Water and Wind: The Fluvial and Eolian Forces Behind the Pennsylvanian-Permian Halgaito Formation, Utah By Dawn E. Tobey Submitted in partial fulfillment of the requirements for the degree of Masters of Science at Dalhousie University Halifax, Nova Scotia September 2020 © Copyright by Dawn E. Tobey, 2020 Table Of Contents List of Tables ............................................................................................................................... v List of Figures ........................................................................................................................... vi Abstract ..................................................................................................................................... vii List of Abbreviations Used ................................................................................................. viii Acknowledgements .................................................................................................................ix Chapter 1: Introduction .......................................................................................................... 1 1.1 Statement of Problem................................................................................................................ 1 1.2 Objectives ....................................................................................................................................... 6 1.3 Contributions of the Author ................................................................................................... 6 Chapter 2: Fine-grained Dryland Rivers Reworking Loess in the Paradox Basin of Western Pangea: Halgaito Formation, Pennsylvanian- Permian of Utah ............................................................................................................... 10 2.1 Abstract ......................................................................................................................................... 10 2.2 Introduction ................................................................................................................................ 11 2.3 Geological Overview ................................................................................................................ 14 2.4 Methods ......................................................................................................................................... 17 2.5 Stratigraphic Sections, Facies, and Fossils ..................................................................... 19 2.5.1 Stratigraphic Sections ..................................................................................................... 19 2.5.2 Facies....................................................................................................................................... 20 2.5.3 Fossils ...................................................................................................................................... 31 2.5.4 Grain size comparison of eolian and fluvial siltstones ....................................... 32 ii 2.5.5 Root Traces ........................................................................................................................... 36 2.6 Channel Bodies at Study Sites .............................................................................................. 37 2.6.1 Rooster - Setting Hen ........................................................................................................ 37 2.6.2 Seven Sailors ........................................................................................................................ 42 2.6.3 Fossil Site ............................................................................................................................... 44 2.6.4 Lime Ridge ............................................................................................................................ 46 2.7 Facies Associations ................................................................................................................... 50 2.7.1 Fluvial Ribbons (FR) ......................................................................................................... 51 2.7.2 Broad Fluvial Sheets (BFS) ............................................................................................ 51 2.7.3 Confined to Unconfined Sheets (CUS) ........................................................................ 55 2.7.4 Floodplain Siltstone (FS) ................................................................................................ 56 2.7.5 Loess-Paleosol Blankets (LPB) ..................................................................................... 56 2.7.6 Lacustrine Fines (LF) ....................................................................................................... 57 2.7.7 Fluvial Paleoflow Patterns ............................................................................................. 57 2.8 Discussion .................................................................................................................................... 58 2.8.1 Fluvial-Eolian Interaction on the Halgaito Plains ............................................... 58 2.8.2 Comparison of Fluvial Architectural Styles with Facies Models .................... 61 2.8.3 Contribution of Vegetation to the Halgaito Landscape .................................... 68 2.8.4 Evolution of Fluvial and Eolian Processes during Halgaito Deposition ..... 70 2.8.5 Rivers Flowing North into the Paradox Basin ....................................................... 75 2.9 Conclusions .................................................................................................................................. 78 Chapter 3: Discussion ........................................................................................................... 80 iii 3.1 Synthesis ....................................................................................................................................... 80 3.1.1 Purpose of the Research .................................................................................................. 80 3.1.2 Modern implications ......................................................................................................... 82 3.2 Analogues ..................................................................................................................................... 83 3.2.1 Namibia. ................................................................................................................................. 83 3.2.2 Loess Plateau. ...................................................................................................................... 83 3.2.3 Volcanic ash. ........................................................................................................................ 84 3.3 Further Work .............................................................................................................................. 84 3.3.1 Paleoflow. .............................................................................................................................. 84 3.3.2 Grain Size. ............................................................................................................................. 85 3.3.3 Biostratigraphy. ................................................................................................................. 85 3.3.4 Diagenesis. ............................................................................................................................ 85 References ................................................................................................................................ 87 iv List of Tables Table 1: Facies in the Halgaito Formation in Valley of the Gods and Lime Ridge ....... 21 Table 2: Grain-size analysis of eolian and fluvial siltstones ................................................. 32 Table 3: Measured data regarding root depth, width ............................................................. 37 Table 4: Facies associations in the Halgaito Formation ......................................................... 53 Table 5: Architecture of some dryland-river deposits in the geological record .......... 64 v List of Figures Figure 1 Schematic diagram of the Paradox Basin to show main bounding uplifts ..... 2 Figure 2 Map Study sites in southeast Utah. .................................................................................. 3 Figure 3 Geological map of the region. ............................................................................................. 4 Figure 4: Terrain in the Valley of the Gods ..................................................................................... 5 Figure 5: Stratigraphic sections for the Halgaito Formation .................................................. 8 Figure 6: Sedimentary features and fossils ................................................................................. 24 Figure 7: Sedimentary features and fossils from Lime Ridge .............................................. 24 Figure 8: SEM images of representative samples ..................................................................... 26 Figure 9: Fossils ....................................................................................................................................... 28 Figure 10: Grain-size frequency curves, normalized to percentages ............................... 34 Figure 11: Two examples