{
  "abstract": "Zircons interpreted to be of syn-volcanic origin recovered from the lower greenschist “black and white banded” Bhitardari chert, Eastern Iron Ore greenstone belt, Singhbhum craton, India, yield a 207 Pb/ 206 Pb zircon age of 3497 ± 5 Ma ( 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 δ 13 C CM of both modes in the Bhitardari chert yield a value of −30.9‰, which we interpret as reflecting a biogenic origin. This represents the documentation of a directly dated, CM-bearing, Paleoarchean rock with δ 13 C CM 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.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "name": "Trisrota Chaudhuri"
    },
    {
      "name": "T. Mark Harrison"
    },
    {
      "name": "Elizabeth A. Bell"
    },
    {
      "name": "Mark van Zuilen"
    },
    {
      "name": "Lena Thomas"
    },
    {
      "name": "Nouf Al Alawi"
    },
    {
      "name": "Rajat Mazumder"
    },
    {
      "name": "Stefan Lalonde"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1xgbh1kp60as0.bib",
  "cited_by": 1,
  "doi": "10.1073/pnas.2617912123",
  "fulltext_url": null,
  "id": "1xgbh1kp60as0",
  "issns": [
    "0027-8424",
    "1091-6490"
  ],
  "landing_url": "https://hal.science/hal-05854077v1",
  "language": "en",
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.sdu"
    ],
    [
      "openalex",
      "1908|Geological and Geochemical Analysis"
    ]
  ],
  "openalex": "W7203614744",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-05",
  "publisher": "National Academy of Sciences",
  "ris": "https://research.draconitic.com/paper/1xgbh1kp60as0.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T12:20:44Z",
      "native_id": "hal-05854077",
      "source": "hal",
      "url": "https://hal.science/hal-05854077v1"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "openalex:1908|Geological and Geochemical Analysis",
      "subfield": "geophysics"
    }
  ],
  "title": "Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India",
  "title_text": "Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T12:20:25Z",
  "url": "https://research.draconitic.com/paper/1xgbh1kp60as0",
  "venue": "Proceedings of the National Academy of Sciences of the United States of America",
  "versions": []
}