SHEAR-WAVE SPLITTING IN THE LOWER CRUST BENEATH THE ARCHEAN CRUST OF SOUTHWEST GREENLAND

Slant stacks of seismic data from rifted ancient Archean crust along t he southwest coast of Greenland indicate that the lower crust is stron gly seismically anisotropic. The slant stack data show that a lower-cr ustal, wide-angle S-wave reflection has a different intercept time and ray parameter on the radial and transverse components from a receiver gather recorded on PASSCAL REFTEK three-component seismometers. From the S-wave analysis, the continental crust is clearly seismically anis otropic above a high-velocity wedge in the lower crust. Possibly, magm atic underplating during Late Cretaceous Labrador Sea rifting heated t he pre-existing lower crust promoting plastic flow and enabling alignm ent of anisotropic minerals to produce the seismic anisotropy.