Fluid Compartmentalization of Devonian and Mississippian Dolostones, Western Canada Sedimentary Basin: Evidence from Fracture Mineralization

University of Windsor Scholarship at UWindsor

Electronic Theses and Dissertations Theses, Dissertations, and Major Papers

2016

Carole Mrad University of Windsor

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Recommended Citation Mrad, Carole, "Fluid Compartmentalization of Devonian and Mississippian Dolostones, Western Canada Sedimentary Basin: Evidence from Fracture Mineralization" (2016). Electronic Theses and Dissertations. 5752. https://scholar.uwindsor.ca/etd/5752

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By Carole Mrad

A Thesis Submitted to the Faculty of Graduate Studies through the Department of Earth and Environmental Sciences in Partial Fulfillment of the Requirements for the Degree of Master of Science at the University of Windsor

Fluid Compartmentalization of Devonian and Mississippian Dolostones, Western Canada Sedimentary Basin; Evidence from Fracture Mineralization

Carole Mrad

APPROVED BY:

______Dr. Jan Ciborowski, External Examiner Department of Biological Sciences

______Dr. Jianwen Yang, Internal Examiner Department of Earth and Enviironmental Sciences

______Dr. Ihsan Al-Aasm Department of Earth and Enviironmental Sciences

May 27, 2016

Author’s Declaration of Originality

I hereby certify that I am the sole author of this thesis and that no part of this thesis has been published or submitted for publication.

I certify that, to the best of my knowledge, my thesis does not infringe upon anyone’s copyright nor violate any proprietary rights and that any ideas, techniques, quotations, or any other material from the work of other people included in my thesis, published or otherwise, are fully acknowledged in accordance with the standard referencing practices. Furthermore, to the extent that I have included copyrighted material that surpasses the bounds of fair dealing within the meaning of the Canada Copyright Act, I certify that I have obtained a written permission from the copyright owner(s) to include such material(s) in my thesis and have included copies of such copyright clearances to my appendix.

I declare that this is a true copy of my thesis, including any final revisions, as approved by my thesis committee and the Graduate Studies office, and that this thesis has not been submitted for a higher degree to any other University or Institution.

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Abstract

Integrated petrographic, geochemical and fluid inclusion study of fracture mineralization in

Mississippian and Devonian dolostones extending from Alberta to British Columbia, Canada aims at quantifying the type and nature of fluids that precipitated diagenetic minerals and whether these fluids represent a single or multiple events. Fracture-filling saddle dolomite and calcite from three

Devonian and two Mississippian carbonate successions were investigated in this study. The

Devonian formations include Slave Point and Duvernay formations and the Mississippian Upper

Debolt and Turner Valley formations.

Isotopic evidence from dolomite cement indicate the presence of a hydrothermal fluid source. The

Mississippian saddle dolomite is characterized by less depleted δ18O isotopic values, less radiogenic 87Sr/86Sr isotopic ratios and lower homogenization temperatures and salinity values of fluid inclusions compared to the Devonian saddle dolomite. These results suggest that possibly two hydrothermal pulses related to early (Antler) and late (Laramide) tectonic events affected the

Western Canada Sedimentary Basin.

Dedication

This thesis is dedicated to my aunts, Hana and May Bader, and my uncle, Dr. Eyad Meibar.

Without their infinite support, encouragement and love I would not be where I am today.

Acknowledgements

I would like to sincerely thank my supervisor Dr. Ihsan Al-Aasm for his constructive advice, guidance and continuous support during the past two years. I appreciate the useful suggestions and feedback given by my thesis readers Dr. Jianwen Yang and Dr. Jan Ciborowski during the research proposal and thesis defense. I would like to thank Ms. Carina Luo at the Leddy library for her help with the ArcGIS spatial variability maps.

I am also thankful to all the faculty members and staff at the Department of Earth and

Environmental Sciences, University of Windsor, especially to Dr. Ali Polat, Dr. Iain Samson, Dr.

Joel Gagnon, Melissa Price, Margaret Mayer, Dr. Alice Grgicak-Mannion, Dr. Denis Tetreault and

Dr. Maria Cioppa. I would like to thank my graduate peers as well for their support and wish them the best in their research areas and career.

Finally, I would like to thank my parents for their encouragement and support throughout my academic years.

Table of Contents

Author’s Declaration of Originality ...... iii Abstract ...... iv Dedication...... v Acknowledgements ...... vi List of Figures ...... ix List of Tables ...... xiii Chapter 1 ...... 1 Introduction ...... 1 1.1 Purpose of Study: ...... 2 2.2 Previous Studies ...... 3 Chapter 2 ...... 11 Geologic and Tectonic Setting ...... 11 Chapter 3 ...... 17 Materials and Methods ...... 17 3.1 Petrography ...... 17 3.2 Stable Isotope Analysis ...... 18 3.3 Strontium Isotope Analysis ...... 18 3.4 Fluid Inclusion Studies ...... 19 3.5 Spatial Variability Maps ...... 20 Chapter 4 ...... 21 Results ...... 21 4.1 Petrography of the Devonian Formations ...... 21 4.1.1 Compaction ...... 22 4.1.2 Fracturing ...... 23 4.1.3 Calcite Cementation ...... 25 4.1.4 Dolomitization ...... 29 4.1.5 Anhydrite cementation ...... 32 4.1.6 Silicification ...... 33 4.2 Petrography of the Mississippian Formations ...... 33 4.2.1 Compaction ...... 34 4.2.2 Fracturing ...... 35 4.2.3 Calcite Cementation ...... 35

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4.2.4 Dolomitization ...... 36 4.2.5Anhydrite cementation ...... 38 4.2.6 Silicification ...... 38 4.3 Geochemistry of the Devonian and Mississippian Formations ...... 38 4.3.1 Oxygen and Carbon Isotopes ...... 38 4.3.2 Strontium Isotopes ...... 47 4.4 Fluid Inclusion results of the Devonian and Mississippian Formations ...... 51 Chapter 5 ...... 60 Discussion ...... 60 5.1 Constraints from petrography ...... 60 5.2 Constraints from isotope analysis of saddle dolomite and calcite ...... 64 5.3 Nature of the diagenetic fluids involved in precipitation of fracture-related saddle dolomite 67 5.4 Relationship between fracturing and tectonic events ...... 72 5.5 Effect of fluid flow via fractures on reservoir characterization...... 74 Chapter 6 ...... 76 Conclusions ...... 76 6.1 Conclusions ...... 76 6.2 Future Work ...... 78 6.2.1 Temporal and spatial variability of isotopic signatures, salinities and homogenization temperatures of SD in the Devonian and Mississippian Formations ...... 78 References ...... 85 Appendix I: Nomenclature ...... 101 Appendix II: Geochemical Results ...... 102 Vita Auctoris...... 114

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List of Figures

Figure 1. Map of WCSB showing the Devonian and Mississippian successions. The red circles represent the sampled reservoirs (modified from Richards 1989b) ...... 2 Figure 2. Schematic representation of the three main components of the low-temperature sedimentary hydrothermal mineral association: shale-hosted sedimentary exhalative (SEDEX) Pb-Zn deposits, hydrothermal dolomite (HTD)-hosted MVT Pb-Zn ore bodies, and HTD reservoir facies (Davies and Smith, 2006)...... 7 Figure 3. Models of fracture-related dolomitization (Davies and Smith, 2006; Packard et al., 2001; Packard et al., 1990; Morrow, 1998), Unpublished Al-Aasm, 2015 ...... 10 Figure 4. Structural elements of the WCSB (modified from the Geological Atlas of Western Canada Sedimentary Basin, 1994) ...... 11 Figure 5. Stratigraphic column from Middle Devonian to Mississippian in the Western Canadian Sedimentary Basin. Modified from Core Laboratories Calgary (2010)...... 16 Figure 6. Paragenetic sequence of the Devonian Formations ...... 22 Figure 7. Fractures observed in the Devonian (A, B, C) and Mississippian (D, E, F) Formations: (A) 3 sets of horizontally oriented fractures occluded by saddle dolomite and stylolites, (B) vertically oriented fractures crosscut by early calcite cement, (C) vertically oriented fractures crosscut by stylolites and late calcite cement, (D) breccia and sub-vertical fractures occluded by saddle dolomite , (E) horizontal to sub-vertical microfractures postdated by late calcite cement, (F) 2 horizontal and 1 sub-vertical hairline fracture in calcite ...... 24 Figure 8. Photomicrograph of calcite cement in the Devonian and Mississippian (A) Q1- Quirk Creek calcite cement filling pore space postdating fine crystalline euhedral to subhedral matrix dolomite, (B) Q1 sample from Quirk Creek with calcite cement cathodoluminescence revealing a homogenous dark red color, (C) sample 14-3 from Sikanni showing Calcite cement postdated by pore filling saddle dolomite cement, (D) D1 from Duvernay showing fracture filling calcite cement postdating fine crystalline dolomite, (E) D1 under PPL, (F) D1 sample revealing a homogenous dark red color of calcite cement under CL ...... 26 Figure 9. Photomicrograph of calcite cement from Duvernay (Late Devonian) (A) D2: calcite cement filling pore space postdating fine crystalline matrix anhedral to subhedral dolomite, (B) D6: fracture filling calcite cement postdating fine crystalline dolomite, (C) CL image of D6 showing a homogenous bright red color of calcite cement, (D) D8: pore filling calcite cement postdating fine crystalline dolomite and crosscut by anhydrite cement ...... 27 Figure 10. Types of Dolomites in the Mississippian and Devonian Strata in the Studied Formations ...... 28 Figure 11. Photomicrograph of Devonian saddle dolomite. (A-B) J4 ppl and CL image showing planar subhedral medium dolomite crystals followed by vuggy saddle dolomite formation and quartz infilling pore space, (C) J6: CL image showing different generations of pore filling saddle dolomite cement with multiple growth zones. Under CL, SD displays oscillatory zonation of dull to bright red color with bright red rims,(D) D3: Anhydrite cement postdating saddle dolomite,(E) D5: fracture filling saddle dolomite cement cross cut by stylolite and postdating fine crystalline

matrix dolomite, (F) D7: pore filling saddle dolomite cement postdating fine to medium crystalline matrix anhedral to subhedral dolomite ...... 30 Figure 12. Photomicrograph of Devonian saddle dolomite. (A-B) D7 under PPL and Cl. Saddle dolomite cement filling pore space postdating fine to medium crystalline anhedral to subhedral dolomite. Under CL, SD displays oscillatory zonation of dull to bright red colors with bright red rims, (C)D9: fracture filling saddle dolomite cement postdating fine crystalline dolomite, (D) H1 saddle dolomite crosscutting medium crystalline euhedral to subhedral dolomite, (E) 13-350206 Hamburg: saddle dolomite postdating calcite, (F) 13-350210 Hamburg: fracture filling saddle dolomite cement crosscutting stylolites and postdating calcite ...... 31 Figure 13. Microphotographs of Anydrite cement in Quirk Creek (Mississippian) and Duvernay (Devonian). (A) Q2: pore filling anhydrite cement postdating calcite, (B) Q3: pore filling anhydrite cement postdating medium crystalline anhedral to subhedral dolomite, (C) D5: Anhydrite cement postdating pore filling calcite cement , (D) D8: Anhydrite cement postdating blocky calcite cement ...... 32 Figure 14. Paragenetic sequence of the Mississippian Formations ...... 33 Figure 15. Mechanical and chemical compaction features (A) 14-7 (Sikanni): 1- compaction (peloids) 2- dissolution 3-caclite cementation 4- fracturing (B) 14-8 (Sikanni): stylolites crosscutting skeletal components (peloids) and calcite cement ...... 34 Figure 16. Photomicrograph of Mississippian Saddle dolomite cement. (A)Q4 showing pore filling calcite cement postdating anhydrite and pore filling saddle dolomite cement, (B) 14-12-16 QC showing pore filling saddle dolomite cement postdating planar subhedral to euhedral medium crystalline matrix dolomite, (C) 14-12-18 QC showing saddle dolomite postdating fine crystalline matrix dolomite, (D) 32-9 Sikanni showing saddle dolomite postdating calcite, (E) 32- 10 Sikanni fracture filling saddle dolomite cement crosscutting fine crystalline matrix dolomite ...... 37 Figure 17. δ18O vs δ13C values for saddle dolomite in the studied fields. The boxes represent δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989). Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993) ...... 40 Figure 18. δ18O vs δ13Cfor saddle dolomite in the studied fields by Age. The box represents δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993) ...... 41 Figure 19. δ18O vs δ13Cfor saddle matrix and pervasive dolomite in the studied fields by age. The box represents δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993) ...... 42 Figure 20. δ18O vs δ13C for saddle and matrix dolomite in the studied fields by age. The box represents δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993) ...... 43

Figure 21. δ18O vs δ13Cfor the calcite cement types in the studied areas by fields. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993) ...... 44 Figure 22. δ18O vs δ13C for the calcite cement types in the studied fields by age. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)...... 45 Figure 23. δ18O vs δ13C for fracture and pore filling calcite cement in the studied fields by age. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)...... 46 Figure 24. δ18O vs δ13C of calcite cement in the studied fields by age. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)...... 47 Figure 25. 87Sr/86Sr and δ18O isotopic compositions for calcite phases in the studied fields by age. The boxes represent Middle Devonian seawater (Denison et al., 1997; Veizer et al., 1999) and 87Sr/86Sr and δ18O values for Mississippian seawater (Denison et al., 1994; Banner & Hanson, 1990)...... 48 Figure 26. 87Sr/86Sr and δ18O isotopic compositions for dolomites in the studied carbonates by fields. The boxes represent Middle Devonian seawater (Denison et al., 1997; Veizer et al., 1999) and 87Sr/86Sr and δ18O values for Mississippian seawater (Denison et al., 1994; Banner & Hanson, 1990)...... 49 Figure 27. 87Sr/86Sr and δ18O isotopic compositions for dolomites in the studied fields by age. The boxes represent Middle Devonian seawater (Denison et al., 1997; Veizer et al., 1999) and 87Sr/86Sr and δ18O values for Mississippian seawater (Denison et al., 1994; Banner & Hanson, 1990)...... 50 Figure 28. Fluid Incusions from Quirk Creek: (A &B) Fluid inclusion assemblage in saddle dolomite under 10x & 40x, (B & C): shows six two-phase primary fluid inclusions (liquid rich with vapor bubble) in saddle dolomite ranging in shape from elongate to subcircular and in size from 2 to 6 µm under 100x, (E ): Fluid inclusion assemblage in blocky calcite under 40x, (F): two phase fluid inclusion in blocky calcite under 100x ...... 52 Figure 29. Th vs. salinity of saddle dolomite by fields. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 53 Figure 30. Th vs. salinity of saddle dolomite by age. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 54 Figure 31. Th vs. salinity of calcite cement by fields Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 55 Figure 32. Th vs. salinity of calcite cement by age. Additional data were taken from previous studies cf. (Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 56

Figure 33. Histogram showing the frequency distribution of Th for fluid inclusions from saddle dolomite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 57 Figure 34. Histogram showing the frequency distribution of salinity for fluid inclusions from saddle dolomite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 58 Figure 35. Histogram showing frequency distribution of Th for fluid inclusions from calcite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 59 Figure 36. Histogram showing frequency distribution of salinity for fluid inclusions from calcite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995)...... 59 Figure 37. Calculated oxygen isotopic composition of the dolomitization fluid from saddle dolomite (SD) and matrix dolomite (MD) (expressed in VSMOW). Fractionation equation that is used is from Land (1983)...... 70 Figure 38. Fluid oxygen isotopic composition vs. formation temperature for calcite in the Mississippian and Devonian. Fractionation equation that is used is from Friedman and O'Neil (1977). Formation temperature for early Mississippian and Devonian calcite are estimated from Al-Aasm and Vernon (2007) and Clarke (1998)...... 71 Figure 39. Spatial variation of the oxygen isotopic values of saddle dolomite for the Mississippian and Devonian fields ...... 81 Figure 40. Spatial variation of the carbon isotopic values of saddle dolomite for the Mississippian and Devonian fields ...... 82 Figure 41. Spatial variation of the homogenization temperature of saddle dolomite for the Mississippian and Devonian fields ...... 83 Figure 42. Spatial variation of the salinity values of saddle dolomite for the Mississippian and Devonian fields ...... 84

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List of Tables

Table 1. Characteristics of the sampled areas ...... 17 Table 2. Dolomite isotope results summary from previous and current data (data with * are from the current study) ...... 103 Table 3. Calcite Isotope results summary from previous and current data (data with * are from the current study) ...... 108 Table 4. Summary of fluid inclusion results from previous and current data for saddle dolomite (results from Hamburg, Sikanni and Jedney are from Clarke, 1998, White, 1995 and Al-Aasm, 1996; Duvernay and Quirk Creek results are from the current study) ...... 111 Table 5. Summary of fluid inclusion results from previous and current data for calcite (results from Hamburg and Sikanni are from Clarke, 1998 and White, 1995; Duvernay and Quirk Creek results are from the current study) ...... 113

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Chapter 1 Introduction

The Alberta basin and the southwestern Northwest Territories; the Williston Basin (southeastern

Alberta) and the Rocky Mountain Deformed Belt Province of western Alberta and eastern British

Columbia constitute the Western Canada Sedimentary Basin (WCSB; Wright, 1984).

