2. Civilizations exists by geological consent, subject to change without notice Will Durant

3. Geology and Mineral Resources
Unit 11

4. Earth is a Dynamic Planet
Geology: study of processes taking place in
earth’s interior and on its surface.
core: hot, solid center of planet
mantle: surrounds core; rocky near interior, magma (molten rock) near exterior-asthenosphere
crust: thinnest, outermost zone
-continental crust (includes continental ocean shelf)
-oceanic crust: 71% of crust
lithosphere: crust and rigid mantle

5. Oceanic crust (lithosphere) Abyssal plain Continental slope
Folded mountain belt
Volcanoes
Abyssal plain
Abyssal floor
Oceanic ridge
Abyssal floor
Abyssal hills
Trench
Craton
Oceanic crust (lithosphere)
Abyssal plain
Continental slope
Continental shelf
Continental rise
Mantle (lithosphere)
Continental crust (lithosphere)
Mantle (lithosphere)
Figure 15.2
Natural capital: major features of the earth’s crust and upper mantle. The lithosphere, composed of the crust and outermost mantle, is rigid and brittle. The asthenosphere, a zone in the mantle, can be deformed by heat and pressure.
Mantle (asthenosphere)
Fig. 15-2, p. 336

6. Tectonic Plates Tectonic plates: plates of lithosphere
created by convection currents in mantle
move slowly on top of asthenosphere
interaction of plate boundaries create earthquakes, volcanoes, mountains

7. The Earth’s Major Tectonic Plates
Figure 15-4

8. Tectonic plate Inner core
Spreading center
Collision between two continents
Oceanic tectonic plate
Ocean trench
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
Figure 15.3
Natural capital: the earth’s crust is made up of a mosaic of huge rigid plates, called tectonic plates, which move around in response to forces in the mantle.
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

9. Plate Boundaries 3 types of plate boundaries:
divergent: oceanic plates moving apart,
molten rock flows up into the void, creates oceanic
ridges (and new crust)
ex. Mid-Atlantic Ridge
convergent: colliding plates
-subduction zone: denser oceanic plate sinks beneath a continental plate
ex. “Ring of Fire” in Western Pacific Ocean
-trench: colliding oceanic plates
-mountains: colliding continental plates
ex. Himalayas

10. Plate Boundaries Transform fault: plates sliding past each other
ex. San Andreas Fault (California), New Madrid Fault (us)

11. Transform fault Rising magma
Trench
Volcanic island arc
Transform fault
Lithosphere
Rising magma
Subduction zone
Lithosphere
Lithosphere
Asthenosphere
Asthenosphere
Asthenosphere
Figure 15.4
Natural capital: 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 from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on?
Divergent plate boundaries
Convergent plate boundaries
Transform faults
Fig. 15-4b, p. 338

12. Internal Geologic Processes
form mountains, volcanoes, earthquakes

13. Internal Geologic Processes
volcanoes: weak area in crust
-magma reaches surface through a fissure
-release lava, ash, CO₂ and SO₂ gases
ex. Mount Pinatubo
earthquakes: movement of plates at transform boundaries
-seismic wave: outward movement of energy from focus of quake
-epicenter: earth’s surface above focus
-tsunamis: ocean floor faults that suddenly rise or fall

15. External Geologic Processes
driven by solar radiation, gravity
weathering: physical, chemical, biological processes that break down rock into soil
-rock: solid combination of one or more mineral
-rock types: sedimentary, igneous, metamorphic

16. Erosion Transportation Heat, pressure, stress Magma (molten rock)
Weathering
Deposition
Igneous rock Granite, pumice, basalt
Sedimentary rock Sandstone, limestone
Heat, pressure
Cooling
Heat, pressure, stress
Magma (molten rock)
Figure 15.8
Natural capital: the rock cycle is the slowest of the earth’s cyclic processes. The earth’s materials are recycled over millions of years by three processes: melting, erosion, and metamorphism, which produce igneous, sedimentary, and metamorphic rocks. Rock from any of these classes can be converted to rock of either of the other two classes, or can be recycled within its own class. QUESTION: List three ways that the rock cycle benefits your lifestyle.
Melting
Metamorphic rock Slate, marble, gneiss, quartzite
Fig. 15-8, p. 343

17. Mineral Resources Mineral resource: useful inorganic material from
crust; 2 major types:
1. metallic (aluminum, gold, lead, nickel, silver)
-ore: rock containing concentration of valued mineral; may be high-grade (lots of mineral) or low-grade (small amounts of mineral)
2. nonmetallic (sand, limestone, talc, clay, salt)
all minerals are considered nonrenewable
country’s standard of living is tied to mineral availability

18. Mineral Use
Al: packaging, structural material in cars, planes Fe: make steel for buildings, vehicles Cu: electrical, communications wiring Au: electronics, jewelry, medical implants Sand: glass, bricks, concrete Limestone: concrete, cement

