Department of Mineral Sciences,American Museum of Natural History/Department of Mineral Sciences,American Museum of Natural History/Enrico Fermi Institute,University of Chicago/Enrico Fermi Institute,University of Chicago/Department of Mineralogy,The Natural History Museum/Planetary Sciences Unit, Department of Earth Sciences, The Open University
抄録(英)
The (1) CR chondrites, (2) LEW 85332,(3) Acfer 182,(4) ALH 85085-like chondrites, and (5) Bencubbin-like chondritic breccias are five kinds of chondritic groups which have dramatically different petrographic characteristics, but have mineralogical, bulk chemical, and oxygen and nitrogen isotopic similarities that indicate they are closely related. They are all considered to be members of what we term the CR chondrite clan. Distinguishing characteristics of CR clan chondrites include : (a) reduced, Mg-rich mafic silicates, (b) hydrous matrix and/or dark inclusions (except for Bencubbin-like chondrites), (c) high modal abundances of FeNi metal, (d) FeNi metal having a solar Ni : Co ratio, (e) solar (CI) abundances of refractory and moderately volatile lithophiles, and highly depleted abundances of volatile lithophiles, (f) similar oxygen isotopic compositions of whole rocks, chondrules and matrices, which are on or near the CR mixing line, and (g) anomalously high ^<15>N abundances. CR clan chondrites must have formed in the same local region of the nebula, from closely related reservoirs of materials. The coexistence of anhydrous chondrules with hydrous matrix (and dark inclusions) in the LEW 85332,Acfer 182,and ALH 85085-like chondrites, as well as the widely differing degrees of hydration within and between chondritic samples, implies that hydration of the components was not variable in a single locality, but took place at a variety of locales prior to final lithification of the CR clan chondrites.
雑誌書誌ID
AA10784627
雑誌名
Proceedings of the NIPR Symposium on Antarctic Meteorites
The CR chondrite clan
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KJ00000036472
(2.69MB)
概要
