n , d e t r i t a l g r a i n s p r o b a b l y d e r i v e d from a mature e a s t -ern s o u r c e . D e p o s i t i o n may have o c c u r e d as bar d e p o s i t s or f i n e d e l t a i c sands as e x t e n s i o n s of t h e E l l e r s l i e a l l u v i a l complex documented by Conybeare (1976) south of Edmonton. From samples c o l l e c t e d i n the study a r e a , the E l l e r s l i e i s suggested t o be Barremian i n age. 5.4. CALCAREOUS MEMBER 5.4.1 . L i t h o l o g y The C a l c a r e o u s Member i s c h a r a c t e r i z e d by i n t e r b e d d e d f i n e g r a i n e d s a n d s t o n e s , s i l t s t o n e s , dark s h a l e s and m a r l s . Nine f a c i e s were r e c o g n i z e d and are summarized i n T a b l e I I I . Sandstones of the C a l c a r e o u s Member are p o r o u s , w e l l s o r t e d , f i n e t o medium g r a i n e d q u a r t z a r e n i t e s , p a r t i a l l y cemented by s i l i c a , c a l c i t e , and c l a y , w i t h c o a l d e t r i t u s i n the m a t r i x , and fo r m i n g t h i n l e n s e s . Framework g r a i n s of q u a r t z , w i t h minor amounts of c h e r t , a r e subangular t o angu-l a r , e x h i b i t i n g t a n g e n t i a l , p o i n t , and l o n g i t u d i n a l c o n t a c t s , or f l o a t i n g i n m a t r i x c l a y s and cement. Hydrocarbon s t a i n i n g i s common. The sandstones e x h i b i t low an g l e c r o s s b e dding, and r i p p l e c r o s s l a m i n a t i o n , and may be e x t e n s i v e l y b i o t u r -1 02 T a b l e II - SUMMARY OF CALCAREOUS ZONE FACIES FACIES DESCRIPTION ENVIRONMENT Sands tone, Q u a r t z A r e n i t e B u f f c o l o u r , beds 0 . 4 to 2 . 0 metres t h i c k , massive, low l e v e l s of b i o t u r b a t i on, and r i p p l e l a m i n a t i o n . Low to moderate c u r r e n t v e l o c i t i e s w i t h medium s c a l e bedforms, such as beaches, p o i n t b a r s , and d i s t r i b u t a r y mouth b a r s Q u a r t z S i 1 t s t o n e Dark g r e y o r b u f f , m assive o r b i o t -u r b a t e d , w i t h escape burrows. Low energy environment, sha 1 1ow waters. Rooted Q u a r t z S i 1 t s t o n e Grey, r o o t e d s i l t w i t h abundent p l a n t d e b r i s , u s u a l l y capped by c o a 1 , o r s c o u r e d s a n d s t o n e . Low t o moderate energy environments which were l a t e r v e g e t a t e d such as upper t i d a l f l a t s , upper p o i n t b a r s , and f l o o d p l a l n s . I n t e r b e d d e d S i 1 t s tones and S h a l e s Wavy Bedded, c r o s s bedded, b i o t u r b a t e d , l e n t i c u l a r bedded, or 1oaded, w i t h o c c a s i o n a l s h e l l debr i s. R e l a t i v e l y low energy environment w i t h a m i x t u r e of s i l t and mud. S h a l e B l a c k and Ma s s i v e w i t h o c c a s i o n a l cabonaceous d e b r i s , o f t e n a c c e s s o r y p y r i t e . Low energy r e d u c i n g environment, p o s s i b l y l ake bottom, lagoon, or 1 n t e r d 1 s t r 1 b u t a r y bay. S h a l e w i t h or i e n t e d she 1 1 debr i s B l a c k l a m i n a t e d s h a l e w i t h zones of she l i s , b u r r o w i n g absent Areas s u b j e c t to p e r i o d i c l i g h t r e w o r k i n g and i n t r o d u c t i o n of s h e l l d e b r i s by storms or o t h e r h i g h e r energy e v e n t s . S h a l e Rubble C l a y r i c h , brown-grey to b l a c k s h a l e , broken i n t o poker c h i p p i e c e s . Low energy environment Coal T h i n , a r g i l l a c e o u s c o a l bands V e g e t a t e d a r e a s , such swamps and f l a t s . A r g i 1 1 a c e o u s L i mestone Tan to g r e y mar 1, o c c a s i o n a 1 1 y g r a d e d or b i o t -u r b a t e d , l a m i n a t e d or e x h i b i t n g s c o u r i n g f e a t u r e s . Beds a r e l a t e r a l l y e x t e n s i ve. Q u i e t and moderate energy a r e a of f i n e c a r b o n a t e d e p o s i t i o n , such as c a r b o n a t e m u d f l a t s lagoons and l a k e benches. T a b l e I I I . D e f i n i t i o n o f l i t h o f a c i e s i n t h e C a l c a r e o u s Zone. 1 03 bated (Plate 11). Two s i l t s t o n e units can be defined: massive or biotur-bated, dark grey to buff s i l t s t o n e , occasionally cemented by c a l c i t e , and a buff grey s i l t s t o n e hosting abundant phytoc-lasts and exhibiting root structures. The l a t t e r s i l t s t o n e s are often capped by thin vitreous coal seams. Interbedded s i l t s t o n e s and shales are common. Wavy bedded units, horizontally bedded, low angle crossbedded, and bioturbated units are common. Lenticular bedding is present but rare. Intensity of bioturbation varies from weak, with well defined v e r t i c a l burrows, to intense, erasing a l l traces of primary depositional structures. Convoluted and slumped units are also recognized. Carbonaceous debris and impres-sions are common. Beds of homogeneous black shale, with rare carbonaceous debris, are common. Thin horizons of very dark brown shale with concentrated lag deposits of mollusc debris oriented p a r a l l e l to bedding, and black shales with disseminated shells were also recognized. Pyrite and ironstone bands at-taining thicknesses up to 2 cm are common. Thin vitreous coal laminations were noted in the carbonaceous shales. Beds of tan to grey brown argillaceous, cryptocrystal-l i n e limestone 0.2 to 10.0 metres thick, lacking well defined r e l i c t b i o l o g i c a l textures, are abundant in the Calcareous Member. Primary sedimentary structures such as scouring and graded bedding suggest deposition as d e t r i t a l carbonate, com-bined with possible inorganic p r e c i p i t a t i o n and sedimenta-1 04 P l a t e 11. C a l c a r e o u s Member sediments. A. Tan a r g i l l a c e o u s l i m e s t o n e of the C a l c a r e o u s Zone, w i t h a s c o u r e d s u r f a c e and h o r i z o n t a l b e d d i n g , (10-29-30-21 W4, 1392.3 m e t r e s ) . B. B i o t u r b a t e d and i n t e r b e d d e d dark s h a l e and l i g h t , f i n e g r a i n e d sandstone of the C a l c a r e o u s Zone, (10-29-30-21 W4, 1392.3 m e t r e s ) . C. Ph o t o m i c r o g r a p h of the C a l c a r e o u s Zone q u a r t z o s e sandstone, cemented by c a l c i t e ( s t a i n e d r e d i n t h i n s e c t i o n ) , ( p o l a r i z e d l i g h t , x64, 6-24-30-22 W4, 1409.3 m e t r e s ) . 105 t i o n . Some c a r b o n a t e may have been c o n t r i b u t e d by b i o g e n i c s o u r c e s . T h i s w i l l be examined f u r t h e r i n development of the d e p o s i t i o n a l model. O s t r a c o d s , p e l e c y p o d s , and g a s t r o p o d s have been r e c o g -n i z e d i n c o r e samples. Chara, C y t h e r e i s , Gomphythere, f i s h and p e l e c y p o d fragments, as w e l l as abundant p l a n t d e b r i s , have been r e c o v e r e d . F a u n a l d i v e r s i t y i s low. K a o l i n i t e and i l l i t e a r e the dominant c l a y s i n s h a l e s of the C a l c a r e o u s Member. C a l c i t e and f e r r o a n d o l o m i t e were a l s o d e t e c t e d . The v e r t i c a l d i s t r i b u t i o n of f a c i e s i s p r e s e n t e d i n se-l e c t e d samples from c o r e d e s c r i p t i o n s ( F i g u r e 3 5). The b a s a l c o n t a c t i s g e n e r a l l y sharp - a b l a c k s h a l e o v e r l i e s sand, s i l t , or b r e c c i a of e a r l i e r C r e t a c e o u s u n i t s . The upper con-t a c t i s u s u a l l y g r a d a t i o n a l and was p i c k e d on l o g s a t the t o p of a s i l t y s h a l e u n i t o v e r l y i n g the uppermost l i m e s t o n e bed. The C a l c a r e o u s Member i s c h a r a c t e r i z e d by c y c l i c d e p o s i t i o n , one c y c l e c o n s i s t i n g of a s h a l e base, o c c a s i o n a l l y c o n t a i n i n g s h e l l d e b r i s , g r a d i n g i n t o a r g i l l a c e o u s l i m e s t o n e , f o l l o w e d by b i o t u r b a t e d s h a l e and s i l t s t o n e w i t h carbonaceous d e b r i s , and capped by f i n e g r a i n e d s a n d s t o n e . The sandstones a r e u s u a l l y o v e r l a i n s h a r p l y by b l a c k s h a l e s or tan l i m e s t o n e s . The r e v e r s e c y c l e was noted i n s e v e r a l c o r e s . The complete c y c l e may not always be p r e s e n t . An upward decrease i n a r g i l -l a c e o u s c o n t e n t of i n d i v i d u a l l i m e s t o n e h o r i z o n s i s noted on gamma ray l o g s . Hydrocarbon s t a i n e d q u a r t z a r e n i t e s a r e common where C a l c a r e o u s Member sediments o v e r l y D r u m h e l l e r 7-2-27-21W4 Gamma Ray D E P T H (metres) ! 1 5 0 0 1 5 1 0 - r r ^ -1 5 3 0 1 520-h^r-p -ir 7-19-30-22W4 Gamma Ray D E P T H ( m e t r e $ 1 5 6 0 1570f 1 5 8 0 D E P T H (metres) 1 3 2 0 13301 10-13-28-19W4 Gamma Rayj 6-15-27-23W4 0..-. 7 ~5 .Drumhel ler ss D E P T H (metres) 1 6 5 0 ^ 1 6 6 0 1 6 7 0 igure 3 5 . V e r t i c a l d i s t r i b u t i o n of l i t h o f a c i e s in the Calcareous Member 1 07 sandstones and s i l t s t o n e s . 5.4.3. Geophysical Log Response The log signature of the Calcareous Member i s d i s t i n c t . The base of the unit i s marked by a sharp break from shales to the underlying Drumheller or E l l e r s l i e Sandstone, or Mississippian limestone. D i f f i c u l t y can arise in unambiguous-ly picking the base where Devi l l e mudstones or calcareous E l l e r s l i e shales underlie Calcareous Member shales. The top of the unit i s marked by a thin shale horizon overlying the f i r s t limestone kick on the geophysical wireline logs. The shale or limestone may be absent where Glauconitic Member sandstones scour into underlying s t r a t a . Examples of t y p i c a l gamma ray, sonic, and e l e c t r i c log signatures are presented in Figure 36. The spontaneous poten-t i a l r e f l e c t s the low porosity exhibited by shales and the gamma ray logs the rapid interbedding of limestones with ra-dioactive shales. A general coarsening upward of units i s noted on the gamma ray p r o f i l e s . The conductivity log as well as the sonic log, exhibits cycle skipping, r e f l e c t i n g the interbedded nature of the unit. In the northwest sector of the map, the Calcareous Member i s s i g n i f i c a n t l y thicker and can be subdivided on geo-physical well logs into upper and lower units, based on a higher content of coarser c l a s t i c material and c y c l i c i t y in the lower unit. The subdivision i s made at the top of a c a l -careous s i l t horizon. Only the upper finer unit i s recognized 108 A. 6-15-27-20W4 B. 6-30-29-23W4 Figure 36. C h a r a c t e r i s t i c log signatures of the Calcareous Member. In A, Calcareous Member sediments overly Drumheller Sandstones, in B they rest d i r e c t l y on Miss i s s i p p i a n limestone. 109 above the Drumheller sandstones elsewhere in the map area. 5.4.2. Di s t r i b u t i o n and Thickness The Calcareous Member has been recognized over much of the Alberta Plains. The zone extends throughout the entire study area, ranging in thickness from 0 to 43 metres, with the greatest thickness in the northwest sector of the map where deposits of the Drumheller unit are absent. The thick-est deposits, trending northwest-southeast, are found s l i g h t -ly west of the zero isopach contour of the Drumheller Sandstone. Where Drumheller sandstones are absent and Calcareous Member fines rest d i r e c t l y upon Mississippian or Dev i l l e s t r a t a , the Calcareous Member sediments vary greatly in thickness, and appear to relate to topography defined by the pre-Cretaceous unconformity. The pa l e o r e l i e f of the pre-Cretaceous surface exerts some control on d i s t r i b u t i o n and thickness of the Calcareous Member. In the northwest sector of the study area, paleohighs inferred from the Mannville isopach and Mississippian maps correlate with thin accumula-tions of the Calcareous Member. Not a l l thins correlate with paleohighs, some are related to channeling by overlying f l u -v i a l sands. Where the Drumheller sandstones are present, Calcareous Member sediments are thinner, exhibit less v a r i a -b i l i t y in thickness, and gradually thin towards the east. Correlation with topography of the pre-Cretaceous surface i s more subtle. Greatest thicknesses of the unit in the eastern sector of the study area appear over greatest accumulation of 1 10 B a s a l Q uartz sand, d e f i n i n g major a l l u v i a l c h a n n e l s i t e s . The s t r o n g c o r r e l a t i o n between d i s t r i b u t i o n of the a l l u v i a l sands and the f i n e g r a i n e d C a l c a r e o u s Member su g g e s t s a g e n e t i c r e l a t i o n s h i p between the two u n i t s . In F i g u r e 37, a c a r t o o n s i m p l i f i e d from c r o s s - s e c t i o n 9 (Appendix I X ) , the u n i t i s t h i c k e s t i n the n o r t h e a s t w i t h s e v e r a l l a t e r a l l y c o n t i n o u s l i m e s t o n e h o r i z o n s . M a r l beds a r e more numerous where the zone i s t h i c k e s t . The l i m e s t o n e s can be c o r r e l a t e d over s e v e r a l k i -l o m e t r e s , i n d i c a t i n g a s t a b l e d e p o s i t i o n a l system. The l i m e -s t o n e s a r e observed t o s p l i t , as i n f i g u r e 37, s u g g e s t i n g a sudden deepening or e x t e n s i o n of the d e p o s i t i o n a l b a s i n . 5.4.4. D e p o s i t i o n of the C a l c a r e o u s member P a l e o n t o l o g i c and p a l y n o l o g i c a l d a t a suggest t h a t s e d i -ments of the C a l c a r e o u s Member were d e p o s i t e d i n f r e s h t o b r a c k i s h w a t e r s , p o s s i b l y most b r a c k i s h i n s t r a t i g r a p h i c a l l y youngest beds. The abundance of c o a l d e b r i s , l a c k of t h i c k , massive s h a l e beds, abundance of i n t e r b e d d e d s i l t s t o n e and s h a l e , and e x t e n s i v e b i o t u r b a t i o n of many beds suggest depo-s i t i o n of sediment i n f a i r l y s h a l l o w w a t e r s . Beds of dark brown s h a l e , l i t t e r e d w i t h unbroken m o l l u s c v a l v e s , would have been d e p o s i t e d i n s h a l l o w oxygenated w a t e r s , assuming the s h e l l s a re authochthonous i n o r i g i n . Dark s h a l e s w i t h bands of broken s h e l l d e b r i s suggest t r a n s p o r t of d e b r i s from a d j a c e n t p o p u l a t e d a r e a s , p o s s i b l y i n t u r b i d i t y c u r r e n t s , or as l a g d e p o s i t s of mud f i l l e d c h a n n e l s . The f i n e g r a i n s i z e 0 1 2 » ' i km. F i g u r e 37. D i s t r i b u t i o n of the C a l c a r e o u s Member, C r o s s -S e c t i o n 9. L a t e r a l l y e x t e n s i v e l i m e s t o n e s are e n v e l o p e d i n s i l t s t o n e s and s h a l e s . 1 12 of the sediment and preservation of lower regime structures indicate that the environment of deposition was of moderate to low energy with some changes in current v e l o c i t y and d i -rection indicated in upper beds by wavy and l e n t i c u l a r bed-ding. Sandstones of the Calcareous Member are fine grained, t e x t u r a l l y submature, quartzose sands with f a i r porosity, or cemented by c a l c i t e . The sands form small lensoid bodies en-veloped by shales and s i l t s , with gradational basal and sharp upper contacts. They are interpreted as small deltas or sand bars, the sediment derived from reworking of E l l e r s l i e and Drumheller a l l u v i a l sandstones. Thin l a t e r a l l y extensive limestone beds are common. Carbonate deposition in fresh to brackish waters may occur in four ways: (1) derived from erosion and transported; or de-posited by (2) b i o c l a s t i c processes; (3) inorganic p r e c i p i t a -t i o n ; and (4) diagenetic processes (Kelts and Hsu, 1978). D e t r i t a l carbonate, usually as s i l t or clay size p a r t i c l e s , may be carried by rivers and deposited from suspension as widespread pelagic sediment derived from carbonate te r r a i n s . B i o c l a s t i c sedimentation of carbonate in lakes i s presently ar product of photosynthesis mainly by the rare green alga Phacotus (Kelts and Hsu, 1978). Charophytes, chlorophytes and other benthic, l i t t o r a l or free f l o a t i n g macrophyte f l o r a u t i l i z e carbon largely in the form of bicarbonate ions during photosynthesis. Bicarbonate use produces a microenvironment of higher pH immediately surrounding the hydrophyte, which in 1 1 3 turn induces p r e c i p i t a t i o n of calcium carbonate and encrusta-tion (Wetzel, 1960, c i t e d in Kelts and Hsu, 1978). Other bio-c l a s t i c sources of carbonate are calcareous skeletons of fauna such as ostracods. Inorganic p r e c i p i t a t i o n of carbonate r e f l e c t s supersaturation of the lake waters, due to physical and biochemical changes usually related to seasonal tempera-ture e f f e c t s on the s o l u b i l i t y of carbon dioxide and to a s s i -mulation of carbon dioxide during photosynthetic a c t i v i t y . Diagenetic processes contribute a minor percentage of car-bonate by r e c r y s t a l l i z a t i o n and cementation (Kelts and Hsu, 1978). Limestones of the Calcareous Member were probably derived from a combination of processes. They may have been deposited as pelagic sediments transported- as d e t r i t a l clay and s i l t sized grains in r i v e r s , formed as encrustations on charophytes, as shown by embedded f l o r a in the limestones, and probably also inorganically precipitated in response to climatic fluctuations and photosynthesis. Murphy and Wilkinson (1980) recognized thick deposits of marl forming shallow f l a t topped benches, around the perime-ter of Lake L i t t l e f i e l d , Michigan. Benches are d i v i s a b l e into two units, a landward platform inclined at a low angle, cov-ered by blue green a l g a l p i s o l i t h s and carbonate sand in very shallow waters, and a steep bench slope, covered with a thick growth of Chara which becomes encrusted with carbonate in the summer. The platform is exposed and colonized as the bench progrades. A d i s t i n c t v e r t i c a l succession of facies was re-1 14 c o g n i z e d : o s t r a c o d m i c r i t e a t the base, f o l l o w e d by g a s t r o p o d m i c r i t e , a zone of sandy a l g a l m i c r i t e , p i s o l i t i c g r a v e l , and a cap of c a l c a r e o u s peat ( F i g u r e 3 8 ) . T h i s s t y l e of s h a l l o w water c a r b o n a t e s e d i m e n t a t i o n c o u l d be p a r t i a l l y r e s p o n s i b l e f o r the f a c i e s observed i n the C a l c a r e o u s Member. D i s t r i b u t i o n of the C a l c a r e o u s and D r u m h e l l e r Members, and f a c i e s changes r e c o g n i z e d w i t h i n the b a s a l a l l u v i a l sand-s t o n e s , suggest d e p o s i t i o n of the two u n i t s i n p a r t , contem-p o r a n e o u s l y . G r e a t e s t a c c u m u l a t i o n of the C a l c a r e o u s Member i s i n a n o r t h w e s t - s o u t h e a s t t r e n d i n g zone i n the northwest s e c t i o n of the study a r e a where D r u m h e l l e r sandstones a r e abs e n t . T h i s can be i n t e r p r e t e d as the i n i t i a l s i t e of a s h a l l o w , f r e s h water l a k e i n which f i n e muds, s i l t s , and c a r -bonaceous muds accumulated. The t r e n d of the p a l e o l a k e p a r a l -l e l s the subcrop p a t t e r n of M i s s i s s i p p i a n f o r m a t i o n s perhaps r e f l e c t i n g the l o c a t i o n of a n o n - r e s i s t i v e P a l e o z o i c bed. C l o s u r e of the l a k e may be due t o damning of the e l o n g a t e p a l e o l o w by E a r l y C r e t a c e o u s a l l u v i a l f a n d e p o s i t s . The c y c -l i c a l d e p o s i t i o n of sediment noted i n p a r t of the C a l c a r e o u s member can be i n t e r p r e t e d as a response t o s u b t l e t e c t o n i c and c l i m a t i c changes i n a c l o s e d l a c u s t r i n e b a s i n . The p r e -sence of one l a r g e body of water i s suggested by the l a t e r a l c o n t i n u i t y of l i m e s t o n e beds. In the e a s t e r n h a l f of the study a r e a , C a l c a r e o u s Member f i n e s cap s i l t s t o n e s and sand-s t o n e s of the D r u m h e l l e r Member and E l l e r s l i e F o r m a t i o n . T h i c k e s t d e p o s i t s a re i n p a l e o v a l l e y s . T h i s d i s t r i b u t i o n can be accounted f o r by drowning of the E a r l y C r e t a c e o u s a l l u v i a l 1 15 massive black shale ostracodal micrite gastropoda! micrite sandy algal micrite pisolitic gravel.scour silts and shales coaly siltstone sandstone bay muds gure 38. Formation of marl deposits in Lake L i t t l e f i e l d , Michigan (Murphy and Wilkinson, 1980). 