Planktonic foraminiferal biostratigraphy and paleoecology of Upper Cretaceous deposits from the Palmyride Region, Syria
Planktonic foraminifera were quantitatively analyzed across the Santonian succession and their boundaries at the Jebel Ennahli and Ettout sections, northern Tunisia. The continuous sedimentary succession is dominated by hemipelagic facies, allowing a good biostratigraphic correlation for this time interval. Fifty-fi fe planktonic foraminiferal species belonging to 13 genera have been identifi ed. The distribution pattern of 17 heterohelicids and 38 trochospiral forms reveals the identifi cation
... the identifi cation of 12 major bio-events and allows establishment of three zones based on heterohelicids and fi ve zones based on trochospiral forms. Trochospiral based zones are from the base to the top: 1) Dicarinel la primitiva Interval Zone, 2) Dicarinella concavata Interval Zone, 3) Dicarinella asymetrica Total Range Zone, 4) Globotruncanita elevata/Globotruncana arca Concurrent Range Zone, and 5) Globotruncanita ventricosa Interval Zone. The heterohelicid planktonic foraminiferal zones are: 1) Pseudotextularia nuttalli Interval Zone, 2) Sigalia carpatica Interval Zone, and 3) Ventilabrella eggeri/Planoglobuliina manuelensis Concurrent Range Zone. The bioevents and planktonic foraminiferal zones were correlated with previously published works especially on Tunisia and other areas. The lowest occurrence (LO) of Dicarinella asymetrica is the only planktonic foraminiferal datum recorded across the Coniacian/Santonian boundary (CSB). It occurs slightly below the LO of the inoceramid Platyceramus cycloides cycloides representing a good proxy for the CSB. The Santonian/Campanian boundary in the studied sections is characterized by a major faunal turnover represented by the LO of Ventilabrella and Planoglobulina and the LO of Globotruncana and Globotruncanita slightly above. The boundary interval is also characterized by the highest occurrence (HO) of Sigalia, Dicarinella, and Whiteinella.