Parasequence set analysis of the Maastrichtian to Paleocene stratigraphic succession in the Sokoto sector of Iullemmeden basin, Northwestern Nigeria

Abstract

Detailed geological field mapping of Maastrichtian - Paleocene sedimentary deposits exposed at the Sokoto sector of Iullemmeden Basin  was carried out in this study. The principle of sequence stratigraphy was applied on the exposed outcrops for a better understanding of  their depositional history. Results of the sequence stratigraphic analyses reveal three (3) parasequence types, Two (2) system tracts and  one (1) condensed section. The parasequence of the lower and upper portion of Taloka and Wurno formations are made up of  aggradational and progradational stacking patterns – which all belong to the Lowstand system tracts. Retrogradational stacking pattern  was observed within the Dukamaje, Dange and Kalambaina formations which consist of fossiliferous limestone and shales. The  retrogradational stacking pattern belongs to the Transgressive system tracts. The condensed section which was observed at the  transitional boundary between Wurno and Dange formations near Gada village is represented by a 7 cm thick phosphate bed fused with  glauconite and fossil bones. This indicate a strata associated with the maximum flooding surfaces, represented by sedimentary intervals    deposited during the maximum marine transgression.