CSEDI Collaborative Research: Deciphering the LLSVP-plume relationship

我们对地幔演化的大部分看法是由我们目前对地幔对流和地幔柱动力学的了解形成的；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是如何、在哪里、为什么形成的，以及它们的组成和它们与非洲和太平洋深处的大型低横波速度结构（llsvp）的关系，pi将朝着理解地幔的动力学和地球化学演化迈出重要的一步。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地点、方式和原因提供基础。这可能有助于回答这样一个问题：在夏威夷发现的热点熔岩中，羽流和llsvp之间的关系是如何反映的？这些新的研究方向将丰富地幔动力学和地球化学领域之间的相互作用，并为地幔柱和llsvp的研究做出贡献。警务人员参与了一些旨在各级教育和培训的活动。pi已经并将继续让本科生参与他们的研究活动，包括那些来自代表性不足群体的学生。作为这项提议的一部分，pi的目标是增加与维基百科相关条目相关的内容，并开发一系列教育电影，发布在专门的YouTube频道上。这个实验室适合小学生、初中生和高中生实地参观。PI Lithgow-Bertelloni打算继续提供实验室参观，并为中小学生提供参与简单实验的机会。地球内部深处最神秘的方面之一是非洲和太平洋下的异常大低横波速度省（llsvp）。这些省份的起源、组成和动态仍然存在争议。例如，有人提出，羽流主要形成于llsvp的边缘，从llsvp携带的物质解释了在某些热点发现的明显的化学不对称性。pi正在提出一项实验流体动力学研究，以探索三种提出的LLSVP结构如何控制地幔柱并与地幔柱相互作用。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)致密且易变形；C)不可变形的和不耦合的。他们将使用最先进的可视化工具，包括扫描粒子图像测速仪和测温仪来测量三维温度和流场，激光诱导荧光，以及拉格朗日分析工具来定位羽流并量化具有非常高空间和时间分辨率的携射。pi试图测试位置控制和边缘夹带是否解释了热点熔岩中观察到的化学不对称。该奖项反映了美国国家科学基金会的法定使命，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.