Lithosphere
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What is an In Situ resource?
a resource that is extracted from where it is made
What happens to an In Situ resource as it is extracted
it is depleted UNLESS they are made rapidly
How long do most geological, resource making processes take?
thousands/millions of years
Give examples of In Situ resources that are: a) formed slowly b) formed faster
a) fossil fuels metal ores rocks b) sand gravel
What are the three main rock types and how can we generally identify them?
Sedimentary - has layers/fossils/clasts Igneous - crystalline Metamorphic - changed by heat and/or pressure, also has layering/folding
Give two example metals extracted from the crust, their global annual production in tonnes, and examples of their major uses
• Iron 1700 million tonnes Buildings: girders Transport: ships Appliance casing: fridges • Copper 19 million tonnes Electric cables, water pipes
Give two examples of minerals/materials extracted from the crust, their global annual production in tonnes, and examples of their major uses
• Limestone 600 million tonnes Cement Building blocks • Aggregates (sand/gravel) 40 billion tonnes Concrete Building mortar Glass
What are igneous processes?
the processes by which rocks and minerals are created by the cooling and hardening of magma or molten
What can igneous processes create?
mineral veins
Give an example of an igneous process
Hydrothermal deposition
How does hydrothermal deposition work?
• Igneous intrusion produces pressurised superheated water at high temps • That water dissolved many minerals from the surrounding rock • The mineral-rich solutions travel along fissures away from the igneous batholith, and cool • As they cool, dissolved minerals come out of solution (crystallise) in order of solubility
Why is hydrothermal deposition useful?
Before solution and crystallisation, it is just a mixture of minerals that cannot be exploited - soon after the batholith forms, minerals separate and deposit, and exploitation becomes possible
Give some examples of metal ores deposited by hydrothermal processes
tin copper lead silver gold arseinc
What is an ore?
naturally occurring solid material from which a metal or valuable mineral can be profitably extracted a rock that contains a significant quantity of ore minerals/rock with a relatively high concentration of a particular metal
Give an example of a valuable mineral in a vein
Gold Silver Lead ore
What are metamorphic processes? give examples
when igneous processes and tectonic movements of crustal plates alter existing igneous/sedimentary rocks with high temp and/or pressure e.g. limestone to marble, mudstone to shale
What are sedimentary processes?
Where minerals settle and build up to produce layers of sediment The deposition and cementation at the Earth’s surface and in water bodies creates sedimentary rocks/minerals
What are the four sedimentary deposits?
• Proterozoic Marine Sediments (banded iron deposits) • Alluvial deposits • Biological sediments • Evaporites
What are Proterozoic Marine Sediments?
• Where iron ore deposits form when dissolved iron compounds became oxidised by oxygen released • due to the abundance of photosynthesising organisms • between 2.5 and 1.8 million years ago
What are Alluvial deposits? Give some examples
• ancient ore veins eroded by flowing water (e.g. rivers) and deposited in river sand and gravel • the ability of the water to carry solids depends on velocity of water and density of solids • gold, diamonds, tin ore
What are Evaporites? Give an example
• when ancient seas become isolated, water evaporates leaving crystallised minerals • also forms in inland seas in desert areas due to river evaporation • halite (sodium chloride)
What are biological sediments?
• where living organisms form the mineral deposits e.g. shells, guano, plankton, dead plants • the processes concentrate minerals that are then deposited in sedimentary rocks
What biological material forms: a) limestone and chalk b) coal c) crude oil and natural gas
a) shells of marine organisms b) terrestrial vegetation c) marine organisms
What is secondary enrichment?
• if the initial mineral was soluble, it may dissolve from one rock, and move through the groundwater to a new place • the groundwater leaches and oxidises primary ores, adding O2, OH, CO2 • as oxidation state changes, it gets deposited • creates ores 10x richer than the original