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Tchabal Gangdaba massif in the Cameroon Volcanic Line: a bimodal association |
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| Authors: | Zénon Itiga Jacques-Marie Bardintzeff Pierre Wotchoko Pierre Wandji Hervé Bellon |
| Institution: | 1. Institute for Geological and Mining Research (IRGM), Branch of Volcanologic and Geophysics Research (ARGV), P.O. Box 4110, Yaoundé, Cameroon 2. IUFM, Univ Cergy-Pontoise, 95000, Cergy-Pontoise, France 3. Univ Paris-Sud, Laboratoire de Pétrographie-Volcanologie and équipe Planétologie, UMR IDES 8148, Bat. 504, 91405, Orsay, France 4. CNRS, Orsay, 91405, Orsay, France 5. école Normale Supérieure, Laboratoire de Géologie, Univ Bamenda, B.P. 39, Bamenda, Cameroon 6. école Normale Supérieure, Laboratoire de Géologie, Univ Yaoundé I, B.P. 47, Yaoundé, Cameroon 7. CNRS UMR 6538 Domaines océaniques, UBO-IUEM, Université européenne de Bretagne, 6 av. Le Gorgeu, CS 93837, 29238, Brest Cédex 3, France |
| Abstract: | Tchabal Gangdaba (TG) volcanic massif, which is a part of the continental sector of the Cameroon Volcanic Line (CVL), is dated between 34.4 and 25.1 Ma. It displays mafic lavas (picrobasalt and basanite, 41–43 wt % SiO2) and felsic lavas (rhyolite, 68–73 wt % SiO2). The lack of intermediate rocks evidences a pronounced Daly gap between 43 and 68 wt % SiO2, which corresponds to an important time span of 3.4 Ma. It is interpreted as due to extensive fractional crystallization under peculiar thermodynamical conditions. Felsic lavas yield strong negative anomalies in Ba, Sr and Eu (0.1?206Pb/204Pb?207Pb/204Pb?208Pb/204Pb? |
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