Collaborative Research: Hawaiian Plume Heterogeneity Revealed by Kilauea's Ongoing Eruption, Prehistoric Lavas and Olivine-hosted Melt Inclusions

合作研究：基拉韦厄火山的持续喷发、史前熔岩和橄榄石熔融包裹体揭示了夏威夷羽流的异质性

• 批准号: 0738671
• 负责人: Aaron Pietruszka
• 金额: $ 13万
• 依托单位: San Diego State University Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0738671&HistoricalAwards=false
• 关键词: Collaborative; Research; Hawaiian; Plume; Heterogeneity

Intellectual Merit. Kilauea, on the island of Hawaii, is one of the most active and best-monitored volcanoes in the world. Its high magma supply rate and well delineated magmatic plumbing system make Kilauea an ideal venue for addressing fundamental questions about basaltic magma genesis. Its lavas provide essential petrologic and geochemical clues for delineating the nature of compositional heterogeneity within the Hawaiian plume and for assessing magma generation processes that cannot be readily ascertained by other methods. The PIs previously documented systematic short- and moderate-term (decades to centuries) geochemical variations within Kilauea's recent lavas. Over several centuries, Kilauea summit lavas record cyclic geochemical trends that correlate with volcanic processes such as eruption rates (more depleted sources appear to have undergone lower degrees of melting and produced less magma). To continue this work, a three-pronged approach is proposed combining field work with petrography, mineral chemistry, whole-rock major element and trace element abundances, and O, Pb, Sr, and Nd isotope ratios to assess the mantle causes (source and process) for compositional variation in Kilauea lavas. Part 1 involves continued monitoring of the geochemical evolution of the Puu Oo eruption, which has shown remarkable compositional variation related to crustal and mantle processes. Changing lava compositions provide new insights into magmatic processes. Part 2 examines the AD 900 to 1400 Uwekahuna Bluff lava section on the northwestern wall of the Kilauea's caldera. This study will allow evaluation of apparently cyclic geochemical variations at Kilauea on a few century time scale, and elucidate distribution of small-scale heterogeneities and the dynamics of mantle melting within the Hawaiian plume. Part 3 utilizes electron microprobe, LA-ICPMS, O isotope laser mass spectrometry and SHRIMP ionprobe to study olivine-hosted melt inclusions in high forsterite olivines (86%) from selected Kilauea historical summit lavas. Preliminary work on these inclusions shows tremendous compositional diversity within individual lavas that may be related to the relatively short residence of magma in the summit reservoir (30-100 years). Major- and trace-element abundances, and O and Pb isotope ratios will be determined in these inclusions to better constrain the mantle heterogeneities and melting processes within the Hawaiian plume.Broader Impacts. Broader impacts of this research include (1) developing teaching modules for undergraduate and graduate petrology classes using the results from our Kilauea research to highlighting magmatic processes at an active volcano and emphasing cooperative learning and development of higher order thinking skills, (2) mentoring graduate and undergraduate students, (3) giving public lectures to school groups and the local community, (4) gaining a better understanding of volcanoes that can negatively influence the quality of life, and (5) increasing international and national scientific cooperation through collaboration and utilization of multiuser facilities.

智力优点。夏威夷大岛的基拉韦厄火山是世界上最活跃、监控最完善的火山之一。其高岩浆供应率和轮廓清晰的岩浆管道系统使基拉韦厄成为解决玄武岩岩浆成因基本问题的理想场所。它的熔岩提供了重要的岩石学和地球化学线索，用于描述夏威夷羽流内成分异质性的性质，并评估其他方法无法轻易确定的岩浆生成过程。 PI 之前记录了基拉韦厄近期熔岩内系统性的短期和中期（几十年到几个世纪）地球化学变化。几个世纪以来，基拉韦厄山顶熔岩记录了与火山过程相关的周期性地球化学趋势，例如喷发率（更枯竭的来源似乎经历了较低程度的熔化并产生了较少的岩浆）。为了继续这项工作，提出了一种三管齐下的方法，将现场工作与岩相学、矿物化学、全岩主量元素和微量元素丰度以及 O、Pb、Sr 和 Nd 同位素比率相结合，以评估地幔成因（源和过程）以了解基拉韦厄熔岩的成分变化。第 1 部分涉及持续监测 Puu Oo 喷发的地球化学演化，该喷发显示出与地壳和地幔过程相关的显着成分变化。熔岩成分的变化为岩浆过程提供了新的见解。第 2 部分考察了基拉韦厄火山口西北壁上公元 900 年至 1400 年的乌韦卡胡纳悬崖 (Uwekahuna Bluff) 熔岩部分。这项研究将能够在几个世纪的时间尺度上评估基拉韦厄明显的周期性地球化学变化，并阐明小尺度异质性的分布和夏威夷地幔柱内地幔熔化的动态。第 3 部分利用电子显微探针、LA-ICPMS、O 同位素激光质谱和 SHRIMP 离子探针来研究来自选定的基拉韦厄历史峰熔岩的高镁橄榄石橄榄石 (86%) 中的橄榄石熔融包裹体。对这些包裹体的初步研究表明，各个熔岩内存在巨大的成分多样性，这可能与岩浆在山顶储层中的停留时间相对较短（30-100 年）有关。将确定这些包裹体中的主量元素和微量元素丰度以及 O 和 Pb 同位素比率，以更好地限制夏威夷地幔柱内的地幔异质性和熔化过程。更广泛的影响。这项研究的更广泛影响包括（1）利用我们基拉韦厄研究的结果为本科生和研究生岩石学课程开发教学模块，以突出活火山的岩浆过程并强调合作学习和高阶思维技能的发展，（2）指导研究生和本科生，(3) 向学校团体和当地社区进行公开讲座，(4) 更好地了解可能对生活质量产生负面影响的火山，以及 (5) 通过协作和利用加强国际和国家科学合作的多用户设施。