Presentation Information
[PPS12-P07]Analysis of Fe particles and Al-rich particles in Allende meteorite using FIB-TOF-SIMS
*Mamoru Masuda1, Shion Shirai1, Tetsuo Sakamoto1,2 (1.Electrical Engineering and Electronics Program, Graduate School of Engineering, Kogakuin University, 2.Department of Applied Physics, School of Advanced Engineering, Kogakuin University)
Keywords:
Allende meteorite,chondrule,matrix,TOF-SIMS
The matrix of the Allende meteorite (CV3) is known to contain olivine, pyroxene, Fe-Ni sulfides, spinel, Fe-Ni metal, and other components (e.g., K. Kurihara et al., 2023). Many of these occur as fine particles smaller than several micrometers, requiring high-resolution analytical techniques to obtain the composition and distribution of individual grains. The focused ion beam time-of-flight secondary ion mass spectrometry (FIB-TOF-SIMS) instrument developed in our group enables high-resolution mass imaging. Using this technique, we previously identified Al-rich fine particles in the matrix of the Allende meteorite (T. Sakamoto et al., 2022). These particles are sub-micrometer minerals primarily composed of Al, Fe, and Mg. They are found at olivine grain boundaries across nearly all regions of the matrix and are also clustered around Fe-Ni sulfides. In the present study, we performed elemental imaging using FIB-TOF-SIMS on Fe particles within the fine-grained rims of chondrules, as well as on Fe-bearing rims surrounding chondrules. We then compared the elemental distributions around Fe in and around these Fe particles with those around Fe-Ni sulfides in the matrix.
Samples were embedded in indium, and smooth cross-sections were prepared by ion milling (IB-19530CP, JEOL). Two specimens containing the chondrule-matrix boundary were prepared and analyzed. FIB-TOF-SIMS mass imaging was performed by raster-scanning a 30 keV Ga+ primary ion beam over the sample surface. The mass imaging results show that around the Fe-Ni sulfides in the fine-grained rims of the chondrules, Al-rich fine particles are clustered around and exhibit distributions similar to those observed in the matrix. Fine-grained nepheline was observed around the chondrule in one sample, with Na detected in the Fe particles. In the other sample, a Fe-bearing rim was present surrounding the chondrule, and Al-rich fine particles were distributed around this Fe as well. We plan to compare the compositions and distributions of these particles with those around Fe-Ni sulfides in the matrix in detail.
Samples were embedded in indium, and smooth cross-sections were prepared by ion milling (IB-19530CP, JEOL). Two specimens containing the chondrule-matrix boundary were prepared and analyzed. FIB-TOF-SIMS mass imaging was performed by raster-scanning a 30 keV Ga+ primary ion beam over the sample surface. The mass imaging results show that around the Fe-Ni sulfides in the fine-grained rims of the chondrules, Al-rich fine particles are clustered around and exhibit distributions similar to those observed in the matrix. Fine-grained nepheline was observed around the chondrule in one sample, with Na detected in the Fe particles. In the other sample, a Fe-bearing rim was present surrounding the chondrule, and Al-rich fine particles were distributed around this Fe as well. We plan to compare the compositions and distributions of these particles with those around Fe-Ni sulfides in the matrix in detail.