Acritarchs from the Duolbagáisá Formation (Cambrian Series 2, Miaolingian) on the Digermulen Peninsula, Finnmark, Arctic Norway: towards a high-resolution Cambrian chronostratigraphy

Abstract

AbstractNew information on acritarchs from the Duolbagáisá Formation, Digermulen Peninsula, Arctic Norway, enable recognition of the three Cambrian Series 2 acritarch-based zones: theSkiagia ornata–Fimbriaglomerella membranacea,Heliosphaeridium dissimilare–Skiagia ciliosaandVolkovia dentifera–Liepaina planaAssemblagezones. Acritarchs of theSkiagia ornata–Fimbriaglomerella membranaceaZone (Cambrian Stage 3) appear near the base of the unit, close to an undetermined trilobite. In the Upper Member of the Duolbagáisá Formation, in levels withKjerulfian. sp. andElliptocephalan. sp., appears an assemblage with abundantSkiagia ciliosa, indicative of theHeliosphaeridium dissimilare–Skiagia ciliosaZone. A few metres higher appearLiepaina plana,Heliosphaeridium notatumandRetisphaeridium dichamerum, which indicate theVolkovia dentifera–Liepaina planaZone (Cambrian Stage 4). The transition between the Duolbagáisá Formation and the overlying Kistedalen Formation is marked by the appearance ofComasphaeridium longispinosum,Multiplicisphaeridium llynenseandEliasum llaniscum, diagnostic of the Miaolingian Series. This coincides with the disappearance ofSkiagia; occurrences ofSkiagiain Miaolingian strata consist of reworked material related to the Hawke Bay regression at the Cambrian Stage 4–Wuliuan transition. The absence ofSkiagiain higher levels of the Duolbagáisá Formation and Kistedalen Formation suggests that no unconformity formed during the Hawke Bay regression in this area. The chronostratigraphical significance of theSkiagia ornata–Fimbriaglomerella membranacea,Heliosphaeridium dissimilare–Skiagia ciliosaandVolkovia dentifera–Liepaina planazones is critically analysed. Correlation of the Duolbagáisá Formation with peri-Gondwanan terrains of Avalonia and Iberia is established. The Digermulen Peninsula has great potential as a reference section for establishing a Cambrian chronostratigraphy based on acritarchs.