AI 中文总结
本研究通过Ti、Cr、Mo同位素分析，揭示NC储层同位素变异性源于内盘尘埃组分的分馏与混合，而非热加工或外盘CC尘埃的持续添加，为太阳原行星盘早期演化提供了新证据。
AI 中文摘要
核合成同位素异常可用于区分非碳质（NC）和碳质（CC）类型陨石，且已揭示出相关的同位素变化，尤其是在NC天体之间。理解这种NC趋势的起源，对于识别产生NC同位素异质性的过程，以及利用这些同位素异常重建太阳原行星盘的早期演化都十分重要。我们报告了一组此前未被研究或仅被初步研究的陨石，以及从原始普通球粒陨石连续消解获得的酸浸出液的非质量相关Ti、Cr和Mo同位素组成。本研究中部分样本填补了此前NC趋势中明显的空白，表明这些空白反映了对更连续的同位素趋势的非代表性采样。整体陨石和浸出液表现出不同的同位素体系，说明NC同位素变异性并非源于原行星盘中前太阳载体的选择性热加工。NC趋势也不能反映CC尘埃从外盘向内盘的持续添加，因为形成时间较早和较晚的NC陨石显示出大致重叠的同位素组成。相反，我们发现NC同位素异质性最适合用化学和同位素上不同的尘埃组分之间的分馏和混合来解释，这与产生碳质球粒陨石之间同位素变异性的过程类似。在此基础上，我们认为内盘中存在亚结构，这种亚结构促进了不同尘埃组分之间的分馏和混合，并帮助保存了一个长寿命的尘埃储层，NC星子在很长一段时间内从该储层吸积形成。
英文摘要
Nucleosynthetic isotope anomalies allow distinguishing between non-carbonaceous (NC) and carbonaceous (CC) type meteorites, and have revealed correlated isotope variations especially among NC bodies. Understanding the origin of this NC trend is important for identifying the processes that produced the NC isotope heterogeneity, and for using these isotope anomalies to reconstruct the early evolution of the solar protoplanetary disk. We report mass-independent Ti, Cr, and Mo isotope compositions for a comprehensive set of previously not or only poorly investigated meteorites, as well as acid leachates obtained from the sequential digestion of primitive ordinary chondrites. Some of the samples investigated in this study fill previously identified apparent gaps in the NC trend, suggesting these gaps reflect unrepresentative sampling of a more continuous isotopic trend. Bulk meteorites and leachates exhibit distinct isotope systematics, indicating that the NC isotope variability does not reflect selective thermal processing of presolar carriers in the disk. The NC trend also cannot reflect the continuous addition of CC dust from the outer to the inner disk, because early- and late-formed NC meteorites display largely overlapping isotopic compositions. Instead, we find that the NC isotope heterogeneity is best accounted for by fractionation and mixing among chemically and isotopically distinct dust components, similar to the processes that produced the isotopic variability among carbonaceous chondrites. On this basis we argue for the presence of substructures in the inner disk, which facilitated fractionation and mixing among distinct dust components, and helped preserve a long-lived dust reservoir from which NC planetesimals accreted over an extended period of time.
CommentsAccepted for publication in Geochimica et Cosmochimica Acta (https://doi.org/10.1016/j.gca.2026.08.021)
