integrated biostratigraphic study of well etankpini 005 ... · pdf filemaceration techniques...

International Journal of Scientific & Engineering Research, Volume 6, Issue 3, March-2015 1129 ISSN 2229-5518

• IJSER © 2015 • http://www.ijser.org

———————————————— • Aniediobong Jonah UKPONG (Ph.D) is currently a

lecturer in the department of Geology, University of Calabar, Cross River state, Nigeria. +2348033189441. [email protected] .

• Ogie Macaulay EKHALIALU (B.Sc) is pursuing a masters degree in petroleum geosciences (Micropaleontology) +2348062110426. [email protected]

Integrated Biostratigraphic Study of Well Etankpini 005(ET005) based on Foraminiferal

and Palynological Analysis, Calabar Flank; South Eastern Nigeria.

By

A.J Ukpong, and O.M.Ekhalialu

Abstract : The Cretaceous formations penetrated by well ET005, Etankpini, Calabar Flank, consist of a sequence of dark grey fissile fossiliferous shales (the Ekenkpon Formation) at the base and greyish, fine grain ooilitic marl (the New Netim Formation) at the top. The upper greyish, fine grain ooilitic marl suggests a paralic condition in a shallow marine environment. The shallow marginal marine environment is further supported by the high diversity of terrestrially derived palynomorphs such as Polyporisporites spp, Selaginella myosurus and low values of sub-order Classopollis. A major transgression deposited the dark grey fissile fossiliferous shales during the Late Cenomanian-Early Turonian times and the rich planktonic faunal assemblages encountered at certain levels indicate continuous deposition in an open marine environment (Middle neritic and outer neritic environments). Cenomanain-Early Turonain age is assigned to the sediments penetrated by well ET005 and this is supported by the co-occurrences of Classopollis spp, Classopollis classoides, Classopollis jardinei, Triorites africaensis, Cretaceiporites mulleri, Triffosapollenites rugosa and Steevesipollenites binodosus (palynoflora) as well as the co-occurrences of Hedbergella crassa, Hedbergella planispira, Heterohelix moremani, Heterohelix reussi and Globigerinelloides caseyi(microfauna).

Index terms: Age, Cretaceous, Ekenkpon Formation, Foraminifera, New Netim Formation, Paleoenvironment, Palynomorphs,

+2348033189441 +2348062110426

1. INTRODUCTION Foraminifera are protozoa which occur in a variety of brackish and marine environments, from coastal to deep areas. They are generally abundant and respond quickly to environmental changes. When foraminiferal analysis is combined with palynological analysis (integrated biostratigraphy), micropaleontologist can easily undertake age determination and paleoenvironmental studies of a formation. This work adopted this approach in identifying the planktonic and benthonic foraminiferal species as well as palynomorphs in Well ET005 in order to establish the age(s),predict paleobathymetry and ancient depositional environment(s) of the Cretaceous rock sequences penetrated by this well. The obtained result compared favorably with the existing stratigraphy of the Calabar Flank. Well ET005 is situated at Longtitude N621582 and Latitude E732112 in

Etankpini, Calabar Flank, South Eastern Nigeria (fig. 1)

1.1 GEOLOGIC SETTING AND STRATIGRAPHY OF THE CALABAR FLANK

The term Calabar Flank was first introduced by [1], as part of the Southern Nigeria sedimentary basin that is bounded by the Oban Massif to the North and the Calabar hinge line delineating the Niger Delta Basin in the South [2]. It is also separated from the Ikpe platform to the West by a NE-SW trending fault. In the East, it extends up to the Cameroun Volcanic ridge. It served as the gateway to all marine transgression into the Benue trough and is located between two hydrocarbon provinces, the Tertiary Niger Delta and the Cretaceous Douala basin in Cameroun [3].

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Fig 1: Geologic Map of the Calabar Flank showing location of the well ET005

Structurally, the Calabar Flank consists of basements horsts and grabens that aligned in a NW-SE direction like other South Atlantic (fig. 2) marginal basin in West Africa [3]. The Calabar Flank shows striking stratigraphic similarities with other coeval marginal basin of the South Atlantic Ocean. Sedimentation started in the Calabar Flank with the deposition of fluvio-deltaic clastics (the Awi Sandstone) of

probably Aptain age on the Precambrian crystalline basement complex, the Oban Massif. This was followed by the first marine transgression in the Mid Albian which account for the deposition of the Mfamosing Limestone, particularly on the horst and relatively stable platform areas and their flanks.

