Writers : Zohreh Sohrabi; Supervisors: B. Hamdi, A.Aghanabati; Advisers: A. Saeedi, M. Sahandi
Refference : Msc. Thesis
Publishing Year : 1384

Abstract :

In this thesis, the Upper part of Shishtu, Sardar and Jamal Formations in the Zaludu section, located in Ozbak kuh area in the north of Tabas Basin, East of Iran were studied. Three members and 26 lithostratigraphic units in Sardar Formation, and three members and 16 lithostratigraphic units in Jamal Formation were determined on the basis of lithostratigraphic studies. According to the biostratigraphy studies on the foraminifera and conodonts obtained from the Sardar Formation, index species from limestone layers could offer Late Visean (V3c) - Late Moscovian age. Moreover, index species of foraminifera and conodonts from sedimentary rock layers that belong to Jamal Formation could offer Late Carboniferous (Early Gzhelian) - Early Permian (Middle Asselian) age. In accordance with the lithostratigraphic and biostratigraphic studies on Shishtu, Sardar and Jamal Formations and also the border of these formations, it seems that the above and below borders of Sardar and Jamal Formations are discontinuous and have disconformity in which the bedding planes above and below the stratigraphic break are essentially parallel. Disconformity between Shishtu and Sardar Formations is probably related to erosional period of Alborzian phase that occurred near the end of Late Visean or maybe due to the global climatic event phenomena. Disconformity between Sardar and Jamal Formations is probably related to the worldwide sea water level changes due to the glacier expansion in Late Carboniferous; at that time glacier spreading mass had occupied the vast area of Gondowana supercontinent. Furthermore, based on biostratigraphic studies on the foraminifera, 6 zones and 3 sub zones in the Sardar Formation, 2 zones in Jamal Formation., and according to biostratigraphic studies on the conodonts, 4 zones in Sardar Formation., and 4 zones in Jamal Formation were identified. These zones from the below toward the top of Sardar Formation are as follow: Foraminiferal biozonations in Sardar and Jamal Formations are follows:
1) Asteroarchaediscus baschkiricus - Pseudoendothyra struvei Zone.
2) Asperodiscus iranicus - Ammovertella inversa Zone.
3) Eostaffella pseudostruvei - Eostaffella mirifıca Zone.
4) Eostaffellina paraprotvae - Endothyra baschkirica Zone.
5) Pseudostaffella compressa - Pseudostaffella antiqua _ Eostaffella amabilis Zone.
6) Ozawainella mosquensis-Pseudostaffella subquadrata Zone.
6-1) Eostaffella acutissima-Eostaffella lepida Subzone.
6-2) Profusulinella parva-Profusulinella prisca Subzone.
6-3) Pseudostaffella sphaeroidea - Schubertella sp. Subzone.
7) Triticites parvus - Triticites truncatus Zone.
8) Pseudoschwagerina sphaeroidea Zone.
These two latest zones belong to Jamal Formation. Conodont biozonations in Sardar and Jamal Formations are as follow:
1) Declinognathodus noduliferous Zone.
2) Idiognathoides corrugatus - Idiognathoides sulcatus /Idiognathoides sinuatus-Idiognathodus primulus Zone.
3) Idiognathoides sulcatus parva Zone.
4) Ferganaegnathodus ferganaensis-Idiognathodus delicatus Zone. these 4 bio zones are recognized in Sardar Fm.
5) Streptognathodus?? elongatus Zone.
6) Streptognathodus tenuialveus Zone.
7) Streptognathodus?? isolatus Zone.
8) Streptognathodus?? cristellaris Zone. These 4 biozoens are recognized in Jamal Fm. In these section With regards to the lack of Streptognathodus wabaunsensis Zone, it seems that the boundary between Carboniferous and Permian at least in this sectoin was probably continous.
According to these studies about 45 geniuses, 122 species and subspcies from foraminifera, 3 geniuses and 4 species and 7 geniuses and 27 species from conodonts are recognized from two formations that many of them are reported for the first time from Iran. These species are as follows:
Streptognathodus elongatus, Streptognathodus parvus, Streptognathodus bellus, Streptognathodus tenuialveus, Streptognathodus isolatus, Streptognathodus wabaunsensis, Streptognathodus nodulinearis, Streptognathodus aff. flexusous, Streptognathodus acuminatus, Streptognathodus rectangularis, Streptognathodus invaginatus, Streptognathodus cristellaris, Streptognathodus glenisteri, Streptognathodus flangulatus, Streptognathodus sigmoidalis, Streptognathodus longissimus.

Subject List : Biostratigraphy