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TitleComparative geochemical and geophysical studies of volcanic rocks from the High Arctic Large Igneous Province (HALIP) and Alpha Ridge, Arctic Ocean
AuthorWilliamson, M C; Oakey, G N
Source 2017 p. 1227, 1 pages
LinksOnline - En ligne (p.1227)
Alt SeriesEarth Sciences Sector, Contribution Series 20160451
PublisherIAVCEI (International Association of Volcanology and Chemistry of the Earth's Interior) (Portland, US)
MeetingIAVCEI 2017 Scientific Assembly; Portland; US; August 14-18, 2017
Mediapaper; on-line; digital
File formatpdf
NTS59G; 59H; 560A; 560D; 49; 39; 340; 120
AreaAxel Heiberg; Ellesmere Island
Lat/Long WENS -97.0000 -72.0000 84.0000 76.0000
Subjectsfossil fuels; regional geology; metallic minerals; mineralogy; basalts; sills; dykes; lava flows; intrusions; igneous rocks; magnetic anomalies; picrites; rhyolites; rock geochemistry; mineral assemblages; mineral occurrences; mineral potential; Sverdrup Basin; Amerasia Basin; Hansen Point Rift Volcanics (HPRV); Cretaceous
ProgramPreparation of a submission for an extended continental shelf in the Atlantic and Arctic Oceans under UNCLOS, Delineating Canada's Continental Shelf Under UNCLOS
AbstractThe Canadian portion of the High Arctic Large Igneous Province (HALIP), exposed on Axel Heiberg Island and northern Ellesmere Island, consists of continental flood basalts, sills and dykes (~125-90 Ma); ferrobasaltic lava flows and associated intrusions (~92 Ma); and bimodal alkaline igneous rocks (~88-80 Ma). The HALIP magmatic event was triggered by tectonic rejuvenation of the Sverdrup Basin and the opening of the Arctic Ocean in the Early Cretaceous. Offshore, the Alpha-Mendeleev Ridge Complex (AMRC) is a first-order physiographic and geological feature of the Amerasia Basin that is characterized by high amplitude "chaotic" magnetic anomalies associated with large-scale regional magmatism. The approximate areal extent of the AMRC is ~1.3x106 km2, suggesting a total volume of igneous rocks of ~20x106 km3. The only dated volcanic rock sample recovered from the Alpha Ridge is ~89 Ma.

The Hansen Point Rift Volcanics (HPRV) consist of bimodal alkaline igneous rocks that were emplaced during the waning stages of the HALIP event. Previous studies have shown that lava flows consist of picritic basalt, alkali basalt, trachyandesite, trachyte and peralkaline rhyolite erupted from central vents. Whole rock geochemical analyses acquired for this study suggest that high-MgO lava flows (8.5-13.3 wt.%) have FeO* values of 8.9-10.7 wt.%; TiO2 values of 1.2-2.4 wt.%; are LREE-enriched (LaN/SmN: 3-5); and have low contents of HREE (e.g. Lu: 0.26-0.37). The most magnesian lava flow analysed so far is a ferropicrite with olivine (Fo84-87) and Ti-rich diopside phenocrysts set in a glassy matrix. This result is of interest to us because ferropicrites of Phanerozoic age occur as low volume lava flows or thin dykes associated with continental flood basalt provinces. They typically show high values of MgO, FeO*, Ni and Cr; moderate values of SiO2, and low values of Al2O3 and HREE, and are interpreted as Fe-rich melts generated from a mantle plume.

In August 2016, approximately 100 kg of volcanic rocks were successfully dredged from the Alpha Ridge during a collaborative Canada-Sweden Polar Expedition under Canada¿s UNCLOS (United Nations Convention on Law of the Sea) Program. We present new mineralogical, geochemical and magnetic susceptibility data for the onshore HPRV and volcanic rocks dredged from the Alpha Ridge. The results highlight the petrological significance of ferropicrites with implications for the magmatic evolution of the onshore HALIP and offshore AMRC.
Summary(Plain Language Summary, not published)
In August 2016, approximately 100 kg of volcanic rocks were successfully recovered from the Alpha Ridge, Arctic Ocean, during a Canada-Sweden polar expedition under the Extended Continental Program of Canada. We present new mineralogical, geochemical and magnetic susceptibility data for the Alpha Ridge samples of volcanic rock. The results are compared with data acquired for volcanic rocks of similar age from the Hansen Point Rift Volcanics on northern Ellesmere Island, Nunavut. This comparative geochemical study allows us to better understand the nature and origin of the Alpha Ridge, and potential links with the High Arctic Large Igneous Province (HALIP).