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TitreExposed evaporite diapirs and minibasins above a canopy in the central Sverdrup Basin, Axel Heiberg Island, Arctic Canada
AuteurHarrison, J C; Jackson, M P A
SourceBasin Research vol. 26, 2014 p. 567-596, https://doi.org/10.1111/bre.12037
Année2014
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130142
ÉditeurBlackwell Publishing Limited
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1111/bre.12037
Mediapapier; en ligne; numérique
Formatspdf
ProvinceNunavut; Territoires du Nord-Ouest
SNRC49C/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
Lat/Long OENS-114.0000 -79.0000 82.0000 76.0000
Sujetsbassins; analyses du bassin; évaporites; zones tectonostratigraphiques; analyses stratigraphiques; evolution du bassin; tectonique; géologie structurale; Cénozoïque
Illustrationslocation maps; cross-sections; photographs
ProgrammeBases de données couvrant les trois territoires (Géologie du substratum rocheux), GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
Axel 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).
Résumé(Résumé en langage clair et simple, non publié)
L'île Axel-Heiberg dans le nord du Nunavut contient de nombreuses entités géologiques qui renferment du sel gemme en subsurface et des roches connexes facilement visibles. Ailleurs dans l'Arctique, ces roches indiquent souvent la présence d'hydrocarbures sous formes de liquide et de gaz, mais rien n¿indique que ce soit aussi le cas sur l'île Axel Heiberg. Les conditions pourraient cependant convenir au piégeage de gaz et de pétrole. Les études décrites dans ce document font la lumière sur les nombreuses façons dont les structures de sel de l'île Axel Heiberg se sont mises en place depuis 230 millions d'années, notamment sous forme de piliers, de manteaux et de goutte d'eau. Les travaux accomplis sur le terrain indiquent aussi que de nombreux petits bassins se sont formés dans la roche sédimentaire environnante et que le sel gemme continue de se déplacer et de façonner le paysage.
GEOSCAN ID292788