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Sedimentology and tectonic history of the Eureka Sound and Beaufort formations, southern Ellesmere Island, Arctic, Canada

University of British Columbia

The Eureka Sound Formation in the eastern Canadian Arctic Archipelago is an Upper Cretaceous to Paleogene pre- and syn-tectonic deposit that records the uplift and segmentation of the Early Carboniferous to Tertiary Sverdrup Basin. Scattered outliers of the Eureka Sound Formation on southern Ellesmere Island rest unconformably on or are faulted against Devonian strata. In the vicinity of Vendom, Stenkul, Baumann and Sor Fiords, the Eureka Sound Formation attains a maximum thickness of 480 m and comprises a sequence of nonmarine and brackish water deposits that ranges in age from mid-Paleocene to Late Eocene. Eureka Sound strata which crop out along the shores of Stenkul Fiord are divided into four lithofacies assemblages. The stratigraphic section is composed mainly of two nonmarine assemblages which alternate throughout the sequence. Lithofacies Assemblage I consists of fining-upward sandstones which attain thicknesses of 20 m and are interpreted as fluvial deposits. Lithofacies Assemblage II comprises interbedded mudstones and coal in seams up to 8 m thick, and are interpreted as floodbasin deposits of an alluvial plain. Two marine lithofacies assemblages (III, IV) are recognized locally and constitute a minor part of the stratigraphic succession. Lithofacies Assemblage III comprises the basal strata in the study area and consists of approximately 90 m of buff-weathering mudstones and interbedded thin coals which were deposit ed in brackish lagoonal, estuarine and salt marsh environments. Lithofacies Assemblage IV occurs locally in the middle of the stratigraphic section and consists of up to 10m of white, well sorted quartz arenites and minor mudstones, which are interpreted as deposits of a barrier island system. To the northeast of Stenkul Fiord at Makinson Inlet, outliers of the Eureka Sound Formation rest unconformably on Paleozoic strata, and are in turn overlain with angular unconformity by as much as 120 m of Early Miocene fanglomerates of the Beaufort Formation. The ages of these sediments, in conjunction with ages reported from the Eureka Sound and Beaufort Formations in other parts of Ellesmere and Axel Heiberg Islands, bracket the timing of the orogenic phase of the Eurekan orogeny in the eastern Arctic as Late Eocene to Miocene.

Text

2010-05-22

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http://hdl.handle.net/2429/24904

Geological Sciences

University of British Columbia

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