Origin of volatile element depletion in the Earth

在此基础上，我们提出将实验研究扩展到研究挥发性元素的蒸发和冷凝行为。在前两个资助阶段，我们专注于早期的星云过程。我们将实验结果应用于球粒形成的场景，并能够解释-至少定性-地球，月球和灶神星的不同Mn/Na比率。在资助的第三个时期，我们建议量化在太阳系历史的最初100万年内发生的蒸发和（再）冷凝过程和通量。我们还将重点讨论地球和月球之间的化学分馏。月球中挥发性元素（Na， K等）含量低是月球形成撞击过程中蒸发过程的结果。这些过程可能会影响W，因为WO3非常易挥发。地球和月球的Hf/W比值相似，说明W没有挥发。这需要实验验证。因此，我们想在实验中加入WO3，以了解WO3的挥发性到底有多高。结果可能会对Hf/W定年产生深远的影响。所有实验将涵盖广泛的条件（温度，氧逸度，总压（小于1bar），硅酸盐熔体成分）。此外，我们计划根据热力学-动力学分析提取相关的物理参数，以便进一步推断。这样我们就能更好地模拟导致月球（以及地球、其他行星和陨石）挥发性元素耗竭的过程。

Based on results of the proposals we propose in this renewal to expand the experimental studies to investigate evaporation and condensation behavior of volatile elements. In the former two periods of funding we concentrated on early nebular processes. We applied the experimental results to scenarios of chondrule formation and were able to explain - at least qualitatively - the different Mn/Na ratios of Earth, Moon, and Vesta. In the third period of funding we propose to quantify the evaporation and (re)condensation processes and fluxes that occurred within the first million years of the history of the solar system. We will also focus on the chemical fractionation between the Earth and Moon. The low contents of volatile elements (Na, K, etc.) in the Moon are the result of evaporation processes during the Moon-forming impact. These processes may have affected W, as WO3 is very volatile. The similarity in Hf/W ratios of Earth and Moon suggests that W was not volatized. This needs experimental verification. We therefore want to include WO3 in our experiments to find out how volatile WO3 really is. The results may have far reaching consequences for Hf/W dating. All experiments will cover a wide range of conditions (temperature, oxygen fugacity, total pressure (less than 1 bar), silicate melt compositions). In addition, we plan to extract relevant physical parameters based on a thermodynamic - kinetic analysis that allows further extrapolations. We will then be better able to model the processes that led to the depletion of volatile elements in the Moon (but also in Earth, other planets, and meteorites).