2021年
Characteristics in trace elements compositions of tephras (B-Tm and To-a) for identification tools
GEOCHEMICAL JOURNAL
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- 巻
- 55
- 号
- 3
- 開始ページ
- 117
- 終了ページ
- 133
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.2343/geochemj.2.0619
- 出版者・発行元
- GEOCHEMICAL SOC JAPAN
The absolute date of the Millennium Eruption (ME) of Changbaishan Volcano is widely recognized as AD 946. The Baegdusan-Tomakomai (B-Tm) tephra dispersed during the ME is a robust-age key bed. In order to identify the tephra, refractive index and major- element compositions of volcanic glass shards are conventionally used. Meanwhile, traceelement analysis using the inductively coupled plasma mass spectrometry (ICP- MS) technique for the volcanic glass shards and bulk samples of the B- Tm tephra is still limited. Here we give a detailed description of major- and traceelement compositions for the glass shards and bulk sediments of the B-Tm and Towada caldera eruptions (To-a) tephra deposits from the Lake Ogawara sediment core, Tohoku region, northern Japan to identify the tephras. The depth profiles of the major and trace elements show the significant peaks for the K2O and some trace elements (Zn, Rb, Zr, Nb, Sn, Y, La, Ce, Nd, Th, and U) at the B-Tm tephra layer in the Lake Ogawara sediment core, but no peaks of these elements at the Toa tephra layer. High concentrations of the trace elements in the B- Tm tephra layer were observed in individual glass shards as well as in the bulk sediment. These concentrations are highlighted by the elemental abundance pattern normalized by the crustal abundance. The elemental pattern in individual glass shards from other Japanese tephras showed significant differences from those of the B-Tm tephra, especially in REE compositions. The trace-element compositions of the glass shards and bulk sediments show a strong tool for distinguishing the B-Tm tephra from other Japanese tephras.
- リンク情報
- ID情報
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- DOI : 10.2343/geochemj.2.0619
- ISSN : 0016-7002
- eISSN : 1880-5973
- Web of Science ID : WOS:000664288200002