Transcript Mining - strawberryapes

Chapter 14
Crust
35 km (21 mi.) avg., 1,200˚C
Low-velocity zone
100 km (60 mi.)
200 km (120 mi.)
Crust
Mantle
Lithosphere
Solid
10 to 65km
2,900km
(1,800 mi.)
3,700˚C
Outer core
(liquid)
Core
Inner
core
(solid)
100 km
Asthenosphere
(depth unknown)
200 km
5,200 km (3,100 mi.), 4,300˚C
Reykjanes
Ridge
EURASIAN PLATE
JUAN DE
FUCA PLATE
CHINA
SUBPLATE
Transform
fault
PHILIPINE
PLATE
PACIFIC
PLATE
MidIndian
Ocean
Ridge
Transform
fault
INDIAN-AUSTRLIAN PLATE
Southeast Indian
Ocean Ridge
NORTH
AMERICAN
PLATE
COCOS
PLATE
East Pacific
Rise
MidAtlantic
Ocean
Ridge
EURASIAN
PLATE
ANATOLIAN
PLATE
CARIBBEAN
PLATE
ARABIAN
PLATE
AFRICAN
PLATE
SOUTH
AMERICAN
PLATE
Carlsberg
Ridge
AFRICAN
PLATE
Transform
fault
Southwest Indian
Ocean Ridge
ANTARCTIC PLATE
Convergent
plate boundaries
Plate motion
at convergent
plate boundaries
Divergent ( ) and
transform fault (
boundaries
)
Plate motion
at divergent
plate boundaries
 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
 Continental Drift helps to explain how
populations become separate species as the
continents move apart
Lithosphere
Asthenosphere
Oceanic ridge at a divergent plate boundary
Trench
Volcanic island arc
Rising
magma
Subduction
zone
Lithosphere
Asthenosphere
Trench and volcanic island arc at a convergent plate boundary
Fracture zone
Transform
fault
Lithosphere
Asthenosphere
Transform fault connecting two divergent plate boundaries
 Materials are dissolved, loosened, or worn
away from one part of the Earth’s surface to
another
 Process that breaks down rocks into smaller
pieces that can be eroded
 Mechanical (frost weathering)
 Chemical
 Biological
1. Inorganic
2. Occurs naturally
3. Solid
4. Regular crystalline structure
 Combination of minerals
 May be organic
 Can contain fossils
 Forms when magma or lava cools and
hardens
 Intrusive form INSIDE the crust
 Extrusive form on/ outside the crust
 Ex: granite, lava rock
 Formed from sediments that become
compacted
 Ex: coquina, sandstone, shale
 Rock is subjected to high pressure,
temperature, or chemicals
 Ex: anthracite, marble, slate
Volcanoes
Earthquakes
Liquefaction of
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
 Caused by movement of tectonic plates
 P-waves and S-waves
 see earthquake activity
extinct
volcanoes
central
vent
magma
conduit
magma
reservoir
Solid
lithosphere
Upwelling
magma
Partially molten
asthenosphere
Volcanoes
3 Types of Volcanoes
• Composite volcanoes
• Cinder cones
• Shield volcanoes
 To encourage mineral exploration and
mining out West
 Anyone can buy public land (except parks or
wilderness) by patenting it
 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
 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!
 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
 Don’t sell the land
 Lease it for up to 20 years
 Pay royalties on whatever they remove
 Stricter clean up requirements
 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
 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
 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
 Seismic surveys
 Chemical analysis
 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
 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
 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
Open Pit Mine
Dredging
Area Strip Mining
Contour Strip Mining
Subsurface: Underground Coal Mine
 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







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
 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
Steps
Mining
exploration, extraction
Processing
transportation, purification,
manufacturing
Use
transportation or transmission
to individual user,
eventual use, and discarding
Environmental Effects
Disturbed land; mining accidents;
health hazards; mine waste dumping;
oil spills and blowouts; noise;
ugliness; heat
Solid wastes; radioactive material;
air, water, and soil pollution;
noise; safety and health
hazards; ugliness; heat
Noise; ugliness
thermal water pollution;
pollution of air, water, and soil;
solid and radioactive wastes;
safety and health hazards; heat
Subsurface
Mine Opening
Acid drainage from
reaction of mineral
or ore with water
Surface Mine
Runoff of
sediment
Spoil banks
Percolation to groundwater
Leaching of toxic metals
and other compounds
from mine spoil
Leaching
may carry
acids into
soil and
ground
water
supplies
Smelting
Separation
of ore from
gangue
Melting
metal
Metal ore
Conversion
to product
Recycling
Discarding
of product
Surface
mining
Scattered in environment
Fig. 14.8, p. 327
 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
A
Mine, use, throw away;
no new discoveries;
rising prices
Recycle; increase reserves
by improved mining
technology, higher prices,
and new discoveries
Production
B
Recycle, reuse, reduce
consumption; increase
reserves by improved
mining technology,
higher prices, and
new discoveries
C
Present
Depletion
time A
Depletion
time B
Time
Depletion
time C