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Nitrogen isotope signatures of microfossils suggest aerobic metabolism 3.0 Gyr ago

F. Delarue1,

1Muséum National d'Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France

F. Robert1,

1Muséum National d'Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France

K. Sugitani2,

2Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan

R. Tartèse3,

3School of Earth and Environmental Sciences, University of Manchester, M13 9PL Manchester, UK

R. Duhamel1,

1Muséum National d'Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France

S. Derenne4

4Sorbonne Université, UPMC, CNRS, EPHE, PSL, UMR 7619 METIS, 4 place Jussieu, F-75005 Paris, France

Affiliations  |  Corresponding Author  |  Cite as  |  Funding information

Delarue, F., Robert, F., Sugitani, K., Tartèse, R., Duhamel, R., Derenne, S. (2018) Nitrogen isotope signatures of microfossils suggest aerobic metabolism 3.0 Gyr ago. Geochem. Persp. Let. 7, 32–36.

ERC Grant No. 290861 – PaleoNanoLife (PI F. Robert)

Geochemical Perspectives Letters v7  |  doi: 10.7185/geochemlet.1816
Received 10 July 2017  |  Accepted 10 June 2018  |  Published 24 July 2018
Copyright © The Authors

Published by the European Association of Geochemistry
under Creative Commons License CC BY-NC-ND 4.0




Figure 1 Nitrogen isotopic composition of amorphous carbonaceous matter, and of spheroidal, film-like and lenticular-like microfossils from the 3.0 Ga Farrel Quartzite formation. δ15NBulk values are provided for comparison with δ15Nµm values.
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Figure 2 Cartoon illustrating the sedimentary conditions of the Farrel Quartzite formation. The blue gradient in the water column indicates change in NH4+ concentration from high (dark) to low (light) concentrations in anoxic zones. δ15Nµm values determined at the scale of individual microfossil and organic particle are represented by orange diamonds. In the proposed model, negative δ15Nµm values reflect assimilation of NH4+ from benthic efflux whereas positive δ15Nµm values reflect 15N Rayleigh distillation of NH4+ upward through ammonia oxidation when NH4+ concentrations were too low to allow the isotopic fractionation of ammonia assimilation to be expressed (see main text).
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