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高校地质学报 ›› 2024, Vol. 30 ›› Issue (03): 371-378.DOI: 10.16108/j.issn1006-7493.2023065

• 青年地质学家专辑(Ⅰ) • 上一篇    

利用钒同位素来确定月球形成物质的比例

石 震1,戚玉菡1, 2,黄 方1, 3,丁 昕1*   

  1. 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
  • 出版日期:2024-07-03 发布日期:2024-07-03

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

SHI Zhen1,QI Yuhan1,2,HUANG Fang1,3,DING Xin1*   

  1. 1. 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;
    2. Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada;
    3. CAS Center for Excellence in Comparative Planetology, Hefei 230026, China
  • Online:2024-07-03 Published:2024-07-03

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δ51VBSE=-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MTheia=0.8*MMars时的73%到MTheia=0.45*MEarth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。

关键词: 经典碰撞模型, 硅酸盐全地球, 月球, 钒同位素

Abstract: 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 δ51VBSE=-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 MTheia=0.8MMars to 83% for MTheia=0.45MEarth 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.

Key words: classical collision model, bulk silicate Earth, Moon, vanadium isotopes

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