1 Bernard, S. & Papineau, D. Graphitic carbons and biosignatures. Elements 10, 435–440 (2014)

2 van Zuilen, M. A., Lepland, A. & Arrhenius, G. Reassessing the evidence for the earliest traces of life. Nature 418, 627–630 (2002)

3 Ohtomo, Y., Kakegawa, T., Ishida, A., Nagase, T. & Rosing, M. T. Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks. Nat. Geosci. 7, 25–28 (2013)

4 Rosing, M. T. 13C-depleted carbon microparticles in >3700-Ma sea-floor sedimentary rocks from West Greenland. Science 283, 674–676 (1999)

5 McCollom, T. M. & Seewald, J. S. Abiotic synthesis of organic compounds in deep-sea hydrothermal environments. Chem. Rev. 107, 382–401 (2007)

6 Mojzsis, S. J. et al. Evidence for life on Earth before 3,800 million years ago. Nature 384, 55–59 (1996)

7 Papineau, D. et al. Ancient graphite in the Eoarchean quartz-pyroxene rocks from Akilia in southern West Greenland II: isotopic and chemical compositions and comparison with Paleoproterozoic banded iron formations. Geochim. Cosmochim. Acta 74, 5884–5905 (2010)

8 Papineau, D. et al. Ancient graphite in the Eoarchean quartz–pyroxene rocks from Akilia in southern West Greenland I: petrographic and spectroscopic characterization. Geochim. Cosmochim. Acta 74, 5862–5883 (2010)

9 Lepland, A., van Zuilen, M. A. & Philippot, P. Fluid-deposited graphite and its geobiological implications in Early Archean gneiss from Akilia, Greenland. Geobiology 9, 2–9 (2011)

10 Papineau, D. et al. Young poorly crystalline graphite in the >3.8-Gyr-old Nuvvuagittuq banded iron formation. Nat. Geosci. 4, 376–379 (2011)

11 O’Neil, J., Francis, D. & Carlson, R. W. Implications of the Nuvvuagittuq greenstone belt for the formation of Earth’s early crust. J. Petrol. 52, 985–1009 (2011)

12 Cates, N. L., Ziegler, K., Schmitt, A. K. & Mojzsis, S. J. Reduced, reused and recycled: detrital zircons define a maximum age for the Eoarchean (ca. 3750–3780 Ma) Nuvvuagittuq supracrustal belt, Québec (Canada). Earth Planet. Sci. Lett. 362, 283–293 (2013)

13 Darling, J. R. et al. Eoarchean to Neoarchean evolution of the Nuvvuagittuq supracrustal belt: new insights from U-Pb zircon geochronology. Am. J. Sci. 313, 844–876 (2013)

14 O’Neil, J., Carlson, R. W., Paquette, J.-L. & Francis, D. Formation age and metamorphic history of the Nuvvuagittuq greenstone belt. Precambr. Res. 220–221, 23–44 (2012)

15 O’Neil, J., Carlson, R. W., Francis, D. & Stevenson, R. K. Neodymium-142 evidence for Hadean mafic crust. Science 321, 1828–1831 (2008)

16 Mloszewska, A. M. et al. The composition of Earth’s oldest iron formations: the Nuvvuagittuq supracrustal belt (Québec, Canada). Earth Planet. Sci. Lett. 317–318, 331–342 (2012)

17 O’Neil, J. et al. in Earth’s Oldest Rocks Vol. 15 (eds van Kranendonk, M. J., Smithies, R. H. & Bennett, V. C. ) 219–250 (Elsevier, 2007)

18 Dauphas, N., Cates, N. L., Mojzsis, S. J. & Busigny, V. Identification of chemical sedimentary protoliths using iron isotopes in the >3750 Ma Nuvvuagittuq supracrustal belt, Canada. Earth Planet. Sci. Lett. 254, 358–376 (2007)

19 Mloszewska, A. M. et al. Chemical sedimentary protoliths in the >3.75Ga Nuvvuagittuq supracrustal belt (Québec, Canada). Gondwana Res. 23, 574–594 (2013)

20 Cates, N. L. & Mojzsis, S. J. Metamorphic zircon, trace elements and Neoarchean metamorphism in the ca. 3.75 Ga Nuvvuagittuq supracrustal belt, Québec (Canada). Chem. Geol. 261, 99–114 (2009)

