Abstract The Ntem Complex represents the northwestern margin of Congo Craton in southern Cameroon. It consists mainly of charnockites, TTG suites, potassic grantitoids, minor supracrustal and mafic rocks. The latter include gabbronorite enclave or sill, gabbro and dolerite dykes. The metagabbro are basaltic to andesitic in composition and show geochemical features of low-La Archean tholeiitic basalts, and LREE-depleted (LaN/SmN Ta values similar to modern intraplate continental basalts and intermediate-La Archean tholeiitic basalt, least affected by contamination from granitic continental crust. The partial melting of low-to high-K mafic rocks of oceanic and continental arc affinity generated the charnockites and low−/medium-pressure TTGs. The potassic granites were formed by partial melting of charnockite or TTG, and inherited many geochemical features of their sources. New LA–ICP–MS U Pb zircon dates suggest that the charnockites and TTG suites formed at ~3155–2850 Ma. The gabbro intrusion was dated at 2866 ± 6 Ma. Migmatisation of TTG-gneiss was coeval whit the regional high–grade metamorphism event at 2843 ± 7 Ma. The potassic granites were probably crystallized at ~2758 Ma. The garnet-whole rock Sm Nd age of 2744 ± 31 Ma may represent the age of the second anatexis event coeval with D2 deformation. Literature data indicate the disruption or open isotopic systems in the Ntem Complex around 2500–2600 Ma.

中文翻译：

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LA-ICP-MS锆石U Pb定年、Lu Hf、Sm Nd年代学和Sangmelima花岗岩-绿岩地体中太古代基性和长英质岩浆岩的构造背景，Ntem复合体（喀麦隆南部）

摘要 Ntem 杂岩体代表了喀麦隆南部刚果克拉通的西北边缘。它主要由charnockite，TTG套件，钾质花岗岩，次要上壳和镁铁质岩石组成。后者包括辉长岩飞地或窗台、辉长岩和辉绿岩脉。变长岩在成分上为玄武质至安山质，并显示出低拉太古代拉斑玄武岩的地球化学特征，且 LREE 贫化（LaN/SmN Ta 值类似于现代板内大陆玄武岩和中拉太古代拉斑玄武岩，受花岗岩污染影响最小大陆地壳。具有海洋和大陆弧亲和性的低至高 K 基性岩的部分熔融生成了硬镁石和中低压 TTG。钾质花岗岩是由硬镁石或 TTG 部分熔融形成的，并继承了其来源的许多地球化学特征。新的 LA-ICP-MS U Pb 锆石日期表明，charnockite 和 TTG 套件形成于~3155-2850 Ma。辉长岩侵入的年代为 2866 ± 6 Ma。TTG-片麻岩的混杂作用与2843±7 Ma的区域高级变质事件同时发生。钾质花岗岩可能在~2758 Ma 结晶。2744±31 Ma的石榴石-全岩Sm Nd年龄可能代表与D2变形同时期的第二次熔沸事件的年龄。文献数据表明 Ntem 复合体在 2500-2600 Ma 左右发生了破坏或开放的同位素系统。TTG-片麻岩的混杂作用与2843±7 Ma的区域高级变质事件同时发生。钾质花岗岩可能在~2758 Ma 结晶。2744±31 Ma的石榴石-全岩Sm Nd年龄可能代表与D2变形同时期的第二次熔沸事件的年龄。文献数据表明 Ntem 复合体在 2500-2600 Ma 左右发生了破坏或开放的同位素系统。TTG-片麻岩的混杂作用与2843±7 Ma的区域高级变质事件同时发生。钾质花岗岩可能在~2758 Ma 结晶。2744±31 Ma的石榴石-全岩Sm Nd年龄可能代表与D2变形同时期的第二次熔沸事件的年龄。文献数据表明 Ntem 复合体在 2500-2600 Ma 左右发生了破坏或开放的同位素系统。