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Journal of Geosciences and Geomatics. 2017, 5(1), 1-11
DOI: 10.12691/JGG-5-1-1
Original Research

Petrogenesis of Lava from Wainama West, Mount Oku (CVL): Source Characterization and Magma Evolution

Wotchoko Pierre1, , Nkouathio David Guimollaire2, Kouankap Nono Gus Djibril1, Chenyi Marie-Louise Vohnyui1, 2, Guedjeo Christian Suh1, 2, Bulam Annyta Tangie1, Tchokona Seuwui dieudonne3 and Seplong Yannick1, 3

1Department of Geology, Higher Teacher Training College, University of Bamenda, Bambili, Bamenda, Cameroon

2Department of Earth Sciences, Faculty of Sciences, University of Dschang, Dschang, Cameroon

3Department of Earth Sciences, Faculty of Sciences, University of Yaoundé 1, Yaoundé, Cameroon

Pub. Date: January 05, 2017
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Wotchoko Pierre, Nkouathio David Guimollaire, Kouankap Nono Gus Djibril, Chenyi Marie-Louise Vohnyui, Guedjeo Christian Suh, Bulam Annyta Tangie, Tchokona Seuwui dieudonne and Seplong Yannick. Petrogenesis of Lava from Wainama West, Mount Oku (CVL): Source Characterization and Magma Evolution. Journal of Geosciences and Geomatics. 2017; 5(1):1-11. doi: 10.12691/JGG-5-1-1

Abstract

The Wainama West area belongs to the Cameroon volcanic Line (CVL). Three petrographic types of lavas are identified: basanites, trachytes and rhyolites. Basanites with porphyritic texture are made up of minerals: plagioclase, clinopyroxene, olivine phenocrysts and opaque minerals within a groundmass; trachytes with microlitic-porphyritic texture are composed of phenocrysts of sanidine, hornblende, plagioclases, pyroxene and opaque minerals enclosed in a fine groundmass showing a preferred orientation. Rhyolite shows a microlitic-porphyritic texture made up of quartz, sanidine and opaque minerals in the groundmass. According to their geochemical behaviour, major elements show an enrichment in SiO2 (42.7–70.7 wt.%), Al2O3 (13.7–16.6 wt.%), Na2O (2.3–6.3 wt.%), K2O (1.3–4.9 wt.%) and an impoverishment in MgO (8.3–0.02 wt.%) and CaO (10.0–0.5 wt.%) from basanite to rhyolite. Some binary diagrams indicate a good correlation with some minor elements (Cr, Ba, Zr, Sr, Rb, and Nb) against SiO2. REE patterns of the rocks are characterized by a negative anomaly in Eu (0.3Eu/Eu*0.4) in basanite and weak negative anomaly in Eu (0.1Eu/Eu*0.2) from trachytes to rhyolites, with parallel profiles. The Wainama West lavas are found to have originated from a single primary melt similar to that of OIB and the continental basalt but with slightly higher Nb/Ta content. From the Dy/Yb vs La/Yb diagrams, the major processes resulting to the generation of this primary melt is the partial melting of garnet peridotite, of the high degree (11-12%). The Wainama West alkali lavas were formed in intraplate setting of continental part of the CVL.

Keywords

Wainama West, petrography, geochemistry, partial melting, garnet peridotite

Copyright

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