Geology and Nonrenewable Minerals

1
Geology and Nonrenewable Minerals

• Chapter 12

2
Key Concepts

• Major geologic processes
• Rocks and the rock cycle
• Finding and extracting mineral resources
• Environmental effects of mining
• Enough nonrenewable resources for the future?

3
General Mining Law of 1872

• Original purpose of the law
• Impact on US public lands
• Benefits to mining companies
• Costs to the public
• Environmental issues
• Laws in other countries
• How Would You Vote exercise

Fig. 12-1, p. 269
4
General Mining Law of 1872
Fig. 12-1, p. 269
5
Internal Geologic Processes

• What is geology?
• Earths internal structure
• Core
• Mantle
• Crusts (continental and oceanic)
• Plate tectonics

6
General Structure of the Earth
Oceanic crust
Continental crust
Atmosphere
Biosphere
Vegetation and animals
Lithosphere
Upper mantle
Soil
Crust
Asthenosphere
Rock
Lower mantle
Core
Mantle
Crust (soil and rock)
Biosphere (living and dead organisms)
Hydrosphere (water)
Lithosphere (crust, top of upper mantle)
Atmosphere (air)
Fig. 3-5, p. 38
7
Earths Crust and Upper Mantle
Abyssal hills
Folded mountain belt
Abyssal floor
Oceanic ridge
Trench
Abyssal floor
Craton
Volcanoes
Continental rise
Oceanic crust (lithosphere)
Continental slope
Abyssal plain
Continental shelf
Abyssal plain
Continental crust (lithosphere)
Mantle (lithosphere)
Mantle (lithosphere)
Mantle (asthenosphere)
Fig. 12-2, p. 271
8
Plate Tectonics

• Tectonic plates
• Lithosphere
• Plate tectonics and biological evolution

9
Plate Tectonics
Spreading center
Oceanic tectonic plate
Oceanic tectonic plate
Ocean trench
Collision between two continents
Plate movement
Plate movement
Tectonic plate
Oceanic crust
Oceanic crust
Subduction zone
Continental crust
Continental crust
Material cools as it reaches the outer mantle
Cold dense material falls back through mantle
Hot material rising through the mantle
Mantle convection cell
Mantle
Two plates move towards each other. One is
subducted back into the mantle on falling
convection current.
Hot outer core
Inner core
Inner core
Fig. 12-3, p. 272
10
Earths Major Tectonic Plates
EURASIAN PLATE
ANATOLIAN PLATE
NORTH AMERICAN PLATE
JUAN DE FUCA PLATE
CHINA SUBPLATE
CARIBBEAN PLATE
PHILIPPINE PLATE
ARABIAN PLATE
AFRICAN PLATE
PACIFIC PLATE
SOUTH AMERICAN PLATE
NAZCA PLATE
INDIAN-AUSTRLIAN PLATE
SOMALIAN SUBPLATE
ANTARCTIC PLATE
Convergent plate boundaries
Divergent boundaries
Transform faults
Fig. 12-4, p. 273
11
Types of Plate Boundaries

• Divergent
• Convergent
• Transform

Fig. 12-5, p. 274
12
Types of Plate Boundaries
Lithosphere
Asthenosphere
Oceanic ridge at a divergent plate boundary
Fig. 12-5a, p. 274
13
Types of Plate Boundaries
Volcanic island arc
Trench
Lithosphere
Rising magma
Asthenosphere
Subduction zone
Trench and volcanic island arc at a convergent
plate boundary
Fig. 12-5b, p. 274
14
Types of Plate Boundaries
Fracture zone
Transform fault
Lithosphere
Asthenosphere
Transform fault connecting two divergent plate
boundaries
Fig. 12-5c, p. 274
15
External Earth Processes

• Erosion
• Physical (mechanical) weathering frost wedging
• Chemical weathering
• Biological weathering

16
Minerals and Rocks

• Minerals (as examples quartz and diamonds)
• Rocks
• Rock types
• Igneous (granite and basalt)
• Sedimentary (sandstone and limestone)
• Metamorphic (marble and slate)
• Rock cycle

17
The Rock Cycle
Erosion
Transportation
Weathering
Deposition
Igneous Rock Granite,pumice, basalt
Sedimentary Rock sandstone, limestone
Heat, pressure
Cooling
Magma (molten rock)
Heat, pressure, stress
Melting
Metamorphic Rock Slate, marble, gneiss quartzite
Fig. 12-6, p. 275
18
Mineral Resources

