Unit 7 Geology

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Unit 7 Geology Mining Resources

• Chapter 14

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Theory of Plate Tectonics

• Explains and unifies many geologic theories
• 1960s
• Basically describes how the Earths crust is made
  of plates that move around on top of the upper
  liquid portion of the mantle

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Plate Tectonics and Evolution

• _______________________________ helps to explain
  how populations become separate species as the
  continents move apart

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Lithosphere
Asthenosphere
Oceanic ridge at a _______________________
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Trench
Volcanic island arc
Lithosphere
Rising magma
Asthenosphere
Subduction zone
Trench and volcanic island arc at a
__________________________________________________
___
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Fracture zone
Transform fault
Lithosphere
Asthenosphere
________________________________________________
connecting two divergent plate boundaries
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_________________________

• Materials are dissolved, loosened, or worn away
  from one part of the Earths surface to another

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___________________________

• Process that breaks down rocks into smaller
  pieces that can be eroded
• Mechanical (frost weathering)
• Chemical
• Biological

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Minerals

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Rocks

• Combination of minerals
• May be organic
• Can contain fossils

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Igneous Rock

• Forms when _______________________ cools and
  hardens
• Intrusive form INSIDE the crust
• Extrusive form on/ outside the crust
• Ex granite, lava rock

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Sedimentary Rock

• Formed from ______________________ that become
  compacted
• Ex coquina, sandstone, shale

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Metamorphic Rock

• Rock is subjected to high ________________
  ______________________________________
• Ex anthracite, marble, slate

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Volcanoes
Earthquakes
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Liquefaction of recent sediments causes
buildings of sink
Two adjoining plates move laterally along the
fault line
Earth movements Cause flooding in Low-lying areas
Landslides may occur on hilly ground
Shock waves
Epicenter
Focus
Earthquakes
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__________________________

• Caused by movement of tectonic plates
• P-waves and S-waves
• see earthquake activity

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___________________________
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extinct volcanoes
central vent
magma reservoir
magma conduit
Solid lithosphere
Upwelling magma
Partially molten asthenosphere
Volcanoes
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3 Types of Volcanoes

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___________________________

• To encourage mineral exploration and mining out
  West
• Anyone can buy public land (except parks or
  wilderness) by patenting it

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General Mining Law of 1872

• Must say they think there are minerals there and
  that they will spend at least 500 to improve the
  land for mineral development
• Pay 2.50- 5.00 an acre
• Then they can do whatever they want with it

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General Mining Law of 1872

• Mining companies (F D) remove 2-3 BILLION in
  resources each year from land they got this way!
• About 20 of companies with mining rights on US
  public lands are FOREIGN!

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General Mining Law of 1872

• Modified in 1992 to require companies to post
  bonds to cover the full amount of a clean up in
  case the company goes bankrupt
• Clean up would cost taxpayers 33-72 Billion
• Lobbyists are trying to weaken these laws

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Environmental Concerns

• Dont sell the land
• Lease it for up to 20 years
• Pay royalties on whatever they remove
• Stricter clean up requirements

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Nonrenewable Mineral Resources

• Concentration of naturally occurring material in
  or on the crust that can be extracted processed
  at a reasonable cost
• Take a long time to produce
• ______________________________________
• Energy

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Nonrenewable Mineral Resources

• ________________________________ we know where
  they are and how much there is
• _________________________ resources we can
  extract at a reasonable price
• ________________________________ potential
  supplies, dont know for sure it is there or how
  much there is
• Other- discovered or undiscovered but not a
  reserve

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How do we find resources?

• Aerial photos and satellite images
• Detect radiation from radioactive deposits
  (Uranium)
• Magnetometer to detect changes in magnetic field
  (Iron ore)
• Gravimeter to detect changes in gravity caused by
  different densities of rock

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Underground Methods

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• _______________a rock containing enough metallic
  minerals to be mined profitably
• Mineral unwanted gangue
• ________________gangue that has been separated
  from the desired mineral
• ________________identified resources from which
  nonrenewable minerals can be extracted profitably

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Ore Deposits

• The most common way that ore deposits form is
  through hydrothermal processes
• especially at divergent boundaries ? superheated
  seawater dissolves metals
• hydrothermal vents support marine ecosystems
  based on chemosynthesis
• sedimentary sorting based on density (panning for
  gold)
• evaporite mineral deposits ? water evaporates
  leaving minerals
• residual deposits ? left when soluble minerals
  are washed away thereby concentrating insoluble
  minerals nonrenewable

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Removing Mineral Resources

• Overburden of soil and rock is removed and
  discarded as spoil
• Types of Surface Mining
• Open-pit
• Dredging of underwater mineral deposits
• Area strip mining
• Contour strip mining
• Subsurface mining
• disturbs less than 1/10 as much land as surface
  mining
• more hazardous, more expensive, less productive

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Open Pit Mine
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Dredging
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Area Strip Mining
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Contour Strip Mining
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Subsurface Underground Coal Mine
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Environmental Impacts of Mining

• _______________________ are the waste materials
  left over after removing the minerals from ore.
• Tailings are sometimes reprocessed.
• Common contents of tailings
• Arsenic
• Barite
• Calcite
• Cyanide
• Fluorite
• Mercury
• Pyrite
• Quartz

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Environmental Impacts of Mining

• Disruption of land
• Subsidence of land
• Wind or water erosion of mineral waste
• Acid mine drainage ? sulfuric acid released
• Emission of toxic chemicals into the air
• Leakage of toxic wastes into waterways
• Smelting ? separates the metals from other
  substances ? made into products which are used
  and then recycled or discarded
• this process emits huge quantities of air
  pollutants (without effective pollution controls)
• water pollution
• produces hazardous wastes

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Restoration Reclamation

• Reclamation make land suitable for another
  purpose (agriculture, recreation, etc)
• Restoration restore native habitat
• Regrading the land to original topography
• Replacing topsoil
• Planting native vegetation

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Steps
Environmental Effects
Disturbed land mining accidents health hazards
mine waste dumping oil spills and blowouts
noise ugliness heat
Mining
exploration, extraction
Processing
Solid wastes radioactive material air, water,
and soil pollution noise safety and
health hazards ugliness heat
transportation, purification, manufacturing
Noise ugliness thermal water pollution pollution
of air, water, and soil solid and radioactive
wastes safety and health hazards heat
Use
transportation or transmission to individual
user, eventual use, and discarding
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Subsurface Mine Opening
Surface Mine
Runoff of sediment
Acid drainage from reaction of mineral or ore
with water
Spoil banks
Leaching may carry acids into soil
and ground water supplies
Percolation to groundwater
Leaching of toxic metals and other compounds from
mine spoil
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Smelting
Separation of ore from gangue
Melting metal
Conversion to product
Metal ore
Recycling
Discarding of product
Surface mining
Fig. 14.8, p. 327
Scattered in environment
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Supplies of Mineral Resources

• Economic depletion
• Mining lower grade ores, mining ocean floor.
  seawater extraction ? expensive!
• Mining is subsidized in US ? government tax
  deductions, depletion allowances, Mining Law of
  1872
• Sagebrush Rebellion in the 80s ? miners,
  ranchers, etc. pushed for opening up federal
  public lands for use
• 72 of US Public lands are in Alaska 22 are in
  western states
• Using alternative products ? ceramics, plastics

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Mine, use, throw away no new discoveries rising
prices
A
Recycle increase reserves by improved
mining technology, higher prices, and new
discoveries
B
Production
Recycle, reuse, reduce consumption
increase reserves by improved mining
technology, higher prices, and new discoveries
C
Present
Depletion time A
Depletion time B
Depletion time C
Time