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TitleEvidence for protracted High Arctic large igneous province magmatism in the central Sverdrup Basin from stratigraphy, geochronology, and paleodepths of saucer-shaped sills
AuthorEvenchick, C A; Davis, W J; Bédard, J H; Hayward, N; Friedman, R M
SourceGeological Society of America Bulletin 2015 p. 1-25,
Alt SeriesEarth Sciences Sector, Contribution Series 20140193
PublisherGeological Society of America
Mediaon-line; digital
File formatpdf
NTS69D/13; 69E/04; 69F; 69G/02; 69G/03; 69G/04; 69G/05; 79E/09; 79E/16; 79H/01; 79H/02; 79H/07; 79H/08
AreaSverdrup Basin; Ellef Ringnes Island
Lat/Long WENS-106.0000 -99.0000 79.5000 77.7500
Subjectsgeochronology; stratigraphy; stratigraphic analyses; systematic stratigraphy; sedimentary rocks; magmatism; igneous rocks; uranium lead dates; uranium lead dating; magmatic rocks; Sverdrup Basin; Beaufort Formation; Eureka Sound Group; Kanguk Formation; Hassel Formation; Christopher Formation; Isachsen Formation; Deer Bay Formation; Ringnes Formation; McConnell Formation; Jameson Bay Formation; King Christian Formation; Cenozoic; Tertiary; Mesozoic; Cretaceous; Jurassic; Paleozoic
Illustrationslocation maps; photographs; stratigraphic columns; plots; tables; Concordia diagrams
ProgramWestern Arctic, High Arctic LIP, GEM2: Geo-mapping for Energy and Minerals
AbstractField evidence, map compilation, geochemistry, geochronology, and potential field data document six intervals of Cretaceous magmatism in the central Sverdrup Basin. These are: (1) Hauterivian (ca. 130 Ma) volcaniclastic deposition in the lower Isachsen Formation; (2) 126.6 ± 1.2 Ma (U-Pb zircon) gabbroic intrusion; (3) 120.8 ± 0.8 Ma (U-Pb baddeleyite) diabasic intrusion; (4) 105.40 ± 0.22 Ma (U-Pb detrital zircon) pyroclastic deposition at the top of the Invincible Point Member, Christopher Formation; (5) upper Albian (ca. 103 Ma) pillow and hydroclastic breccia in the upper Christopher Formation; and (6) uppermost Albian (ca. 101 Ma) volcanic breccia and scoria in the Hassel Formation. Whole-rock geochemical data show that these magmatic rocks are similar to previously documented High Arctic large igneous province tholeiitic basalts, but analyses of fresh glass in tuffs reveal evolved ferroandesite to dacite compositions not recorded in whole-rock data. Approximate ages of saucer-shaped sills inferred from the relationship of sill width to depth of emplacement suggest at least three intervals of sill emplacement between 130 and 120 Ma. The new data show that volcanism in the Sverdrup Basin was of greater spatial extent, and that magmatism occurred more frequently, than was previously recognized. Comparison of the new central Sverdrup Basin data and interpretations with other data sets from the Sverdrup Basin, Svalbard, and Franz Josef Land suggests that High Arctic large igneous province magmatism occurred over a more extended period of time in the central Sverdrup Basin than in other regions.
Summary(Plain Language Summary, not published)
The evolution of the Arctic Ocean between the Canadian Arctic Islands, Alaska, Arctic Norway, and Siberia is uncertain because conventional methods of determining the timing and geometry of new ocean basin formation cannot be applied with confidence. The creation of a new ocean basin is accompanied by the formation of igneous rock, therefore an understanding of the types and ages of igneous rocks in the Canadian Arctic may help our understanding of the evolution of the Arctic Ocean. In this paper we document and interpret newly recognized igneous rock occurrences on Ellef Ringnes Is., Nunavut, and compare them to other igneous rocks in the Arctic. They include volcanic rocks that resulted from extrusion of magma at the earth¿s surface, and intrusive rock that resulted from solidification of magma below the surface. We document 6 periods of igneous activity between 130 and 101 million years ago. The ages include periods of igneous activity not recognized in other regions of the Arctic.