Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geology > Igneous Rocks > Flashcards

Igneous Rocks Flashcards

1
Q

Igneous activity occurs in four settings:

A
  1. isolated mantle plume hot spots
  2. volcanic arcs bordering deep ocean trenches
  3. mid-ocean ridges
  4. continental rifts.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where does most igneous activity on planet Earth take place?

A

Mid-ocean ridges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is Decompression melting?

A

Rocks that would otherwise melt are kept solid by high pressure. When the pressure decreases, melting ensues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

These hot spots are a mix of mafic and felsic (basalt and rhyolite)

A

Continental hot spots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Oceanic hot spots are:

A

mafic (basaltic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The base of the crust is hot enough

to melt rock. Why doesn’t the rock melt?

A

Because the pressure is too high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When does pressure drop?

A

When the rock is carried to shallower depths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When does Flux Melting occur?

A

Flux melting occurs when volatiles are introduced into the hot mantle. Volatiles lower the melting T of a hot rock.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is heat-transfer melting?

A

When rising magma carries mantle heat with it. This raises the T in nearby crustal rock, which melts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the three components of magma?

A

Solids
liquids (composed of Si and O)
gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is magma movement governed?

A

By viscosity, which is affected by temperature, volatile content, and % silica content.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Magma with less SiO2 is…

A

mafic (low viscosity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Mama with more SiO2 is…

A

Felsic (high viscosity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

There are two types of igneous rock environments

A
  1. Intrusive

2. Extrusive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In extrusive settings…

A
  • Rock cools fast
  • at/near the surface
  • crystals do not have time to grow large
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In intrusive settings…

A
  • Rock cools slow
  • at depth
  • crystallization occurs over a long period of time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

These rocks are usually more resistant to erosion, and often stand high on the landscape.

A

Intrusive rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are Plutons? What do they form?

A

Large blobs of magma that cool deep underground. They form batholiths.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are batholiths?

A

made of immense volumes of intrusive rock. Batholiths often remain as evidence of fossil subduction zones.

20
Q

What are sills?

A

a tabular sheet of igneous rock intruded between and parallel with the existing strata.

21
Q

What are continental rifts?

A

places where continental lithosphere is being faulted, stretched, and thinned.

22
Q

Why are mafic magmas more likely to be extrusive?

A
  • higher temperature
  • lower viscosity
  • lower SiO2 content
23
Q

What is a common feature of extrusive settings?

A

Lava flows

24
Q

What are LIPs?

A

Large Igneous Provinces - unusually large outpourings

of magma that have appeared over time

25
Q

What are Xenoliths?

A

chunks of wall rock incorporated into the magma.

26
Q

What is fractional crystallization?

A

crystals that form early settle out of the melt by gravity. The composition of the remaining melt changes as a result.

27
Q

Who discovered that fractional crystallization leads to changes in magma composition?

A

N.L. Bowen

28
Q

What minerals crystallize first? at what temperature?

A

Mafic minerals crystallize first at high temperatures (Olivine)

29
Q

What are the last minerals to crystallize? at what temperature?

A

Quartz, muscovite, and K-feldspar. At Low temperatures

30
Q

What are the 4 types of magmas? what are they based on?

A
  1. Felsic 2. Intermediate 3. Mafic 4. Ultramafic

Based on % silica content

31
Q

Felsic magma has (density, temperature, SiO2 content)

A

LOW density, LOW temperature, HIGH SiO2 content

32
Q

Mafic magma has (density, temperature, SiO2 content)

A

HIGH density, HIGH temperature, LOW SiO2 content

33
Q

Magma composition is determined by a number of factors. The most important is…

A

The composition of the initial rock

34
Q

A mantle source will produce what kind of magma?

A

Mafic and ultramafic

35
Q

A crustal source will produce what kind of magma?

A

Mafic, intermediate, and felsic magmas

36
Q

What kind of minerals melt first?

A

Silica rich minerals melt first

37
Q

Complete melting of xenoliths into the magma is called?

A

Assimilation

38
Q

Igneous rocks are described by

A

Color and texture

39
Q

Texture includes these three things

A

Interlocking (crystalline), Fragmental, and Glassy

40
Q

What texture is used to describe coarse and fine?

A

A porphyritic texture

41
Q

What kind of crystals are fine-grained and grow fast?

A

Aphanitic

42
Q

Phaneritic crystals…

A

develop by cooling slow and are coarse-grained

43
Q

Phaneritic crystals are usually found in….

Aphanitic crystals are usually found in…

A

Intrusive settings

Extrusive settings

44
Q

Name 4 ways to describe rock composition

A
  1. Basaltic
  2. Diotoric
  3. Rhyolitic
  4. Peridotitic
45
Q

Si, Na, K and Al are all associated with

A

Felsic composition

46
Q

What is pressure relief melting?

A

What causes hot rock to melt when it convects upwards

Geology (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions