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The formation of igneous rock from magma.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the processes of the formation of magma, its subsequent development, displacement, interaction with solid rocks, and solidification.

As one of the most important manifestations of deep-seated activity of the earth, magmatism is directly or indirectly bound up with the development of the earth, its thermal history, and its tectonic evolution. When the nature of tectonics changes there is also a change in the type of magmatism; depending on geological history and confinement to some particular structure of the earth’s crust magmatism is subdivided into geosynclinal, platform, oceanic magmatism, and magmatism of activization areas. Depending on the depth of manifestation (conditions of magma solidification) magmatism is divided into abyssal, hypabyssal, subvolcanic, and surface magmatism. (The last is known as volcanism.) By composition the breakdown is ultrabasic, basic, acid, and alkali. Some experts believe that magmatic processes are especially intensive in the geosynclinal period of the development of folded areas and that certain forms of the manifestation of magmatism are associated with definite stages in the development of a geosyncline. In the modern geological epoch magmatism is especially highly developed in the Pacific geosynclinal belt, the midocean ridges, the rift zones of Africa and the Mediterranean region, and elsewhere. The formation of many different deposits of minerals is associated with magmatism.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
All these suggestions are compliant with previous conclusions from the X-ray luminescence of feldspar on common source of the Novosibirsk-Ob Area granitoids formation (Boroznovskaya et al., 2012), which allows us to consider the KTFB granitoid magmatism as the result of natural magmatic differentiation of the parental magma, providing a viable possibility to implement the quartz emission spectra in solving the problems of typification of granitoid massifs and other geological formations.
However, the lateral intraplate magmatism of the crust can also generate characteristics similar to those of island arc granite (Plank, 2005).
In contrast, the Redstone Mountain Granite is chemically more typical of within-plate magmatism, and forms a bimodal association with spatially-related mafic intrusive rocks.
The decompression beneath the lithosphere is likely to lead to basaltic magmatism along and below the swell of the antiform.
(1981) Gradients in silicic magma chambers: implications for lithospheric magmatism. J.
This age is similar to the age of radiolarians from the lower strata of the Maizuru Group and may represent the magmatic age of the mafic rocks of BABB origin without the influence of arc magmatism.
The Zn-enrichment of coal seams of the western zone of the USCB may result from the raised geothermal gradient, typical for this region, and magmatism accompanied by various forms of mineralization (Table 3).