High latitude stratigraphical palynology of the Jurassic–Cretaceous boundary interval, Sverdrup Basin, Arctic Canada

The Rollrock Section on northern Ellesmere Island (Arctic Canada) exposes a continuous succession of Upper Jurassic to Lower Cretaceous strata, of which 537 m were logged and sampled at 1.5 m intervals for palynological analysis. Consequently, these strata form one of the most comprehensive archives of Arctic biostratigraphy of the Jurassic–Cretaceous boundary interval. As such, their occurrence is valuable to our understanding of high latitude climate change and floral turnover over this poorly defined boundary. Previous macrofossil studies indicate a shallow, distal depositional environment for the succession. Palynomorph assemblages from the Rollrock Section display a sequence of palynostratigraphic events stretching from the Oxfordian to the early Valanginian. The dinocyst taxa reported in this study enable the division of the section into seven distinct biozones, as defined by first occurrences of Paragonyaulacysta capillosa, Prolixosphaeridiopsis spissa, Trichodinium erinaceoides, Oligosphaeridium complex, and Muderongia simplex, and the last occurrences of Gonyaulacysta jurassica adecta and Rhynchodiniopsis cladophora. The palynostratigraphic events displayed have enabled modifications to existing biostratigraphic schemes. Provincialism and the lack of a defined Jurassic–Cretaceous boundary complicate attempts at global correlation. The base of the Valanginian marks the first palynological event in the Cretaceous, which can be correlated across the Boreal Realm, with potential correlation to biological events in the Tethyan Realm.