1M. Kimura, 1N. Imae, 2M. Komatsu, 1A. Yamaguchi
Meteoritics & Planetary Science (in Press)
Open Access Link to Article [DOI: 10.1111/maps.70248]
1National Institute of Polar Research, Tokyo, Japan
2Division of Liberal Arts and Sciences, Saitama Prefectural University, Saitama, Japan
Published by arrangement with John Wiley & Sons
Carbonaceous chondrites commonly contain amoeboid olivine aggregates (AOAs).Here, we investigated an AOA in the CR chondrite Y-793261. This AOA contains anunstable assemblage of forsterite and quartz. We found a rare occurrence of enstatite andquantitatively discuss its formation process. This enstatite occurs specifically betweenforsterite and quartz, indicating a solid-state reaction between them. By applying theexperimental results of Imae et al. (Proc. Japan Aca. 75: 229–234), we determined that thisAOA formed under high-temperature conditions (≳1169 K) over a period of approximately1–5 years. The reservoir where the AOA formed was enriched in 16 O. Subsequently, it cooledrapidly and was transported to the reservoir where the parent body accreted, incorporatingchondrules and matrix. The thermal history and physicochemical conditions of this AOA areapplicable to other AOAs.
