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geology > midterm 2 > Flashcards

midterm 2 Flashcards

(49 cards)

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1
Q

earthquakes and their causes, what Have we used from them?

A

an earthquake is an episode of groundshaking

causes:
- fault motion **MAIN
- fracking (rock-breaking detonations)
- explosions (underground nuclear detonations)
- meteor impact
- landslides
- re-arrangment of atoms in minerals (in subduction zones bc of pressure

used seismic waves to understand the earth’s deep structure

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2
Q

elastic rebound theory

A

under pressure rocks will bend until they break, when they break they go back to their original shape but with a fracture

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3
Q

faults and their terminology

A

a fault is a fracture in the ground where one body has slid relative to the other due to forces in the earth
(ex: Istanbul Highway (TEM) near Ankara, Turkey)

head block: block of rock on top
footwall block: block of rock on the bottom

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4
Q

fault vs joint

A

joint: fracture in rock has no slippage
fault: fracture in rock, there is slippage

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5
Q

types of force that cause faults

A

compression: force from both sides (left and right), crust gets thicker vertically (crustal thickening)

tension: pulling apart the crust, crust gets thinner vertically, can cause mountains to form because creates basins separated by ranges
ex: SW usa, east african rift

shear: side to side motion, crust gets pulled angularly (rectangle to parallelogram), aka transform boundaries
ex: San Andreas fault

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6
Q

types of faults

A

normal faults:
- head block moves down
- force = tension

reverse faults:
- head block moves up
- force = compression

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7
Q

earthquake depth vs boundary

A

divergent & transform: shallow
convergent: deep

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8
Q

New Madrid Earthquakes

A

in/around missouri ~200 years ago (winter of 1811-1812)
maybe an old rifting spot that stopped
3 BIG shakes (8 or 9 Richter)
weird things: geyers of sand, silt erupting from ground

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9
Q

earthquakes that are not at boundaries

A
  • adjusments to lithosphere to volcanism
  • ancient collision zones
  • ancient rift zone
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10
Q

what caused the 2011 VA earthquake

A

slippage at an old reverse fault from formation of Pangea

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11
Q

body waves, surface waves, types and order

A

P => S => R & L
body:
- P (compressional) solid & liquid
- S (shear) solid
surface:
- R (rayleigh) like ocean
- L (love) side to side

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12
Q

types of earthquake scales

A

mercalli: very qualitative, based on what happens (feels like truck driving, liquids disturbed)

seisogram: depicts vert & horiz waves when they arrive (P, S, surface)

richter: base intensity on largest amplitude of each wave; logisitic scale

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13
Q

how can you determine location of earthquake from seismogram?

A

S-P interval (time between arrival P & S waves) is used to determine distance from the station. incr time = incr distance.
distance is drawn as a circle around the station => epicenter (specific location) is found from intersection of 3 circles

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14
Q

US Geological Earthquakes Hazards Map

A
  • Alaska: & Oregon OC-CC (reverse)
  • West Coast: transform boundary (shearing)
  • Utah: active rift (normal)
  • Wyoming: hotspot
  • Missouri/Arkansas: ancient rift (normal)
  • Appalachain Mts: old reverse faults
  • New York: glacial rebound earthquakes
  • South Carolina: hotspot where pangea rifted
  • Hawaii: hotspot
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15
Q

when rocks break how is energy released?

A

body and surface waves

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16
Q

deformation

A

the bending, breaking, stretching of rock

ex: Interior Plains (mid west) is super flat and undeformed [shales, sandstones, & limestones] can infer there used to be a shallow ocean

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17
Q

types of deformation

A

brittle (breaking):
- composition: covalent bonds
- lower pressure
- high rate of force (fast)
- lower temp

ductile (bending):
- composition: ionic bonds (ex: NaCl, micas)
- higher pressure
- slow rate of force (long time)
- higher temp
- strain = change in shape
- ex: clasts in quartzite stretched

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18
Q

types of ductile folds

A

folds are larger scale strain

anticline: old layer in coming thru middle, young layer sandwich

syncline: young layer middle, old layer hotdog

plunging: bump in carpet, but at a slope

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19
Q

how did appalachian mountains form?

A

formed from 3 collisions that created fold and thrust belt => reverse faults and plunging folds

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20
Q

why does granite form large joints at high altitude?

Study These Flashcards
A

granite is formed under high pressure, when exposed to low pressure it cracks

21
Q

relative age uses and types

Study These Flashcards
A
  • original horizontality: sediment deposited horizontally
  • lateral continuity: sediment layers are continuous
  • super position: youngest layer on top, oldest on bottom
  • cross cutting: geology that crosscuts rock is newer then the rock
  • inclusions: inclusions in rock are older than the rock
22
Q

unconformities

Study These Flashcards
A

gaps in dating of rocks (200ya, 300ya, - , 500ya)

causes: no sediment (no source material like mountains), erosion of gap layer

23
Q

absolute dating

Study These Flashcards
A
  • most based on radioactivity
  • C14 decay
  • U decay (U = parent, Pb = daughter)
  • Rb (Rb = parent, Sr = daughter)
    => when feldspar in GRANITE forms, it grabs rubidium thinking its K
  • needs minerals that:
    ===> don’t have any of the daughter element to start
    ===> trap the parent & daughter forever
    ex: Zircon for U & Pb
24
Q

half life formula and meanings

Study These Flashcards
A

N = N_0*(e)^(-λt)

