Investigating the Stratigraphy and the Gender of Nano-Fossils in the Lower Part of the Abtalkh Formation in Kopet Dagh Zone

A structural-sediment zone of Kopet Dagh is one of the geological units. The southern Kopet Dagh zone is limited to Binalood and the northern limit is with the Turan plateau fault and is created as sediment (Trough) in the late Triassic. The main fault zones are divided into two groups of foundation faults and overthrust. Kopet Dagh is a giant gas field between Turkmenistan, Iran and Afghanistan. Most areas of the region have a temperate climate so cold. From the middle Cambrian to the present, five phases of orogeny have occurred in the region. The geographic location of the study area is 37 ̊43'03"N latitude and 55 ̊35'47"E. In terms of stratigraphic formations in the Cretaceous period, Kopet Dagh area, respectively, is from old to new, including: Shurijeh, Zard, Tiregan, Sar Cheshmeh, Sanganeh, Aitamir, Abderaz, Abtalkh, Neyzar and Kalat. Abtalkh formation is one of the most important rock units in the late Cretaceous in the Kopet Dagh Basin. Abtalkh formation is 489 m and its stratigraphic units are 80 meters of dark grayshale, 20 km dark grayshale with calcareous layers with Inoseramus, 50 m gray marl tend to bluish with Siliceous limestone interlayers, 19 meters of gray-blueshale, 320 meters of light gray shale withthinlayer limestone interlayers. To take pictures of the samples, 100× objective lens and digital camera were used. In the course of this study, the lower part of Abtalkh formation was in Itamir cutting of the study and 9 genera were identified. Recognized calcareous Nannofossil had diversity and abundance. In general, in the greater thickness of the study, samples have moderate preservation. In some cases, the impact of dissolution phenomenon was so great that the main part of the species were corroded. Paying attention to the range of the rise and fall of index species and fossil assemblages, 4 biozones were identified for cutting according to the zones (CC18-CC21) of Sysyngzoning, 1977.


Introduction
Sedimentary-structural Kopet Dagh is one of the geological units.South limit of Kopet Dagh is limited to Binalood and the northern limit is the plateau Turan fault.Kopet Dagh is a mountainous region that has become the current landscape, because of the latest phase of Alpine folding and erosion of its outcome.The Kopet Dagh zone becomes sediment basin after the early Cimmerian orogeny, meaning when apparently a collision between Iran and Turan was ended [1].The basin is created by the closure of the Paleo-Tethys Ocean and during the Middle to Late Triassic orogenic and probably in the Middle Jurassic.It is composed of two thick carbonate and debris sediments that were deposited from the Jurassic to the Neogene.Kopet Dagh is a large gas field among the three countries of Iran, Afghanistan and Turkmenistan and huge gas fields of Khangiran in Iran, Dolat Abad-Donmez, Sharlik, Gazelle, Bayran Ali and Mehri in Turkmenistan and Sulfur in Afghanistan have been discovered in the basin.Basin area is about 5500 square kilometers and is approximately 3.3% of the total area of Iran (Figure 1).Two parallel mountain ranges cover the in some areas is over eight thousand meters.Precipitation of tectonic events, governing the Kopet Dagh zone is similar to the Zagros zone, such that it can be referred to final folding, public process of folds, lack of magmatic endeavors, and the same regimen for compression and so on.Kopet Dagh region's weather is influenced by several factors.
One of these factors can be the change in the country districts that changes at a height  [3] has drawn the Geological map of Kopet Dagh.[4] has studied geological exploration of gas fields in Sarakhs and Khangiran.[5] has studied foraminifera in sediment sequence of Kopet Dagh of the Middle Jurassic to Upper Cretaceous.[6] [7] [8] during six months of field work in the area, has performed stratigraphic complementary harvest and Geology, which results are in his doctoral thesis.[9] geological mapping at a scale of 1:250,000 of [10] has drawn the geological map at 1:50,000 scale of the anticline Khangiran in Sarakhs.[11] has studied Mozduran formation depositional environment in East of Kopet Dagh.[12] have studied the geodynamic ophiolite importance in late Paleozoic rocks in the north east of Iran.[13] has studied calcareous Nannoplankton of the sedimentary sequence starting Maastrichtian-Tertiary in Sarakhs region.[14] has studied and examined the calcareous Nannoplankton of North Khorasan.

