Metal-related mineral assemblages as probes into protoplanetary gas-solid interactions

与金属相关的矿物组合作为原行星气固相互作用的探针

• 批准号: 248746696
• 负责人: Dr. Dennis Harries
• 金额: --
• 依托单位: Institut für Geowissenschaften
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/248746696?language=en
• 关键词: Metal; related; mineral; assemblages; probes

At present, it is largely unknown how water, nitrogen compounds, and other volatile species interacted in the solar protoplanetary disk and, eventually, contributed to the terrestrial oceans and atmosphere. In this project we focus on the reactions of iron-rich metal grains with volatile species during the first ten million years of the Solar System. Due to their high reactivity, metals constitute ideal mineralogical probes into the protoplanetary processes involved. Typical reaction products observed in chondritic meteorites are iron-rich sulfides and oxides, such as pyrrhotite, pentlandite, and magnetite. We aim at deriving decisive criteria in order to differentiate between gas-solid interactions and liquid-water alteration as mechanisms for the origin of such metal-related mineral assemblages, and we aim at elucidating the involved volatile reservoirs. In particular, we will address the unresolved and eminent question whether evaporated multi-component (comet-like) ices played significant roles in protoplanetary gas-solid interactions. This is suggested by novel, nitride-bearing sulfide assemblages, pointing to the former presence of gaseous ammonia.We will test formation hypotheses by a dual approach: (i) By the reconstruction of physicochemical formation conditions from mineralogical and microstructural analysis of metal-related mineral assemblages in chondritic meteorites, (ii) by novel experimental investigation of gas-metal interactions in a low-pressure gas mixing furnace using mixtures of hydrogen, hydrogen sulfide, water, ammonia, and nitrogen. Transmission electron microscopy (TEM) will be a central analytical tool and will be supplemented by secondary ion mass spectrometry (SIMS) for isotopic analysis of oxygen, sulfur, and nitrogen.The results are expected to largely enhance our understanding of the protoplanetary interactions and reservoirs of volatile species. If it can be shown that evaporated multi-component ices were involved, the process and its physicochemical conditions will have important implications for the local redox state of the solar nebula and the evolution of primordial organic species, which were probably contained in such ices and could have been delivered to the early Earth along with other volatiles. If such a mechanism turns out to be unfeasible, the fluid-mediated alteration within meteoritic parent bodies was likely much more complex than currently thought and will require revision.

目前，人们还不清楚水、氮化合物和其他挥发性物质如何在太阳原行星盘中相互作用，并最终形成陆地海洋和大气。在这个项目中，我们重点研究太阳系最初一千万年中富铁金属颗粒与挥发性物质的反应。由于其高反应性，金属构成了对所涉及的原行星过程的理想矿物学探针。在球粒陨石中观察到的典型反应产物是富铁的硫化物和氧化物，例如磁黄铁矿、镍黄铁矿和磁铁矿。我们的目标是得出决定性的标准，以区分气-固相互作用和液-水蚀变作为此类与金属相关的矿物组合的起源机制，并且我们的目标是阐明所涉及的挥发性储层。特别是，我们将解决蒸发的多组分（类彗星）冰是否在原行星气固相互作用中发挥重要作用的尚未解决的突出问题。这是由新颖的含氮化物硫化物组合所暗示的，表明以前存在气态氨。我们将通过双重方法测试形成假设：（i）通过球粒陨石中与金属相关的矿物组合的矿物学和微观结构分析重建物理化学形成条件，（ii）通过对球粒陨石中气体-金属相互作用的新颖实验研究 使用氢气、硫化氢、水、氨和氮气的混合物的低压气体混合炉。透射电子显微镜 (TEM) 将成为一种核心分析工具，并辅以二次离子质谱 (SIMS)，用于氧、硫和氮的同位素分析。这些结果预计将大大增强我们对原行星相互作用和挥发性物质库的理解。如果能够证明蒸发的多组分冰参与其中，那么该过程及其物理化学条件将对太阳星云的局部氧化还原状态和原始有机物种的演化产生重要影响，这些原始有机物种可能包含在此类冰中，并可能与其他挥发物一起传递到早期地球。如果这种机制被证明是不可行的，那么陨石母体内由流体介导的改变可能比目前想象的要复杂得多，并且需要修改。