19_oil_coal_ore_09_post

19_oil_coal_ore_09_post - 19: Earth’s Resources 2–...

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Unformatted text preview: 19: Earth’s Resources 2– Photo: Chevron Corp. Coal, Ore: 1 Oil, Coal, Ores Energy resources Most common Most source of energy 150 years ago: wood wood Q1. Which of the following supplied the most energy to the U.S. in 2000? A. Coal B. Natural gas C. Nuclear D. Oil 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 1. microscopic organisms (e.g., plankton, algae) plus high preservation… preservation… Fig. 14.4 Coal, Ore: 4 Recipe for oil & gas 2. Formation of 2. oil & gas: organic chemicals transformed to hydrocarbons due to heat resulting from… from… 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 3. reaching the surface unless trapped) reaching Fig. 14.4 Coal, Ore: 6 Recipe Animation 4. Trapping: oil & gas 4. 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 1. Anticline (upfold) or DOME (upsidedown bowl) 1. Salt structure (salt is 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 3. Fault: juxtaposes reservoir against seal; fault rock may act as seal 4. Stratigraphic (angular unconformity) Coal, Ore: 11 11 Fig. 14.9 Exercises Cross section (side view); questions on next slide. Coal, Ore: 12 12 Exercises 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 Assume 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. A. 10 B. 100 C. 1000 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? A. igneous B. sedimentary C. metamorphic 19­2. Chemically, oil and gas are both ____________. A. pure forms of carbon B. carbohydrates C. hydrocarbons 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 D. mammals 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 the surface 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 B. sandstone C. shale 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): A. anticline B. basin C. dome D. syncline 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 Fig. 14.16 Conditions for Conditions preservation: preservation: Site of Site accumulation: accumulation: Fig. 14.18 Coal, Ore: 19 19 Coal: progressive transformation • Original plant material is compacted and partially decays to form peat. • Peat is transformed first into lignite (brown coal) and then bituminous 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): Peat-->Lignite-->Bituminous-->Anthracite Coal, Ore: 21 21 Conditions favoring coal formation Most extensive coal deposits in Late Carboniferous­ Permian (320­245 Ma) North America located on 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 C. Carboniferous D. Jurassic 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, metal-bearing minerals (typically sulfides) accumulate at the bottom of a magma chamber Coal, Ore: 26 26 Fig. 15.7 Ore-forming processes Hydrothermal: metals precipitated from hot-water solutions circulating through magma or through the rocks or fractures in rock surrounding an 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 processes Fig. 15.11 Secondary enrichment: oxygen-rich water 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 body 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 Placer: concentration of metal grains in stream sediment that develop when rocks containing metals erode and create a mixture of clasts and metal fragments; the moving water carries away the less-dense grains, leaving behind the higher-density 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 B. convergent C. divergent 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 32 ...
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