Geology, mineralogy and geochemistry of the Kekem dyke swarm (Western Cameroon): Insights into Paleozoic–Mesozoic magmatism and geodynamic implications

• Published in: Comptes rendus. Geoscience Vol. 349; no. 4; pp. 175 - 185
• Main Authors: Tchaptchet, Depesquidoux Tchato, Wambo, Nicole Armelle Simeni, Kouamo, Noël Aimé Keutchafo, Tchouankoué, Jean-Pierre, Cucciniello, Ciro
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.07.2017; Académie des Sciences. Institut de France
• Subjects: Basement control; Dyke swarm; Magma; Marine; Mesozoic; Palaeozoic; Rifting; Spinel mantle source; Tectonics; Tholeiitic basalt; Tholeiitic/transitional basalts; Volcanic rocks; Western Gondwana; ASE, Mauritania, North Gondwana; Tholeiitic/transitional basalts; Basement control; Rifting; Western Gondwana; Dyke swarm; Spinel mantle source
• ISSN: 1631-0713; 1778-7025; 1778-7025
• DOI: 10.1016/j.crte.2017.02.005

The broadly N70°–90°E-trending dykes swarm at Kekem cut across the Paleoproterozoic-to-Achean terranes of West Cameroon remobilized during the Pan-African orogeny. They are picrite basalts and basalts with tholeiitic/transitional affinity, as shown by mineralogical and geochemical data, with variable major and trace element contents, MgO ranges from 7.3 to 12.4wt.%, Cr from 190 to 411ppm, Ni from 15 to 234ppm. All the dykes are light REE enriched with LaN/YbN values of 5.3–8.1, suggesting a co-magmatic origin. They originated from a 2.8% partial melting of a spinel-mantle source with no or little crustal input. The geochemical features of Kekem dykes are similar to those of Paleozoic and Mesozoic dykes recorded in North and Central Africa, suggesting multiple reactivations of pre-existing fractures that resulted in the fragmentation of western Gondwana and the opening of Central and South Atlantic Oceans.