Accomplishment Based Renewal: Magmatic Processes at Mid-Ocean Ridges

摘要（0524922）Sinton Intellectual Merit：本项目研究控制大洋中脊火山岩化学成分和矿物学的过程。它特别讨论了上升流地幔的熔融变化如何影响原始岩浆的组成，以及这些岩浆如何通过在地壳和地幔不同深度的冷却和结晶而在化学和矿物学上发生变化。本研究结合了理论模型、地壳厚度的地球物理约束、加拉帕戈斯扩张中心和冰岛西部火山带洋中脊自然样品的化学和岩石学分析。这些对比样本集将有助于评估扩张速率、地幔源成分、地幔温度、地壳厚度和喷发方式的变化如何在扩张脊的特定位置造成海洋中脊熔岩的物理和化学变化。这项工作包括确定选定样品中个别矿物（橄榄石、长石、辉石和氧化物）的相对比例，并分析这些矿物以及整个岩石样品的化学成分。具体样品组包括：(1)来自加拉帕戈斯群岛地区的不寻常的海底熔岩，铝含量非常高；(2)来自加拉帕戈斯群岛地区的至少两个其他样本集，代表了与构成加拉帕戈斯群岛的地幔异常距离不同的样本；(3)两个喷发单元的年龄和位置与冰岛暴露的海中脊相近。冰岛的工作将调查单次喷发期间不同时间喷发的样本，这将使我们能够以加拉帕戈斯群岛地区不可能的方式解决喷发过程。它还允许在短的空间（~20公里）和时间（~400年）尺度上研究地幔来源、熔融条件和岩浆演化过程的变化。更广泛的影响：这项工作支持了夏威夷大学的一名教员和研究生。学生培训将包括广泛的分析和岩石学技术和理论，以及冰岛地质学的介绍。本科学生将参与准备岩石样品进行化学和岩石学分析。这项研究的结果将纳入课堂教学和社区报告，并发表在广泛查阅的同行评议期刊文章中。

ABSTRACT (0524922) Sinton Intellectual Merit: This project investigates processes that control the chemical composition and mineralogy of mid-ocean ridge volcanic rocks. It specifically addresses how variations in melting of upwelling mantle affect the composition of primary magmas and how these magmas are changed in chemistry and mineralogy by cooling and crystallization at different depths in the crust and mantle. This research combines theoretical models, geophysical constraints on the thickness of the crust, and chemical and petrographic analyses of natural samples from the Galapagos Spreading Center and Icelandic Western Volcanic Zone mid-ocean ridges. These contrasting sample sets will allow evaluation how variations in spreading rate, mantle source composition, mantle temperature, crustal thickness and variations in eruptive style create physical and chemical variations in mid-ocean ridge lavas at specific locations along spreading ridges. The work involves determining the relative proportions of individual minerals (olivine, feldspar, pyroxene and oxide) in selected samples and analyzing for the chemical compositions of these minerals as well as of whole-rock samples. Specific sample sets include: (1) unusual submarine lavas from the Galapagos area with very high aluminum contents; (2) at least two other sample sets from the Galapagos area that represent samples with varying distance from the mantle anomaly that is responsible for the Galapagos archipelago; and (3) Two eruptive units close in age and location from the subaerial mid-ocean ridge exposed in Iceland. The Icelandic work will investigate samples erupted at different times during single eruption episodes, which will allow us to address eruptive processes in ways not possible in the Galapagos area. It also permits investigation of variations in mantle sources, melting conditions and magma evolution processes over short spatial (~20 km) and temporal (~400 years) scales.Broader Impacts: This work supports a faculty member and graduate student at the University of Hawaii. Student training will include a wide range of analytical and petrological techniques and theory, as well as an introduction to Icelandic geology. Undergraduate students will be involved in the preparation of rock samples for chemical and petrographic analysis. Results of this research will be incorporated into classroom teaching and community presentations and published in widely accessible peer-reviewed journal articles.