Brainscape's Knowledge GenomeTM

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


See full index

GEOS 3464 EARTH MATS > EXAM 3 MATERIAL > Flashcards

EXAM 3 MATERIAL Flashcards

1
Q

describe hypabyssal rocks and what they are.

A
  • form near the surface
  • cool relatively quickly
  • fine grained
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe plutonic rocks and what they are.

A
  • form at depth
  • cool slowly
  • coarse grained/visible crystals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why do magmas form?

A

they form when rock is melted

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

why do magmas ascend upwards?

A

they are less dense than the surrounding country rock

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

how is modal rock analysis used?

A

used for the IUGS classification of igneous rocks

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

what is mineralological classification?

A

classifying rocks based on they mineralogical composition

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

what is the chemical composition classsification?

A

classifying rocks based on their chemical composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how are igneous rocks classified?

A
  1. mode of occurrence
  2. mineralogical makeup
  3. chemical composition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the problem with historic classification?

A

contains a huge number of rock names, not used consistently

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

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

A

chemical analysis

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

what is latent heat of fusion?

A

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

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

what role does latent heat of fusion play in melting?

A

prevents large scale melting in the earth

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

what are discordant intrusive magma bodies?

A

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

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

what are Cordant intrusive magma bodies

A

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

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

in what direction do magmas always intrude?

A

the minimum stress direction

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

what are dikes?

A

a vertical intrusive igenous body

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

what are sills?

A

a horizontal intrusive igneous body

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

what types of igneous intrusions are associated with crustal extension?

A

dikes and flood basalts

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

what types of igneous intrusions are associated with crustal compression?

A

plutons, sills

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

are intrusive dikes common at any of the plate boundaries?

A

YES

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

what are chilled margins?

A

edges of an igneous intrusion where magma cool rapidly due to contact with colder surrounding rock

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

how do chilled margins form?

A

magma cools rapidly due to contact with colder surrounding rock

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

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

what are ring dikes

A

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

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

how are ring dikes/cone sheets associated with calderas?

A

ring fractures penetrate through to earths surface

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

what are diatremes?

A

elongate bodies filled with broken breccia fragments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

how do diatremes form?

A

magma rises quickly, surrounding rock fragments into magma plume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what characteristics are diatremes associated with?

A

explosive volcanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

do diatremes have any particular mineral components?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

how do diatremes relate to a maars?

A

maars are the surface expression of diatremes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what are lopoliths?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

at what scale do lopoliths occur at?

A

massive scale (hundreds of kms)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is the largest known lopolith and its dimensions?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

how was the Sudbury Ontario lopolith triggered?

A

a large meteorite impact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what are batholiths?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the composition of a flood basalt

A

basaltic lava

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what is the composition of a batholith?

A

ALWAYS granite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

how do batholiths form?

A

magma intrusion and subsequent cooling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

are there any important batholiths in north America?

A

yes, Yosemite is made of mostly batholiths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

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

A

the body is controlled by viscosity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what are pyroclastic materials?

A

clastic rocks composed of rock fragments ejected by explosive volcanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

how are pyroclastic materials classified?

A

-size
-composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

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

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what is volcanic explosivity based on?

A
  • the volume of tephra produced
  • height of the eruption column
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

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

A

pliny the younger eye witness accounts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

when was the eruption of mt Vesuvius?

A

79 AD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what are flood basalts?

A

eruptions of basaltic lava pouring from long fissures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

how do flood basalts form?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what tectonic processes are flood basalts associated with?

A

breakup of tectonic plates (divergent boundaries)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

are shield volcanoes associated with flood basalt processes?

A

YES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

are flood basalts associated with mass extinction events?

A

YES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

do composite volcanoes typically produce lava flows?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

what are the decan traps?

A

large flood basalt province in indai

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

what are the Siberian traps?

A

large flood basalt province in siberia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

what are columnar joints?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

how are volcanoes classified?

A
  • shape of volcanic structures they form
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

what is the VEI

A

volcanic explosivity index

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what does the VEI tell us?

