Geology and Nonrenewable Minerals

1. Geology and Nonrenewable Minerals Chapter 15

2. Environmental Effects of Gold Mining • Gold producers • South Africa • Australia • United States • Canada • Cyanide heap leaching • Extremely toxic to birds and mammals • 2000: Collapse of a dam retaining a cyanide leach pond Black Hills, S. Dakota

3. Earth’s Major Geological Processes and Hazards • Gigantic plates in the earth’s crust move very slowly atop the planet’s mantle, and wind and water move the matter from place to place across the earth’s surface. • Natural geological hazards such as earthquakes, tsunamis, volcanoes, and landslides can cause considerable damage.

4. The Earth Is a Dynamic Planet • What is geology? • Three major concentric zones of the earth • Core: solid inner part surrounded by a liquid core • Mantle: mostly solid rock • Including the asthenosphere: hot,partly melted rock that flows and can be deformed like plastic • Crust • Continental crust • Oceanic crust: 71% of crust

5. Major Features of the Earth’s Crust and Upper Mantle

6. The Earth beneath your feet is moving……. • Convection cells, orcurrents : move large volumes of rock and heat in loops within the mantle like gigantic conveyer belts • Tectonic Plates: dozen or so huge rigid plates move extremely slowly atop the denser mantle on hot, soft rock in the underlying asthenosphere • Lithosphere: continental and oceanic crust and the rigid, outermost part of the mantle

7. TheEarth’s Crust Is Made Up of a Mosaic of Huge Rigid Plates: Tectonic Plates

8. The Earth’s Major Tectonic Plates EURASIAN PLATE NORTH AMERICAN PLATE ANATOLIAN PLATE JUAN DE FUCA PLATE CHINA SUBPLATE CARIBBEAN PLATE PHILIPPINE PLATE ARABIAN PLATE AFRICAN PLATE INDIA PLATE PACIFIC PLATE PACIFIC PLATE COCOS PLATE SOUTH AMERICAN PLATE NAZCA PLATE AUSTRALIAN PLATE SOMALIAN SUBPLATE SCOTIA PLATE ANTARCTIC PLATE Divergent plate boundaries Transform faults Convergent plate boundaries Fig. 14-4, p. 347

9. The Earth beneath your feet is moving …. • Three types of boundaries between plates • Divergent plates –plates move apart • Magma – flows up through the resulting cracks • Oceanic ridge – some of which have higher peaks and deeper canyons than earth’s continents • Convergent plates – oceanic plate collides with a continental plate, • Subduction: the latter rides up over the denser oceanic plate and pushes it down into the mantle • Subduction zone: area where collision and subduction takes place • Trench : forms at the boundary between the 2 converging plates • Transform fault e.g. San Andreas fault: where plates slide and grind past one another along a fracture. Most located on the ocean floor

10. The San Andreas Fault as It Crosses Part of the Carrizo Plain in California, U.S.

11. Some Parts of the Earth’s Surface Build Up and Some Wear Down • Internal geologic processes • Generated by heat from the earth’s interior ,generally build up the earth’s surface in the form of continental and oceanic crust including mountains and volcanoes • External geologic processes • Weathering : driven directly or indirectly by energy from the sun(mostly in the form of flowing water and wind) • Physical, Chemical, and Biological : soil • Erosion • Wind • Flowing water • Human activities • Glaciers

12. Weathering: Biological, Chemical, and Physical Processes

13. Volcanoes Release Molten Rock from the Earth’s Interior • Volcano: magma reaches the earth’s surface through a.. • Fissure: central vent or a long crack • Magma • Lava: magma that reaches the earth’s surface. Debris ranging from large chunks of larva rock to glowing hot ash, liquid lava and gases such as water vapor, carbon dioxide and sulfur dioxide . Much of the world’s volcanic activity is concentrated along the boundaries of the earth’s tectonic plates • 1980: Eruption of Mount St. Helens • 1991: Eruption of Mount Pinatubo: cooled the earth’ average temperature for 15 months • Benefits of volcanic activity: highly fertile soil, creates outstanding landforms (Crater Lake in Oregon)

