Geology Final Exam Flashcards

1
Q

A rock whose original minerology and/or texture has changed due to pressure and temperature WITHOUT melting

A

metamorphic rocks

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2
Q

protolith of blue schist

A

basalt

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3
Q

protolith of garnet-staurolite schist

A

shale

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4
Q

increase in temperature with increasing depth

A

geothermal gradient

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5
Q

average geothermal gradient

A

30C/km

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6
Q

minerals are stable over restricted conditions of T (and P)

A

geothermometry

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7
Q

pressure gradient

A

0.3-0.4 kbars/km

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8
Q

pressure in all directions (analogous pressure under water)

A

confining pressure

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9
Q

force exerted in a specific direction .causes folding, deformation, and minerals to align.

A

directed pressure

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10
Q

minerals are stable over restricted conditions of P (and T)

A

geobarometry

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11
Q

fluids can add or remove chemical components resulting in changes in the bulk composition

A

mesosomatism

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12
Q

protolith for gneiss

A

granite

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13
Q

protolith of marble

A

limestone

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14
Q

set of flat or wavy parallel planes produced by deformation

A

foliation

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15
Q

Foliated rocks are classified by

A
  1. crystal size
  2. nature of foliation
  3. segregation of minerals into light and dark bands
  4. metamorphic grade
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16
Q

order of increasing grade in metamorphic rocks (increasing metamorphic grade)

A

slate, phyllite, schist, gneiss, migmatite

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17
Q

heat from igneous rock intrusions metamorphoses surrounding rock (small scale)

A

contact metamorphism

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18
Q

heat and pressure are imposed over large areas of the crust (large scale).i.e. mountain belts. result from changes in P and T. rocks are deformed (folded and faulted). Formed from collision of tectonic plates.

A

regional metamorphism

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19
Q

metasomatism of the oceanic crust by hydrothermal circulation

A

hydrothermal (seafloor) metamorphism

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20
Q

meteorite impact

A

shock metamorphism

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21
Q

groupings of rocks of different mineral composition based on temperature and pressure. Minerals in a rock are clues to the history (P and T) of the rock.

A

metamorphic facies

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22
Q

the set of all P-T conditions experienced by a rock during its metamorphic history

A

Pressure-Temperature Path

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23
Q

increasing pressure and temperature

A

prograde

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24
Q

decreasing pressure and temperature

A

retrograde

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25
Q

pulls rocks apart,(stretching) at divergent boundaries.
rift valleys.

A

tensional forces

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26
Q

pushed rocks together (squeezing and shortening), at convergent boundaries.
mountain belts.

A

compressional forces

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27
Q

pushes either side of a formation in opposite directions, at transform boundaries.
i.e. san andreas fault

A

shearing forces

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28
Q

compressive features

A

folding, reverse/thrust faulting

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29
Q

tensional features

A

stretching, thinning, and normal faulting

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30
Q

shearing features

A

shearing, strike-slip faulting

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31
Q

minor internal strain, catastrophic break

A

brittle

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32
Q

smooth, continuous plastic deformation

A

ductile

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33
Q

folding, stretching, thinning, shearing

A

ductile

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34
Q

reverse, normal, strike-slip faulting

A

brittle

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35
Q

low confining P
low T
high strain rate
low water content

A

brittle

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36
Q

high confining P
high T
low strain rate
high water content

A

ductile

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37
Q

where do brittle deformations occur?

A

shallow crust

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38
Q

where do ductile deformations occur?

A

deep crust

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39
Q

the direction of the intersection of a rock layer with a horizontal surface

A

strike

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40
Q

angle at which the bed inclines from the horizontal (down and to the right of strike)

A

dip

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41
Q

fracture with no offset

A

joint

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42
Q

fracture with offset

A

fault

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43
Q

the wall that is below feet

A

footwall

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44
Q

FUN (Footwall Up Normal)
drops younger rocks down against older rocks (footwall older than hanging wall). divergent boundaries. found in rift zones.

