The oxygen fugacity of core segregation and the redox evolution of the mantle: constraints from iron and chromium isotopes

核心偏析的氧逸度和地幔的氧化还原演化：来自铁和铬同位素的约束

• 批准号: NE/F014295/2
• 负责人: Helen Williams
• 金额: $ 40.45万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF014295%2F2
• 关键词: oxygen; fugacity; core; segregation; redox

We know very little about the origin of our own planet, how it has evolved through time and how it came to be suitable for life. There is considerable controversy surrounding issues like climate change, and the search for new planets around stars other than the Sun and missions to planets in our own solar system and it is currently a very exciting time to be an Earth scientist. The Earth formed about 4600 million years ago, from particles of dust and rocky material present in the early solar system. Only a few million years later, the Earth underwent a massive reorganisation from an enormous mass of unsorted primitive material into a planet composed of a metal core in its centre and a surrounding rocky outer part. We still do not understand precisely how this happened, as the Earth has undergone a wide range of geological events which hide much of the evidence. One possibility is that when the Earth was still hot and molten, liquid metal separated from the rest of the planet and descended to the centre of the Earth, forming its core. During this process, most of the Earth's iron and many other elements were distributed preferentially into the metal core. This imparted a characteristic chemical signal to the outer rocky parts of the Earth, which we can sample through rocks erupted from volcanoes. However, there are many aspects of this part of Earth history that we do not understand. For example, we do not know the exact conditions of core formation and how it could have affected other aspects of the planet's chemistry, such as the amount of oxygen present in the rocky interior of the planet. This is an important question to answer if we are to understand how life originated on Earth, as it is likely that the Earth's oceans and much of the Earth's atmosphere originated from gases leaking out of planet's interior when the Earth was still very young. My project is aimed at understanding what kind of conditions the Earth's core formed under and how this affected the amount of oxygen present in the rocky interior of the Earth. It uses experiments which simulate the very high pressures and temperatures that would have been present in the Earth's interior when the core formed, combined with very precise chemical analyses of these experiments. From these results I will learn how certain chemical elements distributed themselves between the metal core and the rocky outer part of the Earth, and whether this distribution behaviour changes with different conditions and with the amount of oxygen present. By comparing the results I get from the experiments with the chemical compositions of rocks from the Earth and very primitive meteorites we will be able to understand better how the Earth's core formed, and how this may have affected the chemistry of our planet and the development of its atmosphere and oceans.

我们对自己星球的起源，如何随着时间的流逝以及如何适合生命的来源知之甚少。围绕气候变化等问题以及在我们自己的太阳系中的行星上的恒星和任务上寻找新的星球的问题存在很大争议，目前，成为地球科学家是一个非常激动人心的时刻。地球大约在4.6亿年前，由早期太阳系中存在的灰尘和岩石材料颗粒形成。仅几百万年后，地球从大量未分类的原始物质进行了大规模的重组，进入了一个由中心和周围岩石外部的金属芯组成的行星。我们仍然不确定是如何发生的，因为地球发生了广泛的地质事件，这些事件掩盖了许多证据。一种可能性是，当地球仍然很热熔融时，液态金属与地球的其余部分分离并下降到地球中心，形成其核心。在此过程中，大多数地球的铁和许多其他元素都优先分布到金属芯中。这赋予了地球外岩石部分的特征化学信号，我们可以通过火山爆发的岩石进行采样。但是，地球历史的这一部分有许多方面，我们不了解。例如，我们不知道核心形成的确切条件及其如何影响地球化学的其他方面，例如地球内部岩石内部存在的氧气量。这是一个重要的问题，要回答我们是否要了解生命是如何起源于地球上的，因为地球的海洋和地球大部分大气的大部分可能起源于地球还很年轻时从星球内部泄漏出来的气体。我的项目旨在了解地球核心形成的哪种条件以及这如何影响地球内部岩石内部中存在的氧气量。它使用实验，这些实验模拟了核心形成时地球内部将存在的非常高的压力和温度，并结合了这些实验的非常精确的化学分析。从这些结果中，我将了解某些化学元件如何在金属芯和地球的岩石外部分布，以及这种分布行为是否随不同条件和存在的氧气变化。通过比较我从实验中获得的结果与地球和非常原始的陨石的化学成分，我们将能够更好地理解地球核心的形成方式，以及这可能如何影响地球的化学及其大气和海洋的发展。

项目成果

Silicon isotopes in meteorites and planetary core formation

• DOI: 10.1016/j.gca.2011.03.044
• 发表时间: 2011-07-01
• 期刊: GEOCHIMICA ET COSMOCHIMICA ACTA
• 影响因子: 5
• 作者: Armytage, R. M. G.;Georg, R. B.;Halliday, A. N.
• 通讯作者: Halliday, A. N.

Persistence of deeply sourced iron in the Pacific Ocean.

太平洋中深部铁的持久存在。

• DOI: 10.1073/pnas.1420188112
• 发表时间: 2015
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: Horner TJ

Stable chromium isotopic composition of meteorites and metal-silicate experiments: Implications for fractionation during core formation

• DOI: 10.1016/j.epsl.2015.11.026
• 发表时间: 2016-02-01
• 期刊: EARTH AND PLANETARY SCIENCE LETTERS
• 影响因子: 5.3
• 作者: Bonnand, P.;Williams, H. M.;Halliday, A. N.
• 通讯作者: Halliday, A. N.

Unlocking the zinc isotope systematics of iron meteorites

• DOI: 10.1016/j.epsl.2014.05.029
• 发表时间: 2014-08-15
• 期刊: EARTH AND PLANETARY SCIENCE LETTERS
• 影响因子: 5.3
• 作者: Bridgestock, L. J.;Williams, H.;Schoenbaechler, M.
• 通讯作者: Schoenbaechler, M.

Isotopic evidence for iron mobility during subduction

• DOI: 10.1130/g37565.1
• 发表时间: 2016-03-01
• 期刊: GEOLOGY
• 影响因子: 5.8
• 作者: Debret, B.;Millet, M. -A.;Williams, H.
• 通讯作者: Williams, H.