Calcium‐aluminum‐rich inclusions in enstatite chondrites (II): Oxygen isotopes
Calcium‐aluminum‐rich inclusions in enstatite chondrites (II): Oxygen isotopes
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顽辉石球粒陨石中富含钙铝的包裹体（II）：氧同位素
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
K. Keil
中科院分区：
文献类型：
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作者：
T. Fagan;K. McKeegan;A. Krot;K. Keil
摘要-3型EH球粒陨石中耐火富钙铝包裹体（CAIs）中尖晶石的原位离子探针分析得出富含16 O的成分（δ 18 O和δ 17 O约-40 ‰）。来自EL 3球粒陨石的CAI中的尖晶石和长石具有明显较重的同位素组成（δ 18 O和δ 17 O约为−5‰）。通过数据回归，在三同位素图上得到斜率为1.0的线，类似于碳质方解石中CAIs中未蚀变矿物的同位素结果。在碳质和顽火辉石中存在富16 O和贫16 O的CAIs，表明CAIs形成于至少两个时间或空间上不同的氧气储层中。顽火辉石，碳质和普通方解石的CAIs的氧同位素组成的一般相似性表明一个共同的星云机制或现场生产的大多数CAIs。
Abstract— In situ ion microprobe analyses of spinel in refractory calcium‐aluminium‐rich inclusions (CAIs) from type 3 EH chondrites yield 16O‐rich compositions (δ 18O and δ 17O about‐40‰). Spinel and feldspar in a CAI from an EL3 chondrite have significantly heavier isotopic compositions (δ 18O and δ 17O about −5‰). A regression through the data results in a line with slope 1.0 on a three‐isotope plot, similar to isotopic results from unaltered minerals in CAIs from carbonaceous chondrites. The existence of CAIs with 16O‐rich and 16O‐poor compositions in carbonaceous as well as enstatite chondrites indicates that CAIs formed in at least two temporally or spatially distinct oxygen reservoirs. General similarities in oxygen isotopic compositions of CAIs from enstatite, carbonaceous, and ordinary chondrites indicate a common nebular mechanism or locale for the production of most CAIs.