TITLE:
Petrology of the Volcanic Rocks from Bioko Island (“Cameroon Hot Line”)
AUTHORS:
Fadimatou Ngounouno Yamgouot, Bernard Déruelle, Isaac Bertrand Gambie Mbowou, Ismaïla Ngounouno
KEYWORDS:
Petrology, Geochemistry, Lavas, Bioko, Cameroon Hot Line
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.3,
March
25,
2015
ABSTRACT: Bioko island (3008 m
a.s.l.), is composed of the alkaline basaltic lavas (basalts and hawaiites)
with xenoliths. These lavas have a microlitic textureand consisted of euhedral
to subhedral phenocrysts(>1
mm) of olivine (0.83 62-67Ab35-32Or3-1) phenocrysts are present
only in hawaiites. In Harker diagrams, SiO2, Al2O3,
Na2O and K2O contents of the lavas increase and Fe2O3,
MgO and CaO decrease with increasing differentiation from basalts to hawaiites.
The compatible elements Ni, Cr and V decrease strongly in basalts and remain at
low levels in hawaiites. Basaltic lavas from Bioko lavas have low Hf contents
(4.2 - 9.2 ppm) and consequently higher Hf/Zr ratios (50 - 90) than those
(