Vol.5, No.11, 1165-1182 (2013) Natural Science
http://dx.doi.org/10.4236/ns.2013.511143
Microbiostratigraphy, microfacies and sequence
stratigraphy of upper cretaceous and paleogene
sediments, Hendijan oilfield, Northwest of Persian
Gulf, Iran
Bahman Soleimani1, Alireza Bahadori1*, Fanwei Meng2
1Department of Geology, Faculty of Earth Sciences, Shahid Chamran University, Ahvaz, Iran;
*Corresponding Author:
2State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sci-
ences, Nanjing, China
Received 30 July 2013; revised 30 August 2013; accepted 7 September 2013
Copyright © 2013 Bahman Soleimani et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Hendijan oilfield is located on Northwest of Pe-
sian Gulf offshore of Iran and geologically in the
Dezful embayment. In this study, the paleo-
sedimentary depositional environment of the
Early Cenomanian to Late Eocene deposits of
the Sarvak, Ilam, Gurpi, Pabdeh and Jahrum-
Pabdeh Formations was evaluated using micro-
biostratigraphy, microfacies and D-INPEFA cur-
ves which are an accurate method in sequence
stratigraphy in terms of regression and trans-
gression of the sea. Also, we used limited ele-
mental geochemical data of oxygen and carbon
isotopes in compare with palaeontological data
to infer the upper part, 10 m, of the Sarvak For-
mation. Statistical correlation analyses of geo-
chemical data from upper part of the Sarvak
Formation enable inference of differences in
paleoconditions at this part and Sarvak Forma-
tion, and another Formation, Ilam, was distin-
guished. Palaentilogical analysis using plank-
tonic foraminifera and calcareous nannofossils
enables inference about time scale of each For-
mation. Petrographic data and different sedi-
ment textures support those inferences resulted
from Gamma ray logs as D-INPEFA curves about
different paleo-conditions that occurred during
the development of the studied Formations.
Synthesis of the analyses leads to the final in-
terpretation that upper Cretaceous, Sarvak, Ilam
and Gurpi Formations, at the Hendijan oil field
were formed in a carbonate ramp that was likely
closed to the open sea, where Gurpi Formation
was deposited, by a shallow barrier that allowed
seawater recharge into the basin and deep ma-
rine basin where Paleogene sediments, Pabdeh
and Jahrum-Pabdeh, were deposited.
Keyw ords: Upper Cretaceous; Paleogene;
Planktonic For a m in i fera; Microfacies ; S equence
Stratigraphy; Hendijan Oil Field (SW I ran)
1. INTRODUCTION
The Persian Gulf Basin is elongate, margin sag-inte-
rior sag, sedimentary basin spanning the last 650 Ma
along the northeastern subducting margin of the Arabian
Plate and is the largest basin with active salt tectonism in
the world. This basin is asymmetrical in NE-SW cross
section with sediments thickening from 4500 m near the
Arabian Shield to 18,000 m beside the Main Zagros Re-
verse Fault. In fact, this basin is situated in the offshore
area of Zagros Fold Belt [1]. It is the richest region of the
World in terms of hydrocarbon resources and Persian
Gulf’s oil fields are among the best oil fields in the
worlds. Oil fields such as Sorush, Hendijan, Bahregansar ,
Nowruz and Lavan are the most important Iranian oil
fields located at the Persian Gulf. According to different
estimates, the basin contains 55% to 68% of recoverable
oil reservoirs and more than 40% of gas reservoirs [2].
The basin is located at the junction of the Arabian Shield
and Iranian continen tal block that belong to two different
(Arabian and Eurasian) lithospheric plates. Collision of
these plates at the Mesozoic/Cenozoic boundary pro-
duced the Zag ros Fold Belt extending for abou t 2000 km

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1166
from southeastern Turkey through northern Syria and
Iraq to western and southern Iran, and with its numerous
supergiant hydrocarbon fields, there are the most re-
source-prolific fold-thrust belt of the world and the large
Mesopotamian Foredeep, which is a member of the Per-
sian Gulf Basin [3]. During the most part of the Phan-
erozoic, this basin belonged to an ancient passive margin
of Gondwana, which was opened toward the Paleotethys
Ocean in the Paleozoic and toward the Neotethys in the
Mesozoic. Stable subsidence and the unique land-scape-
climatic conditions favored the accumulation of very
thick sediments [4] (Figure 1).
Sarvak Formation is a thick carbonated unit deposited
in Neothetys Southern Margin of Zagros area. In the past
this rock unit was called Hipporite limestone, Rudist
limestone and Leshtegan limestone, but with sectional
measurement in Sarvak rock unit at Bangestan Mountain,
Sarvak Formation substituted former names [5]. Based
on identified fossils, the age of the Sarvak Formation is
considered Upper Albin to Turonian in type section. This
formation mostly includes carbon ate in litho logy and was
composed from sequence of thin to medium-bedded
limestone and massive limestone. The lower lithostrati-
graphic limit of Sarvak Formation which is conformable
and gradational overlies the Kazhdumi Formation in type
section. Upper lithostratigraphic limit of that is secant
with Ilam or in some places with Gurpi Formation. Also
Sarvak Formation is one of the most important hydro-
carbon resources produ ction horizons in Iran [6].
The Ilam Formation (Santonian to Campanian), which
is part of the Bangestan Group, mainly consists of fossi
liferous limestone [7]. The type section of the Ilam For-
mation is situated in the Kabirkoh area, Lurestan, and is
overlain by the Surgah Formation and underlain by the
Gurpi Formation [5].
However, in the Hendijan oil field conformable with
and without any recognizab le boundary, the Ilam Forma-
tion, overlying the Sarvak Formation, is locally unre-
vealed. This formation is determined with its 190 meter
thickness of light gray clay limestone which has became
white in effect of weathering, its regular bedding sur-
faces and some thin shale layers be tween the limestone s.
Gurpi Formation developed in Fold Zagross in Prov-
inces Khuzestan, Lorestan and Fars. Age sediment was
reported in restricts stage of santonian to maastichtian.
The name of this formation was derived of Kuh-e-Gurpi
in province Khuzestan, in local type section in north
square oil Lali in north-east Masjed-Soleiman composed
of 320 m argillaceous limestone, with shale and gray
marl tending to blue. The Gurpi Formation overlies the
Ilam Formation and is disconformably overlain by the
Pabdeh Formation [5].
Pabdeh Formation as one of the oil source rocks in
Zagros has drawn the attention of most geologists since a
long time ago. The name of Pabdeh Formation (Paleo-
cene to Early Miocene) is obtained from Pabdeh Moun-
tain in Khuzestan Province where James and Wynd [7]
described the type section at Tang-e Pabdeh in south east
of Pabdeh Mountain wh ich is located in north of Lali oil
field. The formation is known in outcrop and in subsur-
face in the provinces of Khuzestan, Fars and Lurestan of
Iran. Thickness of this Formation in type section is 79 8.5
m. Pabdeh Formation overlies Gurpi Formation discon-
formably and it contains purple shale, shales and clay
limestones, clay limestones with ch erty nodules and dark
shales [5].
The type section of Jahrum Formation is chosen in the
kuh-e-Jahrum which is located near the Jahrum town in
the South of Shiraz [5]. The lowest lithostratigraphic
limit of the Jahrum Formation overlays the Sachun For-
mation and it underlays in Asmari Formation succession
with an erosional disconformity. Based on James and
Figure 1. Mesozoic-Cenozoic stratigraphy correlation chart of the Iranian Sector of the Zagros basin showing the
lateral lithology and facies changes (adapted from James and Wynd [7]).

