1. Unit 7 Geology & Mining Resources
Chapter 14

2. Mantle Core Crust Lithosphere Asthenosphere
Low-velocity zone
Solid
Outer core
(liquid)
Inner
core
(solid)
35 km (21 mi.) avg., 1,200˚C
2,900km
(1,800 mi.)
3,700˚C
5,200 km (3,100 mi.), 4,300˚C
10 to 65km
100 km
200 km
100 km (60 mi.)
200 km (120 mi.)
Lithosphere
Asthenosphere
(depth unknown)

3. INDIAN-AUSTRLIAN PLATE
EURASIAN PLATE
CHINA
SUBPLATE
PHILIPINE
PLATE
INDIAN-AUSTRLIAN PLATE
PACIFIC
JUAN DE
FUCA PLATE
COCOS
CARIBBEAN
NORTH
AMERICAN
SOUTH
EURASIAN
ANATOLIAN
ARABIAN
AFRICAN
Carlsberg
Ridge
Southwest Indian
Ocean Ridge
ANTARCTIC PLATE
Transform
fault
East Pacific
Rise
Mid-
Indian
Ocean
Southeast Indian
Atlantic
Reykjanes
Divergent ( ) and
transform fault ( )
boundaries
Convergent
plate boundaries
Plate motion
at convergent
at divergent

4. Theory of Plate Tectonics
Explains and unifies many geologic theories
1960’s
Basically describes how the Earth’s crust is made of plates that move around on top of the upper liquid portion of the mantle

5. Plate Tectonics and Evolution
Continental Drift helps to explain how populations become separate species as the continents move apart

6. Oceanic ridge at a divergent plate boundary
Lithosphere
Asthenosphere
Oceanic ridge at a divergent plate boundary

7. Trench and volcanic island arc at a convergent plate boundary
Lithosphere
Rising
magma
Asthenosphere
Subduction
zone
Trench and volcanic island arc at a convergent plate boundary

8. Transform fault connecting two divergent plate boundaries
Fracture zone
Transform
fault
Lithosphere
Asthenosphere
Transform fault connecting two divergent plate boundaries

9. Erosion
Materials are dissolved, loosened, or worn away from one part of the Earth’s surface to another

10. Weathering
Process that breaks down rocks into smaller pieces that can be eroded
Mechanical (frost weathering)
Chemical
Biological

11. Minerals Inorganic Occurs naturally Solid
Regular crystalline structure

12. Rocks
Combination of minerals
May be organic
Can contain fossils

14. Igneous Rock Forms when magma or lava cools and hardens
Intrusive form INSIDE the crust
Extrusive form on/ outside the crust
Ex: granite, lava rock

15. Sedimentary Rock Formed from sediments that become compacted
Ex: coquina, sandstone, shale

16. Metamorphic Rock
Rock is subjected to high pressure, temperature, or chemicals
Ex: anthracite, marble, slate

17. Volcanoes
Earthquakes

18. Earthquakes Liquefaction of Two adjoining plates recent sediments
causes buildings
of sink
Two adjoining plates
move laterally along
the fault line
Earth movements
Cause flooding in
Low-lying areas
Landslides may
occur on
hilly ground
Shock
waves
Epicenter
Focus
Earthquakes

19. Earthquakes Caused by movement of tectonic plates P-waves and S-waves
see earthquake activity

20. Richter Scale

21. Volcanoes extinct volcanoes central vent magma magma reservoir conduit
Solid
lithosphere
Upwelling
magma
Partially molten
asthenosphere
Volcanoes

22. 3 Types of Volcanoes
Composite volcanoes
Cinder cones
Shield volcanoes

23. General Mining Law of 1872
To encourage mineral exploration and mining out West
Anyone can buy public land (except parks or wilderness) by patenting it

24. General Mining Law of 1872
Must say they think there are minerals there and that they will spend at least $500 to improve the land for mineral development
Pay $2.50- $5.00 an acre
Then they can do whatever they want with it

25. General Mining Law of 1872
Mining companies (F & D) remove $2-3 BILLION in resources each year from land they got this way!
About 20% of companies with mining rights on US public lands are FOREIGN!

