Geomorphological Evolution of Propagating Fault Tips in Extensional and Compressional Settings This thesis is submitted in fulfilment of the requirements of the University of London for the degree of Doctor of Philosophy and the Diploma of Imperial College Alexander M. Davis Department of Earth Science and Engineering, Imperial College of Science, Technology and Medicine London. June, 2005 Research Declaration The research presented in this thesis is the work of the candidate named on the front page. Signed: AOw A. M. Davis Table of Contents Table of Contents 2 List of Figures 6 Abstract 14 Acknowledgements 15 Chapter 1: Introduction 16 1.1 Research Rationale 17 1.2 Methodology 18 1.3 Thesis Structure 19 Chapter 2: Tectonic Geomorphology 20 2.1 Introduction 20 2.1.1 Landscape Development 20 2.2 Fault Segment Evolution 23 2.2.1 Extension 23 2.2.2 Compression 26 2.3 Tectonic Geomorphology 27 2.3.1 Extension 27 2.3.2 Compression 29 2.4 Landscape Modelling 31 2.4.1 Extension 31 2.4.2 Compression 32 2.5 Geomorphic Indicators 34 2.5.1 Extension 34 2.5.2 Compression 34 2.6 Rationale 35 Chapter 3: Methodology and Data Processing 36 3.1 Introduction 36 3.2 Digital Processing Methodology 37 3.3 Data Acquisition 39 3.4 DEM generation 40 3.4.1 DEM Accuracy 42 3.5 Geo-spatial Database Compilation 42 3.6 Spatial analysis 43 3.7 Image Processing 47 2 3.8 Field Mapping 48 3.9 Interpretation 50 Chapter 4: Tectonic Geomorphology of Star Valley, Wyoming, USA: Implications for Normal Fault Segment Growth at Extensional Relays. 51 4.1 Research Rationale 51 4.1.1 Location 52 4.1.2 Previous Work 52 4.2 Regional Background 54 4.2.1 Star Valley Geological Setting 57 4.2.2 Fault Segment Geometry 59 4.2.3 Latest Quaternary Displacements 61 4.2.4 Stratigraphy 62 4.2.5 Geomorphology 62 4.3 Tectonic Geomorphology Investigation of Star Valley 64 4.3.1 Structural Geology 64 4.3.1.1 Rear Fault Segment 64 4.3.1.2 Front Fault Segment 66 4.3.1.3 Grover Relay Structure 66 4.3.1.4 Front Segment Tip 68 4.3.2 Relay Zone Stratigraphy 70 4.2.3 Front Segment Stratigraphy 72 4.4 Star Valley Geomorphology 78 4.4.1 Footwall Topography 78 4.4.2 Drainage 81 4.5 Observations of Topography and Morphology of the Grover Relay 83 4.6 Front Segment Footwall Catchments 88 4.6.1 Longitudinal Stream Profiles 88 4.6.2 Footwall Catchment Topography 90 4.6.3 Front Segment Topography 94 4.6.4 Catchment Comparisons 96 4.6.5 Rear Segment Catchments 99 4.6.6 Catchment Capture 100 4.6.7 Front Segment Topography Transition 103 4.7 Grover Relay Geomorphology 104 4.7.1 Front Segment Footwall Drainage 108 3 4.7.2 Grover Relay Drainage 108 4.7.2 Drainage evolution 110 4.8 Grover Relay Fault 113 4.8.1 Grover Relay Fault Topography 116 4.8.2 Hangingwall Footwall Topography Profiles 120 4.8.3 Transverse Fault Topography Profiles 120 4.8.4 Transverse Stream Profiles 124 4.8.5 Quaternary Grover Relay Fault Evolution 125 4.9 Front Segment Tip Topography 126 4.9.1 Willow Creek Drainage 130 4.9.2 Willow Creek Terraces 132 4.9.3 Front Fault Tip Fold Development 132 4.10 Results Summary 136 4.11 Discussion: Star Valley Landscape Evolution 136 4.12 Implications for Normal Fault Growth 141 4.13 Conclusion 143 Chapter 5: Tectonic Geomorphology of the Turpan Blind Thrust Fold Belt, Turpan Basin, Xinjiang, NW China. 144 5.1 Research Rationale 144 5.1.1 Location 145 5.1.2 Previous Work 147 5.2 Regional Background 148 5.2.1 Geological Setting 148 5.2.2 Geomorphology Setting 153 5.3 Flaming Mountain Geomorphology 154 5.4 Investigation of the Flaming Mountain Western Tip 165 5.4.1 Blind Thrust Fold Geometry 165 5.4.2 Stratigraphy 177 5.5 Water Gaps and Wind Gaps 182 5.5.1 Water Gap 1 187 5.5.2 Water Gap 2 187 5.5.3 Water Gap 3 190 5.5.4 Water Gap 4 190 5.5.5 Water Gap 5 193 5.5.6 Wind Gaps 195 4 5.5.7 Water Gap / Wind Gap Comparisons 199 5.5.8 Flaming Mountain Wind Gap Development 202 5.5.9 Water Gap / Wind Gap Transition 203 5.6 Terrain Morphology 204 5.6.1 Terrain 1: Western fold tip 204 5.6.2 Terrain 2: Minor wind gaps 206 5.6.3 Terrain: Water Gap 3-4 210 5.6.4 Terrain: Water Gap 4-5 210 5.6.5 Terrain Morphology Comparison 213 5.6.6 N-S Terrain Swath Profiles 215 5.7 Results Summary 216 5.8 Tectonic Geomorphology Model 219 5.8.1 Stage 1: Pre-Growth Bajada Fan Strata 222 5.8.2 Stage 2: Initial Fold Growth, Water Gap Development 222 5.8.3 Stage 3:Syn-Fold Growth 223 5.8.4 Stage 4: Wind Gap Development 223 5.8.5 Stage 5: Lateral Propagation