Géochimie des laves basaltiques récentes des zones Nord et Est de Ngaoundéré (Cameroun, Plateau de l’Adamaoua, Afrique centrale): pétrogenèse et nature de la source

Nkouandou, OF; Ngounouno, Ismaı̈la; Dennielou, Bernard

doi:10.4314/ijbcs.v4i4.63038

Cited by 7 publications

(12 citation statements)

References 39 publications

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“…It overhangs the western Koutine plain in the West, Kontcha basin to the North, Galim and Sambolabo lowlands to the East and South, respectively. The previous K-Ar (Dunlop 1983;Fitton& Dunlop 1985;Fitton 1987) and 40 Ar/ 39 Ar ages (Lee et al, 1994a(Lee et al, , 1994bMarzoli et al 1999), determined on volcanic massifs and lava flows from CVL and AP, do not clearly support a hot-spot origin as the model of Wilson-Morgan (Wilson 1965(Wilson , 1973Morgan 1971Morgan , 1972a. Then, the lack of age progression along the CVL magmatism renders the age determination of each volcano of the line indispensable to modelize the entire CVL.…”

Section: Introductionmentioning

confidence: 88%

New K–AR ages of tchabal mbabo alkaline volcano massif, Cameroon volcanic line and adamawa plateau (central Africa)

Aminatou¹,

Faarouk²,

Temdjim

et al. 2016

IJAG

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Tchabal Mbabo in Central Africa is a voluminous volcano massif composed of alkali lava series. K-Ar geochronology data obtained from three samples of basanite -trachyandesite composition defined at least two volcanic activities. The first at end Eocene (38.22 ± 0.80 Ma) and the second during Oligocene (28.88 ± 0.61 and 28.60 ± 0.60Ma). The distribution of different ages along the Cameroon Volcanic Line is difficult to council with any migration of magmatic activity, as previously suggested. The most realistic scenario for the formation of Cameroon Line is that the ascent of lavas has been favored by the crustal discontinuities inherited from the Pan-African orogeny and reactivated during Mesozoic and Cenozoic. ICP MS and ICP AES analyses show that basanite lavas are the result of 2 % melting of sub-lithospheric mantle source containing garnet and phlogopite phases; the trachyandesites are formed by fractional crystallization of K-feldspar, amphibole, clinopyroxene and Fe-Ti oxides.

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Section: Introductionmentioning

confidence: 88%

New K–AR ages of tchabal mbabo alkaline volcano massif, Cameroon volcanic line and adamawa plateau (central Africa)

Aminatou¹,

Faarouk²,

Temdjim

et al. 2016

IJAG

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“…Kd used for the calculation of distribution coefficients Di used in this model are taken from Blundy and Wood (2003). Data used here integrate the previous (Nkouandou et al, 2018(Nkouandou et al, , 2010 and newly analyses (Table 1).…”

Section: Fractional Crystallization Modelingmentioning

confidence: 99%

“…Numerous compositions of multi-component mantle sources have been proposed for alkaline lava series worldwide (Stracke et al, 2005). Following the models proposed for the genesis of the magma sources of French Polynesia (Clouard et al, 2000) lava series, we propose three compositions of different mantle sources for this model: (1) High µ (HIMU) type mantle source composed of 18% Mid-Ocean Ridge Basalts (MORB) and 81% depleted mantle with the small amount of pelagic sediment (1%) and phlogopite residue in the garnet stability field, (2) depleted mantle in the spinel stability field and (3) depleted mantle in the garnet stability field (Nkouandou, 2006 for more details). The different mineralogical mantle modes used in the model are from Johnson et al (1990).…”

Section: Partial Melting Rate Determinationmentioning

confidence: 99%

“…Fractional Crystallization modeling with major elements distribution by massbalance crystal fractionation has been attempted by Nkouandou et al (2008) and Nkouandou et al (2010) by using the compositions of the mineral phases present as phenocrysts in the lavas. This model is reexamined in this work where calculated chemical compositions of lavas and proportions of removed mineral phases during differentiation of the magmas were determined using mass-balance computation minimizing the sum of squares of residuals.…”

