Geochemical heterogeneity of Campano- Maastrichtian outcrop sections at Bawa hills, Lokoja/ Basange formation, Anambra basin, mid – western Nigeria.

Abstract

The geochemical heterogeneity of outcrop samples of different sections of bawa hills (Lokoja – basange formation) of the Anambra basin was investigated.Classical methods were employed to determine the percent total organic carbon (TOC) and the soluble organic matter (SOM) while instrumental method was employed to determine the percent nitrogen using the CarloErbaLeco NA-1500. The range of percent %TOC and SOM values obtained were (0.07-3.20) and (100-2,200ppm) respectively. The values of the %TOC and SOM for some of the units were above the 0.5% and 500ppm preliminary threshold values for petroleum generation. The Corg/N ratios range from 0.11 to 105 depicting the organic matter as a mixture of marine and terrestrial source input with a predominance of marine input , and indications of primary product alteration and selective degradation of the organic matter during diagenesis. None of the parameters showed any systematic variation but the %TOC and the SOM exhibited an irregular inverse variation. The entire sample suite exhibited heterogenous geochemical pattern.