Characteristics of aeolian deposits and evolution of surface process since 15.5 ka in the Zoige Basin, northeastern Tibetan Plateau

Aeolian deposits in the Zoige Basin provide direct evidence for understanding the evolution of the surface environment after the disappearance of the paleolake. The complete aeolian sequence was deposited on the paleo-lakeshore terraces of the Tangke ancient city area. This study focuses on the TKGC section, a representative aeolian deposit on the paleo-lakeshore terrace, and conducts a systematic investigation of its sedimentological, micromorphological, geochemical, and chronological characteristics. The results show that: (1) The chronostratigraphic framework of the TKGC section is as follows: aeolian sand (15.5-13.6 ka BP)- aeolian loess (13.6-8.5 ka BP)-paleosol (8.5-3.0 ka BP)-recent loess (3.0-1.3 ka BP)-topsoil (1.3-0 ka BP). (2) Consistent with previous understandings of global climate change, the loess and paleosol sequences in the alpine Zoige basin also reflect varying intensities of weathering and pedogenesis during different periods. Sedimentological, geochemical, and micromorphological evidence consistently indicate strong pedogenesis during the paleosol development, while pedogenic processes were weak during periods of aeolian sand and loess accumulation. (3) Following the disappearance of the paleolake, from 15.5 to 13.6 ka BP, the region experienced harsh climatic conditions and intense aeolian activity, leading to the deposition of coarse-grained aeolian sand. Around 13.6 ka BP, aeolian activity declined, resulting in the accumulation of finer-grained aeolian loess. By 8.5 ka BP, the regional climate shifted from cold and arid to warm and humid, initiating the development of the paleosol. Around 3.0 ka BP, climatic conditions reverted to colder and drier states, enhancing aeolian processes and facilitating the formation of the recent loess layer. Subsequently, around 1.3 ka BP, the topsoil began to form atop the recent loess deposits.