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Seismic evidence for a weakened thick crust at the Beaufort Sea continental margin
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  • Clément Estève,
  • Yajing Liu,
  • Ivan Koulakov,
  • Andrew J Schaeffer,
  • Pascal Audet
Clément Estève
McGill University

Corresponding Author:[email protected]

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Yajing Liu
McGill University
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Ivan Koulakov
Trofimuk Institute of Petroleum Geology and Geophysics, SB RAS, Novosibirsk, Russia
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Andrew J Schaeffer
Natural Resources Canada
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Pascal Audet
University of Ottawa
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The Canadian Beaufort Sea continental margin of northwestern Canada is a Cenozoic convergent margin, potentially representing a rare case of incipient subduction. Here, we produce P- and S-wave seismic velocity models of the crust and the uppermost mantle using recordings from regional earthquakes. Our models reveal a northwest-dipping very low-velocity anomaly within the crust (δV up to -15%) beneath the Romanzof Uplift. We interpret this low-velocity feature to correspond to a weaker and thicker crust due to shortening and stacking of igneous and sedimentary rocks. The co-location of the thickened crust and lack of present-day seismicity indicates that north-south compression is accommodated by slow, aseismic deformation in the narrow margin beneath the Romanzof Uplift or more broadly offshore. Neither interpretation requires a subduction initiation process.