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TitleComparative geochemistry of volcanic rocks dredged from the Alpha Ridge and HALIP volcanic-intrusive complexes, northern Ellesmere Island, Canadian Arctic
AuthorWilliamson, M -CORCID logo; Weis, D; Saumur, BORCID logo; Kingsbury, C G; Kellett, DORCID logo; Davis, B; Oakey, G; Shimeld, J; MacDonald, D; Jackson, SORCID logo; Lawley, CORCID logo; Petts, DORCID logo; Abraham, A
SourceChapman Conference: Large-scale Volcanism in the Arctic: The Role of the Mantle and Tectonics, abstracts; 2019 p. 74-75 Open Access logo Open Access
LinksOnline - En ligne (complete volui\me - volume complet, PDF, 3.32 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20190138
PublisherAmerican Geophysical Union
MeetingChapman Conference: Large-scale Volcanism in the Arctic: The Role of the Mantle and Tectonics; Selfoss; IS; October 13-18, 2019
Mediaon-line; digital
File formatpdf
NTS39E; 39F; 39G; 39H; 49E; 49F; 49G; 49H; 59E; 59F; 59G; 59H; 120; 340; 560
AreaEllesmere Island; Heiberg Island; Canadian Arctic Islands
Lat/Long WENS -96.0000 -52.0000 84.0000 78.0000
Subjectsgeochemistry; igneous and metamorphic petrology; geochronology; geophysics; Science and Technology; Nature and Environment; tectonic history; magmatism; volcanism; intrusions; dykes; sills; bedrock geology; lithology; igneous rocks; volcanic rocks; lava flows; basalts; trachybasalts; rhyolites; tuffs; volcaniclastics; intrusive rocks; gabbros; radiometric dating; argon argon dating; isotopic studies; strontium strontium ratios; neodymium; geophysical interpretations; magnetic interpretations; High Arctic Large Igneous Province (HALIP); United Nations Convention On The Law Of The Sea (Unclos); Surprise Fiord Dyke Swarm; Lightfoot River Dyke Swarm; Buchanan Lake Sill Complex; South Fiord Complex; Middle Fiord Complex; Isachsen Formation; Strand Fiord Formation; Tanquary Fiord Sill; Ekblaw Lake Sill; Piper Pass Intrusive Complex; Wooton Igneous Complex; Hassel Formation; Hansen Point Rift Volcanics; Alpha Ridge; Piper Pass Intrusive Complex; Phanerozoic; Mesozoic; Cretaceous
ProgramDelineating Canada's Continental Shelf Under UNCLOS
Released2019 10 01
AbstractThe Canadian portion of the High Arctic Large Igneous Province (HALIP) ranges in age from ~125 to 80 Ma. On Axel Heiberg Island and northern Ellesmere Island, the HALIP was emplaced episodically at several volcanic-intrusive complexes (VIC). Each VIC is characterized by a distinct eruptive style, narrow range of crystallization ages and geochemical signature. On Axel Heiberg Island (Type 1 VIC; ~120-95 Ma), tholeiitic lava flows and associated gabbroic sills and dykes of subalkaline affinity predominate. Type 1 VICs include the Surprise Fiord and Lightfoot River dyke swarms; Buchanan Lake sill complex; South Fiord and Middle Fiord complexes; and lava flows in the Isachsen Formation and Strand Fiord Formation. On northern Ellesmere Island (Type 2 VIC; ~92-90 Ma) igneous rocks consist of olivine normative, mildly alkaline (transitional) ferrobasaltic lavas and gabbros (Tanquary Fiord and Ekblaw Lake sills; Piper Pass intrusive complex; Wooton Igneous Complex; and lava flows in the Hassel Formation). The Hansen Point Rift Volcanics (HPRV; Type 3 VIC; ~80 Ma) consist of alkali olivine basalt, trachybasalt and rhyolite erupted from volcanic centres and lava domes. The classification of HALIP rocks into VICs enables a comparison with volcanic rocks dredged from the Alpha Ridge (AR) under Canada's United Nations Convention on Law of the Sea (UNCLOS) Program. The samples consist of lapilli tuff with vitric and lithic fragments. The juvenile clasts consist of mildly alkaline (transitional) basalt glass with abundant plagioclase microlites. The plagioclase microlites yielded a 90 Ma 40Ar/39Ar age. Cognate basalt clasts are comagmatic volcanic rocks that were explosively broken and mixed with juvenile magma during eruption. A large basalt clast extracted from the AR lapilli tuff yielded 87Sr/86Sr of 0.703148 and epsilon-Nd of +7.24. The AR sample plots in the mantle array and shows a close geochemical affinity with ferrogabbros of the Piper Pass intrusive complex and some Mg-rich basaltic lavas in the HPRV. This isotopic similarity suggests that the AR lapilli tuff is contemporaneous with VICs exposed on northern Ellesmere Island. The Alpha Ridge and Type 2 VIC characteristically display high magnetic anomalies that could result from the emplacement of predominantly ferrobasaltic magmas in the interval 95-90 Ma.
Summary(Plain Language Summary, not published)
In August 2016, approximately 100 kg of volcanic rocks were successfully recovered from the Alpha Ridge, Arctic Ocean, by Canada's Extended Continental Shelf Program (UNCLOS Program). The samples consist of pyroclastic rocks (lapilli tuff) emplaced during an explosive eruption. The age of these rocks matches that of volcanic and intrusive rocks that are exposed on northern Ellesmere Island and belong to the High Arctic Large Igneous Province (HALIP). By comparing geochronological, geochemical and mineralogical data, we conclude that both onshore and offshore igneous rocks originated from the same mantle source.

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