Crust key terms Flashcards
1
Q
felsic
A
- light colour minerals
- high in silica rocks
- felspars
- crystallise at lower temperatures
2
Q
Mafic
A
- Dark colour minerals
- rich in magnesium and iron
- cystalize at higher temperatures
- olivine, peridotities
3
Q
homogenous
A
orderly minerals
4
Q
mineral
A
building block or rock with unique chemical composition
5
Q
coherent
A
held together with interlocking crystal, or cemented together
6
Q
compound
A
made up of two or more elements
7
Q
intursive crystals
A
crystallises at depth inside earth (in magma)
- mafic
- bigger crystals, cools slower
8
Q
extrusive crystals
A
lava crystallisation outside the earth
- smaller crystals, cools rapidly
9
Q
basic
A
igneous rock, low silica, mafic side
- gabbros and basalt
- generally intrusive, slow cooling
10
Q
lithosphere
A
he hard, rigid plates and upper part of the mantle
11
Q
asthenosphere
A
the region below the lithosphere 85 to several 100km thick, very viscous, ductile and mechanically weak.
12
Q
differentiation of the crust
A
- Starts with partial melting of the mantle
- Magma works its way upwards towards
the surface - Different minerals crystallise at different temperatures and pressures
- Remaining melt contains concentrations of minerals and volatiles that crystallise at lower temperatures and pressures
- deeper the more mafic, higher up (crust) silica based, periditites lower down
13
Q
Peridotities
A
made up of olivine and pyroxine
14
Q
key basic rocks
A
gabbros, dolerites, basalts
- dark colours,
- minerals within; pyroxene, plagioclase felspar, small amounts of olivine
15
Q
gabbros
A
- coarsely crystalline, slowest
- intrusive
