Trivalent Titanium in High-Titanium Lunar Ilmenite

Trivalent Titanium in High-Titanium Lunar Ilmenite | 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 Trivalent Titanium in High-Titanium Lunar Ilmenite Advik Vira, Katherine Burgess, Mengkun Tian, Emily First, Keyes Eames, and 11 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7190245/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Mar, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Lunar mare basalts are often rich in titanium, hosted predominantly within the mineral ilmenite (Fe 2+ Ti 4+ O 3 ). Of all Apollo samples returned from the Moon, only two are olivine-free basalts, making them of interest for their potential to constrain models of lunar evolution. Here, we use electron microscopy and electron energy loss spectroscopy (EELS) to investigate ilmenite in one of these samples: Apollo rock 75035. A key finding is that 75035 ilmenite is itself enriched in Ti, beyond the end member of the conventional solid solution series. Using energy loss near-edge spectroscopy (ELNES), we determine that the excess Ti is reduced to trivalent Ti, with Ti 3+ mole fraction ~ 0.07. This discovery confirms a longstanding hypothesis based on the Moon's reducing environment. Its impact for lunar models comes through the implied oxygen fugacity during crystallization of 75035, which we estimate to be below the iron-wüstite buffer (IW): ∆IW ≤ −1.5. Our research also suggests that Ti 3+ -bearing ilmenite could serve as a single-phase oxybarometer for the reducing conditions found on many planetary bodies. Earth and environmental sciences/Planetary science/Geochemistry Earth and environmental sciences/Planetary science/Mineralogy Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryVideo1.avi Supplementary Video 1 SupplementaryVideo2.avi Supplementary Video 2 HighTiIlmeniteSupplemental.pdf Supplementary Material Cite Share Download PDF Status: Published Journal Publication published 27 Mar, 2026 Read the published version in Nature Communications → 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-7190245","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":499963154,"identity":"bf8cb61e-5cc1-4eee-b17d-3cd3747ac3d3","order_by":0,"name":"Advik 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Of all Apollo samples returned from the Moon, only two are olivine-free basalts, making them of interest for their potential to constrain models of lunar evolution. Here, we use electron microscopy and electron energy loss spectroscopy (EELS) to investigate ilmenite in one of these samples: Apollo rock 75035. A key finding is that 75035 ilmenite is itself enriched in Ti, beyond the end member of the conventional solid solution series. Using energy loss near-edge spectroscopy (ELNES), we determine that the excess Ti is reduced to trivalent Ti, with Ti\u003csup\u003e3+\u003c/sup\u003e mole fraction ~ 0.07. This discovery confirms a longstanding hypothesis based on the Moon's reducing environment. Its impact for lunar models comes through the implied oxygen fugacity during crystallization of 75035, which we estimate to be below the iron-wüstite buffer (IW): ∆IW ≤ −1.5. Our research also suggests that Ti\u003csup\u003e3+\u003c/sup\u003e -bearing ilmenite could serve as a single-phase oxybarometer for the reducing conditions found on many planetary bodies.","manuscriptTitle":"Trivalent Titanium in High-Titanium Lunar Ilmenite","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-25 02:44:41","doi":"10.21203/rs.3.rs-7190245/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":"ea1a3944-b287-4338-bd3a-b46f70119f10","owner":[],"postedDate":"August 25th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":53109432,"name":"Earth and environmental sciences/Planetary science/Geochemistry"},{"id":53109433,"name":"Earth and environmental sciences/Planetary science/Mineralogy"}],"tags":[],"updatedAt":"2026-03-28T07:11:53+00:00","versionOfRecord":{"articleIdentity":"rs-7190245","link":"https://doi.org/10.1038/s41467-026-69770-w","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2026-03-27 04:00:00","publishedOnDateReadable":"March 27th, 2026"},"versionCreatedAt":"2025-08-25 02:44:41","video":"","vorDoi":"10.1038/s41467-026-69770-w","vorDoiUrl":"https://doi.org/10.1038/s41467-026-69770-w","workflowStages":[]},"version":"v1","identity":"rs-7190245","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7190245","identity":"rs-7190245","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}