Evidence from massive siderite beds for a CO2-rich atmosphere before ~ 1.8 billion years ago

Hiroshi Ohmoto (), Yumiko Watanabe and Kazumasa Kumazawa
Additional contact information
Hiroshi Ohmoto: The Pennsylvania State University
Yumiko Watanabe: The Pennsylvania State University
Kazumasa Kumazawa: Miyazaki Branch, Oshima-cho

Nature, 2004, vol. 429, issue 6990, 395-399

Abstract: Abstract It is generally thought that, in order to compensate for lower solar flux and maintain liquid oceans on the early Earth, methane must have been an important greenhouse gas before ∼2.2 billion years (Gyr) ago1,2,3,4,5. This is based upon a simple thermodynamic calculation that relates the absence of siderite (FeCO3) in some pre-2.2-Gyr palaeosols to atmospheric CO2 concentrations that would have been too low to have provided the necessary greenhouse effect1. Using multi-dimensional thermodynamic analyses and geological evidence, we show here that the absence of siderite in palaeosols does not constrain atmospheric CO2 concentrations. Siderite is absent in many palaeosols (both pre- and post-2.2-Gyr in age) because the O2 concentrations and pH conditions in well-aerated soils have favoured the formation of ferric (Fe3+)-rich minerals, such as goethite, rather than siderite. Siderite, however, has formed throughout geological history in subsurface environments, such as euxinic seas, where anaerobic organisms created H2-rich conditions. The abundance of large, massive siderite-rich beds in pre-1.8-Gyr sedimentary sequences and their carbon isotope ratios indicate that the atmospheric CO2 concentration was more than 100 times greater than today, causing the rain and ocean waters to be more acidic than today. We therefore conclude that CO2 alone (without a significant contribution from methane) could have provided the necessary greenhouse effect to maintain liquid oceans on the early Earth.

Date: 2004
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/nature02573 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:429:y:2004:i:6990:d:10.1038_nature02573

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/nature02573

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().