OSL dating of individual quartz 'supergrains' from the Ancient Middle Palaeolithic site of Cuesta de la Bajada, Spain
OSL dating of individual quartz 'supergrains' from the Ancient Middle Palaeolithic site of Cuesta de la Bajada, Spain
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DOI：
10.1016/j.quageo.2016.07.003
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发表时间：
2016-09-01
影响因子：
2.7
通讯作者：
Perez-Gonzalez, Alfredo
中科院分区：
文献类型：
--
作者：
Arnold, Lee J.;Duval, Mathieu;Perez-Gonzalez, Alfredo
剂量饱和是获得中更新世时间尺度上有限的光释光（OSL）石英年龄的一个基本限制。单颗粒OSL研究通常揭示了在单个颗粒水平上石英剂量饱和特性的显著样品内和样品间变异性。这种增强的可变性可能提供的潜力，以获得扩展范围的年表超过传统的年龄上限的多颗粒光释光测年。然而，在高剂量范围内，对单颗粒OSL特性的详细评估相对较少。在这项研究中，我们探讨了扩展范围的单颗粒光释光测年潜力在Cuesta de la Bajada，在伊比利亚半岛最重要的古代中期旧石器时代遗址之一。该地点的石英样品显示出特殊的剂量饱和特性，含有大量的单个“超颗粒”，具有明亮的OSL信号，非常高的特征饱和剂量（D-0）限值（200至>600戈伊），剂量响应曲线与单饱和指数函数密切一致。OSL信号成分的评估和成功恢复已知的实验室剂量470戈伊的能力，支持获得高当量剂量（D-e）值与合理的拟合不确定性的潜力。一系列新的灵敏度测试被用来评估潜在的偏见超晶粒D-E估计在高剂量范围内有关（i）热传递信号的贡献，（ii）选择的剂量响应曲线拟合函数，和（iii）不足的剂量饱和特性的个别晶粒。使用标准的质量保证标准和新的灵敏度测试获得的单颗粒D-e值是一致的，在2西格玛，并与石英钛中心年龄的三对电子自旋共振（ESR）样品收集的Cuesta de la Bajada上获得的两个协议。这些比较支持我们的单颗粒OSL结果的适用性，并建议可能有很好的潜力，使用石英超颗粒，以建立扩展范围的年表在一些中更新世遗址。与其他单颗粒OSL研究在伊比利亚中部平原的比较表明，有利的剂量饱和特性可能会受到区域尺度的地质控制。合成等分实验的结果也证明了在Cuesta de la Bajada进行单粒OSL测年的重要性，该实验显示，当不合适的谷物类型无意中包含在最终年龄计算中时，多粒年龄偏移为60-170 ka。单颗粒OSL结果表明，Cuesta de la Bajada（单元CB 3）的主要考古层位积累在264 +/- 22和293 +/- 241 a之间。这些年龄与该地区其他重要的旧石器时代早期遗址（Ambrona AS 6和Gran多利纳TD 10）的年代相一致，表明旧石器时代中期古代技术综合体可能至少从海洋同位素阶段9开始遍布伊比利亚。(C)2016爱思唯尔B. V.保留所有权利。
Dose saturation represents a fundamental limitation for obtaining finite optically stimulated luminescence (OSL) quartz ages over Middle Pleistocene timescales. Single-grain OSL studies typically reveal significant intra-and inter-sample variability in quartz dose saturation properties at the individual grain level. This enhanced variability may offer the potential to obtain extended-range chronologies exceeding the traditional upper age limits of multiple-grain OSL dating. However, there have been relatively few detailed assessments of single-grain OSL properties over high dose ranges. In this study we investigate extended-range single-grain OSL dating potential at Cuesta de la Bajada, one of the most important Ancient Middle Palaeolithic sites in the Iberian Peninsula. The quartz samples from this site exhibit exceptional dose saturation properties and contain significant populations of individual 'supergrains' with bright OSL signals, very high characteristic saturation dose (D-0) limits of 200 to >600 Gy, and dose response curves that closely conform to single saturating exponential functions. Assessments of OSL signal composition and the ability to successfully recover a known laboratory dose of 470 Gy support the potential for obtaining high equivalent dose (D-e) values with reasonable fitting uncertainties. A series of novel sensitivity tests are used to assess potential biases in supergrain D-e estimation over high dose ranges related to (i) thermally transferred signal contributions, (ii) choice of dose-response curve fitting function, and (iii) insufficient dose saturation properties of individual grains. The single-grain D-e values obtained using the standard quality assurance criteria and novel sensitivity tests are consistent at 2 sigma, and are in agreement with quartz Ti-centre ages obtained on two of three paired electron spin resonance (ESR) samples collected from Cuesta de la Bajada. These comparisons support the suitability of our single-grain OSL results and suggest there may be good potential for using quartz supergrains to establish extended-range chronologies at some Middle Pleistocene sites. Comparisons with other single grain OSL studies across the Iberian central plains suggest that favourable dose saturation properties may be influenced by regional-scale geological controls. The importance of undertaking single-grain OSL dating at Cuesta de la Bajada is also demonstrated by the results of synthetic aliquot experiments, which reveal multiple-grain age offsets of 60-170 ka when unsuitable grain types are inadvertently included in the final age calculations. The single-grain OSL results indicate that the main archaeological horizon at Cuesta de la Bajada (unit CB3) accumulated between 264 +/- 22 and 293 +/- 241 a. These ages are consistent with the chronologies of other key early Middle Palaeolithic sites in the region (Ambrona AS6 and Gran Dolina TD10) and indicate that the Ancient Middle Palaeolithic techno-complex likely spread across Iberia from at least Marine Isotope Stage 9 onwards. (C) 2016 Elsevier B.V. All rights reserved.