An Arenig graptolite from Bell Island, eastern Newfoundland - its biostratigraphic and paleogeographic significance

Abstract

An interval of dark grey silts and shales within the Youngsters Gulch Member of the Powers Steps Formation (basal Wabana Group) on Bell Island, eastern Newfoundland yields a monospecific graptolite assemblage consisting of Didymograptus (sensu lato) simulans Elles and Wood. This species has hitherto been recorded only from Great Britain and Bohemia, with possible specimens from China, thus lending support to the currently accepted paleogeographic reconstruction of Newfoundland in the Ordovician. The occurrence of D. (s.l) simulans permits accurate biostratigraphic correlation of the Powers Steps Formation with equivalent North American and European sequences. The formation is of early/middle Arenig age, equivalent to Bed 11 of the Cow Head Group of western Newfoundland, to part of the D. deflexus or D. nitidus zones of northern England and to the lower part of the Arenig Series of Arennig Fawr, North Wales. -Author