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Geology and Nonrenewable Minerals
Chapter 9
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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?
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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
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General Mining Law of 1872 Fig. 12-1, p. 269
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Internal Geologic Processes
What is geology? Earth’s internal structure Core Mantle Crusts (continental and oceanic) Plate tectonics
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General Structure of the Earth
Oceanic crust Continental crust Atmosphere Vegetation and animals Biosphere Lithosphere Soil Upper mantle 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
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Earth’s Crust and Upper Mantle
Abyssal hills Folded mountain belt Abyssal floor Oceanic ridge Abyssal floor Trench 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
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Plate Tectonics Tectonic plates Lithosphere
Plate tectonics and biological evolution
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Plate Tectonics Fig. 12-3, p. 272 Spreading center Oceanic tectonic
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 Mantle convection cell Hot material rising through the mantle Two plates move towards each other. One is subducted back into the mantle on falling convection current. Mantle Hot outer core Inner core Inner core Fig. 12-3, p. 272
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Earth’s 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
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Types of Plate Boundaries
Divergent Convergent Transform Fig. 12-5, p. 274
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Types of Plate Boundaries
Lithosphere Asthenosphere Oceanic ridge at a divergent plate boundary Fig. 12-5a, p. 274
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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
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Types of Plate Boundaries
Fracture zone Transform fault Lithosphere Asthenosphere Transform fault connecting two divergent plate boundaries Fig. 12-5c, p. 274
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External Earth Processes
Erosion Physical (mechanical) weathering: frost wedging Chemical weathering Biological weathering
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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
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The Rock Cycle Fig. 12-6, p. 275 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
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Mineral Resources Generally nonrenewable
Metallic, nonmetallic, and energy resources Ores
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Categories of Mineral Resources
Identified Undiscovered Reserves Other Fig. 12-7, p. 276
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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
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Finding Mineral Resources
Aerial and satellite images Radiation detectors Magnetometers Gravimeters Seismic surveys Chemical analyses
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Extracting Mineral Deposits
Surface mining Subsurface mining Overburden Spoils
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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
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Open-pit Mine Fig. 12-8, p. 277
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Spoil from an Unrestored Area Strip Mine
Fig. 12-9, p. 277
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Contour Strip Mining Undisturbed Land Overburden Highwall Coal seam
Pit Bench Coal seam Spoil Banks Fig , p. 277
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Mountaintop Mining Fig , p. 278
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Environmental Effects of Using Mineral Resources
Disrupting the land surface Subsidence Toxic mining waste Acid mine drainage Air pollution Toxic holding ponds
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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 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, purifi- cation, manufacturing Use Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat transportation or trans- mission to individual user, eventual use, and discarding Fig , p. 279
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Processing of Mineral Resources
Ore mineral Gangue Tailings Smelting Products Disposal or recycling
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Typical Life Cycle of a Metal Resource
Surface mining Metal ore Separation of ore from gangue Smelting Melting metal Conversion to product Discarding of product (Scattered in environ-ment) Reuse Recycling Fig , p. 279
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Environmental Limits to Resource Extraction
Environmental damage: a major mining problem Ore grade Including environmental costs in products How Would You Vote exercise
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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
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Depletion Curves for a Nonrenewable Resource
Mine, use, throw away; no new discoveries; rising prices 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 , p. 280 Time
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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
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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
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Nanotechnology Revolution
Buckyballs Molecular economy Possible achievements of nanotechnology Possible environmental and health threats Likely need for guidelines and regulations
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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
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Hydrothermal Ore Deposits on the Ocean Floor
White smoker Black smoker Sulfide deposit Magma Tube worms White crab White clam Fig , p. 283
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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
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