CSEDI Collaborative Research: Deciphering the LLSVP-plume relationship

我们对地幔演化的大部分看法都是由我们目前对地幔对流和地幔柱动力学的认识形成的;例子包括热点火山活动-包括大型火成岩省-和地幔混合。通过更深入地了解地幔柱的形成方式、位置和原因，以及它们的组成和它们与非洲和太平洋深部内部大型低剪切波速度结构的关系，PI将朝着了解地幔的动力学和地球化学演化迈出重要一步。他们的努力应该为更好地理解LLSVP周围的三维流动结构以及羽流形成的位置、方式和原因提供基础。这可能有助于回答这个问题：羽流和LLSVP之间的关系如何反映在热点熔岩中，例如在夏威夷发现的熔岩？新的研究方向将丰富地幔动力学和地球化学领域之间的交叉施肥，并有助于地幔柱和LLSVP的工作越来越多。公共机构参与了一系列旨在各级教育和培训的活动。PI已经并将继续吸引本科生，包括来自代表性不足群体的学生参与其研究活动。作为该提案的一部分，PI旨在增加与相关维基百科条目相关的内容，并开发一系列教育电影，以发布在专门的YouTube频道上。该实验室适合小学、初中和高中学生现场参观。PI Lithgow-Bertelloni打算继续提供实验室图尔斯之旅，并为小学和中学的孩子们提供参与简单实验的机会。地球深部最神秘的方面之一是非洲和太平洋下面的异常大的低剪切波速度区（LLSVP）。这些省份的起源、组成和动态仍然存在争议。例如，有人认为，羽流主要形成在LLSVP的边缘，LLSVP夹带的物质解释了在某些热点发现的独特化学不对称性。PI正在提出一项实验流体动力学研究，以探索三种拟议的LLSVP结构如何控制地幔柱并与之相互作用。这三种结构代表了迄今为止提出的LLSVP形成假设的范围：a）纯热; B）致密和可变形; c）不可变形和不耦合。他们将使用最先进的可视化工具，包括扫描粒子图像测速和测温来测量三维温度和流场，激光诱导荧光和拉格朗日分析工具来定位羽流并将夹带量化到非常高的空间和时间分辨率。PI旨在测试位置控制以及边缘夹带是否解释了热点熔岩中观察到的化学不对称性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Much of our view of mantle evolution is shaped by our current knowledge of mantle convection and plume dynamics; examples include hotspot volcanism--including large igneous provinces--and mantle mixing. By gaining a deeper understanding of how, where, and why plumes form, and their composition and their relationship to the deep interior's large low shear wave velocity structures (LLSVPs) under Africa and the Pacific, the PIs will make a significant step towards understanding the dynamical and geochemical evolution of the mantle. Their efforts should provide a basis to better understand the three-dimensional flow structure surrounding LLSVPs and where, how, and why plumes form. This may help answer the question: How is the relationship between plumes and LLSVPs reflected in hotspot lavas such as those found in Hawaii? The new research directions will enrich cross-fertilization between the fields of mantle dynamics and geochemistry and contribute to the growing body of work on mantle plumes and LLSVPs. The PIs are engaged in a number of activities aimed at education and training at all levels. The PIs have and will continue to engage undergraduate students, including those from underrepresented groups in their research activities. As part of this proposal the PIs aim to augment the content associated with related Wikipedia entries and develop a series of educational films to post on specifically dedicated YouTube channels. The lab lends itself to site visits by elementary, middle school and high school students. PI Lithgow-Bertelloni intends to continue providing lab tours and opportunities for elementary and middle-school children to be involved in simple experiments.Amongst the most enigmatic aspects of the Earth's deep interior are the anomalous large low shear wave velocity provinces (LLSVPs) under Africa and the Pacific. The origin, composition, and dynamics of these provinces remain controversial. For example, it has been suggested that plumes predominantly form at the edges of LLSVPs and that entrained material from LLSVPs explains the distinct chemical asymmetries found at certain hotspots. The PIs are proposing an experimental fluid dynamical study to explore how three proposed LLSVP structures control and interact with mantle plumes. These three structures represent the range of LLSVP formation hypotheses so far proposed: a) purely thermal; b) dense and deformable; c) undeformable and uncoupled. They will use state-of-the-art visualization tools, including scanning particle image velocimetry and thermometry to measure the three-dimensional temperature and flow fields, laser induced fluorescence, and Lagrangian analysis tools to locate plumes and quantify entrainment to very high spatial and temporal resolutions. The PIs seek to test both location control and whether entrainment at the edges explains the observed chemical asymmetry in hotspot lavas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.