INVESTIGATING THE COUPLING BETWEEN TECTONICS, CLIMATE AND SEDIMENTARY BASIN DEVELOPMENT by Todd M. Engelder A Dissertation submitted to the faculty of the DEPARTMENT OF GEOSCIENCES In partial fulfillment of the requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2012 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Todd M. Engelder entitled “Investigating the effects of climate, tectonics and sedimentary basin development” and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy _______________________________________________________________________ Date: February 17, 2012 Jon Pelletier _______________________________________________________________________ Date: February 17, 2012 Peter DeCelles _______________________________________________________________________ Date: February 17, 2012 Paul Kapp _______________________________________________________________________ Date: February 17, 2012 Clement Chase _______________________________________________________________________ Date: February 17, 2012 Peter Reiners Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ________________________________________________ Date: February 17, 2012 Dissertation Director: Jon Pelletier STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the author. SIGNED: Todd M. Engelder 4 ACKNOWLEDGEMENTS I would like to start out by thanking my committee and especially my advisor Jon Pelletier for helpful suggestions and guidance during my research. Finishing my PhD would not have been possible without financial support from Exxon Mobil through the COSA project. I thank my colleagues Dave Pearson, Jon Volkmer and Ross Waldrip for fielding countless questions about structural geology when I couldn’t locate DeCelles or Kapp. Thank you Caitlin Orem, Onne Crouvi and previous officemates for the many long discussions we had about Geomorphology and life in general. Finally, thank you Josh Spinler, Alexander Rohrmann, James Girardi, Andrew Kowler, Mark Warren, Meg Blome, Mark Trees, Mauricio Ibanez-Mejia, Maria Banks and friends outside of Tucson for helping me to “constructively” spend the few hours that I was not focusing on geology. 5 DEDICATION I dedicate this dissertation to my parents, Terry and Jan, and my sisters, Zoe and Stacey. Thank you for all your visits, support and words of encouragement throughout graduate school. 6 TABLE OF CONTENTS LIST OF ILLUSTRATIONS……………………..……………………………. 9 ABSTRACT……………...………………………………………………………..... 10 INTRODUCTION………………………………………………………………… 12 PRESENT STUDY………………………………………...……………………... 22 REFERENCES………………..…………………………………………………... 31 APPENDIX A: STOCHASTIC VARIATIONS IN WATER FLOW DEPTH AND THEIR ROLE IN LONG-RUNOUT GRAVEL PROGRADATION IN SEDIMENTARY BASINS …………………………………………………………………………………………. 40 Abstract……………………………………………………………………………... 40 1. Introduction…………………………………………………………………...…. 42 2. Numerical Model Description…………………………………………………... 46 3. Numerical Modeling Results……………………………………………….….... 58 4. Discussion………………………………………………………………….…….. 67 5. Conclusions………………………………………………………………………. 74 Acknowledgements……………………………………………………………….... 76 References…………………………………………………………………. ………. 76 Tables, Figures and Figure Captions……………………………………………... 86 APPENDIX B: SIMULATING FORELAND BASIN RESPONSE TO MOUNTAIN BELT KINEMATICS AND CLIMATE CHANGE FOR THE CENTRAL ANDES: A NUMERICAL ANALYSIS OF THE CHACO FORELAND IN SOUTHERN BOLIVIA …………………………………………………………………………………………. 91 Abstract………………………………………………………………………...…… 91 7 1. Introduction……………………………………………………..……….………. 93 2. Geologic Background………………………..…………...……………………... 100 3. Numerical Model Description…………………………………………………... 103 3.1. Deformation Model……………………………………………………...….. 104 3.2. Erosion Model…………………………………………………………...….. 105 3.3. Sediment Transport Model…………………………………………….…... 106 3.4. Basin Flexure ……………………………………………………………..... 108 3.5. Numerical Modeling Methods……………………………………………... 109 4. Numerical Modeling Results…………………………………………………..... 113 4.1. End-member surface-uplift model experiment summary……….……..… 113 4.2. Constraints on foreland basin depositional rates………………………..... 117 4.3. The role of eclogite-root-foundering on surface uplift and foreland development……………………………………………………………………… 120 4.4. The role of climate change on the foreland development………………… 123 5. Discussion……………………………………………………………………..…. 125 6. Conclusions………………………………………………………………………. 