Middle Ordovician cephalopods from the Abarsaj area, northern Iran

Four cephalopod taxa are recognised from a locality near the village of Abarsaj, eastern Elborts of northern Iran. The new fossil locality is in the Abastu Formation, which is made up of a basal white to light pink sandstones which pass up into thin-bedded brownish limestone, then into interbeds of grey to green limestones and shales, and dolostones at the top. The Formation is 140 m thick. Contacts with the underlying late Cambrian Mila Formation and the overlying Katian-Hirnantian Abarsaj Formation are unconformable. In Abarsaj, all cephalopod specimens were collected from the middle part of the section, represented by thin-bedded brownish limestone, at 80 m above the basal unconformity. The described fauna includes Proterovaginoceras ?incognitum, Eosomichelinoceras n. sp., Sactorthoceras n. sp. and Orthocerida indet suggesting the late Dapingian to Darriwilian (Middle Ordovician) age for the strata. The reported assemblage belongs to an assemblage of an open water fauna and suggests a close affinity with those of Baltica and South China.