Carbon XANES library of the heat-treated and impacted IOM simulant applied to the extraterrestrial organic matter
Abstract
Hayabusa2 mission aimed at conducting sample return from a C-type asteroid named Ryugu, which is considered to be the parent body of the carbonaceous chondrite. As for the formation process of the Ryugu, a various hypotheses have been considered. Analytical approaches using returned samples are expected to provide direct information on them. Here, we are preparing to build the X-ray Absorption Near Edge Structure around carbon K-edge (C-XANES) library for heat-treated and impacted insoluble organic matter (IOM), simulating the experienced temperature and pressure of Ryugu. As for the analog of the extraterrestrial organic matter, the shock experienced samples of organic simulants of planetary bodies (OSPBs) which recovered from shock wave with 0, 2, 5, 10, and 12 GPa, described in Sekine et al. (2018), was prepared. First, C-XANES of the bulk OSPBs were measured to obtain the alteration trend of shocked OSPBs. Then, carbon chemical states in OSPB particles were tried to be investigated at sub-micron scale by scanning transmission X-ray microscope (STXM).
Bulk and STXM C-XANES measurements showed that the original functional group's peaks in the C-XANES decrease with increasing of the experience pressure, which may result in starting of carbonization and graphitization. The C-XANES feature of shock-recovered OSPBs above about 7 GPa and 400 °C, which would be achieved in a typical asteroid belt collision, showed that the aromatic and graphite peaks are dominant with broad shape. From these results, we can summarize that (i) the aromatic and graphite peaks were not remarkable in the unheated sample, (ii) the aromatic and graphite peaks becomes clear at 8 GPa. It is indicated that carbon chemical states investigation by STXM based on the C-XANES library will provide indispensable information on consideration of the Ryugu alteration scenario. This library is also useful for elucidating the evolution of meteorites with carbonaceous lithology in ordinary chondrites as well as other carbonaceous chondrites which experienced moderate heating induced by asteroidal collision.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP042.0002S
- Keywords:
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- 1039 Alteration and weathering processes;
- GEOCHEMISTRY;
- 5220 Hydrothermal systems and weathering on other planets;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 5419 Hydrology and fluvial processes;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5455 Origin and evolution;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS