Test 3 Flashcards
1
Q
fault scarp
A
faults intersect the surface and produce a “step”
2
Q
normal fault
A
hanging wall slips down
3
Q
reverse fault
A
hanging wall slips up
4
Q
thrust fault
A
low angle reverse fault
5
Q
strike-slip fault
A
walls slip horizontally
6
Q
elastic-rebound theory
A
earthquakes occur because stresses build up, causing rock to bend elastically until either a new fault forms or a pre-existing fault slips, the bent rocks then straighten and vibrate
7
Q
focus
A
location where seismic waves first begin to be generated
8
Q
shallow-focus earthquake
A
top 60 km of earth
9
Q
intermediate-focus
A
60-300 km
10
Q
deep-focus
A
down to 660 km
11
Q
body waves
A
pass through the interior of the Earth
12
Q
surface waves
A
travel along the Earth’s surface
13
Q
compressional waves
A
particles move back and forth parallel to the direction the wave propagates
14
Q
shear waves
A
particles move back and forth perpendicular to the direction the wave propagates
15
Q
P-waves
A
primary compressional body waves
16
Q
S-waves
A
secondary shear body waves
17
Q
R-waves
A
Rayleigh surface waves that cause the ground to undulate up and down
18
Q
L-waves
A
Love surface waves that cause the ground to shimmy back and forth
19
Q
Earthquake intensity
A
the degree of ground shaking
20
Q
Earthquake magnitude
A
a # that represents the amount of energy released from the seismic source
21
Q
Moment magnitude
A
based on the amplitude of several different waves
dimensions of the slipped area
displacement that occurred
22
Q
Why do earthquakes occur in the Waditi-Benioff zone
A
shear between sinking lithosphere plate and surrounding asthenosphere
pull exerted by deeper part of the plate
23
Q
Earthquakes at continental rifts
A
normal faults
shallow earthquakes
24
Q
Earthquakes at collision zones
A
movement along thrust faults
25
Intraplate earthquakes
stress applied to the boundary of a plate can cause the interior to break suddenly at weak, pre-existing fault zones
26
The Severity of shaking depends on
magnitude of the quake
distance from the source
nature of the substrate at the location
wavelength of the earthquake waves
27
sediment liquefaction
happens in wet sand when shaking causes grains to settle together
pressure in the water filling the pores increases
water pushes the grains apart turning the sand into a slurry incapable of supporting weight
28
geologic structures
features produced by deformation
29
displacement
a change in location
30
rotation
change in orientation
31
distortion
a change in shape
32
Why do rocks deform brittle or ductile?
```
temp(warmer = more ductile)
pressure(more = more ductile)
deformation rate(slow=more ductile)
composition
```
33
joints
natural cracks
34
vein
mineral filled crack
35
dip-slip fault
displacement is parallel to a line going down the slipe of the fault surface
36
obliqua-slip fault
sliding occurs diagonally on the fault plane
37
fold
curve in the shape of a rock layer
38
limb
sides of the fold
39
hinge
a line along which the curvature of the fold is the greatest
40
axial surface
an imaginary plane that contained the hinge lines of successive layers and divides the fault in half
41
anticline
folds that have an arch like shape
42
synclines
folds with a trough-like shape
43
moncline
the shape of a carpet draped over a stair step
44
plunging fold
the hinge is tilted
45
dome
fold with the shape of an overturned bowl
46
basin
fold with the shape of an upright bowl
47
flexural-slip fold
a stack of layers bend and slip occurs between the layers to accommodate the bending with out creating gaps between layers
48
passive flow
the rock is so soft that it behaves like a weak plastic and slowly flows
49
fold-thrust belt
assemblage of thrust faults and associated folds
50
suture
the boundary between what had been separate blocks
51
exotic terrain
| accreted terrain
an incoming buoyant crustal block that becomes sutured to the overriding plate
52
isostacy
when the elevation of Earth's surface reflects the level at which the lithosphere naturally sets
53
orogenic collapse
mountains collapse when quartz-rich rocks become weak enough to flow ductilely
54
craton
crust that has not been effected by orogeny for at least the last billion years
