Petrology and CHIME geochronology of Pan-African high K and Sr/Y granitoids in the Nkambe area, Cameroon

Tetsopgang, Samuel; Suzuki, Koji; Njonfang, Emmanuel

doi:10.1016/j.gr.2008.01.012

Cited by 38 publications

(19 citation statements)

References 38 publications

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“…These characteristics are similar to those of the biotite granitoid and two -mica granitoid (K 2 O = 4.4 -6.8 wt% and K 2 O/Na 2 O = 1.0 -2.4: Tetsopgang et al, 2006Tetsopgang et al, , 2008 and suggest that these lithologies belong to the high K calc -alkaline series and/or shoshonitic series (Peccerillo and Taylor, 1976) (Fig. 5h).…”

Section: Whole-rock Chemistrysupporting

confidence: 68%

“…Therefore it appears that the relatively high -pressure and temperature conditions of metamorphism of the host lithologies support the estimated emplacement depth of the biotitehornblende granitoids. These relatively high -pressure conditions took place most likely during the collisional and post -collisional tectonic setting (Tetsopgang et al, 2008) with a probable crust thickening in addition to the vertical uplift that favored the genesis of granitoids in this region.…”

Section: P-t Estimationsmentioning

confidence: 98%

“…The chemical Th -U -total Pb isochron method (CHIME: Suzuki and Adachi, 1991) gave zircon and monazite ages of 569 ± 12 to 558 ± 15 Ma and 533 ± 12 to 524 ± 28 Ma for the foliated and massive biotite granitoids, respectively (Tetsopgang et al, 2008). The ages of the two -mica granite and the magnetite -bearing two -mica granite are 530 Ma ± 9 Ma and 510 ± 25 Ma, respectively (Tetsopgang et al, 1999), and the age of the hornblendebiotite granitoids is estimated to be about 550 Ma (Tetsopgang et al, 2008).…”

Section: Geologic Outlinementioning

confidence: 99%

“…The ages of the two -mica granite and the magnetite -bearing two -mica granite are 530 Ma ± 9 Ma and 510 ± 25 Ma, respectively (Tetsopgang et al, 1999), and the age of the hornblendebiotite granitoids is estimated to be about 550 Ma (Tetsopgang et al, 2008).…”

Section: Geologic Outlinementioning

confidence: 99%

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Emplacement P-T conditions of Pan-African biotite-amphibole granitoids in the Nkambe area, Cameroon

Tetsopgang¹,

Enami²,

Njonfang³

2011

Journal of Mineralogical and Petrological Sciences

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Biotite -and amphibole -bearing monzogranite, quartz monzonite, and tonalite intrude into the biotite granitoids and biotite -hornblende gneisses of the Pan -African belt in the Nkambe area, northwestern Cameroon. The common mineral assemblage in these rocks is amphibole + biotite + plagioclase + K -feldspar + quartz + zircon + apatite; however, their modal composition varies in each rock -type. Most amphibole grains are relatively homogeneous and locally have slightly Al -rich rims. They are mostly ferro -edenite or ferropargasite, and in a tonalite sample, there is magnesiohornblende with less aluminous and more magnesian composition. The amphibole + biotite + plagioclase + K -feldspar + quartz assemblage was affected by several pressure -sensitive and H 2 O -free reactions. The ferro -edenite -and/or ferropargasite -bearing samples show similar pressure -temperature (P -T) ranges of 0.46 -0.50 GPa/655 -690 °C and 0.43 -0.69 GPa/675 -705 °C. In contrast, the magnesiohornblendebearing tonalite records lower temperature conditions of 0.77 GPa/610 °C, which is attributed to subsolidus reequilibration during cooling. The P -T estimates for the biotite -amphibole granitoids in this and previous studies suggest that relatively high -pressure granitoids are widespread in the Nkambe area.

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Section: Whole-rock Chemistrysupporting

confidence: 68%

Section: P-t Estimationsmentioning

confidence: 98%

Section: Geologic Outlinementioning

confidence: 99%

Section: Geologic Outlinementioning

confidence: 99%

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Emplacement P-T conditions of Pan-African biotite-amphibole granitoids in the Nkambe area, Cameroon

