Chemical heterogeneities in the early Earth and planetary analogues: their formation, preservation and destruction

早期地球和类似行星的化学异质性：它们的形成、保存和破坏

• 批准号: RGPIN-2015-03982
• 负责人: RizoGarza, Hanika
• 金额: $ 3.93万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765318
• 关键词: Chemical; heterogeneities; early; Earth; planetary

A fundamental question in Earth and planetary sciences is how the planets formed and how they evolved through time. Geochemical and numerical models, as well as planetary analogs suggest that Earth accreted from complex processed materials and then evolved rapidly after its formation. Early events such as core segregation, mantle differentiation and crust formation seem to have occurred shortly after the Earth's accretion. Furthermore, the composition of the Earth's mantle was modified by the continued accretion of materials during the final stages of formation. In the past few years, the development of short-lived isotopic chronometers has allowed chronological studies of the events that followed shortly the Earth's accretion. Mixing through mantle convection and crustal recycling associated with plate tectonics has attenuated the magnitude of primordial mantle heterogeneities. However, recent documentation of early-formed isotope variations in Archean rocks requires the persistence of primordial chemical reservoirs for > 1 billion years. Over the next five years my research program will focus on three key problems involving Earth and planetary sciences:1) What are the nature and timing of the major events affecting the chemical composition of the early Earth's mantle?2) How long did early-formed chemical heterogeneities survive in the convective mantle, and what was the style of convection of the early Earth?3) Is the early evolution of the Earth comparable to other planetary analogues like the asteroid Vesta?This research program is strongly focused on the development, improvement and acquisition of data from extinct and long-lived radioactive isotope systematics, as well as obtaining siderophile element abundances for different planetary materials. These geochemical tools are ideal to constrain core and mantle early evolution, and investigate the timing and chemical consequences of late accretionary additions. The findings of this project will help to improve models of the internal dynamics of the Earth during its early stages of development, and provide geological knowledge about the oldest terrains in northern Canada. This research program is designed to involve several undergraduate and four graduate students who will acquire a unique set of skills that are relevant to both academia and industry.

地球和行星科学中的一个基本问题是行星如何形成以及它们如何随着时间的流逝而发展。地球化学和数值模型以及行星类似物表明，地球从复杂的加工材料中积聚，然后在形成后迅速发展。早期事件，例如核心隔离，地幔分化和地壳形成似乎发生在地球积聚后不久。此外，在编队的最后阶段，材料的持续积聚来改变地球地幔的组成。在过去的几年中，短暂的同位素天文组织的发展允许对不久之后地球积聚的事件进行时间顺序研究。通过地幔对流和与板块构造相关的地壳回收混合，已衰减原始地幔异质性的大小。但是，最近关于早期岩石的早期同位素变化的文献需要原始化学储层的持久性超过10亿年。在接下来的五年中，我的研究计划将重点介绍涉及地球和行星科学的三个关键问题：1）主要事件的性质和时机影响着地球早期的地幔化学成分的主要事件？2）2）早期形成的化学异质性在对流的地幔中生存了多长时间？ Vesta？该研究计划重点关注从灭绝和长期寿命的放射性同位素系统的开发，改进和获取数据，并获得不同行星材料的铁载元素丰度。这些地球化学工具是限制核心和地幔早期进化的理想选择，并研究后期增生的时间和化学后果。该项目的发现将有助于在其发展的早期阶段改善地球内部动力学模型，并提供有关加拿大北部最古老的地形的地质知识。该研究计划旨在涉及几位本科生和四个研究生，他们将获得与学术界和行业相关的独特技能。