Mineralogy, geochemistry and petrogenesis of the recent magmatic formations from Mbengwi, a continental sector of the Cameroon Volcanic Line (CVL), Central Africa

Mbassa, Benoît Joseph; Njonfang, Emmanuel; Benoît, Mathieu; Kamgang, Pierre; Grégoire, Marilaure; Duchêne, Stéphanie; Brunet, Pierre; Ateba, Bekoa; Tchoua, Félix M.

doi:10.1007/s00710-012-0227-5

Cited by 19 publications

(8 citation statements)

References 51 publications

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“…However, high degree of fractional crystallization is expected to elevate the alkalinity of the residual melts, since olivine, pyroxene, and feldspar have lower Na and K contents than the residual melt (Scaillet & Macdonald, 2003). As the basalts in TLIP characteristically display high alkali contents and sodic affinity (Figure 6), the evolutionary products after protracted fractional crystallization tend to be peralkaline (trachyte, phonolite, and pantellerite) in contrast to low alkali rhyolite in the TLIP (e.g., Barberi et al, 1975;Civetta et al, 1998;Mbassa et al, 2012;Novak & Mahood, 1986;Peccerillo et al, 2003Peccerillo et al, , 2007Smith et al, 1977;White et al, 2012). Hence, significant crustal contamination combined with crystal fractionation of alkali feldspar is expected to occur during the magma evolution leading to a peralkaline to subalkaline transition.…”

Section: 1029/2019jb018382mentioning

confidence: 99%

Petrogenesis of Transitional Large Igneous Province: Insights From Bimodal Volcanic Suite in the Tarim Large Igneous Province

et al. 2020

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The Tarim large igneous province (TLIP) corresponds to a transitional large igneous province based on the high proportion of felsic rocks, classifying between mafic and silicic large igneous provinces. Here we investigate a bimodal suite including trachydacite, rhyolite, and basanite from the Northern Tarim Uplift using petrological, geochemical, stable, and radiogenic isotopic techniques with a view to understand the formation of the TLIP. Our study reveals a multistage origin involving multiple components, although the various rock suites are genetically linked and formed under a rift incubation setting related to mantle plume. The low δ26 Mg values (−0.48‰ to −0.71‰), Fe/Mn > 60, FC3MS (FeOT/CaO‐3*MgO/SiO2) > 0.65, and high TiO2 contents (4.45–4.93 wt.%) of basanite from this suite suggest formation through partial melting of carbonated eclogite formed by recycled oceanic crust. The thick lithosphere beneath the Tarim Craton promoted extensive interaction between the underplated basaltic magmas and crust‐derived magmas leading to the formation of multistage magma chambers. Geochemical and mineralogical studies suggest that the trachydacite experienced a mixing, assimilation, storage, and hybridization process, whereas the rhyolite was produced by fractional crystallization from the associated mantle‐derived magma with significant crustal contamination. The abundance of amphibole in the trachydacite suggests a hydrous parental magma with H2O content in the range of 2.75 to 4.05 wt.%. Our results suggest that hydrous crustal components contributed significantly in the formation of voluminous felsic rocks of the TLIP.

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Section: 1029/2019jb018382mentioning

confidence: 99%

Petrogenesis of Transitional Large Igneous Province: Insights From Bimodal Volcanic Suite in the Tarim Large Igneous Province

et al. 2020

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“…Structurally, the Pan African Orogeny in Cameroon is divided into the Northwestern Cameroon Domain (NWC), the Adamawa-Yade Domain (AYD) and the Yaounde Domain (YD) with the Central Cameroon Shear Zone being its main lineament ( Fig. 2a; Toteu et al 2004;Mbassa et al 2012). The Northwestern Cameroon Domain (NWC) consists of Mt.…”

Section: Geological Setting Of Study Areamentioning

confidence: 99%

Gemstones-bearing sediments in the Mbiame floodplain, northwestern Cameroon

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Vishiti

et al. 2020

J. Sediment. Environ.

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Sediment samples obtained from pits in the Mbiame floodplain gemstone prospect in the northwestern part of Cameroon were studied for their bulk geochemical properties together with the mineral composition of the gemstones found therein to decipher their provenance. Five main layers were isolated in each pit comprising an organic rich humus layer, muddy layer, unconsolidated and poorly sorted sandy layer, clay layer and gravel layer. The gravel layer is the most high-yielding in terms of gemstones content. The sediments have high rare earth element (REE) concentrations varying between 135 and 456 ppm with variable light/heavy rare earth element (LREE/HREE) ratio values (5.8-21.5). REE chondrite normalized patterns show similar high LREE enrichment and no Eu anomalies (Eu/Eu* = 0.9 − ~ 1) for all samples. The gemstones selected from the various horizons range in color from light gray, light blue/green, dark blue, pale brown and red. Some of the grains have zircon and ilmenite mineral inclusions while some of the zoned grains show simple core-rim zonation as well as oscillatory and sectorial zoning patterns. Bulk sediment geochemistry of sediments from the Mbiame gem prospect suggests an igneous provenance generally of felsic intermediate source input. The alluvial gemstones from the Mbiame gem prospect are the sapphire variety of corundum and the grains combined with zircon and ilmenite inclusions and megacrysts suggest a derivation from felsic to intermediate igneous rocks.

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“…1c). The Cenozoic bimodal alkaline magmatic series consist of lavas and syenites belonging to the same magmatic episode (Mbassa et al 2012). The composition of volcanic rocks ranges from basanite to rhyolite, with a gap between 50 and 62 wt.% SiO 2 .…”

Section: Geological Settingmentioning

confidence: 99%

“…The composition of volcanic rocks ranges from basanite to rhyolite, with a gap between 50 and 62 wt.% SiO 2 . Mafic lavas display OIB features and HIMU mantle isotopic signature (Mbassa et al 2012). The Pan-African plutonics consist of monzodiorites and a continuous granitic series extending from monzonites to granites.…”

Section: Geological Settingmentioning

confidence: 99%

Evaluation of the mineralizing potential of the Mbengwi plutonics, Northwestern Cameroon, Central Africa

et al. 2018

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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.

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Mineralogy, geochemistry and petrogenesis of the recent magmatic formations from Mbengwi, a continental sector of the Cameroon Volcanic Line (CVL), Central Africa

Cited by 19 publications

References 51 publications

Petrogenesis of Transitional Large Igneous Province: Insights From Bimodal Volcanic Suite in the Tarim Large Igneous Province

Petrogenesis of Transitional Large Igneous Province: Insights From Bimodal Volcanic Suite in the Tarim Large Igneous Province

Gemstones-bearing sediments in the Mbiame floodplain, northwestern Cameroon

Evaluation of the mineralizing potential of the Mbengwi plutonics, Northwestern Cameroon, Central Africa

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