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Experimental investigation into the thermodynamic properties of halogens

卤素热力学性质的实验研究

基本信息

批准号：
1941721
负责人：
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：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1941721
关键词：
Experimental investigation into thermodynamic properties

项目摘要

Recent research has shown that the Earth accreted and differentiated over 30-40 Myr,ecoming more oxidised through time. Stable continental crust was then established relatively quickly. These processes led to the segregation of siderophile (iron-loving) elements to the Earths core and incompatible lithophile (rock-loving) elements to the crust. One of the most intriguing questions facing planetary science is whether the processes experienced by the growing Earth represent those which took place on other terrestrial planets or even exoplanets. The answer lies with Earths nearest neighbour: Mars.The Mars Exploration Rovers (MER) and orbital missions continue to deliver largevolumes of high-quality chemical and mineralogical data from the Martian surface, including bountiful measurements of halogens, including chlorine and bromine. In addition,the Mars Odyssey Gamma Ray Spectrometer (GRS) has mapped the equatorial and midlatitude distribution of elemental Cl abundances at the near-surface of Mars (Zhao and McLennan, 2012). These datasets show the upper few tens of centimetres of Mars is significantly enriched in Cl relative to Martian meteorites and estimates for the bulk composition of the planet. However, it is not homogenously distributed.Much of the focus on the Cl-rich mineralogy of Mars derives from studies of the nakhlite and chassignite meteorites, each containing a broad array of magmatic volatile bearing minerals including Cl-enrichment (Filiberto and Treiman 2009; Filberto, et al., 2014). According to McCubbin et al., (2009), there is a clear link between chlorine-rich hydrothermal uids and magmatic activity in Chassigny and MIL 03346, but it is presently unclear whether the Cl-rich uid was exogenous or endogenous to the magmatic system. M'dard and Grove (2008), found that on a molar basis, Cl is twice as effective as H2O in depressing the liquidus of basalts. Although this does suggest that the addition of Cl to the Martian mantle may lower the magma genesis temperature and potentially aid in the petrogenesis of Martian magmas, current experiments have only explored a basalt composition with a xed Cl concentration; hence, applying their results to the range of Cl concentrations in terrestrial and Martian magmas becomes problematic. Other experiments evaluate the intrinsic effects of dissolved chlorine on Fe3+/PFe and magnetite solubility in hydrous chloride-rich rhyodacitic liquids, and show Cl addition to the melt has two prominent effects on iron: (1) dissolved Cl perturbs the magnetite-melt equilibrium, such that greater FeO total contents are required to support magnetite saturation in Cl-bearing melts than in Cl-free melts of equivalent bulk compositions; and (2) a systematic and progressive decrease of the measured Fe3+/PFe as fO2 is increased. Hence, the two intimately related effects each have important implications for redox processes occurring in Cl-enriched arc magmas. It is, however, well established that the Martian planet is vastly more Fe-rich than rhyodacitic melts. Therefore, bulk composition with lower Al2O3 and higher FeO contents should be tested to further constrain its effect on the influence of chlorine on near-liquidus crystallisation.The solubility of Cl has only been investigated for felsic magmas as above, with few experiments on Martian magmas compositions, which differ significantly from terrestrial. Therefore, the effect of Martian enriched FeO magmas on the solubility of halogens such as Cl is poorly understood. As it is unknown what in infuences Cl solubility, deciphering the partitioning behaviours of the martian mantle will be key to understanding the magmatic activity on Mars.I therefore propose to study Cl solubility within the Martian mantle through experimental methodology, creating chemically similar compositions to assess, if, and the extent at which Fe influences solubility, as this will shed light on the Martia magmatism and evolution.

最近的研究表明，地球在30-40百万年的时间里增生和分化，随着时间的推移变得更加氧化。稳定的大陆地壳很快就形成了。这些过程导致亲铁（爱铁）元素分离到地球的核心和不相容的亲石（爱岩石）元素到地壳。行星科学面临的最有趣的问题之一是，地球成长所经历的过程是否代表了其他类地行星甚至系外行星所经历的过程。答案就在地球最近的邻居--火星上。火星探测漫游者（MER）和轨道任务继续从火星表面提供大量高质量的化学和矿物学数据，包括对卤素（包括氯和溴）的邦蒂富尔测量。此外，火星奥德赛伽马射线分光仪绘制了火星近地表氯元素丰度的赤道和中纬度分布图（Zhao和McLennan，2012年）。这些数据集显示，相对于火星陨石，火星上部几十厘米处的Cl含量显著富集，并估计了火星的整体组成。然而，它并不是均匀分布的。对火星富氯矿物学的关注主要来自对赤霞岩和赤霞珠陨石的研究，每种陨石都含有一系列广泛的岩浆挥发性矿物，包括Cl富集（Filiberto和Treiman，2009年; Filberto等人，2014年）。根据McCubbin等人的研究，（2009），在Chassigny和MIL 03346中，富氯热液流体与岩浆活动之间存在明显的联系，但目前尚不清楚富氯流体对于岩浆系统是外源的还是内源的。M 'dard和格罗夫（2008年）发现，以摩尔计，Cl在降低玄武岩液相线方面的效果是H2O的两倍。虽然这确实表明，除了Cl的火星地幔可能会降低岩浆的成因温度和潜在的援助，在火星岩浆的岩石成因，目前的实验只探索了玄武岩的组合物与固定的Cl浓度，因此，应用他们的结果的范围内的Cl浓度在陆地和火星岩浆成为问题。其他实验评价了溶解氯对富氯流纹英质液体中Fe ~（3+）/PFe和磁铁矿溶解度的内在影响，并表明Cl对铁有两个显著的影响：（1）溶解Cl扰乱磁铁矿-熔体平衡，使得含Cl熔体中支持磁铁矿饱和所需的FeO总量比相同体相组成的无Cl熔体中所需的要大;（2）随着fO 2的增加，测得的Fe ~（3+）/PFe呈系统的、渐进的下降趋势。因此，这两个密切相关的影响，每一个都有重要的意义发生在Cl-富集弧岩浆的氧化还原过程。然而，已经确定的是，火星行星比流纹英安质熔体更富含铁。因此，大量的组成与较低的Al 2 O3和较高的FeO含量，应进行测试，以进一步限制其影响氯的影响近液相线crystallisation.The溶解度的Cl只进行了研究长英质岩浆如上，与火星岩浆的组成，这与地球显着不同的实验。因此，人们对火星富FeO岩浆对Cl等卤素溶解度的影响知之甚少。由于它是未知的infuences氯溶解度，破译火星地幔的分配行为将是关键，了解火星上的岩浆activity.I因此，建议通过实验方法研究火星地幔内的Cl溶解度，创建化学相似的组合物，以评估，如果，以及在何种程度上Fe影响溶解度，因为这将揭示火星岩浆活动和演化。