Geologic Resources and Earth’s Systems Types of Geologic Resources Resources and Reserves

1. Geologic Resources and Earth’s Systems
• Geologic resources - 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, hydrosphere,
and atmosphere when extracting and utilizing geologic resources
– Groundwater (hydrosphere) is a renewable geologic resource
• If it can’t be grown, it must be mined

2. Types of Geologic Resources
• Geologic resources are 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
– Non-metallic resources - sand and gravel,
limestone, building stone, salt, sulfur, gems,
gypsum, phosphates, groundwater, etc.

3. 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

4. Energy Resources - Coal
• Fossil fuels (oil, natural gas,
and coal) account for nearly
90% of U.S. energy
• 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

5. • Four varieties of coal
– Lignite (brown coal) is soft and crumbly
– Sub-bituminous and bituminous coal (soft coal)
• black and dusty
• burn with a smoky flame
• commonly strip-mined
– Anthracite (hard coal)
• 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. coal reserves could last for centuries
Energy Resources - Coal

6. Energy Resources
-Petroleum
• Petroleum - oil and natural gas
- occurs in underground pools
• 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

7. Structural Traps
for Gas and Oil
2300 m – 4600 m = Oil formation
4600+ m = Gas formation

8. Eroded anticline forms trap in Landers oil field in Wyoming.
Energy Resources - Petroleum

9. Other Oil Traps in Geological Structures

10. 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 through
wells drilled down into an oil trap within
a reservoir rock
• Negative environmental effects resulting
from oil recovery and transport include oil
spills, brine contamination of surface
water, and ground subsidence

11. Oil Peak, Oil Panic ?
(Study by Amos Nur - Stanford)
U.S., Canada, Japan, Germany, France, Italy, UK, are the biggest
consumers of oil reserves worldwide.

12. Oil Peaks – 1960's
In the 1850's oil mainly used
for kerosene lamps – remaining
was burned or disgarded.
Current oil production rates peaked
in 1960's but U.S. consumption rates
increase dramatically above this.
Don't panic!
-Try to conserve energy
-Seek alternative energy sources

13. At current rate of use, worldwide oil reserves should last 30-40 years,
and natural gas reserves somewhat longer (estimates from USGS)
Petroleum Reserves

14. Petroleum Reserves
• 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 black or brown shale with 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

15. Jobs and Salaries in Geology
Starting salaries for petroleum geologists with 0-2 yrs experience.
Mixture of B.S. and M.S. Degrees.

16. Jobs and Salaries in Geology
Geologists in Environmental (e.g. EPA, Geotechnical firms) and
Geologists in Government make $ 50 K – 75 K
Geology Ph.D. faculty starting salaries in 2007 ($70 K – 80 K)

17. Metals and Ores
• Metal ores - naturally occurring materials that can
be profitably mined
• Whether or not a mineral deposit is an ore
depends on chemical composition, the percent
extractable metal, and current market value of the
metal
• Metallic ore deposits originate from crystal
settling in igneous intrusions, hydrothermal fluids
cooling in pores and factures, chemical
precipitation in water, or sedimentation in
rivers (placers)

18. Mining and Metals
• Mining can be done at Earth’s surface
(strip mines, open-pit mines, and placer
mines) or underground
– Metals mined 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

19. Non-metallic Resources
• Non-metallic resources - not mined to extract a
metal or an energy source
– construction materials
• sand, gravel, limestone, and gypsum
– agriculture
• phosphate, nitrate and potassium compounds)
– industrial uses
• rock salt, sulfur, asbestos)
– gemstones
• diamonds, rubies, etc.
– household and business products
• glass sand, fluorite, diatomite, graphite)