Class Notes: Volcanism, Plate Tectonics, and Igneous and Sedimentary Rocks Flashcards
(93 cards)
1
Q
What are typical convergent boundary volcanoes?
A
Typically large composite volcanoes of any composition, mostly Intermediate.
2
Q
Where are convergent boundary volcanoes found?
A
On land as arc and chains of volcanoes or as island-arc volcanoes
3
Q
What causes convergent boundary volcanoes?
A
Subduction caused - subjecting lab heats due to increasing rural and frictional heat, melting in the 50-200 km depth range
4
Q
What are typical divergent boundary volcanoes?
A
mainly fissure eruptions along cracks (faults) caused by plate separation
5
Q
What causes divergent plate boundary volcanism?
A
pressure-release melting at ~50 km or less depth
6
Q
What are hot-spot volcanoes?
A
mantle plumes not necessarily directly related to main convection cells but superimposed on them.
7
Q
What are typical hot-spot volcano forms?
A
typically shield volcanoes of basalt
8
Q
How do hot-spot volcanoes track plate movement?
A
Plumes appear fixed and plates move over them, leaving chains of volcanoes tracking plate movement
9
Q
How do hot-spot volcanoes melt?
A
Pressure-release melting
10
Q
Where are common hot-spot volcanoes?
A
Hawaii
11
Q
What are two common examples of places with convergent boundary volcanoes?
A
Cascade Range (land arcs and chains), Aleutian Islands (island-arc volcanoes)
12
Q
What is an example of divergent boundary volcanism?
A
Iceland
13
Q
What are the 6 secondary effects of volcanism?
A
- acid rain
- particles in atmosphere
- CO2 in atmosphere
- friction between ash and air causes ionization of atmosphere
- landslides
- tsunami (s)
14
Q
What is acid rain caused by?
A
volcanic degassing
15
Q
What do particles in atmosphere cause?
A
(fine ash and find droplets of sulphuric acid) cause reflection of sunlight back to space causing climatic cooling
16
Q
What does CO2 in atmosphere cause?
A
Is a greenhouse gas and helps trap in the atmosphere sunlight reflected off the solid earth causing climatic warming
17
Q
What two things does friction in atmosphere cause?
A
- lightening storms
- insect disturbance
18
Q
What are the two types of landslides? What is the difference?
A
Rockslides = big chunk of rock--no water Mudflows = clay, sand, silt saturated with water and flows
19
Q
What are tsunamis?
A
- seismic sea waves
- large waves caused mainly by displacement of the sea floor 9and locally by landslides into ocean)
20
Q
What are the two main causes of tsunamis?
A
1) Caldera formation (formed quickly there is a rapid rush of sea water)
2) Sea-floor fault
21
Q
How high may tsunamis get up to?
A
greater than 200 m high
22
Q
What is the velocity of tsunamis?
A
800 km/hr
23
Q
Two types of tsunamis?
A
1) deep-water waves
2) shallow-water waves
24
Q
Tsunamis: wave length___, height___, velocity___ as they travel.
A
- decreases
- increases
- reduces
25
What are the 4 ways to predict a volcanic eruption?
1. mapping and dating volcanic products
2. til meters and inflation (if magma coming into volcano is causing it to swell)
3. earthquake monitoring (as magma rises it cracks the rock and creates little earthquakes)
4. gas monitoring (SO2 increase?)
26
What are intrusive?
injected as magma into country rock and freezes (crystallizes) in place, at depth, below the earth's surface.
27
What are the types of intrusive bodies (8)?
1. dikes
2. sills
3. laccoliths
4. plugs (pipes, spines, necks)
5. stocks
6. batholiths
7. magma chamber
8. pluton
28
What is a dike?
- tabular (sheet-like), discordant, commonly nearly vertical
- more common than sill
29
What causes a dike?
- crack developed and filled with magma
| - eroded
30
What time period are dikes from?
Precambrian
31
Do all volcanic arcs have dikes?
yes
32
What is sill?
tabular, concordant, commonly nearly horizontal
33
What happened to form a sill?
