Document Detail

Geochemistry: biosignatures and abiotic constraints on early life.
MedLine Citation:
PMID:  17167427     Owner:  NLM     Status:  MEDLINE    
Ueno et al. contend that methane found in fluid inclusions within hydrothermally precipitated quartz in the Dresser Formation of western Australia (which is roughly 3.5 Gyr old) provides evidence for microbial methanogenesis in the early Archaean era. The authors discount alternative origins for this methane, suggesting that the range of delta(13)C(CH(4)) values that they record (-56 to -36 per thousand) is attributable to mixing between a primary microbial end-member with a delta(13)C(CH(4)) value of less than -56 per thousand and a mature thermogenic gas enriched in (13)C (about -36 per thousand). However, abiotic methane produced experimentally and in other Precambrian greenstone settings has (13)C-depleted delta(13)C(CH(4)) values, as well as Delta(13)C(CO(2)-CH(4)) relationships that encompass the range measured for the inclusions by Ueno et al. - which suggests that an alternative, abiotic origin for the methane is equally plausible. The conclusions of Ueno et al. about the timing of the onset of microbial methanogenesis might not therefore be justified.
Barbara Sherwood Lollar; Thomas M McCollom
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Publication Detail:
Type:  Comment; Journal Article    
Journal Detail:
Title:  Nature     Volume:  444     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-12-14     Completed Date:  2007-01-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  E18; discussion E18-9     Citation Subset:  IM    
Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada.
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MeSH Terms
Carbon Isotopes
Geologic Sediments / chemistry*,  microbiology*
Methane / metabolism*
Quartz / chemistry
Reproducibility of Results
Time Factors
Reg. No./Substance:
0/Carbon Isotopes; 14808-60-7/Quartz; 74-82-8/Methane
Comment On:
Nature. 2006 Mar 23;440(7083):516-9   [PMID:  16554816 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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