Dating glacier ice of the last millennium by quantum technology
Dating glacier ice of the last millennium by quantum technology
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DOI：
10.1073/pnas.1816468116
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发表时间：
2019-04-30
影响因子：
11.1
通讯作者：
Oberthaler, Markus K.
中科院分区：
文献类型：
--
作者：
Feng, Zhongyi;Bohleber, Pascal;Oberthaler, Markus K.
Ar-39 辐射测年涵盖了独特的时间跨度，为解释上个千年的环境档案提供了关键进展。尽管这种示踪剂已被认可数十年，但迄今为止的研究仍受到低丰度和放射性的限制，因此需要大量样本。原子陷阱痕量分析是激光冷却和捕获等量子物理学技术的应用，与传统技术相比，我们可以将样品体积减少几个数量级。在此，我们通过氩阱痕量分析 (ArTTA) 演示高山冰川冰年代测定的整个过程链，表明该方法对 39Ar 的适应现已可用于冰川学应用。小至几公斤的冰块就足够了，并且已在两个人工冰川洞穴中获得。重要的是，这两个地点都可以直接访问冰川底部的地层，并根据现有的年龄限制进行验证。在之前的一项研究中，在 Chli Titlis 冰川海拔 3,030 米（瑞士阿尔卑斯山）获得的冰块已通过最先进的微放射性碳分析进行了年代测定。在 Schaufelferner 冰川海拔 2,870 米（奥地利斯图拜阿尔卑斯山）的冰层中独特地发现了树皮碎片和落叶松针，这使得传统的放射性碳测年成为可能。在这两个地点，基于放射性碳测年和目视地层学的现有年龄信息证实了 39Ar 年龄。根据我们的结果，我们将氩气陷阱痕量分析确定为破译上个千年迄今尚未开发的冰川档案的关键。
Radiometric dating with Ar-39 covers a unique time span and offers key advances in interpreting environmental archives of the last millennium. Although this tracer has been acknowledged for decades, studies so far have been limited by the low abundance and radioactivity, thus requiring huge sample sizes. Atom trap trace analysis, an application of techniques from quantum physics such as laser cooling and trapping, allows us to reduce the sample volume by several orders of magnitude compared with conventional techniques. Here we show that the adaptation of this method to 39Ar is now available for glaciological applications, by demonstrating the entire process chain for dating of alpine glacier ice by argon trap trace analysis (ArTTA). Ice blocks as small as a few kilograms are sufficient and have been obtained at two artificial glacier caves. Importantly, both sites offer direct access to the stratigraphy at the glacier base and validation against existing age constraints. The ice blocks obtained at Chli Titlis glacier at 3,030 m asl (Swiss Alps) have been dated by state-of-the-art microradiocarbon analysis in a previous study. The unique finding of a bark fragment and a larch needle within the ice of Schaufelferner glacier at 2,870 m asl (Stubai Alps, Austria) allows for conventional radiocarbon dating. At both sites the existing age information based on radiocarbon dating and visual stratigraphy corroborates the 39Ar ages. With our results, we establish argon trap trace analysis as the key to decipher so far untapped glacier archives of the last millennium.