Paleoecology of Abderaz Formation at type section based on foraminifera

Abderaz Formation (Turonian-early Campanian in age) at its type section has a thickness of 300 m and contains light grey shale and marl. The study of the planktonic foraminifera in isolated form resulted in differentiating three morphotype groups. Also the planktonic to benthic (P/B) and infaunal to epifaunal ratios show that the water depth increased in the region at the end of Turonian and then decreased to less than 100meters in Coniacian. Increasing the water depth at the Coniacian-Santonian boundary and achieving has been observed as well as a deep diminishing trend to the end of the formation. Curves of morphotypes changes are in full agreement with the curves of the sea level changes and P/B. Frequency of epifauna to infauna morphotypes was used to reconstruct the oxygen level and food supply. At the base of section increase in the epifauna morphotypes indicate high oxygen condition and low food supply. In the middle part, decrease in epifauna to infauna ratio is indicative of low oxygen condition andhigh food supply. At top of the section, similar condition to that of the lower part is observed. Planktonic foraminiferas of Abderaz Formation are indicative of the Tethyan provinces.