Field-based mapping, sandstone petrology, palaeocurrent measurements and zircon cathodoluminescence images, as well as detrital zircon U–Pb geochronology were integrated to investigate the provenance of the Upper Carboniferous – Upper Triassic sedimentary rocks from the northern Bogda Mountains, and further to constrain their tectonic evolution. Variations in sandstone composition suggest that the Upper Carboniferous – Lower Triassic sediments displayed less sedimentary recycling than the Middle–Upper Triassic sediments. U–Pb isotopic dating using the LA-ICP-MS method on zircons from 12 sandstones exhibited similar zircon U–Pb age distribution patterns with major age groups at 360–320 Ma and 320–300 Ma, and with some grains giving ages of > 541 Ma, 541–360 Ma, 300–250 Ma and 250–200 Ma. Coupled with the compiled palaeocurrent data, the predominant sources were the Late Carboniferous volcanic rocks of the North Tianshan and Palaeozoic magmatic rocks of the Yili–Central Tianshan. There was also input from the Bogda Mountains in Middle–Late Triassic time. The comprehensive geological evidence indicates that the Upper Carboniferous – Lower Permian strata were probably deposited in an extensional context which was related to a rift or post-collision rather than arc-related setting. Conspicuously, the large range of U–Pb ages of the detrital zircons, increased sedimentary lithic fragments, fluvial deposits and contemporaneous Triassic zircon ages argue for a Middle–Late Triassic orogenic movement, which was considered to be the initial uplift of the Bogda Mountains.

The Permian–Triassic successions in the Bogda Mountains, northern Xinjiang, northwest China, record a pivotal but poorly constrained tectonic regime of a transtensional rift, which can be subdivided into syn-rift, post-rift, and uplift stages. Systematic sandstone petrography, whole-rock geochemistry, and detrital-zircon U–Pb dating analysis were conducted to evaluate the source-to-sink process involved, as well as to understand its provenance characteristics and the factors that control the source-to-sink evolution. Comprehensive provenance analytical methods indicate that the sediments in the syn-rift and post-rift stages experienced weak chemical weathering and were compositionally immature, poorly sorted, and mostly acidic, with few basic volcanic rocks from North Tianshan (NTS) and Central Tianshan (CTS). Meanwhile in the uplift stage, the sediments underwent moderate chemical weathering and sedimentary recycling, with a complex age population, containing syn-depositional zircon ages, which were likely derived from the volcanic rocks of NTS, CTS, and the Bogda Mountains. Integrated provenance analyses reveal that the syn-rift and post-rift source-to-sink systems of Bogda rift (and probably other rift basins) are controlled mainly by tectonics, the sinks are principally immature, and the sources are derived predominantly from axial volcanic arcs and local rift shoulders, with little input from syn-depositional volcanic rocks. Inversely, the source-to-sink system of the uplift stage is rather complex, which is influenced by tectonics, climate, and sedimentary processes. Their sinks are relatively submature to mature, and their sources include detritus, with ages close to the depositional age, along with significant input from surrounding volcanic arcs and initial uplift highlands.

The extensively exposed late Carboniferous volcanic and volcaniclastic successions along the northern margin of the North Tianshan are called the Arbasay Formation. We present field-based mapping, petrography, zircon cathodoluminescence (CL) images, and U–Pb dates, as well as whole-rock geochemical data for these rocks, in order to constrain their formation age and petrogenesis, and understand the geodynamic setting. Conspicuously, the Arbasay Formation shows typical basalt–andesite–dacite–rhyolite volcanic series, and is dominated by andesites with a small amount of basalts and rhyolites based on the geological profile. U–Pb isotopic dating using the LA-ICP-MS method on zircons reveals that the volcanic rocks in the Arbasay Formation formed at 308–305 Ma, that is, late Carboniferous, rather than early Permian as previously proposed. Geochemically, the volcanic rocks mainly belong to the calc-alkaline series and have arc-like geochemical compositions. They are enriched in LREEs ((La/Yb)_N = 2.9–7.5) and LILEs (K, Rb, Ba) and depleted in HFSEs (Nb, Ta, Ti). In the tectonic discrimination diagrams, the basalts mainly fall into the area of continental arc. Given our U–Pb dating results, geochemical characteristics, and the regional geological framework, we propose that the late Carboniferous volcanic rocks originated from the arc-related setting, not the intracontinental rift-related setting. They are possibly the major constituents of a continental arc that is formed with the southward subduction of the North Tianshan Oceanic lithosphere.