a well prepared presentation on the topic of geological faults describing geometric and genetic classification and all other types of faults

1. FAULTS
&
CRITERIA FOR FAULTING

2. GROUP MEMBERS
•ALI IMTIAZ
•MUNEEB-UR-REHMAN
•UMER ABDUR REHMAN

3. WHAT IS A FAULT?
A fault is a fracture, along which a
rock on one side move relative to the
rock on other side.
The real question is,
What is a fracture?

4. FAULT TERMINOLOGIES
• Fault plane
Planer surface along which rocks on opposite
side move.
• The walls:
1) Hanging wall
2) Foot wall
• Slips
1) strike slip
2) dip slip
3) oblique slip

5. NET SLIP
• Net slip is measured by the vector
that traces the displacement between
originally adjacent points.
• 3 components:
1-net slip
2- dip slip
3- strike slip

6. TYPES OF SLIPS

7. THROW & HEAVE
Throw:
Horizontal component of
seperation.
Heave:
Vertical component of seperation.

8. GENETIC CLASSIFICATION OF
FAULTS
1) Normal Faults
2) Thrust Faults
3) strike slip Faults
4) Net slip Faults

9. NORMAL FAULTS
• Hanging wall moves downward w.r.t.
foot wall.
• Extensional environment

10. NORMAL FAULTS
• Also known as gravity faults by some geologist
• A detechmant fault is a special category of low
angle normal faults due to downhill sliding of rocks
from an uplifted region.

12. EXAMPLE
• Amorgos fault:
Location: greece
Length: >100km
Type: normal fault
Status: active

13. THRUST FAULT
• Thrust fault is a fault along which the
hanging wall moves up relative to foot wall
• Further classified into 3 types:
• Reverse fault: is thrust that dips > 45’
• Thrust: that dips <45’
• Overthrust: that dips < 10’ and has large net-
slip,
For example,
Longmen shan fault
Location: china
Status: active

14. REVERSE FAULT
• Hanging wall moves upward at >45
degree angle.
• Compressional environment.

15. STRIKE SLIP FAULTS
• Also called as wrench faults.
• walls slide pass each other or displacement
parallel to the strike.
• Further classify into 2 types:
• 1-Sinistral:Left lateral strike-slip fault (sinistral): Where
the side opposite the observer moves to the left.
• 2-dextral: Right lateral strike-slip fault (dextral): Where
the side opposite the observer moves to the right
Example is: an Andreas Fault..

17. TEAR FAULTS
• Tear faults can be be defined as relatively small-scale,
local strike-slip faults that are associated with other
structures such as folds, thrust faults and normal faults
(Twiss and Moore 1992). The tear faults may be a result
of drastic lateral changes when the thrust front advances
or by differential shortening of the thrustal sheet. For
example as one part of the thrust sheet is shortened by
faulting and the other is shortened by folding, the
displacement is taken up by the tear fault. The
Jacksboro fault in the Appalachians is a good example
of a tear fault that segments the Pine Mountain Thrust
Belt (Twiss and Moores 1992).

18. TEAR FAULTS

19. STRIKE SLIP FAULTS
• It is also classified into transform faults and transcurrent
faults. Transform faults end at the junction of another
plate boundary or fault type, while transcurrent faults die
out without a junction. In addition, transform faults have
equal deformation across the entire fault line, while
transcurrent faults have greater displacement in the
middle of the fault zone and less on the margins. Finally,
transform faults can form a tectonic plate boundary,
while transcurrent faults cannot.

20. TRANSFORM & TRANSCURRENT
FAULTS

21. GEOMETRICAL CLASSIFICATION
i- rake of net slip
ii- attitude of fault w.r.t adjacent
beds.
iii- fault pattern
iv- apparent movement
v- dip of the fault

22. BASED ON RAKE OF NET SLIP

23. BASED ON RAKE OF NET SLIP
• Strike-slip Fault: in which netslip is parallel to strike of
fault. i.e strike=netslip and there is no dip slip.
• Dip-slip fault: in which netslip is up or down the dip of
the fault i.e dipslip=netslip and there is no strikeslip
component, rake of netslip=90’
• Diagonal-slip Fault: in which netslip is diagonally up or
down the fault plane. There is bothe strike slip and
dipslip component, rake of netslip>0’ but <90’

24. BASED ON ATTITUDE OF FAULT
REALATIVE TO ATTITUDE OF
ADJACENT BEDS
• Strike fault: that essentially parallel to the strike of
the adjacent rocks.

25. BASED ON ATTITUDE OF FAULT
REALATIVE TO ATTITUDE OF
ADJACENT BEDS
• Bedding Fault: is variety of strike fault that is
parallel to the bedding

26. BASED ON ATTITUDE OF FAULT
REALATIVE TO ATTITUDE OF
ADJACENT BEDS
• Dip Fault: strikes essentialy
parallel to the direction of
dip of the adjacent beds.

