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Unformatted text preview: 19: Earth’s Resources 2–
Photo: Chevron Corp. Coal, Ore: 1 Oil, Coal, Ores Energy resources
source of energy
150 years ago:
Q1. Which of the following supplied the most energy to the U.S. in 2000?
B. Natural gas
E. Wind & running water Coal, Ore: 2 Fig. 14.1 Hydrocarbons
Fossil fuels: oil, gas, and coal that are derived from organisms that lived long ago and thus store solar energy that reached Earth long ago
Hydrocarbons: molecules consisting of complex arrangements of carbon and hydrogen atoms
Crude oil: oil pumped out of the ground; it is refined (heated to separate hydrocarbons by density) to produce gasoline, kerosene, heating oil, lubricating oil; residue of refining process is used to make plastics and “tar” Coal, Ore: 3 Fig. 14.3 Recipe for oil & gas
1. Creation of source rocks: high organic productivity of
microscopic organisms (e.g., plankton, algae) plus high
preservation… Fig. 14.4 Coal, Ore: 4 Recipe for oil & gas
2. Formation of
oil & gas:
due to heat
Oil & gas window: typical range of temperature & depth at which hydrocarbons form
Coal, Ore: 5 Fig. 14.5 Recipe for oil & gas
3. Migration: low-density oil & gas rise (eventually
reaching the surface unless trapped)
reaching Fig. 14.4 Coal, Ore: 6 Recipe Animation 4. Trapping: oil & gas
accumulate in… Reservoir rock: rock with high porosity and permeability; oil can flow easily into it and can be pumped easily out of it
Seal rock: rock with low porosity and/or permeability that prevents oil and gas from rising to surface
Trap: geometry of reservoir and seal that allows significant volume of oil and gas to accumulate Fig. 14.8
Coal, Ore: 7 Recipe for oil & gas
Trap: geometry of reservoir and seal that allows significant volume of oil and gas to accumulate Photo: Skinner & Porter
Coal, Ore: 8 Types of traps
DOME (upsidedown bowl) 1. Salt structure
impermeable) Fig. 14.9
Coal, Ore: 9 Types of traps
Dome: upsidedown bowl. IDEAL TRAP Fig. 11.23 Sinclair dome, Wyoming. Photo: J. Shelton
Coal, Ore: 10
10 Types of traps
fault rock may
act as seal
unconformity) Coal, Ore: 11
11 Fig. 14.9 Exercises Cross section (side view); questions on next slide.
Coal, Ore: 12
Q2. At which location would you most likely find hydrocarbons?
A. 1 B. 2
C. 3 D. 14
Q3. At which of the following locations would you most likely find hydrocarbons?
A. 5, 6, 8, 10
B. 6, 7, 8, 9, 10
C. 6, 8, 10
D. 7 and 9 Assume that oil can migrate into all lithologies; faults and
salt are seals; all sandstones are potential reservoirs; all
shales are potential seals.
shales Q4. At which of the following locations would you most likely find hydrocarbons?
A. 15, 18, 21, 22, 23, 24, 25, 26
B. 15, 18, 21
C. 22, 24, 26
D. 23 and 25
Coal, Ore: 13
13 Why does (did) does oil cost so much?
Fears over supply shortages; political tensions; strong
demand (China, India), weakening demand (recession),
weakening dollar / economic recovery Coal, Ore: 14
14 Are we running
out of oil? Nonrenewable resource: resource that cannot be replenished on the time scale of a few years (all fossil fuels, most mineral resources, some aquifers)
Renewable resource: resource that can be replenished on the time scale of a few years (solar, wind, geothermal, tidal, hydropower)
Q5. The world’s supply of oil is likely to be depleted in about _______ years.
D. 1 million Coal, Ore: 15
15 Fig. 14.31 Review Questions
191. What type of rock is most likely to contain oil, natural gas, and coal?
192. Chemically, oil and gas are both ____________.
A. pure forms of carbon
D. carbonate minerals
193. Most of the hydrocarbons within oil and natural gas are derived from the breakdown of organic matter from onceliving ____________.
A. dinosaurs B. plankton
C. terrestrial (land) plants
194. In order to produce a commercially viable oil deposit, there must be a source rock, a reservoir rock, a seal rock, and a ____________.
A. large fracture connecting the reservoir rock to the surface of the Earth, so the oil
can move freely toward the surface
B. filter rock—a rock of intermediate permeability located between the source and
reservoir rocks to remove impurities
C. heater rock—an intrusive igneous rock beneath the source rock to heat the oil
and give it buoyancy
D. trap—a geologic configuration that forces oil to pool up and denies it passage to
Coal, Ore: 16
16 Review Questions
195. A black, organicrich shale could likely serve as either of which two necessary types of rocks within oil fields?
A. source rock or seal rock
B. reservoir rock or seal rock
C. source rock or reservoir rock
196. Which of the following is a good reservoir rock for hydrocarbons?
A. rock salt
197. A permeable and porous rock, regardless of lithology, is a good candidate to serve as a ____________ in an oil producing scenario.