1 1 6 sand complex and f o r m a t i o n of a l a r g e embayment or l a k e i n the study a r e a . No marine sediments were r e c o g n i z e d . In the l a t e A p t i a n - e a r l y A l b i a n , southward t r a n s g r e s s i o n of the C l e a r w a t e r Sea l e d t o drowning of former c h a n n e l s and the i n v a s i o n of marine waters i n t o c e n t r a l and s o u t h e r n A l b e r t a (McLean, 1981; W i l l i a m s , 1963; G l a i s t e r , 1959). W i l l i a m s (1963) i d e n t i f i e d marine f o r a m i n i f e r a i n a w e l l n orthwest of Edmonton. M e l l o n and W a l l (1961) noted i n t e r f i n -g e r i n g of b r a c k i s h t o marine f a u n a l assemblages i n the sub-s u r f a c e of the s o u t h - c e n t r a l p l a i n s ( c i t e d i n McLean, 1981). The s o u t h e r n e x t e n t of the marine t r a n s g r e s s i o n i s s t i l l a q u e s t i o n of debate and of importance i n i n t e r p r e t i n g the de-p o s i t i o n a l environment of the C a l c a r e o u s Member. R e g i o n a l paleogeography as r e c o n s t r u c t e d by McLean (1981) f o r the Lower A l b i a n , s u g g e s t s non-marine c o n d i t i o n s t o t h e e a s t , west and s o u t h of the study a r e a ( F i g u r e 4 ) . A major r i v e r system, the Edmonton c h a n n e l , d r a i n s from the s o u t h , i n t o an embayment a t the s o u t h e r n e x t e n s i o n of the Moosebar-C l e a r w a t e r Sea. W i t h t h i s i s mind i t seems r e a s o n a b l e w i t h i n the study a r e a t h a t C a l c a r e o u s Member sediments were i n i t i a l l y d e p o s i t -ed i n a f r e s h water l a c u s t r i n e environment, contemporaneous w i t h the D r u m h e l l e r s a n d s t o n e s . W i t h t r a n s g r e s s i o n of the sea, drowning of r i v e r v a l l e y s , f o r m i n g e s t u a r i e s , would o c c u r . In the study a r e a , uppermost C a l c a r e o u s Member s e d i -ments compare f a v o u r a b l y w i t h the modern Chesapeake Bay e s -t u a r y on the American A t l a n t i c c o a s t l i n e . In the upper 1 1 7 reaches of the e s t u a r y , mean water depth i s 4.8 m ( S c h u b e l , 1971) . Bottom sediments a r e composed of s i l t and c l a y w i t h abundant o r g a n i c d e b r i s . C o a r s e r sediment i s found i n the l i t t o r a l zone. Water s a l i n i t i e s a r e v a r i a b l e , from f r e s h t o b r a c k i s h , r e f l e c t i n g v a r i a b l e volumes of f r e s h water d i s -charge from the Susquehanna R i v e r . In the James R i v e r e s -t u a r y , V i r g i n i a , s i l t y c l a y i s d e p o s i t e d i n the r i v e r and upper e s t u a r y , c l a y e y sand and sandy s i l t p r edominates i n the mid d l e e s t u a r y , and sand o c c u r s near the mouth ( N i c h o l s , 1972) . The C a l c a r e o u s Member sediments i n the D r u m h e l l e r a r e a are i n t e r p r e t e d as r e c o r d i n g the t r a n s i t i o n from a f l u v i a l -l a c u s t r i n e environment t o a s h a l l o w water e s t u a r i n e s e t t i n g . 1 18 VI. UPPER MANNVILLE GROUP SEDIMENTS 6.1. GLAUCONITIC SANDSTONE MEMBER The Glauconitic Sandstone Member of the Upper Mannville Group was i n i t i a l l y recognized by Workman (1963) as an exten-sive mappable unit within the subsurface of Alberta. Regionally, the lithology of the member changes from fine quartzose sandstones in the southwest to fine to coarse, s a l t and pepper quartz and chert sandstones in the west and north-west of Alberta. G l a i s t e r (1959) relates t h i s change to de-pos i t i o n a l environment and provenance. The member i s pre-dominantly marine in the Edmonton area, characterized by green glauconitic sands, but becomes non-marine towards the south, eventually loses i t s l i t h o l o g i c uniqueness, and i s incorporated into the basal a l l u v i a l sands. The l o c a l character of the Glauconitic Member was exam-ined in the study area, and the relationship of t h i s unit to Lower Mannville sediments investigated. A preliminary en-vironmental interpretation of the unit was attempted. 6.1.1. Lithology The Glauconitic Sandstone i s conventionally defined as the f i r s t major sandstone above the Calcareous Member lime-stones (Glaister (1959); Lexicon (1969)). Within the study area, two l i t h o l o g i c a l l y d i s t i n c t sands are recognized in 1 19 th i s position: (1) buff, fine to medium grained, quartz arenites and sublitharenites, and (2) grey, s a l t and pepper, fine to medium grained l i t h a r e n i t e s and feldspathic l i -tharenites. The l a t t e r sands are more abundant. Thick accumu-lation s of quartzose sandstone are characterized by preserva-tion of a regular v e r t i c a l sequence. Basal contacts are ero-si o n a l , occasionally hosting r i p up c l a s t s of underlying strata or lag deposits of coaly debris, and are followed by low angle crossbedded units, overlain by planar bedded, and massive units. Flaser and l e n t i c u l a r bedding, and burrowed sediment, i s common in the uppermost beds. Rooted s i l t s , car-bonaceous shales, and coals cap uniform and f i n i n g upward sequences. Petrographically t h i s sandstone i s a submature to mature quartz arenite to sublitharenite, with fine angular to subangular framework grains of quartz, rare black chert, and a r g i l l i t e . Accessory d e t r i t a l muscovite i s common. The sands are f r i a b l e or p a r t i a l l y cemented by c a l c i t e and syntaxial overgrowths of quartz. Matrix i s minor (0 to 10 percent), and consists of s i l t size quartz, phytoclasts, and clay. Pressure solution i s absent to moderate. The sandstone i s porous, averaging 20% porosity, and is l o c a l l y hydrocarbon bearing. The l i t h i c sands exhibit erosional or gradational con-tacts with underlying s t r a t a . Sedimentary structures are h i -ghlighted by dark shale laminae and carbonaceous debris. Zones with abundant mud and ironstone concretionss are common (Plates 12 and 13). Clasts are p r e f e r e n t i a l l y oriented paral-l e l to bedding and exhibit p a r a l l e l lamination, low angle 120 11-21-30-22W4 Spontaneous Potential Gamma Ray Plate 12. Core photographs of Upper Mannville sandstones. A. Large ironstone nodule deforming o r i g i n a l bedding structure, (11-21-30-22 W4, 1416.7 metres). B. Shale pebbles, rounded to angular, in a sandstone matrix, showing a preferred orientation p a r a l l e l to bedding and traces of o r i g i n a l primary sedimentary structures, i n d i c a t i v e of a depositional environment of moderate to high current v e l o c i t y , (11-21-30-22 W4, 1420.3 metres). 121 P l a t e 13. A d d i t i o n a l c o r e photographs of Upper M a n n v i l l e sandstone. A. I n t e r b e d d e d sandstone and s h a l e , i n r o u g h l y e q u a l amounts, w i t h s m a l l s c a l e c r o s s b e d d i n g a t the base, (11-21-20-22 W4, 1428.7 m e t r e s ) . B. S m a l l s c a l e c r o s s bedded sandstone, l a c k i n g b u r r o w i n g , s u g g e s t i v e of a sandy environment w i t h low t o moderate v e l o c i t y c u r r e n t s , (11-21-30-22 W4, 1424.6 m e t r e s ) . C. Photomicrograph of the Upper M a n n v i l l e l i t h i c s andstone, ( c r o s s e d p o l a r i z e r s , x64, 10-23-27-20 W4, 1333.1 m e t r e s ) . Red i s c a l c i t e s t a i n e d by A l i z a r i n Red S. 122 c r o s s bedding and s o f t sediment d e f o r m a t i o n . In v e r t i c a l se-quence, these sandstones a r e c h a r a c t e r i z e d by a s c o u r e d base, o v e r l a i n by low a n g l e c r o s s b e d d e d s a n d s t o n e s , f o l l o w e d by a l t e r n a t i n g zones of massive sandstone and c l a s t - r i c h zones. P a r a l l e l bedded sandstones may top massive u n i t s . The se-quence f i n e s upward from medium or f i n e , t o v e r y f i n e g r a i n e d s a n d s t o n e s . C o n v o l u t e d and b i o t u r b a t e d beds commonly cap the sequence. These s a l t and pepper sands a r e immature t o subma-t u r e , w i t h v a r i a b l e p e r c e n t a g e s of p l a g i o c l a s e and m i c r o -c l i n e , dark c h e r t , v o l c a n i c , metamorphic, and s e d i m e n t a r y rock fragments, d e t r i t a l m u s c o v i t e , and a n g u l a r q u a r t z ( P l a t e 13). M a t r i x i s minor t o abundant. C a l c i t e , d o l o m i t e , and s i -d e r i t e cements a r e p r e s e n t . S i d e r i t e i s most common i n the f i n e r g r a i n e d f a c i e s . Framework g r a i n s a r e a n g u l a r t o su-brounded, w i t h t a n g e n t i a l and l o n g c o n t a c t s common. The sands are w e l l i n d u r a t e d and l a c k the good p o r o s i t y found i n the q u a r t z a r e n i t e s . X-ray d i f f r a c t i o n a n a l y s i s of the sandstone m a t r i x r e v e a l e d w h i t e mica ( i l l i t e ) , w i t h a c c e s s o r y kao-l i n i t e , c a l c i t e , q u a r t z , and f e l d s p a r i n the m a t r i x f i n e s . G l a u c o n i t e was not r e c o g n i z e d i n e i t h e r sand. I t i s thus recommended t h a t the term G l a u c o n i t i c Sandstone not be ap-p l i e d t o t h e s e sandstones of the D r u m h e l l e r a r e a , and be r e -s t r i c t e d t o the green marine sands n o r t h and west of the study a r e a . For t h i s r e p o r t and f u t u r e r e f e r e n c e the names Carbon Sandstone Member and Three H i l l s sandstone a r e a p p l i e d t o the q u a r t z o s e and l i t h i c sandstones r e s p e c t i v e l y . The l a t t e r has not been g i v e n a f o r m a l name due t o u n c e r t a i n t y i n 123 l a t e r a l and v e r t i c a l extent and the lack of a f u l l y cored interval to set as a type location from t h i s study. The type location for the Carbon Sandstone Member is selected as the Shell Carbon 37-17 Well (7-17-29-22 W4) , between 1380.1 and 1389.3 metres. At thi s l o c a l i t y fine grained quartzose sand-stones f i l l a scour carved into Calcareous Member sediments, and are overlain by coaly, l i t h i c sandstones of the Grand Rapids Formation. The member is 9.2 metres thick. The Three H i l l s sandstone has been cored in part at BA et a l . Ghost Pine 11-21-30-22 W4. Associated with both sandstones are structureless, rooted and bioturbated interbedded shales and s i l t s t o n e s , with l e n t i c u l a r and wavy bedding disrupted by burrowing, and grey to black, massive or bioturbated shales. Pyrite i s a common accessory in the shales. The units are l o c a l l y c a l -careous. 6.1.2. Geophysical Log Response Geophysical well logs r e f l e c t the sandy and s i l t y nature of the unit. Typical log signatures are presented in Figure 39 and Plate 12. Blocky or b e l l shaped spontaneous potential and gamma p r o f i l e s are c h a r a c t e r i s t i c of the Carbon Sandstones. Three H i l l s sandstones exhibit upward f i n i n g , upward coarsening, and serrated log p r o f i l e s . The abundance of shale c l a s t s in the unit may be responsible for the varie-ty of log signatures. An upward coarsening sequence suggested by gamma ray logs may be due to shale c l a s t s at the base of D E P T H ( m e t r e s ) 1550H 1560 1570 1580 10-19-29-22W4 Spontaneous Potential Gamma Ray 6-6-28-22W4 DEPTH (m e t re s ) 1590-^ 1600 1610 1620i Spontaneous Pofential Gamma Ray F i g u r e 39. G e o p h y s i c a l and l i t h o l o g i c l o g p r o f i l e s of the Carbon Sandstone. 125 the sandstone. F l u c t u a t i n g gamma ray and spontaneous p o t e n -t i a l l o g responses may be due t o i n t e r b e d d i n g of sand and s h a l e , or c o n c e n t r a t i o n s of s h a l e c l a s t s i n s e l e c t e d h o r i z o n s w i t h i n a sand. T h i s may r e s u l t i n a low e s t i m a t i o n of sand-stone t h i c k n e s s and e r r o r s i n i n t e r p r e t a t i o n of s t r a t i g r a p h y . 6.1.3. D i s t r i b u t i o n and T h i c k n e s s The G l a u c o n i t i c Sandstone e q u i v a l e n t i s c h a r a c t e r i z e d by h e t e r o g e n e i t y i n t h i c k n e s s and d i s t r i b u t i o n . Carbon q u a r t z o s e s andstones a re found as northwest t r e n d i n g l e n s e s a v e r a g i n g 10 km l o n g , 5 km wide, and up t o 15m t h i c k . The l e n s e s have concave bases w i t h r e l a t i v e l y f l a t t o p s , o f t e n f i l l i n g s c o u r s c u t i n t o Lower M a n n v i l l e s e d i m e n t s . As i l l u s t r a t e d i n F i g u r e 40, the Carbon sands a t t a i n maximum d e p o s i t i o n a l t h i c k n e s s e s where f i l l e d s c o u r s c u t i n t o u n d e r l y i n g s t r a t a . The sandstone b o d i e s a r e found on both p a l e o h i g h s and p a l e o l o w s d e f i n e d by the Lower M a n n v i l l e i s o p a c h , s u g g e s t i n g m i n i m a l i n f l u e n c e by the t o p o g r a p h i c e x p r e s s i o n of the p r e - C r e t a c e o u s u n c o n f o r m i t y (see s e c t i o n 1, Appendix I X ) . In many w e l l s the q u a r t z o s e s andstones a r e a b s e n t . The l i t h i c s andstones form t h i n l e n s e s , up t o 6 metres t h i c k . P r e l i m i n a r y i n v e s t i g a t i o n sug-g e s t s t h a t these sandstones form l a t e r a l l y e x t e n s i v e u n i t s . SW NE M I S S I S S I P P I A N F i g u r e 4 0 . D i s t r i b u t i o n o f t h e C a r b o n S a n d s t o n e , c r o s s -s e c t i o n 2. T h e q u a r t z o s e s a n d s t o n e s f i l l a s c o u r c u t i n t o u n d e r l y i n g C a l c a r e o u s M e m b e r f i n e s . CTi 1 27 6.1.4. Deposition of the Glauconitic Member Many depositional environments have been l o c a l l y recog-nized within the Glauconitic Member: beaches, barrier bars, a l l u v i a l channels, and t i d a l sequences (Holmes and Riward, 1976; Conybeare, 1976). The sediments are underlain by fresh to brackish water deposits of the Calcareous Member and over-l a i n by interbedded sandstones and coals interpreted as coas-t a l marsh deposits (Glaister, 1959). The absence of glauconite and other marine indicators, abundance of coaly debris, and results from paleontological analysis of shale samples, suggest deposition of the Carbon and Three H i l l s sandstones took place in a non-marine to t r a n s i t i o n a l environment, south of the maximum Albian-Aptian marine advance. Equivalent sandstones toward the north, northeast, and northwest contain glauconite. The Carbon sandstones appear to have been deposited by channel processes. Such thick, f i n i n g upward sequences of moderately to poorly sorted, fine to medium grained sand-stone, f i l l i n g scours cut into underlying sediments, could t h e o r e t i c a l l y be produced by deposition of sediment in anas-tomosing r i v e r s , low sinuosity meandering r i v e r s , d i s t r i b u -tary channels, and estuarine channels. The la s t interpreta-tion best f i t s the features of the Carbon sandstone. Geometry of the sandstone lenses, up to 30 m thick, 10 km long, and 5 km wides, exclude deposition in anastomosing r i v e r channels. Sandstones deposited in anastomosing channels accumulate by v e r t i c a l accretion, forming narrow l i n e a r , shoestring sand 1 28 bodies. Sedimentary structures of the point bar sequence are not common in the Carbon sand. One would expect to find ripple cross-lamination in the upper beds, abundant medium scale cross beds throughout the unit, and evidence for con-tinuation of the meander channel to the southeast. Preliminary investigation does not reveal continuation of the sand channels. The Carbon sandstones are bioturbated or flaser bedded at the top of the sequence, suggesting shallow waters and possibly t i d a l processes. The lower beds are cross bedded or massive, with a lag deposit of coarse sand with wood chips. The thin rooted s i l t s t o n e s and coals capping Carbon sandstones can be interpreted to r e f l e c t rapid f i l l i n g of the estuary and emergence of the sand bars as islands. The absence of glauconite can be accounted for by rapid deposi-tion of sediment or high rates of fresh water infl u x , main-taining brackish water conditions. The sedimentary structures, geometry, and petrography of the Carbon sandstone compare favourably with modern estuarine sand deposits. The Haringvliet (Netherlands) i s characterized by the presence of interlaced channels and elongated shoals (Oomkens and Terwindt (1960)). Shoals are usually submerged but may r i s e to mean high water l e v e l . Channels migrate l a t -e r a l l y by eroding one bank and depositing on the other. Based upon a study of the recent inshore sands in the Haringvliet (Netherlands), Oomkens and Terwindt (1960) proposed the f o l -lowing model for estuarine channels. Coarse to medium grained, poor and moderately sorted sandstones are deposited 1 29 at the base of the channel. A lag deposit, consisting of sh e l l s , peat lumps, wood debris, or clay c l a s t s , may be pre-sent. The lowermost beds are characterized by forset cross-bedding. In the upper half of the sequence, horizontal and massive bedded sandstones are present, alternating with thin clay laminea. Burrowed and fl a s e r bedded sandstones commonly cap the sequence. The channels migrate in a l a t e r a l d i r e c -tion, producing elongate sandstone lenses, oriented p a r a l l e l to the t i d a l d i r e c t i o n . In addition to the above characteris-t i c s , Meckell (1975), studying Holocene sand bodies in the Colorado delta area, noted (1) that estuarine channel se-quences are characterized by a s l i g h t f i n i n g upward in grain size; (2) laminea of macerated carbonaceous material can be very common; (3) s h e l l hash i s rare; (4) the dominant sedi-mentary structure i s p a r a l l e l lamination and bedding with some cross bedding at the base; and (5) burrows are common in the muddier sections. Estuarine channels w i l l always have a sharp scoured basal contact with underlying sediments. In the Colorado Delta basin, northern Gulf of C a l i f o r n i a , estuarine channel deposits reach 30 m in thickness, 15 km in length and 7 km in width. Modern estuaries are flanked l a t e r a l l y by t i d a l f l a t s , and merge basinward with marine t i d a l bar complexes and ups-tream with normal f l u v i a l channels (Meckel, 1975). The quart-zose Carbon sandstones are flanked l a t e r a l l y by wavy bedded and bioturbated fine grained sediments, merge basinward into glauconitic sandstones interpreted to be barrier bars 1 30 (Holmes, et a l . , 1976), and upstream lose their l i t h o l o g i c i d e n t i t y , becoming incorperated into the lower Mannville basal a l l u v i a l sands (Glaister, 1959). The development of linear sand ridges, flanked by mud f l a t s and marshes is most abundent under macrotidal condi-tions (Hayes, 1975). River deltas, barrier islands, and t i d a l deltas are best developed in microtidal regions. From the interpretation of environment and facies relationships, i t i s suggested that the t i d a l range in the Drumheller area during deposition of the Carbon sandstone could have been macrotidal (greater than 4 metres), a l o c a l l y high t i d a l range due to the morphology of the coastline as seen today on the coast of western Europe. Stunted barrier islands and abundent t i d a l i n l e t s and deltas occur on the mesotidal shoreline of the Netherlands. The orientation of shoreline sands changes from p a r a l l e l to perpendicular to the coastline in the macrotidal region near the mouths of the Elbe and Weser ri v e r s of west-ern Germany. Where tides are very small on the western coast of northern Denmark, long linear barrier islands have devel-oped (Hayes, 1975). Much of the Three H i l l s sandstone appears to have been deposited by shallow meandering rivers across a coastal bay. The sand sequences