GEOLOGY and MINERAL RESOURCES

Geologic Processes: Structure of the Earth

Geologic Processes: Structure of the Earth

Fig. 4-7 p. 60

3

Major Rock Groups• Igneous

– Formed from a melt (molten rock)– Plutonic (intrusive):slow cooling and crystallization– Volcanic (extrusion): quick cooling at the surface

• Sedimentary– Formed at the Earth’s surface

• Metamorphic– Changed by pressure, temperature and fluids.

Fig. 2.9

MAGMA

5

MAGMA

Crystallization

IGNEOUS

6

MAGMA

IGNEOUS

Plutonic

Crystallization

7

MAGMA

Volcanic

IGNEOUS

Plutonic

Crystallization

8

MAGMA

Volcanic

IGNEOUS

Plutonic

Uplift

Crystallization

Weathering

External Earth ProcessesExternal Earth Processes

Erosion (wind, water, gravity) Erosion (wind, water, gravity)

Mechanical weatheringMechanical weathering

Frost wedgingFrost wedging

Chemical weathering (precipitation & Moisture)

Chemical weathering (precipitation & Moisture)

Biological weathering (root wedging,borrowing)

Biological weathering (root wedging,borrowing)

10

MAGMA

Volcanic

IGNEOUS

Plutonic

SEDIMENT

Uplift

Crystallization

Weathering SEDIMENT

11

MAGMA

Volcanic

IGNEOUS

Plutonic

SEDIMENT

SEDIMENTARY

Uplift

Crystallization

WeatheringErosion

Transport

Deposition

12

MAGMA

Volcanic

IGNEOUS

Plutonic

SEDIMENT

SEDIMENTARY

Uplift

Crystallization

WeatheringErosion

Transport

Deposition

13

MAGMA

Volcanic

IGNEOUS

Plutonic

SEDIMENT

SEDIMENTARY

METAMORPHIC

UpliftBurial

Increased P&T

Crystallization

WeatheringErosion

Transport

Deposition

14

MAGMA

Volcanic

IGNEOUS

Plutonic

SEDIMENT

SEDIMENTARY

METAMORPHIC

UpliftBurial

Increased P&T

MeltingCrystallization

WeatheringErosion

Transport

DepositionCan you see

any shortcuts?

15

MAGMA

Volcanic

IGNEOUS

Plutonic

SEDIMENT

SEDIMENTARY

METAMORPHIC

UpliftBurial

Increased P&T

MeltingCrystallization

WeatheringErosion

Transport

Deposition

• The rock cycle demonstrates the relationships among the three major rock groups

• It is powered by the interior heat of the Earth

• The energy from the sun

• It involves processes on the Earth’s surface as well as the Earth’s interior.

In Conclusion…

Features of the Crust and Upper Mantle

Plate TectonicsPlate Tectonics

Divergent boundaryDivergent boundary

Convergent boundaryConvergent boundary

Subduction zoneSubduction zone

Transform faultTransform fault

Fig. 16-5 p. 336

• Spreading ridges– As plates move apart new material is erupted to

fill the gap

Divergent Boundaries

• Iceland has a divergent plate boundary running through its middle

Iceland: An example of continental rifting

• There are three styles of convergent plate boundaries– Continent-continent collision– Continent-oceanic crust collision– Ocean-ocean collision

Convergent Boundaries

• Forms mountains, e.g. European Alps, Himalayas

Continent-Continent Collision

Himalayas

• Called SUBDUCTION

• Area is called the subduction zone

Continent-Oceanic Crust Collision

• Where plates slide past each other

Transform Boundaries

Above: View of the San Andreas transform fault

Earth’s Major Tectonic Plates

Natural Hazards: EarthquakesNatural Hazards: Earthquakes

Features Features

Magnitude Magnitude

Aftershocks Aftershocks

Primary effects Primary effects

Secondary effects Secondary effects

Expected Earthquake Damage

Fig. 16-7 p. 337Fig. 16-7 p. 337

CanadaCanada

United StatesUnited States

No damage expectedNo damage expected

Minimal damageMinimal damage

Moderate damageModerate damage

Severe damageSevere damage

Natural Hazards: Volcanic EruptionsNatural Hazards: Volcanic Eruptionsextinct

volcanoesextinct

volcanoes

magmareservoir

centralvent

magmaconduit

SolidlithosphereSolidlithosphere

Upwellingmagma

Partially moltenasthenosphere

Volcanic Eruptions

• Pyroclastic Flow – cloud of ash and debris– Travel at hundreds of mph– Hundreds of degrees

