STRATIGRAPHY AND S E D I M E N T O L O G Y OF THE AREA AROUND BIDA, NIGER STATE
STRATIGRAPHY AND S E D I M E N T O L O G Y OF THE AREA AROUND BIDA, NIGER STATE
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Date
1989-01
Authors
OLUFEMI, ROBINSON OLUGBEMIRO
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Abstract
The Bida Basin in the Middle Niger is a shallow trough
filled with Campanian — Maastrichi an marine to fluviatile
sediments. Four 1ithostratigraphic units which belong to the
Nupe Group have been identifed in the area o-f study:
Aranaceous, Argillaceous Ironstones and Laterits. These
have been grouped under the Bida Formation, Sakpe Ironstone
Formation, Enagi Formation and Batati Ironstone Formation.
The laterite unit which is Quartenary to Recent in age, is
derived from the Ironstone facies.
The Ironstone Formations are oolitic and pisolitic and
occur at summits of stratigraphic sections while the laterite
unit is a product of the ironstone Formation. By field
observations a cyclic fining upward and local coarsening
upward mode of lithologic succession are deduced for the
Argillaceous and Arenaceous unit (Bida Formation and Enagi
Formation)-
Investigations of the textural properties of sediments
in the area of study show that sandstones in the Bida Basin
a r e poorly sorted, positively skewed and leptokurtic. The
use of bivariate plots for environmental discrimination
indicates an environment of deposition that range from
fluvial to transitional for pebbles, while for sandstones a
more distinct fluvial environment is discernible in the a r e a.
Analysis of assemblages of heavy mineral indicates an
Igneous-Metamorphic provenance for sands within the studied
a r e a , in addition to classification of sandstones, by
framework, matrix and cement composition which indicate a
m o d e r a t e d e g r e e of maturity.
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Sedimentary structures display characteristic bias
towards a relatively shallow regime of deposition.
Assemblages of sedimentary trace fossil range between
Thaiassinoides, Ophiomorpha, Giossifungites, Cruziana to
Zoophycas indicating a rather shallow environment of
deposition, while types and occurrence of sedimentary
structures suggests a fluvial environments f o r the nonironstone
facies units. The ironstone units a r e distinctive
with typical trough cross-bedding, broken shells, and
oolitic—pisolitic texture supporting a high energy possibly
tidal environment o-f deposition. Paleocurrent analysis
indicates a northerly direction of paleoflow with a mean
azimuth value of 359. from cross bedding azimuth measurement. Finally, a general inference can be drawn for a subsidence origin f o r the Bida Basin, based on sediment composition, nan—occurrence of rift or volcanic related
features within the basin and similarity of sediments with that of the Iullemeden Basin. Although origin of the Bida Basin seems related to tectonic activities in adjacent basement areas: South—western Nigeria, and the Younger arenite Province, but with clastic contribution mainly from
the Igneous and Metamorphic basement complex of South—Western Nigeria. An Al1uvial—Fluvial model of deposition is inferred
for the Aranaceoous and Argillaceous units while a shallow marine (lagoon, tidal inlet, or barrier island) environment is inferred for the Ironstone facies probably related to the Tethys transgression into Nigeria during the Tertiary,
Description
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS 1 FOR THE AWARD OF THE MASTER OF SCIENCE IN GEOLOGY
Keywords
STRATIGRAPHY, S E D I M E N T O L O G Y, AREA AROUND BIDA,, NIGER STATE