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Rjeas Research Journal in Engineering and Applied Sciences 2(2) 86-94 Rjeas 

© Emerging Academy Resources (2013) (ISSN: 2276-8467) 

www.emergingresource.org 

SEQUENCE PALYNO-STRATIGRAPHICAL STUDY OF DEL-2 WELL 

SOUTHWEST OF THE NIGER – DELTA BASIN NIGERIA 

1 Ojo, A.O and 2 Gbadamosi, A.O. 

1 Department of Geology, 

Ekiti State University, Ado – Ekiti, Nigeria. 

2 Department of Geology, 

Obafemi Awolowo University, Ile – Ife, Nigeria. 

Corresponding Author: Ojo, A.O 

___________________________________________________________________________ 

The Niger delta is one of the most prolific oil and gas producing Tertiary deltas in the world, yet its 

biotratigraphy is less well understood. Despite the fact that a lot of exploration activities have been carried out in 

the basin, very little information has been published on its microfossils. Most of the information is kept as 

confidential reports in the archives of the oil companies for confidential reasons. Forty ditch-cutting samples 

from Del-2 well in the Southwestern part of the Niger delta basin were studied for their palynomorph content to 

date and deduce the depositional environment of the strata penetrated. A sequence stratigraphic interpretation 

was also attempted for the strata whose depth ranged from 609.60 m – 975.36 m. Of the 88 palyno-species, 60 

pollen grains, 14 spore species and 14 other species made up of dinocysts, acritarchs, and algal cysts were 

identified. Other components of the palynomorphs include charred graminae cuticle, and microforaminiferal 

wall linings. The strata penetrated are dated Early – Late Pliocene based on the occurrence of, 

Racemonocolpites hians, Retistephanocolpites gracilis, Praedapollis obodoensis, Peregrinipollis nigericus, 

Multiareolites formosus; Verrutricolporites rotundiporus and Gemmanocolpites sp. The Early/Late Pliocene 

boundary was put at 710.18m, based on the first occurrence of Gemmanocolpites sp and regular occurrence of 

Retibrevitricolpites obodoensis and R. protudens. Three depositional environments, shallow, deep and open 

marine were deduced based on the relative abundance and diversity of the miospores and marine microfossils. 

The four proposed biozones (A B C and D) were based on the miospore distribution and abundance, especially, 

those of Monoporites annulatus and Zonocostites ramonae. One candidate sequence boundary and three system 

tracts: highstand, transgressive and low stand systems tracts, were deduced to occur within the studied interval. 

A candidate maximum flooding surface (mfs) occurred at 746.7 meters, depth. Thus this study has significantly 

contributed to the data base of published palynoflora records of the Niger delta basin and equally establish 

palynnofacies records and sequence stratigraphy of Pliocenc age of Agbada Formation. This will aid further 

studies in biostratigraphy and correlation of strata within the basin and other basins in the Gulf of Guinea. 

©Emerging Academy Resources 

KEYWORDS: Sequence- Stratigraphy, Palynospecies, Niger – Delta Basin, Monoporites Annulatus, Maximum 

Flooding Surface. 

________________________________________________________________________________________ 

INTRODUCTION 

Forty ditch – cutting samples from a well in the 

southwestern part or the Niger delta basin were 

analyzed in this study. The location and name of the 

well were not made available for propriety reasons; 

consequently, it is hereby designated as Del - 2 well. 

The Niger delta (Fig. 1) is the most significant 

hydrocarbon province on the West African 

continental margin. It lies mainly in the Gulf of 

Guinea to the southwest of the Benue – Trough and 

constitutes the most important Cenozoic deltaic 

construction in the south Atlantic. 

Several methods are applied during exploration to get 

enough information about the well(s) of interest in 

the Niger delta. Such methods include 

sedimentological, biostratigraphical and seismic 

stratigraphic techniques – The biostratigraphical 

techniques applied during exploration in the Niger 

delta are palynology, micropaleontology and 

calcareous Nannoplankton study. 

The application of palynology to stratigraphy, 

paleoecology and correlation began in the 1960s 

(Hopking, 1967) and the demand for palynological 

application in solving other geologic problems has 

been on the increase since then. In the exploration for 

oil, palynology alongside sedimentology, 

paleontology and seismic stratigraphy plays an 

important role. This is as a result of the durability, 

diversity and statistical value of palynomorphs, thus 

their study has contributed significantly to 

biostratigraphy and hydrocarbon exploration. Also, 

the application of sequence stratigraphy to the study 

86

Research Journal in Engineering and Applied Sciences (ISSN: 2276-8467) 2(2):86-94 

Sequence Palyno-Stratigraphical Study Of Del-2 Well Southwest Of The Niger – Delta Basin Nigeria 

of sedimentary rocks has provided a good 

chronostratigraphic model for a more efficient 

exploration and exploitation of hydrocarbons. 

