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Ucin1060260362.Pdf (3.4 UNIVERSITY OF CINCINNATI DATE: 08/01/2003 I, Funda Özlem TOPRAK , hereby submit this as part of the requirements for the degree of: Master of Science in: Arts & Sciences, Geology It is entitled: High-Resolution Chemostratigraphic Correlation of the Lower Silurian (Llandovery) Osmundsberg K-bentonite in Baltoscandia and Northern Europe Approved by: Dr. Warren D. Huff Dr. J. Barry Maynard Dr. Thomas J. Algeo HIGH-RESOLUTION CHEMOSTRATIGRAPHIC CORRELATION OF THE LOWER SILURIAN (LLANDOVERY) OSMUNDBERG K-BENTONITE IN BALTOSCANDIA AND NORTHERN EUROPE A thesis submitted to the Division of Research and Advanced Studies of the University of Cincinnati in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in the Department of Geology of the College of Arts and Sciences 2003 by Funda Özlem Toprak B.S., Middle East Technical University, 1999 Committee Chair: Dr. Warren D. Huff ABSTRACT The Lower Silurian Osmundsberg K-bentonite is a widespread ash bed that occurs throughout Baltoscandia and parts of northern Europe. The sections containing the Osmundsberg K-bentonite beds were investigated to determine if chemical composition of these beds can be used as a basis for high-resolution chemostratigraphic correlation on a regional scale. Fifteen Osmundsberg K-bentonite samples and twenty-six samples of accompanying beds from twelve different localities were analyzed for major and trace elements and the data statistically treated using discriminant function analysis to determine if the trace element data provides a unique chemical fingerprint for the Osmundsberg K-bentonite beds. Comparison with the correlation model drawn by Bergström et al. (1998) based on biostratigraphic evidence show that results from two independent techniques are generally in agreement. Results demonstrate the unique and identifiable chemical fingerprint of the Osmundsberg K-bentonite bed can provide an additional stratigraphic tool for local and regional correlation of these K-bentonites. ACKNOWLEDGEMENTS I gratefully acknowledge the assistance of all people who made significant contribution to this thesis. I express especial gratitude and appreciation to Dr. Warren D. Huff, my advisor, for introducing me to the fascinating world of clays and for all his continuous support, excellent ability of instruction, help, advice, friendship, and patience without which this thesis would not have come alive. I have greatly benefited from his knowledge and experiences. Special thanks are extended to members of my advisory committee. Dr. Thomas J. Algeo and Dr. J. Barry Maynard for their constructive criticism and valuable advice that were essential to the completion of this study. I should thank to the organizations who courteously provided assistance in many forms. These include, the Clay Minerals Society, the Ford Nuclear Reactor at Michigan, the Department of Geology at the University of Cincinnati. I am also thankful to Evelyn Pence, Sandi Cannell, Brian Nicklen, Burcin Inanli and Atia Huff for their patience to my endless questions and for their support and advice. Finally, I would like to thank to my mother; Esin Toprak for sending her warm support with daily messages, my father; Yakup Toprak for his understanding and encouraging me to start this academic program in University of Cincinnati, my brother; Mustafa Toprak for his love and support enabled me to complete this study. TABLE OF CONTENTS ABSTRACT ...........................................................................................................................................2 ACKNOWLEDGEMENTS...................................................................................................................4 LIST OF FIGURES................................................................................................................................ii LIST OF TABLES .................................................................................................................................v INTRODUCTION..................................................................................................................................1 1.1. Purpose of the Study...................................................................................................................5 1.2. Previous Work on K-bentonites in Europe................................................................................6 GENERAL GEOLOGY.........................................................................................................................8 2.1. Paleogeography of the Study Area ............................................................................................8 2.2. Stratigraphy of the Study Area.................................................................................................11 METHODS OF INVESTIGATION....................................................................................................20 3.1. Electron Microprobe Analysis .................................................................................................20 3.2. Instrumental Neutron Activation Analysis..............................................................................22 3.3. Powder X-Ray Diffraction Analysis........................................................................................23 3.4. Scanning Electron Microscope Analysis.................................................................................25 RESULTS AND DISCUSSIONS........................................................................................................27 4.1. MINERALOGY .......................................................................................................................27 4.1.1. Clay Mineralogy ...............................................................................................................27 4.1.2. Non-Clay Mineralogy.......................................................................................................32 4.2. GEOCHEMISTRY AND TECTONIC SETTING..................................................................39 4.2.1.Biotite Geochemistry .........................................................................................................46 4.3. BINARY DISCRIMINATION DIAGRAMS .........................................................................51 4.3.1. Plots of Osmundsberg K-bentonite group........................................................................52 4.3.2. Comparative Plots of Osmundsberg and other K-bentonite groups................................52 4.3.3. Discussion of the Binary Discrimination diagrams .........................................................57 4.4. DISCRIMINANT FUNCTION ANALYSIS..........................................................................58 4.4.1. Results of Discriminant Function Analysis......................................................................62 4.4.2. Discussion of The Results of the Discriminant Function Analysis.................................84 DISCUSSION AND CONCLUSIONS...............................................................................................87 REFERENCES.....................................................................................................................................93 APPENDIX A ....................................................................................................................................100 APPENDIX B.....................................................................................................................................106 APPENDIX C.....................................................................................................................................115 i LIST OF FIGURES Figure 1.1. Diagram showing the correlation of the Osmundsberg K-bentonite. Figure 2.1. Sketch-map of paleogeography of the northern Iapetus region in Lower Silurian (Llandovery) time Figure 2.2. Sketch map showing geographic location of investigated Telychian K- bentonite sections in Baltoscandia and the British Isles. Figure 2.3. K-bentonite succession in the Osmundsberget section, the type section of the Osmundsberg K-bentonite. Figure 2.4. The type section of the Osmundsberg K-bentonite Figure 2.5. The lower parts of the type section of the Osmundsberg K-bentonite Figure 2.6. 115 cm thick Osmundsberg K-bentonite in its type section in the Siljan district, Dalarna Figure 4.1. Representative powder X-ray diffraction tracings of ethylene glycolated, < 2mm fraction of the Osmundsberg K-bentonite beds Figure 4.2. Mixed layer illite-smectite X-ray diffraction tracings of the Osmundsberg K-bentonite from its type locality by using computer program NEWMOD Figure 4.3. Mixed layer illite-smectite X-ray diffraction tracings of the some representative Osmundsberg K-bentonite samples using NEWMOD. Figure 4.4. Photomicrographs of characteristic phenocrysts from the Osmundsberg K- bentonite bed ii Figure 4.5. SEM images of primary volcanogenic phenocrysts from the Osmundsberg K-bentonite bed Figure 4.6. General chemical profile of fresh biotite phenocrysts of the Osmundsberg K-bentonite bed Figure 4.7. General chemical profile of zircon crystals of the Osmundsberg K- bentonite bed Figure 4.8. General chemical profile of apatite crystals of the Osmundsberg K- bentonite bed Figure 4.9. Plot of fifteen Osmundsberg samples on a granite discrimination diagram Figure 4.10. Th/Yb versus Ta/Yb plot of the Osmundsberg K-bentonite samples Figure 4.11. Plot of Osmundsberg K-bentonite samples on a Th-Hf-Ta tectonic discrimination
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