据研究人员介绍，月球形成于4.5亿年前，是由原始地球和一颗被称为忒伊亚的星子碰撞形成的。地球和月球的成分相似性，严格限制了忒伊亚和原始地球之间的同位素对比，或者它需要忒伊亚和原地球物质在月球形成撞击期间和之后的高度均匀化，或者两者兼而有之。
研究人员对月球和陆地岩石的氧同位素比率进行了精确测量。数据显示，月球和地球在亚ppm水平上不存在同位素差异，地球上地幔和月球不存在同位素非均质性，根据已发表的月球形成情景，和忒伊亚硅酸盐地幔在与原始地球碰撞之前的碰撞侵蚀情景，研究人员对这些进行了讨论。
研究提供的数据为了解地球和月球挥发物的起源提供了有价值的见解，因为它们表明地球上的水可能不是由后期增生输送的。该研究还强调了太空任务带回的样本的科学价值，因为陨石材料可能与地球上的水发生了相互作用。
附：英文原文
Title: Oxygen isotope identity of the Earth and Moon with implications for the formation of the Moon and source of volatiles
Author: Fischer, Meike, Peters, Stefan T. M., Herwartz, Daniel, Hartogh, Paul, Di Rocco, Tommaso, Pack, Andreas
Issue&Volume: 2024-12-16
Abstract: The Moon formed 4.5 Ga ago through a collision between proto-Earth and a planetesimal known as Theia. The compositional similarity of Earth and Moon puts tight limits on the isotopic contrast between Theia and proto-Earth, or it requires intense homogenization of Theia and proto-Earth material during and in the aftermath of the Moon-forming impact, or a combination of both. We conducted precise measurements of oxygen isotope ratios of lunar and terrestrial rocks. The absence of an isotopic difference between the Moon and Earth on the sub-ppm level, as well as the absence of isotope heterogeneity in Earth’s upper mantle and the Moon, is discussed in relation to published Moon formation scenarios and the collisional erosion of Theia’s silicate mantles prior to colliding with proto-Earth. The data provide valuable insights into the origin of volatiles in the Earth and Moon as they suggest that the water on the Earth may not have been delivered by the late veneer. The study also highlights the scientific value of samples returned by space missions, when compared to analyses of meteorite material, which may have interacted with terrestrial water.
DOI: 10.1073/pnas.2321070121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2321070121