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Magma can be found in the mantle or molten crust. Magma (from Ancient Greek μάγμα (mágma) 'thick unguent') [1] is the molten or semi-molten natural material from which all igneous rocks are formed. [2]
Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet 's mantle or crust . Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure , or a change in composition.
A magma chamber is a large pool of liquid rock beneath the ... Upon cooling, new mineral phases ... the rate of magma production in tectonic settings that produce ...
Under this theory, the fuel (in this case, the magma) fragments upon contact with a coolant (the sea, a lake or aquifer). The propagating stress waves and thermal contraction widen cracks and increase the interaction surface area, leading to explosively rapid cooling rates. [ 1 ]
Magma rapidly cooled to below its normal crystallization temperature becomes a supercooled liquid, and, with further rapid cooling, this becomes an amorphous solid. The change from supercooled liquid to glass occurs at a temperature called the glass transition temperature, which depends on both cooling rate and the amount of water dissolved in ...
Porphyritic textures develop when conditions during the cooling of magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a fine-grained (aphanitic) matrix.
Because the solid country rock into which magma intrudes is an excellent insulator, cooling of the magma is extremely slow, and intrusive igneous rock is coarse-grained . However, the rate of cooling is greatest for intrusions at relatively shallow depth, and the rock in such intrusions is often much less coarse-grained than intrusive rock ...
Magma emplacement can take place at any depth above the source rock. [4] Magma emplacement is primarily controlled by the internal forces of magma including buoyancy and magma pressure. [2] Magma pressure changes with depth as vertical stress is a function of the depth. [20] Another parameter of magma emplacement is the rate of magma supply. [2]