Geology and Nonrenewable Mineral Resources

1
Chapter 15

• Geology and Nonrenewable Mineral Resources

2
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 earths 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.

3
GEOLOGIC PROCESSES

• Major features of the earths crust and upper
  mantle.

Figure 15-2
4

Spreading center
Ocean trench
Collision between two continents
Oceanic tectonic plate
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
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
5
GEOLOGIC PROCESSES

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

6
The Earths Major Tectonic Plates
Figure 15-4
7
The Earths 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
8

Fig. 15-4, p. 338
9
GEOLOGIC PROCESSES

• The San Andreas Fault is an example of a
  transform fault.

Figure 15-5
10
Wearing Down and Building Up the Earths Surface

• Weathering is an external process that wears the
  earths surface down.

Figure 15-6
11
MINERALS, ROCKS, AND THE ROCK CYCLE

• The earths 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 earths crust
  that can be extracted and processed into useful
  materials at an affordable cost.

12
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

13
General Classification of Nonrenewable Mineral
Resources

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

Figure 15-7
14
GEOLOGIC PROCESSES

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

15

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
Fig. 15-8, p. 343
16
ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES

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

Figure 15-9
17

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
Fig. 15-10, p. 344
18
ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES

• A variety of methods are used based on mineral
  depth.
• Surface mining shallow deposits are removed.
• Remove overburden
• Discard as waste material (spoils)
• Examples
• Open-pit mining, area strip mining, contour strip
  mining, mountain-top removal
• Subsurface mining deep deposits are removed.

19
Open-pit Mining

• Machines dig holes and remove ores, sand, gravel,
  and stone.
• Toxic groundwater can accumulate at the bottom.

Figure 15-11
20
Area Strip Mining

• Earth movers strips away overburden, and giant
  shovels removes mineral deposit.
• Often leaves highly erodible hills of rubble
  called spoil banks.
• Succession slow after mining no topsoil
• Desertification in arid areas

Figure 15-12
21
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
22
Mountaintop Removal

• Machinery removes the tops of mountains to expose
  coal.
• Resulting waste rock and dirt are dumped into the
  streams and valleys below.
• Causes flood hazards
• Leaches toxic metals into waterways
• Increasing in WV and KY

Figure 15-14
23
Case Study Kayford Mt, WV
before
after
Larry Gibson on the issue
A positive view
24
Mining Impacts

• Scarring and disruption of the land surface
• Subsidence
• Toxin laced mining wastes
• Air pollution
• Acid deposition from smelting gases

Figure 15-15
25
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.

• Never completely run out
• Economic depletion costs more to find, extract,
  transport, and process the remaining deposit than
  it is worth.
• Options
• Recycle/reuse
• Waste less
• Use less
• Find a substitute
• Do without

26
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
27
MINING TRENDS

• Mining no longer a free market
• Subsidized for depletion
• Consumer pays via taxes
• New technologies can increase the mining of
  low-grade ores at affordable prices, but harmful
  environmental effects can limit this approach.
• Biomining slow, but environmentally less
  destructive
• Ocean mineral resources
• Cost too much to extract
• Squabbles over who owns them (i.e. deposits in
  international waters)
• Environmental effects are poorly understood

28
Sources of Minerals from the Ocean

• Seawater
• Continental shelf deposits
• Hydrothermal vent deposits
• Manganese nodules

Figure 15-17
29

Solutions
Sustainable Use of Nonrenewable Minerals
Do not waste mineral resources.
Recycle and reuse 6080 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. 15-18, p. 351
30
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.

31
Case Study The Ecoindustrial Revolution
Figure 15-19