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

Plate Boundaries

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

Ring of Fire

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

Subsurface Mining Stope &Pillar/Room & Pillar

Slope and Shaft

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)

Open Pit Copper Mine

Contour Strip Mining

Mountaintop Removal

Placer Mining

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

Impacts from mining, processing and use

Human Health Impacts

Release of cyanide and mercury into the environmentAcid mine drainageMining is a hazardous occupationBlack lung disease

Elemental Composition of the Earth’s Crust

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)