Origin of volatile element depletion in the Earth

根据本次更新中建议的结果，我们建议扩大实验研究，以研究挥发性元素的蒸发和冷凝行为。在前两个资助时期，我们主要关注早期星云过程。我们将实验结果应用到球粒形成的情景中，并能够--至少定性地--解释地球、月球和灶神星的不同的Mn/Na比。在第三期资金中，我们建议对太阳系历史的头一百万年内发生的蒸发和(再)凝结过程和通量进行量化。我们还将关注地球和月球之间的化学分馏。挥发性元素(Na、K等)含量低。是月球形成过程中蒸发过程的结果。这些过程可能影响了钨，因为三氧化二钨非常不稳定。地球和月球的HF/W比值相似，表明W没有挥发。这需要实验验证。因此，我们希望在我们的实验中加入WO_3，以找出WO_3到底有多易挥发。这一结果可能对HF/W测年产生深远的影响。所有实验将涵盖广泛的条件(温度、氧逸度、总压力(不到1巴)、硅酸盐熔体组成)。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，以便进行进一步的推断。然后，我们将能够更好地模拟导致月球(但也包括地球、其他行星和陨石)挥发性元素枯竭的过程。

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).