Carbonatite from the Arabian-Nubian Shield of Sudan occurs as dykes in the Nuba Mountains. It is composed of calcite with some feldspars, quartz and fluorite. CaO is the major constituent in this carbonatite and accordingly, it is classified as calico-carbonatite. The studied carbonatite shows exceptionally high concentrations of SrO (4.4 to 5.9 wt%). Ba, Pb and Y occur in relatively higher concentrations compared to other trace elements. Concentration of rare earth elements (ΣREEs) is relatively low (average 1550 ppm) compared to many primary igneous carbonatites. The chondrite-normalized REE patterns display higher light rare earth elements (LREEs) compared to heavy rare earth elements (HREEs) with slight negative Ce/Ce* and Eu/Eu* anomalies. The δ¹⁸OV-SMOW values range between 7.48 and 10.05‰, while δ¹³CV-PDB values vary from −6.24 to −7.38‰, which is close to the primary carbonatites values.

Occurrence of carbonatite as dykes with cumulate and triple junction textures, plot of the carbonatite in the true carbonatite fields of the Ba-Sr and Ba + Sr-REE + Y diagrams, igneous-derived δ¹³CV-PDB and δ¹⁸OV-SMOW values and high (La/Yb)_N ratios indicate its primary igneous origin. The strong positive correlation between REEs and Sr suggests the occurrence of these elements as secondary strontianite, which was confirmed by SEM and EDX analyses. This might indicate that the enrichment of REEs and Sr in the studied carbonatite is not from the primary magma and most probably took place during a sub-solidus metasomatic process after the carbonatite emplacement.

来自苏丹阿拉伯-努比亚盾牌的碳酸盐岩以堤坝的形式出现在努巴山。它由方解石和一些长石，石英和萤石组成。CaO是该碳酸盐岩的主要成分，因此，它被分类为钙碳质碳酸盐岩。所研究的碳酸盐岩显示出异常高的SrO浓度（4.4至5.9 wt％）。与其他微量元素相比，Ba，Pb和Y的浓度相对较高。与许多原生火成岩碳酸盐岩相比，稀土元素（ΣREEs）的浓度相对较低（平均1550 ppm）。与重稀土元素（HREE）相比，球粒陨石归一化REE模式显示出较高的轻稀土元素（LREE），而Ce / Ce *和Eu / Eu *异常略有负。的δ ¹⁸ OV-SMOW值的范围和7.48 10.05‰之间，而δ¹³ CV-PDB值在-6.24至-7.38‰之间变化，接近于主要碳酸盐值。

碳酸盐的发生与累积和三结纹理，在BA-Sr和Ba + SR-REE + Y图的真正碳酸盐字段碳酸盐的情节堤坝，火成岩衍生的δ ¹³ CV-PDB和δ ¹⁸ OV-SMOW值和高（La / Yb）_N比表明其主要火成因。稀土元素和锶之间的强正相关表明这些元素作为二级锶矿存在，这已通过SEM和EDX分析得到了证实。这可能表明所研究的碳酸盐岩中的REE和Sr富集不是来自原岩浆，而是最有可能发生在碳酸盐岩植入后的次固相交代过程中。