Foraminiferal stratigraphy and palaeoenvironment of a storm-influenced marine shelf: Upper Aptian – lower Albian, Svalbard, Arctic Norway

Abstract

This study presents the first record of foraminifera from the Lower Cretaceous Carolinefjellet Formation on the Svalbard archipelago, Arctic Norway. The Svalbard foraminiferal assemblages are dominated by agglutinated forms with a subordinate calcareous component. Several stratigraphically important species are recognised, and four assemblage zones are established: 1) Serovaina loetterlei Zone of middle Aptian or lower, 2) Ammobaculites wenonahae Zone of the middle Aptian, 3) Gaudryina tailleuri Zone of the upper Aptian, 4) Verneuilinoides borealis Zone of the lower Albian. The assemblages exhibit characteristic Boreal features, previously reported from the North Slope of Alaska, Arctic Canada, Western Siberia, and older Mesozoic strata in Svalbard. The study therefore allows for Circum-Arctic correlations and the extensions of stratigraphic ranges of several Boreal species.The investigated succession exhibits a large-scale fining-upwards trend. The lower part (the Dalkjegla Member) is characterised by abundant hummocky cross-stratified and wave-ripple cross-laminated sandstone beds, indicating deposition on a storm-dominated shelf. The upper part (the Innkjegla Member) is dominated by mudstones containing strata-bound siderite concretions and carbonate-cemented sandstone beds, suggesting deposition under more quiescent, middle to outer shelf conditions. An upwards increase in trace fossil diversity and degree of bioturbation, in concert with expanding foraminiferal diversity and morphogroup variability, reflects a long-term deepening of the shelf with fluctuating oxygen conditions. In combination with XRF data, diversity statistics, and morphogroup application, the present study thus sheds a new light on higher frequency palaeoenvironmental changes in upper part of the Carolinefjellet Formation.