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

地球内部和表面之间的相互作用通过复杂的过程和广泛不同的时间尺度发生。在地质时间尺度上，板块构造和地幔倾覆控制着地表、大气和海洋的长期演化。相反，在人类的时间尺度上，通过镁铁质和超镁铁质岩石中的碳封存，将二氧化碳迅速返回地幔，可能是缓解燃烧化石燃料产生的二氧化碳的最好方法。然而，碳封存只是许多气候变化缓解策略之一，天然气等低排放燃料也很重要，天然气是数十年来从传统化石燃料向可再生能源过渡的桥梁。这些复杂的问题通常可以用一种被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削弱和聚焦以及近地表含流体岩石中的微裂缝。该项目是对两相颗粒损伤理论的继续发展。这一理论简单地说，进入损伤的能量是变形功，作为表面能储存在微裂纹表面和/或矿物颗粒之间的边界上。特别是，将使用颗粒损伤理论研究板块生成和早期板块构造和表面演化，因为变形过程中的颗粒减少(如在称为糜棱岩的岩石的野外观测中)可能对产生薄弱的板块边界很重要。这个项目将寻求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，这些对于理解板块构造如何起源于古代太古宙地球非常重要。其次，随着页岩气等过渡性能源的发展，两相化学反应微裂缝损伤将被用来解决地幔(镁铁质和超镁铁质)岩石中矿物碳的固存问题。我们试图回答的问题是碳化反应如何影响损害(例如，应力裂缝-腐蚀)，以及化学反应、颗粒生长和渗透率演变如何影响流体注入过程中的地震活动？该项目涉及一个基础理论，它对地质和环境流体力学、岩石力学、材料科学(例如冶金学)、气候变化和能源等许多问题做出了贡献。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，但它们可以通过类似的科学进步来接近。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，减少人为的二氧化碳，而不把问题推给子孙后代，需要一个地质上的长期解决方案，因此最好通过模仿地球自然表面的演变和周期来解决。

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.