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Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock that was reconstituted subsequently by partial melting ("paleosome"), while the alternate layer has a ...
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The Migmatite-Gneiss Complex covers half of Nigeria's surface area and encompasses Archean gray gneisses, with tonalite and granodiorite consistencies. Within this complex are occurrences of schist , migmatite , garnet , sillimanite , kyanite and staurolite , which together indicate high-grade metamorphism up to the level of amphibolite on the ...
They are medium to coarse–grained and mainly composed of feldspars sometimes associated with quartz and anhydrous ferromagnesian minerals, with granoblastic texture and gneissose to massive structure. [1] They are of particular interest to geologists because many granulites represent samples of the deep continental crust. Some granulites ...
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.
Enciclopedia Libre Universal en Español (English: Universal Free Encyclopedia in Spanish) was a Spanish-language wiki-based online encyclopedia that started as a fork of the Spanish Wikipedia, released under the Creative Commons Attribution-ShareAlike License 3.0 and using the same MediaWiki software.
[1] L-tectonites have a dominant linear fabric and generally indicate a constrictional type of strain. This may be due to a lack of platey phases. [1] L-S tectonites have equally developed linear and planar fabric elements and may indicate a plane strain deformation. Many mylonites are L-S tectonites consistent with a simple shear deformation.
Blastomylonites are coarse grained, often sugary in appearance without distinct tectonic banding.; Ultramylonites usually have undergone extreme grainsize reduction. In structural geology, ultramylonite is a kind of mylonite defined by modal percentage of matrix grains [clarify] more than 90%. [4]