55
shields
precambrian metamorphic and igneous rocks crop out at the surface
56
cratonic platforms
relatively thin layer of phanerozoic sediment covers the precambrian rocks
57
epeirogeny
the broad vertical movements that generate huge, but gentle, mid continent domes and basins
58
uniformitarianism
physical processes that operate in the modern world also operated in the geologic past
59
original horizontality
layers of sediment are deposited relatively flat
60
superposition
each layer must be younger than the one below and older than the one above
61
lateral continuity
sediments accumulate in continuous sheets
62
cross-cutting relations
if one geologic feature cuts across another, the feature that has been cut is older
63
baked contacts
an igneous intrusion "bakes" surrounding rocks so the rock that has been baked must be older than the intrusion
64
principle of inclusion
a rock containing an inclusion must be younger than the inclusion
65
index fossils
fossil species that are widespread but survived only for a relatively short interval of geologic time
66
unconformity
a boundary surface between 2 units which represents a period of non deposition and possibly erosion
67
angular unconformity
rocks below were tilted or folded before the unconformity developed
the angular unconformity cuts across layers and the orientation of layers below an unconformity is different from the layers above
68
non conformity
sedimentary rocks overly igneous rocks
69
Disconformity
an undersea sedimentary layer is exposed for some time, maybe eroded, and then sea level rises and new sedimentary layers are deposited
70
stratigraphic formation
an interval of layers composed of a specific rock type or group of rock types
71
correlation
relative the relative age of a strata in one location to that in another
72
hydrocarbons
Ex; Oil and gas
| chain0like or ring-like molecules composed of carbon and hydrogen atoms
73
Where do the chemicals that make up oil and gas come from?
Plankton
74
In what environment do fossil fuels form in?
oxygen efficient calm waters such as deltas and swamps
75
Oil shale
25-75% kerogen
76
Oil window
90-150 deg C
| 2-6 km
77
Gas window
90-225 deg C
| 2-9 km
78
Conventional reserve
hydrocarbons that could be pumped from the ground easily
79
Porosity
the proportion of the rock that consists of open spaces, pores
80
Permeability
the degree to which pore spaces connect
81
Reservoir rocks
They don't actually contain oil when the form
| Oil migrates upward from the source rock
82
Oil seep
if oil or gas escapes from the reservoir rock
83
1st part of a Trap: Seal rock
a relatively impermeable rock such as shale, salt, or limestone
84
2nd Part of a Trap
the seal and reservoir rock must be arranged in a geometry that localizes the hydrocarbons
85
Hydrofracturing
drillers pump a mixture of water, various chemicals, and sand into a drill hole at high pressure to enhance the permeability of the existing fractures around the hole
86
Unconventional hydrocarbon reserve
hydrocarbons cannot be extracted simply by drilling and pumping
87
shale oil or shale gas
huge quantities of oil and natural gas that remain in source beds of organic shale
88
bitumen
tar like heavy oil
89
tar sand
sandstone containing high concentrations of bitumen
90
Coal
a black, brittle, sedimentary rock that burns, consists of elemental carbon mixed with minor amounts of chemicals, quartz, and clay
91
Peat
compaction and partial decay of vegetation transforms into peat with up to 50% carbon
92
Type of coal by increasing temp
lignite, bituminous coal, and anthracite
93
Hubbert's peak
the peak production for a give reserve
94
Ore minerals
minerals from which metals can be extracted
95
Magmatic deposits
when a magma cools and solidifies, sulfide or minerals may crystallize in distinct bands
96
Hydrothermal deposits
Water circulates through a pluton, heats up, dissolves metal ions, then the ions precipitate out when the water cools
97
Secondary- Enrichment deposits
Water passes through old ore bearing rock, dissolves ions and deposits them elsewhere often more concentrated than the source rock
98
Residual mineral deposits
soil rich is iron and aluminum
