First record of bedded limestone inside Upper BakhtiariFormation, Sulaimani Governorate, Kurdistan Region, NE-Iraq

IOSR Journal of Applied Geology and Geophysics (IOSR-JAGG)

e-ISSN: 2321–0990, p-ISSN: 2321–0982.Volume 3, Issue 5 Ver. I (Sep. - Oct. 2015), PP 01-08

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DOI: 10.9790/0990-03510108 www.iosrjournals.org 1 | Page

First record of bedded limestone inside Upper BakhtiariFormation,

Sulaimani Governorate, Kurdistan Region, NE-Iraq

Kamal Haji Karim1, AmanjIbrahim Fattah

2 and Fouad MohammedQader

3

1,2.3(Department of geology, School of Science/ University of Sulaimanie,Kurdistan Region, Iraq )

Abstract: Thick beds of detrital and stromatoliticlimestones are found for the firsttime inside Upper Bakhtiari

Formation in two different localities in the Sulaimani Governorate, NE-Iraq. The first locality is Dokan area at the

northwestern limb of Kosrat anticline while the second one is located in the Garmianarea betweenChamchamaland

QadirKaram towns.The limestones change laterally and vertically to conglomerate of the latter formation.The beds

are located on or inside the conglomerateof latter formation and only in one place it changes laterally to green marl.

Petrographically the limestones consistof alternation of limestone layers of intraclastic, oolitic and pisoidal

andoncoidallithology.The lithology indicates relatively sudden environment changes and unstable energy regime

which most possibly indicated deposition in freshwater lakes. The lakes are formed due fluvial activities such as river

cutoff (oxbow lake)and river damming by rock slides or river plugging. The paleogeography of the Upper Miocene

and Pliocene had assistedthe deposition of the limestone in the lakes due to compartment of source areas. In many

areas, the source area was consisted of limestone terrains during latter two ages and from these terrains the

carbonate rich solution and clasticsare supplied to the rivers and the lakes in which carbonates had deposited.

Keywords: Bai Hassan Formation, freshwater limestone, limestone beds,Upper Bakhtiari Formation, stromatolitic

limestone

I. Introduction The Upper Bakhtiari is well known for its polymictic conglomerate in Iran and Iraq and Turkey which

consist of mixture of gravels and boulders of cherts, limestones and Igneousclasts. While the record of occurrence of

bedded limestone in the Upper Bakhtiari Formation is the first one in the present study. But it does mean that it has

not some indirect background in the literatures as Karim and Taha (2012)[1] has studied in detail a succession of

limestone conglomerate that belong to Upper Bakhtiari (Bai Hassan) Formation.they cited that the succession is

about 300m thick and located around Dokan dam; therefore they call it Dokan Conglomerate. They attributed the

deposition of limestone conglomerate to nature of the source area which was consisted of exposure of limestone such

as Qamchuqa Formation. In Iran, Sahraeyan (2013)[2] has recorded clast-supported limestone conglomerate under

Bakhtiari Formation. He assigned it as a non-marine depositional system of braided rivers.

According to Jassim and Goff (2006)[3], the Bakhtiari Formation (including Upper and Lower Bakhtiary)

was first described from Iran by Busk and Mayo in 1918 and the formation was recognized by Bellen et al. (1959)[4]

with using same term in Iraq too. In Iraq the name of the Lower and Upper Bakhtiari formations are changed to

Mukdadiya and Bai Hassan formations respectively by Al-Rawiet al. (1993)[5].Buday (1980)[6] cited that the

formation in is largely made up of coarse and thick fluviatile and estuarine conglomerates, products of erosion of the

rising mountain ranges, deposited in one or more sinking troughs in front of those ranges. They added that in the

folded zones residual and terrace gravels of Recent and Pleistocene age rest with high angular discordance on deeply

eroded Upper Bakhtiari and older formations.The formation is composed almost purely of terrigenousclastics from

silt size to boulder conglomerates. In general, the grain size of the clastics increases upward. The prevalence of the

conglomerates in the upper part of the formation had been the main' reason for considering that part as an

independent formation (Bellenet al.1959)[4].

