Dinocyst stratigraphy of the Valanginian–Aptian Rurikfjellet and Helvetiafjellet formations on Spitsbergen, Arctic Norway

Abstract

In order to improve the understanding of how the high northern latitudes responded to the escalating warming which led to the middle Cretaceous super greenhouse climate, more temperature proxy records from the High Arctic are needed. One of the current obstacles in obtaining such records is poor age control on the Lower Cretaceous strata in the Boreal region. Here, we provide a biostratigraphic framework for the Rurikfjellet and Helvetiafjellet formations representing the lower part of the Lower Cretaceous succession on Spitsbergen. We also attempt to date the boundary between the Agardhfjellet and the Rurikfjellet formations. This study is based on dinoflagellate cysts (dinocysts) from three onshore cores (DH1, DH2 and DH5R) and three outcrop sections (Bohemanflya, Myklegardfjellet and Ullaberget). Relatively abundant and well-preserved dinocyst assemblages from the Rurikfjellet Formation date this unit as early Valanginian – early Barremian. The dinocyst assemblages from the Helvetiafjellet Formation are significantly impoverished and are characterized by reworking, but collectively indicate a Barremian–Aptian age for this formation.

The role of shelf morphology on storm‐bed variability and stratigraphic architecture, Lower Cretaceous, Svalbard

“…Śliwińska et al. (2020) presented an updated biostratigraphic framework for the lower wedge and the overlying paralics. Jelby et al.…”

“…The lower wedge is assigned to the Valanginianlower Barremian Rurikfjellet Formation, which consists of the shale-dominated Wimanfjellet Member and the overlying sandstone-rich Kikutodden Member (Figs 2D, 3C, 5A, 6A and 6B;Dypvik et al, 1991b;Grundv ag et al, , 2019Jelby et al, 2020;Sliwi nska et al, 2020). The two units form a 200 to 300 m thick coarsening-upward succession, with only the sandstone beds of the Kikutodden Member displaying basinward thinning (to the south-east; Fig.…”

“…, 2020; Śliwińska et al. , 2020). The two units form a 200 to 300 m thick coarsening‐upward succession, with only the sandstone beds of the Kikutodden Member displaying basinward thinning (to the south‐east; Fig.…”

“…The investigated siliciclastic sediment wedges were mainly chosen on the basis of their wellknown biostratigraphic and lithostratigraphic framework and their excellent exposures (for example, Figs 2D, 3 and 5; Nagy, 1970;Dypvik et al, 1991a;Hurum et al, 2016;Sliwi nska et al, 2020;Jelby et al, 2020). In addition, the Early Cretaceous tectonic and palaeogeographic evolution of the shelf on which the wedges accumulated, is well-constrained (Fig.…”

Tempestite facies variability and storm‐depositional processes across a wide ramp: Towards a polygenetic model for hummocky cross‐stratification

“…). However, considering the thickness ( ca 106 m) of the shale‐dominated and age‐equivalent (Śliwińska et al ., in press) Wimanfjellet Member in the distal locality of Baronfjella (Table ; Fig. B and D), hyperpycnal fluid‐mud deposits may constitute parts of the succession (Table ; Fig.…”