Early Permian Stratigraphy and Sedimentology, NW Devon and SW Ellesmere Islands, Sverdrup Basin (Arctic Canada, Nunavut)

This study investigates the Upper Pennsylvanian (Gzhelian) to Lower Permian (Asselian– Artinskian) succession on NW Devon Island (Grinnell Peninsula) and SW Ellesmere Island (Bjorne Peninsula) along the southern margin of the Sverdrup Basin. Integrated facies and stratigraphic analyses delineate four third-order stratigraphic sequences of Gzhelian, early to middle Asselian, late Asselian–late Sakmarian, and latest Sakmarian–late Artinskian age. These record a complex interplay of sedimentation and episodic tectonic activity, with differential uplift and subsidence influencing facies distribution and thickness. Warm water, photozoan assemblages existed in the Gzhelian, but were overwhelmed by significant clastic influxes that diminished into the Early Permian. Gzhelian-aged deposits on Grinnell Peninsula are notably thin, a feather edge of considerably thicker deposits elsewhere in the basin. Glacio-eustatic cyclothems within the Asselian Belcher Channel Formation led to strata with characteristic resistant- recessive bands within a prolific photozoan carbonate factory, most notably Palaeoaplysina buildups. This high carbonate productivity ceased in the latest Asselian, primarily driven by the closure of the Uralian seaway which triggered a transition from warm photozoan to cool heterozoan carbonate factories into the Sakmarian. A narrow band of heterozoan-extended carbonates developed at the periphery of the basin indicating warm seawater temperatures were maintained in the shallowest of waters, that rapidly transition to heterozoan mudrock deposits within the rapidly subsiding area around Bjorne Peninsula. By the Artinskian, carbonate production was exclusively heterozoan, reflecting cooler oceanic conditions across the Sverdrup Basin.