期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2009
卷号：106
期号：26
页码：10522-10527
DOI：10.1073/pnas.0901546106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition ({delta}15NAIR = -310 {+/-} 20{per thousand}), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material ({delta}15NAIR = 4,900 {+/-} 300{per thousand}). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies.
关键词：isotopic fractionation ; pristine meteorites ; Solar System
