The Permo-Triassic internal source-to-sink systems of central Asian orogenic belt recorded extensional to compressional accretionary orogeny

Abstract

The Central Asian Orogenic Belt (CAOB), an accretionary orogen with components of oroclinal bending locally, underwent complex accretionary-compressional orogenesis and characterized by a series of ranges and basins within its landscape since the Paleozoic. But how did the CAOB’s tectonic history couples with its interior basin evolution remains unclear. Based on detrital zircon U-Pb geochronology, and Lu-Hf isotope analysis, we quantitatively investigate the variations of the source-to-sink system from the Late Permo-Triassic sedimentary rock of the CAOB’s Bogda region and constrain the related tectonic evolution history and geodynamic processes. The results show that the Late Permo-Triassic sediments in the Bogda are mainly derived from the Central Tianshan, followed by the North Tianshan, East Junggar, and internal Bogda basement that launched in the Middle-Late Triassic, implying these surrounding ranges, the Tianshan, East Junggar, and Bogda, successively experienced varied uplift. Combined with the reported igneous age population, interpretation of basinal seismic profiles, and sedimentological stratigraphic frame, our results of the source-to-sink restoration reveal Bogda underwent the evolution process that was from the Early-Middle Permian a back-arc rift basin of strike-slip feature to the Late Permian-Early Triassic a depression basin, and evolved into a strongly compressed foreland basin during the Middle-Late Triassic. The Late Permian-Early Triassic tectonic inversion recorded by the unconformity was a response to the counterclockwise rotation of blocks that was caused by the oroclinal bending of the CAOB collage process, which possibly resulted from long-term effects of the final closure of Paleo-Asian Ocean (PAO) from west to east during the Permo-Triassic. These episodes of the basin and ranges system evolution signify the transition of the CAOB from an extensional accretionary orogeny to a compressional accretionary orogeny.