exhibit f i n i n g upward in grain size of moderately sorted sandstone, and are characterized by a sharp erosional base. Shale c l a s t s scattered throughout the section and in well defined beds (Plates 12 and 13) are common in point bar sequences. Cross bedded sandstones can be i n t e r -131 p r e t e d as sands d e p o s i t e d by m e g a r i p p l e s on the lower reaches of the p o i n t b a r ; even p a r a l l e l l a m i n a t e d sand, o f t e n marked by o r g a n i c d e b r i s , r e f l e c t i n g d e c r e a s i n g energy, and f i n e r , c r o s s r i p p l e d sands c o m p r i s i n g upper p o i n t bar d e p o s i t s . C l a y i n t e r b e d s i n the uppermost beds, commonly e x h i b i t r o o t mar-k i n g . The absence of s h e l l d e b r i s , l a c k of bimodal c u r r e n t d i r e c t i o n i n d i c a t o r s and absence of r i p p l e d sands a t the base, and f l a s e r and l e n t i c u l a r bedding a t the t o p of the sand sequences ( B a r w i s , 1972), show t h a t these sands were not d e p o s i t e d i n t i d a l c h a n n e l s , which c o u l d produce s i m i l a r f i n i n g upwards d e p o s i t s . G l a i s t e r (1959) and C h r i s t o p h e r (1974) suggest t h a t l i t h i c components i n the Upper M a n n v i l l e sandstones were d e r i v e d from the Canadian C o r d i l l e r a , w i t h encroachment of B l a i r m o r e molasse sediments e a s t w a r d i n t o the A l b e r t a Trough. T h i s would i n f e r e a s t - w e s t t r e n d i n g c h a n n e l systems. Putnam (1982) c o n c l u d e s t h a t a s o u t h e r n - s o u t h w e s t e r n s o u r c e , perhaps the Rocky Mountains of w e s t e r n Montana and Idaho would p r e -sent a more r e a l i s t i c s o u r c e a r e a . T h i s agrees w i t h the p i c -t u r e p r e s e n t e d by E i s b a c h e r e t a l . , (1974) of a n o r t h - s o u t h t r e n d i n g r i v e r system, s u b p a r a l l e l t o the mountain f r o n t , d u r i n g d e p o s i t i o n of the B l a i r m o r e and M a n n v i l l e s t r a t a , and the t r e n d of c h a n n e l s as d e t e r m i n e d i n t h i s s t u d y . D u r i n g d e p o s i t i o n of the Carbon and Three H i l l s sand-s t o n e s i n the D r u m h e l l e r a r e a , i t appears t h a t r e g r e s s i v e c o n d i t i o n s l e a d t o r e - e s t a b l i s h m e n t of a f l u v i a l s e t t i n g 1 32 a f t e r i n c u r s i o n of b r a c k i s h w a t e r s . The q u a r t z o s e Carbon Sandstones were d e r i v e d from an e a s t e r n s o u r c e , d e p o s i t e d as e s t u a r i n e c h a n n e l s . They may have been d e p o s i t e d i n p a r t con-temporaneously w i t h upper C a l c a r e o u s Member se d i m e n t s , be-f o r e , and contemporaneous w i t h the Three H i l l s s a n d s t o n e s . The l i t h i c Three H i l l s s andstones r e f l e c t a s o u t h w e s t e r n source a r e a , i n t e r p r e t e d t o have been d e p o s i t e d i n c h a n n e l s and as overbank sandstones on a r e g r e s s i v e c o a s t a l p l a i n . 1 33 V I I . DEPOSITIONAL MODEL FOR THE LOWER MANNVILLE 7.1. PHYSIOGRAPHY AND TECTONICS E r o s i o n p r e v a i l e d over s e d i m e n t a t i o n from the P e n n s y l v a n i a n t o the C r e t a c e o u s P e r i o d . A broad, low r e l i e f a l l u v i a l p l a i n formed as r i v e r s i n c i s e d c h a n n e l s i n t o the u n d e r l y i n g P a l e o z o i c s t r a t a . The pa l e o t o p o g r a p h y of the p r e -C r e t a c e o u s s u r f a c e as d e f i n e d by the Lower M a n n v i l l e i s o p a c h , r e f l e c t s the l a t e s t of thes e c h a n n e l systems, i n i t i a t e d by Kimmeridgian t o Neocomian u p l i f t of the Precam b r i a n S h i e l d ( C h r i s t o p h e r , 1975). D r a i n a g e was from h i g h e r a r e a s i n the n o r t h e a s t . D u r i n g t h i s e r o s i v e p e r i o d , w e a t h e r i n g of c a r -bonate s t r a t a r e s u l t e d i n a c c u m u l a t i o n of i n s o l u b l e wea-t h e r i n g p r o d u c t s , now p r e s e r v e d as the D e v i l l e F o r m a t i o n , which were d e p o s i t e d ir\ s i t u and as l o c a l d e b r i s f l o w s on a l l u v i a l f a n s . D e v i l l e sediments were d e r i v e d p r o x i m a l t o the d e p o s i t i o n a l s i t e . I n i t i a l w i d e s p r e a d s e d i m e n t a t i o n i s marked by accumula-t i o n of the D r u m h e l l e r a l l u v i a l sands, r e f l e c t i n g stream ag-g r e d a t i o n a s s o c i a t e d w i t h an e u s t a t i c r i s e i n sea l e v e l . The sands were d e p o s i t e d i n sandy, low s i n u o s i t y , b r a i d e d streams, on fa n s and a l l u v i a l p l a i n s , contemporaneous w i t h the D e v i l l e F o r m a t i o n . W i t h i n the study a r e a , d i s t r i b u t i o n and f a c i e s changes of the D r u m h e l l e r sandstone have been i n -t e r p r e t e d as sand sands d e p o s i t e d as an apron of c o a l e s c i n g b r a i d e d stream d e p o s i t s m a r g i n a l t o a f r e s h w a t e r l a k e . S m a l l 1 34 c o a r s e n i n g upward sequences of D r u m h e l l e r sandstone a t the western margin of the sand s h e e t , have been i n t e r p r e t e d as G i l b e r t type d e l t a d e p o s i t s . The s i t e of l a c u s t r i n e d e p o s i -t i o n appears t o have been a p a l e o v a l l e y cut by a p r e v i o u s e r o s i v e e v e n t , w i t h c l o s u r e p o s s i b l y due to damming by a l l u v -i a l fan d e p o s i t s . Two p a r t l y c o r r e l a t i v e sandstone l i t h o l o g i e s were r e c o g -n i z e d i n the D r u m h e l l e r u n i t , a b a s a l a r g i l l a c e o u s t o subma-t u r e c h e r t a r e n i t e , and a younger a r g i l l a c e o u s t o mature q u a r t z a r e n i t e . The b a s a l c h e r t sandstones are 1 i t h o l o g i c a l l y s i m i l a r t o the J u r a - C r e t a c e o u s Success sands of southwest Saskatchewan d e s c r i b e d by C h r i s t o p h e r (1975), and J3 sands of Hopkins (1981). D e t r i t a l g r a i n s were d e r i v e d from w e a t h e r i n g of l o c a l s i l i c i f i e d P a l e o z o i c c a r b o n a t e s and s h a l e s , and J u r a s s i c and E a r l y C r e t a c e o u s e l a s t i c s , w i t h an a d d i t i o n a l component i n t r o d u c e d from a metasedimentary and p l u t o n i c s o u r c e t o the e a s t , the Precambrian S h i e l d . At t h e time of d e p o s i t i o n , the Sweetgrass Arch was p r o b a b l y a subdued topo-g r a p h i c f e a t u r e , p e r m i t t i n g u n i n h i b i t e d f l o w of d e t r i t u s from s o u t h w e s t e r n Saskatchewan i n t o A l b e r t a . L a t e Neocomian t o A p t i a n u p l i f t of the Sweetgrass A r c h and S w i f t C u r r e n t P l a t f o r m , e a s t of the D r u m h e l l e r a r e a , r e s u l t e d i n i n c i s i o n of an e x t e n s i v e d r a i n a g e network r a d i a t i n g away from the h i -g h l a n d . The u p l i f t i s r e c o r d e d i n the sedimentary r e c o r d of the D r u m h e l l e r sands by d i l u t i o n of c h e r t wackes by w e l l rounded q u a r t z g r a i n s and sedimentary rock fragments d e r i v e d from e r o s i o n of p r e - e x i s t i n g J u r a s s i c sands (Rosary sand) and 1 35 e a r l i e r C r e t a c e o u s s e d i m e n t s , which had been d e p o s i t e d over the Sweetgrass A r c h a r e a . These q u a r t z o s e sandstones were d e p o s i t e d i n b r a i d e d and meandering c h a n n e l s , o c c a s i o n a l l y s c o u r i n g i n t o u n d e r l y i n g c h e r t s a n d s t o n e s . More commonly, the t r a n s i t i o n i s r e c o r d e d by a g r a d a t i o n a l c o n t a c t between u n i t s . T h i s u p l i f t i s r e c o r d e d as a s i g n i f i c a n t u n c o n f o r m i t y i n Saskatchewan, marking a r e v e r s a l i n l o c a l d r a i n a g e d i r e c -t i o n s and sediment source (Beck e t a l . , 1980). In the Dr u m h e l l e r a r e a , the d i r e c t i o n of d r a i n a g e may have a l t e r e d s i i g h t l y . D u r i n g the L a t e A l b i a n , the Mo o s e b a r - C l e a r w a t e r Sea t r a n s g r e s s e d i n t o s o u t h e r n A l b e r t a , r e s u l t i n g i n p r o g r e s s i v e submergence of the b r a i d p l a i n complex and d e p o s i t i o n of b r a c k i s h water muds, s i l t s , and reworked sands, over former a l l u v i a l and l a c u s t r i n e d e p o s i t s . In the study a r e a , the youngest C a l c a r e o u s Member beds host a b r a c k i s h water fauna, and e x h i b i t wavy and l e n t i c u l a r b e d d i n g . In s e v e r a l c o r e s p y r i t e cement was abundant i n the uppermost D r u m h e l l e r sand-stone beds where drowning of l o c a l r i v e r v a l l e y s i s sug-g e s t e d . The presence of l a r g e q u a n t i t i e s of p y r i t e c o u l d be acco u n t e d f o r by i n v a s i o n of b r a c k i s h or marine waters i n t r o -d u c i n g a sou r c e of s u l p h a t e . At the c l o s e of the Lower M a n n v i l l e , C a l c a r e o u s Member f i n e s were a c c u m u l a t i n g a c r o s s the e n t i r e study a r e a i n t e r p r e t e d as an e s t u a r y formed from drowning of the Edmonton Channel and i t s t r i b u t a r i e s . L o c a l p a l e o h i g h s a s s o c i a t e d w i t h the p r e - C r e t a c e o u s p a l e o t o p o g r a p h y had been b u r i e d . D e p o s i t i o n of Carbon q u a r t z o s e sands c o r r e -1 36 l a t i v e with the Glauconitic sands of the Edmonton area re-f l e c t s coastal sedimentation with deposition of d i s t r i b u t a r y sands in estuarine channels contemporaneous with the upper Calcareous Member beds. The l i t h i c Three H i l l s sandstones were deposited in channels on flood and de l t a i c plains as a sea l e v e l drop lead to f i l l i n g of the estuary. It has been suggested that solution of underlying middle Devonian P r a i r i e evaporite influenced evolution of the Mannville Basin (Beck et al.1980) however, no evidence of rapid subsidence due to solution was recognized in the study area. Stages in the sed-imentary history during the early Cretaceous in the Drumheller area are i l l u s t r a t e d in Figure 41. 7.2. CLIMATIC SETTING During the Mesozoic, the paleoclimate of North America was warm and equable. No evidence of gl a c i a t i o n has been re-corded in the sedimentary record (Habicht, 1980). Oxygen iso-tope data from carbonates of the Jurassic and Cretaceous Periods suggest warm temperatures even in polar latitudes of the time (Habicht, 1980). During the Jurassic, oxygen iso -topes indicate an average annual near surface water tempera-ture of 24° c in east central Alberta. The paleolatitude of Drumheller at that time was approximately 47° North (Habicht, 1980). Redbeds and evaporites are commonly found in the Jurassic section south of the study area, suggesting a r i d condit ions. The Cretaceous was marked by increased humidity in North 137 F i g u r e 4 1 . D e p o s i t i o n a l m o d e l f o r L o w e r M a n n v i l l e G r o u p s e . d i m e n t s ( s e e n e x t p a g e f o r t e x t ) . 138 F i g u r e 41. Four s t a g e s i n the d e p o s i t i o n a l h i s t o r y of t h e M a n n v i l l e Group i n the D r u m h e l l e r a r e a a r e p r e s e n t e d i n e a s t - w e s t c r o s s - s e c t i o n s , A t h r o u g h D. The base l e v e l a t each stage i s i n d i c a t e d by the dashed l i n e . A. D u r i n g the L a t e J u r a s s i c - E a r l y C r e t a c e o u s , D e v i l l e b r e c c i a s were d e p o s i t e d as d e b r i s f l o w s on a l l u v i a l f a n s . P a l e o s o l s were d e p o s i t e d i n t h e h i g h e r a r e a s . Immature c h e r t y sands were d e p o s i t e d i n b a r s of low s i n u o s i t y , sandy, b r a i d e d r i v e r s contemporaneous w i t h the D e v i l l e F o r m a t i o n i n v a l l e y s d e f i n e d by p o s t - P a l e o z o i c e r o s i o n . B. D u r i n g the E a r l y C r e t a c e o u s (Neocomian), base l e v e l s l e a d t o f i l l i n g i n of low r e l i e f d e f i n e d by the p r e - C r e t a c e o u s u n c o n f o r m i t y . B r a i d e d streams d e p o s i t s formed e x t e n s i v e sheet sands. D i l u t i o n of c h e r t r i c h sands by q u a r t z d e r i v e d from a p r e - e x i s t i n g sandstone i n d i c a t e s u p l i f t i n the source a r e a b e l i e v e d t o be i n the s o u t h e a s t . Contemporaneous d e p o s i t i o n of C a l c a r e o u s Member f i n e s o c c u r e d i n a l a c u s t r i n e environment i n the western h a l f of the s t u d y a r e a . S m a l l l a c u s t r i n e d e l t a d e p o s i t s a r e p r e s e n t a t the w e s t e r n edge of the D r u m h e l l e r sand s h e e t . C. With southward t r a n s g r e s s i o n of the C l e a r w a t e r - M o o s e b a r Sea, the study a r e a became p a r t of an e s t u a r y or embayment, r e c o r d e d by b r a c k i s h water fauna i n t h e uppermost beds of t h e C a l c a r e o u s Member. Beaches and d e l t a s formed a t the margins of t h i s s h a l l o w embayment. N o r t h w e s t -s o u t h e a s t t r e n d i n g e s t u a r i n e c h a n n e l s , the submature, f i n e g r a i n e d sandstones of the Upper M a n n v i l l e Carbon s a n d s t o n e s , were formed. D. With n o r t h w a r d r e g r e s s i o n of the sea d u r i n g the e a r l y A l b i a n , f l u v i a l sediments were d e p o s i t e d on a low r e l i e f c o a s t a l p l a i n . These sediments c h a r a c t e r i z e d by an abundance of f e l d s p a r and l i t h i c f r a g m e n t s , such as c o u l d have been d e r i v e d from the southwest. 1 39 America, possibly related to large scale marine transgres-sions and b i r t h of oceanic c i r c u l a t i o n in the North A t l a n t i c (Gulf Stream) (Habicht, 1980). Estimated mean annual tempera-tures were 10 to 15 degrees warmer than today (Habicht, 1980). Indicators of a r i d i t y such as evaporites and widespead development of red beds are lacking. Some seasonal a r i d i t y however was suggested by Walker (1974). Mountain building in the west could have resulted in some influence by a rain sha-dow. The presence of ka o l i n i t e cemented sands, however, sug-gests intensive leaching in areas of good drainage with a humid climatic setting. Acidic conditions favour the forma-tion of k a o l i n i t e whereas alkaline conditions more commonly result in formation of smectites or mica. The presence of coal preserved in the Mannville sequence also suggests a moist climate. 7.3. UNCONFORMITIES OF THE LOWER MANNVILLE One objective of t h i s project was to study the r e l a t i o n -ship between erosion and deposition, examining Lower Mannville sedimentation patterns as related to the r e l i e f carved in Paleozoic strata. Four periods of post-Carboniferous and pre-Cretaceous erosion have been documented in the statigraphic record of Southern Alberta: (1) late Pennsylvanian to early Permian, (2) late Permian to early T r i a s s i c , (3) late T r i a s s i c to early Jurassic and (4) the immediate pre-Cretaceous. The l a t e s t removed most evidence of previous erosional cycles (Boreski, 1978). 1 40 Where e r o s i o n p r e v a i l s over an e x t e n s i v e p e r i o d of t i m e , a w e a t h e r i n g c r u s t ( p a l e o s o l ) d e v e l o p s . The t h i c k n e s s and c o m p o s i t i o n of the mantle a r e dependent upon bedrock l i t h o l o -gy, c l i m a t e , and l o c a l t o p o g r a p h i c r e l i e f . In the D r u m h e l l e r a r e a , sediments of the D e v i l l e F o r m a t i o n a r e p r o d u c t s of wea-t h e r i n g of P a l e o z o i c c a r b o n a t e s and s h a l e s . I n i t i a l w i d e s p r e a d s e d i m e n t a t i o n i s r e c o r d e d by d e p o s i -t i o n of the D r u m h e l l e r sands. The a l l u v i u m was d e p o s i t e d i n v a l l e y s c a r v e d d u r i n g a p r e v i o u s p e r i o d which was c h a r a c t e r -i z e d by h i g h e r stream energy, p r o b a b l y a l s o by h i g h e r stream g r a d i e n t s than d u r i n g the E a r l y C r e t a c e o u s . D i s t r i b u t i o n , t h i c k n e s s , and f a c i e s changes w i t h i n the D r u m h e l l e r Sandstone u n i t can be d i r e c t l y r e l a t e d t o the average p a l e o t o p o g r a p h y of the p r e - C r e t a c e o u s s u r f a c e . W i t h i n the a l l u v i a l sands, l o c a l d i a s t e m s a r e marked by r o o t e d s i l t h o r i z o n s , scoured b a s a l c o n t a c t s and s i g n i f i c a n t changes i n sandstone l i t h o l o g i e s , r e f l e c t i n g s h i f t i n g of c h a n n e l p o s i t i o n s . Two sandstone l i t h o l o g i e s were noted i n the D r u m h e l l e r Sandstone u n i t . The c o n t a c t between the two sands i s g r a d a t i o n a l i n some p l a c e s and s h a r p e l s e w h e r e . As a r e s u l t , t h e r e i s a l a c k of r e g i o n a l c o n t i n u i t y of i n d i v i d u a l sandstone u n i t s . The e x i s t e n c e of t e x t u r a l l y s i m i l a r but com-p o s i t i o n a l l y d i s t i n c t sands c r e a t e s a m b i g u i t y i n c o r r e l a t i o n where g e o p h y s i c a l w e l l l o g s a l o n e a r e used f o r e n v i r o n m e n t a l i n t e r p r e t a t i o n . T h i s p r i n c i p l e i s i l l u s t r a t e d i n F i g u r e 42. In case 1, the presence of two sands may go u n d e t e c t e d . In case 2, i t i s d i f f i c u l t t o c o r r e l a t e between l o g s . As i n case 141 1, s t r a t i g r a p h i c a l l y younger sandstones may be found i n v a l -l e y s which a re deeper than those c u t d u r i n g p r e v i o u s e r o s i v e e v e n t s , c o m p l i c a t i n g d e l i n e a t i o n of i n d i v i d u a l u n i t s . In F i g u r e 43, w i t h o u t c o r e c o n t r o l , the t h r e e s a n d s t o n e s , two D r u m h e l l e r sands w i t h d i f f e r e n t r e s e r v o i r c h a r a c t e r i s t i c s , and the E l l e r s l i e sand, may m i s t a k e n l y be mapped as one u n i t . Sediment d i s t r i b u t i o n and f a c i e s of the C a l c a r e o u s Member were i n f l u e n c e d by the p r e - C r e t a c e o u s p a l e o t o p o g r a p h y . I n i t i a l l y d e p o s i t s were c o n f i n e d t o a low i n the western s e c t o r of the study a r e a . With drowning, f i n e s of the C a l c a r e o u s Member extended i n t o t r i b u t a r y v a l l e y s t o the e a s t . At the c l o s e of the Lower M a n n v i l l e , the r e l i e f on the p r e - C r e t a c e o u s s u r f a c e appears t o have been l a r g e l y f i l l e d w i t h i n the D r u m h e l l e r a r e a ; the l a t e s t sediments of the C a l c a r e o u s Member o v e r l a p p a l e o h i g h s . The t r a n s i t i o n from Lower M a n n v i l l e t o Upper M a n n v i l l e r e p r e s e n t s the c l o s e of a p e r i o d of s e d i m e n t a t i o n i n which p a t t e r n s were c o n t r o l l e d by a topography c a r v e d by an e a r l i e r e r o s i v e p e r i o d , as w e l l as by the change i n sediment provenance d e f i n e d by G l a i s t e r (1959). The Lower M a n n v i l l e sediments of the D r u m h e l l e r a r e a e x e m p l i f y the type of c o n t i n e n t a l s e d i m e n t a t i o n p a t t e r n s which d e v e l o p a f t e r a p e r i o d of wi d e s p r e a d e r o s i o n . S i m u l t a n e o u s e r o s i o n and d e p o s i t i o n d e f i n e l i t h o l o g i c pac-kages which a re c o m p l e x l y i n t e r r e l a t e d . Unambigious c o r r e l a -t i o n of sands over a r e a s w i t h poor w e l l c o n t r o l i s d i f f i c u l t or i m p o s s i b l e . 142-C O R R E L A T I O N CASE 1 B F i g u r e 42. C o r r e l a t i o n problems t y p i f y the D r u m h e l l e r Sandstones (see t e x t f o r e x p l a n a t i o n of Case 1 and 2 ) . 