Nitrogen Isotopic Composition and Density of the Archean Atmosphere

Bernard Marty (1) , Laurent Zimmermann (1) , Magali Pujol (1) , Ray Burgess (2) , Pascal Philippot (3)

1 CRPG - Centre de Recherches Pétrographiques et Géochimiques
2 University of Manchester [Manchester]
3 IPGP - Institut de Physique du Globe de Paris

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.

Domaines: Géochimie

Bernard Marty, Laurent Zimmermann, Magali Pujol, Ray Burgess, Pascal Philippot. Nitrogen Isotopic Composition and Density of the Archean Atmosphere. Science, 2013, ⟨10.1126/science.1240971⟩. ⟨hal-01346331⟩