Mantle controls on magmatic-volcanic cycles at basaltic volcanoes: An isotopic probe of the Pu'u 'O'o, Halema'uma'u, and 2018 Leilani eruptions of Kilauea Volcano

地幔对玄武岩火山岩浆-火山循环的控制：对 Puu Oo、Halemaumau 和 2018 年基拉韦厄火山 Leilani 喷发的同位素探测

基本信息

批准号：
2011366
负责人：
Aaron Pietruszka
金额：
$ 40万
依托单位：
University of Hawaii
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011366&HistoricalAwards=false
关键词：
Mantle controls magmatic volcanic cycles

项目摘要

The spectacular 2018 Leilani rift eruption of Kilauea Volcano captivated the attention of nightly news-watchers and internet-surfers around the U.S. and the world, and it became a destructive volcanic crisis for residents of the Island of Hawaii. The volcanic events of 2018 included the end of two sustained lava eruptions at Kilauea, a large (magnitude 6.9) local earthquake, and a voluminous (~0.8 km3) explosive collapse of the volcano’s summit region that damaged roads and infrastructure in Hawaii Volcanoes National Park. Over three months in 2018, a large amount of new lava (0.8 km3) erupted from fissures on Kilauea’s Lower East Rift Zone at Leilani Estates and destroyed ~700 homes. The scale of this eruption (i.e., its high effusion rate and level of destruction) was “truly unprecedented in the modern record” according to Tina Neal, the Scientist-in-Charge at the Hawaiian Volcano Observatory of the U.S. Geological Survey. Very little is yet known about the magmatic processes that controlled the volcanic events of 2018. In this study, the temporal changes in the composition of lava samples from three Kilauea eruptions, each separated by ~20 km, will be used to track the movement of magma batches through the volcano’s plumbing system as a function of time and space. These results will be used to test the hypothesis that the 2018 Leilani rift eruption was actively driven by the delivery of at least one large mantle-derived magma batch to a volcanic edifice that already held an unusually large amount of stored magma. This research has the potential to reveal the enigmatic mantle controls on the behavior and hazards of Kilauea Volcano. An educational module, simulating the volcanic events at Kilauea in 2018 through role playing, will be created and published on the Science Education Resource Center (SERC) website for Hawaiian Volcanoes and Hazards Education as an integral part of this study.Kilauea experiences long-term cycles of dominantly effusive vs. explosive volcanic activity on a time scale of decades to centuries, with the latter often associated with summit collapse and/or caldera formation. The events of 2018 likely mark the culmination of a volcanic cycle at Kilauea. Lavas from this volcano display systematic chemical (e.g., Nb/Y) and isotopic (e.g., 206Pb/204Pb) variations on time scales of years to centuries due to its mantle source heterogeneity and melting processes. These mantle-derived changes in parental magma composition indicate that Kilauea also experiences distinctive magmatic cycles, some of which coincide with the long-term volcanic cycles. An important project goal is to test the idea that the long-term volcanic cycles at Kilauea are ultimately driven by mantle processes, including (1) the generation of compositionally distinct magma batches within the heterogeneous mantle and (2) the transport of these magma batches from the source to the surface. Kilauea’s magmatic-volcanic cycles may be caused by two mechanisms. One mechanism—essentially passive—is related to a refractory mantle source-related decrease in the degree of partial melting, a decline in the magma supply rate, and a subsequent disruption of the summit magmatic plumbing system. This was important for the previous magmatic-volcanic cycle that ended with summit collapse and an explosive eruption in 1924. The other mechanism—actively driven—is related to high degrees of partial melting of a more fertile mantle source, a high rate of magma supply, and the vigorous delivery of one or more large magma batches from the mantle. This hypothesis for the events of 2018 will be tested using the chemistry and Pb, Sr, and Nd isotope ratios of lava samples from (1) the 2018 Leilani rift eruption, and (2) the final decade of the long-lived Pu’u ’O’o rift eruption (1983-2018) and summit lava lake within Halema’uma’u Crater (2008-2018).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

2018 年基拉韦厄火山壮观的莱拉尼裂谷喷发吸引了美国和世界各地晚间新闻观察者和互联网浏览者的关注，它对夏威夷大岛的居民造成了一场毁灭性的火山危机。 2018 年的火山事件包括：基拉韦厄两次持续的熔岩喷发结束，当地发生了一场大地震（里氏 6.9 级），火山山顶区域发生大量爆炸性塌陷（约 0.8 平方公里），损坏了夏威夷火山国家公园的道路和基础设施。 2018 年的三个多月里，大量新熔岩（0.8 平方公里）从基拉韦厄东部裂谷区的裂缝中喷发。 Leilani 庄园并被摧毁了约 700 所房屋，这次喷发的规模（即其高喷发率和破坏程度）为美国地质调查局夏威夷火山观测站负责人蒂娜·尼尔 (Tina Neal) 表示，“这在现代记录中确实是史无前例的”。我们对控制 2018 年火山事件的岩浆过程知之甚少。，来自三次基拉韦厄火山喷发的熔岩样本成分的时间变化，每次喷发相距约 20 公里，将用于跟踪岩浆批次在火山中的运动这些结果将用于检验以下假设：2018 年的莱拉尼裂谷喷发是由至少一批来自地幔的岩浆输送到一座已经拥有异常火山岩的火山大厦所驱动的。这项研究有可能揭示神秘的地幔对基拉韦厄火山的行为和危害的控制。模拟火山事件。 2018 年的基拉韦厄火山将通过角色扮演的方式创建并在科学教育资源中心 (SERC) 网站上发布，以进行夏威夷火山和灾害教育，作为本研究的一个组成部分。基拉韦厄火山经历了喷发性火山活动与爆发性火山活动的长期循环在数十年到数百年的时间范围内，后者通常与山顶塌陷和/或火山口的形成有关。2018 年的事件可能标志着火山的顶峰。由于其地幔来源的异质性和这些由地幔引起的变化，该火山的熔岩在数年至数世纪的时间尺度上表现出系统的化学（例如，Nb/Y）和同位素（例如，206Pb/204Pb）变化。母体岩浆成分表明基拉韦厄也经历了独特的岩浆循环，其中一些与长期火山循环一致。一个重要的项目目标是测试认为基拉韦厄的长期火山循环最终是由地幔过程驱动的，包括（1）在异质地幔内产生成分不同的岩浆批次，以及（2）这些岩浆批次从基拉韦厄的源头迁移到地表。岩浆-火山循环可能由两种机制引起，一种机制本质上是被动的，与难熔地幔源相关的部分熔融程度的降低，即岩浆供应的减少有关。速率，以及随后对山顶岩浆管道系统的破坏，这对于之前的岩浆-火山循环非常重要，该循环以山顶塌陷和 1924 年的爆发性喷发而告终。另一种机制（主动驱动）与高度部分熔融有关。更肥沃的地幔来源、高岩浆供应率以及从地幔中大量输送的一批或多批岩浆将使用化学和化学方法进行检验。 (1) 2018 年 Leilani 裂谷喷发，以及 (2) 长寿 Pu'u 'O'o 裂谷喷发的最后十年 (1983-2018) 和山顶熔岩的熔岩样本的 Pb、Sr 和 Nd 同位素比率Halema'uma'u 陨石坑内的湖泊（2008-2018）。该奖项反映了 NSF 的法定使命，并被认为值得通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。