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Magnetic tests for magnetosome chains in Martian meteorite ALH84001

Weiss, Benjamin P. and Kim, Soon Sam and Kirschvink, Joseph L. and Kopp, Robert E. and Sankaran, Mohan and Kobayashi, Atsuko and Komeili, Arash (2004) Magnetic tests for magnetosome chains in Martian meteorite ALH84001. Proceedings of the National Academy of Sciences of the United States of America, 101 (22). pp. 8281-8284. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:WEIpnas04

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Abstract

Transmission electron microscopy studies have been used to argue that magnetite crystals in carbonate from Martian meteorite ALH84001 have a composition and morphology indistinguishable from that of magnetotactic bacteria. It has even been claimed from scanning electron microscopy imaging that some ALH84001 magnetite crystals are aligned in chains. Alignment of magnetosomes in chains is perhaps the most distinctive of the six crystallographic properties thought to be collectively unique to magnetofossils. Here we use three rock magnetic techniques, low-temperature cycling, the Moskowitz test, and ferromagnetic resonance, to sense the bulk composition and crystallography of millions of ALH84001 magnetite crystals. The magnetic data demonstrate that although the magnetite is unusually pure and fine-grained in a manner similar to terrestrial magnetofossils, most or all of the crystals are not arranged in chains.


Item Type:Article
Additional Information:Copyright © 2004 by the National Academy of Sciences. Communicated by Norman H. Sleep, Stanford University, Stanford, CA, March 31, 2004 (received for review August 7, 2003). Published online before print May 20, 2004, 10.1073/pnas.0402292101 We thank T. Bosak for helpful advice and N. H. Sleep for communicating this manuscript. S.S.K. and the ferromagnetic resonance measurements were supported by the Mars Instrument Development Project Program; R.E.K. was supported by a National Science Foundation Graduate Research Fellowship; A. Komeili was supported by a Beckman Senior Research Fellowship; and B.P.W. and J.L.K. were supported by the National Aeronautics and Space Administration Exobiology Program and the National Aeronautics and Space Administration Astrobiology Institute.
Subject Keywords:biogenic magnetite, verwey transition, crystals, Mars, magnetofossils, carbonates, origin, life
Record Number:CaltechAUTHORS:WEIpnas04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:WEIpnas04
Alternative URL:http://dx.doi.org/10.1073/pnas.0402292101
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1135
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:22 Dec 2005
Last Modified:14 Nov 2014 19:18

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