Magnetite in ALH 84001: An origin by shock‐induced thermal decomposition of iron carbonate
Abstract
Abstract— In martian orthopyroxenite ALH 84001, pockets of feldspathic glass frequently contain carbonate masses that have been disrupted and dispersed within feldspathic shock melt as a result of impact(s). Transmission electron microscope studies of carbonate fragments embedded within feldspathic glass show that the fragments contain myriad, nanometer‐sized magnetite particles with cuboid, irregular, and teardrop morphologies, frequently associated with voids. The fragments of carbonate must have been incorporated into the melt at temperatures of ˜900°C, well above the upper thermal stability of siderite (FeCO 3 ), which decomposes to produce magnetite and CO 2 below ˜450°C. These observations suggest that most, if not all, of the fine‐grained magnetite associated with Fe‐bearing carbonate in ALH 84001 could have been formed as result of the thermal decomposition of the siderite (FeCO 3 ) component of the carbonate and is not due to biological activity.
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Brearley (2003) speculated that fracturing of the magnetite rim matrix boundary is evidence of a volume decrease associated with magnetite formation from siderite during a shock event.
“Brearley (2003) speculated that fracturing of the magnetite rim matrix boundary is evidence of a volume decrease associated with magnetite formation from siderite during a shock event.”
From Comprehensive imaging and Raman spectroscopy of carbonate globules from Martian meteorite ALH 84001 and a terrestrial analogue from Svalbard (2007) · cites this paper as Brearley 2003
Brearley (2003) proposed that during this heating event, the meteorite was experiencing considerable thermal heterogeneity.
“Concomitant to the shock event, Brearley (2003) proposed that during this heating event, the meteorite was experiencing considerable thermal heterogeneity, a factor expanded upon by Treiman (2003).”
From Comprehensive imaging and Raman spectroscopy of carbonate globules from Martian meteorite ALH 84001 and a terrestrial analogue from Svalbard (2007) · cites this paper as Brearley 2003
Cites
The Age of the Carbonates in Martian Meteorite ALH84001
Borg, L. E., Connelly, J. N., Nyquist, L. E., Shih, C.-Y., Wiesmann, H., & Reese, Y. (1999) · Science · doi:10.1126/science.286.5437.90 · Cited by 190 · see citing works
Use of the Mössbauer effect to study the thermal decomposition of sidewire
Gallagher, P. K., West, K. W., & Warne, S. S. J. (1981) · Thermochimica Acta · doi:10.1016/0040-6031(81)85041-1 · Cited by 26 · see citing works
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Steele, A., Fries, M. D., Amundsen, H. E. F., Mysen, B. O., Fogel, M. L., Schweizer, M., & Boctor, N. Z. (2007) · Meteoritics & Planetary Science · doi:10.1111/j.1945-5100.2007.tb00590.x · Cited by 117 · see citing works
BELL, M. S. (2007) · Meteoritics & Planetary Science · doi:10.1111/j.1945-5100.2007.tb01142.x · Cited by 53 · see citing works
- Authors
- BREARLEY, A. J.
- Affiliations
- University of New Mexico (US)
- Corresponding author
- BREARLEY, Adrian J.
- ORCID
- BREARLEY, Adrian J.
- Venue
- Meteoritics & Planetary Science
- Publisher
- Wiley
- Published
- 2003-06
- Volume
- 38
- Issue
- 6
- Pages
- 849-870
- ISSN
- 1086-9379 (ISSN-L)
- 1945-5100
- OpenAlex
- W2087959356
- Cited by
- 39
- References
- 2
- Citations by year
- 2026: 1 · 2025: 2 · 2024: 2 · 2023: 2 · 2022: 2 · 2021: 2 · 2020: 1 · 2018: 3 · 2016: 3 · 2014: 2 · 2013: 2 · 2012: 3
- FWCI
- 0.96
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Meteoritics and Planetary Science (publishedVersion)
- UA Campus Repository (The University of Arizona) (acceptedVersion)
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Planetary Science and Exploration
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astro and Planetary Science
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Geomagnetism and Paleomagnetism Studies
- Keywords
- ALH84001, magnetite, siderite, iron carbonate, thermal decomposition, Martian meteorites, orthopyroxenite, carbonates
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