The Upper Miocene- Pliocene conglomerate consists of very thick pile of pebbles, pebbly sandstone and

interbedded with red claystone and erosional surfaces. This pile includes Mukdadyia and Bai Hassan (Lower and

Upper Bakhtiari) Formations.The thickness of the latter Formation(mainlyasconglomerate) is more than 1500m and

is located mainly in the Low folded Zones. The paleocurrent of this conglomerate is towards southwest (Karim et al.,

2009)[7]. In addition to conglomerate, Bai Hassan Formation containsthick beds ofclaystone and sandstone in fining

upwards cycles. The lower contact with Mukdadiyah Formation isconformable and marked at the base of the first

conglomerate bed (Al-Musawi, 2008)[8].

II. Locationand Geomorphology During fieldwork, on the outcrops of the Upper Bakhtiari Formation,limestone beds arefound in two

different areas inside the formation. The first locality is located about 10 kms to the northwest of Dokan Town at 500

m to the southeast of Mewzha villageon the northeastern side ofKosratMountain(or anticline) inside the High Folded

Zone (Fig.1, 2 and 3).The latitude and longitude of thelocation are 36o06

-28.52

= N 44

o48

-04.46

= E .Thislocation is

First record of bedded limestone inside Upper BakhtiariFormation, Sulaimani Governorate, Kurdistan…


looking (from the south) over the Dokan lake and Marga plain.These beds are referred to in the ext as “northern

limestone”

The second one is located between the three villages of Hanara(atsouthwest), Mordana (at the west) and Hama Sherif

(at northeast). These villages are located at 18 and 3kms to the south of and northwest of Chamchamal

andTakyiayJabary townsin the side Low Folded Zone (Fig.4and 5). At this location, two outcrops are found which

are separated by 700mand the latitude and longitude of the outcrops are 35o22

-38.3

= N 44

o45

-47.5

= E.and 35

o22

-0.3

=

N 44o46

-19.5

= E. These beds (two outcrops) are referred to in the text as “southernlimestone”.

III. MaterialsandMethod of The Study The study depends both on the field work and microscopic study of the samples by which the lithology and

fossils of the samples are studied. Fifteen thin sections are prepared for petrographic study and three samples are

prepared and sent to England for nannofossils analysis by Nannofossils Consultancy Ltd, London. The location of

the limestone beds are plotted on topographic maps which later changed to geological map. The previous studies

reviewed and used to find the previous study about Bakhtiari Formation. The main material of this study is beds of

limestone that are apparently associated with the conglomerate of Upper Bakhtiari Formation.

Fig.(1)Tectonic map of the Northern Iraq (Jassim and Goff, 2006)[3] on which the location of the limestone

outcrops are shown

Fig. 2: Geological map of the studied area (modified from Karim and Taha, 2012)[1]



Fig.(3)Bedded (freshwater) limestone inside Dokan Conglomerate south and southeast of Mewzha village.

Fig.(4)Topographic map of the area between Chamchamal and QadirKaram towns shows the location of the two

outcrop of limestone inside Upper Bakhtiari Formation

Fig.(5)Outcrop of the limestone bed of the southern limestone near TakyaiJabari town. The gradation

of the limestone to conglomerate can be seen in the photo C.



IV. Petrography of The Limestone Both the northern and southern limestones are nearly similar in lithology as they consist of massive or well

bedded milky to grey limestones and they are hard and coherent. In both locality, they laterally and vertically change

to conglomerate and the transitional zone consist of pebbly limestone. In one locality, the southern limestone changes

to green marl from which samples are taken for age determination by nannofossils.

4-1-Detrital limestone

In the published work of Karim and Taha (2012)[1] a 300m of limestone conglomerate succession (Dokan

conglomerate) is found in the same area of the northern limestone. The latter two authors proved that Dokan

conglomerate is proximal sediment of Upper Bakhtiari Formation. This succession can be considered as the detrital

limestone of very coarse grain (in the size of gravels). Since the northern limestone of the present study is associated

with the Dokan conglomerate, therefore the detrital limestone of sand size is not strange to the studied area as both

derived from limestone terrain source area.

