Carbonate Platform Slopes — A Record of Changing Conditions: The Pliocene of the Bahamas

205 Pages·1998·5.61 MB·English

by  Hildegard Westphal (auth.)

Lecture Notes in Earth Sciences 75
Editors:
.S Bhattacharji, Brooklyn
G. M. Friedman, Brooklyn and Troy
H. J. Neugebauer, Bonn
A. Seilacher, Tuebingen and Yale
regnirpS
Berlin
Heidelberg
New York
Barcelona
Budapest
Hong Kong
London
Milan
Paris
Singapore
Tokyo
Hildegard Westphal
Carbonate
Platform Slopes
A Record
of Changing
Conditions
The Pliocene of the Bahamas
With 56 Figures and 10 Tables
regnirpS
egard Westphal
iel School for Marine and Atmospheric Sciences
L of Marine Geology and Geophysics
:kenbacker Causeway, Miami, FL 33149-1098, USA
E-mail: hwestphal @rsmas.miami.edu
"For all Lecture Notes in Earth Sciences published till now please see final pages of
the book"
Cataloging-in-Publication data applied for
Die Deutsche Bibliothek - CIP-Einheitsaufnahme
Westphal, HUdegard:
Carbonate platform slopes - a record of changing conditions : the
pliocene of the Bahamas ; with 10 tables / Hildegard Westphal. -
Berlin ; Heidelberg ; New York ; Barcelona ; Budapest ; Hong Kong
; London ; Milan ; Paris ; Singapore ; Tokyo : Springer, 1998
(Lecture holes in earth sciences ; 75)
ISBN 3-540-64646-9
ISSN 0930-0317
ISBN 3-540-64646-9 Springer-Verlag Berlin Heidelberg New York
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To Stefan who shares my love for science
Preface
This book represents the author's doctorals thesis. Therefore, although it is a
monograph, it represents the results of numerous discussions and cooperations.
First of all I am grateful to Christian Dullo (GEOMAR, Kiel/Germany) for
supervising my work on this thesis, for valuable suggestions, and for providing
support whenever I needed it. I want to thank John J. G. Reijmer (GEOMAR,
Kiel), who initiated my work on core CLINO, who was involved in the sampling
of core CLINO in Miami, and who with many discussions and hints was of
continuous help.
I am especially thankful to Robert N. Ginsburg and Gregor P. Eberli
(Comparative Sedimentology Laboratory at Rosenstiel School of Marine and
Atmospheric Sciences, University of Miami) for giving me the opportunity to
study the core CLINO of the Bahamas Drilling Project, and for providing
information on the work done by the Miami group. Jeroen Kenter introduced me
to the core and suggested the selection of the intervals that were studied in this
thesis. Flavio Anselmetti, Gregor Eberli, Don McNeill, Leslie Melim, and Peter
Swart were extremely helpful in providing information, unpublished figures, and
data on the Bahamas Drilling Project. To Leslie, I am particularly indebted for
many discussions and for a review of the diagenesis part of the present manuscript.
Peter Swart performed some stable isotope measurements for calibrating the data
of the present study with the data previously obtained at the RSMAS. To Karin
Bernett I am indebted for some later sampling of the core. Mike Grammer and
Pamela Reid kindly provided recent fecal pellets and Halimeda specimens from the
Bahamas and Florida for comparison with the fossil ones present in CLINO.
Christian Samtleben and Axel Munnecke (Universit~t Kiel) introduced me to
the art of scanning electron microscopy. The numerous fruitful discussions
strongly influenced the development of this thesis. To Axel, I am grateful for
directing my focus on the diagenesis of micritic limestones and the development of
microspar. Also, he kindly reviewed an earlier version of the present manuscript.
Bob Goldstein (University of Kansas/Lawrence) did the fluid inclusions
measurements. Discussions with him on a predictive diagenetic model were a lot
of fun.
The co-operation with Martin Head (Toronto University), who did the
palynological examinations of my samples and took the micrographs of the
palynological slides, was highly interesting. I am very grateful that he taught me a
t01 on palynomorphs. Thanks to Thomas Servais (Universit6 de Lille) for rising
my interest for palynomorphs. Wolfram Brenner (GEOMAR Kiel) and Hans Gocht
(Universitat Tfibingen) helped me with the work on dinoflagellate cysts.
Klaus Vogel (Universit~t Frankfurt) helped with the determination of burrows
in pellets. On the determination of foraminifers I have learned from Christoph
Hemleben, Ulrike Wieland (both Universit~it TiJbingen), and Dorothee Spiegler
(GEOMAR Kiel). Xin Su (Beijing University) had a look at a coccolith specimen.
viii Preface
The measurements of stable isotopes were performed in the laboratory of
Michael Joachimski at the University of Erlangen/Germany. Thanks a lot To
Tom Aigner and Markus Schauer (both Universi~t Tiibingen) I am grateful for the
possibility to test the luminescence of my samples with the cathodoluminescence
device of their department.
To Adam Vecsei (Universit~it Freiburg) I am indebted for the review of the
sediment input-part of this thesis. The entire thesis greatly benefited from peer
reviews of related manuscripts by Julian E. Andrews, Roger Barnaby, Robin G. C.
Bathurst, Mark Harris, Zak Lasemi, Leslie Melim, and Bruce W. Sellwood.
Many thanks are due to Werner Ricken (Universit/it K61n) for various
discussions on carbonate diagenesis and for reviewing one of the manuscripts prior
