Regressive Shoreface Depositional System of the Cretaceous Yolde Formation of the Gongola Sub-Basin Northern Benue trough N. E. Nigeria
B. Shettima *
Department of Geology, University of Maiduguri, Nigeria.
M. Bukar
Department of Geology, University of Maiduguri, Nigeria.
B. Shettima
Department of Geology, University of Maiduguri, Nigeria.
B. Shettima
Department of Geology, University of Maiduguri, Nigeria.
H. I. kamale
Department of Geology, University of Maiduguri, Nigeria.
I. A. Yerima
Department of Geology, University of Maiduguri, Nigeria.
A. O. Umaru
Department of Geology, University of Maiduguri, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The characterization of lithofacies of the Yolde Formation at Briyel town in the Gongola Sub-basin of the Northern Benue Trough indicated coarsening upwards cycles composed transitional succession of six lithofacies that comprises of trough cross-beds, planar cross-beds, massive beds, ripple laminations, parallel laminations and mudstone. This coarsening and thickening upward symmetry is defined by a densely bioturbated mud dominated lower part transitionally grading into heterolithic interval composed thinly bedded sandstone and mudstones both of which developed below fair-weather wave base. This is capped by a succession of moderately bioturbated trough-planar crossbedded sandstone with poly-directional paleocurrent system. These assemblages reflect shoreface deposits and devoid of hummocky cross-stratification therein may account for a moderate wave oceanographic system. Evolution of this setting in the Gongola Sub-basin is indicative of a scenario of a broaden coastline in the coastal palaeogeography of the Yolde Formation typically suppressing due to frictional damping.
Keywords: Shoreface, Yolde formation, depositional system, Gongola Sub-basin.