Widespread 54Cr Heterogeneity in the Inner Solar System
Widespread 54Cr Heterogeneity in the Inner Solar System
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DOI：
10.1086/510360
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发表时间：
2007-02
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影响因子：
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通讯作者：
A. Trinquier;J. Birck;C. Allègre
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文献类型：
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作者：
A. Trinquier;J. Birck;C. Allègre
短寿命放射性核素可以用作高分辨率计时器，用于确定行星形成的时间尺度，条件是它们均匀地分布在吸积盘中。然而，在陨石中观察到的同位素异常证明了早期太阳系中的不完全混合。高精度热电离质谱（TIMS）现在可以确定富含中子的同位素54Cr中的同位素异常，其异常小至百万分之12。在这里，我们报告系统赤字54铬相对于地球的分化熔融星子（母体的eucrites，diogenites，mesosidites，pallasites，angrites，和火星），甚至在一些南极洲的材料（普通南极洲）。结合变量54铬过剩的碳质方解石，这意味着至少有两个星云水库共存的分化和critical机构。保存的54铬在空间和时间（几百万年）的不均匀性促使我们推测，后期恒星输入（S）可能是显着的贡献内星云铬水库或54铬宇宙记忆保存完好的载体的矿物学。由此产生的空间，动力学和时间的影响，太阳系的形成和定年模型进一步探讨。
Short-lived radionuclides can be used as high-resolution chronometers for establishing timescales of planetary formation provided that they were homogeneously distributed in the accretion disk. However, isotopic anomalies observed in meteorites bear evidence of incomplete mixing in the early solar system. High-precision thermal ionization mass spectrometry (TIMS) now enables the determination of isotopic anomalies as small as 12 parts per million in the neutron-rich isotope 54Cr. Here, we report systematic deficits in 54Cr relative to Earth in differentiated molten planetesimals (the parent bodies of eucrites, diogenites, mesosiderites, pallasites, angrites, and Mars) and even in some chondritic material (ordinary chondrites). In combination with variable 54Cr excesses in the carbonaceous chondrites, this implies that at least two nebular reservoirs coexisted for differentiated and chondritic bodies. Preservation of the 54Cr heterogeneity in space and time (several million years) motivates us to speculate that late stellar input(s) could have been significant contributions to inner nebula Cr reservoirs or that the 54Cr cosmic memory was well preserved by the mineralogy of the carriers. The consequent spatial, dynamical, and temporal implications regarding solar system formation and dating models are explored further.