Undiscovered conventional resources from provinces in the WCSB are 1,321 million barrels of oil, 25,386 billion cubic feet of gas, and 604 million barrels of natural gas liquids as reported by the U.S. Geological Survey (Higley, 2013). The natural exposure of almost all the basin strata in the Rocky Mountain thrust belt has made WCSB an ideal research area for sedimentologists and stratigraphers due to their two- and three-dimensional surface exposures in the deformed belt.

The Western Canada Sedimentary Basin (WCSB) has been the subject of intensive research due to its high economic potential in terms of hydrocarbon resources with 20.8 % of the gas reserves and 14.4% of recoverable oil reserves sourced from Mississippian carbonates (GSC Maps 1558A,

1559A) along with 60% of the total conventional oil and 20% of the total natural gas sourced from

Devonian carbonate formations (Energy Resource Conservation Board of Alberta, 1985). Figure

1 represents a map of WCSB showing the Devonian and Mississippian successions that were covered in this study.

Sikanni Jedney Hamburg

Duvernay

Quirk Creek

Figure 1. Map of WCSB showing the Devonian and Mississippian successions. The red circles represent the sampled reservoirs (modified from Richards 1989b)

Most of the current and previous research had focused on specific fields within a formation and on diagenesis, dolomitization and sedimentology as a whole. A regionally comprehensive study of fracture mineralization and their tectonic significance covering Mississippian and Devonian dolostones extending from Alberta to British Columbia has not been carried out in detail yet.

1.1 Purpose of Study:

The purpose of the present work is to determine the relative timing and evolution of fracture mineralization in Devonian and Mississippian carbonates of western Canada and to distinguish between the hypotheses of whether the diagenetic fluids that precipitated the minerals originated during Antler’s (late Devonian to early Pennsylvanian) or later during the Laramide (late

Cretaceous to Paleogene) Orogeny. Additional questions to be addressed were: (1) if fluids that precipitated diagenetic minerals in these fractures were restricted to certain pay zones (or formations) or belong to the same stratigraphic columns, (2) whether the diagenetic fluids maintained the same composition during the diagenetic history, and (3) what is the effect of fluid flow via fractures on reservoir characterization. The above questions were to be addressed by using detailed integrated petrography, stable isotope and strontium isotope analysis and a fluid inclusion study. Hydrocarbon traps and the transportation of various fluids through channels that influence the development of reservoirs are provided by fractures (Stein, 1977); hence, the amount of hydrocarbons that can be produced is a function of the fracture network connectivity and geometry.

Therefore, this study will aid in better understanding the evolution of diagenetic fluids within the

WCSB and their relationship to tectonic history of the basin by focusing on the evaluation of fracture mineralization of Mississippian and Devonian dolostone reservoirs from Alberta and BC.

2.2 Previous Studies

In this thesis, the previous studies are confined to aspects that deal with diagenesis (including fracture diagenesis) and dolomitization of Mississippian and Devonian dolomites in WCSB and examples from other basins. Diagenesis of carbonate sediments encompasses all the processes that affect the sediments after deposition until the realm of incipient metamorphism (Tucker, 1990).

These processes include cementation, dissolution, mechanical and chemical compaction, dolomitization and recrystallization. Hydrothermal dolomitization applied in this thesis is defined in accordance with Davies and Smith (2006) who defined hydrothermal dolomite as

“dolomitization occurring under burial conditions, commonly shallow depths, by fluids (typically very saline) with temperature and pressure (T and P) higher than the ambient T and P of the host formation” (see also Machel and Lonnee, 2002).

Several studies have been done on diagenesis and dolomitization of WCSB including Machel et al. (1996), Qing & Mountjoy (1994), Ayalon & Longstaffe (1988), Billings et al. (1969), Al-Aasm et al. (2002), Luo & Machel (1995) and Nesbitt & Muehlenbachs (1994). Ross and Bustin (2008) studied the Devonian–Mississippian strata in the Western Canada sedimentary basin to characterize its shale gas resource potential. Research on the depositional environments and stratigraphy of the Devonian and Mississippian formations in WCSB include Cameron (1968),

Crawford (1972), Craig (1987), Gosellin (1990), Proctor and Macauley (1968), Richards (1989),

Law (1981) and Durocher & Al-Aasm (1997).

According to Clarke (1998) and Al-Aasm and Clarke (2004) dolomitization and calcite cementation were the major diagenetic processes that occurred in the Slave Point Formation

(Middle Devonian) of the Hamburg field located in northwestern Alberta. Several types of calcite cements (radial fibrous, bladed/prismatic, calcite spar and blocky calcite cement) have been recognized based on petrography and cathodoluminescence. Dolomitization within the Hamburg

Field during burial could have been related to faults associated with tectonic events that may have channeled fluids into the Slave Point Formation, hence, fault and fracture systems at the time of precipitation controlled the distribution of dolomite. Matrix dolomite (MD), pseudomorphic dolomite (PMD), pervasive dolomite (PD) and saddle dolomite (SD) were the four types of dolomite recognized by Clarke (1998).

Gale et al. (2004) linked diagenesis and fractures to predict and characterize fractures in dolomite reservoirs from the Lower Ordovician Ellenburger and Permian Clear Fork formations in West

Texas, and the Lower Ordovician Knox Group in Mississippi, along with outcrop samples of

Lower Cretaceous Cupido Formation dolostones from the Sierra Madre Oriental, Mexico.

Understanding the rocks diagenetic history and the way diagenesis interacts with fracture growth

aided in studies of fracture diagenesis and fracture characterization. They used rock properties at the time of fracturing (particularly subcritical crack index) and the pre-fracturing diagenetic processes to determine the fracture architecture. They proposed that by analyzing details of the timing of diagenetic events relative to fracturing, a structural-diagenetic sequence may be established and once the sequence is known, estimation of rock properties at the time of fracturing could be determined.

Laubach et al. (2010) suggested that in order to understand how cement fills fractures, the timing of fracture growth relative to diagenetic reactions should be considered. The timing and rate at which fractures open is determined by fluid inclusions trapped within isolated cement deposits in otherwise open fractures (Becker et al., 2010). Reconstruction of fluid temperature and pore fluid pressure evolution during fracture opening and evaluation of fracture age could be achieved using fluid inclusion data along with textural cross-cutting relations which will aid in choosing the right geologic model for the distribution of fractures prediction (Laubach et al., 2010). They also reported that fluid flow is limited by the degree of cement fill in fractures rather than fracture orientation and the occurrence of flow was restricted to fractures that are not sealed with cement.

Ardakani et al. (2013) used integrated field, petrographic, fluid inclusion and isotope geochemistry to study fracture mineralization and fluid flow evolution in the Ordovician to Devonian carbonates, southwestern Ontario, Canada. Diverse fluids were involved in dolomitization and⁄or

18 recrystallization of dolomite as evidenced by the δ Ofluid, ∑REE, and REESN patterns of matrix and saddle dolomite. All samples from the Devonian to Ordovician were characterized by high fluid inclusion homogenization temperatures (>100°C) suggesting a role for hydrothermal fluids in precipitation and/or recrystallization of dolomite.

Al-Aasm (2003) studied the role of hydrothermal fluids in the formation of Mississippian and

Devonian dolomites in Western Canada Sedimentary Basin. The shallow burial environment was characterized by earlier hydrothermal incursions, whereas during and after the Laramide tectonic event generation of later hot fluids took place. Higher salinity, lower temperature and variable isotopic signatures characterized the earlier hydrothermal compared to the later one.

Lavoie & Chi (2006) investigated the hydrocarbon reservoir potential of the hydrothermal dolomites in in the Lower Silurian La Vieille Formation in Northern New Brunswick. Other examples of hydrothermal dolomitization include the Devonian Wabamun formation from

Parkland Field (Packard et al., 2001), Manetoe dolomite (Morrow et al., 1986), dolomites from the

Key River Formation (Qing and Mountjoy, 1989) and the Wabamun dolomites in Peace River area (Packard et al., 1990).

Davies and Smith (2006) suggested that hydrothermal dolomite facies are characterized by saddle dolomite in both replacive and void filling modes. They concluded that hydrothermal processes were active at some stage of basin evolution, thus enhancing prospectivity for hydrothermal dolomite (HTD) reservoirs as evidenced from the occurrence of Sedimentary exhalative deposits

(SEDEX)and/or Mississippi-Valley Type (MVT) deposits in a sedimentary basin. This conclusion was based on the association between the three hydrothermal end members: SEDEX, MVT and

HTD (Fig. 2). Extensional faults, strike-slip (wrench) faults, and intersections of extensional and/or wrench faults, including transfer faults were the main structural settings that favored structurally controlled hydrothermal fluid movement.

Figure 2. Schematic representation of the three main components of the low-temperature sedimentary hydrothermal mineral association: shale-hosted sedimentary exhalative (SEDEX) Pb- Zn deposits, hydrothermal dolomite (HTD)-hosted MVT Pb-Zn ore bodies, and HTD reservoir facies (Davies and Smith, 2006).

Ma et al. (2006) studied the Devonian Wabamun Group (northeast British Columbia, Canada) and proposed based on numerical modeling that faults are a major controlling factor in hydrothermal fluid flow. They concluded that hydrothermal fluid flow during the Antler orogenic tectonism resulted in the formation saddle dolomite and replacement chert in the Wabamun Group.

Adam (2000) demonstrated that dolomitization and calcite cementation and replacement (bladed/ prismatic, granular/ mosaic, neomorphosed and calcite spar) were the major diagenetic processes affecting the carbonates from the Upper Devonian Duvernay Formation. Matrix dolomite (MD), pervasive dolomite (PD), saddle dolomite (SD) pseudomorphic dolomite (PMD), and dissolution seam associated dolomite (D) were the five types of dolomite recognized in the Duverrnay

Formation.

Gao (2001) suggested that cementation, dolomitization and pyritization were the main diagenetic processes affecting shale and mudstone lithofacies in the Devonian Duvernay Formation in Central

Alberta. An early diagenetic origin was proposed for non-ferroan calcite cement and matrix dolomite, and framboidal pyrite; and an intermediate to deep burial origin was suggested for bladed calcite cement, ferroan type II matrix dolomite, saddle dolomite, vein associated dolomite and coarse grained pyrite. An anoxic, partially closed to open environment was suggested for the deposition of shales and mudstones in the Duvernay, based on sulphur isotopic results, TOC ratios, organic facies combined with the size distribution of framboidal pyrite and lack of bioturbation.

White & Al-Aasm, (1997) demonstrated that secondary, intercrystalline, vuggy and fracture porosity resulting from diagenetic processes were the major types of porosity in the Upper Debolt

Formation, Sikanni field (Mississippian) and micritization, neomorphism, cementation, compaction, silicification, and dolomitization were the major diagenetic events involved. Pre- compaction early dolomite (ED), matrix dolomite (MD), pseudomorphic dolomite (PD), coarse crystalline dolomite (CCD) and saddle dolomite (SD) were the five main dolomite types recognized based on crystal size, distribution and abundance. Based on geochemical and petrographic evidence combined with fluid inclusion analysis, a hydrothermal origin of SD was suggested by this study.

Lu (1993) reported that cementation, compaction, silicification, dolomitization and anhydritization were the major diagenetic events in the Turner Valley Formation. Microdolomite, patchy dolomite, pervasive matrix dolomite and megadolomite were the four main dolomite types recognized based on texture, distribution, abundance and geochemistry.

Figure 3 shows some of the typical models to explain the formation of fracture related dolomitization. Different models of dolomitization of the Wabamun Group were proposed: fault

associated hydrothermal karst and dolomitization model by Packard et al (1990, 2001) and the fault and fracture controlled model by Stoakes (1987) and Churcher and Majid ( 1989), which was supported by Mountjoy and Halim Dihardja (1991) where expulsion through mechanical compaction and seismic pumping from the movement of brines and hypersaline fluids along faults and fractures at shallower depth caused the formation of dolomite. An opposing study by Workum

(1991) suggested that subaerial exposure (due to eustatic sea level drop) and karstification (due to carbonate rocks freshwater dissolution) caused the dolomitization of the Wabamun Group. Facies controlled dolomitization and hydrothermal process of dissolution and dolomitizaion were the two- staged process suggested by Saller and Yarekmo (1994) to explain the dolomitization of the

Wabamun Group.

Packard et al. (2001) BANFF SEA POSSIBLE TRIGGER MECHANISMS FOR Packard et al., 1990 PRECIPITATION 1. NON-ISOTHERMAL BOILING OF "TIGHT" WABAMUN ASCENDING QUARTZ SAT. FLUIDS LIMESTONE 2. THERMAL QUENCHING DUE TO no replacement EFFECT OF "COOL" SEAWATER microquartz below this line 3. FLUID MIXING (e.g. BASINAL & Morrow, 1998 SEAWATER) WITH VARYING SATn OR Ca/Mg RATIOS

SILICA SOURCED (DISSOLVED) FROM 300oC GRANITE WASH

Figure 3. Models of fracture-related dolomitization (Davies and Smith, 2006; Packard et al., 2001; Packard et al., 1990; Morrow, 1998), Unpublished Al-Aasm, 2015

In all of the above mentioned studies, the main focus was on the diagenetic history of carbonates

in fields from Western Canada Sedimentary Basin and on fracture diagenesis in general. However,

they lacked detailed study of the fractures observed and their tectonic significance.

Chapter 2 Geologic and Tectonic Setting

A northwest-trending trough in front of the Cordilleran Fold and Thrust Belt termed the Alberta

Basin and the cratonic Williston Basin along with the eastern Canadian Cordillera constitute the

Western Canada Sedimentary Basin (Fig. 4). The above sedimentary Basins are separated by the

Bow Island Arch (Wright, 1984).

Jedney Hamburg Sikanni

Duvernay

Quirk Creek

Figure 4. Structural elements of the WCSB (modified from the Geological Atlas of Western Canada Sedimentary Basin, 1994)

A major east-northeast trending basement structure called the Peace River Arch (Fig. 4) extended from the Cordillera towards the craton across northeastern British Columbia and northwestern

Alberta (Cant, 1988).The Peace River Arch in the Mississippian to Permian time became the site of a faulted basin termed the Peace River Embayment. Prior to the Mississippian that Arch represented a topographic high in Cambrian to late Devonian time.

