The Tianshan range could have been built by both late Early Paleozoic accretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture is marked by Ordovician ophiolitic mélange and a Silurian flysch sequence, high-pressure metamorphic relics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanic arc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along with unconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation. The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductile shearing, yielding granulite-bearing ophiolitic mélange blocks and garnet-pyroxene-facies ductile deformation, and the later deformation, a dextral strike-slip tectonic process, occurred during the Late Carboniferous(Early Permian. Early Carboniferous molasses were deposited unconformably on pre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny. The large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by the second tectonic event, the Hercynian collision between the northern Tarim block and the southern Siberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this Early Paleozoic deformation belt. Results of geometric and kinematic studies suggest that the primary framework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, was built by these two phases of accretion events.
The paper of Shen et al., entitled "Surveying of the deformed terraces and crust shortening rate in the northwest Tarim Basin", was published in Chinese Science Bulletin (Vol. 46, No. 12). Shen et al. found the deformation of Late Pleistocene to Holocene terraces of the Boguzi River across the Artushi Anticline in the northwest Tarim Basin close to the Pamir, and made level survey and differential GPS measurement, which is of great importance to geodynamics for research on the coupling of Tianshan Mountains uplifting and Tarim Basin depression. But their understanding to the deformation mechanics of terraces and the calculation methods of crustal shortening are open to discussion. Therefore, we discuss it with Shen Jun et al.