Section: Fractional Crystallization Modelingmentioning

confidence: 99%

“…Despite the present southwards slope of the plateau, most of the lavas flowed radially around the centers. Previous studies on the Miocene volcanic of Ngaoundéré area (Nkouandou et al, 2008(Nkouandou et al, , 2010Fagny et al, 2012;Mbowou et al, 2013) have constrained the main petrogenesis processes at the origin of Adamawa plateau volcanism. This work presents the petrogenetic models of Miocene volcanism from the North and East of Ngaoundéré, using the unpublished supplement data of basaltic and newly analysed phonolitic and trachytic rocks.…”

Section: Introductionmentioning

confidence: 99%

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Petrogenesis modeling of the alkaline volcanism of Ngaoundéré (Adamawa plateau, Cameroon, Central Africa)

Nkouandou¹,

Mefire²,

Dennielou³

2017

Int. J. Bio. Chem. Sci

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ACKNOWLEDGMENTS Warm thank to 'Agence Universitaire de la Francophonie (AUF)' through 'Projet de soutien aux équipes de recherche n° 51110SU201' for supplement analyses. ABSTRACTNew insights on geochemistry of the alkaline volcanism of Ngaoundéré in Adamawa plateau enable the petrogenesis modelling of Ngaoundéré Miocene lava series. Mass-balance crystal fractionation, closed-system Assimilation, Fractional Crystallization (AFC) and partial melting rate modeling attempted for Ngaoundéré volcanism are re-examined. Inductively Couple Plasma-Mass Spectrometry (ICP-MS) and Inductively Couple Plasma Atomic Emission Spectroscopy (ICP-AES) analyses show that lavas are microlitic porphyritic textures. Decrease of major element (MgO, Fe 2 O 3 , TiO 2 , CaO) with increasing SiO 2 contents results from fractionation of olivine, clinopyroxene and Fe-Ti-oxides in the parental basaltic magma. Similarly, for felsic magma, decrease in Al 2 O 3 , Na 2 O and K 2 O contents depends upon feldspar fractionation and decrease in P 2 O 5 from apatite fractionation, thus underline a typical feature of alkaline basaltic lavas of Ngaoundéré volcanism. The results evidence the differentiation by fractional crystallization process. Parental magmas of Ngaoundéré volcanism have undergone a low partial melting rate (2 to 3 %) of the heterogeneous mantle source.

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Wehrlite xenoliths and petrogenetic implications, Hosséré Do Guessa volcano, Adamawa plateau, Cameroon

et al. 2022

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Peridotite xenoliths of wehrlite composition, scarcely known in Adamawa plateau, Cameroon, were sampled by Mio-Pliocene basanites from Hosséré Do Guessa volcano. Their origins are discussed and elucidated trough petrography and mineral chemistry. Studied wehrlites exhibit poikilitic or protogranular textures and are composed of four main mantle phases (high Mg-olivine, augite, enstatite and Al-spinel). Petrographic and microprobe (Camebax SX100) chemical data (Fo90.8-91.4 olivine, Wo39.4-42.0 augite, En90.5-91.1 enstatite and Al-spinel) suggest a mantle origin for the Hosséré Do Guessa wehrlites. Hence, these rocks could not be considered cumulate. They have been equilibrated between 1,140 and 1,220°C, at pressures of 1.5–2.0 GPa, at 50–66 km deep, below the crust-mantle boundary. Wehrlites might result in reactions with carbonate/carbonatite melt, accompanying CO2 degassing and metasomatism by fluid phases. They suffered transpressional tectonics, during movement at Tertiary times of Pan-African strike-slip-faults, after solid-state tectonic relaxation.

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Géochimie des laves basaltiques récentes des zones Nord et Est de Ngaoundéré (Cameroun, Plateau de l’Adamaoua, Afrique centrale): pétrogenèse et nature de la source

Cited by 7 publications

References 39 publications

New K–AR ages of tchabal mbabo alkaline volcano massif, Cameroon volcanic line and adamawa plateau (central Africa)

New K–AR ages of tchabal mbabo alkaline volcano massif, Cameroon volcanic line and adamawa plateau (central Africa)

Petrogenesis modeling of the alkaline volcanism of Ngaoundéré (Adamawa plateau, Cameroon, Central Africa)

Wehrlite xenoliths and petrogenetic implications, Hosséré Do Guessa volcano, Adamawa plateau, Cameroon

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