A

normal faulting

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45
Q

FDR (Footwall Down Reverse)
puts older rocks on top of younger rocks (footwall younger than hanging wall). convergent boundaries.

A

reverse faulting

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46
Q

repeated sequences of large lateral displacement

A

thrust faulting

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47
Q

side to side movement, can still have footwalls or hanging walls

A

strike-slip faulting

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48
Q

a convex-upward fold whose core contains the older rocks (mountain shaped)

A

anticline

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49
Q

a concave-upward fold whose core contains the younger rocks (valley shaped)

A

syncline

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50
Q

an imaginary surface that divides a fold as symmetrically as possible

A

axial plane

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51
Q

the line made by the length-wise intersection of the axial plane with the beds

A

fold axis

52
Q

fold with a non-horizontal fold axis

A

plunging fold

53
Q

limbs dipping symmetrically away form axial planes

A

symmetrical folds

54
Q

one limb that dips more steeply than the other

A

asymmetrical folds

55
Q

limbs that dip in the same direction. one or both limbs are tilted beyond vertical.

A

overturned folds

56
Q

a broad circular anticlinal structure, with the beds dipping radially away from a central point

A

dome

57
Q

a broad circular synclinal structure, with the beds dipping radially toward a central point

A

basin

58
Q

the occurrence of one event in relation to another

A

relative dating

59
Q

the number of years that have passed from the event until now

A

absolute dating

60
Q

newer ones were formed on top of older ones

A

principle of superposition

61
Q

sediments are deposited in nearly horizontal beds

A

principle of original horizontality

62
Q

geologic features that cut across rock must be younger than the rock they cut through

A

principle of cross-cutting relationships

63
Q

objects enclosed in rock must be older than the time of rock formation

A

principle of inclusions

64
Q

layers are continuous until encountering an obstruction

A

principle of lateral continuity

65
Q

layers of sedimentary rocks contain fossils in a definite sequence

A

principle of faunal sequence

66
Q

surface between two layers that was not deposited in an unbroken sequence; record of missing time

A

unconformity

67
Q

younger sediments rest upon the eroded surface of tilted or folded older rocks

A

angular unconformity

68
Q

an unconformity between beds that are parallel

A

disconformity

69
Q

an unconformity between stratified rocks above and unstratified igneous or metamorphic rocks below

A

nonconformity

70
Q

same # protons, different # neutrons

A

isotope

71
Q

undergo spontaneous decay to form atoms of another element (parent isotope)

A

radioactive isotopes

72
Q

undergo spontaneous decay to form atoms of another element (daughter isotope)

A

radiogenic isotopes

73
Q

How to date igneous rocks?

A

age of crystallization

74
Q

How to date metamorphic rocks?
yes; new mineral grows with only parent atoms or heating releases the daughter and resets the clock.
no; heating is not sufficient to reset clock.

A

age of metamorphism (not age of original rock)

75
Q

How to date sedimentary rocks?

A

Date igneous intrusions in sedimentary rocks.
Date volcanic ash layers.
Use fossils.

76
Q

Age of the earth is known from

A

meteorites and moon

77
Q

low density silicate materials (O, Si, Al, K)

A

crust

78
Q

40 km thick
density: 2.8 g/cm^3

A

continental crust

79
Q

7 km thick
3.0 g/cm^3

A

oceanic crust

80
Q

less dense continental crust floats higher on denser mantle than oceanic crust

A

isostatic balance

81
Q

most of the planet. high density silicate materials (O, Si, Mg, Fe, Ca, Fe).
density of 3.4 g/cm^3.
SOLID, GREEN, ULTRAMAFIC

A

mantle

82
Q

upper 100 km layer that is strong and rigid

A

upper mantle

83
Q

lower 100 km is weak and deformable, ductile

A

lower mantle

84
Q

mostly Fe, but also Ni, S, O.
LIQUID because of temperature.
density of 11 g/cm^3

A

outer core

85
Q

mostly Fe, but also Ni.
SOLID because of temperature.
density of 13 g/cm^3

A

inner core

86
Q

crust and upper mantle (100 km).
relatively cold, strong, rigid

A

lithosphere

87
Q

weaker part of the upper mantle, hot, weak, ductile

A

asthenosphere

88
Q

basalt is extruded at MORs. basalt records the magnetic field at the time of cooling. crust moves away from the ridges and becomes older.youngest near ridges and oldest near continent.

