Detailed
characterization of the outcropping sediments in the Ikpankwu
and Ihube axis was undertaken to
validate lithostratigraphic
boundaries and nomenclatures which had stirred up debates amongst scholars in recent
times. Stochastic method established dominant facies
associations and preferred stacking patterns, which were used to interpret
environments of deposition (EODs), while foraminiferal and palynological analyses
fingerprinted both paleo depths and age of the sediments. The results
established the dominance of similar lithofacies at the basal parts of both
sections indicating mappable geological units and members of the same
lithostratigraphic unit. The basal lithofacies
are succeeded up section, however, by different lithological
units in both the KM 75 and Ikpankwu sections. Interpretations of EODs using
lithofacies successions predicted fluvial to tidally-influenced shallow
marine deposits, which are environments in close affinity with each other. Interpretations
using abundance and diversity of micro fauna supported non-marine
(coastal-deltaic) to middle neritic paleo-water depths also, typical
of marginal to shallow marine EODs. Recovered
foraminiferal assemblages in the shale samples from the
upper parts of both sections, however, depicted
deposits of Nsukka Formation
despite variations observed in lithofacies assemblages because the identified Haplophragmoides species that populate
the upper units had been used to define the Late Maastrichtian-Paleocene age.
Sediments at the basal parts with mappable lithological units at both sections
were rather populated by species that connote the Campanian-Maastrichtian age
when the Mamu Formation sediments were deposited. Palynomorphs recovered from
both the basal and upper sections also suggested
Campanian-Maastrichtian and Late Maastrichtian-Paleocene age, indicative of
Mamu and Nsukka Formation sediments, respectively.
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