Fig. 2: Structural elements of the Calabar Flank and adjacent areas (after Nyong and Ramanathan, 1985){2]

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The Mfamosing Limestone is overlain by the thick sequence of black to grey shale unit, the Ekenkpon Formation[3]. The formation is characterized by minor intercalation of marls; calcerous mudstone and oysters beds. This shale unit was deposited during the late Cenomarian-Turonian times. The Ekenkpon Shale is overlain by a thick marl unit; the New Netim Marl [4]. This unit is nodular and shaly at the base and is interbedded with thin layer of shales in the upper section. Foraminefera [2] suggest early Coniacian age for this marl unit. The New Netim marl is unconformably overlain by carbonaceous dark grey shale, the Nkporo formation [5]. The shale unit was deposited during the late Campanian-Maastrictian times. The Nkporo Shale caps the Cretaceous sequence in the Calabar Flank. The Nkporo Shale sequence is overlain by a pebbly sandstone unit of the Tertiary Benin Formation.

1.2 LITERATURE REVIEW OF THE CALABAR FLANK

Earliest biostratigraphic studies of the Calabar Flank were conducted by [5]and [6a]. [5] used ammonites to assign a Cenomanian age to the lower part and a Turonian age to the upper part of the Odukpani type section. The Cenomanian age assigned to the lower Limestone (Mfamosing Limestone) at Odukpani was later supported by [6b] and [7]using foraminiferal evidence. Fayose ,1979 [7] already pointed out that the basal arenaceous member of the Odukpani Formation is both petrologically and structurally correlatable with Mamfe Formation of Albian age. The Mfamosing Limestone was however dated more accurately as Albian age using ammonites [8] and foraminifera [9], [10]. Nair et al, 1981[9] found that the Mfamosing Limestone is devoid of foraminifera but pointed out that the overlying shale contains

Late Albian to Earliest Cenomanian planktonic foraminifera assemblage. Hence, they asserted that the underlying limestone is not younger than Late Albian.

Fayose ,1979[7] working on the carbonate/shale sequence of the Eze-Aku Shales, exposed at the Nkalagu Limestone quarry in the Lower Benue Trough, found abundant species of Heterohelix and Hedbergella suborder and some ostracodes such as Brachycythere, Ovocytheridea and Paracypris which gave a Lower Turonian age. Petters ,1982[10] also, used Hedbergella planispira; Heterohelix moremani; Guembelitria harrisi and Praebulimina fang assemblages found in the Nkalagu Formation to assign a Turonian age to the Eze-Aku Shales. This agrees with the Early Turonian ammonite age given by [5].

Odebode and Skarby ,1980[11] carried out foraminifera studies of outcrop samples along Calabar- Itu highway and established Santonian - Campanian age for the lower part of the Nkporo Shale using the species of the suborder Rugoglobigerina, Heterohelix, Ventilabrella, Globotruncana and Gabonita. However, more accurate dating for the Nkporo shale was presented by [2] and [12] who used species of Heterohelix reussi, Globotruncana fornicata, G. trincaniata and Rugoglobigerina sp. to assign Late Campanian age for the lower part of the Nkporo Shale, while the upper part was dated Maestrichtian based on the presence of Bolivina afra, Gabonita elongata, Gabonita lata and Praebulimina bantu. The Maestrichtian age agrees with the works of [5] and [10]which depended on ammonite and foraminifera assemblages respectively. Fig. 3 shows different views as presented by various workers on the ages of Cretaceous sediments in the Calabar Flank

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Fig. 3. Different views on the ages of Cretaceous sediments in the Calabar Flank (After Adegbie and Bassey,2007)[24]

2. METHODOLOGY 2.1 Micropaleontology

Samples for foraminifera studies were collected at 5m interval from core samples obtained from well ET005 drilled to a depth of 42.12m. These samples were later composited at 10m interval. Each sample was prepared in the laboratory following the standard procedures for foraminifera sample preparation as outlined by [13] and [14]. The identification of the foraminifera was done by comparing picked forms with previously published forms using a binocular microscope. Quantitative analysis was done using the number of species count per sample to establish diversity and abundance of forms.

