Architecture of the western Dabieshan HP/UHP terrane, China: constraints from thermobaric pattern and isotopic dating Xiaochun Liu (Institute of Geomechanics, CAGS; Department of Geosciences, National Taiwan University); Bor-ming Jahn (Department of Geosciences, National Taiwan University); Shuwen Dong (Institute of Geomechanics, CAGS); Sanzhong Li (College of Marine Geosciences, Ocean University of China) As the best preserved high- and ultrahigh-pressure (HP and UHP) metamorphic terrane in the Qinling-Dabie-Sulu orogen, western Dabieshan could be divided into six lithotectonic units, i.e., from north to south, the Nanwan flysch, Balifan tectonic mélange, Huwan HP eclogite, Xinxian UHP eclogite, Hong’an HP eclogite and Mulanshan blueschist-greenschist units. In these units five eclogite-bearing zones (I-V) are developed. Based on various thermobarometries, the peak P-T conditions of eclogite are estimated to be 550-570C and 21 kbar for Zone I, 470-500C and 14-17 kbar for Zone II, 620-670C and 26-29 kbar for Zone III, 530-560C and 20-22 kbar for Zone IV, and 490-510C and 19-20 kbar for Zone V. The zircon U-Pb data of eclogites from the Huwan and Hong’an units suggest that their protoliths were formed during the Neoproterozoic, from 733 10 Ma to 684 15 Ma, whereas the metamorphic ages are all the Triassic, about 230 Ma. The symmetrical thermobaric pattern and identical age data demonstrates that the Huwan and Hong’an units belong to the same HP slice overlying the UHP slice. Zircons from a metagabbro in the Balifan unit also yield a Neoproterozoic emplacement age, but slightly younger at 582 11 Ma. Taking into account the Yangtze signature for the Nanwan unit, we infer that the Balifan tectonic mélange and Nanwan flysch units might represent the basement and cover accretionary complexes, respectively, sliced from the Yangtze craton during its northerly subduction. Accordingly, the northern boundary fault of the Nanwan unit should be the Triassic suture between the Sino-Korean and Yangtze cratons. Clear metamorphic gaps between different slices and their diachronous exhumation (from ca. 240 Ma to ca. 210 Ma) could be explained by a successive subduction of underlying slices with a nearly concomitant exhumation of overlying slices.