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Study of temporal and spatial variation of Hawaiian plume

夏威夷羽流时空变化研究

基本信息

批准号：
16403009
负责人：
TAGAMI Takahiro
金额：
$ 8.51万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16403009/
关键词：
Hotspot Hawaiian plume unspiked K-Ar method Geochemistry Maui Oahu kauai Hawai 同位体分析 XRF化学分析

项目摘要

Here we summarize below our recent results of unspiked K-Ar dating on rejuvenated lavas from five Hawaiian volcanoes.(1) West Maui (Sherrod et al., in press) : Nine ages for the underlying postshield and 28 for shield stage units range from 1.8-1.3 Ma and 1.3-1.2 Ma, respectively. Therefore, the duration of volcanic quiescence prior to rejuvenation is about 0.6 m.y. at West Maui, much longer than estimated previously.(2) Koolau, Oahu (Ozawa et al., 2005) : New ages, on 41 samples from 32 vents of rejuvenated-stage Honolulu Volcanics and on eight samples of underlying shield-stage Koolau Volcanics show that shield volcanism ended at 2.1 Ma and that rejuvenated volcanism started at 0.8 Ma, resulting in a 1.3 m.y. hiatus in volcanic activity. Two distinct pulses were found for Honolulu volcanism at 0.8-0.35 and 〜0.1 Ma.(3) Kahoolawe (Sano et al., this meeting and submitted) : youngest eruptions left five small deposits of dike-fed cinders and sparse lava flows, which were previously undated but thought part of a rejuvenated stage on the basis of a substantial erosional unconformity. Two samples from the southernmost site and one sample from the next site northward show ages of 1.0 to 1.4 Ma, suggesting a short gap between the postshield and youngest eruptions.(4) Kauai (Sano et al., in prep.) : New ages of 23 samples from rejuvenated Koloa Volcanics range from 0.15 to 3.9 Ma, whereas ages of five samples from late shield-stage Waimea Canyon Basalt are 4.1-4.5 Ma. Hence, the volcanic quiescence before rejuvenation is at most about 0.3 m.y. The Kauai rejuvenated-stage can be divided into at least five eruptive pulses.

在这里，我们总结了以下我们最近的结果，未加标K-Ar测年的再生熔岩从五个夏威夷火山。(1)West Maui（Sherrod等人，9个盾后单元和28个盾阶段单元的年龄分别为1.8- 1.3Ma和1.3- 1.2Ma。因此，火山在复活之前的平静期约为60万年。比之前估计的要长得多(2)Koolau，Ozawa（Ozawa等人，2005年）：新的年龄，从32个喷口的再生阶段檀香山火山和8个样品的基础上盾阶段Koolau火山的41个样本显示，盾火山活动结束于2.1 Ma，再生火山活动开始于0.8 Ma，导致130万年。火山活动的间歇期发现檀香山火山活动在0.8-0.35和0.1 Ma有两个明显的脉冲。(3)Kahoolawe（佐野等人，最年轻的喷发留下了五个小的沉积物，由岩脉喂入的火山灰和稀疏的熔岩流组成，这些沉积物以前没有注明日期，但被认为是基于大量侵蚀不整合的再生阶段的一部分。两个样本从最南端的网站和一个样本从下一个网站向北显示的年龄为1.0至1.4马，这表明一个短的差距后盾和最年轻的爆发。(4)考艾岛（佐野等人，（正在编写中）23个来自再生科洛亚火山岩的新年龄为0.15 ~ 3.9 Ma，而5个来自晚期屏蔽期怀梅阿峡谷玄武岩的新年龄为4.1-4.5 Ma。因此，火山在复活之前的平静期最多约为30万年。考艾岛的再生阶段可以分为至少五个喷发脉冲。