فهرست مطالب میرامیر صلاحی

In the present study, In order to study of the planktonic foraminiferal biostratigraphy of Qom Formation in north of Khoy city, West Azarbayjan province (Sanandaj-Sirjan fore-arc basin), stratigraphic section of Sagatlu was selected and sampled. Thickness of Sagatlu section 216 meters was measured. Lithology of this section contain shale, siltstone, conglomerate and sandstone. The lower boundary of these deposits is alluvium, and its upper boundary is hard limestone deposits of Qom Formation. Study of the planktonic foraminifera communities found in the mentioned section to identify 16 genera and 37 species of planktonic foraminifers. In this research, 4 biozone are included, Subbotina linaperta assemblage Zone, Paragloborotalia opima Highest-occurrence Zone, Ciperoella ciperoensis Partial-Range Zone, Globigerinoides italicus assemblage Zone were identified as being age equivalent to Priabonian-Burdigalian and comparable to world standard biozones..

To separate the different units of the Paleogene sequences of the Kopet-Dagh basin and their regional correlation with the adjacent areas in the Central Asia, the Oyster bivalves fossils are used in the current research. Also, the study of their paleobiogeography has been considered in this study. Based on this fauna, Pycnodonte-Oestra community in the Chehelkaman Formation uppermost parts represents the late Paleocene age and the first occurrence of Flemingostrea hemiglobosa at the base of the Khangiran Formation confirms the beginning of Eocene epoch. Association of different species and subspecies of Turkostrea in the Khangiran Formation demonstrates the middle part of early Eocene and Sokolowia community near the top of the Khangiran Formation shows the Lotetian-Bartonin ages. These features are in full compliance with the bivalve communities recorded from the other parts of Central Asia such as Amu-Darya, Farghana, Afghan - Tajik and Trim basin of China. It illustrates the same geological history of the mentioned areas during Paleogene, indicates the occurrence of different types of molluscan taxa in the Kopet-Dagh basin is the same as parallel horizons and equivalent time units throughout the extensive Central Asian region.

Considering that detail paleontological and sedimentological studies have not been carried out on the northern Nourabad area, this study is based on measured stratigraphic section of the Haft- Cheshme to evaluate and analyize the parameters such as biostratigraphy and sedimentary environments of Miocene deposits, inorder to gain the new information about the geology of the area. In this study, large benthic foraminifers used to identify the biozones and determine the age of these deposits. On the other hand, in order to obtain new information on the formation of these deposits, the study of sedimentary environment was also discussed. For detail study of these deposits, sampling were done at 1 meter interval. A total of 100 samples were collected from a thickness of 127 meters. The sedimentary facies are named based on Flugel (2010) classification. Also, in the designation of carbonate facies, Dunham (1962) and Ambry and Klovan (1971) have been used for the classification of carbonate facies. The lower boundary of Miocene deposits in this section is sharp with Mc unit of ophiolitic complex and the upper boundary is erosional. Based on the studies of the larger benthic foraminifera assemblages, 18 genera and 20 species were identified which represent the Borelis melocurdica- B. melo melo assemblage zone and suggest a Burdigalian age. Also based on the field observations, petrographic studies and textural characteristics as well as the abundance and distribution of foraminiferal fauna and other components, 14 carbonate microfacies have been identified. These carbonate microfacies were deposited in 5 facies belts including lower slope facies, upper slope facies, margin facies, platform-margin sand shoals and lagoon. The existence of coral barrier reefs, intraclasts, aggregate grains and the sudden facies changes and also the absence of vast areas of intertidal flat represent that this sequence deposited on a rimmed carbonate platform.  Also based on the petrographic studies of Bouma Ta and Tb divisions and the existence of the sedimentary structures such as Bouma Ta division (re-deposited carbonates, calciturbidites), the studied section has been deposited on a rimmed carbonate shelf.

Kopet-Dagh basin is located in north and northeast of Iran. Chehelkaman and Khangiran Formations are the most important formations of Paleogene settings. Upper parts of Chehelkaman Formation in the Chehelkaman Syncline section consist of sandy limestone, marl and limestone with transition contact into Khangiran Formation is conformable and transitional. In this study depositional condition of the top of Chehelkaman Formation and base of Khangiran Formation based on gastropod fauna and trace fossils were studied. These trace fossils in accosiation with tidal flat and lagoon facies that indicate of depositional in the shallow depth environment. Also in this study Globularia genus from Ampullinid gastropods for first time recognized of Kopet- Dagh basin.Because of this genus related with lagoon facies, can be indicate of shallow depth environment for the top of Chehelkaman Formation too. Paleobiogeography of this genus indicates of dependency of Kopet- Dagh basin to tethys realm. So far this genus reported of parts of Central Asian, Eastern Europe, Central Europe and Western Europe. This genus is in the top of Chehelkaman Formation of Kopet-Dagh basin, whearas this genus reported in the layer of post Early Eocene in Erope. This subject indicates migration direction of this genus from east toward west. So can be elicitation that the turan basin is the easternmost of the presence and occurrence of this taxon. In duration of this migration direction from east to west, Anatulian basin of Turkey exposure in the middle of this migration direction.

Kopet-Dagh basin is located in north and northeast of Iran. Khangiran Formation is one of the most important formations of Paleogene deposits. For study of Khangiran Formation, Chehelkaman Syncline section was selected. This section located in southwest of Sarakhs city, east of Kopet-Dagh basin. Thickness of this section is 136 meters and lithology of this section composed alternation of olive green Marl and limy yellow Marl. In this research foraminifera fauna of Khangiran Formation was studied. The age of this section is Early-Middle Eocene, and planktonic foraminifera fauna of this section shows anomaly. Based on this anomaly, lack of Morozovellids, that are index fossils of Eocene, was observed. Eutrophic condition of this Formation as for the planktonic and benthonic foraminifera study is the reason of this subject that it's the result of changes in the paleoceanographic conditions such as situation of stratification of water column and nutrient changes. As far the Morozovellids cant accordance with eutrophic condition, lack of the species mans of this genus observed for Khangiran Formation. Khangiran Formation condition is comparable with Caucasus basin and this subject can be indicating of same condition of this two basin at least during the Eocene time.

Kopet-Dagh basin is located in north and northeast of Iran. Khangiran Formation is one of the most important Formations of Paleogene deposits. For study of Khangiran Formation bivalves, Chehelkaman Syncline section has been selected. This section located in west of Sarakhs city, east of Kopet-Dagh basin. Lithology of this Formation in the Sarakhs region composed of marl, marly limestone and siltstone. In addition lithology of deposits with oyster shells consists of 50m olive green monotonous marl with large shells of oysters that are very well preserved. Based on this shells study, species of Sokolowia beldersaiensis and Sokolowia buhsii of Ostreidae family have been recognized. These shells indicate sub-tidal to shallow marine environments and euhaline waters and proposed Middle Eocene age (Bartonian stage) for these sediments. Furthermore, paleobiogeography survey of this bivalves indicate dependency of Khangiran Formation to Tethyan realm, that this realm limited to central Asian region and located between Transylvanian basin of Romania, in the west and Tarim basin of China in the east. Retreat of this sea in the Middle Eocene cause of oyster shells composed in the Bartonian stage. These shells indicate dependency of Kopet-Dagh basin to Turan Sea that this subject causes of strengthens of Urasian theory of Kopet-Dagh basin.