Volcanic Eruptions

• Lahar – mud flows which are very destructive to landscape

Volcanic Eruptions

• “Ash” emitted includes small stones• Very dense• Chokes life• Blots out sunlight• Causes wide range temperature drops

http://www.youtube.com/watch?v=UK--hvgP2uY

Tsunami

• “Harbor Wave”

Nonrenewable Resource

• Resource that exists in a fixed amount in various places in the Earth’s crust and has the potential for renewal only by geological, physical and chemical processes taking place over hundreds of millions of years.

• Mineral Resources – naturally occurring, inorganic solid in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost.

Nonrenewable Mineral ResourcesNonrenewable Mineral Resources

Metallic ores – (Fe, Cu, Al)Metallic ores – (Fe, Cu, Al)

Non-metallic – (salt, gypsum, clay, sand, PO4)

Non-metallic – (salt, gypsum, clay, sand, PO4)Energy resources – (coal,

radioactive isoptopes, oil, natural gas) – typically not mineral resources

Energy resources – (coal, radioactive isoptopes, oil, natural gas) – typically not mineral resources

Nonrenewable Mineral Resources: USGS Categories

Nonrenewable Mineral Resources: USGS Categories

Identified – know location, quality and quantity

Identified – know location, quality and quantity

Undiscovered -inferred

Undiscovered -inferred

Reserves -known location, affordable extraction

Reserves -known location, affordable extraction Other -identified/ undiscovered but NOT reserved

Other -identified/ undiscovered but NOT reserved

Finding Nonrenewable Mineral ResourcesFinding Nonrenewable Mineral Resources

Satellite and air imagerySatellite and air imagery

MagnetometersMagnetometers

Gravity differencesGravity differences

Radiation detectorsRadiation detectors

Seismic surveysSeismic surveys

Chemical analysesChemical analyses

Extracting Nonrenewable Mineral Resources:

Extracting Nonrenewable Mineral Resources:

Open-pit (surface mining)Open-pit (surface mining)

Area strip (surface mining)Area strip (surface mining)

Contour strip (surface mining)Contour strip (surface mining)

Dredging (surface mining)Dredging (surface mining)

Room-and-pillar (subsurface mining)Room-and-pillar (subsurface mining)

Longwall (subsurface mining)Longwall (subsurface mining)

Open Pit Mining (surface)

• Machines remove mineral resource.

Dredging (surface)

• Dig underwater mineral deposits

Area Strip Mining (surface)

• Strip mining in flat landscape areas.

Contour Strip Mining (surface)• Creation of “terraces” along contour elevations

where overburden is removed and a high wall is created which is very erodable.

Mountaintop Removal

• Dragline cuts the top of the mountain off and dumps it into the surrounding valley.

Room and Pillar (subsurface)• This method creates shafts dug below the

surface that are then blasted with dynamite to create tunnels. The ore/coal can then be hauled to the surface.

Room & Pillar Method

Room and pillar mining is commonly done in flat or gently dipping bedded ores. Pillars are left in place in a regular pattern while the rooms are mined out. In many room and pillar mines, the pillars are taken out, starting at the farthest point from the mine haulage exit, retreating, and letting the roof come down upon the floor. Room and pillar methods are well adapted to mechanization, and are used in deposits such as coal, potash, phosphate, salt, oil, shale, and bedded uranium ores.

Longwall (subsurface)

• Dig a narrow tunnel supported by removable pillars. The benefit is that no tunnels are left behind to collapse once abandoned.

