Abstract The rare earth element (REE) mineralization of Gakara (Burundi) has first been discovered in 1936 and has periodically been the subject of geological studies, at times when the exploitation of bastnasite-(Ce) and monazite-(Ce) was economically interesting. This study focuses on the establishment of a mineral paragenesis for Gakara, with special attention to the REE-bearing phases, to understand the formation history of the deposit. The paragenesis can be subdivided into 3 stages: primary ore deposition, brecciation stage and supergene alteration. Evidence for fenitization processes (i.e. pinkish-red cathodoluminescence of K-feldpar, brecciation stage) and the strong enrichment of light REEs in bastnasite and monazite substantiate the hypothesis of a structurally controlled hydrothermal mineralization with a strong carbonatitic affinity. This likely confirms the association of the Gakara REE deposit with the Neoproterozoic alignment of alkaline complexes and carbonatites along the present-day Western Rift. It suggests a direct link with a – currently unidentified – carbonatitic body at depth, possibly derived from a predominantly metasomatized lithospheric mantle.

中文翻译：

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Gakara（布隆迪）稀土元素矿化的矿物学和地球化学研究

摘要 Gakara（布隆迪）的稀土元素 (REE) 矿化于 1936 年首次被发现，并定期成为地质研究的主题，当时氟碳铈矿 (Ce) 和独居石 (Ce) 的开采具有经济意义。 . 本研究侧重于为 Gakara 建立矿物共生关系，特别关注含 REE 相，以了解矿床的形成历史。共生作用可细分为3个阶段：原生矿沉积、角砾化阶段和表生蚀变。非硝化过程的证据（即钾长石的粉红色阴极发光，角砾岩化阶段）和氟碳铈矿和独居石中轻稀土的强烈富集证实了结构控制的热液矿化具有很强的碳酸盐亲和性的假设。这可能证实了 Gakara REE 矿床与现今西部裂谷中碱性复合物和碳酸岩的新元古代排列的关联。它表明与一个目前尚未确定的深部碳酸岩体有直接联系，可能来自主要交代化的岩石圈地幔。