4/2/2024 0 Comments Ultramafic ternary diagramThermodynamic modeling of the ultramafic composition in the MnNCKFMASHTO system shows that anatexis occurred at the end of the prograde P- T path, between the solidus (at ca. Type 1 inclusions are trachytic and ultrapotassic, whereas type 2 melts are dacitic to rhyolitic. The conditions ranged between 900 and 950 ☌ at 1.5–2.4 GPa. The nanogranitoids were re-homogenized after heating in a piston-cylinder in a series of four experiments to investigate their composition. Type 2 inclusions appear to be the crystallization products of a melt that coexisted with an immiscible CO 2-rich fluid. Type 2 inclusions are <30 μm in size, secondary, and contain amphibole, feldspars, and zoisite. They contain kokchetavite, kumdykolite, and phlogopite, with quartz and zoisite as minor phases, and undevitrified glass was identified in one inclusion. Type 1 inclusions, interpreted as primary, are isolated, <10 μm in size, and generally have negative crystal shapes. Garnet contains two generations of melt inclusions. The granulites contain the peak assemblage pargasite+garnet+clinopyroxene with rare relict orthopyroxene and biotite, and retrograde symplectites at contacts between garnet and amphibole. In the Pan-African belt of the Dronning Maud Land, Antarctica, crystallized melt inclusions (nano-granitoids) occur in garnet from ultramafic granulites.
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