LATE TRIASSIC (CARNIAN-NORIAN) PALYNOLOGY OF THE DE GEERDALEN FORMATION, SENTRALBANKEN HIGH, BARENTS SEA

During the Late Triassic, a vast delta-complex infilled an enclosed seaway on the northern shores of Pangaea, in the area of the modern-day Barents Sea. These paralic deposits are widespread in the subsurface of the Barents Shelf, subcropping under a thin cover of Quaternary till, and are well exposed on the islands of the adjacent Svalbard Archipelago. The precise dating of the succession is difficult due to the scarcity of age-diagnostic macrofossils; however, palynology has proved to be a useful dating method. The results of a quantitative palynological study of a stratigraphic core, drilled in the Sentralbanken High in the northern Barents Sea, contribute important new data concerning the dating and correlation of the succession. Core 7533/2-U-1 spans a 198.3 m interval of shale, sandstone and coal, and is assigned to the De Geerdalen Formation. Seventy-three samples were analysed, yielding well-preserved and taxonomical diverse palynofloras. The palynological succession is subdivisible into three units, correlatable to assemblages from the De Geerdalen Formation on the island Hopen, approximately 300 km to the northwest. Samples from the lower part of the core (198.20 – 47 m) were characterised by a dominance of the fern spore Leschikisporis aduncus and are identical to assemblages from the lower exposures of the De Geerdalen Formation on Hopen. A transition to assemblages rich in the gymnosperm pollen Protodiploxypinus spp. was noted between 36 and 24 m, and is closely comparable to assemblages from the upper De Geerdalen Formation (Hopen Member). The abundance of Kyrtomisporis spp. above 24 m, combined with the first appearance of several taxa including Cavatoretisporites obvius, Limbosporites lundbladii and Retitriletes austroclavatidites, is consistent with assemblages described from the transition between the De Geerdalen and Flatsalen formations on Hopen. Independent age constraints on Hopen suggests a late Carnian – early Norian for the core. The relatively low abundance of marine indicators throughout core 7533/2-U-1 suggests that the Sentralbanken area occupied a more proximal palaeogeographic setting than Hopen during the late Carnian.