A recent seismic refraction experiment in the deep central region of Baffin Bay showed that it is underlain by oceanic crust. This paper describes the results of gravity, magnetic, and seismic reflection profiling measurements in the bay. There is no definitive evidence for a buried ridge or for magnetic lineations in the center of the area. The magnetic and gravity anomaly fields have been used to define the boundary between the oceanic and continental crust around the bay and therefore the extent of oceanic crust presumed to have been formed by sea-floor spreading. Some of the characteristics of the seismic reflection lines across the continental margins, perhaps typical of this area, are also discussed. The results have been used to reconstruct the history of opening of Baffin Bay in conjuction with geophysical measurements in the Labrador Sea to the south and over the Alpha Ridge in the Arctic Ocean to the north. An attempt has been made to reconcile the geometry of opening with continental geology. Two phases of spreading are suggested. The first involves openings, in both the Labrador Sea and in Baffin Bay, about a pole in the Canadian Arctic Islands. The second, most recent stage of opening, requires that the Nares Strait was once a transform fault, perhaps connecting a Baffin Bay spreading center to the Alpha Ridge to the north.
Preliminary analyses of gravity, magnetic, seismic reflection and refraction, dredging, and heat flow measurements off Queen Charlotte Islands and Vancouver Island are presented. Seismic reflection and gravity measurements show the presence of a sedimentary basin at the foot of the continental slope in which the sediments are progressively more intensely deformed from north to south, indicating the interactions between the lithospheric plates. Heat flow values in the northern part of Explorer Ridge, and recovery of fresh basalts with little mineral coating in this region suggest that Explorer Ridge is a presently active spreading segment of East Pacific Rise. Seismic Refraction results in the deep ocean basin west of Queen Charlotte Islands show a marked anisotropic mantle P wave velocity, the direction of maximum velocity being 107° east of north and the maximum change in velocity being about 0.6 km/s.
Continuous seismic profiler surveys have defined the limits of the Paleozoic outlier in Ungava Bay, and indicate that similar rocks occur. to the north beneath Hudson Strait. These surveys have shown also that the strata underlying Hudson Strait are down-warped to form a synclinal structure with its axis parallel to the bathymetric trend of the Strait. Extrapolations based upon the dips and thicknesses indicated on the seismic profiler records and on physiographic evidence, suggest that the southwestern side of Hudson Strait has been down-faulted relative to the block of Paleozoic strata in Ungava Bay. These relationships postulated on the basis of seismic profiler results are supported by aeromagnetic, sea-magnetometer, and seagravimeter data from that region. A seismic and magnetic profile from Frobisher Bay indicates that a Paleozoic outlier occurs there as well. Although the submarine physiography of this region is primarily controlled by structure and secondarily modified by sub-aerial erosion, glacial erosion may account for local detail.
No abstract
The distribution of sediment on the crest mountains and high fractured plateau of the Mid-Atlantic Ridge at 45° N has been studied by seismic profiling. Sediment is ponded in intermontane valleys within the crest mountains and the plateau. It is also draped over the highlands of the plateau. Mean sediment thickness increases with distance from the valley out to 160 km, the limit of the study. The sediment data is not conclusive with regard to a break or change in the rate of the ocean-floor spreading between 8 and 10 m.y. ago in this area. Rates of sedimentation have been a few cm/1000 y during the past few m.y. It may have been more rapid in the past 100 000 y.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.