Palaeogeographic reconstructions of the Russian Boreal areas and Svalbard during the Triassic

Abstract

Triassic palaeogeographic and palaeoclimatic environments of the Russian Arctic Boreal Province and Svalbard are reconstructed. Multi-facies complexes of clayey, silty and sandy deposits, with various biogenic nodules, accumulated throughout the Triassic, whereas phosphate accumulation was especially characteristic of the Middle Triassic. The entire region consisted of a series of shelf palaeobasins to the south of a wide, deep-water basin that we call the Northern Basin. This was connected to the Palaeo-Pacific. The climate of the region remained warm, with variable humidity, throughout the Triassic. The Franz Josef Land Archipelago stood out for its humid sedimentation during this period. Changes in the sedimentation regime caused by tectonic activity in parts of the territory took place around the Middle–Late Triassic transition. Sharp regression occurred in adjacent areas at the end of the Triassic because of the Atlantic Ocean opening. This provides an explanation for the absence of upper Norian and Rhaetian deposits in the Barents–Kara region. The general accumulation of sediments in the region only resumed in the Early Jurassic.