How High Are the P-T Conditions for Paleoproterozoic Metamorphism of the Huangtuling Felsic Granulite, North Dabieshan, Central China?

Abstract

The 2. 34 cm-wide garnet porphyroblast in the Paleoproterozoic felsic granulite from the Huangtuling area, North Dabieshan, has been reinvestigated for compositional variation in light of Cacomposition X-ray mapping to obtain peak P-T conditions of granulite-facies metamorphism. A new core-rim traverse was conducted through where there is little influence on Ca-profile and slight modification in Mn-, Mg- and Fe-profiles with the highest Mg/(Mg+Fe) value of 0. 467. Reasonable peak P-T conditions were estimated to be 1.50-1.70 GPa and 1 100-1 150 °C according to TWQ-based garnet-Al-orthopyroxene thermobarometry. These estimations suggest that the Huangtuling granulite once was subjected to ultrahigh-temperature (UHT) granulite-facies metamorphism following a high-pressure granulite-faices metamorphic stage, implying that a deep subdaction and collision process relevant to the Yangtze block occurred in the Paleoproterozoic time, probably as a response to the global assembly event of the Columbia supercontinent. © 2006 China University of Geosciences.