A

quantifies the explosive power of volcanic eruptions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

how does viscosity relate to eruption magnitude?

A
  1. High viscosity:
    - slower moving lava
    - more gas bubbles
    - more explosive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

what is tephra?

A

fragmental pyroclastic material expunged by volcanic explosion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

how do spatter cones develop?

A

blobs accumulating around volcanic events

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

how is volcanic structure shape determined?

A
  1. Whether eruptions come from central vents or long fissures
  2. Explosivity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

what makes composite volcanoes composite?

A

they alternate between pyroclastic and lava eruption, forming stratified deposits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

what is the transport mechanism of pyroclastic debris

A

debris combines with water to form volcanic mud flows called lahars

V HAZARDOUS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

how do composite volcanoes differ from other volcanoes?

A

they produce lava AND pyroclastic material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

what are calderas?

A

volcanoes that collapse when the magma chamber empties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

what lava compositions are typical in calderas?

A

rhyolitic (felsic) lava

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

any notable calderas in north America?

A

yes, Yellowstone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

what is resurgent doming?

A

domes that result from caldera eruptions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

is resurgent doming seen in Yellowstone?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

is resurgent doming seen in valle caldera in los alamos?

A

yes

74
Q

describe pyroclastic air fall processes

A

glowing clouds of hot ash flows

75
Q

describe epiclastic processes

A

physical weathering and erosion of preexisting rocks

76
Q

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

A
  • air fall
  • flow
77
Q

what is air fall ash?

A

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

78
Q

what is flow ash?

A

hot, dense particles moving laterally quickly

79
Q

what is important to remember about flow ash?

A

it is moving so quickly there is little time to cool

80
Q

what are welded tuffs?

A

material from pyroclastic flow is hot enough to weld back into a single rock

81
Q

what is the CIPW normative classification?

A

a method by which chemical analyses of rocks can be recast into common anhydrous minerals.

82
Q

who developed the CIPW normative classification?

A
  • Washington
  • Cross
  • Iddings
  • Pirsson
83
Q

Why do CIPW norms predict minerals that many not be present in the mode of a rock

A

because CIPW does not calculate hyrdous minerals

84
Q

what are Komatiites

A

ultramafic lava

85
Q

why are Komatiites important?

A
  • give insight into early earths deep mantle billions of years ago
  • economic importance because of the nickel, copper and platinum elemental occurrences.
86
Q

what are Komatiites composition?

A

Lherzolite BUT the texture is consistent with lava flows

87
Q

What is a TAS diagram useful for?

A

determining total alkali/silica content when volcanic rocks are too fine grained for modal analysis

88
Q

is the TAS diagram a useful way of classification?

A

YES

89
Q

how does the Irvine-Baragar Classification of Volcanic Rocks work?

A

uses genetically related rocks and divides them into three main series for classification

90
Q

is the Irvine-Baragar classification of volcanic rocks popular?

A

yes

91
Q

what are the three main series of the Irvine-baragar classification?

A
  • alkaline
  • subalkaline
  • peralkaline
92
Q

what are the characteristics of the Alkaline series?

A
  • high alkali content
  • silica content
93
Q

what are the groups the Alkaline series is subdivided into?

A
  • Alkali olivine basalt
  • nephelinitic-leucitic-anaclitic
94
Q

what are the groups the Subalkaline series is subdivided into?

A
  • Tholeiites
  • Calcalkaline
95
Q

what is the difference between Tholeiites
Calcalkaline

A
  • Tholeiites are more iron rich
  • calcalkaline are richer in aluminum
96
Q

what are Ophiolites?

A

slivers of oceanic crust have been thrust onto continental margins

97
Q

how do Ophiolites form?

A

result of obduction

98
Q

what are ophiolites associated with?

A

three rock types are associated with the MORs

99
Q

what is the economic importance of divergent margins?

