Study on the identification of Quaternary tephras in southern Kyushu based on EPMA analysis

基于EPMA分析的九州南部第四纪火山灰鉴定研究

基本信息

批准号：
15500687
负责人：
MORIWAKI Hiroshi
金额：
$ 2.18万
依托单位：
Kagoshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

This study airas to characterize Quaternary tephras in southern Kyushu based on the chemical compositions of their volcanic glass shards using EPMA, and to get fundamental data on the correlation and chronology of those tephras. In this study, I focused on the late Pleistocene and Holocene tephras of Satsunan Islands including Tokara islands, in which there have been few systematic tephrochronological studies. EPMA analysis made it clear the chemical properties of large plinian tephras in Kuchierabujima, Kuchinoshima and Akusekijima Islands of Tokara Islands, and of middle Pleistocene marker tephras in Yakushioma Island.In addition, Landform evolution and palaeo-environment history were clarified based on the identification and chronolog on other tephras relevant to tephra characterizations of those tephras. The main results are as follows. Three marker pumice falls recognized in Kuchierabujima, Kuchinoshima, Akusekijima Islands, can be distinguished based on their chemical properties. Those tephras rich in Si02 are all rhyolitic and the products of big plinian eruptions, suggesting that those tephras are distributed over Satsunan Islands, Osumi and Satsuma peninsulas far distant from the volcanic islands. Middle Pleistocene vitric ash-Anbo tephra-and gigantic pyroclastic flow-Koseda pyroclastic flow-in Yakushima Island have distinct chemical properties in their glass shards, suggesting that those tephras can be identified in extensive area across and around the Japanese Island.

这项研究的AIRAS是根据使用EPMA的火山玻璃碎片的化学成分来表征九州南部的第四纪tephras，并获取有关这些tephras的相关性和年表的基本数据。在这项研究中，我专注于卫星群岛（包括托卡拉群岛）的晚更新世和全新世te虫，其中很少有系统性的tephrounologologicy研究。 EPMA分析清楚地清楚了库吉埃拉布吉玛，库奇尼岛和托卡拉群岛的阿库塞基岛群岛，以及Yakushioma岛的中更新世标记Tephras的化学性质。那些tephras。主要结果如下。可以根据其化学特性来区分三个标记浮游瀑布，库奇尼岛的库奇拉布吉玛，库奇尼岛，阿库西岛群岛。那些富含SI02的tephras都是流纹岩和大普林尼爆发的产物，这表明那些tephras分布在萨特索南群岛，奥苏马和萨特苏马半岛上，远离火山群岛。中更新世的烟灰和巨大的火山碎屑流动性山形型流动Yakushima岛的玻璃碎片中具有独特的化学特性，这表明这些Tephras可以在日本岛上及其周围的广阔区域中识别出来。