Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation

Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation | 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 Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation Grace Chinwendu Isitoah, Theresa Nkechi Obiekezie This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9447201/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study, titled “Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation,” examines the subsurface electrical conductivity structure beneath Lagos (6.48° N, 3.27° E), Abidjan (5.35° N, − 3.08° E), Ilorin (8.50° N, 4.68° E), and Abuja (10.5° N, 7.55° E) in 2011. Geomagnetic data from the AMBER and MAGDAS arrays under quiet solar conditions were analyzed using Gauss spherical harmonic analysis to separate internal and external fields, followed by transfer-function methods to derive conductivity–depth profiles. The resulting models reveal marked spatial variability in lithospheric and upper mantle electrical properties across West Africa, reflecting differences in thermal regime, composition, and tectonic setting. Beneath Lagos, conductivity increases from ~ 0.203 S/m at 112.60 km to a peak of ~ 0.720 S/m at 612.58 km, with multiple peaks in the lower crust and upper mantle. These elevated values indicate partial melts or hydrated zones, suggesting a thermally active mantle and strong crust–mantle coupling. The Abuja profile (200–2000 km) displays an initial rise through the upper mantle, a pronounced decrease between ~ 800 and 1600 km, and a subsequent increase at greater depths, consistent with mantle heterogeneity and pressure-induced mineral phase transitions. Abidjan exhibits relatively low conductivity, indicative of a resistive lithosphere and cooler upper mantle. The poorly defined lithosphere–asthenosphere boundary and gradual conductivity increase suggest a thick, stable lithosphere with limited partial melting. At Ilorin, the shallow profile (15–60 km) shows a heterogeneous crust: a resistive upper crust, a variable mid-crust with localized conductive zones, and a moderately conductive lower crust, influenced by fluid content and mineral composition. Collectively, these 2011 models highlight the complex, regionally variable geoelectric structure of West Africa. Lagos displays signatures of thermal and possibly magmatic activity, Abidjan reflects stable resistive conditions, Abuja reveals deep mantle transitions, and Ilorin emphasizes crustal heterogeneity. The findings provide insights into lithospheric thickness, mantle dynamics, and the thermal-compositional controls on electrical conductivity. Earth and environmental sciences/Planetary science Earth and environmental sciences/Solid earth sciences AMBER array MAGDAS array crust-mantle structure Electrical conductivity upper mantle transfer functions Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted 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. 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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-9447201","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":625324047,"identity":"2b057b94-ce41-4ff5-a09f-ab9b6984d797","order_by":0,"name":"Grace Chinwendu Isitoah","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYBACNgbGBiB1gIEfxEsoIE5LYwNIiyRIZ4IBcRYxgrUYHACxidHCx3+4/cGHmjt2m8+vTvzwwIBBnl/sAAGHSSQ2Ns449ix52423myWADjOcOTuBkBbGxmYetsPJZjfObgBpSTC4TUgL/0Ggln+Hk41nnN38gzgtDImNzbxth+0M+Hu3EWkL0C8zZ/YdTpC4wbvNIsFAgrBf5PuPP/jw4dthe/7+s5tv/qiwkeeXJqAFBhIbJMAqJYhTDgL2DPwHiFc9CkbBKBgFIwsAAIKGScMiyuBXAAAAAElFTkSuQmCC","orcid":"","institution":"Nnamdi Azikiwe University","correspondingAuthor":true,"prefix":"","firstName":"Grace","middleName":"Chinwendu","lastName":"Isitoah","suffix":""},{"id":625324048,"identity":"171ca633-09b4-4bc8-860c-bbbb3dda926d","order_by":1,"name":"Theresa Nkechi Obiekezie","email":"","orcid":"","institution":"Nnamdi Azikiwe University","correspondingAuthor":false,"prefix":"","firstName":"Theresa","middleName":"Nkechi","lastName":"Obiekezie","suffix":""}],"badges":[],"createdAt":"2026-04-17 09:38:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9447201/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9447201/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":109443291,"identity":"44ca74b2-57b5-4fbc-b44e-e2fa080ca9e5","added_by":"auto","created_at":"2026-05-18 07:41:41","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":512190,"visible":true,"origin":"","legend":"","description":"","filename":"CrustandMantleVariationalongtheWestAfrcaLongitude21.