火星,地球和月球上的超级红状体Sm/Nd比率
Guillaume Caro1, Bernard Bourdon, Alex N Halliday
1Laboratoire Géochimie et Cosmochimie Institut de Physique du Globe de Paris-Université Denis Diderot, 4 place Jussieu, 75252 Paris Cedex 05, France. caro@crpg.cnrs-nancy.fr
Nature
|March 21, 2008
概括
142 (142Nd) 的同位素分析显示,火星和地球一样,具有非合体组成,这表明早期的行星分化. 火星石表明,地幔分化发生在太阳系形成后的4000万年.
科学领域:
- 地质化学 地质化学
- 行星科学 行星科学
- 同位素地球化学 同位素地球化学
背景情况:
- -142 (142Nd) 的同位素变化在酸盐岩石中追踪了通过-146 (146Sm) 衰变的早期行星分化.
- 时间学解释依赖于一种混凝土大质量地球组成的假设,这可能不是真的.
- 陆地样本中的离合体值的偏差表明了早期地幔隔离或非合合体体积组成.
研究的目的:
- 为了研究火星石中新-142 (142Nd) 的同位素组成.
- 为了确定火星是否具有体或非体质量组成.
- 限制早期火星地幔分化的时间和机制.
主要方法:
- 对16颗火星石进行了高精度的142Nd同位素分析.
- 在石数据上应用行星同步技术.
- 火星同位素数据与合体参考值和陆地/月球组成的比较.
主要成果:
- 火星表现出非合体质量组成,其142Nd/144Nd比率证明了这一点.
- 谢尔戈蒂特石石在太阳系形成后的4000万年±1800万年定义了火星地幔差异化等离子.
- 火星的同位素不与体的参考点对齐,表明一个独特的同位素签名.
- 与小行星带材料相比,地球,月球和火星在Sm/Nd比率上表现出类似的丰富.
结论:
- 太阳系内部早期的行星分化和积累过程导致了化学异质.
- 火星在其历史上相对较早地经历了地幔分化.
- 火星和地球之间观察到的同位素相似性 (例如,FOZO成分) 可能源于共享的积累环境或随后的处理.
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