Seismic reflection and borehole geophysical investigations in the Matagami mining camp

Abstract

A high-frequency vibroseis seismic survey was conducted by Lithoprobe across a well-known section of the Matagami mining camp to assess the usefulness of seismic methods in lithological mapping. The data have been reprocessed to enhance shallow reflections. Critical processing steps for the preservation of the shallow features include refraction static corrections, cross-dip corrections, and first break mutes. The seismic data were calibrated using geophysical logs from two boreholes adjacent to the profile. Physical rock property measurements suggest that strong reflectivity within the volcanic sequence occurs at rhyolite-gabbro contacts. The Lower Wabassee Group, a sequence of gabbros and basalts with interlayered rhyolite horizons, has been identified as a seismic marker. This reflective package overlays the horizon where most sulphide deposits are known to be located. In the Matagami mining camp, seismic reflection methods can be used to map the deep volcanic stratigraphy and structures.