Numerous works have been undertaken on the 

Tertiary Niger delta. Some of the pioneer workers on 

the geology of the Niger delta include Short and 

Stauble (1967) and Frankl & Cordry (1967), who first 

provided the initial information on the sediments and 

subsurface distribution of the stratigraphic units in 

the Niger delta. Short and Stauble, (1967) studied the 

outline of the Niger delta and suggested that the 

major source rocks were shales of the Agbada 

Formation. Some works have also been done by 

Avbovbo (1978) and Oyede (1992) on the 

environment of the Niger delta. Oyede (1992) based 

on palynofacies principle pioneered by Whitaker 

(1985); identified the following environments in the 

Niger delta, mangrove swamp, channel deposits, 

shoreface and marine. 

Palynostratigraphic studies undertaken to date on the 

Niger delta include those of Va-Hoeken – 

Klinkenberg (1964), Germeraad et al. (1968), Knaap 

(1971), Kogbe and Sowumi (1975), Legoux (1978), 

Jan du Chene et al (1978), Jan du Chene and Salami 

(1978), Biffi and Grigani (1983), Morley and 

Richards (1983) Poumot (1989), Oboh, et. al. (1991), 

and Oboh (1992). 

Clarke (1966) identified Peregrinipollis nigericus, as 

a new sporomorph in the Upper Tertiary of southern 

Nigeria subsequently; it has been extensively used as 

middle Miocene marker in the Niger delta. The most 

comprehensive palynological research to date was 

carried out by Germeraad et. al., (1968) on some 

Tertiary sediment from the world’s tropical areas. It 

is largely a comparative study of palynomorphs of 

Tertiary sediments from tropical South America, Asia 

and West Africa. Knaap (1971) provided a good time 

correlation across the continental deposits of the 

Benin Formation and the transitional sequence of the 

Agbada Formation and considered the sudden 

appearance of Podocarpus milanjianus, a montane 

conifer as a time marker. 

Evamy et al. (1978) adopted an informal 

palynological zonation for the Niger delta using alpha 

numeric nomenclature. Legoux (1978) analyzed and 

used Praedapollis africanus, P. flexibilis, 

Verrutricolporites rotundiporus and other taxa for the 

zonation of some parts of the Neogene Niger delta. 

Sowumi (1981) analyzed pollen grains of thirty – six 

meters deep cores from the Niger delta and concluded 

from the report that in the Quaternary, there were 

shifts in the extent of rainforest and that the savannah 

had been reduced. Biffi and Grignani (1983) worked 

on dinoflagellate cysts assemblage that penetrated 

Oligocene strata and they proposed seven new 

species belonging to the Lejeunecysta, two new 

species of the Phelodinium and one new species of 

the Selenopemphix. 

Inspite of all these studies, no work has documented a 

sequence palynostratigraphic study of the 

palynomorphs of the Niger delta sediments, thus this 

study is embarked upon with the aim of carrying out 

a biozonation, datation and paleoenvironmental 

interpretation of the sequence penetrated by Del-2 

well. The information thereon obtained will 

contribute towards better understanding of fossil 

floral diversity of the basin. 

GEOLOGY OF THE STUDY AREA 

The geology of the Niger delta is known through, the 

numerous subsurface data acquired during oil 

prospecting. Part of these data has been published. 

The history and structure are relatively well known 

through several syntheses (Short & Stauble, 1967; 

Hospers, 1971; Murat, 1972; Weber & Daukoru, 

1975 and Whiteman, 1982). 

Generally, it is agreed that the modern Nigeria delta 

is built on an oceanic crust. Argument supporting this 

view comes from the reconstruction of its 

precontinental drift positions (Stoneley, 1966). The 

evidence indicates an important overlap of NE Brazil 

on the present Niger Delta and a series of linear 

subdued and alternating positive ands negative 

anomalies beneath the Niger delta. These anomalies 

have been interpreted by Burke et al (1971) as sea 

floor spreading lineation (Mascle, 1976). 

Three major sedimentation cycles have been 

established in the Niger delta as well as other parts of 

the southern Nigerian sedimentary basin. 

These are: (i) Lower Cretaceous to Santonian cycle 

and 

(ii) Campanian to Paleocene cycle and 

(iii) Paleocene/Lower Early Eocene to 

Recent (Youngest) 

The third sedimentary cycle, which started in the 

Paleocene/Early Eocene, is responsible for the main 

part of the delta’s growth (Short & Stauble, 1967). 

