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

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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.