and Minor Wind Gap Development 224 5.8.6 Stage 6: New Fold Tip Position 224 5.9 Discussion 225 5.9.1 Implications for Fault Segment Evolution 225 5.9.2 Comparison with Numerical Landscape Model Simulations 226 5.9.3 Fold Growth by Segmentation 227 5.10 Conclusion and Summary 229 Chapter 6: Conclusions 230 6.1 Summary of research conclusions 230 6.1.1 Major contributions of this research 230 Star Valley 230 Flaming Mountain 231 6.2 Implications for research in academia and industry 232 Chapter 7: Further Work 234 7.1 Star Valley 234 7.2 Flaming Mountain 238 Chapter 8: Bibliography 242 Appendix 1: Star Valley Data 251 Appendix 2: Turpan Fold Data 278 5 List of Figures Figure 2.1. Diagram showing drainage basin morphology, including typical drainage boundaries, in the Bogda Shan mountain range NW China. The boundaries and stream networks have been generated using an ASTER derived DEM (Davis et al., 2001). 22 Figure 2.2. Sketch graphs showing typical stream slope shapes (after Burbank and Pinter, 2000) 23 Figure 2.3. Diagram showing the geometry of an en echelon normal fault (modified after Huggins et al., 1995; Cowie et al., 2000; Crider et al., 2001). 24 Figure 2.4. a) Diagram of drainage and catchment development at extensional relays, b) drainage indicating fault propagation on the Pearce fault segment, Nevada, and c) sketch diagram of drainage indicating past position of fault tip (all diagrams modified after Jackson and Leeder, 1994). 28 Figure 2.5. Diagram of water gap and wind gap generation during blind thrust fold growth (modified after Burbank et al, 1999). 30 Figure 3.1. Diagram outlining research methodology involving data preparation, analysis and interpretation. 38 Figure 3.2. Diagram showing calculation of flow direction across a DEM based on a 3 x 3 kernel window 44 Figure 3.3. Flow diagram showing DEM hydrological spatial analysis process methodology. 45 Figure 3.4. Schematic diagram showing the relationship of longitudinal stream profile to a linear regression line fitted to catchment relief 47 Figure 3.5. Diagram showing the levelling surveying method and calculation of height along a survey traverse using a laser ranging instrument. 49 Figure 4.1. Sun-shaded regional topography image showing location of the Grand Valley Fault and Star Valley study area (Piety et al., 1992) 53 Figure 4.2. a) Overthrust Belt structure map showing location of the Absaroka Thrust, b) west — east cross section based on regional seismic line (after Piety et al., 1986) showing relationship between Absaroka Thrust and the Star Valley fault. 55 Figure 4.3. a) Cenozoic fault map of the Snake River Plain region in the Eastern Basin and Range Province, b) regional structural geology map of the Grand Valley Fault (modified after Piety et al., 1992). 56 Figure 4.4. Summary geology map of Star Valley (modified after Piety et al., 1992) 58 6 Figure 4.5. Perspective view of Star Valley with side panel showing west — east orientated cross section (modified after Ruby, 1957) latitude 42°47'30", showing half graben geometry. 59 Figure 4.6. Star Valley Fault map overlain on sun-shaded topography. Red tones indicate elevations over 2500m and blue tones around 1000m (modified after Piety et al., 1992). 60 Figure 4.7. Perspective terrain view of Star Valley, orientated north-east, showing range front, basin and mountain morphology 63 Figure 4.8. a) Plan view fault map of the Grover study area with fault segment overlain on a sun-shaded DEM image, b) perspective view of the geology draped over the DEM showing the relationship of the rock types to elevation 65 Figure 4.9. a) Annotated photomontage of the rear segment orientated N-S facing E, b) annotated photomontage of the front fault 67 Figure 4.10. a) Geological map of fault tip propagation fold. 69 Figure 4.10. b) formline cross section of Strawberry Creek and the area to the north showing bedding asymmetry and stereonet of poles to bedding indicating fold axial plunge 70 Figure 4.11. Geological map of the Grover Relay (modified after Ruby, 1957) 71 Figure 4.12. Plan view geological map of fault footwall basement and Long Spring Formation conglomerates centred on Phillips Creek. 73 Figure 4.13. Photograph of Long Spring Formation polymict conglomerate in Phillips Creek. 74 Figure 4.14. a) perspective view of the geological map overlain on digital terrain model, orientated facing north, b) Cross section of Phillips Creek.