The Niger delta oil province with its commercial oil 

fields is confined to the area covered by a thick 

sequence of rocks belonging to the youngest 

(Tertiary) sedimentary cycle. 

Megatectonically, the Niger delta is framed by a set 

of older and stable megatectonic elements that 

enhanced and controlled the development of the 

present day Niger delta (Fig. 2). Rift faulting during 

the Precambrian developed these structures (Weber, 

1971). Deep-seated faults associated with this rifting 

controlled the outlines of the delta. These structures 

are (i) the Benin flank, a NE – SW trending flexure or 

fault zone called the Benin Hinge Line, (ii) the 

Calabar flank N.W-SE hinge line which is the 

subsurface continuation of the Oban Massif. It marks 

the eastern fringe of the delta, (iii) the Senonian 

Abakaliki uplift and (iv) the post Abakaliki Anambra 

Basin. These units are found to the north of the delta, 

87



and were also stable elements throughout the 

Cenozoic (Fig. 2). 

Stratigraphy 

Since the inception of the Cenozoic delta in the 

Paleocene/Lower Eocene, the history has been one of 

a major regression with a gradual southward offlap of 

thin, quite extensive lenses of sediments formed as 

result of deposition occurring simultaneously under 

full terrestrial (fluviatile) conditions with the 

interplay between terrestial and marine influence (i.e. 

paralic) and under fully marine conditions (Frankl & 

Cordry 1967). Thus the sequence observed laterally 

(i.e. starting with coarse sandy deposits and ending 

with marine clays) is also observed vertically in the 

Niger delta. 

In a cross-section, a time stratigraphic unit of such 

deltaic sediment is characteristically S-shaped or 

sigmoidal (Merki, 1972). The formations are 

therefore strongly diachronous, their ages becoming 

progressively younger in a downdip direction and 

ranging from Paleocene to Recent. Thus the 

established tertiary sequence in the Niger delta 

demonstrates a tripartite lithostratigraphic succession 

(Fig.3) from marine prodeltaic shale (Akata 

Formation) through a sand/shale paralic unit (Agbada 

Formation) to continental sands (Benin Formation). 

The strata compose and estimated 8535 m of the 

section at the approximate depocentre in the central 

part of the delta (Short and Stauble, 1967). The 

characteristic features of these formations are 

outlined below: 

Akata Formation: It is characterized by a uniform 

shale development. The formation is a marine 

sedimentary sequence laid down in front of an 

advancing delta. These prodeltaic shales are medium 

to dark grey, fairly hard or at places soft, gumbo-like 

and sandy or silty in several places, the shales of this 

formation were found to be undercompacted, and 

therefore mobile, and may contain lenses of 

abnormally high-pressured siltstone or fine-grained 

sandstone (Allen, 1965; Reyment, 1965; Short & 

Stauble, 1967 and Oomkens 1974). The upper 

boundary of the formation has been structurally 

deformed, while diaprism and high-pressure zones 

developed in it, on a large scale. 

Generally, the Akata Formation contains rich 

foraminiferal fauna. Planktic foraminifera may 

constitute moiré than 50 % of the microfauna. The 

benthonic foraminiferal assemblages indicate that the 

shale was deposited on a shallow marine shelf and 

slope. The Akata Formation is considered to be the 

main source rock in the Niger delta (Evamy et al, 

1978; Bustin 1988 and Schlumberger, 1985). The 

known age of the Akata Formation is Eocene to 

Recent (Asseez, 1976; Doust and Omatsola 1990). 

The shale is continuous in the subsurface with its 

probable outcrop equivalent the Paleocene/Eocene 

Imo Formation. The complex movements of the 

Niger delta sediments are controlled by the 

adjustments of the shale either by the downward 

movements in response to the pressure impacted by 

the overlying sediments or lateral motion of the shale 

on the continental slope or its upward diapiric 

motion. These movements are believed to have 

assisted in the formation of the growth faults and roll 

over structures, which are common features of the 

main Niger delta basin. 

Its thickness is unknown because most wells drilled 

in the Niger delta did not encounter the base of the 

Akata Formation, except for the northern part of the 

delta where the formation has been drilled into the 

Cretaceous. 

Agbada Formation: This sequence of strata forms 

the hydrocarbon prospective sequence in the Niger 

delta. The formation is characterized by alternating 

sandstones and shales of the delta front, distributary 

channel, and deltaic plain origin. 

Weber (1971) showed that the alternating sequence 

of sandstones and shales of the Agbada Formation is 

of cyclic sequences of marine and fluvial deposits. 

The sand content ranges from 50 to 75 %. The 

sandstones are medium to fine grained, fairly clean 

locally calcareous, and shelly. They consist 

dominantly of quartz and potash feldspar with 

subordinate and illite. The shales are dark to grey, 

fairly consolidated and silty with local glauconite. 

