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0

• PALEOCEANOGRAPHY OF THE UPPER DEVONIAN FAIRHOLME CARBONATE COMPLEX, KANANASKIS - BANFF AREA, ALBERTA

by Mark P. Mallamo

, ,

Department of Earth and Planetary Sciences i~ McGill University, Montreal November, 1995

" ~,

A Thesis submitted to the Faculty of Graduate Smdies and Research in partial fulfilment of the requirements of the degree of Doctor of Philosophy © Mai'k P. Mallamo 1995 ,,~

~'

1+1

National Library of Canada

Bibliothèque nationale du Canada

Acquisitions and Bibliographie services Branch

Direction des acquisitions et des services bibliographiques

395 Wel1i!'IQton Street

395. rue Wellington Ottawa (Ontario)

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The author has granted an' irrevocable non-exclusive licence allowing the National Library of Canada to reproduce,' loan, distribute or sell copies of hisjher thesis by any means and in any form or format, making this thesis available to interested persons.

The author retains ownership of . the copyright in hisjher thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without hisjher permission.

L'auteur a accordé une licence irrévocable et non exclusive permettant à la Bibliothèque nationale du Canada de reproduire, prêter, distribuer ou vendre des copies de sa thèse de quelque manière et sous quelque forme que ce soit pour mettre des exemplaires de cette thèse à la disposition des personnes intéressées.

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= ISBN 0-612-12428-2

Omada

• SHORT TITLE:

PALEOCEANOGRAPHY OF THE FA!RHOLME COMPLEX, KANANASKIS-BANFF, ALBERTA

i

~"

.

,!

1:

• ,

,

,II

,

i

• This thesis is dedicated to the memorie~ of -:::--

Arvid Geldsetzer and Dr. David Koblu.l(; they are sadly missed.

:

=

• VOLUME l



TABLE OF COl'ITENTS Volume 1 Page

xi

ABSTRACT

xiii

RÉSUMÉ

ACKNOWLEDGEMENTS

xv

PREFACE

xix

Thesis Format

xix

Original ContrIbutions to Knowledge

xxii

Future Work

xxvi xxviii

PAPERs AND ABSTRACTS -

CHAP'rER 1. GENERAL INTRODUCTION

1 1

,

Objectives 00

1

The Fairholme Carbonate Complex Regional Setting and Depositional History

5

:

Pièvious Work: Fairholme Complex

8

Methods

9

Limits to Knowledge References

,

10 12

CHAPTER 2•.sTRATIGRAPHY AND DEVELOPMENT OF THE FAIRHOLME CARBONATÈ-COlMPLEX ••.••••••••••••••••••••••••••.•••••••••••••••••••••••••••••••••••...• 17



PART 1: MIDDLE AND LATEDEVONIAN STRATIGRAPHY

Introduction

i17 17



11

Lithostratigraphy Carbonate Buildup Succession Basinal Succession

19 19 45

,

Biostratigraphy Conodont and Brachiopod Biostratigraphy

52 54

Summary

63

PART 2: THE DEVELOPMENT AND GEOMETRY OF THE WESTERN MARGIN OF THE FAlRHOLME CARBONATE COMPLEX

65

Introduction

65

Buildup Margin Geometry .....................................................•............... 70 : 71 Buildup Margins Buildup Development and Basin-Fill Relationships

82

Summary

93

References

:

95

CHAPTER 3. STROMATOPOROIDS OF THE FAlRHOLME GROuP•••••••••• 100

INTRODUCTION

100

Sample'collection, preservation, and identification

101

PART 1: SYSTEMATIC PALEONTOLOGY .. ~

103

FAMILYActinostromatidae Nicholson, 1886b Actinostroma clathratum Nicholson, 1886a Actinostroma papillosum (Bargatzky, 1881a) Actinostroma n. sp. A Aculatostroma ordinarum (Stearn 1961) Aculatostroma ordinarum var. A : Aculatostroma sp. A F."MILy Clathrodictyidae Kühn, 1939 Petridiostroma vesiculosum (Stearn 1961) Petridiostroma n. sp. A • FAMlLY Tienodicryidae Bogoyavlenskaya, 1965

:

:

: ; '"

0

, ;

103 103 107 111 112 114 115 119 119 121 125

,~





III

Atelodicl}'onfallax Lecompte. 1951 Hammaroslroma albenense Stearn. 1961 Hamrr.atostromaplaryfonne (Klovan. 1966) Schistodicryon sp

125 127 128 134

ORDER Amphiporida Rukhin, 1938 Amphipora ramosa (phillips, 1841)

135 135

FAMILY Hennatostromatidae Nestor, 1964 Trupetostroma warreni Parks, 1936 Trupetostroma papulosum Stearn 1962 Trupetostroma pycnostylotum Stearn 1962 Trupetostroma n. sp. A Hennatostroma parksi Lecompte 1952 Hennatostroma polymorphum Lecompte 1952

137 137 139 141 143 146 148

FAMILY Stictostromatidae Khalfina and YavorsJ-:y 1973 Sticrostroma maclareni Stearn 1966 Stictostromajasperense StearnJ975 Clathrocoilona crassitexta (Lecompte, 1951) Clathrocoilona sp. A Clathrocoilona n. sp. B

150 150 152 155 157 158

f'., :-:"

FAMILY Stachyoditidae Khromych, 1967 Stacl1Jodes costulata Lecompte, 1952

164 164

FAMILY Stromatoporidea Winchell, 1867 Stromatopora parksi Stearn, 1966b Stromatopora cygnea Stearn, 1963 Arctostroma contextum Stearn, 1963 Lineastroma sp.A Pseudotrupetostroma n. sp. A

166 166 168 169 171 172

, :,

:

FAMILY Syringostromellidae Stearn 1980 Salairella cooperi (Lecompte, 1952) Salairella sp. A

174 174 178

PART 2: STROMATOPOROID BJOSTRATIGRAPHY

181

,Introduction

181

Faunal Assemblages Assemblage A: Lower Fiume Fauna Assemblage B: Upper Flume-Lowennost Upper Cairn Fauna

181 184 185



iv Assemblage C: Lower Upper Cairn Fauna Assemblage D: Middle Upper Cairn STROMATOPORID Fauna Assemblage E: Upper Cairn Actinostroma Fauna The Grotto Member ofthe Sourhesk Fomuaion

187 189 191 194

Summary

194

References

196

Volume II CHAPTER 4. PALEOBIOLOGY OF PALEOZOIC STROMATOpOROmS ••.• 202 INTRODUCTION ....•.••••••.••.•••••••..•...••••..••.•••••••••..••.•....•.•••.••.•••••••••••.••••... 202 PART 1: STROMATOPOROID PALEOECOLOGY ••••••••...•..•..•.•••••.••••••••••..••..•..•..... 205

Introduction

'"

205

Growth Form Terminology

206

Stromatoporoid Growth Forros and. Environmental Zonation

206

Fairholme Stromatoporoid Spe-

c~

Frasnian-Farnennian boundary. The carbonate banks

wer~

briefly exposed and

subsequeli...::Y covered by silts and shallejw-water carbonates (Calmar-equivalent silt and Ronde respectively).



8



(6) Infilling of the Jasper Basin and Sasôenach Depression west of the former reef domain by westerly derived siliciclastics (Sassenach) associated with the AntIer Orogeny. (7) Final development of a regional carbonate ramp (palliser) followed by a regional transgression with anoxic sediments (Exshaw). The first six of these seven episodes are the concern of this study, vvith emphasis on the second, third, and fourth episodes, and will be discussed in funher detai! in Chapler 2 (part 2) with regard to the Banff - Kananaskis region. Previons Work:

F~holme Complex:

Most studies of the Fairholme Complex have concentrated on its northern margin adjacent to the Cline Channel (Dooge, 1966; Mcllreath and Jackson, 1978; Workum and Hedinger, 1987, 1992; Eliuk et al., 1987; Weissenberger, 1989, 1994) or its northeastern margin, particuIarily al the Burnt Timber Embayment (Workum and Hedinger, 1988a; McLean and Mountjoy, 1993). Paleogeographic reconstructions of the Fairholme Complex show only dashed lines .or question marks along its western ':,il

margin (Mountjoy, 1980; Geldsetzer, 1987). Moore's (1989) map shows the western margin more precisely, but is not accompanied by a discussion of evidence documenting this. margin. Mallamo and Geldsetzer (1991, 1992) provided a more complete documentation of the western margin in the Banff-Kanan2skis region. Belyea and McLaren (1956) established type sections for the Peechee, Grotto, and Arcs Members of the Southesk Formation at Wmteman Gap, near Canmore. Since that rime, a wealth of literature has. become av:rlIable for. outcrops within

th~ Bow

9



Corridor (Taylor, 1957; Beales and Brown, 1963; Belyea and Labrecque. 1972; Desbordes et Maurin, 1974; Weihmann and de Wit. 1979: Burrowes, 1979: Bloy et al., 1989; Geldsetzer and Mallamo. 1991).

Detailed geological maps (1:50,000 scale) of the Banff and Canmore areas have been published as part of the Bow/Athabasca project (Price and Mountjoy. 1970a. b. 1972a, b), and recently of Peter Lougheed Provincial Park and a ponion of Kananaskis Country (McMechan, 1988; 1989). Usher (1959), Bielenstein et al. (1971). and McMechan (1993) have published large-scale maps of ponions of the southem BanffKananaskis region. ",While the interior portion of the Fairholme Complex is "weIl known", that part of the complex lying south of the Bow River and east of the continental divide - in the KananaskislBanff area - is poorly known. Prior to the iniùaùon of this doctoral thesis research, only three shon notes had addressed the Fairholme Group in this area. Usher (1959) established the general limits of the carbonate bank facies; Work'UIll and ~

~

\~

Hedinger (1988b) sketched sorne of the sigriificant facies changes within the bank itself; ,

and Steam (1961) described stromatoporoids from this region. :...J' ....,\-

Methods

Atota! of seven'months were spent in the field (summers of 1989, 1990. 1991); twenty-seven localiùes (Appendix: A) were visited within the study area for the measurement of straùgraphic secùons and the collecùon of samples (lithologic. macroand microfossil). Details of fossil form, size, and associaùbn were especially noted, as

10



were stratigraphic structures and lithologies. The stratigraphic sections were selected on the basis of the following criteria: 1) Exposure of the contact of the Fairholme Group with the underlying sub-Devonian strata; 2) Complete exposure (uninterrupted by faults and/or folds) of the Fairholme Group and the overlying Sassenach Formatioil. In the laboratory, samples were cut, polished, and thin-sectioned for paleontologic and sedimentologic examination, with an emphasis on stromatoporoid taxonomy. Samples collected for conodont microfossils were digested and conodonts extracted using standard procedures in laboratories at the Institute of Sedimentary and Petroleum Geology (Calgary, Alberta), and at the University of Oregon (Eugene, Oregon). Skeletons of stromatoporoids and other macrofossils were analyzed for elemental concentrations on a microprobe at McGill University. Whole rock analyses of major and minor elements were performed in an XRF geochemical laboratory at McGill University. Organic and inorganic carbon analyses were performed at McGill University using a LECO induction furnace and a gravimetric absorption bulb; samples were ignited at 550·C. Stable isotope analyses were performed at the University of Michigan on a gas ratio mass spectrometer (Finnigan MAT 251) and sample reaction system.

Limits to Knowledge 1. While a great deal of information is available about Devonian geology



. northwest of Kananaskis Country and in the subsurface of Alberta and Saskatchewan, knowledge to the south and west is limited by the lack of outcrops or wells. JThe only

II



documented cratonic Devonian outcrops west of the Rock)' Mountain Trench are in the Purcell Mountains (Root. 1983. 1993). South of Elk Lakes Provincial Park. thrusting

-

-

does not bring Devonian strata to the surface until the Flathead Range (Priee. 1965) and Crowsnest Pass (Workum and Hedinger. 1992) 110 km away. 2. Like most fossils. conodont mierofossils are facies controlled and certain facies do not yield conodonts. Carbonate lithologies bearing stromatoporoids and any lithofacies representing agitated shallow subtidal, intertidal. or supratidal depostional environments rarely contain conodonts. Therefore. lithologiès of this nature were avoided in collecting samples for the extraction of conodonts. The Peechee and Arcs members were depositional units of the Fairholme Group that did not yield conodont microfossils; certain beds of the Cairn (stromatoporoid biofacies) and Sassenach formations, as well as the Grono and Ronde members rarely yielded conodonts. The Maligne, Perdrix and Mount Hawk formations and the coral biofacies of the Cairn Formation commonly yielded conodonts.

12



REFERENCES Beales, F.W. and Brown, P.R., 1963. Sawback Range Devonian secùon. Bulleùn of Canadian Petroleum Geology, v. 11, p. 238-260. Belyea, H.R. and Labrecque, J.A., 1972. Devonian straùgraphy and facies of the southern Rocky Mountains of Canada and the adjacent plains; XXIV Internaùonal Geological Congress, Guidebook, Field Excursion C-18. Belyea, H.R. and McLaren, D.J., 1956. Devonian sediments of Bow Valley and adjacent areas; Alberta Society of Petroleum Geologists, Sïxth Annual Field Conference Guidebook, p. 66-91. Bielenstein, H.U., Priee, R.A., and Jones, P.B., 1971. Geology of the SeebeKananaskis area, in: I.A.R. Halladay and D.H. Mathewson (eds.), A Guide to the Geology of the Eastern Cordillera Along the Trans_ Canada Highway between Calgary, Alberta, and Revelstoke, British Columbia~- Guide Book; The Alberta Society of Petroleum Geologists, Map. Bloy, G.R., Hunter, I.G., and Leggett, S.R., 1988. The Lower Fairholme reef complex (Cairn Formation), White Man Gap area, Canmore Alberta, in: H.H.J. Geldsetzer, N.P. James, and G.E. Tebbut (eds.), Reefs, Canada and Adjacent Area; Canadian Society ofPetroleum Geologists, Memoir 13, p. 399-403. Burrowes, Q.G., 1979. Devonian reef secùons and Upper Cambrian stratigraphy at Grassi Lakes near Whiteman Gap, Canmore, Alberta in: I. Weihmann (ed.), Canadian Society of Petroleum Geologists, Field Trip Guidebook, p. Dalhstrom, C.D.A., 1970. Structural.geology in the Eastern Margin of theCanadian Rock)' Mountains. Bulleùn of Canadian Petroleum Geology, v. 18, p. 332-406.. Desbordes, B., et Maurin, A.F., 1974. Trois exemples d'erode du Frasnien d'Alberta; Notes et Memoires de Compagne Francaise de Petroles (Total), p. 302-336.. . Dooge, J., 1966. The straùgraphy of an Upper Devonian carbonate-shale transition between the north and south Ram Rivers of the Canadian Rocky Mountains: Leidse Geologie MededoI., deel39, p. 1-53.

E,liuk, L.S., Dooge, J., and Andrews, G.D., 1987. Fairholme stratigraphy and facies, . Cripple Creek - Ram River area, Alberta; Second International Symposium on the Devonian System, Field Excursion 7A Guidebook.

13 Geldsetzer, H.H.J., 1987. Upper Devonian reef and basinal sedimentation. Western Alberta; Second International Symposium on tbe Devonian System, Calgary Alberta (Field Excursion B4); Canadian Society of Petroleum Geologists, 50 p. Geldsetzer, H.H.J. and Mallamo, M.P., 1991. The Devonian of the southern Rock)' Mountains; the Canmore area; in: P.L. Smith (ed.), A Field Guide ro cize Paleontology of Sourlzwesrem Canada; First Canadian Paleontological Conference, University of British Columbia, p. 83-102. Mal1amo, M.P. and Geldsetzer, H.H.J., 1991. The western margin of the Upper Devonian Fairholme reef complex, Banff-Kananaskis area, southwestern Alberta; in: Current Research, Pan B, Geological Survey of Canada Paper 9l-1B, p. 59-69. Mallamo, M.P. and Geldsetzer, H.H.J., 1992. The development and geometry of the western margin. of the Fairholme (Upper Devonian) Carbonate Complex. southwestern Alberta. Geological Survey of Canada Oil and Gas Forum '92. Calgary, Alberta, Program and Abstracts. p. 8. '~

McDreath, I.A. and Jackson, P.C. (eds.), 1978. The Fairb9lme Carbonate Complex at Hummingbird and CrippleCreek. Canadian Society of Petroleum Geologists, Field Trip Guidebook, 87 p. McDreath, I.A., and Shade, B.D., 1992. Geometry and evolution of the Upper Devonian Fairholme carbonate complex, Front Ranges, Alberta. AAPG Annual Convention, Calgary, AB, Program with Abstracts, p. 85. McLean, D.J., and Mountjoy, E.W., 1993. Stratigraphy and depositional history of the Burnt Timber Embayment, Fairholme Complex, Alberta. Bulletin of Canadian Petroleum Geology, v. 41, p. 290-306. McLean, D.J., and Mountjoy, E.W., 1994. Allocyclic control on Late Devonii;n buildup development, southern Canadian RockY 11ountains. Journal of,Sedimentary Resear~h, v. B64, p. 326-340. McMechan, M.E., 1988. Geology of Peter Lougheed Provincial Park, RockY Mountain Front Ranges, Alberta. Geological Survey of Canada Open File 2057. McMechan, M.E., 1989. Geology of tlJ.e McConnell thrust sheet in Bragg Creek rnap , area (821/15), Alberta. Geological "S~ey of Canada Open File 2107. McMechan, M.E., 1993. Geology of RockY Mounlain Foothills and Front Ranges in Karianaskis Country, southwest of Calgary, Alberta. Geological Survey of Canada Open File 2642.

