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Anomalous upper mantle structure beneath the Cretaceous Fogo seamounts indicated by P-wave reflection delays

Nature volume 274, pages 788791 (24 August 1978) | Download Citation

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Abstract

TRAVEL-TIME residuals of teleseismic PP waves, reflected approximately halfway between the source and receiver, may give information on seismic velocity near the reflection point. Effects due to structure near the source and receiver are minimised by subtracting the residual of the direct P-wave from that of the PP arrival1. If these differential PP–P residuals are available for closely spaced reflection points, a contour map of compressional wave delays for the reflecting region can be obtained, which may then be related to crustal and upper mantle structure. The contours of two-way delay times for P-waves reflected beneath Atlantic Canada have been presented1, and show an area of late reflections south of the Grand Banks, centred at about 42° N, 52 °W. This area coincides with the Fogo seamounts (Fig. 1) and the relationship between these near-surface features and the P delays is examined here in more detail.

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Affiliations

  1. Department of Physics, Memorial University, St John's, Newfoundland, Canada

    • IAN C. F. STEWART
  2. Atlantic Geoscience Centre, Geological Survey of Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada

    • C. E. KEEN

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https://doi.org/10.1038/274788a0

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