FIELD GEOLOGIAL AND GEOCHEMICAL ASPECTS OF MARBLE OCCURENCES IN OSOSO, SOUTHWESTERN NIGERIA

Abstract

Previous geological investigations in Ososo did not combine subsurface and outcrop data to determine 
lithostratigraphic relationship, and did not ascertain potential uses of marble bodies in the area. Yet, these are part of 
the considerations in assessing the economic value of marble deposits. For that reason, this study integrated outcrop 
and core data to establish the spatial distribution and relationship of the rock types in the area. It also aimed to 
classify the marble bodies and evaluate their potential uses from X-Ray fluorescence and X-Ray diffraction data. In 
upward younging order, the rocks found are granite-gneiss and gneiss, calc-silicate gneiss, whitish and gray marble, 
garnet-biotite-muscovite schist, quartzite, intrusive granite and gabbro. Folds, pinch and swell structures, and 
boudinages deform leucosomes within the granite-gneiss. They indicate a change from compressional regime to 
extensional regime. They also indicate more than one deformational phase. In the whitish marble, CaO ranges from 
50.79 to 52.13 wt %, and MgO ranges from 0.01 to 0.25 wt %. They are high purity calcitic marble, and are useful 
in manufacturing sugar. The gray marble contains 20.10 wt % CaO and 40.75 wt % MgO. They are pure dolomite, 
and useful as suitable flux material in steel plants.