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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.

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GEOLOGIC PROCESSES

Major features of the earth’s crust and upper mantle.

Figure 15-2

Fig. 15-2, p. 336

Volcanoes

Folded mountain belt

Abyssal floor

Oceanic ridge

Abyssal floor TrenchAbyssal hills

Craton

Abyssal plain

Oceanic crust (lithosphere)

Continental shelf

Continental slope

Continental rise

Continental crust (lithosphere)

Mantle (lithosphere)

Fig. 15-3, p. 337

Spreading center Ocean

trench

Subduction zone

Oceanic crust

Continental crust

Continental crust

Material cools as it reaches

the outer mantle

Cold dense material falls back through

mantleHot

material rising

through the

mantle

Mantle convection

cell

Two plates move towards each other. One is subducted back into the mantle on a falling convection current.

Mantle

Hot outer core Inner

core

Collision between two continents

Oceanic crust

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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

PLAYANIMATION

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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

Fig. 15-4a, p. 338

EURASIAN PLATENORTH AMERICAN PLATE

ANATOLIAN PLATE

JUAN DE FUCA PLATE

CHINA SUBPLATE

CARIBBEAN PLATE

PHILIPPINE PLATE

ARABIAN PLATEAFRICAN

PLATEPACIFIC PLATE SOUTH

AMERICAN PLATENAZCA

PLATEINDIA-

AUSTRALIAN PLATE

SOMALIAN SUBPLATE

ANTARCTIC PLATE

Divergent plate boundaries

Convergent plate boundaries

Transform faults

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Fig. 15-4b, p. 338

Trench Volcanic island arc Craton

Transform fault

Lithosphere

Lithosphere Lithosphere

Asthenosphere Asthenosphere Asthenosphere

Divergent plate boundaries Convergent plate boundaries Transform faults

Rising magma

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

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Fig. 15-6, p. 340

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

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

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General Classification of Nonrenewable Mineral Resources

Examples are fossil fuels (coal, oil), metallic minerals (copper, iron), and nonmetallic minerals (sand, gravel).

Figure 15-7

Fig. 15-7, p. 341

Undiscovered Identified

Reserves

Eco

no

mic

al

Other resources

Dec

reas

ing

co

st o

f ex

trac

tio

n

No

t ec

on

om

ical

Decreasing certainty Known

Existence

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).

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Rock Cycle

Figure 15-8

Fig. 15-8, p. 343

Erosion

Transportation

Weathering

Deposition

Igneous rock Granite, pumice, basalt

Sedimentary rock Sandstone, limestone

Heat, pressure

Cooling

Heat, pressure, stress

Magma (molten rock)

Melting

Metamorphic rock Slate, marble, gneiss, quartzite

ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES

The extraction, processing, and use of mineral resources has a large environmental impact.

Figure 15-9

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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)

Recycling

Fig. 15-10, 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

Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat

Transportation, purification, manufacturing

Use

Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat

Transportation or transmission to individual user, eventual use, and discarding

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.

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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

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Fig. 15-13, p. 346

Undisturbed land

Overburden

PitBench

Spoil banks

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

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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

Fig. 15-16, p. 348

A Mine, use, throw away; no new discoveries; rising prices

Recycle; increase reserves by improved mining technology, higher prices, and new discoveriesB

Pro

du

ctio

n

Recycle, reuse, reduce consumption; increase reserves by improved mining technology, higher prices, and new discoveriesC

Present Depletion time A

Depletion time B

Depletion time C

Time

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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

Fig. 15-17, p. 350

Black smoker

White smoker

Sulfide deposits

Magma

White clamWhite crab Tube

worms

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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.

Fig. 15-18, p. 351

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.

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.

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Case Study: The Ecoindustrial Revolution

Figure 15-19

Fig. 15-19, p. 352

Sludge

Pharmaceutical plant Local farmers

SludgeGreenhouses Waste

heat

Waste heat Fish farming

Oil refinery Surplus natural gas

Electric power plant

Surplus sulfur

Waste calcium sulfate

Cement manufacturer

Sulfuric acid producer

Wallboard factory Area homes