1. Lecture Outlines Physical Geology, 10/e
Plummer, McGeary & Carlson

2. Geologic Resources Physical Geology 10/e, Chapter 21
Steve Kadel, Glendale Community College

3. Geologic Resources and Earth’s Systems
Geologic resources are valuable materials of geologic origin that can be extracted from the Earth
Many geologic resources originate in the hydrosphere
Petroleum and coal come from organisms that lived and died in water
Halite (salt) and other evaporite minerals come from dry lake beds
Weathering interactions between geosphere, atmosphere and hydrosphere produce metal oxide ores
Humans (biosphere) interact directly with the geosphere, the hydrosphere, and the atmosphere when extracting and utilizing resources
Even water, when found beneath the Earth’s surface, is a geologic resource (renewable)

4. Types of Geologic Resources
Geologic resources can be grouped into three major categories:
Energy resources - petroleum (oil and natural gas), coal, uranium, geothermal resources
Metals - iron, copper, aluminum, lead, zinc, gold, silver, platinum, etc.
Non-metallic resources - sand and gravel, limestone, building stone, salt, sulfur, gems, gypsum, phosphates, etc.
Groundwater is included in this category

5. Resources and Reserves
Resources - the total amount of a valuable geologic material in all deposits, discovered and undiscovered
Reserves - discovered deposits of geologic resources that can be extracted economically and legally under present conditions
The short-term supply of a geologic materials

6. Energy Resources
Fossil fuels (oil, natural gas, and coal) account for nearly 90% of U.S. energy
Petroleum - oil and natural gas - occurs in oil pools (valuable underground accumulations)
Occurrence of oil pools requires:
A source rock (rich in organic matter)
A reservoir rock in which it can be stored and transmitted (e.g., sandstone)
An oil trap (set of conditions holding rock in reservoir rock and preventing migration)
Deep enough burial (and sufficient time) to “cook” the oil and gas out of the organic matter
Oil traps

7. Petroleum Recovery
Oil fields are regions underlain by one or more oil pools
Largest in U.S. are in Texas and Alaska
Oil and natural gas are removed from the ground through wells that are drilled down into a reservoir rock within a trap
Negative environmental effects resulting directly or indirectly from oil recovery and transport include oil spills, brine contamination of surface water, and ground subsidence

8. Petroleum Reserves
At current rate of use, worldwide oil reserves should last about 35 to 40 years, and natural gas reserves somewhat longer
As petroleum prices rise, alternate petroleum sources, such as heavy crude, oil shale and oil sand, will be increasingly exploited
Heavy crude is dense, viscous petroleum
Oil shale is a black or brown shale with a high solid organic matter content from which oil can be extracted by distillation
Oil sands (or tar sands) are asphalt-cemented sand or sandstone deposits

9. Coal
Coal is a sedimentary rock that forms from the compaction of plant material that has not completely decayed
Forms from shallow burial and compaction of peat
Occurs in beds ranging from a few centimeters to thirty meters thick
Primary use in U.S. is for generating electricity

10. Coal
Four varieties of coal are lignite, sub-bituminous, bituminous, and anthracite
Lignite (brown coal) is soft and crumbly
Sub-bituminous and bituminous coal (soft coal) are black and dusty; burn with a smoky flame
Often strip-mined
Anthracite (hard coal) is shiny and dust-free; burns with a smokeless flame; low-level metamorphic rock
Burning of high-sulfur coal can produce acid rain; strip mines can scar landscape
U.S. has coal reserves than could last for centuries

11. Other Energy Resources
The metal uranium is used to power nuclear power generators
Typically found in association with organic matter in sedimentary rocks
Accounts for 10% of U.S. energy production
Leaves radioactive waste as by-product
Hydroelectric power provides about 4% of the energy needs of the United States
Renewable and non-polluting
Geothermal power provides about 0.2% of U.S. energy needs, but could be greatly expanded with new techniques
Other renewable and non-polluting sources include wave/current power, solar power, wind power, and hydrogen fuel cells
As fossil fuel supplies dwindle, these sources will become more important

12. Metals and Ores
Metal ores are naturally occurring materials that can be profitably mined
Whether or not a mineral deposit is considered an ore depends on its chemical composition, percentage of extractable metal, and the current market value of the metal
Metallic ore deposits can originate by crystal settling in igneous intrusions, from hydrothermal fluids cooling in pores and factures, by chemical precipitation in surface or groundwater, or by river sedimentation (placers)

13. Mining and Metals
Mining can be carried out on Earth’s surface (strip mines, open-pit mines, and placer mines) or underground
Metals mined using these techniques include iron, copper, aluminum, lead, zinc, silver, gold and many others
With care, negative environmental effects of mining, including unsightly tailings piles, surface scars, land subsidence, and acid mine drainage can be minimized

14. Non-metallic Resources
Non-metallic resources are those that are not mined to extract a metal or as a source of energy
Such resources are used for construction materials (sand, gravel, limestone, and gypsum), agriculture (phosphate, nitrate and potassium compounds), industrial uses (rock salt, sulfur, asbestos), gemstones (diamonds, rubies), and for manufacture of household and business products (glass sand, fluorite, diatomite, graphite)
If it can’t be grown, it must be mined

15. End of Chapter 21