Seismic anisotropy and mantle structure of the Rae craton, central Canada, from joint interpretation of SKS splitting and receiver functions

Earthquakes recorded at 36 stations in Nunavut between 1992 and 2011 and analyzed jointly using receiver-function and SKS-splitting techniques indicate the presence of multiple, dipping anisotropic layers in the lithosphere beneath the northern Hudson Bay and Baffin Island region. Prominent discontinuities indicate layers interpreted to dip at 6–30° at depths between 50 and 150 km beneath ten of the stations. One set of regionally continuous discontinuities in anisotropic fabric in the southeastern Rae craton dip gently southeast consistent with underthrusting beneath the Hearne and Meta Incognita-Sugluk blocks. SKS splitting recorded at twelve stations indicate patterns characteristic of two layers of anisotropic fabric. The deeper fabric as well as the single fast polarization direction recorded at other stations appears aligned with recent plate motion. The shallower fabric orientations at stations on and south of Southampton Island in northern Hudson Bay are consistent with known crustal fabric orientations formed during early (pre-1.85 Ga) stages of the Hudsonian orogeny. The shallower fabric north and west of Southampton Island has a more northerly orientation and is associated with west-dipping discontinuities that may correspond to Neoarchean accretion of the Mesoarchean north Rae domain to the central Rae domain.

► Seismic anisotropy occurs in either one or two layers beneath northern Hudson Bay, Canada.
► The deeper layer's fabric appears aligned with plate motion.
► The shallow one represents fossil structure from Proterozoic or Archean tectonics.
► Seismic discontinuities occur at 50–130 km depths.