Chemical characteristics of migmatites: accessory phase distribution and evidence for fast melt segregation rates

Article Abstract:

In Kirtomy Migmatite Suit in Sutherland, Scotland, the deformation-enhanced melt extraction occurs rapidly. The leucosomes have low Zr content and positive Eu anomalies. They are unable to get equilibrated in the accessory phases. The geochemical and petrographic characteristics of partial melting in pelitic and semi-pelitic lithologies, and their major and trace element analysis supports this conclusion. The accessory phases bearing the rare-earth-elements, remain as residual phase and get concentrated in the melanosome and the melanosome-leucosome boundary.

Scotland, Rock deformation, Geochemistry

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The effect of feldspar on quartz-H2O-CO2 dihedral angles at 4 kbar, with consequences for the behaviour of aqueous fluids in migmatites

Article Abstract:

A study of the impacts of feldspar on dihedral angles in the quartz-H2O-CO2 system at four kbar and between 450 and 1,050 degrees centigrade reveals dihedral angles in feldspar-bearing quartz quantities as similar to those in pure quartz quantities below 500 degrees centigrade, above which temperature and dihedral angles are inversely proportional. The temperature-induced change of quartz-albite-H2O from nonconnected to connected permeability is a probable regulator of porosity of high-grade rocks to aqueous liquids.

Influence, Crystals, Crystal structure, Temperature

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Time of formation and peak of Variscan HP-HT metamorphism of quartz-feldspar rocks in the central Erzgebrige, Saxony, Germany

Article Abstract:

A study was conducted to determine the time of formation and the metamorphism of quartz-feldspar rocks of the Gnesis-Eclogite Unit (GEU) of the Variscan Erzgebirge, Germany. Results showed that after high pressure/high temperature equilibration, the GEU experienced strong near-isothermal decompression at high temperatures, extensive re-equilibration at medium pressures and fast cooling during continued uplift. Moreover, the tectono-evolution and protolith formation occurred between 470 and 524 Ma.

Germany, Metamorphism (Geology), Formations (Geology), Geological formations

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