← Geology syllabus

EnglandGeology

Module 5: Petrology - Fluids and geological processes

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How is water stored in and flows through rocks, and how do we quantify that flow?

Groundwater: porosity and permeability and how they differ between rock types; aquifers, aquitards and the water table; confined and unconfined aquifers; the calculation of porosity from pore and total volumes; the use of a simple form of Darcy's law to relate groundwater discharge to hydraulic conductivity, hydraulic gradient and area; the issues of over-abstraction and contamination.
A focused answer to the OCR H414 dot point on groundwater. Covers porosity and permeability and how they vary between rock types, aquifers, aquitards and the water table, confined and unconfined aquifers, calculating porosity, using a simple form of Darcy's law for groundwater flow, and the issues of over-abstraction and contamination.
13 min answer →

How do oil and gas form, move and become trapped, and what makes a working petroleum system?

Hydrocarbons: the petroleum system (source rock, maturation, migration, reservoir rock, trap and seal); the formation of oil and gas from organic-rich source rocks by burial and heating; the properties needed in a reservoir (porosity and permeability) and a seal (low permeability); the types of trap (structural and stratigraphic); the formation of coal from plant material with increasing rank.
A focused answer to the OCR H414 dot point on hydrocarbons. Covers the petroleum system (source rock, maturation, migration, reservoir, trap and seal), the formation of oil and gas by burial and heating, the porosity and permeability needed in a reservoir, low-permeability seals, structural and stratigraphic traps, and the formation of coal with increasing rank.
13 min answer →

How do economically valuable mineral deposits form and become concentrated?

Ore formation: the processes that concentrate metals into economic mineral deposits (hydrothermal vein and disseminated deposits, magmatic segregation, placer deposits and residual deposits); the conditions and host rocks typical of each; the distinction between ore and gangue and the idea that a deposit is economic only if the metal is concentrated well above its crustal average.
A focused answer to the OCR H414 dot point on ore formation. Covers hydrothermal vein and disseminated deposits, magmatic segregation, placer deposits and residual deposits, the conditions and host rocks of each, the distinction between ore and gangue, and the requirement that a metal be concentrated well above its crustal average to be economic.
13 min answer →

What makes a mineral deposit worth mining, and how is the metal content estimated?

Mining geology: the economic terms (ore grade, cut-off grade, reserves and resources) and the factors affecting whether a deposit is mined (grade, tonnage, depth, location, technology, price and environmental constraints); the calculation of contained metal from grade and tonnage; the extraction methods (open-pit and underground) and the geological and environmental issues of mining (waste, tailings and acid mine drainage).
A focused answer to the OCR H414 dot point on mining geology. Covers ore grade, cut-off grade, reserves versus resources, the factors affecting whether a deposit is mined, calculating contained metal from grade and tonnage, open-pit and underground extraction, and the environmental issues of mining (waste, tailings and acid mine drainage).
13 min answer →