INFORMATION TO USERS
This manuscript has been reproduced trom the microfilm master. UMI films the text directly from the original or copy submitted. Thus, sorne thesis and dissertation copies are in typewriter face, while others may be tram any type of computer printer.
The quality of this reproduction is dependent upon the quallty of the copy submittecl. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. ln the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.
Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing trom left to right in equal sections with small overtaps.
ProOuest Information and Leaming 300 North Zeeb Road, Ann Arbor, MI 48106-1346 USA 800-521-0600
NOTE TO USERS
This reproduction is the best copy available.
•
McGILL UNIVERSITY
THE ORIGIN AND TIMING OF LATE-STAGE CARBONATE CEMENTS IN DEVONIAN CARBONATES OF THE DEEP ALBERTA BASIN: BASED ON FLUID INCLUSION A~1) ISOTOPIC EVIDENCE.
by
Séan G. W. Smith
A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfilment of the requirements for the degree of Master of Science
Depanment of Earth & Planetary Science
MONTRÉAL. QUÉBEC © Spring, 2001 • National Ubrary BibIiaIIWque nationale 1+1 ofCMada du canada Acquisitions and Acquilitions et Bibliographie services _Niees bibliographiques 315 W"tgIDn SIrwt ••rua V91e1ing1an QIa.- ON K1A 0N4 a.-ON K1A 0N4 c..dII c..da
The author bas granted a non L'auteur a accordé une licence non exclusive licence aIloWÎDg the exclusive pennettant à la Natiœal Library ofCaoada ta Bibliothèque Datiouale du Canada de reproduce, loan, distnbute or sen reproduite, prêter, distribuer ou copies ofthis tbesis in microfonn, vendre des copies de cette thèse sous paper or electrODÎc formats. la forme de microfiche/film, de reproduction S1U' papier ou sur format électronique.
The author retains ownershïp ofthe L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substaDtial extraets from it Ni la thèse Di des extraits substantiels may be printed or otherwise de ceUe-ci ne doivent être imprimés reproduced witbout the autbor's ou autrement reproduits sans son permission. autorisation.
0-612-70506-4 ABSTRACT
• Deep basin Leduc Qbed and Swan Hills Simonette calcite fluid inclusions yielded Th ranges of 127 to 172°C and 122 ta 15SoC; while saddle dolomites have Th from 136 to 148°C and 133 ta 162°C, respectively. Calcite data from the subsurface suggest a 2üoC/km geothermal gradient and saddle dolomite data a gradient around 23°C. Vug filling calcites from Spray Lakes, Parker's Ridge and Big Hill, yielded Th data (128.0 to 155.1°C) similar to vug-filling cements from Obed and Simonette. While inclusions are, on average, more saline at Simonette (calcites =22.7, saddle dolomites =20.9 - ail data in wt% NaCI eq.) and Qbed (19.7 and 20.8) than those in cements from outcrops, synthrusting fractures in Front and Main Range outcrops yielded a wider range for both Th and salinity. A late dolomite cement filling a synthrusting fracture at Spray Lakes has the highest average Th of aIl the samples studied (193.0°C, salinity = 18.6). Fluids in the fracture-filling saddle dolomites analysed have an average Th of 171.6°C and salinity of 17.1. Post-thrusting fractures yielded calcites with the lowest Th and salinity suggesting precipitation from cooler. largely meteoric waters. Homogenization temperature data for vug and fracture-filling from subsurface and outcrops suggest that late calcite and dolomite phases \Vere precipitated near maximum burial, in the Paleocene. Many of the Qbed and Simonette late-stage calcites and dolomites have very high 87Sr/86Sr signatures (up to 0.7370). Obed late calcites show a strong east to west increasing trend in Sr isotopes across the buildup - suggesting fault control of this margin. In Simonette. saddle dolomites show a positive correlation between S7Sr/86Sr and the proximity to faults. At Obed and Simonette, samples enriched in S7Sr generally have lighter 8180 signatures. Qbed late calcites exhibit a wide range of cS I3C values (i.e., 1 to 27). most probably due to T5R. At Simonette bath late calcites and saddle dolomites have heavy Ôl3C signatures relative ta Obed (-0.92 to 3.76) presumably because TSR reactions did not take place. Among Devonian outcrops calcite and dolomite cements filling tectonic fractures. vugs and molds contained the most elevated 87Sr/86Sr, with samples from a fracture at Cold Sulphur Spring yielding the highest ratio (calcite =0.71277, saddle dolomite = 0.71283). Late carbonate cements from outcrop do not reflect genesis from a strongly radiogenic fluid, unlike sorne deep subsurface samples. Thus the Southesk Cairn reef complex does not appear to have been a conduit for radiogenic Sr tluids. The late-stage vug and fracture-filling cements from outcrop generally have light Ô13C similar to Obed, suggesting that TSR also occurred in these rocks prior to uplift of the Front and Main ranges. • ii
RÉsUMÉ
Les résultats d'inclusions fluides sur la calcite des bassins profonds de Leduc • Obed et Swan Hills Simonette donnent des Th de 127 à 172°C et 122 à IS8°C; tandis que les dolomites baroques ont des Th de 136 à 148°C et 133 à 162°C. Les données sur la calcite de subsurface suggèrent un gradiant géothermique de 20°C/km et celles de la dolomite baroque un gradiant d'environ 23°e/km. Les calcites de remplissage de cavités de Spray Lakes, Parker's Ridge et Big Hill, ont des données Th (128.0 à ISS.I°C) similaires à celles des ciments de remplissage de cavités de Obed et Simonette. Les inclusions fluides sont, en moyenne, plus salines à Simonette (calcites =22.7, dolomites baroques =20.9 - données en poids% NaCI éq.) et Qbed (19.7 et 20.8) que celles des ciments des affleurements. Par contre, les fractures syn-chevauchement des affleurements des chaines fromales et primaires donnent un plus grand écart de résultats pour les Th et les salinités. Un ciment dolomitique tardif remplissant une fracture syn-chevauchement à Spray Lakes possède la plus haute moyenne de Th et salinité panni les échantillons étudiés (193.0°C, salinité = 18.6). Les fluides analysés dans les dolomites baroques de remplissage de fractures ont une moyenne de Th de 171.6°C et de salinité de 17.1. Les calcites dans les fractures post-chevauchement donnent des plus basses Til et des salinités suggérant une précipitation à partir d'eaux plus froides et essentiellement météoritiques. Les données de Th pour les phases de calcite et de dolomite tardi'le remplissant cavités et fractures en subsurface et en aftleurement suggèrent que celles-ci ont precipité dans des conditions d'enfouissement presque maximum au Paléocène. Plusieurs des calcites et des dolomites tardives de Obed et Simonelte ont un ratio S7Sr/S6S r très élevé (jusqu'à 0.7370). Les calcites tardives de Obed montrent une tendance très marquée, de l'est vers l'ouest, d'augmentention des valeurs d'isotopes de Sr au travers l'accumulation, ce qui suggère une marge contrôllée par les failles. A Simonette, les dolomites baroques montrent une correlation positive entre le 81Sr/86Sr et la proximité des failles. A Obed et Simonette, les échantillons enrichis en 87Sr ont généralement une signature en 5180 plus légère. Les calcites tardives de Obed montrent un grand écart de valeurs de ô13e (i.e., 1 à -27), probablement causé par les RST. A Simonette, les calcites tardives et les dolomites baroques sont enrichies en isotopes lourds de 13e en comparaison à Obed (-0.92 à 3.76), supposément parce que les réactions RST ne se sont pas produites. Parmi les affleurement Dévoniens, les ciments calciques et dolomitiques remplissant les fractures tectoniques, les cavités et les moulages contiennent les valeurs les plus élevées de 87Sr/86Sr. Un échantillon d'une fracture à Cold Sulphur Spring montre le ratio le plus élevé (calcite =0.71277, dolomite baroque =0.71283). Les ciments carbonatés tardifs des affleurements ne reflètent pas une genèse à partir d'un fluide très radiogénique, au contraire de certains échantillons de subsurface profonde. Ainsi le complexe récifal de Southesk Cairn ne semble pas avoir été un conduit pour les fluides radiogéniques de Sr. Les ciments tardifs de remplissage de cavités et de fractures en affleurement sont généralement appauvris en 13e comme celles de Obed, suggérant que les TSR se sont aussi produites dans les réservoirs avant le soulèvement des chaines • frontales et primaires. iii
TABLE OF CONTENTS Page ABSTRACT i • RÉSUMÉ 11 Table of Contents iii List of Figures v List of Tables vii List of Plates viii List of Appendices viii
ACKNOWLEDGEMENTS
CHAPTER 1: General Introduction
1.1: Rationale and Objectives 4 1.2: Study Area 5 1.3: Previous \Vork II 1.3.1: Late-stage Dolomites 13 1.3.2: Late-stage Calcites 16 1.3.3: General Diagenetic Trends 18 1.4: Methodology 19 1.4.1: Samples 19 1.4.2: Petrography 20 1.4.3: Auid Inclusion Analyses 21 1.4.4: Isotope Analyses 21 1.5: Thesis Organisation 22 1.6: Acknowledgements 22
CHAPTER 2: Fluid Inclusions in Late-Stage CARBONATE Cements 23 Devonian Strata. Deeo Alberta Basin
2.1: Qbed 24 2.1.1: Stratigraphy 24 2.1.2: Paragenesis 28 2.1.3: Petrography 29 2.1.4: Fluid Inclusion Description 30 2.1.5: Homogenisation Temperature Data (Th) 30 2.1.6: Freezing Point Depression Data (TnJ 31 2.1.7: Isotopie Evidence 35 2.2: Simonette Buildup 40 2.2.1: Paragenesis 41 2.2.2: Petrography 41 2.2.3: Homogenisation Temperature Data (Th) 44 2.2.4: Freezing Point Depression Data (Tm) 45 2.2.5: Isotopie Evidence 49 • 2.3: Burial History of Deep Subsurface 52 iv
Page CHAPTER 3: Devonian Outcrops of the Rocky Mountains; Fluid • Inclusion and Isotope Data 3.1: Stratigraphy 60 3.2: Paragenesis 62 3.3: Fluid Inclusion Evidence from the Front Ranges 64 3.3.1: Disaster Point 64 3.3.2: CoId Sulphur Spring 68 3.3.3: Toma Creek 68 3.3.4: Spray Lakes 69 3.3.5: Marmot Cirque 69 3.4: Fluid Inclusion Evidence from the Main Ranges 72 3.4.1: Parker Ridge 72 3.4.2: Big Hill 73 3.4.3: Cirrus Mountain 73 3.4.4: Rice Brook 77 3.5: Geochemical Evidence 77 3.6: Burial History of the Front and Main Ranges 78
CHAPTER 4: Summarv and Conclusions 82 4.1: Fluid Incusion Data 82 4.1.1: Qbed 83 4.1.2: Simonette 83 4.1.3: Front and ~fain Ranges 84 4.1: Geochemical Evidence 84 4.2.1: Obed 85 4.2.2: Simonette 86 4.1.3: Front and Main Ranges 87 4.3: Relationship to Burial History and Tectonism 87 4.4: Timing of Cement Stages 89 4.5: Potential Fluid Sources and Constraints on Fluid Aow 90 4.6: Conclusions 92
REFERENCES CITEO 95
• v
LIST OF FIGURES Page • CHAPTER 1 Figure 1-1 - Devonian buildups of the Alberta Basin 2 Figure 1-2 - Cross-section illustraling Middle and Upper Devonian reefs 3 Figure 1-3 - Devonian outcrop samples - Fronl Ranges of the Rocky Mountains 6 Figure 1-4 - Major Woodbend reef complexes and basins in the Obed area 7 Figure 1-5 - The Obed platform - sample locations 8 Figure 1-6 - The Simonette buildup - sample locations 9 Figure 1-7 - Classification of diagenetic environments 12
CHAPTER 2
Obed Figure 2-1 - General stratigraphy and depth of fonnalions, Obed area 25 Figure 2-2 - Schematic structural cross-section across Obed area 26 Figure 2-3 - Paragenetic sequence for Obed 27 Figure 2-4 - Histograms of tluid inclusion data for carbonate cements. Obed 32 Figure 2-5 - Location. depth and average Th for Obed sampies 33 Figure 2-6 - Average Th versus present and maximum bunal depth 33 Figure 2-7 - Location. depth and average salinity for Obed samples 34 Figure 2-8 - Th versus Tm for Obed calcite and dolomite cements 34 Figure 2-9 - Average salinity versus present burlal depth. Obed calcites 36 Figure 2-10 - Distribution of 87Sr/~6Sr values for calcite cements. Obed 36 Fibure 2-11a - 8iSr/86Sr versus range for Obed calcites and dolomites 37 Figure 2-11b - ..87Sr/~6Sr versus to;nship for Qbed calcites and dolomites 37 Figure 2-12 - 8/Sri~6Sr versus present burial depth, Obed calcites and dolomites 38 Figure 2-13 - Ô 13C versus present burial depth, Obed calcites and dolomites 38 Figure 2-14a - 87Sr/86Sr versus S 180 for Obed calcite and dolomite cements 39 18 Figure 2-14b - Ô l3C versus S 0 for Obed calcite and dolomite cements 39
Simonette Figure 2-15 - Stratigraphy - Beaverhill Lake Group, Swan Hills Simonette area 42 Figure 2-16 - Stratigraphy of Simonette area 42 Figure 2-17 - Paragenetic sequence for Swan Hills Simonelte buildup 43 Figure 2-18 - Auid inclusion data histograms, Simonette calcites and dolomites 46 Figure 2-19 - Location. depth and average Th, Simonette calcites and dolomites 47 Figure 2-20 - Average Th versus present and maximum burial depth, Simonette 47 calcites and dolomites Figure 2-21 - Tm versus present burial depth, Simonette calcites and dolomites 48 • vi
LIST OF FIGURES (cont'd) Page • CHAPTER 2 (cont'd) Simonette (cont'd) Figure 2-22 - Th versus Tm for Simonette calcite and dolomite cements 48 Figure 2-23 - 87Sr/86Sr versus present burlal depth, calcite and dolomite cements 50 Figure 2-24 - 87Sr/86Sr versus township and range, calcite and dolomite cements 50 Fi2ure 2-25a - 87Srl~6Sr versus Ô 180 for Simonette calcite and dolomite cements 51 Figure 2-25b - 5 13C versus 5 180 for Simonette calcite and dolomite cements 51 Figure 2-26 - Maps estimating the amount of erosion from the Alberta basin 53 Figure 2-27a - Burial history, Leduc Obed reservoir 55 Figure 2-27b - Burial history, Swan Hills Simonette reservoir 55
CHAPTER 3
Figure 3-1: Upper Devonian stratigraphy, west-central Alberta basin and outcrops 61 Figure 3-2: General paragenetic sequence, Front and Main Range outcrops 63 Figure 3-3a: Histogram of Th data for calcite SM-53 from Disaster Point 65 Figure 3-3b: Histogram of salinity data from late-stage calcite SM-53 65 Figure 3-3c: Histogram of Th data for calcite SM-50 from Disaster Point 65 Figure 3-3d: Histogram of salinity data from late-stage calcite SM-50 65 Figure 3-4: Th versus Tm for late-stage carbonate cements from Front Ranges. 66 Figure 3-5a: Histogram of Th data for calcite SM-54C from Cold Sulphur Springs 67 Figure 3-5b: Histogram of salinity data for late-stage calcite SM-54C 67 Figure 3-5c: Histogram of Th data for late-stage dolomite SM-54D 67 Figure 3-5d: Histogram of salinity measurements for SM-54D 67 Figure 3-6a: Histogram of Th data for calcite l\1M5 from Toma Creek 70 Fi !!ure 3-6b: Histogram of salinitv measurements for MM5. 70 ~ . Figure 3-7a: Histogram- of Th data for calcite SM-77 from Spray Lake 71 Figure 3-7b: Histogram of salinity for late-stage calcite SM-?7 71 Figure 3-7c: Histogram of Th data for dolomite SM-78 from Spray Lake 71 Figure 3-7d: Histogram of salinity for late-stage dolomite SM-78 71 Figure 3-8a: Histogram of Th data for calcite SM-59 from Parker's Ridge 74 Figure 3-8b: Histogram of salinity for calcite SM-59 from Parker's Ridge 74 Figure 3-8c: Histogram of Th data for calcite SM-60 from Big Hill 74 Figure 3-8d: Histogram of salinity for calcite SM-60 from Big Hill 74 Figure 3-9a: Histogram ofTh data for saddle dolomite SM-69, Cirrus Mountain 75 Figure 3-9b: Histogram of salinity for saddle dolomite SM-69, Cirrus Mountain 75 Figure 3-9c: Histogram ofTh data for calcite SM-70, Cirrus Mountain 75 Figure 3-9d: Histogram of salinity for calcite SM-70, Cirrus Mountain 75 Figure 3-10: Th versus Tm for Main Range late-stage carbonate cements 76 Figure 3-1Ia: 81Sr/86Sr versus Ô 180. Front and Main Range calcites and dolomites 76 18 Figure 3-1Ib: Ô 13C versus Ô 0, Front and Main Range calcites and dolomites 76 • Figure 3-12: Bunal history, Devonian buildups, Front Ranges 79 vii
LIST OF TABLES • Chapter 1 Page Table 1-1: Types of replacement dolomite and dolomite cements 13 Table 1-1: Fluid inclusion analyses from the literature, Devonian subsurfaee, 14 Alberta Basin Table 1-3: Geochemistry of late-stage dolomite cements, Devonian subsurfaee, 15 Alberta Basin Table 1-4: Types of calcite cements in the deep subsurface of the Alberta Basin 16 Table 1-5: Published isotopie data, late-stage calcite cements, Deep Alberta Basin 17
Chapter 1 Table 1-1: Stratigraphie table, Obed area 28
Chapter 3 Table 3-1: Summary of tluid inclusion and isotopie data for Devonian outcrops 63
Chapter 4 Table 4-1: Summary of tluid inclusion data. late-stage carbonate cements 82 Table 4-2: Summary of isotopie data. late-stage carbonate cements 85
Appendix A Table A-l: Summary of Fluid Inclusion Data for Obed Samples 107 Table :\-2: Summary of Fluid Inclusion Data for Simonette Samples 110 Table A-3: Summary of Fluid Inclusion Data for Outcrop Samples 112
Appendix B Table B-l: Summary of Isotopie Data for Devonian Outerop Samples 115
Appendix C Table C-l: Criteria used to distinguish primary, seeondary, and pseudosecondary 116 tluid inclusions
• viii
LIST OF PLATES Page Obed • Plate l-A: Late-stage calcite from Obed buildup. 57 Plate I-B: Vug-filling late-diagenetic cements from Obed buildup. 57 Plate l-C: Obed late-stage calcite cements fiHing a vug associated with 57 stylolite. Plate 2-A: Twinning in Obed late-stage calcite cements. 58 Plate 2-B: Corroded saddle dolomite crystals Iining walls of vugs. 58 Plate 2-C: Primary fluid inclusions in late-stage calcite cements. 58
Simonette Plate 3-A: Coarse-grained. late calcite cement filling moldic porosity. 59 Plate 3-8: Late-stage calcite filling vuggy porosity near stylolite. 59 Plate 3-C: Saddle dolomite filling a vug. 59
Outcrop Samples Plate 4-A: Late-stage synthrusting fracture-filling calcite from outcrop at 81 Disaster Point Plate 4-8: Late-stage synthrusting fracture-filling calcite and saddle 81 dolomite phases from outcrop at Cold Sulphur Spring (normal light) Plate 4-C: Late-stage synthrusting fracture-filling calcite and saddle 81 dolomite phases at Cold Sulphur Spring (polarized light)
LIST OF APPENDICES
A: Auid Inclusion Data 107 8: Isotope Data 115 C: Recognition of Primary Fluid Inclusions and Pressure Correction 116 of Th data
• CHAPTERI • GENERAL INTRODUCTION In Alberta the Givetian to Uppermost Frasnian sequence represents a major
transgression that is divisible into smaller transgressive cycles, each consisting of a basal
carbonate platform on which isolated reefs developed. ending with basin filling. These
strata contain economically important reservoirs for hydrocarbons. Devonian platform
and buildups of the Alberta Basin (Figs. 1-1 and 1-2) have acted as permeable conduits
for the migration of petroleum and presumably for diagenetic tluids as weil (Machel and
Mountjoy. 1987~ Amthor et al.. 1993).
Carbonate cementation. often associated with chemical compaction (pressure
solution). is the most important process affecting porosity and penneability in these
reservoirs and conduits (Mountjoy. 1994; Mountjoy and Marquez, 1997). Limestone and
dolostone reservoirs have undergone bunal diagenesis throughout the basin (i.e.,
cementation, dissolution and recrystallization), although the deeper part of the basin has
been subjected to higher temperatures and pressures than the shallower eastem part. Yet,
the origin of the diagenetic tluids that preeipitated the late-stage carbonate cements found
in these Devonian reservoirs, and their timing, remains uncertain.
The overarching goal of this research is to provide tluid inclusion as weil as C, 0
and Sr isotopie data for the different late diagenetic phases within Devonian strata of the
deep Alberta basin and for the adjacent Front and Main Ranges of the Rocky Mountains
to the southwest. These analyses help to constrain the origin and timing of late-stage
cements in several deeply buried (i.e., -4 km) Devonian buildups within the west central • Alberta Basin, and in adjacent Rocky Mountains outcrops. Outcrop data presented in this Chapt~, 1: GENERAL INTRODUCTION •
Figure 1·1: Western Canada Sedimentary Basin showing the distribution of Devonian dolomite and limestone Leduc and Swan Hills reservoirs in the subsurface and outcrops (modifted from Mountjoy and Marquez~ (996).
• 2 •
UMESTONE DOLOMTE BEAVER HILL PLATFORM EDGE - ...... - SNAA HILLS PLATFORM EDGE .,...... ,... lIMIT OF REEF MASSES THRUST FAULT UMIT OF THRUST FOLO BEll
114" • 112" Chqe'~' 1: GENER-\'J n-.TRODtlCTION •
Figure 1·2: Schematic northwest-southeast cross-section of the Middle and Upper Devonian from the Northwest Territories to southern Albena and adjacent Saskatchewan, illustrating five levels of reef development, Keg River (Rainbow - Zama), Slave Point, Swan Hills, Leduc and Nisku (after Mountjoy and Amthor. 1994).
• 3 • •
Figure 1-2:
NDRTHWEST TERRITORIES NE BRmSH COLUMBIA WESTERN ALBERTA CENTRAl. ALBERTA 1 SASK. NW SE ? l.. l.. 1 1 "1 L
> " ,- } " '" ) 'SHELF ) CARBONATES )" '" ) , ~ . ~ .>. ," " 1 l" , 1 1 ._ J •• :. 1
1 •• :. FfMSNIAN.FAMEr-JNJAN STAGE BOUNDAI?V ,-:,/'....--.:.••••• _. - , ... __ ._--_ ....•.•...•...... •....•...... •• SHf.l.f MNK;IN BUI: RIDGE REEr COMPl [)ŒS 'NES, PEtJBJNA t\ NISKU - 1 NlSkU L/ •• -- FRA5NIAN SHAlE BASIN REsmlCTED -ARBONATES and FRASNIAN EVAPORITES ? ~ ?
a .... , "\', • ,,''',\ ...... '\<.,\:,>~~. "", '.;~., ' ...... _-~--~ + ~DOlE~,... "'~" PEACERMR '.':';,:,~ ~'<' MIDDLE + + + "'" .'.' :: '. '.'.. ; l.mJMASS t ". . ,,~<:: ..~..:\ ",' DEVONIAN . ,""',,,, \, ' + + + EVAPORITES C1mptt'r J: GENERAL INTRODUcnON
thesis from seven locations in the Front and Main Ranges, significantly increase the • geographical scope and quantity of published fluid inclusion evidence for late-stage calcite. dolomite. and saddle dolomite cements in exposed Devonian buildups of the
Alberta Basin.
Rationale and Objectives
This research provides new data that is critical for detennining the temperatures
and relative time at which the various cements precipitated. In addition. the isotopes
constrain the nature of the tluids responsible for these cements and limits the likely tluids
involved. This places important constraints on their possible origins. Also. this
information is very important for understanding how and when these cements affected the
porosity and perrneability of these and adjacent reservoirs.
Auid inclusion analyses detennine the approximate temperatures of formation of
late-stage calcite and dolomite cements. Homogenization temperature (Th) data obtained
from primary f1uid inclusions in cements help to constrain the timing of cementation
episodes and the buria! depth of the host formations at the lime of cement precipitation by
relating temperatures to inferred geothermal gradients and buria! history.
Freezing point depression (Tm), as weil as C, 0 and Sr isotope data provide sorne
aspects of the chemistry ofthe diagenetic fluids that precipitated these late-stage cements.
Tm data provide a measure of the salinity of the fonnation fluid, and along with Ôl80 and
S13C. can be used to constrain the source of this fluid (i.e., meteoric, marine, evaporative
13 brine. etc.). Ô C measurements can provide information on the timing of cementation
relative to organic maturation (i.e., methane oxidation, fennentation, biodegradation, and • thermal decarboxylation). 4 Chapra J: GENERAL INTRODUCTION
87Sr/86Sr data provide additional evidence about the origin of the fonnation fluid • (i.e.• continental, marine, burial or crustal), and if that source is marine 87Sr/86Sr can he used to constrain the timing of cementation. Sr isotope analyses were carried out on
outcrop samples to test for signs of the radiogenic fluid that left its 87Srl~6Sr signature on
the late-stage carbonate cements at Obed, Simonette, Kaybob and Kaybob South (Patey.
1995; Duggan et al.. 2001, in press; and Green. 1999). Data (n=15) presented in this
work from 9 Devonian outcrops in the Front and Main Ranges have imPOnant
implications for understanding basin·wide diagenesis and tluid tlow (Chapter 4, section
~.6).
Study Area
Middle and Upper Devonian carbonates oceur extensively in the subsurface of the
Alberta Basin (Figs. 1-1 and 1-2) and also are exPOsed in the fold and thrust bell of the
Rocky Mountains to the southwest (Figs. 1-1 and 1-3). The deep subsurface Obed and
Swan Hills Simonette buildups occur (i.e.• present burial depth - 4 km) immediately
northeast of the thrust-fold belt (Figs. 1-1 and 1-4).
The largely dolomitized Qbed reef complex is located on the southeastem side of
the \Vild River sub-basin (Switzer et al.. 1994). approximately 50 km northeast of the
defonned belt (Figs. 1-4 and 1-5). In the Obed buildup. Lower Winterbum reefal facies
overlie a Leduc reef (Fig. 2-2, Patey. 1995). It is unclear whether the Lower Winterbum
reef is Lower Blue Ridge or Upper Nisku equivalent. The carbonates of the Obed sour
gas field (i.e., 20 - 30% H2S) have a complex diagenetic history (Chapter 2, section 2.1,
Fig. 2.3). The present subsurface depth of the Obed reefal facies is greater than 3900 m. • It is estimated that Devonian reservoir rocks, at both Obed and Simonelte, were buried 5 C/Ulpter J: GENERAL INTRODUcnON •
Figure 1-3: Devonian outcrop sample locations in the Main and Front Ranges of the Rocky Mountains (unrestored).
• 6 • •
Figure 1·3: Devonian Outcrop Sample Locations, Front and Main Ranges of the Rocky Mountains
U.W u.w tHW lEGEND .-.- .-
~ Thrul' taul' ".", River n IJN c::::::::.\ Devonl.n Outcropl ALBERTA ln Main Rangel
• Sampllng Srte
FRONT RANGES OP - Disaster Point CSS· CoId Sulphur Spring .+o~.'\"sask..\.~~e"'a?Riv~ TC - Toma Crook .. ••••••••• •••• ... . SL· Spray Lakos MC - MarmotCirquo
MAIN RANGES PR - Pa~or's Ridgo BH - Big Hill CM • Cirrus Mountaln RB - Rico Brook
SCAlE ~a 20 Yu ~o mil•• fL\~~~. , d lU id Su=;( B.C. 6o:'~"" ••••••Calgar km 0 .... -·'t •• ..- ~ ..;' , , It . It N Charter /- GEr-.'ERAL INTRODUrnON •
Figure 1·4: Major Woodbend reef complexes and basins in subsurface study area (modified from Mossop and Shetsen. (994).
• 7 • Figure 1-4
,.:;.:.--=- -+_-~_,5n
LOWERLEDUC OR COOKING LAKE EQUIVALENT PLATFORM
J--+------j54-"
WEST SHALE BASIN
~ \~---,53-"
MAXIMUM THICKNESS LEDUC fORMATION
APPROXIMATE THICKNESS OF SCALE: MAXIMUM REEF BUILDUP o 50 100 km .>zeom lit 1 o 50 mi • Z3Q·260m o Lo..' Leduc • Cluzptt'r 1: GENERAL INTRODUCTION •
Figure 1-5: Sample locations. Obed LeduclNisku buildup (map modified from Patey. 1995).
