1
Q
What are the three components of the earths structure?
A
- core (inner and outer)
- Mantle (upper and lower)
- Lithosphere (crust and uppermost mantle)
2
Q
What is the lithosphere?
A
- the ‘rock sphere’
- contains the igneous, sedimentary and metamorphic rocks
- variable thickness
- forms a semi-rigid tectonic plate
3
Q
What are the two types of crust? What are their differences?
A
- oceanic
- higher density, but thinner
- mafic materials
- silica and magnesium (SiMa) - continental
- lower density, but thicker
- felsic
- silica and aluminium (SiAl)
4
Q
What is plate tectonic theory? the basic concepts?
A
- a unifying idea that connects continental drift, sea floor spreading, seismic activity, crustal structure, volcanism, and resource distribution
- basic concepts of it is that there is a thin rigid lithosphere that is broken into a series of plates atop a mobile convecting asthenosphere
- plates move independently driven by mantle convection
5
Q
How does resource distribution connect to plate tectonic theory?
A
- different resources available in different areas due to plate tectonics
- resources available in areas where they shouldn’t be, because of our current day
- ex. Halite in Germany and Poland
- doesn;t make sense now- as Europe has a cooler climate. This suggests that Europe used to have a hotter climate - it was further south
6
Q
What are the three types of plate boundaries? explain ?
A
- divergent (2 plates spreading away from each other, constructive)
- convergent (2 plates moving toward each other/subducting - destructive)
- transform (2 plates sliding past each other)
7
Q
What are divergent plate boundaries?
A
- fractures in the lithosphere where two plates move apart
- dense mafic magma upwells along the rift
- creates thin dense oceanic crust
- causes deep abyssal plains
- ex. midatlantic ridges (like in iceland, or east african rift)
8
Q
What is interesting about rift valleys?
A
- they are essentially very young rifts
- create weird lavas due to very partial melting
- carbonatite (carbon and oxygen) lava
9
Q
What are oceanic convergent plate boundaries?
A
- destructive boundaries
- oceanic lithosphere forced beneath continental lithosphere or other oceanic lithosphere
- causes a subduction zone, lithosphere descends into asthenosphere
- creates ocean trenches
- felsic and intermediate volcanism
- creates island arcs and mountain uplift, also major earthquakes
10
Q
What are continental-continental convergent boundaries?
A
- destructive boundaries
- where continental lithospheres are forced together, large mountains are created
- continental crust too buoyant to subduct
- folding, faulting, and metamorphism occurs
- ex. uplift of himalayas, uplift of rockies
11
Q
What are transform plate boundaries?
A
- strike-slip
- plates slide past one another
- often link off-set constructive margins
- high earthquake potential
- creates ocean ridges, faults
- ex. san andreas fault
12
Q
How are felsic/grantitic intrusions formed? (igneous processes)
A
- formed from destruction of plate boundaries
- partial melt of subducting oceanic crust
- felsic melt is much less dense than surrounding crust, migrates upwards via stoping
- melt stabilizes
- slow cooling permits magmatic differentiation
- slow crystallization to produce coarse-grained materials
13
Q
What is ‘stoping’ movements?
A
- how felsic melt migrates upwards thru surrounding crust
- when magma moves up buoyantly, moves thru fractures, melts material on the way, the the entire magma body moves up
14
Q
What is the resource potential of felsic/granitic intrusions?
A
- important for emplacing hydrothermal and porphyry-type deposits
- minerals such as copper, gold, silver, zinc, lead and tin all settle near or in felsic igneous deposits
- many dissolved elements carried in hot fluids into faults and fractures surrounding granite batholith, dissolved copper, zinc, silver, etc. Minerals are precipitated in vein networks
15
Q
what are porphyry-type deposits?
A
- where dissolved elements are carried in hot fluids into faults and fractures surrounding granite batholith
- cooling, decrease in pressure, reaction with country rock may cause steam explosions/expansions, creating more fractures
- solubility decreases, minerals precipitate into the vein network
- creates literal ‘veins’ of minerals (such as gold)
16
Q
What are pegmatites?
