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Fe-redox changes in Itokawa space-weathered rims

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posted on 2021-04-13, 15:34 authored by LJ Hicks, JC Bridges, T Noguchi, A Miyake, JD Piercy, SH Baker
Synchrotron Fe-K X-ray absorption spectroscopy and transmission electron microscopy have been used to investigate the mineralogy and Fe-redox variations in the space-weathered (SW) rims of asteroidal samples. This study focuses on the FIB lift-out sections from five Itokawa grains, returned by the Hayabusa spacecraft, including samples RB-QD04-0063, RB-QD04-0080, RB-CV-0011, RB-CV-0089, and RB-CV-0148. Each of the samples featured partially amorphized SW rims, caused by irradiation damage from implanted low mass solar wind ions, and the impacting of micrometeorites. Using bright-field and HAADF-STEM imaging, vesicular blistering and nanophase Fe metal (npFe0) particles were observed within grain rims, and solar flare tracks were observed in the substrate host grain, confirming the presence of SW zones. We use Fe-K XANES mapping to investigate Fe-redox changes between the host mineral and the SW zones. All SW zones measured show some increases in the ferric-ferrous ratio (Fe3+/ΣFe) relative to their respective host grains, likely the result of the implanted solar wind H+ ions reacting with the segregated ferrous Fe in the surface material.

Funding

Grant‐in‐Aid for Scientific Research

Science and Technology Facilities Council

History

Citation

Meteoritics & Planetary Science 55, Nr 12, 2599–2618 (2020)

Author affiliation

School of Physics and Astronomy

Version

  • VoR (Version of Record)

Published in

Meteoritics & Planetary Science

Volume

55

Issue

12

Pagination

2599 - 2618

Publisher

Wiley Periodicals LLC on behalf of The Meteoritical Society (MET)

issn

1086-9379

eissn

1945-5100

Acceptance date

2020-11-18

Copyright date

2021

Available date

2021-04-13

Language

English

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