PALYNOFLORAL BIOSTRATIGRAPHY OF WELL AX, ONSHORE NIGER DELTA, NIGERIA

Asadu,  A.N and Onowaro, V. O.

Department of Earth Sciences, Federal university of Petroleum Resources Effurun, Nigeria.

Correspondence e-mail: asadu.anthonia@fupre.edu.ng

Abstract

The Eighty -eight (88) ditch cutting rock samples from Well AX, between interval 5900 feet and 9000 feet were processed for palynomorphs using standard palynological sample processing procedures for their palynofloral contents for the purpose of establishing their biozonation, age and paleoenvironments. Lithologic description of the ditch cutting rock samples reveal that the sediments are mostly made of sandstone, with minor alterations of shale, mudstone, and siltstone as well as accessory minerals at some horizons.  The shale is light grey, unconsolidated, sub fissile to fissile; the sandstone is made up of White to light grey, unconsolidated, well sorted, very fine grained to medium, sub-rounded to sub-angular grains while the mudstone is reddish and unconsolidated. The accessory minerals are pyrite and carbonaceous detritus, characteristically depicting Agbada Formation. Palynological analysis yielded ninety-six (96) well preserved miospores from which three biozones (Belskipollis elegans, Crassoretitriletes vanraadshooveni and Pachydermites diederixi zones were recognised and correlated with P740, P720 and P680 subzones of Evamy et al., 1978, respectively to assign early to middle Miocene age for the sediments. The abundance and diversity of terrestrially derived miospores and rare occurrence of marine derived types guided the interpretation of palaeo-environments in the studied section of the well AX. The sediments revealed fluctuations between continental/marginal marine to near shore/coastal deltaic paleo-environments.

Keywords: Palynomorph, Paleoenvironment, Age, Biozonation, Niger Delta, Palynology.