Volatile-Bearing Phases at High Pressures and Temperatures: Volatile Release and Retention in Earth's Mantle

对于理解(1)地球的起源和长期体积--S海洋；(2)地球深部岩浆的成因，从而在俯冲相关的环境中发生火山活动，如环太平洋火环；(3)地球深部的粘性行为，从而了解地幔流动和板块构造如何发生，地球内部，特别是地幔内部的深部所保留的水量，是一个关键的重要课题。出于同样的原因，二氧化碳在地球深处的滞留不仅对地球保留了多少碳，而且对有多少二氧化碳在地表和内部之间循环(反之亦然)至关重要。该项目旨在探索在地球高压和高温下-S-地球内部一系列已知的矿物在俯冲带或更深地幔条件下保留水或二氧化碳的性质。它旨在提供数据，以限制水和二氧化碳在深度中保留的数量，例如，通过限制深层水和含碳矿物的可能存在和丰度(通过它们在地震研究中的可能特征)及其地球化学行为(通过探测它们的稳定性和高压相变)。具体地说，将主要针对含挥发物的物相劳钠铝石、黄玉、金云母、白云石和D相，因为这些物相代表着从近地表俯冲到地球内部的物质中的主要含挥发物相。将同时使用X射线衍射和光谱探头，重点将放在同时进行高压和高温实验--这些实验将利用现有的和最近增强的高压、高温能力。这些研究建立并扩展了由PI及其合作者进行的一系列关于300K压缩时含氢和含碳相的表征。这些结果将对高压和高温下矿物中水和碳的成键性质以及这些材料的热力学性质(特别是状态方程)提供新的限制。

The amount of water retained at depth within the Earth, and particularly within Earth's mantle, is a topic of key importance for understanding (1) the genesis and long-term volume of Earth?s oceans; (2) the genesis of magmas within the deep interior of the Earth, and thus the occurrence of volcanism in subduction-related environments, such as the circum-Pacific ring-of-fire; and (3) the viscous behavior of the deep planet, and hence for how the mantle flows and plate tectonics occurs. By the same token, the retention of carbon dioxide within the deep Earth is of critical importance for not only how much carbon the planet retains, but also for how much carbon dioxide has been cycled between the surface and the interior (and vice-versa). This project is designed to probe the properties at the high pressures and temperatures of Earth?s interior of a range of minerals known to retain water or carbon dioxide at either subduction zone or deeper mantle conditions. It is oriented towards providing data that will constrain how much water and carbon dioxide is retained at depth through, for example, constraining the likely presence and abundance of water and carbon-containing minerals at depth (through their likely signature in seismic studies) and their geochemical behavior (through probing their stability and high-pressure phase transitions).Specifically, the volatile-bearing phases lawsonite, topaz, phlogopite, dolomite and phase D will be primarily targeted, as these represent major volatile-bearing phases within material that is subducted from the near-surface into the planet's interior. Both x-ray diffraction and spectroscopic probes will be utilized, and the focus will be on simultaneous high-pressure and high-temperature experiments-these will take advantage of both extant and recently augmented high-pressure, high-temperature capabilities. These studies build and expand on a broad suite of characterizations of hydrogen- and carbon-bearing phases on compression at 300 K conducted by the PI and collaborators. The results will provide new constraints on the bonding properties of water and carbon within minerals at high pressures and temperatures, as well as on the thermodynamic properties (and particularly the equations of state) of these materials.