N = # of parents now
N_0 = # of parents initially
λ = ln(2)/half life
t = years passed

25
wats da geo period order
phanerozoic protozoic archaen hadean phanerozoic: 0 - cenozoic - 64 64 - mesozoic - 252 252 - paleozoic - 541 cenozoic: - quarternary => 0.02 modern humans - neogene - paleogene => 30 Alps, 40 India, 66 K-Pg event mesozoic: - cretaceous - jurassic - triassic paleozoic: - permian - carboniferous - devonian - silurian - ordovician - cambrian youngest oldest
26
varves
annual bands of seasonal deposition in lakes layers: - coarse sand - fine silt, clay, organics - coarse sand - fine silt, clay, organics - repeated^^ influences: floods from melted snow => more coarse sand, using radioactivity (bomb pollution) to date sediment
27
why is papau new guinea significant to jim?
small region but over 800 langauges b/c separation by mnts. => SEPARATION BREEDS DIVERSITY
28
ice age
10% of earth covered in ice
29
what caused the devonian explosion?
continental continental collision created hella mountains => separation => diversity
30
what conditions for hydrocarbon formation?
- dead plankton - calm water (so they^ settle) - very low O2 (so reaction doesn't reverse) - a lot of sediment (ex: clay) (buries plankton) => when this layer gets buried and reaches 80C, its trnasformed into a source rock (ex: shale) w/ kerogen ==> when kerogen reaches 120C, it turns into oil; unless the source rock has a cap rock on top, the oil floats to the surface <0.1% of all marine organic matter will become a viable petroleum resource
31
what is the geological timeline for a perfect hydrocarbon formation environment
continental rifting => new ocean (warm & shallow) & sediment => perfect for hydrocarbon ex: mesozoic rifting of pangea in Middle East
32
oil shale
basically source rock, dirty & smelly, mostly black, kerogen wasn't heated to oil
33
coal
black, brittle, sedimentary rock [carbon, quartz, clay from a SWAMP] type: pete (plant matter) => ligmite => bituminous => anthracite (high grade) - high grade = generates most energy - difficult to mine, dirty to burn - TERRESTRIAL deposit, edge of continents
34
why was the paleozoic good for coal formation?
- collisions to make coal high grade - high oxygen for plants - continental flooding (buries swamps w/ sediment)
35
both fossil fuel qualities
both aka Coal & Hydrocarbons - limited supply - mining & extraction disasters - changes atmosphere composition - also coral bleaching (CO2 makes H2CO3 which is an acid)
36
why was the eastern usa in carboniferous good for coal formation
- near equator so hella warm & swampy - gets buried w hella sediment from flooding - crashes into africa (goof for high grade)
37
Uranium as an energy source
pros: - a lot left - little/no greenhouse emissions - naturally occurring - more energy potential than coal cons: - waste rock - needs hella water - nuclear waste - human error
38
strong force (nuclear energy term)
force holding together nucleus, released by firing neutrons at nucleus
39
ore
rock with concentrated metal-rich minerals (must be concentrated enought to be valuable to mine) - biological processes & climate change create valuable ore
40
aluminum
- 8% of crust - 10% of felsic and intermediate rocks - hydrolysis will dissolve feldspars in granite and leave Al ore - needs hella rain, warm climate, expose felsic igneous rock for hella long - bauxite is the primary Al ore (ancient tropical soils developed on felsic igneous rock)
41
iron
- 6% of crust - 30-60% of rock - first massive deposits created because photosynthesis started (HELLA O2 in water) - BIF = Proterozoic Banded Iron Formations (layers of magenetite and red hematite)
42
sulfide deposits
valuable metals (Pb, Cu, Au, Zn) bond with sulfur and form sulfide minerals magmatic: sulfide minerals crystallize quickly and sink to the bottom of the magma chamber ex: mine in Admiralty Island, Alaska black smokers: sulfide minerals in heated up seawater ejects from "chimneys" underwater, at divergent boundary
43
placer deposits
ore rock erodes, clasts containg native metals fall into a stream, stream concetrates the ore by separating the grains
44
chemical weathering to make aluminum
primary rock + CO2 + water = residual clay mineral + soluble stuff that leaches away (esp Si) residual clay mineral + leaching = Al2O3
45
mass wasting
erosion whose sole transport is gravity creep: gravity acting on particles, slow, on every sloping surface
46
angle of repose
loose granular material assumes a slope because of friction, the angle of repose is the steepest slope it can have influenced by water content, grain size, shape
47
causes of creep
bioturbation (animal burrowing), freeze/thaw (ground rising&falling), rainsplash (rain loosens particles)
48
controls on mass wasting
water: - depending on amount - binds particles with surface tension - saturated sedimenet will flow slope climate cohesion vegetation
49
what makes coastal cali susceptible to mass wasting hazards
semi arid climate => when it rains, BIG problem emergent coastlines => tectonically active region, coastline gets lifted and terraced, creates erosion structures earthquakes whose fault was La Conchita, CA? avocado ranch bc they didnt drain rainwater properly

geology (3 decks)

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