143 7-17-28-20 W4 ( 4 5 0 0 - 4 5 8 5 ) I * S.P. R e s i s t i v i t y F i g u r e 4 3 . T h e c o m p l e x d i s t r i b u t i o n o f l i t h o l o g i c a l l y d i f f e r e n t s a n d s i n t h e M a n n v i l l e B a s i n l e a d s t o m i s c o r r e l a t i o n o f u n i t s w h e r e c o r e i s a b s e n t . I n 7 - 1 7 - 2 8 - 2 0 W4, 3 d i s t i n c t s a n d s t o n e s a r e p r e s e n t . W h e r e i n t e r p r e t a t i o n i s b a s e d o n l o g a n a l y s i s o n l y , o n e o r t w o u n i t s may h a v e b e e n r e c o g n i z e d . 1 44 V I I I . REVISION OF STRATIGRAPHIC TERMINOLOGY I t i s proposed t h a t the s t r a t i g r a p h i c column f o r Lower M a n n v i l l e sediments of the D r u m h e l l e r area be r e v i s e d . The c u r r e n t nomenclature does not a d e q u a t e l y r e f l e c t the l i t h o -s t r a t i g r a p h i c n a t u r e and c o m p l e x i t i e s observed i n the se-quence . The age of the D e v i l l e F o r m a t i o n i s v a r i a b l e throughout A l b e r t a . In the study a r e a i t p r o b a b l y ranges from L a t e J u r a s s i c t o E a r l y C r e t a c e o u s . W i t h i n the B a s a l Q u a r t z u n i t , two p a r t l y c o e v a l sandstone l i t h o l o g i e s have been r e c o g n i z e d , a c h e r t sandstone e q u i v a l e n t t o the Success sands of Saskatchewan, and a q u a r t z o s e sandstone. The name B a s a l Q u a r t z has been d i s c a r d e d i n f a v o u r of the D r u m h e l l e r Sandstone. The E l l e r s l i e F o r m a t i o n i s l o c a l l y p r e s e n t ; i t has been d a t e d as Barremian i n the study a r e a . The s i m u l t a n e o u s d e p o s i t i o n of p a r t s of the C a l c a r e o u s Member, w i t h the E l l e r s l i e , and D r u m h e l l e r Sandstones can be r e c o g n i z e d . The G l a u c o n i t i c Sandstone c o r r e l a t i v e has been renamed and d i -v i d e d i n t o two l i t h o s t r a t i g r a p h i c u n i t s , the Carbon Sandstone Member and the Three H i l l s s a ndstone. The Carbon Sandstone was d e p o s i t e d i n p a r t , contemporaneous w i t h sediments of the C a l c a r e o u s Member. A r e v i s e d s t r a t i g r a p h i c column i s p r e -s e n t e d i n Ta b l e IV. 145 CO Z) o LU o < LU cc o cc LU CO CO < cc Stage ALBIAN APTIAN BARREMIAN < O O o UJ z . HAUTERIVIAiNI VALANGINIAN BERRIASIAN CL Z) O cc o LU > z Drumheller Area a a Grand Rapids Fm. Three Hills Sst. Carbon Mbr. Calcareous Mbr. \ Ellersli e Fm. Dnjmheller Sst. Deville Fm. T a b l e IV. R e v i s e d s t r a t i g r a p h i c column f o r the s t u d y a r e a , 1 46 IX. DIAGENESIS OF THE DRUMHELLER (BASAL QUARTZ) SANDS 9.1. INTRODUCTION Several stages in the diagenesis of the Drumheller Sandstones have been recognized from textures observed petro-graphically and with the scanning electron microscope. Early p r e c i p i t a t i o n of authigenic s i d e r i t e in a reducing environ-ment was followed by formation of quartz overgrowths, do-lomite, c a l c i t e , barite, p y r i t e , and ka o l i n i t e cements, and a period of s i d e r i t e solution, which led to the development of l o c a l i z e d secondary porosity. The net effect has been to create a potential reservoir with an irregular d i s t r i b u t i o n of porosity and permeability controlled by l o c a l diagenetic environments within the sediment. 9.2. STAGES OF DIAGENESIS Diagenetic reactions have been subdivided into three stages by Choquette and Pray (1970): (1) eogenetic—at or near the sediment water interface, where the chemistry of the i n t e r s t i t a l water is controlled mainly by the surface en-vironment; (2) mesogenetic--characterized by cementation, compaction and.mineral replacement; and (3) t e l o g e n e t i c — a s -sociated with u p l i f t and subaerial exposure. Although de-signed for carbonate rocks, th i s nomenclature applies equally well to s i l i c i c l a s t i c sediments (Schmidt and MacDonald, 1 4 7 1979) . 9.2.1. Eogenetic Stage Pre c i p i t a t i o n of S i d e r i t e : Formation of s i d e r i t e (FeCo3), the e a r l i e s t cement in the Drumheller Sandstones, occurred early during b u r i a l in a reducing environment d i r e c t l y below the oxidizing zone at the sediment water interface. In a r g i l l a -ceous facies s i d e r i t e concretions and spherulites are common; in sandstones s i d e r i t e i s found as i n t e r s t i t i a l cement, spherulites, and euhedral c r y s t a l s . A higher percentage of s i d e r i t e was noted in finer sediments and in muddy sands ad-jacent to shales, a d i s t r i b u t i o n similar to that reported by Hawkins (1978) in the Bothamsall O i l F i e l d , England. The conditions under which s i d e r i t e i s thermodynamically stable are severely r e s t r i c t e d . A low Eh i s required as well as sulphide and calcium concentrations s u f f i c i e n t l y low such that iron i s not consumed by formation of pyrite and car-bonate by c a l c i t e . The most l i k e l y environment for s i d e r i t e p r e c i p i t a t i o n occurs where Eh ranges from -0.25 v to +0.35 v, sulphide a c t i v i t y i s near zero, and water c i r c u l a t i o n i s re-s t r i c t e d (Curtis and Spears, 1968). The formation of iron carbonate, rather than calcium carbonate, requires an iron to calcium r a t i o greater than 0.05 (Berner, 1971). Primary pre-c i p i t a t i o n of s i d e r i t e in a system open to the atmosphere i s improbable; early diagenetic p r e c i p i t a t i o n i s more l i k e l y , in equilibrium with sediment pore waters. In argillaceous sedi-ments, conditions conducive to the formation of s i d e r i t e can 1 48 e x i s t near the sediment-water i n t e r f a c e ; the r e q u i r e d r e -s t r i c t e d water c i r c u l a t i o n w i l l be e n c o u n t e r e d o n l y a t g r e a t -er depths i n c o a r s e r d e p o s i t s . S i d e r i t e i s a r e l a t i v e l y common component of a n c i e n t non-marine sediments, where i t i s found a s s o c i a t e d w i t h c o a l beds and f r e s h w a t e r c l a y s ( B e r n e r , 1971; Gould and Smith, 1979; Matsumoto and I i j i m a , 1981; Spears and Amin, 1981). In non-marine environments, c o n d i t i o n s c o n d u c i v e t o s i d e r i t e p r e c i p i t a t i o n are e s t a b l i s h e d e a r l y i n d i a g e n e s i s , whereas i n marine environments p y r i t e tends t o be p r e c i p i t a t e d because l a r g e q u a n t i t i e s of s u l p h i d e are produced. I f p r e s e n t , s i -d e r i t e i s l i k e l y t o be a l a t e d i a g e n e t i c m i n e r a l i n marine s e d i m e n t s , a l t h o u g h G a u t i e r (1982) has r e c e n t l y r e p o r t e d e a r l y d i a g e n e t i c s i d e r i t e c o n c r e t i o n s i n C r e t a c e o u s marine s h a l e s . The h i g h c o n c e n t r a t i o n of c a l c i u m i n marine waters ( i r o n / c a l c i u m r a t i o l e s s than 0.01 ( B e r n e r , 1971)) a l s o i n h i -b i t s s i d e r i t e p r e c i p i t a t i o n (Spears and Amin, 1981). H i g h e r c o n c e n t r a t i o n s of s i d e r i t e i n the f i n e r sediments and p r o x i m a l t o sandstone-mudstone i n t e r f a c e s i n sandstones may be r e l a t e d t o a h i g h e r c o n c e n t r a t i o n of i r o n i n a s s o c i a -t i o n w i t h c l a y s and i o n i c impedances e s t a b l i s h e d d u r i n g dewa-t e r i n g of c l a y s . I r o n c o u l d be i n t r o d u c e d c o l l o i d i a l l y as o r g a n i c c h e l a t i n complexes (humates and f u l v a t e s ) or as c o a -t i n g s on d e t r i t a l k a o l i n i t e and o t h e r g r a i n s . C o a t i n g s as f e r r i c o x i d e s and h y d r o x i d e s would be c o n v e r t e d under reduc-i n g c o n d i t i o n s t o s o l u b l e f e r r o u s i r o n where o r g a n i c m atter i s abundant. F e r r o u s i r o n , c ombining w i t h c a r b o n a t e , w i l l 1 49 result in the production of s i d e r i t e . The association of s i d e r i t e with k a o l i n i t e - r i c h facies as noted by Matsumoto and Iijima, (1981), and Carozzi (i960), also occurs in the Drumheller sandstones. (Plate 14). This commmon association suggests a genetic relationship, the de-f i n i t i o n of which i s not clear. In Japanese coal f i e l d s , s i -derite has been observed to replace k a o l i n i t e (Matsumoto and Iijima (1981)). Sphaerosiderite grains are common in the Basal Quartz sediments. Localized growth of these concretionary bodies during early diagenesis most l i k e l y r e f l e c t s establishment of microenvironments p a r t i a l l y controlled by b a c t e r i a l a c t i v i t y and the d i s t r i b u t i o n of organic matter in the sediment. Sid e r i t e concretions with organic nuclei were observed by Matsumoto and Iijima (1981) in the Japanese C o a l f i e l d s . Several mechanisms for formation of these bodies have been suggested in the l i t e r a t u r e . Gould and Smith (1979) describe disseminated s i d e r i t i c spherulites, associated with Australian Permian coals which resulted from f i x a t i o n of C02 liberated during early anaerobic fermentation of organic ma-t e r i a l s . Greensmith (1978) suggested leaching of iron from s o i l s by organic acids and i t s concentration at the l o c a l water table where reducing conditions ex i s t , as the mechanism for formation of s i d e r i t e spherulites. Carozzi (1960) sug-gested formation by r e c r y s t a l l i z a t i o n of s i d e r i t e o r i g i n a l l y disseminated in the argillaceous groundmass. Within the Drumheller Sandstones s i d e r i t e with textures 150 P l a t e 14. S.E.M. Ph o t o g r a p h s o f S i d e r i t e and P o r e F i l l i n g K a o l i n i t e . A. A u t h i g e n i c rhombohedral s i d e r i t e w i t h k a o l i n i t e ( 1 0 -23-27-20 W4, 1484.2 m e t r e s ) B. S i d e r i t e (S) and K a o l i n i t e ( K ) . Note t h e development o f d e l i c a t e k a o l i n i t e b o o k l e t s . (10-23-27-20 W4) 151 s i m i l a r t o o o i d s was noted ( P l a t e 7 ) . S p h a e r o s i d e r i t i c o o i d s h a v i n g c o n c e n t r i c l a y e r i n g r e s u l t i n g from a l t e r n a t i n g s i -d e r i t e and k a o l i n i t e have been r e c o g n i z e d , i n a s s o c i a t i o n w i t h k a o l i n i t i c o o i d s ( C a r o z z i , 1960). S i d e r i t i c o o i d s have been found r e p l a c i n g chamosite i n the i r o n s t o n e s of the Northampton Sand I r o n s t o n e ( C u r t i s and Spe a r s , 1 9 6 8 ) . G r e e n s m i t h (1978) r e c o r d s c a s e s i n which s i d e r i t e r e p l a c e d c a l c i t i c o o i d s , removing a l l t r a c e s of the o r i g i n a l m a t e r i a l . P r i m a r y f l u v i a l c a l c i t i c o o i d s were observed by McGannon (1975). The o o l i t h i c t e x t u r e o b s e r v e d i n the D r u m h e l l e r sand-s t o n e s i s p r o b a b l y due t o z o n i n g produced by cha n g i n g pore water c o n d i t i o n s , as opposed t o replac e m e n t . T h i s however was not c o r r o b o r a t e d i n samples examined w i t h the SEM-EDS, sugge-s t i n g t h a t the pore f l u i d s r e s p o n s i b l e f o r p r e c i p i t a t i o n of a u t h i g e n i c s i d e r i t e i n those samples were homogenous ( P l a t e 15) . 9.2.2. Mesogenetic Stage Sediment Compact i o n : I n i t i a l compaction of the D r u m h e l l e r Sands i s shown by bending of a r g i l l a c e o u s rock fragments around l e s s d u c t i l e d e t r i t a l g r a i n s ( P l a t e 16). Compaction r e s u l t e d i n a g e n e r a l r e d u c t i o n of p o r o s i t y , g r e a t e s t i n zones where the c l a y f r a c t i o n was h i g h e s t . Some compaction may have o c c u r r e d i n the e o g e n e t i c stage of d i a g e n e s i s , a l -though f r a c t u r i n g of s i d e r i t e s u g g e s t s t h a t major compaction was l a t e r . Q u a r t z Overgrowths: C r y s t a l l i z a t i o n of s y n t a x i a l q u a r t z o v e r -152 A. S i d e r i t e s p h e r u l i t e , b a c k s c a t t e r e d image (14-10-27-20 W 4, 1394.7 m e t r e s ) . B. I r o n d i s t r i b u t i o n map o f t h e above, d i s p l a y i n g no o b v i o u s z o n i n g (14-10-27-20 W4, 1394.7 m e t r e s ) . 1 53 P l a t e 16. Compaction and s i l i c a m o b i l i z a t i o n . A. Compaction of a mud c l a s t about l e s s d u c t i l e g r a i n s , (x257, 14-15-27-20 W4, 1367.3 m e t r e s ) . B. & C. M o b i l i z a t i o n of s i l i c a and f o r m a t i o n of overgrowths i n a r e a s w i t h a v a i l a b l e pore space, (x64, 10-14-27-20 W4, 1368.7 metres) . 1 54 growths occurred in zones which were r e l a t i v e l y free of de-t r i t a l clays and had good, mainly secondary, porosity (Plates 16 and 17). The o r i g i n of the secondary porosity i s not com-pl e t e l y understood, but may be related to early solution of carbonate detritus and s i d e r i t e by meteoric waters. Overgrowths formed after moderate compaction, as i s shown by tangential grain contacts which existed before s i l i c a p r e c i -p i t a t i o n . Deposition of at least some authigenic s i l i c a oc-curred after formation of s i d e r i t e concretions and cement as quartz euhedra were observed in cracks within the s i d e r i t e . F l u v i a l or surface waters, which at present average 0.013 g" 1 dissolved s i l i c a , are adequate to i n i t i a t e p r e c i p i -tation of quartz in pore spaces, but i n s u f f i c i e n t to produce s i g n i f i c a n t volumes of quartz unless flow volume i s great (Blatt, 1979). The s o l u b i l i t y of quartz i s 0.006 g" 1per cc at shallow depths but increases f a i r l y rapidly with depth. Within a few hundred metres, the s o l u b i l i t y of quartz exceeds 0.013 g~ 1 per cc, thus preventing the deposition of quartz. However pore waters in the Drumheller Sands may have had greater than average amounts of dissolved s i l i c a i f their pH was greater than 8.5. High pH ground waters might be expected because of high water table l e v e l s in the Mississippian lime-stones in upland areas adjacent to the valleys where the Drumheller and D e v i l l e Sandstones were deposited. Groundwater pH values are commonly high in carbonate t e r r a i n s , even under humid temperate conditions because of buffering of dissolved organic acids by carbonate. Surface waters in southwestern 155 P l a t e 17. Q u a r t z Overgrowths. A. F i n e t o medium g r a i n e d q u a r t z o s e s a n d s t o n e o f t h e B a s a l Q u a r t z ( D r u m h e l l e r ) U n i t . Development o f o v e r g r o w t h i s i n h i b i t e d where d e t r i t a l c l a y s c o a t g r a i n s (7-26-27-20 W 4, 1451.1 m e t r e s ) . B. A u t h i g e n i c q u a r t z p r e d a t e s e x t e n s i v e development o f k a o l i n i t e , (7-26-27-2Q W4, 1451.1 m e t r e s ) . 156 Alberta, where carbonate bedrock i s common, often exceed pH 8.5 (Environment Canada, 1975). Extensive c i r c u l a t i o n of shallow meteoric groundwaters enriched in s i l i c a i s possible in the a l l u v i a l environment as modelled for the Drumheller unit, in the course of supplying water to streams. Transport of grains in waters with high pH may account for the fuzzy and corroded grain boundaries observed in many of the poorly sorted muddy sandstones. Additional s i l i c a may have been released by pressure solution recognized in the sandstones, and migrated l o c a l l y from areas of high to low pressure. In many quartzose sand-stones the process of pressure solution has accounted for increasing the amount of dissolved s i l i c a in pore solutions and stimulating the growth of secondary quartz (Blatt, 1979). In the Drumheller sandstones, pressure solution predating and postdating overgrowth formation was recognized. In the l a t t e r case, s i l i c a released would be expelled with the pore waters. Additional s i l i c a introduced from dewatering of clays would be minimal. S i l i c a from clay diagenesis i s associated with the conversion of smectite to i l l i t e (Siever, 1962), the l a t t e r forming only a very small component of clays within the Drumheller Sandstone. Secondary quartz growth can occasionally produce grain contacts resembling those c h a r a c t e r i s t i c of pressure solu-t i o n . Sipple (1968), using cathodoluminescence, i l l u s t r a t e d the close relationship between overgrowths and pressure solu-t i o n . Several sections of the Drumheller Sandstone were exam-157 i n e d under c a t h o d o l u m i n e s c e n c e t o demonstrate i t s a p p l i c a t i o n i n i d e n t i f i n g overgrowths where l a c k of i n c l u s i o n s and euhe-d r a l c r y s t a l t e r m i n a t i o n s c r e a t e d a m b i g u i t y , and t o examine g r a i n c o n t a c t s t o c o n f i r m the presence of p r e s s u r e s o l u t i o n . S i d e r i t e S o l u t i o n : S i d e r i t e s o l u t i o n i s shown by r e s i d u a l s i d e r i t e w i t h c o r r o d e d margins i n pore spaces ( P l a t e 18). The time r e l a t i o n s between s o l u t i o n of s i d e r i t e and development of q u a r t z overgrowths i n secondary pores a r e ambiguous. From a v a i l a b l e d a t a i t was i m p o s s i b l e t o determine w i t h c e r t a i n t y whether s o l u t i o n of s i d e r i t e l e d t o development of the secon-dary p o r o s i t y i n t o which overgrowths grew. I f t h i s had been the case one would a n t i c i p a t e f i n d i n g i n c l u s i o n s of s i d e r i t e i n o vergrowths as was o b s e r v e d by Hawkins (1978) i n the B o t h a m s a l l O i l F i e l d . The l a c k of i n c l u s i o n s may i n d i c a t e l a t e s o l u t i o n of s i d e r i t e , but then the o r i g i n of the pore spaces i n t o which q u a r t z grew i s p r o b l e m a t i c a l . Other Carbonate Cements: C r y s t a l l i z a t i o n of c a l c i t e , as v e i n s i n f i n e r sediments and as pore f i l l i n g cement i n c o a r s e r sed-iments, was noted i n o n l y a few samples. The r a r e c a l c i t i c cement h o s t s i n c l u s i o n s of q u a r t z , brown o x i d i z e d s i d e r i t e , d o l o m i t e , and carbonaceous m a t t e r . O c c a s i o n a l c a l c i t e i s found i n the c l a y m a t r i x . P r e s s u r e s o l u t i o n of c a r b o n a t e g r a i n s i n a d j a c e n t M i s s i s s i p p i a n s t r a t a , w i t h pore water t r a n s p o r t over l i m i t e d d i s t a n c e s , may account f o r the l a t e c a r b o n a t e cement. D o l o m i t e was a l s o r e c o g n i z e d ; i t formed b e f o r e c a l c i t e , as s m a l l , r a r e e u h e d r a l c r y s t a l s . I t s r o l e i n the D r u m h e l l e r Sands i s not u n d e r s t o o d . 1 58 P l a t e 1 8 . S o l u t i o n of s i d e r i t e . A. Pore i n middle of s i d e r i t e s p h e r u l i t e , (x64, 12-22-27-20 W4, 1366.7 metres). B. S o l u t i o n and r e c r y s t a l l i z a t i o n of s i d e r i t e i n pore v o i d , (x64, 14-10-27-20 W4, 1406.0 metres). C. S i d e r i t e as a r e s i d u a l pore f i l l , (x64, 6-22-27-20 W4, 1382 .8 metres). D. R e s i d u a l s i d e r i t e i n pore. Formation of quartz overgrowths postdates s i d e r i t e , (x64, 14-10-27-20 W4, 1408.0 metres). 