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 Para-gonyaulacysta 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 biostrati-graphic schemes. Provincialism and the lack of a defined Jurassic-Cretaceous boundary complicate at-tempts 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. (c) 2021 Elsevier Ltd. All rights reserved.
Bibliographical noteAcknowledgements: The authors would like to thank the following people and institutions for their valuable support: Sylvie LeBlanc (Department of Culture and Heritage, Iglooik, Canada); Jane Chisholm and rangers of Parks Canada (Iqaluit and Tanquary Camp, Canada); John Innis (Universal Helicopters); the staff of Polar Continental Shelf Programme at Resolute Bay (Canada). Fellow geologists Berta Lopez-Mir and Peter Hülse (both CASP, Cambridge, UK) participated in fieldwork in 2015. The help of field assistant Alex Chavanne (California, USA) with logging and sampling the Rollrock Section was instrumental. Ashton F. Embry (Geological Survey of Canada, Calgary) kindly shared unpublished information. Dave Bodman of MB Stratigraphy Ltd. (Sheffield, UK) prepared part of the palynological slides used in this study. CASP's industry sponsors are acknowledged for their funding of the Canadian Arctic Islands Project. The authors would also like to thank reviewers Kasia K. Śliwińska (Geological Survey of Denmark and Greenland, Copenhagen, Denmark) and Jennifer Galloway (Carleton University, Ottawa, Canada) for their constructive criticism of this paper and editor-in-chief Eduardo Koutsoukos (University of Heidelberg, Germany) for his careful editing.
- Boreal Realm
- Oppel zones