A. reservoir rock
B. seal rock
C. source rock
198. Shale, salt, and unfractured crystalline rocks are all good candidates to serve as ____________ within an oil field.
A. a reservoir rock
B. a seal rock
C. a source rock
D. either a source or a reservoir rock
199. The best type of structure for trapping hydrocarbons is a(n):
1910. Which of the following is NOT an important type of oil trap?
A. salt dome B. syncline
C. stratigraphic D. anticline
Coal, Ore: 17
17 Energy resources: coal
Coal: black, brittle sedimentary rock that burns; it consists mostly of carbon derived from terrestrial (land) plants Fig. 14.14
Coal, Ore: 18
18 Energy resources: coal
preservation: Site of
accumulation: Fig. 14.18 Coal, Ore: 19
19 Coal: progressive transformation
• Original plant
to form peat.
• Peat is
(brown coal) and
coal as a result
of burial. Coal, Ore: 20
20 Fig. 14.19 Coal: progressive transformation
Metamorphism of coal produces anthracite. Fig. 14.19
Increasing rank (energy content):
Coal, Ore: 21
Most extensive coal deposits in Late Carboniferous
Permian (320245 Ma) North
equator… Fig. 13.22
Coal, Ore: 22
22 South Pole Fig. 14.16 Review Questions
1911. A. True / B. False: For hydrocarbons and coal deposits to form, organic matter must accumulate in a highoxygen environment.
1912. Coal is the altered remains of ancient ____________.
A. dinosaurs B. plankton
C. terrestrial plants D. mammals 1913. Most of the world’s coal was deposited in swamps during the _________.
A. Cretaceous B. Ordovician
1914. Which sequence of coal ranks is ordered from lowest to highest?
A. anthracite, bituminous, lignite
B. lignite, bituminous, anthracite
C. bituminous, lignite, anthracite
D. bituminous, anthracite, lignite
1915. A. True / B. False: Anthracite is associated with metamorphic rocks.
1916. A. True / B. False: During the Carboniferous period, North America was located near the south pole. Coal, Ore: 23
23 Mineral Resources
Ore minerals: minerals that contain metal in high concentrations and in a form that can be easily extracted.
Photo: C. Clark Coal, Ore: 24
24 Mineral Resources
Ores (rocks containing ore minerals) are produced when
geologic processes concentrate metal-bearing minerals in
abundances higher than normal. Fig. 15.5b Coal, Ore: 25
25 Ore-forming processes
Magmatic: earlyformed, dense,
accumulate at the
bottom of a
magma chamber Coal, Ore: 26
26 Fig. 15.7 Ore-forming processes
or through the
rocks or fractures
igneous intrusion Fig. 15.8
Coal, Ore: 27
27 Ore-forming processes
Hydrothermal deposits Black smokers along seafloor
spreading centers Photo: D.B. Foster
Coal, Ore: 28
28 Fig. 15.10 Ore-forming
Fig. 15.11 Secondary enrichment:
dissolves minerals out of
an low-grade ore body
and precipitates them in
less oxygen-rich water
below the water table,
forming a high-grade ore
Coal, Ore: 29
29 Ore-forming processes
Banded-iron formations: iron-oxide-rich deposits that formed
between 2 and 2.5 billion years ago, when rising oxygen levels
(produced by photosynthesis) in the atmosphere and oceans
caused previously dissolved iron to precipitate (come out of
solution) Fig. 15.12
Coal, Ore: 30
30 Ore-forming processes
metal grains in
that develop when
metals erode and
create a mixture of
clasts and metal
carries away the
leaving behind the
metals (like gold,
with a density of
19 g/cm3). Fig. 15.14
Coal, Ore: 31
31 Review Questions
1917. In magma chambers, ore minerals typically ______.
A. rise to the top
B. sink to the bottom
C. mix well with the rest of the magma
D. solidify and reside in the middle of the magma
1918. A. True / B. False: Magmatic ore deposits are the last minerals to crystallize in a magma chamber.
1919. Hydrothermal ore deposits are common at ___ plate boundaries. [Hint: Which plate boundary is associated with black smokers and other hydrothermal vents?] A. conservative
1920. Which ore minerals are commonly found in ancient sedimentary deposits that are 2 billion years old?
A. copper sulfides
B. aluminum oxides
C. iron oxides D. copper oxide 1921. A. True / B. False: Bandediron formations are forming in the oceans today.
1922. A. True / B. False: Placer deposits are common on the inside bends of meandering rivers, where the flow velocity is lower than elsewhere in the channel.
Coal, Ore: 32
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- Fall '11