159 B a r i t e Cement: The development of a u t h i g e n i c b a r i t e cement o c c u r r e d r e l a t i v e l y l a t e i n the d i a g e n e t i c h i s t o r y of the D r u m h e l l e r Sands, and i s u s u a l l y found i n s t r a t i g r a p h i c a l l y h i g h e s t beds. W e l l c r y s t a l l i z e d b a r i t e p o i k i l i t i c a l l y enc-l o s e s g r a i n s of q u a r t z and s i d e r i t e c r y s t a l s ( P l a t e s 19 and 2 0 ) . The o r i g i n of the b a r i t e i n f r e s h w a t e r sands i s enigma-t i c due t o the p a u c i t y of d i s s o l v e d s u l p h a t e . Barium c o u l d have been t r a n s p o r t e d i n c h l o r i d e s o l u t i o n s from w e a t h e r i n g of f e l d s p a r s . However, the w a t e r s a r e much more l i k e l y t o have been b i c a r b o n a t e s o l u t i o n s ; no c h l o r i d e s o u r c e s a r e known, s u l p h a t e may have been d e r i v e d from a e r o b i c o x i d a t i o n of o r g a n i c m atter or p y r i t e . Hawkins (1978) noted the p r e -sence of b a r i t e cement i n d i s t r i b u t a r y c h a n n e l s a n d s t o n e s , formed by replacement of k a o l i n i t e . The source and mode of f o r m a t i o n of b a r i t e i n f r e s h w a t e r sandstones r e q u i r e s f u r t h e r wor k. A u t h i g e n i c P y r i t e : W i t h i n the D r u m h e l l e r Sands, p y r i t e has been r e c o g n i z e d as f r a m b o i d s , w e l l c r y s t a l l i z e d cubes, and a u t h i g e n i c cement, c o r r o d i n g d e t r i t a l q u a r t z and overgrowths ( P l a t e 2 1 ) . P y r i t e has a l s o been o b s e r v e d i n the c e n t r a l c o r e s of s i d e r i t e c o n c r e t i o n s , e i t h e r h a v i n g r e p l a c e d the i n n e r f a b r i c or f i l l e d a v o i d r e s u l t i n g from e a r l i e r s o l u t i o n of s i d e r i t e . The presence of p y r i t e i n d i c a t e s r e d u c i n g c o n d i t i o n s , low Eh and low pH ( B e r n e r , 1971). The source of i r o n i s most l i k e l y absorbed c o a t i n g s on d e t r i t a l c l a y s , m o d i f i e d a f t e r d e p o s i t i o n i n an a n a e r o b i c environment from f e r r i c o x i d e s t o 1 60 P l a t e 19. L a t e a u t h i g e n i c b a r i t e cement. A. C r y s t a l l i z e d b a r i t e e n c l o s i n g rhombohedral c a r b o n a t e c r y s t a l , c r o s s e d p o l a r i z e d l i g h t , (x64, 7-17-28-20 W4, 1377.0 m e t r e s ) . B. B a r i t e cement p o s t d a t e s f o r m a t i o n of s i d e r i t e (x257, 14-15-27-20 W4, 1366.4 met r e s ) . 161 P l a t e 20. B a r i t e p o r e f i l l i n g cement. A. B a r i t e cement a d j a c e n t q u a r t z g r a i n s and m a t r i x , (7-17-28-20 W4, 1482.2 m e t r e s , p o l i s h e d t h i n s e c t i o n , S.E.M. image). B. A u t h i g e n i c b a r i t e cement i n c o n t a c t w i t h s i d e r i t e & m a t r i x m a t e r i a l (M), (7-17-28-20 W4, 1482.2 m e t r e s , p o l i s h e d t h i n s e c t i o n , b a c k s c a t t e r e d e l e c t r o n image). 162 P l a t e 21. P y r i t e . a s A , f r a m b o i d s , t h e development of w h i c h p o s t d a t e s q u a r t z o v e r g r o w t h , (10-23-27-20 W4, 1485.2 m e t r e s , S.E.M. image o f a f r a c t u r e s s u r f a c e ) , and B, r e p l a c i n g m a t r i x m a t e r i a l ( k a o l i n i t e and q u a r t z ) (7-17-28-20 W4, 1482.2 m e t r e s , p o l i s h e d t h i n s e c t i o n , b a c k s c a t t e r e d e l e c t r o n image). 1 63 f e r r o u s i r o n . P y r i t e forms i n f r e s h water environments as a r e s u l t of the r e a c t i o n between H 2S produced by b a c t e r i a l de-c o m p o s i t i o n of o r g a n i c complexes w i t h i r o n m i n e r a l s . P y r i t e i s c h e m i c a l l y and p h y s i c a l l y u n s t a b l e as a d e t r i t a l m i n e r a l ( B e r n e r , 1971). More than one stage of p y r i t e f o r m a t i o n oc-c u r r e d i n the D r u m h e l l e r s a n d s t o n e s . A u t h i g e n i c C l a y s : C l a y s of both d e t r i t a l and a u t h i g e n i c o r i g i n a re u s u a l l y p r e s e n t i n s a n d s t o n e s . W i l s o n and P i t t m a n (1977) p r e s e n t e d a l i s t of c r i t e r i a which c o u l d be used t o d i s t i n g u i s h between the two forms of c l a y ; t h i s l i s t i s r e -produced i n T a b l e V. The d e t r i t a l f r a c t i o n s h o u l d be more abundant i n the s h a l e s and the a u t h i g e n i c f r a c t i o n i n the s a n d s t o n e s , where p e r m e a b i l i t y and p o r o s i t y a r e g r e a t e r . W i t h i n the D r u m h e l l e r Sandstones k a o l i n i t e dominates i n the c o a r s e r f r a c t i o n , w i t h b o t h i l l i t e and k a o l i n i t e found i n the f i n e r f r a c t i o n . The k a o l i n i t e w i t h i n the sandstones o c c u r s as books of pseudohexagonal k a o l i n i t e c r y s t a l s f i l l i n g p o r e s , i n d i c a t i v e of an a u t h i g e n i c o r i g i n ( P l a t e 2 2 ) . P e t t i John e t a l . (1972) i n t e r p r e t t h e presence of a u t h i g e n i c k a o l i n i t e as s t r o n g e v i d e n c e f o r i n v a s i o n of r e l a t i v e l y f r e s h groundwater from a r e c h a r g e o u t c r o p b e l t i n which t h e r e was a s u p p l y of d i s s o l v e d s i l i c a from c h e m i c a l w e a t h e r i n g . M o n t m o r i l l o n i t e or i l l i t e would have been p r e c i p i t a t e d i f the w a t e r s were not s u f f i c i e n t l y d i l u t e ( B l a t t , 1979). The presence of a u t h i g e n i c k a o l i n i t e i n pores w i l l i n h i b i t h y d rocarbon p r o d u c t i o n from D r u m h e l l e r sandstone r e s e r v o i r s . K a o l i n i t e i s a t t a c h e d l o o s e -l y t o the s u r f a c e of the h o s t g r a i n and tends t o become d i s -164 1. A u t h i g e n i c c l a y s c a n a t t a i n a h i g h d egree of p u r l t y . 2. Some a u t h i g e n i c c l a y s m i n e r a l s u i t e s a r e monomi n e r a l i e . 3. A u t h i g e n i c c l a y s i n s a n d s t o n e s s i g n i f i c a n t l y d i f f e r f rom d e t r i t a l c l a y s i n a s s o c i a t e d mudstone laminae or beds. 4. A u t h i g e n i c pore f i l l i n g c l a y s may e x h i b i t z o n i n g c o n c e n t r i c w i t h p o r e b o u n d a r i e s . 5. C l a y s o f t e n e x h i b i t w e l l c r y s t a l l i z e d h a b i t s , the d e l i c a c y o f t h e c l a y f l a k e s p r e c l u d e s extended t r a n s p o r t . 6. Some a u t h i g e n i c c l a y s e x h i b i t s p i n e o r l a t h l i k e d e l i c a t e p r o t r u d a n c e s . 7. Such c l a y s a r e not deformed by compaction. 8. They c a n form pseudomorphs a f t e r some d e t r i t a l c l a y s . 9. Sandstones c o n t a i n i n g a u t h i g e n i c c l a y s o f t e n e x h i b i t a d i s t i n c t break In g r a i n s i z e d i s t r i b u t i o n , l a c k i n g a s i l t s i z e d component. 10. • A u t h i g e n i c c l a y p a r t i c a l s i n s a n d s t o n e s tend to be l a r g e r than c l a y p a r t i c a l s i n a d j a c e n t d e t r i t a l c l a y laminae. 11. Such c l a y s may form t h i n c o a t i n g s on g r a i n s u r f a c e s , absent at g r a i n t o g r a i n c o n t a c t s . 12. A u t h i g e n i c c l a y s o c c u r as s c a t t e r e d p o r e f i l l i n g s whereas a l l o g e n i c c l a y s tend t o be d i s t r i b u t e d e v e n l y throughout t h e i r zone of o c c u r a n c e . 13. C l a y s p r e s e n t a l o n g f r a c t u r e s a r e a u t h i g e n i c . 14. A u t h i g e n i c c l a y s w i l l be ab s e n t i n t h a t p o r t i o n of a s a n d s t o n e t h o r o u g h l y cemented d u r i n g e a r l y d i a g e n e s i s . 15. A u t h i g e n i c c l a y s form i n laminae w i t h a b r u p t l a t e r a l t e r m i n a t i o n . 16. A u t h i g e n i c c l a y s may c o v e r d i a g e n e i t c components formed at an e a r l i e r s t a g e . 17. A u t h i g e n i c c l a y s may a c t as b r i d g e s between d e t r i t a l g r a i n s near p o i n t s o f c o n t a c t . 18. I n d i v i d u a l f l a k e s of some a u t h i g e n i c c l a y s a r e a l i g n e d r a d i a l l y w i t h r e s p e c t t o d e t r i t a l g r a i n s u r f a c e s . T a b l e V . C r i t e r e a for d i s t i n g u i s h i n g a u t h i g e n i c from d e t r i t a l c l a y s , ( m o d i f i e d from W i l s o n and P i t t m a n , 1977) . 165 P l a t e 22. A. A u t h i g e n i c k a o l i n i t e p o r e f i l l i n t h e D r u m h e l l e r ( B a s a l Q u a r t z ) , c h e r t a r e n i t e , 10-23-27-20 W4, 1484.2 m e t r e s , f r a c t u r e s u r f a c e , S.E.M. Image. B. F i n e b o o k l e t s o f k a o l i n i t e , 10-23-27-20 W4, 1484.2 m e t r e s , f r a c t u r e s u r f a c e , S.E.M. Image. 1 66 lod g e d , m i g r a t i n g i n t o the pore t h r o a t s w i t h f l u i d f l o w . The l a r g e s i z e of i n d i v i d u a l p a r t i c l e s e f f e c t i v e l y b l o c k s pore t h r o a t s . C l a y s were obse r v e d t o p o s t d a t e q u a r t z overgrowths i n s e v e r a l c a s e s . 9.3. RED PIGMENT W i t h i n s i l t y beds of the D r u m h e l l e r s a n d s t o n e s , r e d zones, many showing m o t t l i n g of c o l o u r , a re common. The r e d pigment i s due t o the presence of h e m a t i t e i n the m a t r i x , as c o n f i r m e d by X-ray d i f f r a c t i o n . The o r i g i n of r e d beds has been the s u b j e c t of c o n t r o v e r s y , whether d e t r i t a l or d i a g e n e -t i c . The d i a g e n e t i c p r o c e s s i n c l u d e s a g i n g of brown amorphous f e r r i c o x i d e t o h e m a t i t e . In o r d e r f o r h e m a t i t e t o form from d e h y d r a t i o n of l i m o n i t e , r a t h e r than r e d u c t i o n o c c u r r i n g , the o r i g i n a l sediment would have t o be r e l a t i v e l y f r e e of decom-p o s a b l e o r g a n i c m a t t e r , t o m a i n t a i n a h i g h Eh f o r s t a b i l i z a -t i o n of h e m a t i t e ( B e r n e r , 1971). Walker (1974) s u g g e s t s t h a t the t r a n s f o r m a t i o n of l i m o n i t e t o h e m a t i t e as a d i a g e n e t i c p r o c e s s o c c u r s a t low te m p e r a t u r e s i n d i l u t e g r o u ndwaters, s u g g e s t i n g e a r l y d i a g e n e s i s i n a non-marine environment. The red sediments of the D r u m h e l l e r u n i t r e f l e c t a low water t a b l e where sediment was o x i d i z e d and p e r i o d i c a l l y wet. W i t h i n the o x i d i z e d s i l t s , b l e a c h e d zones a r e c e n t e r e d about o r g a n i c d e t r i t u s , i n d i c a t i n g l o c a l r e d u c i n g c o n d i t i o n s . 1 67 9.4. POROSITY WITHIN THE BASAL QUARTZ SANDS A l l sands begin with primary intergranular pores which are modified in size or destroyed by diagenetic processes. Compaction, cementation, and solution have led to porosity ranging from 0 to 25% in the Drumheller Sandstones, with highest values in the well sorted zones. The heterogeneity in porosity r e f l e c t s differences in i n i t i a l clay content of the sands and l o c a l diagenetic history. Reduction of porosity was most e f f e c t i v e during early b u r i a l with growth of s i d e r i t e and s i l i c a cements. Porosity within the Drumheller Sands i s largely secon-dary, with some residual primary intergranular pore space. Evidence for secondary porosity includes the presence of oversized pores and f l o a t i n g grains, elongate pores, corroded grains, inhomogeneity of packing, and p a r t i a l d i s s o l u t i o n of carbonate cements. These textures are i l l u s t r a t e d in Plate 23. Most secondary porosity in quartz arenites i s the result of mesogenetic leaching of carbonates (Schmidt and MacDonald, 1979). A minor percentage i s due to fracturing of grains, shrinkage, and dissolution of sulphates, evaporites, s i l i -cates and other minerals. The f i r s t mechanism appears to have been active in the Drumheller sands. For dis s o l u t i o n of car-bonate minerals to occur, pore waters must be enriched with carbonic acid. In the eogenetic stage, decarbonatization may result from passage of carbonic acids derived from meteoric and biogenic carbon dioxide. During mesodiagenesis most of 1 68 P l a t e 23. Secondary p o r o s i t y i n the Dr u m h e l l e r sandstones. Evidence f o r secondary p o r o s i t y i n c l u d e f l o a t i n g g r a i n s (A, p l a n e p o l a r i z e d l i g h t , x64, 6-6-26-19, W4, 1404.9, m e t r e s ) , o v e r s i z e d pores (B, pla n e p o l a r i z e d l i g h t , x64, 15-13-27-20 W4, 1374.1 m e t r e s ) , inhomogeneity of p a c k i n g and p a r t i a l d i s s o l u t i o n of cements (C, p l a n e p o l a r i z e d l i g h t , x64, 15-13-27-20 W4, 1374.1 m e t r e s ) , and D, i r r e g u l a r d i s t r i b u t i o n of p o r o s i t y ( p l a n e p o l a r i z e d l i g h t , x64, 8-22-27-20 W4, 1376.7 m e t r e s ) . 169 the carbon dioxide which forms carbonic acid originates from the decarboxylation of organic matter undergoing thermoma-turation (Schmidt and McDonald, 1979). A percentage of secondary porosity of the Drumheller unit formed as the result of p a r t i a l d i s s o l u t i on of s i d e r i t e . S i d e r i t e is commonly found as residual material in enlarged pores or as p a r t i a l sphaerosiderites. Zones within the Drumheller sands in which good primary porosity existed may have acquired early s i d e r i t e cement, arresting further compa-ctio n , which was later removed by d i s s o l u t i o n , r e f l e c t e d by inhomogeneity in packing in the diagenetic product. Secondary porosity formed by dissolution may not lead to good permeabi-l i t y unless the o r i g i n a l constituents were abundant enough to be in contact. Usually isolated pores are formed. In the Drumheller sandstones, formation of isolated pores and poor permeability i s noted in zones which were deposited as muddy sands. In zones lacking d e t r i t a l mud, early cements were de-posited, which upon di s s o l u t i o n , resulted in high permeabil-ty. It is possible that a pore cement other than s i d e r i t e has been t o t a l l y removed, leaving no residual material. In Plate 23 D, some corrosion of quartz may have occurred due to ear-l i e r cementation followed by solution of a c a l c i t e cement. The existence of oversized pores may r e f l e c t d i s s o l u t i o n during eogenesis of d e t r i t a l carbonate grains or plant de-b r i s . It is not unusual for secondary porosity to develop in non-marine sands during exposure to meteoric waters shortly after deposition (Hayes, 1979). 170 The l o c a t i o n of secondary p o r o s i t y i n r e s e r v o i r s can be d i f f i c u l t t o p r e d i c t . The l a t e r a l and v e r t i c a l v a r i a t i o n s i n p o r o s i t y and p e r m e a b i l i t y i n the D r u m h e l l e r s a n d s t o n e s , a re not s t r o n g l y c o n t r o l l e d by the d e p o s i t i o n a l environment, b e i n g i n f l u e n c e d l a r g e l y by pore f l u i d p a t h s and c h e m i c a l c o n d i t i o n s d u r i n g d i a g e n e s i s . 9.5. SUMMARY D i a g e n e s i s of the D r u m h e l l e r sands i s due t o cha n g i n g pore f l u i d c h e m i s t r y r e l a t e d t o the d e p o s i t i o n a l environment, sediment provenance, and t e c t o n i c h i s t o r y of the sands. The p a r a g e n e t i c sequence of e v e n t s i s p r e s e n t e d i n Table V I . E a r l y p r e c i p i t a t i o n of s i d e r i t e o c c u r r e d , f o l l o w e d by o x i d a -t i o n and p a r t i a l s o l u t i o n , l e a d i n g t o development of secon-dary p o r o s i t y . S o l u t i o n of o t h e r m a t e r i a l , c a r b o n a t e d e t r i t u s or a p r e v i o u s cement, c r e a t e d h i g h p o r o s i t y i n some zones. A u t h i g e n i c q u a r t z was p r e c i p i t a t e d as q u a r t z overgrowths i n a v a i l a b l e p o r e s . A u t h i g e n i c b a r i t e , p y r i t e , d o l o m i t e , and k a o l i n i t e were p r e c i p i t a t e d i n the r e m a i n i n g p o r e s , or as rep l a c e m e n t s of m a t r i x m a t e r i a l , r e s u l t i n g i n a sandstone w i t h a complex d i s t r i b u t i o n of p o r o s i t y . The p a r a g e n e t i c sequence p r o v i d e s some i n f o r m a t i o n on the c h e m i s t r y of the pore waters d u r i n g b u r i a l of the sand-s t o n e . I n i t i a l r e d u c t i o n , w i t h a low i r o n t o c a l c i u m r a t i o , i s s uggested by the e a r l y f o r m a t i o n of a u t h i g e n i c s i d e r i t e cement. Some p y r i t e may have formed a t t h i s t i m e . S o l u t i o n of s i d e r i t e r e f l e c t s f o r m a t i o n of c a r b o n i c a c i d i n the i n t e r s t i -STAGE TIME • Sphaerosiderite Formation Siderite Pore Filling Cement Siderite Solution • • • • Quartz Overgrowth Pressure Solution Dolomite Cement • • • Calcite Cement • • • Authigenic Clays Authigenic Pyrite • • • I I B I I I I Barite Cement • • • • Hematite Formation Table V I . Paragenetic sequence for the Basal Quartz sandstones. 1 72 t i a l w a ters w i t h 0 2 d e r i v e d from m e t e o r i c w a t e r s , l o w e r i n g the pH. Lowered pH may have produced c o n d i t i o n s c o n d u c i v e f o r p r e c i p i t a t i o n of q u a r t z , the s i l i c a b e i n g d e r i v e d from c i r c u -l a t i n g ground w a t e r s . T e x t u r a l e v i d e n c e from SEM e x a m i n a t i o n of the D r u m h e l l e r sandstones suggests f o r m a t i o n of a u t h i g e n i c k a o l i n i t e d u r i n g and a f t e r q u a r t z o v e r g r o w t h , d u r i n g f l u s h i n g at s h a l l o w depths by m e t e o r i c w a t e r s . F o r m a t i o n of k a o l i n i t e i s enhanced i n an a c i d i c environment (pH below 7 ) , i n which c o n s t i t u e n t s o t h e r than A l and S i are almost e n t i r e l y removed from the c l a y f o r m i n g system by l e a c h i n g , r e d u c t i o n , or o x i -d a t i o n . D i a g e n e t i c f o r m a t i o n of h e m a t i t e r e q u i r e s good c i r c u -l a t i o n of oxygenated m e t e o r i c waters which may have o c c u r r e d s i m u l t a n e o u s l y w i t h s i l i c a m o b i l i z a t i o n and k a o l i n i t e c r y s -t a l l i z a t i o n , i n zones p r o x i m a l t o the water t a b l e and l a c k i n g s i g n i f i c a n t o r g a n i c m a t e r i a l . W ith f u r t h e r b u r i a l , c a l c i t e , as a pore f i l l i n g cement, was d e p o s i t e d . D e p o s i t i o n of c a l -c i t e r e q u i r e s i n c r e a s i n g the c a r b o n a t e : b i c a r b o n a t e r a t i o i n i n t e r s t i t i a l w aters e i t h e r by i n c r e a s i n g temperature or pH. P y r i t e as a r e p l a c i v e m i n e r a l s u g g e s t s l o c a l r e d u c t i o n and low pH. The l a t e p r e c i p i t a t i o n of b a r i t e , a f t e r s i d e r i t e and q u a r t z , i s not u n d e r s t o o d . 173 X. LOWER MANNVILLE OIL AND GAS PRODUCTION 10.1. TRAPPING MECHANISMS Lower M a n n v i l l e o i l and gas p o o l s i n s o u t h e a s t e r n A l b e r t a a re t r a p p e d by a c o m b i n a t i o n of s t r u c t u r a l and s t r a t -i g r a p h i c mechanisms, o i l a c c u m u l a t i n g i n s t r a t i g r a p h i c t r a p s l o c a t e d on the c r e s t and f l a n k of the northward p l u n g i n g s t r u c t u r a l nose of the Sweetgrass A r c h . P e r m e a b i l i t y p i n -c h o u t s a r e common, as c l e a n q u a r t z sandstones grade i n t o s i l t s t o n e s , s h a l e s and t i g h t s a n d s t o n e s . The c a p p i n g of D r u m h e l l e r sandstones by f i n e muds, s i l t s t o n e s and m a r l s and the e n c l o s u r e of C a l c a r e o u s Member sandstones by s i m i l a r f a -c i e s , p r o v i d e the n e c e s s a r y r e s e r v o i r s e a l . S t r u c t u r a l l y h i g h p o r t i o n s of eroded r i v e r t e r r a c e s w i t h c l o s u r e a r e commonly hydrocarbon b e a r i n g . S h a l l o w d r i l l depths make M a n n v i l l e sandstones a t t r a c t i v e p r o s p e c t s . W i t h i n the study a r e a , 3 f i e l d s produce hydrocarbons from the b a s a l a l l u v i a l sand-s t o n e s , 1 f i e l d from the C a l c a r e o u s Member s a n d s t o n e s , and 5 from the Upper M a n n v i l l e Carbon and Three H i l l s s a n d s t o n e s . A summary of f i e l d c h a r a c t e r i s t i c s i s p r e s e n t e d i n Ta b l e V I I . Hydrocarbon s t a i n e d sands of the D r u m h e l l e r Sandstone are w e l l s o r t e d , f i n e t o medium g r a i n e d s a n d s t o n e s , w i t h 0 t o 10 p e r c e n t c l a y m a t r i x , and minor amounts of s i l i c a and c a r -bonate cement. The s o r t i n g and t e x t u r a l m a t u r i t y of the sands s u g g e s t s t h a t the d i s t r i b u t i o n of good r e s e r v o i r sandstones i s r e l a t e d t o the d e p o s i t i o n a l environment, sands d e p o s i t e d 174 T a b l e VII - OIL AND GAS FIELDS IN THE STUDY AREA FIELD DISCOVERY WELL PRODUCTIVE ZONE PAY TYPE POR % EST . RESERVES IN PLACE Carbon 7 -31 -29 -22W4 Upper G l u a c o n i t i c G 14 7 1 24Bcnr = 43! 