Granitoids of the Magba Shear Zone, West Cameroon, Central Africa: Evidences for Emplacement under Transpressive Tectonic Regime

Ntieche, Benjamin; Mohan, M. Ram; Moundi, Amidou

doi:10.1007/s12594-017-0556-4

Cited by 22 publications

(9 citation statements)

References 48 publications

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“…The basement rocks consist of Paleoproterozoic gneisses and amphibolites of metaigneous and meta-sedimentary origin [17,18]. The granitoids of the Adamawa-Yade domain are classified as syn-, late and post-tectonic [10,[18][19][20]. Structurally, the basement rocks of the Adamawa Yade domain has undergone four phases of deformation (D1 to D4); each phase being characterized by plane linear and plano-linear structures [20,21].…”

Section: Regional Geological Frameworkmentioning

confidence: 99%

“…The granitoids of the Adamawa-Yade domain are classified as syn-, late and post-tectonic [10,[18][19][20]. Structurally, the basement rocks of the Adamawa Yade domain has undergone four phases of deformation (D1 to D4); each phase being characterized by plane linear and plano-linear structures [20,21]. The granitoids emplacement has been favored by the replay of the Central Cameroon Shear Zone [22][23][24][25].…”

Section: Regional Geological Frameworkmentioning

confidence: 99%

“…The granitoids emplacement has been favored by the replay of the Central Cameroon Shear Zone [22][23][24][25]. The granitoids from the Tikar Plain are associated in places to few mafic to intermediate dykes outcrops [20] (Fig. 3) that are not yet been studied in detail.…”

Section: Regional Geological Frameworkmentioning

confidence: 99%

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Petrochemical constrains on the origin and tectonic setting of mafic to intermediate dykes from Tikar plain, Central Cameroon Shear Zone

et al. 2021

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The Tikar plain is located on the Cameroon Central Shear Zone. It is also part of the North Equatorial Pan-African Belt. It is formed of granitoids intruded in places by mafic and intermediate dykes. The mafic dykes are essentially banded gabbros composed of plagioclases, pyroxenes, amphiboles, biotites and opaques. Their textures range from porphyroblastic to porphyritic. The intermediate dykes are monzonites and monzodiorites and are characterized, respectively, by cataclastic and mylonitic textures. The minerals identified are amphiboles, potassium feldspar, pyroxenes, epidotes, sphenes and opaques. Seritization reaction is mostly present on the mafic and intermediate dykes, while chloritization is much more pronounced on the intermediate dykes. The Tikar plain dykes are high-k calc-alkaline to shoshonitic. They are characterized by low to moderate SiO2 content (42.08–61.96 wt%), low to high TiO2 (0.47–2 wt%) and low Ni (1.48–99.18 ppm) contents. The mafic dykes show fractional trends with negative anomalies of Zr, U and P and positive Rb, Ba, Ta, Pb and Sr in multi-element diagrams, while the intermediate dykes present negative anomalies of Nb, Ta, Zr, Sr P and Ti and relative positive anomalies of Rb, Ba and Pb. The rare-earth elements (REE) patterns show positive Eu anomalies for the mafic dykes and negative anomalies for the intermediate dykes. The REE spectrum of all the dykes shows enrichment in LREE with relatively flat HREE, which can indicate arc magmatism. In the Zr–Ti/100–Sr/2 diagram, the mafic dykes plot in the island arc tholeiite and calc-alkaline basalt fields. The Th, Nb and LREE concentrations indicate that the subducted lithosphere with crustal component contributed to generation of the intermediate dykes of the Tikar plain. The geochemical characteristics of the mafic to intermediate dykes suggest their derivation from a various degree of partial melting in the garnet spinel facies, probably between depths of 80 and 100 km. The collision between the Central African Fold Belt and the northern edge of the Congo craton resulting in crustal thickening, sub-crustal lithospheric delamination and upwelling of the asthenosphere may have been the principal process in the generation of the intermediate dykes in the Tikar plain. The magma for the mafic and intermediate dyke would have migrated through the faults network of the Central Cameroon Shear Zone before crystallizing in the granito-gneissic basement rocks.

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Section: Regional Geological Frameworkmentioning

confidence: 99%

Section: Regional Geological Frameworkmentioning

confidence: 99%

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Petrochemical constrains on the origin and tectonic setting of mafic to intermediate dykes from Tikar plain, Central Cameroon Shear Zone

et al. 2021

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“…1a), running through Cameroon across the Atlantic Ocean into northeast of Brazil [20][21][22][23][24][25]. The central domain of CAFB in Cameroon comprises the Paleoproterozoic granulite [18,[26][27][28] and the Neoproterozoic metasedimentary rocks [29][30][31] intruded by syntectonic granitoids [25,[32][33][34][35][36][37][38][39] along thrust and shear zones ( Fig. 1b), the most prominent being the Central Cameroon Shear Zone (CCSZ).…”

