Partial melting and phase relations in high-grade metapelites: an experimental petrogenetic grid in the KFMASH system

摘要: Petrogenetic grids are a powerful tool for understanding metamorphic terrains and many theoretical have been suggested the process of granulite formation in metapelitic rocks, via fluid-absent biotite melting reactions. However, application these has difficult due to lack suitable experimental constraints. We present here an experimentally determined tightly constrained petrogenetic grid KFMASH system metapelites which extends from 840–1000°C 5.0–12.5 kbar. Sixty four experiments on three KFMASH, mineral-mix, bulk compositions (XMg=0.62, 0.74, 0.86) provide phase composition assemblage data can be derived constrained. Reversal consideration show close equilibrium. The univariant reactions occur between 850 870°C at 5 kbar 900 915°C 10 These connected equilibria beyond stability develop fixed framework within evolution rocks interpreted. effect minor components is evaluated using as simple-system reference. temperature occurs strongly controlled by concentrations titanium fluorine biotite. Pressure-temperature pseudosections presented each both divariant available particular composition, clearly illustrating possible assemblage. also constrain limits