Cenozoic structural evolution on northern Banks Island, N.W.T. 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 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.

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

Westgate

Bray

2021

Can. J. Earth Sci.

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Paralava and clinker from the Canadian Arctic: a record of combustion metamorphism dating back to the late Miocene

et al. 2023

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Outcrops with conspicuous reddish to yellow-colored clinker, blackish paralava, and blends of both with a breccia-like appearance occur across the Canadian Arctic. We examined such rocks on Ellesmere Island, Banks Island, and the Mackenzie Delta area. These rocks are a product from natural combustion of bituminous shale and low-rank coal seams in Cretaceous and Paleogene host sedimentary rocks, respectively. The main mineral phases of clinker and silicate paralava samples are comprised of quartz + hematite ± feldspars ± cristobalite (or tridymite) ± cordierite–sekaninaite ± clinopyroxene ± sillimanite ± glass. Slag-like iron-oxide paralava (74–95 wt.% total Fe2O3) consisting of hematite ± magnetite ± clinopyroxene occur in Paleogene host sedimentary rocks rich in siderite concretions. The whole-rock geochemical composition of clinker and silicate paralava shows similarities for samples from the same outcrop. Regional and local specific elemental enrichments are mainly inherited from the sedimentary protoliths, which are characterized by volcanogenic input (Paleocene sedimentary rocks) or oxygen depleted depositional conditions (Upper Cretaceous bituminous sedimentary rocks). Spontaneous combustion could take place when the organic-rich sedimentary rocks become exposed to atmospheric oxygen. This process has occurred at least since the Messinian stage (Miocene) on Ellesmere Island (6.1 ± 0.2 Ma; 40Ar39Ar incremental heating dating on whole-rock paralava) and continues until now. An active combustion process on scree from a coal seam and clastic Eureka Sound Group sedimentary rocks was observed on Ellesmere Island.

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The Devonian clastic wedge and underlying strata of southwestern Canadian Arctic Archipelago: stratigraphic revisions

Kabanov,

Dewing,

Atkinson

et al. 2024

Can. J. Earth Sci.

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The Devonian clastic wedge (DCW) and underlying carbonate platforms and basinal mudrocks of the study area are re-examined using legacy seismic data and XRF surveys of borehole chip samples. The Ordovician-Devonian basinal succession of Melville Island is consolidated under the name Ibbett Bay Group within the Northwest Territories, whereas equivalent strata in Nunavut are grouped into the Cape Phillips Formation. The Kitson Formation black shale is correlative with the upper Ibbett Bay Group. Six horizons with high TOC and high gamma response are traced in the Ordovician-Devonian, with the fourth (4a) approximating the Silurian/Devonian boundary; the upper two (4b, 5) are Emsian and Eifelian. In the direction of progradation, the base of Kitson Formation rises stratigraphically from gamma horizon 4a to 5. The upper Kitson represents basinal toes of westward prograding DCW clinoforms. The Blackley and Cape de Bray formations of Embry and Klovan (1976) are not traceable enough to warrant their formation rank. We revert to the original usage of Tozer and Thorsteinsson (1964) where these units are members within the Weatherall Formation. The distinctive seismic character of the Cape de Bray in western and central Melville Island warrants its recognition as a formal member; elsewhere it is informal as it cannot be consistently traced. The Blackey is treated as a formal member in an outcrop area of ⁓2000 km2 where it was defined; it is not recognized in the subsurface. Onset of the DCW is tentatively linked to flexural subsidence and crustal thickening caused by the Romanzof Orogeny in the hinterland.

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Cenozoic structural evolution on northern Banks Island, N.W.T. Canada

Cited by 3 publications

References 28 publications

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

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

Paralava and clinker from the Canadian Arctic: a record of combustion metamorphism dating back to the late Miocene

The Devonian clastic wedge and underlying strata of southwestern Canadian Arctic Archipelago: stratigraphic revisions

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