They consist dominantly of kaolinite (average value 

73 %) with small amount of mixed layers of illite and 

montmorillonite. 

The formation has a maximum thickness of 3940 

meters at the central part and thins northwards and 

towards the North western and Eastern flanks of the 

delta. Although, the thickest known section is about 

3480 meters, the maximum thickness may well be 

much greater (Short and Stauble 1967). Generally, 

the boundary between the sand and shales is sharp. 

Where the sands grade into shales, shell fragments, 

glauconites, limonite coatings are common. The 

shales are denser at the base than higher up in the 

column because of compaction. They become silty 

and sandy towards the Benin Formation while 

shaliness increases downwards and laterally into the 

Akata Formation. 

The Agbada shales contain microfauna that are best 

developed at the base of individual shale units. The 

depth of the fossil assemblage ranges from littoral 

estuarine to marsh types of fauna developed at a 

water depth of approximately 100 meters. The 

slightly consolidated sand has a calcareous matrix, 

but most of the sand is unconsolidated. The coarse 

and poorly sorted sand indicates a fluviatile origin 

while the well-sorted sand represents beach or coastal 

barrier deposits. The mature Eocene to Miocene 

shales interbedded within the deltaic sands in the 

lower part of the paralic sequence is considered to be 

88



a major source rock. (Nwachukwu & Chukwura, 

1986; Knox & Omatsola 1989; Shannon & Naylor 

1989: Doust & Omatsola 1990 and Reijers 1996). 

The Agbada Formation is held to contain most of the 

reservoir rocks of the Niger delta. The porosity is of 

excellent quality (ranging between 28 and 32 %) 

while permeability is in the darcies. Reservoir quality 

is closely dependent on the depositional environment. 

The Agbada Formation is less carbonaceous and 

more marine than overlying Benin Formation there is 

also an increase ion microfauna with depth. This 

could be an indication of increasing rate of 

sedimentation and changes in salinity and 

temperature of the delta front. The age of the Agbada 

Formation varies from Eocene to Recent. 

Benin Formation: This is the uppermost unit of the 

Niger delta complex. The formation can be easily 

distinguished based on its high sand percentage (70 – 

1000 %). The sand is dominantly massive highly 

porous and freshwater bearing with locally 

interbedded shale beds, which are considered to be of 

braided stream origin. 

The sands are poorly sorted, ranging from fine to 

coarse – grained and occasionally pebbly and they 

contain abundant wood, fragments, which become 

lignitic with depth. Composition, structure and grain 

size show deposition in a probably upper deltaic 

environment. The thickness is variable and may be 

more than (1990 m) in Warri – Degema area. 

Most companies exploring for oil in the Niger delta, 

arbitrarily define the base of the Benin Formation by 

the deepest fresh - water – bearing sandstone that 

exhibits high resistivity. Short & Stauble (1967), 

however, defined the base of the Benin Formation by 

the first marine foraminifera within shale, as the 

formation is non-marine in origin. Avbovbo (1978) 

partly agrees with Short & Stauble (op cit) but also 

demonstrated that the base of the fresh water in the 

delta sediments extends into the Agbada Formation 

and thus not coincident with the base of the Benin 

Formation. 

The Benin Formation is deposited across the entire 

Niger delta. It is a continental deposit and consists of 

various structures such as natural levees channel fills, 

ox-bow fills etc. these structures indicate a variability 

of the shallow water depositional medium (Short & 

Stauble, 1967). It becomes progressively younger 

from North towards the South. 

Subsurface Clay Members: A clay section in the 

subsurface of the Eastern Niger delta, the “Afam clay 

member” is locally recognized. The member has the 

form of a canyon fill that strikes in a SSE direction, 

from slightly north of Afam – 1 to the west of Imo 

estuary. It also grades southwards into Agbada and 

Akata Formations. The base is difficult to delineate 

where it contains basal sand intercalations and rest on 

the underlying paralic Agbada Formation 

Lithologically; it is laminated and has a maximum 

thickness greater than 8,000 m (Short and Stauble, 

1967; Whiteman 1982; Doust and Omatsola 1990). 

The age ranges from Oligocene to Recent. Other 

subsurface clay members apart from a fan clay 

Member occur in the delta. The other anomalous 

shale bodies have been recognized within the Agbada 

and Benin Formations. The clay bodies within the 

Agbada Formation are the Opuama, Osare, Qua-Iboe 

and Elelenwa, while Makaraba, Soku and Amojie 

clays are members of the Benin Formation. The age 

of these clays; range from Oligocene to Recent. 

