Post on 18-Jan-2016
Geology and Nonrenewable
Mineral Resources
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.
Major features of the earth’s crust and upper mantle.
Figure 15-2Figure 15-2
Fig. 15-3, p. 337
Spreading center Ocean
trench
Plate movement
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
Plate movement
Collision between two continents
Tect
onic
pl
ate
Oceanic tectonic
plate
Oceanic tectonic plate
Oceanic crust
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.
Figure 15-4Figure 15-4
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 15-4Figure 15-4
Fig. 15-4, p. 338
The San Andreas Fault is an example of a transform fault.
Figure 15-5Figure 15-5
Weathering is an external process that wears the earth’s surface down.
Figure 15-6Figure 15-6
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.
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
Examples are fossil fuels (coal, oil), metallic minerals (copper, iron), and nonmetallic minerals (sand, gravel).
Figure 15-7Figure 15-7
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).
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
The extraction, processing, and use of mineral resources has a large environmental impact.
Figure 15-9Figure 15-9
Fig. 15-10, p. 344
Natural Capital Degradation
Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources
StepsSteps Environmental effectsEnvironmental 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
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.
Machines dig holes and remove ores, sand, gravel, and stone.
Toxic groundwater can accumulate at the bottom.
Figure 15-11Figure 15-11
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 15-12Figure 15-12
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 15-13Figure 15-13
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 15-14Figure 15-14
before after
Larry Gibson on Larry Gibson on the issuethe issue
A positive A positive view view
Scarring and disruption of the land surface
Subsidence Toxin laced mining
wastes Air pollution Acid deposition from
smelting gases
Figure 15-15Figure 15-15
The future supply of a resource depends on its affordable supply and how rapidly that supply is used.
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
A rising price for a scarce mineral resource can increase supplies and encourage more efficient use.
Depletion curves for a renewable resource using three sets of assumptions. Dashed vertical
lines represent times when 80% depletion occurs.
Figure 15-16Figure 15-16
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
Seawater Continental shelf
deposits Hydrothermal vent
deposits Manganese
nodules
Figure 15-17Figure 15-17
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.
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.
Figure 15-19Figure 15-19