~990 Ma peak granulitic metamorphism and amalgamation of Oaxaquia, Mexico: U-Pb zircon geochronological and common Pb isotopic data

The ~1 Ga Oaxacan Complex is the largest exposure of the Oaxaquia terrane of Mexico. Microprobe analysis of co-existing ortho- and clino-pyroxene, garnet, ilmenite and plagioclase indicate metamorphic conditions of 735 ± 5° C and 7.7 ± 0.1 kbar in the granulite facies, which was dated between ~998 and ~979 Ma using U–Pb isotopic analyses of zircon populations. Peak temperatures >800° C and isobaric cooling are indicated by the sporadic presence...