A

ore deposit formation

100
Q

what is the ocean island life cycle (simple)

A
  1. active magma rises to create seamount
  2. magma chamber cools to form a pluton
  3. seamount weight makes seafloor sink
101
Q

what are large igneous provinces? (LIP)

A

large scale flood basalts and their associated features (feeder dikes)

102
Q

do LIPs have any particular characteristics?

A

large area occurrence

103
Q

what are Aulacogens?

A

a failed third arm in a triple junction

104
Q

where is most volcanism seen in rock factories

A

M.O.R

105
Q

where is the least volcanism seen in rock factories?

A

cratons

106
Q

why is the Sudbury lopolith important?

A

it resulted from an meteorite impact

107
Q

what conditions are most closely associated with glaucophane?

A
  • HIGH pressure
  • LOW temperature
108
Q

what are the metamorphic facies associated with glaucophane

A

blueschist facies

109
Q

what is univariance in a three phase diagram?

A

all three coexisting phases are in equilibrium with each other

110
Q

what is divariance in a three phase diagram?

A

two independent variables that can vary while maintaining equilibrium among three phases.

111
Q

what is invariance in a three phase diagram?

A

no independent variables can vary freely and are constrained by equilibrium

112
Q

what is metamorphism?

A

the sum of all changes that take place in a rock

113
Q

what is a protolith

A

the original rock before it was metamorphosed

114
Q

what are protoliths of the most common types of metamorphic rock

A

shale-slate-phyllite-schist-gneiss

115
Q

what is a prograde reaction

A

changes that occur while temperature and/or pressure is INCREASING

116
Q

what is a retrograde reaction

A

changes that occur while temperature and/or pressure is DECREASING

117
Q

do retrograde reactions always occur?
why or why not?

A

NO

118
Q

what is the distinction between diagenesis and metamorphism

A

diagenesis are changes that take place in LOW temperature.
(metamorphism in high temp.)

119
Q

is melting a part of metamorphic reactions?

A

YES

120
Q

what is contact metamorphism?

A

magma intrudes in thermal aureoles, heats and subsequently changes rocks.

121
Q

how quick are metamorphic reactions?

A

slow

122
Q

how do fluids play a role in metamorphic reactions?

A

yes

123
Q

what is the biggest contributor to driving metamorphic reactions

A

Gibbs free energy

124
Q

describe the principal stress orientations

A
  • can be in opposite directions
  • they can be all equal OR all different
125
Q

what are the three stress motions that can be applied?

A
  • compressive
  • tensional
  • shearing
126
Q

how do metamorphic foliations develop?

A

perpendicular to the maximum compressive stress

127
Q

what is Metasomatism?

A

fluids present can remove or add new elements, changing composition

128
Q

Are rocks efficient at diffusing heat?

A

NO

129
Q

what is thermal diffusivity?

A

the ability of a material to conduct thermal energy

130
Q

what is regional metamorphism?

A

minerals with platy shapes rotate into orientations normal to the direction of stress.

!! CREATES FOLIATION !!

131
Q

what tectonic setting is associated with regional metamorphism?

A

convergent margins

132
Q

How are deeply buried and metamorphosed rocks exposed at the surface

A

they are uplifted and exhumed

133
Q

does crust thickening play a role in regional metamorphism?

A

YES

134
Q

what controls reaction rates in short range metamorphism?

A

diffusion

135
Q

what controls reaction rates in long order metamorphism?

A

fluid transport (Darcy’s law!)

136
Q

do subducted fluids play a role in regional metamorphism?

A

YES

137
Q

how is it possible to identify a protolith based on a metamorphic rock?

A

bulk chemical composition

138
Q

what is the most important thing in defining metamorphic grade?

A

mineral assemblages

139
Q

what is the difference between shale and schist?

A

SHALE contains 5% water

140
Q

what happens to water content during metamorphism?

A

water is liberated

141
Q

what is metamorphic grade?

A

expresses the intrensity of metamorphism

(inc grade=inc temp

142
Q

what must happen to Gibbs free energy for equilibrium to occur?

