利用钒同位素来确定月球形成物质的比例  

Using Vanadium Isotopes to Constrain the Proportion of Lunar-forming Material

作　　者：石震 戚玉菡 黄方[1,3] 丁昕[1] SHI Zhen;QI Yuhan;HUANG Fang;DING Xin(CAS Key Laboratory of Crust-Mantle Materials and Environments,School of Earth and Space Sciences/University of Science and Technology of China,Hefei 230026,China;Earth and Atmospheric Sciences,University of Alberta,Edmonton,Alberta T6G 2E3,Canada;CAS Center for Excellence in Comparative Planetology,Hefei 230026,China)

机构地区：[1]中国科学院壳幔物质与环境重点实验室,中国科学技术大学地球和空间科学学院,合肥230026 [2]阿尔伯塔大学地球与大气科学系,加拿大埃德蒙顿阿尔伯塔T6G 2E3 [3]中国科学院比较行星学卓越创新中心,合肥230026

出　　处：《高校地质学报》2024年第3期371-378,共8页Geological Journal of China Universities

基　　金：国家自然科学基金重点项目(41630206)资助。

摘　　要：经典碰撞模型是目前解释月球形成过程的最广为接受的假说,其要求一个约火星大小的撞击体Theia与吸积最后阶段的原始地球相撞,且月球主要来自撞击体Theia。然而关于撞击体对于月球质量贡献的百分比仍缺乏精确的制约。该研究采用地幔橄榄岩和科马提岩的高精度测量数据,用于重新评估硅酸盐全地球(BSE)的V同位素组成,相比之前的研究,新的数据表明δ^(51)V_(BSE)=-0.91‰±0.02‰(2SE,n=18)。将其重新代入到地月双组分混合模型中,考虑了一个包含撞击前(原地球、Theia)和撞击后(地球、月球、逸出物质)成分的系统,得出现今月球中Theia的质量分数的最佳估计为M_(Theia)=0.8*M_(Mars)时的73%到M_(Theia)=0.45*M_(Earth)时的83%。这与先前的研究相比,降低了对Theia在月球形成中的贡献度约5%。这一结果为经典碰撞模型提供了更可靠的参数,有助于深化对月球形成过程的理解。The classic giant impact model is currently the most widely accepted hypothesis for explaining the lunar formation process.It posits a collision between a proto-Earth in its late accretion stage and a Mars-sized impactor named Theia.According to this model,the majority of the Moon’s material is derived from Theia.However,there is still a lack of precise constraints on the contribution percentage of the impactor to the lunar mass.In this study,high-precision measurements of mantle peridotites and komatiites are employed to reevaluate the V isotope composition of the Bulk Silicate Earth(BSE).Unlike previous studies,the new data indicate δ^(51)V_(BSE)=-0.91±0.02‰(2SE,n=18).We incorporated this into a two-component mixing model for the Earth-Moon system,considering a system with pre-impact(proto-Earth,Theia)and post-impact(Earth,Moon,escaping mass)components.The best estimate for the mass fraction of Theia in the present Moon ranges from 73% for M_(Theia)=0.8M_(Mars) to 83% for M_(Theia)=0.45M_(Earth).This represents a reduction of approximately 5% in Theia’s contribution compared to earlier studies.These findings provide more reliable parameters for the classic collision model,contributing to a deeper understanding of the lunar formation process.

关 键 词：经典碰撞模型 硅酸盐全地球 月球 钒同位素 

分 类 号：P618.61[天文地球—矿床学]