14. Creation of a Volcano

15. Earthquakes Are Geological Rock-and-Roll Events • Earthquake • Seismic waves • Focus • Epicenter • Magnitude • Amplitude • Richter scale • Insignificant: <4.0 • Minor: 4.0–4.9 • Damaging: 5.0–5.9 • Destructive: 6.0–6.9 • Major: 7.0–7.9 • Great: >8.0 Foreshocks andaftershocks Primary effects of earthquakes: shaking, permanent vertical or horizontal displacement of the ground

16. Major Features and Effects of an Earthquake

17. Areas of Greatest Earthquake Risk in the United States

18. Areas of Greatest Earthquake Risk in the World

19. Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis • Tsunami, tidal wave : generated when part of the ocean floor suddenly rises or drops. Usually occurs offshore in subduction zones. • Detection of tsunamis: by ocean buoys, pressure recorders on the ocean floor which measures changes in water pressure as the waves pass over it; data relayed via satellites tsunami warning systems • December 2004: Indian Ocean tsunami • Magnitude of 9.15 • Role of coral reefs and mangrove forests in reducing death toll

20. Formation of a Tsunami and Map of Affected Area of Dec 2004 Tsunami

21. Shore near Banda Aceh,Gleebruk in Indonesia before and after tsunami Before :June 23, 2004 After: December 28, 2004

22. Gravity and Earthquakes Can Cause Landslides • Mass wasting: detached or loose rock, soil and mud to slide down steep slopes near the shores of oceans or lakes • Slow movement • Fast movement • Rockslides • Avalanches • Mudslides : 1970 – Peru, buried the town of Yungay and killed 17,000 people • Effect of human activities on such geological events: • forest clearing, road building , crop growing, building houses

23. Earth’s Rocks are Recycled…….. • The three major types of rocks found in the earth’s crust—sedimentary, igneous, and metamorphic—are recycled very slowly by the process of erosion, melting, and metamorphism.

24. There Are Three Major Types of Rocks • Earth’s crust • Composed of minerals and rocks • Three broad classes of rocks, based on formation Sedimentary Igneous Sandstone Granite Shale Lava rock Dolomite Metamorphic Slate Anthracite Lignite Slate Bituminous coal Marble

25. The Earth’s Rocks Are Recycled Very Slowly • Rock cycle: the interaction of physical and chemical processes that change rocks from one type to another. Slowest of the earth’s cyclic processes

27. What Are Mineral Resources? • Naturally occurring materials in the earth’s crust that can be extracted and made into useful products in processes that provide economic benefits and jobs. • 100 minerals: • fossil fuels(coal) • metallic(aluminum, iron, copper) • non-metallic(sand, gravel, limestone, salt, precious gems) • Mineral deposit – area in which a particular mineral is concentrated. • Ore – metal-yielding material; contains 2 parts: the ore mineral (metal) and waste mineral material (gangue) • High-grade ore – large amount of desired metal • Low-grade ore – small amount of the desired resource

28. Removing Metals from Ores • Nonrenewable – takes so long to be produced • Ore extracted by mining • Ore mineral = desired metal • Gangue - waste material. Removing the gangue from the ores produces tailings. Particles of toxic metals blown by the wind or leached by rainfall can contaminate surface water and groundwater. • Smelting – heating ore in order to separate desired metals. Without proper equipment, releases sulfur dioxide and suspended particles, damage vegetation and acidify soils

29. Extracting, Processing, Using Nonrenewable Mineral and Energy Resources Life Cycle of a Metal Resource

30. Mineral Use Has Advantages and Disadvantages • Ads: Mine and convert minerals into useful products • Disads: uses enormous amounts of energy, disturbs land, erodes soil, produces solid waste, air and water pollution

31. Ways to Remove Mineral Deposits • Surface mining : shallow deposits removed • mechanized equipment strips away overburden(soil and rock overlay), discarded as waste called spoils • Used to extract 90% of the nonfuel mineral and rock resources and 6% of the coal Type of surface mining used depends on Resource Local topography • Subsurface mining • Deep deposits removed • Used to extract coal and metal ores

