Brainscape's Knowledge GenomeTM

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


See full index

Geology > Mama and igenous rocks > Flashcards

Mama and igenous rocks Flashcards

1
Q

What is a volcano?

A

vent where molten rock comes out of Earth

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

how are igneous rocks formed?

A

by cooling from a melt. they start to crystallize at high temps

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

what is the difference between magma and lava?

A

magma = molten rock below ground
lava = molten rock above surface

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

what is the difference between intrusive and extrusive rocks?

A

extrusive: quickly cools at the surface
Intrusive: cool underground and much slower

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

name three elements that are part of the extrusive igneous rock formation

A

lava flows (streams or mounds of cooled melt)
pyroclastic flow and fall (fragmented magma)
volcanic ash (fine particles of volcanic glass)

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

where does magma form?

A

not everywhere. only in special tectonic conditions. partial melting occur in crust and upper mantle

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

what is melting of magma caused by?

A

pressure release, volatile addition, heat transfer

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

what is decompression?

A

magma ascent that leads to pressure release. at base of crust, T is hot enough to melt rock but due to high P, it doesn’t. if P is decreased (shallower), rock can melt and become magma

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

what is addition of volatiles?

A

flux melting. volatiles lower melting T of hot rock. H2O and CO2. subduction carries hydrous minerals into mantle and they break down to release H2O which causes partial melting of overlying mantle.

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

what is heat transfer melting?

A

rising magma carries mantle heat with it. raises T in nearby crustal rock which then melts.

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

what are the 3 components of magma?

A

solid: solidified mineral crystals
liquid: ions in the melt itself
gas: dissolved gas in magma

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

why is dry and wet magna>

A

dry: scarce variables
wet: up to 15% volatiles

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

what are the 4 major types of magma?

A

felsic, intermediate, mafic, ultramafic (decreasing silica_

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

what kinds of magma come from the mantle vs the crust?

A

mantle: ultra-mafic and mafic
crust: mafic, intermediate, felsic

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

why does partial melting occur?

A

rocks rarely melt uniformly, only a portion of the rock melts. it yields a silica rich magma

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

does si-poor or si-rich melt first?

A

si-rich minerals melt first

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

what is assimilation?

A

the process whereby solid or fluid foreign material is incorporated into magma

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

what is a xenolith?

A

a piece of rock trapped in another type of rock. rock embedded in magma while the magma was cooling

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

what is a pluton?

A

a large igneous rock body that forms when magma cools and solidifies underground

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

how does magma move?

A

it is buoyant, tends to rise upward. can move upward in the crust and may breach the surface VOLCANO. transfers mass from deep to shallow parts of Earth

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

why does magma rise?

A

less dense than surrounding rocks. more buoyant thus lifted upward. weight of overlying rock creates pressure and it squeezes magma upward

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

what is lower viscosity generated by?

A

low silica
higher T
higher volatile content
More silica means more tetrahedra and they get linked up and become more viscous

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

how fast does magma cool?

A

depends on depth. deep magma takes longer to cool than shallow magma. spherical bodies cool slowly, tabular faster.

24
Q

what is fractional crystallization?

A

removal of early formed crystals from an originally homogeneous magma (for example, by gravity settling) so that these crystals are prevented from further reaction with the residual mel

25
what does bowen's reaction series state?
low temp, more felsic = last to crystallize high temp, ultramafic = first silicate minerals to crystallize
26
what are the crystal sizes based on cooling rate?
intrusive = lose heat slowly = large crystals extrusive = cool rapidly = no time to grow big crystals
27
name if felsic or mafic: basalt, olivine, quartz, feldspar
mafic, ultra-mafic, most felsic, felsic
28
what are two types of extrusive volcano eruption?
lava effusion: low viscosity lava flows and spreads outwards explosive eruptions: high viscosity (felsic) magma erupts explosively
29
how does magma invade preexisting wall rock?
fracturing and partial melting of host tock. forcing open cracks. high heat (baked zone, chill margin)
30
what is stoping
process by which local rock is broken up and removed by the upward movement of magma.
31
smaller intrusions tend to form shallowly, larger = deeper
32
what are tabular intrusions?
uniform thickness can be traced laterally *sill: parallel to rock layering dike: cut across rock layering*
33
how do dikes intrude?
cut across preexisting layers. spread rocks sideways
34
how do sills intrude?
injected parallel to preexisting layering. intruded close to surface. cause uplift
35
igneous intrusion -> pluton -> batholith
batholiths form above subduction zones and mark former subduction
36
what do magma chambers do?
feed overlying volacnoes can cool to become plutons
37
how is a pluton exposed?
continued uplift and erosion. intrusive rocks are more resistant to erosion so they stand high on the landscape.
38
what is unroofing?
erosion of covering geological units. what exposes a pluton
39
what are the different arranements of minerals in igneous rocks?
crystalline: crystals fit like jigsaw puzzle fragmental: pieces of shattered preexisting rocks vitric/glassy: solid glass or glass shards
40
what are the two types of igneous textures and their characteristics?
fine grained: rapid cooling, extrusive, no time to grow coarse-grained: slow cooling, intrusive
41
what is porphyritic texture?
mixture of coarse and fine crystals. two-stage cooling history. slow cooling (large phenocrysts) eruption cools remaining magma rapidly
42
how are glassy textures formed?
extremely rapid cooling of lava. solid mass of glass or crystals surrounded by glass
43
name felsic vesicular rocks
pumice and scoria obisidian is felsic but not vesicular
44
name pyroclastic rocks. what are they?
fragments of violent eruptions tuff - from volcanic ash breccia - larger volcanic fragments cemented together
45
what is partial melting?
rock is subjected to temperatures high enough to cause certain minerals to melt, but not all of them
46
partial melting and fractional crystallization
they are inverse processes. felsic minerals crystallize last and thus melt first. thus, felsic magma has lower temp than mafic magma
47
where does igneous activity occur? 4
isolated hot spots volcanic arcs bordering trenches MORs continental rifts
48
describe mid-ocean ridges
rifting spreads plates leading to decompression melting basaltic magma wells up and created magma chambers solidifies as gabro moves upward to form dikes or extrude MAFIC MAFIC
49
what is decompression melting?
When rock rises up in order to melt because deeper in there is too much pressure. Decompression allows it to lower pressure in order to melt and turn into magma
50
where are volcanic arcs formed?
When oceanic plates collide, subduction occurs, where one plate slides beneath the other. Typically, the older, denser, colder plate will subduct, and the younger, warmer, more buoyant plate will override it. It is at these subduction boundaries where volcanic island arcs form.
51
why are volcanic arcs formed?
subduction adds volatiles (water) rocks of asthenosphere partially melt magma rises and creates volcanoes on overriding plate
52
continental rifts
places where cont. lithosphere is being stretched. rifting thins the lithosphere. causes decompressional melting of mafic rock and heat transfer melts crust creating felsic magmas east african rift valley!
53
what are hot spots
independent of tectonic plate boundaries. erupt through oceanic (mafic) or cont. (mafic and felsic) crust. burn volcano chain through overriding tectonic plate. creates track HAWAII
54
large igneous provinces
extremely large accumulation of igneous rocks, including intrusive and extrusive, arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics.
55
LLLM
low silica low viscosity liquidy mafic

Geology (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions