Writers : Mahboobi, Asadollah; Moussavi Harami, Seid Reza; Najafi, Mahdi; Mansoori Daneshvar, Parviz
Refference : Geosciences Scientific Quarterly Journal,No.58
Publishing Year : 1385

Abstract :

The Kopet-Dagh sedimentary basin, formed as an intracontinental basin in the northeast of Iran, is characterized by a relatively continuous sedimentation that occurred during the Jurassic to Miocene. Petrographic study of Kalat Formation limestones (Late Maastrichtian) in three measured stratigraphic sections (Kalat Syncline entrance, Khesht Village and Tang-e-Chahchaheh) led to the identification of 16 lithofacies. It could be interpreted that these lithofacies were deposited in a carbonate ramp in restricted lagoon, lagoonal bar, semirestricted lagoon, barrier bank and open marine environments, It is also suggested, based on lithofacies analysis that the maximum transgression was occurred in Tang-e-Chahchaheh area (section 3). Sequence stratigraphic analysis revealed two depositional sequences in sections 1 and 2 and three depositional sequences in section 3. In all sections, the lower boundary of Kalat Formation with Neyzar Formation (paleosol layer) and its upper boundary with Pestehligh Formation (continental deposits) are type 1 sequence boundary; while other boundaries within the Kalat Formation are type 2. Correlation of interpreted sea level curve of the Late Maastrichtian time with the worldwide curve shows the type I sequence boundaries are comparable with each other. However, some differences can probably be related to regional tectonic setting of the Kopet-Dagh basin due to subsidence along the northeast-southwest longitudinal faults (mostly in sections I and 2) and sediment loading. Paleogeographic reconstruction of the Late Maastrichtian time shows that the sedimentary rocks of Kalat Formation were formed in six stages of transgression and regression. This information can help in better understanding of the Maastrichtian paleogeography of the entire basin in NE Iran.

Subject List : sea level history, stratigraphy