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182 1167
Wynd [7] studies, the age of the Jahrum Formation is
Late Paleocene to Middle Eocene [8]. This Formation
mainly consists of shale, marl and interbeds of shales and
clay limestones. This Formation is overlain by the As-
mari Formation.
The present study uses biostratigraphic evid ence of th e
Cretaceous (Sarvak, Ilam and Gurpi Formations) and
also Paleogene (Pabdeh and Jahrum-Pabdeh Formations)
of Iran to understand the accurate biostratigraphic boun-
daries, unconformities and depositional facies of the
relevant Formations. In addition, the geochemical evi-
dence was used to determine the boundary between the
Ilam and Sarvak Formations which are difficult to place
due to similar lithologies in these Formations.
2. STUDY AREA
The Hendijan oil field is located in the north-west
section of the Persian Gulf in offshore of Iran, south west
of Iran, and geologically in the Dezful embayment (Fig-
ure 2). It is about 10 km north-east of Bahregansar, 34
km south-west of Tangu and 42 km south-west of Rag-e-
Sefid oilfields. This oil field was discovered in 1968
when the first well was drilled. This oil field is producing
oil from 3 different reservoirs. The Sarvak Formation
part of Bangestan group is considered as one of the
richest petroleum reservoirs of Iran at this oil field. The
structure of this oil field was influenced by two fault
systems.
3. MATERIALS AND METHODS
3.1. Sample Collection
The biostratigraphy of well# 10 at the Hendijan oil
field was investigated using calcareous nannofossils and
planktonic foraminifera by means of samples collected,
one by one, in distances and intervals of 50 centimeters.
For nannofossils investigations, smear slides of 40 sam-
ples from the well# 10 were prepared using a small piece
of sediment and a drop of distilled water. The sediment
Figure 2. (A) Location map of the Hendijan oil field; (B) Main structural elements of subdivisions of the
Zagros province, one of the eight geologic provinces of Iran (adapted from Farzipour-Saein [9]). Showing the
lateral lithology and facies changes (adapted from James and Wynd [7]).

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1168
was smeared onto a glass slide and fixed with canada
balsam and then examined under the light microscope.
For the foraminifer’s investigation, in this study, more
than two hundred samples were examined in thin section:
75 from Sarvak and Ilam Formations, 35 from Gurpi
Formation and 110 from Pabdeh and Jahrum-Pabdeh
Formations. Samples were disintegrated with hydrogen
peroxide and washed over 63 - 150 - 300 - 600 mm
sieves. The 150 mm and 300 mm size fractions were
richest in planktonic foraminifera for biostratigraphic
investigation. Foraminiferal assemblages were checked
qualitatively. Additionally, some sections were investi-
gated for microfacies. However, not all could be used for
biostratigraphic zonations because of bad preservation or
a low foraminifer’s numbers.
3.2. Samples Analysis
The The distribution of planktonic foraminifera is
given in separate figures. Th e biostratigraphic interpreta-
tion resulting from the composition of the planktonic
foraminifera and calcareous nannofossils assemblages
respectively follows the zonal scheme of James and
Wynd [7] and Sissing h [10].
Also charts of sea level changes in well# 10 were il-
lustrated by means of Gamma ray logs and Cyclo Log
3.2 software. Using CycloLog in well analysis and well
correlations is unique in its approach. It uses of a data-
driven analysis of well data, followed by a model-driven
interpretation using the state-of-the-art stratigraphic
conceptual models. Data-driven analysis of wireline log
data, especially Gamma Ray logs, in CycloLog is a
mathematical calculation using spectral analysis. The
results are two types of log transform curves, the PEFA
and INPEFA curves, which are unique to CycloLog.
PEFA shows the relative amount of change between one
data-point and the next, based on the information in a
window of analysis. INPEFA is the integral of PEFA. It
is a cumulative plot of the changes found in the PEFA
curve used to define real (bounding) surfaces and trends
in well zonations and correlations. Interpretation of IN-
PEFA curves usually requires experimenting with the
depth interval over which INPEFA is calculated called
Dynamic-INP E FA (D -I n pefa).
In order to determine the accurate stratigraphic
boundary between Sarvak and Ilam Formations in this
study ten powdered samples collected near significant
biostratigraphic and to some extent lithological changes,
the probable bo undary, were analysed with a Micromass,
Model 602 ES, for oxygen and carbon isotopes at the
Nanjing Institute of Geology and Paleontology, Chinese
Academy of Sciences, Nanjing, China. Fifteen mg of
powdered samples were allowed to react with anhydrous
phosphoric acid in reaction tubes under vacuum at 25˚C
for 24 h. The CO2 extract from each sample was ana-
lyzed for δ18O and δ13C by mass spectrometry. Preci-
sion of data is ±0.1‰ for both δ18O and δ13C and these
values were reported relative to PDB.
4. RESULTS AND DISCUSSION
4.1. Sarvak and Ilam Formations
4.1.1. Biostratigraphy of Sarvak Fm.
Biozones d etermined by James & Wind [7] for Zagros
region of Iran are consisted of 66 biozones. These bio-
zones are based on the appearance of different planktonic
foraminifera at the stratigraphic column of Zagros For-
mation with age range of Triassic to Pliocene.
The thickness of Sarvak Formation is varied from 90
to 115 meters at the Hendijan wells. In these wells Sar-
vak Formation is overlain by the Ilam Formation un-
comfortably determined in this study. It is underlain the
Kazhdumi Formation with conformable contact. In this
oil field, Sarvak Formation has been formed of marly
limestone and dolomnite with thinner interbeds of marl
and limestone. Out of this, 18 genera and 26 species
were determined (Figure 3). Based on the obtained fo-
raminifera, in the studied section, Saevak Formation is
Early Cenomanian to Turoninan in age that correspond-
ing to Favusella washitensis acro zone (23), Oligoste-
gina facies (26, 26b) biozones of James & wind [7].
Principal index planktonic foraminifers, identified
based on James and Wynd [7], Alegret & Thomas [11],
Gibson [12], khosrotehrani [13], Loeblich & Tappan [14]
within the Sarvak Formation at this oil field, are as be-
low:
Biticinella berggiensis, Calcisphaerula innominata,
Dicarinella primitive, Dicarinella canaliculata, Favu-
sella washitensis, Globigerinelloides algeriana, Globig-
erinelloides sp., Globig erinelloides ferreolensis, Hedber-
gella delroiensis, Hedbergella planispira, Hedbergella
sp., Heterohelix reussi, Heterohelix sp., Lenticulina sp.,
oligosteginids, Praeglobotruncana sp., Rotalipora Cush-
mani, Rudist fragment, Stomiosphaera sphaerica (Figure
4).
4.1.2. Introducing Biozonation of Sarvak Fm.
Actually, in the studied stratigraphic section, consid-
ering microbiostratigraphic studies three biozones have
been determined for identified foraminifers in the sedi-
ments of the Sarvak Formation which are as follow:
1) Biozone No. 1—Favusella washitensis acro zone
(23) [7]: The thickness of this biozone at the beginning
of the Sarvak Formation in Hendijan Section is 12.5 m
(from depth 3039.5 to 3052 m) and its microfossils in-
clude: Favusella washitensis, Hedbergella delroiensis,
Hedbergella planispira, Lenticulina sp., Oligosteginid,
Which indicates the age of Albian to Early Cenomanian.
2) Biozone No. 2—Oligostegina facies (26) [7]: This
biozone determined in the middle of the Sarvak Forma-