2.2 Palynology The obtained core samples were also analyzed for palynomorphs. Samples preparation was by the usual maceration techniques for acid insoluble microfossils which includes dissolution of carbonates and silicate using hydrochloric acid and hydrofluoric acid. 40% concentrated Nitric acid (HNO3) (for oxidation of humic matter) and 1%

Potassium hydroxide (KOH) for acid neutralization and dissolution of humic matter. Concentration was by sieving using 200 and 400 mesh nylon screens and pipetting the organic residue from a watch glass. Slides of temporary strew mounts using glycerin jelly was made for each of the samples. Transmitted light microscope was used for studying the palynomorphs. The palynomorphs were counted and recorded. Analysis was done by comparison with published work to identify the various forms of palynomorphs. 3. RESULTS AND DISCUSSION 3.1 Lithostratigraphy

Two distinct lithologic units were recognized in the sampled section of well ET005 consisting of about 20m of greyish fine grained oolitic marl overlying thick (17.12m) dark grey fissile fossiliferous shales at the base and capped by a 5m thick dark brownish clayey laterite. These rock units compared favourably with some of the stratigraphic units of the Calabar Flank (the New Netim Marl and the Ekenkpon Shale) outlined by Adeleye and Fayose (1978), Nyong (1995) and Essien et al (2005). The Lithostratigraphy of well ET005 is presented in Fig 4

Depth (m) Lithology Lithological Description Formation 0-5 - ∴ - -

- - -

Dark brownish clayey laterite

5-25

Greyish; fine grain oolitic Marl

New Netim Marl

25-42.12

Dark grey fissile Fosiliferous shale

Ekenkpon Shale

Fig. 4: Lithostratigraphy of sediment penetrated by well ET005

.

. . -

- .

. .

.

.

.

.

. .

. . . .

. .

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3.2 Foraminiferal biostratigraphy The analysed samples yielded a total of sixteen (16) foraminifera species comprising both planktonic (14) and benthonic (2) species.

The lower section of the study well yielded more planktonic foraminiferal forms than the middle and upper sections

which were characterized by some barren intervals. The planktonic forms are dominated by long-ranging fauna of the (Hedbergella crassa, Heterohelix moremani, Heterohelix reussi, Hedbergella planispira), However some of the encountered forms (Globigerinoides caseyi) also have restricted stratigraphic range.

The biostratigraphic range chart of foraminiferal species, depth of occurrence and their counts are presented in fig. 5

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Fig 5: Foraminiferal range chart( chart 1)

Well Name : ETWell Code : ET-OBInterval : 0m - 42m FORAMINIFERAL DISTRIBUTION / STRATIGRAPHIC OF ET- 005Scale : 1:750

Depth

5m

10m

15m

20m

25m

30m

35m

40m

Ch

ron

ost

rati

gra

ph

y

0

42

Ce

no

ma

nia

n-

Ea

rly

Tu

ron

ian

Ag

e

- Occurrences ofHedbergella crassa, H.planispira,Globigerinelloidescaseyi, Heterohelixmoremani & H. reussiwithin the interval

Foram Event Samples

Bar

ren

*1

Ha

plo

ph

rag

mo

ide

ssp

p

Am

mo

ba

culit

es

spp

10.00m CU

20.00m CU

30.00m CU 2

40.00m CU 2242.12m CU 9 1

Foraminifera AgglutinatingAbsolute abundance (20mm=35 counts)

Glo

big

eri

ne

lloid

es

case

yiH

ed

be

rge

llacr

ass

a

He

db

erg

ella

pla

nis

pir

a

He

db

erg

ella

sim

plic

issi

ma

He

db

erg

ella

spp

He

tero

he

lixm

ore

ma

ni

He

tero

he

lixre

uss

i

Cla

vih

ed

be

rge

llasi

mp

lex

Cla

vih

ed

be

rge

llasp

p.

