Shear-wave splitting in the lower crust beneath the Archean crust of southwest Greenland

Abstract

Slant stacks of seismic data from rifted ancient Archean crust along the southwest coast of Greenland indicate that the lower crust is strongly seismically anisotropic. The slant stack data show that a lower-crustal, 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 anisotropic above a high-velocity wedge in the lower crust. Possibly, magmatic underplating during Late Cretaceous Labrador Sea rifting heated the pre-existing lower crust promoting plastic flow and enabling alignment of anisotropic minerals to produce the seismic anisotropy.