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Figure 3. Stratigraphic column, Planktonic foraminiferal distribution and sequence stratigraphy of the Sarvak and Ilam Formations
rom the Well# 10 at the Hendijan oil field.
f

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1170
Figure 4. All figures in PPL light micrographs at 200× magni-
fication; 1. Globigerinelloides ferreolensis; 2. Heterohelix
reussi; 3. Hedbergella planispira; 4. Hedbergella sp.; 5. Biti-
cinella berggiensis; 6. Favusella washitensis; 7,8. S tomios-
phaera sphaerica; 9. Dicarinella canaliculata; 10. Rotalipora
Cushmani; 11. Rudist fragment; 12,13. Lenticulina sp.; 14,15.
Oligosteginid; 16. Globigerinelloides ferreolensis.
tion includes the sediments of Middle to Late Cenoma-
nian. The thickness of this biozone is 55 m (from depth
2984.5 to 3039.5 m) and its organic constituents includes:
Oligosteginids, Favusella washitensis, Hedbergella del-
roiensis, Hedbergella planispira, Lenticulina sp., Rudist
fragment, Praeglobotruncana sp.
3) Biozone No. 3—Sub zone Oligostegina facies (26-b)
[7]: This biozone includes Turionian sediments in the
studied stratigraphic section of the Sarvak Formation.
The thickness of this biozone is 27 m (from depth 2957.5
to 2984.5 m) and its microfossils include: Calcisphaerula
innominata, Dicarinella primitive, Dicarinella canalicu-
lata, Heterohelix reussi, Globigerinelloides ultramicra. It
should be considered that as the subzone Oligostegina
facies (26-a) of late Cenomanian age is absent, it can be
inferred that Late Cenomanian sediments are missing
due to an unconformity at the beginning of this biozone.
So, the uppermost interv al of the Sarvak Formation, with
thickness of nearly 27 m, appears to be deposited after
the time of this unconformity.
4.1.3. Biostratigraphy of the Ilam Fm.
Because the Rotalia sp.-algae assemblage zone (30)
and the Globotruncana concavata-Globotruncana ventri-
cosa carinata assemblage zone (32) of James and Wynd
[7] cannot be recogn ized within the Sarvak Formation, it
can be inferred that a major unconformity occurred dur-
ing the Coniacian to Santonian. Based on the index
planktonic foraminifers such as Globigerinelloides ul-
tramicra, Globotruncana ventricosa, Globotruncanita
elevata, Globotruncana arca, Hedbergalla holmdelensis,
Hetrohelix striata, Pseudotextularia elegans (Figure 4)
that are identified between the depth of 2947 to 2957.5 m,
in marly limestone interbedded with thin layers of lime-
stone and shale, the biozone Globotruncanita elevata
elevata zone (33) of James and Wynd [7] can be recog-
nized. This biozone with thickness of 10.5 m includes all
sediments of Early Campanian age in the studied strati-
graphic section of the Hendijan oil field considered as
Ilam Formation (Figure 3).
4.1.4. Recognition of Boundary Between Ilam
and Sarvak Fms. Using Geochemical
Analysis (Ox ygen and Carbon Isotopes)
Due to their similar lithology, the recognition of the
exact boundary between the Ilam and Sarvak Formations
in the study area is difficult, and it is not possible to de-
termine the precise boundary between these two Forma-
tions based only on biostratigraphy. The carbon and
oxygen isotopes compositions of Ilam and Sarvak For-
mations were used to determine the exact boundary.
Mean δ18O values for the Sarvak Formation (−3.5‰
PDB) are distinctly lighter than mean δ18O values of the
Ilam Formation (−2.7‰ PDB). Thus, this difference can
be used to recognize the boundary between the Ilam and
Sar vak F ormations within the stratigraphic succession [9]
(Figure 5).
In a similar way, δ13C values can also be used for the
recognition of the stratigraphic boundary between the
two formations [15]. All carbon isotope values are posi-
tive in the Ilam Formation, in contrast to negative δ13C
values in the Sarvak Formation (Figure 5(B)). The C-O
isotope data indicate clearly that this is due to subae-
Figure 5. (A) Variation of δ18O along the stratigraphic column
of Ilam and Sarvak Formations; (B) Variation of δ13C along the
stratigraphic column of the Ilam and Sarvak Formations. Note
that the oxygen and carbon isotope data indicate that Ilam car-
bonates have stabilized in the marine phreatic environment,
while the negative δ13C values of Sarvak Formation indicate a
subaerial exposure surface, below which meteoric diagenesis
influenced the upper few metres of the Sarvak Formation.

