Xuchao Zhao¹, Yangting Lin¹, Qing-Zhu Yin², Jianchao Zhang¹, Jialong Hao¹, Michael Zolensky³ and Peter Jenniskens^4,5

¹Key Laboratory of the Earth’s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
²Department of Earth and Planetary Sciences, University of California at Davis, Davis, California, USA
³ARES, NASA Johnson Space Center, Houston, Texas, USA
⁴SETI Institute, Mountain View, California, USA
⁵NASA Ames Research Center, Moffett Field, California, USA

The Sutter’s Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter’s Mill sections, SM43, SM51, SM2-4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C-anomalous grains and one O-anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C-anomalous grains and 2 ppm for presolar oxides. Thirty-one silicon carbide (SiC), five carbonaceous grains, and one Al-oxide (Al₂O₃) were confirmed based on their elemental compositions determined by C-N-Si and O-Si-Mg-Al isotopic measurements. The overall abundance of SiC grains in Sutter’s Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter’s Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2-4 shows heterogeneous distributions of presolar SiC grains (12–54 ppm) in different matrix areas, indicating that the fine-grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.

Reference
Zhao X, Lin Y, Yin Q-Z, Zhang J, Hao J, Zolensky M and Jenniskens P (in press) Presolar grains in the CM2 chondrite Sutter’s Mill. Meteoritics & Planetary Science
[doi:10.1111/maps.12289]
Published by arrangement with John Wiley & Sons

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