Uncovering Hotspot Volcanism: Mantle Melting, Magmatic Plumbing, Explosive Eruptions and Crustal Contamination at Kilauea Volcano, Hawaii

夏威夷的基拉韦厄火山是地球上研究玄武岩火山内部过程的最佳地点之一。基拉韦厄火山喷发频率高，容易获得熔岩，远离板块边界或大陆的中太平洋独特的地质环境，以及对基拉韦厄的广泛知识基础，使我们能够解决与活火山有关的基本问题。我们建议解决的任务和问题是：1）监测基拉韦厄两次喷发的熔岩的岩浆演化，以评估地幔熔融过程和火山的岩浆结构; 2）记录最近熔岩中地壳污染的程度和来源; 3）确定基拉韦厄在过去2200年中的溢出-爆炸循环的控制因素; 4）创建一个教育模块，让学生通过研究活火山来学习科学。夏威夷是对玄武岩火山进行岩石学和地球化学研究的绝佳地点。在NSF的支持下，首席研究员和同事们得以监测当前裂谷喷发熔岩的岩石学和地球化学变化，并目睹这一长期岩浆事件期间熔融过程和地幔源成分的动态变化。我们已发表的工作表明，熔体通过地幔在开放的渠道输送到表面没有显着的汇集和均质化，保存显着的短期（~10年）铅同位素变化。新的山顶喷发（自2008年以来一直在进行）提供了自1982年以来基拉韦厄中央岩浆储存库的第一批样本。这些新的样品表明，2009年有一种地球化学性质独特的幔源岩浆被输送到山顶水库，但截至2012年，它还没有在Pu 'u' O 'o喷发。如果这两次喷发之间的地球化学差异持续存在，它们表明每个喷口都有单独的地幔通道，这与基拉韦厄岩浆系统的当前模型有很大的不同。新的研究表明，爆炸性喷发在基拉韦厄过去的2200年中占据主导地位，地球化学可能是爆炸性喷发的预兆。NSF的资金将用于：1。监测基拉韦厄火山两次喷发的岩浆演化; 2.确定我们在基拉韦厄火山熔岩中观察到的氧同位素变化是否与地壳污染或源区异质性有关; 3.将我们对基拉韦厄岩石的地球化学变化的研究扩展到其爆炸过去的2000年，以确定富集的岩浆是否是爆炸性喷发的标志。我们的地球化学结果已经并将继续与夏威夷火山观测站的实地观测、地球化学和地球物理监测计划相结合，并与其工作人员协商解释。我们评估基拉韦厄岩浆过程的整体方法对于理解这座和其他玄武岩火山如何工作至关重要。

Hawaii's Kilauea Volcano is one of the best places on Earth to study processes within basaltic volcanoes. Its high eruption frequency, easy access to lavas, distinct geologic setting in the central Pacific far from plate boundaries or continents, and the extensive knowledge base on Kilauea allows research us to address fundamental problems related to active volcanoes. The tasks and issues we propose to address are: 1) Monitoring the magmatic evolution of lavas from Kilauea's two ongoing eruptions to evaluate mantle melting processes and the magmatic architecture of the volcano; 2) Documenting the extent and origin of crustal contamination in its recent lavas; 3) Determining the controls of Kilauea's effusive-explosive cycles during the last 2200 years; and 4) Creating an education module to engage students in learning science through studying active volcanoes.Hawaii is a superb location for petrologic and geochemical research on basaltic volcanoes. Prior NSF support has allowed the Principal Investigator and colleagues to monitor the petrologic and geochemical variations of lava from the current rift eruption and to witness the dynamic changes in the melting process and mantle source composition during this long-lasting magmatic event. Our published work has shown that melt is transported through the mantle in open channels to the surface without significant pooling and homogenization, preserving remarkable short-term (~10 years) Pb isotopic variations. The new summit eruption (ongoing since 2008) provided the first samples from Kilauea's central magma storage reservoir since 1982. These new samples indicate a geochemically distinct mantle-derived magma was delivered to the summit reservoir in 2009 that has not yet (as of 2012) erupted at Pu'u 'O'o. If the geochemical differences between these two eruptions persist, they suggest there are separate conduits to the mantle for each vent, a major departure from current models for Kilauea's magmatic system. New studies have shown that explosive eruptions have dominated Kilauea's last 2200 years and that geochemistry may be a harbinger of explosive eruptions. NSF funding will be used to: 1. Monitor the magmatic evolution of Kilauea lavas from its two ongoing eruptions; 2. determine whether the O isotope variations we have observed for Kilauea lavas are related to crustal contamination or source heterogeneity; and 3. extend our study of temporal geochemical variations of Kilauea's rocks ~2000 years into its explosive past to determine whether enriched magmas are indicators of explosive eruptions. Our geochemical results have been and will continued to be integrated with observations from Hawaiian Volcano Observatory's field, geochemical and geophysical monitoring programs, and interpreted in consultation with their staff. Our holistic approach to evaluating magmatic processes at Kilauea is critical for understanding how this and other basaltic volcanoes work.