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Magnetite in comet Wild 2: evidence for parent body aqueous alteration
Authors:
Leon
Hicks
(University of Leicester)
,
J. L.
Macarthur
(University of Leicester)
,
J. C.
Bridges
(University of Leicester)
,
M. C.
Price
(University of Kent)
,
J. E.
Wickham-Eade
(University of Kent)
,
M. J.
Burchell
(University of Kent)
,
G. M.
Hansford
(University of Leicester)
,
A. L.
Butterworth
(University of California at Berkeley)
,
S. J.
Gurman
(University of Leicester)
,
S. H.
Baker
(University of Leicester)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Meteoritics & Planetary Science
, VOL 53
State:
Published (Approved)
Published:
July 2017
Diamond Proposal Number(s):
1833
,
7487
,
9418
,
10328
,
13690

Abstract: The mineralogy of comet 81P/Wild 2 particles, collected in aerogel by the Stardust mission, has been determined using synchrotron Fe-K X-ray absorption spectroscopy with in situ transmission XRD and X-ray fluorescence, plus complementary microRaman analyses. Our investigation focuses on the terminal grains of eight Stardust tracks: C2112,4,170,0,0; C2045,2,176,0,0; C2045,3,177,0,0; C2045,4,178,0,0; C2065,4,187,0,0; C2098,4,188,0,0; C2119,4,189,0,0; and C2119,5,190,0,0. Three terminal grains have been identified as near pure magnetite Fe3O4. The presence of magnetite shows affinities between the Wild 2 mineral assemblage and carbonaceous chondrites, and probably resulted from hydrothermal alteration of the coexisting FeNi and ferromagnesian silicates in the cometary parent body. In order to further explore this hypothesis, powdered material from a CR2 meteorite (NWA 10256) was shot into the aerogel at 6.1 km s−1, using a light-gas gun, and keystones were then prepared in the same way as the Stardust keystones. Using similar analysis techniques to the eight Stardust tracks, a CR2 magnetite terminal grain establishes the likelihood of preserving magnetite during capture in silica aerogel.
Diamond Keywords: Comets
Subject Areas:
Earth Science
Instruments:
I18-Microfocus Spectroscopy
Added On:
10/07/2017 13:18
Documents:
Hicks_et_al-2017-Meteoritics_&_Planetary_Science.pdf
Discipline Tags:
Earth Sciences & Environment
Mineralogy
Geology
Planetary Geology
Technical Tags:
Diffraction
Imaging
Spectroscopy
X-ray Fluorescence (XRF)
X-ray Absorption Spectroscopy (XAS)
Extended X-ray Absorption Fine Structure (EXAFS)
X-ray Absorption Near Edge Structure (XANES)