Discovery prospects for a supernova signature of biogenic origin

✍ Scribed by S. Bishop; R. Egli

• Book ID: 103830769
• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 241 KB
• Volume: 212
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1016/j.icarus.2011.02.003

✦ Synopsis

Approximately 2.8 Myr before the present our planet was subjected to the debris of a supernova explosion. The terrestrial proxy for this event was the discovery of live atoms of 60 Fe in a deep-sea ferromanganese crust. The signature for this supernova event should also reside in magnetite (Fe 3 O 4 ) microfossils produced by magnetotactic bacteria extant at the time of the Earth-supernova interaction, provided the bacteria preferentially uptake iron from fine-grained iron oxides and ferric hydroxides. Using estimates for the terrestrial supernova 60 Fe flux, combined with our empirically derived microfossil concentrations in a deep-sea drill core, we deduce a conservative estimate of the 60 Fe fraction as 60 Fe/Fe % 3.6 Â 10 À15 . This value sits comfortably within the sensitivity limit of present accelerator mass spectrometry capabilities. The implication is that a biogenic signature of this cosmic event is detectable in the Earth's fossil record.