Geology and Nonrenewable Mineral Resources Chapter 15 Geology and Nonrenewable Mineral Resources

Chapter Overview Questions What major geologic processes occur within the earth and on its surface? What are nonrenewable mineral resources and where are they found? What are rocks, and how are they recycled by the rock cycle? How do we find and extract mineral resources from the earth’s crust, and what harmful environmental effects result from removing and using these minerals?

Chapter Overview Questions (cont’d) Will there be enough nonrenewable mineral resources for future generations? Can we find substitutes for scarce nonrenewable mineral resources? How can we shift to more sustainable use of nonrenewable mineral resources?

Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. InfoTrac: Residents discuss towns' deaths. Daily Oklahoman (Oklahoma City, OK) August 2, 2006. InfoTrac: All that glitters: the demand for gold is soaring. Jane Perlez, Kirk Johnson. New York Times, May 8, 2006 v138 i14 p12(6) . InfoTrac: In Old Mining Town, New Charges Over Asbestos. Kirk Johnson. The New York Times, April 22, 2006 pA1(L). Science Daily: Putting Coal Ash Back Into Mines A Viable Option For Disposal, But Risks Must Be Addressed National Park Service: Mining Operations Management Arizona Mining Association: From the Ground Up: Mining/Mineral Resource Development

Core Case Study: The Nanotechnology Revolution Nanotechnology uses science and engineering to create materials out of atoms and molecules at the scale of less than 100 nanometers. Little environmental harm: Does not use renewable resources. Potential biological concerns. Can move through cell membranes: Figure 15-1

GEOLOGIC PROCESSES The earth is made up of a core, mantle, and crust and is constantly changing as a result of processes taking place on and below its surface. The earth’s interior consists of: Core: innermost zone with solid inner core and molten outer core that is extremely hot. Mantle: solid rock with a rigid outer part (asthenosphere) that is melted pliable rock. Crust: Outermost zone which underlies the continents.

GEOLOGIC PROCESSES Major features of the earth’s crust and upper mantle. Figure 15-2

Oceanic crust (lithosphere) Abyssal plain Continental slope Folded mountain belt Volcanoes Abyssal plain Abyssal floor Oceanic ridge Abyssal floor Abyssal hills Trench Craton Oceanic crust (lithosphere) Abyssal plain Continental slope Continental shelf Continental rise Mantle (lithosphere) Continental crust (lithosphere) Mantle (lithosphere) Figure 15.2 Natural capital: major features of the earth’s crust and upper mantle. The lithosphere, composed of the crust and outermost mantle, is rigid and brittle. The asthenosphere, a zone in the mantle, can be deformed by heat and pressure. Mantle (asthenosphere) Fig. 15-2, p. 336

Tectonic plate Inner core Spreading center Collision between two continents Oceanic tectonic plate Ocean trench Oceanic tectonic plate 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 Figure 15.3 Natural capital: the earth’s crust is made up of a mosaic of huge rigid plates, called tectonic plates, which move around in response to forces in the mantle. Mantle Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Hot outer core Inner core Fig. 15-3, p. 337

GEOLOGIC PROCESSES Huge volumes of heated and molten rack moving around the earth’s interior form massive solid plates that move extremely slowly across the earth’s surface. Tectonic plates: huge rigid plates that are moved with convection cells or currents by floating on magma or molten rock.

The Earth’s Major Tectonic Plates Figure 15-4

The Earth’s Major Tectonic Plates The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart at divergent plate boundaries and slide past at transform plate boundaries. Figure 15-4

Figure 15.4 Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on? Fig. 15-4, p. 338

INDIA-AUSTRALIAN PLATE EURASIAN PLATE NORTH AMERICAN PLATE ANATOLIAN PLATE JUAN DE FUCA PLATE CARIBBEAN PLATE CHINA SUBPLATE ARABIAN PLATE AFRICAN PLATE PHILIPPINE PLATE PACIFIC PLATE SOUTH AMERICAN PLATE NAZCA PLATE INDIA-AUSTRALIAN PLATE SOMALIAN SUBPLATE Figure 15.4 Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on? ANTARCTIC PLATE Divergent plate boundaries Convergent plate boundaries Transform faults Fig. 15-4a, p. 338

Transform fault Rising magma Trench Volcanic island arc Craton Transform fault Lithosphere Rising magma Subduction zone Lithosphere Lithosphere Asthenosphere Asthenosphere Asthenosphere Figure 15.4 Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on? Divergent plate boundaries Convergent plate boundaries Transform faults Fig. 15-4b, p. 338

