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

9526405罗兹大约2000年前，基拉韦厄的岩浆管道系统发生了深刻的扰动。 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，在基拉韦厄火山顶区或其附近喷发的熔岩，其主要成分、微量成分和同位素成分的范围从具有历史基拉韦厄火山岩浆成分特征的熔岩到与莫纳罗亚火山岩浆非常相似的熔岩。 有两种可能的解释：一种是供给基拉韦厄火山的夏威夷羽流中的源成分比例发生了短期变化，另一种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，这可能是对灾难性的破火山口形成和乌韦卡哈纳火山灰喷发的反应。 本项目旨在完成这项工作，并验证这两个相对的假设。 为了测试这些观测结果，我将系统地对马考普希坑100米长的坑壁中连续暴露的连续流动进行采样。 这个火山口位于基拉韦厄东部裂谷带下方13公里处，距离山顶破火山口。 在厚的暴露流序列中，大约有0.5- 0.75ka。 因此，Makaopuhi火山口是一个理想的位置，可以测试是否有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。 将通过XRF和INAA获得这些样品的全面主要和微量元素数据，以确定其成分亲和力。 此外，美国地质勘探局的洛克伍德博士和我将尝试从这些水流和火山灰层下面回收木炭，以提供14 C测年的时间控制。 有了这些问题的解决，我们将处于一个更好的位置，以评估是否冒纳罗亚山一样的流动是岩浆入侵的后果，从冒纳罗亚山，或是否有一个重大的扰动源成分的比例供应基拉韦厄从夏威夷羽在此期间。

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.