U2 T11 Flashcards
Igneous
Rocks or processes involving molten rock
Batholith
A large underground mass of solidified molten magma
Hydrothermal
Processes or deposits associated with hot water
What kind of processes provided local concentrations of minerals
Geological processes
Local concentration of minerals can still be present but in very small amounts, so difficult to find. How can an understanding of those processes help us?
It can help us as it will show which other geological formations would be expected in the surrounding areas.
magma can be forced up towards the surface. It may reach the surface. (Faire une jolie phrase en expliquant ce qu’il se passe)
It may reach the surface as an igneous extrusion where it will cool rapidly and form the fine-grained rock such as basalt
Some magma may fail to reach the surface (Faire une jolie phrase en expliquant ce qu’il se passe)
Some magma mail fail to reach the surface, forming a large molten mass of intrusive rock. This is insulated by the surrounding rock so it cools slowly, producing larger crystals and giving more time for minerals to be separated into localised concentrations that can be exploited.
Where are found most metals? (Tin, copper, lead)
In hydrothermal deposits
What happens to the rocks around the batholith
The rocks around the batholith may be lifted and deformed so cracks or fissures form. These may allow hot solutions containing dissolved minerals to escape towards the surface. As the solution cool down, the minerals are deposited in a predictable order according to their solubility.
Explain briefly the sedimentary processes
Sedimentary processes occur at the surface of the lithosphere. A rock that already exists is broken down by weathering into rock particles (regolith) and dissolved minerals in solutions (solutes). These are carried away, separated and may be redeposited elsewhere as rocks with quiet different compositions and properties.
Explain briefly Alluvial/ placer deposits and the difference between.
Alluvial/ placer deposits have been carried by flowing water but are deposited when the water slows down. Different minerals are deposited in différente part of the river, with densest ones settling out firs. Alluvial deposits include materials such as soil or weathering rocks and placer deposits include dense minerals such as gold and tin
When are formed evaporites?
Evaporites are formed when water evaporated from mineral rich solutions. Minerals crystalline as the solutions become saturated, each mineral reaching saturation at a different time so they become saturated, each mineral reaching saturation at a different time so they become separated in different layers.
From what are produced biological deposits?
They are produced from dead animals and plants.
How fossil fuels were produced?
They were produced by dead organisms partially decaying in anaerobic conditions (biological deposits)
Chalk and many limestone are formed from…
Shells of marine organisms
