The Age of the Lower Tuff in the Utaosa Rhyolite, Teragi Cauldron, southwest Japan:Uranium‒lead dating of Late Pliocene zircon using femtosecond laser ablation-inductively coupled multi-collector ICP mass spectrometry
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- Haji Toshiki
- Research Institute of Geology and Geoinformation, Geological Survey of Japan, AIST
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- Kudo Takashi
- Research Institute of Geology and Geoinformation, Geological Survey of Japan, AIST
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- Niki Sota
- Geochemical Research Center, The University of Tokyo
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- Hirata Takafumi
- Geochemical Research Center, The University of Tokyo
Bibliographic Information
- Other Title
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- 照来コールドロン,歌長流紋岩下部凝灰岩の年代:フェムト秒レーザーアブレーション-多重検出器型ICP質量分析法を用いた後期鮮新世ジルコンのウラン-鉛年代測定
Abstract
<p>The Lower Tuff of the Utaosa Rhyolite, the Teragi Group, is a large-scale pyroclastic flow deposit with a volume of ~100 km3. Its eruption formed a volcanic-collapse structure called Teragi Cauldron. In this study, we present new uranium‒lead (U‒Pb) ages of zircons from a sample of welded pumice lapilli tuff from the Lower Tuff to determine the age of the eruption. U‒Pb isotopic data were collected using multiple-collector ICP-mass spectrometry coupled to a femtosecond laser ablation system for precise age determinations. Modified 207Pb method was used to calculate accurate U‒Pb ages with the correction of deviation derived from non-radiogenic lead and initial radioactive disequilibria. The resulting 238U‒206Pb ages of each spot analysis are ranging from 3.3 to 2.7 Ma, with a weighted mean age of 3.03±0.01 Ma (coverage factor k = 2, n = 70, MSWD = 2.6). The mean age overlaps within analytical uncertainties with a previously reported biotite K‒Ar age for the Lower Tuff. Our new U‒Pb age confirms that the caldera-forming eruption occurred at 3.1‒3.0 Ma.</p>
Journal
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- The Journal of the Geological Society of Japan
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The Journal of the Geological Society of Japan 129 (1), 341-354, 2023-06-06
The Geological Society of Japan
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Details 詳細情報について
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- CRID
- 1390577818149383424
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- ISSN
- 13499963
- 00167630
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- Text Lang
- ja
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- Data Source
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- JaLC
- Crossref
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- Abstract License Flag
- Disallowed