Constraints on the Hawaiian Swell and Plume-lithosphere Interaction from Kaua`i Mantle Xenoliths

摘要：0622827 （Bizimis）学术价值：本研究旨在了解热点起源火山洋岛周围浅海底的起源。这项工作对我们理解地幔柱地球动力学、地幔柱如何与岩石圈相互作用以及地幔柱火山作用的起源至关重要。夏威夷海浪是这些区域中研究最广泛的，是研究目标。这项工作利用对考艾岛橄榄岩捕虏体的详细地球化学分析（Hf-Os-Nd-Sr-Pb同位素、微量元素和主要元素浓度）测试了两种不同的地球物理岩石圈变薄模型。化学数据将用于识别来自太平洋岩石圈和地幔柱的橄榄岩特征。如果像在奥胡岛一样，在考艾岛发现了与羽流相关的和原位的太平洋岩石圈成分的橄榄岩，这就证明了大规模的侵蚀和太平洋岩石圈被夏威夷岛下面现在的中心下游的羽流所取代。来自Ka 'ula岛的稀有石榴石辉石岩捕虏体，以及来自O 'ahu盐湖火山口的具有“majorite”前体的石榴石辉石岩，代表了一些来自海洋地幔的最深样本，也将被分析，试图确定不同的辉石岩起源，并确定它们是回收的海洋地壳或高压堆积。由此产生的工作将提供一个新的和前所未有的，四维（空间和时间）的岩石圈上方的羽流视图。更广泛的影响：这项研究直接补充了其他正在进行的美国国家科学基金会资助的项目，其目标是通过对熔岩的研究，对夏威夷膨胀的根源进行成像，并确定夏威夷群岛周围次生火山活动的起源。结果将以出版物和在国家专业会议上发言的形式散发。该研究支持佛罗里达州立大学的一名早期职业科学家，并将涉及与本研究主要研究目标直接相关的本科生地球科学专业的项目。这项研究还将通过美国国家科学基金会资助的国家高磁场实验室（NHMFL）的REU项目参与和培训本科科学专业的学生，并将通过NHMFL正在进行的外展项目，让中学生参与和接触地球科学研究。更多的公众外展活动将在每年的nhmlopen House举行。

ABSTRACT: 0622827 (Bizimis)Intellectual merit: This work seeks to understand the origin of the shallow ocean floor around volcanic ocean islands of proposed hotspot origin. The work is crucial to our understanding of plume geodynamics, how plumes interact with the lithosphere, and the origin of plume volcanism. The Hawaiian swell, the most extensively studied of these regions, is the research target. The work tests two different geophysical lithosphere thinning models using detailed geochemical analyses (Hf-Os-Nd-Sr-Pb isotopes, trace and major element concentrations) of peridotite xenoliths from the island of Kaua`i. Chemical data will be used to identify the signatures of peridotites from the Pacific lithosphere and from the mantle plume. If peridotites with both plume-related and in situ Pacific lithosphere compositions are found at Kaua`i, as they are in O`ahu, this is evidence for large-scale erosion and replacement of the Pacific lithosphere by the plume downstream from its present center under the island of Hawai'i. Rare garnet pyroxenite xenoliths from Ka`ula island, and garnet pyroxenites with "majorite" precursors from Salt Lake Crater, O`ahu, which represent some of the deepest samples from the oceanic mantle will also be analyzed to try and identify different proposed origins of the pyroxenites, and identify them as either recycled oceanic crust or high pressure cumulates. The resulting work will provided a new and unprecedented, 4-dimensional (space and time) view of the lithosphere above a plume.Broader impacts: This research directly complements other ongoing NSF-funded projects, whose objective is to image the root of the Hawaiian swell and determine the origin of the secondary volcanism around the Hawaiian Islands through the study of lavas. Results will be disseminated in the form of publications and presentations at national professional meetings. The research supports an early career scientist in at Florida State University and will involve undergraduate Earth Sciences majors in projects directly related to the main research objectives of this study. This research will also involve and train undergraduate science majors through a NSF-funded REU program at the National High Magnetic Field Lab (NHMFL), and will involve and expose middle school students to research in earth sciences through ongoing outreach programs at the NHMFL. Additional public outreach will occur at the annual NHMFL Open House.