CSEDI Collaborative Research: Deep Mantle Cycling of Oceanic Crust

这个为期两年的研究项目重点研究在俯冲带潜入地球内部的洋壳和构造板块的命运。 地球的对流地幔将前地壳输送到内部深处，并最终返回地表。 这项工作特别旨在了解地球下地幔中洋壳的化学、结构和动力学。板块构造以及俯冲流将地壳带入地幔深处是一个持续的过程。因此，更好地了解深层迁移地壳的分布、动力学和化学性质，为了解整个地幔的化学和动力学演化提供了一个独特的窗口。过去的工作清楚地确定了地幔如何对流、可行的深部地幔矿物，以及地震检测到的异质性。 这项工作建立在这些想法的基础上，通过研究独特化学系统的已知输入：洋壳，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在海洋和大气的化学和热演化中发挥着作用。该项目采用了多学科方法，因为（a）金刚石砧室中的高压矿物物理学可以研究地幔深处 1000 公里深处的前地壳和沉积物（例如熔体）的特性； (b) 可以通过最先进的数值对流实验来探索前地壳如何与对流流和结构相互作用，包括深层成分储层、热地幔柱和深层地幔化学物质； (c) 前海洋地壳可能与用现代阵列地震学方法观察到的具有未知矿物学的结构有关，包括地幔底部的薄层超低地震波速度区域，以及太平洋和大西洋下方的大片大陆大小的低剪切波速度区域。拟议的多学科工作将包括在 PI 团队中为研究生和博士后研究人员提供强有力的共同指导。

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.