Original paper
Diverse Chondrites and associated trace fossils from the Lower Cretaceous Oued Fodda Formation at its type locality (Ouarsenis Range, Tell Atlas, Algeria)
Berrabah, Ali; Cherif, Amine; Naimi, Mohammed Nadir; Zeghari, Ahmed; Adaci, Mohammed
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 313 Heft 3 (2025), p. 327 - 340
74 references
published: Feb 16, 2025
published online: Feb 3, 2025
manuscript accepted: Jan 3, 2025
manuscript received: Oct 22, 2024
ArtNo. ESP155031303006, Price: 29.00 €
Abstract
The Lower Cretaceous Oued Fodda Formation is widely distributed in the Ouarsenis Range. In its type section, located at Koudiat Larouah, this formation revealed abundant and diversified Chondrites burrows, including C. cf. affinis, C. intricatus, C. recurvus, C. targionii, and another Chondrites ichnospecies, that remains in open nomenclature. The associated ichnofauna includes Palaeophycus isp., Phycosiphon incertum, Planolites isp. and Zoophycos brianteus. Chondrites and Zoophycos are the most abundant ichnogenera in the studied section. The ichnoassemblage is exclusively dominated by post-depositional traces, representing both deep-tier (Chondrites and Zoophycos) and shallow-tier (Phycosiphon) infaunal communities formed by opportunistic colonisers. This ichnoassemblage closely resembles that of the Aïn El Hadjela section and is attributed to the Zoophycos ichnofacies, dominated by fodinichnial components mainly produced by vermiform organisms. The low ichnodiversity observed in this section may be related to dysoxic stress conditions in a deep environment, likely due to oxygen deficiency. The beginning of the deepening phase and oxygen deficit is recorded around the Berriasian-Valanginian boundary with the first appearance of Zoophycos, in association with Chondrites. The dysoxic conditions are confirmed by the presence of pyritised ammonites and pyrite nodules.
Keywords
Berriasian–Valanginian • deep environment • Zoophycos ichnofacies • dysoxic • opportunistic colonisers