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Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2026,8,25]]},"abstract":"<jats:p>\n                    Zircons interpreted to be of syn-volcanic origin recovered from the lower greenschist \u201cblack and white banded\u201d Bhitardari chert, Eastern Iron Ore greenstone belt, Singhbhum craton, India, yield a\n                    <jats:sup>207<\/jats:sup>\n                    Pb\/\n                    <jats:sup>206<\/jats:sup>\n                    Pb zircon age of 3497 \u00b1 5 Ma (\n                    <jats:italic toggle=\"yes\">n<\/jats:italic>\n                    = 4; MSWD = 1.2). This chert contains abundant carbonaceous matter (CM) that occurs in two textural modes: 1) ultrafine laminae distributed within the matrix and 2) graphite flakes in late quartz veins. Bulk \u03b4\n                    <jats:sup>13<\/jats:sup>\n                    C\n                    <jats:sub>CM<\/jats:sub>\n                    of both modes in the Bhitardari chert yield a value of \u221230.9\u2030, which we interpret as reflecting a biogenic origin. This represents the documentation of a directly dated, CM-bearing, Paleoarchean rock with \u03b4\n                    <jats:sup>13<\/jats:sup>\n                    C\n                    <jats:sub>CM<\/jats:sub>\n                    diagnostic of biologic activity. The observed isotopic compositions are consistent with the rise of relatively sophisticated metabolic mechanisms (e.g., Calvin cycle) by 3.5 Ga.\n                  <\/jats:p>","DOI":"10.1073\/pnas.2617912123","type":"journal-article","created":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T19:03:46Z","timestamp":1786993426000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":1,"title":["Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India"],"prefix":"10.1073","volume":"123","author":[{"given":"Trisrota","family":"Chaudhuri","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00nthx533","id-type":"ROR","asserted-by":"publisher"}],"name":"Secondary Ion Mass Spectrometer (SIMS) Laboratory, Geological Survey of India","place":["Kolkata, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1557-2891","authenticated-orcid":false,"given":"T. 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Jodder \u201cThe geology of the Daitari Greenstone Belt Singhbhum Craton India: Insights into early life 3.5 Ga ago \u201d PhD thesis University of Johannesburg Johannesburg South Africa (2021); Available from https:\/\/hdl.handle.net\/10210\/477262."},{"key":"e_1_3_4_45_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.earscirev.2022.104122"},{"key":"e_1_3_4_46_2","unstructured":"J. A. Dunn A. K. Dey The Geology and Petrology of Eastern Singhbhum and Surrounding Areas in Memoirs of the Geological Survey of India (Government of India Press 1942) pp. 281\u2013456."},{"key":"e_1_3_4_47_2","doi-asserted-by":"publisher","DOI":"10.1007\/s12040-022-02011-y"},{"key":"e_1_3_4_48_2","doi-asserted-by":"crossref","unstructured":"C. S. Palenik L. Nasdala R. C. Ewing Radiation damage in zircon. Am. 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Hickman-Lewis B. Cavalazzi F. Foucher F. Westall Most ancient evidence for life in the Barberton greenstone belt: Microbial mats and biofabrics of the \u223c3.47 Ga Middle Marker horizon. 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