Abstract：
:Two terrestrial environments that have been proposed as analogs for the iron oxide precipitation in the Meridiani Planum region of Mars include the Rio Tinto precipitates and southern Utah marble concretions. Samples of two typical Utah iron oxide concretions and iron oxide precipitates in contact with biofilms from Rio Tinto have been studied to determine whether evidence could be found for biomediation in the precipitation process and to identify likely locations for fossil microorganisms. Scanning electron microscopy, energy dispersive X-ray, and gas chromatography-mass spectrometry (GC-MS) were used to search for biosignatures in the Utah marbles. The precipitation of iron oxides resembles known biosignatures, though organic compounds could not be confirmed with GC-MS analysis. In contrast, textural variations induced by biological activity are abundant in the modern Rio Tinto samples. Although no compelling evidence of direct or indirect biomediation was found in the Utah marbles, the ultrastructure of the iron oxide cement in the concretion suggests an inward growth during concretion precipitation from an initially spherical redox front. No indication for growth from a physical nucleus was found.
journal_name
Astrobiologyjournal_title
Astrobiologyauthors
Souza-Egipsy V,Ormö J,Beitler Bowen B,Chan MA,Komatsu Gdoi
10.1089/ast.2006.6.527subject
Has Abstractpub_date
2006-08-01 00:00:00pages
527-45issue
4eissn
1531-1074issn
1557-8070journal_volume
6pub_type
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