TY - JOUR
T1 - Assessment of alteration processes on circumstellar and interstellar grains in Queen Alexandra Range 97416
AU - Bose, Maitrayee
AU - Zega, Thomas J.
AU - Williams, Peter
N1 - Funding Information:
The authors thank the three anonymous reviewers who greatly improved the manuscript. MB would like to thank the Meteorite Working group for providing a thin-section of QUE 97416, Klaus Franzreb for help with maintenance of the NanoSIMS, James Anderson for SEM access, and Michelle Thompson for help with figures. MB and PW would like to thank NSFs Major Research Instrumentation (NSF ARRA award # 0960334 ) and ASU for acquisition and installation of the NanoSIMS 50L. TZ's effort was supported in part by the NASA Cosmochemistry Program (grant # NNX12AK47G ). The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 .
PY - 2014/8/1
Y1 - 2014/8/1
N2 - Insight into the presolar and interstellar grain inventory of the CO3 chondrite Queen Alexandra Range (QUE) 97416 is gained through correlated secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), and synchrotron-based X-ray absorption near-edge structure spectroscopy (XANES). Only one presolar silicate grain [O17/O16=(9.96±0.75)×10-4; O18/O16=(19.49±0.96)×10-4] that may have formed in a low-mass Red Giant or Asymptotic Giant Branch star occurs in the coarse-grained matrix of QUE 97416. No other presolar grains were identified. Although presolar grains are rare in QUE 97416, numerous (898 ± 259 ppm) 15N-rich domains (δN15~+1447‰ to +3069‰) occur in the thin section. Based on TEM of an extracted section, two 15N-rich domains are amorphous, C-bearing, and texturally uniform, and they are embedded in a ferromagnesian silicate matrix with varied grain sizes. The individual 15N-rich organic regions with high δN15 (+2942 ± 107‰ and +2341 ± 140‰) exhibit diverse carbon functional groups, such as aromatic, vinyl-keto, amidyl, and carboxylic functionality, while the nitrogen XANES reveals traces of nitrile functionality. QUE 97416 appears to have escaped aqueous alteration based on the absence of hydrated minerals but is thermally altered, which could have resulted in the destruction of presolar grains. However, this process at >400°C metamorphic temperatures was inefficient in destroying the carriers of N isotope anomalies, which may indicate the resistant nature of the organic carriers and/or the limited extent of thermal metamorphism on the QUE 97416 parent body.
AB - Insight into the presolar and interstellar grain inventory of the CO3 chondrite Queen Alexandra Range (QUE) 97416 is gained through correlated secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), and synchrotron-based X-ray absorption near-edge structure spectroscopy (XANES). Only one presolar silicate grain [O17/O16=(9.96±0.75)×10-4; O18/O16=(19.49±0.96)×10-4] that may have formed in a low-mass Red Giant or Asymptotic Giant Branch star occurs in the coarse-grained matrix of QUE 97416. No other presolar grains were identified. Although presolar grains are rare in QUE 97416, numerous (898 ± 259 ppm) 15N-rich domains (δN15~+1447‰ to +3069‰) occur in the thin section. Based on TEM of an extracted section, two 15N-rich domains are amorphous, C-bearing, and texturally uniform, and they are embedded in a ferromagnesian silicate matrix with varied grain sizes. The individual 15N-rich organic regions with high δN15 (+2942 ± 107‰ and +2341 ± 140‰) exhibit diverse carbon functional groups, such as aromatic, vinyl-keto, amidyl, and carboxylic functionality, while the nitrogen XANES reveals traces of nitrile functionality. QUE 97416 appears to have escaped aqueous alteration based on the absence of hydrated minerals but is thermally altered, which could have resulted in the destruction of presolar grains. However, this process at >400°C metamorphic temperatures was inefficient in destroying the carriers of N isotope anomalies, which may indicate the resistant nature of the organic carriers and/or the limited extent of thermal metamorphism on the QUE 97416 parent body.
KW - CO3 chondrite
KW - NanoSIMS
KW - Organic matter
KW - QUE 97416
KW - TEM
KW - XANES
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U2 - 10.1016/j.epsl.2014.05.007
DO - 10.1016/j.epsl.2014.05.007
M3 - Article
AN - SCOPUS:84901660273
SN - 0012-821X
VL - 399
SP - 128
EP - 138
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -