Geology and Mineral Resources (Non-renewable) Chapter 14.
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Transcript of Geology and Mineral Resources (Non-renewable) Chapter 14.
GeologyStudy of the dynamic processes taking place on the earth’s surface and in its interiorThree major concentric zones
Core Innermost zone, extremely hot, solid inner part
surrounded by liquid/molten semisolid
Mantle Lithosphere - the outermost layer of the mantle and
consists of solid rock Asthenosphere – a zone of partly melted rock that flows
Crust Outermost and thinnest zone
Convection cells
The interior of the earth is composed of convection cells that move large volumes of rock and heat in loops within the mantleThese flows of energy and heated material caused the lithosphere to break up into the tectonic plates which move slowly on top of the aesthenosphere
Theory of Plate TectonicsPrior to 1900s scientists believed that Earth’s major features (oceans & continents) were fixed in place1912 Alfred Wegener proposed a revolutionary hypothesis that the world’s continents had once been joined in a single landmass called “Pangea”Evidence to support his theory
Identical rock formations on both sides of the AtlanticFossil evidence
Theory of Plate TectonicsEarth’s lithosphere is divided into plates, most of which are in constant motionTectonic cycle is the sum of the processes that build up and break down the lithosphere
Tectonic plates (2 types Oceanic & Continental)
Plate BoundariesConvergent - collide
Mountains Volcanoes Oceanic trenches
Divergent - pull apart Oceanic ridges
Transform – slide past each other Earthquakes
plate tectonicsplate boundary rap
Volcanoes, Arcs, and Hotspots85% of volcanoes occur along plate boundariesHot spots form when plumes of molten material from the mantle reach the lithosphereWhen plate boundaries move across a hot spot, a chain of volcanoes form, as exemplified by the Hawaiian Islands. As the plate continues to move, a chain of extinct and active volcanoes are developed.Volcanic Arcs – subduction of one plate under another
Oceanic – (2 oceanic plates, one subducts the other creating an oceanic trench)Continental - an oceanic plate is subducted under a land plate creating a mountain range
Volcanoes, Earthquakes, Tsunamis
Mount Saint Helens Eruption 1980 Mt. Saint Helens LandslideNorthridge Earthquake 1994 photos and dataTsunami Japan 2011
Rocks and MineralsMineral: an element or inorganic compound that occurs naturally in the earth’s crust as a crystalline solid (regular repeating 3 dimensional arrangement of the atoms within)
Gold, mercury, sodium chloride, silicon dioxide
Rock: A solid combination of one or more minerals found in the earth’s crustThree major types of rock
Sedimentary rockIgneous rockMetamorphic rock
Sedimentary RockMade of sediments consisting of dead plant and animal remains and tiny particles of weathered and eroded rockSandstone, shale, limestone, dolomite, coalMany fossils are found in this type of rockFormed by pressure
Igneous RockForms below the earth’s surface when magma rises from the mantle and then cools and hardensMake up the greatest percentage of the earth’s crustFrequently contains valuable metal deposits
Granite Lava Rock
Metamorphic Rock
Preexisting rock is subjected to high temperatures or pressure causing the transformation of rocks by reshaping their internal crystalline structure
Slate Marble
Weathering, Erosion, Rock CycleWeathering
Physical, chemical, or biological processes that break down rocks into smaller particles that help build soil
Physical – wind, water, temperature changes Chemical – acidic water (acid rain or naturally acidified) Biological – lichens, roots, burrowing animals
ErosionMaterial is dissolved, loosened, or worn away from one part of the earth’s surface and deposited elsewhere
Rivers, streams, rain, wind, glaciers, burrowing animals
Rock CycleRock moves from one physical state or location to another.Igneous, sedimentary, and metamorphic rocks are continually formed, modified, transported, and destroyed
Rock formation deep in the earth’s crust, then upliftedWeathering and erosionParticles are then transformed into another type of rock
Rock Cycle Animation
