Understanding the atmosphere's composition during the Archean eon is a fundamental issue to unravel ancient environmental conditions. We show from the analysis of nitrogen and argon isotopes in fluid inclusions trapped in 3.0-3.5 Ga hydrothermal quartz that the PN2 of the Archean atmosphere was lower than 1.1 bar, possibly as low as 0.5 bar, and had a nitrogen isotopic composition comparable to the present-day one. These results imply that dinitrogen did not play a significant role in the thermal budget of the ancient Earth and that the Archean PCO2 was probably lower than 0.7 bar.
@article{arxiv.1405.6337,
title = {Nitrogen Isotopic Composition and Density of the Archean Atmosphere},
author = {Bernard Marty and Laurent Zimmermann and Magali Pujol and Ray Burgess and Pascal Philippot},
journal= {arXiv preprint arXiv:1405.6337},
year = {2014}
}