Week 12: Energy & Mineral Resources Flashcards
What are Mineral Resources?
Concentration of material of economic interest in or on the earth’s crust
(emphasis on concentration)
What are Ore Reserves?
Parts of a Mineral Resource that can at present be economically mined
What are Fossil Fuels?
Any organically derived sedimentary rock, or a product from an organic sedimentary rock that can be burned for fuel
(e.g. petroleum, natural gas, coal)
Which country has the largest coal reserve?
The US
How much of global electricity does coal produce?
1/3
What are the two stages of fossil fuel formation?
1) Decay of organic matter by biochemical alteration near the surface
2) Dewatering of sedimentary material and CRACKING of the organic material due to burial and increase in pressure and temperature
What is Cracking of organic material?
Large complex hydrocarbon molecules are broken down into smaller molecules (like methane)
Coal is derived from what material?
terrestrial plant material
(e.g. peat bogs, mangrove swamps)
What happens to coal with increase of temperature and pressure?
Becomes anthracite (low grade metamorphic) - burns better
How does Peat become coal?
Major chemcial and physical changes due to increase in Pressure and Temperature
What did Anita Harris do?
She found a correlation between the colour of conondonts and grade of the coal, and how that determined the temperature of the coal
What are the three grades of coal that form?
Lignite
Bituminous coal
Anthracite coal
What do Petroleum and Natural Gas form from?
Marine organisms such as phyto plankton and bacteria
What kind of hydrocarbons is Petroleum made of?
Naturally occurring liquid hydrocarbons
What kind of hydrocarbons is Natural Gas made of?
Naturally occurring gaseous hydrocarbons
What are the 4 steps in the formation of Petroleum and Natural Gas?
1) Formation of the source rock
2) Formation of hydrocarbon molecules
3) Migration of the hydrocarbon molecules away from the source rock
4) Trapping of the molecules in a suitable reservoir rock
What are some active sedimentary basins for Petroleum and Natural Gas?
- Gulf of Mexico
- Mediterranean
-Black Sea
How do hydrocarbons move away from the source rock?
Because they’re lighter than water and will therefore rise up through porous rock
Describe a good reservoir rock?
Permeable so that its fluids can be removed from them
What is a trap?
A zone that confines the migration of hydrocarbons
What are stratigraphic traps?
Poruous and permeable rocks being sealed off by an overlying impermeable bed.
Spreads out laterally with regional seal and eventually can surface (Alberta oilsands)
What are Structural Traps?
Anticlinal domes, flanks of a salt dome, normal and thrust faults
-> oil and gas are trapped by these formations
What is a Mineral Deposit?
A naturally occurring anomalous concentration of minerals that may be extracted at a profit. (don’t have to be)
What is an Ore Deposit?
A naturally occurring anomalous concentration of minerals in amounts sufficient to permit economic and profitable recovery
List examples of precious and base metal deposits
gold, silver, platinum, copper
List examples of ferrous metal deposits
iron, nickel, molybdenum
List examples of mineral fuels
coal, uranium
What does Concentration mean (in terms of Mineral Resources)?
Concentration = mass of element (mineral) / mass of rock body containing it
What is the Economic concentration (grade factor)
concentration that is required for any
element/mineral to be economically mined
What is the Economic Concentration factor
grade factor divided by the average
concentrations of the element in continental crust
How do elements or minerals become concentrated above
average crustal concentrations?
- Hydrothermal processes
- Magmatic processes
- Sedimentary processes
- Weathering processes
- Metamorphic processes
What are hydrothermal deposits?
Minerals from magmatic intrustion are surrounded by hot water which ascends through fractures in the rock (forming veins).
Precipitation due to:
1) change in pressure
2) change in temperature
3) change in the fluid composition
What are Veins?
Fractures that are partially or completely filled with
minerals that precipitated out of solutions.
Fluids move from high pressure to low
pressure conditions (pressure gradient)
What are Black Smokers?
Cold water from ocean penetrates down, gets heated in convective layer, hot fluids then rise before hitting the cold water in the ocean, and the metals drop out. Over time this forms chimneys of minerals
What are Porphyry Deposits?
Deposits forming from continual cycles of presure forming and thereby many generations of mineralization forming upwards towards the surface
What is Supergene enrichment
- Elements leached out of surface zone
- Concentrates at water table
- Can raise ore to minable concentrations
Describe Magmatic Ore Deposits
- Due to segregations (separation) of minerals in mafic or ultramafic intrusion
- Settle because of high density and low magma viscosity
What are Placer Deposits?
- Deposition of high density, resistant minerals in unconsolidated sand and gravel (e.g. gold)