• 8 • •
R24W5M R23 R21 Figure 1·5 31 36 i ; : t • ,PJn~acl~. ,.,
;R~ef ! ' T55 ~ . i. ,' 1 . ; ~ . . i : 1 l'''~lfi. ;" . lm ! j ,8 1...... '" ~ 6 f _., _::- "!' L._ ~; __,.; _... il .~"H '.II'l~y';:U H.. J-''. ~.W.llrr~"(·. ... Il.·.. -. (. S l'l"~~ ijlll IMWl ~... \...... ' l'tlI''',. ...'' -;.. 1ili!N.,,'! IUIU'.MI :s .... "\., '- 1,' ";': '; \1...... 'fln... ; ,Wj'i:E~ uu."' ...... N l.w " , ~ T54 ~.. ~,,- , .•'- \ f ...~ ~.:.,- > .~. ,:...~ 1 'I 1.. ( ~ \ --::. "} .. ~ .~/ . i 'i~LI_:_- '" .. ! J s..:.,. \ --t--,~-.-, " \ ..13 \/--.. ! .~. .' ,. 1 '~~RIMlIr,rIolEAOOWBH()()I( . : ~ ~ ~ j ~ ," • .;.. "H' lll(llO f . .. ~ !- ~ !H" : ~~~!.~'. , \ ,,-__ " ~, / 1 • .:. "1 L " ,;.j .'1C.""/ ,-...J:. .,...,."/) u,~.,~,:",. ~ ... ,,( i~llIU: c.:. T53 JA'ltR 1 ~'" /.. .' '1'; _ ...., l "\~,,~~.,,'\ "'ii:J _~~,.-:r ! 1>2'. _l 11.1"'/ ". ~:7\o1;;J!
\--- 1 (/ •••••• flollltt Figure 1-6: Swan Hills Simonette field (Township 64, Ranges 26 and 27 West of the 5th Mendian) (modified from Duggan, 1997). The reef margin and faults were interpreted from a 3-D sei smic survey (Ollenberger and Conis, (996). The regional dip is 15.5 rn/km. • 9 • • Range 1 (6th) Range 27 (5th) Range 26 (West of the 5th Meridian) Figure 1-6 li'> '0 a. • 'i: 1/) ~ {? ... •.... i'H~ :: (1-"1"" Di] J::1·"""''''''''''''''""'",L'I'\""~"""'.jl." _.- 1 1._~.----- '-t,' ''''18.::'::1 ~ __ ~ .: &.. ~...... -- f{lU ..'t~ -,---- N .~. o (Karr field) • • ;li a. 'i: 1/) ~ {1 lEGENO: • • Vertical Wells o Deviated Wells c:::J limit of Reservoir • c • • Ill· III 11.· liT 110' rl '0 a. '.E. &Il s;;;;;;; 1 C ~ o 5km 10 {d o After Duggan (1997) ClIapur J: GENERAL INTRODUcnON much more deeply during maximum burial. before a significant portion of overburden • was removed during Tertiary erosion (see Chapter 2, section 2.3). The Simonette buildup lies approximately LLO km northwest of Obed. and is situated about 75 km northeast of the thrust-fold belt (Figs. 1-4 and 1-6). The Swan Hills Simonette oil field of the west-central Alberta Basin is a partially-dolomitized Devonian buildup of the Swan Hills Fonnation (Givetian-Frasnian) (Duggan, 1997; Duggan et al, 200 1). \Vhile other dolomitized Devonian fields at similar depths (i.e.• >3000 m; e.g.• Kaybob South. Obed. Strachan. and Rosevear) contain sour gas. Simonette contains an estimated 40 million barrels of light. sweet crude (40 - 46° API. 0.3 to 1.1 % H25). Present burial depths for the Simonette oil field are only slightly shallower (3750 104000 m) than those of the Obed gas tield. Samples were also studied from vugs and fractures in several Devonian outcrops in the Front and Main Ranges (Fig. 1-3). Front Range samples studied are from Jasper National Park at CoId Sulphur Spring. Disaster Point. and Mannot Cirque. as weil as from the McConnell thrust sheet at Toma Creek just east of the Jasper Park boundary. Data are also presented from the Rundle thrust sheet in the Front Ranges along the Spray Lakes Road near Canmore. Main Ranges outcrop samples studied are from the footwall of the Simpson Pass thrust at Parker's Ridge and Big Hill. as weil as from Cirrus Mountain in northem Banff National Park. and west of Banff Park in British Columbia at Rice Brook. The Front and Main Ranges of the Rocky Mountains in Banff and Jasper Parks in southwestem Alberta contain numerous excellent exposures of Devonian strata. • Andrews (1989) and more recently Machel (1996) suggest that prior to defonnation and 10 ClraPfa 1: GENERAlll'o'TRODUCTlON uplift these strata were situated downdip of, and were presumably in hydraulic • communication with, the deep basin reservoirs such as Qbed and Simonette, and thus shared a similar burial and f1uid f10w history (Fig. 1-1). The strata of the Front Ranges were buried even more deeply than the Obed and Simonette fields (for burial history of Front and Main Ranges see Chapter 3, section 3.6). Previous Work As a basis for any research on diagenesis, it is imponant to first list the basic criteria used to distinguish diagenetie environments. Bustin et al. (1985) used the degree of organic maturation, as indicated by the vitrinite reflectance (Ra). to differentiate between eogenic (shallowest, Ro (deepest. Ro>2.0) settings. Galloway and Hodbay (1983) also incorporated hydrogeochemical and hydrologie criteria to differentiate between meteoric (burial depth <600 m). compactional (600 to 3600 m), and thermobaric (>3600 m) diagenetic environments. Acknowledging the myriad of variables and ex.ceptions that cao render these groupings invalid. or difficult to apply. Machel (1999) suggested a more complete and flexible system based on mineralogy, petroleum, hydrogeochemistry, and hydrogeology that is used here (Fig. 1-7). In this classification. shaJlow buriai gives way to intermediate buriai at the maximum penetration depth of dissoived ox.ygen (i.e.• 600 to 1000 m). and the deep burial environment begjns at the depth of the top ofthe oil window (i.e.• 2000 to 3000 m). The large range given for the intermediate/deep boundary is testament to the fact that the depth to the top of the oil window varies widely depending • on kerogen type and geothermal history. The deep buriaI environment gjves way to the 11 ClfLJDUr 1: GENERAL INTRODUCTION • Figure 1·7: Classification of Diagenetic Senings (from Machel. 1999). • 12 • • Figure 1·7: DIAGENETIC SETTINGS BASED ON MINERALOGY, GEOCHEMISTRY, PETROLEUM, AND HYDROGEOLOGY J~l~;~E-- ~ -< _; V / /7Tlm-~----"\"::=7./ Y . ~~d/. J / SHALLOW .~ze YSI::~ ._--600----100G-m- Reduced mineralogy chemical compaction INTERMEDIATE intermediate burlal cements BURIAL source rocks mature 2000---aoGO-m- Reduced mineralogy chemical compaction DEEP deep burial cements BURIAL source rocks mature or overmature fronl Machel, 1999 Charru 1: GENERAL INTRODUcnON metamorphic realm at around 200°C. and thus al a deplh lhat is dependenl on geothennal • gradient (i.e.• -6 km and 1.50 kbars at 30°CIkm~ and -9 km and 225 kbars at 20°C/km). This study focuses on lale-stage carbonate cements (calcites. as weil as planar and saddle dolomites) that fonned dunng deep bunal in the Devonian buildups of the western part of the Alberta Basin. A review of previous studies carried out on these late cements is followed by a summary of the general diagenetic trends that have thus far emerged for the subsurface. LaIe-stage Dolomites Late-stage dolomites occur as coarsely crystallinc cements in pores. vugs and TABLE 1·1a: Typq of replacement dotomlt. and dolomite cement.. deep aub.,rface of the Alberta BatJn Dcl'omlt8 TVDe 1 FlIlfic 1 On_ E..,.,~IC.___• "-.ç_~DY.• j:__ t Mealum-crystalhne platlal·s lTlO5aIC ~~-~...:. e_~,_ ~rystalhne l'cr.... _ ~ al a..etWll'. 2 gorgua ~al __~av---o:ryalaa ...... -.... piatlal·S(el mo&aIC ''''~DO'O&lIY L...... --c:..- .. ~ 10 "" Occurw"_II:I~<:ty1I___ J Coo1tscM;~ Ç)WW. ~~.- ee.r."'_.~c:Ote__-. C_ ...... 5(9) O'Y.__ZOIWI_ .....-.lIl.... ~~ 1rXIIIw. _.,.,.,...... "*"",,__-- 4. CaaI'54f-C)'St.i/1r16 CIy-'""....,------,... ~~Q/---- ~·a .-.r"-'-~-"- _,.".,...,... ~"_r,..z. e-~ __ ",.,.,.,.,~__ - s CÀdrse to WIry coarse 1.AI~e.t'e1l r.or'~<' .-.g~!Nt ~. DItlCIIy.".,... cryscaIrW ted ...... --. u-__~ ~""'''''''''~I ·w.-.::r.... ('!l9ll] dIlI...... _rtoo:llll'Uaal .-.-:wnt. T.... ' ... ~.. _-tn;mY~_1I"4 ..."."..,,,_f_~_tra:f~__dull::l_n--=..ca TABLE '-'b: Types of replKement dolomlte.,d dolomite «*Mnt.. Alberta Front R.-.ae. Dolomite Type 1 FIIlnc 1 OrtClln 1 Diffuse mlC1tlClY5la1l1re o.nu-. ~ _ etYW'- E-'Y~~ahCIn')fnl... ~ &1..ttlI.Inr'aa...". _ .. _ , MœaIc ca.. ra B.I>II~(~1 ~'.""~_""""l"'" ~._~_._~- ... ~utlIlC_~""" I~grc-_l""''''''-'~ 3. PreS$l.'Tllsou:a::n ~t6C F....."*U~__._~ "---"_._or~ ",~-~--- ~ 4. WMe~ ~-....,...-----.. s.-..... f.,J ~~_..-..- S. '!WoQue" e--._~--.-a.a.-- "--..--.01,...... -.... __.~.a1/w:t1 An.'-. _ fobnlay (llleDl • r~.1 ... _'.. r_f.l._b__laaaol..-. 13 Clumtt'r J: GENERAL INTRODlJcrtON fractures. fonning up to 5-10% of completely dolomitized rocks (Mountjoy and Amthor, • 1994, Mountjoy et al., 1999). They also occur in similar abundance and context in sorne limestones (Mattes and Mountjoy, 1980; Mountjoy and Halim-Dihardja, 1991). These late-diagenctic dolomites are more common in the deep basin than in shallower areas, where maximum burlal was less than 3 km (e.g., the Leduc and Grosmont formations along Rimbey-Meadowbrook reef trend) (Amthor et al., 1993; Mountjoy and Amthor. (994). \Vendte et al. (1998) integrated the use of tlorescence petrography to differentiate two late-stage coarsely crystalline dolomite cement phases within the Swan Hills buildup and platform of the Wild River area. The type and petrographie characteristics of late- stage dolomite cements of the deep subsurface and adjacent outcrops are summarised in Table 1-1. Published Fluid Inclusion Evidence Mountjoy and Amthor (1994) and Mountjoy et al. (1997. 1999) provided fluid inclusion evidence for late-stage dolomites from Upper Devonian buildups in the Rimbey-Meadowbrook reef trend. Temperatures of homogenization are higher than those TABLE 1 2' Auld InClu.lon Anal.,... trom Che L...,.tute Devon* ~rf'ce s-.n Hill. SwIn Hill. WUd Ri~ NlsIlu ANf.' W"""un· Leduc' Ro..__..' (MicH)evon,anl (Mi~pper Devonaanl (Ugper o...on,an) (Upper Devon,an) (Upper QeI,onlan) T~ RMI~(·C) Sal1dle dOlom,le 125to 160 97 to 139 (LST IlaIlIIdl 9910175 9010130 9010130 9710 180 (OOl.1laI*') 17010210 170 10 210 Lale~las 9010126 90t 10 132 (c~n 12410164 14810 HO 130101681~1 T.~(·C) Sad s.llnIIy ~(~N.clftIo) 5adde ~ornrte 21102. 14.11022.9 ILSn 91028 17102. 171024 18.• 10 22. 1 (OOU 221024 22102. l.2e calolas 91021 19.31022.31~ 91013 13.910 19.7 (lNI:ttIClIIC*Il 1· Rosevear (Ml1-Devcman). Kaufman "II. (1990) 12 . 5~ Hill$ (Micl- 10 Upper o.won.an). We'IdI••r w.. (1998) 3 - Nisku Reels (Uœ- Oe\Ionian). And8Bon (1985) ~ • Wabllmun (U~ 08vonlanl. Mou'!tloy il ~im-DihWdj.(1991) • 5· L8lSUC (Upper o.ta'lian). dolomite cs.ta tram ~(19901). c:U:rt. dala 15 tn:m MountioY .,. (1997, 1999) 14 Cllllptt'r 1: GENERAllNTRODUcnON estimated to have occurred in lheir Devonian host-rocks during maximum burial. In the • deep western part of the Alberta Basin, Duggan (1997. Swan Hills Simonette), Green (1999, Kaybob and Kaybob South). and Wendte et al. (1998, Swan Hills and Leduc) have reported a wide range of Th data for saddle dolomite cements (Table 1-2). White the published fluid inclusion database for the subsurface is modest. the evidence published on cements from Devonian outcrop is scant indeed. Geochemistry The geochemical characteristics of late-stage dolomite cements for several basin localities are summarised from the literature in Table 1-3. Machel et al. (1996) reported SiSr/86Sr ratios of between 0.7118 and 0.7152 for late-stage dolomite cements in the Dcvonian Qbed buildup. More recently Duggan (1997) discovered even more 8iSr_rich signatures--in late-dia~enetic dolomites of the Swan Hills Simonette (87Sr/86Sr ratios as high as 0.7336). Green (1999) found 87Sr/86Sr ratios in saddle dolomites as high as 0.7168 in Kaybob. and 0.7224 at Kaybob South. For the Miette buildup. Mountjoy el al. TABLE '-3: Publilhed oeochemlcal charecterlstlcs of la c& dolomite cements. Devonien Alberta 1 Mien. 1 Be~ 1 Swan HiIIs" 1 Leduc· Geochemistry: suc <'-) -0.6 ·3.05 1.77 0.17. 3.08' ÔllO <'-) -9.3 -6.41 -7.84 -8.22. -6.97 F. (ppm) 841 1490 100-10,000 615 Mn (ppm) 74 165 <300 196 Sr (ppm) 96 235 67 nia MgCOI (wt%l 46.8 46.6 nia 49.0 .7SrJ"Sr 0.7107 0.7104 0.7109 0.7085-0.7090 Ave~ depth: 5000 m max 4115 m 3050·3450 m 1600·2500 m 1 • Miette data from Mattes and Mountjoy (1980) and Mountjoy et al_ (1 992) 2· Bearberry data 'rom Laflamme (1990) 3 - Swan Hills data trem Kaufman et al. (1990) 4 • Leduc data from Amthor et aI. (1993) CL - Cathodoluminescence •- Saddle dolomite • •- Other dolomite cements 15 C1uzprt!r 1: GEfI-'ERAL lNTRODUcnON (1992) reponed 87Sr/86Sr ratios between 0.71049 and 0.71084 for two saddle dolomites~ • and 0.70970 for one white sparry late dolomite. Contrary to the deep subsurface, the ~1iette data are lower than values estimated for regional events such as matrix/pervasive dolomitization and do not suggest a strongly radiogenic fluid source for these dolomites. Laie-stage Calcites Commonly late-stage calcites are among the latest phases to precipitate from highly saline brines of the deep basin. These cements are coarsely crystalline, range from euhedral to locally anhedral (Table 1-4). TABLE 1-4b: Types of calcite cementa ln the deep aubaurfKe of the Albertli BuJn. Di~lcStage 1 Ch..lICterlmlc Morphotogiea 1. Syndepositional Radial Fibrous • Fibrous Calcite (submanne & freshwaterlseawater mixiing zone) 2. Subaenal (vadose) MicrostaJaetictic calcite 3. Shallow bunal (phreatic) Fine equant calcite 4. Inrermediate ta deep bunaJ Ccarse equant calCIte (below meteonc recharge] S. Teetomc and post-tectomc Ccarse macrocalcIte TABLE 1-4b: Types of calcite cementa in the MieUe Buildup, Alberta Front Ranges. Diagenetlc Stage 1 CharllCterimic Morphologies 1. SyndepositionaJ Bladed cements. radlaxial fibrous calcite. (submarine & freshwaterlseawater mixiing zone) botryoidal cements (negligible) 2. Subaerial (vadose) Rim cement. granular cements. gravîtational cements. (blocky calcite?) 3. Shallow burial (phreatic) Slocky (equant) calCite. granular cements. bladed cements 4. Intermediate ta deep ounaJ Blocky Calcite (below meteonc recharge] S. Tectonic and posHectonic Coarse bIocky caJcite and scalenohedraI cements Af1ef Mi1lIItS and Mounljoy (1980), • Types" and5 are rtIfI focus (}/ rh:s worff. 16 Cllaptt'r 1: GENERAL INTRODlJC'TION Published Fluid Inclusion Evidence • In the Pine Creek Leduc and Kaybob South reservoirs late calcite samples yield temperatures of homogenisation (Th) that are similar to those from lare-stage dolomite cements, and freezing points (Tm) that show they are generally less saline (Mountjoy et al., 1999. Table 1-2). Preliminary fluid inclusion work on samples from the deep subsurface (Duggan. 1997; Green. 1999; and Wendte et al., 1998) suggests that these calcites wcre precipitated at temperatures suitable for petroleum generation. Geochemistry Based on the existing data. the highest 87Sr/86Sr ratios among late-stage carbonate cements occur in the calcite phases (Table 1-5). Machel et al. (1996) reported 87Sr/86Sr ratios as high as 0.7252 for late-diagenetic calcites from Obed. In the Swan Hills Simonette reservoir. late-calcites with signatures as high as 0.7369 have been ;dentified (Duggan. 1997), and Green (1999) found 87Sr/86Sr ratios in calcite cements as high as 0.7310 at Kaybob South. While the existing data for calcite cements from Devonian oUlcrop are limited. Cavell and Machel (1997) reported 87Sr/86Sr for late-stage calcite cements from Devonian outcrop at Big Hill (0.7086-0.7108) and at Toma Creek (0.7093 TABLE 1-5: Publilhed Isotopie ~ for La• .a.ge c.leite cements. Devonl. DIep AlbeM a-fn. Obecl L8duc' S"HIII.. WUd PlneCrwll PlneCrwk s....HU.. SwMHtUa A'~181ptone1 LHuc' W...... • ~SoutII· SIIIIanea.· (Frasnaanl (laie GMlI.v (L.-~I (Farnmern8l'Il (la! Givell8rV (UIe~ HlISn"'l F,."...,) Fr.II"..,) GeocMmI8Uy: 5"CI'oI 1.12 to -27.1 -7.410 -23.6 ·3.5310 -5.69 -7.25 0.21 ta -12.lU 1_~toO.12 5U O 1'0) -6.5 to -11.87 -9.4 to·1 1.9 -10.65to-11.63 -8.22 -9.38 te -14.51 -9.60 te -12.77 nSr,-as, 0.7086 ta 0.7252 7113100.7235 0.7170 to 0.7195 07187 0.7170 to 0.7310 0.7288 to 0.7369 n. 28 6 2 1 2 8 Approalm'" DIptII (m): 3800 ta 4850 <&270 ta 46SO 35ooto 3600 3IW6 339Oto 3735 3800 to 3900 1 - Patey (1995) 2 - W8ldte.,.L (1998) 3 - Green (1999); Data trom Mountjoy et aL (1999) • 4 - Duggan (1999) 17 Chapler Jo- GENERAL INTROOUcnON to 0.7111). Devonian marine carbonates have 87Sr/86Sr between 0.7080 and 0.7082 • (Mountjoy et al., 1997; Dension et al., 1997). Late-stage calcite cements generally have more negative ôlSO values than the late-stage dolomite cements (Mountjoy and Amthor, 1994; Mountjoy et al., 1999; Table 1-5). Although Devonian marine carbonates have Ôl80 signatures between -2.0 and -4.0 (Mountjoy el al., 1997), late-stage calcites (and dolomites) have ôlSO values that are considerably lighter. General Diagenetic Trends Many studies, including Kaufman (1989), Amthor et al. (1993), Drivet (1993), Marquez (1994), and Drivet and Mountjoy (1997) have placed coarse-crystalline saddle dolomites and the latest coarse-crystalline calcite cements late in the paragenetic sequence. These authors, based on position in the paragenetic sequence, C isotope and fluid inclusion (Th) evidence, contend that these late carbonate phases were deposited dunng deep bunal (i.e., > 2000 m), because such high temperatures have been shown to have occurred only late in the bunai hislory. In a study of the Devonian Swan Hills platform and bank carbonates in the Wild River acea, Wendte et al. (1998) suppon a Iate genesis of coarse-crystalline saddle dolomite cement, followed by precipitation of late calcite cement. However, based on fluorescence petrography, they distinguish between two phases of dolomites, with the first (matrix to saddle or euhedral, dominantly replacement) reflecting a heating phase followed by cooling, prior to burlal by the Mesozoic clastic wedge. The second phase saddie dolomites precipitated sometime in the Cretaceous to Eocene dunng the evolution of the foreland basin. • Based on existing research and data, the following general diagenetic sequence 18 Cllaptt'r 1: GENERAL INTRODUCTION for the Leduc subsurface is evident: l - carly marine cements (+/- exposure) • 2 - replacement dolomite 3 - dolomite cement 4 - saddle dolomite (1 or 2 phases?) 5 - calcite 6 - anhydrite 7 - bitumen While Nesbitt and Muehlenbachs (1997) presented substantial fluid inclusion and isotopie data for veining in late Proterozoic strata exposed in the southeastem Canadian Cordillera, relatively liule evidence has been published for the late carbonate cements of Devonian strata in the Front and Main Ranges of the Rocky Mountains. ~fattes and Mountjoy (1980) examined burial diagenesis in the Upper Devonian Miette buildup. Jasper National Park. (Tables 1-4 and 1-5). Melim et al. (2000) contend that most of the white dolomite found within the Miette buildup is replacement rather than cement, and do not differentiate between this phase and the pressure solution dolomite identified by t\1attes and Mountjoy (1980). Melim et al. (2000) put the formation of saddle dolomite at the end of the paragenetic sequence for Miette. but late calcite cements clearly post-date saddle dolomites (see Mattes and Mountjoy, 1980). Using the existing research in combination with the analyses perfonned in this study. a general paragenetic sequence is presented in Chapter 3 {Fig. 3-2, section 3.2) for these Devonian outcrops. Metbodology Samples Ten late-stage calcites and one saddle dolomite from Leduc cores at Qbed (patey, 1995: Machel et al., 1996) were studied. Five late-stage carbonate cements from molds • and vugs (3 calcites and 2 saddle dolomites) were studied from Swan Hills Simonette 19 Chaplt'r J: GENERAL INTRODUcnON cores. The sixteen subsurface samples studied are from core sampled by Patey (1995) • and Duggan (1997) in Calgary at the Core Research Centre of the Albel1a Energy and Utilities Board. Fluid Inclusion data presented in this thesis from Obed are the only microthennometric evidence published for late-stage cements from this reservoir. and those from Simonette expand on the limited tluid inclusion analyses repol1ed by Duggan (1997). Late-stage fracture and vug-fïlling cements in Devonian carbonates of the Front and Main Ranges of the Rocky Mountains were also studied following an extensive sampling campaign by the author. Sixteen samples from nine outcrop locations are included in this study. Eleven of these (8 calcites. 2 saddle dolomites. and 1 dolomite cernent) have been subjected to both tluid inclusion and geochemical analyses. Isotopic data only (i.e.. 87Sr/86Sr. Ô13C. a180) are presented for samples from Mannot Cirque and Rice Brook. The data presented in this thesis from outcrops significantly increase the size and scope of existing tluid inclusion and isotopic evidence for late-stage carbonate cements exposed in Devonian strata of the Front and Main Ranges. Auid inclusion and geochemical data for aIl samples are Iisted in Appendices A and B. PetrograDhv Doubly-polished thin sections were examined using a petrographic microscope with diffused light and a blue-light epitluorescence microscope (480 to 520 um). Half of each thin section was stained with Alizarin red-S. Cathodoluminescence of selected samples \\'as examined using a Nuclide Luminoscope, Mode1 ELM-2. • Cathodoluminescence petrography was carried out with a beam voltage of 16 KV and a 20 CIlaplU J: GENERAL INTRODUCTIQN beam current of 0.5 mA in a 40-50 mTorr vacuum under an air atmosphere. The aspect • ratio of ail photos and slides has been maintained during reproduction. Fluid Inclusion Analyses Fluid inclusions in late-calcite and late-dolomite cements were analysed by the author and Prokopis Kranidiotis using an adapted United States Geological Survey Gas Flow Heating and Freezing System (Were et aL, 1979; Hollister et aL, 1981) at McGill University. The melting temperature of ice was converted to weight percent Nael equivalent using equations in Oakes et al. (1990). Ali data are Iisted in Appendix A, Tables A-l to A-3. A general discussion of tluid inclusions and the analytical techniques employed in this work is presented in Appendix C Isotope Analvses For the Obed samples (Patey, 1995), strontium isotopie analyses were measured at the University of Alberta according to the methods of Baadsgaard et al. (1986). with a precision better than 0.00005 (20). Using the methods described in McCrea (1950) and Epstein el al. (1964). ôlSa analyses of Obed samples were carried out at the University of Calgary, Department of Physics. The precision of Ôl80 measurements is ± 0.8 %c (Patey. 1995; Machel et aL. 1996). Additional carbon and oxygen isotope analyses for bath the outcrop and Swan Hills Simonette samples was performed at the University of Michigan. Ail isotope data are listed in Appendix B. Strontium analysis of outcrop samples was carried out at the Université du Québec à Montréal by Helene Isnard, under the supervision of Dr. Ross Stevenson. and have a precision better than 0.00003 (20). • Samples were prepared at McGill University. 21 Chaptl'r J: GENERAL fNTRODUcnON Tbesis Organisation • Data from subsurface samples are summarised and discussed in Chapter 2 and data from outcrop samples in Chapter 3. The first part of Chapter 2 focuses on Obed. and the second part centres on the Simonette buildup. Summary and conclusions are presented in Chapter 4. Appendix A lists data from f1uid inclusion analyses canied out on subsurface and outcrop samples. Appendix B contains isotopie data from subsurface and outcrop samples. Criteria for the identification of primary fluid inclusions and the need for pressure correction of f1uid inclusion data are discussed in Appendix C. Acknowledgements This research was supported by funds from Natural Science and Engineering Research Council (NSERC) and Lithoprobe grants to E. W. Mountjoy. We appreciate discussions and infonnalion from Pat Cavell and Hans Machel conceming Qbed samples and data. and discussion on tluid inclusion techniques with A. E. Williams-Jones. ln addition. useful discussions with Darryl Green and James Duggan regarding fauhing in deep basin Devonian reefs near. and isotopie and fluid inclusion data from Swan Hills Kaybob South and Simonette buildups. are greatly appreciated. 1 would Iike to thank the Albena Energy and Utilities Borad for their very efficient and friendly service. Thanks to George Pangiotidis for thin section preparation. Prokopis Kranidiotis for help with fluid inclusion analyses. and Graham Dolce for help with photography. computer drafting and general logistics. Thanks to Annick Chouinard for her help with the translation of the Abstract into French. 1 would especially like to thank Professor Emeritus Eric Mountjoy for sharing with me his unique knowledge of the Alberta Basin and the eastem Rocky Mountains. It has been my honour and a pleasure to work with such an accomplished• • committed and enthusiastic scientist. 