Savanna Journal of Basic and Applied Sciences 2(1):53-60
Paleoenvironmental Interpretation of Cenomanian-Coniacian Succession Within Yolo Town, Part of the Gongola Sub-Basin, Northeastern Nigeria
Grema H.M., Abdulkarim M., Ibrahim H.A
ABSTRACT
Field mapping, granulometric and micropaleontological analyses were employed to examine the lithostratigraphy and re-construct
the palaeo-depositional environments of the Cretaceous Pindiga and Yolde Formations within the Gongola sub-basin of the
Northern Benue Trough. The Yolde Formation is characterized by fine-grained, tabular and cross stratified sandstones intercalated
with silty-mudstone; with disharmonic, non-cylindrical folds which are consistent with soft sediment deformation that may be
result of hydroplastic slumping of unlithified sandstone beds in energized depositional environment. Grain size analyses indicate a
fluvial depositional environment with proximal sediment source. The Pindiga Formation is made up of mainly shales and
fossiliferous limestone. Foraminiferal assemblages from the Pindiga Formation are mainly of agglutinated benthic taxa dominated
by Haplophragmoides and Ammobaculites, which indicate brackish water, marsh to lagoon environment. However, their diversity
as well as abundance is low compared to the Ostracods, of which Ovocytheridea symmetrica with smooth shells and lack of
ornamentation suggest shallow marine depositional environment. The presence of both hypersaline (Cytherella sp.) and hyposaline
(Brachycythere ekpo) species in the study area also indicate a brackish water depositional environment.