21 Edwards, K. J. et al. Ultra-diffuse hydrothermal venting supports Fe-oxidizing bacteria and massive umber deposition at 5000 m off Hawaii. ISME J. 5, 1748–1758 (2011)

22 Juniper, S. K. & Fouquet, Y. Filamentous iron-silica deposits from modern and ancient hydrothermal sites. Can. Mineral. 26, 859–869 (1988)

23 Li, J. et al. Microbial diversity and biomineralization in low-temperature hydrothermal iron-silica-rich precipitates of the Lau Basin hydrothermal field. FEMS Microbiol. Ecol. 81, 205–216 (2012)

24 Boyd, T. D. & Scott, S. D. Microbial and hydrothermal aspects of ferric oxyhydroxides and ferrosic hydroxides: the example of Franklin Seamount, western Woodlark Basin, Papua New Guinea. Geochem. Trans. 2, 45 (2001)

25 Emerson, D. & Moyer, C. L. Neutrophilic Fe-oxidizing bacteria are abundant at the Loihi Seamount hydrothermal vents and play a major role in Fe oxide deposition. Appl. Environ. Microbiol. 68, 3085–3093 (2002)

26 Hein, J. R., Clague, D. A., Koski, R. A., Embley, R. W. & Dunham, R. E. Metalliferous sediment and a silica-hematite deposit within the Blanco Fracture Zone, northeast Pacific. Mar. Georesour. Geotechnol. 26, 317–339 (2008)

27 Grenne, T. & Slack, J. F. Bedded jaspers of the Ordovician Løkken ophiolite, Norway: seafloor deposition and diagenetic maturation of hydrothermal plume-derived silica-iron gels. Miner. Depos. 38, 625–639 (2003)

28 Little, C. T. S., Glynn, S. E. J. & Mills, R. A. Four-hundred-and-ninety-million-year record of bacteriogenic iron oxide precipitation at sea-floor hydrothermal vents. Geomicrobiol. J. 21, 415–429 (2004)

29 Duhig, N. C., Stolz, J., Davidson, G. J. & Large, R. R. Cambrian microbial and silica gel textures in silica iron exhalites from the Mount Windsor volcanic belt, Australia: their petrography, chemistry, and origin. Econ. Geol. 87, 764–784 (1992)

30 Krepski, S. T., Emerson, D., Hredzak-Showalter, P. L., Luther, G. W., III & Chan, C. S. Morphology of biogenic iron oxides records microbial physiology and environmental conditions: toward interpreting iron microfossils. Geobiology 11, 457–471 (2013)

31 Picard, A., Obst, M., Schmid, G., Zeitvogel, F. & Kappler, A. Limited influence of Si on the preservation of Fe mineral-encrusted microbial cells during experimental diagenesis. Geobiology 14, 276–292 (2016)

32 Chi Fru, E. et al. Biogenicity of an early Quaternary iron formation, Milos Island, Greece. Geobiology 13, 225–244 (2015)

33 Little, C. T. S., Herrington, R., Haymon, R. & Danelian, T. Early Jurassic hydrothermal vent community from the Franciscan Complex, San Rafael Mountains. Calif. Geol. 27, 167–170 (1999)

34 Ayupova, N. R. & Maslennikov, V. V. Biomorphic textures in the ferruginous-siliceous rocks of massive sulfide-bearing paleohydrothermal fields in the Urals. Lithol. Miner. Resour. 48, 438–455 (2013)

35 Sun, Z. et al. Generation of hydrothermal Fe-Si oxyhydroxide deposit on the southwest Indian Ridge and its implication for the origin of ancient banded iron formations. J. Geophys. Res. Biogeosci. 120, 187–203 (2015)

36 Ayupova, N. R., Maslennikov, V. V., Sadykov, S. A., Maslennikova, S. P. & Danyushevsky, L. V. in Biogenic–Abiogenic Interactions in Natural and Anthropogenic Systems (eds Frank-Kamenetskaya, V. O., Panova, G. E. & Vlasov, Y. D. ) 109–122 (Springer, 2016)

37 Campbell, K. A. et al. Tracing biosignature preservation of geothermally silicified microbial textures into the geological record. Astrobiology 15, 858–882 (2015)

38 Parenteau, M. N. & Cady, S. L. Microbial biosignatures in iron-mineralized phototrophic mats at Chocolate Pots Hot Springs, Yellowstone National Park, United States. Palaios 25, 97–111 (2010)