GEOLOGIC PROCESSES The San Andreas Fault is an example of a transform fault. Figure 15-5

Wearing Down and Building Up the Earth’s Surface Weathering is an external process that wears the earth’s surface down. Figure 15-6

Parent material (rock) Biological weathering (tree roots and lichens) Chemical weathering (water, acids, and gases) Physical weathering (wind, rain, thermal expansion and contraction, water freezing) Figure 15.6 Natural capital: physical, chemical, and biological processes can weather or convert rock into smaller fragments and particles. It is the first step in soil formation. Particles of parent material Fig. 15-6, p. 340

MINERALS, ROCKS, AND THE ROCK CYCLE The earth’s crust consists of solid inorganic elements and compounds called minerals that can sometimes be used as resources. Mineral resource: is a concentration of naturally occurring material in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost.

General Classification of Nonrenewable Mineral Resources The U.S. Geological Survey classifies mineral resources into four major categories: Identified: known location, quantity, and quality or existence known based on direct evidence and measurements. Undiscovered: potential supplies that are assumed to exist. Reserves: identified resources that can be extracted profitably. Other: undiscovered or identified resources not classified as reserves

General Classification of Nonrenewable Mineral Resources Examples are fossil fuels (coal, oil), metallic minerals (copper, iron), and nonmetallic minerals (sand, gravel). Figure 15-7

Decreasing cost of extraction Undiscovered Identified Economical Reserves Other resources Decreasing cost of extraction Not economical Figure 15.7 Natural capital: general classification of nonrenewable mineral resources. (The area shown for each class does not represent its relative abundance.) Hypothetically, other resources could become reserves because of rising mineral prices or improved mineral location and extraction technology. In practice, geologists expect only a fraction of these resources to become reserves. QUESTION: How might this classification scheme change if a full-blown nanotechnology revolution (p. 335) takes place over the next two decades? Decreasing certainty Known Existence Fig. 15-7, p. 341

GEOLOGIC PROCESSES Deposits of nonrenewable mineral resources in the earth’s crust vary in their abundance and distribution. A very slow chemical cycle recycles three types of rock found in the earth’s crust: Sedimentary rock (sandstone, limestone). Metamorphic rock (slate, marble, quartzite). Igneous rock (granite, pumice, basalt).

Rock Cycle Figure 15-8

Erosion Transportation Heat, pressure, stress Magma (molten rock) Weathering Deposition Igneous rock Granite, pumice, basalt Sedimentary rock Sandstone, limestone Heat, pressure Cooling Heat, pressure, stress Magma (molten rock) Figure 15.8 Natural capital: the rock cycle is the slowest of the earth’s cyclic processes. The earth’s materials are recycled over millions of years by three processes: melting, erosion, and metamorphism, which produce igneous, sedimentary, and metamorphic rocks. Rock from any of these classes can be converted to rock of either of the other two classes, or can be recycled within its own class. QUESTION: List three ways that the rock cycle benefits your lifestyle. Melting Metamorphic rock Slate, marble, gneiss, quartzite Fig. 15-8, p. 343

ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES The extraction, processing, and use of mineral resources has a large environmental impact. Figure 15-9

Fig. 15-9, p. 344 Surface mining Metal ore Separation of ore from gangue Smelting Melting metal Conversion to product Discarding of product (scattered in environment) Figure 15.9 Natural capital degradation: life cycle of a metal resource. Each step in this process uses large amounts of energy and produces air and water pollution and huge amounts of crushed rock and other forms of solid waste. The lower the grade of ore, the greater these environmental impacts. Recycling Fig. 15-9, p. 344

Natural Capital Degradation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Environmental effects Mining Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat Exploration, extraction Processing Transportation, purification, manufacturing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Use Figure 15.10 Natural capital degradation: some harmful environmental effects of extracting, processing, and using nonrenewable mineral and energy resources. The energy required to carry out each step causes additional pollution and environmental degradation. Transportation or transmission to individual user, eventual use, and discarding Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat Fig. 15-10, p. 344

ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES Minerals are removed through a variety of methods that vary widely in their costs, safety factors, and levels of environmental harm. A variety of methods are used based on mineral depth. Surface mining: shallow deposits are removed. Subsurface mining: deep deposits are removed.

