Chapter 15. Geology and Nonrenewable Mineral Resources 1/17/2016. Core Case Study: The Nanotechnology Revolution GEOLOGIC PROCESSES

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1 Chapter 15 Geology and Nonrenewable Mineral Resources 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. 1

2 GEOLOGIC PROCESSES Major features of the earth s crust and upper mantle. Figure 15-2 Abyssal hills Abyssal Oceanic floor ridge Abyssal floor Trench Volcanoes Folded mountain belt Abyssal plain Craton Oceanic crust (lithosphere) Continental shelf Continental slope Continental rise Continental crust (lithosphere) Mantle (lithosphere) Fig. 15-2, p. 336 Collision between two continents Spreading center Ocean trench Subduction zone Continental crust Mantle convection cell Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Oceanic crust Material cools Cold dense as it reaches material falls the outer back through mantle mantle Hot material rising through the mantle Hot outer core Inner core Oceanic crust Continental crust Mantle Fig. 15-3, p

3 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 Animation: Geological Forces PLAY ANIMATION 3

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 Fig. 15-4, p. 338 JUAN DE FUCA PACIFIC NORTH AMERICAN CARIBBEAN SOUTH AMERICAN NAZCA EURASIAN ANATOLIAN CHINA SUB ARABIAN AFRICAN SOMALIAN SUB INDIA- AUSTRALIAN PHILIPPINE ANTARCTIC Divergent plate boundaries Convergent plate boundaries Transform faults Fig. 15-4a, p

5 Trench Volcanic island arc Craton Transform fault Lithosphere Lithosphere Rising magma Lithosphere Asthenosphere Asthenosphere Asthenosphere 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

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) 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 6

7 General Classification of Nonrenewable Mineral Resources Examples are fossil fuels (coal, oil), metallic minerals (copper, iron), and nonmetallic minerals (sand, gravel). Figure 15-7 Undiscovered Identified Decreasing cost of extraction Other resources Reserves Economical Not economical 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). 7

8 Rock Cycle Figure 15-8 Transportation Erosion Weathering Deposition Sedimentary rock Sandstone, limestone Heat, pressure Igneous rock Granite, pumice, basalt Heat, pressure, stress Magma (molten rock) Cooling 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

9 Surface mining Metal ore Separation of ore from gangue Smelting Recycling Melting metal Conversion to product Discarding of product (scattered in environment) Fig. 15-9, p. 344 Natural Capital Degradation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Mining Exploration, extraction Processing Transportation, purification, manufacturing Use Transportation or transmission to individual user, eventual use, and discarding Environmental effects Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat Fig , 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. 9

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

11 Undisturbed land Overburden Pit Bench Spoil banks Fig , 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 Mining Impacts Metal ores are smelted or treated with (potentially toxic) chemicals to extract the desired metal. Figure

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

13 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 Black smoker White smoker Sulfide deposits Magma White crab White clam Tube worms Fig , p

14 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. 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. 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 , 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. 14

15 Case Study: The Ecoindustrial Revolution Figure Sludge Greenhouses Pharmaceutical plant Waste heat Local farmers Sludge Oil refinery Surplus sulfur Waste heat Surplus natural gas Electric power plant Waste calcium sulfate Fish farming Cement manufacturer Sulfuric acid producer Wallboard factory Area homes Fig , p