39 Thompson, K. J., Lliros, M., Michiels, C., Kenward, P. & Crowe, S. in 2014 GSA Annual Meeting Vol. 46, 401 (Geol. Soc. Am. Abstracts with Programs, 2014)

40 Köhler, I., Konhauser, K. O., Papineau, D., Bekker, A. & Kappler, A. Biological carbon precursor to diagenetic siderite with spherical structures in iron formations. Nat. Commun. 4, 1741 (2013)

41 Sun, Z. et al. Mineralogical characterization and formation of Fe-Si oxyhydroxide deposits from modern seafloor hydrothermal vents. Am. Mineral. 98, 85–97 (2012)

42 Heaney, P. J. & Veblen, D. R. An examination of spherulitic dubiomicrofossils in Precambrian banded iron formations using the transmission electron microscope. Precambr. Res. 49, 355–372 (1991)

43 Beyssac, O., Goffe, B., Chopin, C. & Rouzaud, J. N. Raman spectra of carbonaceous material in metasediments: a new geothermometer. J. Metamorph. Geol. 20, 859–871 (2002)

44 Heimann, A. et al. Fe, C, and O isotope compositions of banded iron formation carbonates demonstrate a major role for dissimilatory iron reduction in ~2.5 Ga marine environments. Earth Planet. Sci. Lett. 294, 8–18 (2010)

45 Cappellen, P. V. & Berner, R. A. A mathematical model for the early diagenesis of phosphorus and fluorine in marine sediments: apatite precipitation. Am. J. Sci. 288, 289–333 (1988)

46 Papineau, D. et al. Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India. Geobiology 14, 3–32 (2016)

47 Brasier, A. T., Rogerson, M. R., Mercedes-Martin, R., Vonhof, H. B. & Reijmer, J. J. G. A test of the biogenicity criteria established for microfossils and stromatolites on Quaternary tufa and speleothem materials formed in the “Twilight Zone” at Caerwys, UK. Astrobiology 15, 883–900 (2015)

48 Zaikin, A. N. & Zhabotinsky, A. M. Concentration wave propagation in two-dimensional liquid-phase self-oscillating system. Nature 225, 535–537 (1970)

49 Smith, A. J. B., Beukes, N. J., Gutzmer, J., Johnson, C. M. & Czaja, A. D. in Goldschmidt. 2384 (Mineralogical Society, 2012)

50 Walter, M. R., Goode, A. D. T. & Hall, W. D. M. Microfossils from a newly discovered Precambrian stromatolitic iron formation in Western Australia. Nature 261, 221–223 (1976)

51 Bolhar, R., Kamber, B. S., Moorbath, S., Fedo, C. M. & Whitehouse, M. J. Characterisation of early Archaean chemical sediments by trace element signatures. Earth Planet. Sci. Lett. 222, 43–60 (2004)

52 Wirth, R. Focused Ion Beam (FIB) combined with SEM and TEM: advanced analytical tools for studies of chemical composition, microstructure and crystal structure in geomaterials on a nanometre scale. Chem. Geol. 261, 217–229 (2009)

53 Zega, T. J., Nittler, L. R., Busemann, H., Hoppe, P. & Stroud, R. M. Coordinated isotopic and mineralogic analyses of planetary materials enabled by in situ lift-out with a focused ion beam scanning electron microscope. Meteorit. Planet. Sci. 42, 1–14 (2007)

54 Jackson, S. E., Pearson, N. J., Griffin, W. L. & Belousova, E. A. The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U–Pb zircon geochronology. Chem. Geol. 211, 47–69 (2004)

55 Chew, D. M., Sylvester, P. J. & Tubrett, M. N. U-Pb and Th-Pb dating of apatite by LA-ICPMS. Chem. Geol. 280, 200–216 (2011)

56 Griffin, W. L., Powell, W. J., Pearson, N. J. & O’Reilly, S. Y. in Laser Ablation-ICP-MS in the Earth Sciences: Current Practices and Outstanding Issues Vol. 40 (ed. Sylvester, P. J. ) 308–311 (Mineralogical Association of Canada, 2008)

57 Ludwig, K. R. User’s Manual for Isoplot 3.70. Berkeley Geochronology Center Special Publication 76 (2008)

58 Reed, W. P. Certificate of Analysis, Standard Reference Materials 612 and 613. Tech. Rep., U. S. National Institute of Standards & Technology (1992)