22 CHAPTER2 • FLUID INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS DEVONIAN STRATA, WEST-CENTRAL ALBERTA SUBSURFACE Fluid inclusion evidence for late-stage diagenetic cements are presented in this chapter from the subsurface portion of the Southesk-Cairn reef complex. at Obed and from the Swan Hills Simonette. in conjunction with geochemical data from Patey (1995) and Duggan (1997). Fluid inclusions in 3 late-stage saddle dolomite and 13 calcite samples were studied from wells in the Leduc Obed and Swan Hills Simonette buildups in arder to constrain the timing of their formation. Many of these late-stage calcite and dolomite cements have very high 87Sr/86Sr ratios (as high as 0.73697). and their origin and timing remains unceI1ain. Sorne tluid inclusion measurements. by Duggan (1997). were done on a small number of late dolomite and calcite cements from the Swan Hills Simonette reservoir. Wendte et al. (1998) reported tluid inclusion evidence for carbonate cements in the Swan Hills platform and bank carbonates of the Wild River area. Recently. Green (1999) completed a study of tluid inclusions from Kaybob South. Kaybob East. as weil as Pine Creek (Leduc and Wabamun). Presently. no tluid inclusion data have been published for late-stage cements from Leduc strata of the Obed buildup. The Obed buildup is the focus of the first half of this chapter and the Swan Hills Simonette is examined in the latter half. For each of the two subsurface study areas, sections on stratigraphy and platform geometry, paragenesis, and petrography precede tluid inclusion and isotopie evidence. A discussion of the burial history of these deep • basin reservoirs concludes the chapter. Chapter:!: FLUfO rNCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - pEEP SUBSURFACE OBED • Stratigraphy Carbonate cements were collected from strata in the Upper \Voodbend Group (Leduc Fonnation) and the overlying Upper Winterburn Group (Blue Ridge Member). These successions contain cycles of reef to basin transitions that fonn westerly thinning wedges of sediment (Patey, L995). Late Devonian deposition and buildup stratigraphy were controlled by superimposed short-term and long-term tluctuations in relative sea level (McLean and Mountjoy, L994). The Devonian stratigraphy of the Obed buildup is similar to that found in the Front Ranges. with the NiskulArcs resting directly on the Leduc/Peechee and not separated by the Ireton shale. as it is funher east in the basin (Mountjoy. L989). The geometry of the Obed Platfonn is illustrated along cross-section A-A' (Fig. 2- L) from Patey (1995). The present-day depth to the base of Wabamun strata (Fammenian) in the Obed area varies from about 4000 to 4600 m (northeast to southwest. respectively: see Fig. 2-1 and Table 2- L). A more detailed schematic cross-section illustrates the morphology and stratigraphy of the Qbed Reef complex (Figs. 2-2a and b). An inferred syndeposiùonal fault separating wells 15-26-54-23W5 and 11-35-54-23W5 is shown in Figure 2-2a (from Patey. 1995). An alternative interpretation is shown in Figure 2-2b with no fault separating these two wells. Although none has yet been documented at Obed. post-depositional faults like that inferred in Figure 2-2a have been positively identified in the deep basin within the Swan Hills Simonette (Duggan. (997). Kaybob South and Pine Creek (Green. 1999) fields. • 24 Charra 1: A..UID INCLUSIONS lN LATE·STAGE CARBONATE CEMENTS - pEEP SUBSURFACE • Figure 2·1: Stratigraphy of Obed area~ deep basin~ along cross-section A-A', see Figure 1-4 for location. Absolute ages Iisted are from the aSA (1983) Decade of North American Gcology (DNAG) publication series. • 25 Figure 2-1 • FOR~.MTlON AGE OEPTH NAMES (Ma) (m) 1000 Paskapoo & Upper Scollard 66.4 --l:"--~ C - Q5eaLsvel ni ;: ~ u Lower Scollard ~ ni'" ni :2 74.5--~! Bearpaw -1000 ::1'" .,o u Belly River S ! u Lea Park & - -2000 Colorado Group MANNVILLE GROUP 144.0~-~ :080 J30.0~-"""'- -3000 RUNOLE GROUP ë BANFF -:1 EXSHAW ni 360.0--'U WABAMUN c --~~~~ --"ë• 'MNTERBURN GROUP o --~ WOOOBEND------GROUP 408.0 Q -4000 570.0 C.mbria - Precambria • C/rarra :!: FLU ID INCLUSIONS IN 1--\TE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figures 2-2a and b: Schematic SW-NE cross-sections across the Qbed area showing gas/water contacts in the Leduc, Nisku / Blue Ridge sour gas pools. Upper parts of buildups \Vere assigned by Patey (1995) to the Blue Ridge, but they could be Nisku equivalent. Figure 2-2a depicts Patey's hypothesis that a post-depositional fault may occur between wells 15-26-54-23W5 and 11-35-54-23W5. An alternative interpretation without a fault is shown in Figure 1-2b (see tex.t for details). • 26 • Figure 2·2a sw NE 5-13·54-23W5 6-24-5-4-23W5 '5-26-~23W5 8-t·55:-23W5 lG-9-55;22W5 7-6-~·22W5 tt.13·~23W5 9-23·5:4-23W5 11·35-~-23W5 8·6-55-23W5: Anet' Paley 11995) Figure 2·2b sw 5-t3·S4·23W5 6-24-54-nw5 t5-26-~23W5 8-1.55:23W5 lo-9-55:22W5 7-6-~.22W5 ".'J.~.23W5 9-2J.5:'-23W5 ".J5.~.2JW5 8-6-55-23W5· • Chapter 1: FLUID INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2·3: Paragenetic sequence for Frasnian Devonian strala. Obed buildup (after Patey. 1995). • 27 • Figure 2-3: PARAGENETIC SEQUENCE (OBED) DIAGENETIC EVENT EARLY LATE 1 1 Earty calcite cements 1 .- 1 1 Bacterial sulphate reduction, 2 gypsum/anhydrite formation, ____ L ____. pyritization 1 1 1 3 Fracturing 1 1 ••• 1 .- 1 , 1 1 l ••••• ._. 4 Stylolitization ·r··· ! 1 1 ••••• 1 ••••-1 5 Replacement dolomite 1 1 t 6 Fracturing Il 1 1 ....-...-1 ._..- •• 7 Planar dolomite 1 1 1 1 ______8 Anhydrite cementation 1 and replacement 1 1 1 ••• 1 9 Hydrocarbon migration 1 1 1 • 1 10 Bitumen 1 1 1 • 11 Saddle dolomites 1 1 12 Calcite cementation and/or dedolomitization ~.-r-' 13 Pyrite mineralization 1 .. 1 14 Native Sulphur 1 1 ._.-1 ~ 15 Fracturing III 1 .. .. 1 1 SEA SHAlLOW INTERMEDIATE DEEP FLOOR BURIAL BURIAL BURIAL 1 eOOm, 2000mJ toY toY 1000m 3000m • C1/l1pr~r 1: RUfO rNCLUSfONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE T_ble 2-1: Stratigrapf'ly Ac:roa Obed -"-_ SW-NE (cr....-clion A to A', Fia. 1-5) 1I7.1.a-,.... :lW 1(.(111): 11-.7 ".- Ne 1(.(1111: lZ1~ TOPS IUII"~ DOWNtClU DU ~C.· nEJOlE.1tlI ....aP'H ~DU nEJOlE.c. ~(Ill KNHT 380.1 836.1 812.3 2665.2 BEAAPAW -488.3 1675 235 771.0 8ELLYAIVEA -723.3 1910 411 1348.5 -432.2 1648.4 384 1259.9 LEA PARK • WPIB PKKU -1134.3 2321 219 718.5 -816.2 2032.4 125.6 412.1 COLORADO -1353.3 2540 -941.8 2158 BAD HEART -1472.3 2659 -1075.3 2291.5 MSKK -1503.3 2690 -1098.1 2314.3 CADZ -1569.3 2756 -1163.4 2379.6 CAROIUM -1611.3 2798 -1199.3 2415.5 KSKP -1648.3 2835 -123~.~ 2450.6 BLCK SSPK -1865.3 3052 -1392 2608.2 DUNVEGAN -1563 2779.2 SFBR -1598.6 2814.8 8FS -2164.3 3351 -1656.8 2873 VIKING -2195.3 3382 JOLI FOU -2198.3 3385 847 2779.0 749.2 2458.1 MANNEVILLE -2200.3 3387 PCGP -1691 2907.2 HAMN SPRV -1706.5 2922.7 BLSK -2474.5 3661.2 -1940.9 3157.1 GTNG -2482.5 3669.2 -1944 3160.2 CAOOMIN -2627.7 3814.4 -2069.5 3285.7 NKNS ·2632.2 3818.9 449.9 1476.1 386.5 1268.1 FERNI -2650.2 3836.9 -2077.5 3293.7 ROCK CREEK -2694 3880.7 POKERCHIP -2707.6 3894.3 NORDEGG -2724.1 3910.8 125.9 413.1 -2123.8 3340 94.5 310.1 MNTN -2776.1 3962.8 -2172 3388.2 ELKTON -2876.1 4062.8 -2253.3 3469.5 SHUNDA -2961 4147.7 -2286.3 3502.5 PEKISKO -3021 4207.7 281.9 924.9 -2368.6 3584.8 233.4 765.8 BANFF -3058 4244.7 -2405.4 3621.6 EXSHAW -3223 4409.7 -2574.9 3191.1 WABAMUN -3225 441'.7 405.9 1331.8 -2577.3 3793.5 282 925.2 WINTERBURN -3463.9 4650.6 CALMAR -3516.8 4703.5 -2859.3 4015.5 NISKU -2865.1 4081.3 WOLF -3519.3 4706 CYNTHIA -3598.8 4785.5 ZETA LAKE -3603.8 4790.5 205.4 673.9 78.9 258.9 IAETON -2938.2 4154.4 LEDUC -3669.3 4856 NIA NIA -2956.5 4172.7 NIA NIA TERTIARY & 1186.5 5861.5 1086.1 3563.5 MAASTRICHTIAN TOTALDEPTH 4967.5 16298.4 4232.5 13886.8 Source: Accumapnt Paragenesis A paragenetic sequence for the Obed buildup, determined through petrography and visual examination of core, is summarized and modified from Patey (1995) (Fig. 2- 3). Late phases affecting reservoir quality include dolomite and calcite cements, with • secondary anhydrite, sulphur and pyrite also contributing to the filling and destruction of 28 Charrer 1: A.UlD INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE porosity. The studied carbonate cements precipitated during late burial diagenesis (as • defined in Chapter 1, section 1.3) when Devonian host strata were buried more than 2 km deep (events Il and L2. Fig. 2-3). Late-stage calcite and dolomite phases are distributed throughout the Woodbend and Winterbum Groups of the Obed platform in similar abundances (Patey. 1995). Late-calcites post-date and are sometimes in corroded contact with late-stage saddle dolomites (Patey. 1995). Petrography Fluid inclusions were studied in II samples from 8 wells in the Qbed buildup (Fig. 1-5). Ali are late-stage cements: 1 saddle dolomite and 10 calcites. Ail are from Upper Devonian strata whose present depths range from 3977.4 to 4824 m (Table 2-1). The calcite cements studied tïll fractures or vugs (Plate lA and 8). These lale diagenetic phases precipitated within brecciated zones and appear to postdate stylolites (Plate lA and C. respectively). These cements analysed are composed of crystals that range widely in size, from medium to very coarse (500-4300 J.Lm). Crystals are rarely anhcdral and commonly subhedral to euhedral. The calcite phases studied are limpid to translucent. commonly twinned (Plate 2A), and do not tluoresce under blue light. Saddle dolomite (non-planar) was found in three samples (7-1-53-24W5. 14-23 53-23W5. and 11-35-54-23W5 at 4225.1 m); however microthermometric analysis was only possible for one sample from weIl 14-23-53-23W5. This sample consists of the corroded remnants of very coarse (2500-5400 J,lm), euhedral. and translucent crystals that fill a yug (Plate 2B). The other two samples a1so contain these saddle dolomite remnants • along vug walls (7-1-53-24W5 and 11-35-54-23W5), but do not contain enough material 29 Ouzpra1: Rum INCLUSIONS IN LAIE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE for tluid inclusion analysis. Traces of bitumen along the margins of corroded saddle • dolomites were detected in one of the samples not subjected to f1uid inclusion analysis. indicating that these dolomites predate bitumen. These late-stage saddle dolomites tluoresced to a dull yellow-green under blue light. Fluid Inclusion Description There is a wide range of sizes of calcite primary tluid inclusions (3 to 15 J,1m by 5 to 20 J,1m); whereas. dolomites contain smaller inclusions (~ 7 by 7.5 J,1m). Primary inclusions within these cement samples are two phase, Iiquid-vapour (L-V) filled. Their L-V ratios (F) are largely consistent at F = 0.90 (Plate 2C). Only a few inclusions lack vapour and are interpreted to be secondary (see Appendix C for a discussion on the differentiation between primary and secondary inclusions). The tluid inclusion assemblages' (FIAs) consistent L-V ratios (i.e.• 0.9) and their small bubble sizes (i.e., -10% of inclusion volume) indicate that these primary inclusions were fonned at elevated temperatures (Goldstein and Reynolds. (994). The small vapour bubbles were generated during uplift and cooling to surface temperatures and pressures. Homogenization Temperature (T.J Data Homogenization temperatures were obtained from 152 inclusions in 1 dolomite and 10 calcite samples (Fig. 2-4). The data, uncorrected for pressure, (see Appendix A. Table A-I) reveals a bimodal distribution of Th data for the RA studied. Most have Th between 127 and 152°C (Th" Fig. 2-4a). constituting about 75% of the total dataset, • while a second group of inclusions have homogenization temperatures between 154 and 30 ClliJptu 1: R..UID lNCLLTSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE 172°C (Thl. Fig. 2-4a). While many Th2 inclusions are situated nearer crystal margins • (versus Thl), sorne are not, and no paragenctic or texturai distinction has been established between the host cements for Thl and Th2 inclusions. This evidence suggests that at least sorne of the inclusions in the assemblage yielded a Th datum above the formation temperature of the host phase. likely as a result of stretching (see Appendix C). The average Th for ail inclusions tested in this calcite is 146.SoC and the average salinity is 19.7 weight percent NaCI equivalent. Inclusions in the single saddle dolomite yield an average homogenization temperature of 142.1°C (0 = 11, Fig. 2-4b). close to that of the calcite cement (l41.7°C. n=ll) tïlliog most of the vug in which the dolomite grew. The average Th for each sample is plotted on a map of the Obed buildup (Fig. 2-5). A plot of average Th versus present-day burlal depth (Fig. 2-6) reveals a large scalter with a very weak positive correlation between increased burial depth and homogenization temperature (i.e.. 0041). Assuming that these late-stage cements were probably deposited near maximum burial depth. the samples need to be pressure corrected (see Appendix C for methodology). After correction, they plot near a geothermal gradient of about 20°C/km (Fig. 2-6). Three of the calcite samples came from the same weil (l1-35-S4-23WS at 4211.3. 421S.1 and 4225.1 m; Fig. 1-5). These three contain coarsely crystalline late-calcite cements that precipitated along stylolites and exhibit a positive correlation between homogenization temperature and burial depth (i.e., 0.98). Freezing Point Depression (Tm> Data • The salinity of the inclusions studied ranges from 16.9 to 21.9, and the average 31 Chaerer 1: FLU ID lNCLUSIONS IN LATE-STAGE CARBONATE CEMENTS DEEP SUBSURFACE • Figure 2·4a: Frequency distribution of homogenization temperature data, based on 10 calcite samples from Obed buildup and 140 individual measurements. The bulk of inclusions measured have a Th between 127 and 152°C (Thl. mean = 142.2°C). Most of the samples contain a second population of primary inclusions (Th2 =154 - 172°C. Mean =163.0°C). Data are presented in Appendix A. Table A-1. Figure 2·4b: Frequency distribution of homogenization temperature data, based on a single saddle dolomite samples from Obed buildup and Il individual measurements. The inclusions measured have a Th between 136.3 and 148.0°C (Thmean = 142. 1°C). Data are presented in Appendix A, Table A-l. Figure 2·4c: Frequency distribution for salinity measurements from late-stage calcite cements. Qbed buildup (mean =19.8 Wt. % NaCI, n=69; Appendix A, Table A-l). 8 of 10 samples contained inclusions of similar salinity (i.e., average Tm is between 19.6 and 21.0 Wt. % NaCl). The remaining two samples contain inclusions that are less saline (between 18.0 and 18.6 Wt. % NaCl). Salinities were calculated from freezing point depression data using the equations in Bodnar (1992). Figure 2-k1: Frequency distribution for ail salinity measurements from late-stage saddle dolomite, Obed buildup (mean = 20.8 Wt. % NaCI, n=7: Appendix A. Table A-l). • 32 FiVu" 2~a: FrwqUllnc:y DlatrlbuUon of T" Data for Obed c.le.... • 30 04-- _ ti' .....0. Homoeenlullon Temper....,. <-CI Figure 2~b: FreQuency EH.crtbutlon of T" Data for Obed Sadd" Dotom... :1 1J 1 '::!i ,l o~------à? ..:~ Homog.nlzadon Tempe,.aura rel ::r Figure 2~c:: Frequenc:y C15tribution of S.lInlly Cata for Obed Cale". -J 1 1 ! '1 J r ~~~~~~~~~~~~~~~~~~~~~~~0 ...... ------s.IInlty (Wl.' ...cl) Figure 2~: FreQIMncy o.ltIIIutiDn of Salnly Data for OlMet SMId. DoIom'" 5 1"",------ ~ J ~ .:1 .cr ~ :1 l1li___.__. ~~~~~~~~~~~~~~~~~~~~~~~ • .....Ily (Wl.% NlCI) ClIilNt'r 2: RUID INCLUSIONS rN LATE~STAGE CARBONATE CEMENTS - pEEP SlIBSURFACE • Figure 2-5: Depth and average pnmary tluid inclusion homogenization temperatures for ten late-stage calcite and one saddle dolomite cements. Data are presented in Appendix A. Table 6. Means ofTh1 range from 136 to 146°C and ofTh2 range from 157 to 167°C. Figure 2-6: Average homogenization temperatures of lale-stage calcite cements ploued versus present and calculated maximum bunal depth. The raw Th data is plotted twice: versus present sample depth and calculated maximum burlaI. It is estimated that 2700 m of Uppennost Cretaceous and Teniary strata were eroded from this area (see text). A third set of data points represents the pressure corrected Th data (assuming a HzO-NaCl tluid). Points plot near a 20°C/km geothermal gradient (l5°C surface temperature). See Appendix C for discussion on pressure correction. Three of the calcite samples (hollow circles) came from the same weil (11-35-54-23W5 at 4211.3, 4215.1 and 4225.1 m; Fig. 1-5). These three contain coarsely crystalline late-calcite cements that precipitated along stylolites and exhibit a positive correlation between homogenization temperature and bunal depth (i.e., 0.98). • 33 • T55 Calcites! o 5 1 ,I! (km) •• SlIddIe DokJm/fe 1 ;::::::==:~! 1 [l""1llesl o 3 Figure 2~: Th vs. Present and Assumed Maximum Buria. Depth for Late-sÙlge Calcites (OSED) 8500 .,..------=------. ! 7500 j -• ~~. ~--o- ----0·- ~ •• a ~ • ConweUon p 0 frO 0 -,",lied '; ____ ~. __ ~.____ _ .. 0 _ '§ 6500 ID E ~ E 1 -; 5500 1 a -·1 ~ 1 1 ~ J 4500 1 3500 ..L.- .....c::~ --l1 100 110 120 130 140 150 160 170 180 190 200 • HomogenlAtion Temperaturw (Til ln ·C) ClJaplt'r:: FlUIO INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - OEEP SUBSURFACE • Figure 2·7: Sample locations of late-stage calcite cements showing depth and average salinities in Wl. % NaCI equivalent. Data are listed in Appendix A, Table A-l. Figure 2·8: Obed buildup late-stage calcite cements, average homogenization temperature versus freezing point depression. • 34 Figure 2-7: Average Fluid Inclusion Salinity - Obed • R24 W5M R23 R22 R21 Calcites o 5 l , i! (km) :•- Sadd. DoItJtrtb 1 ;==~i [mllesl o 3 s Figure 2-8: Tf1 vs. Tm for Obed Sampi•• 1 1 1 1 1 1 -6 1 1 ~ 1 1 1 Ê -8 1 ~ 1 1 1 ! ~ ·10 o ! .. 1 ! -12 i ~ • 1 c!_ -14 1 1 • • 1 ~ _4'.J.~ .... • "0 ~ 1 • _: 1 r; -16 . •• ~ "1' 1 -1.· 1 N ~4 ••• .:-1 ~~r·. • 1 : -18 ! - .: ; .4 ' .. -20 1 ...• 1 1 -22 1 100 110 120 130 140 150 160 170 180 190 200 210 220 • HornogeniUtioft T.mperatu,. CT110 -C) Clrnera 2: R.um INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE salinity of inclusions in ail samples is between 18.0 and 21.0 weight % Nael (Fig. 2-4c • and d. Table A-l, Appendix A). Two of the calcite samples (7-15 and 11-35-CC, Fig. 2 8) have trapped fluids that are slightly less saline, 18.0 (n=15) and 18.6 wt% NaCI (n=12), respectively. These samples have the coarsest crystals among the Obed late calcites. The average salinity of the saddle dolomite (n=7) is 20.8 wt% NaCI (Fig. 2-4d). There is no correlation between freezing point depression and homogenization temperature (Fig. 2-8). Salinity increases slightly with present burial depths, but the correlation is weak (Fig. 2-9). Isotopie Evidence The Obed late-stage calcites studied have very high 87Sr/86Sr signatures (as high as 0.7252), as reported by Machel et al. (1996 and 1999) (Fig. 2-10). When ail available data for the Obed area are plotted versus longitude (i.e.• Range), 87Sr/86Sr exhibits a strong east to west increasing trend on a local scale (Fig. 2-11a); but no north-south trend with Township (i.e.. latitude) is evident (Fig. 2-11b). The trend of decreasing 87Sr/86Sr values eastward away from the western margin of the buildup supports the hypothesis that it may he fault controlled. 87Sr/86Sr signatures also appear to positively correlate with 18 buriai depth (Fig. 2-12). Also, samples high in S7Sr generally have Iighter a 0 signatures (Fig. 2-14a). A plot of a13c and a180 data from Patey (1995) for Qbed late-stage carbonates (Fig. 2-14b) illustrates that Obed late calcites have consistent Ô180 between -6 and -12 (n=49), but exhibit a wide range of al3c (i.e., 1 to -27). Two distinct groupings occur in • the data. The three dolomites and a large group of calcites have signatures that are 35 Chaptt'r 1: FLUm INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2·9: Present burlal depth Obed versus average salinity, calculated from average Tm of tluid inclusions. Figure 2·10: 87Sr/86Sr for late-stage calcites, Obed area. Data are from Machel et al. (1996). Ooly the samples of this study are shown. See Figure 2-11a for complete data set. • 36 Figure 2-9: Salinity vs. Present Burial Oepth - Obed • 21.5 ~------. :> 21.0 's • g- 20.5 • • • u • ~ 20.0 - • (/!. 19.5 • • ~ >. 19.0 :5- 18.5 • enta 18.0 • 17.5 3900 4100 4300 4500 4700 4900 Present Burial Oepth (m) Figure 2-10: 17srl"Sr Values - Obed R24 W5M R23 R22 R21 s o 5 ! l , 1 ! 1 (km) 1 1 (milesl o 3 • C/Ulpra 2: FLUID INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - pEEP SUBSURFACE • Figure 2·11a: 87Sr/86Sr versus Range, Obed buildup. All available data (Machel et al., (996) for late-stage calcite and dolomite cements. Figure 2-11b: 87Srl~6Sr versus Township for Devonian late-stage calcite and dolomite cements, Obed buildup. Data are from Machel et al. (1996). • 37 Figure 2 11 a: - 0.726 ! 1 1 • 1 1 • 1 • 1 1 1 • • 0.722 • • • • • • 0.718 1 1 1 • • 1 • ! • 1 - 0.71~ i - - i 1 • 1 1 • 1 • t .li. 1 • 0.710 1 • 1 • i 1 1 • 1 1 :• calcites A dolomites 1 1 1 1 i ! 1 0.706 56 55 54 53 52 WEST RANGE EAST Figure 2- 11 b: ons ! 1 : • i • 1 1 1 1 i i 1 • ! • 0722 1 • 1 : • • 1 1 • 1 1 • ! • • 0.718 ! • i • 1 1 A • 1 ! - - 0.71~ • • • 1 .li. • 0.110 ! • 1- • 1 i• calcites A dolomites 1 1 i 1 0.706 56 55 54 53 S2 • NORTH TOWNSHIP SOUTH ClUlptt'r 2: R.UID INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSlJRFACE • Figure 2·12: 87Sr/86Sr values for calcite and dolomite cements from the Obed buildup plotted versus present day burial depths (data from Machel et al.. (996). Figure 2·13: B13C data for calcite and dolomite cements from the Obed buildup plotted versus present day bunal depths (data From Machel et al., 1996). • 38 • Figur. 2·12: 17S,"'Sr v•. Pr•••nt Depth for Ob.d Sample. 3500 ) 1 1 1 • • 1 • , • .. 1 i 1 1 • 1 -••. r"" • ... ·1 4 • J • • .. ' 1 • 1- •1 • ! l : 1 1 1 1 : 1 • •• ! 1 l1 , 1 1 : 1. Cale.11lS • DoIonutllS 1 1 • 1 1 , 1 : 1 1 1 • 1 1 1 1 i 1 ! 1 1 1 1 1 1 5000 1 0.706 0.708 0.710 0.112 O.7'~ 0.716 0.118 o.no 0.7'Z2 o.n~ 0.726 I7Sr'-Sr Figur. 2·13: aUc vs. Pr.ent Oepth for Obed Sampi•• 3500 1 i 1 i ! 1 .1 1 1 1 e • 1 1 1 ~ e 1 1 1 - • ~ •• .. J.. 1 • 1 • • 1 ~ •• •1 .. ,~I àI.à 1 Walerlevel . .• ··1·· e. •- al Dme of 1 • di$COVery i 1 • 1 1 1 1 • e • i 1 1 i 1 1 leCalCltes ~OoIomltes i 1 1 1 • 1 1 • • • 1 ! ~ 1 5000 i ! 1 .JO ·25 ·20 .15 .10 ·5 o oUC{'JI.. POe) • Clutptt'r 2: FlUfO INCLUSIONS lN tATE-STAGE CARBONATE CEMENTS - OEEP SUBSURFACE • l8 Figure 2-14a: 87 Sr/86Sr versus a 0 for Devonian Leduc and Nisku late-stage carbonate cements, Obed (data From Patey, (995). Hollow circles represent calcite samples included this sludy. Figure 2-14b: Sl3e versus 5180 for Devonian Leduc and Nisku late-stage carbonate cements, Obed (data From Paley, (995). Hollow circles represent calcite samples included this study. • 39 • Figure 2-14a: 17Sr'-Sr VI. 8'10 - Obed 0.726 0.720 •• .'. CALCITE 11S,r"S, • •• 0.716 Il.1).54-23w5 .a. (40122ml •• DOLOMITE • • 0.712 •••• •• •• 0.708 •• ·20 ·16 ·12 .a o .5 "0 r-. POS) 5 o ,..• • ••• •••• • •• ·5 -: . . 1.1~S2·2406 ~ 1482JJmI -10 s"c (%e. POS) • •• -15 ,.... • • •• • • -20 •• • • ·25 t1"~2:M5 .0 (< -30 -20 -16 ·12 .a -4 o at'or- POS) • ChaDra 1: FLUiD INCLUSIONS IN L-\TE·STAGE CARBONATE CEMENTS - DEEP SUBSLJRFACE 1 markedly heavier (i.e., at least +4.5%0 PDB ) than a second group of calcites that yielded • oJ3e between -11.4 and -27.1. Patey (1995), however, makes no paragenetic or texturaI distinction between the calcites of these two groups of signatures, and none was found in those analysed in this work. Three of the calcites in this fluid inclusion study are represented in the two data c1usters (see Fig. 2-14b). The light ô13e of the Obed calcites suggest formation in a reducing environment, and are evidence that the reservoir has been at very high temperatures (i.e., >120 or 140°C) for sorne time. Il is at these elevated ternperatures that reduction of sulfates (TSR) is known to accur in buried reservoirs (see discussion of TSR by Machel, 1998). A plot of (5 13e versus depth shows the lightest signatures occurring near the top of the Obed reservoir. probably reflecting the fact that TSR only occurs above the water level (Fig. 2-13). Other workers. such as Drivet and Mountjoy (1997), have made similar interpretations. SWAN HILLS SIMONETTE Stratigraphie data of the Swan HiUs Simonette buildup are summarized from Duggan (1997) who investigated the geology and diagenesis in detail. Preliminary f1uid inclusion data from the Swan Hills Simonette were presented by Duggan (1997) for 4 late calcite and 2 saddle dolomite samples. An additional five samples are presented below, followed by a review of isotopie evidence and discussion ofthe local burial history. For the Swan Hills Simonette area general lithologies and stratigraphy of the Heaver Hill Lake Group are presented in Figure 2-15, while a more detailed picture of the • 1 Ail carbon and oxygen isotope data presemed in this thesis are in %0, PDB (Peedee Belemnites). 