- magma injected into weaker rock
| - same composition as dikes
34
What is a laccolith?
sill with domain top, strata arched over top, discoid
| -form from sills where cooling magma is having trouble forming and country rock above gets domed
35
What is a volcanic plug (spine, pipe, neck)?
feeder pipe coming off dike, sill, magma chamber, lava or volcanic ash form mountain above then and they are eroded.
36
What is the difference between a stock and a batholith?
their size
37
If surface area on a map is < 1000 km2 it is a___
| If surface area on a map is > 100 km2 it is a ___.
- stock
| - batholith
38
What does most of the earth's continental crust (volume) consist of?
batholiths of various ages back to 3.7 Ga
39
What may the origin of batholiths and stocks be?
origin may be belting crust beneath them
40
What are continent builders?
batholiths and stocks
41
Approximately___% of Precambrian shield is made up of large stocks and batholiths injected into country rock.
60
42
What are magma chambers?
-a large volume of magma at depth that may act as a source for volcanoes, dikes, sills, or laccoliths
43
What do magma chambers freeze to form?
Freezes to form stocks, or large sills, laccoliths, or batholiths
44
How may magma chambers be fed?
May be fed by other connected magma chambers
45
What are plutons?
-large single-event intrusive bodies of any type (~ 100 km2)
46
Many___are single plutons, some are___. ___are___.
- stocks
- composite
- batholiths
- composite
47
What are big enough to call plutons? What are too small to call plutons?
- stocks, batholith, some sills and laccoliths, rarely dikes, are big enough to call plutons
- plugs are too small
48
Where are the 4 major batholiths of the Americas and ages?
- Coastal Rg. Batholith
- Sierra Nevada B.
- Peru B.
- All between 160-120 Ma
- Wathaman Batholith (1860 ma)
49
Why is the Wathaman Batholith a stitching pluton?
Because it is right in the middle of the trans-hudson orogen. Injected during the middle of that time and since it is a stitching orogen, this is a stitching pluton.
50
What are the 3 youngest batholiths related to?
Cordieran Orogenic belt because they are younger.
51
How long is the Wathaman batholith? What is it overlain by? What land feature (has to do with erosion) is here?
- just under 1000 km long
- overlain by paleozoic limestone
- unconformity here
52
What 2 things is intrusion and plate tectonics related to?
1) Convergent Plate boundaries
| 2) Divergent Plate boundaries
53
How is intrusion and plate tectonics related to convergent plate boundaries?
Relation to subduction -generated volcanism at convergent plate boundaries
- Volcanic plumbing system
a. magma chambers
b. related dikes and sills
54
How is intrusion and plate tectonics related to divergent boundaries?
Mainly dikes in tower ocean crust -- filling crack and faults generated by plate separation -- some of the sites are feeds to the DB volcanism
55
What types of batholiths are emplaced during orogeny?
granitoid
56
What are sun-orogenic plutons?
Are themes important intrusion (volumetrically) in the continental crust, and make up over half of the Earth's continental crustal material.
57
Wha are the two major sedimental rock types?
1) clastic
| 2) chemical and biochemical sediment
58
What are clastic sedimentary rocks?
Consists of rock or mineral fragments (grains); lithified to form sed. rock
59
What is the most common type of sed. rock?
clastic
60
What is chemical and biochemical sediment?
i) precipitated from solution by inorganic chemical process (e.g. cements, salt, potash)
ii) remains of organisms
- may be fresh (bones, shells), or altered (silicified wood), or highly altered (coal)
- elements extracted from solution by organisms (e.g. clam shells, corals, teeth, bone, wood).
61
What are some examples of environments where sediment is deposited?
river flood plains, deltas, lake beds, coral reefs, etc.
62
What are the 6 important properties of clastic rocks?
