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GEOLOGY > Igneous Rock Classification > Flashcards

Igneous Rock Classification Flashcards

2.5-2.10

1
Q

Three main igneous textures

A

crystalline
fragmental
glassy

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2
Q

define aphanitic

A

fine grained crystals grow quickly under conditions of rapid cooling, typically in extrusive settings

1 stage of cooling

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3
Q

define phaneritic

A

coarse grained crystals grow larger by cooling slowly typically intrusive

1 stage of cooling

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4
Q

defined porphyritic

A

both small and large crystals (called phenocrysts)

initial slow cooling followed by rapid cooling (usually after eruption)

2 stages of cooling

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5
Q

texture of rhyolite andesite and basalt

A

aphanitic

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6
Q

texture of granite diorite and gabbro

A

phaneritic

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7
Q

mafic melts have a high proportion of

A

magnesium and iron relative to silica

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8
Q

mafic rocks are usually ___ colored

A

dark

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9
Q

mafic rocks have ____ specific gravity than felsic

A

higher

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10
Q

Basalt and diorite M/F

A
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11
Q

Felsic color

A

lighter

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12
Q

felsic specific gravity

A

lower than mafic

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13
Q

rhyolit and granite M/F

A

felsic

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14
Q

Grain size has to do with

A

history not composition

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15
Q

peridotite M/F A/P I/S/M

A

ultramafic phaneritic igneous

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16
Q

andesite M/F A/P I/S/M

A

intermediate anphanitic igneous

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17
Q

komatite / picrite M/F A/P I/S/M

A

ultramafic anphanitic igneous

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18
Q

granite M/F A/P I/S/M

A

felsic phaneritic igneous

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19
Q

freezing temp is proportional to __ density __ silica content ____how mafic it is

A

+ - +

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20
Q

what is pumice

A

felsic rock full of vesicles
it floats

glassy igneous rock

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21
Q

what is scoria

A

vesicular and glassy mafic rock

glassy igneous

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22
Q

what is obsidian

A

glassy felsic rock, no vesicles

glassy igneous

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23
Q

what the 3 main glassy igneous rocks

A

pumice
scoria
obsidian

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24
Q

what are the pyroclastic igneous rocks

A

tuff: fused volcanic ash
volcanic breccia : angular fragments that have fused together

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25
Q

a volcano is

A

a mountain constructed by the eruption of molten rock from earths interior

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26
Q

volcanoes are a direct consequence of

A

plate tectonics and mantle convections

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27
Q

Products of volcanic eruptions

A

lava flows
volcanic gases
pyroclastic debris

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28
Q

lava flows are

A

molten rock that moves over the ground

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29
Q

volcanic gases are

A

expelled vapor’s and aerosols

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30
Q

pyroclastic debris are

A

fragments blown out of a volcano

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31
Q

in violent eruptions

A

gas escape is difficult

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32
Q

in mellow eruptions

A

gas escape is easy

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33
Q

mellow eruptions have _ viscosity

A

low

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34
Q

violent eruptions have _ viscotisy

A

high

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35
Q

basaltic lava has

A

low viscosity and can travel long distances

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36
Q

andesitic lava is

A

too viscous to flow far and tends to break up as it flows

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37
Q

felsic lava is

A

so viscous that it may pile up in a dome shaped mass

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38
Q

basaltic lava flows are

A

very hot, mafic, low viscosity

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39
Q

basalt flows are often

A

thin and fluid
go long distances

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40
Q

Lava tubes are

A

conduits for basaltic lava

41
Q

andesitic lava flows have

A

higher silica , a bit viscous, mound the vent and slow f lowly, cooled crust cracks into rubble

42
Q

rhyolitic lava flows

A

high silica (felsic), more viscous, don’t really flow at all, can be blown out during an eruption

43
Q

rhyolitic eruptions look like

A

big smoke clouds

44
Q

pyroclastic flows are

A

flow of hot molten pyroclastic debris,

500-1000C ash that travels at up to 300 Km/h

45
Q

Tuff is

A

lithified ash

46
Q

an air fall tuff accumulates like

A

snow

47
Q

an ignimbrite is a

A

tuff that is deposited while still hot; it welds together

48
Q

pyroclastic debris can trap

A

volcanic gas

49
Q

pyroclastic debris has ____ specific gravity

A

low

50
Q

3 types of volcanoes

A

shield volcanoes
cinder cones
stratovolcanoes

51
Q

magma chambers are located

A

in the upper crust

52
Q

fissures happen when

A

magma erupts along a linear tear
or through a pipe shaped conduit with a crater at the top

