Exam 2 part 1

Question 1

What are Felsic and Mafic rocks and what do the terms mean?

Answer 1

Igneous Rocks, Felsic and Mafic are terms to describe what they are made of

Question 2

What does felsic and mafic mean in terms of composition?

Answer 2

It means that felsic rocks have more silica in them while mafic rocks do not.

Question 3

What influences Magma behavior?

Answer 3

Silica content

Question 4

Generally, what silica content does Granitic Magma have and what consistency does it have?

Answer 4

It generally has a high silica content and it’s consistency is also viscous, meaning it has high resistance to internal flow

Question 5

Generally, what silica content does Basaltic Magma have and what consistency does it have?

Answer 5

It generally has a low silica content and it’s consistency isn’t viscous, meaning it has low resistance to internal flow

Question 6

What does intermediate mean for felsic and mafic rocks?

Answer 6

It means that it’s in the middle between felsic and mafic rocks in terms of it’s silica content.

Question 7

What kind of rock is Phaneritic and where can you find it?

Answer 7

It’s a coarse grained igneous rock and you can find it from cooled magma underground

Question 8

What kind of rock is Aphantitic and where can you find it?

Answer 8

It’s a fine grained igneous rock and you can find it from cooled magma above around.

Question 9

What is the name of a Felsic Phaneritic rock?

Answer 9

Granite

Question 10

What is the name of a Felsic Aphanitic

Answer 10

Rhyolite

Question 11

What are Obsidian and Pumice and what is the difference between them?

Answer 11

They are both igneous rocks with glassy texture, but obsidian is compact and dark in color while Pumice is frothy and light in color

Question 12

What are Andesite and Diorite and what is the difference between them?

Answer 12

They are both igneous rocks but Andesite has a volcanic origin and is fine grained and Diorite has a Plutonic origin and is coarse grained

Question 13

What is Basalt and what is it made of?

Answer 13

Volcanic igneous rock with a amphanic texture. Made of calcium-rich plagioclase feldspar and pyroxene.

Question 14

What is the most common extrusive igneous rock?

Answer 14

Basalt

Question 15

What is Gabbo and what is an equivalent of?

Answer 15

Plutonic igneous rock with a Phanetitic texture. Equivelant of Basalt meaning it’s also made of calcium rich plagioclase feldspar and pyroxene

Question 16

Which rock is a significant percent of the ocean floor?

Answer 16

Gabbo

Question 17

What are pyroclastic rocks?

Answer 17

Fragments ejected during a volcanic eruption

Question 18

What is tuff?

Answer 18

Ash-sized fragments

Question 19

What is Volcanic Breccia?

Answer 19

Fragments bigger than ash

Question 20

What is tuff made of?

Answer 20

It can be made of anything that’s in the lava flow. Tuff is just a fragment size

Question 21

How does heat work in the crust?

Answer 21

It gets warmer, 20 celcius to 30 celcius per kilometer

Question 22

If rocks are near their melting point, where are they usually?

Answer 22

In the lower crust and upper mantle

Question 23

When you have a lot of pressure on a rock what does it do?

Answer 23

It increases the rock’s melting point in temperature

Question 24

What happens if you decrease the pressure of a rock that has had a lot of pressure on it?

Answer 24

It will melt because of decompression melting

Question 25

Where does decompression melting occur?

Answer 25

It occurs in the asthenosphere

Question 26

What are volatiles?

Answer 26

They are primarily water.

Question 27

What do volatiles do?

Answer 27

They cause rocks to melt at a lower temperature

Question 28

How do minerals crystallize?

Answer 28

they crystallize in systematic fashion based on their melting points

Question 29

Does anything change in magma when it crystallizes?

Answer 29

Yes, the composition of the liquid portion of magma makes continuous changes through out crystallization

Question 30

What are the 3 processes that can change a magma’s composition?

Answer 30

1) Magmatic Differentiation
2) Assimilation
3) Magma mixing

Question 31

What is Magmatic Differentiation?

Answer 31

This is what crystal settling is. Where earlier formed crystals in the magma settle at the bottom of the chamber because they are heavier.

Question 32

What is Assimilation?

Answer 32

A change in the magma’s composition by adding some of the rock that surrounds the magma.

Question 33

What is magma mixing?

Answer 33

When two chemically distinct magmas produce a composition quite different from either original magma

Question 34

What is partial melting

Answer 34

It’s when the melting of rocks is incomplete

Question 35

Where do most basaltic magma originate from?

Answer 35

Most originate from the partial melting of ultra mafic rock in the mantle at oceanic ridges

Question 36

What kind of magma is common at the Earth’s surface?

Answer 36

Large out pourings of basaltic magma is common at the Earth’s surface

Question 37

What are the 2 ways that Andestic magma is formed?

Answer 37

1) It’s produced by the interaction of basaltic magma and silica-rich rock in the crust.
2) Magmatic Differentiation

Question 38

How is granitic magma formed?

Answer 38

They form as the end product of crystallizations of andesitic magma.

Question 39

Which magma is the most viscous? Can this magma reach the surface?

Answer 39

Granitic magma, they tend to lose their mobility before reaching the surface.

Question 40

What kind of structures do granitic magma produce?

Answer 40

They tend to produce large plutonic structures.