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Evolution of atmospheric xenon and other noble gases inferred from Archean to Paleoproterozoic rocks

Avice, G. and Marty, B. and Burgess, R. and Hofmann, A. and Philippot, P. and Zahnle, K. and Zakharov, D. (2018) Evolution of atmospheric xenon and other noble gases inferred from Archean to Paleoproterozoic rocks. Geochimica et Cosmochimica Acta, 232 . pp. 82-100. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20180606-091713113

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Abstract

We have analyzed ancient atmospheric gases trapped in fluid inclusions contained in minerals of Archean (3.3 Ga) to Paleozoic (404 Ma) rocks in an attempt to document the evolution of the elemental composition and isotopic signature of the atmosphere with time. Doing so, we aimed at understanding how physical and chemical processes acted over geological time to shape the modern atmosphere. Modern atmospheric xenon is enriched in heavy isotopes by 30–40‰ u^(−1) relative to Solar or Chondritic xenon. Previous studies demonstrated that, 3.3 Ga ago, atmospheric xenon was isotopically fractionated (enriched in the light isotopes) relative to the modern atmosphere, by 12.9 ± 1.2 (1σ) ‰ u^(−1), whereas krypton was isotopically identical to modern atmospheric Kr. Details about the specific and progressive isotopic fractionation of Xe during the Archean, originally proposed by Pujol et al. (2011), are now well established by this work. Xe isotope fractionation has evolved from 21‰ u^(−1) at 3.5 Ga to 12.9‰ u^(−1) at 3.3 Ga. The current dataset provides some evidence for stabilization of the Xe fractionation between 3.3 and 2.7 Ga. However, further studies will be needed to confirm this observation. After 2.7 Ga, the composition kept evolving and reach the modern-like atmospheric Xe composition at around 2.1 Ga ago. Xenon may be the second atmospheric element, after sulfur, to show a secular isotope evolution during the Archean that ended shortly after the Archean-Proterozoic transition. Fractionation of xenon indicates that xenon escaped from Earth, probably as an ion, and that Xe escape stopped when the atmosphere became oxygen-rich. We speculate that the Xe escape was enabled by a vigorous hydrogen escape on the early anoxic Earth. Organic hazes, scavenging isotopically heavy Xe, could also have played a role in the evolution of atmospheric Xe. For 3.3 Ga-old samples, Ar-N_2 correlations are consistent with a partial pressure of nitrogen (pN_2) in the Archean atmosphere similar to, or lower than, the modern one, thus requiring other processes than a high pN_2 to keep the Earth's surface warm despite a fainter Sun. The nitrogen isotope composition of the atmosphere at 3.3 Ga was already modern-like, attesting to inefficient nitrogen escape to space since that time.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.gca.2018.04.018DOIArticle
ORCID:
AuthorORCID
Avice, G.0000-0003-0962-0049
Additional Information:© 2018 The Authors. Published by Elsevier Ltd. Open Access funded by European Research Council. Under a Creative Commons license. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) Received 15 November 2017, Accepted 16 April 2018, Available online 26 April 2018. This study was funded in Nancy (France) by the European Research Council under the European Community’s Seventh Framework Programme [FP7/2007-2013 grant agreement No. 267255 to B.M.]. Samples from Barberton were recovered thanks to the International Continental Scientific Drilling Program (ICDP). Francis & Isabelle Avice, Elodie Le Mignot, Antonin Richard, Gaston Giuliani and Marie-Christine Boiron are acknowledged for providing samples analyzed in this study. Collection of samples from the Vetreny belt is a Stable Isotope laboratory at University of Oregon effort. Yves Marrocchi is thanked for scientific interactions. Ken Farley is acknowledged for support during preparation of this manuscript. Laurent Zimmermann is gratefully acknowledged for technical mentorship and assistance. Rainer Wieler and an anonymous reviewer are thanked for their constructive comments and suggestions. We thank Nicolas Dauphas for his editorial handling. This is CRPG contribution #2583.
Funders:
Funding AgencyGrant Number
European Research Council (ERC)267255
Subject Keywords:Noble gases; Xenon; Archean; Atmosphere; Escape
Record Number:CaltechAUTHORS:20180606-091713113
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180606-091713113
Official Citation:G. Avice, B. Marty, R. Burgess, A. Hofmann, P. Philippot, K. Zahnle, D. Zakharov, Evolution of atmospheric xenon and other noble gases inferred from Archean to Paleoproterozoic rocks, Geochimica et Cosmochimica Acta, Volume 232, 2018, Pages 82-100, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2018.04.018. (http://www.sciencedirect.com/science/article/pii/S0016703718302151)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86825
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 Jun 2018 16:36
Last Modified:09 Mar 2020 13:18

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