27. BASED ON ATTITUDE OF FAULT
REALATIVE TO ATTITUDE OF
ADJACENT BEDS
• Oblique/diagonal Fault: that strikes obliquely or
diagonally to the strike of the adjacent rocks.

28. OBLIQUE SLIP FAULT
TRANSTENSION
FAULT
TRANSPRESSION
FAULT

29. BASED ON ATTITUDE OF FAULT
REALATIVE TO ATTITUDE OF
ADJACENT BEDS
• Longitudinal Fault: is parallel to the strikes of the
regional structure.
• Transverse Fault: strikes perpendicularly or
diagonally to the strike of the regional structure.

30. LONGITUDANAL & TRANSVERSE
FAULTS

31. BASED ON FAULT PATTERN
• Parallel Faults: set of faults having same strike and
dip. (dip may be change).
• En echelon fault: are relatively short faults that
overlap each other.

32. BASED ON FAULT PATTERN
• Peripheral Faults: are circular or arcuate faults that
bounds a circular area.
• Radial Faults: belongs to a system of faults that
radiates out from a point.

34. BASED ON VALUE OF DIP OF
FAULT
This is based on the angle of the dip
of the fault.
a- high angle faults: that dips greater
than 45’
b- low angle faults: that dips less
than 45’

35. BASED UPON APPARENT
MOVEMENT
• Apparent Normal Fault: in which hanging wall
appears to have gone downward relative to
footwall.
• Apparent Thrust Fault: in which hanging wall
appears to have gone upward relative to footwall.

36. SYNTHETIC AND ANTITHETIC
FAULTS
• Synthetic and antithetic faults are terms used to
describe minor faults associated with a major fault.
Synthetic faults dip in the same direction as the
major fault while the antithetic faults dip in the
opposite direction. These faults may be
accompanied by rollover anticlines (e.g. the Niger
Delta Structural Style).

37. LISTRIC FAULTS
• listric faults can be defined as curved normal faults
in which the fault surface in concave upwards; its
dip decreases with depth. These faults also occur in
extension zones where there is a main detachment
fracture following a curved path rather than a planar
path.

38. DETACHMENT FAULTS
• Detachment faulting is associated with large-
scale extensional tectonics. Detachment faults often
have very large displacements (tens of km)

39. COMPLETE PICTURE OF FAULTS

40. CRITERIA FOR FAULTING
• Several criteria are there, some of them
are discussed here:
1- discontinuity of structure
2- repetition or omission of strata
3- feature/characteristics of fault plane
4- silicification and mineralization
5- sudden change in sedimentary facies
6- physiographic data

41. DISCONTINUITY OF STRATA

42. REPETITION OR OMISSION OF
STRATA

43. FEATURE OF FAULT PLANE
• Following features can be seen in a
fault:
1- Slickensides
2- Gouge
3- Breccia
4- Mylonite

44. SLICKENSIDES

45. GOUGE, BRECCIA & MYLONITE
• These are identified on the basis of size and
percentage of matrix given by:
Gouge : <0.1mm (30% matrix)
Breccia : >0.5 to <1mm (30% matrix)
Megabreccia: >0.5 mm (30% matrix)
Microbreccia <1mm (30% matrix)
Mylonite: <50 micrometer (50% matrix)

46. SILICIFICATION AND
MINERALIZATION
• Silicification is the process in which
a rock’s part is replaced due to
solution passage from the fractures.
• Due to different type of solution
precipetation, mineralization may also
found in faults.

50. SUDDEN CHANGE IN
SEDIMENTARY FACIES
• By horizontal displacement, different
sedimentary facies of the same age
come in contact with each other.

51. PHYSIOGRAPHIC DATA
• Scarp: features that show a sudden
increase in slope and indicate the
presence of faults.

52. IMPORTANCE OF FAULTS
• This trap is formed by the movement
of permeable and impermeable layers of rock along
a fault line. The permeable reservoir rock faults
such that it is now adjacent to an impermeable rock,
preventing hydrocarbons from further migration.

53. MAJOR FAULTS OF PAKISTAN
• 1. Main Karakoram Thrust
• 2. Raikot Fault
• 3. Panjal-Khairabad Thrust
• 4. Riasi Thrust
• 5. Salt Range Thrust
• 6. Bannu Fault
• 7. Chaman Transform Fault
• 8. Quetta-Chiltan Fault
• 9. Pab Fault

55. THANK YOU
PRESENTED BY: MUNEEB UR
REHMAN
QAU ISLAMABAD
MUNEEBURREHMAN424@YAHOO.C
OM