The Mantle Melt Column and Melt Migration Revealed by Deglaciation Melting Beneath Iceland's Western Rift Zone

冰岛西部裂谷带下方冰消融化揭示的地幔熔柱和熔体迁移

• 批准号: 0911301
• 负责人: John Sinton
• 金额: $ 29.57万
• 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: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911301&HistoricalAwards=false
• 关键词: Mantle; Melt; Column; Migration; Revealed

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Magma that feeds volcanic eruptions on oceanic islands and most of the deep ocean is produced by melting of the underlying mantle. Current knowledge of the details of magma genesis and transport are derived from observations of eruption rates and basalt chemistry coupled to numerical modeling. However, because the products of volcanic activity usually provide only a time-integrated view of the melt migration process, it is normally very difficult to constrain the important rates and time scales of melt transport. This project will exploit the unique situation of time-varying melting perturbations due to glacial unloading in Iceland to provide unprecedented constraints on aspects of mantle melting that will be applicable to mantle melting studies in a wide range of geological settings. The project has a significant international component involving collaboration with the University of Iceland. It also has a major educational and training component for a young scientist who will have recently obtained her PhD at the University of Hawai'i. With this project she will gain experience in field mapping and Icelandic geology and volcanology as well as learn new techniques in a range of geochemical analyses and in sophisticated geodynamic modeling. The project is intended to involve undergraduate students from the University of Hawaii in the field work and follow-on research. The proposed research will enrich teaching and research programs at the University of Hawaii, which is located in an ethnically diverse community, including people from a range of Asian and Pacific island countries. It will therefore provide advanced technological training and mentoring of science students with diverse cultural backgrounds. Theory and preliminary observations indicate that the removal of ice at the end of the last glacial period profoundly affected volcanic production and magma chemistry in Iceland. The project investigators will constrain the timing of glacial retreat using ice core data and geologic reconstructions for the period between 15 and 11 thousand years before present. They will use new geologic mapping and sample collections, geochemical analyses, and 3He exposure age dating of subaerial lavas that surmount late-glacial table mountains to extend the record of eruption rates and lava composition back to 15 ka. Numerical models will simulate the updated glacial unloading history as well as the resulting perturbations to mantle melting, melt migration, and chemical transport. By modeling the observed temporal variations in eruption rate and trace-element and isotopic compositions, they will constrain the rates of melt transport, determine basic properties of the mantle melt column, and test for the presence of small-scale mantle heterogeneity.

该奖项是根据2009年《美国复苏与再投资法》（公法111-5）资助的。 岩浆在海洋岛和大部分深海中供应火山喷发的岩浆是通过底层地幔融化而产生的。 当前对岩浆起源和运输细节的知识来自于对喷发速率和玄武岩化学与数值建模结合的观察结果。 但是，由于火山活动的产物通常仅提供融化迁移过程的时间融合视图，因此通常很难限制熔体运输的重要速率和时间尺度。 由于冰岛的冰川卸载，该项目将利用随时间变化的融化扰动的独特状况，以在地幔融化方面提供前所未有的约束，这些限制适用于在广泛地质环境中的地幔融化研究。 该项目具有与冰岛大学合作的重要国际组成部分。 它还为年轻科学家提供了一个主要的教育和培训组成部分，他们最近将在夏威夷大学获得博士学位。 通过这个项目，她将获得现场映射和冰岛地质和火山学的经验，并在一系列地球化学分析和复杂的地球动力学建模中学习新技术。 该项目旨在让夏威夷大学的本科生参与现场工作和后续研究。 拟议的研究将丰富夏威夷大学的教学和研究计划，该大学位于一个种族多元化的社区，包括来自亚洲和太平洋岛屿国家的人们。 因此，它将提供具有多种文化背景的科学专业学生的高级技术培训和指导。理论和初步观察表明，在最后一个冰川时期的结束时去除冰，对冰岛的火山产量和岩浆化学产生了深远影响。 项目研究人员将使用ICE核心数据和地质重建在目前的15至11千年之间来限制冰川撤退的时间。 他们将使用新的地质图和样品收集，地球化学分析以及3HE曝光熔岩的暴露年龄，以覆盖后期冰川桌山，以将喷发率和熔岩组成的记录扩展到15 ka。 数值模型将模拟更新的冰川卸载历史记录，以及对地幔熔化，融化迁移和化学运输的扰动。 通过对观察到的喷发速率和痕量元素和同位素组合物的时间变化进行建模，它们将限制熔体转运的速率，确定地幔熔体柱的基本特性，并测试是否存在小规模地幔异质性。