Late Quaternary paleoclimatic and geomorphological evolution at the interface between the Menyuan basin and the Qilian Mountains, northeastern Tibetan Plateau

Abstract

The Tibetan Plateau is regarded as an amplifier and driver of environmental change in adjacent regions because of its extent and high altitude. However, reliable age control for paleoenvironmental information on the plateau is limited. OSL appears to be a valid method to constrain the age of deposits of glacial and fluvial origin, soils and periglacial structures in the Menyuan basin on the northeastern Tibetan Plateau. Dating results show glaciers advanced extensively to the foot of the Qilian mountains at~21 ka, in agreement with the timing of the global Last Glacial Maximum (LGM) recorded in Northern Hemisphere ice cores. Comparison with results from the eastern Tibetan Plateau suggests that the factor controlling glacial advance in both regions was decreased temperature, not monsoon-related precipitation increase. The areas of the Menyuan basin occupied by glacio-fluvial deposits experienced continuous permafrost during the LGM, indicated by large cryoturbation features, interpreted to indicate that the mean annual temperature was ≥7°C lower than at present. Glacio-fluvial systems in the Menyuan basin aggraded and terraces formed during cold periods (penultimate glaciation, LGM, and possibly the Younger Dryas) as a response to increased glacial sediment production and meltwater runoff then.

Climate-dependent fluvial architecture and processes on a suborbital timescale in areas of rapid tectonic uplift: An example from the NE Tibetan Plateau

“…Furthermore, an ice-rafted origin is in agreement with the deposition of units U1 during cold periods. In addition, Wang et al (2013) argue that the coarse-grained fluvial deposits (T2, T3, T4, T5, T6 and T7) and periods of fluvial deposition (at top) with climatic evolution recorded by the grain-size record of loess deposits at GL (gray) and YZ (red) (Lu et al, 2004b) in the NETP (locations in Fig. 1B).…”

“…For example, mean annual temperature during the LGM was 7-9°°C lower than at present, which caused extensive glacier expansion (Wang et al, 2013). Thus, the river catchments in the region are highly suited for studying the coupled impact of tectonic movements and climate changes on fluvial morphological development and the sedimentary architecture of fluvial deposits.…”

River terraces as a response to climatic forcing: Formation processes, sedimentary characteristics and sites for human occupation

“…It is followed by downcutting due to increased snow-and ice-melt at deglaciation under stable or decreasing sediment supply, as shown by field measurements (Marren and Toomath, 2013). However, a similar system is also present in periglacial-temperate alternations largely due to the effect of re-appearance of vegetation on a bare landscape (Vandenberghe et al, 1984;Vandenberghe, 1993aVandenberghe, , 1995a, and similarly in monsoonal and (sub-)tropical environments (Bridgland and Westaway, 2008;Vandenberghe et al, 2011;Wang et al, 2013;Pan et al 2010). However, the exact timing of the incision event may be slightly different in those different climatic zones (Starkel et al, 2007).…”

Late Quaternary glacial advances in the eastern Qilianshan, north‐eastern Tibet, as inferred from luminescence dating of fluvioglacial sediments

“…The OSL age of 19 ± 1 ka from Wang et al . () was determined using average D e values on small aliquots. The authors considered that the samples were well bleached at the time of deposition based on normal D e distribution.…”

“…A blue‐filled circle shows an OSL age after Wang et al . (), with the other OSL ages from this study (see also online Supplementary Material).…”