40 C1rapra~: FLUID INCLUSIONS lN LATE-STAGE CARBONATE CEMENTS - DEEP SURSURFACE entire stratigraphie succession and depths to fonnation tops across the buildup is shown • in Figure 2-16. Present burial depths for the Swan HiBs Simonette reservoir are between 3750 and 4000 m. Paragenesis Fluid inclusions were studied in 5 samples from 3 wells in the Simonette buildup (Swan Hills Fonnation) (Fig. 1-6). Ali are late-stage cements; 3 calcites and 2 saddle dolomites. from Devonian strata whose present depths range from 3725.0 to 3909.8 m. Calcites. at Simonette. were fonned prior to late dolomite cementation. Duggan (1997) assigned calcites at Simonette that formed prior to late dolomite cementation to an intermediate burial environment. They are petrographically similar to the late-calcites. The paragenetic sequence (Fig. 2-L 7) for the Swan Hills Simonette field. summarized from Duggan (1997), indicates that saddle dolomites overlap with and are postdated by late-diagenetic calcites). Petrography The late-diagenetic calcite cements fill or partially fill moldic and vuggy porosity in replacement dolomites (Plate 3A and B). Calcite crystals range from fine to very coarse (800-4000 J-lm). subhedral to euhedral. Iimpid to translucent, are commonly twinned. and do not tluoresce under blue Iight. The saddle dolomites (non-planar) are coarsely-crystalline (600-3200 tlm), translucent, and vug-filling (Plate 3C). Under cathodoluminescence samples show strong zonation of up to 12 aJtemating duUer and brighter zones. Staining reveals up to five strong blue zones suggesting that the duller • zones are ferroan. One ofthese samples (07-17-64-26W5 at 3800.6 m) has bitumen on 41 Charra 2: A..l!ID I~CLUSIONS IN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2·15: Stratigraphy of the Beaverhill Lake Group Swan Hills Simonette area Cafter Kaufman 1989). Figure 2·16: Stratigraphie succession of Simonette area (from Duggan. 1997). • 42 Figure 2-15 5 N • WOODBENO GROUP 1 -110 m ELK POINT GROUP Figure 2-16 SW NE AGE FORMATION ,,-- - 1000 - ~ ~ Paleocene and Maastrichtian seo Level -0 - SmoKyGp. - Cretaceous Dunvegon .... - -1000 Ft. st. John Gp. - --~ Bullhead ------Fernie ...... ---~ - - -- - _.--~----- Triassic Montnev .----- &:Mur Belloy tI'~.---- Rundle Group -- - -2000 CarbOniferous - Banff - - .... Wabamun - Winterbum Gp Devonien ,...... - WoodbendGp - - - -3000 Be.verhUi Lake Gp. ,..------Watt Mountain _ "- - x Cambrian x r]'C r ]'C )1( 1C r ]'C li' ,..'" ,..'Il" ,..'" ,..'" ,..'" ,..t" .,.,t:1' ,,1" '" ~x~<~<~<~<~<~~~~~~ r]'Cr "'r "'JI' 1Cr 1Cr 1C)I( 1Cr 1C.!:- PrecambriOn b< .,..1l:1' ",1" ,.. t Jo ... t" ,,. .. , x ... X • -lOkm C/rapta 2: RUfO lNCLUSIONS lN Lt.IE-STAGE CARBONATE CEMENTS - DEEP SUBSURfACE • Figure 2·17: Paragenetic sequence of diagenetic events for Swan Hills Simonette buildup. The intermediate burial realm is defined relative to low-amplitude stylolitization in limestones (500-1000 m: Dunnington. 1967: Lind. 1993). Deep burial is inferred to be >2500 m. A geothermal gradient of 25°C/km was assumed for Paleozoic time and 22 23°C/km during Tertiary time (from Duggan. 1997). • 43 • Figure 2·17: Paragenetic Sequence • Swan HUis Simonette MicrlTizotlon Il 1 Early Pyrite 1 •• 1 1 Physicel Compactfon 1 Early celcite 1 cements FC 1 Replacement 1 ., ., ., ., ., Dolomitizarion R1• R2/R3? R3 R5 1 1 Stylofites i Frocturing ., ., ., ., ., ., ., - 1 Twinned CalCite 1 ., ., 1 ., Cements 1 le IIC felLC Planer and Scddle Dolomite Cements ..Pp SD Vertical Stylotites 1 1 Oil present -1 ., ., 1 DissolutIon • 1\1_1 Anhydrite - 1 Pyrite. Spha/erite. 1 - galena ! 1 • 1 Pyrobitumen 1 ., 1 ... 4. Near Surface Maximum• Burial Realm Bunal Shallow --+ Intermediate • Deep Temperature ~ ··A~:: (OC) ~ / ~~ Major Orogeny AnUer ColumbianlLaramide 6QOm 1 2GOOm 1 to to 10QOm y 3000m Y Ouggon (1999) dNided R1. R:!. R3. and R5 • replacement cJoIomlte phases FC - Fatycalcite dMdes calCite and PD - Plana Dolomite IC -Infermedlate calcite dolomite pf'Joses into SO • SocJdle dolomite LC - Lote calCite • me tol/OWing CategorIes: Clrapur 2: FLUID lNCLUSIONS lN tATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE the surface of the saddle dolomite crystals. The other saddle dolomites did not fluoresce • under ultraviolet light and thus may lack hydrocarbons. or al least tluorescing ones. Fluid Inclusion Description The size of primary inclusions are larger in the calcites (5 x 7 to 12 x 18 JA,m) than in the saddle dolomites (2 x 2.5 to 5 x 5 Jlm). Primary inclusions within cements are 2 phase. liquid-vapour (L-V) fi lied. Their L-V ratios (F) are relatively consistent at F = 0.85 to 0.90. Inclusions lacking vapour bubbles are common and are interpreted to have fonned secondarily in a lower temperature environment (see Williams-Jones et al. (1987) Goldstein and Reynolds ( (994), references therein, and Appendix C). Homogenization Temperature (TaJ Data Late Calcites Homogenization temperatures were obtained for 40 inclusions in 3 calcite sarnples (Fig. 1-18a, Appendix A. Table A-2). Average homogenization temperatures in these samples are between 129.9 and 147.9°C (mean=140.4°C. n=40) (Fig. 2-(9), slightly hotter than those repol1ed from 3 late-stage calcites by Duggan (1997) (i.e.• average Th = 117.0 to 128.7°C. mean = 120°C, n=29). The samples analysed come from similar depths, and there is no apparent correlation between burlai depth and homogenization temperature (Fig. 2-20). When ploued versus estimated maximum burial depth (Fig. 2 20) samples plot near a 2üoC/km geothennal gradient. • CJU1p'~r 1: R..UID INCLUSIONS lN Lo\TE-STAGE CARBONATE CEMENTS - pEEP SUBSURFACE Saddle Dolomites • The two saddle dolomite samples studied are from the same weil (07-17), from depths of 3787.1 m and 3800.0 m. Th data are plotted in Figure 2-18b. The average homogenization temperature of primary inclusions for the twa samples is 148.2 and 154.3°C. respecti vely (Fig. 2-19; complete dataset is presented in Appendix A. Table A 2). These data are similar to what Duggan (1997) obtained for two saddle dolomite samples (average Th = 150.3 and 157.9°C). Although the dataset is relatively small (i.e.• 24 inclusions from 2 samples and 14 from Duggan's 2 saddle dolomites). there i5 a positive correlation (Le .• 0.86) between average homogenization temperature and burial depth. When estimated maximum burial is considered. the saddle dolomites plot near a geothermal gradient of about 23°C (Fig. 2-20). Applying a pressure correction (see Appendix C) to the Th data before plotting it against maximum bunal produces a c1uster of points around a gradient of approximately 24°C/km (Fig 2-20). Freezing Point Depression (Tm> Data Freezing point depression measurements for the three late-stage calcites (Fig. 2 ISe) give average salinities ranging from 22.2 to 23.6 weight % NaCI equivalent (Fig. 2 19: see Appendix A. Table A-2). The Mean is 22.7 weight % NaCI (n=32) which is slightly lower than the mean of 23.2 detennined for the 3 late.calcites studied by Duggan (1997). There is a positive correlation between salinity and buriaI depth (Fig. 2-21), with a relatively \Vide scatter at any one depth. There is no correlation between homogenization temperature and freezing point depression for Duggan's data (1999), but there is a correlation (0.82) between salinity and Tb data from the three calcite samples • studied in this work (Fig. 2-22). 45 C1U1/?Il'r 2: A.UID INCLUSIONS IN LATE-STAGE CARBûNATE CEMENTS - DEEP SLJBSlJRFACE • Figure 2-18a: Homogenization temperatures of late-stage calcite cements, Swan Hills Simonette reservoir (mean = 140.6°C. n=69 from 6 samples). Data are Iisted in Appendix A. Table A-2. Figure 2-18b: Frequency distribution of homogenization temperature data, late diagenetic dolomites. Swan Hills Simonette buildup (n=38, from 2 samples). Mean is 153.9°C versus mean of 154.6c C (n=14) for data from Duggan (1997). Figure 2·18c: Salinity data from late-stage calcite cements. Swan Hills Simonette reservoir (mean = 22.7 Wt. % Nael equivalent, n=46). Salinities are calculated from freezing point depression data following Bodnar (1992). Figure 2·18d: Frequency distribution for salinity measurements (see Appendix A, Table A-2) from two late-stage dolomite cements, Swan HUis Simonette buildup (n=16, from 2 samples). • 46 • F1tur. 2·".: T.. Data far S••n MIs SImone. La" C.ld. Cementa 0+--...... ----- cf' ....;> ..O? ...~ ~Q ... 0+------~ .....13 ...j) ...-fI ..' ...... 'ft ~ ~ -.:- .....<- .cl) Flture2·'ld: S....1tV D... _ Simonea. Saddla Datomlt8. ~J ~ ~ !" ... 2 0-...... ------__- _ ,"JI ...... 'b • ",'" CI/DRur 2: A.lJID lNClUSIONS lN LATE·STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2·19: Depths (m), average primary fluid inclusion homogenization temperatures (oC). and average salinities (Wt. % Nael equivalent) of late-stage calcites and saddle dolomites. Swan Hills Simonette. Data are listed in Appendix. A, Table A-2. Figure 2-20: Average homogenization temperatures of late-stage calcite and saddle dolomite cements from Swan Hills Simonette plotted versus present and calculated maximum bunal depth. The raw Th data is plotted twice: versus present sample depth and calculated maximum bunal. 2000m of Uppermost Cretaceous and Tertiary strata were eroded from this area (see text). A third set of data points represents the pressure corrected Th data (assuming a H20-NaCI fluid). The pressure corrected calcite data from this study plot in a wide scatter between 20°C/km and 24°C/km geothermal gradients (l5°e surface temperature), while those data for saddle dolomites plot between 24°C/km and 26°C/km. See Appendix. C for discussion on pressure correction. Three calcites (hollow circles) and two saddle dolomites (hollow diamonds) are included from Duggan (1999). The small inset graph illustrates the correlation between Th and Tm among the saddle dolomites at Simonette. • 47 Figure 2-19:Averag. T" and T", - Simonette Sampi•• Range 1 (6th) Range 27 (5th) Range 26 (West of the 5th Mendian) • • o (Karr field) • LEGEND: • Vertical Wells o Oeviated Wells c:JLimit of Reservoir SCALE 1:100 000 o km 10 After Duggan (1997) Figure 2·20: T" vs. Pre..nt and Calçulated Maximum Burial Depth for Lat...tage Cem.nts (Simone...) 8500 ~------"":::I----- ~ 7500 j î 6500 l T."..~ muimum tIuri* 1.5001 ("gw 'rrntaot.) CD 1 1 4500 :r~--l ~~.. -- -.- ----.- --- . 1 3500 • 100 110 120 130 140 150 160 170 180 190 200 • Hamogeniution Tempe,..... (Til in ·C) Charra~: FLUIO INCLUSIONS IN LATE-STAGE CARBONATE CE~ENTS- DEEP SUBSURFACE • Figure 2·21: Present bunal depth versus salinity, Swan Hills Simonette late-stage calcite (n=46 from 5 samples, including data from Duggan, 1997 - see Appendix A, Table A-2) and dolomite cements (n=16 from 2 samples). Open circles represent data from Duggan (1997). Figure 2·22: Swan Hills Simonette buildup late-stage calcite and saddle dolomite cements. average homogenization temperature (Th) versus freezing point depression (Tm). The plot suggests that salinity increases with increasing Th. Open circles represent data from Duggan (1997). • 48 • Figure 2-21: Freezing Point Depression vs. Surlal Depth, Swan Hilis Simonette 3700 1 [ 3750 1 • Calcites 1 • Saddle Dolomites o Duggan (1999) Ê 3800 • ... •• l ~ 1 1 Q. •• 4l- .v~... G 1 1 Q 1 r·.. ii 1 ï: 3850 1 ~ 1 CD 1 i 1 C 1 -l- -G 1 1 1ft 3900 0 1 ! OOCDoà 0 1 ~ 1 ! 1 i 1 3950 1 1 1 1 1 ~ooo 1 ·14 ·15 ·16 -17 -18 -19 -20 -21 -22 -23 -24 Freezlng Point Dpre.slon (T", • oC) Figure 2-22: Th vs. Tm for Swan Hill. SimonaUa Sampla. -14 ..-----~------_-- --_-_.. ·15 o _ Late ~ldtes 1 • s.c!dle OakJmil8s p" ·'6 . •• 1OOuggan (1999) ...E -'7 • • C o • • • ";i "8 • 1ft -. li» • • • ..•• ! "9 • • ••• c '0- -20 ·S -•. • ~ e. ,- ~ - C -21 i ! ~ ·22 o o ..".•..-:. o~ .- .24 J-..-- ~ 90 100 110 120 130 140 150 160 170 180 19o 200 210 • Homogenlzatlon TemperatuN fT" •·C) CJUlDll!r 2: FLUID INCLUSIONS IN LATE-STAGE CARBONATE CEMENTS - pEEP SUBSURFACE Salinity data for saddle dolomites are presented in Figure 2-18d. The average salinities • for the two late-stage saddle dolomites are 20.2 and 21.5 weight % Nael equivalent (Fig. 2-19). Similar to the calcites, there is a positive correlation between salinity and burial depth (Fig. 2-21) with a wide scatter of salinities at any one depth and no apparent correlation between Th and Tm (Fig. 2-22). Isotopie Evidenee Duggan (1997) reported that late calcites within the Swan Hills Simonette buildup are strongly radiogenic (87Sr/86Sr =0.7288 to 0.7369). The saddle dolomites studied are moderately to strongly radiogenic (~7Sr/86Sr =0.7118 to 0.7370). The 87Sr/86Sr values l'rom late-stage carbonate cements are even higher than those documented by Machel et al. (1996. 1999) for Obed. and are the most radiogenic-rich carbonate cements found in deep basin Devonian rocks to date. The Sr isotope signatures associated with the late-stage carbonate cements of the Swan HUis Simonette show no correlation with increasing bunal depth (Fig. 2-23). \Vhen 87Sr/86Sr is plotted versus township. no convincing trend is evident (Fig. 2-24a); however. as at Obed. a westward increasing trend in IHSr/86Sr is apparent on a local scale amongst the saddle dolomites when Sr isotopes are ploued versus Range (Fig. 2-24b). Duggan et al. (2001. in press) report that the highest 87Sr/86Sr saddle dolomites are situated near sub-vertical faults that have been traced, using three dimensional seismic data. down through to the base of the Devonian (Duggan. 1997). Similar to Qbed samples. late-calcites with high 87Sr/86Sr generally have lighter 5180 signatures (Fig. 2 25a). This generai trend is evident amongst Simonette saddle dolomites, although the • scatter of the data points is greater than il is for late-diagenetic calcites, and thus no TSR 49 C/UlDft'r 2: RUm iNCLUSIONS lN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2-23: 87Sr ratios plotted versus present day bunal depth of late-stage carbonate cements. Swan Hills Simonette area. Data (0=18) are from Duggan (1997). Figure 2-24a: 87Sr/86Sr versus Township. late-stage carbonate cements Devonian Swan Hi Ils Si monette. Data are from Duggan (1997). 6 Figure 2-24b: 87Srl Sr versus Range, late-stage carbonate cements Devonian Swan HiUs • Simonelte. Data are from Duggan (1997). 50 86 Figure 23: 87Sr/ Sr vs. Present Burial Depth • 3500 3700 e • ••• ~ 3900 • • • •• cg •• .... Q ti i 4100 • • c: -CI) en ~ 4300 4500 0.710 0.715 0.720 0.725 0.730 0.735 0.740 • Late-calcite • Saddle dolomite North 1 Figure 2-24a i i 1 1 ! 1 ! L 1 1 i 1 l ! ; 1 a le.. a 1 le 1 al a.: ! 1 ~ ca 1 1 • w :c i a i Ut c 1 1 1 1 C 1 aV 1 1 1 1 1 1 1 1 1 1 1 a' 1 ! 1 1 ~! ! 1 1 1 1 1 'il 1 1 .... 1 1 1 ! • 1 1 i ! 1 1 South 1 1 1 l 1 J ft ft West Figure 2-24b: Ilia 1 1 .~ 6~ Meïdian ~" ~ "l""""" r""""" ... r""""" i"·" N CDt a ~i' 1 Jr.le la 'II a 8 1 • a::~«1." e • ~ , 1 a f 1 al - ,it 1 ! 1 1 1 1 • East 0.715 0.720 .0725 0.730 0.735 0.740 •Sr" ~r Cllapll!r:!: FLUID INCLUSIONS IN LATE·STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2-25a: 87Sr/86Sr versus 8180 for Devonian late-stage carbonate cements, Swan Hills Simonelle (after Duggan, (997). Figure 2-25b: Sl3e versus SI80 for Devoniun lute-stuge carbonate cements, Swun Hills Simonette. Data are from Duggun (1997). • 51 • Figure 2·25a: a7Sr"'Sr vs. 0"0 • Swan Hills Simonette 0.7380 r------...., 1 ! ,-.. 0.7330 1 1 • • Late Calcites • • Saddle Dolomites 1 - 0.7280 i 1 • .- ~ 1 en 1 • \: 0.7230 1 • ~ : • • 0.7180 • • • 0.7130 •• 0.7080 ...... ---_----_---_----_----i -20 -16 -12 ·8 4 o & 1·0 (%e, POS) Figure 2·25b: o13e vs. 0"0 • Swan HUIs Simonette 5 # • • • • ..••,• •.•... • o •,f'.lit • SUc ('Y.. PDS~ 1 1 -5 1 1 1 1 ! • -16 4 o Clu'Ptt'r 2: FLUID INCLUSIONS lN LATE-STAGE CARBONATE CEMENTS - DEEP SURSURFACE reactions appear to have taken place. Both late calcites and saddle dolomites have heavy • o13e signatures relative to Obed (-0.92 to 3.76). Saddle dolomites yielded a wider range of 0 180 than the calcites (i.e.-6.66 to -12.61 versus -9.6 to -12.77. see Fig. 2-25b). Burial History There are two main ways to estimate burial history. a) back-stripping using the regional stratigraphie succession, and b) using the thermal maturation of organic matter. The thickness of Upper Cretaceous strata near the defonned margin is up to 5500 feet or 1675 m (\Villiams and Burke. 1964). The thickness of Upper Cretaceous ~trata at Obed was likely similar before later Tertiary erosion. At the time of the Cretaceous Tertiary boundary (-63.4 Ma) sediment input into the basin decreased substantially (Mossop and Shetsen. 1994). This non-deposition coincided with a short period of tectonic quiescence in the mountains to the west, and was followed by another influx of non-marine c1astic sediments in the Paleocene. Presently, Tertiary strata only exist near the defonned belt. The isopach map of the eroded Paleocene cover across the deep basin (Taylor et al.. 1964) suggests that a minimum of 1000 m of Paleocene strata covered the Obed area. Before erosion, the Early Teniary could have been close to 1500 to 2000 m thick. Therefore, burial reconstruction suggests that Devonian strata at Obed were overlain by at least an additional 2675 m (1000 + 1675) of strata that were subsequently removed during Tertiary erosion. Nurkowski (1984) and Majorowicz et al. (1990) used coalification measurements to estimate the thickness ofTertiary and Upper Cretaceous strata removed from the basin~ but the Obed area was not included in these studies. Of the few published estimates • conceming the thickness of removed Upper Cretaceous and Tertiary strala in the basin, 52 Cllllpta 2: ELUID INCLUSIONS IS LATE·STAGE CARBONATE CEMENTS - OEEP SUBSURFACE • Figures 2·26a & b: Map of thickness of strata estimated to have been eroded (metres) from the Alhena Basin. A. from Hitchon (1984), is based on the relation between coal rank and maximum paleotemperature to calculate the paleogeothermal gradient at the time of max.imum bunal. Estimated thicknesses of eroded strata were determined by dividing paleotemperature by paleogeothermal gradient and then subtracting present depth of bunal for near surface coals. B, from Bustin (1991), is also based on Cretaceous coal data. Amount of strata eroded reaches a maximum of between 3000 and 3800 m along the edge of the foothills. • S3 • • .. ------Rgure-2-26b: --~~flgure-2:~6a: II~ -..!~~r Il 6Il'N..--I2tJW ,..1111' .,__''l'> __..2 r14 -r__ 1, l , ~ L60"N 1 1 l' 1, o 100 :ZOO ~KJ ~,""".I' •• t " 1 1 1 '' ,1 lCJO XlO "".... ' 1 i, 1 -1" ,1 -~' 1 , 1 1 I~ , 0'1 '0t~ 1, .- 1 • ;00::- 1, .DI '..... le. , El ...... '0 ALBERTA Rt4'" , ~ ~'i:J J , :JI B Il , -0 '"...... ,),~ 1I:E(1) ./ ; , ~IU, '0I~ 1, Ci) , , (._....'.ldl =i=: , 1 SIUON~l1E ~I'55"" 'i:, , , co, 1 , 1 / J~ , M'r, ....,'..'" 1M ,. 'M"" s.... HI'" 1, ~ ~p 1 , ' 1 , '","') ~ 1 _, !ll'N ~ ~ , ", 1 , ü~ 1 '''~- -hr J,52'" 52'\- 1 , ", 1 , '\ , , -\ 51'N ".~... 1 , o IO(HIIl \ '0 BRITISH l ' , o 60 ml COLUMBIA \'" 1~ II 5(T~, =::.'J-t!lO' c.• ., , JoI'I'N 49'N \L----- 117 '" 114' - __- 'IO'W C1Umrt'f' 1: R...lJlD INCLUSIONS lN LATE-STAGE CARBONATE CEMENTS - DEEP SUBSLJRFACE those of Hitchon (1984) and Dustin (1991) are most relevant (Figs. 2-26a and b• • respectively). Hitchon (1984) used the relation between coal rank and maximum paleotemperature to calculate the paleogeothermal gradient across Albena at the time of maxi mum bunaI. Estimated thicknesses of eroded strata were detennined by di viding paleotemperature by paleogeothennal gradient and then subtracting present depth of burial for near surface coals. According to the contour map created by this mcthod the Obed buildup lies between the 2750 m and 3000 m contours of strata removed (Fig. 2 26a). Bustin (1991) produced a thickness map (Fig. 2-26b) by extrapolating measured matunty gradients and surface maturity values. While the overall pattern of contours appears very different. Bustin's (1991) map shows the approximate thickness of strata eroded at Obed to he between 2500 and 3000 m. similar to the estimate of Hitchon (198..J). Both studies (i.e.. Hitchon, 1984 and Bustin, 1991) support the 2700 m estimated by stratigraphie back-stripping and extrapolation. Thus, at maximum burlal, the Devonian strata at Qbed would have been buried approximately 2700 m more deeply than at present. Maximum formation temperatures are estimated to have been between 155 and 225°C (assuming 20 and 30°C/km geothennal gradients. respectively. and a surface temperature of 15°C) (Walls el al., 1979; ~tattes and Mountjoy, 1980). These estimates combined with fonnation thickness data from wells in the study area (Table 2-1) were used to construct a burial history for Devonian stmta at Obed (Fig. 2-27a). Maximum buria! for the strata occurred during the Paleocene in the deep basin but probably earlier in the Foothills and Front Ranges. • The isotherms (Fig. 2-27a) were calculated using a geothennal gradient of 54 Clrapca~: FUJID INCLUSIONS IN U,TE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE • Figure 2·27a: Reconstruction of burial history of Qbed reef complex for base of \Vabamun. Erosion during the Tertiary is estimated to have removed a minimum of 2700 m of sediments in this part of the basin (see text). Temperatures are based on a surface temperature of 15 Oc and a geothermal gradient of 25 °C/km (see text). Formation thickness is based on the weil data presented in Table 2-1. Figure 2·27b: Burial history of Swan Hills Simonette reservoir. Reconstruction includes 2550 m of erosion during the Teniary (Hitchon. (984) and uses decompaction parameters for shale. sandstone. and Iimestone for Cambrian to Cretaceous strata (Baldwin, 1971; Dickinson, 1953; Sclater & Christie, 1980; Schmoker & Halley, 1982). Sedimentation and erosion rates are calculated using decompacted thicknesses. Modified from Duggan (1997). • 55 o • TERTIARY 1000 2000 3000 -E --~ - ~-' t 4000 I-_-4050--.. m ~ C -4650m •__-_Ooolel.. o..t_, ca"t: 5000 ~ -- m 6000 350 300 250 200 150 100 50 o 0 0 iOOO 1000 2000 2000 3000 Base Beaverhill Lake Group 3000 E ~ ~ Top Precambrian a .. 0rganK:. .. .- eu Man. 3900m C 4000 4000 ...... ,."-' 8..,... o.pth - --- 'D~ e..w.o- Onset of Hydnx:artlCln Cradung & T. s. R " 5000 " 5000 i - -HIATUS- --J_ 6000 " 6000 7000 7000 500 400 300 200 100 0 • Age (Ma.) C/rapcu 2: FLUID INCLUSIONS IN Lo\TE-STAGE CARBONATE CEMENTS - DEEP SUBSURFACE 25°C/km. Considering the work of Walls el al. (1979), Mattes and Mountjoy (1980), and • Hitchon (1984) who estimated paleogeothennal gradients for different areas of the basin, 25°C/km appears to represent a reasonable estimate of the average geothennal gradient for the eastern Alberta Plains from the Devonian to Early Teniary. Duggan (1997) calculated that the Devonian strata at Simonette were buried 2500 m deeper than at present (Duggan, 1997)~ therefore, maximum burial for Devonian strata is estimated to have been about 6500 m (Fig. 2-27b). This study follows Duggan's estimate. Techniques based on organic maturity estimate a thickness of removed overburden for this part of the deep basin ranging between 1400 (Margara, 1976) and 2550 m (Hitchon. 1984). UnfoI1unately Bustin's (1991) estimates do not include the Swan Hills area (Fig. 2-26b) but suggest something between 2000 and 3000 metres. • 56 A FRACTURED AND BRECCIATED. • PARTIALLY DOLOMITIZED HOST L1MESTONE '. LATE-STAGE . Ao" FRACTURE-FILLING CALCITE B DOLOMITIZED HOST ROCK LATE-STAGE, VUG-FILLING DOLOMITE LATE-STAGE. VUG-FILLING CALCITE LATE-STAGE CALCITE STYLOLITE (containing bitumen) _- HOST LIMESTONE Plate 1: A) Late-stage calcite Obed buildup (7-18-52·24W5, 4823.3 m) filling fractures in brecciated partially dolomitized limestone. The field ofview is 17 mm. D) Vug-filling late diagenetic cements Obed buildup (14-23-53-23W5, 4126.lm). The late calcite cement postdates the dolomite phase (white) which lines the walls ofthe vug. The field ofview is 10 mm. C) Obed late-stage calcite cements filling a vug associated with stylolite that contains bitumen(7-15-52·22\V5,4186.3 ml. Thefieldofviewis 10 mm. • 57 • TWlNNING PLANE B CORRODED DOLOMITE CRYSTAL EDGE LATE·5TAGE CALCITE LATE-STAGE SADDLE DOLOMITE BITUMEN c TYPICAL PRIMARY FLUIO INCLUSIONS Plaie 2: A) Twinning is commonly observed in Obed late·stage calcite cements. The field of view in the photo is 17 mm. (Weil 9-23-54-23 W5. 3977.4 ml. B) Late·stage calcite postdates late-diagenetic saddle dolomite phases. Occasionally corroded saddle dolomite crystals line wallsofvugs. Thefieldofview is 17mm.(WellI4-23-53-23W5,4126.1 m).C}Primaryfluid inclusions in late-stage calcite cement have constant Iiquid-vapour ratios of about 0.9. The field ofview is 2.5 mm. (WeIl9·23-54-23W5. 3977.4 ml. • 58 • A ~~ftI:~_ LATE-STAGE CALCITE FILLING MOLDIC POROSITY B PRESSURE SOLUTION HORIZON BOARDERING VUG VUG-FILLING LATE-STAGE CALCITE c Plate3: A) Coarse-grainecllate calcite cement filling moldic porosity previously occupied by calcite fossil (weil 07-17-64-26W5. 3800.6 ml. The field of view is 17 mm. D) late-stage calcite filling vuggy porosity nearstylolite (weil 07-17-64-26W5. 3800.6 ml. The field ofview is 13 mm. C) Saddle dolomite fillinga vug(wel1 07-17-64-26W5. 