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'Tillite', Boston Basin SEDIMENTOLOGY OF THE SQUANTUM ‘TILLITE’, BOSTON BASIN, USA: MODERN ANALOGUES AND IMPLICATIONS FOR THE PALEOCLIMATE DURING THE GASKIERS GLACIATION (c. 580 Ma) by Shannon Leigh Carto A thesis submitted in conformity with the requirements for the degree of Doctorate of Philosophy Graduate Department of Geology University of Toronto © Copyright by Shannon Leigh Carto, 2011 SEDIMENTOLOGY OF THE SQUANTUM ‘TILLITE’, BOSTON BASIN, USA: MODERN ANALOGUES AND IMPLICATIONS FOR THE PALEOCLIMATE DURING THE GASKIERS GLACIATION (c. 580 Ma) Shannon Leigh Carto Doctorate of Philosophy, 2011 Graduate Department of Geology University of Toronto ABSTRACT The Gaskiers glaciation (c. 580 Ma) has been classically traced along the Neoproterozoic Avalonian-Cadomian Terranes, which are now found scattered around the North Atlantic Ocean. Around 625 Ma these terranes were composed of volcanoes and arc- type basins. ‗Till-like‘ diamictite horizons identified within these basins have been used as evidence for a ‗Snowball Earth-type‘ glaciation at 580 Ma. However, others argue that these deposits are non-glacial debris flow deposits. To test the non-glacial interpretation of these deposits, a detailed sedimentological and basin analysis was conducted on the Neoproterozoic Squantum Member that occurs conformably with the volcanic-sedimentary rocks of the Boston Bay Group (eastern Massachusetts); this deposit is one of the most referenced ‗tillite‘ deposits for the Gaskiers glaciation. This thesis shows that the ‗tillites‘ of this succession are volcanically-influenced non-glacial debrites. Using the Lesser Antilles Arc and the adjacent Grenada Basin in the Caribbean Sea as a modern depositional analogue for the Avalonian- Cadomian Terranes, this study further reveals that debris flow facies types (diamicts) comparable to those of the Avalonian-Cadomian Terranes are produced at this modern arc and are recorded in the fill of the Grenada Basin. A similar study was conducted on the modern diamicts produced at the heavily glaciated Mount Rainier volcano (Washington, USA), ii revealing that despite the presence of local glaciers, debris flow is the dominant process depositing diamicts due to eruptions and flood events. The major thrust of this thesis is that it highlights the key role of tectonics and volcanism, not glaciation, in producing the diamictites of the Avalonian-Cadomian Terranes, and the importance of examining Neoproterozoic diamictite facies in their wider sedimentary, stratigraphic and tectonic context. iii ACKNOWLEDGEMENTS When I first embarked on this journey almost five years ago the most that I hoped to attain was a Ph.D. Now as my journey comes to an end I realize I am coming away with so much more. In addition to acquiring an invaluable set of skills and a sound knowledge base in paleoclimatology, I have also learned important life lessons, built life-long friendships, and now proudly possess a ‘worn and torn’ passport that bears the memory of the many adventures I had while acquiring my Ph.D.; adventures which took me from one coast of North America to the other and to the tops of fiery volcanoes and icy mountains. Most importantly, I am coming away with the feeling that I have waited patiently for since I sat down with my first chemistry set at age eight that, at last, I am a scientist. For all these gifts and opportunities that have been bestowed on me, it is a pleasure to thank the many people who made them possible. Foremost, I would like to express my sincere gratitude to my advisor, Dr. Nick Eyles. Throughout my Ph.D. program he provided me with motivation, immense knowledge, sound advice, good teaching, and lots of great ideas. He challenged me to think harder, to think outside the preverbal box and challenge established dogma in the field of paleoclimatology. I would also like to thank the other members of my Ph.D. committee, Dr. Andrew Miall, Dr. Uli Wortmann, Dr. Mathew Wells and Dr. Emmanuelle Arnaud for their detailed and constructive comments, encouragement and all the support they have provided me with throughout my Ph.D. program. I would also like to thank my many student colleagues for providing a stimulating and fun environment in which to learn and grow. I am especially grateful to my dear friends, Angela Falcon and Louise Daurio, for taking time out of their lives and busy school schedules to assist me in the field. Come rain, shine, snow or extreme heat they were by my side as we climbed active volcanoes and glaciated mountains, trekked through the notorious woods of ‘Big-foot’, escaped the witches of Salem, and navigated the ‘two-lane’ roads of the Caribbean, all in search of that elusive ‘pay dirt’; they are responsible for the warm feelings and memories that I have from my Ph.D. None of this