Comparison between the stratigraphy of the eastern and western parts of the Gongola sub-basin, Northern Benue Trough, Nigeria: The role of tectonics and the Neogene Biu basalt emplacement on the resultant topography of the eastern part of the Gongola sub-

Abstract

Detailed field mapping exercise was carried out as well as system logging of the various
outcropping lithostratigraphic units in the eastern part of the Gongola sub-basin east of
Gongola River of the northern Benue Trough with the aim of establishing any similarity
or otherwise with the western part of the sub-basin west of Gongola River. The study
reveals that the pre-Aptian to Coniancian lithostratigraphy succession of both areas of the
sub-basins are somewhat similar and comprises the following units; the Bima group (lower,
middle, and upper Bima formations) followed by the Yolde formation, the Kanawa forma-
tion. The mid-Turonian sandy equivalents are directly above the Kanawa formation and are
represented by the Deba-Fulani Member restricted to the southern part of the Gongola
sub-basin, the Dumbulwa Member restricted to the northern part of the sub-basin and the
Gulani formation confined to the eastern part of the sub-basin. The mid-Santonian tectonic
event affected the pre-Santonian succession resulting in the folding, faulting, and uplifting
of the various lithostratigraphic units. This subsequently led to the formation of synclines
and anticlines. The pre-Santonian Fika shale presumed to have been directly above the
Gulani formation is rarely observed in the eastern Gongola sub-basin compared to the
western sub-basin where it is found in several places. This suggests that the denudational
activities spanning from Santonian to Paleocene in the eastern Gongola sub-basin were
severe before the emplacement of the Neogene Biu basalt that slowed down the activities.
The Campanian–Maastrichtian and the Paleocene successions are restricted to the west-
ern Gongola sub-basin