133 Acknowledgements………………………………………………………………… 135 References………………………………………………………………………….. 135 Tables and Figures………………………………………………………………..... 148 APPENDIX C: QUANTIFYING THE EFFECT OF HYDROLOGIC VARIABILITY ON BEDLOAD SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS …………………………………………………………………………………………. 156 Abstract…………………………………………………………………………...… 156 1. Introduction…………………………………………………………………...…. 158 2. Analytic Solutions……………………………………………………………..… 164 2.1. Derivation of an analytic equation for long-term bedload sediment flux ……………………………………………………………………………………. 164 2.2. Derivation of the diffusivity coefficient…………………………….…….... 179 2.3. Numerical and analytic solutions for the effective discharge……..……... 181 8 3. Preliminary data analysis required for the validation of model predictions ………………………………………………………………………...…………….. 182 3.1. Climate effect on long-term bedload sediment flux………………………. 182 4. Methods of Sensitivity Studies………………………………………………….. 187 4.1. Diffusivity sensitivity studies……………………………………………...... 187 4.2. Long-term bedload sediment transport sensitivity studies………………. 189 4.3. Effective discharge return period sensitivity studies……………………... 192 5. Results of the Sensitivity Studies……………………………………………….. 193 5.1. Diffusivity sensitivity studies……………………………………………..... 193 5.2. Climate effects on long-term sediment transport………………………… 196 5.3. Climate effects on effective discharge return period…………………….. 202 6. Discussion………………………………………………………………………... 207 6.1. Diffusivity…………………………………………………………………… 207 6.2. Climate effects on sediment transport and effective discharge return period ……………………………………………………………………………………. 208 7. Conclusions………………………………………………………………………. 214 Notation…………………………………………………………………………….. 216 References………………………………………………………………………….. 218 Tables……………………………………………………………………………...... 225 Figures………………………………………………………………………………. 227 9 LIST OF ILLUSTRATIONS Figure 1: Conceptual diagrams of a gravel wedge prograding………………………… 30 Figure 2: A plot of the relationship between long-term sediment transport, discharge frequency and sediment transport rates………………………………………………… 30 10 ABSTRACT Sedimentary deposits have been broadly used to constrain past climate change and tectonic histories within mountain belts. This dissertation summarizes three studies that evaluate the effects of climate change and tectonics on sedimentary basin development. (1) The paleoslope estimation method, a method for calculating the threshold slope of a fluvial deposit, does not account for the stochastic variations in water depth in alluvial channels caused by climatic and autogenic processes. Therefore, we test the robustness of applying the paleoslope estimation method in a tectonic context. Based on our numerical modeling results, we conclude that if given sufficient time gravel can prograde long distances at regional slopes less than the minimum transport slope calculated with the paleoslope estimation method if water depth varies stochastically in time, and thus, caution should be exercised when evaluating regional slopes measured from the rock record in a tectonic context. (2) The role of crustal thickening, lithospheric delamination, and climate change in driving surface uplift in the central Andes in southern Bolivia and changes in the creation of accommodation space and depositional facies in the adjacent foreland basin has been a topic of debate over the last decade. Our numerical modeling results show that gradual rise of the Eastern Cordillera above 2-3 km prior to 22 Ma leads to sufficient sediment accommodation for the Oligocene-Miocene foreland basin stratigraphy, and thus, the Eastern Cordillera gained the majority of its modern elevation prior to 10 Ma. Also, we conclude that major changes in grain size and depositional rates are primarily controlled by mountain-belt migration (i.e., climate change and lithospheric delamination are secondary mechanisms). (3) Existing equations 11 for predicting the long-term bedload sediment flux in alluvial channels include mean discharge as a controlling variable but do not explicitly include variations in discharge through time. We develop an analytic equation for the long-term bedload sediment flux that incorporates both the mean and coefficient of variation of discharge. Our results show
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