OCR A-Level Geology natural resources and economic geology overview quiz quiz

Mechanical concentration of dense copper grains by fast-flowing river water (placer sorting)

Surface weathering that leaches copper away and leaves only insoluble residue behind

Gravity settling of dense early-formed crystals on a magma chamber floor

Hot mineral-rich fluids disseminating copper through a large body of rock (hydrothermal)

Dense, resistant minerals such as gold or cassiterite

Light, soluble minerals that readily dissolve and are carried away in solution

Volcanic gases trapped and concentrated within the river sediment

Soft clay minerals produced by chemical weathering of feldspar

Precipitation of aluminium minerals from hot hydrothermal veins cutting the bedrock

Residual concentration by intense chemical weathering in warm, wet climates

Magmatic segregation of aluminium-rich crystals settling within a cooling intrusion

Placer concentration of dense aluminium grains in fast-flowing rivers

Ore is the worthless waste material, while the gangue is the valuable extractable part

They are the same thing, both simply meaning any mineral found inside a rock body

Ore is a deposit extractable at a profit; gangue is the worthless associated minerals

Ore is always gold and gangue is always quartz, regardless of the deposit type

The highest grade ever recorded anywhere within the deposit during sampling

The total tonnage of ore plus waste that the whole deposit is estimated to contain

The maximum depth below the surface at which the deposit can still be reached

The lowest grade that can be mined at a profit under current costs and prices

40,000 t

4000 t

400,000 t

8000 t

Reserves fall, because the higher price forces every active mine to shut down completely

Reserves rise, because lower-grade material crosses the cut-off and moves from resource into reserve

Reserves are completely unaffected, since the metal price has absolutely no bearing on the cut-off grade at all

Resources shrink below the size of reserves once the metal price climbs higher

Reservoir first, then source, then seal, then migration, and finally the trap forms

Trap, then seal, then reservoir, then source, with maturation occurring last of all

Source rock, maturation, migration, reservoir, trap and seal

Migration, then trap, then source rock, then seal, with the reservoir forming last

Porosity on its own is enough, because pore space alone lets the hydrocarbons flow freely to the well

Permeability is what physically stores the hydrocarbons, while porosity simply lets them move through the rock

A reservoir does not actually need to have any permeability at all, provided only that its total measured porosity is high enough

Permeability (connected pores) is needed for hydrocarbons to migrate in and flow to a well; porosity only stores them

Peat, lignite, bituminous, anthracite

Anthracite first, then bituminous, then lignite, with peat as the highest rank

Lignite, then peat, then anthracite, then bituminous as the final highest rank

Bituminous, then anthracite, then peat, then lignite as the highest-carbon coal

Porosity measures how fast fluid flows through, while permeability measures the total pore space available

Porosity is the proportion of pore space (storage); permeability is how connected the pores are (flow)

They are identical terms, both simply describing the total amount of empty space inside a rock

Porosity is a property that applies only to sandstone and to no other type of sedimentary rock

6 percent

30 percent

15 percent

85 percent

The cross-sectional area through which the groundwater is flowing in the aquifer

The hydraulic conductivity, a measure of the permeability of the aquifer material

The porosity, meaning the total proportion of pore space within the aquifer rock

The hydraulic gradient (slope of the water table or pressure surface)

Saltwater intrusion, as seawater moves inland into the aquifer

The water table rises steadily as the freshwater head builds back up again

The aquifer rock gradually becomes far more porous than it was beforehand

The permeability of the aquifer increases as the pores are flushed clear