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Cenozoic Contourite Drifts and Palaeoceanographic Development of the Faeroe- Shetland Basin

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Cenozoic Contourite Drifts and Palaeoceanographic Development of the Faeroe- Shetland Basin Ca r d if f UNIVERSITY PRIFYSGOL Cae RDY|§> CENOZOIC CONTOURITE DRIFTS AND PALAEOCEANOGRAPHIC DEVELOPMENT OF THE FAEROE- SHETLAND BASIN MICHAEL WILLIAM HOHBEIN Submitted in partial fulfilment of the requirements for the degree of Ph.D. Cardiff University December 2005 UMI Number: U584790 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI U584790 Published by ProQuest LLC 2013. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 DECLARATION This work has not pre\iously been accepted in substance for any degree and is not being concurrently submitted in candidature for anv denree. M 1 / '' Signed C .. .( .............................................. (candidate) Date. STATEMENT 1 This thesis is the result of my own investigations, except w here otherwise stated. Other sources are acknowledged by footnotes giving explicit references. A bibliography is appended. Sinned (candidate) Date STATEMENT 2 1 herebv give consent for my thesis, if accepted, to be available for photocopying and for inter-library loan, and for the title and summary to be made available to outside ornanisations. Sinned.. .(candidate) I dedicate this thesis in memory' o f my grandfathers, Ron Hohbein and Maurice Luck, who sparked my interest in geology at an early age Summary This thesis investigated the palaeoceanographic history of the Faeroe Shetland Basin, NE Atlantic, via identification and analysis of contourite drift deposits using petroleum industry seismic and well data. Integration of regional 2D seismic lines, 3D seismic volumes and high resolution seismic profiles with industrial well data permitted full spatial and temporal characterisation of the contourites within the basin, including identification of small scale architectural elements and subtle stratigraphic relationships. In turn, it was possible to make interpretations regarding the palaeoceanographic regime within the basin from the onset and evolution of thermohaline current flow through the basin to correlation with the present day oceanographic situation. Overall, the study serves to highlight the efficacy of industrial seismic and well data for contourite and palaeoceanographic research. A variety of contourite drift types were identified during seismic-chronostratigraphic division of the Cenozoic succession. Identification of an early middle Eocene contourite drift within the southern Faeroe Shetland Basin dates the onset of southerly flowing deep waters from the Norwegian Greenland Sea into the North Atlantic as part of a North Atlantic Conveyor Belt-style circulation system at approximately 49 million years, predating previous estimates by more than 15 million years. The presence of Oligocene, Miocene and Pliocene contourite drifts within the basin reveals that following initiation in the middle Eocene, southerly flowing deep water circulation through the basin was continuous throughout the late Palaeocene and Neogene to the present day. A gradual increase in deep water flux through the basin throughout this time is hypothesised based on contourite distribution, and is thought to relate to the global greenhouse to icehouse climatic transition that occurred during the Cenozoic. Pulses of increased deep water current velocity related to a combination of climatic and tectonic factors are thought to be responsible for the formation of major deep water erosional unconformities which are associated with the contourite drift successions. A link between contourite deposition and the climatic fluctuations that characterised the late Neogene northern hemisphere is also proposed based on the identification of direct indicators of significant glaciation including iceberg plough marks within the contourite drift units. Contourite drift deposition is interpreted to occur predominantly during climatically warmer episodes, while periods of glaciation are characterised by apparent disruption of ocean current circulation within the basin. Acknowledgements Writing these words fills me with a combination of giddying joy and slight trepidation. After what feels like a long journey, I would like to thank those who helped me along the way, and if I forget anyone to whom thanks are owed, which I fear is inevitable, I thank you too. First and foremost, I would like to thank Prof. Joe Cartwright with utmost sincerity for giving me the opportunity to undertake this research, and for his continued mentoring and guidance throughout the project, which has been absolutely invaluable. Cheers Joe. I would also like to thank the organisations without whom this project would not have been possible. I am grateful to the Natural Environment Research Council and Shell U.K. Ltd for funding the research. I am also grateful to BP, Conoco Phillips, ExxonMobil, Amerada Hess, Total, Veritas DGC, PGS, Schlumberger, Western Geophysical, Fugro-Geoteam AS, TGS Nopec and the British Geological Survey for providing data which enabled me to complete this study. Schlumberger are thanked for providing the means to interpret the seismic data, in the form of software and hardware. Thanks also to the 3Dlab managers, Neil and Gwen, for providing technical support and advice, and to Gwen for her computer related support. I would like to acknowledge the staff and students of the earth science department for advice, support and friendship during the course of my study. All of the staff members who's door 1 hav e knocked on asking advice are gratefully thanked for their time and input. 1 thank the members and affiliates of the 3D lab, past and present, for making the 3Dlab such a good place to be. In particular, Paul Knutz is thanked for his input into the project at the beginning, and Richard Davies, Mads Huuse and David James are thanked for their time and advice, which was extremely valuable and is greatly appreciated. Thanks to all of the students of the lab for making it the place it is, in particular Dorthe Hansen for among other things her seemingly inexhaustible knowledge of Geoquest and also Mairi Nelson & Claudia Bertoni. A v ery special thanks goes to my fellow office-comrades; Andy Robinson, Valente Ricoy, Jose Frey, Rob Evans and Mostyn Wall, for all the work related and non-work related discussions and laughs and helping me survive my stint in 3.16. Cheers guys. There are a few other people I would like to thank. Thanks to Jon Trueman and BP for being so forthcoming in supplying data and giving his time, Russell Wynn and Doug Masson for their perspectives, thoughts and time, which had a big impact on development of some of my ideas, Dorrik Stow for giving me the opportunity to view contourites in the field and Huw Edwards and Chris Drage for allowing me to visit PGS to look at the FSB mega-merge. Sincere thanks also to Sharon and Terry for all your help and support. Finally, and perhaps most importantly, 1 would like to thank my family: Mum, Dad, Chris and my Nans. Without your continued support, both moral and financial, throughout my educational career, I could never have got to here, and so I am entirely indebted to you. Thank you. And of course Lins, without your unfaltering, unconditional support and patience over the past 3 years I seriously doubt whether I could have made it. Thank you so much. Note regarding thesis structure This thesis consists of three main research components. Chapters Two, Three and Four, which have been prepared in the style of scientific papers for submittal to international journals. The status of each chapter at the time of submittal of the thesis is summarised below: Chapter Two is in final preparation for submittal to Paleoceanography as 'A Middle- Eocene onset of the Xorth Atlantic Conveyor Belt: evidence from the Faeroe-Shetland Basin ’. Hohbein, M.W. and Cartwright, J.A. Chapter Three is in final preparation for submittal to Marine Geology as Late Palaeogene-Neogene contourite drifts and palaeoceanographic evolution o f the Faeroe Shetland Basin ’. Hohbein, M.W. and Cartwright, J.A. Chapter Four has been submitted to Marine Geology as 3D seismic analysis o f the West Shetland Drift system: implications for late Neogene palaeoceanography o f the NE A tlantic'. Hohbein, M.W. and Cartwright. J.A., and is in review. IV Table of contents Summary ...................................................................................................................................... i Acknowledgements ................................................................................................................... ii Note regarding thesis structure ...............................................................................................iv Table of contents ........................................................................................................................v List of Figures............................................................................................................................. ix Appendices .................................................................................................................................. xx Chapter One 1.
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