Geochemistry and ⁴⁰ar/³⁹ar Geochronology of Amphibolites from Banefo-Mvoutsaha Area, Central Domain of the Pan-African Fold Belt in Cameroon

MVODO Hermine¹, NGA ESSOMBA TSOUNGUI Philomène Estelle², KOUANKAP NONO Gus Djibril^3, , KAMGUIA WOGUIA Brice⁴ and SIMO Pascal⁴

¹Departement of Geosciences and Environnement, University of Ebolowa, P.O.Box 118 Ebolowa, Cameroon

²Department of Mining Engineering and Mineral Processing, National Advanced School of Mines and Petroleum Industries, University of Maroua, P.O.Box 46 Maroua, Cameroon

³Department of Geology, HTTC, University of Bamenda, P.O.Box 39 Bambili; Bamenda, Cameroon

⁴Laboratory of Petrology and Structural Geology, University of Yaoundé I, PO Box 3412 Messa-Yaoundé, Cameroon

Cite this paper:
MVODO Hermine, NGA ESSOMBA TSOUNGUI Philomène Estelle, KOUANKAP NONO Gus Djibril, KAMGUIA WOGUIA Brice and SIMO Pascal. Geochemistry and ⁴⁰ar/³⁹ar Geochronology of Amphibolites from Banefo-Mvoutsaha Area, Central Domain of the Pan-African Fold Belt in Cameroon. Journal of Geosciences and Geomatics. 2025; 13(2):31-43. doi: 10.12691/jgg-13-2-1

Abstract

The Banefo-Mvoutsaha area lies along the Central Cameroon Shear Zone and belongs to the Central Domain of the Pan-African Fold Belt in Cameroon. The amphibolites of the study area are of two types: The banded amphibolites which are associated with migmatites and composed of Hbl + Bt + Qtz + Kfs + Pl ± Grt + Op; and the massive amphibolites which outcrops as discontinuous bands within the garnet bearing-gneisses; its mineral assemblage is made up of Hbl + Qtz + Kfs ± Grt ± Op. The studied amphibolites are ortho-derived, their SiO₂ contents range from 48 to 52 wt%, they are enriched in LREEs and LILEs relatively to HREE, and display negative Eu anomalies (0.65 ≤ Eu/Eu* ≤ 0.96), characteristics of alkali basaltic rocks, which belong to intraplate tholeiitic series. The banded amphibolites samples yield an Ar-Ar age of 618.14 ± 11.43 Ma, while the massive amphibolites samples ages are 547.50 ± 3.15 Ma. The 618 Ma age coincide with the emplacement age of granitoids that intruded the metamorphic basement of the area. The age of 547.50 ± 3.15 Ma is correlated to amphibolitic metamorphism events that mark the end of the Pan-African orogeny in the study area. These new Ar-Ar ages therefore point out at least two phases of amphibolitic metamorphism in the Central domain of the Pan-African Fold Belt in Cameroon.

Keywords:
Pan-African Amphibolite Tholeiites series Intraplate basalts Argon-Argon

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