The impact of faulting-induced uplift and subsidence on terrace formation and abandonment: A case study of the Huangshui River, NE Tibetan Plateau

Fluvial terraces are important archives for inferring changes in river dynamics. In the northeastern Tibetan Plateau (NETP), the Huangshui River flows through broad depressions and narrow gorges. This morphology is the result of strike-slip- and reverse-faulting. The differential vertical motions cause the formation of diverse fluvial terraces. Morphological analyses, sedimentary successions, and optically stimulated luminescence (OSL) dating are used to map, characterize, and date fluvial terraces in two depressions and the connecting gorge. Our results show that an important phase of tectonism occurred shortly after 138 ka, because: (1) Terraces older than 138 ka in the gorge show clear deformation in their longitudinal profiles; (2) Terraces from the last interglacial are composed of a thick fill terrace in the upstream depression, a strath terrace in the gorge, and a fill terrace created by an alluvial fan in the downstream depression; (3) The aggradation of the last interglacial terrace began synchronously in the upstream and downstream depression, while the abandonment age becomes younger in an upstream direction (from c. 131 ka to c. 91 ka). The transient abandonment reflects an upstream migrating knickpoint. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change