19. General Classification of Nonrenewable Mineral Resources
U.S. Geological Survey (USGS) classifies mineral
resources into 4 major categories:
Identified: known location, quantity, quality based on direct evidence.
Undiscovered: potential supplies are assumed to exist.
Reserves: identified resources that can be extracted profitably.
Other: undiscovered resources not classified as reserves

20. General Classification of Nonrenewable Mineral Resources
{Examples are fossil
fuels (coal, oil),
metallic minerals
(copper, iron), and
nonmetallic minerals
(sand, gravel)}.
Figure 15-7

21. Mining Methods of removing minerals, fossil fuels:
surface (strip) mining: depends on resource sought, topography
-involves removal of vegetation and overburden: overlying soil, rock
-excess soil is dumped in spoils on land

22. Mining (cont’d) mountaintop removal: exposes coal seams
-requires draglines (trucks with huge buckets)
-spoils are dumped in valleys, rivers, streams
open-pit: creates huge holes to remove metals (copper), sand, stone

23. Mining (cont’d)
subsurface: underground metals, coal are removed through tunnels, shafts
-requires explosives, exposure to poisonous gases, methane, lung-damaging dust

24. Environmental Effects of Mining
(almost all degradation by mining is long-term)
Strip mining: loss of topsoil, spoil banks are easily eroded. Return to ecosystem is slow.
Mountain top removal: destroys forests, buries streams, toxic wastewater can release mercury, arsenic, loss of property value, well contamination.
(mercury used to separate gold from stream sediments represents the 2nd worst human-related source of mercury pollution)

25. Environmental Effects of Mining
Sub-surface mining: degrades biodiversity (especially in rainforest). Clean up is possible, but costly.
Smelting: heating ores to release metals emits large quantities of sulfur dioxide-acid rain/acid mine drainage, green- house gases

26. Environmental Effects of Mining
Cyanide Solution Mining/Heap-Leach Extraction: runoff of cyanide in gold extraction creates toxic ponds (can infiltrate groundwater)

27. Human Health Impacts of Mining
Black-lung disease: inhalation of coal dust from subsurface mining
Mercury poisoning: ingestion of Hg from fish
Cyanide poisoning: exposure to smoke, or ingestion in water.

28. Mineral Availability Abundant: Al, Fe
Scarce: Mn, Cr, Co, Pt (strategic metals)
(-South Africa is largest producer of Cr, Pt
-US relies on these for economy, military,
but has limited reserves)
US, Canada, Russia, South Africa, Australia supply most of world’s mineral resources
China has most of rare earth metals

29. Minerals from the Ocean
Occur in low concentrations
Include Cu, Fe, W (tungsten), Pt, diamonds
Rarely mined due to:
-expense of extraction
-rights disputes
-concern about disruption to food chain
-risk to food supply near coast

30. Black smoker White smoker Sulfide deposits Magma White clam White crab
Figure 15.17
Natural capital: hydrothermal deposits form when mineral-rich superheated water shoots out of vents in solidified magma on the ocean floor. After mixing with cold seawater, black particles of metal compounds precipitate out and build up as chimneylike mineral deposits around the vents. A variety of organisms, supported by bacteria that produce food by chemosynthesis, exist in the dark ocean around these black smokers.
White crab
Tube worms
Fig , p. 350

31. 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

32. Sustainable Mineral Use
Substitution: silicon, plastics, ceramics can replace some metals
Nanotechnology; create materials out of atoms, molecules
Recycle, reuse: ex. recycling Al produces 95% less air, water pollution
Reduce mining subsidies/increase subsidies for recycling
Include cost of environmental damage from mining in prices of items.

33. 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 nonrenewable resources
-potential biological concerns
(nanoparticles can cross the
placenta, penetrate lung tissue,
etc)
Figure 15-1

34. US Mining Laws
The General Mining Law of 1872: encouraged exploration, mining of minerals
-enables corporations to obtain large tracts of public land cheaply without paying royalties or cleanup fees
The Surface Mining Control and Reclamation Act of 1977: requires mined land to be restored to pre-mining conditions
-proper disposal of mining wastes
-re-contouring land
-replanting vegetation
Restored areas are known as brownfields

35. Exam Focus
Major geologic processes occurring within the earth and on its surface
Rocks, and how are they recycled by the rock cycle
Type of formation from diverging ocean plates
Type of formation from converging continental plates
Example of transform fault
Weathering from wind, water, heat

36. Exam Focus (cont’d)
Definition of an ore (high and low-grade); definition of an alloy
Classification of minerals (renewable/non)
Types of mining and harmful environmental and human health effects results from each
-specifically mining source of air and water pollution associated with heating ores
-disease associated with subsurface mining
Environmental effects of smelting
Nonmetal used in glass, bricks, concrete

37. Exam Focus 4 reasons the ocean is not mined for minerals
Ways minerals can be used sustainably
Which mineral substitute still uses oil, fossil fuels
Know the US Surface Mining Control and Reclamation Act of 1977