What Happened on Kilauea Volcano About 2,000 Years Ago?

大约 2000 年前基拉韦厄火山发生了什么？

• 批准号: 9526405
• 负责人: John Rhodes
• 金额: $ 3.25万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-01-01 至 1996-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526405&HistoricalAwards=false
• 关键词: What; Happened; Kilauea; Volcano; About

9526405 Rhodes About 2000 years ago there was a profound perturbation in Kilauea's magmatic plumbing system. The effects lasted almost to the present Previous work has shown that, over most of this period, the lavas erupted at or near Kilauea's summit area have ranged in major, trace and isotopic compositions from lavas with the compositional characteristics of historical Kilauea magmas, through intermediate compositions, to lavas that closely resemble Mauna Loa magmas. There are two plausible explanations: either there were short-term changes in the proportions of source components in the Hawaiian plume that supply Kilauea, or magma from Mauna Loa invaded Kilauea' magmatic plumbing system, possibly in response to catastrophic caldera formation and eruption of the Uwekahuna Ash. This project is to complete this work and to test these two contrasting hypotheses. To test these observations, I will systematically sample sequential flows exposed continuously in the 100 m walls of Makaopuhi pit crater. This crater is 13 km down Kilauea's east rift zone from the summit caldera. Within the thick sequence of exposed flows are about 0.5-0.75 ka. Makaopuhi Crater is, therefore, an ideal location to test whether there are flows with anomalous Mauna Loa characteristics (1) that are older than the Uwekahuna Ash, and (2) that are far-removed from the summit caldera. Comprehensive major and trace element data will be obtained on these samples by XRF and INAA to determine their compositional affinities. In addition, Dr. J. P. Lockwood (USGS) and I will attempt to recover charcoal from beneath these flows and the ash layer to provide temporal control by 14C dating. With these questions resolved, we will be in a much better position to evaluate whether or not the Mauna Loa-like flows are a consequence of magmatic invasion from Mauna Loa, or whether there was a major perturbation in the proportions of source components supplying Kilauea from the Hawaiian plume during this period.

大约2000年前，基拉韦厄火山的岩浆管道系统发生了一次深刻的扰动。这种影响几乎一直持续到现在。先前的研究表明，在这一时期的大部分时间里，在基拉韦厄山顶地区或附近喷发的熔岩的主要成分、微量成分和同位素成分各不相同，从具有历史基拉韦厄岩浆成分特征的熔岩，到中间成分的熔岩，再到与莫纳罗亚岩浆非常相似的熔岩。有两种貌似合理的解释：要么是供应基拉韦厄火山的夏威夷火山柱中来源成分的比例发生了短期变化，要么是冒纳罗亚火山的岩浆侵入了基拉韦厄火山的岩浆管道系统，这可能是对灾难性火山口形成和乌韦卡胡纳火山灰喷发的反应。这个项目是为了完成这项工作，并检验这两个相反的假设。为了验证这些观察结果，我将系统地取样连续暴露在Makaopuhi火山口100米长的岩壁中的连续流动。这个火山口位于基拉韦厄火山东部裂谷区13公里处，距离山顶火山口。在厚的暴露流序列中，大约0.5-0.75 ka。因此，Makaopuhi火山口是一个理想的地点，可以测试是否存在具有异常莫纳罗亚特征的流动(1)比Uwekahuna Ash更古老，(2)远离山顶破火山口。利用XRF和INAA对这些样品进行了全面的主微量元素数据分析，以确定其组成亲和力。此外，j·p·洛克伍德博士（美国地质勘探局）和我将尝试从这些流和灰层下面回收木炭，通过14C测年提供时间控制。有了这些问题的解决，我们就能更好地评估类似莫纳罗亚火山的岩浆流是否是莫纳罗亚火山岩浆入侵的结果，或者在这一时期，夏威夷火山羽流中供应基拉韦厄火山的源成分的比例是否发生了重大扰动。