MATERIAL AND METHOD OF STUDY 

Forty ditch-cutting samples from Del – 2 well in the 

Niger delta were used for this study. The sample 

depth intervals extend from 609.60 m to 975.36 

meters. The samples were composited. 

The 20 composite samples were subjected to standard 

technique of macerations for the preparation of acid 

insoluble microfossils. 

10 grams of each sample were treated with 10 % 

hydrochloric acid (Hcl), then 40 % hydrofluoric acid 

(HF), 60 % Nitric acid for a period of 3 to 5 minutes, 

2 % Potassium hydroxide (KOH). Separation by Zinc 

chloride ZnC 2 (S.a.2.2) s solution and mounting in 

glycerin jelly. 

Identification and counting of palynomorphs were 

done using a Laborlux 6 (Leitz) light microscope 

using the objective magnifications of 25 and 40. The 

palynomorph species were identified with the aid of 

relevant publications such as Clarke (1966), 

Germeraad et al (1968) Legoux (1978), albums from 

shell, Agip etc. The identification was based on size, 

exine structure, shape, sculptures and aperture type. 

RESULTS 

Analysis of the slides of Del 2 well yielded seventyfour 

palynomorph species. Pollen and spores are 

dominant and the other palynomorphs include a few 

dinoflagellate species, a few acritarchs and 

microforaminiferal linings. There are also charred 

graminae cuticle and a lot of fungal pores (Fig.4). 

The spores recorded belong to the species of 

corruporis, Laevigatosporites, verrucatosprites, 

Leotriletes, Lycopodiumsporites, Anthocerosporis, 

Stereosporites, 

Polypodiaceoisporites, 

Crassoretitriletes Magnastriatites and Retitriletes. 

The pollen taxa recovered are: Zonocostites ramonae, 

Monoporites annulatus, Racemonocolpites hians, 

Retistephanocolpites gracilis, Praedapollis flexibilis, 

Striatricolpites catatumbus, Retibrevitricolporites 

protudens, Pachydermites diederixi, Arecipites sp, 

Psilatricoloporites crasssus, Retitricolporites 

irregularis, Fenestrites spinosus, 

89



Sapotaceoidapollenites sp, Cyperaceaepollis spp 

Echitricolporites, spinosus; obodoensis, 

Nymphaepollis claus, Retibrevitricolporites 

obodoensis, peregrinipollis nigericus, 

Echiperiporites estelae, Gemamonocolpites sp, 

Multiareolites formosus, Echitricolporites 

icacinoides, Verrutricolporites rotundiporus, 

Polyporotetradites laevigatus, Nymphaepollis sp 

Polyadopollerites vacampoae, Psilatricolporites spp; 

Psilatriporites sp., Anthostema aubryanium 

Psitricolpites sp, Nummulipollis neogericus, 

Echimonocolpites minor, E. major Canthicimidites 

reticulates, Triporopetes neogenicus, 

clavainperturopollenites spp. Pandamites 

sp,Crototricolpites crotonoisculptus, Scherosperma 

sp, Psitricolpites operculatus, Elaeis guineensis, 

Ctenolophonodites costatus, Corylopollis avallena 

Retitricolpites sp., Bombacacidites sp. Corsinipollis 

jussiensis, Brevitricolporites guinetti, Polycolpites 

spp., Impatiencidites brevicolpus, Echriletes 

echinatus, Loranthicidites spp, Heterocolpites 

laevigatus, Alnipollis verus and Pinus haploxylon. 

The algal cysts present are: Pediastrum spp, 

Pediastrum bifidites, and Botryococcus branny and 

Concentricytes sp. The dinoflagellate cysts are: 

Selenopemphix nephroides, Lejeuncysta fallax, 

Lejeuncysta sp. Operaulonioduim centrocarpum and 

Nematophaeropsis labyrinthea. The acritarch taxon 

encountered was Leiosphaeridia sp. These forms are 

illustrated in photomicrographs (Fig.5). 

The distribution chart shows the different specimens 

encountered at the different depths interval. The 

different taxa vary in abundance; some are considered 

common while some are relatively rare. 

The common forms are: Striatricolpites catatumbus, 

Retribrevitricolpites protudens Pachydermites 

diederixi, Psilatricolporites crassus, Retitricolpites 

irregularis, Sapotaoladopollenites sp, 

Nymphaeapollis clarus, Retibrevitricolporites 

obodoensis, Peregrinipollis nigericus, Anthostema 

aubryanium, Psilamonocolpites sp., Edumocolpites 

minor, Triporoletes neogenicus, currusporis spp., 

Ployapodiaceoisporites spp., Leotriletes spp., 

Laevigatosporites spp., Stereosporites spp., 

Verrucatosporites spp and Echitricolproites spinosus. 