~

14 Moore, P.F., 1989. The Kaskaskia sequence. reefs, platforms, and foredeeps. The Lower Kaskaskia sequence - Devonian Chapter 9, in: B.D. Ricketts (ed.), Western Canada SedimenIary Basin. A Case Hisrory; Canadian Society of Petroleum Geologists, p. 139-164. Morrow, D.W., and Geldsetzer, H.H.J. 1989. Devonian of the Eastern Cordillera, in: N.J. McMillan, A.F. Embry, and D.J. Glass (eds.), Devonian of the World, Vol. Ill; Canadian Society of Petroleum Geologists, Memoir 14, p. 85-121 [date of imprint 1988]. Mountjoy, E.W., 1980. Some questions about the development of Upper Devonian carbonate buildups (reefs), Western Canada. Bulletin of Canadian Petroleum Geology, v. 28, p. 315-344. Osadetz, K.G., 1989. Basin analysis applied to petroleum geology in Western Canada, Chapter 12, in: B.D. Ricketts (ed.), Western Canada SedimenIary Basin. A Case History; Canadian Society of Petroleum Geologists, p. 287-306. Price, R.A., 1965. Flathead map area, British Coumbia andc Alberta. Geological Survey of Canada, Memoir 337. Price, R.A. and Mountjoy, E.W., 1970a. Geology of the Banffmap sheet (east haIt), Alberta-British Columbia; 0eological Survey of Canada Map 1294A (Scale 1:50,000). Price, R.A. and Mountjoy, E.W., 1970b. Geology of the Banffmap sheet (west half), Alberta-British Columbia; Geological Survey of Canada Map 1295A (Scale 1:50,000). Priee, R.A. and Mountjoy, E.W., 1972a. Geology of the Canmore map sheet (east haIt), Alberta; Geological Survey of Canada Map 1265A (Scale 1:50,000). Priee, R.A. and Mountjoy, E.W., 1972b. Geology of the Canmore map sheet (west haIt), Alberta; Geological Survey of Canada Map 1266A (Scale 1:50,000). Root, K.G., 1983. Upper Proterozoie and Paleozoie stratigraphy, Delphine Creek area, southeastem British Columbia: Implications for the Purcell Arch, in: Current Research, Part B, Geological Survey of Canada, Paper 83-1B, p. 377-380. Root. K.G., 1993. Middle Devonian thrustbelt and foreland basin development in western Cana~.a. GACfMAC Joint Annual Meeting, Edmonton, Alberta, Program and AbstraetS, p. A90.

15 Stearn. C.W.. 1961. Devonian stromatoporoids from the Canadian Rock)' Mountains. Journal of Paleontology, v. 35. p. 932-948. Taylor, P.W., 1957. Revision of Devonian nomenclature in the Rock")' Mountains. Journal of Alberta Society ofPetroleum Geologists. v. 5. no. 8. p. 183-195. Usher, J.L., 1959. The geology of the western Front Ranges south of Bow River. Alberta; Alberta Society of Petroleum Geologists. Ninth Annual Field Conference Guidebook, p. 23-35. Weihmann, 1. and de Wit. R., 1979. Grassi Lakes - Whiteman Gap Field Trip Guidebook, Canadian Society of PetroleumGeologists, 59 p. Weissenberger, J.A.W., 1989. Sedimentology and preliminary conodont biostratigraphy of the Upper Devonian Fairholme Group, Nordegg area. WestCentral Alberta, Canada; in: N.J. McMillan, A.F. Embry, and D.J. Glass (eds.). Devonianofthe World, Vol. Œ; Canadian Society ofPetroleum Geologists, Memoir 14, p. 451-462 [date of imprint 1988]. Weissenberger, J.A.W., 1994. Frasnian reef and basinal strata of West Central Alberta: a combined sedimentological and biostratigraphic analysis. Bulletin of Canadian Petroleum Geology, v. 42, p. 1-25. Workum, R.H., 1978. Cripple Creek - A leewaid Leduc reef margin; in: I.A. McDreath and P.C. Jackson (eds.), The Fairholme Carbonate Complex at Hummingbird and Cripple Creek; Canadian Society of Petroleum Geologists Field Trip Guidebook, p. 74-87. cWorkum, R.H., 1983. Patterns within the Devonian of the Alberta Rocky Mountains as analogs to the subsurface; Canadian Society of Petroleum GeologislS Short Course. Workum, R.H., and Hedinger, A.S., 1987. Geology of the Devonian Fairholme Group, Cline Channel, Alberta; Second International Symposium on the Devonian System, Field Excursion A-6, Guidebook. Workum, R.H, and Hedinger, A.S., 1988a. Bumt Timber and Scalp Creek margins, Frasnian Fairholme Reef Complex;Alberta, in: H.H.J. Geldsetzer, N.P. James, and G.E. Tebbut (eds.), Reeft, Canada and Adjacent Area; Canadian Society of Petroleum Geologists, Memoir 13, p. 552-556. Workum, R.H. and Hedinger, A.S., 1988b. Kananaskis area Frasnian reefs, Alberta; in: H.H.J. Geldsetzer, N.P. James, and G.E. Tebbut (eds.), Reefs, Canada and Adjacent Area; Canadian Society of Petroleum Geologists, Memoir 13, p. 557-560.

16



Workum, R.H. and Hedinger, A.S., 1992. Devonian (Frasnian) stratigraphy, Rocky Moumain Front Ranges, Crowsnest Pass to Jasper. Alberta; Geologica1 Survey of Canada Open File 2509.

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17



CHAPTER2

STRATIGRAPHY AND DEVELOPMENT OF THE FAlRHOLME CARBONATE COMPLEX

This chapter is divided into two parts: (1) the stratigraphy of the Devonian unils mentioned in chapter 1, outlining detailed lithostratigraphy and biostratigraphy of the study area; and (2) the development and geometry of the western margin of the Fairholme carbonate complex. Appendix B contains measured thicknesses of ail formations and members examined in this study. Some of the stratigraphie sections described and referred to throughout the thesis are illustrated in this chapler or in Appendix B.

PART 1: MIDDLE AND LATE DEVONIAN STRATIGRAPHY Introduction Beach (1943) original1y proposed the term Fairholme Formation for the Frasnian carbonate' succession exposed in the Bow Valley west of Calgary near the study area. de Wit and McLaren (1950) modified the Fairholme unit by assigning the upper silty strata to the Alexo Formation. McLaren (1956) subsequently promoted the Fairholme to Group status and used it to encompass both the carbonate Creefal") and



clastic (basinal") successions, which are summarized in Figure 2.1 .

• UPPER DEVONIAN STRATIGRAPHY WEST CENTRAL ALBERTA SURFACE

AGE CAllllONIF.

CARBONAIE FACIES

,.,.=...

i

i

~

~ ...:l

~

00

~

MIIlDU DIlVONIAN

-

i 0

a.ASlIC FACIES

EXSHAW

EXSHAW

1111 11111111111

RONDE

~~ °0 ~'" ....

WABAMUN • .

~ p:mj~CH J !.

~

GROTIO

PEECEEE '.

UPPER MEMBER

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11111111111111 }.YAHATINDA

GRAMINIA

III 1111111111111111111111111 11111111111

~

ARCS

!"if.

CARBONAIE FACIES llANFP

SASSENACH

15'"

Ci

a.ASlIC FACIES

BANI'F

PALUSER

~

~

SUBSURFACE

MOUNTHAWK.

li

i--1 __ 515 Q

BLUERIDGE CALMAR

NISKU

IRETON

~~

LEDUC

8~ 0 -1

PERDRIX

DUVERNAY

~11~ COOKlNG LAKE

MALIGNE

~~

FLUME

11111

WATER.WAYS

SWANHILLS

ELK POINT GROUP ,,

Figure 2.1. Upper DeVOIÙan stratigraphy and correlation chan, west-central Alberta.

19 Lithostratigraphy The carbonate buildup succession of the Fairholme Group was subdivided by McLaren (1956) into the lower ("black reef") Cairn Formation and the upper ("white reef') Southesk Formation (Figure 2.2A). The basinal succession comprises a lower carbonate platform unit (FIume Formation) and overlying basin-fiU shale and limeston.: of the Perdrix and Mount Hawk Formations. The Fairholme Group is overlain by the Famennian si!ts and silly carbonates of the Sassenach Formation. Carbonate Buildup Succession

Cairn Formation - Fiume Member The Cairn Formation is generally a grey to dark grey fossiliferous dolomite. and has been subdivided into two members: Fiume and "Upper Member" (informai). Stromatoporoids are the dominant fossi! constituent within the Cairn Formation. Th.: FIume Member continues laterally as the FIume Formation beyond the buildups, below the basinal succession. This regional carbonate platform unit oIÙaps the West Alberta Ridge, overstepping Ordovician carbonate rocks along the western slope of the ridge (western part of study area) and Cambrian carbonates toward the ridge crest at Mount McDougall (eastern part of Kananaskis region). Thin lenses of Middle Devonian sediments of the Yahatinda Formation (Figure 2.2B) occur locally below the Fiume unit. The basal beds of the FIume Member contain brachiopod-crinoid-gastropod mudstone and. wackestone, and locally, a thin brown sandstone. The main portion of

.

.

the FIume is biostromal, consisting of stromatoporoid- and Amphipora-bearing

20

• Figure 2.2. A. Fairholme Group carbonate succession at Mount McDougall, Kananaskis Country, within the interior of the Fairholme Carbonate Complex. This section shows the. lower "dark reef' of the Cairn Formation (FI=Rume, Cn=Upper., Cairn) and the upper "light reef' of the Southesk Formation (pe=Peechee, Gr=Grotto interval. Ar=Arcs). The stromatoporoid./coral biofacies boimdary within' the Upper Cairn Member coincides with the "Cn". Note the light grey bioherms (b) with flanking beds within the coral biofacies. Al=Alexo Formation; Pa=Palliser. The total thickness of the Fairholme Group at Mount McDougall is 393.0 m. . B. The Yahatinda (Ya) - Rume (FI) unconformity at Fisher Peak, within the interior of the Fairholme Carbonate Complex. The Yahatinda beds contain breccia with larninated clasts. The overlying Rume lithology is a skeletallimestone (wackestone to floatstone) containing bulbous stromatoporoids (s).near the ,base ofthè Rtim~.

;



,>,'..

..~:

:

;

:

22 rudstones and floatstones, with thin microbiallaminite beds (Figure 2.31'.). These three lithofacies I)ccur (from the base) in order listed above, and bave been interpreted as shallowing-upward fifth-order parasequences by McLean and Mountjoy (1994). The thickness of the Fiume Member commonly ranges from 21 to 42 m, but exceeds 94 m in the Sundance Range. In outcrop sections, the contact with the overlying Upper Cairn member is often difficult to recognize. In the Kananaskis area, the Fiume Member lacks the cbaracteristic cheny beds described at Ancient Wail and Miette . buildu,?s

(Mountjoy

and

MacKenzie,

1974;

Mountjoy,

1965).

The

i

.'- stromatoporoid' lithofacies of the Fiume continues into the Upper Cairn member, but the !wo members are separâi:ed by distinctive, locally ocbre weathering, argillaceous

,.'.

and/or calcareous sbale marker beds, containing bracbiopod and crinoid fragments oUGAU,

WEST

1

CANYON CREEK

/J

1

C

EAST

1

1

C ,!

CON.; MTN.

RM4b-6

1

";.::t' .:~~/:~L_'·. ;/

C

1

S

'~'o:'~

~

"'li'~ j':0 300

m) to be filled by siliciclastics of the Sassenach

Formation during early Famennian time (Figures 2.7, 2.16, 2.19 and 2.23).

66

• Figure 2.17. Upper Cairn paleogeography of the Fairholme carbonate complex. This

palinspastically-restored map of the study area shows the distribution of the stromatoporoid and coral biofacies, and the equivalent Perdrix "basinal" area. The light shaded line marks the transition from the shallow platform associated with the stromatoporoid biofacies to the relatively deeper water mid-ramp setting associated with the coral biofacies. The dark shaded line marks the transition from the carbonate ramp setting of the coral biofacies to the more "basinal" or distal foreslope setting of :>: ':::::...::--

the Perdrix"Formation.

-

ft --, , ,

"1"œ

\ .. _ ,UII"OO'

~

~

ul"OO'

Banff

Canmore



\

-;-'---7

PLATF~RM INTERIOR

:Ond Min. Ii

, • •, ,

STROMATOPOROID \ BIOFACIES

.'

Moose Min. '1"

-~~~~,

Ml

,

,,

McDougall

~

. ,

1>

1>

1

,

,

l

, ... "

-,

• 1

' .. 1

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Fisher Peak

MID·RAMP

... '",

\

CORAL BIOFACIES

FAIRHOLME CARBONATE COMPLEX Upper Cairn Member Paleogeog raphy PlatfoTTII Margln

Ramp-Basln Transition

Il),

~,

o

20 km

,,

40

N

A

68

• Figure 2.18. Peechee paleogeography of the Fairholme carbonate complex. The light shaded line marks the buildup margin separating the broad. very shallow buildup interior from the basinal setting (uppermost Perdrix and Mount Hawk formations}. Mount Shark (Sh) is located in the middle of the major re-entrant along the western margin herein named the Shark Embayment; its northern margin is weil exposed at Turbulent Creek (near Mount Turbulent, Tu), but its southern margin north of Mount Black Prince is poorly exposed. Other weIl exposed buildup margins defining the western margin include Fatigue Mountain and Mount Howard Douglas (B.D.), Copper Mountain, and Fossil Mountain.

e· =



• ')

m"OO'

m'OO'

Banff



Canmore "

End Min. A

INTERIOR Mt. McDougali

A

,, ,

, Moose Mto.

."~

-~~-~, . F ";', ;;( ,

~ \-co

A

Fisher Peak

Turoulent

C;;~k'~ X----. A ~Aru -

ConeA \ Min. Bh

~ 1lol'"

~~llpJ

BASIN

-d

Sllj\lt~

ll-~~~ ,

~i

\. ~ \\ "

1"

"\

'Ij,

\

"

... "

'...

/

A

- ....

1

,ÙJ""l

~

FAIRHOLME CARBONATE COMPLEX Peechee Member Paleogeography

A

Bulldllp Margln

o1

20

km

40

N

A

70



Buildup Margin Geometry Three buildup rnargins exposed within the Kananaskis - southern Banff area define the western rnargin of the FCC: Turbulent Creek headwaters (between Mount Mercer and Mount Turbulent). Fatigue Mountain. and Copper Mountain (Figures 2.17 and 2.18). North of Copper Mountain, a fourth rnargin is exposed at Fossil Mountain and Skoki Mountain and was observed by reconnaissance but not studied in any detail. Ail rnargins display the Cairn platforrn rarnp extending. and gradually thinning in a basinward direction. The Cairn platforrn rnargin was a distally-steepened carbonate rarnp, cornprised of three transitional facies: (i) a shallow. upper rarnp strornatoporoid platforrn interior; (ii) a rnid-rarnp coralline facies; and (iii) a black. organic-rich Perdrix basin (Figures 2.17 and 2.19). Figure 2.17 iIIustrates Upper Cairn paleogeography. The 'strornatoporoid platforrn rnargin trends in an east-west direction throughout most"\:lf the study area. The rarnp-to-basin transition trends west to east, but tums southward aImost 900 at the

Bour~eau

Thrust. Unfortunately, outcrop exposures

1

of FairhoIme sttata are lirnited south of Mount Joffre and west of Copper Mountain, and the continuation of the rnargin trend is uncertain. The Perdrix basinal lithologies near the rarnp-to-basin transition are carbonate-rich, but rnacrofauna are genernlly not corninon compared to the rnid-rarnp coral biofacies. The subsequent Peechee buildup developed into a more steeply sloping, rirnrned carbonate margin, which periodically shed reefaI blocks and debris flows downslope and into the Perdrix/Mount Hawk basin (Figure 2.19). Figure 2.18 illustrates Peechee



paleogeography. The buildup margin transition frorn interior to basin is considcrably more marked than the Upper Cairn margin. The western Peechee rnargin trends

71



irregularly southward to the Fatigue area where it turns in an easterly direction like the Upper Cairn margin. However. the Peechee margin extends farther eastward forrning a major re-entrant approximately 25 km wide. herein narned the Shark Embayment (Figures 2.7 and 2.19). From the Shark Embayment. the buildup margin trends southward parallel to the Bourgeau Thrust and coincident to the Upper Cairn rnargin. The northern rnargin of the Shark Ernbayment is well-defined at Turbulent Creek headwaters (Figures 2.13 and 2.20) and Fatigue Mountain (Figures 2.llA and 2.21). The southern rnargin of the ernbayrnent is poorly defined because of the lack of exposure caused by thrust faulting; its position is approxirnate based on McMechan's (1988) rnap. The eastern extent of the Shark Ernbayrnent is rnarked by exposures at The Fortress (Figure 2.7). At that locality, progradation of the Peechee buildup is evident. The Upper Cairn coral biofacies and Peechee lithologies are exposed on the north side of a cirque; carbonate-rich Perdrix and Mount Hawk foreslope lithologies, and Peechee platforrn lithologies are exposed on the south side of the cirque. The exact nature of this part of the rnargin is difficult to discern because of evidence of thrust fault repeats that disrupt Strata.

Buildup Margins Turbulent Margin

The south-facing Turbulent rnargin is exposed between Mount Mercer and Mount Turbulent at Turbulent Creek headwaters, near the southern end of Spray Lakes - "Reservoir in the southern part of Banff National Park (Figure 2.18 and 2.20A). The





Figure 2.19. Stratigraphie cross section C. Northwest-IO-southeast cross secti,)n of Fairholme strata illustrating-. the Turbulent margin along.. the ... and the Shark Emba"ment . Bourgeau Thrust Fault (refer 10 index map in Figure 2.5 for locations). The same cross section at two different scales is illustrated. Note the horizontal scale in the upper cross section; it is vertieally exaggerated 5x between the Turbulent margin and Tent Ridge. and greatly exaggerated at the other localities. Note the thinning of the Upper Cairn coral biofacies northward, and how most of the coral biofacies is replaced by the Perdrix Formation within the Shark Embayment. The south margin of the Shark Embayment is poorly exposed and is defined only from the section near Mt. Black Prince. The lower cross section is shown with no vertical exaggeration from Sundance Range South to Tent Ridge. Notiee the consistency in thickness

(c

carbonate buildup

depositional units, and the gently sloping ramp geometry of the Cairn Formation. The Sassenach (S) Formation overlying the buildup succession is too thin to illustrate, and is included in the Grono (G) - Arcs (A) - Ronde (R) interval. With the exception of the Peechee margin at Turbulent Creek, the intertonguing of buildup-to-basin strata in the upper cross section is only schematically illustrated in this manner to indicate the major facies change at this transition. The stratigraphie position of the base of the FIume between Turbulent Creek and Mt. Black Prince is uncertain due to thrust faulting. The Joffre Creek section was not measured by this author but the data was provided by M.E. McMechan (G.S.C. Calgary). The Turbulent 2 section was



measured by H. Geldsetzer during the field work part of this study.



w

CIl

.

--T-T~ ~

g- .!.

,

.,

?

~

,

-.~~--I

,

>. ~

Ï

gL

i

." ,••

è

~ '..1 ! ! i ! .g_

è

~ ~ ~!

i

! ~ r;-~

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;: ô411 ...." l.' ~

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V~ ii'~ !

