فهرست مطالب سید علی آقانباتی

The present study is the first study aimed at biostratigraphy based on calcareous nannoplankton that has been performed on all succession exposed from the Oligo-Miocene marine deposits (members a to f of the Qom Formation). The studied deposits are located in the middle part of the Central Iran Zone and more precisely in the Navab anticline (northeast of Kashan city), which has a thickness of 417 meters. Due to the location and expansion of all members in this section, it has been a very suitable area for biostratigraphic assessments comparable to world standard models. In this study, a total of 370 microscopic slides prepared from rock samples were studied to the determination of the calcareous nannoplankton and accurately separate world standard biological zones, which led to the identification of 72 species belonging to 18 genera of this valuable group of the planktonic micro-organisms. According to the identified index species, standard nannoplankton biozones of the NP25 and NN1-NN4 were separated from this surface section of the Qom Formation. In addition, the equivalent biozones such as CNO5-6, CNM1- CNM6 as well as zones and subzones CP19b, CN1a, b, c, CN2- CN3, which belonging to the newest biozonation patterns, were also separated in this study. Therefore, based on the geological time value of the separated biozones, the age of late Chattian to late Burdigalian-early Langhian was proposed for the Qom Formation in the Navab anticline section. In this study, for the first time, the important chronostratigraphic boundaries such as the Paleogene-Neogene system boundary (or Chattian-Aquitanian stage boundary) in the upper parts of sub-member "c1", the Aquitanian- Burdigalian stage boundary at the base of member "e" and Burdigalian- Langhian in the upper part of member "f", were disaggregated based on biostratigraphic criteria.

The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These sediments are formed in an open shelf and under the open sea and lagon environment. The variety and abundance of bentic foraminifer’s forms and the low presence of plagic forms testify to the shallow basin in this section, which is also confirmed by the study of other fossils. One of the Markable features of this section is the presence of Ammonia species, especially Ammonia parkinsonia. This section has a complete sequence of members of Qom Formation. This species are profe of shallow water and continental shelf for this carbonates. This section consist all of members of Qom Formation and based on identified foraminifera comparable to assemblage zone 1 & 2 introduced by Adams & Bourgeois (1967). These zones that inclod: 1-Borealis Melo Group- Meandropsin; 2- Miogypsinoides- Archaias- Valvulinid. Based on index foraminifer's species and their stratigraphic distribution the age of this section is Chatian- Burdigalian (Upper Oligocene-Lower Miocene)

The Kopet-Dagh Basin in northeast Iran, is an inverted basin (Allen et al., 2013) extending from the east of Caspian Sea to NE Iran, Turkmenistan and north Afghanistan (Afshar Harb, 1979; Buryakovsky et al., 2001). This basin separates Central Iran from the Turan plate (Alavi et al., 1997). Following the closure of Palaeo-Tethys in the Middle Triassic (Alavi et al., 1997) and the opening of Neo-Tethys during the Early to Middle Jurassic (Buryakovsky et al., 2001), the Kopet Dagh Basin formed in an extensional regime during the Early to Middle Jurassic (Garzanti and Gaetani, 2002). The objectives of this study are facies analysis and depositional model of the Tirgan Formation in the study areas.

In this study, 3 outcrop sections from the Tirgan Formation (Fig 1), were measured bed-by-bed, and samples were taken systematically. Over 524 fresh carbonate samples were collected, from which 500 thin sections were made. Carbonates were classified using the Dunham (1962) scheme. Siliciclastic rocks were classified using the Folk (1980) scheme.

Petrographic studies in the study area, 17 different microfacies types have been distinguished in four facies belts including tidal-flat, lagoon, shoal, and open marine and 2 petrofacies including subarkose and quartzarenite. According to the field observations, petrographic studies, and comparison of vertical and lateral changes of the facies, the carbonate facies assemblage was deposited in a homoclinal carbonate ramp, while the siliciclastic lithofacies were deposited in tidal environments at high detrital entry rates.

The Baghuk mountain section located in 50 km North- East of Abadeh, is studied regarding conodonts for the first time. The Abadeh locality is one of the most important area for analyzing the Permian-Triassic boundary in Iran. considering abundance of Conodonts in this section, Clarkina orientalis, has been identified for termination of Wuchiapingian or Dzhulfian and 7 Conodont biozones 1-Clarkina subcarinata 2-Clarkina changxingensis 3-Clarkina bachmnni 4-Clarkina nodosa 5-Clarkina abadehensis 6-Clarkina yeni 7-Clarkina hauschkei and 3 rock units lacking index fossil for Changhsinghian or Dorashamian and two conodont biozones including 1-Hindeodus parvus-Isarcicella staeschei 2-Isarcicella isarcica for base of Triassic, Griesbachian (Induan). Considering the age range, concluded studying Baghuk section, this region is comparable with some sections in the world such as South china, India, Alps, North Caucasus and regions in Iran such as north west of country, Amol, Shahreza (Shahzadeh Seyed Ali Akbar) and Hambast. Accomplished studies and type of fossils regarding bathymetry and existence of stromatolites structures, shows the shallow depths of the basin at the Permian- Triassic boundary.