Petrogenetic Characterization of Talcose Rocks of Ibogunde, Southwestern Nigeria, West Africa

Abstract

Geological mapping on a scale of 1:12,500, mineralogical and geochemical studies of talcose rocks in Ibogunde, Southwestern Nigeria were carried out in order to account for these industrial minerals and to decipher the petrogenesis. Whole-rock major element compositions of eleven (11) talcose and five (5) quartzite rock samples were determined using a PANalytical Axios Wavelength Dispersive spectrometer while the trace and rare earth elements were analysed by LA-ICP-MS (Laser Ablazer Inductively Coupled Mass Spectrometer) at the Central Analytical Facilities, Stellenbosch University, South Africa. Powders of representative talcose rocks were examined for routine qualitative mineral identification using D8-Advance Brunker X-Ray diffractometer at iThemba Lab, Capetown, South Africa. The talcose rocks occurred as small bodies within quartzite in the study area. Under the microscope, it consists of minerals that are bent which are indicative of deformation. Some grains showed radiating textures while others showed parallel alignment of longer axes in preferred orientation. The geochemical result showed higher mean compositions of SiO₂ as 60.12 wt. %; moderate Al₂O₃ (1.19 wt. %); Fe₂O₃ (4.83 wt. %). MgO has generally high value between 25.31 and 29.13 wt. % with an average of 27.59 wt. %. The ratios for La_n/Yb_n, La_n/Sm_n and Ce_n/Yb_n ranged from 2.5 to 22.77, 2.53 to 5.94 and 1 to 23.33, respectively indicated fractionation of the source magma (komatiite). Ni and Cr have high mean concentrations of 1880.45 ppm and 3236 ppm, respectively; which were deduced to be as a result of immobility of these trace elements even under hydrothermal alteration. The results of the X-ray diffraction analysis of the samples showed peaks for talc, chlorite and tremolite. Ternary discrimination plots indicate that the talcose rocks were products of metamorphism of komatiite.

Keyword: Petrogenesis, Talcose rocks, Komatiite, Geochemical.

DOI: 10.7176/JEES/16-1-05

Publication date: March 28^th 2026