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r" ~ r-~I;_- ~ • ,,il:'! .. 1 1

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~ ~ :;; s w

:

_,

"

Arctostroma contextum Hammatastrama p/atytonne • Ac/inos/rama n. op. A 1 .Hennatostrama parl" suggest sedimentation rates lower than those of the lower bed at 4.0 m.

In the environment of low

sedimentation rates, the genotypic plasticity of H. albenense allowed the individual to grow laterally into a laminar form, withoU! the consequence of being quickly buried in sediment. The genotype of P. vesiculosum may have been more restrictive. dictating only a domical growth form instead of a laminar form, and showing less sensitivity to the environment.

Case 2. At the South Ghost River 1 (End Mtn.) locality, 9 specimens representing 5 species were collected from the same bed in the FIume Member 25.9 m from its base:

Hammatoslroma albenense -laminar (2 specimens) Pelridioslroma vesiculosum - domical Trupeloslroma papulosum - bulbous (sealed) Aculatoslroma ordinatum - domical (2 specimens) , A. ordinalum var. A - domical, bulbous (sealed) Srromalopora parksi - domical Case 3. In the Upper Cairn Member at Mt. McDougall, 10 specimens were collected in a bed 93.1 m above the base

of

the Cairn Forml!.tion near the top of the ....:':":::"

stromatoporoid biofacies. The species identified from this stratum inc1ude:

Hammarosrroma albenense - laminar (2 specimens), domical Atelodietyon fallax - laminar



Arcloslroma contexlum - doi!1ical

215



Stromaropora parksi - domical Stromatopora cygnea - domical Pseudotrupetostroma n. sp. A - domical Lineastroma sp. A - domical Actinostroma papillosum - domical As in case 1, cases 2 and 3 demonstrate that more than one growth fonn occurs

together in the same environment; included is a mixture of species, some that show shape variability and some that do not. The species Hammatostroma albenense and

Trupetostroma papulosum are examples in case 2 of the fonner, both showing domical and laminar growth forms aI various localities (Table 4.1). Yet in this specific case they do not display the same growth fonn (i.e. one domical, the other laminar), as opposed to what would be expected if environmental influences controlled the shapes of these stromatoporoids. Case 3 is a similar example. Although dominated by domica! growth forms, laminar forms of the species Hammatostroma albenense and Atelodictyon Jallax are also included. If environmental factors were important in •.shap.ing the species "=:'-'

morphotype, ail specimens would be expected to show domical groV;th forms; they do not. Cases 2 and 3 show examples of the samespecies exlnoiting different growth fonns in the same environment. The species Aculatostroma ordinatum (case 2) shows both domical and bulbous growth forms occurring together; H. albenense (case 3) exhibits both laminar and domical growth forms. In both of these examples, it seems

e

216 unlikely that the environment was a major factor influencing the morphotype of these species. Interactions with Other Organisrns: Sorne Examples

Topsentopsis borings The sponge(?) boring Tops'!nJopsis has been observed in many Paieozoic stromatoporoids; a sirnilar boring has been observed in modern scleractinian corals (C.W. Stearn, pers. comm.). The boring consists of a central spheroidal cavity of variable size, with tubes or canals radiating from it which may be simple or branching.

Topsentopsis resembles modern borings produced by the bioeroding sponges C/iona and Aka. TopsenJoposfs borings are widespread in dornical, bulbous and rarely laminar stromatoporoids of the Cairn Formation (Figures 2.4B and 4.2). Sorne stromatoporoid specimens from the Grotto Member also exhibited these borings. The width of the central cavity ranges from 3 to 15 mm; the canals are 1-2 mm wide and may extend to the edge of the strornatoporoid skeleton (Figure 4.2). The boring structure shows no preference for any particular stromatoporoid skeletal element nor location within the skeleton. Of the 32 species identified in this study, 15 contain at least one Topsentopsis boring.

Most of these

species

of strornatoporoid are

stromatoporellids or

stromatoporids, and include Trupetostroma pycnostylotum. T. papulosum. T. warreni.

T. n. sp. A, Clathrocoilona crassitexta, Hennatostroma polymorphum. Arctostroma conJextum,

Stromaropora

sp.,

S.

parksi,

Salairella

cooperi,

S.

sp.

A,

Pseudotrupetostroma n. sp. A, Petridiostroma vesiculosum, P. n. sp. A, and

217

• Figure 4.2 A. Tangential section of Trupetostroma n. sp. A penetrated by Topsentopsis borings now filled with dark sediment. This example shows the rare occurrence of two central cavities of the boring being connected by a canal. Note the canals radiating from the central cavity reach the edge of the stromatoporoid skeleton. Sundance Range South, lower part of Upper Cairn Member; scale bar is 5 mm. B. Vertical section of Trupetostroma n. sp. A showing two main stages of growth, and encrusting a brachiopod. The specimen is penetrated by Topsentopsis borings now filled with dark sediment (middle-right and upper part of skeleton). The irregular boring on the right side is the result of the excavating of two central cavities side-byside, and subsequently overgrown by the second stage of stromatoporoid growth. This stromatoporoid specimen shows a low domical growth forro with ragged edges (left centre of photo). Mt. Bryant, lower part of Upper Cairn Member; scale bar is 5 mm.



219



k.:tinostroma papillosum. Since not every specimen that was found to comain Topsenropsis was idemified, it remains uncertain whether the sponge(?) organism that made the borings had any preference for particular species. There may have been more of a preference for strornatoporoids which grew with sorne considerable relief above the sea floor, such as high domical or bulbous fonns. The organisms dwelling in these bored cavities may have preferred to remain in contact with well-circulating seawater free of sediment, as suggested by sorne borings showing canals that extend to the surface of the stromatoporoid (Figure 4.2). No evidence was found to indicate the accomodation of stromatoporoid growth to the excavation of the canals, and it is not certain whether the stromatoporoid was alive or dead when these borings were made. Yang and Stearn (1990) described an ichnofossil fonned by an organism that preferentiaIly burrowed into the micritic sediment filling corallites of Ordovician tetradiids, but did not show any preference for certain species. Specimens representing aIl but one genera of tetradiid coral were found to contain these burrows, but not in every corallite. They attributed this behavior of the tracemaker to the attraction of organic matter that was preserved early inside the corallites from early fil1;ng of the corallites with sediment. The Topsentopsis cavities and canaIs rnay be filled completely with sediment or partiaIly filled to fonn geop~iaI structures. The sediment fill may be exclusively peloids, micrite, or rarely a mixture of both. Examination of the geopetal structures in toppled stromatoporoids show that many of the borings were infilled after the stromatoporoid skeleton had been moved. However, a few geopetal structures do

'.

:220



suggest that at least sorne borings were made and filled \Vith sediment while the stromatoporoid \Vas still in an upright position. and that the sediment was at least partially lithified before the stromatoporoid was re-transported. Pemberton et al. (1988) described Trypanites borings in IwO early Frasnian stromatoporoids from the Waterways Fonnation. one species overgrowing another. Erosion surfaces. the gro\Vth stages of the stromatoporoids, boring sediment fill. and geopetal structures of variable orientations indicate that the stromatoporoids were subjected to repeated penetrations during successive stages of growth and re-orientation. Table 4.2 Stratigraphie Occurrence of Topsentopsis within Stromatoporoids

Stromatoporoid Assemblage # of skeletons with Topsemopsis borings

FlumeMbr. 1 A B 2

8*

Upper Cairn Member C D 2

12

E

6

* ail 8 of these specimens were collected from the Upper Cairn pan of assemblage B. The stratigraphic distribution of Topsemopsis from field notes made during this study indicaœ a higher degree of boring activity within stromatoporoids during the deposition of the Upper Cairn Member compared tO the FIume Member of the Cairn Fonnation. These field observations are supported quantitatively from the exarnination of stromatoporoid specimens in thin section. Topsemopsis borings were observed in only 2 of a total of 42 (4.8%) specimens exarnined from the FIume interval; whereas



28 of a total of 110 (25%) were found within stromatoporoid specimens from the Upper Cairn Member. The number of specimens exhibiting Topsemopsis borings

221



within each stromatoporoid assemblage A to E (described in Chapter 3, part 2) are listed in Table 4.2. Assuming the number of Topsentopsis borings is a measure of bioerosion, boring activity increased during Cairn rime, and may be explained in terms of variations in energy conditions or nutrient supply. The change in depositional setting within the Cairn Formation from a broad carbonate platform during Fiume time to a carbonate ramp buildup geometry during Upper Cairn time probably resulted in a generally higher energy environment. Many Topsentopsis borings in the Upper Cairn Member are filled or partly filled with sand-sized peloidal grains exclusive of mud, at least indicating high energy conditions when the boring was infilled. In the modem environment, clionid boring sponges prefer very .:1J.allow, turbulent environments (Reimer and Keupp, 1991). The boring sponges(?) that made Topsentopsis may also have preferred shallow, agitated environments, explaining their increased occurrence in the Upper Cairn Member, but this interpretation does not explain the apparent lack of such borings in the high energy carbonate sand environments of the Peechee or Arcs members. However, it is important to note that the pervasive dolomitization of these units may have obliterated any evidence of Topsentopsis borings. Eutrophication promotes bioerosion, and the detrimental consequences of this relationship to modem carbonate buildups bas been demonstrated by Hallock (1988), Hallock and Schlager (1986), Wood (1993), and Edinger and Risk (1994). Severa! studies have shown that increased concentrations of nutrients and plankton in the carbonate environment stimulate bioerosion (e.g. boring bivalves - Highsmith, 1980;

.,.,.,



clionid sponges - Rose and Risk. 1984: cryptofaunal communities in general - Smith

el

al.. 1981) because many bioeroding organisms feed on components of the plankton in

both their larval and adult stages. Thus. the high boring activity during Upper Cairn lime may be related to increased nutrient supply in the water column. Evidence of bioerosion within stromatoporoid assemblages D and E (Table 4.2) suggest that this was a time of considerable nutrient influx: assemblage D coincides with a change l'rom a stromatoporoid to a coral biofacies in parts of Kananaskis Country and Banff National Park. Work published earlier as part of this study (Mallamo and Geldsetzer. 1991: Mallamo

el

al., 1993) suggested that the change in biofacies was also due to an increase

in the nutrient supply during Upper Cairn lime. This topic is discussed further ià Chapter 5.

Brachiopods and Corals Encrustation of brachiopods and corals by stromatoporoids is a common association in mid-Paleozoic reefs, and examples can be found in the Cairn Formation (Figures 4. lB, 4.2A, and 4.3A,B). Figure 4.1B shows an inleresting scenario in which an articulated brachiopod is preserved in living position within a stromatoporoid skeleton. The brachiopod larva must have anchored and initiated growth on the living stromatoporoid; the

{WO

organisrns co-existing for sorne considerable time before the

stromatoporoid encrusted and eventually overgrew the brachiopod. Geopetal sediment is preserved within the brachiopod shell but not within the stromatoporoid skeleton. During a period of increased sediment influx, the stromatoporoid probably "closed



.od aragonite cements. The Sr2+ content of fossils and cements are also discussed for the purposc of evaluating the significance of Sr2+ in constituents believed to have originally been LMC. HMC. and aragonite. Materials and Methods

Numerous fossi! specimen.; were analysed for Ca, Mg, Sr, Mn, and Fe with a Cameca Camebax electron microprobe at McGill. All specimens were collected from limestone strata at various localities, and include Paleozoic stromatoporoids, corals, molluscs, brachiopods, and calcareous algae, and Cenozoic scleractinian corals (described earlier). J'yf.any of the Paleozoic samples were collected by the author from Manitoulin Island, Alberta, and Quebec; sorne samples from Australia, France, Manitoulin ISland, Alberta, and Anticosti Island were"provided from the McGill University stromatoporoid collection in the Redpath Museum. The Pleistocene corals from Barbados described earlier were provided by E.W. Mountjoy from the collection ofN.P. James' Ph.D. study .





Results and Discussion The range of Sr2+ concentrations detected in aIl samples in this study are summarized in Table 4.5. Strontium vs. magnesian plots of various stromatoporoids and other fossils are shown in Figures 4.7 to 4.10 and Figure 4.12.

Stromaroporoids Average Sr2+ content of Silurian and Devonian stromatoporoids is bdow 1000 ppm (n=57), and Mg2+, below 7000 ppm (Table 4.5; Figure 4.7). Gallery cements analyzed in sorne of these stromatoporoids contain Sr2 + concentrations no greater than 460 ppm. The Fe2+ and Mn2+ concentratio.lS of these stromatoporoid skeletons were below 500 ppm. These trace element concentrations closely match those values oetected . in Late Devonian marine LMC cements and brachiopods from the subsurface of Alberta and from the Canning Basin in Australia (Carpenter et al., 1991). In a Devonian stromatoporoid skeleton interpreted to be originally HMC, Rush and {iiafetz (1991) detected Sr2+ concentrations of 1380 ppm (three spot analyses), and 1140 ppm of Sr2 + in gallery cements (two analyses); Mg2+ concentrations of 2160 ppm were detected in the same three analyses of the stromatoporoid skeleton. These trace element values are within the range detected in LMC and considering the few spot analyses, add little value to the interpretation of original skeletal mineraiogy. Middle and Late Ordovician labechiid stromatoporoids in this study show considerably higher Sr2+ concentrations, ranging from 40 to 3620 ppm (n= 129; Table 4.5; Figures 4.8 and 4.9A). Most analyses detected Mg2+ concentrations below 9000



ppm. The wide range of Sr2+ concentrations reflects the variable degree of diagenetic

245



TABLE 4.5 Description of Samples and the Ranges of their Sr2+ Contents SAMPLE# RBD3 SD-l PM:3 STYLO 89-9-14-2 KB 72-169-1J 95-14 AULO 97-1 97-3 LAB·I MAN lb MAN Ic MAN Ig

'c, MAN Ij MAN2a MAN2d MAN2i

MAN4e

Tet 2

Sr-+ (ppm) SPECIMEN Acropora palmi11a 1340-10000 800-2280 ·aragonite & calcite cements Acropora cenlicomis 2690-3600 170-2040 ·aragonite & calcite cements 190-1500 Porites sp. Srylostroma sp. 0-840 Trupetostromo. papulosum 0-340 -gallery cement 0-460 Acularosrromo. stel/iferum 100-920 -gallery cement 0-290 0-790 Clathrodictyid -gallery cement 0-380 Aulacera 40-1340 -gallery cement 0-:'.$0 Labechiid 170'1760 -gallery cement 0-210 Labechiid 140-2210 -gallery cement 0-290 Stroml11ocerium sp. 450-2080 180-3620 Srroml11ocerium sp. -gallery cement 240-800 480-900 Brachiopod Gastropod 100-890 630-1340 Brachiopod 950-1820 Ostracode 240-1:70 Echinoderm Rugose coral 620-790 330-550 -cement within skeleton Dasyclad algae 120-1490 Bivalve - weil preserved pan 1250-1970 - altered pan of sbell 670.760 CaIapoecia (tabulate coral) 390-1410 -cement within skeleton 0-690 Labechiid 50-1240 670-1330 Brachiopod -cement 410-780 Gastropod 240-360 Ostracode 930-3250 Rhalidotetradium gigameum 100 - 2920 (tetradiid coral) Ostracode 2360-2850 -internal cement 470-2150 Micrite 380-640. Rhahdoterrad!'9n gigameum 330-2130 -internai cement 100-850

AGE and LOCATION Pleistocene. Barbados " " "

Miocene. France Fameanian. Alber : - Frasnian. Alberta " "

"

Ludlovian, Australia "

Late Ordovican. Anticosti Island Middle Ordo\ician, Manitoulin Island "

" "

Late Ordovician, Manitou1in Island " "

-.

"

" " " " " " " " " " " " "

~.

"

Middle Ordovician, Manitoulin Island " " " " "

.

246

• Figure 4.7. Sr vs. Mg concentrations of Silurian and Devonian srromatoporoids from various localities (see Table 4.5), including the Famennian labechiid Srylosrroma sp.. Nore that the Sr2+ content of these specimens does not exceed 1000 ppm, and the similar Sr2+ values of the skeletons and gallery cements. The species Trllpetostroma

papulosum and Aculatostroma stelliferum are Frasnian srromatoporoids collected from the southern Canadian Rock)' Mountains.

-,

-:',



• Silurian and Devonian Stromatoporoids 1800 1600 1400 1200 ~

E

a. a.

-.

1000 0

li)

800

...

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+ 0

600

o + 0

0

Â

400 Â



200 0

• • 0

0

2000

.0

••

0

0

0

0

0 1

6000

4000

1

8000

Mg (ppm) Â

7h/petostroma papllloslIIlI

o

StylostrOlI/(/

o

AClllatostroma stel/iferlllll

+

Clalhrodiclyid

s)J.

• gallery cemenls

1

10000

248

• Figure 4.8. Sr vs. Mg concentrations of Ordovician labechiids and their cements. A. Labechiid (Labechia? sp.; sarnple 97-1) of the Middle Ordovician Lindsay Formation, Manitoulin Island, illustrated

'1

Figure 4.6 A.

B. The labechiid Aulacera sp. (sarnple AULO) from the Upper Ordovician of Anticosti Island, and another labechiid (Labechia? sp.; sarnple 97-3) of the Lindsay Formation from Manitoulin Island. Note the consistently low Sr2+ content of the gallery cements compared to the labechiid skeletons, and the lack of correlation between Sr and Mg.

Ordovician Labechiids 2400 2200

(sample 97-1)

1-

2000 1800 1-

0

1600 1-

Êc.

~4OO

0

.e

1200 l-

CIl

1000 1-

-

a

0

0

0

0

0

800

00

0

400

200



,pO

600

-





A

~O

0

2000

0

0

0

.0

• 0

0

0

. 4000

6000

10000

8000

Mg (ppm)

o skeleton

14000

12000

• cement

2400

o

2200

2000

1-

1800 11800 1-

Ê c. S:

-

CIl

1400

+

1200

+

+

o 00

o

o

1000

000

800

1-

.j' + +

o

400

0

0000'0

• +'_"

200

rte

o 0 oq,o::l!1\ 0 o 00

800 1-

CD



D

OI~_"'.:!:+:""":+"''::''-'-_--L._....1._---L_':·:..L-

o Aulacera

B r (Late Ordovlclanl

2000

4000

+ skeletoxil • cement

1

6000

Mg (ppm)

sooo

....1._......l---J 10000

r Labecbiid (97-3) [MIddle Ordovlclan)

oskeleton • cement

250

• Figure 4.9. A. Sr vs. Mg concentraùons of {wo different specimens of Stromatocerium sp. of the Meaford Member of the Georgian Bay Formaùon from Manitoulin Island (LAB-I), and of Upper Black River Group near Joliene. Quebec. (MAN lb). The highest Sr2+ concentraùon (3620 ppm) within a stromatoporoid was detected from sample MAN lb. B. Sr vs. Mg concentrations of panly calcitized aragonitic sponges (Upper Permian. soutnern Tunisia). Sponges with a relatively high percentage of aragonite still preserved conrain the highest concentrations of Sr2+. Note the low Sr2 + values (ranging from 265 - 2325 ppm) for those sponge skeletons which contain less than three percent aragonite, and compare with those Sr2+ values detected in

Strornarocerium sp. shown in A above. Data from Scherer (1986) .

