Chapter 4 - PREMIDTERM

Question 1

Define magma

Answer 1

molten rock + suspended crystals

Question 2

Define volcano

Answer 2

vent from which magma, solid rock debris and gases erupt

Question 3

Define lava

Answer 3

erupting magma

Question 4

Define igneous rock

Answer 4

solidified magma or lava

Question 5

define intrusive (plutonic)

Answer 5

solidified magma

Question 6

Define extrusive

Answer 6

solidified lava

Question 7

4 types of magma: (include % silica content)

Answer 7

Picritic - ultramafic (40%)
Basaltic - Mafic (50%)
Andesitic - intermediate (60%)
Rhyolitic - felsic (70%)

Question 8

Origin of basaltic, andesitic, rhyolitic magma

Answer 8

basaltic: mainly in oceanic settings
andesitic: mainly at convering plate margins
rhyolitic: mainly in continental settings

Question 9

formation of magma due to heating and or pressure decrease and or water uptake

Answer 9

• adding water causes solid to form easier

- increasing pressure and decreasing temperature forms solid

Question 10

What happens with waterloss of magma?

Answer 10

harder to solidify

Question 11

Bowens reaction series

Answer 11

Olivine ->pyroxene -> amphibole -> biotite -> potassium feldspar -> muscovite -> quartz
(as lis goes on, increasing % silica and decreasing temperature)

Question 12

Common igneous rocks

Answer 12

Extrusive:Rhyolite, andesite, basalt
Intrusive: Granite, diorite, gabbro, periodotite

Question 13

Felsic igneous rocks?

Answer 13

Rhyolite (extrusive)

Granite (intrusive)

Question 14

Intermediate igneous rock

Answer 14

Andesite(extrusive)

Diorite (intrusive)

Question 15

Mafic igneous rock

Answer 15

Basalt(extrusive)

Gabbro(intrusive)

Question 16

Ultramafic

Answer 16

periodotite

Question 17

cooling rate wrt rock

Answer 17

extrusive: rapid cooling, small grain
intrusive: slow cooling, coarse grain