Contrasting Styles of Lithospheric Extension Determined from Crustal Studies Across Rift Basins, Eastern Canada

  1. Raymond A. Price
  1. C. E. Keen

Published Online: 18 MAR 2013

DOI: 10.1029/GM048p0037

Origin and Evolution of Sedimentary Basins and Their Energy and Mineral Resources

Origin and Evolution of Sedimentary Basins and Their Energy and Mineral Resources

How to Cite

Keen, C. E. (1989) Contrasting Styles of Lithospheric Extension Determined from Crustal Studies Across Rift Basins, Eastern Canada, in Origin and Evolution of Sedimentary Basins and Their Energy and Mineral Resources (ed R. A. Price), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM048p0037

Author Information

  1. Atlantic Geoscience Centre, Geological Survey of Canada, Bedford Institue of Oceanography, Dartmouth, Nova Scotia, Canada, B2Y 4A2

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780875904528

Online ISBN: 9781118666654

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Keywords:

  • Sedimentary basins—Congresses;
  • Mines and mineral resources—Congresses;
  • Power resources—Congresses

Summary

Well constrained crustal cross-sections of the sedimentary basins on the rifted continental margin of the Grand Banks off eastern Canada have been derived by combining deep seismic reflection profiles, seismic refraction data, and borehole information. The cross-sections illustrate the crustal geometry resulting from extension during Mesozoic rifting and continental breakup. Furthermore, the syn- and post-rift subsidence history along the cross-sections was estimated, from which the amounts of crustal and mantle lithosphere stretching and thinning were inferred. The results show two contrasting regions which differ in the amount of lower lithospheric thinning. The Orphan Basin in the north is characterized by closely spaced, numerous faults in basement, which terminate at a mid-crustal decollement. Models ofthe subsidence history suggest that the sub-crustal lithosphere was thinned more than the crust during rifting. In contrast, half graben basins on the Grand Banks to the south are bounded by fewer, larger fault blocks, and the faults extend down to the lower crust or to the Moho, where they terminate in a decollement. The lower lithosphere does not appear to have thinned as much as the crust below these basins, although the thinning may extend well beyond the basin edges. These differences in the extensional geometry are related to thermal and mechanical properties of the extended lithosphere.