Petrology and fluid inclusions of a quartz-kyanite segregation in the main thrust zone of the Himalayas

Abstract

Fluid inclusion data are compared to P-T estimates from coexisting minerals in a quartz-kyanite segregation and in the surrounding garnet-bearing micaschist. Mineral assemblages, notably plagioclase-garnet-kyanite-quartz, record a retromorphic evolution from 550–600°C, 7–8 kb to 450–500°C, 3–4 kb. The density of the early fluid in the segregation (H 2O + 9 to 15 mole % CO 2) is compatible with this last set of values; it suggests a continuity of the evolution in the metamorphic rock and in the segregation and an early separation of the during postmetamorphic uplift.