Heterogeneity in isotopic compositions within the protoplanetary disc has been demonstrated for a number of elements measured in extra-terrestrial materials, mostly based on chondrite meteorite analyses. However, precise ¹⁸²Hf-¹⁸²W and ²⁶Al-²⁶Mg ages of iron meteorites, achondrites, and chondrules show that chondrites accreted later than achondrites and therefore do not strictly represent the early (<2 Ma) solar system composition. Here we present the Nd mass-independent stable isotopic compositions of a suite of diverse achondrites to better constrain the Nd isotope evolution of the early solar system. Carbonaceous (C) achondrites are indistinguishable from their chondritic counterpart. However, early formed planetesimals as sampled by silicate-rich non-carbonaceous (NC) achondrite meteorites have higher ¹⁴⁵Nd/¹⁴⁴Nd and ¹⁴⁸Nd/¹⁴⁴Nd ratios (3.9 < ${\mu }^{145}$Nd < 11.0 and 9.1 < ${\mu }^{148}$Nd < 17.9 in part per million deviation, or ${\mu }^{\mathrm{i}}$Nd) compared to NC chondrites (2.7 < ${\mu }^{145}$Nd < 3.3 and 2.2 < ${\mu }^{148}$Nd < 8.1). Moreover, the three terrestrial planets for which we have samples available (Earth, Mars, and the Moon) as well as the silicate inclusions from the non-magmatic IIE iron meteorite Miles present a systematic deficit in ${\mu }^{145}$Nd and ${\mu }^{148}$Nd compared to early-formed NC achondrites. Unlike chondrites, the Nd anomalies in achondrites are not correlated to the heliocentric distance of accretion of their respective parent bodies as inferred from redox conditions. Chronological constraints on planetesimal accretion suggest that Nd (and other elements such as Mo and Zr) nucleosynthetic compositions of the inner part of the protoplanetary disc significantly changed around 1.5 Ma after Solar System formation due to thermal processing of dust in the protoplanetary disc. This relatively late event coincides with the beginning of chondrule formation or at least their preservation. Terrestrial planets formed subsequently by a complex accretion regime during several million years. Therefore, two scenarios are envisioned considering the reported Nd isotope composition of early planetesimals: 1) Terrestrial planets accreted mostly chondritic material similar in composition to enstatite chondrites, or 2) early planetesimals constitute substantial parts of terrestrial planets building blocks mixed with highly thermally processed material enriched in s-process, still unsampled by meteorites.

对于在地球外物质中测量到的许多元素，已经证明了原行星盘内同位素组成的非均质性，这些元素主要基于球粒陨石分析。但是，精确的¹⁸² Hf- ¹⁸² W和²⁶ Al- ²⁶镁年龄的铁陨石，无定形体和球粒状体表明，球状体的沉积比无定形体晚，因此不能严格代表早期（<2 Ma）的太阳系组成。在这里，我们介绍了一组不同的陨石的Nd质量独立稳定同位素组成，以更好地约束早期太阳系的Nd同位素演化。碳质（C）硬质子石与它们的软骨状晶石没有区别。但是，通过富含硅酸盐的非碳质（AC）无定形陨石陨石所采样的早期形成的小行星具有更高的¹⁴⁵ Nd / ¹⁴⁴ Nd和¹⁴⁸ Nd / ¹⁴⁴ Nd比（3.9 <${\mu }^{145}$Nd <11.0和9.1 < ${\mu }^{148}$Nd <17.9，百万分之一偏差，或 ${\mu }^{\mathrm{一世}}$Nd）与NC球粒陨石（2.7 < ${\mu }^{145}$Nd <3.3和2.2 < ${\mu }^{148}$Nd <8.1）。此外，我们有可用的三个地球行星（地球，火星和月球），以及来自非岩浆IIE陨石Miles的硅酸盐包裹体，都在系统上造成了赤字。${\mu }^{145}$钕和 ${\mu }^{148}$Nd与早先形成的NC陨石相比。与球粒陨石不同，从氧化还原条件推断，球粒陨石中的Nd异常与它们各自母体的增生的日心距离无关。对行星生长的时间限制表明，太阳系形成后，由于对原行星盘内灰尘的热处理，原行星盘内部分的Nd（以及其他元素，如Mo和Zr）的核合成成分在1.5 Ma左右发生了显着变化。这种相对较晚的事件与软骨形成的开始或至少它们的保存相吻合。几百万年来，地球行星是由复杂的吸积机制形成的。因此，考虑到已报道的早期行星小行星Nd同位素组成，可以设想两种情况：s-进程，仍未通过陨石采样。