Investigation of the Foraminiferal Biostratigraphy of Well AMKP 2-11 in Shallow, Offshore Niger Delta Basin, Nigeria

Abstract

The objective of this paper was to investigate the foraminiferal biostratigraphy of well AMKP 2-11 (interval 3280m to 4629m), in shallow, offshore of the Niger Delta Basin, Nigeria using appropriate standard procedures with 135 ditch cutting samples analysed at 60m. 40 foram species were recovered including Cylammina minima, C. cancellata, Saccamina complanata, Haplophragmoides narivaensis, H. compressa, H. obliquecameratus, Ammobaculites strathearnensis, Valvulina flexilis, Recurvoides deformis. One foram biozone N17 was identified and characterised by top occurrences of Cyclammina minima and Saccamina complanata at 3390m and top occurrence of Haplophragmoides narivaensis at 4130m. The occurrence of Haplophragmoides narivaensis, Globigerinoides extremus and influx of agglutinated taxa in the studied section of the well enabled an inference of Late Miocene (Messinian) age. The paleoenvironment of deposition is identified as Upper Continental Shelf to Mid Continental Shelf environments based on the occurrence of the Inner Neritic biofacies such as Lenticulina inornata, Heterolepa pseudoungeri and Ammobaculites spp. as well as deep water middle to outer shelfal foraminiferal assemblages, such as Cyclammina minima, Haplophragmoides compressa, Vavulina flexilis, Trochammina globigeriniformis, Uvigerina peregrina of the Middle Neritic. Therefore, a Middle Neritic (Middle Continental Shelf) environment (40–100 m) was inferred due to the presence of very fine-grained clay signifying slow rate of deposition of taxa as well as distinctive benthonic foraminiferal assemblage: Cyclammina minima, C. cancellata, Saccammina complanata, Uvigerina subperegrina, Vavulina flexilis, Karreriella siphonella. This work provides detailed the biostratigraphic framework of the well section.

Keywords

• Foraminifera; Biostratigraphy; Chronostratigraphic surfaces; Paleoenvironment; Biozone