CSEDI Collaborative Research: Deep Mantle Cycling of Oceanic Crust

这项为期两年的研究项目专注于调查在俯冲带潜入地球内部的洋壳和构造板块的命运。地球的对流地幔将以前的地壳输送到内陆深处，并最终返回地表。这项工作专门致力于了解地球下地幔中洋壳的化学、结构和动力学。板块构造和俯冲洋流将地壳带入深部地幔是一个持续的过程；因此，更好地了解深部搬运地壳的分布、动力学和化学特征，为了解整个地幔的化学和动力学演化提供了独特的窗口。过去的工作清楚地确定了地幔可能如何对流，可行的深部地幔矿物，以及存在地震探测到的不均质性。这项工作建立在这些概念的基础上，通过研究独特化学系统的一个已知输入：洋壳，试图将它们联系起来。这项工作具有广泛的影响，因为地幔的演化最终对海洋和大气的化学和热演化起到了作用。这个项目采用了多学科的方法，因为：(A)钻石砧腔中的高压矿物物理可以研究在地幔深处1000‘S条件下的前壳和沉积物(例如，熔体)的性质；(B)可以用最先进的数值对流实验来探索前壳如何与对流流动和结构相互作用，包括深部成分储集层、热地幔羽流和深部地幔化学；(C)前洋壳可能与用现代阵列地震学方法观测到的矿物学未知的构造有关，包括地幔底部的薄层极低地震波速带，以及太平洋和大西洋之下大陆大小的低剪切波速带。拟议的多学科工作将包括在研究生和博士后研究人员的PI团队中采取强有力的共同指导方法。

This 2-year research project focuses on investigating the fate of oceanic crust and tectonic plates that dive into Earth's interior at subduction zones. Earth's convecting mantle transports the former crust to the deep interior, and eventually back up to the surface. This work specifically seeks to understand the chemistry, structure, and dynamics of oceanic crust in Earth's lower mantle. Plate tectonics and thus subduction-currents carrying crust into the deep mantle are an ongoing process; thus better understanding the distribution of, the dynamics of, and chemistry of deeply transported crust uniquely provides a window into the chemical and dynamical evolution of Earth's mantle as a whole. Past work clearly establishes how the mantle might convect, viable deep mantle minerals, and that there are seismically detected heterogeneities. This work builds upon these ideas by seeking to connect them via studying a known input into the system of unique chemistry: the oceanic crust. This work has broad impact, since the mantle's evolution ultimately plays a role in the chemical and thermal evolution of the oceans and atmosphere. A multidisciplinary approach is adopted for this project, since (a) high pressure mineral physics in the diamond anvil cell can investigate the properties of former crust and sediments (e.g., melt) at conditions 1000's of km deep in Earth's mantle; (b) how former crust interacts with convective flow and structures, including deep compositional reservoirs, hot mantle plumes, and deep mantle chemistries can be explored with state-of-the-art numerical convection experiments; and (c) former oceanic crust may relate to structures observed with modern array seismology methods that have unknown mineralogy, including thin ultra low seismic wave speed zones at the bottom of the mantle, as well as massive continent-sized zones of low shear wave velocities beneath the Pacific and Atlantic Oceans. The multidisciplinary proposed work will include a strong co-mentoring approach among the team of PIs for the graduate student and postdoctoral researchers.