Helvetiafjellet formation (Barremian-Aptian), Spitsbergen: Characteristics of a transgressive succession

Abstract

Helvetiafjellet Formation (Barremian-Aptian) is one of the most prominent Mesozoic sandstone intervals on Svalbard. It consists of fluvial distributary, delta-plain, mouth-bar, barrier-bar, tidal estuary and transgressive sheet sandstone fades associations, arranged in a large-scale, transgressive stacking pattern. The formation unconformably overlies shelf mudstones in the northwesterly areas, but grades conformably upwards from a delta-front succession in the southeast. Layer-cake, simple progradational and transgressive onlapping depositional models for the succession are reviewed and discussed. A new stratigraphic model, involving a long-term (5-12 m.y.) fall and rise of relative sea level is proposed, consistent with the varying nature of the basal bounding surface, with the complex internal distribution of marine and non-marine facies associations and with the overall transgressive nature of the succession. Higher-frequency sequences can also be distinguished within the formation. © 1995, Elsevier B.V.