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

Abstract

New information on acritarchs from the Duolbagáisá Formation, Digermulen Peninsula, Arctic Norway, enable recognition of the three Cambrian Series 2 acritarch-based zones: the <i>Skiagia ornata–Fimbriaglomerella membranacea, Heliosphaeridium dissimilare–Skiagia ciliosa and Volkovia dentifera–Liepaina plana</i> Assemblage zones. Acritarchs of the <i>Skiagia ornata–Fimbriaglomerella membranacea</i> Zone (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 with <i>Kjerulfia</i> n. sp. and <i>Elliptocephala</i> n. sp., appears an assemblage with abundant <i>Skiagia ciliosa</i>, indicative of the <i>Heliosphaeridium dissimilare–Skiagia ciliosa</i> Zone. A few metres higher appear <i>Liepaina plana, Heliosphaeridium notatum</i> and <i>Retisphaeridium dichamerum</i>, which indicate the <i>Volkovia dentifera–Liepaina plana</i> Zone (Cambrian Stage 4). The transition between the Duolbagáisá Formation and the overlying Kistedalen Formation is marked by the appearance of <i>Comasphaeridium longispinosum, Multiplicisphaeridium llynense</i> and <i>Eliasum llaniscum</i>, diagnostic of the Miaolingian Series. This coincides with the disappearance of <i>Skiagia</i>; occurrences of <i>Skiagia</i> in Miaolingian strata consist of reworked material related to the Hawke Bay regression at the Cambrian Stage 4–Wuliuan transition. The absence of <i>Skiagia</i> in 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 the <i>Skiagia ornata–Fimbriaglomerella membranacea, Heliosphaeridium dissimilare–Skiagia ciliosa</i> and <i>Volkovia dentifera–Liepaina plana</i> zones 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.