Writers : Sanaie, Najme; supervisor: R. Moussavi Harami, A. Mahboobi; advisor:M. Nagafi
Refference : M.Sc. Thesis; Ferdowsi university
Publishing Year : 1382

Abstract :

The Kopet_Dagh basin is located in NE Iran. This basin formed after the Early Kimmerian Orogeny and more than 6000 meters of sediment were deposited from Jurassic through Miocene, with any the eastern part of the major break in the eastern part of the basin. The purpose of this study is to interpret the depositional history and stratigraphic sequence of the Tirgan Formation Barremian-Aption in age. In the castrnmosi part of the basin, the Tirgan Fomation is composed of oolitic limestone with interbedded calcareous shale (marl) that overlying silisiclastic Shurijeh Formation and underly by pencil marl of the Sarchcshmeh Formation. 12 stratigraphic sections were measured and their thicknesses range from 20 to 4.5 meters. The limestones arc mainly thin to medium bedded with skeletal and nonskeleta grains.The silisiclastic sediments (sandstones) are present in the ,lower parts of the formation
Petrographic studies of 110 thin sections showed that the carbonate� rocks consists of 5 facies assemblage. Carbonate facies consists of 11facies Biomicrite, Bioclastic-oomicrite, Oomicritc, Biosparit (Bioclastic-oosparite, Bryozoaz-biosparitc,Oosparitc, Pelsparite Orbitolina biosparite, Micrite and Dolomite). that are deposited in a carbonate platform (shelf) in open marine, barrier, lagoon and tidal flat environments. Silisiclastic lithofacies are composed of sandstones and calcareous shales that may have been deposited in a shoreline environment.
Diagenctic processes wich acted upon the carbonate rocks consists of micritization, cementation, geopetal, compaction, stylolitization. dolomitization and fracturing that operating in deagenctic environments including marine phreatic, meteoric phreatic,burial and uplifting.
Sequence stratigraphic studies show that sediments in the all measured the sections formed one depositional sequence (DS) with� lower S131 boundary and upper SB2 boundary types. Palcogcographic of Tirgan Formation during the Lower Cretaccous in the study area has been interpreted in live stages from Neocomian to Aptian.

Subject List : Depositional history