crustal deformation (LEC 7)

Question 1

earth’s plates motions result in (3 things)

Answer 1

crustal deformation
volcanoes
earthquakes

Question 2

rocks become more ductile and less brittle at ______________ and
________________________

Answer 2

high temperatures;
high confining pressure

Question 3

what are the factors that affect deformation (4)

Answer 3

temperature
confining pressure
rock type
time (rate of deformation)

Question 4

how does temperature affect deformation

Answer 4

at high temps, rocks are closer to melting points, making the weaker, ductile

at cool temps, rocks are brittle

Question 5

how does confining pressure affect deformation

Answer 5

increased pressure in all directions makes rocks less brittle and harder to break

Question 6

how does the rock type affect deformation

Answer 6

the way a rock responds to stress is influenced by mineral composition and texture

Question 7

how does time (rate of deformation) affect deformation

Answer 7

stress applied slowly enough can accommodate ductile deformation while stress applied too quickly will fracture the rock

Question 8

strong rocks → crystalline rocks

crystalline rocks such as igneous rocks composed of minerals that have strong internal bonds tend to be brittle and fail by _______

Answer 8

fracturing (break)

Question 9

weak rocks → layered rocks

sedimentary rocks and metamorphic rocks that contain zones of weakness, such as foliation, tend to be ductile and fail by _________

Answer 9

folding (bend)

Question 10

what is a fault scarp

Answer 10

vertical displacement along faults

Question 11

what are slickensides

Answer 11

polished striated surface due to crustal blocks sliding against one another

Question 12

whats a fault Breccia

Answer 12

*loosely coherent rock that forms near the earth’s surface
*composed of broken and crushed rock fragments

Question 13

describe a dip-slip

Answer 13

*movement is parallel to the SLOPE OF THE FAULT surface
*dominant displacement is VERTICAL

Question 14

describe a strike-slip

Answer 14

*movement is parallel to the FAULT SURFACE
*dominant displacement is HORIZONTAL

Question 15

what are the three types of dip-slip faults, describe them

Answer 15

normal, reverse, thrust

normal fault: the hanging wall moves DOWN relative to the footwall, results from TENSION

reverse fault: the hanging wall moves UP relative to the footwall, results from COMPRESSION

thrust fault: like reverse fault but the hanging wall MOVES UP THE FAULT PLANE, results from COMPRESSION

Question 16

name the two types of strike-slip faults

Answer 16

right-lateral and left-lateral

Question 17

what are oblique-slip faults and what types of stress are they caused by

Answer 17

*faults that exhibit both dip-slip and strike-slip
*caused by a combination of shearing and tensional/compressional stress

Question 18

______ are fractures along which blocks have not moved (no layer displacement), result of brittle behaviour of rock

Answer 18

JOINTS!!!!!!!

Question 19

rocks are bent into a series of wave-like called _________

Answer 19

FOLDS!!!!!!

Question 20

what are the two main types of folds

Answer 20

*anticline (up-warped or arched rock layers)
*syncline (down warped or drain (troughs) of rock layers)

Question 21

in the real world, folds are generally coupled with faults and the feature is called ___________

Answer 21

monocline