The Foreland Fold and Thrust Belt and the Omineca Belt termed the Cordilleran structural elements formed due to the Middle Jurassic to Eocene compressive deformation of the western edge of the WCSB and caused deformation of the Middle Proterozoic to Eocene strata (Wright,

1984). Deposition of Oligocene strata in the Flathead Valley Graben (southeastern British

Columbia) resulted from the regional extension following the compressive deformation. The

Mesozoic and Cenozoic evolution of the entire WCSB was significantly affected by the loading of the North American craton and the creation of western source areas during formation of the

Cordilleran Foreland Fold and Thrust Belt (Wright, 1984).

Examples of structural features from WCSB include: (1) horsts and grabens in the Fort Macleod area of southernmost Alberta. ; (2) Liard Basin at the north end of the Alberta Basin; and (3) Hay

River Fault (northeast trending) between the Peace River Arch and the Tathlina Arch (Wright,

1984)

A thickness of above 6 km east of the deformed belt in the Liard Basin, and southward to over 3 km in the Canadian portion of the Williston Basin characterize the Phanerozoic sedimentary wedge from the Canadian Shield. During the Cordilleran Orogeny, the Williston Basin became isolated in the late Jurassic period. The Cambrian to Cretaceous interval in the Canadian Rockies thickens to the west. Despite the removal by uplift and erosion of the Phanerozoic section within the fold and thrust belt, a thickness of above 8 km remains for the Paleozoic strata (Wright, 1984).

Extensional tectonics produced the Liard Basin and the east-west oriented Peace River Embayment during the late Devonian-Mississippian Antler Orogeny. During the late Mississippian

(Pennsylvanian period) a structural feature near the eastern part of the Peace River Embayment termed the Dunvegan Fault was active. The Prophet Trough of Western Canada, which developed during the late Devonian to early Carboniferous and persisted into late Cretaceous, contained the thickest Carboniferous sections (Wright, 1984). Richards et al. (1994) suggested its extension from southeastern British Columbia to the late Devonian and early Carboniferous Yukon Fold Belt as well as the Prophet Trough connection to the Antler Foreland Basin (Western United States).

Monger et al (1982) argued that the most extensive deformation occurred during the Columbian

Orogeny (late Jurassic to early Cretaceous) and the Laramide Orogeny (late Cretaceous to

Paleocene) resulting in today’s thrust faulting and folding. Further compactional deformation to the underlying sediments was caused by progressive tectonic and sedimentary loading (increase in temperature) due to the extensive onlapping of thrust sheets and the increased uplift of the Western

Canadian Sedimentary Basin (White, 1995).

Majorowicz et al. (1985, 1986) demonstrated that with depth in the NE section of the Rockies there exists a decrease in heat flow by using the thermal data of current heat flow in the Mesozoic and

Paleozoic strata of the WCSB. Starting from recharge areas of the Rocky Mountains through deep aquifers to lowland discharge areas, large scale fluid migration occurred which caused the above trend (Majorowicz et al., 1985, 1986). White (1995) argues that a period of uplift and erosion existed in the Sikanni Field in NE B.C. during the Pennsylvanian to the start of the Permian as indicated by the presence of the Belloy Formation overlying the Stoddart Group.

Richards (1989) reported that the main tectonic elements of the Western Canada Sedimentary

Basin in the late Devonian period were the Prophet Trough on which he described as “the

downwarped and downfaulted western margin of the North American Plate of the late Devonian and Carboniferous time” and the Peace River Embayment. During the Antler and Ellesmerian

Orogenies and between latest Devonian and early Carboniferous period the Prophet Trough subsided by loading and contraction, whereas during the Cariboo Orogeny in British Columbia contraction caused its subsidence (Richards, 1989; White, 1959; Sutherland Brown, 1963;

Leithiers et al., 1986). In the early stages of the Peace River Embayment (formed by subsidence or inversion of the Peace River Arch) Evolution, it was a part of the Prophet trough and during late

Tournasian it became a “distinct element” (Richards, 1989). Block faulting of the Arch occurred due to crustal extension during the Antler Orogeny and was followed by block subsidence.

Conduits for the movement of diagenetic fluids were provided by these fault movements which also formed structural hydrocarbon traps in the Peace River area (Cant, 1988; Halberststma, 1996).

Figure 5 shows the main rocks units of the Devonian and Mississippian periods in WCSB.

British Columbia Alberta

South Central Fort Nelson Southern Plain Central Plains North West Plains Mountains

Kiskatinaw Etherington Gonata

Mount Head Mount Head

Serpukhovia n Debolt Mounthead Debolt

Turner Valley Turner Valley Elkton

Shunda Shunda Shunda Shunda Shunda

Visean

Rundle Group Rundle

Mississippian Pekisko Pekisko Pekisko Pekisko Pekisko

Banff Banff Banff Banff Banff

Exshaw Exshaw Exshaw Exshaw Exshaw

Tournasian

Kotcho

Big Valley Big Valley Big Palliser

Tetcho

Wabamun Wabamun Wabamun

Famennian

Trout River Stettler Stettler

Crowfoot

evonian

Ireton D Kariska Red Knife Alexo

Nisku

Simpson

Frasnian

Southesk (White Fort Fort Simpson Ireton

Reef) Winterburn Ireton

Leduc

Woodbend Group Woodbend Leduc Le d uc

Cairn (Black Reef) Cooking Lake

Duvernay

Waterways Waterways

Slave Point

Slave Point Slave Point

Givetian lls Fort Fort Vermillion Vermilion

Beaverhill Lake Group Lake Beaverhill

Beaverhill Lake Beaverhill SwanHi Figure 5. Stratigraphic column from Middle Devonian to Mississippian in the Western Canadian Sedimentary Basin. Modified from Core Laboratories Calgary (2010).

Chapter 3 Materials and Methods

Sampling for the studied fields (Fig. 1) include Sikanni and Quirk Creek fields from the

Mississippian strata along with Hamburg and Jedney fields from the Devonian successions and the Devonian Duvernay Formation that included several wells in Central Alberta. Core samples were collected previously by graduate and undergraduate students who worked on those fields

(White, 1995; Adam, 2000; Clarke, 1998; Hu Lu, 1993). Fractured samples were chosen based on their geologic distribution extending from Alberta to British Columbia, age and time of deposition

(Mississippian and Devonian) and their tectonic setting. The sample scheme is presented in Table

Field Formation Age Location Sikanni Upper Debolt Mississippian North East British Columbia Hamburg Slave Point Middle Devonian North Western Alberta Upper Quirk Creek Turner Valley South Western Alberta Mississippian Jedney Slave Point Middle Devonian North East British Columbia - Duvernay Upper Devonian Central Alberta Table 1. Characteristics of the sampled areas The following methods were used to achieve the objectives of this study:

3.1 Petrography

The lithofacies of the collected samples along with the diagenetic changes were determined prior to commencement of the isotopic analysis. Transmitted light microscopy was the primary method used for determining the textures (mineralogy, grain size and shape, sorting, fabric, porosity and permeability) along with the diagenetic features.

For the purpose of a detailed description of the diagenetic features and the fractures recognized, thin sections (n=100) were examined under a standard petrographic microscope.

Cathodoluminscence characteristics of host rock and fracture-filling carbonates were determined using a Technosyn Model 8200 MKII with a 12-15Kv beam and a current intensity of 0.42-0.43 mA.

3.2 Stable Isotope Analysis

The source and nature of fluids responsible for fracture mineralization and dolomite formation were constrained by comparing δ18O and δ13C values of diagenetic phases in the study areas (e.g.

Uysal et al., 2000, Azmy et al., 2009). Different sources of fluids responsible for fracture-fill and fluid movement in the study areas were suggested based on isotopic composition of dolomite and calcite and the spatial variation of oxygen and carbon stable isotope values combined with their paragenetic sequence.

A microscope-mounted drill assembly was used to extract samples from fracture-fill and host rocks for oxygen and carbon isotopes. The extraction methods proposed by Al-Aasm et al. (1990) was used where 100% pure phosphoric acid reacted in vacuo with the carbonate mineral samples for a minimum of 4 h at 25o and 50°C for calcite and dolomite, respectively. A Delta-Plus mass spectrometer was used to measure and calculate the isotopic ratios for the evolved CO2 gas. Values were reported in per mil (‰) relative to the VPDB standard and corrected for phosphoric acid fractionation for O and C isotopes. Precision was better than 0.05 ‰ for both isotopes.

3.3 Strontium Isotope Analysis

The type of fluids involved in the formation of calcite and dolomite cements was constrained using

87Sr/86Sr ratios, which are used as a geochronological tool for marine sediments as well (e.g.

McNutt et al., 1987; Veizer et al., 1999). In order to eliminate the pore salts that result from drying, the determination of 87Sr/86Sr ratios of selected dolomite and calcite samples was completed after washing the samples with distilled water which were then reacted with 0.1% HCl and an automated

Finnigan MAT 261TM mass spectrometer was used to analyze the samples. The static multicollector mode with Re filaments was used to perform all the analyses and by normalization to 86Sr/88Sr = 0.1194 a correction for isotope fractionation during the analyses was achieved. The mass spectrometer performance had a mean standard error of 0.00003 for NBS- 987.

3.4 Fluid Inclusion Studies

“Fluid inclusion refers to any inclusion that trapped a phase that was a fluid at the temperature and pressure of formation, regardless of the phase state of the inclusion as observed at laboratory conditions” ( Bodnar, 2003). Two basic types of information can be provided by fluid inclusions:

(1) an estimate of mineral formation temperature (given that there is no leakage of material into or out of the inclusion after trapping); and (2) the density and composition of the fluid (Emery and

Robinson, 1993).

Detailed petrography was completed to determine the type of inclusions (primary or secondary/ pseudosecondary) using an Olympus BX51 microscope based on the criteria specified by Roedder

(1984). Orientation of the fluid inclusion in the direction of growth and restriction of a fluid inclusion in a distinct growth zone are among the petrographic evidence that supports entrapment during crystal growth (primary fluid inclusions).The temperature, salinity and evolution of fluids was determined using fluid inclusion analysis compiled with petrographic studies data to demonstrate the origin and types of fluids and effects of fluid-rock interaction on diagenetic events.

Doubly polished calcite and dolomite wafers from the previous studies combined with new additional data from this study were used for fluid inclusion analysis. Homogenization (Th), first

(Te) and final melting temperatures (Tm) were measured for both calcite and dolomite. The former is the minimum entrapment temperature, i.e. the temperature of mineral precipitation (Goldstein and Reynolds, 1994). Eutectic temperature (Te) is the temperature at which one solid phase melts completely. Tm is the temperature at which the last solid phase (usually ice; i.e. Tmice) melts in an aqueous fluid inclusion and reflects the trapped diagenetic fluid salinity (Goldstein and Reynolds,

1994). Measured Tmice is reported as wt. % NaCl eq. using the relation of Hall et al. (1988) and

Bodnar (1992). The microthermometric measurements were performed using a Linkam TH600 heating-freezing stage, coupled with the Olympus BX60. The thermocouple was calibrated using synthetic pure water and CO2 inclusions.

3.5 Spatial Variability Maps

The spatial variability maps in the future work section were completed using the ArcGIS software.

The spatial analyst tool and the Kriging interpolation method was used to create prediction surface maps to determine if spatial variability of isotopic signatures, homogenization temperatures and salinities of SD existed within WCSB.

Chapter 4 Results

4.1 Petrography of the Devonian Formations

Petrography of the studied carbonate reservoirs is based on reevaluation of previous studies done on these reservoirs (White, 1995; Adam, 2000; Clarke, 1998; Hu Lu, 1993, Al-Aasm, 1996) and current evaluation by the author. For dolomite classification Sibley and Gregg (1987) scheme was applied.

The main diagenetic processes included compaction, fracturing, calcite cementation, dolomitization, anhydrite cementation and silicification. Several types of fracture- and pore-filling cements (calcite, saddle dolomite and anhydrite) were recognized. Paragenetically, saddle dolomite occluded fractures and vugs, predated by early calcite cement but postdated by late calcite cement, anhydrite and sometimes quartz (Fig. 6). The host rock is characterized by fine (5 - 15

µm) and medium (30-150 µm) crystalline euhedral to subhedral dolomite.

Diagenetic Process Early Late Fine crystalline matrix dolomite

Medium crystalline matrix dolomite Early pore filling equant calcite cement Early fracture filling calcite cement Mechanical compaction Chemical Compaction Pervasive dolomite Pore filling saddle dolomite Fracture filling saddle dolomite Late pore and fracture filling blocky calcite cement Silicification Anhydrite Figure 6. Paragenetic sequence of the Devonian Formations 4.1.1 Compaction

Compactional textures and fabrics develop due to an increase in overburden pressure. These textures are divided into mechanical (physical) and chemical compaction. Choquette and James

(1987) reported that mechanical compaction commences directly after deposition (one metre deep), whereas chemical compaction requires several hundred metres of burial.

Mechanical Compaction:

Mechanical compaction results in a decrease in permeability, sediment thickness and porosity along with closer grain packing, dewatering and fracturing, and re-orientation and breakage of allochems (cf. Shinn and Robin, 1983). The Devonian formations are characterized by mechanical compaction features including grain fractures and tighter grain packing prior to cementation which caused a reduction in porosity (Fig. 9A). Minor evidence of mechanical compaction is observed in the Slave Point Formation possibly due to the resistance of physical compaction by early calcite cementation which lithified the sediments (Clarke, 1998).

Chemical Compaction:

Increase in overburden pressure leads to the formation of dissolution seams and stylolites associated with the onset of chemical compaction. Tucker and Wright (1990) defined dissolution seams as smooth, anastomosing features of insoluble residue (e.g. clays, sulphides) that deflect around and between grains. Dissolution seams in the studied Devonian fields formed after matrix dolomites and early calcite cement but was postdated by late calcite cement. Stylolites represent a late diagenetic event postdating late calcite cement and predating silica formation, but also occasionally formed prior to late calcite cement and saddle dolomite (Fig. 11E).

4.1.2 Fracturing

Three generations of fractures are observed in the Devonian Formation. Thin randomly oriented fractures (0.5-1 cm) filled with early calcite cement represent the first generation of fractures (Fig.

7B). Larger subvertical fractures (1-3 cm) occluded by saddle dolomite represent the second generation (Fig. 7A). The last generation of fractures (1-5cm) are vertically oriented fractures filled with late blocky calcite cement and crosscutting saddle dolomite (Fig. 7C).

A B

C D

F E

Figure 7. Fractures observed in the Devonian (A, B, C) and Mississippian (D, E, F) Formations: (A) 3 sets of horizontally oriented fractures occluded by saddle dolomite and stylolites, (B) vertically oriented fractures crosscut by early calcite cement, (C) vertically oriented fractures crosscut by stylolites and late calcite cement, (D) breccia and sub-vertical fractures occluded by saddle dolomite , (E) horizontal to sub-vertical microfractures postdated by late calcite cement, (F) 2 horizontal and 1 sub-vertical hairline fracture in calcite

4.1.3 Calcite Cementation

Two types of calcite cements were observed in the Devonian samples: pore filling and fracture filling ranging in size from 30 to 1000 µm (Figs. 8 and 9). Pore filling calcite cement varied in 2 types: blocky and equant calcite spar cement. Blocky calcite (50 to 500 µm) cement is present in dolomitized wackestones filling pores left by dissolution of grains including corals, foraminifera and ooids where they have entirely filled the interparticle porosity. Blocky calcite represents a late stage diagenetic event in the Devonian formations and is characterized by coarse equant crystals. Calcite spar cement filled pores in brachiopods and gastropods along with occluding matrix and intraparticle porosity in corals and stromatoporoids , ranged in size from 20 to 150 µm and was characterized by equant crystals. Pore filling calcite cement displays a homogenous dull red color under CL (Fig. 8F).