• Generally nonrenewable
• Metallic, nonmetallic, and energy resources
• Ores

19
Categories of Mineral Resources

• Identified
• Undiscovered
• Reserves
• Other

Fig. 12-7, p. 276
20
Categories of Mineral Resources
Undiscovered
Identified
Reserves
Economical
Other resources
Decreasing cost of extraction
Not economical
Decreasing certainty
Known
Existence
Fig. 12-7, p. 276
21
Finding Mineral Resources

• Aerial and satellite images
• Radiation detectors
• Magnetometers
• Gravimeters
• Seismic surveys
• Chemical analyses

22
Extracting Mineral Deposits

• Surface mining
• Subsurface mining
• Overburden
• Spoils

23
Mining Methods

• Open-pit (surface mining)
• Area strip mining (surface)
• Contour strip mining (surface)
• Mountaintop removal (surface)
• Subsurface mining
• Hazards and environmental tradeoffs of subsurface
  mining

24
Open-pit Mine
Fig. 12-8, p. 277
25
Spoil from an Unrestored Area Strip Mine
Fig. 12-9, p. 277
26
Contour Strip Mining
Undisturbed Land
Overburden
Highwall
Coal seam
Overburden
Pit
Bench
Coal seam
Spoil Banks
Fig. 12-10, p. 277
27
Mountaintop Mining
Fig. 12-11, p. 278
28
Environmental Effects of Using Mineral Resources

• Disrupting the land surface
• Subsidence
• Toxic mining waste
• Acid mine drainage
• Air pollution
• Toxic holding ponds

29
Environmental Effects of Mineral Use
Natural Capital Degredation
Extracting, Processing, and Using Nonrenewable
Mineral and Energy Resources
Steps
Environmental Effects
Disturbed land mining accidents health hazards
mine waste dumpingoil 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, purifi-cation, manufacturing
Noise ugliness thermal water pollution
pollution of air, water, and soil solid and
radioactive wastes safety and health hazards
heat
Use
transportation or trans-mission to individual
user, eventual use, and discarding
Fig. 12-12, p. 279
30
Processing of Mineral Resources

• Ore mineral
• Gangue
• Tailings
• Smelting
• Products
• Disposal or recycling

31
Typical Life Cycle of a Metal Resource
Surface mining
Metal ore
Separation of ore from gangue
Discarding of product(Scattered in environ-ment)
Conversion to product
Melting metal
Smelting
Reuse
Recycling
Fig. 12-13, p. 279
32
Environmental Limits to Resource Extraction

• Environmental damage a major mining problem
• Ore grade
• Including environmental costs in products
• How Would You Vote exercise

33
Supplies of Mineral Resources

• Available supply and use
• Economic depletion
• Five choices after depletion
• Recycle or reuse
• Waste less
• Use less
• Find a substitute
• Do without
• Depletion time
• Economics
• Finding alternatives

34
Depletion Curves for a Nonrenewable Resource
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
Fig. 12-14, p. 280
Time
35
Economics and Supplies of Nonrenewable Resources

• Roll of economics in mining
• Standard economic theory
• Limited free market in developed countries
• Government subsidies of mining
• 1872 US General Mining Law
• Economic problems of developing new mines

36
Mining Lower-grade Ores

• New extraction technologies are needed
• Factors that limit mining lower-grade ores
• Costs
• Supplies of freshwater
• Environmental impacts
• Biomining microorganisms and in-situ mining

37
Nanotechnology Revolution

• Nanotechnology
• Buckyballs
• Molecular economy
• Possible achievements of nanotechnology
• Possible environmental and health threats
• Likely need for guidelines and regulations

38
Ocean Mining

• Ore deposits in the ocean
• Minerals from seawater
• Minerals in ocean sediments
• Hydrothermal deposits
• Manganese-rich nodules
• Mining issues in international waters
• Environmental issues

39
Hydrothermal Ore Deposits on the Ocean Floor
White smoker
Black smoker
Sulfide deposit
Magma
Tube worms
White crab
White clam
Fig. 12-15, p. 283
40
Finding Substitutes for Scarce Mineral Resources

• Materials revolution
• Ceramic substitutes
• High-strength plastics and composites
• Finding some substitutes may be impossible
• Some substitutes are inferior