Cla

vih

ed

be

rge

llasu

bcr

eta

cea

Glo

big

eri

na

spp

Gu

em

be

litri

ah

arr

isi

He

db

erg

ella

de

lrio

en

sis

He

db

erg

ella

sig

ali

2 10 6 1 6 17 5

39 28 2 33 31 1 4 2 1 3 3 2

2 37 17 4 21 32 2

Foraminifera Planktonic*2

Ga

stro

po

ds

spp

Ost

raco

ds

spp

1 2

12

2

MM

Tota

lco

un

t:F

ora

min

ifera

150

49

173126

Foraminifera

Div

ers

ity:F

ora

min

ifera

15

8

1410

Foraminifera

Tota

lco

un

t:F

ora

min

ifera

Pla

nkt

on

ic

150

47

149115

FOP

Div

ers

ity:F

ora

min

ifera

Pla

nkt

on

ic

15

7

127

FOP Palaeoenvironment Foram Version

Non

-M

arin

e

Mid

dle

Neri

tic

Ou

ter

Ne

ritic

FORAMINIFERAL DISTRIBUTION/STRATIGRAPHIC CHART OF WELL ET-005

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Age determination using Foraminifera is carried out on the basis of Last Appearance Datum (LAD) or First Downhole Occurrence (FDO) and First Appearance Datum (FAD) or Last Downhole Occurrence (LDO) of index forms.

The Cenomanain-Turonain age is assigned to well ET005 on the basis of planktonic index forms; Hedbergella crassa, Heterohelix moremani, Heterohelix reussi, Hedbergella planispira and Globigerinoides caseyi.

The planktonic species: Hedbergella delrioensis, Hedbergella planispira, Hedbergella spp were initially described from Cenomanian sediments in the Ituk-2 Well[7]. Sediments of Turonian age were also recognized on the basis of the occurrence of Heterohelix reussi, Heterohelix moremani, Heterohelix simplicissima and Globigerinelloides caseyi. [10]. Similar assemblages have been reported by Fayose (1979), on the

Turonian sediments in Ituk-2 well, and [10] from road-cut samples of the Eze-Aku Shales at km 24.8 on the Calabar-Itu highway. The presence of species belonging to Heterohelix genera which are mainly restricted to Turonian age and Hedbergella genera which are mostly Cenomanian forms further confirms this age. Essein and Edoho, 2012 [18] also reported similar assemblages from the New Netim Marl.

3.3 Palynostratigraphy The core samples yielded spores, palmae and associated elements like dinoflagellate, chitinous microforaminifera test linings and other undiffferented spores and pollen.. The biostratigraphic range chart of palynomorphs species, depth of occurrence and their counts is presented in fig. 6

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Occurrences of Trioritesafricaensis, Classopollisspp, C. classoides, C.jardinei, Cretaceiporitesmulleri, Elaterosporitesklaszi, Steevesipollenitesbinodosus &Triffosapollenites rugosawithin the interval

Paly Event

Absolute abundance (15mm=20 counts)

Ep

he

dri

pite

sm

ultic

osta

tus

Ep

he

dri

pite

ssp

p.