1) composition of grains or clasts
2) shape of fragments
3) size of fragments
4) structures present
5) porosity
6) permeability
63
What can the composition of clastic rocks be? What
mainly quarts; and of cements (e.g. silica; ferugenous)
64
What can the shape of fragments of clastic rocks baby from?
angular to rounded
65
What can the size of clastic fragments baby from?
boulders to clay
66
What is porosity (clastic)?
proposition of pore space
67
What does porosity depend on (clastic)?
shape of fragments, size of fragments, and cementation
68
What is permeability of clastic?
ability to transmit fluid (water, gas, or oil)
69
What does permeability depend on (clastic)?
depends on several things, notably the porosity
70
What will porosity and permeability vary with (clastic)?
degree of lithification
71
What are the 4 important properties of chemical and biochemical rocks?
1) composition
2) shape and size of crystals
3) porosity
4) permeability
72
What does the composition of chem and biochem sed. rocks depend on?
environment
73
When do chemical and biochem rocks have low porosity?
very low in crystalline chemical sed. such as salt.Wha
74
When is permeability low in chemical and biochemical sed. rocks?
very low in crystalline chemical sed. such as salt.
75
What are the steps for sedimentary rocks to form?
1) erosion of source rock
2 transportation (e.g. rivers)
3) deposition of new sediment
4) preservation (burial, lithification of rock)
5) erosion and uplift
6)exposure of sed. rock to Earth's surface
7) erosion and recycling of material
76
Where does weathering occur?
| Two types?
- in place (chemical reaction of rock to air, water)
1. chemical alteration
2. physical alteration
- some material may be dissolved and then transported in solution (by chemical means or by organisms --biochem--fossils)
77
What is erosion?
Removal of rock material that enters transportation system (river, wind, ocean, glaciers). All this material will be dumped somewhere. Anytime air, water, ice, in motion we find erosion.
78
What 7 things do geologists study to understand the history of sedimentary rocks?
1. age of deposition
2. deposition mechanism
3. depositional environment
4. preservation
- burial
- lithification
5. transportations process
- rivers
- waves, ocean currents
- solution
- wind
6. source
7. economic value
79
What are the two types of differential weathering?
1) Resistent - cliff forming strata (limestone)
| 2) Recessive strata- shale
80
What does differential weathering control?
A control on scenery: cliffs, slopes, and valleys.
81
What is weathering?
Where rock or even unlithified material (sed. or pyroclastic) is exposed but does not prod --- it "weathers" however. Mostly chemical alteration by water (in air) and shallow groundwater.
82
What produces soil?
weathering
83
What are the types of detrital sedimentary rock?
- siliciclastic (silt, sand, gravel, siltstone, sandstone, conglomerate)
- clay (claystone, shale, mudstone)
84
What are detrital/chem/biochem sed. rocks?
- carbonate (limestone [CaCO2], dolostone [Mg present])
| - other ([Chert-SiO2] [potash-salt], coal, gypsum).
85
When will detrital carbonate form?
if carbonate rock exposed a surface and eroded it will form carbonate silt and sand
86
What three things can carbonate be?
1) chemical
2) biochemical
3) detrital
87
CO3 =
carbonate
88
What are eroded source rock products 9what becomes the new sediment)?
-detrital grains (silt, sand, pebble, boulders)
-dissolved material (chemical sed. rocks)
clay (and cement)
89
What are the 2 types of deposition of sed. rocks (what is its form)?
1) clastic (mostly)
| 2) crystalline (if deposition is by chemical precipitation) --> e.g. evaporation
90
Why is sedimentary rock economically important (list)?
- building stones
- groundwater
- petroleum (H2S)
- gypsum --> gyproc
- limestone --> cement, concrete
- halite - salt
- sylvite KCL potash
- sodium sulphate - fertilizer
- sulphur - construction (sand and gravel)
- placer gold
- placer diamond
91
What are the 6 types of rocks/formations that are used as aquifers?
1) porous sandstone
2) pores gravels (conglomerates)
3) limestone
4) vesicular lava
5) pyroclastic
6) cracks
92
What is groundwater responsible for?
cementing of sands, limestones, etc. as chemical precipitations take place
93
What do concretions and nodules form from?
groundwater