would have been possible without them and I am immensely proud and grateful to call them my friends. I can only hope that our adventures are not over and that ‘Charlie’s Angels’ will ride again. I would also like to thank Kathy Wallace and Tom Meulendyk. Although, our time together has been short, I am grateful for all the laughs, support and advice that we have been able to share. iv I am forever indebted to Mike Doughty and Tom Meulendyk for their assistance with the preparation of the graphics for my thesis. Despite their own rigorous schedules and work commitments they provided me with the highest quality of work and were always willing to work within the constraints of my thesis schedule. It is difficult to find the words that adequately convey the depth of my gratitude to my friends, who despite the distance of oceans, continents and city blocks, have always provided me with endless support, motivation, enthusiasm and have brought so much joy to my life. I am forever grateful to you all for the shoulders you provided me with to lean on, for listening to my thesis writing ‘woes’ and for all the laughs, girls’ night outs, weekend getaways, and the many pep-talks which helped me make the bad times good and good times better. Most importantly, I wish to thank my parents, Annette and Colyn Carto and my sister Candice for their endless encouragement and support. I have been blessed to have a sister who is not only a great friend but my biggest fan. I truly believe that without her support and role modeling I would not be where I am today. She is the most disciplined, fiercy intelligent and hard-working woman I know. I am especially grateful to my parents who have always supported me in the choices I have made (whether they liked them or not) and who always encouraged me to go after my dreams, no matter how big, no matter how impossible. I am especially thankful to my mother who spent many hours proof- reading the chapters of my thesis and who, along with my father, was always ready to give me kind words of support and encouragement during difficult times. Last, but definitely not least, I would be remised to not thank by little buddy Pete who spent many long days and long nights by my side as I typed, read and typed some more. I don’t how I would have gotten through it all without you. Having you in my life is a blessing and a constant joy. ~There is a single light of science, and to brighten it anywhere is to brighten it everywhere~ Isaac Asimov v TABLE OF CONTENTS ABSTRACT……………………………………………………………………..…..................ii ACKNOWLEDGEMENTS ………………………………………………………….………iv TABLE OF CONTENTS………………………………………………………………...…...vi LIST OF FIGURES ……………………………………………………………………..........ix LIST OF TABLES…………………………………………………………………..….…....xvi CHAPTER 1: INTRODUCTION……………………………………………….……..…1 1.1 STUDY RATIONALE…………………………………………………......................1 1.2 OBJECTIVES AND STRUCTURE OF THESIS.………………………..……...…...5 REFERENCES………………………………………………………….…………….….........10 CHAPTER 2: NON-GLACIAL, DEEP WATER MASS FLOW ORIGIN FOR THE NEOPROTEROZOIC SQUANTUM ‘TILLITE’ (BOSTON BASIN, USA): NO EVIDENCE OF SNOWBALL EARTH DURING THE GASKIERS GLACIATION AT c. 580 Ma...……………….…….............15 ABSTRACT……………………….………………….………………………………..............15 2.1 INTRODUCTION AND PURPOSE OF STUDY.….……....……………....................17 2.2 PHYSICAL SETTING AND STRATIGRAPHY OF THE BOSTON BASIN…………………………..………………….…..................18 2.3 PREVIOUS INVESTIGATIONS AND AGE OF THE SQUANTUM MEMBER……………………….………………………..............21 2.4 SCOPE OF STUDY AND METHODS ……………….…………….………...............23 2.5 DESCRIPTION AND INTERPRETATION OF LITHOFACIES..……...…................24 2.5.1 Conglomerate facies………………………………………………..……..........25 Interpretation………………………..………………..………...............28 2.5.2 Sandstone facies…………………………………………………..………........31 Interpretation………………………………………………...................32 2.5.3 Diamictite facies…………………………………………………..…...…........33 Interpretation…………………………………………………...............36 2.5.4 Argillite facies……………………………………………………...…........…..38 Interpretation…………………………………………...........…............40 2.5.5 Volcanic-sedimentary facies…..…………………………….…........................41 2.6 DEPOSITIONAL AND TECTONIC SETTING……..…………………....…..............43 2.7 DISCUSSION………………………………….…………………………....................47 2.8 CONCLUSIONS……………...…………………………………………...…..............54 REFERENCES……………………………………………………………………...................79 CHAPTER 3: REINTERPRETATION OF ‘ICE-RAFTED’ PEBBLY ARGILLITES OF THE NEOPROTEROZOIC SQUANTUM MEMBER, BOSTON BASIN, USA AS NON-GLACIAL DEBRITE-TURBIDITE COUPLETS ………………………………………………………….…….……….…......….97 ABSTRACT………………………………………………….….…………………..….…......97 3.1 INTRODUCTION AND PURPOSE OF STUDY ……………………..…..…..….….99 3.2 GEOLOGICAL SETTING, STRATIGRAPHY vi AND
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