3787.1 ml. The fieldofview • is200~m. 59 CHAPTER3 • DEVONIAN OUTCROPS Of THE ROCKY MOUNTAINS; FLUID INCLUSION AND ISOTOPE DATA The Devonian strata now exposed in the Front Ranges of the Rocky Mountains formed the southwestern extension of the Alberta basin. As a result these rocks shared a bunal. and probably a diagenetic, history similar to that of other Devonian buildups in the basin until thrusting and uplift. Presently. few tluid inclusion data have been published for Iate-stage cements in Devonian outcrops of the Rocky Mountains. Homogenization temperature. salinity. and isotope data for outcrop samples are presented in this chapter. following a brief outline of the stratigraphy of the Front and Main Ranges. A discussion of the burial history concludes this chapter. The diagenesis and f1uid inclusion data of these sampIes are compared to subsurface samples in Chapter 4. Stratigraphy Correlations between Rocky Mountain surface and Albena Basin subsurface Middle and Upper Devonian formations are summarized in Figure 3-1. Wabamun strata are equivaIent to the Palliser Formation, which outcrops in the Front Ranges. Ali sampIes were collected from the Palliser Formation except: late-stage calcites from Toma Creek. and late-diagenetic carbonate phases at the Big Hill Section, from the Frasnian lower Peeehee / Upper Cairn formations; and samples at Mannot Cirque and Riee Brook • from the Cairn Formation. Charter 3: DEVONfAN OUTCROPS OFTIiE ROCKY MOUNTAINS; RUfD INCLUSION AND ISOTOPE DATA • Figure 3·1: Stratigraphie Table Late Devonian strata west·central Alberta Basin and outerops in Front and Main Ranges of the Rocky Mountains (from Shields and Geldsetzer. 1992). • 61 • • Figure 3-1: UPPER DEVONIAN CORRELATION CHART WEST-CENTRALALBERTA SURFACE OUTCROP 1 SUBSURFACE AGE CARBONATE fACIES lITHOLOGY CLA5TIC FACIES • CARBONATE FACIES lllHOlOGY CLASTIC FACIES CARBONIF. z < Z ~ PALLISER WABAMUN LATE ~ ~ z ~ Z m...... ~~L&.IolIo.l.W .....~-...a_.. MT. HAWK ~ NISKU o ~ ammn.Dmall;!:1~ > wQ w z ~UJ < ..J c Z ~L-"""--J:;:~~- 0 IRETON - U) ~ z LEDUC ~ :< PERDRIX ~ - u. ~z 0 a:: 0 DUVERNAY - ~- 0~""------I MAJEAU LAKE COOKING LAKE FlUMEM. • ~-] ...... -~....,.. FlUME MIDDLE 1 GNET-lIIll1lt~.. mrrmITITI ~~~~~~ Ouvrer 3: DEVONIAN OUTCROPS OF THE ROCKY MOUNTAINS; FLUiD INCLUSION AND ISOTOPE DATA Paragenesis • A general paragenetic sequence for Front and Main Range Devonian outcrops (Fig. 3-2) is based on the work of Mattes and Mountjoy (1980), Melim et al. (2000). and observations from this study. The calcite and dolomite cements studied formed late in the burial history (Section 3.6) of the Devonian buildups. Hall' of the cements studied from outcrop (i.e., 8 of 16) are from fractures. Syn and post-thrusting fractures cross cut ail other components of the paragenetic sequence (Fig 3-2), and post-thrusting fractures cross-eut the synthrusting generation (at Disaster Point and Cirrus Mountain). While calcite and dolomite phases filling the synthrusting fractures fonned in a deep burial environment. coarse blocky calcite filling post-thrusting fractures fonned weil after maximum burial was reached in the Paleocene (see Section 3.6). The bedding parallel. synthrusting fractures are best evidenced at Disaster Point. whcre slickensides occur along them and are weil exposed (Mountjoy, 1960: Plate 238). Three vug-filling late calcites. not apparently associated with fractures, were also sampled (at Spray Lakes. Parker's Ridge. and Big Hill). [n addition five late phases (three calcites. a saddle and a planar dolomite) from brecciated Devonian reefal facies (at Marmot Cirque and Rice Brook) were tested for 87Sr/86Sr. Ô180, and ÔI3C. These phases and the vug-tïlling calcite cements postdate stylolitization and are petrographieally similar to late phases filling synthrusting fractures. FRONT RANGES F1uid inclusion and isotopie data were colleeted from seven samples from five localities where Frasnian and Fammenian strata are exposed in the Front Ranges (Fig. 1 • 3). Four of the five calcite cement samples studied are medium to very eoarsely- 62 ChanleT 3: DEVONIAN OUTCROPS OF THE ROCKY MOUNTAINS- FLUID INCLUSION AND ISOTOPE DATA • Figure 3-2: General paragenetic sequence for Devonian outcrops, Front and Main Ranges. Based mainly on Mattes and Mountjoy (1980). • 63 • Figure 3·2: PARAGENETIC SEQUENCE (Front & Main Rang••) Meteoric .Marine Burial Dee Buriat U 11ft Micritic cements 1 2 lsopachous cements 1 1 _ 3 Calcian dolomite 1 1 4 Subaerialexposure 1 5 Dissolution 6 Fine blocky calcite 7 Neomorphism 8 Micrite- microspar 9 Stylolitization (whispy) 10 Replacement Dolomites 11 Silicification 12 Mechanical Compaction 13 Stylolitization 14 TSR 15 Deep Burial Vug-filling CC 16 Syntectonic Fracturing •••• 17 Late Dolomite Cements 18 Late Calcite Cements Post-tectonic Fracturing - 19 .,.. 20 Coarse blocky calcite - 1111 (in post-tectoOlC fractures) 1 SEA SHALLOW NTERMEDtATE DEEP FlOOR BURIAL BURIAL BURIAl N.B. - 50 =saj(jle dolomite. PO :: plan... dolormte 600 2000 to to 1000m 3000m • • • T.ble 3-1: Summary of Dai. for Devonlan Outcrop samples. FRONT RANGES MAIN RANGES ~OCIIlton: OISASTER POINT COlD 5. SPAtNG TOMA SPRAYlAKES ..ARMOT CIRQUE PARKER'S BIG HlU CIRRUS ..TN. fleE BROOK CREU RIDGE ~I For".Uon; ...... P..... f·..... t·lUCtw. f·••••' P..... Av... 'Il ('Ct: 106 7 191.1 182 7 1685 1634 1455 1930 lJ96 1339 17J2 104.1 fi) le) f14/ flO) III) 122) Ill) fil) (1111 C13) fl31 fl O) Av... T.('Ct: ·53 ·142 ·136 -IJ5 ·104 -IJl ·150 -164 ·159 ·132 .fi 7 ."'fUCl': 82 180 174 173 14J 169 186 19.7 194 170 101 fi) (&1 flll (1) (II 1211 Ctl (91 (101 f71 (Il f~/ it'1ItJl'Sr: 0.70866 0.70918 071277 071283 070918 070860 070940 071125 071057 071058 070926 0.71009 070650 070938 0.70961 0.70939 ~ "0l"o.roe): ·1834 .fi 64 -7.59 .fi 53 -900 ·1082 ·1027 ·11 67 ·818 ·1120 ·1131 ·965 -820 ·1760 ·921 ·IU9 ~ "e l'L. POBI: .055 .0.38 -2.06 ·140 ·1500 -12.31 ·1309 ·11 35 .J 76 ·2J64 ·1132 -IJl .0 18 -032 ·1019 ·7.38 1 • (i ., equivalenll ChaUler 3: DEVONIAN OUTCROPS OF THE ROCKY MOUNTAINSj FLUID INCLUSION AND ISDmPE DATA crystalline. late-stage phases that fill tectonic fractures that are sub-parallel to bedding. • The tifth is coarsely-crystalline, blocky fracture-filling calcite that likely formed in a post-thrusting tensional environment. A coarse to very coarsely-crystalline, saddle dolomite filling a tectonic fracture. and a medium to coarsely-erystalline. late dolomite cement filling a stromatoporoid. were also subjected to fluid inclusion and isotopie study. Based on observations canied out in the field and in the laboratory. this study argues that fractures that are sub-parallel to bedding are related to thrusting and (hose that are sub vertical are post-thrusting. A calcite and a saddle dolomite from a brecciated zone at the southeast Miette reef margin in Marmot Cirque were also tested for 87Srl~6Sr, ôt80. and ô13C. Data from outcrop samples are summarized in Table 3-1. Disaster Point Two generations of fracture-filling calcites were sampled at Disaster Point (Fig. 1-3) from the Palliser Formation. The aider, tectonic generation of fractures hast coarse, equant calcite cements (SM-53, Plate 4a) and occur in 5-15 cm wide veins that sub parallel bedding. Primary inclusions within this cement have consistently small vapor bubbles with a fluidlvapor (F) ratio of 0.9. The average Th for the primary fluid inclusion assemblage (FIA) examined is 191.1°C (Fig. 3-3a). The fluids in these inclusions. have an average 18.0 wt% Nael equivalent (Fig. 3-3b). are somewhat less saline than those found in the subsurface late-calcites at Qbed (19.7) and Simonette (22.7). A plot of Th versus Tm illustrates a very weak positive correlation (i.e., 0.4) between formation fluid temperature and salinity (see Fig. 3-4). • The first fracture system is cross-cut by fractures that are perpendicular to 64 Chapter 3: DEVONIAN OIJTCROPS OrTHE ROCKY MOUNTAINS- flUlD INCLUSION AND ISOTOPE DATA • Figure 3-3a: Frequency distribution of homogenization temperature (Th) data (Appendix A. Table A-4) for late-diagenetic syn-tectonic fracture-filling calcite cement (SM-53). Pal liser Fonnation. Disaster Point. Miette Range. Highway 16. Figure 3·3b: Frequency distribution of salinity measurements (Appendix A. Table A-3) from late-stage syn-tectonic fracture-filling calcite cement (SM-53). Salinities are calculated l'rom freezing point depression (Tm) data following Bodnar (1992). Figure 3·.k: Frequency distribution of homogenization temperature data (Appendix A. Table A-4) for late-diagenetic post-tectonic, fracture-filling calcite cement (SM-50). Palliser Formation. Disaster Point. Figure 3-3d: Frequency distribution of salinity measurements (Appendix A. Table A-3) from late-stage post-tectonic fracture-filling calcite cement (SM-50). • 65 • 0ï ...... 0 ~_T_rcl :1 • OupIa 3: DEVONlAS OUTCROPS OF THE ROCKY MOUNTAINS' FLUIO INCLUSION AND ISOTOPE DATA • Figure 3·...: Homogenization temperature plotted versus freezing point depression for late-stage carbonate cements from four widely spaced Front Range locations (Disaster Point. Cold Sulphur Spring. Toma Creek. and Spray Lakes) (n=67. from 5 calcite. 1 late dolomite and 1 saddle dolomite cement samples). • 66 • • Figure 3-4: Th YS. Tm for Front Range Samples -4 •• -6 -. Û ·é -8 t:. 0 ~ -10 ~- 0 - 0 o 0c:P wcP 8 ~oo 1) 0 0 'iIl f -12 Do ~ 0 6 • • . ( 0 ••.... 1 • c!: -14 r- ... •• ë -Ir-Zl ••-A A6 A "0 A 1 • Ae CL -16 Dtc A 1t -18 ! 1&. -20 1 -22 1 1 J 100 110 120 130 140 150 160 170 180 190 200 210 220 Homogenlzatlon Temperature CTh. ·C) • SM50: le - Disaster pt. • SM53: LC - Oisaster pt. • SMS4: LC - Cold S. Spring • 5M54: 50 - Cold 5. 5prlng o MM5: lC - Toma Creek o SM77: lC - Spray Lakes A SM77: LO - Spray Lakes Chapter 3: DEVONtAS OUTCROPS OFTHE ROCKY MOUNTAINS: A..UID INCLUSION AND tSOroPE DATA • Figure 3-Sa: Frequency distribution of homogenization temperature data (Appendix A~ Table A-3) for late-diagenetic calcite cements (SM-54C)~ Palliser Formation, CoId Sulphur Spring, Highway 16. Figure 3-Sb: Frequency distribution of salinity measurements (Appendix A, Table A-3) from late-stage calcite cements (SM-54C). Figure 3-Sc: Frequency distribution of homogenization temperature data (Appendix A, Table A-3) for saddle dolomite cements (SM-54D)~ Palliser Fonnation, Cold Sulphur Spring. Figure 3-Sd: Frequency distribution of salinity measurements (Appendix A, Table A-3) • from saddle dolomite cements (SM-54D). 67 Chapler 3: DEVONIAN OUTCROPS OF THE ROCKY MOUNTAINS· FLUID lNCLUSION AND ISOTOPE DATA bedding, and appear to post-date thrusting. Auid inclusions within the coarsely • crystalline blocky calcite from these later veins (SM-50) have substantially lower Th (average =l06.7°C; Fig. 3-3c) and salinity (8.3 wt% NaCI; Fig. 3-3d). Cold Sulphur Spring Coarsely-crystalline late-stage calcite and saddle dolomite phases were sampled from veins dipping sub-parallel to local bedding (i.e.. synthrusting) in the Palliser Formation at Cold Sulphur Spring. The coarse blocky calcite postdates the baroque dolomite cement that lines the walls of the fractures (Plate 4 band c). Inclusions within the calcite and dolomite cements have consistent tluid/vapor ratios of between 0.85 and 0.9. The average Th for the calcite's primary RA is 182.7°C (Fig. 3-5a), and the average salinity is 17.4 wt% NaCI (Fig. 3-5b). There is a weak positive correlation between homogenization temperature and salinity (Fig. 3-4). The clear, white saddle dolomite cement has an average homogenization temperature of 168.5°C (Fig. 3-5c) and an average salinity of 17.3 Wl. % NaCI (Fig. 3-5d). l8 I3 81Sr/86Sr of the calcite is 0.71277, Ô 0 =-7.59%c (PDB), and il has a Ô C value I8 13 of -2.06Ckc (PDB). The dolomite cement has 87Sr/86Sr of 0.71283, Ô 0 =-6.53, and ô C of -1.40. The 87Sr/86Sr values of calcite and dolomite phases from Cold Sulphur Spring \Vere the most elevated of aIl Front and Main Range samples analysed; yet their 87Sr/86Sr are only marginally above the Maximum Sr Isotope Ratio of Basinal Shales (MASRmAS =0.7120) as defined by Machel and Cavell (1999). TomaCreek A single, medium to coarsely-crystalline late-stage calcite from an inferred • fracture setting (Cavell, personal communication) in the Peechee Formation at Toma 68 Chapter J: DEVONIAN OUTCROPS OFTIiE ROCKY MOUNTAINS- RUfO INCLUSION AND ISOTOPE DATA Creek was analysed (Fïgs. 3-6a and b). Inclusions within the calcite have tluid/vapor • ratios of between O.S and 0.9. The average Th for the primary RA studied within the calcite is 163.4°C while its average salinity is 14.3 wt% NaC!. Homogenization temperature and salinity do not appear to cOlTelate for this sample (Fig. 3-4). The lack of correlation between Th and Tm and the variability of vapour bubble size in the sample (i.e.. 10 to 20%) suggest that the inclusions in this calcite underwent sorne degree of re equilibration during uplift and erosion. Spray Lakes Coarsely-crystalline. late-stage calcite and dolomite phases were sampled from the Palliser Formation in the Rundle thrust sheet north of the Spray Lakes Reservoir. The calcite fills vugs while the dolomite cement is found lining synthrusting fractures. Inclusions within the calcite and dolomite cements have relatively consistent tluid/vapor ratios of between 0.S5 and 0.9. The average Th for the primary RA of the calcite is 145.5°C and average salinity is 17.0 wt% NaCl (Fig. 3-7a and b). The dolomite cement yielded the highest average homogenization temperature among outcrop and subsurface cement samples (l93.0°C), and an average salinity of IS.6 wt% NaCl (Fig. 3.7c and d). The correlation between homogenization temperature and salinity is negligible for bath cements (Fig. 3-4). 1\'larmot Cirque A fracture within brecciated Cairn dolostone from the southeast margin of the ~liette reef complex at Mannot Cirque (M22; Mattes and Mountjoy, 1980) provided a late-stage calcite and dolomite cement sample. The fracture is lined with an isopachous • fringe of clear, bladed dolomite cement, and filled with medium to very coarsely- 69 Ctul"ter 3: DEVONIAN OUTCROPS OFnlE ROCKY MOUNTAINS- A.urD INCLUSION AND ISOTOPE DATA • Figure 3·6a: Frequency distribution of homogenization temperature data (see Appendix A. Table A-3) for late-diagenetic calcite cement (MM5) from the Toma Creek outcrop at Mackenzie NW Margin of the Southesk Cairn Reef Complex. in the McConnnell thrust sheet. Rocky Mountains. Figure 3·6b: Frequency distribution of salinity measurements (see Appendix A. Table A 3) from late-stage calcite cement (MM5). • 70 • Figure 3~a: Fr.quency Distribution of T .. Data for Toma Creek La. Calcite '1 61 ~ ~ :1r t 1 ~ 3 i 2 t 1 0 ~ ..iF ...,~ ...~ ..."'.Jt:;) ...~~ ...~ ..rSJ ...'\~ ..~~ HomDgenR.aIGn Ten.-rah.lre rel Figure 3-6b: Frequency Distribution of Salinity Data for Toma Cr.ek Lata Calcite 10 ------, J J :1 :t • Chapler 3: DEVONIAN OlrrcROPS OFTI-IE ROCKY MOU~TAINSjFLUIO INCLUSION AND ISOTOPE DATA • Figure 3-7a: Frequency distribution of homogenization temperature data (see Appendix A. Table A-3) for late-diagenetic calcite cement (SM-77) From outcrop at Spray Lakes in the Rundle thrust sheet near Canmore. Front Ranges. Figure 3-7b: Frequency distribution of salinity measurements (see Appendix A. Table A 3) from late-stage calcite cement (SM-77). Figure 3-7c: Frequency distribution of homogenization temperature data (see Appendix A. Table A-3) for late-diagenetic dolomite cement (SM-78) From outcrop at Spray Lakes the Rundle thrust sheet near Canmore. Front Ranges. Figure 3-7d: Frequency distribution of salinity measurements (see Appendix A. Table A 3) From late-stage dolomite cement (SM-78). • 71 • 1- • t 1 -..-.,(Wl." -.cil Flgu,. 3·7e:: Frequenc:y DlalflbuUon of T" Data for Spray Lalle La" Doloml" ,i' ...of' .fI ,,'IJ . ~~~~~~~~~~~~~~~~~~~~~ • .....,.1MCl1 Chapter 3: DEVONIAN OUTCROPS OFltIE ROCKY MOUNTAINS; A.UID INCLUSION AND ISOTOPE DATA crystalline, blocky white calcite spar. The calcite cement thus postdates the coarsely • crystalline dolomite phase (see Mattes and Mountjoy, 1980). The 87Sr/86Sr of the calcite 18 cement is 0.71125, 0 0 = -11.67, and ol3C = -11.35, while the dolomite cement has 18 87Srl~6Sr of 0.71057.0 0 = -8.1S, and ol3C = -3.76. Mountjoy et al. (1992) reported similar 87Sr/86Sr values (i.e., 0.7105 and 0.710S) for two saddle dolomite samples from the Miette buildup. !\tIAIN RANGES Vug. mold. and fracture-filling calcites (n=5). as weil as mold and fracture-filling saddle dolomites (n=2), were sampled from four Main Range Devonian outcrop locations. Three late-diagenetic calcite cements and one saddle dolomite from the Southesk and Palliser Formations in the Simpson Pass thrust sheet near the Columbia Ice Fields were subjected to tluid inclusion and isotopie analyses (Fig. 1-3). Two more calcites and a saddle dolomite from Riee Brook were tested for 87Sr/86Sr. 0180. and ÔI3C. Parker's Ridge A coarse, late-stage, vug-filling calcite cement from the northwest Southesk Cairn buildup margin from Grotto Member of the Southesk Fonnation at the crest of Parker's Ridge (Fig. 1-3) was analysed (Figs. 3-8a and b). Primary inclusions within the calcite have relatively consistent fluid/vapor ratios of between 0.S5 and 0.9. The average Th for the calcite is 139.6°C (n=19). Of the Devonian outcrop samples analysed in this work, this calcite contained the most saline fluids with an average of 19.7 wt% NaCI equivalent • (n=12). There is no correlation between homogenization temperature and salinity (Fig. 3- 72 Ctupt~r 3: DEVONIAN OlJTCROPS OFllŒ ROCKY MOUNTAINS- FLUID INCLUSION AND ISOTOPE DATA • 10). The calcite yielded 87Sr/86Sr of 0.71058, 0180 of -11.20, and ô13C of -23.64. Big Hill A very coarsely-crystalline, late-stage, vug-filling calcite cement sample from Palliser strata exposed at the Big Hill section (Fig. 1-3) was also analysed (Figs. 3-8c and d). Primary inclusions within the calcites have consistent fluidlvapor ratios of 0.9. The average Th for this sample is 133.9°C (n= (5). The salinity of the f1uids trapped in the inclusions is similar to that of the Parker's Ridge calcite (average = 19.4 wt% NaCI equivalent. n=II). Unlike the Parker's Ridge calcite there is a positive correlation between homogenization temperature and salinity data (Fig. 3-10). The calcite yielded 87Sr/86Sr of 0.70926. Ôl80 of -11.31, and ô13C of -11.32. The Ôl3C is significantly more negative than that of the Parker's Ridge calcite. Cirrus Mountain Two late-stage. vein-filling cements (SM69 and 70) were sampled from the Ronde Member at the base of the Weeping Wall exposure at Cirrus Mountain (Fig. 1-6). SM69 is a coarsely crystalline saddle dolomite found in a brecciated zone commonly associated with 10 to 15 cm wide fractures that are sub-parallel to bedding and interpreted to he synthrusting. Primary inclusions within this cement have consistently small vapor bubbles with a f1uidlvapor (F) ratio of 0.9. The average Th for the primary fluid inclusion assemblage (FIA) examined in SM69 is 173.2 oC (Fig. 3-9a). The fluids within these inclusions have an average salinity of 17.0 wt% NaCI equivalent (Fig. 3-9b). • No correlation exists between formation fluid temperature and salinity (Fig. 3-10). 73 Chaplr:r 3: DEVONIAN OUTCROPS OF THE ROCKY MOUNTAINS' ELUID INCLUSION AND ISOTOPE DATA • Figure 3-8a: Frequency distribution of homogenization temperature data (see Appendix A. Table AB-3) for late-diagenetic calcite cement (SM-59) from Grotta Member outcrop at crest of Parker's Ridge in the Main Ranges. Figure 3-8b: Frequency distribution of salinity measurements (see Appendix A, Table A 3) from late-stage calcite cement (SM-59). Figure 3-8c: Frequency distribution of homogenization temperature data (see Appendix A. Table A-3) for late-diagenetic calcite cement (SM-60) from Palliser strata exposed at the Big Hill Section south of Parker's Ridge. Figure 3-8d: Frequency distribution of salinity measurements (see Appendix A, Table A 3) from late-stage calcite cement (SM-60). • 74 Figure :J~a: Frequency Distribution of T. Daca for Pull.". Aldge ule Calcite '0 '1 li r •t • Tt j :r = •l ]t : f 0' 3~b: lOi Figur. FreqUlncy Distribution or Sdnlty Daca fut' p.ner', Ridge laie C.lclte :1 1 ~ ~ dt l ,i ! 1 : r : 1 0 'lo 'lo .. ,,,"' ,,"' .IlL..Q -f'Q ....0 .,'lo .'lo ,." ,."' ,"' ,""' ," ,," ." ..."' ...."' -e-"' '\' ...' "' ..,"' '\ v"' ", s-,('M.' illICO Figure :J-k: Frequlncy DI,1rIbudoft of T" Daca for 8111 HII laie Calcl.. '0 l :! T 15 :1 0 F"tgur. 3~d: Frequenc:y D"tr~n of s.1In1tf D.III for lIig ..La" CaIcif8 ': 1 :t 1 1 2 j :! ~., ,.0 ...... , ..0 .....", ...... JI.,.0 ....Q ...... -f'0 ~ 0 ",">cO ~ -:-~ ., ...... ,.." .." -f''' .. rl. '\ro." .. '" .. • ...... ,II1I:I) Chapler 3: DEVONIAN OUTCROPS OF THE ROCKY MOUNTAINS; autD rNCLUSION AND ISOTOPE DATA • Figure 3·9a: Frequency distribution of homogenization temperature data (see Appendix A. Table A-3) for saddle dolomite cement (SM-69) from Ronde Member, base of Cirrus Mountain in the Main Ranges. Figure 3·9b: Frequency distribution of salinity measurements (see Appendix A. Table A 3) for saddle dolomite (SM-69). Figure 3·9c: Frequency distribution of homogenization temperature data (see Appendix A. Table A-3) for late-stage calcite cement (SM-70) from Ronde Member, base of Cirrus Mountain. Figure 3·9d: Frequency distribution of salinity measurements (see Appendix A, Table A 3) for late-stage calcite cement SM-70. • 75 • 3·1.; Frequency Diltribudon ofT.. D." tar CJrrua llount8ln Sadd" DoIomitll ur. 3..gb= Frequency Dlatrlbullon of Sallntty Da. tar C&rrua Mounta," SIIddle Dolo.... ur. 3"e: Fr.quency D.trlbution of Th DI. for Cirnli Mouncaln La" C.... ...rP ...oP ...~ ...,a ...~ ...... T__,...~ Ch;lptcr 3: DEVONIAN OUTCROPS OFnlE ROCKY MOUNTAINS- RUfO INCLUSION AND rSOTOPE OATA • Figure 3-10: Homogenization temperature versus freezing point depression for late-stage carbonate cements from 3 Main Range locations (Parker's Ridge. Big Hill. and Cirrus Mountain) (n=31, from 3 calcite and 1 saddle dolomite cement). Figure 3-11a: ô13C versus ôr80 for late stage carbonate cements from Devonian outcrops in the Front and Main Ranges of the Rocky Mountains. The two shaded gray circles are coarse blocky calcites from post-tectonic fractures at Disaster Point and Cirrus Mountain. Figure 3-11b: 87Sr/86Sr versus ~r80 for late stage carbonate cements from Devonian outcrops in the Front and Main Ranges of the Rocky Mountains. The two shaded gray circles are coarse blocky calcites from post-tectonic fractures at Disaster Point and Cirrus Mountain. • 76 Figure 3·10: T" y•• T1ft for liain Range $ample• -4 p- 0 0 1 0 • -8 ! ";:' -10 o li : ·12 i5. ~ c! .14 .. • ~ •.. \J . 'ë ~ °fJ ~ ';. -16 • c iU\J~- , 18 • .• 1-.. ·20 1 .5M59: Le • Parker's Ridge o 5M60: LC • Big Hill • 5M69: 50 - Cirrus Mtn. o SM70: CC - Cirrus Mtn. r ·22 1 ! 1 1 1 1 1 100 110 120 130 140 150 160 170 180 190 200 210 220 HamOienlution Tem~ture(T., "C) Figure 3·"a: 11SrJ'lSr VI. ci 1'0·Front and Main Rangel 0713 css. ~ css • Calcite 0712 o Dolomite + Saddle Dolomite 0711 ePR OMC FRONT RANGES OP - Oisaster Point CSS - Cold Sulphur Spring 0.710 TC - Toma Creek RB .RS SL- Spray Lakes .RS 'OSL """- MC - Marmot Cirque BH -w 0.709 MAIN BANGES PR - Parker's Ridge OCP BH - Big Hill CM - Cirrus Mountain 0.708 --_._-~------~---~---~ RB - Rice Brook ·20 ·16 .12 -8 o .5 " 0 ("A., PD8) Figure 3·" b: ô 13C YS. J "0 - Front and Main Rang•• a '---0-.-----...... ---""'"'t''t--.