Cla

sso

po

llis

cla

sso

ide

s

Cla

sso

po

llis

jard

ine

i

Cla

sso

po

llis

ma

jor

Cla

sso

po

llis

mija

wkin

ea

eC

lasso

po

llis

sp

p

Co

mp

lexio

po

lle

nite

ssp

p

Cre

tace

ipo

rite

sm

ulle

ri

Cre

tace

ipo

rite

sp

oly

go

na

lis

Ela

tero

sp

ori

tes

kla

szi

Ela

tero

sp

ori

tes

sp

Ep

he

dri

pite

sja

nso

nii

Ep

he

dri

pite

sp

roce

rus

Ste

eve

sip

olle

nite

sg

iga

nte

us

Tri

fossa

po

lle

nite

sru

go

sa

Tri

ori

tes

afr

ica

en

sis

Cir

cu

lin

ap

arv

us

Cla

sso

po

llis

an

nu

latu

sE

ph

ed

rip

ite

sa

mp

ho

rip

ho

rmis

Ge

mm

atr

ile

tes

cla

va

tus

Re

ticu

latisp

ori

tes

jard

inu

sS

tee

ve

sip

olle

nite

sb

ino

do

su

sS

tee

vis

ipo

lle

nite

sm

ultilin

ea

tus

Ste

evis

ipo

lle

nite

sn

ative

nsis

Cla

sso

po

llis

tod

osu

s

Ela

tero

plicite

sa

fric

ae

nsis

Ep

he

dri

pite

ssp

ira

les

1 2

5 2 35 8 3 68 6 8 1 2 1 3 4 1 1 46

126 4 343 8 24 2 1 9 1 273 7 2 1 1 2 3 2 1

18 48 4 430 12 45 6 6 10 1 333 2 6 2 1

Markers

Samples

Barr

en

Absolute abundance (15mm=20 counts)

La

evig

ato

sp

ori

tes

ova

tus

Le

iotr

ile

tes

sp

p

Se

lag

ine

lla

myo

su

rus

Sm

oo

thm

on

ole

tesp

ore

Po

lyp

ori

sp

ori

tes

sp

p

Cic

atr

ico

sis

po

rite

ssp

p.

De

lto

ido

sp

ora

sp

pC

ya

thid

ite

ssp

p.

De

lto

ido

sp

ora

me

so

zo

ica

Tri

pla

no

sp

ori

tes

sin

uo

su

sV

err

uca

tosp

ori

tes

pa

rvu

sp

se

ud

ose

co

nd

us

Gle

ich

en

idite

sse

no

nic

us

La

evig

ato

sp

ort

ite

ssp

pR

eticu

latisp

ori

tes

sp

p.

10.00m CU 1 1 46 3

20.00m CU 35

30.00m CU 1 7 10 1 3

40.00m CU 3 2 2 1 2

42.12m CU 14 3 8 14 1 1 1 1

SporesAbsolute abundance (15mm=20 counts)

Re

titr

ico

lpo

rite

ssp

p.

Re

titr

ipo

rite

ssp

p.

Ca

ryca

rsp

pC

lasso

po

llis

an

nu

latu

sIn

de

term

ina

tep

olle

nR

etitr

ico

lpite

ssp

p.

Str

iatr

ico

lpite

ssp

p.

Syn

co

lpo

rite

ssp

p

Syn

co

lpo

rite

ssu

btilis

Aq

uila

po

lle

nite

ssp

pE

ch

ipe

rip

ori

tes

sp

pE

ph

ed

rip

ite

sm

ultic

osta

tus

Ep

he

dri

pite

ssp

p

Mo

no

co

lpo

po

lle

nite

ssp

he

roid

ite

s.

Mu

ltip

oro

po

lle

nite

ssp

pP

sila

ste

ph

an

oco

lpite

ssp

p.

Psila

tric

olp

ite

ssp

p.

Re

titr

ico

lpite

so

joe

nsis

Ve

rru

tric

olp

ori

tes

sp

p

2 1

1 1 1 1 2 1 4

1 2 7 1 1 9 4 1 3 4 1 34 2 1 10 6 5 1 6 5 1 1

Undifferentiated*1

Pro

xa

pe

rtite

ssp

pP

sila

mo

no

co

lpite

ssp

p.

Psila

trip

ori

tes

sp

p

2 1 1

4

1

Palmae*1

Re

tim

on

oco

lpite

ssp

p.

1

PO

R

*2

Din

ocystin

de

t.

Din

og

ym

niu

msp

p.

Cri

bro

pe

rid

iniu

msp

p

Cri

bro

pe

rid

iniu

mte

nu

ita

bu

latu

m

Lin

go

lod

iniu

msp

p

2

1

5 1

13 7 5 1

Dinoflagellates*2

Fo

ram

inife

rallin

ing

276

352

89

MRF

To

talco

un

t:S

po

res

50

51

35

22

1043

Spores

To

talco

un

t:P

alm

ae

20

4

4

1

Palmae

To

talco

un

t:M

ari

ne

Ind

ica

tor

Pa

lyn

om

orp

hs

20

278

352

94

1530

MR

PALYNOSTRATIGRAPHIC DISTRIBUTION OF ET-005

Base Lithology

Lithology Qualifiers

Lithology AccessoriesIGD Boundary Key

PossibleProbableConfidentUnconformable

? ?Unconformable

f Fault

?f ?Fault

Text Keys*1 Absolute abundance (15mm=10 counts)*2 Absolute abundance (15mm=20 counts)

