High-T/UHP Metamorphism and Multistage Exhumation History of the North Dabie Complex Zone
详细信息   
摘要

Recent investigations of metamorphic rocks from North Dabie complex zone (NDZ) suggest that the NDZ wholly underwent high-T/UHP metamorphism and multistage exhumation history. The eclogites are characterized by high-T metamorphism and multiple symplectites that formed by granulite-and amphibolite-facies metamorphism during decompression. The occurrence of radial cracks around quartz inclusions and of polycrystalline quartz inclusions in garnet, most likely suggests that these inclusions formerly were coesite, now inverted to quartz. These data demonstrate that the NDZ wholly experienced the Triassic deep subduction and UHP metamorphism.  The multiple coronitic and symplectitic reaction textures and the occurrence of compositionally zoned minerals such as garnet and clinopyroxene record multistage rapid exhumation of the UHP eclogites. Their metamorphic P-T conditions and isotopic ages for various stages show that they experienced a protracted high-T period with slow cooling process.