Petrology of volcano-sedimentary deposits from Mayo Mbota, west of the Cretaceous Babouri-Figuil basin, North Cameroon.

The investigation of volcano-sedimentary rocks situated to the west of the Cretaceous Babouri-Figuil basin involved a comprehensive characterization encompassing petrography, mineralogy, and geochemistry. The sedimentary formations were classified into four distinct facies: coarse sandstones, medium sandstones, fine sandstones, and schistose marls. Additionally, post-sedimentary lava flows composed of andesitic basalts were identified. Petrographic analysis revealed quartz as the predominant constituent in the sedimentary rocks. The volcanic rocks exhibited two distinct textures: a microlitic porphyritic texture, featuring oxides, plagioclase phenocrysts, and clinopyroxenes, and a doleritic porphyritic texture, wherein the rock volume comprised 10–15% automorphic plagioclase phenocrysts (1 to 3.6 mm), 20% clinopyroxenes (1.5 mm), 2–7% oxide crystals (less than 1 mm), 2% olivines, and approximately 1% amphibole phenocrysts (> 1 mm). The identified mineral phases were categorized into two groups: primary minerals (calcite, feldspar, quartz, muscovite) and secondary minerals (kaolinite, illite, smectite), along with titanium oxides, anatase, hydrated sodium silicates, and analcime. Geochemical analysis of the basalts indicated their classification as oceanic tholeiites, suggesting a composition of andesitic basalts emplaced within an orogenic setting. The Mayo Mbota sediments were categorized as intermediate to acidic rocks associated with active continental margins, deposited in an arid to semi-arid environment. These sediments were derived from the accumulation of alteration products of felsic rocks. [ABSTRACT FROM AUTHOR]