The General Geology
Abtalkh Formation is one of the most important Late Cretaceous rock units in the Kopet Dagh Basin (North East Iran).In order to study the formation, a cut was selected and sampled in the west of the Kopet Dagh Basin.The cut is located in 100 km of Gonbad-e Qabus and 35 km from the city Maravetappe in the South East of Aitamir village and north of the Cherta village.Geographical coordinates of the cut were the 37˚43'03"N latitude and 55˚35'47"E (Figure 2).

Abtalkh Formation Stratigraphy in Aitamir Cutting
(West Basin of Kopet Dagh) Abtalkh only outcrop is in the West of the Kopet Dagh basin in Aitamir Syncline.The studied section is located in the south flank of the Aitamir syncline that the syncline is located in the north part of Maraveh fault and the East of Aitamir Village.Abtalkh formation in Aitamir syncline is 675 meters calcareous shale and marl in the gray-blue color that the lower and upper boundaries have the same slope and harmonic with Abderaz Formation and the upper limestone unit (as it is called Chehel Kaman).[15] has attributed the passing through silty shales of Abtalkh formation to a thick limestone layer of the upper surface layer continuous and gradual and the limestone rock unit to Kalat formation.Abtalkh formation in the West Basin (Aitamir cutting) has dark bluish gray shale lithology with Inosramus limestone interlayers and Silica limestone interlayers.
On the Cutting,the Abtalkh formation has 489 m thickness and stratigraphic units are as follows in Figure 3: -80 meters of dark gray shale.
-50 meters of gray to bluish marl with siliceous limestone interlayers.
-19 meters gray-blue shale.320 meters of light grey shale with thin layer limestone interlayers.

Microfossils Biozonation
In this classification, a number of microfossils is expressed.Based on studies in the studied section, 9 genera were identified and photographed.The form of any fossils is at the beginning of each gender and it is then explained.
Plate 1: This Coccolith is an elliptical shape that its proximal bumper consists of two rows of calcite.Its central region lacks a certain buildings and can be seen clearly during

Biozonation of Kopet Dagh Basin
Calcareous Nannofossil is heterogeneities and a very diverse group, from the remains of calcareous plankton and includes, Coccolithophores and affiliated groups, which are the same in terms of size and chemical composition, but their relation to each other is not clear too much.So far, comprehensivestudies of biostratigraphy have been done in this basin on calcareous Nannoplankton of Cretaceous onSarcheshmeh, Aitamir, Abderaz, Abtalkh, Neyzar and Kalat have been made.Aitamir lower part formation in the cutting of Shurab [29] were studied based on calcareous Nannoplankton and the age of formation at the bottom of this section, the biozones equivalent of CC11-CC12, and considering Stratigraphy biozones introduced, the late Cenomanian-early Turonian age was proposed for this part of Aitamir formation.The upper section of Aitamir in the cut of Shurab [27] was studied and biozones Aitamir formation of CC12, CC16, CC17 was proposed andbased on stratigraphic biozones value, the section of study age is late Turonian-Late Santonian/beginning Campanian.AbDeraz Formation was studied for the first timebased on Nannofossil in type section [30] and cutting of Taherabad [31].

