Collaborative Research: Characterizing and quantifying carbon sequestration processes across the Andean Convergent Margin

合作研究：描述和量化安第斯汇聚边缘的碳封存过程

• 批准号: 2121670
• 负责人: Karen Lloyd
• 金额: $ 50.08万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2121670&HistoricalAwards=false
• 关键词: Collaborative; Research; Characterizing; quantifying; carbon

Subduction zones are the interface between Earth’s interior (crust and mantle) and exterior (atmosphere and oceans), where carbon and other volatile elements are actively moved between terrestrial reservoirs by plate tectonics. The efficiency of volatile transfer controls the chemical state of Earth’s interior and exterior, including the atmospheric composition. In turn, the distribution of carbon and other volatiles in Earth’s surface reservoirs has enabled conditions favorable for life on Earth. Despite the importance of carbon, its fluxes, sources, and sinks remain under-constrained in subduction-related fluids, with an almost complete absence of studies linking it to underground biological processes. The deep carbon mass balance has previously been estimated by comparing subducting slab inputs to arc volcano degassing outputs, with the difference representing the amount of carbon that is transported into Earth’s deep mantle. However, slab and mantle-derived carbon can also be sequestered in the form of hydrothermal minerals (e.g., calcite, aragonite) and by microbial uptake in the crust of the overriding plate, effectively masking an unknown portion of the carbon output from the subduction zone. The lack of constraints on these key processes, however, limits the understanding of the overall efficiency of the deep carbon cycle. This project involves substantive collaboration with colleagues in Chile, including an international workshop, and the work of several U.S. students will be supported.This project will characterize the extent of mineralogical and biological carbon sequestration along the geologically well-studied Andean Convergent Margin (ACM). The PIs hypothesize that calcite precipitation sequesters significant amounts of carbon in the ACM, particularly where the crust is thickest in the Central Volcanic Zone (CVZ). Furthermore, this project will test if subsurface microbial communities sequester carbon into biomass through chemosynthesis, forming an additional sink for carbon. Finally, the PIs will systematically assess how geochemical transformations and microbial communities vary as a function of subduction parameters (i.e., carbon input from the slab, upper plate thickness and lithology, as well as slab dip angle), which can then be used to compare results to a range of global convergent margins. To accomplish these goals, the PIs will conduct a field expedition to the CVZ in 2022 to collect fluid and gas samples from ~15 natural springs, seeps and fumaroles in the forearc and arc. They will measure helium and carbon isotopes, microbial chemosynthesis rates, and contributions of chemosynthesis to total microbial biomass in all samples. CVZ results will be interpreted alongside published and unpublished datasets from the ACM and other convergent margins globally (i.e., Central America). If subsurface geochemical and biological carbon sinks are found to be substantial in the ACM, it will add to growing evidence that carbon sequestration is widespread in the overlying crust of convergent margins. Such a finding could fundamentally alter the canonical understanding of deep carbon cycling between Earth’s surface and mantle. This project involves substantive collaboration with colleagues in Chile, including an international workshop, and the work of several U.S. students will be supported.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

俯冲带是地球内部（地壳和地幔）与外部（大气和海洋）之间的界面，其中碳和其他挥发性元素通过板块构造在陆地储层之间活跃地移动。挥发性转移的效率控制着地球内部和外部的化学状态。反过来，碳和其他挥发物在地球表面储存库中的分布为地球上的生命提供了有利的条件，尽管碳及其通量、来源和汇很重要。与俯冲相关的流体仍然受到限制，几乎完全没有将其与地下生物过程联系起来的研究。以前通过比较俯冲板片输入和弧火山脱气输出来估计深层碳质量平衡，其差异代表数量。然而，板片和地幔来源的碳也可以以热液矿物（例如方解石、霰石）的形式被封存，并被微生物吸收。然而，对这些关键过程缺乏限制，限制了对深层碳循环整体效率的理解。与智利的同事合作，包括举办国际研讨会，几名美国学生的工作将得到支持。该项目将描述经过地质学充分研究的安第斯辐合边缘沿矿物学和生物碳封存的程度(ACM) 表明方解石沉淀在 ACM 中封存了大量的碳，特别是在中央火山带 (CVZ) 地壳最厚的地方。此外，该项目将测试地下微生物群落是否通过化学合成将碳封存到生物质中。最后，PI 将系统地评估地球化学转变和微生物群落如何随俯冲参数（即来自俯冲带的碳输入）而变化。板片、上部板块厚度和岩性，以及板片倾角），然后可用于将结果与一系列全球会聚边缘进行比较，为了实现这些目标，PI 将在 2022 年对 CVZ 进行实地考察，以了解更多信息。从弧前和弧内的约 15 个天然泉水、渗漏物和喷气孔中收集流体和气体样本，他们将测量氦和碳同位素、微生物化学合成速率和贡献。如果发现 ACM 中存在大量地下地球化学和生物碳汇，则所有样本中微生物生物量的化学合成结果将与 ACM 和全球其他趋同边缘的已发表和未发表的数据集一起进行解释。它将增加越来越多的证据表明碳固存在汇聚边缘的上覆地壳中广泛存在，这一发现可能从根本上改变对地球深层碳循环的规范理解。该项目涉及与智利同事的实质性合作，包括国际研讨会，并将支持几名美国学生的工作。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识进行评估，被认为值得支持。优点和更广泛的影响审查标准。

项目成果

Complex organic matter degradation by secondary consumers in chemolithoautotrophy-based subsurface geothermal ecosystems

基于化能自养的地下地热生态系统中二次消费者对复杂有机物的降解

• 发表时间: 2023-08
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Raegan PaulID 1; Timothy J.
• 通讯作者: Timothy J.