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Chains of magnetite crystals in the meteorite ALH84001: Evidence of biological origin

AuthorsImre Friedman, E.; Wierzchos, Jacek ; Ascaso, Carmen ; Winklhofer, Michael
KeywordsMagnetite crystals
meteorite ALH84001
Biological origin
Issue Date27-Feb-2001
CitationPnas 98(5): 2176-2181 (2001)
AbstractThe 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.
Description6 pages, figures, and tables statistics.
Publisher version (URL)http://dx.doi.org/10.1073/pnas.051514698
Appears in Collections:(IRN) Artículos
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