The samarium-146 ( 146 Sm)–neodymium-142 ( 142 Nd) short-lived decay system (half-life of 103 million years) is a powerful tracer of the early mantle-crust evolution of planetary bodies. However, an increased 142 Nd/ 144 Nd in modern terrestrial rocks relative to chondrite meteorites has been proposed to be caused by nucleosynthetic anomalies, obscuring early Earth’s differentiation history. We use stepwise dissolution of primitive chondrites to quantify nucleosynthetic contributions on the composition of chondrites. After correction for nucleosynthetic anomalies, Earth and the silicate parts of differentiated planetesimals contain resolved excesses of 142 Nd relative to chondrites. We conclude that only collisional erosion of primordial crusts can explain such compositions. This process associated with planetary accretion must have produced substantial loss of incompatible elements, including long-term heat-producing elements such as uranium, thorium, and potassium.

中文翻译：

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地球的组成因碰撞侵蚀而改变

钐146 (146Sm)--钕-142 (142Nd) 短寿命衰变系统（半衰期为 1.03 亿年）是行星体早期地壳演化的有力示踪剂。然而，增加了142钕/144与球粒陨石相比，现代陆地岩石中的 Nd 被认为是由核合成异常引起的，从而掩盖了地球早期的分化历史。我们使用原始球粒陨石的逐步溶解来量化核合成对球粒陨石组成的贡献。在对核合成异常进行校正后，地球和分化的小行星的硅酸盐部分含有已解决的过量142Nd 相对于球粒陨石。我们得出结论，只有原始地壳的碰撞侵蚀才能解释这种成分。这个与行星吸积相关的过程必然导致不相容元素的大量损失，包括铀、钍和钾等长期产热元素。