Noble Gas Partitioning Into The Earth's Outer Core? Ab Initio Calculations On Noble Gas Partitioning Between Silicate and Liquid Iron

惰性气体进入地球外核？

基本信息

批准号：
NE/S01134X/1
负责人：
Lidunka Vocadlo
金额：
$ 56.2万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FS01134X%2F1
关键词：
Noble Gas Partitioning Into Earth

项目摘要

Rocks from some oceanic islands, such as Iceland and Hawaii, show an unusual geochemical signature with the ratio of isotopes of helium (3He/4He) being very high. Because 3He cannot be produced from radioactive decay, all the 3He must have originated from the accreting solar system. This suggests that the source of these rocks comes from material within a deep isolated primordial reservoir that has been trapped within the Earth throughout its history and has not been affected by subsequent mantle mixing and dynamics. For many years, scientists have been "searching" for these primordial reservoirs and have come up with a number of potential locations, such as regions close to the core-mantle boundary (Large Low Shear Velocity Provinces - LLSVPs, and Ultra Low Velocity Zones - ULVZs) and even isolated zones higher up in the mantle (Bridgmanite Enriched Ancient Mantle Structures - BEAMS). But all these suggestions have their problems. However, one deep reservoir that has received relatively little attention is the Earth's liquid outer core. To establish whether the outer core could, indeed, host noble gases, such as helium, requires knowledge of the partitioning of noble gases between the silicate mantle and the liquid iron alloy outer core. In this proposal we will calculate the necessary partition coefficients in order to determine whether or not the sources of primitive noble gases are consistent with an outer core reservoir. Our results will directly influence our understanding of the origin, scale and survival of mantle heterogeneities, and the intrinsic link to mantle convection and core- mantle exchange. These are some of the biggest issues for understanding the evolution of the Earth from its accretion to present day.

冰岛和夏威夷等海洋岛上的岩石显示出不寻常的地球化学特征，其氦同位素（3HE/4HE）的比例很高。由于无法通过放射性衰减产生3E，因此所有3HE都必须源自积分太阳系。这表明这些岩石的来源来自深层孤立的原始水库中的物质，该储层在地球整个历史中都被困在地球内，并未受到随后的地幔混合和动态的影响。 For many years, scientists have been "searching" for these primordial reservoirs and have come up with a number of potential locations, such as regions close to the core-mantle boundary (Large Low Shear Velocity Provinces - LLSVPs, and Ultra Low Velocity Zones - ULVZs) and even isolated zones higher up in the mantle (Bridgmanite Enriched Ancient Mantle Structures - BEAMS).但是所有这些建议都有他们的问题。但是，地球的液体外核是一个相对较少关注的深层水库。为了确定外部芯是否确实可以容纳诸如氦气之类的贵重气体，需要了解硅酸盐地幔与液态铁合金外芯之间的贵重气体分配。在此提案中，我们将计算必要的分区系数，以确定原始贵重气体的来源是否与外核储层一致。我们的结果将直接影响我们对地幔异质性的起源，规模和生存的理解，以及与地幔对流和核心交换的内在联系。这些是了解地球从积聚到当今的发展的最大问题。