Two-Phase Grain Damage and Geochemical Interactions: From Early Tectonic Evolution to Climate and Energy Transitions

地球内部和地表之间的相互作用是通过复杂的过程和广泛变化的时间尺度发生的。在地质时间尺度上，板块构造和地幔翻转支配着地表、大气和海洋的长期演化。相反，在人类的时间尺度上，燃烧化石燃料产生的二氧化碳的快速流出可能最好的缓解方法是通过基性和超基性岩石中的碳封存将其迅速返回地幔。然而，碳封存只是众多缓解气候变化策略中的一种，像天然气这样的低排放燃料也很重要，它跨越了从传统化石燃料到可再生能源长达数十年的过渡。这些复杂的问题通常可以用称为损伤理论的材料物理学领域来处理，即处理构造板块边界的弱化和聚焦以及近地表含流体岩石的微裂缝。这个项目继续发展这样一个理论，叫做两相晶粒损伤理论。该理论简单地指出，进入损伤的能量是变形功，它以表面能的形式存储在微裂纹表面和/或矿物颗粒之间的边界上。特别是，板块生成和早期板块构造和地表演化将使用颗粒损伤理论进行研究，因为变形过程中的颗粒减少（如在被称为糜棱岩的岩石的野外观测中）可能对产生弱板块边界很重要。该项目将试图回答颗粒破坏如何与其他影响相结合，如地幔融化和板块边界的岩石学变化，这对于理解板块构造如何起源于古代太古代地球是很重要的。其次，利用化学反应的两相“微裂缝”损伤，解决地幔源（基性和超基性）岩石的矿物碳固存问题，同时开发页岩气等过渡能源。我们试图回答的问题是，碳酸化反应如何影响损伤（如应力裂纹腐蚀），以及化学反应、晶粒生长和渗透率演化如何影响流体注入过程中的地震活动性。该项目涉及的基础理论有助于解决地质和环境流体力学、岩石力学、材料科学（如冶金学）、气候变化和能源等许多问题。尽管板块构造演化和能量转换的主题涵盖了不同的地质和人类时间尺度，但它们都是可以接近的。此外，地球的长期演变可以告诉我们如何缓解短期失衡。例如，在不把问题推给子孙后代的情况下，减少人为产生的二氧化碳需要一个地质学上的长期解决方案，因此最好通过模拟地球表面的自然演变和循环来解决。

The interaction between Earth's interior and surface occurs through complex processes and over widely varying time scales. On the geological time scale, plate tectonics and mantle overturn govern the long-term evolution of the surface, atmosphere and ocean. Conversely, on the human time scale, the rapid efflux of CO2 from burning fossil fuels is possibly best mitigated by returning it as rapidly to the mantle, through carbon sequestration in mafic and ultramafic rocks. However, carbon-sequestration is only one of many climate-change mitigation strategies, and low-emission fuels like natural gas, which bridge the decades-long transition from traditional fossil fuels to renewable energies, are important as well. These complex issues can be treated commonly with a field of material physics called damage theory, i.e., to treat weakening and focusing of tectonic plate boundaries as well as microcracking in near-surface fluid-bearing rocks. This project continues development of one such theory called two-phase grain-damage theory. This theory simply states the energy going into damage is deformational work that is stored as surface energy on micro-crack surfaces and/or the boundaries between mineral grains. In particular, plate-generation and early plate tectonic and surface evolution will be studied using grain-damage theory, since grain-reduction during deformation (as in field observations of rocks called mylonites) is likely important for generating weak plate boundaries. This project will seek to answer how grain-damage combines with other effects such as mantle melting and petrological changes at plate boundaries, which are important for understanding how plate tectonics originated in the ancient Archean Earth. Secondly, two-phase "micro-crack" damage with chemical reactions will be used to address mineral carbon sequestration in mantle derived (mafic and ultramafic) rocks, along with development of transitional energy such as shale-gas. Questions we seek to answer are how carbonation reaction affects damage (e.g., stress crack-corrosion), and how chemical reactions, grain growth and permeability evolution influence seismicity during fluid injection? The project involves a fundamental theory that contributes to many problems of geological and environmental fluid mechanics, rock mechanics, material science (e.g., metallurgy), climate-change and energy. Although the topics of plate tectonic evolution and energy transitions cover disparate geological and human time-scales, they are approachable with similar scientific advancements. Moreover, the long-term evolution of the Earth can inform us how to mitigate short-term imbalances. For example, reducing anthropogenic CO2, without pushing the problem onto future generations, requires a geologically long-term solution, and is therefore best addressed by mimicking the Earth's natural surface evolution and cycles.