Trace fossils from the Berriasian-Valanginian of the Ouarsenis Range (northwestern Algeria) and their paleoenvironmental implications

The Berriasian-Valanginian succession cropping out in the Ouarsenis Range (northwestern Algeria) consists of ammonite-bearing, marlstone-limestone alternations, herein divided into four informal units (A to D) at the Ain El Hadjela section. These lithostratigraphic units encompass five standard Mediterranean ammonite zones of late Berriasian to late Valanginian age. In this study nine ichnotaxa are documented: Chondrites intricatus, Palaeophycus isp., Planolites isp., Rhizocorallium commune, Thalassinoides isp.; Thalassinoides suevicus, Tisoa siphonalis, Zoophycos isp. and Zoophycos brianteus, reported for the first time from the early Cretaceous of Algeria. These traces are characteristics of the Zoophycos ichnofacies, representing deep and oxygen-restricted environments. This ichno-association together with litho-biofacies contents are suggesting deepening from deeper part of platform to the basin environment as identified in previous studies of the same time interval through the Mediterranean region.

Automated summary

The study explores the lithostratigraphic units and ichnofacies characteristics of the Berriasian-Valanginian succession in northwestern Algeria, showcasing nine ichnotaxa for the first time in the early Cretaceous of Algeria. This ichno-association suggests a deepening environment from the platform to the basin as seen in previous studies in the Mediterranean region during the same time interval.