The detrital limestone beds are clearer in the northern limestone than the southern one and they consist of

crudely laminated beds about 30-100 cm thick.Under the 10X hand lens the detrital grain can be seen as white and

rounded grains more or less similar to cluster of rice grains.Perographically, they consist, under polarized

microscope,of fine grain of dark colorwhich are sorted and rounded with the sand size. The grains havemore or less

diffused boundaries and milkycolorandcalciticmatrix (Fig.6). The beds of the detrital limestone change laterally and

vertically to limestone conglomerate. No dolomite lithoclasts and fossilbioclasts are observed among the grain. This

may due to weakness (against reworking) of these two grain types while the pure limestone grains are most resistive

to breakdown especially in the fresh water. The detrital limestone contains of petrified plant roots fragments and

calcified plant debris. The fragment are dark brown in color and has the thickness of 5- 20 mm, the fibers and cortex

cell of the petrified root remains can be seen on the surface (Fig.7). The debris exists as elongate and randomly

arranged fragments which appear as scratches of knife on rocks (Fig.7).

Fig.(6)A) elongate superficial ooids and B) detrital limestone grains in the northern limestone.

Fig.(7)A) plant debris that preserved the fibers and cortical cells of root. B) The limestone contains plant debris that

is replaced (by calcite) elongate plant debris, vugs and fenestrae. Both samplesare fromMewzha village

4-2-Stromatolitic limestone

Stromatoliticlimestone is nearly similar to detrital limestone in color and laminations but the lamination are

more crumpled and with lighter and darker color tones between the alternating lamina.Under polarized microscope

the limestone appear as alternation of dark and light color fine grain limestones which are crinkled and may be

associated with detrital limestone. These grains, as a lamina alternate with stromatolitic limestone lamina. Both types



of limestones have the milky colorand have characteristics of lacustrine limestone that are given by Freytetand

Verrecchia(2002)[9] whom stated that they are varved, laminated, homogeneous, peloidal, brecciated, gravelly,

bioturbated (burrows), bioclastic, algal, and stromatolitic.They added that detrital beds are sometimes present and are

interpreted as bottomset deposits.

The stromatolitic limestone (Fig.9 B) containsfenestraltexturewhich determined by Flugel (2010)[10], that is

results from grain bridging and gas bubble Formation associated with decomposition or organic material. After that,

the open spaces of the fenestral fabrics are filled with sparite. Friedman (1995) observed same texture (or facies) in

the upper parts of tidal flatsof Arabian Gulf.

The Evidencethat UpperBakhtiari Conglomerate contain of fresh water limestone is the content of petrified

plant roots from which the fibers and cortex sell can be seen on the surface of petrified root remain (Fig. 7). These

limestones are deposited in the lakes that were formed due to streams channel abandonment or due to growth of

anticlines in front of streams or in front of alluvial fan.

4-3-Oolitic limestone

Ooids are one of the constituents of recent and ancient carbonate successions in the studied area since

Khanaqa et al (2013)[11],Ameen(2008)[12] and Karim et al. (2009)[7] found ooids in the recent, Cretaceous and

Jurassic rocks respectively. According to Davies et al., (1978),three conditions are usually considered necessary for

ooids formation which are (1) water supersaturated with aragonite or high-Mg calcite, (2) availability of a of nuclei,

and (3) presence of the above two condition in an agitation milieu.Pacton et al (2012)[13] discussed the role of the

microbs in formation of ooids.

In the southern and northern limestones, coatinggrains are abundant in the form of pisolite and irregular

oncoids. But well developed ooids are not found which notifies important signature which will be discussed in the

other sections. The observed ooids are radial ones which are consisting of the radial needles and have fibrous form.

