Iron Isotope Biosignatures

摘要

The 56~Fe/54~Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (δ56~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 (δ56~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 δ56~Fe of ferrous Fe in solution is isotopically lighter Than the ferrihydrite substrate by 1.3 per mil.