Chains of magnetite crystals in the meteorite ALH84001: Evidence of biological origin
AUTOR(ES)
Friedmann, E. Imre
FONTE
The National Academy of Sciences
RESUMO
The presence of magnetite crystal chains, considered missing evidence for the biological origin of magnetite in ALH84001 [Thomas-Keprta, K. L., Bazylinski, D. A., Kirschvink, J. L., Clemett, S. J., McKay, D. S., Wentworth, S. J., Vali, H., Gibson, E. K., Jr., & Romanek, C. S. (2000) Geochim. Cosmochim. Acta 64, 4049–4081], is demonstrated by high-power stereo backscattered scanning electron microscopy. Five characteristics of such chains (uniform crystal size and shape within chains, gaps between crystals, orientation of elongated crystals along the chain axis, flexibility of chains, and a halo that is a possible remnant of a membrane around chains), observed or inferred to be present in magnetotactic bacteria but incompatible with a nonbiological origin, are shown to be present. Although it is unlikely that magnetotactic bacteria were ever alive in ALH84001, decomposed remains of such organisms could have been deposited in cracks in the rock while it was still on the surface on Mars.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=30112Documentos Relacionados
- Truncated hexa-octahedral magnetite crystals in ALH84001: Presumptive biosignatures
- Magnetic tests for magnetosome chains in Martian meteorite ALH84001
- Origin of supposedly biogenic magnetite in the Martian meteorite Allan Hills 84001
- Magnetofossils from Ancient Mars: a Robust Biosignature in the Martian Meteorite ALH84001
- Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite