Metamorphic evolution and SIMS zircon U-Pb geochronology of mafic granulite and amphibolite enclaves of the Pingyang trondhjemitic pluton, Fuping terrane, North China

摘要

Highlights?The Pingyang trondhjemitic pluton formed at ～2.52Ga.?The mafic granulite and amphibolite enclaves record clockwiseP-T-tpaths.?The mafic granulite enclaves metamorphosed at ～1.89–1.86Ga.AbstractThe discrete mafic granulite and amphibolite enclaves within the Pingyang trondhjemitic pluton, Fuping metamorphic terrane, middle Trans-North China Orogen, ubiquitously record three stages of metamorphic assemblages. For the mafic granulite enclaves, the prograde metamorphic assemblage (M1) is represented by mineral inclusions (clinopyroxene+hornblende+plagioclase+quartz±apatite) preserved in the garnet porphyroblast, the metamorphic peak (M2) assemblage consists of garnet and matrix minerals of clinopyroxene+orthopyroxene+hornblende+plagioclase+quartz±magnetite±ilmenite±zircon, and the retrograde (M3) stage is represented by symplectite assemblage of orthopyroxene+plagioclase±clinopyroxene±hornblende±quartz rimming the garnet porphyro