Fracture filling equant calcite (FFC) cement ranges in size from 50 to 200 µm and it is euhedral to subhedral in shape, occurred only in the Duvernay Formation from the studied field in the Devonian and is not luminescent under CL. FFC represented an early calcite cement phase that postdates fine and medium crystalline matrix dolomites (MD). Pore filling blocky late calcite cement postdates fracture filling calcite and formed after the pore filling saddle dolomite cement.

A B

50µm 50µm

C D

50µm 50µm

E F

50µm 50µm

Figure 8. Photomicrograph of calcite cement in the Devonian and Mississippian (A) Q1- Quirk Creek calcite cement filling pore space postdating fine crystalline euhedral to subhedral matrix dolomite, (B) Q1 sample from Quirk Creek with calcite cement cathodoluminescence revealing a homogenous dark red color, (C) sample 14-3 from Sikanni showing Calcite cement postdated by pore filling saddle dolomite cement, (D) D1 from Duvernay showing fracture filling calcite cement postdating fine crystalline dolomite, (E) D1 under PPL, (F) D1 sample revealing a homogenous dark red color of calcite cement under CL 26

A B

50µm 50µm

C D

50µm 50µm

Figure 9. Photomicrograph of calcite cement from Duvernay (Late Devonian) (A) D2: calcite cement filling pore space postdating fine crystalline matrix anhedral to subhedral dolomite, (B) D6: fracture filling calcite cement postdating fine crystalline dolomite, (C) CL image of D6 showing a homogenous bright red color of calcite cement, (D) D8: pore filling calcite cement postdating fine crystalline dolomite and crosscut by anhydrite cement

Type of Dolomite Typical Petrographic Characteristics

FCMD Fine Crystalline Size:4 to 15 µm Shape: euhedral to Matrix Dolomite subhedral and anhedral (FCMD) Dark red color under CL

MCMD Size: 20 to 150 µm Medium Crystalline Shape: euhedral to Matrix Dolomite subhedral and anhedral (MCMD) Dark red color under CL

Size: from 200 to 500 µm Shape: subhedral to Coarse Crystalline anhedral crystals CCD Dolomite (CCD) Dull red luminescent cores and bright red rims under CL

fabric destructive Pervasive Dolomite Size:50 to 250 µm PD (PD) Dull brownish red color with bright red rims under CL

Sweeping extinction and curved crystal faces Pore filling size :20 to 150 SD Saddle Dolomite µm Fracture filling size: 50 (SD) to 500 µm Oscillatory zonation of dull to bright red colors with dark red rims under CL Figure 10. Types of Dolomites in the Mississippian and Devonian Strata in the Studied Formations

4.1.4 Dolomitization

Four main types of dolomite are documented in the Devonian carbonates (Fig.10): (1) fine crystalline subhedral and anhedral matrix dolomite (FCMD) ranged in size from 4 to 10 µm occurring as a host rock and is characterized by dark, red color under CL; (2) medium crystalline matrix dolomite (MCMD) ranges in size from 30 to 100 µm occurring as a host rock and consisted of euhedral to subhedral and anhedral crystals. FCMD and MCMD dolomite replaced fossil fragments as well as matrix /cement and represents an early diagenetic event. Based on petrographic observations including the deflection of dissolution seams around dolomite crystals and truncation of MD by low amplitude stylolite, indicate precipitation of matrix dolomite occurred prior to intensive mechanical and early chemical compaction (Clarke, 1998), hence confirming that MD (FCMD-MCMD) is an early diagenetic phase; (3) pervasive dolomite (PD) is fabric destructive, ranges in size from 50 to 250 µm, displays a dull brownish red color with bright red rims under CL and replaces mud and fossil components. PD is predated by early calcite cement and fine crystalline matrix dolomite and postdated by saddle dolomite and late calcite cement; and (4) saddle dolomite, which is represented by two principal types: a pore filling ranges in crystal size from 20 to 150 µm and a fracture filling ranges in size from 50 to 300 µm. Large crystal size, sweeping extinction and curved crystal faces are the main characteristics of saddle dolomite (Radke & Mathis, 1980). SD cement postdates early calcite cement and medium crystalline matrix dolomite (Figs 11 and 12), predates late calcite cement and anhydrite, and is occasionally succeeded by quartz in Jedney (Devonian) and crosscut by stylolites. Petrographic examination shows that SD exhibits oscillatory zonation of dull to bright red colors with dark red rims under CL (Figs. 11c and 12b)

A B

50µm 50µm

C D

50µm 50µm

E SD F

50µm 50µm

Figure 11. Photomicrograph of Devonian saddle dolomite. (A-B) J4 ppl and CL image showing planar subhedral medium dolomite crystals followed by vuggy saddle dolomite formation and quartz infilling pore space, (C) J6: CL image showing different generations of pore filling saddle dolomite cement with multiple growth zones. Under CL, SD displays oscillatory zonation of dull to bright red color with bright red rims,(D) D3: Anhydrite cement postdating saddle dolomite,(E) D5: fracture filling saddle dolomite cement cross cut by stylolite and postdating fine crystalline matrix dolomite,

(F) D7: pore filling saddle dolomite cement postdating fine to medium crystalline matrix anhedral to subhedral dolomite

A B

50µm 50µm

C D

50µm 50µm

E F

50µm 50µm

Figure 12. Photomicrograph of Devonian saddle dolomite. (A-B) D7 under PPL and Cl. Saddle dolomite cement filling pore space postdating fine to medium crystalline anhedral to subhedral dolomite. Under CL, SD displays oscillatory zonation of dull to bright red colors with bright red rims, (C)D9: fracture filling saddle dolomite cement postdating fine crystalline dolomite, (D) H1 saddle dolomite crosscutting medium crystalline euhedral to subhedral dolomite, (E) 13-350206

Hamburg: saddle dolomite postdating calcite, (F) 13-350210 Hamburg: fracture filling saddle dolomite cement crosscutting stylolites and postdating calcite 31

4.1.5 Anhydrite cementation

Anhydrite cement in the Devonian successions occurred as a late stage diagenetic mineral phase and is mainly present in the Duvernay Formation (Fig. 13). Two main types of anhydrite cement are identified: (1) pore filling (20-150 µm) and (2) fracture filling (50-150 µm). It commonly postdates fracture/ pore filling calcite and saddle dolomite cement.

A B

50µm 50µm

C D

50µm 50µm

Figure 13. Microphotographs of Anydrite cement in Quirk Creek (Mississippian) and Duvernay (Devonian). (A) Q2: pore filling anhydrite cement postdating calcite, (B) Q3: pore filling anhydrite cement postdating medium crystalline anhedral to subhedral dolomite, (C) D5: Anhydrite cement postdating pore filling calcite cement , (D) D8: Anhydrite cement postdating blocky calcite cement

4.1.6 Silicification

Saddle dolomite cement is succeeded by quartz cement in some samples from Jedney field

(Devonian) and presents a late diagenetic event. Silica occurred as a pore filling that occur in the vuggy pores of dolomites.

4.2 Petrography of the Mississippian Formations

The main diagenetic processes included compaction, fracturing, calcite cementation, dolomitization, anhydrite cementation and silicification. Several types of fracture- and pore-filling cements (calcite, saddle dolomite and anhydrite) are recognized. Paragenetically, saddle dolomite occluded fractures and vugs, predated by early calcite cement but postdated by late calcite cement and anhydrite (Fig. 14). The host rock is characterized by fine (2 - 15 µm), medium (30-150 µm) and coarse (200-500 µm) crystalline euhedral to subhedral dolomite.

Diagenetic Process Early Late Fine crystalline matrix dolomite

Silicification

Medium crystalline matrix dolomite Coarse crystalline dolomite

Early pore filling equant calcite cement Early fracture filling calcite cement Mechanical compaction Chemical Compaction Pervasive dolomite Pore filling saddle dolomite Fracture filling saddle dolomite Late fracture filling calcite cement Late pore filling blocky calcite cement Anhydrite Figure 14. Paragenetic sequence of the Mississippian Formations

4.2.1 Compaction

Mechanical Compaction

The Mississippian formations were characterized by mechanical compaction features similar to the Devonian strata, which include grain fractures and tighter grain packing prior to cementation causing a reduction in porosity (Fig.15). The Upper Debolt Formation is substantially brecciated and White (1995) relate it to a faulting and fracturing mechanism occurring late in the burial history based on that saddle dolomite occludes fractures and vugs.

Chemical Compaction:

Dissolution seams and stylolites are the common features of chemical compaction in the

Mississippian formations. Dissolution seams in the studied Mississippian fields formed after matrix dolomites and early calcite cement but was postdated by late calcite cement. Stylolites in the studied fields represent a late diagenetic event postdating late calcite cement but also occasionally formed prior to late calcite cement and saddle dolomite (Fig 15).

Figure 15. Mechanical and chemical compaction features (A) 14-7 (Sikanni): 1- compaction (peloids) 2- dissolution 3-caclite cementation 4- fracturing (B) 14-8 (Sikanni): stylolites crosscutting skeletal components (peloids) and calcite cement

4.2.2 Fracturing

Two generations of fractures are observed in the Mississippian Formations. The first generation represents subvertical fractures (0.5-2cm) filled with early calcite cement and occluded by saddle dolomite. The second generation represents unfilled horizontal to subvertical fractures (0.5-3cm) crosscut by late calcite cement (Fig. 7D, 7E, and 7F).

4.2.3 Calcite Cementation

Two types of calcite cements were observed in the Mississippian samples: pore filling and fracture filling ranging in size from 30 to 1000µm (Figure 8). Pore filling calcite cement occur in

3 types: bladed-prismatic, blocky, and equant calcite spar cement. Bladed-prismatic calcite occurs in cavities and as pore filling cement in corals and stromatoporoids, ranging in size from 50 to 300

µm, and is characterized by elongate crystals. Blocky calcite (50 to 500 µm) cement is present in dolomitized wackestones filling pores left by dissolution of grains including corals, foraminifera and ooids where they have entirely filled the interparticle porosity. Equant calcite spar cement filled pores in brachiopods and gastropods along with occluding matrix and intraparticle porosity in corals and stromatoporoids , ranging in size from 30 to 1000µm. Pore filling calcite cement displayed a homogenous dull red color under CL (Fig. 8B).

Fracture filling calcite cement ranges in shape from euhedral to subhedral with 50 to 300 µm sized crystals and is non luminescent under CL. The first generation of subvertical fractures crosscut the undolomitized limestone and are occluded by early calcite cement. The Second generation of horizontal to subvertical fractures crosscut early calcite cement and saddle dolomite and are crosscut by stylolites and occluded by late calcite cement. Pore filling blocky late calcite cement postdated fracture filling calcite and formed after the pore filling saddle dolomite cement.

4.2.4 Dolomitization

Five main types of dolomite are documented in the Mississippian formations (Figs. 10 and

16): (1) fine crystalline matrix dolomite (FCMD) consists of euhedral to subhedral and anhedral crystals, ranges in size from 4 to 15 µm, occurring as a host rock and is characterized by dark red color under CL.; (2) medium crystalline matrix dolomite (MCMD) consists of euhedral to subhedral and anhedral crystals, ranges in size from 20 to 150 µm occurring as a host rock. Matrix dolomite replaces fossil fragments as well as matrix /cement and represents an early diagenetic event. Based on petrographic observations, precipitation of matrix dolomite occurred prior to mechanical and early chemical compaction (Figs. 16C and 16E); (3) coarse crystalline dolomite

(CCD) ranged in size from 200 to 500 µm, consisted of subhedral to anhedral crystals and displayed a dull red luminescent cores and bright red rims under CL. Based on Folk’s (1987) white card technique, CCD completely replaced the limestone host rock as was indicated by the presence of allochem ghosts (White, 1995) ; (4) pervasive dolomite (PD) is fabric destructive (dolomitized skeletal grains), ranges in size from 50 to 250 µm, displays a dull brownish red color with bright red rims under CL and replaces mud and fossil components. PD postdates early calcite cement and

FCMD and MCMD whereas it predates saddle dolomite and late calcite cement. PD is concentrated in the Turner Valley Formation (Quirk Creek), whereas CCD is concentrated in the

Upper Debolt Formation (Sikanni) and is characterized by larger grain size (200 to 500 µm) and

(5) saddle dolomite (SD) cement which occurs as pore filling with crystal sizes ranging from 20 to 100 µm and as fracture filling ranges in size from 50 to 500 µm. Large crystal size, sweeping extinction and curved crystal faces are the main characteristics of saddle dolomite. SD cement postdated early calcite cement and medium crystalline dolomite and is succeeded by late calcite cement. Microscopic examination shows that SD exhibits oscillatory zonation of dull to bright red

colors with dark red rims under CL. SD is crosscut by stylolites in Sikanni and Duvernay and was postdating stylolitization in Hamburg and Quirk Creek.

A B SD

50µm 50µm

C D

50µm 50µm

50µm

Figure 16. Photomicrograph of Mississippian Saddle dolomite cement. (A)Q4 showing pore filling calcite cement postdating anhydrite and pore filling saddle dolomite cement, (B) 14-12-16

QC showing pore filling saddle dolomite cement postdating planar subhedral to euhedral medium crystalline matrix dolomite, (C) 14-12-18 QC showing saddle dolomite postdating fine crystalline matrix dolomite, (D) 32-9 Sikanni showing saddle dolomite postdating calcite, (E) 32-10 Sikanni fracture filling saddle dolomite cement crosscutting fine crystalline matrix dolomite

4.2.5Anhydrite cementation

Anhydrite cement in the Mississippian fields occurs as a late stage diagenetic mineral phase

(Fig. 13). Two main types of anhydrite cement are identified: a pore filling (20-150 µm), and a fracture filling (50-150 µm). It commonly postdates fracture/ pore filling calcite and saddle dolomite cement and occasionally predates SD. Under CL anhydrite is non luminescent with a dark red color.

4.2.6 Silicification

Microcrystalline quartz in the Upper Debolt Formation (Sikanni) replaces fine crystalline matrix dolomite and calcite cement and ranged in size from 5 to 25 µm. Silicification represents an early diagenetic event where it is postdated by saddle dolomite and late calcite cement.

4.3 Geochemistry of the Devonian and Mississippian Formations

4.3.1 Oxygen and Carbon Isotopes

The data in this section includes results from previous studies (Al-Aasm, 1996; Clarke,

1998; White, 1995; Lu, 1993) combined with new additional data from this study marked by an asterisk in the appendix section. The δ18O isotopic values for the Devonian and Mississippian matrix dolomite (MD) range from -13.25 to -6.24‰ (average -10.87‰ ) and -10.03 to -3.8‰

(average -7.11‰), respectively. δ13C values range from 0.20 to 3.20 ‰ and 2.55 to 3.99‰ VPDB for the Devonian and Mississippian MD, respectively (n=30; Fig. 19 and Table 2).

The δ18O isotopic values for the Devonian and Mississippian pervasive dolomite (PD) range from -12.71 to -6.23 ‰ (average -10.14‰ ) and -5.46 to -1.11‰ (average -3.66 ‰),

respectively. δ13C values range from -0.02 to 3.50 ‰ and 0.85 to 3.52‰ VPDB for the Devonian and Mississippian PD, respectively (n=30; Fig. 19 and Table 2).

