Brainscape's Knowledge GenomeTM

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


See full index

GEO 101 > igneous rocks (4) > Flashcards

igneous rocks (4) Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards Psychology 101 flashcards Chemistry 101 flashcards Biology 101 flashcards Organic Chemistry 101 flashcards Sociology 101 flashcards
1
Q

Magma

A

A molten rock found at depth, including any dissolved gases and crystals

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

Igneous Rock

A

Rock formed from the crystallization of magma

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

Lava

A

Magma that reaches Earth’s surface

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

Melt

A

The liquid portion of magma excluding the solid crystals

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

Volatiles

A

Gaseous components of magma dissolved in the melt. Volatiles will readily vaporize (form a gas) at surface pressures

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

Crystallization

A

The formation and growth of a crystalline solid from a liquid or gas

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

Intrusive Igneous Rock

A

Igneous rock that formed below Earth’s surface

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

Plutonic Rock

A

Igneous that form at depth. Named after Pluto, the god of the lower world in classical mythology

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

Extrusive Igneous Rock

A

Igneous rock formed when magma solidifies at Earth’s surface

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

List and describe the three components of magma.

A

Liquid- melt
Solid- crystals of silicate minerals
Gas- volatiles (H2O, CO2, SO2)

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

Igneous rocks are composed mainly of which group of minerals?

A

Silicate minerals

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

How do light-colored igneous rocks differ in composition from dark-colored igneous rocks?

A

Light-colored are felsic or granitic (lots of silica) (low temperature) (viscous)
Dark-colored are mafia or basaltic (dense)

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

List the four basic compositional groups of igneous rocks, in order from highest silica content to lowest silica content.

A

Felsic
Intermediate
Mafic
Ultramafic

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

Texture

A

The size, shape, and distribution of the particles that collectively constitute a rock

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

What are the three factors that influence the textures of igneous rocks?

A

The rate at which molten rock cools
The amount of silica present in the magma
The amount of dissolved gases in the magma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Aphanitic/Fine-Grained

A

A texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished without the aid of a microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Porphyritic Texture

A

An igneous rock texture characterized by two distinctively different crystal sizes. The larger crystals are called phenocrysts, whereas the matrix of smaller crystals is termed the groundmass.

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

Phenocryst

A

A conspicuously crystal embedded in a matrix of finer-grained crystals

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

Groundmass

A

The matrix of smaller crystals within an igneous rock that has porphyritic texture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Porphyry

A

An igneous rock that has a porphyritic texture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Vesicular Texture

A

A term applied to aphanitic igneous rocks that contain many small cavities called vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Glassy Texture

A

A term used to describe the texture of certain igneous rocks, such as obsidian, that contain no crystals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Fragmental/Pyroclastic Texture

A

An igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent volcanic eruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Pegmatite

A

A very coarse-grained igneous rock (typically granite) commonly found as a dike associated with a large mass of plutonic rock that has smaller crystals. Crystallization in a water-rich environment is believed to be responsible for the very large crystals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Pegmatitic Texture

A

A texture of igneous rocks in which the interlocking crystals are all larger than one centimeter in diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does the rate of cooling influence crystal size?

A

The slower the magma cools the bigger the crystal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does a porphyritic texture indicate about the cooling history of an igneous rock?

A

2 stage cooling

28
Q

Granite

A

An abundant, course-grained igneous rock composed of about 10-20% quartz and 50% potassium feldspar. Granite is used as a building material.

29
Q

Rhyolite

A

The fine-grained equivalent of the igneous rock granite, composed primarily of the light-colored silicates

30
Q

Obsidian

A

A volcanic glass of felsic composition

31
Q

Pumice

A

A light-colored, glassy vesicular rock commonly having a granitic composition

32
Q

Andesite

A

A gray, fine-grained igneous rock, primarily of volcanic origin and commonly exhibiting a porphyritic texture

33
Q

Diorite

A

A coarse-grained, intrusive igneous rock primarily composed of plagioclase feldspar and amphibole minerals

34
Q

Basalt

A

A fine-grained igneous rock of magic composition

35
Q

Gabbro

A

A dark-green to black intrusive igneous rock composed of dark silicate minerals. Gabbro makes up a significant percentage of oceanic crust.

