Foraminiferal Assemblage and Palaeoenvironment: A Case Study of Meren 31 Side Tract -2 Well, Offshore Niger Delta

Abstract

A total of one hundred and thirty seven (137) ditch cutting samples retrieved from a well in shallow offshore western Niger delta were composited to sixty-nine (69) and analyzed to determine the microfossils that characterized and for environmental reconstruction of that portion of the Niger delta. Twenty-two (22) benthonic species aside the indeterminate benthos were found in the interval studied. Prominent among them are the following calcareous species: Lenticulina inornata, Quinqueloculina microcostata, Quinqueloculina Lamarckiana, Heterolepa floridana, Heterolepa. pseudoungeriana, Marginulina costata, Cibicides spp., Amphicoryna scalaris caudata, Lagena spp., and Lagena striata. The arenaceous forms identified include Ammobaculites spp., Haplophragmoides sp., Alveolophragmium crassum, Cyclammina spp. and Poritextularia panamensis. Deep water species identified include Verneuillina sp., Karrerialla spp., and Karreriella siphonella. Two informal benthonic zones were proposed for the interval, which also falls within Agbada Formation. They are Heterolepa Pseudoungeriana Informal Zone (1507 m – 1945 m) and    Lenticulina Inornata Informal Zone (2420 m– 2758 m) suggesting the depth range studied to be deposited during Early to middle Miocene. The sediments were deposited within inner to middle neritic environment, inner neritic environment and coastal deltaic environments.

Keywords:  Benthonic, Agbada Formation, Heterolepa Pseudoungeriana, Lenticulina Inornata, paleodepth.