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Fe‐redox changes in Itokawa space‐weathered rims

DOI: 10.1111/maps.13611 DOI Help

Authors: L. J. Hicks (University of Leicester) , J. C. Bridges (University of Leicester) , T. Noguchi (Kyushu University) , A. Miyake (Kyoto University) , J. D. Piercy (University of Leicester) , S. H. Baker (University of Leicester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Meteoritics & Planetary Science , VOL 312

State: Published (Approved)
Published: January 2021
Diamond Proposal Number(s): 19641 , 23232 , 26303

Open Access Open Access

Abstract: 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.

Diamond Keywords: Asteroids

Subject Areas: Earth Science, Chemistry

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E01-JEM ARM 200CF , E02-JEM ARM 300CF , I14-Hard X-ray Nanoprobe , I18-Microfocus Spectroscopy

Added On: 25/01/2021 13:48


Discipline Tags:

Earth Sciences & Environment Geology Mineralogy Chemistry Geochemistry Planetary Geology

Technical Tags:

Imaging Microscopy Spectroscopy X-ray Fluorescence (XRF) Electron Microscopy (EM) X-ray Absorption Spectroscopy (XAS) Transmission Electron Microscopy (TEM)