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Luminescence dating of lacustrine sediments from CUOE Lake on the central Tibetan Plateau
Geochronometria ( IF 0.8 ) Pub Date : 2020-07-22 , DOI: 10.2478/geochr-2020-0002
Yandong Hou 1, 2 , Hao Long 1, 3 , Lei Gao 1 , Ji Shen 1
Affiliation  

Luminescence dating technology has been used for chronological constraints on lacustrine sediments due to the ubiquitous materials (e.g., quartz and feldspar) as dosimeters, and a relatively long dating range, compared with the commonly used radiocarbon dating method. However, quartz dating on the Tibetan Plateau may suffer from dim and unstable luminescence signals. In the current study, we investigate a lake-related outcrop from the shore of Cuoe Lake on the central Tibetan Plateau. Both coarse-grained quartz and K-feldspar fractions were extracted, and OSL and post-IR IRSL signals were measured from these fractions, respectively. Combining the stratigraphy analysis and dating results, this study shows that: (1) quartz appears to be unsuitable for dating because of very dim natural signals and even anomalous fading (average g-value: 4.30 ± 2.51 %/decade). The suitability of the applied pIRIR protocol measured at 150°C (pIRIR150) for K-feldspar samples was confirmed by a set of luminescence tests; (2) compared with the luminescence-based chronology, the 14C age of shells from the same sediment layer yielded older age by ~7 ka, which is likely attributed to hard water reservoir effect in Cuoe Lake; (3) the lake level reached its peak and maintained high-stand during the early Holocene (~9.4–7.1 ka). This study highlights the applicability of K-feldspar luminescence dating when the counterpart quartz OSL is insensitive and encounters anomalous fading.

中文翻译:

青藏高原中部CUOE湖湖相沉积物的发光年代

与放射性碳测年法相比,发光测年技术已被用于对湖泊沉积物进行时间约束,这是由于作为辐射剂量计的材料(例如石英和长石)以及相对较长的测年范围。但是,青藏高原上的石英年代可能会受到暗淡且不稳定的发光信号的影响。在当前的研究中,我们调查了青藏高原中部库埃湖沿岸与湖泊有关的露头。提取了粗粒石英和钾长石馏分,并分别从这些馏分中测量了OSL和IR后IRSL信号。结合地层学分析和测年结果,这项研究表明:(1)石英似乎不适合测年,因为自然信号非常暗淡,甚至异常衰落(平均g值:4.30±2.51%/十年。一组发光测试证实了所应用的pIRIR协议在150°C(pIRIR 150)下对钾长石样品的适用性。(2)与基于发光的年代学相比,来自同一沉积层的壳的14 C年龄产生了约7 ka的更老年龄,这很可能归因于库埃湖中的硬水储层效应;(3)在全新世早期(〜9.4–7.1 ka),湖泊水位达到峰值并维持高水位。这项研究突出了当石英石英OSL不敏感并遇到异常衰落时钾长石发光测年法的适用性。
更新日期:2020-07-27
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