TOC and SOM Analyses of Anambra Basin Mamu Shale Outcropped at Okpekpe, South-South Nigeria

Abstract

The Mamu Formation of the Anambra Basin is a significant stratigraphic unit with potential hydrocarbon source rock characteristics. This study evaluates the Total Organic Carbon (TOC) and Soluble Organic Matter (SOM) content of Mamu shale outcrops at Okpekpe, South-South Nigeria, to assess their organic richness and hydrocarbon generation potential. Fourteen shale samples (R1- R14) were analyzed, revealing TOC values ranging from 0.22% to 2.67%, with an average of 1.41%. SOM concentrations varied between 805 ppm and 3,321 ppm, averaging 1,947 ppm. The results indicate that some samples (R5, R8, R11, R13) possess good to excellent TOC values (>2%), suggesting significant hydrocarbon potential. A moderate positive correlation (R² ≈ 0.5) between TOC and SOM implies that organic matter quantity influences hydrocarbon yield. This study contributes to understanding the source rock potential of the Mamu Formation in the Anambra Basin.