The Qaidam Basin preserves the largest Yardang field on Earth, and yardangs are intriguing landforms for studies of the paleo-environment and aeolian processes. Formation of yardangs involved both the initial lacustrine deposition and the subsequent wind-erosion processes. However, the timings of both processes in the Qaidam Basin are still controversial due to limited age data and unsuitable dating methodology. In this paper, we first compared two optical dating methods to determine the suitable one for the study area, then investigated the geomorphic processes based on the new ages. Two-step post-IR IRSL (pIRIR) and multi-elevated-temperature pIRIR (MET-pIRIR) methods of feldspar, were applied to date lacustrine sediments on the top parts of yardangs to decipher the transition time from depositional to an erosional environment. Comparisons of the two methods demonstrated that the influence from anomalous fading was very minimal thus negligible for MET-pIRIR method, as proved by the De plateau between MET-pIRIR₂₅₀ and MET-pIRIR₂₉₀; while the pIR50IR₂₅₀ signals suffered from fading obviously, which was difficult to be corrected due to the high De close to saturation. Consequently, the chronology in this study was based on the MET-pIRIR₂₅₀ method, potentially offering reliable ages of over 200 ka. Seven MET-pIRIR₂₅₀ ages of 201–336 ka suggested that a mega-Qaidam Lake (>2714 m a.s.l. on Google Earth) maintained until Marine Isotopic Stage (MIS) 7. The absence of sediments since ca. 200 ka implied wind-erosion and yardang formation since MIS6. This transition from lacustrine to a wind-erosion environment was interpreted as a response to the glacial-interglacial scale climatic changes.

中文翻译：

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青藏高原柴达木盆地亚当邦古湖相沉积物的IR-IRSL后年代学

柴达木盆地保留了地球上最大的Yardang油田，而yardangs是研究古环境和风成过程的有趣地形。yardangs的形成涉及最初的湖相沉积和随后的风蚀过程。但是，由于年龄数据有限和不合适的年代学方法，柴达木盆地这两个过程的时间安排仍存在争议。在本文中，我们首先比较了两种光学测年方法，以确定适合该研究区域的光学测年方法，然后研究了基于新时代的地貌过程。长石的两步后IR IRSL（pIRIR）和多温pIRIR（MET-pIRIR）方法被用于对yardangs顶部的湖相沉积物进行测年，以解释从沉积到侵蚀环境的过渡时间。₂₅₀和MET-pIRIR ₂₉₀；而pIR50IR ₂₅₀信号明显衰减，由于接近饱和的高De难以校正。因此，本研究中的年代学基于MET-pIRIR ₂₅₀方法，可能提供超过200 ka的可靠年龄。七MET-pIRIR ₂₅₀岁的201-336 KA建议保持到海洋同位素阶段（MIS）7.由于缺少沉积物的大型柴达木湖（>谷歌地球2714米ASL）CA。自MIS6起，200 ka隐含了风蚀和yardang的形成。从湖相到风蚀环境的这种转变被解释为对冰川-冰川间规模气候变化的响应。