The δ18O isotopic values for the Devonian and Mississippian saddle dolomite (SD) range from -14.6 to -5.58 ‰ (average -12.2 ‰) and -10.8 to -7.8 ‰ (average -9.05 ‰) VPDB, respectively. δ13C values range from -2.08 to 3.16‰ (average 1.40 ‰) and -1.99 to 3.75 ‰

(average 2.36 ‰)VPDB for the Devonian and Mississippian SD respectively (n= 68; Fig. 18 and

Table2).

Fifty one samples from the studied fields were microsampled for calcitic components and showed δ18O values ranging from -14.80 to -5.52 (average -10.3 ‰) and -13.71 to -5.56 ‰ VPDB

(average -9.82 ‰) for the Devonian and Mississippian calcite cement, respectively. As for the δ13C values, it ranges from -2.17 to 2.56‰ VPDB (average 0.82 ‰) and -12.69 to 2.72‰

VPDB(average -3.96 ‰) for the above age groups, respectively. The summary of δ18O and δ13C results for dolomite types and calcite are presented in Figures 17 to 24 and Tables 2 and 3.

Sikanni Quirk Creek Hamburg 5 Jedney Duvernay 4 Middle Devonian Marine Dolomite

3 Mississippian Marine Dolomite

C (VPDB)C



-16 -14 -12 -10 -8 -6 -4 -2 2 4

18  O (VPDB) -1

-2

-3

Figure 17. δ18O vs δ13C values for saddle dolomite in the studied fields. The boxes represent δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989). Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)

Mississippian Devonian 5

Middle Devonian Marine Dolomite 4

3 Mississippian Marine Dolomite

C (VPDB)C



-16 -14 -12 -10 -8 -6 -4 -2 2 4 18  O (VPDB) -1

-2

-3

Figure 18. δ18O vs δ13Cfor saddle dolomite in the studied fields by Age. The box represents δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)

SD(Mississippian) SD(Devonian) MD(Mississippian) MD(Devonian) 5 PD(Mississippian) PD(Devonian)

3 Mississippian Marine Dolomite

Middle Devonian Marine Dolomite

-16 -14 -12 -10 -8 -6 -4 -2 2 4

18  O (VPDB) -1

-2 (VPDB)C



-3

Figure 19. δ18O vs δ13Cfor saddle matrix and pervasive dolomite in the studied fields by age. The box represents δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)

SD(Mississippian) SD(Devonian) MD(Mississippian) 5 MD (Devonian) Middle Devonian Marine Dolomite

Mississippian Marine Dolomite 2

-16 -14 -12 -10 -8 -6 -4 -2 2 4

18  O (VPDB) -1

-2 (VPDB)C



-3

Figure 20. δ18O vs δ13C for saddle and matrix dolomite in the studied fields by age. The box represents δ18O and δ13C values for Mississippian and Devonian marine dolomites (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al- Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993)

PFBC (Quirk Creek) FFC(Quirk Creek) PFEC(Quirk Creek) PFPC(Quirk Creek) 6 PFCS(Quirk Creek) PFCS(Hamburg) Mississippian Marine Calcite PFBC(Hamburg) Middle Devonian Marine Calcite 4 FFC(Duvernay) PFBC(Duvernay) LFFC(Sikanni) 2 EFFC(Sikanni) 18  O (VPDB)

-16 -14 -12 -10 -8 -6 -4 -2 2 4 -2

-4

C (VPDB)C

-6 

-8

-10

-12

-14

PFBC(Mississippian) PFBC(Devonian) FFC(Mississippian) FFC(Devonian) 6 PFCS (Mississippian) PFCS(Devonian) Mississippian Marine Calcite Middle Devonian Marine Calcite 4

-16 -14 -12 -10 -8 -6 -4 -2 2 4 18  O (VPDB) -2

-4

-6

C (VPDB)C

13 -8 

-10

-12

-14

Figure 22. δ18O vs δ13C for the calcite cement types in the studied fields by age. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993).

PFC(Mississippian) PFC(Devonian) 6 FFC(Mississippian) FFC(Devonian) Mississippian Marine Calcite Middle Devonian Marine Calcite 4

2 18  O (VPDB)

-16 -14 -12 -10 -8 -6 -4 -2 2 4 -2

-4

-6 (VPDB)C

 -8

-10

-12

-14

Figure 23. δ18O vs δ13C for fracture and pore filling calcite cement in the studied fields by age. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al- Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993).

Mississippian Devonian 6 Mississippian Marine Calcite Middle Devonian Marine Calcite 4

-16 -14 -12 -10 -8 -6 -4 -2 2 4 18  O (VPDB) -2

-4

-6 (VPDB)C

 -8

-10

-12

-14

Figure 24. δ18O vs δ13C of calcite cement in the studied fields by age. The box represent δ18O and δ13C values for Mississippian and Devonian calcite (Banner and Hanson, 1990; Hurley and Lohmann, 1989).Additional data were taken from previous studies (Al Aasm, 1996; Clarke, 1998; White, 1995; Lu, 1993). 4.3.2 Strontium Isotopes

The Sr isotopic composition of fracture/pore filling calcite cement varied from 0.708102 to

0.709630 and 0.709623 to 0.709743 for the Devonian and Mississippian carbonates, respectively

(Fig. 25). Samples of matrix dolomite from the Devonian and Mississippian carbonates range from

0.71002 to 0.71004 and 0.708491 to 0.70913, respectively. Saddle dolomite has 87Sr/86Sr values ranging from 0.708626 to 0.713480 and 0.708591 to 0.709975 for the Devonian and Mississippian carbonates, respectively (Figs. 26 and 27).

Mississippian Seawater

Middle Devonian Seawater

Figure 25. 87Sr/86Sr and δ18O isotopic compositions for calcite phases in the studied fields by age. The boxes represent Middle Devonian seawater (Denison et al., 1997; Veizer et al., 1999) and 87Sr/86Sr and δ18O values for Mississippian seawater (Denison et al., 1994; Banner & Hanson, 1990).

Mississippian Seawater

Middle Devonian Seawater

Figure 26. 87Sr/86Sr and δ18O isotopic compositions for dolomites in the studied carbonates by fields. The boxes represent Middle Devonian seawater (Denison et al., 1997; Veizer et al., 1999) and 87Sr/86Sr and δ18O values for Mississippian seawater (Denison et al., 1994; Banner & Hanson, 1990).

Mississippian Seawater

Middle Devonian Seawater

Figure 27. 87Sr/86Sr and δ18O isotopic compositions for dolomites in the studied fields by age. The boxes represent Middle Devonian seawater (Denison et al., 1997; Veizer et al., 1999) and 87Sr/86Sr and δ18O values for Mississippian seawater (Denison et al., 1994; Banner & Hanson, 1990).

4.4 Fluid Inclusion results of the Devonian and Mississippian Formations

The results in this section are taken from previous studies (Al-Aasm, 1996; Clarke, 1998; White,

1995) combined with new additional data from this study. Current results for saddle dolomite and calcite are shown in the appendix section (Duvernay and Quirk Creek results are from the current study). Microthermometric measurements were performed on 66 primary fluid inclusions in selected carbonate samples from the Devonian and Mississippian carbonates encompassing saddle dolomite (n=45) and calcite (n=21). The inclusions are two phase (liquid rich with vapor bubble) and one phase ranging in shape from circular to irregular and in size from less than 1 µm to 5 µm in diameter (Fig. 28). The reported measurements of melting (Tm) and homogenization temperatures (Th) are from two phase liquid-vapor inclusions from saddle dolomite and calcite.

Hydrocarbon fluid inclusions were not identified in the selected samples from the studied formations. A summary of the fluid inclusion results is presented in Tables 4 and 5.

Fluid inclusion data of saddle dolomites varied from Th: 125-191.7°C (average 158.3°C), 9.2 to

24.7 wt% NaCl (average: 17.3wt. % NaCl) and Th: 87.6-214.2 °C (average 136.3°C), 2.0 to 13.2 wt% NaCl (average: 9.6 wt. % NaCl) for the Devonian and Mississippian samples, respectively.

As for calcite it ranges from Th: 96-127°C (average 110.1°C), 19.8 to 24.6 wt. % NaCl (average:

22.8 wt. % NaCl) and Th: 117.3-196.4 °C (average 145.6°C), 0 to 22.5 wt. % NaCl (average: 1.3 wt. % NaCl) for the above age groups, respectively (Figs 29 to 36).

A B

20mm 10mm m m

D C

5mm 5mm

E F

10mm 5mm m

Figure 28. Fluid Incusions from Quirk Creek: (A &B) Fluid inclusion assemblage in saddle dolomite under 10x & 40x, (B & C): shows six two-phase primary fluid inclusions (liquid rich with vapor bubble) in saddle dolomite ranging in shape from elongate to subcircular and in size from 2 to 6 µm under 100x, (E ): Fluid inclusion assemblage in blocky calcite under 40x, (F): two phase fluid inclusion in blocky calcite under 100x

Sikanni Hamburg 26 Jedney 24 Quirk Creek Duvernay 22

Salinity wt.%Salinity NaCl 8

80 90 100 110 120 130 140 150 160 170 180 190 200 210 T (°C) h

Figure 29. Th vs. salinity of saddle dolomite by fields. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995).

26 Mississippian 24 Devonian

Salinity wt.% NaCl Salinitywt.% 8

80 90 100 110 120 130 140 150 160 170 180 190 200 210 T (°C) H

Figure 30. Th vs. salinity of saddle dolomite by age. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995).

Sikanni 26 Hamburg 24 Quirk Creek 22 Duvernay 20 18 16 14 12 10 8 6

SalinityNaCl wt.% 4 2 0 -2 -4

80 90 100 110 120 130 140 150 160 170 180 190 200 210 T (°C) H

Figure 31. Th vs. salinity of calcite cement by fields Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995).

26 Mississippian 24 Devonian 22 20 18 16 14 12 10 8 6

SalinityNaCl wt.% 4 2 0 -2 -4

80 90 100 110 120 130 140 150 160 170 180 190 200 210 T (°C) H

Figure 32. Th vs. salinity of calcite cement by age. Additional data were taken from previous studies cf. (Al-Aasm, 1996; Clarke, 1998; White, 1995).

8 Mississippian Devonian 7

Frequency

80 100 120 140 160 180 200 220 T (°C) h

10 Mississippian Devonian 9

Frequency 3

5 10 15 20 25 30 Salinity wt.%NaCl

Figure 34. Histogram showing the frequency distribution of salinity for fluid inclusions from saddle dolomite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995).

6 Mississippian Devonian

Frequency 2

80 100 120 140 160 180 200 220 T (°C) H

Figure 35. Histogram showing frequency distribution of Th for fluid inclusions from calcite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995).

Mississippian 12 Devonian

Frequency 4

-5 0 5 10 15 20 25 30 Salinity wt.%NaCl

Figure 36. Histogram showing frequency distribution of salinity for fluid inclusions from calcite. Additional data were taken from previous studies (cf. Al-Aasm, 1996; Clarke, 1998; White, 1995).

Chapter 5 Discussion

The integrated core, petrographic, stable and Sr isotopes, and fluid-inclusion microthermometry provided clues to the diagenetic conditions encountered that controlled the origin, geochemical composition of the diagenetic fluids, which were responsible for fracture diagenesis, dolomitization and for cementation by dolomite and calcite of the Devonian and Mississippian carbonates in WCSB.

5.1 Constraints from petrography

In the Devonian formations, calcite cementation occurred during early and late diagenetic stages where it commenced in shallow marine environments and continued through to deep burial environments (Fig. 6). Calcite spar cement can form in either meteoric or burial settings (e.g.

Tucker and Wright, 1990). Petrographic evidence including precipitation after grain micritization and healing of broken grains suggests that calcite spar cement in the Duvernay and Slave Point formations precipitated in a burial environment (e.g. James and Jones, 2016). Blocky calcite in the

Devonian occurred as a void filling cement and represents a late diagenetic event based on petrographic observations such as filling the last generation of fractures and postdating saddle dolomite cement. The formation of fine and medium crystalline dolomites occurred prior to chemical compaction (Fig. 11E) based on petrographic evidence including the deflection of dissolution seams around dolomite crystals and its occurrence prior to stylolitization (predating chemical compaction features), hence indicating precipitation during shallow burial (early

diagenetic phase). Pervasive dolomite (PD) postdated early calcite cement and matrix dolomite

(MD), replaced mud and fossil components, and occurred within pressure solution seams; therefore, based on such petrographic evidence PD is likely formed in a shallow burial setting.

Qing and Mountjoy (1994) suggested that dissolution of high magnesium calcite and magnesium remobilized by pressure solution of older dolomite could represent the sources of magnesium, where stylolites would act as conduits for the diagenetic fluids. Petrographic evidence including occlusion of the second generation of fractures combined with its formation after pervasive dolomite and fine and medium crystalline matrix dolomite (Fig. 12B, 12C and 12D) suggest that saddle dolomite (SD) represents a later diagenetic event and is possibly of a shallow to intermediate burial origin.

Calcite cementation in the Mississippian formations represents an early and late stage diagenetic event where it commenced in shallow marine environments and continued through to deep burial realms. Calcite spar cement can form in meteoric and shallow burial environments (e.g. Flugel,

2004). Calcite spar cement from the Blueberry field (Upper Debolt Formation) formed from meteoric fluids (Durocher and Al-Aasm, 1997). Petrographic evidence including the healing of broken fossil fragments subjected to mechanical compaction indicate that calcite spar cement precipitated in a shallow burial environment (Foreman, 1989). Bladed calcite cement occurred in cavities and as pore filling cement in corals and stromatoporoids, and was succeeded by calcite spar cement indicating an early burial environment of formation (Choquette and James, 1987).

Early pore filling blocky calcite cement displayed a non-luminescent CL, was postdated by pervasive dolomite and entirely filled the interparticle porosity indicating precipitation in a shallow burial environment. Petrographic evidence including non-luminescent CL (related to the reducing nature of fluids) and occlusion of early fractures and stylolites suggest that this type of cement

formed in a shallow burial environment (Tucker and Wright, 1990, Al-Aasm and Vernon, 2007).

Very low Mn2+ (< 25 ppm) and Fe2+ contents in an oxidized solution is also indicative of non- luminescence (Budd et al., 2000). Late fracture and pore filling calcite cement formed in a late burial environment as indicated by the petrographic evidence which included: dull CL, occlusion of fractures and pores and formation after saddle dolomite.

Fine crystalline matrix dolomite (FCMD) formed prior to mechanical compaction and therefore represents an early diagenetic event. Saller (1984) suggested that a possible mechanism for dolomite formation is through tidal pumping of large volumes of seawater into sediments.

Durocher and Al-Aasm (1997) suggested a pre-compaction origin of early matrix dolomite in the

Upper Debolt Formation (Blueberry Field) possibly from marine fluids. A shallow burial setting prior to significant compaction is also suggested for the Lower Ordovician fine crystalline dolomite in eastern Laurentia (Azomani et al., 2013). Al-Aasm and Packard (2000) proposed a very shallow burial environment of deposition for the early formed matrix dolomite in the Upper

Debolt Formation of the Dunvegan Field (NW Alberta) possibly from dolomitizing fluids associated with Mississippian seawater that were dense Mg-rich brines. Therefore, the most relevant model to explain the formation of FCMD is the shallow burial model by marine fluids.

