Cryptotephras: the revolution in correlation and precision dating.
Cryptotephras: the revolution in correlation and precision dating.
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DOI：
10.1002/jqs.2766
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发表时间：
2015-02
影响因子：
2.3
通讯作者：
Davies SM
中科院分区：
文献类型：
--
作者：
Davies SM
火山灰年代学起源于冰岛，研究可见火山灰层位，20世纪80年代末，火山灰年代学迈出了引人注目的一步，发现了一个约100万年前的火山灰层。苏格兰泥炭沼泽中4300年前的微观灰层。从那时起，在偏远地区寻找这些隐石矿床的努力就越来越强。事实上，最近的一项发现证明了阿拉斯加火山爆发产生的一些细粒玻璃碎片是如何散布到7000多公里外的北方欧洲的。地球化学性质不同的火山灰瞬间沉积在如此大的地理区域，产生了一个强大的相关工具，具有解决一系列科学问题的巨大潜力。这项工作的先决条件是建立区域火山灰年代学框架，其中包括每个存款的约束良好的年龄估计和强大的地球化学特征。随着远地点揭示了以前未知的火山事件的复杂记录，框架定期修订，很明显，一些时间紧的火山爆发具有相似的地球化学特征。因此，寻找独特而强大的地球化学指纹取决于电子探针和激光烧蚀电感耦合等离子体质谱法的严格分析。本文介绍了灰岩年代学和隐灰岩年代学在过去50年中的历史发展和重大突破。
From its Icelandic origins in the study of visible tephra horizons, tephrochronology took a remarkable step in the late 1980 s with the discovery of a ca. 4300-year-old microscopic ash layer in a Scottish peat bog. Since then, the search for these cryptotephra deposits in distal areas has gone from strength to strength. Indeed, a recent discovery demonstrates how a few fine-grained glass shards from an Alaskan eruption have been dispersed more than 7000 km to northern Europe. Instantaneous deposition of geochemically distinct volcanic ash over such large geographical areas gives rise to a powerful correlation tool with considerable potential for addressing a range of scientific questions. A prerequisite of this work is the establishment of regional tephrochronological frameworks that include well-constrained age estimates and robust geochemical signatures for each deposit. With distal sites revealing a complex record of previously unknown volcanic events, frameworks are regularly revised, and it has become apparent that some closely timed eruptions have similar geochemical signatures. The search for unique and robust geochemical fingerprints thus hinges on rigorous analysis by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry. Historical developments and significant breakthroughs are presented to chart the revolution in correlation and precision dating over the last 50 years using tephrochronology and cryptotephrochronology.