Tack, L,  Thomas, M,  Wingate, D,  Liégeois, J.P.,  Fernandez-Alonso, M & Deblond, A. 2001. ‘Early Neoproterozoic magmatism (1000-910 Ma) of the Zadinian and Mayumbian Groups (Bas-Congo): onset of Rodinia rifting at the western edge of the Congo craton’. Precambrian Research 110: 277-306. Amsterdam : Elsevier.  I.F. 3.736.

Article in a scientific Journal / Article in a Journal

Abstract In Central Africa, the West Congo (or West Congolian) belt extends subparallel to the Atlantic coast between 1° and 12° S along the western edge of the Archaean Congo craton. In the last three decades, the role of this belt in the geodynamic modelling of the Pan-African - Brasiliano belts, in particular since Gondwana and Rodinia supercontinent reconstructions, has been the subject of episodic discussion. We present new ion microprobe (SHRIMP) U-Pb zircon ages as well as some geochemical and isotopic analyses for key igneous units within the central part of the West Congo belt. We integrate these data with revised geological information in an updated geological map of the entire belt (1:1,000,000 scale), including a synthetic type cross-section of the belt and an updated lithostratigraphic chart of the "West Congo Supergroup". From oldest to youngest, the latter comprises the Zadinian, Mayumbian and West Congolian "Groups". Emplacement of early Zadinian peralkaline granites (Noqui massif, 999 ± 7 Ma) and rhyolites (Palabala) is accompanied by incipient rifting sedimentation, corresponding to the onset of transtensional rifting along the craton preferentially in a transverse mega-shear setting. Subsequently, the upper Zadinian series correspond to a thick (1600-2400 m) basaltic sequence (Gangila) with typical geochemical characteristics of continental flood basalts (CFB) and Nd = -2.4 ± 1.2. The Gangila basalts, marking major rifting associated to pull-apart, are rapidly followed by the Mayumbian rhyolitic lavas (3000-4000 m thick sequence; 920 ± 8 Ma for the base of the rhyolites and 912 ± 7 Ma for their top). The felsic lavas are intruded by coeval high-level (micro)granites, whose emplacement is dated respectively at 924 ± 25 Ma (Mativa body) and at 917 ± 14 Ma (Bata Kimenga body) in the Lufu massif (Nd of this felsic volcanic-plutonic sequence = -11 ± 2). This huge bimodal magmatism is similar to the Parana and Deccan provinces, sharing similar lithospheric sources. It corresponds to the initial, transtensional rifting stage along the western edge of the Congo craton before Rodinia breakup. No Mesoproterozoic events are recorded in the area: no Zadinian nor Mayumbian "orogeny" nor "aulacogen" (thus, no local segment of the Kibaran belt), no Mesoproterozoic ophiolites nor suture zone...

• IGCP 440; Assembly and Breakup of the Rodinia Supercontinent