CAREER: Energetics of Mantle Convection and Physics of Earth's Evolution

该项目旨在提高我们对地幔对流能量学及其与地球系统（包括大气、海洋和地核）演化关系的认识。中心主题是势能释放（能量源）和粘性耗散（能量汇）之间的全球平衡，特别是与俯冲带刚性岩石圈强烈变形相关的能量耗散，这可能是板块构造对流最奇特的方面。以下两个问题构成了拟议研究的主干。地幔是如何通过固态蠕变流动的？地幔流变学不仅受温度、压力和应力的控制，还受挥发分含量、相变和晶粒尺寸演化的影响。我们如何通过观察来检验各种理论预测？该项目将通过数值模拟、理论分析和相关地质观测资料的汇编，研究一系列关键的地球动力学问题。整个研究计划由以下七个子主题组成：(1)海洋岩石圈的环境应力状态，(2)板块回滚的能量学，(3)内部加热对流的开始，(4)地幔融化的滞盖对流的标度规律，(5)板块构造的开始，(6)海洋体积和全球水循环的历史，以及(7)核-幔相互作用的性质。总的来说，通过解决尚未解决的一级问题，它们构成了更好地理解地球长期行为的重要一步。此外，它们中的每一个都旨在解决一个独立的基本物理问题，其潜在应用范围超出了本提案的范围，涉及地震地震学，区域构造学，行星科学，前寒武纪地质学，火成岩岩石学，羽流动力学和地磁。本建议包括一名理论地球动力学女博士生的教育。PI还将把研究成果融入他在耶鲁大学定期教授的三门本科/研究生课程中。此外，将开设一门新的200级本科课程，内容是地球演化的物理学，并提供科学计算的实践经验。PI还将通过耶鲁-纽黑文教师研究所开展社区外展活动，通过展示如何在科学课上使用地球物理主题作为友好的例子，帮助K-12教师开发公立学校课程。

This project proposes to improve our understanding of the energetics of convection in Earth's mantle and its relation to the evolution of the Earth system, including the atmosphere, the ocean, and the core. The central theme is the global balance between potential energy release (energy source) and viscous dissipation (energy sink), and in particular, energy dissipation associated with the intense deformation of stiff lithosphere at subduction zones --- probably the most peculiar aspect of plate-tectonic convection. The following two questions form the backbone of the proposed research. How does the mantle actually flow by solid-state creep? Mantle rheology is not only controlled by temperature, pressure, and stress, but also affected by volatile contents, phase transformations, and grain size evolution. And how can we test various theoretical predictions by observations? The PI will study a series of key geodynamical problems through numerical modeling, theoretical analysis, and a compilation of relevant geological observations. The entire research plan is composed of the following seven sub-themes: (1) the ambient state of stress in oceanic lithosphere, (2) the energetics of slab rollback, (3) the onset of convection with internal heating, (4) scaling laws for stagnant-lid convection with mantle melting, (5) the initiation of plate tectonics, (6) the history of ocean volume and global water cycle, and (7) the nature of core-mantle interaction. Collectively, they constitute a major step toward a better understanding of the long-term behavior of Earth, by tackling unresolved first-order issues all together. Moreover, each of them is designed to address a stand-alone, basic physics problem with potential applications beyond the scope of this proposal, reaching out to earthquake seismology, regional tectonics, planetary sciences, Precambrian geology, igneous petrology, plume dynamics, and geomagnetism. This proposal includes the education of one female Ph.D. student in theoretical geodynamics. The PI will also assimilate research results into three existing undergraduate/graduate courses he regularly teaches at Yale. In addition, a new 200-level undergraduate course will be developed on the physics of Earth's evolution, with hands-on experience in scientific computing. The PI will also conduct community outreach through the Yale-New Haven Teachers Institute, to assist K-12 teachers in developing public school curricula, by showing how geophysical topics can be used as friendly examples in science classes.