The evolution of the interior of the Earth and solid planets

地球和固体行星内部的演化

• 批准号: RGPIN-2019-06481
• 负责人: Lowman, Julian
• 金额: $ 2.19万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715807
• 关键词: evolution; interior; Earth; solid; planets

My research interest is the thermal evolution of terrestrial planets and specifically planetary mantle and core heat exchange. Convection in planetary mantles is responsible for volcanism, seismicity and orogenesis. It influences a planet's topography and gravitational field, the magnetic field, the formation of mineral deposits and, in Earth's case, drives plate tectonics, continental drift, affects climate and influences cycles of biological evolution. To understand Earth's evolution, it is instructive to study other terrestrial bodies that are composed from the same materials. Rocky bodies throughout the solar system, as well as those detected orbiting more distant stars, provide a long list of puzzling questions: why does the Earth feature plate tectonics while other planets in the solar system do not; could planets elsewhere exhibit plate tectonics; what role does the early history of a planet have in determining whether it will achieve surface mobility; how does interior structure and heterogeneity affect cooling and how do some small moons remain geologically active? To address these issues I'll work with students and experienced collaborators using models that allow for calculations of the evolution of planetary mantle convection. Due to the very different time scales on which motions in planetary cores evolve versus the convective motion in the mantle, modelling mantle convection is not contingent on modelling core convection. Rather, the most common approach is to treat the core as a rapidly mixing reservoir of heat providing a constant temperature at the base of the mantle. Although this approach is well supported for many modelling studies it implies the modelling of a non-evolving planet, if the system is not able to cool. The research plan described here will feature a focus on investigating the influence of heat loss from the core and transitions in regimes as planetary mantles cool. The related projects will utilize tested open source computing tools and provide short term projects for several M.Sc. and senior undergraduate students. A more time-demanding aspect of this line of research will be investigations of the effect of mantle compositional heterogeneity on core cooling. A consensus has formed in the past decade that the lower mantle of the Earth shrouds two large seismically distinct provinces situated atop the core-mantle boundary. The nature of these provinces remains contentious but a possible compositional origin is a leading hypothesis. Such a component in the deep mantle would be an important influence on heat flow from the core due to a thermal blanketing effect. However, the formation, durability and mobility of such features in a cooling planet is not understood. I will work with new PhD students who will investigate the influence of deep mantle heterogeneity on core cooling and the influence of rheology, core size and surface properties on the cooling of the Earth and other terrestrial planetary objects.

我的研究兴趣是类地行星的热演化，特别是行星地幔和地核的热交换。行星地幔中的对流是火山活动、地震活动和造山作用的原因。它影响行星的地形和引力场、磁场、矿藏的形成，就地球而言，它驱动板块构造、大陆漂移、影响气候并影响生物进化周期。为了了解地球的演化，研究由相同材料组成的其他地球体是有启发性的。整个太阳系中的岩石天体，以及那些探测到的绕更遥远恒星运行的岩石天体，提供了一长串令人费解的问题：为什么地球具有板块构造，而太阳系中的其他行星却没有？其他地方的行星是否会表现出板块构造？行星的早期历史在决定其是否实现表面流动方面起什么作用？内部结构和异质性如何影响冷却以及一些小卫星如何保持地质活跃？ 为了解决这些问题，我将与学生和经验丰富的合作者一起使用模型来计算行星地幔对流的演化。由于行星核心运动与地幔对流运动演化的时间尺度非常不同，地幔对流建模并不取决于核心对流建模。相反，最常见的方法是将地核视为快速混合的热库，在地幔底部提供恒定的温度。尽管这种方法得到了许多建模研究的充分支持，但它意味着如果系统无法冷却，则需要对非演化行星进行建模。这里描述的研究计划将重点研究地核热量损失的影响以及行星地幔冷却时状态转变的影响。相关项目将利用经过测试的开源计算工具，并为多个理学硕士提供短期项目。和高年级本科生。 这一系列研究中一个更需要时间的方面是研究地幔成分的异质性对地核冷却的影响。在过去的十年中，人们形成了一种共识，即地球的下地幔覆盖着位于地核-地幔边界顶部的两个地震上不同的大区。这些省份的性质仍然存在争议，但可能的成分起源是一个主要假设。由于热覆盖效应，深部地幔中的此类成分将对来自地核的热流产生重要影响。然而，人们对冷却行星中这些特征的形成、持久性和移动性尚不清楚。我将与新的博士生合作，研究深部地幔异质性对地核冷却的影响，以及流变学、地核尺寸和表面特性对地球和其他类地行星物体冷却的影响。