Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK.
Science. 2023 Jan 27;379(6630):369-372. doi: 10.1126/science.abn1021. Epub 2023 Jan 26.
Material inherited from different nucleosynthesis sources imparts distinct isotopic signatures to meteorites and terrestrial planets. These nucleosynthetic isotope anomalies have been used to constrain the origins of material that formed Earth. However, anomalies have only been identified for elements with high condensation temperatures, leaving the origin of Earth's volatile elements unconstrained. We determined the isotope composition of the moderately volatile element zinc in 18 bulk meteorites and identified nucleosynthetic zinc isotope anomalies. Using a mass-balance model, we find that carbonaceous bodies, which likely formed beyond the orbit of Jupiter, delivered about half of Earth's zinc inventory. Combined with previous constraints obtained from studies of other elements, these results indicate that ~10% of Earth's mass was provided by carbonaceous material.
不同核合成源继承的物质赋予陨石和类地行星独特的同位素特征。这些核合成同位素异常已被用于约束形成地球的物质的起源。然而，只有冷凝温度较高的元素的异常得到了识别，这使得地球挥发性元素的起源没有得到约束。我们测定了 18 个大块陨石中中等挥发性元素锌的同位素组成，并确定了核合成锌同位素异常。利用质量平衡模型，我们发现，很可能在木星轨道之外形成的碳质天体，提供了地球锌储量的约一半。结合以前从其他元素研究中获得的约束条件，这些结果表明，约 10%的地球质量来自碳质物质。
