Discovery and implications of granulite facies metamorphic rocks in the eastern Nanling, China.

This paper presents the petrologic characteristics of the granulite facies metamorphic rocks found for the first time in the eastern Nanling, South China. Their protoliths are sedimentary rocks based on the mineral assemblages and compositions. Petrogenetic grid and T-P calculations indicate that the peak metamorphism took place at temperature of 750 -880℃ and pressure of ~ 1.1GPa. It is suggested that these surficial sediments were carried into lower crust by some tectonic processes, and underwent granulite facies metamorphism. P-T-t path of isothermal decompression indicates rapid exhumation history, which was likely related with Mesozoic extension. The compositions of the Nanling granulites are evidently different from those of mafic granulite xenoliths in the coastal region of southeastern China, implying that the lower crust components beneath both regions are possibly different. Accordingly, the distinct type of granites in both regions resulted probably from the difference of lower crustal composition.