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Geology and Non-renewable Mineral Resources
Ch. 14
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Core Case Study: The Real Cost of Gold
Gold (Au): metallic mineral resource Extraction process requires spraying of toxic cyanide salts Drains into collection ponds, then leaches into ground water Core Case Study: The Real Cost of Gold
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The Earth Is a Dynamic Planet
What is geology? Dynamic processes taking place on earth’s surface and in earth’s interior Three major concentric zones of the earth Core Mantle Asthenosphere-partly melted rock Lithosphere-rigid outermost layer of mantle Crust Continental crust Oceanic crust: 71% of crust The Earth Is a Dynamic Planet
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The Earth Beneath Your Feet Is Moving (1)
Convection cells, or currents Move large volumes of rock and heat Like huge conveyer belts Tectonic Plates- moving rigid plates atop the asthenosphere Very slow moving Part of the lithosphere The Earth Beneath Your Feet Is Moving (1)
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The Earth Beneath Your Feet Is Moving (2)
Three types of boundaries between plates Divergent boundaries- plates move apart Oceanic ridge- 2 oceanic plates move apart Convergent boundaries-plates move toward each other Mountain formation- continental plates collide Subduction- oceanic plate and continental plate collide Trench- 2 oceanic plates collide Normally forms at boundary between 2 plates Transform boundaries: San Andreas fault Slide past and grind one another The Earth Beneath Your Feet Is Moving (2)
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The Earth’s Crust Is Made Up of a Mosaic of Huge Rigid Plates: Tectonic Plates
Figure 14.3: The earth’s crust is made up of a mosaic of huge rigid plates, called tectonic plates, which move very slowly across the asthenosphere in response to forces in the mantle. See an animation based on this figure at CengageNOW. Fig. 14-3, p. 348
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Divergent plate boundaries Convergent plate boundaries
EURASIAN PLATE NORTH AMERICAN PLATE ANATOLIAN PLATE CHINA SUBPLATE JUAN DE FUCA PLATE 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 Figure 14.4: This map shows the earth’s major tectonic plates. See an animation based on this figure at CengageNOW. Question: Which plate are you riding on? SCOTIA PLATE ANTARCTIC PLATE Divergent plate boundaries Convergent plate boundaries Transform faults Fig. 14-4, p. 349
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The San Andreas Fault as It Crosses Part of the Carrizo Plain in California, U.S.
Figure 14.5: This is the San Andreas Fault as it crosses part of the Carrizo plain between San Francisco and Los Angeles, California (USA). This fault, which runs almost the full length of California, is responsible for earthquakes of various magnitudes. Question: Is there a transform fault near where you live? Fig. 14-5, p. 350
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Some Parts of the Earth’s Surface Build Up and Some Wear Down
Internal geologic processes Generally build up the earth’s surface External geologic processes Wear down earth’s surface Weathering Physical, chemical, and biological Erosion Wind Flowing water Human activities Glaciers Some Parts of the Earth’s Surface Build Up and Some Wear Down
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Volcanoes Release Molten Rock from the Earth’s Interior
Volcano- magma reaches earth’s surface through central vent or fissure Lava- magma that reaches earth’s surface Eruption can have a cooling effect ejected material (ash, soot, particulate) reduces incoming solar radiation 1991: Eruption of Mount Pinatubo (Philippines) 2nd largest eruption in 20th century Killed 100’s of people Benefits of volcanic activity Mountain formation (aesthetic, habitat diversity) Weathering of lava contributes to soil fertility Volcanoes Release Molten Rock from the Earth’s Interior
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Extinct volcanoes Eruption cloud Ash Acid rain Ash flow Lava flow
Mud flow Central vent Landslide Magma conduit Figure 14.6: A volcano is created when magma in the partially molten asthenosphere rises in a plume through the lithosphere to erupt on the surface as lava (photo inset), which builds into a cone. Sometimes, internal pressure is high enough to cause lava, ash, and gases to be ejected into the atmosphere or to flow over land, causing considerable damage. Some volcanoes that have erupted and then become inactive have formed islands or chains of islands. Solid lithosphere Magma reservoir Partially molten asthenosphere Upwelling magma Fig. 14-6b, p. 351
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Earthquakes Are Geological Rock-and-Roll Events (1)
Earthquake-internal geological process Formation of transform fault causes abrupt movement on an existing fault Seismic waves- accumulated vibrational energy Most occur on boundaries of tectonic plates Focus Epicenter Seismograph & the Richter Scale Earthquakes Are Geological Rock-and-Roll Events (1)
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Earthquakes Are Geological Rock-and-Roll Events (2)
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 Largest recorded earthquake: 9.5 in Chile in 1960 Earthquakes Are Geological Rock-and-Roll Events (2)
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Liquefaction of recent sediments causes buildings to sink
