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 the potential for reliable, precise correlation of Upper Cretaceous sedimentary rocks across the three major depo...
| Main Authors: | , |
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
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University of Toronto
2021
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| Online Access: | http://hdl.handle.net/1807/107755 http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2021-0031 |
| Summary: | 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 the potential for reliable, precise correlation of Upper Cretaceous sedimentary rocks across the three major depocentres of the Arctic Archipelago and adjacent northern continental margin: Sverdrup, Banks, and the Beaufort-MacKenzie basins. Twenty-one tephra beds were analyzed; all have a high-K, peraluminous, rhyolitic composition with quartz, plagioclase, ilmenite, biotite, and zircon as the dominant minerals. Trace-element concentrations, especially low Nb and Ta, show that the parental magmas formed in a continental-margin subduction environment. Glass fission-track ages range from 100 Ma to younger than 60 Ma and indicate a very low sedimentation rate giving a very condensed sedimentary sequence in SW Banks Island – a sequence that may well contain the K-Pg transition. Source calderas are unknown but most likely are situated in east-central Alaska and the central and northern Kuskokwim volcanic belt, some 1000 to 1500 km distant from SW Banks Island. It is also possible that some of the very thin tephra beds come from the Okhotsk-Chukotka volcanogenic belt in NE Russia. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author. |
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