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首页> 外文期刊>Journal of African Earth Sciences >The Pan-African post-collision Hossere Mana plutonic complex and associated Gapi Stock (Western Cameroon Domain, Cameroon): Petrology, mineralogy and geochemistry
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The Pan-African post-collision Hossere Mana plutonic complex and associated Gapi Stock (Western Cameroon Domain, Cameroon): Petrology, mineralogy and geochemistry

机译：泛非碰撞后的Hossere Mana岩体复合体和相关的Gapi储层（喀麦隆西部喀麦隆地区）：岩石学，矿物学和地球化学

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In the Cameroon Pan-African orogenic belt, the West Cameroon Domain (WCD) is characterized by the apparent lack of Archean-Paleoproterozoic relicts, the development of Neoproterozoic basins and abundant plutonic massifs. The Hossere Mana plutonic complex (HMPC) and the Gapi gabbroic stock are located in the vicinity of the Cretaceous Ngaou Boh granite complex and the Neogene Tchabal Gangbada basanite-trachyte-rhyolite volcanic plateau. They comprise clinopyroxene + amphibole +/- olivine leucogabbro, clinopyroxene + amphibole monzogabbro, biotite + amphibole +/- clinopyroxene monzodiorite, porphyritic and foliated biotite +/- muscovite monzogranite. Two parallel trends of Mg#, displayed by leucogabbro (0.66-0.61) monzogabbro (0.57-0.37), and by monzodiorite (0.66-0.55) -monzogranite (0.47-0.33), evidence two contrasting igneous suites, magnesian tholeiitic and magnesian high-K alkali-calcic to talc-alkaline (I-type). Primitive mantle-normalized patterns of the tholeiitic suite are fractionated, with no significant HFSE anomalies, suggesting a garnet-bearing enriched peridotite source. Primitive mantle-normalized patterns of the high-K alkali-calcic to talc-alkaline suite include more fractionated felsic types and display Nb-Ta negative anomalies, suggesting another source with amphibole - garnet in the residue and possible origin of felsic rocks by partial melting of mafic lower crust with garnet and titanite-rutile in the residue. In leucogabbro, fairly low Sri (0.70538) and little negative eNd(750 Ma) ( + 0.2), with a TDM single-stage Nd model age of 1.42 Ga, are consistent with magmas extracted near the lithosphere - asthenosphere boundary from an enriched mantle source close to BSE (Bulk Silicate Earth). In monzodiorite, little higher Sri (0.70628) and strongly negative eNd (560 Ma) ( - 8.8), with a TDM single-stage Nd model age of 1.64 Ga, point to a supplementary (lithospheric?) mantle source metasomatized by subduction products. HMPC and GS massifs, emplaced in a syn-to post-kinematic environment after the major collision stage, illustrate coeval magnesian tholeiitic and magnesian high-K alkali-calcic talc-alkaline (I-type) igneous suites, in which primary magmas were tapped from different mantle sources, followed by younger felsic suite issued from garnet-bearing lower crustal source.
机译：在喀麦隆泛非造山带中，西喀麦隆地区（WCD）的特征是明显缺乏太古宙古古生界遗迹，新元古代盆地的发育和丰富的深部岩层。 Hossere Mana岩体复合体（HMPC）和Gapi辉长岩储层位于白垩纪Ngaou Boh花岗岩复合体和新近纪Tchabal Gangbada basanite-trachyte-rhyolite火山高原附近。它们包括斜辉石+角闪石+/-橄榄石白云母，斜辉石+斜闪石辉石辉石，黑云母+斜闪石+/-斜石辉石辉闪石，斑岩和叶状黑云母+/-白云母辉石。镁钴矿（0.66-0.61）辉石（0.57-0.37）和辉闪石（0.66-0.55）-辉锰矿（0.47-0.33）表现出两个平行的Mg＃趋势，证明了两个对比的火成岩组，镁质生硬质岩和镁质高强度岩浆。碱金属至滑石碱性（I型）的K。原始的地幔归一化模式为零散的，没有明显的HFSE异常，表明富含石榴石的橄榄岩来源。从高钾碱钙到滑石碱性套件的原始地幔归一化模式包括更多的分形长英质类型，并显示出Nb-Ta负异常，这表明另一种含闪石的来源-残渣中的石榴石和部分熔融可能的长英质岩石起源残渣中含有铁石榴石和钛红土-金红石的镁铁质下壳。在白带中，相当低的Sri（0.70538）和极小的负eNd（750 Ma）（+ 0.2），TDM单阶段Nd模型年龄为1.42 Ga，与岩石圈附近的岩浆-富集地幔的软流圈边界相一致。源接近BSE（散装硅酸盐土）。在单闪闪岩中，稍高的Sri（0.70628）和强负eNd（560 Ma）（-8.8），TDM单阶段Nd模型年龄为1.64 Ga，表明由俯冲产物交代的补充地幔源。 HMPC和GS地块位于主要碰撞阶段之后的运动到后运动环境中，它们说明了中世纪的镁质生硬质和镁质高K碱度滑石碱（I型）火成岩套件，其中利用了初级岩浆。来自不同的地幔来源，其次是来自带有石榴石的下地壳来源的年轻的长英质套件。

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