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182 1171
rial exposure in which meteoric diagenesis affected (at
least) the upper few meters of the Sarvak Formation
[10,11].
The least-altered carbonate sample, with a δ18O value
of −2.4‰ PDB, was used to calculate a temperature dur-
ing the relatively shallow burial, using the equation of
Anderson and Arthur [16]:
 
2
CW CW
TC164.14()0.13    
where T is temperature (in ˚C), δC is the heaviest oxygen
isotope value in the studied samples and δW is the oxygen
isotope value of marine water in the Cretaceous (in
SMOW), i.e. −1‰ SMOW [9]. This calculation gives an
early shallow burial fluid temperature of about 24˚C.
The δ18O values in the Ilam limestone range from
−2.4‰ to −2.95‰ PDB (mean −2.7‰ PDB), whereas
δ13C values range from 0.8‰ to 2.3‰ PDB (mean 1.5‰
PDB). The δ18O-δ13C values from the Ilam Formation
suggest diagenetic alteration in a marine phreatic setting
(Figure 6).
By and large, it can be clearly inferred from the de-
termined boundary near the top of the Sarvak Formation
using foraminifera and geochemistry that about 10 m of
strata assigned to the upper part of Sarvak Formation
where it is overlain by Gurpi Formation is definitely Ilam
Formation instead. This has caused many problems dur-
ing well drilling.
4.1.5. Sequence S tra tigraphic Description of
Sarvak Fm. in Well# 10 of Hendijan Oil
Field Using Dynamic-INPEFA Curves of
Cyclolog Software
Based on the System Tracts and the sequence strati-
Figure 6. Comparison of δ18O and δ13C values of the Ilam car-
bonates with recent polar bulk carbonates [17], recent temper-
ate bulk carbonates [18], recent shallow water limestone [19].
graphic studies resulted from using Gamma Ray log of
well# 10 of the Hendijan oil field, the sediments of the
Sarvak Formation include two third order sediment se-
quences (Seq uences No. 1 & No. 2).
The first sequence with sequence boundary of SB2
type is placed on Kazhdumi Formation and the upper
lithostratigraphic limit of the mentioned sequence is of
SB1 sequence lithostratigraphic limit type which is
placed under upper part of Sarvak Formation and the
second sequence with sequence boundary of SB1 type
distinctive with erosional surface disconformity as a re-
sult of Orogenic phase activity is placed on middle part
of Sarvak Formation and the upper lithostratigraphic
limit of the mentioned sequence is of SB2 sequence
lithostratigraphic limit type which is placed under Ilam
Formation. Most Forwarding Surface (MFS) is observed
in the studied section of medium to thin-bedded lime-
stone with shale [20,21]. The mentioned sequences en-
compass HST and TST facies sets. Actually, based on
TST & HST facies (Sequence No. 1) the Sarvak Forma-
tion is Early to Late Cenomanian and based on TST &
HST Facies (Sequence No. 2) t his is Turonian (Figure 3).
4.1.6. Depositional Environment and Microfacies
of Sarvak Formation
As exact evaluation of reservoir rocks is possible
through of microfacies depositional environment and re-
servoir characterization analysis, by this way, well# 10 of
the Hendijan oil field with the mentioned aims was con-
sidered and evaluated. The microfacies analysis of cut-
ting samples of the Sarvak Formation in Hendijan oil
field is led to recognition seven microfacies of four fa-
cies belts (depositional environments) based on Flugel
[22] including open marine (A), bar (B), lagoon (C) and
tidal flat (D) environment. The vertical changes survey
and comparing it with modern and old depositional en-
vironments indicate that the facies of the Sarvak Forma-
tion in the studied section have been deposited in a car-
bonate ram p.
Open marin facies zone (A) consists of bioclast plagic
foram (Oligos tgin id) mudstone (A1), Plagic foram
wackestone (A2), Intraclast bioclast packstone including
Rudist and a matrix of micrite (A3). This facies zone is
characterized with pelagic forams such as Hedbergella,
Oligosteginid and to some extent Echinoid fragments
which indicates deep open marine setting [23]. High
frequency of Oligosteginid and Hedbergella suggests a
very good nutrient condition in the presence of the sparse
lime mud in matrix represent low energy environment in
this facies zone [24-28]. The specific faunal assemblage
in this facies zone can survive in normal saline open ma-
rine condition [22,29,30]. In sammrized, presence of
high amount of lime mud suggests a calm realm with no
agitation (Figures 7(A1), (2), (3)). Bar facies zone (B)

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1172
Figure 7. Depositional model of the Sarvak Formation at the Hendijan oil field; the interpretation is based on Flugel [22]. Open
marin facies zo ne: (A1) Biocla st plagic fora m (Oligostginid) mudstone, (A2) Plagic foram wackestone, (A3) Intraclast bioclast pack-
stone ; Barrier facies zone: (B) Rudist grainstone; Lagoon facies zone: (C1) Bioclast intraclast Rudist packstone, (C2) Bioclast
wackestone; Tidal flat facies zone: (D) Intraclast grainstone.
consists of Rudist grainstone. This facies zone is charec-
trerized with aboundant Rudist. Frequency of intraclasts
such as Rudist indicates a very high energy condition in
barrier setting [31-33] (Figure 7(B)). Lagoon facies zone
(C) cosists of Bioclast intraclast Rudist packstone (C1),
Bioclast wackestone (C2). This facies zone is mainly
consisted of pelagic and some benthic forams which
suggest a lagoon environment in adjacent to tidal flat
[34]. The skeletal allochems are abaoundant with high
diversity indicating a shallow bathy met with proper sa-
line condition and water circulation which provide a nu-
trient condition [35]. Low diversity of found and in-
creasing of lime mud in some facies suggests a low ener-
gy restricted lagoon [36] (Figures 7(C1) and (C2)). Tidal
flat facies zone (D) consists of intraclast grainstone. This
facies zone is generally formed from grainstone which
are associated with early fine dolomite. Presense of
dolomitos indicate internal part of a tidal flat seeting [37].
Glauconite is also abundant in this facies (Fi gure 7(D)).
4.2. Gurpi Formation
Planktonic foraminifera and calcareous nannofossils
are suitable for subdivided biostratigarphy, since they are
abundant planktonic, rapidly evolving and largely cos-
mopolitan, especially in the late Cretaceous. According
to this, the correlation between planktonic foraminifera
and nannofossils of the Gurpi formation has been studied
at the Hendijan oil field.
The lower limit of Gurpi Formation deposit is con-
formably with Ilam Formation deposit and in terms of
the upper limit, this Formation is unconformity with
Pabdeh Formation deposit. This Formation has been
formed of dark shales with thinner interbeds of marl and
limestone. Studying the thin sections of provided sam-
ples has shown dominantly biomicrite to biopelmicrite
(wackstone) and sometimes micrite (mudstone) [38-40]
OPEN A CCESS

