Mantle and Crustal Causes of Compositional Variation in Kilauea Historical Lavas

熔岩提供了与火山有关的地壳和地幔过程的重要线索。基拉韦厄火山是一个理想的自然实验室，用于评估火山内部的物理过程如何导致熔岩成分的可观察变化，它是世界上研究得最好的火山。因此，我们可以从良好约束的角度来解决基本问题。该项目包括进行精确的微量元素和同位素分析，以定量模拟地幔融化过程，评估源非均质性和评估地壳污染对基拉韦厄历史熔岩组成的影响。我们将对历史基拉韦厄火山熔岩进行全面的岩石学和地球化学表征，包括正在进行的Puu Oo火山喷发的熔岩。我们记录了其历史顶峰熔岩（约200年）的长期、系统的同位素和成分变化以及Puu Oo裂谷带持续喷发（17年以上）的短期地球化学变化。Puu Oo和其他主要裂谷带喷发的岩浆被认为绕过了山顶储层，这让我们更清楚地了解了地幔融化过程和来源的非均质性。洋岛玄武岩氧同位素比值低于洋中脊玄武岩的原因仍有争议。一些研究将这些差异与不同的地幔来源联系起来，而另一些研究则援引地壳污染。我们记录了一些基拉韦厄火山历史熔岩中广泛的地壳污染的证据，包括那些来自Puu Oo火山喷发的熔岩，但尚未确定基拉韦厄火山来源的氧同位素值。新技术将用于确定正在喷发的样品的氧同位素，其他历史熔岩和3公里深的地热井的热液蚀变岩石，以更好地了解基拉韦厄的地幔源非均质性和地壳污染过程。这个项目的结果将使我们能够：评价地幔源非均质性和部分熔融程度变化在控制历史基拉韦厄熔岩地球化学变化中的相对重要性；2. 确定基拉韦厄熔岩中地壳污染的数量，更好地了解其来源的氧同位素非均质性；和3。破译与正在进行的普乌火山喷发有关的地幔融化过程。

EAR-0001123GarciaLavas provide essential clues to the crustal and mantle processes associated with volcanoes. Kilauea Volcano is an ideal natural laboratory for evaluating how physical processes within volcanoes cause observable changes in lava composition and it is the best-studied volcano in the world. Thus, we can address fundamental problems from a well-constrained perspective. This project involves making precise trace element and isotope analyses for quantitative modeling of mantle melting processes, assessing source heterogeneity and evaluating crustal contamination effects on the composition of Kilauea historical lavas. We will make a comprehensive petrologic and geochemical characterization of historical Kilauea lavas, including lavas from the ongoing Puu Oo eruption. We have documented long-term, systematic isotopic and compositional variations within its historical summit lavas (~200 year period) and short-term geochemical variations during the ongoing (17+ years) Puu Oo rift zone eruption. The magma for the Puu Oo and other major rift zone eruptions is thought to have bypassed the summit reservoir and to give us a clearer picture of mantle melting processes and source heterogeneity. The cause for the lower oxygen isotope ratios in oceanic island basalts compared to mid-ocean ridge basalts remains controversial. Some studies have been related the differences to distinct mantle sources, while other studies have invoked crustal contamination. We documented evidence for extensive crustal contamination in some Kilauea historical lavas, including those from the Puu Oo eruption but have not determined the oxygen isotope value for Kilauea's source. New techniques will be use to determine oxygen isotopes for well characterized samples from the ongoing eruption, other historical lavas and hydrothermally altered rocks from a 3 km deep geothermal well to better understand mantle source heterogeneity and crustal contamination processes for Kilauea. The results of this project will allow us to: 1. evaluate the relative importance of mantle source heterogeneity and changes in extent of partial melting in controlling geochemical variation of historical Kilauea lavas; 2. determine the amount of crustal contamination in Kilauea lavas and better understand the oxygen isotope heterogeneity in its source; and 3. decipher the mantle melting processing associated with the ongoing Puu Oo eruption.