36
Q

Pyroclastic Rocks

A

Rocks composed of consolidated rock fragments ejected during a volcanic eruption

37
Q

Tuff

A

A rock composed mainly of tiny, ash-size fragments cemented together

38
Q

Welded Tuff

A

A pyroclastic deposit composed of particles fused together by the combination of heat still contained in the deposit after it has come to rest and the weight of overlying material

39
Q

List the two criteria by which igneous rocks are classified.

A

Texture and composition

40
Q

How are granite and rhyolite different? In what way are they similar?

A

Granite is phaneritic

Rhyolite is aphanitic

41
Q

Describe each of the following in terms of composition and texture: diorite, rhyolite, and basalt porphyry.

A

Diorite: intermediate, phaneritic
Rhyolite: felsic, aphanitic
Basalt porphyry: mafic, porphorytic

42
Q

Geothermal Gradient

A

The gradual increase in temperature with depth in the crust. The average is 30 degrees Celsius per km in the upper crust

43
Q

Decompression Melting

A

Melting that occurs as rock ascends due to a drop in confining pressure

44
Q

What role does water play in the formation of magma?

A

Water lowers the melting temperature of the rock

45
Q

What is one way that basaltic magma can generate felsic magma?

A

Subduction zone, when mantle melts next to continental crust, there is new magma

46
Q

Crystal Settling

A

A process that occurs during the crystallization of magma, in which the earlier-formed minerals are denser than the liquid portion and settle to the bottom of the magma chamber

47
Q

Magmatic Differentiation

A

The process of generating more than one rock type from a single magma

48
Q

Assimilation

A

In igneous activity, the process of incorporating country rock into a magma body

49
Q

Magma Mixing

A

The process of altering the composition of a magma through the mixing of material from another magma body

50
Q

How does the crystallization and settling of the earlier formed minerals affect the composition of the remaining magma?

A

Earliest formed crystals are mafic, they settle and what is left behind is more felsic (more silica rich)

51
Q

Partial Melting

A

The process by which most igneous rocks melt. Since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results

52
Q

What is the process thought to generate most basaltic magmas?

A

Partial melting of the earth’s mantle

53
Q

What is the process thought to generate most granitic magmas?

A

Transfer of heat from rising magma that is too dense to overtake the continental crust

54
Q

Host Rock/Country Rock

A

Preexisting crustal rocks intruded by magma. Host rock may be displaced or assimilated by magmas

55
Q

Intrusions/Plutons

A

A structure that results from the emplacement and crystallization of magma beneath the surface of Earth

56
Q

Tabular

A

Describing a feature such as an igneous pluton that has tow dimensions that are much longer than the third

57
Q

Massive

A

An igneous pluton that is not tabular in shape

58
Q

Discordant

A

A term used to describe plutons that cut across existing rock structures, such as bedding planes

59
Q

Concordant

A

A term used to describe intrusive igneous masses that form parallel to the bedding of the surrounding rock

60
Q

Dikes

A

A tabular-shaped intrusive igneous feature that cuts through the surrounding rock

61
Q

Sill

A

A tabular igneous body that was intruded parallel to the layering of preexisting rock

62
Q

Columnar Jointing

A

A pattern of cracks the forms during cooling of molten rock to generate columns

63
Q

Batholith

A

A large mass of igneous rock that formed when magma was emplaced at depth, crystallized and subsequently exposed by erosion

64
Q

Stock

A

A pluton similar to but smaller than a batholith

65
Q

Laccolith

A

A massive igneous body intruded between preexisting strata

66
Q

Distinguish among batholiths, stocks, and laccoliths in terms of size and shape.

A

Batholiths-big
Stocks-smaller than batholiths
Laccoliths-mushroom shape

67
Q

Describe dikes and sills using: massive, discordant, tabular, and concordant.

A

Dikes and sills are tabular
Dikes are discordant
Sills are concordant

GEO 101 (19 decks)

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