A
- felsic/granitic intrusions
- very coarse grained granites formed at the margins of fluid-rich granitic intrusions
- apatite, beryl, spodumene
- major economic sources for these elements
17
Q
how are mafic/basaltic intrusions formed?
A
- formed by mid ocean ridges, constructive plate boundaries and mantle plum hotspots
- partial melt of the mantle
- extrusive basalts have little mineral potential
- intrusive basalts made due to slow cooling mafic magmas and thus are higher potential
- fall out of heavy minerals in sequence to bottom of the magma chamber produces stratified intrusion
18
Q
What are some potential resources of mafic/basaltic intrusions?
A
- dunite as a source for olivine
- metal sulfides formed during late-stage crystallization, sink to bottom of magma chambers and form rich deposits of iron, nickel, and copper sulfides
- magma may become saturated in chromium
19
Q
What is metamorphism?
A
- the alteration of preexisting rock
- original compounds and or textures have been transformed
- solid state process
- result of high temperature and/or pressure
- may cause foliated or unfoliated rocks
20
Q
What are foliated rocks? unfoliated?
A
foliated: mineral grains align themselves to differential pressure, layered appearance. formed from differential stress and re-orientation of mineral grains perpendicular to that stress
unfoliated: mineral grains grow into each other, equal pressure, massive appearance. alteration due to temperature with limited differential stress
21
Q
What are metamorphic grades? how do we determine this?
A
- degree of alteration from parent rock (protolith)
- depends on extent of heat and pressure
- higher heat and pressure = higher grade (typically larger crystal size and more developed foliation)
- new minerals form at different grades of metamorphism
22
Q
what are some common foliated rocks? (in order of least metamorphized to most)
A
slate –> phyllite –> schist —> gneiss
23
Q
what doe we use slate for?
A
- construction and roofing
24
Q
What are some common non-foliated metamorphic rocks?
A
- quartzite
- marble
- amphibole
- hornfels
25
What is regional metamorphism? Explain the typical conditions and some examples
- it is large scale metamorphism
- associated with mountain-building events
- major heating and differential stressing of rocks during continental collisions, and continental metamorphism
- causes mechanical deformation
- ex. alps, himalaya, appalachians
26
What are some resources we get from regional metamorphism ?
slate, phyllite, schist, gneiss = construction, decorative tiles, countertops
marble and quartzite = dimension stone, sculpture
garnet = used in abrasives, ceramics
kyanite = ceramics
27
What are some metamorphic settings?
- regional metamorphism
- contact metamorphism
28
What is contact metamorphism
- alteration of rock immediately in contact with intruded igneous rock
- smaller scale than regional metamorphism
- less pressure involved
- highly dependent on release of hydrothermal fluids
- typically no foliated rocks
29
What are skarns? Where do they occur?
- metalliferous ores (skarns- carbonate replacement)!
- these occur at margins of felsic intrusions
- iron oxides, copper, lead, zinc, iron sulfides, gold and silver
- occurs when felsic magma intrudes into limestone
30
What are some resources of contact metamorphism?
- metalliferous ores (skarns)
- precious stones and abrasives (beryl, corundum)
31
What is weathering?
- an in situ breakdown or alteration of rocks and minerals
- depends on the intrinsic properties of rocks
- also depends on environmental variables
- can be mechanical or chemical
32
What are intrinsic properties of rocks that may influence weathering?
- mineralogy/chemical
- strength of cementation
- rock structures and loading histories
- thermal expansion rates and specific heat capacity
33
what are environmental variables that may influence weathering
- temperature variability
- moisture availability
- rain/ground/soil water pH
- vegetation
34
What are types of mechanical weathering?
- unloading
- crystal growth
- thermal stressing
35
What is unloading
- type of mechanical weathering
- brittle expansion of unloaded rocks
- spalling and exfoliation
36
What is crystal growth?
