Evidence of heterogeneous crustal origin for the Pan-African Mbengwi granitoids and the associated mafic intrusions (northwestern Cameroon, central Africa)

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• 作者：Benoî ; t Joseph Mbassa^a ; ^{benjo_mbassa@yahoo.fr" class="auth_mail" title="E-mail the corresponding author} ; Pierre Kamgang^b ; Michel Gré ; goire^c ; Emmanuel Njonfang^d ; Mathieu Benoit^c ; Zé ; non Itiga^a ; Sté ; phanie Duchene^c ; Moï ; se Bessong^e ; Pauline Wonkwenmendam Nguet^a ; Ntepe Nfomou^a
• 关键词：High-K calc&ndash ; alkaline plutonics ; Metaluminous to weakly peraluminous ; Type I ; Lower continental crust ; Subduction signature ; Cameroon
• 刊名：Comptes Rendus Geoscience
• 出版年：2016
• 出版时间：February-March 2016
• 年：2016
• 卷：348
• 期：2
• 页码：116-126
• 全文大小：2743 K

文摘

The Mbengwi plutonics consist of intermediate to felsic granitoids forming a continuous magmatic series from monzonite to granite and mafic intrusions. Their mineralogical composition consists of quartz, plagioclases, K-feldspars, biotite, muscovite, and amphibole. The accessory phase includes opaque minerals + titanite ± apatite ± zircon, while secondary minerals are pyrite, phengite, chlorite, epidote, and rarely calcite. These plutonics are assigned high–K calc–alkaline to shoshonitic series, metaluminous to weakly peraluminous and mostly belong to an I–type suite (A/CNK = 0.63–1.2). They are typically post–collisional, with a subduction signature probably being inherited from their protoliths emplaced during the subduction phase. The Sr and Nd isotopic data evidence that these plutonics result from melting of the lower continental crust with variable contribution of the oceanic crust. Their geochemical features are similar to those of western Cameroon granitoids related to the Pan–African D₁ event in Cameroon.