Tongo Gandima is an area located in the southeastern part of the Bétaré Oya Gold district (Eastern Cameroon). Geochemical investigations on rare metals (TiO₂, Th, Y, and rare‐earth elements [REE]) were carried out on sample types (source rocks, unconsolidated fine‐grained sediments, and concentrated sediments) using X‐ray diffraction (XRD), X‐ray fluorescence (XRF), inductively coupled plasma‐mass spectrometry (ICP‐MS), and scanning electron microscope equipped with EDAX spectrometer (SEM‐EDS) methods. In this study, five layers of river terraces were selected (organic matter layer, clayey layer, fine sandy layer, coarse sandy layer, and gravel layer). One of them, the gravel layer, is mineralized. TiO₂, Zr, and REE are more enriched in monzonites than in granites. Unconsolidated sediments derive mainly from the erosion of weathered materials developed on monzonites and granites. The mineral assemblage of fine‐grained sediments from the gravel layer is muscovite, kaolinite, quartz, rutile, smectite, and others, and the average concentrations in Th, Zr, and Y are high. Fifty concentrated fractions from the same samples were analysed separately and their mineralogy is smectite, kaolinite, gibbsite, muscovite, quartz, rutile, anatase, zircon, titanomagnetite, and ilmenite. The heavy mineral fractions are opaque minerals, biotite, zircon, rutile, tourmaline, garnet, diopside, zoisite, and kyanite. TiO₂, Zr, Th, Y, and REE contents are high. The REE oxides (REO) total grade ranges from 0.0088 to 15.66 wt%, marked by LREO‐abundance, especially in La₂O₃, Ce₂O₃, Pr₂O₃, and Nd₂O₃. The Tongo Gandima REO deposit was classified as LREO‐dominated type. The chondrite‐normalized REE patterns exhibit strong negative Eu anomalies; their V‐shaped patterns are typical of ore varieties. The abundant TiO₂, Zr, Y, Th, and REE might have been influenced by surface processes (peneplanation and chemical weathering) and variations in sediment grain size. SEM‐EDS data reveal that apatite with Ce‐ and La‐dominant, monazite‐(Ce), and Ce‐Mn‐bearing ilmenite are rare metal‐bearing minerals. This study demonstrates that the economic importance of the alluvial‐fluvial placers from Tongo Gandima results from their high Ti, Zr, Th, Y, and REE contents.

中文翻译：

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喀麦隆东部BétaréOya金区Tongo Gandima的未固结细颗粒沉积物中的TiO2-Zr-Th-Y-Y稀土元素矿床

Tongo Gandima是位于BétaréOya Gold黄金区（喀麦隆东部）东南部的地区。使用X射线衍射（XRD）对样品类型（源岩，未固结的细颗粒沉积物和浓缩沉积物）进行了稀有金属（TiO ₂，Th，Y和稀土元素[REE]）的地球化学研究。，X射线荧光（XRF），电感耦合等离子体质谱（ICP-MS）和配备EDAX光谱仪（SEM-EDS）方法的扫描电子显微镜。在这项研究中，选择了五层河阶地（有机物层，黏土层，细砂层，粗砂层和砾石层）。其中之一是砾石层，已矿化。二氧化钛₂，锆和稀土元素在花岗岩中比在花岗岩中富集更多。未固结的沉积物主要来自于蒙脱石和花岗岩上风化物质的侵蚀。来自砾石层的细颗粒沉积物的矿物组合是白云母，高岭石，石英，金红石，蒙脱石等，并且Th，Zr和Y中的平均浓度很高。分别分析了来自相同样品的50种浓缩馏分，它们的矿物学是蒙脱石，高岭石，菱镁矿，白云母，石英，金红石，锐钛矿，锆石，钛磁铁矿和钛铁矿。重矿物成分是不透明矿物，黑云母，锆石，金红石，电气石，石榴石，透辉石，硅酸盐和蓝晶石。二氧化钛₂，Zr，Th，Y和REE含量较高。稀土氧化物（REO）的总品位范围为0.0088至15.66 wt％，具有LREO丰度，特别是在La ₂ O ₃，Ce ₂ O ₃，Pr ₂ O ₃和Nd ₂ O _3中。Tongo Gandima REO矿床被归类为LREO为主的类型。球粒陨石归一化的REE模式表现出强烈的负Eu异常。它们的V形图案是典型的矿石品种。丰富的TiO ₂，Zr，Y，Th和REE可能已受表面过程（渗碳和化学风化）和沉积物粒径变化的影响。SEM-EDS数据表明，磷灰石中铈和镧为主，独居石（Ce）和铈铈锰钛铁矿是稀有的金属矿物。这项研究表明，汤戈甘地马冲积河流冲积砂的经济重要性是由于其高Ti，Zr，Th，Y和REE含量造成的。