. -'

.

_,'r



Stromatoceriwn Sp.

Ordovician

4000

"

3500

3000

(Mg = 21780 ppm)

-

"

2500 ~

Ê

c.

.

.B:

"

"

2000



••

" .~ • • "" • • • " • • • A"" S, • " • • • "" •• • "A A " ".

·

U)

1500

CI

1000 ~ 500 ~

0

CI "

2000

4000

6000

BOOO

10000

12000

Mg (ppm)

• sampJe LAB-I (Middle Ordovician) " sample MAN lb (Late Ordovician) A gallery cernent of sample MAN lb

A

Aragonitic sponges

laIe Permisn,

5000

.44

.33

4500 4000 ~

.16

3500 ~

-

3000 ~

.B:

2500 ~

U)

2000

l-

1500

l-

E c.

.

• 31

';0 .10

." ri>

.9

..p

l-

C

c

CI

500

l-

c"

"

c

c

ra .'5

.'9

"

'\0

"

s."

c 2Clo

.

.40

.10

10 1000

29.

40• •31

.'5

cCc"

"

Dc

"

C

Cc 9

'0.

0 2000

4000

6000

8000

Mg (ppm)

B

• ,.percentage of ske1eton still aragonite "ca1citized ske1eton with Jess than 3 percent aragonite (dat:>. alter Scherer. 1986)



alteration in these samples. Sr2+ concentrations above 1500 ppm \Vere delecteù in 16 analyses. most of which were found in the two specimens (both SlrOIllQlocerill1ll sp.; Figure 4.9A). The Late Ordovician specimen of this species (sample MAN 1b) l'rom Manitoulin Island contains the highest single Sr2 + and Mg2+ values deteeteù: 3620 ppm and 21780 ppm. respectively. The Sr2 + contents of the gallery cements are much lower than those of the skeletons; most values are below 300 ppm but as high as 800 ppm. However. it is worth noting that the two highest values detected in gallery cements (800 and 460 ppm; sample MAN lb) were from those cements containing specks. which are interpreted to be remmu,,:; of syntaxial aragonite cements. A spot analysis of the labechiid eysl irnmediately adjacent to the cements containing the specks detected 1800 ppm of Sr2 +; the clear gallery cement with no specks directly above the cyst contained only 240 ppm of Sr2+. The high Sr2+ content (> 1500 ppm) of the Ordovieian labechiids are comparable to those values detected in corals and sponges of known aragonilic skeletal mineralogy, suggesting that the labechiids may have originally secreted an aragonite skeleton. Similar Sr2+ contents were detected from the calcitized aragonite skelelons of the scleractinian corals ACTopara pa/mata (range 1340 - 10,000 ppm; average 2705 ±882 ppm). A. cervicarnis (range 2690 - 3600 ppm; average 3085 ±308 ppm). and Parites sp. (range 190 - 1500 ppm; average 770 ±389 ppa';Sè;:"Figure 4.5). "~

Pleistocene corals reported by Pingitore (1976) contain



in

phr~tic-

averag/~s

"~

of 1300 and 2G50 ppm .

and vadose-altered specimens, respective!y;c(fable 4.4). Permian and

253 Triassic aragonitic sponges (Scherer, 1986; Veizer and Wendt, 1976) contain a range of Sr2 + values comparable to the high Sr2 + values of the Ordovician labechiids (Table

4,·,;,

The Permian sponges with 3% or less primary aragonite still preserved contain

ooly 265 - 2325 ppm of Sr2 + (Figure 4,9B; Scherer, 1986), A Late Triassic aragonitic sclerosponge, Aetinofungia astroiIes. from the Cassian Beds in Italy contains 1320 ppm of SrH (Veizer and Wendt, 1976), Sorne Recent HMC skeletons of marine animals contain Sr2+ contents up to 2640 ppm, and red algae up to 2960 ppm (Table 4.3). These values overlap with the Sr2+ content of the Ordovician labechiids, and ma)' suggest that the labechiids originally secreted HMC. If this interpretation is correct, it would imply that the Ordov:cian stromatoporoids have retained their original Sr2 + content and experienced little or no alteration contrary to their present state of presen·ation. Furthermore, the Sr2+ values over 3000 ppm detected in Stromatocerium sp, (F:gure 4,9A) exceed the highest values of HMC marine organisms, thus suggesting a skeletal aragonite rather than HMC precursor. Devonian stromatoporoids interpreted to be originally HMC by Rush and Chafetz (1991) contain lower Sr2+ contents of 1380 ppm. Stearn (1989) noted that post-Ordovician labechiids and other stromatoporoid orders were better preserved and speculated that they may have been originally calcitic skeletons.- The Sr2+ data in this study is in agreement with this conclusion,

è!Jmparisons with Other Fossils The Sr2+ content of other fo~sils associated with the Ordovician labechiids from



Manitoulin Island are summarized in Table 4.5. The skeletons of the Middle

254

Ordovician tetradiid coral RhabdoteIradillm giganrellm are completely recrystallized preserving no original skeletal fabric. but ponions contain high Sr2+ concentrations up to 2920 ppm (n = 53). These are high concentrations in comparison to the low Sr2+ contents (100 - 850 ppm: n=4) of the cements within the corallites. The high Sr2 + contents are similar to those of caicitized aragonite corals and sponges described earlier. and suggest that the original mineraiogy of these tetradiids \Vas aragonite. The Manitoulin molluscs show variable degrees of preservation and Sr"+ content (Table 4.5), but they were probably originally aragonitic also. In the weil preserved parts of a bivalve that display fine growth lines, a specimen contains relatively high Sr" + concentrations up to 1970 ppm (n=7), values comparable to sorne modern and ancient aragonite bivalves (Bathurst, 1975: Sandberg and Hudson. 1983: compilation of data in Brand and Morrison, 1987: Table 4.3). Low Sr2+ values of 670 ppm and 760 ppm were detected in the more coarsely

recrys!~;r:~ed

parts of the shell. In a gastropod shell

preserved as a coarse mosaic of neomorphic spar similar to that of the tetradiid corals, low Sr2+ concentrations ranging from 100 ppm to 890 ppm were detected (n=8). The spar-ftlled mold of the gastropod suggests that the shell was originally aragonitic, but this interpretation cannot be supponed by the Sr2+ content. Sr2+ concentrations not greater than 1410 ppm were deœcted in this study fr0m skeletons and shells (and their associated cements) believed to have been originally LMC (brachiopods, corals?), and HMC (echinodenns), with the exception of L'le ostracodes (Table 4.5). Manitoulin ostracode specimens contain significantly higher



Sr2+ concentrations than the other calcitic-secreting animais, ranging from 930 to 3250

","

255



ppm (n= 14). In one sample of calcite cement completely filling the inside oi an aniculated carapace (MAN 4e). one high Sr2 + value \Vas detected (range 470 te 2150 ppm, n=4). Crustaceans as a group are known to contain high Sr2+ concentrations in their calcitic carapace. up te 5500 ppm (compilaùon of data in Carpenter and Lohmann. 1992); Sr2+ concentrations ranging from 2800 to 3700 ppm \Vere reported in Holocene ostracodes by Burke and Bischoff (1989). The elevated Sr2 + content of ostracodes and other crustaceans have been attributed te very rapid rates of calcite precipitation (Carpenter and Lohmann, 1992). a result from the molting and re-growth of û'leir exoskeletons (Burke and Bischoff, 1989; Lowenstam and Weiner, 1989). Thus. the high Sr2 + content of the Manitoulin ostracodes is interpreted as a indication of rapidly precipitated carapaces of LMC calcite rather than aragonite mineralogy. To summarize, the Sr2+ values detected in various Ordovician fossils are values expected to be found in each fossil type. and indicate that at least sorne of these fossils have retained much of their primary trace element contents.

Interpretation of Sr - Mg Diagenetic Trends Although the Sr2+ values of the 1abechiids (and tetradiids) have a wide range, the highest values (such as 3620 or 2920 ppm) are considered the most meaningful, and are comparable to other calcitized aragonite skeletons (Tables 4.4 and 4.5). Because of the large size of the Sr2+ ion, the original Sr2+ ions of the aragonite crystal are not easily incorporated into the newly precipitating calcite crystal during the aragonite-tocalcite transformation. This usually results in a decrease in Sr2+ content in the diagenetic calcite, as illustrated by the Acropora palmata analysis (Figure 4.5) in this

256



sntdy and other srudies discussed earlier. Decreasing 5r2+ content during diagenesis implies that the 5r2+ content detected in Ordovician labechiids and tetradiids is the 5r2 + retained from the original aragonite precursor. and was not later introduced diagenetically into the skeleton. This interpretation is corroborated by the low 5r2+ content of associated gallery cements. The higher labechiid and tetradiid 5r2+ values are thought to be "elevated" (sensu 5andberg, 1985) since they are above levels reasonable for primary calcites and recent high-Mg calcite skeletons. Both tetradiid samples analysed in this srudy show a diagenetic trend in which the concentrations of 5r2+ and Mg2+ are inversely related. A similar trend is shown in the ·Pleistocene corals analysed in this srudy (Figure 4.5) and in srudies of aragonite diagenesis by Veizer and Wendt (1976), Brand and Morrison (1987), 'and Brand (1989). Conversely, the diagenetic trend of calcitic constiruents show a positive correlation between 5r2 + and Mg2+ contents; with progressive diagenesis, both trace elements decrease (Brand and Morrison, 1987). In this srudy, this diagenetic trend of cakites is best displayed by the ostracodes. If evident, the distinct aragonite and calcite diagenetic trends could contribute to the interpretation of the original mineralogy of ancient dLMC. Unforrunately, the 5r2+ and Mg2+ data for strornatoporoids collected in this srudy and the Late Permian aragonitic sponges from Tunisia (Figure 4.9B) show no diagenetic trends or correlation; their interpreted aragonitic precursor is mainly based on elevated 5r2+ content.

257



Biomineralization and Secular Variations in CaCO) Mineralogy The growing lines of texmral and biogeochemical evidence inlply that stromatoporoids may have originally secreted an aragonitic skeleton during the Ordovician. and an HMC skeleton during Siiurian and Devonian times. An expianation for the change in stromatoporoid skeletal mineralogy must account for two possibilities: that stromatoporoid biomineralization flucmated with environmental conditions. i.e. was influenced by external factors (sensu

"bioinduced" biomineralization

0:--

Lownenstam and Weiner. 1989); or conversely. stromatoporoid biominera!ization was biologically controlled. independant of ambient conditions. as demonstrated by freshwater calcite-secreting molluscs. Environmenta! conditions such as temperature and perhaps salinity can cause the flucmation of aragonite and calcite precipitation in sorne corals. molluscs. bryozoans. worm mbes. and barnac!es (Lowenstam and Weiner. 1989). The possibility that an evolutionary change occurred in the biominera!ization of stromatoporoids during the early Paleozoic may be considered too simplistic. as ,

:-

suggested by Stearn (1989). Alternatively. Stearn (1989) and Kershaw (1994) have suggested bioinduced biomineralization as a possibility. in that the geochemistry of marine waters changed near the end of the Ordovician. Sandberg (1983) documentcd an oscillating Phanerozoic temporal trend in abiotic aragonite/calcite mineralogy. which Wood (1991a) believes may have had an underlying control on sponge mineralogy. Wendt (1984) noted that the mineralogic composition of non-spicular calcareous



sponges changed through time. from aragonite to HMC in the Jurassic to ear!y

258



Cretaceous,

:l

time coincident with a change from "aragonite to calcite seas" on

Sandberg's (1983) carbonate curve. Although the end of the Ordovician time falls within an "aragonite-inhibiting" episode of non-skeletal carbonates, Sandberg (1983: p. 22) notes that his oscillating trend "reflects oniy inferred first-order changes in non-skeletal carbonate mineralogy. It is possible that second-order oscillations could have resulted in short-term aragonitefacilitating conditions in an otberwise primarily aragonite-inhibiting episode, or vise versa.". A second-order change in carbonate mineralogy may have briefly occurred near the end of the Ordovician, affecting stromatoporoid biomineralization. The Late Ordovician was a time of glaciation during which global temperarures must have lowered, even in sub-tropical latirudes. Temperarure has been shown experimentally by Burton and Walter (1987) to be a major control of carbOnate mineralogy, more important than pC02' the saruration state of

col-,

and Mg/Ca ratios. Lower water

temperarures (5 oC) favor the inorganic precipitation of calcite, whereas at higher water temperarures aragonite becomes dominant over calcite. If stromatoporoid biomineralization was bioinduced rather than biocontrolled, then lower ambient temperarures during the Late Ordovician may have triggered a permanent change in stromatoporoid skeletal mineralogy to calcite, just prior to the rapid diversiry of the group in the early Silurian.

Summary Ordovician labechiids and tetradiids preserved as dLMC COntain Sr2+



concentrations comparable to the Sr2+ content of known calcitized aragonite skeletons, and higher than primary LMC and HMC constiruents. Tetradiid corals are preserved as

259



a coarse mosaic of neomorphic spar showing no original ske1etal microstructures. and a Sr - Mg diagenetic trend indicative of aragonite diagenesis. Ordovician lar..:chiid stromatoporoids show ghosts of syntaxial aragonite cements and skeletal

Sr~ +

conCt:ntrations up to 3620 ppm. Conversely. Silurian and Devonian stromatoporoids display bener preservation (even the labechiids). sorne have been shown to contain microdolomite. and conrain considerably lower Sr2 ... concentrations similar to other calcitic skeletons. The observed temporal change in stromatoporoid skeletal mineralogy may reflect bioinduced biomineralization. This new geochemical evidence corrohoratcs previous texturaI evidence. confirming that these O..dovician stromatoporoids and tetradiid corals secreted aragonite skeletons.



260



PART 3: THE ROLE OF PHOTOSYMBIOSIS IN STROMATOPOROID GROWTH AND EVOLUTION

Introduction In modern reefs, the main framebuilders are the scleractinian corals. These corals have a symbiotic association with algae (dinoflagellates), which may contribute to higher ratcs of calcification and increased skeletai growth rates (Swart, 1983; Constantz, 1986). Coral-algal symbiosis is one of the major reasons for the dominant position of the scleractinians in the reef community (Stanley, 1981). In addressing the possibility that fossi! metazoans contained symbionts, workers have briefly mentioned the probabi!ity that stromatoporoids had symbionts, but no evidence is provided (Coates and Jackson, 1987; Talent, 1988; Wood et al., 1992; Wood, 1993; Kershaw, 1993). Cowen (1983; 1988) provided the most extensive list of criteria for the inference of symbiotic algae in the fossi! record. Stromatoporoids and other invertebrates were included in a figure (Cowen, 1988, his figure 2) showing the application of criteria for testing for photosymbiosis (see Table 4.6 in this study); although stromatoporoids were not discussed, he tentatively concludes that they, and ail Phanerozoic reef builders probably were photosymbiotic. Wood (1993) also suggested the possibility that Paleozoic stromatoporoids were hosts to photosymbionts, but that



there

are

unpublished

prelirninary

carbon

isotope

results

~dds

(at

261

Table 4.6. Application of criteria for testing for photosymbiosis. comparing selected reef building and reef dwelling organisms (modified from Cowan. 1988). The asterisk (*) denotes criteria not previously tested lIccording to Cowan (1988), but tested in this

study,

-

• Table 4.6

CRITERIA

Stromatoporoids Scleraclinians Archeocyalhids

EXPOSED TISSUE yes H1GHCaCOJ yes I3QDY SIZE OR yes GROWTHRATE "THIN TISSUE yes SYNDROME" "AI3ERRANT NA MORPHOLOGY" ISOTOPIC probably (*) ANOMALY I310GEOGRAPHY yes (*) DEPTH AND yes HAI31TAT OLlGOTROPHtC probably (*) SUCCESS (*) lested in Ihis sludy

Rudisl bivalves yes yes yes

Rligose corals

Tablilale corals

y"s yes nol lested

larger Foraminifcra ycs yes yes

yes yes yes

yes yes

yes

yes

yes

yes

yes yes probably (Meyer, 1981) yes

NA

NA

yes

NA

NA

yes

yes(?)

nol lesled

nol lested

nol lesled

nol tesied

yes

yes yes

yes yes

yes yes

nol lested probably

probably probably

yes yes

ycs

1I01lcsted

probably

not Icsted

1101 tesied

yes

yes

~63



the University of Liverpool) which show no algal fractionation. Unforlunatdy. Wooù (1993) does not provide any isotopic data. In this section. 1 plan to review criteria used to infer algal symhiosis (also tenned photosymbiosis) in the fossil record. and test the hypothesis that at \cast some Paleozoic stromatoporoids hosted photosymbioms. In addition to evaluating the criteria listed by Cowen (1983; 1988). new evidence will be presented. including preliminary stable isotope data.

Algal Symbiosis Goff (1983) explained that symbiosis (sym. together; biosis. living) was a tcrm first used by deBary (1879) to describe the intimate interactions of dissimilarly named organisms,

including ail degrees of parasitism. as weil as mutualistic and

commensalistic associations. Successful symbiotic associations are fonned by numerous autotrophic a1gae (including green algae, and dinoflagellates) and cyanobacteria (bluegreen algae) with animal, plant, and fungal hosts (usllally simple heterotrophs). These associations can he extracellular or intracellular. As symbionts, the alga' s morphology is altered, as is its biochemical and physiological activity, notably by the loss of capabilities to live independently (Goff, 1983). The host-algal symbiotic system was termed simply mixotrophic by Hallock (1982), where a mixotroph is an organism that . both feeds and photosynthesizes, thereby imemally recycling nutrients. Pardy (1983) introduced the tenn phycozoan to "denote the compound organism resulting l'rom the intimate association of algae and animais." Preference is here given to the term



mixotroph because of the common usage of the tenns autotroph and heterotroph.

