Efficient mixing of the solar nebula from uniform Mo isotopic composition of meteorites
Efficient mixing of the solar nebula from uniform Mo isotopic composition of meteorites
复制标题
DOI：
10.1038/nature01975
复制
发表时间：
2003-09
期刊：
影响因子：
64.8
通讯作者：
H. Becker;R. Walker
中科院分区：
文献类型：
--
作者：
H. Becker;R. Walker
我们银河系中元素及其同位素的丰度变化很大，反映了恒星中不同的核合成过程和银河系演化的影响。这些变化与太阳系中许多元素稳定同位素丰度的均匀性形成对比，这意味着在年轻的太阳星云中，来自不同恒星来源的尘埃和气体的过程有效地均匀化。然而，在亚厘米尺度上发现了原始陨石的同位素不均匀性，这表明这些陨石保留了它们恒星来源的成分记忆。相对于地球上的Mo，一些原始和分化的陨石中大块岩石中稳定钼同位素丰度的微小差异表明，在一些太阳系内部天体之间存在大规模的Mo同位素不均匀性，这意味着物理条件不允许气体和尘埃的有效混合。在这里，我们报告了原始和分化陨石的大量样品的Mo同位素数据，显示与地球Mo没有可分辨的偏差。这表明太阳星云中气体和尘埃的有效混合至少距离太阳30英里，可能是由磁流体动力学不稳定性引起的。这些混合过程一定发生在气相元素的同位素分馏和挥发性控制的化学分馏建立之前。
The abundances of elements and their isotopes in our Galaxy show wide variations, reflecting different nucleosynthetic processes in stars and the effects of Galactic evolution. These variations contrast with the uniformity of stable isotope abundances for many elements in the Solar System,, which implies that processes efficiently homogenized dust and gas from different stellar sources within the young solar nebula. However, isotopic heterogeneity has been recognized on the subcentimetre scale in primitive meteorites,, indicating that these preserve a compositional memory of their stellar sources. Small differences in the abundance of stable molybdenum isotopes in bulk rocks of some primitive,,and differentiated,meteorites, relative to terrestrial Mo, suggest large-scale Mo isotopic heterogeneity between some inner Solar System bodies, which implies physical conditions that did not permit efficient mixing of gas and dust. Here we report Mo isotopic data for bulk samples of primitive and differentiated meteorites that show no resolvable deviations from terrestrial Mo. This suggests efficient mixing of gas and dust in the solar nebula at least to 3aufrom the Sun, possibly induced by magnetohydrodynamic instabilities. These mixing processes must have occurred before isotopic fractionation of gas-phase elements and volatility-controlled chemical fractionations were established.