A giant and persistent source of abiotic H2 and CH4 driven by slab rehydration

A giant and persistent source of abiotic H2 and CH4 driven by slab rehydration | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article A giant and persistent source of abiotic H2 and CH4 driven by slab rehydration Lifei Zhang, Zengli Guo, Renbiao Tao, Ning Qi, Chao Wang, Guibin Zhang, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9346996/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The origin and flux of geologically sourced abiotic hydrogen (H2) and methane (CH4) in Earth’s crusts are fundamental to understanding deep carbon and hydrogen cycles, the formation of deep energy resources, and the potential to sustain subsurface biospheres. While forearc serpentinization has long been considered the dominant abiotic hydrocarbon source in subduction zones, our study reveals a distinct and previously overlooked pathway: intraslab fluid–reactive transport at much greater depths. We investigated abundant CH4–H2-bearing fluid inclusions in carbonated eclogites from the Southwestern Tianshan paleo-subduction zone. Thermodynamic and numerical modeling indicate that oxidized altered oceanic crust may be insufficiently reduced to generate CH4–H2-rich fluids. Alternatively, enhanced hydration of subducting fresh oceanic crust can markedly lower oxygen fugacity, generating abundant abiotic CH4 and even H2 in metamorphic fluids. Prograde deserpentinization fluids thus migrate upward and react with relatively unaltered oceanic crust, providing a significant and persistent source of CH4–H2-bearing fluids, particularly in cold subduction zones. Given the substantial fluid fluxes from deserpentinization and associated carbon mobilization, we estimate that intraslab fluid transport has the potential to generate CH4–H2 fluxes comparable in magnitude to those originated by ridge-spreading hydrothermal alteration and deep serpentinization. This process may significantly modify the redox gradient in subduction zones, thereby contributing to the accumulation of abiotic crustal energy sources and influencing shallow biosphere ecosystems. Earth and environmental sciences/Solid Earth sciences/Petrology Earth and environmental sciences/Solid Earth sciences/Geology/Economic geology Full Text Additional Declarations There is NO Competing Interest. Supplementary Files 2SupplementaryInformation.pdf A giant and persistent source of abiotic H2 and CH4 driven by slab rehydration Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9346996","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":619479354,"identity":"f87a7f46-b93b-44af-9331-107671522d01","order_by":0,"name":"Lifei 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