Deformations Flashcards
Rocks bend, break, or flow in response to stress
deformation
products of deformation
folds
faults
joints
foliation
causes of deformation
horizontal movements of plates relative to one another
Force applied per unit area producing deformation
stress
pushes rock together
compression
stretches rock
tension
can cause masses of rock to slip
shearing
cracking and breaking of rocks
brittle deformation
shape change without visible breaking
Ductile deformation
structures produced by brittle deformation
joints and faults
no appreciable displacement
joints
appreciable displacement
faults
tectonic or non-tectonic
joints
tectonic
faults
Parts of a fault
fault plane
fault trace
footwall
hanging wall
movement is parallel to dip or inclination
dip slip faults
hanging wall moves down relative to footwal
normal fault
hanging wall moves up relative to footwall
Reverse fault
movement is horizontal and parallel to strike
Strike slip faults
aka sinistral fault; facing the fault line, the opposite block moves to the left
left lateral strike slip fault
aka dextral fault; facing the fault line, the opposite block moves to the right
right lateral strike slip fault
movement is both strike slip and dip slip
oblique slip faults
what structures are produced by ductile deformation
folds
basins
domes
curved structures formed due to horizontal or vertical compressional stress
folds
layered rocks are bent upward into arches, oldest layer is at the center
anticline
layered rocks are bent downward intro troughs, youngest layer is at the center
syncline
sides of a fold
limbs
imaginary surface that divides the fold
axial plane
intersection of the axial plane with the rock layers
fold axis
common in interiors of plates due to upward force of rising material or downward force of sinking material
circular structures
importance of folds
sites of petroleum deposits
host natural gas deposits
importance of faults
sites of mineralization
host mineralized deposits
future earthquake indicators
means of releasing tectonic stress