9Bcf 7 -31 -29 -22W4 Upper G l a u c o n i t i c G 19 9 3 94Bcm= = 139 •:3Bcf C e s s f o r d 6 -15 -27-- 15W4 Dev i11e G 13 1 0 76Bcm= = 26 . 8Bcf 16--05--27-- 14W4 Bas a l O u a r t z G 18 4 5 47Bcm= = 226 . 3Bcf 14--23--26-- 14W4 GIaucon i 11c G 16 5 0 98Bcm= = 34 . 6Bcf Drumhe11er 3--34--29 - 19W4 O s t r a c o d e G 19 5 0 95Bcm= = 33 . 6Bcf 5--09--30--20W4 G1 aucon i 11c G&O 20 1 1 18Bcm= -41 . 6Bcf Ghost P i n e 10--14--30- 23W4 Pek i sko G 6 1 1 59Bcm= 55 . 8Bcf 2--02--32--22W4 G l a u c o n i t i c C G 19 3 5 53Bcm= 234 . OBcf 1 1 --10--31--32W4 G l a u c o n i t i c B G 15 6 5 32Bcm= 187 .9Bcf 15-- 14--31- 22W4 G l a u c o n i t i c A G , 13 8 4 22Bcm= 149 .OBcf Hussar 10--04- 24- 30W4 Bas a l O u a r t z G 10 1 7 93Bcm= 280 .OBcf 16--10- 25- 2 1W4 G l a u c o n i t i c Sand G 21 0 7 93Bcm= 280 .OBcf Wayne- 10- 22- 28- 20W4 GIauconi t i c G 20 5 4 05Bcm= 143 .OBcf Roseda1e *Bcm = b i l l i o n c u b i c metres *Bcf = b i l l i o n c u b i c f e e t Table VII. Location, porosity, and reserves for o i l and gas f i e l d s in the study area, (Alberta Society of Petroleum Geologists, 1966;1969). 175 from s h e e t f l o w s and reworked on bar t o p s , f o r m i n g the b e s t r e s e r v o i r s . In a b r a i d e d r i v e r e r r a t i c d i s c h a r g e r e s u l t s i n p o o r l y s o r t e d sandstones which a r e o f t e n c l a y bound, l a c k i n g good r e s e r v o i r c h a r a c t e r i s t i c s . In the Wayne O i l f i e l d , ( F i g u r e 2 ) , o i l a c c u m u l a t i o n i s c o n t r o l l e d by v a r i a t i o n s of i n t e r s t i t i a l c l a y c o n t e n t i n a f a i r l y homogenous sand. T h i s sandstone, l i t h o l o g i c a l l y s i m i -l a r t o the D r u m h e l l e r Sandstone, has been c a l l e d the Sunburst Sand by E r i c k s o n and Crewson (1959). T h i s type of t r a p ap-p e a r s c h a r a c t e r i s t i c of the Lower M a n n v i l l e D r u m h e l l e r sand-s t o n e s . Pods of sandstone w i t h good e f f e c t i v e p o r o s i t y may r e f l e c t a r e a s of i n c r e a s e d energy i n the o r i g i n a l d e p o s i t i o n -a l e nvironment, and zones i n which c o n d i t i o n s were c o n d u c i v e t o e x t e n s i v e s o l u t i o n of an e a r l i e r cement. Both c h e r t y and q u a r t z o s e sandstones h o s t h y d r o c a r b o n s , the l a t t e r i n g r e a t e r volumes. The v a r i a b l e c l a y c o n t e n t w i t h i n the D r u m h e l l e r sand-s t o n e s h i n d e r s p r e d i c t i o n of p o r o s i t y t r e n d s . In c o r e , porous i n t e r v a l s s t a i n e d by hydrocarbons were observed a b u t t i n g v e r -t i c a l l y a g a i n s t t i g h t s a n d s t o n e s . As w e l l , the c l a y c o n t e n t of the sandstones poses p r o d u c t i o n problems. C l a y s reduce p e r m e a b i l i t y , r e a c t w i t h d r i l l i n g f l u i d s , and i n c r e a s e s e n s i -t i v i t y of the sandstones t o f r e s h w a t e r . As pore l i n i n g s , c l a y s can e f f e c t i v e l y b l o c k pore t h r o a t s , r e s u l t i n g i n g r e a t -l y reduced p e r m e a b i l i t y i n a sandstone w i t h h i g h t o t a l p o ro-s i t y . The main c l a y of the D r u m h e l l e r sandstones i s kao-l i n i t e , commonly as a u t h i g e n i c pore f i l l . The l a r g e s i z e of 1 76 the k a o l i n i t e b o o k l e t s and t h e i r l o o s e attachment h i n d e r s p r o d u c t i o n . K a o l i n i t e i s c h e m i c a l l y s t a b l e , b e i n g non-reac-t i v e t o many a c i d s , and thus d i f f i c u l t t o remove from a r e -s e r v o i r w i t h o u t f o r m a t i o n damage. Minor i l l i t e i s a l s o p r e -s e n t . I l l i t e i n a sandstone c r e a t e s a l a r g e volume of m i c r o -p o r o s i t y which can b i n d water t o host g r a i n s r e s u l t i n g i n a h i g h i r r e d u c a b l e water s a t u r a t i o n (Almon and D a v i e s , 1981). 10.2. TIME OF OIL EMPLACMENT AND MIGRATION P o s t - h i a t u s a l l u v i a l d e p o s i t s commonly make a t t r a c t i v e h ydrocarbon p r o s p e c t s , u s u a l l y c o n s i s t i n g of medium t o c o a r s e g r a i n e d sand d e p o s i t e d d u r i n g a p e r i o d of b a s i n s u b s i d e n c e . The time of o i l m i g r a t i o n w i t h r e s p e c t t o sediment d i a g e n e s i s u l t i m a t e l y d e t e r m i n e s the q u a l i t y of the r e s e r v o i r . P o r o s i t y and p e r m e a b i l i t y a re d e s t r o y e d or enhanced d u r i n g d i a g e n e s i s , the m i g r a t i o n of hydrocarbons i n t o a r e s e r v o i r a r r e s t i n g f u r -t h e r d i a g e n e s i s . From a comparison between o i l p r o d u c i n g and b a r r e n zones, a l a t e emplacement time was i n f e r r e d f o r the Dr u m h e l l e r Sandstones. Samples examined from p r o d u c t i v e zones demonstrated emplacement of hydrocarbons a f t e r the f o r m a t i o n of s i d e r i t e , a u t h i g e n i c q u a r t z , and a u t h i g e n i c c l a y s ( P l a t e 2 4 ) . The d i s t r i b u t i o n of s t a i n i n g i s r e l a t e d t o zones i n which good p o r o s i t y had been p r e s e r v e d or d e v e l o p e d d u r i n g d i a g e n e s i s . No b a r i t e , p y r i t e , or c a l c i t e was obser v e d i n the hydrocarbon s t a i n e d samples. T h i s cannot be taken as p r o o f f o r h ydrocarbon emplacement b e f o r e f o r m a t i o n of these a u t h i -1 77 P l a t e 24. Time of o i l emplacement. O i l emplacement o c c u r r e d a f t e r c r y s t a l l i z a t i o n of a u t h i g e n i c s i d e r i t e shown by hydrocarbon s t a i n e d c r a c k s i n s p h e r u l i t e s (A, x64, 10-23-27-20 W4, 1379.2), and a f t e r development of a u t h i g e n i c c l a y as a pore l i n i n g (B, x64, 15-23-27-20 W4, 1374.0 m e t r e s ) . In C. (x257, 7-17-28-20 W4, 1375.2 m e t r e s ) , f o r m a t i o n of q u a r t z overgrowth o c c u r r e d b e f o r e m i g r a t i o n of o i l . 1 78 genie cements because of the p a u c i t y of thes e cements i n g e n e r a l . 10.3. SOURCE BEDS C h r i s t o p h e r (1974) argued f o r m i g r a t i o n of o i l i n t o Lower M a n n v i l l e a l l u v i a l sand r e s e r v o i r s of so u t h w e s t e r n Saskatchewan from P a l e o z o i c s o u r c e r o c k s . I n s u f f i c i e n t source r o c k s e x i s t w i t h i n the M a n n v i l l e s e c t i o n . C h r i s t o p h e r ( 1 9 7 4 ) s u g g e s t s t h a t the o i l migated i n t o the M a n n v i l l e of Saskatchewan by f o r m a t i o n waters f l o w i n g from the deeper p a r t of the b a s i n through f r a c t u r e c o n d u i t s i n the P a l e o z o i c r o c k s . The l a t e s t phase of m i g r a t i o n would have c o i n c i d e d w i t h the L a t e C r e t a c e o u s t o Eocene Laramide orogeny w i t h the b u i l d up of p r e s s u r e from the h y d r a u l i c head p r o v i d e d by up-l i f t . In t h i s s t u d y , an attempt t o d e f i n e the so u r c e beds and m i g r a t i o n paths f o r hydrocarbons now t r a p p e d i n Lower M a n n v i l l e r e s e r v o i r s of the D r u m h e l l e r a r e a was not made, however, a m a t u r a t i o n study of c o a l y d e b r i s from the C a l c a r e o u s Zone and G l a u c o n i t i c Sand e q u i v a l e n t showed the s e u n i t s t o be immature w i t h r e s p e c t t o p o t e n t i a l f o r h y d r o c a r -bon f o r m a t i o n (see Appendix 1 ) . A P a l e o z o i c s o u r c e thus ap-pe a r s p r o b a b l e . 1 7 9 X I . CONCLUSION The Lower M a n n v i l l e Group of the D r u m h e l l e r a r e a i s r e -p r e s e n t e d by a complex assemblage of b r e c c i a s , s i l t s t o n e s , s h a l e s , s a n d s t o n e s , and m a r l s d e p o s i t e d i n c o n t i n e n t a l and t r a n s i t i o n a l environments on a u n c o n f o r m i t y of moderate r e l i e f a f t e r a p e r i o d of e x t e n s i v e e r o s i o n . E a r l i e s t s e d i -ments comprise c h e r t b r e c c i a s , maroon s i l t s t o n e s , and gre e n , waxy mudstones, a l l d e r i v e d from the w e a t h e r i n g of the under-l y i n g M i s s i s s i p p i a n l i m e s t o n e s and s h a l e . P o o r l y s o r t e d muddy sa n d s t o n e s , r a n g i n g from c h e r t t o q u a r t z a r e n i t e s , were de-p o s i t e d by sandy, low s i n u o s i t y , b r a i d e d r i v e r s t h a t may have formed a l o c a l base l e v e l f o r a d j a c e n t a l l u v i a l f a n s on which the d e b r i s f l o w s were d e p o s i t e d . D r a i n a g e was ea s t w a r d toward a m a r g i n a l l a k e . W i t h southward t r a n s g r e s s i o n of a n o r t h e r n seaway the c h a n n e l s were drowned, and low energy f r e s h t o b r a c k i s h water f i n e s a ccumulated a c r o s s the study a r e a . The r e l i e f on the b a s a l C r e t a c e o u s u n c o n f o r m i t y e x e r t e d a l a r g e e f f e c t on the d i s t r i b u t i o n of the o v e r l y i n g s t r a t a . As an e x p l o r a t i o n t o o l , mapping the c o n f i g u r a t i o n of the un-c o n f o r m i t y l o c a t e s a c c u m u l a t i o n s of a l l u v i a l s a n d s t o n e . The p e t r o g r a p h i c c o m p o s i t i o n of the M a n n v i l l e sandstones r e f l e c t s the p a l e o t e c t o n i c h i s t o r y of the d e p o s i t i o n a l b a s i n . Sediments of the Lower M a n n v i l l e Group a r e c r a t o n i c , d e r i v e d from l o c a l s o u r c e s and c r y s t a l l i n e and sedimentary t e r r a i n s toward the e a s t , s u b t l e changes i n p e t r o l o g y perhaps i n d i c a -t i n g u p l i f t i n the sour c e a r e a . L i t h i c Upper M a n n v i l l e mo-l a s s e sands were d e r i v e d from a so u t h w e s t e r n s o u r c e , composi-180 t i o n r e f l e c t i n g s e d i m e n t a r y , v o l c a n i c and low grade meta-morphic source r o c k s of the Columbian Orogen. R e s e r v o i r c h a r a c t e r i s t i c s of the Lower M a n n v i l l e sand-s t o n e s are d i f f i c u l t t o p r e d i c t . D r u m h e l l e r sandstones a r e c h a r a c t e r i z e d by r a p i d v a r i a t i o n s i n t e x t u r e . Trends i n p o r o -s i t y a re d i f f i c u l t t o d e f i n e because c o n t r o l i s l a r g e l y by d i a g e n e s i s , o r i g i n a l p o r o s i t y h a v i n g been m o d i f i e d by cemen-t a t i o n w i t h s i d e r i t e , s i l i c a , c a l c i t e , d o l o m i t e , b a r i t e and p y r i t e . Large volumes of a u t h i g e n i c k a o l i n i t e i n pore spaces w i l l reduce p e r m e a b i l t i y d u r i n g p r o d u c t i o n . Sandstone l e n s e s of the C a l c a r e o u s Zone a r e s m a l l and d i f f i c u l t t o l o c a t e w i t h o u t e x c e l l e n t w e l l c o n t r o l . 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Workman, L.E., 1979, The B l a i r m o r e Group i n the s u b s u r f a c e of A l b e r t a : A l b e r t a S o c i e t y of P e t r o l e u m G e o l o g i s t s , 9 t h Annual F i e l d C o n f e r a n c e ; Moose Mountain t o D r u m h e l l e r , p.122-129. Wulf, G.R., 1962, Lower C r e t a c e o u s A l b i a n r o c k s i n the N o r t h e r n Great P l a i n s : American A s s o c i a t i o n of P e t r o l e u m G e o l o g i s t s B u l l e t i n , v. 46, no. 8, p.1371-1415. Z i e g l e r , P.A., 1969, The development of sedimentary b a s i n s i n Western and A r t i e Canada: C a l g a r y , A l b e r t a S o c i e t y of P e t r o l e u m G e o l o g i s t s , 89p. 1 92 Appendix I - VITRINITE REFLECTANCE Introduction The reflectance of the coal maceral v i t r i n i t e can be correlated with the ASTM rank as a measure of the degree of organic metamorphism. In r e l a t i v e l y undisturbed strata of known age, the rank of a coal can be related to depth of b u r i a l , and given geothermal gradient, to temperature. In t h i s study, reflectance measurements were obtained for coal samples from the Calcareous and Glauconitic Members of the Mannville Group in the Drumheller area to determine the c o a l i f i c a t i o n l e v e l of organic matter. The data was used to infer maximum bu r i a l temperature and depth, to strengthen an environmental interpretation, and to evaluate the hydro-carbon generating p o t e n t i a l . Sampling and Methods Twelve samples from core of coal, coaly shale, and sand-stone with coaly debris, were co l l e c t e d from the Glauconitic and Calcareous Members. In one instance i t was possible to hand pick the coaly material from the sandstone; in a l l other cases the organic matter from the c l a s t i c rocks, crushed with a mortar and pestle to minus 60 U.S. Standard mesh, was con-centrated by treatment with 12M HC1 to remove carbonates, followed by bathing in 48% HF to remove other inorganics. Grain mounts for r e f l e c t i o n analysis were prepared by mixing equal amounts of coal pulp and transoptic powder. A base of transoptic powder was added and the mixture heated to 115° C, pressed at 35 MPa in a hydraulic press, and cooled to form a p e l l e t which was subsequently ground and polished. Reflectance measurements were made using a Leitz M.V.P. 2 microscope, equipped with a photomultiplier, stable voltage supply, d i g i t a l readout, polarized quartz iodine lamp, narrow band f i l t e r with a central wavelength of 546 and a 50 power o i l immersion objective. For a l l readings a C a r g i l l immersion o i l of 1.515 ref r a c t i v e index was used. I n i t i a l l y the photomultiplier was standardized with a glass standard of 0.506% Ro. After twenty-five readings were taken from a sample, the photomultiplier was restandardized. Readings were made along traverses with 2 mm separation. Maximum reflectance for each anisotropic v i t r i n i t e grain was recorded. The theory of v i t r i n i t e reflectance measurements i s cov-ered in depth by Castano and Sparks (1974), Stach et a l . , (1975), Davis (1978), and Waples (1980). 1 93 R e s u l t s R e s u l t s are presented i n Table 1-1. L i t t l e p e t r o g r a p h i c v a r i a b i l i t y was noted i n the samples. Most c o n s i s t e d of homo-geneous v i t r i n i t e g r a i n s embedded in a mineral matrix. In one sample, e x i n i t e and i n e r t i n i t e g r a i n s , d i s p l a y i n g o r i g i n a l c e l l t e x t u r e s , were noted ( P l a t e 1-1). The r e f l e c t a n c e values of v i t r i n i t e have been i n t e r -p r e t e d i n terms of the ASTM rank c l a s s i f i c a t i o n , the c o a l s v a r y i n g from sub-bituminous A to high v o l a t i l e bituminous B. The values of r e f l e c t a n c e are p l o t t e d i n F i g u r e 1-1 i n r e l a -t i o n t o t h e i r l o c a t i o n . I s o r e f l e c t a n c e l i n e s were contoured as best p o s s i b l e c o n s i d e r i n g the s p a r c i t y of data. There e x i s t s a trend of i n c r e a s i n g rank from east to west. T h i s can be r e l a t e d to the g r e a t e r depth of b u r i a l f o r these s e d i -ments. Use was made of data and r e s u l t s obtained by Hacquebard (1974) in a study of lower Cretaceous c o a l s of A l b e r t a to a i d i n f u r t h e r i n t e r p r e t a t i o n of t h i s data. Hacquebard determined the rank, using v i t r i n i t e r e f l e c t a n c e , of t h i r t y M a n n v i l l e c o a l samples c o l l e c t e d from c o r e s along a 338 km (210 mile) s e c t i o n a c r o s s the A l b e r t a s y n c l i n e (Figure 1-2). The c o a l s , l y i n g at depths between 600.0 and 3,300 m (1,969 and 10,827 f e e t ) i n c r e a s e d i n c o a l i f i c a t i o n l e v e l from 0.4 Ro to 1.6 Ro from east to west. Near s u r f a c e c o a l s of younger s t r a t a were noted to have a p a r a l l e l i n c r e a s e of rank as determined from measurement of moisture content. The maximum b u r i a l depth had been e s t a b l i s h e d f o r these younger c o a l s (Hacquebard), and by adding t h i s depth to the present subsurface p o s i t i o n of the M a n n v i l l e c o a l s i n r e f e r e n c e to the younger ones, the maximum b u r i a l depth of the M a n n v i l l e c o a l s was obtained. T h i s depth was p l o t t e d a g a i n s t r e f l e c t i o n data, producing the smooth curve of F i g u r e 1-3. T h i s M a n n v i l l e c o a l i f i c a t i o n curve r e -l a t e s only to l a t e r a l changes along an east-west s e c t i o n . A d d i t i o n a l i n f o r m a t i o n on c o a l i f i c a t i o n time and paleotem-p e r a t u r e s was r e q u i r e d to determine the changes i n rank above and below the curve. T h i s was obtained from the c o a l i f i c a t i o n models of Karweil (1956), p r o v i d i n g the i n f o r m a t i o n necessary fo r c o n s t r u c t i o n of the i s o r e f l e c t a n c e contours. With t h i s a d d i t i o n a l data, rank assignments at v a r i o u s depths above and below the M a n n v i l l e can be determined as w e l l as paleothermal g r a d i e n t s . Completed, F i g u r e 1-3 r e p r e s e n t s a three dimen-s i o n a l p i c t u r e of changes i n rank. Although the l i n e of s e c t i o n i s s l i g h t l y north of the study area, Hacquebard's (1975) M a n n v i l l e c o a l i f i c a t i o n curve was used i n a f i r s t approximation i n i n t e r p r e t a t i o n . In t h i s study, the r e f l e c t a n c e of the c o a l s range from 0.538 Ro to 0.686 Ro. From F i g u r e 1-3, t h i s y i e l d s a range in maximum depth of b u r i a l from approximately 2,300 m to 3050 m. Using t h i s method, depths were compiled f o r a l l the samples s t u d i e d and p l o t t e d i n F i g u r e 1-5. From F i g u r e 1-3, the p a l e o g r a d i e n t Petrographic c h a r a c t e r i s i t i c s of the Glauconitic coal d e t r i t u s . A. V i t r i n i t e grains with framboidal pyrite from a thin coal horizon enclosed by black shales, (7-19-30-22W4, 1454.8 metres). B. I n e r t i n i t e ( f u s i n i t e ) from 6-11-28-21 W4, 1388.9 metres, a coal obtained from a r i p up zone at the base of a channels. Note the pyrite framboid in the upper potion of the photo and the excellent preservation of c e l l structure. 1 T a b l e I-I - R e s u l t s from the R e f l e c t i o n A n a l y s i s WELL DEPTH REFL. STND. RANK LOCATION METRES MEAN DEV. 15- 13 -27- 20W4 1367 0 0 609 O 049 Sub-b i turn 1 nous A 6- 15 -27- 23W4 1666 0 0 686 0 024 H i g h v o l 1 t i l e b i turn i nous 10- 13 -28- 19W4 1229 2 M i n e r a l matter 10- 13 -28- 19W4 1225 4 O 595 0 034 Sub-b i turni nous A 10- 36 -28- 20W4 1 190 3 0 596 0 059 Sub-bi tumlnous A 6- 1 1 -28- 20W4 1388 9 0 640 0 039 Sub-b1 turni nous A 9- 14 -28- 21W4 1431 0 M i n e r a l matter 10- 16 -29- 20W4 1316 4 0 538 0 052 Sub-b i turn i nous A 10- 19 -29- 22W4 1454 0 0 666 0 048 Sub-b i turn 1 nous A 10- 35 -29- 22W4 1420 3 0 631 0 057 Sub-b1 turn1 nous A 7- 19 -30- 22W4 1454 8 0 617 0 029 Sub-b1 turn 1 nous A 7- 19 -30- 22W4 1454 8 0 519 0 038 Sub-b1 turn 1 nous A T a b l e I - I . L o c a t i o n of samples, r e f l e c t a n c e means, s t a n d a r d d e v i a t i o n , and A.S.T.M. Rank c l a s s i f i c a t i o n f o r c o a l s a n a l y z e d . 24W4 23W4 22W4 21W4 20W4 19W4 T30 T29 T27 \ , \ A umheller * F i g u r e 1-1. I s o r e f l e c t a n c e l i n e s c o n t o u r e d from the d a t a . Figure 1-2. A. Location of Hacquebard's Alberta cross section (Hacquebard, 1975). B. Location of coal samples and isomoisture contours of near surface coals (Hacquebard. 1975). 197 Paleogradient 2 6 2 6 2 5 2 4 2 4 2 4 2 3 2 3 a Q 1 co 4 € E x -I a ft-Ranki Ro '2000 (-4000 m Figure 1-3. A. The Mannville c o a l i f i c a t i o n curve (Hacquebard, 1975). Figure 1-4. Relationship between rank, temperature, and time of c o a l i f i c a t i o n (after Karweil, 1956; in Hacquebard and Donaldson, 1970.) 1 9 8 Figure 1-5. Contours of maxium b u r i a l depths as interpreted from the reflectance data and model of Hacquebard (1975). 1 9 9 was 2 . 