Recently we have firstly recognized an ultrahigh-temperature (UHT) metapelitic granulite from the migmatitic parneiss near Kalasu in the Chinese Altai, NW China, with an assemblage of Gt-Opx-Sil-Cd-Sp-Bt-P1-Qtz. Orthopyroxene shows a high-A1 feature, with an AL2O3 content in excess of 8. 0% , indicating that its peak metamorphism reached UHT conditions ( 〉 900℃ ). P-T estimate results show its peak metamorphic conditions as: P =~ 8kb, T = ~ 960℃. The preliminary P-T estimate results indicate an anticlockwise P-T path with a post-peak near isobaric cooling. Through LA-ICP-MS technique, the U-Pb age dating for zircons from the UHT metapelitic granulite has been undertaken, and the age data are mainly between 260 ~ 280Ma, with an intercept at 271 ± 5Ma, sparse ages of 380 ~390Ma, and detrital ages mainly between 450 ~ 500Ma. The age data support that the UHT metamorphic event in the Ahai orogen occurred during the Permian, highly consistent with the timing of the Permian Tarim mantle plume ( ~275Ma), and also coeval with the extensive Permian (260 ~280Ma) post-orogenic or anorogenic mafic and granitic intrusions in the region. Thus, the Permian UHT metapelitic granulite in the Ahai orogen may be closely associated with a magmatic underplating and extensional heating in the lower crust, as a result of the Permian Tarim mantle plume event, and this is also compatible with its anticlockwise P-T path.
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