-----~-...... , OP Rf' CM -+ CM CP -+ css • css ·5 °MC ~e .10 .AB .sUc MC .... ('ll..PDB) SL·O SL -15 . -20 -25 -20 -16 -12 -8 o • cS "0 ('*o. PD8) Chapr~ 3: DEVONIAN OlJfCROPS OFTHE ROCKY MOUNTAINS- A.UIP INCLUSION AND ISOTOPE DATA Sample SM70 is medium-crystalline calcite cement from a fracture perpendicular • to bedding that indicates genesis in a tensional environment. Primary inclusions within this cement have consistently small vapor bubbles with a fluidlvapor (F) ratio of 0.9. The average Th for the primary tluid inclusion assemblage (RA) examined in SM70 is 104.7°C - considerably cooler than SM69 (Fig. 3-19c). The tluids within these inclusions have an average salinity of 10.1 wt% NaCI equivalent (Fig. 3-9d). There is no correlation between formation tluid temperature and salinity (Fig. 3-(0). The host fracture and the cement likely are post-thrusting. Rice Brook Two late calcites and one late-stage saddle dolomite cement from the Cairn Fonnation at Rice Brook were analysed isotopically. A coarsely-crystalline saddle dolomite filling a stromatoporoid mold has 87Sr/86Sr of 0.70961. Ôl80 of -9.21, and ô13e of -10.18. A coarsely crystalline calcite. also filling a stromatoporoid mold, has 87Sr/86Sr of 0.70939. ÔI~O of -11.49. and ôl3e of -7.38. and a fine to medium-crystalline fracture l8 l3 filling calcite yielded 87Sr/86Sr of 0.70938. Ô 0 of -17.60. and ô e of -11.35. Regional patterns among isotopic data collected for Front and Main Range samples are 18 l3 summarized in the next section and in Figures 3-11a (87Sr/86Sr vs. Ô 0) and 3-11b (ô e vs. 8180). Geochemical Evidence Among Devonian outcrop samples (Table 3-1, Fig. 3-11a) calcite and dolomite • cements filling tectonic fractures. vugs and molds contained the most elevated 87Sr/86Sr, 77 Chanter 3: DEVONIAN OUTCROPS OF11-IE ROCKY MOUNTAINS; A..UID INCLUSION AND ISOTOPE DATA with samples from a fracture at Cold Sulphur Spring yielding the highest ratio (calcite = • 0.71277, saddle dolomite =0.71283). Only these two samples have 87Sr/86Sr marginally greater than the MASRmAS (Maximum Sr Isotope Ratio of Basinal Shales - 0.7120). Unlike sorne of the deep subsurface late carbonate phases, the late calcites and dolomites analysed from outcrop locations do not reflect genesis from a strongly radiogenic tluid. The late-stage vug and fracture-filling cements frorn outcrop are generally Iighter in ô13C than those from the Swan Hills Simonette, but are very similar to those from Obed, suggesting that TSR also occurred in reservoirs prior to uplift of the Front and Main Ranges (Table 3-1, Fig. 3-11b). SISO values for outcrop samples are similar to or slightly lighter than from subsurface carbonate cements. Durial History of Front and Main Ranges The Devonian buildups that outcrop in the Front Ranges underwent progressive burial by marine sediments up to and during the Mississippian with only minor intervals of exposure and erosion (Mossop and Shetsen, (994). In the Early Triassic most Permian and sorne Carboniferous strata were eroded, especially in the eastem Front Ranges. During the early Mesozoic a long pcriod of slow marine sedimentation began that was punctuated by periods of erosion. The late Jurassic to late Cretaceous and early Teniary were characterized by rapid buna] with deposition of a thick clastic sequence that formed a wedge of sediment that thickened westward (Mossop and Shetsen, 1994). Subsequently, Cretaceous to Early Tertiary thrusting was followed by extension and uplift (Mattes and Mountjoy, 1980). The generalized burial history of the basin now exposed in the Front Ranges of the Rocky Mountains is shown in Figure 3-12. In order • to reasonably estimate maximum buria] for these Devonian strata, the large thicknesses 78 ChaRter 3: DEVONIAN OlJTCROPS OFTHE ROCKY MOUNTAINS' FLUID INCLUSION AND ISOTOPE DATA • Figure 3·12: Bunal history of Devonian buildups in the Front Ranges of the Rocky Mountains using compacted thicknesses from the Miette areu (Miette-McConnell thrust sheet). Oil window is assumed to he similar to that of the Alberta subsurface. Modified from Mattes and Mountjoy (1980), Mountjoy (1989). Temperatures are based on a surface temperature of ISoC and a geothermal gradient of 25°C/km. • 79 • Figure 3-12: Burial Curve for Front Range Outcrops of Devonian Strata DEVONIAN1 CAABONIFEROUS 1PERMIAN 1mlASSlC 1JURASSIC 1CRETAceous 1 TERTIAAY 1 TIME (Ma) 1000 (m] OOO------I~------+_-- 2000 AppraxlmOfed • - .... stOrT or oil & gos ...?... - , ~ wtndaw , , 10000'-----...~------r__~-~...,;'-- ...... ',' 12e~------~ , ~~ , ~-' , " :c .. ~ Onset of Hydrocarbon Eh 5000 Cracking & T. S. R. Cl , -.1 ------1'-- , , ... ? • Chanter 3: DEVONIAN OUTCROPS OFTHE ROCKY MOUNTAINS- FLurD INCLUSION AND ISOTOPE DATA eroded subsequent to the onset of mountain-building must he constrained. Unfortunately, • there are few stratigr,.phic markers that May be used to constrain this thickness. Majorowicz et al. (1990) used an early Oligocene erosional surface in the post orogenie Flathead Graben to estimate that 4 km of Cretaceous and possibly early Tertiary rocks were eroded from the southeastem Front Ranges prior to graben fill. However. outcrop samples in this thesis were collected much further nonh in the eastem pans of the Front Ranges and Main Ranges. Outcrop samples studied are from rocks that were originally situated downdip from reservoirs such as Obed and Simonette. The evidence from the adjacent subsurface (Chapter 2. section 2.3) indicates that nearly 3 km of overburden was likely removed by Tertiary erosion. Yet, further west (i.e.• 50 to 100 km. restored) at the locations sampled for this research. the clastic wedge may have been thinner. lndeed. the eastem Main Ranges May have had no Tertiary cover at ail, since their uplift is believed to have begun in the Early Cretaceous (Schultheis and Mountjoy. 1978). Organic maturity studies of Perdrix black shales exposed in the Front and Main Ranges also provides a constraint on maximum buriaI. Rock eva) and vitrinite retlectance analyses indicate organic matter in the Perdrix Formation at Marmot Cirque is ovennature (i.e.. Hl =0, Rm =1.35%; Van Buchem et al., 1996). Although dependent on the geothennal gradient, this datum indicates temperature and pressure conditions consistent with the upper portion of the oil and gas window. Tissot and Welle (1978) suggest that vitrinite reflectance data above 1.3% indicate a buriaJ environment conducive to wet gas generation. Unfortunately this type of data is limited for outcrop • locations and extrapolation across the extent of the Front and Main Ranges is tenuous. 80 • A LATE-STAGE CALCITE .~.,.. B LATE-STAGE CALCITE LATE-STAGE SADDLE DOLOMITE c LATE-STAGE SADDLE DOLOMITE Plate 4: A) Lare-stage synthrusting fracture-filling calcite from outcrop at Disaster Point (undernormallight.lowerhalfis stained with Alizarin Red-S. field ofview is 32 mm). B) Late stage synthrusting fracture-fiIling calcite and saddle dolomite phases from outcrop at Cold Sulphur Spring (normal 1ight. field ofview is 12 mm). C) Late-stage synthrusting fracture filling calcite and saddle dolomite phases al Cold SulphurSpring (polarized light. field ofview is 13mm). • 81 CHAPTER4 • SUMMARY AND CONCLUSIONS Fluid Inclusion Data Fluid inclusion data for both subsurface and outcrop are summarized in Table 4-1. Table 4-1 : Summary of Fluid Inclusion Data for ut..stage Carbonate Cements Obed Simonette Devonian Outcrop. Saddle Dolomite. T.. range (" C) 136.310148.0 133.210 161.9 159.210187,0 Avg. T" ("C) 142.1 151.5 HU (n) (11) (24) (24) Salinlty (wt.% NaCI) 20.1 to 21.4 19.61022.2 13.21018.9 Avg, SaliMy 20.8 20.9 17.1 (n) (7) (18) (16) ut••tage Dolomite Cements T" range ("C) 173.8 10 212.3 Avg. T" (OC) 193 (n) (11) Sahmty (wt.% NaCI) 18.0 to 19.8 Avg. SaJimty 18.6 (n) (9) ute-stage Calcite Cements: T" range ("C) 126.7 to 172.3 122.3 to 157.7 122.510155.1 'ii Avg. T" ("C) 146.5 140.4 139.1 '; mc :::J= (n> (140) (40) (45) ID= Salimly (wt.':'" NaCI) 16.9 to 21 .9 22.2 to 23.6 16.11020.4 Avg. Salinlty 19.7 22.7 19.0 11 (n) (96) (32) (30) T" range ("C) 128.5 to 214.0 la Col c Avg. T" ("C) 176.0 l~ (n) (46) - ! Salinity (wt.% NaCI) 13.2 la 19.0 Jc-::1 Avg. Saiinlty ~I 15.9 CIl ~ (n) (39) lia T" range ("C) 92.0 10 118.0 .!lm Avg. T" ("C) 105.6 c~ 0= (n) (19) J~ salinity (wt.% NaCI) 7.7 to 10.5 -.• :::J Avg. Salinity 9.2 ii (n) (10) lia • N.B. - Late-stage ~lcite cements for 00ed Mld Simonette .,. tram vugs .na fractures. CI"ml~r 4: SUMMARY AND CONCLUSIONS • For Obed calcites, there is a bimodal distribution of Th data. Most inclusions have Th between 127 and 152°C (Thl in Fig. 2-4a), while a second population of priffiary inclusions yields Th data between 154 and 172°C (Le., Th2). No paragenetic, texturai, or geochemical differences between the host cements for Thl and Th2 were identified. This indicates that at least sorne of the inclusions in the assemblage yielded a Th datum above the fonnation temperature of the host phase, likely as a result of stretching (see Appendix C). The overall average Th for this calcite phase is 146.5°C and the average salinity is 19.7 weight percent Nael equivalent. Inclusions in the single saddle dolomite yield an average Th of 142.loC. A plOl of average Th versus present-day burial depth (Fig. 2-6a) shows liltle correlation (Le., 0.41) between increased burial depth and homogenization temperature. The data, after pressure correction, plot near a geothermal gradient of about 20°C/km (Fig. 2-6b). Inclusions in these cements are between 16.9 and 21.9 wt% NaCl (n=96; Fig. 2-7), with the coarsest calcite crystals containing the least saline inclusions. Simonette For calcite samples from the Swan Hills Simonette Th is between 122.3 and 157.7°C (Table 4-1, Fig. 2-19). The two saddle dolomite samples studied yielded Th data between is 133.2 and 161.9°C. For the saddle dolomites there is a positive correlation between average homogenization temperature and burial depth. Calcites plot near a 20°C/km geothermal gradient when plotted versus estimated maximum burial depth, and the saddle dolomites suggest a gradient around 23°C (Fig 2-20b). Average salinity for • calcite samples is (22.7 wt% Nael (n=32) which is slightly more saline than for late-stage 83 CIJaptt'r 4: SUMMARY AND CONCLUSIONS saddle dolomites (20.9 wt% NaCl) (Fig. 2-24). For both calcites and saddle dolomites • there is a positive correlation between salinity and burial depth (Fig. 2-21) with a wide scatter of salinities at any one depth. There is a positive correlation between average Tm and Th for the two saddle dolomite samples. Front and Main Ranges The synthrusting calcites from Front and Main Range outcrops yielded a wide range of both Th and salinity data (Table 4-1). Despite having an average Th (163.4°C) weil within the range of the dataset for synthrusting calcites. the Toma Creek calcite sample contained by far the least saline fluid inclusions. 14.3 versus an average of 18.4 wt% NaCl for othcr similar samples. Fluids in the two fracture-filling saddle dolomites analysed have an average Th of 171.1 Oc and salinity of 17.1 wt% NaCI equivalent. A late dolomite cement filling a synthrusting fracture at Spray Lakes has the highest average Th of ail the samples studied (l93.0°C with average salinity = 18.6 wt% NaCI). Vug-filling calcites sampled at Spray Lakes, Parker's Ridge and Big Hill. yielded Th data very similar (128.0 to 155.1°C. n=45) to that from vug-filling cements at Qbed and Swan Hills. The post-thrusting fracture-filling calcites yielded the lowest Th and salinity of ail the cements studied (Table 4-1). Thus. synthrusting fracture filling cements yield slightly higher Th than late-stage subsurface cements, and vug-filling calcites from outcrops have Th very similar to those of subsurface samples; however. post-thrusting fracture-filling calcites have distinctly lower Th and salinities. GecK:hemical Eviden~e • The isotope data from the analyses are summarized in Table 4-2. 84 C"gptu4: SUMMARY AND CONCLUSIONS • The Qbed late-stage calcites studied have very high 87Sr/86Sr signatures (as high as 0.7252. Fig. 2-10), as reported by Machel et al. (1996). Late dolomites from Qbed (o=~) yielded 8ïSr/86Sr between 0.71010 and 0.71525. 87Sr/86Sr data for Qbed late calcites (0=29 from Patey, 1995) yield a strong east to west increasing trend over approximately 35 km (Fig. 2-11a). The concentration of elevated 87Sr/86Sr signatures (i.e. »MASRIBAS) near the western margin of the Qbed buildup may indicate possible fault control of this margin. In addition. 87Sr/86Sr signatures appear to positively correlate with Table 4-2: Summary of Isotope Cata Obed Leduc' Swan Hm. Simanette' Devonian Outetrops' (Frasnlan) (Frasnléltl) (Frasnlatv'Fammenian) s..ddle Dolomite: s'Je 3.8 ta -0.9 -1.3 to -10.2 51~0 -6.7 ta -13.6 -6.5 to -9.7 !7Srf6Sr 0.71182 ta 0.73697 0.7096 to 0.7128 n= 11 3 Late Dolomite Cement: s'3e 2.3 ta -0.8 2.7 -11.4 to -13.1 SI~O -4.0 ta -6.7 -9.1 -8.2 to -10.3 !l'Srf6Sr 0.7179 ta 0.71525 0.71939 0.7094 to 0.7106 n= 3 1 2 Late Calcite cement: iiCII "C 1: s'Je -0.3 to -23.6 ::1= CD= SilO -8.2 '0 -17.6 s'Je 1.1 ta -27.1 1.9toO.1 ia.- IJ7Sr~Sr 0.7086 to 0.7113 SUO -6.5 ta -11.87 -9.6'0 -12.8 ~! n= 6 8'Sr~Sr 0.7865 '0 0.7255 0.7288 to 0.7369 n= 24 8 CIl .!i.e s'3e Iii -0.4 '0 -10.5 i ! SilO -6.6 to -15.6 - ::1 IJ7SrJMlSr 0.7092 to 0.7128 CI)c-_ >01 n= 3 ~ .!ir lis S'3e -0.2 to -0.6 jl SilO -8.2 '0 -18.3 • ::1 81SrJMlSr 0.7085 to 0.7087 ii n= 2 Q" ~- 1- Patey ('995) 2- Duggan (1997) • 3- This study 85 C1rapter4: SlJMMARY AND CONCLUSIONS burial depth (Fig. 2-12a) which suggests the radiogenic source for their formation fluid • lies betow the reservoir. Samples that are enriched in 87Sr generally have more negative 3180 signatures (Fig. 2-13a). Obed late calcites have consistent 3180 between -6 and -12%(j (0=49). but exhibit I3 a \Vide range of cS C values (i.e.• 1 to -27%c). most probably due to TSR. The dolomites and a large group of the calcites have signatures that are markedly heavier (i.e.• at least +4.5c;fc) than a second group of calcites that yielded cS 13C between -11.4 and -27.1%c. Although there is a bimodal distribution of cS 13C data. no other geochemical or petrographie distinction between these calcites was established. However. a plot of Ôl3C versus depth shows an inverse relationship. with the lightest signatures occurring near the top of the Obed reservoir where TSR occurred ubove the water level (Fig. 2-12b). Simonette The saddle dolomites from the Swan Hills Simonette are moderately to strongly radiogenic (87Sr/86Sr = 0.7118 to 0.7370; Duggan, 1997). The 87Sr/86Sr values from late stage carbonate cements are even higher than those documented by Machel et al. (1996, 1999) for Obed, and are the most radiogenic-rich carbonate cements found in the basin to date. Although not nearly as marked as at Obed. a westward increasing trend in 87Sr/86Sr is present on a local scale in Simonette, especially amongst the saddle dolomites (Fig. 2 24b). In addition. Simonette saddle dolomites show a positive correlation between 87Srl~6Sr and the samples' proximity to faults within the reservoir (Duggan et al., 2001; in press). • Similar to Qbed samples, late-calcites with high 87Sr/86Sr generally yielded lighter 86 C1rapler4: SUMMARY AND CONCLUSIONS S180 signatures (Fig. 2-25a). This pattern is also evident amongst Simonette saddle • dolomites although the scatter of the data points is much greater than it is for late 13 diagenetic calcites. Both late calcites and saddle dolomites have heavy Ô C signatures relative ta Obed (-0.9 to 3.8~c) presumably because TSR reactions did not take place in this reservoir. Saddle dolomites from Simonette yielded a somewhat wider range of ÔI80 than the calcites (Le., -6.7 to -13.6%c versus -9.6 to -12.8%c, see Fig. 2-25b). Front and Main Ranges Among Devanian outcrop samples (Table 4-2) calcite and dolomite cements filling tectonic fractures. vugs and molds contained the most elevated 87Sr/86Sr values, with samples from a fracture at Cold Sulphur Spring yielding the highest ratio (calcite = 86 0.71277. saddle dolomite = 0.71283). Only these two samples have 87Sr/ Sr values marginally greater than the MASRmAS (Maximum Sr Isotope Ratio of Basinal Shales is about 0.7120). Unlike sorne of the deep subsurface late carbonate phases, the late calcites and dolomites analysed from outcrop locations do not reflect genesis from a strongly radiogenic f1uid. The late-stage vug and fracture-filling cements from outcrop are generally lighter in S13C than those from the Simonette, but are very similar ta those from Obed, suggesting that TSR also occurred in reservoirs that are now exposed in the Front and Main Ranges. S180 values for outcrop samples are similar ta or slightly Iighter than thase fram subsurface carbonate cements. Relationship to Durial History and Tectonism Homogenizatian temperature data for vug and fracture-filling cements at Obed • and Simonette (122.3 ta 172.3°C, n=216) suggest that late calcite and dolomite phases 87 Cllapt~r": SUMMARY .o\ND CONCLUSIONS were precipitated near maximum burial~ which was likely reached in the Paleocene (Fig. • 2-27). Dolomite phases always occur before the late calcites and therefore would have precipitated at somewhat shallower depths. The generally lighter Ô13C signatures of Obed late calcites also retlecl the greater burial depth reached by lhis reservoir~ in that the impact of TSR is very evident in the upper part of the buildup. This~ in tum~ suggests that formation temperatures in the Devonian rocks of the deepest part of the basin~ Iikely remained above 15ûoC for a considerable period of time. Late-stage vug and synthrusting fraclure-filling calcites from the Front and Main Ranges also retlect the legacy of very deep burial and generally have very light ô13C signatures. The vug and synthrusting fracture-filling carbonate cements from outcrop yielded formation temperatures above 122.5°C and as high as 214.0°C. Correcting Obed and Simonette data for pressure (see Appendix C) inereases the lower end of this range by approximately +15.0°C. These temperatures would have been experieneed by Devonian strata late in the burial history of the basin when host rocks were buried between 5 and 7 km in the subsurface, and 6 to 8 km (posssibly more) in the now tectonically uplifted Front Range portion of the basin. From Late Cretaceous to Early Tertiary time when Devonian strata were nearing maximum burial~ strata on the west side of the basin were eompressed and thrust eastward (Priee and Mountjoy. 1970). Deposition during the latter half of the Cretaceous increased the thickness of post-Devonian overburden significantly across the deep basin by approximately 4.0 to 5.5 km near the eastem margin of the foothills. Near the start of the Tertiary. there were brief periods of erosion. In the deep western portion of the basin~ • Late Cretaceous thrusting uplifted the basin strata now exposed in the Front and eastem 88 Cflaprn 4_" SUMMARY AND CONCLUSIONS Main Ranges, and created extensive shear fracture systems that are oriented sub-parallel • to bedding. l3 Post-thrusting fracture-filling calcites have Ô C values that are generally much lighter than other late-cements from Devonian outcrops. yielded the lowest Th and salinities, and cross-eut synthrusting veins at Disaster Point and Cirrus Mountain. This evidence suggests that these cements were precipitated from cooler, meteoric waters mixed with brines, and were the latest carbonate phase to precipitate in these areas. Subsequent to the cessation of the latest period of Cordilleran compression, strata in the thrust-fold belt were subjected to extension and sub-vertical faults and fractures developed. The extent of this fracturing in the subsurface needs to be documented. Timing of Cement Stages At Obed and the Swan Hills Simonette reservoir, hast strata for late-stage calcite and dolomite cements would have been within the temperature range indicated by Th data (126.7 to 172.3oC: Table 4-1) in the Late Cretaceous to Paleocene (Fig. 2-27), and possibly into the early Eocene. The Devonian rocks outcropping in the Front and Main Ranges Iikely reached maximum burial sooner, probably in the late Cretaceous in contrast to Paleocene in the subsurface, and given their generally higher Th. were eXPQsed to higher temperatures than the Qbed and Swan "ills Simonette reservoirs (Fig. 3-12). Calcite and dolomite cements filling these synthrusting fractures have Th between 141.5 and 214.0°C (avg. =176.9°C. n=81), suggesting that these phases were precipitated in the Late Cretaceous during thrusting. Vug-filling calcite samples from outcrops al Spray Lakes, Parker·s Ridge, and Big Hill yielded Th between 122.5 and 155.1oC (avg. = o • 139.1 C, n=45). While vug-filling cements are petrographically similar 10 synthrusting 89 Cllaelu.J: SUMMARY AND CONCLUSIONS fracture-filling calcites. their Th values are markedly lower. If these vugs were not • completely cemented by calcite prior to thrusting, one would expect the same high Th phases found in synthrusting fractures to be present, but they are absent. The evidence, therefore, suggests that these vug-filling cements were precipitated in the Late Cretaceous (Fig. 3-12), prior to synthrusting fracture-filling calcites. Post-thrusting fracture-tïlling calcite cements likely formed in the Eocene under a regional tensional regime (Priee, (994). Potential Fluid Sources and Constraints on Fluid Flow Late-stage carbonate cements from Devonian outcrops analysed in this work have low 87Sr/~6Sr and do not show the effects of a radiogenic-rich f1uid that precipitated sorne of the late calcites and dolomites at Qbed and Simonette. The relatively low 87Sr/86Sr signatures of outcrop samples in this study indicates that these Devonian strata were out of hydraulic communication with strongly radiogenic fluids and basement rocks. The low 87Sr/86Sr ratios of the samples from the Southesk-Caim reef complex do not support this reef complex as having acted as a conduit system for radiogenic Sr, as was interpreted by Machel el al. (1996, (999). The post-thrusting late calcites from Disaster Point and Cirrus Mountain (SM50 and SM70) exhibited low salinities, and Iikely precipitated l'rom basin tluids that were rnixed with meteoric waters in the post-thrusting, tensional environment of the Eocene. Situated at a greater distance from the edge of the defonned belt than the Qbed reef complex, late-calcite cement samples from Simonette have even higher 87Sr/86Sr signatures (as high as 0.7369; Mountjoy el al., 1999; Duggan el al., 2001). The • discovery of late-stage carbonates with even higher 87Sr/86Sr from other deeply buried 90 C1wpœr 4: SUMMARY AND CONCLUSIONS Devonian (Kaybob. Kaybob South; Green. 1999) reservoirs indicates that highly • radiogenic diagenetic tluids locally were more common in the deep Alberta Basin than previously shown. Machel et al. (1996) hypothesize that Sr-rich tluids may have been expelled from the Front and Main ranges of the Rocky Mountains during the Laramide orogeny. Highly radiogenic Proterozoic c1astics in the vicinity of Jasper were proposed as the source of radiogenic Sr. If these fluids did originate in the ProterozoÎC Miette Group (Machel et al.. 1996), they would likely have left their isotopie signatures within the Southesk-Caim reef complex that continues downdip. southwest of the Qbed promontory. and which has been advanced by Machel as the likely conduit system. Although this hypothesis remains to he more thoroughly tested, no trace of these radiogenic f1uids has yet been identified From outcrops in the Southesk Cairn reef complex. While tluids that passed through Proterozoic sedimentary rocks represent a possible source for the high 87Sr/86Sr values detected in Qbed late-calcites. it seems unlikely that these tluids would have been able to he travel such a considerable horizontal distance through the relatively tight FIume Platform that lies at the base of the Southesk Cairn Complex. Also. the projection of the Southesk Cairn in the Main Ranges is at least 100 km southeast of the Proterozoic outcrops near Jasper. Other possible radiogenic sources include the crystalline basement below these reef complexes. or 87Sr'86Sr enriched sediments derived From the basement. Although no rigorous structural analysis has been performed on the Obed 86 reservoir. the concentration of high 87Sr/ Sr signatures near the western margin of the • buildup suggests that faulting may have partly controlled its distribution. Duggan (1997) 91 Cllaplf!r4: SUMMARY AND CQNCLUSIONS and Duggan et al. (2001, in press) document sub-vertical fault-control of high 87Sr/~6Sr • dolomites at Simonette. Recent evidence fQr sub-vertical, fault-controlled, high 87Sr/tl6Sr, late-stage carbQnate cementatiQn in several deep basin reservoirs such as Swan Rills Simonette and Kaybob South (Duggan et al. 2001, in press, Green. 1999) shows that these fauhs extend to the base of Devonian strata and might therefore connect through fractures or faults tQ the nearby underlying Precambrian basement. Extensional faults and joints probably acted as conduits along which Sr-rich brines could flow upwards from depth. Thus. tluids in contact with highly radiogenic basement rock Iikely contributed to the high 87Sr/86Sr signatures observed in these deep-basin late-calcite cements. Faults and fractures. although difficult to map and recognize in the subsurface, appear to have controlled the distribution of radiogenic fluids derived from the basement rather than being squeezed out Qf strata downdip in the basin. CODf:lusiODS 1. MQst homQgenization temperatures for subsurface late dolomite and calcite cements range between 127 and 172°C, with the subsurface dolomites having about the same temperature ranges. Obed late calcites show a bimodal distribution with one population of 127-152°C and a second 154-172°C. Salinities for these dolomites range from 18 to 21 wt% NaCI and the late calcites from 17 to 23 wt% NaCI. Thus these late dolomite and calcite cements were fonned at temperatures within the oil and gas windows during progressive bunal from highly saline waters. 2. In outcrop dolomite cements show a higher range of Th from 159 to 212°C (avg. 171°C) than late calcites 122 to 155°C (avg. 139°C) and salinities are similar, 13 to • 20 wt% NaCl for dolomites and 16 to 20 wt% for late calcites. Higher Th values in 92 Ornpra": SUMMARY AND CONCLUSIONS dolomites appears to retlect deeper buria! temperatures than those that occurred in the • subsurface deep basin, whereas the outcrop late calcites may have precipitated under cooler temperatures during thrusting and uplift. 