Mantle peridotites entrained as xenoliths in the lavas of Ngao Bilta in the eastern branch of the continental Cameroon Line were examined to constrain mantle processes and the origin and nature of melts that have modified the upper mantle beneath the Cameroon Line. The xenoliths consist mainly of lherzolite with subordinate harzburgite and dunite. They commonly contain olivine, orthopyroxene, clinopyroxene and spinel although the dunite is spinel-free. Amphibole is an essential constituent in the lherzolites. Mineral chemistry differs between the three types of peridotite: olivines have usual mantle-like Mg# of around 90 in lherzolites, but follow a trend of decreasing Mg# (to 82) and NiO (to 0.06 ​wt.%) that is continuous in the dunites. Lherzolites also contain orthopyroxenes and/or clinopyroxenes with low-Mg#, indicating a reaction that removes Opx and introduces Cpx, olivine, amphibole and spinel. This is attributed to reaction with a silica-undersaturated silicate melt such as nephelinite or basanite, which originated as a low-degree melt from a depleted source as indicated by low Al₂O₃ and Na₂O in Cpx and high Na₂O/K₂O in amphibole. Thermobarometric estimates place the xenoliths at pressures of 11–15 ​kbar (35–50 ​km) and temperatures of 863–957 ​°C, along a dynamic rift geotherm and shallower than the region where carbonate melts may occur. The melt/rock reactions exhibited by the Ngao Bilta xenoliths are consistent with their peripheral position in the eastern branch of the Cameroon Volcanic Line in an area of thinned crust and lithosphere beneath the Adamawa Uplift.

在喀麦隆线大陆东部分支Ngao Bilta的熔岩中夹带为异岩的地幔橄榄岩被检查以限制地幔过程，融化了喀麦隆线下方上地幔的融化物的起源和性质。异种岩主要由锂铁矿和次要的哈兹贝格石和榴辉岩组成。它们通常含有橄榄石，邻苯二甲烯，斜铁基吡啶和尖晶石，尽管榴n石不含尖晶石。角闪石是锂铁矿中必不可少的成分。三种橄榄石的矿物化学不同：橄榄石在锂铁矿中通常具有约90的地幔状Mg＃，但遵循Mg＃（降至82）和NiO（至0.06 wt。％）减少的趋势dunites。锂沸石还含有具有低Mg＃的邻辉石和/或斜辉石，表示去除了Opx并引入了Cpx，橄榄石，闪石和尖晶石的反应。这归因于与二氧化硅不饱和硅酸盐熔体（如霞石或玄武岩）发生反应，这是由于贫化源中的低度熔体（如低Al所表示）₂ ö ₃和Na ₂ ○在单斜辉石和高的Na ₂ O /ķ ₂ ○在闪石。热压法估算使异岩体沿动态裂谷地热处于11-15 kbar（35-50 km）的压力和863-957°C的温度下，并比可能发生碳酸盐熔融的区域浅。Ngao Bilta异种岩表现出的熔体/岩石反应与其在喀麦隆火山线东部分支中阿达玛瓦瓦隆升以下的地壳和岩石圈变薄区域的外围位置一致。