Petrochemical characterization of metasedimentary rocks in the Nkolkosse area, Yaoundé domain of the Pan-African fold belt in Cameroon: constrain on their provenance, protolith, and tectonic setting.

Autor: Armelle, Ntoussi Foka, Djibril, Kouankap Nono Gus, Brice, Kamguia Woguia, Timoleon, Ngnotue
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Zdroj: Arabian Journal of Geosciences; Dec2023, Vol. 16 Issue 12, p1-24, 24p
Abstrakt: The undocumented Nkolkosse area belongs to the southern domain of the Pan African Fold Belt in Cameroon. Petrography and whole rock geochemistry reveal that the area is made up mainly of medium-grade gneiss of amphibolite facies. The mineral association in rock is quartz + potassic feldspar + plagioclase + biotite + muscovite ± rutile ± zircon ± opaque minerals. Their SiO2 contents are very high, varying from 76.37 to 80%, while the concentrations of Al2O3 are low (9.61–11.08%) and very low for CaO (< 1%). The average value of K2O/Na2O ratios is greater than 1 (1.40). All these characteristics point to metasedimentary rocks as revealed by the binary diagram TiO2 vs. SiO2, in which all the samples plot in the field of paragneiss. The inferred protoliths of Nkolkosse metasedimentary rocks yield the composition of arkoses and lithic arenites. These protoliths are from mature to immature sediments, resulting from chemical weathering of a felsic source and have experienced a high degree of sedimentary recycling, which supports the recycled nature of those meta-sediments with little contribution from igneous rocks. The protoliths of the Nkolkosse gneiss are from the upper continental crust and were deposited in a passive to active continental margin, within a subduction tectonic setting. These results are concomitant with other results described in the Central African Fold Belt in Cameroon, Brazil, and the northwestern edge of the Congo craton, inferring that they were forming a single block. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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