MCA: Advances in Understanding the Biogeochemical Evolution of Serpentinites (AUBES)

该项目由地球科学部的职业中期发展计划（MCA）和促进竞争性研究的既定计划（EPSCoR）共同资助。在地球几十亿年的历史中，微生物的生命精炼了矿物的精细化学，留下了复杂而持久的代谢活动记录。岩石中的裂缝网络保存了这些古老过程的持久矿物记录，经常触及与地球上岩石微生物生命的起源和早期适应策略相关的问题。在这个项目中，从地球地幔中通过科学钻探收集的富铁岩石（也富含铬、镍和其他金属）是地球化学研究的目标，这些岩石是通过加利福尼亚北部海岸山脉蛇绿岩收集的。这些约1.5亿年历史的岩石中的裂缝带是古代地下条件下微生物活动的热点。这项工作使用一系列地球化学工具来绘制裂缝中形成的物质的化学图谱，并应用高能x射线技术（Fe - K edge XANES）来确定裂缝充填矿物中铁的氧化或还原程度，作为过去铁（用于能源）生物地球化学循环的证据。研究包括与布鲁克海文国家实验室的专业光束线科学家以及芒特霍利奥克学院的主题专家D. Dyar博士合作。对这种岩石类型（全球海底下的一个巨大的连续层，也存在于地球表面的大片区域）中矿物反应的进一步了解带来了多种社会效益：使用地球化学模型可以更好地约束这些岩石中不完全了解的自然形成的甲烷（一种温室气体）和氢（一种易燃但迅速损失的气体产物）的排放；铁和相关金属（例如危害健康的Cr6+）释放到穿过这些岩石的渗透水中的情况可以绘制图表并标记，以引起公共卫生注意；这些岩石与二氧化碳的工程反应产生固碳的情况可能会被评估。这项研究的完成还将确保通过多元化和公平思想的研究生和本科教育，多名新一代地球科学家将接受尖端分析工具的培训。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is jointly funded by the Division of Earth Sciences' Mid-Career Advancement (MCA) Program and the Established Program to Stimulate Competitive Research (EPSCoR).Microbial life has refined the fine-scale chemistry of minerals for billions of years of Earth history, leaving complex, durable records of metabolic activity behind. Fracture networks in rocks preserve a durable mineral record of these ancient processes, often touching questions related to the origin and early adaptive strategies of rock-hosted, microbial life on Earth. In this project, iron-rich rocks (also high in chromium, nickel, and other metals) from Earth’s mantle, collected through scientific drilling in northern California’s Coast Range Ophiolite, are targeted for geochemical study. Fracture zones in these ~150-million-year-old rocks were hotspots of microbial activity under ancient conditions in the subsurface. This work uses an array of geochemical tools to map the chemistry of materials formed in fractures and applies a high energy x-ray-based technique (Fe K edge XANES) to define how oxidized or reduced bound iron in fracture fill minerals may be, as evidence for biogeochemical cycling of iron (for energy) in the past. Research involves collaboration with professional beamline scientists at Brookhaven National Lab and with topic expert Dr. D. Dyar of Mount Holyoke College. Increased understanding of the mineral reactions in this rock type (an enormous, continuous layer beneath the global seafloor and also present in extensive blocks at Earth’s surface) brings multiple societal benefits: the incompletely understood emissions of naturally forming methane (a greenhouse gas) and hydrogen (a flammable but quickly lost gaseous product) from these rocks may be better constrained using geochemical models; the release of iron and associated metals (e.g., health-damaging Cr6+) into percolating water passing through these rocks may be charted and flagged for public health attention; and the case for engineered reaction of these kinds of rocks with carbon dioxide to generate sequestered carbon in solids may be evaluated. Completion of this research will also ensure that multiple new generation geoscientists will be trained in cutting edge analytical tools, through diversity- and equity-minded graduate and undergraduate education.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.