A STRUCTURAL ANALYSIS OF SMOOTH-TOPPED CHAOTIC TERRAINS IN SOUTHERN CIRCUM-CHRYSE, MARS Jonathan Walmsley, BSc. (Hons.) Submitted in partial fulfillment of the requirements for the degree of Master of Science in Earth Sciences Faculty of Math and Science, Brock University St. Catharines, Ontario © 2019 Abstract The presence of large outflow channels on Mars shows the importance of water in shaping the surface of the planet over geologic time. Chaotic terrain has been identified as the source region for flood waters responsible for carving out many of these channels. There are still many unanswered questions regarding chaotic terrains on Mars. Using the most up to date CTX, HRSC, and MOLA coverage, DEM and TIN models were used to investigate examples of smooth-topped chaotic terrains which include Hydraotes Chaos, a crater pair in Hydraspis Chaos, Baetis Chaos, and Candor Chaos, all south of Chryse Planitia. The findings of this study suggest that the collapse of chaotic terrains is not regionally controlled. This study also suggests that the largest chaotic terrains do not require external heat sources to form. Finally, there is evidence that chaotic terrain forming events have occurred from the Middle Noachian to the Late Hesperian/Early Amazonian. ii Acknowledgements I would like to express sincere appreciation to Professor Frank Fueten for the multitude of opportunities and the endless assistance he has provided me. I would also like to thank Dr. Bob Stesky for his insights and hours of editorial work and feedback as well as my other committee members Professor Rick Cheel, and Professor Mariek Schmidt. Lastly, I would also like to thank all my friends and family which have supported and guided me through my academic career and will continue to do so for the future. iii Table of Contents Abstract .........................................................................................................................ii Acknowledgements ...................................................................................................... iii List of Figures ............................................................................................................ viii Chapter 1 ............................................................................................................. viii Chapter 2 ............................................................................................................. viii Chapter 3 ............................................................................................................. viii Chapter 4 ...............................................................................................................ix Chapter 5 ............................................................................................................... x Chapter 6 ...............................................................................................................xi Chapter 7 ...............................................................................................................xi List of Tables ............................................................................................................... xii Chapter 1 .............................................................................................................. xii Chapter 3 .............................................................................................................. xii Chapter 4 .............................................................................................................. xii Chapter 5 .............................................................................................................. xii Chapter 6 .............................................................................................................. xii Chapter 7 .............................................................................................................. xii List of Abbreviations ................................................................................................... xiii : Introduction ................................................................................................ 1 1.1 Mars ....................................................................................................................... 1 1.2 Geological and Climatic Background of Mars ........................................................ 2 1.2.1 The Dichotomy Boundary .............................................................................. 3 1.2.2 Climate Models of Early Mars ....................................................................... 4 1.2.3 Presence of a Global Ocean ......................................................................... 5 1.2.4 The Global Cryosphere ................................................................................. 7 1.3 Chaotic Terrain ...................................................................................................... 9 1.4 Formation of Martian Chaotic Terrain .................................................................. 12 1.4.1 Pressurization of Subsurface Aquifer .......................................................... 13 1.4.2 Magmatic Intrusion ...................................................................................... 14 1.4.3 Subsurface Lake Destabilization ................................................................. 15 1.4.4 Clathrates .................................................................................................... 16 iv 1.4.5 Excavation of Subsurface Volatiles ............................................................. 16 : Methodology ............................................................................................ 21 2.1 Data Source ......................................................................................................... 21 2.2 Data Display ......................................................................................................... 21 2.3 Augmented Visualization of Attitude (AVA) .......................................................... 22 2.4 Measurements ..................................................................................................... 22 : Hydraotes Chaos ..................................................................................... 26 3.1 Introduction .......................................................................................................... 26 3.2 Previous Work ...................................................................................................... 34 3.3 Methodology ........................................................................................................ 36 3.4 Results ................................................................................................................. 37 3.4.1 Orientations Obtained with AVA .................................................................. 37 3.4.2 Elevation and Distribution of Mesas ............................................................ 39 3.4.3 Orientation of Mesa Tops ............................................................................ 41 3.4.4 Distribution and Orientations of Terraces .................................................... 42 3.4.5 Evidence of Volcanism in Hydraotes ........................................................... 44 3.4.6 Calculation of Volume Loss ......................................................................... 46 3.5 Discussion ............................................................................................................ 50 3.5.1 Orientation and Distribution of Mesas ......................................................... 51 3.5.2 Sedimentation of the Basin ......................................................................... 52 3.5.3 Mesa Terraces ............................................................................................ 52 3.5.4 Presence of Cinder Cones Within Hydraotes .............................................. 53 3.5.5 Significance of Sapping Channels .............................................................. 54 3.6 Origin of Hydraotes .............................................................................................. 55 3.7 Hydraotes Chaos Formation Model ..................................................................... 56 3.7.1 Model Assumptions ..................................................................................... 57 3.7.2 Model Description ....................................................................................... 59 : Hydraspis Chaos ..................................................................................... 64 4.1 Introduction .......................................................................................................... 64 4.2 Previous Work ...................................................................................................... 69 4.3 Methodology ........................................................................................................ 70 4.4 Results ................................................................................................................. 70 v 4.4.1 Orientations Obtained with AVA .................................................................. 70 4.4.2 Elevation and Distribution of Mesas ............................................................ 73 4.4.3 Orientation of Mesa Tops ............................................................................ 74 4.4.4 Presence of Terraces and