6 ° C 1 0 " 2 m-1. C o r r e s p o n d i n g p a l e o t e m p e r a t u r e s were o b t a i n e d u s i n g K a r w e i l ' s ( 1 9 5 6 ) c o a l model, u s i n g 3 5 Ma as the d u r a t i o n of c o a l i f i c a t i o n f o r M a n n v i l l e c o a l s ( e f f e c t i v e h e a t i n g time) (Hacquebard, 1 9 7 5 ) . For the d a t a from t h i s s t u d y , a range i n maximum tempe r a t u r e s from 8 2 ° C t o 112 ° C was o b t a i n e d . An attempt was made t o a p p l y the method of L o p a t i n ( 1 9 7 1 ) t o e v a l u a t e the l e v e l of o r g a n i c m a t u r a t i o n of t h e sedi m e n t s . To use t h i s method, a r e c o n s t r u c t i o n of the depos-i t i o n a l and t e c t o n i c h i s t o r y of the g e o l o g i c s e c t i o n i s r e q u i r e d , best a c c o m p l i s h e d i n the form of a diagram r e l a t i n g depth of b u r i a l t o g e o l o g i c age. For the sediments s t u d i e d , t h i s has been done i n F i g u r e 1 - 5 , assuming maximum b u r i a l of 3 0 5 0 m, and a p r e s e n t depth of 1 5 2 5 m. I t i s f u r t h e r assumed t h a t u p l i f t o c c u r r e d a f t e r d e p o s i t i o n of t h e Edmonton Fo r m a t i o n a t the base of the P a l e o c e n e . Most w e l l s i n the are a a r e spudded i n the Edmonton Formation or g l a c i a l d e b r i s . The e f f e c t of g l a c i a t i o n i s i n s i g n i f i c a n t . To complete the model, a temperature g r i d must be cons-t r u c t e d . The s i m p l e s t way t o do t h i s i s t o compute the p r e s e n t day geothermal g r a d i e n t and assume t h a t i t , and the s u r f a c e t e m p e r a t u r e , have remained u n i f o r m throughout t i m e . In t h i s i n s t a n c e , i n t e r p r e t a t i o n s by Hacquebard ( 1 9 7 5 ) i n d i -c a t e t h i s not t o be the c a s e . The g r a d i e n t d u r i n g d e p o s i t i o n of the sample c o a l s average 2 . 6 ° C per 1 0 0 meters. W i t h t h i s i n f o r m a t i o n , the temperature g r i d was c o n s t r u c t e d , assuming the temperature g r a d i e n t change i s g r a d u a l . L o p a t i n ' s ( 1 9 7 1 ) method i s based on the time temperature r e l a t i o n s h i p , the temperature dependence of m a t u r i t y b e i n g e x p o n e n t i a l . The t h e o r y i s w e l l p r e s e n t e d i n Waples ( 1 9 8 0 ) . T o t a l m a t u r i t y of a sediment (TTI) i s g i v e n by the sum of m a t u r i t i e s a c q u i r e d i n each temperature i n t e r v a l ; n r/\ax TTI ( ATn )(rn) n rrYirv where n min and n max a r e minimum and maximum t e m p e r a t u r e s , r i s a c o n s t a n t e q u a l t o 2 . 0 , n i s an index s e t by L o p a t i n f o r each temperature i n t e r v a l , and Tn i s the l e n g t h of time spent i n a p a r t i c u l a r temperature i n t e r v a l i . From the.model p r e -s e n t e d , a TTI of 8 . 7 3 was c a l c u l a t e d . L o p a t i n ( 1 9 7 1 ) proposed t h a t d e f i n i t e TTI v a l u e s c o r r e -spond t o the d i f f e r e n t s t a g e s of o i l g e n e r a t i o n i n an analogous manner t o the c o r r e l a t i o n of v i t r i n i t e r e f l e c t a n c e w i t h p e t r o l e u m g e n e r a t i o n . H i s v a l u e s were r e v i s e d by Waples ( 1 9 8 0 ) and a r e p r e s e n t e d i n T a b l e 1-2 and 1 - 3 . Table 1-2 i l -l u s t r a t e s the c o r r e l a t i o n of Ro w i t h TTI as de t e r m i n e d e x p e r i m e n t a l l y from s t u d i e s of 4 0 2 c o a l samples from 31 w o r l d wide r e c o n s t r u c t i o n s . T a b l e 1 - 3 , c o r r e l a t e s TTI and Ro w i t h i m p o r t a n t s t a g e s of o i l g e n e r a t i o n and p r e s e r v a t i o n . In t h i s 200 A g e ( m i l l i o n s o f y e a r s ) Figure 1-6. Geological Model for a p p l i c a t i o n of L o p a t i n ' s Method (1971). 201 Oxrelation of Time-Temperature |nd«x of Maturity (TTI) with Vlulnlte RtflecUnc* ( R 0 ) TTI TTI 0.30 < 1 1.36 180 0.40 < 1 . 1.39 200 0.50 3 1.46 260 0.35 7 1.50 300 0.60 JO 1.62 370 0.65 15 1.75 500 0.70 " 20 1.87 650 0.77 30 2.00 900 0.85 40 2.25 1.600 0.93 36 2.50 2.700 1.00 75 2.75 4.000 1.07 92 3.00 6.000 1.15 110 3.25 9,000 1.19 120 3.50 12.000 1.22 130 4.00 2J.000 1.26 140 4.50 .42.000 1.30 160 5.00 85.000 Table I-11. Correlation of time-temperature index of maturity with v i t r i n i t e reflectance (Waples, 1980). Corulallon of TTI with Important Staftt of OU Generation and Preservation Stage TTI Ro TAI Onset of oil generation 15 0.65 2.65 Peak oil generation 73 1.00 2.9 End of oil feneration 160 1.30 3.2 Upper TTI limit for occurrence of oi l with API gravity <40° -500 1.73 3.6 Upper TTI limit for occurrence of oil with API gravity <509 -1.000 2.0 3.7 Upper TTI limit for occurrence of wet f a» -1,500 2.2 3.7S Last known occurrence of dry l?a» 65.000: 4.1 >4.0 Liquid lulfur in Lone Star Baden 1 (below dry fas limit) 972.000 >3.0 >4.0 Table I-111. Correlation of TTI with important stages of o i l generation and preservation (Waples, 1980). 202 case, a TTI of 8.73 corresponds to an Ro of 0.58%, which i s low in comparison to the values obtained from the data in thi s study. The discrepancy in use of this method is probably due to inaccuracy inherent in the geological model. According to Table 1-2, the maturation of the sediment i s too low for generation of hydrocarbons. The maximum temperature to which the sediments have been exposed using this model is approxi-mately 87° C, which i s within the range obtained using Karweil's (1956) model. Type I (Tissot et a l . , 1958) organic matter must be pre-sent as a source for generating hydrocarbons. The sediments from th i s study, r i c h in v i t r i n i t e grains, were deposited in brackish to continental conditions, unsuitable for the generation of type I organic material. Most of the material may be detritus washed into channels. It may be concluded that the level of organic maturity indicates that the thermal and time conditions are marginal for hydrocarbon production, and the source material i s lacking. Conclusions This study provided information on maximum bu r i a l depths and temperatures for the Calcareous and Glauconitic members of the Mannville Group from Drumheller Alberta. Temperatures ranged from 87° C to 112° C, at maximum bu r i a l depths of 2,438 and 3,048 m (8,000 to 10,000 feet) below sea l e v e l . Applying the method of Lopatin (1969) with a crude geologic model, a similar temperature was determined. The fine sedi-ments of the Calcareous and Glauconitic Members in the Drumheller area have a low potential as hydrocarbon source beds. 203 Appendix II - PALAEONTOLOGY SUMMARY Sixty samples of l i g h t grey to black s i l t s t o n e and shale, and occasional sandstone, were submitted to Shell Canada for palaeontological study. The results are presented in tabular form below. The environment of deposition and age were determined where possible. Basal Quartz samples contained some carbonized plant remains and were lacking in any marine indicators. The lack of diagnostic foraminifera, pollen or spores suggests con-tinental deposition. The study indicates fresh to brackish water deposition for the Calcareous Member sediments. WELL LOCATION DEPTH METRES ENVIR-ONMENT AGE COMMENTS 10-4-26-19W4 1420.3 C. KL(Apt-Alb) 6-6-26-19W4 1405.9 C. KL Abundant pyr i t e 10-12-26-20W4 1454.2 c. KL Fish frag-ments 6-24-30-22W4 1412.4 c. KL (Albian) Grand Rapids eq. A r c e l l i t e s ret iculatus present 7-21-27-09W4 1344.7 C.-T. KL Blairmore Ostracod Mbr equivalent, f ragments of Cytheresis calmontensis present, f i s h and pelecypod fragments. 11-12-27-20W4 1376.4 C. KL Mainly humic matter 11-12-27-20W4 1380.4 C. KL 14 15 27 20W4 1357.6 T. KL Blairmore Ostracod Mbr. 14-15-27-20W4 1358.7 T? KL 8-16-27-20W4 1385.0 Barren 10-22-27-20W4 10-23-27-20W4 7-26-27-20W4 10-27-27-20W4 7-33-27-20W4 7-33-27-20W4 7-2-27-21W4 7-2-27-21W4 7-12-27-21W4 10-22-27-21W4 6-15-27-23W4 6-15-27-23W4 6-15-27-23W4 10-13-28-19W4 7-17-28-20W4 6-11-28-21W4 6-11-28-21W4 1 1 - 12-28-21W4 10-14-28-21W4 7-20-28-21W4 7-23-28-21W4 10 24 28 21W4 1 1-29-28-21W4 1 358, 1 336 1 343 1 347 1 343 1 352, 1412 1421, 1381 1 334 1 538 1 234, 1 393, 1 379, 1 385, 1 384, 1 541 .6 1 5 4 4 . 7 1 4 2 0 . 6 1432 .5 1 4 3 9 . 7 1 4 3 0 . 4 1467 .0 C-F, C? C. C. C. C? C. K L ( A p t - A l b ) K L ( A p t - A l b ) KL K L ( A p t - A l b ) KL KL KL KL KL 204 B a r r e n B a r r e n B a r r e n B a r r e n B a r r e n B a r r e n B a r r e n B a r r e n B a r r e n O s t r a c o d Mbr. , f r e s h w ater. O s t r a c o d Mbr, f r e s h w ater. B a r r e n , p y r i t i z e d p l a n t fragments. B a r r e n B a r r e n E l l e r s l i e or D e v i l l e e q u i v i l e n t , A r c e l l i t e s d i s c o n f o r m i s (Cenomanian-Barremian) and A r c e l l i t e s rugose (Barremian t o A p t i a n ) p r e s e n t . P l a n t fragments. C o a l i f i e d p l a n t and f i s h f r a gments, not d i a g n o s t i c . B a r r e n , abundant c o a l P o s s i b l e E l l e r s l i e eq. , 4-31-28-21W4 6-6-28-22W4 6-6-28-22W4 6-36-29-21W4 10-16-29-20W4 14-25-29-21W4 5-36-29-21W4 10- 19-29-22W4 11- 9-29-22W4 11-9-29-22W4 10-19-29-22W4 6-22-29-23W4 1455.4 1 533.4 1 538.6 1 356.3 1316.4 1 336.8 1 354.2 1464.5 1375.8 1 434.6 4806 1 622.0 C. C.-T. C. C. C.-T. C.-T. KL KL KL KL KL K L ( A p t - A l b ) KL KL KL KL 205 p r o b a b l y Barremian or younger. A r c h e l l i t e s D i s c o n f o r m i s and A r c h e l l i t e s Rugose common t o abundant, p r o b a b l y E l l e r s l i e e q u i v i l e n t . F r e s h w a t e r , O s t r a c o d Zone B a r r e n A r c e l l i t e s D i s c i f o r m i s p r e s e n t C o a l y , b a r r e n of b i o t a . O s t r a c o d e q u i v a l e n t . Prob. Grand R a p i d s e q u i v a l e n t , abundant A r c e l l i t e s r e t i c u t a l u s (range A l b i a n ) and M i n e r i s p o r i t e s v e n u s t u s ( A l b i a n ) p r e s e n t . B a r r e n B l a i rmore O s t r a c o d Mbr. e q u i v a l e n t , C y t h e r s i s c a l m o n t e n s i s p r e s e n t . T r a n s i t i o n a l t o marine environment, no 1 0-24-29-23W4 6-20-29-24W4 6- 20-29-24W4 7- 7-30-22W4 7-7-30-22W4 10-11-30-22W4 6-14-30-22W4 11-34-30-22W4 14-19-30-23W4 6-33-30-23W4 1 1-32-30-23W4 1 1 -32-30-23W4 6-33-30-23W4 1 1-34-30-22W4 14-19-30-23W4 16-21-30-24W4 1518.8 1 586.4 1 592.5 1 449.9 1 450.8 1 429.8 1 430. 1 1 433.4 1572.4 1 599.0 1 541 .3 1 557.2 1 598.0 1433.4 1 572.4 1 663.0 C.-T, C? C.-T, KL KL KL KL K L ( A p t - A l b ) KL KL 206 D i n o f l a g e l l a t e s p r e s e n t , c o a l i f i e d p l a n t remains. B a r r e n B a r r e n B a r r e n Non-diagno-s t i c O s t r a c o d Mbr. , f r e s h water. Non-diagno-s t i c A r c e l l i t e s d i sc i f o r m i s and A r c h e l l i t e s Rugosus p r e s e n t i n g r e a t abundance. B a r r e n O s t r a c o d Mbr. , f r e s h water Background matter i s type seen i n t r a n s i t i o n a l e n v i ronments, but no d i n o f l a g e l l a t e s p r e s e n t , O s t r a c o d Mbr. . Ba r r e n B a r r e n , abundant c o a l . B a r r e n O s t r a c o d Mbr. e q u i v i l e n t , Gomphocythere p r e s u l c a t a v e r y com-mon . .. 207 16-21-30-24W4 1665.0 B a r r e n 208 Appendix III - X-RAY DIFFRACTION ANALYSIS Thirty nine samples, selected on the basis of thin sec-tion examination, stratigraphic position, and lith o l o g y , were were analyzed by X-ray d i f f r a c t i o n to determine the mineralo-gy of the clay f r a c t i o n . Samples were i n i t i a l l y crushed with a mortar and pestle to a fine powder. Powders were dispersed in water, s t i r r e d , and l e f t to s e t t l e for two minutes. Slides were prepared from the suspended material. Disordered k a o l i n i t e predominated in samples of the Drumheller sandstone. Trioctahedral i l l i t e was found in Drumheller, (KBQ) samples, but occurs in greater abundances in the Devi l l e (KDE) Sandstone equivalent k a o l i n i t e and i l l i t e units, with greatest pies. No attempt was unit. Samples from the Glauconitic (KGC) have feldspar and c a l c i t e in addition to Side r i t e was noted in a l l stratigraphic i n t e n s i t i e s in the finer grained sam-made to estimate the r e l a t i v e volumes of each clay in the samples. The results from the analyses are tabulated below. A l l depths are in metres. LOCATION DEPTH (metres) FM. MINERALOGY 14-10-27-20W4 14- 10-27-20w4 15- 13-27-20W4 10-14-27-20W4 10-14-27-20W4 14-15-27-20W4 14-15-27-20W4 14-15-27-20W4 14-15-27-20W4 14-15-27-20W4 14-15-27-20W4 1393.2 1 422.0 1 376.2 1368.5 1384.7 1 363.3 1367.3 1374.3 1 376.2 1379.8 1385.6 KBQ KBQ KDE KBQ KBQ KE k a o l i n i t e , h a l l o y s i t e , alpha quartz, k a o l i n i t e , i l l i t e , alpha quartz, k a o l i n i t e , s i d e r i t e , alpha quartz, k a o l i n i t e , i l l i t e , alpha quartz, k a o l i n i t e , s i d e r i t e , i l l i t e , alpha quartz. k a o l i n i t e , h a l l o y s i t e , alpha quartz. KBQ)t k a o l i n i t e , h a l l o y s i t e , i l l i t e , alpha quartz. KBQ)t k a o l i n i t e , | h a l l o y s i t e , alpha quartz. KBQ)t k a o l i n i t e , h a l l o y s i t e , i l l i t e , alpha quartz. KBQ)t k a o l i n i t e , h a l l o y s i t e , i l l i t e , alpha quartz. KBQ)t k a o l i n i t e , | h a l l o y s i t e , s i d e r i t e , alpha 209 quartz. 1 4-1 5-27- 20W4 1389. 2 KBQ t k a o l i n i t e , h a l l o y s i t e , i l l i t e , alpha quartz. 1 4-1 5-27- 20W4 1 400. 5 KBQ t k a o l i n i t e , alpha quartz. 8- 22- 27- 20W4 1 353. 9 KCZ kaolin i te, ferroan dolomite, alpha quartz. 8- 22- 27- 20W4 1 362. 4 KCZ ka o l i n i t e , i l l i t e , alpha quartz. 8- 22- 27- 20W4 1 372. 2 KBQ k a o l i n i t e , s i d e r i t e , alpha quartz. 8- 22- 27- 20W4 1372. 8 KBQ k a o l i n i t e , alpha quartz. 8- 22- 27- 20W4 1374. 3 KBQ k a o l i n i t e , alpha quartz. 8- 22- 27- 20W4 1375. 2 KBQ kaolin i te, i l l i t e alpha quartz. 8- 22- 27- 20W4 1 376. 7 KBQ ka o l i n i t e , i l l i t e , alpha quartz. 7- 02- 27- 21W4 1382. 2 KGC kaolin i te, i l l i t e , s i d e r i t e , alpha quartz, feldspar 7- 02- 27- 21W4 1429. 5 KBQ kaolini te, i l l i t e , hematite, alpha quartz. 7- 1 7-28- 21W4 1 377. 1 KBQ kaolin i te, h a l l o s i t e , carbonate-apa-t i t e , alpha quartz. 7- 23- 28- 21W4 1479. 8 KBQ ka o l i n i t e , i l l i t e , s i d e r i t e , alpha quartz. 1 1 -02- 28- 21W4 1437. 7 KBQ k a o l i n i t e , i l l i t e , mica, alpha quartz. 1 1 -02- 28- 21W4 1 451 . 7 KBQ k a o l i n i t e , i l l i t e , c a l c i t e , alpha quartz. 1 1 -02- 28- 21W4 1 452. 4 KDE k a o l i n i t e , i l l i t e , s i d e r i t e , alpha quartz. 1 1 -1 2-28- 21W4 1379. 2 KCZ c a l c i t e , montmorillonite?, alpha quartz. •7- 1 7-28- 21W4 1377. 1 KE k a o l i n i t e , alpha quartz. 10- 24- 28- 21W4 1435. 3 KE k a o l i n i t e , alpha quartz. 10- 24- 28- 21W4 1 436. 8 KE k a o l i n i t e , i l l i t e , alpha quartz. 1 1-29- 28- 21W4 1449. 6 KGC k a o l i n i t e , i l l i t e , c a l c i t e alpha quartz. 6- 06- 28- 21W4 1 484. 9 KGC k a o l i n i t e , i l l i t e , muscovite, alpha 10-16-29-20W4 a l p h a q u a r t z , 1 5-36- 29- 21W4 1 0-35- 29- 22W4 10- 14- 29- 2 3W4 1 0-29- 30- 21W4 6-1 4-30- 22W4 1314.6 1 347.8 1 428.6 1 522.2 1400.5 1 457.9 KGC KGC KGC KDE KE KDE 21 q u a r t z . k a o l i n i t e ) i i l l i t e , c a l c i t e , k a o l i n i t e , i l l i t e , a l b i t e , c a l c i t e , s i d e r i t e , a l p h a q u a r t z , k a o l i n i t e , i l l i t e , c a l c i t e , a l p h a q u a r t z . k a o l i n i t e , i l l i t e , a l p h a q u a r t z , k a o l i n i t e , s i d e r i t e , a l p h a q u a r t z , k a o l i n i t e , i l l i t e , s i d e r i t e , a l p h a q u a r t z . 21 1 Appendix IV - THIN SECTION LOCATIONS The locations of a l l thin sections examined are tabu-lated below. Sections were prepared at Shell Canada Labs in Calgary. Sandstones were impregnated with blue resin for visual enhancement of porosity, and stained with a l i z a r i a n red and sodium c o l b a l t i n i t r i t e to aid in c a l c i t e and potas-sium feldspar i d e n t i f i c a t i o n . The formations from which the samples were obtained are l i s t e d in the last column (KDE=Deville Formation, KBQ=Basal Quartz Unit, KCZ=Calcareous Zone, and KGC=Glauconitic Sandstone Equivalent). WELL LOCATION NAME DEPTH metres FM 6-05- 26- 1 9W4 Crz et a l . Hussar 6 -5 1 421 . 0 KBQ 6-05- 26- 1 9W4 Crz. Et a l . Hussar 6-5 1424. 0 KBQ 6-05- 26- 1 9W4 Crz. Et a l . Hussar 6-5 1 427. 5 KBQ 6-05- 1 6-1 9W4 Crz. Et a l . Hussar 6-5 1 431 . 7 KBQ 6-05- 26- 1 9W4 Crz. Et a l . Hussar 6-5 1 433. 0 KBQ 6-05- 26- 1 9W4 Crz. Et a l . Hussar 6-5 1 436. 7 KBQ 6-06- 26- 1 9W4 Sundance et al.Hussar 6-6 1 404. 5 KE 6-06- 26- 1 9W4 Sundance et al.Hussar 6-6 1 409. 5 KE 6-06- 26- 1 9W4 Sundance et al.Hussar 6-6 1412. 0 KE 10- 12- 26- 20W4 CPOG Hussar 10-12 1 450. 2 KE 10- 1 2-26- 20W4 CPOG Hussar 10-12 1 458. 7 KE 10- 12- 26- 20W4 CPOG Hussar 10-12 1 461 . 8 KBQ 11- 18- 27- 1 9W4 Mobil et . a l . Wayne 11-18 1 349. 9 KGC 11- 18- 27- 1 9W4 Mobil et . a l . Wayne 11-18 1 352. 0 KGC 7- 21- 27- 1 9W4 Lata CPOG Wayne 7-2 1 343. 8 KGC 7- 21- 27- 1 9W4 Lata CPOG Wayne 7-2 1 344. 7 KGC 7- 21- 27- 1 9W4 Lata CPOG Wayne 7-2 1346. 9 KGC 7- 21- 27- 1 9W4 Lata CPOG Wayne 7-2 1 350. 8 KGC 1 4-10- 27- 2 0W4 Cairn et a l . Wayne 14-10 1 393. 2 KBQ 14- 1 o-27- 2 0W4 Cairn et a l . Wayne 14-10 1 394. 7 KBQ 14- 10- 27- 2 0W4 Cai rn et a l . Wayne 14-10 1 395. 9 KBQ 14- 10- 27- 20W4 Cairn et a l . Wayne 14-10 1 397. 5 KBQ 14- 10- 27- 20W4 Cai rn et a l . Wayne 14-10 1 398. 1 KBQ 1 4-10- 27- 20W4 Cairn et a l . Wayne 14-10 1402. 8 KBQ 1 4-10- 27- 20W4 Cai rn et a l . Wayne 14-10 1 403. 2 KBQ 1 4-10- 27- 20W4 Cairn et a l . Wayne 14-10 1 404. 7 KBQ 1 4-10- 27- 20W4 Cairn et a l . Wayne 14-10 1405. 0 KBQ 1 4-10- 27- 20W4 Cai rn et a l . Wayne 14-10 1406. 0 KBQ 1 4-10- 27- 20W4 Cai rn et a l . Wayne 14-10 1 408. 8 KBQ 14- 10- 27- 20W4 Cairn et a l . Wayne 1 4-10 1 409. 0 KBQ 14- 10- 27- 20W4 Cai rn et a l . Wayne 1 4-10 1412. 0 KBQ 1 1-1 2-27- 2 0W4 Grt.Pins .Tri .Soc.CPPv Wayne! 1-12 1 377. 5 KE 1 5-1 3-27- 20W4 Grt.Pins . Soc . Wayne 15-13 1 369. 6 KBQ 1 5-1 3-27- 20W4 Grt.Pins . Soc . Wayne 15-13 1374. 1 KBQ 1 5-1 3-27- 20W4 Grt.Pins . Soc . Wayne 15-13 1376. 1 KDE 10- 1 4-27- 20W4 Mobil et a l . Wayne 1 0-14 1 368. 5 KBQ 10- 1 4-27- 20W4 Mobil et a l . Wayne 10-14 1370. 0 KBQ 10- 1 4-27- 20W4 Mobil et a l . Wayne 10-14 1 370. 6 21 ; KBQ 10- 1 4-27- 20W4 Mobil et a l . Wayne 10-14 1 381 . 9 KBQ 1 o-1 4-27- 20W4 Mobil et. Al Wayne 10-14 1 384. 7 KBQ 2- 1 5-27- 20W4 Cairn et a l . Wayne 2-15 1407 KBQ 1 4-15- 27- 20W4 Highfield et a l . Wayne 14-1 5 1 363. 3 KCZ 1 4-15- 27- 20W4 Highfield et a l . Wayne 14-1 5 1 367. 3 KBQ 1 4-15- 27- 20W4 Highfield et a l . Wayne 14-1 5 1 373. 1 KBQ 1 4-1 5-27- 20W4 Highfield et a l . Wayne 14-1 5 1 374. 3 KBQ 1 4-25- 27- 20W4 Highfield et a l . Wayne 14-1 5 1376. 1 KBQ 1 4-25- 27- 20W4 Highfield et a l . Wayne 14-1 5 1 377. 0 KBQ 1 4-15- 27- 20W4 Highfield et a l . Wayne 14-1 5 1379. 8 KBQ 1 4-1 5-27- 20W4 Highfield et a l . Wayne 14-1 5 1385. 6 KBQ 1 4-1 5-27- 20W4 Highfield et a l . Wayne 14-1 5 1389. 2 KBQ 1 4-1 5-27- 20W4 Highfield et a l . Wayne 14- 1 5 1 400. 5 KBQ 8-1 6-27- 20W4 Cairn et a l . Wayne 8-16 1388. 0 KBQ 8-16- 27- 20W4 Cairn et. Al Wayne 8-16 1 392. 0 KBQ 8-1 6-27- 20W4 Cairn et a l . Wayne 8-16 1406. 0 KBQ 6-22- 27- 20W4 Grt.Plns. T r i .Soc.CPR Wayne 6-22 1 362. 4 KBQ 6-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 6-22 1 365. 1 KBQ 6-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 6-22 1 369. 4 KBQ 6-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 6-22 1377. 6 KBQ 6-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 6-22 1 392. 8 KBQ 8-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 6-22 1 356. 4 KBQ 8-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 8-22 1 372. 2 KBQ 8-22- 27- 20W4 Grt.Pins. Tr i .Soc.CPR Wayne 8-22 1372. 8 KBQ 8-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 8-22 1 374. 3 KBQ 8-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 8-22 1375. 3 KBQ 8-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Wayne 8-22 1 376. 7 KBQ 10- 22- 27- 20W4 Grt.Pins. T r i .Soc.CPR WaynelO-22 1 375. 8 KBQ 1 2-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Waynel2-22 1 366. 7 KBQ 1 2-22- 27- 20W4 Grt.Pins. T r i . Soc.CPR Waynel2-22 1 372. 5 KBQ 1 2-22- 27- 20W4 Grt.Pins. T r i .Soc.CPR Waynes-22 1 322. 2 KGC 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1322. 