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9447201/v1_covered_e5506b53-0cfe-4b79-9150-f136ab60b67c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"AMBER array, MAGDAS array, crust-mantle structure, Electrical conductivity, upper mantle, transfer functions","lastPublishedDoi":"10.21203/rs.3.rs-9447201/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9447201/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study, titled \u0026ldquo;Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation,\u0026rdquo; examines the subsurface electrical conductivity structure beneath Lagos (6.48\u0026deg; N, 3.27\u0026deg; E), Abidjan (5.35\u0026deg; N, \u0026minus;\u0026thinsp;3.08\u0026deg; E), Ilorin (8.50\u0026deg; N, 4.68\u0026deg; E), and Abuja (10.5\u0026deg; N, 7.55\u0026deg; E) in 2011. Geomagnetic data from the AMBER and MAGDAS arrays under quiet solar conditions were analyzed using Gauss spherical harmonic analysis to separate internal and external fields, followed by transfer-function methods to derive conductivity\u0026ndash;depth profiles. The resulting models reveal marked spatial variability in lithospheric and upper mantle electrical properties across West Africa, reflecting differences in thermal regime, composition, and tectonic setting. Beneath Lagos, conductivity increases from ~\u0026thinsp;0.203 S/m at 112.60 km to a peak of ~\u0026thinsp;0.720 S/m at 612.58 km, with multiple peaks in the lower crust and upper mantle. These elevated values indicate partial melts or hydrated zones, suggesting a thermally active mantle and strong crust\u0026ndash;mantle coupling. The Abuja profile (200\u0026ndash;2000 km) displays an initial rise through the upper mantle, a pronounced decrease between ~\u0026thinsp;800 and 1600 km, and a subsequent increase at greater depths, consistent with mantle heterogeneity and pressure-induced mineral phase transitions. Abidjan exhibits relatively low conductivity, indicative of a resistive lithosphere and cooler upper mantle. The poorly defined lithosphere\u0026ndash;asthenosphere boundary and gradual conductivity increase suggest a thick, stable lithosphere with limited partial melting. At Ilorin, the shallow profile (15\u0026ndash;60 km) shows a heterogeneous crust: a resistive upper crust, a variable mid-crust with localized conductive zones, and a moderately conductive lower crust, influenced by fluid content and mineral composition. Collectively, these 2011 models highlight the complex, regionally variable geoelectric structure of West Africa. Lagos displays signatures of thermal and possibly magmatic activity, Abidjan reflects stable resistive conditions, Abuja reveals deep mantle transitions, and Ilorin emphasizes crustal heterogeneity. The findings provide insights into lithospheric thickness, mantle dynamics, and the thermal-compositional controls on electrical conductivity.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e","manuscriptTitle":"Determination of crust-mantle conductivity variation on West Africa longitudes using solar quiet ionospheric current variation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-21 03:30:56","doi":"10.21203/rs.3.rs-9447201/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1d875147-bc1c-41ff-b9c4-5b3b49fb240b","owner":[],"postedDate":"April 21st, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Rejected","date":"2026-05-18T07:36:50+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-16T00:06:03+00:00","index":47,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-12T15:42:38+00:00","index":46,"fulltext":""},{"type":"reviewerAgreed","content":"4672882762511487225475491910372333572","date":"2026-04-29T14:19:42+00:00","index":45,"fulltext":""},{"type":"reviewerAgreed","content":"78065923498182819177686770019139605612","date":"2026-04-29T04:08:07+00:00","index":44,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":66562765,"name":"Earth and environmental sciences/Planetary science"},{"id":66562766,"name":"Earth and environmental sciences/Solid earth sciences"}],"tags":[],"updatedAt":"2026-05-18T07:41:29+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-21 03:30:56","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9447201","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9447201","identity":"rs-9447201","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}