3D Diffraction and Mode-converted Scattering Signatures of Base-metal Deposits – Bathurst Mining Camp, Canada

The localized and isolated nature of base-metal deposits and their significantly contrasting elastic properties can generate complex scattering wavefield that may include P-P, P-S, S-P and S-S wave-modes. Multicomponent VSP data confirms presence of multi wave-modes scattered at a deep-seated base-metal deposit in Halfmile Lake, Bathurst Mining Camp, Canada. However, multi wave-modes scattering from a massive sulphide deposit has not yet been recognized on surface seismic data. In this study, we investigate the possible presence of P-P, P-S, S-P, and S-S wave-modes scattered at a base-metal lens at depth of about 1.2 km on 3D surface seismic data acquired with point explosive sources and vertical geophones. We show that the deep lens produces a diagnostic P-P diffraction and could produce mode-converted scattering signals. Results from a target-oriented azimuthal scattering analysis based on 3D prestack migration reveals amplitude anomalies at the location of the base-metal lens for S-P waves and possibly P-S waves. The identification of S-P and P-S wave modes confirms that mode-converted scattering occurring at the deep sulfide lens was recorded on the 3D data. However, the real potential of these complementary wave modes for mineral exploration will only be realistically achieved using shear-wave and multi-component surveys.