Geology and Nonrenewable Mineral Resources G Tyler Millers

Geology and Nonrenewable Mineral Resources G. Tyler Miller’s Living in the Environment 14 th Edition Chapter 16

Key Concepts Ø Major geologic processes Ø Earthquakes and volcanoes Ø Minerals, rocks, and the rock cycle Ø Finding and extracting mineral resources Ø Non-renewable mineral resources

Geologic Processes: Structure of the Earth Geology is the study of dynamic processes occurring on the earth’s surface and in its interior. The surface of the earth is composed of a series of gigantic plates that move very slowly across the earth’s surface. The surface features of the earth change due to the effects of water and earth movements. Earthquakes and volcanic action are violent and disruptive actions of the earth. Three major zones of the earth are the core, mantle, and crust. The crust is soil and rock that floats on a mantle of partly melted and solid rock. The core is intensely hot. It has a solid inner part surrounded by a liquid core of molten or semisolid material. The mantle is a thick, solid zone. It is mostly solid rock, but an area called the asthenosphere is very hot, partly melted rock about the consistency of soft plastic. The crust is thin and is divided into the continental crust and the oceanic crust.

Features of the Crust and Upper Mantle There are three types of boundaries for lithospheric plates. The boundaries are divergent plate boundaries, where plates move apart in opposite directions, and convergent plate boundaries, where plates are pushed together by internal forces and one plate rides up over the other. A trench generally occurs at the subduction zone. The third type of boundary is a transform fault and occurs where plates slide/grind past one another.

The Dynamic Earth – Internal Processes Geologic changes from the earth’s interior generally build up the earth’s surface. Heat and gravity play a role in these processes. Heat from the core causes much of the mantle to deform and flow slowly like heated plastic. Two kinds of movement seem to occur in the mantle. Convection currents move large volumes of rock and heat in loops within the mantle. Mantle plumes flow slowly upward, and when it reaches the top of the plume, it radiates out like the top of an open umbrella.

Earth’s Major Tectonic Plates Measurement of the magnitude of an earthquake is done using the Richter scale, where each higher number is 10 times greater than the next lower number. Insignificant is less than 4. 0 on the Richter scale, minor is 4. 0– 4. 9, damaging is 5. 0– 5. 9, destructive is 6. 0 – 6. 9, major is 7. 0– 7. 9, and great is over 8. 0. Plate Movement Earthquakes An earthquake occurs at a fracture line or causes a fracture and shift in the earth’s crust.

Earthquakes Foreshocks may occur prior to the main shock and aftershocks occur up to several months after the main shock. Primary effects include shaking and temporary to permanent displacement of the ground. Secondary effects include rockslides, fires, and flooding due to subsidence of the land. Examination of an area for faults prior to building can help save lives and destruction of property

Expected Earthquake Damage Fig. 16 -7 p. 337 Seismic Waves P – primary (compression waves) S – Secondary wave (sheer waves) Surface Waves Impact of waves Building Collapse retrofit Expected Earthquakes

Natural Hazards: Volcanic Eruptions An active volcano releases magma onto the earth’s surface. This release may be violent or quiet. 1. Volcanic activity is generally concentrated in the same areas as seismic activity. 2. Ash and gases may be ejected along with magma. 3. Gases such as sulfur dioxide may remain in the atmosphere and cause acid rain. 4. Particulate matter may remain in the atmosphere for up to 3 years and cause cooling of the atmosphere. 5. Fertile soils are produced from the weathering of lava flows. 6. Scientists are studying phenomena that precede an eruption to better predict their occurrence.

External Earth Processes Ø Erosion Ø Mechanical (Physical) weathering Ø Frost wedging Ø Chemical weathering Ø Biological weathering Minerals and Rocks Ø Mineral (diamond, quartz) Rock Types Ø Igneous (granite, basalt) Ø Sedimentary (limestone, sandstone) Ø Metamorphic (marble, slate) Breaker and whoosh

Transport Erosion Deposition Rock Cycle Weathering Igneous Rock Granite, Pumice, Basalt Sedimentary Rock Shale, Sandstone, Limestone Heat, Pressure Heat, Metamorphic Rock Pressure Slate, Quartzite, Marble Magma (Molten Rock) Fig. 16 -9 p. 339

Nonrenewable Mineral Resources Ø Metallic Silver, Copper, Aluminum, Gold Ø Non-metallic Phosphates -Fertilizers Ø Energy resources Coal, Oil and Natural Gas Ø Ores Extracting Nonrenewable Mineral Resources: Ø Open-pit (surface mining) Ø Dredging (surface mining) Ø Area strip (surface mining) Ø Contour strip (surface mining) Ø Room-and-pillar (subsurface mining) Ø Longwall (subsurface mining)

Nonrenewable Mineral Resources: Categories Ø Ø Identified Undiscovered Reserves Other Finding Nonrenewable Mineral Resources Ø Ø Ø Satellite and air imagery Radiation detectors Magnetometers Gravity differences Seismic surveys Chemical analyses Processing Mineral Resources Ø Ø Ore mineral Gangue Tailings Smelting Fig. 16 -10 p. 340

Smelting Separation of ore from gangue Melting metal Metal ore Conversion to product Recycling Discarding of product Surface mining Scattered in environment

Mining Laws Mining Act of 1872 What is the impact of the 1872 Law? The Hardrock Mining and Reclamation Act of 2009 (S. 796) Surface Mining Control and Reclamation Act Ø Established 1977 Ø Mine lands must be restored to pre-mining conditions Ø Taxes on mining companies to restore pre-1977 sites Ø Limited success

Environmental Effects of Mining Mineral Resources Fig. 16 -14 p. 344 Ø Disruption of land surface Ø Subsidence Ø Erosion of solid mining waste Ø Acid mine drainage Ø Air pollution Ø Storage and leakage of liquid mining waste

More Environmental Impacts of Nonrenewable Mineral Resources

Supplies of Mineral Resources Ø Economic depletion Ø Depletion time Ø Foreign sources Ø Environmental concerns Ø Economics Ø New technologies Ø Mining the ocean Ø Finding substitutes Fig. 16 -16 p. 346