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Abstract: The northwestern edge of the Tarim Basin, which contains the Kalpin Uplift and the north Bachu Uplift, lies between the South Tianshan and Tarim continental block and its tectonic evolution is closely correlated with the Tianshan. The pre-Mesozoic units are widely exposed in the northwestern edge of the Tarim Basin, which allow detailed geological observation and sample collection. In this paper, the apatite (U–Th)/He thermochronology was used to study the tectono-thermal evolution of the northwestern edge of the Tarim Basin. The sandstone samples from the Upper Neoproterozoic, Silurian, Devonian, Carboniferous and Permian units, etc. on the northwestern edge of the Tarim Basin were collected and used to determine apatite (U–Th)/He ages. The apatite He ages in the Kalpin Uplift reveal the tectonic uplift events during the Late Cretaceous (96–70Ma) and the Miocene (22–20Ma). These uplift events are linked to collisions of the Lhasa Block and the India plate with the southern Eurasian continental margin, respectively. However, apatite He ages in the north Bachu Uplift show only the Eocene event at ∼40Ma because the west Kunlun orogenic belt thrust over the southwestern edge of the Tarim Basin during the Eocene. The thermal modeling results reveal four cooling events in the Kalpin Uplift since the Late Neoproterozoic, corresponding to 460–445Ma, 350–320Ma, 220–210Ma and 20–10Ma but only one episode with 220–210Ma in the north Bachu Uplift since the Devonian. Based on the thermal modeling results, the north Bachu Uplift did not experience the cooling events at 460–445Ma, 350–320Ma and 20–10Ma shown in the Kalpin Uplift. This paper provides a new insight into the tectonic evolution of the Tianshan and the northwestern Tarim Basin. [Copyright &y& Elsevier]

Abstract: The Tongbai orogen in the middle of the Qinling–Tongbai–Dabie–Sulu orogenic belt is one of the most important portions for understanding the tectonic framework and evolution between the Sino-Korean and Yangtze cratons. In this paper, we report new U–Pb and 40Ar/39Ar age data from the Tongbai complex in order to constrain the extensional processes and late exhumation of HP/UHP terranes. Zircon U–Pb dating of different rock types in the Tongbai complex reveals the intrusion of voluminous granitic magmas at 139±2Ma, contact metamorphism and migmatization of the Triassic metamorphic enclaves at 136±2Ma, and syn-deformational emplacement of pegmatite veins at 131±1Ma. 40Ar/39Ar thermochronology on hornblende, muscovite and biotite coupled with available structural data indicates two episodes of deformation (cooling) at ca.135–120Ma and ca. 100–90Ma. The predominant ductile shearing structures, including regional subhorizontal NWW-SEE stretching lineations in the whole Tongbai complex and sinistral and dextral shear senses along its northern and southern boundaries, were formed during the first deformational episode. Regionally, the Cretaceous magmatism, metamorphism, migmatization, deformation and cooling processes in the Tongbai complex are comparable with those in the Dabie–Sulu region, suggesting the evolution of the Tongbai–Dabie–Sulu orogen within the same extensional tectonic regime during this time. The Cretaceous extensional event is thought to have resulted in the lateral eastward extrusion of the Tongbai–Dabie terrene and exhumation and final exposure of the HP/UHP rocks from mid-upper crustal depths. [Copyright &y& Elsevier]