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Geohazard > earth materials > Flashcards

earth materials Flashcards

1
Q

It is the transition zone between
SIAL (silica aluminum), upper crust and SIMA
(silica magnesim ), lower crust

A

Conrad Discontinuity

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2
Q

discontinuities in the layers of earth

A

co
mo
re
gu
le

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3
Q

_________ are composed largely of dark colored mafic rocks enriched in _____ of _____, ____, and _____ relative to average crust

A

oceanic crust ; oxides ; iron, magnesum, and calcium

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4
Q

Composed largely of dark colored, mafic rocks enriched in oxides of magnesium, iron and calcium
( FeO and CaO) relative to average crust

A

oceanic crust

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5
Q

thickness of oceanic crust (depth to moho)

A

5-7 km

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6
Q

under some oceanic islands, oceanic crust can extend its thickness up to:

A

18km

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7
Q

primary rocks found in oceanic crust

A

basalt and gabbro

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8
Q

t or f: oceanic crust are older relative to the age of the earth

A

F (younger)

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9
Q

slices of ocean crust thrust onto continental margins

A

ophiolites

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10
Q

can be generalized as granitic in composition enriched in K2O, Na2O, and SiO2

A

continental crust

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11
Q

continental crust is enriched in oxides of:

A

Potassium, Sodium, and Silica

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12
Q

oldest well documented continental crust

A

4.03 Ga

from the northwest territories of canada

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13
Q

t or f: continental is thicker than oceanic crust

A

T

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14
Q

the great age of some continental crust results from its

A

buoyancy

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15
Q

silica composition of continental crust

A

approximately 60%

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16
Q

silica composition of oceanic crust

A

approx 50%

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17
Q

thickness of continental crust

A

30 km, under mountains is 80 km

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18
Q

age of oceanic crust

A

up to 180 Ma, 3.5% of earth’s history

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19
Q

age of continental crust

A

up to 4000Ma, 85-90% of earth’s history

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20
Q

t or f: oceanic crust have relatively lower surface elevation than oceanic crust

A

t

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21
Q

oceanic crust are mostly submerged _____sea level while continental crust are mostly emergent _____ seas level

A

below ; above

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22
Q

thickness of earth’s mantle

A

2900 km

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23
Q

radius of the earth

A

6370 km

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24
Q

earth’s mantle constitutes how many percent of earth’s volume

A

approx 83%

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25
Q

silica composition of earth’s mantle

A

40-45%

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26
Q

the earth’s mantle has an _____ composition

A

ultrabasic

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27
Q

sublayers of earth’s mantle

A

upper mantle and transition zone

lower mantle

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28
Q

MgO content of mantle

A

30-40%

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29
Q

depth of low velocity zone

A

100-250 km

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30
Q

marks the contact between strong lithosphere and weak asthenosphere

A

low velocity zone

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31
Q

the uppermost part of the mantle and the crust together constitute the relatively rigid _____

A

lithosphere

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32
Q

the asthenosphere is more _____ and _____, rather than rupturing when subjected to stress

A

plastic ; flows slowly

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33
Q

lithosphere is strong enough to _____ in response to stress

A

rupture

34
Q

minerals found in transition zone

A

ringwoodite and garnet

35
Q

minerals found @660km depth

A

perovskite and periclase

36
Q

minerals found @410km depth

A

olivine, wadleysite

37
Q

major minerals found in mesosphere

A

perovskite and periclase;
ilmenite;
ferrite;
stishovite;
magnesiowustite;

38
Q

complex zone near the core-mantle boundary, where anomalous seismic signals are common

A

D” layer

39
Q

our knowledge of the deep mantle continues to expand largely based on ________ deep within the earth

A

anomalous seismic signals

40
Q

D’’ discontinuity ranges from

A

130-340 km

41
Q

heat sources in the earth

A
  1. residual heat from formation
  2. frictional heat
  3. decay of radioactive elements
42
Q

these sporadic ULVZ may be related to the formation of _______within the lower mantle

A

deep mantle plumes

43
Q

percent composition of iron in earth’s core

A

approx 85%

44
Q

percent composition of nickel in earth’s core

A

5 %

45
Q

density of outer core

A

10-12 g/cm^3

46
Q

density of inner core

A

appox 13g/cm^3

47
Q

refers to the non-uniform seismic velocities in the core

A

seismic anisotropy

48
Q

amount of heat that can arise from accretion of small bodies, forming proto-earth

A

10,000 kelvins

49
Q

heat produced by descent of iron-rich materials

A

2,000 kelvins

50
Q

long-lived radioactive isotopes

A

235U, 238U, 232Th, and 40K

51
Q

goldschmidt classifications

A

lithophile-rock loving
siderophile - iron loving
chalcophile - sulfur loving
atmophile - gas loving

52
Q

what does HREE/LREE stand for?

A

Heavy Rare Earth Elements;
Light Rare Earth Elements

53
Q

what does LILEs stand for?

A

Large Ion Lithophile Elements

54
Q

what does LFSEs and HFSEs stand for?

A

Low Field Strength Elements ; High Field Strength Elements

55
Q

the substance of which any physical object is composed of

A

matter

56
Q

controlling factors of state of matter

A

temperature and pressure

57
Q

layers of electrons that orbit around the nucleus are called

A

orbitals or energy-level shells

58
Q

an atom that has gained or lost electron

A

ion

59
Q

smallest particle that defines an element

A

atoms

60
Q

consists of elements that combine in a specific ratio

A

chemical compound

61
Q

covalent bonds have electronegativity of

A

less than 1.68

62
Q

ionic bonds have electronegativity of

A

greater than 1.68

63
Q

4 types of bonding

A

covalent
ionic
metallic
Van der Waals

64
Q

very weak bonding

A

Van der Waals Bonding

65
Q

what is a mineral

A

Naturally occuring
inorganic
homoenous solid
definite chemical composition
crystalline structure

66
Q

most abundant silica group

A

feldspar (plagioclase) 39%

67
Q

abundance of quartz

A

12%

68
Q

arrange silica in terms on increasing abundance

A

plag
ortho
quartz
pyroxene
(non silicates)
amphibole
mica
clays
other silicates

69
Q

involves circulation and exchange of elements and minerals within the ecosphere and its environment

A

biogeochemical cycle

70
Q

t or f: asthenosphere is solid but mobile

A

T

71
Q

depth of transition zone

A

410-660km

72
Q

depth of upper mantle from the crust

A

410km

73
Q

depth of lower mantle from the crust

A

660km

74
Q

depth of outer core from the surface

A

2900km

75
Q

depth of inner core from the surface

A

5150

76
Q

it is a strong rigid layer

A

lithosphere

77
Q

layers of ophiolite

A

layer 1 - sediments
layer 2 - pillow basalts and sheeted dikes
layer 3 - gabbro
layer 4 - layered ultramafic rocks

78
Q

depth of asthenosphere

A

100-660

79
Q

smallest quantity of a compound

A

molecule

80
Q

4 types of bonding

A

covalent
ionic
metallic
Van der Waals

81
Q

element abundances in the crust

A

46.6
27.7
8.1
5.0
3.6
2.8
2.6
2.1

Geohazard (25 decks)

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