Glass fission-track ages, composition, and origin of tephra beds in the Upper Cretaceous Kanguk Formation, Banks Island, Arctic Canada

More than 50 conspicuous tephra beds occur in the Kanguk Formation of SW Banks Island. Their glass shards are remarkably well preserved and permit comprehensive characterization offering potential for reliable, precise correlation Upper Cretaceous sedimentary rocks across three major depocentres Arctic Archipelago adjacent northern continental margin: Sverdrup, Banks, Beaufort-MacKenzie basins. Twenty-one were analyzed; all have a high-K, peraluminous, rhyolitic composition with quartz, plagioclase, ilmenite, biotite, zircon as dominant minerals. Trace-element concentrations, especially low Nb Ta, show that parental magmas formed continental-margin subduction environment. Glass fission-track ages range from 100 Ma to younger 60 indicate very sedimentation rate giving condensed sequence Island – may contain K-Pg transition. Source calderas unknown but most likely situated east-central Alaska central Kuskokwim volcanic belt, some 1000 1500 km distant It is also possible thin come Okhotsk-Chukotka volcanogenic belt NE Russia.