Chart Key

Fig. 6 Palynomorphs range chart

PALYNOSTRATIGRAPHIC DISTRIBUTION CHART OF WELL ET-005

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The study section yielded wide age diagnostic palynomorphs namely Ephedripites sp, E. procerus, E. multicostatus, Complexiopollenites sp, Steevesipollenites gigantus and Trifossapollenites rugosa. All these forms are used as Cretaceous marker from Albian- Cenomanain[19] but the co-occurences of Triorites africaensis, Classopollis spp, Classopollis classoides, Classopollis jardinei, Cretaceipirites mulleri, Triffosapollenites rugosa and Steevesipollenites binodosus points solely to Cenomanian- Early Turonain for the study well(well ET005). Similar species have already been recorded in Nigeria by [20]

The top occurrence of diagnostic palynoflora such as Triffosapollites rugosa recorded at 30m in this study have been used to represent Cenomanian in West Africa [19]. Essein and Ufot, 2010[21] also reported this palynoflora in Calabar Flank.

3.4 Paleoenvironmental studies

The distribution of any particular fossil assemblage in any stratigraphic section may be controlled either by paleoecological factors or as a result of evolution [22]. Any changes in fossil assemblages that correspond with lithology is probably due to environmental tolerance of the fossil species rather than to evolution. Some fossils serve as environmental indicators and are used to interpret ancient environment of deposition of sediments. Studies of modern foraminiferal ecology have provided criteria for the reconstruction of marine paleoenvironments. Foraminifera are also in many respects ideal zonal indices for ancient marine rocks.

Based on the biostratigraphic boundaries recognized and the lithostratigraphic studies, the Cretaceous sediments recovered are grouped into two formations which are correlatable with

depositional environments. They are the New Netim Marl and Ekenkpon Shale.

The application of palynological data to paleoenvironmental reconstruction can give reliable inference on the paleoenvironment condition. In this study, the relative abundance of terrestrially derived pollen and spore and marine derived dinoflagellates together with foram test lining as well as the suborder Classopollis were used to interpret the depositional environments of the studied interval. The decrease in pollen grains with distance from the shore [19] was also taken into consideration.

The techniques of Planktonic/Benthonic (P/B) ratio which has been used by many micropaleontologist to determine water depth in marine environment [10] and [7] was also considered in this study. The Planktonic/Bethonic foraminiferal (P/B) ratio in the study well ranged from 0-100% and attempts were made to interpret the ancient environments based on this. The use of foraminiferal (P/B) ratio together with palynological considerations greatly enhanced the paleoenvironmental interpretation of well ET005.

The samples of New Netim Marl were barren of foraminifera. This suggests a protected, paralic and occasionally open shallow marine depositional environment. This is supported further by the dominance of terrestially derived palynomorphs (Selaginella myosurus, Smooth monolete spore , Polyporisporites spp)and minor inclusions of sub order Classopollis as well as dinoflagallates and foraminiferal lining.The greyish fine grained oolitic marl was deposited at the beginning of the regressive phase which began in the Early Turonain immediately after the shale deposition.

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The Ekenkpon Shale shows low arenaceous species and a dominance of Heterohelix and Hedbergella faunal, probably due to deep water paleoecologic conditions (open ocean). This open ocean setting is further supported by the dominance of planktonic species and dinoflagallates as well as foraminiferal test

lining with high inclusion of suborder Classopollis. The dark grey fissile fossiliferous shale was deposited at the beginning of the Cenomanain- Early Turonain Transgression.

Fig. 7 shows the age and lithostratigrahic summary as well as the depositional environment and sea level curve for well ET005

Age Depth (m)

Lithology Lithological Description

Formation Depositional Environment

Relative Sea Level Changes

Fall Rise

0-5 - ∴---…. - -

..--- -

- .--. - ….

