Wind erosion on the north‐eastern Tibetan Plateau: constraints from OSL and U‐Th dating of playa salt crust in the Qaidam Basin

Abstract

The arid Qaidam Basin is the largest (~3.88 × 104 km2) basin on the north‐eastern Tibetan Plateau. Wind erosion in the area has been regarded as an important trigger for intra‐basin tectonic balance upheaval, geomorphologic development and as a major supplier of dust to the Chinese Loess Plateau downwind. An initial estimate of the rate of wind erosion (Kapp et al., 2011) based on geological cross‐sections has suggested up to 3.2 × 104 km3 of sediments has been deflated over the past 2.8 Ma, lowering the landscape by an average of 0.29 mm/yr. In this paper we re‐evaluate this estimate by dating surface crusts present on three playas within the basin. Understanding the development of these playas is crucial to assessing the overall role of the wind in shaping the regional landscape because they are typically capped with a thick salt crust which effectively protects them from wind erosion. Optically stimulated luminescence (OSL) and U‐series dating from a pit section and from the top of a deep drill core, together with results from magnetostratigraphy and a climate proxy record correlated to the marine oxygen isotope record, are used here to determine the age of the playa plains and suggest that the salt crusts have an age of c. 0.1 Ma. This young age and the wide distribution of resistant thick salt crusts of the playa plains indicate a much lower degree of wind erosion than previously suggested. The crusts protect the surface from significant surface erosion (including sediment exhumation and unloading) and whilst some wind erosion does occur, it is unlikely to be sufficient to trigger tectonic uplift of the basin or to be a major dust source for the Loess Plateau as previously suggested. Copyright © 2013 John Wiley & Sons, Ltd.

Quantifying Wind Erosion During the Late Quaternary in the Qaidam Basin, Central Asia

“…The associated lacustrine and/or fluvial sediments either constitute the main body of (Ding et al, 2019) or cap (this study) the modern yardangs, indicating that these yardangs formed simultaneously with or after the shrinking and disappearance of the lake and/or fluvial systems, which we argue occurred at~105 ka based on the timing of terrace abandonment. This is consistent with the climatic shift to hyperarid conditions at~90-100 ka evidenced by the rapid crystallization of the salt crust in playa plains between yardang fields (Figure 1a; Han et al, 2014].…”

“…The sediments removed by wind are generally Neogene-Quaternary lacustrine sandstone and mudstone, which form numerous migratory dunes within the basin or are redeposited in the more humid eastern QB or the Chinese Loess Plateau farther east Mao & Guo, 2018;Rohrmann et al, 2013;Yu et al, 2015). Estimates of wind erosion rates may reach~1.1 mm/a above anticlinal crests but are negligible in playas due to buffering by thick salt crusts on the surface (Han et al, 2014). The associated erosion rates are spatially variable.…”

Geological Features and Evolution of Yardangs in the Qaidam Basin, Tibetan Plateau (NW China): A Terrestrial Analogue for Mars

“…Since the middle to late Miocene, it has been compressed and actively shortened in the NE‐SW direction due to the ongoing convergence between India and Eurasia plates (Tapponnier et al, ; Wu et al, ; Zhang et al, ), and also NW‐SE and NNW‐SSE trending folds are developed in the sediments of the western basin (Wang, Zheng et al, ; Zhang et al, ). These folds separated the basin into several subbasins sometimes hosting lakes (Fang et al, ; Han et al, ; Wang et al, ; Wang, Fang et al, ).…”

Sr-Nd-Pb Isotopic compositions of the Neogene Eolian Deposits in the Xining Basin and Implications for Their Dust Sources

“…Qaidam Basin, located on the NE QTP, has been thought to be a source region for loess deposits in the CLP (Pullen et al, 2011;Stevens et al, 2010). However, whether the Qaidam Basin is an important source area of the loess in the CLP remains unresolved (Han et al, 2014;Pullen et al, 2011;Sun, 2002).…”