EARTH’S STRUCTURE AND PLATE TECTONICS Flashcards
For rocks to be deformed, they must be acted upon by stress which can be classified into three (3) basic types, what are these basic types and explain
- Compression – pushes on rocks from opposite directions which causes rocks to be shortened parallel to the stress applied
- Tension- pulls rocks from opposite directions, resulting it to become stretched/lengthened
- Shear- occurs when rocks are being pushed in an uneven manner, causing the rocks to be skewed such that different sides of a rock body slide or move in opposite directions
- Rocks near the surface of the earth are ___
elastic
all elastic materials have an ____, which is the point in which they no longer behave elastically and deformation becomes permanent.
elastic limit
- Also note that when rocks deform they often slide past one another along a fracture plane, at which point the fracture is called a ____
fault
The discontinuity between upper and lower crust
conrad discontinuity
The discontinuity between lower crust and upper mantle
mohorovicic
The discontinuity between upper and lower mantle
repetti
The discontinuity between lower mantle and outer core
gutenberg
the discontinuity between outer and inner core
Lehmann
describe crusts density and thickness
7 to 70 km thick, low density
describe mantles density and thickness
high density rocks; 2890 km; and it constitures ~83% of earths total volume
earths radius
6371 km
upper mantle depths in km
660 km
solid and rigid and is 100km thick
lithosphere
mantle contains an average of ~______ SiO2 which means it has an ultrabasic composition
~40 to 45%
The uppermost part of the mantle and the crust together constitute the relatively rigid ____, which is strong enough to rupture in response to stress
lithosphere
A discrete _______ occurs within the upper mantle at depths of ∼100 – 250km below the surface. The top of these zone marks the contact between the strong lithosphere and the weak asthenosphere
Low velocity zone (LVZ)
A discrete _______ occurs within the upper mantle at depths of ∼100 – 250km below the surface. The top of these zone marks the contact between the strong lithosphere and the weak asthenosphere
Low velocity zone (LVZ)
The asthenosphere is more _____ and flows slowly, rather than rupturing, when subjected to stress
plastic
Mineral transformations within the transition zone
Olivine > Wadleysite/Beta Spinel > Ringwoodite/Garnet > Perovskite/Periclase