The needles are needles are usually truncated by the next layer and arranged as concentric dark and pale grey laminae

within the cortex (Fig.8A).When the grain has only one dark micritic thin layer it called cortoid.According to

Flugel(2004)[10] the radial ooids are formed in quiet water of marine and nonmarineenvironment

4-4-Oncoid andpisoid Oncoidsare generally similar to tangential ooids which havesize oflarger than 2mm in diameter. Ameen

(2008)[12], Daod and Karim (2010)[14] and Karim et al (2011)[15]hadfound oncoids in Cretaceous, Jurassic and in

recent sediments in the studied area.According to Boggs (2009)[16],pisoids are coated grains that resemble ooids but

they differ in theirinternal structures and they are generally less uniform in shape and larger (several millimeter to

centimeters). Most of them are non-marine in origin.

The thin sections study shows that both southern and northern limestonescontain large (more than 2mm in

diameter) irregular coatedgrainsthat satisfythe above characteristics of both oncoids and pisoids but they are more

close to the latter one (Fig.9). Under polarized microscope both limestone are similar to calcreteas they show signs

of both leaching, deposition and encrustation. In rare case the dripstones can be seen

Fig.(8A)Radial ooids and, B) with internal sedimentation (dark areas) limestone in the northern limestone, S6,

20X.



Fig.(9)Highly amalgamated limestone with irregularpisoid in the southern limestone inQadirKaram area. B)

Stromatoliticlimestone withbirds eye

V. Origin of The Limestone Bed The record of the limestonebeds inside the Upper Bakhtiari Formation is extraordinary event since this

formation is known for its prevalence of conglomerate and other clastics. However, Karim and Taha (2012)[1] found

300 meters of limestone conglomerate in Dokan area and they proved that it belongs to Upper Bakhtiari Formation.

The proving was based correlationof the limestone conglomerate withits equivalent inside proper Upper Bakhtiari

Formation near Taqtaq town. In Iran,Sahraeyan et al. (2013) [2] havefound limestone in the southwest Iran inUpper

Fars (Aghajari) Formation which is equivalent to Lower Bakhtiari Formation of Iraq. They cited that the limestone

exists in a section which is about 2221 m thick and consisted of sandstone, claystone and conglomerate.

The deposition of limestone beds in side Upper BakhtiariFormation is due to the fact that in many places

the source area was compartmentalized during Upper Eocene – Pliocene to different drainage basins with different

rocks outcrops. Some basins were consisted oflimestone source area while others were consisted of mixed rocks

(sedimentary and ophiolite) source area. According to Karim and Taha(2012)[1], from the limestone outcrops

limestone conglomerates were deposited in the proximal areas (High and Imbricated Zones) while the cherts and

ophioliteswere derived from the Thrust Zone and deposited as mixedsediments in the distal areas. The sediment area

transported from source areas to the side of deposition by river.

It was possible that these rivers are suffered from one of two processes, the first is natural damming by mass

wasting (large slides and debris flows) the second is oxbowcutoff of meandering river. The developed fresh water

lake was site of deposition of detrital and stromatolitic limestone on the previous coarse clastics. The lateral gradation

to pebbly limestone and then to ortho- conglomerate is the evidence to its deposition in fluviatile environment

(Fig.5C). In theslides, desiccation cracks (Fig.11 left), bioturbated and highly amalgamation limestone (Fig.12), can

be seen which denote deposition in variable flow regime and terrestrial environments.

The accurate age determination of the limestone inside Upper Bakhtiari Formation is difficult. As

mentioned before, marlstone occurs with the southern limestone from which three samples are taken and send to

England for age determination. Only one sample was contained index fossils and it gave the age of Middle Miocene

to LateMiocene (Fig.10).

Fig.(10)The nannofossils in the green marl that is associated with limestone beds in the southern area (near

TayiJabariVillage)



Fig.(11) Left) cracks in detrital limestone which may be formed by desiccation, Right) vugyand pisoidal limestone

of southern limestone

Fig.(12) A)Vugs and bioturbationclasts (dark pieces near the finger) in malgamated limestone beds in the southern

limestone. B) Iron rich laminae

VI. Conclusion

1-The limestone beds are found in two different localities inside Upper Bakhtiari for the first times.

