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The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ...
Partial melting is the phenomenon that occurs when a rock is subjected to temperatures high enough to cause certain minerals to melt, but not all of them. Partial melting is an important part of the formation of all igneous rocks and some metamorphic rocks (e.g., migmatites), as evidenced by a multitude of geochemical, geophysical and petrological studies.
Alkaline magmas are characteristic of continental rifting, areas overlying deeply subducted plates, or at intraplate hotspots. [2]: Ch6 They are more likely to be generated at greater depths in the mantle than subalkaline magmas. [2]: Ch23.6. Alkaline rocks are rare in the Archean, but become common in the Proterozoic.
Adakite. Adakites are volcanic rocks of intermediate to felsic composition that have geochemical characteristics of magma originally thought to have formed by partial melting of altered basalt that is subducted below volcanic arcs. [2] Most magmas derived in subduction zones come from the mantle above the subducting plate when hydrous fluids ...
Anatexis. Anatexis (via Latin from Greek roots meaning "to melt down") is the partial melting of rocks. [1] Traditionally, anatexis is used specifically to discuss the partial melting of crustal rocks, while the generic term "partial melting" refers to the partial melting of all rocks, in both the crust and mantle. [citation needed]
This effect of partial melting is reflected in the compositions of different magmas. A low degree of partial melting of the upper mantle (2% to 4%) can produce highly alkaline magmas such as melilitites, while a greater degree of partial melting (8% to 11%) can produce alkali olivine basalt. [80]
The pressure and temperature increases induce the partial melting of the delaminated mafic block to generate TTG magma, which rises and intrudes to the crust. In the lower figure, mantle plume rises to the base of the mafic crust and thicken the crust. The partial melting of the mafic crust due to the plume heating generates TTG magma intrusions.
Earth's crustal evolution involves the formation, destruction and renewal of the rocky outer shell at that planet 's surface. The variation in composition within the Earth's crust is much greater than that of other terrestrial planets. Mars, Venus, Mercury and other planetary bodies have relatively quasi-uniform crusts unlike that of the Earth ...