Origin of heterogeneous isotope distribution for heavy elements in the early solar system

我们研究了太阳系早期重元素非均相同位素分布的起源。利用TIMS对球粒陨石和非球粒陨石的大块岩石以及球粒陨石成分（如CAIs、球粒、酸渗滤液）进行了Sr、Nd、Te和Mo的高精度同位素分析。我们发现，只有在1300K ~ 1600K之间50%冷凝温度的中难熔元素（如Cr、Mo、Sr）存在行星尺度的同位素非均质性。这意味着中等难熔性元素的同位素非均质性是由与热处理、物质运输和原行星盘中混合有关的尘埃颗粒的动力学历史造成的，而不是假设超新星注入和/或粒度分选等过程。

We have investigated the origin of heterogeneous isotope distribution for heavy elements in the early solar system. Highly precise isotope analyses of Sr, Nd, Te, and Mo were conducted using TIMS for bulk rocks of chondrites and nonchondrites, as well as for chondrite components (e.g., CAIs, chondrules, acid leachates). We found that planetary scale isotope heterogeneities exist only for moderately refractory elements with 50% condensation temperature between 1300K to 1600K (e.g., Cr, Mo, Sr). This implies that isotope heterogeneities for moderately refractory elements were created by a dynamical history of dust grains related to thermal processing, material transportation, and mixing in the protoplanetary disk prior to planetesimal formation, rather than assuming processes such as supernova injection and/or grain-size sorting.