Cretaceous Patti Shales of southern Mid-Niger Basin as an insight to provenance, paleoenvironment, and paleoclimate: a comprehensive study

Abstract

This study focuses on the geochemical, mineralogical, and palynological analyses of Cretaceous Shales of the Patti Formation within the Ahoko section of the southern Mid-Niger Basin, Nigeria. The aim of this research is to understand the provenance, paleoenvironment, and paleoclimate of the Mid-Niger Basin, Nigeria. The samples were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and palynomorph analysis techniques. The results of the geochemical study (XRF) showed that the sediments were mature and recycled because of the high quantities of S_iO₂ (28.759% - 62.107%), Fe₂O₃ (3.493% - 46.079%), Al₂O₃ (9.832% - 24.422%), and K₂O (1.378% - 2.449%), respectively. The results of a mineralogical investigation showed that garnet, muscovite, orthoclase, illite, and osumilite were the least common minerals, with quartz being the most common mineral (33% - 51%) and followed by kaolinite (28% - 47%). Based on geochemical data, the provenance indicates that the sediments originated from felsic igneous provenance. Palynomorph revealed diverse assemblages of terrestrial paleoenvironments from the Campanian to Paleocene ages, including open forest vegetation. Cingulatisporites ornatus, Monocolpites sp., Longapertites sp., Cyathidites minor, Foveotriletes margaritae, Distaverrusporites simplex, Psilatricolporites crassus, Echitriporites trianguliformis, Rugulatisporites caperatus, Verrutricolporites irregularis, Diatom frustules, Tubistephanocolpites cylindricus, Laevigatosporites sp., Monoporites annulatus, Inaperturopollenites sp., and Tricolporopollenites sp. are among the palynomorphs identified in the samples. Additionally, arid to semi-arid climatic conditions at the source area are indicated by the S_iO₂/(Al₂O₃ + K₂O + Na2O) ratios, which have an impact on sediment maturity. The integration of the lithological, geochemical and palynological data has provided insight into the provenance, depositional setting, and paleoclimate of the Cretaceous Patti Shale in the southern Mid-Niger Basin.