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GEOS 3464 EARTH MATS > EXAM FINAL MATERIAL > Flashcards

EXAM FINAL MATERIAL Flashcards

1
Q

CHAPTER 10

A
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2
Q

describe hypabyssal rocks and what they are.

A
  • form near the surface
  • cool relatively quickly
  • fine grained
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3
Q

describe plutonic rocks and what they are.

A
  • form at depth
  • cool slowly
  • coarse grained/visible crystals
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4
Q

why do magmas form?

A

they form when rock is melted

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5
Q

why do magmas ascend upwards?

A

they are less dense than the surrounding country rock

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6
Q

how is modal rock analysis used?

A

chemical composition is derived from modal analysis and used for the IUGS classification of igneous rocks

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7
Q

what is mineralological classification?

A

classifying rocks based on they mineralogical composition

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8
Q

what is chemical composition?

A

classifying rocks based on their chemical composition

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9
Q

describe the difficulty of obtaining modal analysis from the different rock types

A
  • coarse-grained plutonic is easy
  • fine-grained volcanic is difficult
  • glassy rocks is impossible
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10
Q

how are igneous rocks classified?

A
  1. mode of occurrence
  2. mineralogical makeup
  3. chemical composition
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11
Q

what is the problem with historic classification?

A

contains a huge number of rock names, not used consistently

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12
Q

what method is used to classify very fine-grained/glassy rocks?

A

chemical analysis

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13
Q

what is latent heat of fusion?

A

the amount of energy that must be applied to a rock to melt it.

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14
Q

what role does latent heat of fusion play in melting?

A

prevents large scale melting in the earth

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15
Q

what are discordant intrusive magma bodies?

A

if the intrusive body cuts through the surrounding rock, it is discordant

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16
Q

what are Cordant intrusive magma bodies

A

if the intrusive body parallels the surrounding rock, it is Concordant

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17
Q

in what direction do magmas always intrude?

A

the minimum stress direction

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18
Q
A
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19
Q

what are dikes?

A

a vertical intrusive igenous body

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20
Q

what are sills?

A

a horizontal intrusive igneous body

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21
Q

how are dikes accommodated in the crust

A
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22
Q

how are sills accommodated in the crust?

A
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23
Q

what types of igneous intrusions are associated with crustal extension?

A

dikes and flood basalts

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24
Q

what types of igneous intrusions are associated with crustal compression?

A
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25
Q

are intrusive dikes common at any of the plate boundaries?

A
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26
Q

what are chilled margins?

A
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27
Q

how do chilled margins form?

A
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28
Q

what are cone sheets?

A

when pressure increases fractures propagate from the top of the magma chamber to the surface magma seeps in, creating cone sheets

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29
Q

what are ring dikes

A

when pressure decreases, the roof sinks into the chamber, magma wells up into the fracture

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30
Q

how are ring dikes/cone sheets associated with calderas?

A

ring fractures penetrate through to earths surface

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31
Q

what are diatremes?

A

elongate bodies filled with broken breccia fragments.

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32
Q

how do diatremes form?

A
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33
Q

what characteristics are diatremes associated with?

A
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34
Q

do diatremes have any particular mineral components?

A

YES
- diamond bearing rock
- mg rich mica phlogopite (RARE)

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35
Q

how do diatremes relate to a maars?

A

maars are the surface expression of diatremes

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36
Q

what are lopoliths?

A

large, saucer-shaped intrusions having
diameters of up to hundreds of kilometers

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37
Q

at what scale do lopoliths occur at?

A

massive scale (hundreds of kms)

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38
Q

what is the largest known lopolith and its dimensions?

A

the bushveld complex
- diameter of 300 km
- thickness of 8km

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39
Q

how was the Sudbury Ontario lopolith triggered?

A

a large meteorite impact

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40
Q

what processes are important in large scale magmatic intrusions that may form ore bodies?

A
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41
Q

what are batholiths?

A

large scale bodies of granitic rock that have large exposures on the surface of the earth

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42
Q

What is the composition of a flood basalt

A
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43
Q

what is the composition of a batholith?