Medium crystalline matrix dolomite (MCMD) formed after mechanical and during early chemical compaction based on petrographic observations in the Mississippian formations and hence represents an intermediate diagenetic event. Al-Aasm and Raymus (2007) suggested the reflux brine model for the formation of fine to medium crystalline matrix dolomite in the Devonian

Crossfield reservoir in Alberta. The petrographic evidence that supported their conclusion includes non-luminescent to very dully luminescent matrix dolomite and that the MD is crosscut by dissolution seams combined with the significant preservation of the origin fabrics in MD. The

burial compaction model is the most relevant model to describe the formation of matrix dolomite

(MD) as it developed due to increasing compaction along dissolution seams with crystal size range from 20 to 150 µm (Wanless, 1979). Coarse crystalline dolomite (CCD) formed during intermediate burial depths possibly by hydrothermal fluids as suggested by petrographic evidence, such presence of brecciated fragments of CCD , the pervasive dolomitization of limestone and the abrupt transition between limestone and dolomite beds due to porosity and permeability changes along with the proximity to crosscutting faults and fractures (Stoakes,1987). The above characteristics and features are also observed in the Upper Wabamun Formation (Packard et al.,

1990), Black River and Trenton Formations of the Michigan Basin (Coniglio et al., 1994) and

Presqu’ille Barrier, NWT (Qing and Mountjoy, 1994). Pervasive dolomite (PD) postdated early calcite cement and matrix dolomite as observed from petrographic evidence. Hardie (1987) reported that up to date no single model for massive dolomitization has been generally accepted.

The reflux brines model was proposed by Murray and Lucia (1967) and the burial compaction model was suggested by Illing (1959) to account for the massive dolomitization in the Turner

Valley carbonates (Quirk Creek). Land (1985) reported that no large scale source of Mg is available through the burial compaction model and hence the mechanism that provided Mg for pervasive dolomitization is still problematic. Lu (1993) suggested that PD formed through a combination of burial (shallow to intermediate) and mixing zone environments. Pervasive dolomite (PD) is present in many Mississippian fields from Western Canada Sedimentary Basin including Sikanni, Dunvegan and Blueberry (Upper Debolt Formation) Quirk Creek and Moose

Mountain (Turner Valley Formation), and the Sylvan Lake (Pekisko Formation). Al-Aasm (2000) suggested that PD in the Sylvan Lake, Quirk Creek and Blueberry fields formed during shallow burial whereas it formed during intermediate burial in Sikanni and Moose Mountain. Petrographic

and isotopic evidence pointed towards recrystallization of matrix dolomite commencing early in the digenetic history of the Mississippian carbonate and continuing through burial. Changes in burial conditions and fluid chemistry are reflected due to variations in geochemical, isotopic and crystallographic signatures. No evidence of meteoric exposure exist in Sikanni probably since it was deposited in the deeper parts of the basin (cf. White and Al-Aasm, 1997). Al-Aasm (2000) concluded that in some carbonate reservoirs (e.g., Upper Debolt Formation from the Dunvegan

Field), recrystallization of microcrystalline dolomites initiated in marine pore fluid contrary to others (e.g., Pekisko dolomites) where it commenced in meteoric-dominated system.

Recrystallization of MD to PD occurred during burial conditions from basinal and hydrothermal fluids. Therefore, a shallow to intermediate burial model and mixing zone environment is proposed here for the formation of pervasive dolomite. Al-Aasm and Vernon (2007) interpreted the saddle dolomite from the Mississippian Pekisko Formation to be of a deep burial origin as it postdated the pervasive dolomite (which formed during shallow burial) and chemical compaction features.

Petrographic evidence including the occlusion of late fractures and vugs, replacement of early calcite cement and formation after medium crystalline matrix dolomite and pervasive dolomite indicates that saddle dolomite (SD) precipitated in a shallow to intermediate burial environment.

5.2 Constraints from isotope analysis of saddle dolomite and calcite

Given the objectives of this research, the main focus of the isotopic analysis is on fracture-related and pore filling saddle dolomite. Qing and Mountjoy (1989) along with Wong and Oldershaw

(1981) proposed that fluids of burial origin precipitated the saddle dolomite in the Devonian reefs of western Canada. Chemical compaction and thermochemical sulfate reduction were suggested by Machel (1987) to account for the saddle dolomite formation in the Nisku reefs. Al-Aasm (2003) suggested that the formation of saddle dolomite in the Devonian and Mississippian formations

from Western Canada Sedimentary Basin occurred as a result of hydrothermal fluid flow along faults and fractures associated with deformation during the late Devonian and Mississippian. Ma et al. (2006) proposed based on numerical modelling that hydrothermal fluid flow during the Antler

Orogeny (late Devonian and early Mississippian) are responsible for saddle dolomite formation in the Upper Devonian Wabamun Group. Examples of hydrothermal dolomites include the Presqu'ile dolomite (Qing and Mountjoy, 1994), the Manetoe dolomite (Morrow et al., 1986), dolomites from the Keg River Formation (Aulstead and Spencer, 1985; Qing and Mountjoy, 1989), Slave Point

Formation (Clarke and Al-Aasm, 1998) and the Wabamun dolomites (Packard et al., 1990;

Packard et al, 2001). Lonnee and Al-Aasm (2000) proposed that the precipitation of saddle dolomite in the Middle Devonian Sulphur Point Formation, Rainbow South Field, Alberta, involved a hot hydrothermal fluid based on geochemical and petrographic evidence.

The δ18O isotopic compositions from the Devonian Slave Point Formation (Hamburg Field) in

Northwestern Alberta varied from -13.95 to -11.97 ‰ VPDB and δ13C varied from 1.19 to 3.2 ‰

VPDB (Fig.17) suggesting precipitation by warm fluids. 87Sr/86Sr isotopic ratios (Fig. 26) were more radiogenic than the Devonian marine values (0.7078 to 0.70803) and ranged from 0.70860 to 0.71035, excluding evaporites and marine carbonates as the radiogenic 87Sr source. As for SD from the Devonian Slave Point Formation (Jedney field) in Northeast British Columbia, the burial model alone cannot account for the highly negative shift in oxygen isotope value (-14.62 ‰ VPDB;

Fig. 17) due to the fact that the formation of saddle dolomite occurred prior to significant chemical compaction and the allochtonous origin of the fluid (radiogenic Sr), hence, suggesting the presence of a hot hydrothermal fluid (cf. Qing and Mountjoy, 1994; Al-Aasm, 1996). Oxygen isotopic values (-11.78 to -5.58 ‰ VPDB) and δ13C values (-2.08 to 3.16‰ VPDB) from Duvernay (Fig.

17) varied significantly from the Slave Point Formation(Hamburg and Jedney) suggesting spatial

variability of values with more enriched oxygen values and more depleted carbon isotope values towards central Alberta (Figs.39 and 40). Therefore, a burial model characterizes the formation of

SD from Duvernay due to the depletion in oxygen isotopic values relative to the Middle Devonian marine dolomite (Fig. 17) and the depletion in δ13C values provide an evidence of thermochemical sulfate reduction (Machel, 1998, Wendte et al., 1998).

The δ18O and δ13C isotopic values of SD from Sikanni (Mississippian) ranged from -10.8 to -7.8

‰ VPDB and 1.13 to 3.75 ‰ VPDB (Fig. 17), respectively with enriched 87Sr/86Sr isotopic ratios

(0.708591 to 0.709975; Fig. 26), hence suggesting a burial origin possibly by hydrothermal fluids.

Saddle dolomites (SD) from the Mississippian Pekisko Formation are characterized by negative oxygen isotopic values ranging from -5 to -8 ‰ VPDB which are similar to SD δ18O values from the Devonian Wabamun Group of this area (cf. Packard et al., 1990) and δ13C values ranging from

1.13 to 3.75 ‰ VPDB (Al-Aasm and Vernon, 2007).The above oxygen and carbon isotopic values are also comparable with the values from Sikanni but with more negative δ18O values. Isotope analysis was performed on only one saddle dolomite (SD) sample from Quirk Creek due to the sparse distribution and small size of SD within that field. SD had δ18O and δ13C isotopic values of -9.01 and -1.99 ‰ VPDB also suggesting a burial origin. The depletion in δ13C isotopic values relative to Sikanni indicates spatial variability of these values towards the NW part of the basin.

In summary, the δ18O isotopic values for the Devonian saddle dolomite combined with enriched

87Sr/86Sr isotopic ratios show significant differences (Fig. 39) from the Mississippian saddle dolomite, which is characterized by less depleted δ18O isotopic values and less radiogenic 87Sr/86Sr isotopic ratios. These results suggest a possibility of two different hydrothermal pulses related to early and late tectonic events that affected the Western Canada Sedimentary Basin.

The δ18O isotopic values for calcite cement for both the Devonian and Mississippian age groups shows relatively depleted values (-14.80 to -5.52 ‰ VPDB) indicating a late burial environment of formation (Fig. 24). The δ13C isotopic values are more depleted in the Mississippian (-12.69 to

2.72‰ VPDB, average -3.96 ‰) relative to the Devonian (-2.17 to 2.56‰ VPDB, average 0.82

‰) suggesting an alternate source of carbon relative to the Mississippian marine calcite. Possible sources of negative carbon include: bacterial oxidation or sulfate reduction if δ13C isotopic values range from -6 to -15 ‰ VPDB and thermal decarboxylation in the deep surface if δ13C isotopic values range from -10 to -25 ‰ VPDB (e.g. James and Jones, 2016). Carbonates stabilized under meteoric water have δ13C values ranging from +2 to -10‰ VPDB (Moore, 1989). Based on the values above the depletion in δ13C values may be the result thermochemical sulfate reduction.

James and Choquette (1984) and Allen and Mathews (1982) suggested that moderately low δ13C compositions are associated with the dissolution of marine limestones and sediments and subsequent precipitation of calcite cement in the vadose and shallow phreatic zones due to soil weathering and carbonate mineral stabilization, hence suggesting a shallow burial setting. The

δ13C isotopic values for pore filling calcite (PFC) cement in the Mississippian and fracture filling calcite (FFC) cement from the Devonian shows a depleted range relative to the postulated values for carbonate deposited in equilibrium with Mississippian and Devonian seawater (Hurley and

Lohmann,1989; Banner and Hanson, 1990; Figure 23) possibly due to TSR.

5.3 Nature of the diagenetic fluids involved in precipitation of fracture-related saddle dolomite

2+ - Morrow (1990) stated that supply of Mg and CO3 , the delivery mechanism and a dolomite construction site are the basic factors for dolomitization to occur. According to Qing and Mountjoy

(1994) high Mg- calcites, Mg absorbed clay and organic matter, structure bond Mg2+ in clay and

organic matter, remobilization of Mg2+ through pressure solution of older dolomites, formation waters and injection of fluids through fractures and faults are the basic sources of magnesium. In the Paleozoic strata, the Mg2+ content of present formation waters in WCSB is three times that of seawater and higher contents might have occurred in the past (Qing and Mountjoy, 1994).

Therefore Mg2+ could be provided through ancient formation waters enriched in Mg2+ if there was a sufficient driving mechanism to maintain fluid flow overlong period of time. Deep basinal brines injected through faults and fractures could provide another source for Mg2+ (Qing and Mountjoy,

1994). In this study, a hydrothermal basinal brine is the most applicable fluid source with slightly

(Mississippian) to highly (Devonian) saline values.

Fluid inclusion data of saddle dolomites varied from Th: 125-191.78°C (average 158.3°C) and 9.28 to 24.7 wt% NaCl (average: 17.3wt. % NaCl) for the Devonian carbonates, suggesting that the precipitation of saddle dolomite (SD) formed from a hot saline brines. Fluid inclusion data of saddle dolomites varied from Th: 87.69-214.25 °C (average 136.3°C), 2.0 to 13.2 wt% NaCl

(average: 9.6 wt. % NaCl) for the Mississippian fields, also suggesting precipitation of SD by a relatively hot but less saline brine, which is indicative of hydrothermal activity as well (Searl,

1989). The Devonian saddle dolomites are characterized by higher homogenization temperature and salinity relative to the Mississippian saddle dolomites (Fig. 30). Al-Aasm (2003) classified the homogenization temperature for Devonian and Mississippian saddle dolomite (SD) in WCSB into

3 groups: a lower range (ca. 80-120 °C), a medium range (120-160 °C), and a higher range >160

°C. Group one belonged to Devonian Wabamun Group and some samples from the Mississippian

Upper Debolt Formation. Group two characterize SD from the Slave Point Formation, Wabamun of Parkland field and some samples from the Upper Debolt Formation. Group three belonged to the Slave Point Formation from Jedney and Sulphur Point Formation from Rainbow South. Two

groups were suggested for the salinity values measured from fluid inclusions in SD: group one from Parkland, Tangent and Hamburg fields were characterized by high salinity values (>20 wt.

% NaCl) and group two from Jedney, Sikanni and Rainbow South were characterized by lower salinity values. The above data is consistent with the data from this study.

Figure 29 demonstrates that saddle dolomite from the Slave Point Formation ( Hamburg Field) have higher salinity relative to the ones from Slave Point Formation (Jedney Field) , indicating a highly saline brine source possibly due to spatial variability (see section 5.5) within the Devonian fields (Fig. 41). Fluids associated with the Laramide Orogeny tend to be mixed brines and meteoric waters with a salinity range of 0-10 wt. % NaCl (Nesbitt and Muehlenbachs, 1994).Hence, the highly saline values from Hamburg (North Western Alberta) suggest its association with the

Antlers Orogeny (Late Devonian and Early Mississippian) contrary to Jedney (North East British

Columbia) that is related to hydrothermal fluid flow that occurred during the Laramide Orogeny

(Late Cretaceous to Early Tertiary). Figures 33 and 34 show a clear bimodal distribution of the salinity and homogenization temperatures of SD where a peak of Th= 120 °C and 160 °C with a salinity of 10 and 25 wt. % NaCl characterized the Mississippian and Devonian SD, respectively.

Therefore, a divergent fluid source (Figs. 41 and 42) is responsible for the precipitation of SD in the above age groups where SD from Sikanni and Quirk Creek (Mississippian) and Jedney

(Devonian) is associated with upward and/or lateral movement of hydrothermal fluids charged during the Laramide Orogeny whereas Hamburg and Duvernay (Devonian) occurred during the late Devonian and early Mississippian (Antler Orogeny). 87Sr/86Sr isotopic ratios of the

Mississippian and Devonian saddle dolomites are enriched relative to the Devonian and

Mississippian marine carbonates (Fig. 27), hence suggesting an enriched strontium fluid source

with two separate pulses of hydrothermal fluids given that the Devonian was characterized by more enriched 87Sr/86Sr isotopic ratios relative to the Mississippian.

Figure 37 shows the relationship between δ18O values for fluids, temperature and δ18O values for saddle dolomite and matrix dolomite. It shows that matrix dolomite formed at lower temperatures compared to saddle dolomite (SD), which is characterized by enriched δ18O fluid values forming at higher temperatures and are formed by later warmer fluids. A clear divergent fluid source is demonstrated where the Devonian SD formed by a warmer fluids at higher temperature compared to the Mississippian SD.

Dolomite -13 -9 -5 210 200 190 180 170 -9 -5 160 -1 150 Dev SD 140 130 Miss SD 120 110 -1 100 Middle 90 Devonian 80 70 Dolomite Miss MD 60 Temperature (˚C) Temperature 50 40 Mississippian 30 Marine 20 10 Dolomite 0 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 δ18O (SMOW)

Figure 37. Calculated oxygen isotopic composition of the dolomitization fluid from saddle dolomite (SD) and matrix dolomite (MD) (expressed in VSMOW). Fractionation equation that is used is from Land (1983).

Figure 38 shows the relationship between δ18O values for fluids, temperature and δ18O values for early equant calcite spar cement and late blocky calcite cement. It shows that the late fracture and pore filling blocky calcite cement from the Mississippian and Devonian formed at higher temperature and by warmer fluid relative to the early calcite spar cement. The Mississippian blocky calcite cement formed at higher temperatures compared to the Devonian indicating a divergence in the fluids origin.