Two adjoining plates move laterally along the fault line Earth movements cause flooding in low-lying areas Landslides may occur on hilly ground Figure 14.7: An earthquake (left), one of nature’s most powerful events, has certain major features and effects. In 2010, a major 7.0 earthquake in Haiti (right) killed at least 72,000 people and devastated this already very poor country. Shock waves Focus Epicenter Fig. 14-7a, p. 351
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Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis
Parts of ocean floor rises or drops Tsunami, tidal wave Travels several hundred miles per hour Detection of tsunamis Buoys in open ocean December 2004: Indian Ocean tsunami Magnitude 9.15 and 31-meter waves at shore Role of coral reefs and mangrove forests in reducing death toll Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis
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Undersea thrust fault Upward wave Bangladesh India Myanmar Thailand
Earthquake in seafloor swiftly pushes water upwards, and starts a series of waves Waves move rapidly in deep ocean reaching speeds of up to 890 kilometers per hour. As the waves near land they slow to about 45 kilometers per hour but are squeezed upwards and increased in height. Waves head inland causing damage in their path. Undersea thrust fault Upward wave Bangladesh India Myanmar Figure 14.8: This diagram illustrates how a tsunami forms. The map shows the area affected by a large tsunami in December 2004. Thailand Sri Lanka Malaysia Earthquake Sumatra Indonesia December 26, 2004, tsunami Fig. 14-8, p. 352
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The Earth’s Rocks Are Recycled Very Slowly
Rock cycle Slowest of the earth’s cyclic processes The Earth’s Rocks Are Recycled Very Slowly
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Igneous rock Granite, pumice, basalt
Erosion Transportation Weathering Deposition Igneous rock Granite, pumice, basalt Sedimentary rock Sandstone, limestone Heat, pressure Cooling Heat, pressure, stress Figure 14.10: Natural capital. The rock cycle is the slowest of the earth’s cyclic processes. Rocks are recycled over millions of years by three processes: erosion, melting, and metamorphism, which produce sedimentary, igneous, and metamorphic rocks. Rock from any of these classes can be converted to rock of either of the other two classes or can be recycled within its own class (Concept 14-2). Question: What are three ways in which the rock cycle benefits your lifestyle? Magma (molten rock) Melting Metamorphic rock Slate, marble, gneiss, quartzite Fig , p. 354
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Mineral Resources are NON-Renewable
Can be extracted from earth’s crust and processed into raw materials and products at an affordable cost Metallic minerals Nonmetallic minerals Ore Contains profitable concentration of a mineral High-grade ore Low-grade ore 2 types of Minerals Non-metallic (ex: sand, gravel, limestone, phosphate salts) Metallic: (ex: gold, aluminum, copper) Mineral Resources are NON-Renewable
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The Life Cycle of a Metal Resource
Figure 14.11: Each metal resource that we use has a life cycle. Each step in this process uses large amounts of energy and water, and produces some pollution and waste. The Life Cycle of a Metal Resource Fig , p. 355
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Removing Mineral Deposits
Surface Mining Shallow minerals Requires: Remove vegetation Overburden: remove soil/rock Waste piles called spoils Types of Surface Mining Open-Pit Mining Strip Mining Mountain-Top Removal Subsurface mining Removal method dependent on type of resource and local topography Removing Mineral Deposits
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Open-Pit Mining Heavy machinery used to dig large holes Removal of
metals (iron, copper, gold) non-metals (limestone, marble) Open-Pit Mining
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Useful for mineral deposits lying in large horizontal beds close to earths surface
Area Strip mining: Flat terrains Contour Strip Mining: Mostly for coal reserved in hilly/mountainous terrain Often leaves a high wall Strip Mining
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Commonly used method in U.S. Appalachian mountain range
Utilizes Explosives Earth movers Power shovels draglines Mountaintop Removal
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Subsurface Mining Needed for deeper deposits
Extracted from tunnels and shafts Common for coal and metal ores Miners dig deep vertical trenches Blast open subsurface tunnels Machinery for removal and transport Subsurface Mining
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Environmental and Health Impacts of Mining
Land surface scarring Increased susceptibility of erosion Slow vegetation regrowth Generation of large amounts of waste rock and dirt May result in stream burial (increase floods), produce waste water/toxic sludge Land Subsidence Air pollution SPM generation from smelting and explosion Smelting also may release toxic gaseous pollutants Environmental and Health Impacts of Mining
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Research Assignment I. Diagram locating the different tectonic plates
Include the name & what type of plate it is Label the boundary types Include 4 examples of geological formations (ex. The San Andreas fault) II. Mining Describe the different mining methods and give examples of areas of specific reserves Identify 3 different chemicals used to extract minerals from their ore Specify which mineral a specific chemical is used for Research Assignment
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