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When rock melts, the liquid is a primary magma. Primary magmas have not undergone any differentiation and represent the starting composition of a magma. [96] In practice, it is difficult to unambiguously identify primary magmas, [97] though it has been suggested that boninite is a variety of andesite crystallized from a primary magma. [98]
The formation of pull-apart basins along strike-slip faults causes decompression melting. Advection of melts and heat flux into the lower crust results in partial melting of crustal rock. [ 16 ] The buoyant magma rises due to its lower density and is able to exploit weaknesses such as fault planes, using strike-slips as conduits for motion.
Magmatism. Geological map showing the Gangdese batholith, which is a product of magmatic activity about 100 million years ago. Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production ...
Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. 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.
The magmatic aspects of plate tectonics tends to gradual segregation within or between the mantle and crust. As magma forms, the initial melt is composed of the more silicic phases that have a lower melting point. This leads to partial melting and further segregation of the lithosphere. In addition the silicic continental crust is relatively ...
In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of (usually increasingly silicic) magmas produced by igneous differentiation is known as a magma series.
In essence, fractional crystallization is the removal of early formed crystals from an originally homogeneous magma (for example, by gravity settling) so that these crystals are prevented from further reaction with the residual melt. [3] The composition of the remaining melt becomes relatively depleted in some components and enriched in others ...
The Pressure-Temperature-time path (P-T-t path) is a record of the pressure and temperature (P-T) conditions that a rock experienced in a metamorphic cycle from burial and heating to uplift and exhumation to the surface. [1] Metamorphism is a dynamic process which involves the changes in minerals and textures of the pre-existing rocks ...