Presentation on theme: "GEOLOGY and MINERAL RESOURCES. Geologic Processes: Structure of the Earth Fig. 4-7 p. 60."— Presentation transcript:
GEOLOGY and MINERAL RESOURCES
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 Crystallization IGNEOUS
6 MAGMA IGNEOUS Plutonic Crystallization
7 MAGMA Volcanic IGNEOUS Plutonic Crystallization
8 MAGMA Volcanic IGNEOUS Plutonic Uplift Crystallization Weathering
11 MAGMA Volcanic IGNEOUS Plutonic SEDIMENT SEDIMENTARY Uplift Crystallization Weathering Erosion Transport Deposition
12 MAGMA Volcanic IGNEOUS Plutonic SEDIMENT SEDIMENTARY Uplift Crystallization Weathering Erosion Transport Deposition
13 MAGMA Volcanic IGNEOUS Plutonic SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Crystallization Weathering Erosion Transport Deposition
14 MAGMA Volcanic IGNEOUS Plutonic SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Melting Crystallization Weathering Erosion Transport Deposition Can you see any shortcuts?
15 MAGMA Volcanic IGNEOUS Plutonic SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Melting Crystallization Weathering Erosion 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 Tectonics Divergent boundary Convergent boundary Subduction zone Transform fault Fig 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
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
Expected Earthquake Damage Fig p. 337 Canada United States No damage expected Minimal damage Moderate damage Severe damage
Natural Hazards: Volcanic Eruptions extinct volcanoes extinct volcanoes magma reservoir central vent magma conduit Solid lithosphere Solid lithosphere Upwelling magma Partially molten asthenosphere
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 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 Resources 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
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 Resources Satellite and air imagery Magnetometers Gravity differences Radiation detectors Seismic surveys Chemical analyses
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 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 minerals b. Spending $500 to improve land for mineral development c. Filing a claim for the land d. Pay US Government $2-5/acre! MINERALS NEVER NEED TO BE EXTRACTED Can 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 land 2.Abandon the land 3.File for bankruptcy 4.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 % 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 1977 Mine lands must be restored to pre-mining conditions Taxes on mining companies to restore pre-1977 sites Limited success
Environmental Effects of Mining Mineral Resources Disruption of land surface Subsidence Erosion of solid mining waste Acid mine drainage Air pollution 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 oreGange (waste) Beneficiation – separation of additional ore from gange OreTailings (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 movement 1/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 So x soot (SO 2 ) + 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 Fig p. 344
More Environmental Impacts of Nonrenewable Mineral Resources Surface mining Subsurface mining Overburden Spoil Open-pit Dredging Strip mining Room and pillar Longwall Refer to Figs and 15-5, p. 341 and 342
Processing Mineral Resources Ore mineral – what is wanted Gangue – waste around ore Tailings - leftover Smelting – process to remove Refer to Fig 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 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!