Structural Modes of the western Margin of the Labrador Sea

Grant, A C

doi:10.4095/102519

Cited by 8 publications

(10 citation statements)

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“…1). Grant (1975) has described the seismo-stratigraphy obtained from the reflection profiles, correlating the stratigraphies from deep exploratory wells with seismic reflectors. Within graben-like basins on the north-eastern Grand Banks, Late Cretaceous and younger sediments are found above a mid-to Lower Cretaceous unconformity.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…Within graben-like basins on the north-eastern Grand Banks, Late Cretaceous and younger sediments are found above a mid-to Lower Cretaceous unconformity. Below the unconformity, Jurassic and older sediments are present, often exceeding 5 km in thickness (Grant 1975;Jansa & Wade 1975;Swift, Switzer & Turnbull 1975;Cutt & Laving 1977). On the basis of these studies, the 1.8 to 3 kms-' velocities are attributed t o Late Cretaceous and younger sediments with thickness of 2 to 2.5 km.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…This cross-section incorporates seismic measurements of Sheridan & Drake (1968) as well as those described here. Sediment thicknesses were obtained from Grant (1975). The gravity and magnetic anomalies along this profile are also shown (see also Haworth 1977 for simplified contour maps of the region).…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…A cross-section through the Orphan Basin region, based on the seismic refraction data reported here, and that of Sheridan & Drake (1968). Sediment thicknesses were also obtained from Grant (1975). The gravity (solid) and magnetic (dashed) anomalies are also shown.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…presented the results of gravity and magnetic surveys across these C. E. Keen and D. L. Barrett (Sheridan & Drake 1968;Dainty et al 1966) and the two lines reported here. The dashed lines are multichannel seismic reflection lines through Orphan Basin and Flemish Pass discussed by Grant (1975). Deep exploratory wells on the shelf for which the subsidence history has been described by Keen (1979) basins.…”

Section: Introductionmentioning

confidence: 99%

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Thinned and subsided continental crust on the rifted margin of Eastern Canada: crustal structure, thermal evolution and subsidence history

Keen

Barrett

1981

Geophysical Journal International

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Seismic refraction measurements were carried out using ocean bottom seismometers over foundered continental crust in Orphan Basin and Flemish Pass, on the continental margin north-east of Newfoundland. Tau-p travel time inversion, synthetic seismogram analysis and conventional layered model calculations were applied to the data. The results show that these outer regions of the margin are underlain by thinned continental crust, with a total depth to the M discontinuity of about 22km. There are two main crustal layers with P-velocities of about 6.1 and 7.0 km s-' which appear to be homogenous, and separated by sharp interfaces. These are overlain by a layer in which P-velocities are about 5.5 km s-'; this is interpreted to be Precambrian or Palaeozoic basement. Mesozoic and Cenozoic sediments cover the basement rocks, and are over 4 km thick.The results imply that crustal thinning to about 50 per cent of the original crustal thickness occurred. The gravity anomaly data show that the thin crust has a maximum horizontal extent of about 450 km, from the ocean-continent boundary near Orphan Knoll landward to the outer continental shelf. The subsidence history and thermal evolution of the region was computed, assuming that the observed thinning is produced by horizontal extension of the lithosphere. It is suggested that extension can only satisfy the observed crustal structure and elevation of the margin during the rift phase if more extension took place in the lower lithosphere than in the upper lithosphere. The computed subsidence is compared to the observed subsidence and the total amounts of subsidence are similar. However, the shape of the observed subsidence curves measured in deep exploratory wells differs significantly from the predicted subsidence, assuming cooling began when final continental breakup occurred in the Late Cretaceous. The temperature distribution within the lithosphere due to extension may be related to the flexural rigidity of the plate as a function of both time and position across the margin. Therefore, it is suggested that the response of the lithosphere to sediment loading, and the large amplitude of the gravity 'shelf-edge' anomalies are directly related to the thermal history of the region.

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Section: Discussion Of Resultsmentioning

confidence: 99%

Section: Discussion Of Resultsmentioning

confidence: 99%

Section: Discussion Of Resultsmentioning

confidence: 99%

Section: Discussion Of Resultsmentioning

confidence: 99%