The Chemical Evolution of Chondrite Components: Implications for Mixing in the Solar Nebula

球粒陨石成分的化学演化：对太阳星云混合的影响

• 批准号: 2442966
• 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: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2442966
• 关键词: Chemical; Evolution; Chondrite; Components; Implications

A crucial period during the history of any solar system is the first ~5 Myr following the ignition of the host star. Within this short time, the solar system transitions from a protoplanetary disk of dust and gas into a organised collection of orbiting planetary bodies. Within our solar system, a large number of meteorites formed during this early time and, as such, can act as a unique window into the processes that occurred during this transitionary period. One class of meteorite - called chondrites - are aggregates of millions of millimetre-sized solids that formed directly from our protoplanetary disk. As such, these meteorites can provide insight into the formation mechanisms and histories of the earliest solids in the solar system, and the processes by which these objects accumulated to form the first asteroid-sized bodies. The isotopic compositions of individual chondrite components (chondrules, refractory inclusions and matrix) suggest that the some of these solids are composed of mixtures of material that originates from different locations within the protoplanetary disk. For example, the titanium isotopic compositions of individual chondrules from carbonaceous chondrites argue that these objects contain remnants of refractory solids that are believed to have formed very close to Sun immediately following its ignition (Gerber et al, 2017). Moreover, the oxygen isotopic composition of the matrix of these meteorites has been used to argue that this component contains material that originates from the far reaches of the solar system (Bryson et al., 2019; under review). Together, these observations support the migration of primitive solids throughout the protoplanetary disk and suggest that the chemical composition of chondrites evolved through the incorporation of these different objects. Because large planetary bodies formed through the agglomeration of numerous asteroid-sized bodies, this migration and mixing could ultimately have played a significant role in generating the chemical composition of the different planetary bodies in our solar system. For instance, the inward flux of distal material has been proposed to be the source of water in hydrated asteroids and possibly the terrestrial planets (Gomes et al, 2005).Such mixing events in the early solar system will have imparted specific chemical signatures onto the individual components of chondrites. Importantly, these signatures will still exist in components that could be mixtures of materials with relatively similar isotopic compositions. As such, detailed measurements of the chemical compositions of individual chondrite components could be used to both explore previously proposed mixing trends as well as potentially identify new mixtures. The aim of this project is to conduct these measurements and use these compositions to constrain the mixing of different reservoirs within the early solar system. The results of these measurements will be used to investigate the extent to which the compositions of different planetary bodies evolved through the addition of material that originates from different regions of the solar system. As such, this project could uncover novel insight into the dynamics of solids throughout the solar system, the addition of dust and gas to the early solar nebula, and the origin and evolution of the chemical composition of a range of planetary bodies.

在任何太阳系历史上的关键时期是宿主恒星点火后的第一个〜5 Myr。在此短时间内，太阳系从灰尘和气体的原球盘转变为有组织的轨道行星体集合。在我们的太阳系中，在这段早期的时间内形成了大量的陨石，因此可以充当进入此过渡期间发生的过程的独特窗口。一类陨石 - 称为软骨 - 是直接从我们的原星盘形成的数百万毫米大小的固体的聚集体。因此，这些陨石可以洞悉太阳系中最早固体的形成机理和历史，以及这些物体积累以形成第一个小行星大小的物体的过程。单个软晶成分的同位素组成（软骨，难治性夹杂物和基质）表明，其中一些固体由材料混合物组成，这些材料的混合物源自原始磁盘内的不同位置。例如，来自碳质软管的单个软骨的各个软骨的钛同位素组合物认为，这些物体包含遗物的残余固体，这些固体被认为在其点火后立即形成非常接近阳光（Gerber等人，2017年）。此外，这些陨石的基质的氧同位素组成已被用来争辩说，该成分包含源自太阳系远处的材料（Bryson等，2019； Review）。总之，这些观察结果支持原始固体在整个原球磁盘中的迁移，并表明软件的化学组成通过掺入这些不同的物体而演变而成。由于通过众多小行星大小体的聚集形成的大行星体，这种迁移和混合最终可能在我们太阳系中不同行星体的化学组成中发挥了重要作用。例如，远端材料的内向通量已被认为是水合的小行星和可能的陆地行星中的水来源（Gomes等，2005）。在早期太阳系中，混合事件将赋予太阳系早期的混合事件，将其赋予特定的化学特异性特定的化学签名到Chondrites的各个组成部分。重要的是，这些特征仍然存在于可能是具有相对相似同位素组成的材料混合物中。因此，可以使用详细测量单个软晶成分的化学成分来探索先前提出的混合趋势，并可能识别新的混合物。该项目的目的是进行这些测量值，并使用这些组成来限制早期太阳系中不同储层的混合。这些测量结果将用于研究不同行星体的组成通过添加源自太阳系不同区域的材料而演变的程度。因此，该项目可以发现对整个太阳系固体动力学的新颖洞察力，向早期太阳星云中添加灰尘和气体，以及一系列行星体的化学成分的起源和演变。