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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 ("neosome"), while the alternate layer has a ...
Migmatite is a gneiss consisting of two or more distinct rock types, one of which has the appearance of an ordinary gneiss (the mesosome), and another of which has the appearance of an intrusive rock such pegmatite, aplite, or granite the (leucosome). The rock may also contain a melanosome of mafic rock complementary to the leucosome. [11]
The quartz percentage among felsic minerals in TTG rocks is usually larger than 20% but less than 60%. [1] In tonalite and trondhjemite, more than 90% of the feldspars are plagioclase, while in granodiorite, this number is between 65% and 90%. [1]
Migmatite featuring felsic minerals, at Morton Gneiss Complex. Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme metasomatism. The idea behind granitization was that fluids would supposedly bring in elements such as potassium, and remove others, such as calcium, to transform a ...
Slate--- Phyllite----- Schist----- Gneiss--- Migmatite Chlorite zone Biotite zone Garnet zone Staurolite zone Kyanite zone Sillimanite zone. A more complete indication of this intensity or degree is provided by the concept of metamorphic facies. [78]
Location: the tectonic contact between the (autochthonous) Western Gneiss Region and rocks of the (allochthonous) Blåhø nappe on Otrøy, Caledonides, Central Norway. A mylonite (through a petrographic microscope) showing rotated so-called δ-clasts. The clasts show that the shear was dextral in this particular cut.
In the basin, migmatite gneiss is transgressed by calc-schist, breccia, quartzite, limestone and recrystallized fossils. The Tang Chu Basin, on the other hand, holds Devonian rocks and fossils. Young faults and fracture zones formed in the last 2.5 million years of the Quaternary. These recent tectonic features are found in the central and east ...
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