264



Advantages and Disadvantages Why would two dissimilar organisms form an intimate interaction within a community? Hallock (1981; 1982) has offered a powerful and workable model outlining the advantages of algal symbiosis. She demonstrated mathematically the energetic advantage of algal symbiosis to both the host and alga under extremely nutrient deficient (oligotrophic) conditions. Under these conditions, difficulties naturally exist for both invertebrates and algal cells in their search for food. The limits on algal growth are determined by the availabiliry of nutrients (nitrogen and phosphorus) when light is not a limiting factor (Hallock, 1981). The major cnncentration of nutrients is found in living organisms or organic detritus (Hallock, 1982). Thus, by living on or within an animal, algal cells are provided with a continuous supply of nutrients from the animal' s metabolic wastes. The host also provides protection for algal cells. This is especially important during times of scarce nutrients because it may take a long time for an algal cell to reproduce itself, and without protection, the cell risks the chance of being eaten or washed into an unfavorable environment before being able to reproduce (Hallock, 1982). Similarily, animais must expend large amounts of energy to capture food when inorganic nutrients are rare because particulate organic matter is scarce. But if they contained symbiotic algae, the algal cells can release sorne of the organic matter they ftx (as photosynthate) back to the host, and the host has an extra source of organic material for respiration a'ld growth (Hallock. 1982). The host's energetic advantage in a symbiotic association



may be utilized to grow skeletons thicker, stronger, and faster (e.g. Foraminifera,

265



corals), which prompted Talent (1988) to describe these animaIs as "solar-powen:d" metazoans. Disadvantages of algal symbiosis arise during nutrient-rich (cutrophic) conditions (Hallock, 1982; Hallock and Schlager. 1986). They include the following: (1) Competition for space. Free-living algae can rapidly reproduce themsclves in eutrophie environmenlS, whieh means abundant food is available for animaIs. Animais that could take advantage of an abundant food supply are those able to rapidly grow and reproduce themselves (Le. r-selected species such as echinoderms, and barnacles; see page 369 ). This group would outcompete slower-maturing. highly specialized Kselected species (mixotrophic corals) for space, especially in the early stages of a benthic community. A modern example exists off the west coast of Panama (Birkeland. 1977); (2) Habitat destruction. A reef community built by mixotrophic corals is undcr the risk of drowning if relative sea leve! is rising and bioerosion exceeds accretion of rcef framework, because large populations of reef-dwelling bioeroding organisms thrive in eutrophie conditions (Hallock, 1988); (3) Biotic disruption. Hallock and Schlager (1986) reviewed studies which showed the harmful effeclS of eutrophieation on mixotrophic (or hermatypic) corals. Corals will secrete more mucus than they can shed, and therefore are subject to damage by bacterial blooms. Coupled with bioerosion, eutrophic conditions also promote the dominance of mixotrophic corals by fleshy macroalgae. And lastly. eutrophication



promotes planktonic blooms which increase turbidity and cut out the amount of sunlight

266



rcaching the mixotrophic corals and their symbiotic algae. This is described in more dctail in Chapter 5. Modern Coral-algal Symbiosis Dinoflagellates, widely recognized as symbionts, have emerged as a strong biogeochemical force. helping to structure and stablilize shallow water rropical marine ccosystems (Taylor, 1983); perhaps the best-known example is the modern coral reef ecosystcm. The coral-algal symbiosis is briefly reviewed here because corals and stromatoporoids had similar growth and habitats. ln the coral-algal symbiotic association. the dinof1agellates inhabit the cndodermic tissue of the sderactinian coral (specifically, the gasrrodermic area of the endoderm); and are cornmoniy referred to as "zooxanthellae". However. Taylor (1983) suggests that "zooxantheIlae" should be avoided for two reasons; (1) there are taxonomie discrepancies concerning the genus Zooxanrhella; and (2) the most cornmon dinoflagellate species recognized in associations involving corals is not a species of

Zooxanrhella. but Gymnodinium microadriaticum. The terms hermatypic and ahermatypic were proposed by Wells (1933, p. 27); "The term hermatypic, from herma, a reef, is therefore proposed to describe corals of the reef-building type, the living species of which possess symbiotic zooxanthellae within thin tissues." Since then, there has been a great deal of research concerning corals with and without symbiotic algae (see review by Stanley and Cairns, 1988), and we have a dearer understanding of the various modem reef-buildups and reef-builders,



and of the coral-algal symbiotic association. Various workers have reviewed the

267



ambiguities of the terms hermatypic and ahemlatypic (Stanley. 1981: Stanley anù Cairns. 1988: Schuhmacher and Zibrowius. 1985). Confusion is

cre~ . teù

when applying

this terminology since dinoflagellate symbionts are never preserveù in the fossilizeù hosto Stanley (1981. p. 509) proposed that "their usage be restricted tl' inùicate observed or inferred presence or absence of zooxanthellae. The assignment of any fossi! coral to one of the categories should not be based wholly on whether they oceur in reef associations but rather on a variety of direct and indirect criteria." Schuhmacher and Zibrowius (1985) attempted to solve the ambiguity by modifying Wells' (1933) original definition. suggesting that the tcrms hemlatypic and ahemmtypic denote the contribution to framework in classic shallow-water rcds. They proposed additional terms: (i) "constructional" and "non-constructional" refer to the formation of durable structures with or without topographic relief in cither shallow or decp water; (ii) "zooxanthellate" and "azooxanthellate" refer to corals with or without symbiotic associations with algae. 1 agree with Stanley's (1981) statement that caution should be exercised in the usage of herrnatypic, but the original definition by Wells (1933) specifies a reef-building type of coral. The modification of thesc terms that "have gained wide usage and may appear to most casual readers as rather straightforward and unequivocal in application" (Stanley and Cairns, 1988, p. 234) couId add more confusion. The redefinition of the terms hermatypic and ahermatypic by Schuhmacher and Zibrowius (1985) does not seem useful. The terms "constructional" and "nonconstructional" seem to have more practical applications. but "zooxamhellate" and



"azooxanthellate" must be avoided for reasons explained earlier. 1 propose that the

268



tcrms hermatypic and ahermatypic only be used in their strictest sense as originally dcfined by Wells (1933); in other words. hermatypic corals are those living coral species known to build reefs and contain symbiotic dinoflagellates within their tissues. To replace "zooxanthellate", 1 prefer the useful and simple term. mixotroph, described earlier. Mixotroph can be used to describe corals, or any other invertebrate observed or inferred to host a symb.otic association with a1gae. The "shallow-water" modifier is not needed since algal sy.nbioses are generally restricted to areas of shallow water, and the inference in the fossil record requires that shallow water be a criterion. Thus. a coral that contains symbiotic algae and builds "classic" shallow-water reefs is described simply as a constructional mixotrophic coral. A coral observed or inferred not to contain symbiotic algae could be described as heterotrophic or non-mixotrophic, but a water depth modifier may be needed since these types of corals live in water depths From 0 - 6200 m (Stanley and Cairns, 1988).

Symbiont-enhanced Skeletogenesis Various theories that the symbiotic dinoflagellates within modem coral tissues play a role in the rapid calcification of mixotrophic coral skeletons have been proposed, and have been reviewed extensively (Swart, 1983; Cowen, 1983; Constanti,. 1986). Basic theories on the effect of algal symbiosis on calcification include; those that suggest the removal of metabolic products From the site of CaC03 deposition; and those that consider the translocation of carbon fIXed photosynthetically to the animal (Taylor, 1983). The simplest and widely recognized theory by Goreau (1959) proposed



that the dinoflagellate symbionts increased the rate of skeleton formation by removing

269



C02 during pholOsymhesis. shifting the carbonate equilibrium and favouring the precipitation of CaC03. Constantz (1986) and others have pointed out that these mechanisms fail to explain the rapid calcification rates at the tips of branching corals where the tissue is apparemly depleted of symbiotic algae. or the fact that some heterotrophic corals have comparable skeletal growth rates to other mixotrophic corals. An alternative explanation of rapid calcification to the symbiont-enhanced theory is that the construction of the scleractinian coral skeleton may be a predominantly physiochemical process taking place in a thin film between the aragonitic skeleton and the soft tissue (Constantz. 1986). However, physiochemical crystal growth of aragonite is limited inseawater by the availability of C032-. Thereforc, the rate of crystal growth may still be increased by the local removal of C02 during photosynthesis since this leads to an increase in C032- activity within the coral's tissues (Constantz, 1986). Stromatoporoid Photosymbiosis Criteriit.for Testing Symbiosis in the Fossil Record '-

Direct evidence of symbiosis (the discovery of the algal symbioms themselves) is highly unlikely in the fossi! record (Stanley, 1981; Cowen, 1988; Talent, 1988). Kershaw (1993; and numerous other studies) had described symbiotic associations of stromalOporoids and syringoporid tabulates in reefal and non-reefal settings. Kershaw (1993) speculates with caution that this association may be a reponse to decreased nutrient

supply.

Kazmierczak

(1971)

suggested

that

astrorhizal

canals

in

stromatoporoids are not excurrent canals but actually traces of a symbiotic organism;



this view is not commonly supported (see discussion by Stearn, 1975). Thus, ;n order to prove the presence of a former symbiont, one must provide indirect criteria of

270



photosymbiosis. "Symbiosis is such a fundamental aspect of biology that it imposes specific characters on symbiotic organisms. In sorne cases those characters are so noteworthy that they may be used to infer algal symbiosis in the fossil record" (Cowen, 1983. p. 439). It is worth noting that even if direct evidence of a photosynthetic symbiont was discovered within a host. mixotrophism would still be uncertain. Many Caribbean coral reef sponges contain cyanobacterial symbionts within their tissues. but do not derive any nutrition from this association (Wilkinson, 1987); this modern relationship is described in more detail in the Discussion section. Usable indirect criteria (Cowen, 1983; 1988; Table 1) include: (1) exposed, thin tissue; (2) body size. and high calcification and growth rate; (3) isotopic data; (4) biogeography, habitat, and depth; (5) oligorrophic success; (6) evolutionary patterns; and (7) aberrant morphology. These criteria are subdivided into two categories: (A) those which are prerequisites and promote symbiosis; and (E) those which result from symbiosis. Category A: Prerequisites of Symbiosis 1. Exposed.

Thin Tissue.

Srromatoporoids have a body plan that favours

photosymbiosis. Stearn (1975) and Stearn and Pickett (1993) Ïnterpreted exposed soft tissue (approximately 1-2 mm thick) to be resrricted to the top tiers of the stromatoporoid skeleton. Srromatoporoid growth pattern may be described as photorropic; many species grew upward (and outward) from a single point where the larva settled. in contrast to a cryptic growth habit. Their growth pattern is evident even ,



from the earliest ontogenetic stages, when algal symbiosis would have contributed to

~71



the rapid growth and calcification beneficial for juvenile stromatoporoids. However. photatropism may be confused with geotropism: the upward growth pattern is common ta ail benthic animaIs that grow up away from the sediment to effective!y sample the water column. But, like many metazoans. the stromatoporoid's growth pattern wou!d still have been preadaptive for algal symbiosis. Sorne workers have noted an increased population of laminar stromatoporoid growth forms in rocks interpreted ta be deposited in deeper reef slope environments. in comparison to those of backreef or lagoon environments. Perhaps these stromatoporoid species were responding to lower light conditions in a manner similar to that of modern scleractinian corals (Graus and Macintyre, 1989). Their shape could also retlect the lower sedimentation rates in slope settings, or both intluences. The thin tissue of stromatoporoids would have been beneficial for algal symbiosis. Active nutrient uptake by symbionts from seawater will only be effective close to the stromatoporoid 's surficial tissue. A thin tissue anatomy would enable algal symbionts to live close to the site of skeleton secretion (pinacoderm in sorne stromatoporoids) at the base of the soft tissue and still allow the uptake of nutrients. Category B: Results of Symbiosis

2. High Calcification. High rates of calcification in symbiotic hosts are expressed as rapid growth of skeleton, large size, and a high skeleton-to-body ratio, or any combination of these (Cowen, 1983). Exact growth rates of stromatoporoids are relatively unknown, but many workers have speculated that they were rapidly growing



metazoans (Kershaw, 1993; Wood et al., 1992; Fagerstrom, 1983), especially in a

272



lateral direction. Meyer (1981) anempted to calculate and compare the relative and absolute growth rates of stromataporoids and tabulate corals. Assuming that the coral's rhythmic changes were annual. he determined that the favositid coral's vertical growth rates were 7.9 to 11 mm per year. while the stromataporoids grew vertically at rates of 1.3 to 3 mm per year and laterally at rates of 10.4 ta 23.1 mm per year. Although his assumption about annual layering in corals makes these absolute values conjectural. Meyer (1981) did show that the lateral growth rate of stromatoporoids was up to 2.18 times greater than the vertical growth rate of the coral; the vertical growth of corals exceeded those of stromatoporoids by up to 6.25 times. However, the rapid lateral growth rate of stromatoporoids would enable them to encrust and outcompete the corals within a reef community. Although large size is difficult to assess because it is a comparative term, stromatoporoid individuals have grown large skeletons, up to 1 m in height and several metres across. A laminar stromataporoid from the Middle Devonian of Iowa apparently covers an area of tens of square meters (Stearn, 1984). FinaUy, stromatoporoids have a high

skeleton-to~!>ody

ratio (> 100 : 1) because of their thin tissue.

3. Isotopie Data. During algal photosynthesis, carbon and oxygen isotopes are fractionated, and this isotopic signature may be preserved in the skeleton of the hosto Swart (1983) provided a useful summary of isotopic shifts in scleractinian corals. He iIIustrated how these stable isotopes differ in mixotrophic ("hermatypic") and heterotrophic ("ahermatypic") corals (Figure 4.10), and how the isotopie shifts are



related ta processes such as photosynthesis, respiration, and calcification. In

273



mixotrophic corals. no correlation exist~ between the oxygen and carbon isotopes in the skeleton. but they exhibit a narrow range of v:\lues due to the effect of pholOsynthesis (the carbon balance is much more under control). Photosynthesis pretèrentially tïxes t2C, thus increasing t3C/12C ratio in the host's skeleton. but has only a minor fractionating effect on the oxygen isotopes (Swan. 1983). In heterotrophic corals. the wide range of isotopic values in Figure 4.10 rel1ect variations in geometry. water temperature, growth rates. and even local isotopie regimes. Oxygen and carbon isotopes always show a positive correlation in the absence of photosynthesis; respiration and thermodynamic fractionation are the only processes affecting carbon and oxygen (Swan. 1983). Swan and Stanley (1989) used isotopic data of sorne Late Triassic scleractinian corals to suggest that symbiotic associations had developed in these corals by that time. Plotted in Figures 4.10 and 4.11 is the range of isotopic values they reponed. similar to, but outside the field of, the isotopic values of modern herrnatypic scleractinians. Isotopic data of stromatoporoid skeletons have not previously been analyzed extensively because of the difficult and delicate nature of skeletal sample extraction. Frykman (1986) plotted IWO carbon and oxygen isotope values detected in a Silurian stromatoporoid, along with data from crinoid and brachiopod specimens; no discussion of the stromatoporoid data was provided in that paper. In this study. a new microsampling apparatus at the University of Michigan (Dettrnan and Lohmann, 1995) was used in order to separate skeletal carbonate samples from gallery cements, and



274

• Figure 4.10. Comparison of carbon and oxygen stable isotopes for modem mixorrophic

and non-mixorrophic scleractinian corals, Late Triassic scleractinian corals, and Paleozoic srromatoporoids analysed in this study. Modem coral data from Swan (1983); Late Triassic coral data from Swan and Stanley (1989).

e

e· 6

Non-mixotrophic corals (Ahermatypes)

81b

4

~

2 13

1

-10

1

1

1

1

-8

-6

-4

-2

------

0

2 -2

[(]~

-4[

,

/

Mixotrophic corals (Hermatypes)

4 ~ate Triassic corals

1

"

8 C

Stromatopora cf. disCOldea

-6

çArctostroma contextum -8

-10

& lAcutatostroma stelliferum

6

276

Figure 4.11. A detailed plot of the carbon and oxygen isotope values for the

stromatoporoid species AculaIostroma stelliferum and Arctostroma contextum (both Frasnian, western Canada), and Stromatopora cf. S. discoidea (Wenlock, England). The isotope values for the latter species are comparable to Late Triassic scleractinian corals in;erpreted to be mixotrophic by Swart and Stanley (1989). Stromatoporoid isotope data from the Silurian of Gotland, Sweden (Klinteberg Formation, WenlockLudlow; Frykman, 1986) also show comparable carbon isotope values, but lighter oxygen isotope values.



e S13

C

- -- - 1 --- -----

1

2

1.5

2.5

3

a

3.5

Stromatopora

cf. discmd..

Arctostroma contextum

o

• .'~ ••

l AcuJatostroma stelliferum

Silurian, Gotland

4

278



different species of stromatoporoids were analyzed. The microsampling method is described in more detail in Appendix D. The resultant oxygen and carbon isotopes are ploned in Figures 4.10 and 4.11. and listed in Table 4.7. Table 4.7 Stable isotope data for stromatoporoids and their cements. Ô180PDB

Sample

Aculalostroma stelliferum gallery cement

Arctostroma contextum gallery cement

Stromatopora cf. S. discoidea gallery cement

Average

Standard Deviation

Average

Standard Deviation

n

-9.10

0.22

1.26

0.27

22

-8.85

-

1.04

-

1

-8.63

0.19

1.5

0.14

11

-9.00

-

0.76

-

1

-4.22

0.26

3.48

0.03

6

nia

nia

Although the skeletons have experienced diagenetic alteration (especially the Late Devo!Ùan specimens), only the oxygen isotopes were probably affected, due to changes oftemperamre with burial (Carpenter and Lohmann, 1989). More importantly, the results show an enrichment in the carbon isotope of the stromàtoporoids, and no correlation between the oxygen and carbon isotopes (Figures 4.10 and 4.11,). Stromatoporoid ske1etons are slightly more enriched in BC than their gallery cements (Table 4.7) imp1ying the preferential fixation of 12(: by photosynthesis, but more data are needed. The species Stromatopora cf. discoidea, a Middle Silurian stromatoporoid,



showed the best preservation and its isotopic values overlap with those of the Late Triassic scleractinian corals inferred to he mixotrophic. Although much more data still

'279

need to be collected, the present data support the hypothesis that these stromatoporoids hosted photosyrnbionts.

