Rare earth elements (REEs) mobilize, fractionate, and are re-distributed during supergene processes, and thus provide a powerful tool with which to quantitatively reconstruct the effects of chemical weathering. Moreover, under certain conditions, the REEs can concentrate to levels in the regolith sufficient to form giant regolith-hosted REE deposits, that are now responsible for much of the World’s production of heavy REEs (HREEs). Understanding the supergene behavior of the REEs is an important first step towards applying the REEs as a geochemical tool and meeting the growing global demand of the REEs.

Thermodynamic calculations predict that dissolution of the main REE minerals in REE-rich protoliths, namely synchysite-(Y), gadolinite-(Y), hingganite-(Y), yttrialite-(Y), allanite-(Ce), eudialyte, chevkinite-(Ce), britholite, euxenite and loparite-(Ce), should occur spontaneously during weathering. It therefore follows that a high abundance of these minerals in the protolith implies high mobility of the REE during weathering and consequently a high potential for the discovery of economic REE resources. Dissolution of apatite is promoted by metamictization or structural distortion and could be also important at low pH. In contrast, some LREE-fluorocarbonate minerals, notably bastnäsite-(Ce) and parisite-(Ce), and monazite-(Ce) are likely thermodynamically stable in acidic environments. Thus, they would be preserved in the regolith. Zircon, titanite, aeschynite, fergusonite, and xenotime-(Y) are resistant to acidic dissolution, consistent with their common occurrence as residual minerals.

In the cases of the world-class regolith-hosted REE deposits in South China, the groundwater is mildly acidic to circumneutral and carbonate-rich. The REEs are consequently transported dominantly as hydrated cations and carbonate complexes, depending on the pH. The general inheritance of the REE pattern of the regolith water in the clay-sorbed fraction in the regolith indicates that the REEs in regolith are scavenged from the regolith water. Elemental anomalies of specific REEs in the clay-sorbed fraction are very likely caused by an anomalously high REECO₃⁺ fraction in the corresponding regolith water, suggesting a preferential uptake of the REECO₃⁺ complexes by the clay minerals, feasibly by halloysite through intercalation as interlayer complexes. This reaction is expected to be particularly important for the sorption and enrichment of the HREEs in the regolith. Depending on the pH and carbonate concentration of the water, surface complexation on clay minerals or interlayer intercalation particularly in halloysite control the pattern of REE enrichment. Mixing of the regolith water with the alkaline and carbonate-rich aquifer groundwater increases the pH and carbonate concentration and, in turn, affects the ability of the mixed water to transport the HREEs. Interplay of aqueous complexation with the regolith mineralogy significantly affects the REE fractionation and re-distribution during groundwater-regolith interaction.

稀土元素（REE）在超基因过程中动员，分级和重新分布，因此提供了一种强大的工具，可用于定量重建化学风化的影响。此外，在某些条件下，稀土元素可以集中到重金属矿中的水平，足以形成巨大的由重矿物组成的稀土矿床，这些矿床现在是世界上大量重稀土（HREE）生产的原因。了解稀土元素的超基因行为是将稀土元素用作地球化学工具并满足日益增长的稀土元素全球需求的重要的第一步。

热力学计算表明，主要稀土元素矿物在富含稀土元素的原生石中的溶解，即斜纹岩-（Y），辉长岩-（Y），兴安岩-（Y），钇铁矿-（Y），尿囊石-（Ce），真辉岩，雪佛石-（Ce），水钠钙榴石，硬石膏和钙铝石-（Ce），在风化过程中应自发发生。因此，可以得出结论，原生岩中这些矿物的丰富含量意味着风化过程中REE的高迁移率，因此具有发现经济REE资源的巨大潜力。磷灰石的溶解会因成矿作用或结构变形而促进，并且在低pH值下也可能很重要。相反，一些轻稀土碳酸盐矿物，尤其是bastnäsite-（Ce）和parisite-（Ce）以及独居石（Ce）在酸性环境中可能具有热力学稳定性。因此，它们将保留在重石块中。锆石

就华南地区世界级的由重碎屑岩为主的稀土元素矿床而言，地下水为弱酸性至周围环境且富含碳酸盐。因此，取决于pH值，稀土元素主要以水合阳离子和碳酸盐复合物的形式运输。在白云母中粘土吸附的部分中的白云母水的REE模式的一般遗传表明，从白云母水中清除了白云母中的REE。黏土吸附馏分中特定REE的元素异常很可能是由相应的硬水中异常高的REECO ₃ ⁺馏分引起的，表明优先吸收REECO ₃ ⁺粘土矿物形成的复合物，可能是埃洛石通过夹层作为层间复合物。预期该反应对于重结晶物中HREE的吸附和富集特别重要。根据水的pH值和碳酸盐浓度，粘土矿物上的表面络合或层间插层（尤其是埃洛石）可控制REE富集的模式。重水石块水与碱性和富含碳酸盐的含水层地下水的混合会增加pH和碳酸盐的浓度，进而影响混合水运输HREE的能力。含水络合物与go石矿物学的相互作用显着影响了地下水-re石相互作用期间的稀土元素分馏和再分布。