Late Triassic (early Carnian–Norian) palynology of the Sentralbanken High, Norwegian Barents Sea

Abstract

ABSTRACTFour stratigraphic cores (7533/2-U-1, 2-U-2, 3-U-7 and 7534/4-U-1) drilled in the Sentralbanken High provide important reference sections for the Upper Triassic succession in the northern Barents Sea. The cores span the De Geerdalen, Flatsalen and Svenskøya formations (Kapp Toscana Group), which are equivalent to the Snadd to middle Fruholmen formations of the southern Barents Sea. Only cursory palynological study of the cores has been conducted previously, and no published palynofacies data is available. We present a detailed palynostratigraphy from the cores, and describe six informal palynological assemblages. Comparison with independently dated sections from elsewhere in the region enables a revised age interpretation of early Carnian to Norian for the cored interval, thereby improving correlation between Sentralbanken, Svalbard and the southern Barents Sea. A dominance of amorphous organic matter (AOM) and marine palynomorphs indicates a distal suboxic–anoxic marine depositional environment for the lower De Geerdalen Formation, with an abrupt change to a nearshore marine environment above an erosion surface in core 7534/4-U-1. Palynofacies from the remainder of the formation are characterised by a dominance of phytoclasts and are interpreted as indicative of a delta front to coastal plain environment. The reappearance of AOM, microforaminiferal test linings and marine microphytoplankton in the Flatsalen Formation in cores 7533/2-U-1 and 2-U-2 reflects a regional transgression of early Norian age. Reworked palynomorphs, shale rip-up clasts and a transition to phytoclast-dominated palynofacies above an erosion surface at the base of the overlying Svenskøya Formation is consistent with a disconformity, which was previously identified as a possible sequence boundary on the neighbouring island of Hopen.