Zircon dating and mineralogy of the Mokong Pan-African magmatic epidote-bearing granite (North Cameroon)

Zircon dating and mineralogy of the Mokong Pan-African magmatic epidote-bearing granite (North Cameroon)

We present the mineralogy and age of the magmatic epidote-bearing granite composing most of the Mokong pluton, in the Central Africa orogenic belt (North Cameroon). This pluton intrudes Neoproterozoic (~830 to 700 Ma) low- to high-grade schists and gneisses (Poli-Maroua group), and is crosscut or in...

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Bibliographic Details
Published in:International journal of earth sciences : Geologische Rundschau Vol. 105; no. 6; pp. 1811 - 1830
Main Authors: Tchameni, R., Sun, F., Dawaï, D., Danra, G., Tékoum, L., Nomo Negue, E., Vanderhaeghe, O., Nzolang, C., Dagwaï, Nguihdama
Format: Journal Article
Language:English
Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2016
Springer Nature B.V
Subjects:
Crystallization
Earth and Environmental Science
Earth Sciences
Geochemistry
Geology
Geophysics/Geodesy
Granite
Magma
Mineral Resources
Mineralogy
Minerals
Original Paper
Sedimentology
Stone
Structural Geology
Zirconium
Cameroon
Africa
Magmatic epidote-bearing granite
North Cameroon
Central Africa Pan-African orogenic belt
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Summary:We present the mineralogy and age of the magmatic epidote-bearing granite composing most of the Mokong pluton, in the Central Africa orogenic belt (North Cameroon). This pluton intrudes Neoproterozoic (~830 to 700 Ma) low- to high-grade schists and gneisses (Poli-Maroua group), and is crosscut or interleaved with bodies of biotite granite of various sizes. The pluton is weakly deformed in its interior, but solid-state deformation increases toward its margins marked by narrow mylonitic bands trending NNE–SSW. The magmatic epidote granitic rocks are classified as quartz monzodiorite, granodiorite, monzogranite, and syenogranite. They are medium- to coarse-grained and composed of K-feldspar + plagioclase + biotite + amphibole + epidote + magnetite + titanite + zircon + apatite. In these granites, the pistacite component [atomic Fe +3 /(Fe 3+  + Al)] in epidote ranges from 16 to 29 %. High oxygen fugacity (log ƒO 2  − 14 to −11) and the preservation of epidote suggest that the magma was oxidized. Al-in hornblende barometry and hornblende–plagioclase thermometry indicate hornblende crystallization between 0.53 and 0.78 GPa at a temperature ranging from 633 to 779 °C. Zircon saturation thermometry gives temperature estimates ranging from 504 to 916 °C, the latter being obtained on samples containing inherited zircons. U/Pb geochronology by LA-ICP-MS on zircon grains characterized by magmatic zoning yields a concordia age of 668 ± 11 Ma (2 σ ). The Mokong granite is the only known occurrence magmatic epidote in Cameroon, and is an important milestone for the comparison of the Central Africa orogenic belt with the Brasiliano Fold Belt, where such granites are much more abundant.
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ISSN:1437-3254
1437-3262
DOI:10.1007/s00531-015-1276-x