- salt formation in cavities, mineral grain boundaries
- ice formation with freeze-thaw cycles
37
what is thermal stressing?
- differential expansion-contraction of rocks and minerals
- solar heating and cooling, fire, lightening
38
What is the net effect of mechanical weathering?
- produces sediment
39
What types of chemical weathering?
- any changes in minerals thru addition or subtraction of chems
- dissolution
- hydrolysis
- oxidation
40
What is dissolution? (in terms of chemical weathering)
- acidic rainwater dissolves calcium carbonate
- water saturated in calcite can be re-precipitated
41
what is hydrolysis?
- H ions and H2O combine with K feldspar to produce kaolinite (china clay)
- granular disintegration of granites (feldspars and micas to clay minerals, resistant quartz left behind)
42
What is oxidation? (in terms of chemical weathering)
- reaction of ferromagnesian minerals with free oxygen
- oxidation of granites (felsic) and mafic rocks
43
What are some weathered products that we use as resources?
- soils (mechanical and chemical breakdown products)
- kaolinite (hydrothermal modification of granites)
- bauxite (aluminum ore)
44
What is kaolinite? how does it form? what do we use it for?
- type of 'china' clay!
- hydrothermal modification of granites
- weathered feldspars and micas turn to clay minerals
- we use it for ceramics, toothpaste, food, cosmetics
45
How is bauxite formed?
- 3 minerals together
- heavy, tropical weathering leaches out all the mobile minerals
- leaves residual mass enriched in aluminum hydroxides
46
What is deposition?
- a reduction in energy, where materials fall out of suspension
- sediments sorted according to grainsize and density of materials
46
What is entrainment?
- particles picked up by moving fluids
- size of particles entrained depends on the energy of the system
- fast flowing = bigger grains, gentle stream = smaller grains
47
what is transportation?
- sediment moved from original location
- different grain size transported depending on energy
- different types of 'loads' depending on size of grains (solute, suspended, bed loads)
- transport rounds and reduces size of grains
48
what are some examples of erosion and deposition products as resources?
- aggregates - unconsolidated deposits sand and gravel (some of the most important materials for construction, concrete and roads)
- placer deposits - dense ore minerals concentrated by fluvial sorting processes (typically gold, diamonds, tin, etc)
49
what is diagenesis?
- the physical and chemical processes that affect sedimentary materials after deposition and before metamorphism and between deposition and weathering.
- low temp and low pressure modification of sedimental including recrystallization and cementation - lithification
50
What is regolith?
- blanket of fractured weathered rock and soil at the earths surface
51
What are the economic importance of shallow subsurface processes? why do we care?
- Aquifers may contain various dissolved soilds, such as ions
- organic breakdown of sediments or organic molecules increases the ration of carbon to hydrogen (creates cellulose to coal, and marine plankton to petroleum/oil)
52
What are some marine-specific processes that we use as resources?
- limestone formation (coral reef lithified to produce limestone, we then use this for construction materials)
- phosphate deposition ( phosphate debris (fish bones and teeth) accumulate, we can extract this for use in fertilizers)
- manganese/ polymetallic nodules (form on very deep ocean floors, can extract for nickel, cobalt and copper)
- iron sulphide black smokers (essentially hydrothermal vents pumping out super hot water, mixes with cold ocean water, precipitates iron sulfides that look like black smoke)
EASC 238 (Natural Resources)
flashcards
Decks in class (10)
# Cards
-
Topic 1: What are resources12
-
Topic 2: Resources in History and Culture18
-
Topic 3: Environment as a Resource (midterm 1 end)34
-
Topic 3: (midterm 2 start)12
-
Topic 4: Geologic processes and resource origins53
-
Topic 5: Fossil Fuel Energy55
-
Fossil fuel energy (after midterm 2)6
-
Topic 6: Nuclear fuels40
-
Topic 7: Alternative Energy50
-
Topic 8: Metals62
