First record of trace fossils in the Ediacaran–Cambrian transition on the northern Gondwana platform (Anti-Atlas, Morocco)

Abstract

The Anti-Atlas Mountains of Morocco preserve one of the most complete latest Neoproterozoic to Cambrian stratigraphic successions worldwide, with high-resolution chemostratigraphic δ13Ccarb coverage. However, the exact stratigraphic position of the Ediacaran–Cambrian boundary remains unresolved. Until now, no trace fossils or body fossils have been recorded from the terminal Ediacaran strata in the Anti-Atlas Mountains. The only exception is a discoidal body fossil-like structure from the shallow-marine sandstones of the Ediacaran Tabia Member, Adoudou Formation, in the Taroudant Group in the Igherm inlier. For the first time, we document the occurrence of abundant trace fossils from the base of the Adoudou Formation, including Treptichnids, Monomorphichnus isp., Helminthoidichnites isp., Gordia isp., Palaeophycus isp., Planolites isp., and Conichnus isp. The integration of both trace fossils and carbon isotope δ13Ccarb records suggests that the Ediacaran–Cambrian transition in the Sous Basin can be placed at the contact between the Tifnout and Tabia Members, which chemostratigraphically coincides with the large negative δ13Ccarb excursion that had been previously suggested for the Ediacaran–Cambrian boundary (BACE) in the western Anti-Atlas Mountains.