Late Triassic (Carnian– Rhaetian) palynology of Hopen, Svalbard

Abstract

Triassic strata crop out extensively on the Svalbard Archipelago and subcrop under much of the Barents Sea. However, due to the remoteness of the region, relatively few palynostratigraphic studies of the Upper Triassic succession have been conducted. Consequently, existing palynological zonations for the Late Triassic in the region are of relatively low temporal resolution. In this study, 154 palynological samples from eight outcrop localities on the island of Hopen, Svalbard Archipelago, were analysed. Hopen offers unique insights into the subsea geology of the Barents Sea due to its position as the most southeasterly island of the archipelago. Samples spanning the De Geerdalen, Flatsalen and Svenskøya formations (Kapp Toscana Group) yielded well preserved palynofloras. The dense vertical and lateral distribution of samples makes this the most detailed palynological investigation of LateTriassic strata conducted thus far in the region. Six palynological assemblages were recognised using relative abundance and first stratigraphic appearance data; in ascending stratigraphic order these are the: (1)Leschikisporis aduncus assemblage (late Carnian), (2)Protodiploxypinus spp. assemblage (late Carnian– ? early Norian), (3)Classopollis torosus assemblage (early Norian), (4)Rhaetogonyaulax rhaetica assemblage (early Norian), (5)Limbosporites lundbladii– Quadraeculina anellaeformis assemblage (? late Norian–? Rhaetian) and the (6)Rogalskaisporites ambientis assemblage (? late Rhaetian). The palynological assemblages are compared to previous palynological studies on the island and to existing palynozonations for the region. A revised age interpretation for Hopen is provided based on the integration of palynology and independent chrono- and biostratigraphic evidence. The youngest strata are interpreted to be of Rhaetian age and yielded palynomorph assemblages remarkably similar to contemporaneous assemblages previously described from China, Australia and New Zealand. The study contributes important empirical data concerning the Late Triassic palynofloras along the northern shores of Pangaea.