During subaerial chemical weathering, submarine weathering and other intracrustal processes, SmNd chemical fractionation remains uncertain, while a little is known about the conditions, scale and magnitude, specific processes and actual mechanism for possible SmNd fractionation. Here, an in situ terra rossa weathering profile developed on dolostone is chosen for the study. Based on sequential extraction experiments and measurements of the mineral and geochemical compositions including SrNd isotopic compositions, we suggest that subaerial chemical weathering not only leads to considerable SmNd mobilization, redistribution and secondary enrichment, but also gives rise to extreme SmNd fractionation, apparent ¹⁴³Nd isotope homogenization, nearly complete resetting of the ¹⁴⁷Sm¹⁴³Nd isotope system, anomalous initial ¹⁴³Nd/¹⁴⁴Nd ratios, and meaningless ¹⁴³Nd model age (T_DM) for weathering products. We found that the lanthanide tetrad effect, rather than mineralogical control, is responsible for the observed substantial SmNd fractionation and for the other rare earth element fractionation. Under domination of the lanthanide tetrad effect, the mobility of Sm is preferential to that of Nd during their migration in the form of dissolved organic complexes. Our results also illustrate that resetting of the ¹⁴⁷Sm¹⁴³Nd isotope system in weathering products is controlled by the combined effect of the extraneous dissolved SmNd input and additional SmNd fractionation. Finally, we argue that similar scenarios may occur in submarine weathering, diagenesis and other geological processes.

在航空化学风化，海底风化和其他地壳内过程中，Sm Nd化学分馏仍不确定，尽管对可能的Sm Nd分馏的条件，规模和幅度，具体过程和实际机理知之甚少。在这里，研究选择了在白云岩上发育的原位terra rossa风化剖面。基于连续抽提实验和对包括Sr Nd同位素组成的矿物和地球化学成分的测量，我们认为，航空化学风化不仅会导致大量Sm Nd的动员，重新分布和二次富集，而且还会导致极端的Sm Nd分馏，明显¹⁴³Nd同位素均质化，¹⁴⁷ Sm ¹⁴³ Nd同位素系统几乎完全重置，初始¹⁴³ Nd / ¹⁴⁴ Nd比例异常以及对风化产品无意义的¹⁴³ Nd模型年龄（T _DM）。我们发现，镧系元素四重作用而不是矿物学控制是造成观察到的大量Sm Nd分馏和其他稀土元素分馏的原因。在镧系元素四价效应的控制下，Sm在迁移过程中以溶解的有机络合物形式优先于Nd迁移。我们的结果还表明，重置¹⁴⁷ Sm ¹⁴³风化产物中的Nd同位素系统受外部溶解的Sm Nd输入和额外的Sm Nd分馏的综合作用控制。最后，我们认为在海底风化，成岩作用和其他地质过程中可能会发生类似的情况。