Calcite -18 -14 -10 -6 190 180 170 160 -14 150 Late Devonian Calcite 140 -2 130 Late Devonian Calcite 120 110 100 Early Devonian Calcite 90 80 70

Temperature (˚C) Temperature 60 50 40 Miss. Calcite 30 Early Miss. Calcite 20 Middle Devonian 10 Calcite 0 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 δ18O (SMOW)

Figure 38. Fluid oxygen isotopic composition vs. formation temperature for calcite in the Mississippian and Devonian. Fractionation equation that is used is from Friedman and O'Neil (1977). Formation temperature for early Mississippian and Devonian calcite are estimated from Al-Aasm and Vernon (2007) and Clarke (1998).

The above data combined with the isotope analysis in the previous sections confirms that two different hydrothermal pulses related to early and late tectonic events affected the Western Canada

Sedimentary Basin.

5.4 Relationship between fracturing and tectonic events

The timing of saddle dolomite formation in the Devonian and Mississippian carbonates is discussed taking into account the relationship between fracturing and tectonic events in Western

Canada Sedimentary Basin. Diagenetic fluids responsible for hydrothermal dolomitization in the

Devonian were channeled through faults associated with tectonic events during burial. Packard et al. (1990; 2001), Kaufman et al. (1990), Nesbitt and Muehlenbachs (1995) and Ma et al., (2006) proposed that dolomitization in many regions from the Devonian was caused by the upward and lateral flow of warm hydrothermal fluids.

Tectonic compression and sedimentary loading in Western Canada Sedimentary Basin resulted in large scale fluid movement, which were confined to two main events since the deposition of the

Devonian strata: the Antler Orogeny between late Devonian and early Mississippian (Machel and

Cavell, 1999; Root, 2001) and the Columbian/ Laramide Orogenies between late Jurassic and early

Tertiary (Symons et al., 1999). The hydrothermal dolomitization of the Wabamun Group in the

Peace River Arch was suggested by Packard et al. (1990) to have occurred during a post Devonian, pre-Laramide hydrothermal event. Furthermore, Nesbitt and Muehlenbachs (1995) reported that a pre-Laramide hydrothermal event was attributed to the fluid origin of the Canadian Rockies through a west to east migration of warm saline fluids.

The timing of saddle dolomite precipitation is constrained using petrographic, geochemical and fluid inclusion data. The Devonian formations are characterized by enriched 87Sr/86Sr isotopic

ratios (0.708626 to 0.713480) and high salinities (9.28 to 24.7 wt% NaCl), which are consistent with the pre-Laramide fluid flow salinities range as suggested by Nesbitt and Muehlenbachs

(1994). Therefore, saddle dolomite precipitation occurred as a result of hydrothermal fluid flow along faults and fractures associated with the deformation during the Antlers Orogeny (late

Devonian and early Mississippian), with the exception of Jedney, based on the above petrographic and geochemical evidence. Petrographic evidence, such as formation of saddle dolomite that occludes fractures and predates stylolitization, which is an indicative of deep burial setting, also support an earlier shallow burial origin of saddle dolomite.

Extensive thrust faulting and folding resulted from the uplift of Western Canada Sedimentary

Basin that occurred during the Laramide Orogeny (Symons et al., 1999). Conduits for hydrothermal fluids were provided through the fractures and brecciation within rocks during this deformational event. In the Upper Debolt formation (Mississippian), coarse crystalline dolomite

(CCD) replaced the limestone during this time followed by precipitation of saddle dolomite (SD) in open fractures (White, 1995). δ18O and δ13C isotopic values combined with the 87Sr/86Sr values for the Mississippian SD (Table 2) do not match the expected Mississippian carbonate or seawater values (Banner and Hanson, 1990; Hurley and Lohmann, 1989, Figs. 18 and 27), indicating that

SD precipitation formed from fluids other than of marine parentage, possible hydrothermal saline brines associated with the Laramide Orogeny. Nesbitt and Muehlenbachs (1994) suggested that fluids associated with the Laramide Orogeny are of a mixed brine and meteoric water fluid origin, which are characterized by a salinity range of 0- 10 wt. % NaCl. The Mississippian formations were characterized by an average salinity of 9.6 wt. % NaCl, hence confirming an association of fractures and faults with deformation during the Laramide Orogeny (late Jurassic and early

Tertiary). In Summary, δ18O isotopic values combined with 87Sr/86Sr isotopic ratios and fluid

inclusion data show somewhat spatial variability existed within the Mississippian and Devonian fields whereby more depleted δ18O values, higher salinity and higher temperature are observed in saddle dolomite from the Devonian carbonates in the NE part of the basin compared to

Mississippian dolostones in the NW part.

5.5 Effect of fluid flow via fractures on reservoir characterization

Fractures in the above studied fields from the Devonian and Mississippian had a significant role in reservoir enhancement and channeling of the diagenetic fluids providing conduits for fluid movement involved in the precipitation of saddle dolomite as well as creating secondary porosity by leaching host limestones (Wagner, 1990). Lonergan et al. (2006) reported that a significant proportion of the world’s hydrocarbon reserves is contained within fractured reservoirs. Therefore, a better understanding of the fractures connectivity through advanced geological techniques for detecting fractures along with numerical and analogue modelling is necessary for an efficient development of these fractured reservoirs.

Wierzbicki et al., (2006) discussed the role of fractures in reservoir characterization of the Abenaki platform carbonates, Deep Panuke reservoir. They suggested that fractures delivered the diagenetic fluids capable of dissolving dolomites through movement into secondary pores; formed late-stage, pore filling calcite and dolomite cements (including saddle dolomites) which was delivered through fractures, and matrix permeabilities were significantly enhanced. Therefore, the overall permeability of the reservoir is highly affected by the fractures network and connectivity which consequently affects reservoir characterization.

In this study, faults and fractures developed during the Antler Orogeny in the Late Devonian and

Early Mississippian for the Devonian Formations (Slave Point and Duvernay) and later during the

Laramide Orogeny in the Late Cretaceous to Early Tertiary for the Mississippian Formations

(Upper Debolt and Turner Valley), acted as conduits for hydrothermal fluids. Therefore, fractures had a significant role in reservoir enhancement and channeling of the diagenetic fluids involved in saddle dolomite precipitation in Western Canada Sedimentary Basin.

Chapter 6 Conclusions

6.1 Conclusions

Core examinations, petrographic, geochemical (C-, O- and Sr-isotopes), and fluid-inclusion

micro-thermometric studies of calcite cement and dolomitization of the Devonian and

Mississippian carbonates in Alberta and BC, allow to conclude the following:

1. Petrographic evidence from the Devonian and Mississippian Formations, such as formation

of saddle dolomite that occludes fractures and predates stylolitization, is indicative of a

shallow to intermediate burial origin of saddle dolomite

2. The negative δ18O isotopic values combined with enriched 87Sr/86Sr isotopic ratios and high

homogenization temperatures from the Devonian and Mississippian saddle dolomite

indicate the presence of a hydrothermal fluid source

3. Oxygen isotopic and δ13C values from Duvernay varied significantly from the other

Devonian formations (in Hamburg and Jedney) suggesting spatial variability of values with

more enriched oxygen values and depleted carbon isotope values towards central Alberta.

Therefore, a burial model characterizes the formation of SD from Duvernay and the

depletion in δ13C values provides evidence of thermochemical sulfate reduction

4. Isotopic evidence indicates that the Devonian saddle dolomite shows significant

differences from the Mississippian saddle dolomite, which is characterized by less depleted

δ18O isotopic values and less radiogenic 87Sr/86Sr isotopic ratios. Hence, suggesting that

possibly two different hydrothermal pulses related to early (Antler) for the former and late

tectonic events (Laramide) for the latter affected the Western Canada Sedimentary Basin

5. Fluid inclusion data of saddle dolomites from the Devonian and Mississippian indicates

that the precipitation of saddle dolomite (SD) occurred from a warm highly to slightly

saline brine during burial.

6. The highly saline values of saddle dolomite from Hamburg (NW Alberta) suggest its

association with the Antlers Orogeny (late Devonian and early Mississippian) contrary to

Jedney (NE British Columbia) that is related to hydrothermal fluid flow that occurred

during the Laramide Orogeny.

7. Saddle dolomite precipitation from the Devonian fields occurred as a result of

hydrothermal fluid flow along faults and fractures associated with the deformation during

the Antlers Orogeny (Late Devonian and Early Mississippian) with the exception of

Jedney, differing from the Mississippian saddle dolomite precipitation which occurred later

during the Laramide Orogeny

8. The effect of compartmentalization of hydrothermal fluids in Western Canada Sedimentary

Basin is apparent through the geochemical and fluid inclusion data, which shows that

spatial variability exists within the Mississippian and Devonian fields whereby more

depleted δ18O values, higher salinity and higher temperature are observed in saddle

dolomite from the Devonian carbonates in the NE part of the basin compared to

Mississippian dolostones in the NW part

9. Fluid flow along fractures has a significant impact on diagenesis and reservoir quality of

dolomites

6.2 Future Work

This study used an integrated petrographic, geochemical and fluid inclusion analysis to quantify the type and nature of fluids that precipitated saddle dolomite and investigate the fluid compartmentalization of Devonian and Mississippian dolostones in Western Canada Sedimentary

Basin. To reach a more comprehensive understanding of the fluid evolution and fracture mineralization in the Devonian and Mississippian Formations in WCSB more sampling is needed to fill the gaps in the Devonian Duvernay Formation in Central Alberta. The section below represents an attempt to determine the spatial variability of isotopic signatures, salinities and homogenization temperatures of saddle dolomite in WCSB. Additional sampling from Alberta and

British Columbia is needed to produce more meaningful patterns in the below maps.

6.2.1 Temporal and spatial variability of isotopic signatures, salinities and homogenization temperatures of SD in the Devonian and Mississippian Formations

Devonian saddle dolomite (SD) from the Slave Point Formation in NE British Columbia (Jedney

Field) and NW Alberta (Hamburg Field) show a highly depleted range of oxygen isotopic values relative to the Mississippian Turner Valley Formation in SW Alberta (Quirk Creek Field) and

Upper Debolt Formation in NE British Columbia (Sikanni Field).The Devonian Duvernay

Formation in Central Alberta shows the least depleted oxygen isotopic values of SD (Fig.

39).Hence a less depleted trend in δ18O isotopic values is observed towards SW and central

Alberta. As mentioned earlier the highly negative oxygen isotopic values in the Devonian Slave

Point Formation relative to the Mississippian Turner Valley and Upper Debolt Formations is related to two pulses of hydrothermal fluid flow associated with early tectonic events (Antler) for the former and late tectonic events (Laramide) for the latter. The association of the Devonian

Duvernay Formation with the Antlers Orogeny is based on that its salinity values range (Fig. 42) does not coincide with the salinity range (0-10 wt. % NaC1 eq.) for fluids associated with the

Laramide Orogeny (Nesbitt and Muehlenbachs, 1994).

The carbon isotopic values of SD from the Mississippian Turner Valley Formation, SW Alberta

(Quirk Creek) are depleted relative the Mississippian Upper Debolt Formation in NE British

Columbia (Sikanni) indicating spatial variability within the Mississippian from NE British

Columbia to SW Alberta. The same relationship exist between the Devonian Jedney field (NE

British Columbia) opposed to the Devonian Hamburg and Duvernay fields in NW and Central

Alberta that are characterized with more enriched δ13C values relative to Jedney (Fig. 40). The depletion in carbon isotopic values is possibly due to thermochemical sulfate reduction as mentioned previously.

Saddle dolomite from the Devonian Slave Point Formation, Jedney Field in NE British Columbia has the highest homogenization temperature range followed by Devonian Slave Point Formation,

Hamburg field (NW Alberta) and Devonian Duvernay formation (Central Alberta) and the lowest

Th in the Mississippian Turner Valley Formation, Quirk Creek field (SW Alberta) and Upper

Debolt Formation, Sikanni field in NE British Columbia (Fig. 41, Table 4). As mentioned earlier the Devonian saddle dolomites are characterized by higher homogenization temperatures relative to the Mississippian saddle dolomites confirming that two separate pulses of hydrothermal fluids related to early (Antler) and late (Laramide) tectonic events affected WCSB. Al-Aasm (2003) and

White (1995) suggested that the Upper Debolt Formation, Sikanni field in NE British Columbia had a low range of homogenization temperatures and salinity values possibly related to the

Laramide Orogeny and that the higher temperatures in the Devonian formation were caused by the

upward and/or lateral movement of hydrothermal fluids charged during Late Devonian-Early

Mississippian time (Antler).

Salinity values for saddle dolomite from the Devonian Slave Point Formation in NW Alberta

(Hamburg Field) and Devonian Duvernay Formation in Central Alberta are significantly higher than the salinity range from the Mississippiam Sikanni field (Upper Debolt Formation) and Quirk

Creek (Turner Valley Formation), and the Devonian Slave Point Formation (Jedney field) in NE

British Columbia (Fig. 42). The above salinity range for Jedney, Sikanni and Quirk Creek as mentioned previously is associated with the Laramide Orogeny. Therefore lower salinity values are observed towards NE British Columbia.

This suggest the effect of compartmentalization of hydrothermal fluids in the basin within the same age group and between the Devonian and Mississippian as well (Figs. 39, 40, 41 and 42).

