Sequence stratigraphy and microplankton palaeoenvironmental dynamics across the Jurassic–Cretaceous transition in the Canadian Arctic

ABSTRACT The Jurassic to Cretaceous strata exposed in the Rollrock Section, Sverdrup Basin, Arctic Canada, represent one of northernmost continuous outcrops spanning this poorly understood transition. Oxfordian–Valanginian mudstones Section were deposited a shallow marine environment and, as such, provide ideal lithology investigate response high latitude dinoflagellate cyst populations frequent environmental perturbations time. Using multivariate statistical approach, distinct palaeoecologically significant groups are identified and directly linked time palaeoenvironments, allowing for reconstruction underlying long term palaeoenvironmental trends. These trends be driven by sequence stratigraphic cycles. For first time, fourth order sequences recorded from pivotal period Basin reveal an additional level short climatic events that complicate identification relationship existing between phytoplankton climate is utilised decipher interplay long-term short-term fluctuations, distinguishing them evolutionary Two cysts, process morphology, act proxies. High percentages proximochorate such Trichodinium erinaceoides , indicate more proximal, energy, nutrient rich conditions dominant transgressive systems tracts. chorate Oligosphaeridium complex signify distal, low depleted highstand