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<p>This paper present field observations, petrology, and geochemical data to discuss the petrogenesis of the Bangoua basalts. The study area is located in the southern end of the Cameroon Volcanic Line within the Central PanAfrican Fold Belt. The rocks display fine to coarse-grained sizes, indicative of several crystallization phases. The geochemical data show non-dispersion, indicating a unique magmatic series. The samples are classified as transitional basalts with a tholeiitic affinity, and a sodic basaltic trachyandesite composition, belonging to the medium-K calc-alkaline series. These rocks evolved from the alkaline to transitional mafic magmas through crystal fractionation. The significant Sr anomaly observed in the primitive normalized Rare Earth Elements (REE), despite of none clear Eu anomaly, indicates plagioclase fractional crystallization. Geochemical analysis revealed that they were subject to medium - to - high crustal contamination. The Bangoua transitional basalts were formed through the partial melting of a mantle source at various depths, indicating a melting degree of around 4–5%. This process occurred at an approximative depth of around 100&#xa0;km between 2 and 4 GPa, suggesting a partial melting of a garnet peridotite source at around 14–16%. Their magma was generated in an enriched primordial deep mantle source in the crustally contaminated lithospheric mantle, and Oceanic Island Basalts (OIB) fields within the Proterozoic oceanic plateau basalts, which were metasomatized by subduction processes. Mantle plume-derived basalts occur in both oceanic and continental settings; the worldwide continental volcanic series are linked to the mantle plumes. The samples plot in Enriched Mantled (EM) source, mainly EM1 - OIB like indicating that the emplacement of the Bangoua basalts were probably formed by the partial melting of a metasomatized subcontinental lithospheric mantle, followed by lithospheric thinning and rapid emplacement.</p>

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Petrochemical characterization of transitional tholeiitic basalts in Bangoua area (West Cameroon), Southern part of the Cameroon Volcanic Line

  • 期刊论文

  • 发表日期：

    2026年1月16日

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  • Pascal Simo,
  • Brice Kamguia Woguia,
  • Pierre Wotchoko,
  • Joëlle Flore Tene Djoukam,
  • Gus Djibril Kouankap Nono

摘要

This paper present field observations, petrology, and geochemical data to discuss the petrogenesis of the Bangoua basalts. The study area is located in the southern end of the Cameroon Volcanic Line within the Central PanAfrican Fold Belt. The rocks display fine to coarse-grained sizes, indicative of several crystallization phases. The geochemical data show non-dispersion, indicating a unique magmatic series. The samples are classified as transitional basalts with a tholeiitic affinity, and a sodic basaltic trachyandesite composition, belonging to the medium-K calc-alkaline series. These rocks evolved from the alkaline to transitional mafic magmas through crystal fractionation. The significant Sr anomaly observed in the primitive normalized Rare Earth Elements (REE), despite of none clear Eu anomaly, indicates plagioclase fractional crystallization. Geochemical analysis revealed that they were subject to medium - to - high crustal contamination. The Bangoua transitional basalts were formed through the partial melting of a mantle source at various depths, indicating a melting degree of around 4–5%. This process occurred at an approximative depth of around 100 km between 2 and 4 GPa, suggesting a partial melting of a garnet peridotite source at around 14–16%. Their magma was generated in an enriched primordial deep mantle source in the crustally contaminated lithospheric mantle, and Oceanic Island Basalts (OIB) fields within the Proterozoic oceanic plateau basalts, which were metasomatized by subduction processes. Mantle plume-derived basalts occur in both oceanic and continental settings; the worldwide continental volcanic series are linked to the mantle plumes. The samples plot in Enriched Mantled (EM) source, mainly EM1 - OIB like indicating that the emplacement of the Bangoua basalts were probably formed by the partial melting of a metasomatized subcontinental lithospheric mantle, followed by lithospheric thinning and rapid emplacement.