Crustal Thickness, Seismicity, and Stress Orientations of the Continental Margin of Eastern Canada

Shih, K G; Kay, W; Woodside, J; Jackson, Ruth; Adams, John; Drysdale, J A; Bell, J S; Podrouzek, A J

doi:10.4095/125188

Cited by 3 publications

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“…Crustal thicknesses in the Slave Province on the western mainland are taken from Bank et al (2000). The hatched region indicates oceanic crust in Baffin Bay and the Labrador Sea (after Shih et al 1988), and the hatched line to the north shows the position of the Arctic continental margin. The Canadian Shield is shaded in pale grey and the Sverdrup Basin is shaded in dark grey.…”

Section: Discussionmentioning

confidence: 99%

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Darbyshire¹

2003

Geophysical Journal International

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SUMMARY Results from an investigation of the crustal structure beneath the Canadian High Arctic and western Greenland are presented, using teleseismic data recorded by a network of 12 three‐component broad‐band seismograph stations deployed across the region. Of these stations, eight were deployed in summer 2000, in order to improve the spatial density of seismographs in this tectonically active but little studied region, in order to provide more information on the patterns of seismicity and the structure of the area. The typical station separation is of the order of 400–600 km, a substantial improvement on the previous >1000 km spacing afforded by the permanent broad‐band network. Teleseismic receiver functions are used to model the shear wave velocity structure of the crust beneath the stations, using both 1‐D and 3‐D analysis techniques. The velocity–depth models show significant variation in the thickness and nature of the crust across the region. In the south and east, where the seismic stations lie on the Canadian Shield, the crustal structure is relatively simple, with Moho depths ranging from 35 km on the Boothia Peninsula to 45 km beneath southern Baffin Island. Further to the north and west, where the lithosphere has been deformed by orogenic events and basin formation, the patterns of azimuthal variation in the radial and tangential receiver functions suggest 3‐D structure throughout the crust. The Moho depths around the margins of the Sverdrup Basin lie in the range 33–37 km. At Mould Bay, on the western margin of the basin, a 5 km thick low‐velocity layer overlies the main crustal sequence. The base of this layer can be modelled as a planar dipping structure with a southeasterly strike. The thinnest crust (27–32 km) is modelled at Alert, on the northern coast of Ellesmere Island. In the southwest of the Arctic archipelago, tangential receiver functions at Holman show a pattern consistent with crustal anisotropy. The Moho depth in the region is undetermined; a layer of intermediate shear wave velocity, consistent with mafic lower‐crustal material, is modelled at depths of 35–55 km. The region around Holman lies at the focal point of the Mackenzie dyke swarm, believed to result from plume activity; therefore the intermediate‐velocity layer may result from mafic underplating caused by the presence of the Mackenzie plume.

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Section: Discussionmentioning

confidence: 99%

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Darbyshire¹

2003

Geophysical Journal International

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“…Borehole deformation (Fig. 1) shows that the region is being compressed from the northeast (Shih et al 1988) because of subcrustal drag as a result of plate drift (Plumb and Cox 1987). Modem seismicity is linked to postglacial stress release along reactivated basement faults (Stein et al 1979), including pluton margins (Burke 1984), as exemplified by coseismic thrusting from the 1982 New Brunswick earthquake (Basham and Adams 1984).…”

Section: Regional Tectonic Compressionmentioning

confidence: 96%

Late Quaternary movement of Aspy Fault, Nova Scotia

Grant¹

1990

Can. J. Earth Sci.

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An emerged Sangamonian (125 ka) intertidal rock platform at +7 r n as1 is apparently upthrown to +22 m as1 along Aspy Fault on Cape Breton Island. The 15 m displacement may be an isostatic response to rapid ice retreat or erosional unloading, or it may be a tectonic effect due to release of crustal stress stored during Wisconsinan glacier cover.Une plate-forme rocheuse intertidale CmergCe, formCe au Sangamonien (125 ka), ClevCe de 7 m au-dessus du niveau de lamer fut apparernment soulevCe a +22 m au-dessus du niveau de la mer le long de la faille Aspy sur 1'Ile du Cap Breton. Le dkplacement de 15 m peut Ctre une rCponse isostatique au retrait rapide des glaciers ou une diminution de charge par Crosion, ou un effet tectonique crCt par la dCtente des contraintes cmstales emmagasinkes durant la pCriode de la couverture glaciaire wisconsinienne.

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A review of three transform margins off eastern Canada

Reid

Jackson

1997

Geo-Marine Letters

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Crustal Thickness, Seismicity, and Stress Orientations of the Continental Margin of Eastern Canada

Cited by 3 publications

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Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Crustal structure across the Canadian High Arctic region from teleseismic receiver function analysis

Late Quaternary movement of Aspy Fault, Nova Scotia

A review of three transform margins off eastern Canada

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