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Abstract. The largest tract of ultrahigh-pressure rocks, the Dabie-Hong'an area of China, was exhumed from 125 km depth by a combination of normal-sense shear from beneath the hanging wall Sino-Korean craton, southeastward thrusting onto the footwall Yangtze craton, and orogenparallel eastward extrusion. Prior to exhumation the UHP slab extended into the mantle a downdip distance of 125-200 km at its eastern end, whereas it was subducted perhaps only 20-30 km at its far western end ~200 km away. Structural reconstructions imply that the slab was > 10 km thick. In the Hong'an area (Figures 1 and 2), blueschist-facies rocks are more widespread, and a distinct eclogite-retrogressed-toamphibolite unit has been mapped, in addition to quartz eclogite and coesite eclogite. Also, a wider variety of Paleozoic metamorphic rocks crop out in E-W trending fault-bounded units

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The New Guinea region evolved within the obliquely and rapidly converging Australian and Pacific plate boundary zone. It is arguably one of the most tectonically complex regions of the world, and its geodynamic evolution involved microplate formation and rotation, lithospheric rupture to form ocean basins, arc-continent collision, subduction polarity reversal, collisional orogenesis, ophiolite obduction, and exhumation of (ultra)high-pressure metamorphic rocks. We describe the major onshore and offshore tectonic and geologic components, including plate boundaries, seismicity, faults, and magmatism, and we integrate these with emerging ideas about mantle dynamics to evaluate the Cenozoic tectonic evolution of New Guinea. Future research opportunities to resolve the mantle structure beneath New Guinea will enable mantle dynamics to be linked to lithospheric and surface processes. Virtually all plate tectonic and mantle processes have been active in the New Guinea region throughout the Cenozoic, and, as such, its tectonic evolution has global significance.