British Columbia

Alberta

Figure 39. Spatial variation of the oxygen isotopic values of saddle dolomite for the Mississippian and Devonian fields

British Columbia

Alberta

Figure 40. Spatial variation of the carbon isotopic values of saddle dolomite for the Mississippian and Devonian fields

British Columbia

Alberta

Figure 41. Spatial variation of the homogenization temperature of saddle dolomite for the Mississippian and Devonian fields

British Columbia

Alberta

Figure 42. Spatial variation of the salinity values of saddle dolomite for the Mississippian and Devonian fields

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100

Appendix I: Nomenclature

SD: Saddle Dolomite PD:Pervasive Dolomite MD:Matrix Dolomite CCD:Coarse Crystalline Dolomite FCMD: Fine Crystalline Matrix Dolomite MCMD: Medium Crystalline Matrix Dolomite PFC: Pore Filling Calcite FFC: Fracture Filling Calcite PFBC: Pore Filling Blocky Calcite PFEC: Pore Filling Equant Calcite PFCS: Pore Filling Calcite Spar LFCC: Late Fracture Filling Calcite EFCC: Early Fracture Filling Calcite

Th : Homogenization Temperature

Tm: Last Melting Temperature TOC: Total Organic Carbon

101

Appendix II: Geochemical Results

102

Table 2. Dolomite isotope results summary from previous and current data (data with * are from the current study)

Field Sample ID Lithology δ18O (VPDB) δ13C (VPDB) -8.6 2.78 Saddle dolomite -9.62 2.73 Saddle dolomite -9.47 2.08 Saddle dolomite -10.15 2.53 Saddle dolomite -8.47 3.43 Saddle dolomite -9.5 3 Saddle dolomite -8.83 2.36 Saddle dolomite -8.44 2.72 Saddle dolomite -8.6 2.83 Saddle dolomite -8.55 2.53 Saddle dolomite -9.34 2.51 Saddle dolomite -9.27 3.3 Saddle dolomite -8.3 1.13 Saddle dolomite -8.38 2.71 Saddle dolomite -9.85 1.38 Saddle dolomite -9.52 2.5 Saddle dolomite -8.72 3.75 Saddle dolomite -9.28 1.81 Saddle dolomite -9.71 2.24 Saddle dolomite -9.31 2.79 Saddle dolomite -8.14 2.91 Saddle dolomite 32-1-SD fracture filling saddle dolomite -9.81 1.8 32-1-SD fracture filling saddle dolomite -10.8 1.9 32-2-SD fracture filling saddle dolomite -8.71 2.44 Sikanni 32-2-SD fracture filling saddle dolomite -8.78 2.53 32-10-SD fracture filling saddle dolomite -9.85 1.67 32-10-SD fracture filling saddle dolomite -9.47 2.08

103

breccia related fracture filling 32-6-SD SD -9.42 2.56 breccia related fracture filling 32-6-SD SD -9.62 2.73 32-5-SD pore filling saddle dolomite -9.4 2.32 32-3-SD pore filling saddle dolomite -8.8 2.49 32-3-SD pore filling saddle dolomite -8.95 2.6 32-9-SD pore filling saddle dolomite -9.07 2.62 32-9-SD pore filling saddle dolomite -9.47 1.54 14-3-SD pore filling saddle dolomite -8.17 1.48 46-19-SD pore filling saddle dolomite -7.95 3 46-19-SD pore filling saddle dolomite -8.88 2.8 46-20-SD pore filling saddle dolomite -7.82 3.07 46-20-SD pore filling saddle dolomite -8.27 3.05 77-1-MD matrix dolomite -7.99 3.55 77-2-MD matrix dolomite -6.52 3.04 77-3-MD matrix dolomite -7.48 2.55 77-4-MD matrix dolomite -6.73 3.16 14-1-MD matrix dolomite -10.03 3.09 46-15-MD matrix dolomite -7.84 3.33 46-22-MD matrix dolomite -7.46 3.99 46-23-MD matrix dolomite -3.8 3.73 46-24-MD matrix dolomite -7.23 3.63 46-25-MD matrix dolomite -6.03 3.94

03-33-SD pore filling saddle dolomite -13.78 2.26 06-07-SD pore filling saddle dolomite -12.71 2 06-20-SD pore filling saddle dolomite -11.97 2.26 6-20-SD pore filling saddle dolomite -12.61 2.2 Hamburg 6-20-SD pore filling saddle dolomite -12.98 2.11 16-25-SD pore filling saddle dolomite -12.74 2.17 16-25-SD pore filling saddle dolomite -13.95 2.05

104

12-08-SD pore filling saddle dolomite -12.18 2.06 13-35-SD pervasive saddle dolomite -12.71 3.02 15-12-SD fracture filled saddle dolomite -12.86 2.26 15-12-SD fracture filled saddle dolomite -13.16 1.19 10-10-SD fracture filled saddle dolomite -12.57 2.18 10-10-SD fracture filled saddle dolomite -12.61 2.14 10-10 0204 fracture filled saddle dolomite -12.10 2.20 03-06-SD fracture filled saddle dolomite -13.93 1.35 03-06-MD matrix dolomite -11.62 1.41 03-33-MD matrix dolomite -10.77 3.17 03-33-MD matrix dolomite -10.14 2.18 10-10-MD matrix dolomite -10.24 0.97 10-19-MD matrix dolomite -9.43 2.39 12-26-MD matrix dolomite -10.56 0.67 13-35-MD matrix dolomite -9.34 0.2 13-35-MD matrix dolomite -10.09 2.6 15-12-MD matrix dolomite -11.6 0.87 03-06-PD Pervasive dolomite -10.3 3.08 03-33-PD Pervasive dolomite -10.4 3.5 10-19-PD Pervasive dolomite -11.74 2.01 10-19-PD Pervasive dolomite -10.22 2.32 12-26-PD Pervasive dolomite -11.03 2.04 13-35-PD Pervasive dolomite -10.83 2.79 13-35-PD Pervasive dolomite -9.5 2.02 pore filling saddle dolomite -12.99 0.93 pore filling saddle dolomite -13.97 -0.36 pore filling saddle dolomite -14.08 -0.23

Jedney pore filling saddle dolomite -13.31 0.81 pore filling saddle dolomite -13.17 0.81 pore filling saddle dolomite -14.62 -0.12 J10* fracture filling saddle dolomite -13.16 0.62

105

J4* pore filling saddle dolomite -13.68 0.67 J6* pore filling saddle dolomite -13.42 0.70 MD-1 matrix dolomite -13.13 0.91 MD-2 matrix dolomite -12.74 1.51 MD-3 matrix dolomite -13.04 1.14 MD-4 matrix dolomite -13.25 1.23 MD-5 matrix dolomite -13.08 0.86 MD-6 matrix dolomite -12.89 1.30 MD-7 matrix dolomite -13.14 0.98 MD-8 matrix dolomite -12.94 1.12 D1* fracture filling saddle dolomite -11.78 -2.08 D5* fracture filling saddle dolomite -6.26 1.75 D9* fracture filling saddle dolomite -6.55 2.49 D3* pore filling saddle dolomite -9.01 1.64 DU6-4-1 fracture filling saddle dolomite -5.58 3.16 Duvernay DU1-4-1 Pervasive dolomite -8.48 0.03 DU11-1-2 Pervasive dolomite -6.23 -0.02 D7-MD1* martix dolomite -6.24 1.96

D7-MD2* matrix dolomite -6.66 2.14

DU13-1-3 matrix dolomite -6.42 3.20 6-7-771 pervasive matrix dolomite -1.11 2.83 6-7-102 pervasive matrix dolomite -3.79 0.85 6-7-90 pervasive matrix dolomite -5.46 2.59 6-7-781 pervasive matrix dolomite -2.17 2.97 12-22-21 pervasive matrix dolomite -3.74 3.09 Quirk Creek 12-22-17 pervasive matrix dolomite -4.39 3.43 12-22-16 pervasive matrix dolomite -2.49 3.35 12-22-8 pervasive matrix dolomite -4.19 3.07 12-22-8 pervasive matrix dolomite -3.12 3.40 12-22-3 pervasive matrix dolomite -3.38 3.52

106

14-12-28 pervasive matrix dolomite -3.83 2.53 14-12-22 pervasive matrix dolomite -5.13 3.47 14-12-21 pervasive matrix dolomite -3.23 2.43 14-12-17 pervasive matrix dolomite -2.91 2.93 14-12-8 pervasive matrix dolomite -4.29 3.37 14-12-3 pervasive matrix dolomite -4.81 2.58 6-7-770 pervasive matrix dolomite -4.01 2.07 12-22-12 pervasive matrix dolomite -4.05 2.39 6-7-770 pervasive matrix dolomite -3.84 2.39 6-7-764 pervasive matrix dolomite -3.31 1.52

Q2-Sd* pore filling saddle dolomite -9.01 -1.99

107

Table 3. Calcite Isotope results summary from previous and current data (data with * are from the current study)

Field Sample lithology δ18O (VPDB) δ13C (VPDB) 14-12-18QC* Pore filling blocky Calcite -9.96 -7.24 91-100(QC)* Fracture filling calcite -9.82 -3.44 Q4* Pore filling blocky Calcite -13.71 -4.07 Pore filling Equant Calcite 6-7-101 spar cement -12.48 -5.82 Pore filling Equant Calcite 6-7-100 spar cement -12.04 -6.46 Pore filling Equant Calcite 14-12-9 spar cement -12.18 -9.05 Pore filling Equant Calcite 14-12-18 spar cement -11.24 -9.5 Pore filling Equant Calcite 14-12-4 spar cement -9.33 -9.67 Pore filling bladed prismatic Quirk Creek .12-22-30 Calcite -5.56 -0.31 Pore filling bladed prismatic .12-22-12 Calcite -6.2 -8.4 6-7-770 Pore filling blocky Calcite -7.19 -3.2 .6-7-97 Pore filling blocky Calcite -7.65 -2.07 Pore filling Coarse Mosaic .12-22-20 Calcite Spar -11.67 -2.82 Pore filling Coarse Mosaic 14-12-23 Calcite Spar -10.44 -9.44 Pore filling Coarse Mosaic 14-12-13 Calcite Spar -9.31 -9.29 Pore filling Coarse Mosaic 14-12-12 Calcite Spar -12.33 -12.69 Pore filling Coarse Mosaic 14-12-23 Calcite Spar -10.44 -9.44 Pore filling Equant Calcite 06-07 SP spar cement -6.92 1.76 Pore filling Equant Calcite 10-19 SP spar cement -7.13 2 Hamburg Pore filling Equant Calcite 12-26- SP spar cement -8.76 -0.7 Pore filling Equant Calcite 13-35SP spar cement -11.3 0.37

108

Pore filling Equant Calcite 13-35 SP spar cement -10.74 1.57 Pore filling Equant Calcite 13-35 SP spar cement -8.46 2.56 Pore filling Equant Calcite 15-12 SP spar cement -8.32 1.51 Pore filling Blocky Euhedral 6-07 LSB Calcite -11.88 1 Pore filling Blocky Euhedral 12-08 LSB Calcite -14.03 0.58 Pore filling Blocky Euhedral 13-35 LSB Calcite -12.11 1.02 Pore filling Blocky Euhedral 13-35 LSB Calcite -13.2 1.03 Pore filling Blocky Euhedral 13-35 LSB Calcite -14.8 1.53 Pore filling Blocky Euhedral 15-12 LSB Calcite -14.59 0.96 Pore filling Blocky Euhedral 15-12 LSB Calcite -11.67 1.36 Pore filling Blocky Euhedral 15-12 LSB Calcite -12.48 1.28 Pore filling Blocky Euhedral 16-25 LSB Calcite -12.04 1.08 Pore filling Blocky Euhedral 16-25 LSB Calcite -11.84 1.53 Pore filling Blocky Euhedral 16-25 LSB Calcite -13.03 1.25 fracrture filling calcite D1* cement -11.40 -1.89 fracture filling calcite D6* cement -7.42 -0.11 fracture filling calcite D9* cement -5.52 2.37 Duvernay pore filling blocky calcite D2* cement -9.93 -2.17 pore filling blocky calcite D5* cement -7.19 1.32 pore filling blocky calcite D8* cement -7.73 0.58

109

DU3-1-1 Pore filling blocky Calcite -5.58 0.70 DU4-28-4 Pore filling blocky Calcite -10.63 -1.03 46-22-LC late fracture filling calcite -11.99 0.58 14-2-LC late fracture filling calcite -8.5 2.04 14-4-LC late fracture filling calcite -10.01 1.05 14-5-LC late fracture filling calcite -12.6 1.23 Sikanni 14-9-LC late fracture filling calcite -9.19 1.79 46-28-EC early fracture filling calcite -7.18 2.72 14-7-EC early fracture filling calcite -7.41 1.86 14-8-EC early fracture filling calcite -7 2.63

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Table 4. Summary of fluid inclusion results from previous and current data for saddle dolomite (results from Hamburg, Sikanni and Jedney are from Clarke, 1998, White, 1995 and Al-Aasm, 1996; Duvernay and Quirk Creek results are from the current study)

Fluid Inclusion Data Salinity Field Samples Lithology Th( pressure corrected) (°C) wt.%Nacl 137.1 12.0 Saddle dolomite 173.7 Saddle dolomite 156.9 8.0 Saddle dolomite 115.3 8.0 Saddle dolomite 115.3 8.0 Saddle dolomite 107.4 Sikanni Saddle dolomite 32-8-SD1 fracture filling saddle dolomite 214.25 --- fracture filling saddle dolomite 114.39 10.5 32-8-SD2 fracture filling saddle dolomite 131.19 10.5 fracture filling saddle dolomite 87.69 6 46-2-SD1 fracture filling saddle dolomite 91.65 2 fracture filling saddle dolomite 137.13 7 06-20-01SD pore filling nonplanar saddle dolomite 125 22.2 06-20-02SD pore filling nonplanar saddle dolomite 136 24.5 06-20-03SD pore filling nonplanar saddle dolomite 142 24.1 06-20-04SD pore filling nonplanar saddle dolomite 146 22.3 06-20-05SD pore filling nonplanar saddle dolomite 151 24.7 06-20-06SD pore filling nonplanar saddle dolomite 161 22.9 Hamburg 13-35-01SD pervasive saddle dolomite 127 22.3 13-35-02SD pervasive saddle dolomite 134 23.2 13-35-03SD pervasive saddle dolomite 135 23.6 12-26-01SD pore filling nonplanar saddle dolomite 158 22.8 12-26-02SD pore filling nonplanar saddle dolomite 147 24 12-26-03SD pore filling nonplanar saddle dolomite 149 24.6 183.43 11.81 Jedney SD pore filling nonplanar saddle dolomite

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186.28 10.16 SD pore filling nonplanar saddle dolomite 173.8 11.58 SD pore filling nonplanar saddle dolomite 191.78 9.66 SD pore filling nonplanar saddle dolomite 179.99 11.24 SD pore filling nonplanar saddle dolomite 170.95 11.35 SD pore filling nonplanar saddle dolomite 162.5 10.77 SD pore filling nonplanar saddle dolomite 162.99 11.24 SD pore filling nonplanar saddle dolomite 189.72 10.16 SD pore filling nonplanar saddle dolomite 184.12 11.35 SD pore filling nonplanar saddle dolomite 185.59 9.28 SD pore filling nonplanar saddle dolomite 121.5 12.1 Q2-SD pore filling nonplanar saddle dolomite 200 12.1 Q2-SD pore filling nonplanar saddle dolomite 171 12.1 Q2-SD pore filling nonplanar saddle dolomite 110 ----- Quirk Q2-SD pore filling nonplanar saddle dolomite Creek 150 10.5 Q2-SD pore filling nonplanar saddle dolomite 130 10.9 Q2-SD pore filling nonplanar saddle dolomite 130 11.1 Q2-SD pore filling nonplanar saddle dolomite 132 13.2 Q2-SD pore filling nonplanar saddle dolomite fracture filling saddle dolomite 136.5 20.6 D5-SD Duvernay fracture filling saddle dolomite 141 23.2 D5-SD

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Table 5. Summary of fluid inclusion results from previous and current data for calcite (results from Hamburg and Sikanni are from Clarke, 1998 and White, 1995; Duvernay and Quirk Creek results are from the current study)

Fluid Inclusion Data Salinity Field Samples Lithology Th( pressure corrected) (°C) wt.%Nacl late fracture filling calcite 117.35 0 14-9-LC1 late fracture filling calcite 145.04 0 14-9-LC2 late fracture filling calcite 153.94 0 late fracture filling calcite 166.79 -- late fracture filling calcite 130.21 0 14-2-LC1 late fracture filling calcite 145.04 0

Sikanni late fracture filling calcite 147.01 0 late fracture filling calcite 145.04 - late fracture filling calcite 196.45 0 late fracture filling calcite ------0 14-2-LC2 late fracture filling calcite ------0 late fracture filling calcite ------0 14-2-LC3 late fracture filling calcite 132.18 0 12-26 Blocky Euhedral calcite cement 96 23.7 12-26 Blocky Euhedral calcite cement 102 23.4 12-26 Blocky Euhedral calcite cement 120 23.4 Hamburg 12-26 Blocky Euhedral calcite cement 127 24 13-35 Blocky Euhedral calcite cement 107 24.6 13-35 Blocky Euhedral calcite cement 114 23.6

Q4-Ca Pore filling blocky Calcite 138 22.5

Quirk Q4-Ca Pore filling blocky Calcite 132.5 10.5 Creek Q4-Ca Pore filling blocky Calcite 136.5 7

D1-Ca fracture filling calcite cement 113 20.6 Duvernay D1-Ca fracture filling calcite cement 102 19.8

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Vita Auctoris

Name: Carole Mrad

Place of Birth: Beirut, Lebanon

Year of Birth: 1989

Education: American University of Beirut. 2009-2012, B.Sc. (Geology)

University of Windsor.2014-2016, M.Sc. (Geology)

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