STRUCTURAL GEOLOGY HATCHER 9 Flashcards
Plane of dispplacement or the actual movement surface
Fault plane
Rock mass resting on the fault plane
Hanging wall
Rock mass beneath the fault plane
Footwall
Movement parallel to the plane surface
Slip
the total amount of motion measured parallel to the direction of motion
Net Slip ot True Displacement
The net displacement of the combined Strike and Dip Slip
Rake
Heave and Throw are componets of
Dip Slip
Heave corresponds to
the horizontal component normal to the strike
Throw Corresponds to
the Vertical component
Polished fault SURFACES
Slickensides
STRIATIONS on such surfaces
Slickenlines
Aligned FIBROUS MINERALS on a movement surface
Slickenfibers
What are these three and their implication?
Lineations indicates relative movement along a surface
A british geologist who classified faults
Ernest Anderson
HW moved down relative to FW
Normal Fault
two normal fault dipping TOWARDS ONE ANOTHER produces
Graben - dropped down block
Two normal faults dipping away from each other
Horst - Up thrown block
Normal faults that exhibit concave up geometry that is STEEP plane near the surface and gentler within depths
Listric Normal Fault or Lag
Type of fault produced in conjuction with Listric Fault
Rollover Anticline
HW moved up relative to FW
Reverse and Thrust Faults
Age of Reverse Faults
45deg or greater (>45)
Age of Thrust Faults
30deg or less (<30)
Strike slip fault that compensates differences in Motion between plates
Transform Faults
faults that are approximately parallel to one another unconnected but sometimes overlap
En Enchelon Fault
faults that that converge toward a single point
Radial fault
Faults that are concentric around a single point
Concentraic Fault
Fault: Assymetric Repetion= _______: Symmetric repetition
Fold
produced along a fault when units appeared to be pulled INTO a Fault during movement
Drag (Eto ung line ng bedding magbebend towards the plane)
In a thrust fault, a drag in the hanggin wall would look like
Being pulled down dip
Drag in listric faults where layering appears to have been darg down dop parallel to the movement along the fault
Reverse drag
Is slickensides and slickenlines enough to prove significant faulting?
No, they may forrm on bedding surfaces during folding or may actaully form on joints that have small shear displacement
A topographic surface whch is offset by DIP SLIP motion along a fault and DIRECTLY INDICATE the MOVEMENT SENSE of a fault
Fault Scarp
When such topographic surface has been eroded along the fault and have been lowered to the topographic surface which removes anuu resistant hanging wall and does not directly give the movement sense
Fault Line Scarp
A fault line scarp in which erosion preserves the movement semse
Resequent Fault Line scarp
A fault line scarp that have been eroded and provides a fault movement sense
Obsequent Fault Line Scarp
Primary Criteria
Repetition and Omission of Strat Units
Displacement of recognizable markers
Truncation on of earlier structure
The observation that maximum principal stress bisects acute angle between the conjugate shear planes of the stress elipsoid
Hartman’s Rule
Formula for acute angle between shear planes
angle = 45 - angle of internal friction/2
