Petrogenesis and Tectonic Significance of Meta-Mafic Rocks from Eastern Mayo Kebbi Massif (Pala), Chad: Evidence for a Depleted Mantle Source and Intra-Oceanic Subduction — Oak Academic Publishing
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Petrogenesis and Tectonic Significance of Meta-Mafic Rocks from Eastern Mayo Kebbi Massif (Pala), Chad: Evidence for a Depleted Mantle Source and Intra-Oceanic Subduction
Department of Mining, New and Renewable Energies. National Higher Institute of the Sahara and Sahel, Iriba, Chad
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Department of Mining and Geological Engineering, Faculty of Life and Earth Sciences, Pala University, Pala, Chad
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Department of Mining and Geological Engineering, Faculty of Life and Earth Sciences, Pala University, Pala, Chad
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Department of Geology, Faculty of Sciences and Techniques, University Adam Barka of Abeché, Abeché, Chad
1 Department of Mining, New and Renewable Energies. National Higher Institute of the Sahara and Sahel, Iriba, Chad
2 Department of Mining and Geological Engineering, Faculty of Life and Earth Sciences, Pala University, Pala, Chad
3 Department of Mining and Geological Engineering, Faculty of Life and Earth Sciences, Pala University, Pala, Chad
4 Department of Geology, Faculty of Sciences and Techniques, University Adam Barka of Abeché, Abeché, Chad
Meta-mafic rocks from the eastern Mayo Kebbi massif (Pala area, Chad) provide new insights into the geodynamic evolution of the Central African Orogenic Belt (CAOB). Petrographic and geochemical analyses reveal that the meta-mafic rocks consist of amphibolites and métagabbros, derived from a basalts protolith. These rocks exhibit calc-alkaline to tholeiitic affinities and are characterized by granoblastic and microlitic porphyritic textures. Enrichment in light rare earth elements (LREE), parallel REE patterns, and systematic variations in major and trace elements indicate that fractional crystallization was the dominant differentiation process. These rocks formed in a primitive arc magmatic setting, with source components including N-MORB-type and depleted mantle. Discrimination diagrams (e.g., V/Ti vs. Zr, Th/Yb vs. Nb/Yb) indicate an intra-oceanic subduction influence, supported by negative anomalies in Nb-Ta, Zr-Hf and Ti. These findings support a tectonic model involving an active margin between a mid-ocean ridge and an intra-oceanic arc, reflecting the closure or subduction of an ancient oceanic domain.
KeywordsMeta-Mafic RocksMayo KebbiN-MORBDepleted MantleCentral African Orogenic Belt
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