Dark

brownish

clayey laterite

Non marine

5-25 . Greyish; fine

grain oolitic

Marl

Dark grey

fissile

Fosiliferous

shale

New

Netim

Marl

Shallow

marine

25-42.12

Ekenkpon

Shale

Open marine

(inner -

middle

neritic)

Figure7: Age, lithostratigraphic summary, depositional environment and sea level curve for well ET 005 (interval 0-42.12m)

Foraminiferal types (Agglutinating and calcerous planktonic) found also enhanced in the interpretation of the paleoenvironment.

According to Miller et al, 1982[23] low Oxygen, low pH and more corrosive bottom waters favour the development of Agglutinating

-.. . ….

. -

- - - -

.

.

.

.

.

Ceno

man

ian

– Ea

rly T

uron

ain

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benthic forms and complete absence of calcerous benthic which suggest total oxygen-deficient bottom conditions during deposition. On this basis, the Agglutinating foraminifera forms (Ammobacullites spp and Haplophragmiodes ssp) found in well ET005 suggest deposition in an oxygen-deficient environment as well as low salinities.

4. CONCLUSION

Well ET005 (interval 0-42.12m) located in Etankpini, Calabar Flank was studied for its sedimentological and biostatigraphic (micropaleontological and palynological) content. The studied interval penetrated a lateritic layer as well as marl and shale lithologic units. These lithologic units belong to the New Netim Marl and the Ekenkpon Shale respectively of the Calabar Flank. Biostratigraphic results reveal a fairly high abundant and low diversity of foraminiferal species together with high abundant and diversity of Palynomorph. The integration of these results enable the assignment of a Cenomanian to Early-Turonian age to the study well. This was made possible by the presence of the following pollen and spores: Classopollis jardinei, Ephedripites procerus, Elaterosporitessp and Steevesipollenites sp and foraminifera: Hedbergella crassa, H.planispira, Heterohelix moremani, H. reussi. The upper marl unit (New Netim Marl) suggests a paralic condition in a shallow marine environment while the lower shale unit (Ekpenkpon Shale) suggests an open ocean of great depth. This inference was based on the environmentally significant foraminiferal taxa and palynomorph recovered from well ET005. The lithostratigraphy of the studied section of well ET005 is in conformity with the stratigraphy of the surface rocks exposed in the Calabar Flank.

ACKNOWLEDGMENT

The authors are grateful to Geology department, University of Calabar, Cross River State, Nigeria and South Sea Petroleum consultants, Port Harcourt, Rivers State, Nigeria. Mr Mike Oshundebe is also appreciated for providing the study samples.

REFERENCES

[1] R.C Murat, ”Stratigraphy and paleogeography of Cretaceous and lower Tertiary in southern Nigeria,” In Africa Geology, Proc. Conf: on Africa Geology. University Press Ibadan, pp 251-266,1972.

[2] E.E Nyong and R.M Ramanthan,”A record of oxygen deficient paleoenvironments in the Cretaceous of the Calabar Flank, SE Nigeria,”. Journal of African Earth Sciences, 3(4), pp 445-460,1985.

[3] S.W. Petters and T.J.A Reijers ,” Cretaceous carbonates on the Calabar Flank,”. In : G. Matheis and H. Schandelmeser(Editors ), Current Research in African Earth Sciences. Balkema, Rotterdam, pp. 155-158,1987.

[4] S.W Petter, E.E. Nyong, E.B Akpan, and N.U. Essien ,” Lithostratigraphic tension of the Calabar Flank, South Eastern Nigeria,” Proceedings of the 31st Annual conference of the Nigeria mining and geosciences society,1995.

[5] R.A. Reyment,”Aspect of the Geology of Nigeria,”. University press, Ibadan, Nigeria, 145p,1965.

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[6a] T.F.J Dessauvagie,“Preservation of Trocholina(Foraminiferida) in the limestone of the Odukpani Formation in Eastern Nigeria,”Journal of Mining geology and metallurgy society, 2(2), pp 57-64,1965.

[6b] T.F.J Dessauvagie, T.F.J, ”Cenomanian Trochalinas from Nigeria, ”. Micropaleontology. 14(1), 64-72,1968.

[7] E.A Fayose,” Cretaceous microfauna from Ituk-2 well Calabar Cross River state of Nigeria,”Bulletin de L’Institute Fondamental d’Afrique Noire. T.40 Serie A, 40, PP. 469-479,1979.

