Micropaleontological and sedimentological analyses of carbonates rocks in parts of Sokoto Basin, Nigeria: implications for paleoecological interpretation and exploration efforts

Abstract

This study presents a detailed analysis of the Paleocene and Maastrichtian marine sediments in the Sokoto Basin, Nigeria, using boreholes GSN – BH – 2051 and GSN – BH – 4051, respectively. This study is aimed at integrating sedimentological, micropaleontological and petrographic data in paleoecologic interpretation of depositional environments of the Sokoto Basin. The methods adopted in this research involved the examination of ditch cuttings, carbonate thin sections, and microfossils analyses from the boreholes drilled in Sokoto Basin. The sedimentological data from the borehole showed that the studied stratigraphic unit comprises mainly fine to medium-grained limestone facies, sparitic intraclastic packstone and oolitic-elmicrite wackestone facies. The microfacies obtained from petrography data revealed micro-fossils abundance and diversity associated with the onset of shallow marine transgression which resulted in the deposition of the Dange and Kalambaina Formations, respectively. The assemblages of the larger foraminifera (Opercullnoides bermudezi) and the larger ostracod (Bairdia iIaroensis) in the borehole sections further suggested marginal marine depositional environment for the Kalambaina and Gamba Shale Formations. The paleoecological interpretation suggests varying salinities and dysaerobic conditions during deposition, with implications for understanding basin evolution. The study concludes by highlighting the importance of integrating multiple methods for a detailed understanding of paleoecological and depositional environment of Sokoto sedimentary  basin.