1. II. Basic Techniques in Structural Geology Field measurements and mapping Terminology on faults and folds Stereographic projections From maps to cross-sections Growth Strata Fault-related folds Seismic Imaging

2. Two types of fault-related fold (drawn here assuming flexural slip folding) Fault-bend foldFault-propagation fold

3. Fault Bend Folds (FBF) =ramp anticlines -throughgoing faults - slip is conserved. -Fold amplitude is determined by the thickness above the lower hanging wall flat. -Once the fold has achieved maximum amplitude, it only grows in width. Fault-Bend Fold

4. Duplex system

5. Thrust fault hangingwall and footwall ramps and flats…

6. Fault Propagation Folds (FPF) -fault slip is not conserved. Fault displacement is taken up by folding -Fault tip is marked by a ductile ‘process zone’. -Ideally, FPF’s evolve into FBF’s Fault-Propagation Fold

7. Detachment fold (folding is always non- parallel) Fault-tip Folds Fault-propagation Fold (parallel fold) Fault-propagation fold (non-parallel fold)

8. Footwall rocks are commonly deformed into synclines ‘Drag folds’ Could also relate to fault propagation

9. Footwall syncline in the Canadian Cordillera

10. Let’s practice…

12. Primary strucure due to cross-bedding stratification. Not related to deformation

14. Describe: from: http://earth.leeds.ac.uk/learnstructure/index.htm from: http://www.stmarys.ca/academic/science/geology/structural/

15. similar fold Recumbent tight similar syncline and anticline parallel fold Upright open parallel syncline from: http://earth.leeds.ac.uk/learnstructure/index.htm from: http://www.stmarys.ca/academic/science/geology/structural/

16. try to sketch: shallowly plunging, upright, tight, similar syncline Assume fold axis plunges toward N45E

17. Example from the Argentinian Cordillera

18. What is it?

20. Fault related Folds all from: http://earth.leeds.ac.uk/learnstructure/index.htm http://earth.leeds.ac.uk/learnstructure/index.htm

21. Fault related Folds http://earth.leeds.ac.uk/learnstructure/index.htm Fault-bend Fold Fault-tip Fold

22. AB A case study of a fold and thrust belt: The North Tian Shan Piemont (Charreau et al, 2008)

25. (Suppe et al., 1997; Hubert-Ferrari et al, 2007) AB Growth strata record of Kink Band migration (Huerguosi Anticline) (Charreau et al, 2008)

26. 12 equations ex: Modeling Kinematic model (Charreau et al, 2008)

28. Bedding expected from the fault-bend fold model with growth strata Modeling dip angles Bedding measured in surface Bedding expected from the pure Fault-bend fold model (Charreau et al, 2008)

29. Long Term History of Shortening (Charreau et al, 2008)

30. Accumulation rates– Piggy back Accumulation rates- magnetostratigraphy (Charreau et al, 2008) Sedimentation History