2 KGC 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1 333. 1 KCZ 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1 350. 8 KE 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1363. 6 KE 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1 364. 5 KBQ 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1 369. 4 KBQ 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1374. 0 KBQ 10- 23- 27- 20W4 Mobil et a l . Wayne 1 0-23 1378. 9 KBQ 7-26- 27- 20W4 Mobil et a l . Wayne 7-26 1312. 7 KGC 7-26- 27- 20W4 Mobil et a l . Wayne 7-26 1318. 5 KGC 7-26- 27- 20W4 Mobil et a l . Wayne 7-26 1322. 2 KGC 7-26- 27- 20W4 Mobil et a l . Wayne 7-26 1327. 7 KGC 7-26- 27- 20W4 Mobil et a l . Wayne 7-26 1343. 0 KE 7-26- 27- 20W4 Mobil et a l . Wayne 7-26 1348. 1 KBQ 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1313. 6 KGC 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1321 . 6 KGC 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1 328 0 KGC 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1332. 8 KGC 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1338. 0 KGC 10- 27- 27- 20W4 Mobil et a l . Wayne 10-27 1338. 9 KCZ 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1356. 6 KBQ 10- 27- 27- 20W4 Mobil et a l . Wayne 1 0-27 1 362. 4 KBQ 10- 28- 27- 20W4 Zapata e t a l . Wayne 10 -28 1 349. 3 21 KBQ 10- 28- 27- 20W4 Zapata et a l . Wayne 10 -28 1 354. 5 KBQ 7-33- 27- 2 0W4 TGT Wayne 7-33 1355. 4 KBQ 7-02- 27- 21W4 PCP e t a l . Hussar 7-2 1 392. 0 KGC 7-02- 27- 21W4 PCP e t . A l Hussar 7-2 1 396. 2 KGC 7-02- 27- 21W4 PCP e t a l . Hussar 7-2 1 397. 5 KGC 7-02- 27- 21W4 PCP e t a l . Hussar 7-2 1 406. 6 KCZ 7-02- 27- 21W4 PCP et a l . Hussar 7-2 1429. 5 KBQ 7-02- 27- 21W4 PCP et a l . Hussar 7-2 1432. 8 KBQ 7-02- 27- 2TW4 PCP et a l . Hussar 7-2 1 436. 2 KBQ 7-02- 27- 21W4 PCP et a l . Hussar 7-2 1 437 . 7 KBQ 7-02- 27- 2 1W4 PCP et a l . Hussar 7-2 1 439. 9 KDE 7- 1 2-27- 2 1W4 P e n z l CPOG Hussar 7-12 1378. 3 KGC 7- 1 2-27- 2 1W4 P e n z l CPOG Hussar 7-12 1 380. 7 KGC 7- 1 2-27- 2 1W4 P e n z l CPOG Hussar 7-12 1 382. 2 KGC 7- 1 2-27- 21W4 P e n z l CPOG Hussar 7-12 1 386. 8 KGC 7- 1 2-27- 21W4 P e n z l CPOG Hussar 7-12 1 388. 4 KGC 1 o-22- 27- 2 1W4 CPOG Rosebud 10-22 1 338. 3 KBQ 10- 22- 27- 2 1W4 CPOG Rosebud 10-22 1 344. 1 KBQ 10- 22- 27- 21W4 CPOG Rosebud 10-22 1 345. 9 KBQ 10- 22- 27- 21W4 CPOG Rosebud 10-22 1 358. 4 KBQ 10- 22- 27- 2 1W4 CPOG Rosebud 10-22 1 361 . 2 KBQ 1 o-22- 27- 21W4 CPOG Rosebud 10-22 1 371 . 2 KBQ 1 o- 1 3-28- 1 9W4 Pex. Drum 10-13 1234. 0 KBQ 6-09- 28- 20W4 TGT Rosedale 6-9 1 341 . 4 KGC 6-09- 28- 20W4 TGT Rosedale 6-9 1 344. 1 KGC 6-09- 28- 20W4 TGT Rosedale 6-9 1 344. 7 KGC 6-09- 28- 20W4 TGT Rosedale 6-9 1 348. 1 KGC 6-09- 28- 20W4 TGT Rosedale 6-9 1 349. 0 KGC 6-09- 28- 20W4 TGT Rosedale 6-9 1 350. 2 KGC 7- 17- 28- 20W4 TGT Rosedale 7-17 1 375. 2 KBQ 7- 1 7-28- 20W4 TGT Rosedale 7-17 1 376. 1 KBQ 7- 1 7-28- 20W4 TGT Rosedale 7-17 1377. 0 KBQ 7- 1 7-28- 20W4 TGT Rosedlae 7-17 1378. 6 KBQ 7- 1 7-28- 20W4 TGT Rosedale 7-17 1 386. 2 KBQ 7- 1 7-28- 20W4 TGT Rosedale 7-17 1 392. 3 KBQ 7- 1 7-28- 20W4 TGT Rosedale 7-17 1 396. 9 KBQ 10- 36- 28- 20W4 M o b i l et a l . Drum. 10- 36 1 190. 0 KGC 10- 36- 28- 20W4 M o b i l et a l . Drum. 10- 36 1 195. 4 KGC 1 1-02- 28- 21W4 M o b i l NW. Wayne 11 -2 1430. 0 KBQ 1 1-02- 28- 21W4 M o b i l NW. Wayne 11 -2 1440. 6 KBQ 1 1 -02- 28- 21W4 Mobi 1 NW. Wayne 11 -2 1442. 0 KBQ 1 1 -02- 28- 21W4 Mobi 1 NW. Wayne 11 -2 1447. 1 KDE 1 1-02- 28- 21W4 Mobi 1 NW. Wayne 11 -2 1447. 8 KDE 1 1-02- 28- 21W4 Mobi 1 NW. Wayne 11 -2 1 451 . 7 KDE 1 1 -02- 28- 21W4 Mobi 1 NW. Wayne 11 -2 1 452. 8 KDE 1 1-02- 28- 21W4 M o b i l NW. Wayne 11 -2 1452. 8 KDE 1 1 -02- 28- 21W4 Mobi 1 NW. Wayne 11 -2 1455. 4 M 6- 1 1 -28- 21W4 M o b i l NW. Wayne 6- 1 1 1 391 . 1 KGC 6- 1 1-28- 21W4 M o b i l NW. Wayne 6- 1 1 1392. 6 KGC 6-1 1-28- 21W4 M o b i l NW. Wayne 6- 1 1 1420. 6 KGC 1 1-12- 28- 21W4 CPOG Wayne 11-12 1383. 1 KBQ 1 1 -1 2-28- 21W4 CPOG Wayne 11-12 1385. 9 KBQ 1 1-1 2-28- 21W4 CPOG Wayne 11-12 1389. 7 KBQ 3 11 -12-28-21W4 CPOG Wayne 11-12 1399. 3 9-14-28-21W4 CPOG Wayne 9-14 1 431 . 9 9-14-28-21W4 CPOG Wayne 9-14 1 434. 0 9-14-28-21W4 CPOG Wayne 9-14 1 435. 6 9-14-28-21W4 CPOG Wayne 9-14 1 436. 5 9-14-28-21W4 CPOG Wayne 9-14 1 437. 2 9-14-28-21W4 CPOG Wayne 9-14 1 438. 6 9-14-28-21W4 CPOG Wayne 9-14 1 441 . 1 9-14-28-21W4 CPOG Wayne 9-14 1441. 7 9-14-28-21W4 CPOG Wayne 9-14 1 443. 9 9-14-28-21W4 CPOG Wayne 9-14 1 444 . 1 9-14-28-21W4 CPOG Wayne 9-14 1 445. 6 9-14-28-21W4 CPOG Wayne 9-14 1447. 1 10-14-28-21W4 CPOG Wayne 10-14 1418. 5 10-14-28-21W4 CPOG Wayne 10-14 1419. 1 10-14-28-21W4 CPOG Wayne 10-14 1 424. 9 7-20-28-21W4 CPOG Cat ine 7-20 1420. 3 7-20-28-21W4 CPOG Catine 7-20 1 425. 3 7-20-28-21W4 CPOG Catine 7-20 1 430. 4 7-20-28-21W4 CPOG Catine 7-20 1 430. 4 7-23-28-21W4 CPOG Wayne 7-23 1412. 7 7-23-28-21W4 CPOG Wayne 7-23 1 432. 5 7-23-28-21W4 CPOG Wayne 7-23 1 448. 5 7-23-28-21W4 CPOG Wayne 7-23 1 448. 5 7-23-28-21W4 CPOG Wayne 7-23 1 449. 1 7-23-28-21W4 CPOG Wayne 7-23 1 453. 2 7-23-28-21W4 CPOG Wayne 7-23 1 454. 5 7-23-28-21W4 CPOG Wayne 7-23 1 456. 0 7-23-28-21W4 CPOG Wayne 7-23 1 458. 0 7-23-28-21W4 CPOG Wayne 7-23 1 459. 0 7-23-28-21W4 CPOG Wayne 7-23 1 459. 5 7-23-28-21W4 CPOG Wayne 7-23 1 461 . 6 7-23-28-21W4 CPOG Wayne 7-23 1468. 2 7-23-28-21W4 CPOG Wayne 7-23 1472. 1 7-23-28-21W4 CPOG Wayne 7-23 1 479. 8 12-13-29-20W4 PanAlta Empire Drum 12 -13 1239. 0 1 2-1 3-29-2.0W4 PanAlta Empire Drum 12 -13 1245. 4 12-13-29-20W4 PanAta Empire Drum 12- 1 3 1248. 2 6-27-29-20W4 Garvey Dome Murrson 1303. 9 6-27-29-20W4 Garvey Dome Murrson 1 306. 0 6-27-29-20W4 Garvey Dome Murrson 1 309. 4 14-25-29-21W4 Superior et a l . Drum. 1 4 -25 1 336. 8 14-25-29-21W4 Superior et a l . Drum. 14 -25 1357. 2 14-25-29-21W4 Superior et a l . Drum. 1 4 -25 1 395. 6 5-36-29-21W4 Superior et a l . Drum 5- 36 1 345. 6 5-36-29-21W4 Superior et a l . Drum 5- 36 1 347. 8 5-36-29-21W4 Superior et a l . Drum 5- 36 1 347. 8 5-36-29-21W4 Superior et a l . Drum 5- 36 1362. 1 5-36-29-21W4 Superior et a l . Drum 5- 36 1 364. 5 6-36-29-21W4 Superior et . Al Drum. 6-36 1 342. 6 6-36-29-21W4 Superior et . Al Drum. 6-36 1374. 6 6-36-29-21W4 Superior et . Al Drum. 6-36 1 381 . 0 6-36-29-21W4 Superior et . Al Drum. 6-36 1 382. 2 10-08-29-22W4 CWNG Carbon 10-8 1501 21 10- 08- 29- 22W4 CWNG Carbon 10-8 1 507 21 KBQ 10- 08- 29- 22W4 CWNG Carbon 10-8 1511 KBQ 10- 08- 29- 22W4 CWNG Carbon 10-8 1516 KBQ 1 o-08- 29- 22W4 CWNG Carbon 10-8 1 520 KBQ 10- 08- 29- 22W4 CWNG Carbon 10-8 1525 KBQ 10- 08- 29- 2 2W4 CWNG Carbon 10-8 1 529 KBQ 10- 08- 29- 22W4 CWNG Carbon 10-8 1 535 KBQ 11 -09- 29- 22W4 Ca l v a n e t a l . Carbon 1 1-9 1 435. 9 KGC 11 -09- 29- 22W4 Ca l v a n et a l . Carbon 1 1-9 1 440. 7 KGC 11 -09- 29- 22W4 Cal v a n et a l . Carbon 11-9 1 442. 6 KGC 11 -09- 29- 22W4 Ca l v a n et a l . Carbon 1 1-9 1 446. 5 KGC 7- 1 7-29- 22W4 S h e l l Carbon 37-17 1388. 9 KGC 7- 1 7-29- 22W4 S h e l l Carbon 37-17 1 451 . 7 KGC 7- 29- 29- 22W4 S h e l l Carbon 07-29 1 449. 3 KGC 7- 29- 29- 22W4 S h e l l Carbon 07-29 1460. 9 KGC 10- 35- 29- 2 2W4 Sage Hesketh 10-35 1419. 6 KGC 10- 35- 29- 2 2W4 Sage Hesketh 10-35 1 434. 9 KGC 10- 24- 29- 2 3W4 CWNG Carbon 10-24 1 525. 2 KDE 6-32- 29- 23W4 Andex Bumper GPine 6-32 1 626. 5 KBQ 10- 29- 30- 21W4 B.A. Hesketh 10-29 1 403. 6 KBQ 10- 1 1 -30- 22W4 B.A. Et a l . Huber Wesketh 6-14 1 427. 3 KBQ 6- 1 4-30- 22W4 B.A. Hesketh e t a l . 6 -14 1 426. 1 KCZ 6- 1 4-30- 2 2W4 B.A. Hesketh e t a l . 6 -14 1 444. 0 KBQ 6- 1 4-30- 22W4 B.A. Hesketh e t a l . 6 -14 1 454. 5 KBQ 6- 1 4-30- 22W4 B.A. Hesketh e t a l . 6 -14 1 459. 0 KDE 1 1 -21- 30- 22W4 B.A. E t . a l . Ghost P i n e 11-21 1418. 8 KGC 6-24- 30- 22W4 B.A. Et a l . Hesketh 6 -24 1 405. 7 KGC 6- 24- 30- 22W4 B.A. Et a l . Hesketh 6 -24 1 409. 3 KGC 6- 24- 30- 22W4 B.A. Et a l . Hesketh 6 -24 1411. 5 KBQ 6-24- 30- 22W4 B.A. Et a l . Hesketh 6 -24 1414. 9 KBQ 6- 33- 30- 23W4 Andex e t a l . T w i n n i n g 1 598. 5 KBQ 6-33- 30- 2 3W4 Andex e t a l . T w i n n i n g 1 600. 3 KBQ 216 Appendix V - S.E.M. SAMPLE LOCATIONS El e v e n samples of D r u m h e l l e r Sandstone were s e l e c t e d on the b a s i s of t h i n s e c t i o n p e t r o l o g y , hand specimen examina-t i o n , and s t a t i g r a p h i c l o c a t i o n , f o r SEM-EDS s t u d y . F r a c t u r e d s u r f a c e s were examined i n each case , a n n o t a t e d w i t h t h i n s e c t i o n f o r e i g h t samples. A l l were c o a t e d w i t h c a r b o n . L o c a t i o n s and c h a r a c t e r i s t i c s a r e t a b u l a t e d below. W e l l Depth C h a r a c t e r i s t i c s 14- 1 0-27- 20W4 1 393. 2 Fr a m b o i d a l p y r i t e , low p o r o s i t y , pore f i l l i n g kao-l i n i t e . 1 4-1 0-27- 20W4 1 394. 2 R e l i c t c a r b o n a t e cement i n po r e s , good q u a r t z o v e r -growths . 1 4-1 0-27- 20W4 1406. 0 Abundent q u a r t z o v e r g r o w t h . 1 4-1 5-27- 20W4 1 373. 1 Some s i l i c a d i a g e n e s i s , s i d e r i t e s p h e r u l i t e s . 6-22- 27- 20W4 1 377. 7 Hematite i n m a t r i x , some s i l i c a d i a g e n e s i s . 1 0-23- 27- 20W4* 1 484. 2 A u t h i g e n i c k a o l i n i t e pore f i l l , and s i d e r i t e . 10- 23- 27- 20W4* 1 485. 2 Fr a m b o i d a l p y r i t e , s i l i c a d i a g e n e s i s. 7- 26- 27- 20W4* 1451. 0 Good q u a r t z o v e r g r o w t h , i n t e r g r a n u l a r p o r o s i t y . 7- 1 7-28- 21W4 1482. 2 B a r i t e cement, r a r e o v e r -growths, some s i d e r i t e cement. 1 1-02- 28- 21W4 1440. 6 P r e s s u r e s o l u t i o n and q u a r t z o v e r g r o w t h . 9- 1 4-28- 21W4 1437. 4 W e l l s o r t e d , s i l i c a o v e r -growths, t r a c e c a r b o n a t e cement. * f r a c t u r e d s u r f a c e o n l y Appendix VI - SYMBOLS The symbols used i n the l i t h o l o g i c p r o f i l e s a r e d e f i n e d i n the t a b l e below: m -rr LITHOLOGIES S h a l e (sh) S i l t s t o n e ( s l t s t n ) Sandstone ( s s ) B r e c c i a ( b r e c ) L i m e s t o n e ( I s ) A r g i l l a c e o u s L i m e s t o n e ( a r g I s ) C o a l (C) WELL SYMBOLS O i l Zone Gas Zone STRUCTURES, ETC. / C r o s s b e d d i n g B i o t u r b a t i o n R i p p l e s Wavy Bedding -~ ^ ^ L e n t i c u l a r Bedding -t M i c r o f a u l t s A* Root i n g C o a l i f i e d Wood P l a n t Remains A A A C h e r t Nodules <=>Oo S i l t s t o n e C l a s t s r\r\r\r\r\ S h e l l D e b r i s P P y r i t e rr\ Maroon C o l o u r a t i o n _ i 1_ C a l c a r e o u s Cement Appendix V I I - PERCENT RELIEF DEFINITION When 'Percent R e l i e f i s s p e c i f i e d on a 3-D p l o t the r e l i e f i s the maximum Z v a l u e as a p e r c e n t of the maximum or Y dimensi o n of the map. A l l o t h e r Z v a l u e s a r e i n t e r p o -l a t e d between the maximum r e l i e f and z e r o . For example, i f X max = 15cm and Y max = = 1 0cm then X = 15cm i s the maximum dimension of the map and i f , P e r c e n t R e l i e f = 25% then Max R e l i e f = 15cm x 25% = 3.75cm and i f , Z max = 400m t h e n , Z max R e l i e f = 3.75cm 219 Appendix VIII - MAPS A series of maps (9) were constructed in t h i s study. In order, they are; Map 1: Mississippian Subcropping Formations Map 2: Mississippian Structure Map 3: Mississippian Residuals Map 4: Mannville Isopach Map 5: Lower Mannville Isopach Map 6: De v i l l e Formation Isopach Map 7: Basal Quartz (Drumheller) Unit Isopach Map 8: Calcareous Member Isopach Map 9: Lithofacies of the Basal Quartz (Drumheller) A l l are at a scale of 1:96,000. The gr i d l i n e s correspond to the regional survey g r i d . Townships, ranges, and legal subdi-visions are marked (each legal subdivision is one square mile in area). Maps are f i l e d separately. See p.xiv for l i s t i n g . MAPS WHICH ARE LISTED ON P . x i v FOR LISTING ON PAGES 220-228 WILL APPEAR AT THE END OF THESES. 229 Appendix IX - CROSS SECTIONS Fo u r t e e n c r o s s - s e c t i o n s were c o n s t r u c t e d i n t h i s s t u d y . The major s e c t i o n s a r e o r i e n t e d e i t h e r i n the d i r e c t i o n of r e g i o n a l d i p or p e r p e n d i c u l a r t o i t . Three of the s e c t i o n s are not o r i e n t e d i n e i t h e r d i r e c t i o n , h a v i n g been used t o t i e o t h e r s e c t i o n s t o g e t h e r or i n v e s t i g a t e s p e c i f i c u n i t s . E l e v e n of the f o u r t e e n s e c t i o n s a re p r e s e n t e d i n t h i s a p p e n d i x . C o r r e l a t i o n of u n i t s i n the t h r e e s e c t i o n s o m i t t e d c o u l d not be made w i t h a s u i t a b l e degree of c o n f i d e n c e due t o the poor q u a l i t y of the g e o p h y s i c a l l o g s and l a r g e s p a c i n g between w e l l s . In the f o l l o w i n g t e x t , the im p o r t a n t c h a r a c t e r i s t i c s of each s e c t i o n a r e p r e s e n t e d . S e c t i o n 1 (A-A'), o r i e n t e d n o r t h e a s t - s o u t h w e s t , e x h i b i t s s e v e r a l i n t e r e s t i n g f e a t u r e s . The D r u m h e l l e r ( B a s a l Q u a r t z ) u n i t i s absent i n the southwest and a f a c i e s change i n the u n i t can be noted. To the e a s t , the l o g c h a r a c t e r d e s c r i b e s b l o c k y sand c h a n n e l s , i n the m i d d l e of the s e c t i o n , c o a r -s e n i n g upward sequences are noted ( 7-34-29-22 W4), and t o the west, the u n i t i s absent. A t h i n tongue of D r u m h e l l e r sandstone appears t o extend i n t o the C a l c a r e o u s Member. The C a l c a r e o u s Member t h i n s toward the e a s t . T h i s r e l a t i o n s h i p may suggest d e p o s i t i o n of the C a l c a r e o u s Member and D r u m h e l l e r u n i t i n p a r t contemporaneously. W i t h i n the Upper M a n n v i l l e , two sand f i l l e d c h a n n e l s a re noted (10-19-29-22 W4 and 6-14-30-22 W4). The l o c a t i o n of the sand b o d i e s appears not t o be r e l a t e d t o the c o n f i g u r a t i o n of the u n d e r l y i n g M i s s i s s i p p i a n s u r f a c e . T h i s s u g g e s t s t h a t l o c a l l y , the r e l i e f on the u n c o n f o r m i t y had been f i l l e d by the time d e p o s i t i o n of the G l a u c o n i t i c sandstone e q u i v a l e n t o c c u r e d . S e c t i o n 2 (B-B') t r e n d s n o r t h e a s t - s o u t h w e s t , p a r a l l e l t o the s t r u c t u r a l d i p of the r e g i o n . The D e v i l l e F o r m a t i o n i s f i n e r g r a i n e d and t h i n n e r over p a l e o h i g h s . The D r u m h e l l e r ( B a s a l Q u a r t z ) u n i t i s t h i c k e s t i n p a l e o l o w s . In w e l l s 6-30-26-20 W4 and 6-11-27-20W4, a sandstone, 6 and 16 metres t h i c k r e s p e c t i v e l l y , i s found s t r a t i g r a p h i c a l l y under the D e v i l l e s h a l e s and s i l t s . The l i t h o l o g y of t h i s sand i s unknown. I f s i m i l a r t o the D r u m h e l l e r sandstones above, i t i n d i c a t e s com-temporaneous d e p o s i t i o n of the two u n i t s . I t c o u l d a l s o be an o u t l i e r of J u r a s s i c sandstone or a c l e a n member of the D e v i l l e F o r m a t i o n . The t h i c k n e s s of the C a l c a r e o u s Member de c r e a s e s toward the e a s t . In s e c t i o n 3 ( C - C ) , the D e v i l l e F o r m a t i o n , D r u m h e l l e r U n i t , and C a l c a r e o u s Member a r e p r e s e n t i n a l l w e l l s . G r e a t e s t t h i c k n e s s e s of the D e v i l l e and D r u m h e l l e r u n i t s a r e i n p a l e o l o w s , i l l u s t r a t i n g the f i l l n a t u r e of t h e s e s e d i -ments. The c h a r a c t e r of the D r u m h e l l e r sandstone changes from b l o c k y , t h i c k sandstone sequences i n the s o u t h e a s t , t o b l o c k y and f i n i n g upward sequences, w i t h an i n c r e a s e d c o n t e n t of f i n e s , i n the west. The E l l e r s l i e F o r m a t i o n i s p r e s e n t i n a 230 few wells to the northwest. A well defined, extensive lime-stone unit i s noted in the top portion of the Calcareous Member. The Deville Formation is absent on many paleohighs in Section 4 (D-D'). The Upper Mannville sands, equivalent to the Glauconitic sandstones of southeastern Alberta, f i l l scours cut into Lower Mannville Calcareous Zone sediment, and in the northwest, exhibit a blocky channel p r o f i l e . Section 5 (E-E'), located in the western section of the study area, shows a dramatic change in thickness of the Calcareous Member from west to east. In the west, the unit, resting d i r e c t l y on sediment of the Dev i l l e Formation, has a thickness of over 40 metres. To the east, the unit thins to 5 metres, where i t rests upon Drumheller sandstones. The Drumheller sandstone changes from a thick blocky sandstone in the east, through a zone of coarsening upward sands, to a fine s i l t toward the west. These c h a r a c t e r i s t i c s are int e r -preted to r e f l e c t , in part, contemporaneous deposition of the two units, and related facies changes. The D e v i l l e Formation is finer grained over paleohighs. The Drumheller (Basal Quartz) unit i s absent throughout section 6 (F-F'). This section i l l u s t r a t e s the widespread co r r e l a t i o n of individual limestones, the coarsening upward c y c l i c a l deposition of units, and the d i s t r i b u t i o n of Calcareous Member sands. Section 7 (G-G'), i s located south of the study area, i l l u s t r a t i n g the f i l l nature of the Drumheller (Basal Quartz) unit. A shale bed i s present throughout the Upper Mannville Glauconitic Sandstone equivalent, and can be observed in sev-era l other sections. In section 8 (H-H'), D e v i l l e sediments are absent in 11-2-28-21 W4. This may r e f l e c t post-depositional or penecontem-poraneous erosion of the unit related to deposition of the Drumheller sands. The valley f i l l nature of the Drumheller sands i s again apparent. A sharp d e f l e c t i o n of the Gamma Ray curve commonly marks the top of the Drumheller sandstone, and in core, corresponds to a zone of sandstone which has been cemented with p y r i t e . The E l l e r s l i e Formation i s present in two northern wells. Good correlation of Calcareous Zone lime-stones i s common. In section 9 ( J - J ' ) , Drumheller (Basal Quartz) sand-stones are absent in the northeast and thickest in the southwest. This is opposite to the other sections described thus far. In this case we see the eastern margin of a con-tinuation of the Drumheller sand sheet and can define the western margin of the major Calcareous Member depositional basin. The top of the Drumheller sandstone i s commonly marked by a strong deflection on the Gamma Ray log. Small sand 231 b o d i e s w i t h i n the C a l c a r e o u s Member e x t e n d i n g from the edge of the D r u m h e l l e r sand s h e e t , appear t o c o a r s e n upward i n g r a i n s i z e , and may be i n t e r p r e t e d a s m a l l d e l t a s . The D e v i l l e F o r m a t i o n p i n c h e s out a t a h i g h i n the n o r t h e a s t of s e c t i o n 10 ( K - K ' ) . The E l l e r s l i e F o r m a t i o n i s p r e s e n t i n a low i n the southwest. The t h i c k n e s s of the C a l c a r e o u s Member d e c r e s e s s l i g h t l y towards the e a s t . A Carbon Sandstone c h a n n e l i s p r e s e n t i n the s e c t i o n . R e l a t i o n s h i p s between the C a l c a r e o u s Member and the Carbon sandstone i n w e l l s 6-14-30-19 W4 and 10-18-30-18 W4 suggest d e p o s i t i o n , i n p a r t , of the two u n i t s contemporaneously. In the l a s t s e c t i o n , s e c t i o n 11 ( L - L ' ) , the D r u m h e l l e r ( B a s a l Q u a r t z ) sandstone i s absent i n the m i d d l e of the sec-t i o n where the C a l c a r e o u s Member a t t a i n s i t s g r e a t e s t t h i c k n e s s . F a c i e s changes are apparent on both the n o r t h -western and s o u t h e a s t e r n margins of the D r u m h e l l e r sandstone. 232 - 242 Cross sections are f i l e d separately. See p.xv for l i s t i n g .
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Geological Sciences
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Deposition of the cretaceous lower mannville group, Drumheller area, Alberta
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