A

ALWAYS granite

44
Q

how do batholiths form?

A
45
Q

are there any important batholiths in north America?

A

yes, Yosemite is made of mostly batholiths

46
Q

What controls the shape of lava bodies once they reach the surface?

A

the body is controlled by viscosity

47
Q

what are pyroclastic materials?

A

clastic rocks composed of rock fragments ejected by explosive volcanism

48
Q

how are pyroclastic materials classified?

A
49
Q

What factors are important in the development of pyroclastic materials?

A
50
Q

Volcanic Explosivity Index, range, what is it describing, what factors are important in classification?

A
51
Q

what is volcanic explosivity based on?

A
  • the volume of tephra produced
  • height of the eruption column
52
Q

Why do we know so much about the eruption of mt vesuvius?

A

pliny the younger eye witness accounts

53
Q

when was the eruption of mt Vesuvius?

A

79 AD

54
Q

what are flood basalts?

A

eruptions of basaltic lava pouring from long fissures

55
Q

how do flood basalts form?

A

large mentle plume upwells, associated with the breakup of tectonic plates

56
Q

what volcanic processes are flood basalts associated with?

A

breakup of tectonic plates (divergent boundaries)

57
Q

are shield volcanoes associated with flood basalt processes?

A
58
Q

are flood basalts associated with mass extinction events?

A

YES

59
Q
A
60
Q

do composite volcanoes typically produce lava flows?

A

yes

61
Q

what are the decan traps?

A

large flood basalt province in indai

62
Q

what are the Siberian traps?

A
63
Q

what are columnar joints?

A

sections of flood basalts that propagate into the flow from upper and lower bounds

64
Q

how are volcanoes classified?

A
  • shape of volcanic structures they form
65
Q

what is the VEI

A

volcanic explosivity index

66
Q

what does the VEI tell us?

A

quantifies the explosive power of volcanic eruptions

67
Q

how does viscosity relate to eruption magnitude?

A
  1. High viscosity:
    - slower moving lava
    - more gas bubbles
    - more explosive
68
Q

what is tephra?

A

fragmental pyroclastic material expunged by volcanic explosion

69
Q

what are the size denominations of pyroclastic materials and their names?

A

> 64 mm diameter= bombs
63-2mm diameter= lapilli
2mm or less=ash

70
Q

how do spatter cones develop?

A

blobs accumulating around volcanic events

71
Q

how is volcanic structure shape determined?

A
  1. Whether eruptions come from central vents or long fissures
  2. Explosivity
72
Q

what makes composite volcanoes composite?

A

they alternate between pyroclastic and lava eruption, forming stratified deposits

73
Q

what is the transport mechanism of pyroclastic debris

A

debris combines with water to form volcanic mud flows called lahars

V HAZARDOUS

74
Q

how do composite volcanoes differ from other volcanoes?

A

they produce lava AND pyroclastic material

75
Q

what processes are related to caldera forming events?

A
76
Q

what are calderas?

A

volcanoes that collapse when the magma chamber empties

77
Q

what lava compositions are typical in calderas?

A
78
Q

any notable calderas in north america?

A
79
Q

where do caldera eruptions fall on the VEI?

A
80
Q

be aware of recent volcanic activity in yellowstone

A
81
Q

what is resurgent doming?

A
82
Q

is resurgent doming seen in yellowstone?

A
83
Q

is resurgent doming seen in valle caldera in los alamos?

A
84
Q

describe pyroclastic air fall processes

A
85
Q

describe pyroclastic flow processes

A
86
Q

describe phroclastic debris

A
87
Q

describe epiclastic processes

A
88
Q

what are the two types of ash transport from a caldera?

A
  • air fall
  • flow
89
Q

what is air fall ash?

A

ash ejected high into atmosphere, cools by the time it reaches the surface

90
Q

what is flow ash?

A

hot, dense particles moving laterally quickly

91
Q

what is important to remember about flow ash?

A

it is moving so quickly there is little time to cool

92
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93
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96
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97
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98
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99
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100
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101
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102
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103
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104
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105
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106
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107
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GEOS 3464 EARTH MATS (3 decks)

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