Origin of volatile element depletion in the Earth

地球挥发性元素枯竭的根源

• 批准号: 146986262
• 负责人: Professorin Dr. Astrid Holzheid
• 金额: --
• 依托单位: Arbeitsgruppe Experimentelle und Theoretische Petrologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/146986262?language=en
• 关键词: Origin; volatile; element; depletion; Earth

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).

根据这些建议的结果，我们建议在这次更新中扩大实验研究，以调查挥发性元素的蒸发和冷凝行为。在前两个时期的资助，我们集中在早期星云的过程。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-地球，月球和灶神星的不同Mn/Na比。在第三个资助阶段，我们建议量化太阳系历史的第一个百万年内发生的蒸发和（再）冷凝过程和通量。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）含量较低;月球上的尘埃是月球形成撞击期间蒸发过程的结果。这些过程可能影响了W，因为WO 3非常易挥发。地球和月球Hf/W比值的相似性表明W没有挥发。这需要实验验证。因此，我们希望在实验中包括WO 3，以了解WO 3的挥发性。这些结果可能对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（小于1巴）、硅酸盐熔体组成）。此外，我们计划提取相关的物理参数的基础上的热力学动力学分析，允许进一步的外推。这样，我们就能够更好地模拟导致月球（以及地球、其他行星和陨石）挥发性元素耗尽的过程。