Water in the Earth's lower mantle

地球上最重要的成分是水。它不仅是生命的源泉，也是控制广泛的固体地球过程的关键因素，如板块构造的运行、火山的形成和大陆的出现。板块构造和火山喷发导致地表水和内陆水的活跃交换，调节了地球历史上海洋体积和大陆地区的变化。尽管它很重要，但在今天，地球表面的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深处，但地球内部储存的确切水量在很大程度上仍是未知的。这项提议将严格研究深部地幔中最丰富的物质--镁橄榄石中的水的溶解度。这将通过利用机器学习中的最新创新，对桥锰矿和流体共存的大规模计算机模拟来实现。这些计算将参考基于量子力学的高精度计算得出的结果。这项工作将支持使用高性能计算中心对研究生进行尖端计算技术培训。地幔中的水的溶解度是一种基本的物质性质，它量化了地球内可以容纳的最大水量。在从头算性质的机器学习潜能的驱动下，将进行大规模的两相模拟，以严格研究水在水中的溶解度。这些模拟将揭示：1)水在水中的溶解度以及Fe和Al对整个下地幔的影响；2)氢的结合机制作为压力、温度和主体化学的函数；3)水-水(伪)-二元相图；以及4)过去45亿年来下地幔储水量的演化史。该项目由地球科学局共同资助，以支持AI/ML在地球科学领域的进步。该奖项反映了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。

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.