近日，英国伦敦帝国理工学院Rayssa Martins及其团队探明，陨石中锌的核合成同位素异常限制了地球挥发物的来源。这一研究成果发表在2023年1月27日出版的国际学术期刊《科学》上。

课题组测定了18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。课题组人员使用质量平衡模型，研究发现碳原子体可能形成于木星轨道之外，提供了地球上大约一半的锌库存。结合之前从其他元素研究中获得的限制条件，研究结果表明，大约地球质量的10%是由碳元素物质提供的。

据悉，从不同核合成来源的遗传物质赋予陨石和类地行星不同的同位素特征。这些核合成同位素异常的主题是限制形成地球的物质的起源。然而，只有凝结温度高的元素才会出现异常，这使得地球挥发性元素的起源不受限制了。

附：英文原文

Title: Nucleosynthetic isotope anomalies of zinc in meteorites constrain the origin of Earth’s volatiles

Author: Rayssa Martins, Sven Kuthning, Barry J. Coles, Katharina Kreissig, Mark Rehkmper

Issue&Volume: 2023-01-27

Abstract: 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.

DOI: abn1021

Source: https://www.science.org/doi/10.1126/science.abn1021