Mid-mantle discontinuities beneath subduction zones linked to depth-dependent deformation of bridgmanite

Mid-mantle discontinuities beneath subduction zones linked to depth-dependent deformation of bridgmanite | 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 Mid-mantle discontinuities beneath subduction zones linked to depth-dependent deformation of bridgmanite John Keith Magali, Sébastien Merkel, Angelo Pisconti, Jeffrey Gay, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7039328/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 Bridgmanite, the main mineralogical phase in the Earth’s lower mantle, is intrinsically anisotropic and may therefore generate seismic anisotropy in actively-deforming regions, particularly subduction zones. Bulk of the lower mantle is widely regarded as well-mixed but recent seismic observations suggest structures at mid-mantle depths whose origin remains unclear. Here, we propose a new mechanism that could generate seismic discontinuities beneath subduction zones with depth distributions consistent with some of the observed mid-mantle reflectors. By coupling thermo-mechanical subduction models with pressure- dependent fabric calculations, we show that gradual slip transitions in bridgmanite with depth can manifest anisotropic discontinuities near 1000 km, which can deepen depending on the extent of accumulated deformation. This discontinuity is most pronounced in regions of strong slab-driven flow as revealed by its reflection coefficients, the strength of which varies with distance and azimuth. While our models predict ∼1.5% contrast in fast versus slow shear wave velocities in terms of radial anisotropy, our full waveform simulations show that the discontinuity is detectable with array seismological methods. These results suggest that mid-mantle reflectors near subduction zones may be strain-induced, providing an additional mechanism that links mantle flow, mineral physics, and seismic observations. Earth and environmental sciences/Solid Earth sciences/Seismology Earth and environmental sciences/Solid Earth sciences/Geodynamics Earth and environmental sciences/Solid Earth sciences/Mineralogy Earth and environmental sciences/Solid Earth sciences/Geophysics Full Text Additional Declarations There is NO Competing Interest. Supplementary Files revisedSupplementaryMaterialv5.pdf Supplementary Material for "Mid-mantle discontinuities beneath subduction zones linked to depth-dependent deformation of bridgmanite" 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-7039328","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":622255373,"identity":"8d00e470-fa2f-477a-918e-95fc3e0d64d4","order_by":0,"name":"John Keith Magali","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYBACxh4ILcPG3gCkDCyI18LDxnMApEWCCGt4YJREAogmQgtzzxnTDT9+2fHwST6/uuFHgQQDf3t3An6H9faY3eztS+Zhk84pu9kDdJjEmbMb8GvpZ0u7wdvDDNKSdoMHqMVAIpewlpt/e+p52CTPpN38Q5SW3uZjt3l+HOZhk2AHMojS0nP42G3ZhuPAQM5huy1jIMFD0C+GPYltN9/8qZaTbz/+DMiwkeNv7yWgpQFkVRuIyWMAJvEqBwF5MPkHRLA/IKh6FIyCUTAKRiYAALLYReAE4sHgAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-8574-7098","institution":"University of Muenster","correspondingAuthor":true,"prefix":"","firstName":"John","middleName":"Keith","lastName":"Magali","suffix":""},{"id":622255374,"identity":"be2a1062-f1bf-4539-9fcd-4b1082fe6f52","order_by":1,"name":"Sébastien Merkel","email":"","orcid":"https://orcid.org/0000-0003-2767-581X","institution":"Univ. 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Bulk of the lower mantle is widely regarded as well-mixed but recent seismic observations suggest structures at mid-mantle depths whose origin remains unclear. Here, we propose a new mechanism that could generate seismic discontinuities beneath subduction zones with depth distributions consistent with some of the observed mid-mantle reflectors. By coupling thermo-mechanical subduction models with pressure- dependent fabric calculations, we show that gradual slip transitions in bridgmanite with depth can manifest anisotropic discontinuities near 1000 km, which can deepen depending on the extent of accumulated deformation. This discontinuity is most pronounced in regions of strong slab-driven flow as revealed by its reflection coefficients, the strength of which varies with distance and azimuth. While our models predict ∼1.5% contrast in fast versus slow shear wave velocities in terms of radial anisotropy, our full waveform simulations show that the discontinuity is detectable with array seismological methods. These results suggest that mid-mantle reflectors near subduction zones may be strain-induced, providing an additional mechanism that links mantle flow, mineral physics, and seismic observations.","manuscriptTitle":"Mid-mantle discontinuities beneath subduction zones linked to depth-dependent deformation of bridgmanite","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-14 09:32:32","doi":"10.21203/rs.3.rs-7039328/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5786e33a-949c-40f1-a2d1-8a5cd605adfa","owner":[],"postedDate":"April 14th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"This content is not available.","date":"2026-05-06T21:49:27+00:00","index":2,"fulltext":"This content is not available."}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":66217458,"name":"Earth and environmental sciences/Solid Earth sciences/Seismology"},{"id":66217459,"name":"Earth and environmental sciences/Solid Earth sciences/Geodynamics"},{"id":66217460,"name":"Earth and environmental sciences/Solid Earth sciences/Mineralogy"},{"id":66217461,"name":"Earth and environmental sciences/Solid Earth sciences/Geophysics"}],"tags":[],"updatedAt":"2026-04-14T11:22:22+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-14 09:32:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7039328","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7039328","identity":"rs-7039328","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}