4. Habitat, Depth, and Biogeography. Modem mixotrophic corals are primarily restricted to latitudes between 0° - 30° where the marine environrnent provides warrn (> 20° C) clear waters. These restrictions are a reflection of the environrnental

requirements of the algae rather than the host (Talent. 1988). Stromatoporoid paleoecology has received much anention in the past few decades (see reviews by Stearn, 1982a; Fagerstrom, 1983). It is weil established that stromatoporoids lived in warm, tropical to subtropical, shallow water of normal marine salinity. Their uncommon occurrences in shales and sandstones suggest that they preferred clear waters, or even avoided turbid conditions, like many sponges (Fagerstrom, 1983; Stock, 1993); the main reason being that suspended particles in the water column would clog the stromatoporoid's filtration system forcing it to close down. In general, however, these characteristics are necessary for hosts of algal syrnbionts, and support the hypothesis that stromatoporoids were mixotrophic. Talent (1988) and Cowen (1983) argued that any extensive reef commu!lÎty must have had a basis in algal syrnbiosis. Modem reefs have very large populations of ,

mixotrophs. The general habitat and high calcification rates characteristic of modem reefs correlate weil with algal syrnbiotic associations. Stromatoporoids are considered the dominant and important element in most mid-Paleozoic reef communities to the same degree that scleractinian corals dominate Holocene reefs communities (Fagerstrom, 1983).

280



One of the general restrictions of algal symbioses is to areas, such as tropical latitudes, where there are no strong seasonal variations in light intensity, as in tropical latitudes.

Biogeographic reconstructions show stromatoporoids with a tropical to

subtropical distribution (Webby, 1991; Stock, 1990). In the Devonian, a few stromatoporoid faunas from Siberia and Mongolia are located between 30°- 60° N latitude (Stock, 1990); it is possible that these stromatoporoid faunas were not mixotrophic, or the Siberian plate is too far north in the paleogeographic reconstruction (Scotese, 1986). A more recent paleomap by Scotese (1993) places the Siberian and North American plates approxirnately 15° south of their placement in the paleomaps of Scotese (1986).

5. Oligorrophic Success. As described earlier, models for algal symbiosis have shown that both partners obtain the maximum benefits in oligotrophic environments. This criterion was not tested by Cowen (1988, his figure 2) for stromatoporoids. Two independant Late Devonian studies have suggested that reef building stromatoporoids thrived in oligotrophic environments. Mallamo and Geldsetzer (1991) and Mallamo et al. (1993) have suggested that part of a Late Devonian stromatoporoid carbonate complex in Alberta was affected by a local upweUing event, "poisoning" the stromatoporoid-dominated shallow water (oligotrophic) community with cooler, more turbid, nutrient-rich and oxygen-poor (i.e. eutrophic) waters. The eutrophication inhibited reef growth and consequently, the stromatoporoid reef complex was not able to keep pace with the relative rising of sea level. Portions of its margin and interior "drowned": cyclic shallow-water carbonates

281



(stromatoporoid biofacies) are overlain by deeper water limestones and basinal shales: within the reef interior, the stromatoporoid biofacies changed to a deeper water rugosc coral biofacies. The relationship be!Ween paleoceanography. water quality. and stromatoporoid reef growth is discussed in detail in Chaprer 5. In Middle Europe, Wilder (1994) has suggested that a periodic influx of

nutrients from continental runoff caused eutrophic conditions in a Lare Devonian stromatoporoid reef complex, inhibiting stromatoporoid growth and causing rugose coral reef builders to replace stromatoporoids. 6. Evolutionary Patterns. Certain characteristics of algal symbiosis in a host may r.a,1' become more pronounced with lime, and this evolutionary pattern could' provide indirect evidence for a symbiotic association in the fossil record. For example. Stanley (1981) discussed the early evolutionary patterns of fossil scleractinians in relation to the origin of their symbiotic association with algae. Scleractinian corals first appeared in the Middle Triassic, were widespread in shallow and deep environments, but did not contribute significantly as reef frame-builders. By Late Triassic time, one species had moved from deep to shallow water, where it produced extensive monospecific reef frameworks. In the early Jurassic, there was a major radiation of corals within the shallow reef environment, followed by a rapid diversification and simultaneous development of reef-building habits (Figure 4.12). Stanley (1981) concluded that at least one species had acquired symbiotic algae by latest Triassic time, and this

282

• Figure 4.12. Generic diversity of sclernctinian corals and specifie diversity of

stromatoporoids through time. Points on graph are ploned for the middle of each time series. The asterisk denotes the time in their history at which each animal first commenced significant (barrier) reef building, although patch reefs are know to have existed in the Middle Ordovician (Kapp, 1975; Webby, 1984). Scleractinian diversity data from Stanley (1981); sttomatoporoid data from Steam (1982b).





DIVERSITY OF MAJOR REEFBUILDERS

Triassic

....: Paleo- Neo- ~

Jurassic Cretac.

gene

gene 0

240 li)

ID

·0 ID Co li)

..;:.

200

Stromatoporoid Di

160

-0

.... 120

ID

..c

E ::::l"- 80

Z

40 0

-

M U L M U L

c .C1l

~

c

C1l

~

ID

iIi .::: C)

Ordoviciari

Silurian:,

c c C1l ID c E 1Il C1l E

...

C1l u.. u.. Devonian

* marks first episode as significant buildup bioconstructors

284



association spread in the Jurassic which enabled photosymbiotic scleractinians to become the dominant scleractinians and prominent reef-builders since that time. In the Late Cretaceous. scleractinians were replaced by reef building rudistid bivalves (a time during which scleractinians suffered a decrease in diversity; Figure 4.12). By analogy• an argument can be made that the history of the stromatoporoids shows evidence that indirectly supports the hypothesis that at least sorne of these calcified sponges hosted algal symbionts. Like the scleractinians. stromatoporoids simultaneously diversified and gradually expanded into and became prominent reefbuildei's (Figure 4.12). Although the first stromatoporoids (labechiids) appeared in the Early Ordovician? or the early part of the Middle Ordovician (Webby, 1980, 1994; Webby et al., 1985). stromatoporoids (in association with tabulate corals) did not construct buildups with true reefal characteristics until the early Late Ordovician (Caradoc time; Webby, 1984; Talent, 1988). This initial reef-building episode coincided with a rapid diversification that continued into the Silurian (Figure 4.12). Apart from a lapse in the Eariy Devonian, the group continued to spread until the Late Devonian. during which time stromatoporoids built enorrnous barrier reef complexes. At least sorne stromatoporoids may have acquired a symbiotic association with the dinoflagellates by the Late Ordovician; a time of stromatoporoid diversification and initial reef-building. Dinoflagellates are an extremely ancient group, with fossil remains in the Cambrian (Taylor, 1983). Talent (1988) postulated that the episodic history of organic reef-building activity was related to algal symbiosis. The pattern of



stromatoporoid reef-building episodes during the Paleozoic is coincident with the

285



panern of their skeletal growth. Mistiaen (1994) has used a computer process to calculate skeletal density in stromatoporoids. His data show that skeletal density was lowest in Early(?) and Middle Ordovician and latest Devonian' (Famennian) stromatoporoids; Givetian and Frasnian stromatoporoids showed the highest skeletal density. Concurrently, stromatoporoid reef development c1ima...ed during the Middle to Late Devonian (Givetian and Frasnian, respectively). Thus. the evolution of reef development and skeletal density of Paleozoic stromatoporoids may be explained in terrns of symbiosis; a reflection of the stromatoporoid animal gradually becoming more associated with photosynthesizing algae, and thus developing the capability for intensified skeletal growth. Although not compelling evidence by itself, the parallelism of the scleractinianlstromatoporoid scenarios is consistent with the possibility that many of the stromatoporoids benefited from algal symbiosis. The evolution and extinction panern of the stromatoporoid orders may a1so be explained in terms of symbiosis. The first known stromatoporoids, the labechiids. appeared exclusively during the early part of the Middle Ordovician and gave rise to the clathrodictyids during the Late Ordovician (Figure 4.13). During the Early Silurian, these two groups of stromatoporoids were common but gradually declined in diversity and abundance until the Late Devonian; ail' of the other orders of strornatoporoids (actinostromids, densastromatids, stromatoporids, syringostromatids, amphiporids and stromatoporellids) eventually arose from the two Ordovician groups (Figure 4.13; Steam, 1987). Thus, the symbiotic association with dinoflagellates may



have slowly been acquired or "tested" by sorne of the Late Ordovician labechiids and/or c1athrodictyids, and subsequently passed on to the other Silurian and Devonian

286

• Figure 4.13. Phylogeny of Paleozoic stromatoporoids. AIso shown is the plausible time

that certain stromatoporoid orders were hosts to photosymbionts, especially the syringostromatids, actinostromatids, stromatoporids, and stromatoporellids.

• vaU\,WOlUSONU:::>V

c====:::::=::::::=:::-:J

VanIOdIHdWV

SISOI8I1\1ASO.LOHd aIO~OdO.L'VII\IO~.LS

:1 0 311\11.L ~.

z ::;

:i LU

z

i-

~~=~1

FLUME PLATFORM YAHATINDA

West

East

315

Table 5.2. Major and minor element geochemistry of samples analysed in this part of

the study. For comparison, average shale composition from Wedepohl (1971) is included. Major elements in %; minor elements in ppm.

-

e

. i(

Tablo 5.2 Formallon

Sample 1 2 3 4

Calm

CaIrn Cairn Calm Cairn

Perdrix Perdrix Perdrix Perdrix Perdrix Perdrix Perdrix Perdrix ML Hawk

•• ••

-

7

'~_

"

12 13 14 l' lB 12

~àwk

MI. Hawk

MI.Hawk Avera Cr shale Formation CaIrn Calm Calm ëalm Calm Perdrix Perdrix Perdrhe PerdrllC Perdrix Perdrix Perdrix Perdrix MI.Hawk Mt. Hawk ML Hawk Mt.Hawk Average shalo

sample

1 2 3 4

-

•• • 7

-

0 10

."12

13 14 15 15 17

SI • 0.t3 1.03

Tl

f---~'OO

AI 0.02

0.01

0.18

0,14

0.00

0.66 14.98 1.t3

0.01 0.14

0.00 0.13

000

1.77

---0:00 0:00-

0.01 0.03

2.76 0.03 5.41 -0.06 1.97- o:ô1 3.16 0.02 0.04 4.59 5BO 0.02 8.33 0.06 0.10 7." 2.76 0.01 27.50 0.47

V 8.0 11.9 '.9 3.0 10.8 22. 18.7 16.7 28.6 19.7 7.9 12.8 75.8 23.6 20.7 24.6 13.9 130

2.58 0.26 0.53 0.46 0.93

0:25 0.27 0.61 0.48 1.13 1.00 0.20 8.84

Fe

Mn

0.03

000 0.00

Mg Ce C, Il. P C Be K COl S Ce Co 0.0 0.00 3.0B 1 36.33 0.03 0.00 '.90 50.43 0,01 _.nta .. 30 -'iD 1.0·-0.7 5.57 0.00 0.02 002 1.11 53.40 001 nta 1.0 ~ ~ 0.03 o:D1 12.78 22.48 0:00- ---0:00 0.02 3.55 45.93 r-~'O~ __ --rii3 19.7 4.9 00 0.00 - 0.00 0,02 - -3.46-- -45.82 0.07 12.77 22.40 001 0.01 -nia ~ -0:00.07 0.00 12.39 -22.08 0.00 0,01 0.00 -3~ 45.37'- -0:03 -ilf8- -25~6- -6:-9- ----0-0- ~ W.t -'63.0 . ----aJ() 1.22 0.01 0.34 17.82 0.12 r-J:g.. ~ ~- ~ -22.-7 -6.9 .- --SA0.37 0.01 12.19 21.31 0.02 009 -0:64" 3":96 41.67 -0.230.60 0.07 35.81 0.14 o:T4"" ~ 2Zl 45.51 -0.10 -----.vi- ~ -7.9' --2-:0 -1.28 ----n;a- - 20,7- ~3f.5'-. ·,(180,03 1.01 0.37 35.46 0.00 0.27 -2.69 0.19 46.13 0"".60 0.46 2.57 30.47 Qir- ~ lfi53 -0:55- 46.45 ~ 0,60- -~~ l U ---0:0 -----0-0 0.02 ~ 0.01 0.B6 37.00 0.00 0.14 --0-03 --0:4"5 54.34 022nt. ~ 2"i)~ -~ 35.25 0,01 025 001 1.28 0.11 -----032 52.aO ----O:3T -----n;a- ~ -~.f9-- 540.37 33.00 0.12 025 ---cï.07 ll:69 50.09 ~ 2597 -""""2'2.7 -~ --20-0.01 1.32 -'-i56' -'~ 6.10.50 . 0.01- ---0:« 33.47 00iJ ~ tï67 49.29 -0.13-46:3 - --5:9 ~5" 0.72 0.07 o:7t 30.27 ---o.t4 ---o::t2 QOO 2:6B 32.92 - 0.22- UT 1.10 0.02 1.97 28.IB 0.19 -o:=i8 0.09- -----n2 34~ -Q05 ------S:3 128·- 7.9 27.6 if,ô0.40 0.02 0.3d 37.01 0.04 0.05 1.41 48.75 0.18 97 4.9 -- 15.8 2.99- Ô.07 0.42 nta '0.24 5.0 95" 19.0 4.83 0.07 1.57 1.57 ~ 1.19 00

---nra-

------o-ro -nos

Zn

LOI

Ge

43.5 43.5 47.0

00

lib 00

Pb 00

.......,- --.-0 --.-0

Sr Th I~ 00 109 -00 ---ro U

~

~

1

------no ".

y

Z,

~~o -150 ---.-0 .00 180

Ag -~

A.

B,

Cd

6:3 -:iiï ------0:6 . 7.0

3.

1 -1.ro~

------o:g ---;rr-

1.6

..-,-

13. '67

~9

'69 -69 --67.0 "1"2S" -22.7- -12e' ···.f9 -17.7-- 14.8 i28 -2% - 26.,r -- 59 ··'18.7- -H~s- ·-lifS----,--s·a-- '-,2'8-148-- -11"1'1- --17"1 --246- ·-364 - 14-8 -,-[1" ·'16-7- loi! --fiT -106 - -158'-

,.2

-na'-

--16:7- '7:722.7 ioi 45.0'- -- 68:0 Mo

S.

- -0.0-- --06-'O-5~- -Ô~··-

'5 .-3:6- a.if------;t9-- ----0.0- ----0.0- ----0.0- ~ 0.0 ----;;r- ----0.0- ~ ----ao -----ufo r--J-3 7T---0.0- 5 5 ---0.0 J:o- ~ -17.i.) o., -----r6- '""5:2 1.0- --38 . --lf4----0:0 ~ ---0:0----0:0 ~g...12.0 ' ----ra:o o:S- -7:9--- 1.6- QO- 2:6- ojj-46.9 0.0 0.0 6. 0.0 3.0 0.0 0.0 ---0.0 7.2 28.0- 262 0:0 19.0 - 46.0- -52.0 ~ -13.6 - ~0.9- -,y- --'-3"7- -74"633.0 6.0 4.9 4.0 3:0-. 20-:0- 20.0, 0,0 9.7-- -5.0- 1:0--- '5~4- 1.5-45.3 0.0 0.0 0.0 56 0.0 0.5 0:1)- wT -25.0 W.O -2:3" 7 r '32 --0~6-- -17:7" ~ Og41.6 0.0 0.0 0:0~ 3.0 -"3.4- -o:s --His -1-:-1 - 39.4 -40.3 -0:0- -- 0.0- ~ 0.0 0:0- -294 ---0:0 ~ - ~{)-- -----w:o- ~2."'- --9.1" ------;rJ-. --oa'IÉfs- --o.s38.2 2.0 0.2 0.0 0:0- 305"" 0:0 ---g:o ......,-s.o ~ -1.3-- --'7:52.0 --3.0-- --0.4'- -1650.3-2:0 ~ 0 ] ) " ~ -0.0" -0.0-- -~ -(fo 1""5.() ------,a:() -rro ~ G r -3:7-0:8-- ~6- -0"'5"---,-:0- 40.7 0.0 02 0.0 0.0 16i) ----0:0- ----s:o- 12.0" 19.0 0-8-- 6'9 0:0- -0:0-- ~ 0.0 -14.0- 23:"0- 22.0" 6~3- ------e-2" -3':6 ~~ -332 ~j-' 41.4 39.4 0:0 -,-;r.o 2ï.Q- - 13.0- 0:7 G r -J.O- 0.5 -~6 0.0 732 0.0 0:0 ~ ---,-:0- --U0.0 --'0.0-3:0 34.4 ~ ~~ 0.2 ~ lQ- -1'04 - --ü:O--- 1if() -16.0- 15.0 21-- 7.7- 2:4- --oT -loa --7.3-· -3.4- .----0:6- -- ';55 -oe4:9 -3~ ~ 1:"4- ----0:0- n:O- --m--- 0 0 10.0- --16:0- -ua- -ta------0.7- - 18.4- -oa-ïao- ---rJ:() -TQ- --T4"- ------s.o 0.0 40.5 o.n 40r 0:0- ----wu 0.0 0.0 7.0 -- ioo - 40 . 0.8 -o;â'- 2. 12.0 3.7 41.0 0~1 20.0 nte 19.0 18.0 300 95 '.0 '40 00

Se

III

---5:9 "lia 7.9 - - 49-

.'lO"6 -69 ------on -138'6"9-

---o.w

0.0 0.0 0.0

Cu

',7:7

-0""3~-

-'6jf --·Qif

Do -(f1--0.5- 0,6-'-O~5--

-DG· -- (i&-(fG-

-oT- 0,6 --OG· --06'

. ïi666

126 '3' 55



317

the material analysed consists of approximately 70%-90% skelelOn and 30%-10;:;' micrite (estimated). Thus. the chemical analysis performed represents a whole-rock analysis and not a carbonate-free analysis. Chemical Composition: Results and Discussion General Features Chemical compositions of the samples show substantial variation corresponding to the variety of lithologies analysed (Table 5.2; Appendix E). The majority of the "basin" samples described as shales in the field were collected in pr0ximity to the carbonate platform margin. Consequently. these "shales" would be more appropriately described as thin-bedded or larninated clayey limestones based on their relatively high carbonate/detrital ratio. The detrital component was roughly estimated by adding the concentrations of Al203 + Ti0 2+ K20;

these values indicate that:

i) detrital

concentrations decrease in the order Mount Hawk > Perdrix > Cairn formations of the Kananaskis area; ii) a negative correlation with CaO and inorganic CO 2 exists. as expected (see correlation coefficients in Appendix E); and iii) a higher detrital component exists within the micritic than the skeletal samples of the Cairn Formation, as expected. MgO was not used to evaluate the detrital component of the samples because of the uncertain amounts of dolomitization. However, the high concentrations of MgO (>20%) probably refiect the completely dolomitized limestone samples (3, 4, and 5) that were noted in the field. The distribution of individual major and minoielements is exarnined mainly by means of elementlAl ratios. This allows the concentration of the elements to be normalized with the concentration of an element that is a chernically conservative

318 indicator of detrital input. Al serves as a reference element for the alurninosilicate fraction of the sediment and can be used to identify relative element enrichments and depletions from the background clastic sediment. Comparisons are made with average shale compositions (used as a proxy for "crustal abundances") as provided by Wedepohl (1971).

