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TitleTectono-magmatic elements of the Alpha Ridge and possible associations with the High Arctic Large Igneous Province
AuthorShimeld, J; Funck, T; Li, Q; Oakey, G N; Boggild, K; Jackson, RORCID logo
SourceOnline Program for the 2019 Chapman Conference on Large-scale Volcanism in the Arctic: The Role of the Mantle and Tectonics; 2019 p. 1 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20190135
PublisherAmerican Geophysical Union
Meeting2019 Chapman Conference on Large-scale Volcanism in the Arctic: The Role of the Mantle and Tectonics; Selfoss; IS; October 13-18. 2019
DocumentWeb site
Mediaon-line; digital
File formathtml; pdf
ProvinceNunavut; Northern offshore region
AreaArctic Ocean
Subjectstectonics; regional geology; geophysics; Science and Technology; Nature and Environment; tectonic history; tectonic elements; magmatism; intrusions; emplacement; faulting; geophysical interpretations; seismic interpretations; seismic profiles; bedrock geology; lithology; bathymetry; diapirs; Alpha Ridge; High Arctic Large Igneous Province (HALIP); Fedotov Seamount; Nautilus Spur; Marvin Spur; Phanerozoic; Cenozoic; Mesozoic; Cretaceous
ProgramDelineating Canada's Continental Shelf Under UNCLOS
Released2019 10 01
AbstractPublished seismic interpretations suggest that the Alpha Ridge consists of voluminous tuff deposits and possible intercalated sediments, overlain by an upper carapace of basalt flows and sills emplaced no later than the Campanian, possibly during the youngest magmatic phase of the High Arctic Large Igneous Province (HALIP). The Alpha Ridge is widely posited to be an offshore component of HALIP, yet the constructional history of the ridge remains largely unknown.
Coincident seismic reflection and refraction data collected during the 2016 Canada-Sweden Polar Expedition across the northern and southern flanks of the Alpha Ridge reveal a range of igneous phenomena, and allow preliminary identification of important tectono-magmatic elements. Depth conversion of the seismic reflection profiles enhances details of the igneous crust and its internal reflection geometries. Positive bathymetric features on the ridge, such as the Fedotov Seamount, exhibit acoustic facies interpreted as stacked effusive volcanic sequences emanating from discrete volcanic centres. Along the southern ridge periphery, at the Nautilus Spur, wedge-shaped sequences with dipping internal reflections manifest outbuilding of the ridge during early constructional phases. There is no clear evidence for significant amounts of either syn- or post-magmatic tectonic faulting, but igneous intrusions on the northern periphery of the ridge are broadly parallel to both the Marvin Spur and the CESAR valley, suggesting that a tectonic fabric in this orientation affected the conduits for magma delivery. A second fabric, at a high angle to the first, is especially evident along the southern ridge periphery where volcanic edifices are elongated in a broadly NE trend. Principal constructional phases of the ridge appear to have ended in the Late Cretaceous, but regionally significant magmatism persisted well into the Cenozoic, as demonstrated by igneous intrusion and disturbance of sediments overlying the ridge. Surprisingly recent activity may be indicated by a possible igneous diapir and disturbed sedimentary unit on top of the Fedotov Seamount, although these interpretations require confirmation through geological sampling.
Summary(Plain Language Summary, not published)
The Alpha Ridge is amongst the most prominent of the bathymetric features in the Arctic Ocean basin, yet there is little understanding about how it formed. Generally, it is thought to be part of a large igneous province that emplaced a wide variety of volcanic features across more than a million square km of the high Arctic during the Cretaceous Period (the High Arctic Large Igneous Province or HALIP). During the 2016 Canada-Sweden Polar Expedition, seismic reflection and refraction data were collected that provide valuable information about the velocity and nature of the igneous rocks comprising the Alpha Ridge. The results demonstrate a wide variety of igneous phenomena, some of which are consistent with known HALIP processes and some of which are not recognized as being HALIP-related.

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