The rare forms are: Cassoretitriletes 

vanraadshooveni, Magnastriatites howardii, 

Crassoretitriletes spp., Retitriatites spp., Lycopodium 

sporites sp., Echiperiporites estalae, Arecipites sp. 

Pinus haploxylon, Alripollis verus, Heterocolpites 

laevigatus, Loranthacidites spp., Echitriletes 

echinatus, jupatiencidites brevicolpus, polycolpites 

sp., Brevitricolporites guinetti, Corsinipollis 

jussiensis, Psilatricolpites operculatus, 

Bombacacidites sp, Retitricolpites sp., 

Anthoceroporite echinatus, Retistephanocolpites 

gracilis, Racemonocolpites hians Praedapollis 

flexibilis, cyperaceaepollis spp, Multiareolites 

furmosus, Echitricolporites icacinoides, 

Verrutricolpites rotundiporis, Polyporotetradites 

laevigatus, Nympheaepollis sp., Polyadopollenites 

vacampoae, Psilatricolporites spp., Retitriporites sp., 

Nummilipollis concimus, canthiumidites reticulates, 

clavainaperturopollenites spp., pandanites sp., 

crototricolpites crotonoisculpties stereosperma sp., 

Psilatricolpites operculatus, Elaeis guineensis, 

Ctenolophonidites costatus, and Corylopollis 

avallene. 

Age: The studied interval has been dated early 

Pliocene to late Pliocene, based on the presence of 

the following marker species: Racemonocolpites 

hians, Retistephomocolpites gracilis, Praedapollis 

flexibilis, striatricolpites catatumbus, 

Retibrevitricolpites protudens, Pachydermites 

diederixi, Retibreviatricolpites obodensis, 

Psilatricolporites crassus, Retitricolpites irregularis, 

Fenestrites spinosus, Cyperaceaepollis spp., 

Echitricolpoeites spinosus, Nymphaepollis clarus, 

Peregrinipolllis nigericus, Echiperiporites estelae, 

Gemmamonocolpites sp., Multiareolites formosus, 

Echitricolporites icaciboides and Verrutricolporites 

rotundiporis. 

The early/late Pliocene boundary was determined 

based on the first downhole occurrence 

Gemmamonocolpites sp., Multiareolites formosus 

and Echiperiporites icacinoides. Besides there is the 

regular occurrences of Retibrevicolporites protudens 

and R. obodoensis, abundance of Pereginipollis 

nigericus and sparse occurrence of Praedapolis 

flexibilis across the boundary were distinctive 

(Legoux 1978, Poumot 1989). 

However, other fossils of different ages occur within 

the studied interval, such as Heterocolpites 

laevigatus, Retitricolpites irregularis, 

Psilamonocolpites sp and Loranthacidites sp. They 

are probably reworked specimens because most of 

them are not well preserved, or probably due to 

contamination during sample processing. 

Biozonation: Four informal biozones were derived 

within the studied interval. These sub-zones have 

been termed subzone A, sub-zone B, subzone C and 

subzone D, following stratigraphic procedures. 

Subzone A. This zone ranges from a depth of 865.63 

m to 975.36 m. An abundance of Monoporites 

annulatus, low occurrence of Zonocostites ramonae 

and a minimum recovery of spores characterize it. 

Other diagnostic features in this zone are the first 

down hole occurrence of Pinus haploxylon, 

Alnipollenites verus, Heterocolpites laevigatus, 

Crassoretitriletes vanraadshooveni, Echitricolporites 

icacinoides and Verrutricolporites rotundiporus. 

There is also a sparse occurrence of Arecipites sp., 

Corrusporis sp., Nymphaepolis clarus, 

Peregrinipollis nigericus, Echiperiporites estelae, 

90



Psilatricolporites sp., Nummulipollis neogenicus, 

Edimonolcopites minor, Canthiumidites reticulates, 

Edimonocolpites major Triporoletes neogenicus and 

Crototricolpites crotonoisculptus. 

The sparse to common recovery of 

Retibrevitricolponites obodoensis and 

Brevitricoloprites guinetti was observed within this 

interval coupled with the low occurrence of 

Sapotacaeoidepollenites sp, Cyperaceaepollis spp. 

Psilamonocolpites sp., Leotriletes adriensis and 

Polypodiaceoisporites spp. 

Top: Last downhole occurrence of the assemblage 

constituted by Retibrevitricoporites protudens and 

Crototricolpites crotonoisculptus at the depth of 

865.63m 

Base: Undefined. It is here, taken as the base of the 

studied interval 975.36 meters. 

Age: Early Pliocene. 

