A reactive transport approach for determining cause-and-effect redox relationships in elevated-temperature Earth systems

用于确定高温地球系统中因果氧化还原关系的反应输运方法

• 批准号: RGPIN-2018-03800
• 负责人: Tutolo, Benjamin
• 金额: $ 2.19万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=683333
• 关键词: reactive; transport; approach; determining; cause

Coupled reduction and oxidation (redox) reactions form the chemical underpinnings of many of the processes that we, both as biological organisms and as a society, rely on to live. The objective of this 5-year research program is to develop a comprehensive experiment-, characterization-, and modeling-based reactive transport approach to Fe and C redox processes during serpentinization and silicate diagenesis. These two sets of redox reactions have occurred in the igneous and sedimentary rocks underlying the oceans throughout Earth history. They influence and record global biogeochemical and tectonic cycles, concentrate societally important resources, and fuel various rock-hosted ecosystems. Reactive transport models (RTMs) provide a sophisticated numerical tool for simulating the many coupled processes occurring in these systems, which, in turn, should allow them to predict how a particular system will respond to geologic forcings. In other words, RTMs should allow researchers to distill simplified "cause-and-effect" relationships out of complex Earth systems. However, RTMs currently struggle to model these redox reactions. The innovative approach developed in this research program will build upon recent advancements in analytical capabilities, experimental techniques, and supercomputer-enabled RTMs to explore these individual cause-and-effect relationships. Using this approach, we will explore: 1) the impact of evolving hydraulic properties (i.e., porosity/permeability) on hydrothermal fluxes of reduced gases (hydrogen, H2 and methane, CH4) from serpentinization; 2) the underappreciated role of fluid inclusions in the fluxes of H2 and CH4 from low-temperature serpentinization; 3) the consequences of changes in seawater geochemistry over Earth history on the fluxes of these reduced gases; and 4) the role of organic matter in mineralogical transformations during burial of Fe-bearing sediments. We will particularly work to apply hydrogeologic characterization methods, experiments doped with anomalous isotopes, and international x-ray and neutron beam facilities to characterize reaction processes in both the serpentinization and diagenesis systems. Importantly, this research program will: 1) provide a new, conceptual model describing the roles of individual processes on overall redox reactions during serpentinization; 2) permit enhanced predictions of Fe mineral behavior during hydrocarbon reservoir evolution, CO2 storage in sedimentary rocks, and global Fe and C cycling; and 3) Provide new experimental and characterization methods for quantifying a broad range of geological processes. Together, these results will enhance our collective understanding of Canada's natural environment and the ways in which it can be sustainably exploited for societal benefit.

耦合的还原和氧化（氧化还原）反应形成了我们作为生物有机体和社会赖以生存的许多过程的化学基础。 这项为期5年的研究计划的目标是开发一个全面的实验，表征和建模为基础的反应运输方法，在蛇纹石化和硅酸盐成岩作用的Fe和C氧化还原过程。 这两组氧化还原反应发生在整个地球历史上海洋下面的火成岩和沉积岩中。 它们影响和记录全球地球化学和构造周期，集中了社会重要资源，并为各种岩石生态系统提供燃料。 反应输运模型（RTMs）提供了一个复杂的数值工具，用于模拟这些系统中发生的许多耦合过程，这反过来又应该使他们能够预测一个特定的系统将如何响应地质强迫。 换句话说，RTMs应该允许研究人员从复杂的地球系统中提取简化的“因果”关系。 然而，RTM目前难以模拟这些氧化还原反应。 在这项研究计划中开发的创新方法将建立在分析能力，实验技术和超级计算机支持的RTMs的最新进展的基础上，以探索这些个体的因果关系。 使用这种方法，我们将探讨：1）不断变化的水力特性的影响（即，孔隙度/渗透率）对还原气体热液通量的影响（2）流体包裹体在低温蛇纹岩化作用下H_2和CH_4通量中的作用未被充分认识：（3）地球历史上海水地球化学变化对这些还原气体通量的影响; 4）有机质在含铁沉积物埋藏过程中矿物学转变中的作用。 我们将特别致力于应用水文地质表征方法、掺杂异常同位素的实验以及国际X射线和中子束设施来表征蛇纹石化和成岩系统中的反应过程。 重要的是，这项研究计划将：1）提供一个新的概念模型，描述单个过程在蛇纹石化过程中对整体氧化还原反应的作用; 2）允许在油气藏演化，沉积岩中的CO2储存以及全球Fe和C循环过程中加强对Fe矿物行为的预测; 3）提供新的实验和表征方法，用于量化广泛的地质过程。 总之，这些结果将提高我们对加拿大自然环境的集体理解，以及如何可持续地利用自然环境为社会造福。