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Abstract: Based on field mapping, section measurement and magnetostratigraphy, ∼1700m of sedimentary rocks have accumulated in the Wushan basin between ∼16Ma and ∼6Ma. Basin geometry, sedimentation characteristics and the early syn-depositional deformation along the northern margin of the basin indicate that formation of the Wushan basin was related to tectonic deformation along the West Qinling fault zone during the middle Miocene. A series of basins of similar age to the Wushan basin were generated along and to the south of the West Qinling fault zone while basalts also erupted in this region at this time. We suggest that the middle Miocene (∼16Ma) may represent a change in kinematics and deformation style in the region along and to the south of the West Qinling fault zone. At this time, there was a transition from NNE–SSW compressional deformation, that dominated the region since the late Paleogene, to the development of WNW–ESE and/or E–W trending strike-slip movement and associated transpressional and transtensional activity that continues today. The Miocene Wushan basin may have developed in association with transpression along the West Qinling fault zone. Whether this transition was related to the onset of strike-slip along the east Kunlun fault and related deformation transfer, lower crustal flow, or removal of mantle lithosphere, the middle Miocene provides direct evidence for a change in the kinematic style along the plateau margin. [Copyright &y& Elsevier]

Abstract: The Liupan Shan Mountain is one of the outermost ranges in northeastern Tibetan Plateau. The onset of its uplift provides insight on whether the plateau grew sequentially outward or broad areas of the plateau deformed simultaneously. The apatite fission-track method can be used to date rapid cooling as the result of unroofing of rocks in response to tectonically induced vertical motion. Fission-track data from apatite in Early Cretaceous sedimentary strata exposed on the hanging-wall of Liupan Shan thrust fault in northeastern Tibet suggest that a late Cenozoic rapid cooling events occurred at 7.3–8.2 Ma or ~8 Ma. This age apparently dates fault activity of the Liupan Shan thrust in response to northeastward growth of the Tibetan Plateau uplift and lateral growth, which continues today. Numerous studies of the Tibetan Plateau suggest that the onset of deformation in eastern and northern margin of Tibetan Plateau occurred in the latest Miocene. [Copyright &y& Elsevier]