Mesozoic strata of Kong Karls Land, Svalbard, Norway; a link to the northern Barents Sea basins and platforms

Abstract

Kong Karls Land, easternmost in the Svalbard archipelago, displays a 300 m-thick Upper Triassic (Norian) to Lower Cretaceous (Aptian) succession. The islands are situated within a set of large-scale, NE–SW-trending folds. The sediments are poorly consolidated as a result of relatively shallow burial. Lower Cretaceous plateau lavas and sills cap the islands and have protected older strata from extensive Pliocene and Pleistocene erosion. Correlation between onland exposures and subsea seismic units shows that Kong Karls Land is a key reference area for the Late Triassic to Early Cretaceous development of the northern Barents Sea shelf, but also to the southwestern Barents Sea. The unique exposed succession can be correlated with nearby offshore data, enabling the recognition of key sequence stratigraphic surfaces which define major tectonic events. These enable subdivision of the succession into six tectonic megasequences (TMS 1 to TMS 6) of latest Permian to Early Cretaceous age. The TMS 1 is linked to denudation of the Uralian orogen and includes most of the northwestward prograding Triassic coastline in the northwestern Barents Sea and eastern part of Svalbard. The 200 m-thick estuarine to shoreface deposits of the Rhaetian to Pliensbachian TMS 2 in Kong Karls Land stands in contrast to the 5 to 20 m-thick condensed succession with numerous hiatuses in western Spitsbergen. This significant difference is suggested to be a response to an evolving foreland basin linked to the northern Barents Sea Basin and Novaya Zemlya Fold and Thrust Belt. The four youngest tectonic megasequences are represented by only thin remnants onshore and on the adjacent platform. Outcrop mapping and seismic profiles show high-amplitude weak folding in the Late Jurassic followed by Early Cretaceous reactivation, prior to deposition of the Helvetiafjellet Formation. The volcanism in Kong Karls Land is related to the High Arctic Large Igneous Province and opening of the Amerasian Basin, which resulted in uplift of the northern Barents Shelf and southwards tilting of the Svalbard Platform..