Foraminifera and Sequence Stratigraphy Study of the Early Maastrichtian to Paleocene Sediments of Kalambaina Formation, Sokoto Basin, Borth western Nigeria

Abstract

Fieldwork was conducted at the Kalambaina Limestone Quarry in Wammako, Sokoto State, to collect samples for a detailed foraminiferal study. The aim was to determine the relative age, paleo-environment of deposition, and the impact of sea level changes on the sediments. A total of eleven samples were collected and analyzed using methods including disaggregation, digestion, washing, and microscopic examination. The results revealed a stratigraphic interval rich in benthic foraminifera, both calcareous and agglutinated, but devoid of planktonic forms. Specifically, the recovered calcareous benthic foraminifera included Rosalina koeneni (12.5% relative abundance), Pararotalia tuberculifera (8.7%), Gavelinella lellingensis (6.3%), Pararotalia perclara (5.2%), Elphidiella africana (4.9%), and Planulina nacatochensis (7.8%). The agglutinated forms identified were Haplophragmoides hausa (9.1%), Trochamina wickedeni (7.4%), Haplophragmoides sp. (6.6%), Miliammina telemaquensis (5.5%), and Haplophragmoides talokaensis (4.2%). Associated fossils included moderate quantities of ostracods and a few echinoderm spines. The foraminiferal assemblage aligns with previous studies that date the sediments from Maastrichtian (Upper Cretaceous) to Paleocene. The paleo-environment ranged from a hypersaline epeiric sea to a lagoonal deposit, suggesting significant sea level fluctuations. This study reaffirms the Maastrichtian to Paleocene age of the Kalambaina Formation, contradicting earlier Paleocene-only attributions and challenging the validity of the "Sokoto Group" nomenclature.