Refraction and wide-angle reflection seismic data collected in northern Saskatchewan and Manitoba in 1993 by LITHOPROBE provide new glimpses of the deep structure of the lithospheric mantle beneath the Trans-Hudson Orogen. Velocity models obtained through ray-tracing modelling techniques revealed the presence of complicated mantle structures down to a depth of 160 km beneath the orogen. Like the crust, the lithospheric mantle appears to show a seismically transparent upper and a highly reflective lower part, suggesting that the rheological environment responsible for development of reflections in the lithospheric mantle and of that in the crust are similar. This appears to be consistent with the observation that the strong and brittle upper 30 km of the mantle contain remnants of former tectonic processes in a form of velocity anisotropy, and the lower, more ductile zone seems highly reflective and isotropic. The suspected beginning of the lithosphere-asthenosphere transition zone at a depth of 160 km, imaged as gradual disappearance of mantle reflections, coincides well with models established using other geophysical methods.
ASJC Scopus subject areas
- Earth-Surface Processes