A

GFE is zero

143
Q

what direction does a metamorphic reaction move to?

A

reaction moves only in the direction that lowers GFE

144
Q

what are isograds?

A

the boundaries between index mineral zones

145
Q

how important is temp v. pressure during metamorphism

A

VERY

146
Q

what are index minerals?

A

minerals that represent specific equilibrium conditions

147
Q

what are components?

A

the minimum number of constituents needed to describe the phases present

148
Q

what are phases?

A

individual minerals, liquids and gases

149
Q

what are degrees of freedom?

A

how many variables can be changed without changing the phases present.

150
Q

what do iso-grads represent in regional metamorphism?

A

LOOSLEY represent metamorphic intensity

151
Q

how does recrystallization effect Gibbs-Free-Energy?

A

recrystallization results in a coarser mineral grain, decreasing the free energy

152
Q

what are the three groups of facies defined by Eskola?

A
  1. LOW P. HIGH T
  2. INC P. INC T (regional orogenic belts)
  3. HIGH P. LOW T
153
Q

who developed the concept of metamorphic facies and first recognized 3 groups of facies?

A

Pentti Elias Eskola

154
Q

what are geothermometers and what are they used for?

A

small number of metamorphic reactions very sensitive to changes in temperature.

!! composition is used to determine metamorphic temperature !!

155
Q

what are geobarometers?

A

small number of metamorphic reactions very sensitive to changes in pressure.

!! composition is used to determine metamorphic pressure !!

156
Q

how are metamorphic facies determined?

A

by studying the ENTIRE mineral assemblage, not a single index mineral.

157
Q

what is boudinage?

A

series of resisted deformation (string like sausages)

158
Q

what is pressure solution?

A

fluids formed due to melting of minerals at grain-to-grain contacts

159
Q

what are porphroblasts?

A

large mineral crystals in metamorphic rock grown within finer grained ground mass.

160
Q

what is porphoblastic texture?

A

large single crystals in a fine grained matrix

161
Q

what is porphoclastic texture?

A

rocks containing large relict minerals

162
Q

what is brittle/ductile transition in the crust?

A

the transition from upper, brittle crust to lower, ductile crust

163
Q

where does the brittle-ductile transition happen?

A

10-15 km

164
Q

what are pelites/pelitic rocks?

A

rocks containing an abundance of clay minerals

165
Q

what are petrogenetic grids?

A

lines that set limits on pressure and temperature ranges over which mineral assemblage could be formed

166
Q

how are petrogenetic grids useful?

A

they allow use to set limits for temperature and pressure during formation

167
Q

are there limits to petrogenetic grids’ usage?

A

YES
- cannot determine many of the minerals present in metapelites

168
Q

what are tie-lines representing in petrogenetic grids?

A

indicate stable minerals

169
Q

can tie lines in petrogenetic grids change?

A

YES
can vary depending on bulk composition

170
Q

what are tie line in Thompson projections?

A

they represent equant reactions

171
Q

what are Thompson projections?

A

tie lines join coexisting phases for just one possible mineral assemblage

172
Q

what are migmatites?

A

igneous/metamorphic rock mixed together

173
Q

how do migmatites form?

A

high temperatures cause metamorphic rocks to melt.

174
Q

what is the geothermometer GARB?

A

geothermometer for coexisting garnet and biotite

175
Q

what is the geothermometer GARB dominated by?

A

GARNET AND BIOTITE

176
Q

how accurate is the geothermometer GARB?

A

+- 50 DEGREES

177
Q

what is the geobarometer GRAIL?

A

reaction of:
Alamandine+Rutile=illimenite+Kyanite+quartz

178
Q

how accurate is the geobarometer GRAIL?

A

within 0.05 GPa

179
Q

STUDY

prograde-retrograde trajectories

A
180
Q

hydrothermal processes at divergent margins

A
  • hydrothermal alteration
  • most new rock is produced at M.O.R

GEOS 3464 EARTH MATS (3 decks)

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