Download Chapter 15 Geology and Nonrenewable Mineral Resources Notes

Geology and Nonrenewable
Mineral Resources Notes
Chapter 15
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
Spreading
center
Collision between
two continents
Subduction
zone
Continental
crust
Oceanic
crust
Ocean
trench
Oceanic
crust
Continental
crust
Material cools Cold dense
as it reaches material falls
the outer back through
mantle
mantle
Hot
Mantle
material
convection
rising
cell
through
the
mantle
Two plates move
towards each other.
One is subducted
back into the mantle
on a falling convection
current.
Mantle
Hot outer
core Inner
core
Fig. 15-3, p. 337
GEOLOGIC PROCESSES
• Huge volumes of heated and molten rock
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
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
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
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
ENVIRONMENTAL EFFECTS OF
USING MINERAL RESOURCES
• The extraction, processing, and use of
mineral resources has a large environmental
impact.
Figure 15-9
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
Use
Solid wastes; radioactive
material; air, water, and
soil pollution; noise;
safety and health
hazards; ugliness; heat
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
Transportation,
purification,
manufacturing
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
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
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
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. 15-18, p. 351
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.
The Ecoindustrial Revolution
Figure 15-19