[8] R. Forster and G. Scholz,“ Salaziceras nigerianum .sp from Southern Atlantic in late Albian times. Neues Jb. Geology, Paleontology and Mining.(2)2, 109-119,1979.

[9] K.M. Nair, R.M. Ramanathan and Ukpong,”Sedimentology and Sstratigraphy of the Cretaceous carbonates and associated rocks of Calabar Flank, Nigeria,”journal of mining and Geology, vol 18,pp 120-129,1981.

[10] S.W.Petters,”Central West African Cretaceous-Tertiary benthic foraminifera and stratigraphy,” palaeontographica, Vol.179A, PP. 1-104. [11] M.O Odebode and A. Skarby,” Anadnesporites (Salvinacea) from The Cretaceous of Nigeria,”. GRANA, Vol.19 pp 17-209,1980.

[11] M.O. Odebode and A. Sharby, ”Anadnesporites(Salvinacea) from The Cretaceous of Nigeria

[12] K.P.K Kumaran and R.M. Ramanathan , ”An upper Cretaceous assemblages from The Nkopro Shale of the Calabar Flank,” Journal of paleontological Society of India, Vol 31 pp 9-15,1886. [14] H.A Armstrong and M.D. Brasier,,” Microfossils,” Blackwell Publishing Ltd, Oxford, UK. Pp 274-275,2005.

[13] M.D. Brasier,” Microfossils,”George Allen and Unwin, London. 139pp,1980.

[15] D.R Adeleye,.R and E.A Fayose,” Stratigraphy of the type section of Awi Formation, Odukpani Area, South-Eastern Nigeria,” Nigeria Journal of Mining Geology. 15(1) 35-37,1978.

[16] E.E Nyong,” Cretaceous sediments in the Calabar Flank in the geological excursion guidebook,”. Proceedings of the 31st Annual conference of the Nigeria mining and geosciences society. (14-23), Calabar. March,1995.

[17] N.U Essein, E.J Ukpabio,E.E. Nyong, and K.A Ibe, ”Preliminary organic geochemical appraisals of Cretaceous rock units in the Calabar Flank, Southern Nigeria,” Journal of mining and geology, 41(2) 185-191,2005.

[18] N.U.Essien and B.D. Edoho ,” Lithostratigraphy, microfossils succession ,sequence stratigraphic and depositional environment of the New Netim Formation, Calabar Flank Southern eastern,” International journal of Basic and Applied Sciencess.12(4) 6-19,2012.

[19] S. Jardine and L. Magloire, "Paleontology

and stratigraphy of Cretaceous basins

of Senegal and Côte Ivore." Memories

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Office Recerche Geologiee Minere. (32) 1,

187 -245.1965.

S. Jardine and L. Magloire,” Palynologieet Stratigraphie du Cretace des basins du Senegal et de Cote d’Ivore, ” . Memoirs de Bureau du Recerche Geologiee Minere.(32) 1, 187-245,1965.

[20] R.Jan Du Chene,I. De Klasz and E.E Archibong,”Biostratigraphic study of borehole Ojo-1, SW Nigeria, with special emphasis on the Cretaceous microflora,” Review of micropaleontology. 21(3) 123-139,1978.

[21] N.U Essien and D.O Ufot,“Age of Mfamosing limestone Calabar Flank South Eastern, Nigeria,” International Journal of Basic and Applied sciences 10(05),8-19,2005.

[22] H. Hamza,N.G Obaje and E.O Obioso,”Foraminiferal assemblage and paleoenvironment of Fika shale,” Journal of mining and Geology,38(1)45-55,2002.

[23] A.A Miller,D.B. Lmscoh and F. Mediolo,” Evphiduim excavatum (Terguem) Ecophemotypic versus Subspecific variation,” journal of foremen feral Research,12,116-144,1992.

[24] A.T Adegbie and C.E Bassey,” Cretaceous foraminiferal biostratigraphy and paleoecology of ikono-1 well, Calabar Flank, Southern, Nigeria,”Journal of Mining and Geology, vol 43(1). Pp 31-4,2007.

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