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TitleExposed evaporite diapirs and minibasins above a canopy in central Sverdrup Basin, Axel Heiberg Island, Arctic Canada
AuthorHarrison, J C; Jackson, M P A
SourceBasin Research vol. 26, 2014 p. 567-596,
Alt SeriesEarth Sciences Sector, Contribution Series 20130142
Mediapaper; on-line; digital
File formatpdf
ProvinceNunavut; Northwest Territories
NTS49C/12; 49C/13; 49C/14; 49F/03; 49F/04; 49F/05; 49F/06; 49F/11; 49F/12; 49F/13; 49F/14; 49G; 49H/12; 49H/13; 59; 69; 79; 89A/01; 89A/02; 89A/15; 89D/08; 89D/09; 89D/10; 89D/15; 89D/16; 89E/07; 89E/08; 340B; 340C; 340D/04; 340D/05; 340D/11; 340D/12; 340D/13; 340D/14; 560A; 560B/01; 560B/08; 560D
AreaSverdrup Islands; Axel Heiberg Island
Lat/Long WENS-114.0000 -79.0000 82.0000 76.0000
Subjectstectonics; structural geology; basins; basin analyses; evaporites; tectonostratigraphic zones; stratigraphic analyses; basin evolution; Cenozoic
Illustrationslocation maps; cross-sections; photographs
ProgramGEM: Geo-mapping for Energy and Minerals GEM Tri-Territorial Information Management & databases (Tri-Territorial Bedrock Framework)
Released2014 03 05
AbstractAxel Heiberg Island (Arctic Archipelago, northern Nunavut, Canada) contains the thickest Mesozoic section in Sverdrup Basin (11 km). The ca. 370-km-long island is second only to Iran in its concentration of exposed evaporite diapirs. Forty-six diapirs of Carboniferous evaporites and associated minibasins are excellently exposed on the island. Regional anticlines, which formed during Paleogene Eurekan orogeny, trend roughly north on a regular ca. 20-km wavelength and probably detach on autochthonous Carboniferous Otto Fiord Formation evaporites comprising halite overlain by thick anhydrite. In contrast, a 60-km-wide area, known as the wall-and-basin structure (WABS) province, has bimodal fold trends and irregular (<10 km) wavelengths. Here, crooked, narrow diapirs of superficially gypsified anhydrite crop out in tight anticline cores, which are separated by wider synclinal minibasins. We interpret the WABS province to detach on a shallow, partly exposed canopy of coalesced allochthonous evaporite sheets. Surrounding strata record a salt-tectonic history spanning the Late Triassic (Norian) to the Paleogene. Stratigraphic thinning against diapirs and spectacular angular unconformities indicate mild regional shortening in which diapiric roof strata were bulged up and flanking strata steepened. This bulging culminated in the Hauterivian, when diapiric evaporites broke out and coalesced to form a canopy. As the inferred canopy was buried, it yielded second-generation diapirs, which rose between minibasins subsiding into the canopy. Consistent high level emplacement suggests that all exposed diapirs inside the WABS area rose from the canopy. In contrast, diapirs along the WABS margins were sourced in autochthonous salt as firstgeneration diapirs. Apart from the large diapir-flanking unconformities, Jurassic-Cretaceous depositional evidence of salt tectonics also includes submarine debris flows and boulder conglomerates shed from at least three emergent diapirs. Extreme local relief, tectonic slide blocks, steep talus fans and subaerial debris flows suggest that many WABS diapirs continue to rise today. The Axel Heiberg canopy is one of only three known exposed evaporite canopies, each inferred or known at a different structural level: above the canopy (Axel Heiberg), through the canopy (Great Kavir) and beneath a possible canopy (Sivas).
Summary(Plain Language Summary, not published)
Axel Heiberg Island in northern Nunavut is the site of numerous geological features that contain rock salt in the subsurface and allied rocks that are exposed to viewing. Such rocks are often associated with liquid and gaseous hydrocarbons elsewhere in the Arctic although this has not been proven on Axel Heiberg Island. Nevertheless conditions suitable for the entrapment of gas and oil may exist. Studies described in this paper illuminate the many varied ways in which the salt structures of Axel Heiberg Island have been emplaced over the last 230 million years: as pillars, sheets and tear dropped shaped bodies. Field work also indicates that numerous small basins have formed in the surrounding sedimentary rocks and that the rock salt continues to flow and modify the landscape.

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