Tetsopgang¹,

Enami²,

Njonfang³

2011

Journal of Mineralogical and Petrological Sciences

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“…These include the Paleoproterozoic gneissic basement, Mesoproterozic to Neoproterozoic schists and gneisses of Poli, Yaoundé, and Lom, and Pan African granitoids whose ages range from the early stage of the deformation (orthogneisses) to the late uplift stages of the belts [42]. Examples of geochronological dating of those rocks include 520± 20 Ma for Poli and 498 ± 5 Ma for Lom (Rb-Sr age on whole-rock) [43], 525 Ma for Goutchoumi and 521 ± 19 Ma for Linté (Rb-Sr age on whole rock), 530 ±10 Ma and 510 ± 25 Ma, 569 ± 12 to 558 ± 24 Ma, and 533 ± 12 to 524 ± 28 Ma for Nkambe [44,45], 600 Ma for Ngondo [46], 620 ± 10 Ma for granulite in Yaoundé [47], 2.1 Ga paleoproterozoic for the garnet amphibolites and tonalitic to trondhjemitic gneisses, and 618 Ma magmatic rock of Tonga [48], and 1617 ± 16 Ma (Paleoproterozoic in age) for the metasediments and 600 Ma for the monzodiorite of Bafia Group [49].…”

Section: Geochronology Of the Cameroon Mobile Beltmentioning

confidence: 99%

U-Pb Zircon Age: Preliminary Data Evaluating the Earth History Recorded by Two Basement Rocks (Granitic Pegmatite and Mica-Schist) in Mamfe Basin (Sw Cameroon, Central Africa)

Kanouo¹

2017

J Geol Geophys

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Zircon crystals from two basement rocks (granitic pegmatite and mica-schist) in the Mamfe Basin were studied to provide petrogenetic and geochronologic constraints, therefore were characterized and dated by LA-Q-ICP-MS analytical techniques, after their internal textural features were determined.Zircon crystals with oscillatory zoning from the granitic pegmatite exceed 200 µm are mainly euhedral to prismatic. The U (≤169 ppm), Th (≤240 ppm), and Th/U (0.6-1.7) are within the range of zircon crystallized in crustal magmatic environment. Zircon crystals from the mica-schist are ˂100 to ˃200 µm in size, have magmatic (e.g., euhedral prismatic with oscillatory zone) and metamorphic (e.g., form round soccer ball, sub-hedral with overgrowth) features. The U (23-687 ppm), Th

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The Western Cameroon Highland margin: Is there any geomorphometric evidence of active tectonics?

et al. 2022

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The Western Cameroon Highland margin (WCHM) within the West African margin displays an uneven high relief. Its evolutionary model in vogue suggests the tectonic activity of the Cameroon Volcanic Line (CVL). An evident question in this regard is whether there is any geomorphometric evidence in support of what is this widespread view? We evaluate this question using field controls and geomorphometric indices of active tectonics derived for 13 main river basins with the help of digital elevation model (DEM)‐30 m data. The WCHM is developed on Proterozoic granite‐gneissic basement and the Cretaceous to Recent volcano‐sedimentary cover and was affected by regional active tectonic features. It is marked by transient signs of different landscape evolutionary stages recorded by the relief and drainage network; shown by gradual adjustment of rivers to equilibrium stages; and cautioned by a greatest variation of DEM‐based geomorphic indices. These indices, hypsometric integral (HI = 0.10–0.35), topography relief (TR = 595–2,710), topography dissection (TD = 114–829), valley floor width to valley height ratio (Vf arg = 0.61–14.91), transverse topographic symmetric factor (T‐index = 0.18–0.49), and basin asymmetric factor (AF = 1.08–24.37) highlight elevated and roughness character of that margin, from the Benue Trough and culminating to the CVL. River longitudinal profiles reveal variably and deeply incised WCHM by the drainage network, reinforced by ongoing tectonic activities. Knickpoints (Kps), stream length‐gradient (SL), uplift (U = 1.17–2.0), and a variety of normalized steepness (Ksn = 11.63–635.16) evidence the diversity and preeminent tectonic controls. The above results show that the WCHM is widely considered to be the consequence of the mantle dynamisms and regional tectonics since Proterozoic, the CVL activities, and the erosional processes.

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Petrology and CHIME geochronology of Pan-African high K and Sr/Y granitoids in the Nkambe area, Cameroon

Cited by 38 publications

References 38 publications

Emplacement P-T conditions of Pan-African biotite-amphibole granitoids in the Nkambe area, Cameroon

Emplacement P-T conditions of Pan-African biotite-amphibole granitoids in the Nkambe area, Cameroon

U-Pb Zircon Age: Preliminary Data Evaluating the Earth History Recorded by Two Basement Rocks (Granitic Pegmatite and Mica-Schist) in Mamfe Basin (Sw Cameroon, Central Africa)

The Western Cameroon Highland margin: Is there any geomorphometric evidence of active tectonics?

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