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Diamond xenolith and matrix organic matter in the Sutter's Mill meteorite measured by C‐ XANES
Author(s) -
Kebukawa Yoko,
Zolensky Michael E.,
Kilcoyne A. L. David,
Rahman Zia,
Jenniskens Peter,
Cody George D.
Publication year - 2014
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12312
Subject(s) - xanes , meteorite , diamond , chondrite , geology , mineralogy , analytical chemistry (journal) , materials science , chemistry , spectroscopy , astrobiology , metallurgy , physics , chromatography , quantum mechanics
The Sutter's Mill ( SM ) meteorite fell in El Dorado County, California, on April 22, 2012. This meteorite is a regolith breccia composed of CM chondrite material and at least one xenolithic phase: oldhamite. The meteorite studied here, SM 2 (subsample 5), was one of three meteorites collected before it rained extensively on the debris site, thus preserving the original asteroid regolith mineralogy. Two relatively large (10 μm sized) possible diamond grains were observed in SM 2‐5 surrounded by fine‐grained matrix. In the present work, we analyzed a focused ion beam ( FIB ) milled thin section that transected a region containing these two potential diamond grains as well as the surrounding fine‐grained matrix employing carbon and nitrogen X‐ray absorption near‐edge structure (C‐ XANES and N‐ XANES ) spectroscopy using a scanning transmission X‐ray microscope ( STXM ) (Beamline 5.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory). The STXM analysis revealed that the matrix of SM 2‐5 contains C‐rich grains, possibly organic nanoglobules. A single carbonate grain was also detected. The C‐ XANES spectrum of the matrix is similar to that of insoluble organic matter ( IOM ) found in other CM chondrites. However, no significant nitrogen‐bearing functional groups were observed with N‐ XANES . One of the possible diamond grains contains a Ca‐bearing inclusion that is not carbonate. C‐ XANES features of the diamond‐edges suggest that the diamond might have formed by the CVD process, or in a high‐temperature and ‐pressure environment in the interior of a much larger parent body.