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182 1173
all argillaceous to some extent. Small and rounded mi-
crosparitic intraclasts and spary calcite cement that fill
all foraminiferal chambers are dominant features seen in
thin sections. The sedimentary environment of this for-
mation is a bathymetrical carbonate floored basin (deep
shelf or basin margin) which has deposited its facies in
transgressive stage.
A total of 36 samples representing the oldest and
youngest strata of the 19.3m succession, were collected
up to the contact with the Pabdeh Formation. The most
detailed sampling was performed in the intervals at 1m
below and above boundaries of the Gurpi Formation.
From this set of samples 8 genera and 16 species of
planktonic foraminifera and 13 genera and 19 species of
calcareous nannofossils were determined. As a result of
this study and based on the obtained calcareous nanno-
fossils and planktonic foraminifera, the studied section is
Late Campnian to Late Maastrichtian in age, that corre-
sponding to CC23-CC25 Zones of Sissingh [10] and
Globotruncanita elevata elevata zone (33) to Globo-
truncana stuarti—Pseudotextularia varians assemblage
zone (39) of James and wind [7]. In addition, presence
index species of low latitude in Gurpi Formation have
shown that this sedimentary basin was located in low
latitude at the time of sedimentation.
4.2.1. Biostratigraphy of Gurpi Formation Using
Calcareous Nannof os sils
Calcareous nannofossils recorded in the Cretaceous
strata are believed to be appropriate means for biostrati-
graphic studies [41-44]. The importance of these cal-
careous nannofossils for correlation has been discussed
at length by [45,46]. The examination of calcareous
nannofossils of the Gurpi Formation at the Hendijan oil
field enabled us to recognize some of the standard bio-
zones defined in Mediterranean regions, especially
Tethysian domain [14,42]. In Zagros basins few studies
of Cretaceous calcareous nannofossils have been carried
out on Gurpi Formation. Calcareous nannofossils abun-
dances at the Gurpi Formation of the Hendijan oil field
were moderate. It caused that preparing only one thin
section from cuttings related to each depth had not a
good result so that some times for each depth more than
two thin sections were prepared. In the Late Campnian to
Late Maastrichtian the biozones CC23 to CC25 were
identified using the zonal scale that subdivides the upper
Cretaceous to biozones [10,41,45]. The Marker and the
most common species are illustrated in Figure 8 and are
as below:
The species Eiffellithus gorkae, Arkhangelskiella cym-
biformis, Watznaueria barnesae are the major compo-
nents and abundant of the assemblages. Quadrum sis-
singhii, Arkhangelskiella speciellata, Cribrosphaerella
ehrenbergii, Thoracosphaera operculata, Eiffelithus tur-
risefelli, Micula swastika, Zeugrabdutus embergerii are
relatively numerous. Aspidolithus parcus constrictus,
Cretarhabdus conicus, Cylindralithus nudus, Eiffellithus
eximius, Microrhabdulus attenuates, Micula decussate,
Micula murus, Placozygus fibuliformis, Watznaueria
biporta, Zeugrabdutus kerguelensis are rare (Figur e 9).
Most Cretaceous nannofossil taxa became extinct be-
low the first purple marly intercalation, a bioevent that is
synchronous with the Cretaceous/Tertiary (K/T) Bound-
ary event in low latitude areas [7,45]. The palaeoclimate
and depth of the sedimentary basin can be explained us-
ing the index species of calcareous nannofossils. The
presence of the species mentioned above in the studied
samples could indicate a very deep basin and tropical
climate conditions. From the records on abundance and
diversity of the low-latitude species, which are known to
be very useful indexes for the Late Cretaceous [7,10], it
is concluded that the sedimentary basin was located in
low latitude and tropical environment.
4.2.2. Introducing Biozonation of Gu rpi
Formation Based on Calcareous
Nannofossils
1) Biozone No. 1—Tranolithus phacelosus zone (CC23)
[10]: The first nannofossil unit recorded from the
shale of the Gurpi Formation is Zone CC23 defined
as the interval from the last occurrence (LO) of
Reinhardtites anthophrus to the LO of Tranolithus
phacelosus [14,42,45]. Because of this fact that based
on results from the samples collected from the base of
the Gurpi Formation the species such as Tranolithus
phacelosus and Reinhardtites anthophrus were not
observed, this biozone is determined using marker
events. The last occurrence (LO) of Aspidolithus
parcus divided zone CC23 to subzones one of th em is
defined as the interval from the LO of Aspidolithus
parcus parcus to the LO of Aspidolithus parcus
constrictus referred to the uppermost Campanian [10].
The age of zone is Late Early Santonian. The thick-
ness of this biozone within the Gurpi Formation at the
Hendijan oil field is 4.8 m (from depth 2944 to
2948.8 m).
2) Biozone No. 2—Reinhardtities levis zone (CC24)
[10]: Because of the species Tranolithus phacelosus
and Reinhardtites levis were not observed in the col-
lected samples, this biozone is recognized helping
merker events of LO of Aspidolithus parcus constric-
tus and first occurrence (FO) of Micula murus. Out of
this, the next nannofossil unit recording in the shale
of the Gurpi Formation defined as the interval from
the LO of Aspidolithus parcus constrictu and the FO
of Micula murus, which corresponds to the zones
CC24, assigned to the Early Maastrichtian [10,14,46].
The thickness of this biozone is 6 m (from depth 2938
to 2944 m).