to submission.
Stefan Bornholdt (Universit~it Kiel) did a final check of the manuscript. Also,
he accompanied the progress of my work with many discussions from the critical
point of view of a theoretical physicist.
Thanks a lot to my brother Frank E. Westphal (Darmstadt) for drawing the
overview of the Bahamas (figure 1). For the information on the origin of the name
of the Bahamas I wish to thank Axel Pinck (Hamburg).
No study would be possible without discussions and exchange of experience in
an agreeable working environment. Explicitly I want to mention discussions with
Florian B6hm and Dierk Blomeier. Niels Andresen performed the calibration
measurements of the X-ray diffractometer. Rebecca Rendle, as a native speaker,
checked the English language. Ingo GlUer was a very capable research assistant.
Also to the other colleagues: thanks for the good working atmosphere at
!RAMOEG
For technical assistance at the SEM, I want to thank Werner Reimann
(Universit~it Kiel), who does the best coatings of SEM stubs. Ute Schuldt
(Universit~t Kiel) assisted with excellent photographical work. To GEOMAR I am
grateful for providing the facilities. Especially I want to thank the librarian
Angelika Finke, who was a patient and competent help.
Financially, this study was supported by the German Science Foundation (DFG
Re 105 I/3) and the Studienstiftung des deutschen Volkes. Also, the non-financial
support of the Studienstiftung is gratefully acknowledged. The core CLINO was
collected with funding from the United States National Science Foundation under
Grants OCE 891-7295 and OCE 910-4294, from the Industrial Associates of the
Comparative Sedimentology Laboratory of the Rosenstiel School of Marine and
Atmospheric Sciences and from the Swiss National Science Foundation.
Last but not least, I wish to express my sincere thanks to my familiy who
always accompanied my work with warm interesst and who supported me in
numerous ways.
It is a pleasure to acknowledge the cooperation with Springer Vedag, especially
with W. Engel during the preparation of this book.
Hildegard Westphal, Miami/Florida May 1998
Contents
Introduction 1
1.1 Geology and Research History of the Bahamas 1
1.1.1 Recent Morphology 1
1.1.2 Origin of the Bahamas 3
1.1.2.1 Basement of the Bahamas 3
1.1.2.2 Origin of the Morphology 5
1.1.3 Ramp versus Steep-Sided: Morphologic Evolution and Sea-Level 7
1.2 Objectives 01
Study Area and Material 1 3
2.1 The Bahamas Drilling Project 31
2.2 Sampling and Material examined 71
Methods 19
3.1 Compositional Analysis 91
3.1.1 Point Counting 91
3.1.2 Quantitative Analysis of Foraminiferal Associations 22
3.1.3 Palynologic Examinations 24
3.2 Stable Isotopes 24
3.3 X-ray Diffractometry 25
3.4 Scanning Electron Microscopy 26
3.5 Total Organic Carbon 27
3.6 Fluid Inclusions 28
Primary Signals - Sediment Input 2 9
4.1 Periplatform setanobraC 29
4.2 Results of the Compositional Examinations 13
4.2.1 Components 13
4.2.1.1 Skeletal Components 33
4.2.1.2 Non-Skeletal Components 40
4.2.2 Quantitative Compositional Analysis 42
4.2.2.1 Distribution within Upper Pliocene Interval 42
4.2.2.2 Distribution within Lower Pliocene Interval 43
4.2.3 Numerical Analyses of the Point-Count Results 48
4.2.3.1 Statistics of the Upper Pliocene Composition 48
4.2.3.2 Statistics of the Lower Pllocene Composition 52
4.2.4 Foraminiferal Assemblages 55
4.2.4.1 Distribution of Foraminifers in the Upper Pliocene 55
4.2.4.2 Distribution of Foraminifers in the Lower Pliocene 56
4.2.4.3 Environmental Significance of Foraminiferal Assemblages 59
4.2.5 Microfacies Descriptions 60
x Contents
4.2.5. l Upper Pliocene Microfacies 61
4.2.5.2. Lower Pliocene Microfacies 67
4.3 Discussion - Compositional Signatures in Periplafform Sediments 70
4.3.1. Sediment Composition, Palynomorphs,
and Sea-Level Fluctuations 70
4.3.2 Sedimentation of the Upper Pliocene Succession 72
4.3.3 Sedimentation of the Lower Pliocene Succession 78
4.3.4 Sequence Stratigraphic Implications 84
4.4 Conclusions 85
Secondary Signals - Diagenesis 8 9
5.1 Carbonate Diagenesis 89
5.2 Results 95
5.2.1 Stable Isotopes 95
5.2.2 X-Ray Diffraction 95
5.2.3 Organic Carbon 98
5.2.4 Textural Alterations - SEM and Light-Microscopic Results 99
5.2.4.1 Diagenetic Alterations of the "Groundmass" 99
5.2.4.2 Diagenetic Alterations of Sedimentary Components 104
5.2.5 Description of Ultrafacies 107
5.2.5.1 SEM Observations in Samples with Fine-Grained Matrix 107
5.2.5.2 SEM Observations in Grainstones 111
5.2.6 Fluid Inclusions 112
5.3 Discussion - Diagenesis of Periplatform Carbonates 114
5.3.1 Diagenetic Environment 114
5.3.1.1 Stable Isotopic Signatures 114
5.3.1.2 Stable Isotopes and Ultrafacies 116
5.3.1.3 Significance of Alterations with Respect to the
Diagenetic Environment 118
5.3.2 Mineralogic Record 119
5.3.3 Lithification Model 124
5.3.4 Cemented versus Uncemented Layers 130
5.3.4.1 Compaction Assessment in Fine-Grained Carbonates 131
5.3.4.2 Source of the Carbonate Cement 130
5.3.4.3 Causes for Diagenetic Differentiation 141
5.3.5 Origin of Diagenetic Fluids 138
5.4 Conclusions 148
6 Outlook 151
References 153
Contents ix
Appendices 171
Appendix -1 Plates (light microscopy and SEM)
Appendix 2 - Palynomorph Assemblages