Diversity and biolithostratigraphy of foraminifera from the Upper Eocene–Lower Oligocene Malishka section, Armenia

Diversity and biolithostratigraphy of foraminifera from the Upper Eocene–Lower Oligocene Malishka section, Armenia | 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 Research Article Diversity and biolithostratigraphy of foraminifera from the Upper Eocene–Lower Oligocene Malishka section, Armenia Taron Grigoryan, Lilit Sahakyan, Elena Zakrevskaya, Pavel Fokin, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6127696/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 29 Jan, 2026 Read the published version in Palaeobiodiversity and Palaeoenvironments → Version 1 posted 5 You are reading this latest preprint version Abstract The Eocene-Oligocene transition marks significant global climatic changes, coinciding with the closure of the southern Neotethys. The Priabonian-Rupelian transition in the Malishka section of the Vayots-Dzor area is represented by alternation of shallow-water limestones-sandstones with hemipelagic claystones and siltstones. These facies provide essential evidence for revising planktonic and benthic foraminiferal biozonations and analyzing the sedimentological characteristics of the section. In Malishka section turbidity currents are inferred from flute cast structures, reverse-graded bedding, and pebble-bearing limestone in the Late Eocene, which was followed by greywacke sedimentation in the Early Oligocene. Larger benthic foraminifers (LBF), fragments of solitary and colonial corals, red algae, echinoderms, bryozoans, bivalves and rare carbonate sponges, together with planktonic foraminifera (PF) in limestones suggest transport from the euphotic zone. The LBF exhibit significant abundance and diversity in the upper Eocene sediments, with about 20 species and subspecies of orthophragminids (Discocyclina, Orbitoclypeus, Asterocyclina) and nummulitids (Nummulites, Operculina, Heterostegina, Spiroclypeus). The Oligocene LBF are represented by only five species of Nummulites. The last occurrences of orthophragminids were observed before the Eocene/Oligocene boundary, as defined by PF zonation. About 40 species of PF are identified in the claystones and siltstones of uppermost Eocene and lower Oligocene. The 46-meter-thick Malishka section, spanning the Eocene/Oligocene boundary, corresponds to the PF zones E16, O1, O2 and O3 as well as the LBF zones SBZ20 and SBZ21. The study of PF and LBF from the Malishka section facilitated the correlation of bioevents between these two groups. Stratigraphy Lithofacies Eocene-Oligocene Boundary Microfossils Nummulites Full Text Cite Share Download PDF Status: Published Journal Publication published 29 Jan, 2026 Read the published version in Palaeobiodiversity and Palaeoenvironments → Version 1 posted Editorial decision: Major Revisions Needed 18 Jun, 2025 Reviewers agreed at journal 25 Mar, 2025 Reviewers invited by journal 25 Mar, 2025 Editor assigned by journal 04 Mar, 2025 First submitted to journal 02 Mar, 2025 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. 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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-6127696","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":433888730,"identity":"08a6db68-3254-4d70-b7d3-0551b556113c","order_by":0,"name":"Taron Grigoryan","email":"","orcid":"","institution":"Institute of Geological Sciences","correspondingAuthor":false,"prefix":"","firstName":"Taron","middleName":"","lastName":"Grigoryan","suffix":""},{"id":433888731,"identity":"ba072ec0-c958-4049-8409-a6f0e80817c3","order_by":1,"name":"Lilit Sahakyan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYBACPmbmhgNAOoGBB8StYGAwIKSFjZmx4cABuJYzxGhhYGxggGthbCNGCztj4+EPf+zy+HvOGH4unHdY3py9+QDDj4pt+B12sC25WOJsj7H0zG2HDXf2HEtg7Dlzm4CWBubEhvM8BtK82w4zbriRY8DM2EZAy4E/9Ynzz/MY/+adc9ieSC1shxM3nO0xk+ZtADKI0nK27XjixjPHyqx5jqUnbzhzLOEgPr/w8x8+/KHiT3XivDPJm2/z1FjbbjjefPDBjwrcWpAAByhGmsHMA8SoBwL2B0CijkjFo2AUjIJRMJIAABPYYHkRAniiAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-5539-5690","institution":"National Academy of Sciences","correspondingAuthor":true,"prefix":"","firstName":"Lilit","middleName":"","lastName":"Sahakyan","suffix":""},{"id":433888732,"identity":"58729d7a-959f-4f96-afea-ea128b103e73","order_by":2,"name":"Elena Zakrevskaya","email":"","orcid":"","institution":"MUSEUM","correspondingAuthor":false,"prefix":"","firstName":"Elena","middleName":"","lastName":"Zakrevskaya","suffix":""},{"id":433888733,"identity":"15882011-15b3-4f4b-8113-abb148ccf6b2","order_by":3,"name":"Pavel Fokin","email":"","orcid":"","institution":"Moscow State University: Moskovskij gosudarstvennyj universitet imeni M V Lomonosova","correspondingAuthor":false,"prefix":"","firstName":"Pavel","middleName":"","lastName":"Fokin","suffix":""},{"id":433888734,"identity":"bd69a20d-bd76-43c7-80d4-319934475e3b","order_by":4,"name":"Ara Avagyan","email":"","orcid":"","institution":"Institute of Geological Sciences","correspondingAuthor":false,"prefix":"","firstName":"Ara","middleName":"","lastName":"Avagyan","suffix":""}],"badges":[],"createdAt":"2025-02-28 10:32:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6127696/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6127696/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s12549-025-00692-z","type":"published","date":"2026-01-29T15:59:12+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":101691620,"identity":"06f6b6f5-2547-4322-aef0-cdc6fb9191b1","added_by":"auto","created_at":"2026-02-02 16:14:32","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1102911,"visible":true,"origin":"","legend":"","description":"","filename":"Grigoryanetal2025.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6127696/v1_covered_a3cd75ac-dd07-4738-a7bd-50207af79768.pdf"}],"financialInterests":"","formattedTitle":"Diversity and biolithostratigraphy of foraminifera from the Upper Eocene–Lower Oligocene Malishka section, Armenia","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"palaeobiodiversity-and-palaeoenvironments","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pbpe","sideBox":"Learn more about [Palaeobiodiversity and Palaeoenvironments](https://www.springer.com/journal/12549)","snPcode":"12549","submissionUrl":"https://www.editorialmanager.com/pbpe/default2.aspx","title":"Palaeobiodiversity and Palaeoenvironments","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Stratigraphy, Lithofacies, Eocene-Oligocene Boundary, Microfossils, Nummulites","lastPublishedDoi":"10.21203/rs.3.rs-6127696/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6127696/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The Eocene-Oligocene transition marks significant global climatic changes, coinciding with the closure of the southern Neotethys. 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