Section: Regional Geological Settingmentioning

confidence: 99%

Assessment of shear zone-derived quartz from the Etam area, southwest Cameroon as potential high-purity quartz resource: petrography, geochemistry and technological studies

et al. 2020

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This study focuses on the evaluation of the high-purity quartz (HPQ) potential of a shear zone-hosted hydrothermal and metamorphic quartz deposit in Etam, southwest Cameroon. The shear zone quartz-rich rock is monomineralic and consists of both milky and translucent varieties. The combination of ICP-MS and LA-ICP-MS analytical techniques was used to assess the chemical purity of both quartz varieties. These compositional analyses show that all quartz samples have SiO 2 content of 98.46-99.75 wt% with very low concentrations of all the other elements. Translucent quartz when compared to the milky quartz variety shows low concentration of most of the elements including the following principal impurities: Al (mean 107 µg g −1 ), Ca (mean 27.85 µg g −1 ) and Fe (mean 26.05 µg g −1 ). Bubble generation in the samples after flame fusion over a silica plate was assessed to test the suitability of the quartz in industrial uses. The results obtained from the chemical analyses and bubble formation tests indicate that all the samples investigated do not meet the HPQ requirement. However, the translucent quartz shows characteristics of medium-purity quartz and can produce silica glass for some industrial manufacturing even without further purification. In this study, the fluid inclusions in the samples were examined as this bears information on the economic viability of the deposit and provides clues on the genesis of the quartz vein. Also tiny mineral inclusions within individual quartz grains were identified by SEM-EDS. The results of these studies show that the deposit is probably of metamorphic origin marked by crystal-plastic deformation in quartz grains. The veins were later modified by hydrothermal fluid input. The results also indicate that the majority of impurities are likely hosted by fluid inclusions and thus the quartz can be upgraded to HPQ after purification by suitable methods.

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“…Three main tectonic deformational phases are generally recorded in the Central Pan-African Fold belt in Cameroon [38]- [46]: (1) a Compressive deformational phase D1 whose main markers are NNW-SSE to NW-SE foliation; (2) an early left-lateral deformational phase D2 characterized by anticlockwise rotation and NE-SW sinistral transposition of early structures, and (3) a NE-SW late right-lateral deformational phase D3 marked by a clockwise rotation and a dextral transposition of preexisting structures [35]. However, recent research works from [47] and [35] described a late sinistral shear phase transposing NE-SW dextral D3-related structures, suggesting a more complex deformation history for the Pan-African Belt in Cameroon. The NW-SE foliation recorded by gneiss corresponds to the S1, thus a D1-related structure during the compressive tectonic.…”

Section: B Contribution To Pan-african Tectonic Evolutionmentioning

confidence: 99%

Structural Interpretation of Lineament from Nlonako Area and Surroundings: Contribution to Pan-African Tectonic Reconstruction

Kamgang

Kouémo

Fozing

et al. 2020

EJGEO

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The Nlonako anorogenic complex (NAC) is located in the south western part of the Cameroon Line and is superposed on the N50E section of the central Cameroon shear zone. It is suggested to be a ring complex of 10 km diameter which was emplaced as sill intrusive body during the Tertiary. In order to do characterize the Nlonako complex shape and characterize the tectonic history in the study area and surrounding, spatial technology (Landsat 8 ETM+ and SRTM images) were used for geological mapping and structural reconstruction based on lineament analysis. Data extracted from Landsat 8 ETM and SRTM images show a sub-circular shape for the NAC and the superposition of field and petrographic data from our previous research works confirm the fact that the NAC is a ring or annular complex slightly elongated NNE-SSW, thus it is known as the Nlonako ring complex (NRC). Map of lineament synthesis and the SRTM image of the study area display NE-SW, NW-SE and N-S trend structures. (1) The dominant NE-SW trend mostly displayed by the NRC and its basement rock is parallel to (i) the main metamorphic foliation trend and (ii) to the central Cameroon shear zone regional fault, corresponds to the trending of the regional foliation, structures and the Ngondo pluton elongated shape. (2) The secondary N-S direction may correspond to the late deformational phase in the area because, the N-S-related structures transposing NE-SW structures towards a meridional direction in the NRC basement rock. (3) The NW-SE trend corresponds to the direction of NW-SE fault cross cutting the NRC. Field data and synthetic lineament map enable to identify: (1) a Compressive deformational phase D1 whose main markers are NNW-SSE to NW-SE S1 foliation; (2) an early left-lateral deformational phase D2 characterized by anticlockwise rotation of clasts and NE-SW sinistral transposition of early structures; (3) a NE-SW right-lateral deformational phase D3 marked by clockwise rotation and dextral transposition of preexisting structures as well as the NE-SW S3 foliation and (4) a late left-lateral deformational phase D4 marked by the N-S transposition of NE-SW dextral D3-related structures by late sinistral shear movement. This suggests a more complex tectonic history for the Pan-African Belt in Cameroon showing at least three shear phases, that is a right-lateral phase, sandwich by two left-lateral phases.

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Granitoids of the Magba Shear Zone, West Cameroon, Central Africa: Evidences for Emplacement under Transpressive Tectonic Regime

Cited by 22 publications

References 48 publications

Petrochemical constrains on the origin and tectonic setting of mafic to intermediate dykes from Tikar plain, Central Cameroon Shear Zone

Petrochemical constrains on the origin and tectonic setting of mafic to intermediate dykes from Tikar plain, Central Cameroon Shear Zone

Assessment of shear zone-derived quartz from the Etam area, southwest Cameroon as potential high-purity quartz resource: petrography, geochemistry and technological studies

Structural Interpretation of Lineament from Nlonako Area and Surroundings: Contribution to Pan-African Tectonic Reconstruction

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