The origin of volatiles in the mantle

地幔挥发物的起源

基本信息

批准号：
NE/D004292/1
负责人：
Christopher Ballentine
金额：
$ 47.75万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FD004292%2F1
关键词：
origin volatiles mantle

项目摘要

Evidence about the early history of the Earth and how it formed has been almost completely destroyed by tectonic activity. However, volcanic gases from the Earth's mantle still preserve a relict of this information. This proposal identifies a key set of samples where we can make new observations that will constrain how the Earth got its volatiles and how the early atmosphere formed: Gases in the Earth's mantle are a mixture of gases trapped when the Earth formed, and gases recycled from the atmosphere into the mantle by subduction as the Earth has evolved. Noble gas isotopes are chemically unreactive and have different isotopic fingerprints depending on whether they come from the atmosphere, meteorites, or even the solar nebula. Identifying these fingerprints gives us unique information about the origin of volatiles in the Earth. These fingerprints are also distorted by different processes that could occur in the early earth. For example more soluble gases such as Helium would be concentrated in the melt if there was equilibrium between a molten Earth and an early atmosphere. In contrast, light gases, driven by meteorite bombardment, would be the first to be lost from the atmosphere. To be able to unravel these early processes we first need to identify what supplies the early Earth with its volatiles. We then need to compare the distortion of the different fingerprints with that predicted for different models of atmosphere/mantle interaction and evolution. For example, the noble gas isotopes now in the atmosphere are often explained by massive early atmosphere loss buffered by degassing from the planet. This would produce a predictable distortion of the gases trapped in the Earth's mantle. But what do we actually see? The main gases that could address these issues (Ar, Kr and Xe) have been, until now, impossible to resolve from the atmospheric fingerprint caused by seawater recycling into the mantle and contamination of samples on eruption. Volcanic carbon dioxide 'well-gases', for the first time allow us to see the 'primitive' Xe isotope fingerprint. If Xe primitive Xe is present, we have shown in this proposal that we should also be able to resolve primitive Ar and Kr / but only with the latest technology. We calculate that with a new instrument we can not only resolve primitive Xe, but also start to identify the type of material that carried it to the Earth. By resolving associated Ar and Kr we can start to identify the distortion and which accretionary processes was the cause. In addition, some noble gas isotopes are also formed by radioactive decay and these give us information about the timing of some of these early processes. Combining this information we can build a unique picture of from what, how and when the volatiles both in the deep Earth and present day atmosphere got there.

有关地球早期历史及其形成方式的证据几乎完全被构造活动摧毁了。然而，来自地幔的火山气体仍然保留着这些信息的遗迹。该提案确定了一组关键样本，我们可以在这些样本中进行新的观察，这些样本将限制地球如何获得挥发物以及早期大气如何形成：地幔中的气体是地球形成时捕获的气体和从地幔中回收的气体的混合物。随着地球的演化，大气层通过俯冲进入地幔。稀有气体同位素不发生化学反应，并且根据它们是否来自大气、陨石甚至太阳星云而具有不同的同位素指纹。识别这些指纹为我们提供了有关地球挥发物起源的独特信息。这些指纹也被早期地球可能发生的不同过程所扭曲。例如，如果熔融地球和早期大气之间存在平衡，则更易溶解的气体（例如氦气）将浓缩在熔体中。相比之下，由陨石轰击驱动的轻气体将首先从大气中消失。为了能够解开这些早期过程，我们首先需要确定早期地球的挥发物是由什么提供的。然后，我们需要将不同指纹的失真与不同大气/地幔相互作用和演化模型的预测进行比较。例如，现在大气中的惰性气体同位素通常可以用行星脱气缓冲的大量早期大气损失来解释。这将使地幔中的气体产生可预测的扭曲。但我们实际上看到了什么？迄今为止，无法从海水循环进入地幔和喷发时样本污染所造成的大气指纹中解析出可以解决这些问题的主要气体（Ar、Kr 和 Xe）。火山二氧化碳“井气”首次让我们看到了“原始”Xe 同位素指纹。如果 Xe 原语 Xe 存在，我们在本提案中表明，我们也应该能够解析原语 Ar 和 Kr /，但只能使用最新的技术。我们计算出，使用新仪器，我们不仅可以解析原始Xe，还可以开始识别将其携带到地球的材料类型。通过解析相关的 Ar 和 Kr，我们可以开始识别扭曲以及哪些吸积过程是原因。此外，一些惰性气体同位素也是由放射性衰变形成的，这些同位素为我们提供了有关其中一些早期过程的时间的信息。结合这些信息，我们可以构建一幅独特的图片，了解地球深处和当今大气中的挥发物是从什么地方、如何以及何时到达那里的。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Discovery of underground argon with low level of radioactive 39Ar and possible applications to WIMP dark matter detectors

发现低水平放射性 39Ar 的地下氩及其在 WIMP 暗物质探测器中的可能应用

DOI：
http://dx.10.1016/j.nima.2007.12.032
发表时间：
2008
期刊：
Accelerators, Spectrometers, Detectors and Associated Equipment
影响因子：
0
作者：
Acosta
通讯作者：
Acosta

The noble gas geochemistry of natural CO2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA

美国科罗拉多高原和落基山省天然二氧化碳气藏的稀有气体地球化学

DOI：
10.1016/j.gca.2007.10.009
发表时间：
2008-02-15
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
S. Gilfillan;C. Ballentine;G. Holl;D. Blagburn;B. S. Lollar;S. Stevens;M. Schoell;M. Cassidy
通讯作者：
M. Cassidy

A multiple-system study of the geochemical evolution of the mantle with force-balanced plates and thermochemical effects

利用力平衡板块和热化学效应研究地幔地球化学演化的多系统研究

DOI：
10.1016/j.epsl.2008.08.027
发表时间：
2008-11-30
期刊：
Earth and Planetary Science Letters
影响因子：
5.3
作者：
J. P. Br;enburg;enburg;E. Hauri;P. V. Keken;C. Ballentine
通讯作者：
C. Ballentine

What CO2 well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere.

二氧化碳井气体告诉我们地幔中稀有气体的起源及其与大气的关系。

DOI：
http://dx.10.1098/rsta.2008.0150
发表时间：
2008
期刊：
Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
影响因子：
0
作者：
Ballentine CJ
通讯作者：
Ballentine CJ

Meteorite Kr in Earth's mantle suggests a late accretionary source for the atmosphere.

地幔中的陨石 Kr 暗示了大气层的晚期增生源。