Well-resolved variations in the formation ages for Ca-Al-rich inclusions in the early Solar System
Well-resolved variations in the formation ages for Ca-Al-rich inclusions in the early Solar System
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早期太阳系中富含 Ca-Al 包裹体的形成年龄的变化已得到很好的解决
DOI：
10.1016/j.epsl.2012.03.010
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发表时间：
2012
影响因子：
5.3
通讯作者：
A. Davis
中科院分区：
文献类型：
--
作者：
G. MacPherson;N. Kita;T. Ushikubo;E. Bullock;A. Davis
最近球粒陨石中富钙铝包裹体（CAIs）的全岩镁同位素数据表明，铝和镁的主要星云分馏（可能是冷凝）发生在距今不到2万年的4.567Ga。然而，Vigarano （CV3）对不同cai的高精度多收集器微探针数据显示，内部等时线在初始26al /27Al中有明显的分布，这意味着cai形成和再处理的时间跨度要长得多。原始（未熔化）cai的恒定值为5.2±0.1×10−5，熔化cai的范围为5.17×10−5至4.24×10−5，具有复杂多阶段历史的单个物体的内部范围为26al /27Al=(4.77−2.77)×10−5。整个范围对应于~0.7Ma的年龄跨度。因此，并不是所有的人工智能都是在“时间零”形成的，只有最原始的人工智能才应该被用作最早太阳系年表的基准。
Recent whole-rock magnesium-isotopic data for calcium-aluminum-rich inclusions (CAIs) in chondrite meteorites indicate that the primary nebular fractionation of aluminum from magnesium, probably by condensation, occurred within <20,000years at 4.567Ga. However, high-precision multicollector ion microprobe data for diverse CAIs from Vigarano (CV3) yield internal isochrons with a clearly resolved spread in initial26Al/27Al, meaning that CAIs formed and were reprocessed over a much longer time span. Primitive (unmelted) CAIs have a consistent value of 5.2±0.1×10−5, melted CAIs range from 5.17×10−5to 4.24×10−5, and one single object with a complex multistage history has an internal range of26Al/27Al=(4.77−2.77)×10−5. The entire range corresponds to an age span of ~0.7Ma. Thus not all CAIs formed at “time zero”, and only the most primitive CAIs should be used as benchmarks for earliest Solar System chronology.