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1174
(A) (B)
Figure 8. (A) Stratigraphic column and nannofissils distribution of the Gurpi Formation from the Well# 10 at the Hendijan oil field;
(B) Stratigraphic column and Planktonic foraminiferal distribution of the Gurpi Formation from the Well# 10 at the Hendijan oil
field.
3) Biozone No. 3—Arkhangelskiella cymbioformis zone
(CC25) [10]: There are several definitions attached to
the name this zone. Perch-Nielsen [45] defined it
from the LO of the species now described as
Reinhardtites levis to the FO of Micula murus or
Nephrolithus frequens. This upper boundary provides
a marker for low latitudes (M. murus) and one for
high latitudes (N. frequens). As at the Hendijan oil
field Reinhardtites levis was not observed, the last
unit recorded in the shale of the Gurpi Formation is
the zone CC25 defined as the interval from the FO of
Micula murus which is a good marker event in low
latitudes to the LO of Cretaceous coccoliths or FO of
the Sphenolithus radians and Coccolithus plagicus,
assigned to the Late Maastrichtian [10,46]. A bio-
event that is synchronous with the Cretaceous/Terti-
ary (K/T) Boundary Event in low latitude areas.
Above this extinction are two successive blooms,
Sphenolithus radians and Coccolithus plagicus.
These blooms have been recorded in many low lati-
tude areas, slightly above the K/T Boundary Event, in
the lowermost Paleocene [42,45,46]. It represents an
erosional surface disconformity as a result of Lara-
mide orogenic phase activity. The thickness of this
biozone is 8.5 m (from depth 2929.5 to 2938 m)
(Figure 8(A)).
4.2.3. Biostratigraphy of Gurpi Fm. Using
Planktonic Foraminifera
Microfossils recognized within the Gurpi Formation
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B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182 1175
Figure 9. All figures in XPL light micrographs at 1250× mag-
nification; 1. Arkhangelskiella cymbiformis; 2. Arkhangelskiella
speciellata; 3. Aspidolithus parcus constrictus; 4. Cribrosphae-
rella ehrenbergii; 5. Cretarhabdus conicus; 6. Eiffellithus exi-
miu; 7. Eiffellithus gorkae; 8. Eiffelithus turrisefelli; 9. Micror-
habdulus attenuatus; 10. Micula decussate; 11. Micula murus;
12. Micula swastika; 13. Placozygus fibuliformis; 14. Quadrum
sissinghii; 15. Watznauria barnesae; 16. Watznaueria biporta;
17. Cylindralithus nudus; 18. Zeugrabdutus kerguelensis; 19.
Zeugrabdutus embergerii; 20. Thoracosphaera operculata.
were dominantly planktonic (pelagic) foraminifera such
as Gansserina gansseri, Globigerinelloides praerihillen-
sis, Globigerinelloides ultramicra, Globotruncana bul-
loides, Globotruncana helvatica, Globotruncana lap-
parenti, Globotruncana ventricosa, Globotruncanita
elevate, Globotruncanita stuarti, Hedbergalla holmdel-
ensis, Hetrohelix navarroensis, Hetrohelix striata, Pseu-
dotextularia elegans, Rugoglobigerina macrocaphala,
Rugoglobigerina rugosa, Calcisphaerula innominata
lata (Figure 10) which show two biozones depicted in
Figur e 8(B).
4.2.4. Introducing Biozonation of Gu rpi Fm.
Based on Planktonic Foraminifers
1) Biozone No. 1—Globotruncanita elevata elevata
zone (33) [7]; associated microfossils are Globotruncana
bulloides, Globotruncana ventricosa, Globigerinelloides
ultramicra, Hedbergalla holmdelensis, Globigerinel-
loides praerihillensis, Pseudotextularia elegans. This
biozone have been seen at lower part of the Gurpi with
thickness of 5.3 m (from depth 2943 to 2948.3 m) and
the age is Late Campanian.
2) Biozone No. 2—Globotruncana stuarti-Pseudotex-
tularia varians assemblage zone (39) [7]; associated mi-
crofossils are Globotruncana lapparenti, Globotrun-
Figure 10. All figures in PPL light micrographs at 200× magni-
fication; 1. Gansserina gansseri; 2,3. Hetrohelix navarroensis;
4. Hetrohelix striata; 5,6. Hedbergalla holmdelensis; 7. Rugo-
globigerina rugosa; 8,9. Globotruncanita stuarti; 10. Globo-
truncana ventricosa; 11. Globotruncanita elevata; 12. Globo-
truncana helvatica; 13. Globotruncana lapparenti; 14,15. Glo-
botruncana bulloides; 16. Globigerinelloides ultramicra; 17.
Globigerinelloides praerihillensis; 18. Pseudotextularia ele-
gans; 19. Calcisphaerula innominata lata; 20. Globigerinel-
loides algeriana.
canita stuarti, Hetrohelix striata, Gansserina gansseri.
This biozone is observed at the upper part of the Gurpi
Formation with thickness of 13.5 m (from depth 2929.5
to 2943 m) and the age is Early to Late Maastrichtian.
4.3. Pabdeh Formation
4.3.1. Biostratigraphy of Pabdeh Fm.
Pabdeh Formation and its transition zone to Jahrum
Formation (Jahrum-Pabdeh), with a thickness of 210 m
at the Hendijan oil field overlies Gurpi Formation dis-
conformably and is overlain by the Jahrum Formation
comfortably and has an interfingering contact with it.
This Formation consists of bluish gray, thin to medium
bedded shale and marl and interbeds of argillaceous
limestones (with purple shales) at lower part, dark gray
shales and marls with intrebds of argillaceous limestone
in the middle, and alternative layers of thinly bedded
argillaceous limestone, shale and marl at the upper part
(transition zone) [4]. The dominant microfacies in Pab-
deh Formation are biomicrite. In this research, the Pab-
deh Formation and its transition zone to the Jahrum
Formation were studied. In this regards, 110 microscopic
slides from these Formations were collected. Out of this,
18 genera and 42 species were determined and their
ange chart was plotted (Figure 11). The distribution of r

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1176
Figure 11. Stratigraphic column, Planktonic foraminiferal distribution and sequence stratigraphy of the Pabdeh and its transi-
tion zone (Jhrum-Pabdeh) from the Well# 10 at the Hendijan oil field.
OPEN A CCESS

