稀土元素作为中国关键战略矿产资源，其成矿机制研究具有重要科学价值。已有研究证实黔东南—湘西地区寒武系牛蹄塘组黑色页岩赋存大型重晶石矿床并伴生显著稀土富集现象，但稀土元素的来源、赋存状态以及富集机理仍不明晰。该研究选取天柱重晶石矿床典型富稀土层位，系统开展激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）面扫描成像分析，结合微区X射线衍射（XRD）技术，揭示稀土元素的来源、赋存状态与富集机制。综合研究表明：（1）稀土配分模式与现代海水—孔隙水体系呈现高度一致性，高富集区Y/Ho比值、Ce/Ce*及Eu/Eu*值显示典型海水成因特征，局部存在陆源输入信号；（2）P-Ca-REY三元相关性分析揭示Ca含量与REY丰度呈显著正相关关系（R2=0.80），而Ca-P、REY-P间无显著成因联系，微区X射线衍射（XRD）分析证实稀土元素主要赋存于自生碳酸盐矿物晶格；（3）提出”海水源—成岩富集”机制，阐明重晶石成岩过程中硫酸根氧化有机质释放碳酸根，驱动稀土元素通过类质同象置换方式在碳酸盐矿物中选择性富集。文章通过多维度技术方法，首次阐明天柱地区稀土元素的海水来源属性、碳酸盐矿物赋存载体特征及成岩活化富集机制，为揭示黑色页岩系中稀土元素富集规律提供了新的认识。

Rare earth elements and yttrium represent key strategic mineral resources in China, and the research on their metallogenic mechanisms hold significant scientific importance. Previous studies have confirmed the presence of large barite deposits accompanied by notable REY enrichment in the Cambrian Niutitang Formation black shales of the Southeastern Guizhou- Western Hunan region. But the sources, occurrence states, and enrichment mechanisms of REY remain poorly constrained. This study selected REY-rich layers from the Tianzhu barite deposit and systematically applied laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) mapping and micro-X-ray diffraction (μ-XRD) to investigate the origin, occurrence, and enrichment processes of REY. Integrated analyses reveal: (1) REY distribution patterns exhibit strong consistency with modern seawater-pore water systems, where elevated Y/Ho ratios, Ce/Ce*, and Eu/Eu* in high-REY zones indicate predominant seawater-derived signatures, with minor terrigenous inputs; (2) P-Ca-REY ternary correlation analysis demonstrates a significant positive relationship between Ca content and REY abundance (R2= 0.80), whereas no significant causal links exist between Ca-P or REY-P. Micro-XRD confirms that REY primarily reside in authigenic carbonate crystal lattices; (3) A“seawater sourcediagenetic enrichment” model is proposed, elucidating that sulfate radicals in barite oxidize organic matter during diagenesis, releasing carbonate ions that promote Ca2+-carbonate precipitation, thereby driving REY enrichment via isomorphic substitution in carbonate minerals. Through multidisciplinary approaches, this study proposes the seawater-derived origin, carbonate-hosted occurrence, and diagenetic activation mechanisms of REY in the Tianzhu deposit, providing new insights into the enrichment patterns of REY in black shale systems.