Investigation of iron sulfide impact crater residues: A combined analysis by scanning and transmission electron microscopy

Wozniakiewicz, Penelope J., Ishii, Hope A., Kearsley, Anton T., Burchell, Mark J., Bland, Philip A., Bradley, John P., Dai, Zurong, Teslick, Nick, Collins, Gareth S., Cole, Mike J., and others. (2011) Investigation of iron sulfide impact crater residues: A combined analysis by scanning and transmission electron microscopy. Meteoritics & Planetary Science, 46 (7). pp. 1007-1024. ISSN 1086-9379. (doi:10.1111/j.1945-5100.2011.01206.x) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1111/j.1945-5100.2011.01206.x

Abstract

Samples returned from comet 81P/Wild 2 by the Stardust mission provided an unequaled opportunity to compare previously available extraterrestrial samples against those from a known comet. Iron sulfides are a major constituent of cometary grains commonly identified within cometary interplanetary dust particles (IDPs) and Wild 2 samples. Chemical analyses indicate Wild 2 sulfides are fundamentally different from those in IDPs. However, as Wild 2 dust was collected via impact into capture media at approximately 6.1 km s?1, it is unclear whether this is due to variation in preaccretional/parent body processes experienced by these materials or due to heating and alteration during collection. We investigated alteration in pyrrhotite and pentlandite impacted into Stardust flight spare Al foils under encounter conditions by comparing scanning and transmission electron microscope (SEM, TEM) analyses of preimpact and postimpact samples and calculating estimates of various impact parameters. SEM is the primary method of analysis during initial in situ examination of Stardust foils, and therefore, we also sought to evaluate the data obtained by SEM using insights provided by TEM. We find iron sulfides experience heating, melting, separation, and loss of S, and mixing with molten Al. These results are consistent with estimated peak pressures and temperatures experienced (approximately 85 GPa, approximately 2600 K) and relative melting temperatures. Unambiguous identification of preserved iron sulfides may be possible by TEM through the location of Al-free regions. In most cases, the Ni:Fe ratio is preserved in both SEM and TEM analyses and may therefore also be used to predict original chemistry and estimate mineralogy.

Item Type: Article
DOI/Identification number: 10.1111/j.1945-5100.2011.01206.x
Subjects: Q Science > QB Astronomy
Q Science > QD Chemistry
Q Science > QE Geology > QE515 Geochemistry
Divisions: Faculties > Sciences > School of Physical Sciences
Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Mark Burchell
Date Deposited: 05 Dec 2013 13:15 UTC
Last Modified: 29 May 2019 11:34 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/37215 (The current URI for this page, for reference purposes)
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