PALEOENVIRONMENTS AND PROVENANCE OF THE CLASTIC SEDIMENTS OF THE LOKOJA-BASANGE FORMATION, BENIN FLANK OF ANAMBRA BASIN, NIGERIA
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Date
2024-06-30
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The Nexus: Al-Hikmah University, Ilorin, Nigeria (Science Edition)
Abstract
Paleoenvironmental and provenance study of outcropping sediments exposed at different
locations within the Lokoja Basange Formation in the Anambra Basin were investigated to
deduce the transportation history, provenance and paleoenvironments of the sediments.
Successions of the sandstones, siltstones and shales observed along road cut and river
channels were studied to establish their field relationship and characteristics. 11 sandstones
samples were selected and subjected to grain size analyses to determine the graphic mean,
sorting, skewness, and kurtosis while 10 sandstone samples were analyzed by heavy mineral.
Field observation revealed three lithofacies mainly sandstones, siltstones, and shales in the
studied sections. The mean, sorting, skewness, and kurtosis have the following ranges (0.07-
4.3, 0.78 - 2.20, -1.18 - 0.77, and 0.48 -4.92) respectively. The sandstones ranged from finemedium-
coarse grained exhibiting poor sorting. The sandstones were characterized by
angular to sub angular grains having low maturity reflecting short transportation history and
fluvial depositional environments in a low energy setting. Most of the sandstones are finely
skewed and leptokurtic while few samples exhibits very coarse skewed and platykurtic. The
siltstones and shales suggest a coarsening upward progradational pattern and may indicate a
deltaic sedimentation. Heavy mineral assemblages observed in the sandstones include
zircon, rutile, magnetite, topaz, and tourmaline which suggests provenance from igneous and
metamorphic sources from the Precambrian Basement Complex of Nigeria.