Physical Geology, 15/e

Transcription

1 Lecture Outlines Physical Geology, 15/e Plummer, Carlson & Hammersley

2 Resources Physical Geology 15/e, Chapter 22

3 Types of Geologic Resources 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. Renewable Resources replenished by natural processes fast enough that people can use them continuously Nonrenewable Resources form very slowly and are extracted and used must faster than they can be renewed naturally.

4 Reserves and Resources Resource the total amount of any given geologic material of potential economic interest, discovered and undiscovered Reserves discovered deposits of geologic resources that can be extracted economically and legally under present conditions

5 Energy Resources Materials used to produce heat and electricity or as a fuel for transport US Fuel consumption = 19% of world energy use but have only 5% of world population Nonrenewable Energy Resources - (oil, natural gas, and coal) account for the majority of U.S. energy

6 Energy Resources Nonrenewable Energy Resources Coal a sedimentary rock that forms from the compaction of plant material that has not completely decayed Peat unconsolidated plant material Lignite (brown coal) is soft and crumbly Sub-bituminous and bituminous (soft coal) is black and dusty, burns with a smoky flame, is commonly strip mined Anthracite (hard coal), shiny and dust-free, burns with a smokeless flame, low level metamorphic rock 20% of energy supply in the USA USA has about 27% of world s coal reserves

7 Energy Resources Nonrenewable Energy Resources Petroleum and Natural Gas oil and natural gas, occurs in underground pools and requires: Source rock rich in organic matter Reservoir rock in which it can be stored and transmitted (e.g., sandstone) Structural (or Oil) trap, a set of conditions holding rock in reservoir rock and preventing migration Deep burial and sufficient time to cook the oil and gas out of the organic matter Oil traps

8 Energy Resources Nonrenewable Energy Resources Petroleum and Natural Gas Oil fields regions underlain by one or more oil pools 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 Oil reserves currently estimated to last another 50 years at current rates of use, worldwide

9 Energy Resources Nonrenewable Energy Resources Fracking horizontal drilling and hydraulic fracturing of low permeability shale zones has improved production Coal Bed Methane methane trapped within the coal Heavy Crude and Oil Sands - dense, viscous petroleum Oil Shale - black or brown shale with high solid organic matter content from which oil can be extracted by distillation Uranium uraninite (pitchblende) deposits used to power nuclear power generators Oil Shale

10 Energy Resources Renewable Energy Sources Geothermal Energy Heat energy from beneath the Earth s surface Solar Energy uses photovoltaic cells to generate electricity Wind Power use of wind turbines to generate electricity Hydroelectric power use of falling water to turn a turbine and generate electricity; provides about 2.8% of U.S. energy needs, is renewable and non-polluting

11 Energy Resources Renewable Energy Sources Tidal Power use of tidal changes to spin turbines and generate electricity Wave Power captures the energy of waves to generate electricity; mostly experimental technology Biofuels fuels derived from biologic (recently dead) matter such as ethanol and vegetable oil

12 Metallic Resources Metal ores naturally occurring metallic materials that can be profitably mined Ores Formed by Igneous Processes Crystal Settling - early forming minerals settle to the bottom of a cooling magma body Chromium of the Bushveldt and Stillwater complexes Hydrothermal Fluids most important source of metallic ore deposits other than iron and aluminum 1.)Contact metamorphic deposits 2.)Hydrothermal veins narrow ore bodies along joints and faults 3. Disseminated deposits 4.) Hot-spring deposits

13 Metallic Resources Ores Formed by Surface Processes Chemical Precipitation in Layers Banded Iron, Manganese and Copper Ores Placer Deposits concentration of mineral deposits by stream processes Gold, platinum, diamonds and other gemstones Concentration by Weathering Aluminum Ore - Bauxite Banded Iron Ore Deposits

14 Mining Mining can be done at Earth s surface or underground; metals mined include iron, copper, aluminum, lead, zinc, silver, gold and many others Strip Mining Open-pit Mining Placer Mining - Panning, Sluice boxes, Hydraulic Underground/bedrock mining Negative environmental effects of mining Tailings piles, surface scars, land subsidence, and acid mine drainage can be minimized

15 Nonmetallic Resources Nonmetallic resources not mined to extract a metal or an energy source Construction materials sand, gravel, limestone, and gypsum Fertilizers and Evaporites phosphate, nitrate, and potassium compounds; rock salt, gypsum, sulfur, asbestos Other Nonmetallics Gemstones diamonds, rubies, emeralds Asbestos, glass sand, fluorite, diatomite, graphite

16 Resources, The Environment, and Sustainability Demand for resources is likely going to increase as world population grows Extraction and transportation of resources has an enormous environmental impact Leaving enormous holes in the ground Removing whole mountain tops Massive Oil spills Release of Greenhouse gases The challenge is to find the right balance between mining, environmental protection and reducing consumption and increasing recycling

17 End of Chapter 22