Timing of metamorphism and formation of garnet granite in the Kontum Massif, central Vietnam: Evidence from monazite EMP dating

Abstract

Garnet bearing granite (Grt granite) and high grade pelitic gneisses occur in the Kannak Complex, southern Kontum Massif, central Vietnam. Electron microprobe (EMP) dating of monazite in Grt granite and garnet orthopyroxene gneiss (Grt Opx gneiss) gave ages of ca. 260 Ma from cores and ca. 230 Ma from thin rims. Since most monazite grains are predominately of core composition, the ca. 260 Ma age indicates the timing of high temperature metamorphism and the formation of Grt granite. Grt granite is locally accompanied by coeval intrusions of fine grained gabbro, which is a candidate for the heat source leading to high grade metamorphism and partial melting of the crust during the Late Permian.

Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis

“…This age is consistent with the UHT metamorphism reported from the Kontum massif in the Indochina block (Nakano et al, , 2009Nam et al, 2001;Osanai et al, 2001Osanai et al, , 2004Owada et al, 2006Owada et al, , 2007. For instance, electron microprobe (EMP) dating of monazite showed that the timing of the metamorphism was ca.…”

“…This event exerted a strong effect on both of the SCB and the Indochina block (Chen et al, 2011;Trung et al, 2006). In the Indochina block, the Kontum massif in central Vietnam experienced ultrahightemperature metamorphism in the late Permian (Nakano et al, , 2009Nam et al, 2001;Osanai et al, 2001Osanai et al, , 2004Owada et al, 2006Owada et al, , 2007. As a counterpart of the Kontum massif in the SCB (Chen et al, 2011), contemporaneous HT granulite-facies metamorphism occurred in the DSGB.…”

“…For instance, electron microprobe (EMP) dating of monazite showed that the timing of the metamorphism was ca. 260 Ma (Owada et al, 2006, and SHRIMP UPb zircon dating yielded a time of ca. 254 (Nam et al, 2001).…”

Low–temperature eclogite–facies bauxite from the Red River shear zone in Vietnam: Its evolution and significance

“…Several different approaches using metamorphic and igneous rocks from northern to central Vietnam and southern China have revealed the Indochina block collided to the South China block at the Permo-Triassic (e.g., Lepvrier et al, 2004, Osanai et al, 2004, Owada et al, 2006Lepvrier et al, 2008;Nakano et al, 2008Nakano et al, 2010aNakano et al, , 2010bFaure et al, 2014;Lai et al, 2014). The thermal regime of low-T eclogite-facies metamorphism documented in this study is attributed to the collisional event because the presence of eclogite-facies meta-bauxite cannot be explained by any other thermal regimes (e.g., subduction zone metamorphism).…”