Conclusion
According to studies carried out on calcareous Nannofossil, the bottom part of Abtalkh formation sediment, the study section, the following results have been achieved from Figure 1.Position Kopet Dagh Basin (Nezafati, 2006).
of 28 meters below sea level to over 3000 meters above sea level.Most areas of the region have cold temperate climate.Of course, parts such as Sarakhs and Jajarm parts have a desert climate and some areas such as the southern part of Gorgan have a Mediterranean climate.The general trend of winds is in north south, but seasonal winds are blowing with east west trending in summer and west-east in winter.There are two different views about the place of Kopet Dagh zone: A) Eurasian theory in the Aq Darband Lias deposits with a clear unconformity is on the row of pyroclastic deposits with complex construction and with the Middle-Late Triassic.They know the Kopet Dagh as a part of the Eurasian continent and ultramafic rocks of Mashhad area, the remnants of an ocean.This group of geologists knows the Kopet Dagh as a part of the Eurasian continent and ultramafic rocks of the Mashhad area as the remnants of the ocean that separate two Turan (Eurasia) and Iran (Gondwana) plates from each other and has continued to the East, along the Heart fault to the Hindu Kush.B) [2] knows late-Precambrian Paleozoic rocks of Ghare bil area as the same ore deposits at the same time, in central Iran and East Alborz and believes that the Epica Tangayy platform of Paleozoic Iran are over or part of Kopet Dagh mountains.A folding model of Kopet Dagh, compared with the Zagros has been compared.According to the cases, such as high intensity of folding on the southern side, asymmetric, and steepened the southwest of the folds, it seems that the Iranian plate movement to the Kopet Dagh has a major role in the precipitate folding.Such a move has caused a mechanism change of foundation rock faults from normal to drift, with the slope to the north, and the calving strike-slip faults that matches in the direction of fault couples along the compression in the Kopet Dagh fold belt.From the middle Cambrian to the present, there are five phases of orogeny in the region.1) The beginning Kimerin orogenic that place the Kashafrud formation with age Bajocian-in the form of unconformably on late Triassic rocks in the area Aqdarband.2) The sub-Hercynian orogeny of Kalat formation that places in the Shlamy syncline in the form of unconformablyon Sanganeh Formation horizon and Aitamir.Expresses the activity of styrene is orogeny.3) Styrene orogenic, the folds of the upper layers AbTalkh Formation with Late Eocene age, or old oligo age, consistent with older formation and collapse of continental red clastic sediments, on the Khangiran the Oligocene to Miocene age in accordance with Khangiran formation, is representative of styrene orogenic activity.4) Attica Orogenic of continental clastic rocks redwith late Miocene age in the region, folded and with unconformity on the different older rocks.5) Pasadenian Orogenic the folding conglomerate with Pliocene age that place unconformably on the Red continental sediments of Miocene and older formations.Drought in an area is the same time with the major phases of the world orogeny.The first drought is at the end of Lower Cambrian and the last drought is the beginning of the Eocene age.Foundation and thrust faults are the main faults of the region.
Geological research in the Kopet Dagh has done by Grisbakhaz of India geology organization in 1881.Geologists of Amiranin Oil Company did the first systematic studies of geology and operations in the region.This enterprise geologist has studied the East and Northeast of Iran in the years 1938.1937.From 1938 to 1951, an important geological work has not been done in the area.Ganser, Switzerland, geologist, in 1951, that was employed by the national oil company, for two months of working geological, has recognized the outcrops surrounding Gorgan to Maravetappe meridian, and has prepared the geological maps in the scale of 100,000:1.Goldashmit and Fakhraei in 1952 by the National Iranian Oil Company, for two months field work, from ferns to the Maravetappe meridian with geological maps identifying the scale of 253,440:1.In 1956 Perrin and Jahanbeglo, Iranian oil company geologists' prepared stratigraphic sections in Sarakhs.

Figure 2 .
Figure 2. Illustration of Abderaz and Abtalkh formation border in the study section.
different viewpoints: During this study, for the lower part of Abtalkh formation in Aitamir cutting, a total of 9 genera were identified.Recognized calcareous nannofossils have diversity and abundance, relatively good.According to biostratigraphic, given the emergence and extinction of index species and fossil assemblages, 4 biozones were identified for the studied shear in accordance with zones (CC18-CC21) of Sysyngzon-ing, 1977.Based on the defined stratigraphic biozones value, the deposition time of the bottom Abtalkh formation is recommended the beginning Campanian to the Late Campanian.