From mantle geodynamics to environmental processes: a geochemical perspective

从地幔地球动力学到环境过程：地球化学视角

• 批准号: RGPIN-2018-03764
• 负责人: Weis, Dominique
• 金额: $ 5.46万
• 依托单位: University of British Columbia
• 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=751319
• 关键词: mantle; geodynamics; environmental; processes; geochemical

Modern geochemistry provides us with the ability to investigate fundamental characteristics of our planet by quantifying and explaining the transfer of elements within and between major components of the Earth, including the lithosphere, the hydrosphere, the biosphere, and the atmosphere. Such research requires unprecedented precision and sensitivity for the analysis of elemental concentrations and isotopic ratios in rocks, minerals, water, and organic matter that can only be provided by modern and specific instruments (e.g., mass spectrometers). Importantly, these tools can be applied to many areas of study, including the relationship between our environment and human health. The overall goal of my proposed research program is to constrain the geochemical evolution of our planet and its main reservoirs, to evaluate the impact of pollution on the environment, and to train young scientists in geochemistry to be leaders in the workforce.As the Earth's deep interior cannot be directly sampled, geochemists rely on analyzing lavas to infer the composition of the mantle (84% of Earth's volume). I will study lavas from three large modern mantle plumes (Hawaii, Kerguelen, Galapagos) originating from deep in the mantle. Together with Cascade Arc volcanoes and sediments, I will model the amount of crustal recycling into the mantle using novel isotopic systems allowing to trace different signals and distinguish between recycled sediments, recycled oceanic crust, or slab melting. The results of this research will contribute to the chemical characterization of the mantle and its heterogeneities over geologic time and will transform the current mantle geodynamic model and help build transdisciplinary bridges. My research will also establish the source of Pacific NW volcanoes while identifying some potential hazards related to their activity.I will develop new analytical schemes for mass spectrometers to model oxide formation and problematic matrix effects, which is critical to achieve the best precision and reproducibility. This work will lead to an invaluable set of best practices and methodology for the scientific community. I will also use heavy stable isotope systems coupled with lead fingerprinting to examine element cycling and metal pollution in marine and terrestrial ecosystems as well as to trace the diet and movement of humans and animals through space and time. This work will increase our understanding of ancient climates and the respective roles of humans and nature in the distribution of potential pollutants in British Columbia. Documenting natural levels will help establish clean standards for fisheries and agriculture, and will provide constraints for both modern and ancient human occupation of the landscape.

现代地球化学通过量化和解释地球主要组成部分（包括岩石圈、水圈、生物圈和大气）内部和之间元素的转移，使我们有能力研究地球的基本特征。这种研究需要前所未有的精度和灵敏度来分析岩石、矿物、水和有机物中的元素浓度和同位素比率，而这些只能由现代和特定的仪器（如质谱仪）提供。重要的是，这些工具可以应用于许多研究领域，包括我们的环境与人类健康之间的关系。我提出的研究计划的总体目标是限制我们的星球及其主要水库的地球化学演化，评估污染对环境的影响，并培养地球化学领域的年轻科学家成为劳动力中的领导者。由于地球的深层内部不能直接取样，地球化学家依靠分析熔岩来推断地幔的组成（占地球体积的84%）。我将研究源自地幔深处的三个大型现代地幔柱（夏威夷、凯尔盖伦、加拉帕戈斯群岛）的熔岩。与喀斯喀特弧火山和沉积物一起，我将利用新的同位素系统来模拟地壳再循环到地幔的数量，这种系统可以追踪不同的信号，并区分再循环的沉积物、再循环的海洋地壳或板块融化。本研究的结果将有助于地幔的化学特征及其在地质时期的非均质性，并将改变目前的地幔地球动力学模型，并有助于建立跨学科的桥梁。我的研究还将确定太平洋西北火山的来源，同时确定与它们的活动有关的一些潜在危险。我将为质谱仪开发新的分析方案，以模拟氧化物形成和有问题的基质效应，这对于实现最佳精度和再现性至关重要。这项工作将为科学界带来一套宝贵的最佳实践和方法。我还将使用重稳定同位素系统结合铅指纹技术来研究海洋和陆地生态系统中的元素循环和金属污染，并通过空间和时间追踪人类和动物的饮食和运动。这项工作将增加我们对古代气候的理解，以及人类和自然在不列颠哥伦比亚省潜在污染物分布中的各自作用。记录自然水平将有助于建立渔业和农业的清洁标准，并将为现代和古代人类对景观的占领提供限制。