FORAMINIFERAL ANALYSIS AND PALEOENVIRONMENTS OF SEDIMENTS IN WELL -AA, DEEPWATER OFFSHORE, NIGER DELTA, NIGERIA.

ENAMEKERE UMOH EKAETE, OLUWASEYI FASINA PEACE

Abstract


Foraminiferal analysis was carried out on twenty five (25) ditch cutting samples from well -AA, offsore Niger Delta
covering a depth interval of 9000ft-11025f. The study was aimed at age deduction, zoning the well, and interpreting
the paleoenvironment of deposition. Lithostratigraphic description carried out on the sample revealed that the bulk
lithofacies constitute shale with streaks of sand (fine-medium) between 9170ft - 9210ft and 9360ft -9380ft. The entire
analysed interval was barren of planktonic foraminifera while depth 9960ft revealed a spot occurrence of Lagena spp,
representing the only calcareous benthic foraminifera recovered in the entire interval. Few to common occurrences of
deepwater agglutinated foraminifera were found in the well, dominated by some species of Haplophragmoides spp
and Haplophragmoides narivaensis. Other foraminifera with rare and scattered occurrence includes, Cribrostomides
spp, Bathysiphon spp, Troahammina spp, Cyclammina spp, Cyclammina cancellata, Valvulina spp, and Glomospira
spp. The only microfaunal associated accessory recovered is ostracod at depth 1080ft. The analysed intervals was
assigned a Middle – Late Miocene (N17 and older age) based on the FDO of Haplophragmoides narivaensis. The
environment of deposition is based on the distribution of typical deep water arenaeceous foraminifera species
recovered in the study. The predominance of the arenaeceous forms over calcareous forms suggest outer shelf
environment of deposition.


Keywords


Foraminifera, Palaeoenvironment, Niger delta, Biostratigraphy.

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