Late Coniacian- Early Campanian planktonic foraminiferal bioevents and biostratigraphy of the northern Tunisia

• Published in: Geologia Croatica 2014-06, Vol.67 (2), p.111-126
• Main Authors: Elamri, Zaineb, Farouk, Sherif, Zaghbib-Turki, Dalila
• Format: Article
• Language: English
• Subjects: biostratigraphy; Coniacian - Campanian; Coniacian - Campanian, biostratigraphy, planktonic foraminiferal bioevents, Globotruncanidae, Heterohelicidae, Tunisia; Globotruncanidae; Heterohelicidae; planktonic foraminiferal bioevents; Tunisia
• ISSN: 1330-030X; 1333-4875
• DOI: 10.4154/GC.2014.07

Planktonic foraminifera were quantitatively analyzed across theUpper Coniacian - Lower Campaniansuccession at Jebel Ennahli and Ettout sections, northern Tunisia. This succession is characterized by hemipelagic facies domainated by a continuous sedimentary succession, allowing a good biostratigraphic correlation for this time interval. 55 planktonic foraminiferal species have been identified belonging to 13 genera. The distribution pattern of 17 heterohelicids and 38 trochospiral formsrevealsto the identification of12major bio-events and establishing three zones based on heterohelicids and five zones based on trochospiral forms. The trochospiral based zones are from base to top:Dicarinella primitivaInterval Zone,Dicarinella concavataInterval Zone,Dicarinella asymetricaTotal Range Zone, andGlobotruncanita elevata/Globotruncana arcaConcurrent Range Zone,Globotruncana ventricosaInterval Zone; while the three heterohelicid based planktonic foraminiferal biozones are:Pseudotextularia nuttalliInterval Zone,Sigalia carpaticaInterval Zone,Ventilabrella eggeri/Planoglobulina manuelensisConcurrent Range Zone. The bioevents and planktonic foraminiferal zones were correlated with the previously published works especially in Tunisia and other palaeolatitude provinces. There are no significantplanktonic foraminiferaldatums recordedacross theConiacian/Santonian boundary (CSB) except thelowest occurrence (LO) ofDicarinella asymetrica, whichwas recorded slightly below the LO of inoceramidPlatyceramus cycloides cycloidesrepresenting a good proxy for the CSB. The Santonian/Campanian boundary of the studied sections are characterized by a major turnover represented by the highest occurrence ofSigalia,DicarinellaandWhiteinellagenera; in addition tothe lowest occurrence of VentilabrellaandPlanoglobulinageneraand above slightly the LOGlobotruncanaandGlobotruncanita.