The first report of Pteropods of Limacinidea Superfamily from Khangiran Formation and their paleobathymetry significance in comparison of foraminifera

The studied section exposes in Chehel Kaman synclinal entrance in east of Kopet-Dagh basin. A small collection of fossil pteropods، referred to as Limacinidea superfamily، is reported from the lowermost portion of Middle Eocene sediments of Khangiran Formation. This is the first record of fossil pteropods from this formation. This research was led to identification of 3 species from 2 pteropod genera. On the basis of these Pteropods، the age of these sediments are Lutetian. These planktonic gastropods occurrence have paleoecological importance because pteropods dispersion is affected by environmental factors such as water temperature، salinity، depth and oxygen content. Based on these pteropods and calculation of the depth on the basis of planktonic and benthic foraminifera، it can be interpreted that the palaeo depth was about ~500 m for the sediments containing pteropod. Their presence along with foraminifera in the Khangiran Formation indicates deposition in an open sea basin above aragonite compensation depth.