Mineral Resources – NonrenewableA naturally high concentration elements or compounds in the earth’s crust that can easily and affordably be extracted and processed into raw materials and then useful productsConsidered nonrenewable b/c they take so long to form2 types
Metallic minerals (gold, silver, platinum, aluminum Nonmetallic minerals (sand/SiO2, limestone/CaCO3)
Know some uses for these:Al, Fe, Mn, Co, Cr, Cu, Au, Phosphate salts
Mineral Ore
Rock that contains a high enough concentrations of a specific mineral, making extraction economically feasible
High grade – higher concentrationLow grade – lower concentration
Reserves The identified resources from which we can extract the mineral profitably at current prices (does not include possible undiscovered resources)
Approximate Supplies of Metal Reserves
Metal Global Reserves Remaining(in years)
US Reserves Remaining(in years)
Iron 120 40
Aluminum 330 0
Copper 65 40
Lead 20 40
Zinc 30 25
Gold 30 20
Nickel 75 0
Cobalt 50 0
Manganese 70 0
Chromium 75 0
Types of MiningSubsurface mining
Minerals located deep beneath the surface of the earth are removed through tunnels and shafts
Slope and shaft Room and pillar/stope and pillar
Surface Mining Deposits are located close to the surface and the overburden (soil or rock above the deposit) is removed to access minerals After minerals are extracted, waste materials called spoils or tailings are dumped into holding ponds, heaped into giant piles, or returned to the original hole
Surface MiningOpen pit – creation of a large pit in the groups that is visible from the earths surface but extends both vertically and horizontally (Copper)Strip mining – remove strips of soil and rockContour strip mining – remove strips of soil in rock using the natural contour of the landscapeMountaintop removal – remove entire top of mountain using explosivesPlacer mining – process of using water to separate river sediments into precious metals and waste (gold, diamonds, tantallum)
Mineral Extraction and Processing
Extraction & processing requires large amounts of:
EnergyWater
Environmental impacts include:
Soil displacement and erosionSolid wasteGreenhouse gasesHuman health hazardsAcid mine drainageDropping water tables
Human Health Impacts
Release of cyanide and mercury into the environmentAcid mine drainageMining is a hazardous occupationBlack lung disease
Distribution of Minerals and ReservesMinerals are not distributed evenly throughout the earth’s land areasUS, Canada, Russia, S. Africa, & Australia supply most of the world’s nonrenewable mineralsConsumption differs greatly b/w LDCs and MDCsChina
Stockpiling 17 rare earth metals such as Tb, Ds needed for advanced technology industry
United StatesHas stockpiles of Cr, Ti, Sn, Mn, Cr, Pt, and Co, b/c total of 20 elements must be imported, but reserves are dwindling
Depletion TimeThe amount of time it takes to use up 80% of the reserves of a mineral at a given rate of useDetermined by two factors
Actual/potential supplyRate of consumption
3 ScenariosNo recycling or reuseRecycling, reuse, better technologyRecycle, reuse, better technologies, new discoveries
Economics of MiningMining becomes economically less feasible due to three factors:
Increasing cost of mining due to quality of oreShortages of water due to water table disturbancesEnvironmental impacts
New forms of mining or alternativesBiominingOcean miningFind Substitutes for minerals
Mining LegislationMining Law of 1872 (General Mining Law)
Regulates the mining of silver, copper, and gold as well as fuelsCompanies can recover ores and fuels from federal landsDesigned to encourage westward expansion, little to no environmental protections
Surface Mining Control and Reclamation Act of 1977Regulates surface mining of coal and the surface effects of subsurface coal miningLand must be disturbed as little as possible during the mining process
TreatiesAntarctic Treaty 1961
Limits activities to peaceful scientific endeavors
Environmental Protection Protocol to the Antarctic Treaty/Madrid Protocol 1990
A moratorium on mineral exploration for a minimum of 50 yearsDesignated Antarctica as a “natural reserve dedicated to peace and society”
U.N. Convention on the Law of the Sea (UNCLOS) 1994
The constitution of the ocean, binding for international waters, protects the resources of the ocean (Mn)