Late Cenozoic sedimentary records of the uplift of the Karlik Mountain and aridification of the Hami Basin, central Asia

The Karlik Mountain, at the extreme easternmost Tianshan, marks the terminus of the modern Central Asian Orogenic Belt and serves as a natural laboratory for exploring how strain spreads from the margins of the Eurasian plate to its interior. This study investigates Cenozoic strata, including Oligocene-Miocene Taoshuyuanzi Formation and Pliocene Putaogou Formation, in the Hami Basin through detailed facies analysis, detrital zircon U-Pb geochronology, and magnetic susceptibility to reconstruct the Cenozoic mountain-building history and climate variation of the easternmost Tianshan. Provenance analysis indicates that the Cenozoic sediments were derived from the north and can thus be used to reflect the mountain-building processes of the Karlik Mountain. Facies analysis shows that the Taoshuyuanzi Formation began with fan delta deposits at the lake margin, followed by lacustrine deposits, while the Putaogou Formation is dominated by alluvial fan deposits. The synchronization with intense aridification, as revealed by sedimentary features, allows us to propose that the coarse-grained alluvial deposition in the Putaogou Formation of the Hami Basin marks the Pliocene uplift of the Karlik Mountain. The magnetic susceptibility increased dramatically in the Pliocene, with the trend correlating well with that of the lithology coarsening. The tectonic uplift of easternmost Tianshan, along with the subsequent extreme aridity associated with the global cooling and orogenic barrier, facilitated the preservation of magnetite, leading to the accumulation of alluvial deposits with increased magnetic susceptibility during the Pliocene.