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Titre3D seismic imaging of VMS deposits: Halfmile Lake and Lalor Lake, Canada
AuteurBellefleur, G
SourcePDAC 2014, Geophysics session abstracts; 2014 p. 1
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140316
RéunionProspectors and Developers Association of Canada; Toronto; CA; mars 2-5, 2014
Medianumérique; en ligne
Lat/Long OENS-100.5000 -100.0000 56.0000 55.7500
Sujetsinterpretations sismiques; gîtes volcanogènes; gîtes sulfureux; ondes sismiques; minéralisation; géophysique; Précambrien
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
We present two case studies showing the response of two VMS deposits on 3D seismic data. The first 3D data set was acquired over the Halfmile Lake deposit located in New Brunswick and allowed the discovery of a 6 Mt VMS zone located at a depth of 1.2 km. The deep VMS zone is known for its strong P-wave amplitude response observed on 3D seismic data and its asymmetric diffraction signature. Multi-component borehole seismic measurements at Halfmile Lake confirmed the strong P-wave anomaly but also revealed additional ore signatures including P-S, S-P, and S-S wave-modes on horizontal receivers. The P-S, S-P, and S-S scattered waves, if properly recorded on surface 3D-3C (multi-component) data, represent useful signals that could help the targeting of deep sulphide mineralization. The P-S, S-P, and S-S signatures were further investigated with physical rock property analysis and elastic finite-difference modeling conducted over a geologically realistic 2D representation of the Halfmile Lake deposit. The model is constrained by geological information from surface mapping and boreholes, whereas petrophysical properties are provided by wireline logging data acquired in two boreholes intersecting different parts of the deposit. Finite-difference modeling results correlate well with borehole data and further suggest that modeconverted waves, in particular S-P waves, may have been recorded on the surface 3D seismic data, although this survey was acquired with point explosive sources (i.e., no Swave sources) and vertical geophones.