Dating of young (<1 Ma) geological events has long been a challenge for geochronologists. Combining (U‐Th)/He with U‐Pb or U‐Th‐disequilibrium dating methods offers a unique dating tool that can address this important period. We present a new methodology that combines U‐Pb LA‐ICP‐MS and (U‐Th)/He dating of zircon and use it to date two Pleistocene marker tephras (A1Pm and DPm) from the Omachi Tephra suite (Japan). A1Pm and DPm yield U‐Pb ages in the range of 350–850 and ~140–630 ka, respectively, documenting protracted periods of zircon crystallisation (100's of k.y.) prior to eruption. (U‐Th)/He ages constrain the eruption ages of the A1Pm and DPm tephras to 375 ± 13 and 97.1 ± 7.3 ka, respectively, and are in agreement with published estimates. This study demonstrates the potential of combined zircon U‐Pb LA‐ICP‐MS and (U‐Th)/He dating to constrain magmatic and eruption events in the critical ~100 ka–1 Ma interval.

中文翻译：

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结合U‐Pb LA‐ICP‐MS和锆石的（U‐Th）/ He年代来确定晚第四纪事件：以Omachi Tephra套件为例（日本中部）

年轻的（<1 Ma）地质事件的约会一直是地球学家所面临的挑战。（U-Th）/ He与U-Pb或U-Th-不平衡约会方法结合使用可提供一种独特的约会工具，可以解决这一重要时期。我们提出了一种结合U‐Pb LA‐ICP‐MS和（U‐Th）/ He锆石定年法的新方法，并使用它来对Omachi Tephra套件（日本）中的两个更新世标记特非拉斯（A1Pm和DPm）进行约会。A1Pm和DPm产生的U-Pb年龄分别在350–850和〜140–630 ka之间，记录了喷发前锆石结晶的延长时期（ky的100年代）。（U‐Th）/ He年龄将A1Pm和DPm特弗拉斯的喷发年龄分别限制在375±13和97.1±7.3 ka，与公开的估计一致。