Luminescence dating of lacustrine sediments from Tangra Yumco (southern Tibetan Plateau) using post‐IR IRSL signals from polymineral grains
Luminescence dating of lacustrine sediments from Tangra Yumco (southern Tibetan Plateau) using post‐IR IRSL signals from polymineral grains
复制标题
DOI：
10.1111/bor.12096
复制
发表时间：
2015-01
期刊：
影响因子：
2.2
通讯作者：
H. Long;T. Haberzettl;S. Tsukamoto;Ji Shen;T. Kasper;G. Daut;Liping Zhu;R. Mäusbacher;M. Frechen-M.
中科院分区：
文献类型：
--
作者：
H. Long;T. Haberzettl;S. Tsukamoto;Ji Shen;T. Kasper;G. Daut;Liping Zhu;R. Mäusbacher;M. Frechen-M.
大块有机质的放射性碳测年是为青藏高原古气候重建建立湖泊沉积年代学最常用的方法。然而，这种方法可能存在问题，因为过时的材料经常受到旧碳污染。最近，基于发光的年代学技术的进步为湖泊沉积物的年代测定提供了新的选择。在当前的研究中，我们首次测试了一种新的后红外IRSL（pIRIR）测量方案对青藏高原南部当格拉雍错中部深湖沉积物岩心中细粒多矿物材料年代测定的适用性。我们的结果表明：（i）在所研究的湖泊沉积物中观察到铀衰变链中的放射性不平衡，因此使用动态建模方法将其考虑到剂量率计算； (ii) 在 150°C (pIRIR150) 下测量的 pIRIR 方案对我们样品的适用性和稳健性通过一系列发光特性测试以及与独立年龄对照的一致性得到证实； (iii) 浊积岩沉积部分导致发光信号重置不充分，从而导致发光测年明显高估； (iv) 与基于发光的年龄深度模型相比，所研究岩心的大块有机质的 14C 年龄通常产生约 2 ka 的年龄差异，这归因于 Tangra Yumco 的硬水储层效应。这项研究强调了对青藏高原湖泊沉积档案进行多重测年方法的必要性。
Radiocarbon dating of bulk organic matter is the most commonly used method for establishing chronologies of lake sediments for palaeoclimate reconstructions on the Tibetan Plateau. However, this method is likely to be problematic because the dated material often suffers from old carbon contamination. Recently, advances in luminescence‐based chronological techniques have provided new options for dating lacustrine sediments. In the current study, we tested for the first time the applicability of a new post‐IR IRSL (pIRIR) measurement protocol for dating fine‐grained polymineral material from a deep‐lake sediment core from the central part of Tangra Yumco, on the southern Tibetan Plateau. Our results show that: (i) radioactive disequilibria in the uranium decay chain were observed in the studied lake sediments, and thus taken into account for dose rate calculation by using a dynamic modelling approach; (ii) the suitability and robustness of the pIRIR protocol measured at 150°C (pIRIR150) for our samples are confirmed by a set of luminescence characteristic tests as well as the agreement with an independent age control; (iii) turbidite deposition partly caused an insufficient resetting of luminescence signals and thus apparent overestimation in luminescence dating; (iv) compared with the luminescence‐based age‐depth model, the 14C ages of bulk organic matter from the studied core generally yielded an age difference of ∼2 ka, which is attributed to hardwater reservoir effects in Tangra Yumco. This study highlights the need for multi‐dating approaches of lake sedimentary archives on the Tibetan Plateau.