Martins Rayssa, Morton Elin M, Kuthning Sven, Goes Saskia, Williams Helen M, Rehkämper Mark
Department of Earth Science & Engineering, Imperial College London, London, UK.
Department of Earth Sciences, University of Cambridge, Cambridge, UK.
Sci Adv. 2024 Oct 11;10(41):eado4121. doi: 10.1126/sciadv.ado4121.
The origins of Earth's volatiles are debated. Recent studies showed that meteorites display unique mass-independent isotopic signatures of the volatile element Zn, suggesting that Earth's Zn originated from materials derived from different regions of the Solar System. However, these studies largely omitted meteorites from the differentiated planetesimals thought to represent the Earth's building blocks, which underwent melting and substantial volatile loss. Here, we characterize the mass-independent Zn isotope compositions of meteorites from such planetesimals. We incorporate these results in mixing models that aim to reproduce Earth's abundance and isotope compositions of Zn and other elements. Our results suggest that, while differentiated planetesimals supplied ~70% of Earth's mass, they provided only ~10% of its Zn. The remaining Zn was supplied by primitive materials that did not experience melting and associated volatile loss. Combined with other findings, our results imply that an unmelted primitive material is likely required to establish the volatile budgets of the terrestrial planets.
地球挥发性物质的起源存在争议。最近的研究表明，陨石显示出挥发性元素锌独特的质量无关同位素特征，这表明地球的锌起源于来自太阳系不同区域的物质。然而，这些研究在很大程度上忽略了来自被认为是构成地球基石的分异小行星的陨石，这些小行星经历了熔化和大量挥发性物质的损失。在这里，我们表征了来自此类小行星的陨石的质量无关锌同位素组成。我们将这些结果纳入混合模型，旨在重现地球锌和其他元素的丰度及同位素组成。我们的结果表明，虽然分异小行星提供了地球约70%的质量，但它们仅提供了地球约10%的锌。其余的锌由未经历熔化和相关挥发性物质损失的原始物质提供。结合其他发现，我们的结果意味着可能需要未熔化的原始物质来确定类地行星的挥发性物质预算。