A

sea floor magnetic anomalies

89
Q

occur at zones of upwelling mantle. produces new oceanic crust. basaltic volcanism. small, shallow, earthquakes. normal faults, high heat flow. (mid ocean ridges)

A

divergent boundaries

90
Q

explosive andesitic volcanism. intrusion of granite at depth. large earthquakes, shallow to deep. metamorphism, folds, thrust faults. (subduction zones)

A

convergent boundaries

91
Q

no igneous activity. no metamorphism. large, shallow earthquakes. strike-slip faults.

A

transform boundaries

92
Q

attraction of oppositely charged ions, intermediate strength (halite)

A

ionic bonding

93
Q

electron sharing, very strong (diamond)

A

covalent bonding

94
Q

weak electrical bonding, intermolecular bonding (water)

A

van der waals bonding

95
Q

naturally occurring, crystalline substance, inorganic, specific chemical composition

A

minerals

96
Q

how to id rocks

A

mineralogy, texture

97
Q

form when magma erupts at the surface, rapidly cooling to fine ash or lava and developing tiny crystals. fine-grained rocks.

A

extrusive igneous rocks

98
Q

crystallize when molten rock intrudes into un-melted rock masses in earth’s crust. coarse-grained rocks

A

intrusive igneous rocks

99
Q

low silica content, darker

A

mafic

100
Q

high silica content, lighter

A

felsic

101
Q

result from explosive volcanic ejection

A

pyroclastic material

102
Q

lithified volcanic ash

A

tuff

103
Q

rock with two stages of cooling; slow cooling and fast cooling

A

porphyr

104
Q

how do rocks melt

A

decompression, and addition of water

105
Q

what most likely causes melting at divergent boundaries

A

decompression

106
Q

what most likely causes melting at convergent boundaries

A

addition of water, increase in temperature

107
Q

melts are always more than their parent

A

felsic

108
Q

causes wide range of composition of igneous rocks

A

partial melting, fractional crystallization, magma mixing, assimilation

109
Q

mafic minerals crystallize at higher temperatures than felsic minerals. mafic minerals crystallize first from cooling magmas. high temperatures = faster crystallization

A

bowen’s reaction series

110
Q

provide a record of history

A

sedimentary rocks

111
Q

process by which rocks are broken down. physical and chemical.

A

weathering

112
Q

process by which rocks are moved after breaking down

A

erosion

113
Q

physically transported rock fragments produced fro

A
114
Q

physically transported rock fragments produced from weathering of preexisting rocks (sandstone/shale)

A

clastic sediments

115
Q

direct, chemical deposition typically in marine settings (limestone, evaporite)

A

chemical and biochemical sediments

116
Q

selection of clasts according to particle size

A

sort

117
Q

more mafic rocks tend to weather

A

faster

118
Q

gravitation balance that determines elevation

A

isostasy

119
Q

elevation is function of

A

thickness and density

120
Q

pressure at the base of various parts of the curst is equal. to have the same pressure underneath and different densities, the thickness differs.

A

principle of isostasy

121
Q

magma transferred to continents at subduction zones (increase continent size)

A

magmatic addition

122
Q

buoyant fragments of crust attached to continents due to plate motions (increase continent size)

A

continental accretion

123
Q

mountain building process of folding, faulting, magmatism, and metamorphism

A

orogeny

124
Q

vertical motions of largely flat lying rocks without faulting or significant folding

A

erogeny

125
Q

general up or down warping of the crust with no faulting or folding.

A

epeirogeny