Geology and Mineral Resources (Non-renewable) Chapter 14

Geology Study of the dynamic processes taking place on the earth’s surface and in its interior Three 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 mantle These 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 Tectonics Prior to 1900s scientists believed that Earth’s major features (oceans & continents) were fixed in place 1912 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 Atlantic Fossil evidence Theory of Plate Tectonics Earth’s lithosphere is divided into plates, most of which are in constant motion Tectonic cycle is the sum of the processes that build up and break down the lithosphere

Tectonic plates (2 types Oceanic & Continental) Plate Boundaries Convergent - collide Mountains Volcanoes Oceanic trenches Divergent - pull apart Oceanic ridges Transform – slide past each other Earthquakes plate tectonics plate boundary rap

Plate Boundaries

Volcanoes, Arcs, and Hotspots 85% of volcanoes occur along plate boundaries Hot spots form when plumes of molten material from the mantle reach the lithosphere When 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 Landslide Northridge Earthquake 1994 photos and data Tsunami Japan 2011

Rocks and Minerals Mineral: 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 crust Three major types of rock Sedimentary rock Igneous rock Metamorphic rock

Sedimentary Rock Made of sediments consisting of dead plant and animal remains and tiny particles of weathered and eroded rock Sandstone, shale, limestone, dolomite, coal Many fossils are found in this type of rock Formed by pressure

Igneous Rock Forms below the earth’s surface when magma rises from the mantle and then cools and hardens Make up the greatest percentage of the earth’s crust Frequently 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 SlateMarble

Weathering, Erosion, Rock Cycle Weathering 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 Erosion Material 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 Cycle Rock 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 uplifted Weathering and erosion Particles are then transformed into another type of rock Rock Cycle Animation

Mineral Resources – Nonrenewable A 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 products Considered nonrenewable b/c they take so long to form 2 types Metallic minerals (gold, silver, platinum, aluminum Nonmetallic minerals (sand/SiO 2, limestone/CaCO 3 ) 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 concentration Low 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 MetalGlobal Reserves Remaining (in years) US Reserves Remaining (in years) Iron12040 Aluminum3300 Copper6540 Lead2040 Zinc3025 Gold3020 Nickel750 Cobalt500 Manganese700 Chromium750

Types of Mining Subsurface 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 Mining Open 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 rock Contour strip mining – remove strips of soil in rock using the natural contour of the landscape Mountaintop removal – remove entire top of mountain using explosives Placer 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: Energy Water Environmental impacts include: Soil displacement and erosion Solid waste Greenhouse gases Human health hazards Acid mine drainage Dropping water tables

Impacts from mining, processing and use

Human Health Impacts Release of cyanide and mercury into the environment Acid mine drainage Mining is a hazardous occupation Black lung disease

Elemental Composition of the Earth’s Crust

Distribution of Minerals and Reserves Minerals are not distributed evenly throughout the earth’s land areas US, Canada, Russia, S. Africa, & Australia supply most of the world’s nonrenewable minerals Consumption differs greatly b/w LDCs and MDCs China Stockpiling 17 rare earth metals such as Tb, Ds needed for advanced technology industry United States Has stockpiles of Cr, Ti, Sn, Mn, Cr, Pt, and Co, b/c total of 20 elements must be imported, but reserves are dwindling

Depletion Time The amount of time it takes to use up 80% of the reserves of a mineral at a given rate of use Determined by two factors Actual/potential supply Rate of consumption 3 Scenarios No recycling or reuse Recycling, reuse, better technology Recycle, reuse, better technologies, new discoveries

Economics of Mining Mining becomes economically less feasible due to three factors: Increasing cost of mining due to quality of ore Shortages of water due to water table disturbances Environmental impacts New forms of mining or alternatives Biomining Ocean mining Find Substitutes for minerals

Mining Legislation Mining Law of 1872 (General Mining Law) Regulates the mining of silver, copper, and gold as well as fuels Companies can recover ores and fuels from federal lands Designed to encourage westward expansion, little to no environmental protections Surface Mining Control and Reclamation Act of 1977 Regulates surface mining of coal and the surface effects of subsurface coal mining Land must be disturbed as little as possible during the mining process

Treaties Antarctic 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 years Designated 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)