structural geology Flashcards
FORCE applied to an object
stress
Rock experiences equal stress from all directions
cinfining stress
Squeezes rocks together causing folds or fractures
compressional stress
Forces pull in the opposite direction
tensional stress
Parallel forces move in opposite direction
parallel stress
Rocks deform by bending or breaking
strain
Occurs slowly, continuously, and in low stress conditions
elastic deformation
Permanent deformation when rock breaks
fracture
Rock fractures with no evidence of movement
joints
Rock fractures with evidence of movement
faults
block moves left
SINISTRAL MOTION
block moves right
DEXTRAL MOTION
Hanging wall moves downward
normal fault
Hanging wall moves upward
reverse fault
Fault plane has a low dip angle of less than 45 degrees
transverse fault
Blocks of rock or crust are bounded by normal faults
horst and graben
Drops down and creats valley
graben
rise up and become areas of higher topography
horst
Occur when horizontal strata are bent upward so that the two limbs of the fold are still horizontal
monocline
- Arch-like, or A-shaped folds that are convex-upward in shape.
- Have downward curving limbs and beds that dip down and away from the central fold axis.
anticline
Have beds that dip down and in toward the central fold axis.
syncline
The oldest rocks are exposed at the center, and rocks dip away from this central point
dome
The youngest rocks are at the center, and the rocks dip inward towards the center
basin
If the hinge is horizontal
non plunging fold
the hinge is tilted
plunging fold
the response of the lithosphere depending on its strength or stress fields causing the strain.
lithosphere rheology
Deformation up to some yield strength (the elastic limit) is non-permanent
elastic behavior
resist deformation up to a certain yield stress, or yield strength
plastic behavior
Viscosity measures resistance to deformation, specifically that caused by flow.
viscous behavior
This the compass direction of the line that form at the intersection of the plane and an imaginary horizontal plane
strike
This is the angle at which plane is inclined relative to the horizontal
dip
the process of mountain-building, typically through the tectonic forces and movements of the Earth’ s lithosphere.
oreogenesis