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182 1177
foraminifera species indicates that there are 4 biozones at
the Hendijan oil field. On this basis, the age of sediment-
tation of Pabdeh Formation can be suggested to be from
late Paleocene (Thanetian) to lower Eocene and its Tran-
sition zone can be suggested to be from Lower Eocene to
Late Eocene. Microscopic studies and lithological varia-
tions of these Formations offer a basin margin environ-
ment for Pabdeh Formation and fore slope to basin mar-
gin environment for its transition zone. Index species
recognizing at this Formation are as below:
Acarinina bullbrooki, Catapsydrax dissimilis, Globi-
gerina ampliapertura, Globigerina praebullo ides, Globi-
gerina triloculinoides, Globigerina velascoensis, Globi-
gerina yeguaensis, Globigerina senni, Globigerinatheka
Mexicana, Globigerina sp., Globorotalia abandoca-
merata, Globorotalia crassata, Globorotalia cocoaensis,
Globorotalia renzi, Globorotalia rex, Globorotalia sp.,
Guembelina sp., Hantkenina alabamennsis, Morozovella
acuta, Morozovella aequa, Morozovella angula ta, Moro-
zovella aragonensis, Morozovella formosa formosa,
Morozovella gracilis, Morozovella lehneri, Morozovella
spinulosa, Morozovella pseudobulloides, Morozovella
velascoensis, Morozovella sp., Miliola, Orbulina uni-
versa, Orbulina sp., Planorotalites pseudomenardii,
Praeorbulina transitoria, Pyrgo, Robulus sp., Spirolina
sp., Turborotalia centralis, Turborotalia cerro-azulensis,
Truncorotaloides topilensis, Truncorotaloides rohri,
Zeauvigerina sp. (Figures 12 and 13).
4.3.2. Introducing Biozonation of Pabdeh Fm.
and It s Transi tion Zone (Jahrum Fm.)
1) Biozone No. 1—Morozovella velascoensis-plano-
rotalites pseudomenardii assemblage zone (42) [7]: This
biozone includes the all sediments of Late Paleocene in
the studied stratigraphic section. The thickness of this
biozone is 35.5 m and its index microfossils include:
Morozovella velascoen sis, planorotalites pseudomenardii,
Globorotalia elongata, Morozovella Formosa, Morozo-
vella gracilis, Morozovella aequa.
2) Biozone No. 2—Globorotalia rex, Morozovella
Formosa, Morozovella aragoensis assemblage zone (45)
[7]: The thickness of this biozone is 62 m and its micro-
fossils include: Globorotalia rex, Morozovella Formosa,
Morozovella aragoensi which indicate the age of Early
Eocene.
3) Biozone No. 3—Truncorotaloides-Porticulasphae-
ra Morozovella spinulosa assemblage zone (47) [7]: This
biozone includes the all sediments of Middle Eocene in
the studied stratigraphic section. The thickness of this
biozone is 52 m and its microfossils include: Truncoro-
taloides spp., Porticulasphaera spp., Morozovella spinu-
losa, Morozovella lehneri, Morozovella aragoensis,
Globorotalia centralis, Hantkenina sp., Catapsydrax sp.
4) Biozone No. 4—Turborotalia cerro-azulen sis-Hant-
Figure 12. All figures in PPL light micrographs at 200×
magnification; 1. Globigerina ampliapertura; 2. Globigerina
praebulloides; 3. Globigerina triloculinoides; 4. Globigerina
velascoensis; 5. Globigerina yeguaensis; 6. Globigerina
senni; 7. Globigerinatheka Mexicana; 8. Globigerina sp.; 9.
Globigerina praebulloides; 10. Guembelina sp.; 11. Zeau-
vigerina sp.; 12. Turborotalia cerro-azulensis; 13. Truncoro-
taloides topilensis; 14. Truncorotaloides rohri; 15. Turboro-
talia centralis; 16. Morozovella acuta; 17. Morozovella
aequa; 18. Morozovella angulata; 19. Morozovella arago-
nensis; 20. Morozovella formosa formosa.
Figure 13. All figures in PPL light micrographs at 200×
magnification; 1. Morozovella gracilis; 2. Morozovella
lehneri; 3. Morozovella spinulosa; 4. Morozovella velas-
coensis; 5. Globorotalia abandocamerata; 6. Globoro-
talia crassata; 7. Globorotalia cocoaensis; 8. Globoro-
talia renzi; 9. Globorotalia rex; 10. Praeorbulina transi-
toria; 11. Planorotalites pseudomenardii; 12. Catapsy-
drax dissimilis; 13. Robulus sp.; 14. Miliola; 15. Spirolina
sp.; 16. Pyrgo williamsoni; 17. Acarinina bullbrooki; 18,
19. Hantkenina alabamenns is ; 20. Orbulina sp.

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1178
kenina assemblage zone (52) [7]: This biozone includes
the all sediments of Late Eocene in the studied strati-
graphic section. The thickness of this biozone is 72 m
and its associated microfossils are: Turborotalia cerro,
Hantkenina sp., Globorotalia centralis, Catapsydrax sp.,
Globigerinatheka sp.
4.3.3. Gurpi and Pabdeh Formations Boundary
At the Hendijan oil field the boundary between Gurpi
and Pabdeh Formations is of disconformity type. Con-
sidering lithological similarity of both Formations, de-
termining of this unconformity from field observations is
not possible and it is done by means of microscopic
studies and microfossil recognition. The boundary be-
tween the two Formations, at the Hendijan oil field, rests
at the base of purple shale. In this region, the recognition
of Globorotalia (Morozovella) velascoensis, which is
attributed to lower part of the Pabdeh Formation, sepa-
rates the two formations. This bed represents a non-de-
positional (epirogeny) period from the Late Maas-
trichtian to the end of Early Paleocene (Figure 14).
Figure 14. Microfacies criteria observed in microscopic ex-
amination of Gurpi and Pabdeh Formations accompanying with
planktonic microfossils and the purple Shale as a factor of Un-
conformity.
4.3.4. Sequence S tra tigraphic Description of the
Pabdeh and Jahrum-Pabdeh Fms. in Well
#10 of the Hendijan Oilfield Using
Dynamic-INPEFA Curves of Cyclolog
Software
The study of vertical variations in th e facies of Pabdeh
Formation and its teansition zone has mainly shown one
sedimentary sequence (the third class cycle) including 5
subsequences. The lower boundary of Pabdeh Formation
is identified by purple shale from Gurp i for mation (S B2).
In the relative static state of sea level HST facies with the
thickness of 49 m includes alternation of pelagic facies
and redeposited limestones. TST facies with the thick-
ness of 174 m includes mudstone as well as Globrotalia,
Globigerina bioclast wackstone. Maximum flooding
surface (MFS) of the sea is characterized by thin bedded
dark shale facies. The main result can be inferred of dif-
ferent subsequences in Pabdeh Formation is that there
were fluctuations with sea level. The existence of ben-
thonic bioclast as well as the mixture of benthonic envi-
ronment and platform facies indicates the high rate of
deposition which causes tempestite deposits, carbonate
slumping from platform margin with steep slope and its
deposition in the sea depth [47].
4.3.5. Depositional Environment and Microfacies
of Pabdeh and Jahrum-Pabdeh Fms.
The interpretation of depositional processes and sedi-
mentary paleoenvironment of the Pabdeh Formation is
done by lithofacies and biofacies and, in particular, its
microfacies. The following microfacies criteria which are
observed in microscopic examination of the Pabdeh
Formation have shown a deep marine environment [31,
48-51] and a platform environment for its transition zone.
Microscopic samples determined that the identified fa-
cies of the Pabdeh Formation have been all deposited in
the sea depth. They can be divided into two groups: pe-
lagic (Group A) and calciturbidite (Group B) facies. Cal-
citurbidites can be seen as interbedded in pelagic facies
especially within transition zone.
1) Pelagic Microfacies
A1—Mudstone/Shale
Approximately this facies totally includes lime mud in
black shale. Black shale facies in the sequence of the
Pabdeh Formation has relatively great expansion. It is
mainly seen in alternation with globigerina bioclast
mudstone and globrotalia. Bioturbation is another feature
of this facies. Mudstone/shale facies has been seen with
thinbedded lime shale facies (Figure 15(A)).
A2—Globrotalia, Globigerina Bioclast Mudstone
In this facies less than 5% of skeletal allochem from
Globigerina and Globrotalia family exists in a micritic
matrix. This facies has been deposited in a low order
environment of open sea and its lithostratigraphic con-

