Lower Cretaceous holostratigraphy in Svalbard: the Arctic key piece of the Boreal basin puzzle

Abstract

Lower Cretaceous stratigraphy of the high palaeo-latitude Arctic-Boreal Realm is generally more poorly understood than its lower-latitude Tethyan counterpart, prohibiting regional correlations and evaluation of global climate dynamics during this important high-pCO2 period. In this paper, a holostratigraphic scheme and lithostratigraphic revision are presented for the Valanginian–lower Barremian, siliciclastic ramp succession of the Rurikfjellet Formation in Svalbard, drawn from synthesis of the latest published sedimentological, biostratigraphic, petrophysical, sequence stratigraphic, chemostratigraphic and chronostratigraphic results, supplemented by new measured sections from five localities. The offshore mudstone-dominated Wimanfjellet Member (Valanginian–lower Barremian) is retained, whereas three new members are defined according to their distinct geographical, sedimentological and stratigraphic characteristics. The Adventpynten Member (upper(?) Valanginian–lowermost upper Hauterivian) constitutes a thick, relatively localized succession of mass-transport deposits. The Kikutodden Member (Hauterivian–lower Barremian) is discarded and replaced by the northern Bohemanneset Member and southern Fotografryggen Member, representing respectively: heterogeneous prodelta to delta front deposits; and sandy offshore transition to shoreface deposits. The Rurikfjellet Formation records Valanginian–earliest late Hauterivian shoreline progradation followed by late Hauterivian–early Barremian shoreline retreat and flooding across a low-gradient ramp, which never experienced full regression into continental deposits within the extent of the present-day outcrop belt.