Subsurface vs. Surface Mining• Subsurface mining is less environmentally

destructive than surface mining BUT

Subsurface mining is more dangerous to workers. Walls collapse, explosions from gas, inhalation of mining dust leads to “black lung”

U.S. 1872 Mining Law

• Encourages mining in the USA for gold, silver, lead, copper, uranium, and hard rock minerals.

• People OR Corporations can patent public land by:a. Declaring it has valuable mineralsb. Spending $500 to improve land for mineral developmentc. Filing a claim for the landd. Pay US Government $2-5/acre!

MINERALS NEVER NEED TO BE EXTRACTEDCan sell land to extraction companies for millions of dollars (usually foreign companies) who pay no royalties to US Government.

Colorado Case Study

• Canadian Company bought a site for a few thousand dollars.

• They spent 1 million dollars developing the site, removed 98 million dollars worth of gold.

• Acid mine drainage leached into the Alamusa River.• Company declared bankruptcy and abandoned the site

leaving the EPA Superfund to pay for clean up (= taxpayer money)

• Costs = 40,000/day to contain toxic waste• Also contaminates irrigation water (no way to clean up)

USA 1872 Mining Law Continued

• If public land is designated as valuable wilderness area, the government can buy back the land (our tax $) at “market value”.

• Any lands mined do not have to be reclaimed. They can be left in highly erodable states with leaching toxins into air, water, and soil.

Mining Company Practices

• Companies will usually:1. Mine land2. Abandon the land3. File for bankruptcy4. Leave taxpayers with cleanup bill (33-72 billion dollars

per year!5. Superfund sites (Super funds that the EPA designates

to be used for hazardous waste cleanup)6. If groundwater becomes contaminated, it can’t be

cleaned up and there is no way of estimated the cost to humans!

Should the mining law of 1872 be changed?

• Environmentalists propose amendments to the law:1. Lease land for 20 years instead of buying it.2. Conduct full NEPA Environmental Assessment of impacts before mining

begins.3. Set strict standards for controlling pollution and protecting environment

from toxins and erosion.4. Company should post environmental insurance bond to cover estimated

environmental damage and clean up costs in the future.5. Companies should pay rent to cover costs for government monitoring of

lands.6. 12.5% royalty should be paid to government on gross sales. Mining

companies claim that charging royalties and forcing them to clean up their mess will not make it economically feasible to mine in USA anymore. This will lead to a decrease in jobs for Americans. Environmentalists claim mining companies will still make profits, just not as much!

7. Make mining companies legally and financially responsible for clean up.

Surface Mining Control and Reclamation Act

Established 1977Established 1977

Mine lands must be restored to pre-mining conditions

Mine lands must be restored to pre-mining conditions

Taxes on mining companies to restore pre-1977 sites

Taxes on mining companies to restore pre-1977 sites

Limited successLimited success

Environmental Effects of Mining Mineral Resources

Environmental Effects of Mining Mineral Resources

Disruption of land surfaceDisruption of land surfaceSubsidenceSubsidenceErosion of solid mining wasteErosion of solid mining wasteAcid mine drainageAcid mine drainageAir pollutionAir pollutionStorage and leakage of liquid mining

waste

Storage and leakage of liquid mining waste

Environmental Degradation From Processing of Minerals

• Processing includes transportation, purification, and manufacturing of minerals

• Smelting impacts air, water, and soil “What goes up must come back down”

Smelting

desired ore Gange (waste)

Beneficiation – separation of additional ore from gange

Ore Tailings (toxic metals)

Environmental Impacts

• Air and noise pollution – Dust created by mining and

loading/unloading– Machine causes noise pollution and

damage nearby structures

Environmental Impacts

• Water Contamination– Water picks up and dissolves toxic

substances (arsenic)– Sulfur and water – diluted sulfuric acid

• Acid Mine Drainage - AMD

Environmental Impacts

• “Mountain Dew Teeth”

Environmental Impacts

• Displacement of Wildlife– Stripping of plant life– Animals leave area– New ecosystem created after– Destroy river and sea bottoms

Environmental Impacts

• Erosion and Sedimentation– Sediments find way into streams– Choke stream life– Degrades water quality

