Ichnofossils of Sarcheshmeh Formation (Aptian) at Khur Syncline (North of Mashhad) and their application in environmental interpretation

Sarcheshmeh Formation (Aptian) exposed in the Khur syncline with northwest- southeast trend, (eastern Kopet-Dagh zone). It mainly consists of shale, calcareous shales and thin bedded limestones with trace fossils. Sarcheshmeh Formation overly conformable on Tirgan Formation and its upper boundary is eroded in this section. For basin analysis based on ichnofossils, a lithostratigraphic section in the Khur syncline (N Mashhad) was selected and studied. Five ichnogenera; Paleodictyon, Zoophycos, Scolicia, Arthrophycus, Chondrites, and three ichnospecies; Paleodictyon maximum, Paleodictyon strozzi, Paleodictyon miocenicum, were identified. Sarcheshmeh Formation has been interpreted as a shallow marine deposite, it may be, however deposited in the deeper environment such as, outer ramp with lower oxygen level, where these ichnofossils formed