Lithostratigraphic and facies analyses of the Sarcheshmeh Formation (LowerCretaceous) in the eastern Kopet Dagh Basin, NE Iran

The Kopet Dagh Basin is located in north-east Iran where sedimentation cont inued throughout the Jurassic-Tertiary. The area studied is in the easternm ost part of the basin. Two stratigraphic sections representing mainly the L ower Aptian Sarcheshmeh Formation have been measured. The Sarcheshmeh Forma tion in one of these sections (Mozduran) is about 200 m thick. It thins tow ards the other section (Baghak) in easternmost part of the basin where it a bout 150 m thick. It is conformably overlain by the Sanganeh Formation and underlain by the Tirgan Formation. Four different facies have been recogniz ed; pelmicrite, mudstone-micritic limestone, biomicrite-bio-oomicrite and b iosparite-oosparite. They reflect deposition on a carbonate ramp. Many smal l-scale shallowing-upward cycles (parasequences) have also been identified within transgressive and high stand system tracts. The cyclicity was probab ly related to subsidence, which in rum was related to both sediment loading and tectonics. (C) 2000 Academic Press.