Qian Lijun, Ou Lihua, Li Guoxin, Xiao Xuepeng, Qian Bo
School of Civil and Hydraulic Engineering, Xichang University, Xichang, China.
Institute of Earth and Planetary Sciences, Chengdu University of Technology, Chengdu, China.
PLoS One. 2025 Jul 29;20(7):e0329138. doi: 10.1371/journal.pone.0329138. eCollection 2025.
The Kuanyu ion-adsorption rare earth element (REE) deposit, Sichuan's first economically viable resource of its type, remains underexplored in terms of REE fractionation and enrichment mechanisms within its weathering profiles. This study systematically resolves REE speciation patterns and light-to-heavy REE (LREE/HREE) differentiation processes, advancing the metallogenic framework fo r such deposits. Analytical results demonstrate: (1) A vertically progressive enrichment of LREE-dominated REE concentrations from bedrock to topsoil, with the fully weathered layer serving as the primary enrichment zone; (2) Weathering of primary REE-bearing minerals and subsequent secondary mineral formation as drivers of elemental redistribution; (3) Contrasting controls by clay minerals, iron-manganese oxides, and humic acids-clay minerals preferentially adsorb LREEs, while iron-manganese oxides exhibit stronger HREE affinity through inner-sphere complexation, and humic acids enhance HREE mobility via stable complex formation. These findings establish iron-manganese oxides and organic ligands as dual regulators of REE fractionation, refining predictive models for ion-adsorption REE exploration in granitic weathering systems.
四川首个具有经济可行性的离子吸附型稀土元素（REE）矿床——冕宁稀土矿床，其风化剖面内的稀土元素分馏和富集机制仍未得到充分研究。本研究系统地解析了稀土元素的形态模式和轻稀土到重稀土（LREE/HREE）的分异过程，推进了此类矿床的成矿框架。分析结果表明：（1）从基岩到表土，以轻稀土为主的稀土元素浓度呈垂直递进富集，全风化层为主要富集带；（2）原生含稀土矿物的风化及随后次生矿物的形成是元素重新分布的驱动因素；（3）粘土矿物、铁锰氧化物和腐殖酸的控制作用不同——粘土矿物优先吸附轻稀土，而铁锰氧化物通过内圈络合表现出更强的重稀土亲和力，腐殖酸通过形成稳定络合物增强重稀土的迁移性。这些发现确立了铁锰氧化物和有机配体作为稀土元素分馏的双重调节剂，完善了花岗岩风化系统中离子吸附型稀土勘探的预测模型。
