CSEDI Collaborative Research: Deciphering the LLSVP-plume relationship

我们对地幔演化的大部分观点是由我们目前对地幔对流和羽流动力学的知识形成的；例如热点火山作用--包括大型火成岩省--和地幔混合。通过更深入地了解羽流是如何、在哪里和为什么形成的，它们的组成及其与非洲和太平洋下深部巨大的低剪切波速度结构(LLSVP)的关系，PI将在理解地幔的动力学和地球化学演化方面迈出重要的一步。他们的工作应该为更好地理解低空对流热泵周围的三维流动结构以及羽流在哪里、如何形成和为什么形成提供了基础。这可能有助于回答这个问题：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？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，并有助于不断增长的地幔热柱和LLSVP方面的工作。警察参与了一系列旨在各级教育和培训的活动。私人投资促进机构已经并将继续邀请本科生，包括那些来自代表人数不足的群体的学生参与他们的研究活动。作为这项提议的一部分，私人投资者的目标是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，以便在专门的YouTube频道上发布。该实验室适合小学生、初中生和高中生的现场参观。PiLithgow-Berelloni计划继续为中小学生提供实验室之旅和参与简单实验的机会。地球深处最神秘的方面是非洲和太平洋下异常大的低剪切波速度省(LLSVP)。这些省份的起源、组成和动态仍然存在争议。例如，有人认为羽流主要形成在LLSVP的边缘，来自LLSVP的夹带物质解释了在某些热点发现的明显化学不对称。PIS正在提议进行一项实验性的流体动力学研究，以探索三个拟议的LLSVP结构如何控制地幔热柱并与之相互作用。这三种结构代表了迄今为止提出的LLSVP形成假说的范围：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，以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，以定位羽流和量化卷吸到非常高的空间和时间分辨率。PIS试图测试位置控制和边缘的夹带是否解释了观察到的热点熔岩中的化学不对称。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势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.