GEOSCAN, résultats de la recherche


TitreGeology and volcanism along the Canadian Arctic Margin: New constraints from aeromagnetic mapping
AuteurOakey, G N; Damaske, D; Nelson, B
SourceInternational Polar Year 2012, abstracts volume; .
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110355
RéunionInternational Polar Year 2012; Montreal; CA; avril 22-27, 2012
ProgrammePreparation of a submission for an extended continental shelf in the Atlantic and Arctic Oceans under UNCLOS, Délimitation du plateau continental du Canada en vertu de la Convention des Nations Unies sur le droit de la mer (UNCLOS)
Résumé(disponible en anglais seulement)
In 2008, an airborne magnetic survey was carried out over the northernmost part of Ellesmere Island and the offshore as part of the German CASE11-Pearya Expedition in collaboration with the Geological Survey of Canada. The new survey ties with existing Polar Margin Aeromagnetic Program (PMAP) surveys flown in the 1990s and the 2010 IPY Arctic magnetic compilation. These data sets have been integrated to better understand the geology of the "Pearya" Exotic Terrane on Ellesmere Island, the overprinting of Cretaceous volcanic systems, and the geological affinity with the Alpha Ridge.
Within the new survey area, the onshore area is dominated by a broad magnetic low that correlates with Mesoproterozoic to Neoproterozoic crystalline basement of Pearya Succession 1 and Neoproterozoic to Ordovician metasediments of Pearya Succession 2. In the central and eastern portion of the survey area, this magnetic low continues offshore, suggesting that the Pearya Terrane continues to the edge of the margin. Isolated high amplitude positive magnetic anomalies generally correlate with Paleozoic ultramafic intrusives (eg. Cape Fanshaw Martin Pluton). A magnetic high extending from the mouth of M'Clintock Inlet, across Bromley Island and Cape Richards, to Ayles Fiord, correlates with Ordovician volcanics of Pearya Successions 3 and 4 (Cape Richards Intrusive Complex), and extends offshore north of Disraeli Fiord.
At the western edge of the new survey area, a ridge of high amplitude N-S oriented positive anomalies extending from the mouth of Yelverton Inlet to north of Milne Fiord appears to be a continuation of the NE-SW oriented linear magnetic anomaly over the Cretaceous volcanics on Wooton Peninsula. Further west, isolated linear positive magnetic anomalies correlate with exposures of the Cretaceous Hansen Point Volcanics, and at Emma Fiord a major extrusive volcanic epicenter with radiating dikes and sills is imaged in the magnetic data.
North of Ayles Fiord, the magnetic high separates into individual E-W oriented linear positive magnetic anomalies which cross-cut the longer wavelength anomalies produced by the Pearya basement rock, and continue to the eastern end of the new survey area, suggesting that Cretaceous volcanic intrusives are present all along the near-shore portion of the margin. There is a pronounced termination of these shallow-sourced features against a SSW-NNE oriented boundary extending north from Clements Markham Inlet to the southeast edge of the Lomonosov Ridge, which we interpret as the eastern extent of the Pearya Terrane. On the southern region of the Lomonosov Ridge, a pronounced high-amplitude circular magnetic anomaly is observed with a surrounding radiating pattern of linear positive magnetic anomalies. This feature closely resembles the Cretaceous extrusive volcanic epicenter at Emma Fiord.
North of the new survey area, the broad long-wavelength offshore magnetic highs are attributed to Cretaceous volcanics deeply buried beneath Tertiary sedimentary deposits. A linear magnetic high extends from M'Clintock Inlet to the northwest, linking with the high amplitude magnetic anomalies over the Alpha Ridge suggesting that the Cretaceous volcanic system along the Canadian Arctic Margin is directly related to the High Arctic Large Igneous Province that formed the Alpha Ridge.