Geology of commodities Flashcards
What is the definition of a resource?
A substance that is naturally obtained from the earth
What are some examples of resources?
Uranium, Gold, Aluminium, Chromium and Zinc
What does every resource have?
An average crustral abundance and concentration factor
What has the highest average crustal abundance?
Aluminium (8%)
What has the lowest average crustal abundance?
Uranium (0.00016%)
What are the three types of copper deposit formed by plate tectonics?
Porphyr copper
Sedimentary copper
Volcagenic massive sulphides
What does the movement of plate tectonics form?
Ore forming environments for mineral deposits
What is copper used in?
Power generation
Building construction
Cars
Electric/hybrid cars
Where does copper form?
Convergent plate margins e.g. pacific ring of fire
What countries have the largest reserves of copper?
Chile
Australia
Peru
Russia
What is the definition of porphyr copper?
Copper ore associated with hydrothermal fluids rising from mamgma chamber
What is the common and important type of deposit?
Porphyr (50% of copper production)
What method of mining is used for porphyry copper deposists?
Open pit mining
How does a porphryr ore form?
Oxidised melts transport volatiles to the upper crustal magma chamber
Fractional crystallisation
Volatile exsolution
What % of copper comes from stratiform sedimentary copper deposits?
25%
How does copper form at volcagenic massive sulfide ore deposits?
Hydrothermal alteration in submarine envrionments
Forming copper sulphide
What is the structure of a porphyry copper deposit?
Low pyrite outer zone with a high pyrite intermediate zone inside, low total sulfide innermost zone with ores either side it
What are the 3 stages of crackle brecciation?
Vapour pressure building up in and around the upper portion of magmatic fraction
Retrograde boiling occurs causing expansion
Distribution of resulting brecciation
Simply, why does copper deposit form?
Moving copper from large volume of magma into a smaller volumed of veined rock
