Rock Deformation Flashcards
Explain the deformation process
all rocks will undergo elastic deformation until they reached the elastic limit where they’ll undergo ductile deformation until they fracture
Differentiate stress and strain
stress is the force we apply on a rock body (not uniform) while strain is the product or response to the stress
Classification of stress:
Compressional
Tensional
Shearing
Compressional - squeeze
Tensional - pulling apart
Shearing - slippage/translation
Differentiate strike from dip
strike is the bearing measurement made by the contact of the geologic feature to the horizontal plane while dip is the angle of tilt between the geologic feature to the surface
In ductile deformation, what type of stress is present and what is the resulting strain?
Ductile deformation: compressional stress causes rocks to be deformed into series of wrinkles or folds
Differentiate axial plane from fold axis
Axial plane is the imaginary plane that divides the fold into two limbs while the fold axis is the line of intersection between the axial plane and the beds in the fold
What is a limb?
it corresponds to the two sides of an anticline or syncline
3 types of fold:
symmetrical - vertical axial plane
asymmetrical - some beds dip more steeply than others
overturned - tilted beyond the vertical
4 types of fold nomenclature
anticline
syncline
monocline
overturned
In brittle deformation, differentiate fault and fracture
fracture is a break in rock while fault is a fracture along which an appreciable displacement has occurred.
Classification of fault:
dip slip - normal, reverse, thrust
strike slip - sinistral, dextral
oblique slip
In dip slip fault:
normal
reverse
thrust
normal - tensional (HW goes down, FW goes up)
reverse - compressional (HW goes up, FW goes down)
thrust - reverse fault which dips less than 45 degrees
In strike slip fault:
sinistral
dextral
sinistral - left
dextral - right
