Sub-continental lithospheric mantle structure beneath the Adamawa plateau inferred from the petrology of ultramafic xenoliths from Ngaoundéré (Adamawa plateau, Cameroon, Central Africa)

Nkouandou, Oumarou Faarouk; Bardintzeff, Jacques-Marie; Fagny, Aminatou M.

doi:10.1016/j.jafrearsci.2015.07.004

Cited by 14 publications

(1 citation statement)

References 72 publications

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“…For example, Burke [] suggests the CVL should be restricted to younger (i.e., ≤30 Ma) volcanic edifices from Mount Oku to Pagalú whereas others suggest the CVL continues along a NE trend to the Kapsiki Plateau and possibly Lake Chad [ Moreau et al ., ; Déruelle et al ., ; Ngounouno et al ., ; Yokoyama et al ., ; Mbowou et al ., ; Njome and de Wit , ]. Furthermore the source or sources of the CVL is debated as the rocks show evidence of sublithospheric (e.g., mantle‐plume) and lithospheric mantle components [ Halliday et al ., ; Lee et al ., ; Ballentine et al ., ; Marzoli et al ., ; Aka et al ., ; Rankenburg et al ., ; Yokoyama et al ., ; Njome and de Wit , ; Asaah et al ., ; Nkouandou et al ., ]. Although many studies favor a mantle‐plume model for the CVL [cf.…”

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confidence: 99%

Late Cretaceous intraplate silicic volcanic rocks from the Lake Chad region: An extension of the Cameroon volcanic line?

Shellnutt

Lee

Torng³

et al. 2016

Geochem Geophys Geosyst

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Silicic volcanic rocks at Hadjer el Khamis, near Lake Chad, are considered to be an extension of the Cameroon volcanic line (CVL) but their petrogenetic association is uncertain. The silicic rocks are divided into peraluminous and peralkaline groups with both rock types chemically similar to within‐plate granitoids. In situ U/Pb zircon dating yielded a mean 206Pb/238U age of 74.4 ± 1.3 Ma indicating the magmas erupted ∼10 million years before the next oldest CVL rocks (i.e., ∼66 Ma). The Sr isotopes (i.e., ISr = 0.7021–0.7037) show a relatively wide range but the Nd isotopes (i.e., 143Nd/144Ndi = 0.51268–0.51271) are uniform and indicate that the rocks were derived from a moderately depleted mantle source. Thermodynamic modeling shows that the silicic rocks likely formed by fractional crystallization of a mafic parental magma but that the peraluminous rocks were affected by low temperature alteration processes. The silicic rocks are more isotopically similar to Late Cretaceous basalts identified within the Late Cretaceous basins (i.e., 143Nd/144Ndi = 0.51245–0.51285) of Chad than the uncontaminated CVL rocks (i.e., 143Nd/144Ndi = 0.51270–0.51300). The age and isotopic compositions suggest the silicic volcanic rocks of the Lake Chad region are related to Late Cretaceous extensional volcanism in the Termit basin. It is unlikely that the silicic volcanic rocks are petrogenetically related to the CVL but it is possible that magmatism was structurally controlled by suture zones that formed during the opening of the Central Atlantic Ocean and/or the Pan‐African Orogeny.

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