Late Mesozoic intracontinental deformation and magmatism in the Chinese Tianshan and adjacent areas, Central Asia

Abstract

Abstract The Tianshan Range–Junggar Basin– Kalamaili Range system represents the southwestern Central Asian Orogenic Belt and is a natural laboratory for studying intracontinental deformation processes. Its current topography is a product of the farfield effects of the Cenozoic India-Asia collision. However, the Mesozoic topographic and tectonic evolution of the Tianshan and Kalamaili Ranges and their impacts on the Junggar Basin remain enigmatic due to the scarcity of data. Here, we present a comprehensive synthesis of sedimentological and geochronological data on these ranges and adjacent basins to reconstruct the intracontinental evolution from the Early Jurassic to the Early Cretaceous. Based on field observations and seismic profile analysis, we identified several unconformities within the late Mesozoic strata in the Tianshan Range and the Junggar Basin. Detrital zircon U-Pb dating results for Lower Jurassic to Lower Cretaceous sandstones of the eastern and southern Junggar Basin, with published paleocurrent data, reveal a complex intracontinental topographic evolution. Moreover, tuffaceous gravels and tuff samples yielded weighted mean zircon 206Pb/238U ages of 156.5 ± 3.2 Ma and 156.3 ± 2.2 Ma, respectively, which indicates the presence of contemporary magmatic activity. The deformation and magmatism mentioned above were possibly related to multi-plate convergence in East Asia during the late Mesozoic. This study provides new insights into the late Mesozoic tectonic-magmatic evolution of the Tianshan Range and its adjacent areas.