Borehole seismic imaging of near‐vertical structures: A case history

Abstract

Conventional seismic methods are generally not effective for imaging geological structures with very steep dips, a common situation in some mining camps. Deep boreholes provide an alternative acquisition datum for seismic imaging in this type of setting. At the giant Kidd Creek CuZn deposit, the Archean volcanic stratigraphy has been folded and overturned so that most units are nearly vertical. Borehole logging and laboratory measurements conducted here show that certain stratigraphic contacts, especially those where massive-sulphide deposits and felsic host rocks are juxtaposed, are characterized by large impedance contrasts and are thus good candidates as seismic reflectors. To investigate this possiblity, a series of borehole-seismic profiling experiments were conducted in an area of known sulphide mineralization. Several source configurations were used, yielding both vertical and horizontal seismic images of the volcanic stratigraphy. In addition to observing reflections that correlate with stratigraphic contacts, prominent seismic anomalies were detected and have been correlated with a known massive-sulphide deposit.