Lesson 4: Igneous Rocks

Question 1

Formed by cooling and crystallization of magma

Answer 1

Igneous Rock

Question 2

Molten rock underground

Answer 2

Magma

Question 3

forms within crust/blow ground

surface; takes centuries – millions of years to form

Answer 3

Intrusive Igneous Rock

Question 4

forms above ground surface;

takes seconds to years to form

Answer 4

Extrusive Igneous Rock

Question 5

Molten rock above ground surface

Answer 5

Lava

Question 6

Volcanic Rocks

Answer 6

Extrusive

Question 7

Plutonic Rocks

Answer 7

Intrusive

Question 8

Magma from _____melting is the source of nearly all Igneous rocks

Answer 8

Partial

Question 9

Only certain parts of the rock melt (not all of

it) due to each component of a rock having different melting points

Answer 9

Partial Melting

Question 10

determines how far the

reaction process reaches (based on available silica) and what kind of rock it will harden into.

Answer 10

Magma Composition

Question 11

has the most SiO2

Answer 11

Felsic

Question 12

45%-55% SiO2

Answer 12

Mafic

Question 13

SiO2 < 45%

Answer 13

Ultramafic

Question 14

result to mafic rocks

Answer 14

Mafic magma

Question 15

mafic rocks will have different names depending on

where it ________

Answer 15

Crystallized

Question 16

Has low viscosity associated with (relatively) calmer

volcanic eruptions

Answer 16

Mafic magma

Question 17

fluid’s resistance to flow

Answer 17

viscosity

Question 18

show how minerals are formed as magma

cools and becomes igneous rocks.

Answer 18

Bowen’s reaction series

Question 19

branches of Bowen’s reaction series

Answer 19

Discontinuous, continuous

Question 20

Plagioclase Feldspar will have calcium rich core

and then covered with more sodium-rich Plagioclase Feldspar shell/cover.

Answer 20

Zoning

Question 21

magma formed at ~750-800°C (assuming there are still silica left)

Answer 21

Quartz, Potassium feldspar, muscovite mica

Question 22

Large part of the remaining Silica goes into

Answer 22

calcium-rich Plagioclase

Question 23

Remaining part of Silica (if there are any) transforms Olivine to

Answer 23

Pyroxene

Question 24

Mafic magma typically cools into

Answer 24

Gabbro (intusive) or basalt (extrusive)

Question 25

Intermediate magma usually cools into

Answer 25

Diorite (intrusive form) or

Andesite (extrusive form)

Question 26

Felsic magma do not have to be so hot to maintain liquid form so they crystallize/harden at

Answer 26

lower temperatures

Question 27

A felsic magam that cools starts at

Answer 27

Pyroxene and Plagioclase

Question 28

Felsic magma commonly cools into

Answer 28

Granite (intrusive form) or

Rhyolite (extrusive form)

Question 29

the _____ separates the ferromagnesian silicates on the upper right
from the non-ferromagnesian silicates on the lower left.

Answer 29

red line

Question 30

Mafic rocks tend to be darker than felsic rocks due to the

Answer 30

ferromagnesian silicates

Question 31

• Mafic rocks can have _______ ferromagnesian silicates

Answer 31

50-100%

Question 32

Intrusive rocks tend to be _______. This is because they ________under the ground, the crystals ______

Answer 32

rougher, cool slower, grow

Question 33

crystallization of minerals in certain

sequence, and separation of the ones already formed.

Answer 33

Fractional Crystallization

Question 34

settling of crystals already formed to the bottom

of a magma chamber

Answer 34

Crystal settling

Question 35

have exposed area at the surface of more than 100

km2

Answer 35

batholiths

Question 36

a pluton that is sheet-like and is parallel to the existing

layering of the underground materials.

Answer 36

sill

Question 37

similar to sill but perpendicular to the existing layering

of underground materials.

Answer 37

dyke

Question 38

sill that has expanded and pushed the rock above it.

Answer 38

LACCOLITH

Question 39

a “cylindrical” conduit (may have any cross-sectional shape)

that serves to allow movement of magma from one point to another.

Answer 39

PIPE