Abstract

First-break travel time picks along about 250 km of the Lithoprobe SNORCLE deep reflection profile were inverted using a 2-D crossing-ray tomographic method to estimate bulk P-wave speed within the uppermost 2 km of crust beneath the Bowser Basin in northwest British Columbia. The purpose was to assess the usefulness of resulting wave-speed models in defining local stratigraphy and structure and in petroleum exploration more generally. Two areas were investigated in detail. Near the Oweegee Dome, deeper levels of exposure at the surface and stratigraphic correlations with a nearby drill hole suggest that a marked regional increase in wave speed occurs at the contact between the lowermost Bowser Lake Group strata and lava flows of the underlying Hazelton Group. Near the northwest corner of the Bowser Basin, a triangle zone inferred from surface structure does not show clearly in the seismic wave-speed model but does contain distinctive horizontal layers of higher wave speed that represent thrust duplexes, igneous intrusions, or mineralization.