Donnees nouvelles sur les laves felsiques de ngaoundere (Adamaoua, ligne du Cameroun): chronologie K-Ar et petrologie

Temdjim, Robert; Njilah, I Konfor; Kamgang, Pierre; Nkoumbou, Charles

doi:10.4314/ajst.v5i2.15338

Cited by 11 publications

(17 citation statements)

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“…One basalt of ankaramitic composition and two trachytic lavas have also been dated as 7.2, 7.8 and 9.8 Ma at Tchabal Nganha volcano massif, by Gouhier et al (1974). Moreover, Temdjim et al (2004) determine the ages of some lavas from the Ngaoundéré area, as follows: 6.2±0.2 Ma for one hawaiite sample, 6.5 -6.8 ± 0.1 Ma for two phonolites and 0.91±0.06 Ma for a mugearite.…”

Section: Discussionmentioning

confidence: 99%

“…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. Moreover, the AP geochronology (Gouhier et al 1974;Temdjim et al 2004; Nkouandou et al 2008 ;Fagny et al 2012) evidenced that these volcanoes are relatively more recent (11 Ma to recent) than those of the CVL (up to 70 Ma to recent, Mbowou et al 2012). Thus, whether the AP magmatism belongs to CVL, as proposed in the Y-shaped model for the whole CVL (Fitton, 1980(Fitton, , 1983, though largely debated (Gouhier et al 1974; Aka et al 2004Aka et al , 2009Nkouandou et al 2010), remains questionable and requires many more age determinations.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…It is delineated at its western and northern parts by many mountains namely Tchabal Nganha (1923 m with an average altitude of 1100 m), Tchabal Ngaoundaba (1960 metres), Tchabal Mbabo (2450 metres) and Mount Mambila (2428 metres). Several petrographic, geochemi-cal [1,2] , geochronological [3] , geophysical [4] and structural [5] studies have been done for the characterization of the Adamaoua plateau. In the structural aspect, the Adamaoua Plateau is made up of a Pan-African metamorphic and plutonic basement bounded to the north by the Adamawa fault and to the south by the << Djérèm and Mbéré >> faults [6] .…”

Section: Introduction and Geological Settingmentioning

confidence: 99%

“…The Neoproterozoic ages are either those of the recrystallized domains, or those of the deposition of sediments, or are characteristic of the metamorphism of the Tcholliré region [28] . Available volcano dating assigns ages Distributed under creative commons license 4.0 of 7-11 Ma (K/Ar method) for the Adamawa lavas [2,25,26,29] , and gave probable Mio-Pliocene ages for the Adamawa volcanism.…”

Section: Introduction and Geological Settingmentioning

confidence: 99%

Geochemistry of Volcanic Rocks of Beka, North East of Ngaoundéré (Adamawa Plateau, Cameroon): Petrogenesis and Geodynamic Context

et al. 2021

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Beka area is situated in the Adamaoua Plateau of Cameroon in central Arica. Lavas in this area has not been studied before the present work.The volcanism of Beka is characterized by basalt, trachyte and phonolite domes and flows. The petrographic study shows that basaltic lavas have porphyritic microlitic textures. The felsic lavas indicate trachytic textures.The rocks are composed of olivine, clinopyroxene, plagioclase and irontitanium oxide minerals for the basalts; clinopyroxene, alkali feldspar (including foids), sphene and titanomagnetite for the felsic lavas. Chemical analyses show that basaltic lavas are basanites. Felsic lavas contain modal feldspathoid (nepheline in phonolites). All these lavas belong to the same series, because the felsic lavas are derived from the differentiation of basaltic lavas by fractional crystallization. They show an alkaline nature according to their geochemistry. Trace elements including Rare Earth Elements characteristics show that rocks emplaced in the Winthin Plate volcanic zone. They derived from an evolved parent magma showing a low degree of partial melting and characteristics closer to a modified and evolved primitive spinel lherzolite.

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“…There is no evidence for volcanic activity between 7 and 1 Ma (Nkouandou et al, 2008;Temdjim et al, 2004). Basaltic lava flows, scoria cones and trachy-phonolitic plugs have been mapped (Temdjim et al, 2003) and some bearing ultramafic xenoliths from the mantle (Temdjim et al, 2010;Nkouandou & Temdjim, 2011).…”

Section: Geological Settingmentioning

confidence: 99%

Polymagmatic processes at monogenetic volcanoes: insights from Baossi monogenetic lava flows, Adamawa Plateau, Cameroon Volcanic Line

Tiabou¹,

Temdjim²,

Ngwa³

et al. 2015

JGG

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This paper presents principally the textural and geothermometric evidence of polymagmatic activity at a monogenetic volcano along the Cameroon Volcanic Line (CVL) in a bid to contribute to the global understanding of how such volume-limited basaltic magmatic systems operate. Preliminary geochemical data presented show that the lavas are alkali basalt and basanite (SiO 2 : 40.42 -47.59 wt%, MgO: 7.61 -9.13 wt%) and are petrographically indistinguishable. They outcrop as low mounds of columnar basalts associated with sparse pyroclastic materials. The lavas are fine, porphyritic with phenocrysts of olivine and clinopyroxene set in a plagioclase microlite-dominated hypocrystalline groundmass. Olivine has two distinct populations: grains that are anhedral to glomerocrystic with spinel and plagioclase inclusions and usually have resorbed margins (olivine 1); and grains that are euhedral, sometimes skeletal, with a thin and well preserved rim (olivine 2). Similarly two clinopyroxene crystal populations are recognizable: clinopyroxene grains that are resorbed, dismembered, with sieve-textured cores and irregular core-rim margins (clinopyroxene 1); and euhedral clinopyroxene grains partially enclosing olivine phenocrysts with sector and hour glass shape zoning (clinopyroxene 2). These textural features suggest that the eruption was caused by an influx of a fresh batch of magma (that crystallized olivine 2 and clinopyroxene 2) into a fractionated crystal mush (olivine 1 and clinopyroxene 1) in the chamber. The crystal mush was re-heated by the intruding basaltic magma resulting in a broad pre-eruption liquidus temperature of 1040 -1156 o C calculated using mineral chemistry of equilibrium olivine-clinopyroxene pairs.

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Donnees nouvelles sur les laves felsiques de ngaoundere (Adamaoua, ligne du Cameroun): chronologie K-Ar et petrologie

Cited by 11 publications

References 0 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)

Geochemistry of Volcanic Rocks of Beka, North East of Ngaoundéré (Adamawa Plateau, Cameroon): Petrogenesis and Geodynamic Context

Polymagmatic processes at monogenetic volcanoes: insights from Baossi monogenetic lava flows, Adamawa Plateau, Cameroon Volcanic Line

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