CHPTR 3/4 Igneous Rocks Flashcards

1
Q

magma

A

molten rock beneath the surface of the Earth

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2
Q

parts of magma

A

molten rock, crystals, dissolved water, gas

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3
Q

what negative ion is lava made of

A

SiO4^4- (silicate ion)

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4
Q

lava

A

magma once it reaches the surface

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5
Q

plutonic

A

intrusive - cools slowly underground - larger crystals

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6
Q

volcanic

A

extrusive - cools quickly at the surface - smaller crystal grains

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7
Q

felsic lava

A

high silica, lower melting point, high viscosity

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8
Q

mafic lava

A

low silica, higher melting point, low viscosity

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9
Q

interlocking grains

A

similar to a camo pattern - evidence that the rock crystallized from liquid state

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10
Q

pyroclastic texture

A

rock formed from particles that travelled from volcano through the air. when they land on the ground they weld together

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11
Q

glassy

A

cooling is so fast that there is no time for crystals to form

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12
Q

vesicular

A

voids formed by bubbles of volatiles that expanded close to the surface and could not escape from the lava/magma

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13
Q

amygdaloidal

A

vesicles that have been filled in with secondary minerals long after the flow cooled

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14
Q

frothy

A

vesicular rock and very light - more air than rock

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15
Q

phaneritic texture

A

slow cooling, crystals visible - like camo pattern

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16
Q

porphyritc

A

mixed rate of cooling. starts cooling then phenocrysts form. cooling is then faster and remaining melt forms groundmass - big rock in small rock

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17
Q

groundmass

A

the small crystals in porphyritic rocks

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18
Q

phenocrysts

A

large crystals within a porphyritic rock

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19
Q

aphanitic

A

fast cooling produces fine grained rock and crystals not visible - “looks like a rock”

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20
Q

pegmatitic

A

large grains formed in water rich magma. crystals larger than 1cm

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21
Q

felsic rock intrusive and extrusive rock pairs

A

intrusive: granite - extrusive: rhyolite

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22
Q

intermediate rock intrusive and extrusive rock pairs

A

intrusive: diorite - extrusive: andesite

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23
Q

mafic rock intrusive and extrusive rock pairs

A

intrusive: gabbro - extrusive: basalt

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24
Q

ultramafic rock intrusive and extrusive rock pairs

A

intrusive: peridotite - extrusive: komatiite

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25
Q

tabular

A

flat body

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26
Q

massif

A

not flat - shapeless

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27
Q

concordant

A

parallel to sedimentary layers

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28
Q

discordant

A

cut across existing rock layers

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29
Q

dykes

A

tabular, discordant pluton

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30
Q

sills

A

tabular, concordant plutons

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31
Q

laccoliths

A

dyke extends upwards and forms a little rock mound to bulge upwards

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32
Q

batholiths

A

massif, area >100km - evidence of past subduction zones

33
Q

stocks

A

smaller than batholiths igneous extrusion

34
Q

dike swarms

A

set of parallel dikes at the same age

35
Q

mantle plume

A

adds heat to an area - determines which volcanoes in Hawaii are active

36
Q

what happens to boiling point as you decrease temp

A

it also decreases

37
Q

how can lowering pressure melt rocks

A

at a mid ocean ridge, the plates seperate
this causes the mantle to flow upwards into the low pressure area

38
Q

in ocean volcanoes, is the lava felsic or mafic

A

mafic

39
Q

how can changing composition melt rocks

A

ocean crust subducts, bringing water into the mantle of the continental plate, this lowers the melting point and ultramafic melt forms

40
Q

volcanic ash

A

pyroclastic material <2mm

41
Q

lapilli

A

pyroclastic material 2-64mm

42
Q

bombs/blocks

A

pyroclastic material >64mm

43
Q

pyroclastic flow

A

a fast-moving, high-density current of hot volcanic rocks and gas that flows down the side of a volcano

44
Q

lahar

A

volcanic mud flow or debris - can occur without an eruption

45
Q

Volcano Explosivity Index

A

used to measure the size of an eruption

  • measured by the volume of material ejected and the height of eruption column
46
Q

shield volcano

A

formed by mafic lava. caldera forms as the summit collapses. very wide and gentle slopes

47
Q

caldera

A

lake at top of volcano caused by its summit collapsing into itself

48
Q

cinder/scoria cone

A

formed by one eruptive eps. monogenetic

49
Q

monogenetic

A

a volcano that only erupts once in its life

50
Q

strato-volcano/composite volcano

A

alternating layers of ash and lave, steeper slopes - generally andesite - rhyolite

51
Q

approximate angle of a composite volcanoe

A

45 degrees

52
Q

volcanic dome

A

A lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano

after the initial explosion which results in a crater

53
Q

what does a symmetrical volcano imply

A

it is young and active

54
Q

what kind of lava is in fissure eruptions

A

mafic (low viscosity) - basaltic lava flow

55
Q

volcanic pipes

A

the hard part of the the conduit after the on of the volcano is weathered away

56
Q

what kind of tectonic boundary has the least number of volcanoes

A

transform

57
Q

what kind of heat transfer does the lithosphere experience

A

conduction

58
Q

what kind of heat transfer does the mantle experience

A

convection

59
Q

what kind of heat transfer does the outer core experience

A

convection

60
Q

what kind of heat transfer does the inner core experience

A

conduction

61
Q

volcanic assimilation

A

rocks surrounding magma chamber (host rocks) break off and mix with magma

62
Q

magma mixing

A

two chambers of magma connect and mix

63
Q

magmatic differentiation

A

crystallization and settling
- different temp. causes crystals to form
- crystals sink to the bottom
- remaining liquid is more felsic

64
Q

Bowen’s reaction series definition and order of series. + why is Plagioclase feldspar unique

A

order of crystallization with a change in temperature

Highest temp/Crystallizes first
- olivine
- pyroxene
- amphibole
- biotite
- potassium feldspar, muscovite, quartz
Lowest temp/Crystallizes last

Plagioclase has continuous series of crystallizations

65
Q

pluton

A

a large body of igneous rock that forms when magma solidifies underground

66
Q

why is felsic lava explosive and mafic is not

A

in mafic lava, gas can escape
in felsic lava, the gas cannot escape

67
Q

pahoehoe

A

higher temperature mafic lava (1100-1200 C)

68
Q

aa

A

lower temperature mafic lava (1000-1100 C)

69
Q

underwater mafic lava

A

pillow lava

70
Q

what is dominant gas extruded during volcanic eruption + what percentage

A

8% water vapour

71
Q

Volcano emissions of carbon dioxide ____ times less than the human contribution

A

100

72
Q

Most recent super volcano

A

Toba on Sumatra in Indonesia
74 000 years ago

73
Q

What is most likely next supervolcano

A

Yellowstone

74
Q

what kind of plate boundary forms the most volcanoes

A

convergent plate boundaries - specifically subduction zones

75
Q

What formed the Andes

A

Ocean - continent subduction zone

76
Q

What formed the Appalachians

A

continent- continent convergent boundary

77
Q

what formed the Himilayas

A

continent-continent convergent boundary

78
Q

What formed the Alps

A

continent-continent convergent boundary