Primary and Post Depositional Structures of Cretaceous Succession Around Bambam and Its Environs Part of Yola Sub –Basin, Nothern Benue Trough

Abstract

Studies of sedimentary structures of the area around Bambam Town part of Yola
Sub-basin of the Northern Benue Trough northeastern Nigeria have been carried
out. The structures include both primary and post depositional/tectonic structures,
the primary structures are; Tabular cross bedding, Trough cross bedding, Tabular
oblique cross bedding, Convolute cross bedding Ripple marks, Mud cracks. While
the post depositional / tectonic structures include Fold (Anticline), and Recumbent
fold. The structures in most outcrops are sandwiched between strata that have no
major textural differences with the sediments hosting them. The primary structures
include ripple mark, Tabular cross bedding convolute bedding, these occur at the
Upper Bima Formation while Trough and Hummocky cross stratification occur in
Midddle Bima while Pebbles Imbrication occurred at Lower Bima Formation. Post
depositional/tectonic structures are features that developed after deposition of the
sediment, these include Fold (Anticline), Recumbent Fold and they occurred in Upper
Bima Formation. Some of these primary structures of these rocks provide
information about the past environment in which the sediment was deposited.
While the post depositional structures help provide insight about tectonic history
and basin evolution.