2-The limestone bed are consist of massive to crudely laminated layers that are composed of detrital or stromatolitic

or oolitic beds.

3-They derived from limestone source areas during Upper Miocene and Pliocene

4-They are deposited in fresh water (Fluviatile) environment of unstable and high energy condition.

5- The paleogeography of the Upper Miocene–Pliocene was of different contrast topography of high mountain, low

land with dominate of fluvial and fresh water lakes deposits.

References [1] K.H Karim, and Z. A Taha,.. Origin of limestone conglomerate in Dokan Area, Kurdistan Region, Northeast Iraq, Iraqi Bulletin of

Geology and mining, 2(3), 2012, 15-24.

[2] M Sahraeyan,.. Sedimentology and palaeogeography of conglomerates from the Aghajari Formation in Zagros Basin, SW Iran, International Journal of Advanced Geosciences, 1(1)2013, 13-22.

[3] S.Z Jassim,.andJ. C.Goff, ,. Geology of Iraq. Dolin, Prague and Moravian Museun, Berno. 2006, 341p.

[4] R. C. Bellen, H. V., Dunnington, R. Wetzel, and D.Morton,.LexiqueStratigraphique, Interntional. Asie, Iraq, Fasc, 10a, Paris,10a,1959, 333 p.

[5] YT Al-Rawi, AS Sayyab, JA Jassim, M,Tamar-Agha,AIAl-Sammarai, SA Karim, MABasi, DHagopian,KM Hassan, M Al-Mubarak, A

Al-Badri, SH Dhiab, FM Faris, F Anwar New names for some of the Middle Miocene–Pliocene formations of Iraq (Fatha, Injana, Mukdadiya and Bai Hassan formations). Iraqi Geol J 25 (2), 1993, 1–18.

[6] T Buday, The Regional Geology of Iraq. Vol.1: Stratigraphyand Paleogeography. Publications of GEOSURV, Baghdad, 1980.445p.

[7] K.H. Karim, A.I Fatagh, A.Ibrahim,H.Koyi, Historical development of the present day Lineaments of The western Zagros Fold-Thrust belt: a case study from Northeastern Iraq, Kurdistan Region, Iraqi journal of Earth Sciences, 9(1), 2009, 55-70.

[8] H. A. Al-Musawi, .Geology and structure of WadiShalghaharea,East Erbil, North Iraq, Iraqi Bulletin of Geology and Mining,4(1), 2008,

49-57.



[9] P.Freytet and E. P.Verrecchia,. Lacustrine and palustrine carbonate petrography: an overview. Paleolimnology 27, 2002,: 221-237.

[10] EFlügel, Microfacies of Carbonate Rocks: Analysis, Interpretation and Application, 2010, 590p. Springer Verlag, Derlin

[11] P.A., Khanaqa, K.H. Karim, and V.Thiel, Characeae-derived carbonate deposits in Lake Ganau, Kurdistan Region, Iraq, Facies ,( Springer Verlage) 59(4), 2013,653-662.

[12] B.M.Ameen, Lithostratigraphy and Sedimentology of Qamchuqa Formation from Kurdistan Region, NE−Iraq.Unpublished Ph D. Thesis.

University of Sulaimani, 2008, .147p. [13] M. Pacton, D.Ariztegui.,D.Wacey, M. R Kilburn,C.Rollion-Bard, R.Farah, and C.Vasconcelos,. 2012. Going nano: A new step toward

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[email protected](6) 547–550. [14] H. S. Daoud, and K. H. Karim, Types of stromatolites in the Barsarin Formation(Early Jurassic), Barzinja area, NE-Iraq Iraqi Bulletin Of

Geology And Mining,6(1), 2010, 47-57.

[15] K. H.Karim,P. A.Khanaqa, andB. M Ameen, Types of recent microbialite in slightly acidic spring in Ranyia area, Kurdistan, NE Iraq, Iraqi Bulletin of Geology and Mining, 7(2), 2011, 27- 40.

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First record of bedded limestone inside Upper BakhtiariFormation, Sulaimani Governorate, Kurdistan Region, NE-Iraq