Alluvial terrace systems in Zhangjiajie of northwest Hunan, China: Implications for climatic change, tectonic uplift and geomorphic evolution

Abstract: This paper reports the latest details from two comprehensive investigations of alluvial terrace sequences in Zhangjiajie, northwest Hunan Province, China. Seven alluvial terrace units along the Maoxi River and four terrace sequences along the Suoxi River record significant regional geomorphic history. Rates of regional Quaternary uplift and climate change are reconstructed using topographic and stratigraphic evidence from terrace and adjacent cave deposits, along with Electron Spin Resonance (ESR) and Thermo-luminescence (TL) dating controls. Between 928ka and 689ka the time-averaged uplift rate (or incision rate) was 0.16m/ka. The rate decreased to 0.05m/ka between 689ka and 347ka, and then increased slightly to 0.11–0.14m/ka after 347ka. The inferred incision rate increased roughly from 0.21–0.32m/ka to 0.51m/ka from the Late Pleistocene to present. The seven alluvial phases (T7 −T1) and their associated chronology are consistent with climatic variations at regional and/or global scales, suggesting that these terraces represent climate-driven pauses imprinted atop the record of long-term tectonically induced incision by rivers. Insights from these alluvial terrace staircases and cave features indicate that the spectacular sandstone peak forest landscape of the study area has emerged since the middle period of the Middle Pleistocene. [Copyright &y& Elsevier]