1. Normal Faults Extensional Tectonics

2. Tectonic Settings for Extension Divergent plate motions Gravitational collapse –Over-thickened crust –Continental margins Salt Domes

3. Extensional Tectonics

4. Divergent Boundary Normal Faults, rifts

6. Continental Extension

8. Divergent Boundaries Continental Plate Separation East African Rift Valley Somali Subplate African Plate Parallel valleys; volcanoes and earthquakes.

9. Rifts Bounded by normal faults

10. Back Arc extension

12. Extension of the lithosphere 1

13. Extension of the lithosphere 2

14. Lithospheric Extension Thinning of the lithosphere Normal faulting at the surface High heat flow (rinsing of the isotherms) Thermal subsidence - > sedimentary basins

16. North Sea Extensional Basin

17. Pure shear vs. simple shear systems

18. Gravitational Collapse of Mt. Belts

19. Basin and Range Province

21. New Mountains-Active Fault –Basin and Range Province

22. Two modes of extension

24. Sandbox- Block rotation Sand above plasticine

25. Block Rotation

26. Domino block rotation in the Basin and Range

27. Listric (curved) Faults- roll over anticlines

29. Small roll-overs

30. Sedimentation during faulting Growth faulting AnimationAnimation by R. Allmendinger http://www.geo.cornell.edu/geology/faculty/RWA/movies/

31. Curved faults – Block rotation Growth Strata 3 km 0

32. Gulf of Mexico

33. Passive Margin

34. Gulf of Mexico Salt

35. Extension Above Salt Diapir

36. Transfer zone in a rift

39. Older faults rotate and become inactive New faults cross-cut them Result= large magnitude extension Successive generations of normal faults