26. General Mining Law of 1872
Modified in 1992 to require companies to post bonds to cover the full amount of a clean up in case the company goes bankrupt
Clean up would cost taxpayers $33-72 Billion
Lobbyists are trying to weaken these laws

27. Environmental Concerns
Don’t sell the land
Lease it for up to 20 years
Pay royalties on whatever they remove
Stricter clean up requirements

28. Nonrenewable Mineral Resources
Concentration of naturally occurring material in or on the crust that can be extracted & processed at a reasonable cost
Take a long time to produce
Metallic and nonmetallic
Energy

29. Nonrenewable Mineral Resources
Identified Resources- we know where they are and how much there is
Reserves- resources we can extract at a reasonable price
Undiscovered Resources- potential supplies, don’t know for sure it is there or how much there is
Other- discovered or undiscovered but not a reserve

30. How do we find resources?
Aerial photos and satellite images
Detect radiation from radioactive deposits (Uranium)
Magnetometer to detect changes in magnetic field (Iron ore)
Gravimeter to detect changes in gravity caused by different densities of rock

32. Underground Methods
Seismic surveys
Chemical analysis

33. Tailings – gangue that has been separated from the desired mineral
Ore – a rock containing enough metallic minerals to be mined profitably
Mineral + unwanted gangue
Tailings – gangue that has been separated from the desired mineral
Reserves – identified resources from which nonrenewable minerals can be extracted profitably

34. Ore Deposits
The most common way that ore deposits form is through hydrothermal processes:
especially at divergent boundaries  superheated seawater dissolves metals
hydrothermal vents support marine ecosystems based on chemosynthesis
sedimentary sorting based on density (panning for gold)
evaporite mineral deposits  water evaporates leaving minerals
residual deposits  left when soluble minerals are washed away thereby concentrating insoluble minerals nonrenewable

36. Removing Mineral Resources
Overburden of soil and rock is removed and discarded as spoil
Types of Surface Mining:
Open-pit
Dredging of underwater mineral deposits
Area strip mining
Contour strip mining
Subsurface mining
disturbs less than 1/10 as much land as surface mining
more hazardous, more expensive, less productive

37. Open Pit Mine

38. Dredging

39. Area Strip Mining

40. Contour Strip Mining

41. Subsurface: Underground Coal Mine

42. Environmental Impacts of Mining
Tailings are the waste materials left over after removing the minerals from ore.
Tailings are sometimes reprocessed.
Common contents of tailings:
Arsenic
Barite
Calcite
Cyanide
Fluorite
Mercury
Pyrite
Quartz

43. Environmental Impacts of Mining
Disruption of land
Subsidence of land
Wind or water erosion of mineral waste
Acid mine drainage  sulfuric acid released
Emission of toxic chemicals into the air
Leakage of toxic wastes into waterways
Smelting  separates the metals from other substances  made into products which are used and then recycled or discarded
this process emits huge quantities of air pollutants (without effective pollution controls)
water pollution
produces hazardous wastes

44. Restoration & Reclamation
Reclamation – make land suitable for another purpose (agriculture, recreation, etc)
Restoration – restore native habitat
Regrading the land to original topography
Replacing topsoil
Planting native vegetation

45. Steps Environmental Effects Mining Processing Use
Disturbed land; mining accidents;
health hazards; mine waste dumping;
oil spills and blowouts; noise;
ugliness; heat
Mining
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

46. Percolation to groundwater Leaching of toxic metals
Subsurface
Mine Opening
Surface Mine
Runoff of
sediment
Acid drainage from
reaction of mineral
or ore with water
Spoil banks
Percolation to groundwater
Leaching may carry
acids into soil and
ground
water supplies
Leaching of toxic metals
and other compounds
from mine spoil

47. Scattered in environment
Smelting
Separation
of ore from
gangue
Melting
metal
Conversion
to product
Metal ore
Recycling
Surface
mining
Discarding
of product
Fig. 14.8, p. 327
Scattered in environment

48. Supplies of Mineral Resources
Economic depletion
Mining lower grade ores, mining ocean floor. seawater extraction  expensive!
Mining is subsidized in US  government tax deductions, depletion allowances, Mining Law of 1872
Sagebrush Rebellion in the 80’s  miners, ranchers, etc. pushed for opening up federal public lands for use
72% of US Public lands are in Alaska; 22% are in western states
Using alternative products  ceramics, plastics

49. Recycle; increase reserves by improved mining
Mine, use, throw away;
no new discoveries;
rising prices
Recycle; increase reserves
by improved mining
technology, higher prices,
and new discoveries B
Production
Recycle, reuse, reduce
consumption; increase
reserves by improved
mining technology,
higher prices, and
new discoveries C
Present
Depletion
time A
Depletion
time B
Depletion
time C
Time