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182 1179
Figure 15. Microfacies of the Pabdeh Formation at the Hen-
dijan oil field; A: mudstone/gray shale (A1 facies); B) Globro-
talia-Globegerina bioclast mudstone (A2 facies); C) Globro-
talia-Globegerina bioclast wackestone (A3 facies); D) Glouco-
nitic Globegerina bioclast packstone (A4 facies); (E)-(G) bio-
clast wackestone (B1 facies); (H) Intraclastic peloiedal bioclast
wackestone (B2 facies).
stitutes includes thin to medium-bedded dark lime shale
(Figure 15(B)).
A3—Globro talia, Globigerina Bioclast Wackstone
About 40% of this facies is Globrotalia, Globigerina
bioclast. The matrix of this facies is gray micrite and also
a low percent (less than 5%) of pellet is found. In this
facies a low percent of glauconitization in foraminifera’s
pores has been seen (Figur e 15(C)).
A4—Glauconit Globigerina Bioclast Packstone
Over 55% of the sample mass of this facies consists of
the species such as globigerina and globrotalia in a mic-
ritic matrix. The mentioned facies includes 10% - 15%
glauconitization in the pores of plankton microfossils
(Figure 15(D)).
The existence of planktonic bioclasts related to deep
sea such as Globigerina, Globrotalia and abundant mic-
rite indicates the deposition of this group in deep sea
environment [22].
2) Calciturbidite Facies
B1—Bioclast Wackstone
In this facies bioclasts from Nummulite and Milliolide
have been seen in a micritic matrix. In some similar
samples, 20% to 35% of the facies has been dolomitized.
There are also 25% to 40% of planktonic microfossils in
the sample such as Globigerina and Globrotalia. This
facies has been deposited in the form of calciturbidite in
the sea depth and interbedded in pelagic limes and sh ales.
It is important to be mentioned that the lower boundary
of calciturbidite with shales is abrupt (Figures 15(E) and
(F)).
B2—Intraclastic Peloidal Bioclast Wackstone
In this facies about 30% of pellet, 15% of intraclasts
and 25% of skeletal allochem from milliulide family
with debris of planktonic shell in a micritic matrix have
been seen (Figure 15(H)).
Existence of benthonic bioclasts such as Milliolide and
Nummulite in calciturbidite facies (B1 and B2) indicates
deposition in a platform environment. The indication that
pelagic and turbidite facies are interbedded and the mix-
ture of planktonic and benthonic grains in calciturbidites
shows the high rate of deposition (Figure 16).
5. CONCLUSION
In this study, the Early Cenomanian-Late Eocene de-
posits of the Sarvak, Ilam, Gurpi, Pabdeh and Jahrum-
Pabdeh Formations at the Hendijan oil field were studied
in detail with regard to microbiostratigraphy, microfacies,
stratigraphy, and geochemistry. Our data provide insights
into the palaeoenvironmental evolution and sea-level
fluctuations using D-INPEFA curves. Planktonic fo-
raminifera and calcareous nannofossils which are suit-
able for subdivided biostratigarphy, since they are abun-
dantly planktonic, rapidly evolving and largely cosmo-
politan, were used for biozonation leading to accurate
time scale of each formation. Sarvak and Ilam Forma-
tions have been formed of marly limestone with thinner
interbeds of marl and limestone. Because of the similar
litology of these Formations, recognition of boundary
between Ilam and Sarvak Formations was done using
geochemical analysis (oxygen and carbon isotopes). 18
genera and 26 species and 10 genera and 6 species of
planktonic foraminifera were determined in Sarvak and
Ilam Formations respectively. Based on the obtained
foraminifera, Sarvak Formation is Early Cenomanian to
Turonian and Ilam Formation is Campnian in age. Based
on detailed sedimentological analysis over the Sarvak
Formation, four facies associations including tidal flat,
Figure 16. Sedimentary environment model of the Pabdeh
formation A: pelagic facies B: calciturbidite facies.

B. Soleimani et al. / Natural Science 5 (2013 ) 1165-1182
1180
barrier, lagoon and open marine have been recognized.
The detailed microfacies analysis and sedimentological
criteria suggest that the Sarvak was deposited in a car-
bonate ramp. Sequence stratigraphy was evaluated based
on INPEFA curves resulting from Gamma ray logs. Out
of this, two-third-order sequences in the study section
were identified for Sarvak Formation. Gurpi Formation
has been formed of dark shales with thinner interbeds of
marl. As a result of the correlation between 8 genera and
16 species of planktonic foraminifera and 13 genera and
19 species of calcareous nannofossils determined in this
Formation, the Gurpi Formation is Late Campnian to
Late Maastrichtian in age. In addition, peresence index
species of low latitude in Gurpi Formation shows that
this sedimentary basin was located in low latitude at the
time of sedimentation. Pabdeh and Jahrum-Pabdeh For-
mations have been formed of shale and marl with inter-
beds of argillaceous limestones and shaly limestone re-
spectively. 18 genera and 42 species of planktonic fo-
raminifera were determined in these Formations. Based
on the obtained foraminifera, Pabdeh Formation is
Thanetian and Jahrum-pabdeh Formation is Early to Late
Eocene in age. Microfacies study indicated 6 pelagic and
calciturbidite microfacies deposited in deep marine. Cal-
citurbidite facies were formed during sea level h igh stand,
when high rate of carbonate production resulted in
transportation of carbonate sediment in deep sea. Se-
quence stratigraphy study shows that Pabdeh and Jah-
rum-Pabdeh Formations consist of one main depositional
sequence.
6. ACKNOWLEDGEMENTS
The authors express their thanks to Shahid Chamran University au-
thorities. We are indebted to Mr. M. H. Hosseini Farzad, chairman of
the Geology Department of the National Iranian Offshore Oil Company
(NIOOC), for assistance in our fieldwork and sampling. We are also
indebted to Mr. A. Mansour and Dr. H. Pourkaseb (University of Sha-
hid Chamran) for their fruitful discussions and encouragements. We
thank two anonymous reviewers for their constructive comments that
helped used improve this paper.
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