![Strike‐Slip Fault
Strike‐slip Faults: Are faults that
have movement along strikes.
There are two types of strike slip
faults:
A] Right lateral strike‐slip fault
(dextral): Where the side opposite
the observer moves to the right.
B] Left lateral strike‐slip fault
(sinistral): Where the side
opposite the observer moves to
the left.
Note that the same sense of
movement will also be observed
from the other side of the fault.
Strike-Slip
Faults](https://image.slidesharecdn.com/faults-250511080303-36152057/85/Faults_for-Mining-Engineers-and-Geologists-pdf-15-320.jpg)
Faults_for Mining Engineers and Geologists.pdf
- 4. FAULT CLASSIFICATION AND TERMINALOGY Faults: Are fractures that have appreciable movement parallel to their plane. They produced usually be seismic activity. Understanding faults is useful in design for long-term stability of dams, bridges, buildings and power plants. The study of fault helps understand mountain building. Faults may be hundred of meters or a few centimeters in length. Their outcrop may have as knife-sharp edges or fault shear zone. Fault shear zones may consist of a serious of interleaving anastomosing brittle faults and crushed rock or of ductile shear zones composed of mylonitic rocks.
- 5. Parts of the Fault • Fault plane: Surface that the movement has taken place within the fault.On this surface the dip and strike of the fault is measured. • Hanging wall: The rock mass resting on the fault plane. • Footwall: The rock mass beneath the fault plane. • Slip: Describes the movement parallel to the fault plane. • Dip slip: Describes the up and down movement parallel to the dip direction of the fault. • Strike slip: Applies where movement is parallel to strike of the fault plane. • Oblique slip: Is a combination of strike slip and dip slip. • Net slip (true displacement): Is the total amount of motion measured parallel to the direction of motion
- 6. • Separation: The amount op apparent offset of a faulted surface, measured in specified direction. There are strike separation, dip separation, and net separation. • Heave: The horizontal component of dip separation measured perpendicular to strike of the fault. • Throw: The vertical component measured in vertical plane containing the dip.
- 8. Features on the fault surface • Grooves (parallel to the movement direction) • Growth of fibrous minerals (parallel to the movement direction) • Slickensides are the polished fault surfaces. • Small steps. All are considered a kind of lineation. They indicate the movement relative trend NW, NE … etc. Small steps may also be used to determine the movement direction and direction of movement of the opposing wall. Slicklines usually record only the last moment event on the fault.
- 9. ANDERSON FAULTS CLASSIFICATION Anderson (1942) defined three types of faults: •Normal Faults •Thrust Faults •Wrench Faults (strike slip)
- 10. Different Type of Faults
- 11. Normal Fault Normal Fault: The hanging wall has moved down relative to the footwall. Graben: consists of a block that has dropped down between two subparllel normal faults that dip towards each other. Horst : consists of two subparallel normal faults that dip away from each other so that the block between the two faults remains high. Listric: are normal faults that frequently exhibit (concave‐up) geometry so that they exhibit steep dip near surface and flatten with depth. Normal faults usually found in areas where extensional regime is present.
- 12. Normal Faults
- 13. Thrust Fault Thrust Faults: In the thrust faults the hanging wall has moved up relative to the footwall (dip angle 30º or less) Reverse Faults: Are similar to the thrust faults regarding the sense of motion but the dip angle of the fault plane is 30º or more Thrust faults usually formed in areas of comperssional regime. Thrust Fault
- 14. Thrust Faults
- 15. Strike‐Slip Fault Strike‐slip Faults: Are faults that have movement along strikes. There are two types of strike slip faults: A] Right lateral strike‐slip fault (dextral): Where the side opposite the observer moves to the right. B] Left lateral strike‐slip fault (sinistral): Where the side opposite the observer moves to the left. Note that the same sense of movement will also be observed from the other side of the fault. Strike-Slip Faults
- 16. Transform Faults Transform Faults: Are a type of strike‐slip fault (defined by Wilson 1965). They form due to the differences in motion between lithospheric plates. They are basically occur where type of plate boundary is transformed into another. Main types of transform faults are: • Ridge‐Ridge • Ridge‐Arc • Arc‐Arc
- 17. Other types of fault • en‐echelon faults: Faults that are approximately parallel one another but occur in short unconnected segments, and sometimes overlapping. • Radial faults: faults that are converge toward one point • Concentric faults: faults that are concentric to a point. • Bedding faults (bedding plane faults): follow bedding or occur parallel to the orientation of bedding planes.
- 18. CRITERIA FOR FAULTING • Repetition or omission of stratigraphic units asymmetrical repetition • Displacement of recognizable marker such as fossils, color, composition, texture ..etc.). • Truncation of structures, beds or rock units. • Occurrence of fault rocks (mylonite or cataclastic or both) • Presence of S or C structures or both, rotated porphyry clasts and other evidence of shear zone. • Abundant veins, silicification or other mineralization along fracture may indicate faulting. • Drag Units appear to be pulled into a fault during movement (usually within the drag fold and the result is thrust fault) • Reverse drag occurs along listric normal faults. • Slickensides and slickenlines along a fault surface • Topographic characteristics such as drainges that are controlled by faults and fault scarps.
- 19. First-pass interp - steep faults..…not in vogue
- 20. Low-angle thrust (detachment at depth??)
- 21. Introduction Fault-bend folding Fault-propagation folding Detachment folding Buckles Fold-thrust complexes in multilayers Trishear
- 22. Simple fault-bend fold Suppe model
- 28. Suppe fault bend folding….. But is this too simplistic a style?
- 31. Introduction Fault-bend folding Fault-propagation folding Detachment folding Buckles Fold-thrust complexes in multilayers Trishear
- 35. Fault-bend folding Fault-propagation folding Panels of constant-dip strata, folds grow by hinge migration
- 36. Test kinematic models using growth strata Growth triangles
- 37. “growth fans” rather than “growth triangles are the usual style…. So are the fault-bend models applicable?
- 38. Introduction Fault-bend folding Fault-propagation folding Detachment folding Buckles Fold-thrust complexes in multilayers Trishear
- 41. Detachment fold