Subzone B: This zone ranges from 755.90 in to 

865.63m depth of the studied interval. It is 

characterized by an appreciable recovery of 

Zonocostites ramonae a low recovery of Monoporites 

annulatus and a considerable amount of spores. The 

sparse occurrence of Praedapollis flexibillis, 

Striatricolpites catatumbus, Echitricolpites spinosus, 

Pachydermites diederixi Echitricolporites 

icacinoides, Cathiumidites reticulates, 

Crototricolpites crotonoisculptus, Psilatricolpites 

operculatus, Elaeis guineensis and Brevitricolporites 

guinetti was also observed within this interval. 

In addition, there was a low recovery of 

Psilatricolpites crassus, Retibrevicolporites 

irregularis, stereosporites sp. and heoisphaeridia sp. 

This zone also has the common occurrences of 

Retibrevitricolporites 

protudens, 

Sapotacaeoidapollenites sp, Peregrinipollis 

nigericus, Anthostema aubryanium Verrucatosporites 

sp, fungal spores and microforaminiferal wall lining. 

Top: The top of this zone occurs at a depth of 

755.90m. It is marked by the first appearance of 

Polycolpites sp., Impatiencidites brevicolpus, and 

Echitriletes echinatus, and by the last appearance of 

Lycopodiumsporites sp and Crassoretitriletes sp. 

Base: The base corresponds to the top of subzone A. 

i.e. 865.63m 

Age: Early Pliocene. 

Sub-zone C: This subzone ranges from a depth of 

664.46m to 755.90m depths and is characterized by a 

low recovery of Zonocostites ramonae. The 

abundance of Monoporites annulatus also decreased, 

while spores are generally reduced in abundance. 

Other diagnostic feature of this subzone is the first 

down hole occurrence of Peregnnipollis nigericus, 

Gemmamonocolpites sp., Multiareolites formosus, 

Ctenolophoridites costatus, Crototricolpites 

crotonoisculptus, Retitricolpites sp., Bombacacidites 

sp., Cornsinopollis jussiensis, Brevitricoloporites 

guinetti, Retritriletes sp., Magnastriatites howardii. 

The common occurrences of Retibrevitricolporites 

protudens, Nymphae clarus, Retitricolporites 

obodoensis, Peregrinipollis nigericus, Leotriletes sp., 

and Stereosporites sp were also observed. Low 

recovery of Arecipites sp., Retitricolporites 

irregularis, Sapotacaeoidapollenites sp, 

Cyperaceaepollis sp., Gemmamonocolpites sp., 

Psilamonocolpites sp., Ploypodiaceoisporites spp., 

Psilamonocolpites sp., Polypodiaceoisprites spp., and 

the sparse to common occurrence of Striatricolpites 

catatumbus, Echitricolpites sp., Canthiumidites 

reticulatus, Brevitricolporites guninett; Lycopodium 

sp., Lejeunecysta sp and Pediastrum sp are additional 

characteristics of this biozone. 

Top: The top of the zone is marked by the first 

appearance of Echiperiporites estelae and 

Ctehonophonoides costatus, at 664.46 m. 

Base: The base coincides with the top of the biozone 

B at 755.90m. 

Age: Late Pliocene to early Pliocene. 

Sub zone –D: This zone occurs within the interval of 

609.60 m to 664. 46 m depth. Characteristics features 

of this zone are the peak occurrence of Monoporite 

annulatus, a low recovery of Zonocostites ramonae 

and an appreciable recovery of spores. 

This zone is very rich is occurrence of 

Retistephanocolpites gracilis, Retitricolpiotes 

irregularis, Cyperaceaepollis sp., Psilamonocolpites 

sp., Edimonocolpites minor, Elaeis guineensis, 

Crassoretitriletes sp. and Currusporis sp. The sparse 

occurrence of Striatricolpites catatumbus, 

Anthostema aubryanium, Psilatricolpites sp. 

Nummulipollis neogenicus, Echimonocolpites major, 

Triporoletes neogenicus, Polypodiaceoisporites spp, 

Leotriletes sp., Laevigatosporites sp., Stereoporites 

sp., Verrucatosporites sp., microforaminiferal wall 

lining, fungal spore, Pediastrum sp and Oisphaeridia 

sp. 

Low occurrence of Arecipites sp., 

Sapotaceoidapollenites sp., Retribrevitricoporites 

obodoensis, Canthiumidites reticulatus were also 

recorded. The rare/sparse occurrence of Sclerosperma 

sp., Selenophempix nephroides, Racemonocolpites 

lians, Anthocerosporites echinatus, Praedopollis 

flexibilis, Retibrevitriolporites protudens, 

Pachydermites diederixi, Psilatricolporites crassus 

and Echitricolpites spinosus were recorded in this 

biozone. 

