Topic 4A

Question 1

difference between magma and lava

Answer 1

lava has reached earths surface, magma is in earths crust

Question 2

the mantle melts when..

Answer 2

pressure on rock is reduced ( decompression melting)
water is added to the rocks
hot rising magma comes into contact with other rocks

Question 3

where does magma form

Answer 3

convergent boundary, divergent boundary, hot spots

Question 4

what types of magma exist

Answer 4

felsic, intermediate, mafic, ultramafic

Question 5

several factors control magma composition

Answer 5

composition of source rock
partial melting
crystal settling
magma mixing
assimilation and contamination

Question 6

felsic minerals melt and crystallize at

Answer 6

low temperatures

Question 7

mafic minerals melt and crystallize at

Answer 7

high temperatures

Question 8

explain bowens reaction series

Answer 8

As minerals become unstable with a change in T. they break down to form new minerals

Question 9

magma becomes more (blank) over time

Answer 9

silica rich

Question 10

3 factors that determine how fast magma cools

Answer 10

depth of the magma
size and shape of the magma
the presence of groundwater