A diverse ichnofauna and its palaeoenvironmental significance from the Upper Jurassic Argiles de Saïda Formation (Northwestern Algeria)

ABSTRACT

Forty-three ichnospecies belonging to 30 ichnogenera are described from the Upper Jurassic Argiles de Saïda Formation (north-western Algeria), which consists of mixed shallow marine siliciclastic-carbonate sediments. The ichnological analysis reveals that the majority of the ichnoassemblages are represented by non-graphoglyptid traces dominated by Bergaueria isp., Ophiomorpha isp., O. rudis, Neonereites biserialis, N. triserialis. Furthermore, Chondrites isp., Palaeophycus isp., Phycosiphon isp., Planolites isp., Protovirgularia isp., Scolicia isp. and Thalassinoides isp. are common ichnotaxa. Ancorichnus isp., Archaeonassa isp., Gordia isp., Helminthoidichnites isp., Helminthopsis isp., Nereites isp., Ophiomorpha annulta, Oravaichnium isp., Oravaichnium hrabei, Protovirgularia dichotoma, Rutichnus rutis, Thalassinoides suevicus are rare, whereas, Chondrites targionii, Nereites irregularis, Neonereites uniserialis, Ptychoplasma excelsum, Spongeliomorpha isp., Taenidium isp., Taenidium serpentinum, ?Tubulichnium isp. and Zoophycos isp. are rare to scarce ichnotaxa. The graphoglyptid assemblage has very low diversity with only three ichnotaxa which are Megagrapton isp., Megagrapton submontanum and Scolicia strozzii. The described ichnoassemblages are assigned to the Cruziana to Cruziana-Nereites ichnofacies transition.

KEYWORDS:

• Upper jurassic
• Argiles de Saïda
• Algeria
• non-graphoglyptid
• Cruziana-Nereites ichnofacies

Acknowledgments

The authors thank the Editor-in-Chief Gareth Dyke for suggesting corrections and modifications. Authors are also thankful to Alfred Uchman for his helps in the determination of some trace fossils. We are especially grateful to Dirk Knaust and two anonymous reviewers for their critical review of the manuscript. Tuna Eren is gratefully acknowledged for his help in revising the language of the manuscript.

Disclosure statement. This is to acknowledge any financial interest or benefit that has arisen from the direct applications of our research.

Disclosure statement

No potential conflict of interest was reported by the author(s).