A rich ichnofossil assemblage from the Frasnian (Upper Devonian) deposits at Andoma Hill, Onega Lake, Russia

Abstract

Trace fossils and ichnofabrics were recognized in the Middle to Upper Devonian deposits of the East European Platform at the Onega Lake (NW Russia), developed as the Old Red Sandstone facies. The studied sequence is aged from the upper Givetian to the Middle Frasnian. The most diverse ichnoassemblage was ascertained in the earliest Frasnian (lower to middle part of the Andoma Formation), comprising the ichnogenera?Arenituba, Cochlichnus, Cruziana, Diplocraterion, Lockeia, Palaeophycus, Planolites, Rusophycus, Skolithos, Teichichnus, and Undichna. Combination of ichnologic and sedimentary data points to the assumption that these deposits probably originated in wave- and tide-influenced environments, possibly in a brackish-water estuary. Towards the middle Frasnian, Skolithos-like trace fossil dominate; the ichnoassemblage can be attributed to the tidally influenced channels and bars.