3. Synthrusting fracture fillings in outcrop exhibit a wide range of homogenization temperatures ranging from 128 to 214°C (average 176°C), overlapping both earlier late burial dolomite and deep burial calcite cements (point 2). The highest Th oceur in samples from Cold Sulphur Spring in the western Front Ranges and Spray Lakes (avg. = 193°C) in the central Front Ranges. Toma Creek calcites have the lowest salinities. 14.3 wt% Nael. 4. Late-stage calcites from Qbed generally have negative Sl3C values (-9.6 to -12.8%c) indicating that these calcites may have precipitated above the water table during TSR reactions. in the presence of methane ubove temperatures of about 120°C. Most of the late-stage dolomites in outcrop have negative ôDC values (-1.3 to -23.6%c) suggesting that they probably underwent TSR reactions but somewhat earHer than the subsurface carbonates. 5. Post-thrusting fraeture-filling calcites have Ôl3C values that are generally much lighter than other late cements, have the lowest Th and salinities and crosscut synthrusting fractures. This evidence suggests that these post-thrusting calcites precipitated from cooler. meteoric waters mixed with formation brines. probably during tectonÎC extension in the Eocene. They \Vere the latest carbonate cement to precipitate. 6. Late calcite cements in the Qbed and Swan Hills Simonette reservoirs have 87Sr/86Sr values as high as 0.7252 and 0.7370 respectively. At Simonette saddle • dolomites are moderately to strongly f".ldiogenic. The restricled distribution of radiogenie 93 Clrnpra J: SUMMARy AND CONCLUSIONS samples in the subsurface in conjunction with the regional geology suppons that the • radiogenic fluids \Vere derived from basement rocks and/or sediments derived from the basement and moved upwards along faults and fractures beneath the Qbed and Simonette fields. 7. In contrast, the outcrop samples have low to only slightly radiogenic Sr ranging from 0.7086 to 0.7128. Thus the outcrop samples from the Southesk-Caim reef complex were not in hydraulic connection \Vith radiogenic f1uids and were not a regional conduit for radiogenic Sr, as previously interpreted. 8. Temperatures of 130 and 1500 e represent depths of 5.5 and 6 km assuming a 20oe/km geothermal gradient, or depths of 3.7 and 4.3 km assuming a 25°C/km geothennal gradient. A depth of 4 km corresponds to an interval in the Late eretaceous on the burial curve for the Qbed and Simonette reservoirs and represents a reasonable estimate for the time when the late-stage dolomites and calcites were precipitated in the subsurface. Temperatures of 185°C and 175°e are estimated to have occurred al maximum burial during the late Paleocene for the Qbed and Swan Hills Simonette buildups. assuming a 25°C/km geothermal gradient and a surface temperature of 20oe. 9. Maximum burial of about 6 to 7 km was reached earlier in the Front Ranges as compression and uplift took place in the Late Cretaceous. Calculated maximum burlal temperatures reached 175 to 195°C assuming a 25°C/km geothennal gradient and a surface temperature of 20oe . • 94 • REFERENCES Amthor. J. E., Mountjoy. E. W., and Machel, H. G., 1993, Subsurface dolomites in Upper Devonian Leduc Formation buildups, central part of Rimbey-Meadowbrook reef trend. Alberta. Canada. Bulletin ofCanadian Petro[eum Geology, v. 41. 164-185. Amthor, J.E.. Mountjoy, E.W.. and Machel, H.G.• 1994. Regional-scale porosity and permeability variations in Upper Devonian Leduc buildups: implications for reservoir development and prediction in carbonates. ,\merican Association of Petroleul1l Geologists Bulletin, v. 78. p. 1541-1559. Andrawes. F. F. ~nd Gibson. E. K. 1r.. 1979. Release and analysis of gases from geological samples. American Mineralogist. v. 64, 453-463. Andrews. G.D.. 1989. Devonian Leduc outcrop reef-edge models and their potentiaJ seismic expression: in McMillan. NJ.• Embry. A.F. and Glass, 0.1.. eds.. Devonian of the World. Volume II. Canadian Society of Petroleum Geologists Memoir 14. p. 427-450. Aulstead. K. L.. and Spencer. R. J., 1985, Diagenesis of the Keg River Formation. northwestern Alberta: f1uid inclusion evidence. Bulletin of Canadian Petroleum Geology. v. 33. 167-183. Baadsgaard. H.• Chaplin, C., and Griffin. W.L.• 1986. Geochronolgy of the Glosemeia pegmatite, Froland, southem Norway. Norsk Geologisk Tidsskift, v.64, 111-119. Baldwin, B.• 1971. Ways of deciphering compacted sediments. Journal of Sedimentary Petr%gy, v. 41, p. 293-301. • Bodnar. R. 1.. 1992. Revised equation and table for freezing point depressions of H20- salt fluid inclusions (Abstract): PACROA IV, Foun/Z-Biennial Pan-Ameriean • Conference 011 Research on Fluid Inclusions. Program and Abstracts, Lake Arrowhead, CA, v. 14, p. 15. Brannon. 1. C.• Cole. S. C.. and Podosek. F. A.. 1995, Can aIl Mississippi Valley-type (MVT) ore deposits be radiometrically dated? International Field Conference on Carbonate-Hosted Lead-Zinc Deposits: St. Louis. Society ofEconomie Geologists (extended abstracts). p. 27-29. Bray. C. J. and Spooner. E. T. C.• 1989. Fluid inclusion volatile analysis using heated crushing (-105°C)/gas chromatography with in-series photoionization/thermal conductivity detectors and digital peak processing [abs). 2nd Bienllial Pan-A", Conf. Res. Fluid Inclusions. 2. 12-13. Burke. W.H.• Denison, R.E.• Hetherington. E.A.• Koepnick, R.B .• Nelson. H.F.• and Otto. 1.B., 1982. Variations of seawater 87Sr/86Sr throughout Phanerozoic time: Geology. v.l0, 516-519 Bustin. R. M.• Barnes, M.A, and Barnes, W.C., 1985. Diagenesis 10: Quantification and modeling of organic diagenesis. Geoscience Cananda. v. 12,4-21. Bustin. R. M., 1991. Organic Maturity in the western Canada sedimentary basin. International Journal ofCoal Geology. v. 19, p. 319-358. Cavell. P. A.• and H. G. MacheL 1997. Tectonic Expulsion of Fluids into the Obed Area of West-Central Alberta: Sr Isotopie Evidence for F1uid Pathway. Extent and Possible Sources. in Ross, G. M.• (compiler). 1997 Alhena Basement Transects \Vorkshop, LitllOprobe Repon # 59. Lithoprobe Secretariat, University of British • Columbia, p. 171-181. 96 Denison. R.E., Koepnick. R.B., Burke. W.H., Hetherington, E.A. and Fletcher. A., 1997• • Construction of the Silurian and Devonian seawater 87Sr/86Sr curve. Clzemical Geology. v. 140. p. 109-121. Dickinson. G.. 1953. Geological aspects of abnonnal reservoir pressures in Gulf coast Louisiana, Americall Association ofPetroleum Geologists Bulletin, v. 37, p. 410 432. Dix. G. R.. 1993, Patterns of burial- and tectonically controlled dolomitization in an upper Devonian fringing-reef complex: Leduc Fonnation, Peace River Arch acea, Alberta. Canada. Jounlal ofSedimel1tary Petr%gy, v. 63. p. 628-640. Drivet. E.. 1993. Diagenesis and reservoir characteristics of Upper Devonian Leduc dolostones. southern Rimbey-Meadowbrook reef trend, central Alberta. Unpublished M.Sc. thesis McGill University, Montreal. 114 p. Drivet. E.• and ~1ountjoy, E.W.. 1997. Dolomitization of the Leduc Formation (Upper Devonian), southem Rimbey-Meadowbrook reef trend, Alberta. JounIai of Sedimelltary Researcll, v. 67. p. 411-423. Duggan. J. P.. 1997. Sedimentology and diagenesis of Swan Hills Simonette oil field, west-central Alberta. Unpublished M.Sc. dissertation, McGill University, Montreal, 177p. Duggan. J.P., and E. W. Mountjoy, 1997: Lithofacies, Diagenesis. and Porosity of the Simonette Oil Reservoir, Beaverhill Lake Formation, Deep West-Central Albena Basin, Canada. CSPG-SEPM Joint Convention .. June 1997, Calgary, Program with abstfacts, p. 85. • Duggan, J. P., Mountjoy, E.W. and Stasiuk.. V., in press 2001, Fault-controlled 97 dolornitization at Swan Rills Simonette oil field (Devonian), deep basin west • central Albel1a. Canada. Sedimentology, v. 48. Dunnington. H.V.• 1967. Aspects of diagenesis and shape change in stylolitic limestone reservoirs. 7t/z World Petroleum Congress, 20, Mexico City. p. 339-352. Epstein. S., Graf, D.L., Degens, E.T.. 1964. Oxygen isotope studies on the origin of dolomites. In: Craigh, H., Miller, S.L., and Wasserberg, G.J. (eds.), Isotopie and cosmic chemistry. North-Holland Publishing Co., Amsterdam, 169-180. Green. D.. 1999. Dolomitization and bunal diagenesis of the Devonian of West-central Alberta deep basin: Kaybob South and Fox Creek (Swan Hills Formation) and Pine Creek (Leduc and \Vabamun Formations). Unpublished Ph.O. thesis, McGill University. 260p. Hitchon. B.• 1984. Geothennal gradients. hydrodynamics, and hydrocarbon occurrences, Alberta. Canada. AAPG Bulletin. v. 68, 713-743. Hollister. L. S.. M. L. Crawford. E. Roedder. R. C. Burruss, E. T. C., Spooner, and J. Touret. 1981. Practical aspects of microthermometry. In: Hollister, L. S. and M. L. Crawford eds.. Fluid Inclusions: applications to petrology, Mineralogical Association ofCanada. p. 278-304. Jansa. L.F.• and Fischbuch. N.R.. 1974. Evolution of a Middle and Upper Devonain sequence from a clastic coastal plain deltaic complex into overlyjng carbonate reef complexes and banks, Sturgeon-Mitsue area, Alberta. Geological Sllrvey of Canada. Memoir 234. 105 pp. Kaufrnan. J.. 1989. Sedimentology and diagenesis of the Swan Hills Formation (Middle • Upper Devonian), Rosevear Field, Alberta, Canada: implications for fossil fuel 98 exploration. Canadian Journal ofEanh Science, v. 33, p. 938-957. • Lind. I. L., 1993. Sylolites in chalk from Leg 130, Ontong Java Plateau. In: W. H. Berger and J. W. Kroenke, Mayer, L.A. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, v. 130. p. 445-451. Machel. H.G.. 1998, Gas souring by Thermochemical Sulfate Reduction at 140°C: Discussion. American Association of Petroleum Geologists Bulletin, v. 82, p. 1870-1873. Machel. H.G., 1999, Effects of groundwater flow on minerai diagenesis, with emphasis on carbonate aquifers. Hydrogeology Journal, v. 7, p. 94-107. Machel. H. G.. Cavell. P. A.. Patey. K. S., 1996. Isotopie evidence for carbonate cementation and recrystallization, and for tectonic expulsion of fluids into the Western Canada Sedimentary Basin. Geological Society of America Bulletin, v. 108.p.ll08-1119. Machel. H.G.. and Cavell, P.A., 1999. Low-flux, tectonically induced squeegee f1uid r'hot flash") into the Rocky Mountain Foreland Basin. Bulletin of Canadian Petroleum Geology. v. 47,510-533. Machel, H.G., and Mountjoy, E.W.. 1987, General constraints on extensive pervasive dolomitization and their application to the Devonian carbonates of western Canada. Bulletin ofCanadian Society Petroleum Geology, v. 35, 143-158. Majorowicz, J.A., Jones, f.W., Enman, M.E., Osadetz. K.G., and L.D. Stasiuk, 1990. Relationship between thermal maturation gradients and estimates of the thickness of the eroded foreland section. southem Alberta Plains. Canada. Marine and • Petroleum Geology. v. 7. 138-152. 99 Margara, K., 1976, Thickness of removed sedimentary rocks, paleopore pressure, and • paleotemperature, southwestem part of Western Canada basin. American Association ofPetrole1I11l Geologists Bulletin, v. 60, 554-565. Marquez. X., 1994. Reservoir geology of Upper Devonian Leduc buildups, deep Alberta basin. Unpublished Ph.D. thesis, McGill University, Montreal. 285p. Marquez, X., and Mountjoy, E.W., 1996. Microfractures due to overpressures caused by thermal cracking in well-sealed Upper Devonian reservoirs, deep Alberta Basin: AAPG Bulletin, v. 80, 570-588. Mattes. B.W.• and Mountjoy. E.W., 1980. Burial dolomitization of the Upper Devonian Miette buildup, Jasper National Park, Alberta, in Zenger, D.H., Dunham, J.B., and Ethington. R.L.• eds., Concepts and models of dolomitization, Society of Economie Paleontologists and Mineralogists, Special Publication. 28, p. 259-297. McCrea, J.M.. 1950. On the isotopie chemistry of carbonates and a paleothermometer scale, JOllnJal ofChemical Physics. v. 18,849-857. McLean. D.J.• and Mountjoy, E.W., 1994. Allocyclic control on late Devonian buildup development, southem Canadian Rocky Mountains. JoIlnlal of Sedimenlary Research. v. B64, 326-340. Meijer Dress, N.C., 1994. Devonian Elk Point Group of the Western Canada Sedimentary Basin. In: Mossop, G., and Shetsen, (compilers), Geologicai Atlas of the Western Canada Sedimentary Basin. Canadian Society of Petroleum Geologisls and the Alberta Research COllnci/. p. 129-148. Melim. L. A., Eberli, G. P., WaIgenwitz, F.. 2000, Diagenesis of the Miette Builup, • Devonian. Canada - Fabrics and Variability. In: P.W. Homewood and a.p. Eberli 100 eds. Genetic stratigraphy on the exploration and production scales: Case studies • from the Pennsylvanian of the Paradox Basin and the Upper Devonian of Alberta. ElfExplor. Prod.. Memoir 24. p. 269-284. Mossop, G., and Shetsen. L. 1994. Geologieal Atlas of the Western Canada Sedimentary Basin: CSPG/ARCjoint publication, 510 p. Mountjoy, E. W., 1960. Structure and stratigraphy of the Miette and adjacent areas, eastern Jasper National Park, Albena. Unpublished PhO Thesis. 249 p. Mountjoy. E.W.. 1989. Miette reef complex (Frasnian). Jasper National Park, Albena, in Geldsetzer. ed.. Reefs- Canada and adjacent areas. Canadian Society ofPetroleum Geologists. Memoir 13. p. 497-505. Mountjoy, E.W., 1994. Dolomitization and the character of hydrocarbon reservoirs; Devonian of western Canada. In: A. Parker and B.W. Seliwood. eds.• Quantitative diagenesis. recent development and applications to reservoir geology. Dordrecht. KJuwer Academie Publishers, p. 33-94. Mountjoy. E.W.. and Amthor. J.E.• 1994. Has hurlai dolomitization come of age? Sorne answers from the Western Canada sedimentary basin. In: B. Purser. M. Tucker, and D. Zenager (eds.). Dolomites: a volume in honour of Dolomieu. International Association of Sedimentarologists Special Publication. no. 21, 203-229. Mountjoy, E.\V., Green. D.G., Duggan. J.P., and Smith. S.G.W., 1997. Burlal fluids and heat flow regimes in the deep Albena basin; new C. 0 and Sr isotopes and fluid inclusion evidence from late cements: CSPG-SEPM Joint Convention. June 1-6. 1997. Calgary, Albena. Program with Abstracts, p. 200. • Mountjoy, E.W., and Halim-Dihardja. M.K.• 1991. Multiple phase fracture and fault- 101 controlled burial dolomitization, Upper Devonian Wabamun Group, Alberta. • Jounlal ofSedimentary Petrology. 61, p. 590-612. Mountjoy. E.W., Machel, H.a.• Green. D., Duggan. J.• and A.E. Williams-Jones, 1999. Devonian matrix dolomites and deep bunal carbonate cements: A comparison between the Rimbey-Meadowbrook reef trend and the deep basin of west-central Alberta. Bulletin ofCanadian Petroleum Geology, v. 47,487-509. Mountjoy. E.W.. and Mârquez. X.• 1997. Predicting reservoir properties in dolomites: Upper Devonian Leduc buildups. deep Alberta basin. In: J.A. Kupecz, J.A. Gluyas and S. Bloch (eds.). Reservoir Quality Prediction in Sandstones and Carbonates. Ameriean Association ofPetroleum Geologists Memoir 69. Chap. 17, p.267-306. Mountjoy. E.W.. Qing, H.. and McNutt. R.. 1992. Sr isotopic composition of Devonian dolomites. Western Canada Sedimentary Basin: significance regarding sources of dolomitizing tluids. Applied Geoehemisrry. 7. p. 59-75. Mountjoy. E. \V .. Qing. H.• Drivet. E.. Marquez. X.• Whittaker. S., and Williams-Jones, A.. 1997. Variable fluid and heat f10w regimes in three Devonian dolomite conduit systems. Western Canada Sedimentary Basin: Isotopie and Auid Inclusion evidence/constraints. In: Basin wide fluid f10w and diagenetic patterns: Integrated petrologic, geochemical, and hydrogeological considerations. Society of Economie Paleontologists and Mineralogists, Special Publication. no. 57, p. 119-137. Nesbitt. B. E. and Muehlenbachs, K., 1994, Paleohydrology of the Canadian Rockies and • origins of brines, Pb-Zn deposits and dolomitization in the Western Canada 102 Sedimentary Basin. Geology, v. 22, p. 243-246. • Nesbitt, B. E. and Muehlenbachs, K., 1997. Paleo-hydrology of Late Proterozoic Dnits of Southeastem Canadian Cordillera. America" JOllnzal ofScience, v. 297, p. 359 392. Nurkowski, J. R., 1984. Coal quaJity, coal rank variation and its relation to reconstructed overburden, Upper Cretaceous and Tertiary Plains coals, Albena, Canada. American Association ofPetrolellm Geologisls Bulletin. v. 68. p. 285-295. Oakes, C. S., R. J. Bodnar and J. M. Simonson. 1990, The system NaCI-CaCI;!-H20: I. The ice liquidus at 1 atm total pressure. Geochimica et Cosmoc!zimica Acta. v. 5~, p. 603-610. Ollenberger, L.R.. and Conis, A.L., 1996. Simonette Beaverhill lake oil pool: discovery history. reservoir characterization and depletion strategy. Canadian Society of Petroleum Geologisrs Conference: Calgary, Program and Abstracts. June 16 - 19. Patey, K. S., 1995, Facies. Stratigraphy. and diagenesis of the Upper Devonian Carbonates in the Obed Area. West-Central Alberta, Canada. Unpublished M.Sc. Thesis, University ofAlbena, Edmonton. Alberta, Canada. Priee. R.A.. 1994, Cordilleran Tectonics and the evolution of the Western Canada Sedimentary Basin. in Geologie Atlas of the Western Canada Sedimentary Basin. G. D. fvlossop and I. Shetsen (compilers), Canadian Society of Petroleum Geologisls and Albena Research Council (Calgary). p. 13-23. Priee. R.A. and Mountjoy, E.W., 1970, Geological structure of the Canadian Rocky Mountains between Bow and Athabasca rivers - a progress report, In Wheeler, • J.O., ed. Structure of the southem Canadian Cordillera. Geological Association of 103 Canada, sp. pap. 6, p. 7-25. • Roedder, E., 1984. Fluid Inclusions. Mineralogical Society of America Reviews in Mi neralogy. 12, 644p. Schmoker. J.W., and Halley, R.B .• 1982. Carbonate porosity versus depth: A predictable relation for South Florida. American Association of Petroleu1n Geologists Bulletin. v. 66. p. 2561-2570. Schultheis, N. H. and Mountjoy. E. W.• 1978. Cadomin conglomerate of western Alberta - a result of Cretaceous uplift of the Main Ranges. Bulletin of Canadian Petro/eum Ge%gy. v. 26. no. 3, p. 297-342. Sclater. J. G. and Christie, P. A. E. 1980. Continental stretching: an explanation of the post-mid-Cretaceous subsidence of the central North Sea Basin. JOliniai of Geophysical Research. v. 85. p. 3711-3739. Shields. M. J. and Geldsetzer, H. H. J.. 1992. The MacKenzie margin. Southesk-Caim carbonate complex: depositional history. stratal geometry and comparison with other Late Devonian platform margins. Bulletin ofCanadian Petroleu", Geology, 40. p. 274-303. Switzer. S. B.• Holland, W. G.. Christie, D. S., Graf, G. C., Hedinger, A. S., McAuley, R. J., Wierzbicki. R. A., Packard, J. J.. 1994, Devonian \Voodbend-Winterburn strata of the Western Canada Sedimentary Basin: Geologie Atlas of the Western Canada Sedimentary Basin. G. D. Mossop and 1. Shetsen (compïlers), Canadian Society ofPetro/ellm Geologisrs and ALberta Researclz Council (Calgary), p. 165-195. Taylor. R.S .• Mathews. W.H. and Kupseh, W.O., 1964, Chapter 13. In: McCrossan R.G. • and Glaister, R.P. eds., Geological History of Western Canada Atlas, Canadian 104 Society ofPetroleum Geologists, p. 191-195. • Tissal, B.P. and Welte, D.H., 1978. Petraleum fonnation and Occurrence. Springer Ver/ag. Tobin, R.C. and Claxton, B.L., 2000, Multidisciplinary thermal maturation studies using vitrinite reflectance and f1uid inclusion microthennometry: A new calibration of old techniques. American Association of Petroleu", Geologists Bulletin. v. 84, p.I647-1665. Van Buchem. F.. Eberli. a., Whalen, M., Mountjoy, E.W., and Homewood, P.. 1996. The basinal geochemical signature and platform margin geometries in the Upper Devonian mixed carbonate-siliciclastic system of Western Canada. Bulletin Society Geologique de France, v. 167, no. 6, p. 685 699. Van Buchem. F.S.P.. Chaix. M.. Eberli. a.p., Whalen, M.T., Masse, P. and Mountjoy, E. W., 2000, OUlcrop ta subsurface correlation of the Upper Devonian (Frasnian) based on the comparison of Miette and Redwater carbonate buildup margins. In: P.W. Hamewood and a.p. Eberli eds. Genetic stratigraphy on the exploration and production scales: Case studies from the Pennsylvanian of the Paradox Basin and the Upper Devonian of Alberta. Elf Exp/or. Prod.. Memoir 24. p. 225-267. Walls. R.A.. Mountjoy, E.\V., and Fritz. P., 1979. Isotopie composition and diagenetic history of carbonate cements in Devonian Golden Spike reef, Alberta. Geological Society ofAmerica Bulletin, v. 90. p. 963-982. • \Vere, R. W., Jr., R. J., Bodnar, P. M. Bethke and P. B., Barlon, 1979, A novel gas-flow 105 fluid inclusion heating 1 freezing stage. Geological Society ofAIPlerica. Abstracts • with Programs. v. Il, p. 539. Wendte. J.• H. Qing. J. J. Davis. S. L. O. Moore. Stasiuk. L. O. and G .• Ward. 1998. High-temperature saline (thermotlux) dolomitization of Devonian Swan Hills platfonn and bank carbonates. Wild River area. west-central Alberta. Bulletin of COlladiall Pelroleu", Geology. v. 46. p. 210-265. Williams. G.O. and Burke. C.f.. 1964. Upper Cretaceous. Chapter 12. In: McCrossan R.G. and Glaister. R.P. eds.• Geological History of Western Canada Atlas. Calladion Society ofPelrolellm Geologisls, p. 169-190. \Villiam-Jones, A.E.. Linnen. R.L.• and Khositanont. S.• 1987. A Short Course on the applications of Fluid Inclusion Techniques to the Sludy of Hydrothennal Ore Deposits. 173p. • 106 APPENDIX A- Fluid Inclusion Data Table A-1: Summary of Fluid Inclusion Data for Obed Samples (N.B.· Le = late calcite. LD = lale dolomite. SD = saddle dolomite) Weil Th (oC) o erator 7-15-52- 2w5 41 L 1 mlth • 4186.28 LC 149.0 Smith 4186.28 LC -14.5 18.2 147.8 Smith 4186.28 LC -13.0 16.9 148.7 Smith 4186.28 LC -14.0 17.8 148.7 Smith 4186.28 LC -14.9 18.6 126.7 Smith 4186.28 LC 142.6 Smith 4186.28 LC -14.7 18.4 141.3 Smith 4186.28 LC -13.4 17.3 139.4 Smith 4186.28 LC -14.4 18.1 151.7 Smith 4186.28 LC -13.2 17.1 127.5 Smith 4186.28 LC -14.2 18.0 145.3 Smith 4186.28 LC -14.8 18.5 145.3 Kranidiotis 4186.28 LC 143.6 Kranidiotis 4186.28 LC 142.6 Kranidiotis 4186.28 LC -14.3 18.0 156.0 Kranidiotis 4186.28 LC -14.4 18.1 163.5 Kranidiotis 4186.28 LC -14.3 18.0 157.2 Kranidiotis 4186.28 LC 164.3 Kranidiotis 4186.28 Le -14.4 18.1 153.5 Kranidiotis 7-18-52-24w5 4823.30 LC -18.5 21.3 140.3 Smith 4823.30 LC 143.5 Smith 4823.30 LC -18.3 21.2 140.5 Smith 4823.30 LC -17.4 20.5 142.5 Smith 4823.30 LC -17.8 20.8 136.0 Smith 4823.30 LC 139.7 Smith 4823.30 LC 134.9 Smith 4823.30 LC -16.1 19.5 138.3 Smith 4823.30 LC -18.7 21.5 135.4 Smith 4823.30 LC 136.9 Smith 4823.30 LC -19.3 21.9 144.6 Smith 4823.30 LC 139.8 Smith 4823.30 LC -18.7 21.5 142.7 Smith 4823.30 LC -17.4 20.5 141.2 Smith 4823.30 LC 143.8 Smith 7-18-52-24w5 4824.0 LC -16.5 19.8 148.5 Smith 4824.0 LC -16.9 20.1 146.5 Smith 4824.0 LC -18.3 21.2 143.5 Smith 4824.0 LC -18.5 21.3 143.0 Smith 4824.0 LC -17.8 20.8 141.5 Smith 4824.0 LC 152.0 Smith 4824.0 LC -18.2 21.1 149.6 Smith 4824.0 LC 151.0 Smith 4824.0 LC 149.3 Smith 4824.0 LC 144.1 Smith 4824.0 LC 170.2 Smith 4824.0 LC -17.1 20.3 165.0 Smith 4824.0 LC 169.5 Smith 4824.0 LC 168.6 Smith 4824.0 LC 165.3 Smith 4824.0 LC 165.5 Smith • 7-1-53-24w5 4523.7 Le -16.2 19.6 149.7 Smith Page 107 APPENDIX A - Fluid Inclusion Data Table A-1: Summary of Fluid Inclusion Data for Obed Samples (N.B. - Le:; tate calCite. LO = late dolomite. SO:; saddle dolomitel Weil Depth (m) Material Tf (oC) Tm (oC) (Wt% NaCI) Th (oC) Operator • 7-1-53-24w5 (cont'd) 4523.7 LC -15.6 19.1 144.4 Smith 4523.7 LC -16.7 20.0 150.3 Smith 4523.7 LC -16.5 19.8 143.4 Smith 4523.7 LC -16.8 20.1 147.0 Smith 4523.7 Le -16.7 20.0 145.0 Smith 4523.7 LC -16.2 19.6 150.0 Smith 4523.7 LC 147.5 Smith 4523.7 LC 147.0 Smith 4523.7 LC 146.0 Smith 4523.7 LC 142.9 Smith 4523.7 LC 160.2 Smith 4523.7 LC 158.0 Smith 4523.7 LC 162.1 Smith 4523.7 LC -15.6 19.1 154.5 Smith 4523.7 LC 164.4 Smith 4523.7 LC 161.5 Smith 14-23·53·23w5 4126.1 LC -16.6 19.9 149.0 Smith 4126.1 LC -17.2 20.4 151.5 Smith 4126.1 LC -17.3 20.4 127.5 Smith 4126.1 LC -17.4 20.5 130.0 Smith 4126.1 LC -18.0 21.0 135.0 Smith 4126.1 LC -17.8 20.8 137.5 Smith 4126.1 LC -17.1 20.3 143.1 Smith 4126.1 LC -17.2 20.4 139.5 Smith 4126.1 LC -17.9 20.9 142.0 Smith 41261 LC 159.0 Smith 4126.1 LC 144.2 Smith 11.13·54-23w5 4012.2 LC -17.8 20.8 136.0 Smith 4012.2 LC -16.8 20.1 132.0 Smith 4012.2 LC -17.4 20.5 138.9 Smith 4012.2 LC -17.5 20.6 139.6 Smith 4012.2 LC -16.6 19.9 130.5 Smith 4012.2 LC 137.0 Smith 4012.2 LC 136.5 Smith 4012.2 LC -17.8 20.8 127.0 Smith 4012.2 LC -16.9 20.1 135.0 Smith 4012.2 LC 143.2 Smith 4012.2 Le 141.5 Smith 4012.2 LC 140.6 Smith 9-23-54-23w5 39n.4 LC -18.3 21.2 148.5 Smith 39n.4 LC -18.2 21.1 142.7 Smith 39n.4 LC -18.4 21.3 138.3 Smith 39n.4 LC -16.7 20.0 141.5 Smith 3977.4 LC -15.0 18.6 138.9 Smith 39n.4 LC -16.3 19.7 146.5 Smith 39n.4 LC -15.7 19.2 142.3 Smith 3977.4 LC -15.7 19.2 139.2 Smith 39n.4 LC -17.9 20.9 157.4 Smith 39n.4 LC -17.4 20.5 154.0 Smith 39n.4 LC 155.0 Smith 39n.4 LC -18.1 21.0 165.7 Smith • 39n.4 LC 155.0 Smith Page 108 APPENOIX A- Fluid Inclusion Data Table A-1: Summary of Fluid Inclusion Data for Obed Samples (N.B. - Le = late calcite. LD =late dolomite. SO =saddle dolomite) Weil Oepth (m) Material Tf (oC) Tm (oC) (Wt% NaCI) Th (oC) Operator ~-ll~-?3w5 (Cont'd) 3977.4 Le -15.9 19.4 142.2 Smith • 11-35-54-23w5 4211.27 -16.1 19.5 145.8 Smith LC 4211.27 LC -16.5 19.8 148.3 Smith 4211.27 LC -17.2 20.4 138.0 Smith 4211.27 LC -16.3 19.7 132.6 Smith 4211.27 LC -16.8 20.1 143.5 Smith 4211.27 LC -15.6 19.1 135.0 Smith 4211.27 LC -15.1 18.7 134.5 Smith 4211.27 LC 147.3 Smith 4211.27 LC 147.5 Smith 4211.27 LC 141.5 Smith 11-35-54-23w5 4215.08 LC -16.6 19.9 143.2 Smith 4215.08 LC -16.8 20.1 141.5 Smith 4215.08 LC -16.5 19.8 139.0 Smith 4215.08 Le -16.2 19.6 134.9 Smith 4215.08 LC -16.4 19.8 147.0 Smith 4215.08 LC -16.1 19.5 139.3 Smith 4215.08 LC -16.6 19.9 143.0 Smith 4215.08 LC -16.8 20.1 142.6 Smith 4215.08 LC -17.3 20.4 141.8 Smith 4215.08 LC -17.2 20.4 145.3 Smith 11-3S-54-23wS 4225.14 LC -14.0 17.8 145.7 Smith 4225.14 LC -15.3 18.9 148.0 Smith 4225.14 LC -15.4 19.0 145.6 Smith 4225.14 Le -15.1 18.7 146.2 Smith 4226.14 LC -15.6 19.1 143.0 Smith 4227.14 LC -14.5 18.2 146.1 Smith 4228.14 LC -15.6 19.1 144.0 Smith 4225.14 LC 146.6 Smith 4226.14 LC -14.2 18.0 149.3 Smith 4227.14 LC -15.3 18.9 167.4 Smith 4228.14 LC -15.6 19.1 172.0 Smith 4225.14 LC -15.1 18.7 167.5 Smith 4226.14 LC 169.4 Smith 4227.14 LC -14.5 18.2 172.3 Smith 4225.14 Le 168.4 Smith 14-23-53-23wS 4126.10 SO -18.4 21.3 139.7 Smith 4126.10 50 -18.6 21.4 143.5 Smith 4126.10 SO -18.0 21.0 137.2 Smith 4126.10 SO -17.6 20.7 146.0 Smith 4126.10 50 -16.8 20.1 148.0 Smith 4126.10 50 139.0 Smith 4126.10 50 -17.2 20.4 140.4 Smith 4126.10 50 144.6 Smith 4126.10 50 140.3 5mith 4126.10 50 -18.3 21.2 147.6 Smith 4126.10 50 142.7 Smith • Page 109 APPENDIX A • Fluid Indusion Data Table A-2: Summary of Fluid Inclusion Data for Swan Hills Simonette Samples ..;w,..e.