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Rare-element Pegmatite (Allanite)

Chemical Process (Liquid-phase Growth) - Closed system under ground (Melt precipitation)




Allanite-Monazite type < REE subclass < (NYF family) < Rare-element class < Granitic pegmatite

Required Geological Setting

Plutonic rocks


Pegmatites formed by fractional crystallization of I-type granite magma. Pegmatites are emplaced at shallow depth, and distribute at interior to marginal zones of granite batholiths. Most of pegmatites are reported from passive continental margin granites in extentional crustal settings such as the Atlantic Ocean. Textures of host rocks are clearly cut by pegmatites, and host rocks are subjected to contact metamorphism by granites or pegmatites. Pegmatites are massive and pockets are very rare. The Allanite-Monazite type is characterized by abundant light rare-earth elements such as La, Ce, and Nd.

Rare-element Pegmatite (Allanite)

Distribution of the allanite-monazite type rare-element pegmatites described in this site. Red is ilmenite-series granites corresponding to S-type granites, and blue is magnetite-series granites corresponding to I-type granites.

Mineral Assemblages (Major minerals)

Quartz, Microcline, Albite, Muscovite

Mineral Assemblages

Allanite-(Ce), Monazite-(Ce), Zircon, Rutile, Fluorite, Ilmenite

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