Deciphering the behaviour of chalcophile and siderophile elements during planetary differentiation

解读行星分化过程中亲铜元素和亲铁元素的行为

• 批准号: RGPIN-2016-05304
• 负责人: Brenan, James
• 金额: $ 2.91万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615614
• 关键词: Deciphering; behaviour; chalcophile; siderophile; elements

The highly siderophile, or iron-loving, elements (HSE) include the more familiar precious metals (platinum, palladium, rhodium and gold) as well as exotic varieties (rhenium, osmium, ruthenium and iridium). They are all useful to society, owing to exceptional thermal, surface and electronic properties. The HSE are also of value to geologists, as they are unique in their tendency to avoid oxygen, and bond to iron, sulfur, as well as other “sulfur-like” elements, such as arsenic. The HSE are therefore sensitive to how planets separate into a metallic core, mantle and crust. My research program has involved laboratory simulation of these processes, with a specific focus on determining how the HSE get concentrated above normal background levels; be it by iron metal, other minerals, or unusual iron-sulfur (sulfide) melts. The planned research will continue work to understand the efficiency of HSE extraction from magma by sulfide melt, and also investigate the role of arsenic, an element normally scarce in the earth, but concentrated when magmas digest sedimentary rock. Research will also move into a poorly known area, and that is the role of highly pressurized water, containing dissolved solvents, at transporting the HSE, as well as the related sulfur-loving (or chalcophile) elements. Knowledge of the scavenging capacity of sulfide melts makes it easier to inventory the HSE content of other planets from measurements of their surface lavas, whose sulfide has remained at depth. This is particularly important for understanding the origin of the moon, for which interior samples are unavailable, as paradoxically, the HSE levels in lunar lavas seems to be too low if it experienced the same formation history as the earth. In some ore deposits, arsenic minerals containing high concentrations of the more valuable HSE (Pt, Rh) are found, so determining how and when they form will help to evaluate arsenic as a “primary collector” of the precious metals. Information on the role of pressurized water in dissolving the HSE and “sulfur-like” elements is used to determine the extent to which fluids produced when the ocean floor is downthrust beneath adjoining tectonic plates carry these elements upwards, into the zone of melting that gives rise to volcanoes and mineral deposits. The composition of the residual, dewatered material can then be predicted as well, which provides insight into the longterm compositional changes of the deep earth, as well as the origin of unusual element concentrations brought back to the surface when this material is melted at depth. In sum, this work seeks to provide the essential information for using the HSE and related elements to understand how planets form and evolve. Information gained from this research is also of value to the exploration and mining industry, as it provides insight into how the mechanisms by which these elements may be concentrated to economic levels.

高度铁的或爱铁的元素（HSE）包括更熟悉的贵金属（铂，钯，阳极铬和黄金）以及异国情调（Rhenium，Osmium，osmium，ruthenium和Iridium）。由于出色的热，表面和电子特性，它们都对社会有用。 HSE对地质学家也很有价值，因为它们在避免氧气以及与铁，硫以及其他“硫样”元素（例如砷）的趋势上是独一无二的。因此，HSE对行星如何分离成金属芯，地幔和地壳很敏感。我的研究计划涉及对这些过程的实验室仿真，特别着眼于确定HSE如何集中到正常背景水平；无论是通过铁金属，其他矿物质还是不寻常的铁硫（硫化物）融化。计划的研究将继续努力，以了解硫化物融化从岩浆中提取HSE的效率，并研究砷的作用，砷是通常在地球中稀缺的元素，但在岩浆消化沉积岩石时会集中。研究还将进入一个鲜为人知的区域，这是含有溶解溶液的高度加压水的作用，在运输HSE以及相关的热爱硫（或鸡脂）元素方面的作用。了解硫化物融化能力的清除能力使从其表面熔岩的测量中库存其他行星的HSE含量变得更加容易，其硫化物的深度保持深入。这对于理解月球的起源尤其重要，因为矛盾的是，如果它经历了与地球相同的地层历史，则矛盾的是，月球熔岩中的HSE水平似乎太低了。在某些矿床中，发现含有高浓度的更有价值的HSE（PT，RH）的砷矿物质，因此确定它们的形成方式和何时形成将有助于评估砷作为贵金属的“主要收集器”。有关加压水在溶解HSE和“硫样”元件中的作用的信息用于确定当海底在毗邻的构造板下方下方呈现液体时产生的液体的程度，将这些元素向上移动，进入融化的区域，进入火山和矿物质的融化区域。然后也可以预测残留，脱水的材料的组成，从而深入了解深层深地球的长期组成变化，以及当该材料在深度融化时，不寻常的元素浓度的起源带回了表面。总而言之，这项工作旨在提供使用HSE和相关元素来了解行星形成和进化的基本信息。从这项研究中获得的信息也对勘探和采矿业具有价值，因为它可以洞悉这些要素如何集中在经济水平上的机制。