-;I..I pIIIJIII!I...,,,,,...__...D.epth Cm) Matenal Tf (oC) Tm (oC) (Wt% NaCI) Th (oC) Operator '6·02%4-26*5 3!05.0 Le -20.2 22.5 146.5 !;;mltn • 3805.0 LC -19.8 22.2 137.3 Smith 3805.0 LC -19.5 22.0 136.9 Smith 3805.0 LC -20.3 22.6 133.8 Smith 3805.0 LC -19.0 21.7 140.1 Smith 3805.0 LC 131.3 Smith 3805.0 LC 139.6 Smith 3806.0 LC 130.2 Smith 3805.0 LC 131.7 Smith 3805.0 LC -20.1 22.4 132.2 Smith 07-17-64-26WS------3800.6 -~LC .. -- --.- -~~.19.9 22.3------f32~b---·Smitti -.-- 3800.6 Le -17.2 20.4 129.0 Smith 3800.6 LC -20.6 22.8 135.3 Smith 3800.6 LC ·18.7 21.5 122.3 Smith 3800.6 LC -18.1 21.0 123.1 Smith 3800.6 LC -20.1 22.4 138.5 Smith 3800.6 LC -19.6 22.1 133.5 Smith 07-17-64-26W5 3800.6 LC -19.5 22.0 134.7 Smith 3800.6 LC -18.5 21.3 126.6 Smith 3800.6 Le -17.6 20.7 124.3 Smith ---3'U2-:--0---CC ·:H)-.-O'---2·"2~----14ô-.O--~-Smith"--~ 3842.0 Le 143.5 Smith 3842.0 LC -21.8 23.6 148.2 Smith 3842.0 LC -21.9 23.6 141.5 Smith 3842.0 LC -22.0 23.7 146.7 Smith 3842.0 LC -21.5 23.4 149.6 Smith 3842.0 LC -22.1 23.8 154.5 Smith 3842.0 LC -22.0 23.7 143.0 Smith 3842.0 LC -22.5 24.0 144.0 Smith 3842.0 LC -22.5 24.0 144.7 Smith 3842.0 LC -22.1 23.8 151.5 Smith 3842.0 LC -21.4 23.3 157.7 Smith 3842.0 LC -21.8 23.6 145.0 Smith 3842.0 LC -22.0 23.7 148.0 Smith 3842.0 LC -21.8 23.6 144.0 Smith 3842.0 LC 146.8 Smith 3842.0 LC -21.7 23.5 154.3 Smith 3842.0 LC -22.4 24.0 149.0 Smith 3842.0 LC 152.5 Smith 3842.0 LC 147.5 Smith -1-=-3--=2-=-6---=6~3-~2--=-6W:---=-c:=5-~----,3=-c:9=0-=2.-.,.1------=-L-:;;;C,------21 .3 23.2 121.5 Duggan 3902.1 LC -22.0 23.7 96.0 Duggan 3902.1 LC 104.0 Duggan 3902.1 LC -15.0 18.6 123.0 Duggan 3902.1 LC 132.0 Duggan 3902.1 LC -21.5 23.4 112.5 Duggan 3902.1 LC -21.3 23.2 113.0 Duggan 3902.1 LC -21.1 23.1 110.0 Duggan 3902.1 LC -22.0 23.7 104.0 Duggan 3902.1 LC -21.6 23.4 122.0 Duggan 3902.1 LC -21.8 23.6 127.0 Duggan 05-19-64-26W5 3861.1 LC 133.0 Duggan 3861.1 LC 135.0 Duggan 3861.1 LC 155.0 Duggan • 3861.1 LC 130.0 Duggan Page 110 APPENDIX A - Fluid Inclusion Oata Table A-2: Summary of Fluid Inclusion Data for Swan Hill. Simonette Sample• Weil De~th (m) Material Tf (oC) Tm (oC) (Wto'" NaCI) Th (oC) Operator 65-19%4-26005 (conrd) 3151.1 t2 112.6 Duggan 3861.1 LC 136.0 Duggan • 3861.1 LC 102.0 Duggan 3861.1 LC 121.0 Duggan 3861.1 Le 134.0 Duggan o1-23-64-21W5 3909.8 LC -22.0 23.1 126.0 Ouggan 3909.8 LC -22.0 23.1 120.0 Duggan 3909.8 Le -23.0 24.3 117.0 Duggan 3909.8 LC 105.0 Duggan 16-02-64-26W5 3725.0 LC 104.0 Duggan 3725.0 LC 132.0 Duggan 3725.0 LC 125.0 Duggan 3725.0 LC 102.0 Duggan 3725.0 LC 125.0 Duggan 07-17-64-26W5 3787.1 50 -17.3 20.4 154.9 Smith 3787.1 50 -16.5 19.8 152.0 Smith 3787.1 50 -17.5 20.6 149.7 Smith 3787.1 50 -18.0 21.0 153.8 Smith 3787.1 50 -16.2 19.6 149.3 Smith 3781.1 50 -16.6 19.9 161.9 Smith 3787.1 50 -16.9 20.1 133.2 Smith 3788.1 50 150.9 Smith 3789.1 50 150.7 Smith 3790.1 50 133.3 Smith 3791.1 SO 140.5 Smith 07-11-64-26W5 3800.0 50 -18.5 21.3 157.2 Smith 3800.0 SO -19.2 21.8 149.6 Smith 3800.0 50 -18.7 21.5 155.6 Smith 3800.0 50 -17.9 20.9 156.8 Smith 3800.0 50 -19.7 22.2 160.2 Smith 3800.0 50 -18.8 21.5 157.3 Smith 3800.0 50 -18.0 21.0 161.5 Smith 3800.0 50 -18.3 21.2 155.9 Smith 3800.0 50 -19.1 21.8 159.6 Smith 3800.0 SO 150.1 Smith 3800.0 SO 148.2 Smith 3800.0 50 147.5 Smith 3800.0 50 146.6 Smith ------'_._.. '_. --._- --.------_._.- 05-19-64-26W5 3861.1 50 148.0 Ouggan 3861.1 50 151.0 Duggan 3861.1 50 144.0 Ouggan 3861.1 50 174.0 Duggan 05-19-64-26W5 (confd) 3861.1 50 180.0 Ouggan 3861.1 50 139.0 Duggan 3861.1 SO 137.0 Ouggan 3861.1 50 190 Ouggan 16-02-64-26W5 3805.0 SO 146.5 Ouggan 3805.0 SO 149.3 Ouggan 3805.0 SO 144.5 Duggan 3805.0 50 148.3 Duggan 3805.0 SO 160.4 Ouggan • 3805.0 50 152.5 Oupgan Page 111 APPENOIX A- Fluid Inclusion Data Table A·3: Summary of Fluid Inclusion Data for Devonian Outcrop Samples Front R,nan Location Tf (oC) Tm (oC) 0 rator • Isas er oan rani lOIS (Palliser) SM-50 LC -5.4 8.4 104.5 Kranidiotis SM-50 LC -5.5 8.5 103.0 Kranidiotis SM-50 LC -4.9 7.7 106.0 Kranidiotis SM-50 LC 104.2 Kranidiotis SM-50 LC 104.0 Kranidiotis SM-50 LC -5.6 8.7 107.3 Kranidiotis SM-50 LC 107.0 Kranidiotis SM-50 LC -5.0 7.9 110.6 Kranidiotis Oisaster Point SM-53 LC -14.2 18.0 184.1 Smith (Palliser) SM-53 LC -14.2 18.0 185.4 Smith SM-53 LC -13.1 17.0 168.3 Smith SM-53 LC -13.9 17.7 193.5 Smith SM-53 LC -13.7 17.5 184.6 Smith SM-53 LC -14.0 17.8 186.9 Smith SM-53 LC -14.9 18.6 214.0 Smith SM-53 LC -14.8 18.5 206.3 Smith SM-53 LC -13.6 17.4 178.2 Smith SM-53 LC -14.5 18.2 192.3 Smith SM-53 LC -15.4 19.0 202.1 Smith SM-53 LC 198.3 Smith SM-53 LC 195.5 Smith SM-53 LC 185.9 Smith Cold Sulphur Spring SM54 LC -13.1 17.0 179.3 Smith (Palliser) SM54 LC 184.4 Smith SM54 LC -13.0 16.9 167.0 Smith SM54 LC -13.4 17.3 1n.6 Smith SM54 LC -13.2 17.1 183.3 Smith SM54 LC -13.8 17.6 187.1 Smith SM54 LC 190.0 Smith SM54 lC -14.0 17.8 189.2 Smith SM54 lC 178.6 Smith SM54 LC -14.4 18.1 190.7 Smith Cold Sulphur Spring SM54 SO -12.6 16.5 162.7 Smith (Palliser) SM54 SO -13.6 17.4 173.8 Smith SM54 SO -12.8 16.7 159.6 Smith SM54 SO -13.9 17.7 168.6 Smith SM54 SO -13.8 17.6 170.2 Smith SM54 SO -13.2 17.1 171.0 Smith SM54 SO 163.6 Smith SM54 SO -13.6 17.4 170.8 Smith SM54 SO -14.1 17.9 163.5 Smith SM54 SO 177.4 Smith SM54 SO 172.3 Smith Toma Creek MM5 lC -10.4 14.4 166.1 Kranidiotis (Peechee) MM5 LC -10.0 13.9 174.0 Kranidiotis MM5 LC -10.1 14.0 164.8 Kranidiotis MM5 lC -10.3 14.3 171.5 Kranidiotis MM5 LC 168.0 Kranidiotis MM5 Le -10.4 14.4 170.3 Kranidiotis • MM5 LC -10.5 14.5 128.5 Kranidiotis Page 112 APPENOIX A- Fluid Inclusion Data Table A-3: Summary of Fluid Inclusion Data for Devonian Outcrop Samples Ftont Ranges Location Sample# Material Tf (oC) Tm (oC) (Wt% NaCI) Th (oC) Operator • Toma Creek (cont'd) MM5 LC -10.1 14.0 168.2 Kranidiotis MM5 LC -9.3 13.2 168.5 Kranidiotis MM5 LC -10.1 14.0 141.5 Kranidiotis MM5 LC -10.6 14.6 165.5 Kranidiotis MM5 LC -10.5 14.5 168.1 Kranidiotis MM5 LC -10.4 14.4 185.3 Kranidiotis MM5 LC -10.9 14.9 154.7 Kranidiotis MM5 LC -10.5 14.5 147.8 Kranidiotis MM5 LC 152.1 Kranidiotis MM5 LC -10.7 14.7 155.5 Smith MM5 LC -10.8 14.8 152.3 Smith MM5 LC -10.7 14.7 173.4 Smith MM5 LC -10.6 14.6 180.5 Smith MM5 LC -10.5 14.5 183.0 Smith MM5 LC -10.4 14.4 154.1 Smith MM5 LC -10.2 14.1 Smith Spray Lakes SM77 LC 146.7 Smith (Palliser) SM77 LC -12.2 16.1 149.3 Smith SM77 LC -13.7 17.5 139.6 Smith SM77 LC -13.6 17.4 146.2 Smith SM77 LC -13.2 17.1 133.6 Smith SM77 LC -13.0 16.9 148.9 Smith SM77 LC 151.2 Smith SM77 LC -12.7 16.6 149.4 Smith SM77 LC -13.3 17.2 145.3 Smith SM77 LC 144.7 Smith SMn LC 145.7 Smith Spray Lakes SM78 LD -14.6 18.3 174.9 Smith (Palliser) SM78 LD -15.2 18.8 202.4 Smith SM78 LD -15.1 18.7 194.3 Smith SM78 LD -15.0 18.6 212.3 Smith SM78 LD -16.5 19.8 196.8 Smith SM78 LD -14.6 18.3 194.3 Smith SM78 LD -14.7 18.4 199.2 Smith SM78 LD -14.8 18.5 173.8 Smith SM78 LD -14.2 18.0 189.4 Smith SM78 LD 187.2 Smith SM78 LD 198.8 Smith Main Ranaes Parker's Ridge SM59 LC -16.2 19.6 146.0 Smith (Grotto) SM59 LC -16.9 20.1 142.5 Smith SM59 LC -15.8 19.3 138.0 Smith SM59 LC -15.7 19.2 142.0 Smith SM59 LC -15.2 18.8 131.2 Smith SM59 LC -16.8 20.1 140.2 Smith SM59 LC -16.7 20.0 146.5 Smith SM59 LC -15.9 19.4 137.0 Smith SM59 LC -16.9 20.1 142.0 Smith SM59 LC -16.4 19.8 142.3 Smith • SM59 LC -16.9 20.1 122.5 Smith Page 113 APPENDIX A- Fluid Inclusion Data Table A-3: Summary of Fluid Inclusion Data for Devonian Outcrop Sampi•• Front Ranpe5 Location Sample# Material Tf (oC) Tm (oC) (Wt% NaCI) Th (oC) Operator • Parkers Ridge (cont'd) SM59 LC -17.2 20.4 136.5 Smith SM59 LC 130.5 Smith SM59 LC 144.4 Smith SM59 LC 145.2 Smith SM59 LC 147.2 Smith SM59 LC 155.1 Smith SM59 LC 132.0 Smith SM59 LC 130.5 Smith BigHi-lI- SM60 LC -16.5 19.8 138.2 Smith (Palliser) SM60 LC -16.4 19.8 130.7 Smith SM60 LC -14.1 17.9 131.6 Smith SM60 LC -16.9 20.1 137.1 Smith SM60 LC -16.6 19.9 136.3 Smith SM60 LC -15.8 19.3 130.7 Smith SM60 LC -15.0 18.6 129.2 Smith SM60 LC -16.4 19.8 136.9 Smith SM60 LC -16.3 19.7 133.0 Smith SM60 LC 136.6 Smith SM60 LC 133.3 Smith SM60 LC -16.2 19.6 134.5 Smith SM60 LC -15.1 18.7 132.1 Smith SM60 LC 140.5 Smith SM60 LC 128.0 Smith Cirrus Mountain SM69 50 -13.9 17.7 178.0 Kranidiotis (Ronde) SM69 50 -13.7 17.5 187.0 Kranidiotis SM69 50 -14.1 17.9 180.3 Kranidiotis SM69 50 -13.4 17.3 162.5 Kranidiotis SM69 50 -15.3 18.9 180.7 Kranidiotis SM69 50 -13.1 17.0 174.5 Kranidiotis SM69 50 -12.9 16.8 186.0 Smith SM69 SO -13.6 17.4 159.5 Smith SM69 SO -9.2 13.1 170.5 Smith SM69 50 172.5 Smith SM69 50 174.2 Smith SM69 50 168.9 Smith SM69 SO 159.2 Smith Cirrus Mountain SM70 LC -ô.9 10.4 109.0 Kranidiotis (Ronde) SM70 LC -ô.6 10.0 104.5 Kranidiotis SM70 LC -ô.8 10.2 102.0 Kranidiotis SM70 LC -7.0 10.5 112.0 Kranidiotis SM70 LC -6.3 9.6 108.7 Kranidiotis SM70 LC 96.0 Kranidiotis SM70 LC 92.0 Kranidiotis SM70 LC 98.0 Kranidiotis SM70 LC 118.0 Kranidiotis SM70 LC 106.4 Kranidiotis • Page 114 APPENOIX B- Isotope data Table 8-1: Summary of Isotope Data for Devonian Outcrop Sampies 13 Location Sampie 'II Matenal 87Srf 6 Sf' %SdErr 20- OHiO 8 cB • (..... POS) ('II.. POS) Front Ranges Disaster Point SM-50 CC 0.7086643 0.0011 0.00002 -18.34 -0.55 Disaster Point SM-53 CC 0.7091824 0.0007 0.00001 -6.64 -0.38 Cold Sulphur Spnng SM54 CC 0.7127709 0.0018 0.00003 -7.59 -2.06 Cold Sulphur Spnng SM54 SO 0.7128283 0.0014 0.00002 -6.53 -1.40 Toma Creek- MM5 CC 0.70918 Spray Lakes SM77 CC 0.7086042 0.0009 0.00001 -10.82 -12.31 Spray Lakes SM78 LO 0.709399 0.0006 0.00001 -10.27 -13.09 Marmot Cirque M1 CC 0.7112516 0.0006 0.00001 -11.67 -11.35 Marmot Cirque M2 SO 0.7105739 0.0008 0.00001 -8.18 -3.76 Main Ranges Parker's Ridge SM59 CC 0.7105759 0.0006 0.00001 -11.20 -23.64 Big Hill SM60 CC 0.7092649 0.0009 0.00001 -11.31 -11.32 Cirrus Mountain SM69 LD 0.7100895 0.0007 0.00001 -9.65 -1.31 Cirrus Mountain SM70 CC 0.7085028 0.0005 0.00001 -8.20 -0.18 Rice Brook RB1 CC 0.7093772 0.0008 0.00001 -17.60 -0.32 Rice Brook RB2 50 0.7096141 0.0008 0.00001 -9.21 -10.19 Rice Brook RB3 CC 0.7093901 0.0011 0.00002 -11.49 -7.38 A- Sr Isotopes were analysed at the University of Quèbec at Montrèal 8 - C and 0 IsotOpes were analysed at the University of Michigan •- For Isotope data from Toma Cree!< late-stage calcites see Cavell and Machel (1997) • Page 115 APPENDIXC • RECOGNITION Of PRIMARY FLUID INCLUSIONS & PRESSURE CORRECTION OF Th DATA Recognition ofPrimary Fluid Inclusions The validity of any primary fluid inclusion study hinges upon the correct identification of fluid inclusions that are primary; that is, those inclusions that accurately reflect the environment that existed when these cements were precipitated. Primary fluid inclusions are trapped during the growth of the host minerai, and are commonly concentrated in planes parallel to crystal faces and delineate growth zones. Secondary inclusions are entrapped after the growth of the host minerai is complete and generally occur along healed fractures that eut crystal boundaries (i.e., they are commonly oriented perpendicular to crystal faces). Fluid inclusions occurring along healed fractures within single crystals are often referred to as pseudosecondary. and are believed to have formed during the growth of the crystal and thus do accurately represent the characteristics the fonnation fluid which precipitated the host phase. Tobin and Claxton (2000) summarize the variability in defonnation style for aqueous fluid inclusions in calcite and outline the predicted effect on inclusion cavity volume. fluid density, fluid composition and homogenization temperature. White, as Tobin and Claxton (2000) note. optical criteria used to distinguish stretched From undefonned or Ieaked inclusions (see Table C-1, From Williams-Jones et al., 1987) are limited and ambiguous, there are several methods that can be employed in a fluid inclusion study to ensure that primary inclusions are the focus of analysis. Firstly, as it is • more difficult to recognize primary inclusions when there are no crystal faces, it is oost to ..tw'ndù C: RECOGNITION OF PRIMARY R..UlD INCLUSIONS & PRESSURE CORRECTlON OF Tb DATA concentrate on the study of euhedral crystals. Anhedral crystals have commonly • undergone recrystallization, and thus primary inclusion destruction. Secondly, the clarity of the crystals analysed is also important, as c10udy ones owe their turbidity to an abundance of small secondary inclusions. Clear crystals generally contain larger inclusions and a higher proportion of primary inclusions. It follows, therefore, that successful fluid inclusion studies start with the collection of multiple samples from each site. Using these criteria, the fluid inclusion analyses presented in this thesis focus on the quality of data over quantity. A comprehensive list of optical criteria used to identify inclusions of primary origin can also be found in Roedder (1984). Table C-l: Criteria for Distinguishing Primary, Secondary, and Pseudosecondary Fluid Inclusions Criteria for Primary Origin l. Based on occurrence in a single crystal. with or without evidence of direction of growth or growth zonation. A. Occurrence as a single inclusion (or a small three·dimensional group of inclusions) in an otherwise inclusion·free crystal. B. Large size relative to that of the enclosing crystal. e.g.. with a diameter - 0.1 that of crystal. and panicularly severa) such inclusions. C. Isolated occurrence. away from other inclusions. for a distance of greater than. or equaJ to. 5 limes the diameter of the inclusion. D. Occurrence as pan of a random. three~imensional dislribution throughout the crystal. E. Disturbance of otherwise regular decorated dislocations surrounding the inclusion. particularly ifthey appear to radiate from il. F. Occurrence of daughter crystals (or accidentai salid inclusions) of the same phase(s) that occur as solid inclusions in the host crystal or as conternporaneous phases. G. Occurrence along a twin plane. but note that secondary or pseudosecondary inclusions can behave similarly. II. Based on occurrence in a single crystal showing evidence ofdirection of growth: A. Occurrence beyond (in the direction of growth) and sometimes immediately before extraneous solids visible on the outer surface. E. Occurrence. particularly as relatively large fiat inclusions, paraUel to an external crystal face, and near its center (i.e.• from "slarVation" of the growth al the center of the. crystal face). e.g.• much "hopper salt." • F. Occurrence in the core of a tabular crystal (e.g.. beryl). This may he merely an extreme case of previous item. G. Occurrence. panicularly as a row, along the boundary between two growth sections. III. Based on occurrence in a single crystal showing evidence of growth zonation (as delermined by colour. clarity. composition, X~ray darkening. trapped solid inclusions. etch zones. exsolution phases. etc.). A. Occurrence in random three-dimensional distribution. with different concentrations in adjacent zones (forming a surge ofsudden feathery or dendritic growth). B. Occurrence as subparallel groups (outlining growth directions). panicularly with differenl concentrations in adjacent zones. as in previous item C. Multiple occurrence in planar array(s) outlining a growth zone. (Note that if this is also a c1eavage direction. there is ambiguity). D. Occurrence on a surface from an episode ofetching thal interrupted normal crystal growth. IV. Based on gro~1h from a heterogeneous (i.e.. two-phase). or changing tluid. A. Planar arrays (as in III-C) or other occurrence in growth zones. in which the compositions of inclusions in adjacent zones are different (e.g.• gas inclusions in one and liquid in another. or oil and water. B. Planar arrays (as in IlI-C) in which trapping of sorne of the growth medium has occurred at points where the hast crystal has overgrown and surrounded adhering globules of the immiscible dispersed phase (e.g.• oil draplets or steam bubbles). C. Otherwise primary-appearing inclusions of a t1uid phase that is unlikely to be the mineral forming tluid. e.g.. mercury in calcite. oil in f1uorite. V. Based on occurrence in hasts other than single crystals (i.e.. intercrystalline inclusions). A. Occurrence on a compromise growth surface between two nonparallel crystals. (These inclusions have generally leaked could also he secondary.) B. Occurrence within polycrystalline hosts. e.g.• as pores in fine-grained dolomite. cavities within chalcedony-lined geodes ("enhydros"). vesicles in basait. or as crystal-lined vugs in metal depasits or pegmatite. (These last two are among the largest "inclusions," and have almost always leaked.) C. Occurrence in noncrystalline hosts (e.g.. gas bubbles in amber; vesicles in pumice). VI. Based on inclusion shape or size. A. In a given sample. larger size and/or equant shape. B. Negative crystal shape·-this is valid only in certain specifie samples; in other samples. bath primary or only the secondary inclusion may have negative crystal shape. Criteria for Secondary Origin 1. Occurrence as planar groups outlining heaJed fractures (c1eavage or otherwise) that come to the surface of crystal (note that movement of inclusions during recrystallization can cause dispersion. II. Very thin fiat; in process of necking dO\\ll (but note that necking down may occur either during • temperature decline or isothermally. in primary. secondary. or pseudosecondary inclusions). 118 :tporndir C: RECOGNITION OF PRlMARY FLUID INCLUSIONS & PRESSURE CORRECTlON OF Tb DATA III. Occurrence within a plane that differs compositionally from the rest of the crystal. e.g.• in cathodoluminescence. • VI. Primary inclusions with filling representative of secondary conditions. A. Located on secondary healed fracture; hence presumably refilled with later fluids. B. Decrepitated and rehealed after exposure to higher temperatures or lower external pressures than at time of trapping; new filling may have original composition but lower density. IV. Temperature of homogenization (Th) far below that of adjacent presumed primary inclusions in the same growth zone (on the basis that low-TII early primaries would he decrepitated by a much houer later stage of gro",1h; however. note that late-stage primaries and pseudosecondaries can he at any lower temperature. and barring decrepitation. primary inclusions can show an increase in Th with stage of formation). Criteria for Pseudosecondary Origin 1. Same occurrence as secondary inclusions. but outer end of the fracture visibly terminates at a growth surface within crystal (See Ill-C under "Primary" above). Frequently tapered in size. the largest indusions being ncar the outer termination. II. Generally more apt to be equam and of negative crystal shape than secondary inclusions in same sample (suggestive only). III. Occurrence as a result of the covering of etch pits crosscutting gro"1h zones. Pressure Correction of Tb Throughout this study, homogenization temperatures for 2 phase liquid-vapour (L-V) inclusions have been reponed as minimum temperatures of fonnation for the cements analysed. Where inclusions have been tTapped from a boiling f1uid (co-existing liquid + vapour) homogenization temperature equals the actual temperature of entrapment (i.e.. Th =Tt). However. the Th of a large majority of inclusions does not equal Tt and so data must be corrected for pressure changes subsequent to entrapment. The difference bet\\"een Tt and Th. or 'pressure correction' is a function of bath pressure and density, and can he determined if 1) it is possible to obtain the chemistry of the inclusion (i.e., 8 20- • NaCl. H~O-CO:, etc.), 2) entrapment pressure is known or can be reasonably estimated. 119 .-tDl!frtdix C: RECOGNmON OF PRIMARY FLUlD INCLUSIONS & PRESSURE CORRECTION OF Tb DATA The late-diagenetic cements from Devonian strata at Obed and Simonette were • fonned near maximum burial (Thm:u = 185 and 175. respectively). Maximum burlal for these buildups was likely 2700 and 2500m deeper than at present (Chapter 2. section 2.3). The burial reconstructions for Obed and Simonette were thus used to estimate entrapment pressure. Isochores and a solvus were calculated using the salinity data in Chapter 2 (section 2.1.6 and 2.2.5) on the assumption that the inclusions being studied represent simple H;!O-NaCI systems 1. This process yjelded temperatures at Tl that are approximately 15°C higher than the average Th for calcites and saddle dolomites at Obed (i.e., -140°C). The basic assumptions and the data obtained are shown below: ...1lIlm1cal SVSlem ,. H2O-NaO ...n.n1Cal Syslem Il ~~ ~Ical ::>ystem la l'1;lO-N TEMPERATURE PRESSURE TEMPERATURE PRESSURE TEMPERATURE PRESSURE ,oC) fNrwl ,oC) l\WIl .oC) I,*-I 130 4 lSO 5 170 7 I.e 192 160 1116 180 '81 ISO 380 170 367 190 355 160 56B 180 548 200 5JO \70 755 190 729 2TO 700& 180 :;,&3 200 910 220 878 190 t131 210 TOST 230 1053 200 1318 220 1272 2.e 1227 210 1506 230 1453 250 l.ao1 220 1694 2.ao 16Jo$ 230 1882 250 1815 240 2063 250 2257 I..nemiCal syStem 1$ t12O-NaO 10lem1cal SySlem II l''l2Q-Nael cnerrllcal System 1$ H20-~ EQI'l Of Slale Brown " urno Eqn of S~1Il Brown & Lamb E(JI Of Slalll. Brown & UlmD NaCl MOIalIIV. '278 NiICI MOIall!ya '278 NilO MOIality. 4278 MCIe FracllOf1 NaO- 0072 Mele Fraction NiICI. 0072 MOIli Fra:tJQn NaCI- 0 072 Welgl'll Percenl NaCI- 20 000 Wetgl'll Percent NaO- 20.000 Wetfl'lt Percenl NaCl. 20000 Vapor Oui Temperature- T300 C Vapor Out Temperature- lS00 C V~ Out Tempe~ure- 170.0 C ~nbcal Pani. 569 2 C CntK:al POInt- 569 2 C CnliQj POInt- 569 2 C Sulk ""OIar VOlume- 1933 8u1k MoIar VOlume- 19 62 Bulk MOIaf VOlume- 19 93 0enIltv- 1 082 Oreitv- T. 066 tler6tty.. 1 ()1&9 TEMPERATURE PRESSURE TEMPERATURE PRESSURE TEMPERATURE PRESSURE (oC) '-'l (oC) l\WIl laC) e-wl 130 4 'SO 5 170 7 1.e 195 160 187 1110 181 150 385 170 370 190 356 160 576 180 552 200 531 170 166 190 7J5 210 705 180 ri57 200 917 220 !IBO 190 Il47 210 1100 230 1055 200 1337 220 12S2 2.e 1229 210 1528 230 1465 250 1404 220 1718 2.ao 16&7 230 1909 250 1830 2.ao 209SI 250 2290 • 1 FLINCOR © (version 1.1.1) was used to construct the P-T plot. 120 .-tDP!ndix C: RECOGNITION OF PRIMARY FLUID INCLUSIONS & PRESSURE CORRECfION OFTb DATA The resulting pressure correction, although indicative of the higher pressure • conditions that existed at the time of formation, must however he treated critically and may contain significant error. The possible sources of error in the technique include the oversimplification of the chemical system (i.e.. it May not he simply H20-NaCI), the estimate used for entrapment pressure (i.e.. max burial), and difficulty inherent in determining the pressures gradient (i.e., hydrostatic 1 Iithostatic). Thus the correction merely serves to show the reader that the homogenization temperatures for late-stage cements from Devonian strata of the deep subsurface and outcrop likely underestimate the Tt. and therefore. fonnation temperature. REFERENCES IN APPENDICES Roedder, E., 1984. Fluid Inclusions. Mineralogical Society of America Reviews in Mineralogy. 12, 644p. Tobin, R.C. and Cla' vitrinite reflectance and tluid inclusion microthennometry: A new calibration of old techniques. AAPG Bulletin, v. 84, p.I647-1665. \Villiarn-Jones, A.E., Linnen, R.L.• and Khositanont. S., 1987. A Short Course on the applications of Fluid Inclusion Techniques to the Study of Hydrothermal Ore Deposits. 173p. • 121