Scratch circles from the Ediacaran and Cambrian of Arctic Norway and Southern Africa, with a review of scratch circle occurrences

Abstract

Scratch circles – bedding plane parallel sedimentary structures formed by the passive rotation of a tethered organism into the surrounding sediment – are relatively rare in the geological record. Here new occurrences of scratch circles are described from the Ediacaran–Cambrian Stáhpogieddi Formation, Digermulen Peninsula, Arctic Norway, and from the Ediacaran Nudaus and Urusis formations, Nama Group, of southern Africa. A literature survey confirms a previously noted concentration of scratch circles reported from shallow marine upper Ediacaran–lower Cambrian and paralic Carboniferous rocks. Scratch circle identification and nomenclature are discussed. The stratigraphical range of the trace fossils Treptichnus pedum and Gyrolithes isp. in the Stáhpogieddi Formation are extended downward. Combined with earlier reports of Harlaniella podolica this adds new precision to the placement of the Ediacaran–Cambrianboundary on the Digermulen Peninsula.