53
Q

a crater is

A

a bowl shaped depression atop a volcano

54
Q

a caldera is

A

a gigantic volcanic depression, they quickly fill with water and become a lake

55
Q

calderas are _____ than craters

A

much larger

56
Q

shield volcanoes are shaped like

A

a dome

57
Q

shield volcanoes have what kind of lava

A

low viscosity basaltic

58
Q

shield volcanoes have ___ violent eruptions

A

not very

59
Q

what kind of volcano is hawaii

A

shield volcano

60
Q

cinder cones are what shape

A

a cone dumbfuck no shit

61
Q

cinder cones are the smallest type of

A

volcano

62
Q

cinder cones form from

A

ejected fragments that have built up at the angle of repose around the vent

63
Q

stratovolcanoes are also known as

A

composite volcanoes

64
Q

stravolcano shape

A

large cone shape, steep slopes

65
Q

stratovolcanoes are made of

A

alternating layers of felsic lava tephra and debris

66
Q

mt st helen’s, mt fuji, mt vesuvius and mt pinotubo are all what kind of volcano

A

stratovolcano

67
Q

stratovolcanoes have a ____ violent eruption

A

VERY

68
Q

rank the following in size, caldera,
cinder volcanoes, shield volcanoes, stratovolcano small to large

A

cinder
strato
caldera
shield

69
Q

3 main Eruption styles

A

effusive
explosive
plinian

70
Q

effusive characteristics

A

outpouring of basaltic lava
rivers of lava
lava lakes can form near the vent
lava fountains 500 m high

71
Q

explosive characteristics

A

high gas pressure
more viscous siO2 rich
mostly andesitic and rhyolitic

72
Q

Plinian characteristics

A

often destroy a part of the stratovolcano that created them

create a convective cloud

73
Q

why are they called plinean

A

roman scholar pliny saw vesuvius erupt

74
Q

what is a lahar

A

volcanic ash and debris mixed with water which travel along drainage ways

75
Q

when do lahars occur

A

snow ice or rain
eruption or not

76
Q

volcanoes cause landslides as

A

movement destabilizes flanks

debris falls off the mountain

77
Q

volcanoes cause tsunamis by

A

destabilizing flanks or caldera collapse

78
Q

active volcanoes

A

are erupting, have erupted recently, are likely to erupt

79
Q

dormant volcanoes

A

haven’t erupted in hundreds to thousands of years

80
Q

extinct volcanoes

A

are no longer capable of erupting

81
Q

to predict eruptions

A

magma movement causes a change in shape that can be measured with tiltmeters or satellite radar

82
Q

to mitigate volcanic hazards

A

don’t build near them
don’t build on lahar drainage routes

83
Q

pinatubo is what eruption type

A

plinian

84
Q

mount kilauea is what type of volcano

A

shield volcano

85
Q

mount kilauea has what eruption type

A

hawaiian (i know its stupid)

86
Q

Eyjafjallajokull has what type of eruption

A

strombolian (i know what the fuck)

87
Q

white island eruption type

A

phreatic

88
Q

vesuvius eruption type

A

plinian or vesuvian

89
Q

nyiragongo volcano type

A

stratovolcano

90
Q

hawaiian characteristics

A

predominately effusive, flows with minor scoria

91
Q

strombolian characteristics

A

periodically erupts a fountain of scoria lapilli and ash

92
Q

vulcanian characteristics

A

erupts both scoria tapili and tall plumes of pyroclastic debris

93
Q

phreatic characteristics

A

groundwater interacts with magma producing a steam explosion and blocks of wall rock

94
Q

phreatomagmatic characteristics

A

eruption involves steam explosion but also eruption of wet ash, lapilli, and blocks of lava

95
Q

surtseyan characteristics

A

seawater enters the magma chamber and does phreatomagmatic making steam explosions

96
Q

nyiraragongo is on lake

A

kivu

97
Q

nyirgongo is characterized by its

A

vents and fissures

98
Q

limnic eruptions are

A

eruptions of gases in a lake, slow release of poison

99
Q

lake nyos eruption type

A

limnic

GEOLOGY (12 decks)

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