earth structure and internal energy sources Flashcards
1
Q
what is the cores temperature?
A
5000 degrees
2
Q
what is primordial heat?
A
heat left over from the earths formation
3
Q
what is radiogenic heat?
A
heat produced by radio active decay of isotopes
4
Q
what is the asthenosphere?
A
semi molten (plastic-like) rock that can move slowly below lithosphere, above upper mantle
5
Q
what is the lithosphere?
A
the crust and the rigid upper section of the mantle, approx. 80-90km thick
above asthenosphere, below moho
6
Q
what is the mohorovicic discontinuity (moho)?
A
the boundary between the earths crust and mantle, marking the point where the crust begins to change composition
7
Q
what are the characteristics of oceanic lithosphere?
A
- thinner and denser
- younger
- can be renewed and destroyed (when subducted)
- faster moving
- basalt rock
8
Q
what are the characteristics of continental lithosphere?
A
- thicker and less dense
- older
- cannot be renewed or destroyed
- slower moving
- granites/sedimentary
9
Q
what are convention currents?
A
- earths core radiates heat which causes semi molten lower mantle to become less dense = rises to lithosphere
- plume of molten rock splits and spreads in 2 directions
- plates are dragged along as a result of friction
- eventually, magma cools, contracts = becomes denser than surroundings
- dense cool magma sinks towards core
- continually repeated, forming cyclic pattern
