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A new method for dating late Quaternary submarine eruptions and its use to investigate magmatic and eruptive processes at island arc volcanoes

一种测定晚第四纪海底喷发年代的新方法及其用于研究岛弧火山岩浆和喷发过程的方法

基本信息

批准号：
20K14586
负责人：
McIntosh Iona
金额：
$ 2.66万
依托单位：
Japan Agency for Marine-Earth Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Early-Career Scientists
财政年份：
2020
资助国家：
日本
起止时间：
2020-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-20K14586/
关键词：
FTIR H2O submarine eruption Izu-Oshima volatiles paleointensity Quaternary Volatiles Submarine eruptions

项目摘要

New samples of submarine basaltic lavas from past ridge eruptions of Izu-Oshima were prepared for volatile analysis by FTIR. These include new pieces from the original rock collection as well as new samples collected by a recent cruise in the area. Samples have been prepared as wafers, as individual glass shards, and as melt inclusions. There is still some difficulty with low volatile concentrations giving large analytical uncertainties for thin samples. This large analytical uncertainty prevents these data being used for estimating eruption age from the change in sea level (eruption pressure) since the time of eruption. FTIR analysis is therefore continuing, with the aim of preparing suitably glassy samples of sufficient thickness for smaller analytical uncertainties. Meanwhile, magnetic paleointensity of a subset of samples has been analysed by collaborator Usui. By combining the magnetic paleointensity and geochemistry data for these samples, it is possible to constrain their eruption ages (without volatile data and sea level estimation, for now). The data suggest relatively young eruption ages, consistent with their stratigraphic relation to onland eruptions of known age. A manuscript on this topic has been submitted and is currently under revision.

从伊豆大岛过去的海脊喷发的海底玄武岩熔岩的新样品制备挥发分FTIR分析。其中包括来自原始岩石收藏的新作品以及最近在该地区巡航收集的新样本。样品已被制备为晶片、单个玻璃碎片和熔体夹杂物。对于薄样品，低挥发性浓度仍有一些困难，会产生较大的分析不确定性。这种巨大的分析不确定性使这些数据无法用于根据自喷发以来海平面（喷发压力）的变化来估计喷发年龄。因此，正在继续进行傅里叶变换红外光谱分析，目的是制备厚度足够的适当玻璃样品，以降低分析的不确定性。与此同时，一个样本子集的磁古强度已经由合作者Alzhei进行了分析。通过结合这些样品的磁性古强度和地球化学数据，有可能限制它们的喷发年龄（目前没有挥发性数据和海平面估计）。这些数据表明，相对年轻的喷发年龄，与他们的地层关系，已知年龄的陆上喷发一致。关于这一专题的手稿已经提交，目前正在修订中。