Environmental Impacts

• Soil Degradation– Deeper soil layers added to

top– Decreases richness of

original soil

• Subsidence (sink holes)– Sinking of regions of ground

with no horizontal movementhttp://www.theblaze.com/stories/2013/03/01/man-goes-missing-in-florida-when-bedroom-falls-into-sinkhole/

Environmental Impacts

• Underground Mine Fires– Last decades and even centuries– Australian fire – 2,000 Years!!!!!– Gas and smoke emitted

Smelting Copper

• Cu Sox soot (SO2) + As + Cd + Pb

Scrubbers and electrostatic precipitators are expensive technology that help to remove the harmful substances before being released into the atmosphere.

Environmental Degradation From End-Use

• Transportation to user, final use, and discarding after use.

(a) Fossil fuels are burned during transportation of end product.

(b) Product must be discarded in:1. landfill where metals corrode and pollute land and water.2. Recycle and reuse (In USA, most goes to landfill, but recycling of solid waste is improving each year.

Environmental Effects of Mining Mineral Resources

Environmental Effects of Mining Mineral Resources

Fig. 16-14 p. 344

More Environmental Impacts of Nonrenewable Mineral Resources

Surface miningSurface mining Subsurface miningSubsurface mining

Overburden Overburden

SpoilSpoil

Open-pitOpen-pit

DredgingDredging

Strip miningStrip mining

Room and pillarRoom and pillar

LongwallLongwall

Refer to Figs. 15-4 and 15-5, p. 341 and 342

Refer to Figs. 15-4 and 15-5, p. 341 and 342

Processing Mineral ResourcesProcessing Mineral Resources

Ore mineral – what is wantedOre mineral – what is wanted

Gangue – waste around oreGangue – waste around ore

Tailings - leftover Tailings - leftover

Smelting – process to remove Smelting – process to remove Refer to Fig. 16-15 p. 344

Supplies of Non-Renewable Resources

• Dependent on:(a) actual or potential supplies(b) rate of use

Minerals become economically depleted when the cost of extraction is greater that the profit.

What de we do? We have choices(a) refuse, reduce, reuse, recycle(b) find substitute

Depletion of Mineral ResourcesDepletion of Mineral Resources

Depletion Time – the time it takes to use up a certain proportion (80%) of the reserves of a mineral at a given rate.

Common Projection Rate – “Reserve to Production Ratio” = the number of years that proven reserves of a particular non-renewable resource will last at a current production rate.

Economics of Mineral Resources• Free Market when supply is greater than

demand = cheap costs to consumers.Definition: a market in which supply and demand are

unregulated except by the country's competition policy, and rights in physical and intellectual property are upheld.

In a free market there are:(a)Fulfillment: the process of responding to customer

inquiries, orders, or sales promotion offers. (b)Future: a contract to deliver a commodity at a future

date. (c)Futures market: a market for buying and selling

securities, commodities, or currencies that tend to fluctuate in price over a period of time.

Why are items made of Zn, Pb, Hg, Fe, and Al so cheap, if their depletion times are

nearing?• Fe/Al – 100 years in world reserves.• Hg/Zn/Pb – 20 years in world reserves.1. Subsidies – to promote economic growth and national

security. Is there really a free market?2. Harmful environmental costs of mining and processing

are not included in their market price. NO TRUE COSTING!

3. Ore grades have been lowered. Example 1900 Cu penny – 5% by weight, now 0.5% by weight. Ask yourself…are reserve to ration production numbers real?

4. As technology improves we learn more about where more minerals may be on Earth and don’t have to impart tremendous damage to landforms during exploration activities.

Global Non-Fuel Minerals

• Mostly in the USA, Canada, Australia, South Africa, and the Republics of the former Soviet Union.

• Western Europe – depends mostly on minerals from Africa.

• USA imports 24 of the 42 most important non-fuel minerals.

• Concerns: manganese, cobalt, platinum, and chromium – USA has little or no reserves and we get them from unstable African nations.

• USA uses these minerals for autos, airplanes, engines, satellites, and sophisticated weapons!