Major Elements The concentrations of Al203 and Ti02 of the Fairhlome samples are strongly correlated (Figure 5.3a), as in most detrital sediments and black shales (Calven, 1976; Pratt and Davis, 1992). The Si/,AJ ratio is generally higher in Mount Hawk samples (Figure 5.4) perhaps suggesting that the quartzlclay mineral ratio is higher than in the

.

-

Perdrix Formation. X-ray diffraction analysis of samples from the Jasper region (Hopkins, 1972) show the opposite trend; this discrepancy might be explained by comparing the SilA! ratios of this study to average shale values. The high SilA! ratio of the Fairholme samples (Figure 5.4) may reflect a biogenic origin rather than a detrital origin for a portion of the Si. In a similar manner, Fe203 correlates reasonably weil with A!203 and Ti02 (Figure 5.3b) suggesting that a portion of the iron is detrital. But samples with higher Fel AI ratios than average shale also indicate that sorne of the iron may be authigenic or even biogenic. Similarily, the PIA! ratios are much higher than those of background levels (average shale), and may be indictative of the presence of organic P (Figure 5.4). However, PIA! shows no correlation with organic carbon, nor the carbonate fraction, but shows a moderate correlation (0.6) with FelAl (Appendix E) perhaps also reflecting an authigenic origin.



319 Organic Carbon. The absence of correlation between organic carbon and

Al~03

(Figure 5.3c) or Ti. and the Corg/AI ratios (Appendix E) suggests that terrigenious factors such as ciastic dilution or transportation of woody plant debris were not the dominant controls on the accumulation of organic maner. The other probable source of the organic carbon is the marine realm controlled by such factors such as algal productivity and degradation. Creaney (1989) has documented the marine source for the organic matter of the Duvemay Formation in the Alberta subsurface. Organic carbon shows a strong negative correlation with the carbonate content. as expected (Figure 5.7a). The organic carbon concentrations in this study confirm previous notions that the dark grey Cairn Formation contains more organic carbon (2Ïo 12 times) than the light grey Peechee Member; and, the Perdrix Formation is generally more organicrich !han the Mt. Hawk Formation. The latter observation is comparable to the results of correlative Strata in the Jasper area (Hopkins, 1972) and the Alberta subsurface (Duvemay Formation; Creaney, 1989). Although the organic carbon content varies considerably within the Cairn Formation, the Upper Cairn Member contains up to 3.55 wt. % that is comparable to organic-rich source rock shales. The Sundance Range samples showed a marked increase in organic carbon content from 1.1 wt. % in the stromatoporoid biofacies to 3.55 wt. % in the coral biofacies. In the basinal succession, the organic carbon content is the highest in the middle part of the Perdrix Formation (6.3 % at Cinquefoil

320



Figure 5.3. (a) Cross plot of the concentration of aluminum versus titanium expressed as oxides. Boxed value (in this and subsequent cross plots) is the correlation coefficient for the two sets of values being compared; a strong correlation tends toward the value l, a poor correlation tends toward 0, a negative correlation is expressed as a negative value between 0 and -1. Note the strong correlation between aluminum and titanium. (b) Cross plot of the concentration of iron versus titanium expressed as oxides.

(c) Cross plot of the concentration of organic carbon versus aluminum oxide. Note the poor correlation.

O)~

400

ëti

300

en

200

.S UJ

._-----~----------~-_._~----~--------------~

100

...

N

. ',:-' ~ Thus, the presence of IlBr ratios higher than ur.ity, the presente of IIC (organic) ratios higher !han thosr\jf anoxic sediments, and the enrichment of Mn concentrations relative to crustal abundances imply that these sarnples of the Cairn, Perdrix, and Mt. Hawk formations of the Kananaskis-Banff region tnay have been



deposited under oxygenated water conditions. The absence of enriched concentrations



348

of Cr, Mo, and Zn (Figure 5.9 and Table 5.2) relative to crustal abundances supports this interpretation. Discussion and Summary A preliminary examinaùon of the bulk geochemical composiùon oi" various lithologies of the Cairn, Perdrix, and Mt. Hawk formaùons reveal new evidence regarding the paleoceanographic processes and chemistry that influenced the development of the Fairholme carbonate complex. An increase of paleo-producùvity probably due to upwelling of nutrients occurred during the Ùffie represented by conodont RM Zones 2 to 4a, and possibly Zone Sb. Conodont Zone 2 coincides with the'biofacies change observed within the Upper Cairn Member; Zone Sb coincides with the ÙIDe of Grotto deposiùon (dominated by coralline growth at many localiùes). Thus, a cause and effect relaù0ns.hip between paleoceanography and reef growth is implied. The implicaùon that sediments of the Perdrix Formaùon were deposited under an oxic water column challenges the idea that this unit only represents deposiùon in an euxinic environment (Mountjoy, 1980; Stoakes, 1980; Mallamo and Geldsetzer, 1991; and many others). This interpretation is primarily b~ed on the black, organic-rich, and laminated characteristics of typical Perdrix lithologies. As discussed earlier, the black, organic-rich characters may not necessarily be due to anoxic conditions, but could alternatively he interpreted as a result of high primary productivity, or both. Considering the very low sedimentation rates, both mechanisms may be necessary to explain such high organic carbon concentrations. The commonly laminated lithologies



of the Perdrix'Formaùon (and generallack of burrowing) may reflect subsurface anoxia



349

just a few centimeters or even millimeœrs below the sediment/water interface. rather than water colurnn anoxia. as suggested by the Mn! Al and IlBr ratios in this study. It is clear from the results of this study that (bio)stratigraphic and sedimentological studies of such topics as depositional envirOllments are greatly augmented by integration with geocbemistry.



350

PART 2: LATE DEVONIAN PALEOCLIMATE AND ITS INFLlJENCE ON STROMATOPOROID CARBONATE PLATFORMS

Introduction Ocean currents, winds, and wind-generated wave energy are physical factors commonly uùlized by sedimentologists to better understand carbonate buildup dynarnics and associated basin-fil! sediment dispersal patterns. A col!ecùon of Upper Devonian studies of western Canada spanning the last 40 years have promoted, and attempted to determine paleocurrent direcùons to help interpret the development of various buildup margins (Andrichuk and Wonfor, 1954; Andrichuk, 1961; Klovan, 1964; Dooge, 1966; Stoakes, 1980; Morrow and Geldsetzer, 1989; Wendte, 1992, MèLean and Mountjoy, 1993). Only the last study listed above focussed on the western part of the Frasnian reef domain of Alberta. Unfortunately, little inforrnaùon is provided in these studies concerning the nature of these paleocurrents, their depth or extent, and overall pattern(s); the area: of study is often at a much finer scale than the global scale of the paleocurrents being considered. In addition, an inherent assumpùon exists tha: the ·direcùon of paleowinds and wind-generated paleocurrents were entirely parallel, both from the northeast of present-day Alberta (Klovan, :964; Wendte, 1992; McLean and Mountjoy, 1993). Fu::therrnore, the interpretation of paleocurrent directions and patterns were geologic-based (from the distribution and trends of basin-fill s~diment), not considering additional independant evidence or guidelines such as oceanographie

351



principles and paleogeography. Understandably. this was in part due to the limils to knowledge of paleoceanography at the time of study. Stoakes (1980: his table 1) sununarized the published accounts up to that time of Upper Devonian paleocurrent data in central Alberta: ail workers (including Stoakes. 1980) suggested a present-day northerly (NE-N'W) paleocurrent direction. The main line of reasoning that developed and supported this paleocurrent direction was the interpretation that the source of basin-fill sediments (Perdri"fDuvernay and Mount HawklIreton) was from the north or northeast (Stoakes. 1980; Mountjoy. 1980) perhaps from the Ellesmerian Orogeny in the Arctic (Morrow and Geldsetzer. 1989). During the Middle and Late Devonian, paleogeographic reconstructions indicate that the mountainous terrain in the Arctic region was situated easmortheast of Alberta ($cotese,

1993; Golonka et al.,

1994; see Figure 5.18). The paleocurrent

interpretations were based.()n work that showed evidence of an overall east-to-west progradation of basinal StlO.ta in the Alberta subsurface (Oliver and Cowper, 1963) suggesting a general northeast-southwest regional pattern of basin filling (Stoakes, 1980; Mountjoy, 1980). Paleocurrents transported sediment southward, between the Peace River Arch landmass and the Grosmont carbonate shelf, and toward the East Sbale Basin through Leduc buildups of the Rimbey-Meadowbrook trend (Stoakes, 1980). Recent work have supponed and followed this interpretation (Wendte, 1992: McLean and Mountjoy, 1993). However, aspects of Devonian paleoceanography still remain to be clarified: (a) the exact mechanism of transport of basinal sediment from the north, winds or

.,'

35~



currents?: (b) the effect of oceanic surface currents on the dispersal patterns of hasinfil! sediment: (c) the influence of wind-generated surface wave energv ( < 20 nù versus

-

deeper water (> 50 m) oceanic currents on

--

th~

developmel1f of carhonate huilùup

margins: and (d) the possible effects of a vast deep ocean basin westward anù immediate!y adjacent to the reef domain. The following assumptions are followed in this study and are discussed in later sections: (i) Atmosplzeric Circulation. Surface paleowinds created near-surface wave energy that was partially absorbed by Devonian carbonate buildup margins (red crests). Paleowinds had the capacity to transport fine sediment great distances (possibly a few thousand kilometers, e.g_ across the present-day Atlantic Ocean l'rom northeast Africa to the Caribbean Sea). They controlled general oceanic current patterns. and caused oceanic surface divergence resulting in oceanic upwelling: (ii) Oceanic circulation. Paleocurrents (approximately 50 to 200 m depths) controlled basin-fil1 distribution patterns, indirectly influencing the development of buildup margins and their 'relief adjacent to the basin seafloor. They also transported nutrient-rich, and oxygen-poor waters from depth during upwelling events.

In this part of the chapter, Devonian paleoclimate will be evaluated in the context of carbonate buildup and basin-fill dynamics. The development of the paleoclimatic model utilizes our current knowlege of modern ol'eanography. but is also lirnited to: (i) difficulties of uniforrnitarianism; (ii) availability and usefulness of data; (iii) dating problems and imprecision; and (iv) paleogeographic reconstructions.



353



Modern Oceanography Atrnospheric Circulation At present, the primary driving force for aunospheric circulation is the· distribution and exchange of heat belWeen the equator and the poles, with hot air rising at the equator and cool air sinking at the poles. The general circulation panern is modified by the rotation of the earth and the differential heating between land and oceans (Barron and Moore, 1994). The effect of rotation (Coriolis force) does not permit direct heat exchange belWeen the equator and the poles. The Coriolis effect deflects moving air to the right in the northern hemisphere and to the left in the southern hemisphere, Le. it deflects equatorward-moving air to the west and po1ewardmoving air tG the east (Figure 5.11; Parrish, 1982). Since rising air causes low barometric pressure and sinking air causes high barometric pressure, a low pressure zone is formed at the equator by warm rising equatorial air; a subtropical high pressure be1t is formed at latitude 300 where the air cools and sinks (Figure 5.11; Parrish, 1982; Barron and Moore, 1994). Thus air rising at the equator and sinking at mid-latitudes forms a cell known as the Had1ey ce11. The intermediate cells, belWeen 30 0 and 60 0 are known as Ferre1 cells, which force equatorial air to sink at 30 0 and polar air to rise at 60 0 • This general

ZO!llÙ

panern is

modelled on an homogenous earth (i.e. with no continents; Figure 5.11). In the present worid where the major continents trend mainly north-south across the climatic zones, aunospheric circulation is disrupted locally because land gains and loses heat faster than the oceans. The zonal system of high and low pressure belts is best developed

• 00 1-----1---+---+----1

Ij D

Law Pressure

Surface Winds

High Pressure

Figure 5.11. Distribution of surface winds and atrnospheric pressure on an earth with no continents (from Parrish. 1982).

,k--H +-- / Figure 5.12. Present surface currents of the world's oceans during the northern hemisphere winter, showing relative high (H) and low (L) atmospheric pressure zones (adapted from Williams et al., 1973).



355 over the oceans. whercas over the continents. seasonal geostrophic winds Ce.g. monsoons) and more intense high and low pressure systems are generated (parrish. 1982; Scotese and Summerhayes, 1986). Oceanic Surface Currents Three major controls of ocean water moùon are uneven heating of the earth. wind acùng on the ocean surface (pickard and Emery, 1982), and the configuraùon of the continents; the latter two controls deserve comment because this discussion is concemed primarily with wind driven surface cUuents. Exccpt at 60° S latitude, no

ocean currents run all the way around the worid because of the interference of land masses (Figure 5.12; Williams et al., 1973). When a wind blows it exerts a force on the ocean surface setting a series of layers (about 100 m thick) into motion, anè. due to the Coriolis force the net moùon of water is directed at right angles to the wind direction (pickard and Emery, 1982); this has been observed since 1902, and conftrmed mathemaùcally by F.W. Ekman in 1905 (Williams et al., 1973; Barron and Moore, 1994). Initially, the uppermost layer is detlected only slightly, but through friction layers below the uppermost layer are set in motion and are also defiected by the Coriolis effect. With depth, the defiection of these layers increases and the speed of the water associated with the wind stress decreases, resulting in a spiral of increasing defIecùon and decreasing motion called the Ekman spiral (Barron and Moore, 1994). In the Northem Hemisphere water motion is defiected to the right of the wind direction, and the left in the Southem Hemisphere.

356 This is called Ekman transport. and the slab of water from the surfact' to the point of zero motion is called the Ekman la\'er (parrish. 1982). For example. between latitudes 30° N and the equator. the northeast winds cause the Ekman layer to move toward the notùwest (Figlire 5.13). Similarily between 30° N and 60° N, the southwest winds transport the Ekman layer to the right and a southeast fIow develops. The resultant currents flow towards each other at around 30° N and "pile up" water within this region creating a high pressure ridge in the hydrosphere.The effecf of this pressure distribution and the Coriolis force will produce a geostrophic fIow southwestward between the equator and 30° N, and northwestward between 30° N and 60° N. Since land masses bound most of the oceans, a current gyre (called the subtropical gyre) is produced in a clock..wise direction around the high pressure cell at around 30° N (Figure 5.13). In the Northern Hemisphere, a clod..wise rotation is found about a high pressure cell as it does in the atrnospheric mode!. The opposite rotation applies in the Southem Hemisphere. In ail of the world' s oceans there is a sub-tropical gyre, and the example in the North Atlantic Ocean is composed of the North Equatorial, the Gulf Stream System, and the Canary currents (Williams et al.. 1973). The surface ocean current system is asymmetrical about the equator because the trade wind system is asymmetrical. a situation which is caused by the asymmetrical distribution of land and ocean about the equator (pickard and Emery. 1982). In the equatorial regions there exists a low pressure trough in the hydrosphere

because the winds transport oceanÏC' surface waters away from the equator in both directions, and a "depression" results (Figure 5.13). Two current gyres, north and



(1) (1)

'oC(

:E

c zoC(

..J

WATERFLOW

I~

EQUATOR r1 ---f-----~~~DE~P~R§jES~S[EIOffiN~=_---1 ~

,~ \;;

WATERFLOW

Figure 5.13. Schematic diagram of a basic ocean current model for Northem Hemisphere wind driven currents. IIIustrated is the production of oceanic low and high pressure areas hy prevailing winds. At the equator, note the production of IWO gyres from the single depression (adapted from Williams et al., 1973).

358



south equatorial gyres, are produced since flow direction about the low pressure cell is opposite in the different hemispheres:

in the Northern Hemisphere with a

counterclock:wise rotation and in the Southern Hemiphere with a c10ckwise rotati0n (Figure 5.13). In the North Pacific Ocean, the north equatorial gyre is weil developed and is composed of an westward-flowing north equatorial current (NEC) and an oppositely flowing equatorial counter current (BCC) north of the equator. South of the equator, a westward-flowing south equatorial current (SEC) comprises part of the south equatorial gyre. At 60° laùtudes, the situation may be treated similarily. The winds cause surface waters to move so as to create a low pressure trough. The resultant subpolar gyre will flow in a counterc!ock.-w;Je direcùon in the Northern Hemisphere. clock.'Wise in the Southern Hemisphere. At present, the Antarcùc Circumpolar and the Antarcùc subpolar currents make up a sub-polar gyre in the South Pacific Ocean (Williams et al., 1973). The Equatorial Undercurrent in the Pacific Ocean is a strong, eastward-flowing current at the equator below the SEC; it remained unknown to oceanographers. until 1952 (pickard and Emery, 1982). The EUC is a resu1t of the easterly trade winds along the equator raising the surface-water elevation to the western part of the Pacific. The resultant surface gradient causes the thermocline to adjust hydrostatically, causing meridional subsurface pressure gradients (Gill, .. 1982; Jewell, 1995). These pressure

,-

gradients are geostrophically balanced away from the equator by the Coriolis effect, but not at the equator and flow is eastward directly down the pressure gradient.

359 Predicting Zones of Oceanic Upwell1ng Upwelling is an ascending motion in the ocean by wlùch waters from below (usually from depths of a few hundred meters) are brought into the surface layer as a result of horizontal surface divergence. Subsequently, the upwelling waters are removed from the area of upwelling by horizontal flow (Smit.l-t, 1973). Considerable anention has been given to the prediction of upwelling zones because they are potential sites of petroleum source rock generation (Demaison and Mooft:. 1980; Parrish, 1982; Parrish and Curtis, 1982; Scotese and Summerhayes, 1986). Sediments associated with upwelling are usually enriched in phosj::horus (and associated elements; see part 1 of tlùs chapter), opaline si1ica, and marine organic carbon due mainly to the lùgh organic productivity within the photic zone above (Baturin, 1983; Barron and Moore, 1994). The major limiting factor of tlùs marine organic productivity is the supply of nutrients to the photic zone, and tlùs can be aclùeved by: (1) coastal erosion and river input; and by (2) up;velling of waters rich in nutrients from below. To the geologist, upwelling currents that are persistent, large sca1e, and winddriven are most important because they leave behind a distinct impression in the sedimentary record (parrish, 1982; Barron and Moore, 1994), and it is these persistent types of upwelling that are evaluated in tlùs study and others (e.g. Parrish, 1982) so that they may be applied to the prediction of upwelling in the pasto Two types of wind driven upwelling commonly occur today: open ocean (includes symmetrica1 and radial types) and one-sided or coastal (see Figure 5.14).

