scholarly journals A compilation of seismic reflection profiles across the continental margin of western Canada

1981 ◽  
Author(s):  
E E Davis ◽  
D A Seemann
Keyword(s):  
Continental Margin ◽  
Seismic Reflection ◽  
Western Canada ◽  
Seismic Reflection Profiles

Cretaceous strata on the Scotian Shelf

1970 ◽  
Vol 7 (1) ◽  
pp. 145-155 ◽  
Author(s):  
Lewis H. King ◽  
B. MacLean ◽  
Grant A. Bartlett ◽  
J. A. Jeletzky ◽  
William S. Hopkins Jr.
Keyword(s):  
Continental Margin ◽  
Seismic Reflection ◽  
Sedimentary Rock ◽  
Upper Cretaceous ◽  
Dredged Material ◽  
Scotian Shelf ◽  
Unconsolidated Material ◽  
Seismic Reflection Profiles ◽  
Early Upper ◽  
Cretaceous Sediment

Samples of Cretaceous sediment have been dredged from the Scotian Shelf at a locality 100 km north-northwest of Sable Island.Continuous seismic-reflection profiles across the sample area show the presence of well defined stratification within the bedrock. These beds are truncated by the slopes of submarine valleys which transect the area. Bedrock appears to outcrop along the upper portion of the valley walls or be covered by a layer of unconsolidated material so thin as to be beyond the resolution of the seismic equipment. The dredged material appears to have come from rubble heaps near the base of the valley slopes and is believed to have originated locally.Approximately 450 kg of sedimentary rock were recovered consisting principally of sideritic quartz sandstone and arenaceous sideritic carbonate, both with fossiliferous material. Glauconite is a significant constituent of many samples.The macrofauna include sufficiently diagnostic forms to suggest correlation with the early Upper Cretaceous (Cenomanian) though the possible presence of older or younger forms cannot be wholly excluded. The microflora and microfauna appear to correlate mainly with the Albian-Aptian, and Albian-Cenomanian, respectively.Cretaceous strata immediately underlie much of the central and eastern portions of the Scotian Shelf. Tertiary sediments reported by Marlowe and Bartlett overlie the Cretaceous toward the continental margin and appear to occur as a discontinuous veneer at other localities on the shelf.

Evolution of Precambrian continental lithosphere in Western Canada: results from Lithoprobe studies in Alberta and beyond

2002 ◽  
Vol 39 (3) ◽  
pp. 413-437 ◽  
Author(s):  
Gerald M Ross
Keyword(s):  
Seismic Reflection ◽  
Oceanic Lithosphere ◽  
Western Canada ◽  
Mafic Magmatism ◽  
Marginal Basin ◽  
Igneous Provinces ◽  
Basement Structures ◽  
Surface Manifestation ◽  
Seismic Reflection Profiles ◽  
Crustal Xenoliths

The Precambrian lithosphere of western Canada was assembled into the present crustal configuration between ca. 2.0–1.78 Ga by plate collisions, sometimes accompanied by arc magmatism, with subsequent cooling of the lithosphere since ca. 1.7 Ga. Collisional processes inferred along preserved plate sutures include (1) subduction of oceanic lithosphere and accretion of Proterozoic arc crust to the western Rae Province; (2) marginal basin consumption and tectonic entrapment of the Hearne Province between coeval subduction–collision zones; and (3) amagmatic marginal basin closure, perhaps analogous to the roots of small collisional orogens, such as the Pyrenees. Seismic reflection profiles acquired during the Lithoprobe Alberta Basement Transect have captured images of syn- to post-collisional structures along these sutures and evidence for crustal-scale thrust imbrication and rigid body accretion of Archean crust with preservation of precollisional tectonic fabric. The degree to which lithospheric mantle beneath Archean crustal blocks was preserved during these collisions is unknown, although tectonic geometries imply significant thermal and (or) mechanical interaction. Post-collisional, intrusive mafic magmatism is imaged widely in both seismic reflection and refraction surveys. These magmatic events are demonstrably Proterozoic, based on crosscutting relationships seen on seismic reflection profiles and geochronology of lower crustal xenoliths, and are comparable in scale to Phanerozoic igneous provinces (e.g., large igneous provinces) but have little preserved surface manifestation. Reactivation of Precambrian basement structures is limited or very subtle, reflecting strength control by the mantle on stress transmission and crustal failure. Long-wavelength elastic deformation of the crust during the Phanerozoic occurred in regions associated with, or adjacent to, Proterozoic mafic magmatism, suggesting local rheologic control of anomalous Phanerozoic paleotopography.

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