Using Vanadium Isotopes to Constrain the Proportion of Lunar-forming Material
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=0.8MMara 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.
国家科技期刊平台
NSTL
万方数据