TYPES OF UPWELLING

4

/

/

/

/

, ! /

/

/

/

/

/

4

ONE-SIDED

Zone of Upwelling

Wind Driven Currents

Winds

Figure 5.14. Schematic diagram of upwelling types (from Parrish, 1982). Wind and water currents are ilIustrated J'or northem hemisphere, except for equatorial area. Radial and symmctrical upwelling occurs under stable, low atmospheric pressure systems.

361



Rcmembering that the net transport of oceanic surface waters is to the right of the prevail ing wind direction in the Northern Hemisphere and to the left in the Southern Hemisphere. open ocean upwelling develops in regions of wind convergence and of low atmospheric pressure. For example, symmetrical upwelling occurs around Antarctica (Figure 5.15) because a low pressure belt surrounds the hemisphere and the winds (the westerlies and !he polar easterlies) converge from opposite directions; water is transported at right angles to the wind direction away froi:! the centre of the low pressure as a result. Around a low atrnospheric pressure cell. the winds spiral into it so that the wind vectors are almost parallel with the isobars. As a result, the net transport of wind-dri':en water is at right angles to the wind direction and water at the surface (upper 10's of meters) is driven away from the center of the low pressure ceU (Figure 5.14). At the equator, the winds converge from the same direction but because the Coriolis effect "changes sign" across the equator, divergence of the surface waters occurs and upwelling occurs (Figure 5.14). To maintain upwelling at a level as to affect organic productivity within the photic zone, very strong and continuous tradewinds are necessary since the Coriolis force is negligible at the equator. Today, the tradewinds are the strongest on the eastern side of oceans and equatoriàl upwelling commoniy produces higher organic productivity (parrish, 1982). Coastal or one-sided upwelling requires that constant winds blow paraUel to the coast and from the proper direction. Today, the most intense upwelling is off the west .

coasts of cCIitînents (Smith, 1973). Off the coast of western South America, low level



winds

are

deflected

by

coastal

mountains

so

that

the

winds

blow



PRESENT PRODUCTIVITY OF MARINE WATERS

Net Primary Productivity (gC/m2/yr) 0-100

over200

1100-200

1

Figure 5.15. Present primary productivity of marine waters. Areas of upwelling arc areas of organic carbon productivity over 200 gC/m'/yr (l'rom Parrish. 1982).

r----------------',,-----..., COASTAL UPWELLING Wind Driven Currents

j

_-~~~~~~,F"~,~",,,/,/, / /

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/

/

/

/

/

/

/

/

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Figure 5.16. Schematic cross section of coastal upwelling and flooding of nutrient-rich, oxygen-poor waters over a continental shelf.

363



northward, paraUel to the coast. Since Ekman transport is 90 0 to the left of wind vectors in the Southem Hemisphere, the net flow of surface waters is to the left of Pero, or offshore, and upwelling results. A similar example in the Northern Hemisphere occurs off the shore of California, only there the winds blow southward and paraUel to the coast; thus the average Ekman transport is aiso offshore (as schematicaUy shown in Figure 5.16). Two other major zones of coastal upwelling occur off northwestem and southwestem Africa. Each of these zones of upwelling are associated with intense marine primary productivity. The Effects of Upwelling and the Association with Primary Productivity UpweIling will considerably modify the distribution of chemical and physical properties in the ocean's surface layer. Smith (1973) discusses these effects, which are summarized herein: (1) the surface water temperatures are markedly below normal for the latitude, as much as 2 - 3oC cooler; (2) the surface salinity decreases. Salinity normally decreases with depth in the oceans to a minimum value at several hundred meters (one exception occurs in the upwelling region of the California Current where salinity increases with depth); (3) surface waters become undersaturated with respect to oxygen, reported to be as low as 6 % of saturation off the southwest coast of Africa, and 35 % of saturation in the Pero Current region; (4) phosphate concentrations increase by ten times or more in upwelling regions. Other



dissolved nutrients and trace metals also increase, including organic carbon, Cd, Zn, Si, and Cu;

3t>-\



(5) mean sea level may be lowered sterically. i.e. the result of an isostatie adjustment of the more dense. cooler upwelled waters (unfortunately. no values were œportel.!): (6) climate is altered by way of a decrease in air temperature and an increase in the relative humidity (fog is common) in the upwelling region. Also. upwelling will increase the strength of the cool. onshore sea breezes which are driven hy the

incre~lsed

temperature difference over the land and the ocean during the summer. The distribution of upwelling regions in today's oceans are difficult to document because the vertical ve!ocities of upwelling waters are smal1. on the order of 10-3 cm per second (Smith, 1973; Barron and Moore, 1994). But because upwcl1ing is usual1y induced by the wind, lIpwelling is calculated l'rom surface wind stress data derived from modem wind observations. A study by Krujis and Barran (1990) uscd modern surface wind stress data (from Hellerman and Rosenstein, 1983) to calculate and map present regions of upwelling, and the distribution of present upwelling regions were compared with areas of primary productivity. Surprisingly, the results of their study showed that the relationship between primary productivity and upwelling is not obvious; only 18% of the upwelling regions were associated with primary productivity greater than 90 gC/m2/year. Without qualifications, they concluded that upwelling is generally not a good indicator of productivity, although productivity is a good indicator of upwelling (Krujis and Barron, 1990). However, Krujis and Barran (1990) showed that the relationship between upwelling and productivity improves considerably with qualifications. They reported That 63 % of the regions of high productivity are



associated with upwelling if two regions are removed l'rom their comparison: (i) open ocean, and; (ii) high latitude regions which are seasonally or annual1y covered by sea

365



ice (sea ice regions were not masked by the wind stress data set of Hellennan and Rosenstein. (1983». The association between upwelling and productivity in coastal regions improves more if aspects of seasonal upwelling are known. Krujis and Barron (1990) showed that strong upwelling in one season and weak upwelling in the other season had the best association (91 %) with high primary productivity. Nutrient Supply and Reer Environments In modem reef environments, Hallock (1988) and Hallock et al. (1988) have shown the devastating effects an increase in nutrient supply has on light-dependent, hennatypic scleractinian corals and the reefs they help build. As discussed in previous sections, nutrients can enter shallow-water environments basically by the turnover of upwelling deeper waters, by runoff from land, or by the advection from areas of upwelling or runoff (Hallock and Schiager, 1986). It has been noted that there is a scarcity of hennatypic corals in high-nutrient environments (Birkeland, 1977; Hallock and Schlager, 1986; Hallock et al., 1988). Nitrogen, phosphorus, and trace elements are essential nutrients used by photosynthesizing organisms in the production of organic matter. The negative influence of nutrient excess on hennatypic coral reef development presents a paradox, if one considers that nutrients are essential for plants, which provide food for animais. Various explanations have been suggested for this apparent paradox, such as the reduction of water clarity, biotic disruption, and increased bioerosion (Hallock and Schiager, 1986). Wood (1993) reviewed the trophic structure of modem tropical benthic communities, mainiy reefs, and their relationship



366



to

nutrient supply. Her nutrient limitation mode!. based on numerous studies. is

summarized in Table 5.5 and discussed below. Reduction of water transparency is one of the major physical mechanisms hy which nutrient excess suppresses modem reefal growth rates. Today. water transparency is controlled primarily by chlorophYll and organic carbon content in areas where terrigenous runoff has no influence (Kinsey and Davies. 1979; Hallock. 1988). and as a consequence. an increase in nutrient supply increases planktonic densities. thereby reducing water transparency. Thus. total carbonate productivity of the reef community is diminished because nutrient excess decreases the depth ranges (i.e. decreases the euphotic zone) of hermatypic corals and calcareous algae (Hallock and Schlager, 1986). The euphotic zone is considered to be the depth to which 1 % of midday surface irradiance penetrates; in very clear waters, the euphotic zone can exceed depths of 130 m (Hallock, 1988). Although the most prolific reef growth is limited to depths of 10 to 20 m, euphotic zone still remains a useful and convenienl term to compare water clarity between regions. For example, well-developed modem reefs are constructed in the western Pacific and parts of the Caribbean Sea by hermatypic corals under oligotrophic conditions where the euphotic zone typically reaches 100 m or more (Table 5.5). ln pligotrophic waters, production of carbonate sands is high; bioerosion and carbonate ~.



mud production is limited. Mesotrophic conditions exist in the Florida Keys where the

367



Table 5.5. List of physical factors that influence styles of reef-building, sediment type,

and conununity structure in modern, shallow marine tropical environments. AlI factors are described within a biological time frame. ln part compiled by Wood (1993) from various sources, including Birkeland (1977), Littler and Littler (1985), Hallock and Schlager (1986), and Hallock (1988). Arrows symbolize intermediate phases between extremes.



368

Table S.S PHYSICAL FACTORS Inorganic flXed nitrate NutrienlS Turbidity Sediment input Emironmental stability Water transparency Recyeling Typical geographical area Sediment Charaeterisùes Muds Skeietal sands

> 10 !LM High High High Low Low Low

7Sm

Coceoliths Mixotrophs Benthie photo- and mixotrophs

Meridional upwelling

Low Mesotrophie SOm Dinoflagellates Aigae Benthie algae

Eutrophie b

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427



APPENDIXC: STROMATOPOROID TERMINOLOGY

The following is a glossary of terms used in the stromataporoid descriptions in Chapter 3 and 4. This glossary is part of a larger collection of terms compiled by C.W. Stearn and B.D. Webby (unpublished).

Orientations (a) Vertical section is perpendicular to the growth surface, and tangential section is approximately paraIlel to the growth surface of skeletons of laminar, domical, or bulbous shape. (b) Longitudinal section is oriented to intersect the long axis of a column or branch,

transverse section is perpendicular ta the long axis, and tangential section is approximately parallel tO the long axis but intersecting the outer margin of the column or branch of digitate skeleiliiiS.

Definitions of Skeietal Elements Skeleton is all the hard tissue secreted by the orgaxüsm. Skeletal structure is defmed by the laminae, pillars and other elements of the skeleton. Growth surface is any level in the skeleton where addition to. the surface is contemporaneous; basal and terminal refer to the first and last surfaces of skeletai growth. Epitheca is a thin layer of fine structure above the basal growth surface; bounded above' by normal skeletai tissue. Latilamina (plural, latilaminae) is a lateraily continuous set of layers of skeletai tissue bounded above and below by changes in the form of the skeletai tissue. Lamina (plural, laxninae) is a lateraily extensive skeletai plate or net paraIlel to the growth surface; it may be single layered or tripartite, i.e. with a less opaque central zone, a line of cellules in the central zoneiordinicellular) or an opaque axial microlamina, or it may he composed of multipli. microlaminae.



428 Microlamina is a thin, laterally persistent skeletal plate that may be part of a lamina, or a single element parallel to the growth surface. Gallery is the interlaminar

~l1ace

bounded by pillars and other internai elements (e.g.

dissepiments). Cyst is an upwardly or outwardly convex skeletal plate arranged parallel to the growth surface in the Order Labechiida. Dissepiment is an upwardly convex or inclined plate occupying the interlaminar space: also applied to the parutions in coenotubes and astTorhizal canals. Pore is an opening of rounded section through a lamina. Foramina is a large pore. Colliculus is a rod which joins others to form a net parallel to the growth surface in the Order Actinostromatida. Amalgamate structure is a three-dimensional network in which discrete,

persist~nt

strUctural elements, parallel the growth surface, are poorly differentiated. Coenostrome is the part of the amalgamate net which parallels the growth surface in the Order Stromatoporida.

Pillar is a skeletal rod (rarely a plate) oriented perpendicular to the growth surface: may be long, continuous through laminae and interlaminar spaces, and columnar, or may be confined to an interlarninar space, upwardly conical, spool-shaped, or upwardly inflected into laminae. Pillars of the Order Labechiida may be circular, irregular, meandriform or bladed in section. Megapillar is a rod-like strUcture of a larger order of magnitude Lhan the pillars. Papilla is a rounded uppermost extension of a pillar on the terminal growth surface. Coenostele is the part of the amalgamate net which occupies a position perpendicular to .:::- -:

the growth surface, and is normally meandriform in tangential section, in the Order Stromatoporida. Coenotube is an elongate gallery aligned normal to the growth surface; meandriform, irregular or circular in tangential section, bounded by amalgamate net of coenosteles ,

and coenostromes, internally divided by dissepiments, in the Order Stromatoporida. .

Astrorhiza is a set of radiating and branching grooves which join in a stellate system on the terminal growth surface.



429 Astrorhizal canal forms part of a stellate, radiating or branching, walled or unwalled canal system in the interlaminar spaces; these canals may be parritioned by tabulae. Mamelon is a raised, rounded area of skeletal tissue on the terminal growth surface. Mamelon colurnn is a structure of upwardly inflected laminae or cysts forrned by the superposition of marrdor!s.

Microstructures (in light nùcroscopy) Specks - equidimensional, opaque areas a few micrometers across, white in reflected light. Compact - specks, evenly distributed. define the skeletal elements. Where opaque, areas are somewhat uevenly distributed (the terrnflocculent has been applied). Fibrtius - crystal boundaries in the structural elements oriented perpendicular to their

margins. MeIanospheric - opaque, subspherical concentrations of specks more than ten micrometers across. Cellular - translucent subcircular areas (cellules) more than ten micrometers across in a more opaque speclded structural element.

430



APPENDIXD: STABLE ISOTOPES, MICROSA1\lPLING METHOD

The following summarizes a microsampling method for stable isotopes (Denman and Lohmann, 1995) used in the analysis of stromatoporoids at the University of Michigan. A more detailed description of the microsampling method is provided by Dettman and Lohmann (1995). Polished thin sections (approximately 100 flm thick) ,lf stromatoporoid specimens were prepared for sampling. A computer controlled. stepper-motor-driven. x-y-:;:

rnicropositioning stage was used to manipulate the sample under a stationary

rotating drill

bit~

Standard optical rnicropositioning stages allowed the positioning

precision of 1 flIIl when driven by the stepper motors. The stepper motors were controlled through a computer inteface and motor driver that allowed simultaneous control of position and travel speed for all three axes. Drilling cuts were specified to typically 50 flm deep and 20 flIIl wide; at these parameters roughly 4 mm of travel was needed to acquire enough sample (minimum 10 flg of carbonate) for one analysis using the University of Michigan gas ratio mass spectrometer (Finnigan MAT 251). After each sample path is drilled, the powder is removed to a small stainless steel boat using a pointed scalpel blade. The drill used is a high-precision industrial dental hand-piece. Samples were heated under vacuum for 1 hour (at 3800 C) and loaded iUlO separate glass reaction vessels. An autornated sample reaction device digests sample powder with three drops of anhydrous phosphoric acid in an individual reaction vessel at 740 C. The combination of a micro-inlet and individual reaction vessels (which prevents cross-sample contamination) allows analysis of very small samples (Dettrnan and Lehmann, 1995).

Dettman, D.L. and Loh:nann, K.C., 1995. Microsampling carbonates for stable isotope and minor element analysis: Physical separation of samples on a 20 micrometer scale. Journal of Sedimentary Research, v. A65, p. 566-569.



431

APPENDIXE: MAJOR A.l''D MINOR ELEMENT GEOCHEMISTRY

Table E.l. Correlation Coefficients of element/AI ratios

Table E.2. Correlation Coefficients of elements (tables on next rwo pages)

e

Table E.l. Correlation coefficients of element/AI ratios C03

C03 Corg SI/AI Fe/AI Mn/AI Mg/AI Ca/AI Na/AI P/AI Co/AI Cr/AI Cu/AI NI/AI V/AI Zn/AI S/AI Ag/AI As/AI Cd/AI Mo/AI Se/AI

Corg

SIIAI

Fe/AI

Mn/AI Mg/AI

Ca/AI

Na/AI

1.0 -0.8 1.0 0.4 -0.5 1.0 0.3 -0.1 0.3 1.0 0.1 -0.1 0.5 1.0 0.1 0.2 0.1 -0.1 0.4 0.0 1.0 0.1 0.5 0.1 0.9 0.2 -0.1 1.0 0.1 0.0 0.0 0.5 0.1 0.8 1.0 1.0 0.2 0.0 0.1 0.6 0.3 -0.3 -0.2 ·0.3 0.0 0.4 0.0 0.7 0.2 0.6 0.5 0.4 -0.5 0.5 -0.1 0.1 -0.1 -0.3 -0.3 -0.3 0.2 0.0 0.1 0.6 0.1 0.9 1.0 1.0 0.2 0.0 0.1 0.6 0.0 0.9 1.0 0.9 0.2 0.0 0.1 0.5 0.0 0.9 1.0 1.0 0.2 -0.3 -0.1 -0.1 0.2 -0.1 0.1 0.4 0.2 0.0 0.3 0.5 0.1 0.0 0.1 0.1 0.2 -0.1 0.1 0.5 0.1 0.9 1.0 1.0 0.5 0.1 0.9 1.0 1.0 0.2 0.0 0.1 0.5 0.0 0.9 1.0 1.0 0.2 0.0 0.1 -0.5 0.6 -0.1 -0.3 -0.4 -0.1 -0.2 -0.2 0.1 0.9 1.0 1.0 0.2 -0.1 0.5 0.1

P/AI

1.0 0.4 0.4 -0.2 -0.1 -0.2 0.8 0.5 ·0.2 -0.2 -0.2 -0.1 -0.2

Co/AI

Cr/AI

Cu/AI

1.0 1.0 0.1 0.6 ·0.3 1.0 0.6 -0.2 1.0 0.5 -0.3 1.0 0.3 0.1 -0.1 0.4 0.3 0.1 1.0 0.5 -0.3 -0.3 1.0 0.6 0.5 -0.3 1.0 0.0 0.3 -0.2 0.5 -0.3 1.0

NI/AI

1.0 1.0 -0.1 0.2 1.C ~.O

·1.0 -0.1 1.0

Zn/AI

S/AI

Ag/AI

As/AI

1.0 0.0 1.0 0.2 1- 0.5 1.0 -0.1 1.0 -0.2 1.0 -0.2 0.0 0.2 1.0 -0.2

1.0 0.1 0.1 0.1 0.3 0.1

1.0 1.0 1.0 -0.2 1.0

1.0 1.0 -0.2 1.0

VIAl

Cd/AI Mo/AI

1.0 -0.2 1.0

1.0 -0.2

So/AI

1.0

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