Ediacaran fossils from the Innerelv Member (late Proterozoic) of the Tanafjorden area, northeastern Finnmark

Abstract

AbstractAn Ediacaran assemblage dominated by an unidentified species ofCyclomedusaSprigg 1947, along with species ofEdiacaria?Sprigg 1947,BeltanellaSprigg 1947,HiemaloraFedonkin 1982, andNimbia?Fedonkin 1980, is described for the first time from the Innerelv Member of the Stappogiedde Formation exposed in coastal outcrops west of Tanafjorden on Digermul Peninsula, in northeastern Finnmark, northern Norway. The fossil assemblage is dominated by discoidal forms which share certain affinities with the cosmopolitan genera.CyclomedusaandEdiacaria. However, our specimens differ from these and other discoidal Ediacaran fossils in the absence of radial sculpture. This, along with a basically concentric organization, are characteristics shared withKullingiafrom the Dividal Group of northern Scandinavia, the White Sea, Podolia, and northwestern Canada, along with undescribed discoidal remains from the Charnian Supergroup, Charnwood Forest, Leicestershire, England, and the Conception Group, Avalon Peninsula, Newfoundland.Our discovery of an Ediacaran-type assemblage within the Middle Innerelv Member provides support for previous suggestions of a late Vendian age for this sequence. This general conclusion is consistent with the occurrence of early Cambrian taxa, including the trace fossilPhycodes, and the problematical formsVendotaeniaandSabellidites,in basal portions of the Lower Breivik Formation, within the same stratigraphie section. The lowest formally-proposed faunal zone in northern Scandinavia is theKullingiaZone, based on the occurrence of the fossil medusoidKullingia concentricain Member III (Middle Sandstone C) of the Dividal Group, northern Scandinavia.Kullingiais a distinctly chambered form that was probably pelagic. In contrast,Cyclomedusa,and related genera of the so-calledCyclomedusaplexus, comprise an informal grouping of intergrading, probably benthic, taxa that possess radial and/or concentric organization. In light of the intergradational nature of taxa, present difficulties in taxonomic interpretation and correlation, and the abundance of cyclomedusoids in many Ediacaran assemblages, we suggest that the concept of theKullingiaZone, as originally defined for northern Scandanavia, be broadened to include the common form genera of theCyclomedusaplexus, inclusive of the occurrences in the Innerelv Member described herein. It is our hope that additional fieldwork will provide a basis for more refined taxonomic evaluations and biozonation.