The biostratigraphy and palaeobiogeography of the Late Jurassic dinoflagellate cysts from the Binalud Mountains, NE Iran

Abstract

This study investigates the dinoflagellate cysts from the upper part of the Dalichai Formation in the Binalud Mountains (NE Iran, western Tethys), where the deposits are primarily consist of shale and marlstone layers. The analyzed section yielded common and diverse dinoflagellate cyst assemblages comprising 46 species belonging to 33 genera. These assemblages are correlated with the DSJ24–DSJ33 dinoflagellate cyst Zones of the Late Jurassic (late Oxfordian–Tithonian) in the Northern Hemisphere. Key bioevents identified in this interval included the last occurrences of Compositosphaeridium polonicum in the late Oxfordian, the last occurrence of Ctenidodinium ornatum at the Oxfordian–Kimmeridgian boundary, the last occurrences of Tubotuberella eisenackii and Scriniodinium crystallinum in the early Kimmeridgian, and the last occurrence Endoscrinium luridum around the Kimmeridgian–Tithonian boundary. The dinoflagellate cyst assemblages exhibit strong similarities to the flora of the western Tethys (the Middle East, Europe, eastern North America, and North Africa) and are marked differences from coeval assemblages of the eastern Tethys (Australasia, eastern Asia, and northeastern India), reflecting significant provincialism between the western and eastern Tethys during the Late Jurassic.