32. Types of Surface Mining • Open Pit Mining - machines dig hole and remove ore • Strip Mining - earth movers strip overburden and power shovels remove deposit • Contour Mining - mine coal on hilly terrain. Wall of dirt left in front of a highly erodible bank of soil and rock called highwall • Mountain Top Removal - Appalachian Mountains , draglines, explosives remove top of mountain to expose seams

33. Open-Pit Mine in Western Australia

34. Undisturbed land Overburden Highwall Coal seam Overburden Pit Bench Coal seam Contour Strip Mining in hilly areas Spoil banks Fig. 14-17, p. 357

35. Mountaintop Coal Mining in West Virginia, U.S.

36. Mining has Harmful Environmental Effects……. • Scarring and disruption of the land surface • E.g., spoils banks • Large amounts of solid waste (3/4th of all US solid waste) • Toxin-laced mining waste deposited in areas other than mining site . • Loss of rivers and streams – 1900 km have been buried • Subsidence - collapse of land

37. Harmful Environmental Effects Major pollution of water – Acid mine drainage Leaching of heavy metals Oil and chemical spills Highly toxic cyanide salts are used to extract gold from its ore; leave behind cyanide laden water Effect on aquatic life – pH change, 40% of all US watersheds contaminated Illegal Gold Mine

38. Environmental Effects of Gold Mining • Gold producers • South Africa • Australia • United States • Canada • Cyanide heap leaching • Extremely toxic to birds and mammals • 2000 - Collapse of a dam retaining a cyanide leach pond Black Hills, S. Dakota

39. Summitville Gold Mining Site in Colorado, U.S.

40. The U.S. General Mining Law of 1872 • Encouraged mineral exploration and mining of hard-rock minerals on U.S. public lands • Developed to encourage settling the West (1800s) • Until 1995, land could be bought for 1872 prices • Companies must pay for clean-up now

41. LEGISLATION

42. LEGISLATION (cont.)

43. POSSIBLE REMEDIES FOR MINIMIZING EFFECTS OF TOXINS • Buffer/neutralize with alkaline(basic) substances such as limestone (calcium carbonate), sodium hydroxide (NaOH), or ammonia. • Cover tailings to reduce contact with precipitation. • Sedimentation ponds/retention basins or ponds. • Bioremediation by sulfate-reducing bacteria.

44. Ecological Restoration of a Mining Site in New Jersey, U.S.

45. POSSIBLE STEPS TO RESTORING SURFACE-MINED LAND • Re-contouring/regrading land to its original topography. • Replacing and/or adding topsoil/nutrients as needed to improve soil quality or structure • Replanting • native vegetation • fast-growing species • early successional species • Monitor for 5 to 10 years

46. How Long Will Supplies of Nonrenewable Mineral Resources Last? • All mineral resources exist in finite amounts, and as we get closer to depleting any mineral resource, the environmental impacts of extracting it generally become more harmful. • Relatively abundant deposits of iron and aluminum (bauxite) • Scarce - manganese, chromium, cobalt, platinum • An increase in the price of a scarce mineral resource can lead to increased supplies and more efficient use of the mineral, but there are limits to this effect.

47. Uneven Distribution of Minerals • Most of the nonrenewable mineral resources supplied by • Canada • United States • Germany • Russia • South Africa - self sufficient in all key minerals, largest producer of gold, chromium and platinum • Australia 8% of world population, consume 75% of the world’s key metals China increasing consumption

48. Four Strategic Metal Resources…. • Manganese • Cobalt • Chromium • Platinum • US has little or no reserves of these metals which are essential for the country’s economy and military strength • May have to switch to “nano” materials

49. MINERAL PRODUCTION OF SOME NON-FUEL MINERAL RESOURCES

50. The Nanotechnology Revolution • Nanotechnology (tiny tech) - use carbon, oxygen and silicone atoms to create everything from medicines, solar cells to automobile bodies • Currently used in more than 400 items - odor eating socks, wrinkle –free clothes, cosmetics, sun screens • Nanoparticles • Are they safe? • Investigate potential ecological, economic, health, and societal risks • Develop guidelines for their use until more is known about them