Zircon U-Pb Ages of Ohno Volcanic Rocks in eastern Kyushu
Zircon U-Pb Ages of Ohno Volcanic Rocks in eastern Kyushu
复制标题
九州东部大野火山岩锆石U-Pb年龄
DOI：
10.5575/geosoc.2017.0003
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Y. Orihashi
中科院分区：
文献类型：
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作者：
H. Shinjoe;Y. Orihashi
九州东部的大野火山岩位于濑户内火山岩的西端。先前报道的大野火山岩的 K-Ar 年龄范围为 10.5 至 15.9 Ma。在这里，我们介绍了大野火山岩中三种长英质岩石的激光烧蚀电感耦合等离子体质谱 (LA-ICP-MS) 锆石 U-Pb 分析结果。我们获得的平均 U-Pb 年龄如下：层序最下层的 Shiraiwasan 火山碎屑流沉积物为 14.71±0.20 Ma (2σ)，小仓凝灰岩为 15.14±0.43 Ma，层序最上层的 Miyakeyama 火山碎屑流沉积物为 14.58±0.21 Ma。我们的结果表明，除了仅以岩脉形式发现的高镁安山岩外，大野火山岩的形成时间比之前认为的要短（约 1 m.y.）。
The Ohno Volcanic Rocks in eastern Kyusyu occur at the western tip of the Setouchi Volcanic Rocks. Previously reported K–Ar ages of the Ohno Volcanic Rocks range from 10.5 to 15.9 Ma. Here we present the results of laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U–Pb analyses of three felsic rocks from the Ohno Volcanic Rocks. We obtained mean U–Pb ages as follows: 14.71±0.20 Ma (2σ) for the Shiraiwasan pyroclastic flow deposit at the lowermost horizon within the sequence, 15.14±0.43 Ma for the Koguraki Tuff, and 14.58 ± 0.21 Ma for the Miyakeyama pyroclastic flow deposit at the uppermost horizon within the sequence. Our results indicate that the Ohno Volcanic Rocks, except for the high-Mg andesite found only as dikes, were formed over a shorter period than previously considered (ca. 1 m.y.).