1. Gallery
A selection of seismic profiles illustrating brittle and ductile deformation structures

2. Normal Fault
The curved shape makes this a listric fault.
A listric shape is very common.
Click to show interpretation

3. Click to show interpretation⇃ ↾
Reverse fault
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4. Faults occur in complex patterns, this is block faulting
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5. Click to show interpretation
Step faulting
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6. Stepped faults or monoclines?
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7. Click to show interpretation
Unconformity
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8. Complex folding can be caused by the migration of salt.
Salt deformation offshore France
The salt body is coloured black
Image from the Virtual seismic Atlas Author: TGS-Nopec

9. Salt dome Gulf of Mexico
Extreme deformation caused by very large quantities of low density salt migrating towards the surface.
Image from the Virtual seismic Atlas Author: Bruce Trudgill

10. Salt dome Gulf of Mexico
Seismic data poor here due to the salt (seismic waves do not get reflected back to the surface)
Salt diapir has low density and moves towards the surface
Salt dome Gulf of Mexico
Image from the Virtual seismic Atlas Author: Bruce Trudgill

11. This is a thrust zone from offshore Namibia
65 km
5000 msec TWT
This is a thrust zone from offshore Namibia
It is a very large structure
The next slide shows a zoomed view
Image from the Virtual seismic Atlas Author: Rob Butler

12. Thrust offshore Namibia
Image from the Virtual seismic Atlas Author: Rob Butler

13. This map shows the location of Namibia.
Thrusts are low angle reverse faults commonly associated with mountain building (orogenies).
Mountain building is associated with plate collisions.
This map shows the position of the major plates.
Namibia is not near any colliding plates.
BUT - it is near a place where the continental crust meets oceanic crust (passive margin).
What could be the mechanism for this thrust zone?
It is driven by gravity