Open-pit Mining Machines dig holes and remove ores, sand, gravel, and stone. Toxic groundwater can accumulate at the bottom. Figure 15-11

Area Strip Mining Earth movers strips away overburden, and giant shovels removes mineral deposit. Often leaves highly erodible hills of rubble called spoil banks. Figure 15-12

Contour Strip Mining Used on hilly or mountainous terrain. Unless the land is restored, a wall of dirt is left in front of a highly erodible bank called a highwall. Figure 15-13

Undisturbed land Overburden Highwall Coal seam Overburden Pit Bench Figure 15.13 Natural capital degradation: contour strip mining of coal used in hilly or mountainous terrain. Spoil banks Fig. 15-13, p. 346

Mountaintop Removal Machinery removes the tops of mountains to expose coal. The resulting waste rock and dirt are dumped into the streams and valleys below. Figure 15-14

Mining Impacts Metal ores are smelted or treated with (potentially toxic) chemicals to extract the desired metal. Figure 15-15

SUPPLIES OF MINERAL RESOURCES The future supply of a resource depends on its affordable supply and how rapidly that supply is used. A rising price for a scarce mineral resource can increase supplies and encourage more efficient use.

SUPPLIES OF MINERAL RESOURCES Depletion curves for a renewable resource using three sets of assumptions. Dashed vertical lines represent times when 80% depletion occurs. Figure 15-16

Depletion time A Depletion time B Depletion time C 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 Figure 15.16 Natural capital depletion: depletion curves for a nonrenewable resource (such as aluminum or copper) using three sets of assumptions. Dashed vertical lines represent times when 80% depletion occurs. Present Depletion time A Depletion time B Depletion time C Time Fig. 15-16, p. 348

SUPPLIES OF MINERAL RESOURCES New technologies can increase the mining of low-grade ores at affordable prices, but harmful environmental effects can limit this approach. Most minerals in seawater and on the deep ocean floor cost too much to extract, and there are squabbles over who owns them.

Getting More Minerals from the Ocean Hydrothermal deposits form when mineral-rich superheated water shoots out of vents in solidified magma on the ocean floor. Figure 15-17

Black smoker White smoker Sulfide deposits Magma White clam White crab Figure 15.17 Natural capital: hydrothermal deposits form when mineral-rich superheated water shoots out of vents in solidified magma on the ocean floor. After mixing with cold seawater, black particles of metal compounds precipitate out and build up as chimneylike mineral deposits around the vents. A variety of organisms, supported by bacteria that produce food by chemosynthesis, exist in the dark ocean around these black smokers. White clam White crab Tube worms Fig. 15-17, p. 350

USING MINERAL RESOURCES MORE SUSTAINABLY Scientists and engineers are developing new types of materials as substitutes for many metals. Recycling valuable and scarce metals saves money and has a lower environmental impact then mining and extracting them from their ores.

Sustainable Use of Nonrenewable Minerals Solutions Sustainable Use of Nonrenewable Minerals • Do not waste mineral resources. • Recycle and reuse 60–80% of mineral resources. • Include the harmful environmental costs of mining and processing minerals in the prices of items (full-cost pricing). • Reduce subsidies for mining mineral resources. • Increase subsidies for recycling, reuse, and finding less environmentally harmful substitutes. • Redesign manufacturing processes to use less mineral resources and to produce less pollution and waste. Figure 15.18 Solutions: ways to achieve more sustainable use of nonrenewable mineral resources. QUESTION: Which two of the solutions do you think are the most important? • Have the mineral-based wastes of one manufacturing process become the raw materials for other processes. • Sell services instead of things. • Slow population growth. Fig. 15-18, p. 351

Case Study: The Ecoindustrial Revolution Growing signs point to an ecoindustrial revolution taking place over the next 50 years. The goal is to redesign industrial manufacturing processes to mimic how nature deals with wastes. Industries can interact in complex resource exchange webs in which wastes from manufacturer become raw materials for another.

Case Study: The Ecoindustrial Revolution Figure 15-19

Sulfuric acid producer Sludge Pharmaceutical plant Local farmers Sludge Greenhouses Waste heat Waste heat Waste heat Fish farming Waste heat Surplus natural gas Electric power plant Fly ash Oil refinery Surplus sulfur Waste calcium sulfate Figure 15.19 Solutions: the industrial ecosystem in Kalundborg, Denmark, reduces waste production by mimicking a natural food web. The wastes of one business become the raw materials for another. QUESTION: Is there an industrial ecosystem near where you live or go to school? If not, why not? Waste heat Cement manufacturer Surplus natural gas Sulfuric acid producer Wallboard factory Area homes Fig. 15-19, p. 352