Evaluation of the mineralizing potential of the Mbengwi plutonics, Northwestern Cameroon, Central Africa
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ORIGINAL PAPER
Evaluation of the mineralizing potential of the Mbengwi plutonics, Northwestern Cameroon, Central Africa Benoît Joseph Mbassa 1 & Emmanuel Njonfang 2 & Michel Grégoire 3 & Zénon Itiga 1 & Pierre Kamgang 4 & Mathieu Benoit 3 & Paul Désiré Ndjigui 4 & Caroline Neh Ngwa 1 & Junior Désiré Nolla 5 Received: 14 November 2017 / Accepted: 18 October 2018 / Published online: 30 October 2018 # Saudi Society for Geosciences 2018
Abstract The Mbengwi area consists of Cenozoic alkaline rocks and Pan-African calc-alkaline plutonics. The alkaline magmatic series include volcanics (basanites, hawaiites, mugearite, and rhyolite) and syenites while the calc-alkaline plutonics comprise various granitoids (granites, granodiorites, quartz monzonites, and monzonites) associated with monzodiorites. These plutonics are calcalkaline, metaluminous to weakly peraluminous, mostly I-type, displaying high potassic to shoshonitic affinities. Their magmas are relatively evolved and typically result from melting of the lower continental crust with variable involvement of the oceanic crust. According to the ranges of their Rb/Sr, Zr/Hf, and K/Rb ratios, these magmas have mostly not undergone post-magmatic hydrothermal activity which would lead to mineralization. With regard to their contents in certain elements such as Sr, Rb, and Ba in addition to their gradient in Sm/Eu and Rb/Ba ratios, the Mbengwi plutonics are typical of granitoids devoid of U and Ta deposits. They are also barren in Sn, W, and Mo but mostly productive regarding Cu, Zn, and Fe (Au) skarn. Keywords Cameroon . Central Africa . Pan-African . Calc-alkaline plutonics . Mineralizing potential
Introduction Determining the mineralizing potential of intrusive bodies is important because every specific type of granite is usually accompanied with a specific type of ore deposit. Numerous precious metal deposits are spatially, temporally, and genetically associated to various types of granitic rocks (Eugster
* Benoît Joseph Mbassa [email protected] 1
Institute of Geological and Mining Research (IRGM), Branch for Volcanological and Geophysical Research (ARGV), P.O. Box 370, Buea, Cameroon
2
Laboratory of Geology, Higher Teacher Training College, University of Yaoundé I, P.O. Box 47, Yaoundé, Cameroon
3
Géosciences–Environnement–Toulouse, UMR 5563, Observatoire Midi Pyrénées, Université Paul-Sabatier, 14, avenue Édouard-Belin, 31400 Toulouse, France
4
Department of Earth Sciences, Faculty of Sciences, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon
5
Institute of Geological and Mining Research, P.O. Box 4110, Yaoundé, Cameroon
1985; Sillitoe 1996). It had been proved that most Sn, W and several rare metal (Ta, Nb, Li, Be, Zr, Ga, REE) deposits, above 60% of Cu resources, approximately 10% of Fe, Au, Zn, Pb, Ag and U, in addition to many minor metals (Bi, Cd, Sb, Te, Re, In, Sc) are related to granitic rocks (Sillitoe 1996). Furthermore, Ghodsi et al. (2016) found that, calc-alkaline Itype magmas have a high ability to bear and concentrate base metals
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