Isotope Fractionations during volatile loss from Planets and Asteroids

行星和小行星挥发性损失过程中的同位素分馏

• 批准号: 2099965
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2099965
• 关键词: Isotope; Fractionations; during; volatile; loss

The rocky bodies in the inner Solar System are known to be depleted in moderately volatile elements compared to CI chondritic meteorites, the main building blocks of the planets and moons. The volatile content of these bodies was governed by the mixing of volatile rich CI chondritic material and a volatile-poor material. Recent work by Norris and Wood (2017) has shown that volatile element abundances in the silicate Earth correlate well with the volatility of those elements in a siliceous system, suggesting that the Earth's volatile element budget may be explained by vaporization and devolatilization during early Earth forming events. This challenges the conventional hypothesis that these element depletions can be explained by incorporation of these elements in the core. If volatility is the main cause of element depletions, we should be able to observe this process by looking at isotope fractionation. Our aim for this project is to test the devolatilization hypothesis by investigating the effects of devolatilization on the isotopic composition of several elements. We will look at elements with varying degrees of volatility and depletion in the silicate Earth compared to CI chondritic material, starting with Zn and Cd and progressing to Cu and Pb. We will focus on these as variations in isotopic composition for these elements are known for the Earth, Mars, Vesta and various meteorite classes.We will test our hypothesis in the lab by performing relatively short (60 minute) experiments in a furnace at high temperature, in a heavily reducing environment at atmospheric pressure on rock powders that have been doped with trace elements. The samples are doped in the studied elements to ensure we are able to measure them accurately after the experiments. The resulting run products will be analysed for both elemental and isotopic abundances. By comparing the results from the experiments with available data for the Earth, Moon, Mars and meteorites we will be able to test the initially proposed model of devolatilization and further advance models describing the early evolution of the Earth's volatile budget. This project is a part of the Science and Technology Facilities Council (STFC)'s Astronomy and Space Science Research, specifically focused within Science Challenge B: 'How do stars and planetary systems develop and is life unique to our planet?'. This project will be performed under the supervision of Professor B.J. (Bernard) Wood and Dr. J. (Jane) Barling from the Department of Earth Sciences at the University of Oxford.[1] Norris, C.A., Wood, B.J. (2007). Earth's volatile contents established by melting and vaporization. Nature, vol. 549, p. 507-510

与行星和卫星的主要组成部分 CI 球粒陨石相比，内太阳系的岩石天体中的挥发性元素含量较低。这些物体的挥发物含量由富含挥发物的CI球粒状材料和挥发物贫乏的材料的混合来控制。 Norris 和 Wood (2017) 最近的工作表明，硅酸盐地球中的挥发性元素丰度与硅质系统中这些元素的挥发性密切相关，这表明地球的挥发性元素预算可能是通过早期地球形成事件期间的蒸发和脱挥发分来解释的。这挑战了传统的假设，即这些元素的消耗可以通过这些元素并入核心来解释。如果挥发性是元素消耗的主要原因，我们应该能够通过观察同位素分馏来观察这个过程。我们该项目的目的是通过研究脱挥发分对几种元素同位素组成的影响来检验脱挥发分假说。我们将研究与 CI 球粒陨石材料相比，硅酸盐地球中具有不同程度的挥发性和损耗的元素，从 Zn 和 Cd 开始，逐渐到 Cu 和 Pb。我们将重点关注这些元素，因为地球、火星、灶神星和各种陨石类别中这些元素的同位素组成存在差异。我们将在实验室中通过在高温炉中、在大气压力下的严重还原环境中对掺杂有微量元素的岩石粉末进行相对较短（60 分钟）的实验来检验我们的假设。样品中掺杂了所研究的元素，以确保我们能够在实验后准确测量它们。将分析所得运行产品的元素和同位素丰度。通过将实验结果与地球、月球、火星和陨石的现有数据进行比较，我们将能够测试最初提出的挥发分模型，并进一步改进描述地球挥发预算早期演化的模型。该项目是科学技术设施委员会 (STFC) 天文学和空间科学研究的一部分，特别关注科学挑战 B：“恒星和行星系统如何发展？生命是我们星球所独有的吗？”。该项目将在牛津大学地球科学系的 B.J. (Bernard) Wood 教授和 J. (Jane) Barling 博士的监督下进行。[1]诺里斯，C.A.，伍德，B.J. (2007)。地球通过熔化和汽化而形成的挥发物含量。自然，卷。 549，p。 507-510