91



Top: This is undefined but it is assumed to coincide 

with the top of the studied interval at 609.60 m. 

Base: The base coincides with the top of sub-zone C 

at 664.46 m 

Age: Late Pliocene age. 

Sequence Stratigraphy 

The sequence stratigraphic interpretation of the 

interval (609.60 m – 975.36 m) in Del-2 well is based 

on the abundance and diversity of the marine 

microfossils and the relative abundance and diversity 

of the miospores. 

Four sequence boundaries were delineated at the 

following depths 701.04 m, 774.19 m, 865.63 m and 

902. 21 m. Three system tracts, the lowstand 

(LST),Transgressive (TST) and the highstand (HST) 

systems tracts are represented. 

The highstand system tract is interpreted to have 

formed during the later part of the relative rise of sea 

level when the rate of relative sea level was 

decreasing. The rate of sea level rise decreases during 

the development of high stand systems tract. (Vail, 

1987). It is characterized by intervals of coarsening 

and shallowing upwards. 

In the studied sections, the HST is present within the 

depth interval of 701.04 m – 774.19 m. It is 

characterized by the peak occurrence and diversity of 

the marine microfossils (Fig.6). 

The trangressive systems tract is (TST) a systems 

tract found between the highstand (HST) and the 

lowstand (LST) is identified within the depth 

intervals 609.60 m –701.04 m; 774.19 m-847.34m 

and 902.21 m – 975.36 m. brackish environment 

developed in protected coastal plains during the TST 

are characterized by low diversity assemblages of 

low salinity tolerant plants and animal species. This 

is very evident at the intervals listed above. 

The lowstand systems tract (LST), the 

stratigraphically oldest systems tract in a sequence 

that is usually deposited during an interval of sea 

level fall at the offlap break and subsequent slow 

relative sea level rise (Emery and Myers, 1999) is 

encountered within the interval 85.7.34 m to 902.21 

m. “The LST is recognized most importantly in the 

proximal fossil record by an underlying hiatus, a 

sudden shallowing up of biofacies or the super 

imposition of non-marine assemblages on marine 

ones”. 

CONCLUSION AND RECOMMENDATIONS 

There are certain limitations which have prevented a 

high resolution of the biozones, age and 

paleoenvironmental deductions established in Del-2 

well, these include among others: (i) the limited 

number of composited samples to the uppermost 

section of the well, (ii) the inability of identifying 

some of the retrieved fossils to species levels due to 

lack of accessibility to archives of exploration 

companies and thier contradictory zonation schemes 

prevented the definition of upper and lower 

boundaries of Pliocene age in Del-2 well. 

However, in conclusion, Del –2 well is characterized 

by eighty-eight palynomorph species, which include 

spores, pollen, dinocysts, algal cysts and acritarchs, 

fungal spores, microforaminiferal wall linings and 

charred gramineae cuticle were also identified. 

Based on the presence of some selected marked 

species, the studied interval was dated Early Pliocene 

to Late Pliocene and the boundary between the two 

epochs was placed at the depth of 701.04 m. In 

addition, the biozonation and paleoenvironmental 

determination of the Del-2 well was done using the 

relative abundance and diversity of miospore 

assemblages and the marine microfossils. Four 

biozones (informally designated biozones A, B, C 

and D) and three depositional environments; shallow, 

deep and open marine environments were 

established. 

The sequence stratigraphy of the well was attempted 

based on the relative abundance and distribution of 

the marine microfossils and miospores. Four 

sequence boundaries (at 701.04m 774.19 m, 847.34 

m and 902.50 m) were established. Three systems 

tracts, High stand systems tract (HST) (701.04 – 774, 

19 m and 865.63 m – 902.21 a transgressive systems 

tract (TST) (609.60 m – 701.04 m; 774.19 –847.34 

m) and a lowstand systems tract (LST) 902.21m – 

975.36 m were also identified. 

It is hereby recommended that the section below the 

studied part should also be studied and that the 

seismic stratigraphic study of the whole well should 

also be undertaken. This will give a better picture of 

the strata penetrated by by the well. It will also help 

in identifying all the reservoirs in the strata. 

Thus, an integrated study that combines sequence 

stratigraphy with palynostratigraphy should be used 

in erecting standard biozonation, age and 

paleoenvironmental scheme for the Niger delta basin. 

ACKNOWLEDGEMENT 

The authors wish to express their sincere thanks and 

appreciation to Professor M. O. Odebode of Obafemi 

Awolowo University, Ile – Ife, Nigeria for the 

initiation and supervision of this project. S.A. 

Akinyemi and D. Omagba helped in the computer 

graphics of this project The comments of the 

anonymous reviewer is highly appreciated too. 

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