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Iron isotope biosignaturesThe (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.
Document ID
20040141826
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Beard, B. L.
(University of Wisconsin-Madison, USA. Laboratory 1215 West Dayton Street, Madison, WI 53706, MS 183-301, 4800 Oak Grove Road, Pasadena, CA 91109-8009, United States)
Johnson, C. M.
Cox, L.
Sun, H.
Nealson, K. H.
Aguilar, C.
Date Acquired
August 22, 2013
Publication Date
September 17, 1999
Publication Information
Publication: Science
Volume: 285
Issue: 5435
ISSN: 0036-8075
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center JPL
NASA Discipline Exobiology

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