The Wigu Hill Carbonatite, located south of Uluguru Mountain, is amongst the REE-endowed carbonatites in Tanzania. The carbonatite comprises apatite dolomite carbonatite that has been locally brecciated and intruded by small bodies of mica dolomite carbonatite. These early carbonatites are fine to medium grained, poorly enriched in REE₂O₃ (< 0.4 wt%), and show elevated Nb (> 200 ppm). The early carbonatites are crosscut by REE-bearing carbonatite dikes that host pegmatitic, well-preserved pseudomorphs after burbankite. The REE-bearing carbonatites are characterised by high REE₂O₃ (6–10 wt%), and pseudomorphs that vary in colour and mineralogy, reflecting the dissolution of primary burbankite through reaction with evolving carbothermal fluids in two major phases; (1) early altered burbankite formed yellow-colored pseudomorphs typified by an assemblage of synchysite-(Ce) with high (La/Ce)_N - (La/Nd)_N ratios, barite, Ca-strontianite, calcite, and quartz; and (2) subsequent late alterations by highly evolved fluids resulted into green and pink-colored pseudomorphs consisting of synchysite-(Ce) with low (La/Ce)_N - (La/Nd)_N ratios, barite, Ca-strontianite, fluorite, calcite, quartz, apatite, monazite, and Al-REE-phosphates. The stable C-O and Mg isotopes signatures of dolomite across Wigu Hill indicate a pristine mantle source (δ¹³C_VPDB -4.1‰ to -6.2‰; δ¹⁸O_VSMOW +6.5‰ to + 7.31‰ and δ²⁶Mg -0.44 to + 0.19‰), and are locally modified by surface processes which resulted in bastnaesite enriched zones with up to 15 wt% REE₂O₃. Textural, geochemical, and stable isotope data tracks a polygenetic evolution of Wigu Hill with the main REE mineralization phase occurring at the end of magmatic phase as a result of magmatic fractionations. Reworking by carbothermal fluids and locally by surface process has resulted in REE enrichment.

威古山碳酸岩位于乌卢古鲁山以南，是坦桑尼亚富含稀土的碳酸岩之一。碳酸岩包括磷灰石白云石碳酸岩，其已经局部角砾化并被小块云母白云石碳酸岩侵入。这些早期碳酸岩为细粒至中等粒度，稀土元素 ₂ O ₃ (< 0.4 wt%) 富集度较低，并且 Nb 含量较高 (> 200 ppm)。早期碳酸岩被含稀土碳酸盐岩岩脉横切，这些岩脉在伯班岩之后含有伟晶岩、保存完好的假晶岩。含稀土碳酸盐岩的特征是高稀土元素 ₂ O ₃ (6–10 wt%)，以及颜色和矿物学各异的假晶，反映了原生 burbankite 通过反应溶解碳热流体分为两个主要阶段； (1) 早期蚀变的伯班石形成黄色假晶，其特征是具有高 (La/Ce) _N - (La/Nd) _N 比率的合晶石-(Ce) 组合，重晶石、钙菱锶矿、方解石和石英； (2) 随后高度演化流体的后期改变导致绿色和粉红色假晶体由合晶石-(Ce) 和低 (La/Ce) _N - (La/Nd) _N C _VPDB -4.1 ‰ 至 -6.2 ‰；δ ¹⁸ O _VSMOW +6.5‰ 至 + 7.31‰ 和 δ ²⁶ Mg -0.44 至 + 0.19‰)，并通过表面过程进行局部改性，形成氟碳铈矿富集区，含量高达 15 wt% REE ₂ O ₃ 。 结构、地球化学和稳定同位素数据追踪了 Wigu Hill 的多成因演化，由于岩浆分馏，主要稀土矿化阶段发生在岩浆阶段结束时。通过碳热流体和局部表面处理进行的再加工导致了稀土元素的富集。