Water in the Earth's lower mantle

地球上最重要的组成部分是水。它不仅是生命的源泉，而且是控制一系列固体地球过程的关键因素，如板块构造运动、火山的形成和大陆的出现。板块构造和火山喷发导致了地表水和内水的活跃交换，调节了整个地球历史上海洋体积和大陆面积的变化。尽管它很重要，但在今天的地球表面，水只占地球总质量的0.02%。相反，地球上的大部分水被认为存在于地球的内部深处，但地球内部储存的水的确切数量在很大程度上仍然未知。本文将严格研究深地幔中最丰富的物质桥辉石的水溶性。这将通过使用最新的机器学习创新技术，对桥菱石和流体共存的大规模计算机模拟来实现。计算将参考基于量子力学的高精度计算的结果。这项工作将支持使用高性能计算中心培训研究生的尖端计算技术。地幔中的水溶性是一种基本的物质特性，它量化了地球内部可以承载的最大水量。在从头算质量机器学习势的驱动下，对桥菱土和流体共存进行大规模的两相模拟，以严格研究桥菱土中的水溶性。这些模拟将揭示：1)水在桥菱岩中的溶解度以及铁和铝对整个下地幔的影响；2)含氢机制与压力、温度和体化学的关系；3)桥石-水（伪）二元相图；4)近45亿年以来下地幔蓄水能力的演化历史。该项目由地球科学理事会共同资助，旨在支持人工智能/机器学习在地球科学领域的发展。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。

The most vital component of the Earth is water. It is not only the source of life, but also the key ingredient controlling a wide range of solid earth processes, such as the operation of plate tectonics, the formation of volcanoes, and the emergence of continents. Plate tectonics and volcanic eruptions lead to the active exchange of surface water and interior water, regulating the variation of ocean volumes and continent areas throughout the Earth’s history. Despite its importance, in present-day the Earth’s surface water accounts for only 0.02 percent of the planet’s total mass. Most of the Earth’s water is instead thought to be present in the Earth’s deep interior, but the exact amount of water stored in the Earth’s interior remains largely unknown. This proposal will rigorously study the water solubility in bridgmanite, the most abundant material of the deep mantle. This will be accomplished by using large-scale computer simulations of bridgmanite and fluid in coexistence, using the latest innovations in machine learning. The calculations will be referenced to results derived from high-precision calculations based in quantum mechanics. This work will support the training of graduate students in cutting-edge computational techniques using high-performance computing centers. Water solubility in the mantle is a fundamental material property that quantifies the maximum amount of water that can be hosted within the Earth. Large-scale two-phase simulations of bridgmanite and fluid coexistence driven by machine learning potentials of ab initio quality will be carried out to rigorously study the water solubility in bridgmanite. These simulations will reveal: 1) the solubility of water in bridgmanite and the effects of Fe and Al across the entire lower mantle; 2) the hydrogen incorporation mechanisms as a function of pressures, temperatures, and bulk chemistry; 3) the bridgmanite-water (pseudo)-binary phase diagrams; and 4) the evolutionary history of the water storage capacity of the lower mantle over the past 4.5 billion years. This project is co-funded by the Directorate for Geosciences to support AI/ML advancement in the geosciences.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.